JPH072681U - Fluid pressure type pressure relief device for relief valve - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding a fluid pressure type pressure setting device for a relief valve, a friction pressure or a sliding resistance is remarkably reduced, and a fluid pressure type pressure setting device for a relief valve capable of preventing occurrence of sticking of a sealing member. The purpose is to provide. [Structure] A relief pressure setting cylinder 20 is provided on one side of the valve case 1, and a sealing member that seals between the cylinder case 21 of the cylinder 20 and the center desk 22 is provided on the center desk 22 at the inner peripheral portion. The bellows flam 23 is supported in a sealed manner and the outer peripheral portion is supported in a sealed manner by the cylinder case 21.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fluid pressure type pressure setting device for a relief valve.

[0002]

[Prior art]

 Generally, a relief valve is provided with a biasing means for biasing the valve element in a valve closing direction, and when the internal pressure of the hydraulic circuit exceeds a predetermined value, the hydraulic pressure resists this biasing means and opens the valve element. It is configured to be driven in the direction to allow a part or all of the pressure oil to escape to the return side and maintain the internal pressure of the hydraulic circuit at a set value.

As the urging means, for example, as disclosed in Japanese Patent Publication No. 54-23474, a cylinder such as an air cylinder, a spring, or a combination thereof may be considered. The cylinder used as the urging means of the relief valve, including the case where it is used together with the spring, is the cylinder case, the moving part inserted in the cylinder case so as to be displaceable in the axial direction, and the cylinder case and the motion. It has a sealing member that seals between it and the moving part, and a stem that is connected to the moving part and projects into the valve case.Piston is generally used as the moving part, and a moving member is used as the sealing member. O-rings and U-rings are used which are fitted in a peripheral groove formed in a portion, that is, the outer peripheral surface of the piston.

[0004]

[Problems to be solved by the device]

 However, the O-ring and U-ring are pressed against the inner peripheral surface of the cylinder case due to the pressure difference acting on both sides of the O-ring and U-ring, which causes large frictional resistance, resulting in large energy loss such as friction loss and hysteresis loss. If the inner peripheral surface and the surface of the peripheral groove of the piston are not finished with high accuracy, there are various problems such as leakage and occurrence of sticking of the O-ring and U-ring.

The present invention has been made in view of the above circumstances, and a frictional pressure or a sliding resistance is remarkably reduced, and a fluid pressure type pressure setting device for a relief valve capable of preventing sticking of a sealing member. It is intended to provide.

[0006]

[Means for Solving the Problems]

 The present invention is provided with a relief pressure setting cylinder on one side in the valve case, and this cylinder is used as a cylinder case, a moving part inserted in the cylinder case so as to be displaceable in the axial direction, and a cylinder case. The present invention is premised on a fluid pressure type pressure setting device for a relief valve having a sealing member for sealing between the moving part and a stem that is connected to the moving part and projects into the valve case. The following measures are taken to achieve this.

That is, it is characterized in that the sealing member is composed of a bellows having an inner peripheral portion sealedly supported by the moving portion and an outer peripheral portion sealingly supported by a cylinder case. In another relief valve fluid pressure type pressure setting device of the present invention, a ring made of a low sliding resistance member in which the sealing member is fitted and supported on the outer periphery of the moving part, instead of the bellows, is provided. And an elastic ring that urges in the radial direction.

[0008]

[Action]

 In the present invention using the bellows as a sealing member, the bellows has a portion between the inner peripheral portion and the outer peripheral portion that hangs down in a U-shape between the cylinder case and the moving portion, and the hanging portion of the bellows is the cylinder. It is located between the case and the moving part. It rolls, rolls and strokes during movement. Therefore, there is no friction with the inner peripheral surface of the cylinder case or the moving part, the friction loss is eliminated, and the hysteresis loss is significantly reduced.

Further, since the inner peripheral portion of the bellows is supported by the moving portion in a sealing manner and the outer peripheral portion is supported by the cylinder case in a sealing manner, the surface finishing accuracy of the inner peripheral surface of the cylinder case and the moving portion is improved. There is no risk of leakage regardless of In addition, since the bellows flam is in contact with the inner peripheral surface of the cylinder case and the moving part over a wide area, the contact pressure becomes low and it becomes difficult to stick.

