JPH0517431B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to the control of an automatic transmission mounted on a vehicle, in which a back-up pressure is supplied to a friction element that is engaged during engine braking in order to prevent the friction element from slipping. This invention relates to a backup pressure control device for an automatic transmission. Prior Art This type of back-up pressure control device includes, for example, the 1984 maintenance manual "Automatic Transaxle" published by Nissan Motor Co., Ltd.
RN4F02A type, RL4F02A type (published in February 1981)
There is something like the one shown. That is, the backup pressure control device used in this automatic transmission is equipped with a backup valve, and selects the manual range (range or range) from 4th or 3rd gear in the automatic transmission range (D range) to 2nd gear. When the gear is downshifted, the backup valve is operated to supply the highest line pressure to the pressure modifier valve. Then, the signal pressure supplied from the pressure modifier valve to the pressure regulator valve is set high, and the line pressure regulated by the regulator valve is set even higher. The pressure is supplied as backup pressure to a friction element (clutch, band brake, etc.) that is engaged in the manual range. That is, when the gear is shifted down from the high gear of the D range to the manual range, engine braking is applied, and during this engine braking, torque from the wheel direction is applied to the friction element, but a high engagement pressure (backup pressure) is applied to the friction element. By supplying this, the friction elements are prevented from slipping, the engine braking function is fully exerted, and the friction elements are prevented from being burnt out. Figure 9 shows the hydraulic pressure (control pressure for automatic transmission) characteristics in a conventional backup pressure control device. In the idling state when engine braking is applied, the backup pressure shown by the broken line is significantly higher than the other line pressure characteristics shown by the solid line. It is set high. Problems to be Solved by the Invention However, in such conventional backup pressure control devices, no consideration is given to the gear position at the start of engine braking, that is, the gear position immediately before switching to the manual range. In other words, for example, if you compare a case where the car was running in 4th gear just before and a case where it was running in 3rd gear, if the vehicle speed is the same, due to the difference in the gear ratio, the car was running in 4th gear just before. The engine speed is relatively low when the engine is in the 2nd gear position, and a large negative torque is generated in the engine when the manual range is set to 2nd gear.
The torque received by the friction element is greater than when the vehicle was previously traveling in third gear and then shifted to second gear. Therefore, the engagement pressure of the friction element during engine braking is required to have a larger value in the former case. However, conventionally, the backup pressure is always given at a constant value regardless of the conditions at the time of switching. Therefore, in order to reliably prevent slippage of the friction elements, it is necessary to set the backup pressure to meet the highest required value, for example, the requirement at the fourth gear. Therefore, if the engine brake is applied by switching to manual range while driving in third gear, the backup pressure, that is, the engagement pressure of the friction elements becomes relatively excessive, and the engagement shock of the friction elements becomes significantly large. There was a problem that the ride quality worsened. Therefore, the present invention has been developed to optimally control the backup pressure according to the operating state at the start of the engine braking action, that is, the gear position immediately before switching to the manual range, so that it is possible to prevent the friction element from slipping and to prevent the engagement shock. The object of the present invention is to provide a backup pressure control device for an automatic transmission. Means for Solving the Problems As shown in FIG. 1, the automatic transmission backup pressure control device of the present invention includes an overrun clutch a for applying engine braking in parallel with a one-way clutch, When switching from the range to the manual range, back-up pressure generated by increasing the line pressure is supplied to the overrun clutch a to switch the overrun clutch a.
An automatic transmission configured to engage an actuator having an actuator actuated by a control signal,
A line pressure control means b that variably controls the line pressure that becomes the backup pressure based on the control signal, a range change detection means c that detects a switching operation from an automatic shift range to a manual range, and a range change detection means c that detects a switching operation from an automatic shift range to a manual range, and A gear position detection means d detects the gear position in the automatic transmission range, a backup pressure setting means e sets a target backup pressure such that the higher the gear position is, the higher the pressure is, and the backup pressure setting means e The above line pressure control means b
The present invention is characterized in that it includes a drive control means f that outputs a control signal to. Operation When the automatic shift range is switched to the manual range, a predetermined shift control is performed, and at the same time, line pressure is supplied to the overrun clutch a as backup pressure, and the overrun clutch a is engaged. This provides engine braking. At this time, when the range change detection means c detects a change to the manual range, the gear position detection means d detects the gear position immediately before the change, and the backup pressure setting means e sets the target backup pressure in consideration of the gear position. is set. This target backup pressure is given so that the higher the previous gear position is, the higher the pressure is. Then, the actuator of the line pressure control means b is controlled by the drive control means f in accordance with this target backup pressure, and the line pressure is increased so as to reach the target backup pressure. Examples Examples of the present invention will be described in detail below with reference to the drawings. That is, FIG. 2 shows an overall circuit showing an embodiment of a hydraulic pressure control device using the backup pressure control device of the present invention, and is used as a power transmission train of an automatic transmission controlled by this hydraulic pressure control device. For example, the third
There are some as shown in the schematic diagram of the figure. That is, this power transmission train includes a torque converter 3 that transmits rotation from the engine output shaft 1 to the input shaft 2, a first planetary gear set 4, a second planetary gear set 5, an output shaft 6, and various friction elements described below. Consisting of: The torque converter 3 is driven by the engine output shaft 1 and includes a pump impeller 3P that is also used to drive the oil pump O/P, and a turbine that is fluidly driven by the pump impeller via internal working fluid and transmits power to the input shaft 2. placed on a fixed shaft via a runner 3T and a one-way clutch 7,
It consists of a stator 3s that increases the torque to the turbine runner 3T, and a lock-up clutch 3 is attached to this stator 3s.
This is a normal lock-up torque converter with L added. The torque converter 3 is supplied with working fluid from the release chamber 3R, and while the working fluid is removed from the apply chamber 3A, the lock-up clutch 3L is released and the engine power is pumped through the impeller 3P and the turban runner 3T ( (in the converter state) torque is transmitted to the input shaft 2 while increasing, and while the working fluid is supplied from the apply chamber 3A and the working fluid is removed from the release chamber 3R, the lock-up clutch 3L is engaged and the engine power is increased. is transmitted as is to the input shaft 2 via this lock-up clutch (in the lock-up state). In the latter lock-up state, the slip of the lock-up torque converter 3 (relative rotation of the pump impeller 3P and the turbine runner 3T) is arbitrarily controlled (slip control) by reducing the working fluid displacement pressure from the release chamber 3R. be able to. The first planetary gear set 4 is a normal simple planetary gear set consisting of a sun gear 4S, a ring gear 4R, a pinion 4P that meshes with these gears, and a carrier 4C that rotatably supports the pinion 4P.
Sun gear 5S, ring gear 5R, pinion 5P
and carrier 5C. Next, the various friction elements mentioned above will be explained. The carrier 4C can be appropriately connected to the input shaft 2 via a high clutch H/C, and the sun gear 4S can be appropriately fixed by a band brake B/B, and can also be appropriately connected to the input shaft 2 by a reverse clutch R/C. . The Carrier 4C can be fixed appropriately with a multi-plate low reverse brake LR/B, and
Reverse rotation (rotation in the opposite direction to the engine) is prevented via the row one-way clutch LO/C. Ring gear 4R is integrally connected to carrier 5C and output shaft 6
The sun gear 5S is coupled to the input shaft 2. Ring gear 5R is an overrun clutch
In addition to being able to connect to carrier 4C as appropriate via OR/C, forward one-way clutch FO/C
and is correlated to the carrier 4C via the forward clutch F/C. The forward one-way clutch FO/C connects the ring gear 5R to the carrier 4C in the reverse direction (the direction opposite to the engine rotation) when the forward clutch F/C is engaged. High clutch H/C, reverse clutch R/
C, low reverse brake LR/B, overrun clutch OR/C and forward clutch F/
C is operated by hydraulic pressure supply to perform the above-mentioned appropriate coupling and fixing, and band brake B/B is connected to 2-speed servo apply chamber 2S/A,
When the 3rd speed servo release chamber 3S/R and the 4th speed servo apply chamber 4S/A are set and the 2nd speed selection pressure P ₂ is supplied to the 2nd speed servo apply chamber 2S/A, the band brake B/B is activated. In this state, when the 3rd speed selection pressure _P3 is also supplied to the 3rd speed servo release chamber 3S/R, the band brake B/B becomes inactive, and then the 4th speed servo apply chamber 4S/A is also supplied with the 3rd speed selection pressure P3.
When the speed selection pressure _P4 is supplied, the band brake B/B is activated. Such a power transmission train includes friction elements B/B, H/
By operating C, F/C, OR/C, LR/B, and R/C in various combinations as shown in the table below,
Together with the appropriate differential of friction elements FO/C and L/C,
By changing the rotational state of the elements constituting the planetary gear sets 4 and 5, it is possible to change the rotational speed of the output side 6 relative to the rotational speed of the input shaft 2, and as shown in the following table, there are four forward speeds and one reverse speed. You can get the gears. Note that in the table below, the ○ mark indicates operation (hydraulic inflow), while the 〓 mark indicates a friction element that should be activated when engine braking is required. Then, while the overrun clutch OR/C is operated, the forward one-way clutch FO/C placed in parallel with it is inactive, and while the low reverse brake LR/B is operated, the forward one-way clutch FO/C is placed in parallel with it, as shown by the mark. Of course, the row one-way clutch LO/C becomes inoperative.

[Table] By the way, the hydraulic side control device shown in FIG. 2 includes a pressure regulator valve 20, a pressure modifier valve 22, and a duty solenoid 2.
