JPH031515B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a vane type variable displacement pump.

As a conventional control device for a vane type variable displacement pump, there is one shown in FIG. 1, for example. A cam ring 1 of the vane type pump is swingable about a pin 2, and a rotor 4 is provided with a vane 3 that is movable in the radial direction on the inner diameter of the cam ring 1.
is provided. Lever 1a integrated with cam ring 1
The force from the spring 5 and the hydraulic cylinder 6 are
The force exerted by the piston rod 6a acts in opposite directions to each other, and the amount of eccentricity of the cam ring 1 is determined by the combination of both forces. The rotor 4 rotates clockwise in FIG. 1, sucks oil from the tank 7 through the oil passage 8 into the suction port 1b, and discharges pressure oil from the discharge port 1c into the oil passage 9. The pressure oil in the oil passage 9 is regulated to a predetermined pressure (line pressure) by a control valve 10, and is supplied to hydraulic equipment such as a clutch (not shown). The oil passage 9 is also led to a regulator valve 11, and when the line pressure of the oil passage 9 is higher than the set pressure, the regulator valve 11 supplies the line pressure to the hydraulic cylinder 6 via the oil passage 12. When the line pressure is lower than the set pressure, the oil in the hydraulic cylinder 6 is discharged to the tank 7. With this configuration, when the rotation speed of the rotor 4 is low, oil pressure is not supplied to the hydraulic cylinder 6 and the amount of eccentricity increases, and when the rotation speed of the rotor 4 is high, line pressure is supplied to the hydraulic cylinder 6. is supplied, resulting in the effect of reducing the amount of eccentricity. By doing so, it is possible to ensure the discharge amount during low speed rotation and reduce energy loss during high speed rotation.

However, the conventional vane type variable displacement pump control device as described above uses a hydraulic cylinder to control the eccentricity of the cam ring, which requires many parts and is expensive. Another problem was that it required a large amount of space.

The present invention has been made by focusing on the above problems in conventional vane type variable displacement pump control devices, and it is an object of the present invention to enable communication between the discharge side confinement part and the suction side confinement part of the pump. According to
The purpose is to solve the above problems.

Hereinafter, the present invention will be explained based on FIG. 2 of the accompanying drawings showing an embodiment thereof.

First, the configuration will be explained.

The cam ring 21 is swingable about a pin 22, and the rotor 2 is provided with a vane 23 that is movable in the radial direction on the inner diameter of the cam ring 21.
4 is provided. A force from a spring 25 acts on a lever 21a that is integral with the cam ring 21 so as to rotate the cam ring 21 clockwise. The rotor 24 rotates clockwise in FIG. 2, sucks oil from the tank 27 through the oil passage 28 into the suction port 21b, and discharges pressure oil from the discharge port 21c into the oil passage 29. Oil road 2
The pressure oil 9 is regulated to a predetermined pressure (line pressure) by a control valve 30, and is supplied to hydraulic equipment such as a clutch (not shown). Oil road 29
The line pressure is led to the regulator valve 31 as pilot pressure. Regulator valve 3
1, an oil passage 33 communicating with the discharge side confinement part 32 of the pump and an oil passage 34 communicating with the suction side confinement part 35 of the pump are led, and the line pressure as the pilot pressure is set. When the line pressure is higher than the set pressure, both oil lines 33 and 34 are cut off, and when the line pressure is less than the set pressure, both oil lines 33 and 34 are cut off.
are designed to communicate.

Next, the effect will be explained.

