JPS6011281Y2 - Hydraulic pump capacity control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cut-off control of a variable displacement hydraulic pump, that is, a control device that prevents overpressure by reducing pump capacity in order to reduce energy loss due to a relief valve.

Conventionally, when operating a plurality of actuators with the same variable displacement hydraulic pump, it has been necessary to change the cutoff setting value of the variable displacement hydraulic pump for each actuator.

The present invention was developed in view of the above circumstances, and its purpose is to automatically change the cutoff setting value of the cutoff control device of a variable displacement hydraulic pump depending on the type of actuator. There is a particular thing.

Hereinafter, the present invention will be explained with reference to the drawings.

Figures 1 and 2 show switching valves, 3 is an actuator that is operated by operating the switching valve 1, and 4 is an actuator that is operated by operating the switching valve 2.

Ports la and 2a of the switching valve 1.2 are connected to the discharge side of the variable displacement pump 5 via check valves 6 and 7, and a shuttle valve is connected between the pipes A and 8 leading from the switching valve 1 to the actuator 3. 8 is a provision.

9 in the drawing is a servo booster that controls the capacity of the variable displacement pump 5; 10. is a servo pilot spool valve,
11 is a cut-off control valve.

The discharge side of charge pump 12 communicates with tank 14 via relief valve 13, and the discharge side of charge pump 12 communicates with the large end of servo booster 9 via servo pilot spool 10.

The cut-off control valve 11 is provided with a valve block 15 as shown in FIG. , the output port 19 communicates with the output port 18 via a feedback circuit 20.

A plug body 22 is provided at one end of the spool hole 21 of the valve block 15, and a pump port 24 is provided in the plug body 22.

Sleeves 25, 26, and 27 are fitted into the spool hole 21, and the sleeve 26 is provided with a guide hole 26a communicating with the pressure port 17.

A cylindrical body 28 is fixed to the end of the valve block 15.

A pin 29 is slidably provided in the sleeve 25, a pin 30 is provided in the sleeve 26, and a spool 31 is slidably provided in the sleeve 27, and a spring receiver 32 is fitted into the end of the spool 31. .

A piston-shaped stopper 33 is movably provided within the cylindrical body 28, and an adjustment screw 34 that abuts against the stopper 33 is provided on the cylindrical body 28.

A spring 35 is inserted between the spring receiver 32 and the stopper 33.
is an intermediary.

The sleeve 27 is provided with ports 36', 37', and 38, and the spool 31 is provided with a through hole 39.

The pump port 24 communicates with the discharge side of the variable displacement pump 5, and the pump port 16 communicates with the discharge side of the charge pump 12.

Further, the pressure port 17 communicates with the shuttle valve 8, and the output port 18 communicates with the operating port 10a of the servo pilot spool valve 10 via a throttle 40.

Further, the discharge side of the charge pump 12 directly communicates with the large end of the servo booster 9.

Next, the operation will be explained.

The variable displacement pump 5 operates the actuators 3 and 4 in a parallel circuit.

In the switching valve 1, the piping A of the neutral actuator 3,
Connected to B hadrain.

In the switching valve 2, both pipes A and B are closed when in neutral.

The maximum operating pressure P1* of actuator 3 is lower than the maximum operating pressure P2* of actuator 4 (pt*<42)
.

When the switching valve 1 is in the neutral position, the capacity of the variable displacement pump 5 is cut-off controlled by detecting the pump discharge pressure Pp.

At this time, Pp=P2*When the switching valve 1 is switched upward or downward, the load pressure P1 of the actuator 3 is detected through the shuttle valve 8, and cut-off control is performed.

At this time Pp=P1*〈P2* The characteristics of the cutoff control valve 11 are shown in FIG.

Pp is the pump discharge pressure, P is the operating pressure of the actuator 3, and Pi is the cutoff control valve output pressure.

When the pump discharge pressure Pp is low, the spool 31 is pushed left and right by the spring 35, the pump port 16 and the output port 18 are communicated, and the space between the output port 18 and the drain port 23 is closed.

Therefore, the output pressure Pi of the output port 18 is
It is equal to the charge pressure Ps of 6.

Operating pressure P of actuator 3 guided to pressure port 17
1 is zero, the pump discharge pressure Pp increases, and when the P2 tree is reached, the spool 31 moves to the right against the spring 35 via the pins 29, 30.

As a result, the space between the whip (t-knee) 16 and the output port 18 is closed, the output port 18 and the drain port 23 are communicated with each other, and the output pressure Pi is reduced.

The P2 tree is defined by the outer diameter of pin 29 and the spring force set by adjustment screw 34.

When the actuator 3 is actuated and P□=Pp, when the pump discharge pressure Pp reaches P□*, the spool 31 moves to the right via the pin 30, and in the same manner as the above-mentioned operating principle, Pi becomes descend.

P1* is determined by the outer diameter of the pin 30, and if the outer diameter of the pin 30 is made larger than the outer diameter of the pin 29, P1*<P2*.

The outer diameter of the spool 31 is larger than the outer diameter of the pin 30, and the output pressure Pi is passed through the feedback circuit 20 to the spool 31.
and the pin 30, so if Pi becomes excessive, the spool 31 is moved to the right, so Pi automatically decreases and is compensated for.

The servo booster 9 controls the displacement qcc/rev of the variable displacement pump 5 in accordance with Pi, so that the variable pump cutoff displacement control shown in FIG. 4 is performed by the combination of the cutoff control valve 11 and the servo booster 9.

Furthermore, when the switching valve 2 is operated, hydraulic oil is not supplied to the switching valve 1 on the actuator 3 side, and only one actuator 4 is operated, and the capacity of the variable displacement pump 5 is cut off by detecting the pump discharge pressure Pp. controlled.

