JPS5943665B2 - Lock-up control device for lock-up automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lockup control device for a lockup automatic transmission, and more particularly to a hydraulic lockup control device.

Automatic transmissions generally include a torque converter in a power transmission system for the purpose of increasing transmitted torque or absorbing fluctuations in transmitted torque to reduce vibration.

However, since the torque converter is configured to transfer power between the input element (pump impeller) and the output element (turbine runner) via hydraulic oil, slip between these input and output elements is unavoidable and the power transmission efficiency is reduced. bad.

For this reason, lock-up torque converters have been proposed that do not require an increase in torque and can directly connect the input and output elements at relatively high vehicle speeds where torque fluctuations are not a problem. Lock-up automatic transmissions are used in some vehicles to reduce fuel consumption.

However, this type of automatic transmission has conventionally implemented lock-up control that locks up the torque converter at each shift position or in a relatively high vehicle speed range where the vehicle speed exceeds a set vehicle speed (lock-up vehicle speed) at a specific shift position. In other words, lock-up was determined based only on vehicle speed.

However, in this case, setting the lock-up vehicle speed to a low value will result in poor performance during driving with a large engine load (accelerator pedal depression amount), even though the torque converter is required to have a torque increasing function and a torque fluctuation absorbing function. The torque converter will be locked up, causing problems such as a reduction in driving force on the uphill road and vibration of the vehicle body due to torque fluctuations.

Therefore, in the past, the lock-up vehicle speed had to be set at a fairly high altitude as shown by VH in FIG.

However, if the lock-up vehicle speed is set to a high value in this way, lock-up will not occur in the regular vehicle speed range, and for this reason, conventional lock-up automatic transmissions will not shift from left to right under driving conditions where low vehicle speeds are frequent, such as driving around town. The reality is that it is not possible to expect a significant fuel savings effect.

The present invention proposes that whether or not the torque converter's torque increasing function and torque fluctuation absorbing function are necessary is determined not only by the vehicle speed but also by the engine load. From the viewpoint that the torque converter's torque increasing function and torque fluctuation absorbing function are not required even in a relatively low speed range, and therefore no problem will occur even if the lock-up vehicle speed is set to a low value in a small engine load range.
The present invention proposes a hydraulic lockup control device that is capable of such lockup control.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

In the illustrated example below, a case will be described in which the present invention device is applied to a lock-up automatic transmission in which the torque converter is locked up only in the highest gear (third speed), but the present invention device is not limited to this. Needless to say, the present invention can also be applied to automatic transmissions capable of locking up at each gear stage.

Figure 1 schematically shows the internal power transmission part of a lock-up automatic transmission with three forward speeds and one reverse speed.
A crankshaft 4 driven by a prime mover, a lockup torque converter 1 equipped with a lockup mechanism 17 that will be explained in detail later, an input shaft 7, a front clutch 104, a rear clutch 105, a second brake 106, and a low reverse.・Brake 107
, one-way brake 108, intermediate shaft 109, first planetary gear group 110, second planetary gear group 111, output shaft 112, first governor valve 11λ, second governor valve 114, and oil pump 13.

The torque converter 1 consists of a pump impeller 3, a turbine impeller 8, and a stator impeller 9. The pump impeller 3 is driven by a crankshaft jH, and the torque converter 1 is driven by a crankshaft jH.
The converter hydraulic oil is rotated and torque is applied to the turbine wheel 8 fixed to the 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 forward rotation), but does not allow rotation in the opposite direction (hereinafter referred to as reverse rotation). ing.

The first planetary gear group 110 includes an internal gear 117 fixed to the intermediate shaft 109, a sun gear 119 fixed to the hollow conduction shaft 118, an internal gear 117, and the sun gear 11.
The second planetary gear group consists of a planetary gear 120 consisting of two or more small gears that can rotate and revolve at the same time while meshing with each of the planetary gears 9 and 9, and a planetary gear support 121 that is fixed to the output shaft 112 and supports the planetary gear 120. 1
Reference numeral 11 denotes an internal gear 122 fixed to the output shaft 112, a sun gear 123 fixed to the hollow conduction shaft 118, and two or more small parts that can rotate and revolve simultaneously while meshing with each of the internal gear 122 and the sun gear 123. It is composed of a planetary gear 124 made of a gear, and a planetary gear support 125 that supports the planetary gear 124.

