Electric valve control device, electric valve device, and electric valve control method

Abstract

[Problem] To provide an electric valve control device, an electric valve device, and an electric valve control method that are capable of inhibiting desynchronization of a stepping motor and deterioration of durability of an electric valve. [Solution] A computer included in an electric valve control device 70 inputs a plurality of pulses to a stepping motor 66 to cause a rotor 41 of the stepping motor 66 to rotate. The computer sets the input speed of the last one or more pulses among the plurality of pulses to be lower than the input speed of pulses preceding the last one or more pulses.

Description

Motor-operated valve control device, motor-operated valve device, and motor-operated valve control 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 controlling an electric valve.

[0002] A conventional motor-operated valve is disclosed in Patent Document 1. The motor-operated valve in Patent Document 1 has a stepping motor, a reduction mechanism, a drive shaft, a bearing member, and a valve body. The stepping motor has a rotor and a stator. The rotor rotates when a pulse is input to the stepping motor. Specifically, the rotor rotates when a drive current corresponding to the pulse is supplied to the stator. The rotation of the rotor is transmitted to the drive shaft by the reduction mechanism. The drive shaft has a male thread. The bearing member has a female thread into which the male thread is threaded. When the drive shaft rotates, the drive shaft moves axially. The valve body moves axially as the drive shaft moves.

[0003] JP 2012-197849 A

[0004] When a pulse is input to a stepping motor, the rotor rotates, and when the pulse input is stopped, the rotor stops. When the pulse input is stopped, the rotor does not stop immediately and may rotate too much. This causes the stepping motor to lose synchronization. By constantly supplying a relatively large drive current corresponding to the pulse to the stator, the rotor can be prevented from rotating too much, but this can cause wear to parts such as the gears and drive shaft of the reduction mechanism. This reduces the durability of the motor-operated valve.

[0005] Therefore, an object of the present invention is to provide an electric valve control device, an electric valve device, and a method for controlling an electric valve that can suppress step-out of a stepping motor and a decrease in the durability of an electric valve.

[0006] The present inventors conducted extensive research into stepping motors using multiple motor-operated valves. As a result, the inventors discovered the following (i) to (iii), leading to the present invention: (i) When multiple pulses are input to a stepping motor, or when the pulse input rate is increased while multiple pulses are being input, the rotor's angular velocity increases toward a peak value corresponding to the pulse input rate. (ii) If the rotor's angular velocity does not reach its peak value before the last pulse of the multiple pulses is input, the stepping motor is likely to step out of step. However, if the rotor's angular velocity reaches its peak value before the last pulse of the multiple pulses is input, the stepping motor is less likely to step out of step. (iii) If the pulse input rate is relatively low, the stepping motor is less likely to step out of step.

[0007] 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 stepping motor with a rotor and a stator, and a valve body that moves relative to the valve port when the rotor rotates, wherein the electric valve control device has a processing device that inputs multiple pulses to the stepping motor to rotate the rotor, and reduces the input speed of the last pulse of the multiple pulses below the input speed of the pulses before the last pulse.

[0008] In order to achieve the above object, another 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 stepping motor with a rotor and a stator, and a valve element that moves relative to the valve port when the rotor rotates, the electric valve control device having a processing device that inputs a plurality of pulses to the stepping motor to rotate the rotor, and that sets the input speed of at least one last pulse of the plurality of pulses to be slower than the input speed of pulses before the at least one last pulse. The term "at least one last pulse of the plurality of pulses" includes both the last pulse of the plurality of pulses and a series of pulses including the last pulse of the plurality of pulses.

[0009] In the present invention, it is preferable that when the processing device determines that the angular velocity of the rotor does not reach a peak value corresponding to the input speed of the pulses before the final pulse of the plurality of pulses is input, the processing device sets the input speed of the final at least one pulse (second speed) to be lower than the input speed of the pulses before the final at least one pulse (first speed), and when the processing device determines that the angular velocity of the rotor will reach the peak value before the final pulse is input, the processing device sets the input speed of the plurality of pulses (first speed) to be constant.

[0010] In the present invention, it is preferable that, when the number of pulses input to the stepping motor to rotate the rotor from the current position to the target position is M, the number of pulses necessary for the angular velocity of the rotor to reach a first peak value corresponding to the first speed from 0 when pulses are input to the stepping motor at a first speed is N, and S is a natural number greater than or equal to 1 and less than N, the processing device acquires M when rotating the rotor from the current position to the target position, and when M>N, inputs M pulses to the stepping motor at the first speed, when M≦N and M>S, inputs (M−S) pulses to the stepping motor at the first speed, and subsequently inputs S pulses to the stepping motor at a second speed lower than the first speed, and when M≦S, inputs M pulses to the stepping motor at the second speed.

[0011] In the present invention, it is preferable that, when the number of pulses input to the stepping motor to rotate the rotor from the current position to the target position is M, and the number of pulses required for the angular velocity of the rotor to reach a first peak value corresponding to the first speed when pulses are input to the stepping motor at a first speed is N, the processing device acquires M when rotating the rotor from the current position to the target position, and when M>N, inputs M pulses to the stepping motor at the first speed, and when M≦N, inputs M pulses to the stepping motor at a second speed lower than the first speed.

[0012] In the present invention, it is preferable that the number of pulses required for the angular velocity of the rotor to reach the first peak value from 0 is set based on the back electromotive force generated in the stator when pulses are input to the stepping motor at the first speed to rotate the rotor.

[0013] In the present invention, it is preferable that a drive current corresponding to pulses is supplied to the stator, the drive current being a current that alternately changes between a first current value and a second current value, and the number of pulses required for the angular velocity of the rotor to reach the first peak value is set based on a change time required for the drive current flowing through the stator to change from the first current value to the second current value when pulses are input to the stepping motor at the first speed to rotate the rotor.

