Check valve

Abstract

A check valve (1) includes a moving body (30), a valve casing (10), a valve cylinder (14), a primary flow path (40), and a secondary flow path (50). The moving body (30) is a member capable of linearly reciprocating between a closed state of being in close contact with a valve seat (12) and an open state of being separated from the valve seat (12). The valve casing (10) is a member including a valve cylinder (14). The valve seat (12) is fixed to the valve casing (10). The valve cylinder (14) is a member extending in a moving direction of the moving body (30) and is a member in which the moving body (30) moves. The primary flow path (40) is positioned on the upstream side relative to the valve cylinder (14) and uses a main axis direction being a straight line as an axis. The secondary flow path (50) is positioned on the downstream side relative to the valve cylinder (14) and uses the main axis direction as an axis. A flowing direction of a first main flow of a fluid passing through the inside of the valve cylinder (14) from the upstream side toward the downstream side has a larger component in the moving direction of the moving body (30) than a component in the main axis direction.

Description

non-return valve

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

[0002] Check valves for allowing fluid to pass in one direction through a pipe are 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 coaxially arranged. This check valve is called 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). Fluid pushes up the valve disc (16) and flows from the primary flow path to the secondary flow path. While the fluid flows from the primary flow path to the secondary flow path, the valve disc is maintained in an upwardly pressed state by the water flow of the fluid.

[0003] U.S. Pat. No. 1,703,248

[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.

[0006] The check valve of the present invention is a straight pipe fitting type oblique lift check valve through which a fluid flows from the upstream side to the downstream side, and is characterized in that it comprises a valve seat, a movable body that can move back and forth linearly 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 extends in the direction of movement of the movable body and includes a valve cylinder within which the movable body moves, a primary flow path that is located upstream of the valve cylinder and has its axis in the direction of the linear main axis, and a secondary flow path that is located downstream of the valve cylinder and has its axis in the direction of the main axis, and the flow direction of a first main stream of the fluid passing through the inside 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.

[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 that the first main flow mainly flows in a direction pushing up the valve body in the direction of movement (particularly toward the ceiling in the direction of movement).

[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 with the valve element in the direction pushing up the valve element, which makes it easier to maintain the state in which the valve element is pushed up.

[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] FIG. 4( a) is a perspective view showing an example of a check valve according to a first embodiment of the present invention. FIG. 4( b) is a longitudinal cross-sectional view taken along the main axis direction of a check valve according to a first embodiment in a closed state. FIG. 4( b) is a longitudinal cross-sectional view taken along the main axis direction of a check valve according to a first embodiment in an open state. FIG. 4( a) is a velocity distribution diagram when a fluid flows through a check valve according to the first embodiment. FIG. 4( b) is a diagram showing regions A to D in the same view as FIG. 4( a). FIG. 5( a) and FIG. 5( b) are velocity distribution diagrams when a fluid flows through a check valve according to the first embodiment. FIG. 4( a) is a rear view of a valve body in a check valve according to the first embodiment. The outline of the valve stem is indicated by a dotted line. FIG. 7( a) is a view of the lower end cylindrical portion according to the first embodiment as seen from the rear. FIG. 7( b) is a view of the lower end portion of the valve stem according to the first embodiment as seen from the rear. FIG. 8( a) is a partially exploded view of the valve disc according to the first embodiment as seen from the rear. FIG. 8( b) is a longitudinal cross-sectional view of the valve disc and the valve stem. FIG. 8( b) is a perspective view of a check valve according to a second embodiment of the present invention. FIG. 4( b) is a longitudinal cross-sectional view taken along the main axis direction of a check valve according to a second embodiment in a closed state. Fig. 13(a) and Fig. 13(b) are longitudinal sectional views along the main axis direction of a check valve in an open state according to a second embodiment. Fig. 13(a) and Fig. 13(b) are velocity distribution diagrams when a fluid flows in a check valve according to the second embodiment. Fig. 13(a) and Fig. 13(b) are rear views of a valve body in a check valve according to the second embodiment. The outline of a valve stem is shown by a dotted line.

[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] An embodiment of the present invention will be described below with reference to the drawings. In each drawing, corresponding components are designated by the same reference numerals, and redundant description will be omitted where appropriate. In this embodiment, the front-rear, left-right, up-down, and down-up directions will be 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 used for convenience to easily explain the relative relationships between the components, and does not limit the directions during manufacture or use of a 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 "plane" as used in this invention refers to a shape that is physically formed with a flat surface as the target, and naturally does not need to be a perfect geometric plane.

[0013] First Embodiment (Check Valve) Fig. 1 is a perspective view showing an example of a check valve 1 according to a first embodiment of the present invention. Fig. 2 is a vertical cross-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 movable body 30, a valve case 10, a primary flow path 40, and a secondary flow path 50. The movable body 30 is a member that can linearly reciprocate between a closed state in which it is in close contact with the valve seat 12 and an open state in which it is spaced apart from the valve seat 12. The valve case 10 is a member that includes a valve cylinder 14. The valve seat 12 is fixed to the valve case 10. The valve cylinder 14 is a member that extends in the movement direction of the movable body 30 and within which the movable body 30 moves. The primary flow path 40 is located upstream of the valve cylinder 14 and has an axis that is aligned with the linear main axis direction (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 main axis direction. As shown in FIGS. 4( a) and 4(b) , the flow direction of a first main flow of the fluid 200 passing through the valve cylinder 14 from upstream to downstream (the main flow of the fluid 200 shown in region A or region B in FIG. 4(b) ) has a larger component in the movement direction of the movable body 30 than in the main axis direction. By combining the shapes and arrangements of the various elements constituting the check valve 1, a first main flow in which the component in the movement direction of the movable body 30 is larger than in the main axis direction can be realized. A method for achieving this will be described in detail below. By having the flow direction of the first main flow, which is the main flow of the fluid 200 passing through the valve cylinder 14, have a larger component in the movement direction of the movable body 30 than in the main axis direction, the first main flow mainly flows in a direction pushing up the movable body 30 (the valve disc 32 described later) in the movement direction (particularly toward the ceiling in the movement direction). The first main flow mainly flows in the direction of movement, pushing up the valve element 32, and the fluid 200 continues to collide with the valve element 32 in the 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 unidirectionally from upstream to downstream, and is a component for preventing fluid from backflowing 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 a pipe connected downstream of the check valve 1 (downstream pipe) extends along the same line as the pipe connected upstream 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 the upstream pipe and the downstream pipe 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 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, as described below, the movable body 30 is seated on the valve seat 12, thereby narrowing the flow path of the fluid 200 and restricting the movement of the fluid 200. The open state of the check valve 1, as shown in FIG. 3, is a state in which the movement of the fluid 200 is less restricted than in the closed state of the check valve 1. Specifically, in the open state of the check valve 1, the valve seat 12 is separated from the movable body 30, creating a gap 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 stem 34. In other words, 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 when the check valve 1 is in the open state is smaller than the restriction on the movement of the fluid 200 when the check valve 1 is in the closed state.

