Motor-operated valve control device and motor-operated valve control program

Abstract

To actualize the stop of a rotor of a motor valve at a more accurate angle while suppressing power consumption.SOLUTION: A motor valve control device for controlling a motor valve having a stepping motor for rotating a rotor, and a mechanism for changing the rotational movement of the rotor into the axial movement of a valve element includes a rotation control part for specifying a driving current in each phase in accordance with an exciting pattern in each changed-over step, and a rotation instruction part for applying the specified driving current in each phase. Before the rotor being rotated is stopped, the rotation control part specifies the driving current having a higher level than that during rotation in each phase while maintaining the ratio of the specified driving current in each phase in accordance with the exciting pattern, and the rotation instruction part applies the specified driving current having a higher level in each phase to the stepping motor.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an electrically operated valve, and more particularly to a method for controlling a stepping motor. [Background technology]

[0002] An automotive air conditioner is generally configured by arranging a compressor, a condenser, an expansion device, an evaporator, etc. in a refrigeration cycle. The refrigeration cycle is provided with various control valves, such as an expansion valve as an expansion device, to control the flow of the refrigerant. With the recent spread of electric vehicles, etc., motor-operated valves equipped with a stepping motor as a drive unit are becoming widely used.

[0003] Known examples of such motorized valves include one equipped with a magnetic sensor for detecting the valve opening degree (see, for example, Patent Document 1). A valve disc is provided at one end of an actuating rod that rotates with the rotor, and a magnet (sensor magnet) is provided at the other end. A magnetic sensor is provided so as to face the sensor magnet in the axial direction. The rotational motion of the rotor is converted into axial motion of the valve disc by a screw feed mechanism. By detecting changes in magnetic flux accompanying the rotation of the rotor with the magnetic sensor, the rotational angle of the sensor magnet and therefore the axial position of the valve disc can be detected, and the valve opening degree can be calculated.

[0004] A reference position that serves as a control standard is set for the valve element that moves up and down inside the motor-operated valve. When the rotor continues to rotate in the valve closing direction and reaches the reference position, also called the "origin," the rotor's rotation is restricted by a stopper (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-135908 A [Patent Document 2] JP 2020-204344 A Summary of the Invention [Problem to be solved by the invention]

[0006] When a load is applied to the stepping motor due to sliding inside the mechanism, a delay occurs in the rotation of the rotor. This delay creates an error in the rotation angle and reduces the accuracy of the valve opening when the rotor is stopped.

[0007] One way to prevent the rotor from rotating slowly is to increase the level of the drive current applied to the stepping motor, but this has the problem of increasing power consumption when a large drive current is continuously applied.

[0008] A primary object of the present invention is to provide a technique for stopping the rotor of a motor-operated valve at a more accurate angle while suppressing power consumption. [Means for solving the problem]

[0009] An electric valve control device in one aspect of the present invention is an electric valve control device that controls an electric valve having a stepping motor that rotates a rotor by a drive current applied to each phase based on an excitation pattern corresponding to a step, and a mechanism that changes the rotational motion of the rotor into axial motion of a valve body, and is equipped with a rotation control unit that sequentially switches steps when rotating the rotor, and for each switched step, specifies the drive current for each phase according to the excitation pattern corresponding to the step, and a rotation instruction unit that applies the drive current for each phase specified by the rotation control unit to the stepping motor, and before the rotating rotor stops, the rotation control unit specifies a higher level of drive current for each phase than during rotation while maintaining the ratio of the drive current for each phase specified according to the excitation pattern, and the rotation instruction unit applies the higher level of drive current for each phase specified by the rotation control unit to the stepping motor.

[0010] In one aspect of the present invention, an electric valve control program causes a computer that controls an electric valve having a stepping motor that rotates a rotor by a drive current applied to each phase based on an excitation pattern corresponding to a step, and a mechanism that changes the rotational motion of the rotor into axial motion of a valve body to perform a rotation control function that sequentially switches steps when rotating the rotor, and for each switched step, specifies a drive current for each phase according to the excitation pattern associated with that step, and a rotation instruction function that applies the drive current for each phase specified by the rotation control function to the stepping motor, and before the rotating rotor stops, the rotation control function specifies for each phase a drive current of a higher level than during rotation while maintaining the ratio of the drive current for each phase specified according to the excitation pattern, and the rotation instruction function applies the high level drive current for each phase specified by the rotation control function to the stepping motor. Effect of the Invention

[0011] According to the present invention, it is possible to stop the rotor of the motor-operated valve at a more accurate angle while suppressing power consumption. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view illustrating a motor-operated valve according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of a stator and its surroundings. [Diagram 3] FIG. 2 is a diagram illustrating a configuration of a rotor. [Figure 4] 3 is a schematic diagram showing the relationship between a magnetic sensor, a sensor magnet, and magnetic lines of force generated from the sensor magnet; FIG. [Diagram 5] FIG. [Figure 6] 11 is a graph showing the relationship between a sensor value and a sensing angle of a sensor magnet. [Figure 7] 1 is a graph showing the relationship between the angle value (duty ratio) and the step. [Figure 8] FIG. 4 is a schematic diagram of a range of movement of a rotor. [Figure 9] FIG. 11 is a transition diagram of an excitation pattern. [Figure 10] Fig. 10(A) is a diagram showing the relationship between steps and an ideal rotor angle, Fig. 10(B) is a diagram showing the relationship between steps and an actual rotor angle according to the conventional technology, and Fig. 10(C) is a diagram showing the relationship between steps and an actual rotor angle according to the embodiment. [Figure 11] FIG. 4 is a diagram showing changes in drive current value and rotor angle. [Figure 12] FIG. 2 is a functional block diagram of the motor-operated valve control device. [Figure 13] 4 is a flowchart showing a process of the motor-operated valve control device. [Figure 14] Fig. 14(A) is a diagram showing the relationship between steps and rotor angles in a modified example, and Fig. 14(B) is a diagram showing the relationship between steps and rotor angles in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, for convenience, the positional relationship of each structure may be expressed based on the illustrated state. In addition, in the following embodiment and its modified examples, substantially the same components are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0014] FIG. 1 is a cross-sectional view illustrating a motor-operated valve according to an embodiment. The motor-operated valve 1 is applied to a refrigeration cycle of an automobile air conditioner (not shown). This refrigeration cycle includes a compressor that compresses the circulating refrigerant, a condenser that condenses the compressed refrigerant, an expansion valve that throttles and expands the condensed refrigerant and sends it out in the form of mist, and an evaporator that evaporates the mist of refrigerant and cools the air inside the vehicle cabin with the latent heat of evaporation. The motor-operated valve 1 functions as an expansion valve for the refrigeration cycle.

