JPH1189295A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor which can suppress the heating of a motor without causing noise and minute vibration, in the holding condition of the rotational position of a rotor at stoppage of rotation. SOLUTION: Exciting coils 3a-3d for holding are larger in resistance value than exciting coils 2a-2d, and are connected in parallel to those exciting coils 2a-2d. Transistors Tr11-Tr14 are switched to supply some of the exciting coils 2a-2d and the exciting coils 3a-3d for holding with DC power B. A control circuit 5 controls the switching of the transistors Tr11-Tr14 so as to supply the exciting coils 3a-3d for holding with DC power B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly, to a stepping motor having a drive circuit for driving the rotor to stop rotating when the rotation is stopped.

[0002]

2. Description of the Related Art FIG. 7 shows a mechanical configuration of a PM (Permanent Magnet) type stepping motor 50. As shown in FIG. Inside the motor case 51, a pair of stator cores 52 and 53 formed in an annular shape are arranged. One stator core 5
2 accommodates first and third excitation coils 54a and 54c, and the other stator core 53 accommodates second and fourth excitation coils 54b and 54d. The first excitation coil 54a and the third excitation coil 54c are configured by winding their windings in opposite directions. The second exciting coil 54b and the fourth exciting coil 54d are configured by winding the windings in opposite directions. Then, a DC power source B described later is supplied to the first to fourth excitation coils 54 a to 54 d via a plurality of terminals 56 provided in the connector section 55.

[0003] A substantially cylindrical rotor 57 is disposed inside the stator cores 52 and 53. A rotor shaft 58 is fixed to the rotor 57, and the rotor shaft 58 is rotatably supported by a metal bearing (ball bearing) 59 and a slide bearing 60. The rotor 57 has a multi-pole magnetized magnet 61 on its outer periphery.

Next, FIG. 8 shows an electric configuration of a drive circuit 62 of the stepping motor 50. One end of each of the first to fourth excitation coils 54a to 54d of the motor 50 is connected to the DC power source B, and the other end is grounded via bipolar transistors (hereinafter simply referred to as transistors) Tr51 to Tr54. ing. The transistors Tr51 to Tr54 are on / off controlled based on control signals φ51 to φ54 from the control circuit 63, respectively.

The control circuit 63 receives an external rotation command signal S
1, control signals φ51 to φ54 corresponding to the rotation command signal S1 are output, and the transistors Tr51 to Tr51 are output.
r54 is sequentially turned on and off. Then, the first to fourth excitation coils 54a to 54d are sequentially excited, and the rotor 57
Rotates.

Here, when the rotation of the stepping motor 50 is stopped, the transistors Tr51 to Tr54 are turned off, and the first to fourth exciting coils 54a to 54d are in a non-excited state, so that the rotor 57 is in a free state. However, the rotor 57 in the free state rotates due to a load or the like driven by the stepping motor 50, and it is necessary to maintain the rotational position of the rotor 57 depending on the use application.

Therefore, while the rotation is stopped, the transistor Tr51
To Tr54 are turned on, and the exciting coil 54 is turned on.
There is a method in which a constant current is supplied to any of a to d to maintain the magnetized state. In this case, the rotor 57
It is attracted by the excited excitation coils 54a to 54d and its own rotational position is maintained.

However, in this method, while the rotation of the stepping motor 50 is stopped, the exciting coils 54a to 54d, to which a constant current is always supplied, generate heat, and the entire motor 50 is overheated. Was significantly impaired. Here, when the current flowing through the exciting coil is represented by “I” and the resistance of the exciting coil is represented by “R”, the heat generated by the motor is represented by the amount of heat generated by the exciting coil “I”.
² R ”. Therefore, reducing the current flowing through the exciting coil can greatly contribute to suppressing heat generation of the coil. Also, reducing the current flowing through the exciting coil is more effective than reducing the resistance value of the coil.

Therefore, conventionally, when the control circuit 63 receives a rotation stop signal S2 indicating the stop of the rotation of the stepping motor 50 from outside, the transistors Tr51 to Tr51 are turned off.
A control signal φ51 to φ54 having a duty ratio of, for example, 50% is output for any of r54, and the transistor Tr51
To Tr54 are chopper-controlled. Then, the exciting coil 54
Since any one of the coils 54a to 54d is excited, the rotational position of the rotor 57 is maintained, and the current flowing through the exciting coils 54a to 54d excited by the chopper control decreases. Will be reduced. Thus, conventionally, the motor 50
The whole was suppressed from becoming overheated.

