JPH0566381U - Unload relief valve - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the high voltage of the actuator circuit from acting on the accumulator circuit when used in series with the actuator circuit and on the upstream side of the actuator circuit. [Structure] The on-off valve 37 depending on the pressure of the accumulator 5
The switching valve 29 is opened and closed by opening and closing the opening and closing valve 37.
Is configured to be switched and operated between a first position where the pump port 21 and the accumulator port 22 communicate with each other and a second position where the pump port 21 communicates with the actuator circuit.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an unload relief valve used in an accumulator circuit.

[0002]

[Prior Art]

 The accumulator circuit is used, for example, for controlling winch clutches and brakes in hydraulic cranes.

In this accumulator circuit, it is necessary to replenish (accumulate) the pressure oil from the pump according to the decrease in the accumulator pressure accompanying the discharge of the pressure oil.

Therefore, in general, an unload relief valve is provided in the accumulator circuit, and when the accumulator pressure drops below a set value, the valve is closed to supply pump discharge oil to the accumulator, and the accumulator pressure is set to the set value. While maintaining, the pump discharge oil is returned to the tank through the unload relief valve.

Conventionally, as an unload relief valve used for such an application, the one disclosed in Japanese Utility Model Laid-Open No. 59-15866 is known.

Explaining this with reference to FIG. 5, the pump port 2 connected to the pump 1 and the tank port 3 connected to the tank are connected by a tank passage 4, and the pressure of the accumulator 5 is connected to the tank passage 4. When the accumulator pressure is within the set value, the on-off valve 6 is opened to communicate (unload) the pump port 2 with the tank port 3 to reduce the accumulator pressure. It is known that the valve 6 is sometimes closed so that the pump port 2 communicates with the accumulator port 8 via the accumulator passage 7 (accumulates pressure). Reference numeral 9 is a check valve provided in the accumulator passage 7.

[0007]

[Problems to be solved by the device]

 On the other hand, if the pump 1 is dedicated to accumulator pressure accumulation, it is disadvantageous in terms of equipment, piping, consumption torque, etc. Therefore, there is a demand to use the pump 1 for other hydraulic actuators.

When such a pump-combined circuit configuration is adopted, as shown in FIG. 6, the valve 10 and the actuator circuit are provided so that stable operation can be obtained while avoiding fluctuations in the flow rates of the accumulator circuit and the actuator circuit. It is desirable to provide 11 and 11 in series.

According to this series circuit, the actuator circuit 11 is supplied to the accumulator 5 during the pressure accumulating action (normally, a long cycle of every 30 seconds to 60 seconds is performed for a short time of about 1 second to 3 seconds each time). Since the supply of oil is stopped, it is necessary for the circuit 11 to be able to suspend operation. In the figure, as an example thereof, an actuator circuit for driving a compressor motor 12 for a cabin cooler of a crane and a fan motor 13 for an oil cooler is shown.

In this case, when the unload relief valve 10 is provided on the downstream side of the actuator circuit 11 as shown by the solid line in FIG. 6, when the load pressure of the actuator circuit 11 rises, the main relief valve 14 Is activated and the supply of oil to the accumulator 5 is stopped, causing troubles such as the inability of the accumulator 5 to accumulate pressure.

Therefore, the unload relief valve 10 needs to be provided on the upstream side of the actuator circuit 11 as shown by the phantom line in FIG.

However, the following problems occur here.

In the conventional unload relief valve 11, the outlet port is only the tank port 3. Therefore, when the valve 10 is used in the above-mentioned pump-combined circuit, the tank port 3 is used as an actuator port and the actuator circuit 11 is provided here. It will be connected.

However, in this way, when the load pressure of the actuator circuit 11 rises, even if the passage of the unload relief valve 10 opens, the oil does not flow into the actuator circuit 11 because the outlet side pressure is high. It may flow to the accumulator circuit side, and high voltage may act on the circuit.

Therefore, conventionally, the unload relief valve 10 is used on the upstream side of the actuator circuit 11, that is, one pump 1 is used as both the accumulator 5 and the other actuator circuit 11. Actually I couldn't.

Therefore, the present invention provides an unload relief valve in which the high pressure of the actuator circuit does not affect the accumulator circuit even when used upstream of the actuator circuit.

[0017]

[Means for Solving the Problems]

 The present invention comprises a pump port connected to a pump, an accumulator port connected to an accumulator, an actuator port connected to a hydraulic actuator circuit, a tank port connected to a tank, the pump port and an accumulator port. A switching valve that operates by switching between a first position for communicating and a second position for communicating the pump port and the actuator port, and a first pressure chamber that applies pressure to the switching valve toward the first position. A second pressure chamber that applies pressure to the switching valve toward the second position, a spring provided in the first pressure chamber, and a pump pressure introduction passage that introduces pump pressure into both pressure chambers. When the pressure in the tank passage connecting the first pressure chamber and the tank port and the accumulator exceeds a set value, the valve is opened to operate the first valve. Off valve for communicating the pressure chamber to the tank, is shall such comprises a differential pressure holding means for holding the high pressure than the second pressure chamber when the valve is opened in the opening and closing valve first pressure chamber.

