Butterfly valve

Abstract

The purpose of the present invention is to provide a butterfly valve with which it is possible to achieve stable, high compressive surface pressure.　The butterfly valve comprises: a valve rod unit 40 capable of rotating around a valve rod body 41; a valve body unit 50 that turns as a result of the rotation of the valve rod unit 40 and that opens and closes a flow passage F; and a valve seat 30 that is provided between the valve casing 10 and the valve body unit 50, and seals the space therebetween. The butterfly valve further comprises: a rotation-restricting mechanism MR that permits a first rotation of the valve body unit 50, restricts rotation of the valve body unit 50 accompanying a second rotation of the valve stem unit 40, and permits movement of the direct-front-side DF valve body unit 50 that is attached to the valve seat 30; and a rotation-to-movement conversion mechanism MD that moves the valve body unit 50 so as to be attached to the valve seat 30 through the second rotation of the valve stem unit 40 relative to the valve body unit 50, the rotation of which is restricted by the rotation-restricting mechanism MR.

Description

Butterfly Valve

[0001] The present invention relates to, for example, a butterfly valve connected to a pipe, which adjusts the flow rate of fluid in the pipe by opening and closing the flow, or switches between opening and shutting off the flow.

[0002] Conventionally, as shown in Patent Document 1, a butterfly valve is used, which includes a valve box having a tubular flow path, a valve stem rotatably provided in the valve box, a valve body rotated by the valve stem to open and close the flow path, and a valve seat (seat ring) provided between the valve box and the valve body, and adjusts the flow rate of fluid by opening and closing the flow, or switches between opening and shutting off the flow.

[0003] However, in the butterfly valve as disclosed in Patent Document 1, the valve body is brought into contact with the valve seat in the valve closed state to shut off the flow. Therefore, when shutting off the flow of a fluid with a small molecular size such as hydrogen or helium, or a fluid at an extremely low temperature such as cryogenic temperature, it is necessary to increase the compressive contact surface pressure between the valve seat and the valve body, and it has been difficult to stably maintain a high compressive contact surface pressure.

[0004] Japanese Patent Application Laid-Open No. 2003-185047

[0005] An object of the present invention is to provide a butterfly valve capable of obtaining stable and high compressive contact surface pressure.

[0006] This invention comprises a valve body having a tubular flow path, a valve stem rotatable about an axis relative to the valve body, a valve element that rotates with the rotation of the valve stem to open and close the flow path, and a valve seat provided between the valve body and the valve element for sealing. The rotation from the open position to a predetermined angle is considered the first rotation, and the rotation of the valve stem from the predetermined angle to the closed position is considered the second rotation. The first rotation of the valve element is permitted, while the rotation of the valve element accompanying the second rotation of the valve stem is restricted, and the forward rotation in the direction of close contact with the valve seat is also restricted. The butterfly valve is characterized by being provided with a rotation restricting mechanism that allows movement of the valve body, and a rotational movement conversion mechanism that moves the valve body so that it is in close contact with the valve seat by the second rotation of the valve stem relative to the valve body whose rotation is restricted by the rotation restricting mechanism, wherein the rotational movement conversion mechanism is provided on at least one of the valve stem and the valve body and has a cam portion that, by the second rotation of the valve stem, comes into contact with the other of the valve stem and the valve body, and moves the valve body so that it is in close contact with the valve seat.

[0007] The butterfly valve described above may be a center-type butterfly valve, or it may be configured as a single-sided eccentric butterfly valve or a double-sided eccentric butterfly valve. The valve body described above may also be called the valve body, housing, or simply the valve casing.

[0008] The valve seat described above is sometimes called a seat ring. The rotational movement conversion mechanism described above can move the valve body so that it is in close contact with the valve seat, and the direction of its movement may be along the direction of fluid flow, in a direction intersecting the direction of flow, or in the opposite direction to the direction of flow.

[0009] The cam portion described above becomes convex in that, upon the first rotation of the valve stem, the portion that contacts the other side of the valve stem and valve body becomes longer in diameter than the portion that contacts the other side of the valve stem and valve body upon the second rotation.

[0010] This invention makes it possible to obtain a stable and high compression pressure. More specifically, the butterfly valve is equipped with a rotation restricting mechanism that allows the valve body to rotate once, restricts the rotation of the valve body accompanying the second rotation of the valve stem, and allows the valve body to move in the direction of tight contact with the valve seat. Therefore, the rotation restricting mechanism allows the valve body to rotate once from the open position to a predetermined angle in conjunction with the first rotation of the valve stem from the open position to a predetermined angle.

[0011] Furthermore, the butterfly valve is provided with a rotational movement conversion mechanism that moves the valve body to make close contact with the valve seat by a second rotation of the valve stem relative to the valve body whose rotation is restricted by a rotational restriction mechanism. The rotational movement conversion mechanism also has a cam portion that, by the second rotation of the valve stem, comes into contact with the other of the valve stem and the valve body, moving the valve body to make close contact with the valve seat.

[0012] Therefore, even if the valve stem rotates a second time, the rotation of the valve body that has rotated a first time is restricted by the rotation restriction mechanism. However, a rotational movement conversion mechanism is provided on at least one of the valve stem and the valve body, and has a cam portion that, in response to the second rotation of the valve stem, comes into contact with the other valve stem and the valve body, moving the valve body to make close contact with the valve seat. This mechanism allows the cam portion to come into contact with the other valve stem and the valve body as the valve stem rotates a second time, moving the valve body to make close contact with the valve seat.

[0013] Therefore, in the closed state, the valve body and valve seat are in close contact under high compressive pressure. Consequently, even when blocking the flow of fluids with small molecular sizes or extremely low temperatures such as cryogenic fluids, the fluid flow can be reliably blocked without any leakage between the valve body and valve seat.

[0014] In one embodiment of this invention, the valve stem may be provided with a transmission member having a rotation transmission portion that transmits the first rotation of the valve stem to the valve body, and a support shaft may be provided along the axis that rotatably supports the transmission member on the side opposite to the valve stem relative to the valve body.

[0015] This invention enables stable rotation of the valve body, which rotates with the first rotation of the valve stem, by providing a support shaft along the axis and on the opposite side of the valve stem from the valve body. Furthermore, the rotational force of the valve stem during the first rotation is reliably transmitted to the valve body by the transmission member, thus ensuring that the valve body rotates reliably with the first rotation of the valve stem.

[0016] In another aspect of this invention, the rotation transmission unit, the rotation restricting mechanism, and the rotational movement conversion mechanism may be provided on both sides of the valve body in the axial direction along the axis. With this invention, compared to the case where the rotation transmission unit, rotation restricting mechanism, and rotational movement conversion mechanism are provided on both sides in the axial direction, the rotation transmission unit, rotation restricting mechanism, and rotational movement conversion mechanism can be provided on one side of the axial direction to stably restrict the rotation of the valve body accompanying the second rotation of the valve stem, while the rotational movement conversion mechanism moves the valve body in a direction that brings it into close contact with the valve seat, thereby reliably blocking the flow path when the valve is closed.

[0017] Furthermore, since a support shaft is provided along the axis that rotatably supports the transmission member on the side opposite to the valve stem relative to the valve body, the rotational movement conversion mechanism, which is located on the side opposite to the valve stem relative to the valve body, can be reliably operated in the closed valve state, thereby more reliably blocking the flow path.

[0018] In another aspect of this invention, the cam portion is provided on the transmission member, and the transmission member is provided with a planar maintaining contact surface that contacts the valve body to maintain the valve body in close contact with the valve seat, and the rotation transmission portion has a planar transmission contact surface that contacts the valve body, and the transmission contact surface, the cam portion, and the maintaining contact surface may be provided in this order from the front of rotation to the rear of rotation in the forward rotation direction from the first rotation to the second rotation.

[0019] This invention allows the first rotation of the valve stem to be reliably transmitted to the valve body by the transmission contact surface that contacts the valve body, and the valve body to maintain a tight seal with the valve seat by the maintenance contact surface.

[0020] Furthermore, since the transmission contact surface, cam portion, and maintenance contact surface are arranged in this order from the front to the rear of rotation in the forward rotation direction, the valve body rotated by the first rotation of the valve stem can be pressed against the valve seat by the cam portion during the second rotation of the valve stem, and the maintenance contact surface can maintain the valve body in close contact with the valve seat. In this way, by simply rotating the valve stem in the forward rotation direction from the open valve position, the valve body can be reliably rotated, and the state in which the valve body is in close contact with the valve seat can be reliably maintained.

[0021] In another aspect of this invention, a portion of the transmission member may be provided with an offset portion that is offset in a predetermined direction from the axis to suppress the reduction of the flow area in the open valve state. With this invention, the flow path can be reliably blocked in the closed valve state by moving the valve body in a direction that makes close contact with the valve seat using a rotational movement conversion mechanism, without reducing the flowability in the open valve state.

[0022] Furthermore, in an embodiment of this invention, the rotation of the valve stem from the closed position to the predetermined angle is set to a second reverse rotation, and the rotation from the predetermined angle to the open position is set to a first reverse rotation. The rotational movement conversion mechanism is provided to move the valve body, which has been moved to be in close contact with the valve seat by the rotational movement conversion mechanism, away from the valve seat by the second reverse rotation of the valve stem, and to rotate the valve body to the first reverse rotation by the first reverse rotation of the valve stem. The rotational movement conversion mechanism may have a second cam portion provided on at least one of the valve stem and the valve body, which, when the second reverse rotation of the valve stem is performed on the valve body that is in close contact with the valve seat, comes into contact with the other of the valve stem and the valve body, thereby moving the valve body away from the valve seat.

[0023] This invention makes it possible to easily open a butterfly valve that is in a closed state. More specifically, the butterfly valve is provided with a rotational movement conversion mechanism that moves the valve body, which has been moved to be in close contact with the valve seat by the rotational movement conversion mechanism, away from the valve seat by the second reverse rotation of the valve stem, and rotates the valve body in the first reverse rotation by the first reverse rotation of the valve stem. Therefore, the rotational movement conversion mechanism allows the valve body to be moved away from the valve seat by the second reverse rotation of the valve stem, and the valve body to be rotated in the first reverse rotation in conjunction with the first reverse rotation of the valve stem.