[0016] FIG. 2 is a longitudinal 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 movable body 30. The housing is composed of a wall 19. Here, the wall 19 includes a piping wall 19a, a valve cylinder wall 19b, and a ceiling 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 the section through which the fluid 200 mainly flows from upstream to downstream. That is, the piping section 11 is the section connecting the inflow path (primary flow path 40) of the fluid to the outflow 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 line). Here, the axis connecting the center of the inlet 11a and the center of the outlet 11b (the axis indicated by a dashed line in FIG. 2 ) is referred to as the "main axis," and the extending 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 axial center. Flanges 17 protruding perpendicular to the main axis direction are provided at both ends of the piping section 11 in the main axis direction. The valve cylinder 14 is a part of the valve box 10 that houses the movable body 30. The valve cylinder 14 extends in the movement direction of the movable body 30 (a diagonal direction connecting the upper left and lower right in FIG. 2 ). The valve cylinder 14 is formed by a wall section 19 (valve cylinder wall section 19b) arranged to surround the axis, with the movement direction of the movable body 30 as its axial center. More specifically, the valve cylinder 14 is formed by the valve cylinder wall section 19b arranged to surround the periphery of the valve stem. 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 an end portion 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 referred to as the top side. At the lower end of the valve cylinder 14, the internal space of the valve cylinder 14 is connected to the internal space of the piping portion 11. The lower end of the valve cylinder 14 is an end portion of the valve cylinder 14 that is on the lower side in the direction of movement. The lower side is also referred to as the bottom side. In this embodiment, the ceiling portion 15 also serves as a lid for the valve cylinder 14. In other words, by opening the ceiling portion 15, the internal space of the valve cylinder 14 can be connected to the outside.The ceiling portion 15 is fixed to the valve cylinder wall portion 19b by a fastener 15b so as not to open.

[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 protrusion 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 separate member from the valve box 10 (wall portion 19) and fixed to the valve box 10 by adhesive, welding, or other means, 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 portion 11 and is arranged all the way around in this circumferential direction. As a result, the valve seat 12 can come into contact with the entire periphery of the moving body (particularly the sealing portion 36), which will be described later. 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 moving body 30 is a member that can move in a predetermined movement direction. When the moving body 30 moves downward in the movement direction, it can contact the valve seat 12, and when it moves upward in the movement direction, it can separate 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 as viewed from the movement direction of the moving body 30) is larger than the inner diameter of the valve seat 12 (the maximum diameter as viewed from the movement direction of the moving body 30). As a result, when the moving body 30 contacts the valve seat 12 in the closed state of the check valve 1, the moving body 30 can contact the valve seat 12 over the entire periphery of the valve seat 12, so that the moving body 30 can 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 movable body 30 includes a valve element 32 and a valve shaft 34. The valve element 32 is a member supported by the valve seat 12 when the check valve 1 is in a 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 a closed state to an open state, or from an open state to a closed state. The valve shaft 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 shaft 34, and at least one end of the valve shaft 34 is inserted into the cylindrical portion 16, as described below. Therefore, when the valve shaft 34 moves or slides along the cylindrical portion 16, the valve element 32 can move in a predetermined moving direction. Alternatively, 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 positional relationship between the valve element 32 and the valve stem 34 is fixed. The valve element 32 is disposed midway along the length of the valve stem 34. In other words, the valve stem 34 extends from the valve element 32 in both directions of movement in any state 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, in a case where the valve shaft 34 is not fixed to the valve element 32, it is sufficient that the valve shaft 34 extends in both directions in the movement direction from the valve element 32 at least when the check valve 1 transitions from the closed state to the open state. In the closed state or the open state of the check valve 1, the valve shaft 34 may extend in both directions in the movement direction from the valve element 32, or may extend in only one direction in the movement direction from the valve element 32. 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 movable 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 be a cylindrical member disposed radially outward of the valve cylinder 14 relative to the valve element 32. The valve element 32 may move or slide along the valve shaft 34 inside the valve shaft 34.

[0020] In this embodiment, the valve element 32 is fixed to the valve stem 34 as described above. Specifically, as shown in FIG. 8( b), the valve element 32 is fixed to the valve stem 34 by a mating 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 portion of the valve element 32 (a first gripping portion 38 and a second gripping portion 39, which will be described later) is positioned between the mating screw 35 and the screw receiving portion 34d. The mating 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, allowing the screw receiving portion 34d and the mating screw 35 to grip the valve element 32.

