JPS6252183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a lock-up automatic transmission, and more particularly to an improvement in a lock-up control device for preventing gear shift shock.

(Prior Art) Automatic transmissions generally include a torque converter in the engine power transmission system for the purpose of increasing torque from the engine. A normal torque converter uses an input element (pump impeller) driven by the engine to circulate hydraulic oil within the torque converter, and this hydraulic oil rotates the output element (turbine runner) while increasing the torque under the reaction force of the stator. (converter state). Therefore, the torque converter cannot avoid slipping between the pump impeller and the turbine runner during operation, and automatic transmissions equipped with the torque converter in the power transmission system are
Although it is easy to operate, it has the disadvantage of poor fuel efficiency due to poor power transmission efficiency. For this reason, conventionally, in relatively high vehicle speed ranges where engine torque fluctuations are not a problem, the turbine runner is directly connected to the pump impeller (lock-up state), thereby eliminating slip between the two. A lock-up automatic transmission equipped with this type of torque converter in the power transmission system has been put into practical use in some vehicles.

By the way, the lock-up region of the automatic transmission in which the torque converter with the direct coupling clutch is brought into the lock-up state when the vehicle speed exceeds a set vehicle speed (lock-up vehicle speed) for each shift position is as shown in FIG. 9, for example.
This figure shows the upshift shift pattern of a three-speed forward automatic transmission, in which V ₁ , V ₂ , and V ₃ are the first
A, at the lock-up vehicle speed in 2nd and 3rd gears.
B and C are lock-up areas at first, second and third speeds. In the case of an automatic transmission that performs lock-up at or above the lock-up vehicle speed at each shift position, when driving through an automatic shift with the accelerator pedal pressed down relatively heavily (with the throttle opening still large), the lock-up ranges A to C are Since they are in contact with each other in sequence, the torque converter is kept in a locked-up state during gear shifting. However, if a shift is performed with the torque converter in the locked-up state as described above, the torque converter will not be able to absorb torque fluctuations, resulting in a large shift shock.

Therefore, in this type of lock-up automatic transmission, even in the above-mentioned lock-up region, the lock-up is released and the torque converter is kept in the converter state during gear shifting.
For this purpose, a speed change detection circuit is provided which emits a speed change signal indicating that the speed is being changed for a predetermined period of time after a speed change command.
It has been common practice to temporarily suspend the lock-up state even in the lock-up region while the speed change signal is issued from this circuit.

However, conventionally, when the shift detection circuit shifts from the second speed to the third speed, it outputs a shift signal at the same time as the shift command time _t1 as shown in FIG. Since the lockup is released for a predetermined time T', the lockup is released too quickly, causing the following inconveniences. In other words, automatic transmissions receive a shift command and actually start shifting, that is, before they start operating the friction elements, due to a delay in the response of the hydraulic system.
Time lag is unavoidable. Therefore, if the lock-up is released at the same time as the shift command as in the past, the lock-up will be released before the gear change, and the engine rotation will start at the moment _t1 to _t2 as shown in Fig. 8a. The engine speed rises rapidly, causing what is called engine racing. Furthermore, between the instants _t3 and _t4 when the gear shift is actually being performed, the release of the lock-up has already been interrupted and the lock-up state has returned, and the torque converter cannot absorb the shift shock, causing the engine to As the engine speed increased due to engine speed, a large peak torque was generated at instant _t5 immediately after the gear shift, and a large gear shift shock was unavoidable. This tendency is particularly noticeable when the automatic transmission shifts up from 2nd gear to 3rd gear, especially when the power is on. Since the so-called overlap time for engaging the front clutch, which selects third gear while releasing the second brake, is relatively long, the gear shifting operation will be delayed even more than other gear shifting operations, which will solve the problem mentioned above. was becoming important.

To resolve this issue, lockup interruption time is
It is conceivable to lengthen T' so that it extends to the end of the shift operation, but this still does not solve the problem of engine racing and the accompanying shift shock.

Therefore, the applicant proposed that the above-mentioned speed change detection circuit
As shown in Figure b, a delay circuit is provided to issue a shift signal with a predetermined time delay _T1 after the shift command instant _t1 , and this actually interrupts (OFF) the lockup (L/u) that should be performed when shifting in the lockup region. Japanese Patent Laid-Open No. 1983-1987 describes a lock-up automatic transmission that starts the shift operation in synchronization with the instant _t3 at which the shift operation starts.
This was previously proposed in Publication No. 127856.

However, the delay time t ₁ to _{t 3} from the shift command to the start of the actual shift operation varies depending on product variations, that is, individual differences in the resistance of the shift control oil passage, changes in the viscosity of the hydraulic oil, etc. It was confirmed that the set time _T1 by the delay circuit does not necessarily match the delay times _t1 to _t3 , and that the above-mentioned racing and shift shock cannot be completely prevented.

In order to solve this problem, the applicant first filed a patent application in 1983.
- According to No. 185116, the engine speed changes depending on the type of shift at the actual start of the shift, but for example, as shown in Figure 8 a and b, a peculiar sudden change occurs, and the start of the shift is determined based on the change trend of the engine speed. From the viewpoint of being able to determine the change rate, the rate of change in the engine speed is determined, and when this rate exceeds the set value, it is determined that the shift has started and the lock-up is temporarily interrupted, thereby achieving the desired shift shock reduction effect as described above with reference to Figure 8b. We have already proposed a lock-up automatic transmission that achieves this.

