JP2023025319A - Motor valve control device and motor valve control program - Google Patents

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

An automobile air conditioner is generally configured by arranging a compressor, a condenser, an expansion device, an evaporator, etc. in a refrigeration cycle. A refrigerating cycle is provided with various control valves, such as an expansion valve as an expansion device, for controlling the flow of refrigerant. 2. Description of the Related Art With the recent spread of electric vehicles and the like, electric valves equipped with stepping motors as drive units are being widely used.

As such an electric valve, there is known one that includes a magnetic sensor for detecting the degree of opening of the valve (see Patent Document 1, for example). A valve body is provided at one end of an operating 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. Rotational motion of the rotor is converted into axial motion of the valve body by the screw feed mechanism. By capturing the change in magnetic flux accompanying the rotation of the rotor with a magnetic sensor, the rotation angle of the sensor magnet and thus the axial position of the valve body can be detected, and the valve opening can be calculated.

A reference position, which serves as a control reference, is set for the valve body that moves up and down in the electric valve. When the rotor continues to rotate in the valve closing direction and reaches a reference position also called an "origin", the rotation of the rotor is restricted by a stopper (see Patent Document 2, for example).

Japanese Patent Application Laid-Open No. 2018-135908 JP 2020-204344 A

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

As a method for preventing the rotation of the rotor from being delayed, it is conceivable to increase the level of the drive current applied to the stepping motor. However, if a large driving current is continuously applied, there is a problem that power consumption increases.

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.

An electric valve control device according to one aspect of the present invention includes a stepping motor that rotates a rotor by driving current applied to each phase based on an excitation pattern corresponding to a step, and a rotor that changes the rotational motion of the rotor into axial motion of the valve body. A motor-operated valve control device for controlling a motor-operated valve having a mechanism that rotates a rotor, wherein steps are sequentially switched when a rotor is rotated, and for each switched step, each phase is controlled according to an excitation pattern associated with the step. A rotation control unit that specifies a drive current, and a rotation instruction unit that applies the drive current of each phase specified by the rotation control unit to the stepping motor. Then, while maintaining the ratio of the drive current of each phase specified according to the excitation pattern, a drive current of a higher level than during rotation is specified for each phase, and the rotation instruction unit controls each phase specified by the rotation control unit A high level of drive current is applied to the stepping motor.

A motor-operated valve control program according to one aspect of the present invention includes 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 changes the rotational motion of the rotor to the axial motion of the valve body. A computer that controls a motor-operated valve having a mechanism that causes the rotor to rotate, sequentially switches steps, and for each switched step, specifies the drive current of each phase according to the excitation pattern associated with the step. A rotation control function and a rotation instruction function of applying the drive current of each phase specified by the rotation control function to the stepping motor are exhibited, and in the rotation control function, before the rotating rotor stops, the excitation pattern is changed. While maintaining the ratio of the drive current of each phase specified according to, specify a drive current of a higher level than during rotation for each phase, and in the rotation instruction function, the high level of each phase specified by the rotation control function A drive current is applied to the stepping motor.

According to the present invention, the rotor of the motor-operated valve can be stopped at a more accurate angle while suppressing power consumption.

1 is a cross-sectional view showing an electrically operated valve according to an embodiment; FIG. FIG. 3 is a diagram showing the configuration of a stator and its surroundings; It is a figure showing the structure of a rotor. FIG. 2 is a schematic diagram showing the relationship between a magnetic sensor, a sensor magnet, and magnetic lines of force generated from the sensor magnet; It is a top view of a sensor magnet. 4 is a graph showing the relationship between the sensor value of the sensor magnet and the sensing angle; 4 is a graph showing the relationship between an angle value (duty ratio) and steps. FIG. 4 is a schematic diagram of the movement range of the rotor; 4 is a transition diagram of excitation patterns; FIG. FIG. 10A is a diagram showing the relationship between the step and the ideal rotor angle. FIG. 10(B) is a diagram showing the relationship between the step and the actual rotor angle according to the prior art. FIG. 10(C) is a diagram showing the relationship between the step and the actual rotor angle according to the embodiment. It is a figure which shows the change of a drive current value and a rotor angle. It is a functional block diagram of an electric valve control device. 4 is a flow chart showing the processing steps of the electric valve control device; FIG. 14A is a diagram showing the relationship between the step and the rotor angle in the modified example. FIG. 14B is a diagram showing the relationship between the step and the rotor angle in the modified example.

[Embodiment]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, for the sake of convenience, the positional relationship of each structure may be expressed based on the illustrated state. Also, in the following embodiments and modifications thereof, substantially the same constituent elements are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 1 is a cross-sectional view showing an electrically operated valve according to an embodiment.
The motor-operated valve 1 is applied to a refrigerating cycle of an automotive 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 delivers it in the form of mist, and an evaporator that evaporates the refrigerant in the form of mist. An evaporator or the like is provided to cool the air in the passenger compartment by the latent heat of evaporation. Motor operated valve 1 functions as an expansion valve for the refrigeration cycle.

A motor-operated valve 1 is configured by assembling a valve body 2 and a motor unit 3 . The valve main body 2 has a body 5 that accommodates a valve portion. The body 5 functions as a "valve body". The body 5 is configured 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 valve seat 24 is provided in the second body 8, 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 .

