JPH09285187A - Drive unit for stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to carry out adjustable-speed control without increasing the burden of treatment at control side by changing the rotation gently during ordinary forward and reverse rotations by revising excitation pattern to be used for power application to each phase of a stepping motor. SOLUTION: When control data transmitted from engine control ECU2 has changed from retention to open valve or from open valve to retention, a stepping motor 1b is rotated by 0.5 step in open valve direction; when a change occurs from retention to close valve or from close valve to retention, the stepping motor 1b is rotated by 0.5 step in close valve direction. When the control data are continuously open valve or already in open valve, the stepping motor 1b is rotated in 1 step unit for open valve or in open valve direction; if continuous retention occurs, the stepping motor 1b is stopped at that position. Thus, the stepping motor can be speed-adjusted adequately and step-out can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a step motor, a control section for generating control data for driving the step motor, and each step motor phase according to the control data generated by the control section. The present invention relates to a step motor control device, which is separated into a drive unit for energizing the motor and which is connected by a single communication line for transmitting control data.

[0002]

2. Description of the Related Art Conventionally, as a step motor control device, for example, as disclosed in Japanese Unexamined Patent Publication No. 5-164394, a step motor control system is divided into a control section and a drive section, and a stepping motor Is connected with one signal line,
Driving method of the step motor from the control side (forward / reverse rotation)
It has been proposed that the excitation data of the step motor be sequentially switched every time the drive section receives the control data by transmitting the control data representing the above in synchronization with the drive cycle of the step motor.

In the proposed device, the signal line between the control unit and the drive unit can be reduced to simplify the control system of the step motor. It is sufficient to sequentially command the rotation direction of
Since it is not necessary to consider the excitation pattern when driving the step motor, the processing load on the control unit side can be reduced. Therefore, this type of device can be used very effectively in a system that controls various actuators including a step motor on the control unit side.

[0004]

By the way, the step motor may be out of step when changing from a stopped state to a rotating state or vice versa, or when reversing the direction of rotation. For this reason, conventionally, when changing the driving method of the step motor, the excitation phase is switched more slowly than usual, and acceleration / deceleration control is performed to gradually increase or decrease the rotation speed of the step motor.

Therefore, in order to execute such conventional acceleration / deceleration control in a device in which the control system of the step motor is separated into a control unit and a drive unit like the above-mentioned proposed device, the control data must be set in the control unit side. The output cycle of must be changed. As a result, in the proposed device, the control system is separated into the control unit and the drive unit in order to reduce the processing load of the control unit, but the control unit controls the control data for the acceleration / deceleration control. However, there is a problem that the processing load of the control unit cannot be reduced sufficiently.

The present invention has been made in view of these problems, and in a device in which a control system of a step motor is separated into a control section and a drive section and the sections are connected by a single communication line, the control section side It is an object of the present invention to be able to execute acceleration / deceleration control when changing the driving method of the step motor without increasing the processing load.

[0007]

In the step motor control device according to claim 1 which has been made to achieve the above object, in the control section side, is the transmitting means driving the step motor in the forward direction? , Control data indicating whether to drive in the reverse direction or stop the rotation of the motor is generated at predetermined time intervals and sent to the communication line. At the drive unit side, the receiving means controls the sent control data. To receive. Then, on the drive unit side, the energization control unit energizes each phase of the step motor according to the control data received by the receiving unit to rotate the step motor forward, reverse, or stop, and the step represented by the received control data. When the driving method of the motor changes, the excitation pattern used for energizing each phase of the step motor is changed to change the rotation of the step motor more gently than during normal forward / reverse rotation.

Therefore, according to the present invention, in the control device in which the control system of the step motor is separated into the control section and the drive section and the two are connected by the communication line, the rotation direction of the step motor is reversed, The acceleration / deceleration control when changing from the stopped state to the rotated state or vice versa can be executed only on the drive unit side, and the processing load on the control unit side can be reduced. Therefore, according to the present invention, it is very effectively used in a control system in which not only a step motor but also other actuators are simultaneously controlled on the control unit side, as in the engine control system of the embodiment described later. be able to.

Here, as the energization control means in claim 1, as described in claim 2, the latest control data among the control data received by the receiving means and the control immediately before the latest control data. If the excitation phase to be energized is sequentially determined based on the data, it can be easily realized.

That is, specifically, when the control data is received, the latest received control data is compared with the previously received control data, and if the control data match,
When switching the excitation phase, the step motor rotation change amount is set to 1
When the control data is changed by performing either one-phase excitation or two-phase excitation corresponding to steps, the excitation phase is switched from the normal two-phase excitation (or one-phase excitation) to the one-phase excitation (or By switching to (two-phase excitation), the step motor is changed by a rotation amount for one step each time control data is received during normal rotation driving, and when the driving method is changed, the step motor is changed to 0. The rotation amount can be changed by 5 steps.

On the other hand, in the step motor control device according to the third aspect of the present invention, on the control unit side, the transmitting means drives the step motor in the forward direction only when it is necessary to rotate the step motor. Control data indicating whether to drive in the reverse direction is generated every predetermined time and sent to the communication line.

On the drive unit side, the receiving means receives the control data via the communication line, and the holding state determining means measures the time during which the excitation phase of the step motor is fixed. From this measured time, The holding state of the step motor is determined. Then, each time the receiving means receives the control data, the energization control means sequentially switches the excitation phase of the step motor according to the control data to rotate the step motor forward or reverse, and at the same time the determination result by the holding state determination means. Based on the received control data and the control data received, it is determined whether the driving method of the step motor has changed.When the driving method has been changed, the excitation phase of the step motor is set to an excitation pattern different from that in normal operation. Switching is performed, and the rotation of the step motor is changed more slowly than during normal forward / reverse rotation.

That is, in the step motor control device according to the third aspect of the present invention, in order to simplify the operation on the control side, the control data indicating the rotation direction is transmitted only when the step motor is rotated. I am trying. In such an apparatus, since the drive unit cannot detect the change in the drive method (that is, the change from the rotation of the step motor to the stop or vice versa) only by the control data, the drive unit side determines the holding state. A means is provided to detect the rotation stop (holding state) of the step motor, and the change in the step motor driving method is determined from the detection result and the control data.

Also in the step motor control device of the present invention, as in the case of the device according to claim 1, the drive section side determines a change in the step motor drive method, and an excitation pattern different from the normal state. By switching the excitation phase of the step motor with, the rotation of the step motor is changed more slowly than during normal forward / reverse rotation.Therefore, the acceleration / deceleration control when changing the method of driving the step motor is performed by the drive unit side. This can be executed only by, and the processing load on the control unit side can be reduced.