However, as shown by the solid line in FIG. 10, the engine speed does not actually change smoothly, but changes while repeating minute fluctuations that are not particularly related to gear shifting. Therefore, in order to obtain the rate of change of the engine speed as described above, it is necessary to remove the minute fluctuation component, and when the read values of each engine speed are averaged and the smoothed value is detected, this is shown in Fig. 10. is as shown by the dotted line, and is affected by the read value of the engine speed after the peak value _Np but before the peak value _Np , and there is a time delay with respect to the actual engine speed shown by the solid line. Therefore, when determining the start of a shift as described above, if the engine speed decreases by △Ns from the peak value N _p as the start of a shift, then the determination of the start of a shift is △td in Fig. 10. In the above-mentioned lock-up type automatic transmission, the start of the lock-up interruption that should be performed at the time of gear shifting does not coincide with the start time of the variable operation, and is delayed by △td, and the lock-up interruption is not yet performed when the gear shift starts. It was confirmed that it was not possible to reliably reduce the shift shock.

(Object of the Invention) The present invention determines the start of a gear shift operation based on the change trend of the engine speed, but does not make the determination based on a smooth value, but rather detects the change in engine speed that should occur due to the start of the gear shift in real time. It is an object of the present invention to solve the above-mentioned problem caused by the time lag by determining the time when the shift operation starts.

(Structure of the Invention) For this purpose, the present invention, as shown in FIG. The power of
A lock-up type automatic transmission is provided with a lock-up interrupt control means f that brings the lock-up torque converter into a converter state in which the direct-coupled clutch c is temporarily released even in a lock-up region where the direct-coupled clutch c is to be engaged during gear shifting. A shift command detection means g that detects a shift command, and an engine rotation speed detection means h that detects the rotation speed of the engine e.
, an engine speed change trend calculation means i for calculating a change trend in engine speed from the engine speed difference at set time intervals after a shift command; and an engine speed change trend j that should be caused by the actual shift start. a gear shift start determining means l that determines that the shift has started when the number h matches a set number of times or more; an engine rotation speed reference value setting means m that sets the engine rotation speed immediately before the shift start as a reference value; The present invention is characterized in that it further comprises a direct coupling clutch release timing determining means o which instructs the lockup interruption control means f to temporarily release the direct coupling clutch c when the difference between the two and

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

Fig. 2 schematically shows the internal power transmission part of a lock-up automatic transmission with three forward speeds and one reverse speed. Lock-up torque converter 1, input shaft 7, front clutch 104, rear clutch 105, second clutch
Brake 106, low reverse brake 10
7. One-way brake 108, intermediate shaft 10
9, first planetary gear group 110, second planetary gear group 11
1, an output shaft 112, a first governor valve 113, a second governor valve 114, and an oil pump 13. Torque converter 1
consists of a pump impeller 3, a turbine impeller 8, and a stator impeller 9, and the pump impeller 3 is connected to a crankshaft 4.
The torque converter is driven by a rotor, rotates the torque converter hydraulic oil contained therein, and applies torque to a turbine wheel 8 fixed to an input shaft 7. The torque is further transmitted by the input shaft 7 to the transmission gear train. The stator wheel 9 is placed on the sleeve 12 via a one-way clutch 10. The one-way clutch 10 has a structure that allows the stator wheel 9 to rotate in the same direction as the crankshaft 4, that is, in the direction of the arrow (hereinafter referred to as normal rotation), but does not allow rotation in the opposite direction (hereinafter referred to as reverse rotation). ing. The first planetary gear group 110 is the intermediate shaft 1
09, a sun gear 119 fixed to a hollow conductive shaft 118, and a planet consisting of two or more small gears that can rotate and revolve simultaneously while meshing with each of the internal gear 117 and the sun gear 119. The second planetary gear group 111 is composed of a gear 120 and a planetary gear support 121 fixed to the output shaft 112 and supporting the planetary gear 120.
A planetary gear 124 consisting of two or more small gears that can rotate and revolve simultaneously while meshing with each of the sun gear 123, internal gear 122, and sun gear 123, which are fixed to the sun gear 123, and the planetary gear support 125 that supports the planetary gear 124. It consists of front·
The clutch 104 connects the input shaft 7 driven by the turbine wheel 8 and both sun gears 119,1.
Hollow conduction shaft 1 that rotates together with 23
18 through a drum 126, and the rear clutch 105 functions to connect the input shaft 7 and the internal gear 117 of the first planetary gear group 110 through an intermediate shaft 109. second·
The brake 106 fixes both sun gears 119 and 123 by winding and tightening a drum 126 fixed to a hollow conductive shaft 118, and
The reverse brake 107 is the second planetary gear group 11
It serves to fix the planetary gear support 125 of No. 1. The one-way brake 108 is the planetary gear support 12
5 has a structure that allows forward rotation but does not allow reverse rotation. A first governor valve 113 and a second governor valve 114 are fixed to the output shaft 112 and generate governor pressure according to vehicle speed.

