Fluid valve

Abstract

A fluid valve 1 comprises: a diaphragm 301 disposed so as to be capable of abutting on and separating from a valve seat 105; a first piston 310 disposed so as to be capable of moving toward and separating from the valve seat 105; a second piston 320 to which the diaphragm 301 is attached, the second piston 320 being disposed inside the first piston 310 so as to be capable of moving toward and separating from the valve seat 105; and a drive mechanism 50 for controlling opening / closing of the valve seat 105 by moving the first piston 310 and the second piston 320 according to actuating air. The drive mechanism 50 has a first spring 51 that biases the first piston 310 in a direction toward the valve seat 105, and a second spring 52 that is disposed inside the first spring 51 and biases the second piston 320 in a direction toward the valve seat 105. The travel distance of the first piston 310 is longer than the travel distance of the second piston 320.

Description

Fluid Valve

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

[0002] In an operating valve for controlling a fluid, particles may be generated due to peeling of the material structure caused by the impact when the valve part is seated on the valve seat.

[0003] Patent Document 1 discloses an operating valve that suppresses the generation of such particles. The operating valve in Patent Document 1 has a first piston portion that descends due to the spring load of a first spring, and a second piston portion that houses the first piston portion and descends due to the spring load of a second spring. The spring load of the second spring is greater than the spring load of the first spring.

[0004] When the supply pressure of the working air decreases, the first piston part descends first, followed by the second piston part. As the first piston part descends, the valve part receives a weak biasing force from the first spring and seats on the valve seat. The second piston part descends later, pressing the first piston part, which then receives the biasing force of the second spring via the first piston part, sealing the valve seat. In this way, Patent Document 1 suppresses the impact when the valve part seats on the valve seat and reduces the generation of particles.

[0005] JP 2012-107695 A

[0006] In Patent Document 1, the first spring that lowers the first piston portion and the second spring that lowers the second piston portion are arranged in series along the direction in which the first piston portion and the second piston portion move, which poses a problem that the operating valve becomes large in size along the direction in which the first piston portion and the second piston portion move.

[0007] In one embodiment, the fluid valve includes a flow path block having a valve chamber with a valve seat formed between an inlet and an outlet for a fluid, a cylinder portion attached to the flow path block, a diaphragm arranged in the valve chamber so as to be able to abut against and separate from the valve seat, a first piston arranged in the cylinder portion so as to be able to approach and separate from the valve seat, a second piston to which the diaphragm is attached and at least a portion of which is arranged inside the first piston so as to be able to approach and separate from the valve seat, and a drive mechanism that moves the first piston and the second piston in response to operating air to control opening and closing of the valve seat. The drive mechanism includes a first spring that urges the first piston in a direction approaching the valve seat, and a second spring that is arranged inside the first spring and urges the second piston in a direction approaching the valve seat. The movement distance of the first piston is longer than the movement distance of the second piston. When the operating air is exhausted, the first piston and the second piston move in a direction approaching the valve seat due to the biasing force of the first spring and the second spring, and when the diaphragm abuts against the valve seat, the movement of the second piston stops, and only the first piston moves in a direction approaching the valve seat due to the biasing force of the first spring and abuts against the second piston, pressing the diaphragm against the valve seat.

[0008] According to the present invention, the second spring that biases the second piston is arranged inside the first spring that biases the first piston, thereby preventing the fluid valve from becoming larger in size in the direction of movement of the first piston and the second piston.

[0009] 1 is a cross-sectional view of the fluid valve of the embodiment when it is in an open state; FIG. 2 is a cross-sectional view of the fluid valve during transition from a closed state to an open state; FIG. 3 is a cross-sectional view of the fluid valve 1 in an open state; FIG. 4 is a cross-sectional view of the fluid valve during transition from an open state to a closed state; FIG. 5 is a cross-sectional view of the fluid valve of the first modified example when it is in a closed state; FIG. 6 is a cross-sectional view of the fluid valve of the first modified example when it is in an open state; and FIG. 7 is a cross-sectional view of the fluid valve of the second modified example when it is in a closed state.

[0010] A fluid valve according to an embodiment of the present invention will now be described in detail with reference to the drawings. The fluid valve according to the present embodiment can be installed in a device that dispenses a liquid (fluid) such as a resist (chemical) onto a wafer in a semiconductor manufacturing process, for example.

[0011] 1 is a cross-sectional view of a fluid valve 1, showing the fluid valve 1 in a closed state. The closed state is a state in which the flow of fluid through the fluid valve 1 is restricted.

[0012] The fluid valve 1 includes a flow path block 10, a cylinder section 20, a valve mechanism 30, and a drive mechanism 50. The flow path block 10, the cylinder section 20, and the valve mechanism 30 are arranged along the axis X shown in the figure. Note that in the direction along the axis X of the fluid valve 1, the side on which the flow path block 10 is provided is sometimes referred to as the lower side, and the side on which the cylinder section 20 is provided is sometimes referred to as the upper side.

[0013] <Flow Channel Block 10> The flow channel block 10 is formed of, for example, a resin material or a metal material, and is disposed on a support plate 100. The flow channel block 10 has an inlet 101, an outlet 102, a flow channel 103, a valve chamber 104, and a valve seat 105 formed therein. The inlet 101 and the outlet 102 are openings formed in the flow channel block 10. Fittings 106 and 107, such as union nuts, are attached to the inlet 101 and the outlet 102. The inlet 101 is connected via the fitting 106 to a pipe connected to a pump or the like that sucks up liquid from a tank in which the liquid is stored. The outlet 102 is connected via the fitting 107 to a pipe connected to a nozzle that drips liquid onto a wafer.

[0014] The flow path 103 connects the inlet 101 and the outlet 102 within the flow path block 10. A fluid such as a liquid that flows in from the inlet 101 passes through the flow path 103 and flows out of the flow path block 10 from the outlet 102. The valve chamber 104 is an opening provided in the flow path 103 and formed at the upper end of the flow path block 10. A valve seat 105 having a central axis coincident with the axis X is formed in the valve chamber 104.