As the judging means, as described in claim 4, the elapsed time after the control data is received by the receiving means is measured, and the measured time is determined from the transmission cycle in which the transmitting means transmits the control data. When a long time is reached,
If the holding state of the step motor is judged, the judging means can be easily realized by using a timer circuit or the like.

That is, the holding state of the step motor can be determined from the switching state of the excitation phase by the energization control means (for example, a fixed time for keeping the excitation phase constant).
In this case, it is necessary to provide monitoring means for monitoring the switching operation of the excitation phase by the energization control means. On the contrary,
If the holding state of the step motor is judged from the elapsed time after receiving the control data as described in claim 4,
The holding state determining means can be easily realized only by a timer circuit for timing, etc., and the device configuration can be simplified.

Next, the energization control means of the present invention changes the stepping motor from the stopped state to the rotating state or vice versa, and in order to reverse the rotating direction, the stepping motor driving method (forward / reverse rotation) is used. When changing the (stop), the excitation phase of the step motor is switched with an excitation pattern different from the normal one so that the rotation of the step motor is changed more slowly than usual. For this purpose, as described above, the excitation method of the step motor is changed from the normal one-phase excitation to the two-phase excitation or the normal two-phase excitation.
This can be easily realized by changing the phase excitation to the one-phase excitation.

However, during normal driving (forward rotation / reverse rotation / stop), the step motor is driven by either one-phase excitation or two-phase excitation, and only when the method of driving the step motor changes. When the excitation method is changed, the number of times control data is transmitted from the control unit indicating the rotation command (forward / reverse rotation) and the amount of change in the step motor rotation position (step position) do not match. On the side, it is necessary to update the step position of the step motor from the number of transmissions of control data representing the rotation command and the number of times the driving method of the step motor is changed.

That is, for example, in an apparatus (claims 1 and 2) in which control data indicating forward / reverse rotation / stop of the step motor is transmitted from the control unit side, when the step motor is stopped from the rotating state, On the drive side, when the control data changes from the rotation command to the stop command, the step motor is rotated by 0.5 steps when the control data representing the stop command is received, and then the normal excitation method is restored. However, since the step motor also rotates by 0.5 steps at this time, the step motor rotates by one step more than the number of times the control data representing the rotation command is received. Therefore, in this case, if the control unit knows the step position of the step motor from the number of times the control data indicating forward / reverse rotation of the step motor is transmitted, the step motor recognized by the control unit There will be a difference between the step position of the step motor and the actual step position, and in order to accurately grasp the step position of the step motor on the control side, not only the number of times the control data is transmitted but also the step motor driving method is changed. It is necessary to update the step position of the step motor in consideration of the number of times of movement and the changing direction.

Therefore, as the communication control means, as described in claim 5, when the step motor is driven in the forward or reverse direction, the excitation phases are sequentially switched by the two-phase excitation, and when the rotation of the step motor is stopped, the one phase is switched. When the rotation of the step motor is maintained by excitation and the driving method of the step motor changes, it is desirable that the excitation phase of the step motor be changed by one-phase excitation immediately after that.

In other words, if the communication control means is configured in this way, the step motor can be normally rotated by one step and the step motor can be rotated by 0.5 step immediately after the driving method is changed. And moreover,
The rotation amount of the step motor when the step motor is changed from the rotation state to the stop state and the rotation amount of the step motor when the step motor is changed from the stop state to the rotation state are each 0.5 step. Can be the amount of rotation. Therefore, the step position of the step motor always coincides with the number of transmissions of the control data representing the rotation command from the control unit side, and the control unit side accurately determines the step position of the step motor only by the number of control data transmissions. Therefore, it is possible to simplify the processing operation for monitoring the step position of the step motor on the control unit side, and to reduce the processing load on the control unit side better.

In the apparatus according to the fifth aspect, the step motor is driven by two-phase excitation when the step motor is rotationally driven, and the step motor is driven by one-phase excitation when the rotation of the step motor is stopped. This is to reduce the power consumption for maintaining the step position of the step motor and to secure the driving torque when the step motor rotates.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an engine control system for a 4-cylinder 4-cycle engine will be described below with reference to the drawings. First, the overall configuration of the engine control system and the exhaust gas recirculation control system will be described with reference to FIG.

As shown in FIG. 1, the intake pipe 4 of the engine EG is provided with an air flow meter 5, a throttle valve 6, a surge tank 7 and the like. An intake air temperature sensor 8 for measuring the intake air temperature is attached near the air flow meter 5, and the throttle valve 6 has an idle switch 9 which is turned on when the throttle valve 6 is fully closed.
Is attached. Further, a bypass passage 30 that bypasses the throttle valve 6 and communicates with the throttle valve 6 is provided between the upstream side and the downstream side of the throttle valve 6, and the valve opening degree is controlled in the middle of the bypass passage 30 by a solenoid (not shown). An idle speed control valve (ISCV) 31 is installed. In addition, IS
The CV 31 is for adjusting the amount of air flowing through the bypass passage 30 according to the valve opening degree and controlling the idling speed during engine idle operation to the target speed.

The surge tank 7 is connected to the combustion chamber 35 of each cylinder of the engine EG via the intake manifold 32 and the intake valve 33. A fuel injection valve 36 for injecting and supplying fuel to each cylinder is attached to the intake manifold 32, and fuel is injected from the fuel injection valve 36 into an air flow passing through the intake manifold 32. Further, the combustion chamber 35 is connected to a catalyst device 39 via an exhaust valve 37 and an exhaust manifold 38.

The spark plug 4 is provided in the combustion chamber 35 of each cylinder.
2 are provided, and the high voltage from the igniter 40 that generates a high voltage for ignition is sequentially distributed to the spark plugs 42 of these cylinders via the distributor 41. Further, the distributor 41 is provided with a rotation angle sensor 43 that detects the rotation of the shaft and generates an engine speed signal at every 30 ° C., for example.
A water temperature sensor 44, which penetrates the engine block and detects the engine cooling water temperature, is provided at G.
It is provided so as to project inward. Furthermore, an O ₂ sensor 46 is attached to the exhaust manifold 38 so as to project inward, and the O ₂ sensor 46 detects the oxygen concentration (and thus the air-fuel ratio) in the exhaust gas before entering the catalyst device 39. It is made possible.

