JPH02482Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an improvement of a pilot check valve, and relates to a differential pilot check valve that prevents the so-called water hammer phenomenon that occurs when the check valve opens.

In conventional pilot check valves, when the check valve is opened, the load pressure acting on the back side is communicated to the low pressure side, and then the check valve is opened.In order to smoothly release the load pressure, the check valve is equipped with a poppet valve. However, there is a slight time delay between the opening of the poppet valve and the opening of the check valve, and if the load pressure is high, a water hammer phenomenon may occur, causing oil leakage from piping, etc. due to impact, and This caused the valve to malfunction. (Jikko 53-
Publication No. 40746, Publication No. 34258, Publication No. 40746, Publication No. 34258, Publication No. 40746
(Publication No. 34259) This invention proposes a pilot check valve that prevents the water hammer phenomenon described above.

Summary of the device This device consists of a central valve hole and stepped holes with a diameter slightly larger than the valve hole on both sides of the central valve hole. A valve body having an oil passage communicating between the spool and the secondary port, a sleeve hole into which the small diameter land of the spool fits and slides in the axial direction, a through hole into which the spool rod fits and slides, and a through hole into which the spool rod fits and slides, and a secondary port in the circumferential direction. A sleeve with multiple communication holes to the side oil passage and fitted and fixed into one stepped hole of the valve body, a small diameter seat hole at the tip, and multiple holes communicating with the secondary oil passage on the circumference. A check valve that has a cone valve that is pressed into a small diameter seat hole by a spring and is slidably inserted into the other stepped hole of the valve body to close the oil passage. , It has a large diameter land that fits and slides into the central valve hole and a small diameter land that fits and slides into the sleeve hole of the sleeve to block the oil passage, and one end is stored in the end hole of the sleeve to limit stroke. The valve is pressed by a spring through a piston-shaped stopper, and when in neutral, the other end surface consists of a spool that corresponds to a cone valve, and when the spool is moved by pilot pressure supply, the load pressure blocked by the check valve is released. When the check valve is opened, the oil passage on the sleeve side is opened, and conversely, when the load pressure blocked by the small diameter land is released, the oil passage on the sleeve side is first opened, and then the check valve is opened. This is a pilot check valve characterized by comprising:

Disclosure Based on Drawings of the Invention The invention will be described in detail below based on the drawings of the embodiment. 1st
The figure is a longitudinal sectional view of the pilot check valve according to this invention.

Configuration The valve body 1 has a central valve hole 2 and stepped holes 3 and 4 with a diameter slightly larger than the valve holes on both sides of the central valve hole 2, and ports A, B, ports A',
B' is open, and oil passages 5 and 6 communicate between the central valve hole 2 and ports A and B, oil passages 7 that communicate between stepped holes 3 and 4 and ports A' and B', 8 is provided.

One stepped hole 3 has a sleeve hole 11 into which a small diameter land portion 42 of a spool 40 fits and slides in the axial direction.
A sleeve 10 having a plurality of communicating holes 12 to the oil passage 8 is inserted into the through hole in which the spool rod is inserted and slid, and is fixed by an end cover 9 into which a sleeve 10 is fitted.

In the other stepped hole 4, a cylindrical check valve 20 having a small-diameter seat hole 21 on the end face on the side of the central valve hole 2 and a plurality of communication holes 22 communicating with the oil passage 7 on the circumference is slidably attached. The cone valve 30 is inserted into the inner hole 23, and the tip 31 of the cone valve 30 protrudes from the small diameter seat hole 21 toward the center valve hole 2 side.

This check valve 20 has a spring 24 that holds the cone valve 30 in the spring seat hole of the end cover 9, so that the tip end 31 of the cone valve 30 is attached to the small diameter seat hole.
1 and is pressed toward the center, and abuts against the valve seat 25 fitted into the innermost end of the stepped hole 4 to close the space between the oil passage 5 and the oil passage 7.

