Electric valve

Abstract

[Task] To provide an electric valve which may have a configuration in which a stopper to be provided on a magnetic rotor is omitted, and which can stop the rotation of the magnetic rotor when a valve element ceases to move. [Solution] An electric valve (1) comprises a valve body (10) having a valve port (15) and a valve seat (16) enclosing the valve port (15), a valve element (40) facing the valve port (15), a valve stem (34), and a stepper motor (66). The valve stem (34) has an external thread (34c). The valve body (10) has an internal thread (13c) into which the external thread (34c) is screwed. The external thread (34c) and the internal thread (13c) form a screw feed mechanism (33). The valve stem (34) is coaxially attached to a magnetic rotor (31) of the stepper motor (66). The lower end of the valve stem (34) is connected to the valve element (40). When the magnetic rotor (31) rotates in a valve closing direction, the valve element (40) moves toward the valve port (15). When the valve element (40) comes into contact with the valve seat (16), its movement toward the valve port (15) is restricted.

Description

Technical area

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

[0002] Patent Document 1 discloses an example of an electric valve according to the related art. The electric valve is installed in a refrigeration cycle system of an air conditioner. The electric valve includes a valve body, a valve element, and a stepping motor for moving the valve element. The stepping motor includes a magnetic rotor and a stator. The magnetic rotor rotates in response to pulses input to the stepping motor. The valve element moves along with the rotation of the magnetic rotor, thereby changing the flow rate of fluid (refrigerant) flowing through a valve port of the valve body. State of the art documentPatent document Patent Document 1: Japanese Unexamined Patent Application Publication 2018-179133 Summary of the Invention Problem to be solved by the invention

[0003] In the related art electric valve, the magnetic rotor moves downward while rotating in a valve-closing direction, urging the valve element toward the valve port via a spring. When the valve element moves downward and comes into contact with a valve seat of the valve body, the downward movement of the valve element is restricted, but the compression of the spring allows the magnetic rotor to continue rotating in the valve-closing direction. In this configuration, a stopper is provided on the magnetic rotor, and a position of the magnetic rotor when the rotation of the magnetic rotor in the valve-closing direction is restricted by the stopper is called a reference position.

[0004] This stopper doesn't fulfill an essential function of the electric valve for controlling fluid and is comparatively large, which hinders size reduction and increases the manufacturing cost of the electric valve. Furthermore, the timing at which the magnetic rotor stops rotating does not coincide with the timing at which the valve element stops moving, necessitating complicated position control of the valve element.

[0005] Accordingly, it is an object of the present invention to provide an electric valve which can have a configuration in which a stopper to be provided on a magnet rotor is omitted and can stop the rotation of the magnet rotor when a valve element stops moving. Means of solving the task

[0006] To achieve the above object, an electric valve according to one aspect of the present invention includes 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, and a stepping motor. The valve stem and the valve body form a screw feed mechanism, or the valve stem and the valve element form a screw feed mechanism. The valve stem is coaxially fixed to a magnetic rotor of the stepping motor. One end of the valve stem is connected to the valve element. When the magnetic rotor rotates in a valve-closing direction, the valve element moves toward the valve port. When the valve element comes into contact with the valve seat, the valve seat restricts the movement of the valve element toward the valve port.

[0007] In the present invention, the valve stem and the valve body preferably form the screw feed mechanism. Preferably, the valve stem has an external thread, the valve body has an internal thread into which the external thread is screwed, and the external thread and the internal thread form the screw feed mechanism.

[0008] In the present invention, the valve stem and the valve element preferably form the screw feed mechanism. Preferably, the valve stem has an external thread, the valve element has an internal thread into which the external thread is screwed, and the external thread and the internal thread form the screw feed mechanism.

[0009] In the present invention, the valve stem and the valve body preferably form the screw feed mechanism. Preferably, the valve stem has an internal thread, the valve body has an external thread that is screwed into the internal thread, and the external thread and the internal thread form the screw feed mechanism.

[0010] In the present invention, the valve stem and the valve element preferably form the screw feed mechanism. Preferably, the valve stem has an internal thread, the valve element has an external thread that is screwed into the internal thread, and the external thread and the internal thread form the screw feed mechanism.

[0011] In the present invention, it is preferable that the valve body has a valve stem bore arranged coaxially with the valve port, the internal thread is provided on an inner peripheral surface of the valve stem bore, and the end of the valve stem is integrally connected to the valve element.

[0012] In the present invention, it is preferable that the valve body has a valve stem bore arranged coaxially with the valve port, the internal thread is provided on an inner peripheral surface of the valve stem bore, the end of the valve stem is in contact with the valve element, and the valve stem pushes the valve element toward the valve port when the magnet rotor rotates in the valve closing direction.

[0013] In the present invention, it is preferable that the valve body has a bearing that rotatably supports the valve stem, the bearing is arranged coaxially with the valve port, the valve element has a valve stem bore, and the internal thread is provided on an inner peripheral surface of the valve stem bore.

[0014] In the present invention, it is preferred that the electric valve includes a controller for controlling the stepper motor. Preferably, in an initialization operation mode, the controller rotates the magnet rotor in the valve-closing direction and obtains a position of the magnet rotor as a reference position when the rotation of the magnet rotor in the valve-closing direction is restricted. In a normal operation mode, the controller positions the magnet rotor based on the reference position.

[0015] In the present invention, it is preferable that the controller includes a magnetic sensor that outputs a signal corresponding to the rotation of the magnetic rotor, and the controller detects that the rotation of the magnetic rotor in the valve closing direction is restricted based on the signal output from the magnetic sensor. Advantages of the invention

[0016] According to the present invention, the valve stem and the valve body constitute the screw feed mechanism, or the valve stem and the valve element constitute the screw feed mechanism. The valve stem is coaxially fixed to the magnetic rotor of the stepping motor, and the end of the valve stem is connected to the valve element. When the magnetic rotor rotates in the valve-closing direction, the valve element moves toward the valve port. When the valve element comes into contact with the valve seat, the valve seat restricts the movement of the valve element toward the valve port. In this configuration, the screw feed mechanism consisting of the valve stem and the valve body moves the valve stem and the valve element, or the screw feed mechanism consisting of the valve stem and the valve element moves the valve element.When the magnetic rotor rotates in the valve-closing direction, the valve stem also rotates in the valve-closing direction. When the valve element comes into contact with the valve seat, the valve seat restricts the movement of the valve element toward the valve port and stops the movement of the valve element. Therefore, the screw feed mechanism is also stopped, restricting the rotation of the valve stem in the valve-closing direction and stopping the rotation of the magnetic rotor. As a result, a stopper required for a magnetic rotor can be omitted, and the rotation of the magnetic rotor can be stopped when the valve element stops moving.

