JP6523734B2 - Butterfly valve - Google Patents

Description

  The present invention relates to a butterfly valve, and more particularly to an eccentric structure.

  As one of butterfly valves having an eccentric structure used under high temperature and high pressure conditions, such as steam lines of various thermal power generation and geothermal power generation facilities, a butterfly valve having a triple eccentric structure as shown in Patent Document 1, for example There is. In this butterfly valve, a pivot shaft for pivoting the valve body is eccentric from the valve element surface of the valve element in the fluid flow direction (primary eccentricity), and from the center of the valve element to one inner wall surface side of the flow path Eccentric (secondary eccentricity), and further, the contact surface of the valve box and the valve seat with the valve body is on a conical surface having a vertex at a position eccentric from the central axis of the flow path (third eccentricity) , Has three eccentric axes.

  Since the butterfly valve of this triple eccentric structure does not easily cause sliding between the valve box valve seat and the valve body valve seat when opening and closing the valve body, the valve body in the valve closing state can be opened smoothly. The service life of both valve seats can be extended.

Patent No. 3709196 gazette

  The butterfly valve of the triple eccentric structure shown in Patent Document 1 has a watertight seal by the valve body due to surface contact between the valve seat and the valve body, instead of hardly causing sliding between the valve seat and the valve body valve seat. Airtightness is ensured. That is, when a positional deviation or inclination occurs between the valve box valve seat and the valve body valve seat due to an error or the like on the assembly of the butterfly valve, a gap is generated between the two valve seats, and water tightness and airtightness are produced. There is a problem that can not be secured.

  Then, this invention makes it a subject to ensure a water-tight and airtight state reliably in the butterfly valve of eccentric structure.

  In order to solve the above-described problems, the present invention relates to a valve box in which a flow path is formed inside, a valve body provided so as to be able to open and close this flow path in the flow path of the valve box, and A pivot shaft for eccentrically moving from the center of the valve body to one of the inner wall side of the flow path from the center of the valve body to rotate the valve body, and the center of the flow path A virtual elliptical pyramid having an apex at a position eccentric to the axis and having a short axis along the direction of eccentricity from the center axis inclined with respect to the center axis is perpendicular to the center axis and separated by a predetermined distance When the virtual elliptical conical surface surrounded by both planes when cut by two flat surfaces is used as the contact surface, the valve box valve seat provided on the inner diameter side of the valve box and the outer periphery facing the valve box valve seat And a valve body valve seat having an end portion formed into a circular arc shape in cross section and abutting on the contact surface provided on the outer peripheral edge of the valve body. To constitute a fly valve.

  Alternatively, in the flow direction of the flow path from the valve body in which the flow path is formed inside, the valve body provided in the flow path of the valve box so as to freely open and close this flow path, and the valve body surface of the valve body It has an eccentricity, has an eccentricity on one inner wall side of the flow passage from the center of the valve body, and has a pivot shaft for rotating the valve body and a vertex at a position eccentric from the central axis of the flow passage. The virtual conical surface surrounded by both planes perpendicular to the central axis and separated by a predetermined distance from the virtual conical surface inclined with respect to the central axis as the abutting surface A valve box provided on the inner diameter side of the valve box, and an outer peripheral end facing the valve box valve seat having a circular arc shape in cross section, and a valve body abutting on the contact surface provided on the outer peripheral edge of the valve body It is also possible to constitute a butterfly valve provided with a valve seat.

  Thus, by forming the outer peripheral end of the valve body valve seat facing the valve box valve seat into a circular arc shape, the valve box valve seat and the valve body valve seat with the circular arc shaped cross section are in close contact with each other in line contact. And an airtight state is secured. Moreover, since the interference (pressing force) of both valve seats can be adjusted by the rotation of the rotation shaft, it is possible to always maintain the optimum water tightness and airtightness. When the valve body and the valve seat are made of an elastic material, the contact between the valve box and the valve body is further enhanced, which is more preferable. The term "valve body surface" as used herein includes a contact portion in which the valve box valve seat and the valve body valve seat abut each other when the valve body valve seat is closed, and a plane perpendicular to the central axis of the flow path Point to.

