non-return valve

Abstract

The check valve (1) includes a moving body (30), a valve box (10), a valve sleeve (14), a primary flow path (40), and a secondary flow path (50). The moving body (30) is a member that can move linearly back and forth between a closed state in which it is in close contact with a valve seat (12) and an open state in which it is spaced apart from the valve seat (12). The valve box (10) is a member that includes a valve sleeve (14). The valve seat (12) is fixed to the valve box (10). The valve sleeve (14) is a member that extends in the movement direction of the moving body (30) and is the member within which the moving body (30) moves. The primary flow path (40) is located upstream of the valve sleeve (14) and has its axis in the direction of the linear main axis. The secondary flow path (50) is located downstream of the valve sleeve (14) and has its axis in the direction of the main axis. The flow direction of the first main flow of the fluid passing through the inside of the valve cylinder (14) from the upstream side to the downstream side has a larger component in the moving direction of the moving body (30) than in the main axis direction.

Description

[Technical Field]

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

[0002] 2. Description of the Related Art A check valve for allowing a fluid in a pipe to pass in one direction is known. Regarding this type of technology, Patent Document 1 below discloses a straight pipe joint type check valve in which an upstream primary flow path (inlet flow path) and a downstream secondary flow path (outlet flow path) are arranged coaxially. This check valve is known as an oblique lift type in which the valve disc moves obliquely with respect to the main axial direction of the primary flow path and the secondary flow path. More specifically, the check valve in Patent Document 1 includes a valve box (12) having a valve seat (15), a housing (23) that can be seated on the valve seat (15), and a coil spring (18) that exerts a biasing force in a direction that presses down the valve disc (16). The fluid pushes up against the valve element 16 and flows from the primary flow path to the secondary flow path. While the fluid is flowing from the primary flow path to the secondary flow path, the valve element is kept in an upwardly pushed-up state by the flow of the fluid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 1,703,248 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the primary flow path is connected to the secondary flow path while the valve disc is pushed upward, the fluid tends to move from the primary flow path to the secondary flow path along the main axis. Therefore, the valve disc that is pushed upward is positioned away from the flow path through which the fluid moves, and is therefore less susceptible to the water pressure of the fluid. As a result, it may be difficult to maintain the valve disc in this state after it has been pushed upward.

[0005] The present invention has been made in view of the above-mentioned problems, and provides a check valve in which the state in which the valve body is pushed upward is easily maintained. [Means for solving the problem]

[0006] The check valve of the present invention is a straight pipe joint type oblique lift check valve in which a fluid flows from the upstream side to the downstream side, and comprises a valve seat, a movable body that can move linearly back and forth between a closed state in which it is in close contact with the valve seat and an open state in which it is spaced apart from the valve seat, a valve box to which the valve seat is fixed that includes a valve cylinder that extends in the moving direction of the movable body and inside which the movable body moves, and a valve cylinder that is located upstream of the valve cylinder and has a linear main axis. The axis is a primary flow path; and a main shaft located downstream of the valve cylinder. The axis is a secondary flow path; The movable body includes a valve disc supported by the valve seat in the closed state and a valve stem extending from the valve disc in both directions of the movement direction, and in a vertical direction from a top side of the valve box where the valve cylinder is provided to a bottom side opposite the top side, based on a main axis direction in which the main axis extends, a part of the bottom side of the valve seat is located closer to the bottom side than the main axis, and the interior of the valve cylinder includes an internal region located closer to the bottom side in the movement direction than the valve disc in the open state and downstream of the valve stem in the main axis direction, when a valve opening degree representing the position of the valve disc in the vertical direction is 30% or more, From the upstream side to the downstream side of the valve cylinder the inner region The flow direction of the first main flow of the fluid passing through the moving body has a larger component in the direction of the movement of the moving body than in the direction of the main axis.

[0007] The flow direction of the first main flow, which is the main flow of the fluid passing through the inside of the valve cylinder, has more components in the direction of movement of the moving body than in the direction of the main axis, so the first main flow mainly flows in a direction pushing up the valve body in the direction of movement (especially towards the ceiling in the direction of movement). [Effects of the Invention]

[0008] According to the check valve of the present invention, the first main flow mainly flows in the direction of movement, pushing up the valve element, so that the fluid continues to collide against the valve element in the direction of pushing up the valve element. This makes it easier to maintain the valve body in an upwardly pushed state. [Brief explanation of the drawings]

[0009] The above-mentioned objects, as well as other objects, features and advantages, will become more apparent from the preferred embodiments described below and the accompanying drawings.

[0010] [Figure 1] 1 is a perspective view showing an example of a check valve according to a first embodiment of the present invention. FIG. [Figure 2] 1 is a longitudinal cross-sectional view taken along a main axis direction of a check valve in a closed state according to a first embodiment. FIG. [Figure 3] 1 is a longitudinal cross-sectional view taken along a main axis direction of a check valve in an open state according to a first embodiment. FIG. [Figure 4] Fig. 4(a) is a velocity distribution diagram when a fluid flows through the check valve according to the first embodiment, and Fig. 4(b) is a diagram showing regions A to D in the same diagram as Fig. 4(a). [Figure 5] 5(a) and 5(b) are velocity distribution diagrams when a fluid flows through the check valve according to the first embodiment. [Figure 6] 1 is a rear view of a valve body in a check valve according to a first embodiment, in which the outline of a valve stem is shown by a dotted line. [Figure 7] Fig. 7(a) is a rear view of the lower cylindrical end portion according to the first embodiment, and Fig. 7(b) is a rear view of the lower end portion of the valve stem according to the first embodiment. [Figure 8] Fig. 8(a) is a partially exploded rear view of the valve body according to the first embodiment, and Fig. 8(b) is a longitudinal cross-sectional view of the valve body and valve stem. [Figure 9] FIG. 4 is a perspective view of a check valve according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a longitudinal cross-sectional view taken along the main axis direction of a check valve in a closed state according to a second embodiment. [Figure 11] FIG. 10 is a longitudinal cross-sectional view taken along the main axis direction of a check valve in an open state according to a second embodiment. [Figure 12] FIG. 10 is a velocity distribution diagram when a fluid flows through a check valve according to a second embodiment. [Figure 13] 13(a) and 13(b) are velocity distribution diagrams when a fluid flows through the check valve according to the second embodiment. [Figure 14] 10 is a rear view of the valve body of the check valve according to the second embodiment, in which the outline of the valve stem is shown by a dotted line. DETAILED DESCRIPTION OF THE INVENTION

[0011] The various components of the check valve of the present invention do not need to be independent entities, and it is acceptable for multiple components to be formed as a single member, for one component to be formed from multiple members, for one component to be part of another component, or for part of one component to overlap with part of another component, etc.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, corresponding components are designated by common reference numerals, and duplicated descriptions will be omitted as appropriate. In this embodiment, the front-rear, left-right, top-bottom directions are defined as shown in the drawings. In this embodiment, the front-rear direction corresponds to the main axis direction, which will be described later. The left-right direction may also be referred to as the width direction of the check valve 1. However, this definition is given for the sake of convenience in order to easily explain the relative relationships between the components, and does not limit the directions during manufacture or use of the product embodying the present invention. The up-down direction is not limited to the vertical direction, but refers to a direction perpendicular to the main axis direction and the width direction. For example, when the check valve 1 is placed on a horizontal surface and attached to a pipe, the up-down direction is vertical. However, when the check valve 1 is attached to a surface inclined relative to the horizontal plane or to an upright surface perpendicular to the horizontal plane, the up-down direction is not vertical. Furthermore, the term "flat surface" as used in the present invention means a shape that is physically formed with a flat surface as a target, and it is not necessarily required that the surface be a geometrically perfect flat surface.

[0013] First Embodiment (non-return valve) Fig. 1 is a perspective view showing an example of a check valve 1 according to a first embodiment of the present invention, and Fig. 2 is a longitudinal sectional view of the check valve 1.

[0014] First, an overview of the check valve 1 of this embodiment will be described. As shown in FIG. 2, the check valve 1 is a straight pipe joint type oblique lift check valve through which a fluid 200 (see FIG. 4) flows from the upstream side to the downstream side. The check valve 1 includes a valve seat 12, a moving body 30, a valve body 10, a primary flow path 40, and a secondary flow path 50. The movable body 30 is a member that can move back and forth linearly between a closed state in which it is in close contact with the valve seat 12 and an open state in which it is separated from the valve seat 12. The valve box 10 is a member that includes a valve cylinder 14. The valve seat 12 is fixed to the valve box 10. The valve cylinder 14 is a member that extends in the direction of movement of the movable body 30, and is a member within which the movable body 30 moves. The primary flow path 40 is located upstream of the valve cylinder 14, and has an axis in the direction of the linear main axis (the direction indicated by the dashed line I in FIG. 2). The secondary flow path 50 is located downstream of the valve cylinder 14, and has an axis in the direction of the main axis. As shown in Figures 4(a) and 4(b), the flow direction of the first main flow of the fluid 200 passing through the inside of the valve cylinder 14 from the upstream side to the downstream side (the main flow of the fluid 200 shown in region A or region B in Figure 4(b)) has more components in the movement direction of the moving body 30 than in the main axis direction. By combining the shapes and arrangements of the various elements that make up the check valve 1, it is possible to realize a first main flow in which the component in the movement direction of the moving body 30 is more than in the main axis direction. How this is achieved will be described in detail below. The flow direction of the first main flow, which is the main flow of the fluid 200 passing through the inside of the valve cylinder 14, has more components in the movement direction of the moving body 30 than in the main axis direction, so that the first main flow mainly flows in a direction pushing up the moving body 30 (the valve element 32 described below) in the movement direction (particularly toward the ceiling in the movement direction). Because the first main flow mainly flows in a direction pushing up the valve element 32 in the movement direction, the fluid 200 continues to collide with the valve element 32 in a direction pushing up the valve element 32. This makes it easier to maintain the state in which the valve element 32 is pushed up.

