JPH0617917A - Hydraulic control unit of vehicle transmission - Google Patents

Abstract

PURPOSE:To enhance the accuracy of control of line pressure when a duty solenoid valve is used to control the line pressure. CONSTITUTION:The hydraulic pressure of a line pressure oil passage 16 is controlled by a regulator valve 18. The regulator valve 18 has two signal ports 18d, 18e. While the pressure is regulated to a low state, a duty solenoid pressure acts on the signal port 18d. While the pressure is regulated to a high state, the duty solenoid pressure acts on the signal port 18e. When the duty ratio is increased from 0 to 100% as the pressure is regulated to the low state, the line pressure changes from a minimum value P1 to an intermediate value P0. Next the duty ratio is changed from 100 to 0% by switching of a hydraulic pressure setting switching valve 24 and then the line pressure is changed from the intermediate value P0 to P2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for a vehicle transmission.

[0002]

2. Description of the Related Art In a transmission such as an automatic transmission or a continuously variable transmission, it is necessary to control the hydraulic pressure of a line pressure, which is a hydraulic pressure source oil passage, according to the throttle opening, the vehicle speed and the like. A technique for electronically controlling the line pressure using a duty solenoid is disclosed in, for example, Japanese Patent Laid-Open No. 62-62047. The line pressure control device shown therein is a line pressure solenoid,
It has a pilot valve, a pressure modifier valve and a pressure regulator valve, and the constant pressure obtained by the pilot valve is used as a hydraulic pressure source to adjust the throttle pressure by a line pressure solenoid, and this is further adjusted by a pressure modifier valve, The oil pressure obtained by this is made to act on the pressure regulator valve as a signal pressure. The pressure regulator valve regulates the line pressure according to the signal pressure. Therefore, the line pressure is controlled according to the hydraulic pressure obtained by the line pressure solenoid. The line pressure solenoid is of a type in which the duty ratio is controlled, and by repeatedly turning on and off at a constant cycle, the orifice is opened and closed to adjust the throttle pressure. By changing the on / off ratio of the line pressure solenoid, it is possible to change the drain amount from the orifice and adjust the hydraulic pressure as desired.

[0003]

However, in the above-mentioned conventional line pressure control device, when the width between the minimum value and the maximum value of the line pressure becomes large, the control accuracy of the hydraulic pressure is lowered and the pulsation of the hydraulic pressure is decreased. There is a problem that is increased.
That is, the line pressure corresponds to the duty ratio given to the line pressure solenoid. For example, if the width of the line pressure is doubled from the conventional one, the line pressure is doubled for the same duty ratio fluctuation. It will fluctuate. In the V-belt type continuously variable transmission in which the required line pressure greatly changes in accordance with the input torque and the gear ratio as compared with the stepped automatic transmission, the above range of the line pressure becomes large, so that the control accuracy of the hydraulic pressure is a problem. Becomes In this case, it is possible to set the line pressure high considering the safety factor so that the minimum required hydraulic pressure is guaranteed even if the hydraulic pressure changes.
In this case, the line pressure becomes unnecessarily high, the load on the oil pump increases, the transmission efficiency of the V-belt type continuously variable transmission mechanism decreases, and the efficiency of the entire transmission decreases. Further, as described above, the line pressure solenoid is repeatedly turned on and off at a constant cycle, and the line pressure also pulsates in response to this, but this pulsation is also large in proportion to the width of the line pressure. Become. When the pulsation of the hydraulic pressure increases, abnormal noise may be generated or the strength of the member on which the hydraulic pressure acts needs to be improved. The present invention aims to solve such problems.

[0004]

According to the present invention, by switching between a low pressure regulation state and a high pressure regulation state, the duty ratio of the duty solenoid is minimized in the range between the minimum value and the maximum value of the line pressure. The above problem is solved by associating the width between the value and the maximum value twice. That is, a hydraulic control device for a vehicle transmission according to the present invention includes an oil pump that sucks oil in a reservoir and discharges the oil into a line pressure oil passage, and a regulator valve that regulates the oil pressure in the line pressure oil passage. An electronic control unit, a duty solenoid valve that outputs a duty solenoid pressure according to a duty ratio given from the electronic control unit, and a hydraulic setting switching valve that is switched on / off by a signal from the electronic control unit,
The hydraulic pressure setting switching valve operates the duty solenoid pressure or other predetermined hydraulic pressure on the signal port of the regulator valve in either one of the high pressure regulating state and the low pressure regulating state. The regulator valve is switchable, and the maximum value of the line pressure regulated according to the duty solenoid pressure in the low pressure regulation state and the minimum value of the line pressure regulated according to the duty solenoid pressure in the high pressure regulation state are equal. Is configured to be.