4, pilot valve 26, torque converter regulator valve 28, lockup control valve 3
0, shuttle valve 32, duty solenoid 3
4, manual valve 36, first shift valve 38, second
Shift valve 40, first shift solenoid 42, second
Shift solenoid 44, forward clutch control valve 46, 3-2 timing valve 48, 4-
2 relay valve 50, 4-2 sequence valve 52, I
Range pressure reducing valve 54, shuttle valve 56, overrun clutch control valve 58, third shift solenoid 60, overrun clutch pressure reducing valve 63,
The main components are a 2-speed servo apply pressure accumulator 64, a 3-speed servo release pressure accumulator 66, a 4-speed servo apply pressure accumulator 68, which constitutes the main part of the shock reduction device of the present invention, and an accumulator control valve 70. Torque converter 3, forward clutch F/C, high clutch H/C, band brake B/B, reverse clutch R/C low reverse brake LR/B, overrun clutch OR/
C and oil pump O/P as shown in the figure. The pressure regulator valve 20 has a spool 20b elastically supported at the left half position in the figure by a spring 20a.
and the plug 2 that abuts against the lower end surface of the spool in the figure.
Basically, the oil pump O/P regulates the oil discharged to the circuit 71 to a certain pressure determined by the spring force of the spring 20a, but the plug 20c applies an upward force to the spool 20b in the figure. When the line pressure is increased, the above pressure is increased accordingly to reach a predetermined line pressure. For this purpose, the pressure regulator valve 20 is configured to receive the pressure in the circuit 71 via the damping orifice 72 to the pressure receiving surface 20d of the spool 20b, thereby biasing the spool 20b downward. Ports 20e to 20h open and close depending on the stroke position of 20b
will be established. The port 20e is connected to the circuit 71, and is arranged so that as the spool 20b descends from the left half position in the figure, it communicates with the ports 20h and 20f. The port 20f is arranged so that as the spool 20b descends from the left half position in the figure, communication with the port 20g, which is used as a drain port, decreases, and at the point when communication with this is cut off, communication with the port 20e begins. . Then, the port 20f is connected to the capacity control actuator 75 of the oil pump O/P via a circuit 74 having a bleed 73 in the middle. The oil pump O/P is a variable capacity vane pump driven by the engine as described above, and the eccentricity is reduced when the pressure toward the actuator 75 exceeds a certain value, so that the capacity becomes smaller. The plug 20c of the pressure regulator valve 20 receives the modifier pressure from the circuit 76 on its lower end face in the figure, and receives the retreat selection pressure from the circuit 77 on the pressure receiving surface 20i, and the plug 20c receives the modifier pressure from the circuit 77 on its pressure receiving surface 20i, and the plug 20c receives the modifier pressure from the circuit 77 on its lower end face in the figure. Assume that a force of 2 is applied to the spool 20b. The pressure regulator valve 20 is normally in the left half state in the figure, and when oil is discharged from the oil pump O/P, this oil flows into the circuit 71. Circuit 7 at the left half position of spool 20b
The oil in No. 1 is not drained at all, and the pressure increases.
This pressure acts on the pressure receiving surface 20d through the orifice 72, pushes down the spool 20b against the spring 20a, and connects the port 20e to the port 20h. As a result, the above pressure is partially drained from the port 20h and lowered, and the spool 20b is pushed back by the spring 20a. By repeating this action, the pressure regulator valve 20 basically operates in the circuit 71.
The pressure inside (hereinafter referred to as line pressure) is set to a value corresponding to the spring force of the spring 20a. By the way, plug 2
An upward force from the modifier pressure from the circuit 76 acts on 0c, causing the plug 20c to come into contact with the spool 20b as shown in the right half of the figure, and this upward force is applied to the spool 20b to assist the spring 20a, and As will be described later, the modifier pressure is generated when the vehicle is not in reverse mode and increases in proportion to the engine load (engine output torque), so the above-mentioned line pressure increases as the engine load increases other than when the reverse mode is selected. When reversing is selected, an upward force is applied to the plug 20c by the retracting selection pressure (same value as the line pressure) from the circuit 77 instead of the modifier pressure described above, and this is applied to the spool 20b, so that the line pressure is kept at a desired constant value when reversing is selected. becomes. When the oil pump O/P reaches a certain rotational speed or higher (the engine rotates at a certain rotational speed or higher), the oil discharge amount that increases accordingly becomes excessive, and the pressure within the circuit 71 exceeds the pressure regulation value. This pressure lowers the spool 20b further from the pressure regulating position in the right half of the figure, communicates the port 20f with the port 20e, and blocks it from the drain port 20g. As a result, some of the oil in port 20e is removed from port 20f and bleed 73, but feedback pressure is generated within circuit 74. This feedback pressure increases as the rotational speed of the oil pump O/P increases, and reduces the eccentricity (capacity) of the oil pump O/P via the actuator 75. In this way, the capacity of the oil pump O/P is controlled so that the discharge amount remains constant while the rotational speed exceeds a certain value, and the power loss of the engine is prevented from increasing due to discharging more oil than necessary. . As mentioned above, the line pressure generated in the circuit 71 is transferred to the pilot valve 26, the manual valve 36, and the accumulator control valve 70 by the line pressure circuit 78.
and a third-speed servo release pressure accumulator 66. The pilot valve 26 includes a spool 26b elastically supported in the upper half position in the figure by a spring 26a, and the end face of the spool 26b far from the spring 26a is connected to a chamber 26c.
The pilot valve 26 is further provided with a drain port 26d, and a pilot pressure circuit 79 having a strainer S/T is maintained. and,
A communication hole 26e is provided in the spool 26b to guide the pressure of the pilot pressure circuit 79 to the chamber 26c, and the circuit 79 is switched and connected from the circuit 78 to the drain port 26d as it moves to the right in the figure. The pilot valve 26 is normally in the upper half state in the figure, and when it is supplied with line pressure from the circuit 78, it increases the pressure in the circuit 79. The pressure in the circuit 79 reaches the chamber 26c through the communication hole 26e, causing the spool 26b to move to the right in the figure, and when the spool 26b exceeds the pressure regulating position shown in the lower half, the circuit 79 is cut off from the circuit 78, and at the same time, the drain port 26
Leads to d. At this time, the pressure in circuit 79 is reduced,
This pressure drop causes the spool 26b to spring 26a.
When pushed back, the pressure in the circuit 79 rises again. Thus, the pilot valve 26 can reduce the line pressure from the circuit 78 to a constant value determined by the spring force of the spring 26a, and output it to the circuit 79 as pilot pressure. This pilot pressure is applied to the pressure modifier valve 22 and the duty solenoid 2 through a circuit 79.
4, 34, lockup control valve 30, forward clutch control valve 46, shuttle valve 32, first, second, third shift solenoid 4
2, 44, 60, and the shuttle valve 56. The duty solenoid 24 consists of a coil 24a, a spring 24d, and a plunger 24b.
The circuit 81 connected to the pilot pressure circuit 79 via the orifice 80 is turned on (energized) by the coil 24a.
It is assumed that the drain port 24c communicates with the drain port 24c.
This duty solenoid 24 turns on the coil 24a at regular intervals by a computer (not shown).
The circuit 81 is turned OFF, and the ratio of ON time to the constant period (duty ratio) is controlled.
A control pressure is generated in accordance with the duty ratio.
The duty ratio is made smaller as the engine load (for example, engine throttle opening) increases except when the reverse is selected, so that the above-mentioned control pressure is made higher as the engine load increases. Further, when selecting reverse, the duty ratio is set to 100%, and the above control pressure is set to 0. The pressure modifier valve 22 has a spring 22a.
The pressure modifier valve 22 further includes an output port 22c to which the circuit 76 is connected, and an input port to which the pilot pressure circuit 79 is connected. Port 22d and drain port 2
2e is provided, and the spool 22b is far from the spring 22a.
A circuit 76 is connected to the chamber 22f facing the end face. These ports are arranged so that the port 22c is exactly blocked from the ports 22d and 22e at the left half of the spool 22b in the figure. The pressure modifier valve 22 has a spring 22
The spool 22b receives the spring force from a and the force from the control pressure from the circuit 81 downward in the figure, and the spool 22b receives the force due to the output pressure from the port 22c that has reached the chamber 22f upward in the figure. The spool 22b is stroked to a balanced position. If the output pressure from the port 22c is insufficient to match the downward force, the spool 22b descends beyond the pressure regulating position shown in the left half. At this time, the port 22c communicates with the port 22d, and receives supplementary pilot pressure from the circuit 79 to increase the output pressure. Conversely, if this output pressure is too high to match the downward force mentioned above, spool 2
2b rises toward the right half position in the figure. At this time, the port 22c communicates with the drain port 22e, and the output pressure is reduced. By repeating this action, the pressure modifier valve 22 regulates the output pressure from the port 22c to a value corresponding to the sum of the spring force of the spring 22a and the force due to the control pressure from the circuit 81.