[0017] According to the present invention, in the initialization operation mode, the controller rotates the magnet rotor in the valve-closing direction and obtains, as the reference position, the position of the magnet rotor when the rotation of the magnet rotor in the valve-closing direction is restricted. In the normal operation mode, the controller positions the magnet rotor based on the reference position. With this configuration, the controller can stop the rotation of the magnet rotor when the magnet rotor is rotated in the valve-closing direction and reaches the reference position. Therefore, the rotation of the magnet rotor in the valve-closing direction beyond the reference position can be suppressed, which reduces valve seat wear and power consumption. Furthermore, the controller can stop the rotation of the magnet rotor when the magnet rotor is rotated in the valve-opening direction and reaches a predetermined fully open position.Therefore, the rotation of the magnetic rotor in the valve-opening direction beyond the fully open position can be suppressed, preventing the male and female threads of the screw-feeding mechanism from being unscrewed. As a result, a stopper for restricting the rotation of the magnetic rotor in the valve-opening direction can be omitted, as can a coil spring for returning the male and female threads to the screwed position. Short description of the drawings [ Fig. 1] Fig. 1 is a sectional view of an electric valve according to a first embodiment of the present invention. [ Fig. 2] Fig. 2 is a sectional view of a stator unit of the electric valve. [ Fig. 3] Fig. 3 is a sectional view of a valve element and elements in its vicinity of the electric valve when the valve element is in contact with a valve seat. [ Fig. 4] Fig. 4 is a sectional view of the valve element and the elements in its vicinity of the electric valve when the valve element is separated from the valve seat. [ Fig. 5] Fig. 5 is a graph showing a relationship between a valve opening degree and a flow rate in the electric valve. [ Fig. 6] Fig. 6 is a functional block diagram of the electric valve. [ Fig. 7] Fig. 7 is a sectional view showing a configuration of a modification of the electric valve in Fig. 1 represents. [ Fig. 8] Fig. 8 is a sectional view of an electric valve according to a second embodiment of the present invention. [ Fig. 9] Fig. 9 is a sectional view of an electric valve according to a third embodiment of the present invention. Embodiments of the Invention (First Embodiment)

[0018] An electric valve 1 according to a first embodiment of the present invention will be described below with reference to the Fig. 1 to 7. For example, the electric valve 1 is installed in a refrigeration cycle system of an air conditioner and is operated in response to a command transmitted from a control unit 400 of the air conditioner. The control unit 400 is an external device separate from the electric valve 1.

[0019] Fig. 1 is a sectional view of an electric valve according to the first embodiment of the present invention. Fig. 2 is a sectional view of a stator unit of the electric valve. The Fig. 3 and Fig. 4 are sectional views of a valve element and elements in its vicinity of the electric valve. Fig. 3 represents a state in which the valve element is in contact with a valve seat. Fig. 4 shows a state in which the valve element is separated from the valve seat. Fig. 1, Fig. 3 and Fig. 4 shows a valve stem and the valve element of the electric valve in front view. Fig. 5 is a graph showing a relationship between a valve opening degree and a flow rate in the electric valve. Fig. 6 is a functional block diagram of the electric valve. Fig. 7 is a sectional view showing a configuration of a modification of the electric valve in Fig. 1 represents.

[0020] As in the Fig. 1 and Fig. 2, the electric valve 1 includes a valve body 10, a can 20, a drive mechanism 30, a valve element 40 and a controller 80.

[0021] The valve body 10 is made of a metal, such as an aluminum alloy. The valve body 10 includes a body element 11, a flow channel block 12, and a support element 13.

[0022] The body element 11 has a circular cylindrical shape. The body element 11 has a valve chamber 14, a valve port 15, and a valve seat 16. The valve port 15 is open to the valve chamber 14. The valve seat 16 is an inwardly conical surface with a circular ring shape. The valve seat 16 encloses the valve port 15 in the valve chamber 14. An inner peripheral edge 16a of the valve seat 16 is connected to an upper end 15a of the valve port 15. The body element 11 has a first mounting hole 11a. The first mounting hole 11a is provided on an upper surface 11b of the body element 11.

[0023] The flow channel block 12 has a rectangular parallelepiped shape. The flow channel block 12 has a second mounting hole 12a. The second mounting hole 12a is provided on an upper surface 12b of the flow channel block 12. The body member 11 is arranged in the second mounting hole 12a. The body member 11 is mounted in the flow channel block 12 by a screw construction. The upper surface 11b of the body member 11 is flush with the upper surface 12b of the flow channel block 12. The flow channels 17 and 18 are provided in the body member 11 and the flow channel block 12. The flow channel 17 is connected to the valve chamber 14. The flow channel 18 is connected to the valve chamber 14 through the valve port 15. In the electric valve 1, the flow channel block 12 may be omitted, and the body member 11 may have a rectangular parallelepiped shape.

[0024] The support member 13 has a circular cylindrical shape. The support member 13 is arranged in the first mounting hole 11a. The support member 13 is mounted in the body member 11 by a screw structure. The upper part of the support member 13 protrudes upward from the upper surface 11b of the body member 11. The support member 13 has a valve stem bore 13a extending therethrough in an up-and-down direction (a direction of an axis L). The valve stem bore 13a faces the valve port 15 in the up-and-down direction. The valve stem bore 13a is provided coaxially with the valve port 15. The support member 13 has an internal thread 13c. The internal thread 13c is arranged on the inner peripheral surface of the valve stem bore 13a.

[0025] The can 20 is made of a metal, such as stainless steel. The can 20 has a circular cylindrical shape. The can 20 is open at the lower end and closed at the upper end. The lower end of the can 20 is attached to the upper part of the support element 13 by means of a connecting element 25, which has a circular, plate-like shape.

[0026] In a Fig. In the electric valve 1A shown in Fig. 7, a support member 13A may be mounted in a body member 11A by a press-fitting construction. In the electric valve 1A, the upper part of the body member 11A protrudes upward from an upper surface 12b of a flow channel block 12, and the lower end of a can 20 is fixed to the upper part of the body member 11A.

[0027] The drive mechanism 30 moves the valve element 40 in the up-and-down direction. The drive mechanism 30 includes a magnetic rotor 31, a valve stem 34, and a stator unit 50.

[0028] The magnetic rotor 31 has a circular cylindrical shape. The magnetic rotor 31 is open at the top and closed at the bottom. The outer diameter of the magnetic rotor 31 is smaller than the inner diameter of the can 20. The magnetic rotor 31 has a plurality of north poles (N) and a plurality of south poles (S). The N poles and the S poles are arranged on the outer peripheral surface of the magnetic rotor 31. The N poles and the S poles extend in the up-and-down direction, respectively. The N poles and the S poles are arranged alternately at regular angular intervals in the circumferential direction. The magnetic rotor 31 has, for example, twelve N poles and twelve S poles.

[0029] The valve stem 34 has a circular columnar 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 an external thread 34c. The external thread 34c is arranged on the outer peripheral surface of the valve stem 34. The valve stem 34 is arranged in the valve stem bore 13a, and the external thread 34c is screwed into the internal thread 13c. The internal thread 13c and the external thread 34c form a screw feed mechanism 33. When the valve stem 34 rotates, the valve stem 34 moves up or down depending on the rotation direction.

[0030] The valve element 40 is arranged in the valve chamber 14. The valve element 40 faces the valve port 15 in the up-and-down direction. The valve element 40 is connected to the lower end (the other end) of the valve stem 34. For example, the valve stem 34 and the valve element 40 are integrally formed by cutting a workpiece with a circular column shape.

