JPS641701B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a system for changing gears by controlling the switching of a shift valve based on a pilot signal generated by the switching action of a solenoid valve controlled by an electronic control device. The present invention relates to a control device for an automatic transmission.

(Prior Art) Conventionally, automatic transmission control devices have been used for low-speed transmission systems, which change gears by controlling shift valves based on pilot signals generated by the switching action of solenoid valves controlled by electronic control devices. A pressure chamber is configured at at least one end of a shift valve that selectively connects the interposed friction element and the friction element interposed in the high-speed transmission system to the working hydraulic pressure source and the discharge passage through a throttle. and when the solenoid valve is closed, line pressure is introduced into the pressure chamber through the throttle, and when the solenoid valve is opened, the pressure oil in the pressure chamber is discharged, thereby driving the shift valve to change gears. There are some that are made to perform actions.

In an automatic transmission control device having such a configuration,
In order to make the electromagnetic valve as small and as low in power as possible, it is preferable to have a structure in which the valve element is attracted and opened when energized, that is, when it is energized.
In order to deal with failures such as disconnection of the electromagnetic valve, it is necessary to design the motor so that it can be energized during the first speed (low speed) to discharge the pressure oil.

However, on the other hand, automatic transmissions are usually configured in combination with a torque converter, and the torque amplification effect of the torque converter is greater at lower speeds, so in any automatic transmission, line pressure must be increased at low speeds or when starting. It has a built-in pressure regulating system.

This means that a solenoid valve is installed to release pressure during the first gear, when the pressure should originally be high.
In order to obtain the necessary pressure oil at the low speed or when starting, it is necessary to increase the capacity of the hydraulic pump. Moreover, as the number of gears increases, the number of solenoid valves also increases, and accordingly, the capacity of the hydraulic pump must be increased, leading to an increase in the size and cost of the hydraulic pump.

Therefore, in order to reduce pressure oil leakage (relief) loss due to the solenoid valve, the applicant installed a pressure reducing valve between the line pressure and the solenoid valve, so that the line pressure would be reduced to high pressure (approximately Even if the pressure exceeds 15 atm, the solenoid valve system including the throttle always maintains low pressure (approximately 4 atm).
We have proposed a control device that reduces loss of pressure oil by supplying an operating pressure suppressed to 5 atm.

(Problem to be Solved by the Invention) However, in such a control device, theoretically, as described above, by setting the supply pressure to the solenoid valve system to approximately 1/4 of the line pressure, the leakage loss can be reduced to about half of the conventional one. However, it is desirable to further suppress the leakage loss of pressure oil.

The present invention has been made in view of the above-mentioned points, and provides an automatic transmission capable of reducing leakage loss of pressure oil to almost zero when high line pressure is required such as during a stall. The purpose is to provide a control device for

(Means for Solving the Problems) In order to achieve the above object, the automatic transmission control device of the present invention controls the friction elements interposed in the low-speed transmission system and the friction elements interposed in the high-speed transmission system by hydraulic pressure. A pressure chamber connected to the hydraulic pressure source via a throttle is formed at at least one end of a shift valve selectively connected to the source and the discharge path, and when the low-speed transmission system is established, the pressure chamber is connected to the hydraulic pressure source through a throttle. In the control device for an automatic transmission, the automatic transmission is connected to the discharge passage via a solenoid valve, and the pressure chamber is connected to the pressure chamber and the hydraulic pressure source to change the pressure supplied to the pressure chamber depending on the vehicle speed. A regulator valve that regulates the pressure oil of the hydraulic pressure source to a predetermined line pressure;
a governor valve that is supplied with pressure oil from the regulator valve and outputs pressure oil according to the vehicle speed; and a manual shift that is supplied with pressure oil from the regulator valve and is connected to the shift valve to establish a desired speed ratio. and a pressure reducing valve that regulates the maximum value of pressure oil output from the governor valve to a substantially constant value lower than the line pressure and is connected to the shift valve and the solenoid valve, respectively. It is characterized by:

(Function) When the vehicle speed is above a certain speed, the same pressure as the maximum pressure specified by the pressure reducing valve is generated in the pressure chamber of the shift valve, and when the vehicle speed is below the above-mentioned certain speed, the same pressure as the output pressure of the governor valve is generated. Hydraulic pressure is generated in the pressure chamber. Since the governor pressure is proportional to the square of the vehicle speed, the loss flow rate of the pressure oil that is discarded via the solenoid valve is proportional to the vehicle speed until the vehicle speed reaches a certain value, and becomes constant when the vehicle speed exceeds a certain value. .