[0015] <Cylinder section 20> The cylinder section 20 is attached above the flow path block 10. The cylinder section 20 is formed from, for example, a resin material or a metal material. The cylinder section 20 is formed in a cylindrical shape with the axis line X as the central axis. The cylinder section 20 has a main body section 201 and a cover section 202 that is fixed to the upper part of the main body section 201 by a fastening screw or the like.

[0016] The main body 201 has a cylindrical shape with the axis X as its central axis and a piston accommodating hole 203 that is open at the top and bottom. An air port 204 is formed on the outer surface of the main body 201. The air port 204 is an opening that allows working air, which is a fluid such as compressed air, to flow into the piston accommodating hole 203 or to discharge the working air from the piston accommodating hole 203.

[0017] An accommodating protrusion 210 extending upward is formed on the bottom surface 210a of the main body 201. The accommodating protrusion 210 is a cylindrical wall surface formed with the axis X as its central axis, and the inner diameter of the accommodating protrusion 210 is smaller than the inner diameter of the main body 201. Furthermore, the length of the accommodating protrusion 210 in the up-down direction is shorter than the length of the main body 201 in the up-down direction.

[0018] The piston accommodating hole 203 is divided into a first accommodating portion 203a and a second accommodating portion 203b by the accommodating protrusion 210. The second accommodating portion 203b is a region of the piston accommodating hole 203 that is surrounded by the inner circumferential wall surface of the accommodating protrusion 210. The first accommodating portion 203a is a region of the piston accommodating hole 203 other than the second accommodating portion 203b. A part of a first piston 310 of the valve mechanism 30 (described later) is accommodated in the first accommodating portion 203a. A second piston 320 and another part of the first piston 310 of the valve mechanism 30 (described later) are accommodated in the second accommodating portion 203b.

[0019] The cover portion 202 is fixed to the upper part of the main body portion 201 via a sealing member 202a such as an O-ring, thereby closing the upper opening of the piston accommodating hole 203. The cover portion 202 is formed with a downward protrusion 220 that extends downward along the inner circumferential wall surface of the main body portion 201. The downward protrusion 220 is a cylindrical wall surface formed with the axis X as its central axis, and the outer diameter of the downward protrusion 220 is smaller than the inner diameter of the main body portion 201.

[0020] A holding portion 221 that holds a drive mechanism 50 (described later) is provided within the space surrounded by the downward protruding portion 220. In other words, the holding portion 221 is provided within the cylinder portion 20 at a position that is farther away from the valve seat 105 than a valve mechanism 30 (first piston 310 and second piston 320) (described later) is. The holding portion 221 has a shaft portion 222 whose central axis is the axis X, and a flange portion 223 provided on an upper portion of the shaft portion 222. An upper portion of the holding portion 221 is attached to the underside of the cover portion 202.

[0021] <Valve Mechanism 30> The valve mechanism 30 has a diaphragm 301, a first piston 310, and a second piston 320. The diaphragm 301 is formed of, for example, a resin material. The valve mechanism 30 moves back and forth along the axis X in a closing direction (downward) in which the diaphragm 301 closes the valve seat 105, and in a separating direction (upward) in which the diaphragm 301 moves away from the valve seat 105, as described below.

[0022] <Diaphragm 301> The diaphragm 301 has a seal portion 303, a movable membrane portion 304, and an outer peripheral portion 305, and is disposed within the valve chamber 104. The seal portion 303 comes into contact with or separates from the valve seat 105 as the valve mechanism 30 moves back and forth along the axis X, as will be described later. In other words, the diaphragm 301 is disposed within the valve chamber 104 so as to be able to come into contact with and separate from the valve seat 105.

[0023] The movable membrane portion 304 is a thin portion disposed on the outer periphery of the seal portion 303. The outer periphery portion 305 is disposed along the outer periphery of the movable membrane portion 304. The outer periphery portion 305 is sandwiched between the mounting surface 110 formed inside the flow path block 10 and the washer 400.

[0024] <First Piston 310> The first piston 310 is accommodated (disposed) in the piston accommodation hole 203 of the cylinder portion 20 so as to be able to reciprocate (advance and retreat) in the up and down direction along the axis X, i.e., so as to be able to approach and move away from the valve seat 105. The first piston 310 is formed from, for example, a resin material or a metal material. The first piston 310 is formed by a large diameter portion 311 and a small diameter portion 312 that have different diameters centered on the axis X.

[0025] The large diameter portion 311 has an outer diameter approximately equal to the inner diameter of the main body portion 201 and is formed in a cylindrical shape that is open at the top. The small diameter portion 312 is formed below the large diameter portion 311. The small diameter portion 312 has an outer diameter approximately equal to the inner diameter of the accommodating protrusion 210 and is formed in a cylindrical shape that is open at the top and bottom. In other words, the small diameter portion 312 is a cylindrical portion that extends downward from the bottom surface 311a of the large diameter portion 311. Therefore, in the first piston 310 accommodated in the piston accommodating hole 203, the large diameter portion 311 is accommodated in the first accommodating portion 203a and the small diameter portion 312 is accommodated in the second accommodating portion 203b. A groove 313 is formed along the outer periphery on the outer peripheral side surface of the large diameter portion 311, and an elastic member 314 such as a packing is accommodated in the groove 313. A groove 315 is formed along the outer periphery of the outer periphery of the small diameter portion 312, and an elastic member 316 such as a packing is housed in the groove 315.

[0026] Both the large diameter portion 311 and the small diameter portion 312 have a cylindrical shape with the axis X as the central axis. The inner diameter of the large diameter portion 311 is larger than the inner diameter of the small diameter portion 312. As described above, the large diameter portion 311 is open at the top, and the small diameter portion 312 is open at the top and bottom. Therefore, the interior surrounded by the side wall surface of the small diameter portion 312 is an insertion hole 317 that passes through the first piston 310 in the vertical direction and into which the second piston 320, described below, is inserted. In other words, the inner diameter of the large diameter portion 311 of the first piston 310 is larger than the diameter of the insertion hole 317.

