Fluid control valve

Abstract

In the present invention, a drive shaft 7 comprises a supply channel 71 that supplies compressed air to each of a first cylinder 5 and a second cylinder 6 at a first pressure or a second pressure. The present invention comprises: a first piston 52 which is loaded into the first cylinder 5 and which, when compressed air is supplied to the first cylinder 5 at the first pressure, moves the drive shaft 7 in the separation direction until a valving element 32 moves to a third valve position; and a second piston 62 which is loaded into a second cylinder 6 and that, when compressed air is supplied to the second cylinder 6 at the first pressure, moves the first piston 52 together with the drive shaft 7 in the separation direction until the valving element 32 moves to the third valve position, and when compressed air is supplied to the second cylinder 6 at the second pressure, moves the drive shaft 7 alone in the separation direction until the valving element 32 moves from the third valve position to a second valve position.

Description

Fluid Control Valve

[0001] The present invention relates to a fluid control valve.

[0002] Fluid control valves have been used in semiconductor manufacturing processes. Specifically, fluid control valves are installed between a vacuum chamber in which a wafer is placed and a gas supply source to control the flow rate of process gas used for film deposition processing on the wafer and the flow rate of nitrogen gas used for purging the vacuum chamber.

[0003] A known example of a fluid control valve is the fluid control valve disclosed in Patent Document 1. The fluid control valve disclosed in Patent Document 1 is an air-operated on-off valve that controls the contact and separation movement of a valve element and a valve seat by an operating fluid. Specifically, the valve element is operated to a valve closed position (referred to as a first opening) where the valve element contacts the valve seat, a maximum valve open position (referred to as a second opening) where the valve element is farthest from the valve seat, and an intermediate position (referred to as a third opening) between these positions, as follows:

[0004] The fluid control valve disclosed in Patent Document 1 is a normally closed valve, and when no operating fluid is supplied, the valve element is positioned at a first opening in which it abuts against the valve seat.

[0005] Furthermore, the fluid control valve disclosed in Patent Document 1 includes a first pressurized chamber in which a first piston is installed, and a first control port that supplies operating fluid to the first pressurized chamber. When operating fluid is supplied from the first control port to the first pressurized chamber, the first piston operates and the valve body is positioned at a second opening.

[0006] Furthermore, the fluid control valve disclosed in Patent Document 1 includes a second pressurized chamber in which a second piston is installed, and a second control port that supplies operating fluid to the second pressurized chamber. When operating fluid is supplied from the second control port to the second pressurized chamber, the second piston operates and the valve body is positioned at a third opening.

[0007] In other words, the fluid control valve disclosed in Patent Document 1 can control the opening degree in two stages, the second opening degree and the third opening degree, depending on whether the operating fluid is supplied to the first control port via the first control port or the operating fluid is supplied to the second pressurized chamber via the second control port.

[0008] Japanese Patent Application Publication No. 8-170755

[0009] In the above-described fluid control valve, the first control port for positioning the valve element at the second opening and the second control port for positioning the valve element at the third opening are separately provided, and therefore, piping for supplying the operating fluid must be connected to each port, requiring piping space for the respective ports, which may hinder the density of semiconductor manufacturing equipment.

[0010] The present invention has been made in consideration of the above problems, and has an object to provide a fluid control valve that is capable of two-stage opening control and that can reduce the piping space for supplying the operating fluid.

[0011] In order to solve the above problems, a fluid control valve according to one aspect of the present invention has the following configuration.

[0012] (1) In a fluid control valve including a valve seat, a valve element that performs contact and separation movement between a first opening in which the valve element contacts the valve seat and a second opening in which the valve element is most distant from the valve seat, a drive shaft for performing the contact and separation movement of the valve element, a cylinder portion through which the drive shaft is inserted along the direction of the contact and separation movement, a piston that is loaded into the cylinder portion and receives fluid pressure of an operating fluid supplied to the cylinder portion to operate the drive shaft in the separation direction in which the valve element separates, and a biasing member that applies a biasing force to the piston in a contact direction that is the opposite direction to the separation direction, the cylinder portion includes a first cylinder and a second cylinder that are stacked along the axial direction of the drive shaft, and the drive shaft supplies the operating fluid to each of the first cylinder and the second cylinder at a first pressure or a second pressure. the piston comprises a first piston that is loaded in the first cylinder and that, when the operating fluid is supplied to the first cylinder at the first pressure, moves the drive shaft in the separating direction from the first opening until the valve element moves from the first opening to a third opening between the first opening and the second opening; and a second piston that is loaded in the second cylinder and, when the operating fluid is supplied to the second cylinder at the first pressure, moves the drive shaft in the separating direction together with the first piston until the valve element moves from the first opening to the third opening, and, when the operating fluid is supplied to the second cylinder at the second pressure, moves the drive shaft in the separating direction alone until the valve element moves from the third opening to the second opening.

[0013] (2) In the fluid control valve described in (1), it is preferable that the first cylinder has a first regulating portion that abuts against the first piston from the side in the separation direction and regulates the valve body to the third opening degree, and the second cylinder has a second regulating portion that abuts against the second piston from the side in the separation direction and regulates the valve body to the second opening degree.

[0014] (3) In the fluid control valve described in (2), it is preferable that the first regulating portion is formed at the end of the second cylinder on the side of the first cylinder, the second cylinder is screwed to the first cylinder so that its position in the axial direction can be adjusted, and the position of the first regulating portion can be adjusted by adjusting the position of the second cylinder, and the second regulating portion is screwed to the second cylinder on the side of the second cylinder opposite the side of the first cylinder so that its position in the axial direction can be adjusted.

[0015] (4) In the fluid control valve described in any one of (1) to (3), it is preferable that the pressure-receiving area of ​​the first piston is larger than the pressure-receiving area of ​​the second piston.