This is supplied as a modifier pressure to the plug 20c of the pressure regulator valve 20 from the circuit 76. By the way, as mentioned above, the control pressure increases as the engine load increases except when reverse is selected, and is 0 when reverse is selected, so the modifier pressure is also a value obtained by amplifying this control pressure by the spring force of the spring 22a. It increases as the engine load increases except when the reverse is selected, and becomes 0 when the reverse is selected, allowing the pressure regulator valve 20 to control the line pressure described above. That is, in this embodiment, the line pressure control means is constituted by the duty solenoid 24 as an actuator, the pressure modifier valve 22, and the pressure regulator valve 20. Torque converter regulator valve 28 has spring 2
8a, the spool 28b is elastically supported in the right half position in the figure, and the port 28
c to the port 28d, and as the spool 28b rises from the left half position in the figure, the port 28c
The degree of communication is decreased for port 28d, port 2
It is assumed that the degree of connectivity is increased relative to 8e. In order to control the stroke of the spool 28b, a chamber 28f facing the spool end face far from the spring 28a is communicated with the port 28c through a communication hole 28g provided in the spool 28b. The port 28c is connected to a predetermined lubricating part via a relief valve 82 and connected to the lockup control valve 30 via a circuit 83, and the port 28d is connected to the port 20 of the pressure regulator valve 20 via a circuit 84.
port 28e is connected to lockup control valve 30 by circuit 85. circuit 85
has an orifice 86 in the middle, and connects the orifice and port 28c to a circuit 83 via an orifice 87, and communicates with an oil cooler 89 and a predetermined lubricating section 90 via a circuit 88. The torque converter regulator valve 28 is normally in the right half state in the figure, where oil flows from the port 20h of the pressure regulator valve 20 to the circuit 8.
4, this oil is directed from circuit 83 to torque converter 3 as described below. When supply pressure to the torque converter is generated, this torque converter supply pressure is applied to the communication hole 2.
8g, the chamber 28f is reached, and the spool 28b is raised against the spring 28a in the figure. When the spool 28b rises from the left half position in the figure due to an increase in the torque converter supply pressure, the port 28e opens and a portion of the torque converter supply pressure is removed through the port 28e and the circuit 88, thereby reducing the torque converter supply pressure. The pressure is adjusted to a value determined by the spring force of the spring 28a. The oil removed from the circuit 88 is cooled by an oil cooler 89 and then directed to a lubricating section 90. In addition, the torque converter regulator valve 28
If the torque converter supply pressure exceeds the above value even with the above-mentioned pressure regulating action, the relief valve 82 opens and the excess pressure is released to the corresponding lubricating part, thereby preventing deformation of the torque converter 3. The lock-up control valve 30 is connected to the spool 3
0a and the plug 30b coaxially butted,
When the spool 30a is at the limit position shown in the right half, the circuit 83 is connected to the circuit 91 from the torque converter release chamber 3R, and when the spool 30a is lowered to the left half position in the figure, the circuit 83 is connected to the circuit 85. When the spool 30a further descends, the circuit 91 is connected to the drain port 30c. In order to control the stroke of the spool 30a, the end face of the spool 30a far from the plug 30a faces the chamber 30d, and the orifice 9 is placed in the chamber 30e facing the end face of the plug 30b far from the spool 30a.
2 to lead the pressure of the circuit 91. Note that the circuit 93 from the torque converter apply chamber 3A is connected to the circuit 85 at a location closer to the lockup control valve 30 than the orifice 86. Further, the pilot pressure from the circuit 79 is applied to the plug 30b through the orifice 94 to continue applying a downward force in the figure, thereby preventing pulsation of the spool 30a. The lock-up control valve 30 controls the stroke of the spool 30a by the pressure supplied to the chamber 30d, and while this pressure is sufficiently high, the spool 30a
maintains the right half position in the figure. At this time, the oil from the circuit 83 flows through the circuit 91, the release chamber 3R, the apply chamber 3A, the circuit 93, and the circuit 85 under pressure regulation by the torque converter regulator valve 28.
Excluded from 8. Thus, the torque converter 3 transmits power in the converter state. As the pressure within chamber 30d decreases, spool 30a is forced to close plug 30 by pressure from orifices 92, 94.
b, and further descends from the left half position in the figure, the pressure regulating oil from circuit 83 flows to circuits 85, 93, apply chamber 3A, release chamber 3R, circuit 91, and drain port 30c. As a result, the torque converter 3 transmits power into the chamber 30d under a slip control state in which the slip decreases as the pressure decreases. Room 3 from this state
When the pressure inside 0d is further reduced, the spool 30
Due to the further fall of a, the circuit 91 is connected to the drain port 3.
0c, the pressure in the release chamber 3R becomes 0, and the torque converter 3 transmits power in a locked-up state. The shuttle valve 32 controls the stroke of the lockup control valve 30 together with a forward clutch control valve 46, which will be described later.
A spool 32b is elastically supported by 2a in the lower half position in the figure, and this spool is appropriately switched to the upper half position in the figure by the pressure inside the chamber 32c. The shuttle valve 32 connects the circuit 95 of the chamber 30d to the pilot pressure circuit 7 when the spool 32b is in the lower half position in the figure.
9 and extending from chamber 46a of forward clutch control valve 46.
is connected to a circuit 97 from the duty solenoid 34, and when the spool 32b is in the upper half position in the figure, the circuit 95 is connected to the circuit 97, and the circuit 96 is connected to the circuit 79. The duty solenoid 34 is a plunger 34 elastically supported in the closed position by a coil 34a and a spring 34d.
A circuit 97 connected to the pilot pressure circuit 79 through an orifice 98 is connected to the coil 34a.
When it is ON (energized), it shall be connected to the drain port 34c. This duty solenoid 34 is controlled by a computer (not shown) to turn the coil 34a ON and OFF at a constant cycle, and also controls the ratio of the ON time to the constant cycle (duty ratio), so that a circuit 97 is connected to the coil 34a according to the duty ratio. generates control pressure. When the control pressure of the circuit 97 is used to control the stroke of the lock-up control valve 30 with the shuttle valve 32 in the upper half state in the figure, the duty ratio of the solenoid 34 is determined as follows. In other words, under high load and low rotation speeds of the engine where the torque increasing function and torque fluctuation absorbing function of the torque converter 3 are absolutely necessary, the duty ratio is set to 0.
%, thereby making the control pressure of circuit 97 the same as the pilot pressure of circuit 79, which is the source pressure. At this time, the control pressure maintains the spool 30a in the right half position in the figure in the chamber 30d, and maintains the torque converter 3 in the converter state to meet the above requirements. As the requirements for both of the above functions of the torque converter 3 become lower, the duty ratio is increased and the control pressure is lowered.
The torque converter 3 is operated in a slip control state that matches the demand through The torque converter 3 is maintained in the locked-up state as required via the lock-up control valve 30 by setting the pressure to zero. Note that when the shuttle valve 32 is in the lower half state in the figure and the control pressure of the circuit 97 is used to control the stroke of the forward clutch control valve 46, the duty ratio of the solenoid 34 reduces the N→D selection shock as described later. or to prevent creep. The manual valve 36 is operated by the driver to select parking (P) range, reverse (R) range, neutral (N) range, forward automatic shift (D) range, forward second gear engine brake () range, and first forward gear range. Spool 3 stroked to high speed engine brake () range
6a, and the line circuit 78 is connected to ports 36D and 36 according to the selected range of the spool as shown in the table below.
, 36, 36R. In this table, ○ marks indicate ports that communicate with the line pressure circuit 78, and unmarked ports indicate ports that are drained.

[Table] The first shift valve 38 includes a spool 38b elastically supported in the left half position in the figure by a spring 38a, and this spool is switched to the right half position in the figure when pressure is supplied to the chamber 38c. . When the spool 38b is in the left half position, the first shift valve 38 changes the port 38d to the drain port 38e and the port 38f to the drain port 38e.
to port 38g, port 38h to port 38i
When the spool 38b is in the right half position in the figure, the port 38d is connected to the port 38j, and the port 3 is connected to the port 38j.
8f to port 38k, port 38h to port 3
8l each. The second shift valve 40 includes a spool 40b elastically supported by a spring 40a in the left half position in the figure, and this spool assumes the right half position in the figure when pressure is supplied to the chamber 40c. and second shift valve 40
When the spool 40b is in the left half position in the figure, the port 40d is connected to the drain port 40e, the port 40f is connected to the port 40g, and the port 40h is connected to the drain port 40i with an orifice, and the spool 40
When b is in the right half position in the figure, port 40d is connected to port 4.
0j, port 40f to drain port 40e,
It is assumed that each port 40h is connected to a port 40k. The spool positions of the first and second shift valves 38 and 40 are controlled by a first shift solenoid 42 and a second shift solenoid 44, respectively, and these shift solenoids are connected to coils 42a and 44a, respectively.
and plungers 42b, 44b, spring 42
d, 44d. 1st shift solenoid 4
2 is connected to the pilot pressure circuit 79 via the orifice 99, and connects the circuit 100 to the chamber 38c.
Drain port 42 when coil 42a is ON (energized)
c, the control pressure in the circuit 100 is set to the same value as the pilot pressure which is the source pressure, and the first shift valve 38 is thereby switched to the right half state in the figure. Further, the second shift solenoid 44 is connected to the pilot pressure circuit 79 via the orifice 101, and the circuit 102 leading to the chamber 40c is connected to the coil 44a.
When turned on (energized), the drain port 44c is shut off to make the control pressure in the circuit 102 the same value as the original pilot pressure, thereby switching the second shift valve 40 to the right half state in the figure. Turn on these shift solenoids 42 and 44,
The first to fourth forward speeds can be obtained by combinations of the OFF states and, therefore, the states of the shift valves 38 and 40, which are summarized in the table below.

[Table] In this table, the ○ marks indicate the right half of the shift valve in the figure (ascending), the × marks indicate the left half of the shift valve in the figure (descending), and the shift solenoid 42,
A computer (not shown) determines a suitable gear position based on the vehicle speed and engine load based on a predetermined gear shift pattern, and determines whether to turn on or off 44 in accordance with this gear position. The forward clutch control valve 46 includes a spool 46b on which the pilot pressure from the circuit 79 guided through the orifice 103 is applied downward in the figure to prevent pulsation of the spool, and further includes a orifice 10
4, the operating pressure of the forward clutch F/C in the circuit 105 is fed back and applied downward in the figure. The spool 46b is stroked to a position where the downward force in the figure due to these pressures and the force due to the pressure inside the chamber 46a are balanced.