As the low sliding resistance member used in the present invention using a ring made of a low sliding resistance member and an elastic ring as a sealing member, for example, a fluorine resin such as tetrafluoroethylene is used. By raising the ring made of this low sliding resistance member and slidingly contacting the inner surface of the cylinder case, the friction resistance against the movement of the moving part can be made smaller than the conventional rubber O-ring, and the friction loss can be reduced. Also, the hysteresis loss can be reduced, and the chemical characteristics of the low sliding resistance member are stable, so that the sealing member does not easily stick to the inner peripheral surface of the cylinder case.

In the present invention, the moving part of the relief pressure setting cylinder is not limited to a single moving part. For example, by forming the relief pressure setting cylinder by a tandem cylinder having a plurality of moving parts connected in a skewer shape, The power can be increased.

[0012]

【Example】

 Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a sectional view of a fluid pressure type pressure setting device for a relief valve according to an embodiment of the present invention, in which the left half shows a no-pressure state and the right half shows a main valve open state. There is. This relief valve is formed by arranging a primary chamber 2 communicating with an external pressure oil passage, a valve chamber 3 and a valve guide chamber 4 in this order in a coaxial center in the valve case 1, and the valve chamber 3 is the primary chamber. It is formed as a stepped different diameter chamber consisting of a small diameter chamber 5 on the 2 side and a large diameter chamber 6 on the valve guide chamber 4 side.

The main valve element 7 which is inserted into the valve chamber 3 so as to be able to move forward and backward in the axial direction thereof includes a small-diameter cylindrical portion 8 which is oil-tightly fitted in the small-diameter chamber 5 and a large-diameter chamber 6 in which The tapered cylindrical portion 9 and the large diameter cylindrical portion 10 which are successively connected are formed in a different diameter cylindrical shape, and the pilot valve seat 11 is formed on the inner peripheral surface of the connecting portion between the small diameter cylindrical portion 8 and the tapered cylindrical portion 9. It A pilot valve 12 is fitted in the large-diameter cylindrical portion 10 so as to be able to move forward and backward, and a tapered tapered valve surface 13 corresponding to the inner peripheral surface of the tapered cylindrical portion 9 is formed at the tip of the pilot valve 12. Is made.

An orifice 16 is formed in the taper cylinder portion 9 for communicating the hollow portion 14 of the main valve element 9 with a secondary chamber 15 defined in the valve chamber 3 by surrounding the main valve element 7. The large-diameter cylindrical portion 10 is closed by the pilot valve 12 when the distance between the pilot valve seat 11 and the pilot valve 12 is less than a certain value, and is opened when the distance is longer than that, and the hollow portion 14 and the hollow portion 14 of the main valve 7 are closed. A main valve hole 17 communicating with the next chamber 15 is formed.

In the valve guide chamber 4, a pilot valve guide piston 18 integrally assembled with the pilot valve 12 and a piston 18 slidably fitted on the piston 18 and slid in the valve guide chamber 4. A main valve guide cylinder 19 which is freely fitted therein is provided, and the main valve guide cylinder 19 is connected to the large diameter portion 10 of the main valve 7 in a stepped different diameter tubular shape. A relief pressure setting cylinder 20 is attached to the outside of the valve guide chamber 4 concentrically with the valve guide chamber 4. The cylinder 20 includes a cylinder case 21, a center desk 22 as a moving part that is inserted in the cylinder case 21 so as to be displaceable in the axial direction, and a sealing member that seals between the cylinder case 21 and the center desk 22. The stem 24 is connected to the bellows flam 23 and the center desk 22 and is inserted into the valve case 1 so as to be able to advance and retreat. The stem 24 receives the pilot child valve guide piston 18 at its tip.

A compressed air supply source 28 is connected via an air supply path 27 to a pressure receiving chamber 25 defined in the cylinder case 21 by the center desk 22 and the bellows flam 23 on the side opposite to the valve guide chamber 4. An air pressure supplied to the pressure receiving chamber 26 can be arbitrarily changed and set by a supply pressure adjusting device 29 provided in the air supply passage 27 (or the compressed air supply source 28).