[0031] The valve element 40 includes a control portion 45 and a seat portion 47. The control portion 45 has a conical shape (a truncated cone shape) with a diameter that gradually decreases toward the valve port 15. The seat portion 47 has a conical shape with a diameter that gradually decreases toward the valve port 15. The cone angle of the control portion 45 is smaller than that of the seat portion 47. The upper end of the control portion 45 is connected to the lower end of the seat portion 47. The outer peripheral surface of the control portion 45 serves as a control surface 46. The outer peripheral surface of the seat portion 47 serves as a seat surface 48. The control surface 46 and the seat surface 48 are outwardly tapered surfaces.

[0032] The valve element 40 is moved in the up and down direction by the drive mechanism 30. The movement of the valve element 40 opens and closes the valve port 15. As shown in Fig. 3, the valve port 15 is closed when the seat surface 48 is in contact with the inner peripheral edge 16a of the valve seat 16. As shown in Fig. As shown in Figure 4, the valve port 15 is open when the seat surface 48 is separated from the inner peripheral edge 16a of the valve seat 16. When the seat surface 48 is separated from the inner peripheral edge 16a, a circular annular gap (a throttle passage) is formed between the inner peripheral edge 16a and the valve element 40. The area of ​​the throttle passage is closely related to the flow rate of fluid flowing through the valve port 15.

[0033] The diagram in Fig. 5 shows the relationship between a valve opening degree and the flow rate in the electric valve 1. The valve opening degree indicates a position of the valve element 40 with respect to the valve seat 16 as a percentage (a measure of movement of the valve element 40 from a position where the valve element 40 is in contact with the valve seat 16). The position of the valve element 40 corresponds to the position of the magnet rotor 31. In the electric valve 1, the magnet rotor 31 is positioned at a reference position Rx when the seat surface 48 is in contact with the inner peripheral edge 16a of the valve seat 16, and the valve opening degree is set to 0% when the magnet rotor 31 is at the reference position Rx.The magnetic rotor 31 is positioned at a fully open position Rz by rotating it by a predetermined angle from the reference position Rx, and the valve opening degree is set to 100% when the magnetic rotor 31 is at the fully open position Rz. The flow rate indicates the flow rate of the fluid flowing through the valve port 15 as a percentage. The flow rate is set to 0% when the magnetic rotor 31 is at the reference position Rx, and the flow rate is set to 100% when the magnetic rotor 31 is at the fully open position Rz.

[0034] When the magnetic rotor 31 rotates in a valve-opening direction, the screw-feeding mechanism 33 moves the valve stem 34 and the valve element 40 upward. When the magnetic rotor 31 rotates in a valve-closing direction, the screw-feeding mechanism 33 moves the valve stem 34 and the valve element 40 downward. When the valve element 40 moves downward and the seat surface 48 comes into contact with the inner peripheral edge 16a of the valve seat 16, the downward movement of the valve element 40 and the valve stem 34 is restricted. When the downward movement of the valve stem 34 is restricted, the external thread 34c is tightly screwed into the internal thread 13c, stopping the screw-feeding mechanism. Therefore, the rotation of the valve stem 34 and the magnetic rotor 31 in the valve-closing direction is restricted by the screw-feeding mechanism 33.

[0035] The stator unit 50 includes a stator 60 and a housing 70.

[0036] The stator 60 has a circular cylindrical shape. The stator 60 includes an A-phase stator 61, a B-phase stator 62, and a resin molded element 63.

[0037] The A-phase stator 61 includes a plurality of claw-pole type pole teeth 61a and 61b in the inner circumference. The tip ends of the pole teeth 61a face downward, and the tip ends of the pole teeth 61b face upward. The pole teeth 61a and the pole teeth 61b are alternately arranged at regular angular intervals in the circumferential direction. For example, the A-phase stator 61 has twelve pole teeth 61a and twelve pole teeth 61b. The angle between the adjacent pole teeth 61a and 61b is 15 degrees. When a coil 61c of the A-phase stator 61 is energized, the pole teeth 61a and the pole teeth 61b have opposite polarities.

[0038] The B-phase stator 62 includes a plurality of claw-pole type pole teeth 62a and 62b in the inner circumference. The tip ends of the pole teeth 62a face downward, and the tip ends of the pole teeth 62b face upward. The pole teeth 62a and the pole teeth 62b are alternately arranged at regular angular intervals in the circumferential direction. For example, the B-phase stator 62 has twelve pole teeth 62a and twelve pole teeth 62b. The angle between the adjacent pole teeth 62a and 62b is 15 degrees. When a coil 62c of the B-phase stator 62 is energized, the pole teeth 62a and the pole teeth 62b have opposite polarities.

[0039] The A-phase stator 61 is arranged coaxially with the B-phase stator 62. The A-phase stator 61 is in contact with the B-phase stator 62. Viewed in the direction of the axis L, the angle between the pole tooth 61a of the A-phase stator 61 and the pole tooth 62a of the B-phase stator 62, which are adjacent to each other, is 7.5 degrees.

[0040] The molded element 63 fills the A-phase stator 61 and the B-phase stator 62. The molded element 63, together with the pole teeth 61a and 61b and the pole teeth 62a and 62b, forms an inner peripheral surface 60a. The diameter of the inner peripheral surface 60a of the stator is equal to that of the outer peripheral surface of the can 20. The molded element 63 includes a terminal support portion 64.

[0041] The terminal support portion 64 extends in a lateral direction (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 terminals 65. The terminals 65 extend in the lateral direction from the tip end of the terminal support portion 64. The terminals 65 are connected to the coil 61c of the A-phase stator 61 and the coil 62c of the B-phase stator 62.

[0042] In the electric valve 1, the respective center axes of the body member 11 (the valve port 15 and the valve seat 16), the support member 13 (the valve stem bore 13a), the can 20, the magnet rotor 31, the valve stem 34, the valve element 40 (the control portion 45 and the seat portion 47), and the stator 60 (the A-phase stator 61 and the B-phase stator 62) are aligned with the axis L.

[0043] The can 20 is arranged within the stator 60. The magnetic rotor 31 is arranged within the can 20. The magnetic rotor 31 and the stator 60 are elements of a stepper motor 66.

[0044] In the electric valve 1, when the seat surface 48 is in contact with the inner peripheral edge 16a of the valve seat 16, the magnetic rotor 31 is located at the reference position Rx. When the magnetic rotor 31 is located at the reference position Rx, inputting a maximum number z of pulses to the stepping motor 66 moves the magnetic rotor 31 from the reference position Rx to the fully open position Rz. The maximum number z is predetermined and set to 500 in the embodiment. The step angle of the stepping motor 66 is 3.75 degrees. In this specification, "inputting pulses to the stepping motor 66" is synonymous with "supplying the stator 60 of the stepping motor 66 with drive currents corresponding to the pulses."

[0045] In the electric valve 1, the position of the magnetic rotor 31 corresponds to the number of pulses input to the stepping motor 66. Specifically, the respective positions are assigned the numbers 0 to z, which are obtained by dividing the rotation angle from the reference position Rx to the fully open position Rz by the maximum number z. In the embodiment, the positions are represented as positions [0] to

[500] .