[0005]

[Operation] When the oil pressure setting switching valve is in the low pressure regulating state,
When the duty ratio changes from the minimum value to the maximum value, the line pressure increases from the minimum value to a predetermined intermediate value. Next, when the oil pressure setting switching valve is switched to the high pressure regulating state, the line pressure changes from the intermediate value to the maximum value according to the change between the minimum value and the maximum value of the duty ratio. The line pressure changes from the minimum value to the maximum value while the duty value changes twice between the minimum value and the maximum value. Therefore, the control accuracy is doubled. Also, the pulsation of hydraulic pressure is reduced to 1/2.

[0006]

1 to 3 show a first embodiment. As shown in FIG. 1, the oil pump 10 sucks the oil in the reservoir 12 through the strainer 14 and discharges it to the line pressure oil passage 16. The line pressure oil passage 16 is provided with a regulator valve 18 which regulates the hydraulic pressure of the line pressure oil passage 16. Regulator valve 18
Discharges the required amount of oil from the input port 18a connected to the line pressure oil passage 16 from the discharge port 18b to perform the pressure adjusting action. The hydraulic pressure of the input port 18a is guided to the feedback port 18c, and a spring 18f is provided so as to oppose the force of the hydraulic pressure acting on the feedback port 18c. The regulator valve 18 is further provided with signal ports 18d and 18e. Signal port 18d and signal port 18e
Are arranged so as to exert mutually opposite forces on the regulator valve 18. The signal port 18d is connected to the oil passage 20 and the signal port 18e is connected to the oil passage 22. The supply state of the hydraulic pressure to the oil passages 20 and 22 is controlled by the hydraulic pressure setting switching valve 24. Hydraulic setting switching valve 2
4 is capable of switching between the low pressure regulating state shown in FIG. 1 and the high pressure regulating state in which this is switched in the opposite direction according to the hydraulic pressure acting from the oil passage 26 to the port 24a. In the low pressure regulating state, the oil passage 28 is connected to the oil passage 20 and the oil passage is connected so as to drain the oil passage 22. Further, in the high pressure regulating state, the oil passage 28 is connected to the oil passage 22 and the oil passage 20 is drained. The oil pressure in the oil passage 26 is controlled by the on / off solenoid valve 30. In addition, the oil passage 28
The hydraulic pressure (duty solenoid pressure) is controlled by the duty solenoid valve 32. The operations of the on / off solenoid valve 30 and the duty solenoid valve 32 are controlled by electric signals from the electronic control unit 34.

Next, the operation of this embodiment will be described. The electronic control unit 34 determines the line pressure to be set based on the current operating conditions such as the gear ratio, the vehicle speed and the engine load. When the determined line pressure is lower than the predetermined value P0 (see FIG. 3) (that is, the low pressure regulating state), a signal is output to the on / off solenoid valve 30 to drive it and set the hydraulic pressure. The switching valve 24 is brought into the state shown in FIG.
Further, the electronic control unit 34 sets the duty ratio DX corresponding to the line pressure PX to be set to the duty solenoid valve 32.
Output to. As a result, the duty solenoid valve 3
2 outputs the duty solenoid pressure corresponding to the duty ratio DX to the oil passage 28. The relationship between the duty ratio and the duty solenoid pressure is as shown in FIG. The duty solenoid pressure output to the oil passage 28 is supplied to the oil passage 20 via the hydraulic pressure setting switching valve 24,
It acts on the signal port 18d of the regulator valve 18. On the other hand, hydraulic pressure does not act on the signal port 18e of the regulator valve 18. As a result, the regulator valve 18 performs a pressure adjusting action so that the hydraulic pressure in the line pressure oil passage 16 becomes PX.
When the duty ratio applied to the duty solenoid valve 32 is changed from 0% to 100% in this state, the line pressure changes from P1 to P0 as shown in FIG. Next, when the line pressure commanded by the electronic control unit 34 becomes PY higher than P0, the on / off solenoid valve 3
0 switches the oil pressure setting switching valve 24 to a state opposite to the state shown in FIG. Further, the duty solenoid valve 32 is provided with a predetermined duty ratio DY. Accordingly, the duty solenoid pressure corresponding to the duty ratio DY is
It acts on the signal port 18 e via the oil passage 28, the oil pressure setting switching valve 24 and the oil passage 22. On the other hand, the signal port 18d is drained. In this state, the line pressure oil passage 16 is balanced by the balance between the force generated by the hydraulic pressure acting on the feedback port 18c and the force generated by the spring 18f and the duty solenoid pressure acting on the signal port 18e.
The hydraulic pressure of is determined. In this state, the duty ratio is 100
When changing from 0% to 0%, the line pressure changes from P0 to P2 as shown in FIG.

