Motor-operated valve

Abstract

To provide a motor-operated valve having a function to prevent excessive compression and the like in closing a valve element, and also having a fluid cutoff function in function stop.SOLUTION: In backward movement of a valve mechanism body 70, a shaft body 81 of an operation shaft 80 is axially rotated in one direction to retract the valve mechanism body 70 and to separate a valve element 60 from a valve seat 25, in forward movement of the valve mechanism body 70, the shaft body 81 is axially rotated in the other direction to advance the valve mechanism body 70 and to make the valve element 60 approach the valve seat 25 to be closed, and in a case when the shaft body 81 is further axially rotated in the other direction, the operation shaft 80 is retracted to a transmission member 55. In function stop, a stop member 40 is advanced by energization force of a spring member S by supply stop of a pressurized gas, thus the valve mechanism body 70 is pressed and the valve element 60 is advanced to close and hold the valve seat 25 or to keep a valve close state of the valve seat 25, and in valve opening, the operation shaft 80 is pressed by the stop member 40 to the transmission member 55 to advance with the advancing valve mechanism body 70.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motorized valve operated by a stepping motor. [Background technology]

[0002] In recent years, large-scale integration and finer processing have progressed in semiconductor manufacturing, with plans to mass-produce semiconductor devices with a wiring pitch of 3 nm by 2023. In manufacturing semiconductors with such fine wiring widths, the inclusion of minute debris (particles) in the fluid distribution route during the manufacturing process has a significant impact on product yield. To maintain yield, it is necessary to keep the particle size to less than half the wiring pitch and to distribute the fluid while maintaining its cleanliness.

[0003] In this type of flow path structure for semiconductor manufacturing, a pressure regulating valve for adjusting the fluid pressure, a flow rate regulating valve for adjusting the flow rate of the fluid, an on-off valve for blocking or allowing the passage of the fluid, etc. are appropriately arranged in a flow path connected to a fluid supply source such as a pump. As a flow rate regulating valve arranged in semiconductor manufacturing, an electric valve operated by an electric drive mechanism such as a stepping motor is preferably used. Since an electric valve is operated by electrical control, it has the advantage that the degree of freedom in maintaining and managing the device is large and it is easy to control changes in flow rate, etc. However, in a typical electric valve, the valve seat may be excessively compressed when the valve body is closed, which may cause problems such as durability of the electric valve and generation of particles.

[0004] In view of this, an electric valve has been proposed in which a valve mechanism to which a valve disc is connected is constantly biased in the closing direction by a spring member, an operating shaft screwed to the valve mechanism is rotated by an electric drive mechanism to advance and retract the valve disc via the valve mechanism, and when the valve mechanism is advanced together with the biasing force of the spring member to close the valve seat when the valve disc advances, the operating shaft is further rotated to cause the operating shaft to retract (see Patent Document 1). In this electric valve, the operating shaft retracts after the valve seat is closed (valve closed), so that the operation by the electric drive mechanism after the valve is closed is not transmitted to the valve mechanism, and the valve disc is not pushed into the valve seat, and excessive pressure on the valve seat is avoided, thereby eliminating problems such as the generation of particles.

[0005] In this type of flow path structure, when the fluid is cut off, the flow control valve (motor valve) closes during normal operation, but if the power is cut off due to a power outage or the emergency stop button is operated, the on-off valve closes to cut off the fluid. In conventional flow path structures, in addition to the flow control valve, an on-off valve for emergency stop must be separately placed in the piping, which causes problems such as increased costs and larger equipment, and improvements are required. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Publication No. 3227404 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned points, and provides an electrically operated valve that has a function of avoiding excessive pressure, etc. when the valve body is closed, as well as a function of cutting off fluid when the valve body stops functioning. [Means for solving the problem]

[0008] That is, the invention of claim 1 is an electric valve including a housing in which a valve chamber in which a valve seat is formed, an operating chamber arranged on the rear side of the valve chamber, and a drive chamber having an electric drive mechanism arranged on the rear side of the operating chamber, a valve body arranged integrally with a diaphragm in the valve chamber for opening and closing the valve seat, a valve mechanism to which the valve body is attached, and an operating shaft connected to the valve mechanism and moved forward and backward by the electric drive mechanism, and the operating chamber is provided with an air supply unit that supplies pressurized gas into a cylinder portion, and a stopper formed of a member separate from the valve mechanism. A stop member and a spring member that constantly biases the stop member toward the valve chamber are disposed in the cylinder portion, the stop member is fitted into the cylinder portion of the operating chamber so as to be movable back and forth so as to abut against or separate from the valve mechanism, and when the motor-operated valve is operated, the stop member is constantly biased and held toward the drive chamber against the biasing force of the spring member by the supply of pressurized gas to the cylinder portion, the valve mechanism is fitted into the operating chamber so as to be freely movable back and forth but not rotatable in the circumferential direction, and the operating shaft passes through the stop member and has a screw portion at its tip end that is screwed into the valve mechanism. a transmission engagement portion formed on a rear end side of the shaft body and circumferentially engaging with a transmission member of the electric drive mechanism; and a restriction portion formed on the shaft body and engaged with a locking portion of the stop member to restrict movement of the shaft body in an forward direction, the shaft body being advanceable and retreatable relative to the transmission member and being axially rotated via the transmission member which rotates axially by operation of the electric drive mechanism, and during retreat of the valve mechanism, the shaft body with the restriction portion engaged with the stop member is axially rotated in one direction by the electric drive mechanism via the transmission member, thereby rotating the valve mechanism in the forward direction. When the valve mechanism moves forward, the shaft body with the regulating portion engaged with the stop member is axially rotated in the other direction via the transmission member by the electric drive mechanism, so that the valve mechanism moves forward via the screw portion to bring the valve body close to the valve seat and close it, and when the shaft body is further axially rotated in the other direction, the regulating portion of the shaft body is separated from the engaging portion of the stop member and the operating shaft is retracted relative to the transmission member, and when the motor-operated valve stops functioning,The motor-operated valve is configured such that, when the supply of the pressurized gas is stopped, the stop member is moved toward the valve chamber by the biasing force of the spring member, and presses the valve mechanism body toward the valve chamber to advance the valve body, thereby closing and holding the valve seat, or holding the valve seat in a closed state by the valve body, and when the valve body opens the valve seat, the operating shaft advances together with the valve mechanism body, which is advanced by being pressed by the stop member, relative to the transmission member.

[0009] The invention of claim 2 relates to the electric valve of claim 1, in which, when the stopping member advances, a gap is formed between the front surface of the stopping member and the front surface of the cylinder portion, through which pressurized gas can be introduced from the air supply portion.

[0010] The invention of claim 3 relates to the motor-operated valve of claim 1 or 2, in which an auxiliary biasing member is provided between the stop member and the valve mechanism body, the auxiliary biasing member biasing the valve mechanism body in a constantly closing direction with a biasing force smaller than that of the spring member biasing the stop member.

[0011] The invention of claim 4 relates to the motor-operated valve according to any one of claims 1 to 3, wherein the valve chamber and the valve body are formed from a fluororesin made of PFA or PTFE, a needle valve portion made of cross-linked PTFE that abuts against the valve seat of the valve chamber or retracts from the valve seat to open and close is joined to the valve body, and an abutment member made of cross-linked PTFE that abuts against the needle valve portion when the valve is closed is joined to the valve seat.

[0012] The invention of claim 5 relates to the motor-operated valve according to claim 4, wherein the valve chamber is made of PTFE, and the abutment member is joined to the valve seat via a valve seat side joining member made of PFA.

[0013] The invention of claim 6 relates to the motor-operated valve according to claim 4 or 5, wherein the valve body is made of PTFE, and the needle valve portion is joined to the valve seat via a valve body side joining member made of PFA.

[0014] The invention of claim 7 relates to a method for manufacturing an electrically operated valve as defined in any one of claims 4 to 6, comprising an abutment member joining process in which the abutment member is placed on the valve seat of the valve chamber and the abutment member is heated and pressurized by a heating block that is directly heated by resistance heating to join the abutment member, and a valve portion joining process in which the needle valve portion is placed on the valve body and the needle valve portion is heated and pressurized by the heating block to join the needle valve portion.

[0015] The invention of claim 8 relates to a manufacturing method for an electric valve as described in claim 7, wherein the abutment member joining process includes a valve seat side diffusion joining process for diffusion joining a valve seat side joining member made of PFA to a valve seat made of PTFE or an abutment member made of cross-linked PTFE.

[0016] The invention of claim 9 relates to a method for manufacturing an electric valve as described in claim 7 or 8, wherein the valve portion joining process includes a valve body side diffusion joining process for diffusion joining a valve body side joining member made of PFA to a valve body made of PTFE or a needle valve portion made of cross-linked PTFE.

[0017] The invention of claim 10 relates to the method for manufacturing the motor-operated valve according to any one of claims 7 to 9, wherein the valve portion joining step includes a cutting step of placing a block body made of cross-linked PTFE on a block body made of PFA or PTFE, heating the block body made of cross-linked PTFE under pressure by the heating block to join them, and then forming the block body made of PFA or PTFE into a valve body by cutting, and forming the block body made of cross-linked PTFE into a needle valve portion by cutting. Effect of the Invention

[0018] According to the motor-operated valve of the invention of claim 1, the motor-operated valve includes a housing in which a valve chamber in which a valve seat is formed, an operating chamber arranged on the rear side of the valve chamber, and a drive chamber having an electric drive mechanism arranged on the rear side of the operating chamber, a valve body arranged integrally with a diaphragm in the valve chamber for opening and closing the valve seat, a valve mechanism to which the valve body is attached, and an operating shaft connected to the valve mechanism and moved forward and backward by the electric drive mechanism, and the operating chamber is provided with an air supply unit that supplies pressurized gas into a cylinder portion, and a valve mechanism separate from the valve mechanism. a stop member configured as a stop member and a spring member for constantly biasing the stop member toward the valve chamber are disposed in the cylinder portion, the stop member is inserted into the cylinder portion of the operating chamber so as to be movable forward and backward so as to abut against or separate from the valve mechanism, and when the motor-operated valve is operated, the stop member is constantly biased and held toward the drive chamber side against the biasing force of the spring member by the supply of the pressurized gas to the cylinder portion, the valve mechanism is inserted into the operating chamber so as to be freely movable forward and backward but not rotatable in the circumferential direction, and the operating shaft is formed with a screw portion at its tip end which penetrates the stop member and is screwed into the valve mechanism. a transmission engagement portion formed on a rear end side of the shaft body and circumferentially engaging with a transmission member of the electric drive mechanism; and a restriction portion formed on the shaft body and engaged with a locking portion of the stop member to restrict movement of the shaft body in an forward direction, the shaft body being advanceable and retreatable relative to the transmission member and being axially rotated via the transmission member which rotates axially by operation of the electric drive mechanism, and during retreat of the valve mechanism, the shaft body with the restriction portion engaged with the stop member is axially rotated in one direction by the electric drive mechanism via the transmission member to rotate the screw. When the valve mechanism moves forward, the shaft body with the regulating portion engaged with the stop member is axially rotated in the other direction via the transmission member by the electric drive mechanism, so that the valve mechanism moves forward via the screw portion to bring the valve body close to the valve seat and close it, and when the shaft body is further axially rotated in the other direction, the regulating portion of the shaft body is separated from the engaging portion of the stop member and the operating shaft is retracted relative to the transmission member, and when the motor-operated valve stops functioning,When the supply of the pressurized gas is stopped, the stopping member is moved toward the valve chamber by the biasing force of the spring member, and presses the valve mechanism toward the valve chamber to advance the valve body to close and hold the valve seat, or holds the valve seat in a closed state by the valve body, and when the valve body opens the valve seat, the operating shaft advances together with the valve mechanism which is advanced by being pressed by the stopping member against the transmission member. Therefore, with the function of avoiding excessive compression when the valve body is closed and the function of cutting off fluid when the power is stopped, the valve can be used independently as a flow control valve and an on-off valve for emergency stop, and there is no need to separately arrange a flow control valve and an on-off valve in the piping, which allows for cost reduction and miniaturization of the device.

[0019] According to the electric valve of the invention of claim 2, in the invention of claim 1, when the stopping member advances, a gap portion through which pressurized gas can be introduced from the air supply portion is formed between the front portion of the stopping member and the front portion of the cylinder portion, making it possible to easily and appropriately restore the electric valve after it stops functioning.

[0020] According to the electric valve of the invention of claim 3, in the invention of claim 1 or 2, an auxiliary biasing member is provided between the stopping member and the valve mechanism body, which biases the valve mechanism body in the constantly closing direction with a biasing force smaller than that of the spring member which biases the stopping member, so that the sealing force of the valve body is increased when the valve is closed, making it possible to more reliably maintain the closed state.

[0021] According to the motor-operated valve of the invention of claim 4, in the inventions of claims 1 to 3, the valve chamber and the valve body are formed of a fluororesin made of PFA or PTFE, a needle valve portion made of cross-linked PTFE that abuts against the valve seat of the valve chamber or retracts from the valve seat to open and close is joined to the valve body, and an abutment member made of cross-linked PTFE that abuts against the needle valve portion when the valve is closed is joined to the valve seat, thereby effectively suppressing the generation of particles when the valve portion and the valve seat come into contact with each other.

[0022] According to the electric valve of the invention of claim 5, in the invention of claim 4, the valve chamber is made of PTFE, and the abutment member is joined to the valve seat via a valve seat side joining member made of PFA, so that the abutment member made of cross-linked PTFE can be easily joined to the valve seat made of PTFE.

[0023] According to the electric valve of the invention of claim 6, in the invention of claim 4 or 5, the valve body is made of PTFE, and the needle valve portion is joined to the valve seat via a valve body side joining member made of PFA, so that the needle valve portion made of cross-linked PTFE can be easily joined to the valve body made of PTFE.

[0024] According to the manufacturing method of the motor-operated valve of the invention of claim 7, there is provided a manufacturing method of the motor-operated valve as defined in any one of claims 4 to 6, which includes an abutment member joining process in which the abutment member is placed on the valve seat of the valve chamber and the abutment member is heated and pressurized by a heating block that is directly heated by resistance heating to join it, and a valve portion joining process in which the needle valve portion is placed on the valve body and the needle valve portion is heated and pressurized by the heating block to join it, so that the valve seat made of PFA or PTFE and the abutment member made of cross-linked PTFE, and the valve body made of PFA or PTFE and the needle valve portion made of cross-linked PTFE can be joined with a strong joining strength close to that of fusion joining, which exceeds the strength of friction joining due to polymer entanglement.

[0025] According to the electric valve of the invention of claim 8, in the invention of claim 7, the abutment member joining process includes a valve seat side diffusion joining process of diffusion joining a valve seat side joining member made of PFA to a valve seat made of PTFE or an abutment member made of cross-linked PTFE, so that the PTFE valve seat and the cross-linked PTFE abutment member can be easily joined.

[0026] According to the motor-operated valve of the invention of claim 9, in the invention of claim 7 or 8, the valve portion joining process includes a valve body side diffusion joining process of diffusion joining a valve body side joining member made of PFA to a valve body made of PTFE or a needle valve portion made of cross-linked PTFE, so that the PTFE valve body and the cross-linked PTFE needle valve portion can be easily joined.

[0027] According to the motor-operated valve of the invention of claim 10, in the inventions of claims 7 to 9, the valve portion joining step includes a cutting step in which a block body made of cross-linked PTFE is placed on a block body made of PFA or PTFE, and the block body made of cross-linked PTFE is heated and pressurized by the heating block to join them, and then the block body made of PFA or PTFE is formed into a valve body by cutting, and the block body made of cross-linked PTFE is formed into a needle valve portion by cutting, so that the needle valve portion can be easily and reliably joined to the valve body. [Brief description of the drawings]

[0028] [Figure 1] 1 is a vertical cross-sectional view of a motor-operated valve according to an embodiment of the present invention when fully open. FIG. [Diagram 2] 2 is a vertical cross-sectional view of the motor-operated valve of FIG. 1 when a valve mechanism is moving. FIG. [Diagram 3] FIG. 2 is a vertical sectional view of the motor-operated valve of FIG. 1 when the valve is closed. [Figure 4] 2 is a vertical cross-sectional view of the motor-operated valve of FIG. 1 in a state where the operating shaft is retracted when the valve is closed. [Diagram 5] 2 is a schematic cross-sectional view taken along the line AA in FIG. 1. [Figure 6] 4 is a schematic cross-sectional view showing the structure of a rear side of an operating shaft and a transmission member of an electric drive mechanism. FIG. [Figure 7] 1 is an enlarged cross-sectional view of the valve mechanism and its vicinity when the motor-operated valve is fully open and when it is not functioning. FIG. [Figure 8] 4 is an enlarged cross-sectional view of the valve mechanism and its vicinity during operation and when the motor-operated valve is stopped when the valve is closed. FIG. [Figure 9]1 is an enlarged cross-sectional view of the vicinity of the valve mechanism during operation and during non-operation of the motor-operated valve with the operating shaft retracted when the valve is closed. FIG. [Figure 10] FIG. 11 is an enlarged cross-sectional view of the vicinity of the valve mechanism when the valve mechanism stops functioning during movement. [Figure 11] 11 is an enlarged cross-sectional view of the vicinity of the front side of the stopping member when it is deactivated. FIG. [Figure 12] 13 is an enlarged cross-sectional view showing a structure provided with an auxiliary biasing member in a valve closed state. FIG. [Figure 13] FIG. 13 is an enlarged cross-sectional view of the structure of FIG. 12 in a malfunction state. [Figure 14] 4 is an enlarged cross-sectional view of a valve chamber of a motor-operated valve having a needle valve portion formed with a tapered seal portion when fully open. FIG. [Figure 15] 4 is an enlarged cross-sectional view of a valve chamber of a motor-operated valve having a needle valve portion formed with a tapered seal portion when the valve is closed. FIG. [Figure 16] 4 is an enlarged cross-sectional view of a valve chamber of a motor-operated valve having a needle valve portion in which a flat seal portion is formed, when the motor-operated valve is fully open. FIG. [Figure 17] 4 is an enlarged cross-sectional view of a valve chamber of a motor-operated valve having a needle valve portion formed with a flat seal portion when the valve is closed. FIG. [Figure 18] 5 is a schematic cross-sectional view of a main portion illustrating a process of joining an abutment member to a valve seat by a joining device. FIG. [Figure 19] 10 is a schematic cross-sectional view of a main portion illustrating a step of joining an abutment member to a valve seat via a valve seat side joining member. FIG. [Figure 20] 5A to 5C are schematic cross-sectional views of essential parts illustrating a step of joining a needle valve portion to a valve body. [Figure 21] 5 is a schematic cross-sectional view of a main portion illustrating a step of joining a needle valve portion to a valve body via a valve body side joining member. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] 1 to 4, a motor-operated valve 10 according to one embodiment of the present invention is a flow control valve that is mainly installed in fluid pipelines in semiconductor manufacturing plants, semiconductor manufacturing equipment, etc., and is configured to adjust and cut off the flow rate of a fluid. This motor-operated valve 10 includes a housing 11, a valve body 60, a valve mechanism 70, and an operating shaft 80.

[0030] In the motor-operated valve 10, each part that comes into contact with the fluid, such as the housing 11 and the valve body 60, is made of a material that is highly resistant to corrosion and chemicals. For example, fluororesins such as PTFE, PFA, and PVDF are used. Fluororesins can be easily processed into a desired shape by cutting or the like. In addition, in this motor-operated valve 10, controlled fluids such as pure water, ammonia water, hydrofluoric acid, hydrogen peroxide water, hydrochloric acid, ozone water, hydrogen water, oxygen water, surfactants, and other chemicals, and gases such as hydrogen and oxygen, are circulated.

[0031] The housing 11 is formed with a valve chamber 20 in which a valve seat 25 is formed, an operating chamber 30 disposed on the rear side of the valve chamber 20, and a drive chamber 50 having an electric drive mechanism 51 disposed on the rear side of the operating chamber 30. In the drawing, reference numeral 21 denotes an inlet portion for the controlled fluid connected to one side of the valve chamber 20, and reference numeral 22 denotes an outlet portion for the controlled fluid connected to the other side of the valve chamber 20 via the valve seat 25.

[0032] The actuation chamber 30 is provided with an air supply unit 35 for supplying pressurized gas, as well as a stop member 40 formed as a separate member from a valve mechanism 70 (described later), and a spring member S for constantly urging the stop member 40 toward the valve chamber 20. In the figure, reference numeral 31 denotes a cylinder portion formed within the actuation chamber 30, 32 denotes a valve mechanism holding block that holds the valve mechanism 70 (described later) on the front side (valve chamber 20 side) of the cylinder portion 31 so that the valve mechanism 70 can advance and retreat, and 33 denotes a rear end face of the valve mechanism holding block 32 that corresponds to the front portion of the cylinder portion 31.

[0033] The air supply unit 35 is a portion that supplies pressurized gas into the cylinder portion 31 of the operating chamber 30, and is connected to a pressure adjusting device (not shown) such as a known electropneumatic regulator. In this air supply unit 35, a pressurized gas supply hole 36 is formed on the front side of the cylinder portion 31 (the rear end surface 33 side of the valve mechanism holding block 32), and pressurized gas is constantly supplied during operation of the motor-operated valve 10. The pressurized gas from the air supply unit 35 also acts as a pressurizing means that urges a valve mechanism 70 (described later) in the closing direction when the valve is closed.

[0034] The stop member 40 is fitted into the cylinder portion 31 of the operating chamber 30 so as to be able to advance and retreat so as to come into contact with or be separated from the valve mechanism 70, and when the motor-operated valve 10 is operated, the stop member 40 is constantly urged toward the drive chamber 50 against the urging force of the spring member S by the supply of pressurized gas to the operating chamber 30. In the drawing, reference numeral 41 denotes a front spring bearing portion formed in a concave shape in the stop member 40 and pressed by the spring member S, 42 denotes a front portion of the stop member 40, 45 denotes a locking portion for the operating shaft 80 described later, and 46 denotes a bearing member such as a thrust bearing arranged in the locking portion 45.

[0035] The spring member S is an elastic member that is disposed between the stopping member 40 and an electric drive mechanism 51 described below, and constantly urges the stopping member 40 toward the valve chamber 20. The spring member S is not particularly limited as long as it is an elastic member that urges the stopping member 40, but a known coil spring that has a simple configuration and is inexpensive is preferable.

[0036] The electric drive mechanism 51 is a member that adjusts the amount of advance and retreat under the control of an appropriate computing device (not shown) to advance and retreat the working shaft 80 described below. The electric drive mechanism 51 is not particularly limited as long as it can accurately reproduce the amount of advance and retreat of the working shaft 80, and for example, a known rotary motor such as a stepping motor, a servo motor, or an ultrasonic motor is preferably used. Regarding the electric drive mechanism 51, 52 is a rotor, 53 is a wiring part, 54 is a front bracket, 55 is a transmission member that rotates about its axis by the rotor 52, 56 is a rotating body of the transmission member 55, and 57 is a rod-shaped body of the transmission member 55 formed by protruding from the rotating body 56 to the front side (the working chamber 30 side). The front bracket 54 of the electric drive mechanism 51 is the rear surface part of the cylinder part 31 of the working chamber 30 and corresponds to the rear spring bearing part of the spring member S.

[0037] The valve element 60 is a member disposed integrally with a diaphragm 65 in the valve chamber 20 to open and close the valve seat 25. The valve element 60 has a valve portion 61 that moves forward and backward to seat on the valve seat 25 or retract from the valve seat 25 to open and close the valve seat 25. The shape of the valve portion 61 is not particularly limited as long as it can reliably open and close the valve seat 25. The illustrated valve portion 61 has a flat-shaped seal portion 62. The diaphragm 65 is made of a thin movable membrane and prevents the controlled fluid flowing through the valve chamber 20 from entering the working chamber 30.

[0038] The valve mechanism 70 is a member to which the valve element 60 is attached by being inserted coaxially into the working chamber 30 so as to be able to freely advance and retreat without being rotatable in the circumferential direction. As shown in Fig. 5, the valve mechanism 70 is inserted into the valve mechanism holding block 32 of the working chamber 30 by a known spline fitting structure. The valve mechanism 70 has a screw hole 71 in which a helical screw groove is formed in the rear part. In the valve mechanism 70 of the embodiment, a plurality of protrusions 75 are provided at the rear end 72.