Next, a description will be given of the power transmission train when the speed selection rod is set to the D (forward automatic shifting) position.

In this case, only the rear clutch 105, which is the forward input clutch, is initially engaged. Power from the engine via the torque converter 1 is transmitted from the input shaft 7 to the internal gear 117 of the first planetary gear group 110 through the rear clutch 105. The internal gear 117 rotates the planetary gear 120 in the normal direction. Therefore, the sun gear 119 rotates in reverse, and the planet gears 124 of the second planet gear group 111 rotate in the normal direction to reverse the sun gear 123 of the second planet gear group 111, which rotates integrally with the sun gear 119. One-way brake 108 prevents sun gear 123 from reversing planetary gear support 125 and acts as a forward reaction brake. Therefore, the internal gear 122 of the second planetary gear group 111 rotates normally. Therefore, the output shaft 112, which rotates integrally with the internal gear 122, also rotates in the normal direction, and the reduction ratio of the first forward speed is obtained. In this state, the vehicle speed increases and the second
When the brake 106 is engaged, the input shaft 7 is moved to the rear clutch 1 as in the first gear.
05 is transmitted to the internal gear 117. The second brake 106 fixes the drum 126, prevents rotation of the sun gear 119, and acts as a forward reaction brake. For this reason, the planetary gear 120 revolves around the stationary sun gear 119 while rotating, and therefore the planetary gear support 121 and the output shaft 112 integrated therewith
Although it is decelerated, it rotates normally at a faster speed than in the case of the first speed, and the reduction ratio of the second forward speed is obtained.
When the vehicle speed increases further and the second brake 106 is released and the front clutch 104 is engaged, the power transmitted to the input shaft 7 is
One side passes through the rear clutch 105 to the internal gear 11.
7 and the other is transmitted to the sun gear 119 via the front clutch 104. Therefore, the internal gear 117 and the sun gear 119 are interlocked, and together with the planetary gear support 121 and the output shaft 112, they all rotate normally at the same rotational speed to obtain the third forward speed. In this case, the input clutches are the front clutch 104 and the rear clutch 105, and since torque is not increased by the planetary gear, there is no reaction brake.

Next, the power transmission train when the speed selection rod is set to the R (reverse travel) position will be explained.

In this case, the float clutch 104 and the low
Reverse brake 107 is engaged. The power from the engine passes through the torque converter 1 and is transferred from the input shaft 7 to the front clutch 104.
Sun gears 119, 123 through drum 126
guided by. At this time, since the rear planet carrier 125 is fixed by the low reverse brake 107, the sun gears 119, 12
3, the internal gear 122 is decelerated and reversed by the forward rotation described above, and a backward reduction ratio is obtained from the output shaft 112 that rotates integrally with this internal gear.

Figure 3 shows the hydraulic system of the speed change control device related to the above automatic transmission, and shows the oil pump 1.
3. Line pressure adjustment valve 128, pressure increase valve 129, torque converter 1, speed selection valve 130, first governor valve 113, second governor valve 114, 1-2 shift valve 131, 2-3 shift valve 132, throttle pressure reduction valve 133, cut-down valve 134, second lock valve 135, 2-3 timing valve 13
6, solenoid down shift valve 137, throttle back up valve 138, vacuum
Throttle valve 139, vacuum diaphragm 140, front clutch 104, rear clutch 105, second brake 106, servo 1
41, a low reverse brake 107 and a hydraulic circuit network. The oil pump 13 is driven by the prime mover through the drive shaft 4 and the pump impeller 3 of the torque converter 1, and when the engine is running, the oil pump 13 always handles oil from a reservoir 142 through a strainer 143, from which harmful contaminants have been removed, to the line pressure circuit. 144.