The first body 6 has a stepped cylindrical shape whose outer diameter gradually decreases downward. The outer diameter of the upper end portion of the first body 6 is slightly reduced, and a locking portion 52 is formed by a step. A male thread 10 is formed on the lower outer peripheral surface of the first body 6 for assembling the electric valve 1 to a piping body (not shown). A pipe extending from the condenser side, a pipe leading to the evaporator, and the like are connected to the pipe body, but the details thereof will not be described. A seal accommodating 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.

A circular hole-shaped concave fitting portion 16 is provided in the lower portion of the first body 6 . The second body 8 has a cylindrical shape with a bottom, and its upper portion is press-fitted into the concave fitting portion 16 . A seal accommodating portion 18 consisting of an annular groove is formed in the lower outer peripheral surface of the second body 8, and a seal ring 20 is fitted therein. A valve hole 22 is provided so as to axially penetrate the bottom of the second body 8 , 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 bottom. 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 communicate through the valve chamber 30 .

An operating rod 32 extending from a rotor 60 of the motor unit 3 is inserted inside the body 5 . The operating rod 32 passes through the valve chamber 30 . The operating rod 32 is obtained by cutting a bar made of non-magnetic metal, and a needle-shaped valve element 34 is integrally provided in the lower part thereof. The valve portion is opened and closed by attaching and detaching the valve element 34 to and from the valve seat 24 from the valve chest 30 side.

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

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 bearings 42 and 44 to bias the valve body 34 in the valve closing direction.

On the other hand, the motor unit 3 is configured as a three-phase stepping motor including a rotor 60 and a stator 64. As shown in FIG. The motor unit 3 has a cylindrical can 66 with a bottom, the rotor 60 is arranged inside the can 66, and the stator 64 is arranged outside. The can 66 is a bottomed cylindrical member that covers the space in which the valve body 34 and its drive mechanism are arranged and that encloses the rotor 60. The can 66 acts as an inner pressure space (internal space) where the pressure of the refrigerant acts. and an outer non-pressure space (external space).

The can 66 is made of a non-magnetic metal (SUS in this embodiment), and is coaxially attached to the upper end of the first body 6 so that its lower portion is externally inserted. The amount of insertion of the can 66 is restricted by locking the lower end of the can 66 with the locking portion 52 . The body 5 and the can 66 are fixed and sealed by all-around welding (not shown) along the boundary between the lower end of the can 66 and the first body 6 . A space surrounded by the body 5 and the can 66 forms the pressure space.

The stator 64 is configured by arranging a plurality of salient poles at regular intervals on the inner peripheral portion 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) is attached to each salient pole. These coils 73 and bobbins 74 constitute a "coil unit 75". In this embodiment, three motor units 75 for supplying three-phase current are provided at intervals of 120 degrees with respect to the central axis of the laminated core 70 (details will be described later).

The stator 64 is provided integrally with the case 76 of the motor unit 3 . That is, the case 76 is obtained by injection molding (also referred to as “insert molding” or “molding”) of a corrosion-resistant resin material. The stator 64 is covered with molding resin obtained by injection molding. The case 76 is made of the mold resin. Hereinafter, the molded product of the stator 64 and the case 76 will also be referred to as a "stator unit 78".

The stator unit 78 has a hollow structure and is attached to the body 5 while coaxially passing through the can 66 . A seal accommodating portion 80 consisting of an annular groove is formed on the outer peripheral surface slightly below the locking portion 52 of the first body 6, and a seal ring 82 (O-ring) is fitted. A 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 to prevent the outside atmosphere (such as water) from entering the gap between the can 66 and the stator 64. is prevented.

Rotor 60 includes a cylindrical rotor core 102 assembled to rotating shaft 62 , rotor magnets 104 provided on the outer peripheral surface of rotor core 102 , and sensor magnets 106 provided on the upper end surface of rotor core 102 . The rotor core 102 is attached to the rotating shaft 62 . The rotor magnet 104 is magnetized (magnetized) with a plurality of poles in its circumferential direction. The sensor magnet 106 is also magnetized (magnetized) with 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.

The rotary shaft 62 is a cylindrical shaft with a bottom, and is fitted around the guide member 36 with its open end facing downward. A female thread 108 is formed on the lower inner peripheral surface of the rotating shaft 62 and meshes with the male thread 38 of the guide member 36 . Rotational motion of the rotor 60 is converted into axial motion of the operating rod 32 by the screw feed mechanism 109 using these threaded portions. As a result, the valve body 34 is moved (lifted/lowered) in the axial direction, that is, in the opening/closing direction of the valve portion.

The diameter of the upper portion of the operating rod 32 is reduced, and the reduced diameter portion 110 penetrates the bottom portion 112 of the rotating shaft 62 . An annular stopper 114 is fixed to the distal end of the reduced diameter portion 110 . On the other hand, a spring 116 is interposed between the base end of the diameter-reduced portion 110 and the bottom portion 112 to urge the operating rod 32 downward (that is, in the valve closing direction). With such a configuration, when the valve is opened, the operating rod 32 is displaced integrally with the rotor 60 in such a manner that the stopper 114 is locked to the bottom portion 112 . On the other hand, when the valve is closed, the spring 116 is compressed by the reaction force that the valve element 34 receives from the valve seat 24 . The valve element 34 can be pressed against the valve seat 24 by the elastic reaction force of the spring 116 at this time, and the seating performance (valve closing performance) of the valve element 34 can be enhanced.