[0016] The fluid control valve includes a first cylinder with a first piston and a second cylinder with a second piston, stacked along the axial direction of the drive shaft, wherein the first piston, when operating fluid is supplied to the first cylinder at a first pressure, moves the drive shaft in the separating direction until the valve element moves from the first opening to a third opening, and the second piston, when operating fluid is supplied to the second cylinder at the first pressure, moves the drive shaft together with the first piston in the separating direction until the valve element moves from the first opening to the third opening, and when operating fluid is supplied to the second cylinder at a second pressure, moves the drive shaft independently in the separating direction until the valve element moves from the third opening to the second opening. Thus, the opening degree of the valve element can be controlled in two stages, the second opening degree and the third opening degree, depending on whether the operating fluid is supplied at the first pressure or the second pressure. Furthermore, the supply of the operating fluid at the first pressure or the second pressure to the first cylinder or the second cylinder is performed through a supply passage provided in the drive shaft, so that the piping for supplying the operating fluid only needs to be connected to the supply passage, thereby reducing the piping space.

[0017] According to the fluid control valve of the present invention, two-stage opening control is possible, and the piping space for supplying the operating fluid can be reduced.

[0018] FIG. 1 is a cross-sectional view of the fluid control valve according to the present embodiment, showing a state in which the diaphragm member is at a first opening degree (valve closed state of the fluid control valve); FIG. 2 is a cross-sectional view of the fluid control valve according to the present embodiment, showing a state in which the diaphragm member is at a third opening degree; FIG. 3 is a cross-sectional view of the fluid control valve according to the present embodiment, showing a state in which the diaphragm member is at a second opening degree (maximum valve open state of the fluid control valve); FIG. 4 is a cross-sectional view of a fluid control valve according to a modified example; FIG. 5 is a cross-sectional view of a fluid control valve according to a modified example.

[0019] An embodiment of a fluid control valve according to the present invention will be described in detail with reference to the drawings. Note that the drawings used in the description are simplified for the purpose of explanation and do not accurately represent the shape, dimensions, etc.

[0020] (Configuration of the Fluid Control Valve) The configuration of the fluid control valve 1 according to this embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the fluid control valve 1 according to this embodiment, showing a state in which the diaphragm member 34 is at a first opening degree (a valve-closed state of the fluid control valve 1). FIG. 2 is a cross-sectional view of the fluid control valve 1 according to this embodiment, showing a state in which the diaphragm member 34 is at a third opening degree. FIG. 3 is a cross-sectional view of the fluid control valve 1 according to this embodiment, showing a state in which the diaphragm member 34 is at a second opening degree (a fully open state of the fluid control valve 1). The up-down direction in FIGS. 1 to 3 corresponds to the direction in which the diaphragm member 34 moves toward and away from a valve seat 33, which will be described later. The upper side in FIGS. 1 to 3 corresponds to the moving-away direction, and the lower side corresponds to the moving-away direction.

[0021] The fluid control valve 1 is a gas valve used in semiconductor manufacturing processes. More specifically, it is installed between a vacuum chamber in which a wafer is placed and a gas supply source, and is used to control the flow rate of a process gas for performing a film formation process on the wafer and the flow rate of nitrogen gas for purging the vacuum chamber. The film formation process on the wafer is performed by, for example, atomic layer deposition (ALD).

[0022] The fluid control valve 1 is a normally closed type air operated on-off valve, and as shown in FIG. 1, comprises a cylinder portion 2, a valve portion 3, and a spring portion 4.

[0023] (Regarding the Cylinder Unit) First, we will explain the cylinder unit 2. The cylinder unit 2 is an air cylinder that is driven by compressed air (an example of an operating fluid) supplied from compressed air supply sources (first supply source 8, second supply source 9). The cylinder unit 2 also includes a first cylinder 5 and a second cylinder 6 that are stacked one on top of the other.

[0024] The first cylinder 5 has a first cylinder housing 51 and a first piston 52 as main components.

[0025] The first cylinder housing 51 is formed in a cylindrical shape with a bottom, including an opening 53 on the second cylinder 6 side and a bottom 54 on the opposite side, and includes a first piston chamber 55 as a cylindrical space inside. A first piston 52 formed in a disk shape is loaded in the first piston chamber 55, and the first piston 52 divides the first piston chamber 55 into an upper chamber 551 on the opening 53 side and a lower chamber 552 on the bottom 54 side.

[0026] The first piston 52 is slidable in the up-down direction in the drawing within the first piston chamber 55. More specifically, the first piston 52 is slidable between a lower limit position and an upper limit position, and the lower limit position is a position where the first piston 52 abuts against the bottom of the first piston chamber 55 as shown in Fig. 1, and the upper limit position is a position where the first piston 52 abuts against a first restricting portion 68 (described later) as shown in Figs. 2 and 3.

[0027] In addition, the first cylinder housing 51 has a female thread portion 56 on the end of the inner surface of the opening 53 on the second cylinder 6 side, and the second cylinder 6 is connected to the first cylinder 5 by being screwed into the female thread portion 56.

[0028] The second cylinder 6 mainly includes a second cylinder housing 61, a second piston 62, a restricting member 63, and a first compression coil spring 64 (an example of a biasing member).

[0029] The second cylinder housing 61 is formed in a cylindrical shape, and of its two axial ends (the up-down direction in the drawing), the end on the first cylinder 5 side is closed by a bottom 65, and the opposite end is closed by a head 66. The second cylinder housing 61 also has a second piston chamber 67 as a cylindrical space inside. A second piston 62 formed in a disk shape is loaded in the second piston chamber 67, and the second piston 62 divides the second piston chamber 67 into an upper chamber 671 on the head 66 side and a lower chamber 672 on the bottom 65 side.

[0030] The second piston 62 is slidable in the up-down direction in the figure within the second piston chamber 67. More specifically, it is slidable between a lower limit position and an upper limit position, the lower limit position being a position where the second piston 62 abuts against the bottom of the second piston chamber 67 as shown in Fig. 1, and the upper limit position being a position where the second piston 62 abuts against a second restricting portion 632 (described later) as shown in Fig. 3.

[0031] A first compression coil spring 64 is housed in the upper chamber 671 of the second piston chamber 67. The first compression coil spring 64 is compressed by the head portion 66 and the second piston 62, and therefore constantly applies a biasing force to the second piston 62 in the contact direction (downward in the figure).

[0032] The second cylinder housing 61 has a male thread 651 on the outer peripheral surface of the bottom 65, which is threadedly engaged with the female thread 56 of the first cylinder 5 as described above. As a result, the bottom 65 of the second cylinder housing 61 closes the first piston chamber 55 and forms part of the first cylinder 5. Note that this threaded engagement positions the first cylinder 5 and the second cylinder 6 coaxially. In addition, a first restricting portion 68 protrudes from the lower end surface of the second cylinder housing 61 facing the first piston 52. The first restricting portion 68 is used to determine the upper limit position of the first piston 52. In other words, the position where the first piston 52 abuts against the first restricting portion 68 is the upper limit position of the first piston 52.