[0039] The operating shaft 80 is a member that is connected to the valve mechanism 70 and is moved forward and backward by the electric drive mechanism 51, and has a shaft body 81, a transmission engagement portion 83, and a regulating portion 85. The shaft body 81 is made of a cylindrical rod-shaped body, and is formed with a threaded portion 82 that penetrates the stop member 40 and is screwed into the threaded hole portion 71 of the valve mechanism 70 on the tip side. In addition, the transmission engagement portion 83 is a portion that is formed on the rear end side of the shaft body 81 and engages with the rod-shaped body 57 of the transmission member 55 of the electric drive mechanism 51 in the circumferential direction.

[0040] 6, the transmission engagement portion 83 at the rear end of the shaft body 81 of the working shaft 80 is engaged with the rod-shaped body 57 of the transmission member 55 in the circumferential direction, and therefore, when the transmission member 55 rotates axially, rotational motion is transmitted from the rod-shaped body 57 via the transmission engagement portion 83, causing the working shaft 80 to rotate axially. The working shaft 80 is configured to be movable forward and backward relative to the transmission member 55 while maintaining the engagement of the transmission engagement portion 83 with the rod-shaped body 57 of the transmission member 55.

[0041] In the transmission engagement portion 83 formed in the shaft body 81, a movement space portion 84 is formed in front of the tip surface of the rod-shaped body 57 of the engaging transmission member 55. The movement space portion 84 is a portion for preventing the tip surface of the rod-shaped body 57 from contacting the shaft body 81 when the operating shaft 80 retracts, thereby preventing the retraction of the operating shaft 80. The length (depth) of the movement space portion 84 is not particularly limited as long as it is possible to prevent contact with the tip surface of the rod-shaped body 57, and it may be, for example, a non-through hole of a predetermined length as shown in Figures 1 to 4, or a through hole not shown.

[0042] The shape of the transmission engagement portion 83 may be any suitable structure that engages with the rod-shaped body 57 of the transmission member 55 in the circumferential direction to allow the operating shaft 80 to advance and retreat. In this embodiment, as shown in Fig. 6, the rod-shaped body 57 of the transmission member 55 has a generally rectangular cross section, and the transmission engagement portion 83 is formed on the rear end side of the shaft main body 81 as a non-through hole having a generally rectangular cross section corresponding to the shape of the rod-shaped body 57. Note that the cross-sectional shapes of the rod-shaped body 57 and the transmission engagement portion 83 may be polygonal, such as generally pentagonal or hexagonal, in addition to the generally rectangular shape shown in the figure.

[0043] Restriction portion 85 is a portion formed on shaft body 81 and engaged with locking portion 45 of stopping member 40 to restrict forward movement of shaft body 81. In the embodiment, restriction portion 85 is a disk-shaped member protruding from the rear of shaft body 81, and is placed on locking portion 45 of stopping member 40 via bearing member 46.

[0044] Next, a description will be given of the normal operation of the motor-operated valve 10 of the present invention. In normal operation, pressurized gas is constantly supplied from the air supply unit 35 into the cylinder unit 31 of the working chamber 30, and the stop member 40 is constantly biased and held against the biasing force of the spring member S toward the drive chamber 50, i.e., toward the front bracket 54 of the electric drive mechanism 51 corresponding to the rear portion of the cylinder unit 31.

[0045] 1 and 7(a) during the operation of the motor-operated valve 10, when the valve mechanism 70 moves backward, that is, when the valve is opened (when the valve seat 25 is open), the shaft body 81 is first rotated in one direction (the tightening direction) via the transmission member 55 which is rotated in one direction by the electric drive mechanism 51. At this time, the restricting portion 85 of the operating shaft 80 is placed on the locking portion 45 of the stop member 40 via the bearing member 46, and the movement of the operating shaft 80 in the forward direction is restricted. Thus, when the operating shaft 80 rotates in the tightening direction, the rotational motion is transmitted to the valve mechanism 70 via the screw portion 82, and the valve mechanism 70 moves in the backward direction along the operating shaft 80. Therefore, the valve mechanism 70 moves toward the drive chamber 50, and the valve element 60 attached to the valve mechanism 70 is separated from the valve seat 25 to be in the open state. In particular, when the rear portion (projection portion 75) of the retracted valve mechanism 70 abuts against the front portion 42 of the stop member 40 as shown in the figure, the valve mechanism 70 retracts to a maximum extent and the valve seat 25 is fully opened.

[0046] Subsequently, when the valve mechanism 70 moves forward, as shown in Fig. 2, the shaft body 81 is axially rotated in the other direction (loosening direction) via the transmission member 55, which is axially rotated in the other direction by the electric drive mechanism 51. As the shaft body 81 rotates in the loosening direction, the rotational motion is transmitted to the valve mechanism 70 via the screw portion 82, and the valve mechanism 70 is moved forward along the operating shaft 80 together with the biasing force of the pressurized gas from the air supply unit 35. Therefore, the valve mechanism 70 is separated from the stop member 40 and moved toward the valve chamber 20, and the valve element 60 is brought close to the valve seat 25. Then, as the valve mechanism 70 continues to move forward, the valve element 60 comes into contact with the valve seat 25 and is in a closed state, as shown in Figs. 3 and 8(a).

[0047] When the valve element 60 advances and closes as described above, the electric drive mechanism 51 continues to rotate, so that the shaft body 81 further rotates in the loosening direction. At this time, the valve element 60 is in contact with the valve seat 25, so that the valve mechanism body 70 does not advance any further. On the other hand, the working shaft 80 can advance and retreat with respect to the transmission member 55, so that as shown in Figs. 4 and 9(a), the working shaft 80, which rotates in the loosening direction, retreats while maintaining the engagement between the transmission engagement portion 83 and the rod-shaped body 57 of the transmission member 55, with the regulating portion 85 separated from the locking portion 45 of the stop member 40. At this time, a movement space portion 84 is formed in front of the tip surface of the rod-shaped body 57 of the transmission member 55 that engages with the transmission engagement portion 83, so that the working shaft 80 smoothly retreats without being hindered by the rod-shaped body 57.

[0048] The fact that the valve mechanism 70 does not move forward after the valve is closed and the working shaft 80 itself moves backward means that the rotational motion from the electric drive mechanism 51 after the valve is closed is not transmitted to the valve mechanism 70 (is released as the backward motion of the working shaft 80), so that the valve element 60 is not pushed into the valve seat 25 when the valve is closed, and collision with the valve seat 25 and excessive friction when the valve is closed are avoided or mitigated. Therefore, the occurrence of problems associated with these collisions and friction can be solved in one fell swoop.

[0049] In addition, when the valve is opened after being closed, the operating shaft 80 is in a state of being loosened and retreated from the valve mechanism body 70 more than usual, so there is no need to maintain the excitation of the motor to maintain the force to fully close the valve body 60 against the valve seat 25 or the pushing force such as the fully closed sealing force of the valve seat 25. Therefore, it is possible to solve all the problems associated with this, that is, not only the problem of current consumption but also various problems related to the temperature rise of the controlled fluid due to the heat generated by the motor. Furthermore, since the movement in the valve opening direction, that is, the rotational movement of the operating shaft 80 in the tightening direction can be started from a state without load, it is possible to perform ramp control such as valve opening control at a small flow rate or starting from zero flow rate. In addition, in the motor-operated valve 10 of the present invention, when the stepping motor of the electric drive mechanism 51 is driven by the microstep drive method, the forward and backward movement of the valve body 60 can be controlled more precisely to finely adjust the opening degree of the valve seat 25.

[0050] Next, the operation of the motor-operated valve 10 of the present invention when the function stops will be described. Here, the function stop refers to a state in which the supply of pressurized gas from the air supply unit 35 is stopped in an emergency such as power stop due to a power outage or emergency stop due to operation of an emergency stop button (not shown) while the motor-operated valve 10 is in operation. In the motor-operated valve 10 of the embodiment, when an emergency occurs, the supply of pressurized gas is stopped first, and then the power of the motor-operated valve 10 is stopped due to a power outage or the like. Since the operation of the electric drive mechanism 51 is stopped due to the power stop, the operating shaft 80 does not rotate, and the valve mechanism body 70 does not advance or retreat along the operating shaft 80. Note that the procedure for stopping the function is not limited to this, and it is sufficient that the supply of pressurized gas is stopped and the operation of the electric drive mechanism 51 is stopped in an emergency.

