Flow rate control valve

Abstract

When a piston member 80 is moved to the other axial-direction side of a shaft member 70 by the air pressure in an air chamber 33, respective spherical bodies 41 are moved to the other axial-direction side of the shaft member 70 and are moved to the radial-direction outer side of the shaft member 70. As a result, the amount of movement of the spherical bodies 41 to the other axial-direction side is reduced in relation to the amount of movement of the piston member 80 to the other axial-direction side, and thus the amount of movement of the shaft member 70 (valve body) to the other axial-direction side can be reduced. Accordingly, gradually increasing the air pressure inside the air chamber 33 makes it possible to gradually increase the flow rate of a fluid and thus accurately control a valve body for opening and closing a flow passage.

Description

Flow Control Valve

[0001] The present disclosure relates to a flow control valve having a valve body that is actuated by air pressure to open and close a flow path.

[0002] For example, Patent Document 1 describes a diaphragm-type flow control valve having a valve body with a fluid passage, a valve seat disposed in the fluid passage, and a diaphragm with a valve element pressed against the valve seat. The diaphragm is attached to a lower rod of a piston, and the valve element of the diaphragm is biased toward the valve seat by a spring. When air is supplied to the lower chamber of the cylinder, the piston rises against the biasing force of the spring, and the valve element moves away from the valve seat (opening the valve).

[0003] Japanese Patent Application Publication No. 10-153268

[0004] However, with the technology described in Patent Document 1, it is difficult to precisely adjust the air pressure and control the opening of the valve element with high precision.

[0005] An object of the present disclosure is to provide a flow control valve that is capable of more accurately controlling a valve element that opens and closes a flow path by air pressure.

[0006] The present disclosure provides a flow control valve having a valve element that is actuated by air pressure to open and close a flow path, the valve element being provided inside the housing, an axial member that is movably accommodated inside the housing, the valve element being provided on one axial side, and a protrusion that protrudes radially outward on the other axial side, a piston member that is provided radially outward of the axial member and moved by the air pressure to the other axial side of the axial member relative to the axial member, a sphere that is provided between the protrusion along the axial direction of the axial member and the piston member and that comes into contact with each of the protrusion and the piston member, and a sphere support member that is provided radially outward of the piston member and supports the sphere, and when the piston member is moved by the air pressure to the other axial side of the axial member, the sphere moves to the other axial side of the axial member and radially outward of the axial member.

[0007] According to the present disclosure, the amount of axial movement of the shaft member toward the other side can be made smaller than the amount of axial movement of the piston member toward the other side, thereby making it possible to more precisely control the valve body that opens and closes the flow path.

[0008] 5 is a cross-sectional view of the flow control valve of embodiment 1 when the valve is closed. FIG. 5 is an enlarged view of the periphery of the sphere of FIG. 1. FIG. 5 is a cross-sectional view taken along line A-A of FIG. 1. FIG. 5 is an enlarged view of part B of the dashed circle of FIG. 1. FIG. 5 is a cross-sectional view of the flow control valve of FIG. 1 when the valve is open. FIG. 5 is a cross-sectional view taken along line C-C of FIG. 5. FIG. 5 is an enlarged view of part D of the dashed circle of FIG. 5. FIG. 5 is an explanatory diagram illustrating the operation of the flow control valve of embodiment 1. FIG. 5 is a graph comparing changes in flow rate relative to air pressure between embodiment 1 and a comparative example. FIG. 5 is a cross-sectional view of the flow control valve of embodiment 2 when the valve is closed. FIG. 5 is a cross-sectional view of the flow control valve of FIG. 10 when the valve is open.

[0009] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0010] <Embodiment 1> Fig. 1 is a cross-sectional view of a flow control valve of embodiment 1 when the valve is closed. Fig. 2 is an enlarged view of the periphery of a sphere in Fig. 1. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 1. Fig. 4 is an enlarged view of part B circled by a dashed line in Fig. 1. Fig. 5 is a cross-sectional view of the flow control valve of Fig. 1 when the valve is open. Fig. 6 is a cross-sectional view taken along line C-C in Fig. 5. Fig. 7 is an enlarged view of part D circled by a dashed line in Fig. 5.

[0011] <Overview of Flow Control Valve> The flow control valve 10 shown in Figures 1 to 7 is applied to, for example, a semiconductor manufacturing line. Specifically, the flow control valve 10 is used to drip a specified amount of resist solution onto a rotating wafer. Because the resist solution used in semiconductor manufacturing lines is relatively expensive, it is desirable to eliminate waste as much as possible. To this end, the flow control valve 10 according to this embodiment is capable of controlling the flow rate with greater precision, that is, capable of adjusting the flow rate more finely.

[0012] <Housing> The flow control valve 10 has a housing 11 that forms the outer shell of the flow control valve 10. The housing 11 is made up of a flow path forming block 20, an air chamber forming block 30, a sphere accommodating block 40, and a cover member 50. The flow path forming block 20, the air chamber forming block 30, the sphere accommodating block 40, and the cover member 50 are stacked together in this order from bottom to top as shown in Figures 1 and 5 to form an integrated unit.