[0046] The housing 70 is made of synthetic resin. The housing 70 houses the stator 60 and the controller 80. The housing 70 includes a peripheral wall portion 71, a top wall portion 72, and a connector 73.

[0047] The peripheral wall portion 71 has a circular cylindrical shape. The stator 60 is embedded in the peripheral wall portion 71. The diameter of an inner peripheral surface 71a of the peripheral wall portion 71 is equal to that of the inner peripheral surface 60a of the stator. The inner peripheral surface 71a is flush and continuous with the inner peripheral surface 60a of the stator. 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 arranged in the upper part of the housing 70. The inner peripheral surface 71a of the peripheral wall portion 71, an inner surface 72a of the upper wall portion 72, and the inner peripheral surface 60a of the stator define an interior space 74 of the stator unit 50. The can 20 is arranged in the interior space 74.

[0048] The housing 70 has a circuit board compartment 75. The circuit board compartment 75 is located adjacent to the interior space 74. A partition wall 76 is arranged between the interior space 74 and the circuit board compartment 75. The partition wall 76 separates the interior space 74 from the circuit board compartment 75. The housing 70 has an opening 70a that communicates with the circuit board compartment 75, and the opening 70a is closed by a cover element 77.

[0049] The controller 80 is arranged in the circuit board compartment 75 of the housing 70. The controller 80 includes a main circuit board 90, a sub-circuit board 100, a magnetic sensor 110, and a microcomputer 120.

[0050] The main circuit board 90 is a circuit board on which electronic components are mounted. The main circuit board 90 is housed in the circuit board compartment 75. The main circuit board 90 is arranged parallel to the up-and-down direction. The microcomputer 120 is mounted on the main circuit board 90. The terminals 65 of the stator 60 are connected to the main circuit board 90.

[0051] The sub-circuit board 100 is a circuit board on which electronic components are mounted. The sub-circuit board 100 is housed in the circuit board compartment 75. The sub-circuit board 100 is arranged perpendicular to the main circuit board 90. A first end 100a of the sub-circuit board 100 is arranged near the main circuit board 90. A second end 100b of the sub-circuit board 100 is arranged near the partition wall 76. The sub-circuit board 100 is connected to the main circuit board 90 via a circuit board connector.

[0052] The magnetic sensor 110 is, for example, a Hall IC. The magnetic sensor 110 is arranged at the second end 100b of the sub-circuit board 100. The magnetic sensor 110 and the magnetic rotor 31 are arranged laterally, with the can 20 and the partition wall 76 therebetween. The magnetic sensor 110 outputs a signal (ON signal / OFF signal) corresponding to the direction of the magnetic field generated by the magnetic rotor 31. The electric valve 1 may include a permanent magnet that rotates together with the magnetic rotor 31, and the magnetic sensor 110 may output a signal corresponding to the direction of the magnetic field generated by the permanent magnet.

[0053] For example, the microcomputer 120 is a microcomputer for embedded devices in which a central processing unit, a non-volatile memory, a random access memory, a communication module, a motor driver, etc., are integrated into one package. The microcomputer 120 controls the electric valve 1. A non-volatile memory, a random access memory, a communication module, and a motor driver may be separate electronic components externally connected to the microcomputer 120.

[0054] As in Fig. 6, the controller 80 includes a storage unit 210, a communication unit 220, and a rotation control unit 230. The non-volatile memory serves as the storage unit 210. The central processing unit executes a program stored in the non-volatile memory and functions as the communication unit 220 and the rotation control unit 230. The working memory stores controlled variables used by the rotation control unit 230. The communication module is connected to the air conditioner control unit 400 via a cable (not shown) connected to the 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 the drive currents corresponding to the pulses to the coil 61c and the coil 62c.

[0055] The storage unit 210 stores, for example, a current position Rc of the magnet rotor 31 immediately before the electric valve 1 is turned off. When the electric valve 1 is in operation, the current position Rc is stored in the working memory.

[0056] The communication unit 220 communicates with the control unit 400 via the communication module. The communication unit 220 receives various commands from the control unit 400 and transmits them to the rotary control unit 230. The communication unit 220 receives the state of the electric valve 1 from the rotary control unit 230 and transmits it to the control unit 400.

[0057] The communication unit 220 receives a valve element movement command from the control unit 400. The valve element movement command includes information regarding a target position Rt of the magnetic rotor 31. The information indicates a desired valve opening degree. The information may indicate a rotation angle relative to the current position Rc of the magnetic rotor 31 (specifically, the number of pulses to be input to the stepper motor 66 and the rotation direction of the magnetic rotor 31). The rotation control unit 230 obtains the target position Rt of the magnetic rotor 31 based on the information.

[0058] In the electric valve 1, 0 [%] to 100 [%] of the valve opening degree correspond to the positions [0] to

[500] of the magnetic rotor 31. The position [0] is the reference position Rx, and the position

[500] is the fully open position Rz. For example, when the valve opening degree included in the valve element movement command indicates 0%, the target position Rt is position [0]. When the valve opening degree included in the valve element movement command indicates 25%, the target position Rt is position

[125] . When the valve opening degree included in the valve element movement command indicates 50%, the target position Rt is position

[250] . When the valve opening degree included in the valve element movement command indicates 75%, the target position Rt is position

[375] . If the valve opening degree included in the valve element movement command indicates 100%, the target position Rt is position

[500] .

[0059] When the communication unit 220 receives the valve element movement command, the rotation control unit 230 obtains the position of the magnetic rotor 31 corresponding to the valve opening degree included in the valve element movement command as the target position Rt. For example, the rotation control unit 230 obtains the position

[100] as the target position Rt when the valve opening degree indicates 20 [%], obtains the position

[400] as the target position Rt when the valve opening degree indicates 80 [%], and obtains the position

[500] as the target position Rt when the valve opening degree indicates 100 [%].

[0060] When the number of the position serving as the target position Rt of the magnetic rotor 31 is larger than the number of the position serving as the current position Rc, the rotation control unit 230 inputs pulses, the number of which is obtained by subtracting the number of the position serving as the current position Rc from the number of the position serving as the target position Rt, to the stepping motor 66 to rotate the magnetic rotor 31 in the valve opening direction.

[0061] When the number of the position serving as the target position Rt of the magnet rotor 31 is smaller than the number of the position serving as the current position Rc, the rotation control unit 230 inputs pulses, the number of which is obtained by subtracting the number of the position serving as the target position Rt from the number of the position serving as the current position Rc, to the stepping motor 66 to rotate the magnet rotor 31 in the valve closing direction.