[0014] In the present invention, it is preferable that a drive current corresponding to pulses is supplied to the stator, the drive current being a current that alternates between a first current value and a second current value, and the number of pulses input to the stepping motor to rotate the rotor from the current position to the target position is M, when the processing device rotates the rotor from the current position to the target position, acquires M, inputs (M-1) pulses to the stepping motor at a first speed, and determines whether the angular velocity of the rotor reaches the peak value before the Mth pulse is input based on the change time for the drive current corresponding to the (M-1)th pulse flowing through the stator to change from the first current value to the second current value, and when it is determined that the angular velocity of the rotor has reached the peak value, inputs the Mth pulse to the stepping motor at the first speed, and when it is determined that the angular velocity of the rotor has not reached the peak value, inputs the Mth pulse to the stepping motor at a second speed lower than the first speed.

[0015] 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.

[0016] In order to achieve the above object, another aspect of the present invention provides a control method for an electric valve having a valve body with a valve port, a stepping motor with a rotor and a stator, and a valve body that moves relative to the valve port when the rotor rotates, characterized in that a plurality of pulses are input to the stepping motor to rotate the rotor, and the input speed of the last pulse of the plurality of pulses is set lower than the input speed of the pulses before the last pulse.

[0017] In order to achieve the above object, another aspect of the present invention provides a control method for an electric valve having a valve body with a valve port, a stepping motor with a rotor and a stator, and a valve body that moves relative to the valve port when the rotor rotates, the control method comprising inputting a plurality of pulses to the stepping motor to rotate the rotor, and setting the input speed of at least one final pulse of the plurality of pulses to be slower than the input speed of a pulse before the at least one final pulse.

[0018] In the present invention, when it is determined that the angular velocity of the rotor does not reach a peak value corresponding to the input speed of the pulses before the final pulse of the plurality of pulses is input, it is preferable that the input speed of the final at least one pulse is made lower than the input speed of the pulses before the final at least one pulse, and when it is determined that the angular velocity of the rotor reaches the peak value before the final pulse is input, the input speed of the plurality of pulses is made constant.

[0019] According to the present invention, a rotor is rotated by inputting multiple pulses to a stepping motor. The input speed of at least one final pulse among the multiple pulses is set lower than the input speed of the pulses preceding the at least one final pulse. This configuration suppresses an increase in the angular velocity of the rotor during the period in which the at least one final pulse is input. This prevents the rotor from rotating too quickly without constantly supplying a relatively large drive current to the stator. This prevents step-out of the stepping motor and a decrease in the durability of the motor-operated valve.

[0020] 1 is a block diagram of an air conditioner having a motor-operated valve device; 2 is a cross-sectional view of the motor-operated valve device; 3 is a diagram schematically showing a rotor and a stator of a stepping motor provided in a motor-operated valve of the motor-operated valve device; 4 is a diagram schematically showing a stepping motor, and a computer and a motor driver provided in a motor-operated valve control device of the motor-operated valve device; 5 is a diagram showing an example of the relationship between pulses and step signals and direction signals input to the motor driver; 6 is a diagram showing an example of the correspondence relationship between pulses and A-phase current and B-phase current; 7 is a diagram showing a waveform of a drive current flowing through a stator coil; 8 is a graph showing an example of the relationship between the number of input pulses and the angular velocity of the rotor when the pulse input speed is a first speed; and 9 is a graph showing an example of the relationship between the number of input pulses and the angular velocity of the rotor when the pulse input speed is a second speed. 10 is a flowchart showing a first operation example of the motor-operated valve control device; 11 is a flowchart showing a second operation example of the motor-operated valve control device; 12 is a flowchart showing a third operation example of the motor-operated valve control device; and 13 is a flowchart showing a fourth operation example of the motor-operated valve control device.

[0021] Hereinafter, an electric valve device according to one embodiment of the present invention will be described.

[0022] The motor-operated valve device 1 according to this embodiment is incorporated into, for example, the refrigeration cycle system of an air conditioner 100 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 100 having the motor-operated valve device 1. Fig. 2 shows a cross-sectional view of the motor-operated valve device 1.

[0023] The air conditioner 100 has a compressor 101, a condenser 102, an electric valve device 1 (electric valve 5), and an evaporator 103, which are connected in this order via piping 105. The electric valve device 1 is an expansion valve. The air conditioner 100 has an air conditioner control device 110. The air conditioner control device 110 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 110 uses the electric valve device 1 to control the flow rate of refrigerant flowing through the piping 105.

[0024] The motor-operated valve 5 includes a valve body 10 , a valve element 20 , a drive mechanism 30 , and a stator 60 .

[0025] The valve body 10 includes a housing 11 , a sleeve 14 , a connecting plate 15 , and a can 18 .

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 bearing member 35, a rotor 41, a connecting member 42, a rotor shaft 43, a support member 44, and a planetary gear mechanism 50.

[0033] 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.

[0034] The bearing member 35 has a cylindrical shape. The bearing member 35 is arranged inside the upper part of the peripheral wall portion 11a of the housing 11. The bearing 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 bearing member 35 and the annular flat surface 11c of the peripheral wall portion 11a. The bearing member 35 has a female thread 35t. The female thread 35t is arranged on the lower part of the inner peripheral surface of the bearing member 35. The male thread 32t of the drive shaft 31 is threadedly engaged with the female thread 35t.

[0035] 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. 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.

[0036] 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.

[0037] The planetary gear mechanism 50 is a reduction mechanism that reduces the rotation speed 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.

[0038] 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.

