Fluid valve

Abstract

A fluid valve 1 comprises: a valve mechanism 30 including a diaphragm 301, which is disposed so as to be capable of abutting on and separating from a valve seat 105, and a piston 302 to which the diaphragm 301 is attached; a drive mechanism 50 for moving the valve mechanism 30; and a first speed control part 40 for controlling a moving speed of the valve mechanism 30 moving in a closing direction. The first speed control part 40 includes: a first outer peripheral part 404 and a second outer peripheral part 405 which have different diameters and are formed on a first outer peripheral side surface 320 of the piston 302; a first connecting peripheral part 406; and a plurality of first ball members 401 that make point contact with the first outer peripheral side surface 320 of the piston 302. When the valve mechanism 30 moves in the closing direction, the first ball members 401 relatively move from the second outer peripheral part 405 to the first outer peripheral part 404 through the first connecting peripheral part 406 while making point contact with the first outer peripheral side surface 320, thereby reducing the moving speed of the valve mechanism 30.

Description

Fluid Valve

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

[0002] In pilot valves that control fluid, water hammer can occur when the piston suddenly closes the valve. Water hammer is a phenomenon in which the kinetic energy of the fluid on the output port side is converted into pressure energy, creating negative pressure, causing the fluid to be pushed back by this negative pressure, generating impact noise and vibration.

[0003] Patent Document 1 discloses a pilot valve with a mechanism for reducing the occurrence of water hammer. In this patent document, the piston comes into contact with an elastic member such as a rubber cushion just before the diaphragm seats on the valve seat, thereby reducing the piston speed when the valve closes. By reducing the piston speed, the impact caused by the piston when seating is mitigated, and the valve does not close suddenly, thereby suppressing the occurrence of water hammer.

[0004] Japanese Patent Application Laid-Open No. 2005-233298

[0005] In Patent Document 1, the impact of the piston is absorbed by an elastic member, which requires the elastic member to be thick. However, if the thickness of the elastic member is increased, the biasing force of the spring that moves the piston is also used to compress the elastic member, which weakens the force with which the piston closes the valve, and there is a risk of fluid leakage from the valve seat when the valve is closed and a decrease in the durability of the diaphragm.

[0006] In one embodiment, the fluid valve includes a flow path block having a valve chamber with a valve seat formed therein between a fluid inlet and an outlet, a diaphragm disposed in the valve chamber so as to be movable toward and away from the valve seat, a piston to which the diaphragm is attached and disposed in a cylinder section so as to be movable toward and away from the valve seat, a drive mechanism that moves the valve mechanism in response to working air supplied or discharged from an air port to control opening and closing of the valve seat, and a first speed control unit that controls the speed of the valve mechanism moving in a closing direction to close the valve seat. The first speed control unit includes first and second outer circumferential portions having different diameters formed on a first outer circumferential side surface of the piston, a first connecting circumferential portion that is an inclined surface connecting the first and second outer circumferential portions, and a plurality of first spherical members disposed in point contact with the first outer circumferential side surface of the piston. The diameter of the first outer circumferential portion is larger than the diameter of the second outer circumferential portion. The first speed control unit reduces the movement speed of the valve mechanism by causing the first spherical member to move relatively from the second outer periphery through the first connecting periphery to the first outer periphery while in point contact with the first outer periphery side surface when the valve mechanism moves in the closing direction.

[0007] According to the present invention, the speed of movement of the valve mechanism is controlled by the outer peripheral surface of the piston and the spherical member, thereby making it possible to mitigate the impact of the piston while maintaining the durability of the diaphragm and preventing fluid leakage (pressure resistance) from the valve seat when the valve is closed.

[0008] 1 is a cross-sectional view of a fluid valve of an embodiment in an open state; FIG. 2 is a cross-sectional view of a fluid valve of a closed state; FIG. 3 is a cross-sectional view showing an enlarged portion of the fluid valve of an embodiment in an open state; FIG. 4 is a cross-sectional view showing an enlarged portion of the fluid valve of a closed state; FIG. 5 is a diagram showing the relationship between the flow rate of fluid flowing through the fluid valve of an embodiment and time, and the relationship between the flow rate of fluid flowing through a valve of a comparative example and time; FIG. 6 is a cross-sectional view of a fluid valve of a modified example in a closed state; FIG. 7 is a diagram showing the relationship between the flow rate of fluid flowing through the fluid valve of a modified example and time, and the relationship between the flow rate of fluid flowing through a valve of a comparative example and time; FIG. 8 is a cross-sectional view showing an enlarged portion of another example fluid valve of a modified example.

[0009] A fluid valve according to an embodiment of the present invention will be described in detail below 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.

[0010] <Overall Configuration> Figures 1 and 2 are cross-sectional views of a fluid valve 1. Figure 1 shows the fluid valve 1 in an open state, and Figure 2 shows the fluid valve 1 in a closed state. Figure 3 is an enlarged cross-sectional view of a portion of the fluid valve 1 shown in Figure 1, and Figure 4 is an enlarged cross-sectional view of a portion of the fluid valve 1 shown in Figure 2. The open state is a state in which fluid can flow through the fluid valve 1, and the closed state is a state in which fluid flow through the fluid valve 1 is restricted.

[0011] The fluid valve 1 is configured to be able to transition from an open state in which a fluid flows through the fluid valve 1 as shown in Figures 1 and 3 to a closed state as shown in Figures 2 and 4. The fluid valve 1 is also configured to be able to transition from the closed state as shown in Figures 2 and 4 to the open state as shown in Figures 1 and 3.

