JPH0328605B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a hydraulic pressure control device for controlling a hydraulic clutch for a power shift type transmission of a vehicle.

For example, as shown in FIG. 1, this type of conventional device is equipped with a directional control valve 3 that receives pressurized fluid from a pump 2 whose pressure is limited by a pressure control mechanism 1, and is installed in a plurality of gear trains of a transmission. Among the hydraulic clutches 4, 5, and 6, for example, the pump pressure fluid is introduced to the clutch cylinder 7 of the clutch 4 of the clutch-off state, and the stop cylinder 8 of the clutch 6 of the clutch-on state is communicated with the tank 9. As a result, the clutch 4 is turned on by the pressure fluid filled in the clutch cylinder 7, and the clutch 6 is turned off as the pressure in the clutch cylinder 8 decreases as shown by the broken line in FIG.

The pressure control mechanism 1 includes a relief valve 10 and a cylinder 1 that adjusts the force of a spring 11 that determines its set pressure.
2 and a throttle 13 with a check valve, and operates as follows. When an empty clutch cylinder, for example, the clutch cylinder 7, is filled with pressure fluid, the supply fluid pressure becomes a low pressure corresponding to the pressure fluid filling resistance to the clutch cylinder 7, so the pressure fluid in the head chamber 14 of the cylinder 12 is Pressed by the springs 15 and 11, it passes through the check valve 16 and is discharged into the passage 17, and the set pressure of the relief valve 10 is reduced by the expanded spring 11. After filling the clutch cylinder 7 with pressure fluid,
The clutch 4 starts to engage as shown in FIG. 2, and since only a small amount of pressure fluid is needed, most of the pressure fluid from the pump 2 is passed through the relief valve 10 to the torque converter 19, cooler 20, and lubricating fluid. It is refluxed to the tank 9 via the distributor 21. Therefore, the supply liquid pressure becomes the pressure set by the relief valve 10, but at the same time, a part of the pressure liquid flows into the head chamber 14 through the throttle 18 and compresses the spring 11, so that the set pressure of the relief valve 10 gradually increases. do. As a result, the supply fluid pressure rises, and even after the clutch 4 is connected, it further rises, and when the head chamber 14 reaches its maximum capacity, the pressure in the head chamber 1 increases.
4 is stopped, and the relief valve 10 reaches its maximum setting pressure.

Note that 22 is a relief valve that limits the inflow pressure to the torque converter 19.

In the conventional device as described above, the pressure increase curve of the clutch cylinder hydraulic pressure from the completion of filling the clutch cylinder to the completion of clutch connection (hereinafter referred to as clutch connection time) is based on the hydraulic pressure circuit of this hydraulic pressure control device. It is uniquely determined from the structure, and if lined up, the pressure increase curve will be as shown by the one-dot chain line in FIG. However, the optimal boost curve is not always optimal because it differs depending on the clutch capacity of each speed stage, the difference in clutch upshift and downshift, and the difference in vehicle speed and rotational speed of the engine that drives the transmission. It becomes difficult to obtain a pressure increase curve, resulting in problems such as longer shift times and shocks being applied to the driver's vehicle during gear shifts.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic clutch cylinder control device that allows smooth and quick gear shifting operations using relatively inexpensive means.

In order to achieve the above-mentioned object, the cylinder hydraulic pressure control device according to the present invention provides a method for connecting a clutch between a pump and a directional control valve that selectively connects a plurality of clutch cylinders to a pump and a tank. an electric controller for calculating the pressure increase curve of the pump discharge pressure at a given time; an electromagnetic proportional relief valve whose set pressure is controlled by a command signal from the electric controller; and a proportional electromagnetic relief valve that reduces the set pressure of the electromagnetic proportional relief valve. A pressure control mechanism consisting of a pressure reduction mechanism and a train circuit for ensuring the pressure reduction function of this pressure reduction mechanism is provided.

The present invention will be explained below based on embodiments shown in the drawings. In FIG. 3, the directional control valve 3 selectively connects the clutch cylinders 7, 23, 8 of the hydraulic clutches 4, 5, 6 to the pump 2 and the tank 9, and a portion of the excess liquid is transferred to the pressure control valve. The fluid is returned from the mechanism 25 to the tank 9 via the torque converter 19, the cooler 20, and the lubricant distributor 21. The above configuration is the same as the conventional device shown in FIG.