[0033] Because the second cylinder 6 is threadedly engaged with the first cylinder 5, its axial position relative to the first cylinder 5 can be continuously adjusted by adjusting the depth to which it is threaded into the first cylinder 5. This means that the distance D1 between the first piston 52 and the first restricting portion 68 when the first piston 52 is at its lowest position (i.e., the stroke between the lowest and highest positions of the first piston 52) can be adjusted. The stroke of the first piston 52 will be described in detail later.

[0034] Furthermore, the second cylinder housing 61 has a female thread portion 69 that penetrates the head 66 in the axial direction, and the restricting member 63 is screwed onto this female thread portion 69. The restricting member 63 is a substantially cylindrical member, and has an insertion hole 634 through which the drive shaft 7 (described later) can be inserted. In addition, a male thread portion 631 is provided on the outer circumferential surface of the restricting member 63, and the screw depth of the restricting member 63 into the second cylinder housing 61 can be adjusted.

[0035] The restricting member 63 is inserted into the second piston chamber 67 by being screwed into the second cylinder housing 61, and a second restricting portion 632 protrudes from the lower end surface facing the second piston 62. The second restricting portion 632 is used to determine the upper limit position of the second piston 62. In other words, the position where the second piston 62 abuts against the second restricting portion 632 is the upper limit position of the first piston 52.

[0036] By adjusting the screw depth of the restricting member 63 into the second cylinder housing 61, it is possible to adjust the distance D2 between the second piston 62 and the second restricting portion 632 when the second piston 62 is at its lowest position (i.e., the stroke between the lowest and highest positions of the second piston 62). The stroke of the second piston 62 will be described in detail later.

[0037] A first photoelectric sensor 21 for detecting the position of the first piston 52 and a second photoelectric sensor 22 for detecting the position of the second piston 62 are attached to the end face (top end face in the figure) of the second cylinder housing 61 on the head 66 side. The first photoelectric sensor 21 and the second photoelectric sensor 22 are general photoelectric sensors that detect the position of a detection target by irradiating light onto the detection target and receiving light reflected from the detection target. Because the diameter of the first piston 52 is larger than that of the second piston 62, the first photoelectric sensor 21 is positioned radially outward from the outermost diameter portion of the second piston 62. As a result, the first photoelectric sensor 21 can detect the position of the first piston 52 by irradiating light onto the first piston 52 in the first piston chamber 55 through the second cylinder housing 61 and receiving light reflected from the first piston 52. The second photoelectric sensor 22 is located more inward than the first photoelectric sensor 21, and is able to detect the position of the second piston 62 by irradiating light onto the second piston 62 in the second piston chamber 67 through the head 66 and receiving reflected light from the second piston 62.

[0038] A drive shaft 7 is inserted through the cylinder section 2 along the axial direction of the first cylinder 5 and the second cylinder 6. Furthermore, inside the cylinder section 2, the drive shaft 7 is not coupled to the first piston 52 or the second piston 62, but is slidably inserted through the center of each piston 52, 62.

[0039] The drive shaft 7 is cylindrical. Its axial direction is parallel to the vertical direction in FIG. 1 and coincides with the direction in which the diaphragm member 34 moves toward and away from the valve seat 33. Of both axial ends of the drive shaft 7, the end inserted into the restricting member 63 (the upper end in the figure) is connected to a pipe 10 extending from a compressed air supply source via, for example, a quick joint. This allows the cylinder 2 to receive a supply of compressed air. More specifically, the pipe 10 connected to the drive shaft 7 branches, and a first supply source 8 and a second supply source 9 are connected in parallel. The first supply source 8 and the second supply source 9 supply compressed air at different pressures. The first supply source 8 supplies compressed air at a first pressure (e.g., 0.4 MPa) to the cylinder 2, and the second supply source 9 supplies compressed air at a second pressure (e.g., 0.6 MPa), which is higher than the first pressure, to the cylinder 2. A switching valve (not shown) provided on the piping 10 makes it possible to switch between a state in which compressed air is supplied from the first supply source 8 and a state in which compressed air is supplied from the second supply source 9.

[0040] The drive shaft 7 has a supply passage 71 on its axis for flowing compressed air. The supply passage 71 has a first branch passage 711 that communicates with the lower chamber 552 of the first piston chamber 55 and a second branch passage 712 that communicates with the lower chamber 672 of the second piston chamber 67. Therefore, when compressed air is supplied to the supply passage 71, the compressed air flows into the lower chamber 552 of the first piston chamber 55 via the first branch passage 711, and also flows into the lower chamber 672 of the second piston chamber 67 via the second branch passage 712. This causes the first piston 52 and the second piston 62 to slide. Specifically, when compressed air flows into the lower chamber 552 of the first piston chamber 55, the pressure in the lower chamber 552 increases, causing the first piston 52 to slide toward its upper limit position. Furthermore, when compressed air flows into the lower chamber 672 of the second piston chamber 67, the pressure in the lower chamber 672 increases, causing the second piston 62 to slide toward the upper limit position. Here, it is desirable that the area of ​​the first piston 52 facing the lower chamber 552 (i.e., the pressure-receiving area that receives the pressure of the compressed air) be larger than the area of ​​the second piston 62 facing the lower chamber 672 (pressure-receiving area). In this embodiment, the pressure-receiving area of ​​the first piston 52 is set to 1.5 times the pressure-receiving area of ​​the second piston 62.

[0041] The drive shaft 7 has a first engagement portion 72 protruding in the radial direction of the drive shaft 7 on a portion of its outer circumferential surface facing the upper chamber 551 of the first piston chamber 55. When the first piston 52 slides from the lower limit position to the upper limit position, the first engagement portion 72 abuts against the first engagement portion 72, thereby pushing the drive shaft 7 upward in the separation direction against the biasing forces of the first compression coil spring 64 and a second compression coil spring 42 (described later) in the abutment direction. Furthermore, the drive shaft 7 has a second engagement portion 73 protruding in the radial direction of the drive shaft 7 on a portion of its outer circumferential surface facing the upper chamber 671 of the second piston chamber 67. When the second piston 62 slides from the lower limit position to the upper limit position, the second engagement portion 73 abuts against the second engagement portion 73, thereby pushing the drive shaft 7 upward in the separation direction against the biasing forces of the first compression coil spring 64 and a second compression coil spring 42 (described later) in the abutment direction.

