Electric valve

Abstract

To provide an electric valve in which a stopper arranged at a magnet rotor can be eliminated, and which can stop the rotation of the magnet rotor when the movement of a valve body is stopped.SOLUTION: An electric valve 1 has a valve main body 10, a valve body 40, a valve shaft 34, a stepping motor 66 and a control device 80. A male screw 34c is formed at the valve shaft 34, and a female screw 13c is formed at the valve main body 10. The valve shaft 34 is fixed to a magnet rotor 31, and a lower end of the valve shaft 34 is connected to the valve body 40. When the magnet rotor 31 rotates in a valve closing direction, the valve body 40 moves toward a valve port 15. When the valve body 40 is connected to a valve seat 16, the movement of the valve body 40 toward the valve port 15 is regulated. The control device 80 detects that the rotation of the magnet rotor 31 in the valve closing direction is regulated on the basis of a reverse voltage which is generated at a stator 60 when the rotation of the magnet rotor 31 is regulated.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric valve.

Background Art

[0002] Patent Document 1 discloses an example of a conventional electric valve. Such an electric valve is incorporated into a refrigeration cycle of an air conditioner or the like. The electric valve has a valve body, a valve element, and a stepping motor for moving the valve element. The stepping motor has a magnetic rotor and a stator. When a pulse is input to the stepping motor, the magnetic rotor rotates. In response to the rotation of the magnetic rotor, the valve element moves, and the flow rate of the fluid (refrigerant) flowing through the valve port of the valve body changes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional electric valve, when the magnetic rotor rotates in the valve closing direction, it moves downward and pushes the valve element toward the valve port via a spring member. When the valve element moves downward and contacts the valve seat of the valve body, the downward movement of the valve element is restricted, but since the spring member contracts, the rotation of the magnetic rotor in the valve closing direction continues. Therefore, a stopper is provided on the magnetic rotor, and the position of the magnetic rotor when the rotation of the magnetic rotor in the valve closing direction is restricted by the stopper is used as a reference position.

[0005] Such stoppers are unrelated to the electric valve's primary function of controlling fluid flow. Furthermore, their relatively large size hinders the miniaturization of electric valves and increases their manufacturing costs. Additionally, the timing of when the valve body stops moving is out of sync with when the magnetic rotor stops rotating, requiring complex valve body position control.

[0006] Therefore, the present invention aims to provide an electric valve that eliminates the need for a stopper on the magnet rotor and can stop the rotation of the magnet rotor when the movement of the valve body stops. [Means for solving the problem]

[0007] To achieve the above objective, an electric valve according to one aspect of the present invention is an electric valve comprising: a valve body having a valve port and a valve seat surrounding the valve port; a valve element facing the valve port; a valve shaft; and a stepping motor, wherein the valve shaft and the valve body or the valve element constitute a lead screw mechanism; the valve shaft is coaxially fixed to the magnet rotor of the stepping motor; the end of the valve shaft is connected to the valve element; when the magnet rotor rotates in the valve closing direction, the valve element moves toward the valve port; and when the valve element contacts the valve seat, the valve seat restricts the movement of the valve element toward the valve port.

[0008] In the present invention, it is preferable that the valve stem and the valve body constitute the feed screw mechanism, that a male thread is formed on the valve stem, that a female thread is formed on the valve body into which the male thread is screwed, and that the male thread and the female thread constitute the feed screw mechanism.

[0009] In the present invention, it is preferable that the valve stem and the valve body constitute the feed screw mechanism, that a male thread is formed on the valve stem, that a female thread is formed on the valve body into which the male thread is screwed, and that the male thread and the female thread constitute the feed screw mechanism.

[0010] In the present invention, it is preferable that the valve stem and the valve body constitute a feed screw mechanism, that a female thread is formed on the valve stem, that a male thread is formed on the valve body into which the female thread is screwed, and that the male thread and the female thread constitute the feed screw mechanism.

[0011] In the present invention, it is preferable that the valve stem and the valve body constitute a feed screw mechanism, that a female thread is formed on the valve stem, that a male thread is formed on the valve body into which the female thread is screwed, and that the male thread and the female thread constitute the feed screw mechanism.

[0012] In the present invention, it is preferable that the valve body has a valve stem hole arranged coaxially with the valve port, the female thread is formed on the inner circumferential surface of the valve stem hole, and the end of the valve stem is integrally connected to the valve body.

[0013] In the present invention, it is preferable that the valve body has a valve stem hole arranged coaxially with the valve port, the female thread is formed on the inner circumferential surface of the valve stem hole, the end of the valve stem is in contact with the valve body, and when the magnet rotor rotates in the valve closing direction, the valve stem pushes the valve body toward the valve port.

[0014] In the present invention, it is preferable that the valve body has a bearing that rotatably supports the valve shaft, the bearing is arranged coaxially with the valve port, the valve body has a valve shaft hole, and the female thread is formed on the inner circumferential surface of the valve shaft hole.

[0015] In the present invention, it is preferable that the electric valve has a control device for controlling the stepping motor, and that in the initialization operation mode, the control device rotates the magnet rotor in the valve closing direction, acquires the position of the magnet rotor when the rotation of the magnet rotor in the valve closing direction is restricted as a reference position, and controls the position of the magnet rotor based on the reference position in the normal operation mode.

[0016] In the present invention, it is preferable that the control device has a magnetic sensor that outputs a signal corresponding to the rotation of the magnet rotor, and detects that the rotation of the magnet rotor in the valve closing direction is restricted based on the signal output by the magnetic sensor. [Effects of the Invention]

[0017] According to the present invention, the valve stem and the valve body or valve element constitute a lead screw mechanism. The valve stem is coaxially fixed to the magnet rotor of a stepping motor, and the end of the valve stem is connected to the valve element. When the magnet rotor rotates in the valve closing direction, the valve element moves toward the valve opening. When the valve element contacts the valve seat, the valve seat restricts the movement of the valve element toward the valve opening. In this way, the valve stem and valve element are moved by the lead screw mechanism composed of the valve stem and valve body. Alternatively, the valve element is moved by a lead screw mechanism composed of the valve stem and valve element. When the magnet rotor rotates in the valve closing direction, the valve stem also rotates in the valve closing direction. When the valve element contacts the valve seat, the valve seat restricts the movement of the valve element toward the valve opening, stopping the movement of the valve element. As a result, the lead screw mechanism also stops, restricting the rotation of the valve stem in the valve closing direction, and stopping the rotation of the magnet rotor. Therefore, a stopper on the magnet rotor can be omitted, and the rotation of the magnet rotor can be stopped when the movement of the valve element stops.