The present invention has been described in detail above, and includes one actuator 4, the other actuator 3 that operates at a maximum operating pressure P1* lower than the maximum operating pressure P2* of this actuator 4, and the discharge side of the variable displacement pump 5. A switching valve 1 is provided to communicate the pipes A and B of the actuator 3 with the tank 14 when in neutral and actuate the actuator 3 by switching, and a switching valve 1 is provided on the discharge side of the variable displacement pump 5 to operate the switching valve 1 when in neutral. Supplying oil and actuator 4
A switching valve 2 that cuts off the supply of hydraulic oil to the switching valve 1 side when switching, a shuttle valve 8 provided in the circuit of the actuator 3 that is activated by operation of the switching valve 1, and a charge pump 12.
It has a pump port 16, an output port 18, a drain port 23, and a pressure port 17 which is communicated with the output side of the shuttle valve 8 and into which the operating pressure P1 of the actuator 3 is introduced when the charge pressure Ps of the actuator 3 is introduced, and is variable. A pin 29 that moves due to the discharge pressure Pp of the displacement pump 5, and a pin that has a larger diameter than the pin 29 and moves the spool 3i against the spring 35 due to the pressure of the pin 29 and the operating pressure P of the actuator 3 from the shuttle valve 8. 30 and communicating the output port 18 with a pressure chamber between the pin 30 and the spool 31 via a feedback circuit 20;
A servo booster 9 connected to the discharge side of the charge pump 12 to control the capacity of the variable displacement pump 5, and a cut-off control valve 11 provided in one circuit of the servo booster 9.
This is a capacity control device for a hydraulic pump characterized in that it is equipped with a servo pilot spool valve 10 that turns on and off the circuit according to the output pressure Pi from the pump.

Therefore, when the switching valve 2 is in the neutral state and only the other actuator 3 is operated, and the pump discharge pressure Pp is low, the spool 31 is pushed by the spring 35 and moves, and the pump port 16 is communicated with the output port 18. Then, the output pressure P
When i is equal to the charge pressure Ps and the operating pressure Pi of the actuator 3 is zero (when using Koshin)
The pump discharge pressure Pp increases and this pressure causes the pin 29.
30, the spool 31 moves against the spring 35, and the communication between the pump port 16 and the output port 18 is cut off, and the output port 18 is communicated with the drain port 23, and the output pressure Pi is reduced.
decreases, and actuator 3 is further activated, resulting in P□=
When the pressure becomes Pp, the spool 31 is moved via the pin 30, and the output pressure Pi decreases.

Furthermore, since the output pressure Pi is guided through the feedback circuit 20 to the pressure chamber between the spool 31 and the pin 30, if the output pressure Pi becomes excessive, the spool 31 is moved against the spring 35 and the output pressure Pi is detected. It will be cut-off controlled.

Furthermore, when the switching valve 2 is switched, hydraulic oil is not supplied to the switching valve 1 on the actuator 3 side, and only one actuator 4 is operated, and the capacity of the variable displacement pump 5 is cut off by detecting the pump discharge pressure Pp. controlled.

Thus, the present invention automatically lowers and compensates the cut-off setting of the cut-off control device of the variable displacement hydraulic pump 5 depending on the type of actuating actuator.

The servo booster 9 performs variable pump cutoff capacity control by the cutoff control valve 11 controlled in this manner.

In this way, the capacity of the variable displacement hydraulic pump 5 is cut-off controlled by detecting the pump discharge pressure Pp when the switching valve 1 is neutral, and when the switching valve 1 is switched, the load pressure P□ of the actuator 3 is controlled. It can be changed automatically through the shuttle valve 8.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the configuration of the present invention - an embodiment, Fig. 2 is a longitudinal sectional view of the cutoff control valve, Fig. 3 is a characteristic diagram of the cutoff control valve, and Fig. 4 is a servo booster and the cutoff control valve. FIG. 5 is a variable displacement pump, 8 is a shuttle valve, 9 is a servo booster, 11 is a cut-off control valve, and 10 is a servo pilot spool valve.

Claims (1)

[Scope of utility model registration request] One actuator 4, the other actuator 3 that operates at a maximum operating pressure P1* lower than the maximum operating pressure P2* of this actuator 4, and the piping A of the neutral actuator 3 that is provided on the discharge side of the variable displacement pump 5. ,
A switching valve 1 that communicates B with a tank 14 and operates the actuator 3 by switching, and a switching valve 1 that is provided on the discharge side of the variable displacement pump 5 and that supplies hydraulic oil to the switching valve 1 when in neutral and switches the actuator 4. A switching valve 2 that cuts off the supply of hydraulic oil to the switching valve 1 side, a shuttle valve 8 provided in the circuit of the actuator 3 that is activated by the operation of the switching valve 1, and a charge EEPS of the charge pump 12 are introduced. It has a pump port 16, an output caponide 18, a drain port 231, and a pressure port 17 which is communicated with the output side of the shuttle valve 8 and into which the operating pressure P of the actuator 3 is introduced, and which is connected to the discharge pressure of the variable displacement pump 5. The pin 30 has a diameter larger than that of the pin 29 and moves the spool 31 against the spring 35 by the pressure of the pin 29 and the operating pressure P1 of the actuator 3 from the shuttle valve 8, and the output port. 18 is connected to a pressure chamber between pin 30 and spool 31 via feedback circuit 20, and a servo booster is connected to the discharge side of charge pump 12 to control the capacity of variable displacement pump 5. 9 and a servo pilot spool valve 10 which is provided in one circuit of the servo booster 9 and controls the circuit using the output pressure Pi from the cut-off control valve 11. Device.