(Example) An example of the present invention will be described below in detail based on the accompanying drawings.

FIG. 1 shows a schematic diagram of an automatic transmission for a vehicle to which the present invention is applied, and the output of the engine 1 is a hydraulic torque converter (hereinafter simply referred to as a torque converter).
10 pump impellers 12 and further hydrodynamically to a turbine impeller 14. There is a relative speed between these two impellers 12 and 14, and when there is a torque amplification effect, the reaction force is transferred to the stator 1.
6 will bear the burden. A gear 13 is provided on the pump impeller 12, and a hydraulic pump 50 shown in FIG. 2 is driven via this gear 13. Also, the stator 16
When the reaction force exceeds a certain value, the stator shaft 17 rotates, and the arm 17a at its tip presses the regulator valve 51 shown in FIG. 2, thereby increasing the line pressure, that is, the discharge pressure of the hydraulic pump 50. It will be done.

A direct coupling clutch Cd is provided between the pump impeller 12 and the turbine impeller 14. This direct coupling clutch Cd is constructed as shown in FIG. The peripheral wall 14a has a driven conical surface 4 facing parallel to the driving conical surface 2 on the outer periphery.
A driven member 5 is spline-fitted to be slidable in the axial direction. A piston 6 is integrally formed at one end of the driven member 5, and this piston 6 is slidably connected to a hydraulic cylinder 7 provided on the inner circumferential wall 14a of the turbine impeller 14, and the internal pressure of the cylinder 7 and the internal pressure of the torque converter 10 are and is received on both the left and right sides at the same time.

A cylindrical clutch roller 8 is interposed between the driving and driven conical surfaces 2 and 4, and the center axis of the clutch roller 8 is aligned with the generatrix of an imaginary conical surface passing through the center between both the conical surfaces 2 and 4. It is held by an annular retainer 9 so as to be tilted with a predetermined accuracy. When the torque amplification function of the torque converter 10 is no longer necessary, if hydraulic pressure higher than the internal pressure of the torque converter 10 is introduced into the hydraulic cylinder 7, the piston 6, that is, the driven member 5 is pushed in the direction of the driving member 3. As a result, the clutch roller 8 is brought into pressure contact with both the conical surfaces 2 and 4. At this time, when the drive member 3 acts to drive the driven member 5 due to the output torque of the engine 1 (a load is applied to the torque converter), the clutch roller 8 rotates and causes the members 3 and 5 to approach each other. gives a relative axial displacement such that As a result, the clutch roller 8 bites into the space between the two conical surfaces 2 and 4, mechanically connecting the two members 3 and 5, that is, the pump impeller 12 and the turbine impeller 14.

Even when the direct coupling clutch Cd is operated,
If the output torque of the engine 1 acts between the impellers 12 and 14 in excess of the coupling force, the clutch roller 8 will slip on the respective conical surfaces 2 and 4. As a result, the torque is divided into two parts, and a part of the torque is mechanically transmitted through the direct coupling clutch Cd.
The remaining torque is hydrodynamically transmitted via both impellers 12 and 14, forming a variable rate power split system in which the ratio of the former torque to the latter torque changes depending on the degree of slippage of the clutch roller 8. .

When a reverse load is applied to the torque converter 10 while the direct coupling clutch Cd is in operation, the rotational speed of the driven member 5 becomes higher than the rotational speed of the driving member 3, and the clutch roller 8 rotates in the opposite direction to that described above. A relative axial displacement is applied to both members 3, 5 so as to separate them from each other. As a result, the clutch roller 8 is released from being wedged between the conical surfaces 2 and 4, and becomes idling. The transfer of the reverse load from the turbine impeller 14 to the pump impeller 12 therefore takes place only hydrodynamically.

