JPS61223304A - Pilot check valve equipped with decompression - Google Patents

Abstract

PURPOSE:To secure the stable pressure discharge action even in the hydraulic circuit in which a back pressure is generated onto the return side of a conduit connected to an inlet port and to reduce the dimension of a pilot piston by carrying out the pressure discharge action of a pilot check valve in utilization of a drain conduit. CONSTITUTION:The rod top-edge part of pilot piston 10 for opening/closing- operating a decompression poppet 6 accommodated into a main poppet 4 is formed in step difference form consisting of the small diameter part 13a and the large diameter part 13b. The small-diameter part 13a at the rod top-edge part is closely inserted in slidable ways into a cylindrical hole 7 in the main poppet 4, thus permitting the poppet 6 from bein opening/closing-operated from the top edge. When the poppet 6 is opened through a passage 14 formed at the rod top-edge part, the inside of the accommodation chamber 5 is allowed to communicate to the drain port 12 of the pilot piston 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a pilot check valve with decompression that has a pressure relief effect during backflow by pilot operation.

(Prior Art) FIG. 4 shows a conventional depressing pilot check valve DV. As shown in the figure, when the pressure oil flows in the forward direction from the inlet boat 32 side formed in the valve body 31 to the outlet boat 33 side in the pyrower 1-check valve DV with decompression,
It has a double poppet structure in which a smaller decompression poppet 36 is housed in the housing chamber 35 of the main poppet 34, which is normally provided to prevent the flow in the opposite direction. The pilot piston 37 is used to reverse the pressure oil (return to the tank).
When the poppet is opened by the main poppet 34, the decompression boppet 36 in the poppet 34 is opened before the main poppet 34 is opened.
The high-pressure oil inside is gradually released to the inlet side, suppressing sudden changes in pressure when the poppet is opened, and preventing impact. In the figure, 38 is a push spring that presses the de-compression poppet 36 and the main poppet 34 against the seat, 39 is a pilot port for the pilot screw 1-36, and 40 is a drain port.
□ (Means for solving the problem) By the way, in an actual hydraulic circuit incorporating the pilot check valve DV with decompression having the structure described above, the flow rate of pressure oil is In some cases, a throttle valve or the like is installed to control the For example, the third
As shown in the figure, in the operating circuit of the lift cylinder 15 in a forklift, a conduit 18 on the inlet boat side
An electromagnetic switching valve 17 with a throttle valve 16 is provided to control the elevation and speed. However, when such a throttle valve 16 exists, the lift cylinder 1
Switch the switching valve 17 to the lowering side to lower the tank T.
When electrical conduction occurs, back pressure is generated on the inlet port side (-next side), and this back pressure
When the poppet is opened by the main poppet 34, the internal pressure of the accommodation chamber 35 cannot be lowered below the pressure on the inlet port side, and as a result, a large pilot pressure is required to operate the pylon 1 to the piston 37. There was a difficulty in doing so.

Therefore, the technical problem to be solved by the present invention is to perform the depressurizing action of a pilot check valve with decompression using a drain pipe.

(Means for Solving the Problems) The technical means for solving the above problems are the rod tip of the pilot piston that opens and closes the main poppet and the depression povet concentrically housed within the main poppet. The part is formed into a stepped shape with a small diameter part and a large diameter part, and
The small diameter portion of the rod is slidably and tightly inserted into the cylindrical hole of the main poppet so as to be able to come into contact with the tip of the decompression poppet, and the rod also has the decompression poppet when the decompression poppet is pushed open. The passage that connects the storage chamber of the ression povet to the drain port of the pilot piston has been created in a unique way.

(Function) When pilot pressure is applied to the pilot piston, the tip of the small diameter part of the rod in the pilot piston first pushes the decompression pot to open it, so that the storage chamber of the decompression pot opens into the passage of the rod. It communicates with the drain port of the pilot piston through the chamber, and the high pressure oil in the storage chamber is gradually released. Then, when the pressure inside the storage chamber decreases, the large diameter portion of the rod pushes the main poppet to open it, and the high pressure oil on the outlet side flows to the inlet port side.

(Example) Hereinafter, an example of the present invention will be specifically described based on the drawings. Figure 1 shows a pilot check valve DV with decompression. In the figure, 1 is the valve body, and on the - side (right side in the figure) is the flow of high-pressure oil from the inlet port 2 side to the outlet port 3 side. A main poppet 4 is slidably and movably incorporated in the main poppet 4 to allow the flow of water and to prevent the reverse flow, and a decompression poppet for pressure handling is installed in a cylindrical housing chamber 5 formed in the main poppet 4. 6 is accommodated.

In addition, a small-diameter cylindrical hole 7 that communicates with the storage chamber 5 is formed on one side (left side in the figure) of the main poppet 4 concentrically with the storage chamber 5, and on the outer periphery, the outlet boat 3 and the storage chamber 5 are connected. Small hole 8
is formed.

The decompression poppet 6 is always a push spring 9.
The main poppet 4 is pressed against the seat so as to cut off the communication between the accommodation chamber 5 and the cylinder hole 7, and the main poppet 4 is pressed against the seat so as to cut off the communication between the outlet port 3 and the inlet port 2 via the compression poppet 6. is being pressed against.

