JPS5922322Y2 - Valve device for driving single-acting cylinder piston device for lifting heavy objects - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a valve device for driving a single-acting cylinder-piston device for lifting heavy objects such as working machines such as tractors.

As a drive system for this type of single-acting cylinder piston device, Japanese Utility Model Application No. 52-64294 discloses a circuit configuration as shown in FIG.
The publication discloses a circuit configuration as shown in FIG.

In the conventional system shown in FIG.
At the same time, the main relief valve 3 is connected to the solenoid switching valve 4.
The pressurized flow path 2 is connected to a single acting cylinder piston device 7 via a pilot operated check valve 5 and a check throttle valve 6.
The pilot pressure generated by a separately provided pilot relief valve 9 is connected to the pressurized cylinder chamber 8 of the pressurized cylinder chamber 8 and is forced to act on the pilot operated check valve 5 only when the electromagnetic switching valve 4 is switched to the downward position. It is designed to open.

Therefore, in this drive system, the electromagnetic switching valve 4 is installed in series with the pressurizing flow path 2 as the main path or the return flow path, so that the electromagnetic switching valve itself controls the inflow flow rate from the pump 1 to the pressurizing cylinder chamber 8. and regulates the maximum value of the flow rate outflow from the pressurized cylinder chamber 8 to the tank 10, and is therefore unsuitable for driving a single-acting cylinder piston device at a large flow rate. In addition to the drawback of having to make the valve large, it also requires two pilot relief valves, one for securing pilot pressure to the pilot-operated check valve and the other for securing the driving force for the cylinder piston device 7. This method has the disadvantage that two relief valves are required, and therefore the valve structure surrounding the device must be enlarged.

In addition, the conventional one shown in FIG. 2 is provided with a shut-off type solenoid switching valve 4' for starting the rise, which shuts off the flow path during operation, between the pressurized flow path 2, which is the main path, and the tank 10. Pressure oil pressure is generated and extinguished to the check valve 6a in the pressurized flow path 2 that is opened, and the flow of pressure oil flowing out to the tank 10 through the throttle valve 6b for controlling the descending speed is opened and closed by the solenoid check valve 5' for starting the descent. Therefore, when the electromagnetic switching valve 4' is inactive, the flow of pressure oil to be sent to the cylinder chamber 8 passes through the electromagnetic switching valve 4'. It is necessary to use a large solenoid device that can overcome the flow force.

This idea was made with the aim of improving the various drawbacks of the prior art as described above, and it is necessary to use electromagnetic technology in both the pressurizing flow path from the pump to the pressurized cylinder chamber and the return flow path from the pressurized cylinder chamber to the tank. Instead of installing a switching valve, a pilot-operated check valve is placed in the return flow path as a check valve to allow the pressure oil flow from the pressurized cylinder chamber to flow out to the tank, and a pilot-operated check valve is installed between the pressurized flow path and the tank. A relief valve is connected, and the pilot port of the pilot-operated check valve and the vent port of the relief valve are selectively connected to the pressurizing flow path or the return flow path using an electromagnetic switching valve. By switching the operation between stopping and lowering, and at the same time giving this electromagnetic switching valve a unique function for each switching position, the vent flow of the relief valve is individually controlled at each position, and the relief valve The function of the main relief valve is to ensure the driving force of the cylinder device during the upward movement, and the function of the pilot relief valve is to ensure the pilot pressure for the opening operation of the pilot operated check valve during the downward movement. Furthermore, during stop operation, the vent port of the renouf valve is communicated with the tank by the neutral position function of the electromagnetic switching valve, and the pump is unloaded via this relief valve. The present invention provides a valve device for driving a device.

In the valve device of this invention, only the pilot flow of the pilot-operated check valve and the vent flow of the relief valve flow through the electromagnetic switching valve, so a small and highly responsive electromagnetic switching valve can be used. Since there are no solenoid switching valves located in the pressurization flow path, return flow path, or pump unload flow path, only the check valves, pilot-operated check valves, and relief valves in these flow paths can be enlarged. If used for flow rates, a system for large flow rates can be constructed using a small electromagnetic switching valve.