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

A magnetic sensor 119 is provided on the surface of the circuit board 118 facing the sensor magnet 106 . The magnetic sensor 119 axially faces the sensor magnet 106 through 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 (in this embodiment, the rotation angle of the rotor 60) by capturing this change in magnetic flux. Based on the displacement of the rotor 60, the control unit calculates the axial position of the valve body 34 and thus the valve opening degree.

A pair of terminals 117 connected to the coil 73 extends from each bobbin 74 and is connected to a circuit board 118 . A power supply terminal, a ground terminal, and a communication terminal (also collectively referred to as “connection terminals 81”) extend from the circuit board 118 and pass through the side wall of the case 76 to be drawn to the outside. A connector portion 79 is provided integrally with the side portion of the case 76 , and connection terminals 81 are arranged inside the connector portion 79 .

A stopper 90 is formed below the rotor 60 . As shown in Patent Document 2, the structure of the stopper 90 is known. When the operating rod 32 reaches the valve closing position, the spring 116 applies an elastic reaction force to the rotor 60 to keep the valve closed stably. Ultimately, the stopper 90 comes into contact with a projection (locking portion) (not shown) formed as a part of the guide member 36, thereby completely restricting the rotation of the rotor 60 in the valve closing direction. Hereinafter, the step when the stopper 90 comes into contact with the protrusion is referred to as the "origin" of the step. Further, in this embodiment, the valve body 34 is assumed to be at the "reference position" at the origin of the step.

FIG. 2 is a diagram showing the configuration of the stator 64 and its surroundings. FIG. 2A is a cross-sectional view of the stator unit 78 corresponding to the cross-section taken along line AA of FIG. FIG. 2B is a diagram showing only the stator 64 (state before resin molding). For reference, FIG. 2A shows the can 66 and the rotor 60 (see two-dot chain lines).

Since the motor unit 3 is a three-phase motor, the coil units 75 are provided at equal intervals around the axis L of the rotor 60 as shown in FIG. 2(A). As shown in FIG. 2B, slots 120a to 120c (collectively referred to as "slots 120" when not distinguished) are formed in the inner peripheral portion of the laminated core 70 at intervals of 120 degrees with respect to the axis L. is provided. In each slot 120, salient poles 122a to 122c (generically referred to as "salient poles 122") projecting radially inward from the center thereof are formed. (collectively referred to as "coil 73") are assembled. A slit 124 having a U-shaped cross section is also formed between the slots 120 adjacent to each other to optimize the magnetic path.

The rotor magnet 104 faces the salient poles 122a to 122c via the can 66. As shown in FIG. In this embodiment, as shown in FIG. 2(A), the rotor magnet 104 is magnetized with 10 male-threaded poles, but the number of poles can be set appropriately.

Next, the configuration of the magnets in rotor 60 will be described in detail.
FIG. 3 is a diagram showing the configuration of the rotor 60. As shown in 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 line BB of FIG. 3(C). "N" in the figure indicates an N pole, and "S" indicates an S pole. For convenience of explanation, the illustration of the rotating shaft 62 (see FIG. 1) is omitted in FIG.

The rotor 60 has a rotor magnet 104 along the outer peripheral surface of the rotor core 102 and a sensor magnet 106 at the axial end of the rotor core 102 (FIGS. 3A and 3D). The rotor magnet 104 has a cylindrical shape and is magnetized with 10 poles on its outer peripheral surface (FIGS. 3(B) and 3(C)). On the other hand, the sensor magnet 106 has an annular shape and is magnetized with planar two poles.

As shown in FIG. 3D, the inner peripheral surface of the rotor magnet 104 is fitted in the annular groove 140, and the lower surface of the sensor magnet 106 is fitted in the annular groove 144. As shown in FIG. That is, the annular groove 140 functions as a drop-off prevention structure that prevents the rotor magnet 104 from dropping off from the rotor core 102 . Similarly, annular groove 144 functions as a drop-off prevention structure that prevents drop-off of sensor magnet 106 from rotor core 102 .

Based on the above configuration, a method for detecting the rotation angle of the rotor 60 by the magnetic sensor 119 will now be described. In addition, below, the up-down direction of FIG. 1 is called "opening-and-closing direction" or "up-down direction."

FIG. 4 is a schematic diagram showing the relationship between the magnetic sensor 119, the sensor magnet 106, and the lines of magnetic 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 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). A magnetic sensor 119 positioned directly above the sensor magnet 106 is a known rotary sensor that detects 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 (details will be described later). In the present embodiment, the magnetic sensor 119 can detect the rotation angle of the sensor magnet 106. The magnetic sensor 119 directly detects the distance to the sensor magnet 106, in other words, the amount of movement of the operating rod 32 in the opening/closing direction. It is assumed that it cannot be detected.

FIG. 5 is a plan view of the sensor magnet 106. FIG.
Rotational driving force is applied to the rotor 60 by applying a driving current to the coils 73 of the stator 64 by a method described later. When the rotor 60 is rotated in the valve closing direction (downward direction) (hereinafter referred to as “downward rotation”), the operating rod 32 (valve element 34) moves in the valve closing direction, that is, in the drawing of FIG. Move down. When the rotor 60 is rotated in the valve-opening direction (hereinafter referred to as "upward rotation"), the operating rod 32 (valve body 34) moves in the valve-opening direction, that is, upward in FIG. .

