JPS6155476A - Lift valve - Google Patents

Abstract

PURPOSE:To improve a sealing effect, for instance, prevent a seal firg from being detached and damaged, by providing an extrusion preventive ring, which prevents the seal ring from being extruded outside a valve seat groobe by the pressure of fluid, and setting hardness of extrusion preventive ring to a specified condition. CONSTITUTION:A relief valve 9, forming in its valve seat part 3 an annular valve seat groove 4, is closed by adapting a valve surface 6 of a valve unit 2 to a seal ring 5 supported to said valve seat groove 4. Here the valve 9 juxtaposes with the seal ring 5 an extrusion preventive ring 7, which prevents the seal ring 5 from being extruded outside the valve seat groove 4 by the pressure of oil, in the down side of an oil path of the seal ring 5, fitting the ring 7 to be supported in the valve seat groove 4. And the extrusion preventive ring 7 is manufactured harder than the seal ring 5 further softer than the valve surface 6. While in a valve closing condition that the valve surface 6 is adapted to the seal ring 5, the valve 9, forming a no-discharge part 8 by placing the valve surface 6 approaching or adapting it to the extrusion preventive ring 7, receives the seal ring 5, tending to extrude, to be stopped.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a lift valve that seals high-pressure fluid without leaking by bringing the valve surface of the valve body into contact with the seal ring of the valve seat. It belongs to the technical field and relates to technology that not only ensures high-pressure fluid flow but also improves its durability.

<Prior Art> Conventionally, as shown in FIG. 4, for example, an annular valve seat groove 44 is formed in a valve seat portion 43, a seal ring 45 is fitted into this valve seat groove 44, and a valve is inserted into this seal ring 45. body 42
A structure is known in which the valve is closed by bringing the valve surfaces 46 of the valve into contact with each other.

<Problems to be Solved by the Invention> The seal ring 45 is made of synthetic resin, rubber, or the like and is made of synthetic resin or rubber so as to be appropriately elastically deformed in order to come into close contact with the valve surface 46 and completely seal off the high-pressure fluid.

However, when used in a high-pressure fluid circuit of about 300 kg/cm2, for example, the seal ring 4S is pushed by the high-pressure fluid and the seal ring portion 45b on the downstream side of the flow path protrudes outside the valve seat groove 44. The contact pressure between the valve surface 46 and the valve surface 46 is not sufficiently increased, and high-pressure fluid leaks. For this reason, it is not possible to increase the pressure of the fluid circuit and downsize the fluid pressure device.

In addition, as the protruding portion 46b of the seal ring 45 gradually becomes larger during use, the seal ring 45 receives fluid pressure on its wide surface and is pushed out of the valve seat groove 44 when the valve is opened. It is easy for it to fall off and cause an accident when it cannot be closed.

Furthermore, the protruding portion 451 of the seal ring 45]
The corner 44a of the valve seat groove 44 and the valve surface 46 are quickly pinched, and the valve surface 46 comes into contact with the valve seat groove corner 44a, causing early damage. For this reason, the valve surface 46 receives the valve seat groove corner 44a1, and the contact surface pressure with the seal ring 45 decreases, causing fluid leakage, resulting in poor durability.

The present invention solves these problems and provides a strong seal even with high-pressure fluids, prevents the seal ring from falling off during use, and prevents damage to the seal ring and valve surface to ensure durability. The purpose is to enhance sexuality.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides an extrusion prevention ring 7 that prevents the seal ring 5 from being pushed out of the valve seat groove 4 by fluid pressure. The extrusion prevention ring 7 is made to be harder than the seal ring 5 and softer than the valve seat part 3 and the valve surface 6, and the valve surface 6 is made to be a seal. In the closed state where the valve is in contact with the ring 5, the valve surface 6 is close to or in contact with the extrusion prevention ring 7 to form a shutoff portion 8, and the seal ring 5 is about to be pushed out of the valve seat groove 4 by the fluid pressure. The seal ring 5 is received by the closing portion 8 to prevent the seal ring 5 from being pushed out of the valve seat groove 4.

<Example> Embodiments according to the present invention will be described below based on the drawings.

Figure 2 shows a lift valve according to the present invention as a safety valve for a hydraulic balanced overload safety device (hereinafter simply referred to as an overload safety valve).
FIG. 1 is an enlarged view of the main parts.

In FIG. 2, reference numeral 1 indicates a valve box, 2 indicates a valve body, 3 indicates a valve seat portion of the relief valve 9, 4 indicates a valve seat groove formed in an annular shape in the valve seat portion 3, and 5 indicates a valve seat groove formed in the valve seat groove 4. inset supported seal ring, 6
is the valve surface of the valve body 2, 9 is the relief valve, 10 is the relief valve cylinder, 11 is the relief valve return spring, 12 is the pressure oil inlet chamber, 13 is the outlet chamber, and 14 is the direction in which the valve body 2 is closed. 15 is a pump (not shown) that presses hydraulic oil into the hydraulic chamber 16 to operate, for example, a press machine. An inlet 17 is an auxiliary chamber of the valve body 2. 18 is a relief valve. This is a limit switch for stopping the drive motor (not shown) of the working machine in conjunction with the overload drive of No. 9.

First, the operation of the overload safety valve shown in FIG. 2 will be explained.