[0018]

[Action]

 According to the above configuration, when the accumulator pressure is equal to or lower than the set value, the opening / closing valve is closed, the communication between the first pressure chamber and the tank is cut off, and the first pressure chamber and the second pressure chamber have the same pressure (pump pressure). ). Therefore, at this time, the switching valve is set to the first position by the spring, so that the pump oil is supplied (accumulated) to the accumulator through the accumulator port.

On the other hand, when the accumulator pressure reaches the set value, the opening / closing valve is opened by the accumulator pressure and the first pressure chamber communicates with the tank. At this time, since the second pressure chamber is maintained at a higher pressure than the first pressure chamber by the differential pressure holding means, the switching valve switches to the second position. For this reason, the pump oil supply direction switches from the accumulator to the actuator circuit.

In this way, the accumulator acts to accumulate pressure, and the pump oil can be used for driving the actuator except when accumulating pressure.

That is, one pump can be used for both the accumulator and the other actuator. Moreover, since the accumulator and the actuator circuit are hydraulically separated by the switching valve, the high pressure of the actuator circuit does not act on the accumulator circuit.

[0022]

【Example】

 An embodiment of the present invention will be described with reference to FIGS.

1 and 2 show a specific structure of the unload relief valve 20 according to this embodiment, FIG. 3 shows a circuit configuration of the valve 20, and FIG. 4 shows the valve 20 used upstream of the actuator circuit 11. The circuit configurations that also serve as pumps are shown. In FIGS. 3 and 4, the same parts as those in FIGS. 5 and 6 are designated by the same reference numerals.

1 to 3, 21 is a pump port connected to the pump 1, 22 is an accumulator port connected to the accumulator 5, 23 is an actuator port connected to the actuator circuit 11, and 24 is a tank. The connected tank port 25 is a pressure introduction port for introducing the accumulator pressure.

A spool-type switching valve 29 is provided between the inflow passage 26 connected to the pump port 1, the accumulator passage 27 connected to the accumulator port, and the actuator passage 28 connected to the actuator port 23.

The switching valve 29 has a first position (a position in FIG. 3) that allows the inflow passage 26 and the accumulator passage 27 to communicate with each other as shown in FIG. 1 when the spool 30 strokes left and right. , As shown in FIG. 2, the inflow passage 26 and the actuator passage 28 are switched between a second position (position B in FIG. 3) for operation.

Therefore, when the switching valve 29 is in the first position, when the pump oil is switched to the accumulator 5 via the inflow passage 26 and the accumulator passage 27 and to the second position, the pump oil is removed. It is supplied to the actuator circuit 11 via the inflow passage 26 and the actuator passage 28, respectively. Reference numeral 31 is a check valve provided in the accumulator passage 27.

The switching valve 29 includes a first pressure chamber 32 for applying a pressure toward the first position to the spool 30 on one side (right side in the drawing) of the spool 30, and a second pressure chamber for the spool 30 on the opposite side. A second pressure chamber 33 that applies pressure toward the position is provided, and a spool pressure introduction passage 34 that introduces pump pressure into the pressure chambers 32 and 33 on both sides is provided in the spool 30 at both the first and second positions. ing.

The pump pressure introducing passage 34 has a central flow passage 34 a provided at the center of the spool 30, a communication hole 34 b for communicating the inflow passage 26 and the central flow passage 34 a, and a central hole 34 a. It is constituted by a throttle flow passage 34c that communicates with the pressure chamber 32 and a flow passage 34d that communicates the central hole 34a with the second pressure chamber 33.

A spring 35 is provided in the first pressure chamber 32, and when both pressure chambers 32 and 33 have the same pressure (pump pressure), the force of the spring 35 causes the spool 30 to move to the first position. To be done.

On the other hand, the first pressure chamber 32 is connected to the tank port 24 via a tank passage 36, and the tank passage 36 is provided with an opening / closing valve 37 for opening and closing the passage 36.

The on-off valve 37 includes a poppet 38 to which a spring force is applied and a pilot spool 39 that pushes the poppet 38 to open the valve. A pilot chamber 40 that applies a back pressure to the pilot spool 39 introduces an accumulator pressure. Connected to port 25. That is, the pressure of the accumulator 5 is applied to the opening / closing valve 37 as a valve opening force.

A throttle channel 36 a is provided in the middle of the tank passage 36. The flow passage diameter of the throttle flow passage 36a (for example, 1.2 mm) is larger than the flow passage diameter (for example, 0.8 mm) of the throttle flow passage 34c communicating with the first pressure chamber 32 in the pump pressure introduction passage 34 described above. It is set to a large size.

In this configuration, when the pressure of the accumulator 5 is equal to or lower than the set value, the valve opening force applied to the opening / closing valve 37 is smaller than the spring force (the spring force is set as such), so that the valve 37 close.