[0015] Next, the check valve 1 of this embodiment will be described in detail. The check valve 1 is a component installed midway in a pipe that allows fluid to pass in one direction from upstream to downstream, and is a component for preventing the fluid from flowing back from downstream to upstream. As described above, the check valve 1 of this embodiment is a straight pipe fitting type, oblique lift type. The straight pipe fitting type check valve 1 is a check valve in which the pipe connected to the downstream side of the check valve 1 (downstream pipe) extends as an extension of the pipe connected to the upstream side of the check valve 1 (upstream pipe). That is, in a straight pipe fitting type check valve, the outflow direction is an extension of the inflow direction. In this embodiment, the check valve 1 connects the upstream pipe and the downstream pipe so that they are arranged coaxially. The oblique lift type check valve 1 is a check valve in which the valve element moves in a direction oblique to the main axis, which will be described later. The closed state of the check valve 1 is a state in which the movement of the fluid from upstream to downstream of the check valve 1 is restricted by a movable body 30, which will be described later, as shown in FIG. 2 . In the closed state, the movement of the fluid 200 does not need to be completely prevented; it is sufficient that the movement of the fluid 200 is sufficiently restricted according to the purpose. In the closed state of this embodiment, the movable body 30 is seated on the valve seat 12, as will be described later, thereby narrowing the flow path of the fluid 200 by the movable body 30 and restricting the movement of the fluid 200. The open state of the check valve 1 is a state in which the movement of the fluid 200 is less restricted than in the closed state of the check valve 1, as shown in FIG. 3 . Specifically, in the open state of the check valve 1, the valve seat 12 is separated from the movable body 30, and a gap is generated between the valve seat 12 and the movable body 30. The fluid 200 can move from upstream to downstream through this gap. In the open state, the movable body 30 may be pushed up to the highest position, or may be located midway along the valve shaft 34. That is, in the open state of the check valve 1, the movement of the fluid 200 from upstream to downstream may be slightly restricted. However, the restriction on the movement of the fluid 200 in the open state of the check valve 1 is smaller than the restriction on the movement of the fluid 200 in the closed state of the check valve 1.

[0016] FIG. 2 is a vertical cross-sectional view of the check valve 1. The valve box 10 is a housing through which a fluid flows. The valve box 10 houses a moving body 30. The housing is composed of a wall portion 19. Here, the wall portion 19 includes a piping wall portion 19a, a valve cylinder wall portion 19b, and a ceiling portion 15, which will be described later. In this embodiment, the valve box 10 includes a piping section 11 and a valve cylinder 14. The piping section 11 is a section through which the fluid 200 mainly flows from upstream to downstream. That is, the piping section 11 connects the inlet path (primary flow path 40) of the fluid to the outlet path (secondary flow path 50). More specifically, the piping section 11 extends in a direction connecting the center of the inlet 11a and the center of the outlet 11b of the check valve 1 (the left-right direction in FIG. 2, indicated by the dashed-dotted line). Here, the axis connecting the center of the inlet 11a and the center of the outlet 11b (the axis indicated by the dashed-dotted line in FIG. 2) is referred to as the main axis, and the extension direction of the main axis is referred to as the main axis direction. The piping section 11 is formed by a wall section 19 (piping wall section 19a) arranged to surround the periphery of the main axis, with the main axis as its axis center. At both ends of the pipe portion 11 in the main axis direction, flange portions 17 are provided that protrude in a direction perpendicular to the main axis direction. The valve cylinder 14 is a part of the valve box 10 that houses the moving body 30. The valve cylinder 14 extends in the direction of movement of the moving body 30 (the diagonal direction connecting the upper left and lower right in FIG. 2). The valve cylinder 14 is formed by a wall portion 19 (valve cylinder wall portion 19b) that is arranged to cover the axis centered on the direction of movement of the moving body 30. More specifically, the valve cylinder 14 is formed by the valve cylinder wall portion 19b that is arranged to cover the periphery of the valve axis. At the upper end of the valve cylinder 14, the space inside the valve cylinder 14 is closed by a ceiling portion 15. The upper end of the valve cylinder 14 is one end of the valve cylinder 14 that is on the upper side in the direction of movement. Note that the upper side here refers to the side of the valve box 10 on which the valve cylinder is provided, relative to the main axis. The upper side is also called the top side. At the lower end of the valve cylinder 14, the internal space of the valve cylinder 14 communicates with the internal space of the piping section 11. The lower end of the valve cylinder 14 is one end of the valve cylinder 14 on the lower side in the direction of movement. The lower side is also called the bottom side. In this embodiment, the ceiling portion 15 also serves as a lid for the valve cylinder 14. That is, the internal space of the valve cylinder 14 can be connected to the outside by opening the ceiling portion 15. The ceiling portion 15 is fixed to the valve cylinder wall portion 19b with fasteners 15b to prevent it from opening.

[0017] The valve seat 12 is a part of the check valve 1 that is fixed to the valve box 10, and is a part that comes into contact with the movable body 30 when the check valve 1 is in a closed state. In this embodiment, the valve seat 12 is a protruding part that protrudes from the wall 19 (the piping wall 19a or the valve cylinder wall 19b) toward the inside of the valve box 10. More specifically, the valve seat 12 protrudes from the wall 19 toward the radially inward direction of the valve cylinder 14. The radial direction of the valve cylinder 14 refers to the direction that extends radially from a valve stem 34 (described later) toward the periphery of the valve cylinder 14 (the valve cylinder wall 19b) when viewed from the direction of movement of the movable body 30. The radially inward direction of the valve cylinder 14 refers to the direction that extends from the periphery of the valve cylinder 14 (the valve cylinder wall 19b) toward the valve stem 34 when viewed from the direction of movement of the movable body 30. The valve seat 12 may be a member separate from the valve box 10 (wall portion 19 ) and fixed to the valve box 10 by adhesive, welding, or other methods, or may be formed integrally with the valve box 10 . The valve seat 12 in this embodiment extends around the valve stem 34. In other words, the valve seat 12 extends in the circumferential direction of the piping section 11 and is arranged all the way around in that circumferential direction. As a result, the valve seat 12 can come into contact with the entire periphery of a moving body (particularly the sealing section 36) described below. The valve seat 12 in this embodiment has a surface facing upward in the direction of movement of the moving body 30. The moving body 30 can come into surface contact with this surface.

[0018] The movable body 30 is a member that is movable in a predetermined direction of movement. When the movable body 30 moves downward in the direction of movement, it can come into contact with the valve seat 12, and when it moves upward in the direction of movement, it can move away from the valve seat 12. The moving body 30 has a diameter sufficient to restrict the flow of the fluid 200 from upstream to downstream. In this embodiment, the diameter of the moving body 30 (the maximum diameter of the moving body 30 when viewed from the direction of movement of the moving body 30) is larger than the inner diameter of the valve seat 12 (the maximum diameter when viewed from the direction of movement of the moving body 30). This allows the moving body 30 to come into contact with the valve seat 12 over the entire periphery of the valve seat 12 when the check valve 1 is in the closed state, thereby allowing the moving body 30 to sufficiently restrict the movement of the fluid 200. Alternatively, the diameter of the moving body 30 may be the same as or smaller than the inner diameter of the valve seat 12.

[0019] As shown in FIG. 2, in this embodiment, the moving body 30 includes a valve body 32 and a valve stem 34 . The valve element 32 is a member that is supported by the valve seat 12 when the check valve 1 is in the closed state. The valve element 32 being supported by the valve seat 12 refers to a state in which the valve element 32 is placed on the valve seat 12 and at least a portion of the weight of the valve element 32 is applied to the valve seat 12. When the valve element 32 moves in the moving direction of the movable body 30, the check valve 1 transitions from the closed state to the open state, or from the open state to the closed state. The valve stem 34 is a member that assists the movement of the valve element 32. Specifically, in this embodiment, the valve element 32 is fixed to the valve stem 34, and as will be described later, at least one end of the valve stem 34 is inserted into the cylindrical portion 16. Therefore, the valve element 32 can move in a predetermined movement direction by moving or sliding the valve stem 34 along the cylindrical portion 16. Alternatively to this embodiment, the valve element 32 may not be fixed to the valve stem 34, and the valve element 32 may slide on the valve stem 34, thereby assisting the movement of the valve element 32. In this embodiment, the valve stem 34 is a member extending from the valve element 32 in both directions of movement. The term "extending from the valve element 32 in both directions of movement" means that the valve stem 34 extends from the valve element 32 in both directions of movement in at least one of the following states: the closed state, the open state, or a state in transition from the closed state to the open state of the check valve 1. In this embodiment, the valve element 32 is fixed to the valve stem 34, and the relative positions of the valve element 32 and the valve stem 34 are fixed. The valve element 32 is disposed midway along the length of the valve stem 34. That is, the valve stem 34 extends from the valve element 32 in both directions of movement in any of the states of the check valve 1: the closed state, the open state, or a state in transition from the closed state to the open state. Alternatively, if the valve stem 34 is not fixed to the valve element 32, it is sufficient that the valve stem 34 extends from the valve element 32 in both directions of movement at least in a state in which the check valve 1 transitions from the closed state to the open state. When the check valve 1 is in the closed or open state, the valve stem 34 may extend from the valve element 32 in both directions in the movement direction, or may extend from the valve element 32 in only one direction in the movement direction. In this embodiment, the valve shaft 34 is an axial member disposed at the center of the valve cylinder 14 in the movement direction of the moving body 30 (valve element 32) and is a member that penetrates the valve element 32, but is not limited to this. The valve shaft 34 may also be a cylindrical member disposed radially outward of the valve element 32 from the valve cylinder 14. The valve element 32 may move or slide inside the valve shaft 34 along the valve shaft 34.

[0020] In this embodiment, as described above, the valve element 32 is fixed to the valve stem 34. Specifically, as shown in FIG. 8(b), the valve element 32 is fixed to the valve stem 34 by the engagement screw 35. The valve stem 34 has a screw receiving portion 34d, which is a protrusion that protrudes from the circumferential surface of the valve stem 34. A part of the valve element 32 (a first gripping portion 38 and a second gripping portion 39, which will be described later) is disposed between the engagement screw 35 and the screw receiving portion 34d. The engagement screw 35 is threadedly engaged with a thread groove provided on the circumferential surface of the valve stem 34 and comes close to the screw receiving portion 34d, so that the screw receiving portion 34d and the engagement screw 35 can grip the valve element 32.

