JPH059274Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a control device for a variable displacement hydraulic pump.

Prior Art In a conventional variable displacement hydraulic pump control device, the absorption torque of the main pump is set in advance to be low by the absorption torque of the steering pump.

Problems that the invention aims to solve: For this reason, the driving performance was poor compared to the engine performance.

The present invention was developed in view of the above circumstances, and its purpose is to detect the discharge pressure of the steering pump and use that pressure to control the absorption torque of the main pump, thereby achieving high output performance with an engine of the same performance. It's about getting.

Means and Effects for Solving the Problems The present invention provides a servo piston section 6 having a servo piston 31 that controls the discharge amount of the variable displacement main pumps 1 and 2, and a servo piston section 6 having a servo piston 31 that controls the discharge amount of the variable displacement main pumps 1 and 2. The hydraulic fluid from the first switching port and the pilot pump 3 is intermittently applied to the pressure chamber 44 on the side where the discharge amount is increased in the servo piston portion 6 and is intermittently applied to the pressure chamber 46 on the side where the discharge amount is decreased in the servo piston portion 6. a second switching port, and the first switching port is in communication during straight-ahead operation, and the guide valve is operated by hydraulic pressure from the steering pump 4 during steering operation. The control valve part 7 is configured to switch and control the control valve part 7 to communicate with the second switching port, and the control valve part 7 is actuated by the discharge pressure of the steering pump 4 to open the guide valve. By switching the section 8, the discharge pressure from the pilot pump 3 is applied to the pressure chamber 46 of the servo piston section 5, thereby operating the servo piston 31 in the direction of decreasing the discharge amount.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are variable capacity main pumps, 3 is a pilot pump, 4 is a steering pump, and 5 is a servo valve structure.

The servo valve assembly 5 includes a servo piston section 6, a control valve section 7, and a guide valve section 8.

The control valve part 7 has a sleeve 1 inserted into the valve body 9.
0, and the sleeve 10 has ports 11,
12, 13, 14, 15, 16 are provided, and pistons 17, 18, 19, 2 are provided in the sleeve 10.
0, 21, and 22 are inserted. Also, the control valve section 7
is equipped with a spool 23, a spring receiver 24 is provided at one end of the spool 23, and a spring 26 is interposed between the spring receiver 25 fitted to the valve body 9 and the spring receiver 24. There is. Further, a pressure regulating bolt 27 is screwed into the spring receiver 25, a pressure regulating spring 28 is interposed between the pressure regulating bolt 27 and the spring receiver 24, and the other end of the spool 23 is connected to a piston. It is in contact with 17. The lever 29 is attached to the pin 3 on the spool 23.
0, and one end of the lever 29 is connected to the servo piston 31 of the servo piston section 6.
It is rotatably locked to.

The guide valve portion 8 includes a sleeve 33 fitted into the fitting hole 32 of the valve body 9.
The sleeve 33 is provided with an input port 35, and a first switching port 36 and a second switching port 34 located on both sides of the input port 35.
A spool 37 is fitted into the spool 37, and this spool 37 is held in a neutral position by a spring 38. In this state, the input port 35 and the first switching port 36 are communicated with each other, and the spool 37 is moved to one side. In this state, the input port 35 is switched to the second switching port 3.
It is now connected to 4. Furthermore, the other end of the lever 29 is rotatably secured to the spool 37.

The discharge side of the main pump 1 is connected to the port 12 of the control valve section 7 via a conduit 39, and the discharge side of the main pump 2 is connected to the port 14 via a conduit 40. The side is connected via a line 41 to the port 16 of the control valve part 7. The discharge side of the pilot pump 3 is the pipe line 4.
2 to the input port 35 of the guide valve section 8, and the first switching port 35 of the guide valve section 8 is connected to the pressure chamber 44 of the servo piston section 6 via a conduit 43.
Furthermore, the second switching ports 34 are connected to pressure chambers 46 via conduits 45, respectively.

Further, ports 11, 13, and 15 of the control valve section 8 are connected to the drain side.

Therefore, when the vehicle is traveling straight, the hydraulic oil discharged from the pilot pump 3 flows through the pipe 42, the input port 35 of the guide valve section 8, and the first
It acts on the pressure chamber 44 of the servo piston section 6 through the switching port 36 and the conduit 43, pushes the servo piston 31, and the discharge amount Q is maximized.

Steering pump 4 during steering operation
The discharge amount increases and this hydraulic oil pushes the piston 21 of the control valve section 7 to the left, so the spool 23 is pushed to the left, and the spool 37 of the guide valve section 8 moves to the left via the lever 29. The input port 35 and the second switching port 34 communicate with each other, and the hydraulic oil from the pilot pump 3 acts on the pressure chamber 46 of the servo piston section 6, pushing the servo piston 31 leftward and switching the main pump 1 off. , 2 will decrease.

This servo characteristic is shown in FIG. As you can see from this servo characteristic, the steering load pressure is 32Kg/
Pump torque decreases when increasing from ^cm2 to 131Kg/ ^cm2 .

Effects of the Invention Since the present invention is as described above, the control valve section 7 is actuated by the discharge pressure of the steering pump 4 to switch the guide valve section 8 to transfer the discharge pressure from the pilot pump 3 to the servo piston section 6. By acting on the pressure chamber 46, the servo piston can be operated in the direction of reducing the discharge amount.

In this way, the discharge pressure of the steering pump 4 is detected, and the absorption torque of the main pumps 1 and 2 is controlled using the detected pressure, so that high output performance can be obtained with an engine of the same performance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the same operation, and FIG. 3 is an explanatory diagram of servo characteristics. 1 and 2 are main pumps, 3 is a pilot pump, 6 is a servo piston section, 7 is a control valve section, and 8 is a guide valve section.

Claims (1)

[Scope of utility model registration request] The servo piston section 6 has a servo piston 31 that controls the discharge amount of the variable displacement main pumps 1 and 2, and the hydraulic oil from the pilot pump 3 can be intermittently connected to the pressure chamber 44 on the side of the servo piston section 6 that increases the discharge amount. and a second switching port that allows the hydraulic oil from the pilot pump 3 to act intermittently on the pressure chamber 46 on the discharge volume reduction side of the servo piston section 6. The guide valve section 8 is in communication with the first switching port, and the second switching port is operated by hydraulic pressure from the steering pump 4 during steering operation to communicate with the guide valve section 8. 1. A control device for a variable displacement hydraulic pump, comprising: a control valve section 7 for switching control.