The front clutch 104 is connected to an input shaft 7 driven by a turbine wheel 8 and both sun gears 119, 12.
Hollow conduction shaft 1lER that rotates in unison with 3:
are coupled via a drum 126, and the rear clutch 105
serves to connect the input shaft 7 and the internal gear 117 of the first planetary gear group 110 via the intermediate shaft 109.

The second brake 106 has a hollow transmission shaft 118 (
By winding and tightening the fixed drum 126, both sun gears 119 and 123 are fixed, and the low reverse brake 107 functions to fix the planetary gear support 125 of the second planetary gear group 111.

The one-way brake 108 has a structure that allows the planetary gear support 125 to rotate in the normal direction, but not in the reverse direction.

The first gutter valve 113 and the second governor valve 114 are fixed to the output shaft 112 and generate a governor pressure depending on the 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 via the rear clutch 105.

The internal gear 111 rotates the planetary gear 120 "E".

Therefore, the sun gear 119 is reversed, and the sun gear 12 of the second planetary gear group 111 rotates together with the sun gear 119.
3, the planetary gear 1 of the second planetary gear group 111
24 rotates normally.

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, is rotated in the normal direction, and the reduction ratio of the first forward speed is obtained.

In this condition, the vehicle speed increases and the second brake
6 is engaged, the power from the input shaft 7 passing through the rear clutch 105 is transmitted to the internal gear 117 as in the case of the first speed.

The second brake 106 fixes the drum 126 and acts as a brake to stop the rotation of the sun gear 119.

Therefore, the planetary gear 1 moves around the stationary sun gear 119.
20 revolves around its axis, and therefore the planetary gear support 12
1 and the gear shaft 112 integrated therewith are decelerated, but rotate forward at a faster speed than in the first speed, and the reduction ratio of the second forward speed is obtained.

When the vehicle speed increases and the second clutch 106 is released and the front I clutch 104 is engaged, the power transmitted to the input shaft 7 is transferred to the internal gear via the rear clutch 105. 117, and the other is transmitted to sun gear 119 via 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 forward at the same rotational speed.
You can get it fast.

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, front clutch 104 and low reverse brake 107 are engaged.

The power that has passed from the engine through the torque converter 1 is transferred from the input shaft 7 to the front clutch 104 and to the drum 1.
Sun gear 119, 123 through 26? I will be guided.

At this time, since the planet key J7 rear 125 is fixed by the low reverse brake 10γ, the internal gear 122 is decelerated by the above-mentioned stop rotation of the sun gears 119 and 123 and does not reverse rotation. Output shirt I-112 that rotates together with this internal gear
The reverse reduction ratio can be obtained from .

FIG. 2 shows details of the lock-up torque converter 1 equipped with the lock-up mechanism 17.

The pump wheel 3 of this torque converter 1 is connected to a drive plate 5 via a converter cover 6, and this drive plate 1 is connected to an engine crankshaft 4.

Further, the turbine wheel 8 is spline-coupled to the input shaft 7 via a bub 18, and further, the stator wheel 9
is connected to the sleeve 12 via the one-way clutch 10.

The torque converter 1 is surrounded by a convergence bousing 28, and the converter housing is coupled to the transmission case 29 together with the pump housing 14 and the pump cover 11.

As mentioned earlier, the oil pump 13 is housed in a chamber defined by the pump housing 14 and the pump cover 11, and this pump is coupled to the pump impeller 3 by the central shaft 52 so as to be driven by the engine.

The inner shaft 52 encloses the sleeve 12 to define the annular hydraulic oil supply path 50 between the two, and the input shaft γ is loosely passed through the sleeve 12 to discharge the annular hydraulic oil between the two. A passage 51 is defined.

Note that the sleeve 12 is integrally molded with the pump cover 11.

The lock-up mechanism 17 has the following configuration.

A lock-up clutch piston 20 is slidably fitted onto the bubble 18, and the lock-up clutch piston is housed within the converter cover 6.

An annular clutch facing 1 is provided on the surface of the lock-up clutch piston 20 facing the end wall of the converter cover 6.
9 is provided, and when this clutch facing contacts the end wall of the converter cover 6, the lock-up clutch piston 2
A lock-up chamber 27 and a converter chamber 63 are defined on both sides of 0.

A lock-up clutch screw 20 is drive-coupled to the turbine wheel 8 via a 1-national damper 21.

The torsional damper 21 is of a type used in dry clutches and the like, 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 inserted into the notch 2 of the drive plate 23.
3a and connects the driven plate 26 to the turbine wheel 8.