[0015] The motor-operated valve 1 is constructed by assembling a valve body 2 and a motor unit 3. The valve body 2 has a body 5 that houses a valve portion. The body 5 functions as a "valve body." The body 5 is constructed by assembling a first body 6 and a second body 8 coaxially. Both the first body 6 and the second body 8 are made of stainless steel (hereinafter referred to as "SUS"). Since the second body 8 is provided with a valve seat 24, a material with excellent wear resistance is selected. The first body 6 has better weldability than the second body 8, and the second body 8 has better workability than the first body 6.

[0016] The first body 6 is a stepped cylinder whose outer diameter tapers stepwise downward. The outer diameter of the upper end of the first body 6 is slightly tapered, forming a locking portion 52 with a step. A male thread 10 is formed on the outer peripheral surface of the lower part of the first body 6 for assembling the motor-operated valve 1 to a piping body (not shown). The piping body is connected to piping extending from the condenser side and piping connected to the evaporator, but the details thereof will not be described. A seal receiving portion 12 consisting of an annular groove is formed on the outer peripheral surface of the first body 6 slightly above the male thread 10, and a seal ring 14 (O-ring) is fitted into it.

[0017] The first body 6 has a circular hole-shaped recessed fitting portion 16 at its lower portion. The second body 8 has a bottomed cylindrical shape, and its upper portion is press-fitted into the recessed fitting portion 16. A seal accommodating portion 18 consisting of an annular groove is formed on the outer peripheral surface of the lower portion of the second body 8, and a seal ring 20 is fitted into the seal accommodating portion 18. A valve hole 22 is provided so as to penetrate the bottom portion of the second body 8 in the axial direction, and a valve seat 24 is formed at the upper end opening of the valve hole 22. An inlet port 26 is provided at the side of the second body 8, and an outlet port 28 is provided at the lower portion. A valve chamber 30 is formed inside the first body 6 and the second body 8. The inlet port 26 and the outlet port 28 are in communication with each other via the valve chamber 30.

[0018] An actuating rod 32 extending from the rotor 60 of the motor unit 3 is inserted into the inside of the body 5. The actuating rod 32 passes through the valve chamber 30. The actuating rod 32 is obtained by cutting a bar made of a non-magnetic metal, and a needle-shaped valve element 34 is provided integrally at its lower part. The valve element 34 is attached to and detached from the valve seat 24 from the valve chamber 30 side to open and close the valve portion.

[0019] A guide member 36 is erected at the center of the upper part of the first body 6. The guide member 36 is obtained by cutting a tube material made of a non-magnetic metal into a stepped cylindrical shape, and a male thread 38 is formed on the outer circumferential surface of the axial center part. The lower end part of the guide member 36 has a large diameter, and the large diameter part 40 is press-fitted into the upper center of the first body 6 and fixed coaxially. The guide member 36 supports the operating rod 32 axially slidably with its inner circumferential surface, and supports the rotating shaft 62 of the rotor 60 rotatably and slidably with its outer circumferential surface.

[0020] A spring receiver 42 is provided on the operating rod 32 slightly above the valve body 34, and a spring receiver 44 is also provided on the bottom of the guide member 36. A spring 46 (functioning as a "biasing member") is interposed between the spring receivers 42, 44 to bias the valve body 34 in the valve closing direction.

[0021] On the other hand, the motor unit 3 is configured as a three-phase stepping motor including a rotor 60 and a stator 64. The motor unit 3 has a cylindrical can 66 with a bottom, with the rotor 60 disposed inside the can 66 and the stator 64 disposed outside the can 66. The can 66 is a cylindrical member with a bottom that covers the space in which the valve body 34 and its drive mechanism are disposed and contains the rotor 60, and defines an inner pressure space (internal space) where the pressure of the refrigerant acts and an outer non-pressurized space (external space) where the pressure of the refrigerant does not act.

[0022] The can 66 is made of a non-magnetic metal (SUS in this embodiment), and is assembled coaxially with its lower portion being fitted onto the upper end of the first body 6. The amount of insertion of the can 66 is regulated by engaging the lower end with the engaging portion 52. The body 5 and the can 66 are fixed and sealed by applying a full circumference weld (not shown) along the boundary between the lower end of the can 66 and the first body 6. The space surrounded by the body 5 and the can 66 forms the above-mentioned pressure space.

[0023] The stator 64 is configured by arranging a plurality of salient poles at equal intervals on the inner periphery of the laminated core 70. The laminated core 70 is configured by laminating annular cores in the axial direction. A bobbin 74 with a coil 73 (electromagnetic coil) attached thereto is attached to each salient pole. The coil 73 and the bobbin 74 form a "coil unit 75." In this embodiment, the motor unit has three coil units 75 for supplying three-phase current, which are provided at intervals of 120 degrees with respect to the central axis of the laminated core 70 (described in detail later).

[0024] The stator 64 is provided integrally with a case 76 of the motor unit 3. That is, the case 76 is obtained by injection molding (also called "insert molding" or "mold molding") of a corrosion-resistant resin material. The stator 64 is covered with the molded resin formed by the injection molding. The case 76 is made of the molded resin. Hereinafter, the molded product of the stator 64 and the case 76 is also called a "stator unit 78."

[0025] The stator unit 78 has a hollow structure, and is assembled to the body 5 while the can 66 is coaxially inserted therethrough. A seal receiving portion 80 consisting of an annular groove is formed on the outer peripheral surface of the first body 6 slightly below the locking portion 52, and a seal ring 82 (O-ring) is fitted into the seal receiving portion 80. The seal ring 82 is interposed between the upper outer peripheral surface of the first body 6 and the lower inner peripheral surface of the case 76, thereby preventing the outside atmosphere (water, etc.) from entering the gap between the can 66 and the stator 64.

[0026] The rotor 60 includes a cylindrical rotor core 102 attached to the rotating shaft 62, a rotor magnet 104 provided on the outer circumferential surface of the rotor core 102, and a sensor magnet 106 provided on the upper end surface of the rotor core 102. The rotor core 102 is attached to the rotating shaft 62. The rotor magnet 104 is magnetized (magnetized) into multiple poles in its circumferential direction. The sensor magnet 106 is also magnetized (magnetized) into multiple poles. The rotor magnet 104 and the sensor magnet 106 are obtained by magnetizing a magnet portion integrally molded with the rotor core 102 in a post-process, the details of which will be described later.

[0027] The rotating shaft 62 is a cylindrical shaft with a bottom, and is fitted onto the guide member 36 with its open end facing downward. A female thread 108 is formed on the inner peripheral surface of the lower part of the rotating shaft 62, and meshes with the male thread 38 of the guide member 36. A screw feed mechanism 109 formed by these threads converts the rotational motion of the rotor 60 into axial motion of the operating rod 32. This causes the valve element 34 to move (rise and fall) in the axial direction, that is, in the opening and closing direction of the valve portion.