[0021] 2, the ceiling portion 15 includes a ceiling cavity 15a capable of accommodating a portion (upper end 34b) of the valve stem 34. In this embodiment, a portion of the ceiling portion 15 protrudes upward in the direction of movement of the movable body 30, and the interior of this portion is hollow. Because the upper end 34b can be accommodated in the ceiling cavity 15a, the valve stem 34 can be positioned sufficiently high in the direction of movement of the movable 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 shaft 34 is also supported by a spring body 37, which will be described later. Specifically, the valve shaft 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 shaft 34, which spans the upper cylindrical end portion 16b and the valve disc 32, is held in an orientation that follows the direction of movement of the movable body 30. Specifically, the lower end portion 34a (the end portion of the valve shaft 34 facing the bottom surface of the check valve 1) and the upper end portion 34b (the end portion of the valve shaft 34 facing the top surface of the check valve 1) of the valve shaft 34 are inserted into the cylindrical portions 16 (the lower cylindrical end portion 16a and the upper cylindrical end portion 16b) fixed to the valve box 10. The lower end cylindrical 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 the 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 the ring portion 18c in the center of the pipe portion 11. The ring portion 18c and each support portion 18 are integrally formed.Furthermore, a portion of the lower tubular end portion 16a (see FIG. 2) is inserted into and connected to the ring portion 18c. In this embodiment, the lower end portion 34a is supported by two or more (four) support portions 18. The four support portions 18 are arranged in a plus (+) shape. As shown in FIG. 2, in this embodiment, each of the second support portions 18b protrudes from the top of the protruding portion 11e or the top of the second protruding portion 11f (described later). Furthermore, as shown in FIG. 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 is in communication with the ceiling cavity 15a. The internal space of the upper tubular end portion 16b is aligned with the ceiling cavity 15a in the direction of movement of the movable body 30. In this embodiment, the upper cylindrical end portion 16b is fitted 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. As shown in FIG. 2 , when the check valve 1 is in the closed state, the upper end portion 34b of the valve stem 34 is inserted into the upper cylindrical end portion 16b (particularly its lower end), and the lower end portion 34a of the valve stem 34 penetrates the lower cylindrical end portion 16a and the ring portion 18c. At this time, the lower end portion 34a of the valve stem 34 is close to the pipe wall portion 19a. In this embodiment, the separation distance between the lower end portion 34a and the pipe wall portion 19a (the distance between the lower end portion 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 portion 34b into the upper cylindrical end portion 16b (the length of the portion of the upper end portion 34b inserted into the upper cylindrical end portion 16b, the length in the movement direction of the movable body 30). When the check valve 1 is in the closed state, the valve stem 34 extends downward to a degree that brings it very close to the pipe wall portion 19a, so that when the check valve 1 is in the open state, the valve stem 34 can be inserted to a sufficient depth into the tubular lower end portion 16a. When the check valve 1 is in the closed state, the valve stem 34 is inserted to a sufficient depth into the tubular upper end portion 16b, so that the valve stem 34 is sufficiently supported by the tubular upper end portion 16b in the closed state. As shown in FIG. 3 , when the check valve 1 is in the open state, the upper end portion 34b of the valve stem 34 penetrates the tubular upper end portion 16b. Furthermore, the portion of the upper end portion 34b that protrudes upward from the tubular upper end portion 16b is disposed within the ceiling cavity 15a. Meanwhile, the lower end portion 34a of the valve stem 34 is inserted into the tubular lower end portion 16a (particularly its upper end portion). The insertion depth of the lower end 34a of the valve shaft 34 into the tubular lower end portion 16a in the open state (the length of the portion of the lower end 34a that is inserted into the tubular lower 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 in the closed state (see FIG. 2) of the check valve 1. This allows the lower end 34a of the valve shaft 34 to be sufficiently supported by the tubular lower 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 disposed on the top side of the valve cylinder 14 in the sealing portion 36. The second gripping portion 39 is a member that is disposed on the bottom 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. Meanwhile, 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 recessed upward in the movement direction of the movable body 30. Similarly, the center of the first gripping portion 38 has a recess 38a recessed 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 lower end cylindrical portion 16a can be accommodated inside the recesses 38a and 39a (see FIG. 8(b)). As shown in FIG. 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 hollow lower end hollow portion 39b is disposed between the valve stem 34 and the second gripping portion 39 in the radial direction of the valve cylinder 14. Furthermore, the wall of the first gripping portion 38 that defines the recess 38a is spaced apart from the wall of the second gripping portion 39 that defines the recess 39a, and a hollow portion, an inner valve body hollow portion 38b, is disposed between the first gripping portion 38 and the second gripping portion 39 in the radial direction of the valve cylinder 14. Because the lower end hollow portion 39b that opens downward is formed at the bottom of the valve body 32, a portion of the fluid 200 that flows in from upstream can remain inside or near the lower end hollow portion 39b. Therefore, when the check valve 1 is in the open state, the valve opening degree is easily maintained.

[0025] As shown in FIG. 2 , in this embodiment, the surface of the valve element 32 facing the upstream side (the lower surface 39 d 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 upstream. In this embodiment, the radius of curvature of the lower surface 39 d 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 39 d (a portion of the lower surface 39 d from the center of the lower surface 39 d to the upstream end of the lower surface 39 d) 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 portion of the lower surface 39 d when viewed in the left-right direction may be the extension direction of a line connecting the center of the lower surface 39 d when viewed in the left-right direction to the upstream end of the lower surface 39 d. Because the lower surface 39d of the valve element 32 is a convex surface, the flow direction of the first main flow can be changed with less pressure loss, compared to when the lower surface 39d is a flat surface along the radial direction of the valve cylinder 14, even when the first main flow flows in the direction of movement of the movable body 30, as described below. In this embodiment, as shown in FIG. 8A , the second gripping portion 39 is formed to include a hollow portion 39c. Specifically, multiple hollow portions 39c are arranged in a row surrounding the valve stem 34. The hollow portions 39c are separated from each other by a partition extending in the direction of movement of the movable body 30. This partition makes 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, a single hollow portion 39c extending in the circumferential direction of the valve cylinder 14 may be arranged inside the second gripping portion 39.

[0026] As shown in FIGS. 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 end of the metal wire constituting the coil spring extends on a plane extending radially of the valve cylinder 14. In other words, the end of the metal wire constituting the coil spring extends along the circumferential direction of the valve shaft 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 urge the ceiling portion 15 and the valve body 32 straight 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 movement direction of the movable body 30. Therefore, when the check valve 1 is in the open state, the spring body 37 urges the valve body 32 downward in the movement direction of the movable body 30, and the spring body 37 urges the valve body 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 body 32 downward in the movement direction of the movable body 30. Therefore, when the check valve 1 is in the closed state, the valve body 32 is in pressure contact with the valve seat 12.

