Flow control valve

Abstract

Flow control valve (1) comprising: a valve seat (13) with a valve opening (16) and a seat surface (17) formed at an edge of the valve opening; a valve element (14) formed on an outer circumference with a sealing surface (18) corresponding to the seat surface (17); and a rotatable shaft (15) integrally provided with the valve element (14), wherein the rotatable shaft (15) has a central axis (Ls) arranged eccentrically from a central axis (Lh) of the valve opening (16) in a radial direction of the valve opening, and wherein the sealing surface (18) is arranged eccentrically from the central axis (Ls) of the rotatable shaft (15) in a direction of extension of a central axis (Lv) of the valve element (14), wherein the flow control valve (1) further comprises a part (51) restricting the direction of movement of the valve element, which is configured to prevent the rotation of the valve element (14).to stop the rotation of the valve element (14) about the central axis (Ls) of the rotatable shaft (15) together with the rotatable shaft (15), and then to rotate the valve element (14) about an eccentric axis (Le) arranged eccentrically from the central axis (Ls) of the rotatable shaft (15) relative to the rotatable shaft (15), which is rotatable about the central axis (Ls) of the rotatable shaft (15), so that the valve element (14) moves towards the valve seat (13), characterized in that the flow control valve (1) comprises: a stop (53) for defining a range of relative rotation of the valve element (14), which is configured to rotate about the eccentric axis (Le) with respect to the rotatable shaft (15); and a spring (54) provided between the rotatable shaft (15) and the valve element (14) to push the valve element (14) towards the stop (53).wherein the part (51) restricting the direction of movement of the valve element forms part of the valve seat (13) and has a lip section (52) which is designed to be pressed and bent by the valve element (14) when the valve element (14) moves towards the valve seat (13) and wherein a spring force generated in the lip section (52) when the lip section (52) is bent is greater than a compressive force of the spring (54) which pushes the valve element (14) towards the stop (53).

Description

Technical FieldThe present invention relates to a flow control valve accommodating a valve element having a rotation center (a rotatable shaft) disposed eccentrically from a center of a valve hole, and a sealing surface of the valve element disposed eccentrically from the rotatable shaft.Prior ArtPatent Document 1 discloses a butterfly valve configured such that rotation of a rotatable shaft causes rotation of an eccentric through 180 degrees, so that pressure is applied to a valve shaft by a coil spring to press a valve plate against a valve seat while the valve is closed from a fully open position.Patent documents 2 and 3 disclose a flow control valve having the features according to the preamble of claim 1.Prior Art DocumentsPatent DocumentsPatent Document 1: Japanese Utility Model Application Publication No. JP S50-23 733 UPatent Document 2: Publication of U.S. Patent Application: US 2018 / 0 274 683 A1Patent Document 3: German Patent Specification: DE 35 04 608 C2SUMMARY OF THE INVENTIONProblems to be Solved by the InventionHowever, in the butterfly valve disclosed in Patent Document 1, the valve plate is rotated and pressed against the valve seat, and this rotation of the valve plate on the valve seat and the vicinity thereof may lead to abrasion between the valve seat and the valve plate.The present invention has been made in view of the circumstances for solving the above problem, and has the purpose of providing a flow control valve that can restrict the occurrence of abrasion between the valve seat and the valve element caused by the rotation of the valve element on the valve seat and the vicinity thereof.Solution of the ProblemIn order to achieve the above object, an aspect of the invention provides a flow control valve (also referred to as a flow control valve) including: a valve seat having a valve hole and a seat surface formed on an edge of the valve hole; a valve element formed on an outer periphery with a sealing surface corresponding to the seat surface; A rotatable shaft integrally provided with the valve element, wherein the rotatable shaft has a central axis disposed eccentrically from a central axis of the valve hole in a radial direction of the valve hole, and wherein the sealing surface is disposed eccentrically from the central axis of the rotatable shaft toward an extending direction of a central axis of the valve element, wherein the flow control valve further comprises a valve element moving direction restricting part configured to stop rotation of the valve element rotatable together with the rotatable shaft about the central axis of the rotatable shaft, and thereafter to relatively rotate the valve element about an eccentric axis disposed eccentrically from the central axis of the rotatable shaft with respect to the rotatable shaft rotatable about the central axis of the rotatable shaft, so that the valve element moves toward the valve seat.According to the above aspect, while an open valve state is changed to a fully closed state, the valve element may move toward the valve seat after the valve element stops rotating. This achieves a limitation on the abrasion between the valve seat and the valve