[0018] Also, according to the present invention, in the initialization operation mode, the control device rotates the magnetic rotor in the valve closing direction, and acquires, as a reference position, the position of the magnetic rotor when the rotation of the magnetic rotor in the valve closing direction is restricted. Then, in the normal operation mode, the control device controls the position of the magnetic rotor based on the reference position. By doing so, when the control device rotates the magnetic rotor in the valve closing direction and the magnetic rotor reaches the reference position, the rotation of the magnetic rotor can be stopped. Therefore, it is possible to suppress the rotation of the magnetic rotor in the valve closing direction beyond the reference position, and suppress the wear of the valve seat and power consumption. Further, when the control device rotates the magnetic rotor in the valve opening direction and the magnetic rotor reaches a predetermined fully open position, the rotation of the magnetic rotor can be stopped. Therefore, it is possible to suppress the rotation of the magnetic rotor in the valve opening direction beyond the fully open position, and suppress the disengagement of the male screw and the female screw of the feed screw mechanism. As a result, it is possible to omit a stopper for restricting the rotation of the magnetic rotor in the valve opening direction and a coil spring for restoring the screwing of the male screw and the female screw.

Brief Description of the Drawings

[0019] [Figure 1] It is a cross-sectional view of an electric valve according to a first embodiment of the present invention. [Figure 2] It is a cross-sectional view of a stator unit of an electric valve. [Figure 3] It is a cross-sectional view of a valve body and its vicinity when the valve body of an electric valve is in contact with a valve seat. [Figure 4] It is a cross-sectional view of a valve body and its vicinity when the valve body of an electric valve is separated from a valve seat. [Figure 5] It is a graph showing the relationship between the valve opening degree and the flow rate in an electric valve. [Figure 6] It is a functional block diagram of an electric valve. [Figure 7] It is a cross-sectional view showing the configuration of a modification of the electric valve of FIG. 1. [Figure 8] It is a cross-sectional view of an electric valve according to a second embodiment of the present invention. [Figure 9]It is a cross-sectional view of an electric valve according to a third embodiment of the present invention.

Mode for Carrying Out the Invention

[0020] (First Embodiment) Hereinafter, the electric valve 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 7. The electric valve 1 is incorporated, for example, in the refrigeration cycle of an air conditioner and operates in response to a command from the control unit 400 of the air conditioner. The control unit 400 is an external device outside the electric valve 1.

[0021] FIG. 1 is a cross-sectional view of an electric valve according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the stator unit of the electric valve. FIGS. 3 and 4 are cross-sectional views of the valve body of the electric valve and its vicinity. FIG. 3 shows a state where the valve body is in contact with the valve seat. FIG. 4 shows a state where the valve body is separated from the valve seat. In FIGS. 1, 3, and 4, the valve shaft and the valve body of the electric valve are shown in a state of being viewed from the front. FIG. 5 is a graph showing the relationship between the valve opening degree and the flow rate in the electric valve. FIG. 6 is a functional block diagram of the electric valve. FIG. 7 is a cross-sectional view showing the configuration of a modified example of the electric valve of FIG. 1.

[0022] As shown in FIGS. 1 and 2, the electric valve 1 has a valve body 10, a stem 20, a drive mechanism 30, a valve body 40, and a control device 80.

[0023] The valve body 10 is made of a metal such as an aluminum alloy. The valve body 10 has a body member 11, a flow path block 12, and a support member 13.

[0024] The body member 11 has a cylindrical shape. The body member 11 has a valve chamber 14, a valve port 15, and a valve seat 16. The valve port 15 opens into the valve chamber 14. The valve seat 16 is an annular inward tapered surface. The valve seat 16 surrounds the valve port 15 in the valve chamber 14. The inner peripheral edge 16a of the valve seat 16 is connected to the upper end 15a of the valve port 15. The body member 11 has a first mounting hole 11a. The first mounting hole 11a is disposed on the upper surface 11b of the body member 11.

[0025] The flow path block 12 has a rectangular parallelepiped shape. The flow path block 12 has a second mounting hole 12a. The second mounting hole 12a is located on the upper surface 12b of the flow path block 12. The main body member 11 is located in the second mounting hole 12a. The main body member 11 is attached to the flow path block 12 by a screw structure. The upper surface 11b of the main body member 11 and the upper surface 12b of the flow path block 12 are on the same plane. The main body member 11 and the flow path block 12 are provided with a flow path 17 and a flow path 18. The flow path 17 is connected to the valve chamber 14. The flow path 18 is connected to the valve chamber 14 via a valve port 15. In the electric valve 1, the flow path block 12 may be omitted, and the main body member 11 may have a rectangular parallelepiped shape.

[0026] The support member 13 has a cylindrical shape. The support member 13 is positioned in the first mounting hole 11a. The support member 13 is attached to the main body member 11 by a screw structure. The upper part of the support member 13 protrudes upward from the upper surface 11b of the main body member 11. The support member 13 has a valve shaft hole 13a that penetrates in the vertical direction (axis L direction). The valve shaft hole 13a faces the valve opening 15 in the vertical direction. The valve shaft hole 13a is positioned coaxially with the valve opening 15. The support member 13 has an internal thread 13c. The internal thread 13c is positioned on the inner circumferential surface of the valve shaft hole 13a.

[0027] The can 20 is made of a metal such as stainless steel. The can 20 has a cylindrical shape. The can 20 is open at the bottom and closed at the top. The bottom end of the can 20 is fixed to the upper part of the support member 13 via a ring-shaped connecting member 25.

[0028] In addition, as shown in Figure 7, the electric valve 1A may be attached to the main body member 11A by a press-fit structure. In the electric valve 1A, the upper part of the main body member 11A protrudes upward from the upper surface 12b of the flow path block 12, and the lower end of the can 20 is fixed to the upper part of the main body member 11A.

[0029] The drive mechanism 30 moves the valve body 40 in the vertical direction. The drive mechanism 30 includes a magnet rotor 31, a valve stem 34, and a stator unit 50.

[0030] The magnet rotor 31 has a cylindrical shape. The magnet rotor 31 is open at the top and closed at the bottom. The outer diameter of the magnet rotor 31 is smaller than the inner diameter of the can 20. The magnet rotor 31 has multiple north poles and multiple south poles. The multiple north poles and multiple south poles are arranged on the outer circumferential surface of the magnet rotor 31. The multiple north poles and multiple south poles extend in the vertical direction. The multiple north poles and multiple south poles are arranged alternately at equal angular intervals in the circumferential direction. For example, the magnet rotor 31 has 12 north poles and 12 south poles.

[0031] The valve stem 34 has a cylindrical shape. The upper end (one end) of the valve stem 34 is coaxially fixed to the lower end of the magnet rotor 31. The valve stem 34 has a male thread 34c. The male thread 34c is located on the outer circumferential surface of the valve stem 34. The valve stem 34 is placed in the valve stem hole 13a, and the male thread 34c is screwed into the female thread 13c. The female thread 13c and the male thread 34c constitute a feed screw mechanism 33. When the valve stem 34 rotates, the valve stem 34 moves vertically in accordance with the direction of rotation.