[0027] Next, the flow of the fluid 200 as it passes through the check valve 1 of this embodiment will be described. FIG. 4A is a velocity distribution diagram showing the distribution of the velocity of the fluid 200 when the check valve 1 is installed midway through a pipe and the fluid 200 flows into the pipe upstream of the check valve 1 at a flow velocity of 4.0 m / s. The lines in the fluid 200 indicate the direction of flow of the fluid 200. The velocity distribution diagrams in FIGS. 4A and 4B 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 pipes 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 disc 32 (corresponding to the valve opening described below) was fixed and that the fluid 200 was flowing at a mass flow rate corresponding to a predetermined flow velocity. The same applies to the above-mentioned simulations in FIGS. 5( a), 5(b), 12, 13(a), and 13(b). 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 element 32. A valve opening of 0% is defined as a state in which the valve element 32 is seated on the valve seat 12, and a valve opening of 100% is defined as a state in which the lower end of the valve element 32 (the lower left portion of the valve element 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 a valve opening of 0%, the fluid 200 does not substantially move from the primary flow path 40 to the secondary flow path 50. Furthermore, at a valve opening of 100%, the valve element 32 does not substantially impede the movement of the fluid 200 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 as 0 to 100%, based on the position of the valve disc 32 at 0% valve opening and the position of the valve disc 32 at 100% valve opening. However, in this embodiment, the valve opening is 80% when the valve disc 32 is in its uppermost position. In other words, in the check valve 1 of this embodiment, the lower end of the valve disc 32 does not rise to a position flush with the upper surface of the piping section 11 in the vertical direction, the maximum valve opening is 80%, and the valve opening does not take a value greater than 80%.Specifically, when the valve body 32 moves upward in the direction of movement of the movable body 30 to a position where the valve is open to 80%, the upper end 34b of the valve shaft 34 abuts against the ceiling portion 15 (more specifically, the upper surface that defines the ceiling cavity portion 15a), and therefore the valve shaft 34 and the valve body 32 cannot move to a position above the 80% valve opening position.

[0028] When the check valve 1 is in an open state, the fluid 200 mainly flows through the piping section 11 from the primary flow path 40 toward the secondary flow path 50. More specifically, the fluid 200 flows from the primary flow path 40 into the valve cylinder 14 and flows out from 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 interior of the valve cylinder 14 from the upstream side (primary flow path 40) to the downstream side (secondary flow path 50) has a greater component in the direction of movement of the moving body 30 than in the main axis direction. 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 from the primary flow path 40 into the valve cylinder 14 and attempts to flow out to the secondary flow path 50. In other words, the portion of the fluid 200 that flows from the primary flow path 40 into the valve cylinder 14 and flows out to the secondary flow path 50 without flowing back is the first main flow. In other words, the fluid 200 that flows from the primary flow path 40 into the valve cylinder 14 but flows from the secondary flow path 50 toward the primary flow path 40 in the main axial direction is not included in the first main flow. Specifically, a portion of the fluid 200 flowing inside the valve cylinder 14 below the valve disc 32 in the movement direction of the movable body 30 (a portion of the fluid 200 indicated by region A in FIG. 4B ) can become the first main flow. In this embodiment, in region A in FIG. 4B , a portion of the fluid 200 upstream (to the right) of the valve stem 34 has a spiral flow direction. On the other hand, in region A in FIG. 4B , a portion of the fluid 200 downstream (to the left) of the valve stem 34 (a portion of the fluid 200 indicated by region B in FIG. 4B ) 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 indicated by 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. 4A ). Thereafter, the first main flow flows out from between the valve disc 32 and the valve seat 12 into the secondary flow path 50.

[0029] 5( a ) and 5 ( b ) are longitudinal cross-sectional views of the check valve 1 installed midway through a pipe, showing the velocity distribution of the 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 approximately 50%, and the valve opening in FIG. 5( b ) is approximately 70%. In this embodiment, the greater the valve opening, the greater the component in the direction of movement of the movable body 30 in the flow direction of the first mainstream. 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 movable body 30 in the flow direction of the first mainstream. The greater the valve opening, the more compressed the spring body 37 is, and a greater upward force must be applied to the valve disc 32 in order to maintain the valve disc 32 in an open state. As described above, when the valve opening is large, the flow direction of the first main flow has a large movement direction component, which makes 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 larger main axis component, which makes it easier for the fluid 200 to flow smoothly from upstream to downstream, compared to when the valve opening is large. 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 flow is stably larger than the main axis 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 flow is more stably larger than the main axis 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 flow is more stably larger than the main axis component.