element caused by rotation of the valve element on the valve seat and its vicinity. Furthermore, the valve element is pressed firmly against the valve seat, whereby the sealing effect between the valve seat and the valve element is improved. Accordingly, a flow channel is securely sealed in the fully closed state.In the above aspect, the flow control valve preferably includes: a stopper for defining a range of relative rotation of the valve element configured to rotate about the eccentric axis with respect to the rotatable shaft; and a spring provided between the rotatable shaft and the valve element to urge the valve element toward the stopper, wherein the valve element movement direction restricting part constitutes a part of the valve seat and has a lip portion configured to be pressed and bent by the valve element when the valve element moves toward the valve seat, and wherein a spring force generated in the lip portion when the lip portion is bent is larger than a pressing force of the spring urging the valve element toward the stopper.According to the above aspect, the valve element can move toward the valve seat while maintaining its position. This improves the sealing effect between the valve seat and the valve element.Preferably, in the above aspect, at a rotation stop timing when the valve element moving direction restricting part stops the rotation of the valve element, the eccentric axis is disposed in a first position that is an opposite side to the valve seat with respect to a horizontal straight line extending through the central axis of the rotatable shaft and parallel to a radial direction of the valve element, and at a stopper contact timing after the rotation stop timing when the valve element moving direction restricting part brings the valve element toward the valve seat to bring the valve element into contact with the stopper, the eccentric axis is disposed in a second position on a side near the valve seat with respect to the horizontal straight line.According to the above aspect, the valve element can be further securely pressed against the valve seat, thereby further improving the sealing effect between the valve seat and the valve element.In the above aspect, preferably, the flow control valve includes a bearing for supporting the rotatable shaft, and the rotatable shaft has an allowable amount of movement of relative movement in the radial direction of the rotatable shaft with respect to the bearing, the allowable amount of movement being larger than an amount of movement of the rotatable shaft in the radial direction of the rotatable shaft when the eccentric axis moves between the first position and the second position.According to the above aspect, the rotatable shaft can move in the radial direction of the rotatable shaft without being restricted by the bearing. Thus, the movement of the rotatable shaft restricts the movement of the valve element, thus preventing the valve element from slipping with the valve seat.Preferably, in the above aspect, the stopper is a protrusion integrally formed with the rotatable shaft.According to the above aspect, the number of components decreases and a cost reduction is achieved.Preferably, in the above aspect, the valve element moving direction restricting part is a protruding part protruding from a valve seat side toward the valve element, and the protruding part includes a guide portion configured to be in contact with a distal end in a rotational direction of the valve element when the valve element that has rotated together with the rotatable shaft about the central axis of the rotatable shaft stops rotating, and configured to guide the valve element in its movement toward the valve seat while the valve element relatively rotates about the eccentric axis with respect to the rotatable shaft and moves toward the valve seat.According to the above aspect, the guide portion guides movement of the valve element, thereby restricting abrasion between the valve seat and the valve element caused by the rotation of the valve element on the valve seat and the vicinity thereof.Effects of the InventionA flow control valve according to the present invention can cause a restriction of abrasion between a valve seat and a valve element caused by rotation of the valve element on the valve seat and the vicinity thereof.Brief Description of the DrawingsFIG. 1 is a front view of a flow control valve of the present embodiment; FIG. 2 is a top view of the flow control valve of the present embodiment; FIG. 3 is a perspective view, partly in section, of a valve unit in a fully closed state; FIG. 4 is a perspective view, partly in section, of a valve unit in an open state; FIG. 5 is a side view of a valve seat, a valve element, and a rotatable shaft in the fully closed state; FIG. 6 is a sectional view taken along line A-A in FIG. 5 ; FIG. 7 is a sectional view taken along line B-B in FIG. 1 ; FIG. 8 is a sectional view taken along line C-C in FIG. 1 ; FIG. 9 is a sectional view taken along line D-D in FIG. 8; FIG. 10 is a schematic view showing the opened state at a cross-sectional position taken along the line E-E in FIG. 8 ; FIG. 11 is a schematic view showing a set state in the cross-sectional position along a line E-E in FIG. 8 ; FIG. 12 is a schematic view showing the fully closed state in the cross-sectional position along a line E-E in FIG. 8 ; FIG. 13 is an explanatory view showing a position of an eccentric axis in