[0032] The valve body 40 is positioned in the valve chamber 14. The valve body 40 faces the valve port 15 in the vertical direction. The valve body 40 is connected to the lower end (other end) of the valve stem 34. The valve stem 34 and the valve body 40 are integrally formed, for example, by machining a cylindrical workpiece.

[0033] The valve body 40 includes a control unit 45 and a seating portion 47. The control unit 45 has a tapered shape (frustoconical shape) in which the diameter gradually decreases towards the valve opening 15. The seating portion 47 also has a tapered shape in which the diameter gradually decreases towards the valve opening 15. The taper angle of the control unit 45 is smaller than the taper angle of the seating portion 47. The upper end of the control unit 45 is connected to the lower end of the seating portion 47. The outer circumferential surface of the control unit 45 is the control surface 46. The outer circumferential surface of the seating portion 47 is the seating surface 48. The control surface 46 and the seating surface 48 are outward-facing tapered surfaces.

[0034] The valve body 40 is moved vertically by the drive mechanism 30. The movement of the valve body 40 opens and closes the valve port 15. As shown in Figure 3, the valve port 15 closes when the seating surface 48 contacts the inner peripheral edge 16a of the valve seat 16. As shown in Figure 4, the valve port 15 opens when the seating surface 48 moves away from the inner peripheral edge 16a of the valve seat 16. When the seating surface 48 moves away from the inner peripheral edge 16a, an annular gap (throttling passage) is formed between the inner peripheral edge 16a and the valve body 40. The area of ​​the throttling passage is closely related to the flow rate of the fluid flowing through the valve port 15.

[0035] The graph in Figure 5 shows the relationship between valve opening and flow rate in the electric valve 1. The valve opening is expressed as a percentage of the position of the valve body 40 relative to the valve seat 16 (the amount of movement from the position where the valve body 40 is in contact with the valve seat 16). The position of the valve body 40 corresponds to the position of the magnet rotor 31. In the electric valve 1, the position of the magnet rotor 31 when the seating surface 48 is in contact with the inner peripheral edge 16a of the valve seat 16 is defined as the reference position Rx, and the valve opening when the magnet rotor 31 is in the reference position Rx is defined as 0%. The position of the magnet rotor 31 at a predetermined rotation angle away from the reference position Rx is defined as the fully open position Rz, and the valve opening when the magnet rotor 31 is in the fully open position Rz is defined as 100%. The flow rate is expressed as a percentage of the flow rate of the fluid flowing through the valve port 15. The flow rate when the magnet rotor 31 is in the reference position Rx is defined as 0%, and the flow rate when it is in the fully open position Rz is defined as 100%.

[0036] When the magnetic rotor 31 is rotated in the valve-opening direction, the lead screw mechanism 33 moves the valve stem 34 and valve body 40 upward. When the magnetic rotor 31 is rotated in the valve-closing direction, the lead screw mechanism 33 moves the valve stem 34 and valve body 40 downward. When the valve body 40 moves downward and its seating surface 48 contacts the inner periphery 16a of the valve seat 16, the downward movement of the valve body 40 and valve stem 34 is restricted. When the downward movement of the valve stem 34 is restricted, the male screw 34c and the female screw 13c are tightened, and the lead screw mechanism stops. As a result, the lead screw mechanism 33 restricts the rotation of the valve stem 34 and magnetic rotor 31 in the valve-closing direction.

[0037] The stator unit 50 includes a stator 60 and a housing 70.

[0038] The stator 60 has a cylindrical shape. The stator 60 includes an A-phase stator 61, a B-phase stator 62, and a mold 63 made of synthetic resin.

[0039] The A-phase stator 61 has multiple claw-pole type pole teeth 61a and 61b on its inner circumference. The tips of the pole teeth 61a point downward, and the tips of the pole teeth 61b point upward. The pole teeth 61a and 61b are arranged alternately at equal angular intervals in the circumferential direction. For example, the A-phase stator 61 has 12 pole teeth 61a and 12 pole teeth 61b. The angle between adjacent pole teeth 61a and 61b is 15 degrees. When the coil 61c of the A-phase stator 61 is energized, the pole teeth 61a and 61b become opposite in polarity.

[0040] The B-phase stator 62 has multiple claw-pole type pole teeth 62a and 62b on its inner circumference. The tips of the pole teeth 62a point downward, and the tips of the pole teeth 62b point upward. The pole teeth 62a and 62b are arranged alternately at equal angular intervals in the circumferential direction. For example, the B-phase stator 62 has 12 pole teeth 62a and 12 pole teeth 62b. The angle between adjacent pole teeth 62a and 62b is 15 degrees. When the coil 62c of the B-phase stator 62 is energized, the pole teeth 62a and 62b become opposite in polarity.

[0041] The A-phase stator 61 and the B-phase stator 62 are arranged coaxially. The A-phase stator 61 and the B-phase stator 62 are in contact with each other. When viewed from the direction of axis L, the angle between the pole teeth 61a of the adjacent A-phase stator 61 and the pole teeth 62a of the adjacent B-phase stator 62 is 7.5 degrees.

[0042] The mold 63 is filled inside the A-phase stator 61 and the B-phase stator 62. The mold 63 also forms the inner circumferential surface 60a of the stator together with the pole teeth 61a, 61b and 62a, 62b. The diameter of the inner circumferential surface 60a of the stator is the same as the diameter of the outer circumferential surface of the can 20. The mold 63 has terminal support portions 64.

[0043] The terminal support portion 64 extends laterally (in a direction perpendicular to the axis L) from the A-phase stator 61 and the B-phase stator 62. The terminal support portion 64 supports a plurality of terminals 65. The plurality of terminals 65 protrude laterally from the tip of the terminal support portion 64. The plurality of terminals 65 are connected to the coil 61c of the A-phase stator 61 and the coil 62c of the B-phase stator 62.

[0044] In the electric valve 1, the main body member 11 (valve port 15, valve seat 16), support member 13 (valve shaft hole 13a), can 20, magnet rotor 31, valve shaft 34, valve body 40 (control unit 45, seating part 47), and stator 60 (A-phase stator 61, B-phase stator 62) each have their central axes coincide with the axis L.

[0045] A can 20 is positioned inside the stator 60. A magnet rotor 31 is positioned inside the can 20. The magnet rotor 31 and the stator 60 constitute a stepping motor 66.

[0046] In the electric valve 1, when the seating surface 48 is in contact with the inner peripheral edge 16a of the valve seat 16, the magnet rotor 31 is in the reference position Rx. When the magnet rotor 31 is in the reference position Rx, if a pulse of the maximum number z is input to the stepping motor 66, the magnet rotor 31 moves from the reference position Rx to the fully open position Rz. The maximum number z is preset, and in this embodiment, the maximum number z is 500. The step angle of the stepping motor 66 is 3.75 degrees. In this specification, "a pulse is input to the stepping motor 66" is synonymous with "a drive current corresponding to the pulse is supplied to the stator 60 of the stepping motor 66".