The lockup chamber 21 is communicated with a lockup passage 16 formed in the input shaft γ, and this passage is associated with the lockup control device 100 of the present invention (see FIG. 3) as described below.

FIG. 3 shows a shift control circuit of the automatic transmission equipped with a lock-up control device 100 of the present invention.
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 136, solenoid down shift valve 137
, throttle back up valve 138, vacuum
Throttle valve 139, vacuum diaphragm 140
, a front clutch 104, a rear clutch 105, a second brake 106, a servo 141, a low reverse brake 107, and a hydraulic circuit network.

The oil pump 13 is driven by the prime mover via the drive shaft 4 and the pump wheel 3 of the torque converter 1, and is constantly pumped from the reservoir 142 to the strainer 14 during engine operation.
3, the oil from which harmful dust has been removed is sucked up and sent to the line pressure circuit 144.

The oil is regulated to a predetermined pressure by the line pressure regulating valve 128 and sent to the torque converter 1 and the 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. Line pressure and circuit 17 in which the resulting force acts above spool 172 from circuit 144 through orifice 175
It resists the pressure acting from 6.

The working oil pressure of the torque converter 1 is determined by the hydraulic oil outflow passage 51 and the pressure holding valve after the oil introduced into the circuit 145 from the circuit 144 via the line pressure regulating valve 128 flows into the torque converter 1 through the hydraulic oil inflow passage 50. 146, the pressure is maintained within a certain pressure by a pressure holding valve 146.

Above a certain pressure, the pressure holding valve 146 is opened and oil is sent further from the circuit 147 to the rear lubrication section of the drive train.

When this lubricating oil pressure is too high, the IJ-F valve 148 opens and the pressure is lowered.

On the other hand, lubricating oil is supplied from the circuit 145 to the front lubricating section of the power transmission mechanism by opening the front lubricating valve 149.

The speed selection valve 130 is a manual fluid direction switching valve, which is constituted by a spool 150, and is connected to a speed selection rod (not shown) via a linkage, and the spool 15 is connected to the speed selection rod (not shown) by each speed selection operation.
0 moves to switch the pressure feeding passage of the line 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 actuate the 1-2 shift valve 131 and the 2-3 shift valve 132 using the governor pressure generated during forward travel to perform an automatic gear change operation, and also control the line pressure. When the speed selection valve 130 is in the U and I positions, 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 governor pressure regulated by the second governor valve 114 is applied to the circuit 1
57 and introduced into the first governor valve 113, and when the vehicle speed reaches a certain speed, the spool 177 of the first governor valve 113
moves, the circuit 157 is brought into conduction with the circuit 158, and governor pressure is generated.
counterbalanced by respective springs acting on each end face of 34 and urging each of these valves to the right.

Also, from port C of speed selection valve 130 to circuit 153 and circuit 1
61 and the second brake 106 via circuit 162
The 1-2 shift valve 131 is installed in the middle of the hydraulic circuit that reaches the tightening side hydraulic chamber 169 of the servo 141 that tightens the servo 141.
A circuit 15 in which a lock valve 135 is provided separately and further reaches a second lock valve 135 from port b of the speed selection valve 130
2 will be provided.

Therefore, when the speed selection rod is set to the D position, the spool 150 of the speed selection valve 130 moves and the line pressure circuit 144 is connected to port a.
, bl and C.

Hydraulic pressure is applied from port a through circuit 151, and a portion acts on the lower part of second lock valve 135, and spool 178, which is pressed upward by spring 179, is actuated by hydraulic pressure from port b through circuit 152. By being lowered, the conductive circuits 161 and 162 are prevented from being cut off, and a part of the circuit 1 passes through the orifice 166.
67 reaches the 2-3 shift valve 132, and from port c it passes through the circuit 153 and reaches the second governor valve 114, rear clutch 105, and 1-2 shift valve 131, and the transmission becomes the first forward speed state. .

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 the automatic gear shifting operation is performed, the circuit 153 and the circuit 161 are brought into conduction, and the oil pressure is transferred from the circuit 162 via the second lock valve 135 to the oil on the engagement side of the servo 141.
Reaching the tenth chamber 169, the second brake 106 is engaged,
The transmission is in the second forward speed.

In this case, ■-2 shift valve 131 is downsized, so the spool 160 moves to the left at the required speed without increasing the speed at the shift point, automatically shifting from 1st gear to 2nd gear. action takes place.