On the other hand, the exhaust manifold 38 upstream of the O ₂ sensor 46 and the surge tank 7 downstream of the throttle valve 6 are communicated with each other by an exhaust gas recirculation passage 48, and the exhaust gas recirculation passage 48 is further connected. Four
In the middle of 8, the EGR cooler 47 for lowering the temperature of the exhaust gas flowing in this passage and the exhaust gas recirculation valve (EG
RV) 1 is provided.

The EGRV 1 is constructed by rotating a valve body 1c for adjusting the opening of the exhaust gas recirculation passage 48 and a screw (not shown) connected to the valve body 1c.
Step motor 1 for adjusting the valve opening by displacing the valve up and down
b and the step motor 1b are connected to the engine control ECU 2
The step motor drive circuit 1a is driven according to a control signal input from the. That is, EGR
V1 converts the rotational movement of the step motor 1b into the vertical movement of the valve body 1c to adjust the valve opening.

In this embodiment, the step motor 1b is used.
In addition, a stepper motor having a bifilar winding four-phase structure is used. Further, the step motor 1b is provided with an urging member (for example, a compression spring) for returning the initial position so that the valve body 1c can be closed when it is not driven (that is, when the energization is cut off).

Then, the step motor drive circuit 1a is
Based on a control signal from the engine control ECU 2, the step motor 1b is driven to control the opening degree of the EGRV 1 (specifically, the valve body 1c), so that the EGR cooler 47 is controlled.
The flow rate of the exhaust gas that is input through the intake manifold 32 is controlled, and thereby the exhaust gas recirculation amount (EGR amount) to the intake manifold 32 is controlled.

Next, the engine control ECU 2 has a hardware configuration as shown in FIG. 2, the same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 2, the engine control E
CU2 is a microcomputer 20, engine control E
A power supply circuit 21 for supplying power inside the CU2, an input interface circuit 22 for inputting an analog signal, and ON
The input / output interface circuit 23 inputs / outputs a / OFF signal (digital binary signal).

The microcomputer 20 includes a central processing unit (CPU core) 20a, a read only memory (ROM) 20b storing a processing program and control constants, and a random access memory (RAM) 20c used as a work area. , Ignition switch 3 OFF
A backup RAM 20d that holds data even after that, an A / D converter 20e with a multiplexer that converts an analog signal into digital data, an input / output port 20f that inputs / outputs an ON / OFF signal, a clock oscillator that supplies a master clock to the CPU core 20a 20g, and each part other than the clock oscillator 20g has a bidirectional bus line 20.
connected by h. Clock generator 20g
Is an oscillator equipped with a crystal oscillator 20i.

Engine control ECU configured as described above
2, the detection signals from the air flow meter 5, the intake air temperature sensor 8, the water temperature sensor 44, the O ₂ sensor 46, and the battery voltage VB are input to the A / D converter 20e through the input interface circuit 22. After being converted into digital data, the data is sequentially transmitted to the bus line 20h. The detection signal from the idle switch 9 and the engine speed detection signal from the rotation angle sensor 43 are transmitted to the bus line 20h through the input / output interface circuit 23. And igniter 4
0, the fuel injection valve 36, the ISCV 31, and the step motor drive circuit 1a, a predetermined control signal is transmitted from the CPU core 20a through the bus line 20h, the input / output port 20f, and the input / output interface circuit 23.

In this embodiment, the engine control ECU
2 and the stepping motor drive circuit 1a include one communication line L
The engine control ECU 2 drives the step motor 1b in the valve opening direction of the EGRV1 or drives the step motor 1b in the valve closing direction of the EGRV1 as a control signal for the step motor drive circuit 1a. Alternatively, the rotation of the step motor 1b is stopped and the EGR is performed.
Control data indicating whether to keep V1 at the current valve opening is generated.

Next, the step motor drive circuit 1a for opening and closing the EGRV 1 according to the control data transmitted from the engine control ECU 2 has a hardware configuration as shown in FIG. That is, the step motor drive circuit 1a
Is a power supply circuit 11, which is connected to the ignition switch 3 and supplies power to the inside of the step motor drive circuit 1a.
An input interface circuit 12 for inputting control data from the engine control ECU 2, a decoding circuit 13 for restoring control data from the engine control ECU 2 into data representing a driving method (valve opening / closing / holding) of the step motor 1b,
It is composed of a control circuit 14 for switching the excitation phase of the step motor 1b according to this data, and an output stage circuit 15 for energizing the step motor 1b based on an output signal from the control circuit 14.

Further, each phase φ1 to φ of the step motor 1b
The battery voltage VB is applied to one end of the winding of No. 4 via the ignition switch 3, and the control circuit 14
Switches the excitation phase by switching whether or not the other end of each phase winding is grounded via a switching element provided in the output stage circuit 15.

That is, the output stage circuit 15 includes NPN type transistors Tr1 to Tr4 each having a collector connected to the other end of each phase winding of the step motor 1b and a grounded emitter, as switching elements. A drive signal (Hi signal output from the control circuit 14 for each phase φ1 to φ4) that is connected to the bases of the transistors Tr1 to Tr4
gh / Low), these transistors Tr1 to T
The control circuit 14 includes input resistors R11 to R41 and ground resistors R12 to R42 for turning on and off r4.
The step motor 1b is driven by switching the ON / OFF state of each of the transistors Tr1 to Tr4 by the drive signal output to the output stage circuit 15.

As shown in FIG. 4, the output stage circuit 15
Is provided with diodes D1 to D4 whose anodes are connected to the collectors of the respective transistors Tr1 to Tr4 and resistors R13 to R43 which connect the cathodes of the diodes D1 to D4 to the power supply line. The D1 to D4 and the resistors R13 to R43, when the transistors Tr1 to Tr4 are switched from ON to OFF (that is, when the energization to each phase winding is cut off), charge the high voltage generated in each phase winding. This is what constitutes a so-called regenerative circuit that is returned to the power supply side.