[0028] The upper part of the actuation rod 32 is reduced in diameter, and the reduced diameter part 110 penetrates the bottom part 112 of the rotary shaft 62. An annular stopper 114 is fixed to the tip part of the reduced diameter part 110. Meanwhile, a spring 116 that urges the actuation rod 32 downward (i.e., in the valve closing direction) is interposed between the base end of the reduced diameter part 110 and the bottom part 112. With this configuration, when the valve is opened, the actuation rod 32 is displaced integrally with the rotor 60 in such a manner that the stopper 114 is engaged with the bottom part 112. Meanwhile, when the valve is closed, the spring 116 is compressed by the reaction force that the valve body 34 receives from the valve seat 24. The elastic reaction force of the spring 116 at this time can press the valve body 34 against the valve seat 24, improving the seating performance (valve closing performance) of the valve body 34.

[0029] The motor unit 3 has a circuit board 118 on the outside of the can 66. The circuit board 118 is fixed inside the case 76. In this embodiment, various circuits functioning as a control unit and a communication unit are mounted on the lower surface of the circuit board 118. Specifically, a drive circuit for driving the motor, a control circuit (microcomputer) for outputting a control signal to the drive circuit, a communication circuit for the control circuit to communicate with an external device or an adjustment device, a power supply circuit for supplying power to each circuit and the motor (coil), etc. are mounted. The upper end of the case 76 is closed by a lid 77. The circuit board 118 is disposed in the space below the lid 77 of the case 76.

[0030] A magnetic sensor 119 is provided on the surface of the circuit board 118 facing the sensor magnet 106. The magnetic sensor 119 faces the sensor magnet 106 in the axial direction via the bottom end wall of the can 66. The magnetic flux generated by the sensor magnet 106 changes as the rotor 60 rotates. The magnetic sensor 119 detects the amount of displacement of the rotor 60 (the rotation angle of the rotor 60 in this embodiment) by detecting this change in magnetic flux. The control unit calculates the axial position of the valve body 34 and therefore the valve opening degree based on the amount of displacement of the rotor 60.

[0031] A pair of terminals 117 connected to the coil 73 extend from each bobbin 74 and are connected to a circuit board 118. A power supply terminal, a ground terminal, and a communication terminal (collectively referred to as "connection terminals 81") extend from the circuit board 118 and are each drawn out to the outside through a side wall of the case 76. A connector portion 79 is integrally provided on the side of the case 76, and the connection terminals 81 are arranged inside the connector portion 79.

[0032] A stopper 90 is formed below the rotor 60. As shown in Patent Document 2, the configuration of the stopper 90 is known. When the operating rod 32 reaches the valve-closed position, an elastic reaction force is applied to the rotor 60 by the spring 116, and the valve is stably maintained closed. Eventually, the stopper 90 comes into contact with a protrusion (locking portion) (not shown) formed as part of the guide member 36, completely restricting the rotation of the rotor 60 in the valve-closed direction. Hereinafter, the step when the stopper 90 comes into contact with the protrusion is referred to as the "origin" of the step. In this embodiment, the valve body 34 is in the "reference position" at the origin of the step.

[0033] Fig. 2 is a diagram showing the configuration of the stator 64 and its surroundings. Fig. 2(A) corresponds to the cross section seen from the arrow AA in Fig. 1, and is a cross section of the stator unit 78. Fig. 2(B) shows only the stator 64 (before resin molding). For reference, Fig. 2(A) also shows the can 66 and the rotor 60 (see the two-dot chain line).

[0034] Since the motor unit 3 is a three-phase motor, as shown in FIG. 2A, coil units 75 are provided at equal intervals around the axis L of the rotor 60. As also shown in FIG. 2B, slots 120a to 120c (collectively referred to as "slots 120" when no particular distinction is made) are provided at intervals of 120 degrees around the axis L on the inner periphery of the laminated core 70. In each slot 120, salient poles 122a to 122c (collectively referred to as "salient poles 122") protruding radially inward from the center are formed, and a U-phase coil 73a, a V-phase coil 73b, and a W-phase coil 73c (collectively referred to as "coils 73") are respectively assembled therein. Slits 124 having a U-shaped cross section are also formed between adjacent slots 120 to optimize the magnetic path.

[0035] The rotor magnet 104 faces the salient poles 122a to 122c via the can 66. In this embodiment, as shown in Fig. 2(A), the rotor magnet 104 is magnetized to have ten poles in the male thread, but the number of poles can be set appropriately.

[0036] Next, the configuration of the magnets in the rotor 60 will be described in detail. Fig. 3 is a diagram showing the configuration of the rotor 60. Fig. 3(A) is a perspective view, Fig. 3(B) is a front view, Fig. 3(C) is a plan view, and Fig. 3(D) is a cross-sectional view taken along the line BB in Fig. 3(C). In the diagram, "N" indicates the north pole and "S" indicates the south pole. For ease of explanation, the rotating shaft 62 (see Fig. 1) is omitted in the diagram.

[0037] The rotor 60 has a rotor magnet 104 along the outer circumferential surface of the rotor core 102, and a sensor magnet 106 at the axial end of the rotor core 102 (FIGS. 3(A) and 3(D)). The rotor magnet 104 is cylindrical, and its outer circumferential surface is magnetized with 10 poles (FIGS. 3(B) and 3(C)). On the other hand, the sensor magnet 106 is annular, and its plane is magnetized with 2 poles.

[0038] 3(D), the inner circumferential surface of rotor magnet 104 fits into annular groove 140, and the bottom surface of sensor magnet 106 fits into annular groove 144. That is, annular groove 140 functions as a fall-off prevention structure that prevents rotor magnet 104 from falling off from rotor core 102. Similarly, annular groove 144 functions as a fall-off prevention structure that prevents sensor magnet 106 from falling off from rotor core 102.

[0039] Given the above configuration, next, a description will be given of a method in which the magnetic sensor 119 detects the rotation angle of the rotor 60. In the following, the up-down direction in Fig. 1 will be referred to as the "opening / closing direction" or the "up-down direction".

[0040] FIG. 4 is a schematic diagram showing the relationship between the magnetic sensor 119, the sensor magnet 106, and the magnetic lines of force generated from the sensor magnet 106. As shown in FIG. FIG. 4 is a schematic diagram of the magnetic sensor 119 and the sensor magnet 106 as viewed from the side. As shown in FIG. 4, magnetic lines of force are generated from N to S of the sensor magnet 106 (permanent magnet). The magnetic sensor 119 located directly above the sensor magnet 106 is a rotary sensor of a known configuration that detects the magnetic lines of force generated from the sensor magnet 106. The magnetic sensor 119 detects the rotation angle of the sensor magnet 106 (rotor 60) based on the direction of the magnetic lines of force (described in detail later). Note that in this embodiment, the magnetic sensor 119 can detect the rotation angle of the sensor magnet 106, but the magnetic sensor 119 cannot directly detect the distance to the sensor magnet 106, in other words, the amount of movement of the operating rod 32 in the opening and closing direction.