[0012] The fluid valve 1 includes a flow path block 10, a cylinder section 20, a valve mechanism 30, and a first speed control section 40. The cylinder section 20 is provided with a drive mechanism 50 that drives the valve mechanism 30. 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, 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 portion 20> The cylinder portion 20 is disposed above the flow path block 10 via an adjustment plate 400, which will be described in detail later. The cylinder portion 20 is formed, for example, from a resin material. The cylinder portion 20 is formed in a cylindrical shape with the axis line X as its central axis. The cylinder portion 20 has a main body portion 201 and a cover portion 202 that is fixed to the upper part of the main body portion 201 by a fastening screw or the like.

[0016] The main body 201 has a cylindrical shape and is formed with a piston accommodating hole 203 that extends in the vertical direction around the axis X. 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] The inner peripheral surface of the main body 201 is formed with a housing 205 that houses some of the components constituting the first speed control unit 40 (described later). The housing 205 is formed by an annular portion 206 and a cylindrical portion 207. The annular portion 206 has an inner diameter smaller than the inner diameter of the main body 201 (i.e., the diameter of the piston accommodating hole 203). The outer peripheral end of the annular portion 206 is connected to the inner peripheral surface of the main body 201. The cylindrical portion 207 has a cylindrical shape with an inner diameter equal to the inner diameter of the annular portion 206. The cylindrical portion 207 is connected at its upper end to the inner peripheral end of the annular portion 206 and extends downward in the vertical direction. As a result, a gap is formed between the cylindrical portion 207 and the inner peripheral surface of the main body 201, and some of the components constituting the first speed control unit 40 are housed in this gap.

[0018] <Valve mechanism 30> The valve mechanism 30 has a diaphragm 301 and a piston 302. 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 separates from the valve seat 105, as described below.

[0019] 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.

[0020] 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 a mounting surface 110 formed inside the flow path block 10 and an adjustment plate 400, which will be described later.

[0021] The piston 302 is accommodated in a piston accommodation hole 203 formed in the main body 201 of the cylinder 20 so as to be movable back and forth (advance and retreat) in the vertical direction along the axis X, i.e., so as to be able to move toward and away from the valve seat 105. The piston 302 is formed, for example, from a metal material or the like, and has a piston shaft 310 and a piston head 311. The piston shaft 310 extends in the vertical direction with the axis X as its central axis. The diameter of the piston shaft 310 is approximately equal to the inner diameter of the accommodation portion 205 formed in the main body 201 described above.

[0022] A groove 312 is formed along the outer periphery of first outer peripheral side surface 320 of piston shaft portion 310, and an elastic member 315 such as a packing is housed in groove 312. In addition, a first outer peripheral portion 404, a second outer peripheral portion 405, and a first connecting peripheral portion 406 that constitute a first speed control portion 40 (described later) are formed below first outer peripheral side surface 320 of piston shaft portion 310.

[0023] An attachment portion 313 having a female thread extending in the vertical direction is provided at the lower end of the piston shaft portion 310. This attachment portion 313 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 piston 302.

[0024] The piston head 311 is provided on the upper part of the piston shaft 310. The piston head 311 has a cylindrical shape extending in the vertical direction with the axis X as its central axis. The outer diameter of the piston head 311 is larger than the diameter of the piston shaft 310 and is approximately equal to the diameter of the piston accommodating hole 203. The piston 302 is accommodated in the piston accommodating hole 203 so that the piston head 311 is positioned above the accommodating portion 205. A groove 314 is formed along the outer periphery on the outer peripheral side surface of the piston head 311, and an elastic member 316 such as a packing is accommodated in the groove 314.

[0025] <First Speed ​​Control Unit 40> The first speed control unit 40 controls the moving speed of the piston 302 when the fluid valve 1 transitions between the open state and the closed state. As shown in Figures 3 and 4, the first speed control unit 40 has an adjusting plate 400, a first spherical member 401, a ball holding portion 402, an elastic member 403, and a first outer circumferential portion 404, a second outer circumferential portion 405, and a first connecting circumferential portion 406 formed on a part of the first outer circumferential side surface 320 of the piston shaft portion 310 of the piston 302.

[0026] The adjusting plate 400 is formed of, for example, a metal material or a resin material. The adjusting plate 400 is an annular member having an opening with its central axis aligned with the axis X. As described above, the adjusting plate 400 is disposed between the flow path block 10 and the main body 201 of the cylinder section 20. The inner diameter of the adjusting plate 400 is smaller than the diameters of the piston accommodating hole 203 and the valve chamber 104, and larger than the diameter of the piston shaft 310. Therefore, a portion of the adjusting plate 400 forms a protruding annular portion 410 that protrudes toward the axis X from the inner circumferential side surface of the flow path block 10 and the inner circumferential side surface of the main body 201 of the cylinder section 20. A lower surface (lower surface) 411 of the protruding annular portion 410 abuts against an upper surface (upper surface) 305a of the outer circumferential portion 305 of the diaphragm 301. In other words, the diaphragm 301 is fixed in place by the outer peripheral portion 305 being sandwiched between the lower surface 411 of the protruding annular portion 410 and the mounting surface 110 of the flow path block 10 in the vertical direction.

[0027] The first spherical members 401 are formed of, for example, a metal material or ceramic. The first spherical members 401 are arranged on an upper surface (top surface) 412 of the protruding annular portion 410 of the adjusting plate 400. A plurality of first spherical members 401 are arranged along a circumference centered on the axis X. Specifically, each of the plurality of first spherical members 401 is arranged in point contact with the first outer peripheral side surface 320 of the piston shaft portion 310. Each first spherical member 401 is rotatably held on the top surface 412 by a ball holding portion 402 (described later) and the first outer peripheral side surface 320. In other words, the adjusting plate 400 is a support portion that supports the first spherical members 401 from the flow path block 10 side (lower side).

[0028] The ball holding portion 402 is formed, for example, from a metal material or a resin material. The ball holding portion 402 is an annular member with its central axis aligned with the axis X. The outer diameter of the ball holding portion 402 is approximately equal to the diameter of the piston accommodating hole 203. A contact portion 421 that makes point contact with the first ball member 401 is formed near the lower end of the ball holding portion 402. The contact portion 421 is formed by a protruding flat surface 422 that protrudes toward the axis X from the inner peripheral side surface of the ball holding portion 402 and a sloped surface 423 that connects the protruding flat surface 422 to the lower end of the ball holding portion 402. The sloped surface 423 is a tapered surface formed so that the distance from the axis X gradually increases from the upper end to the lower end. In other words, the sloped surface 423 faces the first ball member 401 and is a surface that is inclined non-parallel to the vertical direction (closing direction). This inclined surface 423 comes into point contact with the first spherical member 401 from above.

[0029] A portion of the ball holding portion 402 is accommodated in the accommodation portion 205 formed on the inner circumferential side surface of the main body portion 201. Specifically, the side surface of the ball holding portion 402 above the contact portion 421 is accommodated in a gap formed between the inner circumferential side surface of the main body portion 201 and the cylindrical portion 207 of the accommodation portion 205. In addition, an elastic member 403, such as a coil spring or an O-ring made of rubber, is disposed between the protruding flat surface 422 that forms the contact portion 421 of the ball holding portion 402 and the annular portion 206 of the accommodation portion 205. That is, the upper end of the elastic member 403 abuts against the annular portion 206 of the cylinder portion 20, and the lower end abuts against the protruding flat surface 422. As a result, the ball holding portion 402 is biased downward by the elastic member 403.

[0030] As the ball holding portion 402 is biased downward, a force is applied to the first spherical member 401 by the elastic member 403 via the inclined surface 423. Because the inclined surface 423 is a tapered surface formed on the contact portion 421, a force is applied to the first spherical member 401 by the inclined surface 423 in a direction intersecting the axis X, i.e., toward the first outer peripheral side surface 320 of the piston shaft portion 310, which will be described later. For this reason, it can be said that the ball holding portion 402 rotatably holds the first spherical member 401 while biasing it against the first outer peripheral side surface 320 of the piston 302.

[0031] The force with which the ball holding portion 402 urges the first ball member 401 against the first outer peripheral side surface 320 is determined by the inclination angle of the inclined surface 423 and the elastic force of the elastic member 403. In other words, by appropriately changing the inclination angle of the inclined surface 423 and the elastic force of the elastic member 403, the urging force on the first ball member 401 can be set to a desired value.

[0032] The first outer periphery 404, the second outer periphery 405, and the first connecting periphery 406 are formed on the first outer periphery side surface 320 of the piston shaft portion 310. The first outer periphery 404 and the second outer periphery 405 have different diameters, and the first outer periphery 404 is formed above the second outer periphery 405. The first connecting periphery 406 is formed between the first outer periphery 404 and the second outer periphery 405 and connects the first outer periphery 404 and the second outer periphery 405, which have different diameters. Specifically, the diameter of the first outer periphery 404 is larger than the diameter of the second outer periphery 405. Therefore, the first connecting periphery 406 is a tapered surface (inclined surface) formed so that the diameter gradually increases from the bottom to the top.

[0033] The first outer circumferential portion 404, the second outer circumferential portion 405, and the first connecting circumferential portion 406 are in point contact with the first spherical member 401, which receives force from the inclined surface 423. Specifically, when the fluid valve 1 is in the open state, the second outer circumferential portion 405 is in point contact with the first spherical member 401. When the fluid valve 1 is in the closed state, the first outer circumferential portion 404 is in point contact with the first spherical member 401. When the fluid valve 1 transitions from the open state to the closed state, the first spherical member 401 moves relatively along the first outer circumferential side surface 320, passing from the second outer circumferential portion 405 to the first outer circumferential portion 404, passing through the first connecting circumferential portion 406.

[0034] <Drive mechanism 50> The drive mechanism 50 is an elastic member such as a coil spring, and is housed in a housing portion 501 formed in the piston head portion 311. The housing portion 501 is an opening that opens on the upper side of the piston head portion 311. The lower end of the drive mechanism 50 housed in the housing portion 501 abuts against a lower surface 502 of the housing portion 501, and the upper end abuts against an upper end surface 202a of the cover portion 202 of the cylinder portion 20. In this way, the drive mechanism 50 urges the piston 302 downward.

[0035] As will be described later, when working air such as compressed air is exhausted from the piston housing hole 203, the piston 302 moves downward due to the biasing force of the drive mechanism 50. That is, the diaphragm 301 abuts against the valve seat 105, thereby closing the valve seat 105. On the other hand, when working air is supplied to the piston housing hole 203, the piston 302 moves upward against the biasing force of the drive mechanism 50. 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 moves the valve mechanism 30 in accordance with the working air supplied or exhausted from the air port 204, thereby controlling the opening and closing of the valve seat 105.

[0036] <Operation of Fluid Valve 1> When the fluid valve 1 is in the open state as shown in Figure 1, operating air such as compressed air is supplied to the piston housing bore 203 from the air port 204. The pressure inside the piston housing bore 203, which is increased by the supply of fluid, moves the piston 302 in the separating direction along the axis X against the downward biasing force of the drive mechanism 50. Then, as shown in Figure 1, the upper surface 321 of the piston head 311 abuts against the lower end surface 202b of the cover portion 202 of the cylinder portion 20. This restricts the valve mechanism 30 from moving further in the separating direction.

[0037] As the piston 302 moves upward, the seal portion 303 of the diaphragm 301 attached to the lower end of the piston shaft portion 310 also moves upward. As a result, the seal portion 303 is spaced apart from the valve seat 105. Furthermore, as the piston 302 moves upward, the first spherical member 401 comes into point contact with the second outer periphery 405 formed on the first outer periphery side surface 320 of the piston 302.

[0038] <Transition from Open State to Closed State> The transition from the open state shown in FIGS. 1 and 3 to the closed state shown in FIGS. 2 and 4 will be described. In the open state, fluid such as compressed air is discharged from the piston housing bore 203 via the air port 204. When the compressed air is discharged and the pressure in the piston housing bore 203 decreases, the piston 302 begins to move in the closing direction (downward) along the axis X due to the biasing force of the drive mechanism 50. This movement of the piston 302 changes the positional relationship between the piston shaft portion 310 and the first spherical member 401. That is, as the piston shaft portion 310 moves downward relative to the first spherical member 401, the position of point contact of the first spherical member 401 on the first outer circumferential side surface 320 shifts from the second outer circumferential portion 405 to the first connecting circumferential portion 406.

[0039] As described above, the first connecting circumferential portion 406 has a tapered slope with a diameter that increases toward the upper side. Therefore, the force acting on the first spherical member 401 from the first connecting circumferential portion 406 toward the outside in the radial direction increases. Furthermore, the first spherical member 401 is subjected to a force component of the biasing force of the elastic member 403 directed in the direction of the axis X via the ball holding portion 402. This force acts as a sliding resistance on the piston 302 via the first spherical member 401.

[0040] As the piston 302 moves downward, the force acting on the first spherical member 401 from the first connecting circumferential portion 406, which is a tapered inclined surface, increases, causing the first spherical member 401 to rotate radially outward against the biasing force of the elastic member 403. In other words, the piston 302 moves downward, pushing the first spherical member 401 aside. At this time, the ball holding portion 402 moves upward in conjunction with the rotational movement of the first spherical member 401, increasing the force that the first spherical member 401 receives from the elastic member 403. In other words, the sliding resistance that the piston 302 receives from the first spherical member 401 increases. As a result, the downward movement of the valve mechanism 30 is restricted, and the downward movement speed of the valve mechanism 30 decreases.

[0041] As the valve mechanism 30 moves further downward with the moving speed reduced, the seal portion 303 of the diaphragm 301 attached to the lower end of the piston shaft portion 310 reaches the valve seat 105. At this time, since the piston shaft portion 310 has moved downward relative to the first spherical member 401, the position at which the first spherical member 401 makes point contact on the first outer peripheral side surface 320 shifts from the first connecting peripheral portion 406 to the first outer peripheral portion 404.

[0042] When the first spherical member 401 is in point contact with the first outer periphery 404, the sliding resistance experienced by the piston 302 is small, and therefore the piston 302 moves downward at a reduced speed when the first connecting periphery 406 is in point contact with the first spherical member 401. In this way, when the valve mechanism 30 moves in the closing direction, the first spherical member 401 moves relatively from the second outer periphery 405 to the first outer periphery 404 via the first connecting periphery 406, thereby reducing the moving speed of the valve mechanism 30.

[0043] With the moving speed reduced, the valve mechanism 30 stops at a position where the lower end of the piston shaft 310 presses the diaphragm 301 downward. At this time, the piston shaft 310 of the piston 302, which is biased downward by the biasing force of the drive mechanism 50, presses the seal portion 303 of the diaphragm 301 against and abuts the valve seat 105, closing the valve seat 105. In other words, the fluid valve 1 transitions to the closed state shown in FIGS. 2 and 4.

[0044] As described above, when transitioning from the open state to the closed state, the first spherical member 401, while in point contact with the first outer peripheral side surface 320 of the piston 302, moves relatively from the second outer peripheral portion 405 through the first connecting peripheral portion 406 to the first outer peripheral portion 404. As a result, the valve mechanism 30 starts moving in the closing direction. The piston 302 then stops moving at a reduced speed and presses the diaphragm 301 that has reached the valve seat 105. In other words, the first speed control unit 40 controls the moving speed of the piston 302 when the diaphragm 301, having moved in the closing direction, abuts against the valve seat 105. As a result, after starting to move, the valve mechanism 30 moves at a low speed just before the diaphragm 301 abuts against the valve seat 105. This allows the fluid valve 1 to close the valve seat 105 in a short time after starting to operate and reduce the impact associated with the operation of the valve mechanism 30 when closing the valve seat 105.

[0045] Compared to the comparative example, which has a configuration in which the impact when the valve closes is alleviated by narrowing the exhaust volume from the air port 204 through meter-out control by the speed controller and slowing down the moving speed of the piston 302, in this embodiment, even when the exhaust volume of the speed controller is increased, the impact when the valve closes is alleviated and the valve seat 105 is closed in a short time.

[0046] 5 shows the relationship between time and the flow rate of fluid flowing through the fluid valve 1 of the present embodiment, and the relationship between time and the flow rate of fluid flowing through a valve of a comparative example. In FIG. 5, the vertical axis represents flow rate, and the horizontal axis represents time. In FIG. 5, L1 shown by a solid line represents the fluid valve 1 of the present embodiment, and L2 shown by a dashed line represents the valve of the comparative example.

[0047] 5, in the valve of the comparative example, it takes time T10 from when the valve mechanism starts moving in the closing direction at time t1 until it reaches the closed state. In contrast, in the fluid valve 1 of this embodiment, the movement speed is fast immediately after the valve mechanism 30 starts moving at time t1, so it reaches the closed state in time T11, which is shorter than time T10. This makes it possible to reduce the amount of fluid that flows wasted until the valve seat 105 is closed.

[0048] Furthermore, since the impact when the valve seat 105 is closed is reduced, it is possible to suppress the generation of particles and the occurrence of the water hammer phenomenon caused by a sudden change in pressure inside the flow path 103. This prevents the liquid from splashing out of the nozzle to which the outlet 102 is connected.

[0049] <Transition from Closed State to Open State> Next, a case where the fluid valve 1 in the closed state shown in Figures 2 and 4 transitions to the open state will be described. When the fluid valve 1 is in the closed state, the supply of operating air, such as compressed air, to the piston housing bore 203 via the air port 204 begins. Due to the increased pressure in the piston housing bore 203 caused by the supply of operating air, the piston 302 begins to move in the separation direction (upward) along the axis X against the downward biasing force of the drive mechanism 50. The diaphragm 301 also moves upward as the piston 302 moves upward. That is, the seal portion 303 of the diaphragm 301 begins to separate from the valve seat 105.

[0050] The first outer peripheral side surface 320 of the piston 302 moves upward while remaining in point contact with the first spherical member 401. When the upper surface 321 of the piston head 311 abuts against the lower end surface 202b of the cover portion 202 of the cylinder portion 20, the upward movement of the piston 302 stops. As a result, the seal portion 303 of the diaphragm 301, which has moved upward together with the piston 302, is held in a position spaced apart from the valve seat 105, and the valve seat 105 is placed in an open state. In other words, the fluid valve 1 transitions to the open state shown in FIGS. 1 and 3.

[0051] According to the above-described embodiment, at least one of the following advantageous effects can be obtained.

[0052] (1) The first speed control unit 40 included in the fluid valve 1 controls the movement speed of the valve mechanism 30 moved in the closing direction to close the valve seat 105 by the drive mechanism 50. The first speed control unit 40 includes a first outer circumferential portion 404 and a second outer circumferential portion 405 of different diameters formed on the first outer circumferential side surface 320 of the piston 302, a first connecting circumferential portion 406 that is an inclined surface connecting the first outer circumferential portion 404 and the second outer circumferential portion 405, and a plurality of first spherical members 401 arranged in point contact with the first outer circumferential side surface 320 of the piston 302. When the valve mechanism 30 moves in the closing direction, the first spherical members 401 move relatively from the second outer circumferential portion 405 through the first connecting circumferential portion 406 to the first outer circumferential portion 404 while in point contact with the first outer circumferential side surface 320, thereby causing the first speed control unit 40 to slow down the movement speed of the valve mechanism 30.

[0053] As a result, as the valve mechanism 30 moves in the closing direction, the position at which the first spherical member 401 makes point contact with the first outer peripheral side surface 320 changes, changing the magnitude of the sliding resistance acting on the piston 302 and thereby slowing down the movement speed of the valve mechanism 30. In other words, immediately after starting to move in the closing direction, the piston 302 seats at a reduced movement speed and presses the diaphragm 301 downward. As a result, the valve seat 105 is closed in a short time after the valve mechanism 30 starts to operate in the open state, and the impact caused by the valve mechanism 30 when closing the valve seat 105 can be reduced.

[0054] Since the impact when the valve seat 105 closes 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 suppresses the splashing of liquid from the nozzle to which the outlet 102 is connected. Since the splashing of liquid from the nozzle is suppressed, the liquid is prevented from adhering to an unintended position on the object onto which the liquid is to be dropped (e.g., a wafer, etc.), which would result in the object being defective. Furthermore, since the splashing of liquid is suppressed, an amount of liquid different from the desired amount is prevented from being dropped onto the object, which contributes to maintaining the quality of the object.

[0055] In particular, unlike configurations that use elastic members such as rubber cushions to absorb impact, the fluid valve 1 of this embodiment prevents a loss of the force with which the piston 302 presses the diaphragm 301 after seating, and prevents a weakening of the force closing the valve seat 105. This makes it possible to prevent fluid from leaking from the valve seat when the fluid valve 1 is closed, without having to increase the size of the fluid valve 1 and the force that closes the valve.

[0056] In addition, if an elastic member is used to absorb impact, the elastic member must be thick. In contrast, in the fluid valve 1 of this embodiment, the first outer peripheral surface 320 of the piston 302 and the first spherical member 401 reduce the movement speed of the valve mechanism 30, so there is no need to secure space to accommodate the elastic member, and the fluid valve 1 is prevented from becoming larger.

[0057] (2) The first speed control unit 40 has a ball holding unit 402 that rotatably holds the first spherical member 401 while biasing it against the first outer peripheral side surface 320 of the piston 302. Specifically, the ball holding unit 402 is biased in the closing direction by an elastic member 403. The ball holding unit 402 faces the first spherical member 401 and has an inclined surface 423 that is not parallel to the closing direction (up and down direction), and is in point contact with the first spherical member 401 at the inclined surface 423. This maintains the first spherical member 401 in point contact with the first outer peripheral side surface 320, and the movement speed of the valve mechanism 30 is controlled by the first spherical member 401 and the first outer peripheral side surface 320, whose relative positions change as the piston 302 moves.

[0058] (3) The piston 302 is made of a metal material or the like, and the first spherical member 401 is made of a metal material or ceramic. In a configuration in which the movement speed of the valve mechanism 30 is controlled using an elastic member such as a rubber cushion, there is a risk that the shock absorbing capacity will change due to deterioration of the elastic member over time. In contrast, in this embodiment, changes in the shock absorbing capacity due to deterioration over time are suppressed.

[0059] <Modifications> The fluid valve 1 of the above-described embodiment may be provided with a configuration for controlling the speed of movement of the valve mechanism 30 in the separating direction (upward) when transitioning from the closed state to the open state.

[0060] 6 is a cross-sectional view of the fluid valve 1 in the closed state in the modified example. In the following description, the same reference numerals are used to designate components that are the same or substantially the same as those in the fluid valve 1 of the embodiment. Differences from the fluid valve 1 of the embodiment will be mainly described, and those that are not specifically described are the same as those in the fluid valve 1 of the embodiment described above.

[0061] The fluid valve 1 further includes a second speed control unit 60. The second speed control unit 60 has a cover unit 601, a rod 602, a second spherical member 603, and a spherical holder 604. The cover unit 601 is formed in a cylindrical shape with the axis X as its central axis. The cover unit 601 is disposed on top of the cover unit 202 of the cylinder unit 20. The cover unit 601 accommodates a portion of the rod 602, the second spherical member 603, and the spherical holder 604. An opening 220 with the axis X as its central axis is formed in the upper end surface 202a of the cover unit 202 of the cylinder unit 20.

[0062] The rod 602 is formed, for example, from a metal material or the like, and extends in the vertical direction around the axis X as its central axis. The lower end of the rod 602 is inserted into a mounting hole 311a formed in the piston head 311, thereby fixing the rod 602 to the piston 302. Therefore, the rod 602 moves vertically along with the vertical movement of the piston 302. The vicinity of the upper end of the rod 602 is inserted into the opening 220 of the cover portion 202 and protrudes upward beyond the cover portion 202. That is, the portion of the rod 602 that protrudes upward from the cover portion 202 is housed within the cover portion 601, and the other portion is housed within the piston accommodating hole 203. Because the rod 602 includes a portion that is housed within the piston accommodating hole 203, the diameter of the rod 602 is smaller than the inner diameter of the drive mechanism 50, which is a coil spring.

[0063] A third outer circumferential portion 622, a fourth outer circumferential portion 623, and a second connecting circumferential portion 624 are formed on a second outer circumferential side surface 621 of the portion of the rod 602 that is housed in the cover portion 601. The third outer circumferential portion 622 and the fourth outer circumferential portion 623 have different diameters, and the third outer circumferential portion 622 is formed above the fourth outer circumferential portion 623. The second connecting circumferential portion 624 is formed between the third outer circumferential portion 622 and the fourth outer circumferential portion 623 and connects the third outer circumferential portion 622 and the fourth outer circumferential portion 623, which have different diameters. Specifically, the diameter of the third outer circumferential portion 622 is smaller than the diameter of the fourth outer circumferential portion 623. Therefore, the second connecting circumferential portion 624 is a tapered surface formed so that the diameter gradually increases from top to bottom.

[0064] The second spherical member 603 is formed of, for example, a metal material or ceramic. The second spherical member 603 is disposed on the cover portion 202. A plurality of second spherical members 603 are disposed along a circumference centered on the axis X. Specifically, each of the plurality of second spherical members 603 is disposed in point contact with the second outer peripheral side surface 621 of the rod 602. Each second spherical member 603 is rotatably held by the rod 602 and a ball holding portion 604 (described later). The second spherical member 603 is in point contact with the second connecting peripheral portion 624 of the second outer peripheral side surface 621 when the fluid valve 1 is in the closed state, and in point contact with the fourth outer peripheral portion 623 when the fluid valve 1 is in the open state.

[0065] The ball holding portion 604 is formed, for example, from a metal material or a resin material. The ball holding portion 604 is formed in a cylindrical shape centered on the axis X. A protrusion 642 and a contact portion 643 are formed on the ball holding portion 604. The protrusion 642 protrudes radially outward from the outer circumferential side surface near the lower end of the ball holding portion 604. The contact portion 643 is a tapered slope formed by cutting out the lower end of the inner circumferential side surface of the ball holding portion 604. Specifically, the inner diameter of the contact portion 643 gradually increases from top to bottom. The contact portion 643 makes point contact with the second ball member 603 from above.

[0066] An elastic member 625, such as a coil spring, is disposed on an upper surface 642a of the protrusion 642. The upper end of the elastic member 625 is fixed to the lower surface 601a of the cover portion 601, and the lower end is fixed to the surface 642a of the protrusion 642. As a result, the ball holding portion 604 is biased downward by the elastic member 625. As the ball holding portion 604 is biased downward, a force from the elastic member 625 acts on the second ball member 603 via the contact portion 643, which is an inclined surface. Because the contact portion 643 has a tapered surface, a force acts on the second ball member 603 by the contact portion 643 in a direction intersecting the axis X toward the axis X, i.e., toward the second outer peripheral side surface 621 of the rod 602.

[0067] The operation of the modified fluid valve 1 having the above configuration when it transitions from a closed state to an open state will now be described. In this case, as in the embodiment, when the supply of operating air such as compressed air to the piston accommodating hole 203 begins via the air port 204, the piston 302 begins to move upward along the axis X.

[0068] As the piston 302 moves upward, the rod 602 also moves upward, and thus the rod 602 moves upward relative to the second spherical member 603. Because the second connecting circumferential portion 624 has a tapered slope whose diameter increases toward the bottom, the sliding resistance of the second spherical member 603 to the rod 602 increases as the rod 602 moves upward. Therefore, the upward movement of the piston 302 to which the rod 602 is attached is restricted, and the valve mechanism 30 starts to move upward at a low speed.