[0024] Furthermore, the rotational reverse movement conversion mechanism is provided on at least one side and has a second cam portion that, by the second reverse rotation of the valve stem relative to the valve body which is in close contact with the valve seat, comes into contact with the other side of the valve stem and the valve body, thereby moving the valve body away from the valve seat.

[0025] Therefore, a second reverse rotation of the valve stem relative to the valve body that is in close contact with the valve seat causes the second cam portion to come into contact with the other side of the valve stem and valve body, moving the valve body away from the valve seat. This second reverse rotation of the valve stem separates the valve body from the valve seat, and a first reverse rotation of the valve stem allows the butterfly valve to be easily opened.

[0026] In another aspect of this invention, the rotational reverse movement conversion mechanism may be provided on both sides of the valve body in the axial direction along the axis. With this invention, the rotational reverse movement conversion mechanism provided on both sides in the axial direction can reliably separate the valve body from the valve seat in response to the second reverse rotation of the valve stem, and reliably open the butterfly valve in response to the first reverse rotation of the valve stem.

[0027] In another aspect of this invention, the transmission member is provided with a reverse rotation transmission section that transmits the reverse second rotation of the valve stem to the valve body, and a planar valve-opening maintenance contact surface that contacts the valve body to maintain the separation state of the valve body from the valve seat, and the second cam section is provided on the transmission member, and the reverse rotation transmission section has a planar second transmission contact surface that contacts the valve body, and the second transmission contact surface, the second cam section and the valve-opening maintenance contact surface may be provided in this order from the front of the reverse rotation to the rear of the reverse rotation in the reverse rotation direction from the reverse second rotation to the reverse first rotation.

[0028] This invention enables the rotational force of the valve stem during the second reverse rotation to be reliably transmitted to the valve body by the second transmission contact surface of the transmission member, and also enables the valve body to be kept separated from the valve seat by the valve opening maintenance contact surface.

[0029] Furthermore, since the second transmission contact surface, the second cam portion, and the valve opening maintenance contact surface are arranged in this order from the front of the reverse rotation to the rear of the reverse rotation, simply by rotating the valve stem in the reverse rotation direction from the closed valve state, the valve body can be reliably separated from the valve seat and the valve body can be reliably rotated to reliably maintain the open valve state.

[0030] In another aspect of this invention, the rotational reverse movement conversion mechanism may be provided on the opposite side of the axis from the rotational movement conversion mechanism. With this invention, at least one of the rotational movement conversion mechanism and the rotational reverse movement conversion mechanism is in contact with the valve body, so that the movement of the valve body toward or away from the valve seat due to the rotation of the valve stem can be reliably controlled.

[0031] The present invention provides a butterfly valve that can obtain a stable and high compression pressure.

[0032] Diagram of the butterfly valve. Diagram of the butterfly valve. Diagram of the butterfly valve. Diagram of the butterfly valve. Diagram of the butterfly valve. Diagram of the opening and closing mechanism. Diagram of the transmission member. Diagram of the transmission member. Diagram of the valve body unit. Diagram of the valve body unit. Diagram of the fixed base. Exploded perspective view of the main mechanism. Exploded perspective view of the main mechanism. Diagram of the opening and closing operation of the butterfly valve. Schematic exploded perspective view of the transmission member and valve body unit of the second embodiment.

[0033] (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. Figures 1 to 5 show explanatory diagrams of the butterfly valve 1 of the first embodiment, Figure 6 shows an explanatory diagram of the opening and closing mechanism Y, Figures 7 and 8 show explanatory diagrams of the transmission member 42 in the open state, Figures 9 and 10 show explanatory diagrams of the valve body unit 50 in the open state, Figure 11 shows an explanatory diagram of the fixed base 60, Figures 12 and 13 show exploded perspective views of the main body mechanism X, and Figure 14 shows an explanatory diagram of the opening and closing operation of the butterfly valve 1.

[0034] More specifically, Figure 1(a) shows schematic perspective views of the front, right side, and top of the butterfly valve 1, and Figure 1(b) shows schematic perspective views of the rear, left side, and bottom of the butterfly valve 1. In Figure 1, the flange FL is shown with a dashed line.

[0035] Figure 2(a) shows a front view of the butterfly valve 1 in the open state, Figure 2(b) shows a rear view of the butterfly valve 1 in the same state, Figure 2(c) shows a front view of the butterfly valve 1 in the first rotation state, and Figure 2(d) shows a rear view of the butterfly valve 1 in the same state.

[0036] Figure 3(a) shows a view along the line A-A in Figure 1(a) with the valve stem unit 40 having made one rotation, and Figure 3(b) shows a view along the line B-B in Figure 3(a). Figure 4(a) shows a schematic perspective view of the front, right side, and top of the butterfly valve 1 in the open state, with the main body mechanism X visible through it. Figure 4(b) shows a schematic perspective view of the butterfly valve 1 in the open state, with the main body mechanism X visible through it. Figure 4(c) shows a schematic perspective view of the front, right side, and top of the butterfly valve 1 in the open state, with the opening / closing mechanism Y visible through it.

[0037] Figure 5(a) shows a schematic perspective view of the back, left side, and bottom of the butterfly valve 1 in the open state, with the main body mechanism X visible through it. Figure 5(b) shows a schematic perspective view of the back, left side, and bottom of the butterfly valve 1 in the state where the valve stem unit 40 has been rotated for the first time, with the main body mechanism X visible through it. Figure 5(c) shows a schematic perspective view of the back, left side, and bottom of the butterfly valve 1 in the state where the valve stem unit 40 has been rotated for the first time, with the opening and closing mechanism Y visible through it.

[0038] Figure 6(a) shows a schematic exploded perspective view of the back, right side, and top of the opening / closing mechanism Y in the state where the valve stem unit 40 has been rotated for the first time, and Figure 6(b) shows a schematic exploded perspective view of the front, right side, and bottom of the opening / closing mechanism Y in the same state.

[0039] Figure 7(a) is a perspective view showing the front, top, and right side of the transmission member 42, Figure 7(b) is a perspective view showing the rear, top, and right side of the transmission member 42, and Figure 7(c) is a front view of the transmission member 42. Figure 8(a) is an enlarged plan view of the upper transmission horizontal section 421U of the upper HU of the transmission member 42 that constitutes the rotational movement conversion mechanism MD, and Figure 8(b) is an enlarged view taken along the line E-E in Figure 7(c). Note that Figures 7 and 8 show the transmission member 42 in the open valve state. Also, the dashed line S in Figure 8(a) represents a roughly square with sides along the width direction W and the depth direction D in the state shown in Figure 8(a).

[0040] Figure 9(a) is a perspective view showing the front, top, and left side of the valve body unit 50, Figure 9(b) is a perspective view showing the rear, bottom, and left side of the valve body unit 50, and Figure 9(c) is a front view of the valve body unit 50. Figure 10(a) is an enlarged plan view of the valve body unit 50, and Figure 10(b) is an enlarged view taken along the line F-F in Figure 9(c). Note that Figure 9 shows the valve body unit 50 in the open position.

[0041] FIG. 11(a) is a bottom view of the fixing base 60 of the upper HU, and FIG. 11(b) is a perspective cross-sectional view of the fixing base 60 of the upper HU. FIG. 12 is a schematic exploded perspective view showing the front, right side and top of the main body mechanism X, and FIG. 13 is a schematic exploded perspective view showing the back, left side and bottom of the main body mechanism X.

[0042] FIG. 14 is a diagram for explaining the opening and closing operation of the butterfly valve 1; FIG. 14(a) is a cross-sectional view taken along line C-C of FIG. 3(a) in the valve open state; FIG. 14(b) is a cross-sectional view taken along line D-D of FIG. 3(a) in the same state; and FIG. 14(c) is a cross-sectional view taken along line E-E of FIG. 3(a) in the same state. Further, FIG. 14(d) is a cross-sectional view taken along line C-C of FIG. 3(a) showing the 90-degree rotation position where the valve stem unit 40 is rotated 90 degrees clockwise from the valve open state, that is, after the first rotation; FIG. 14(e) is a cross-sectional view taken along line D-D of FIG. 3(a) in the same state; and FIG. 14(f) is a cross-sectional view taken along line E-E of FIG. 3(a) in the same state.

[0043] Furthermore, FIG. 14(g) is a cross-sectional view taken along line C-C of FIG. 3(a) showing the 115-degree rotation position where the valve stem unit 40 is rotated 115 degrees clockwise from the valve open state; FIG. 14(h) is a cross-sectional view taken along line D-D of FIG. 3(a) in the same state; and FIG. 14(i) is a cross-sectional view taken along line E-E of FIG. 3(a) in the same state.

[0044] Still furthermore, FIG. 14(j) is a cross-sectional view taken along line C-C of FIG. 3(a) showing the valve closed state where the valve stem unit 40 is rotated 135 degrees clockwise from the valve open state; FIG. 14(k) is a cross-sectional view taken along line D-D of FIG. 3(a) in the same state; and FIG. 14(l) is a cross-sectional view taken along line E-E of FIG. 3(a) in the same state.

[0045] It should be noted that in the above drawings, illustrations of bolt holes for inserting and fastening bolts, the bolts themselves and the like are omitted. Further, in FIG. 1(a), the vertical direction is defined as the height direction H, the direction connecting the upper left and the lower right is defined as the width direction W, and the direction connecting the upper right and the lower left is defined as the depth direction D.

[0046] Furthermore, in FIG. 1(a), the upper side in the height direction H is defined as the upper side HU, and the lower side is defined as the lower side HD. In addition, in FIG. 1(a), the upper-left side in the width direction W, which is the direction connecting the upper left and lower right, is defined as the left side WL, the lower-right side is defined as the right side WR, the upper-right side in the depth direction D, which is the direction connecting the upper right and lower left, is defined as the back side DB, and the lower-right side is defined as the front side DF. Note that regardless of the width direction W or the depth direction D, the direction orthogonal to the height direction H is referred to as the horizontal direction.