After all, by the above control, the duty ratio becomes 0.
The line pressure characteristic as shown in FIG. Line pressure minimum P1 to maximum P2
To change the duty ratio from 0% to 100%,
Further, it changes from 100% to 0%, and the change rate of the line pressure with respect to the change of the duty ratio becomes small. That is, the control accuracy is improved. Compared to the case where the line pressure is controlled only from 0% to 100% duty ratio from P1 to P2, the control accuracy is about twice (in the example shown in FIG. 3, the line pressures P1 to P0 The accuracy is more than double, and the line pressures P0 to P2 are slightly less than double accuracy. Further, the pulsation of the line pressure generated by the ON / OFF operation of the duty solenoid valve 32 is also reduced to about 1/2. It should be noted that, as in the first embodiment, the control accuracy in the low pressure regulating state is made higher (this can be realized by making the pressure receiving area of the signal port 18d smaller than the pressure receiving area of the signal port 18e). The safety factor on the low-pressure side of the line pressure can be set smaller, and the line pressure can be set lower by that amount, so that the efficiency of the transmission is improved.

Next, a second embodiment shown in FIGS. 4 and 5 will be described. The second embodiment shown in FIG. 4 is different from the first embodiment in the hydraulic connection state of the duty solenoid valve 32 and the hydraulic pressure setting changeover valve 24, and other configurations are basically the same as those shown in FIG. This is the same as in the first embodiment. That is,
The duty solenoid pressure of the duty solenoid valve 32 is always the signal port 18d (first port) of the regulator valve 18.
Signal port). Further, the oil pressure setting switching valve 24 supplies the oil pressure of the oil passage 40, which is always supplied with a constant oil pressure, to the signal port 18e (second port) of the regulator valve 18.
It is configured to switch between acting on the signal port) and draining the port 18e. In the second embodiment, when the line pressure PX commanded by the electronic control unit 34 is smaller than P0 (low pressure adjusting state),
The line pressure characteristics are similar to those of the first embodiment. On the other hand, when the commanded line pressure PY is larger than P0 (high pressure regulating state), the hydraulic pressure setting switching valve 24 is switched to the state shown in FIG. 4, and a constant hydraulic pressure is applied to the signal port 18e of the regulator valve 18. Because of the action, the line pressure becomes higher than that in the low pressure regulated state, and the line pressure characteristic increases as the duty ratio increases, as shown in FIG. Even in this case, the line pressure can be changed from P1 to P2 by changing the duty ratio from 0% to 100%, then rapidly returning to 0%, and increasing again to 100%. It is possible to double the control accuracy of 1 and reduce the pulsation of hydraulic pressure to 1/2. In each of the above embodiments, when the hydraulic pressure setting switching valve 24 is switched by the signal from the electronic control unit 34,
Although the configuration is performed indirectly using the on / off solenoid valve 30, the present invention is not limited to these. The hydraulic pressure setting switching valve 34 may be a direct-acting valve, and may be directly switched by a signal from the electronic control unit 34 without passing through the on / off solenoid valve 30.

[0010]

As described above, according to the present invention, the degree of change of the line pressure with respect to the change of the duty ratio is set to about 1/2, the control accuracy is improved to about double, and the pulsation of hydraulic pressure is set to about 1. It can be / 2.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a duty ratio and a duty solenoid pressure.

FIG. 3 is a diagram showing a relationship between a duty ratio and a line pressure.

FIG. 4 is a diagram showing a second embodiment of the present invention.

FIG. 5 is a diagram showing a relationship of a line pressure with respect to a duty ratio in the second embodiment.

[Explanation of symbols]

 10 Oil Pump 12 Reservoir 16 Line Pressure Oil Path 18 Regulator Valve 24 Set Hydraulic Pressure Switching Valve 30 On / Off Solenoid Valve 32 Duty Solenoid Valve 34 Electronic Control Device

Claims (3)

[Claims] 1. An oil pump that sucks oil in a reservoir and discharges it to a line pressure oil passage, a regulator valve that regulates the hydraulic pressure of the line pressure oil passage, an electronic control unit, and an electronic control unit. It has a duty solenoid valve that outputs a duty solenoid pressure according to a given duty ratio, and a hydraulic setting switching valve that is switched on / off by a signal from an electronic control unit. The solenoid valve or other predetermined hydraulic pressure can be switched so that it acts on the signal port of the regulator valve in either one of the high pressure regulating state and the low pressure regulating state. The maximum value of the line pressure that is adjusted according to the duty solenoid pressure in the state, and the line pressure that is adjusted according to the duty solenoid pressure in the high pressure adjustment state A hydraulic control device for a vehicle transmission, which is configured so that the minimum value of the line pressure is equal. 2. The hydraulic pressure setting switching valve is configured to switch the duty solenoid pressure to a signal port in which the operating directions of the regulator valve are opposite to each other in the low pressure regulating state and the high pressure regulating state. Item 2. A hydraulic control device for a vehicle transmission according to Item 1. 3. The duty solenoid pressure is constantly supplied to the first signal port of the regulator valve, and the hydraulic pressure setting switching valve keeps a constant hydraulic pressure in the second signal port of the regulator valve in the low pressure regulating state and the high pressure regulating state. 2. A structure configured to switch between a state in which it acts on and a state in which it does not act.
A hydraulic control device for a vehicle transmission described.