JP7627039B2 - Motor-operated valve - Google Patents

Description

The present invention relates to an electrically operated valve operated by a stepping motor.

In recent years, large-scale integration and finer processing have progressed in semiconductor manufacturing, and there are 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 fine debris (particles) in the fluid flow path during the manufacturing process has a significant impact on product yield. In order to maintain yield, it is necessary to keep the size of particles to less than half the wiring pitch and to flow the fluid while maintaining its cleanliness.

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 the flow path connected to a fluid supply source such as a pump. For the flow rate regulating valves arranged in semiconductor manufacturing, motorized valves operated by an electric drive mechanism such as a stepping motor are preferably used. Since motorized valves are operated by electrical control, they have the advantage of allowing a large degree of freedom in maintaining the device and making it easy to control changes in flow rate, etc. However, with general motorized valves, the valve seat can be excessively compressed when the valve body is closed, which can cause problems such as durability issues and particle generation in the motorized valve.

In response to this, an electric valve has been proposed in which a valve mechanism to which a valve body is connected is constantly biased in the closing direction by a spring member, and an operating shaft screwed to the valve mechanism is rotated by an electric drive mechanism to move the valve body forward and backward via the valve mechanism, and when the valve body advances and the valve mechanism advances with the biasing force of the spring member to close the valve seat, the operating shaft is further rotated and retracts (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 body is not pushed into the valve seat, and excessive pressure on the valve seat is avoided, eliminating problems such as particle generation.

When the fluid is cut off in this type of flow path structure, during normal operation the flow control valve (motor valve) closes to cut off the fluid, but if the power is cut off due to a power outage or the emergency stop button is activated, the on-off valve closes to cut off the fluid. With 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.

Publication No. 3227404

This invention was made in consideration of the above points, and provides an electrically operated valve that has a function to avoid excessive pressure when the valve body is closed, as well as a function to cut off fluid when the valve is stopped.

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 to open and close 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 stop member made of a separate member from the valve mechanism and a spring member that constantly urges the stop member toward the valve chamber, the stop member is fitted into the cylinder portion of the working chamber so as to be movable back and forth so as to abut against or separate from the valve mechanism, and when the electric 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, and the valve mechanism is fitted into the working chamber so as to be movable back and forth but not circumferentially rotatable, and the working shaft is inserted into a transmission member of the electric drive mechanism so as to be movable back and forth in the axial direction and rotated, and has a shaft main body having a screw portion which penetrates the stop member and is screwed into the valve mechanism on a tip side thereof, and a locking portion of the stop member formed on the shaft main body and engaged with the locking portion of the stop member and a restricting portion engaged with the stop member to restrict movement of the shaft body in a forward direction, and when the valve mechanism moves backward, the shaft body with the restricting portion engaged with the stop member is axially rotated in one direction by the electric drive mechanism via the transmission member, causing the valve mechanism to move backward via the threaded portion and separate the valve body from the valve seat, and when the valve mechanism moves forward, the shaft body with the restricting portion engaged with the stop member is axially rotated in the other direction by the electric drive mechanism via the transmission member, causing the valve mechanism to move forward via the threaded portion and close the valve body by bringing it close to the valve seat, and when the shaft body is further axially rotated in the other direction, The restricting portion is configured to be separated from the locking portion of the stop member and slide back within the transmission member, and 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 and advancing 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 shaft body slides within the transmission member and is pressed by the stop member to advance the valve mechanism, and the operating shaft advances together with the valve mechanism.

The invention of claim 2 relates to the motor-operated valve of claim 1, in which 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, when the stopping member advances.

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, which biases the valve mechanism in a constantly closing direction with a biasing force smaller than that of the spring member that biases the stop member.

The invention of claim 4 relates to the motor-operated valve according to any one of claims 1 to 3, in which the valve chamber and the valve body are formed of a fluororesin made of PFA or PTFE, a needle valve part made of cross-linked PTFE that opens and closes by abutting against the valve seat of the valve chamber or retracting from the valve seat is joined to the valve body, and an abutment member made of cross-linked PTFE that abuts against the needle valve part when the valve is closed is joined to the valve seat.

The invention of claim 5 relates to the motor-operated valve of claim 4, in which 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.

The invention of claim 6 relates to the motor-operated valve of claim 4 or 5, in which 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.

The invention of claim 7 relates to a method for manufacturing an electric valve according to any one of claims 4 to 6, characterized in that it 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 joined by applying pressure and heating with a heating block that is directly heated by resistance heating, and a valve part joining process in which the needle valve part is placed on the valve body and the needle valve part is joined by applying pressure and heating with the heating block.

