JPH0481057B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a device that performs downshift timing control and engine brake control of an automatic transmission. (Prior Art) An automatic transmission is configured to automatically change gears by switching a power transmission path by selectively operating various friction elements (clutches, brakes, one-way clutches, etc.). By the way, when downshifting, a sudden change in engine speed occurs due to a change in gear ratio before and after the downshift, and this sudden change in engine speed is mainly due to the shift increasing the engine load (accelerator pedal depression amount). Coupled with the fact that this is done during power-on driving, a large shift shock occurs. The automatic transmission also includes a one-way clutch as a reaction force element for the rotating member, and its operation allows the reaction force from the rotating member to be received to enable the above-mentioned power transmission. Therefore, when reverse drive torque is applied to the rotating member, it can be blocked by releasing the one-way clutch and the occurrence of shock or rattling noise can be prevented, but the one-way clutch does not provide engine braking. To solve the former problem, it is common practice to set a so-called neutral interval by controlling the timing to delay the downshift until the engine speed reaches the post-shift engine speed determined from the post-shift gear ratio and vehicle speed. To solve the latter problem, it is common practice to provide an engine braking friction element in parallel with the one-way clutch, and operate this element as required to apply engine braking. By the way, conventionally, the timing control of downshift and the operation control of the friction element for engine braking have been performed using THM-
As seen in the 3-2 downshift control and overrun clutch operation control of the 700 type transmission, or the 3-2 downshift control of the RN4F02A type (RL4F02A type) and RN3F01A type automatic transaxle manufactured by Nissan Motor Co., Ltd. and low reverse brake operation control,
Usually, the former control was performed by a governor pressure corresponding to the vehicle speed, and the latter control was performed by switching a manual valve. (Problem to be Solved by the Invention) However, in such a conventional configuration, when attempting to electronically control an automatic transmission, the electronic control would eliminate the need for governor pressure, and a governor valve to generate this would be required. Although it can be omitted, governor pressure must still be generated for timing control of the downshift. Furthermore, since engine brake control is performed by switching manual valves, there is little flexibility in adapting to electronic control. Furthermore, in electronically controlling both of these controls, a solenoid that responds to vehicle speed information creates governor pressure and uses this to control the timing of downshifts, and a solenoid that responds to manual valve switching generates engine brake commands. Pressure is created and used for engine braking control, but such control requiring separate solenoids is disadvantageous in terms of space and cost. (Means for Solving the Problems) The present invention provides (a) the engine brake friction element is disposed in parallel to the one-way clutch as described above, and during power-on driving, the engine brake friction element is operated; The deactivation does not affect the power transmission state and can be kept in the deactivated state, and (b) the timing control of downshifting is necessary for the above purpose mainly during downshifting when the engine load is increased. Therefore, (c) Of the above two controls, engine brake control is required during coasting, and downshift timing control is required during power-on driving.In other words, these two controls have different request timings, but are common. a downshift timing valve that controls timing to delay the downshift until the engine speed reaches a post-shift engine speed determined by the post-shift gear ratio and the vehicle speed, based on the fact that the downshift can be performed by the solenoid valve; An automatic transmission comprising an engine brake control valve that operates an engine brake friction element to obtain engine brake,
A shuttle that increases in proportion to the engine load and responds to the line pressure that is increased in a certain gear engine brake range, becoming the first position when the line pressure is below a certain line pressure and the second position when the line pressure is above the certain line pressure. a valve is provided, in a first position the engine brake control valve is controllable by the electromagnetic valve and the downshift timing valve is maintained in a state in which the timing control is disabled; in a second position the downshift timing valve is controlled by the solenoid valve; The shuttle valve is configured to be controllable by a solenoid valve and to maintain the engine brake control valve in a state in which the engine brake friction element is inactivated, and the shuttle valve is configured to be able to be controlled by a solenoid valve and to maintain the engine brake control valve in a state in which the engine brake friction element is inactivated. is configured to be locked at the first position. (Operation) The shuttle valve is in the first position below a certain line pressure, i.e. below a corresponding engine load;