[0062] The rotation control unit 230 obtains the rotation angle of the magnetic rotor 31 based on the signal output from the magnetic sensor 110 and determines the state (a rotation state / a non-rotation state) of the magnetic rotor 31. When the magnetic rotor 31 is rotating, the magnetic sensor 110 alternately outputs ON and OFF signals. When the magnetic rotor 31 is not rotating, the magnetic sensor 110 continuously outputs ON or OFF signals. The controller 80 detects the rotation angle of the magnetic rotor 31 based on the number of ON and OFF signal changes. When a change in the signal (ON and OFF signal changes) is detected, the controller 80 determines that "the rotation state" in which the magnetic rotor 31 is rotating is indicated. When the change in the signal is not detected, the controller 80 determines that "the non-rotation state" in which the magnetic rotor 31 is not rotating is indicated.When the rotation control unit 230 rotates the magnet rotor 31 in the valve closing direction and determines that the non-rotation state is indicated, the rotation control unit 230 detects that the rotation of the magnet rotor 31 in the valve closing direction is restricted.

[0063] The rotation control unit 230 determines whether the valve element movement command was successful or failed. Specifically, the rotation control unit 230 obtains a rotation angle (a calculated rotation angle) of the magnetic rotor 31 by multiplying the number of pulses input to the stepper motor 66 by the step angle and a rotation angle (a measured rotation angle) of the magnetic rotor 31 based on the signal from the magnetic sensor 110. The rotation control unit 230 compares the calculated rotation angle with the measured rotation angle. If the calculated rotation angle matches the measured rotation angle, the rotation control unit 230 transmits information as a command result to the control unit 400 via the communication unit 220, and the information indicates that the valve element movement command was successful.If the calculated rotation angle does not match the measured rotation angle, the rotation control unit 230 transmits information as a command result to the control unit 400 via the communication unit 220, and the information indicates that the command to move the valve element failed.

[0064] An operating example of the solenoid valve 1 is described below.

[0065] When the control 80 is switched on, the control 80 of the solenoid valve 1 goes into a start mode.

[0066] In the startup mode, the controller 80 copies the current position Rc from the storage unit 210 to the working memory if the current position Rc of the magnetic rotor 31 is stored in the storage unit 210, and then enters a normal operation mode. In the normal operation mode, the controller 80 waits for a command transmitted from the control unit 400.

[0067] In the start mode, the controller 80 enters an initialization operation mode when the current position Rc is not stored in the storage unit 210. Alternatively, the controller 80 enters the initialization operation mode when the controller 80 receives an initialization command from the control unit 400 in the normal operation mode.

[0068] In the initialization operation mode, the controller 80 inputs pulses to the stepping motor 66 to rotate the magnetic rotor 31 in the valve-closing direction. The controller 80 determines that the rotation state is indicated when the change in the signal from the magnetic sensor 110 is detected. The controller 80 determines that the non-rotation state is indicated when the change in the signal from the magnetic sensor 110 is not detected. When the controller 80 determines that the non-rotation state is indicated, the controller 80 detects that the rotation of the magnetic rotor 31 in the valve-closing direction is restricted. The controller 80 stores the position [0], which is the reference position Rx, as the current position Rc in the working memory and enters the normal operation mode.

[0069] In the normal operation mode, when the controller 80 receives the valve element movement command from the control unit 400, the controller 80 rotates the magnet rotor 31 to move the valve element 40 and achieve the valve opening degree included in the valve element movement command.

[0070] For example, if the current position Rc is position [0] and the valve opening degree included in the valve element movement command indicates 80%, the controller 80 obtains the position

[400] as the target position Rt. The controller 80 inputs 400 (400 = 400 - 0) pulses to the stepping motor 66 to rotate the magnetic rotor 31 in the valve opening direction. This causes the screw feed mechanism 33 to move the valve stem 34 and the magnetic rotor 31 upward, separating the valve element 40 from the valve seat 16 and positioning the valve element 40 at a position corresponding to position

[400] (80% valve opening degree). When the controller 80 finishes inputting pulses to the stepping motor 66, the controller 80 stores the position

[400] in the working memory as the current position Rc.The controller 80 determines whether the command to move the valve element was successful or failed and transmits the command result to the control unit 400. The controller 80 then waits for the next command transmitted from the control unit 400.

[0071] For example, if the current position Rc is position

[400] and the valve opening degree included in the valve element movement command indicates 30%, the controller 80 obtains position

[150] as the target position Rt. The controller 80 inputs 250 (250 = 400 - 150) pulses to the stepping motor 66 to rotate the magnet rotor 31 in the valve closing direction. This causes the screw feed mechanism 33 to move the valve stem 34 and the magnet rotor 31 downward, moving the valve element 40 toward the valve seat 16 and positioning the valve element 40 at a position corresponding to position

[150] (30% valve opening degree). When the controller 80 finishes inputting pulses to the stepping motor 66, the controller 80 stores position

[150] in the working memory as the current position Rc.The controller 80 determines whether the command to move the valve element was successful or failed and transmits the command result to the control unit 400. The controller 80 then waits for the next command transmitted from the control unit 400.

[0072] For example, if the current position Rc is position

[150] and the valve opening degree included in the valve element movement command indicates 100%, the controller 80 obtains position

[500] as the target position Rt. The controller 80 inputs 350 (350 = 500 - 150) pulses to the stepping motor 66 to rotate the magnet rotor 31 in the valve opening direction. This causes the screw feed mechanism 33 to move the valve stem 34 and the magnet rotor 31 upward, moving the valve element 40 away from the valve seat 16 and positioning the valve element 40 at a position corresponding to position

[500] (100% valve opening degree). When the controller 80 finishes inputting pulses to the stepping motor 66, the controller 80 stores position

[500] in the working memory as the current position Rc.The controller 80 determines whether the command to move the valve element was successful or failed and transmits the command result to the control unit 400. The controller 80 then waits for the next command transmitted from the control unit 400.

[0073] For example, if the current position Rc is position

[500] and the valve opening degree included in the valve element movement command indicates 0%, the controller 80 obtains position [0] as the target position Rt. The controller 80 inputs 500 (500 = 500 - 0) pulses to the stepping motor 66 to rotate the magnet rotor 31 in the valve closing direction. This causes the screw feed mechanism 33 to move the valve stem 34 and the magnet rotor 31 downward, bringing the valve element 40 into contact with the valve seat 16 and positioning the valve element 40 at a position corresponding to position [0] (0% valve opening degree). When the controller 80 finishes inputting pulses to the stepping motor 66, the controller 80 stores position [0] in the working memory as the current position Rc.The controller 80 determines whether the command to move the valve element was successful or failed and transmits the command result to the control unit 400. The controller 80 then waits for the next command transmitted from the control unit 400.

[0074] If the valve opening degree included in the command to move the valve element indicates less than 0% (i.e., a negative value) or more than 100%, the controller 80 transmits a command result to the control unit 400 indicating receipt of an impermissible valve opening degree. The controller 80 then waits for the next command transmitted from the control unit 400.

[0075] When the controller 80 receives a power-off command from the control unit 400, the controller 80 copies the current position Rc from the working memory to the storage unit 210 and prepares for power-off.