The invention of claim 8 relates to the method of manufacturing the motor-operated valve according to claim 7, in which the contact member joining process includes a valve seat side diffusion joining process in which a valve seat side joining member made of PFA is diffusion joined to a valve seat made of PTFE or a contact member made of cross-linked PTFE.

The invention of claim 9 relates to the method of manufacturing the motor-operated valve according to claim 7 or 8, in which the valve portion joining process includes a valve body side diffusion joining process in which a valve body side joining member made of PFA is diffusion joined to a valve body made of PTFE or a needle valve portion made of cross-linked PTFE.

The invention of claim 10 relates to the method for manufacturing the motor-operated valve according to any one of claims 7 to 9, in which 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, the block body made of cross-linked PTFE is heated and pressurized by the heating block to join the block body, 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.

According to 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 at the rear side of the valve chamber, and a drive chamber having an electric drive mechanism arranged at the rear side of the operating chamber are formed, a valve body arranged integrally with a diaphragm in the valve chamber to open and close 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 section that supplies pressurized gas into a cylinder section, and a stop member made of a separate member from the valve mechanism and a spring member that constantly biases the stop member toward the valve chamber are arranged in the cylinder section, and the stop member is a member that is connected to the valve mechanism. and the valve mechanism is fitted into the cylinder portion of the operating chamber so as to be able to advance and retreat so as to abut against or be separated from the body, and when the electric valve is operated, the pressurized gas is supplied to the cylinder portion so as to be constantly urged toward the drive chamber against the urging force of the spring member, and the valve mechanism is fitted into the operating chamber so as to be able to advance and retreat without circumferentially rotating, and the operating shaft is inserted into a transmission member of the electric drive mechanism so as to be able to advance and retreat in the axial direction and is rotated by the operating shaft, and has a shaft main body having a screw portion that penetrates the stop member and is screwed into the valve mechanism at its tip side, and a restricting portion formed on the shaft main body and engaged with an engaging portion of the stop member to restrict movement of the shaft main body in the forward direction, and when the valve mechanism moves backward, the restricting portion engages with the engaging portion of the stop member ... transmitting member. When the valve mechanism advances, the shaft body with the regulating portion engaged with the stop member is axially rotated in one direction via the transmission member by the electric drive mechanism, causing the valve mechanism to retreat via the threaded portion and move the valve body away from the valve seat, and when the valve mechanism advances via the threaded portion and moves the valve body closer 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 slides within the transmission member to retreat, and when the motor-operated valve stops functioning, the supply of pressurized gas is stopped and the valve mechanism advances, causing the valve body to move forward, causing the valve body to move forward, causing the valve body to move forward, The stop 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. When the valve body opens the valve seat, the shaft body slides within the transmission member and is pressed by the stop member to advance the valve mechanism, and the operating shaft advances together with the valve mechanism. This provides a function to avoid excessive pressure when the valve body is closed, as well as a function to cut off fluid when the power is stopped, and can be used alone as a flow control valve and an opening/closing valve for emergency stopping. There is no need to separately place a flow control valve and an opening/closing valve in the piping, which reduces costs and makes the device more compact.

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

According to the motor-operated valve of the invention of claim 3, in the invention of claims 1 or 2, an auxiliary biasing member is provided between the stop member and the valve mechanism body, which biases the valve mechanism body in a constantly closing direction with a biasing force smaller than that of the spring member that biases the stop member, so that the sealing force of the valve body increases when the valve is closed, and the closed state can be more reliably maintained.

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 fluororesin made of PFA or PTFE, a needle valve part made of cross-linked PTFE that opens and closes by abutting against the valve seat of the valve chamber or retracting from the valve seat is joined to the valve body, and a contact member made of cross-linked PTFE that abuts against the needle valve part when the valve is closed is joined to the valve seat, so that the generation of particles when the valve part and the valve seat come into contact can be effectively suppressed.

According to the motor-operated 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.

According to the motor-operated valve of the invention of claim 6, in the invention of claims 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.

According to the manufacturing method of the motor-operated valve according to the invention of claim 7, the manufacturing method of the motor-operated valve according to any one of claims 4 to 6 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 the abutment member, and a valve part joining process in which the needle valve part is placed on the valve body and the needle valve part is heated and pressurized by the heating block to join the needle valve part. Therefore, 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 part made of cross-linked PTFE can be joined with a strong joining strength close to that of a fusion joint that exceeds the strength of a friction joint due to the entanglement of polymers.

According to the motor-operated valve of the invention of claim 8, in the invention of claim 7, the contact member joining process includes a valve seat side diffusion joining process in which a valve seat side joining member made of PFA is diffusion joined to a valve seat made of PTFE or a contact member made of cross-linked PTFE, so that the PTFE valve seat and the cross-linked PTFE contact member can be easily joined.