When the hydraulic pressure of the hydraulic cylinder 7 is released, the piston 6 receives the internal pressure of the torque converter 10 and retreats to its initial position, and the direct coupling clutch Cd becomes inactive.

Returning to FIG. 1, the output shaft 18 of the torque converter 10 also serves as the input shaft of the auxiliary transmission 20.
A third speed drive gear 22, a second speed clutch _C2 , and a first speed clutch _C1 are mounted on this output shaft, that is, the input shaft 18 of the auxiliary transmission 20, in order from the left in the figure.
Furthermore, a second speed drive gear 24 and a first speed drive gear 26 are loosely fitted onto the input shaft 18, and rotate together with the input shaft 18 when both clutches C ₁ and C ₂ are engaged. The second speed drive gear 24 has a reverse drive gear 25.
are integrally provided.

A countershaft 30 parallel to the input shaft 18 has a spline that selectively engages with a final drive gear 32, a third speed clutch _C3 , a second speed driven gear 34, or a reverse driven gear 35 in order from the left in FIG. S, and a first speed driven gear 36 are attached. A one-way clutch _C4 is interposed between the first speed driven gear 36 and the countershaft 30, and transmits torque only in the direction of the driving torque from the engine 1. Further, a third speed driven gear 38 that rotates integrally with the third speed clutch C ₃ and the countershaft 30 is loosely fitted into the countershaft 30 .
The two reverse gears 25 and 35 are idle gears I
are interlocked with each other through.

The driving torque of the final drive gear 32 is transmitted to the final driven gear 40, and is further transmitted to the left and right driving wheels via a differential gear 42 that is integral with the final driven gear 40.
It is transmitted to WL and WR. When reversing, the selector sleeve 44 on the countershaft 30 is shifted to the right by a shift fork (not shown), and the countershaft 30 and the reverse driven gear 35 are
and the second speed clutch.
Engage C ₂ . As a result, the reverse torque is shifted to the left.
It is transmitted to the right drive wheels WL and WR.

FIG. 2 shows a block diagram of a control device for the direct coupling mechanism of torque converter 10 shown in FIG. In addition, in FIG. 2, only the first speed and second speed clutches are shown for convenience of explanation.

In FIG. 2, the hydraulic pump 50 is connected to ports 51b and 51 of the regulator valve 51 via an oil passage 70.
c and are connected to the input port 53a of the manual shift valve 53 via an oil passage 72, respectively. The port 51c of the regulator valve 51 is connected to the input port 52a of the governor valve 52 via an oil passage 71, and the output port 52b of the governor valve 52 is connected to the input port 54b of the pressure reducing valve 54 via an oil passage 73. . Port 51e of regulator valve 51, port 52c of governor valve 52, and port 5 of pressure reducing valve 54
4d are connected to the tank 58, respectively. Furthermore,
The output port 51d of the regulator valve 51 is connected to the torque converter 10 through an oil passage 85 and a throttle 94.
is connected to port 10a of.

The output port 53b of the manual shift valve 53 is
1-2 shift valve 55 via oil passage 74 and throttle 91
is connected to the port 55b of the oil passage 7.
5 and a throttle 90 to the first gear clutch C ₁ (low clutch). 1-2 shift valve 5
The output port 55c of No. 5 is connected to the second speed clutch C ₂ (high clutch) through the oil passage 76, and the output port 55c of the No.
55e are connected to tanks 58, respectively.

The output port 54c of the pressure reducing valve 54 is connected to the port 55e of the 1-2 shift valve 55 and the input port 56c of the pilot type solenoid valve 56 via the oil passage 77 and the throttle 92, respectively. The output ports 56d of are connected to the tanks 64, respectively.

The output port 51d of the regulator valve 51 includes an oil passage 79, a timing valve 59, and a modulator valve 60.
and the port 61b of the lock-up control valve 61 via the oil passage 80, and the port 61c via the throttle 93.
are connected to each other. The spool end face 59a side of the timing valve 59 is connected to the oil passage 76 via the pilot passage 83, and the spool end face 60a side of the modulator valve 60 is connected to the oil passage 80 via the oil passage 84.
The spool end face 60b side is connected to the downstream side of the modulator valve 60 and the upstream side of the lock-up control valve 61 via a pilot passage 82. Oil lines 88 and 89 to which these lock-up control valves 59 and modulator valves 60 are connected
is connected to tank 58.