[0069] Furthermore, when the rod 602 moves upward together with the upward movement of the valve mechanism 30, the rod 602 moves upward relative to the second spherical member 603. As a result, the position of point contact of the second spherical member 603 on the second outer peripheral side surface 621 shifts from the second connecting peripheral portion 624 to the third outer peripheral portion 622. At this time, the diaphragm 301 also moves away from the valve seat 105 and moves upward together with the piston 302.

[0070] When the second spherical member 603 makes point contact with the third outer periphery 622, the rod 602 experiences small sliding resistance, and the valve mechanism 30 moves upward at a high speed immediately after starting to move upward. As the valve mechanism 30 moves in the separating direction, the second spherical member 603 moves relatively from the second connecting periphery 624 to the fourth outer periphery 623, increasing sliding resistance and causing the valve mechanism 30 to move upward at a slower speed. When the upper surface 321 of the piston head 311 abuts against the lower end surface 202b of the cover portion 202 of the cylinder portion 20, the upward movement of the valve mechanism 30 stops. This causes the fluid valve 1 to transition from the closed state to the open state.

[0071] As described above, when transitioning from the closed state to the open state, the valve mechanism 30 moves upward at a slow speed as the second spherical member 603 moves relatively from the second connecting circumferential portion 624 to the fourth outer circumferential portion 623. This prevents a sudden increase in the amount of fluid flowing through the flow path 103, resulting in a temporary overshoot-like increase in the flow rate. In other words, it becomes possible to discharge a highly stable fluid from the outlet 102, with the generation of bubbles, particles, etc. suppressed.

[0072] When the valve mechanism 30 is shifted from the open state to the closed state, the downward movement speed of the valve mechanism 30 is controlled in the same manner as in the embodiment.

[0073] 7 shows the relationship between time and the flow rate of fluid flowing through the modified fluid valve 1, and the relationship between time and the flow rate of fluid flowing through a comparative valve that does not control the movement speed of the valve mechanism 30 when transitioning to an open state. In FIG. 7, the vertical axis represents flow rate and the horizontal axis represents time. In FIG. 7, L3 shown by a solid line represents the modified fluid valve 1, and L4 shown by a dashed line represents the comparative valve.

[0074] 7, in the valve of the comparative example, it takes time T20 from the time t0 when the valve mechanism starts to move in the separating direction until the flow rate of the fluid flowing through the flow path 103 reaches a maximum. At this time, an overshoot R1 occurs, in which the amount of fluid flowing through the flow path 103 temporarily increases. It takes time T21 from the time the overshoot R1 occurs until the amount of fluid flowing through the flow path 103 stabilizes.

[0075] In contrast, in the fluid valve 1 of the modified example, it takes a time T22, which is longer than the time T20, from when the valve mechanism 30 starts moving at time t0 until the flow rate of the fluid flowing through the flow path 103 reaches its maximum. At this time, an overshoot R2 occurs. However, because the movement speed of the valve mechanism 30 is slow immediately after it starts moving, the amount of overshoot R2 that occurs is kept smaller than the overshoot R1 that occurs in the comparative example. Furthermore, because the overshoot R2 is kept small, the time required for the amount of fluid flowing through the flow path 103 to stabilize is time T23, which is shorter than time T21. Therefore, it is possible to shorten the time until the fluid flowing out of the outlet 102 achieves highly stable performance.

[0076] The relationship between the flow rate of the fluid and time after time t1 is the same as in the embodiment shown in FIG.

[0077] In the above-described modified example, in addition to the effects (1) to (3) obtained by the embodiment, the following effects can be obtained.

[0078] The fluid valve 1 includes a second speed control unit 60 that controls the speed of the valve mechanism 30 when the valve mechanism 30 moves in a direction away from the valve seat 105. Specifically, the second speed control unit 60 includes a rod 602 connected to the piston 302 and a plurality of second spherical members 603 arranged in point contact with a second outer circumferential surface 621 of the rod 602. The second outer circumferential surface 621 of the rod 602 is formed with a third outer circumferential portion 622 and a fourth outer circumferential portion 623 having different diameters, and a second connecting circumferential portion 624 that is an inclined surface connecting to the third outer circumferential portion 622 and the fourth outer circumferential portion 623, and the diameter of the third outer circumferential portion 622 is smaller than the diameter of the fourth outer circumferential portion 623. When the valve mechanism 30 moves in the separating direction, the second spherical member 603 moves relatively from the second connecting peripheral portion 624 to the fourth peripheral portion 623 while in point contact with the second outer peripheral side surface 621, thereby reducing the speed of the valve mechanism 30.

[0079] When transitioning from the closed state to the open state, the valve mechanism 30 starts moving upward at a reduced moving speed, thereby suppressing a sudden increase in the amount of fluid flowing through the flow path 103. As a result, a temporary overshoot-like increase in the amount of fluid flowing through the flow path 103 is suppressed. In other words, it is possible to cause a highly stable fluid to flow out of the outlet 102, with the generation of bubbles, particles, and the like suppressed.

[0080] In the above-described modified example, the second connecting circumferential portion 624 formed on the second outer peripheral side surface 621 of the rod 602 is not limited to a tapered surface formed so that the diameter gradually increases from top to bottom. The second connecting circumferential portion 624 may be formed with a plurality of inclined surfaces with different inclination angles.