To describe this invention in detail together with illustrated embodiments, FIG. 3 is a hydraulic circuit diagram of a drive system for a single-acting cylinder piston device in which the valve device of this invention is shown surrounded by a chain line, and FIG. FIG. 5 is a vertical cross-sectional view of one embodiment of the apparatus, and is a view taken along the line II--II in FIG. 4.

In FIG. 3, the valve device of the present invention surrounded by chain lines is connected to the pressurizing flow path 2 between the pressurizing cylinder chamber 8 of the single-acting cylinder piston device 7 and the pump 1, and A check valve 20 that allows oil to flow into the pressurized cylinder chamber while closing against reverse flow is connected to the return passage 15 from the pressurized cylinder chamber 8 to the tank 10, and
- A pilot-operated check valve 30 that drains the pressurized oil in the pressurized cylinder chamber 8 to the tank 10 when pressure is applied, and a tank 10 that is branched from the pressurized flow path 2 between the pump 1 and the check valve 20. a relief valve 40 that is interposed in the unload flow path 14 leading to the pressurization flow path 2 and controls the pressure of the pressurization flow path 2; a pilot port 31 of the pilot operation check valve 30; and a vent port 41 of the relief valve 40.
an electromagnetic switching valve 50 for selectively connecting the pressurizing flow path 2 and the tank 10 to switch between raising, lowering, and stopping operations of the piston of the single-acting cylinder-piston device;
And be prepared.

The check valve 20 is the vent port 4 of the relief valve 40.
1 is shut off, the discharge pressure oil of the pump 1 received at the inlet port 11 pushes the pressurized flow path 2 open, which rises to the set pressure of the relief valve 40. Therefore, the pressure oil at this set pressure is transferred to the cylinder port. 12 into the pressurized cylinder chamber 8 of the single-acting cylinder piston device 7 to raise the piston, and when the pressure received from the pressurized cylinder chamber 8 side becomes greater than the pressure received from the pressurized flow path 2. Shut off pressure oil flow.

Therefore, the vent port 41 of the relief valve 40 is connected to the tank 10.
When the relief valve 40 is in a fully open state,
The check valve 20 is closed due to its own weight or load applied to the piston of the cylinder piston device 7, and the flow path between the pump 1 and the pressurized cylinder chamber 8 is cut off.

The pilot-operated check valve 30 communicates the pressurized cylinder chamber 8 with the return passage 15 to the tank 10 when the pilot port 31 receives a predetermined pressure, and no pressure is acting on the pilot port 31. Sometimes, this return passage 15 is blocked by a check valve body (36: Fig. 4).

In FIG. 3, a throttle valve 16 is disposed in the return passage 15, and this throttle valve 16 throttles the flow of pressure oil flowing out from the pressurized cylinder chamber 8 to the tank 10 when the return passage 15 is formed. This is for adjusting the lowering speed of the piston of the cylinder piston device 7, and is therefore provided as necessary.

The electromagnetic switching valve 50 selectively connects the vent port 41 of the relief valve 40 and the pilot port 31 of the pilot-operated check valve 30 to the pressurized flow path 2 on the discharge side of the pump 1 and the tank 10. Switch each valve 30 above.
It is for controlling the operation of each of 40.

That is, this electromagnetic switching valve 50 includes a lifting solenoid device 51 for sending pressure oil into the pressurizing cylinder chamber 8 of the cylinder piston device 7 to raise the piston, and a lifting solenoid device 51 for sending pressure oil into the pressurizing cylinder chamber 8 of the cylinder piston device 7 to raise the piston. A lowering solenoid device 52 for draining water into the tank 10 and lowering its piston, and a spool (53: Fig. 4 ), and the spool 53 communicates both the vent port 41 and the pilot port 31 with the tank 10 in the neutral state, and in the switching position when the lifting solenoid device 51 is energized. The vent port 41 is shut off and the pilot port 31 is communicated with the tank 10, and the vent port 41 is communicated with the tank 10 via the throttle 54 at the switching position when the lowering solenoid device 52 is energized. Above pilot port 3
1 is connected to the pressurizing flow path 2 on the discharge side of the pump 1.