[0021] 2, the ceiling portion 15 includes a ceiling cavity 15a that can accommodate a portion (upper end portion 34b) of the valve stem 34. In this embodiment, a portion of the ceiling portion 15 protrudes upward in the movement direction of the movable body 30, and the interior of this portion is hollow. Since the upper end portion 34b can be accommodated in the ceiling cavity 15a, the valve stem 34 can be positioned sufficiently high in the moving direction of the moving body 30 in the open state.

[0022] In this embodiment, both ends (the upper end 34b and the lower end 34a) of the valve stem 34 are supported by the wall 19 of the valve box 10. In this embodiment, the upper end 34b of the valve stem 34 is supported by the ceiling 15, and the lower end 34a of the valve stem 34 is supported by the pipe wall 19a or the valve cylinder wall 19b. "Both ends of the valve stem 34 are supported by the wall 19 of the valve box 10" means that both ends of the valve stem 34 are in contact with the valve box 10 or a member fixed to the valve box 10, and at least a portion of the weight of the valve stem 34 is applied to the valve box 10 at each of the both ends. The valve stem 34 may be in contact with the wall 19 of the valve box 10, so that the weight of the valve stem 34 is applied directly to the wall 19, or the valve stem 34 may be in contact with another member fixed to the wall 19 of the valve box 10, so that the weight of the valve stem 34 is applied indirectly to the wall 19 via the other member. In this embodiment, part of the weight of the valve stem 34 is also supported by a spring body 37, which will be described later. Specifically, the valve stem 34 is disposed between the valve disc 32 and the upper cylindrical end portion 16b, which is fixed to the ceiling portion 15. As will be described later, the spring body 37 biases the ceiling portion 15 and the valve disc 32 in the direction of movement of the movable body 30. Because the spring body 37 biases the ceiling portion 15 and the valve disc 32, the valve stem 34, which spans the upper cylindrical end portion 16b and the valve disc 32, is held in an orientation that is aligned with the direction of movement of the movable body 30. Specifically, the lower end 34a (the end of the valve shaft 34 facing the bottom surface of the check valve 1) and the upper end 34b (the end of the valve shaft 34 facing the top surface of the check valve 1) are each inserted into the cylindrical portion 16 (lower end cylindrical portion 16a and upper end cylindrical portion 16b) fixed to the valve box 10. The cylindrical lower end portion 16a, into which the lower end portion 34a is inserted, is fixed to the wall portion 19 (piping wall portion 19a or valve cylinder wall portion 19b) of the valve box 10. Specifically, as shown in FIG. 6, the lower end portion 34a of the valve stem 34 is supported by support portions 18 (first support portion 18a and second support portion 18b). In this embodiment, the support portions 18 protrude from the wall portion 19 (piping wall portion 19a or valve cylinder wall portion 19b) of the valve box 10 and extend toward the lower end portion 34a. More specifically, as shown in FIG. 6, each support portion 18 extends toward a ring portion 18c in the center of the pipe portion 11. The ring portion 18c and each support portion 18 are formed integrally. Furthermore, a portion of the cylindrical lower end portion 16a (see FIG. 2) is inserted into and connected to the ring portion 18c. In this embodiment, the lower end 34a is supported by two or more (four) support portions 18. The four support portions 18 are arranged in a plus (+) shape. Also, as shown in Fig. 2, in this embodiment, each of the second support portions 18b protrudes from the top of a protruding portion 11e or a top of a second protruding portion 11f, which will be described later. 2, the upper tubular end portion 16b into which the upper end portion 34b is inserted is fixed to the ceiling portion 15. More specifically, the upper tubular end portion 16b is fixed to the ceiling portion 15 so that the interior of the upper tubular end portion 16b communicates with the ceiling cavity 15a. The internal space of the upper tubular end portion 16b is aligned with the ceiling cavity 15a in the movement direction of the movable body 30. In this embodiment, the upper tubular end portion 16b is fitted into and fixed to the ceiling portion 15.

[0023] When the check valve 1 transitions from an open state to a closed state, or from a closed state to an open state, the valve stem 34 slides on the inner walls of the lower cylindrical end portion 16a and the upper cylindrical end portion 16b. 2, when the check valve 1 is in the closed state, the upper end 34b of the valve stem 34 is inserted into the upper cylindrical end portion 16b (particularly the lower end thereof), and the lower end 34a of the valve stem 34 penetrates the lower cylindrical end portion 16a and the ring portion 18c. At this time, the lower end 34a of the valve stem 34 is close to the pipe wall portion 19a. In this embodiment, the separation distance between the lower end 34a and the pipe wall portion 19a (the distance between the lower end 34a and the pipe wall portion 19a in the movement direction of the movable body 30) is smaller than the insertion depth of the upper end 34b into the upper cylindrical end portion 16b (the length of the portion of the upper end 34b that is inserted into the upper cylindrical end portion 16b, which is the length in the movement direction of the movable body 30). Since the valve stem 34 extends downward to such an extent that it is very close to the pipe wall portion 19a when the check valve 1 is in the closed state, the valve stem 34 can be inserted to a sufficient insertion depth into the lower cylindrical end portion 16a when the check valve 1 is in the open state. On the other hand, since the valve stem 34 is inserted to a sufficiently large depth into the upper cylindrical end portion 16b when the check valve 1 is in the closed state, the valve stem 34 is sufficiently supported by the upper cylindrical end portion 16b when in the closed state. On the other hand, as shown in FIG. 3, when the check valve 1 is in an open state, the upper end 34b of the valve shaft 34 penetrates the upper cylindrical end portion 16b. The portion of the upper end 34b that protrudes upward from the upper cylindrical end portion 16b is disposed within the ceiling cavity 15a. On the other hand, the lower end 34a of the valve shaft 34 is inserted into the lower cylindrical end portion 16a (particularly its upper end). The insertion depth of the lower end 34a of the valve shaft 34 into the lower cylindrical end portion 16a in the open state (the length of the portion of the lower end 34a that is inserted into the lower cylindrical end portion 16a, in the direction of movement of the movable body 30) is preferably greater than the distance between the lower end 34a and the pipe wall portion 19a when the check valve 1 is in a closed state (see FIG. 2). This allows the lower end 34a of the valve shaft 34 to be adequately supported by the lower cylindrical end portion 16a.

[0024] As shown in FIG. 8(b), the valve body 32 in this embodiment includes a sealing portion 36, a first gripping portion 38, and a second gripping portion 39. As shown in FIG. 2, the sealing portion 36 is a member that comes into close contact with the valve seat 12 in the closed state. The first gripping portion 38 is a member that is arranged on the top surface side of the valve cylinder 14 in the sealing portion 36. The second gripping portion 39 is a member that is arranged on the bottom surface side of the check valve 1 in the sealing portion 36. The sealing portion 36 is sandwiched between the first gripping portion 38 and the second gripping portion 39 in the movement direction. That is, the valve body 32 in this embodiment is formed by stacking the second gripping portion 39, the sealing portion 36, and the first gripping portion 38 in this order from bottom to top. In this embodiment, the sealing portion 36 is a packing made of resin, while the first gripping portion 38 and the second gripping portion 39 are made of metal. In this embodiment, the center of the second gripping portion 39 has a recess 39a formed so as to recess upward in the movement direction of the movable body 30. Similarly, the center of the first gripping portion 38 has a recess 38a formed so as to recess upward in the movement direction of the movable body 30. As shown in Fig. 2, when the check valve 1 is in the closed state, at least a portion of the tubular lower end portion 16a can be accommodated inside the recess 38a and the recess 39a (see Fig. 8(b)). 8(b), in this embodiment, the wall portion defining the recess 39a is spaced apart from the valve stem 34 in the radial direction of the valve cylinder 14. That is, a lower end hollow portion 39b, which is a hollow portion, is located between the valve stem 34 and the second gripping portion 39 in the radial direction of the valve cylinder 14. Furthermore, the wall portion of the first gripping portion 38 defining the recess 38a is spaced apart from the wall portion of the second gripping portion 39 defining the recess 39a, and a valve body hollow portion 38b, which is a hollow portion, is located between the first gripping portion 38 and the second gripping portion 39 in the radial direction of the valve cylinder 14. Because the lower hollow portion 39b that opens downward is formed in the lower part of the valve body 32, part of the fluid 200 that flows in from upstream can remain inside or near the lower hollow portion 39b. Therefore, when the check valve 1 is in the open state, the valve opening degree is likely to be maintained.

[0025] As shown in FIG. 2 , in this embodiment, the surface of the valve element 32 facing the upstream side (the lower surface 39d of the valve element 32, which is the surface of the second gripping portion 39 facing downward in the direction of movement of the movable body 30) is a convex surface having a convex shape facing the upstream side. In this embodiment, the radius of curvature of the lower surface 39d is relatively large. Specifically, when viewed in the width direction (left-right direction) of the check valve 1, the extension direction of a portion of the upstream side of the lower surface 39d (a portion of the lower surface 39d from the center of the lower surface 39d to the upstream end of the lower surface 39d) has a main axis component and a radial component of the valve cylinder 14, and further has a radial component that is larger than the main axis component. The extension direction of the upstream part of the lower surface 39d when viewed in the left-right direction may be the extension direction of a line connecting the center of the lower surface 39d when viewed in the left-right direction to the upstream end of the lower surface 39d. Because the lower surface 39d of the valve body 32 is convex, the flow direction of the first main current can be changed with little pressure loss, even when the first main current flows in the direction of movement of the moving body 30, as described below, compared to when the lower surface 39d is a flat surface along the radial direction of the valve cylinder 14. 8(a), the second grip portion 39 is formed to include a hollow portion 39c. Specifically, the plurality of hollow portions 39c are arranged side by side so as to surround the periphery of the valve stem 34. The hollow portions 39c are separated from one another by partitions extending in the movement direction of the movable body 30. The partitions make it easier for the shape of the valve element 32 to be maintained even when the valve element 32 is repeatedly pressed against the valve seat 12. Alternatively, the second gripping portion 39 may have a hollow portion 39c extending in the circumferential direction of the valve cylinder 14 disposed therein.