[0047] In the electric valve 1, the position of the magnet rotor 31 corresponds to the number of pulses input to the stepping motor 66. Specifically, the rotation angle from the reference position Rx to the fully open position Rz is divided into a maximum of z, and each position obtained is assigned a number from 0 to z. In this embodiment, each position is shown as position "0" to "500".

[0048] The housing 70 is made of synthetic resin. The housing 70 houses the stator 60 and the control device 80. The housing 70 has a peripheral wall portion 71, an upper wall portion 72, and a connector 73.

[0049] The peripheral wall portion 71 has a cylindrical shape. The stator 60 is embedded in the peripheral wall portion 71. The diameter of the inner circumferential surface 71a of the peripheral wall portion 71 is the same as the diameter of the inner circumferential surface 60a of the stator. The inner circumferential surface 71a is continuous with the inner circumferential surface 60a of the stator without any steps. The upper wall portion 72 has a dome shape. The upper wall portion 72 is connected to the upper end of the peripheral wall portion 71. The connector 73 is located on the top of the housing 70. The inner circumferential surface 71a of the peripheral wall portion 71, the inner surface 72a of the upper wall portion 72, and the inner circumferential surface 60a of the stator define the inner space 74 of the stator unit 50. The can 20 is located in the inner space 74.

[0050] The housing 70 has a substrate space 75. The substrate space 75 is adjacent to the inner space 74. A partition wall 76 is positioned between the inner space 74 and the substrate space 75. The partition wall 76 separates the inner space 74 and the substrate space 75. The housing 70 has an opening 70a that leads to the substrate space 75, and the opening 70a is closed by a cover member 77.

[0051] The control device 80 is located in the substrate space 75 of the housing 70. The control device 80 includes a main board 90, a sub-board 100, a magnetic sensor 110, and a microcomputer 120.

[0052] The main board 90 is a printed circuit board on which electronic components are mounted. The main board 90 is housed in the board space 75. The main board 90 is arranged parallel to each other in the vertical direction. A microcomputer 120 is mounted on the main board 90. Multiple terminals 65 of the stator 60 are connected to the main board 90.

[0053] The sub-board 100 is a printed circuit board on which electronic components are mounted. The sub-board 100 is housed in the board space 75. The sub-board 100 is positioned perpendicular to the main board 90. The first end 100a of the sub-board 100 is located near the main board 90. The second end 100b of the sub-board 100 is located near the partition wall 76. The sub-board 100 is connected to the main board 90 via an inter-board connector.

[0054] The magnetic sensor 110 is, for example, a Hall IC. The magnetic sensor 110 is located at the second end 100b of the sub-board 100. The magnetic sensor 110 is aligned laterally with the magnet rotor 31 via the can 20 and the partition wall 76. The magnetic sensor 110 outputs a signal (on signal, off signal) corresponding to the direction of the magnetic field generated by the magnet rotor 31. Alternatively, the motorized valve 1 may have a permanent magnet that rotates with the magnet rotor 31, and the magnetic sensor 110 may output a signal corresponding to the direction of the magnetic field generated by the permanent magnet.

[0055] The microcomputer 120 is an embedded device microcomputer that integrates, for example, a central processing unit, non-volatile memory, working memory, a communication module, a motor driver, etc., into a single package. The microcomputer 120 controls the electric valve 1. Note that the non-volatile memory, working memory, communication module, and motor driver may be individual electronic components externally connected to the microcomputer 120.

[0056] As shown in Figure 6, the control device 80 includes a storage unit 210, a communication unit 220, and a rotation control unit 230. Non-volatile memory constitutes the storage unit 210. The central processing unit executes programs stored in the non-volatile memory and functions as the communication unit 220 and the rotation control unit 230. Working memory stores variables used by the rotation control unit 230. The communication module is connected to the control unit 400 of the air conditioner via a cable (not shown) connected to a connector 73. The motor driver is connected to the stepping motor 66. Specifically, the motor driver is connected to the coil 61c of the A-phase stator 61 and the coil 62c of the B-phase stator 62. The motor driver supplies drive current to the coils 61c and 62c according to the pulse.

[0057] The memory unit 210 stores, for example, the current position Rc of the magnet rotor 31 immediately before the power supply to the electric valve 1 is cut off. Note that the current position Rc is stored in the working memory when the electric valve 1 is operating.

[0058] The communication unit 220 communicates with the control unit 400 through a communication module. The communication unit 220 receives various commands from the control unit 400 and forwards them to the rotation control unit 230. The communication unit 220 obtains the status of the electric valve 1 from the rotation control unit 230 and transmits it to the control unit 400.

[0059] The communication unit 220 receives a valve body movement command from the control unit 400. The valve body movement command includes information regarding the target position Rt of the magnet rotor 31. This information indicates the target valve opening. This information may also indicate the relative rotation angle of the magnet rotor 31 from its current position Rc (such as the number of pulses input to the stepping motor 66 and the rotation direction of the magnet rotor 31). Based on this information, the rotation control unit 230 obtains the target position Rt of the magnet rotor 31.

[0060] In the electric valve 1, valve openings from 0% to 100% correspond to positions "0" to "500" of the magnet rotor 31. Position "0" is the reference position Rx, and position "500" is the fully open position Rz. For example, when the valve opening included in the valve movement command is 0%, the target position Rt is position "0". When the valve opening included in the valve movement command is 25%, the target position Rt is position "125". When the valve opening included in the valve movement command is 50%, the target position Rt is position "250". When the valve opening included in the valve movement command is 75%, the target position Rt is position "375". When the valve opening included in the valve movement command is 100%, the target position Rt is position "500".

[0061] When the communication unit 220 receives a valve movement command, the rotation control unit 230 acquires the position of the magnet rotor 31 corresponding to the valve opening degree included in the valve movement command as the target position Rt. For example, when the valve opening degree is 20%, the rotation control unit 230 acquires position "100" as the target position Rt; when the valve opening degree is 80%, it acquires position "400" as the target position Rt; and when the valve opening degree is 100%, it acquires position "500" as the target position Rt.

[0062] When the number indicating the target position Rt of the magnet rotor 31 is greater than the number indicating the current position Rc, the rotation control unit 230 inputs a number of pulses obtained by subtracting the number indicating the current position Rc from the number indicating the target position Rt to the stepping motor 66, causing the magnet rotor 31 to rotate in the valve opening direction.

[0063] When the number indicating the target position Rt of the magnet rotor 31 is smaller than the number indicating the current position Rc, the rotation control unit 230 inputs a number of pulses obtained by subtracting the number indicating the target position Rt from the number indicating the current position Rc to the stepping motor 66, causing the magnet rotor 31 to rotate in the valve closing direction.