[0047] Furthermore, for the butterfly valve 1 described in the present embodiment, among the rotation directions of the valve stem unit 40, clockwise rotation in plan view is rotation in the valve closing direction, and counterclockwise rotation in plan view is rotation in the valve opening direction. Furthermore, the rotation of the valve stem unit 40 from the valve opening position where the butterfly valve 1 opens to the 90-degree rotation position rotated 90 degrees clockwise is referred to as a first rotation, and the rotation of the valve stem unit 40 from the 90-degree rotation position to the valve closing position where the butterfly valve 1 closes is referred to as a second rotation.

[0048] Furthermore, the rotation of the valve stem unit 40 from the valve closing position where the butterfly valve 1 closes to the 90-degree rotation position counterclockwise is referred to as a reverse second rotation, and the rotation of the valve stem unit 40 from the 90-degree rotation position to the valve opening position where the butterfly valve 1 opens is referred to as a reverse first rotation.

[0049] The butterfly valve 1 is a valve device to which unillustrated piping is connected, for allowing or blocking the flow of fluid such as gas or liquid flowing through the piping, and further adjusting the flow rate, and is also called a so-called single-eccentric butterfly valve. Note that, for the butterfly valve 1, as illustrated by broken lines in FIG. 1, a flange FL to which piping is connected is provided on the valve body 10, but illustration of the flange FL is omitted in figures other than FIG. 1.

[0050] The butterfly valve 1 includes: a main body mechanism X having at least a valve body 10 internally including a flow path F along the depth direction D and a valve seat 30; and an opening-closing mechanism Y having at least a valve stem unit 40 rotatably provided on the valve body 10, and a valve body unit 50 rotated by the valve stem unit 40 to open and close the flow path F.

[0051] First, the main body mechanism X will be described with reference to Figures 12 and 13. As shown in Figures 12 and 13, the main body mechanism X comprises a valve body 10 and a valve seat 30. The valve body 10 is formed in a rectangular box shape with a flow path F that runs along and penetrates the depth direction D. The flow path F is formed in a circular shape when viewed from the front relative to the rectangular box-shaped valve body 10.

[0052] The upper and lower portions of the valve body 10 have through-holes 11 in the center of the plan view, which extend through in the height direction H and communicate with the flow path F. Furthermore, as shown in Figure 12, the front portion of the valve body 10 is provided with a mounting portion 12 for attaching the valve seat 30.

[0053] The mounting portion 12 protrudes inward from the inner surface of the valve body 10 at a position where it enters the rear side DB from the end of the front side DF of the valve body 10. The inward diameter of the mounting portion 12 that protrudes inward from the inner surface of the valve body 10 is the flow opening 13. The valve body 10 configured in this way is made of metal.

[0054] The valve seat 30 is attached to the mounting portion 12 and is a sealing member that contacts the valve body 51 of the opening / closing mechanism Y (described later) to seal the flow opening 13. When viewed from the depth direction D, it is formed in a ring shape that narrows in diameter one step towards the inner side DB. The valve seat 30 is formed with an appropriate cross-sectional shape for contacting and sealing the valve body 51 and is made of an elastic material with appropriate elasticity. The valve seat 30 is also called a seat ring. The main body mechanism X can be formed by attaching the valve seat 30 configured as described above to the mounting portion 12.

[0055] As shown in Figure 6, the opening and closing mechanism Y, which is attached to the main body mechanism X described above and constitutes the butterfly valve 1, includes a valve stem unit 40 that is rotatably mounted on the valve body 10, a valve body unit 50 that is rotated by the valve stem unit 40 to open and close the flow path F, and a fixed base 60 that is fixed to the valve body 10 and supports the valve stem unit 40, which is arranged vertically symmetrically along the height direction H.

[0056] As shown in Figure 6, the valve stem unit 40 consists of a valve stem body 41 formed in a substantially cylindrical shape having a predetermined length in the height direction H, a transmission member 42 attached to the lower HD of the valve stem body 41 and transmitting the rotation of the valve stem body 41 to the valve body unit 50, and a pivot shaft 43 that rotatably supports the lower HD of the transmission member 42.

[0057] The valve stem body 41 is formed in a substantially cylindrical shape, with a rectangular fitting portion 411 at its lower end, an enlarged diameter portion 412 positioned above it, and an operating portion 413 at its upper end. The rectangular fitting portion 411 provided at the lower end of the valve stem body 41 is a portion that fits into the fitting hole 44 of the transmission member 42, which will be described later, and is formed at a predetermined height and in a square shape when viewed from the bottom. The rectangular fitting portion 411 has a height H that is slightly longer than the thickness of the vertical portion 53 of the valve body of the valve body support portion 52, which will be described later.

[0058] The enlarged diameter portion 412, located above the rectangular fitting portion 411 of the valve stem body 41, is positioned at a position HU slightly above the sum of the plate thicknesses of the transmission horizontal portion 421 and the valve body horizontal portion 54 of the transmission member 42 (described later), and is enlarged in an annular shape. Two such portions are provided in the vertical direction.

[0059] Furthermore, the operating portion 413 provided at the upper end of the valve stem body 41, when assembled to the valve casing 10, protrudes from the upper HU from the fixed base 60 of the upper HU (described later) and is an operating portion for which a handle or the gripping portion of an actuator is attached.

[0060] Next, the pivot shaft 43 will be described. The pivot shaft 43, which together with the valve stem body 41 and the transmission member 42 constitutes the valve stem unit 40, is formed in a substantially cylindrical shape having a predetermined length in the height direction H, with the upper side HU being slightly smaller in diameter than the lower side HD.

[0061] The transmission member 42, which together with the valve stem body 41 and pivot shaft 43 described above, constitutes the valve stem unit 40. As shown in Figure 7, it is formed in a roughly C-shape when viewed from the horizontal direction, consisting of a pair of plate-shaped horizontal transmission sections 421 spaced apart at a predetermined distance in the height direction H and arranged substantially parallel to each other in the horizontal direction, and a vertical connecting section 422 that connects the horizontal transmission sections 421 in the height direction H. The inner portion of the roughly C-shaped transmission member 42 is formed into a recessed shape that, when viewed from the horizontal direction, becomes substantially circular when combined with the vertical recess 532 of the valve body support section 52, which will be described later.

[0062] The transmission horizontal section 421 consists of an upper transmission horizontal section 421U in the upper HU direction and a lower transmission horizontal section 421D in the depth direction D. The upper transmission horizontal section 421U and the lower transmission horizontal section 421D have the same main configuration and are arranged in an up-and-down symmetrical orientation.

[0063] First, the upper horizontal transmission portion 421U shown in Figure 8(a) will be described. The upper horizontal transmission portion 421U has a fitting hole 44 that penetrates in the height direction H near the center in a plan view, into which the rectangular fitting portion 411 of the valve stem body 41 fits, and is formed in the shape of a substantially flat plate with a predetermined thickness.

[0064] The fitting hole 44 is a square-shaped through-hole that is slightly larger than the planar shape of the rectangular fitting portion 411, into which the rectangular fitting portion 411, which has a square shape when viewed from the bottom, fits. The center P of this fitting hole 44 coincides with the center of the valve stem body 41 and is the rotational center of the valve stem unit 40.

[0065] The upper horizontal transmission section 421U is formed as a flat plate extending from the upper end of the vertical connecting section 422 to the right WR, and forms the aforementioned cam shape with respect to the imaginary square line S, by partially protruding and partially cut out in a plan view.

[0066] More specifically, the upper horizontal transmission section 421U has a triangular projection 423 in plan view that protrudes toward the rear DB relative to the imaginary line S, and also has an inclined notch 424 cut out along the hypotenuse of the right side WR of the triangular projection 423, and an arc-shaped section 425 that arc-shapedly connects the inclined notch 424 and the section along the left side WL of the imaginary line S.

[0067] Furthermore, the upper horizontal transmission portion 421U has a notched portion 427 at a position opposite to the arc-shaped portion 425 that straddles the center P of the fitting hole 44. In the horizontal transmission portion 421, the tip portion along the right side WR of the dashed line S is designated as a rotational transmission portion 426 that transmits the first rotation of the valve stem unit 40 to the valve body unit 50.

[0068] The triangular projection 423 has a corner that is approximately right-angled to the rear side DB and is formed in the shape of an approximately right-angled isosceles triangle that is symmetrical in the width direction W. The inclined notch 424 is formed in the shape of a notch having a straight surface extending from the hypotenuse of the left side WL of the triangular projection 423 and is inclined at an angle of 45 degrees to the right side of the imaginary line S.

[0069] The arc-shaped portion 425 connects the inclined notch portion 424 and the rotation transmission portion 426, and is formed in a smooth curve shape, with the length from the center P of the fitting hole 44 becoming longer towards the rear DB. This will be explained in more detail below. As shown in Figure 8(a), the rotation transmission portion 426 to which the front side DF of the arc-shaped portion 425 is connected is separated by a first perpendicular distance Ar1 from the center P, and the inclined notch portion 424 to which the rear side DB of the arc-shaped portion 425 is connected is separated by a second perpendicular distance Ar2 from the center P. The second perpendicular distance Ar2 is longer than the first perpendicular distance Ar1. Therefore, the arc-shaped portion 425, to which the front side DF is connected to the rotation transmission portion 426 and the rear side DB is connected to the inclined notch portion 424, is a smooth curve shape that gradually changes from the first perpendicular distance Ar1 to the second perpendicular distance Ar2. The difference between the length of the second perpendicular distance Ar2 and the length of the first perpendicular distance Ar1 represents the amount of movement of the valve body unit 50 in the depth direction D, which will be described later.