As the rotor 60 rotates, the sensor magnet 106 also rotates. As the sensor magnet 106 rotates, the magnetic field direction MA of the sensor magnet 106 also changes. When the XY coordinate system (corresponding to the horizontal plane in FIG. 1) is set as shown in FIG. 5, the angle formed by the magnetic field direction MA with the X axis is assumed to be θ. The magnetic sensor 119 detects the rotation angle θ of the sensor magnet 106 by a known method shown in the angle sensor of Patent Document 1.

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 to be measured by the magnetic sensor 119 (hereinafter sometimes referred to as "sensing angle"). The vertical axis is the sensor value of the magnetic sensor 119 . The sensor values in this example are arctangent values. As shown in FIG. 6, the magnetic sensor 119 detects a sensor value showing a sawtooth waveform corresponding to the sensing angle. The magnetic sensor 119 replaces the sensor value, which is an analog signal, with a pulse duty ratio by PWM (Pulse Width Modulation), and outputs a current indicating a modulated digital signal. At this time, the duty ratio of the pulse is determined by normalizing the sensor value from "lower limit value DA to upper limit value TA". The lower limit value DA and the upper limit value TA can be set arbitrarily. The lower limit value DA may be zero. Hereinafter, the pulse duty ratio may be referred to as an "angle value". The control circuit can identify the actual rotor angle (perceived angle) based on the duty ratio (angle value) read from the pulse of the digital signal according to the specifications of the magnetic sensor 119 .

FIG. 7 is a graph showing the relationship between the angle value (duty ratio) and step.
In this embodiment, when moving the valve body 34 from the highest point to the lowest point, the rotor 60 rotates four times in total. Although details will be described later, the control circuit rotates the rotor 60 by changing the magnetic field direction of each coil 73 by changing the drive current supplied to the three-phase coils 73 . 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". From 360 degrees×4 rotations÷u1 degrees=1440/u1=SM4, the control circuit instructs the rotor 60 to rotate a total of 4 steps of SM within the operating range of the operating rod 32 . The angle value changes four times between DA and TA corresponding to four rotations of the rotor 60 .

Step 0 corresponds to the origin, and step n represents the nth step counted from the origin. SM1 shown in the figure 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, and SM3 represents the order of steps when the mechanical angle makes three revolutions. , and SM4 represents the order of steps when the mechanical angle rotates four times. A mechanical angle refers to an angle in real space of a rotating body such as the rotor 60 .

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

By changing the excitation pattern, in other words, by changing the excitation pattern step by step, the indicated angle α (ideal rotor angle) is controlled. The rotor 60 rotates in synchronization with the change in the indicated angle α, and the sensing angle θ also changes. After changing the excitation pattern, by calculating the sensing angle θ from the angle value detected by the magnetic sensor 119, the control circuit can detect a state in which the sensing angle θ (actual rotor angle) follows the indicated angle α. It is determined whether or not. The state in which the sensing angle .theta.

A pattern ID is assigned to each of the N types of excitation patterns. IU(N1), IV (N1) and IW(N1). That is, the excitation pattern (N1) means a combination of [IU(N1), IV(N1), IW(N1)]. Drive currents IU(N1), IV(N1) and IW(N1) generate a magnetic field in each coil 73 to guide the rotor 60 to an indicated angle α corresponding to the excitation pattern (N1).

The N types of pattern IDs correspond to N steps for one round of the electrical angle. The electrical angle is a theoretical value obtained by evenly assigning N pattern IDs in the range of 0 to 360 degrees. Each step n from the origin to the top is cyclically associated with the pattern ID in sequence. A continuous pattern ID corresponds to an excitation pattern that changes continuously.

When the control circuit moves from step n to step n+1, it switches from excitation pattern (N1) to excitation pattern (N1+1). As a result, the magnetic field generated by each coil 73 is changed with the drive current values [IU(N1+1), IV(N1+1), IW(N1+1)], and the rotor 60 is rotated upward by the 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). As a result, the magnetic field generated by each coil 73 is changed by the drive current values [IU(N1-1), IV(N1-1), IW(N1-1)], and the rotor 60 is rotated downward by the unit rotation amount.

In the case of the rotor 60 having the structure shown in FIG. 3, since the rotor magnet 104 has five pairs of N and S poles, the rotor 60 rotates five times in one revolution (360 mechanical degrees). That is, one round of the electrical angle corresponds to 72 degrees of the mechanical angle. Also, since one revolution of the electrical angle includes N steps, the mechanical angle rotated by one step change is u1=72/N degrees. Further, as described with reference to FIG. 7, when the rotor 60 is rotated four times while the valve body 34 is moved from the highest point to the origin, 4.times.5.times.N steps are advanced in the movement over the entire area. become. That is, SM4 shown in FIG. 7 is 4×5×N. Similarly, SM1 is 5*N, SM2 is 2*5*N, and SM3 is 3*5*N.

