JP2001359298A - Stepping motor with temperature storage function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate reduction in cost, size and power consumption through reduction in number of parts by eliminating a space heater from a device utilizing a stepping motor, such as an electronic valve to be used in the cold region for the protection with heating under the electronic control. SOLUTION: The surface temperature of the stepping motor is detected by mounting a temperature sensor thereto. When detected temperature of this temperature sensor becomes equal to the prescribed temperature (for example, 0 deg.C or lower), a non-drive heating current which will not give changes to the rotating angle of the motor is supplied, under the control of power feeding condition to a drive coil. Thereby, since the drive coil generates heat due to Joule heating, under the condition that the stepping motor be in a stationary state, protection from heating of device can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is suitable for controlling the opening / closing and positioning of valves used in cold regions, etc.
The present invention relates to a stepping motor having a heat retaining function.

[0002]

2. Description of the Related Art Conventionally, a stepping motor has been used to control the opening / closing and positioning of a valve. FIG. 12 is a partially broken side sectional view showing a main part of an electronic valve using a stepping motor. An electronic valve does not require an air source as compared with a pneumatic valve, so that maintenance costs can be reduced and the cost of the system can be significantly reduced. In FIG. 12, 1 is a stepping motor, 2 is a circuit board on which an electronic circuit for driving the stepping motor 1 is built, 3 is a stepping motor 1 and a circuit board 2
Cover.

[0003] The electronic valve 100 is used for various purposes, and its use environment is various. For example, it may be used in an environment where the ambient temperature is 0 ° C. or less. In this case, the stepping motor 1 may freeze and stop operating. Therefore, conventionally, a space heater 4 is provided inside the cover 3 to electrically freeze the internal space to prevent the stepping motor 1 from freezing. The space heater 4 is always energized or turned on / off by a thermostat.

[0004]

However, according to such an electronic valve 100, the provision of the space heater 4 inside the cover 3 increases the number of parts and increases the cost. In addition, a space for installing the space heater 4 must be ensured inside the cover 3, so that downsizing cannot be promoted. Space heater 4
The power consumption is large because rough temperature control is performed such that power is constantly supplied or turned on / off by a thermostat. Further, the cover 3 is provided by the space heater 4.
Since the internal space is heated to apply heat to the stepping motor 1 from the outside, the heating efficiency is poor.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to eliminate a space heater from a device using a stepping motor such as an electronic valve used in a cold region, etc. Heat protection by control reduces the number of parts and promotes cost reduction and miniaturization.Also, accurate temperature control and heat retention function that increases heating efficiency and reduces power consumption To provide a stepping motor.

[0006]

According to a first aspect of the present invention, there is provided a temperature sensor for detecting an ambient temperature of a stepping motor. When the stepping motor is at a predetermined temperature or lower and all the drive coils are in a non-energized state and the stepping motor is in a stationary state, a non-drive heating current that does not change the rotation angle of the stepping motor is supplied to the stepping motor. It was made. According to the present invention, the temperature detected by the temperature sensor is a predetermined temperature (for example, 0 ° C.)
When the following conditions are satisfied, the drive coils of the stepping motor in a stationary state with all of the drive coils in a non-energized state,
A non-driving heating current that does not change the rotation angle of the motor is supplied. As a result, the drive coil generates heat due to Joule heat while the stepping motor remains stationary. If the motor is rotating, it waits for the motor to stop and then enters the heating operation (the motor generates heat while the motor is rotating, so it is not necessary to energize for heating).

[0007] The invention according to claim 2 (second invention) is the first invention.
In the present invention, when the temperature detected by the temperature sensor becomes equal to or higher than a predetermined overheat protection temperature, power supply to the stepping motor is regulated even when the motor is rotating. According to the present invention, the temperature detected by the temperature sensor is set to a predetermined overheat protection temperature (for example, 100 ° C.).
Then, the power supply to the stepping motor is stopped or limited.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 2 is a block diagram showing a main part of an electronic valve using a stepping motor with a heat retaining function according to the present invention. In the figure, 1 is a stepping motor, 5 is a gear mechanism connected to a rotating shaft of the stepping motor 1, 6 is an output shaft mechanically connected to a valve body, 7 is a temperature sensor attached to the stepping motor 1, Reference numeral 8 denotes a positioning control unit, 9 denotes a motor driver, 10 denotes a DC power supply, 11 denotes a temperature detection / processing unit, and 12 denotes a position detection unit that detects the rotation angle position of the output shaft 6.