In this position, the engine brake control valve is controlled by a solenoid valve, and the engine brake friction element can be actuated as appropriate to obtain engine brake. In this first position, the downshift timing valve is kept in a state where the downshift is not controlled by timing, but during the low engine load,
In other words, there is no problem because downshift timing control is not required during coasting. Above a certain line pressure, that is, above the corresponding engine load, the shuttle valve is in the second position, and in this second position, the downshift timing valve is controlled by the same solenoid valve as above, and the downshift is controlled by the engine rotation. The shift shock can be alleviated by controlling the timing to delay the number of engine revolutions after the shift determined by the gear ratio after the shift and the vehicle speed. In this second position, the engine brake control valve is kept in a state in which the engine brake friction element is not activated, but the engine brake friction element does not participate in power transmission during power-on driving where the engine load is higher than the engine load. Therefore, there is no problem. Therefore, it is possible to perform both engine brake control and downshift timing control using a common solenoid valve, which is advantageous in terms of space and cost.In addition, these controls can be freely electronically controlled, and the governor valve can be controlled from these controls. can be omitted. In addition, in the engine brake range of a certain gear stage, the shuttle valve is locked at the first position. Therefore, even if the line pressure is increased in the relevant range, the shuttle valve that responds to this can be prevented from erroneously operating to the second position even though the engine brake is requested, and this causes the engine brake friction element to operate. It is possible to avoid the inconvenience that engine braking becomes impossible due to engine braking being disabled. (Example) Hereinafter, the present invention will be described in detail based on the illustrated example. The drawing shows one embodiment of the control device of the present invention, and an automatic transmission to which this device is applied has a forward clutch F/
C, band brake B/B, high clutch H/C
and an overrun clutch (friction element for engine braking) OR/C, the first speed is selected by the operation of the forward clutch F/C, and the second speed is selected by the operation of this and the band brake B/B. , Forward clutch F/C operation and high clutch H/C
3rd speed is selected by the operation of . In addition,
Activation and deactivation of the band brake B/B is executed by the band servo B/S, and when supplying pressure to the servo apply chamber S/A, the servo B/S activates the brake B/B, and the servo relay chamber S/A is supplied with pressure. S/R
When supplying pressure to the servo apply chamber S/A, the servo B/S deactivates the brake B/B depending on the magnitude of the piston pressure receiving area, regardless of the presence or absence of pressure in the servo apply chamber S/A. Then, the first speed, the second speed
overrun clutch when 3rd gear is selected
It is assumed that by operating OR/C, the automatic transmission can obtain engine braking at the corresponding gear. The automatic transmission is further provided with a manual valve 1, a pilot valve 2, a 1-2 speed change valve 3, and a 2-3 speed change valve 4, as well as a solenoid 9 as a solenoid valve that constitutes the main part of the control device of the present invention, and a shuttle. Valves 5, 3-2 are provided with a timing valve (downshift timing valve) 6 and an overrun clutch control valve (engine brake control valve) 7. Manual valve 1 sets spool 1a to P range when the driver wishes to park, sets spool 1a to R range when the driver wishes to reverse, sets spool 1a to N range when the driver wishes to stop, and sets spool 1a to N range when the driver wishes to automatically shift forward. Spool 1a is set to D range, and when 2nd gear engine braking is desired, spool 1a is set to range.
Also, when first speed engine braking is desired, the spool 1a is set to a range, and in each range, the output ports 1R, 1D, 1, 1 output the line pressure P _L from the line pressure circuit L as shown in the following table. shall be

[Table] In this table, ○ marks indicate ports that output line pressure, and unmarked ports indicate ports that are opened to the atmosphere. In addition, the line pressure P _L is determined by the automatic transaxle type RN4F02A, RL4F02A published by Nissan Motor Co., Ltd.