[0041] FIG. 5 is a plan view of the sensor magnet 106. A rotational driving force is applied to the rotor 60 by passing a driving current through the coil 73 of the stator 64 in a manner described below. When the rotor 60 is rotated in the valve closing direction (downward) (hereinafter referred to as "downward rotation"), the actuation rod 32 (valve element 34) moves in the valve closing direction, i.e., downward in Fig. 1 in conjunction with the rotor 60. When the rotor 60 is rotated in the valve opening direction (hereinafter referred to as "upward rotation"), the actuation rod 32 (valve element 34) moves in the valve opening direction, i.e., upward in Fig. 1 in conjunction with the rotor 60.

[0042] The sensor magnet 106 also rotates in conjunction with the rotation of the rotor 60. As the sensor magnet 106 rotates, the magnetic field direction MA of the sensor magnet 106 also changes. When an XY coordinate system (corresponding to the horizontal plane in FIG. 1) is set as shown in FIG. 5, the angle that the magnetic field direction MA makes with the X-axis is defined as θ. The magnetic sensor 119 detects the rotation angle θ of the sensor magnet 106 using a known method shown in the angle sensor of Patent Document 1.

[0043] FIG. 6 is a graph showing the relationship between the sensor value of the sensor magnet 106 and the sensing angle. The horizontal axis indicates the rotation angle θ of the sensor magnet 106 that is the measurement target of the magnetic sensor 119 (hereinafter, sometimes referred to as the “sensing angle”). The vertical axis indicates the sensor value of the magnetic sensor 119. In this example, the sensor value is an arctangent value. As shown in FIG. 6, the magnetic sensor 119 detects a sensor value that shows a sawtooth waveform corresponding to the sensing angle. The magnetic sensor 119 converts the sensor value, which is an analog signal, into a pulse duty ratio by PWM (Pulse Width Modulation) and outputs a current that shows the modulated digital signal. At this time, the sensor value is normalized to “lower limit value DA to upper limit value TA” to determine the duty ratio of the pulse. The lower limit value DA and the upper limit value TA can be set arbitrarily. The lower limit value DA may be 0. Hereinafter, the duty ratio of the pulse may be referred to as the “angle value”. The control circuit can identify the actual rotor angle (sensing angle) based on the duty ratio (angle value) read from the pulse of the digital signal in accordance with the specifications of the magnetic sensor 119.

[0044] FIG. 7 is a graph showing the relationship between the angle value (duty ratio) and the step. In this embodiment, when the valve body 34 is moved from the highest point to the lowest point, the rotor 60 rotates a total of four times. Although details will be described later, the control circuit changes the driving current supplied to the three-phase coils 73 to change the magnetic field direction of each coil 73, thereby rotating the rotor 60. In this embodiment, the control circuit rotates the rotor 60 in units of u1 degrees (details will be described later). Hereinafter, this unit rotation amount will be referred to as a "step." Since 360 ​​degrees x 4 rotations ÷ u1 degrees = 1440 / u1 = SM4, the control circuit instructs the rotor 60 to rotate a total of SM4 steps within the operating range of the actuation rod 32. Corresponding to the four rotations of the rotor 60, the angle value changes four times between DA and TA.

[0045] Step 0 corresponds to the origin, and step n represents the nth step counted from the origin. In the figure, SM1 represents the order of steps when the mechanical angle makes one revolution, SM2 represents the order of steps when the mechanical angle makes two revolutions, SM3 represents the order of steps when the mechanical angle makes three revolutions, and SM4 represents the order of steps when the mechanical angle makes four revolutions. The mechanical angle refers to the angle in real space of a rotating body such as rotor 60.

[0046] The control circuit applies a predetermined level of drive current to the U-phase coil 73a. At this time, a similar predetermined level of drive current is applied to the V-phase coil 73b and the W-phase coil 73c. ​​By applying drive current to each coil 73, the magnetic field in the coil 73 is changed, causing the rotor 60 to rotate. A combination of the current values ​​of the drive current applied to each of the U-phase coil 73a, the V-phase coil 73b, and the W-phase coil 73c is called an "excitation pattern." In this embodiment, there are N types of excitation patterns. Changing a certain excitation pattern P1 to the adjacent excitation pattern P2 corresponds to "one step" of rotation, in other words, a rotation instruction for a unit amount of rotation.

[0047] By changing the excitation pattern, in other words by changing the excitation pattern step by step, the command angle α (ideal rotor angle) is controlled. In synchronization with the change in command angle α, the rotor 60 rotates and the sensed angle θ also changes. After changing the excitation pattern, the control circuit calculates the sensed angle θ from the angle value detected by the magnetic sensor 119, and determines whether the sensed angle θ (actual rotor angle) is following the command angle α. The state in which the sensed angle θ is following the command angle α is called "synchronization," and the state in which the sensed angle θ cannot follow the command angle α is called "loss of synchronization."

[0048] A pattern ID is assigned to each of the N types of excitation patterns. In the excitation pattern with pattern ID=N1 (hereinafter, referred to as "excitation pattern (N1)"), the drive current values ​​of the U-phase coil 73a, the V-phase coil 73b, and the W-phase coil 73c are IU(N1), IV(N1), and IW(N1), respectively. In other words, the excitation pattern (N1) means a combination of [IU(N1), IV(N1), IW(N1)]. A magnetic field is generated in each coil 73 by the drive currents IU(N1), IV(N1), and IW(N1), and the rotor 60 is guided to the command angle α according to the excitation pattern (N1).

[0049] The N types of pattern IDs correspond to N steps of one revolution of the electrical angle. The electrical angle is a theoretical value in which the N pattern IDs are evenly allocated in the range of 0 to 360 degrees. Each step n from the origin to the top is cyclically associated with a pattern ID in sequence. In addition, successive pattern IDs correspond to excitation patterns that change continuously.

[0050] When the control circuit moves from step n to step n+1, it switches from excitation pattern (N1) to excitation pattern (N1+1). This changes the magnetic field generated by each coil 73 with the drive current value [IU(N1+1), IV(N1+1), IW(N1+1)], and rotates the rotor 60 upward by a unit rotation amount. Conversely, when the control circuit moves from step n to step n-1, it switches from excitation pattern (N1) to excitation pattern (N1-1). This changes the magnetic field generated by each coil 73 with the drive current value [IU(N1-1), IV(N1-1), IW(N1-1)], and rotates the rotor 60 downward by a unit rotation amount.