Generally, a stepping motor has two or more drive coils. FIG. 3 shows the principle of a bipolar stepping motor. In FIG. 3, 1-1,
1-2 is a drive coil, and the drive coils 1-1 and 1-2
The rotor 1-3 is rotated one step at a time by changing the direction of the current flowing through the rotor in a predetermined order. For simplicity of description, the stepping motor 1 in the present embodiment is this type of stepping motor.

FIG. 4 shows the relationship between the excitation phase and the coil polarity when the stepping motor 1 is rotated by the two-phase excitation method. Are excitation phases, A and B are one end and the other end of the drive coil 1-1, C and D are drive coils 1
2 shows one end and the other end. In the excitation phase, the polarity of A of the drive coil 1-1 is “+”, the polarity of B is “−”, the polarity of C of the drive coil 1-2 is “+”, and the polarity of D is “−”.
And In the excitation phase, the polarity of A of the drive coil 1-1 is “+”, the polarity of B is “−”, the polarity of C of the drive coil 1-2 is “−”, and the polarity of D is “+”. In the excitation phase, the polarity of A of the drive coil 1-1 is "-", the polarity of B is "+", the polarity of C of the drive coil 1-2 is "-", and the polarity of D is "+". In the excitation phase, the drive coil 1-1
The polarity of A is "-", the polarity of B is "+", and the driving coil 1
The polarity of C of -2 is "+", and the polarity of D is "-".

The rotation direction of the stepping motor 1 is controlled in the order of switching the coil polarity. The rotation speed is controlled by the switching speed of the coil polarity. When rotating forward, ,,,
To reverse the rotation, the polarity of the coil is switched in the order of, for example,.

When the stepping motor 1 is rotated forward,
Paying attention to the polarities of A and C, a time chart as shown in FIG. 5 is obtained. When the stepping motor 1 is rotated in reverse, paying attention to the polarities of A and C, a time chart as shown in FIG. 6 is obtained.

Here, the current to the exciting coil 1-1 is represented by I
Assuming that the current to the exciting coil 1-2 is I2, the currents I1 and I2 as shown in FIG.
Flow to 1 and 1-2. I1 has a phase 90 more than I2.
。I'm late. At the time of reverse rotation, the currents I1,
I2 flows to the exciting coils 1-1 and 1-2. I1 is 90 ° ahead of I2 in phase. During the stop, the currents I1 and I2 to the exciting coils 1-1 and 1-2 are cut off, and a non-energized state is set. When the currents I1 and I2 to the excitation coils 1-1 and 1-2 are cut off, the stepping motor 1 stops at the magnetically stable point at that time. It shows a strong reaction force against external force that is going to deviate from the stable point.

FIG. 9 shows rotation (forward rotation, reverse rotation) and stop (stationary).
Shows an example in which currents I1 and I2 are supplied to excitation coils 1-1 and 1-2 in a case where is repeated. In this example, the period T
1, “reverse rotation”, “stationary” during period T2, “normal rotation” during period T3, “stationary” during period T4, and “reverse rotation” during period T5. As can be seen from this figure, normally, in the “stationary” state, the excitation coil 1-1
And the current to 1-2 is cut off, and a non-energized state is set.

In the present embodiment, the temperature sensor 7 is attached to the stepping motor 1 which operates according to such a basic principle. The temperature sensor 7 detects the surface temperature of the stepping motor 1 as the ambient temperature. Further, a temperature detection / processing section 11 is provided so as to give a temperature detected by the temperature sensor 7. Temperature detection / processing unit 11
Sends a heating command to the positioning control unit 8 when the temperature detected by the temperature sensor 7 becomes 0 ° C. or less.