The oil is regulated to a predetermined pressure by a line pressure regulating valve 128 and sent to the torque converter 1 and speed selection valve 130 as working oil pressure. The line pressure regulating valve 128 consists of a spool 172 and a spring 173. In addition to the spring 173, the throttle pressure of the circuit 165 and the line pressure of the circuit 156 act on the spool 172 through the spool 174 of the pressure increase valve 129. The resulting force opposes line pressure acting above spool 172 through orifice 172 from circuit 144 and pressure acting from circuit 176. The operating oil pressure of the torque converter 1 is supplied from the circuit 144 to the line pressure regulating valve 128.
The oil introduced into the circuit 145 via the hydraulic oil inflow passage 50 flows into the torque converter 1 and is then removed via the hydraulic oil outflow passage 51 and the pressure holding valve 146. is maintained. Above a certain pressure, the pressure holding valve 146
is opened and oil is further routed from circuit 147 to the rear lubrication section of the drive train. When this lubricating oil pressure is too high, the relief valve 148 opens and the pressure is lowered. On the other hand, the front lubricating section of the power transmission mechanism has circuit 1.
45, the lubricating valve 149 is opened and lubricating oil is supplied. The speed selection valve 130 is a manually operated fluid direction switching valve, and is composed of a spool 150, which is connected to a speed selection rod (not shown) via a linkage, and the spool 150 is actuated by each speed selection operation to control the line. This is for switching the pressure feeding passage of the pressure circuit 144. The condition shown in FIG. 3 is the N (neutral) position, with line pressure circuit 144 open to ports d and e. The first governor valve 113 and the second governor valve 114 are shifted to the 1-2 shift valve 131 and the 2-3 shift valve by the governor pressure generated during forward travel.
The shift valve 132 is actuated to perform automatic gear shifting and also controls the line pressure, and the speed selection valve 130
When is in each position D, and, the oil pressure reaches the second governor valve 114 from the line pressure circuit 144 through port c of the speed selection valve 130, and when the car is running, the pressure is regulated by the second governor valve 114. The governor pressure thus generated is sent to the circuit 157 and the first governor valve 1
13, and when the vehicle speed reaches a certain speed, the spool 177 of the first governor valve 113 moves and the circuit 157
is connected to the circuit 158 to generate governor pressure, and the governor pressure is transferred from the circuit 158 to the 1-2 shift valve 131,
2-3 Shift valve 132 and cut-down valve 13
counterbalanced by respective springs acting on each end face of 4 and urging each of these valves to the right. Also, from port c of speed selection valve 130 to circuit 153 and circuit 16
1 and second brake 1 via circuit 162
Fastening side hydraulic chamber 1 of servo 141 that tightens 06
1-2 shift valve 1 in the middle of the hydraulic circuit reaching 69
31 and a second lock valve 135 are provided separately,
Furthermore, a circuit 152 extending from port b of the speed selection valve 130 to the second lock valve 135 is provided.

Therefore, when the speed selection rod is set to the D position, the spool 150 of the speed selection valve 130 operates and the line pressure circuit 1
44 leads to ports a, b, and c. The hydraulic pressure passes through the circuit 151 from port a, and part of it acts on the lower part of the second lock valve 135, and the spring 17
The spool 178, which is pressed upward by the spool 9, is lowered by the hydraulic pressure acting from the port b through the circuit 152, so that the conductive circuits 161 and 162 are not cut off, and a part of the spool 178 is pressed upward by the orifice 166. From circuit 167 to 2-
3 shift valve 132, and from port c, circuit 1
53 and reaches the second governor valve 114, rear clutch 105 and 1-2 shift valve 131, and the transmission is in the first forward speed. In this state, when the vehicle speed reaches a certain speed, the spool 160 of the 1-2 shift valve 131, which is pressed to the right by the spring 159, moves to the left due to the governor pressure of the circuit 158, shifting from the first forward speed to the second forward speed. When automatic gear shifting is performed, the circuit 153 and the circuit 161 are brought into conduction, and the hydraulic pressure is applied to the second brake 106 which reaches the engagement side hydraulic chamber 169 of the servo 141 from the circuit 162 via the second lock valve 135, and the transmission is engaged. is forward second
Be in a state of speed. In this case, the 1-2 shift valve 13
1 is compact, the spool 160 moves to the left at the required speed without increasing the speed at the shift point, and an automatic shift action from forward first speed to second speed is performed. When the vehicle speed increases further and reaches a certain speed, the governor pressure of the circuit 158 overcomes the spring 163 and becomes 2-
3 Push the spool 164 of the shift valve 132 to the left to connect circuits 167 and 168, and the oil pressure to circuit 1.
Part from 68 is the release side hydraulic chamber 17 of the servo 141
0 and releases the second brake 106,
A portion reaches and engages the front clutch 104, placing the transmission in third forward gear.

Furthermore, when the driver depresses the accelerator pedal until the throttle opening is close to full throttle while driving in the D position, desiring a large acceleration force, the kick-down switch is turned on and the solenoid down shift valve 137 is turned on. A down shift solenoid 137a disposed opposite to the down shift solenoid 137a is energized by energization. As a result, the spool 190 of the solenoid downshift valve 137 is pushed downward by the spring 191 from the upwardly locked position in FIG. At this time, the kickdown circuit 180 that was connected to the circuit 154 is connected to the line pressure circuit 144, and the line pressure is applied to the circuit 14.
4,180 and 1-2 shift valve 131 and 2-
3 shift valve 132 is supplied opposite the governor pressure. At this time, if the vehicle is running in third gear, the spool 164 of the 2-3 shift valve 132 is forcibly pushed by the line pressure from the leftward position to the rightward position against the governor pressure. 3rd within vehicle speed limit
A forced downshift from 1st gear to 2nd gear is performed, and sufficient acceleration force is obtained. By the way, if the above kickdown is performed while driving in second gear,
At this time, the load is large and the speed is low, so the governor pressure is also low, so the line pressure led to the circuit 180 causes the spool 160 of the 1-2 shift valve 131 to also move from the left position to the right against the governor pressure. Ru. Therefore, in this case, a forced downshift from second speed to first speed is performed, and a stronger acceleration force corresponding to a large load can be obtained.

