JPS58160603A - Fluid control valve - Google Patents

Abstract

PURPOSE:To improve operability and reduce loss of energy by providing, in a multiple pressure control valve, a shut off valve which works upon sensing any pressure difference in a bypass circuit. CONSTITUTION:In case of operating a lift upward by pulling out a spool 2', since bypass passages 7a and 7b are cut from each other by means of the spool 2', the pressure oil in the bypass passage 7a flows through a communicating passage 24 to a spool side chamber 25 of a shut off valve 21, and moves a spool to cut circuits 19 and 22 from each other, therefore, a main piston 15 communicates with only a high pressure pilot relief valve 20. The pressure oil from an inflow port 6 flows to the spool 2' through supply passages 42, 43 via check valves 12, 12' and flows into a cylinder port. Further, in case of operating a lift downward with the spool 2' pushed in, the bypass passages 7a and 7b are not cut from each other and, since the bypass passage 7a is left opened, the pump pressure turns in an unload state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-pressure control pulp that is equipped with a plurality of flow rate adjustment switching valves to control fluid pressure in order to operate equipment such as a forklift.

In dual-pressure control pulp, which is often used in industrial vehicles such as forklifts and pel loaders, the relief pressure is automatically set to a high level only when the hydraulic system that requires high pressure is activated in order to raise and lower the cargo. While other hydraulic systems that do not require high pressure are operated, it is necessary to automatically set the leaf pressure to a low level so that it does not adversely affect the life of hydraulic parts. It is.

In order to fully satisfy these demands, the present invention provides low pressure jJ9-7 when lifting cargo by switching between high and low pressure operations.
High pressure IJ with the valve inoperative and set at a higher relief pressure Until the pilot pressure reaches the set pressure of the IJ-7 valve, the relief pressure is automatically increased without operating the pilot operated relief valve, and a large lifting force is generated. The purpose of the present invention is to provide a multi-pressure controlled pulp that can be used for high performance, and can be relieved at low pressures, has a flow rate adjustment function, significantly improves operability, and has low energy loss.

The present invention includes a plurality of flow rate adjustment switching valves or spools in a fluid passage communicating with a pump at one end and a tank at the other end;
a pilot-operated relief valve displaceable, a plurality of output ports controlled by the spools, and a plurality of output ports controlled by the spools; a bypass passage arranged so that communication with the tank is cut off, and a high-pressure relief pilot valve and a low-pressure relief pilot valve are provided in a pilot circuit in which the pilot-operated relief valve is located. In a multi-pulp system in which each of the discharge passages is connected to the tank at all times, the pressure difference between the upstream side and the downstream side is created in the pilot circuit that communicates the high pressure relief pilot valve and the low pressure relief pilot valve. For fluid control, comprising a shut-off valve that is sensed and activated, and configured such that the pilot circuit opens one of the sieve pools in a neutral position and closes it when the valve is operated to an operating position that requires high pressure. It's pulp.

In particular, one of the important features of the present invention is that in multi-pulp pulp with a bypass circuit that bypasses the main capacity, the relief pilot line is detected by sensing the pressure difference between the upstream and downstream sides of the bypass circuit that is cut by the spool. A high-pressure pilot relief valve is provided on the upstream side of the pilot passage of this shut-off valve, and a low-pressure pilot relief valve is provided on the downstream side of the shut-off valve. Another feature of the present invention is that in multiple pulp, the pilot passage is branched from the pilot passage leading to the low-pressure pilot relief valve downstream of the shutoff valve, and is connected to the downstream side of the flow rate adjustment throttle valve of the switching valve via the check valve. It has a communicating circuit, and uses the differential pressure caused by the pressure drop of the flow rate regulating throttle valve to operate the pilot-operated relief valve, that is, the main piston of the main cleaner 7, to bleed off excess oil.