[0027] <Second Piston 320> At least a portion of the second piston 320 is disposed inside the first piston 310 so as to be able to reciprocate (advance and retreat) in the up and down direction along the axis X, i.e., so as to be able to approach and move away from the valve seat 105. The second piston 320 is formed, for example, from a resin material or a metal material, and has a piston shaft portion 321 which is a first portion, a piston head portion 322 which is a second portion, and an attachment portion 323 which is a third portion.

[0028] The piston shaft 321 is a rod-shaped member extending in the vertical direction about the axis X, and is inserted into an insertion hole 317 formed in the first piston 310. In other words, the diameter of the piston shaft 321 is smaller than the diameter of the insertion hole 317.

[0029] The piston head 322 has a male thread portion 322a and a flange 322b extending in the vertical direction about the axis X. The piston head 322 is provided on the upper part of the piston shaft portion 321. Specifically, the male thread portion 322a of the piston head 322 is threadedly coupled to a female thread formed on the upper end of the piston shaft portion 321. In other words, the piston head 322 is attached at a position farther away from the valve seat 105 than the piston shaft portion 321.

[0030] The flange 322b has a diameter larger than the insertion hole 317 and smaller than the inner diameter of the large diameter portion 311. When the second piston 320 is disposed inside the first piston 310, the flange 322b is located above the bottom surface 311a of the large diameter portion 311 of the first piston 310. In other words, the piston head 322 protrudes in a direction away from the valve seat 105 beyond the bottom surface 311a of the first piston 310.

[0031] The mounting portion 323 is a rod-shaped member provided at the lower end of the piston shaft portion 321 and extending in the vertical direction with the axis X as its central axis. The diameter of the mounting portion 323 is larger than the diameter of the insertion hole 317. In other words, because the diameter of the mounting portion 323 is larger than the diameter of the piston shaft portion 321, a stepped surface 324 is formed at the upper end of the mounting portion 323. When the second piston 320 is disposed inside the first piston 310, the stepped surface 324 is located below the lower end surface 312 a of the small diameter portion 312 of the first piston 310.

[0032] The vertical distance between the stepped surface 324 and the lower surface of the flange 322b is longer than the vertical distance of the small-diameter portion 312 (insertion hole 317) of the first piston 310. Therefore, depending on the operating state (open state or closed state) of the fluid valve 1, a gap is generated between the lower surface of the flange 322b and the bottom surface 311a of the large-diameter portion 311, or between the stepped surface 324 and the lower end surface 312a of the small-diameter portion 312. In other words, when the state of the fluid valve 1 transitions between the open state and the closed state, as described below, the vertical movement distance of the first piston 310 is longer than the vertical movement distance of the second piston 320 by the amount of this gap. More specifically, the first piston 310 is movable relative to the second piston 320 between the flange 322b and the stepped surface 324.

[0033] The diaphragm 301 is attached to the lower end of the attachment portion 323. Specifically, a female thread extending in the vertical direction is formed at the lower end of the attachment portion 323. This female thread is threadedly coupled to a male thread formed on a protrusion 306 formed on the upper side of the seal portion 303 of the diaphragm 301. In this way, the diaphragm 301 is attached to the second piston 320.

[0034] <Drive mechanism 50> The drive mechanism 50 includes a first spring 51 and a second spring 52. The first spring 51 and the second spring 52 are housed in the piston housing hole 203. The first spring 51 is a coil spring having an inner diameter larger than the diameter of the shaft portion 222 of the holder 221 attached to the cover portion 202 and the diameter of the flange 322b of the piston head portion 322 of the second piston 320. Therefore, the upper end (one side) of the first spring 51 abuts against the flange portion 223 of the holder 221, and the lower end (the other side) abuts against the bottom surface 311a of the large diameter portion 311 of the first piston 310. As a result, the first spring 51 biases the first piston 310 downward, i.e., in a direction approaching the valve seat 105.

[0035] The second spring 52 is a coil spring having an outer diameter smaller than the inner diameter of the first spring 51. More specifically, the inner diameter of the second spring 52 is larger than the diameter of the shaft portion 222 of the retaining portion 221 attached to the cover portion 202, and the outer diameter of the second spring 52 is smaller than the diameter of the flange 322b of the piston head portion 322 of the second piston 320. Therefore, the upper end portion (one side) of the second spring 52 abuts against the flange portion 223 of the retaining portion 221, and the lower end portion (the other side) abuts against the piston head portion 322 of the second piston 320. As a result, the second spring 52 biases the second piston 320 downward, i.e., in a direction approaching the valve seat 105.

[0036] As described above, the inner diameter of the first spring 51 is larger than the outer diameter of the second spring 52, and the inner diameter of the second spring 52 is larger than the diameter of the shaft portion 222 of the retaining portion 221. For this reason, it can be said that the second spring 52 is disposed inside the first spring 51. Furthermore, it can be said that the shaft portion 222 of the retaining portion 221 is inserted inside the first spring 51 and the second spring 52. Note that the inside of the first spring 51 refers to the side closer to the axis X than the first spring 51, which is a coil spring, and the inside of the second spring 52 refers to the side closer to the axis X than the second spring 52, which is a coil spring.

[0037] As will be described later, when operating air such as compressed air is exhausted from the piston accommodating hole 203, the first piston 310 and the second piston 320 move downward due to the biasing forces of the first spring 51 and the second spring 52. In other words, the diaphragm 301 abuts against the valve seat 105, thereby closing the valve seat 105.

[0038] At this time, the first spring 51 and the second spring 52 ensure the force (closing force) required for the diaphragm 301 to close the valve seat 105. In other words, the biasing forces of the first spring 51 and the second spring 52 are determined so that the sum of their respective biasing forces corresponds to the closing force. In this case, the biasing forces of the first spring 51 and the second spring 52 may be the same, or the biasing force of the first spring 51 may be greater or smaller than the biasing force of the second spring 52. However, the biasing force of the second spring 52 is slightly stronger than the force exerted upward on the seal portion 303 of the diaphragm 301 by the pressure of the fluid in the valve chamber 104 when the diaphragm 301 abuts against the valve seat 105.

[0039] Furthermore, when working air is supplied to the piston accommodating hole 203, the first piston 310 and the second piston 320 move upward against the biasing force of the first spring 51 and the second spring 52. That is, the diaphragm 301 moves away from the valve seat 105, thereby opening the valve seat 105. In other words, the drive mechanism 50 having the first spring 51 and the second spring 52 moves the first piston 310 and the second piston 320 in response to working air supplied to or discharged from the air port 204, thereby controlling the opening and closing of the valve seat 105.

[0040] 1 , when the fluid valve 1 is in the closed state, operating air such as compressed air is not supplied from the air port 204 to the piston housing hole 203. Therefore, the first piston 310 and the second piston 320 are moved in the closing direction along the axis X by the biasing force of the drive mechanism 50. The step surface 324 of the second piston 320 and the lower end surface 312a of the small diameter portion 312 of the first piston 310 come into contact with each other, and a gap S1 is generated between the lower surface of the flange 322b of the second piston 320 and the bottom surface 311a of the large diameter portion 311 of the first piston 310.

[0041] As the first piston 310 and the second piston 320 move downward, the diaphragm 301 attached to the second piston 320 also moves downward. As a result, the seal portion 303 of the diaphragm 301 abuts against the valve seat 105.

[0042] <Transition from Closed State to Open State> Figure 2 is a cross-sectional view of the fluid valve 1 transitioning from a closed state to an open state. Figure 3 is a cross-sectional view of the fluid valve 1 transitioning to an open state. Below, we will explain how the fluid valve 1 transitions from the closed state shown in Figure 1 to the open state shown in Figure 3 via the state shown in Figure 2.

[0043] When the fluid valve 1 is in a closed state, supply of operating air such as compressed air to the piston housing hole 203 begins via the air port 204. Due to the pressure in the piston housing hole 203 increased by the supply of operating air, the first piston 310 begins to move in the separating direction (upward) along the axis X against the downward biasing force of the first spring 51.

[0044] 2, as a result of the first piston 310 moving upward, the bottom surface 311a of the large diameter portion 311 of the first piston 310 comes into contact with the lower surface of the flange 322b of the second piston 320. In other words, a gap S2 is generated between the step surface 324 of the second piston 320 and the lower end surface 312a of the small diameter portion 312 of the first piston 310.

[0045] In this state, if operating air is further supplied to the piston receiving hole 203, the first piston 310 continues to move in the separating direction, and an upward force is applied from the first piston 310 to the second piston 320 via the bottom surface 311a. This force, combined with an increase in pressure within the piston receiving hole 203, causes the second piston 320 to move in the separating direction along the axis X against the biasing force of the second spring 52. That is, when the first piston 310 comes into contact with the flange 322b, both the first piston 310 and the second piston 320 move in the separating direction against the biasing forces of the first spring 51 and the second spring 52. The diaphragm 301 moves upward as the second piston 320 moves upward. That is, the seal portion 303 of the diaphragm 301 begins to move away from the valve seat 105.

[0046] As the first piston 310 continues to move in the separating direction, the upper end 311b of the large diameter portion 311 abuts against the lower end 220a of the downward protrusion 220 of the cover portion 202. In this state, the first piston 310 and the second piston 320 stop moving in the separating direction. As a result, the seal portion 303 of the diaphragm 301, which moved in the separating direction together with the second piston 320, is held in a position separated from the valve seat 105, and the valve seat 105 is in an open state. In other words, the fluid valve 1 transitions to the open state shown in FIG. 3 .

[0047] <Transition from Open State to Closed State> Figure 4 is a cross-sectional view of the fluid valve 1 during transition from the open state to the closed state. Below, we will explain the case where the fluid valve 1 in the open state shown in Figure 3 transitions to the closed state shown in Figure 1 via the state shown in Figure 4.

[0048] Working air, such as compressed air, is discharged from the airport 204 through the piston housing bore 203. In this case, the working air is exhausted at a small flow rate (meter-out control) by, for example, a speed controller. When the working air is discharged and the pressure in the piston housing bore 203 decreases, the first piston 310 and the second piston 320 start to move in the closing direction (downward) along the axis X due to the biasing forces of the first spring 51 and the second spring 52. In addition, the seal portion 303 of the diaphragm 301 attached to the second piston 320 also starts to move in the closing direction.

[0049] In the open state, as described above, the bottom surface 311a of the large diameter portion 311 of the first piston 310 abuts against the lower surface of the flange 322b of the second piston 320, and a gap S2 is generated between the stepped surface 324 of the second piston 320 and the lower end surface 312a of the small diameter portion 312 of the first piston 310. The first piston 310 and the second piston 320 move in the closing direction while maintaining the above-described positional relationship.

[0050] 4 shows the state when the first piston 310, the second piston 320, and the seal portion 303 of the diaphragm 301 move in the closing direction as described above, and the seal portion 303 abuts against the valve seat 105. When the seal portion 303 abuts against the valve seat 105, the downward movement of the seal portion 303 stops. At the same time, the downward movement of the second piston 320 to which the diaphragm 301 is attached also stops.

[0051] At this time, the positional relationship between first piston 310 and second piston 320 is the same as when they started to move in the closing direction. That is, bottom surface 311a of large diameter portion 311 abuts on the lower surface of flange 322b, and gap S2 is generated between step surface 324 and lower end surface 312a of small diameter portion 312. Therefore, diaphragm 301 abuts against valve seat 105 by the biasing force of second spring 52 via second piston 320.

[0052] As described above, the biasing force of the first spring 51 and the biasing force of the second spring 52 are determined so that the sum of their respective biasing forces corresponds to the closing force. In other words, the biasing force of the second spring 52 alone is less than the closing force. Therefore, the diaphragm 301 contacts the valve seat 105 with a force less than the closing force, and the impact is weaker than when the diaphragm 301 is subjected to the closing force.