According to the motor-operated valve of the invention of claim 9, in the invention of claims 7 or 8, the valve portion joining process includes a valve body side diffusion joining process in which a valve body side joining member made of PFA is diffusion joined 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.

According to the motor-operated valve of the invention of claim 10, in the inventions of claims 7 to 9, the valve portion joining process includes a cutting process in which a block body made of cross-linked PTFE is placed on a block body made of PFA or PTFE, 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.

1 is a vertical cross-sectional view of a motor-operated valve according to an embodiment of the present invention when fully open. FIG. FIG. 2 is a vertical cross-sectional view of the motor-operated valve of FIG. 1 when a valve mechanism is moving. FIG. 2 is a vertical cross-sectional view of the motor-operated valve of FIG. 1 when the valve is closed. 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. 2 is a schematic cross-sectional view taken along line AA of FIG. 1. 4 is a schematic exploded perspective view showing the structure of a rear side of the operating shaft and a transmission member of an electric drive mechanism. FIG. 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. 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. 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. 1 is an enlarged cross-sectional view of the vicinity of the valve mechanism during operation of the motor-operated valve and when the power is stopped, with the operating shaft retracted when the valve is closed. FIG. 1 is an enlarged cross-sectional view of the valve mechanism and its vicinity when the power of the motor-operated valve is stopped while the valve mechanism is moving. FIG. 11 is an enlarged cross-sectional view of the vicinity of the front side of the stopping member when it is deactivated. FIG. 13 is an enlarged cross-sectional view showing a structure provided with an auxiliary biasing member in a valve closed state. FIG. FIG. 14 is an enlarged cross-sectional view of the structure of FIG. 13 in a malfunction state. 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. 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. 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. 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. 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. 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. 5A to 5C are schematic cross-sectional views of essential parts illustrating a step of joining a needle valve portion to a valve body. 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.

The motor-operated valve 10 according to one embodiment of the present invention shown in Figures 1 to 4 is a flow control valve that is primarily installed in fluid pipelines in semiconductor manufacturing plants and semiconductor manufacturing equipment, 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.

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. Fluororesins can be easily processed into the desired shape by cutting or other methods. In addition, in this motor-operated valve 10, controlled fluids such as pure water, ammonia water, hydrofluoric acid, hydrogen peroxide, hydrochloric acid, ozone water, hydrogen water, oxygen water, surfactants, and other chemicals, and gases such as hydrogen and oxygen, are circulated.

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 figure, reference numeral 15 denotes a sensor portion disposed on the rear side of the housing for detecting the forward and backward movement of the operating shaft 80, 21 denotes an inlet portion for the controlled fluid connected to one side of the valve chamber 20, and 22 denotes an outlet portion for the controlled fluid connected to the other side of the valve chamber 20 via the valve seat 25.

In the actuation chamber 30, an air supply unit 35 that supplies pressurized gas is provided, and a stop member 40 that is a separate member from the valve mechanism 70 described below and a spring member S that constantly urges the stop member 40 toward the valve chamber 20 are also provided. In the figure, reference numeral 31 denotes a cylinder portion formed in the actuation chamber 30, 32 denotes a valve mechanism holding block that holds the valve mechanism 70 described below in a movable manner on the front side (valve chamber 20 side) of the cylinder portion 31, and 33 denotes the rear end surface of the valve mechanism holding block 32 that corresponds to the front portion of the cylinder portion 31.

The air supply unit 35 is a section that supplies pressurized gas into the cylinder portion 31 of the operating chamber 30, and is connected to a pressure regulating 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 while the motor-operated valve 10 is in operation. The pressurized gas from the air supply unit 35 also acts as a pressurizing means that urges the valve mechanism 70 (described later) in the closing direction when the valve is closed.

The stop member 40 is inserted into the cylinder portion 31 of the operating chamber 30 so as to be movable back and forth so as to abut against or separate from the valve mechanism 70, and is constantly biased toward the drive chamber 50 against the biasing force of the spring member S by the supply of pressurized gas to the operating chamber 30 when the motor-operated valve 10 is in operation. In the figure, reference numeral 41 denotes a front spring bearing portion formed in a concave shape in the stop member 40 and pressed against the spring member S, 42 denotes the front portion of the stop member 40, 45 denotes a locking portion for the operating shaft 80 described below, and 46 denotes a bearing member such as a thrust bearing arranged in the locking portion 45.

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

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 stepping motor, a servo motor, an ultrasonic motor, etc. are preferably used. With regard to the electric drive mechanism 51, 52 is a rotor, 53 is a wiring part, 54 is a front blanket, and 55 is a transmission member that rotates the working shaft 80 described below by the rotor 52. The front blanket 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.

The valve body 60 is a member that is disposed integrally with the diaphragm 65 in the valve chamber 20 and opens and closes the valve seat 25. This valve body 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 operating chamber 30.