[0013] 1 and 5, an upstream flow path (flow path) 21 disposed upstream in the direction of fluid (not shown) flow (see reference symbol IN in the drawings) and a downstream flow path (flow path) 22 disposed downstream in the direction of fluid flow (see reference symbol OUT in the drawings) are provided inside the flow path forming block 20. An upstream pipe connection 21a, to which an upstream pipe (not shown) is connected, is provided further upstream (to the right in the drawings) of the upstream flow path 21. Furthermore, a downstream pipe connection 22a, to which a downstream pipe (not shown) is connected, is provided further downstream (to the left in the drawings) of the downstream flow path 22.

[0014] An annular valve seat 23 is provided at the connection between the downstream side of the upstream flow path 21 and the upstream side of the downstream flow path 22. A valve portion 61 of a valve element 60 is removably seated on the valve seat 23. When the valve portion 61 is seated on the valve seat 23 and the valve is closed, the flow of fluid from the upstream flow path 21 to the downstream flow path 22 is blocked, as indicated by the dashed arrow in Fig. 4. In contrast, when the valve portion 61 is separated from the valve seat 23 and the valve is opened, the flow of fluid from the upstream flow path 21 to the downstream flow path 22 is permitted, as indicated by the solid arrow in Fig. 7.

[0015] A valve chamber 24 is provided inside the flow path forming block 20 and above the valve seat 23, i.e., on the side where the air chamber forming block 30 is provided. Inside the valve chamber 24, a valve portion 61 of a valve element 60 is arranged so as to be movable up and down (liftable).

[0016] Here, the valve element 60 includes a valve portion 61, an elastic membrane portion 62 integrally provided on the outer periphery of the valve portion 61, and an annular clamping portion 63 integrally provided on the outer periphery of the elastic membrane portion 62. A cylindrical fixing portion 64 is integrally provided on the side of the valve portion 61 opposite to the side where the valve seat 23 is provided along the axial direction (upper side in the figure). In this way, the valve element 60 employs a diaphragm-type valve element.

[0017] The annular clamping portion 63 is sandwiched between the flow path forming block 20 and the air chamber forming block 30. This prevents fluid from leaking from inside the valve chamber 24 to outside the valve chamber 24. The cylindrical fixing portion 64 is fixed to a shaft member 70 that is movable up and down inside the housing 11. As a result, as the shaft member 70 moves up and down (up and down movement), the valve portion 61 moves with respect to and away from the valve seat 23, allowing or blocking the flow of fluid.

[0018] 1 and 5, the air chamber forming block 30 includes a first sliding cylindrical portion 31 and a second sliding cylindrical portion 32 having a larger diameter than the first sliding cylindrical portion 31. Specifically, one axial side (lower in the figure) of the shaft member 70 is slidably housed radially inside the first sliding cylindrical portion 31. On the other hand, one axial side (lower in the figure) of the piston member 80 is slidably housed radially inside the second sliding cylindrical portion 32.

[0019] The first sliding cylindrical portion 31 is disposed on one axial side (lower in the figure) of the air chamber forming block 30, and the second sliding cylindrical portion 32 is disposed on the other axial side (upper in the figure) of the air chamber forming block 30. Furthermore, an air chamber 33 formed in a substantially cylindrical shape is provided on one axial side of the air chamber forming block 30 and radially outward of the first sliding cylindrical portion 31. That is, the air chamber 33 is aligned with the first sliding cylindrical portion 31 in the radial direction of the air chamber forming block 30, and faces one axial side of the piston member 80 in the axial direction of the air chamber forming block 30.

[0020] An air pressure supply port 35 is connected to the air chamber 33 via an air passage 34. An air pressure adjusting device (not shown) that can accurately adjust the pressure (air pressure) inside the air chamber 33 is connected to the air pressure supply port 35. As a result, by increasing the air pressure in the air chamber 33, the piston member 80 is moved upward (driven upward), and by decreasing the air pressure in the air chamber 33, the piston member 80 is moved downward (driven downward).

[0021] In this way, the air chamber 33 is arranged on one axial side of the shaft member 70, and air pressure is introduced into the air chamber 33 to urge the piston member 80 toward the other axial side of the shaft member 70.

[0022] An annular piston abutment surface 31a is provided on the other axial side (upper side in the figure) of the first sliding cylindrical portion 31. Specifically, when the air pressure in the air chamber 33 is low, one axial side (lower side in the figure) of the piston member 80 abuts against the piston abutment surface 31a. In this way, the piston abutment surface 31a of the first sliding cylindrical portion 31 has the function of determining the reference position of the piston member 80 (the valve-closed position of the valve body 60) when the air pressure in the air chamber 33 is low.

[0023] Furthermore, a first breathing hole HL1 that communicates between the inside and outside of the air chamber forming block 30 is provided on one axial side of the air chamber forming block 30. Air flows through the first breathing hole HL1 as the valve body 60 opens and closes. In other words, the first breathing hole HL1 allows the volume inside the air chamber forming block 30 to change as the valve body 60 opens and closes. This allows the elastic membrane portion 62 of the valve body 60 to bend easily.

[0024] 1 to 3, 5, and 6, the sphere containing block 40 is provided with a sphere containing chamber 42 that contains a total of six spheres 41. The sphere containing chamber 42 includes a large-diameter chamber 42a located on one axial side of the sphere containing block 40 (lower side in FIG. 2), and a small-diameter chamber 42b located on the other axial side of the sphere containing block 40 (upper side in FIG. 2) and having a diameter slightly smaller than that of the large-diameter chamber 42a.