[0030] In this embodiment, the check valve 1 includes a flow direction guiding means for guiding the fluid 200 to flow in the movement direction of the movable body 30, thereby realizing the flow direction of the first mainstream having a greater component in the movement direction of the movable body 30 than in the main axis direction. The flow direction guiding means in this embodiment has a predetermined structure. For example, the flow direction of the first mainstream described above is realized by including at least a portion, preferably at least two or more, and more preferably at least three or more of the following structures. However, as exemplified by the structure of Patent Document 1 described below, even if at least a portion of the following structures is included, the flow direction of the first mainstream described above may not be realized if a structure that obstructs the first mainstream from flowing in the movement direction of the movable body 30 is included. 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 into the valve cylinder 14 from the primary flow path 40 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 shaft 34 extends from the valve element 32 to the lower end tubular portion 16a and the ring portion 18c in the movement direction of the movable body 30. This makes it easier for the flow direction of the fluid 200 to be aligned with the valve shaft 34, regardless of the valve opening degree. Secondly, in this embodiment, when the check valve 1 is in the closed state, the lower end 34a of the valve shaft 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 shaft 34 is located upstream of the ring portion 18c in the main axis direction. This makes it possible to encourage the flow direction of the fluid 200 flowing from upstream to be redirected to the movement direction of the movable body 30. In particular, in this embodiment, when the check valve 1 is in the closed state, the lowermost end of the valve shaft 34 is located vertically below the apex of the protruding portion 11e. Furthermore, in this embodiment, as will be described in detail later, the closer the lower end 34a of the valve shaft 34 is to the bottom surface of the pipe wall portion 19a, the longer the lower end 34a of the valve shaft 34 extends downward in the movement direction from the ring portion 18c. With this structure, the flow direction of the fluid 200 can be more effectively redirected to the direction along the movement direction of the movable body 30.Third, in this embodiment, as described below, 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 moving direction component, which changes the flow direction of the fluid 200 that passes near the support portion 18, allowing the fluid 200 to 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 of the lower end tubular portion 16a or the ring portion 18c. 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. In other words, 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. In other words, the flow direction of the fluid 200 flowing in the main axis direction is changed more abruptly than 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 redirected toward a direction having a component in the direction of movement of the large moving body 30. Fifth, as described below, the longitudinal direction of one support portion 18 (particularly the support portion 18 of the second support portion 18b located below the valve stem 34) is slightly inclined relative to the radial direction of the valve cylinder 14. Specifically, the support portion 18 is inclined downward in the direction of movement of the moving body 30 toward the center of the valve cylinder 14. As a result, a portion of the fluid 200 closer to the center in the main axis direction (a portion of the fluid 200 with a higher flow velocity) contacts the second support portion 18b first. Therefore, the flow direction of the fluid 200 can be more effectively redirected toward a direction having a component in the direction of movement 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 movement direction of the movable body 30 may be disposed within the valve cylinder 14, and 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.Alternatively, 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. Note that in the check valve of Patent Document 1, whether the valve opening is small or large, the flow direction of the first main flow does not have a larger component in the direction of movement of the moving body (disk (16)) than the main axial direction. Specifically, it is clearly stated that in the check valve of Patent Document 1, 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 element (disk (16)) is not fixed to the valve shaft (stem (17)), and in the closed state, the valve element is located at the lowest end of the valve shaft. Therefore, in the closed state, the valve shaft does not extend downward from the valve element. The check valve in Patent Document 1 also lacks 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)). This causes fluid that strikes the vanes (21) to be 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 body (disk (16)). As a result, in Patent Document 1, the first main flow flows linearly from upstream to downstream, as described in the same 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 flow has a large component in the direction of movement of the movable body 30. In this embodiment, the first main flow flows near the main axis. Specifically, as shown in FIGS. 4( a) and 4(b), when the valve opening is 30% or more, the first main flow flows across the main axis (the axis indicated by the dashed line in FIG. 4(a)). This can be achieved by positioning the lower end of the valve cylinder 14 (which is also the apex of the protruding portion 11e) closer to the bottom in the vertical direction than the main axis, and positioning the valve element 32 closer to the top in the vertical direction than the main axis. By having the first main flow flow near the main axis, pressure loss before and after flowing through the check valve 1 is small.

[0032] Furthermore, in the present 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 passage 50 than the portion of the first main flow that is close to the valve stem 34 (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 passage 50 than the portion of the first main flow that is close to the valve stem 34 (the downstream (left) region of region B). Furthermore, in the present embodiment, the flow velocity of 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) is smaller than the flow velocity of the fluid 200 in a portion of the first main flow that is closer to the secondary flow passage 50 than the portion of the first main flow that is close to the valve stem 34 (the left half of region B). That is, the flow velocity is relatively slow in a portion of the fluid 200 on the valve stem 34 side, particularly in the direction of movement of the movable body 30, and is relatively fast in a portion of the fluid 200 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 makes it possible to reduce 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 at a position 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. 5A , the second main flow of the fluid flowing out of the valve cylinder 14 into the secondary flow passage 50 (the main flow of the fluid 200 in region C in FIG. 5A ) flows in a direction obliquely inclined 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 passage, thereby suppressing turbulence near the downward slope (fluid flow that bounces off the downward slope). The second main flow refers to a major portion of the fluid 200 flowing out of the valve cylinder 14 into the secondary flow passage 50. In this embodiment, the flow direction of the second main flow has a main axis component and a vertical component. In this embodiment, the flow direction of the second main flow has a main axis 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 top side (upper side) of the valve box 10, where the valve sleeve 14 is located, to the bottom side (lower side), which is opposite the top side, based on the main axis direction. In other words, the vertical direction corresponds to the up-down direction in this embodiment. In this embodiment, the flow velocity in the lower flow area of ​​the second main flow, which is closer to the bottom side than the center in the vertical direction, is higher than the flow velocity in the upper flow area, which is closer to the top side than the center. As a result, even if the direction of the fluid flowing out of the valve sleeve (the flow direction of the second main flow) is obliquely downward as described above, the higher 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) of the valve box 10, as described below, or by other structures. For example, the above-mentioned flow velocity distribution may be achieved by the position of the valve stem 34 or the lower end cylindrical 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, 6.5 m / s or higher) 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 a 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 in the vertical direction than the main axis of the piping portion 11. 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 located closer to the top surface in the vertical direction (upward in the vertical direction) than the protruding portion 11e. In other words, this portion is located higher than the lower end of the valve seat 12 (a lower portion of the ring-shaped valve seat in the vertical 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 located inside the annular valve seat 12. This reduces the likelihood of this portion 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. That is, 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, thereby increasing the inner diameter of the valve seat 12 and enabling smoother movement of the fluid 200. Here, when 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 highest part of the upward slope 11c, which is also the most downstream part of the upward slope 11c). Furthermore, in this embodiment, the starting point of the upward slope 11c is located downstream in the axial direction of at least a portion of the valve box 10 that supports the lower end 34a of the valve stem 34 (the ring portion 18c or the tubular lower end portion 16a). This prevents the movement of the fluid 200 guided upward in the direction of movement of the movable body 30 by the upward slope 11c from being impeded by the ring portion 18c or the tubular lower end portion 16a. Furthermore, 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 in the axial direction of the tubular lower end portion 16a. More specifically, the apex of the protruding portion 11e is located downstream in the axial direction of the tubular lower end portion 16a. This prevents the movement of the fluid 200 guided upward in the direction of movement of the movable body 30 by the upward slope 11c from being impeded by the tubular lower end portion 16a.