When the vehicle speed increases further and reaches a certain speed, the cover pressure of the circuit 158 overcomes the spring 163 and pushes the spool 164 of the 2-3 shift valve 132 to the left, causing the circuits 161 and 16
8 conducts, and a portion of the hydraulic pressure from the circuit 168 reaches the releasing side hydraulic chamber 170 of the servo 141 and is applied to the second brake 106.
is released, and a portion reaches the front clutch 104 and engages it, putting the transmission in the third forward speed state.

Furthermore, when the driver desires a large acceleration force while driving in the D position and presses the accelerator pedal fully open until V is close to fully open, the kick-down switch is turned on and the solenoid down switch is turned on.

Down shift solenoid 1 installed opposite to the foot valve 137
37a is energized by electricity.

As a result, the spool 190 of the solenoid downshift valve 137 is pushed downward by the spring 191 from the locked upward position in FIG.

At this time, times. Kickdown circuit 1 leading to Route 154
80 leads to line pressure circuit 144, and line pressure is connected to circuit 14.
4° 180, and is supplied to the 1-2 shift valve 131 and the 2-3 shift valve 132 so as to oppose 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. A forced downshift from third gear to second gear is performed within vehicle speed limits, and sufficient acceleration force is obtained.

By the way, if the above-mentioned kickdown is performed while running in second gear, the load is large at this time and the speed is low, so the cabana pressure is also low, so the line pressure led to the circuit 180 is 1.
The spool 160 of the -2 shift valve 131 is also moved from the leftward position to the right against the governor pressure.

Therefore, in this case, a forced downshift from second gear to first gear is performed, and an even stronger acceleration force can be obtained in response to a large load.

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 bc and d.

The oil pressure reaches the same place as in case D from ports b and C, and engages the rear clutch 105, while the lower part of the second lock valve 135 has no oil pressure coming to the bottom of the second lock valve 135 in the case of the spool 178. Since the area of the upper and lower lands of the part that opens to the circuit 152 and where hydraulic pressure acts is larger at the bottom, the spool 178 of the second lock valve 135 is pushed down against the force of the spring 1γ9, and the circuit 152 and The circuit 162 becomes conductive, and 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 resolenoid downshift valve 13γ and throttle back up valve 138.

The line pressure circuit 144 is disconnected between the port A of the speed selection valve 130 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. do.

When the speed selection rod is set to the I (first forward speed fixed) position, the line pressure circuit 144 is connected to ports (portions) c, d, and e.

Hydraulic pressure reaches the same location as in position ■ from ports c and d and engages the rear clutch 105, and from port e it goes from circuit 155 to the 1-2 shift valve 131 and then to circuit 1.
The section from 71 to - reaches the low reverse brake 107, engages the low reverse brake 107 that acts as a forward reaction brake, and puts the transmission in the first forward speed state.
A portion reaches the left side of the 1-2 shift valve 131 and springs 159
At the same time, the spool 160 is pressed to the right, and the first forward speed is fixed.

The lock-up control device 100 of the present invention comprises a third lock-up control valve 30, an engine load response valve 31, and a vehicle speed response valve 32.

The lock-up control valve 30 includes a spool 30a, and when this spool is moved to the upper half position in the figure by a spring 30b, the port 30c is communicated with the port 30d, and the spool is moved to the lower half position in the figure by the hydraulic pressure in the chamber 30e. The drain port 30c functions to communicate with the drain port 30f.

The engine load response valve 31 also includes a spool 31a,
When the spool and spring 31b are placed in the upper half position in the figure, the port 31c is communicated with the port 31d, and the chamber 31
Port 3 when moved to the lower half position in the figure due to the hydraulic pressure in e.
1c to the port 31f.

Furthermore, the vehicle speed response valve 32 has a spool 32a, and when this spool is moved to the upper half position in the figure by a spring 32b, the port 32c is communicated with the port 32f, and the hydraulic pressure in the chamber 32e causes the spool to be moved to the lower half position in the figure. port 32C when
The drain port 32d functions to allow the drain port 32d to communicate with the drain port 32d.

Port 30c of valve 30 is connected to lock-up passage 16 through circuit 33, port 30d is connected to torque converter hydraulic oil supply circuit 145 through circuit 34, and chamber 30e is connected to port 31c of valve 31 through circuit 35.