[0076] The electric valve 1 includes the valve body 10, which has the valve port 15 and the valve seat 16 surrounding the valve port 15, the valve element 40 facing the valve port 15, the valve stem 34, and the stepping motor 66. The valve stem 34 has the external thread 34c. The valve body 10 has the valve stem bore 13a arranged coaxially with the valve port 15. The internal thread 13c, into which the external thread 34c is screwed, is provided on the inner peripheral surface of the valve stem bore 13a. The external thread 34c and the internal thread 13c constitute the screw feed mechanism 33. The upper end of the valve stem 34 is coaxially fixed to the magnetic rotor 31 of the stepping motor 66. The lower end (one 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 element 40 comes into contact with the valve seat 16, the valve seat 16 restricts the movement of the valve element 40 toward the valve port 15.

[0077] In this configuration, the screw feed mechanism 33 moves the valve stem 34 and the valve element 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 element 40 comes into contact with the valve seat 16, the movement of the valve element 40 toward the valve port 15 is restricted, stopping the movement of the valve element 40 and the valve stem 34. The external thread 34c is tightly screwed into the internal thread 13c, stopping the screw feed mechanism 33. Therefore, the rotation of the valve stem 34 in the valve-closing direction is restricted by the screw feed mechanism 33, stopping the rotation of the magnetic rotor 31. As a result, a stopper to be provided on the magnetic rotor 31 can be omitted, and the rotation of the magnetic rotor 31 can be stopped when the valve element 40 stops moving.

[0078] The electric valve 1 includes the controller 80 for controlling the stepping motor 66. In the initialization operation mode, the controller 80 rotates the magnetic rotor 31 in the valve-closing direction and obtains the position of the magnetic rotor 31 when the rotation of the magnetic rotor 31 in the valve-closing direction is restricted as the reference position Rx. In the normal operation mode, the controller 80 positions the magnetic rotor 31 based on the reference position Rx. In the normal operation mode, the controller 80 does not rotate the magnetic rotor 31 beyond the reference position Rx in the valve-closing direction or beyond the fully open position Rz in the valve-opening direction. The controller 80 controls the position of the magnetic rotor 31 using the rotation angle (the number of pulses input to the stepping motor 66) from the reference position Rx.

[0079] With this configuration, the controller 80 can stop the rotation of the magnet rotor 31 when the magnet rotor 31 is rotated in the valve-closing direction and reaches the reference position Rx. Therefore, the rotation of the magnet rotor 31 in the valve-closing direction beyond the reference position Rx can be suppressed, which reduces wear on the valve seat 16 and power consumption. The controller 80 can stop the rotation of the magnet rotor 31 when the magnet rotor 31 is rotated in the valve-opening direction and reaches the fully open position Rz. Therefore, the rotation of the magnet rotor 31 in the valve-opening direction beyond the fully open position Rz can be suppressed, which prevents the external thread 34c and the internal thread 13c from being unscrewed.As a result, a stopper for restricting the rotation of the magnet rotor 31 in the valve opening direction can be omitted, and a coil spring for returning the external thread 34c and the internal thread 13c to the screwed position can be omitted.

[0080] The controller 80 includes the magnetic sensor 110, which outputs the signal corresponding to the rotation of the magnetic rotor 31. The controller 80 detects that the rotation of the magnetic rotor 31 in the valve-closing direction is restricted based on the signal output from the magnetic sensor 110. As a result, it is possible to detect whether the rotation of the magnetic rotor 31 in the valve-closing direction is restricted with a relatively simple configuration. The controller 80 can detect that the rotation of the magnetic rotor 31 in the valve-closing direction is restricted based on the counter electromotive voltage generated in the stator 60 when the rotation of the magnetic rotor 31 is restricted. (SECOND EMBODIMENT)

[0081] An electric valve 2 according to a second embodiment of the present invention will be described below with reference to Fig. 8 described. Fig. 8 is a sectional view of an electric valve according to the second embodiment of the present invention.

[0082] As in Fig. 8, the electric valve 2 includes a valve body 10B, a can 20, a drive mechanism 30B, a valve element 40B, and a controller 80. In the following description, elements having the same (including substantially the same) configurations as those of the electric valve 1 are denoted by the same reference numerals as those of the electric valve 1, and detailed descriptions of these elements are omitted.

[0083] The valve body 10B is made of a metal, such as an aluminum alloy. The valve body 10B includes a body member 11, a flow channel block 12, and a support member 13B.

[0084] The support member 13B includes a first support portion 131 and a second support portion 132. The first support portion 131 has a circular cylindrical shape. The first support portion 131 is disposed in a first mounting hole 11a. The first support portion 131 is mounted in the 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 stem bore 132a extending therethrough in an up-and-down direction. The valve stem bore 132a faces an upper end surface 40b (an end surface) of the valve element 40B in the up-and-down direction. The valve stem bore 132a is arranged coaxially with a valve port 15. The second support portion 132 has an internal thread 132c. The internal thread 132c is arranged on the inner peripheral surface of the valve stem bore 132a.

[0085] The drive mechanism 30B moves the valve element 40B in the up-and-down direction. The drive mechanism 30B includes a magnetic rotor 31B, a valve stem 34B, and a stator unit 50.

[0086] The magnetic rotor 31B has a circular cylindrical shape. A wall portion 31d is provided within the magnetic rotor 31B. The wall portion 31d is arranged at the center of the magnetic rotor 31B in the up-and-down direction. The magnetic rotor 31B and a stator 60 are elements of a stepping motor 66B.

[0087] The valve stem 34B has a circular columnar 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 an external thread 34c. The external thread 34c is arranged on the outer peripheral surface of the valve stem 34B. The valve stem 34B is arranged in the valve stem bore 132a, and the external thread 34c is screwed into the internal thread 132c. The internal thread 132c and the external thread 34c form a screw feed mechanism 33B. When the valve stem 34B rotates, the valve stem 34B moves up or down depending on the rotation direction.

[0088] The valve element 40B has a circular columnar shape. The valve element 40B is supported by the first support portion 131 and is movable in the up-and-down direction. The upper part of the valve element 40B is disposed within the first support portion 131, and the lower part is disposed in a valve chamber 14. The valve element 40B faces the valve port 15 in the up-and-down direction. A control portion 45 and a seat portion 47 are provided in the lower part of the valve element 40B. The valve element 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 element 40B. A spring receiving portion 49, which has a flange shape and protrudes radially outward, is provided in the upper end of the valve element 40B. A valve opening spring 37 is arranged between the spring receiving portion 49 and the first support portion 131.The valve opening spring 37 is a compression coil spring and pushes the valve element 40B upwards.

[0089] When the magnetic rotor 31B rotates in a valve-opening direction, the screw-feeding mechanism 33B moves the valve stem 34B upward, and the valve-opening spring 37 pushes and moves the valve element 40B upward. When the magnetic rotor 31B rotates in a valve-closing direction, the screw-feeding mechanism 33B moves the valve stem 34B downward, and the valve stem 34B pushes and moves the valve element 40B downward. When the valve element 40B moves downward and a seat surface 48 comes into contact with an inner peripheral edge 16a of the valve seat 16, the valve element 40B and the valve stem 34B are restricted from moving downward. Therefore, the rotation of the valve stem 34B and the magnetic rotor 31B in the valve-closing direction is restricted by the screw-feeding mechanism 33B.