[0026] 2 and 3, the movable body 30 in this embodiment includes a spring body 37. Specifically, the spring body 37 is a coil spring whose axis is the movement direction of the movable body 30. The spring body 37 is disposed between the ceiling portion 15 and the valve body 32 in the movement direction of the movable body 30, and biases the ceiling portion 15 and the valve body 32. In this embodiment, both end faces of the spring body 37 are aligned along a plane extending perpendicular to the movement direction of the movable body 30 (a plane extending radially of the valve cylinder 14). Specifically, the end faces of the metal wire constituting the coil spring extend in a direction perpendicular to the movement direction of the movable body 30. Alternatively, the ends of the metal wire constituting the coil spring extend on a plane extending radially of the valve cylinder 14. In other words, the ends of the metal wire constituting the coil spring extend along the circumferential direction of the valve stem 34. This allows each of the end faces of the spring body 37 to come into surface contact with the ceiling portion 15 and the valve body 32, respectively. As a result, the spring body 37 can bias the ceiling portion 15 and the valve body 32 in a straight direction in the movement direction of the movable body 30. When the check valve 1 transitions from the closed state to the open state, the spring body 37 is compressed in the direction of movement of the movable body 30. Therefore, when the check valve 1 is in the open state, the spring body 37 urges the valve element 32 downward in the direction of movement of the movable body 30, and the spring body 37 urges the valve element 32 so that the check valve 1 is in the closed state. Also, when the check valve 1 is in the closed state, the spring body 37 urges the valve element 32 downward in the direction of movement of the movable body 30. Therefore, when the check valve 1 is in the closed state, the valve element 32 is in pressure contact with the valve seat 12.

[0027] Next, the flow of the fluid 200 when the fluid 200 passes through the check valve 1 of this embodiment will be described. 4(a) is a velocity distribution diagram showing the distribution of the velocity of the fluid 200 when the check valve 1 is installed midway through the piping and the fluid 200 flows at a flow velocity of 4.0 m / s into the piping upstream of the check valve 1. The line shown in the fluid 200 indicates the direction in which the fluid 200 flows. The velocity distribution diagrams in Figures 4(a) and 4(b) were created by creating a 3D model of the check valve corresponding to the shape of the check valve 1 of this embodiment and 3D models of the upstream and downstream piping connected to the check valve, and calculating the flow velocity of the fluid flowing through the check valve 1 through a simulation based on computational fluid dynamics. The simulation was performed under the assumption that the position of the valve element 32 (corresponding to the valve opening described below) was fixed and that a fluid 200 was flowing at a mass flow rate corresponding to a predetermined flow velocity. The same applies to Figures 5(a), 5(b), 12, 13(a), and 13(b) above. The valve opening in FIGS. 4(a) and 4(b) is approximately 80%. The valve opening is an index representing the degree of opening or closing of the valve disc 32. The valve opening is defined as 0% when the valve disc 32 is seated on the valve seat 12, and 100% when the lower end of the valve disc 32 (the lower left part of the valve disc 32 in FIG. 4(a)) is at the same height as the upper surface of the piping section 11 in the vertical direction. In other words, at 0% valve opening, the fluid 200 does not substantially move from the primary flow path 40 to the secondary flow path 50. At 100% valve opening, the fluid 200 is not substantially impeded by the valve disc 32 from moving from the primary flow path 40 to the secondary flow path 50 in the piping section 11. The valve opening is the position of the valve disc 32 in the vertical direction, expressed from 0 to 100%, based on the positions of the valve disc 32 at 0% valve opening and the valve disc 32 at 100% valve opening. However, in this embodiment, the valve opening degree is 80% when the valve element 32 is in the uppermost position. In other words, in the check valve 1 of this embodiment, the lower end of the valve element 32 does not rise to a position at the same height as the upper surface of the piping section 11 in the vertical direction, the maximum valve opening degree is 80%, and the valve opening degree does not take a value greater than 80%. Specifically, when the valve element 32 moves upward in the movement direction of the movable body 30 to a position where the valve opening degree is 80%, the upper end 34b of the valve stem 34 abuts against the ceiling section 15 (more specifically, the upper surface that defines the ceiling cavity section 15a), and therefore the valve stem 34 and valve element 32 cannot move to a position above the position where the valve opening degree is 80%.

[0028] When the check valve 1 is in an open state, the fluid 200 flows mainly from the primary flow path 40 to the secondary flow path 50 within the piping section 11. More specifically, the fluid 200 flows from the primary flow path 40 into the valve cylinder 14 and flows out of the valve cylinder 14 to the secondary flow path 50. As described above, the flow direction of the first main flow of the fluid 200 passing through the inside of the valve cylinder 14 from the upstream side (primary flow path 40) to the downstream side (secondary flow path 50) has more components in the direction of movement of the movable body 30 than in the direction of the main axis. The flow direction of the first main flow refers to the average flow direction of the first main flow. Here, the first main flow refers to a main portion of the fluid 200 that flows into the valve cylinder 14 from the primary flow path 40 and attempts to flow out into the secondary flow path 50. That is, the portion of the fluid 200 that flows from the primary flow path 40 into the valve cylinder 14 and flows out into the secondary flow path 50 without flowing back is the first main flow. In other words, the fluid 200 that flows into the valve cylinder 14 from the primary flow path 40 but flows in the main axial direction from the secondary flow path 50 toward the primary flow path 40 is not included in the first main flow. Specifically, the portion of the fluid 200 that flows below the valve element 32 in the movement direction of the movable body 30 inside the valve cylinder 14 (the portion of the fluid 200 indicated by region A in FIG. 4(b)) can become the first main flow. In this embodiment, the portion of the fluid 200 upstream (to the right) of the valve stem 34 in region A in FIG. 4(b) has a spiral flow direction. On the other hand, in region A in FIG. 4(b), a portion of the fluid 200 downstream (left side) of the valve stem 34 (a portion of the fluid 200 shown in region B in FIG. 4(b)) has a flow direction toward the secondary flow path 50. Therefore, the first main flow in this embodiment can be the portion of the fluid 200 shown in region B. The first main flow that flows from the primary flow path 40 into the lower end of the valve cylinder 14 flows in a direction that has a large component in the direction of movement of the movable body 30 (a direction toward the upper left in FIG. 4(a)). Thereafter, the first main flow flows out from between the valve element 32 and the valve seat 12 into the secondary flow path 50.

[0029] 5(a) and 5(b) are longitudinal cross-sectional views of a check valve 1 installed midway through a pipe, showing the velocity distribution of a fluid 200 when the fluid 200 flows into the pipe upstream of the check valve 1 at flow velocities of 2.0 m / s and 3.0 m / s, respectively. The valve opening in Fig. 5(a) is about 50%, and the valve opening in Fig. 5(b) is about 70%. In this embodiment, the greater the valve opening, the greater the component in the direction of movement of the moving body 30 in the flow direction of the first main current. In other words, the greater the flow velocity of the fluid 200 flowing into the check valve 1, the greater the component in the direction of movement of the moving body 30 in the flow direction of the first main current. The greater the valve opening, the more compressed the spring element 37 is, and a greater upward force in the movement direction must be applied to the valve element 32 to maintain the open state of the valve element 32. As described above, when the valve opening is large, the flow direction of the first main flow has a large movement direction component, making it easier to maintain the open state of the valve element 32. Furthermore, when the valve opening is small and the open state of the valve element 32 is relatively easily maintained, the flow direction of the first main flow has a large main axial component compared to when the valve opening is large, making it easier for the fluid 200 to flow smoothly from upstream to downstream. Furthermore, when the valve opening is 30% or more, the movement direction component of the moving body 30 in the flow direction of the first main current is stably larger than the main axis direction component. When the valve opening is 50% or more, the movement direction component of the moving body 30 in the flow direction of the first main current is more stably larger than the main axis direction component. Furthermore, when the valve opening is 80% or more, the movement direction component of the moving body 30 in the flow direction of the first main current is more stably larger than the main axis direction component.

