Plug valve with elastic automatic compensating seal

Abstract

The present invention relates to a plug valve with elastic automatic compensation seal, including a valve body, a valve cover, a plug body, a valve stem, and a transmission mechanism. The bushing between the valve body and the plug body is composed of a left half bushing and a right half bushing. The left half bushing and the right half bushing have an axial gap in the center line direction of the valve body channel, and a floating seal pair is formed between the bushing and the plug body to automatically compensate for the wear of the seal pair. The conical cylindrical cavity of the valve body can be finely processed to obtain a high-precision inner cavity wall, which solves the problem that the prior art needs to set anti-rotation ribs in the inner cavity but cannot be finely processed, and reduces the precision requirements for the valve body casting. It has the advantages of small opening and closing torque, low requirements for valve body casting precision, convenient processing, and high use pressure.

Description

Technical Field

[0001] The invention belongs to the field of valves, in particular to a soft-sealed plug valve. Background Art

[0002] The structure of a soft-sealed plug valve generally consists of a valve body, a valve cover, a valve stem, and a plug body. A plastic sealing ring is embedded in the inlet and outlet of the valve body, or a fluoroplastic is lined in the valve cavity to cooperate with the conical cylindrical surface of the plug body to form a soft sealing pair. For example, the soft-sealed plug valve with application number CN201610967458.3 includes a valve body, a plug and a bushing. The bushing is fixed to the hole wall of the flow channel hole.

[0003] The plug is pressed into the bushing hole and cooperates with the bushing to form a sealing pair. Its main disadvantages are: during the opening and closing process, the outer cylindrical surface of the plug is in sealing contact with the bushing, and when the plug rotates, it generates a large friction with the bushing, resulting in a large opening and closing torque, which makes the existing plug valve only suitable for low-pressure working conditions; the valve body is generally cast, and the bushing is pressed into the flow channel hole of the valve body. Generally, anti-rotation ribs need to be set in the inner cavity of the valve body, which has high requirements on the quality of the valve body casting and is difficult to process. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a plug valve with elastic automatic compensation seal, which has small opening and closing torque, low requirements on valve body casting quality, convenient processing and high use pressure.

[0005] The technical solution of the present invention includes a valve body, a valve cover, a plug body, a valve stem, and a transmission mechanism. The valve body has a tapered cylindrical cavity and an inlet and outlet passage connected to the tapered cylindrical cavity. The plug body is a tapered cylinder that cooperates with the tapered cylindrical cavity. The plug body is provided with a flow channel hole that cooperates with the inlet and outlet passages of the valve body. A bushing is provided between the plug body and the tapered cylindrical cavity of the valve body. The bushing is characterized in that: the bushing is composed of a left half bushing and a right half bushing located on the left and right sides of the center line of the valve stem. The left half bushing and the right half bushing are respectively provided with flow channel holes of the same shape and size as the flow channel holes of the plug body. The left half bushing and the right half bushing are respectively provided with flow channel holes of the same shape and size as the flow channel holes of the plug body. The valve cover through the upper end face is pressed into the conical cylindrical cavity of the valve body, and there is a gap between the facing end faces of the left half bushing and the right half bushing; the outer cylindrical surfaces of the left half bushing and the right half bushing are provided with rubber sealing rings concentric with the flow channel hole, and the inner cylindrical surfaces of the left half bushing and the right half bushing are embedded with flexible non-metallic sealing rings concentric with the flow channel hole, and the sealing surfaces of the flexible non-metallic sealing ring and the plug body protrude from the inner cylindrical surfaces of the left half bushing and the right half bushing; anti-rotation grooves are respectively provided in the middle positions of the upper end faces of the left half bushing and the right half bushing, and anti-rotation blocks are provided on the valve covers directly above the anti-rotation grooves, and the anti-rotation blocks are embedded in the anti-rotation grooves.

