Gate valve

Abstract

To provide a gate valve which can make fluid flow at a large flow rate even if the valve in the middle of a stroke (in a state that a part of a valve body blocks a linear flow passage).SOLUTION: A gate valve (10) comprises a valve box (14), a linear flow passage (12) formed in the valve box (14), a valve body (16) displaceable in an axial direction vertical to the flow passage (12), and capable of blocking the flow passage (12) by abutting on an inner wall (12a) of the flow passage (12) at an external peripheral face, a valve rod (20) extending outward from a base end part (16a) of the valve body (16), and a valve chamber (18) for accommodating the valve body (16). The external peripheral face of the valve body (16) protruding to the flow passage (12) in an open position is formed of a streamlined curved face.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gate valve. [Background technology]

[0002] Conventionally, there have been proposed gate valves that open and close a flow path by raising and lowering a valve body in a direction perpendicular to the flow path. For example, a seal member is attached to the valve body of the gate valve in Patent Document 1 so as to protrude from the main body in order to ensure sealing. The seal member extends in a direction crossing the flow path and is configured to abut against the flow path in the circumferential direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-265029 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional gate valves, the flow of the fluid around the valve disc is not taken into consideration. Therefore, when the valve disc is stopped in the middle of its stroke, the seal member on the surface of the valve disc prevents the fluid from flowing smoothly, causing turbulence around the valve disc. As a result, when the valve disc is stopped in the middle of its stroke, the fluid becomes difficult to flow. Therefore, in conventional gate valves, in order to pass a larger flow rate, it is necessary to move the valve disc upwards significantly. In other words, in conventional gate valves, it is necessary to increase the range of the stroke movement of the valve disc.

[0005] An object of the present invention is to provide a gate valve that is capable of allowing a large flow rate even when stopped mid-stroke (when part of the valve body blocks the linear flow path). [Means for solving the problem]

[0006] One aspect of the present invention is a gate valve comprising: a valve box having a linear flow path and a valve chamber arranged to the side of the flow path; a valve element housed in the valve chamber and capable of closing the flow path by displacing in an axial direction perpendicular to the flow path so that its outer surface abuts the inner surface of the flow path; and a valve stem extending in the axial direction from a base end of the valve element, wherein the outer surface of the valve element that protrudes into the flow path in an open position is configured with a streamlined curved surface. Effect of the Invention

[0007] According to the gate valve of the above aspect, the generation of turbulence around the valve disc is reduced, and the fluid around the valve disc flows in a straight line, so that a larger flow rate of fluid can be passed even in the middle of a stroke (when part of the valve disc blocks the linear flow path). As a result, a larger flow rate can be passed with a smaller stroke, and it is possible to commercialize the gate valve with a smaller stroke compared to the conventional technology. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1A is a perspective cross-sectional view of a gate valve according to a first embodiment of the present invention, FIG. 1B is a perspective view of a valve body and a valve stem of the gate valve of FIG. 1A, and FIG. 1C is a cross-sectional view of the valve body of FIG. 1B. [Diagram 2] 1B is a perspective view of a flow passage and a valve chamber of the gate valve of FIG. 1A. [Diagram 3] FIG. 1B is a cross-sectional view of the gate valve of FIG. 1A in a valve closed state. [Figure 4] 4A is a cross-sectional view of the gate valve of FIG. 1A in an open state, and FIG. 4B is a schematic diagram showing the flow of fluid in a cross section taken along line IVB-IVB of FIG. 4A. [Diagram 5] FIG. 5A is a perspective cross-sectional view of a gate valve according to a second embodiment of the present invention, and FIG. 5B is a perspective view of the valve body and valve stem of FIG. 5A. [Figure 6] 5B is a perspective cross-sectional view of a flow passage and a valve chamber of the gate valve of FIG. 5A. [Figure 7] FIG. 11 is a cross-sectional view of a gate valve according to a third embodiment of the present invention. [Figure 8] FIG. 8A is a perspective cross-sectional view of a gate valve according to a fourth embodiment of the present invention, and FIG. 8B is a perspective view of the valve body of FIG. 8A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the dimensional ratios in the drawings may be exaggerated for the sake of explanation and may differ from the actual ratios. In the following description, the direction in which the valve body is pushed into the flow path is referred to as "downward" or "lower side", and the direction in which the valve body is retracted to the valve box side is referred to as "upward" or "upper side", but this does not limit the installation direction of the gate valve.