[0051] The motor-operated valve 10 of the present invention is configured such that, when the motor-operated valve 10 is stopped as described above, the supply of pressurized gas from the air supply unit 35 is stopped, causing the stopping member 40 to move towards the valve chamber 20 by the urging force of the spring member S, pressing the valve mechanism body 70 towards the valve chamber 20 and moving the valve element 60 forward to close and hold the valve seat 25 or to hold the valve seat 25 in a closed state by the valve element 60, and when the valve element 60 opens the valve seat 25, the operating shaft 80 is pressed by the stopping member 40 and moves forward relative to the transmission member 55 together with the valve mechanism body 70. Here, the operation of the motor-operated valve 10 when stopped according to the operating state will be described in more detail.

[0052] 1 and 7(a), when the function is stopped while the valve seat 25 is fully open, the supply of pressurized gas from the air supply unit 35 is stopped, and the stopping member 40 is moved toward the valve chamber 20 by the biasing force of the spring member S. At this time, since the rear part (projection part 75) of the valve mechanism body 70 is in contact with the front side of the stopping member 40, the stopping member 40 presses the valve mechanism body 70 toward the valve chamber 20 as it moves (advances) toward the valve chamber 20. Here, the valve mechanism body 70 is connected to the operating shaft 80 whose operation has been stopped, but since the operating shaft 80 can advance and retreat while maintaining the engagement between the transmission engagement part 83 and the rod-shaped body 57 of the transmission member 55, the valve mechanism body 70 is moved (advances) toward the valve chamber 20 together with the operating shaft 80 by being pressed by the stopping member 40.

[0053] In this way, when the valve seat 25 is stopped while fully open, the stop member 40, which moves forward due to the biasing force of the spring member S, presses and advances the valve mechanism 70, so that the valve body 60 is advanced via the valve mechanism 70 as shown in Fig. 7(b), and the valve seat 25 is closed (the valve is closed). And, since the stop member 40 is constantly biased toward the valve chamber 20 by the spring member S, the biasing force of the spring member S maintains the valve closed state during this function stop.

[0054] When the valve seat 25 shown in Fig. 2 is not fully open, that is, when the valve mechanism 70 is moving (advancing or retreating), the valve mechanism 70 is first separated from the stop member 40 and its movement is stopped at a position where the valve element 60 is not in contact with the valve seat 25. Meanwhile, the stop member 40 is moved toward the valve chamber 20 by the urging force of the spring member S, as shown in Fig. 10(a). At this time, since the operating shaft 80 is stopped together with the valve mechanism 70, the engagement portion 45 of the stop member 40 is separated from the restriction portion 85. Then, when the advancing stop member 40 comes into contact with the rear end portion 72 of the stopped valve mechanism 70, the valve mechanism 70 is pressed toward the valve chamber 20 as it advances.

[0055] The valve mechanism 70 pressed by the stop member 40 is advanced in association with the movement of the stop member 40, as shown in Fig. 10(b). At that time, the operating shaft 80 connected to the valve mechanism 70 is advanced and retreated while maintaining the engagement between the transmission engagement portion 83 and the rod-shaped body 57 of the transmission member 55, and is advanced together with the valve mechanism 70. Then, the valve seat 25 is closed (the valve is closed) by the valve element 60 advanced via the valve mechanism 70, and the closed state is maintained by the biasing force of the spring member S during the said function stop.

[0056] When the function is stopped when the valve seat 25 is closed (when the valve is closed) as shown in Figures 3 and 8(a), the valve mechanism 70 is first stopped at a position where the valve element 60 abuts against the valve seat 25 and closes. Meanwhile, the stop member 40 is moved toward the valve chamber 20 by the urging force of the spring member S and abuts against the rear part (projection 75) of the valve mechanism 70, as shown in Figure 8(b). As a result, the valve mechanism 70 is pressed and held at a position where the valve seat 25 is closed by the stop member 40 urged by the spring member S, and the valve closed state is maintained by the urging force of the spring member S during the function stop. Note that since the operating shaft 80 is stopped together with the valve mechanism 70 which is stopped at the closed position of the valve seat 25, the operating shaft 80 does not move and only the stop member 40 is advanced.

[0057] 4 and 9(a), when the function is stopped when the operating shaft 80 moves backward after the valve is closed, the valve mechanism 70 is first stopped at a position where the valve seat 25 is closed by the valve element 60, similar to the valve closing time. Then, as shown in Fig. 9(b), the stop member 40 is also moved toward the valve chamber 20 by the biasing force of the spring member S, and abuts against the rear end surface 33 of the valve mechanism holding block 32 together with the rear end 72 of the valve mechanism 70. As a result, the valve mechanism 70 is pressed and held by the stop member 40 biased by the spring member S at the position where the valve seat 25 is closed, and the valve closed state is maintained by the biasing force of the spring member S during the function stop.

[0058] 11, it is preferable that a gap G into which pressurized gas can be introduced from the air supply unit 35 is formed between the front surface 42 of the stopping member 40 and the front surface of the cylinder unit 31 (rear end surface 33 of the valve mechanism holding block 32). This gap G allows the pressurized gas from the air supply unit 35 to be efficiently introduced between the front surface 42 of the stopping member 40 and the front surface of the cylinder unit 31 when restoring after a malfunction, and the biasing force of the pressurized gas can easily act on the front surface 42 of the stopping member 40. Therefore, it is possible to easily and appropriately restore the motor-operated valve 10 after a malfunction.

[0059] Fig. 11(a) shows a structure in which a plurality of protrusions 75 are formed on a rear end 72 of a valve mechanism 70, and when the valve is closed, the protrusions 75 protrude from the rear end surface 33 of the valve mechanism holding block 32 into the cylinder portion 31. Fig. 11(b) shows a structure in which when the valve is closed, the rear end 72 of the valve mechanism 70 protrudes from the rear end surface 33 of the valve mechanism holding block 32 into the cylinder portion 31. In these structures, the rear part of the valve mechanism 70 protrudes into the cylinder portion 31, isolating the front part 42 of the advanced stop member 40 from the front part of the cylinder portion 31.

[0060] 11(c) shows a structure in which a protrusion 43 is formed on a front surface 42 of the stop member 40, and the protrusion 43 abuts against a rear end portion 72 of the valve mechanism 70. In this structure, the abutment position between the stop member 40 and the rear end portion 72 of the valve mechanism 70 is forward of the front surface 42 of the stop member 40, so that even if the rear portion of the valve mechanism 70 is forward of the rear end surface 33 of the valve mechanism holding block 32 when the valve is closed, the front surface 42 of the stop member 40 and the front surface of the cylinder portion 31 can be separated.

[0061] The structure for forming the gap G on the front side of the cylinder portion 31 when the stop member 40 advances is not limited to the above example, and can be configured as appropriate, for example, by providing a protrusion on the stop member side or on both the stop member and the valve mechanism body.

[0062] As shown and described above, in the motor-operated valve 10 of the present invention, when in operation, the supply of pressurized gas from the air supply unit 35 constantly urges the stopping member 40 toward the drive chamber 50 against the urging force of the spring member S, allowing the valve mechanism 70 to operate normally, and when the valve mechanism 70 stops functioning, the supply of pressurized gas is stopped, causing the stopping member 40 to advance due to the urging force of the spring member S, and as the stopping member 40 moves, the valve mechanism 70 is pressed forward to close and maintain the valve closed. Therefore, the fluid can be appropriately shut off when the valve mechanism 70 stops functioning.

[0063] Furthermore, in normal operation, since the valve mechanism 70 is configured to move forward without the operating shaft 80 moving backward after the valve is closed, the rotational motion from the electric drive mechanism 51 is not transmitted to the valve mechanism 70 after the valve is closed, and excessive compression when the valve is closed can be appropriately avoided. Therefore, the motor-operated valve 10 of the present invention can function independently as a flow rate control valve and an on-off valve for emergency stop, eliminating the need to separately place a flow rate control valve and an on-off valve in the piping, thereby reducing costs and making the device more compact.

[0064] Furthermore, the pressurized gas from the air supply unit 35 not only biases and holds the stopping member 40, but also biases the valve mechanism 70 in the closing direction when the valve is closed. At this time, the rear end face of the valve mechanism 70 becomes the pressure-receiving surface for the pressurized gas. This makes it possible to appropriately perform the opening and closing operations of the valve element 60 while the motor-operated valve 10 is in operation, and the operation of the stopping member 40 when the motor-operated valve 10 is deactivated, using a single biasing means (pressurized gas).

[0065] The motor-operated valve of the present invention is not limited to the above-mentioned embodiment, and may be modified as appropriate within the scope of the invention. For example, in the above-mentioned embodiment, the valve mechanism is normally biased in the closing direction by pressurized gas from the air supply unit. However, as shown in Figs. 12 and 13, an auxiliary biasing member S1 may be provided between the stop member 40 and the valve mechanism 70 to normally bias the valve mechanism 70 in the closing direction. The auxiliary biasing member S1 is a spring member having a smaller biasing force than the spring member S that biases the stop member 40. In the figures, reference numeral 73 denotes an auxiliary biasing member housing portion formed in the rear end portion 72 of the valve mechanism 70 so that the auxiliary biasing member S1 can be housed therein.

[0066] In the valve-closed state shown in FIG. 12, the valve mechanism 70 that has moved forward is biased toward the valve chamber 20 (closing direction) by the pressurized gas from the air supply unit 35 and the auxiliary biasing member S1. This increases the sealing force of the valve body 60, and the valve-closed state can be more reliably maintained. In addition, in the non-functioning state shown in FIG. 13, the biasing force of the auxiliary biasing member S1 is smaller than the biasing force of the spring member S, so that the stop member 40 is advanced by the biasing force of the spring member S without being hindered by the auxiliary biasing member S1. At that time, the auxiliary biasing member S1 is pressed by the stop member 40 and accommodated in the auxiliary biasing member accommodating portion, so that the stop member 40 can appropriately press the valve mechanism 70. Although not shown, the auxiliary biasing member accommodating portion may be formed on the stop member side.

[0067] In the motor-operated valve of the present invention, each part such as the housing and valve body is made of an appropriate fluororesin. For example, the valve chamber and valve body may be formed of a fluororesin made of PFA or PTFE, and a needle valve portion 63 made of cross-linked PTFE that abuts against the valve seat 25 or retracts from the valve seat 25 to open and close may be joined to the valve body 60a, as in the motor-operated valves 10A and 10B shown in Figures 14 to 17 (each figure is an enlarged cross-sectional view of the valve chamber), and an abutment member 26 made of cross-linked PTFE that abuts against the needle valve portion 63 when the valve is closed may be joined to the valve seat 25.

[0068] Crosslinked PTFE is PTFE formed by crosslinking reaction between molecules, and is prepared by an appropriate crosslinking method such as radiation crosslinking. Crosslinked PTFE has abrasion resistance 1000 times or more than PTFE, and is resistant to deformation due to load and has excellent resistance to denaturation. In particular, it has better resistance to denaturation than PTFE at both room temperature and high temperature. In addition, crosslinked PTFE has the same processability such as cutting, welding, and pasting, chemical resistance, non-adhesiveness, electrical properties, corrosion resistance, cleanliness, etc. as PFA and PTFE.

[0069] In the examples shown in Figures 14 to 17, the contact member 26 of the valve seat 25 and the needle valve portion 63, which come into contact with each other, are made of cross-linked PTFE, which has excellent abrasion resistance. In fields that require high cleanliness, such as semiconductor manufacturing, even if one of the valve portion or the valve seat (contact member) is made of cross-linked PTFE, the other fluororesin (PTFE or PFA) is scraped off, and the effect of suppressing particle generation is not sufficiently obtained. Therefore, by making both the contact member 26 of the valve seat 25 and the needle valve portion 63 out of cross-linked PTFE, it is possible to effectively suppress the generation of particles when the valve portion and the valve seat (contact member) come into contact with each other.

[0070] 14 and 15, the motor-operated valve 10A has a needle valve portion 63a in which the orifice diameter of the outflow portion 22 is formed to be large, and a tapered seal portion 64a is formed to abut against the abutment member 26 of the valve seat 25. In the needle valve portion 63a of the illustrated embodiment, the tapered seal portion 64a is formed so that the inclination angle gradually changes from a position of a diameter smaller than the orifice diameter of the outflow portion 22. In addition, the abutment member 26 is formed in an annular shape corresponding to the outflow portion 22 having a large orifice diameter.

[0071] 16 and 17, the motor-operated valve 10B has a needle valve portion 63b in which the orifice diameter of the outflow portion 22 is small, and a flat seal portion 64b is formed to abut against the abutment member 26 of the valve seat 25. In the needle valve portion 63b of the illustrated embodiment, the flat seal portion 64b is formed at a position with approximately the same diameter as the orifice diameter of the outflow portion 22, and abuts against the upper surface side of the abutment member 26 when the valve is closed. In addition, the abutment member 26 is formed in an annular shape corresponding to the outflow portion 22 having a small orifice diameter.

[0072] The joining of PFA or PTFE to cross-linked PTFE can be performed by pressure and heat joining. When the valve chamber 20 is made of PTFE, the abutment member 26 made of cross-linked PTFE is preferably joined to the valve seat 25 via a valve seat side joining member 90 made of PFA, as shown in Figures 14 to 17. Similarly, when the valve body 60a is made of PTFE, the needle valve portion 63 made of cross-linked PTFE is preferably joined to the valve body 60a via a valve body side joining member 95 made of PFA.

[0073] Here, the contact member joining process for joining the valve seat 25 and the contact member 26, and the valve portion joining process for joining the valve body 60a and the needle valve portion 63 will be specifically described with reference to Figures 18 to 21. Reference numeral 100 shown in Figure 18 denotes a joining device used in these joining processes, and in Figures 19 to 21, the joining device 100 is illustrated with only a heating block 110, with other components omitted.

[0074] The bonding device 100 has a heating block 110 that applies pressure to and directly heats the contact member 26, the needle valve portion 63, etc., to bond them to the valve seat 25 and the valve body 60a. The heating block 110 has a heating element such as a nichrome wire, and heats by resistance heating, which generates heat when power is supplied from a heater cable 111. The surface of the heating portion 110a of the heating block 110 is preferably smooth, and in this embodiment, the surface roughness (arithmetic mean roughness: Ra) is 0.03 μm. The heating portion 110a of the heating block 110 is coated with DLC (diamond-like carbon) to prevent corrosion by fluorine gas, as necessary.

[0075] In the figure, reference numeral 112 denotes a movable block to which the heating block 110 is attached, 113 denotes a weight for adjusting the welding pressure to apply a predetermined load when pressure is applied by the heating block 110, 114 denotes a lifting means such as an air cylinder or an electric cylinder connected to the movable block to raise and lower the heating block, 115 denotes a support pillar of the joining device 100, 116 denotes a fixed plate supported by the support pillar, 117 denotes a temperature sensor for detecting the temperature of the heating part 110a of the heating block 110, and 118 denotes a displacement sensor for detecting displacement of the movable block 112.

[0076] In the contact member joining process, the contact member 26 is placed on the valve seat 25 of the valve chamber 20, and the contact member 26 is pressurized and heated by the heating block 110 that is directly heated by resistance heating, thereby joining the contact member 26. In the valve portion joining process, the needle valve portion 63 is placed on the valve body 60a, and the needle valve portion 63 is pressurized and heated by the heating block 110 that is directly heated by resistance heating, thereby joining the contact member 26.

[0077] The example shown in FIG. 18 shows an abutment member joining process for joining an abutment member 26 made of cross-linked PTFE to a valve seat 25 made of PFA. In this joining process, the abutment member 26 made of cross-linked PTFE is placed on the valve seat side abutment portion 25a of the PFA valve seat 25, and the heating block 110 is abutted against the abutment member 26. At this time, a load is applied to the heating block 110 by the welding pressure adjustment weight 113, so that the abutment member 26 made of cross-linked PTFE is heated at a temperature equal to or higher than the melting point of cross-linked PTFE while being pressurized, and is softened or semi-melted. By being pressurized and heated from the abutment member 26 side, the PFA valve seat 25 is heated by heat transfer at the contact interface with the abutment member 26 and melted. As a result, the abutment member 26 made of cross-linked PTFE and the PFA valve seat 25 are joined with a strong joining strength close to fusion joining that exceeds the strength of friction joining due to polymer entanglement.

[0078] The abutment member 26 to be joined to the valve seat 25 can be processed appropriately, for example, by machining the abutment member 26 into an annular shape by cutting before joining to the valve seat 25, or by machining the abutment member 26 into an annular shape by cutting after joining to the valve seat 25 as a circular member. When machining the abutment member 26 after joining, it is also possible to join the abutment member 26 to the valve seat 25 before the orifice of the outflow portion 22 is formed, and machine the abutment member 26 into an annular shape at the same time as the orifice is formed.

[0079] 19 shows an example of an abutment member joining process for joining an abutment member 26 made of cross-linked PTFE to a valve seat 25 made of PTFE, and includes a valve seat side diffusion bonding process for diffusion bonding a valve seat side bonding member 90 made of PFA to the valve seat 25 or the abutment member 26. In the illustrated valve seat side diffusion bonding process, the abutment member 26 is placed on the valve seat side abutment portion 25a of the valve seat 25 via the valve seat side bonding member 90 made of PFA, and the abutment member 26 of cross-linked PTFE is heated while being pressurized by a heating block 110 which is directly heated by resistance heating, thereby simultaneously bonding the valve seat 25, the valve seat side bonding member 90, and the abutment member 26. At this time, the contact member 26 is softened or semi-melted by the heat, and the valve seat side joining member 90 made of PFA and the valve seat side contact portion 25a of the valve seat 25 made of PTFE are heated and pressurized from the contact member 26 side, so that they are heated by heat transfer at the contact interface between the contact member 26 and the valve seat side joining member 90 and the contact interface between the valve seat side joining member 90 and the valve seat side contact portion 25a, and melted. As a result, the contact member 26 of crosslinked PTFE, the valve seat side joining member 90 of PFA, and the valve seat 25 of PTFE are joined with a strong joining strength close to that of a fusion joint, which exceeds the strength of a friction joint due to polymer entanglement.

[0080] Furthermore, although not shown, in the valve seat side diffusion bonding step, the abutment member 26 and the valve seat side bonding member 90 may be bonded to the valve seat 25 after they are bonded to each other. When bonding the abutment member 26 and the valve seat side bonding member 90, the abutment member 26 is placed on the valve seat side bonding member 90, and the abutment member 26 is heated and pressurized by the heating block 110 to bond the abutment member 26 to the valve seat side bonding member 90. Then, the integrated abutment member 26 and the valve seat side bonding member 90 are placed on the valve seat 25, and the abutment member 26 is heated and pressurized by the heating block 110 to bond the abutment member 26, the valve seat side bonding member 90, and the valve seat 25.

[0081] Furthermore, in the valve seat side diffusion bonding step, the abutment member 26 may be bonded after bonding the valve seat 26 and the valve seat side bonding member 90. When bonding the valve seat 25 and the valve seat side bonding member 90, the valve seat side bonding member 90 is placed on the valve seat side abutment portion 25a of the valve seat 25, and the valve seat side bonding member 90 is pressurized and heated by the heating block 110 to bond the valve seat side bonding member 90 and the valve seat 25. Then, the abutment member 26 is placed on the valve seat side bonding member 90 bonded to the valve seat 25, and the abutment member 26 is pressurized and heated by the heating block 110 to bond the abutment member 26, the valve seat side bonding member 90, and the valve seat 25.

[0082] In this way, when the abutment member 26 of cross-linked PTFE is joined to the valve seat 25 of PTFE, it is preferable to interpose the valve seat side joining member 90 of PFA between them. This is because the melt viscosity of PFA is small while that of PTFE and cross-linked PTFE is large, so that even if the joining surface of PTFE or cross-linked PTFE is relatively rough (for example, arithmetic mean roughness: Ra is 0.4 μm), PFA melts in correspondence with the rough joining surface of PTFE or cross-linked PTFE, and sufficient joining strength is obtained. Therefore, by interposing the valve seat side joining member 90 of PFA between the valve seat 25 of PTFE and the abutment member 26 of cross-linked PTFE, the valve seat 25 of PTFE and the abutment member 26 of cross-linked PTFE can be easily joined.

[0083] It is also possible to directly bond a contact member made of cross-linked PTFE to a valve seat made of PTFE. In this case, since it is difficult to obtain sufficient bonding strength if the bonding surfaces of PTFE or cross-linked PTFE are rough, it is preferable to set the arithmetic mean roughness (Ra) of the bonding surfaces to less than 0.1 μm. This allows the PTFE, which has a high melt viscosity, and the cross-linked PTFE to be bonded appropriately.

[0084] 20 shows a valve portion joining step of joining a needle valve portion 63 made of cross-linked PTFE to a valve body 60a made of PFA. In this valve portion joining step, it is preferable to join a block body B1 made of PFA before molding the valve body 60a to a block body B2 made of cross-linked PTFE before molding the needle valve portion 63, and then form the block body B1 into the valve body 60a by cutting, and to perform a cutting step of forming the block body B2 into the needle valve portion 63 by cutting.

[0085] In the valve portion joining process shown in Fig. 20, a cross-linked PTFE block B2 that will become the needle valve portion 63 is placed on a PFA block B1 that will become the valve body 60a, and the cross-linked PTFE block B2 is heated and pressurized by a heating block 110 that is directly heated by resistance heating. At this time, the cross-linked PTFE block B2 is softened or semi-melted by the heat, and the PFA block B1 is heated and pressurized from the cross-linked PTFE block B2 side, so that it is heated by heat transfer at the contact interface with the cross-linked PTFE block B2 and melted. As a result, the PFA block B1 and the cross-linked PTFE block B2 are joined with a strong joining strength that is close to a fusion joining strength that exceeds the strength of friction joining due to polymer entanglement.

[0086] After joining the PFA block body B1 and the cross-linked PTFE block body B2, the block body B1 is cut by cutting to form the valve body 60a, and the block body B2 is cut by cutting to form the needle valve portion 63. In this way, the block body B1 before the valve body 60a is molded and the block body B2 before the needle valve portion 63 is molded are joined, and then the block body B1 is formed into the valve body 60a and the block body B2 is formed into the needle valve portion 63 by a cutting process, so that the needle valve portion 63 can be easily and reliably joined to the valve body 60a.

[0087] 21 shows a process of joining a needle valve portion 63 made of cross-linked PTFE to a valve body 60a made of PTFE, and includes a valve body side diffusion bonding process of diffusion bonding a valve body side bonding member 95 made of PFA to the valve body 60a made of PTFE or the needle valve portion 63 made of cross-linked PTFE. In the illustrated valve body side diffusion bonding process, a cross-linked PTFE block body B2 which becomes the needle valve portion 63 is placed on a PTFE block body B3 which becomes the valve body 60a via a valve body side bonding member 95 made of PFA, and the cross-linked PTFE block body B2 is pressurized and heated by a heating block 110 which is directly heated by resistance heating, thereby simultaneously bonding the PTFE block body B3, the PFA valve body side bonding member 95, and the cross-linked PTFE block body B2. At this time, the crosslinked PTFE block B2 is softened or semi-melted by the heat, and the PFA valve body side joining member 95 and the PTFE valve body 60a are pressurized and heated from the crosslinked PTFE block B2 side, so that they are heated by heat transfer at the contact interface between the crosslinked PTFE block B2 and the valve body side joining member 95 and at the contact interface between the valve body side joining member 95 and the PTFE block B3, and melted. As a result, the crosslinked PTFE block B2, the PFA valve body side joining member 95, and the PTFE block B3 are joined with a strong joining strength close to that of a fusion joint, which exceeds the strength of a friction joint due to polymer entanglement.

[0088] Although not shown, in the valve body side diffusion bonding step, the crosslinked PTFE block body B2 and the valve body side bonding member 95 may be bonded to the PTFE block body B3 after bonding them together. When bonding the block body B2 and the valve body side bonding member 95, the block body B2 is placed on the valve body side bonding member 95, and the block body B2 is pressurized and heated by the heating block 110 to bond the valve body side bonding member 95 and the block body B2. The integrated block body B2 and the valve body side bonding member 95 are then placed on the block body B3, and the block body B2 is pressurized and heated by the heating block 110 to bond the block body B2, the valve body side bonding member 95, and the block body B3.

[0089] Furthermore, in the valve body side diffusion bonding step, the cross-linked PTFE block body B2 may be bonded after bonding the PTFE block body B3 and the valve body side bonding member 95. When bonding the block body B3 and the valve body side bonding member 95, the valve body side bonding member 95 is placed on the block body B3, and the valve seat side bonding member 90 is pressurized and heated by the heating block 110 to bond the valve body side bonding member 95 and the block body B3. Then, the cross-linked PTFE block body B2 is placed on the valve body side bonding member 95 bonded to the block body B3, and the block body B2 is pressurized and heated by the heating block 110 to bond the block body B2, the valve body side bonding member 95, and the block body B3.