Reference numeral 58 in FIG. 3 is a constriction part formed by the spool 53, and this constriction part 58 throttles the pilot pressure oil flowing out from the pilot port 31 to the tank to gradually return the pilot-operated check valve 30 to its closed state. This is to prevent the occurrence of shock when the piston of the single acting cylinder piston device 7 stops descending.

Therefore, when the ascending solenoid device 51 is energized, the vent port 41 of the relief valve 40 is blocked and the set pressure is not generated in the pressurizing flow path 2, and the pilot operated check valve 30 has its pilot port 31 connected to the tank 10.
As shown in FIG. 3, the flow of pressure oil flowing out from the pressurized cylinder chamber 8 side to the tank 10 is blocked.

As a result, the discharge pressure oil of the pump 1 flows from the pressurizing flow path 2 through the check valve 20 into the pressurizing cylinder chamber 8 at the pressure set by the relief valve 40, and the single acting cylinder piston device 7
the piston is raised at a predetermined pressure.

When the piston has risen to a height of pump 1
is unloaded and the set pressure no longer stands in the pressurizing flow path 2, so the piston of the cylinder piston device 7 is supported by the check valve 20 and stops supporting the load at that height.

Next, when the lowering solenoid device 52 is energized, the pilot port 31 of the pilot-operated check valve 30 is communicated with the pressurizing flow path 2, and the vent port 41 of the relief valve 40 falls into the tank 10 via the throttle 54. 54 generates back pressure in the vent flow of the relief valve 40, and as a result, a low pressure determined by the opening degree of the throttle 54 is generated in the pressurizing flow path 2 by the relief valve 40 and applied to the pilot port 31, and this becomes the pilot pressure. The pilot-operated check valve 30 is then opened, and a return flow path 15 from the pressurized cylinder chamber 8 to the tank 10 via the throttle 16 is formed.

As a result, the pressure oil in the pressurized cylinder chamber 8 is transferred to the tank 1 through the return flow path 15 due to the load applied to the piston.
0, and the piston descends at a speed determined by the throttle 16.

If the lowering solenoid device 52 is de-energized when the piston has descended to the height of
The pilot-operated check valve 30 therefore returns and closes off the return flow path 15 again, and the pump 1 is unloaded via the relief valve 40 so that the piston is supported by the check valve 20 in its height position. Stop descending.

In FIGS. 4 and 5, the specific structure of the valve device of the present invention shown in the area surrounded by the chain line in FIG. 3 is indicated by the same reference numerals.

That is, the check valve 20 has a seat 21 between the inlet port 11 and the cylinder port 12.
When a predetermined pressure is generated in the pressurized flow path 2 communicating with the inlet port 11, the check valve element 23 moves away from the seat against the spring 22 and closes the inlet port. 11 is communicated with the cylinder port 12.

The pilot operation check valve 30 is the B of the electromagnetic switching valve 50.
A pilot piston 32 receives pilot pressure from the pilot port 31 through the flow path 17 from the port 55 and receives pilot pressure from the pilot port 31, and a spring 35 receives the inserted poppet valve body 34.
The check valve body 3 is pressed against the seat 33 by the force of the check valve body 3.
6, the check valve element 36 is separated from the seat 33 by penetrating the check valve element 36 with a pin 37 at the tip of the pilot piston 32 and pushing back the poppet valve element 34 against the spring 35. Cylinder port 1
2 and the tank port 13 are opened.

Reference numeral 38 is a knob for manually operating the pilot piston 32, and this knob is provided when the piston needs to be manually lowered when the pump 1 is stopped.

The Noleaf valve 40 consists of a valve body 43 seated on a seat 42, a spring 44 that presses the valve body 43, and a setting mechanism 46 that adjusts the deflection of the spring 44 for the set pressure via a spring pusher 45. The vent port 41 is the solenoid switching valve 5
It communicates with the A port 56 of No. 0.

The electromagnetic switching valve 50 consists of a spool 53 whose neutral position is determined by a spring (not shown), and both ascending and descending solenoid devices 51 and 52 connected to the spool 53 via bushing pins, respectively. A restrictor 54 of a predetermined diameter is bored in the valve flange 57 at one end.

