JPH10325472A - Seat ring for valve and valve using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the friction resistance to a valve element and the turning torque of the valve element for a long term by a simple seal structure and also obtain a favorable seal property, by forming a lubrication film excellent in a lubrication property on the contact surface of a rubber made seat ring main body with at least a valve element. SOLUTION: On the surface of a seat ring 4, a lubrication film is provided on the seal surface sealed by the contact with the valve element 2 and a valve element side surface. This lubrication film is bonded on the surface of the seat ring 4 by hardening and adhering, after mixing a main agent mixed a supper polymeric polyethylene powder with a graphite powder as a solid lubrication agent in an urethane resin with a hardening agent by the urethane resin at a prescribed rate and coating to a rubber made seat ring 4 main body. Thereby, as the seat ring 4 has the elasticity corresponding to an usual rubber and a little friction resistance to the valve element 2, and operation torque is not increased, even if a tightening allowance is enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat ring mounted on a valve seat for sealing by contacting a valve body rotating in a valve box, and a valve using the seat ring. The present invention relates to a device that can easily perform an opening / closing rotation operation of a valve body that rotates in the inside.

[0002]

2. Description of the Related Art Conventionally, as a seat ring used for a valve in which a valve element such as a ball valve rotates in a valve box, a single polytetrafluoroethylene resin (trade name: Teflon,
PTFE) or nitrile rubber is often used. Further, as disclosed in JP-A-63-140182, a ball valve in which a seat ring is formed from rubber obtained by mixing PTFE powder with heat-resistant rubber is also known. Further, as disclosed in Japanese Patent Application Laid-Open No. 7-55026, a seat ring made of a rubber elastic body and a seat ring made of PTFE resin are mounted in a valve box, and both seat rings seal with a ball valve body. Known ball valves are also known. Further, as shown in FIG. 8, there is also known a valve in which a PTFE seat ring is held by a seat member that slides in a valve box, and a disc spring is mounted on the back surface thereof.

[0003]

However, the former P
In a TFE seat ring, PTFE has a high expansion coefficient and is relatively hard, so that it expands at high temperatures. Therefore, there is a problem that the ball valve element 3 is restrained, and the rotational torque of the valve element increases, making opening and closing difficult. In addition, PTFE is inferior in creep resistance. For example, the seat ring expands in a state where the seat ring is in contact with the valve body, or the seat ring is compressed by the valve body due to fluid pressure when the valve is closed, and the PTFE flows on the outer peripheral surface of the valve body. However, there is a problem that creep occurs which causes plastic deformation in a state where the seat ring flows, and the fluid cannot be closed. That is, when the pressure is removed, a gap is formed between the ball valve body that is hermetically supported by the seat ring in the valve box and the ball valve body, and leaks from this gap. In order to eliminate this phenomenon, a complicated valve seal structure for providing elasticity to the back surface of the seat ring so as to elastically contact the valve element as in the rotary valve shown in FIG. 8 is further required.

In a rubber seat ring in which PTFE powder is mixed with heat-resistant rubber, PTFE powder is mixed in the process of forming the rubber sheet, and PTFE is mixed in the entire seat ring.
Since E is mixed, PTF per seat ring volume
It requires a large amount of E and is expensive. Further, since PTFE is dispersed throughout the rubber, the effect of reducing the coefficient of friction could not be greatly expected for a large amount of PTFE mixed. Further, in the case of a ball valve in which a rubber seat ring and a PTFE resin seat ring disclosed in JP-A-7-55026 are mounted in a valve box, a mounting groove or the like for mounting both seat rings in the valve box is provided. Processing and parts are required, and the number of parts of the seat ring increases, resulting in an expensive and complicated ball valve. Further, the rotary valve shown in FIG. 8 must have a structure in which the seat ring 9 slides in the valve box, and a seal packing 91, a disc spring 92, a seat member 93, a retaining ring 94 and the like for preventing back leakage. Is required, the number of parts is increased, and a complicated sealing mechanism is provided. SUMMARY OF THE INVENTION The present invention solves the above-described problems, and reduces the frictional resistance with the valve element over a long period of time with a simple sealing structure, thereby reducing the rotational torque of the valve element and obtaining a good sealing property. It is intended to provide a ring and a valve.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a seat ring for a valve which abuts on a valve body rotatably mounted in a valve box to seal between the valve body and the seat ring. A main body is provided, and at least a surface of the seat ring main body which is in contact with the valve body is coated with a resin solution in which a solid lubricant having excellent lubricity is mixed in a urethane resin and cured, and the surface of the rubber seat ring main body is cured. A seat ring for a valve, characterized in that a lubricating film is provided thereon. In the above, the solid lubricant is a valve seat ring comprising one or two of ultra-high molecular polyethylene, graphite, PTFE, and molybdenum disulfide. The thickness of the lubricating coating applied to the seat ring body is suitably about 2 to 20 μm. Further, the seat ring may have an annular lip projection formed at a portion where the seat ring comes into contact with a movable valve element in the valve box.