[0025] Additionally, an annular step portion 42c is provided between the large diameter chamber 42a and the small diameter chamber 42b along the axial direction of the sphere accommodating block 40. The sphere support member 90 abuts against the annular step portion 42c from the other axial side of the sphere accommodating block 40, thereby restricting movement of the sphere support member 90 to the other axial side. Note that the sphere support member 90 is movable in the axial direction of the shaft member 70, radially inside the large diameter chamber 42a.

[0026] Furthermore, the other axial side of the piston member 80 is disposed radially inside the large diameter chamber 42a that forms the sphere accommodating block 40. That is, the other axial side of the piston member 80 and the sphere support member 90 overlap each other in the radial direction of the large diameter chamber 42a. Furthermore, the protruding portion 73b of the flange member 73 fixed to the other axial side of the shaft member 70 is disposed radially inside the small diameter chamber 42b that forms the sphere accommodating block 40.

[0027] 1, 2, and 5, a total of six spheres 41 are disposed between the piston member 80, the sphere support member 90, and the flange member 73. Here, when the valve element 60 is closed in the usage position of the flow control valve 10 shown in FIGS. 1, 2, and 5, that is, in the usage position with one axial side facing downward and the other axial side facing upward, as shown in FIGS. 1 and 2, each sphere 41 comes into point contact with the piston member 80 and the sphere support member 90, and a gap MG is formed between each sphere 41 and the flange member 73.

[0028] In contrast, when the valve element 60 is open, as shown in Fig. 5, each of the spheres 41 comes into point contact with the piston member 80, the sphere support member 90, and the flange member 73, respectively. In this embodiment, steel spheres are used as the spheres 41. Therefore, the spheres 41 have high rigidity.

[0029] Furthermore, a first coil spring (spring member) SP1 is housed inside the sphere containing block 40. Specifically, the first coil spring SP1 is disposed between the piston member 80 and the sphere support member 90 along the axial direction of the shaft member 70. In other words, the spring force of the first coil spring SP1 acts in a direction that moves the sphere support member 90 and the piston member 80 away from each other.

[0030] Specifically, the first coil spring SP1 disposed between the piston member 80 and the sphere support member 90 has the function of abutting the piston member 80 against the piston abutment surface 31 a and abutting the sphere support member 90 against the annular step portion 42 c when the valve body 60 is closed. When the valve body 60 is closed, a gap MG is formed between each sphere 41 and the flange member 73, so the spring force of the first coil spring SP1 does not affect the pressing force of the valve body 60 against the valve seat 23 (the spring force of the second coil spring SP2).

[0031] That is, by adjusting only the spring force of the first coil spring SP1, the timing at which the air pressure in the air chamber 33 causes the piston member 80 to separate from the piston abutment surface 31a and begin to rise can be easily set.

[0032] 3 and 6, the sphere containing block 40 is formed in a substantially square shape when viewed from the axial direction of the shaft member 70. A total of four holes 43 are provided surrounding the large-diameter chamber 42a and the small-diameter chamber 42b. These holes 43 are arranged at equal intervals (90-degree intervals) around the large-diameter chamber 42a and the small-diameter chamber 42b. A fixing screw SC for fixing the cover member 50 to the sphere containing block 40 is screwed into the other axial side of each hole 43 (upper side in FIG. 2).

[0033] 1, 2, and 5, the cover member 50 is formed in a generally hat shape and includes a cylindrical wall portion 51. An opening 51a is provided on one axial side (the lower side in FIG. 2) of the cylindrical wall portion 51, and an annular flange 51b is integrally provided on the radially outer side of the opening 51a. The annular flange 51b is the portion against which the sphere containing block 40 abuts from one axial side of the shaft member 70, and includes an insertion hole 51c through which the fixing screw SC is inserted.

[0034] One axial end of the cylindrical wall portion 51 is inserted into the small diameter chamber 42b of the sphere accommodating block 40. One axial end of the cylindrical wall portion 51 is provided with an annular protrusion abutment surface 51d against which the protrusion 73b of the flange member 73 abuts when the valve element 60 is fully open. This determines the maximum flow rate of the fluid flowing through the upstream flow path 21 and the downstream flow path 22 (see FIGS. 1 and 5) when the valve element 60 is fully open. The protrusion 73b of the flange member 73 abuts against the protrusion abutment surface 51d, which also prevents the valve element 60 from opening too far and damaging the elastic membrane portion 62.

[0035] Furthermore, a bottom wall portion 52 that closes the other axial side of the cylindrical wall portion 51 (upper side in FIG. 2 ) is integrally provided. The cylindrical wall portion 51 is also provided with a second breather hole HL2 that allows for changes in the volume inside the cover member 50. Specifically, the second breather hole HL2 communicates between the inside and outside of the cover member 50, allowing air to circulate as the shaft member 70 and the piston member 80 move inside the housing 11. Therefore, both the shaft member 70 and the piston member 80 can move smoothly inside the housing 11.

[0036] 1 to 7, the shaft member 70 is movably accommodated inside the housing 11. The shaft member 70 includes a large-diameter shaft portion 71 disposed on one axial side (lower in FIG. 1) and a small-diameter shaft portion 72 disposed on the other axial side (upper in FIG. 1) and having a smaller diameter than the large-diameter shaft portion 71.

[0037] One axial side of the large diameter shaft portion 71 slidably fits into the radially inner side of the first sliding cylindrical portion 31, and the other axial side of the large diameter shaft portion 71 slidably supports the large diameter base end portion 81 of the piston member 80. A first seal member SL1 that seals between the large diameter shaft portion 71 and the first sliding cylindrical portion 31 is provided on one axial side of the large diameter shaft portion 71. A second seal member SL2 that seals between the large diameter shaft portion 71 and the large diameter base end portion 81 is provided on the other axial side of the large diameter shaft portion 71.

[0038] Furthermore, a valve element fixing hole 71a is provided on one axial side of the large diameter shaft portion 71. The valve element fixing hole 71a extends to the other axial side of the large diameter shaft portion 71, and the cylindrical fixing portion 64 of the valve element 60 is fixed to the valve element fixing hole 71a by screwing or the like. In this manner, the valve element 60 is integrally provided on one axial side of the shaft member 70, and the valve portion 61 of the valve element 60 is movable together with the shaft member 70. In other words, the valve element 60 integrated with the shaft member 70 is moved via the piston member 80 and the spherical body 41 as the air pressure in the air chamber 33 increases, thereby opening and closing the upstream flow path 21 and the downstream flow path 22 of the flow path forming block 20.

[0039] A small diameter tip portion 82 of a piston member 80 is disposed on one axial side (lower side in FIG. 2 ) of the small diameter shaft portion 72 and radially outward of the small diameter shaft portion 72 via a small gap, thereby allowing the piston member 80 to move smoothly relative to the shaft member 70. A male threaded portion 72a is provided on the other axial side (upper side in FIG. 2 ) of the small diameter shaft portion 72, and a flange member 73 and a fixing nut 74 are threadedly coupled to the male threaded portion 72a.

[0040] The flange member 73 includes a female threaded portion 73a that is threadedly coupled to the male threaded portion 72a, and a protruding portion 73b that protrudes radially outward from one axial side (the lower side in FIG. 2 ) of the female threaded portion 73a. Specifically, the protruding portion 73b is provided in a substantially circular plate shape around the entire circumference of the flange member 73, and the outer periphery of the protruding portion 73b is located near the small diameter chamber 42b of the sphere containing block 40. In other words, the protruding portion 73b that protrudes radially outward is integrally provided on the other axial side of the shaft member 70.

[0041] When viewed in the axial direction of the shaft member 70, the protruding portion 73b overlaps with a portion of the piston member 80 and the sphere support member 90. As a result, the sphere 41 disposed between the piston member 80, the sphere support member 90, and the flange member 73 is covered and hidden by the protruding portion 73b when viewed in the axial direction of the shaft member 70.

[0042] Furthermore, a second coil spring (return spring) SP2 is disposed on the opposite side of the protrusion 73b from the side on which the spherical body 41 is disposed (upper side in FIG. 2). The second coil spring SP2 is disposed between the bottom wall portion 52 of the cover member 50 and the protrusion 73b with a predetermined initial load applied, and the second coil spring SP2 urges the shaft member 70 downward via the flange member 73. In other words, the spring force of the second coil spring SP2 acts in a direction that presses the valve body 60 toward the valve seat 23 (to close the valve). In this way, the second coil spring SP2 that urges the valve body 60 in the valve closing direction is provided on the other axial side of the shaft member 70.

[0043] Here, when the valve element 60 is closed, a gap MG is formed between each of the spheres 41 and the protrusion 73b, so the spring force of the second coil spring SP2 does not affect the spring force of the first coil spring SP1. In other words, by adjusting the spring force of the second coil spring SP2, it is possible to easily set the timing at which the valve element 60 separates from the valve seat 23 and begins to rise (valve opening timing).

[0044] A first flat surface SF1 (see FIG. 2) is provided on the side of the protrusion 73b where the sphere 41 is disposed, with which the sphere 41 comes into contact at a point when the valve body 60 is open (OPEN), and which extends in a direction perpendicular to the axis of the shaft member 70. As a result, when the valve body 60 is open (see FIGS. 5 and 8), the sphere 41, which comes into contact at a point with the first flat surface SF1, is able to move in the radial direction of the shaft member 70 relative to the first flat surface SF1 while sliding against the first flat surface SF1.

[0045] Here, the flange member 73 is prevented from loosening by a fixing nut 74. That is, the fixing nut 74 functions as a so-called double nut.

[0046] 1, 2 and 5, the piston member 80 is accommodated movably inside the housing 11. The piston member 80 is provided radially outward of the shaft member 70 and is also movable relative to the shaft member 70 in the axial direction of the shaft member 70. Specifically, the piston member 80 is movable by air pressure in the air chamber 33 to the other axial side of the shaft member 70.

[0047] The piston member 80 has a cylindrical large-diameter base end portion 81 arranged on one axial side (lower in Figure 1) and a cylindrical small-diameter tip end portion 82 arranged on the other axial side (upper in Figure 1) and having a smaller diameter than the large-diameter base end portion 81.