[0010]

However, in the method in which the rotational position of the rotor 57 is held by chopper control, noise and minute vibration are generated by noise peculiar to chopper control.
Among them, the minute vibration is caused by the rotor shaft 58 and the dual bearing 59,
60, the shaft 5
There is a problem that deterioration of the bearing 8 and the double bearings 59 and 60 is accelerated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to generate heat of a motor without generating noise or micro-vibration in a state where a rotor rotational position is held when rotation is stopped. An object of the present invention is to provide a stepping motor capable of suppressing the occurrence of the stepping motor.

[0012]

According to a first aspect of the present invention, there is provided a rotor rotatably supported having a multi-polar magnetized magnet on an outer periphery thereof, and a rotatably supported rotor positioned at a position close to the outer periphery of the rotor. A plurality of exciting coils wound around the stator core provided, a stepping motor that sequentially excites each exciting coil based on a DC power supply supplied from the outside and rotates the rotor, wherein the A holding excitation coil having a large resistance value and connected in parallel to the excitation coil, switching means for switching to supply the DC power to one of the excitation coil and the holding excitation coil, and rotation of the rotor Control means for switching the switching means so as to supply DC power to the holding excitation coil so as to hold the rotational position of the rotor when stopped. It is the gist of.

According to a second aspect of the present invention, there is provided a rotor rotatably supported having a multi-pole magnetized magnet on the outer periphery, and a stator core provided at a position close to the outer periphery of the rotor. A plurality of excitation coils to be turned,
A stepping motor that sequentially excites each excitation coil based on a DC power supplied from the outside to rotate a rotor, the holding excitation coil being connected in series to the excitation coil, the excitation coil and the excitation coil. A switching unit for switching the supply of the DC power to one of the coil and the holding excitation coil; and a switching unit for holding the rotation position of the rotor when the rotation of the rotor is stopped. Control means for controlling the switching means so as to supply DC power thereto.

According to a third aspect of the present invention, the switching means comprises a transistor. The gist of the invention described in claim 4 is that the holding excitation coil is wound around at least one of the excitation coils at the same time.

According to the first and second aspects of the invention, when the rotational position of the rotor is held, the switching operation of the switching means increases the coil resistance value of the motor. Then, the current flowing through the coil when the rotor is held can be reduced. Therefore, heat generation from the coil when the rotor is held can be suppressed, and thus heat generation of the entire stepping motor can be suppressed. In addition, since heat generation can be suppressed without using chopper control, noise and fine vibration are not generated.

According to the third aspect of the present invention, since the switching means is constituted by a transistor, it can be easily constituted. According to the fourth aspect of the present invention, since the holding exciting coil is wound around at least one of the exciting coils at the same time, the assembling property of the motor is not greatly complicated.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. Note that the PM type stepping motor 1 of the present embodiment is characterized by a drive circuit that drives the motor 1. Therefore, hereinafter, for convenience of explanation, the description will focus on the drive circuit, and the same members as those of the conventional stepping motor 50 shown in FIG. 7 will be denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, one stator core 5
2 includes first and third excitation coils 2a and 2c,
And the third holding excitation coils 3a and 3c are accommodated. The first holding excitation coil 3a is wound around the core 52 at the same time as the first excitation coil 2a in the same direction, and the third holding excitation coil 3c is It is wound in the same direction as the exciting coil 2c. The first exciting coil 2a and the third exciting coil 2c are configured by winding their windings in opposite directions.

The other stator core 53 houses the second and fourth excitation coils 2b and 2d and the second and fourth holding excitation coils 3b and 3d. The second holding excitation coil 3b is connected to the core 53 by the second excitation coil 2b.
The fourth exciting coil 3d is wound around the core 53 in the same direction at the same time as the fourth exciting coil 2d. or,
The second excitation coil 2b and the fourth excitation coil 2d are configured by winding their windings in opposite directions.

First to fourth holding exciting coils 3a to 3d
Has a larger number of windings than the first to fourth excitation coils 2a to 2d, and each has a higher coil resistance value. The DC power source B is supplied to the first to fourth excitation coils 2a to 2d and the first to fourth holding excitation coils 3a to 3d via a plurality of terminals 56 provided in the connector unit 55. You.