When the speed selection rod is set to the (second forward speed fixed) position, the spool 150 of the speed selection valve 130 moves and the line pressure circuit 144 communicates with ports b, c, and d.
Oil pressure reaches the same locations from ports b and c as in case D, engaging the rear clutch 105, while the lower part of the second lock valve 135 is not receiving oil pressure in this case and the spool 178 circuit. Since the areas of the lands above and below the part that opens at 152 and where hydraulic pressure is applied are larger at the bottom, the spool 178 of the second lock valve 135 is pushed down against the force of the spring 179, and the circuits 152 and 16
2 becomes conductive, the hydraulic pressure reaches the engagement-side hydraulic chamber 169 of the servo 141, engages the second brake 106, and the transmission enters the second forward speed state. From port d, hydraulic pressure passes through circuit 154 to solenoid down.
Shift valve 137 and throttle back up valve 138 are reached. There is a disconnection between port a of the speed selection valve 130 and the line pressure circuit 144, and the hydraulic pressure has not reached the 2-3 shift valve 132 from the circuit 151, so the second brake 106 is released and the front clutch 104 is released. The engagement is not performed and the transmission is not in the third forward speed state, and the second lock valve 135 works in conjunction with the speed selection valve 130 to fix the transmission in the second forward speed state. . When the speed selection rod is set to the (first forward speed fixed) position, the line pressure circuit 144 is connected to ports c, d and e.
Leads to. Hydraulic pressure reaches the same location from ports c and d as in , engaging the rear clutch 105, and from port e via circuit 155 through the 1-2 shift valve 131 and partially from circuit 171 to the low
The low reverse brake 10 reaches the reverse brake 107 and acts as a forward reaction brake.
7, the transmission is in the first forward speed state, and a portion reaches the left side of the 1-2 shift valve 131 and the spring 1
59 to keep the spool 160 pressed to the right, and the first speed is fixed.

In FIG. 3, reference numeral 100 indicates a lock-up control device according to the present invention, which includes a lock-up control valve 30 and a lock-up solenoid 3.
1. Lockup control valve 30, lockup solenoid 31, and lockup mechanism 1
Details of the torque converter 1 with 7 will be explained below with reference to FIG.

The pump wheel 3 of the torque converter 1 is connected via a converter cover 6 to a drive plate 5, which in turn is connected to the engine crankshaft 4. Further, the turbine wheel 8 is splined to the input shaft 7 via a hub 18, and the stator wheel 9 is further connected to the sleeve 12 via a one-way clutch 10. The torque converter 1 is surrounded by a converter housing 28, and the converter housing is connected to the transmission case 29 with the pump housing 1.
4 and pump cover 11. The oil pump 13 is housed in a chamber defined by the pump housing 14 and the pump cover 11, and is coupled to the pump impeller 3 via a hollow shaft 52 so as to be driven by an engine. Hollow shaft 52
The sleeve 12 is wrapped around the sleeve 12 to define the annular hydraulic oil supply passage 50 between the two, and the input shaft 7 is loosely passed through the sleeve 12 to define the annular hydraulic oil discharge passage 51 between the two. to be accomplished. Note that the sleeve 12 is integrally molded with the pump cover 11.

The lockup mechanism 17 has the following configuration. A lock-up clutch piston (direct coupling clutch) 20 is slidably fitted onto the hub 18, and the lock-up clutch piston is housed within the converter cover 6. An annular clutch facing 19 is provided on the surface of the lock-up clutch piston 20 facing the end wall of the converter cover 6, and when this clutch facing contacts the end wall of the converter cover 6, an annular clutch facing 19 is provided on both sides of the lock-up clutch piston 20. Lockup chamber 27 and torque converter chamber 6
3 is defined.

A lock-up clutch piston 20 is drivingly coupled to the turbine wheel 8 via a torsional damper 21. The torsional damper 21 is of a type used in dry clutches, etc., and is composed of a drive plate 23, a torsional spring 24, a rivet 25, and a driven plate 26. An annular member 22 is welded to the lock-up clutch piston 20, and its pawl 22a is drivingly engaged with the notch 23a of the drive plate 23, thereby connecting the driven plate 26 to the turbine wheel 8. The lockup chamber 27 is communicated with a lockup passage 16 formed in the input shaft 7, and this passage is connected to the lockup control device 10 as described below.
Relate to 0.

The lock-up control valve 30 includes a spool 30a, and when the spool is placed in the position shown in the upper half of FIG. 3 by a spring 30b, a port 30d is
30e and functions to communicate port 30d to drain port 30f when spool 30a is placed in the lower half position by hydraulic pressure within chamber 30c. Port 3
0d communicates with the lockup passage 16 via a passage 56, and the port 30e communicates with the torque converter hydraulic oil supply passage 50 via a passage 57 as shown in FIG.
The chamber 30c communicates with the rear clutch pressure passage 153 via a passage 53 as shown in FIG.

An orifice 54 is provided in the middle of the passage 53, and a branch passage 55 is provided in the passage 53 between this orifice and the chamber 30c. The branch passage 55 has an orifice 58 therein and communicates with a drain port 59, and the lock-up solenoid 31 is used to open and close the branch passage 55. For this purpose, the lock-up solenoid 31 has a plunger 31a, which is normally kept in the left half position in FIGS.
When energized, the right half is in the protruding position and the branch passage 55
so that it can be closed.