In this state, the first pressure chamber 32 is shut off from the tank, and the same pressure chamber 32 becomes the same pressure (pump pressure) as the second pressure chamber 33. Therefore, the switching valve 29 receives the force of the spring 35. Thus, it is set to the first position shown in FIG.

As a result, the pump oil is supplied to the accumulator 5 and the pressure accumulation action is performed.

When the accumulator pressure reaches the set value by this pressure accumulation action, the valve opening force of the opening / closing valve 37 increases and the valve 37 opens, so that the first pressure chamber 32 communicates with the tank and the inside of the pressure chamber 32 is closed. Oil is dropped into the tank through the tank passage 36.

At this time, the oil in the second pressure chamber 33 also flows into the first pressure chamber 32 through the pump pressure introduction passage 34 at the same time, but the diameter of the throttle channel 34c is smaller than that of the throttle channel 36a. Since it is sufficiently small, a differential pressure is generated before and after the throttle channel 34c. That is, since the second pressure chamber 33 is kept at a higher pressure than the first pressure chamber 32, the spool 30 is pushed to the right side in the drawing and the switching valve 29 is switched to the second position shown in FIG.

As a result, the accumulator passage 27 is closed and the actuator passage 28 is opened with respect to the inflow passage 26, so that the supply of pump oil to the accumulator 5 is stopped, and instead the pump oil is supplied to the actuator circuit 11. Supplied.

In this state, the accumulator circuit and the actuator circuit 11 are hydraulically shut off by the switching valve 26, so that the high pressure generated in the actuator circuit 11 does not act on the accumulator circuit. That is, as shown in FIG. 4, it is actually possible to adopt a series circuit configuration in which the unload relief valve 20 is provided upstream of the actuator circuit 11 and also serves as a pump.

At this time, the outlet portion of the inflow passage 26 is opened to the accumulator passage 27 side only slightly (S in FIG. 3 indicates a throttle passage due to this slight opening), and the pump pressure introducing passage is formed. The introduction of pump oil into 34 continues. However, the accumulator passage 27 is kept closed by the back pressure of the check valve 31.

After that, when the accumulator pressure decreases due to the release of oil from the accumulator 5, the opening / closing valve 37 closes and the first pressure chamber 32 is shut off from the tank, so that both pressure chambers 32 and 33 are separated. The pressure becomes equal again, and the force of the spring 35 causes the switching valve 29 to return to the first position to start the pressure accumulation action.

By the way, in the above embodiment, the poppet valve is used as the opening / closing valve 37, but a spool valve may be used instead.

[0044]

[Effect of the device]

 As described above, according to the present invention, the opening / closing valve is opened / closed by the accumulator pressure, and by opening / closing the opening / closing valve, the switching valve is connected to the position where the pump port and the accumulator port are communicated (accumulator pressure accumulation position) and the pump. Since the actuator is switched between the position where the port and the actuator circuit communicate (actuator drive position), the accumulator circuit and the actuator circuit are hydraulically disconnected, and the high pressure generated in the actuator circuit is generated. There is no fear of using it for.

In other words, it is actually possible to connect the unload relief valve in series with another actuator circuit to form a circuit configuration that also serves as one pump.

[Brief description of drawings]

FIG. 1 is a sectional view showing a specific structure of an unload relief valve according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a state in which a switching valve of the same valve is set at a position different from that in FIG.

FIG. 3 is a circuit configuration diagram of the valve.

FIG. 4 is a circuit configuration diagram when the valve is used by being connected in series with another actuator circuit.

FIG. 5 is a circuit configuration diagram of a conventional unload relief valve.

FIG. 6 is a circuit configuration diagram for explaining a problem when the valve is connected to another actuator in series and used.

[Explanation of symbols]

 1 Pump 5 Accumulator 11 Actuator Circuit 21 Pump Port 22 Accumulator Port 23 Actuator Port 24 Tank Port 29 Changeover Valve 30 Changeover Valve Spool 32 First Changeover Pressure Chamber 33 Same Second Pressure Chamber 35 First Pressure Chamber Spring 34 Pump Pressure introducing passage 36 Tank passage 37 Opening / closing valve 34c, 36a Throttle flow passage constituting differential pressure holding means

Claims (1)

[Scope of utility model registration request] 1. A pump port connected to a pump, an accumulator port connected to an accumulator, an actuator port connected to a hydraulic actuator circuit, a tank port connected to a tank, the pump port and an accumulator port. A switching valve that operates by switching between a first position for communicating with the pump port and a second position for communicating with the pump port and the actuator port, and a first pressure that applies a pressure toward the first position to the switching valve. A chamber, a second pressure chamber that applies pressure toward the second position to the switching valve, a spring provided in the first pressure chamber, a pump pressure introduction passage that introduces pump pressure into both pressure chambers, When the pressure in the tank passage connecting the first pressure chamber and the tank port and the pressure in the accumulator exceeds a set value, the valve is opened to operate the first pressure. An opening / closing valve for communicating the force chamber with the tank, and a differential pressure holding means for holding the second pressure chamber at a higher pressure than the first pressure chamber when the opening / closing valve is opened are provided. Load relief valve.