FIG. 1 shows an exciting coil 1-1 when a heating command is sent from the temperature detecting / processing unit 11 to the positioning control unit 8.
2 shows an example of supplying currents I1 and I2 to power supply lines 1-2 and 1-2. In this supply example, the heating operation starts at a point t0 in the period T4.

In a period T1, the positioning control unit 8 calculates a deviation between the setting input from the host device and the detection input from the position detecting unit 12, generates a positioning control signal that makes this deviation zero, and generates a motor driver. Send to 9. The motor driver 9 receives the positioning control signal from the positioning control unit 8 and sends to the DC power supply 10 pulse signals S1 and S2 having a phase shift of 90 ° and a duty ratio of 50%.

The motor driver 9 generates pulse signals S1 and S2
Is always generated. The pulse signal S1 is the pulse signal S2
The phase is advanced by 90 °. In the period T1, the output terminals 9-1 and 9 are set to rotate the stepping motor 1 in the reverse direction.
-2 to output pulse signals S1 and S2. In response to the pulse signals S1 and S2, a current I1 having the same phase and the same waveform as the pulse signal S1 is supplied from the DC power supply 10 to the exciting coil 1-1, and the current I2 having the same phase and the same waveform as the pulse signal S2 is provided.
Is supplied to the excitation coil 1-2. Thus,
,..., The coil polarity is switched in this order, and the stepping motor 1 rotates in the reverse direction.

In the period T2, the positioning control unit 8 confirms that the deviation between the setting input from the host device and the detection input from the position detecting unit 12 is zero, and the motor driver 9
Send stop command to Thereby, the motor driver 9
The transmission of the pulse signals S1 and S2 to the DC power supply 10 is interrupted, and the current I from the DC power supply 10 to the stepping motor 1 is interrupted.
1, I2 is cut off. Thereby, the stepping motor 1 stops at the magnetically stable point at that time.

In the period T3, the positioning control unit 8 calculates a deviation between the setting input from the host device and the detection input from the position detecting unit 12, generates a positioning control signal that makes this deviation zero, and generates a motor driver. Send to 9. The motor driver 9 receives the positioning control signal from the positioning control unit 8 and sends the pulse signals S1 and S2 to the DC power supply 10.
In the period T3, the output mode is switched to rotate the stepping motor 1 forward, and the output terminals 9-1 and 9-2 are switched.
Output pulse signals S2 and S1. Receiving these pulse signals S2 and S1, pulse signal S2 is supplied from DC power supply 10.
The current I1 having the same phase and the same waveform is supplied to the exciting coil 1-1, and the current I2 having the same phase and the same waveform as the pulse signal S1 is supplied to the exciting coil 1-2. As a result,
, The coil polarity is switched in this order, and the stepping motor 1 rotates forward.

In the period T4, the positioning control unit 8 confirms that the deviation between the setting input from the host device and the detection input from the position detecting unit 12 has become zero, and
Send stop command to Thereby, the motor driver 9
The transmission of the pulse signals S1 and S2 to the DC power supply 10 is interrupted, and the current I from the DC power supply 10 to the stepping motor 1 is interrupted.
1, I2 is cut off. Thereby, the stepping motor 1 stops at the magnetically stable point at that time.

In FIG. 1, the heating operation starts at a point t0 in the period T4. The temperature detection / processing unit 11 includes a temperature sensor 7
, The ambient temperature (surface temperature) of the stepping motor 1 is monitored. When the surface temperature of the stepping motor 1 becomes 0 ° C. or less, the temperature detection / processing unit 11 sends a heating command to the positioning control unit 8.

In response to the heating command, the positioning controller 8
In the stationary state of the stepping motor 1, that is, when the currents I1 and I2 to the exciting coils 1-1 and 1-2 are cut off, the pulse signals S1 and S2 constantly generated in the motor driver 9 And the latched signals S1 'and S2' are applied to the DC power supply 10. At time t0 in FIG. 1, when the pulse signal S1 is at the "H" level and the pulse signal S2 is at the "L" level, the level is latched, and the "H" level signal S1 'is supplied to the DC terminal via the output terminal 9-1. The signal S2 'at the "L" level is supplied to the DC power supply 10 via the output terminal 9-2. As a result, the current I1 in the AB direction flows to the drive coil 1-1 of the stepping motor 1, and the current I2 in the DC direction flows to the drive coil 1-2.