Note that the through hole 26 of the valve seat 25 is connected to the spool 4.
The land portion 41 is configured to have a smaller diameter than the large diameter land portion 41 of 0.

The spool 40 is comprised of a bulging rod with a large diameter land portion 41 that fits and slides into the central valve hole 2 and a small diameter land portion 42 that fits and slides into the sleeve hole 11 mentioned above.

In the figure, the left end of the spool 40 is pressed by a spring 14 held in the spring seat hole of the end cover 9 via a piston-shaped stopper 13 housed in the end hole of the sleeve 10, and the right end surface of the rod portion at the other end is pressed. However, since the piston-shaped stopper 13 is restricted from going to the right in the figure by the stepped part of the end hole of the sleeve 10, for example, when it is released after moving to the left in the figure, the right end surface is moved to the cone. It is not brought into contact with the valve 30.

That is, when the directional control valve 50 is in the neutral position as shown in FIG. The design is such that there is a gap between the two.

This configuration is such that when the spool 40 is held in the neutral position, the cone valve 30 closes the small diameter seat hole 21 and retains the pressure fluid in the oil path 7.

Operation In the above configuration, the directional control valve 50 is connected to ports A and B, and the cylinder 51 is connected to ports A' and B'.

When the directional control valve 50 is switched to the position, pressure fluid, ie, pilot pressure, is supplied to port B, and the port A side is connected to the reservoir tank.

The pressure applied to the B port is applied to the large diameter land portion 41 and the small diameter land portion 4 of the spool 40 via the oil path 6.
2, but due to the difference in pressure receiving area, spool 4
0 to the right, and first insert the cone valve 3 at the tip of the rod.
0 to the right, and the small diameter seat hole 2 of the check valve 20.
1 is opened and the microfluid is discharged from the oil passage 7 to the oil passage 5.

Immediately thereafter, the tip of the rod of the spool comes into contact with the end face of the check valve 20 and moves to the right to open the gap between the tapered portion of the check valve 20 and the valve seat 25.

As a result, the load pressure of the oil passage 7 is changed from the oil passage 5 to the A
port and then through the directional valve 50 and back into the reservoir tank.

In the case of a conventional valve that has check valves at both ends of the spool, when pressure is applied to the B port, the check valve on the left side opens at the same time as the spool moves to the right, and the pilot pressure is transferred from oil path 6 to oil path 8 to B'. Since the rod side of the cylinder 51 is pressurized via the port, the pressure in the oil passage 7 rises above the load pressure, causing a sudden pressure change when the check valve 20 opens, causing a water hammer phenomenon. do.

However, in this invention, when the spool 40 moves to the right to open the check valve 20 and release the load pressure in the oil passage 7, the small diameter land portion of the spool 40
2 overlaps with the sleeve hole 11,
Since the oil passages 6, 8, and cylinder 51 are closed, only the load pressure held by the check valve 20 is released from the pressure in the oil passage 7, so water hammer phenomenon occurs even when the check valve 20 is opened. does not occur.

Furthermore, after releasing the pressure in the oil passage 7, the spool small-diameter land portion 42 is removed from the sleeve hole 11, and the oil passage 6, oil passage 8, and the rod side of the cylinder 51 are communicated with each other, and the rod of the cylinder starts to operate on the contraction side. However, after reaching the predetermined stroke, the directional control valve 50 is returned to the neutral position.

Then, all the pressure in the A and B ports is discharged to the reservoir tank. The spool 40 is therefore pushed back by the spring 24 of the cone valve 30 and returned to the position shown in FIG.

At this time, the stopper 13 is pressed against the stepped portion of the end hole of the sleeve 10 by the spring 14, and the spool 40 is pushed back by the spring 24 of the cone valve 30.
comes into contact with the stopper 13 and stops.

Next, when the directional control valve 50 is switched to the opposite position, the pilot pressure is supplied to the A port and passes through the oil path 5 to the large diameter land portion 41 of the spool.
The check valve 20 is pressurized.