Further, a seat ring main body is provided with rubber, and at least a surface of the seat ring main body which is in contact with the valve body is coated with a resin solution in which a solid lubricant excellent in lubricity is mixed in a urethane resin and cured. A seat ring having a lubricating film formed on the surface of a rubber seat ring body is provided, the seat ring is mounted in a valve box, and a valve body rotatably mounted in the valve box is brought into contact with the valve body to form a gap. This is a valve characterized by sealing. In the above description, the valve may be a ball valve using a ball valve body having a spherical outer surface and a through-flow passage inside which communicates with the flow passage of the valve box. Further, the valve has a valve body sealing surface in which a rotary shaft of the valve body contacts the seat ring so that a sealing surface of the valve body is in close contact with the seat ring when the valve is closed, and the valve body is separated from the seat ring when the valve is opened. Eccentric rotary valve using a partially spherical valve element that rotates eccentrically from the center of curvature of the eccentric rotary valve.

[0008]

According to the present invention, a lubricating film having excellent lubricity is formed on at least the surface of the rubber seat ring body which is in contact with the valve body. Since the urethane resin containing the solid lubricant is hardened on the surface of the rubber seat ring main body, the lubricating coating adheres firmly and does not peel off. In addition, the urethane resin has similar mechanical properties to rubber, and the characteristics of the seat ring body itself are not impaired due to a thin film thickness formed by coating such as spraying. As a result, the excellent elasticity and creep resistance of the rubber itself are retained, and the seat ring body and the solid lubricant are firmly adhered to each other, so that they do not easily come off and the sliding friction resistance with the valve body is reduced. Stable lubrication performance can be obtained over a long period in a small amount. Therefore, the valve element can be easily rotated while holding the seat ring and the seal surface pressure, so that a valve can be easily operated for rotating the valve element. Further, the actuator for opening and closing can have a smaller capacity than before. In addition, since it only coats the seat ring body, the characteristics of the rubber seat ring body do not change, and it is possible to select the optimum rubber material according to the valve shape, performance, inflow fluid, working pressure, etc. The seal structure can be easily performed. In addition, since there is no need to use a conventional valve having a complicated seat mechanism or a seat ring in which rubber itself is made of a lubricating material, manufacturing costs are significantly reduced, and inexpensive and long-term operability is achieved. In addition, a valve having excellent sealing properties can be provided.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a ball valve showing one embodiment of the present invention, and FIG. 2 is a view showing a seat ring. In the figure, the valve box 1 has a valve chamber 6 and a valve chamber 6 inside.
The seat rings 4 and 4 and the ball valve body 2 are mounted in the valve chamber 6 and fixed by a retainer 8 screwed to the inlet / outlet flow path 7. The ball valve body 2 has a through hole 3 inside, and a valve stem 5 is connected to the upper part. By rotating the valve stem 5 from above, the ball valve body 2 rotates the inlet / outlet side flow path 7 in the valve box to the open or closed position, and the valve is opened and closed. Reference numeral 4 denotes a seat ring for sealing between the valve box 1 and the valve body 2, and FIG. The seat ring 4 is an annular body incorporated in a step portion on the valve chamber 6 side of the inlet / outlet flow path 7 of the valve box 1. In the present embodiment, the seat ring 4 is formed on the surface of the seat ring main body 4 entirely made of nitrile rubber. A lubricating film 43 is provided on the sealing surface and the valve body side surface that are in contact with and sealed.