[0051] In the case of the rotor 60 having the structure shown in FIG. 3, the rotor magnet 104 has five pairs of N and S poles, so that the electrical angle goes through five revolutions in one revolution (360 degrees of mechanical angle) of the rotor 60. That is, one revolution of the electrical angle corresponds to 72 degrees of mechanical angle. Also, one revolution of the electrical angle includes N steps, so the mechanical angle rotated by one step change is u1=72 / N degrees. Also, as described in relation to FIG. 7, when the rotor 60 goes through four revolutions while moving the valve disc 34 from the highest point to the origin, the movement over the entire range advances 4×5×N steps. That is, the SM4 shown in FIG. 7 is 4×5×N. Similarly, the SM1 is 5×N, the SM2 is 2×5×N, and the SM3 is 3×5×N.

[0052] In this embodiment, the position of the rotor 60 when the stopper 90 abuts against the guide member 36 (more precisely, the protrusion of the guide member 36) is set as the origin (reference position), and the control circuit records the angle value and excitation pattern at this time as "origin information (reference information)." When the motor-operated valve 1 is manufactured, origin information (reference information) specific to the motor-operated valve 1 is recorded in the non-volatile memory of the circuit board 118. Then, the control circuit adjusts the amount of movement of the operating rod 32, i.e., the valve opening degree of the motor-operated valve 1, by step n based on the origin (valve closed position).

[0053] FIG. 8 is a schematic diagram of the range of movement of the rotor 60. As shown in FIG. The right direction in FIG. 8 indicates the opening direction (upward direction) of the rotor 60, and the left direction indicates the closing direction (downward direction). The origin of step 0 is the limit position where the stopper 90 is restricted from rotating and the rotor 60 cannot rotate further downward. Step M is the valve opening point where the valve body 34 starts to rise. The value of M may be a predetermined common value or a unique value different for each motor-operated valve 1. When a unique value is used, the value of M indicating the step of the valve opening point is stored in the non-volatile memory of the circuit board 118. In the range from the origin to the valve opening point, the valve body 34 is pressed against the valve seat 24 by the elastic reaction force of the spring 116, so that the valve closed state is maintained. When the rotor 60 continues to rotate upward from the origin 0 and passes the valve opening point M, the valve body 34 leaves the valve seat 24 and the valve is in an open state. If the rotor 60 continues to rotate upward after passing the valve opening point, the valve opening degree gradually increases and the flow rate from the inlet port 26 to the outlet port 28 increases.

[0054] FIG. 9 is a transition diagram of the excitation pattern. An excitation pattern is associated with each step. The excitation pattern determines the drive current of the U phase, the drive current of the V phase, and the drive current of the W phase. The ratio of the drive current applied to each phase varies depending on the excitation pattern. The motor-operated valve control device applies the drive current of each phase while changing the excitation pattern for each step. In this embodiment, a drive current of a higher level than during rotation may be used for each phase while maintaining the ratio of the drive current of each phase specified according to the excitation pattern.

[0055] FIG. 10A is a diagram showing the relationship between the step and the ideal rotor angle. It shows the ideal rotor angle during the transition from start step n (S) to end step n (E). The ideal rotor angle means the angle of the rotor 60 at which the forces generated by the excitation pattern corresponding to the step are balanced and stable. In other words, the ideal rotor angle is a theoretical value calculated assuming that there is no load due to sliding inside the mechanism. With each step, the ideal rotor angle changes at a constant interval.

[0056] FIG. 10B is a diagram showing the relationship between steps and actual rotor angles according to the conventional technology. Here, it is assumed that a low level drive current determined by the excitation pattern is used. The rotor 60 does not rotate from the start step n(S) until the third step. In the fourth step, the rotor 60 starts rotating. In other words, the number of step delays is 3. In this way, the rotor 60 moves with a delay relative to the electric signal due to the influence of the sliding load inside the mechanism. During the rotation of the rotor 60, the actual rotor angle does not catch up with the ideal rotor angle. The number of step delays during rotation is also 3. Even when the end step n(E) is reached, there is a difference between the actual rotor angle and the ideal rotor angle. The number of step delays at the time of stopping is also 3. In other words, the stopping posture of the rotor 60 is not as intended. As a result, the gap between the valve body and the valve seat is different from the expected one, and the expected flow characteristics are not obtained. If the delay in the actual rotor angle becomes even larger, there is a risk that the stepping motor will step out.

[0057] Although it is possible to approach the ideal rotor angle by increasing the drive current, in the case of a system with limited power consumption (for example, an air conditioning system for an electric vehicle), the drive current must be kept small, and this problem arises. In this embodiment, a technique is proposed for controlling the rotor 60 to stop in an accurate attitude while saving power consumption.

[0058] FIG. 10C is a diagram showing the relationship between the step and the actual rotor angle according to the embodiment. When the stepping motor starts moving, a low level of drive current determined by the excitation pattern is used. Therefore, as in FIG. 10(B), the actual rotor angle lags behind the ideal rotor angle. In the final step n(E) where the rotor 60 is stopped, a high level of drive current is used. If a high current is passed through the three phases, a large magnetic force is generated within the stepping motor, and the force that attracts the rotor 60 to the ideal position becomes large. As a result, it becomes possible to stop the rotor 60 at the ideal angle.

[0059] According to the control method of the embodiment, the power consumption increases only for a short time just before the rotor 60 is stopped. Therefore, the overall power consumption is significantly reduced compared to a control method that constantly uses a large drive current. Increasing the torque of the stepping motor by increasing the drive current level for only a short time like this is called "micro torque up."

[0060] An upper limit is set for the drive current. Micro torque-up is performed at a current value smaller than the "magnetic saturation" current value, at which the magnetic force flowing through the stator surrounding the coil becomes saturated. In a magnetic saturation state, increasing the current does not increase the magnetic force any further, resulting in a waste of power. Keeping the drive current within a range that does not cause magnetic saturation can help reduce power consumption.

[0061] FIG. 11 is a diagram showing changes in the drive current value and the rotor angle. The standby process is the process when the rotor 60 is stopped. In the standby process, the drive current (called the "standby current") applied to the stepping motor is made extremely small. In the figure, the level of the standby current is indicated by C (W). Since only a very small magnetic force is generated within the stepping motor, the force applied to the rotor 60 is slight.

[0062] At the stage where the motor-operated valve control device receives a movement command from an external device and attempts to rotate the rotor 60, the motor-operated valve control device performs a start-up process. In the start-up process, the motor-operated valve control device magnetically grips the rotor 60 with the stator, and settles the rotor 60 in an electrically controllable position. To achieve this, the motor-operated valve control device maintains the application of the drive current of the excitation pattern corresponding to the start step n(S) for a predetermined first time. The predetermined first time is, for example, within a range of 10 to 30 msec. This allows the orientation of the rotor 60 to be aligned so as to match the ideal rotor angle of the start step n(S). In this figure, the level (low level) of the drive current of the excitation pattern is represented as C(L), and the actual rotor angle at the start is represented as A(S). The level of the drive current indicates the magnitude of the drive current. A high level of the drive current means that the drive current is doubled in proportion to the excitation pattern, and a low level of the drive current means that the drive current is reduced in proportion to the excitation pattern. As a specific index of the level of the drive current, a predetermined magnification factor by which the excitation pattern is multiplied may be considered to correspond to the level of the drive current.