Port 31d of valve 31 is connected by circuit 36 to port 37 of 2-3 shift valve 132;
When the shift valve spool 164 is in the downshift position shown in the lower half of the figure (when 2nd speed is selected), it communicates with the drain port 38, and when it is in the upshift position shown in the upper half of the figure (when 3rd speed is selected). ) Located in a position communicating with the governor pressure circuit 158.

Further, the chamber 31e of the valve 31 is connected to the throttle pressure circuit 165 by a circuit 39, and the port 1=31f is connected to the port 32c of the valve 32 by a circuit 40.

The port 32 of the valve 32 is connected to the hydraulic circuit 168 to the front clutch 104, and the chamber 32e is connected to the hydraulic circuit 168 to the front clutch 104.
is connected to the circuit 36 through the circuit 42c.

The operation of the lock-up control device 100 of the present invention having the above-mentioned structure will be explained next.

When the engine load is smaller than a certain value, that is, when the amount of depression of the accelerator pedal is small and the throttle opening is less than TH1 in FIG. 4, the throttle pressure (engine load signal pressure) in the circuit 165 corresponding to this throttle opening is ) passes through the circuit 39 to the chamber 31e of the engine load response valve 31.
Even if the throttle pressure is supplied to the spool 31a
The spool 31a cannot be pushed against the spring 31b, and the spool 31a maintains the upper half position in the figure.

In this case, ports 31c and 31d are connected, and circuit 35.3
6 are connected.

Here, if the automatic transmission selects 3rd gear, 2-
The spool 164 of the 3-shift valve 132 is in the upshift position in the upper half of the figure, and the port 37 is connected to the governor pressure circuit 158.
Since the governor pressure (vehicle speed signal pressure) corresponding to the vehicle speed in this circuit is connected to the circuit 36 and 35 from port 31,
The lock-up signal pressure is supplied to the chamber 30ec of the valve 30 through the lock-up signal pressure.

Therefore, if the vehicle speed is lower than the conventional lock-up vehicle speed VH (see FIG. 4), for example, if it is less than the low-load lock-up vehicle speed shown at VL in FIG.
The supplied governor pressure moves the spool 30a to the spring 30.
The spool 30a, which can be pushed against the force b, is kept at the upper half position in the figure.

Therefore, baud) 30c leads to port 30d and circuit 3
3.34 are in communication with each other, the pressure in the torque converter hydraulic oil supply circuit 145 (the pressure in the converter chamber 63) is supplied to the lockup chamber 27c via the circuit 34.33 and the lockup passage 16. This 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. can perform normal power transmission in the converter state.

Note that even under the above state of the valve 31, if the automatic transmission does not select third speed, the valve spool 164 of the 2-3 shift valve 132 is in the downshift position shown in the lower half of the figure, and the port 37 is in the downshift position. is communicated with the drain port 38, so cabana pressure is not supplied to the chamber 30e of the valve 30, and the torque converter 1 is in the converter state at this time as well.

By the way, the vehicle speed is the low load lockup vehicle speed v in Figure 4.
1, the corresponding governor pressure (lock-up signal) causes the spool 30a to move against the spring 3 in the chamber 30e.
0b to move the spool 30a to the lower half position in the figure, the port 30C communicates with the drain port 30f, and the pressure supplied to the lockup chamber 27 as described above is transferred to the lockup passage 16 and the circuit 33. The liquid is extracted from the drain port 30f, and the lock-up chamber 2γ is brought to a pressure-free state.

Thus, the lock-up clutch piston 20 is moved to the left in FIG. A lock-up state is obtained in which the turbine and turbine runner 8 are directly connected.

In other words, while driving in 3rd gear or the selected state, in the small load operating range where the throttle opening is set to TH or less in Fig. 4,
The lock-up state of the torque converter is obtained in region A where the vehicle speed exceeds the value indicated by VL in the figure.

In a large load operating range where the throttle opening is greater than TH in FIG. 4, the corresponding throttle pressure in the chamber 31e of the valve 31 pushes the spool 31a against the spring 31b, causing the spool to Keep port 31 in the lower half position in the figure.
c through port) 31N, and the circuits 35 and 40 are communicated.

On the other hand, governor pressure is introduced into the chamber 32e of the valve 32 via a circuit 42, and this governor pressure exerts a force on the spool 32a toward the left in the figure.

However, if the vehicle speed is lower than the lock-up speed shown by VH in FIG. The port is kept in the upper half position in the figure.
The port 32c is traced to the drain port 32f.