[0010] (First embodiment) 1A, the gate valve 10 according to this embodiment includes a valve box 14 in which a linear flow path 12 is formed, a valve element 16 that opens and closes the flow path 12 by rising and falling in an axial direction perpendicular to the flow path 12, a valve chamber 18 that houses the valve element 16, and a valve rod 20 that extends in the axial direction from a base end portion 16a of the valve element 16. The fluid that flows through the flow path 12 is a gas such as air or steam (including water vapor), a reduced pressure gas such as a vacuum pressure, a liquid such as water or oil, or a fluid such as a mixture of gel or solid particles and liquid, and the gate valve 10 can open and close the flow of these fluids.

[0011] The valve element 16 can be raised and lowered in the direction of an axis A perpendicular to the flow path 12, and when the valve element 16 is lowered to the bottom end, the outer surface of the valve element 16 comes into contact with the inner wall (inner surface) 12a of the flow path 12 to close the flow path 12. The valve element 16 includes a valve body 22 formed of metal, resin, or the like, and a seal member 24 that covers the outer surface of the valve body 22. The valve element 16 may also be configured with the valve body 22 made only of uncoated metal or resin. In this case, the valve body 22 of the valve element 16 can come into direct contact with the flow path 12 of the valve box 14 to close the flow path 12.

[0012] As shown in FIG. 1B, the valve body 22 is formed circularly symmetrically around the axis A. A tapered portion 22c is formed on the base end 22a side of the valve body 22, the diameter of which gradually decreases toward the tip 22b. A tip portion 22d having a spherical outer surface is formed on the tip 22b side of the valve body 22. If the radius of curvature of the spherical surface of the tip portion 22d is equal to or larger than the radius of curvature of the inner wall 12a of the flow path 12, it is preferable because it is easy to ensure adhesion between the tip 22b of the valve body 22 and the inner wall 12a. The valve body 22 is not limited to being circularly symmetrical around the axis A, and may have a streamlined shape with respect to the flow direction of the flow path 12. In this case, the shape of the valve body 22 may be, for example, an elliptical structure elongated in the flow path direction.

[0013] The boundary between tapered portion 22c and tip portion 22d is connected by a smooth, continuous curved surface. Furthermore, forming the outer surfaces of tapered portion 22c and tip portion 22d with streamlined curved surfaces is preferable because it reduces the disturbance of the flow of the fluid flowing near valve body 16. As shown in Fig. 1C, valve body 22 has a circular outer shape when viewed from tip 22b, and a cross section of valve body 16 cut in a direction perpendicular to axis A is also circular.

[0014] The seal member 24 covers the outer periphery of the valve body 22 and constitutes the outer surface of the valve disc 16. The seal member 24 can be made of an elastically deformable material such as rubber, various elastomers, nylon, polyethylene, or fluororesin such as polytetrafluoroethylene. The seal member 24 can be formed by coating the surface of the valve body 22 with the above material. The seal member 24 may also be attached by a method in which a cap-shaped member made of the above material is attached to the surface of the valve body 22.

[0015] The valve body 16 is not limited to a configuration in which the seal member 24 is provided on the surface of the valve body 22, and it is not necessary to form a separate seal member 24 on the surface. That is, the valve body 22 may be made of the above-mentioned elastically deformable material. The valve body 22 may also be made of only metal or resin.

[0016] A valve stem 20 extends from a base end 22a of the valve body 22. The valve stem 20 is formed in a cylindrical shape and extends linearly upward along the axial direction A of the valve disc 16. The valve stem 20 may be formed integrally with the valve body 22. The valve stem 20 extends to the outside of the valve box 14, and a drive mechanism (not shown) is attached to the end 20a. The drive mechanism drives the valve stem 20 and the valve disc 16 in the axial direction A. A packing 26 is attached to the outer periphery of the valve stem 20. As shown in FIG. 1A, the packing 26 abuts against a through hole 28 through which the valve stem 20 passes into the valve box 14, thereby sealing the valve chamber 18.