Next, the process for driving the step motor 1b, which is the main process relating to the present invention and executed in the engine control system of the present embodiment configured as described above, will be described in detail. The engine control E
The CU 2 repeatedly transmits control data indicating a driving method (valve open / valve / hold) of the step motor 1b to the step motor drive circuit 1a. In this case, for example, as shown in FIG. , Control data is composed of serial data consisting of a low-level fixed start bit, 0-bit to 7-bit 8-bit data, and a high-level fixed stop bit.
It is also possible to execute serial communication by transmitting this serial data from U2 every predetermined period To, or, for example, as shown in FIG. 5 (b), control data can be transmitted within a preset fixed time T2. , A PWM signal (pulse width modulation signal) in which the ratio (duty ratio) of the time T1 at which the low level (or the high level is acceptable) is controlled according to the data content (that is, the driving method of the step motor 1b) is used. It is also possible to execute PWM communication in which the PWM signal is repeatedly transmitted from the control ECU 2.

First, in the engine control ECU 2, as a control process for driving the step motor 1b, E
The EGR control process for controlling the opening degree (and thus the EGR amount) of the GRV1 is executed every calculation cycle (for example, 4 msec.) Corresponding to the pulse rate during the fastest operation of the step motor 1b. The EGR control process corresponds to the transmitting means of the present invention.

As shown in FIG. 6, in this EGR control process, first in S110 (S: represents a step which is a processing procedure), an EGR control prohibition flag for prohibiting the execution of the EGR control in an abnormality determination process not shown is set. It is determined whether the prohibit flag is set or not. If the prohibit flag is not set, the process proceeds to S120, and if the prohibit flag is set, the process proceeds to S130.

Here, the EGR control prohibition flag is output from the engine control ECU 2 by an abnormality determination process separately executed in the engine control ECU 2 due to a failure of the EGRV 1 or a failure of the EGR system due to clogging of the pipe of the exhaust gas recirculation passage 48 or the like. When it is determined that the EGR amount cannot be controlled even when the control data is transmitted to the step motor drive circuit 1a, and when the control system other than the EGR system fails, such as when the water temperature sensor fails, the EGR control cannot be normally executed. This flag is set when it is determined that

That is, in the abnormality determination processing, for example, EG
The RV1 is changed from the open state to the closed state (or vice versa), and it is determined whether the EGR amount is changed or not depending on whether the detection signal from the air flow meter 5 is changed at that time, and the EGR amount is changed. If is not changed, it is determined that the EGR system is out of order, and EGR control is prohibited.
Set the GR control prohibition flag. Also, the water temperature sensor 4
Failure determination is also performed on other components other than the EGR system, such as 4, and the EGR control prohibition flag is set even when a component that affects the execution of EGR control is defective. Then, in S110, the EGR
If the control inhibition flag is set, the process proceeds to S130 to inhibit the EGR control.

The failure of the EGR system can be determined by the above procedure only when the operating condition of the engine EG is constant.
If the EGR amount increases, the intake air amount passing through the air flow meter 5 decreases, and conversely, if the EGR amount decreases, the intake air amount passing through the air flow meter 5 decreases. Because it will increase.

Next, in S120, for example, the battery voltage is equal to or higher than a predetermined voltage (eg, 10 V), the cooling water temperature is equal to or higher than a predetermined temperature (eg, 60 ° C.) after engine warm-up, and the idle switch 9 is turned off (that is, The engine is in a non-idle state and the vehicle speed is a predetermined speed (for example, 2 h
It is determined whether all preset EGR control execution conditions such as (e.g., km or more) are satisfied, and if all of these EGR control execution conditions are satisfied, S140
If, on the contrary, even one of the EGR control execution conditions is not satisfied, the process proceeds to S130.

Then, in S130, EGRV1 is set to EG
A target step TSTEP indicating the target rotational position of the step motor 1b for controlling the fully closed state without executing the R control.
Is set to an initial value "0", and the process proceeds to S150. Further, in S140, E is changed according to the operating state of the engine EG.
In order to control the opening degree of GRV1 (in other words, EGR amount),
The target step TSTEP of the step motor 1b is calculated based on the operating state of the engine EG, and the process proceeds to S150.

Next, in S150, S130 or S14.
The target step TSTEP set at 0 and the current step EST indicating the current rotational position of the step motor 1b
It is determined whether or not EP matches, and TSTEP = E
If it is STEP and the EGRV1 is already controlled to the target opening degree, the process proceeds to S160 to stop the rotation of the step motor 1b and hold the rotational position at the current position, and the step motor drive circuit Control data representing "holding" is transmitted to 1a as the driving method of the step motor 1b, and the step motor 1b is turned on in step S170.
The valve opening mode flag FOPEN indicating that the GRV1 is driven in the valve opening direction and the step motor 1b are set to EGR.
After resetting the valve closing mode flag FCLOSE indicating that the valve is being driven in the V valve closing direction, the process ends.

Further, in S150, the target step TSTE
If it is determined that P does not match the current step ESTEP, the process proceeds to S180 and the target step T
It is determined whether STEP is smaller than the current step ESTEP. If the target step TSTEP is larger than the current step ESTEP and it is necessary to drive the step motor 1b in the opening direction of the EGRV1, S
At 190, it is determined whether the valve closing mode flag FCLOSE is set, and the valve closing mode flag FCLOS is determined.
If E is set, the step motor 1b has been driven in the closing direction of the EGRV1 so far, and if the rotation direction of the step motor 1b is reversed to the opening direction as it is, step-out may occur. In order to temporarily stop and hold at the current position, the process shifts to S160, control data representing "hold" is transmitted, and then S170 is continued.
Then, after resetting both the valve opening mode flag FOPEN and the valve closing mode flag FCLOSE, the process ends.

On the other hand, in S190, the valve closing mode flag F
When it is determined that CLOSE is reset, that is, when the step motor 1b has been stopped (held) or has been driven in the opening direction, the step motor 1b is driven in the opening direction. However, step-out does not occur, so in step S200, the current step ES is performed to drive the step motor 1b in the opening direction by one step.
Increment the TEP value (increase by one step)
After that, in S210, control data representing "valve open" is transmitted as the driving method of the step motor 1b. And
In subsequent S220, in order to store the driving of the step motor 1b in the valve opening direction, the valve opening mode flag FOPEN is set and the valve closing mode flag FCLOSE is reset, and then the process ends.

Next, at S180, the target step T
If STEP is currently smaller than step ESTEP and it is determined that the step motor 1b needs to be driven in the closing direction of EGRV1, the process proceeds to S230 to check whether the valve opening mode flag FOPEN is set. If it is determined that the valve opening mode flag FOPEN has been set, the step motor 1b has been driven in the opening direction of the EGRV1 so far, and if the rotation direction of the step motor 1b is reversed to the closing direction as it is, step-out occurs. Therefore, in order to stop the step motor 1b and hold it at the current position, the process proceeds to S160, control data representing "hold" is transmitted, and in the subsequent S170, the valve opening mode flag FOPEN, closed. After resetting the valve mode flag FCLOSE together, the process ends.