[0063] Once the start-up process is complete, the process moves to during rotation. In the during rotation process, the steps are switched at regular intervals according to the rotation speed of the rotor 60. The stepping motor is then driven by the drive current (drive current at low level C(L)) of the excitation pattern corresponding to each step. As the excitation pattern changes sequentially, the rotor 60 rotates. The steps of the during rotation process are denoted by n(i), where i is a consecutive natural number.

[0064] Steps n(i) are switched in sequence in the rotation processing, and the process moves to the stop processing at the stage of switching to the end step n(E). In the stop processing, micro torque up is performed in the end step n(E). The value of the drive current of each phase is doubled while maintaining the ratio of the magnitude of the drive current of the U phase, V phase, and W phase in the excitation pattern corresponding to the end step n(E). The value of the drive current of the U phase determined in the excitation pattern is multiplied by a predetermined factor (greater than 1) to obtain the drive current value of the U phase at the high level C(H). Similarly, the value of the drive current of the V phase is multiplied by the same predetermined factor to obtain the drive current value of the V phase at the high level C(H), and the value of the drive current of the W phase is also multiplied by the same predetermined factor to obtain the drive current value of the W phase at the high level C(H). The doubled drive current of the high level C(H) of each phase is then applied to the coil of each phase. This strongly draws the rotor 60 to the ideal posture. The ideal rotor angle does not change depending on whether the level is high or low. The predetermined magnification, which is the ratio of the drive current of the high level C(H) to the drive current of the low level C(L), is within a range of, for example, 1.5 to 4.0. However, as described above, it is desirable that the drive current of the high level C(H) does not cause magnetic saturation. The micro torque-up is continued for a predetermined second time. The predetermined second time is within a range of, for example, 5 to 15 msec.

[0065] When a predetermined second time has elapsed since the start of the micro torque-up, the rotor 60 settles down to a certain degree. After that, the application of a low level drive current is switched to the excitation pattern corresponding to the end step n(E). The rotor 60 stops completely while the low level drive current is being applied. During this time, the rotor 60 rotates only slightly, and the rotor 60 stops at approximately the ideal angle. The application of the low level drive current is continued for a predetermined third time. The predetermined third time is, for example, within a range of 5 to 15 msec. While waiting for the rotor 60 to stop completely, a large force is not required, so a low level drive current is sufficient. Switching to a low level helps reduce power consumption.

[0066] At the end of the stop processing, a process for detecting out-of-step is also performed. If the actual rotor angle measured by the magnetic sensor 119 is significantly different from the ideal rotor angle targeted by the excitation pattern R(E) corresponding to the end step n(E), it is determined that out-of-step has occurred. If the deviation in the rotor angle is small, the rotor is normally synchronized and operation continues as is.

[0067] Although an example has been shown here in which the level of the drive current applied after the micro torque-up is the same as that during rotation, it may be higher or lower than that during rotation. At the very least, the level of the drive current applied after the micro torque-up is lower than the level during the micro torque-up and higher than the level of the standby current.

[0068] After the application of the drive current at a low level continues for a predetermined third time period and the step-out detection is completed, the process moves to standby processing. In standby processing, as described above, a very small standby current is applied to the stepping motor. In other words, while the rotor 60 is stopped, almost no power is consumed.

[0069] FIG. 12 is a functional block diagram of the motor-operated valve control device 200. Each component of the motor-operated valve control device 200 is realized by hardware (control circuits) including a control circuit (microcomputer) on a circuit board 118, storage devices such as memory and storage, and wired or wireless communication lines connecting them, and software stored in the storage devices and supplying processing instructions to the arithmetic unit. The computer program may be composed of device drivers and application programs, as well as libraries that provide common functions to these programs. Each block described below represents a functional block rather than a hardware-based configuration.

[0070] The motor-operated valve control device 200 includes a data processing unit 202 , a communication unit 204 , a reference information storage unit 206 , and a rotor interface unit 208 . The communication unit 204 functions as an interface with an external device via the connection terminal 81. The rotor interface unit 208 functions as an interface with the magnetic sensor 119 and the coil unit 75. The reference information storage unit 206 stores origin information (reference information). The reference information storage unit 206 is a storage area configured in a non-volatile memory. The data processing unit 202 executes various processes based on the reference information and various data acquired from the communication unit 204 and the rotor interface unit 208. The data processing unit 202 also functions as an interface with the communication unit 204, the rotor interface unit 208, and the reference information storage unit 206.

[0071] The communication unit 204 includes a receiving unit 210 that receives data and commands from an external device, and a transmitting unit 212 that transmits data to the external device.

[0072] The rotor interface unit 208 includes a rotation instruction unit 214 and a rotation detection unit 216. The rotation instruction unit 214 outputs drive currents to the U-phase coil 73a, the V-phase coil 73b, and the W-phase coil 73c. ​​The rotation detection unit 216 reads a duty ratio (angle value) from the pulse of the current received from the magnetic sensor 119.

[0073] The data processing unit 202 includes a rotation control unit 218 and a step-out detection unit 220. The rotation control unit 218 controls the rotation instruction unit 214 based on the origin information and a command received from an external device. The step-out detection unit 220 performs a process of step-out detection.

[0074] FIG. 13 is a flowchart showing the process of the motor-operated valve control device 200. When the receiver 210 receives a movement command (including the final step n(E)) from an external device (S10), the rotation controller 218 determines the rotation direction and rotation speed according to the movement command. The final step n(E) is a step for stopping the rotor, so it may be considered as a stopping step, a target step, or a destination step.

[0075] The rotation control unit 218 specifies a start step n(S) (S12). The start step n(S) is, for example, the final step n(E) in the previous movement command. The rotation control unit 218 specifies an excitation pattern R(S) corresponding to the start step n(S) according to the correspondence between the step n and the excitation pattern (S14). The rotation control unit 218 transmits the value of the drive current of each phase determined by the excitation pattern R(S) to the rotation instruction unit 214, and the rotation instruction unit 214 applies the drive current to the coil of each phase. The drive current at this time is at a low level C(L) like the drive current applied during rotation (S16). This state is maintained until a predetermined first time has elapsed. The process of S10 to S16 shown here corresponds to the start-up process (see FIG. 11).