When the plunger 31a opens the branch passage 55 when the solenoid 31 is deenergized, this branch passage communicates with the drain port 59. At this time, the rear clutch pressure flowing toward the chamber 30c via the passage 53 is extracted from the drain port 59, and the lock-up control valve 30 is operated to connect the port 30d to the port 30d because the spool 30a is set to the upper half position in FIG. 4 by the spring 30b. 3
Connect to 0c. Therefore, the internal pressure of the torque converter led to the passage 57 is transferred to the ports 30e and 30.
d, it is supplied to the lockup chamber 27 through the passages 56 and 16, and the lockup chamber 27 has the same pressure as the converter chamber 63. As a result, the lock-up clutch piston 20 is moved to the right from the position shown in FIG. 1 can perform normal power transmission in the torque converter state.

When the plunger 31a closes the branch passage 55 due to the activation of the lock-up solenoid 31, the passage 53
As the spool 30a moves left from the upper half position to the lower half position in FIG. 4, the lock-up control valve 30 connects the port 30d to the drain port. 3
Connect to 0f. As a result, lockup room 2
7 is lockup passage 16, passage 56, port 3
It communicates with the drain port 30f via 0d and is brought into a pressureless state. Thus, the lock-up clutch piston 20 is moved to the left in FIG.
By being pressed against the end wall of the pump impeller 3 and the turbine runner 8, a locked-up state is obtained in which the pump impeller 3 and the turbine runner 8 are directly connected.

In the present invention, the lock-up solenoid 31 is turned on and off by a microcomputer as shown in FIG. 5, for example. In this figure, 200 is a central processing unit (CPU), 201 is a crystal oscillator,
202 is a read-only memory (ROM), 203 is a random access memory (RAM), and 204 is an input/output interface circuit (I/O), which constitute a microcomputer. CPU2
00 is throttle opening signal 205, vehicle speed signal 20
6, 1-2 shift signal 207, 2-3 shift signal 208, engine speed signal 209 to I/O 20
4, and the calculation results of these input signals are read as a lock-up control signal 210 from the I/O 204 to the lock-up solenoid 31 (Figs. 3 and 4).
(see figure), the torque converter 1 is locked up by turning it on and off.

Note that the 1-2 shift signal 207 and the 2-3 shift signal 208 are the same as the 1-2 shift signal 207 and the 2-3 shift signal 208, respectively, as shown in FIG.
1-2 shift switches 60 and 2 configured by being incorporated into the 2-shift valve 131 and the 2-3 shift valve 132
-3 shift switch 61, which opens and closes depending on the position of valve spools 160, 164, respectively, to signal 20.
Outputs 7,208. For this purpose, fixed contacts 65 and 66 are provided on the side plate 64 so as to directly face the end faces of the valve spools 160 and 164, and these fixed contacts are connected from the side plate 64 to the insulator 6.
7, 68, and the valve spool 160,
164 is returned as a movable contact. shift valve 1
Since 31 and 132 are grounded to the vehicle body, by connecting the fixed contacts 65 and 66 to the power supply +V through the resistor through the lead wire 69, the 1-2 shift switch 60 is activated by the fixed contact 65 and the valve spool 160. Also, a 2-3 shift switch 61 can be constructed by the fixed contact 66 and the valve spool 164, respectively.

As is clear from the above, in the first speed, both the valve spools 160 and 164 are connected to the fixed contacts 65 and 6.
6, the 1-2 shift switch 60 and the 2-3 shift switch 61 output low (L) level signals 207 and 208, respectively. At the second speed, only the valve spool 160 moves to the left in FIG. 6 and separates from the fixed contact 65, and the 1-2 shift switch 60 outputs a high (H) level signal 207. Also, in the third gear, the valve spool 164 is also in the sixth gear.
Moving leftward in the figure and away from the fixed contact 66, the 2-3 shift switch 61 also comes to output an H level signal 208.

The CPU 200 receives a clock signal from the crystal oscillator 201, and outputs the ROM from the ROM at regular intervals of, for example, 100ms.
The program stored in the RAM 202 is executed, and during the execution of the program, necessary data is temporarily stored in the RAM 203 or read from it.

First, the CPU 200 executes a control program (not shown) to calculate the throttle opening degree and vehicle speed obtained from the signals 205 and 206, and from the signals 206 and 20.
From the shift position determined by the combination of levels 7,
Based on the table corresponding to the diagram shown in FIG. 9, it is determined whether the torque converter 1 is in the lock-up areas A, B, C where the lock-up state should be made, or in any other converter area. The control signal 210 is set to the H level to energize the lock-up solenoid 31 to bring the torque converter 1 into the lock-up state as requested, and in the converter region, the lock-up control signal 210 is set to the L level to de-energize the lock-up solenoid 31 to turn the torque converter 1 into the lock-up state. Set to converter state as requested.

The above is the basic lock-up control corresponding to the diagram in FIG. 9, but when changing gears in the lock-up area, the CPU 200 temporarily interrupts the lock-up as follows by executing the control program shown in FIG. 7.

The control program shown in FIG. 7 is repeatedly executed at step 210 by interrupting every fixed time ΔT. First, at step 211, the engine rotation speed Ni is read from the signal 209, and then at the next step 212.
Then, it is determined whether or not a shift is already being performed with a shift command. In making this determination, the gear shift flag, which is turned on as described later when a gear shift command is issued, is turned on.
(OFF) or not.