[0006] In the above technical scheme, spring grooves are respectively formed on the outer circumference of the flow hole of the outer cylindrical surface of the left half bushing and the right half bushing, and disc springs are respectively installed between the spring grooves and the inner wall of the tapered cylindrical cavity of the valve body; left convex rings and right convex rings are respectively provided on the outer cylindrical surfaces of the left half bushing and the right half bushing surrounding the flow hole, and grooves that dynamically seal with the left convex ring and the right convex ring are respectively formed on the inner wall of the tapered cylindrical cavity of the flow hole of the inlet and outlet channels of the valve body, and rubber sealing rings are arranged between the outer ring surfaces of the left convex ring and the right convex ring and the outer groove walls of the grooves that cooperate with each other.

[0007] In the above technical solution, the lower end face of the valve cover is provided with an annular sealing groove which is concentric with the valve stem mounting hole, and an annular sealing gasket is embedded in the annular sealing groove, and the annular sealing gasket is in sealing contact with the upper end face of the plug body; a sealing gasket is installed between the valve stem and the upper end face of the valve cover, and the sealing gasket and the annular sealing gasket form a double sealing structure of the middle cavity.

[0008] In the above technical solution, a positioning shaft which is concentric with the valve stem is provided on the lower end surface of the plug body, and the positioning shaft is inserted into the positioning hole on the upper end surface of the lower cover.

[0009] Compared with the prior art, the present invention has the following beneficial effects: the sleeve between the valve body and the plug body is composed of a left half sleeve and a right half sleeve, and the left half sleeve and the right half sleeve have an axial gap in the center line direction of the valve body channel, forming a floating seal pair between the sleeve and the plug body, automatically compensating for the wear of the seal pair; the conical cylindrical cavity of the valve body can be finely machined to obtain a high-precision inner cavity wall, solving the problem that the prior art needs to set anti-rotation ribs in the inner cavity and cannot be finely machined, and reducing the precision requirements for the valve body casting. It has the advantages of small opening and closing torque, low requirements for valve body casting precision, convenient processing, and high use pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the present invention.

[0011] Figure 2 The present invention Figure 1 Schematic diagram of the structure of the inner circular surface of the left half bushing and the right half bushing.

[0012] In the figure: 1 valve body, 2 left half bushing, 3 plug body, 4 left convex ring, 5 right half bushing, 6 anti-rotation block, 7 valve cover, 8 annular sealing gasket, 9 sealing gasket, 10 valve stem, 11 transmission mechanism, 12 disc spring, 13 flexible non-metallic sealing ring, 14 right convex ring, 15 positioning shaft, 16 lower cover, 17 rubber sealing ring, 18 anti-rotation groove. DETAILED DESCRIPTION