As described in "Model Maintenance Manual" (A261C06), the throttle opening changes depending on the throttle opening and vehicle speed, and it is relatively low during coasting and relatively high during power-on driving.
When engine braking is required while maintaining speed, the band brake B/B, which continues to operate as described below, functions in the trailing direction with the input of reverse drive torque, so it is necessary to increase the line pressure P _L , which is the operating oil pressure. Because of this, line pressure is
The pressure of P _L shall be particularly increased compared to normal. The pilot valve 2 includes a spool 2b elastically supported at the upper half position in the figure by a spring 2a, and at this spool position, the line pressure P _L from the circuit L is outputted to the pilot pressure circuit 8 in order to increase the pilot pressure thereto. The pilot pressure is fed back to the chamber 2c, and as the pilot pressure increases, the spool 2b is moved to the right in the figure. Pilot pressure is spring 2
When the spring force exceeds the value corresponding to the spring force a, the spool 2b cuts off the circuit 8 from the circuit L and reduces the pilot pressure through the drain port 2d, which causes the spool 2b to return to the lower half position in the figure. By the way, the reduction in pilot pressure is stopped. Thus, the pilot valve 2 transfers the pilot pressure of the circuit 8 to the spring 2a.
Maintain a constant value corresponding to the spring force. The 1-2 speed change valve 3 and the 2-3 speed change valve 4 are configured by elastically supporting spools 3a and 4a at downshift positions shown in the right half and left half by springs 3b and 4b, respectively. and ports 3c, 4c
is connected to the drain ports 3d and 4d, and the chambers 3e and 4e are connected to the drain ports 3d and 4d.
When the spools 3a, 4a are brought to the upshift positions shown in the left half and right half by the shift pressure P _S , the ports 3c, 4c are communicated with the ports 3f, 4f. The shuttle valve 5 is constructed by elastically supporting a spool 5a at the left half position in the figure by a spring 5b. Then, at this spool position, connect port 5c to drain port 5d.
and port 5e to port 5f;
When the spool 5a is moved to the right half position in the figure against the spring 5b due to the pressure inside the chamber 5g, the port 5c is connected to the port 5f, and the port 5e is connected to the port 5h. 3-2 Timing valve 6 connects spool 6a to spring 6
The spool 6a is elastically supported at the left half position in the figure by b.
The structure is such that it is moved to the right half position in the figure as appropriate by the pressure applied to the chamber 6c. This valve 6 opens circuits 10 and 11 at the left half position of the spool 6a in the figure, and opens the circuits 10 and 11 at the right half position of the spool 6a in the figure.
11 shall be cut off. The overrun clutch control valve 7 is configured such that the spool 7a is resiliently supported in the left half position in the figure by a spring 7b, and the spool 7a is appropriately switched to the right half position in the figure by pressure applied to the chamber 7c. The valve 7 communicates the port 7d with the port 7e at the left half of the spool 7a in the figure, and communicates the port 7d with the drain port 7f at the right half of the spool 7a in the figure. The pilot pressure circuit 8 is connected to the shuttle valve port 5f,
5h, and an orifice 12 is inserted in the middle of the pilot pressure circuit 8 which is connected to the port 5f. A drain port 13 is provided downstream of the orifice 12, and a solenoid 9 is provided opposite to this.
The solenoid 9 is composed of a coil 9a, a plunger 9b, and a spring 9c, and when the coil 9a is OFF (de-energized)
When the plunger 9b closes the drain port 13 by the spring force of the spring 9c and makes the pressure to the port 5f the same value as the pilot pressure, the coil 9a is turned ON.
(When energized), the plunger 9b resists the spring force of the spring 9c and descends in the figure to open the drain port 13 and the pressure to the port 5f is removed from the drain port 13, thereby reducing the pressure to zero. Port 5c of shuttle valve 5 is connected to chamber 6c by circuit 14, and port 5e is connected to chamber 7 by circuit 15.
Connect to c. Port 1D of manual valve 1 is connected to forward clutch F/C by circuit 16, and among circuits 17 to 20 branching from circuit 16, circuit 17 is connected to port 7e, circuit 18 is connected to chamber 5g,
Circuit 19 is connected to port 3f, circuit 20 is connected to port 4f
Connect to each. The port 3c of the 1-2 speed change valve 3 is connected to the servo apply chamber S/A by a circuit 21, the circuit 10 is connected to the port 4c of the 2-3 speed change valve 4, and the circuit 10 is connected to the servo release chamber S/R. 11 respectively. A one-way orifice 22 is separately connected between the circuits 10 and 11, and is constituted by a check valve 22a and an orifice 22b arranged in parallel, which function for oil flow from the circuit 11 to the circuit 10. A circuit 23 branching off from the circuit 10 is provided, and this circuit 23 is connected to the high clutch H/C. In addition, overrun clutch control valve 7
The remaining port 7d of is connected by circuit 24 to the overrun clutch OR/C. Further, a chamber 5i containing a spring 5b of the shuttle valve 5 is connected to the manual valve port 1 through a circuit 25. The operation of the above embodiment will be explained next. While the driver desires forward automatic gear shifting and sets the spool 1a of the manual valve 1 to the D range position as shown, line pressure P _L from circuit L is output to circuit 16, and this line pressure is applied to forward clutch F. /
In addition to being supplied to C to keep it operating, circuit 17
20 to reach the connection point of these circuits. Here, the shift pressure P _S is low, and the 1-2 shift valves 3 and 2
-3 When the spools 3a and 4a of the speed change valve 4 are both in the downshift position, the servo apply chamber S/A communicates with the drain port 3d via the circuit 21 and the port 3c, and the band brake B/B is deactivated and the high clutch is activated. The H/C also communicates with the drain port 4d via the circuits 23, 10 and the port 4c, and is kept inactive. In this case, the automatic transmission selects the first speed by operating the forward clutch F/C. From this state, when the spool 3a of the 1-2 speed change valve 3 is switched to the upshift position shown in the left half due to an increase in the speed change pressure P _S , the line pressure from the circuit 19 passes through the circuit 21 to the servo apply chamber S/A. reached and activates band brake B/B. At this time, the automatic transmission selects the second speed by operating the forward clutch F/C and the band brake B/B. As the shift pressure P _S further increases, the spool 4a of the 2-3 shift valve 4 is also switched to the upshift position shown in the right half, and the line pressure from the circuit 20 shifts to the circuit 1.
0 and 23, reaching the high clutch H/C and activating it, line pressure from the circuit 20 passes through the circuit 10, check valve 22a, and circuit 11, reaches the servo release chamber S/R, and activates the band brake B/B. deactivate. At this time, the automatic transmission selects the third speed by operating the forward clutch F/C and the high clutch H/C. Thereafter, when the spool 4a of the 2-3 speed change valve 4 is switched to the downshift position shown in the left half due to a decrease in the speed change pressure P _S , the port 4c communicates with the drain port 4d, and the pressure being supplied to the high clutch H/C is The band brake B/B is activated by removing the pressure supplied to the servo release chamber S/R while controlling the speed as described later, and the automatic transmission is activated as appropriate. It is possible to downshift from third speed to second speed under downshift timing control. Line pressure from circuit 18 is applied to chamber 5 of shuttle valve 5.
g, and the stroke of the spool 5a is controlled.
By the way, in the D range, the manual valve 1 uses the port 1 as the drain port, as is clear from Table 1 above, and the chamber 5i connected to this via the circuit 25 is kept in an unpressurized state, and the spool 5a is operated as follows. Stroke controlled. That is, as mentioned above, the line pressure to the chamber 5g is relatively low during coasting, and cannot overcome the spring force of the spring 5b, and the spool 5a is placed in the left half position in the figure. Move the spool 5a to the right half position in the figure against the spring force. First, to explain the operation when the shuttle valve 5 is in the left half state in the figure during coasting, at this time the port 5
With the communication between e and 5f, the overrun clutch control valve 7 is in a state where its stroke can be controlled by the solenoid 9. In other words, there is an engine brake command from the driver via a switch or the like, or an automatic engine brake command based on the determination result of the road surface slope, etc., and this causes the solenoid coil 9a to
When is turned ON, the plunger 9b opens the donlen port 13, thereby reducing the pressure to the port 5f, and thus the pressure in the chamber 7c, to zero, thereby placing the overrun clutch control valve 7 in the left half state in the figure. This causes line pressure from circuit 17 to pass through circuit 24 to overrun clutch OR/C, activating it. In this case, the automatic transmission selects the selected gear,
In other words, engine braking in first, second, or third gear can be achieved during automatic gear shifting. By the way, during coasting, the chamber 6c of the 3-2 timing valve 6 communicates with the drain port 5d due to the state of the shuttle valve 5 in the left half position in the figure, and the spool 6a of the valve is placed in the left half position in the figure. There is. In this case, the pressure in the servo release chamber S/R is removed through the orifice 2.
2b, mostly circuits 11 and 10
The downshift from the third speed to the second speed is completed immediately without timing control. However, there is no problem because downshift timing control is not required during the coasting as described above. Next, when the shuttle valve 5 is in the right half state in the figure during power-on running, the 3-2 timing valve 6 is in a state where the stroke can be controlled by the solenoid 9 due to communication between the ports 5c and 5f. By the way, at this time, the solenoid coil 9a is activated at a predetermined vehicle speed or higher.
The valve is turned OFF, thereby supplying the same pressure as the pilot pressure to the chamber 6c via the ports 5f, 5c and the circuit 14, and setting the 3-2 timing valve 6 to the right half state in the figure. Thus 3-2 timing valve 6
The circuits 10 and 11 are cut off, and the pressure in the servo release chamber S/R is removed while the speed is controlled by the orifice 22b.
A downshift from speed to second speed can be performed under downshift timing control.
Therefore, the shift can be completed when the engine speed increases to a post-shift engine speed commensurate with the vehicle speed and the gear ratio after the shift, and the shift shock can be reduced. Note that the solenoid coil 9a is not kept OFF, but is turned ON when the engine speed reaches the above value, and at this point, the 3-2 timing valve 6 is set to the downshift timing control discontinued state shown in the left half. It goes without saying that the above purpose can be achieved even more completely by doing so. By the way, during the power-on running, the pilot pressure from the circuit 8 reaches the chamber 7c via the circuit 15 due to the state of the right half of the shuttle valve 5 in the figure, causing the overrun clutch control valve 7 to move to the right half in the figure. Keep it in good condition. In this case, the circuit 24 connects to the drain port 7f and holds the overrun clutch OR/C inactive, keeping the engine brake in a state where it cannot be obtained, but engine braking is not required during the power-on driving, and as described above As the overrun clutch OR/C (frictional element for engine braking) operates or deactivates, it does not affect power transmission, so there is no problem. In addition, if the driver particularly wants to maintain engine braking in 2nd gear, the driver should use the manual valve spool 1a.
Microwave. In this range, the line pressure P _L is increased more than usual due to the above-mentioned reason, and this causes the spool 5a to be switched to the right half position in the figure even though it is coasting in the chamber 5g, and there is a risk that the engine brake will not work. , this can be prevented as follows. That is, in this range, as shown in Table 1 above, manual valve 1 also outputs line pressure P _L from circuit L to port 1, and this line pressure reaches chamber 5i via circuit 25. Therefore, the spool 5a is locked in the left half position in the drawing together with the spring force of the spring 5b, and the overrun clutch control valve 7 is locked.
is maintained in a controllable state by solenoid 9. However, in this range, the coil 9a of the solenoid 9 is kept OFF, thereby keeping the overrun clutch OR/C in the operating state, so that engine braking can be obtained. On the other hand, the line pressure from port 1 reaches a predetermined location via a circuit network not shown, and the operation of the forward clutch F/C and band brake B/B fixes the 2nd gear, and then shifts to the 3rd gear. Engine braking in second gear can be obtained without upshifting. Note that during engine braking, this band brake functions in the trailing direction due to the reverse drive torque from the wheel side, causing a reduction in capacity, but this is compensated for by increasing the line pressure P _L.