Furthermore, the feature of the present invention is that in the □ bypass section of the switching valve downstream from the second station, the downstream bypass section is closed by the operation of the spoo, and the spool on the upstream side (the series) is activated. By providing a throttle hole in the bypass part so that when the bypass part is closed, the pressure in the second and subsequent bypass parts is not trapped, that is, the pressure in the second and subsequent bypass parts is trapped. When the next series of operations is performed, the oil in the spring chamber of the shaft-off valve is trapped and does not operate, so that it has a flow rate adjustment function, and if high pressure is required, the high pressure is 99-7L, otherwise it is 99-7L. The purpose is to convert 9jl-7 at low pressure into 99-fuparv.

The present invention will be described with reference to the drawings with reference to the drawings, in which a high-pressure pilot relief valve and a pilot-operated relief valve, for example, an inlet section 1 with a main piston 15, a lift block section 2 with a spool τ, and a spool 3' with a high-pressure pilot relief valve. The tilt pump section 3 and the end section 4 where the low-pressure pilot relief valve n and the shutoff valve 21 are located are connected under a delayed state through a fluid passage connected to the pump and tank, a pilot circuit, and a bypass passage to form multiple pulp. be.

An inlet 6 for pressurized oil supplied from the pump 5 is connected to a flow path 9 and a high pressure flow path 11 that communicate with a #l opening 10 that is connected to a tank.
, and a bypass passage 7. Normally, a main piston 15 having an orifice 16 opened at the tip of an inlet 611 is arranged to block the inlet 6 and the flow passage 9, and is biased by a spring 17. Also, Mukuro main piston 15
A high pressure pilot relief valve is installed in the nookune chamber 18 formed on the back of the low pressure! J9-7 Bengen is circuit 1
8' and 19 are connected in parallel, and the high pressure valves (99-) on the upstream side of the fluid passage are connected to the circuit 11,
Discharge path 39. From the flow path 9 to the outlet 1G, the low pressure pilot 99-7 valve located downstream of the fluid path is labeled as circuit 19.
, 22 discharge passage 40.8 is always in communication with the outlet 10,
It constitutes a pilot circuit.

The inlet 6 communicates with the high pressure passage 11 of the lift block section 2 and the tilt block section 3, and is connected to the check valves 12, 1τ.
, to the spool 2' via the supply passages 42 and 43, to the spool 3 via the check valves 13 and 14, and to the spool 3 via the supply passages O and 34.
', and by switching the spools, the cylinder ports are communicated with each other.

The bypass passage 7 has a spool l serving as a cylinder switching valve.
, 3' are in a neutral state, C is bifurcated so that the pressure oil flowing in from the flow 4 port 6 is bypassed to the discharge path 8.

The bypass passage 7 of the above-mentioned 7 block part 2 is defined as the upstream side where the spool 2 is moved (2) is the bypass passage 7a + the downstream side is the bypass passage 2, and the bypass passage 7 of the tilt block part 3 is The side bypass passage 7c is the downstream side, and the downstream side is 7d.

The low pressure bail relief valve n communicates with the spring chamber 18 of the main piston 15 via the shaft off valve 21 which opens and closes with the movement of the spool, but the spool@chamber 25 of this shaft off valve 21 is connected to the communication passage 24. The bypass passage 7aε of the lift block part 2 is in communication, and the spring side chamber n is a communication passage and the bypass passage 7c (=in communication) of the tilt block part 3.And normally, the main piston 15
spring chamber 18 circuit 19 and low pressure pilot relief valve 2
The spool of the shaft-off valve 21 moves against the spring array when the oil pressure in the communication passage is higher than that in the communication passage. The configuration is such that communication between the circuit 19 and n is cut off.

The circuit 22 branches into two branches, one of which is low voltage] (Iro?)
9 Leaf valve n The other side communicates with the passage 4, and the skeleton passage 29 further branches into two passages 31 and 32, which communicate with the supply passage blades 34 of the tilt block part 3. ) It is communicated through a check valve nod to prevent backflow when the left gyrus is activated.

The high pressure passage 11 of the tilt block section 3 communicates with the supply passages O and 34 via the check valves 13 and 14, and pressurized oil is communicated from the bore of the spool 3' to the cylinder port. The strokes of these check valves 13 and 14 are regulated by stoppers 35 and 36 with stroke adjustment screws.
Since the check valve is configured to be throttled at 37 and 38, it functions as a throttle valve with a check valve.