[0042] (Spring Portion) Next, a description will be given of the spring portion 4. The spring portion 4 includes a housing 41 and a second compression coil spring 42 (an example of a biasing member).

[0043] The end of the drive shaft 7 on the spring portion 4 side (the lower end in FIG. 1 ) protrudes from the cylinder portion 2 and extends into the housing 41. A spring retainer 74 protruding in the radial direction of the drive shaft 7 is provided at the tip of the drive shaft 7 within the housing 41. A second compression coil spring 42 is disposed coaxially with the drive shaft 7 within the housing 41. The second compression coil spring 42 is compressed by the spring retainer 74 and a ceiling portion 411 within the housing 41, thereby constantly applying a biasing force to the drive shaft 7 in the contact direction (downward in the figure). When the first engagement portion 72 of the drive shaft 7 abuts against the first piston 52, the second compression coil spring 42 also applies a biasing force to the first piston 52 in the contact direction. When the second engagement portion 73 of the drive shaft 7 abuts against the second piston 62, the second compression coil spring 42 also applies a biasing force to the second piston 62 in the contact direction.

[0044] (Valve Section) Next, a description will be given of the valve section 3. The valve section 3 includes a body 31, a stem 32, a valve seat 33, and a diaphragm member 34 (an example of a valve body).

[0045] A valve chamber 311 is formed in the end face of the body 31 on the spring portion 4 side. Control fluid flows into the valve chamber 311 through a valve hole 312 provided in the center of the bottom of the valve chamber 311. An annular valve seat 33 is fixed to the bottom face of the valve chamber 311 on the outer circumferential side of the valve hole 312 and coaxially with the valve hole 312. Furthermore, an output flow path 314 is formed in the valve chamber 311 radially outward of the valve seat 33. This output flow path 314 is used to output the control fluid from the valve chamber 311 to the outside of the fluid control valve 1.

[0046] The stem 32 is made of, for example, stainless steel and is formed in a generally cylindrical shape, with its upper end surface facing the drive shaft 7 abutting against the drive shaft 7 and its lower end surface facing the diaphragm member 34 abutting against the diaphragm member 34. The stem 32 is held by a holder 35 so as to be movable up and down.

[0047] The diaphragm member 34 is made of, for example, a Ni alloy, and in its natural state is formed into a spherical crown shape that bulges toward the drive shaft 7. The outer peripheral edge of the diaphragm member 34 is clamped and fixed from above and below between a holder 35 and the body 31 within the valve portion 3.

[0048] The surface of the diaphragm member 34 facing the stem 32 abuts against the stem 32. When the drive shaft 7 moves in the abutment direction and pushes the stem 32 down in the abutment direction, the diaphragm member 34 is elastically deformed in the abutment direction by the stem 32. When the drive shaft 7 moves in the separation direction while in this elastically deformed state, the diaphragm member 34 pushes the stem 32 up in the separation direction by its self-returning force, returning to its original spherical crown shape. As described above, the diaphragm member 34 elastically deforms in response to the advancement and retreat of the drive shaft 7, causing the diaphragm member 34 to move between abutting and separating from the valve seat 33. More specifically, the diaphragm member 34 moves between a first opening (position shown in FIG. 1 ) in which the diaphragm member 34 abuts against the valve seat 33, a second opening (position shown in FIG. 3 ) in which the diaphragm member 34 is farthest from the valve seat 33, and a third opening (position shown in FIG. 2 ) between the first and second openings. The state in which the diaphragm member 34 is at the first opening degree means that the fluid control valve 1 is in a valve closed state, and the flow of the control fluid is blocked. The state in which the diaphragm member 34 is at the second opening degree means that the fluid control valve 1 is in a maximum valve open state, and the flow rate of the control fluid is at its maximum.

[0049] The valve seat 33 is made of, for example, a heat-resistant material such as polyimide (PI) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). The end face of the valve seat 33 facing the diaphragm member 34 is the contact surface with which the diaphragm member 34 comes into contact.

[0050] (Strokes of the First and Second Pistons) The stroke (distance D1) of the first piston 52 is set to be shorter than the stroke (distance D2) of the second piston 62. Therefore, the first piston 52 and the second piston 62 together push up the drive shaft 7 until the drive shaft 7 is pushed up by the distance D1, i.e., until the first piston 52 abuts against the first restricting portion 68. After the drive shaft 7 is pushed up by the distance D1, i.e., after the first piston 52 abuts against the first restricting portion 68, the second piston 62 alone pushes up the drive shaft 7 until it abuts against the second restricting portion 632. At this time, because the drive shaft 7 is slidably inserted relative to the first piston 52, the drive shaft 7 is pushed up in the separating direction by the second piston 62, leaving the first piston 52 at its upper limit position.

[0051] The diaphragm member 34 operates between a first opening (position shown in FIG. 1 ) at which it abuts against the valve seat 33, a second opening (position shown in FIG. 3 ) at which it is farthest from the valve seat 33, and a third opening (position shown in FIG. 2 ) between the first and second openings, where the third opening corresponds to the stroke (distance D1) of the first piston 52, and the second opening corresponds to the stroke (distance D2) of the second piston 62. In other words, the third opening of the diaphragm member 34 occurs when the diaphragm member 34 is spaced from the valve seat 33 by the distance D1 that the drive shaft 7 has been pushed up, and the second opening of the diaphragm member 34 occurs when the diaphragm member 34 is spaced from the valve seat 33 by the distance D2 that the drive shaft 7 has been pushed up. The distance D1 can be adjusted continuously by adjusting the screw depth of the second cylinder 6 into the first cylinder 5, thereby enabling continuous adjustment of the third degree of opening. Furthermore, the distance D2 can be adjusted continuously by adjusting the screw depth of the regulating member 63 into the second cylinder 6, thereby enabling continuous adjustment of the second degree of opening. Therefore, by adjusting the distance D1, it is possible to finely adjust the flow rate of the controlled fluid when the diaphragm member 34 is at the second degree of opening (i.e., it is possible to finely adjust the maximum flow rate of the controlled fluid), and by adjusting the distance D1, it is possible to finely adjust the flow rate of the controlled fluid when the diaphragm member 34 is at the third degree of opening.