When the spool 46b is in the right half position in the figure, the circuit 105
is connected to the drain boat 46c, and in the left half position in the figure, the circuit 105 is connected to the circuit 106, and the circuit 105 has a one-way orifice 107 that exerts a throttling effect only on the hydraulic pressure directed to the forward clutch F/C. The circuit 106 is connected to the port 36D of the manual valve 36. 3-2 The timing valve 48 includes a spool 48b elastically supported at the left half position in the figure by a spring 48a. At this spool position, a port 48c and a port 48d with an orifice 48f communicate with each other, and the chamber 48
It is assumed that when the pressure in e is high and the spool 48b is at the right half position in the figure, the ports 48c and 48d are shut off. 4-2 The relay valve 50 includes a spool 50b elastically supported at the left half position in the figure by a spring 50a, and at this spool position, the port 50c is connected to the drain port 50d with an orifice, and pressure is supplied into the chamber 50e. It is assumed that when the spool 50b is at the right half position in the figure, the port 50c communicates with the port 50f. 4-2 The sequence valve 52 includes a spool 52b elastically supported in the right half position in the figure by a spring 52a, and in this spool position, the port 52c is connected to the drain port 52d with an orifice, and the pressure inside the chamber 52e is high and the spool is closed. It is assumed that when 52b is in the left half position in the figure, port 52c communicates with port 52f. The range pressure reducing valve 54 includes a spool 54b biased toward the right half position in the figure by a spring 54a, and a port 54c, which communicates with each other at this spool position.
54d, and a drain port 54e that begins to communicate with the port 54c when the spool 54b rises to the left half position in the figure and finishes closing the port 54d. A chamber 54f facing the end face of the spool 54b far from the spring 54a is connected to the port 54c via an orifice 108. Thus, the range pressure reducing valve 5
4 is normally in the right half state in the figure, and when pressure is supplied to the port 54d, pressure is output from the port 54c. This output pressure is the orifice 108
The pressure is applied to the lower end surface of the spool 54b in the figure, and as the output pressure increases, the spool 54b is raised in the figure. When the spool 54b rises above the left half position in the figure, the port 54c communicates with the drain port 54e and reduces the output pressure from the port 54c.
When the spool 54b is lowered by more than the left half position in the figure due to this output pressure drop, the port 54c is changed to the port 5.
4d and increases the output pressure from port 54c. By repeating this action, the output pressure from the port 54c is reduced to a constant value determined by the spring force of the spring 54a. The shuttle valve 56 includes a spool 56b elastically supported in the left half position in the figure by a spring 56a, and this spool is held in this position when pressure is supplied to the chamber 56g; When the upward force in the figure due to the pressure from the port 56c exceeds a certain value, it is stroked to the right half position in the figure. Port 56d is connected to the circuit 109 from the third shift solenoid 60 at the left half position in the figure, and port 56e is connected to the drain port 56f, and port 56d is connected to the pilot pressure circuit 79 at the right half position in the figure. 56e is connected to the circuit 109. The third shift solenoid 60 includes a coil 60a, a plunger 60b, and a spring 60d.
Pilot pressure circuit 79 via orifice 110
Turn on the circuit 109 connected to the coil 60a.
(When energized), the drain port 60c is cut off, and the control pressure in the circuit 109 is set to the same value as the pilot pressure, which is the source pressure. Note that whether the third shift solenoid 60 is turned on or off is determined by a computer (not shown). It is assumed that the overrun clutch control valve 58 includes a spool 58b elastically supported in the left half position in the figure by a spring 58a, and this spool is switched to the right half position in the figure when pressure is supplied to the chamber 58c. In addition, the spool 58b is located at the left half position in the figure, and the port 58d is connected to the drain port 58e, and the port 58f is connected to the drain port 58e.
are connected to the port 58g, and at the right half position in the figure, the port 58d is connected to the port 58h, and the port 58f is connected to the drain port 58e. The overrun clutch pressure reducing valve 62 has a spring 62a.
The spool 62 is supported in the left half position in the figure by
b, and when there is pressure on this spool from port 62c, this applies a downward force in the figure to hold spool 62b in this position. While there is no pressure inflow from port 62c, port 62c
When pressure is supplied to d, this pressure is applied to port 62
Increase the output pressure from e. This output pressure is in the chamber 62f
When the spool 62b is fed back to a value corresponding to the spring force of the spring 62a, the spool 62b is moved to the right half position in the figure, and the ports 62d and 62e are cut off.
The overrun clutch pressure reducing valve 62 is connected to the port 62e.
It is assumed that the output pressure from the spring 62a is reduced to a constant value determined by the spring force of the spring 62a. The 2-speed servo apply pressure accumulator 64 is constructed by elastically supporting a stepped piston 64a at the left half position in the figure by a spring 64b, and a chamber 64c defined between both ends of the stepped piston 64a is opened to the atmosphere. The small-diameter end face and large-diameter end face of the piston with
4d, 64c. The 3-speed servo release pressure accumulator 66 includes a stepped piston 66a elastically supported in the left half position in the figure by a spring 66b, and a chamber 66c defined between both ends of the stepped piston is connected to the line pressure circuit 78. The small-diameter end face and large-diameter end face of the stepped piston face the closed chambers 66d and 66e, respectively. The 4-speed servo apply pressure accumulator 68 is constructed by elastically supporting a stepped piston 68a at the left half position in the figure by a spring 68b, and defines a sealed chamber 68c between both ends of the stepped piston. The small diameter end face and the large diameter end face are sealed in sealed chambers 68d and 68, respectively.
Let's face e. Accumulator control valve 70 has spring 70
The spool 7 is supported in the left half position in the figure by a.
0b, and the spool 70b is remote from the spring 70a.
The control pressure of the circuit 81 is introduced into the chamber 70c facing the end face of the circuit 81. The spool 70b connects the output port 70d to the drain port 70e at the left half position in the figure, and the spool 70b connects the output port 70d to the drain port 70e, and
When the control pressure increases and the spool 70b rises above the right half position in the figure, the port 70d is switched and connected to the line pressure circuit 78. and,
The output port 70d is connected to the accumulator chambers 64d and 68c by the circuit 111, and the spring 70
It is also connected to the chamber 70f that accommodates a. Thus, the accumulator control valve 70 raises the spool 70b above the right half position in the drawing by the control pressure applied to the chamber 70c except when the reverse movement is selected. As a result, the line pressure from the circuit 78 is output to the circuit 111, and when the pressure in the circuit 111 reaches a value corresponding to the control pressure, the spool 70b is elastically supported at the right half position in the figure. This is why circuit 11
The pressure of 1 is regulated to a value corresponding to the control pressure, but
Since the control pressure increases as the engine load (engine output torque) increases except when reverse is selected as described above, the accumulators 64 and 68 are removed from the circuit 111.
The pressure supplied to the chambers 64d and 68c as accumulator back pressure also increases as the engine output torque increases. In addition, since the control pressure is 0 when the reverse movement is selected, no pressure is output to the circuit 111. Next, to provide a supplementary explanation of the hydraulic circuit network, the circuit 106 extending from the port 36D of the manual valve 36 connects the port 38g of the first shift valve 38 and the second port 38g of the first shift valve 38.
While connecting to port 40g of shift valve 40,
It is also connected to port 56c of shuttle valve 56 and port 58g of overrun clutch control valve 58 via circuit 112 branched from circuit 106. The port 38f of the first shift valve 38 is connected to the circuit 11
3 to the port 50f of the 4-2 relay valve 50, and also to the accumulator chamber 64e and the 2-speed servo apply chamber 2S/A via the one-way orifice 114, and the port 50f is connected to the port 50f of the 4-2 relay valve 50 through the one-way orifice 114.
15, it is also connected to the chamber 32c of the shuttle valve 32. Furthermore, the port 38h of the first shift valve 38 is connected to the chamber 50e of the 4-2 relay valve 50 and the port 58h of the overrun clutch control valve 58 by a circuit 116, and the port 50c of the 4-2 relay valve 50 is connected to the chamber 50e of the 4-2 relay valve 50 by a circuit 117. Connected to port 40k of 2-shift valve 40. The ports 38k and 38l of the first shift valve 38 are connected to the port 4 of the second shift valve 40.
High clutch H/C by circuit 118 along with 0f
A pair of one-way orifices 119 and 120 arranged in opposite directions are inserted in the middle. A circuit 121 branched from the circuit 118 between these orifices and the high clutch H/C
is connected to the 3-speed servo release chamber 3S/R and the accumulator chamber 66 via the one-way orifice 122.
ports 48c and 48d are connected to the circuit 123 that bypasses the one-way orifice 122, and the 3-2 timing valve 48 is connected to the circuit 123 that bypasses the one-way orifice 122.
Insert into 3. Circuit 1 between one-way orifice 122 and 3 servo release chambers 3S/R
21 is connected to the chamber 52e of the 4-2 sequence valve 52, and the ports 52c and 52f of the 4-2 sequence valve 52 are connected to the port 38i of the first shift valve 38 and the port 40h of the second shift valve 40, respectively. Connect to. Port 38j of first shift valve 38 is connected to circuit 125
The port 38d is connected to the port 40d of the second shift valve 40 by the circuit 126, and the port 38d is connected to one inlet port of the shuttle ball 127 by the circuit 126. The other inlet port of shuttle ball 127 is connected to circuit 12.