In this embodiment, the pressure control mechanism 25 that controls the clutch cylinder hydraulic pressure includes an electric controller 26, an electromagnetic proportional relief valve 27 whose set pressure is controlled by a command signal from the electric controller, and an electromagnetic proportional relief valve 27 whose set pressure is controlled by a command signal from the electric controller. Directional switching valve 3 branched from the upstream flow path
In this embodiment, a drain passage 30 is provided with a spring-biased check valve 28 that allows fluid to flow only toward the directional control valve 3 side, and a fixed throttle 29 provided downstream of this check valve. It consists of

The electric controller 26 receives signals from sensors that detect the vehicle speed, the rotational speed of the engine that drives the transmission, the shift position of the directional control valve 3, etc., calculates the operating state of the vehicle, and calculates the operating state of the vehicle based on the operating state of the vehicle. A command signal is output to the electromagnetic proportional relief valve 27 so that the determined optimal pressure increase curve of the clutch cylinder hydraulic pressure when the clutch is engaged is obtained via the spring biased check valve 28.

The electromagnetic proportional relief valve 27 has a minimum pressure regulation pressure of 6.
Kg/cm ² or more, generally 6 to 8 Kg/cm ² is used. The reason for this is that regulating the pressure to a pressure of 6 kg/cm ² or less tends to cause unstable operation and delayed response, and a device that overcomes these problems would be quite expensive. However, in general, the fluid pressure supplied to the clutch cylinder needs to be gradually increased from 2 to 4 kg/ ^cm2 after filling with pressure fluid, and if the fluid pressure is high immediately after filling with pressure fluid, the shock at the start of clutch engagement may be large and smooth. Unable to shift gears. Therefore, in the present invention, a pressure reducing mechanism is attached to the electromagnetic proportional relief valve 27 to reduce the pressure to an appropriate clutch cylinder supply fluid pressure. This pressure reducing mechanism is a spring biased check valve 28 in this embodiment, but instead of this, for example, a throttle 31 and a constant differential pressure reducing valve 32 as shown in FIG.
You may also use

A drain circuit is provided downstream of the pressure reduction mechanism.
The reason for this is that the amount of pressurized fluid supplied to the clutch cylinder when the clutch is engaged is sufficient to prevent the pressure reducing function from being impaired due to the very small flow rate passing through the pressure reducing mechanism. In this embodiment, this drain circuit is a drain passage 30 provided with a throttle 29, but instead of this, for example, a flow rate regulating valve 33 with pressure compensation, an electromagnetic switching valve 35 equipped with a throttle 34, as shown in FIG. Pilot switching valve 3 with throttle 34
It may be 6. The electromagnetic switching valve 35 is opened only when the clutch is engaged in response to a command signal from the electric controller 26, and the pilot switching valve 36 is opened when the clutch is engaged because the hydraulic pressure supplied to the clutch cylinder is lowered. Since the electromagnetic switching valve 35 and the pilot switching valve 36 close due to pressure increase after the clutch is connected, excess fluid flows from the electromagnetic proportional relief valve 27 to the tank 9 via the torque converter 19, the cooler 20, and the lubricating fluid distributor 21, except during gear shifting operations. Reflux to.