[0090] The electric valve 2 includes the valve body 10B, which has the valve port 15 and the valve seat 16 surrounding the valve port 15, the valve element 40B facing the valve port 15, the valve stem 34B, and the stepping motor 66B. The valve stem 34B has the external thread 34c. The valve body 10B has the valve stem bore 132a arranged coaxially with the valve port 15. The internal thread 132c, into which the external thread 34c is screwed, is provided on the inner peripheral surface of the valve stem bore 132a. The external thread 34c and the internal thread 132c constitute the screw feed mechanism 33B. The upper end of the valve stem 34B is coaxially fixed to the magnetic rotor 31B of the stepping motor 66B. The lower end (one end) of the valve stem 34B is in contact with the valve element 40B and is connected to the valve element 40B.When the magnet rotor 31B rotates in the valve closing direction, the valve stem 34B pushes the valve element 40B toward the valve port 15, and the valve element 40B moves toward the valve port 15. When the valve element 40B comes into contact with the valve seat 16, the valve seat 16 restricts the movement of the valve element 40B toward the valve port 15.

[0091] In this configuration, the screw feed mechanism 33B moves the valve stem 34B and the valve element 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 element 40B comes into contact with the valve seat 16, the movement of the valve element 40B toward the valve port 15 is restricted, stopping the movement of the valve element 40B and the valve stem 34B. The external thread 34c is tightly screwed into the internal thread 132c, stopping the screw feed mechanism 33B. Therefore, the rotation of the valve stem 34B in the valve closing direction is restricted by the screw feed mechanism 33B, stopping the rotation of the magnetic rotor 31B. As a result, a stopper to be provided on the magnet rotor 31B can be omitted, and the rotation of the magnet rotor 31B can be stopped when the valve element 40B stops moving.

[0092] The electric valve 2 has the same (including substantially the same) functions and effects as those of the electric valve 1. (THIRD EMBODIMENT)

[0093] An electric valve 3 according to a third embodiment of the present invention will be described below with reference to Fig. 9 described. Fig. 9 is a sectional view of an electric valve according to the third embodiment of the present invention.

[0094] As in Fig.9, the electric valve 3 includes a valve body 10C, a can 20, a drive mechanism 30C, a valve element 40C, and a controller 80. In the following description, elements having the same (including substantially the same) configurations as those of the electric valve 1 are denoted by the same reference numerals as those of the electric valve 1, and detailed descriptions of these elements are omitted.

[0095] The valve body 10C is made of a metal, such as an aluminum alloy. The valve body 10C includes a body member 11, a flow channel block 12, a support member 13C, and a bearing 19C.

[0096] The support element 13C has a circular cylindrical shape. The support element 13C is arranged in a first mounting hole 11a. The support element 13C is mounted in the body element 11 by a screw construction. The upper part of the support element 13C protrudes upward from an upper surface 11b of the body element 11.

[0097] The bearing 19C is a ball bearing. The bearing 19C is coaxially mounted in the upper part of the support element 13C. The bearing 19C is arranged coaxially with a valve port 15. The bearing 19C rotatably supports a valve stem 34C.

[0098] The drive mechanism 30C moves the valve element 40C in an up-and-down direction. The drive mechanism 30C includes a magnetic rotor 31C, the valve stem 34C, and a stator unit 50.

[0099] The magnetic rotor 31C has a circular cylindrical shape. A wall portion 31e is provided within the magnetic rotor 31C. The wall portion 31e is located near the lower end of the magnetic rotor 31C. The magnetic rotor 31C and a stator 60 are elements of a stepper motor 66C.

[0100] The valve stem 34C has a circular columnar shape. The upper end of the valve stem 34C is coaxially attached to the wall portion 31e of the magnet rotor 31C via a coupling element 34e. The valve stem 34C has an external thread 34c. The external thread 34c is arranged on the outer peripheral surface of the valve stem 34C.

[0101] The valve element 40C has a circular columnar shape. The valve element 40C is supported by the support member 13C and is movable in the up-and-down direction. The rotation of the valve element 40C around the central axis is restricted. The upper part of the valve element 40C is disposed within the support member 13C, and the lower part is disposed in a valve chamber 14. The valve element 40C faces the valve port 15 in the up-and-down direction. The valve element 40C has a valve stem bore 40a. The valve stem bore 40a is provided on an upper end surface 40b of the valve element 40C. The valve element 40C has an internal thread 40c. The internal thread 40c is disposed on the inner peripheral surface of the valve stem bore 40a. A control portion 45 and a seat portion 47 are provided in the lower part of the valve element 40C. The valve element 40C is connected to the lower end of the valve stem 34C.Specifically, the valve stem 34C is disposed in the valve stem bore 40a, and the external thread 34c is screwed into the internal thread 40c. The internal thread 40c and the external thread 34c form a screw feed mechanism 33C. The screw feed mechanism 33C connects the valve stem 34C and the valve element 40C. When the valve stem 34C rotates, the valve element 40C moves up or down according to the rotation direction of the valve stem 34C. The valve stem 34C does not move up or down.

[0102] When the magnetic rotor 31C rotates in a valve-opening direction, the valve stem 34C also rotates in the valve-opening direction, and the screw-feeding mechanism 33C moves the valve element 40C upward. When the magnetic rotor 31C rotates in a valve-closing direction, the valve stem 34C also rotates in the valve-closing direction, and the screw-feeding mechanism 33C moves the valve element 40C downward. When the valve element 40C moves downward and a seat surface 48 comes into contact with an inner peripheral edge 16a of a valve seat 16, the downward movement of the valve element 40C is restricted. Therefore, the rotation of the valve stem 34C and the magnetic rotor 31C in the valve-closing direction is restricted by the screw-feeding mechanism 33C.

[0103] The electric valve 3 includes the valve body 10C, which has the valve port 15 and the valve seat 16 surrounding the valve port 15, the valve element 40C facing the valve port 15, the valve stem 34C, and the stepping motor 66C. The valve body 10C includes the bearing 19C that rotatably supports the valve stem 34C. The bearing 19C is arranged coaxially with the valve port 15. The valve stem 34C has the external thread 34c. The valve element 40C has the valve stem bore 40a. The internal thread 40c, into which the external thread 34c is screwed, is provided on the inner peripheral surface of the valve stem bore 40a. The external thread 34c and the internal thread 40c constitute the screw feed mechanism 33C. The upper end of the valve stem 34C is coaxially fixed to the magnetic rotor 31C of the stepping motor 66C. The lower end (one end) of the valve stem 34C is connected to the valve element 40C.When the magnet rotor 31C rotates in the valve closing direction, the valve element 40C moves toward the valve port 15. When the valve element 40C comes into contact with the valve seat 16, the valve seat 16 restricts the movement of the valve element 40C toward the valve port 15.

[0104] In this configuration, the screw feed mechanism 33C moves the valve element 40C. When the magnetic rotor 31C rotates in the valve-closing direction, the valve stem 34C also rotates in the valve-closing direction. When the valve element 40C comes into contact with the valve seat 16, the movement of the valve element 40C toward the valve port 15 is restricted, stopping the movement of the valve element 40C. The external thread 34c is tightly screwed into the internal thread 40c, stopping the screw feed mechanism 33C. Therefore, the rotation of the valve stem 34C in the valve-closing direction is restricted by the screw feed mechanism 33C, stopping the rotation of the magnetic rotor 31C. As a result, a stopper to be provided on the magnetic rotor 31C can be omitted, and the rotation of the magnetic rotor 31C can be stopped when the valve element 40C stops moving.