[0038] As shown in FIG. 2 , in this embodiment, the upper surface (vertical wall 19) 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 a slope 11g that slopes downward from upstream to downstream. In this embodiment, the extension direction of the slope 11g, when viewed in the width direction of the check valve 1, includes a major axis direction component that is larger than the vertical direction component. Because the slope 11g extends along the major axis in this manner, 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 the present embodiment, the apex of the second protruding portion 11f (the portion of the second protruding portion 11f that protrudes most downward) is located upstream in the main axis direction of at least a portion of the valve box 10 that supports the lower end 34a of the valve stem 34 (the ring portion 18c or the tubular lower end portion 16a). In addition, in the present embodiment, the apex of the second protruding portion 11f is located closer to the ceiling in the vertical direction than the portion of the valve box 10 that supports the lower end 34a of the valve stem 34 (the ring portion 18c or the tubular lower end portion 16a). More specifically, the apex of the second protruding portion 11f is located closer to the ceiling in the vertical direction than the entire ring portion 18c and the entire tubular lower end portion 16a.

[0039] As described above, the lower end of the valve shaft 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 from the ring portion 18c along the radial direction of the valve cylinder 14 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 bottom side of the check valve 1 in the movement direction of the movable body 30 (toward the lower right in the figure) toward the lower end 34a of the valve shaft 34 with respect 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 extends in the vertical direction" means that the extension direction of the second support portion 18b has a vertical component. "The second support portion 18b is inclined toward the bottom surface of the check valve 1 in the movement direction of the movable body 30 toward the lower end 34a of the valve stem 34 with respect to the radial direction of the valve cylinder 14" means that the second support portion 18b extends in a direction inclined with respect to the radial direction of the valve cylinder 14 and is inclined with respect to the radial direction so as to approach the lower side in the movement direction of the movable body 30 as the second support portion 18b approaches the lower end 34a. This configuration securely holds the valve stem 34 while preventing the fluid 200 from colliding with the valve stem 34 or the valve disc 32, etc., and damaging the valve stem 34 or the valve disc 32, etc. Specifically, first, the first support portion 18a extending in the horizontal direction is perpendicular to the valve stem 34, thereby allowing the support portion 18 to fully perform its function of securely supporting the lower end 34a of the valve stem 34. Furthermore, since one end of the second support portion 18b, which is positioned toward the center of the flow path, is positioned protruding upstream, the second support portion 18b causes the fluid 200 in the center of the flow path, which has the fastest flow, to slow down when it hits one end of the second support portion 18b, thereby preventing 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 a longitudinal direction and a 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 FIG. 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 aligned with the main axis direction (front-rear direction). Furthermore, the width direction of the second support portion 18b is aligned with the movement direction. Here, the width direction of the support portion 18 aligned with the 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 greater 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 impeded by the support portion 18.

[0042] In this embodiment, as shown in FIG. 7A , a groove 16d extending in the movement direction of the movable body 30 (the vertical direction in the drawing) may be formed in a portion of the inner wall (the cylindrical inner wall 16c) of the cylindrical portion 16 (the lower end cylindrical portion 16a) on the bottom side of the check valve 1 (a region of the cylindrical inner wall 16c facing the top surface). Such a 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 the cylindrical inner wall 16c may have one groove 16d or three or more grooves 16d. Furthermore, in this embodiment, the groove 16d is formed only in a portion of the lower end of the cylindrical inner wall 16c, and is not formed in a portion of the upper end of the cylindrical inner wall 16c. Alternatively, the groove 16d may extend from the upper end to the lower end of the cylindrical inner wall 16c. In this embodiment, as shown in FIG. 7B , a groove 34c extending in the movement direction of the movable body 30 (the up-down direction in the figure) is formed on the surface (outer peripheral surface) of the lower end portion 34a. Both the groove 16d in the cylindrical portion inner wall 16c and the groove 34c in the surface of the lower end portion 34a may be formed, or the groove 16d may not be formed on the cylindrical portion inner wall 16c and the groove 34c may be formed on the surface of the lower end portion 34a. In this embodiment, the groove 34c is formed only on a portion of the lower end side of the surface of the lower end portion 34a and not on a portion of the upper end side of the surface. Similar to the groove 16d in the lower end cylindrical portion 16a, a groove (not shown) extending in the movement direction of the movable body 30 may be formed on a portion of the inner wall of the upper end cylindrical portion 16b on the bottom side of the check valve 1. Similar to the groove 34c on the surface of the lower end 34a, a groove (not shown) extending in the direction of movement of the moving body 30 may also be formed on the surface (outer peripheral surface) of the upper end 34b of the valve shaft 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). The sealing portion 36 has a sealing recess 36a formed therein, and the sealing recess 36a is formed deep in part on the bottom side, which effectively prevents the sealing portion 36 and the second gripping portion 39 from being displaced by the fluid 200 flowing out at a high speed from the valve cylinder 14. In this embodiment, the sealing recess 36a is formed so as to surround the periphery of the valve shaft 34 when viewed in the direction of movement of the movable body 30. Alternatively, the sealing recess 36a may be formed only in an area below (on the bottom side of) the lower surface 36b when viewed in the direction of movement of the movable body 30.

[0044] Second Embodiment Fig. 9 is a perspective view showing an example of a check valve 1 according to this embodiment. Figs. 12 to 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 flows 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 according to 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 indicated by region B in Fig. 12 ) has a larger component in the direction of movement of the movable 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 box 10 that supports the lower end 34a of the valve stem 34.

[0046] In this embodiment, the check valve 1 has the following particular structure, so that the flow direction of the first mainstream of the fluid 200 has a greater component in the direction of movement of the movable 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 direction of movement 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 beyond the ring portion 18c in the direction of movement of the movable body 30. Furthermore, the width direction of one support portion 18 (particularly the support portion 18e arranged below the valve stem 34) has a component in the direction of movement. Furthermore, the starting point of the upward slope 11c is located downstream of the lowest end of the lower end tubular portion 16a or the ring portion 18c.

[0047] First, in this embodiment, as shown in Figures 10 and 14, the lower tubular end portion 16a is supported by two support portions 18. Specifically, 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 lower tubular end portion 16a. In this embodiment, no support portions 18 are provided on either side of the ring portion 18c in the width direction (left-right direction) of the check valve 1, allowing fluid 200 to 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. Furthermore, the lower support portion 18e protrudes from the middle of the upslope 11c in the main axis 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 top of the protruding portion 11e toward the ring portion 18c.