[0039] The output shaft 57 has a cylindrical shape. The lower part of the output shaft 57 is disposed inside the bearing member 35. The output shaft 57 is rotatably supported by the bearing member 35. The upper part of the output shaft 57 is fixed to the bottom part 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.

[0040] 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.

[0041] The stator 60 has a cylindrical shape and includes an A-phase stack 61 and a B-phase stack 62 .

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 a first 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). When the opening of the valve orifice 13 is minimized, a gap may be formed between the valve portion 22 and the valve seat.

[0048] 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 second 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 disc 20, pressed by the valve-opening spring 25, moves upward, and the valve portion 22 moves away from the valve port 13, increasing the opening of the valve port 13. When the valve portion 22 is farthest from the valve port 13, the opening of the valve port 13 is at its maximum.

[0049] The housing 11, valve port 13, sleeve 14, can 18, valve body 20, drive shaft 31, bearing 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.

[0050] 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 110.

[0051] The nonvolatile memory 75 stores data that needs to be retained even when the power is turned off. The nonvolatile memory 75 is, for example, an EEPROM or a flash memory. The nonvolatile memory 75 is a storage unit.

[0052] The communication device 76 is communicably connected to the air conditioner control device 110 via a wired communication bus 120. The air conditioner 100 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 110 wirelessly.

[0053] The motor driver 77 is controlled by the computer 80. The motor driver 77 supplies a driving 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 to the A-phase coil 61c and a B-phase current to the B-phase coil 62c. The motor driver 77 may be provided in the motor-operated valve 5.

[0054] 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 a first 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 in ascending order. When a direction signal corresponding to a second 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 in descending order. FIG. 5 schematically shows an example of the relationship between the pulses P input to the stepping motor 66 and the step signal and direction signal input to the motor driver 77.

[0055] 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 the magnitude of the drive current in the motor driver 77. In this embodiment, the magnitude of the drive current is constant.

[0056] Fig. 6 shows an example of the correspondence between the pulse P and the drive current (A-phase current, B-phase current) supplied by the motor driver 77. In Fig. 6, (+) indicates that an A-phase current is supplied from terminal A1 to terminal A2, or a B-phase current is supplied from terminal B1 to terminal B2, and (-) indicates that an A-phase current is supplied from terminal A2 to terminal A1, or a B-phase current is supplied from terminal B2 to terminal B1.

[0057] The motor driver 77 supplies "+I" and "-I" as drive currents. In response to pulse P[1], "+I" is supplied as the A-phase current and "-I" is supplied as the B-phase current. In response to pulse P[2], "+I" is supplied as the A-phase current and "+I" is supplied as the B-phase current. In response to pulse P[3], "-I" is supplied as the A-phase current and "+I" is supplied as the B-phase current. In response to pulse P[4], "-I" is supplied as the A-phase current and "-I" is supplied as the B-phase current.

[0058] The "+I" and "-I" have the same magnitude but flow in different directions. The magnitude of the drive current (|I|) is, for example, 200 to 600 mA.

[0059] 7 shows a schematic diagram of the waveforms of the drive currents (A-phase current and B-phase current) flowing through the A-phase coil 61c and the B-phase coil 62c of the stator 60 when pulses P are input to the stepping motor 66 in ascending order. The drive current is a rectangular wave that alternates between a first current value (-I) and a second current value (+I). The first current value may be "+I" and the second current value may be "-I."

[0060] In this embodiment, pulses P are input to the stepping motor 66 (i.e., motor driver 77) at a first speed V1 or a second speed V2. The first speed V1 or the second speed V2 is set as the input speed V of the pulses P. The second speed V2 is lower than the first speed V1. For example, the first speed V1 is 100 to 500 pps (pulses per second), and the second speed V2 is 50 to 90% of the first speed V1. 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 microstep manner. The step angle of the stepping motor 66 is, for example, 5 degrees or 7.5 degrees.

[0061] 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.

[0062] The inventors used the motor-operated valve device 1 to study the relationship between the angular velocity of the rotor 41 and step-out of the stepping motor 66 when a pulse P is input to the stepping motor 66 to rotate the rotor 41 .

[0063] The calculated value Cc of the angular velocity of the rotor 41 is the step angle multiplied by the input velocity V of the pulse P. For example, when the step angle is 5 degrees and the input velocity V of the pulse P is 500 pps, the calculated value Cc is 2500 degrees / second. For example, when the step angle is 7.5 degrees and the input velocity V of the pulse P is 300 pps, the calculated value Cc is 2250 degrees / second.

[0064] FIG. 8 schematically illustrates an example of the relationship between the number of input pulses P and the angular velocity of the rotor 41 when pulses P are input to the stepping motor 66 at an input velocity V. The horizontal axis of FIG. 8 represents the number of input pulses P, and the vertical axis represents the angular velocity of the rotor 41. When pulses P are input to the stepping motor 66 at the input velocity V, the angular velocity of the rotor 41 increases from 0, exceeds the calculated value Cc, and reaches a peak value Cp corresponding to the input velocity V. After reaching the peak value Cp, the angular velocity of the rotor 41 decreases and generally stabilizes at or near the calculated value Cc. In other words, the angular velocity of the rotor 41 overshoots. The peak value Cp is the maximum value of the angular velocity of the rotor 41 when pulses P are input to the stepping motor 66 at the input velocity V, and can be, for example, 150 to 250% of the calculated value Cc. The peak value Cp is measured using the motor-operated valve device 1 or calculated by simulation.

[0065] When a pulse P is input to the stepping motor 66, the rotor 41 rotates. Specifically, when the first pulse P is input to the stepping motor 66, the rotor 41 rotates from the current position R0 toward position R1, which is a step angle advance. When the second pulse P is input to the stepping motor 66, the rotor 41 rotates from position R1 toward position R2, which is a step angle advance. When the third pulse P is input to the stepping motor 66, the rotor 41 rotates from position R2 toward position R3, which is a step angle advance. When the fourth pulse P is input to the stepping motor 66, the rotor 41 rotates from position R3 toward position R4, which is a step angle advance. When the fifth or subsequent pulse P is input, the rotor 41 rotates in the same manner.

[0066] The inventors input four pulses P to the stepping motor 66 at a first speed V1. The angular velocity of the rotor 41 increases in response to the input of the first to fourth pulses P ( FIG. 9 ). The angular velocity of the rotor 41 does not reach the first peak value Cp1 corresponding to the first speed V1 before the input of the fourth pulse P, which is the last pulse P. In this case, the angular velocity of the rotor 41 does not decrease to 0 near position R4 after the input of the fourth pulse P, and the rotor 41 may rotate excessively. FIG. 9 is a graph showing an example of the relationship between the number of input pulses P and the angular velocity of the rotor 41 when four pulses P are input to the stepping motor 66 at the first speed V1.

[0067] The inventors also input five pulses P to the stepping motor 66 at a first speed V1. The angular velocity of the rotor 41 increases in response to the input of the first to fourth pulses P, and decreases before the input of the fifth pulse P (not shown). The angular velocity of the rotor 41 reaches a first peak value Cp1 before the input of the fifth pulse P, which is the final pulse P. In this case, after the input of the fifth pulse P, the angular velocity of the rotor 41 decreases to 0 near position R5, and the rotor 41 stops at the correct position.

[0068] In the motor-operated valve device 1 used by the inventors, when pulses P are input to the stepping motor 66 at a first speed V1, the angular velocity of the rotor 41 reaches the first peak value Cp1 after the fourth pulse P is input, and decreases below the first peak value Cp1 before the fifth pulse P is input. Therefore, in the motor-operated valve device 1, when pulses P are input to the stepping motor 66 at the first speed V1, the number of pulses P required for the angular velocity of the rotor 41 to reach the first peak value Cp1 corresponding to the first speed V1 from 0 is four.

[0069] The inventors input three pulses P to the stepping motor 66 at a second speed V2. The second speed V2 is lower than the first speed V1. The angular velocity of the rotor 41 increases in response to the input of the first to third pulses P (not shown). The angular velocity of the rotor 41 does not reach the second peak value Cp2 corresponding to the second speed V2 before the input of the third pulse P, which is the last pulse P. In this case, after the input of the third pulse P, the angular velocity of the rotor 41 decreases to 0 near position R3, and the rotor 41 stops at the correct position.

[0070] The inventors also input four pulses P to the stepping motor 66 at a second speed V2. The angular velocity of the rotor 41 increases in response to the input of the first to third pulses P and decreases before the input of the fourth pulse P. The angular velocity of the rotor 41 reaches the second peak value Cp2 before the input of the fourth pulse P, which is the final pulse P. In this case, after the fourth pulse P is input, the angular velocity of the rotor 41 decreases to 0 near position R4, and the rotor 41 stops at the correct position. FIG. 10 is a graph showing an example of the relationship between the number of input pulses P and the angular velocity of the rotor 41 when four pulses P are input to the stepping motor 66 at the second speed V2.

[0071] In the motor-operated valve device 1 used by the inventors, when pulses P are input to the stepping motor 66 at the second speed V2, the angular velocity of the rotor 41 reaches the second peak value Cp2 after the third pulse P is input, and decreases from the second peak value Cp2 before the fourth pulse P is input. Therefore, in the motor-operated valve device 1, when pulses P are input to the stepping motor 66 at the second speed V2, the number of pulses P required for the angular velocity of the rotor 41 to reach the second peak value Cp2 corresponding to the second speed V2 from 0 is 3.

[0072] When the input speed V of the pulses P is relatively low, the angular speed of the rotor 41 is also relatively low. When the angular speed of the rotor 41 is relatively low, even if the angular speed of the rotor 41 has not reached the peak value Cp by the time the last pulse P is input, the rotor 41 will stop at the correct position after the last pulse P is input.

[0073] These results reveal (i) to (iii). (i) When multiple pulses P are input to the stepping motor 66, the angular velocity of the rotor 41 increases toward a peak value Cp corresponding to the input velocity V of the pulses P. (ii) If the angular velocity of the rotor 41 does not reach the peak value Cp before the last pulse P of the multiple pulses P is input, the stepping motor 66 is likely to lose synchronism. However, if the angular velocity of the rotor 41 reaches the peak value Cp before the last pulse P of the multiple pulses P is input, the stepping motor 66 is unlikely to lose synchronism. (In other words, if the angular velocity of the rotor 41 is increasing when the last pulse P is input, the stepping motor 66 is likely to lose synchronism. However, if the increase in the angular velocity of the rotor 41 is suppressed when the last pulse P is input, the stepping motor 66 is unlikely to lose synchronism.) (iii) If the input velocity V of the pulses P (angular velocity of the rotor 41) is relatively low, the stepping motor 66 is unlikely to lose synchronism.

[0074] Next, an example of the operation executed by the motor-operated valve control device 70 (specifically, the computer 80) will be described with reference to FIGS. 11 to 14. FIG.

[0075] (First Operation Example) FIG. 11 is a flowchart showing a first operation example of the motor-operated valve control device 70.

[0076] The motor-operated valve control device 70 receives a command to change the valve opening, which is the opening of the valve port 13, from the air conditioner control device 110 (S10). The command includes a target valve opening. The motor-operated valve control device 70 calculates a control number M (S20). The control number M is the number of pulses P input to the stepping motor 66 (i.e., the motor driver 77) to rotate the rotor 41 from a current position corresponding to the current valve opening to a target position corresponding to the target valve opening. Note that the motor-operated valve control device 70 obtains the control number M by calculation, but the command to change the valve opening may include the control number M, and the motor-operated valve control device 70 may obtain the control number M from the command.