Here, the diameter of the large diameter land portion 41 is the same as that of the valve seat 2.
5, and the spring 14 on the left side of the figure is designed to be weaker than the spring 24 on the right side of the figure. The cylinder 51 is removed from the sleeve hole 11, and the oil passage 6 and the oil passage 8 are communicated with each other, and the pressure on the rod side of the cylinder 51 is released to the reservoir tank.

Thereafter, since the check valve 20 opens, the cylinder begins to smoothly move toward the rod extension side without receiving any shock.

When the stroke process is completed, the directional valve 50
When the spool 40 is returned to the neutral position and the fluid in the oil passages 5 and 6 is returned to the reservoir tank, the spool 40 is returned to the neutral position (the illustrated position) by the spring 14.

That is, after the spool 40 moves to the left in the figure,
When the spool 40 is released and returns to the neutral position, the left end of the spool 40 is pressed by the spring 14 via the stopper 13 and moves to the left until it stops, and the right end of the spool 40 is directed toward the check valve 20 with a gap, and is inserted into the sleeve hole 11. A small diameter land portion 42 is located within to hold the spool 40 in a neutral position.

Effects of the invention As described above, when the pressure oil in the oil passage 7 is released and the cylinder rod starts to move to the contraction side, first the check valve 20 is opened, and then the oil passage 6 and the oil passage 8 are made to communicate with each other. When starting the cylinder rod extension side operation, first, the oil passage 8 and the oil passage 6 are made to communicate with each other, and then the check valve 20 is opened.

In short, the pilot check valve of this invention is configured to supply pressure to the upstream side after releasing pressure on the downstream side, so it prevents the water hammer phenomenon that occurs due to sudden pressure changes when switching the valve. Hydraulic shock can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a pilot check valve according to this invention. 1... Valve body, 2... Central valve hole, 3, 4... Stepped hole, 5, 6, 7, 8... Oil passage, 9, 9'... End cover, 10... Sleeve, 11... ... Sleeve hole, 12, 22 ... Communication hole, 13 ... Stopper, 14, 24 ... Spring, 20 ... Check valve,
21...Small diameter seat hole, 26...Through hole, 30...
... Cone valve, 31 ... Tip, 40 ... Spool, 41 ... Large diameter land, 42 ... Small diameter land, 50 ... Direction switching valve, 51 ... Cylinder.

Claims (1)

[Scope of Claim for Utility Model Registration] A central valve hole and stepped holes with a slightly larger diameter than the valve holes are drilled in the center longitudinal direction on both sides, and an oil passage communicating between the central valve hole and the primary port and each stepped hole are arranged. The valve body has an oil passage that communicates between the hole and the secondary port, a sleeve hole into which the small diameter land of the spool fits and slides in the axial direction, a through hole into which the spool rod fits and slides, and a secondary port in the circumferential direction. A sleeve that has multiple communication holes between the ports and side oil passages and is fitted and fixed into one stepped hole of the valve body, a small diameter seat hole at the tip, and communication with the secondary oil passage on the circumference. A check valve that has multiple communication holes, has a built-in cone valve that is pressed against a small-diameter seat hole by a spring, and is slidably inserted into the other stepped hole of the valve body to close the oil passage. It has a large diameter land that fits and slides into the central valve hole, and a small diameter land that fits and slides into the sleeve hole of the sleeve to block the oil passage, and one end is housed in the end hole of the sleeve and the stroke is controlled. It is pressed by a spring through a restricted piston-like stopper, and when in neutral, it consists of a spool whose other end face corresponds to a cone valve, and when the spool is moved by pilot pressure supply, the load pressure blocked by the check valve is removed. When opening, first open the check valve and then open the oil passage on the sleeve side; conversely, when releasing the load pressure blocked by the small diameter land, first open the oil passage on the sleeve side and then open the check valve. A pilot check valve comprising: