JPS6030835B2 - Hydraulic drive circuit control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a hydraulic drive circuit.

Conventionally, in a hydraulic drive circuit for driving a rock drilling machine, etc., an actuation control valve is interposed in a hydraulic passage between an actuator such as a hydraulic sill and a hydraulic pump driven by a fluid motor. Some actuators operate and stop by opening and closing the actuator.

However, when the operation control valve is closed to temporarily stop the actuator operation, the hydraulic pump is driven in the same state as when the actuator is operating, returning oil to the tank, and driving the fluid motor. In addition to wasting air, etc., unnecessary exhaust noise is generated.

On the other hand, it is conceivable to completely stop the hydraulic pump to eliminate the above-mentioned problem, but this poses a problem in that preparation time is required to restart the hydraulic pump.

In view of this, the present invention provides a throttle valve having pilot pressure receiving surfaces of a large area and a small area in the pipe line for supplying the fluid outside the fluid motor, and the fluid pressure on the outlet side of the throttle valve is provided on both pilot pressure receiving surfaces. The present invention provides a control device for a hydraulic drive circuit that ensures that the throttle valve is switched by switching the operation control valve by applying hydraulic pressure between the hydraulic pump and the operation control valve. This aims to reduce fluid consumption and reduce exhaust noise.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below based on embodiments with reference to the drawings. Figure 1 shows the hydraulic drive circuit 1 used to drive the rock drilling machine.
In this figure, 2 is an actuator such as a hydraulic cylinder operated by hydraulic pressure, 3 is a hydraulic pump that drives the actuator 2, and 4 is a wind center type operation control installed in a hydraulic passage 5 between the actuator 2 and the hydraulic pump 3. valve, 6
7 is a fluid motor that drives the hydraulic pump 3, and 7 is a throttle valve provided in a conduit 8 that supplies fluid to the fluid motor 5.

In this example, an air motor is used as the fluid motor 6, and in FIG. 1, 9 is an air source, 10 is a two-boat switching valve provided between the air source 9 and the throttle valve 7, and Reference numeral 11 is a leaf valve that regulates the upper limit of the oil pressure between the hydraulic pump 3 and the operation control valve 4.

The throttle valve 7 is equipped with a pilot pressure receiving surface 12 having a large area S, which will be described later based on FIG. 2, and a pilot pressure receiving surface 13 having a small area S2. A fluid pressure pilot circuit 14 that transmits the fluid pressure P on the outlet side of the throttle valve, and a pilot pressure receiving surface 13 with a small area.
A hydraulic pilot circuit 15 is provided for transmitting the hydraulic pressure P2 between the hydraulic pump 3 and the operation control valve 4.

Further, the throttle valve 7 is provided with a first pilot circuit 16 and a second pilot circuit 17 that transmit fluid pressure on the throttle valve inlet side. That is, in the throttle valve 7 shown in FIG. 2, 20 is a housing having a fluid inlet 21 and an outlet 22, and 23 is a cover with a small diameter cylindrical portion 24 extending upward.

Cavity 2 composed of housing 20 and cover 23
5 has the spool valve 26 provided with the large-area pilot pressure receiving surface 12 on the lower surface, and the cylindrical portion 24 has the spool valve 26 provided with the large pilot pressure receiving surface 12 on the upper surface.
・Plunger 27 provided with a pilot pressure receiving surface 13 of the area
is stored. Then, the fluid pressure pi. The hydraulic pilot circuit 14 is constructed by boring a passage in the housing wall that passes through the outlet 22 and the lower end of the cavity 25, and the hydraulic pilot circuit 15 is constructed by opening a passage in the housing wall that passes through the outlet 22 and the lower end of the cavity 25. and the cylindrical portion 24 of the cover 23 are connected by a pipe, and the fluid pressure pilot circuit 14
A diaphragm 28 is interposed in the diaphragm 28 so that the amount of diaphragm can be adjusted. The spool valve 26 also has first pilot pressure receiving surfaces 29 having equal pressure receiving areas on the upper and lower outer peripheries, respectively.
and a second pilot pressure receiving surface 30 are formed.

The first pilot circuit 16 and the second pilot circuit 17, which transmit the fluid pressure on the throttle valve inlet side to the pilot pressure receiving surfaces 29 and 30, are each constructed by having a vent hole in the housing wall. The aperture 31 is equipped with a diaphragm so that the amount of aperture can be adjusted. In addition, in FIG. 2, 32 is a pressure relief hole. Next, the action will be explained.

In FIG. 3, line A represents the relationship between fluid pressure P and oil pressure P2 when the actuation control valve 4 is in the neutral position, and line B represents the relationship between P and P2 when the actuation control valve 4 is in the offset position. The hysteresis loop C represents the P and P2 relationship in the actual operation in the above embodiment, and the line D represents the P when the throttle valve 7 is switched.
, P2 relationships are shown respectively. Note that the starting pressure of the fluid motor 6 in the example is set to 0.5 to 2.0 kg/c Sakaki, and the fluid pressure P when the actuator is not in operation is determined by fluid consumption, exhaust noise, and motor speed. 0 considering the pressure.
A value of 5 to 1.5 k9/plane is desirable, while a suitable P value during operation is 4 to 5.5 k9/plane. To make the following explanation easier to understand, P when not in operation is assumed to be 1.0k9/ground, and P when activated is assumed to be 4k9/ground. Further, the rock drill is set to operate at a minimum oil pressure P2=9k9/ground. First, the reason why the throttle valve 7 is switched using P and P2 in the above embodiment is as follows.