the set state and the fully closed state; FIG. 14 schematically shows a structural view of a fuel cell system; and FIG. 15 schematically shows a view of a fuel cell system according to an exemplary refinement.Embodiment of the InventionA detailed description of a preferred embodiment of a flow control valve 1 will be explained. As described below, the flow control valve 1 is configured as, for example, an integral valve 181 (see FIG. 14 ) in an air system 113 of a fuel cell system 101.As shown in FIGS. 1 and 2, the flow control valve 1 includes a valve unit 2 and a drive mechanism unit 3. the drive unit 2 includes a pipe portion 12 (see FIG. 7 ) provided with a flow passage 11 that allows a fluid to flow therethrough. In this flow passage 11, a valve seat 13, a valve element 14, and a rotatable shaft 15 (see FIG. 3 and others) are disposed. The drive mechanism unit 3 is provided with a motor 32 and a speed reducing device 33 (see FIG. 7 ). The drive mechanism unit 3 transmits a drive force from the motor 32 to the rotatable shaft 15.As shown in FIGS. 3 and 4, the flow passage 11 is formed with a stepped portion 10 in which the valve seat 13 is fixed by press-fitting. The valve seat 13 has an annular shape with a valve hole 16 at the center. At an edge of the valve opening 16, an annular seat surface 17 is formed. The valve element 14 has a round disk shape with an annular sealing surface 18 on an outer periphery of the valve element 14, wherein the sealing surface 18 corresponds to the seat surface 17. The valve element 14 is fixed to the rotatable shaft 15 and movable together with the rotatable shaft 15.As shown in FIGS. 5 and 6, a shaft axis Ls as a central axis of the rotatable shaft 15 extends parallel to a diameter direction of the valve element 14 (specifically, in a diameter direction of a circular disk-shaped part of the valve element 14) and is disposed eccentrically or offset from a central axis Lh of the valve hole 16 in a radial direction of the valve hole 16. The sealing surface 18 of the valve element 14 is arranged eccentrically from the shaft axis Ls in the direction of an extension direction of the center axis Lv of the valve element 14. The flow control valve 1 thus consists of a double eccentric valve.As shown in FIGS. 7 and 8, a valve housing 35 made of metal or synthetic resin is provided with the flow passage 11 and the pipe portion 12. An end frame 36 made of metal or synthetic resin closes an open end of the valve housing 35. The rotatable shaft 15 has a pin 15a at its distal end. More specifically, the pin 15 ais provided at one end of the rotatable shaft 15 (on a side near the valve element 14) in the direction of the shaft axis Ls. A diameter of the pin 15 ais smaller than a diameter of a portion of the rotatable shaft 15 other than the pin 15 a. At the other end of the rotatable shaft 15 (on a side near the main gear 41) in the shaft axis Ls direction, a proximal end portion 15 bis provided.The rotatable shaft 15 has a free end on the distal end side where the pin 15 ais provided so that the distal end is inserted and provided in the flow passage 11 of the tube portion 12. The rotatable shaft 15 is supported by a cantilever structure having a first bearing 37 and a second bearing 38 and rotatable with respect to the valve housing 35 through the first bearing 37 and the second bearing 38. The first bearing 37 and the second bearing 38 are each composed of a ball bearing. The first bearing 37 and the second bearing 38 are provided at respective locations between the valve element 14 and the main transmission 41 along the shaft axis Ls to rotatably support the rotatable shaft 15. The first bearing 37 is closer to the main gear 41 than the second bearing 38 The valve element 14 is fixed to the pin 15 aformed at the distal end of the rotatable shaft 15 and is disposed in the flow passage 11.As shown in FIGS. 7 and 8, the main gear 41 is fixed to the proximal end portion 15 bof the rotatable shaft 15. Between the valve housing 35 and the main transmission 41, a return spring 40 for generating a return spring force is provided. The return spring force is a force for rotating the rotatable shaft 15 in a valve closing direction and a force for pressing the valve element 14 in the valve closing direction. Further, the main gear 41 is integrally formed with the rotatable shaft 15 to receive the driving force generated in the motor 32.The motor 32 generates a driving force to rotate the rotatable shaft 15 about the shaft axis Ls. As shown in FIG. 7, the motor 32 is drivingly coupled to the rotatable shaft 15 via the speed reducer 33 to transmit the driving force to the rotatable shaft 15. More specifically, a motor gear 43 is fixed to the motor 32. In order to transmit the driving force, this motor transmission 43 is coupled to the main transmission 41 via an intermediate transmission 42.The intermediate gear 42 is rotatably supported by the valve housing 35 via a pin axis 44. The intermediate gear 42 is drivingly connected to the main gear 41 and the motor gear 43. The main transmission 41, the intermediate transmission 42, and the motor transmission 43 constituting the speed reduction device 33 are each made of resin.In the flow control valve 1 configured as above, the rotatable shaft 15 rotates about the shaft axis Ls when the driving force from the motor 32 is transmitted to the rotatable shaft 15 via the speed reducing device 33. This configuration