Input port 57c of pilot type solenoid valve 57
is connected to the pressure chamber 61f of the lock-up control valve 61 via the oil passage 81, and the output port 57d is connected to the tank 58.
are connected to each other. Furthermore, the output port 61d of the lock-up control valve 61 is connected to the port 10b of the torque converter 10 via an oil passage 86. Also, port 1 of the torque converter 10
0c is connected to the tank 5 via the oil passage 87 and the check valve 62.
8 is connected. Solenoids 56a and 57a of electromagnetic valves 56 and 57 are connected to electronic control circuit 10, respectively.
Connected to 0.

The vehicle speed sensor 101 detects the vehicle speed, outputs a corresponding vehicle speed signal, for example, a pulse signal with a period corresponding to the vehicle speed, and supplies the signal to the electronic control device 100. The throttle opening sensor 102 is connected to a throttle valve (not shown), outputs a throttle opening signal corresponding to the opening of the throttle valve, and supplies the signal to the electronic control unit 100.

As shown in FIG. 3, the electronic control device 100 is equipped with a lock-up schedule map determined by the vehicle speed V and the throttle opening θ. , a solenoid valve 56 for speed change and a solenoid valve 5 for lock-up according to the operating state.
7 is driven and controlled. That is, the electronic control device 100
The system determines whether the operating state is in the left or right region of the schedule map shown in the dashed line in Fig. 3, and when it is in the left region, it outputs a solenoid valve drive signal and operates the solenoid valve. The valve 56 is energized, and when it is in the right region, the solenoid valve 56 is deenergized.

Furthermore, it is determined whether the operating state is in the left or right region of the lock-up schedule map indicated by a solid line on the schedule map, and when the operating state is in the left region, a solenoid valve drive signal is output to activate the solenoid valve 57. When the solenoid valve 57 is energized and in the right region, the solenoid valve 57 is deenergized. These solenoid valves 5
6 and 57 open when energized and close when deenergized.

These vehicle speed sensor 101, throttle opening sensor 102, electronic control circuit 100, etc. are well known, and their details will be omitted.

The operation of the automatic transmission control device configured as described above will be explained below.

First, the pressure oil pressurized by the hydraulic pump 50 is adjusted to a predetermined level (line pressure) by the regulator valve 51.
After the pressure is regulated, it is supplied to the governor valve 52 and manual shift valve 53, and the governor valve 52 outputs pressure oil according to the vehicle speed. When the manual shift valve 53 is operated to shift to a drive range (D range (not shown)), the oil passage 74 is connected to the hydraulic pump 50, and the first speed clutch (low clutch) _C1 is pressurized and engaged to shift to the first speed. A speed ratio of is established. The characteristic of the line pressure P at the time of starting is shown by the solid line in FIG.

The governor valve 52 is driven at a rotational speed proportional to the vehicle speed, and its centrifugal force outputs pressure oil Pgo in a magnitude proportional to the square of the vehicle speed to the oil passage 73, as shown by the broken line in FIG. This pressure oil is input to the pressure reducing valve 54, and after its maximum value is regulated, it is guided to the pressure chamber 55f at the right end of the 1-2 shift valve 55 via the oil passage 77 and the throttle 92. The pressure reducing valve 54 is the most common one, and receives its output pressure on the right end surface of the spool 54a, and when the output pressure reaches a specified value, the input port 5
4b and operates to prevent the output pressure from exceeding the specified pressure. The output pressure characteristic of this pressure reducing valve 54 is the fifth
Indicated by the solid line in the figure.

