Gate valve

Abstract

To provide a gate valve for allowing the replacement of an O-ring which seals a space from a shaft portion located on the opposite side to a valve chest of a flange part of a valve rod, while being put in a water feeding state.SOLUTION: A gate valve 1 includes an O-ring 55 for sealing a space between a supported part 22 of a valve rod 2 and a supporting part 7 of a housing 10, and a large-diameter O-ring 62, the O-ring 55 being laid between a first shaft portion 33 located on the opposite side to a valve chest 5 of a flange part 32 in a shaft part 31 of the valve rod 2 and a first annular inner peripheral face 41 of the supporting part 7, the large-diameter O-ring 62 being laid between the flange part 32 of the valve rod 2 and an annular inner peripheral face 42 of the supporting part 7, the large-diameter O-ring 62 being held by a housing body 65 including the second annular inner peripheral face 42, the O-ring 55 being held by an annular member 66 including the first annular inner peripheral face 41, the annular member 66 being detachably mounted to the housing body 65.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gate valve in which an O-ring seals between a valve stem and a housing that supports the valve stem. [Background technology]

[0002] Such a gate valve is described in Patent Document 1. The gate valve in this document has a valve disc and a valve stem. The valve disc is attached to the valve stem via a screw mechanism. The screw mechanism has a male thread on the valve stem and a female thread on the valve disc. The gate valve also has a housing that includes a valve chamber in which the valve disc is housed, a flow path that passes through the valve chamber, a support part that rotatably supports the valve stem outside the valve chamber, and a guide that prevents the valve disc from rotating together with the valve stem. The guide is located within the valve chamber. When the valve stem is rotated, the valve disc moves along the axis of the valve stem between an open position that opens the flow path and a closed position that closes the flow path.

[0003] In this document, the valve stem includes, in that order, a protruding portion that protrudes into the valve chamber, a supported portion located on the inner periphery of the support portion, and an exposed portion that is exposed to the outside of the housing. The protruding portion includes a male thread of the screw mechanism. The supported portion includes a shaft portion and a flange portion that extends from the middle of the shaft portion toward the outer periphery. In contrast, the support portion of the housing includes an annular inner periphery surface that faces the flange portion from the radial outside. It also includes a first opposing surface that faces the flange portion from the side opposite the valve chamber, and a second opposing surface that faces the flange portion from the valve chamber side. The first opposing surface restricts movement of the valve stem toward the side opposite the valve chamber. The second opposing surface restricts movement of the valve stem toward the valve chamber. The support portion of the housing includes, on the opposite side of the annular inner periphery from the valve chamber, a non-valve chamber-side annular inner periphery surface that faces from the radial outside the non-valve chamber-side axial portion of the shaft portion located on the opposite side of the flange from the valve chamber, and a valve chamber-side annular inner periphery surface that faces from the radial outside the valve chamber-side axial portion of the shaft portion located on the valve chamber side of the flange. The annular inner surface opposite the valve chamber is provided with multiple annular grooves. Each annular groove holds an O-ring. Each O-ring seals the gap between the valve stem and the support, preventing water flowing through the gate valve from leaking between the valve stem and the housing.

[0004] The housing in this document includes a main body member having a flow path, a valve chamber, and a guide, a cover member placed on the main body member from the side opposite the valve chamber, and an annular member held inside the cover member. The cover member is fixed to the main body member with bolts. With the cover member fixed to the main body member, the annular member is located in a space surrounded by the main body member and the second annular member in the axial direction. The main body member has a valve-chamber-side facing surface and a valve-chamber-side annular inner circumferential surface. The cover member has an annular inner circumferential surface facing the flange portion. The annular member has a non-valve-chamber-side facing surface and a valve-chamber-side annular inner circumferential surface, and an O-ring is held in an annular groove provided in the valve-chamber-side annular inner circumferential surface. The first annular inner circumferential surface is the inner circumferential surface of the annular member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-200031 Summary of the Invention [Problem to be solved by the invention]

[0006] In a gate valve, the valve stem is rotated multiple times when the valve disc is moved between the open and closed positions. Therefore, when the gate valve is repeatedly opened and closed, the O-ring that seals between the valve stem and the housing wears out due to the sliding of the valve stem.

[0007] If water leaks from between the valve stem and the housing due to wear of the O-ring, the O-ring must be replaced. Here, in the stop valve of Patent Document 1, when replacing the O-ring, the valve disc is first placed in the closed position to stop water flow through the gate valve. Next, the bolts are removed and the cover member is removed from the main body member. After that, the O-ring is removed from the annular groove provided on the inner circumferential surface (the annular inner circumferential surface opposite the valve chamber) of the annular member held inside the cover member. After that, a new O-ring is installed in the annular groove, the cover member is placed over the main body member, and the bolts are tightened. This completes the housing. After that, the valve disc is placed in the open position to allow water to flow through the gate valve.

[0008] However, stopping the flow of water through the gate valve to replace the O-ring poses a problem: the piping passing through the gate valve is cut off. However, if you attempt to replace the O-ring while water is still flowing through the gate valve, the pressure of the water flowing through the gate valve causes water to forcefully gush out from between the flange portion of the valve stem and the valve chamber-facing surface of the body member when you remove the cover member from the body member. Furthermore, when you fasten the cover member holding the annular member to the body member after replacing the O-ring, the pressure of the water flowing into the cover member through the gap between the body member and the valve stem causes the O-ring held by the annular member to protrude significantly from the annular groove. Therefore, when attaching the cover member to the body member, it is difficult to maintain the same sealing condition of the O-ring that sealed between the valve stem and the housing as before the replacement.