brings the flow control valve 1 into the fully closed state in which the sealing surface 18 of the valve element 14 comes into contact with the seat surface 17 of the valve seat 13 (see FIG. 3 ) or into the open state (the fully open state) in which the sealing surface 18 of the valve element 14 is located farthest from the seat surface 17 (see FIG. 4 ).The flow control valve 1 of the present embodiment includes a lip seal 51 as shown in FIG. 6 and other figures. The lip seal 51 forms part of the valve seat 13 and includes a lip portion 52 formed with the seat surface 17, and as will be described later, this lip portion 52 is pressed and bent by the valve element 14 as the valve element 14 moves toward the valve seat 13. The lip seal 51 corresponds to an example of "a valve element moving direction restricting part" according to the present invention.The valve element 14 can rotate relative to the rotatable shaft 15 about an eccentric axis Le (see FIG. 6 and others) provided as a center axis of the pin 15 aexpectrophotometrically of the shaft axis Ls. The rotatable shaft 15 is provided, as shown in FIG. 9, with a stopper 53 which is a protrusion integrally formed with the rotatable shaft 15 and which protrudes toward the pin 15 afrom a columnar portion of the rotatable shaft 15 supported by the first bearing 37 and the second bearing 38. The stopper 53 has a first side 61 and a second side 62 configured to face the valve element 14. The stopper 53 defines an allowable range of relative rotation of the valve element 14 about the eccentric axis Le with respect to the rotatable shaft 15. In other words, the valve element 14 can relatively rotate about the eccentric axis Le with respect to the rotatable shaft 15 in a range between a position in which the valve element 14 comes into contact with the first side 61 of the stopper 53 and a position in which the valve element 14 comes into contact with the second side 62 of the stopper 53. FIG. 9 shows a state in which the valve element 14 is in contact with the second side 62 of the stopper 53.As shown in FIGS. 5 and 6, the flow control valve 1 includes a spring 54 as a coil spring made of wire wound spirally. The spring 54 is provided between the valve element 14 and the rotatable shaft 15. More specifically, one end portion of the wire constituting the spring 54 is connected to the valve member 14 and the other end portion of the wire constituting the spring 54 is connected to the rotatable shaft 15. The spring 54 urges the valve element 14 toward the stopper 53.In the flow control valve 1 having the above configuration of the present embodiment, the operation of the valve during the change from the open to the fully closed state will be described below.In the opened state, the valve element 14 is urged toward the first side 61 of the stopper 53 of the rotatable shaft 15 by a urging force Fs of the spring 54 as shown in FIG. 10. Thus, an end face 14 aof the valve element 14 is in contact with the first side 61 of the stopper 53. As shown in FIG. 10, the end surface 14 aof the valve element 14 is an end surface of a disc-like part of the valve element 14 facing the pin 15 aof the rotation shaft 15.When the rotating shaft 15 rotates about the shaft axis Ls by a driving force Fm of the motor 32, the valve element 14 rotates integrally with the rotating shaft 15 about the shaft axis Ls. Thereafter, the valve element 14 is brought into contact with the lip portion 52 of the lip seal 51 as shown in FIG. 11. The valve element 14 is accordingly restricted in its integral rotation with the rotatable shaft 15 about the shaft axis Ls. The lip seal 51 thus stops the rotation of the valve element 14 that has rotated about the shaft axis Ls together with the rotation axis 15 when the valve element 14 comes into contact with the lip portion 52. The flow control valve 1 is in the set state at this time, and this state corresponds to a "rotation stop time" of the present invention.At this rotation stop time, the valve element end surface 14 ais in contact with the first side 61 of the stopper 53 of the rotatable shaft 15, and the eccentric axis Le is at a first position P 1 on a side opposite to the valve seat 13 (a side opposite to the valve seat 13) with respect to a horizontal straight line Lx extending through the shaft axis Ls and parallel to a radial direction of the valve element 14. Further, a straight line L 1 connecting the shaft axis Ls and the eccentric axis Le is inclined at an angle θ 1 to the horizontal straight line Lx.When the rotatable shaft 15 further rotates about the shaft axis Ls by the driving force Fm of the motor 32, the valve element 14 does not integrally rotate with the rotatable shaft 15 about the shaft axis Ls but moves toward the valve seat 13 as shown in FIG. 12. By this movement, the end face 14a of the valve element 14 comes into contact with the second side 62 of the stopper 53 of the rotatable shaft 15. More specifically, the lip seal 51 prevents the valve element 14 from integrally rotating with the rotatable shaft 15 about the shaft axis Ls, so that the valve element 14 instead relatively rotates about the eccentric axis Le with respect to the shaft 15 rotating about the shaft axis Ls. The rotation of the rotatable shaft 15 about the shaft axis Ls results in a movement of the eccentric axis Le towards the valve seat 13, which movement results in the valve element 14 moving towards the valve seat 13 and