[0048] The large diameter base end 81 has an inner peripheral portion that is slidable relative to the outer peripheral portion of the large diameter shaft portion 71, and an outer peripheral portion that is slidable relative to the inner peripheral portion of the second sliding cylindrical portion 32. The large diameter base end 81 is provided with a third seal member SL3 that seals the gap between the large diameter base end 81 and the second sliding cylindrical portion 32. The large diameter base end 81 is also provided with a stepped portion 81a (see FIG. 2), which supports one axial side (the lower side in FIG. 2) of the first coil spring SP1.

[0049] The small-diameter tip portion 82 is movably accommodated inside the sphere accommodation block 40. The other axial end side (upper side in FIG. 1 ) of the small-diameter tip portion 82 is tapered, and an annular second flat surface SF2 (see FIG. 2 ) is provided on the outer periphery of the other axial end side of the small-diameter tip portion 82. Specifically, the second flat surface SF2 is inclined downward from the radially inner side toward the radially outer side of the small-diameter tip portion 82. As shown in FIG. 8 , a perpendicular line PL2 (only one line is shown) of the second flat surface SF2 extends radially outward from the shaft member 70. More specifically, the perpendicular line PL2 extends between the protrusion 73 b and the sphere support member 90.

[0050] The sphere 41 is in point contact with the second plane SF2 when the valve body 60 is closed and when it is open, and the sphere 41 is in sliding contact with the second plane SF2 while being able to move in both the axial and radial directions of the shaft member 70 relative to the second plane SF2.

[0051] In this way, a total of six spheres 41 are arranged between the first plane SF1 of the protrusion 73b along the axial direction of the shaft member 70 and the second plane SF2 of the piston member 80, and when the valve body 60 is open, they are in point contact with each of the first plane SF1 and the second plane SF2.

[0052] 1, 2, and 5, the sphere support member 90 is movably accommodated within the housing 11. Specifically, the sphere support member 90 is provided radially outward of the piston member 80 and slidably disposed on the inner periphery of the large diameter chamber 42a in the sphere accommodation block 40. Thus, the sphere support member 90 is movable relative to both the protruding portion 73b of the shaft member 70 and the piston member 80. The sphere support member 90 includes a stepped portion 91 disposed on one axial side (lower in FIG. 2) and a support main body portion 92 disposed on the other axial side (upper in FIG. 2).

[0053] The stepped portion 91 faces the stepped portion 81 a of the piston member 80 in the axial direction of the shaft member 70. The stepped portion 91 supports the other axial side (upper side in FIG. 2 ) of the first coil spring SP1. The first coil spring SP1 is disposed between the stepped portion 81 a and the stepped portion 91 with a predetermined initial load applied. In other words, the first coil spring SP1 is disposed between the sphere support member 90 and the piston member 80 in the axial direction of the shaft member 70, and biases the sphere support member 90 and the piston member 80 in directions separating them from each other.

[0054] The support main body portion 92 is formed in a substantially cylindrical shape, and a curved surface CS (see FIG. 2) is provided on the other axial side (upper side in FIG. 2) of the support main body portion 92 so as to extend in the circumferential direction of the support main body portion 92. Specifically, the curved surface CS is disposed on the radially inner side of the support main body portion 92, and is formed in a convex shape facing between the protrusion 73b and the piston member 80, as shown in FIG.

[0055] The sphere 41 is in point contact with the curved surface CS when the valve element 60 is closed and when it is open, and the sphere 41 is capable of moving relative to the curved surface CS in both the axial direction and the radial direction of the shaft member 70 while rolling or sliding against the curved surface CS. In other words, the curved surface CS guides the movement of the sphere 41 radially outward from the shaft member 70.

[0056] In this way, the sphere support member 90 supports each of the spheres 41 when the valve body 60 is closed and when it is open.

[0057] <Explanation of Operation> Next, the operation of the flow control valve 10 configured as above will be described in detail with reference to the drawings.

[0058] Fig. 8 is an explanatory diagram illustrating the operation of the flow control valve of embodiment 1. Fig. 9 is a graph comparing the change in flow rate with respect to air pressure between embodiment 1 and a comparative example.

[0059] First, as shown in Figure 1, with the valve element 60 in a closed position, air at a predetermined pressure is supplied to the air pressure supply port 35. This causes air to be supplied to the air chamber 33 via the air passage 34, and the internal pressure of the air chamber 33 rises to the predetermined pressure. As a result, the piston member 80 is moved upward (upwardly driven) by the air pressure in the air chamber 33, and the sphere 41 is also pressed against the second flat surface SF2 (see Figure 8) and moved upward.

[0060] Thereafter, the spheres 41 pushed up by the piston member 80 move upward by the distance of the gap MG, and then come into point contact with the first flat surface SF1 of the protrusion 73b as shown in Fig. 8. As a result, each sphere 41 comes into point contact with each of the piston member 80, the sphere support member 90, and the flange member 73.

[0061] Next, as shown in Fig. 8, the sphere 41 moves along the path indicated by the dashed and dotted lines while rotating in the direction of arrow R around the point of contact (black dot) between the sphere 41 and the curved surface CS of the sphere support member 90. As a result, the first flat surface SF1 of the protrusion 73b is pushed up by the sphere 41, which moves the flange member 73 upward and also moves the shaft member 70 upward. Therefore, the valve element 60 attached to the shaft member 70 is opened as shown in Fig. 5.