[0009] In view of these points, the object of the present invention is to provide a check valve in which the O-ring that seals between the shaft portion of the valve stem located on the opposite side of the flange portion from the valve chamber and the housing can be replaced while water is still flowing through. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a gate valve comprising: a valve stem; a valve disc attached to the valve stem via a screw mechanism and movable along the axis of the valve stem; a valve chamber in which the valve disc is accommodated; a flow path passing through the valve chamber; an annular support part rotatably supporting the valve stem from the outside in the radial direction outside the valve chamber; and a housing having a rotation restricting part restricting the valve disc from rotating together with the valve stem; wherein the valve disc moves between an open position in which the flow path is opened and a closed position in which the flow path is closed by rotation of the valve stem; the gate valve comprises a first O-ring and a second O-ring sealing between the valve stem and the support part; the valve stem comprises, in this order along the axis, a protruding part protruding into the valve chamber; a supported part located on the inner periphery of the support part; and an exposed part exposed to the outside of the housing; the supported part comprises a shaft part and a flange part extending radially outward from the shaft part; and the support part comprises: When the direction along the axis of the valve stem is defined as the axial direction, the side on which the exposed portion is located is defined as the first axial direction, and the side on which the protruding portion is located is defined as the second axial direction, the valve valve comprises a first annular inner circumferential surface that faces, from the radially outer side, a first shaft portion of the shaft portion that is located in the first direction of the flange portion, and a second annular inner circumferential surface that faces, from the radially outer side, the flange portion in the second direction of the first annular inner circumferential surface, the first O-ring is held in a first annular groove provided on the first annular inner circumferential surface, and the second O-ring is held in a second annular groove provided on the second annular inner circumferential surface, the housing comprises: a housing main body that includes the flow path, the valve chamber, the rotation regulating portion, and the second annular inner circumferential surface; and an annular member that includes the first annular inner circumferential surface, the annular member having a central hole through which the valve stem passes, and is detachably attached to the housing main body in the axial direction.

[0011] The gate valve of the present invention has a first O-ring and a second O-ring that seal the gap between the supported portion of the valve stem and the support portion of the housing. The first O-ring is interposed between a first shaft portion of the shaft portion of the supported portion, which is located on the opposite side of the flange portion from the valve chamber, and the first annular inner circumferential surface of the support portion. The second O-ring is interposed between the flange portion of the supported portion and the second annular inner circumferential surface of the support portion. The first O-ring is held by an annular member detachably attached to the housing body, and the second O-ring is held by the housing body that has the valve chamber. Annular member The valve stem passes through the central hole, and the annular member is detachably attached to the housing body in the axial direction. Therefore, if the first O-ring wears and water leaks from between the valve stem and the housing, the first O-ring can be replaced by removing the annular member axially from the housing body. Even when the annular member is removed axially from the housing body, the second O-ring interposed between the flange portion of the valve stem and the second annular inner surface of the housing body remains sealed between the valve stem and the housing body. Therefore, when the annular member is removed from the housing body, water is prevented from gushing out from between the valve stem and the housing body. Furthermore, because water is prevented from gushing out from between the valve stem and the housing body, water does not flow into the annular member when the annular member is attached to the housing body after replacement. Therefore, when the annular member is attached to the housing body, the first O-ring does not protrude significantly from the first annular groove of the annular member due to water pressure. Therefore, when the annular member is attached to the housing body, the sealing state of the first O-ring that seals between the valve stem and the housing can be made the same as the sealing state before replacement.

[0012] In the present invention, the second O-ring can be thicker in the axial direction and radial direction than the first O-ring. That is, the second O-ring can have a larger inner diameter and be thicker than the first O-ring. This makes it possible to make the second O-ring more wear-resistant than the first O-ring. Therefore, when replacing the first O-ring, it is easy to prevent water from leaking between the valve stem and the housing body.

[0013] In the present invention, a third O-ring may be provided to seal the gap between the valve stem and the support portion, and the third O-ring may be held in a third annular groove provided on the first annular inner peripheral surface in the second direction of the first annular groove. This configuration can more reliably seal the gap between the first shaft portion of the valve stem and the support portion of the housing. Furthermore, the third O-ring is held by the annular member, just like the first O-ring. Therefore, there is no need to stop water flow through the gate valve when replacing the third O-ring.

[0014] In the present invention, the housing body may include a fourth O-ring, the housing body including a cylindrical portion coaxial with the first annular inner peripheral surface in the first direction, the cylindrical portion opening in the first direction and including an annular notched groove at its opening edge, the inner peripheral surface of the cylindrical portion including a female thread in the second direction of the notched groove, the annular member including a male thread that threads into the female thread and a fourth annular groove in the first direction of the male thread, the fourth O-ring being attached to the fourth annular groove, and when the male thread is screwed into the female thread to attach the annular member to the cylindrical portion, the fourth O-ring is inserted into the notched groove to seal between the housing body and the annular member. This makes it easy to attach and detach the annular member from the housing body in the axial direction. Furthermore, this allows the fourth O-ring to seal between the annular member and the housing body. Here, in the present invention, when the annular member is removed axially from the housing body, the gap between the flange portion of the valve stem and the second annular inner circumferential surface of the housing body remains sealed by the second O-ring. Therefore, when the annular member is removed from the housing body to replace the first O-ring, water is prevented from gushing out from between the valve stem and the housing body. Furthermore, when the annular member is attached to the housing body after replacing the first O-ring, water does not forcefully flow into the annular member. Therefore, when the annular member is attached to the housing body, the fourth O-ring attached to the annular member does not protrude significantly from the fourth annular groove due to water pressure. Therefore, when the annular member is attached to the housing body, the sealing state of the fourth O-ring that seals between the annular member and the housing body can be maintained identical to the sealing state before replacement.