[0077] The motor-operated valve control device 70 inputs (M-1) pulses P to the stepping motor 66 at a first speed V1 to rotate the rotor 41 (S30). Thereafter, the motor-operated valve control device 70 inputs one pulse P to the stepping motor 66 at a second speed V2 to rotate the rotor 41 (S40). That is, the motor-operated valve control device 70 starts inputting pulses P at the first speed V1 and inputs the final pulse P at the second speed V2. This suppresses the increase in the angular velocity of the rotor 41 in response to the final pulse P, and when the input of M pulses P is complete, the rotor 41 stops at the target position. Note that "inputting one pulse P at the second speed V2" means inputting one pulse P with a period corresponding to the second speed V2. For example, when the first speed V1 is 200 pps and the second speed V2 is 100 pps, (M-1) pulses P with a period of 5 ms are input, followed by one pulse P with a period of 10 ms. A driving current having a length corresponding to the period of the pulse P is supplied to the stator 60 .

[0078] (Second Operation Example) In a configuration for executing the second operation example, the nonvolatile memory 75 stores the number of peak pulses N and the constant S used by the computer 80 .

[0079] The peak pulse number N is the number of pulses P required for the angular velocity of the rotor 41 to reach a first peak value Cp1 corresponding to the first speed V1 from 0 when pulses P are input to the stepping motor 66 at a first speed V1. That is, when N pulses P are input to the stepping motor 66 at the first speed V1 while the rotor 41 is stationary to rotate the rotor 41, the angular velocity of the rotor 41 reaches the first peak value Cp1 from 0, and becomes smaller than the first peak value Cp1 before the (N+1)th pulse P is input. The peak pulse number N is measured using the motor-operated valve device 1 or calculated by simulation. In this embodiment, the peak pulse number N is 4. Note that the first speed V1 is relatively high, and the second speed V2 is relatively low.

[0080] The constant S is a natural number equal to or greater than 1 and equal to or less than N. When the motor-operated valve control device 70 inputs a plurality of pulses P to the stepping motor 66 at a first speed V1 to rotate the rotor 41, and determines that the angular velocity of the rotor 41 does not reach the first peak value Cp1 before the last pulse P of the plurality of pulses P is input, the motor-operated valve control device 70 inputs the last S pulses P at a second speed V2. In this embodiment, the constant S is 2. The constant S is preferably 1 to 5, and is set appropriately depending on the configuration of the motor-operated valve 5.

[0081] FIG. 12 is a flowchart showing a second operation example of the motor-operated valve control device 70.

[0082] The motor-operated valve control device 70 receives a command to change the valve opening degree from the air conditioner control device 110 (S110), and calculates the control number M (S120).

[0083] When the control number M is greater than the peak pulse number N (Yes in S130), the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 will reach a first peak value Cp1 corresponding to the first speed V1 before inputting the last pulse P of the M pulses P, and inputs M pulses P to the stepping motor 66 at the first speed V1 to rotate the rotor 41 (S140). That is, the motor-operated valve control device 70 maintains the first speed V1 from the first to the Mth pulses P until they are input (keeping the input speed of the multiple pulses P constant from start to finish). As a result, the angular velocity of the rotor 41 increases to the first peak value Cp1 corresponding to the first speed V1, then decreases, and generally stabilizes at or near the first calculated value Cc1. The first calculated value Cc1 is the step angle multiplied by the first speed V1. When the input of M pulses P is completed, the rotor 41 stops at the target position.

[0084] When the control number M is less than or equal to the peak pulse number N (No in S130), the electric valve control device 70 determines that the angular velocity of the rotor 41 does not reach the first peak value Cp1 corresponding to the first velocity V1 before the last pulse P of the M pulses P is input.

[0085] When the control number M is greater than the constant S (Yes in S150), the motor-operated valve control device 70 inputs (M-S) pulses P to the stepping motor 66 at a first speed V1 to rotate the rotor 41 (S160). Next, the motor-operated valve control device 70 inputs S pulses P to the stepping motor 66 at a second speed V2 to rotate the rotor 41 (S170). That is, the motor-operated valve control device 70 inputs (M-S) pulses P at the first speed V1, and then inputs the final S pulses P at the second speed V2. This suppresses an increase in the angular velocity of the rotor 41 in response to the final S pulses P, and when the input of M pulses P is complete, the rotor 41 stops at the target position.

[0086] When the control number M is equal to or less than the constant S (No in S150), the motor-operated valve control device 70 inputs M pulses P to the stepping motor 66 at the second speed V2 to rotate the rotor 41 (S180). As a result, the rotor 41 rotates at a relatively low angular velocity, and when the input of M pulses P is completed, the rotor 41 stops at the target position.

[0087] The motor-operated valve device 1 may be configured such that the angular velocity of the rotor 41 reaches the first peak value Cp1 between the (N-1)th and Nth pulses P, and then falls below the first peak value Cp1 before the (N+1)th pulse P is input to the stepping motor 66. Even in this configuration, the motor-operated valve control device 70 performs the same operation as described above. For example, in a configuration in which the angular velocity of the rotor 41 reaches the first peak value Cp1 between the third and fourth pulses P, the number of peak pulses N is set to 4. When the constant S is 2 and the control number M is 3, the motor-operated valve control device 70 inputs the first pulse P to the stepping motor 66 at the first speed V1 and the second and third pulses P at the second speed V2. When the constant S is 2 and the control number M is 4, the electric valve control device 70 inputs the first and second pulses P to the stepping motor 66 at a first speed V1, and inputs the third and fourth pulses P at a second speed V2.