[0013] like Figure 1The plug valve with elastic automatic compensation seal shown in the figure comprises a valve body 1, a valve cover 7, a plug body 3, a valve stem 10, and a transmission mechanism 11. The valve body 1 has a tapered cylindrical cavity and an inlet and outlet channel connected to the tapered cylindrical cavity. The tapered cylindrical cavity refers to the inner cavity of the valve body 1 having a tapered inner cavity wall, forming a tapered cylindrical cavity with an upper port diameter greater than a lower port diameter. The plug body 3 is a tapered cylinder that cooperates with the tapered cylindrical cavity. The plug body 3 is provided with a flow channel hole that cooperates with the inlet and outlet channels of the valve body 1. The flow channel hole is a square hole composed of upper and lower arc surfaces and two sides of the plug body 3 with the same taper plane. A bushing is arranged between the conical cylindrical cavity of the valve body 1 and the left half bushing 2 and the right half bushing 5, which are located on the left and right sides of the center line of the valve stem 10. The left half bushing 2 and the right half bushing 5 are respectively provided with flow holes of the same size and shape as the flow holes of the plug body 3. The left half bushing 2 and the right half bushing 5 are press-fitted into the conical cylindrical cavity of the valve body 1 through the valve cover 7 on the upper end face. The flow holes of the two are aligned with the flow holes of the inlet and outlet channels of the valve body 1. There is a gap between the facing end faces of the left half bushing 2 and the right half bushing 5, which provides a left-right movement space for the left half bushing 2 and the right half bushing 5. The outer cylindrical surfaces of the sleeve 2 and the right half bushing 5 are provided with a rubber sealing ring concentric with the flow channel hole to achieve sealing with the inner wall of the tapered cylindrical cavity of the valve body 1. The inner cylindrical surfaces of the left half bushing 2 and the right half bushing 5 are embedded with a flexible non-metallic sealing ring 13 concentric with the flow channel hole to achieve sealing with the plug body 3. The sealing surface of the flexible non-metallic sealing ring 13 cooperating with the plug body 3 protrudes from the inner cylindrical surfaces of the left half bushing 2 and the right half bushing 5, so that the plug body 3 and the flexible non-metallic sealing ring 13 cooperate with each other to form an elastic automatic compensation sealing pair, which reduces the contact area between the plug body 3 and the bushing, reduces the opening and closing torque, and after the sealing surface is worn The medium pressure pushes the left half-bushing 2 located on the inlet side to press the plug body 3 to seal, automatically compensate for the wear of the sealing surface, and has good sealing performance; the flexible non-metallic sealing ring 13 adopts a wear-resistant rubber sealing ring, which is embedded in the dovetail grooves of the left half-bushing 2 and the right half-bushing 5 to prevent the flexible non-metallic sealing ring 13 from falling off when the plug body 3 rotates; anti-rotation grooves 18 are respectively provided in the middle position of the upper end surfaces of the left half-bushing 2 and the right half-bushing 5, and an anti-rotation block 6 is provided on the valve cover 7 directly above the anti-rotation groove 18, and the anti-rotation block 6 is embedded in the anti-rotation groove 18 to prevent the left half-bushing 2 and the right half-bushing 5 from rotating when the plug body 3 rotates.

[0014] Spring grooves are respectively formed on the periphery of the flow hole on the outer cylindrical surface of the left half bushing 2 and the right half bushing 5, and disc springs 12 are respectively installed between the spring grooves and the inner wall of the tapered cylindrical cavity of the valve body 1, so that the left half bushing 2 and the right half bushing 5 are pressed and sealed against the plug body 3 to increase the sealing pressure ratio and improve the sealing performance; left convex rings 4 and right convex rings 14 are respectively provided on the outer cylindrical surfaces of the left half bushing 2 and the right half bushing 5 around the flow hole, and grooves for dynamic sealing with the left convex ring 4 and the right convex ring 14 are respectively formed on the inner wall of the tapered cylindrical cavity on the periphery of the flow hole of the inlet and outlet channels of the valve body 1, and rubber sealing rings 17 are arranged between the outer ring surfaces of the left convex ring 4 and the right convex ring 14 and the outer groove walls of the grooves that cooperate with each other, so as to realize the sealing between the left half bushing 2 and the right half bushing 5 and the valve body 1 and further improve the sealing performance. The left convex ring 4 can be integrally formed with the left half bushing 2, or can be connected by welding; similarly, the right convex ring 14 can be integrally formed with the right half bushing 5, or can be connected by welding.

[0015] The lower end surface of the valve cover 7 is provided with an annular sealing groove concentric with the valve stem mounting hole, and an annular sealing gasket 8 is embedded in the annular sealing groove. The annular sealing gasket 8 is in sealing contact with the upper end surface of the plug body 3 to achieve sealing of the middle cavity; a sealing gasket 9 is installed between the valve stem 10 and the upper end surface of the valve cover 7, and the sealing gasket 9 and the annular sealing gasket 8 form a double sealing structure for the middle cavity.

[0016] A positioning shaft 15 concentric with the valve stem 10 is provided on the lower end surface of the cock body 3 , and the positioning shaft 15 is inserted into a positioning hole on the upper end surface of the lower cover 16 .