[0015] In the present invention, the support portion faces the flange portion from the first direction side. The valve stem may include a first opposing surface that restricts movement of the valve stem in the first direction, and a second opposing surface that opposes the flange portion from the second direction and restricts movement of the valve stem in the second direction, the second opposing surface being provided on the housing main body, and the first opposing surface being provided on the annular member. In this way, movement of the valve stem in the first direction can be restricted by attaching the annular member to the housing main body. This eliminates the need to provide the first opposing surface on the housing main body, making it easy to support a valve stem with a flange portion on a support portion.

[0016] In the present invention, the shaft portion may include, in this order from the flange portion toward the first direction, a large-diameter portion having a constant outer diameter and a small-diameter portion having an outer diameter smaller than the large-diameter portion, the outer diameter of the exposed portion being equal to or smaller than the outer diameter of the small-diameter portion, and the first annular groove being provided on an inner circumferential surface of the first annular surface facing the large-diameter portion. This configuration can prevent the first O-ring from interfering with the side of the valve stem closer to the exposed portion than the large-diameter portion when the annular member is removed from the housing body in the first direction. Furthermore, when a replaced annular member holding a new first O-ring is attached to the housing body from the first direction, the first O-ring can be prevented from interfering with the side of the valve stem closer to the exposed portion than the large-diameter portion.

[0017] In the present invention, a handle can be detachably attached to the exposed portion. Providing a handle makes it easier to rotate the valve stem, facilitating opening and closing of the gate valve. Furthermore, since the handle is detachable from the valve stem, the annular member can be removed from the valve stem by removing the handle from the valve stem. This facilitates replacement of the first O-ring held on the inner circumferential surface of the annular member. [Effects of the Invention]

[0018] According to the present invention, the first O-ring held in the first annular groove can be replaced by axially removing the annular member from the housing body. Furthermore, even when the annular member holding the first O-ring is removed, the second O-ring seals the gap between the valve stem and the housing body. Therefore, the first O-ring can be replaced without stopping water flow through the gate valve. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a partial cross-sectional view of a gate valve in a water-passing state, viewed from a direction perpendicular to the flow path. [Figure 2] 1 is a partial cross-sectional view of a gate valve in a water-passing state, viewed from a direction along the flow path. [Figure 3] FIG. 4 is a partially enlarged view of the periphery of the support portion of the housing and the supported portion of the valve stem. [Figure 4] FIG. 10 is an explanatory diagram showing a state in which the annular member is removed from the housing main body. [Figure 5] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 6] 1 is a partial cross-sectional view of a gate valve in a water-stop state, viewed from a direction perpendicular to the flow path. [Figure 7] 1 is a partial cross-sectional view of a gate valve in a water-stop state as viewed from a direction along the flow path. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A gate valve according to an embodiment of the present invention will be described below with reference to the drawings.

[0021] Figure 1 is a partial cross-sectional view of a gate valve with its valve disc in the open position, viewed from a direction perpendicular to the flow path. Figure 3 is a partial cross-sectional view of a gate valve with its valve disc in the open position, viewed from a direction along the flow path. Figure 4 is a partial cross-sectional view of a gate valve with its valve disc in the closed position, viewed from a direction perpendicular to the flow path. Figure 4 is a partial cross-sectional view of a gate valve with its valve disc in the closed position, viewed from a direction along the flow path. Figure 5 is a cross-sectional view taken along line AA in Figure 1.

[0022] As shown in FIG. 1, the gate valve 1 of this example has a valve stem 2 and a valve element 3. The valve element 3 is attached to the valve stem 2 via a screw mechanism 4. The valve element 3 is movable along the axis L of the valve stem 2. The gate valve 1 also has a housing 10 equipped with a valve chamber 5 in which the valve element 3 is housed, a flow path 6 passing through the valve chamber 5, an annular support portion 7 that rotatably supports the valve stem 2 from the radially outer side outside the valve chamber 5, and a rotation restricting portion 8 that restricts the valve element 3 from rotating together with the valve stem 2. The flow path 6 extends in a direction perpendicular to the axis L of the valve stem 2. A first ball plunger 11 and a second ball plunger 12 (see Figure 5) are held in the housing 10.

[0023] (Stem and disc) As shown in Figures 1 and 2, the valve stem 2 includes a protruding portion 21 that protrudes into the valve chamber 5, a supported portion 22 located on the inner periphery of the support portion 7, and an exposed portion 23 that is exposed outside the housing 10, in this order along the axis L. The protruding portion 21 is provided with a male thread 21a. In the following description, the direction along the axis L of the valve stem 2 is referred to as the axial direction X. The side on which the exposed portion 23 is located is referred to as the first direction X1 of the axial direction X, and the side on which the protruding portion 21 is located is referred to as the second direction X2 of the axial direction X. The second direction X is the side on which the flow path 6 is located in the housing 10. The direction in which the flow path 6 extends is referred to as the extension direction Y. The axial direction X and the extension direction Y are perpendicular to each other. The direction perpendicular to the axial direction X and the extension direction Y is referred to as the orthogonal direction Z.