In this embodiment, the position of the rotor 60 when the stopper 90 contacts the guide member 36 (more precisely, the projection of the guide member 36) is defined as the origin (reference position), and the control circuit controls the angle value and The excitation pattern is recorded as "origin information (reference information)". When the motor-operated valve 1 is manufactured, origin information (reference information) unique 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, that is, the valve opening degree of the motor-operated valve 1, by step n based on the origin (valve closed position).

FIG. 8 is a schematic diagram of the movement range 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 in rotation and the rotor 60 cannot rotate further downward. Step M is the valve opening point at which the valve element 34 starts to rise. The value of M may be a predetermined common value, or may be a peculiar value different for each motor operated valve 1 . When the eigenvalue is used, the value of M indicating the valve opening step 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 the valve closed state is maintained. When the rotor 60 continues to rotate upward from the origin 0 and exceeds the valve opening point M, the valve body 34 separates from the valve seat 24 and the valve is opened. As the upward rotation of the rotor 60 continues even after the valve opening point is exceeded, the valve opening degree gradually increases, and the flow rate from the inlet port 26 to the outlet port 28 increases.

FIG. 9 is a transition diagram of excitation patterns.
Each step is associated with an excitation pattern. The excitation pattern defines a U-phase drive current, a V-phase drive current, and a W-phase drive current. The ratio of the drive current applied to each phase differs 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 higher level of drive current may be used for each phase than during rotation while maintaining the ratio of the drive current for each phase specified according to the excitation pattern.

FIG. 10A is a diagram showing the relationship between the step and the ideal rotor angle.
The ideal rotor angle is shown 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 steps 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. The ideal rotor angle changes at regular intervals each time one step advances.

FIG. 10(B) is a diagram showing the relationship between the step and the actual rotor angle according to the prior art.
Here, it is assumed that a low-level drive current determined by the excitation pattern is used. The rotor 60 does not rotate until the third step from the start step n(S). In a fourth step, rotor 60 begins to rotate. That is, the step delay number is three. Thus, the rotor 60 moves with a delay with respect to the electric signal due to the influence of the sliding load inside the mechanism. During 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 three. 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 stop is also three. In other words, the stop posture of the rotor 60 is not as intended. As a result, the gap between the valve body and the valve seat will be different than expected, and the expected flow rate characteristics will not be obtained. If the actual rotor angle lags further, there is a risk that the stepping motor will step out.

It is possible to approach the ideal rotor angle by increasing the drive current. such a problem arises. This embodiment proposes a technique for controlling the rotor 60 to stop in an accurate attitude while saving power consumption.

FIG. 10(C) is a diagram showing the relationship between the step and the actual rotor angle according to the embodiment.
A low-level drive current determined by the excitation pattern is used to start the stepping motor. Therefore, as in FIG. 10B, the actual rotor angle lags behind the ideal rotor angle. At the end step n(E), which stops the rotor 60, a high level of drive current is used. If a high current is applied to the three phases, a large magnetic force is generated within the stepping motor, and the force that attracts the rotor 60 to the ideal posture becomes large. As a result, the rotor 60 can be stopped at an ideal angle.

According to the control method of the embodiment, the power consumption increases for a short period of time immediately before the rotor 60 is stopped. Therefore, the power consumption as a whole is greatly suppressed compared to the control method that always uses a large drive current. Increasing the torque of the stepping motor by increasing the level of the drive current for a short period of time in this way is called "microtorque-up."

An upper limit is set for the drive current. Micro-torque up is performed with a value smaller than the current value at which the magnetic force flowing through the stator around the coil is saturated (magnetic saturation). This is because in the state of magnetic saturation, even if the current is increased, the magnetic force does not increase any further, which wastes power. Keeping the drive current within a range in which magnetic saturation does not occur can contribute to the suppression of power consumption.

FIG. 11 is a diagram showing changes in drive current value and rotor angle.
The standby process is a process when the rotor 60 is stopped. During the standby process, the drive current (referred to as "standby current") applied to the stepping motor is made extremely small. In the figure, the standby current level is indicated by C (W). The force exerted on the rotor 60 is negligible since very little magnetic force exists within the stepping motor.

When the movement command is received from the external device and the rotor 60 is about to rotate, the motor-operated valve control device performs start-up processing. In the start-up process, the motor-operated valve control device causes the stator to magnetically grip the rotor 60 to settle the rotor 60 into an electrically controllable posture. Therefore, the motor-operated valve control device maintains the application of the drive current in the excitation pattern corresponding to the start step n(S) for a predetermined first time. The predetermined first time is, for example, within the range of 10-30 msec. This orients the rotor 60 to match the ideal rotor angle of the starting step n(S). In this figure, the level (low level) of the drive current of the excitation pattern is denoted by C(L), and the actual rotor angle at the start is denoted by A(S). The drive current level indicates the magnitude of the drive current. If the drive current level is high, the drive current is doubled in proportion to the excitation pattern, and if the drive current level is low, the drive current is reduced in proportion to the excitation pattern. As a specific index of the level of the drive current, it may be considered that a predetermined magnification by which the excitation pattern is multiplied corresponds to the level of the drive current.

When the start-up process ends, the process moves to the during-rotation process. In the during-rotation process, steps are switched at regular intervals according to the rotation speed of the rotor 60 . Then, the stepping motor is driven by the drive current of the excitation pattern corresponding to each step (driving current of low level C(L)). The rotor 60 rotates because the excitation pattern changes sequentially. The steps of the in-rotation process are denoted by n(i). i is a continuous natural number.