When the hydraulic pressure in the hydraulic chamber 16 becomes abnormally high and exceeds the set value, the hydraulic pressure in the inlet chamber 12 acts on the valve seat 3 of the relief valve 9 as shown by arrow A, increasing the set air pressure and the return spring 11. Push the relief valve 9 in the direction of arrow B. Then, the hydraulic oil flows into the auxiliary chamber 17 of the valve body 2, and the working surface 2a of the valve body 2
The valve body 2 is pushed back against the closing spring 14 to communicate the inlet chamber 12 and the outlet chamber 13, and the hydraulic oil is supplied to the inlet 15.
The oil is returned to the oil tank (not shown) through the inlet chamber 12, the valve body 2, the auxiliary chamber 17, and the outlet chamber 13, thereby safely protecting machines operated by pressure oil in the event of abnormally high pressure. It is composed.

Next, a lift valve according to the present invention applied to the above-mentioned overload safety valve will be explained. In Figures 1 and 2, reference numeral 7
is an extrusion prevention ring that is fitted and supported in the valve seat groove 4 in parallel with the seal ring 5 on the lower side of the oil path of the seal ring 5, and prevents the seal ring 5 from being pushed out of the valve seat groove 4 by hydraulic pressure. be.

This extrusion prevention ring 7 is manufactured to be harder than the seal ring 5 and softer than the valve seat portion 3 and the valve surface 6. For example, the seal ring 5 may be made of tetrafluoroethylene polymer (PTFE), nylon, Guiflon (trademark), etc. etc., and the extrusion prevention ring 7 is made of hard nylon, polyamide, etc. It is manufactured using resins mixed with fillers such as Delrin (trademark), Minlon (trademark), carbon glass, etc., or soft metals such as copper, zinc, and aluminum.

Further, in the closed state where the valve surface 6 is in contact with the seal ring 5, the valve surface 6 is close to or in contact with the extrusion prevention ring 7 to form a shutoff portion 8 as shown in FIG. Even if the seal ring 5 is pushed out of the valve seat groove 4 by arrow C, the seal ring 5 is stopped by the cutoff portion 8 to prevent it from being pushed out of the valve seat groove 4, and this cutoff portion 8 The seal ring 5 is pressed against the seal ring 5 to further enhance the sealing effect. The valve face 6 is made of a metal harder than the extrusion prevention ring 7 to prevent damage to the valve face 6 and leakage when the valve face 6 and the extrusion prevention ring come into contact.

FIG. 3 shows another embodiment of the lift valve according to the present invention, where 21 is a valve box, 22 is a valve body, 22a is a valve opening rod, 23 is a valve seat portion, 24 is a valve seat groove, 25 is a seal ring,
27 is an extrusion prevention ring, 32 is an inlet chamber, 33 is an outlet chamber, and 34 is a closing spring.

In FIG. 3, the seal ring 25 and the extrusion prevention ring 27 are arranged side by side in the valve seat groove 24 with the arrangement in FIG. It is arranged on the roadside and is configured to prevent the seal ring 25 from being pushed out of the valve seat groove 24 by hydraulic pressure.

<Effects of the Invention> The present invention is constructed and operates as described in section 2, and the valve surface of the valve body is located immediately after the point where the valve surface contacts the seal ring in the closed state, and is also close to or close to the extrusion prevention ring. The seal ring is brought into contact with the seal ring to form a shut-off portion, and the seal ring pressed by the fluid pressure is received by the shut-off portion to prevent it from protruding outside the valve seat groove, resulting in the following effects.

-7-B. As the seal ring is pressed against the shutoff part by fluid pressure, the surface pressure in contact with the valve surface there increases gradually, so the sealing effect increases and the high pressure fluid is strongly sealed.

This makes it possible to increase the pressure of the fluid circuit and downsize the fluid pressure device.

The opening and seal ring are received by the shut-off part and do not protrude outside the valve seat groove, so they will not be pushed out of the valve seat groove and fall off when the valve is opened, and sealing will not be possible during use. is lost.

C. The seal ring will not protrude outside the valve seat groove and be pinched between the corner of the valve seat groove and the valve surface, and the valve seat will not be damaged due to contact with the corner of the valve seat groove. As a result, the contact pressure between the seal ring and the valve surface can be maintained high for a long period of time, resulting in excellent durability.

[Brief explanation of drawings]

FIG. 2 is a cross-sectional view of the lift valve according to the present invention applied to an overload safety valve, FIG. 1 is an enlarged view of the main part thereof, and FIG. 3 is a cross-sectional view showing another embodiment of the lift valve according to the present invention. FIG. 4 is an enlarged sectional view of a part of the lift valve according to the prior art. 1... Valve box, 2... Valve body, 3... Valve seat, 4
...Valve seat groove, S...Seal ring, 6...
・Valve face, 7... Extrusion prevention ring, End... Closing part.

Claims (1)

[Claims] 1. The valve body 2 is provided in the valve box 1 so as to be movable towards and away from the valve seat portion 3, an annular valve seat groove 4 is formed in the valve seat portion 3, and a seal ring 5 is supported within the valve seat groove 4. , an extrusion prevention ring that prevents the seal ring 5 from being pushed out of the valve seat groove 4 by fluid pressure in a lift valve configured to close by bringing the valve face 6 of the valve body 2 into contact with the seal ring 5. 7 are juxtaposed on the downstream side of the flow path of the seal ring 5 and supported within the valve seat groove 4, and the extrusion prevention ring 7 is manufactured to be harder than the seal ring 5 and softer than the valve seat portion 3 and the valve surface 6. In the closed state where the valve surface 6 is in contact with the seal ring 5, the valve surface 6 is close to or in contact with the extrusion prevention ring 7 to form a shutoff portion 8, and is pushed out of the valve seat groove 4 by fluid pressure. The lift valve is characterized in that the seal ring 5 that is about to be removed is received by the closing portion 8 to prevent the seal ring 5 from being pushed out of the valve seat groove 4.