If the shift flag is OFF and the shift is not in progress, the control proceeds to step 213, and it is determined whether or not there is a shift command based on whether there is a level change in the shift signal 207 or 208. If there is no shift command, the control proceeds to step 213. At 242, the control is terminated,
If there is a shift command (instant t in Figure 8 c), in step 214 the engine speed Ni read in step 211 is used as the previous value for checking the engine speed change trend after the shift command, and also as the actual shift operation. Peak value of engine speed before starting (Fig. 8c)
It is stored as the maximum value Nc for viewing the medium Np ₎ .
The control then proceeds to step 215, where the shift flag is turned ON in response to the shift command.
Then, in step 242, the control ends.

After the shift flag turns ON as described above (after t in Figure 8), step 212 selects step 216, and step 21
In step 6, it is determined whether lockup has already been interrupted. This determination is made based on whether the L/U interruption flag, which turns ON as described later, is ON or OFF when lockup interruption is started. If lockup interruption has not yet started and the L/U interruption flag is OFF, step 217 is selected, and here the engine rotation speed Ni read in step 211 is selected.
and the previous engine speed Nc (step 2 for the first time)
The difference ΔNi from the value stored in step 14 is calculated by Ni-Nc.

In the next step 218, it is determined whether the difference ΔNi is negative or negative (positive), that is, whether the engine speed is decreasing (increasing). If △Ni<0, that is, if the engine speed is increasing, step 219 is selected, and the number of times step 218 determines that △Ni<0 (engine speed is decreasing) is counted. The counter MC is cleared to 0, and in the next step 220, the decreasing flag, which is turned ON as described later when the engine speed starts to decrease, is turned OFF. In the next step 221, since the engine rotation is currently increasing, the engine rotation speed Ni read in this time in step 211 is stored as the maximum value Nc. Therefore, thereafter, the maximum value stored here is used as the previous value Nc in step 217. Control then proceeds to step 242 and ends there.

Step 218 shows △Ni<0, that is, the engine speed is the maximum value last stored in step 221.
If it is determined that the decrease is less than Nc, step 22
2 is selected, and it is determined whether the decreasing flag is ON or not. Since this flag was turned OFF in step 220, step 222 selects step 223 and increments the counter MC by one step. In the next step 224, it is determined whether this counter MC is less than a predetermined value K (for example, 3). If it is above the predetermined value, it is certain that the engine speed is continuously decreasing in accordance with the change trend that should occur with the start of the gear shift (it has reached the instant _t6 in Fig. 8c). After the decreasing flag is turned ON in step 225, the control is terminated in step 242. However, if MC<K, the decrease in the engine speed is not due to the start of the shift, but is due to minute fluctuations, so step 224 skips step 225 and returns to step 242. Terminate control.

When MC≧K and the decreasing flag is turned ON in step 225, step 222 selects step 226. In this step, the engine speed Ni read in step 211 this time and the maximum value Nc last stored in step 221, that is, the instant immediately before the engine speed starts to decrease (immediately before the start of gear shifting) in Fig. 8c. The absolute value of the difference from the reference value N _p at t ₆ |△N| is |Ni
−N _p |, and this is the set value △Ns
Determine whether or not it has been reached.

If |△N|≧△Ns, as is clear from Fig. 8c, the shift start instant _t3 has not been reached.
Control proceeds to step 242 and ends, |△N
If |≧△Ns, the shift start instant _t3 has been reached, so the control proceeds to step 227 and lock-up interruption (OFF) control for preventing shift shock is executed as described below.

That is, in this step 227, the lockup control signal 210 in FIG. 5 is set to L level.
When the u interrupt command is issued and the signal 210 is set to L level, the lock-up solenoid 31 is activated.
As a result of the deenergization of the torque converter 1, the lockup is temporarily interrupted even in the lockup region as described above, and the torque converter 1 is switched to the converter state.

Thereafter, in step 228, an L/U interruption timer is started to measure the lockup interruption time (the elapsed time from instant _t3 in FIG. 8c), and in the next step 229, it is determined that the lockup interruption has started. As shown, the L/U interruption flag is turned ON, and then the control is terminated in step 242.

When the L/U suspension flag is turned ON in step 229 as described above, step 216 determines whether or not the L/U has been suspended based on this flag.
selects step 230. In step 230, it is determined whether the timer started in step 228 indicates a lockup interruption time greater than or equal to the pre-stored lockup interruption time T _' shown in FIG. It is determined whether the elapsed time has reached the instant _t4 at which re-lockup is to be performed. If the lockup has not been reached, lockup should continue to be interrupted, so the control is terminated at step 242, and if it has been reached, the control is continued at step 23.
1, the lockup control signal 2 in FIG.
When the signal 210 goes to the H level, the torque converter 1 is re-locked up as described above by energizing the lock-up solenoid 31, and the torque converter 1 is switched to the lock-up state. .

Control then proceeds sequentially to steps 232 to 235 and ends at step 242;
At step 32, turn off the L/u interruption flag,
In step 233, the shift flag is turned OFF, and in step 234, the decreasing flag is turned OFF.
OFF, and in step 235 the counter MC is
is cleared to 0 to prepare for the next control.