[0070] Furthermore, the arc-shaped portion 425, in which the front DF connects to the rotation transmission portion 426 and the rear DB connects to the inclined notch portion 424, is formed in a range where the angle θ1 with respect to the center P is 45 degrees. Therefore, the inclined notch portion 424 to which the arc-shaped portion 425 connects and the rotation transmission portion 426 are oriented 45 degrees differently with respect to the center P.

[0071] The notch portion 427 is a notch having an arc-shaped notched arc portion 428 and a portion that extends linearly from the end of the notched arc portion 428 toward the front side DF. More specifically, the notch portion 427 is rotatably cut out so that the locking claw portion 543 of the valve body unit 50, which rotates relative to the valve stem unit 40 as the valve stem unit 40 rotates in conjunction with the second rotation of the valve stem unit 40, as will be described later.

[0072] The notched arc portion 428 is formed in a curved shape, with its length increasing towards the rear DB from the center P of the fitting hole 44. In the state shown in Figure 8(a), the straight portion of the transmission horizontal portion 421 along the imaginary line S of the right WR and rear DB is designated as the locked portion 429 to which the locking claw portion 543, described later, will engage.

[0073] Further details are provided below. The notched circular arc portion 428, which extends from the locked portion 429 towards the front side DF, is formed in a smooth curved shape, with the length from the center P of the fitting hole 44 becoming longer as it approaches the back side DB.

[0074] More specifically, as shown in Figure 8(a), the front end of the notched arc portion 428 is separated by a third perpendicular distance Ar3 from the center P, and the front end of the locked portion 429 to which the rear DB of the notched arc portion 428 is connected is separated by a fourth perpendicular distance Ar4 from the center P. The fourth perpendicular distance Ar4 is longer than the third perpendicular distance Ar3. Therefore, the notched arc portion 428, which connects the rear DB to the locked portion 429 and extends toward the front DF, has a smooth curved shape, gradually decreasing from the fourth perpendicular distance Ar4 to the third perpendicular distance Ar3. The difference in length between the fourth perpendicular distance Ar4 and the third perpendicular distance Ar3 is the same as the difference in length between the second perpendicular distance Ar2 and the first perpendicular distance Ar1.

[0075] Furthermore, the notched circular arc portion 428 is formed in the same manner as the arc-shaped portion 425, in a range where the angle θ2 with respect to the center P is 45 degrees. In the transmission horizontal portion 421 configured in this way, the transmission contact surface 421a that abuts against the valve body vertical portion 53 of the valve body unit 50 during the first rotation is formed on the end face of the rotation transmission portion 426.

[0076] As described above, the lower horizontal transmission section 421D of the lower HD has the same main configuration as the upper horizontal transmission section 421U and is vertically symmetrical, but as shown in Figure 8(b), instead of the fitting hole 44 of the upper horizontal transmission section 421U, a circular pivot hole 45 is provided through which the upper end of the pivot shaft 43 can be inserted. The vertical connecting section 422 that connects the horizontal transmission sections 421 (421U, 421D) configured in this way in the height direction H is formed in a shape that is curved in a circular shape when viewed from the horizontal direction.

[0077] As shown in Figure 6, the valve body unit 50 consists of a roughly disc-shaped metal valve body 51 and a valve body support portion 52 that supports the valve body 51 and is formed in a rectangular C-shape when viewed from the horizontal. The valve body 51 is a roughly spherical disc with a diameter slightly larger than the flow opening 13 of the valve casing 10, and is erected so that its central axis is in the horizontal direction (see Figure 14). In the state shown in Figure 6, the valve body 51 is formed flat at the rear side DB and slightly narrows in diameter towards the front side DF.

[0078] The valve body support portion 52 is a base to which the flat portion of the valve body 51 is fixed by bolts (not shown), and which rotates and moves the valve body 51 in conjunction with the rotation of the valve stem unit 40. It is formed in an inverted rectangular C shape when viewed from the horizontal direction, sandwiching the transmission member 42 from the outside in the height direction H.

[0079] As shown in Figure 9, the valve support portion 52 consists of a vertical valve portion 53 that extends in the height direction H and to which the valve body 51 is fixed, and horizontal valve portions 54 provided on both sides of the vertical valve portion 53 in the height direction H, through which the valve stem body 41 or pivot shaft 43 is inserted.

[0080] The vertical valve body portion 53 is formed in a rectangular shape with a width shorter than the diameter of the valve body main body 51 and a height H longer than the diameter of the valve body main body 51. A valve body mounting location 531 for attaching the valve body main body 51 is provided in the center of the vertical valve body portion 53 (see Figure 6(b)).

[0081] The vertical portion 53 of the valve body has a vertical recess 532 formed in the inner part of the rectangular C-shaped valve body support portion 52, which is curved when viewed from the horizontal. This vertical recess 532 is formed so that, when the valve is open, it forms a roughly circular shape when viewed from the horizontal, together with the inner part of the transmission member 42 described above (see Figure 2(b)).

[0082] The horizontal portion 54 of the valve body is provided with a roughly barrel-shaped projection 541 that protrudes upward HU, and an oval-shaped through-hole 542 is formed inside the barrel-shaped projection 541, penetrating the horizontal portion 54 of the valve body in the height direction H. Furthermore, the horizontal portion 54 of the valve body is provided with a claw-shaped locking claw portion 543 that engages with the transmission horizontal portion 421.

[0083] The barrel-shaped projection 541 is located in the center of the horizontal portion 54 of the valve body and is a projection that loosely fits into the regulating groove 63 of the fixed base 60, which will be described later. In the state shown in Figure 10(a), it has a barrel-shaped outer shape in plan view, with both ends of a rectangle extending in the width direction W being chamfered in an arc shape.

[0084] More specifically, the barrel-shaped projection 541 is provided on both sides in the width direction W, and is formed in a barrel shape in plan view by an arc-shaped portion 541a, 541b that is convex outward in the width direction W, and a straight portion 541c that connects the arc-shaped portions 541a, 541b and runs along the width direction W.

[0085] Furthermore, the large-diameter arc-shaped portion 541a of the right-side WR is formed with a diameter slightly larger than the small-diameter arc-shaped portion 541b of the left-side WL. Although the large-diameter arc-shaped portion 541a and the small-diameter arc-shaped portion 541b have different diameters, they are centered on the same central point.

[0086] The oval through-hole 542 is formed to allow the valve stem body 41 of the valve stem unit 40 to pass through, and is an elongated hole that allows relative movement of the valve stem body 41, and is formed in a position corresponding to the fitting hole 44 of the valve stem unit 40 (see Figure 14). This oval through-hole 542 is an oval-shaped through-hole in plan view, composed of an arc portion that is slightly larger in diameter than the cylindrical portion above the valve stem body 41, and a straight portion that has a length and width W corresponding to the amount of movement between the valve body unit 50 and the valve stem body 41.

[0087] The locking claw portion 543 is a locking piece that extends from the rear DB and left WL of the horizontal portion 54 of the valve body to the lower HD. When the valve is open, it locks onto the locked portion 429, and when the valve is closed, it is positioned in the notched portion 427 of the valve stem unit 40.

[0088] As shown in Figure 6, the fixed base 60 consists of a flat base body 61 fixed to the valve body 10 and a cylindrical projection 62 that protrudes from the base body 61 in the height direction H. The fixed base 60 is arranged on both sides of the valve body 10 in the height direction H and is positioned symmetrically in the height direction H. The following description will focus on the fixed base 60 located on the upper side HU.

[0089] Furthermore, the fixed base 60 positioned on the upper HU of the valve box 10 has a cylindrical projection 62 extending from the bottom surface of the base body 61 toward the lower HD, and the fixed base 60 positioned on the lower HD of the valve box 10 has a cylindrical projection 62 extending from the top surface of the base body 61 toward the upper HU.

[0090] The base body 61 is configured to be fastened and fixed to the end face in the height direction H of the valve body 10, which is roughly square in plan view, with bolts (not shown). The cylindrical projection 62 is formed in a roughly cylindrical shape with a diameter that allows the through hole 11 to be inserted, and as shown in Figure 3, when the fixing base 60 is attached to the valve body 10, it is formed at a height where the tip reaches the flow path F.

[0091] A stepped, reduced-diameter portion 621 is provided on the side surface of the cylindrical projection 62, and an annular sealing member (O-ring) is attached to the reduced-diameter portion 621 to seal the space between it and the valve body 10 when inserted through the through hole 11. As shown in Figure 11, a regulating groove 63 is formed on the tip surface of the cylindrical projection 62, into which the barrel-shaped projection 541 of the valve body unit 50 is loosely fitted, thereby restricting the rotation range and movement of the valve body unit 50. This regulating groove 63 is a circular recess in bottom view, formed on the bottom surface of the cylindrical projection 62, with a portion of its diameter expanding outward in the circumferential direction.

[0092] More specifically, the regulating groove 63 has a small-diameter rotating groove 631 that follows the small-diameter arc-shaped portion 541b of the barrel-shaped projection 541, which rotates 90 degrees from the open state, with the valve stem body 41 inserted through the oval through hole 542 of the valve body unit 50 as the axis of rotation, a large-diameter rotating groove 632 that follows the large-diameter arc-shaped portion 541a, and a movement-allowing portion 633 that protrudes from the large-diameter rotating groove 632 toward the front side DF when rotated 90 degrees, allowing relative movement of the barrel-shaped projection 541 toward the front side DF.

[0093] The small-diameter rotating groove portion 631 is formed in a substantially semicircular shape with substantially the same diameter as the small-diameter arc-shaped portion 541b of the barrel-shaped projection portion 541, while the large-diameter rotating groove portion 632 and the movable allowance portion 633 are formed in a substantially quarter-circular shape with substantially the same diameter as the large-diameter arc-shaped portion 541a. Although the small-diameter rotating groove portion 631 and the large-diameter rotating groove portion 632 have different diameters, they are centered at the same central point. In contrast, the movable allowance portion 633, which allows relative movement of the barrel-shaped projection portion 541 toward the front side DF, is centered at a position eccentric to the front side DF relative to the large-diameter rotating groove portion 632.