Thus, valve 30e is connected to circuit 35 and ports 31C and 31f.

Drain port 32f via circuit 40 and port 32c
Since the spool 30a of the valve 30 is located in the upper half position in the figure, the torque converter 1 can function in the converter state by the above-described action.

At this point, when the vehicle speed becomes higher than the lock-up vehicle speed vH,
Corresponding governor pressure pushes the spool 32a against the spring 32b in the chamber 32e, placing the spool in the lower half position in the figure and opening the port 32C to the port 32d, between the circuits 40 and 41. is communicated.

Here, if the automatic transmission has selected 3rd gear, circuit 1
As mentioned above, front clutch pressure is generated in 68, and this pressure is applied to circuit 41, ports 32d, 32e1 and circuit 4.
0, passes through ports 31f, 31c and circuit 35 and reaches chamber 30e as a lock-up signal pressure.

Therefore, the front clutch pressure is the line pressure of the automatic transmission and is sufficiently high, and this pressure can sufficiently push the spool 30a against the spring 30b in the chamber 30e. The converter may be placed in lockup.

In other words, while driving with the automatic transmission selecting 3rd gear, in a high-load driving range where the throttle opening is greater than or equal to TH in Figure 4, the vehicle speed will be greater than or equal to the value indicated by VH in Figure 4. In region H, the torque converter can be brought into a lock-up state.

However, if the automatic transmission does not select third gear, no front clutch pressure will be generated in the circuit 168 and this pressure will be supplied to the chamber 30e of the valve 30 even though the valve 32 is in the above state. In other words, the torque converter 1 is not put into the lock-up state but is put into the converter state.

Note that in the above example, the above lock-up control is performed only at the highest gear (3rd gear), but if you want to perform the same lock-up control at each gear, you can adjust the throttle pressure and each gear to The device of the present invention can be applied based on the same concept by directing the governor pressure and clutch pressure from the corresponding speed change shift valve.

Thus, the device of the present invention, for example, with the above-mentioned configuration, locks up even at vehicle speeds between v1° and vI□, which conventionally locks up only in the region of vehicle speed VH or higher in FIG. It is possible to increase the speed up to the vehicle speed, thereby making it possible to significantly improve the effect of improving fuel efficiency through lock-up.

Moreover, in the present invention, vehicle speed v1. - VH lock-up, the torque converter's torque increase function, and torque fluctuation absorption function are configured to be performed only in the small engine load range where they are not required. The above effects can be achieved while preventing the inconvenience of vibration.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram showing the power transmission system of a lock-up automatic transmission, Fig. 2 is a detailed cross-sectional view of the lock-up torque converter, and Fig. 3 is a diagram showing the lock-up control device of the present invention. FIG. 4 is a shift pattern diagram of the automatic transmission showing a lock-up region according to the present invention. 1...Torque converter, 4...Crankshaft, 5...Drive plate, 6...
...Converter cover, 7...Input shaft, 10...One-way clutch, 1
1...Pump cover, 12...Sleeve, 13...Oil pump, 14...
Pump housing, 16...Pump-up passage,
17...Lock-up mechanism, 18...
Bub, 19...Clutch facing, 20.
...Lock-up clutch piston, 21...
... Torsion damper, 27 ... Lock-up chamber, 30 ... Lock-up control valve, 31.
...Engine load response valve, 32...Vehicle speed response valve, 50...Torque converter hydraulic oil supply passage, 51...Torque converter hydraulic oil discharge passage , 63... Convergence chamber, 100... Four lock-up control devices of the present invention, 104... Front clutch, 132... 2-3 shift valve, 158
... Governor pressure circuit, 164 ... Valve spool, 165 ... Throttle pressure circuit, 168.
...Front clutch pressure circuit.

Claims (1)

[Claims] 1. A lock-up automatic transmission equipped with a lock-up torque converter in the power transmission system, and a lock-up control valve that can put the torque converter into a lock-up state with its input and output elements directly connected in response to a lock-up signal pressure above a certain level. In response to the engine load signal pressure,
an engine load response valve that supplies vehicle speed signal pressure as the lockup signal pressure to the lockup control valve in a small engine load range; and a vehicle speed response valve that outputs a corresponding high pressure, the lockup type automatic transmission being operable to switch so that the high pressure from the engine load response valve is supplied to the lockup control valve as a lockup signal pressure. Lockup control device.