[0052] The adjustable ranges of the distances D1 and D2 are set in consideration of the elastic forces of the first compression coil spring 64 and the second compression coil spring 42 and the pressure-receiving areas of the first piston 52 and the second piston 62. Specifically, the distance D1 at which the diaphragm member 34 is positioned at the third opening is the distance at which both the first piston 52 and the second piston 62 push up the drive shaft 7. Therefore, in consideration of the pressure-receiving areas of the first piston 52 and the second piston 62 and the elastic forces of the first compression coil spring 64 and the second compression coil spring 42, the distance D1 can be adjusted within the stroke range that allows the drive shaft 7 to be pushed up with the first pressure (0.4 MPa). Furthermore, the distance D2 for the diaphragm member 34 to be positioned at the second opening is the distance at which the second piston 62 alone pushes up the drive shaft 7, and therefore can be adjusted to a value greater than the distance D1 and within the stroke range at which the drive shaft 7 can be pushed up with the second pressure (0.6 MPa), taking into account the pressure-receiving area of ​​the second piston 62 and the elastic forces of the first compression coil spring 64 and the second compression coil spring 42.

[0053] Since the distances D1 and D2 are set as described above, when compressed air at the first pressure (0.4 MPa) is supplied to the cylinder portion 2, the first piston 52 can be operated until it abuts against the first restricting portion 68, and the diaphragm member 34 can be maintained at the third opening degree. Furthermore, when compressed air at the second pressure (0.6 MPa) is supplied to the cylinder portion 2, the second piston 62 can be operated until it abuts against the second restricting portion 632, and the diaphragm member 34 can be maintained at the second opening degree.

[0054] (Operation of the Fluid Control Valve) The fluid control valve 1 configured as above performs the valve opening and closing operations as follows.

[0055] First, the valve opening operation will be described. The valve opening operation includes a case in which the diaphragm member 34 is moved to the third opening degree from a state in which the fluid control valve 1 is in the valve closed state, and a case in which the diaphragm member 34 is moved to the second opening degree.

[0056] When the diaphragm member 34 is operated to the third opening, the fluid control valve 1 operates as follows. Since the fluid control valve 1 is of a normally closed type, when compressed air is not supplied to the cylinder portion 2, the drive shaft 7 is pressed down in the abutting direction by the biasing force of the second compression coil spring 42. Therefore, as shown in FIG. 1 , the diaphragm member 34 is elastically deformed by the stem 32 and is in a state of the first opening in which it abuts against the valve seat 33. In other words, the fluid control valve 1 is in a valve-closed state.

[0057] In this state, compressed air at a first pressure (0.4 MPa) is supplied to the cylinder portion 2 using the first supply source 8. This increases the pressure in the lower chambers 552, 672, causing the first piston 52 and the second piston 62 to slide away from each other. Accordingly, the drive shaft 7 is driven in the same direction against the biasing forces of the first compression coil spring 64 and the second compression coil spring 42. As the drive shaft 7 is driven in the separation direction, the diaphragm member 34 moves in the same direction due to its self-returning force, and moves away from the valve seat 33 while pushing up the stem 32.

[0058] 2, when the drive shaft 7 is pushed up by the distance D1, the first piston 52 abuts against the first restricting portion 68. At this time, a gap equal to the distance D2 minus the distance D1 remains between the second piston 62 and the second restricting portion 632, and although the second piston 62 has not reached its upper limit position, the compressed air at the first pressure (0.4 MPa) supplied from the first supply source 8 cannot push up the second piston 62 and the drive shaft 7 any further against the biasing forces of the first compression coil spring 64 and the second compression coil spring 42. Therefore, the diaphragm member 34 is restricted in a state in which the diaphragm member 34 is separated from the valve seat 33 by the distance D1 by which the drive shaft 7 is pushed up, i.e., in a state in which the third opening is achieved. Whether the diaphragm member 34 has been operated to the third opening degree can be determined by detecting the positions of the first piston 52 and the second piston 62 using the first photoelectric sensor 21 and the second photoelectric sensor 22.

[0059] When the diaphragm member 34 is operated to the second opening degree, the fluid control valve 1 operates as follows.

[0060] To move the diaphragm member 34 from the third opening to the second opening, compressed air at the first pressure (0.4 MPa) is supplied as described above. With the diaphragm member 34 restricted to the third opening, the compressed air supply source is switched from the first supply source 8 to the second supply source 9, and compressed air at the second pressure (0.6 MPa) is supplied to the cylinder portion 2. While the first restricting portion 68 restricts the first piston 52 from sliding further in the separation direction, a gap equal to the distance D2 minus the distance D1 exists between the second piston 62 and the second restricting portion 632. Therefore, the second piston 62 independently pushes the drive shaft 7 in the separation direction against the biasing forces of the first compression coil spring 64 and the second compression coil spring 42. As a result, the diaphragm member 34 moves further in the separation direction from the third opening due to its self-returning force. When the second piston 62 abuts against the second restricting portion 632, the diaphragm member 34 is restricted to the second opening degree.

[0061] When the diaphragm member 34 is moved from the first opening degree to the second opening degree, compressed air at the second pressure (0.4 MPa) is supplied to the cylinder portion 2 from the second supply source 9 rather than switching from the first supply source 8 to the second supply source 9. Even in this case, both the first piston 52 and the second piston 62 push up the drive shaft 7 until the drive shaft 7 moves by the distance D1. After the drive shaft 7 moves by the distance D1, the second piston 62 alone pushes up the drive shaft 7. Then, the second piston 62 abuts against the second restricting portion 632, restricting the diaphragm member 34 to the second opening degree. Whether the diaphragm member 34 has been moved to the second opening degree can be determined by detecting the positions of the first piston 52 and the second piston 62 using the first photoelectric sensor 21 and the second photoelectric sensor 22.