[0088] (Third Operation Example) In a configuration for executing the third operation example, the nonvolatile memory 75 stores the number N of peak pulses used by the computer 80 .

[0089] FIG. 13 is a flowchart showing a third operation example of the motor-operated valve control device 70.

[0090] The motor-operated valve control device 70 receives a command to change the valve opening degree from the air conditioner control device 110 (S210), and calculates the control number M (S220).

[0091] When the control number M is greater than the peak pulse number N (Yes in S230), the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 will reach the first peak value Cp1 corresponding to the first speed V1 before inputting the last pulse P of the M pulses P, and inputs M pulses P to the stepping motor 66 at the first speed V1 to rotate the rotor 41 (S240). As a result, the angular velocity of the rotor 41 increases to the first peak value Cp1 corresponding to the first speed V1, then decreases, and generally stabilizes at or near the first calculated value Cc1. Then, when the input of M pulses P is completed, the rotor 41 stops at the target position. The operations in steps S210 to S240 are the same as the operations in steps S110 to S140 in FIG. 12 .

[0092] When the control number M is equal to or less than the peak pulse number N (No in S230), the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 will not reach the first peak value Cp1 corresponding to the first velocity V1 before the last pulse P of the M pulses P is input, and inputs M pulses P to the stepping motor 66 at the second velocity V2 to rotate the rotor 41 (S250). As a result, the rotor 41 rotates at a relatively low angular velocity, and when the input of M pulses P is completed, the rotor 41 stops at the target position.

[0093] A method for setting the number of peak pulses N used in the second and third operation examples will be described.

[0094] The angular velocity of the rotor 41 is related to the voltage generated in the stator 60 by the rotation of the rotor 41 (the voltage electromagnetically induced in the stator 60). This voltage is called the back electromotive force (back electromotive force). The higher the angular velocity of the rotor 41, the greater the back electromotive force. Therefore, when the angular velocity of the rotor 41 reaches a first peak value Cp1, the back electromotive force becomes the largest. Therefore, pulses P are input to the stepping motor 66 at a first speed V1 while the rotor 41 is stopped, causing the rotor 41 to rotate, and the back electromotive force is observed. The number of pulses P input until the back electromotive force becomes the largest is defined as the peak pulse number N. In this way, the peak pulse number N can be obtained relatively easily.

[0095] Furthermore, the back electromotive force prevents changes in the drive current. Therefore, the angular velocity of the rotor 41 is related to the change time T of the drive current flowing through the stator 60. The drive current is a rectangular wave that alternates between "-I" and "+I." Figure 7 shows an example of the change time T (rise time rt, fall time ft). The larger the back electromotive force, the longer the change time T. Therefore, when the angular velocity of the rotor 41 reaches the first peak value Cp1, the change time T is longest. Therefore, pulses P are input to the stepping motor 66 with the rotor 41 stopped at a first speed V1 to rotate the rotor 41, and the change time T is observed. The number of pulses P input until the change time T is longest is defined as the peak pulse number N. This allows the peak pulse number N to be obtained relatively easily.

[0096] In the first to third operation examples, the motor-operated valve control device 70 may supply the drive current corresponding to the last pulse P for a relatively long period of time. For example, the motor-operated valve control device 70 supplies the drive current corresponding to the last pulse P for 500 ms. In this way, the pole teeth of the stator 60 attract the magnetic poles of the rotor 41 for a longer period of time, and vibration that occurs when the rotor 41 stops at the target position can be suppressed.

[0097] (Fourth Operation Example) In a configuration for executing the fourth operation example, the A-phase coil 61c and the B-phase coil 62c are connected to the ADC of the computer 80. The computer 80 is capable of measuring the change time T (rise time rt and fall time ft) of the drive current flowing through the A-phase coil 61c and the B-phase coil 62c. The change time T is the time it takes for the drive current to change from a first current value to a second current value (from "-I" to "+I" or from "+I" to "-I").

[0098] The nonvolatile memory 75 stores a length determination value Lt and a tilt determination value St used by the computer 80 .

[0099] The length determination value Lt is used to determine the length TL of the change time T. The length determination value Lt is set, for example, based on the length TL corresponding to the first calculated value Cc1 and the first peak value Cp1 of the angular velocity of the rotor 41. The length determination value Lt is preferably longer than the length TL of the change time T corresponding to the first calculated value Cc1.

[0100] The slope determination value St is used to determine the slope TS of the change time T. The slope TS indicates the amount of change in the length TL per unit time (the amount of change in the length TL with respect to the pulse P). The slope determination value St is set, for example, based on the amount of change in the length TL during the time it takes for the angular velocity of the rotor 41 to reach 80% of the first peak value Cp1 from the first calculated value Cc1.

[0101] FIG. 14 is a flowchart showing a fourth operation example of the motor-operated valve control device 70.

[0102] The motor-operated valve control device 70 receives a command to change the valve opening degree from the air conditioner control device 110 (S310), and calculates the control number M (S320).

[0103] The motor-operated valve control device 70 inputs (M-1) pulses P to the stepping motor 66 at a first speed V1 to rotate the rotor 41 (S330). The motor-operated valve control device 70 obtains the change time T (length TL, gradient TS) of the drive current corresponding to the (M-1)th pulse P (S340).

[0104] When the slope TS of the change time T is greater than the slope determination value St (Yes in S350), the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 will not reach the first peak value Cp1 corresponding to the first speed V1 before the Mth pulse P is input, and inputs the Mth pulse P to the stepping motor 66 at the second speed V2 to rotate the rotor 41 (S360). As a result, the increase in the angular velocity of the rotor 41 corresponding to the Mth pulse P is suppressed, and when the input of M pulses P is completed, the rotor 41 stops at the target position.