In the configuration described above, for example, the clutch cylinders 7, 23 of the hydraulic clutches 4, 5 communicate with the tank 9, and the clutch cylinder 8 of the hydraulic clutch 6 communicates with the tank 9.
from the state in which the directional control valve 3 is in communication with the pump 2.
Clutch cylinder 7 of hydraulic clutch 4
If the clutch cylinder 8 of the hydraulic clutch 6 is connected to the tank 9, the hydraulic clutch 6 becomes clutch-off, and most of the pressure fluid from the pump 2 is transferred to the clutch cylinder 7, which has been empty. flows in, and the remaining pressurized liquid flows back to the tank 9 through the throttle 29 of the drain passage 30. When the clutch cylinder 7 is filled with pressure fluid, the electromagnetic proportional relief valve 27 is set to the lowest set pressure by the electric controller 26 which receives a gear change signal from the sensor that detects the shift position of the directional control valve 3. The pump fluid pressure, which is limited by the pump fluid pressure, is reduced as it passes through the spring-biased check valve 28, resulting in a low pressure corresponding to the pressure fluid filling resistance into the clutch cylinder 7. When the clutch cylinder 7 is filled with pressure fluid, the clutch is connected and the amount of pressure fluid supplied to the clutch cylinder 7 is very small, but a considerable amount of pressure fluid returns to the tank 9 through the throttle 29 of the drain passage 30. Therefore, the pressure reducing function of the spring biased check valve 28 is not impaired. The optimal pressure increase curve for the fluid pressure supplied to the clutch cylinder when the clutch is engaged is as shown in Figure 4, depending on the vehicle driving condition.
. . . The optimum pressure increase curve is determined by the electric controller 26 from the operating conditions, and the electric controller 26 operates so that this optimum pressure increase curve is realized via the spring-biased check valve 28. Then, the set pressure of the electromagnetic proportional relief valve 27 is controlled to be as high as the pressure reduced by the spring-biased check valve 28, thereby ensuring an optimum clutch cylinder hydraulic pressure when the clutch is engaged, thereby obtaining proper clutch engagement.

When the clutch connection is completed, the pump hydraulic pressure is increased to the maximum setting pressure of the electromagnetic proportional relief valve 27 to maintain the clutch connection state. In this case, if the flow rate adjustment valve in the drain passage 30 is an electromagnetic switching valve 35 or a pilot switching valve 36, the valve is closed by a command from the electric controller 26 or pilot pressure, and all excess liquid is drained from the electromagnetic proportional relief valve 27 to the torque converter 19, It flows back to the tank 7 via the cooler 20 and the lubricant distributor 21. The flow rate regulating valve is the throttle 29 and the pressure compensated flow regulating valve 33 is divided into a drain passage 30 and an electromagnetic proportional relief valve 27, and the flow is returned to the tank 9.

In this embodiment, the timing of hydraulic control during pressure fluid filling is calculated by an electric controller that receives a gear shift signal from a sensor that detects the shift position of the directional valve 3. For example, when a device such as an electromagnetic switching valve that is operated by an electric command signal is used, the electric command signal may be received by an electric controller instead of the signal from the sensor.

As explained above, in the present invention, the optimal pressure increase curve of the clutch cylinder hydraulic pressure when the clutch is engaged is determined by the electric controller from the vehicle operating state, and the electromagnetic proportional relief valve is controlled by the command signal from the electric controller. Since the pump fluid pressure, which is controlled by the electromagnetic proportional relief valve, is obtained by reducing the pressure using the pressure reducing mechanism, it is possible to perform gear shifting operations smoothly and quickly. Therefore, the cost of the pressure control mechanism can be reduced.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of a conventional device, FIG. 2 is a chart showing pressure changes of pump hydraulic pressure and clutch cylinder hydraulic pressure in a conventional device, and FIG. 3 is a hydraulic circuit diagram showing an embodiment of the present invention. FIG. 4 is a chart showing the increased state of the clutch cylinder hydraulic pressure when the clutch is connected in the device of the present invention, and FIG. 5 is a diagram of an example of a pressure reducing mechanism and a drain circuit used in the device of the present invention. 2... Pump, 3... Directional switching valve, 4, 5, 6
... Hydraulic clutch, 7, 8, 23 ... Clutch cylinder, 25 ... Pressure control mechanism, 26 ... Electric controller, 27 ... Electromagnetic proportional relief valve, 28 ... Spring biased check valve, 29, 31, 34...
... Throttle, 32 ... Constant difference pressure reducing valve, 33 ... Flow rate adjustment valve with pressure compensation, 35 ... Solenoid switching valve, 36 ... Pilot switching valve.

Claims (1)

[Claims] 1. An electric controller between the pump and the directional control valve that selectively connects the plurality of clutch cylinders to the pump and the tank, for calculating a pressure increase curve of the pump discharge pressure when the clutch is engaged based on the vehicle operating state; From an electromagnetic proportional relief valve whose set pressure is controlled by a command signal from this electric controller, a pressure reducing mechanism that reduces the set pressure of this electromagnetic proportional relief valve, and a drain circuit to ensure the pressure reducing function of this pressure reducing mechanism. A hydraulic clutch cylinder control device characterized by being equipped with a pressure control mechanism.