[0062] Next, the valve closing operation will be described. When the fluid control valve 1 is in the valve open state (for example, when the diaphragm member 34 is at the third or second opening degree), if the supply of compressed air to the cylinder portion 2 is stopped, the second compression coil spring 42 drives the drive shaft 7 in the abutting direction, and the diaphragm member 34 is elastically deformed by the stem 32 and abuts against the valve seat 33. That is, the diaphragm member 34 is operated to the first opening degree. As a result, the fluid control valve 1 is in the valve closed state. Whether the diaphragm member 34 has been operated to the first opening degree can be determined by detecting the positions of the first piston 52 and the second piston 62 using the first photoelectric sensor 21 and the second photoelectric sensor 22. Also, at the same time that the diaphragm member 34 is operated, the first piston 52 is pushed down to its lower limit position by the first engagement portion 72 of the drive shaft 7, which is driven in the abutment direction, and the second piston 62 is pushed down to its lower limit position by the first compression coil spring 64.

[0063] When the first piston 52 is pushed down to the lowest position, the compressed air that was supplied to the lower chamber 552 is discharged to the outside of the cylinder portion 2 via the first branch path 711 and the supply path 71. When the second piston 62 is pushed down to the lowest position, the compressed air that was supplied to the lower chamber 672 is discharged to the outside of the cylinder portion 2 via the second branch path 712 and the supply path 71.

[0064] In the valve closed state, a seal is formed between the diaphragm member 34 and the valve seat 33, blocking the flow of control fluid from the valve hole 312 to the valve chamber 311. This seal is maintained by the biasing force of the second compression coil spring 42, which is applied to the drive shaft 7, in the contact direction.

[0065] (Operation and Effect) As described above, the fluid control valve 1 according to this embodiment comprises: (1) a valve seat 33, a valve element (e.g., diaphragm member 34) that performs contact and separation movement between a first opening in which the valve element contacts the valve seat 33 and a second opening in which the valve element is most separated from the valve seat 33, a drive shaft 7 for performing the contact and separation movement of the valve element (diaphragm member 34), a cylinder portion 2 into which the drive shaft 7 is inserted along the direction of the contact and separation movement, and a cylinder portion 2 that is loaded into the cylinder portion 2 and receives the fluid pressure of the operating fluid (compressed air) supplied to the cylinder portion 2, thereby moving the drive shaft 7 in a separation direction (upward in FIG. 1 ) in which the valve element (diaphragm member 34) separates from the drive shaft 7. In the fluid control valve 1, the fluid control valve 1 includes pistons (first piston 52, second piston 62) that operate in a contact direction (downward direction in FIG. 1 ) opposite to the separation direction, and biasing members (first compression coil spring 64, second compression coil spring 42) that apply a biasing force to the pistons (first piston 52, second piston 62) in a contact direction (downward direction in FIG. 1 ) that is opposite to the separation direction. The cylinder section 2 includes a first cylinder 5 and a second cylinder 6 that are stacked along the axial direction of a drive shaft 7 (up and down direction in FIG. 1 ). The drive shaft 7 is provided with a first cylinder 5 and a second cylinder 6 that are operated. The valve element (diaphragm member 34) is configured to move the drive shaft 7 in the separating direction (upward in FIG. 1 ) from the first opening to a third opening between the first opening and the second opening, when the operating fluid (compressed air) is supplied to the first cylinder 5 at the first pressure (0.4 MPa). The valve element (diaphragm member 34) is configured to move the drive shaft 7 in the separating direction (upward in FIG. 1 ). The valve element (diaphragm member 34) is configured to move from the first opening to a third opening between the first opening and the second opening. The valve element (diaphragm member 34) is configured to move from the first opening to the third ... a) which, when operating fluid (compressed air) is supplied to the second cylinder 6 at a first pressure (0.4 MPa), moves the drive shaft 7 together with the first piston 52 in the separating direction (upward in FIG. 1 ) until the valve element (diaphragm member 34) moves from the first opening to the third opening, and a second piston 62 which, when operating fluid (compressed air) is supplied to the second cylinder 6 at a second pressure (0.6 MPa), moves the drive shaft 7 alone in the separating direction (upward in FIG. 1 ) until the valve element (diaphragm member 34) moves from the third opening to the second opening.

[0066] (2) In the fluid control valve 1 described in (1), it is preferable that the first cylinder 5 has a first regulating portion 68 that abuts against the first piston 52 from the side in the separation direction (upward in FIG. 1) and regulates the valve body (diaphragm member 34) to the third opening degree, and the second cylinder 6 has a second regulating portion 632 that abuts against the second piston 62 from the side in the separation direction (upward in FIG. 1) and regulates the valve body (diaphragm member 34) to the second opening degree.

[0067] (3) In the fluid control valve described in (2), it is preferable that the first regulating portion 68 is formed at the end of the second cylinder 6 on the side of the first cylinder 5, the second cylinder 6 is screwed to the first cylinder 5 so that its position in the axial direction (vertical direction in FIG. 1) can be adjusted, and the axial position of the first regulating portion 68 can be adjusted by adjusting the position of the second cylinder 6, and the second regulating portion 632 is screwed to the second cylinder 6 on the side opposite to the first cylinder 5 side so that its position in the axial direction (vertical direction in FIG. 1) can be adjusted.

[0068] (4) In the fluid control valve described in any one of (1) to (3), it is preferable that the pressure-receiving area of ​​the first piston 52 is larger than the pressure-receiving area of ​​the second piston 62 (for example, 1.5 times larger).

[0069] The fluid control valve 1 described above includes a first cylinder 5 loaded with a first piston 52 and a second cylinder 6 loaded with a second piston 62, which are stacked along the axial direction of a drive shaft 7. When an operating fluid (compressed air) is supplied to the first cylinder 5 at a first pressure (0.4 MPa), the first piston 52 moves the drive shaft 7 in the separating direction until the valve element (diaphragm member 34) moves from the first opening degree to the third opening degree. When the operating fluid (compressed air) is supplied to the second cylinder 6 at a first pressure (0.4 MPa), the drive shaft 7 moves together with the first piston 52 in the separating direction until the valve element (diaphragm member 34) is positioned from the first opening to the third opening, and when the operating fluid (compressed air) is supplied to the second cylinder 6 at a second pressure (0.6 MPa), the drive shaft 7 moves independently in the separating direction until the valve element (diaphragm member 34) moves from the third opening to the second opening. Therefore, the opening of the valve element (diaphragm member 34) can be controlled in two stages, the second opening and the third opening, depending on whether the operating fluid (compressed air) is supplied at the first pressure (0.4 MPa) or the second pressure (0.6 MPa). Furthermore, the supply of the operating fluid (compressed air) at the first pressure (0.4 MPa) or the second pressure (0.6 MPa) to the first cylinder 5 and the second cylinder 6 is performed through a supply path 71 provided in the drive shaft 7. Therefore, the piping 10 for supplying the operating fluid only needs to be connected to the supply path 71, which makes it possible to reduce the piping space.