8 is connected to the port 36R of the manual valve 36 together with the circuit 77 on the one hand, and to the reverse clutch R/C and the accumulator chamber 68d via the one-way orifice 129 on the other hand, and the outlet port of the shuttle ball 127 is connected to the port 36R of the manual valve 36 through the circuit 130. Connect to low reverse brake LR/B.
The port 40j of the second shift valve 40 is connected to the port 54c of the range pressure reducing valve 54 and the chamber 5 by the circuit 131.
4f and the port 54 of the range pressure reducing valve 54.
d is connected to port 36 of manual valve 36 by circuit 132. Port 56e of shuttle valve 56 is connected by circuit 133 to chamber 48e of 3-2 timing valve 48, and port 56d is connected by circuit 134 to chamber 58e of overrun clutch control valve 58. Overrun clutch control valve 58
The port 58d is connected to the accumulator chamber 66d by a circuit 135, and also connected to the accumulator chamber 68e and the 4-speed servo apply chamber 4S/A via a one-way orifice 136. Port 58f of overrun clutch control valve 58 is connected to port 62d of overrun clutch pressure reducing valve 62 by circuit 137, port 62e of pressure reducing valve 62 is connected to overrun clutch OR/C by circuit 137, and port 62e of overrun clutch pressure reducing valve 62 is connected to overrun clutch OR/C by circuit 137. ，
A check valve 139 is provided between 138 and 138. Port 62c of overrun clutch pressure reducing valve 62 is connected to port 36 of manual valve 36 by circuit 140.
and connected to the chamber 56g of the shuttle valve 56. The operation of the hydraulic circuit in the forward travel range will now be described. Pressure regulator valve 20, pressure modifier valve 22, and duty solenoid 2
4 uses the above-mentioned action to adjust the oil from the oil pump O/P to a line pressure that increases in proportion to the engine output torque except when selecting reverse, and keeps the oil from the oil pump O/P at a constant value when selecting reverse;
This is output to the circuit 78. This line pressure reaches the pilot valve 26, manual valve 36, accumulator control valve 70, and accumulator 66, and places the accumulator 66 in the right half state in the figure. Accumulator control valve 7
0, the accumulator back pressure proportional to the engine output torque is applied to the chambers 64d,
68c, and these accumulators are placed in the right half state in the figure. In addition, when the reverse is selected, the accumulator control valve 70 sets the accumulator back pressure to 0 as described above, and the accumulator 64,
68 is shown in the left half state in the figure. Further, the pilot valve 26 always outputs a constant pilot pressure to the circuit 79 due to the above-mentioned action. P, N range The driver does not wish to drive and sets manual valve 36 to P.
Or, if the N range is selected, all manual valve ports 36D, 36, 36, and 36R become drain ports as shown in Table 2 above, and line pressure is not output from these ports, so the line from these ports is Forward clutch F/C, high clutch H/
C, band brake B/B, reverse clutch R/C, low reverse brake LR/B, and overrun clutch OR/C are all kept inoperative, leaving the power transmission train in Figure 2 in a neutral state where no power can be transmitted. You can keep it. D Range When forward travel is desired and the manual valve 36 is set to the D range, automatic gear shifting is performed as follows. (First speed) That is, in the D range, the manual valve 36 outputs the line pressure from the circuit 78 to the port 36D as shown in Table 2 above. The line pressure from port 36D is supplied as D range pressure by circuit 106 to port 38g of first shift valve 38, port 40g of second shift valve 40, and forward clutch control valve 46, and is supplied by circuit 112 to port 38g of first shift valve 38, port 40g of second shift valve 40, and forward clutch control valve 46, and is supplied by circuit 112 to port 38g of first shift valve 38, port 40g of second shift valve 40, and forward clutch control valve 46. 56 and port 58g of the overrun clutch control valve 58. On the other hand, when the vehicle is stopped in the D range, the computer turns on both the first shift solenoid 42 and the second shift solenoid 44, and the first shift valve 38
Both the second shift valve 40 and the second shift valve 40 are in the right half state in the figure. Therefore, the high clutch H/C is communicated from the circuit 118 through the port 40f to the drain port 40e and becomes inoperable. Also, 2-speed servo apply chamber 2S/
A is connected to drain port 40e from circuit 113 through ports 38f and 38k, circuit 118, and port 40f.
The 3rd speed servo release chamber 3S/R is connected to circuit 1.
21, 118, and ports 40f to the drain port 40e, and the 4-speed servo apply chamber 4S/A communicates with the same drain port 40e as shown below, so the band brake B/B is also inoperative. That is, while the engine output torque is above a certain level, the D range pressure (line pressure) from the port 56c, which is proportionally high, causes the shuttle valve 56 to be in the right half state in the figure, and the overrun clutch control valve 58 is output from the circuit 134. supplying the pilot pressure of circuit 79 to
This valve is placed in the right half state in the figure. Further, even if the engine output torque is below a certain level and the shuttle valve 56 is in the left half state in the figure, if there is no engine brake request operation, which will be described later, then the control is directed from the circuit 109 to the overrun clutch control valve 58 via the circuit 134. The computer sets the pressure to the same value as the pilot pressure by turning on the third shift solenoid 60, and sets the overrun clutch control valve 58 to the right half state in the figure. Therefore, at this time, the 4th speed servo apply pressure 4S/A is connected to circuit 135, port 58.
d, 58h, circuit 116, port 38h, 38
1, the circuit 118, and the port 40f to the drain port 40e as described above. Further, the reverse clutch R/C is drained from the port 36R via the circuit 128 and is in an inoperative state, and the low reverse brake LR/B is also drained in the following manner and is in an inoperative state. That is, one inlet circuit 128 connected to the shuttle ball 127 related to the circuit 130 to the low reverse brake LR/B is drained as described above, and the other circuit 128 is drained as described above.
6, ports 38d, 38j, circuit 12
5. The range pressure reducing valve 54 connected via the ports 40d and 40f and the circuit 131 is connected to the manual valve port 3.
Since it is not receiving pressure supply from port 6, it is in the right half state in the figure and is drained from port 36, so low reverse brake LR/B is in an inoperative state as described above. Next, since the overrun clutch control valve 58 is in the right half state in the figure as described above, the overrun clutch OR/C is connected from the circuit 138 to the drain port 58e via the check valve 139 and the port 58f, and is in an inoperative state. It is. Then, as mentioned above, the 2-speed servo apply chamber
Since there is no pressure in the circuit 113 going to 2S/A,
The shuttle valve 32, which has the chamber 32c connected to this circuit via the circuit 115, is in the lower half state in the figure. Therefore, the shuttle valve 32 supplies the pilot pressure from the circuit 79 to the chamber 30d from the circuit 95, keeps the lockup control valve 30 in the right half state in the drawing, and puts the torque converter 3 in the converter state.
The shuttle valve 32 further supplies the control pressure from the circuit 97 to the chamber 46a from the circuit 96, and adjusts this control pressure to an appropriate value by controlling the duty of the solenoid 34.
can be controlled as follows. That is, in the D range and in the state where no start operation (operation of releasing the brake and depressing the accelerator pedal when the vehicle speed is 0) is performed, the duty ratio of the solenoid 34 is set to 100% and the control pressure to the chamber 46a is applied. Set to 0. As a result, the forward clutch control valve 46 is in the right half state in the figure, and even though the D range pressure is output to the circuit 106 as described above,
This does not reach the forward clutch F/C and keeps it inactive. And high clutch H/C,
Band brake B/B, reverse clutch R/
Since C, low reverse brake LR/B, and overrun clutch OR/C are also inactive as mentioned above, the automatic transmission will remain in a neutral state in which power cannot be transmitted unless a starting operation is performed even in D range. It is possible to prevent the creep phenomenon and the selection shock (N→D selection shock) when switching from the N range to the D range. When the driver performs a start operation, the computer gradually decreases the duty ratio of the solenoid 34 until it finally reaches 0%. As a result, the control pressure to the chamber 46a gradually increases and finally reaches the same value as the pilot pressure of the circuit 79, which is the source pressure. During this time, the forward clutch control valve 46 gradually switches from the right half state in the figure to the left half state in the figure, gradually increasing the pressure from the circuit 105 to the forward clutch F/C,
Ultimately, it becomes the same value as the D range pressure (line pressure) from the circuit 106. Therefore, the forward clutch F/C is gradually operated, and as shown in Table 1 above, in conjunction with the operation of the forward one-way clutch FO/C and the row one-way clutch LO/C, the automatic transmission is brought into the first gear selection state. The vehicle can then be started. During this start, in order to gradually increase the hydraulic pressure of the forward clutch F/C as described above, and in conjunction with the throttling effect of the one-way orifice 107, the forward clutch F/C
The operation of C proceeds at a predetermined speed and can prevent a starting shock. (Second speed) When the vehicle speed increases and the driving state becomes such that the second speed should be selected, the computer switches the first shift solenoid 42 to OFF and closes the first shift valve 38 as shown in Table 3 above. Switch to the left half state in the figure. This causes the first shift valve 38 to
continues to drain through drain port 38e, and connects circuit 116 to ports 38h, 38i and 4-
Drainage is continued by communicating with the drain port 52d through the port 52c of the 2-sequence valve 52 (this valve is in the right half state in the figure because no pressure is currently supplied to the 3-speed servo release chamber 3S/R). However, the first shift valve 38 connects the circuit 113 to the circuit 106, and also supplies the D range pressure to the second speed servo apply chamber 2S/A through the circuit 113, and operates the band brake B/B. As is clear from Table 1 above, the automatic transmission maintains the operation of the forward clutch F/C and operates the forward one-way clutch FO/C.