[e) A throttle hole 41 is provided in the spool of the tilt block section 3, and the bypass passages 7C and 7d communicate with each other through the throttle hole 41 when the spool is pulled out. The throttle hole is not limited to the spool, but the body of the tilt block portion 3 may be provided with a throttle hole that communicates with the discharge passage 8.

In the figure, they are springs 44, 45, and 46.

Therefore, when the spool τ of the lift block section 2 is pulled out to perform a lift raising operation, the bypass passages 7a and 7b are cut off by the spool τ, so that the pressure oil in the bypass passage 7a passes through the communication passage to the shutoff valve 21. Since the spool is moved to the spool side chamber 5 and the circuits 19 and n are disconnected, the main piston 15 is in communication only with the high pressure pilot valve 99 and operates as a high pressure relief.

The pressure oil from the inlet 6 then passes through the check valves 12 and 12' from the high pressure passage 11m, reaches the spool τ from the supply passage 42, 43, and flows into the cylinder boat.

Further, when the spool 2' is pushed in to lower the lift, the bypass passages 7a and 1 are not cut off, and the bypass passage 7 remains open, so that the pump pressure is in an unloaded state.

On the other hand, when the spool 3' of the tailed block section 3 is pulled out or pushed in to perform a tilt operation, the bypass passages 7c and 7d are cut by the spool 3', and the bypass passage 7a is cut off by the spool 3'.
The pressure oils 7c and 7c communicate with the spool side chamber of the shutoff valve 21 and the spring restraint 27 through communication passages 26, respectively. In this case, since the pressure oil in the bypass passages 7m and 7c is at the same pressure, the spool of the shutoff valve 21 remains biased by the spring and does not move, and the circuits 19 and 22 are in communication, so the low pressure pilot relief is turned to the left. As a result, the main piston 15 operates as a low-pressure relief whose maximum pressure is the set pressure of the left-hand low-pressure pilot relief.

For example, when the spool is pulled out, the pressure oil flowing into the high pressure flow path 11 is transferred from the high pressure flow path 11b to the check valve 1.
3's Cheno 7? -) It passes through 37, reaches the spool, and flows to the cylinder boat. Check Jtv-)
The inside of the supply passage from 37 to the spool 3' is constricted and the pressure drops, and the inside of the spring chamber 18 of the main piston 15, which communicates with this supply passage vane via passages 31, 29, and circuits n and 19, also increases. The pressure becomes the same as the dropped pressure.

At this time, the main piston 15 is biased by the spring 17, but the pressure difference between the front and rear of the main piston automatically adjusts the main piston 15 once, and excess oil bleeds off to the flow path 9 and the outlet lO.

In other words, the main piston 15 is adjusted so that the pressure difference between the pressure oil before and after 37 is equal to the pressure of the spring 17.
The cylinder automatically appears and drains excess oil into the tank using the bleed-off pressure of the cylinder load indenter spring pressure. In this case, when the opening degree of the seat q of the chino becomes large, the bleed-off amount also becomes large, and when the degree of opening of the seat q becomes small, the bleed-off amount also becomes small.

For example, when the pressure of spring 17 is set to ld inn, ? ) The opening degree of the main piston 15 is automatically adjusted to bleed off excess oil so that a flow rate such that the pressure drop at 37 is 5.5 cm regardless of the size of the opening degree is sent to the high pressure flow path 11b. It is.

Since the main piston 15 also has a flow rate control function in this way, it is extremely efficient compared to simply relieving pressure oil using a relief set pressure during high and low pressure control.

- When the spool τ is pulled out and spooled simultaneously in the lift block section 2, the bypass passage 7a and the spool are disconnected, so the operation is the same as when the spool τ is pulled out alone.

Pushing in the spool τ and operating the spool 3' simultaneously is the same as in the case of a single operation of the spool 3', since the bypass passages 7c and 7d are cut off.

If the spool τ is then pulled out while performing the spool completion operation, first the bypass passages 7c and 7d are cut off, and then the bypass passages 7a and 7b are cut off.

At this time, the pressure oil in the bypass passages 7b and 7c flows out from the throttle hole 41 provided in the spool 3', and the pressure becomes lower than that in the bypass passage 7a. Cut the main piston 1
5 acts as a high pressure relief.