[0094] The small-diameter rotating groove 631, the large-diameter rotating groove 632, and the movable allowance 633 are arranged in this order in the circumferential direction. A first stepped portion 634 is formed radially between the small-diameter rotating groove 631 and the large-diameter rotating groove 632. A second stepped portion 635 is formed along the depth direction D between the large-diameter rotating groove 632 and the movable allowance 633. A third stepped portion 636 is formed along the depth direction D between the movable allowance 633 and the small-diameter rotating groove 631. The second stepped portion 635 and the third stepped portion 636 are parallel as they are both along the depth direction D, but the third stepped portion 636 is formed to be longer than the second stepped portion 635.

[0095] The aforementioned regulating groove 63 is formed on the bottom surface of the cylindrical projection 62 of the fixed base 60 located on the upper HU of the valve body 10, and is also formed on the upper surface of the cylindrical projection 62 of the fixed base 60 located on the lower HD of the valve body 10.

[0096] In the fixed base 60 positioned on the upper HU of the valve body 10, a cylindrical projection 62 has a through hole 64 formed in the center of its plan view. This through hole penetrates in the height direction H, allowing the enlarged portion 412 of the valve stem body 41 to be inserted. The through hole 64 is a through-hole through which the upper HU narrows by one step, and the diameter of the narrowed portion is smaller than that of the enlarged portion 412 (see Figure 3). The fixed base 60 of the upper HU is also equipped with an anti-extraction body 66 to prevent the inserted valve stem body 41 from coming out (see Figure 3).

[0097] In contrast, in the fixed base 60 positioned on the lower HD of the valve body 10, a mounting recess 65 is formed in the center of the cylindrical projection 62 in a plan view, instead of an insertion hole 64, so that a pivot shaft 43 can be attached (see Figures 3 and 6).

[0098] As described above, the valve stem unit 40, valve body unit 50, and fixed base 60, each composed of various elements, are assembled to form the opening and closing mechanism Y. Specifically, the transmission member 42 and the valve body support portion 52 are assembled such that the horizontal valve body portion 54 is positioned on the outside of the horizontal transmission portion 421 in the height direction H, and the inner portion of the vertical connecting portion 422 and the vertical recess portion 532 form a circle when viewed from the horizontal direction. The locking claw portion 543 is assembled to engage with the locking portion 429.

[0099] Then, the pivot shaft 43, which is attached to the mounting recess 65 of the fixed base 60 of the lower HD, is inserted from the lower HD into the oval through hole 542 and pivot hole 45 of the lower HD, which are in communication with each other. At this time, the barrel-shaped projection 541 of the valve body unit 50 is loosely fitted into the regulating groove 63 of the fixed base 60 of the lower HD.

[0100] Furthermore, the lower end of the valve stem body 41 is inserted through the oval through hole 542 and fitting hole 44 of the upper HU, which are in communication with each other, and the rectangular fitting portion 411 is fitted with the fitting hole 44 of the transmission member 42. Then, the upper end of the valve stem body 41 is inserted through the insertion hole 64 of the fixing base 60 of the upper HU. At this time, the barrel-shaped projection 541 of the valve body unit 50 is loosely fitted into the regulating groove 63 of the fixing base 60 of the upper HU.

[0101] Thus, in the initial state, the opening and closing mechanism Y, which is assembled by combining the valve stem unit 40, the valve body unit 50, and the fixed base 60, has the transmission contact surface 421a of the rotational transmission portion 426 of the transmission horizontal portion 421 of the transmission member 42 constituting the valve stem unit 40 in contact with the back surface of the vertical portion 53 of the valve body in the valve body support portion 52 constituting the valve body unit 50.

[0102] Furthermore, in the initial state of the opening / closing mechanism Y, the valve body unit 50 rotates with the first rotation of the valve stem unit 40, and the valve body unit 50 moves to the front side DF with the second rotation of the valve stem unit 40. At this time, the transmission contact surface 421a of the inclined notch portion 424 in the transmission horizontal portion 421 of the transmission member 42 constituting the valve stem unit 40 comes into contact with the back surface of the valve body vertical portion 53 in the valve body support portion 52 constituting the valve body unit 50.

[0103] Conversely, in the opening / closing mechanism Y, the valve body unit 50, which is in the position moved to the front side DF, moves to the rear side DB as the valve stem unit 40 rotates in the reverse direction for the second time, and the valve body unit 50 rotates in the reverse direction as the valve stem unit 40 rotates in the reverse direction for the first time, returning to the initial state.

[0104] More specifically, as described above, the opening and closing mechanism Y, with its barrel-shaped projection 541 and the regulating groove 63 into which the barrel-shaped projection 541 loosely fits, functions as a rotation regulating mechanism MR that allows the rotation of the valve body unit 50 in conjunction with the first rotation of the valve stem unit 40, and restricts the rotation of the valve body unit 50 in the second rotation of the valve stem unit 40, but allows it to move toward the front side DF.

[0105] At this time, the transmission member 42 of the valve stem unit 40, which rotates beyond the first rotation, rotates relative to the valve body unit 50 because the rotation of the valve body unit 50 is restricted. As a result, the arc-shaped portion 425 of the valve stem unit 40 presses against the vertical portion 53 of the valve body of the valve body unit 50, functioning as a rotational movement conversion mechanism MD that moves the valve body unit 50 in the depth direction D.

[0106] Conversely, in the opening / closing mechanism Y, the barrel-shaped projection 541 and the regulating groove 63, which function as a rotation regulating mechanism MR, allow the valve body unit 50, which has moved to the front side DF due to the second reverse rotation of the valve stem unit 40, to move to the rear side DB, and allow the rotation of the valve body unit 50 accompanying the first reverse rotation of the valve stem unit 40.

[0107] At this time, the transmission member 42 of the valve stem unit 40, which rotates in the opposite direction to the valve body unit 50 that has been restricted from rotating and moved to the front side DF, rotates relative to the valve body unit 50. As a result, the notched portion 427 of the valve stem unit 40 presses against the locking claw portion 543 of the valve body unit 50, functioning as a rotational reverse movement conversion mechanism RD that moves the valve body unit 50 to the rear side DB. The rotation restricting mechanism MR, the rotational movement conversion mechanism MD, and the rotational reverse movement conversion mechanism RD configured in this way are arranged on both sides in the height direction H with the valve body 51 in between.

[0108] The opening and closing mechanism Y, which is configured and functions as described above, is assembled to the main body mechanism X such that the valve body 51 is positioned in the flow path F in the main body mechanism X (see Figure 3). More specifically, the opening and closing mechanism Y is assembled to the valve casing 10 that constitutes the main body mechanism X such that the movable allowable portion 633 of the regulating groove 63 provided on the fixed base 60 is located on the side of the valve seat 30, thereby forming the butterfly valve 1.

[0109] At this time, the cylindrical projection 62 of the fixed base 60 is inserted through the through hole 11 of the valve body 10 and fastened to the valve body 10 with bolts (not shown), and the opening / closing mechanism Y is assembled to the main body mechanism X. With the main body mechanism X and the opening / closing mechanism Y assembled in this way, the butterfly valve 1 allows the valve stem unit 40 to be rotated by operating the valve stem body 41 to which a handle or actuator is attached. As the valve stem unit 40 rotates, the valve body unit 50 can be rotated or moved relative to it.

[0110] Next, the operation of the butterfly valve 1, which has the main body mechanism X and the opening / closing mechanism Y assembled, and the rotational movement conversion mechanism MD and the rotational regulating mechanism MR, will be explained with reference to Figure 14. Figures 14(a) to 14(c) show the open state with the valve stem unit 40 rotated most counterclockwise, Figures 14(d) to 14(f) show the state after the valve stem unit 40 has been rotated one full turn from the open state, Figures 14(f) to 14(i) show the state after the valve stem unit 40 has been rotated 115 degrees clockwise from the open state, and Figures 14(j) to 14(l) show the state after the valve stem unit 40 has been rotated a second full turn, that is, the closed state with the valve stem unit 40 rotated most clockwise.

[0111] In other words, the butterfly valve 1 can be switched from the open state, where the valve stem unit 40 is rotated most counterclockwise, to the closed state, where the valve stem unit 40 is rotated most clockwise, by rotating the valve stem unit 40 by 135 degrees.

[0112] Furthermore, the view taken along the line C-C in Figure 3(a), shown in Figures 14(a), (d), (g), and (j), illustrates the state in which the barrel-shaped projection 541 is loosely fitted into the regulating groove 63, that is, the state of the rotation regulating mechanism MR. Also, the view taken along the line D-D in Figure 3(a), shown in Figures 14(b), (e), (h), and (k), illustrates the rotation and movement of the valve body unit 50 accompanying the rotation of the valve stem unit 40, that is, the rotational movement conversion mechanism MD and the rotational reverse movement conversion mechanism RD. In addition, the view taken along the line E-E in Figure 3(a), shown in Figures 14(c), (f), (i), and (l), illustrates the state of the valve body 51 of the valve body unit 50 in the flow path F.

[0113] In Figure 14, the left-right direction represents the width direction W, with the left side representing the left WL and the right side representing the right WR. Also in Figure 14, the up-down direction represents the depth direction D, with the downward direction representing the front side DF and the upward direction representing the back side DB.

[0114] The operation of the butterfly valve 1 from the open valve state shown in Figures 14(a) to (c) to the closed valve state shown in Figures 14(j) to 14(l) will be described below in more detail, the operation of the rotational movement conversion mechanism MD, the rotational regulating mechanism MR, and the valve body unit 50 from the open valve state to the closed valve state.

[0115] In the open valve state, which is the initial state in this specification, as shown in Figures 2(a), 2(b), 4(a), 5(a), and 14(a) to 14(c), the valve body 51 attached to the vertical valve portion 53 of the valve body unit 50 is positioned to face the right WR in the flow path F of the valve casing 10. The valve stem unit 40 and the valve body unit 50 are positioned so that the vertical connecting portion 422 and the vertical valve portion 53 face each other in the width direction W. As a result, the transmission member 42 of the valve stem unit 40 and the vertical recess 532 of the valve body unit 50 form a frame with a circular opening having an axis along the depth direction D. Therefore, in the butterfly valve 1, the fluid passing through the flow path F can flow through the flow opening 13.

[0116] In this state, the rotation restricting mechanism MR is positioned in the restricting groove 63 such that the barrel-shaped projection 541 has its long axis aligned with the width direction W. In this state, the rotation restricting mechanism MR does not restrict the clockwise rotation of the valve body unit 50. Therefore, when the valve stem unit 40 is rotated clockwise by a predetermined angle of 90 degrees from the open valve state, that is, as the valve stem unit 40 makes its first rotation, the valve body unit 50, which has a vertical valve body portion 53 that the transmission contact surface 421a of the rotation transmission portion 426 of the valve stem unit 40 contacts, rotates clockwise by 90 degrees (see Figures 14(d) to 14(f)). When rotating clockwise by a predetermined angle of 90 degrees from the open valve state, the small-diameter arc-shaped portion 541b of the barrel-shaped projection 541 rotates along the small-diameter rotation groove portion 631 of the restricting groove 63, and the large-diameter arc-shaped portion 541a rotates along the large-diameter rotation groove portion 632.

[0117] When it rotates to 90 degrees, the barrel-shaped projection 541 comes into contact with the side wall of the small-diameter rotating groove 631 of the restricting groove 63, and the rotation restricting mechanism MR restricts further clockwise rotation of the valve body unit 50. In detail, as shown in Figure 14(b), the straight portion 541c on the large-diameter arc-shaped portion 541a side of the barrel-shaped projection 541 comes into contact with the third stepped portion 636 between the movable allowable portion 633 and the small-diameter rotating groove 631, thereby restricting further clockwise rotation of the valve body unit 50.

[0118] As described above, with the rotation restricting mechanism MR preventing further clockwise rotation of the valve body unit 50, if the valve stem unit 40 is rotated to a further 115-degree rotation position, the transmission member 42 of the valve stem unit 40 rotates in such a way that it presses the vertical portion 53 of the valve body of the valve body unit 50 against the front side DF (see Figures 14(g) to 14(i)).

[0119] More specifically, the arc-shaped portion 425 of the cam-shaped transmission horizontal portion 421 becomes longer towards the rear DB, so as the valve stem unit 40 rotates, it presses the valve body unit 50 toward the front DF. At this time, the barrel-shaped projection 541 of the valve body unit 50 moves the movable allowance portion 633 of the regulating groove 63 toward the front DF.

[0120] Specifically, as shown in Figure 14(g), the straight portion 541c of the barrel-shaped projection 541 moves along the second stepped portion 635 and the third stepped portion 636, while the barrel-shaped projection 541 moves the movable allowable portion 633 toward the front side DF. Furthermore, the locking claw portion 543 of the valve body unit 50 rotates to be positioned from the locked portion 429 of the valve stem unit 40 to the arc portion of the notched portion 427.

[0121] In this state, if the valve stem unit 40 is further rotated to the 135-degree rotation position, the valve body unit 50 is pushed further toward the front side DF by the transmission member 42 of the valve stem unit 40 (see Figures 14(j) to 14(l)).

[0122] At this time, the barrel-shaped projection 541 of the valve body unit 50 is fitted into the movable allowable portion 633 of the restricting groove 63, that is, it is fitted between the second stepped portion 635 and the third stepped portion 636, thereby restricting further clockwise rotation of the valve stem unit 40 and the valve body unit 50.

[0123] Furthermore, the transmission contact surface 421a of the inclined notch portion 424 of the triangular projection portion 423 of the valve stem unit 40 contacts the vertical portion 53 of the valve body unit 50, thereby preventing the valve body unit 50 from unintentionally moving to the rear side DB.

[0124] In this way, the further rotation of the valve stem unit 40, that is, the second rotation, causes the transmission member 42 to push the valve body unit 50 toward the front side DF, so that the valve body 51 of the valve body unit 50 moves toward the front side DF, and the valve body 51 comes into close contact with the valve seat 30 attached to the mounting portion 12, thereby sealing the flow opening 13.

[0125] Thus, the valve stem unit 40 was rotated 135 degrees clockwise from the initial open valve state to the closed valve state. From this closed valve state, the valve stem unit 40 can be rotated 135 degrees counterclockwise to return to the open valve state.

[0126] Specifically, when the valve stem unit 40 is rotated 115 degrees counterclockwise from the closed valve position, the locking claw portion 543 of the valve body unit 50 located in the notch portion 427 rotates along the notched arc portion 428 and is pressed against the rear DB by the notched arc portion 428 (see Figures 14(g) to 14(l)). As a result, the valve body 51 is pulled into the rear DB, and the contact between the valve body 51 and the valve seat 30 is released.

[0127] At this time, the small-diameter arc-shaped portion 541b of the barrel-shaped projection 541, which was fitted into the movable allowance portion 633, disengages from the movable allowance portion 633. More specifically, one side of the straight portion 541c of the barrel-shaped projection 541 is aligned with the third stepped portion 636 that constitutes the movable allowance portion 633, but the other side of the straight portion 541c disengages from the second stepped portion 635, resulting in a state where counterclockwise rotation is permitted.

[0128] Furthermore, when the valve stem unit 40 is rotated in the reverse direction for the second time, the locking claw portion 543 engages with the locked portion 429, and the small-diameter arc-shaped portion 541b of the barrel-shaped projection 541 of the valve body unit 50 is positioned in the small-diameter rotating groove portion 631 of the regulating groove 63 (see Figures 14(d) to 14(f)).

[0129] Then, by further rotating the valve stem unit 40 in the reverse direction for the first time, the valve body unit 50 can be rotated to the open position, thereby opening the butterfly valve 1. Specifically, in the reverse first rotation of the valve stem unit 40, the small-diameter arc-shaped portion 541b of the barrel-shaped projection 541 follows the small-diameter rotating groove portion 631, and the large-diameter arc-shaped portion 541a rotates along the large-diameter rotating groove portion 632, and it can rotate until the straight portion 541c on the large-diameter arc-shaped portion 541a side comes into contact with the first stepped portion 634. Since the straight portion 541c on the large-diameter arc-shaped portion 541a side comes into contact with the first stepped portion 634, further counterclockwise rotation can be restricted.

[0130] In this way, the notched arc portion 428 and the locked portion 429 of the valve stem unit 40 and the locking claw portion 543 of the valve body unit 50 function as a rotational reverse movement conversion mechanism RD that separates the valve seat 30 by the second reverse rotation of the valve stem unit 40 and rotates the valve body unit 50 in the first reverse rotation by the first reverse rotation of the valve stem unit 40.

[0131] As described above, the butterfly valve 1 includes a valve body 10 having a tubular flow path F, a valve stem unit 40 that is rotatable around a valve stem body 41 relative to the valve body 10, a valve body unit 50 that rotates due to the rotation of the valve stem unit 40 to open and close the flow path F, and a valve seat 30 provided between the valve body 10 and the valve body unit 50 for sealing. Furthermore, the valve is provided with a rotation restricting mechanism MR which defines the rotation from the open position to the 90-degree rotated position as the first rotation, and the rotation of the valve stem unit 40 from the 90-degree rotated position to the closed position as the second rotation, allowing the first rotation of the valve body unit 50, restricting the rotation of the valve body unit 50 accompanying the second rotation of the valve stem unit 40, and allowing the movement of the valve body unit 50 on the front side DF that is in close contact with the valve seat 30, and a rotation movement conversion mechanism MD which moves the valve body unit 50 so that it is in close contact with the valve seat 30 by the second rotation of the valve stem unit 40 relative to the valve body unit 50 whose rotation is restricted by the rotation restricting mechanism MR.

[0132] The rotational movement conversion mechanism MD is provided on the valve stem unit 40 and has an arc-shaped portion 425 that, upon the second rotation of the valve stem unit 40, contacts the valve body unit 50 and moves the valve body 51 of the valve body unit 50 so that it is in close contact with the valve seat 30. The arc-shaped portion 425 is convex in diameter and has a longer axis than the rotation transmission portion 426 that contacts the valve body unit 50 upon the first rotation of the valve stem unit 40. As a result, a stable and high compression pressure can be obtained, and the flow path F can be reliably shut off.

[0133] More specifically, the butterfly valve 1 is equipped with a rotation restricting mechanism MR that allows the valve body unit 50 to rotate once, restricts the rotation of the valve body unit 50 accompanying the second rotation of the valve stem unit 40, and allows the movement of the valve body unit 50 in the direction toward close contact with the valve seat 30. Therefore, the rotation restricting mechanism MR allows the valve body unit 50 to rotate once from the open position to the 90-degree rotated position in conjunction with the first rotation of the valve stem unit 40 from the open position to the 90-degree rotated position.

[0134] Furthermore, the butterfly valve 1 is provided with a rotational movement conversion mechanism MD that moves the valve body unit 50 so that it is in close contact with the valve seat 30 by the second rotation of the valve stem unit 40 relative to the valve body unit 50 whose rotation is restricted by the rotational movement restriction mechanism MR. The rotational movement conversion mechanism MD is also provided on the valve stem unit 40 and has an arc-shaped portion 425 that is convex in the circumferential direction, with a portion of it having a longer diameter than the rotational transmission portion 426.

[0135] Therefore, even if the valve stem unit 40 rotates a second time, the rotation of the valve body unit 50, which has rotated a first time, will be restricted by the rotation restricting mechanism MR. However, the rotational movement conversion mechanism MD has an arc-shaped portion 425 provided on the valve stem unit 40. Therefore, as the valve stem unit 40 rotates a second time, the arc-shaped portion 425 comes into contact with the valve body unit 50, causing the valve body unit 50 to move so that it is in close contact with the valve seat 30.

[0136] Therefore, in the closed state, the valve body unit 50 and the valve seat 30 are in close contact under high compressive pressure. Consequently, even when blocking the flow of fluids with small molecular sizes or fluids at extremely low temperatures such as cryogenic temperatures, the fluid will not leak out from between the valve body unit 50 and the valve seat 30, and the flow path F can be reliably blocked.

[0137] Furthermore, the valve stem unit 40 is provided with a transmission member 42 having a transmission horizontal section 421 that transmits the first rotation of the valve stem unit 40 to the valve body unit 50, and a pivot shaft 43 is provided along the valve stem body 41 that rotatably supports the transmission member 42 on the side opposite to the valve stem unit 40 relative to the valve body unit 50.

[0138] Therefore, the pivot shaft 43, which is provided along the valve stem body 41 on the opposite side of the valve body unit 50 from the valve stem unit 40, allows the valve body unit 50, which rotates in conjunction with the first rotation of the valve stem unit 40, to rotate stably. Furthermore, the rotational force of the valve stem unit 40 in the first rotation is reliably transmitted to the valve body unit 50 by the transmission member 42, so that the valve body unit 50 can be reliably rotated by the first rotation of the valve stem unit 40.

[0139] Furthermore, the transmission horizontal section 421, the rotation restricting mechanism MR, and the rotational movement conversion mechanism MD are provided on both sides of the valve body unit 50 in the height direction H along the valve stem body 41. As a result, the transmission horizontal section 421, the rotation restricting mechanism MR, and the rotational movement conversion mechanism MD, provided on both sides in the height direction H, can stably restrict the rotation of the valve body unit 50 accompanying the second rotation of the valve stem unit 40, compared to the case where they are provided on only one side in the height direction H, while the rotational movement conversion mechanism MD can move the valve body unit 50 in a direction that brings it into close contact with the valve seat 30, thereby reliably blocking the flow path F when the valve is closed.

[0140] Furthermore, since a pivot shaft 43 is provided along the valve stem body 41, rotatably supporting the transmission member 42 on the side opposite to the valve stem unit 40 relative to the valve body unit 50, the rotational movement conversion mechanism MD, which is located on the side opposite to the valve stem unit 40 relative to the valve body unit 50, can be reliably activated in the closed valve state, thereby more reliably blocking the flow path F.

[0141] Furthermore, the arc-shaped portion 425 is provided on the transmission member 42, and the transmission member 42 is provided with a planar triangular projection 423 that contacts the valve body unit 50 in order to maintain the state in which the valve body unit 50 is in close contact with the valve seat 30, and the transmission horizontal portion 421 has a planar transmission contact surface 421a that contacts the valve body unit 50, and the transmission contact surface 421a, the arc-shaped portion 425 and the triangular projection 423 are provided in this order from the front of the rotation to the rear of the rotation in a clockwise direction from the first rotation to the second rotation.

[0142] Therefore, the transmission contact surface 421a that contacts the valve body unit 50 can reliably transmit the first rotation of the valve stem unit 40 to the valve body unit 50, and the triangular projection 423 can maintain a state in which the valve body 51 of the valve body unit 50 is in close contact with the valve seat 30.

[0143] Furthermore, since the transmission contact surface 421a, the arc-shaped portion 425, and the triangular projection portion 423 are arranged in this order from the front to the rear of rotation in a clockwise direction, the valve body unit 50, which has been rotated by the first rotation of the valve stem unit 40, can be pressed against the valve seat 30 by the arc-shaped portion 425 during the second rotation of the valve stem unit 40, and the triangular projection portion 423 can maintain the tight seal of the valve body unit 50 against the valve seat 30.

[0144] In this way, by simply rotating the valve stem unit 40 clockwise from the open valve position, the valve body unit 50 can be reliably rotated, and the state in which the valve body unit 50 is in close contact with the valve seat 30 can be reliably maintained.

[0145] Furthermore, the transmission member 42 is provided with a vertical connecting portion 422 that is positioned in a predetermined direction away from the valve stem body 41 to suppress the reduction of the flow area in the open valve state. As a result, without reducing the flowability in the open valve state, the valve body unit 50 can be moved in a direction that brings it into close contact with the valve seat 30 by the rotational movement conversion mechanism MD in the closed valve state, thereby reliably blocking the flow path F.

[0146] Furthermore, the rotation of the valve stem unit 40 from the closed position to the 90-degree rotated position is set to a second reverse rotation, and the rotation from the 90-degree rotated position to the open position is set to a first reverse rotation. The rotational movement conversion mechanism MD moves the valve body unit 50 so that it is in close contact with the valve seat 30, and the second reverse rotation of the valve stem unit 40 moves it away from the valve seat 30, while the first reverse rotation of the valve stem unit 40 rotates the valve body unit 50 to a first reverse rotation. The rotational movement conversion mechanism RD is provided on the valve stem unit 40 and has a notched circular arc portion 428 that comes into contact with the valve body unit 50 due to the second reverse rotation of the valve stem unit 40 relative to the valve body unit 50 in close contact with the valve seat 30, thereby moving the valve body unit 50 away from the valve seat 30.

[0147] Therefore, the closed butterfly valve 1 can be easily opened. More specifically, the butterfly valve 1 is equipped with a rotational movement conversion mechanism RD that moves the valve body unit 50, which has been moved by the rotational movement conversion mechanism MD to be in close contact with the valve seat 30, away from the valve seat 30 by the reverse second rotation of the valve stem unit 40, and also rotates the valve body unit 50 in the reverse first rotation by the reverse first rotation of the valve stem unit 40. Therefore, the butterfly valve 1 can move the valve body unit 50 away from the valve seat 30 by the reverse second rotation of the valve stem unit 40 by the rotational movement conversion mechanism RD, and can also rotate the valve body unit 50 in the reverse first rotation in conjunction with the reverse first rotation of the valve stem unit 40.

[0148] Furthermore, the rotational reverse movement conversion mechanism RD is provided on the valve stem unit 40 and has a notched arc portion 428 that, when the valve stem unit 40 rotates in the opposite direction to the valve body unit 50 which is in close contact with the valve seat 30, comes into contact with the valve body unit 50 and separates the valve body unit 50 from the valve seat 30.

[0149] Therefore, the second reverse rotation of the valve stem unit 40 relative to the valve body unit 50 which is in close contact with the valve seat 30 causes the notched arc portion 428 to come into contact with the locking claw portion 543 of the valve body unit 50, separating the valve body unit 50 from the valve seat 30, and the first reverse rotation of the valve stem unit 40 allows the butterfly valve 1 to be easily opened.

[0150] Furthermore, the rotational reverse movement conversion mechanism RD is provided on both sides of the valve body unit 50 in the direction along the valve stem body 41. Therefore, the rotational reverse movement conversion mechanism RD provided on both sides in the direction along the valve stem body 41 ensures that the valve body unit 50 is reliably separated from the valve seat 30 as the valve stem unit 40 rotates in the reverse second direction, and that the butterfly valve 1 is reliably opened as the valve stem unit 40 rotates in the reverse first direction.

[0151] (Second Embodiment) In the above-described embodiment, the transmission horizontal portion 421 was formed with an asymmetrical external shape, but it may also be formed with symmetry in a planar view with respect to the fitting hole 44 as the axis. Hereinafter, an opening and closing mechanism Y of the second embodiment, having a transmission member 42 having a transmission horizontal portion 421z configured with an external diameter that is point-symmetric with respect to the center P of the fitting hole 44 as the axis, and a valve body unit 50z that is rotated or moved by the transmission member 42, will be described with reference to Figure 15.

[0152] Figure 15 shows a schematic exploded perspective view of the transmission member 42z and the valve body unit 50z. More specifically, Figure 15 shows a schematic exploded perspective view of the back, right side, and top views of the transmission member 42z and the valve body unit 50z when the valve stem unit 40z has been rotated for the first time. Note that components identical to those of the butterfly valve 1 described above are referred to by the same reference numerals and their explanations are omitted.

[0153] As shown in Figure 15, the transmission member 42z is arranged at predetermined intervals in the height direction H and is formed in an inverted, approximately C-shape when viewed from the horizontal direction, consisting of a horizontal transmission portion 421z arranged horizontally and a vertical connecting portion 422 that connects the horizontal transmission portion 421z in the height direction H. The inner portion of the approximately C-shape of the transmission member 42z, together with the vertical recess portion 532, is formed in an arc-shaped plate that is approximately circular when viewed from the horizontal direction.

[0154] The horizontal transmission portion 421z is formed in a cam shape that is rotationally symmetrical with respect to the fitting hole 44. Specifically, the horizontal transmission portion 421z is provided with a triangular projection portion 423, an inclined notch portion 424, and an arc-shaped portion 425, as well as a second triangular projection portion 423z symmetrical to the triangular projection portion 423, a second inclined notch portion 424z symmetrical to the inclined notch portion 424, and a second arc-shaped portion 425z symmetrical to the arc-shaped portion 425. In the horizontal transmission portion 421z, the base end portion that is symmetrical to the rotational transmission portion 426 with respect to the fitting hole 44 is designated as the second rotational transmission portion 426z.

[0155] In the transmission horizontal section 421z configured in this way, when the valve body unit 50z rotates in the reverse second rotation, the separation-maintaining contact surface 421b that maintains the separation state of the valve body unit 50z relative to the valve seat 30 is formed on the base end side of the second rotation transmission section 426z.

[0156] The valve body unit 50z has the same configuration as the valve body unit 50, except that the locking claw portion 543z corresponding to the locking claw portion 543 of the valve body unit 50 extends downward HD from the entire tip of the horizontal portion 54 of the valve body, and the locking claw portion 543z is formed to face the vertical portion 53 of the valve body (see Figure 15). The second triangular projection portion 423z, the second inclined notch portion 424z, and the second arc-shaped portion 425z of the valve stem unit 40z configured in this way, and the locking claw portion 543z of the valve body unit 50z, function as a rotational reverse movement conversion mechanism RD.

[0157] As described above, the transmission member 42z is provided with a transmission horizontal portion 421z that transmits the second reverse rotation of the valve stem unit 40z to the valve body unit 50z, and a planar separation-maintaining contact surface 421b that contacts the valve body unit 50z to maintain the separation state of the valve body unit 50z from the valve seat 30. The second arc-shaped portion 425z is provided on the transmission member 42z, and the transmission horizontal portion 421z has a planar second triangular projection portion 423z that contacts the valve body unit 50z. The separation-maintaining contact surface 421b, the second arc-shaped portion 425z, and the second triangular projection portion 423z are provided in this order from the front of the reverse rotation to the rear of the reverse rotation in a counterclockwise direction from the second reverse rotation to the first reverse rotation.

[0158] Therefore, the second triangular projection 423z of the transmission member 42z reliably transmits the rotational force of the valve stem unit 40z in the reverse second rotation to the valve body unit 50z, and the separation-maintaining contact surface 421b maintains the state in which the valve body unit 50z is separated from the valve seat 30.

[0159] Furthermore, since the separation-maintaining contact surface 421b, the second arc-shaped portion 425z, and the second triangular projection portion 423z are provided in this order from the front to the rear in the counterclockwise direction, simply rotating the valve stem unit 40z counterclockwise from the closed valve state will reliably separate the valve body unit 50z from the valve seat 30 and reliably rotate the valve body unit 50z to reliably maintain the open valve state.

[0160] Furthermore, the rotational reverse movement conversion mechanism RD is located on the opposite side of the valve stem body 41 from the rotational movement conversion mechanism MD. As a result, at least one of the rotational movement conversion mechanism MD and the rotational reverse movement conversion mechanism RD is in contact with the valve body unit 50z, thereby ensuring reliable control of the movement of the valve body unit 50z toward or away from the valve seat 30 due to the rotation of the valve stem unit 40z.

[0161] In the correspondence between the configuration of the present invention and the embodiments described above, the flow path of the present invention corresponds to the flow path F, and similarly, the valve body corresponds to the valve body 10, the valve stem corresponds to the valve stem unit 40, the valve body corresponds to the valve body unit 50, the valve seat corresponds to the valve seat 30, the rotation restricting mechanism corresponds to the rotation restricting mechanism MR, the rotational movement conversion mechanism corresponds to the rotational movement conversion mechanism MD, the cam portion corresponds to the arc-shaped portion 425, the butterfly valve corresponds to the butterfly valve 1, the rotation transmission portion corresponds to the transmission horizontal portion 421, the transmission member corresponds to the transmission member 42, the support shaft corresponds to the pivot shaft 43, the axial direction corresponds to the height direction H, the maintenance contact surface corresponds to the triangular projection portion 423, the transmission contact surface corresponds to the transmission contact surface 421a, the off-center portion corresponds to the vertical connection portion 422, and the rotational reverse movement conversion mechanism corresponds to the rotational reverse movement conversion mechanism RD, however, the present invention is not limited to the embodiments described above.

[0162] For example, although the butterfly valve 1 was a single-element eccentric butterfly valve, it may also be configured as a center-element butterfly valve or a double-element eccentric butterfly valve. Furthermore, in the above description of the butterfly valve 1, the valve stem unit 40 was rotated clockwise to a position 90 degrees from the initial open valve state, and the rotation of the valve body unit 50 was restricted by the rotation restricting mechanism MR. When the rotation exceeds 90 degrees, the arc-shaped portion 425 pressed against the vertical portion 53 of the valve body unit 50, moving the valve body unit 50 to the front side DF and making it tightly contact with the valve seat 30. However, the angle is not limited to the above angle and may be set to an appropriate angle.

[0163] Furthermore, the shape of the regulating groove 63 in the rotation regulating mechanism MR is not limited to the shape described above. For example, the movement-permitting portion 633 may be an opening, and the small-diameter rotating groove portion 631 that restricts the rotation of the barrel-shaped projection 541 may also be composed of a convex portion that protrudes from the inner surface of a circumferential arc frame.

[0164] The valve stem unit 40 is provided with a valve stem body 41 and a pivot shaft 43, but it may also be provided with a single valve stem body that penetrates the transmission member 42 in the height direction H. In this case, the valve stem body may be provided with a offset portion that is shifted in a predetermined direction from the axis, in the portion of the valve stem body that is positioned between the transmission horizontal portions 421 of the transmission member 42.

[0165] Furthermore, in the above description, the rotational movement conversion mechanism MD was used to move the valve body unit 50 toward the front side DF, that is, toward the front side DF, in the direction in which the fluid flows from the rear side DB to the front side DF, and bring it into close contact with the valve seat 30. However, the direction in which the valve body unit 50 moves by the rotational movement conversion mechanism MD does not need to be in line with the direction of fluid flow, and the direction in which the valve body unit 50 and the valve seat 30 come into contact may be in a direction that intersects with the direction of fluid flow.

[0166] Furthermore, in the above description, the arc-shaped portion 425 that serves as the cam portion is provided on the valve stem unit 40 in the rotational movement conversion mechanism MD. However, the cam portion may be provided on the valve body unit 50, and the portion that is pressed against the cam portion may be provided on the valve stem unit 40.

[0167] Furthermore, in the above description, the butterfly valve 1 is configured to switch between an open state, where the valve stem unit 40 is rotated most counterclockwise, and a closed state, where the valve stem unit 40 is rotated most clockwise, by rotating it 135 degrees. However, the butterfly valve 1 may also be configured so that it switches from the open state to the closed state by rotating the valve stem unit 40 counterclockwise.

[0168] 1, 1z...Butterfly valve 10...Valve body 20...Valve seat 40, 40z...Valve stem unit 50, 50z...Valve body unit 42, 46...Transmission member 43...Support shaft 421, 421z...Transmission horizontal section 421a...Transmission contact surface 421b...Separation maintenance contact surface 422...Vertical connection section 423...Triangular projection 423z...Second triangular projection 425...Arch-shaped section 425z...Second arc-shaped section F...Flow path MD...Rotational movement conversion mechanism MR...Rotation restriction mechanism RD...Rotational reverse movement conversion mechanism

Claims

1. A valve comprising: a valve body having a tubular flow path; a valve stem rotatable about an axis relative to the valve body; a valve element that rotates with the rotation of the valve stem to open and close the flow path; and a valve seat provided between the valve body and the valve element for sealing, wherein the rotation from the open position to a predetermined angle is considered the first rotation, and the rotation of the valve stem from the predetermined angle to the closed position is considered the second rotation, and a rotation restricting mechanism that allows the first rotation of the valve element, restricts the rotation of the valve element accompanying the second rotation of the valve stem, and allows the movement of the valve element in a direction that brings it into close contact with the valve seat; and a rotational movement conversion mechanism that moves the valve element to bring it into close contact with the valve seat by the second rotation of the valve stem relative to the valve element whose rotation is restricted by the rotation restricting mechanism, wherein the rotational movement conversion mechanism is provided on at least one of the valve stem and the valve element. A butterfly valve having a cam portion that, by the second rotation of the valve stem, contacts the other of the valve stem and the valve body, and moves the valve body so that it is in close contact with the valve seat.

2. The butterfly valve according to claim 1, wherein the valve stem is provided with a transmission member having a rotation transmission portion for transmitting the first rotation of the valve stem to the valve body, and a support shaft is provided along the axis for rotatably supporting the transmission member on the side opposite to the valve stem relative to the valve body.

3. The butterfly valve according to claim 2, wherein the rotation transmission unit, the rotation restricting mechanism, and the rotation movement conversion mechanism are provided on both sides in the axial direction along the axis with respect to the valve body.

4. The butterfly valve according to claim 2, wherein the cam portion is provided on the transmission member, the transmission member is provided with a planar maintaining contact surface that contacts the valve body to maintain a tight seal of the valve body with respect to the valve seat, the rotation transmission portion has a planar transmission contact surface that contacts the valve body, and the transmission contact surface, the cam portion, and the maintaining contact surface are provided in this order from the front of rotation to the rear of rotation in the forward rotation direction from the first rotation to the second rotation.

5. The butterfly valve according to claim 2, wherein a portion of the transmission member is provided with an offset portion that is offset in a predetermined direction from the axis to suppress a reduction in the flow path area when the valve is open.

6. A butterfly valve according to any one of claims 2 to 5, wherein the rotation of the valve stem from the closed position to the predetermined angle is a second reverse rotation, and the rotation from the predetermined angle to the open position is a first reverse rotation, and the rotational movement conversion mechanism is provided to move the valve body, which has been moved by the rotational movement conversion mechanism to be in close contact with the valve seat, away from the valve seat by the second reverse rotation of the valve stem, and rotate the valve body to the first reverse rotation by the first reverse rotation of the valve stem, the rotational movement conversion mechanism is provided on at least one of the valve stem and the valve body, and has a second cam portion that, by the second reverse rotation of the valve stem relative to the valve body in close contact with the valve seat, abuts against the other of the valve stem and the valve body, thereby moving the valve body away from the valve seat.

7. The butterfly valve according to claim 6, wherein the rotational reverse movement conversion mechanism is provided on both sides in the axial direction along the axis of the valve body.

8. The butterfly valve according to claim 6, wherein the transmission member is provided with a reverse rotation transmission section for transmitting the reverse second rotation of the valve stem to the valve body, and a planar separation-maintaining contact surface that contacts the valve body to maintain the separation state of the valve body from the valve seat, the second cam section is provided on the transmission member, the reverse rotation transmission section has a planar second transmission contact surface that contacts the valve body, and the second transmission contact surface, the second cam section, and the separation-maintaining contact surface are provided in this order from the front of the reverse rotation to the rear of the reverse rotation in the reverse rotation direction from the reverse second rotation to the reverse first rotation.

9. The butterfly valve according to claim 8, wherein the rotational reverse movement conversion mechanism is provided on the opposite side of the axis from the rotational movement conversion mechanism.

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