  In each configuration, at least one of the valve box valve seat and the valve body valve seat is moved relative to the valve box valve seat and the valve body valve seat in the plane of the valve body surface, It is preferable to further include an automatic aligning mechanism that adjusts the contact state between the valve box valve seat and the valve body valve seat.

  As a configuration provided with the self-aligning mechanism, the valve body valve seat is annular, and the self-centering mechanism is provided to the valve body in which the base of the inner peripheral edge of the valve body valve seat is fitted. A fitting recess and a gap formed at the bottom of the fitting recess can be provided.

  By providing the gap in this manner, when the valve seat is pressed by the valve box valve seat, the valve seat can be displaced into the gap. For this reason, the self-aligning function of the valve body valve seat with respect to the valve box valve seat is exhibited, and the contact force between the valve box valve seat and the valve body valve seat becomes even over the entire circumference of the valve body valve seat. And further improvement of airtightness can be expected.

  As a configuration provided with this self-aligning mechanism, the self-aligning mechanism is formed on a valve body fixing member for fixing the valve body valve seat to the valve body, and the valve body valve seat, and the valve body valve seat is A through-hole-like valve body displacement allowing portion that allows relative movement of the valve body fixing member in the plane of the valve body surface may be provided.

  By providing the valve body displacement permitting portion in this manner, when the valve body valve seat is pressed by the valve box valve seat, the self-aligning function of the valve body valve seat with respect to the valve box valve seat is exhibited, and the watertight and airtight state Further improvement can be expected.

  As a configuration provided with this self-aligning mechanism, the self-aligning mechanism is formed on a valve box fixing member for fixing the valve box valve seat to the valve box, and the valve box valve seat, and the valve box valve seat is A through hole-like valve box displacement allowing portion that allows relative movement of the valve box fixing member in the plane of the valve body surface may be provided.

  By providing the valve box displacement allowance portion in this way, when the valve box valve seat and the valve body valve seat abut, the self-aligning function of the valve box valve seat with respect to the valve body valve seat is exhibited, and the watertight and airtight state Further improvement can be expected.

  In each of the above embodiments, the outer peripheral end of the valve body valve seat is formed with an opening recess facing in the direction opposite to the eccentric direction of the pivot shaft eccentric from the valve body surface of the valve body. preferable.

  When pressure acts on the valve body in the eccentric direction of the rotating shaft which is eccentric from the valve body surface of this valve body, the pressure slightly moves the valve body in the valve opening direction by this pressure, and the butterfly valve of the eccentric structure is a valve box valve Since the seat and the valve seat are basically in surface contact, there is a risk that the water and air tightness may be reduced. Thus, by forming the opening recess in this manner, the water pressure acts on the opening recess and the valve body valve seat bulges radially outward, and the valve body slightly moves by this water pressure to form a gap between both valve seats. Even if it occurs, the bulging of the valve body valve seat closes the gap. For this reason, the water tightness and airtightness when the pressure acts in the above-mentioned eccentric direction are secured.

  In each of the above configurations, the valve disc includes a reinforcing plate disposed at a predetermined distance from the valve disc, and a rib plate connecting the valve disc and the reinforcing plate. It can also be a structure (hereinafter referred to as a multi-leaf valve).

  Thus, the pressure loss of the fluid can be reduced by using a multi-leaf valve body as the valve body.

  In this invention, in a butterfly valve having an eccentric structure, an outer diameter which is provided on the outer peripheral edge of the valve body and whose outer peripheral end facing the valve box valve seat has a circular arc shape in cross section is larger than the inner diameter of the valve box valve seat The structure provided with the valve body valve seat provided with the flexibility was adopted. By configuring in this manner, the valve box valve seat and the valve body valve seat having a circular arc shape in cross section are in close contact with each other in a line contact state, and a water tight and air tight state are secured. Moreover, since the interference (pressing force) of both valve seats can be adjusted by the rotation of the rotation shaft, it is possible to always maintain the optimum water tightness and airtightness.

Longitudinal sectional view showing a first embodiment of a butterfly valve according to the present invention Principal part longitudinal cross-sectional view of the butterfly valve shown in FIG. 1 It is a principal part longitudinal cross-sectional view of the butterfly valve shown in FIG. 1, Comprising: (a) is a 1st example, (b) is a 2nd example, (c) is a 3rd example Principal part longitudinal cross-sectional view which shows the effect | action of the butterfly valve shown in FIG. Longitudinal sectional view showing a state in which the butterfly valve shown in FIG. 1 is slightly opened It is a principal part longitudinal cross-sectional view which shows the state which water pressure acted on the butterfly valve shown in FIG. 1, Comprising: (a) is an eccentric side edge, (b) is an opposite edge Longitudinal sectional view showing a second embodiment of a butterfly valve according to the present invention Principal part longitudinal cross-sectional view of the butterfly valve shown in FIG. 7 The 3rd embodiment of the butterfly valve which concerns on this invention is shown, (a) is a longitudinal cross-sectional view, (b) is a cross-sectional view.

  A first embodiment of a butterfly valve according to the present invention will be described based on the drawings. The butterfly valve shown in FIG. 1 is provided on the outer periphery of the valve case 1, the valve body 2, the rotary shaft 3 of the valve body 2, the valve case 4 provided on the inner circumferential surface of the valve case 1, and the valve body 2. The valve body valve seat 5 is a quadruple eccentric structure having a main component.

  Inside the valve box 1 is formed a flow path for flowing liquid or gas. In the flow path, there is provided a valve body 2 which is pivoted around the rotation axis 3 to open and close the flow path. The rotary shaft 3 is eccentric in the fluid flow direction (right side in FIG. 1) from the mounting surface of the valve body 5 of the valve body 2 (primary eccentricity; see S1 in FIG. 1). It is decentered from the center of the flow path to one inner wall surface side (upper inner wall surface side in FIG. 1) of the flow path (secondary eccentricity; see symbol S2 in FIG. 1).

  The valve box 4 has an annular shape, and is attached to the inner diameter side of the valve box 1 by a valve box fixing member (bolt) 6. The inner peripheral surface (contact surface with the valve body valve seat 5) of the valve box valve seat 4 has a vertex at a position eccentric from the central axis of the flow path (third eccentricity, see S3 in FIG. 1). A virtual ellipsoidal conical surface f1 (quaternary eccentricity; see S4 in FIG. 1) having a short axis along the direction of eccentricity from the center axis inclined with respect to the center axis, perpendicular to the center axis and It consists of a virtual elliptical pyramid f1 surrounded by both planes when cut by two planes separated by a predetermined distance. More specifically, as shown in FIG. 2, on the eccentric side of the virtual ellipsoidal conical surface f1, the inner circumferential surface is a parallel surface 4a parallel to the central axis toward the vertex of the virtual ellipsoidal conical surface f1 (along the flow direction 3 (a) to (c), the inner circumferential surface on the opposite side of the eccentric side becomes an inclined surface 4b directed to the vertex of the virtual ellipsoidal conical surface f1. There is. The inclination angle of the inclined surface 4b is the largest on the opposite side, and gradually decreases toward the eccentric side.

  As shown in FIG. 2, the valve body valve seat 5 is a thin-walled annular member made of metal, and a base portion 5 a formed on the inner peripheral edge of the valve body valve seat 5 is an annular rim and the outer peripheral edge of the valve body 2. The holding member 8 is fitted into a fitting recess 7 formed between the holding member 8 and the holding member 8 and fixed by a valve body fixing member (bolt) 9 provided on the holding member 8. The outer peripheral end 5b of the valve body valve seat 5 facing the valve box valve seat 4 is a circular arc in cross section directed radially outward, and on the holding member 8 side of the outer peripheral end 5b, the holding member 8 side is The opening recessed part 5c which faces is formed. The outer peripheral end 5 b of the valve body 5 has an arc-like cross-section, and has a flexibility that causes a slight bending when an external force is applied, and the contact between the valve box 4 and the valve body 5. At the same time, the outer peripheral end 5 b is in close contact with the valve box 4 and the sufficient water tightness and airtightness are maintained. Further, even when water pressure acts on the outer peripheral end 5b of the valve body valve seat 5 from the holding member 8 side, the outer peripheral end 5b bulges outward in the radial direction by this water pressure, and the water tightness and airtightness are reliably maintained. Ru. The material of the valve body 5 is a material such as rubber or resin as long as it has sufficient strength and flexibility to ensure water tightness and airtightness and does not physically or chemically denatured by a fluid. Materials other than metal can also be adopted. As this valve body valve seat 5, as shown to FIG. 3 (a)-(c), the thing of various shapes is employable.

  Since the outer peripheral end 5b of the valve body valve seat 5 has a circular arc shape in cross section, the valve box valve seat 4 and the valve body valve seat 5 having a circular arc shape in cross section are substantially in line contact over the entire circumferential direction. Get close For this reason, compared with the case where both valve seats 4 and 5 are in surface contact, high contact pressure can be secured even with a smaller contact force, and high water tightness and airtightness can be secured. In addition, even if the valve body valve seat 5 rotates and the angle thereof changes a little, it is easy to maintain the contact state with the valve box valve seat 4 over the entire circumferential direction of the valve body valve seat 5 It has become.

  A gap 10 of a predetermined depth is formed continuously with the fitting recess 7 at the bottom of the fitting recess 7 into which the valve body valve seat 5 is fitted. Automatic adjustment is performed by the fitting recess 7 and the gap 10 Heart mechanism is configured. The self-alignment mechanism moves the valve body valve seat 5 relative to the valve box valve seat 4 in the plane of the valve body surface, so that the abutment between the valve box valve seat 4 and the valve body valve seat 5 The condition can be adjusted.

  When the valve body 2 is closed in a state where the central axis of the valve box 1 and the central axis of the valve body 2 completely coincide with each other, the valve body 2 and the valve body valve seat 5 are completely concentrically located. The depth of the gap 10 (the distance from the bottom of the base 5 a of the valve seat 5 to the bottom of the gap 10) is uniform over the entire circumferential direction of the valve 2. On the other hand, when a positional deviation or inclination occurs between the valve box valve seat 4 and the valve body valve seat 5 due to an error or the like in the assembly of the butterfly valve, as shown in FIG. By the relative movement of the body valve seat 5, a part of the valve body valve seat 5 is shifted into the gap 10. In addition, when a part of the valve body valve seat 5 is shifted into the gap portion 10, the valve body valve seat 5 slightly protrudes from the fitting recess 7 at the position opposite to the center of the valve body valve seat 5. It will be in a state of

  Thus, part of the valve body valve seat 5 is displaced into the gap 10 and slightly protrudes from the fitting recess 7 at the opposite position, whereby the space between the valve body 2 and the valve body valve seat 5 is Self-alignment is performed to shift the axial center and to make the axial center between the valve box valve seat 4 and the valve body valve seat 5 coincide. By this automatic alignment, the gap between the valve box valve seat 4 and the valve body valve seat 5 is eliminated, and high water tightness and airtightness are secured. The depth of the gap 10 may be changed as appropriate in consideration of the inner diameter of the valve box 4 and the outer diameter of the valve seat 5.

  A seal member 11 is interposed between the valve body 2 and the valve body valve seat 5, and the seal member 11 passes through a gap between the valve body 2 and the valve body valve seat 5. It is preventing the back leak that water leaks.

  As shown in FIG. 5, when the rotary shaft 3 is rotated in the direction of the arrow, the valve box 2 and the valve body 5 are separated and the valve 2 opens. As described above, the valve box valve seat 4 and the valve body valve seat 5 of the butterfly valve of the quadruple eccentric structure according to the present invention are substantially in line contact with each other and hardly slide when the valve is opened. Therefore, the valve body 2 in the valve closed state can be opened smoothly, and the service life of both the valve seats 4 and 5 can be prolonged.

  In the butterfly valve of the eccentric structure, it is assumed that the fluid flowing through the flow path in the valve box 1 flows in one direction (in the present embodiment, from the right to the left in the butterfly valve described in FIG. 1). There is something designed. However, due to the connection configuration of the pipeline, the flow rate of the fluid, etc., the fluid flows in the direction opposite to the designed flow direction, as shown by white arrows in FIGS. 6 (a) and 6 (b). Water pressure acts on the valve body 2 when the valve body 2 is in a closed state (in the butterfly valve shown in FIG. 1, rightward pressure acts on the left side surface of the valve body 2) is there. Thus, when the water pressure acts on the valve body 2, the valve body 2 is slightly displaced in the action direction of the water pressure by the water pressure, and particularly on the side where the inclined surface 4 b is formed on the valve seat 4 There may be a gap between the valve seat 4 and the valve body valve seat 5.

  Thus, when the valve body 2 is displaced by water pressure, the flow path downstream side formed in the outer peripheral end 5 b of the valve body valve seat 5 (that is, the eccentric direction of the pivot shaft 3 eccentric from the valve body surface of the valve body 2) When the water pressure acts on the opening concave portion 5c facing the reverse direction, the valve body valve seat 5 (the outer peripheral end 5b) expands radially outward. By this swelling, the gap between the valve box valve seat 4 and the valve body valve seat 5 is completely closed, and the water tightness and airtightness at the time of water pressure operation are secured.

  When water pressure acts on the valve body 2, the rotary shaft 3 is rotated to further close the valve body 2, thereby allowing the valve box valve seat 4 and the valve body valve seat 5 to more reliably abut. It can also be When the axial center between the valve box valve seat 4 and the valve body valve seat 5 deviates at the time of this additional closing, as described above, the valve body valve seat 5 moves relative to the valve body 2 The center of the shaft between the valve body 2 and the valve body 5 is offset so that the axes of the valve box 4 and the valve body 5 are aligned. By this automatic alignment, it is possible to further improve the water tightness and the air tightness together with the action of the outer peripheral end 5b of the valve body valve seat 5 expanding radially outward.

  In addition, the valve box valve seat 4 used for the butterfly valve of a quadruple eccentric structure can be processed by using a 5-axis machining center or the like. Moreover, since the valve body valve seat 5 and the holding member 8 have a simple ring shape, the processing method can be easily processed without being particularly limited.

  Although the four-fold eccentricity butterfly valve has been described above, the pivot shaft 3 for pivoting the valve body 2 is eccentric in the fluid flow direction from the mounting surface of the valve body valve seat 5 of the valve body 2 (Primary eccentricity; see code S1 in FIG. 1), eccentric to one inner wall side of the flow path from the center of the valve body 2 (secondary eccentricity; see code S2 in FIG. 1) The inner peripheral surface (the contact surface with the valve body valve seat 5) has an apex at a position eccentric from the central axis of the flow path (third eccentricity; see S3 in FIG. 1), and further, the center A triple eccentricity with the virtual conical surface f2 surrounded by both planes as the contact surface when the virtual conical surface f2 inclined with respect to the axis is cut by two planes perpendicular to the central axis and separated by a predetermined distance The invention can also be applied to a butterfly valve of the structure (see FIG. 1). The butterfly valve of the triple eccentric structure according to the present invention has a contact relation between the valve box valve seat 4 and the valve body valve seat 5, a self-aligning function of the valve body valve seat 5, and securing of water tightness and airtightness under water pressure action. The configuration of the invention is common to that of the quadruple eccentric structure butterfly valve, and like the butterfly valve of the quadruple eccentric structure, it is possible to solve the problem of the present invention that the water tightness and airtightness are assuredly ensured.

  In the butterfly valve having the triple eccentricity structure, the imaginary conical surface f2 inclined with respect to the central axis of the flow passage and the inner periphery of the valve box 1 intersect in an elliptical shape in the plane with respect to the flow passage Because of this, the cross section perpendicular to the flow path of the valve box valve seat 4, the valve body 2, and the valve body valve seat 5 is elliptical. For these processes, it is advantageous to use a 5-axis machining center or the like, as in the case of a four-fold eccentricity butterfly valve.

  7 and 8 show a second embodiment of the butterfly valve according to the present invention. The basic configuration of the butterfly valve according to the second embodiment is the same as the butterfly valve according to the first embodiment, but the configuration of the self-aligning mechanism is different.

  In the self-aligning mechanism of this embodiment, the valve body valve seat 5 has a disc shape, and the valve body valve seat 5 is fixed to the valve body 2 by the valve body fixing member 9 via the holding member 8 It is done. A through hole (valve body displacement allowing portion) 14 for passing the valve body fixing member 9 is formed in the valve body valve seat 5, and the inner diameter of the through hole 14 is slightly smaller than the diameter of the valve body fixing member 9. It is larger (see Figure 8). In this case, the valve body 5 is moved relative to the valve body fixing member 9 within the plane of the valve body surface by the difference between the inner diameter of the through hole 14 and the diameter of the valve body fixing member 9. As a result, the aligning action of the valve body 5 is exerted.

  A counterbore 15 is formed on the surface of the holding member 8 facing the valve body valve seat 5. Thus, by forming the countersink 15, sliding friction between the holding member 8 and the valve body valve seat 5 can be reduced, and automatic alignment of the valve body valve seat 5 can be performed more smoothly. it can.

  Furthermore, in the self-aligning mechanism of this embodiment, the valve box valve seat 4 is fixed to the valve box 1 by a valve box fixing member (bolt) 6. A through hole (valve box displacement allowing portion) 16 for passing the valve box fixing member 6 is formed in the valve box valve seat 4, and the inner diameter of the through hole 16 is slightly smaller than the diameter of the valve box fixing member 6. It is larger (see Figure 8). With this configuration, the valve box 4 is moved relative to the valve box fixing member 6 within the plane of the valve body by the difference between the inner diameter of the through hole 16 and the diameter of the valve box fixing member 6. As a result, the aligning action of the valve box 4 is exhibited.

  Thus, by providing the self-aligning mechanism, it is possible to further improve the water tightness and airtightness. In this embodiment, a configuration is shown in which both of the self-aligning mechanism on the valve body valve seat 5 side and the self-aligning mechanism on the valve box valve seat 4 side are provided. It is good also as composition provided.

  A third embodiment of the butterfly valve according to the present invention is shown in FIGS. 9 (a) and 9 (b). The basic configuration of the butterfly valve according to the third embodiment is the same as that of the butterfly valve according to the first embodiment, but when the valve body 2 is fully opened with a predetermined interval between the valve body 2 and the valve body 2 The difference is that a reinforcing plate 12 disposed in parallel in a direction along the flow path and a rib plate 13 connecting the valve body 2 and the reinforcing plate 12 are provided to form a multi-leaf valve body. Thus, when the valve body 2 is a multi-leaf valve body, pressure loss can be reduced when the valve body 2 is opened. The bileaflet valve body can be applied to either a triple eccentric or quadruple eccentric butterfly valve.

  The butterfly valve described in each of the above-described embodiments is merely an example, and in the butterfly valve of the eccentric structure, the shapes of the respective members as long as they can solve the problem of the present invention of ensuring watertightness and airtightness reliably. The material can be changed as appropriate. For example, in the above-mentioned embodiment, although valve box valve seat 4 is attached to valve box 1 with valve box fixed member 6, valve box 1 and valve box valve seat 4 can also be constituted in one. Further, in the above embodiment, the eccentric side of the inner peripheral surface of the valve box valve seat 4 is the parallel surface 4a parallel to the central axis of the flow path, but this configuration is merely an example, and Other configurations may be employed, such as an inclined surface that is inclined.

DESCRIPTION OF SYMBOLS 1 valve box 2 valve body 3 rotation shaft 4 valve box valve seat 4a parallel surface 4b inclined surface 5 valve body valve seat 5a base 5b outer peripheral end 5c opening recessed portion 6 valve box fixing member 7 fitting recessed portion 8 holding member 9 valve body Fixing member 10 Gap 11 Sealing member 12 Reinforcing plate 13 Rib plate 14 Through hole (valve body displacement allowing portion)
15 countersink 16 through hole (valve box displacement allowance part)
f1 virtual elliptic cone f2 virtual cone

Claims (2)

A valve box (1) having a flow passage formed therein,
A valve body (2) provided so as to be able to open and close the flow path in the flow path of the valve box (1);
The valve body (2) is eccentric in the flow direction of the flow path from the valve body surface of the valve body (2), and is eccentric from the center of the valve body (2) to one inner wall surface side of the flow path. A rotating shaft (3) to be rotated;
From the center axis on the central axis which has a vertex at a position eccentric in the same direction as the eccentric direction to the inner wall side of the rotation axis (3) from on the central axis of the flow path A virtual elliptical pyramid (f1) having a short axis along the direction of eccentricity of the second circle, the virtual elliptical pyramid (f1) being surrounded by the two planes perpendicular to the central axis and separated by a predetermined distance A valve box valve seat (4) provided on the inner diameter side of the valve box (1).
A valve body valve seat (5) having an outer peripheral end (5b) facing the valve box valve seat (4) formed into an arc shape in cross section and abutting on the contact surface provided on the outer peripheral edge of the valve body (2);
Equipped with
An opening concave portion (5c) facing the outer peripheral end (5b) of the valve body valve seat (5) in the direction opposite to the eccentric direction of the pivot shaft (3) eccentric from the valve body surface of the valve body (2) Formed a butterfly valve. A valve box (1) having a flow passage formed therein,
A valve body (2) provided so as to be able to open and close the flow path in the flow path of the valve box (1);
The valve body (2) is eccentric in the flow direction of the flow path from the valve body surface of the valve body (2), and is eccentric from the center of the valve body (2) to one inner wall surface side of the flow path. A rotating shaft (3) to be rotated;
A virtual conical surface (f2) having a vertex at a position eccentric in the same direction as the eccentric direction toward the inner wall side of the rotation shaft (3) from on the central axis of the flow path and inclined with respect to the central axis ) Is cut by two planes perpendicular to the central axis and separated by a predetermined distance, and the virtual conical surface (f2) surrounded by both planes is the contact surface, and the inner diameter side of the valve box (1) Valve box valve seat (4) provided in the
A valve body valve seat (5) having an outer peripheral end (5b) facing the valve box valve seat (4) formed into an arc shape in cross section and abutting on the contact surface provided on the outer peripheral edge of the valve body (2);
Equipped with
An opening concave portion (5c) facing the outer peripheral end (5b) of the valve body valve seat (5) in the direction opposite to the eccentric direction of the pivot shaft (3) eccentric from the valve body surface of the valve body (2) Formed a butterfly valve.

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