At this time, if the solenoid valve 56 is energized, the valve body 5
6a is opened and sucked into the illustrated position, and input port 56c is opened. Therefore, all the pressure oil flowing through the throttle 92 is returned to the tank 58 through the output port 56d. As a result, pressure oil is not supplied to the pressure chamber 55f of the 1-2 shift valve 55,
The spool 55a of the 1-2 shift valve 55 is pushed to the right end as shown in the figure by spring pressure. Therefore,
The 1-2 shift valve 55 is in a closed state, and the vehicle speed is maintained at the speed ratio of the first speed (low speed). In this way, a low speed transmission system is established.

When the electromagnetic valve 56 is deenergized, the valve body 56b is closed and the input port 56c is closed, and all the pressure oil flowing through the throttle 92 is supplied into the pressure chamber 55f of the 1-2 shift valve 55. As a result, the pressure oil introduced into the pressure chamber 55f of the 1-2 shift valve 55 pushes the spool 55a to the left in the figure against the spring force, and accordingly, the input port 55b and the output port 55c communicate with each other. The pressure oil in the oil passage 74 is restricted to the throttle 91, 1-2.
The oil is supplied to the second speed clutch (high clutch) _C2 via the shift valve 55 and oil passage 76, and the second speed clutch 57 is engaged under pressure. The first automatic transmission
The one-way clutch _C4 (first
) is provided, and this one-way clutch
C ₄ establishes the second speed ratio (high speed) even when the first speed clutch C ₁ is engaged. In this way a high speed transmission system is established.

By the way, the pressure chamber 55f of the 1-2 shift valve 55
As shown in FIG. 5, when the vehicle speed is above a certain vehicle speed Vm, the hydraulic pressure P generated in The pressure is the same as Pgo. Therefore, the lower the vehicle speed, the more the pressure chamber 5
The oil pressure of the pressure oil supplied to 5f also becomes low. Therefore, even if the solenoid valve 56 is open, the flow rate of the pressure oil discarded from the solenoid valve 56 via the throttle 92, that is, the flow rate Q of the pressure oil returned to the tank 58, will be the square root of the governor pressure Pgo. It decreases proportionally with decreasing vehicle speed.

On the other hand, as mentioned above, the governor pressure Pgo is 2 times the vehicle speed.
In the end, the throttle 92 and the solenoid valve 5
The loss flow rate of the pressure oil that is discarded through 6 is proportional to the vehicle speed up to the vehicle speed Vo, and becomes constant above the vehicle speed Vo. The flow rate Q of the pressure oil that is returned to the tank 58 via the solenoid valve 56 while the solenoid valve 56 is energized is shown by the broken line in FIG.

Therefore, even when the stator arm 17a presses the valve body 51a of the regulator valve 51 to the left in the figure against the spring force at a vehicle speed of 0, such as when starting, the pressure oil It becomes possible to obtain a system that can theoretically suppress the leakage loss to zero.

Now, the governor pressure Pgo of the governor valve 52 is also operated to increase the engagement force of the lockup of the direct coupling mechanism in response to the vehicle speed. That is, the regulator valve 5
1, the excess pressure oil is sent to the oil passage 79, and a part of it is supplied into the torque converter 10 via the oil passage 85, the throttle 94, and the port 10a of the torque converter 10.
After being used for cooling the oil passage 87 and the check valve 6
2 to the tank 58, and the rest is a timing valve 59 for temporarily releasing the lock-up during gear shifting, a modulator valve 60 that increases the lock-up engagement force in response to vehicle speed, an input port 61b of the lock-up control valve 61, and the throttle. 93 respectively to the port 61c.

When the solenoid valve 57 is deenergized, it is closed and the lock-up control valve 61 is closed via the throttle 93.
The pressure oil introduced into the pressure chamber 61f presses the spool 61a to the left in the figure against the spring force, thereby communicating the input port 61b and the output port 61d. As a result, the pressure oil in the oil passage 80 is released from the lock-up control valve 6.
1. The oil is introduced into the cylinder 7 of the torque converter 10 through the oil passage 86 and the port 10b of the torque converter 10, and the driven member 5 is connected to the drive member 3.
to lock up the torque converter 10.