On the other hand, in S230, the valve opening mode flag F
When it is determined that OPEN is reset, that is, the rotation of the step motor 1b has been stopped (held) until now.
Was driven or was driven in the closing direction,
Even if the step motor 1b is driven in the closing direction, step-out does not occur. Therefore, in step S240, the current step ESTE is performed to drive the step motor 1b in the closing direction by one step.
After decrementing the value of P (decreasing by one step), in S250, control data representing "valve closed" is transmitted as the driving method of the step motor 1b. Then, in subsequent S260, in order to store the driving of the step motor 1b in the valve closing direction, the valve closing mode flag FCLOSE is set, the valve opening mode flag FOPEN is reset, and then the process ends.

As described above, in the engine control ECU 2, whether the EGR control is prohibited by executing the EGR control process every predetermined time (for example, 4 msec.) According to the pulse rate at the fastest operation of the step motor 1b. Or E
If the execution condition of the GR control is not satisfied, the initial value "0" is set to the target step TSTEP of the step motor 1b to prohibit the execution of the EGR control, the EGR control is not prohibited, and the EGR control is not performed. If the execution condition of is satisfied, EGRV is changed according to the operating state of the engine EG.
A target step TSTEP of the step motor 1b for controlling 1 to a predetermined opening degree is set. And then
In order to control the step motor 1b to this target step TSTEP, the driving method (valve opening / closing / holding) of the step motor 1b is set, and control data representing the driving method is transmitted to the step motor driving circuit 1a. .

As described above, the engine control ECU 2
From the step motor drive circuit 1a to the step motor 1
In transmitting the control data indicating the driving method of b,
When transmitting the serial data shown in FIG. 5A, as shown in FIG. 7, for example, 0 of 8-bit data is transmitted.
"Open" with serial data in which only the first bit is set to High level, and only the first bit of 8-bit data is set to Hi
Data indicating "valve closed" by serial data having a gh level and "holding" by serial data having only a second bit of the 8-bit data as a high level may be transmitted.

Further, when the PWM signal shown in FIG. 5B is transmitted, as shown in FIG. 8, for example, with the calculation cycle as one cycle, the duty ratio P within the range of 0 to 33% is set.
"Open valve" with WM signal, "close valve" with PWM signal of duty ratio within the range of 33 to 66%, 66 to 100%
"Hold" by the PWM signal with the duty ratio within the range of
The data representing each may be transmitted. However, in this case, it is necessary to prevent the duty ratios of the respective data from overlapping.

Next, FIG. 9 shows a step motor drive circuit 1a.
4 is a flowchart showing the operation of the control circuit 14 in the above.
As shown in FIG. 9, in the control circuit 14, when the internal power supply from the power supply circuit 11 rises, in S300, an initialization process for initializing a 3-bit counter or the like described later is executed. Then, in the subsequent S310, by determining whether or not the latest communication data is input from the decoding circuit 13 side, waiting for the communication data to be input, and when the communication data is input, it is determined in S320. Read communication data. That is, in the step motor drive circuit 1a, the control data from the engine control ECU 2 is received by the input interface circuit 12 as a receiving unit, and the control data is restored by the decoding circuit 13 to restore the control circuit 1
4, the communication data is read every time the restored latest communication data is input.

Next, in subsequent S330, it is determined whether or not the communication data read in S320 is data representing "hold" as the driving method of the step motor 1b, and the communication data represents data representing "hold". If so, the process proceeds to S460, and if the communication data is not data indicating "hold",
In step S340, it is determined whether the communication data is data indicating "open valve".

Then, if it is determined in S340 that the communication data is data indicating "open", the drive direction flag X indicating the drive direction of the step motor 1b is determined in S350.
Set OPEN, reset XCLOSE, S3
If the communication data indicates that the valve is closed, the drive direction flag XOPEN is reset and XCLOSE is set in S360, and the process proceeds to S370.

In S370, it is determined whether the latest communication data read in this time in S320 has changed from the communication data read in the previous time, the communication data has changed, and the step motor 1b is currently in the stopped state ( If it is the rotation start timing to change the rotation state (holding) to the rotation state (valve opening or closing), the process proceeds to S430, and conversely, the communication data has not changed and the step motor 1b is closed as in the previous time. When the valve or the valve is opened, the process proceeds to S380.

Then, in S380, the drive direction flag X
The drive direction of the step motor 1b is determined by determining whether OPEN is set, and the drive direction flag XOPEN is set.
If it is necessary to drive b in the valve opening direction, S390
After the 3-bit counter for determining the excitation phase is incremented by 2 (+2), the process proceeds to S410, and conversely the drive direction flag XOPEN is reset, and it is necessary to drive the step motor 1b in the valve closing direction. In some cases, the 3-bit counter is counted down by the value 2 (-2) in S400, and then the process proceeds to S410. Next, S
At 430, the driving direction of the step motor 1b from the stopped state is determined by determining whether the driving direction flag XOPEN is set, and the driving direction flag X is determined.
When OPEN is set and the step motor 1b is driven in the valve opening direction from the stopped state, the 3-bit counter is incremented by 1 (+1) in S440, and then the process proceeds to S410 and vice versa. Direction flag XOP
When EN is reset and the step motor 1b is driven in the valve closing direction from the stopped state, in S450, 3
After counting down the bit counter by 1 (-1), the process proceeds to S410.

On the other hand, the communication data is "held" in S330.
S4 executed when the data is determined to be
At 60, the drive direction flags XOPEN and XCLOSE are both reset and the process proceeds to S470. Also S470
Then, it is determined whether the latest communication data read in S320 this time has changed from the communication data read last time, the communication data has changed, and the step motor 1b is currently in a rotating state (opened or closed). If it is the rotation stop timing to change from the valve) to the stopped state (hold),
On the contrary, if the communication data has not changed and the rotation of the step motor 1b is stopped (time keeping) as in the previous case, it is not necessary to change the excitation phase, so the process returns to S310. Transition.

Then, in S480, the driving direction of the step motor 1b up to now is judged by judging whether or not the driving direction flag memory XOPEN is set, and the driving direction flag memory XOPEN is set. If the step motor 1b has been driven in the valve opening direction so far, the 3-bit counter is incremented by 1 in step S490 (+1), and the process proceeds to step S410. Conversely, the drive direction flag memory XOPEN is reset. If the step motor 1b has been driven in the valve closing direction so far, the 3-bit counter is counted down (-1) by 1 in S500, and then the process proceeds to S410.