Step n(i) is sequentially switched in the rotating process, and at the stage of switching to the end step n(E), the stop process is started. In the stopping process, a micro-torque-up is performed at the end step n(E). While maintaining the magnitude ratio of the U-phase, V-phase and W-phase drive currents in the excitation pattern corresponding to the end step n(E), the value of the drive current for each phase is doubled. The value of the U-phase drive current determined by the excitation pattern is multiplied by a predetermined magnification (greater than 1) to obtain the U-phase drive current value of the high level C(H). Similarly, the value of the V-phase drive current is multiplied by the same predetermined multiplier to obtain the V-phase drive current value at a high level C(H), and the W-phase drive current value is also multiplied by the same predetermined multiplier to obtain A W-phase drive current value at a high level C(H) is obtained. Then, the doubled drive current of the high level C(H) of each phase is applied to the coil of each phase. As a result, the rotor 60 is strongly drawn 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 high level C(H) drive current to the low level C(L) drive current, is, for example, within the range of 1.5 to 4.0. However, as described above, it is desirable that the high level C(H) drive current does not cause magnetic saturation. The microtorque up continues for a predetermined second time. The predetermined second time is, for example, within the range of 5-15 msec.

When a predetermined second time elapses from the start of the microtorque-up, the movement of the rotor 60 settles down to some extent. After that, the excitation pattern corresponding to the end step n(E) is switched to apply a low-level drive current. The rotor 60 comes to a complete stop while the low level drive current is being applied. Rotation of the rotor 60 during this time is slight, and the rotor 60 stops at a substantially ideal angle. Application of the low level drive current is continued for a predetermined third time. The predetermined third time is, for example, within the range of 5-15 msec. While waiting for the rotor 60 to come to a complete stop, a low level of drive current is sufficient since no large force is required. Switching to a low level helps reduce power consumption.

A step-out detection process is also performed at the end of the stop process. If the actual rotor angle measured using the magnetic sensor 119 deviates greatly from the ideal rotor angle targeted by the excitation pattern R(E) corresponding to the end step n(E), it is considered that the rotor has stepped out. be judged. If the deviation of the rotor angle is small, the operation is continued as it is because the tuning is normal.

Here, an example is shown in which the level of the drive current applied after the microtorque-up is the same as during rotation, but it may be higher or lower than during rotation. At least, the level of the drive current applied after the microtorque-up is lower than the level in the microtorque-up and higher than the level of the standby current.

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

FIG. 12 is a functional block diagram of the electric valve control device 200. As shown in FIG.
Each component of the electric valve control device 200 includes hardware (control circuit) including a control circuit (microcomputer) on the circuit board 118, storage devices such as memory and storage, and wired or wireless communication lines connecting them. It is implemented by software that is stored in a storage device and that supplies processing instructions to the calculator. Computer programs may consist of device drivers and application programs, as well as libraries that provide common functionality to these programs. Each block described below represents a functional block rather than a hardware configuration.

The electric valve control device 200 includes a data processing section 202 , a communication section 204 , a reference information storage section 206 and a rotor interface section 208 .
The communication unit 204 functions as an interface with an external device via the connection terminal 81 . Rotor interface section 208 functions as an interface for magnetic sensor 119 and coil unit 75 . The reference information storage unit 206 stores origin information (reference information). A reference information storage unit 206 is a storage area configured in a nonvolatile 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 . Data processing unit 202 also functions as an interface for communication unit 204 , rotor interface unit 208 and reference information storage unit 206 .

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.

Rotor interface portion 208 includes a rotation instructing portion 214 and a rotation detecting portion 216 . Rotation instruction unit 214 outputs a drive current to each of U-phase coil 73a, V-phase coil 73b, and W-phase coil 73c. The rotation detector 216 reads the duty ratio (angle value) from the current pulse received from the magnetic sensor 119 .

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

FIG. 13 is a flow chart showing the process of the electric valve control device 200. As shown in FIG.
When the receiving unit 210 receives a movement command (including the final step n(E)) from an external device (S10), the rotation control unit 218 determines the rotation direction and rotation speed according to the movement command. Since the final step n(E) is a step for stopping the rotor, it may be regarded as a stop step, a target step, or a movement destination step.

The rotation control unit 218 identifies the start step n(S) (S12). The starting step n(S) is for example the final step n(E) in the previous movement command. The rotation control unit 218 identifies the excitation pattern R(S) corresponding to the start step n(S) according to the correspondence relationship between the step n and the excitation pattern (S14). Rotation control unit 218 transmits the value of the drive current for each phase determined by excitation pattern R(S) to rotation instruction unit 214, and rotation instruction unit 214 applies these drive currents to the coils for each phase. The drive current at this time is at the same low level C(L) as the drive current applied during rotation (S16). This state is maintained until a predetermined first time elapses. The processing of S10 to S16 shown here corresponds to the start-up processing (see FIG. 11).

