Electric valve control device, electric valve device, and load detection method for electric valve

Abstract

[Problem] To provide an electric valve control device, an electric valve device, and a load detection method for the electric valve, which are capable of detecting a load on a rotor of a stepping motor with a relatively simple configuration. [Solution] An electric valve device 1 comprises an electric valve 5 and an electric valve control device 70. The electric valve 5 includes: a valve body 10 having a valve port 13; a stepping motor 66 having a rotor 41 and a coil to which a drive current for rotating the rotor 41 is supplied; and a valve body 20 that moves relative to the valve port 13 when the rotor 41 rotates. A computer of the electric valve control device 70 detects a load on the rotor 41, using a change time that is required for the drive current flowing through the coil to change from a first current value to a second current value.

Description

Motor-operated valve control device, motor-operated valve device, and motor-operated valve load detection method

[0001] The present invention relates to an electric valve control device, an electric valve device having the electric valve control device, and a method for detecting a load on an electric valve.

[0002] Patent Documents 1 and 2 disclose examples of conventional motor-operated valves.

[0003] The motor-operated valve of Patent Document 1 has a valve body, a valve element, a drive shaft, a guide member, a gear mechanism, and a stepping motor. The valve body has a valve port. The valve element faces the valve port and is pushed away from the valve port by a valve-opening spring. The guide member has a female thread and is attached to the valve body. The drive shaft has a male thread that is threaded into the female thread of the guide member. The drive shaft is connected to the output shaft of the gear mechanism. The stepping motor has a rotor and a stator.

[0004] When a pulse is input to the stepping motor, the rotor rotates. Specifically, the rotor rotates when a drive current corresponding to the pulse is supplied to the stator coil. The rotation of the rotor is slowed down by a gear mechanism and transmitted to the drive shaft. When the drive shaft rotates, it moves due to the feed screw action. When the rotor rotates in the closing direction, the drive shaft pushes the valve disc, bringing the valve disc closer to the valve orifice. When the rotor rotates in the opening direction, the drive shaft moves away from the valve orifice, and the valve-opening spring pushes the valve disc, causing the valve disc to move away from the valve orifice.

[0005] The motor-operated valve of Patent Document 2 has a valve body, a valve element, a holder, a guide member, a stepping motor, and a stopper mechanism. The valve body has a valve port and a valve seat. The valve element faces the valve port. The holder has a female thread. The guide member has a male thread that screws into the female thread of the holder and is attached to the valve body. The stepping motor has a rotor and a stator. The holder is attached to the rotor and rotates together with the rotor.

[0006] When a pulse is input to the stepping motor, the rotor rotates. As the rotor rotates, the rotor and holder move due to the feed screw action. When the rotor rotates in the closing direction, the holder pushes the valve disc via the valve closing spring, causing the valve disc to approach the valve orifice. When the valve disc contacts the valve seat, the valve orifice closes. At this time, the rotor is in the closed position. As the rotor rotates further in the closing direction, the valve disc does not move and the valve closing spring is compressed. Then, when the rotor reaches the reference position, the stopper mechanism restricts the rotor's rotation in the closing direction. When the rotor rotates in the opening direction from the reference position, the rotor and holder move away from the valve orifice. When the rotor rotates in the opening direction and passes the closed position, the holder moves the valve disc away from the valve seat, opening the valve orifice. In other words, when the rotor is in the closed position, inputting K pulses (e.g., 1 to 10) to the stepping motor to rotate the rotor in the opening direction opens the valve orifice, and the rotor is in the open position.

[0007] JP 2018-135908 A Patent No. 7254400

[0008] In the motor-operated valve of Patent Document 1, play is provided between the gears of the gear mechanism. Play is also provided between the output shaft and the drive shaft. The play allows the gears and drive shaft to rotate and move smoothly. This motor-operated valve has a transmission state in which the rotation of the rotor is transmitted to the drive shaft, and a play state in which the rotation of the rotor is not transmitted to the drive shaft. In the play state, even if pulses are input to the stepping motor to rotate the rotor, the drive shaft does not rotate and the valve element does not move. When J pulses (e.g., 100) are input to the stepping motor to rotate the rotor in one direction, and then J pulses are input to the stepping motor to rotate it in the other direction, the motor-operated valve transitions from the transmission state to the play state and then to the transmission state, so the valve element does not return to the position it was in before the rotor was rotated in one direction.

[0009] In the motor-operated valve of Patent Document 2, the rotor position is controlled based on the number of pulses input to the stepping motor, and it is necessary to accurately obtain the pulse corresponding to the valve closed position.

[0010] In the motor-operated valve of Patent Document 1, the rotor load increases when the valve transitions from the idle state to the engaged state. In the motor-operated valve of Patent Document 2, the rotor load increases when the rotor rotates in the closing direction and reaches the closed valve position. Therefore, it is possible to determine whether the motor-operated valve has transitioned from the idle state to the engaged state or whether the rotor has reached the closed valve position based on the rotor load.

[0011] For example, a sensor (a rotation angle sensor or a Hall sensor) that outputs a signal corresponding to the rotor position can be incorporated into the motor-operated valve, and the rotor load can be detected using the signal. However, incorporating a sensor into the motor-operated valve complicates the structure of the motor-operated valve and increases manufacturing costs.

[0012] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric valve control device, an electric valve device, and a method for detecting a load on an electric valve that can detect the load on a rotor of a stepping motor with a relatively simple configuration.

[0013] The inventors conducted extensive research using multiple motor-operated valves to supply drive current to the stator coils and measure the drive current flowing through the coils, and discovered that there is a difference between the time it takes for the drive current to change from a first current value to a second current value when the rotor load is relatively light and the time it takes for the drive current to change from the first current value to the second current value when the rotor load is relatively heavy, leading to the present invention.

[0014] In order to achieve the above object, one aspect of the present invention provides an electric valve control device that controls an electric valve having a valve body with a valve port, a rotor and a stepping motor having a coil to which a drive current for rotating the rotor is supplied, and a valve body that moves relative to the valve port when the rotor rotates, and is characterized by having a processing device that detects the load on the rotor using the change time it takes for the drive current flowing through the coil to change from a first current value to a second current value.

[0015] In the present invention, the motor-operated valve has a drive shaft, a gear mechanism that transmits the rotation of the rotor to the drive shaft, and a guide member fixed to the valve body, the guide member having a female thread and the drive shaft having a male thread that is screwed into the female thread, or the drive shaft having a female thread and the guide member having a male thread that is screwed into the female thread, the motor-operated valve has a transmission state in which the rotation of the rotor is transmitted to the drive shaft and an idle state in which the rotation of the rotor is not transmitted to the drive shaft, when the drive shaft rotates, the valve body moves relative to the valve port, a motor driver is connected to the coil, and when pulses are input in a first sequence, the motor driver It is preferable that the driving current for rotating the rotor in a first direction is supplied to the coil, and when pulses are input in a second sequence, the driving current for rotating the rotor in a second direction is supplied to the coil, the processing device inputs pulses to the motor driver in the first sequence, subsequently inputs pulses to the motor driver in the second sequence, determines whether the motor-operated valve has transitioned from the idle state to the transmitted state based on the load on the rotor while inputting pulses in the second sequence, and when it is determined that the motor-operated valve has transitioned from the idle state to the transmitted state, obtains a correction number based on the number of pulses input in the second sequence.

[0016] In the present invention, when the number of pulses input to the motor driver to rotate the rotor from the current position to the target position is M and the correction number is C, it is preferable that the processing device (i) inputs M pulses to the motor driver when rotating the rotor from the current position to the target position in the same direction as the previous rotation direction, and (ii) inputs (C+M) pulses to the motor driver when rotating the rotor from the current position to the target position in the opposite direction to the previous rotation direction.

[0017] In the present invention, the motor-operated valve has a holder fixed to the rotor and a guide member fixed to the valve body, the holder has a female thread and the guide member has a male thread that is screwed into the female thread, or the guide member has a female thread and the holder has a male thread that is screwed into the female thread, when the rotor rotates in the closing direction, the rotor and the holder move in a direction approaching the valve orifice, the holder presses the valve body via a valve-closing spring, when the rotor rotates in the opening direction, the rotor and the holder move in a direction away from the valve orifice, the motor-operated valve has an open state in which the valve orifice is open and a closed state in which the valve orifice is closed, and a motor is connected to the coil. It is preferable that a driver is connected, the motor driver supplies the drive current to the coil for rotating the rotor in the closing direction when pulses are input in a first sequence, and supplies the drive current to the coil for rotating the rotor in the opening direction when pulses are input in a second sequence, the processing device inputs pulses to the motor driver in the first sequence, determines whether the motor-operated valve has transitioned from the open state to the closed state based on the load on the rotor while pulses are being input in the first sequence, and obtains the closed valve position in which the valve body contacts a valve seat surrounding the valve orifice based on the position of the rotor when it is determined that the motor-operated valve has transitioned from the open state to the closed state.

[0018] In the present invention, it is preferable that, after the processing device determines that the motor-operated valve has transitioned from the open valve state to the closed valve state, it determines whether the motor-operated valve has transitioned from the closed valve state to a rotation restriction state in which rotation of the rotor in the closing direction is restricted based on the amount of variation in the change time, and obtains a reference position at which rotation of the rotor in the closing direction is restricted based on the position of the rotor when it is determined that the motor-operated valve has transitioned from the closed valve state to the rotation restriction state.

[0019] In the present invention, it is preferable that a motor driver is connected to the coil, the motor driver supplies the drive current to the coil when a pulse is input, and the processing device increases the drive current when it determines that the load on the rotor is large, and decreases the drive current when it determines that the load on the rotor is small.