[0105] When the length TL of the change time T is longer than the length determination value Lt (No in S350, Yes in S370), the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 will not reach the first peak value Cp1 corresponding to the first speed V1 before the Mth pulse P is input, and inputs the Mth pulse P to the stepping motor 66 at the second speed V2 to rotate the rotor 41 (S360). As a result, the increase in the angular velocity of the rotor 41 corresponding to the Mth pulse P is suppressed, and when the input of M pulses P is completed, the rotor 41 stops at the target position.

[0106] When the slope TS of the change time T is equal to or less than the slope determination value St and the length TL of the change time T is equal to or less than the length determination value Lt (No in S350, No in S370), the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 will reach the first peak value Cp1 corresponding to the first speed V1 before the Mth pulse P is input, and inputs the Mth pulse P to the stepping motor 66 at the first speed V1 to rotate the rotor 41 (S380). Then, when the input of M pulses P is completed, the rotor 41 stops at the target position.

[0107] In a fourth operation example, the electric valve control device 70 may use only one of the length TL and the slope TS of the change time T to determine whether the angular velocity of the rotor 41 reaches the first peak value Cp1 corresponding to the first speed V1 before inputting the Mth pulse P.

[0108] 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 the stator 60, 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. The computer 80 inputs multiple pulses P to the stepping motor 66 (i.e., the motor driver 77) to rotate the rotor 41. The computer 80 sets the input speed V of the last S pulses P of the multiple pulses P to be slower than the input speed V of the pulses P before the last S pulses P, where S is a number greater than or equal to 1 and less than the peak pulse number N. This suppresses an increase in the angular velocity of the rotor 41 during the period in which the last S pulses P are input. This prevents the rotor 41 from rotating too much without constantly supplying a relatively large drive current to the stator 60. Therefore, loss of synchronism of the stepping motor 66 and a decrease in the durability of the motor-operated valve 5 can be suppressed.

[0109] Furthermore, when the computer 80 determines that the angular velocity of the rotor 41 does not reach the peak value Cp (first peak value Cp1) corresponding to the input velocity V (first velocity V1) before the last pulse P of the plurality of pulses P is input, the computer 80 sets the input velocity V (second velocity V2) of the last S pulses P of the plurality of pulses P lower than the input velocity V (first velocity V1) of the pulses P before the last S pulses P. When the computer 80 determines that the angular velocity of the rotor 41 reaches the peak value Cp before the last pulse P is input, the computer 80 sets the input velocity V (first velocity V1) of the plurality of pulses P constant from start to finish. In this way, the rotor 41 can be quickly positioned at the target position.

[0110] Furthermore, let M be the number of pulses P input to the stepping motor 66 to rotate the rotor 41 from the current position to the target position, N be the number of pulses P required for the angular velocity of the rotor 41 to reach a first peak value Cp1 corresponding to the first speed V1 from 0 when pulses P are input to the stepping motor 66 at a first speed V1, and S be a natural number greater than or equal to 1 and less than or equal to N. The computer 80 calculates M when rotating the rotor 41 from the current position to the target position. When M>N, the computer 80 inputs M pulses P to the stepping motor 66 at the first speed V1. When M≦N and M>S, the computer 80 inputs (M−S) pulses P to the stepping motor 66 at the first speed V1, and then inputs S pulses P to the stepping motor 66 at a second speed V2 that is lower than the first speed V1. When M≦S, the computer 80 inputs M pulses P to the stepping motor 66 at the second speed V2. In this way, it is possible to prevent the stepping motor 66 from losing synchronization and the durability of the motor-operated valve 5 from decreasing with a relatively simple process.

[0111] Furthermore, the computer 80 calculates M when rotating the rotor 41 from the current position to the target position. When M>N, the computer 80 inputs M pulses P to the stepping motor 66 at a first speed V1. When M≦N, the computer 80 inputs M pulses P to the stepping motor 66 at a second speed V2 that is lower than the first speed V1. By doing this, step-out of the stepping motor 66 and a decrease in the durability of the motor-operated valve 5 can be suppressed with relatively simple processing.

[0112] Furthermore, the computer 80 acquires M when rotating the rotor 41 from the current position to the target position. The computer 80 inputs (M-1) pulses P to the stepping motor 66 at a first speed V1. The computer 80 determines whether the angular velocity of the rotor 41 reaches a first peak value Cp1 before the Mth pulse P is input, based on the change time T of the drive current corresponding to the (M-1)th pulse P flowing through the stator 60. When the computer 80 determines that the angular velocity of the rotor 41 reaches the first peak value Cp1, it inputs the Mth pulse P to the stepping motor 66 at the first speed V1. When the computer 80 determines that the angular velocity of the rotor 41 does not reach the first peak value Cp1, it inputs the Mth pulse P to the stepping motor 66 at a second speed V2 lower than the first speed V1. This allows for relatively simple processing to prevent step-out of the stepping motor 66 and a decrease in the durability of the motor-operated valve 5.

[0113] In addition, the electric valve control device 70 (computer 80) may be configured to determine, for example, based on the angular velocity of the rotor 41 obtained using a sensor, whether the angular velocity of the rotor 41 reaches a peak value Cp corresponding to the input velocity V of the pulses P by the time the last pulse P of the multiple pulses P is input.

[0114] The motor-operated valve control device 70 may also be configured to increase the input speed V of the pulses P while inputting the plurality of pulses P. For example, the motor-operated valve control device 70 starts inputting the plurality of pulses P at a second speed V2, and, halfway through inputting the plurality of pulses P, inputs the pulses P at a first speed V1 that is higher than the second speed V2. In this configuration, when the motor-operated valve control device 70 determines that the angular velocity of the rotor 41 does not reach a first peak value Cp21 corresponding to the first speed V1 to which the second speed V2 has been switched before inputting the last pulse P of the plurality of pulses P, the motor-operated valve control device 70 inputs the last S pulses P at the second speed V2. The first peak value Cp21 may be a value different from the first peak value Cp1 when the angular velocity of the rotor 41 increases from 0.