[0076] When a predetermined first time has elapsed, the rotation control unit 218 waits for the timing to proceed to the next step n(i) according to a predetermined rotation speed (S18). When the timing to proceed to the next step n(i) arrives, the rotation control unit 218 specifies the next step n(i) toward the end step n(E) (S20). The rotation control unit 218 specifies the excitation pattern R(i) corresponding to the next step n(i) according to the correspondence between the step n and the excitation pattern (S22). The rotation control unit 218 determines whether the next step n(i) is the end step n(E) (S24). When it is determined that the next step n(i) is not the end step n(E), the rotation control unit 218 transmits the value of the drive current of each phase determined by the excitation pattern R(i) to the rotation instruction unit 214, and the rotation instruction unit 214 applies the drive current to the coil of each phase. The drive current at this time is a low level C(L). Then, the process returns to S18 and the above-mentioned process is repeated.

[0077] On the other hand, when it is determined that the next step n(i) is the end step n(E), the rotation control unit 218 multiplies the value of the drive current of each phase determined in the excitation pattern R(E) corresponding to the end step n(E) by a predetermined magnification (greater than 1) to obtain a drive current value of a high level C(H) to be applied before stopping. Then, the rotation control unit 218 transmits the drive current value of the high level C(H) for each phase to the rotation instruction unit 214, and the rotation instruction unit 214 applies the drive current of the high level C(H) to the coil of each phase in response to this. That is, the drive current of each phase is switched from the low level C(L) to the high level C(H) (S26). Since the low level drive current value is multiplied by a common predetermined magnification, the high level C(H) maintains the same ratio as the ratio of the drive current of each phase at the low level.

[0078] The applied state of the high level C(H) is maintained for a predetermined second time. When the predetermined second time has elapsed since switching to the high level C(H), the rotation control unit 218 transmits the values ​​of the drive currents of each phase determined by the excitation pattern R(E) corresponding to the end step n(E) to the rotation instruction unit 214, and the rotation instruction unit 214 applies these drive currents to the coils of each phase. As a result, the drive current of each phase is switched from the high level C(H) to the low level C(L) while maintaining the ratio of the drive currents in each phase (S28). The applied state of the low level C(L) is maintained for a predetermined third time.

[0079] When a predetermined third time has elapsed since the level was switched to the low level C(L), the out-of-step detection unit 220 performs the out-of-step detection process (S30). In the out-of-step detection process, if the actual rotor angle measured by the magnetic sensor 119 is significantly different from the ideal rotor angle targeted by the excitation pattern R(E) of the end step n(E), it is determined that out-of-step has occurred. The criterion for determining out-of-step may be defined by the deviation of the rotor angle or the difference in the number of steps. The difference in the number of steps is uniquely determined based on the deviation of the rotor angle. If out-of-step has occurred, an out-of-step error is notified to an external device. If out-of-step has not occurred, the rotation control unit 218 transmits the standby current value for each phase to the rotation instruction unit 214, and the rotation instruction unit 214 applies the standby current to the coil of each phase (S32). This causes the process to proceed to standby process (see FIG. 11). The processes of S26 to S32 described above correspond to the stop process (see FIG. 11).

[0080] [Variations] 14(A) and 14(B) are diagrams showing the relationship between steps and rotor angles in the modified example. 14(A), micro torque-up may be started from step n(E-1), which is one step before the end step n(E). Alternatively, micro torque-up may be started from step n(i), which is several steps before the end step n(E). In this way, if micro torque-up is started just before the end step and performed until the end step n(E), the period during which the rotor 60 is strongly pulled toward the ideal posture is lengthened, so that the actual rotor angle can be more reliably brought closer to the ideal rotor angle.

[0081] As shown in Fig. 14(B), micro torque-up may be performed in step n(E-1) one step before the end step n(E), and micro torque-up may not be performed in the end step n(E). Alternatively, micro torque-up may be started in step n(i) several steps before the end step n(E), and micro torque-up may be ended before the end step n(E). If the actual rotor angle is brought close to the ideal rotor angle before the end step n(E), it is possible to stop the rotor 60 in a posture close to the ideal rotor angle, even if micro torque-up is not performed in the end step n(E).

[0082] In this way, by performing micro torque-up within a range close to the end step n(E), the rotor 60 can be stopped in a position close to the ideal rotor angle. By performing micro torque-up just before the end step n(E) for a number of steps smaller than the number of step delays during rotation described in FIG. 10(B) (3 in the example of FIG. 10(B)), the actual rotor angle at the time of stopping can be brought closer to the ideal rotor angle to some extent. For example, by performing micro torque-up in step n(E-2), which is two steps before the end step n(E), the rotor angle can be adjusted to the ideal rotor angle in step n(E-2), so that the actual rotor angle is closer to the ideal rotor angle than the actual rotor angle in the end step n(E) when micro torque-up is not performed as shown in FIG. 10(B).

[0083] Also, if it is sufficient to suppress the step deviation to such an extent that it is not judged as out of synchronism, it is sufficient to perform micro torque-up a number of times before the end step n(E) that is smaller than the difference in the number of steps at which it is judged as out of synchronism. For example, if micro torque-up is performed in step n(E-3), which is three steps before the end step n(E), it will be possible to match the ideal rotor angle in step n(E-3), so the number of steps delayed when the rotor stops will be three or less. If the specifications for judging out of synchronism are such that it is judged as out of synchronism when the difference in the number of steps corresponding to the deviation between the actual rotor angle when the rotor 60 stops and the ideal rotor angle in the end step n(E) is four or more, it will not be judged as out of synchronism.

[0084] In this way, by performing micro torque-up at least once in any step within a specified range from the step before the end step n(E) to the end step n(E), the effect of reducing power consumption and increasing the accuracy of rotor stopping is achieved.

[0085] In the above embodiment, a configuration in which the magnetic sensor 119 faces the sensor magnet 106 in the axial direction is exemplified (see FIG. 1). In a modified example, the magnetic sensor may be disposed to the side (radially outward) of the sensor magnet. That is, the two may face each other in the radial direction. The outer peripheral surface of the sensor magnet may be magnetized. The number of poles may be appropriately set, for example, to two poles on the valve body.

[0086] In the above embodiment, a configuration in which the rotor magnet 104 and the sensor magnet 106 are spaced apart in the axial direction has been exemplified. In a modified example, the rotor magnet and the sensor magnet may be integrally configured. The rotor magnet portion and the sensor magnet portion may be integrally molded in the magnet portion molding process. In that case, the area (outer diameter) of the sensor magnet may be increased so that the magnetic sensor can reliably detect magnetic flux. Since the sensor magnet protrudes beyond the outer periphery of the rotor core, it becomes easier to injection mold the sensor magnet and the rotor magnet.