The valve mechanism 70 is a member to which the valve body 60 is attached by being inserted coaxially into the working chamber 30 so as to be movable back and forth 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 also has a screw hole 71 in which a helical screw groove is formed at the rear part. In the valve mechanism 70 of the embodiment, a plurality of protrusions 75 are provided at the rear end 72.

The actuating shaft 80 is a member that is connected to the valve mechanism 70 and moves back and forth by the electric drive mechanism 51, and has a shaft body 81 and a restricting portion 85. The shaft body 81 is made of a cylindrical rod-shaped body, passes through the stop member 40, and has a screw portion 82 at its tip that is screwed into the screw hole portion 71 of the valve mechanism 70.

The plate-shaped portion 84 formed at the rear of the shaft body 81 is inserted into the transmission member 55 of the electric drive mechanism 51 so as to be movable in the axial direction, and is rotated by the rotation of the transmission member 55. Here, the transmission member 55 is not particularly limited as long as it has a structure that allows the shaft body 81 to be moved in the axial direction and rotated. As shown in Figures 6 and 7, the transmission member 55 of the embodiment has a through hole 56 having a rectangular cross section into which the plate-shaped portion 84 of the shaft body 81 is slidably inserted, and is made of a substantially cylindrical member that rotates together with the rotor 52 of the electric drive mechanism 51. In the transmission member 55, the through hole 56 having a rectangular cross section and the plate-shaped portion 84 of the shaft body 81 are engaged in the rotation direction, so that the shaft body 81 is rotated through the plate-shaped portion 84 by the axial rotation of the electric drive mechanism 51. In addition, since the through hole 56 and the plate-shaped portion 84 of the shaft body 81 are slidable in the axial direction, the shaft body 81 can be moved forward and backward relative to the transmission member 55. In FIG. 7, the outer peripheral shape of the transmission member 55 is omitted as it is arbitrary.

The rear end of the shaft body 81 is provided with a detectable portion 83 that is detected by a sensor unit 15 arranged on the rear side of the housing 11, and is configured to penetrate the electric drive mechanism 51 and protrude to the rear side of the housing 11 so that the detectable portion 83 can reach the sensor unit 15. The sensor unit 15 arranged on the rear side of the housing 11 can detect the detectable portion 83 of the operating shaft 80 that protrudes to the rear side from the electric drive mechanism 51, making it easier to detect the forward and backward movement of the shaft body 81. In addition, because the sensor unit 15 is arranged using the space behind the electric drive mechanism 51, space saving is achieved, the motorized valve does not need to be large, and the footprint can be made smaller.

The restricting portion 85 is a portion formed on the shaft body 81 and engages with the engaging portion 45 of the stop member 40 to restrict the forward movement of the shaft body 81. In the embodiment, the restricting portion 85 is a disk-shaped member that protrudes from the shaft body 81 and is placed on the engaging portion 45 of the stop member 40 via the bearing member 46.

Next, the normal operation of the motor-operated valve 10 of the present invention will be described. In normal operation, pressurized gas is constantly supplied from the air supply unit 35 to the cylinder portion 31 of the operating 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, that is, toward the front blanket 54 of the electric drive mechanism 51, which corresponds to the rear portion of the cylinder portion 31.

During operation of the motor-operated valve 10, when the valve mechanism 70 shown in Figs. 1 and 8(a) 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 (tightening direction) by the electric drive mechanism 51 via the transmission member 55. 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. Therefore, when the shaft body 81 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 body 60 attached to the valve mechanism 70 is separated from the valve seat 25 to be in an open state. In particular, when the rear part (projection part 75) of the retracted valve mechanism body 70 abuts against the front part 42 of the stop member 40 as shown in the figure, the valve mechanism body 70 retracts to a maximum extent, and the valve seat 25 is fully open.

Next, when the valve mechanism 70 moves forward, as shown in FIG. 2, the shaft body 81 is rotated in the other direction (loosening direction) by the electric drive mechanism 51 via the transmission member 55. 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 moves 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 moves toward the valve chamber 20, and the valve body 60 is brought close to the valve seat 25. Then, as the valve mechanism 70 continues to move forward, the valve body 60 comes into contact with the valve seat 25 and is closed, as shown in FIG. 3 and 9(a).

When the valve body 60 advances and closes as described above, the electric drive mechanism 51 continues to rotate, so the shaft body 81 rotates further in the loosening direction. At this time, the valve body 60 is in contact with the valve seat 25, so the valve mechanism 70 does not advance any further. Meanwhile, since the shaft body 81 can slide axially within the transmission member 55, as shown in Figures 4 and 10(a), the shaft body 81, which rotates axially in the loosening direction, slides back within the transmission member 55 as the restricting portion 85 moves away from the locking portion 45 of the stop member 40.

The fact that the valve mechanism 70 does not move forward after the valve is closed and the operating 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 (it is released as the operating shaft 80 moving backward), so that the valve body 60 is not pushed into the valve seat 25 when the valve is closed, and collisions with the valve seat 25 and excessive friction when the valve is closed are avoided or mitigated. This makes it possible to solve the problems associated with these collisions and friction all at once.

In addition, when the valve is opened after being closed, the actuating shaft 80 is 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, namely, 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 actuating 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 and starting up 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.

Next, the operation of the motor-operated valve 10 of the present invention when it stops functioning will be described. Here, stopping function refers to a state in which the supply of pressurized gas from the air supply unit 35 is stopped in an emergency such as a power outage while the motor-operated valve 10 is in operation or an emergency stop caused by the operation of an emergency stop button (not shown). 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 by stopping the power or the like. Since the operation of the electric drive mechanism 51 is stopped by stopping the power, the operating shaft 80 does not rotate, and the valve mechanism body 70 does not move forward or backward along the operating shaft 80. Note that the procedure for stopping functioning 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.

When the motor-operated valve 10 of the present invention is stopped as described above, 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, pressing the valve mechanism body 70 toward the valve chamber 20 and advancing the valve body 60 to close and hold the valve seat 25 or to maintain the closed state of the valve seat 25 by the valve body 60, and when the valve body 60 opens the valve seat 25, the shaft body 81 slides within the transmission member 55 and advances together with the valve mechanism body 70, which is pressed by the stopping member 40 and advances. Here, the operation of the motor-operated valve 10 when stopped according to the operating state will be described in more detail.

First, when the function of the valve seat 25 shown in Fig. 1 and 8(a) is stopped when it 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 abutted against 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 shaft body 81 of the operating shaft 80 can slide axially within the transmission member 55, it is pressed by the stopping member 40 and moves (advances) toward the valve chamber 20 together with the operating shaft 80.

In this way, when the function is stopped when the valve seat 25 is 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 body 70, so that the valve body 60 is advanced via the valve mechanism body 70 as shown in FIG. 8(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 keeps the valve closed during the function stop.

When the valve seat 25 shown in FIG. 2 is not fully open, that is, when the valve mechanism 70 is moving (forward or backward), the valve mechanism 70 is first separated from the stop member 40 and the movement is stopped at a position where the valve body 60 is not in contact with the valve seat 25. Meanwhile, the stop member 40 is moved toward the valve chamber 20 by the biasing force of the spring member S as shown in FIG. 11(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.

As shown in FIG. 11(b), the valve mechanism 70 pressed against the stop member 40 is advanced in conjunction with the movement of the stop member 40. At that time, the operating shaft 80 connected to the valve mechanism 70 is advanced together with the valve mechanism 70 because the shaft body 81 can slide axially within the transmission member 55. The valve seat 25 is then closed (valve closed) by the valve body 60 that has 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.

When the function is stopped when the valve seat 25 is closed (when the valve is closed) as shown in Figures 3 and 9 (a), the valve mechanism 70 is first stopped at a position where the valve body 60 abuts against the valve seat 25 and closes. Meanwhile, as shown in Figure 9 (b), the stop member 40 is moved toward the valve chamber 20 by the biasing force of the spring member S and abuts against the rear part (projection 75) 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 a 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. 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.

When the valve is closed as shown in Figures 4 and 10(a) and the valve mechanism 70 is stopped at a position where the valve seat 25 is closed by the valve body 60, as in the case of the valve closing. Then, as shown in Figure 10(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 a 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.

When the stopping member 40 advances, as shown in FIG. 12, it is preferable that a gap G is formed between the front surface 42 of the stopping member 40 and the front surface of the cylinder portion 31 (rear end surface 33 of the valve mechanism holding block 32) through which pressurized gas can be introduced from the air supply portion 35. This gap G allows the pressurized gas from the air supply portion 35 to be efficiently introduced between the front surface 42 of the stopping member 40 and the front surface of the cylinder portion 31 when restoring after a malfunction, making it easier for the biasing force of the pressurized gas to act on the front surface 42 of the stopping member 40. This makes it possible to easily and appropriately restore the motor-operated valve 10 after a malfunction.

Figure 12(a) shows a structure in which multiple protrusions 75 are formed on the rear end 72 of the 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. Figure 12(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 of the valve mechanism 70 protrudes into the cylinder portion 31, isolating the front portion 42 of the advanced stop member 40 from the front portion of the cylinder portion 31.