[0053] Thereafter, as the working air is further exhausted, only the first piston 310 moves in the closing direction. Specifically, after the diaphragm 301 shown in Fig. 4 abuts against the valve seat 105, the first piston 310 moves downward by the gap S2, i.e., in a direction approaching the valve seat 105. Then, as shown in Fig. 1, when the lower end surface 312a of the small diameter portion 312 abuts against the stepped surface 324, the downward movement of the first piston 310 stops.

[0054] At this time, the biasing force of the first spring 51 biasing the first piston 310 acts on the diaphragm 301 via the mounting portion 323 on which the stepped surface 324 is formed. That is, the biasing force of the first spring 51 acts on the diaphragm 301 in addition to the biasing force of the second spring 52 via the second piston 320. As described above, the biasing forces of the first spring 51 and the second spring 52 are determined so that the sum of their respective biasing forces corresponds to the closing force. Therefore, the diaphragm 301 is pressed against the valve seat 105 by the closing force, and the fluid valve 1 is in the closed state shown in FIG. 1 .

[0055] As described above, the diaphragm 301 initially contacts the valve seat 105 with a force smaller than the closing force, thereby reducing the impact of closing the valve seat 105. This reduces the generation of particles and the occurrence of the water hammer phenomenon caused by a sudden change in pressure in the flow path 103. As a result, splashing of liquid from the nozzle connected to the outlet 102 is suppressed. The diaphragm 301 is then pressed against the valve seat 105 by the first piston 310. As a result, the diaphragm 301 closes the valve seat 105 with the required closing force, thereby preventing fluid from leaking from the closed fluid valve 1.

[0056] According to the above-described embodiment, at least one of the following advantageous effects can be obtained.

[0057] (1) The fluid valve 1 includes a diaphragm 301, a first piston 310, a second piston 320, and a drive mechanism 50. The diaphragm 301 is disposed in the valve chamber 104 so as to be able to abut against and separate from the valve seat 105. The first piston 310 is disposed in the cylinder portion 20 so as to be able to approach and separate from the valve seat 105. The second piston 320 is attached to the diaphragm 301, and at least a portion of the second piston 320 is disposed inside the first piston 310 so as to be able to approach and separate from the valve seat 105. The drive mechanism 50 moves the first piston 310 and the second piston 320 in response to working air to control the opening and closing of the valve seat 105. The drive mechanism 50 includes a first spring 51 that urges the first piston 310 in a direction approaching the valve seat 105, and a second spring 52 that is disposed inside the first spring 51 and urges the second piston 320 in a direction approaching the valve seat 105. The travel distance of the first piston 310 is longer than the travel distance of the second piston 320. When the operating air is exhausted, the biasing forces of the first spring 51 and the second spring 52 cause the first piston 310 and the second piston 320 to move in a direction approaching the valve seat 105. When the diaphragm 301 abuts against the valve seat 105, the movement of the second piston 320 stops, and only the first piston 310 moves in a direction approaching the valve seat 105 due to the biasing force of the first spring 51 until it abuts against the second piston 320 and presses the diaphragm 301 against the valve seat 105.

[0058] As a result, when the diaphragm 301 contacts the valve seat 105, only the biasing force of the second spring 52 acts, thereby reducing the impact caused by the valve mechanism 30 when the valve seat 105 is closed. Because the impact when the valve seat 105 is closed is reduced, the generation of particles and the occurrence of the water hammer phenomenon caused by a sudden change in pressure in the flow path 103 are suppressed. This also prevents the liquid from splashing from the nozzle connected to the outlet 102. Since the liquid is prevented from splashing from the nozzle, it is possible to prevent the liquid from adhering to an unintended position on the object onto which the liquid is to be dropped (e.g., a wafer, etc.), resulting in a defective object. Furthermore, since the liquid splashing is suppressed, an amount of liquid different from the desired amount is prevented from being dropped onto the object, contributing to maintaining the quality of the object.

[0059] Furthermore, because the second spring 52 is disposed inside the first spring 51, unlike when the first spring 51 and the second spring 52 are disposed in series along the movement direction of the valve mechanism 30 (i.e., the direction along the axis X), an increase in size of the fluid valve 1 in the direction along the axis X can be suppressed. That is, this contributes to a reduction in the size of the fluid valve 1, which reduces the impact when the valve seat 105 is closed. Furthermore, an existing fluid valve having a structure in which a single piston is biased by a single spring can be replaced with the drive mechanism 50 of this embodiment in which the valve mechanism 30 and the second spring 52 are disposed inside the first spring 51, thereby improving the fluid valve 1 to one that can reduce the impact when the valve seat 105 is closed.

[0060] Furthermore, unlike configurations in which an elastic member such as a rubber cushion is used to absorb the impact when the valve seat 105 is closed, the fluid valve 1 of this embodiment does not lose the force with which the first piston 310 and the second piston 320 press against the diaphragm 301 after they are seated, thereby preventing a weakening of the force closing the valve seat 105. Therefore, when the fluid valve 1 is in the closed state, it is possible to prevent fluid from leaking from the valve seat 105.

[0061] Furthermore, when an elastic member is used to absorb shock, the elastic member must be thick. In contrast, in the fluid valve 1 of this embodiment, the urging force of the second spring 52 causes the diaphragm 301 to abut against the valve seat 105, thereby reducing shock. This eliminates the need to secure space to accommodate the elastic member, thereby preventing the fluid valve 1 from becoming larger. Furthermore, when an elastic member is used, there is a risk that the shock absorption capacity will change due to deterioration over time. In contrast, in this embodiment, changes in the shock absorption capacity due to deterioration over time are suppressed.