[0030] In this embodiment, the check valve 1 has a flow direction guiding means that guides the fluid 200 to flow in the movement direction of the moving body 30, thereby realizing that the flow direction of the first main flow has more components in the movement direction of the moving body 30 than in the main axis direction. The flow direction guiding means in this embodiment has a predetermined structure. For example, the above-described flow direction of the first main stream is realized by including at least a part, preferably at least two or more, and more preferably at least three or more of the following structures: However, as typified by the structure of Patent Document 1 described below, even if at least a part of the following structures is included, if a structure that obstructs the first main stream from flowing in the movement direction of the moving body 30 is included, the above-described flow direction of the first main stream may not be realized. First, in this embodiment, as described above, the valve stem 34 extends downward from the valve element 32 in the movement direction of the movable body 30. This allows the fluid 200 that flows from the primary flow path 40 into the valve cylinder 14 to flow along the valve stem 34 in a direction that coincides with the movement direction of the movable body. In particular, in this embodiment, when the check valve 1 is in the open state, the valve stem 34 extends from the valve element 32 to the lower end cylindrical portion 16a and the ring portion 18c in the movement direction of the movable body 30. This makes it easy for the flow direction of the fluid 200 to be along the valve stem 34, regardless of the valve opening degree. Second, in this embodiment, when the check valve 1 is in the closed state, the lower end 34a of the valve stem 34 protrudes downward from the ring portion 18c in the movement direction of the movable body 30. In other words, when the check valve 1 is in the closed state, the lower end 34a of the valve stem 34 is located upstream of the ring portion 18c in the main axial direction. This can encourage the flow direction of the fluid 200 flowing from upstream to be redirected along the movement direction of the movable body 30. Particularly in this embodiment, when the check valve 1 is in the closed state, the lowermost end of the valve stem 34 is located vertically below the apex of the protruding portion 11e. Furthermore, in this embodiment, as will be described in detail separately, the closer the lower end 34a of the valve stem 34 is to the bottom surface of the pipe wall portion 19a, the longer the lower end 34a of the valve stem 34 extends downward in the movement direction from the ring portion 18c. This structure can more effectively redirect the flow direction of the fluid 200 along the movement direction of the movable body 30. Thirdly, in this embodiment, as will be described later, the width direction of one support portion 18 (particularly the support portion 18 of the second support portion 18b that is positioned below the valve stem 34) has a movement direction component, so that the flow direction of the fluid 200 that passes near the support portion 18 changes, and the fluid 200 can flow in a predetermined direction. Fourth, as described in detail elsewhere, the starting point of the upward slope 11c is located downstream of the lowest end or the ring portion 18c of the lower end tubular portion 16a. As a result, the fluid 200 flowing from upstream collides with the upward slope 11c downstream of the lowest end or the ring portion 18c. That is, the fluid 200 mainly flows from the primary flow path 40 into the valve cylinder 14 after passing the lowest end or the ring portion 18c. That is, the flow direction of the fluid 200 flowing in the main axis direction is more abruptly changed compared to when the starting point of the upward slope 11c is located upstream of the lowest end or the ring portion 18c. In other words, compared to when the starting point of the upward slope 11c is located upstream of the lowest end or the ring portion 18c, the flow direction of the fluid 200 flowing in the main axis direction can be changed to a direction that includes a component in the direction of movement of the large moving body 30. Fifth, as will be described later, the longitudinal direction of one support portion 18 (particularly, the support portion 18 of the second support portion 18b that is arranged below the valve stem 34) is slightly inclined with respect to the radial direction of the valve cylinder 14. Specifically, the support portion 18 is inclined downward in the movement direction of the moving body 30 as it approaches the center of the valve cylinder 14. As a result, a portion of the fluid 200 closer to the center as viewed in the main axis direction (a portion of the fluid 200 with a higher flow velocity) comes into contact with the second support portion 18b first. Therefore, the flow direction of the fluid 200 can be more effectively redirected to a direction that coincides with the movement direction of the moving body 30. The flow direction guide means is not limited to the first to fifth structures described above in this embodiment. For example, a member (excluding the valve stem 34) extending in the moving direction of the movable body 30 may be disposed inside the valve cylinder 14, or a protrusion such as a valve for changing the flow direction of the fluid 200 may be disposed in the primary flow path 40 or the valve cylinder 14. Preferably, the check valve 1 has the third and fifth structures described above. More preferably, the check valve 1 has the second structure in addition to the third and fifth structures described above. Or, even more preferably, the check valve 1 has the fourth structure in addition to the third and fifth structures described above. Alternatively, preferably, the check valve 1 has the first, second, and fourth structures described above. More preferably, the check valve 1 has the third structure described above in addition to the first, second, and fourth structures described above. Alternatively, the check valve 1 has the fifth structure described above in addition to the first, second, and fourth structures described above. In the check valve of Patent Document 1, whether the valve opening is small or large, the flow direction of the first main current does not have a larger component in the direction of movement of the moving body (disk 16) than in the main axial direction. Specifically, in the check valve of Patent Document 1, it is clearly stated that the fluid path is substantially straight from one side of the valve to the other (lines 90 to 100, page 1 of Patent Document 1). More specifically, the check valve of Patent Document 1 does not partially have the first structure described above, and does not particularly have the second structure. In Patent Document 1, the valve disc (disk 16) is not fixed to the valve stem (stem 17), and in the closed state, the valve disc is located at the lowest end of the valve stem. Therefore, in the closed state, the valve stem does not extend downward from the valve disc. Furthermore, the check valve of Patent Document 1 does not have the third to fifth structures described above. Furthermore, as shown in FIG. 3 of Patent Document 1, in the check valve of Patent Document 1, the width direction of the vanes (21) provided on the valve seat (15) is a direction intersecting the moving direction of the valve element (disk (16)). As a result, the fluid that collides with the vanes (21) is guided to flow in a direction intersecting the moving direction of the valve element (disk (16)). That is, in Patent Document 1, the first main flow is unlikely to flow along the moving direction of the moving element (disk (16)). As a result, in Patent Document 1, the first main flow flows linearly from upstream to downstream as described in the document.

[0031] As described above, it is preferable that the pressure loss when the fluid 200 passes through the check valve 1 is small, even if the flow direction of the first main current has a large component in the direction of movement of the moving body 30. In this embodiment, the first main current flows near the main axis. Specifically, as shown in Figures 4(a) and 4(b), when the valve opening is 30% or more, the first main current flows across the main axis (the axis indicated by the dashed line in Figure 4(a)). This can be achieved by arranging the lower end of the valve sleeve 14 (which is also the apex of the protruding portion 11e) closer to the bottom in the vertical direction than the main axis, and by arranging the valve element 32 closer to the top in the vertical direction than the main axis. By having the first main current flow near the main axis, pressure loss before and after flowing through the check valve 1 is reduced.

[0032] Moreover, in this embodiment, the fluid 200 in a portion of the first main flow that is close to the valve stem 34 (the right half of region B) flows in a direction having a large upward component, and the fluid 200 in a portion of the first main flow that is closer to the secondary flow path 50 than the portion of the first main flow (the left half of region B) flows in a direction having a large leftward component. More specifically, the flow direction of the fluid in a portion of the first main flow that is close to the valve stem 34 (the upstream (right) region of region B) has a larger movement direction component than the flow direction of the fluid 200 in a portion of the first main flow that is closer to the secondary flow path 50 than the portion of the first main flow (the downstream (left) region of region B). In this embodiment, the flow velocity of the fluid 200 in a portion of the first main flow close to the valve stem 34 (the right half of region B) is lower than the flow velocity of the fluid 200 in a portion of the first main flow closer to the secondary flow path 50 (the left half of region B). That is, the flow velocity is relatively low in the portion of the first main flow closer to the valve stem 34, particularly in the direction of movement of the movable body 30, and relatively high in the portion of the first main flow away from the valve stem 34, particularly in the direction of the main axis. This allows the fluid 200 to flow mainly from upstream to downstream in the main axis direction while pushing the valve element 32 upward in the direction of movement of the movable body 30. This configuration reduces pressure loss before and after flowing through the check valve 1.

[0033] In this embodiment, as described above, the maximum valve opening degree is 80%. In other words, when the check valve 1 is most open, the lower end of the valve element 32 is located below the top surface of the pipe 11 in the vertical direction. When the fluid 200 flows from the primary flow path 40 into the valve cylinder 14, a portion of the fluid 200 flows in the direction of movement of the movable body 30. Because the lower end of the valve element 32 is located below the top surface of the pipe 11, the fluid 200 that flows into the valve cylinder 14 collides with the valve element 32 at a position below the top surface of the pipe 11. As a result, the fluid 200 changes its flow direction below the top surface of the pipe 11, and after the collision, the fluid 200 can flow along the main axis direction through approximately the center of the pipe 11. In this way, the fluid 200 that flows into the valve cylinder 14 flows out to the approximately center of the pipe 11, where it is less affected by friction with the inner wall of the pipe 11, allowing the fluid 200 to pass through the check valve 1 with little pressure loss.

[0034] In this embodiment, as particularly shown in FIG. 5(a), the second main flow of the fluid flowing out from the valve cylinder 14 to the secondary flow path 50 (the main flow of the fluid 200 in region C in FIG. 5(a)) flows in a direction inclined obliquely toward the bottom surface of the check valve with respect to the main axis direction. In other words, the second main flow flows obliquely downward with respect to the main axis direction. As a result, the second main flow flows along the downward slope of the downstream flow path, thereby suppressing turbulence near the downward slope (fluid flow that bounces off the downward slope). The second main flow is a main part of the fluid 200 that flows out from the inside of the valve cylinder 14 to the secondary flow path 50 . In this embodiment, the flow direction of the second main flow has a main axial component and a vertical component. In this embodiment, the flow direction of the second main flow has a main axial component that is larger than the vertical component. In this embodiment, the smaller the valve opening, the larger the downward component of the second main flow. Specifically, as shown in Fig. 5(b), even when the valve opening is about 70%, the flow direction of the second main flow has a downward component, similar to the case shown in Fig. 5(a).

[0035] The second main flow has a width in the vertical direction. The vertical direction is the direction from the main axis direction toward the top side (upper side) of the valve box 10, where the valve sleeve 14 is provided, to the bottom side (lower side) opposite the top side. In other words, the vertical direction corresponds to the up-down direction in this embodiment. In this embodiment, the flow velocity of the second main flow in the lower flow area, which is closer to the bottom than the vertical center, is greater than the flow velocity in the upper flow area, which is closer to the top than the vertical center. As a result, even if the direction in which the fluid flows out of the valve cylinder (the flow direction of the second main flow) is obliquely downward as described above, the high flow velocity in the lower flow area makes it easier for the flow direction of the main flow of the fluid 200 to naturally return to a horizontal direction. This flow velocity distribution may be achieved by the amount of protrusion of the protrusion portion 11e (see FIG. 2) on the valve box 10, as described below, or by other structures. For example, the above-described flow velocity distribution may be achieved by the position of the valve stem 34 or the lower end tubular portion 16a. Specifically, the average flow velocity in the lower half of region C (lower flow area) shown in Figure 4(b) is greater than the average flow velocity in the upper half of region C (upper region). More specifically, the high flow velocity region in region C (region D) (region of 6.5 m / s or more) is distributed unevenly in the lower half of region C.