It becomes a fast selection state. During this upshift from 1st speed to 2nd speed, the hydraulic pressure to the 2nd speed servo apply chamber 2S/A is throttled by the one-way orifice 114, and the accumulator piston 64a located at the right half position in the figure as described above is Since the band brake B/B gradually rises while being pushed, the operation of the band brake B/B proceeds gradually, and the shock during the gear change can be alleviated. Since the back pressure in the chamber 64d applied to the accumulator piston 64a is proportional to the engine output torque as described above, the above-mentioned shift shock reduction effect can be reliably achieved. Furthermore, as is clear from Table 1 above, not only the 2nd speed but also the 3rd and 4th speeds are selected, the D range pressure is supplied to the 2nd speed servo apply chamber 2S/A. The shuttle valve 32, which is supplied to the chamber 32c by the circuit 115, maintains the upper half state in the figure while the second to fourth speeds are selected. As a result, the forward clutch control valve 46 is supplied with the pilot pressure from the circuit 79 to the chamber 46a, and maintains the left half state in the figure, and the forward clutch F/C is fully activated without performing the pressure regulating action. By keeping it, it is not possible to prevent the second to fourth speeds from being selected.
On the other hand, the chamber 30 of the lock-up control valve 30
The control pressure of the circuit 97 is supplied to d, and this control pressure is applied to the duty solenoid 34 by a computer.
By making the determination as described above, the lockup control valve 30 can put the torque converter 3 into the converter state, slip control state, or lockup state to match the operating conditions. (3rd gear) After that, when the driving condition comes to select 3rd gear,
The computer also turns off the second shift solenoid 44 as shown in Table 3 above to place the second shift valve 40 in the left half state in the figure. This allows port 40g
The D range pressure that had reached port 40f, circuit 1
18, it passes through the one-way orifice 120, and is then squeezed by the one-way orifice 119 and supplied to the high clutch H/C, which is operated. On the other hand, this pressure is passed through a circuit 121 branched from the circuit 118 to the one-way orifice 12.
2 and reaches the 3rd speed servo release chamber 3S/R, which deactivates the band brake B/B.
Pressure to 3rd speed servo release chamber 3S/R is 4-2
With respect to the chamber 52e of the sequence valve 52, the valve is placed in the left half state in the figure, and the port 52c is connected to the port 52.
Even though the second shift valve 40 connects this port 52f to the drain port 40i, the circuit 116 continues to drain. Therefore, the high clutch H/C is activated and the band brake B/B is deactivated, and as is clear from Table 1 above, the automatic transmission is activated in conjunction with the forward one-way clutch FO/C. Three speeds can be selected. In addition, during this upshift from 2nd speed to 3rd speed, the pressure to the high clutch H/C and 3rd speed servo release chamber 3S/R is throttled by the one-way orifice 119, and the right half state in the figure is changed as described above. The accumulator piston 66a is inserted into the chamber 66.
Since it rises while being pushed away against the line pressure in c, it is possible to prevent a shock during the gear shift. (4th gear) After that, when the driving condition comes to select 4th gear,
The computer turns on the first shift solenoid 42 as shown in Table 3 above, and switches the first shift valve 38 to the right half state in the figure. The first shift valve 38, which is good for this purpose, cuts off the circuit 113 to the second speed servo apply chamber 2S/A from the D range pressure circuit 106, but communicates with the circuit 118 at the port 38k, and
While continuing to supply D range pressure to the speed servo apply chamber 2S/A, the circuit 126 is connected to the drain port 3.
8e, the circuit 126 continues to drain by communicating with the circuit 125 at the port 38j, and through this to the drain port 40e.
The first shift valve 38 further connects the circuit 116 to the circuit 118 via ports 38h and 38l, and connects the circuit 11
8,116, ports 58h, 58d, circuit 13
5. By supplying D range pressure to the 4-speed servo apply chamber 4S/A via the one-way orifice 136, the band brake B/B is switched to the operating state, and the operation of the forward clutch F/C and high clutch H/C is maintained. In combination with this, the automatic transmission can be brought into the fourth speed selection state as shown in Table 1 above. Note that during this upshift from 3rd speed to 4th speed, the 4th speed selection pressure (highest speed selection pressure) to the 4th speed servo apply chamber 4S/A is throttled by the one-way orifice 136, and as shown in the figure above. The accumulator piston 68a in the middle right half state is moved to the chamber 68.
Since it gradually rises while pushing away against the back pressure in c, it is possible to prevent a shock during the gear change. Since the back pressure in the chamber 68c applied to the accumulator piston 68a is proportional to the engine output torque as described above, the above-mentioned shift shock reduction effect can be reliably achieved. Further, the pressure (fourth speed selection pressure) supplied to the fourth speed servo apply chamber 4S/A reaches the chamber 66d of the accumulator 66. Thus, the capacity of the accumulator 66 at the time of upshifting from the second speed to the fourth speed can be made different from the capacity of the accumulator 66 at the time of the upshifting from the second speed to the third speed to meet the requirements. As a result, the shift shock reduction effect can be appropriately performed even in the jump shift. (4→3 downshift) During the selection of the 4th speed, when the operating state becomes such that the 3rd speed should be selected, the computer turns off the first shift solenoid 42 and the first shift valve 38, as is clear from Table 3 above. Switch to the left half state in the figure. This results in the same state as when selecting the third speed,
The pressure in the 4th speed servo apply chamber 4S/A passes through the one-way orifice 136 and is immediately removed from the drain port 40i, allowing a downshift to the 3rd speed. (4 → 2 downshift) When the operating state becomes such that 2nd speed should be selected while 4th speed is being selected, the computer turns off the first shift solenoid 42 and shifts the
The shift valve 38 is switched to the left half state in the figure, and the second shift solenoid 44 is turned on to switch the second shift valve 40 to the right half state in the figure. By switching the first shift valve 38, the 2nd speed servo apply chamber
Circuit 113 to 2S/A is from circuit 118 to circuit 1
The connection to 06 is changed and pressure is subsequently supplied to the 2-speed servo apply chamber 2S/A. Further, by switching the second shift valve 40, the circuit 118 is cut off from the D range pressure circuit 106 and communicated with the drain port 40e. Therefore, the operating pressure of the high clutch H/C passes through the one-way orifice 119, is throttled by the one-way orifice 120, and is removed from the drain port 40e through the circuit 118.
The pressure in the quick servo release chamber 3S/R is also throttled by the one-way orifice 122 and then removed through the same route. By the way, 3 speed servo release room
The 4-2 sequence valve 52, which receives the pressure of 3S/R through the circuit 124 and responds to it, remains in the left half state in the figure until the pressure is released, and the port 3
Port 5 connected to circuit 116 via 8i, 38h
2c from drain port 52d and connect port 5.
Continue to lead to 2f. Therefore, the pressure in the 4-speed servo apply chamber 4S/A connected to the circuit 116 is not removed, but is maintained until the pressure in the 3-speed servo release chamber 3S/R is completely released. During this time, the pressure in the 4-speed servo apply chamber 4S/A flows through the circuit 116 to the 4-
2 relay valve 50 and maintains this valve in the right half state in the figure. Therefore, the 2-speed servo apply chamber
The pressure in circuit 113 to 2S/A is at port 50f,
50c, circuit 117, ports 40k, 40h, 5
2f, 52c, 38i, 38h and circuit 116,
The pressure inside the 4-speed servo apply chamber 4S/A is maintained through the ports 58h, 58d and the circuit 135. When the pressure in the 3rd speed servo release chamber 3S/R is released, the 4-2 sequence valve 52 changes to the right half state in the figure, and the port 52c is connected to the drain port 52d, and the 4th speed servo apply chamber connected to the circuit 116.
The pressure inside 4S/A is removed from the drain port 52d. As a result of this removal, the 4-2 relay valve 50 enters the left half state in the figure, and removes the pressure in the circuit 117 from the drain port 50d. Thus, during the gear shift, the pressure in the 4th gear servo apply chamber 4S/A is:
The pressure in the 3rd speed servo release chamber 3S/R and the high clutch H/C will be removed after they are released, and the pressure in the former will be released before the pressure in the latter, resulting in 4→
It is possible to prevent gear shifting from 3 to 2 and reliably shift from 4 to 2. (3→2 downshift) When the operating state in which the 2nd speed should be selected is reached in the 3rd speed selection state, the computer activates the 2nd shift solenoid 44 as is clear from Table 3 above.
ON to switch the second shift valve 40 to the right half state in the figure. Due to this switching, even if port 40h is connected from drain port 40i to port 40k, circuit 116 (4th speed servo apply chamber) is connected at 3rd speed.
4S/A) is in the no-pressure state, the 4-2 relay valve 50 is in the left half state in the figure, and the circuit 117 is connected to the drain port 50d, so the port 52f becomes the drain port, and the 4-2 sequence valve 52 Regardless of the condition, the 4-speed servo apply chamber 4S/
Keep A in an unpressurized state. On the other hand, the above switching of the second shift valve 40 is performed by circuit 1.
18 and connect it to the drain port 40e, and connect it to the high clutch H/C and 3-speed servo release chamber 3S/
The pressure in R is removed through the above-mentioned route during the 4-2 gear shift. Therefore, a downshift from 3rd speed to 2nd speed can be obtained, but at this time, the pressure in the 3rd speed servo release chamber 3S/R is removed at a predetermined timing according to the engine operating condition as shown below. , allowing smooth gear shifting. In other words, when the engine output torque is below a certain level,
The D range pressure (line pressure) from the low port 56c corresponding to this puts the shuttle valve 56 in the left half state in the figure, and the chamber 48e of the 3-2 timing valve 48 passes through the circuit 133 and the port 56e to the drain port 5.