Therefore, according to this fluid pressure type pressure setting device for the relief valve, the relief pressure of the relief valve can be controlled by changing the air pressure supplied to the pressure receiving chamber 26 by the supply pressure adjusting device 29. Since the setting can be changed by the control, it is possible to support flexible manufacturing which requires setting change of the relief pressure of the relief valve at an arbitrary place apart from the relief valve.

Further, by stopping the supply of compressed air to the pressure receiving chamber 26 and setting the internal pressure of the pressure receiving chamber 26 to 0, the pressure oil is automatically relieved from the primary chamber 2 side to the secondary chamber 15 side. Then, the kinetic energy inside the mechanical mechanism becomes zero, so-called zero mechanical state (Zero Mechanical State) can be set to improve the safety at rest and prevent the occurrence of product liability. it can.

Furthermore, since the bellows flam 23 is used as a sealing member that seals between the cylinder case 21 and the center desk 22, the bellows flank that hangs down in a U shape over the entire circumference between the cylinder case 21 and the center desk 22. Direct contact is prevented by 23, and therefore lubrication of the inner peripheral surface of the cylinder case 21 is not necessary, and there is no friction with the inner peripheral surface of the cylinder case 21 or the center desk 22, so there is no friction loss. And the hysteresis loss is significantly reduced.

In addition, the inner peripheral portion of the bellows flam 23 is supported by the center desk 22 in a sealing manner, and the outer peripheral portion is supported by the cylinder case 21 in a sealing manner. Irrespective of the surface finishing accuracy of the desk 22, there is no risk of leakage from the pressure receiving chamber 26 to the valve case 1 side, and accurate relief pressure control can be performed. In addition, since the bellows flam 23 is in contact with the inner peripheral surface of the cylinder case 21 and the center desk 22 over a wide area, the contact pressure is reduced, and the bellows flam 23 is in contact with the inner peripheral surface of the cylinder case 21 and the center desk 22. Almost no sticking to the outer peripheral surface.

FIG. 2 is a cross-sectional view of a fluid pressure type pressure setting device for a relief valve according to another embodiment of the present invention, in which the left half portion is a no-pressure state and the right half portion is a main valve opened state. Indicates. In this embodiment, the relief pressure setting cylinder 30 is composed of a tandem cylinder in which two center desks 33 are connected in a skewered shape. That is, in the cylinder case 31, there is provided a stepped, different-diameter cylindrical partition wall 40 that crosses the cross section of the cylinder case 31, and a center desk 32 and a bellows 33 are arranged on both sides of this partition wall 40, and are separated from the valve guide chamber 4. The stem 34a connected to one of the center desks 32 penetrates the partition wall 40 and is received by the stem 34b connected to the center desk 32 of the one closer to the valve guide chamber 4, and the stem 34a of the one closer to the valve guide chamber 4 is received. The stem 34b projects into the valve guide chamber 4 in the valve case 1, and the tip of the stem 34b receives the pilot valve 35.

In the cylinder case 31, the pressure receiving chamber 36 a, which is defined on the side opposite to the valve guide chamber 4 by the center desk 32 and the bellows 33 farther from the valve guide chamber 4, is compressed air via the air supply passage 37. The air pressure supplied to each pressure receiving chamber 26 can be arbitrarily changed and set by the supply pressure adjusting device 39 connected to the supply source 38 and provided in each branch air supply passage 37.

Further, in the cylinder case 31, the pressure receiving chamber 36 b defined between the center desk 32 and the bellows flank 33 closer to the valve guide chamber 4 and the partition wall 40 is a stem 34 a farther from the valve guide chamber 4. A pressure receiving chamber 36a located farther from the valve guide chamber 4 is communicated with an air passage 41 formed therein. In this embodiment, since the cylinder 30 is a tandem cylinder, the set pressure of the relief pressure can be made higher than that in the above-mentioned one embodiment. Further, the inner diameter of the cylinder case 31 required to obtain the same valve closing force can be made smaller than that of the single-acting cylinder, and the cylinder case 31 can be downsized.

Other configurations, operations and effects of this embodiment are the same as those of the above-mentioned one embodiment, and therefore their explanation is omitted to avoid duplication. FIG. 3 is a cross-sectional view of a fluid pressure type pressure setting device for a relief valve according to another embodiment of the present invention. In this embodiment, a moving portion of a relief pressure setting cylinder 50 is constituted by a piston 52 and is sealed. The member 53 is fitted in the groove 52a formed on the outer circumference of the piston 52 so as to be in sliding contact with the inner peripheral surface of the cylinder case 51.