[0024] Here, the valve element 3 includes a closing portion 25 that closes the flow path 6, an extension portion 26 that extends from the closing portion 25 in the first direction X1, and an axial hole 27 that penetrates the closing portion 25 and the extension portion 26 in the axial direction X. An internal thread 27a is provided on the inner peripheral surface of the axial hole 27 in the extension portion 26. The valve element 3 is attached to the valve rod 2 with the valve rod 2 passing through the axial hole 27 and the internal thread 27a screwed onto the external thread 21a of the protruding portion 21. The external thread 21a and the internal thread 27a constitute the screw mechanism 4. The outer peripheral surface of the valve element 3 is covered with a sealing material 28.

[0025] The supported portion 22 of the valve stem 2 includes a shaft portion 31 and a flange portion 32 extending radially outward from the middle of the shaft portion 31. As shown in FIG. 3, the shaft portion 31 includes a first shaft portion 33 (shaft portion) located in the first direction X1 of the flange portion 32 and a second shaft portion 34 located in the second direction X2 of the flange portion 32. The first shaft portion 33 includes, from the flange portion 32 toward the first direction X1, a large diameter portion 35 having a constant outer diameter and a small diameter portion 36 having an outer diameter smaller than that of the large diameter portion 35, in this order. As shown in FIG. 5, the small diameter portion 36 is provided with a first locking recess 37(1) and a second locking recess 37(2) at positions spaced 180° apart in the circumferential direction. A third locking recess 37(3) and a fourth locking recess 37(4) are provided at the circumferential centers of the first locking recess 37(1) and the second locking recess 37(2). Therefore, the locking recesses 37(1) to 37(4) are provided around the axis L at equal angular intervals.

[0026] The outer diameter of the exposed portion 23 is equal to or smaller than the outer diameter of the small diameter portion 36. A handle 39 is detachably attached to the end of the exposed portion 23 in the first direction X1.

[0027] (housing) As shown in FIGS. 1 and 2 , the flow path 6 is provided at an end portion of the housing 10 in the second direction X2. The valve chamber 5 extends in the first direction X1 from a position overlapping with the flow path 6. The support portion 7 is provided in the first direction X1 of the valve chamber 5. As shown in FIG. 3 , the support portion 7 includes a first annular inner circumferential surface 41 facing the first shaft portion 33 of the shaft portion 31 from the radially outer side, a second annular inner circumferential surface 42 facing the flange portion 32 from the radially outer side in the second direction X2 of the first annular inner circumferential surface 41, and a third annular inner circumferential surface 43 facing the second shaft portion 34 of the shaft portion 31 from the radially outer side in the second direction X2 of the second annular inner circumferential surface 42. The first annular inner circumferential surface 41, the second annular inner circumferential surface 42, and the third annular inner circumferential surface 43 are coaxial. The support portion 7 also includes a first opposing surface 44 that faces the flange portion 32 from the first direction X1 side, and a second opposing surface 45 that faces the flange portion 32 from the second direction X2 side. The first opposing surface 44 restricts movement of the valve stem 2 in the first direction X1. The second opposing surface 45 restricts movement of the valve stem 2 in the second direction X2.

[0028] Furthermore, the support portion 7 is provided with a first retaining portion 47 that retains the first ball plunger 11 and a second retaining portion 48 that retains the second ball plunger 12 at its end portions in the first direction X1. The first retaining portion 47 and the second retaining portion 48 are each a through hole that passes through the support portion 7 in the radial direction. In this example, the first retaining portion 47 and the second retaining portion 48 are provided at angular positions that are 180° apart. Female threads 47a and 48a are provided on the inner circumferential surfaces of the first retaining portion 47 and the second retaining portion 48, respectively.

[0029] The first annular inner circumferential surface 41 includes a large-diameter inner circumferential surface portion 51 (inner circumferential surface portion) that faces the large-diameter portion 35 of the first shaft portion 33 from the radially outer side, and a small-diameter inner circumferential surface portion 52 that faces the small-diameter portion 36 of the first shaft portion 33 from the radially outer side in the first direction X1 of the large-diameter inner circumferential surface portion 51. The large-diameter inner circumferential surface portion 51 is provided with two annular grooves 53, 54 that are spaced apart in the axial direction X. The annular groove 54 (third annular groove) is located in the second direction X2 of the annular groove 53 (first annular groove). The annular groove 53 holds an O-ring 55 (first O-ring). The annular groove 54 holds an O-ring 56 (third O-ring). The O-rings 55, 56 seal between the support portion 7 of the housing 10 and the large-diameter portion 35 of the first shaft portion 33 of the valve stem 2.

[0030] An opening on the inner periphery of the first retaining portion 47 and an opening on the inner periphery of the second retaining portion 48 are exposed in the small-diameter inner circumferential surface portion 52. As shown in FIG. 5 , the first retaining portion 47 holds the first ball plunger 11 in a position where the ball 11a protrudes from the opening into the central hole of the support portion 7. The second retaining portion 48 holds the second ball plunger 12 in a position where the ball 12a protrudes from the opening into the central hole of the support portion 7. Here, the first ball plunger 11 has a male thread 11b on its outer periphery that can be threaded into the female thread 47a. The second ball plunger 12 has a male thread 12b on its outer periphery that can be threaded into the female thread 48a. Each ball plunger 11, 12 is fixed to the support portion 7 by being screwed into each retaining portion 47, 48 from the radially outer side.