[0062] (2) The second piston 320 has a piston shaft 321 as a first portion, a piston head 322 as a second portion, and an attachment portion 323 as a third portion. The piston shaft 321 is inserted into an insertion hole 317 formed in the first piston 310. The piston head 322 is provided with a flange 322b having a diameter larger than the diameter of the insertion hole 317 and is attached to the piston shaft 321 at a position spaced apart from the diaphragm 301. The diaphragm 301 is attached to the attachment portion 323. The inner diameter of the first piston 310 is larger than the diameter of the insertion hole 317 and the diameter of the flange 322b, and the piston head 322 protrudes beyond the bottom surface 311a of the first piston 310 in a direction away from the valve seat. One side (upper end) of the first spring 51 abuts against the retaining portion 221, and the other side (lower end) abuts against the bottom surface 311a. One side (upper end) of the second spring 52 abuts against the retaining portion 221, and the other side (lower end) abuts against the piston head portion 322. This allows the second spring 52, which biases the second piston 320, to be disposed inside the first spring 51, thereby preventing the fluid valve 1 from becoming larger in size in the direction along the axis X.

[0063] (3) The diameter of the attachment portion 323 is larger than the diameter of the piston shaft portion 321, and the first piston 310 moves relative to the second piston 320 between the piston head portion 322 and the attachment portion 323. This makes it possible to differentiate the timing at which the first piston 310 and the second piston 320 press the diaphragm 301 downward, and to bring the diaphragm 301 into contact with the valve seat 105 by the second piston 320 alone, thereby reducing impact.

[0064] (4) Even after the diaphragm 301 abuts against the valve seat 105 and the movement of the second piston 320 stops, the first piston 310 continues to move in a direction approaching the valve seat 105 and abuts against the attachment portion 323. That is, after the second piston 320, biased by the second spring 52, causes the diaphragm 301 to abut against the valve seat 105, the first piston 310, biased by the first spring 51, presses the diaphragm 301 against the valve seat 105. This reduces the impact when the diaphragm 301 abuts against the valve seat 105 and enables the diaphragm 301 to close the valve seat 105 with a closing force, thereby suppressing fluid leakage from the valve seat 105 of the fluid valve 1 in the closed state.

[0065] <First Modification> A fluid valve according to a first modification will now be described. Below, components similar to those of the fluid valve 1 according to the embodiment will be assigned the same reference numerals, and differences will be mainly described. Points not specifically described are the same as those in the embodiment. The fluid valve according to the first modification has a first piston and a second piston that are different in shape from the first piston 310 and the second piston 320 described above.

[0066] 5 is a cross-sectional view of the fluid valve 1 of the first modified example in a closed state, and FIG. 6 is a cross-sectional view of the fluid valve 1 of the first modified example in an open state. The valve mechanism 30 of the fluid valve 1 has a first piston 330 and a second piston 340.

[0067] <First piston 330> The first piston 330 is formed by a large diameter portion 311 similar to that of the embodiment and a small diameter portion 331 different from that of the embodiment. The small diameter portion 331 has a different length extending in the up-down direction from the small diameter portion 312 of the embodiment. Other shapes of the small diameter portion 331 are similar to those of the small diameter portion 312 of the embodiment.

[0068] <Second piston 340> The second piston 340 has a piston shaft 341 which is a fourth part, a piston head 342 which is a fifth part, and a washer 360. The piston shaft 341 and the piston head 342 are integrally formed. The piston shaft 341 is formed in a rod shape extending in the vertical direction centered on the axis X. The piston shaft 341 is inserted into an insertion hole 317 formed in the first piston 330. In other words, the diameter of the piston shaft 341 is smaller than the diameter of the insertion hole 317.

[0069] A piston head 342 is formed at the upper end of the piston shaft 341, i.e., at a position farther away from the diaphragm 301 than the piston shaft 341. A flange 342a is formed on the piston head 342, the diameter of which is larger than the insertion hole 317 and smaller than the inner diameter of the large diameter portion 311. When the second piston 340 is disposed inside the first piston 330, the flange 342a is positioned above the bottom surface 311a of the large diameter portion 311 of the first piston 330. In other words, the flange 342a protrudes beyond the bottom surface 311a in a direction away from the valve seat 105. Therefore, even in this modified example, the upper end (one side) of the first spring 51 abuts against the flange portion 223 of the retaining portion 221, and the lower end (the other side) abuts against the bottom surface 311a of the large diameter portion 311 of the first piston 330. The upper end (one side) of the second spring 52 abuts against the flange 223 of the holding portion 221, and the lower end (the other side) abuts against the flange 342 a of the piston head portion 342 of the second piston 340. The biasing forces of the first spring 51 and the second spring 52 are the same as those in the embodiment.

[0070] The diaphragm 301 is attached to the lower end of the piston shaft 341 via a washer 360 made of, for example, a metal or ceramic material. In this modified example, the lower end of the piston shaft 341 is also formed with a female thread extending in the vertical direction. This female thread is threadedly coupled with a male thread formed on a protrusion 306 formed on the upper side of the seal portion 303 of the diaphragm 301. The outer diameter of the washer 360 is larger than the diameter of the piston shaft 341.

[0071] The vertical length between the lower end surface 341a of the piston shaft 341, i.e., the upper surface 360a of the washer 360, and the lower surface 342b of the flange 342a is longer than the vertical length of the small diameter portion 331 (insertion hole 317) of the first piston 330. Therefore, depending on the operating state (open state or closed state) of the fluid valve 1, a gap is generated between the lower surface 342b of the flange 342a and the bottom surface 311a of the large diameter portion 311, or between the upper surface 360a of the washer 360 and the lower end surface 331a of the small diameter portion 331. In other words, when the state of the fluid valve 1 transitions between the open state and the closed state, as described below, the vertical movement distance of the first piston 330 is longer than the vertical movement distance of the second piston 340 by the amount of this gap. More specifically, first piston 330 moves relative to second piston 340 between piston head 342 and washer 360 .

[0072] 5 , the lower end surface 331a of the small diameter portion 331 of the first piston 330 abuts against the upper surface 360a of the washer 360. That is, a gap S3 is generated between the lower surface 342b of the flange 342a and the bottom surface 311a of the large diameter portion 311. In this state, when the supply of operating air such as compressed air to the piston housing hole 203 via the air port 204 begins, the first piston 330 begins to move in the separating direction (upward) against the downward biasing force of the first spring 51, as in the case of the embodiment.