6f, the 3-2 timing valve 48 is in the left half state in the figure. Therefore, under this low engine output torque, the 3rd speed servo release chamber 3S/
In addition to the one-way orifice 122, the pressure of R is
It is pulled out even after passing through the orifice 48f, and the pulling out speed is fast. When the engine output torque is above a certain level, the corresponding high D range pressure (line pressure) from the port 56c puts the shuttle valve 56 in the right half state in the figure, and the 3-2 timing valve 48 is in the circuit 109.
The state is changed by the control pressure from. The computer turns on the third shift solenoid 60 under this engine output torque and at a predetermined vehicle speed,
Set the control pressure to the same value as the pilot pressure, which is the source pressure. Therefore, the 3-2 timing valve 48 is in the right half state in the figure, and the pressure release speed of the 3rd speed servo release chamber 3S/R is made low by the one-way orifice 122 alone. (2→1 downshift shift) When the operating state is reached in which the first speed should be selected in the second speed selection state, the computer turns on the first shift solenoid 42 and the first shift valve 38 as shown in Table 3 above. Switch to the right half state in the figure. As a result, the circuit 113 to the second-speed servo apply chamber 2S/A is cut off from the D range pressure circuit 106 and communicates with the circuit 118 via ports 38f and 38k. However, since the circuit 118 is connected to the drain port 40e by the second shift valve 40,
The pressure in the second speed servo apply chamber 2S/A passes through the one-way orifice 114 and is quickly removed, making it possible to downshift from the second speed to the first speed. Range If the driver desires engine braking in 2nd speed and sets the manual valve 36 to the manual range, this manual valve will not only operate from the port 36D but also from the port 36 as shown in Table 2 above. Outputs the line pressure of circuit 78.
Pressure is supplied from the port 36D through the same route as in the case of the D range described above, and the computer shifts the first and second shift solenoids 42 and 44 to the first or second speed according to Table 3 above. By turning the switch ON and OFF to obtain the following, the automatic transmission can be shifted between the first speed and the second speed. The pressure (range pressure) from the manual valve port 36 passes through the circuit 140 and reaches the port 62c of the overrun clutch pressure reducing valve 62, placing this valve in the left half state in the figure. The range pressure from circuit 140 further reaches chamber 56g of shuttle valve 56, locking this valve in the left half position in the figure. Shuttle valve 5
6, the control pressure of the circuit 110 is supplied to the chamber 58c of the overrun clutch control valve 58, and the computer uses this control pressure to turn off the third shift solenoid 60 while selecting the second gear.
, and the overrun clutch control valve 58 is placed in the left half state in the figure. Thus, the D range pressure from circuit 112 is transferred to circuit 13.
7. Overrun clutch pressure reducing valve 62 and circuit 1
38, it is supplied to the overrun clutch OR/C as a friction element, which is actuated to enable engine braking in second gear. For example, this engine brake is applied when selecting range from D range 4th gear,
It works when selecting from range 3rd gear to range. At this time, the overrun clutch pressure reducing valve 62
As mentioned above, since it is in the locked state, no pressure reduction is performed, and the D range pressure, that is, the line pressure, is supplied to the overrun clutch OR/C, and the line pressure is used as the backup pressure. Range When the driver desires engine braking driving in 1st gear and sets the manual valve 36 to range,
This manual valve has port 36 as shown in Table 2 above.
The line pressure of the circuit 78 is output to D, 36, 36. Pressure is supplied from the port 36D through the same route as in the case of the D range described above, and the computer operates the first and second shift solenoids 42,
The automatic transmission can be shifted between the first speed and the second speed by turning ON and OFF 44 so as to obtain the first speed or the second speed according to Table 3 above. The reason why 2nd gear is sometimes selected regardless of the range is because when the engine is reversely driven from the wheels when the range is set while driving, the engine may over-rev at high vehicle speeds. In order to prevent this, under such conditions, the second gear is first set, and then the first gear is set at a vehicle speed that does not cause overspeeding of the engine. The pressure from the manual valve port 36 is maintained by keeping the shuttle valve 56 and overrun clutch pressure reducing valve 62 in the left half state in the figure, as in the case of the range described above, and controlling the overrun clutch control valve 58 by controlling pressure from the circuit 109. The state is changed by By the way, the computer uses this control pressure to control the third shift solenoid 60 in the range concerned.
OFF to 0, the overrun clutch control valve 58 is held in the left half state in the figure, and the overrun clutch OR/C continues to operate. Pressure from manual valve port 36 is in circuit 1
32 and reaches the range pressure reducing valve 54, which reduces the pressure from the circuit 132 to a constant value by the above action and outputs it to the circuit 131. By the way, the second shift valve 40 is in the right half state in the figure as shown in Table 3, regardless of whether it is in the first speed or the second speed, and outputs the pressure of the circuit 131 to the circuit 125. On the other hand, the first shift valve 38 is in the left half state in the figure as shown in Table 3 at the second speed, cutting off the pressure in the circuit 125 and communicating the circuit 126 to the drain port 38e. Thus, the circuit 130 to the low reverse brake LR/B is connected to the shuttle ball 125 and the circuit 125.
The low reverse brake LR/B is inactive. Therefore, operation of the overrun clutch OR/C enables engine braking in second gear. When the vehicle speed reaches a point where the engine does not overspeed even in the first gear, the first gear is entered as described above. In this first gear, the first shift valve 38 is in the right half state in the figure, and the circuit 125 is connected to the circuit 125. 126, circuit 12
5 is supplied to the low reverse brake LR/B via circuit 126, shuttle ball 127, and circuit 130 to operate it. Thus,
Coupled with the fact that the overrun clutch OR/C is activated as described above, it is possible to run with engine braking in first gear. Note that during engine braking in 1st and 2nd speeds, the overrun clutch pressure reducing valve 62 is locked in the left half state in the figure as described above, so it does not perform any pressure reducing action and the overrun clutch OR/
The operating pressure (backup pressure) of C is taken as the line pressure. Also, during running with engine braking in the first gear, the pressure toward the low reverse brake LR/B is reduced to a predetermined value by the pressure reducing action of the range pressure reducing valve 54, so that the capacity of the low reverse brake is adjusted to meet the demand. This can prevent engine brake shock from occurring. FIG. 4 shows a backup pressure control device 20 of the present invention.
0, and the backup pressure control device 200 is
A throttle opening detection means 201, a vehicle speed detection means 202, a range position detection means 203 using an inhibitor switch (not shown), a coasting state detection means 204 using an idle switch or a negative pressure switch, and a range or range Gear position detection means 205 in the D range immediately before selection is provided, and detection signals from these detection means 201, 202, 203, 204, and 205 are input to a microcomputer 206. The microcomputer 206 includes the range position detection means 203.
means 207 for determining the current driving range based on a signal from the coasting state detecting means 2;
means 208 for determining whether the current state is coasting based on a signal from 04; and whether backup pressure is being generated in the hydraulic pressure control device;
In other words, a means 209 for determining whether the overrun clutch OR/C or low reverse brake LR/B engagement pressure is being generated, and a means 210 for calculating the target backup pressure according to the shift state.
and a driving means 211 for duty-controlling the duty solenoid 24. FIG. 5 shows a flowchart for executing a program processed by the microcomputer 206, and this flowchart includes FIGS.
Subroutines shown in B, C, and D are provided. Here, before explaining the flowchart of FIG. 5, the subrate shown in FIG. 6 will be explained first. Here, we assume that A in the figure is the first subroutine, B in the figure is the second subroutine, and C in the figure is the third subroutine.
The subroutine D in the figure is called a fourth subroutine. In the first subroutine, a throttle value is read in step 1100, a basic line pressure value corresponding to the load is calculated in step 1101 based on this throttle value, and then the duty solenoid 24 is controlled in step 1102. Set the duty data. In the second subroutine, in step 1200, the vehicle speed is
Vsp is read, a target backup pressure (line pressure) is set in step 1201 using this vehicle speed Vsp and the backup data shown in FIG. 7, and duty data corresponding to this target backup pressure is set in step 1202. However, the backup data shown in Fig. 7 has two characteristics ( _D4 select backup data type corresponding to 4th gear and
In the second subroutine, the target backup pressure is determined based on _{the D4} select backup data set to relatively high pressure characteristics. . In the third subroutine, in step 1300, the vehicle speed is
Vsp is read, a target backup pressure is set in step 1301 based on the _D3 select backup data set to the relatively low pressure characteristics shown in FIG. Set duty data. In the fourth subroutine, in step 1400, the duty data is simply set to 0, that is, the duty ratio (100%) is set so that the control pressure by the duty solenoid 24 becomes zero. Next, the main routine shown in FIG. 5 will be explained. First, at step 1000, drive range (D,
, range), and if YES, proceed to step 1001 to determine whether it is in the D range. If the step 1001 is NO, that is, if it is a range or range, the step 1001 is NO.
At 1002, it is determined whether the coasting state is present.
If it is in the coasting state (YES), it is determined in step 1003 whether or not backup pressure is being output, and if it is determined in step 1003 that backup pressure is not being output (NO), the process proceeds to step 1004. It is determined whether the gear position before switching to the manual range is D ₄ or not. If it is not D ₄ (NO), it is determined in step 1005 whether the gear position before switching is D ₃ . If it is determined in step 1005 that the gear position before switching is not D ₃ (NO), that is, if the gear position before switching is D ₂ or D ₁ ,
Proceeding to step 1006, in step 1006 the first
The subroutine is processed to obtain duty data based on the throttle value, and based on this duty data, duty is output to the duty solenoid 24 in step 1007. On the other hand, the step
If it is determined in step 1001 that the vehicle is in the D range (YES), or if it is determined in step 1002 that it is not coasting (NO), it is necessary to output backup pressure by proceeding to step 1008 and clearing the backup flag. After confirming that there is no such file, proceed to step 1006 and perform the same process. In these cases, normal line pressure control is performed. Next, if it is determined in step 1004 that the gear position before switching is _D4 (YES), the process proceeds to step 1010, where the _D4 backup flag is set, and the process proceeds to step 1011. In this step 1011, the processing of the second subroutine is performed, and the process shown in FIG.