After the predetermined first time has elapsed, the rotation control unit 218 waits for the timing to proceed to the next step n(i) according to the predetermined rotation speed (S18). When the timing for advancing to the next step n(i) is reached, the rotation control unit 218 specifies the next step n(i) toward the end step n(E) (S20). The rotation control unit 218 identifies the excitation pattern R(i) corresponding to the next step n(i) according to the correspondence relationship 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). If it is determined that the next step n(i) is not the end step n(E), the rotation control unit 218 sends the value of the drive current for each phase determined by the excitation pattern R(i) to the rotation instructing unit 214. The rotation instructing unit 214 applies these drive currents to the coils of each phase. The drive current at this time is at a low level C(L). Then, the process returns to S18 and repeats the above-described processing.

On the other hand, when determining that the next step n(i) is the end step n(E), the rotation control unit 218 determines the excitation pattern R(E) corresponding to the end step n(E). The value of the driving current of each phase that is present is multiplied by a predetermined magnification (greater than 1) to obtain the driving current value of the high level C(H) that is applied before stopping. Then, the rotation control section 218 transmits the drive current value of the high level C (H) for each phase to the rotation instructing section 214, and the rotation instructing section 214 responds to the drive current value of the high level C (H) to the coil of each phase. ) is applied. That is, the driving current of each phase switches from the low level C(L) to the high level C(H) (S26). Since the low-level drive current values are multiplied by a common predetermined multiplier, the high level C(H) maintains the same ratio as the low-level drive current ratio of each phase.

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

When a predetermined third period of time has passed after switching to the low level C(L), the step-out detection unit 220 performs step-out detection processing (S30). In the out-of-step detection process, when the actual rotor angle measured using the magnetic sensor 119 deviates greatly from the ideal rotor angle targeted by the excitation pattern R(E) of the end step n(E), judged to be out of step. The criteria for out-of-step determination may be defined by the deviation of the rotor angle, or may be defined by the difference in the number of steps. The step number difference is uniquely determined based on the rotor angle deviation. When step-out occurs, a step-out error is notified to the external device. If there is no step-out, the rotation control section 218 notifies the rotation instructing section 214 of the standby current value for each phase, and the rotation instructing section 214 applies the standby current to the coil of each phase (S32). As a result, the process shifts to the standby process (see FIG. 11). The processing of S26 to S32 described above corresponds to the stop processing (see FIG. 11).

[Modification]
14(A) and 14(B) are diagrams showing the relationship between the step and the rotor angle in the modified example.
As shown in FIG. 14(A), the micro-torque-up may be started from step n(E-1) one time before the end step n(E). Alternatively, the micro-torque-up may be started from step n(i) a plurality of times before the end step n(E). In this way, if the micro-torque-up is started before the end step and continues until the end step n(E), the period during which the rotor 60 is strongly attracted to the ideal posture becomes longer. The rotor angle can be brought closer to the ideal rotor angle.

As shown in FIG. 14(B), micro-torque-up is performed at step n(E-1) one time before end step n(E), and micro-torque-up is not performed at end step n(E). may Alternatively, the micro torque-up may be started at step n(i) a plurality of times before the end step n(E) and finished before the end step n(E). If the actual rotor angle is brought closer to the ideal rotor angle before the end step n(E), the rotor 60 can be rotated in a posture close to the ideal rotor angle without micro-torque-up at the end step n(E). can be stopped.

Thus, the rotor 60 can be stopped in a posture close to the ideal rotor angle by performing the microtorque-up within a range close to the end step n(E). If micro-torque-up is performed before the end step n(E) by the number of steps smaller than the delay number of steps during rotation (3 in the example of FIG. 10(B)) explained in FIG. 10(B), the motor stops. The actual rotor angle at the time can be brought closer to the ideal rotor angle to some extent. For example, if the micro-torque-up is performed at step n (E-2), which is two steps before the end step n (E), the ideal rotor angle at step n (E-2) can be achieved, so FIG. 3, the rotor angle is closer to the ideal rotor angle than the actual rotor angle at the end step n(E) when the microtorque-up is not performed.

Further, if it is sufficient to suppress the deviation of the step to the extent that it is not determined to be out of step, micro torque up is performed before the end step n(E) by the number of times smaller than the difference in the number of steps when it is determined to be out of step. it's enough to go For example, if the micro torque is increased at step n (E-3), which is three steps before the end step n (E), the ideal rotor angle at step n (E-3) can be achieved. The number of delays is 3 or less. The specification for out-of-step determination is defined as out-of-step when the difference in the number of steps corresponding to the difference between the actual rotor angle when the rotor 60 stops and the ideal rotor angle of the end step n(E) is 4 or more. If such determination is made, it is possible to avoid determination of loss of synchronism.

In this way, at any step within a predetermined range from the step before the end step n(E) to the end step n(E), by performing the micro-torque-up at least once, the power consumption is suppressed and the rotor is rotated. The effect of increasing the accuracy of stopping is exhibited.

In the above-described embodiment, the configuration in which the magnetic sensor 119 faces the sensor magnet 106 in the axial direction is exemplified (see FIG. 1). In a modification, the magnetic sensor may be arranged laterally (outside in the radial direction) of the sensor magnet. That is, both may be opposed in the radial direction. The outer peripheral surface of the sensor magnet may be magnetized. The number of poles can be appropriately set, for example, two poles in the valve body.