thus the end face 14 aof the valve element 14 comes into contact with the second side 62 of the stop 53. The flow control valve 1 is in the fully closed state at this time, and this state corresponds to a "abutting contact time" of the present invention.The lip seal 51 thus stops the rotation of the valve element 14 that has rotated about the shaft axis Ls together with the rotation shaft 15. Subsequently, the valve element 14 relatively rotates about the eccentric axis Le with respect to the rotatable shaft 15 rotating about the shaft axis Ls, so that the valve element 14 moves toward the valve seat 13.During the above operation, a spring force of the lip portion 52 generated when the lip portion 52 is pressed and bent by the valve element 14 is larger than the pressing force Fs of the spring 54 that presses the valve element 14 toward the stopper 53. Accordingly, the valve element 14 moves toward the valve seat 13 while maintaining its position when the valve element 14 comes into contact with the lip seal 51. The pressing force Fs is applied at this time in a direction opposite to a direction shown in FIGS. 10 and 11.Further, the eccentric axis Le is at a second position P 2 on a side facing the valve seat 13 with respect to the horizontal straight line Lx as shown in FIG. 12. The straight line L 1 connecting the shaft axis Ls and the eccentric axis Le is inclined at an angle θ 2 to the horizontal straight line Lx. The angle θ 1 is preferably equal to the angle θ 2.As shown in FIG. 13, a theoretical path TRo of the eccentric axis Le is considered to be a circular arc shape during a period from the set state (a state shown in FIG. 11 ) in which the valve element 14 is in contact with the lip portion 52 of the lip seal 51 to the fully closed state (a state shown in FIG. 12 ) of the flow control valve 1. More specifically, the valve element 14 theoretically moves relative to the lip seal 51 and slides with the lip seal 51 by a moving amount X in the direction of the horizontal straight line Lx in FIG. 13. However, actually, the occurrence of a frictional force between the valve element 14 and the rotatable shaft 15 prevents the valve element 14 from slipping with the rotatable shaft 15.In the present embodiment, a clearance amount δ (see FIG. 13 ) of the first bearing 37 and the second bearing 38 defined as a relative movement amount of the rotatable shaft 15 moving in the radial direction of the rotatable shaft 15 with respect to the first bearing 37 and the second bearing 38 is set to be larger than the movement amount X. This results in restraining the slippage of the valve element 14 and the lip seal 51 and also results in the counter movement of the rotatable shaft 15 in the radial direction by the amount of movement X in the present embodiment. Accordingly, an actual trajectory TR of the eccentric axis Le when the eccentric axis Le moves from the first position P 1 to the second position P 2 is not shown to be circular but linearly illustrated as shown in FIG. 13. The valve element 14 and the lip seal 51 are thus prevented from slipping. In FIG. 13, a distance between the first position P 1 and the second position P 2 corresponds to a pressing amount by which the valve element 14 presses the valve seat 13 (more specifically, the lip seal 51).The flow control valve 1 of the present embodiment includes two bearings, the first bearing 37 and the second bearing 38, but alternatively, one bearing may be provided instead of the first bearing 37 and the second bearing 38, or three or more bearings may be provided.The flow control valve 1 of the present embodiment includes the lip seal 51 as described above. this lip seal 51 is configured to stop the rotation of the valve element 14 rotating about the shaft axis Ls together with the rotatable shaft 15 and to cause the valve element 14 to rotate about the eccentric axis Le relative to the rotatable shaft 15 which has rotated about the shaft axis Ls. Accordingly, the valve element 14 moves toward the valve seat 13.As mentioned above, the valve element 14 stops rotating at the transition from the open to the fully closed state and then moves toward the valve seat 13. This achieves a limitation on the abrasion between the valve seat 13 (particularly, the lip seal 51) and the valve element 14 caused by the rotational movement of the valve element 14 on the valve seat 13 and the vicinity thereof. Further, the valve element 14 can be firmly pressed against the valve seat 13, thereby improving the sealing effect between the valve seat 13 and the valve element 14. Therefore, the flow passage 11 is securely sealed in the fully closed state.In the present embodiment, the flow control valve 1 includes the stopper 53 to define an allowable range in which the valve element 14 can relatively rotate about the eccentric axis Le with respect to the rotatable shaft 15, and the spring 54 provided between the valve element 14 and the rotatable shaft 15 to urge the valve element 14 toward the stopper 53. The lip seal 51 is formed with the lip portion 52 that is pressed and bent by the valve element 14 as the valve element 14 moves toward the valve seat 13. The spring force of the lip portion 52 generated when the lip portion 52 is bent is larger than the pressing force Fs of the spring 54 that presses the valve element 14 toward the stopper 53. Thus, the valve element 14 moves toward the valve seat 13 while maintaining its position when the