[0017] As shown in FIG. 2, the valve box 14 is formed with a flow path 12, a valve chamber 18, and a through hole 28. The flow path 12 is formed in a straight line and extends through the valve box 14 from one side 14c to the other side 14d. The cross-sectional shape of the flow path 12 is formed in a circular shape. The cross-sectional shape of the flow path 12 is not limited to a circular shape, and may be formed in a rectangular or polygonal shape. A seal groove 30 is provided near the center of the flow path 12. The seal groove 30 is provided in a portion that abuts against the valve body 16. The seal groove 30 extends in the circumferential direction of the flow path 12, and the upper end side is connected to the opening 18c of the valve chamber 18. The surface of the seal groove 30 may be formed with a curvature. In this case, if the curvature of the seal groove 30 is configured with a curved surface having the same curvature as the curvature of the outer surface of the valve body 16, the outer surface of the valve body 16 can be in surface contact with the surface of the seal groove 30 and closely adhere thereto, which is preferable because it improves the sealing performance.

[0018] The surface of the seal groove 30 does not have to be curved, and may be configured as a flat surface such as an inclined surface. As long as the outer surface of the valve body 16 has a shape that allows it to abut against the seal groove 30, it is not limited to a curved surface. Note that when the pressure of the fluid in the flow path 12 is low and high pressure is not applied to the valve body 16, the seal groove 30 does not have to be provided.

[0019] The valve chamber 18 is provided at the top of the flow path 12. The valve chamber 18 has an inclined portion 18b connected to the flow path 12, and a cylindrical portion 18a formed as a cylindrical cavity connected to the top of the inclined portion 18b. The cylindrical portion 18a is formed with an inner diameter slightly larger than the diameter of the base end portion 16a of the valve body 16, and is formed as a cylindrical cavity extending in the axial A direction. The inclined portion 18b is formed in a funnel shape with an inner diameter that decreases downward in the axial A direction.

[0020] The lower end of the inclined portion 18b opens into the flow path 12 as an opening 18c. The valve chamber 18 communicates with the flow path 12 via the opening 18c. The inclination angle (angle with respect to axis A) of the inner surface (tapered surface) of the inclined portion 18b is preferably approximately the same as the inclination angle (angle with respect to axis A) of the tapered portion 22c of the valve body 22. The inclined portion 18b is configured to come into surface contact with the tapered portion 22c of the valve body 22 when the valve element 16 is pressed down to the lower end, thereby closing the opening 18c of the valve chamber 18. The volume of the valve chamber 18 is approximately the same as the volume of the valve element 16.

[0021] A through hole 28 is formed above the center of the upper end of the valve chamber 18. The through hole 28 has approximately the same inner diameter as the valve stem 20, and penetrates toward the upper part of the valve box 14. The valve stem 20 is attached to the through hole 28.

[0022] The valve box 14 can be configured as two members, for example, a first portion 14a extending up to the upper end of the valve chamber 18, and a second portion 14b covering the upper end of the valve chamber 18. When attaching the valve body 16 to the gate valve 10, the first portion 14a and the second portion 14b can be separated to leave the upper end of the valve chamber 18 open. After inserting the valve body 16 into the valve chamber 18, the second portion 14b can be attached and fixed onto the first portion 14a, thereby allowing the valve body 16 to be inserted into the valve chamber 18.

[0023] Next, the operation of the gate valve 10 configured as above will be described.

[0024] As shown in Fig. 3, when the valve disc 16 is fully lowered, the seal member 24 of the valve disc 16 abuts against the inner wall 12a and the inclined portion 18b of the flow path 12, and the valve disc 16 blocks the flow path 12. At that time, the surface of the seal member 24 of the valve disc 16 enters the seal groove 30 and makes surface contact. Even if a force that tries to deform the seal member 24 is applied due to the pressure of the fluid on the upstream side of the flow path 12, the seal member 24 is held by the seal groove 30, so that the sealing performance is maintained. At this time, since the pressure on the upstream side remains in the valve chamber 18, a biasing force that presses the valve disc 16 downward is applied, and when the fluid flowing through the flow path 12 is at high pressure, the sealing performance is further improved.