The lubricating film 43 is obtained by preliminarily cleaning the preformed rubber seat ring main body 41 by degrease and cleaning with alcohol and drying at about 40 ° C. Next, a main agent obtained by mixing an ultra high molecular weight polyethylene powder and a graphite powder as a solid lubricant in a urethane resin, and a curing agent of the urethane resin are mixed at a ratio of about 2: 1 and sprayed or
The pretreated seat ring main body 41 is coated by brush coating or the like. This film thickness may be as thin as 20 microns or less, and sufficient performance is usually obtained at about 10 microns. Further, the main agent and the curing agent are diluted with a thinner to have an appropriate viscosity which facilitates coating. 80 ~ after coating
By heating at 90 ° C. for about 30 minutes, the urethane resin is securely cured and adhered to the rubber seat ring main body 41, and the lubricating coating 43 is firmly adhered to the surface of the seat ring 41. In addition, as the solid lubricant to be mixed into the urethane resin, PTFE or molybdenum disulfide may be used in addition to the above, and these may be appropriately mixed and used.

Although the shape of the seat ring main body 41 varies depending on the valve, as shown in FIG. 3, an annular lip 44 can be provided on the sealing side with the valve body 2 and on the mounting side with the valve box 1. In particular, by forming the lip 44 on the seal side with the valve body 2, the contact area in contact with the valve body 2 is reduced, the frictional resistance with the valve body 2 is further reduced, and the concentrated contact with the valve body 2 is increased. The sealing performance can be increased by the contact pressure.

FIG. 4 shows the structure of the seat ring 4 by the retainer 8.
The relationship between the interference of the seat ring that clamps the valve body 2 via the valve body and the operating torque of the valve stem 5 that rotates the ball valve body 2 is shown for each seat ring. The one using the seat ring 4 of the present invention has elasticity equivalent to ordinary rubber and low frictional resistance with the valve body 2, so that the operation is smaller than that of a conventional single PTFE or single rubber seat ring. The torque is small, and there is no increase in torque even if the seat ring tightening margin is increased. Therefore, the seat ring 4 of the present invention
Since the operating torque does not increase even if the tightening allowance is large, the seat ring can be tightened with a sufficient margin, so even if there is some error in the tightening allowance, it is possible to securely seal with a light operating torque. it can. This indicates that creep does not occur in the seat ring and the sealing performance is stabilized.

FIG. 5 shows the results of an open / close life test of a ball valve using the seat ring 4 of the present invention and a conventional single PTFE seat ring. Conventional PTFE sheet is about 5
Leakage occurred from the seat portion after every tenth opening and closing operation.
No abnormalities such as sheet leakage were observed up to 10,000 times. Further, in the product of the present invention, the increase in the operating torque did not change much even when the number of times of opening and closing increased, and the operating torque was about half that of the single PTFE seat ring. This means that the load on the motor of the actuator is small, and even a small capacity motor can be used.

FIGS. 6 and 7 show a valve according to another embodiment of the present invention. In this embodiment, the valve element 20 has a partially spherical sealing surface 22 at the peripheral edge of the valve plate 21 and an upper arm 23 and a lower arm 25 formed at the upper and lower portions of the back surface of the valve plate 21. The lower arm 25 is pivotally supported in the valve box 10 by the support pin 27 to rotate the valve body 20, and is brought into contact with the seat ring 30 provided in the one-side flow path 11 of the valve box 10. This is a valve that opens and closes the valve. As shown in FIG. 7, the center of rotation S of the valve body 20 is deviated from the center of curvature O of the valve body sealing surface 22 in the closed state by ΔY in a direction orthogonal to the flow axis X direction. Therefore, the valve body 20 contacts the seat ring 30 only when the valve body 20 is rotated near the fully closed position, and further rotates in the fully closed direction to increase the contact pressure with the seat ring 30 so that the valve can be completely closed. ing. Seat ring 30
Is fixed to an inner surface of the valve box by being held by an insert 12 screwed to an inner surface of the valve box flow path 11. This seat ring 30
In the same manner as in the previous embodiment, a lubricating film 33 is formed on the sealing surface of the rubber seat ring body in contact with the valve body sealing surface 22 and on the valve body 20 side.

In the case of such an eccentric rotary valve, the torque for rotating the valve body 20 is increased only when the valve is in contact with the seat ring 30 when the valve is opened but not in contact with the seat ring 30 when the valve is opened. is there. Conventionally, a single PTFE seat ring is often used as this seat ring, but if the contact pressure increases due to the rotational tightening of the valve body, the PTFE will creep and deform, causing problems with repeated opening and closing of the valve or long-term sealing performance. was there. For this reason, as in the rotary valve of FIG. 8, the seat ring has elasticity so that the seat ring escapes in the axial direction with respect to the pressure of the valve body, and a complicated seat such as inserting a spring such as a disc spring into the back surface of the seat ring. The structure had to be adopted. However, the seat ring 30 of the present embodiment
Since the frictional resistance with the valve body 20 is small and the creep characteristics of the rubber seat ring main body are good, there is no need to use a complicated structure as in the prior art, and it can be manufactured at low cost and can be used for a long time. And good sealing properties are maintained.

[0015]

As described above, according to the present invention, since the frictional resistance with the valve body is small, the opening and closing operability of the valve is excellent and the good sealing property is maintained over a long period of time, without increasing the number of parts. It is easy to manufacture and has excellent performance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a ball valve according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of the seat ring of FIG.

FIG. 3 is a sectional view showing a shape of a seat ring according to another embodiment.

FIG. 4 is a diagram showing a relationship between a seat ring interference and an opening / closing operation torque.

FIG. 5 is a diagram of a life test result showing a relationship between the number of opening / closing operations and an operation torque.

FIG. 6 is a view showing an eccentric rotary valve according to another embodiment of the present invention.

FIG. 7 is a view showing a valve body rotation center of the eccentric rotary valve of FIG. 6;

FIG. 8 is a cross-sectional view showing a conventional rotary valve sealing structure.

[Explanation of symbols]

 1, 10 Valve box 2, 20 Valve body 4, 30 Seat ring 5, 50 Valve stem 8, Retainer 12 Insert 41 Rubber seat ring main body 43 Lubricating coating 44 Lip projection

Claims (6)

[Claims] 1. A valve seat ring which abuts on a valve body rotatably mounted in a valve box to seal between the valve body and a valve body, wherein a seat ring main body is provided with rubber, and at least the seat ring main body is provided. A surface in contact with the valve body is coated with a resin solution obtained by mixing a solid lubricant having excellent lubricity in urethane resin and cured, and a lubricating film is provided on the surface of the rubber seat ring body. Valve seat ring. 2. The solid lubricant includes ultra-high molecular weight polyethylene, graphite, polytetrafluoroethylene (PT
2. The valve seat ring according to claim 1, wherein the valve ring comprises one or two of FE) and molybdenum disulfide. 3. The valve seat ring according to claim 1, wherein a thickness of the lubricating film coated on the seat ring body is about 2 to 20 μm. 4. A seat ring main body made of rubber is provided, and at least a surface of the seat ring main body that comes into contact with the valve body,
A resin solution in which a solid lubricant having excellent lubricity is mixed in urethane resin is coated and cured, and a seat ring having a lubricating film formed on the surface of the rubber seat ring body is provided.The seat ring is placed in a valve box. A valve using a seat ring, wherein the valve is mounted and abuts on a valve element rotatably mounted in a valve box to seal between the valve element. 5. The valve as set forth in claim 4, wherein the valve is a ball valve using a ball valve having a spherical outer surface and a through flow passage communicating with the flow passage of the valve box inside. Valve using a seat ring. 6. The valve according to claim 6, wherein, when the valve is closed, the sealing surface of the valve body is in close contact with the seat ring, and when the valve is open, the valve body is in contact with the seat ring such that the valve body is separated from the seat ring. The valve using a seat ring according to claim 4, wherein the valve is an eccentric rotary valve using a partially spherical valve element that rotates eccentrically from the center of curvature of the valve element sealing surface.