[0105] The electric valve 3 has the same (including substantially the same) functions and effects as those of the electric valve 1.

[0106] In the electric valves 1 to 3 described above, the valve stem has the external thread, the valve body or the valve element has the internal thread into which the external thread is screwed, and the external and internal threads form the screw feed mechanism. In an electric valve according to the present invention, a valve stem may have an internal thread, a valve body or a valve element may have an external thread screwed into the internal thread, and the external and internal threads may form a screw feed mechanism. In other words, it is sufficient that the electric valve according to the present invention has a configuration in which a valve stem and a valve body form a screw feed mechanism, or a valve stem and a valve element form a screw feed mechanism.

[0107] In this specification, terms indicating shapes, such as "circular-cylindrical" and "circular-columnar," are also used to refer to elements and portions of the elements that substantially have the shapes indicated by the terms. For example, "circular-cylindrical element" includes a circular-cylindrical element and a substantially circular-cylindrical element.

[0108] The embodiments of the present invention are described above. However, the present invention is not limited to these embodiments. Embodiments obtained by a person skilled in the art by appropriately adding, removing, or modifying components according to the above-described embodiments, and an embodiment obtained by appropriately combining features of the embodiments, fall within the scope of the present invention without departing from the spirit of the present invention. List of Reference Symbols (First Embodiment)

[0109] 1, 1A ... electric valve, 10 ... valve body, 11, 11A ... body member, 11a ... first mounting hole, 11b ... top surface, 12 ... flow channel block, 12a ... second mounting hole, 12b ... top surface, 13, 13A ... support member, 13a ... valve stem hole, 13c ... internal thread, 14 ... valve chamber, 15 ... valve port, 15a ... top end, 16 ... valve seat, 16a ... inner peripheral edge, 17 ... flow channel, 18 ... flow channel, 20 ... can, 25 ... connecting member, 30 ... drive mechanism, 31 ... magnet rotor, 31d ... wall portion, 31e ... wall portion, 33 ... screw feed mechanism, 34 ... valve stem, 34c ... external thread, 34e ... coupling member, 40 ... valve element, 45 ... control section, 46 ... control surface, 47 ... seat section, 48 ... seat surface, 50 ... stator unit, 60 ... stator, 60a ... inner peripheral surface of the stator, 61 ... A-phase stator, 61a ... pole tooth, 61b ... pole tooth, 61c ... coil, 62 ... B-phase stator, 62a ... pole tooth, 62b ... Pole tooth, 62c ... coil, 63 ... mold member, 64 ... terminal support portion, 65 ... terminal, 66 ... stepping motor, 70 ... casing, 70a ... opening, 71 ... peripheral wall portion, 71a ... inner peripheral surface, 72 ... upper wall portion, 72a ... inner surface, 73 ... connector, 74 ... inner space, 75 ... circuit board space, 76 ... partition wall, 77 ... cover member, 80 ... controller, 90 ... main circuit board, 100 ... sub circuit 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 EMBODIMENT)

[0110] 2 ... electric valve, 10B ... valve body, 13B ... support member, 30B ... drive mechanism, 31B ... magnetic rotor, 33B ... screw feed mechanism, 34B ... valve stem, 37 ... valve opening spring, 40B ... valve element, 40b ... upper end face, 49 ... spring receiving portion, 66B ... stepping motor, 131 ... first support portion, 132 ... second support portion, 132a ... valve stem bore, 132c ... internal thread (THIRD EMBODIMENT)

[0111] 3 ... electric valve, 10C ... valve body, 13C ... support element, 19C ... bearing, 30C ... drive mechanism, 31C ... magnetic rotor, 33C ... screw feed mechanism, 34C ... valve stem, 40C ... valve element, 40a ... valve stem bore, 40b ... upper end face, 40c ... internal thread, 66C ... stepper motor QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2018-179133

[0002]

Claims

[1] 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; and a stepper motor, wherein the valve stem and the valve body form a screw feed mechanism or the valve stem and the valve element form a screw feed mechanism, wherein the valve stem is coaxially attached to a magnetic rotor of the stepper motor, wherein one end of the valve stem is connected to the valve element, wherein the valve element moves toward the valve port when the magnet rotor rotates in a valve closing direction, and wherein the valve seat restricts the movement of the valve element towards the valve port when the valve element comes into contact with the valve seat. [2] Electric valve according to claim 1, wherein the valve stem and the valve body form the screw feed mechanism, and wherein the valve stem has an external thread, the valve body has an internal thread into which the external thread is screwed, and the external thread and the internal thread form the screw feed mechanism. [3] Electric valve according to claim 1, wherein the valve stem and the valve element form the screw feed mechanism, and wherein the valve stem has an external thread, the valve element has an internal thread into which the external thread is screwed, and the external thread and the internal thread form the screw feed mechanism. [4] Electric valve according to claim 1, wherein the valve stem and the valve body form the screw feed mechanism, and wherein the valve stem has an internal thread, the valve body has an external thread which is screwed into the internal thread, and the external thread and the internal thread form the screw feed mechanism. [5] Electric valve according to claim 1, wherein the valve stem and the valve element form the screw feed mechanism, and wherein the valve stem has an internal thread, the valve element has an external thread screwed into the internal thread, and the external thread and the internal thread form the screw feed mechanism. [6] Electric valve according to claim 2, wherein the valve body has a valve stem bore arranged coaxially with the valve port, wherein the internal thread is provided on an inner peripheral surface of the valve stem bore and wherein the end of the valve stem is integrally connected to the valve element. [7] Electric valve according to claim 2, wherein the valve body has a valve stem bore arranged coaxially with the valve port, wherein the internal thread is provided on an inner peripheral surface of the valve stem bore, wherein the end of the valve stem is in contact with the valve element and wherein the valve stem pushes the valve element toward the valve port when the magnet rotor rotates in the valve closing direction. [8] Electric valve according to claim 3, wherein the valve body has a bearing which rotatably supports the valve stem, wherein the bearing is arranged coaxially to the valve connection, wherein the valve element has a valve stem bore and wherein the internal thread is provided on an inner peripheral surface of the valve stem bore. [9] Electric valve according to one of claims 1 to 8, wherein the electric valve includes a controller for controlling the stepper motor, wherein in an initialization operation mode, the controller rotates the magnet rotor in the valve closing direction and obtains as a reference position a position of the magnet rotor when the rotation of the magnet rotor in the valve closing direction is restricted, and wherein in a normal operating mode, the controller positions the magnet rotor based on the reference position. [10] Electric valve according to claim 9, wherein the controller includes a magnetic sensor that outputs a signal corresponding to the rotation of the magnetic rotor, and wherein the controller detects that the rotation of the magnet rotor in the valve closing direction is restricted based on the signal output from the magnetic sensor.

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