[0087] In each embodiment, a laminated core (laminated magnetic core) is exemplified as the core of the stator. In a modified example, a dust core or other core may be adopted. A dust core is also called a "powder core" and is obtained by powdering a soft magnetic material, coating the powder with a non-conductive resin or the like, kneading the powder with a resin binder, and compression molding and heating it.

[0088] In each embodiment, a configuration in which the drive circuit, control circuit, communication circuit, and power supply circuit are mounted on the underside of the circuit board has been illustrated, but the circuits to be mounted can be changed as appropriate. For example, the drive circuit and power supply circuit may be mounted, while the control circuit may be installed outside the motor-operated valve. In addition, each circuit may be mounted on the upper surface of the circuit board.

[0089] In each embodiment, a PM type stepping motor is used as the motor unit, but a hybrid type stepping motor may also be used. In the above embodiments, the motor unit is a three-phase motor, but it may be another type of motor such as a two-phase, four-phase, or five-phase motor. The number of electromagnetic coils in the stator is not limited to three or six, and may be set appropriately according to the number of phases of the motor.

[0090] The motor-operated valve of each embodiment is preferably applied to a refrigeration cycle that uses a refrigerant such as an alternative fluorocarbon (HFC-134a) as a refrigerant, but can also be applied to a refrigeration cycle that uses a refrigerant with a high operating pressure such as carbon dioxide. In that case, an external heat exchanger such as a gas cooler is disposed in the refrigeration cycle instead of a condenser.

[0091] In each embodiment, the motor-operated valve is configured as an expansion valve, but it may be configured as an opening / closing valve or a flow control valve that does not have an expansion function.

[0092] In each embodiment, the motor-operated valve is applied to the refrigeration cycle of an automotive air conditioner, but the motor-operated valve can be applied to any air conditioner equipped with an electric expansion valve, not limited to vehicles. Also, the motor-operated valve can be configured to control the flow of a fluid other than a refrigerant.

[0093] The present embodiment is not limited to electric vehicles, but can be applied to various types of vehicles.

[0094] The sensor magnet 106 may be magnetized with four poles on both sides (one-sided valve body with two poles magnetized on both sides). The magnetic flux can be strengthened by reversing the polarity of the magnetic poles on the upper and lower sides. In this case, even if the rotor 60 is displaced in the valve closing direction and the distance between the sensor magnet 106 and the magnetic sensor 119 increases, the sensitivity of the magnetic sensor 119 can be maintained at a good level. [Explanation of symbols]

[0095] 1 motor-operated valve, 2 valve body, 3 motor unit, 5 body, 6 first body, 8 second body, 10 male thread, 12 seal housing, 14 seal ring, 16 concave fitting portion, 18 seal housing, 20 seal ring, 22 valve hole, 24 valve seat, 26 inlet port, 28 outlet port, 30 valve chamber, 32 operating rod, 34 valve body, 36 guide member, 38 male thread, 40 large diameter portion, 42 spring retainer, 44 spring retainer, 46 spring, 52 locking portion, 60 rotor, 62 rotating shaft, 64 stator, 66 can, 70 laminated core, 73 coil, 73a U-phase coil, 73b V-phase coil, 73c W-phase coil, 74 bobbin, 75 coil unit, 76 case, 77 cover, 78 stator unit, 79 Connector section, 80 seal housing section, 81 connection terminal, 82 seal ring, 90 stopper, 102 rotor core, 104 rotor magnet, 106 sensor magnet, 108 female screw, 109 screw feed mechanism, 110 reduced diameter section, 112 bottom section, 114 stopper, 116 spring, 117 terminal, 118 circuit board, 119 magnetic sensor, 120 slot, 122 salient pole, 124 slit, 140 annular groove, 144 annular groove, 200 motor-operated valve control device, 202 data processing section, 204 communication section, 206 reference information storage section, 208 rotor interface section, 210 receiving section, 212 transmitting section, 214 rotation instruction section, 216 rotation detection section, 218 rotation control section, 220 step-out detection section

Claims

1. 1. An electric valve control device for controlling an electric valve having a stepping motor that rotates a rotor by a drive current applied to each phase based on an excitation pattern corresponding to a step, and a mechanism that converts the rotational motion of the rotor into axial motion of a valve body, a rotation control unit that sequentially switches the steps when rotating the rotor, and determines the drive current for each phase in accordance with the excitation pattern associated with the step for each switched step; a rotation instruction unit that applies the drive current of each phase specified by the rotation control unit to the stepping motor, the rotation control unit, in a previous step close to an end step of the steps which are sequentially switched during rotation of the rotor, maintains the ratio of the drive currents of the respective phases specified according to the excitation pattern corresponding to the previous step, and in the end step, specifies a drive current for each phase that is at a level higher than that during the rotation while maintaining the ratio of the drive currents of the respective phases specified according to the excitation pattern corresponding to the end step; The motor-operated valve control device is characterized in that, in the previous step, the rotation instruction unit applies the drive current of each phase, the ratio of which is maintained by the rotation control unit, to the stepping motor, and, in the termination step, applies the high level drive current of each phase specified by the rotation control unit to the stepping motor.

2. An electric valve control device as described in claim 1, characterized in that the high level of drive current is smaller than the current value that causes magnetic saturation.

3. 2. The motor-operated valve control device according to claim 1, wherein a step difference between the preceding step and the end step is smaller than a step difference at which it is determined that the stepping motor has lost synchronism.

4. 2. The motor-operated valve control device according to claim 1, wherein a step difference between the preceding step and the end step is smaller than a delay number of steps during the rotation.

5. before placing the stepping motor in a standby state in the termination step, the rotation control unit specifies a drive current for each phase that is lower than the high level drive current; 2. The motor-operated valve control device according to claim 1, wherein the rotation instruction unit switches the high level drive current applied to each of the phases to the low level drive current in the ending step.

6. a computer that controls an electrically-operated valve having a stepping motor that rotates a rotor by a drive current applied to each phase based on an excitation pattern corresponding to a step, and a mechanism that converts the rotational motion of the rotor into axial motion of a valve body; a rotation control function of sequentially switching the steps when rotating the rotor and specifying the drive current for each phase in accordance with the excitation pattern associated with the step for each switched step; a rotation instruction function of applying the drive current of each phase specified by the rotation control function to the stepping motor; In the rotation control function, in a previous step close to an end step of the steps which are sequentially switched during rotation of the rotor, a ratio of the drive current of each of the phases specified according to the excitation pattern corresponding to the previous step is maintained, and in the end step, a drive current of a level higher than that during the rotation is specified for each of the phases while maintaining the ratio of the drive current of each of the phases specified according to the excitation pattern corresponding to the end step; an electric valve control program, characterized in that in the rotation instruction function, in the previous step, the drive current of each phase, the ratio of which is maintained by the rotation control function, is applied to the stepping motor, and in the termination step, the drive current of the high level of each phase specified by the rotation control function is applied to the stepping motor.

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