[0036] In this embodiment, the bottom surface of the piping section 11 protrudes (upward) toward the top surface in the vertical direction. Specifically, a portion of the bottom surface of the piping section 11, including the valve seat 12, protrudes upward. More specifically, the bottom surface of the piping section 11 includes an upward slope 11c and a downward slope 11d. The upward slope 11c is a portion of the bottom surface that extends obliquely upward from the upstream side toward the valve seat 12 on the primary flow path 40 side. The downward slope 11d is a portion of the bottom surface that extends obliquely downward from the valve seat 12 toward the downstream side on the secondary flow path 50 side. The portion of the bottom surface of the piping section 11 that protrudes upward is called the protruding portion 11e. The protruding portion 11e can also be considered a mountain-shaped portion formed by the upward slope 11c and the downward slope 11d in the vertical cross section of the check valve 1. In this embodiment, the top of the protruding portion 11e or its vicinity also forms part of the valve seat 12. In this embodiment, the apex of the protruding portion 11e is located closer to the bottom surface side than the main axis of the piping portion 11 in the vertical direction. In this embodiment, as shown in FIG. 2 , a portion of the valve box 10 supporting the lower end of the valve stem 34 (the ring portion 18c or the tubular lower end portion 16a, or both) is disposed closer to the top surface in the vertical direction (upward in the up-down direction) than the protruding portion 11e. In other words, this portion is disposed higher than the lower end of the valve seat 12 (a lower portion of the ring-shaped valve seat in the up-down direction). In other words, when viewed in the main axis direction (front-rear direction), at least a portion of the ring portion 18c or the tubular lower end portion 16a is disposed inside the annular valve seat 12. This prevents the portion from interfering with the movement of the fluid 200 from the primary flow path 40 to the secondary flow path 50. Furthermore, due to the reduced interference, the flow velocity in the lower flow area of ​​the second main flow is less likely to decrease. In other words, the flow velocity in the lower flow area of ​​the second main flow is likely to increase.

[0037] In this embodiment, the extension direction of the upward slope 11c when viewed from the width direction (left-right direction) of the check valve 1 has a main axis direction component that is larger than the vertical direction component. In other words, the upward slope 11c is a gentle upward slope. Since the upward slope 11c extends along the main axis direction in this manner, the amount of protrusion of the protruding portion 11e is reduced, which increases the inner diameter of the valve seat 12 and allows the fluid 200 to move more smoothly. Here, if the upward slope 11c is curved, the extension direction of the upward slope 11c when viewed from the left-right direction is the direction of a straight line connecting the start point of the upward slope 11c (the lowest part of the upward slope 11c, which is also the most upstream part of the upward slope 11c) and the apex of the upward slope 11c (the uppermost part of the upward slope 11c, which is also the most downstream part of the upward slope 11c). In this embodiment, the starting point of the upward slope 11c is located downstream in the main axis direction of at least a part of the valve box 10 that supports the lower end 34a of the valve stem 34 (the ring portion 18c or the lower cylindrical end portion 16a). This makes it difficult for the movement of the fluid 200, which is guided upward in the movement direction of the movable body 30 by the upward slope 11c, to be obstructed by the ring portion 18c or the lower cylindrical end portion 16a. In this embodiment, the apex of the protruding portion 11e (the boundary between the upward slope 11c and the downward slope 11d) is located downstream of the lower tubular end portion 16a in the axial direction. More specifically, the apex of the protruding portion 11e is located downstream of the entire lower tubular end portion 16a in the axial direction. This makes it difficult for the lower tubular end portion 16a to obstruct the movement of the fluid 200 that is guided upward in the movement direction of the movable body 30 by the upward slope 11c.

[0038] As shown in FIG. 2, in this embodiment, the upper surface (wall portion 19 on the top side in the vertical direction) of the piping section 11 that defines the primary flow path 40 has a second protruding portion 11f that protrudes downward toward the bottom surface. In this embodiment, the top of the second protruding portion 11f or its vicinity also forms part of the valve seat 12. The surface of the second protruding portion 11f includes an inclined surface 11g that slopes downward from upstream to downstream. In this embodiment, the extension direction of the inclined surface 11g when viewed in the width direction of the check valve 1 includes a main axis direction component that is larger than the vertical direction component. Because the inclined surface 11g extends along the main axis in this way, the protruding amount of the second protruding portion 11f is reduced, thereby increasing the inner diameter of the valve seat 12 and enabling smoother movement of the fluid 200. In addition, in this embodiment, the apex of the second protrusion portion 11f (the part of the second protrusion portion 11f that protrudes most downward) is positioned upstream in the main axis direction of at least a part of the part (ring portion 18c or lower end cylindrical portion 16a) that supports the lower end portion 34a of the valve shaft 34 in the valve box 10. In this embodiment, the apex of the second protruding portion 11f is disposed closer to the ceiling surface in the vertical direction than a portion (the ring portion 18c or the lower cylindrical end portion 16a) that supports the lower end portion 34a of the valve stem 34 in the valve box 10. More specifically, the apex of the second protruding portion 11f is disposed closer to the ceiling surface in the vertical direction than the entire ring portion 18c and the entire lower cylindrical end portion 16a.

[0039] As described above, the lower end of the valve stem 34 is supported by the support portion 18. As shown in Fig. 6, in this embodiment, the support portion 18 includes a first support portion 18a and a second support portion 18b. The first support portion 18a and the second support portion 18b extend radially from the ring portion 18c toward the wall portion 19 of the valve cylinder 14. In this embodiment, the first support portion 18a extends along the width direction of the check valve 1 and extends perpendicular to the movement direction. On the other hand, as shown in Fig. 2, the second support portion 18b extends along the vertical direction (up-down direction) and extends at an angle (toward the lower right in the figure) toward the lower end portion 34a of the valve shaft 34 in a direction toward the bottom side of the check valve 1 in the movement direction of the movable body 30, relative to the direction perpendicular to the movement direction of the movable body 30 (the radial direction of the valve cylinder 14). Here, "the second support portion 18b extending along the vertical direction" means that the extension direction of the second support portion 18b has a vertical component. The second support portion 18b being inclined toward the bottom side of the check valve 1 in the movement direction of the moving body 30 toward the lower end portion 34a of the valve shaft 34 relative to the radial direction of the valve cylinder 14 means that the second support portion 18b extends in a direction inclined relative to the radial direction of the valve cylinder 14, and is inclined relative to the radial direction so that the closer it is to the lower end portion 34a, the closer it is to the lower side in the movement direction of the moving body 30. With the above configuration, the valve stem 34 is firmly held, while preventing the fluid 200 from colliding with the valve stem 34, the valve disc 32, etc., and damaging the valve stem 34, the valve disc 32, etc. Specifically, first, because the horizontally extending first support portion 18a is perpendicular to the valve stem 34, the function of the support portion 18 to firmly support the lower end portion 34a of the valve stem 34 can be fully demonstrated. Furthermore, because one end of the second support portion 18b, which is located toward the center of the flow path, is located protruding upstream, the second support portion 18b causes the fluid 200, which is flowing fastest in the center of the flow path, to slow down when it hits the one end of the second support portion 18b, and this prevents the fluid 200 from flowing suddenly into the valve cylinder 14.

[0040] In this embodiment, each support portion 18 has a plate shape. More specifically, the plate-shaped support portion 18 extends in the longitudinal direction and width direction, which will be described later. The support portion 18 is a member that is elongated in a predetermined direction, which is the longitudinal direction. The longitudinal direction of the support portion 18 coincides with the direction in which the support portion 18 extends from the wall portion 19 to the lower end portion 34a. The width direction is a direction perpendicular to the plate thickness direction and the longitudinal direction. In Figure 2, the cross-sectional outline of the first support portion 18a is shown by a dotted line. In this embodiment, the width direction of the first support portion 18a is along the main axis direction (front-rear direction). The width direction of the second support portion 18b is along the movement direction. Here, the width direction of the support portion 18 being along a predetermined direction means that the width direction has a component in the predetermined direction. Specifically, the width direction of the support portion 18 has a component in the predetermined direction that is larger than the component in the direction perpendicular to the predetermined direction. With the above configuration, the first support portion 18a guides the fluid 200 from the upstream side to the downstream side along the main axis direction, while the second support portion 18b guides the fluid 200 upward in the movement direction of the valve element 32. In other words, the flow direction can be maintained so that the valve element 32 can easily remain in an open state while suppressing pressure loss.

[0041] 6, the thickness direction of the first support portion 18a is the vertical direction (up-down direction), and the thickness direction of the second support portion 18b is the width direction (left-right direction) of the check valve 1. This makes it possible to reduce the area of ​​the support portion 18 when viewed from the rear. As a result, the movement of the fluid 200 flowing in from upstream is less likely to be hindered by the support portion 18.

[0042] 7(a), a groove 16d extending in the movement direction (vertical direction in the drawing) of the movable body 30 may be formed in a part of the inner wall (cylindrical portion inner wall 16c) of the cylindrical portion 16 (lower end cylindrical portion 16a) on the bottom side of the check valve 1 (a region of the cylindrical portion inner wall 16c facing the top surface). Such groove 16d allows the valve stem 34 to slide straight in the movement direction of the valve element 32 without twisting. In this embodiment, two grooves 16d are formed in the cylindrical inner wall 16c, but one groove 16d or three or more grooves 16d may be formed in the cylindrical inner wall 16c. Also, in this embodiment, the grooves 16d are formed only in a portion of the lower end of the cylindrical inner wall 16c, and are not formed in a portion of the upper end of the cylindrical inner wall 16c. Alternatively, the grooves 16d may extend from the upper end to the lower end of the cylindrical inner wall 16c. In this embodiment, as shown in FIG. 7(b), a groove 34c extending in the moving direction of the moving body 30 (up and down direction in the figure) is formed on the surface (outer peripheral surface) of the lower end portion 34a. Both groove 16d in cylindrical inner wall 16c and groove 34c in the surface of lower end 34a may be formed, or groove 16d may not be formed in cylindrical inner wall 16c and groove 34c may be formed in the surface of lower end 34a. In this embodiment, groove 34c is formed only in a portion of the lower end side of the surface of lower end 34a and is not formed in a portion of the upper end side of the surface. Similarly to the groove 16d in the lower end cylindrical portion 16a, a groove (not shown) extending in the direction of movement of the movable body 30 may be formed in part of the bottom surface side of the check valve 1 on the inner wall of the upper end cylindrical portion 16b. Similar to the groove 34c on the surface of the lower end 34a, a groove (not shown) extending in the moving direction of the moving body 30 may also be formed on the surface (outer peripheral surface) of the upper end 34b of the valve stem 34.