[0062] Here, compared to when the piston member 80 directly pushes up the flange member 73, by using the sphere 41 supported at three points, the piston member 80, the sphere support member 90, and the flange member 73, it is possible to press the protrusion 73b with a relatively weak force, and the stroke of the piston member 80 at this time is long relative to the degree of opening of the valve body 60. This is because, as shown in Figure 8, as the sphere 41 rotates in the direction of arrow R around the contact point between the sphere 41 and the curved surface CS, the contact point between the sphere 41 and the curved surface CS functions as a "fulcrum," the contact point (black dot) between the sphere 41 and the second flat surface SF2 functions as a "point of force," and further the contact point (black dot) between the sphere 41 and the first flat surface SF1 functions as a "point of action," and these three points work according to the "lever principle."

[0063] As a result, protrusion 73b can be pressed with a relatively weak force, so that valve element 60 easily opens fully even when the air pressure in air chamber 33 is low, making it difficult to accurately control the opening of valve element 60. Therefore, as shown in Figure 2, a first coil spring SP1 is disposed between step portion 81a of piston member 80 and step-like portion 91 of sphere support member 90, and the spring force of this first coil spring SP1 acts to press piston member 80 downward.

[0064] Therefore, when the air pressure in the air chamber 33 is low, the piston member 80 can be moved slightly without moving significantly. Therefore, by controlling the air pressure in the air chamber 33 over a wide range from the low pressure side to the high pressure side, the opening degree of the valve body 60 can be controlled with high precision.

[0065] As the spheres 41 are pushed upward by the piston member 80, they gradually enter between the protrusion 73b and the support main body 92. As a result, the six spheres 41 change from a closed state (CLOSE) in which they are disposed radially inward as shown in Fig. 3 to an open state (OPEN) in which they are moved radially outward as shown in Fig. 6. In other words, when the piston member 80 is moved to the other axial side of the shaft member 70 by the air pressure in the air chamber 33, it moves the spheres 41 to the other axial side of the shaft member 70 and radially outward from the shaft member 70.

[0066] As a result, the amount of axial movement of the spherical body 41 toward the other side is reduced relative to the amount of axial movement of the piston member 80 toward the other side, and it is therefore possible to reduce the amount of axial movement of the shaft member 70 (valve body 60) toward the other side. Specifically, as shown in Figure 8, in the initial stage of the movement of the piston member 80 toward the other side in the axial direction, the amount of axial movement D2 of the spherical body 41 (shaft member 70) toward the other side is smaller than the amount of axial movement D1 of the piston member 80 toward the other side (D2<D1).

[0067] 8, when the sphere 41 enters further between the protrusion 73b and the support main body 92, the sphere 41 pushes the protrusion 73b further up toward the other axial side of the shaft member 70. Furthermore, the first coil spring SP1 is compressed, and the sphere support member 90 is pushed down toward one axial side of the shaft member 70. This further reduces the amount of movement of the sphere 41 (shaft member 70) toward the other axial side relative to the amount of movement of the piston member 80 toward the other axial side.

[0068] This can be represented graphically as shown in Figure 9. In the graph of Figure 9, the X axis represents the air pressure inside the air chamber 33, and the Y axis represents the flow rate of the fluid flowing inside the flow path forming block 20. The flow rate is proportional to the opening degree of the valve element 60.

[0069] In the first embodiment, as described above, the amount of axial movement of the shaft member 70 in the other direction can be made smaller than the amount of axial movement of the piston member 80 in the other direction (amount of piston member movement > amount of shaft member movement). Therefore, by gradually increasing the air pressure inside the air chamber 33, the flow rate of the fluid can be increased gradually.

[0070] Therefore, in the first embodiment, by controlling the air pressure in a relatively wide region AR1, the flow rate can be adjusted in a relatively narrow adjustment range FR on the low flow rate side, as shown by the solid line graph in Figure 9. This means that the valve element 60 that opens and closes the flow path can be controlled with high precision (fine adjustment).

[0071] On the other hand, in the comparative example (movement amount of the piston member = movement amount of the shaft member), as shown by the dashed line graph in Figure 9, when trying to adjust the flow rate with a relatively narrow adjustment range FR on the low flow rate side, it is necessary to control the air pressure inside the air chamber within a relatively narrow area AR2, which makes it difficult to control the air pressure.

[0072] The spring force of the first coil spring SP1 can be adjusted as desired according to the specifications of the flow control valve 10, and adjusting the spring force of the first coil spring SP1 makes it possible to adjust the operation (degree of opening) of the valve body 60. Specifically, if the spring force of the first coil spring SP1 is adjusted to be weaker, the rate of increase in the flow rate can be increased (the slope angle of the graph can be increased), and if the spring force of the first coil spring SP1 is adjusted to be stronger, the rate of increase in the flow rate can be decreased (the slope angle of the graph can be decreased).

[0073] To close the valve element 60, the air pressure in the air chamber 33 is reduced via the air passage 34 and the air pressure supply port 35. As a result, the spring force of the second coil spring SP2 presses down the sphere 41, which is in point contact with the first flat surface SF1 of the protruding portion 73b of the flange member 73.