Further, the valve flange 59 at the other end forms a constriction part 58 that throttles the flow path from the B port 55 to the tank in the neutral state.

The throttle valve 16 is clearly shown in FIG. 5, and the throttle valve body 19, which is biased by a spring 18, is adapted to have its throttle opening degree adjusted by a knob 24.

In the valve device according to this invention, an appropriately determined back pressure can be applied to the vent flow of the relief valve 40 by the throttle 54 during the descending operation, and this allows the minimum necessary pilot pressure to be built up in the pressurized flow path. Pilot operated check valve 30
Since the electromagnetic switching valve 50 only switches between the pilot flow rate corresponding to this minimum necessary pilot pressure and the throttled vent flow rate of the relief valve 40, the electromagnetic switching valve 50 can be of small size. It is possible to control a main line with a large flow rate even by using a device, and in this case, only the main line check valve 20, pilot-operated check valve 30, and throttle valve 16 need be adapted for large flow rates, and large flow rates can be achieved. It also has the advantage of being easy.

Furthermore, in the valve device according to this invention, the relief valve 4
0 is to fully open to unload the pump when the electromagnetic switching valve 50 is neutral, and to generate the minimum necessary pilot pressure to open the pikes 1 to operation check valves 30 when the lowering solenoid device 52 is energized. Since the pressure is controlled at a sufficiently low level, there is an advantage that oil temperature rise and noise generation are reduced, unlike the conventional case where the main relief valve is constantly operated at high pressure.

Furthermore, in the valve device according to this invention, since the electromagnetic switching valve 50 only switches a small flow rate, the responsiveness of the operation is significantly improved, and it is clear that this is especially advantageous for a drive system with a large flow rate. be.

[Brief explanation of drawings]

1 and 2 are hydraulic circuit diagrams of a conventional single-acting cylinder piston device drive system, FIG. 3 is a hydraulic circuit diagram of a similar drive system using the valve device of this invention, and FIG. 4 is a hydraulic circuit diagram of a similar drive system for the valve device of this invention. FIG. 5 is a vertical sectional view showing one embodiment of the apparatus, and is a view taken along the line ■■-■■ in FIG. 4. 20: Check valve, 30: Pilot operated check valve,
40: Relief valve, 50: Solenoid switching valve, 54: Throttle.

Claims (1)

[Claims for Utility Model Registration] The pressurizing cylinder is connected to a pressurizing flow path between the pressurizing cylinder chamber of the single-acting cylinder piston device and the pump, and allows the discharge pressure oil of the pump to flow into the pressurizing cylinder chamber. a check valve that closes against the flow of pressurized oil flowing out from the chamber; and a check valve that is connected to a return flow path from the pressurized cylinder chamber to the tank and that controls the pressure inside the pressurized cylinder chamber when pressure is applied to the pylon 1. a pilot-operated check valve that drains oil into the tank; and a relief that is connected between the pump side of the pressurizing flow path and the tank side of the return flow path and maintaining the hydraulic pressure in the booster flow path at a set value. a valve; and a pilot port of the pilot-operated check valve and a vent port of the relief valve are selectively connected to a pressurized flow path from the pump and a return flow path to the tank, thereby controlling the single-acting cylinder piston device. an electromagnetic switching valve for switching between raising, lowering, and stopping operations of the piston, and the electromagnetic switching valve blocks the vent port of the IJ-F valve and blocks the pilot port of the pilot-operated check valve. a rising switching position that communicates the valve with a return flow path to the tank; and a stop neutral position that connects both the vent port of the linenof valve and the pilot port of the pilot-operated check valve with the return flow path to the tank; a lowering switching position that connects a pressurized flow path from the pump to a pilot port of the pilot-operated check valve and connects a vent port of the relief valve to a return flow path to the tank via a restriction; Furthermore, the opening degree of the throttle is such that sufficient back pressure is generated in the pressurizing flow path against the vent flow of the relief valve in the lowering switching position to generate a pilot pressure for operating the pilot-operated check valve. A valve device for driving a single-acting cylinder piston device for lifting heavy objects, characterized in that it has: