JP2019049333A - Ball valve - Google Patents

Abstract

To provide a ball valve that can stabilize operation torque of a valve element at desired torque, and can reliably prevent inner fluid from leaking.SOLUTION: A ball valve 1 comprises: a valve element 2 of which an outer surface is a spherical surface, and comprising a through hole; a thermoplastic resin-made valve casing 3 comprising a drum part 31 comprising a valve element housing part in which the valve element is housed, and a side part 32 integrated with the drum part 31; and a seat ring 4 fitted between the outer surface of the valve element 2 and an inner surface of the valve casing 3. The drum part 31 comprises an outer cylinder part 312. The side part 32 comprises an inner cylinder part 321 inserted into the outer cylinder part 312. In the drum part and the side part, an inner surface of the outer cylinder part 312 and an outer surface of the inner cylinder part 321 are melted and integrated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ball valve, and more particularly to a ball valve made of thermoplastic resin such as polyethylene.

  BACKGROUND ART Conventionally, a pipe made of a thermoplastic resin such as polyethylene, which is excellent in earthquake resistance, is widely used for piping such as city gas and drinking water. In such piping, when work such as road construction, use is made of a ball valve having a valve body that can temporarily shut off the flow of fluid in the pipe and release the shutoff after the work is completed. It is done.

  The ball valve includes a spherical valve body, a valve case housed in a thermoplastic resin valve box as well as a tube, and a seat ring sealing between the valve body and the valve box. The valve box is constituted by a body portion in which a space for accommodating the valve body is formed, and a side portion provided at both ends of the body portion and having a connection portion connectable with the pipe. According to this type of ball valve, the flow path is opened and closed by rotating the valve body inside the valve box. This type of ball valve is manufactured, for example, as follows. First, the valve body is set inside the body, and then the side where the seat ring is mounted at the end is integrated with the body at a position where the seat ring is sealed with the valve body .

  Conventionally, in the method of integrating the body and the side, a butt is performed by bringing the ends of both members into contact with the heating plate, heating and melting, and then bringing the ends into close contact and pressurizing the members. Fusing is known and is in practical use. According to this method, the integration can be relatively easy because the integration can be achieved simply by bringing the ends of the heat-melted members into close contact and pressing. On the other hand, it is difficult to integrate the members with high positional accuracy due to variations in melting conditions and pressure conditions.

  By the way, from the viewpoint of workability of the opening and closing operation of the valve body, it is desired that the operation torque of the ball valve is stable in a size (for example, 50 Nm or less) which can easily open and close the valve body. In order to realize that, in order to stabilize the compression state of the seat ring in the valve box, the body portion and the connection portion must be integrated with high positional accuracy.

  Therefore, as shown in FIG. 5 in Patent Document 1, in the ball valve in which the body 310 and the side portion 320 are integrated by butt fusion to form the valve box 30, the body portion 310 and the side portion are formed. Fitting portions 310a and 320a to be fitted with 320 are formed, and the tip end portion 320b of the side fitting portion 320a and the contact surface 310b of the body side fitting portion 310a abut each other during butt fusion. The ball valve 10 is described in which the body portion and the connection portion are positioned in the direction of the arrow X (hereinafter referred to as the X direction) in the figure. According to this ball valve 10, since it is positioned in the X direction by the contact between the contact surface 310b which does not melt at the time of butt fusion in the fitting portions 310a and 320a and the tip portion 320b, the body 310 and the side portion 320 Can be integrated with high positional accuracy in this direction. Thereby, the contact between the valve body 20 and the valve box 30 and the seat ring 40 is stabilized, and the operating torque of the valve body is stabilized.

Japanese Patent Application Laid-Open No. 10-205637

  The ball valve described in Patent Document 1 has a structure in which the body portion 310 and the side portion 320 are integrated by butt fusion, so that it is always desired on the surface to be fused at the time of fusion in order to firmly integrate. Pressure needs to be applied. However, since the ball valve described in Patent Document 1 has a structure in which the contact surface 310b of the fitting portions 310a and 320a and the tip end 320b contact at the time of fusion, the force applied along the X direction at the time of fusion Many of them may be received by the contact surface 310b and the tip 320b and may not be transmitted sufficiently to the surface to be fused. As a result, the strength of the joint between the body 310 and the side part 320 is insufficient, and there is a concern that the internal fluid may leak due to the breakage of the joint.

  The present invention has been made in view of the above-mentioned problems in the prior art, and can stabilize the operating torque of the valve body at a desired torque and reliably prevent the internal fluid from leaking out. It aims to provide a ball valve that can be

  In order to achieve the above object, a ball valve according to the present invention has a valve body having a through hole and a spherical outer surface, and a valve body accommodating portion for accommodating the valve body. A ball valve comprising a thermoplastic resin valve box having a body and a side portion integrated with the body, and a seat ring mounted between an outer surface of the valve body and an inner surface of the valve box. The body has an outer cylinder portion on at least one side of the valve body accommodation portion, the side portion has an inner cylinder portion inserted into the outer cylinder portion, and the body portion and the side portion The inner cylinder part is inserted in the outer cylinder part, and the inner surface of the outer cylinder part and the outer surface of the inner cylinder part are melted and integrated.

  Further, in the ball valve according to the present invention, positioning means for positioning the inner cylindrical portion in the axial direction in the outer cylindrical portion when the inner cylindrical portion is inserted into the outer cylindrical portion in at least one of the trunk portion and the side portion. It is preferable to have In the present specification, the axial direction means the direction along the axis of the outer cylinder.

  Further, in the ball valve according to the present invention, the positioning means can include a hooking portion provided on at least a part of the outer cylinder and the inner cylinder and the outer cylinder and the inner cylinder being hooked. .

  In the ball valve according to the present invention, the means for melting the inner surface of the outer cylinder portion and the outer surface of the inner cylinder portion is provided on the inner surface of the outer cylinder portion or the outer surface of the inner cylinder portion. Heating wire can be included.

  In the ball valve according to the present invention, preferably, the seat ring has a solid lubricant at least on the surface in contact with the outer surface of the valve body. In the ball valve according to the present invention, the solid lubricant may contain fluorine.

  As described above, according to the ball valve of the present invention, it is possible to stabilize the operating torque of the valve at a desired torque, and it is possible to reliably prevent the internal fluid from leaking out.

It is a perspective view of a ball valve concerning the present invention. It is a longitudinal section of a ball valve concerning the present invention. It is a disassembled sectional view of a ball valve concerning the present invention. It is a half cut sectional view of a seat ring. It is sectional drawing which shows the ball valve of a prior art.

  DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described here is merely an example of the embodiment of the present invention, and the present invention is not limited thereto.

First Embodiment
1, 2 and 3 show an example of a ball valve according to the present invention. 1 is a perspective view (showing a partial cross section) showing the appearance of the ball valve, FIG. 2 is a cross sectional view of the ball valve, FIG. 3 is a cross sectional view showing the parts of the ball valve disassembled, and FIG. It is a half cutting sectional view of a ring. The ball valve of the present embodiment is symmetrical in the X direction about the rotation axis of the valve body. Therefore, in FIG. 3, the side part 32 which is the same shape shows only the right side, and illustration of the left side is abbreviate | omitted.

  As shown in FIGS. 1 and 2, the ball valve 1 has a valve body 2, a valve box 3 and a seat ring 4. In the ball valve 1, the valve body 2 supported by the valve rod 5 and the pin 6 inside the valve case 3 is operated to shut off and open the flow path in the ball valve. The flow of fluid from the side to the downstream can be shut off and released. The detail of each part which comprises the ball valve 1 is demonstrated in order.

  As shown in FIG. 3, the valve body 2 is formed such that at least the outer surface 21 of the outer surface in contact with the seat ring 4 is a spherical surface, and has a hole 22 penetrating therethrough. At the top of the valve body 2 is formed a valve rod mounting recess 23 into which the end of the valve rod 5 is inserted. In the present specification, the upper portion refers to the upper side in the direction along the arrow Y in the figure, and the lower portion refers to the lower side in the direction along the arrow Y. The valve rod mounting recess 23 is formed to have the same cross-sectional shape (for example, a square cross section, a hexagonal cross section, etc.) as the end of the valve rod 5, and the inserted valve rod 5 and the valve body 2 are valve rods. It does not rotate relatively around the central axis of 5. Therefore, the valve body 2 can be operated by rotating the valve rod 5 from the outside of the valve box 3. In the lower part of the valve body 2, a pin mounting hole 24 is formed along the rotation axis of the valve body 2 so as to penetrate from the hole 22 to the outside of the valve body 2. A pin 6 serving as a rotational shaft of the valve body 2 is inserted into the pin mounting hole 24 so as to straddle the valve case 3. The valve body 2 can select and use metal materials, such as iron, and resin materials, such as polyacetal, according to the required specification (for example, cost and mass). The ball valve of this embodiment is a ball valve of a so-called trunnion structure in which the valve body 2 is supported on the valve box 3 by the valve rod 5 and the pin 6, but in the present invention, the pin 6 is omitted and only the valve rod is used. The present invention can also be applied to a ball valve of so-called floating structure that is supported.

  The valve box 3 is composed of a body 31 and a side portion 32. The body portion 31 has a valve body accommodating portion 311 in which the valve body 2 is accommodated on the inner diameter side, and outer cylinder portions 312 on both sides of the valve body accommodating portion 311. In the upper part of the valve body accommodation portion 311, a valve rod mounting hole 313 is formed in which the inner surface and the outer surface penetrate and the valve rod 5 of the valve gymnastics function is inserted. A pin groove 314 into which the pin 6 is fitted is formed in the lower portion of the valve body accommodation portion 311.

  The side portion 32 has an inner cylindrical portion 321 inserted on the inner diameter side of the outer cylindrical portion 312 and a connection portion 322 connected to a pipe not shown. A heating wire 323, which generates heat when energized, is wound around the outer periphery of the inner cylindrical portion 321. Further, at the rear end of the inner cylindrical portion 321, a hooking portion 324 having a diameter larger than that of the inner cylindrical portion 321 is formed. The hooking portion 324 positions the inner cylindrical portion 321 in the axial direction in the outer cylindrical portion 312 by coming into contact with the end of the body portion 31 when the inner cylindrical portion 321 is inserted into the outer cylindrical portion 312. It is a positioning means. A step 325 to which the seat ring 4 is attached is formed on the inner diameter side of the inner cylindrical portion 321.

  As shown in FIG. 2, in the body portion 31, the valve body 2 is mounted inside, and the side portions 32, 32 are joined so as to sandwich the valve body 2 from both sides in the X direction. The inner cylinder portion 321 is inserted into the outer cylinder portion 312 until the hooking portion 324 abuts on the end surface of the body portion 31 and the side portion 32, and the electric heating wire 323 is energized at that position. The outer surface of the cylindrical portion 321 and the inner surface of the outer cylindrical portion 312 are melted and integrated. The hooking portion 324 is formed at the rear end of the inner cylindrical portion 321 which is not affected by the deformation due to the energization of the heating wire 323, so the axial direction of the body 31 and the side portion 32 before and after integration. The relative position does not change. Furthermore, the axial position of the seat ring 4 mounted at the end of the side portion 32 after integration is stabilized. Thus, the outer cylinder part 312 and the inner cylinder part 321 are fused in the outer surface and the inner surface and integrated in the radial direction (Y direction in the figure). According to this joining method, the face to be fused faces in the axial direction (X direction in the figure), and the target is moved in the axial direction at the time of fusing more easily and accurately than the joining method such as butt fusion. , And axial positioning of the members can be performed. In addition, since the seat ring 4 can be easily installed at an axial position in the body portion 31 which is designed in advance so that the operation torque of the valve body 2 becomes an appropriate magnitude, The operating torque can be easily stabilized.

  The material of the body 31 and the side 32 is selected according to the material of the pipe to be connected, for example, in the case of a ball valve connected to a polyethylene pipe widely used for buried piping of city gas, etc. Polyethylene is used for the material of 31 and the side 32.

  As shown in FIG. 4, the seat ring 4 is an annular member having elasticity with a substantially rectangular longitudinal cross section along the X direction. The seat ring 4 has an elastic portion 41 made of an elastic material in close contact with the valve body 2 and the step portion 325, and a core portion 42 made of metal. In the elastic portion 41, a coating of a solid lubricant is applied to at least a sheet surface 43 in contact with the valve body 2 on the surface. As described above, since the friction between the valve body 2 and the elastic portion 41 is reduced by having the coating of the solid lubricant on the surface of the elastic portion 41, the valve does not require application of a wet lubricant such as grease. The operating torque of the body 2 can be reduced. Further, since foreign substances are less likely to adhere than when a wet type lubricant such as grease is applied, it is possible to suppress biting of foreign substances such as sand or dust between the valve body 2 and the seat ring 4. Furthermore, the leakage of the fluid accompanying the sealing fall resulting from this is suppressed. For example, rubber such as nitrile butadiene rubber (NBR) or ethylene propylene diene rubber (EPDM) can be used for the elastic portion 41. The material of core part 42 can use metal materials, such as iron, for example. For the solid lubricant, for example, a fluorine-based solid lubricant such as polytetrafluoroethylene can be used.

  In addition to coating a solid lubricant on the surface, the reduction of friction of the seat ring 4 is also realized by forming an elastic portion 41 by an elastic material into which a solid lubricant such as fluorine, carbon and molybdenum disulfide is kneaded. be able to. For example, when used in a particularly low temperature range such as -30.degree. C., it is preferable to use, for the elastic portion 41, a material excellent in cold resistance performance such as silicone rubber.

Second Embodiment
In the ball valve 1 according to the first embodiment, the side portion 32 provided as a separate component on both sides (right and left sides in FIGS. 1 to 3) of the body portion 31 is fused to constitute the valve box 3 However, one side (for example, the left side in the figure) and the body may be pre-formed integrally by, for example, injection molding. The ball valve of the second embodiment is easy to manufacture because the number of portions to be melted and integrated is small.

Third Embodiment
In the ball valve 1 of the first and second embodiments, the body portion 31 and the side portion 32 are melted and integrated by the heating wire 323 wound around the inner cylindrical portion 321 formed on the side portion 32. However, the heating wire may be provided on the inner surface of the outer cylinder of the body.

  Alternatively, a sheet-like heating element may be separately provided between the inner surface of the outer cylinder and the outer surface of the inner cylinder, and the inner surface of the outer cylinder and the outer surface of the inner cylinder may be melted and integrated by heating the heating element. .

  Needless to say, various modifications can be made without departing from the spirit of the present invention.

1: Ball valve 2: Valve body 21: Outer surface 22: Hole portion 23: Valve rod mounting recess 24: Pin mounting hole 3: Valve box 31: Body portion 311: Valve body accommodating portion 312: Outer cylinder portion 313: Valve rod mounting Hole 314: Pin groove 32: Side portion 321: Inner tube portion 322: Connection portion 323: Heating wire 324: Retaining portion 325: Step portion 4: Seat ring 41: Elastic portion 42: Core portion 43: Seat surface 5: Valve Rod 6: Pin

Claims (6)

A valve body having a hole passing therethrough and having an outer surface formed on a spherical surface;
A thermoplastic resin valve box having a body portion having a valve body accommodating portion in which the valve body is accommodated, and a side portion integrated with the body portion;
A seat ring mounted between the outer surface of the valve body and the inner surface of the valve box;
A ball valve comprising
The body portion has an outer cylinder portion on at least one side of the valve body accommodation portion,
The side portion has an inner cylindrical portion inserted into the outer cylindrical portion,
The inner cylinder portion is inserted into the outer cylinder portion, and the inner surface of the outer cylinder portion and the outer surface of the inner cylinder portion are melted and integrated. Ball valve. At least one of the body portion and the side portion has positioning means for positioning the inner cylindrical portion in the axial direction in the outer cylindrical portion when the inner cylindrical portion is inserted into the outer cylindrical portion. ing,
The ball valve according to claim 1. The positioning means is provided on at least a part of the outer cylindrical portion and the inner cylindrical portion, and includes a hooking portion on which the outer cylindrical portion and the inner cylindrical portion are hooked.
The ball valve according to claim 2. The means for melting the inner surface of the outer cylinder portion and the outer surface of the inner cylinder portion is provided on the inner surface of the outer cylinder portion or the outer surface of the inner cylinder portion, and includes a heating wire which generates heat by energization.
The ball valve according to any one of claims 1 to 3. The seat ring has a solid lubricant at least on the surface in contact with the outer surface of the valve body.
The ball valve according to any one of claims 1 to 4. The solid lubricant contains fluorine,
The ball valve according to claim 5.

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