valve element 14 comes into contact with the lip seal 51. As a result, the sealing effect between the valve seat 13 and the valve element 14 is increased.In the present embodiment, at the rotation stop timing when the lip seal 51 stops the rotation of the valve element 14, i.e., in the set state, the eccentric axis Le is at the first position P 1 on a side opposite to the valve seat 13 with respect to the horizontal straight line Lx. At the stopper contact timing after the rotation stop timing, when the lip seal 51 brings the valve element 14 toward the valve seat 13 and the valve element 14 comes into contact with the second side 62 of the stopper 53, i.e., in the fully closed state, the eccentric axis Le is at the second position P 2 on a side close to the valve seat 13 with respect to the horizontal straight line Lx. The valve element 14 thus moves further toward the valve seat 13 after coming into contact with the lip seal 51. This achieves an improvement in the sealing effect between the valve seat 13 and the valve element 14.In the present embodiment, the play amount δ of the first bearing 37 and the second bearing 38 is larger than the movement amount of the rotatable shaft 15 that moves in the radial direction while the eccentric axis moves from the first position P 1 to the second position P 2. Thereby, movement of the rotatable shaft 15 in the radial direction is achieved without being restricted by the first bearing 37 and the second bearing 38 when the flow control valve 1 is brought from the set state to the fully closed state. Consequently, movement of the valve element 14 caused by the movement of the rotatable shaft 15 is prevented, and thus the slipping of the valve element 14 with the lip seal 51 is prevented.Further, in the present embodiment, the stopper 53 is a protrusion formed integrally with the rotatable shaft 15. This integral structure reduces the number of components, thereby achieving cost reduction.An application example of the flow control valve 1 of the present embodiment will be described below. The flow control valve 1 of the present embodiment is configured as, for example, an air system 113 built-in valve 181 in a fuel cell system 101 which will be explained later. The fuel cell system 101 will be described below.The fuel cell system 101 is installed in an electric car and is for supplying power to a driving motor (not shown) for the electric car. The fuel cell system 101 includes a fuel cell (a fuel cell stack, FC stack) 11, a hydrogen system 112, and the air system 113 as shown in FIG. 14.The fuel cell 111 generates power upon receiving the supplied fuel gas and the supplied oxidizing gas. In the present embodiment, the fuel gas is hydrogen gas and the oxidizing gas is air. More specifically, the fuel cell 111 is configured to generate electric power upon receiving hydrogen gas supplied from the hydrogen system 112 and air supplied from the air system 113. The electric power generated in the fuel cell 111 is supplied to a drive motor (not shown) via an inverter (not shown).The hydrogen system 112 is provided on an anode side of the fuel cell 111. This hydrogen system 112 includes a hydrogen supply channel 121, a hydrogen discharge channel 122, and a filling channel 123. The hydrogen supply channel 121 is a flow channel for supplying hydrogen gas from a hydrogen tank 131 into the fuel cell 111. The hydrogen discharge channel 122 is a flow channel for discharging hydrogen gas to be discharged from the fuel cell 111 (hereinafter, appropriately referred to as "hydrogen off-gas"). The filling channel 123 is a flow channel for filling hydrogen gas into the hydrogen tank 131 through a filling opening 151.The hydrogen system 112 includes, at the hydrogen supply passage 121, a main cut valve 132, a high-pressure regulator 133, an intermediate-pressure relief valve 134, a pressure sensor 135, an injector portion 136, a low-pressure relief valve 137, and a pressure sensor 138, which are arranged in this order from the hydrogen tank 131. The main stop valve 132 is a valve for switching on and off supply of hydrogen gas from the hydrogen tank 131 to the hydrogen supply channel 121. The high pressure regulator 133 is a pressure regulating valve for reducing the pressure of the hydrogen gas. The medium-pressure relief valve 134 is a valve configured to open when the pressure in the hydrogen supply passage 121 between the high-pressure regulator 133 and the injector portion 136 reaches or exceeds a predetermined pressure to adjust the pressure to be below the predetermined pressure. The pressure sensor 135 is a sensor for detecting the pressure in the hydrogen supply passage 121 between the high-pressure regulator 133 and the injector portion 136. The injector portion 136 is a mechanism for regulating the flow rate of hydrogen gas. The low-pressure spill valve 137 is a valve configured to open when the pressure in the hydrogen supply passage 121 between the injector portion 136 and the fuel cell 111 reaches or exceeds a predetermined pressure to set the pressure below the predetermined pressure. The pressure sensor 138 is a sensor for detecting the pressure in the hydrogen supply passage 121 between the injector portion 136 and the fuel cell 111.The hydrogen system 112 further includes, at the hydrogen discharge passage 122, a gas-liquid separator 141 and an exhaust discharge valve 142 arranged in this order from the fuel cell 111 side. The gas-liquid