[0081] 8(A) and 8(B) are enlarged cross-sectional views showing the vicinity of the second connecting circumferential portion 624 of the rod 602 of the fluid valve 1 in this case. Note that FIG. 8(A) is a cross-sectional view when the fluid valve 1 is in a closed state, and FIG. 8(B) is a cross-sectional view when the fluid valve 1 is in an open state. As shown in FIGS. 8(A) and 8(B), the second connecting circumferential portion 624 is formed with a first inclined surface 624a and a second inclined surface 624b. The first inclined surface 624a is formed above the second inclined surface 624b. The inclination angle of the first inclined surface 624a (angle with respect to a direction perpendicular to the axis X) and the inclination angle of the second inclined surface 624b are different from each other. Specifically, the inclination angle of the first inclined surface 624a formed above is greater than the inclination angle of the second inclined surface 624b formed below. That is, the amount of inclination of the first inclined surface 624a with respect to the axis X is smaller than the amount of inclination of the second inclined surface 624b with respect to the axis X.

[0082] Because the second connecting circumferential portion 624 has the above-described shape, the sliding resistance of the second spherical member 603 against the rod 602 is greater when the second spherical member 603 is in point contact with the second inclined surface 624b than when the second spherical member 603 is in point contact with the first inclined surface 624a. That is, when transitioning from the closed state shown in FIG. 8(A) to the open state shown in FIG. 8(B), the movement speed of the valve mechanism 30 that has started to move upward is regulated. This prevents a sudden increase in the amount of fluid flowing through the flow path 103. That is, it becomes possible to discharge a highly stable fluid with reduced generation of bubbles, particles, and the like.

[0083] Note that, instead of the plurality of inclined surfaces with different inclination angles, a plurality of curved surfaces with different curvatures may be formed on the second connecting circumferential portion 624. Furthermore, the first connecting circumferential portion 406 may also be formed with a plurality of inclined surfaces with different inclination angles or a plurality of curved surfaces with different curvatures.

[0084] Although various embodiments 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.

[0085] In the fluid valve 1 of the above-described embodiment and modified example, the upper surface 412 of the protruding annular portion 410 of the adjusting plate 400, on which the first spherical member 401 is disposed, is not limited to being a plane perpendicular to the axis X as shown in the figure. The upper surface 412 may be a plane inclined with respect to the plane perpendicular to the axis X. For example, the upper surface 412 may be a tapered surface formed so that the distance from the axis X gradually decreases from the upper end to the lower end, and may be an inclined surface inclined at an angle of, for example, approximately 5° to 10° with respect to the plane perpendicular to the axis X. This allows the first spherical member 401 to be more reliably biased against the first outer peripheral side surface 320 of the piston 302.

[0086] 1 fluid valve, 10 flow path block, 20 cylinder portion, 30 valve mechanism, 40 first speed control portion, 50 drive mechanism, 60 second speed control portion, 101 inlet, 102 outlet, 104 valve chamber, 105 valve seat, 204 air port, 301 diaphragm, 302 piston, 320 first outer peripheral side surface, 400 adjustment plate, 401 first spherical member, 402 ball holding portion, 403 elastic member, 404 first outer peripheral portion, 405 second outer peripheral portion, 406 first connecting peripheral portion, 423 inclined surface, 602 rod, 603 second spherical member, 621 second outer peripheral side surface, 622 third outer peripheral portion, 623 fourth outer peripheral portion, 624 second connecting peripheral portion

Claims

a valve mechanism having a diaphragm arranged in the valve chamber so as to be able to come into and move away from the valve seat; and a piston to which the diaphragm is attached and arranged in a cylinder section so as to be able to approach and move away from the valve seat; a drive mechanism which moves the valve mechanism in response to working air supplied or discharged from an airport to control the opening and closing of the valve seat; and a first speed control section which controls the moving speed of the valve mechanism moving in a closing direction to close the valve seat, wherein the first speed control section has: a first outer periphery and a second outer periphery having different diameters formed on a first outer periphery side surface of the piston; a first connecting peripheral portion which is an inclined surface connecting the first outer periphery and the second outer periphery; and a plurality of first ball members arranged in point contact with the first outer periphery side surface of the piston, wherein the diameter of the first outer periphery is larger than the diameter of the second outer periphery, A fluid valve in which the first speed control section slows down the moving speed of the valve mechanism by moving relatively from the second outer periphery through the first connecting peripheral section to the first outer periphery while the first spherical member is in point contact with the first outer periphery side when the valve mechanism moves in the closing direction.

2. A fluid valve as described in claim 1, wherein the first speed control section has a ball holding section which rotatably holds the first ball member while being biased against the first outer peripheral side surface of the piston, and a support section which supports the first ball member from the flow path block side.

3. A fluid valve as described in claim 2, wherein the first speed control section has an elastic member attached to the cylinder section and urging the ball holding section along the closing direction, and the ball holding section faces the first ball member and has a slope that is non-parallel to the closing direction, and urges the first ball member against the first outer peripheral side surface of the piston by making point contact with the first ball member on the slope.

4. A fluid valve as claimed in claim 3, wherein the diaphragm is sandwiched between the support portion and the flow path block.

5. A fluid valve according to claim 4, further comprising a second speed control section for controlling the speed at which the valve mechanism moves in the direction away from the valve seat.

6. A fluid valve as described in claim 5, wherein the second speed control section has a rod connected to the piston and a plurality of second ball members arranged in point contact with the second outer peripheral side surface of the rod, the second outer peripheral side surface of the rod is formed with a third outer peripheral portion and a fourth outer peripheral portion of different diameters and a second connecting peripheral portion which is an inclined surface connecting with the third outer peripheral portion and the fourth outer peripheral portion, the diameter of the third outer peripheral portion is smaller than the diameter of the fourth outer peripheral portion, and the second speed control section reduces the moving speed of the valve mechanism by relatively moving the second ball members from the second connecting peripheral portion to the fourth outer peripheral portion while in point contact with the second outer peripheral side surface of the rod when the valve mechanism moves in the separating direction.

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