[0048] As shown in Figures 10 and 11, the upper support portion 18d and the lower support portion 18e have a plate shape, similar to the first embodiment. 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 movable 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 relative 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 movable 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 portion of the bottom surface of the valve seat 12 in the vertical direction) is not located below a portion of the valve box 10 (such as the ring portion 18c) 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 portion 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 of this embodiment has the following features, similar to those of the first embodiment. The second main flow of the fluid 200 flowing from the valve cylinder 14 to the secondary flow path 50 flows in a direction obliquely inclined toward the bottom surface of the check valve 1 with respect to the main axis direction. In the second main flow, the flow velocity in the lower flow area located closer to the bottom surface than the vertical center is greater than the flow velocity in the upper flow area located closer to the top surface than the vertical center. Furthermore, both ends (upper end 34b and lower end 34a) of the valve stem 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 movement direction of the movable body 30. Furthermore, a groove 16d extending in the movement direction of the movable body 30 is formed in a portion of the inner wall of the lower end tubular 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 embodiments encompass the following technical concepts: (1) A straight pipe fitting type oblique lift check valve through which a fluid flows from an upstream side to a downstream side, the check valve comprising: a valve seat; a movable body that is linearly movable 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, the valve seat being fixed and including a valve cylinder that extends in the direction of movement of the movable body and within which the movable body moves; a primary flow path that is located upstream of the valve cylinder and has its axis in the direction of a linear main axis; and a secondary flow path that is located downstream of the valve cylinder and has its axis in the direction of the main axis, wherein the flow direction of a first main flow of the fluid passing through the valve cylinder from the upstream side to the downstream side has a larger component in the direction of movement of the movable body than a component in the direction of the main axis. (1-1) The check valve according to (1), wherein the flow direction of a portion of the first main flow that is closer to the valve stem has a larger component in the movement direction than the flow direction of another portion of the first main flow that is closer to the secondary flow path than the first portion. (1-2) The check valve according to (1-1), wherein the flow velocity of the portion of the first main flow that is closer to the valve stem is lower than the flow velocity of the other portion of the first main flow that is closer to the secondary flow path 50 than the portion of the first main flow. (2) The check valve according to (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 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 component of the second main flow in a direction connecting the top surface side and the bottom surface side of the check valve increases as the valve opening degree decreases. (3) The check valve according to (2), wherein the second main flow has a width in a vertical direction from a top side, which is a side of the valve body 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, and a flow velocity in a lower flow area, which is closer to the bottom side than to a center of the second main flow in the vertical direction, is greater than a flow velocity in an upper flow area, which is closer to the top side than to the center. (4) The check valve according to any one of (1) to (3), wherein the movable body includes a valve disc supported by the valve seat in the closed state and a valve stem extending in both directions of the moving direction from the valve disc, and both ends of the valve stem are supported by a wall portion of the valve body.(5) A check valve according to (4), wherein a lower end portion of the valve shaft, which is the end portion on the bottom side of the check valve, is supported by two or more support portions that protrude from the wall portion of the valve box and extend toward the lower end portion, a first support portion extends along the width direction of the check valve and is perpendicular to the moving direction, and a second support portion extends along a vertical direction from the main axis direction toward the top side, which is the side of the valve box where the valve cylinder is provided, to the bottom side, which is the opposite side to the top side, and is inclined toward the lower end portion toward the bottom side of the check valve in the moving direction with respect to the direction perpendicular to the moving direction. (6) The check valve according to (5), wherein the support portion has a plate shape and extends in a longitudinal direction extending from the wall portion to the lower end portion, a plate thickness direction, and a width direction perpendicular to the longitudinal direction, wherein the width direction of the first support portion is along the main axis direction, and the width direction of the second support portion is along 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 check valve according to any one of (4) to (6), wherein a lower end portion of the valve stem, which is the end portion on the bottom side of the check valve, is inserted into a cylindrical portion fixed to the wall portion of the valve body, and a groove portion 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 portion extending in the movement direction of the moving body is formed on the outer peripheral surface of the lower end portion. (8) The check valve according to any one of (4) to (7), wherein the valve body includes: a sealing portion that is in close contact with the valve seat in the closed state; a first gripping portion that is arranged on the top side of the valve cylinder in the sealing portion; and a second gripping portion that is arranged on the bottom 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 that is recessed more toward the inside of the sealing portion than the outer periphery of the bottom surface of the sealing portion is formed in the center of the bottom surface of the sealing portion facing the bottom side of the check valve; and a depth dimension of a portion of the sealing recess on the bottom surface side is larger than a depth dimension of another portion.(9) The check valve according to any one of (4) to (8), wherein an upper end of the valve stem, which is an end on a top surface side of the check valve, is inserted into a cylindrical upper end portion fixed to the ceiling portion of the valve body, and wherein, in a closed state of the check valve, a distance in the movement direction between a lower end of the valve stem and a pipe wall portion that defines a pipe portion extending in the main axis direction is smaller than an insertion depth of the upper end of the valve stem into the cylindrical upper end portion. (10) The check valve according to any one of (4) to (9), wherein, in an open state of the check valve, an insertion depth of the lower end of the valve stem into the cylindrical lower end portion is greater than a distance between the lower end of the valve stem and a pipe wall portion that defines the pipe portion extending in the main axis direction in the closed state of the check valve. (11) The check valve according to any one of (1) to (10), wherein, as the valve opening degree increases, the flow direction of the first main current has a greater component in the movement direction of the moving body. (12) The check valve according to any one of (1) to (11), wherein the flow direction of the first main current has a greater component in the direction of movement of the moving body as the flow velocity of the fluid flowing into the check valve increases. (13) The check valve according to any one of (4) to (10), which relies on (3), wherein the valve box has a piping portion extending in the main axis direction, wherein a bottom surface of the piping portion includes a protruding portion protruding toward a ceiling surface in the vertical direction, and a portion of the valve box that supports a lower end of the valve stem is located closer to the ceiling surface in the vertical direction than the protruding portion. (14) The check valve according to any one of (4) to (10), wherein the valve box has a piping portion extending in the main axis direction, wherein a bottom surface of the piping portion includes an upslope that slopes upward from the upstream side to the downstream side toward the ceiling surface in the vertical direction, and a starting point of the upslope is located downstream in the main axis direction of at least a portion of a portion of the valve box that supports a 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 check valve according to any one of (4) to (10), wherein the valve body has a piping portion extending in the main axis direction, a portion of the piping portion on the top surface side that defines the primary flow path 40 includes a second protruding portion that protrudes toward the bottom surface side in the vertical direction, and the apex of the second protruding portion is located upstream of at least a portion of a portion of the valve body that supports the lower end of the valve stem in the main axis direction.(17) The check valve according to (1), wherein the valve stem extends from the valve body toward the bottom side of the check valve in the movement direction. (18) The check valve according to (1) or (17), wherein, when the check valve is in a closed state, the lower end of the valve stem protrudes downward beyond the ring portion in the movement direction of the movable body. (19) The check valve according to any one of (1), (17), or (18), wherein the width direction of one support portion has a component in the movement direction. (20) The check valve according to any one of (1), (17), (18), or (19), wherein the starting point of the upward slope in the pipe wall portion is located at one end of the downstream side of the lower end tubular portion or downstream of the ring portion. (21) The check valve according to 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 movement direction of the movable body. (22) The check valve according to (4), wherein the valve stem extends from the valve body toward the bottom side of the check valve in the movement direction, and when the check valve is in a closed state, the lower end of the valve stem protrudes downwardly beyond the ring portion in the movement direction of the movable body, and the starting point of the upward slope of the pipe wall portion is located at one downstream end of the lower cylindrical end portion or downstream of the ring portion. (23) The check valve according to (4), wherein the width direction of one support portion has a component in the movement direction, and 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 movement direction of the movable body. (24) The check valve according to (4), wherein the valve stem extends from the valve body toward the bottom side of the check valve in the movement direction, and the starting point of the upward slope of the pipe wall portion is located at one downstream end of the lower cylindrical end portion or downstream of the ring portion. (25) The check valve according to (4), wherein the valve stem extends from the valve body toward the bottom side of the check valve in the movement direction, and when the check valve is in a closed state, the lower end of the valve stem protrudes below the ring portion in the movement direction of the movable body. (26) The check valve according to (4), wherein the valve stem extends from the valve body toward the bottom side of the check valve in the movement direction, and when the check valve is in a closed state, the lower end of the valve stem protrudes below the ring portion in the movement direction of the movable body, and 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 movement direction of the movable body.