The examples in FIGS. 8 to 14 are examples in which a 99-f valve for high pressure and a relief valve for low pressure are used together, and the relief for high pressure includes the main piston 15s, the piston spring chamber 181, the spring 171, and the high pressure pilot. The relief valve 20 and the low pressure relief are the main piston 152. The front in-piston 1 consists of a piston spring chamber 2, a spring 17z and a low pressure pilot relief valve 23.
The main piston 152 as a relief valve only for low pressure is placed separately between the high pressure passage 11 and the discharge passage 8, and the spring chamber 181 of the main piston 151 is connected to the high pressure pilot tree 7 valve. The spring chamber 182 of the main piston 152 communicates with the left-hand low pressure pilot relief via the shutoff valve 21. Each main piston 151 # 152 has an orifice 141 e 142 in the piston head, and a flow path 9 .
Spring 171t 1 to block the flow of pressure oil to
Although the main piston 152 is energized by the main piston 72, the main piston 152 also has a flow rate control function as in the previous embodiment, and is functionally operated.

In order to open and close the pilot circuit of the relief valve, it is sufficient to sense the pressure difference in the pressure passage and operate the shutoff valve, and the circuit for operating the shutoff valve is located in the excess wall of the valve block. This can be easily achieved by drilling holes. Furthermore, since all the control equipment can be incorporated into the end section, it is convenient to use completely standard products for the inlet section.

According to the present invention, when high pressure is required, the relief pressure of the circuit is automatically set high, and at other times the circuit is relieved at low pressure, improving operability and reducing energy loss.
It can be made into a pulp for fluid control that also increases the durability of parts.
In practical terms, it has the effect of fire.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a cutaway plan view, FIG. 2 is a vertical sectional view taken along the line 1-1 in FIG. ! (Longitudinal cross-sectional view of 2, Fig. 4 is an A end view of Fig. 1, Fig. 5 is a B end view of Fig. 1, 611
1 is a C end view of FIG. The cross-sectional view in Figure 8 *-** and Figure 11 are! FIG. 12 is the E end view of FIG. 8, FIG. 13 is the F end view of FIG. 8, and FIG. 1114 is the 70-sheet of FIG. 8. 1... Inlet part, 2... Lift block part, 3
... Tilt block part, 4... End part, 5...
・Pump, 6... Inlet, 7... Bypass passage, 8
...Exhaust channel, 9-...Flow path, lO... Outlet, 11
...High pressure flow path, 12...Check valve, 13, 14
... Check valve, 15 ... Main piston, 16
...Orifice, 17.../<4,18...C rice chamber, 1g', 19...Circuit, Ka...High pressure pilot relief valve, 21...Shutoff valve, 4...・Circuit, O...Low pressure pipe four-way valve, Sae...Communication path, 25...Spool side chamber, 26...Communication path, I...
- Spring side chamber, 4... Spring, 29... Passage, 30...
・Check valve, s1*32...Passage, wing, 34...
Supply passage, holder, 36... stopper, 37, 38...
・Check valve sea), 39.40...Discharge path, 41・
... Throttle hole, 42, 43... Supply passage. 22 □Figure 3-23-

Claims (1)