[0020] In order to achieve the above object, a motor-operated valve device according to another aspect of the present invention includes the motor-operated valve and the motor-operated valve control device.

[0021] In order to achieve the above object, another aspect of the present invention provides a load detection method for an electric valve having a valve body with a valve port, a stepping motor having a rotor and a coil to which a drive current for rotating the rotor is supplied, and a valve body that moves relative to the valve port when the rotor rotates, characterized in that the load on the rotor is detected using the change time required for the drive current flowing through the coil to change from a first current value to a second current value.

[0022] According to the present invention, the rotor load is detected using the time it takes for the drive current flowing through the stator coil to change from a first current value to a second current value. This allows the rotor load to be detected with a relatively simple configuration. Based on the rotor load, the number of pulses input to the stepping motor when the motor-operated valve is in an idle state can be obtained, and the rotor position (valve opening) can be corrected using this number of pulses. Furthermore, the closed valve position can be detected relatively accurately based on the rotor load.

[0023] 13 is a block diagram of an air conditioner having a motor-operated valve device according to a first embodiment of the present invention. It is a cross-sectional view of the motor-operated valve device of FIG. 1. It is a diagram schematically showing the rotor and stator of a stepping motor included in the motor-operated valve device of FIG. 1. It is a diagram schematically showing the stepping motor, computer, and motor driver included in the motor-operated valve device of FIG. 1. It is a diagram showing an example of the relationship between pulses and step signals and direction signals input to the motor driver. It is a diagram showing an example of the correspondence relationship between pulses and A-phase current target values ​​and B-phase current target values. It is a diagram schematically showing an example of the waveform of an A-phase current and a B-phase current. It is a diagram showing an example of the waveform of a drive current flowing through a stator coil (when the rotor load is low). It is a diagram showing an example of the waveform of a drive current flowing through a stator coil (when the rotor load is high). It is a diagram showing an example of the change time of the drive current in the motor-operated valve of the motor-operated valve device of FIG. 1. It is a flowchart showing an example of a correction number acquisition operation. It is a flowchart showing an example of a valve opening degree changing operation. It is a cross-sectional view of the motor-operated valve device according to a second embodiment of the present invention. It is a diagram schematically showing the stepping motor, computer, and motor driver included in the motor-operated valve device of FIG. Fig. 14 is a diagram showing an example of a change time of a drive current in the motor-operated valve of the motor-operated valve device of Fig. 13. Fig. 15 is a flowchart showing an example 1 of an initialization operation. Fig. 16 is a flowchart showing an example 2 of the initialization operation.

[0024] First Embodiment A motor-operated valve device according to a first embodiment of the present invention will now be described with reference to FIGS.

[0025] The motor-operated valve device 1 according to this embodiment is incorporated into, for example, the refrigeration cycle system of an air conditioner 500 and used as a flow control valve for controlling the flow rate of a refrigerant. The motor-operated valve device 1 has a motor-operated valve 5 and a motor-operated valve control device 70. Fig. 1 shows a block diagram of the air conditioner 500 having the motor-operated valve device 1. Fig. 2 shows a cross-sectional view of the motor-operated valve device 1.

[0026] The air conditioner 500 has a compressor 501, a condenser 502, an electric valve device 1 (electric valve 5), and an evaporator 503, which are connected in this order via piping 505. The electric valve device 1 is an expansion valve. The air conditioner 500 has an air conditioner control device 510. The air conditioner control device 510 is connected to the electric valve device 1 (electric valve control device 70) so that it can communicate with them. The air conditioner control device 510 uses the electric valve device 1 to control the flow rate of refrigerant flowing through the piping 505.

[0027] The motor-operated valve 5 includes a valve body 10 , a valve element 20 , a drive mechanism 30 , and a stator 60 .

[0028] The valve body 10 includes a housing 11 , a sleeve 14 , a connecting plate 15 , and a can 18 .

[0029] The housing 11 has a cylindrical shape with a bottom. The housing 11 has a valve chamber 12 and a valve port 13 connected to the valve chamber 12. A first conduit 16 is joined to the peripheral wall portion 11a of the housing 11. The first conduit 16 is connected to the valve chamber 12. A second conduit 17 is joined to the bottom wall portion 11b of the housing 11. The second conduit 17 is connected to the valve port 13 provided in the bottom wall portion 11b. An upward-facing annular flat surface 11c is provided on the inner peripheral surface of the peripheral wall portion 11a.

[0030] The sleeve 14 has a cylindrical shape. The sleeve 14 integrally includes a cylindrical portion 14a and a flange portion 14b. The inner diameter of the upper portion of the cylindrical portion 14a is larger than the inner diameter of the lower portion of the cylindrical portion 14a. The flange portion 14b has an annular shape. The inner peripheral edge of the flange portion 14b is connected to the upper end of the cylindrical portion 14a. The flange portion 14b is in contact with an annular flat surface 11c of the housing 11. An upward-facing annular flat surface 14c is provided on the inner peripheral surface of the cylindrical portion 14a.

[0031] The connecting plate 15 has a circular ring shape. A peripheral wall portion 11a is disposed inside the connecting plate 15. The inner peripheral edge of the connecting plate 15 is joined to the peripheral wall portion 11a.

[0032] The can 18 has a cylindrical shape. The can 18 has an open lower end and a closed upper end. The lower end of the can 18 is joined to the outer periphery of the connecting plate 15.

[0033] The valve element 20 has a body portion 21, a valve portion 22, a spring receiving portion 23, and a ball receiving portion 24. The body portion 21 has a cylindrical shape. The valve portion 22 has a conical shape with its tip facing downward. The valve portion 22 is coaxially connected to the lower end of the body portion 21. The valve portion 22 faces the valve port 13 in the vertical direction (direction of the axis L). The spring receiving portion 23 has an annular shape. The outer diameter of the spring receiving portion 23 is larger than the outer diameter of the body portion 21. The inner peripheral edge of the spring receiving portion 23 is connected to the upper end of the body portion 21. The body portion 21, the valve portion 22, and the spring receiving portion 23 are integrally formed. The ball receiving portion 24 is attached to the upper end surface of the body portion 21.

[0034] The body 21 is disposed inside the cylindrical portion 14a of the sleeve 14 and is supported by the lower portion of the cylindrical portion 14a so as to be movable up and down. A valve-opening spring 25 is disposed between the spring bearing portion 23 and the annular flat surface 14c of the sleeve 14. The valve-opening spring 25 is a compression coil spring and presses the valve element 20 upward.

[0035] The drive mechanism 30 moves the valve element 20 in the up and down direction. The drive mechanism 30 is disposed inside the can 18. The drive mechanism 30 has a drive shaft 31, a guide member 35, a rotor 41, a connecting member 42, a rotor shaft 43, a support member 44, and a planetary gear mechanism 50.

[0036] The drive shaft 31 has a cylindrical portion 32, a flat portion 33, and a ball 34. The cylindrical portion 32 has a male thread 32t. The male thread 32t is disposed on the outer peripheral surface of the cylindrical portion 32. The flat portion 33 extends upward from the upper end surface of the cylindrical portion 32. The cylindrical portion 32 and the flat portion 33 are integrally formed. The ball 34 is joined to the lower end surface of the cylindrical portion 32. The drive shaft 31 is connected to the valve body 20. Specifically, the ball 34 of the drive shaft 31 is in slidable contact with the ball receiving portion 24 of the valve body 20.

[0037] The guide member 35 has a cylindrical shape. The guide member 35 is disposed inside the upper portion of the peripheral wall portion 11a of the housing 11. The guide member 35 is fixed to the peripheral wall portion 11a. The flange portion 14b of the sleeve 14 is held between the lower end surface of the guide member 35 and the annular flat surface 11c of the peripheral wall portion 11a. The guide member 35 has a female thread 35t. The female thread 35t is disposed on the lower portion of the inner peripheral surface of the guide member 35. The male thread 32t of the drive shaft 31 is threadedly engaged with the female thread 35t. The drive shaft 31 may have a female thread, and the guide member 35 may have a male thread.

[0038] The rotor 41 has a cylindrical shape. The rotor 41 is rotatable relative to the valve body 10. The rotor 41 has multiple magnetic poles (multiple north poles and multiple south poles). The multiple north poles and multiple south poles are arranged on the outer circumferential surface of the rotor 41. 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. The rotor 41 has, for example, 12 north poles and 12 south poles. The position (angle) of the rotor 41 is related to the opening degree of the valve port 13 (valve opening degree). Figure 3 schematically shows the rotor 41 and the stator 60. In Figure 3, the radially outer side of the diagram shown as the stator 60 corresponds to the upper side of the stator 60, and the radially inner side corresponds to the lower side.

[0039] The connecting member 42 has a disk shape. The connecting member 42 connects the upper end of the rotor 41 and the rotor shaft 43. The connecting member 42 rotates together with the rotor 41. The support member 44 is disposed above the rotor 41. The support member 44 rotatably supports the upper end of the rotor shaft 43.

[0040] The planetary gear mechanism 50 decelerates the rotation of the rotor 41. The planetary gear mechanism 50 connects the rotor 41 and the drive shaft 31 and transmits the rotation of the rotor 41 to the drive shaft 31. The planetary gear mechanism 50 is disposed inside the rotor 41. The planetary gear mechanism 50 has a gear case 51, a fixed ring gear 52, a sun gear 53, a plurality of planet gears 54, a carrier 55, an output gear 56, and an output shaft 57.

[0041] The gear case 51 has a cylindrical shape. The gear case 51 is fixed to the upper part of the peripheral wall portion 11a of the housing 11. The fixed ring gear 52 is an internal gear. The fixed ring gear 52 is fixed to the upper part of the gear case 51. The sun gear 53 is connected to the lower surface of the connecting member 42. The sun gear 53 and the connecting member 42 are integrally formed. The rotor shaft 43 is inserted inside the sun gear 53. The multiple planetary gears 54 surround the sun gear 53. The multiple planetary gears 54 mesh with the fixed ring gear 52 and the sun gear 53. The carrier 55 has a plate shape. The carrier 55 has a support shaft that rotatably supports the multiple planetary gears 54. The output gear 56 is an internal gear having a cylindrical shape with a bottom. The output gear 56 meshes with the multiple planetary gears 54.

[0042] The output shaft 57 has a cylindrical shape. A lower portion of the output shaft 57 is disposed inside the guide member 35. The output shaft 57 is rotatably supported by the guide member 35. An upper portion of the output shaft 57 is fixed to the bottom portion of the output gear 56. The output shaft 57 rotates together with the output gear 56. The output shaft 57 has a bearing hole in which the lower end of the rotor shaft 43 is disposed. The output shaft 57 rotatably supports the lower end of the rotor shaft 43.

[0043] The output shaft 57 has a slit 57a extending in the vertical direction. The slit 57a is located at the bottom of the output shaft 57. The width of the slit 57a is the same as the thickness of the flat plate portion 33 of the drive shaft 31. The output shaft 57 is connected to the drive shaft 31. Specifically, the flat plate portion 33 is located in the slit 57a so as to be movable in the vertical direction. When the output shaft 57 rotates, the flat plate portion 33 (drive shaft 31) rotates, and the flat plate portion 33 moves in the vertical direction within the slit 57a.

[0044] The stator 60 has a cylindrical shape and includes an A-phase stack 61 and a B-phase stack 62 .

[0045] The A-phase stack 61 has a plurality of claw-pole-type pole teeth 61a, 61b. The tip of the pole tooth 61a faces downward, and the tip of the pole tooth 61b faces upward. The pole teeth 61a and the pole teeth 61b are alternately arranged at equal angular intervals in the circumferential direction. The A-phase stack 61 has, for example, 12 pole teeth 61a and 12 pole teeth 61b. The A-phase stack 61 has an A-phase coil 61c. When the A-phase coil 61c is energized, the pole teeth 61a and the pole teeth 61b become magnetic poles of mutually opposite polarities.

[0046] The B-phase stack 62 has a plurality of claw-pole-shaped pole teeth 62a, 62b. The tips of the pole teeth 62a face downward, and the tips of the pole teeth 62b face upward. The pole teeth 62a and the pole teeth 62b are alternately arranged at equal angular intervals in the circumferential direction. The B-phase stack 62 has, for example, 12 pole teeth 62a and 12 pole teeth 62b. The B-phase stack 62 has a B-phase coil 62c. When the B-phase coil 62c is energized, the pole teeth 62a and the pole teeth 62b become magnetic poles of mutually opposite polarities. The B-phase stack 62 has the same configuration as the A-phase stack 61.

[0047] The A-phase stack 61 is disposed on top of the B-phase stack 62. The B-phase stack 62 is located at a position rotated by an angle α about the axis L relative to the A-phase stack 61 from a position where the pole teeth 61 a and 62 a are aligned in the direction of the axis L. The angle α is half the angle between the pole teeth 61 a and 61 b. The pole teeth 61 a, 61 b ​​of the A-phase stack 61 and the pole teeth 62 a, 62 b of the B-phase stack 62 form the inner circumferential surface of the stator 60.

[0048] The can 18 is disposed inside the stator 60. The rotor 41 is disposed inside the can 18. The magnetic poles of the rotor 41 and the pole teeth 61a, 61b, 62a, and 62b of the stator 60 face each other in the radial direction, with the can 18 sandwiched between them. The stator 60 and the rotor 41 form a stepping motor 66. The stepping motor 66 is controlled by an electric valve control device 70. Note that the configuration of the stepping motor 66 described above (e.g., the number of magnetic poles of the rotor 41 and the number of pole teeth of the stator 60) is an example and can be changed depending on the application of the electric valve device 1, etc.

[0049] In this embodiment, the stepping motor 66 is controlled using a two-phase excitation method. Pulses P (P[1] to P[4]) are input to the stepping motor 66, causing the rotor 41 to rotate. Specifically, a motor driver 77 of the motor-operated valve control device 70 is connected to the stator 60 of the stepping motor 66. When pulses P are input to the motor driver 77, a drive current corresponding to the pulses P is supplied to the stator 60, causing the rotor 41 to rotate. In this specification, "inputting pulses P to the stepping motor 66" is synonymous with "inputting pulses P to the motor driver 77, causing the drive current corresponding to the pulses P to be supplied to the stator 60." The stepping motor 66 may be controlled using a one-phase excitation method, a one-two-phase excitation method, a W1-2-phase excitation method, a two-phase excitation method, or a four-phase excitation method.

[0050] When pulses P are cyclically input to the stepping motor 66 in ascending order (the order of pulses P[1] to P[4]), the rotor 41 rotates in the closing direction (clockwise in FIG. 3 ). The rotation of the rotor 41 is transmitted to the drive shaft 31 by the planetary gear mechanism 50. As the drive shaft 31 rotates, the drive shaft 31 moves downward due to the feed screw action. The drive shaft 31 pushes the valve element 20 downward. As the valve element 20 moves downward, the valve portion 22 approaches the valve orifice 13, reducing the opening of the valve orifice 13. When the valve portion 22 contacts the periphery (valve seat) of the valve orifice 13, the opening of the valve orifice 13 is minimized (zero). At this time, the rotor 41 is in the closed valve position Rc. When the opening of the valve orifice 13 is minimized, a gap may be formed between the valve portion 22 and the valve seat.

[0051] When pulses P are cyclically input to the stepping motor 66 in descending order (in the order of pulses P[4] to P[1]), the rotor 41 rotates in the opening direction (counterclockwise in FIG. 3). The rotation of the rotor 41 is transmitted to the drive shaft 31 by the planetary gear mechanism 50. When the drive shaft 31 rotates, the drive shaft 31 moves upward due to the feed screw action. The valve element 20, pressed by the valve-opening spring 25, moves upward, and the valve portion 22 moves away from the valve orifice 13, increasing the opening degree of the valve orifice 13. When the valve portion 22 is furthest from the valve orifice 13, the opening degree of the valve orifice 13 is at its maximum. At this time, the rotor 41 is at the fully open position Rz. The number of pulses P required to rotate the rotor 41 from the closed valve position Rc to the fully open position Rz is, for example, 1,500.

[0052] There is play between the gears of the planetary gear mechanism 50. There is also play between the output shaft 57 and the drive shaft 31. The play allows the gears and the drive shaft 31 to rotate and move smoothly. The motor-operated valve 5 has a transmission state ST in which the rotation of the rotor 41 is transmitted to the drive shaft 31, and a play state SP in which the rotation of the rotor 41 is not transmitted to the drive shaft 31. In the transmission state ST, when a pulse P is input to the stepping motor 66 to rotate the rotor 41, the drive shaft 31 rotates and the valve disc 20 moves. In the play state SP, even when a pulse P is input to the stepping motor 66 to rotate the rotor 41, the drive shaft 31 does not rotate and the valve disc 20 does not move.

[0053] The housing 11, valve port 13, sleeve 14, can 18, valve body 20, drive shaft 31, guide member 35, rotor 41, connecting member 42, rotor shaft 43, fixed ring gear 52, sun gear 53, output gear 56, output shaft 57, and stator 60 (A-phase stack 61, B-phase stack 62) each have a central axis that coincides with the axis L.

[0054] The motor-operated valve control device 70 has a substrate 71 on which a plurality of electronic components (not shown) are mounted. The motor-operated valve control device 70 also has a non-volatile memory 75, a communication device 76, a motor driver 77, and a computer 80. The motor-operated valve control device 70 controls the motor-operated valve 5 based on commands received from the air conditioner control device 510.

[0055] The nonvolatile memory 75 stores data that needs to be retained even when the power is cut off. For example, the nonvolatile memory 75 stores the position (current position Rp) of the rotor 41 immediately before the power to the motor-operated valve control device 70 is cut off. The nonvolatile memory 75 is, for example, an EEPROM or a flash memory.

[0056] The communication device 76 is communicably connected to the air conditioner control device 510 via a wired communication bus 520. The air conditioner 500 employs a communication method such as Local Interconnect Network (LIN) or Controller Area Network (CAN). The communication device 76 may also be connected to the air conditioner control device 510 wirelessly.

[0057] The motor driver 77 is controlled by the computer 80. The motor driver 77 supplies a drive current to the stator 60 to rotate the rotor 41. As shown in FIG. 4 , the motor driver 77 is connected to terminals A1 and A2 of the A-phase coil 61c and terminals B1 and B2 of the B-phase coil 62c. The motor driver 77 supplies an A-phase current Ia to the A-phase coil 61c and a B-phase current Ib to the B-phase coil 62c. The motor driver 77 may be provided in the motor-operated valve 5.

[0058] The motor driver 77 receives a step signal (STEP) and a direction signal (DIR) from the computer 80. The step signal is a pulse signal. When a direction signal corresponding to the closing direction (e.g., an H-level signal) is input to the motor driver 77, the step signal is input, which corresponds to pulses P being input to the stepping motor 66 (motor driver 77) in ascending order. When a direction signal corresponding to the opening direction (e.g., an L-level signal) is input to the motor driver 77, the step signal is input, which corresponds to pulses P being input to the stepping motor 66 (motor driver 77) in descending order. FIG. 5 schematically shows an example of the relationship between the pulses P and the step signal and direction signal input to the motor driver 77.

[0059] In addition, a current control signal (CTRL) is input to the motor driver 77 from the computer 80. The current control signal is a signal for setting target values ​​of the A-phase current Ia and the B-phase current Ib (A-phase current target value and B-phase current target value) in the motor driver 77.

[0060] FIG. 6 shows an example of the correspondence between pulse P and the A-phase current target value and B-phase current target value. For pulse P[1], "+It" is set as the A-phase current target value, and "-It" is set as the B-phase current target value. For pulse P[2], "+It" is set as the A-phase current target value, and "+It" is set as the B-phase current target value. For pulse P[3], "-It" is set as the A-phase current target value, and "+It" is set as the B-phase current target value. For pulse P[4], "-It" is set as the A-phase current target value, and "-It" is set as the B-phase current target value. "+It" and "-It" have the same current magnitude but different current directions. The magnitude of the target value (|It|) is, for example, 200 to 600 mA.

[0061] FIG. 7 shows a schematic example of the waveform of the A-phase current Ia and the waveform of the B-phase current Ib when pulses P are input to the stepping motor 66 in ascending order.

[0062] 6 and 7, the signs (+ / -) indicate the direction of current flow. "+" indicates the direction from terminal A1 to terminal A2, or from terminal B1 to terminal B2. "-" indicates the direction from terminal A2 to terminal A1, or from terminal B2 to terminal B1.

[0063] The pulses P are input to the stepping motor 66 at a predetermined input speed. In this embodiment, the input speed of the pulses P is 100 to 500 pps (pulses per second). The stepping motor 66 is controlled in a full-step manner. The stepping motor 66 may also be controlled in a half-step manner or a micro-step manner. The step angle of the stepping motor 66 is, for example, 7.5 degrees.

[0064] The computer 80 is a microcomputer for an embedded device in which a CPU, ROM, RAM, an input / output interface (I / O), an analog-to-digital converter (ADC), etc. are integrated into one package. The computer 80 may include a non-volatile memory 75, a communication device 76, and a motor driver 77. The computer 80 is a processing device.

[0065] The computer 80 has two output ports. The two output ports are connected to the motor driver 77. The computer 80 outputs a step signal (STEP) from one output port and a direction signal (DIR) from the other output port. The computer 80 has a communication port, which is connected to the motor driver 77. The computer 80 outputs a current control signal (CTRL) from the communication port. Information provided by the motor driver 77 is input to the computer 80 from the communication port.

[0066] The computer 80 has an input port. The input port is connected to the motor driver 77. A voltage Via corresponding to the A-phase current Ia is input to the input port, and the voltage Via is converted by an ADC into information indicating the A-phase current Ia flowing through the A-phase coil 61c. A voltage Vib corresponding to the B-phase current Ib is input to the input port, and the voltage Vib is converted by the ADC into information indicating the B-phase current Ib flowing through the B-phase coil 62c. The computer 80 (CPU) obtains the information converted by the ADC as the A-phase current Ia and the B-phase current Ib.

[0067] The computer 80 functions as a rotation control unit 81, an acquisition unit 82, and a detection unit 83 by the CPU executing a program stored in the ROM.

[0068] The rotation control unit 81 inputs pulses P to the stepping motor 66 to rotate the rotor 41 in the closing or opening direction. Specifically, the rotation control unit 81 inputs a step signal, a direction signal, and a current control signal to the motor driver 77. The rotation control unit 81 controls the motor driver 77 based on a command from the air conditioner control device 510 to supply an A-phase current Ia to the A-phase coil 61c and a B-phase current Ib to the B-phase coil 62c.

[0069] The A-phase current Ia alternates between a first current value and a second current value. The acquisition unit 82 acquires the time it takes for the A-phase current Ia flowing through the A-phase coil 61c to change from the first current value to the second current value.

[0070] The B-phase current Ib alternates between a first current value and a second current value. The acquisition unit 82 acquires the time it takes for the B-phase current Ib flowing through the B-phase coil 62c to change from the first current value to the second current value.

[0071] The change time when the first current value is "-It" and the second current value is "+It" is called the "rise time." The change time when the first current value is "+It" and the second current value is "-It" is called the "fall time."

[0072] The acquisition unit 82 acquires the change time based on, for example, the A-phase current Ia and the B-phase current Ib acquired via an ADC. If the motor driver 77 has a function for providing the change time, the acquisition unit 82 may acquire the change time from the motor driver 77 via a communication port.

[0073] The detection unit 83 detects the load on the rotor 41 using the change time acquired by the acquisition unit 82 .

[0074] The inventors supplied drive currents (A-phase current Ia and B-phase current Ib) to the coils (A-phase coil 61c and B-phase coil 62c) of the stator 60 of the motor-operated valve 5, and observed the waveforms of the drive currents flowing through the coils. Fig. 8 shows an example of the waveform of the drive current when the load on the rotor 41 is relatively small. Fig. 9 shows an example of the waveform of the drive current when the load on the rotor 41 is relatively large. In Figs. 8 and 9, the change time rt is the rise time, and the change time ft is the fall time.

[0075] 8 and 9, the waveform of the drive current when the load on the rotor 41 is large reaches the target value (+It, -It) in a shorter time than the waveform of the drive current when the load on the rotor 41 is small. This is thought to be because when the load on the rotor 41 is large, the angular velocity of the rotor 41 decreases, reducing the electromotive force generated in the coil by the rotation of the rotor 41 and preventing the electromotive force from interfering with changes in the drive current. Therefore, the load on the rotor 41 can be detected based on the change time.

[0076] Next, the inventors measured the change in the drive current flowing through the coil when pulses P were input to the stepping motor 66 in ascending order to rotate the rotor 41 in the closing direction (first direction), and then pulses P were input to the stepping motor 66 in descending order to rotate the rotor 41 in the opening direction (second direction). Figure 10 shows an example of the change in time measured over time. Each black dot corresponds to a change time. In Figure 10, before time t1, the motor-operated valve 5 is in the transmission state ST, and the rotation of the rotor 41 is transmitted to the drive shaft 31. At time t1, the rotation direction D of the rotor 41 switches from the closing direction to the opening direction, and the motor-operated valve 5 transitions from the transmission state ST to the play state SP, and the rotation of the rotor 41 is not transmitted to the drive shaft 31. Then, at time t2, the motor-operated valve 5 transitions from the play state SP to the transmission state ST, and the rotation of the rotor 41 is transmitted to the drive shaft 31.

[0077] As shown in Figure 10, the change time is short when the motor-operated valve 5 is in the transmission state ST, and long when the motor-operated valve 5 is in the play state SP. This is thought to be because when the motor-operated valve 5 is in the transmission state ST, a force is required to rotate the drive shaft 31, so the load on the rotor 41 is large, and when the motor-operated valve 5 is in the play state SP, the gear rotates within the range of play, so the load on the rotor 41 is small. Furthermore, the difference (variation) between the maximum and minimum values ​​of the change time when the motor-operated valve 5 is in the transmission state ST is small, and the difference between the maximum and minimum values ​​of the change time when the motor-operated valve 5 is in the play state SP is large. Therefore, the state of the motor-operated valve 5 can be determined based on the change time, which is related to the load on the rotor 41.

[0078] When power is turned on, the motor-operated valve control device 70 reads the position of the rotor 41 from the nonvolatile memory 75 and sets it as the current position Rp. The motor-operated valve control device 70 stores in the nonvolatile memory 75 the position of the rotor 41 immediately before power is cut off.

[0079] Next, an example of the operation of the motor-operated valve control device 70 to obtain a correction number will be described with reference to Fig. 11. Fig. 11 shows a flowchart of the example of the operation of obtaining a correction number. The computer 80 of the motor-operated valve control device 70 reads the current position Rp of the rotor 41 from the non-volatile memory 75, and then executes the operation of obtaining a correction number.

[0080] In the correction number acquisition operation, the angle from the current position Rp to the closed valve position Rc is defined as θc, and the angle corresponding to Na pulses P is defined as θa (θa = Na × step angle). Na is the number of pulses P sufficient for the motor-operated valve 5 to transition from the play state SP to the transmission state ST. Na is set appropriately depending on the configuration of the motor-operated valve device 1. For example, Na is 100. When θc > θa, the motor-operated valve control device 70 determines the ascending order as the first order, the descending order as the second order, the closing direction as the first direction, and the opening direction as the second direction. When θc ≦ θa, the motor-operated valve control device 70 determines the descending order as the first order, the ascending order as the second order, the opening direction as the first direction, and the closing direction as the second direction.

[0081] The motor-operated valve control device 70 inputs Na pulses P in a first sequence to the stepping motor 66 (motor driver 77) (S110), and supplies a drive current to the coil of the stator 60 to rotate the rotor 41 in the first direction. The rotor 41 rotates in the first direction.

[0082] The motor-operated valve control device 70 inputs pulses P to the stepping motor 66 in the second sequence (S120), supplying a drive current to the coil of the stator 60 to rotate the rotor 41 in the second direction. The rotation direction D of the rotor 41 switches from the first direction to the second direction, and the motor-operated valve 5 transitions from the transmission state ST to the idle state SP.

[0083] Next, the motor-operated valve control device 70 determines whether the motor-operated valve 5 has transitioned from the play state SP to the transmission state ST (S130). Specifically, the motor-operated valve control device 70 acquires a change time Ta of the drive current when pulses P are being input to the stepping motor 66 in the second sequence, and compares the change time Ta with a criterion value Th. The criterion value Th is set, for example, based on a plurality of change times Ta acquired when the motor-operated valve 5 is in the transmission state ST and a plurality of change times Ta acquired when the motor-operated valve 5 is in the play state SP. A single criterion value Th may be used for the rise time and fall time of the A-phase current Ia and the rise time and fall time of the B-phase current Ib, or individual criterion values ​​Th may be used.

[0084] When the change time Ta is greater than the determination value Th, the motor-operated valve control device 70 determines that the motor-operated valve 5 is in the play state SP (N in S130), and returns to step S120.

[0085] When the change time Ta is equal to or less than the determination value Th, the motor-operated valve control device 70 determines that the motor-operated valve 5 has transitioned to the transmission state ST (Y in S130) and acquires a correction number C (S140). The correction number C is used to correct the position of the rotor 41 (valve opening). Specifically, the motor-operated valve control device 70 counts the number Nt of pulses P input in the second sequence until it determines that the motor-operated valve 5 has transitioned to the transmission state ST. The motor-operated valve control device 70 determines the correction number C by subtracting the number Nb from the number Nt (C = Nt - Nb). Nb is set appropriately depending on the configuration of the motor-operated valve device 1. For example, Nb is 1. The motor-operated valve control device 70 then terminates the correction number acquisition operation.

[0086] The motor-operated valve control device 70 may use the amount of variation in the change time Ta to determine whether the motor-operated valve 5 has transitioned from the play state SP to the transmission state ST. The amount of variation is, for example, the standard deviation of multiple change times Ta. The amount of variation may also be the difference between the maximum and minimum values ​​of the multiple change times Ta. Specifically, the motor-operated valve control device 70 determines that the motor-operated valve 5 is in the play state SP when the amount of variation in multiple change times Ta is greater than a judgment value for the amount of variation, and determines that the motor-operated valve 5 is in the transmission state ST when the amount of variation is equal to or less than the judgment value.

[0087] The motor-operated valve control device 70 may also be configured to acquire the correction number C using only the change time of one of the A-phase current Ia and the B-phase current Ib. Alternatively, the motor-operated valve control device 70 may be configured to acquire the correction number C using only one of the rise time and fall time. In these configurations, the number Nb is set appropriately.

[0088] Next, an example of the valve opening change operation of the motor-operated valve control device 70 will be described with reference to Fig. 12. Fig. 12 shows a flowchart of an example of the valve opening change operation. When the computer 80 of the motor-operated valve control device 70 receives a valve opening change command from the air conditioner control device 510, it executes the valve opening change operation. The valve opening change command includes a target value for the valve opening.

[0089] The motor-operated valve control device 70 controls the position of the rotor 41 based on the number of pulses P input to the stepping motor 66. For example, the number of pulses P required to rotate the rotor 41 from the closed position Rc to the fully open position Rz is assumed to be 1500. The motor-operated valve control device 70 sets the positions of the rotor 41 from the closed position Rc to the fully open position Rz as positions [0] to

[1500] . The motor-operated valve control device 70 assigns a valve opening to each position, with position [0] representing a valve opening of 0% and position

[1500] representing a valve opening of 100%. The motor-operated valve control device 70 increases a number (index) indicating the position of the rotor 41 when pulses P are input to the stepping motor 66 in descending order, and decreases the number when pulses P are input to the stepping motor 66 in ascending order.

[0090] In the valve opening change operation, the electric valve control device 70 acquires a control number M, which is the number of pulses P required to rotate the rotor 41 from the current position Rp corresponding to the current value of the valve opening to the target position Rt corresponding to the target value of the valve opening (S210).

[0091] Specifically, assuming that the current position Rp is position [k] and the target position Rt is position [j], the electric valve control device 70 determines the difference between k and j (|k-j|) as the control number M. For example, when the current valve opening is 50% (current position Rp is position

[750] ) and the target valve opening is 40% (target position Rt is position

[600] ), the control number M is 150 (M = |750-600|). When the current valve opening is 40% (current position Rp is position

[600] ) and the target valve opening is 80% (target position Rt is position

[1200] ), the control number M is 600 (M = |600-1200|).

[0092] The motor-operated valve control device 70 acquires the rotation direction D of the rotor 41 (S220). Specifically, when the current position Rp is farther from the closed valve position Rc than the target position Rt, the motor-operated valve control device 70 determines the closing direction as the rotation direction D. When the current position Rp is closer to the closed valve position Rc than the target position Rt, the motor-operated valve control device 70 determines the opening direction as the rotation direction D.

[0093] The motor-operated valve control device 70 stores in RAM the previous rotation direction Dp of the rotor 41. The motor-operated valve control device 70 determines whether the rotation direction D is the same as the previous rotation direction Dp (S230).

[0094] When the rotation direction D is the same as the previous rotation direction Dp (Y in S230), the motor-operated valve control device 70 inputs M pulses P to the stepping motor 66 in the order corresponding to the rotation direction D (S240), and supplies a drive current to the coil of the stator 60. When the rotation direction D is the same as the previous rotation direction Dp, the motor-operated valve 5 is in the transmission state ST. Therefore, the rotor 41 rotates in the rotation direction D by an angle corresponding to the M pulses P, and is positioned at the target position Rt. The motor-operated valve control device 70 sets the target position Rt as a new current position Rp.

[0095] When the rotation direction D is opposite to the previous rotation direction Dp (N in S230), the motor-operated valve control device 70 inputs (C+M) pulses P to the stepping motor 66 in the order corresponding to the rotation direction D (S250) and supplies a driving current to the coil of the stator 60. When the rotation direction D is opposite to the previous rotation direction Dp, the motor-operated valve 5 transitions to the transmission state ST via the idle state SP. Therefore, the rotor 41 rotates in the rotation direction D by an angle corresponding to C pulses P to reach the position immediately before the motor-operated valve 5 transitioned to the transmission state ST. The rotor 41 then rotates in the rotation direction D by an angle corresponding to M pulses P to be positioned at the target position Rt. The motor-operated valve control device 70 sets the target position Rt as a new current position Rp. That is, the motor-operated valve control device 70 controls the position of the rotor 41 based on the number of pulses P input to the stepping motor 66, but does not include the correction number C in the number of pulses P input to the stepping motor 66.

[0096] The motor-operated valve control device 70 stores the rotation direction D in the RAM as the previous rotation direction Dp (S260), and then ends the valve opening degree changing operation.

[0097] As described above, the motor-operated valve device 1 includes the motor-operated valve 5 and the motor-operated valve control device 70. The motor-operated valve 5 includes the valve body 10 having the valve port 13, the stepping motor 66 having the rotor 41 and coils (A-phase coil 61c and B-phase coil 62c) to which a drive current for rotating the rotor 41 is supplied, and the valve element 20 that moves relative to the valve port 13 when the rotor 41 rotates. The motor-operated valve control device 70 includes a computer 80 that detects the load on the rotor 41 using the change time Ta, which is the time it takes for the drive current flowing through the coil to change from a first current value to a second current value. This allows the motor-operated valve control device 70 to detect the load on the rotor 41 with a relatively simple configuration. Furthermore, the motor-operated valve control device 70 can determine the state of the motor-operated valve 5 based on the load on the rotor 41 (change time Ta).

[0098] The motor-operated valve 5 also includes a drive shaft 31, a planetary gear mechanism 50 that transmits the rotation of the rotor 41 to the drive shaft 31, and a guide member 35 fixed to the valve body 10. The guide member 35 has a female thread 35t, and the drive shaft 31 has a male thread 32t that is threadedly engaged with the female thread 35t. The motor-operated valve 5 has a transmission state ST in which the rotation of the rotor 41 is transmitted to the drive shaft 31, and a play state SP in which the rotation of the rotor 41 is not transmitted to the drive shaft 31. When the drive shaft 31 rotates, the valve body 20 moves relative to the valve port 13. A motor driver 77 is connected to the coil. When pulses P are input from the motor driver 77 in a first sequence, the motor driver 77 supplies a drive current to the coil for rotating the rotor 41 in a first direction, and when pulses P are input in a second sequence, the motor driver 77 supplies a drive current to the coil for rotating the rotor 41 in a second direction. The computer 80 inputs pulses P to the motor driver 77 in a first sequence, and then inputs pulses P to the motor driver 77 in a second sequence. While the computer 80 is inputting pulses P in the second sequence, it determines whether the motor-operated valve 5 has transitioned from the play state SP to the transmission state ST based on the load on the rotor 41. When the computer 80 determines that the motor-operated valve 5 has transitioned from the play state SP to the transmission state ST, it acquires a correction number C based on the number of pulses P input in the second sequence. In this manner, the motor-operated valve control device 70 can acquire the correction number C, which is the number of pulses P for rotating the rotor 41 by an angle corresponding to the play of the drive shaft 31 and the planetary gear mechanism 50, and can correct the position of the rotor 41 (valve opening) using the correction number C.

[0099] Furthermore, the number of pulses P input to the motor driver 77 to rotate the rotor 41 from the current position Rp to the target position Rt is defined as M, and the correction number is defined as C. When the computer 80 (i) rotates the rotor 41 in the same direction as the previous rotation direction Dp to rotate it from the current position Rp to the target position Rt, it inputs M pulses P to the motor driver 77. When the computer 80 (ii) rotates the rotor 41 in the opposite direction to the previous rotation direction Dp to rotate it from the current position Rp to the target position Rt, it inputs (C+M) pulses P to the motor driver 77. In this way, the motor-operated valve control device 70 can correct the position of the rotor 41 using the correction number C, and can accurately control the valve opening of the motor-operated valve 5.

[0100] Second Embodiment A motor-operated valve device according to a second embodiment of the present invention will now be described with reference to FIGS.

[0101] The motor-operated valve device 101 according to this embodiment can be incorporated into the refrigeration cycle system of the air conditioner 500 shown in Fig. 1 in place of the motor-operated valve device 1 according to the first embodiment. The motor-operated valve device 101 has a motor-operated valve 105 and a motor-operated valve control device 170. Fig. 13 shows a cross-sectional view of the motor-operated valve device 101.

[0102] The motor-operated valve 105 includes a valve body 110 , a can 120 , a valve element 130 , a drive mechanism 140 , and a stator 160 .

[0103] The valve body 110 includes a main body member 111 and a connecting member 113. The main body member 111 has a cylindrical shape. The main body member 111 has a valve chamber 114 and a valve port 117 connected to the valve chamber 114. A first conduit 115 and a second conduit 116 are joined to the main body member 111. The first conduit 115 is connected to the valve chamber 114. The second conduit 116 is connected to the valve port 117. The main body member 111 has an annular valve seat 118 that surrounds the valve port 117 in the valve chamber 114. The main body member 111 has a circular fitting hole 111a. The fitting hole 111a is located on the upper end surface of the main body member 111. A through hole 111b that communicates with the valve chamber 114 is provided in the bottom surface of the fitting hole 111a. The connecting member 113 has an annular plate shape. The inner peripheral edge of the connecting member 113 is joined to the upper end of the main body member 111 .

[0104] The can 120 has a cylindrical shape. The can 120 has an open bottom end and a closed top end. The bottom end of the can 120 is joined to the outer periphery of the connecting member 113.

[0105] The valve body 130 has a shaft portion 131 and a valve portion 133. The shaft portion 131 has a cylindrical shape. The shaft portion 131 has a step portion 134, which is an annular flat surface facing upward. The valve portion 133 has a conical shape with its tip facing downward. The valve portion 133 is coaxially connected to the lower end of the shaft portion 131. The valve portion 133 is disposed in the valve port 117. The valve portion 133 faces the valve port 117 and the valve seat 118. When the valve portion 133 contacts the valve seat 118, the valve port 117 closes. When the valve portion 133 moves away from the valve seat 118, the valve port 117 opens.

[0106] The drive mechanism 140 moves the valve element 130 in the vertical direction (the direction of the axis L). The movement of the valve element 130 opens and closes the valve port 117. The drive mechanism 140 has a rotor 141, a valve stem holder 142, a movable stopper 142s, a guide bush 143, a stopper member 144, a fixed stopper 144s, a retaining member 145, and a valve-closing spring 147.

[0107] The rotor 141 has a cylindrical shape. The rotor 141 is disposed inside the can 120. The rotor 141 has substantially the same configuration as the rotor 41 of the first embodiment. The position (angle) of the rotor 141 is related to the opening degree of the valve port 117 (valve opening degree).

[0108] The valve stem holder 142 has a cylindrical shape. The lower end of the valve stem holder 142 is open. The valve stem holder 142 has an upper wall portion 142a with a shaft hole 142b formed therein. The valve stem holder 142 is fitted into a fitting hole 141a of the rotor 141 and rotates together with the rotor 141. The valve stem holder 142 is fixed to the rotor 141. A movable stopper 142s is integrally formed on the outer circumferential surface of the valve stem holder 142. The upper part of the valve disc 130 is disposed in the shaft hole 142b, and the upper part of the valve disc 130 is movable up and down within the shaft hole 142b. A valve-closing spring 147 is disposed between the upper wall portion 142a of the valve stem holder 142 and the step portion 134 of the valve disc 130. The valve-closing spring 147 is a coil spring that presses the valve disc 130 toward the valve seat 118. A female screw 142c is provided on the inner peripheral surface of the valve stem holder 142. The movable stopper 142s is fixed to the rotor 141.

[0109] The guide bush 143 has a base 143a and a support portion 143b. The base 143a and the support portion 143b are cylindrical. The base 143a is press-fit into the fitting hole 111a of the main body member 111. The guide bush 143 is fixed to the valve body 110. The support portion 143b is coaxially connected to the upper end of the base 143a. A male thread 143c is provided on the outer peripheral surface of the support portion 143b. The male thread 143c is threadedly engaged with the female thread 142c of the valve stem holder 142. The valve stem holder 142 may have a male thread, and the guide bush 143 may have a male thread. The shaft portion 131 of the valve element 130 is disposed inside the guide bush 143. The guide bush 143 supports the valve element 130 so that it can move in the direction of the axis L. The guide bush 143 is a guide member.

[0110] The stopper member 144 has a cylindrical shape. The stopper member 144 is fixed to the lower end of the support portion 143b of the guide bush 143. A fixed stopper 144s is integrally provided on the outer circumferential surface of the stopper member 144. The fixed stopper 144s is fixed to the valve body 110.

[0111] The retaining member 145 has a fixed portion 145a and a flange portion 145b. The fixed portion 145a has a stepped cylindrical shape. The upper portion of the valve body 130 is disposed inside the fixed portion 145a. The fixed portion 145a is joined to the upper portion of the valve body 130. The flange portion 145b is connected to the lower end of the fixed portion 145a.

[0112] The stator 160 has a cylindrical shape and includes an A-phase stack 161 and a B-phase stack 162.

[0113] The A-phase stack 161 has a plurality of claw-pole-type pole teeth and an A-phase coil 161c. The B-phase stack 162 has a plurality of claw-pole-type pole teeth and a B-phase coil 162c. An A-phase current Ia flows through the A-phase coil 161c, and a B-phase current Ib flows through the B-phase coil 162c. The stator 160 has the same configuration as the stator 60 of the first embodiment.

[0114] The can 120 is disposed inside the stator 160. The rotor 141 is disposed inside the can 120. The stator 160 and the rotor 141 form a stepping motor 166. The stepping motor 166 is connected to an electric valve control device 170. The stepping motor 166 is controlled in the same manner as the stepping motor 66 of the first embodiment.

[0115] When pulses P are cyclically input to the stepping motor 166 in ascending order, the rotor 141 rotates in the closing direction. As the rotor 141 rotates in the closing direction, the rotor 141 and the valve stem holder 142 move downward due to the feed screw action between the female thread 142c of the valve stem holder 142 and the male thread 143c of the guide bush 143. The valve stem holder 142 presses the valve disc 130 downward via the valve closing spring 147. The valve disc 130 moves downward, and the valve portion 133 comes into contact with the valve seat 118. The rotor 141 is in the valve closing position Rc at this time. If the rotor 141 is further rotated in the closing direction from this state, the valve closing spring 147 is compressed, and the rotor 141 and the valve stem holder 142 move further downward. The valve disc 130 does not move downward. When the movable stopper 142s comes into contact with the fixed stopper 144s, the rotation of the rotor 141 in the closing direction is restricted. The rotor 141 is at the reference position Rx. The movable stopper 142s and the fixed stopper 144s form a stopper mechanism 149 that restricts the rotation of the rotor 141 in the closing direction when the rotor 141 is at the reference position Rx.

[0116] When pulses P are cyclically input to the stepping motor 166 in descending order, the rotor 141 rotates in the opening direction. When the rotor 141 rotates in the opening direction from the reference position Rx, the rotor 141 and the valve stem holder 142 move upward due to the feed screw action between the female thread 142c of the valve stem holder 142 and the male thread 143c of the guide bush 143. When the rotor 141 rotates in the opening direction and passes the closed position Rc, the valve stem holder 142 pushes the retaining member 145 upward. The valve disc 130 moves upward together with the retaining member 145, and the valve disc 130 separates from the valve seat 118, opening the valve port 117. In other words, when the rotor 141 is in the closed position Rc, inputting Nc pulses P to the stepping motor 166 to rotate the rotor 141 in the opening direction opens the valve port 117. Nc is set appropriately depending on the configuration of the motor-operated valve device 101. For example, Nc is 1 to 10. At this time, the rotor 141 is in the valve open position Ro. When the rotor 141 further rotates in the opening direction and the valve portion 133 is farthest from the valve port 117, the opening of the valve port 117 becomes maximum. At this time, the rotor 141 is in the fully open position Rz. The number of pulses P required to rotate the rotor 141 from the valve closed position Rc to the fully open position Rz is, for example, 450. In this embodiment, the ascending order is the first order, and the descending order is the second order.

[0117] The motor-operated valve 105 has an open state SO in which the valve port 117 is open, a closed state SC in which the valve port 117 is closed, and a rotation restricted state SR in which rotation of the rotor 141 in the closing direction is restricted. When the rotor 141 is in a fully open position Rz or a position between the fully open position Rz and a closed position Rc, the motor-operated valve 105 is in the open state SO. When the rotor 141 is in a closed position Rc or a position between the closed position Rc and a reference position Rx, the motor-operated valve 105 is in the closed state SC. When the rotor 141 rotates in the closing direction and reaches the reference position Rx, the motor-operated valve 105 enters the rotation restricted state SR.

[0118] In the electric valve 105, the valve port 117, valve seat 118, can 120, valve body 130, rotor 141, valve stem holder 142, guide bush 143, and stator 160 (A-phase stack 161 and B-phase stack 162) each have a central axis that coincides with the axis L.

[0119] The motor-operated valve control device 170 has a substrate 171 on which a plurality of electronic components (not shown) are mounted. The motor-operated valve control device 170 has a non-volatile memory, a communication device, a motor driver 177, and a computer 180. The motor-operated valve control device 170 has the same hardware configuration as the motor-operated valve control device 70 of the first embodiment. The motor-operated valve control device 170 controls the motor-operated valve 105 based on commands from the air conditioner control device 510.

[0120] Computer 180 functions as rotation control unit 181, acquisition unit 182, and detection unit 183 by the CPU executing a program stored in ROM (FIG. 14). Rotation control unit 181, acquisition unit 182, and detection unit 183 function in the same way as rotation control unit 81, acquisition unit 82, and detection unit 83 of the first embodiment.

[0121] The inventors measured the time change of the drive current flowing through the coils (A-phase coil 161c and B-phase coil 162c) when pulses P were input to the stepping motor 166 in ascending order to rotate the rotor 141 in the closing direction. FIG. 15 shows an example of the time change measured chronologically. Each black dot corresponds to a time change. In FIG. 15, the motor-operated valve 105 is in the open state SO before time tc. At time tc, the rotor 141 reaches the closed position Rc, and the motor-operated valve 105 transitions from the open state SO to the closed state SC. Then, at time tx, the rotor 141 reaches the reference position Rx, and the motor-operated valve 105 transitions from the closed state SC to the rotation restricted state SR.

[0122] 15, the change time is long when the motor-operated valve 105 is in the open state SO, and is short when the motor-operated valve 105 is in the closed state SC or the rotation-restricted state SR. This is thought to be because when the motor-operated valve 105 is in the closed state SC or the rotation-restricted state SR, the valve-closing spring 147 is compressed in response to the rotation of the rotor 141 in the closing direction, so the load on the rotor 141 is greater than when the motor-operated valve 105 is in the open state SO. Therefore, the state of the motor-operated valve 105 can be determined based on the change time, which is related to the load on the rotor 141.

[0123] Furthermore, when the motor-operated valve 105 is in the open state SO or the closed state SC, the difference (variation) between the maximum and minimum values ​​of the change time is small, and when the motor-operated valve 105 is in the rotation restricted state SR, the difference between the maximum and minimum values ​​of the change time is large. This is thought to be because, after the rotor 141 rotates in the closing direction and reaches the reference position Rx, the movable stopper 142s repeatedly collides with the fixed stopper 144s, causing the rotor 141 to temporarily rotate in the opening direction. Therefore, the state of the motor-operated valve 105 can be determined based on the change time.

[0124] When power is turned on, the motor-operated valve control device 170 reads the position of the rotor 141 from the nonvolatile memory and sets it as the current position. The motor-operated valve control device 170 stores the position of the rotor 141 immediately before power is cut off in the nonvolatile memory.

[0125] The computer 180 of the motor-operated valve control device 170 executes an initialization operation when it receives an initialization command from the air conditioner control device 510 or when the position of the rotor 141 read from the nonvolatile memory is abnormal.

[0126] Next, a first example of the initialization operation of the motor-operated valve control device 170 will be described with reference to Fig. 16. Fig. 16 shows a flowchart of the first example of the initialization operation.

[0127] The motor-operated valve control device 170 inputs pulses P to the stepping motor 166 (motor driver 177) in ascending order (S310), and supplies a drive current to the coil of the stator 160 to rotate the rotor 141 in the closing direction. The rotor 141 rotates in the closing direction.

[0128] Next, the motor-operated valve control device 170 determines whether the motor-operated valve 105 has transitioned from the open state SO to the closed state SC (S320). Specifically, the motor-operated valve control device 170 acquires a change time Ta of the drive current while inputting pulses P to the stepping motor 166 in ascending order, and compares the change time Ta with a criterion value Tk. The criterion value Tk is set, for example, based on a plurality of change times Ta acquired when the motor-operated valve 105 is in the open state SO and a plurality of change times Ta acquired when the motor-operated valve 105 is in the closed state SC. A single criterion value Tk may be used for the rise time and fall time of the A-phase current Ia and the rise time and fall time of the B-phase current Ib, or individual criterion values ​​Tk may be used.

[0129] When the change time Ta is greater than the determination value Tk, the motor-operated valve control device 170 determines that the motor-operated valve 105 is in the open state SO (N in S320), and returns to step S310.

[0130] When the change time Ta is equal to or less than the determination value Tk, the motor-operated valve control device 170 determines that the motor-operated valve 105 has transitioned to the closed valve state SC (Y in S320), and acquires the position of the rotor 141 at that time as the closed valve position Rc (S330). Alternatively, the motor-operated valve control device 170 may acquire the position of the rotor 141 that is away from the closed valve position Rc in the opening direction by an angle corresponding to Np pulses P as the open valve position Ro. Np is set appropriately depending on the configuration of the motor-operated valve device 101. For example, Np is 1 to 10. The motor-operated valve control device 170 then ends the initialization operation.

[0131] When the initially acquired change time Ta is equal to or less than the judgment value Tk, the motor-operated valve control device 170 determines that the motor-operated valve 105 is in the closed state SC, inputs Nd pulses P to the stepping motor 166 in descending order, and supplies a drive current to the coil of the stator 160 to rotate the rotor 141 in the opening direction. The angle corresponding to the Nd pulses P is greater than the angle from the reference position Rx to the closed position Rc. Nd is set appropriately depending on the configuration of the motor-operated valve device 101. For example, Nd is 100. The rotor 141 rotates in the closing direction, and the motor-operated valve 105 transitions from the closed state SC to the open state SO. The motor-operated valve control device 170 then returns to step S310.

[0132] After the initialization operation is completed, the motor-operated valve control device 170 controls the position of the rotor 141 (i.e., the valve opening) with the closed valve position Rc as position [0]. The motor-operated valve control device 170 increases a number (index) indicating the position of the rotor 141 when pulses P are input to the stepping motor 166 in descending order, and decreases the number when pulses P are input to the stepping motor 166 in ascending order. For example, the open valve position Ro is position [Np]. If the number of pulses P required to rotate the rotor 141 from the closed valve position Rc to the fully open position Rz is 450, the fully open position Rz is position

[450] . Note that the motor-operated valve control device 170 may also control the position of the rotor 141 with the open valve position Ro as position [0].

[0133] In a configuration that employs the example 1 of the initialization operation, the stopper mechanism 149 (the movable stopper 142s and the fixed stopper 144s) may be omitted.

[0134] Next, a second example of the initialization operation of the motor-operated valve control device 170 will be described with reference to Fig. 17. Fig. 17 shows a flowchart of the second example of the initialization operation.

[0135] In the initialization operation example 2, the operations of steps S410, S420, and S430 are the same as the operations of steps S310, S320, and S330 in the initialization operation example 1. A description of the operations of steps S410 to S430 will be omitted.

[0136] The motor-operated valve control device 170 inputs pulses P to the stepping motor 166 (motor driver 177) in ascending order (S440), and supplies a drive current to the coil of the stator 160 for rotating the rotor 141 in the closing direction. The rotor 141 rotates in the closing direction.

[0137] Next, the motor-operated valve control device 170 determines whether the motor-operated valve 105 has transitioned from the closed state SC to the rotation restriction state SR (S450). That is, the motor-operated valve control device 170 determines whether the rotor 141 has reached the reference position Rx. Specifically, the motor-operated valve control device 170 acquires the variation Ba of Ne change times Ta while inputting pulses P to the stepping motor 166 in ascending order, and compares the variation Ba with a judgment value Bh. Ne is set appropriately depending on the configuration of the motor-operated valve device 101. For example, Ne is 10. The variation Ba is, for example, the standard deviation of the multiple change times Ta. The variation Ba may also be the difference between the maximum and minimum values ​​of the multiple change times Ta. The judgment value Bh is set, for example, based on the variation amount Ba of multiple change times Ta obtained when the electric valve 105 is in the open state SO, and the variation amount Ba of multiple change times Ta obtained when the electric valve 105 is in the closed state SC.

[0138] When the variation amount Ba is smaller than the judgment value Bh, the motor-operated valve control device 170 judges that the motor-operated valve 105 is in the valve-closed state SC (N in S450), and returns to step S440.

[0139] When the variation amount Ba is equal to or greater than the reference value Bh, the motor-operated valve control device 170 determines that the motor-operated valve 105 has transitioned to the rotation restricted state SR (Y in S450), and acquires the position of the rotor 141 at that time as the reference position Rx (S460). The motor-operated valve control device 170 also acquires the number Nx of pulses P input until the rotor 141 moves from the valve-closed position Rc to the position of the rotor 141 acquired as the reference position Rx, and determines the number of pulses P required to rotate the rotor 141 from the reference position Rx to the valve-closed position Rc as (Nx - Ne). The motor-operated valve control device 170 then terminates the initialization operation.

[0140] After the initialization operation is completed, the motor-operated valve control device 170 controls the position (valve opening) of the rotor 141, with the reference position Rx set as position [0]. For example, the valve-closed position Rc is position [Nx-Ne], and the valve-opened position Ro is position [Nx-Ne+Np]. If the number of pulses P required to rotate the rotor 141 from the reference position Rx to the fully open position Rz is 500, the fully open position Rz is position

[500] .

[0141] As described above, the motor-operated valve device 101 includes the motor-operated valve 105 and the motor-operated valve control device 170. The motor-operated valve 105 includes the valve body 110 having the valve port 117, the rotor 141, and the stepping motor 166 having coils (A-phase coil 161c and B-phase coil 162c) to which a drive current for rotating the rotor 141 is supplied, and the valve element 130 that moves relative to the valve port 117 when the rotor 141 rotates. The motor-operated valve control device 170 includes a computer 180 that detects the load on the rotor 141 using the change time Ta, which is the time it takes for the drive current flowing through the coil to change from a first current value to a second current value. This allows the motor-operated valve control device 170 to detect the load on the rotor 141 with a relatively simple configuration. Furthermore, the motor-operated valve control device 170 can determine the state of the motor-operated valve 105 based on the load on the rotor 141 (change time Ta).