[0031] Additionally, an annular groove 58 is provided in the small diameter inner circumferential surface portion 52 in the first direction X1 between the opening of the first retaining portion 47 and the opening of the second retaining portion 48. An O-ring 59 is held in the annular groove 58. The O-ring 59 seals the gap between the small diameter inner circumferential surface portion 52 of the support portion 7 and a portion of the small diameter portion 36 of the valve stem 2 that is closer to the first direction X1 than the locking recesses 37(1) to 37(4).

[0032] The second annular inner circumferential surface 42, which faces the flange portion 32, has a larger inner diameter than the first annular inner circumferential surface 41 and the third annular inner circumferential surface 43. A large-diameter annular groove 61 (second annular groove) is provided in the second annular inner circumferential surface 42. A large-diameter O-ring 62 (second O-ring) is held in the large-diameter annular groove 61. The large-diameter annular groove 61 is wider in the axial direction X and deeper in the radial direction than the annular grooves 53, 54 provided in the first annular inner circumferential surface 41. The large-diameter O-ring 62 has a larger inner diameter than the O-rings 55, 56 and is thicker in the axial direction X and radial directions than the O-rings 55, 56. The large-diameter O-ring 62 radially seals the gap between the flange portion 32 of the valve stem 2 and the support portion 7 of the housing 10.

[0033] The rotation restricting portion 8 is a protrusion provided on the inner wall surface of the valve chamber 5 in the housing 10. The rotation restricting portion 8 contacts both end edges of the valve element 3 in the orthogonal direction Z, restricting the valve element 3 from rotating together with the valve stem 2. Therefore, when the valve stem 2 rotates, the valve element 3 moves in the axial direction X of the valve stem 2.

[0034] 1 and 2, the housing 10 includes a housing main body 65 having therein a flow path 6, a valve chamber 5, and a rotation restricting portion 8, and an annular member 66 detachably attached to the housing main body 65. The valve stem 2 passes through a central hole of the annular member 66.

[0035] The housing body 65 also includes a body member 67 having the flow passage 6, and a cover member 68 that covers the body member 67 from the side in the first direction X1. The cover member 68 is secured by four bolts 69. Thus, it is fastened to the main body member 67. Between the main body member 67 and the cover member 68, the valve chamber 5 is defined.

[0036] As shown in Fig. 4, the cover member 68 has a cylindrical portion 71 at an end portion in the first direction X1. The cylindrical portion 71 opens in the first direction X1. An annular notched groove 72 is provided at the edge of the opening of the cylindrical portion 71. An internal thread 71a is provided on the inner peripheral surface of the cylindrical portion 71 in the second direction X2 of the notched groove 72.

[0037] As shown in FIGS. 4 and 5 , the annular member 66 includes a plate portion 75 having a substantially hexagonal outline when viewed from the axial direction X, a substantially rectangular parallelepiped protruding portion 76 protruding in the first direction X1 from the center of the plate portion 75, and a cylindrical portion 77 protruding in the second direction X2 from the plate portion 75. The cylindrical portion 77 includes an external thread 77a on its outer circumferential surface that is threadedly engaged with an internal thread 71a of the tubular portion 71 of the cover member 68. The cylindrical portion 77 also includes an annular groove 74 (fourth annular groove) on its outer circumferential surface, extending in the first direction X1 from the external thread 77a. The annular groove 74 is located between the external thread 77a and the plate portion 75. The annular groove 74 protrudes radially outward from a position adjacent to the plate portion 75 in the second direction X2. An O-ring 73 (fourth O-ring) is attached to the annular groove 74.

[0038] The protruding portion 76 is provided with a first retaining portion 47 and a second retaining portion 48 on either side of the center hole of the annular member 66. The first ball plunger 11 is screwed into the first retaining portion 47 from one side in the extension direction Y. The second ball plunger 12 is screwed into the second retaining portion 48 from the other side in the extension direction Y.

[0039] The annular member 66 is attached to the housing main body 65 by screwing the cylindrical portion 77 into the tubular portion 71 from the side in the first direction X1. In this example, when the cylindrical portion 77 is attached to the housing main body 65, the longitudinal direction of the protruding portion 76 faces the extension direction Y of the flow path 6. When the annular member 66 is attached to the housing main body 65, the longitudinal direction of the protruding portion 76 may face in a direction different from the extension direction Y. Here, when the annular member 66 is fixed to the cover member 68, the O-ring 73 attached to the annular groove 74 of the annular member 66 is interposed between the tubular portion 71 and the cylindrical portion 77 with its outer periphery inserted into the cutout groove 72 of the tubular portion 71. In this way, the O-ring 73 seals the gap between the annular member 66 and the cover member 68. Furthermore, when the annular member 66 is fixed to the lid member 68, the plate portion 75 located adjacent to the annular groove 74 in the first direction X1 covers the cylindrical portion 77 from the first direction X1 side and comes into contact with the cylindrical portion 77. As a result, the O-ring 73 abuts against the plate portion 75 and is elastically deformed, thereby sealing the gap between the plate portion 75 and the lid member 68.

[0040] The annular member 66 is fixed to the cover member 68 by a fixing screw 79 (see FIG. 2) that penetrates the plate portion 75 in the axial direction X and is screwed into the end face of the cylindrical portion 71 in the first direction X1.