[0064] Furthermore, the rotation control unit 230 acquires the rotation angle of the magnet rotor 31 based on the signal output by the magnetic sensor 110 and determines the state of the magnet rotor 31 (rotating state, non-rotating state). When the magnet rotor 31 rotates, the magnetic sensor 110 alternately outputs an ON signal and an OFF signal. When the magnet rotor 31 does not rotate, the magnetic sensor 110 continuously outputs an ON signal or an OFF signal. The control device 80 detects the rotation angle of the magnet rotor 31 based on the number of times the ON signal and OFF signal have switched. When there is a change in the signal (switching between the ON signal and the OFF signal), the control device 80 determines that the magnet rotor 31 is in a "rotating state". When there is no change in the signal, the control device 80 determines that the magnet rotor 31 is in a "non-rotating state". When the rotation control unit 230 determines that the magnet rotor 31 is in a non-rotating state while it is rotating in the valve-closing direction, it detects that the rotation of the magnet rotor 31 in the valve-closing direction has been restricted.

[0065] Furthermore, the rotation control unit 230 determines the success or failure of the valve body movement command. Specifically, the rotation control unit 230 compares the rotation angle of the magnet rotor 31 (calculated rotation angle), obtained by multiplying the number of pulses input to the stepping motor 66 by the step angle, with the rotation angle of the magnet rotor 31 (measured rotation angle) obtained based on the signal from the magnetic sensor 110. If these rotation angles match, the rotation control unit 230 transmits information to the control unit 400 via the communication unit 220 indicating that the valve body movement command was successful as the command execution result. If these rotation angles do not match, the rotation control unit 230 transmits information to the control unit 400 via the communication unit 220 indicating that the valve body movement command failed as the command execution result.

[0066] Next, we will describe an example of the operation of the electric valve 1.

[0067] The control device 80 of the electric valve 1 enters startup mode when power is turned on.

[0068] In startup mode, when the current position Rc of the magnet rotor 31 is stored in the memory unit 210, the control device 80 reads the current position Rc from the memory unit 210 and stores it in the working memory, and then transitions to normal operation mode. In normal operation mode, the control device 80 waits for commands from the control unit 400.

[0069] In startup mode, if the current position Rc is not stored in the memory unit 210, the control device 80 transitions to initialization operation mode. Alternatively, in normal operation mode, if the control device 80 receives an initialization command from the control unit 400, it transitions to initialization operation mode.

[0070] In the initialization operation mode, the control device 80 inputs pulses to the stepping motor 66 to rotate the magnet rotor 31 in the valve closing direction. The control device 80 determines that it is rotating when there is a change in the signal from the magnetic sensor 110. The control device 80 determines that it is not rotating when there is no change in the signal from the magnetic sensor. When the control device 80 determines that it is not rotating, it detects that the rotation of the magnet rotor 31 in the valve closing direction is restricted. The control device 80 then stores the reference position Rx, which is position "0", as the current position Rc in the working memory and switches to the normal operation mode.

[0071] In normal operation mode, when the control device 80 receives a valve body movement command from the control unit 400, it rotates the magnet rotor 31 to move the valve body 40 so that it matches the valve opening degree specified in the valve body movement command.

[0072] For example, if the current position Rc is position "0" and the valve opening degree included in the valve movement command is 80%, the control device 80 acquires position "400" as the target position Rt. The control device 80 inputs 400 (400 = 400 - 0) pulses to the stepping motor 66 to rotate the magnet rotor 31 in the valve opening direction. As a result, the lead screw mechanism 33 moves the valve stem 34 and the magnet rotor 31 upward, and the valve body 40 is separated from the valve seat 16 and positioned at the valve body position corresponding to position "400" (valve opening degree 80%). When the input of pulses to the stepping motor 66 is finished, the control device 80 stores position "400" as the current position Rc in its working memory. The control device 80 also determines the success or failure of the valve movement command and transmits the command execution result to the control unit 400. The control device 80 then waits for the next command from the control unit 400.

[0073] For example, if the current position Rc is position "400" and the valve opening degree included in the valve movement command is 30%, the control device 80 acquires position "150" as the target position Rt. The control device 80 inputs 250 pulses (250 = 400 - 150) to the stepping motor 66 to rotate the magnet rotor 31 in the valve closing direction. As a result, the lead screw mechanism 33 moves the valve stem 34 and the magnet rotor 31 downward, and the valve body 40 approaches the valve seat 16 and is positioned at the valve body position corresponding to position "150" (valve opening degree 30%). When the input of pulses to the stepping motor 66 is finished, the control device 80 stores position "150" as the current position Rc in its working memory. The control device 80 also determines the success or failure of the valve movement command and transmits the command execution result to the control unit 400. The control device 80 then waits for the next command from the control unit 400.

[0074] For example, if the current position Rc is position "150" and the valve opening degree included in the valve movement command is 100%, the control device 80 acquires position "500" as the target position Rt. The control device 80 inputs 350 pulses (350 = 500 - 150) to the stepping motor 66 to rotate the magnet rotor 31 in the valve opening direction. As a result, the lead screw mechanism 33 moves the valve stem 34 and the magnet rotor 31 upward, and the valve body 40 is separated from the valve seat 16 and positioned at the valve body position corresponding to position "500" (valve opening degree 100%). When the input of pulses to the stepping motor 66 is finished, the control device 80 stores position "500" as the current position Rc in its working memory. The control device 80 also determines the success or failure of the valve movement command and transmits the command execution result to the control unit 400. The control device 80 then waits for the next command from the control unit 400.

[0075] For example, if the current position Rc is position "500" and the valve opening degree included in the valve movement command is 0%, the control device 80 acquires position "0" as the target position Rt. The control device 80 inputs 500 (500 = 500 - 0) pulses to the stepping motor 66 to rotate the magnet rotor 31 in the valve closing direction. As a result, the lead screw mechanism 33 moves the valve stem 34 and the magnet rotor 31 downward, and the valve body 40 comes into contact with the valve seat 16 and is positioned at the valve body position corresponding to position "0" (valve opening degree 0%). When the input of pulses to the stepping motor 66 is finished, the control device 80 stores position "0" as the current position Rc in its working memory. The control device 80 also determines the success or failure of the valve movement command and transmits the command execution result to the control unit 400. The control device 80 then waits for the next command from the control unit 400.

[0076] When the valve opening degree included in the valve movement command is less than 0% (i.e., a negative value) or greater than 100%, the control device 80 transmits a command execution result indicating that an invalid valve opening degree has been received to the control unit 400. The control device 80 then waits for the next command from the control unit 400.

[0077] When the control device 80 receives a power cut-off command from the control unit 400, it stores the current position Rc in the working memory in the storage unit 210 in preparation for power cut-off.