[0142] The motor-operated valve 105 also has a valve stem holder 142 fixed to the rotor 141 and a guide bush 143 fixed to the valve body 110. The valve stem holder 142 has a female thread 142c, and the guide bush 143 has a male thread 143c that screws into the female thread 142c. When the rotor 141 rotates in the closing direction, the rotor 141 and the valve stem holder 142 move toward the valve port 117, and the valve stem holder 142 presses the valve body 130 via the valve closing spring 147. When the rotor 141 rotates in the opening direction, the rotor 141 and the valve stem holder 142 move away from the valve port 117. The motor-operated valve 105 has an open state SO in which the valve port 117 is open, and a closed state SC in which the valve port 117 is closed. A motor driver 177 is connected to the coil. When pulses P are input in ascending order, the motor driver 177 supplies a drive current to the coil to rotate the rotor 141 in the closing direction. When pulses P are input in descending order, the motor driver 177 supplies a drive current to the coil to rotate the rotor 141 in the opening direction. The computer 180 inputs pulses P to the motor driver 177 in ascending order. While the computer 180 is inputting pulses P in ascending order, the computer 180 determines whether the motor-operated valve 105 has transitioned from the open state SO to the closed state SC based on the load on the rotor 141 (change time Ta). The computer 180 obtains the closed valve position Rc, in which the valve disc 130 contacts the valve seat 118, based on the position of the rotor 141 when it determines that the motor-operated valve 105 has transitioned from the open state SO to the closed state SC. In this manner, the motor-operated valve control device 170 can obtain the closed valve position Rc relatively easily. Furthermore, the motor-operated valve control device 170 can accurately control the position of the rotor 141 based on the closed valve position Rc.

[0143] Furthermore, after the computer 180 determines that the motor-operated valve 105 has transitioned from the open state SO to the closed state SC, it determines whether the motor-operated valve 105 has transitioned from the closed state SC to the rotation restricted state SR, in which rotation of the rotor 141 in the closing direction is restricted, based on the variation Ba in the change time Ta. The computer 180 acquires a reference position Rx, in which rotation of the rotor 141 in the closing direction is restricted, based on the position of the rotor 141 when it determines that the motor-operated valve 105 has transitioned from the closed state SC to the rotation restricted state SR. In this manner, the motor-operated valve control device 170 can acquire the reference position Rx relatively easily. Furthermore, the motor-operated valve control device 170 can accurately control the position of the rotor 141 based on the reference position Rx.

[0144] The motor-operated valve control device 70 of the first embodiment may acquire the valve closed position Rc by performing an initialization operation similar to Example 1 of the initialization operation of the motor-operated valve control device 170 of the second embodiment.

[0145] The motor-operated valve control device 70 of the first embodiment may control the motor driver 77 to supply a drive current to the coil of the stator 60 according to the load of the rotor 41. Specifically, while inputting pulses P to the stepping motor 66, the motor-operated valve control device 70 (computer 80) detects the load of the rotor 41 based on the change time Ta. If the motor-operated valve control device 70 determines that the load of the rotor 41 is large, it increases the target value of the drive current set in the motor driver 77, thereby increasing the drive current supplied by the motor driver 77 to the coil. If the motor-operated valve control device 70 determines that the load of the rotor 41 is small, it decreases the target value of the drive current set in the motor driver 77, thereby decreasing the drive current supplied by the motor driver 77 to the coil. In this manner, the motor-operated valve control device 70 can supply a drive current according to the load of the rotor 41, thereby preventing step-out of the stepping motor 66 due to insufficient drive current and power waste due to excessive drive current.

[0146] In this specification, terms indicating a shape, such as "cylinder" or "column," are also used to refer to members or portions of members that substantially have the shape of the term. For example, a "cylindrical member" includes both a cylindrical member and a substantially cylindrical member. In addition, in this specification, the term "same" can include both the exact same and the substantially same.

[0147] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Any modifications, additions, deletions, or design changes of components made by a person skilled in the art to the above embodiments, or any combinations of features of the embodiments, are also included within the scope of the present invention as long as they do not deviate from the spirit of the present invention.

[0148] (First embodiment) 1... motor-operated valve device, 5... motor-operated valve, 10... valve body, 13... valve port, 20... valve element, 25... valve-opening spring, 30... drive mechanism, 31... drive shaft, 32t... male thread, 35... guide member, 35t... female thread, 41... rotor, 50... planetary gear mechanism, 60... stator, 61c... A-phase coil, 62c... B-phase coil, 66... ​​stepping motor, 70... motor-operated valve control device, 77... motor driver, 80... computer, 500... air conditioner, 510... air conditioner control device (Second embodiment) 101... motor-operated valve device, 105... motor-operated valve, 110... valve body, 117... valve port, 118... valve seat, 130... valve body, 141... rotor, 142... valve stem holder, 142c... female thread, 143... guide bush, 143c... male thread, 147... valve closing spring, 149... stopper mechanism, 160... stator, 161c... A-phase coil, 162c... B-phase coil, 166... ​​stepping motor, 170... motor-operated valve control device, 177... motor driver, 180... computer

Claims

1. An electric valve control device that controls an electric valve having a valve body with a valve port, a stepping motor having a rotor and a coil to which a drive current for rotating the rotor is supplied, and a valve body that moves relative to the valve port when the rotor rotates, characterized by having a processing device that detects the load on the rotor using the change time it takes for the drive current flowing through the coil to change from a first current value to a second current value.

2. The motor-operated valve has a drive shaft, a gear mechanism that transmits the rotation of the rotor to the drive shaft, and a guide member fixed to the valve body, wherein the guide member has a female thread and the drive shaft has a male thread that is screwed into the female thread, or the drive shaft has a female thread and the guide member has a male thread that is screwed into the female thread, the motor-operated valve has a transmission state in which the rotation of the rotor is transmitted to the drive shaft and a play state in which the rotation of the rotor is not transmitted to the drive shaft, when the drive shaft rotates, the valve body moves relative to the valve orifice, a motor driver is connected to the coil, when pulses are input in a first sequence, the motor driver supplies the drive current to the coil to rotate the rotor in a first direction, and when pulses are input in a second sequence, the motor driver supplies the drive current to the coil to rotate the rotor in a second direction, the processing device inputs pulses to the motor driver in the first sequence, and subsequently inputs pulses to the motor driver in the second sequence, 2. The motor-operated valve control device according to claim 1, wherein, when pulses are being input in the second sequence, it is determined whether the motor-operated valve has transitioned from the idle state to the transmission state based on a load on the rotor, and when it is determined that the motor-operated valve has transitioned from the idle state to the transmission state, a correction number is obtained based on the number of pulses input in the second sequence.

3. The electric valve control device according to claim 2, wherein, when the number of pulses input to the motor driver to rotate the rotor from the current position to the target position is M and the correction number is C, the processing device (i) inputs M pulses to the motor driver when rotating the rotor from the current position to the target position in the same direction as the previous rotation direction, and (ii) inputs (C+M) pulses to the motor driver when rotating the rotor from the current position to the target position in the opposite direction to the previous rotation direction.

4. The motor-operated valve has a holder fixed to the rotor and a guide member fixed to the valve body, wherein the holder has a female thread and the guide member has a male thread that screws into the female thread, or the guide member has a female thread and the holder has a male thread that screws into the female thread, when the rotor rotates in the closing direction, the rotor and the holder move in a direction approaching the valve orifice, and the holder presses the valve body via a valve-closing spring, when the rotor rotates in the opening direction, the rotor and the holder move in a direction away from the valve orifice, the motor-operated valve has an open state in which the valve orifice is open and a closed state in which the valve orifice is closed, a motor driver is connected to the coil, when pulses are input in a first sequence, the motor driver supplies the drive current to the coil for rotating the rotor in the closing direction, and when pulses are input in a second sequence, the motor driver supplies the drive current to the coil for rotating the rotor in the opening direction, the processing device inputs pulses to the motor driver in the first sequence, 2. The motor-operated valve control device according to claim 1, wherein when pulses are input in the first sequence, it is determined whether the motor-operated valve has transitioned from the open state to the closed state based on a load on the rotor, and a closed valve position in which the valve body contacts a valve seat surrounding the valve orifice is obtained based on a position of the rotor when it is determined that the motor-operated valve has transitioned from the open state to the closed state.

5. The electric valve control device according to claim 4, wherein the processing device, after determining that the electric valve has transitioned from the open valve state to the closed valve state, determines whether the electric valve has transitioned from the closed valve state to a rotation restriction state in which rotation of the rotor in the closing direction is restricted based on the amount of variation in the change time, and obtains a reference position in which rotation of the rotor in the closing direction is restricted based on the position of the rotor when it is determined that the electric valve has transitioned from the closed valve state to the rotation restriction state.

6. The motor-operated valve control device according to claim 1, wherein a motor driver is connected to the coil, the motor driver supplies the drive current to the coil when a pulse is input, and the processing device increases the drive current when it determines that the load on the rotor is large, and decreases the drive current when it determines that the load on the rotor is small.

7. A motor-operated valve device comprising the motor-operated valve and the motor-operated valve control device according to any one of claims 1 to 6.

8. A load detection method for an electrically operated valve having a valve body with a valve port, a stepping motor having a rotor and a coil to which a drive current for rotating the rotor is supplied, and a valve element that moves relative to the valve port when the rotor rotates, characterized in that the load on the rotor is detected using the time it takes for the drive current flowing through the coil to change from a first current value to a second current value.

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