[0025] The downward biasing force acting on the valve element 16 due to the pressure remaining in the valve chamber 18 can be adjusted as appropriate by adjusting the area of ​​the base end 16a of the valve element 16. In other words, when the diameter of the valve rod 20 is increased, the area of ​​the base end 16a of the valve element 16 is reduced, and the downward biasing force acting on the valve element 16 is reduced accordingly. In the valve closed state, a force acts on the valve element 16 due to the pressure from the upstream fluid of the flow path 12, which tends to push the valve element 16 upward. Therefore, by appropriately adjusting the area of ​​the base end 16a of the valve element 16, the upward force due to the pressure from the upstream fluid and the downward biasing force due to the pressure of the valve chamber 18 may be balanced (approximately the same magnitude). In that case, the valve element 16 can be pulled upward from the valve closed state with a light operating force.

[0026] 4A, when the valve disc 16 is raised and stopped midway through its stroke, the valve disc 16 separates from the inner wall 12a of the flow path 12, allowing the fluid to pass through the flow path 12. At this time, a gap is created between the inclined portion 18b and the valve disc 16, the valve chamber 18 and the flow path 12 communicate with each other, and the internal pressure of the valve chamber 18 and the flow path 12 become the same.

[0027] As shown in Fig. 4B, the valve body 16 is formed to be rotationally symmetric (circularly symmetric), and therefore has a circular cross section. Therefore, the flow of the fluid is kept straight without being disturbed around the valve body 16. Therefore, the fluid flows smoothly around the valve body 16, and a larger flow rate of the fluid can be made to flow through the flow path 12 simply by lifting the valve body 16 slightly.

[0028] The gate valve 10 provides the following advantages.

[0029] In the gate valve 10, the outer surface of the valve element 16 is formed as a streamlined curved surface in the flow path 12. This makes it difficult for the flow of fluid to be disturbed around the valve element 16, and even if the valve element 16 is stopped midway through its stroke, a larger flow rate of fluid can be allowed to flow through the flow path 12. This allows the flow path 12 to be opened and closed with a small stroke. Furthermore, the reduced stroke range allows the drive mechanism for the valve element 16 to be made more compact.

[0030] Furthermore, since the shape of the valve element 16 is symmetrical with respect to the flow direction of the flow passage 12, the orientation of the valve element 16 with respect to the valve box 14 may be any direction, making it easy to assemble the valve element 16 to the valve box 14. Moreover, the valve element 16 functions in the same way regardless of the flow direction of the flow passage 12.

[0031] In the gate valve 10, the tip 22b of the valve body 16 may be configured with a spherical surface. This makes it even more difficult for the flow of fluid to be disturbed around the valve body 16. In addition, since the contact portion with the flow path 12 is limited to a linear region (the portion of the seal groove 30) extending in the circumferential direction of the flow path 12, it is easier to increase the surface pressure at the contact portion. Therefore, even if the pressure of the fluid increases, high sealing performance can be obtained.

[0032] In the gate valve 10, a seal groove (recess) 30 recessed radially outwardly of the flow passage 12 may be formed on the inner surface of the flow passage 12 at a portion where the inner surface abuts against the outer surface of the valve body 16. The seal groove (recess) 30 may be formed in a groove shape in the circumferential direction of the flow passage 12. With this configuration, the surface of the seal member 24 of the valve body 16 is held in the seal groove 30, making it difficult for the seal member 24 to deform due to the pressure of the fluid, and improving the sealing performance.

[0033] The curvature of the seal groove (recess) 30 of the flow passage 12 may be substantially the same as the curvature of the outer surface of the valve body 16 at the portion that abuts against the seal groove (recess) 30. This brings the outer surface of the valve body 16 into close contact with the seal groove 30, improving the sealing performance.