That is, as shown by line A and line B in FIG.
2 is the hydraulic pump 3 when the operation control valve 4 is in the neutral position.
Since the entire amount of oil discharged from the pump is returned to the tank, it is lower than when it is in the offset position, but the fluid pressure P is as high as 4k9/Sakaki, and the hydraulic pump 3 is operated at high rotation speed. At this time, even if the operation control valve 4 is in the neutral position, the oil pressure P2 will be 20 kg due to the influence of pipe resistance etc.
/ is rising. Therefore, when the fluid pressure P is lk9/ground, the neutral oil pressure P2=6kg/, and the minimum pressure P2 at which the rock machine operates is 9k9/carp.
If the switching setting pressure Pc is 6k9/Pc<9k9/ground, when the operation control valve 4 is set to the neutral position after operating the rock drill, the oil pressure P2 at that time will be 20k9/2 and the above. Since the pressure is higher than the set pressure Pc, the throttle valve 7 cannot return from open to throttle. Therefore, in the present invention, the throttle valve 7 is switched between the pilot pressures of both the fluid pressure P and the oil pressure P2, and the fluid pressure P is placed on the pilot pressure receiving surface 12 with a large area, and the oil pressure P2 is placed on a small area with the pilot pressure receiving surface 12. The pressure is transmitted to the pilot pressure receiving surface 13 of the pilot pressure receiving surface 13. Note that the area ratio of both pilot pressure receiving surfaces 12 and 13 in the above embodiment is S:S2=7.5:1. To explain the operation of the above embodiment, first, when starting the fluid motor 6, when the switching valve 10 is opened, the fluid pressure Po on the throttle valve inlet side is increased to the first and second pilot circuits 16, 17. However, since the second pilot circuit 17 is provided with the throttle 31, the increase in pilot pressure acting on the second pilot pressure receiving surface 30 is delayed. , the spool valve 26 of the throttle valve 7 is temporarily moved to the open position, and a high starting pressure acts on the fluid motor 6.

This is 0.5 to 2.0 kg to the starting pressure of the fluid motor 6.
If the fluid pressure P when the throttle valve 7 is in the throttle state is set to lk9/, the fluid motor 6 may not start. This is to ensure that the engine starts properly. Note that once the fluid motor 6 is started, it rotates even at a low pressure of about 0.5 k9/m. Then, the combined force of the pressure acting on the second pilot pressure receiving surface 3 and the pressure acting on the large area pilot pressure receiving surface 12 from the throttle valve outlet side via the fluid pressure pilot circuit 14 is generated. When the force becomes larger than the force acting on the 1-pilot pressure receiving surface 29, the spool valve 26 returns to its original throttle position, and the starting operation is completed. Therefore, the hydraulic drive circuit 1 is in a state when the actuator is not operating, with the fluid motor 6 rotating at a low speed, that is, in the state at point C on the cycle line C in FIG. Next, when the actuation control valve 4 is switched from the neutral position to the offset position, the oil pressure P2 rises and when it exceeds point C2 on the D line, the force P2×S2 acting on the small area pilot pressure receiving surface 13 becomes large. The area becomes larger than the force P,×S, which acts on the pilot pressure receiving surface 12, and the spool valve 26 moves from the throttle position to the open position.

At this time, the throttle 28 serves to delay the increase in pilot pressure acting on the large-area pilot pressure receiving surface 12, and the throttle valve 7 ensures that the spool valve 26 is switched without stopping in the middle. Subsequently, due to the increase in the fluid pressure P, the oil pressure P
2 also rises and reaches point C3 on loop C, and fluid motor 6
This is the state when the actuator is activated by rotating at high speed.
Then, when the operation of the actuator 2 is temporarily stopped, when the operation control valve 4 is switched from the offset position to the neutral position, when the oil pressure P2 decreases and exceeds point C4 on line D, P. S. >P2S2, spool valve 2
6 moves from the open position to the aperture position.

At this time, the throttle 28 functions to delay the drop in the pilot pressure acting on the large-area pilot pressure receiving surface 12, contrary to the case described above, and the throttle valve 7 ensures that the spool valve 26 does not stop in the middle. Switch. Then, as the fluid pressure P, decreases, the oil pressure P2 also decreases, and C, on the loop C,
At this point, the actuator is in a non-operating state in which the fluid motor 6 is rotated at a low speed. As described above, according to the present invention, the throttle valve is connected to the hydraulic pressure between the operation control valve and the hydraulic pump;
Since the fluid pressure on the outlet side of the throttle valve is used for switching, the throttle valve is reliably switched by switching the operation control valve, and when the actuator operation is temporarily stopped, the fluid flow rate can be throttled by the throttle valve. This provides an excellent effect of reducing fluid consumption and exhaust noise.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, in which FIG. 1 is a hydraulic drive circuit diagram, FIG. 2 is a central vertical sectional view of a throttle valve, and FIG. 3 is a graph showing the relationship between oil pressure and fluid pressure. DESCRIPTION OF SYMBOLS 1... Hydraulic drive circuit, 2... Actuator, 3... Hydraulic pump, 4... Operation control valve, 5... Hydraulic passage, 6 ...Fluid motor, 7 ... Throttle valve, 8 ... Pipe line, 1
2...Large area pilot pressure receiving surface, 13...
...Small area pilot pressure receiving surface, 14...Fluid pressure pilot circuit, 15...Hydraulic pilot circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An operation control valve is provided in a hydraulic passage between a hydraulic pump driven by a fluid motor and an actuator driven by the hydraulic pump, and a large area and a small area are provided in a pipe line that supplies fluid to the fluid motor. A hydraulic pilot circuit is provided for transmitting the hydraulic pressure between the hydraulic pump and the operation control valve to the small pilot pressure receiving surface of the throttle valve, and a hydraulic pilot circuit is provided to the large pilot pressure receiving surface of the throttle valve. A control device for a hydraulic drive circuit, comprising a fluid pressure pilot circuit that transmits fluid pressure on the outlet side of a throttle valve.