(Effects of the Invention) Thus, as described above, the lock-up automatic transmission of the present invention determines the start of a shift operation based on the change tendency of the engine speed after a shift command, but it is not possible to determine whether this change tendency is caused by the actual start of the shift. Continuing with the shift trend, they match the set number of times K or more, and the engine speed is set value △ with respect to the reference value _Np immediately before the start of gear shifting.
It is determined that the shift has started when the speed exceeds Ns, that is, the engine speed is captured in real time, the start of the shift is determined from this, and the lock-up is interrupted at the time of the shift start determined in this way (t ₃ in c in Figure 8). (OFF), the lock-up interruption start time can always be accurately matched to the shift start time _t3 , which may cause a shift shock caused by the engine racing if it is too early, or if it is too late. It is possible to completely eliminate the problem of a shift shock caused by starting a shift in a locked-up state.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the lock-up type automatic transmission of the present invention, Fig. 2 is a schematic diagram showing the power transmission system of the lock-up type automatic transmission of the present invention, and Fig. 3 is a shift control hydraulic circuit diagram of the automatic transmission. Figure 4 is a detailed sectional view showing the lock-up torque converter of the automatic transmission, Figure 5 is a block diagram of the microcomputer that performs lock-up control of the automatic transmission, and Figure 6 is the shift supply to the microcomputer. A sectional view of a shift valve showing an example of the configuration of a shift switch that emits a signal, FIG. 7 is a flowchart showing a control program of a microcomputer, and FIG. 8a
9 shows an operation time chart using the conventional lock-up control, b shows an operation time chart using the lock-up control previously proposed by the applicant, c shows an operation time chart using the lock-up control of the present invention, and FIG. 9 shows the lock-up area. FIG. 10, a shift pattern diagram of an automatic transmission, is an explanatory diagram for explaining the problems of lock-up control previously proposed by the applicant. 1...Lockup torque converter, 4...
Crankshaft, 5...Drive plate, 6
...Converter cover, 7...Input shaft, 10...One-way clutch, 11...Pump cover, 12...Sleeve, 13...Oil pump, 14...Pump housing, 16...Lock-up passage, 17... Lockup mechanism, 18
...Hub, 19...Clutch facing, 20
... Lockup clutch piston (direct clutch), 21 ... Torsion damper, 27 ... Lockup chamber, 30 ... Lockup control valve, 3
1... Lock up solenoid, 50... Torque converter hydraulic oil supply passage, 51... Torque converter hydraulic oil discharge passage, 53... Rear clutch pressure introduction passage, 54, 58... Orifice, 55...
Branch passage, 57...Torque converter internal pressure introduction passage, 59...Drain port, 60...1-2 shift switch, 61...2-3 shift switch, 6
3...Converter chamber, 64...Side plate,
65, 66... Fixed contact, 67, 68... Insulator, 100... Lockup control device, 104...
...Front clutch, 105...Rear clutch,
106...Second brake, 107...Low reverse brake, 108...One-way brake, 1
10...First planetary gear group, 111...Second planetary gear group, 131...1-2 shift valve, 132...2
-3 shift valve, 160, 164...valve spool,
200... central processing unit (CPU), 201...
...Crystal oscillator, 202...Read-only memory (ROM), 203...Random access memory (RAM), 204...Input/output interface circuit (I/O), 205...Throttle opening signal,
206... Vehicle speed signal, 207... 1-2 shift signal, 208... 2-3 shift signal, 209... Engine rotation speed signal, 210... Lock-up control signal, a... Torque converter input element, b...
Torque converter output element, c... Direct coupling clutch, d... Lock-up torque converter, e...
...Engine, f...Lock-up interruption control means,
g...Shift command detection means, h...Engine rotation speed detection means, i...Engine rotation change tendency calculation means, j...Engine rotation change tendency that should occur when the actual shift starts, k...Setting number of times , l... Gear shift start determining means, m... Engine rotation speed reference value setting means, n... Setting value, o... Direct coupling clutch release timing determining means.

Claims (1)

[Claims] 1 Power from the engine is input through a lock-up torque converter with a built-in direct-coupling clutch that can mechanically directly connect input and output elements as appropriate, and the lock-up torque converter is directly connected even in the lock-up region where the direct-coupling clutch should be engaged during gear shifting. A lock-up automatic transmission equipped with a lock-up interruption control means for bringing the converter into a state in which the clutch is temporarily released, a shift command detection means for detecting a shift command of the automatic transmission, and an engine rotation speed for detecting the engine rotation speed. a detecting means, an engine speed change trend calculation means for calculating a change trend in engine speed from a difference in engine speed at set time intervals after a shift command, and an engine speed change trend in which the change trend should be caused by the actual start of a shift. a shift start determining means that determines that a shift has started when the number of shifts matches a set number of times or more; an engine rotation speed reference value setting means that sets an engine rotation speed immediately before the shift start as a reference value; and a difference between the engine rotation speed and the reference value. 2. A lock-up type automatic transmission, comprising: direct-coupling clutch release timing determining means for instructing said lock-up interruption control means to temporarily release said direct-coupled clutch when the lock-up clutch becomes greater than a set value.