Next, FIG. 2 shows an electric configuration of the drive circuit 4 of the stepping motor 1. The first to first motors 1
One end of each of the fourth excitation coils 2a to 2d is connected to the DC power supply B, and the other end is a bipolar transistor (hereinafter simply referred to as a transistor) Tr1 to Td.
Grounded via r4. Each transistor Tr1 to Tr4
Are controlled on and off based on control signals φ1 to φ4 from a control circuit 5 as control means.

The first to fourth holding exciting coils 3
a to 3d each have one end connected to the DC power supply B, and the other end each having a bipolar transistor (hereinafter simply referred to as a transistor) Tr11 to T as switching means.
Grounded via r14. Each transistor Tr11 to
Tr14 are control signals φ11 to φ11 from the control circuit 5, respectively.
On / off control is performed based on φ14.

The control circuit 5 receives a rotation command signal S1 from the outside.
Is input, control signals φ1 to φ4 corresponding to the rotation command signal S1 are output until the rotation stop signal S2 is input, and the transistors Tr1 to Tr4 are sequentially turned on and off. At this time, the transistors Tr11 to Tr14 are off. Then, the first to fourth excitation coils 2a to 2d are sequentially excited, and the rotor 57 rotates.

When the rotation stop signal S2 is input from the outside, the control circuit 5 outputs control signals φ11 to φ14 for any of the transistors Tr11 to Tr14 until the rotation command signal S1 is input. Transistor Tr11 ~
One of Tr14 is kept on. At this time,
The transistors Tr1 to Tr4 are turned off. Then, the excitation coil 3 is turned on by the turned-on transistors Tr11 to Tr14.
When any one of the rotors a to 3d is excited, the rotor 57 is attracted by the coils 3a to 3d to maintain its own rotational position.

In this way, the resistance values of the first to fourth holding exciting coils 3a to 3d are changed to the first to fourth exciting coils 2a to 3d.
Since the resistance is set to be higher than the resistance values of a to 2d, the current flowing through the holding excitation coils 3a to 3d can be suppressed to a small value. Therefore, the holding excitation coils 3a to 3a
The heat generation from 3d is suppressed, and the heat generation of the entire stepping motor 1 is suppressed.

Incidentally, the first to fourth holding excitation coils 3
Although it is conceivable to use a resistor in place of a to 3d, each of the holding excitation coils 3a to 3d can be wound simultaneously with the excitation coils 2a to 2b, so that assembly is easier than using a resistor.

As described above, this embodiment has the following features. (1) When the rotational position of the rotor 57 is held, the exciting coil 2
holding exciting coils 3a-3 having a higher resistance value than a-2d
A DC power supply B was supplied to d to maintain the rotational position of the rotor 57. Therefore, the holding excitation coils 3a to 3
Since d has a high resistance value, the current flowing through the coil when the rotor is held can be reduced. Therefore, heat generation from the coil when the rotor is held can be suppressed, and thus heat generation of the entire stepping motor 1 can be suppressed. In addition, since heat generation can be suppressed without using chopper control, noise and fine vibration are not generated.

(2) In addition, when the rotor is held, the switching of the DC power supply B to the holding excitation coils 3a to 3d is performed by the transistors Tr11 to Tr14. Therefore, the drive circuit 4 can be easily configured.

(3) The holding exciting coils 3a to 3d are wound simultaneously with the exciting coils 2a to 2d. Therefore,
The assembling of the stepping motor 1 is not greatly complicated.

The embodiment of the present invention is not limited to the above-described embodiment, and may be made as follows without departing from the spirit of the present invention. In the above embodiment, the first to fourth holding excitation coils 3
a to 3d are connected in parallel to the first to fourth excitation coils 2a to 2d, respectively, but the invention is not limited to this.
Alternatively, a holding excitation coil may be provided in parallel. The following configuration may be adopted.