When the solenoid valve 57 is energized and opened, the pressure oil introduced into the pressure chamber 61f of the lock-up control valve 61 is returned to the tank 58 via the solenoid valve 57, and as a result, the pressure of the lock-up control valve 61 is The spool 61a is pushed to the right end by the spring force as shown in the figure, thereby closing the valve. As a result, the supply of pressure oil to the cylinder 7 of the torque converter 10 is stopped, and the lock-up of the torque converter 10 is released. That is, the lock-up control valve 61 is the solenoid valve 5.
Turns off (valve closed) when 7 is energized, and turns on (valve open) when deenergized.
When the torque converter is turned on, the torque converter 10 is locked up, and when it is turned off, the lockup is released.

The solenoid valve 57 is energized only when the operating state is to the left of the lock-up schedule shown by the solid line in FIG. 3, and therefore the time during which it is energized is very short compared to the running time.

The timing valve 59 operates when pressure oil is not supplied to the oil passage 76, that is, when the 1-2 shift valve 55 is closed as shown in the figure and only the first speed clutch _C1 is engaged under pressure, the speed of the first speed is maintained. When the ratio is established, the position is switched to the illustrated position 59A by the spring force, the solenoid valve 56 is closed, the 1-2 shift valve 55 is opened, and pressure oil is supplied to the oil passage 76. At this time, this pressure oil is supplied to the timing valve 59 via the oil passage 83. As a result, the spool is pressed against the spring force and is switched from the stop position 59B to the position 59C. That is, the second gear clutch
When C ₂ is engaged under pressure, it is switched to the stop position 59B and the supply of pressure oil to the lock-up control valve 61 is temporarily stopped, and when the engagement of the second speed clutch C ₂ is completed, it is switched to the stop position 59B. The lock-up of the torque converter 10 during gear shifting is temporarily released.

The modulator valve 60 is activated when the vehicle speed is low and the governor pressure is low.
When Pgo is low, it is switched to position 60B by spring force, and the governor pressure Pgo is adjusted according to the vehicle speed.
becomes higher, it resists the spring force and moves to the illustrated position 60A.
is switched to. When the solenoid valve 57 is energized and opened as shown, the pressure oil introduced into the pressure chamber 61f of the lock-up control valve 61 via the oil passage 80 and the throttle 93 flows through the solenoid valve 57. The water is returned to the tank 58 and the lock-up control valve 61
The spool 61a is pressed to the right end position shown in the figure by a spring force, and the valve is closed. The governor pressure Pgo of the governor valve 52 changes as shown by the broken line in FIG.
The lockup pressure Plc of the torque converter 10 changes as shown by the solid line in the figure.

The electronic control circuit 100 further determines that when the torque converter 10 is locked up, the vehicle speed decreases in an inconvenient driving region, for example, when the accelerator pedal is returned to the idle position while driving, or when a high gear is established. (At this time, the engine speed is decreasing.) When so-called muffled noise is likely to occur, that is, when the lock-up schedule map is in the region on the left side of the lock-up schedule map shown by the solid line in FIG. 3, the solenoid valve 57 is energized. Torque converter 10
release the lockup.

Furthermore, when starting, the governor pressure Pgo is low and the modulator valve 60 is switched to the position 60A.
Although the lock-up basically does not function, in order to more reliably release the lock-up, it is preferable to energize the solenoid valve 57 and close the lock-up control valve 61 up to a certain vehicle speed. In this lock-up release, the lock-up operating pressure corresponding to the governor pressure Pgo is applied to the solenoid valve 5 through the throttle 93.
7, the loss of pressure oil returned to the tank 58 via this electromagnetic valve 57 is so small that it can be ignored at the time of starting and at extremely low speeds.

When the lockup is operating, the solenoid valve 5
7 is closed, so that the lockup engagement force is not lost in any way and the exact engagement force defined by the modulator valve 60 is transmitted to the lockup servo system. Even in the unlikely event that the solenoid valve 57 has a failure such as disconnection, the lock-up engagement force will weaken as the vehicle speed decreases, as shown in FIG. Pt becomes higher than lockup pressure Plc, and lockup is released. Therefore, even if the vehicle stops, the engine is prevented from stopping.

Therefore, even if the electromagnetic valve 57 should close due to disconnection, engine stoppage can be avoided, and the life of the electromagnetic valve can be significantly extended.