[0073] As the first piston 330 moves upward, the bottom surface 311a of the large diameter portion 311 of the first piston 330 comes into contact with the lower surface 342b of the flange 342a of the second piston 340. Then, as in the case of the embodiment, the second piston 340 also moves in the separating direction together with the first piston 330. The diaphragm 301 moves upward in conjunction with the upward movement of the second piston 320, and the seal portion 303 begins to separate from the valve seat 105.

[0074] As the first piston 310 continues to move away from the piston 310, the upper end 311b of the large diameter portion 311 comes into contact with the lower end 220a of the downward protrusion 220 of the cover portion 202. In this state, the first piston 310 and the second piston 320 stop moving away from each other. As a result, the fluid valve 1 transitions to the open state shown in FIG. 6.

[0075] In the open state shown in FIG. 6 , the bottom surface 311a of the large diameter portion 311 of the first piston 330 abuts against the lower surface 342b of the flange 342a. That is, a gap S4 is formed between the upper surface 360a of the washer 360 and the lower end surface 331a of the small diameter portion 331. In this state, when operating air such as compressed air is discharged from the air port 204 through the piston housing hole 203, the first piston 330 and the second piston 340 begin to move in the closing direction due to the biasing forces of the first spring 51 and the second spring 52, as in the embodiment. The seal portion 303 of the diaphragm 301 attached to the second piston 340 also begins to move in the closing direction. At this time, the first piston 330 and the second piston 340 move while maintaining the bottom surface 311a of the large diameter portion 311 abutting against the lower surface 342b of the flange 342a.

[0076] When the diaphragm 301 abuts against the valve seat 105, the downward movement of the diaphragm 301 and the second piston 340 stops, as in the case of the embodiment. Then, the first piston 330 continues to move downward by the gap S4. Then, when the lower end surface 331a of the small diameter portion 331 abuts against the upper surface 360a of the washer 360, the diaphragm 301 is pressed against the valve seat 105.

[0077] When the diaphragm 301 abuts against the valve seat 105, the diaphragm 301 is subjected to the biasing force of the second spring 52 alone. Because this biasing force is less than the closing force, the impact when the diaphragm 301 abuts against the valve seat 105 is weak. As a result, as in the case of the embodiment, the diaphragm 301 abuts against the valve seat 105 with a force smaller than the closing force, and the impact when the valve seat 105 is closed is reduced. This suppresses the generation of particles and the occurrence of the water hammer phenomenon caused by a sudden change in pressure in the flow path 103, and suppresses the splashing of liquid from the nozzle to which the outlet 102 is connected.

[0078] Thereafter, the lower end surface 331a of the small diameter portion 331 abuts against the upper surface 360a of the washer 360, and the biasing force of the first spring 51 is also added, pressing the diaphragm 301 against the valve seat 105, thereby bringing the fluid valve 1 into the closed state shown in Fig. 5. As a result, as in the embodiment, the diaphragm 301 closes the valve seat 105 with the necessary closing force, thereby preventing fluid from leaking from the fluid valve 1 in the closed state.

[0079] In the first modified example described above, in addition to the effects (1) and (5) obtained by the embodiment, the following effects can be obtained.

[0080] (6) The second piston 340 has a washer 360, a piston shaft 341 (fourth portion), and a piston head 342 (fifth portion). The piston shaft 341 is inserted into an insertion hole 317 formed in the first piston 330. The diaphragm 301 is attached to the piston shaft 341 via the washer 360. The piston head 342 is provided with a flange 342a having a diameter larger than the diameter of the insertion hole 317. The piston head 342 is located at a position farther away from the diaphragm 301 than the piston shaft 341, and the second spring 52 abuts against the piston head 342. This allows the second spring 52, which biases the second piston 340 having a shape different from that of the embodiment, to be located inside the first spring 51, thereby preventing the fluid valve 1 from becoming larger in size along the axis X.

[0081] (7) The outer diameter of the washer 360 is larger than the diameter of the piston shaft 341, and the first piston 330 moves relative to the second piston 340 between the piston head 342 and the washer 360. As a result, even when the first piston 330 and the second piston 340 have shapes different from those in the embodiment, it is possible to differentiate the timing at which the first piston 330 and the second piston 340 press the diaphragm 301 downward. As a result, the diaphragm 301 can be brought into contact with the valve seat 105 by the second piston 340 alone, thereby reducing impact.

[0082] (8) Even after the diaphragm 301 abuts against the valve seat 105 and the movement of the second piston 340 stops, the first piston 330 continues to move toward the valve seat 105 and abuts against the washer 360. This reduces the impact when the diaphragm 301 abuts against the valve seat 105, and enables the diaphragm 301 to close the valve seat 105 with a sufficient closing force, even when the first piston 330 and the second piston 340 have shapes different from those in the embodiment. As a result, leakage of fluid from the valve seat 105 of the fluid valve 1 in the closed state is suppressed.

[0083] <Second Modification> A fluid valve according to a second modification will be described below. Below, components similar to those of the fluid valve 1 according to the embodiment will be assigned the same reference numerals, and differences will be mainly described. Points not specifically described are the same as those in the embodiment. The fluid valve according to the second modification has a configuration that allows the amount (flow rate) of fluid flowing out of the outlet 102 to be adjusted by adjusting the stroke of the second piston 320 to change the opening of the diaphragm 301.

[0084] 7 is a cross-sectional view of the fluid valve 1 of the second modified example in a closed state, and the fluid valve 1 includes an adjustment unit 40. The adjustment unit 40 includes an operation unit 401 that is operated by a user, and a rod 402 that is attached to the operation unit 401 and extends vertically along the axis X. The rod 402 is formed with a male thread.