Figure 12(c) shows a structure in which a protrusion 43 is formed on the front surface 42 of the stop member 40, and the protrusion 43 abuts against the rear end 72 of the valve mechanism 70. In this structure, the abutment position between the stop member 40 and the rear end 72 of the valve mechanism 70 is forward of the front surface 42 of the stop member 40, so that even if the rear part 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 part 31 can be isolated.

The structure for forming the gap G on the front side of the cylinder section 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.

As shown and explained 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 stop member 40 toward the drive chamber 50 against the urging force of the spring member S, allowing the valve mechanism 70 to operate normally. When the valve is deactivated, the supply of pressurized gas is stopped, and the urging force of the spring member S causes the stop member 40 to advance, which in turn pressurizes and advances the valve mechanism 70 to close and maintain the valve closed. This allows the fluid to be properly shut off when the valve is deactivated.

In addition, during normal operation, the valve mechanism 70 is configured to move forward without the operating shaft 80 moving backward after the valve is closed, so that 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 control valve and an on-off valve for emergency stop, eliminating the need to place a flow control valve and an on-off valve separately in the piping, which allows for reduced costs and a more compact device.

In addition, the pressurized gas from the air supply unit 35 biases the stop member 40 and 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 open and close the valve body 60 while the motor-operated valve 10 is in operation, and to operate the stop member 40 when it is deactivated, using a single biasing means (pressurized gas).

The motor-operated valve of the present invention is not limited to the above-mentioned embodiment, and can be modified as necessary within the scope of the invention. For example, in the above-mentioned embodiment, the valve mechanism is constantly biased in the closing direction by pressurized gas from the air supply unit. However, as shown in Figs. 13 and 14, an auxiliary biasing member S1 that constantly biases the valve mechanism 70 in the closing direction may be provided between the stop member 40 and the valve mechanism 70. The auxiliary biasing member S1 is a spring member with a smaller biasing force than the spring member S that biases the stop member 40. In the figure, the 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.

When the valve is closed as shown in FIG. 13, the valve mechanism 70 is biased toward the valve chamber 20 (closing direction) by the pressurized gas from the air supply 35 and the auxiliary biasing member S1. This increases the sealing force of the valve body 60, and the valve can be more reliably maintained in the closed state. When the valve is deactivated as shown in FIG. 14, the biasing force of the auxiliary biasing member S1 is smaller than the biasing force of the spring member S, so 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 accommodation portion, so that the stop member 40 can appropriately press the valve mechanism 70. Although not shown, the auxiliary biasing member accommodation portion may be formed on the stop member side.

In addition, 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 from 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 15 to 18 (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.

Cross-linked PTFE is PTFE formed by a cross-linking reaction between molecules, and is produced by an appropriate cross-linking method such as radiation cross-linking. Cross-linked PTFE is more than 1,000 times more abrasion resistant than PTFE, and is less susceptible to deformation due to load, making it highly resistant to aging. In particular, it is more resistant to aging than PTFE at both room temperature and high temperature. Cross-linked PTFE also has the same processability (cutting, welding, pasting, etc.), chemical resistance, non-adhesiveness, electrical properties, corrosion resistance, cleanliness, etc. as PFA and PTFE.

In the example shown in Figures 15 to 18, 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) will be scraped off, and the effect of suppressing particle generation cannot be 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.

The motor-operated valve 10A shown in Figures 15 and 16 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 changes gradually from a position of a diameter less 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.

The motor-operated valve 10B shown in Figures 17 and 18 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 with a small orifice diameter.

Joining of PFA or PTFE to cross-linked PTFE can be performed by pressure and heat bonding. Furthermore, when the valve chamber 20 is made of PTFE, as shown in Figures 15 to 18, it is preferable that the abutment member 26 made of cross-linked PTFE is joined to the valve seat 25 via a valve seat side joining member 90 made of PFA. Similarly, when the valve body 60a is made of PTFE, it is preferable that the needle valve portion 63 made of cross-linked PTFE is joined to the valve body 60a via a valve body side joining member 95 made of PFA.

Here, the abutment member joining process for joining the valve seat 25 and the abutment member 26, and the valve part joining process for joining the valve body 60a and the needle valve part 63 will be specifically described with reference to Figures 19 to 22. Reference numeral 100 in Figure 19 denotes a joining device used in these joining processes, and in Figures 20 to 22, the joining device 100 is illustrated with only the heating block 110, with other parts omitted.

The joining 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 join 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. If necessary, the heating portion 110a of the heating block 110 is coated with DLC (diamond-like carbon) to prevent corrosion by fluorine gas.

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 a pneumatic cylinder or an electric cylinder that is connected to the movable block and lifts and lowers the heating block, 115 denotes a support for the joining device 100, 116 denotes a fixed plate supported by the support, 117 denotes a temperature sensor that detects the temperature of the heating part 110a of the heating block 110, and 118 denotes a displacement sensor that detects the displacement of the movable block 112.

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, which is directly heated by resistance heating, to join 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, which is directly heated by resistance heating, to join the contact member 26.

The example shown in Figure 19 shows an abutment member joining process in which an abutment member 26 made of cross-linked PTFE is joined to a valve seat 25 made of PFA. In this joining process, a cross-linked PTFE abutment member 26 is placed on the valve seat side abutment portion 25a of the PFA valve seat 25, and a 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 cross-linked PTFE abutment member 26 is pressurized and heated to a temperature above the melting point of cross-linked PTFE, and 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. This allows the cross-linked PTFE abutment member 26 and the PFA valve seat 25 to be bonded with a strong bond strength close to that of a fusion bond, which exceeds the strength of a friction bond caused by polymer entanglement.

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. In addition, when machining 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.

20 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 joining 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 joining member 90 made of PFA, and the cross-linked PTFE abutment member 26 is pressurized and heated by a heating block 110 that is directly heated by resistance heating, thereby simultaneously bonding the valve seat 25, the valve seat side joining 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 pressurized and heated from the contact member 26 side, so that 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 are heated by heat transfer 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 joint strength close to that of a molten joint, which exceeds the strength of a friction joint due to polymer entanglement.

Although not shown, in the valve seat side diffusion bonding process, the abutment member 26 and the valve seat side bonding member 90 may be bonded to the valve seat 25 after they are bonded. 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 and the valve seat side bonding member 90. The integrated abutment member 26 and the valve seat side bonding member 90 are then 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.

Furthermore, in the valve seat side diffusion bonding process, the abutment member 26 may be bonded after the valve seat 26 and the valve seat side bonding member 90 are bonded. 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.

In this way, when joining the cross-linked PTFE abutment member 26 to the PTFE valve seat 25, it is preferable to interpose a PFA valve seat side joining member 90 between the two. This is because the melt viscosity of PFA is small compared to the large melt viscosity of PTFE and cross-linked PTFE, 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), the PFA melts in response to the rough joining surface of PTFE or cross-linked PTFE to obtain sufficient joining strength. Therefore, by interposing a PFA valve seat side joining member 90 between the PTFE valve seat 25 and the cross-linked PTFE abutment member 26, the PTFE valve seat 25 and the cross-linked PTFE abutment member 26 can be easily joined.

It is also possible to directly bond a cross-linked PTFE abutment member to the PTFE valve seat. In this case, since it is difficult to obtain sufficient bonding strength if the bonding surfaces of the 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.

The example shown in Figure 21 shows a valve part joining process in which a needle valve part 63 made of cross-linked PTFE is joined to a valve body 60a made of PFA. In this valve part joining process, it is preferable to join a block body B1 made of PFA before molding the valve body 60a and a block body B2 made of cross-linked PTFE before molding the needle valve part 63, and then perform a cutting process in which the block body B1 is formed into the valve body 60a by cutting and the block body B2 is formed into the needle valve part 63 by cutting.

In the valve part joining process shown in FIG. 21, a cross-linked PTFE block B2 that will become the needle valve part 63 is placed on a PFA block B1 that will become the valve body 60a, and the cross-linked PTFE block B2 is pressurized and heated 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 pressurized and heated 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 melts. 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 that of a fusion joint, exceeding the strength of a friction joint due to polymer entanglement.

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, after joining the block body B1 before molding the valve body 60a and the block body B2 before molding the needle valve portion 63, 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.

22 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 block body B2 of cross-linked PTFE that becomes the needle valve portion 63 is placed on a block body B3 of PTFE that becomes the valve body 60a via a valve body side bonding member 95 made of PFA, and the block body B2 of cross-linked PTFE is pressurized and heated by a heating block 110 that is directly heated by resistance heating, and the block body B3 of PTFE, the valve body side bonding member 95 of PFA, and the block body B2 of cross-linked PTFE are simultaneously bonded. At this time, the cross-linked 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 cross-linked PTFE block B2 side, so that they are heated by heat transfer at the contact interface between the cross-linked 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 cross-linked 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 molten joint, which exceeds the strength of a frictional joint due to polymer entanglement.

Although not shown, in the valve body side diffusion bonding process, 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 heating block 110 applies pressure to the block body B2 and heats it, bonding 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 heating block 110 applies pressure to the block body B2 and heats it, bonding the block body B2, the valve body side bonding member 95 and the block body B3.

Furthermore, in the valve body side diffusion bonding process, the PTFE block body B3 and the valve body side bonding member 95 may be bonded, and then the cross-linked PTFE block body B2 may be bonded. 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 heating block 110 pressurizes and heats the block body B2 to bond the block body B2, the valve body side bonding member 95, and the block body B3.

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 allows the needle valve portion 63 to be easily and reliably joined to the valve body 60a via the valve body side joining member 95.

In this way, when joining the cross-linked PTFE needle valve portion 63 to the PTFE valve body 60a, it is preferable to interpose a PFA valve body side joining member 95 between the two. This is because, as in the case of joining the PTFE valve seat 25 and the cross-linked PTFE abutment member 26, 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 PTFE valve body 60a and the cross-linked PTFE needle valve portion 63 can be easily joined by interposing the valve body side joining member 95. It is also possible to directly join the cross-linked PTFE needle valve portion to the PTFE valve body, as in the case of directly joining the cross-linked PTFE abutment member to the PTFE valve seat.

As described above, the motor-operated valve of the present invention has a function to avoid excessive pressure when the valve body is closed, and a function to cut off fluid when the function 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.

10, 10A, 10B Electric valve 11 Housing 15 Sensor section 20 Valve chamber 21 Inflow section 22 Outflow section 25 Valve seat 25a Valve seat side abutment section 26 Abutment member 30 Actuation chamber 31 Cylinder section 32 Valve mechanism body holding block 33 Rear end surface of valve mechanism body holding block 35 Air supply section 40 Stop member 41 Front spring receiving section 42 Front surface of stop member 43 Protruding section of stop member 45 Engagement section 46 Bearing member 50 Drive chamber 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 member of electric drive mechanism 56 Through hole of transmission member 60, 60a Valve body 61 Valve section 62 Sealing section DESCRIPTION OF SYMBOLS 63, 63a, 63b Needle valve portion 64a Taper seal portion 64b Flat seal portion 65 Diaphragm 70 Valve mechanism body 71 Screw hole portion 72 Rear end portion of valve mechanism body 73 Auxiliary biasing member accommodating portion 75 Projection portion 80 Actuating shaft 81 Shaft body 82 Threaded portion 83 Detectable portion 84 Plate-shaped portion 85 Regulating portion 90 Valve seat side joining member 95 Valve body side joining member 100 Joining device 110 Heating block 110a Heating portion of heating block 111 Heater cable 112 Movable block 113 Welding pressure adjustment weight 114 Lifting means 115 Support 116 Fixed plate 117 Temperature sensor 118 Displacement sensor B1, B2, B3 Block body G Gap portion S Spring member S1 Auxiliary biasing member

Claims (10)

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 actuating shaft is axially rotated by being axially inserted through a transmission member of the electric drive mechanism so as to be capable of advancing and retreating in the axial direction, and includes a shaft main body having a screw portion which penetrates the stop member and is screwed into the valve mechanism at a tip end side, and a restricting portion which is formed on the shaft main body and is engaged with a locking portion of the stop member to restrict movement of the shaft main body in a forward direction,
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 restricting 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 close the valve body by bringing it close to the valve seat, and when the shaft body is further axially rotated in the other direction, the restricting portion of the shaft body is separated from the engaging portion of the stop member and slides and retreats within the transmission member,
when the motor-operated valve stops functioning, the supply of pressurized gas is stopped so that 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 and close and hold the valve seat, or maintain the valve seat in a closed state by the valve body, and when the valve body opens the valve seat, the shaft main body slides within the transmission member and is pressed by the stop member to advance the valve mechanism, causing the operating shaft to advance. The motor-operated valve according to claim 1, wherein when the stop member advances, a gap is formed between the front surface of the stop member and the front surface of the cylinder portion, through which pressurized gas can be introduced from the air supply portion. The motor-operated valve according to claim 1 or 2, in which an auxiliary biasing member is provided between the stop member and the valve mechanism, which biases the valve mechanism in a constantly closing direction with a biasing force smaller than that of the spring member that biases the stop member. the valve chamber and the valve body are formed of a fluororesin such as PFA or PTFE,
A needle valve portion made of crosslinked 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. 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. 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. 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;
and a valve portion joining step of placing the needle valve portion on the valve body and heating and pressurizing the needle valve portion by the heating block to join them. The method for manufacturing an electric valve according to claim 7, wherein the contact member joining process includes a valve seat side diffusion joining process in which a valve seat side joining member made of PFA is diffusion joined to a valve seat made of PTFE or a contact member made of cross-linked PTFE. The method for manufacturing an electric valve according to claim 7 or 8, wherein the valve portion joining process includes a valve body side diffusion joining process in which a valve body side joining member made of PFA is diffusion joined to a valve body made of PTFE or a needle valve portion made of cross-linked PTFE. The method for manufacturing an electrically operated valve according to any one of claims 7 to 9, wherein 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, the block body made of cross-linked PTFE is heated and pressurized by the heating block to join the block body, and 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.

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