[0041] Here, the support portion 7 of the housing 10 is composed of a cover member 68 and an annular member 66. That is, the cover member 68 has a second annular inner circumferential surface 42, a third annular inner circumferential surface 43, and a second opposing surface 45. The annular member 66 has a first retaining portion 47, a second retaining portion 48, a first annular inner circumferential surface 41, and a first opposing surface 44.

[0042] (Opening and closing of gate valve) Figure 6 is a partial cross-sectional view of the gate valve 1 with the valve element 3 in the open position, viewed from a direction perpendicular to the flow path 6. Figure 7 is a partial cross-sectional view of the gate valve 1 with the valve element 3 in the open position, viewed from a direction along the flow path 6. The gate valve 1 is installed in the middle of a pipe through which water flows. In this example, it is installed in the middle of a fire protection pipe that distributes water stored in a fire water tank.

[0043] When an operator operates the handle 39 to rotate the valve stem 2, the valve element 3 opens the flow path 6. The valve shaft 2 moves along the axis L of the valve rod 2 between an open position 3A (see Figures 1 and 3) where the flow path 6 is open, and a closed position 3B (see Figures 6 and 7) where the flow path 6 is closed. In the open position 3A, the valve disc 3 moves away from the bottom 5a of the valve chamber 5 in the first direction X1 and abuts against the ceiling 5b of the valve chamber 5. This puts the gate valve 1 into a water-permeable state, allowing water to flow through the piping. In the closed position 3B, the valve disc 3 abuts against the bottom 5a of the valve chamber 5. This puts the gate valve 1 into a water-stopping state, cutting off water flow through the piping.

[0044] Here, the gate valve 1 holds ball plungers 11 and 12 in the housing 10. The outer peripheral surface of the valve stem 2 is provided with locking recesses 37(1) to 37(4) into which the balls 11a and 12a of the ball plungers 11 and 12 can be locked. The ball plungers 11 and 12 simultaneously lock into two of the locking recesses 37(1) to 37(4). Therefore, an operator of the gate valve 1 who rotates the valve stem 2 can feel a clicking sensation each time the ball plungers 11 and 12 lock into one of the locking recesses 37(1) to 37(4). Therefore, the operator can determine the number of rotations of the valve stem 2 based on the number of clicks felt. This allows the operator to avoid excessive rotation of the valve stem 2 after the valve disc 3 is positioned in the closed position 3B, which could damage the valve stem 2, the valve disc 3, or the screw mechanism 4.

[0045] (Replacing the O-ring) In the gate valve 1, the valve stem 2 is rotated multiple times when the valve disc 3 is moved between the open position 3A and the closed position 3B. Therefore, when the gate valve 1 is repeatedly opened and closed, the O-rings 55, 56 that seal between the first shaft portion 33 of the valve stem 2 and the support portion 7 of the housing 10 are worn due to the sliding of the valve stem 2. If water leaks from between the valve stem 2 and the housing 10 due to wear of the O-rings 55, 56, the O-rings 55, 56 must be replaced.

[0046] When replacing the O-rings 55, 56, first, with the valve disc 3 in the open position 3A, remove the handle 39 from the valve stem 2. Next, remove the fixing screw 79. After that, remove the annular member 66 screwed into the cylindrical portion 71 from the housing main body 65 in the first direction X1. Furthermore, remove the annular member 66 from the valve stem 2 in the first direction X1. The state after removing the annular member 66 is shown in Figure 4. This exposes the inner circumferential surface (first annular inner circumferential surface 41) of the annular member 66 to the outside, allowing the O-rings 55, 56 held in the annular grooves 53, 54 to be removed.

[0047] In this example, the housing main body 65 (lid member 68) has a tubular portion 71 that is coaxial with the first annular inner circumferential surface 41 in the first direction X1 of the first annular inner circumferential surface 41. The tubular portion 71 opens in the first direction X1 and has a female thread 71a on its inner wall surface. The annular member 66 has a male thread 66a that screws into the female thread 71a, and is detachably attached to the tubular portion 71. Therefore, the annular member 66 can be easily removed from the housing main body 65 in the axial direction X.

[0048] Here, the gate valve 1 has O-rings 55, 56 and a large-diameter O-ring 62 that seal the gap between the supported portion 22 of the valve stem 2 and the support portion 7 of the housing 10. The large-diameter O-ring 62 is held in the housing body 65 in the second direction X2 (toward the valve chamber 5) relative to the O-rings 55, 56. Therefore, even when the annular member 66 that holds the O-rings 55, 56 is removed from the housing body 65 in the axial direction X, the large-diameter O-ring 62 interposed between the flange portion 32 of the valve stem 2 and the second annular inner circumferential surface 42 of the housing body 65 remains sealed between the valve stem 2 and the housing body 65. Therefore, when the annular member 66 is removed from the housing body 65, water flowing through the valve chamber 5 can be prevented from gushing out from between the valve stem 2 and the housing body 65.

[0049] The first shaft portion 33 is provided with, in order from the flange portion 32 in the first direction X1, a large diameter portion 35 having a constant outer diameter and a small diameter portion 36 having an outer diameter smaller than that of the large diameter portion 35. The outer diameter of the exposed portion 23 is equal to or smaller than that of the small diameter portion 36. An O-ring 55, The annular grooves 53, 54 that hold the O-rings 55, 56 are provided in the large-diameter inner circumferential surface portion 51 that faces the large-diameter portion 35 on the first annular inner circumferential surface 41. Therefore, when the annular member 66 is removed in the first direction X1 from the housing main body 65, it is possible to prevent the O-rings 55, 56 from interfering with the portion of the valve stem 2 that is closer to the first direction X1 than the large-diameter portion 35 (the small-diameter portion 36 and the exposed portion 23).