[0115] The motor-operated valve 5 described above reduces the speed of the rotation of the rotor 41 and transmits it to the drive shaft 31. The motor-operated valve 5 may be a direct-acting motor-operated valve that transmits the rotation of the rotor 41 directly to the drive shaft 31.

[0116] 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.

[0117] 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.

[0118] DESCRIPTION OF SYMBOLS 1...motor-operated valve device, 5...motor-operated valve, 10...valve body, 12...valve chamber, 13...valve port, 18...can, 20...valve body, 30...drive mechanism, 31...drive shaft, 32t...male thread, 35...bearing member, 35t...female thread, 41...rotor, 50...planetary gear mechanism, 60...stator, 61...A-phase stack, 61c...A-phase coil, 62...B-phase stack, 62c...B-phase coil, 66...stepping motor, 70...motor-operated valve control device, 77...motor driver, 80...computer, 100...air conditioner, 110...air conditioner control device

Claims

1. An electric valve control device that controls an electric valve having a valve body with a valve port, a stepping motor with a rotor and a stator, and a valve element that moves relative to the valve port when the rotor rotates, wherein the electric valve control device has a processing device that inputs a plurality of pulses to the stepping motor to rotate the rotor, and reduces the input speed of at least one final pulse of the plurality of pulses below the input speed of a pulse before the at least one final pulse.

2. The motor-operated valve control device according to claim 1, wherein the processing device, when determining that the angular velocity of the rotor does not reach a peak value corresponding to the input rate of the pulses before the last pulse of the plurality of pulses is input, makes the input rate of the last at least one pulse lower than the input rate of the pulses preceding the last at least one pulse, and when determining that the angular velocity of the rotor reaches the peak value before the last pulse is input, makes the input rate of the plurality of pulses constant.

3. The motor-operated valve control device according to claim 2, wherein M is the number of pulses input to the stepping motor to rotate the rotor from the current position to the target position, N is the number of pulses required for the angular velocity of the rotor to reach a first peak value corresponding to the first speed from 0 when pulses are input to the stepping motor at a first speed, and S is a natural number greater than or equal to 1 and less than N, wherein the processing device obtains M when rotating the rotor from the current position to the target position, and when M>N, inputs M pulses to the stepping motor at the first speed, when M≦N and M>S, inputs (M-S) pulses to the stepping motor at the first speed, and subsequently inputs S pulses to the stepping motor at a second speed lower than the first speed, and when M≦S, inputs M pulses to the stepping motor at the second speed.

4. The motor-operated valve control device according to claim 2, wherein M is the number of pulses input to the stepping motor to rotate the rotor from the current position to the target position, and N is the number of pulses required for the angular velocity of the rotor to reach a first peak value corresponding to the first speed from 0 when pulses are input to the stepping motor at a first speed, wherein the processing device acquires M when rotating the rotor from the current position to the target position, and when M>N, inputs M pulses to the stepping motor at the first speed, and when M≦N, inputs M pulses to the stepping motor at a second speed lower than the first speed.

5. An electric valve control device as described in claim 3 or 4, wherein the number of pulses required for the angular velocity of the rotor to reach the first peak value from 0 is set based on the back electromotive force generated in the stator when pulses are input to the stepping motor at the first speed to rotate the rotor.

6. An electric valve control device according to claim 3 or 4, wherein a drive current corresponding to pulses is supplied to the stator, the drive current being a current that alternates between a first current value and a second current value, and the number of pulses required for the angular velocity of the rotor to reach the first peak value from 0 is set based on the time it takes for the drive current flowing through the stator to change from the first current value to the second current value when pulses are input to the stepping motor at the first speed to rotate the rotor.

7. The electric valve control device according to claim 2, wherein a drive current corresponding to pulses is supplied to the stator, the drive current being a current that alternates between a first current value and a second current value, and where M is the number of pulses input to the stepping motor to rotate the rotor from the current position to the target position, the processing device: acquires M when rotating the rotor from the current position to the target position; inputs (M-1) pulses to the stepping motor at a first speed; determines whether the angular velocity of the rotor reaches the peak value before the Mth pulse is input based on the change time of the drive current corresponding to the (M-1)th pulse flowing through the stator until it changes from the first current value to the second current value; when it is determined that the angular velocity of the rotor has reached the peak value, inputs the Mth pulse to the stepping motor at the first speed; and when it is determined that the angular velocity of the rotor has not reached the peak value, inputs the Mth pulse to the stepping motor at a second speed lower than the first speed.

8. A motor-operated valve device comprising the motor-operated valve and the motor-operated valve control device according to claim 1.

9. A control method for an electric valve having a valve body with a valve port, a stepping motor with a rotor and a stator, and a valve element that moves relative to the valve port when the rotor rotates, comprising inputting a plurality of pulses to the stepping motor to rotate the rotor, and setting the input speed of at least one final pulse of the plurality of pulses to be slower than the input speed of a pulse before the at least one final pulse.

10. A control method for an electric valve as set forth in claim 9, wherein, when it is determined that the angular velocity of the rotor does not reach a peak value corresponding to the input rate of the pulses before the final pulse of the plurality of pulses is input, the input rate of the final at least one pulse is made lower than the input rate of the pulses preceding the final at least one pulse, and when it is determined that the angular velocity of the rotor reaches the peak value before the final pulse is input, the input rate of the plurality of pulses is made constant.

Images