[0054] DESCRIPTION OF SYMBOLS 1 Check valve 10 Valve box 11 Piping section 11a Inlet 11b Outlet 11c Upward slope 11d Downward slope 11e Projecting section 11f Second projecting section 11g Slope 12 Valve seat 14 Valve cylinder 15 Ceiling section 15a Ceiling cavity section 15b Fastener 16 Cylinder section 16a Lower end cylinder section 16b Upper end cylinder section 16c Cylinder section inner wall 16d Groove section 17 Flange section 18 Support section 18a First support section 18b Second support section 18c Ring section 18d Upper support section 18e Lower support section 19 Wall section 19a Piping wall section 19b Valve cylinder wall section 30 Moving body 32 Valve element 34 Valve stem 34a Lower end 34b Upper end 34c Groove 34d Screw receiving portion 35 Threaded screw 36 Sealing portion 36a Sealing recess 36b Lower surface 37 Spring body 38 First gripping portion 38a Recess 38b Valve body inner hollow portion 39 Second gripping portion 39a Recess 39b Lower end hollow portion 39c Hollow portion 40 Primary flow path 50 Secondary flow path 200 Fluid

Claims

1. A straight pipe fitting type oblique lift check valve through which a fluid flows from the upstream side to the downstream side, comprising: a valve seat; a movable body that can move back and forth linearly 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, extending in the direction of movement of the movable body and including a valve cylinder within which the movable body moves; a primary flow path that is located upstream of the valve cylinder and has its axis in the direction of the linear main axis; and a secondary flow path that is located downstream of the valve cylinder and has its axis in the direction of the main axis, wherein the flow direction of a first main flow of the fluid passing through 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 in the direction of the main axis.

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

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

4. A check valve as claimed in any one of claims 1 to 3, wherein the movable body includes a valve element supported on the valve seat in the closed state, and a valve stem extending from the valve element in both directions of the movement, both ends of the valve stem being supported by the wall of the valve box.

5. A check valve as described in claim 4, wherein the lower end of the valve shaft, which is the end on the bottom side of the check valve, is supported by two or more support parts that protrude from the wall part of the valve box and extend towards the lower end, wherein a first of the support parts extends along the width direction of the check valve and is perpendicular to the direction of movement, and wherein the second support part extends along a vertical direction from the main axis direction toward the top side of the valve box, which is the side on which the valve cylinder is provided, to the bottom side, which is the opposite side to the top side, and is inclined towards the lower end in a direction towards the bottom side of the check valve in the direction of movement with respect to the direction perpendicular to the direction of movement.

6. A check valve as described in claim 5, wherein the support portion has a plate shape and 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 being along the main axis direction, and the width direction of the second support portion being along the movement direction.

7. A check valve as claimed in any one of claims 4 to 6, wherein the lower end of the valve shaft, which is the end on the bottom side of the check valve, is inserted into a cylindrical portion fixed to the wall portion of the valve box, and a groove portion extending in the direction of movement is formed in a part of the inner wall of the cylindrical portion on the bottom side of the check valve.

8. A check valve as described in any one of claims 4 to 7, wherein the valve body includes a sealing portion that is in tight contact with the valve seat in the closed state, a first gripping portion that is arranged on the top side of the valve cylinder in the sealing portion, and a second gripping portion that is arranged on the bottom side of the check valve in the sealing portion, the sealing portion being sandwiched between the first gripping portion and the second gripping portion in the movement direction, a sealing recess that is recessed more inward than the outer periphery of the bottom surface of the sealing portion is formed in the central portion of the underside facing the bottom side of the check valve, and a depth dimension of a portion of the sealing recess on the bottom side is greater than the depth dimension of another portion.