separator 141 is a device for separating moisture from the hydrogen off-gas. The exhaust discharge valve 142 is a valve for turning on and off the discharge of hydrogen gas and moisture from the gas-liquid separator 141 to a diluter 182 of the air system 113.The air system 113 is provided at a cathode side of the fuel cell 111. This air system 113 includes an air supply passage 161, an air discharge passage 162, and a bypass passage 163. The air supply passage 161 is a flow passage for supplying air from the outside of the fuel cell system 101 into the fuel cell 111. The air discharge passage 162 is a flow passage for discharging air to be discharged from the fuel cell 111 (hereinafter, appropriately referred to as "air exhaust gas"). The bypass passage 163 is a flow passage that allows air to flow from the air supply passage 161 to the air discharge passage 162 without passing through the fuel cell 111.The air system 113 further includes, at the air supply passage 161, an air pump 172, an intercooler 173, and a sealing valve 174 arranged in this order from one side of an air cleaner 171. The air cleaner 171 is a device for purifying air externally taken in the fuel cell system 101. The air pump 172 is a device for adjusting a flow rate of the air. The intercooler 173 is a device for cooling air. The seal valve 174 is a valve for turning on and off supply of air flowing to the fuel cell 111.The air system 113 further includes, at the air discharge passage 162, an installation valve 181 and a diluter 182 disposed in this order from the fuel cell 111 side.The built-in valve 181 is a valve for turning on and off the discharge of air off gas from the fuel cell 111 (a valve having an air-tight function), and a valve for controlling the amount of air off gas discharged from the fuel cell 111 (a valve having a current-regulating function). In the present embodiment, the above-described flow control valve 1 is used as the built-in valve 181. In FIGS. 3 and 4, the flow passage 11 is provided on a side opposite to the valve element 14 and the rotatable shaft 15 with respect to the valve seat 13 near the fuel cell 111, and the flow passage 11 is disposed on a side of the valve element 14 and the rotatable shaft 15 near the diluter 182 with respect to the valve seat 13. More specifically, air in the flow passage 11 flows through the built-in valve 181 from a side of the valve seat 13 toward the valve element 14 (the rotatable shaft 15).The diluter 182 is a device for diluting hydrogen off-gas discharged from the hydrogen discharge passage 122 by the air off-gas and the air flowing through the bypass passage 163.The air system 113 further includes a bypass valve 191 at the bypass passage 163. The bypass valve 191 is a valve for regulating an air flow rate in the bypass passage 163.The fuel cell system 101 is further provided with a controller 201 for controlling the system. More specifically, the controller 201 is configured to control each component or device of the fuel cell system 101. In addition, the fuel cell system 101 includes a cooling system (not shown) for cooling the fuel cell 111.In the fuel cell system 101 configured as described above, the hydrogen gas supplied to the fuel cell 111 through the hydrogen supply passage 121 is consumed in the fuel cell 111 for power generation, and then discharged to the outside of the fuel cell system 101 as hydrogen off-gas from the fuel cell 111 via the hydrogen discharge passage 122 and the diluter 182. The air supplied to the fuel cell 111 through the air supply passage 161 is consumed in the fuel cell 111 for power generation, and then discharged as an air off-gas from the fuel cell 111 to the outside of the fuel cell system 101 via the air discharge passage 162 and the diluter 182.In the fuel cell system 101 described above, by using the flow control valve 1 of the present embodiment as the built-in valve 181 in the air system 113, it is possible to achieve a restriction on abrasion between the valve seat 13 and the valve element 14 caused by a rotational movement of the valve element 14 on the valve seat 13 and the vicinity thereof. The built-in valve 181 can thus have a reliable sealing effect in the completely closed state. This results in improved airtight sealing of the fuel cell 111 in the fully closed state of the built-in valve 181 when power generation in the fuel cell 111 is interrupted. Accordingly, fewer reactions take place in the fuel cell 111, and thus the oxidation-related deterioration of the fuel cell 111 is prevented.The flow control valve 1 of the present embodiment can be used as the sealing valve 174 and the bypass valve 191 of the air system 113 in the fuel cell system 101.According to an exemplary embodiment, the flow control valve 1 may be provided with a protruding part 71 protruding from the valve seat 13 toward the valve element 14, as shown in FIG. 15. The protruding part 71 has a side surface 72 (a guide portion). The side surface 72 comes into contact with a distal end 14 bextending in the rotational direction of the valve element 14 when the valve element 14 has rotated about the shaft axis Ls together with the rotatable shaft 15 and stops rotating. The side surface 72 then guides the valve element 14 in its movement toward the valve seat 13, while the valve element 14 rotates about the eccentric axis Le relative to the rotatable shaft 15 and moves toward the valve seat 13. The protruding part 71 