Next, S390, S400, S44
At S410, which is executed after the value of the 3-bit counter is updated at 0, S450, S490, or S500, drive direction flags XOPEN and X based on the latest communication data are transmitted.
CLOSE to the memory area XOPEN,
Store in XCLOSEL. Then, in S420, 3
Based on the value of the bit counter, the excitation phase to be energized in the step motor 1b is set, a drive signal corresponding to the set excitation phase is output to the output stage circuit 15, and the S signal is output again.
Move to 310.

For setting the excitation phase, preset excitation pattern data as shown in FIG. 10 is used. That is, in the present embodiment, as is clear from FIG. 10, if the count value of the 3-bit counter is “0”, φ
If only one phase of 1 is the excitation phase and the count value is "1", then the two phases φ1 and φ2 are the excitation phase and the count value is "2"
If so, only one phase of φ2 is set as the excitation phase, if the count value is “3”, two phases of φ2 and φ3 are set as the excitation phase, and if the count value is “4”, only one phase of φ3 is set as the excitation phase. If the count value is “5”, the two phases φ3 and φ4 are the excitation phases, if the count value is “6”, only one phase φ4 is the excitation phase, and if the count value is “7” The two phases φ4 and φ1 are used as excitation phases, and the step motor 1b is energized.

As described above, in the step motor drive circuit 1a of the present embodiment, the control data transmitted from the engine control ECU 2 is data representing "open valve" or "close valve" continuously, EGR the motor 1b
When rotationally driving V1 in the valve opening or closing direction, the 3-bit counter is incremented or decremented by the value 2 according to the rotational direction of the step motor 1b, and the control data is changed from "retention" to "open". When the data changes to "valve" or "valve closed" or vice versa, the 3-bit counter is incremented or decremented by the value 1 according to the rotation direction when the step motor 1b is driven.

Therefore, first, after starting the control, with the 3-bit counter set to the initial value "0", the EGRV
In order to open 1 to a predetermined opening, the engine control ECU
When the control data 2 indicates “open valve” is repeatedly transmitted at a predetermined cycle (4 msec. In this embodiment), the count value of the 3-bit counter becomes “1” when the first control data is received, and thereafter. ., In synchronization with the input of the control data, the sequence is sequentially changed from “3” → “5” → “7” → “1” → “3”. As a result, the step motor 1b is rotated by 0.5 steps immediately after the driving is started, and thereafter, is rotated in the opening direction by one step by two-phase excitation in synchronization with the input of the control data. Become.

Next, when control data representing "hold" is output from the engine control ECU 2 in order to hold the opening degree of EGRV1, the count value of the 3-bit counter becomes a value when the first control data is received. The count value is incremented by 1, the count value becomes an even number, and thereafter, this count value is held. Therefore, when the control data changes from "valve open" to "keep time", the step motor 1b
Is driven in the opening direction for 0.5 steps, and then stops at the rotation position at that time by one-phase excitation.

When the engine control ECU 2 transmits control data representing "open" or "closed" to drive the step motor 1b in the valve opening or closing direction of the EGRV 1 from such a stopped state, The count value of the 3-bit counter is incremented or decremented by the value 1 according to the rotation direction of the step motor 1b when the first control data is received, and then incremented or decremented by the value 2. Therefore, when the control data changes from "hold" to "valve open" or "valve close", the step motor 1b rotates in the opening or closing direction by 0.5 steps only when the first control data is input. After that, by two-phase excitation, it rotates in the opening or closing direction in steps of one step.

That is, in the step motor drive circuit 1a of this embodiment, as shown in FIG.
The control data sent from "hold" to "open"
Or, when changing from "open" to "hold", the step motor 1b is rotated by 0.5 steps in the opening direction, and the control data changes from "hold" to "close" or "close". When changing to "hold", the step motor 1b is rotated in the valve closing direction by 0.5 steps, and when the control data is continuously "open" or "closed", The step motor 1b is rotated in the valve opening direction or the valve closing direction step by step, and when the "control data is continuously" keeping time ", the step motor 1b is stopped at that position.

Therefore, according to the present embodiment, FIG.
As shown in, when the driving method of the step motor 1b changes (time t1, time t4, time t5), the step motor 1b rotates by 0.5 steps, and when the step motor 1b continuously rotates (time t2. ~ T3, time t6 ...)
In addition, since the step motor 1b rotates in steps, the step motor 1b can be favorably accelerated and decelerated when the driving method is changed, and step-out can be prevented. That is, as shown in FIG. 12B, the engine control E
When the step motor 1b is driven by two-phase excitation using the control data from the CU2 as it is, when the step motor 1b is changed from the stopped state to the rotating state or vice versa, the step motor 1b is Since it rotates in units of one step depending on the transmission cycle of the control data from the engine control ECU 2, it is easy to get out of step. However, according to the present embodiment, the step motor 1b is rotated from the stopped state to the rotated state or Since the rotation of the step motor 1b at the time of changing it to the opposite direction can be gently changed, the step motor 1b can be stably driven without causing step-out.

Further, in this embodiment, when the control data is "holding time", the step motor 1b is held by one-phase excitation, and when the control data is "valve open" or "closed", the step motor 1b is held. Is rotated by two-phase excitation, the excitation method of the step motor 1b is switched from two-phase excitation to one-phase excitation when the driving method of the step motor 1b changes on the step motor drive circuit 1a side. Although the rotation amount is suppressed from 1 step to 0.5 step, the step position when the step motor is stopped is determined by the control data from the engine control ECU 2 that indicates “open valve” or “close valve”. The number of transmissions matches the number of transmissions (see FIG. 12), and the engine control ECU 2 side accurately grasps the rotational position of the step motor 1b from the number of transmissions of control data. Door can be.

Therefore, according to the present embodiment, on the engine control ECU 2 side, control data for instructing the rotation direction and stop of the step motor 1b may be generated, and the processing for energization control of the step motor 1b is performed at all. Since it is not necessary, the load of processing for EGR control on the engine control ECU 2 side can be reduced, and other processing for engine control can be executed without problems.