[0050] Next, new O-rings 55, 56 are held in the annular grooves 53, 54 of the annular member 66. After that, with the valve stem 2 passing through the center hole of the annular member 66, the annular member 66 is screwed into the cylindrical portion 71 of the housing main body 65. After that, the annular member 66 is fixed to the housing main body 65 with the fixing screws 79.

[0051] Here, in this example, when the annular member 66 is removed from the housing body 65, water does not forcefully gush out from between the valve stem 2 and the housing body 65. Therefore, when the annular member 66 is attached to the housing body 65 after replacing the O-rings 55, 56, water does not forcefully flow toward the annular member 66. Therefore, when the annular member 66 is attached to the housing body 65, water pressure does not cause the O-rings 55, 56 to protrude significantly from the annular grooves 53, 54 of the annular member 66. Furthermore, when the annular member 66 is attached to the housing body 65, water pressure does not cause the O-rings 73 attached to the outer peripheral surface of the annular member 66 to protrude significantly from the annular groove 74 of the annular member 66. Therefore, when the annular member 66 is attached to the housing body 65, the sealing state of the O-rings 55, 56 that seal between the valve stem 2 and the housing 10 can be maintained at the same sealing state as before replacement.

[0052] Furthermore, the outer diameter of the valve stem 2 in the first direction X1 is smaller than the outer diameter of the large diameter portion 35 of the valve stem 2. Therefore, when attaching the annular member 66 that holds new O-rings 55, 56 to the housing main body 65 from the first direction X1 side, it is possible to prevent the O-rings 55, 56 from interfering with the portion of the valve stem 2 that is closer to the first direction X1 than the large diameter portion 35.

[0053] Furthermore, the annular member 66 has a male thread 77a that screws into the female thread 71a, and is detachably attached to the cylindrical portion 71. Therefore, the annular member 66 that holds the O-rings 55, 56 can be easily attached to the housing main body 65 from the side in the first direction X1.

[0054] (Action and effect) According to this example, when the annular member 66 is removed from the housing body 65 in the axial direction X, the water flowing through the valve chamber 5 does not forcefully spurt out from between the valve stem 2 and the housing body 65. Therefore, the gate valve 1 of this example can replace the O-rings 55, 56 while the water is still flowing. Therefore, according to this example, the piping connected to the fire water tank is not cut off when replacing the O-rings 55, 56.

[0055] Furthermore, in this example, the large-diameter O-ring 62 is thicker in the axial direction X and radial direction than the O-rings 55, 56. That is, the large-diameter O-ring 62 has a larger inner diameter than the O-rings 55, 56 and is thicker than the O-rings 55, 56. This makes it easy to make the wear resistance of the large-diameter O-ring 62 greater than the wear resistance of the O-rings 55, 56. Therefore, it is easy to prevent water from leaking between the valve stem 2 and the housing body 65 when replacing the O-rings 55, 56.

[0056] Furthermore, this example has two O-rings 55, 56 that seal between the first shaft portion 33 of the valve stem 2 and the support portion 7 of the housing 10. This makes it possible to more reliably seal between the valve stem 2 and the housing 10. Furthermore, since these two O-rings 55, 56 are held by the annular member 66, they can be easily replaced.

[0057] In this example, the support portion 7 faces the flange portion 32 from the first direction X1 side and supports the valve stem 2. The valve stem 2 includes a first opposing surface 44 that restricts movement of the valve stem 2 in the first direction X1, and a second opposing surface 45 that opposes the flange portion 32 from the second direction X2 side and restricts movement of the valve stem 2 in the second direction X2. The second opposing surface 45 is provided on the housing main body 65, and the first opposing surface 44 is provided on the annular member 66. Therefore, by attaching the annular member 66 to the housing main body 65, movement of the valve stem 2 in the first direction X1 can be restricted. This eliminates the need to provide the first opposing surface 44 on the housing main body 65, making it easy to support the valve stem 2 with the flange portion 32 on the support portion 7.

[0058] In this example, an annular notched groove 72 is provided on the opening edge of the tubular portion 71 of the housing main body 65. A female thread 71a is provided on the inner peripheral surface of the tubular portion 71 in the second direction X2 of the notched groove 72. The annular member 66 has a male thread 77a on the cylindrical portion 77 that screws into the female thread 71a, and an annular groove 74 on the outer peripheral surface between the male thread 77a and the plate portion 75. An O-ring 73 is attached to the annular groove 74. Therefore, when the annular member 66 is attached to the cover member 68, the O-ring 73 attached to the annular groove 74 of the annular member 66 is interposed between the tubular portion 71 and the cylindrical portion 77 with its outer peripheral side inserted into the notched groove 72 of the tubular portion 71. This allows the O-ring 73 to seal the gap between the annular member 66 and the cover member 68.