When the rotor 24 rotates clockwise in FIG. 2, the oil in the tank 27 is sucked into the suction port 21b through the oil passage 28, and is discharged into the oil passage 29 from the discharge port 21c. In addition, at that time, the vane 23
There are two locations (on the suction side and the discharge side) where oil is trapped between the two. That is, the second
These are the suction side confinement part 35 on the upper side in the figure and the discharge side confinement part 32 on the lower side. As mentioned above, the discharge side confinement part 32 and the suction side confinement part 35 are connected to the regulator valve 31 by oil passages 33 and 34, respectively. By the way, the discharge side confinement part 32 confines the discharge pressure (line pressure) of the discharge port 21c as it is, so the pressure of the discharge side confinement part 32 is almost equal to the line pressure, and the suction side confinement part 35 has a negative pressure. status suction port 21b
Since the suction side confining portion 35 is confined from the inside, the pressure in the suction side confining portion 35 is approximately zero. In the vane type variable displacement pump control device according to the present invention, the eccentricity of the cam ring 21 is controlled as follows by utilizing the pressure difference between the two confining portions 32 and 35. When the rotational speed of the rotor 24 is low and the line pressure does not reach the set pressure of the regulator valve 31, the regulator valve 31 connects the oil passage 33 and the oil passage 34, so that the discharge side confinement portion 32 oil pressure is introduced into the suction side confinement part 35, and the oil pressures of the discharge side confinement part 32 and the suction side confinement part 35 are both approximately equal to the line. Therefore, no hydraulic force acts on the cam ring 21 at all. Therefore, the cam ring 21 is pushed to the maximum eccentric position by the force of the spring 25, and the discharge volume is increased.
When the rotation of the rotor 24 becomes faster and the discharge amount increases and the line pressure exceeds the set pressure of the regulator valve 31, the regulator valve 31 is switched and the communication between the oil passages 33 and 34 is cut off. Since the oil in the discharge side confinement part 32 is no longer supplied to the suction side confinement part 35, the oil pressure in the suction side confinement part 35 becomes almost zero. Since a hydraulic pressure approximately equal to the line pressure is applied to the discharge side confinement portion 32, a force is applied to the cam ring 21 to rotate it counterclockwise in FIG. 2. Therefore, the amount of eccentricity of the cam ring 21 decreases, and the discharge volume decreases. The higher the line pressure is, the more the pressure increases from the discharge side confinement part 32 to the cam ring 2.
1 becomes larger, and conversely, as this force becomes larger, the amount of eccentricity becomes smaller and the discharge amount decreases. Therefore, the cam ring 21 is balanced at a predetermined position, and the oil in the control valve 30, each oil passage, clutch, etc. Supply the minimum amount of oil required by the entire hydraulic circuit, such as leakage.

In addition, in the above embodiment, the regulator valve 3
The set pressure in No. 1 is set as a constant pressure by a spring, but if you want to temporarily increase the discharge amount depending on the operating condition of the equipment that uses this pump, for example, you can apply a predetermined oil pressure to the regulator valve 31. There is no problem in changing the set pressure by applying the pressure.

As described above, according to the present invention, the oil passage communicating with the discharge side confinement part of the pump and the oil passage communicating with the suction side confinement part of the pump are guided to the regulator valve. is provided with a first switching position for communicating the two oil passages with each other and a second switching position for cutting off the communication between the two oil passages,
The pump discharge pressure is guided as pilot pressure to this regulator valve, and when the pump discharge pressure is below the set pressure, the regulator valve is in the first switching position, and when the pump discharge pressure is higher than the set pressure, the regulator valve is set to the first switching position. The regulator valve is set to the second switching position, and a spring is installed that constantly applies a force that swings the cam ring in the direction that increases the amount of eccentricity, so there is no need for a hydraulic cylinder to swing the cam ring. Therefore, it is possible to reduce the cost and to downsize the pump control device.

Furthermore, the present applicant achieved the same object as above by discharging the oil in the discharge-side confinement section in a predetermined case in Japanese Patent Application No. 191861/1986 entitled "Control Device for Vane Type Variable Displacement Pump." However, when comparing the invention described in Japanese Patent Application No. 56-191861 with the present invention, it is found that the present invention utilizes the hydraulic pressure of the high-pressure discharge side confinement portion as it is without discharging it. This control has the advantage that volumetric efficiency does not decrease.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional vane type variable displacement pump control device, and FIG. 2 is a diagram showing a vane type variable displacement pump control device according to the present invention. 21...cam ring, 21b...intake port,
21c...Discharge port, 22...Pin, 23...
Vane, 24...rotor, 25...spring,
27...tank, 28...oil line, 29...oil line,
30...Control valve, 31...Regulator valve, 32...Discharge side confinement part, 33...
...Oil passage, 34...Oil passage, 35...Suction side confinement part.

Claims (1)

[Scope of Claims] 1. A control device for a vane-type variable displacement pump in which the discharge amount is varied by adjusting the amount of eccentricity of a cam ring, which is swingably disposed in the inner diameter of the housing, from the center axis of the inner diameter of the housing, An oil passage communicating with the discharge side confinement part of the pump and an oil passage communicating with the suction side confinement part of the pump are led to a regulator valve, and the regulator valve has a first switching switch that allows the two oil passages to communicate with each other. A position and a second switching position are provided to cut off communication between the two oil passages, and the pump discharge pressure is guided as pilot pressure to this regulator valve, and when the pump discharge pressure is less than the set pressure, the regulator valve is switched off. The regulator valve is set to the first switching position, and when the pump discharge pressure is higher than the set pressure, the regulator valve is set to the second switching position, so that the force that swings the cam ring in the direction that increases the amount of eccentricity is always applied. A control device for a vane type variable displacement pump, characterized in that it is provided with a spring to act.