[0034] The valve chamber 18 may be provided with an inclined portion 18b, so that when the valve element 16 is lowered into the flow path 12, the outer surface of the tapered portion 22c of the valve element 16 comes into contact with the inclined portion 18b of the valve chamber 18 to close the valve chamber 18. This makes it possible to block the flow of fluid through the valve chamber 18. Furthermore, when the valve element 16 is raised, the valve chamber 18 and the flow path 12 communicate with each other, and the internal pressures of the valve chamber 18 and the flow path 12 become the same. This prevents an increase in the lifting and lowering movement of the valve element 16 even if the pressure of the fluid increases, and allows the valve element 16 to be operated with less operating force.

[0035] As the stroke is reduced, the height of the cylindrical portion 18a of the valve chamber 18 can be reduced. This reduces the dead space in the valve box 14, and reduces the liquid pool. As a result, the gate valve 10 has excellent displacement characteristics and can allow the fluid to flow without leaving excess fluid in the valve box 14.

[0036] Second embodiment As shown in Fig. 5A, the gate valve 40 of this embodiment differs from the gate valve 10 of Fig. 1A in the shape of the valve body 16A and the recess 50 formed in the flow path 12. Note that in the gate valve 40, the same components as those in the gate valve 10 of Fig. 1A are denoted by the same reference numerals and detailed description thereof will be omitted.

[0037] As shown in Fig. 5B, the valve body 16A includes a valve body 44 having a flat surface 44a formed at the tip. The valve body 44 is tapered so that the diameter gradually decreases from the base end 44b toward the flat surface 44a at the tip. As shown in Fig. 5A, the surface of the valve body 44 is covered with a seal member 46.

[0038] As shown in FIG. 6, the valve box 14A includes a second portion 42 having a flow passage 12. In the second portion 42, a recess 50 is formed at the center lower end of the inner wall 12a of the flow passage 12 to accommodate the flat surface 44a at the tip of the valve body 44. The recess 50 has an inner diameter substantially equal to the diameter of the flat surface 44a of the valve body 44. A valve chamber 48 is formed at the center upper portion of the flow passage 12. The valve chamber 48 includes an inclined portion 48b communicating with the flow passage 12 via an opening 48c, and a cylindrical portion 48a formed on the inclined portion 48b. The inclined portion 48b extends in the circumferential direction of the flow passage 12 along the inner wall 12a of the flow passage 12, and communicates with the recess 50.

[0039] The inner diameter of the cylindrical portion 48a is formed slightly larger than the diameter of the base end portion 44b of the valve body 16A. The angle of the tapered surface of the inclined portion 48b (angle with respect to the axis A) is the same as the inclination angle of the side wall of the valve body 44 of the valve body 16A (angle with respect to the axis A), and when the valve body 16A is pressed down, the valve body 16A is in surface contact with the inclined portion 48b to close the valve chamber 48 with the valve body 16A. At this time, the valve body 16A is in surface contact with the inclined portion 48b and the recess 50 extending in the circumferential direction of the flow path 12 to completely close the flow path 12. That is, the recess 50 is formed to have the same diameter as the flat surface 44a of the valve body 44, and is configured to close the flow path 12 airtightly and liquidtightly by the flat surface 44a coming into contact with the recess 50.

[0040] The valve body 44 and the recess 50 of this embodiment are not limited to the above configuration, and may be tapered so that the side of the recess 50 gradually decreases in diameter in the direction from the flow path 12 side, and the bottom surface of the recess 50 at the back may be formed to be smaller in diameter than the flat surface 44a. In this case, the flat surface 44a of the valve body 44 abuts against the tapered side of the recess 50 to close the flow path 12 in an airtight and liquidtight manner. At this time, the valve body 44 does not need to abut against the bottom surface of the recess 50. In such a configuration, sufficient airtightness and liquidtightness can be obtained, which is preferable, even if the machining accuracy of the recess 50 and the valve body 44 is relatively low.

[0041] The gate valve 40 configured as above provides the following advantages.