Here, in the above-described embodiment, the engine control ECU 2 as the control unit causes the step motor drive circuit 1a as the drive unit to open the step motor 1b.
Although the engine control system configured to transmit the control data indicating the valve closing / holding has been described, the engine control ECU 2 instructs the step motor drive circuit 1b to
Even when only the control data indicating the valve opening / closing of the step motor 1b is transmitted, the present invention can be applied to obtain the same effect as the above embodiment.

Then, next, as a second embodiment of the present invention,
From the engine control ECU 2 to open the step motor 1b
An engine control system will be described in which only control data representing the valve closing is transmitted. When configuring the engine control system of this embodiment, the engine control EC
On the U2 side, in the EGR control process shown in FIG. 6, it suffices not to execute the transmission output of the "hold" data in step 160 (that is, the process in step 160 is deleted), and the other configuration of the engine control ECU 2 Can be exactly the same as the above-mentioned embodiment, so the engine control ECU
The description of 2 is omitted.

On the other hand, the step motor drive circuit 1a, as shown in FIG. 13, has the power supply circuit 11, the input interface circuit 12, the decode circuit 13, and the control circuit 1 shown in FIG.
4 and the output stage circuit 15, a step holding determination circuit 16 is provided.

The step holding determination circuit 16 measures the elapsed time after receiving the control data based on the data input signal generated when the input interface circuit 12 receives the control data, and from the measured time, the step motor The drive circuit 1a is for judging that the rotation of the step motor 1b is stopped and the holding state for holding the rotation position is entered, and is configured as shown in FIG. 14 (a).

That is, the step hold determination circuit 16 is cleared (count value: 0) by the input of the data input signal, and counts the clock signal input at a constant cycle via the OR circuit 16b to obtain the data input signal. Measures the elapsed time after input (that is, after receiving control data),
A timer circuit 16a that generates a determination signal when the time (count value) reaches a predetermined determination time (predetermined count value) To and a determination signal from this timer circuit 16a are delayed by a predetermined time ΔT. , A delay circuit 16c that outputs the signal as a holding state signal.
The determination signal from the timer circuit 16a is input to the clock input terminal of the timer circuit 16a via the OR circuit 16b together with the clock signal for clocking, so that the timer circuit 16a outputs the determination signal. Medium, stop counting operation.

In the step holding determination circuit 16 thus configured, as shown in FIG. 14B, the engine control ECU 2 "opens" or "opens" or "closes" the valve so as to drive the step motor 1b in the opening direction or the closing direction. When the control data representing "closed valve" is repeatedly transmitted, the determination signal output from the timer circuit 16a is cleared before the count value of the timer circuit 16a reaches the predetermined value corresponding to the determination time To. It is held at the low level, but if the next control data is not received even after the judgment time To has passed after receiving the control data, it is judged that the step motor 1b is in the holding state, and the timer circuit 16a outputs the high level. Is output. Then, this determination signal is further delayed by a predetermined time ΔT in the delay circuit 16c, and the delayed determination signal is output to the control circuit 14 as a holding state signal.

The determination circuit output from the timer circuit 16a is delayed by the delay circuit 16c for a predetermined time ΔT because the control circuit 14 includes the input interface circuit 1
2 receives the control data, and after the decoding circuit 13 processes the data, the communication data in which the control data is restored is input. Therefore, the data input signal from the input interface circuit 12 clears the timer circuit 16a. The control circuit 14 uses the determination signal as it is as the holding state signal.
Input to the control circuit 14, communication data is input to the control circuit 14 after the hold status signal is inverted to the low level. Based on the communication data and the hold status signal, the control circuit 14 holds the hold status of the step motor 1b. This is because it may be impossible to determine the change from the rotation state to the rotation state.

That is, in this embodiment, when the control signal for driving the step motor 1b is received by delaying the determination signal from the timer circuit 16a by the delay circuit 16c, the communication data corresponding to the control data is received. After being input to the control circuit 14, the holding state signal is changed to a low level so that the control circuit 14 side can reliably determine the change from the holding state of the step motor 1b to the rotating state.

Next, FIG. 15 is a flow chart showing the operation of the control circuit 14 of this embodiment. As shown in FIG.
In the control circuit 14, the power supply circuit 1
At the time when the internal power supply from 1 is turned on, in S600, an initialization process for initializing a 3-bit counter and the like described later is executed. Then, in subsequent S610, it is determined whether or not the holding state signal from the step holding determination circuit 16 rises, and when the holding state signal rises, that is, after the control data is received, a predetermined time To + ΔT has elapsed, When the holding state in which the rotation of the step motor 1b is stopped is entered, the process proceeds to S720.

On the other hand, if the holding state signal has not risen, that is, the holding state signal is already at the high level,
If the holding state of the step motor 1b continues, or the holding state signal is at low level,
If b is being driven, the process proceeds to S620, and it is determined whether the latest communication data has been input from the decoding circuit 13 side. If the latest communication data has not been input, the process proceeds to S610 again. That is, in S610 and S620, the process waits until the holding state signal of the step motor 1b rises and the holding state signal rises, or control data is received and communication data after restoration is input.

When it is determined in S620 that the communication data is input, the data is read in S630, and in the subsequent S640, the read communication data is data representing "open valve". Determine whether or not. If the communication data is data indicating "open valve", S
At 650, the drive direction flag XOPEN is set, and S
If the communication data indicates that the valve is closed, the drive direction flag XOPEN is reset in S660, and then the process proceeds to S670.

In S670, whether or not it is the rotation start timing for changing the step motor 1b from the stopped state (holding) to the rotating state (opening or closing) depending on whether the holding state signal is at the High level or not. To judge. If the holding state signal is at the high level and the rotation start timing is currently reached, the process proceeds to S720. Conversely, if the holding state signal is at the low level, the step motor 1b is currently rotated in the valve opening or closing direction. If it is in the middle of making it, S6
Move to 80.

Then, in S680, the drive direction flag X
Determine the drive direction of the step motor 1b from OPEN,
When the drive direction flag XOPEN is set and the step motor 1b needs to be driven in the valve opening direction, S6
After the 3-bit counter is counted up by 2 (+2) at 90, the process proceeds to S710, and conversely, the drive direction flag XOPEN is reset, and if it is necessary to drive the step motor 1b in the valve closing direction, S700 is performed. At 3
After the bit counter is counted down by the value 2 (-2), the process proceeds to S710.