(Effects of the Invention) As explained above, the present invention provides a shift valve that selectively connects a friction element in a low-speed transmission system and a friction element in a high-speed transmission system to a hydraulic pressure source and a discharge path. A pressure chamber is configured at at least one end to be connected to the hydraulic pressure source through a throttle, and the pressure chamber is connected to the discharge passage through a solenoid valve when the low-speed transmission system is established. In the automatic transmission control device according to the present invention, a vehicle speed-responsive supply pressure means is interposed between the pressure chamber and the hydraulic pressure source to change the supply pressure to the pressure chamber according to the vehicle speed, and the vehicle speed-responsive supply pressure means The supply means includes a regulator valve that regulates the pressure oil of the hydraulic pressure source to a predetermined line pressure, a governor valve that is supplied with pressure oil from the regulator valve and outputs pressure oil according to the vehicle speed, and a governor valve that outputs pressure oil according to the vehicle speed from the regulator valve. A manual shift valve is supplied with pressure oil and is connected to the shift valve to establish a desired speed ratio, and a maximum value of pressure oil output from the governor valve is regulated to a substantially constant value lower than the line pressure. The present invention is characterized in that it is comprised of a pressure reducing valve connected to the shift valve and the electromagnetic valve, respectively.

Therefore, line pressure is introduced into the pressure chamber of the shift valve via the governor valve and the pressure reducing valve to operate the shift valve, so high line pressure is required such as when stalling. It is possible to reduce leakage loss of pressure oil to almost zero in such cases, and as a result, the capacity of the hydraulic pump, which is the hydraulic pressure source, can be reduced, thereby reducing the size and cost of the control device. It has the following effects:

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an automatic transmission to which the present invention is applied, Fig. 2 is a block diagram showing an embodiment of an automatic transmission control device according to the present invention, and Fig. 3 is an implementation of a lock-up schedule map. Figure 4 is a characteristic diagram showing the relationship between vehicle speed and line pressure, Figure 5 is a characteristic diagram showing the relationship between vehicle speed, pressure of the pressure reducing valve, and leakage loss flow rate of the solenoid valve, and Figure 6 is a diagram showing an example. The figure is a characteristic diagram showing the relationship between vehicle speed and oil pressure in each part of the control device shown in FIG. 2. 1...engine, 10...torque converter,
12... Pump impeller, 14... Turbine impeller, 18... Output shaft, 20... Auxiliary transmission,
WL, WR...Drive wheel, 50...Hydraulic pump, 5
1...Regulator valve, 52...Governor valve, 53
...Manual shift valve, 54...Pressure reducing valve, 55...
...1-2 shift valve, C ₁ , C ₂ ... clutch, 56,
57... Solenoid valve, 59... Timing valve, 60...
... Modulator valve, 61 ... Lockup control valve, 100 ... Electronic control circuit, 101 ... Vehicle speed sensor, 102 ... Throttle sensor.

Claims (1)

[Claims] 1 At least one end of a shift valve that selectively connects a friction element interposed in a low-speed transmission system and a friction element interposed in a high-speed transmission system to a hydraulic pressure source and a discharge passage is connected to the hydraulic pressure source through a throttle. In the control device for an automatic transmission, the pressure chamber is connected to the discharge passage via a solenoid valve when the low-speed transmission system is established. A vehicle speed-responsive supply pressure means for changing the pressure supplied to the pressure chamber according to the vehicle speed is interposed between the hydraulic pressure source and the hydraulic pressure source, and the vehicle speed-responsive supply pressure means changes the pressure oil of the hydraulic pressure source. a regulator valve that regulates line pressure to a predetermined line pressure; a governor valve that is supplied with pressure oil from the regulator valve and outputs pressure oil according to vehicle speed; and a governor valve that is supplied with pressure oil from the regulator valve and is connected to the shift valve. with a manual shift valve to establish the desired speed ratio;
A maximum value of pressure oil output from the governor valve is regulated to a substantially constant value lower than the line pressure, and the pressure reducing valve is configured to be connected to the shift valve and the solenoid valve, respectively. automatic transmission control device.