[0070] The second opening degree (adjustment of distance D2) can be adjusted by adjusting the screw-in depth of the second cylinder 6, and the third opening degree (adjustment of distance D1) can be adjusted by adjusting the screw-in depth of the restricting member 63. In other words, the second opening degree (adjustment of distance D2) and the third opening degree (adjustment of distance D1) can be adjusted from above the fluid control valve 1, so there is no need to ensure space for adjustment on the side of the fluid control valve 1. This leads to a reduction in the installation space (footprint) of the fluid control valve 1.

[0071] In addition, the photoelectric sensors 21, 22 for detecting the positions of the first piston 52 and the second piston 62 (the opening degree of the diaphragm member 34) are arranged together on the upper end surface of the second cylinder 6, which leads to a reduction in the installation space (footprint) of the fluid control valve 1.

[0072] (Regarding Modified Examples of the Fluid Control Valve) A modified example of the fluid control valve 100 will be described. In the fluid control valve 1, the pressure-receiving area of ​​the first piston 52 loaded in the first cylinder 5 is set to be larger than the pressure-receiving area of ​​the second piston 62 loaded in the second cylinder 6, but as in the fluid control valve 100 described below, the first piston may be divided into a piston 122 and a piston 123 to increase the pressure-receiving area.

[0073] The fluid control valve 100 is a normally closed type air operated on-off valve, and as shown in Fig. 4, includes a cylinder portion 11, a valve portion 3, and a spring portion 4. The configurations of the valve portion 3 and the spring portion 4 are the same as those of the fluid control valve 1, so differences from the fluid control valve 1, such as the cylinder portion 11 and the drive shaft 7 inserted into the cylinder portion 11, will be described below.

[0074] The cylinder unit 11 is an air cylinder that is driven by compressed air (an example of an operating fluid) supplied from compressed air supply sources (first supply source 8, second supply source 9). The cylinder unit 11 also includes a first cylinder 12 and a second cylinder 6 that are stacked one on top of the other.

[0075] The first cylinder 12 mainly includes a first cylinder housing 121 and pistons 122 and 123 (examples of first pistons).

[0076] The first cylinder housing 121 is formed in a bottomed cylindrical shape with an opening 124 on the second cylinder 6 side and a bottom 125 on the opposite side. Inside, a piston chamber 126 on the bottom 125 side and a piston chamber 127 on the opening 124 side are provided as cylindrical spaces, coaxially aligned. Disc-shaped pistons 122 and 123 are installed in the piston chambers 126 and 127, respectively. The piston 122 divides the piston chamber 126 into an upper chamber 1261 on the opening 124 side and a lower chamber 1262 on the bottom 125 side, while the piston 123 divides the piston chamber 127 into an upper chamber 1271 on the opening 124 side and a lower chamber 1272 on the bottom 125 side. These pistons 122 and 123 have the same diameter as the second piston 62 installed in the second cylinder 6.

[0077] The pistons 122, 123 are slidable in the up-down direction in the figure within the piston chambers 126, 127. More specifically, they are slidable between a lower limit position and an upper limit position. The lower limit position is a position where the pistons 122, 123 abut against the bottoms of the piston chambers 126, 127 as shown in Figure 4, and the upper limit position is a position where the pistons 122, 123 have slid a distance D1 toward the second cylinder 6, i.e., a position where the piston 123 abuts against the first restricting portion 68.

[0078] In addition, the first cylinder housing 121 has a female thread portion 128 at the end of the inner surface of the opening 124 on the second cylinder 6 side, and the second cylinder 6 is connected to the first cylinder 12 by being screwed into the female thread portion 128.

[0079] The second cylinder 6 has the same configuration as the fluid control valve 1, and a male threaded portion 651 provided on the outer peripheral surface of a bottom portion 65 is threadedly engaged with a female threaded portion 128, so that the bottom portion 65 closes the piston chamber 127 and forms a part of the first cylinder 12. Furthermore, because the second cylinder 6 is threadedly engaged with the first cylinder 12, its axial position relative to the first cylinder 12 can be adjusted continuously by adjusting the threading depth. This means that the distance D1 between the piston 123 and the first restricting portion 68 when the piston 123 is at its lowest position (i.e., the stroke between the lowest and highest positions of the piston 123) can be adjusted.

[0080] In the fluid control valve 100, the diameters of the pistons 122, 123 are set to be the same as the diameter of the second piston 62, so there is no space to provide the first photoelectric sensor 21 that was provided in the fluid control valve 1. Therefore, only the second photoelectric sensor 22 is provided, and by detecting the position of the second piston 62, it is detected whether the diaphragm member 34 is at the first opening degree, the third opening degree, or the second opening degree.

[0081] The drive shaft 7 inserted into the cylinder portion 11 differs from that of the fluid control valve 1 in the following points.

[0082] A supply passage 71 provided in the drive shaft 7 is branched into a first branch passage 711A communicating with the lower chamber 1262 of the piston chamber 126, a first branch passage 711B communicating with the lower chamber 1272 of the piston chamber 127, and a second branch passage 712 communicating with the lower chamber 672 of the second piston chamber 67. Thus, when compressed air is supplied to the supply passage 71, the compressed air flows into the lower chamber 1262 of the piston chamber 126 via the first branch passage 711A, flows into the lower chamber 1272 of the piston chamber 127 via the first branch passage 711B, and flows into the lower chamber 672 of the second piston chamber 67 via the second branch passage 712. This causes the pistons 122, 123 and the second piston 62 to slide.