[0043] In this embodiment, as shown in FIGS. 8(a) and 8(b), a sealing recess 36a is formed in the center of the lower surface 36b of the sealing portion 36, which faces the bottom side of the check valve 1. The sealing recess 36a is a recess that is recessed toward the inside of the sealing portion 36 from the outer periphery of the lower surface 36b of the sealing portion 36. The depth dimension D1 of a portion of the bottom side of the sealing recess 36a may be larger than the depth dimension of other portions. For example, the depth dimension D1 may be larger than the depth dimension D2 of a portion of the ceiling side of the sealing recess 36a. Alternatively, the depth dimension D1 may be larger than the depth dimension of a portion of the right or left side of the sealing recess 36a. In FIGS. 8(a) and 8(b), the depth of the sealing recess 36a and the relationship between the depth dimension D1 and the depth dimension D2 are exaggerated. The depth of the sealing recess 36a or the difference between the depth dimension D1 and the depth dimension D2 may be smaller than those shown in FIGS. 8(a) and 8(b). A sealing recess 36a is formed in the sealing portion 36, and a portion of the sealing recess 36a on the bottom side is formed deep, which effectively prevents the sealing portion 36 and the second gripping portion 39 from becoming misaligned due to the fluid 200 flowing out of the valve cylinder 14 at a high speed. In this embodiment, the sealing recess 36a is formed so as to surround the periphery of the valve stem 34 when viewed in the movement direction of the movable body 30. Alternatively, when viewed in the movement direction of the movable body 30, the sealing recess 36a may be formed only in the area below (on the bottom surface side of) the lower surface 36b.

[0044] Second Embodiment Fig. 9 is a perspective view showing an example of the check valve 1 according to this embodiment. Fig. 12 to Fig. 13(b) show the velocity distribution of the fluid 200 when the check valve 1 is installed midway through a pipe and the fluid 200 is caused to flow into the pipe upstream of the check valve 1 at flow velocities of 4.0 m / s, 2.0 m / s, and 3.0 m / s, respectively. First, an overview of the check valve 1 of this embodiment will be described. In this embodiment, as shown in FIG. 12, the flow direction of the first main flow of the fluid 200 passing through the inside of the valve cylinder 14 from the upstream side to the downstream side (in this embodiment, the main flow of the fluid shown in region B in FIG. 12) has more components in the direction of movement of the moving body 30 than in the direction of the main axis.

[0045] Next, the check valve 1 of this embodiment will be described in detail. The check valve 1 of this embodiment differs from the first embodiment in the structure of the valve body 10 that supports the lower end portion 34a of the valve stem 34.

[0046] In this embodiment, the check valve 1 has the following structure in particular, so that the flow direction of the first main flow of the fluid 200 has more components in the movement direction of the moving body 30 than in the main axis direction. First, in this embodiment, the valve stem 34 extends downward from the valve element 32 in the movement direction of the movable body 30. Furthermore, when the check valve 1 is in the closed state, the lower end 34a of the valve stem 34 protrudes downward from the ring portion 18c in the movement direction of the movable body 30. Furthermore, the width direction of one of the support portions 18 (particularly the support portion 18e arranged below the valve stem 34) has a component in the movement direction. Furthermore, the starting point of the upward slope 11c is arranged at the lowest end of the lower end tubular portion 16a or downstream of the ring portion 18c.

[0047] 10 and 14, the tubular lower end portion 16a is supported by two support portions 18. Specifically, the two support portions 18 (upper support portion 18d and lower support portion 18e) extend in the vertical direction from a ring portion 18c that connects to the tubular lower end portion 16a. In this embodiment, no support portions 18 are disposed on either side of the ring portion 18c in the width direction (left-right direction) of the check valve 1, and fluid 200 can pass through the areas on both sides. Specifically, the upper support portion 18d protrudes from the upper surface of the piping portion 11 (the second protruding portion 11f on which the valve seat 12 is formed) toward the ring portion 18c. The lower support portion 18e protrudes from the middle of the upward slope 11c in the main axial direction toward the ring portion 18c. In other words, the lower support portion 18e protrudes from a position on the upward slope 11c that is upstream of the apex of the protruding portion 11e toward the ring portion 18c.

[0048] As shown in Figures 10 and 11, similar to the first embodiment, the upper support portion 18d and the lower support portion 18e have a plate shape. The thickness direction of the upper support portion 18d and the lower support portion 18e is the left-right direction. The longitudinal direction of the lower support portion 18e is a direction perpendicular to the movement direction of the moving body 30 (the radial direction of the valve cylinder 14). On the other hand, the longitudinal direction of the upper support portion 18d is inclined with respect to the radial direction of the valve cylinder 14. Specifically, the longitudinal direction of the upper support portion 18d is inclined downward in the movement direction of the moving body 30 as it approaches the lower end of the valve shaft 34 with respect to the radial direction of the valve cylinder 14.

[0049] In this embodiment, the apex of the protruding portion 11e (a part of the bottom surface side of the valve seat 12 in the vertical direction) is not located below a part (such as the ring portion 18c) of the valve box 10 that supports the lower end portion 34a of the valve stem 34. More specifically, the apex of the protruding portion 11e is located above a part of the ring portion 18c in the vertical direction.

[0050] In this embodiment, the surface of the valve body 32 facing the upstream side (the lower surface of the valve body 32, which is the surface of the second gripping portion 39 facing downward in the direction of movement of the movable body 30) is a flat surface extending in the radial direction of the valve cylinder 14. In this embodiment, the second gripping portion 39 is formed solid.

[0051] The check valve 1 in this embodiment has the following features, similar to the first embodiment. The second main flow of the fluid 200 flowing out from the valve cylinder 14 to the secondary flow path 50 flows in a direction inclined obliquely toward the bottom surface of the check valve 1 with respect to the main axial direction. In the second main flow, the flow velocity in the lower flow area located closer to the bottom surface than the center in the vertical direction is greater than the flow velocity in the upper flow area located closer to the top surface than the center. Both ends (upper end 34b and lower end 34a) of the valve shaft 34 are supported by the wall 19 of the valve box 10. The width direction of the support portion 18 (upper support portion 18d and lower support portion 18e) of this embodiment is aligned with the direction in which the moving body 30 moves. Furthermore, a groove 16d extending in the direction of movement of the moving body 30 is formed in a part of the inner wall of the lower end cylindrical portion 16a on the bottom side of the check valve 1. Furthermore, a sealing recess 36a is formed in the center of the lower surface 36b of the sealing portion 36, and the depth dimension of one portion of the sealing recess 36a on the bottom surface side is greater than the depth dimension of the other portion.

[0052] The present invention is not limited to the above-described embodiment, but includes various modifications and improvements as long as the object of the present invention is achieved. The following modifications can be combined as appropriate.