In the above embodiment, the configuration in which the rotor magnet 104 and the sensor magnet 106 are separated in the axial direction is exemplified. In a modification, the rotor magnet and the sensor magnet may be integrated. In the magnet portion molding step, the rotor magnet portion and the sensor magnet portion may be integrally molded. In that case, the area (outer diameter) of the sensor magnet may be increased so that the magnetic sensor can reliably detect the magnetic flux. Since the sensor magnet protrudes outside the rotor core, injection molding of the sensor magnet and the rotor magnet is facilitated.

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

In each embodiment, the configuration in which the drive circuit, the control circuit, the communication circuit, and the power supply circuit are mounted on the lower surface of the circuit board is exemplified, but the circuits to be mounted can be changed as appropriate. For example, the drive circuit and power supply circuit may be implemented, while the control circuit may be located external to the motor operated valve. Also, each circuit may be mounted on the upper surface of the circuit board.

In each embodiment, a PM stepping motor is used as the motor unit, but a hybrid stepping motor may be used. Also, in the above embodiment, the motor unit is a three-phase motor, but other motors such as two-phase, four-phase, and five-phase motors may be used. The number of electromagnetic coils in the stator is not limited to three or six, and may be appropriately set according to the number of phases of the motor.

The motor-operated valve of each embodiment is suitably applied to a refrigeration cycle that uses a CFC substitute (HFC-134a) as a refrigerant, but it can also be applied to a refrigeration cycle that uses a refrigerant with a high operating pressure, such as carbon dioxide. is. In that case, an external heat exchanger such as a gas cooler is arranged in the refrigeration cycle instead of the condenser.

In each embodiment, the electric valve is configured as an expansion valve, but it may be configured as an on-off valve or a flow control valve that does not have an expansion function.

In each embodiment, an example in which the electric valve is applied to the refrigerating cycle of an automotive air conditioner is shown, but the electric valve is applicable not only to vehicles but also to air conditioners equipped with an electric expansion valve. Also, it can be configured as an electrically operated valve that controls the flow of fluid other than refrigerant.

1 in this embodiment is applicable not only to electric vehicles but also to various vehicles.

The sensor magnet 106 may be magnetized on both sides with four poles (double-sided magnetization with two poles on the single-sided valve main body). Magnetic flux can be strengthened by reversing the polarity of the magnetic poles on the top and bottom surfaces. 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 satisfactorily.

Reference Signs List 1 electric valve, 2 valve body, 3 motor unit, 5 body, 6 first body, 8 second body, 10 male thread, 12 seal housing portion, 14 seal ring, 16 concave fitting portion, 18 seal housing portion, 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 screw, 40 large diameter portion, 42 spring bearing, 44 spring bearing, 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, 80 seal housing, 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 portion 112 bottom portion 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 electric valve control device 202 data processing unit, 204 communication unit, 206 reference information storage unit, 208 rotor interface unit, 210 reception unit, 212 transmission unit, 214 rotation instruction unit, 216 rotation detection unit, 218 rotation control unit, 220 step-out detection unit

Claims (7)

An electric motor for controlling a motor-operated valve having a stepping motor that rotates a rotor by driving 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 to the axial motion of the valve body. A valve control device,
a rotation control unit that sequentially switches the steps when rotating the rotor, and specifies the drive current of each of the phases according to 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 maintains the ratio of the drive currents of the phases specified according to the excitation pattern before the rotating rotor stops, and maintains the drive currents of the phases at a level higher than that during the rotation. Determine the drive current,
The motor-operated valve control device, wherein the rotation instructing section applies the high-level drive current of each phase specified by the rotation control section to the stepping motor. In an end step of the steps that are sequentially switched during the rotation, the rotation control unit maintains the ratio of the drive currents of the phases specified according to the excitation pattern corresponding to the end step, and 2. The motor-operated valve control device according to claim 1, wherein said higher level drive current is specified than during said rotation. The rotation control unit maintains the ratio of the drive currents of the respective phases specified according to the excitation pattern corresponding to the preceding step in a preceding step close to the end step of the steps that are sequentially switched during the rotation, 3. The motor-operated valve control device according to claim 1, wherein for each of said phases, said higher level drive current than during said rotation is specified. 4. The electric valve control device according to claim 3, wherein the step difference between the preceding step and the end step is smaller than the step difference when it is determined that the stepping motor has stepped out. 4. The motor-operated valve control device according to claim 3, wherein a step difference between the preceding step and the ending step is smaller than the step delay number during the rotation. The rotation control unit identifies a drive current of a lower level than the high level drive current for each of the phases before putting the stepping motor into a standby state in the end step;
3. The motor-operated valve control device according to claim 2, wherein the rotation instructing section switches the high-level drive current applied to each phase to the low-level drive current in the end step. A computer that controls an electric valve having a stepping motor that rotates a rotor by driving current applied to each phase based on an excitation pattern corresponding to steps, and a mechanism that changes the rotary motion of the rotor into axial motion of the valve body. to the
a rotation control function for sequentially switching the steps when rotating the rotor, and specifying the drive current of each of the phases according to 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, before the rotating rotor stops, while maintaining the ratio of the drive currents of the phases specified according to the excitation pattern, each phase has a higher level than that during the rotation. Determine the drive current,
A motor-operated valve control program, wherein, in the rotation instruction function, the high-level drive current of each of the phases specified by the rotation control function is applied to the stepping motor.

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