[0083] The drive shaft 7 is provided with a first engagement portion 72A protruding in the radial direction of the drive shaft 7 on a portion of its outer circumferential surface facing the upper chamber 1261 of the piston chamber 126, and a first engagement portion 72B protruding in the radial direction of the drive shaft 7 on a portion facing the upper chamber 1271 of the piston chamber 127. When the pistons 122, 123 slide from the lower limit position to the upper limit position, the pistons 122, 123 come into contact with the first engagement portions 72A, 72B, thereby pushing the drive shaft 7 upward in the separation direction against the biasing forces of the first compression coil spring 64 and the second compression coil spring 42 in the contact direction. Note that the drive shaft 7 is provided with a second engagement portion 73, similar to the fluid control valve 1.

[0084] In the fluid control valve 100 configured as described above, similarly to the fluid control valve 1, the opening degree of the diaphragm member 34 can be controlled in two stages, the second opening degree and the third opening degree, depending on whether compressed air is supplied at the first pressure (0.4 MPa) or the second pressure (0.6 MPa). Furthermore, because compressed air at the first pressure or the second pressure is supplied to the first cylinder 12 and the second cylinder 6 through the supply path 71 provided in the drive shaft 7, the piping 10 for supplying compressed air need only be connected to this supply path 71. This makes it possible to reduce the piping space.

[0085] The above-described embodiment is merely an example and does not limit the present invention in any way. Naturally, the present invention can be improved and modified in various ways without departing from the spirit and scope of the present invention.

[0086] For example, in the fluid control valve 1 (100) according to this embodiment, the first pressure is described as 0.4 MPa and the second pressure is described as 0.6 MPa, but these pressure values ​​are not limited to these. The first pressure is adjusted to a pressure that can operate the diaphragm member 34 to the third opening degree, taking into consideration the pressure-receiving areas of the first piston 52 (122, 123) and the second piston 62 and the elastic forces of the first compression coil spring 64 and the second compression coil spring 42. The second pressure is adjusted to a pressure that can operate the diaphragm member 34 to the second opening degree, taking into consideration the pressure-receiving area of ​​the second piston 62 and the elastic forces of the first compression coil spring 64 and the second compression coil spring 42.

[0087] Furthermore, the fluid control valve 1 (100) according to this embodiment has been described as a configuration in which the drive shaft 7 and the diaphragm member 34 are not connected (separate type), but it may also be an integrated valve device in which the drive shaft 7 and the diaphragm member 36 are connected, as shown in Figure 5. Specifically, this is as follows.

[0088] As shown in FIG. 5 , a valve element 37 (an example of a valve element) for moving into and out of contact with the valve seat 33 is coupled to a tip end 75 of the drive shaft 7 on the valve section 3 side. The diaphragm member 36 is formed to have a spherical band shape that bulges toward the drive shaft 7 in its natural state. The diaphragm member 36 is sandwiched and fixed at its center between the tip end 75 and the valve element 37, with its center positioned on an extension of the axial center of the drive shaft 7. Instead of being sandwiched and fixed, the diaphragm member 36 may be joined by, for example, laser welding. The outer periphery of the diaphragm member 36 is sandwiched and fixed from above and below within the valve section 3. By being fixed in this manner, the diaphragm member 36 divides the valve chamber 311 into the valve chamber 311 and an upper portion thereof, and repeatedly elastically deforms as the valve element 37 moves in the direction of contact and separation.

[0089] With the above configuration, similar to the fluid control valve 1, the opening degree of the valve body 37 can be controlled in two stages, the second opening degree and the third opening degree, depending on whether the compressed air is supplied at the first pressure (0.4 MPa) or the second pressure (0.6 MPa).

[0090] REFERENCE SIGNS LIST 1 fluid control valve 2 cylinder portion 5 first cylinder 6 second cylinder 7 drive shaft 33 valve seat 34 diaphragm member (an example of a valve body) 42 second compression coil spring (an example of a biasing member) 52 first piston 62 second piston 64 first compression coil spring (an example of a biasing member) 71 supply path

Claims

1. A fluid control valve comprising: a valve seat; a valve element that moves toward and away from the valve seat between a first opening at which the valve element is in contact with the valve seat and a second opening at which the valve element is most distant from the valve seat; a drive shaft for performing the movement of the valve element toward and away from the valve seat; a cylinder portion through which the drive shaft is inserted along the direction of the movement of the valve element toward and away from the valve seat; a piston that is loaded into the cylinder portion and receives fluid pressure from an operating fluid supplied to the cylinder portion, thereby moving the drive shaft in the separating direction in which the valve element moves away from the valve seat; and a biasing member that applies a biasing force to the piston in the direction of contact that is opposite to the separating direction, wherein the cylinder portion comprises a first cylinder and a second cylinder that are stacked along the axial direction of the drive shaft; the drive shaft comprises a supply path that supplies the operating fluid to each of the first cylinder and the second cylinder at a first pressure or a second pressure higher than the first pressure; and the piston is a first piston that is loaded in the first cylinder and that, when the operating fluid is supplied to the first cylinder at the first pressure, moves the drive shaft in the separating direction from the first opening until the valve element moves from the first opening to a third opening between the first opening and the second opening; and a second piston that is loaded in the second cylinder and, when the operating fluid is supplied to the second cylinder at the first pressure, moves the drive shaft in the separating direction together with the first piston until the valve element moves from the first opening to the third opening, and, when the operating fluid is supplied to the second cylinder at the second pressure, moves the drive shaft in the separating direction alone until the valve element moves from the third opening to the second opening.

2. A fluid control valve as claimed in claim 1, wherein the first cylinder is provided with a first restricting part that abuts against the first piston from the side in the separating direction and restricts the valve element to the third opening degree, and the second cylinder is provided with a second restricting part that abuts against the second piston from the side in the separating direction and restricts the valve element to the second opening degree.

3. A fluid control valve as claimed in claim 2, characterized in that: the first restricting portion is formed at the end of the second cylinder on the side of the first cylinder; the second cylinder is screwed to the first cylinder so that its position in the axial direction is adjustable, and the position of the first restricting portion in the axial direction can be adjusted by adjusting the position of the second cylinder; and the second restricting portion is screwed to the second cylinder on the side of the second cylinder opposite to the side of the first cylinder so that its position in the axial direction is adjustable.

4. A fluid control valve according to any one of claims 1 to 3, characterized in that the pressure-receiving area of ​​the first piston is larger than the pressure-receiving area of ​​the second piston.

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