corresponds to an example of the "valve element moving direction restricting part" of the present invention. The valve seat 13 is provided with a sealing member 81 for securing the sealing action of the valve element 14 in the fully closed state. The flow control valve 1 of the exemplary embodiment is thus configured such that the side surface 72 of the protruding part 71 guides the movement of the valve element 14 and thus limits the abrasion between the valve seat 13 (sealing member 81) and the valve element 14 caused by the rotational movement of the valve element 14 on the valve seat 13 and the vicinity thereof.The above-described embodiment is merely exemplary, and the present invention is not limited to the above-described embodiment. The present invention can be applied with various modifications and improvements without departing from the subject matter thereof.List of Reference Numerals1 Flow control valve 13 Valve seat 14 Valve element 15 Rotatable shaft 15 aPin 16 Valve hole 17 Seat surface 18 Sealing surface 32 Motor 37 First bearing 38 Second bearing 51 Lip seal 52 Lip portion 53 Stopper 54 Spring 61 First side 62 Second side 71 Protruding part 72 Side surface 101 Fuel cell system 111 Fuel cell 112 Hydrogen system 113 Air system 162 Air discharge passage 174 Sealing valve 181 Built-in valve 191 Bypass valve Ls Shaft axis Lh Center axis (of the valve hole) Lv Center axis (of the valve element) Le Eccentric axis L 1 Straight line (connecting the shaft axis and the eccentric axis) Lx Horizontal straight line Fs Pressing force Fm Driving force of the motor P 1 First position P 2 Second position θ 1 Angle θ 2 Angle X Movement amount δ Clearance

Claims

A flow control valve (1) comprising: a valve seat (13) having a valve hole (16) and a seat surface (17) formed on an edge of the valve hole; a valve element (14) formed on an outer periphery with a sealing surface (18) corresponding to the seat surface (17); and a rotatable shaft (15) integrally provided with the valve element (14), wherein the rotatable shaft (15) has a central axis (Ls) arranged eccentrically from a central axis (Lh) of the valve hole (16) in a radial direction of the valve hole, and wherein the sealing surface (18) is arranged eccentrically from the central axis (Ls) of the rotatable shaft (15) toward an extending direction of a central axis (Lv) of the valve element (14), wherein the flow control valve (1) further has a valve element moving direction restricting part (51) configured to:, stopping the rotation of the valve element (14) rotatable together with the rotatable shaft (15) about the rotatable shaft central axis (Ls), and thereafter rotating the valve element (14) about an eccentric axis -(Le) disposed eccentrically from the rotatable shaft central axis (Ls) (15) relative to the rotatable shaft (15) rotatable about the rotatable shaft central axis (Ls) (15) such that the valve element (14) moves toward the valve seat (13), characterized in that the flow control valve (1) comprises: a stopper (53) for defining a range of relative rotation of the valve element (14) configured to rotate about the eccentric axis (Le) relative to the rotatable shaft (15); and a spring (54) provided between the rotatable shaft (15) and the valve element (14) for urging the valve element (14) toward the stopper (53), wherein the valve element moving direction restricting part (51) constitutes a part of the valve seat (13) and has a lip portion (52) configured to be pressed and bent by the valve element (14) when the valve element (14) moves toward the valve seat (13), and wherein a spring force generated in the lip portion (52) when the lip portion (52) is bent is larger than a pressing force of the spring (54) urging the valve element (14) toward the stopper (53).The flow control valve (1) according to claim 1, wherein at a rotation stop timing when the valve element moving direction restricting part (51) stops the rotation of the valve element (14), the eccentric axis (Le) is disposed in a first position (P1) that is an opposite side to the valve seat (13) with respect to a horizontal straight line (Lx) extending through the central axis (Ls) of the rotatable shaft (15) and parallel to a radial direction of the valve element (14), and at a stopper contact timing after the rotation stop timing when the valve element moving direction restricting part (51) brings the valve element (14) toward the valve seat (13) to bring the valve element into contact with the stopper (53), The eccentric axis (Le) is disposed at a second position (P 2) on a side close to the valve seat ( 13) with respect to the horizontal straight line (Lx).The flow control valve (1) according to claim 2, wherein the flow control valve comprises a bearing (37, 38) for supporting the rotatable shaft (15), and the rotatable shaft (15) has an allowable amount of movement of relative movement in the radial direction of the rotatable shaft (15) with respect to the bearing (37, 38), the allowable amount of movement being larger than an amount of movement of the rotatable shaft (15) when moving in the radial direction of the rotatable shaft (15) when the eccentric axis (Le) moves between the first position (P1) and the second position (P2).The flow control valve (1) according to any one of claims 1 to 3, wherein the stopper (53) is a protrusion formed integrally with the rotatable shaft (15).

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