[0078] The electric valve 1 comprises a valve body 10 having a valve port 15 and a valve seat 16 surrounding the valve port 15, a valve element 40 facing the valve port 15, a valve stem 34, and a stepping motor 66. A male thread 34c is formed on the valve stem 34. The valve body 10 has a valve stem hole 13a arranged coaxially with the valve port 15. A female thread 13c is formed on the inner circumferential surface of the valve stem hole 13a into which the male thread 34c is screwed. The male thread 34c and the female thread 13c constitute a feed screw mechanism 33. The upper end of the valve stem 34 is coaxially fixed to the magnet rotor 31 of the stepping motor 66. The lower end (end) of the valve stem 34 is integrally connected to the valve element 40. When the magnet rotor 31 rotates in the valve closing direction, the valve element 40 moves toward the valve port 15. When the valve body 40 comes into contact with the valve seat 16, the valve seat 16 restricts the movement of the valve body 40 toward the valve opening 15.

[0079] As a result, the lead screw mechanism 33 moves the valve stem 34 and the valve body 40. When the magnetic rotor 31 rotates in the valve closing direction, the valve stem 34 also rotates in the valve closing direction. When the valve body 40 contacts the valve seat 16, the movement of the valve body 40 toward the valve opening 15 is restricted, and the movement of the valve body 40 and the valve stem 34 stops. The male screw 34c and the female screw 13c are tightened, and the lead screw mechanism 33 stops. As a result, the lead screw mechanism 33 restricts the rotation of the valve stem 34 in the valve closing direction, and the rotation of the magnetic rotor 31 stops. Therefore, a stopper on the magnetic rotor 31 can be omitted, and the rotation of the magnetic rotor 31 can be stopped when the movement of the valve body 40 stops.

[0080] Furthermore, the electric valve 1 has a control device 80 that controls the stepping motor 66. In the initialization operation mode, the control device 80 rotates the magnet rotor 31 in the valve closing direction and acquires the position of the magnet rotor 31 when its rotation in the valve closing direction is restricted as the reference position Rx. In the normal operation mode, the control device 80 controls the position of the magnet rotor 31 based on the reference position Rx. In the normal operation mode, the control device 80 does not rotate the magnet rotor 31 beyond the reference position Rx in the valve closing direction, nor does it rotate the magnet rotor 31 beyond the fully open position Rz in the valve opening direction. The control device 80 manages the position of the magnet rotor 31 by the rotation angle from the reference position Rx (the number of pulses input to the stepping motor 66).

[0081] As a result, the control device 80 can rotate the magnet rotor 31 in the valve-closing direction, and when the magnet rotor 31 reaches the reference position Rx, it can stop the rotation of the magnet rotor 31. Therefore, it is possible to suppress the magnet rotor 31 from rotating beyond the reference position Rx in the valve-closing direction, thereby suppressing wear on the valve seat 16 and power consumption. Furthermore, the control device 80 can rotate the magnet rotor 31 in the valve-opening direction, and when the magnet rotor 31 reaches the fully open position Rz, it can stop the rotation of the magnet rotor 31. Therefore, it is possible to suppress the magnet rotor 31 from rotating beyond the fully open position Rz in the valve-opening direction, thereby suppressing the disengagement of the male screw 34c and the female screw 13c. This eliminates the need for a stopper to restrict the rotation of the magnet rotor 31 in the valve-opening direction and a coil spring to restore the screw engagement between the male screw 34c and the female screw 13c.

[0082] Furthermore, the control device 80 has a magnetic sensor 110 that outputs a signal corresponding to the rotation of the magnet rotor 31. The control device 80 detects that the rotation of the magnet rotor 31 in the valve-closing direction is restricted based on the signal output by the magnetic sensor 110. In this way, it is possible to detect whether or not the rotation of the magnet rotor 31 in the valve-closing direction is restricted with a relatively simple configuration. Alternatively, the control device 80 may detect that the rotation of the magnet rotor 31 in the valve-closing direction is restricted based on the back electromotive force generated in the stator 60 when the rotation of the magnet rotor 31 is restricted.

[0083] (Second example) Hereinafter, an electric valve 2 according to a second embodiment of the present invention will be described with reference to Figure 8. Figure 8 is a cross-sectional view of the electric valve according to the second embodiment of the present invention.

[0084] As shown in Figure 8, the electric valve 2 includes a valve body 10B, a can 20, a drive mechanism 30B, a valve element 40B, and a control device 80. In the following description, components identical (including substantially identical) to those of the electric valve 1 are denoted by the same reference numerals as those of the electric valve 1, and detailed descriptions are omitted.

[0085] The valve body 10B is made of a metal such as an aluminum alloy. The valve body 10B includes a main body member 11, a flow path block 12, and a support member 13B.

[0086] The support member 13B has a first support portion 131 and a second support portion 132. The first support portion 131 has a cylindrical shape. The first support portion 131 is positioned in the first mounting hole 11a. The first support portion 131 is attached to the main body member 11 by a screw structure. The second support portion 132 is fixed to the upper part of the first support portion 131. The second support portion 132 has a valve shaft hole 132a that penetrates in the vertical direction. The valve shaft hole 132a faces the upper end surface 40b (one end surface) of the valve body 40B in the vertical direction. The valve shaft hole 132a is positioned coaxially with the valve port 15. The second support portion 132 has an internal thread 132c. The internal thread 132c is positioned on the inner circumferential surface of the valve shaft hole 132a.

[0087] The drive mechanism 30B moves the valve body 40B in the vertical direction. The drive mechanism 30B includes a magnet rotor 31B, a valve shaft 34B, and a stator unit 50.

[0088] The magnet rotor 31B has a cylindrical shape. A wall portion 31d is located inside the magnet rotor 31B. The wall portion 31d is located in the vertical center of the magnet rotor 31B. The magnet rotor 31B and the stator 60 constitute the stepping motor 66B.

[0089] The valve stem 34B has a cylindrical shape. The upper end of the valve stem 34B is coaxially fixed to the wall portion 31d of the magnet rotor 31B. The valve stem 34B has a male thread 34c. The male thread 34c is located on the outer circumferential surface of the valve stem 34B. The valve stem 34B is placed in the valve stem hole 132a, and the male thread 34c is screwed into the female thread 132c. The female thread 132c and the male thread 34c constitute a feed screw mechanism 33B. When the valve stem 34B rotates, the valve stem 34B moves vertically in accordance with the direction of rotation.

[0090] The valve body 40B has a cylindrical shape. The valve body 40B is supported by the first support portion 131 so as to be movable in the vertical direction. The upper part of the valve body 40B is located inside the first support portion 131, and the lower part of the valve body 40B is located in the valve chamber 14. The valve body 40B faces the valve port 15 in the vertical direction. A control portion 45 and a seat portion 47 are formed on the lower part of the valve body 40B. The valve body 40B is connected to the lower end of the valve stem 34B. Specifically, the lower end of the valve stem 34B is in contact with the upper end surface 40b of the valve body 40B. A flange-shaped spring receiving portion 49 that protrudes radially outward is formed on the upper end of the valve body 40B. An opening spring 37 is located between the spring receiving portion 49 and the first support portion 131. The opening spring 37 is a compression coil spring that pushes the valve body 40B upward.