[0042] The valve body 16A of the gate valve 40 is formed in a tapered shape with a diameter decreasing toward the tip, and the tip portion is composed of a flat surface 44a parallel to the flow path 12. This makes it difficult for the flow of fluid to be disturbed around the valve body 16A, and even if the valve body 16A is stopped midway through the stroke, a larger flow rate of fluid can be allowed to flow through the flow path 12. Therefore, the flow path 12 can be opened and closed with a small stroke.

[0043] In the gate valve 40, too, a recess 50 recessed radially outwardly of the flow passage 12 is formed on the inner surface of the flow passage 12 at a portion where the inner surface abuts against the outer surface of the valve body 16A. This ensures high sealing performance even when the fluid pressure increases.

[0044] (Third embodiment) As shown in Fig. 7, a gate valve 60 of this embodiment differs from the gate valve 10 of Fig. 1A in that a seal portion 61 is provided on the flow path 12 side. Note that in the gate valve 60, the same components as those in the gate valve 10 of Fig. 1A are denoted by the same reference numerals and detailed description thereof will be omitted.

[0045] In the gate valve 60, a mounting portion 12b is formed by cutting out a part of the inner periphery in the flow path 12 of the second portion 42B of the valve box 14B. A seal portion 61 is attached to the mounting portion 12b. The seal portion 61 is a member formed in a substantially cylindrical shape, and is made of an elastically deformable material such as rubber, various elastomers, nylon, polyethylene, or fluororesin such as polytetrafluoroethylene.

[0046] The seal portion 61 has a cylindrical main body 62, a flow passage 64 formed inside the main body 62, a recess 66 that contacts the tip of the valve body 16, and an opening 68 that communicates with the valve chamber 18. The main body 62 is formed so that its radial thickness and axial length are the same as the radial depth and axial length of the cutout portion that constitutes the mounting portion 12b. Inside the main body 62, a flow passage 64 is formed that penetrates in the same direction as the axis of the flow passage 12. The inner circumferential surface of the flow passage 64 is formed flush with the inner circumferential surface of the flow passage 12. The recess 66 is formed on the inner circumferential surface of the flow passage 64 at the portion that contacts the valve body 16. The recess 66 has the same shape as the seal groove 30 in FIG. 2 and extends in the circumferential direction of the flow passage 64. The inner surface of the recess 66 is configured to have approximately the same curvature as the tip of the valve body 16. The valve body 16 may not include the seal member 24 and may be composed of only the valve body 22.

[0047] The opening 68 is formed in the upper part of the main body 62, penetrating the main body 62 in the axial direction of the valve disc 16. The inner circumferential surface of the opening 68 is inclined at the same inclination as the surface of the inclined portion 18b of the valve chamber 18, and is composed of the same curved surface. The inner circumferential surface of the opening 68 is configured to come into airtight or liquidtight surface contact with the tapered portion 22c near the base end 16a of the valve disc 16, so as to be able to seal the valve chamber 18 when the valve disc 16 is pressed down to the valve closed position.

[0048] According to the gate valve 60 configured as described above, the seal portion 61 can be in airtight or liquid-tight contact with the valve body 16, so that sealing performance can be ensured even without forming the seal member 24 on the surface of the valve body 16.

[0049] (Fourth embodiment) As shown in Fig. 8A, the gate valve 70 of this embodiment differs from the gate valve 40 of Fig. 5A and Fig. 5B in the configuration of the valve body 16B and in the presence of a communication passage 72. Note that in the gate valve 70, the same components as those in the gate valve 40 of Fig. 5A and Fig. 5B are denoted by the same reference numerals and detailed description thereof will be omitted.

[0050] As shown in Fig. 8B, the valve body 16B includes a valve body 44 having a flat surface 44a formed at the tip. The valve body 44 is tapered such that the diameter gradually decreases from the base end 44b toward the flat surface 44a at the tip. In this embodiment, only the side surface 44c of the valve body 44 is covered with the seal member 46. The base end 44b and the flat surface 44a of the valve body 44 are not covered with the seal member 46, and the flat surface 44a is configured to directly abut against the recess 50.