[0074] At this time, the point of application of the sphere 41 shown in Figure 8 becomes the "point of force," while the point of force of the sphere 41 becomes the "point of action," and the sphere 41 rotates in the direction opposite to the direction of arrow R, pressing the piston member 80 downward. In this action of the sphere 41 to press down the piston member 80, the sphere 41 also acts like a "lever," so the sphere 41 presses down the piston member 80 with a relatively weak force. At this time, the spring force of the first coil spring SP1 acts to press down the piston member 80, so the downward movement speed of the piston member 80, i.e., the valve closing speed of the valve disc 60, does not change significantly with respect to the valve opening speed of the valve disc 60.

[0075] Here, as described above, the stroke of the piston member 80 is lengthened, so the time it takes for the valve element 60 to completely close is lengthened. As a result, the valve element 60 closes slowly, preventing the upstream flow path 21 and the downstream flow path 22 (see FIG. 5) from being suddenly closed. This makes it possible to mitigate the so-called "water hammer phenomenon" that occurs when the flow of fluid is suddenly blocked.

[0076] As described above in detail, according to embodiment 1, when the piston member 80 is moved to the other axial side of the shaft member 70 by the air pressure in the air chamber 33, it moves each of the spheres 41 to the other axial side of the shaft member 70 and radially outward from the shaft member 70.

[0077] As a result, the amount of axial movement of the spherical body 41 in the other axial direction is reduced relative to the amount of axial movement of the piston member 80 in the other axial direction, and thus the amount of axial movement of the shaft member 70 (valve body 60) in the other axial direction can be reduced. Therefore, by gradually increasing the air pressure inside the air chamber 33, the flow rate of the fluid can be gradually increased, and ultimately, the valve body 60, which opens and closes the flow path, can be controlled with high precision.

[0078] Furthermore, according to embodiment 1, the protrusion 73b has a first plane SF1 that extends in a direction perpendicular to the axis of the shaft member 70 and with which the sphere 41 comes into contact, and the piston member 80 has a second plane SF2 with which the perpendicular line PL2 extends between the protrusion 73b and the sphere support member 90 and with which the sphere 41 comes into contact.

[0079] This allows the sphere 41 to move radially outward, and guide the sphere 41 between the protrusion 73 b and the sphere support member 90 .

[0080] Furthermore, according to embodiment 1, the sphere support member 90 is formed convexly toward the area between the protrusion 73b and the piston member 80, and has a curved surface CS that contacts the sphere 41 and guides the movement of the sphere 41 radially outward.

[0081] This allows the sphere 41 to smoothly roll or slide against the curved surface CS and enter between the protrusion 73b and the sphere support member 90. This allows the valve element 60 to be opened and closed smoothly.

[0082] Furthermore, according to the first embodiment, the second coil spring SP2 is disposed on the other axial side of the shaft member 70 to bias the valve body 60 in the valve closing direction.

[0083] As a result, simply by lowering the air pressure inside the air chamber 33, the spring force of the second coil spring SP2 can return the valve body 60 to the closed state.

[0084] Furthermore, according to the first embodiment, the air chamber 33 into which air pressure is introduced to urge the piston member 80 in the other axial direction of the shaft member 70 is arranged on one axial side of the shaft member 70 .

[0085] This allows the flow control valve 10 to be used as a so-called air-operated valve in an environment such as a clean room where air cleanliness is maintained.

[0086] Furthermore, according to embodiment 1, the sphere support member 90 is movable relative to both the protrusion 73b and the piston member 80, and a first coil spring SP1 is provided between the sphere support member 90 and the piston member 80 in the axial direction of the shaft member 70, which urges the sphere support member 90 and the piston member 80 in a direction separating them from each other.

[0087] This makes it possible to further reduce the amount of axial movement of the spherical body 41 (shaft member 70) in the other axial direction relative to the amount of axial movement of the piston member 80 in the other axial direction, thereby enabling more precise control of the valve body 60 that opens and closes the flow path.

[0088] <Embodiment 2> Fig. 10 is a cross-sectional view of a flow control valve according to embodiment 2 when the valve is closed. Fig. 11 is a cross-sectional view of the flow control valve of Fig. 10 when the valve is open. Note that parts that are the same as those in embodiment 1 described above are given the same symbols, and detailed description thereof will be omitted.

[0089] As shown in FIG. 10 (CLOSE) and FIG. 11 (OPEN), the flow control valve 100 of the second embodiment differs from the flow control valve 10 of the first embodiment (see FIG. 2) only in the inclination angle of the annular second flat surface SF2 provided on the small-diameter tip portion 82 of the piston member 80 and the shape of the sphere support member 110.

[0090] 10 and 11, the second plane SF2 rises more steeply so as to face radially outward from the shaft member 70 compared to the first embodiment. As a result, in the second embodiment, the spherical body 41 can be pressed radially outward with a stronger force as the piston member 80 moves toward the other axial side.

[0091] Furthermore, a support body 111 having a third plane SF3 is provided on the other axial side (upper side in FIGS. 10 and 11 ) of the sphere support member 110. Specifically, the support body 111 is formed in a substantially cylindrical shape, and the third plane SF3 is provided on the other axial side (upper side in FIGS. 10 and 11 ) of the support body 111 so as to extend in the circumferential direction of the support body 111. Furthermore, a perpendicular line PL3 (only one line is shown) to the third plane SF3 extends radially inward of the shaft member 70.