The sealing member 53 is a ring 53a made of a low sliding resistance member such as tetrafluoroethylene, and an elastic ring arranged inside the ring 53a and urging the ring 53a in the radial direction. 53b and. When the portion of the sealing member 53 that slides in contact with the inner peripheral surface of the cylinder case 51 is formed by the ring 53a made of a low sliding resistance member, the friction resistance between the sealing member 53 and the cylinder case 51 is reduced. The pressure can be reduced, friction loss and hysteresis loss can be reduced, and the relief pressure can be set with high accuracy.

Further, since the ring 53a is chemically stable, sticking of the sealing member 53 to the inner peripheral surface of the cylinder case 51 is unlikely to occur. Incidentally, instead of being mounted on this piston, it can be mounted on the cylinder side, and a ring 53a made of a low sliding resistance member and an elastic ring 53b inside this ring 53a can be arranged on the sliding side. Illustration is omitted.

Other configurations, operations and effects of this embodiment are the same as those of each of the above-mentioned embodiments, and therefore description thereof will be omitted to avoid duplication.

[0028]

[Effect of device]

 As described above, in the present invention using the bellows as the sealing member, the bellows hanging between the cylinder case and the center desk prevent the cylinder case and the center desk from directly contacting each other. Since surface lubrication is not required and there is no friction with the inner peripheral surface of the cylinder case or the center desk, friction loss is eliminated and hysteresis loss is significantly reduced.

In addition, since the inner peripheral portion of the bellows is sealedly supported by the center desk and the outer peripheral portion is sealingly supported by the cylinder case, the inner peripheral surface of the cylinder case and the surface finish of the center desk are finished. Leakage from the pressure receiving chamber to the valve case side is eliminated regardless of accuracy, and accurate relief pressure control is possible. Moreover, since the bellows is in contact with the inner peripheral surface of the cylinder case and the center desk over a wide area, the contact pressure is reduced, and the bellows is stuck to the inner peripheral surface of the cylinder case and the outer peripheral surface of the center desk. Is almost gone.

In the present invention, the sealing member is composed of a ring made of a low sliding resistance member fitted and supported on the outer periphery of the moving part, and an elastic ring for urging the ring in the radial direction. In this case, the frictional resistance between the sealing member and the cylinder case can be reduced, the friction loss and the hysteresis loss can be reduced, and the relief pressure can be set with high accuracy.

Further, since the chemical characteristics of the low sliding resistance member are stable, the sealing member does not easily stick to the inner peripheral surface of the cylinder case.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of another embodiment of the present invention.

FIG. 3 is a cross-sectional view of another embodiment of the present invention.

[Explanation of symbols]

 1 Valve case 20, 30, 50 Cylinder 21, 31, 51 Cylinder case 22, 32 Center desk 23, 33 Bellow flam 24, 34a, 34b Stem 52 Piston 53 Sealing member 53a Ring 53b Elastic ring

Claims (3)

[Scope of utility model registration request] 1. A relief pressure setting cylinder is provided on one side of a valve case, the cylinder case, a moving part inserted in the cylinder case so as to be displaceable in the axial direction thereof, the cylinder case and the moving part. In a fluid pressure type pressure setting device for a relief valve having a sealing member that seals between the moving member and a stem that projects into the valve case, the sealing member seals the inner peripheral portion to the moving member. A fluid pressure type pressure setting device for a relief valve, which is constituted by a bellows which is supported in a stationary manner and whose outer peripheral portion is supported in a sealed manner by a cylinder case. 2. A ring made of a low sliding resistance member, in which the sealing member is fitted and supported on the outer periphery of the moving portion of the piston or the inner periphery of the cylinder, instead of the bellows flank, and the ring is attached in the radial direction. The fluid pressure type pressure setting device for the relief valve according to claim 1, wherein the fluid pressure type pressure setting device is constituted by an elastic ring for urging. 3. An air pressure type pressure setting device for a relief valve according to claim 1, wherein the relief pressure setting cylinder comprises a tandem cylinder having a plurality of moving parts connected in a skewer shape.