[0090] After the PTFE block body B3 and the cross-linked PTFE block body B2 are joined via the valve body side joining member 95, the block body B3 is cut by cutting to form the valve body 60a, and the block body B2 and the valve body side joining member 95 are cut by cutting to form the needle valve portion 63 with the valve body side joining member 95 interposed therebetween. This makes it possible to easily and reliably join the needle valve portion 63 to the valve body 60a via the valve body side joining member 95.

[0091] In this way, when the needle valve portion 63 of cross-linked PTFE is joined to the valve body 60a of PTFE, it is preferable to interpose the valve body side joining member 95 of PFA between them. This is because, as in the case of joining the valve seat 25 of PTFE and the abutment member 26 of cross-linked PTFE, sufficient joining strength can be obtained by interposing PFA even when the joining surface of PTFE or cross-linked PTFE is relatively rough (for example, arithmetic mean roughness: Ra is 0.4 μm). Therefore, the valve body 60a of PTFE and the needle valve portion 63 of cross-linked PTFE can be easily joined by interposing the valve body side joining member 95. It is also possible to directly join the needle valve portion of cross-linked PTFE to the valve body of PTFE, as in the case of directly joining the abutment member of cross-linked PTFE to the valve seat of PTFE. [Industrial Applicability]

[0092] As described above, the motor-operated valve of the present invention has a function to prevent excessive pressure when the valve body is closed, and a function to cut off the fluid when the valve is stopped, and can function independently as both a flow control valve and an on-off valve for emergency stop. Therefore, it is promising as a replacement for motor-operated valves used in semiconductor manufacturing, etc. [Explanation of symbols]

[0093] 10, 10A, 10B Motor-operated valve 11. Housing 20 Valve chamber 21 Inlet 22 Outflow section 25 Valve seat 25a Valve seat side contact part 26 Contact member 30 Working chamber 31 Cylinder section 32 Valve mechanism retaining block 33 Rear end face of valve mechanism retaining block 35 Air supply section 40 Stop member 41 Front spring support 42 Front part of stop member 43 Stop member protrusion 45 Locking part 46 Bearing parts 50 Drive Room 51 Electric drive mechanism 52 Rotor of electric drive mechanism 53 Wiring section of electric drive mechanism 54 Front bracket of electric drive mechanism 55 Transmission components of electric drive mechanism 56 Rotating body of transmission member 57 Rod-shaped body of transmission member 60 Valve body 61 Valve section 62 Seal part 63, 63a, 63b Needle valve section 64a Taper seal part 64b Flat seal part 65 Diaphragm 70 Valve mechanism 71 Screw hole 72 Rear end of valve mechanism 73 Auxiliary biasing member housing 75 Protrusion 80 Working shaft 81 Shaft body 82 Screw Attachment 83 Transmission engagement part 84 Moving space 85 Regulatory Department 90 Valve seat side joint member 95 Valve body side joint member 100 Joining equipment 110 Heating Block 110a Heating part of heating block 111 Heating cable 112 Movable Block 113 Welding pressure adjustment weight 114 Lifting means 115 Post 116 Fixing plate 117 Temperature Sensor 118 Displacement Sensor B1, B2, B3 block letters G Gap S Spring material S1 Auxiliary biasing member

Claims

1. a housing in which a valve chamber in which a valve seat is formed, an operating chamber disposed on the rear side of the valve chamber, and a drive chamber having an electric drive mechanism disposed on the rear side of the operating chamber are formed; a valve body disposed integrally with a diaphragm in the valve chamber for opening and closing the valve seat; a valve mechanism to which the valve body is attached; an operating shaft connected to the valve mechanism and moved forward and backward by the electric drive mechanism; A motor-operated valve comprising: an air supply unit that supplies pressurized gas into the cylinder portion is provided in the actuation chamber, and a stop member that is a separate member from the valve mechanism and a spring member that constantly biases the stop member toward the valve chamber are disposed in the cylinder portion, the stop member is inserted into the cylinder portion of the operating chamber so as to be movable back and forth so as to abut against or be separated from the valve mechanism, and when the motor-operated valve is operated, the stop member is constantly biased toward the drive chamber against the biasing force of the spring member by the supply of the pressurized gas to the cylinder portion, The valve mechanism is inserted into the working chamber so as to be movable back and forth but not rotatable in a circumferential direction, The operating shaft has a shaft main body having a screw portion formed at its tip side which penetrates the stop member and is screwed into the valve mechanism, a transmission engagement portion formed at the rear end side of the shaft main body and which circumferentially engages with a transmission member of the electric drive mechanism, and a regulating portion formed on the shaft main body and engaged with a locking portion of the stop member to regulate forward movement of the shaft main body, and is configured to be able to advance and retreat relative to the transmission member and to be axially rotated via the transmission member which rotates axially by operation of the electric drive mechanism, When the valve mechanism moves backward, the shaft main body, with the regulating portion engaged with the stop member, is axially rotated in one direction by the electric drive mechanism via the transmission member, so that the valve mechanism is moved backward via the threaded portion to separate the valve body from the valve seat, When the valve mechanism moves forward, the shaft body, with the regulating portion engaged with the stop member, is axially rotated in the other direction via the transmission member by the electric drive mechanism to advance the valve mechanism via the threaded portion and bring the valve body close to the valve seat to close it, and when the shaft body is further axially rotated in the other direction, the regulating portion of the shaft body is separated from the engaging portion of the stop member and the operating shaft is retracted relative to the transmission member, When the motor-operated valve stops functioning, the supply of the pressurized gas is stopped, and the stop member is moved toward the valve chamber by the biasing force of the spring member, pressing the valve mechanism toward the valve chamber to advance the valve body to close and hold the valve seat, or to hold the valve seat in a closed state by the valve body, and when the valve body opens the valve seat, the operating shaft is pressed by the stop member and advances relative to the transmission member together with the valve mechanism which advances. A motor-operated valve.

2. 2. The motor-operated valve according to claim 1, wherein when the stopping member advances, a gap is formed between a front surface of the stopping member and a front surface of the cylinder portion, through which pressurized gas can be introduced from the air supply portion.

3. 3. The motor-operated valve according to claim 1, further comprising an auxiliary biasing member provided between the stop member and the valve mechanism for biasing the valve mechanism in a constantly closing direction with a biasing force smaller than that of the spring member for biasing the stop member.

4. the valve chamber and the valve body are formed of a fluororesin such as PFA or PTFE, A needle valve portion made of cross-linked PTFE is joined to the valve body and opens and closes by contacting with the valve seat of the valve chamber or retracting from the valve seat.

4. The motor-operated valve according to claim 1, wherein an abutment member made of cross-linked PTFE is joined to the valve seat and abuts against the needle valve portion when the valve is closed.

5. 5. The motor-operated valve according to claim 4, wherein the valve chamber is made of PTFE, and the contact member is joined to the valve seat via a valve seat side joining member made of PFA.

6. 6. The motor-operated valve according to claim 4, wherein the valve body is made of PTFE, and the needle valve portion is joined to the valve seat via a valve body side joining member made of PFA.

7. A method for manufacturing the motor-operated valve according to any one of claims 4 to 6, comprising the steps of: a contact member joining step of placing the contact member on the valve seat of the valve chamber and joining the contact member by applying pressure and heat using a heating block that is directly heated by resistance heating; a valve portion joining step of placing the needle valve portion on the valve body and joining the needle valve portion by applying pressure and heat with the heating block. A method for manufacturing a motor-operated valve.

8. The method for manufacturing an electrically operated valve according to claim 7, wherein the contact member joining step includes a valve seat side diffusion joining step of diffusion joining a valve seat side joining member made of PFA to a valve seat made of PTFE or a contact member made of cross-linked PTFE.

9. The method for manufacturing an electrically operated valve according to claim 7 or 8, wherein the valve portion joining step includes a valve body side diffusion joining step of diffusion joining a valve body side joining member made of PFA to a valve body made of PTFE or a needle valve portion made of cross-linked PTFE.

10. 10. The method for manufacturing an electrically operated valve according to claim 7, further comprising the steps of: placing a block body made of cross-linked PTFE on a block body made of PFA or PTFE; heating and pressurizing the block body made of cross-linked PTFE by the heating block to bond the block body; and then forming the block body made of PFA or PTFE into a valve body by cutting; and forming the block body made of cross-linked PTFE into a needle valve portion by cutting.

Images