On the other hand, in S720, the driving direction flag XO
If the drive direction of the step motor 1b is determined from the PEN and the drive direction flag XOPEN is set, and the drive direction of the step motor 1b is the valve opening direction, the 3-bit counter is incremented by 1 in S730 (+1).
After that, the process proceeds to S710, and conversely the drive direction flag XOPE
If N is reset and the driving direction of the step motor 1b is the valve closing direction, the 3-bit counter is counted down (-1) by 1 in S740, and then the process proceeds to S710.

Then, in S710, S4 of the above embodiment is executed.
Similar to 20, S690, S700, S730 or S74
Based on the value of the 3-bit counter after being updated by 0, an excitation phase to be energized in the step motor 1b is set, a drive signal corresponding to the set excitation phase is output to the output stage circuit 15, and the process proceeds to S610 again. .

As described above, the engine control ECU
When the control data indicating the rotation direction (valve opening / closing) of the step motor 1b is transmitted only when the step motor 1b is rotationally driven, the step motor drive circuit 1a side proceeds after the control data is input. If the holding state of the step motor 1b is judged from the time and the change of the driving method of the step motor 1b is judged from the judgment result (holding state signal) and the received control data, similar to the above-described embodiment. , When the driving method of the step motor 1b is changed, the step motor 1b is rotated by 0.5 step by one-phase excitation, and during normal rotation drive, the step motor 1b is rotated by one step by two-phase excitation. Since it can be rotated, the same effect as that of the above embodiment can be obtained.

Although the engine control system for executing the EGR control by using the step motor 1b has been described as the embodiment of the present invention, the present invention is not limited to such an engine control system, and the control of the step motor is not limited thereto. A communication type step motor, in which the system is separated into a control unit for instructing the driving method of the step motor and a drive unit for energizing the step motor according to a command from the control unit, and a connection between them is connected by one communication line. If it is a control device, the present invention can be applied to obtain the same effects as those of the above-described embodiments.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of an engine control system and an exhaust gas recirculation control system of an engine control system according to an embodiment.

FIG. 2 is a block diagram showing a configuration of an engine control ECU.

FIG. 3 is a block diagram showing a configuration of a step motor drive circuit.

FIG. 4 is an electric circuit diagram showing a configuration of an output stage circuit for driving a step motor.

FIG. 5 is an explanatory diagram illustrating serial data and PWM signals that can be used as control data.

FIG. 6 is a flowchart showing an EGR control process executed in an engine control ECU.

FIG. 7 is an explanatory diagram illustrating an example of a data configuration when transmitting control data by serial communication.

FIG. 8 is an explanatory diagram illustrating an example of a data configuration when transmitting control data by PWM communication.

FIG. 9 is a flowchart illustrating a processing operation of a control circuit in the step motor drive circuit.

FIG. 10 is an explanatory diagram illustrating excitation pattern data used when switching an excitation phase of a step motor according to a count value of a 3-bit counter.

11 is an explanatory diagram illustrating a rotation amount of a step motor determined by a combination of control data by the processing shown in FIG.

FIG. 12 is a time chart showing changes in the step position of the step motor with respect to control data.

FIG. 13 is a block diagram showing the configuration of a step motor drive circuit according to a second embodiment.

FIG. 14 is an explanatory diagram illustrating a configuration and operation of the step holding determination circuit shown in FIG.

FIG. 15 is a flowchart illustrating a processing operation of a control circuit in the step motor drive circuit of the second embodiment.

[Explanation of symbols]

EG ... Engine 2 ... Engine control ECU 20 ...
Microcomputer 23 Input / output interface circuit 38 Exhaust manifold 7 Surge tank 47 EGR cooler 48 Exhaust gas recirculation passage 1 Exhaust gas recirculation valve (EGRV) 1a Step motor drive circuit 1b Step motor 1c Valve main body 11 … Power supply circuit 12… Input interface circuit
13 ... Decode circuit 14 ... Control circuit 15 ... Output stage circuit 16 ... Step holding determination circuit

Claims (5)

[Claims] 1. A control unit that generates control data for driving a step motor, and a drive unit that is configured separately from the control unit and that energizes the step motor according to the generated control data. In a control device for a step motor, which comprises a single communication line for transmitting control data generated by the control unit to the drive unit, the control unit drives the step motor in a forward direction, or
The drive unit is provided with a transmission unit that generates control data indicating whether to drive in the reverse direction or stops the rotation of the motor at predetermined time intervals and sends the control data to the communication line. Receiving means for receiving the control data, and energizing each phase of the step motor according to the control data received by the receiving means to rotate the step motor forward, reverse, or stop, and the step motor represented by the received control data. When the driving method of step motor is changed, the excitation pattern used for energizing each phase of the step motor is changed so that the rotation of the step motor is changed more slowly than the normal forward / reverse rotation. A step motor control device characterized by the above. 2. The energization control means sequentially determines the excitation phase to be energized based on the latest control data of the received control data and the control data immediately before the latest control data. The step motor control device according to claim 1. 3. A control unit that generates control data for driving the step motor, and a drive unit that is configured separately from the control unit and that energizes the step motor according to the generated control data. In a step motor control device including a single communication line for transmitting control data generated by the control unit to the drive unit, the control unit includes a step motor when it is necessary to rotate the step motor. Generate control data indicating whether to drive in the forward direction or in the reverse direction at predetermined time intervals,
A driving unit for transmitting to the communication line; the driving unit measures a time when the excitation phase of the step motor is fixed and a receiving unit for receiving the control data via the communication line, and from the measured time. Holding state determination means for determining the holding state of the step motor, and each time the receiving means receives the control data, the excitation phase of the step motor is sequentially switched according to the control data, and the step motor is rotated normally or reversely. At the same time, based on the determination result by the holding state determination means and the received control data, it is determined whether or not the driving method of the step motor is changed, and when the change of the driving method is determined, the normal time is An energization control unit that switches the excitation phase of the step motor with different excitation patterns and changes the rotation of the step motor more gently than during normal forward / reverse rotation. Controller of the step motor, characterized in that it includes. 4. The determining means measures the elapsed time after the control data is received by the receiving means,
4. The step motor control device according to claim 3, wherein a holding state of the step motor is determined when a predetermined time longer than a transmission cycle in which the transmission means transmits the control data is reached. 5. The energization control means sequentially switches excitation phases by two-phase excitation when driving the step motor forward or backward, and maintains rotation of the step motor by one-phase excitation when rotation of the step motor is stopped. When the driving method of the step motor is changed, immediately after that, the excitation method of the step motor is changed from two-phase excitation to one-phase excitation or from one-phase excitation to two-phase excitation. The control device for the step motor according to claim 4.