Thus, while the stepping motor 1 remains stationary, the drive coils 1-1 and 1-2 generate heat due to Joule heat, that is, the drive coils 1-1 and 1-2.
The currents I1 and I2 are supplied as non-driving heating currents, and the heating operation starts. Note that the rotation angle of the stepping motor 1 may change by one step depending on the relationship between the excitation phase when the stepping motor 1 finally stops and the excitation phase when the heating operation starts. However, even if it rotates one step, that is, if the rotation axis of the stepping motor 1 is 1
Even in the step rotation, the gear is down-shifted via the gear mechanism 5 and the rotational force is transmitted to the output shaft 6, so that the change in the rotation angle of the output shaft 6 is very small and causes no problem. After the one-step rotation, the rotation angle of the stepping motor 1 does not change while the non-drive heating current is being supplied.

In the period T5, the positioning control unit 8 calculates a deviation between the setting input from the host device and the detection input from the position detecting unit 12, generates a positioning control signal that makes this deviation zero, and generates a motor driver. Send to 9. in this case,
The positioning control unit 8 first performs a heating operation in response to a heating command from the temperature detection / processing unit 11, but gives priority to rotation control based on a positioning control signal. That is, since the motor generates heat while the motor is rotating, it is determined that energization for heating is unnecessary, and the heating operation is interrupted, and rotation control based on the positioning control signal is performed.

Although not shown in the time chart of FIG. 1, while the stepping motor 1 is rotating, the temperature sensor 7
Even if the detected temperature becomes 0 ° C. or lower, it is determined that the energization for heating is unnecessary. In this case, the heating operation is started after the rotation of the stepping motor 1 is stopped.
During the heating operation, if the temperature detected by the temperature sensor 7 exceeds a certain level (for example, 20 ° C. or higher), the temperature detection /
The processing unit 11 sends a heating stop command to the positioning control unit 8,
As a result, the supply of the non-driving heating current to the drive coils 1-1 and 1-2 is interrupted, and the heating operation is stopped.

In FIG. 1, the levels of the pulse signals S1 and S2 when the heating command is issued are latched, and the latched signals S1 'and S2' are applied to the DC power supply 10, but the pulse signal S1 May be latched and applied to the DC power supply 10. That is, as shown in FIG. 10, without supplying current to the drive coil 1-2,
A non-drive heating current may be supplied only to the drive coil 1-1 side. Of course, the reverse, that is, the non-driving heating current may be supplied only to the driving coil 1-2 side without supplying the current to the driving coil 1-1.

Further, only the pulse signal S1 (or S2) may be supplied to the DC power supply 10. That is, as shown in FIG. 11, current is not supplied to the drive coil 1-2 (or 2-1), and the drive coil 1-1 (or 1-2) is not supplied.
A pulsed non-driving heating current having a duty ratio of 50% may be supplied only to the side. Actually, when the detection temperature is set to 0 ° C., the voltage to the drive coil during heating is set to 24 V, the current is set to about 2 A, and the duty ratio is set to about 50%, the motor surface becomes −5 ° C. Heat to approximately 10 ° C.

In the case of the non-driving heating current supply method as shown in FIGS. 10 and 11, regardless of the excitation phase when the stepping motor 1 is stopped immediately before, the stepping motor is started at the start time t0 of the heating operation. No force for rotating the motor 1 is generated, and the rotation angle of the stepping motor 1 does not change by one step. That is, the drive coils 1-1 and 1-2 generate heat due to Joule heat in a state where the rotation angle of the stepping motor 1 does not change and remains stopped.

In the present embodiment, the temperature sensor 7 is attached to the stepping motor 1, and the surface temperature is detected as the ambient temperature of the stepping motor 1.
The temperature of the internal space remote from the stepping motor 1 may be detected. In the present embodiment, the stepping motor 1 has two drive coils. However, the present invention can be similarly applied to a stepping motor having two or more drive coils.