On the other hand, a pilot piston 10 for poppet operation is slidably built into the other side of the valve body 1 (on the left side in the figure) in a state where it faces concentrically with both poppets 4.6. A pilot boat 11 is formed on one side (left side in the figure), and a drain port 12 is formed on the other side. Also, pilot piston 1
The rod 13 extends slidably and closely through the wall 1a between the drain port 12 and the inlet port 2 to the poppet side, and its tip side is formed to have a small diameter.

That is, the rod 13 of the pilot piston 10 is formed in two stages, including a small diameter part 13a and a large diameter part 13b, and the small diameter part 13a is slidably and tightly inserted into the cylindrical hole 7 of the main poppet 4. The decompression poppet 6 can be pushed by the end face of the small diameter part 13b, and the main poppet 4 can be pushed by the stepped end face of the large diameter part 13b. Further, a through hole 14 is formed in the rod 13 in the axial direction, and one end of the through hole 14 communicates with the cylindrical hole 7 of the main poppet 4, and the other end communicates with the drain port 12.

Note that a mouth-shaped metal fitting 14a is fixed to the tip of the rod 13 to prevent the through hole 14 from closing when it comes into contact with the decompression boppet 6.

FIG. 3 illustrates a case where the pilot check valve DV with decompression configured as described above is incorporated into the operating circuit of the lift cylinder 15 of a forklift. As shown in the figure, the pilot check valve DV with decompression is connected to a lift cylinder 15,
It is arranged in the piping with an electromagnetic switching valve 17 with a throttle valve 16 that controls the supply and discharge of pressure oil to and from the lift cylinder 15, and the inlet port 2 is connected to the conduit 18 on the side of the electromagnetic switching valve 17, and the outlet The boat 3 is connected to the pipe line 19 on the lift cylinder 15 side.
is connected to. And pilot check valve DV
The pilot boat 11 is connected to a pump P1 for generating pilot pressure via a pilot line 20, and the drain port 12 is communicated with a tank T via a drain line 21.

In addition, in FIG. 3, P is a hydraulic pump for driving the lift cylinder, and 22 and 23 are relief valves.

The present embodiment is constructed as described above, and as shown in FIG. 3, when the electromagnetic switching valve 17 is held in the neutral position, the pilot line 2o is cut off, so that the pilot line 2o with decompression Check valve DV is the first
It is maintained in the state shown in the figure.

In this state, when the electromagnetic switching valve 17 is switched to the 1-stroke side (a), the high pressure oil discharged from the hydraulic pump P passes through the electromagnetic switching valve 17 to the pilot check valve DV.
At the same time, the main poppet 4 is pushed open together with the decompression boppet 6 against the push spring 9.

It flows to the outlet port 3 side, and from there flows into the lift cylinder 15 through the pipe line 19, causing the lift cylinder 15 to rise.

Therefore, when the electromagnetic switching valve 17 is switched to the lowering side (b) in order to lower the lift cylinder 15, the pilot pipe 20 is communicated, and the pilot pressure from the pump P1 acts on the pilot piston 10. In order to push the decompression bobbet 6, as shown in FIG. is communicated. Therefore, the high pressure oil in the storage chamber 5 is discharged from the cylinder hole 7 through the through hole 14 of the rod 13 to the drain port 12 side of the pilot piston 10, and the pressure in the storage chamber 5 is reduced.

9 Next, the stepped end surface of the large diameter portion 13b of the rod 13 comes into contact with the main poppet 4, and pushes it together with the decompression poppet 6 against the push spring 9, but at this time, the inside of the storage chamber 5 Since the pressure is decreasing, the main poppet 4 is opened with a small pilot pressure. As a result, exit boat 3
The high-pressure oil on the outlet side returns to the tank T, and the lift cylinder 15 is lowered.

Although this embodiment has been described as a case in which the pilot check valve with decompression is incorporated into the operating circuit of the lift cylinder 15 for a forklift, its application is not limited to this. It is effective if the circuit has a valve such as a throttle valve inserted on the return side of the pipe line that regulates the flow rate.

(Effects of the Invention) As described in detail above, according to the pilot check valve with decompression of the present invention, by communicating the storage chamber of the decompression boppet with the drain pipe during pressure handling, the inside of the storage chamber is By lowering the pressure, the main poppet can be opened by the pilot piston with a small operating force, which makes it possible to downsize the pilot piston and provide a stable pressure relief effect.

The pilot check valve with decompression of the present invention is particularly effective when incorporated into a hydraulic circuit in which back pressure is generated on the return side of a pipeline connected to an inlet boat.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the decompression valve pilot check valve according to the present invention.
The figure is also a sectional view showing the opening operation by the pilot piston, Figure 3 is a hydraulic circuit diagram of an example in which a decompression-equipped piping check valve is incorporated into the forklift cylinder 71 to cylinder operating circuit, and Figure 4 is a conventional hydraulic circuit diagram. FIG. 2 is a sectional view showing a pilot check valve with decompression. 1... Valve body 2... Inlet boat 3...
Exit boat 4...Main 4C bet 5...Containment room 6...Decombresi'nbopet

Claims (1)

[Claims] The tip of a rod of a pilot piston that opens and closes a main poppet and a decompression poppet concentrically housed in a housing chamber formed in the main poppet is formed into a stepped shape with a small diameter part and a large diameter part, and the rod The small diameter part of the rod is slidably and tightly inserted into the cylindrical hole of the main poppet so as to be able to abut against the tip of the decompression poppet, and the rod is also provided with a pilot piston to open the accommodation chamber when the decompression poppet is pushed open. A pilot check valve with decompression that has a through hole that communicates with the drain port.