[0092] As shown in Figures 10 and 11, the second plane SF2 has a steeper slope than the third plane SF3 with respect to a direction perpendicular to the axial direction of the shaft member 70; in other words, the third plane SF3 has a gentler slope than the second plane SF2.

[0093] The sphere 41 is in point contact with the third plane SF3, and the sphere 41 is capable of sliding against the third plane SF3 while moving in both the axial and radial directions of the shaft member 70 relative to the third plane SF3.

[0094] In this way, the sphere support member 110 is capable of supporting the sphere 41 together with the flange member 73 and the piston member 80. However, as shown in Figure 10, when the flow control valve 100 is closed, a gap MG is formed between the sphere 41 and the flange member 73, similar to the first embodiment.

[0095] Here, as shown by arrow M1 in Fig. 10, when piston member 80 is moved upward by air pressure, sphere 41 comes into point contact with first flat surface SF1 of protrusion 73b, and while pushing up protrusion 73b, slides (slides) into between protrusion 73b and support main body 111, as shown by arrow M2 in Fig. 10. This places sphere 41 in the state shown in Fig. 11, and valve element 60 (see Fig. 2) opens as in the first embodiment.

[0096] The second embodiment formed as described above can also achieve the same effects as the first embodiment.

[0097] In the above-described embodiments, the flow control valves 10, 100 are applied to a semiconductor manufacturing line, but the application is not limited to this. The flow control valves 10, 100 can be used in environments such as clean rooms where air cleanliness is maintained, and can also be applied to, for example, manufacturing lines that handle medical drugs and the like.

[0098] Furthermore, in each of the above-described embodiments, the flow control valves 10, 100 are shown to have a diaphragm-type valve element 60, but the present invention is not limited to this and can be applied to flow control valves having other types of valve elements as long as the valve element is operated by air pressure to open and close the flow path.

[0099] Furthermore, in each of the above-described embodiments, when the valve body 60 is closed (see FIGS. 2 and 10 ), the gap MG is formed between the spherical body 41 and the flange member 73. However, this is not limiting, and the gap MG may be eliminated when the valve body 60 is closed. When the gap MG is eliminated, the spring forces of the first coil springs SP1 and the second coil springs SP2 are set in consideration of the balance between the valve-opening and valve-closing operations of the valve body 60. However, the magnitude relationship between the spring forces of the first coil springs SP1 and the second coil springs SP2 can be set arbitrarily, and the spring force of the first coil springs SP1 may be made greater than the spring force of the second coil springs SP2, or the spring force of the second coil springs SP2 may be made greater than the spring force of the first coil springs SP1.

[0100] In addition, the material, shape, dimensions, number, installation location, etc. of each component in each of the above-mentioned embodiments are arbitrary as long as they can achieve the purpose of this disclosure, and are not limited to each of the above-mentioned embodiments.

[0101] 10...flow rate control valve, 11...housing, 21...upstream flow path (flow path), 22...downstream flow path (flow path), 33...air chamber, 41...sphere, 60...valve body, 70...shaft member, 73b...projection, 80...piston member, 90...sphere support member, 100...flow rate control valve, 110...sphere support member, CS...curved surface, PL2...perpendicular line, PL3...perpendicular line, SF1...first plane, SF2...second plane, SF3...third plane, SP1...first coil spring (spring member), SP2...second coil spring (return spring)

Claims

1. A flow control valve equipped with a valve element that opens and closes a flow path by air pressure, comprising: a housing in which the flow path is provided; a shaft member that is movably accommodated inside the housing, the valve element being provided on one axial side and a protrusion that protrudes radially outward on the other axial side; a piston member that is provided radially outward of the shaft member and is moved toward the other axial side of the shaft member relative to the shaft member by the air pressure; a sphere that is provided between the protrusion along the axial direction of the shaft member and the piston member and is in contact with each of the protrusion and the piston member; and a sphere support member that is provided radially outward of the piston member and supports the sphere; when the piston member is moved toward the other axial side of the shaft member by the air pressure, the sphere moves toward the other axial side of the shaft member and radially outward from the shaft member.

2. A flow control valve as set forth in claim 1, wherein the protrusion has a first plane that extends in a direction perpendicular to the axis of the shaft member and that comes into contact with the sphere, and the piston member has a second plane that extends perpendicularly between the protrusion and the sphere support member and that comes into contact with the sphere.

3. A flow control valve as set forth in claim 2, wherein the sphere support member is formed in a convex shape facing between the protrusion and the piston member, and has a curved surface with which the sphere comes into contact and which guides the movement of the sphere radially outward from the shaft member.

4. A flow control valve according to claim 2, wherein the sphere support member has a third flat surface, the third flat surface having a perpendicular line extending radially inward of the shaft member and with which the sphere comes into contact.

5. A flow control valve as set forth in claim 1, wherein a return spring is disposed on the other axial side of the shaft member to bias the valve element in the valve closing direction.

6. A flow control valve as set forth in claim 5, wherein an air chamber is disposed on one axial side of the shaft member into which the air pressure is introduced to urge the piston member toward the other axial side of the shaft member.

7. A flow control valve as set forth in claim 1, wherein the sphere support member is movable relative to both the protrusion and the piston member, and a spring member is provided between the sphere support member and the piston member in the axial direction of the shaft member, for biasing the sphere support member and the piston member in directions separating them from each other.

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