Further, an overheat protection function may be added to the temperature detection / processing section 11. That is, the overheat protection temperature is previously set to, for example, 100 ° C., and when the temperature detected by the temperature sensor 7 exceeds the overheat protection temperature, the temperature detection / processing unit 11 controls the positioning control unit even if the motor is rotating. 8, the supply of the currents I1 and I2 to the drive coils 1-1 and 1-2 of the stepping motor 1 may be cut off or limited. Accordingly, it is possible to avoid a failure such as burning of the drive coils 1-1 and 1-2.

[0032]

As is apparent from the above description, according to the present invention, when the temperature detected by the temperature sensor falls below a predetermined temperature, all of the drive coils are de-energized and the stationary stepping motor is driven. A non-drive heating current that does not change the rotation angle of the motor is supplied to the coil (first invention), and the drive coil generates heat by Joule heat while the stepping motor is stationary. As a result, space heaters can be eliminated from equipment that uses a stepping motor such as an electronic valve, and the number of parts can be reduced to promote cost reduction and miniaturization. In addition, accurate temperature control and heating efficiency can be increased to reduce power consumption. Can be reduced. Further, when the temperature detected by the temperature sensor is equal to or higher than the predetermined overheat protection temperature (second invention), the power supply to the stepping motor is stopped or limited, and failure such as burning of the drive coil can be avoided. become able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of supplying a non-driving heating current to a stepping motor when a heating command is sent from a temperature detection / processing unit to a positioning control unit.

FIG. 2 is a block diagram showing a main part of an electronic valve using a stepping motor with a heat retention function according to the present invention.

FIG. 3 is a principle diagram of a bipolar type stepping motor.

FIG. 4 is a diagram showing a relationship between an excitation phase and a coil polarity when the stepping motor is rotated by a two-phase excitation method.

FIG. 5 is a time chart paying attention to the polarities of A and C of the drive coil when the stepping motor is rotated forward.

FIG. 6 is a time chart paying attention to the polarities of A and C of the drive coil when the stepping motor is rotated in the reverse direction.

FIG. 7 is a diagram showing excitation currents I1 and I2 supplied to the stepping motor during forward rotation.

FIG. 8 is a diagram showing excitation currents I1 and I2 supplied to the stepping motor at the time of reverse rotation.

FIG. 9 is a diagram illustrating an example of supplying currents I1 and I2 to the stepping motor when rotation (forward rotation, reverse rotation) and stop (stationary) are repeated.

FIG. 10 is a diagram illustrating another example of supplying a non-driving heating current to the stepping motor when a heating command is sent from the temperature detection / processing unit to the positioning control unit.

FIG. 11 is a diagram illustrating another example of supplying a non-driving heating current to a stepping motor when a heating command is sent from a temperature detection / processing unit to a positioning control unit.

FIG. 12 is a partially broken side sectional view showing a main part of an electronic valve using a stepping motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stepping motor, 1-1, 1-2 ... Drive coil, 1-3 ... Rotor, 2 ... Circuit board, 3 ... Cover, 5 ...
Gear mechanism, 6 output shaft, 7 temperature sensor, 8 positioning controller, 9 motor driver, 10 DC power supply, 11
Temperature detection / processing unit, 100: electronic valve.

Claims (2)

[Claims] A stepping motor having first to Nth (N ≧ 2) driving coils; a temperature sensor for detecting an ambient temperature of the stepping motor; and a temperature detected by the temperature sensor being equal to or lower than a predetermined temperature. And a non-driving heating current supply for supplying a non-driving heating current that does not change the rotation angle of the stepping motor to a driving coil of the stepping motor when all of the driving coils are in a non-energized state and the stepping motor is in a stationary state. And a stepping motor having a heat retaining function. 2. A power supply restricting means according to claim 1, further comprising a power supply restricting means for restricting power supply to said stepping motor when a temperature detected by said temperature sensor is equal to or higher than a predetermined overheat protection temperature. Stepping motor with heat retention function.