It is possible to prevent the engine brake from becoming less effective due to slipping of the band brake B/B. Also, during this time, the left half of the shuttle valve 5 in the figure is locked, and as described above, the 3-2 timing valve 6 is locked.
is maintained in a state in which the downshift timing control shown in the left half is not performed, but the 3rd gear is not selected in the range, and therefore the 3→2 downshift is not performed, so there is no problem. do not have. Next, if the driver wants to maintain the engine braking state in 1st gear, the driver must use the manual valve spool 1a.
Microwave. In this Reny, line pressure from circuit L is also output to port 1 as shown in Table 1 above. The line pressure from port 1 passes through a circuit network (not shown) to a predetermined location to lock the first gear in place by prohibiting the operation of friction elements other than the forward clutch F/C. (At vehicle speeds that cause And overrun clutch OR/C
By continuing to operate in the same manner as in the above range, an engine braking state is obtained. When the driver desires to drive in reverse and sets the manual valve spool 1a to the R range, the line pressure from circuit L is output only to port 1R as shown in Table 1 above. This line pressure reaches a friction element (not shown) for reverse selection and activates it, allowing the vehicle to travel in reverse. (Effects of the Invention) As described above, the control device of the present invention has a configuration in which downshift (in the illustrated example, 3→2 downshift) timing control and engine brake control are performed by one common solenoid valve (solenoid 9). Therefore, in addition to being advantageous in terms of space and cost,
These controls can be freely electronically controlled, and a governor valve can be omitted from these controls. In addition, the shuttle valve is configured to be locked in a position where the engine brake control valve can be controlled by the electromagnetic valve (solenoid 9) in a certain gear engine brake range (range in the illustrated example) in which the line pressure is to be increased. Therefore, even if the line pressure is increased in the range, it is possible to avoid the inconvenience that the shuttle valve 5 that responds to the increase malfunctions and becomes unable to provide engine braking.

[Brief explanation of drawings]

The drawing is a hydraulic circuit diagram showing an embodiment of the control device of the present invention. 1...Manual valve, 2...Pilot valve, 3
...1-2 speed change valve, 4...2-3 speed change valve, 5...
Shuttle valve, 6...3-2 timing valve (downshift timing valve), 7...Overrun clutch control valve (engine brake control valve), L...Line circuit, 9...Solenoid (electromagnetic valve), 12... ...Orifice, 13...Drain port, 22...One-way orifice, F/C
...Forward clutch, B/B...Band brake, B/S...Band servo, H/C...High clutch, OR/C...Overrun clutch (friction element for engine brake).

Claims (1)

[Claims] 1. A downshift timing valve that controls timing to delay downshift until the engine speed reaches the post-shift engine speed determined by the post-shift gear ratio and vehicle speed, and operates an engine brake friction element. In an automatic transmission equipped with an engine brake control valve, the line pressure increases in proportion to the engine load and increases in a certain gear engine brake range, A shuttle valve is provided which is in a first position when the line pressure is less than a certain line pressure and is in a second position when the line pressure is above the certain line pressure, and the engine brake control valve is controllable by a solenoid valve in the first position of the shuttle valve, and the down control valve is controlled by a solenoid valve. The shift timing valve is held in a state where the timing control is disabled, the downshift timing valve is made controllable by the electromagnetic valve in the second position, and the engine brake control valve is held in a state where the engine brake friction element is inoperable. The downshift timing of an automatic transmission, characterized in that the shuttle valve is configured to maintain a state in which the downshift is performed, and the shuttle valve is configured to be locked at the first position in the certain gear engine brake range. Control and engine brake control device.