[0017] The inner cavity of the valve body 1, the left half bushing 2, and the right half bushing 5 of the present invention can be fine-machined to achieve higher processing accuracy, and the precision requirement for the valve body casting is lower. This solves the problem that the anti-rotation ribs in the inner cavity of the valve body in the prior art are difficult to process and the precision requirement for the valve body casting is high. This reduces the production cost of the valve body casting, improves the matching accuracy between the valve body, bushing, and plug body, and improves product performance.

[0018] When the flexible non-metallic sealing ring 13 and the rubber sealing ring 17 of the present invention adopt metal sealing rings, they can be used in high-temperature medium working conditions, and these changes should fall within the protection scope of the present invention.

Claims

1. A plug valve with elastic automatic compensating seal, comprising a valve body (1), a valve cover (7), a plug body (3), a valve stem (10), and a transmission mechanism (11), wherein the valve body (1) has a tapered cylindrical cavity and an inlet and outlet passage communicating with the tapered cylindrical cavity, the plug body (3) is a tapered cylindrical body cooperating with the tapered cylindrical cavity, a flow channel hole cooperating with the inlet and outlet passage of the valve body (1) is provided in the plug body (3), and a bushing is provided between the plug body (3) and the tapered cylindrical cavity of the valve body (1); wherein: The bushing is composed of a left bushing (2) and a right bushing (5) located on the left and right sides of the center line of the valve stem (10). The left bushing (2) and the right bushing (5) are respectively provided with flow holes of the same size and shape as the flow holes of the plug body (3). The left bushing (2) and the right bushing (5) are press-fitted into the conical cylindrical cavity of the valve body (1) through the valve cover (7) on the upper end surface. There is a gap between the facing end surfaces of the left bushing (2) and the right bushing (5). The outer cylindrical surfaces of the left bushing (2) and the right bushing (5) and the conical cylindrical cavity of the valve body (1) are spaced apart from each other. The inner cylindrical surfaces of the left half bushing (2) and the right half bushing (5) are embedded with a flexible non-metallic sealing ring (13) concentric with the flow channel hole, and the sealing surface of the flexible non-metallic sealing ring (13) and the plug body (3) protrudes from the inner cylindrical surfaces of the left half bushing (2) and the right half bushing (5); the middle positions of the upper end surfaces of the left half bushing (2) and the right half bushing (5) are respectively provided with an anti-rotation groove (18), and an anti-rotation block (6) is provided on the valve cover (7) directly above the anti-rotation groove (18), and the anti-rotation block (6) is embedded in the anti-rotation groove (18).

2. The plug valve with elastic automatic compensating seal according to claim 1 is characterized in that: Spring grooves are respectively formed on the outer circumferences of the flow hole of the outer cylindrical surface of the left half bushing (2) and the right half bushing (5), and a disc spring (12) is installed between the spring groove and the inner wall of the tapered cylindrical cavity of the valve body (1); a left convex ring (4) and a right convex ring (14) are respectively provided on the outer cylindrical surface of the left half bushing (2) and the right half bushing (5) surrounding the flow hole, and grooves for dynamic sealing with the left convex ring (4) and the right convex ring (14) are respectively formed on the inner wall of the tapered cylindrical cavity on the outer circumference of the flow hole of the inlet and outlet channels of the valve body (1), and a rubber sealing ring (17) is provided between the outer ring surfaces of the left convex ring (4) and the right convex ring (14) and the outer groove walls of the grooves that cooperate with each other.

3. The plug valve with elastic automatic compensating seal according to claim 1 or 2, characterized in that: The lower end surface of the valve cover (7) is provided with an annular sealing groove which is concentric with the valve stem mounting hole. An annular sealing gasket (8) is embedded in the annular sealing groove. The annular sealing gasket (8) is in sealing contact with the upper end surface of the plug body (3). A sealing gasket (9) is installed between the valve stem (10) and the upper end surface of the valve cover (7). The sealing gasket (9) and the annular sealing gasket (8) form a double sealing structure of the middle cavity.

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