[0059] Furthermore, in this example, the gate valve 1 has a handle 39 detachably attached to the exposed portion 23. This makes it easy to rotate the valve stem 2, thereby facilitating opening and closing of the gate valve 1. Also, because the handle 39 is detachable from the valve stem 2, the annular member 66 can be removed from the valve stem 2 by removing the handle 39 from the valve stem 2. This makes it easy to replace the O-rings 55, 56 held by the annular member 66. [Explanation of symbols]

[0060] 1...gate valve, 2...valve stem, 3...valve disc, 3A...open position, 3B...closed position, 4...screw mechanism, 5...valve chamber, 5a...bottom of valve chamber, 5b...ceiling of valve chamber, 6...flow path, 7...support portion, 7a...center hole of support portion, 8...rotation restriction portion, 10...housing, 11...first ball plunger, 11a...ball, 12...second ball plunger, 12a...ball, 21...protruding portion, 22... Supported portion, 23...exposed portion, 25...blocking portion, 26...extension portion, 27...shaft hole, 28...sealing material, 31...shaft portion, 32...flange portion, 33...first shaft portion, 34...second shaft portion, 35...large diameter portion, 36...small diameter portion, 37...engaging recess, 39...handle, 41...first annular inner circumferential surface, 42...second annular inner circumferential surface, 43...third annular inner circumferential surface, 44...first opposing surface, 45...second opposing surface, 47...first retaining portion, 48...second retaining portion, 51...large diameter inner peripheral surface portion, 52...small diameter inner peripheral surface portion, 53...annular groove (first annular groove), 54...annular groove (third annular groove), 55...O-ring (first O-ring), 56...O-ring (third O-ring), 58...annular groove, 59...O-ring, 61...large diameter annular groove (second annular groove), 62...large diameter O-ring (second O-ring), 65 ...Housing body, 66...Annular member, 66a...Center hole of annular member, 67...Main body member, 68...Cover member, 69...Bolt, 71...Cylindrical portion, 72...Notched groove (fourth annular groove), 73...O-ring (fourth O-ring), 74...Annular groove (fourth annular groove), 75...Plate portion, 76...Protrusion portion, 77...Cylindrical portion, L...Axis of valve stem, X...Axial direction, Y...Extension direction of flow path, Z...Orthogonal direction

Claims

1. a valve stem; a valve disc attached to the valve stem via a screw mechanism and movable along the axis of the valve stem; a valve chamber accommodating the valve disc; a flow path passing through the valve chamber; an annular support portion rotatably supporting the valve stem from the outside in the radial direction outside the valve chamber; and a rotation restricting portion restricting the valve disc from rotating together with the valve stem, wherein the valve disc moves between an open position that opens the flow path and a closed position that closes the flow path in response to rotation of the valve stem, a first O-ring and a second O-ring sealing between the valve stem and the support; the valve stem includes, in this order along the axis, a protruding portion that protrudes into the valve chamber, a supported portion that is located on the inner circumferential side of the support portion, and an exposed portion that is exposed to the outside of the housing, The supported portion includes a shaft portion and a flange portion extending outward from the shaft portion, When a direction along the axis of the valve stem is defined as an axial direction, a side on which the exposed portion is located is defined as a first axial direction, and a side on which the protruding portion is located is defined as a second axial direction, the support portion comprises: a first annular inner circumferential surface that faces, from the radially outer side, a first shaft portion of the shaft portion that is located in the first direction of the flange portion; and a second annular inner circumferential surface that faces, from the radially outer side, the flange portion in the second direction of the first annular inner circumferential surface, the first O-ring is held in a first annular groove provided in the first annular inner circumferential surface, the second O-ring is held in a second annular groove provided in the second annular inner circumferential surface, the housing includes a housing main body including the flow path, the valve chamber, the rotation restricting portion, and the second annular inner circumferential surface, and an annular member including the first annular inner circumferential surface, A gate valve characterized in that the annular member has a central hole through which the valve stem passes and is detachably attached to the housing body in the axial direction.

2. 2. The gate valve according to claim 1, wherein the second O-ring is thicker than the first O-ring in the axial direction and the radial direction.

3. a third O-ring sealing between the valve stem and the support; 3. A gate valve as described in claim 1 or 2, characterized in that the third O-ring is held in a third annular groove provided in the first annular inner surface in the second direction of the first annular groove.

4. a fourth O-ring; the housing main body includes a cylindrical portion coaxial with the first annular inner circumferential surface in the first direction of the first annular inner circumferential surface, the cylindrical portion is open in the first direction and has an annular notched groove on an edge of the opening; an inner circumferential surface of the cylindrical portion is provided with a female thread in the second direction of the notched groove; the annular member has a male thread that screws into the female thread, and a fourth annular groove in the first direction of the male thread; A check valve described in any one of claims 1 to 3, characterized in that the fourth O-ring is attached to the fourth annular groove, and when the male thread is screwed into the female thread and the annular member is attached to the tubular portion, its outer side is inserted into the notched groove to seal the space between the housing body and the annular member.

5. The support portion includes a first opposing surface that faces the flange portion from the first direction side and restricts movement of the valve stem in the first direction, and a second opposing surface that faces the flange portion from the second direction side and restricts movement of the valve stem in the second direction, the second opposing surface is provided on the housing main body, The gate valve according to claim 4, wherein the first opposing surface is provided on the annular member.

6. the shaft portion includes, in this order from the flange portion toward the first direction, a large diameter portion having a constant outer diameter dimension and a small diameter portion having an outer diameter dimension smaller than that of the large diameter portion; an outer diameter dimension of the exposed portion is equal to or smaller than an outer diameter dimension of the small diameter portion; A gate valve according to any one of claims 1 to 5, characterized in that the first annular groove is provided in an inner surface portion of the first annular inner surface facing the large diameter portion.

7. 7. A gate valve according to claim 1, further comprising a handle removably attached to the exposed portion.

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