[0091] When the magnetic rotor 31B is rotated in the valve-opening direction, the lead screw mechanism 33B moves the valve stem 34B upward, and the valve body 40B is pushed upward by the valve-opening spring 37. When the magnetic rotor 31B is rotated in the valve-closing direction, the lead screw mechanism 33B moves the valve stem 34B downward, and the valve body 40B is pushed downward by the valve stem 34B. When the valve body 40B moves downward and the seating surface 48 contacts the inner circumferential edge 16a of the valve seat 16, the downward movement of the valve body 40B and valve stem 34B is restricted. As a result, the lead screw mechanism 33B restricts the rotation of the valve stem 34B and magnetic rotor 31B in the valve-closing direction.

[0092] The electric valve 2 comprises a valve body 10B having a valve port 15 and a valve seat 16 surrounding the valve port 15, a valve element 40B facing the valve port 15, a valve shaft 34B, and a stepping motor 66B. A male thread 34c is formed on the valve shaft 34B. The valve body 10B has a valve shaft hole 132a arranged coaxially with the valve port 15. A female thread 132c is formed on the inner circumferential surface of the valve shaft hole 132a into which the male thread 34c is screwed. The male thread 34c and the female thread 132c constitute a feed screw mechanism 33B. The upper end of the valve shaft 34B is coaxially fixed to the magnet rotor 31B of the stepping motor 66B. The lower end (end) of the valve shaft 34B is in contact with the valve element 40B and connected to the valve element 40B. When the magnetic rotor 31B rotates in the valve closing direction, the valve stem 34B pushes the valve body 40B toward the valve port 15, causing the valve body 40B to move toward the valve port 15. When the valve body 40B comes into contact with the valve seat 16, the valve seat 16 restricts the movement of the valve body 40B toward the valve port 15.

[0093] As a result, the lead screw mechanism 33B moves the valve stem 34B and the valve body 40B. When the magnetic rotor 31B rotates in the valve closing direction, the valve stem 34B also rotates in the valve closing direction. When the valve body 40B contacts the valve seat 16, the movement of the valve body 40B toward the valve port 15 is restricted, and the movement of the valve body 40B and the valve stem 34B stops. The male screw 34c and the female screw 132c are tightened, and the lead screw mechanism 33B stops. As a result, the rotation of the valve stem 34B in the valve closing direction is restricted by the lead screw mechanism 33B, and the rotation of the magnetic rotor 31B stops. Therefore, a stopper on the magnetic rotor 31B can be omitted, and the rotation of the magnetic rotor 31B can be stopped when the movement of the valve body 40B stops.

[0094] The electric valve 2 has the same effect as (including substantially the same effect as) the electric valve 1.

[0095] (Third embodiment) Hereinafter, an electric valve 3 according to a third embodiment of the present invention will be described with reference to Figure 9. Figure 9 is a cross-sectional view of the electric valve according to the third embodiment of the present invention.

[0096] As shown in Figure 9, the electric valve 3 comprises a valve body 10C, a can 20, a drive mechanism 30C, a valve element 40C, and a control device 80. In the following description, components identical (including substantially identical) to those of the electric valve 1 are denoted by the same reference numerals as those of the electric valve 1, and detailed descriptions are omitted.

[0097] The valve body 10C is made of a metal such as an aluminum alloy. The valve body 10C includes a main body member 11, a flow path block 12, a support member 13C, and a bearing 19C.

[0098] The support member 13C has a cylindrical shape. The support member 13C is positioned in the first mounting hole 11a. The support member 13C is attached to the main body member 11 by a screw structure. The upper part of the support member 13C protrudes upward from the upper surface 11b of the main body member 11.

[0099] The bearing 19C is a ball bearing. The bearing 19C is coaxially fixed to the upper part of the support member 13C. The bearing 19C is positioned coaxially with the valve port 15. The bearing 19C rotatably supports the valve stem 34C.

[0100] The drive mechanism 30C moves the valve body 40C in the vertical direction. The drive mechanism 30C includes a magnet rotor 31C, a valve shaft 34C, and a stator unit 50.

[0101] The magnet rotor 31C has a cylindrical shape. A wall portion 31e is located inside the magnet rotor 31C. The wall portion 31e is located near the lower end of the magnet rotor 31C. The magnet rotor 31C and the stator 60 constitute the stepping motor 66C.

[0102] The valve stem 34C has a cylindrical shape. The upper end of the valve stem 34C is coaxially fixed to the wall portion 31e of the magnet rotor 31C via a connecting member 34e. The valve stem 34C has a male thread 34c. The male thread 34c is located on the outer circumferential surface of the valve stem 34C.

[0103] The valve body 40C has a cylindrical shape. The valve body 40C is supported by a support member 13C so as to be movable in the vertical direction. The valve body 40C is restricted from rotating about its central axis. The upper part of the valve body 40C is located inside the support member 13C, and the lower part of the valve body 40C is located in the valve chamber 14. The valve body 40C faces the valve port 15 in the vertical direction. The valve body 40C has a valve shaft hole 40a. The valve shaft hole 40a is located on the upper end surface 40b of the valve body 40C. The valve body 40C has a female thread 40c. The female thread 40c is located on the inner circumferential surface of the valve shaft hole 40a. A control unit 45 and a seating portion 47 are formed in the lower part of the valve body 40C. The valve body 40C is connected to the lower end of the valve shaft 34C. Specifically, the valve stem 34C is positioned in the valve stem hole 40a, and the male thread 34c is screwed into the female thread 40c. The female thread 40c and the male thread 34c constitute a lead screw mechanism 33C. The lead screw mechanism 33C connects the valve stem 34C and the valve body 40C. When the valve stem 34C rotates, the valve body 40C moves vertically in accordance with the direction of rotation of the valve stem 34C. The valve stem 34C does not move vertically.

[0104] When the magnetic rotor 31C is rotated in the valve-opening direction, the valve stem 34C is also rotated in the valve-opening direction, and the valve body 40C moves upward by the lead screw mechanism 33C. When the magnetic rotor 31C is rotated in the valve-closing direction, the valve stem 34C is also rotated in the valve-closing direction, and the valve body 40C moves downward by the lead screw mechanism 33C. When the valve body 40C moves downward and the seating surface 48 contacts the inner peripheral edge 16a of the valve seat 16, the downward movement of the valve body 40C is restricted. As a result, the lead screw mechanism 33C restricts the rotation of the valve stem 34C and the magnetic rotor 31C in the valve-closing direction.