D _4Set the duty data based on the backup data date and vehicle speed, and then proceed to the step above.
1007 performs duty output. This results in
A backup pressure that conforms to the characteristics shown in FIG. 7A is output. On the other hand, if it is determined in step 1005 that the pre-shift gear position is _D3 (YES), the process proceeds to step 1020, where the _D3 backup flag is set, and the process proceeds to step 1021. In this step 1021, the processing of the third subroutine is performed, and the process shown in FIG.
D ₃ Set the duty data based on the select backup data and vehicle speed, and then proceed to the step above.
1007 performs duty output. As a result, the seventh
Backup pressure is output in accordance with the characteristics shown in (b) of the figure. On the other hand, if it is determined in step 1003 that the backup pressure is being output (YES), the process proceeds to step 1030, where it is determined whether the range is in 1st gear or not. When the backup pressure at the first speed is supplied to the brake LR/B, the backup pressure at the first speed is controlled by the pressure reducing action of the range pressure reducing valve 54, so there is no need to control the line pressure itself. The process advances to step 1008 and the same processing is performed thereafter. Also, in step 1030, the gear is not in 1st gear (NO).
In other words, range, range 2
If it is determined that the speed is fast, proceed to step 1031,
D Determine whether backup pressure control is required when engine braking is applied from _4th gear. If _D4 backup is required (YES) in step 1031, step 1010
Proceed to and perform the same processing below. On the other hand, if it is determined in step 1031 that it is not a D ₄ backup (NO), that is, if it is a D ₃ backup, the process advances to step 1020 and the same processing is performed thereafter. Furthermore, if it is determined in step 1000 that the vehicle is not in the travel range (NO), that is, in the P or N range, the process proceeds to step 1040, where the fourth subroutine is executed, and the process returns to step 1007 with line pressure control skipped. Proceed to perform duty output. By performing the above program processing,
In the backup pressure control device 200 of this embodiment,
When the D range 4th speed (D ₄ ) or 3rd speed (D ₃ ) is downshifted from the manual range to the 2nd speed of the range, the duty ratio of the duty solenoid 24 will be in accordance with the data shown in FIG. The line pressure is controlled to be high via the pressure regulator valve 20. That is, when downshifting to the second manual range speed, as described above, line pressure as backup pressure is supplied to the overrun clutch OR/C via the overrun clutch pressure reducing valve 62, and engine braking is applied. The backup pressure (line pressure) during second gear is changed by the duty ratio control of the duty solenoid ₂₄ as shown in FIG. Controlled in accordance with _D4 Select Backup Data Characteristics A in Figure 7, and
During 2nd speed engine braking due to downshifting from _D3 , control is performed in accordance with the _D3 select backup data characteristics shown in FIG. Therefore, even when the second speed engine brake is applied, when the gear position before range switching is _D3 , the line pressure, that is, the backup pressure, is set lower than when the gear position is _D4 . In other words, if the gear position before switching is D ₄ , the engine speed is low;
Since a large negative torque is generated in the engine when shifting to second gear, high back-up pressure is required to prevent overrun clutch OR/C and band brake B/B from slipping. The _D4 select backup data characteristic A is set to satisfy this requirement, and its slippage is reliably prevented. At the same time, it is set to a value that does not supply unnecessary high pressure, and is also designed to prevent the occurrence of a fastening shock. On the other hand, if the gear position before switching is D ₃ ,
The engine speed is higher than in the case of D ₄ ,
Because the torque generated by engine braking is small, the _D3 select backup data characteristic is set lower than the _D4 select backup data characteristic, and the overrun clutch is
Unnecessary fastening of OR/C and band brake B/B is prevented. In addition, even when controlling the line pressure according to the _D3 select backup data characteristics, the overrun clutch OR/
Needless to say, the settings are made to prevent slipping of C and band brakes B/B. Furthermore, in this embodiment, the D ₄ and D ₃ select backup data characteristics (A and B) are set so that the line pressure increases depending on the vehicle speed Vsp, so that the engine from the same gear position Even when the brakes are applied, the higher the vehicle speed, the higher the back-up pressure and the overrun clutch OR/C.
and band brake B/B to prevent slipping, and the lower the vehicle speed, the lower the backup pressure to reduce the engagement shock of overrun clutch OR/C and band brake B/B. There is. In other words, in the backup control device 200 of this embodiment, the backup pressure is controlled according to the gear position and vehicle speed before shifting to manual range 2nd speed, so when the engine brake is applied at manual range 2nd speed, the overrun clutch is activated. Prevents slipping of the overrun clutch OR/C and band brake B/B, in other words, ensures engine braking while further reducing the engagement shock of the overrun clutch OR/C and band brake B/B, that is, the shift shock during downshifts. . Furthermore, the backup pressure control device 20 of this embodiment
0, the coasting state detection means 20
4 is provided, and based on the detection signal from this means 204, step 1002 in the flowchart of FIG.
As shown in Figure 2, one criterion for determining whether or not to perform a backup is depending on whether or not the coasting state is present. Therefore, if coasting is released by depressing the accelerator, in other words, if drive torque is generated, the step
At 1008, the backup flag is cleared and line pressure control is performed in accordance with normal driving conditions (vehicle speed, throttle opening). Therefore, when the accelerator is turned on and the D range is selected again from the manual range, or when the range is selected from range to range, during an upshift, the high backup pressure is released and normal line pressure is generated, so the upshift is performed. This prevents the occurrence of a fastening shock in the friction element that is sometimes fastened. In addition, in this embodiment, manual range 1
When downshifting to high speed, the range pressure reducing valve 54
Since the backup pressure that is hydraulically controlled is supplied to the low reverse brake LR/B, the backup pressure control by the duty solenoid 24 is not performed when the engine brake is applied in 1st gear of the manual range. Although shown, the low reverse brake LR/B is not limited to this.
It is also possible to connect the line pressure directly with the line pressure, and to control the line pressure with the duty solenoid 24 even when the manual range is in first gear. Effects of the Invention As explained above, in the backup pressure control device for an automatic transmission of the present invention, when the engine brake is applied after switching from the automatic shift range to the manual range, the gear position immediately before switching to the manual range is set to high gear. Since the backup pressure is controlled so that the higher the pressure is, the more appropriate the backup pressure can be applied depending on the magnitude of the torque that the overrun clutch receives during engine braking. In other words, when range switching is performed from the high speed gear where the torque during engine braking is large, the overrun clutch can be reliably engaged without slipping due to the relatively high backup pressure, and the When range switching is performed from a low speed gear where the torque is small, the relatively low backup pressure can significantly reduce the engagement shock of the friction element, that is, the shift shock, and improve the ride comfort of the vehicle. Furthermore, by appropriately controlling the backup pressure, unnecessary pressure generation can be prevented, and as the load of pressure generation is reduced, fuel efficiency and power performance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the concept of a backup pressure control device of the present invention, and FIG. 2 is an overall circuit diagram showing an embodiment of a hydraulic pressure control device for an automatic transmission in which the engine torque detection device of the present invention is used. FIG. 3 is a schematic diagram showing an embodiment of the power transmission train of an automatic transmission to which the hydraulic pressure control device shown in FIG. 2 is applied, and FIG. 4 shows an embodiment of the backup pressure control device of the present invention. FIG. 5 is a flowchart of an embodiment for executing the program of the backup pressure control device of the present invention, and FIGS. 6A, B, C, and D each show a subroutine of the flowchart shown in FIG. 5. Flow chart, Fig. 7 is a characteristic diagram of select backup data showing line pressure with respect to vehicle speed used in the present invention, Fig. 8 is a characteristic diagram of line pressure with respect to the duty ratio of the duty solenoid, and Fig. 9 is a characteristic diagram of the line pressure with respect to the duty ratio of the duty solenoid. FIG. 3 is a hydraulic characteristic diagram of the backup pressure control device. 200...Backup pressure control device, 201...
...Throttle opening detection means, 202...Vehicle speed detection means, 203...Range position detection means, 204...
... coasting state detection means, 205 ... pre-shift gear position detection means, 206 ... microcomputer, 207 ... travel range judgment means,
208...Coasting state determination means, 209
... Backup pressure judgment means, 210 ... Backup pressure calculation means, 211 ... Drive means, OR/
C...Overrun clutch (friction element).

Claims (1)

[Scope of Claims] 1. An overrun clutch for applying engine braking is provided in parallel with a one-way clutch, and when switching from an automatic shift range to a manual range, a back-up is applied to the overrun clutch by increasing line pressure. In an automatic transmission configured to supply pressure to tighten the overrun clutch, the line pressure has an actuator operated by a control signal, and the line pressure that becomes backup pressure is variably controlled based on the control signal. a control means; a range change detection means for detecting a switching operation from the automatic transmission range to the manual range; a gear position detection means for detecting a gear position in the automatic transmission range immediately before switching to the manual range; A backup pressure setting means for setting a target backup pressure such that the pressure becomes higher as the stage increases; and a drive control means for outputting a control signal to the line pressure control means in accordance with the target backup pressure. Features a backup pressure control device for automatic transmissions.