[0051] 8A, the valve box 14B has a communication passage 72 that communicates between the flow path 12 and the valve chamber 48. One end of the communication passage 72 communicates with the upstream side of the flow path 12, and the other end communicates with the valve chamber 48. The other configurations of the second portion 42 of the valve box 14B are similar to those of the second portion 42 shown in FIG.

[0052] The gate valve 70 configured as above provides the following advantages.

[0053] In the gate valve 70 of this embodiment, the valve box 14B is provided with a communication passage 72 that communicates the flow path 12 and the valve chamber 48. When the valve element 16B is fully pressed to close the flow path 12 by the valve element 16B, the communication passage 72 transmits the pressure on the upstream side of the flow path 12 to the valve chamber 48. As a result, the valve element 16B is urged in a direction to close the flow path 12 by the pressure difference between the valve chamber 48 and the downstream side of the flow path 12, improving the sealing performance of the valve element 16B and enabling the flow path 12 to be closed more reliably.

[0054] In the valve body 16B of this embodiment, in order to close the flow path 12, the valve chamber 48 of Since the side surface 44c that comes into surface contact with the inclined portion 48b is covered with the seal member 46, sufficient sealing performance can be ensured.

[0055] The communicating passage 72 is not limited to this embodiment, and may be provided in the gate valves 10, 40, and 60 described with reference to Figures 1A to 7, in which case the same effects as those of the gate valve 70 can be obtained.

[0056] The embodiments of the present invention are not limited to the above-mentioned embodiments, and various modifications are possible. For example, as shown in Fig. 5B, a valve body 44 that is not covered with an elastic seal member 46 may be used as the valve element 16B. In this case, the metal surface of the valve body 44 directly contacts the inclined portion 48b and the recessed portion 50 (see Fig. 6) of the valve chamber 48, thereby closing the flow path 12 in an air-tight and liquid-tight manner.

[0057] 1B may be used as the valve element 16. In this case, the metal surface of the valve body 22 is directly Channel 12 The seal groove 30 of the valve body 44 comes into contact with the seal groove 30 of the valve body 44 to close the flow path 12 airtight and liquidtight. As a result, the surface of the valve body 44 is less likely to deform due to friction and pressure, compared to when the valve body 44 is covered with a seal member 46 made of a rubber material, a resin material, or the like. Therefore, when a valve body 44 that is not covered with a seal member 46 is used, a gate valve with excellent abrasion resistance and pressure resistance is obtained. [Explanation of symbols]

[0058] 10, 40, 60, 70...Gate valve 12, 64...Flow path 14, 14A, 14B... Valve body 16, 16A, 16B... Valve body 18, 48... Valve chamber 20... Valve stem 50, 66 ... recess 61 ... seal portion 72…Communication path

Claims

[Claim 1] a valve body (14) having a linear flow passage (12) and a valve chamber (18) disposed on a side of the flow passage (12); a valve body (16) that is accommodated in the valve chamber (18) and is displaceable in an axial direction perpendicular to the flow path (12) so that an outer surface of the valve body comes into contact with an inner surface of the flow path (12) to close the flow path (12); a valve stem (20) extending in the axial direction from a base end (16a) of the valve body (16), the flow passage (12) has an inner diameter at an end of the valve box (14) and an inner diameter at a portion adjacent to an opening (18c) of the valve chamber (18) that are the same, and has a seal groove (30) that extends in the circumferential direction of the flow passage (12) and communicates with the valve chamber (18) at a portion that abuts against the valve body (16); The valve body (16) includes a valve body (22) having a tapered portion (22c) formed in a tapered shape with a diameter decreasing toward the tip side, and a tip portion (22d) formed at the tip of the tapered portion (22c), and a seal member (24) covering an outer surface of the valve body (22), and is formed rotationally symmetrical about an axis extending from the valve rod (20), The tip portion (22d) has an outer surface formed of a spherical surface having a radius larger than the radius of curvature of the inner wall (12a) of the flow path (12), The gate valve (10), wherein the seal groove (30) is formed with a curved surface having the same curvature as the curvature of the outer surface of the valve body (16).

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