[0085] In order to attach the adjustment unit 40, a communication hole 403 is formed in the cover portion 202 of the cylinder portion 20, centered on the axis X, which connects the piston accommodating hole 203 with the outside of the cylinder portion 20. Furthermore, an extension portion 405 is formed in the upper portion of the flange portion 223 of the holding portion 221, extending upward with the axis X as its central axis. A through hole 404 is formed in the holding portion 221, which passes through the holding portion 221 in the up-down direction with the axis X as its center. A female thread is formed in the through hole 404.

[0086] The extension 405 of the holding part 221 is inserted into a communication hole 403 formed in the cover part 202 and fixed with a bolt or the like. Furthermore, the rod 402 of the adjustment part 40 is inserted into a through hole 404 formed in the holding part 221. In this way, the adjustment part 40 is attached to the fluid valve 1. When the adjustment part 40 is attached, the lower end 402a of the rod 402 abuts against the upper surface of the piston head part 322 of the second piston 320.

[0087] As described above, a male thread is formed on the rod 402, and a female thread is formed on the through-hole 404. Therefore, when the operating unit 401 attached to the rod 402 is rotated, the rod 402 moves upward or downward along the axis X relative to the holding unit 221, depending on the direction of the rotation. Due to the movement of the rod 402, the second piston 320, which abuts against the lower end 402a of the rod 402, also moves upward or downward along the axis X. This makes it possible to change the distance between the piston head 322 and the flange portion 223 of the holding unit 221. As a result, when the distance at which the second spring 52 is accommodated is changed by the adjustment unit 40, the biasing force of the second spring 52 on the second piston 320 is changed (adjusted).

[0088] In the second modified example described above, in addition to the effects obtained by the embodiment, the following effects can be obtained.

[0089] The movement distance of the second piston 320 can be adjusted by the adjustment unit 40. This allows the amount (flow rate) of fluid flowing out from the outlet 102 to be changed, allowing the fluid to flow out at an appropriate flow rate.

[0090] In the second modified example described above, the fluid valve 1 of the embodiment is provided with the adjustment unit 40. However, the fluid valve 1 of the first modified example may be provided with the adjustment unit 40 of the second modified example, thereby making it possible to adjust the travel distance of the second piston 340.

[0091] Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0092] 1 fluid valve, 10 flow path block, 20 cylinder portion, 30 valve mechanism, 40 adjustment portion, 50 drive mechanism, 51 first spring, 52 second spring, 101 inlet, 102 outlet, 104 valve chamber, 105 valve seat, 204 air port, 221 retaining portion, 301 diaphragm, 310, 330 first piston, 317 insertion hole, 320, 340 second piston, 321, 341 piston shaft portion, 322, 342 piston head portion, 322b, 342a flange, 323 mounting portion, 360 washer, 401 operating portion, 402 rod

Claims

a first piston disposed in the cylinder portion so as to be capable of approaching and moving away from the valve seat; a second piston to which the diaphragm is attached, the second piston having at least a portion disposed inside the first piston so as to be capable of approaching and moving away from the valve seat; and a drive mechanism for moving the first piston and the second piston in response to operating air to control opening and closing of the valve seat, the drive mechanism having a first spring for urging the first piston in a direction approaching the valve seat, and a second spring disposed inside the first spring for urging the second piston in a direction approaching the valve seat, the movement distance of the first piston being longer than the movement distance of the second piston, when the operating air is exhausted, the first piston and the second piston move in a direction approaching the valve seat due to the biasing force of the first spring and the second spring, and when the diaphragm abuts against the valve seat, the movement of the second piston stops, and only the first piston moves in the direction approaching the valve seat due to the biasing force of the first spring and abuts against the second piston, pressing the diaphragm against the valve seat.

2. A fluid valve as described in claim 1, further comprising a retaining portion that is provided within the cylinder portion at a position farther from the valve seat than the first piston and the second piston and that retains the drive mechanism, the second piston having a first portion inserted into an insertion hole formed in the first piston, a second portion provided with a flange having a diameter larger than the diameter of the insertion hole and attached to the first portion at a position farther from the valve seat, and a third portion to which the diaphragm is attached, the inner diameter of the first piston being larger than the diameter of the insertion hole and the diameter of the flange, the second portion protruding in a direction away from the valve seat beyond the bottom surface of the first piston, one side of the first spring abutting against the retaining portion and the other side abutting against the bottom surface of the first piston, and one side of the second spring abutting against the retaining portion and the other side abutting against the second portion.

3. A fluid valve as claimed in claim 2, wherein said first piston moves relative to said second piston between said second portion and said third portion.

4. A fluid valve as described in claim 3, wherein the first piston continues to move in a direction approaching the valve seat and abuts against the third portion even after the diaphragm abuts against the valve seat and the movement of the second piston stops, thereby pressing the diaphragm against the valve seat.

5. A fluid valve as claimed in claim 1, further comprising: a retaining portion for retaining the drive mechanism, the retaining portion being disposed within the cylinder portion at a position farther from the valve seat than the first piston and the second piston; the second piston having a washer, a fourth portion inserted into an insertion hole formed in the first piston and to which the diaphragm is attached via the washer, and a fifth portion having a flange having a diameter larger than the diameter of the insertion hole and formed at a position farther from the valve seat, the inner diameter of the first piston being larger than the diameter of the insertion hole and the diameter of the flange, the fifth portion protruding in a direction away from the valve seat beyond the bottom surface of the first piston, one side of the first spring abutting against the retaining portion and the other side abutting against the bottom surface of the first piston, and one side of the second spring abutting against the retaining portion and the other side abutting against the fifth portion.

6. A fluid valve as claimed in claim 5, wherein an outer diameter of said washer is greater than a diameter of said fourth portion, and said first piston moves relative to said second piston between said fifth portion and said washer.

7. A fluid valve as claimed in claim 6, wherein the first piston continues to move in a direction approaching the valve seat and abuts against the washer even after the diaphragm abuts against the valve seat and the movement of the second piston stops, thereby pressing the diaphragm against the valve seat.

8. A fluid valve according to any one of claims 1 to 7, further comprising an adjustment section for adjusting the travel distance of the second piston.

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