[0105] The electric valve 3 comprises a valve body 10C having a valve port 15 and a valve seat 16 surrounding the valve port 15, a valve element 40C facing the valve port 15, a valve shaft 34C, and a stepping motor 66C. The valve body 10C has a bearing 19C that rotatably supports the valve shaft 34C. The bearing 19C is arranged coaxially with the valve port 15. A male thread 34c is formed on the valve shaft 34C. The valve element 40C has a valve shaft hole 40a. A female thread 40c is formed on the inner circumferential surface of the valve shaft hole 40a into which the male thread 34c is screwed. The male thread 34c and the female thread 40c constitute a lead screw mechanism 33C. The upper end of the valve shaft 34C is coaxially fixed to the magnet rotor 31C of the stepping motor 66C. The lower end (end) of the valve shaft 34C is connected to the valve element 40C. When the magnetic rotor 31C rotates in the closing direction, the valve body 40C moves toward the valve opening 15. When the valve body 40C comes into contact with the valve seat 16, the valve seat 16 restricts the movement of the valve body 40C toward the valve opening 15.

[0106] As a result, the valve body 40C is moved by the lead screw mechanism 33C. When the magnet rotor 31C rotates in the valve closing direction, the valve stem 34C also rotates in the valve closing direction. When the valve body 40C contacts the valve seat 16, the movement of the valve body 40C toward the valve port 15 is restricted, and the movement of the valve body 40C stops. The male screw 34c and the female screw 40c are tightened, and the lead screw mechanism 33C stops. As a result, the rotation of the valve stem 34C in the valve closing direction is restricted by the lead screw mechanism 33C, and the rotation of the magnet rotor 31C stops. Therefore, a stopper on the magnet rotor 31C can be omitted, and the rotation of the magnet rotor 31C can be stopped when the movement of the valve body 40C stops.

[0107] The electric valve 3 has the same effect as (including substantially the same effect as) the electric valve 1.

[0108] In the electric valves 1 to 3 described above, a male thread is formed on the valve stem, and a female thread is formed on the valve body or valve element into which the male thread is screwed, and the male thread and female thread constitute a lead screw mechanism. In the electric valve according to the present invention, a female thread may be formed on the valve stem, and a male thread may be formed on the valve body or valve element into which the female thread is screwed, and the male thread and female thread may constitute a lead screw mechanism. In other words, the electric valve according to the present invention only needs to have a valve stem and valve body or valve element that constitute a lead screw mechanism.

[0109] In this specification, terms indicating shapes such as "cylinder" and "column" are also used to refer to members or parts of members that substantially have the shape of those terms. For example, "cylindrical member" includes both cylindrical members and substantially cylindrical members.

[0110] Although embodiments of the present invention have been described above, the present invention is not limited to the configurations of these embodiments. Additions, deletions, design modifications, and combinations of features of the embodiments, as appropriate by those skilled in the art, are also included within the scope of the present invention, as long as they do not contradict the spirit of the invention. [Explanation of symbols]

[0111] (First embodiment) 1, 1A...Electric valve, 10...Valve body, 11, 11A...Body member, 11a...First mounting hole, 11b...Top surface, 12...Flow path block, 12a...Second mounting hole, 12b...Top surface, 13, 13A...Support member, 13a...Valve shaft hole, 13c...Female thread, 14...Valve chamber, 15...Valve opening, 15a...Upper end, 16...Valve seat, 16a...Inner periphery, 17...Flow path, 18...Flow path, 20...K Chan, 25...Connecting member, 30...Drive mechanism, 31...Magnet rotor, 31d...Wall section, 31e...Wall section, 33...Lead screw mechanism, 34...Valve shaft, 34c...Male screw, 34e...Connecting member, 40...Valve body, 45...Control unit, 46...Control surface, 47...Seating section, 48...Seating surface, 50...Stator unit, 60...Stator, 60a...Inner circumferential surface of stator, 6 1…A-phase stator, 61a…Pole teeth, 61b…Pole teeth, 61c…Coil, 62…B-phase stator, 62a…Pole teeth, 62b…Pole teeth, 62c…Coil, 63…Mold, 64…Terminal support part, 65…Terminal, 66…Stepping motor, 70…Housing, 70a…Opening, 71…Peripheral wall part, 71a…Inner peripheral surface, 72…Upper wall part, 72a…Inner surface, 73…Connector, 74…Inner space, 75…Substrate space, 76…Partition wall, 77…Lid member, 80…Control device, 90…Main board, 100…Sub board, 100a…First end, 100b…Second end, 110…Magnetic sensor, 120…Microcomputer, 210…Storage unit, 220…Communication unit, 230…Rotation control unit, 400…Control unit, L…Axis (Second example) 2...Electric valve, 10B...Valve body, 13B...Support member, 30B...Drive mechanism, 31B...Magnet rotor, 33B...Lead screw mechanism, 34B...Valve stem, 37...Opening spring, 40B...Valve body, 40b...Upper end face, 49...Spring receptacle, 66B...Stepping motor, 131...First support part, 132...Second support part, 132a...Valve stem hole, 132c...Female thread (Third embodiment) 3...Electric valve, 10C...Valve body, 13C...Support member, 19C...Bearing, 30C...Drive mechanism, 31C...Magnet rotor, 33C...Lead screw mechanism, 34C...Valve shaft, 40C...Valve body, 40a...Valve shaft hole, 40b...Upper end face, 40c...Female thread, 66C...Stepping motor

Claims

[Claim 1] An electric valve comprising: a valve body having a valve port and a valve seat surrounding the valve port; a valve element facing the valve port; a valve stem; a stepping motor; and a control device for controlling the stepping motor, The valve shaft and the valve body or valve element constitute a feed screw mechanism. The valve shaft is fixed coaxially to the magnet rotor of the stepping motor. The end of the valve stem is connected to the valve body, When the magnetic rotor rotates in the valve closing direction, the valve body moves toward the valve opening. When the valve body comes into contact with the valve seat, the valve seat restricts the movement of the valve body toward the valve opening. The control device, (A) When the rotation of the magnet rotor is restricted, the system detects that the rotation of the magnet rotor in the valve closing direction is restricted based on the back electromotive force generated in the stator of the stepping motor. (B) In the initialization operation mode, the magnet rotor is rotated in the valve closing direction, and the position of the magnet rotor when its rotation in the valve closing direction is restricted is obtained as the reference position. (C) In normal operation mode, the position of the magnet rotor is controlled based on the reference position, When the maximum number of pulses is input to the stepping motor while the magnet rotor is in the reference position, the magnet rotor rotates from the reference position to the fully open position. The valve movement command received by the control device includes a valve opening degree corresponding to the target position of the magnet rotor, wherein a valve opening degree of 0% corresponds to the reference position, and a valve opening degree of 100% corresponds to the fully open position. The control device, (D) The valve body movement command is received from an external device, (E) When the valve opening is 0% or more and 100% or less, the magnet rotor is rotated so that the position of the magnet rotor is the target position corresponding to the valve opening. (F) An electric valve that transmits a command execution result indicating that an invalid valve opening has been received to the external device when the valve opening is less than 0 [%] or greater than 100 [%].

Images