[Claims] 1. A pump at one end and a tank at the other end; a plurality of flow rate adjustment switching valves or spools and a pilot-operated relief valve are movably provided in the communicating fluid passage; A plurality of outlet ports are controlled by the spools, and communication from the pump to the tank is severed when any one of the spools is operated beyond the neutral position to the operating position. ; a high pressure relief pilot valve and a low pressure relief pilot valve are provided in the pilot circuit in which the pilot operated relief valve is located, and each of these discharge passages is constantly communicated with the tank; In such a multiple valve, a pressure difference between the upstream side and the downstream side is sensed and activated in a pilot circuit that communicates the high pressure relief pilot valve and the low pressure 9-7 pilot valve. Pulp for fluid control, characterized in that the pilot circuit is configured to open one of the spools at a neutral position and close when operated at an operating position ζ that requires high pressure. The valve consists of spools that slide under pressure from a spring, and when one of the spools is placed in the operating position, the pilot circuit is cut off and communication with the low pressure pilot valve is established. The valve according to claim 1, which disconnects the valve. (v) The front-distributed Yat-off valve is provided in a position where a high-pressure pilot relief valve is provided on the upstream side of the pilot circuit and a low-pressure pilot relief valve is provided on the downstream side of the pilot circuit, as described in claim 1 or s2. pulp. 4. The pilot-operated relief valve is a freely sliding hollow piston biased by a spring, and is moved by differential pressure with an orifice communicating with the hollow portion. 5. The spools are p-rads that are operated respectively when high pressure and low pressure are required, and are arranged in series and intersectingly in the fluid passage, respectively. The spool is composed of a lift spool and a tilt spool, and when the tilt spool is activated, the downstream side of the pilot circuit is closed, and the lift spool is activated to close the bypass portion. 2. The pilot circuit is branched from the passage leading to the low pressure relief valve. The pulp according to claim 5 or 6, which has a passageway and communicates with the pump pressure supply passageway of the tilt spool via a check valve. It has a circuit that branches from the pilot passage and communicates with the downstream side of the flow rate adjustment throttle valve for switching via a check valve, and uses the differential pressure caused by the pressure drop of the axillary flow rate** throttle valve to perform the pilot operation. The pulp according to claim 117, wherein excess oil can be bleed off by operating a relief valve.9 The bypass passage is provided with multiple flow rate adjustment switching valves. Then, the downstream switching valve is used as a flow rate regulating throttle valve, and if the pressure in the second and subsequent series is trapped, the fluid in the shut-off valve chamber will be trapped when the next series is operated. The pulp according to claim 7 or 8, wherein the pulp is configured to be able to be used in a fluid passageway that communicates with a pump at one end and a tank at the other end. A valve or spool and a pilot-operated relief valve are displaceably provided, a plurality of output boats are controlled by the spool, and any particular one of the spools is operated beyond a neutral position to an operating position. a bypass passage arranged so that communication from the pump to the tank is cut off when In the case of multi-pulp pulp, which is equipped with a low-pressure dedicated valve (a pilot-operated leaf valve) and a low-pressure pilot relief valve, and which is connected to the tank so that each of these discharge passages is always connected to the tank, Equipped with a shutoff valve that operates by sensing the pressure difference between the upstream side and the downstream side of the spool, the shutoff valve shuts off the low pressure dedicated pilot operation circuit, stops the operation of the low pressure relief, and can be operated only as a high pressure relief. 411111 Pulp for fluid control that has the following properties. 1t The front-distributed Jagd-off valve consists of spools that slide under pressure from a spring, and when one of the spools is placed in the operating position, the pilot circuit is cut off and the pressure is low. The pulp according to claim 10, which disconnects from the valve. 12. The low-pressure dedicated pilot-operated relief valve is composed of a freely sliding hollow piston that is biased by a spring and moves by differential pressure, and a low-pressure pilot relief valve that communicates with this hollow part, and has an end portion. The pulp according to claim 111110 or claim 11, which is provided in the following. 1. The high-pressure dedicated pilot-operated relief valve is a hollow piston that is biased by a spring and moves by differential pressure, and is composed of a freely sliding hollow piston and a high-pressure pilot relief valve that communicates with this hollow part, and is provided in the inlet part. The pulp according to claim II II 1G, @11 or 12, which is 14. The low-pressure dedicated pilot circuit has a bypass passage separated from the passage leading to the low-pressure pilot relief valve, and is equipped with a check valve to control the low-pressure pilot operation 9.
9-7 Valve 9-7 communicates with the pump pressure supply passage so that excess oil in the pump can be bled off to the tank by the differential pressure before and after the valve.SOL! The pulp according to item 1 or item 13. 15. In order to have the function of a flow rate adjustment throttle valve for switching the low-pressure dedicated pilot circuit branched from the pilot circuit via a check valve, a flow rate adjustment throttle is provided with a stopper with a stroke adjustment screw on the outside of the throttle valve. The pulp according to claim 14, which is equipped with a valve.