[0053] The above embodiment encompasses the following technical ideas. (1) A straight pipe joint type oblique lift check valve in which fluid flows from the upstream side to the downstream side, A valve seat; a movable body that is linearly reciprocable between a closed state in which it is in close contact with the valve seat and an open state in which it is separated from the valve seat; a valve box including a valve cylinder extending in the moving direction of the movable body and in which the movable body moves, and to which the valve seat is fixed; a primary flow path located upstream of the valve cylinder and having an axis parallel to a main axis of the linear flow path; a secondary flow passage located downstream of the valve cylinder and having an axis in the main axis direction, a flow direction of a first main flow of the fluid passing through the inside of the valve cylinder from the upstream side to the downstream side has a larger component in the movement direction of the movable body than a component in the main axis direction. (1-1) The check valve according to (1), wherein the flow direction of a portion of the first main flow path that is close to the valve stem has a component in the movement direction that is larger than the flow direction of another portion of the first main flow path that is closer to the secondary flow path than the portion of the first main flow path. (1-2) The check valve according to (1-1), wherein the flow velocity of the portion of the first main flow fluid that is closer to the valve stem is smaller than the flow velocity of the other portion of the first main flow fluid that is closer to the secondary flow path 50 than the portion of the first main flow fluid. (2) A check valve as described in (1), wherein a second main flow of the fluid flowing out from the valve cylinder to the secondary flow path flows in a direction inclined obliquely toward the bottom surface of the check valve with respect to the main axis direction. (2-1) The check valve according to (2), wherein the smaller the valve opening, the larger the component of the second main flow in the direction connecting the top side and the bottom side of the check valve. (3) The second main flow has a width in a vertical direction from the top side, which is the side on which the valve cylinder is provided in the valve box, to the bottom side, which is the opposite side of the top side, based on the main axis direction, The check valve according to (2), wherein in the second main flow, the flow velocity in a lower flow area closer to the bottom surface than the center in the vertical direction is greater than the flow velocity in an upper flow area closer to the top surface than the center. (4) The moving body is a valve body supported by the valve seat in the closed state; a valve stem extending from the valve body in both directions of the movement, The check valve according to any one of (1) to (3), wherein both ends of the valve stem are supported by the wall of the valve body. (5) The lower end of the valve shaft, which is the end on the bottom side of the check valve, The valve body is supported by two or more support portions that protrude from the wall portion of the valve body and extend toward the lower end portion, the first support portion extends along the width direction of the check valve and is perpendicular to the movement direction, The second support portion is The valve sleeve extends along a vertical direction from a top side, which is a side of the valve box where the valve cylinder is provided, to a bottom side, which is an opposite side of the top side, based on the main axis direction, The check valve according to (4), wherein the lower end is inclined in a direction perpendicular to the direction of movement toward the bottom surface side of the check valve in the direction of movement. (6) The support portion is It has a plate shape, The support portion extends in a longitudinal direction extending from the wall portion to the lower end portion, as well as in a plate thickness direction and a width direction perpendicular to the longitudinal direction, the width direction of the first support portion is aligned with the main axis direction, The check valve according to (5), wherein the width direction of the second support portion is aligned with the movement direction. (6-1) The check valve according to (6), wherein the thickness direction of the first support portion is the vertical direction, and the thickness direction of the second support portion is the width direction of the check valve. (7) The lower end portion of the valve shaft, which is the end portion on the bottom side of the check valve, The valve body is inserted into a cylindrical portion fixed to the wall portion of the valve body, The check valve according to any one of (4) to (6), wherein a groove extending in the movement direction is formed in a part of the inner wall of the cylindrical portion on the bottom side of the check valve. (7-1) The check valve according to (7), wherein a groove extending in the direction of movement of the moving body is formed on the outer peripheral surface of the lower end portion. (8) The valve body is a sealing portion that is in close contact with the valve seat in the closed state; a first gripping portion disposed on the top surface side of the valve cylinder in the sealing portion; a second gripping portion disposed on a bottom surface side of the check valve in the sealing portion, the sealing portion is sandwiched between the first gripping portion and the second gripping portion in the movement direction, a sealing recess formed in a central portion of a lower surface of the sealing portion facing the bottom surface of the check valve, the sealing recess being recessed more toward the inside of the sealing portion than an outer periphery of the lower surface; The check valve according to any one of (4) to (7), wherein a depth dimension of a portion of the sealing recess on the bottom surface side is greater than a depth dimension of another portion. (9) The upper end portion of the valve shaft, which is the end portion on the top surface side of the check valve, The valve body is inserted into an upper cylindrical portion fixed to the ceiling portion of the valve body, A check valve as described in any one of (4) to (8), wherein, in a closed state of the check valve, the distance in the movement direction between the lower end of the valve stem and a piping wall portion that defines the piping portion extending in the main axis direction is smaller than the insertion depth of the upper end of the valve stem into the upper end tubular portion. (10) A check valve described in any one of (4) to (9), wherein the insertion depth of the lower end of the valve stem into the lower end tubular portion when the check valve is in an open state is greater than the distance between the lower end of the valve stem when the check valve is in a closed state and the piping wall portion that defines the piping portion extending in the main axis direction. (11) The check valve according to any one of (1) to (10), wherein the larger the valve opening, the more the flow direction of the first main flow has a component in the direction of movement of the moving body. (12) A check valve according to any one of (1) to (11), wherein the greater the flow velocity of the fluid flowing into the check valve, the greater the component of the direction of movement of the moving body in the flow direction of the first main current. (13) The valve body has a piping portion extending in the main axis direction, a bottom surface of the piping portion including a protruding portion protruding toward a top surface side in a vertical direction, A check valve according to any one of (4) to (10), which cites (3), wherein a part of the valve box that supports the lower end of the valve stem is positioned closer to the top surface in the vertical direction than the protruding part. (14) The valve body has a piping portion extending in the main axis direction, the bottom surface of the piping section includes an upwardly inclined surface that is inclined upward from the upstream side to the downstream side toward the top surface side in the vertical direction, A check valve described in any one of (4) to (10), wherein the starting point of the upward slope is located downstream in the main axis direction of at least a portion of the part of the valve box that supports the lower end of the valve cylinder. (15) The check valve according to (13), wherein the apex of the protruding portion is located downstream of the lower end tubular portion in the main axis direction. (16) The valve body has a piping portion extending in the main axis direction, a part of the top surface side of the piping section that defines the primary flow path 40 includes a second protruding portion that protrudes toward the bottom surface side in the vertical direction, A check valve described in any one of (4) to (10), wherein the apex of the second protrusion portion is located upstream in the main axis direction of at least a portion of the portion of the valve body that supports the lower end of the valve stem. (17) The check valve according to (1), wherein the valve shaft extends from the valve body toward the bottom side of the check valve in the movement direction. (18) A check valve according to (1) or (17), wherein, in a closed state of the check valve, the lower end of the valve stem protrudes downward beyond the ring portion in the direction of movement of the movable body. (19) A check valve according to any one of (1), (17) and (18), wherein the width direction of one support part has a component in the movement direction. (20) A check valve described in any one of (1), (17), (18) or (19), in which the starting point of the upward slope in the pipe wall portion is located downstream of one end of the downstream end of the lower end tubular portion or downstream of the ring portion. (21) A check valve described in any one of (1), (17), (18), (19) or (20), wherein one support portion is inclined so that the closer it is to the center of the valve cylinder, the closer it is to the bottom side of the check valve in the direction of movement of the movable body. (22) The valve shaft extends from the valve body toward the bottom side of the check valve in the movement direction, When the check valve is in a closed state, the lower end of the valve stem projects downward beyond the ring portion in the moving direction of the movable body, The check valve according to (4), wherein the starting point of the upward slope in the pipe wall portion is located at one end on the downstream side of the lower end tubular portion or downstream of the ring portion. (23) The width direction of one support part has a component in the movement direction, The check valve according to (4), wherein the one support portion is inclined so that the closer it is to the center of the valve cylinder, the closer it is to the bottom side of the check valve in the direction of movement of the movable body. (24) The valve shaft extends from the valve body toward the bottom side of the check valve in the movement direction, The check valve according to (4), wherein the starting point of the upward slope in the pipe wall portion is located at one end on the downstream side of the lower end tubular portion or downstream of the ring portion. (25) The valve shaft extends from the valve body toward the bottom side of the check valve in the movement direction, The check valve according to (4), wherein, in a closed state of the check valve, the lower end of the valve stem protrudes downward beyond the ring portion in the moving direction of the movable body. (26) The valve shaft extends from the valve body toward the bottom side of the check valve in the movement direction, When the check valve is in a closed state, the lower end of the valve stem projects downward beyond the ring portion in the moving direction of the movable body, The check valve according to (4), wherein the one support portion is inclined so that the closer it is to the center of the valve cylinder, the closer it is to the bottom side of the check valve in the direction of movement of the movable body. [Explanation of symbols]

[0054] 1. Check valve 10 Valve box 11 Piping section 11a Inlet 11b Outlet 11c uphill 11d Downhill 11e Overhang 11f Second overhang 11g slope 12 Valve seat 14 Valve cylinder 15 Ceiling 15a Ceiling cavity 15b Fastener 16 Cylinder 16a Lower end cylinder part 16b Upper tube part 16c Inner wall of cylinder part 16d Groove 17 Tsuba 18 Support part 18a First support part 18b Second support part 18c ring section 18d Upper support part 18e Lower support part 19 Wall 19a Pipe wall 19b Valve barrel wall 30 Mobile 32 Valve body 34 Valve stem 34a Lower end 34b Upper end 34c Groove 34d Screw receiving part 35 Threaded screw 36 Sealing part 36a Sealing recess 36b Bottom side 37 Spring body 38 First grip part 38a Recess 38b Hollow portion of valve body 39 Second grip part 39a Recess 39b Lower end hollow part 39c Hollow part 40 Primary flow path 50 Secondary flow path 200 fluid

Claims

1. A straight pipe joint type oblique lift check valve in which fluid flows from the upstream side to the downstream side, A valve seat; a movable body that is linearly reciprocable between a closed state in which it is in close contact with the valve seat and an open state in which it is separated from the valve seat; a valve box including a valve cylinder extending in the moving direction of the movable body and in which the movable body moves, and to which the valve seat is fixed; a primary flow path located upstream of the valve cylinder and having a linear main axis as its axis; a secondary flow passage located downstream of the valve cylinder and having an axis center on the main shaft, The moving body is a valve body supported by the valve seat in the closed state; a valve stem extending from the valve body in both directions of the movement, a valve seat provided with a valve sleeve in a main axis direction, the valve seat being provided with a valve sleeve in a valve box; a valve seat having a valve sleeve in a main axis direction; a valve seat having a valve sleeve in a valve box; an interior of the valve cylinder including an interior region located closer to the bottom surface in the movement direction than the valve disc in the open state and located downstream in the main axis direction than the valve stem, a check valve in which, when a valve opening degree, which represents the position of the valve body in the vertical direction, is 30% or more, the flow direction of a first main stream of the fluid passing through the internal region of the valve cylinder from the upstream side to the downstream side has a greater component in the direction of movement of the movable body than a component in the direction of the main axis.

2. 2. The check valve according to claim 1, wherein a second main flow of the fluid flowing out from the valve cylinder to the secondary flow path flows in a direction obliquely inclined with respect to the main axis direction toward a bottom surface of the check valve.

3. The second main flow has a width in a vertical direction from a top side, which is a side on which the valve cylinder is provided in the valve box, to a bottom side, which is an opposite side to the top side, based on the main axis direction, The check valve according to claim 2 , wherein a flow velocity in a lower flow area closer to the bottom surface than a center in the vertical direction in the second main flow is greater than a flow velocity in an upper flow area closer to the top surface than the center.

4. A check valve as described in any one of claims 1 to 3, wherein both ends of the valve shaft are supported on the wall of the valve box.

5. The lower end portion of the valve shaft, which is the end portion of the check valve on the bottom side, The valve body is supported by two or more support portions that protrude from the wall portion of the valve body and extend toward the lower end portion, the first support portion extends along the width direction of the check valve and is perpendicular to the movement direction, The second support portion is The valve sleeve extends along a vertical direction from a top side, which is a side of the valve box where the valve cylinder is provided, to a bottom side, which is an opposite side of the top side, based on the main axis direction, The check valve according to claim 4 , wherein the lower end portion is inclined in a direction perpendicular to the movement direction toward a bottom surface side of the check valve in the movement direction.

6. The support portion is It has a plate shape, The support portion extends in a longitudinal direction extending from the wall portion to the lower end portion, as well as in a plate thickness direction and a width direction perpendicular to the longitudinal direction, the width direction of the first support portion is aligned with the main axis direction, The check valve according to claim 5 , wherein the width direction of the second support portion is aligned with the movement direction.

7. The lower end portion of the valve shaft, which is the end portion of the check valve on the bottom side, The valve body is inserted into a cylindrical portion fixed to the wall portion of the valve body, The check valve according to claim 4 , wherein a groove extending in the movement direction is formed in a part of the inner wall of the cylindrical portion on a bottom surface side of the check valve.

8. The valve body is a sealing portion that is in close contact with the valve seat in the closed state; a first gripping portion disposed on the top surface side of the valve cylinder in the sealing portion; a second gripping portion disposed on a bottom surface side of the check valve in the sealing portion, the sealing portion is sandwiched between the first gripping portion and the second gripping portion in the movement direction, a sealing recess formed in a central portion of a lower surface of the sealing portion facing the bottom surface of the check valve, the sealing recess being recessed more toward the inside of the sealing portion than an outer periphery of the lower surface; The check valve according to claim 4 , wherein a depth dimension of a portion of the sealing recess on the bottom surface side is greater than a depth dimension of another portion.

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