For example, as shown in FIG. 3, the first to fourth holding exciting coils 3a to 3d may be connected in series to the first to fourth exciting coils 2a to 2d, respectively. In this case, one end of each of the transistors Tr1 to Tr4 is connected to a connection point between the exciting coils 2a to 2d and the holding exciting coils 3a to 3d, and the other end is grounded. Then, when rotating the rotor 57, the control circuit 5 sequentially turns on the transistors Tr1 to Tr4 by the control signals φ1 to φ4, as described above. When the rotational position of the rotor 57 is held, the control circuit 5 holds any of the transistors Tr11 to Tr14 in an on state by the control signals φ11 to φ14. In the holding state, the resistance value of the exciting coils 3a to 3d is added to the resistance value of the exciting coils 2a to 2d, so that the current flowing through the coils can be suppressed to a small value. Therefore, heat generation from the coil is suppressed. Each of the holding excitation coils 3a to 3d includes first to fourth excitation coils 2a to 2d.
The coil resistance does not always have to be higher than d.

As shown in FIG. 4, a bipolar transistor (hereinafter simply referred to as "transistor") Tr21 is interposed between the first to fourth excitation coils 2a to 2d and the power supply B. A bipolar transistor (hereinafter, referred to as a series-connected transistor)
Tr22 and the holding excitation coil 3e may be interposed. These transistors Tr21, T
r22 is turned on / off by control signals φ21 and φ22 from the control circuit 5. When rotating the rotor 57, the control circuit 5 uses the control signal φ21 to control the transistor Tr2.
1 is turned on, and the transistor T is controlled by control signals φ1 to φ4.
r1 to Tr4 are sequentially turned on. When the rotational position of the rotor 57 is held, the control circuit 5 turns on the transistor Tr22 with the control signal φ22, and holds one of the transistors Tr1 to Tr4 with the control signals φ1 to φ4. In the holding state, the resistance value of the holding excitation coil 3e is added to the resistance values of the excitation coils 2a to 2d, so that the current flowing through the coils can be suppressed to a small value. Therefore, heat generation from the coil is suppressed.

As shown in FIG. 5, the same operation can be performed even if the transistor Tr22 is omitted from the drive circuit 4 shown in FIG. 4, and the current flowing through the coil can be reduced. Therefore, heat generation from the coil is suppressed.

As shown in FIG. 6, since the first and third excitation coils 2a and 2c are wound in opposite directions, one excitation coil 2ac is connected to the transistor T.
The direction of current flow may be reversed at r1 and Tr3. Similarly, the second and fourth excitation coils 2
b and 2d are wound in opposite directions, so that one exciting coil 2bd is connected to the transistors Tr2 and Tr4.
To reverse the direction of current flow. Even in this case, the rotor 57 can rotate in the same manner as described above. One end of the exciting coil 2ac is connected to the power source B via the holding exciting coil 3e and the transistor Tr23a, and is grounded via the holding exciting coil 3e and the transistor Tr23c. Exciting coil 2b
One end of the holding excitation coil 3e and the transistor T
Connected to the power supply B via r23b, and grounded via the holding excitation coil 3e and the transistor Tr23d. When the rotational position of the rotor 57 is held,
The control circuit 5 turns on any of the transistors Tr23a to Tr23d with the control signals φ23a to φ23d, and holds the transistors Tr1 to Tr4 connected in series to the transistors Tr23a to Tr23d, respectively. The transistors Tr23a and Tr23c and the transistors Tr23b and Tr23d are not turned on at the same time. And in this holding state,
Since the resistance of the holding excitation coil 3e is added to the resistance of the excited excitation coils 2ac and 2bd, the current flowing through the coil can be suppressed to a small value. Therefore, heat generation from the coil is suppressed.

In the above embodiment, the drive circuit 4 of the stepping motor 1 is constituted by four exciting coils 2a to 2d, but the number of exciting coils is not limited to this. In the above embodiment, the first to fourth holding excitation coils 3
In a to 3d, the number of windings is increased for the first to fourth excitation coils 2a to 2d in order to increase the coil resistance value. However, the present invention is not limited to this. For example, the holding excitation coil 3a
To 3d may be constituted by thin lines.

In the above embodiment, the bipolar transistors Tr1 to Tr4 are used, but other switching elements may be used. In the above-described embodiment, the switching is performed using the bipolar transistors Tr11 to Tr14, Tr21, and Tr22 in order to supply power to the holding excitation coil when the rotation position of the rotor 57 is held. The switching may be performed by using the above switch circuit.

[0037]

As described in detail above, according to the present invention,
It is possible to provide a stepping motor capable of suppressing the heat generation of the motor without generating noise or minute vibration in a state where the rotor rotational position is held when the rotation is stopped.

[Brief description of the drawings]

FIG. 1 is a mechanical configuration diagram of a stepping motor according to an embodiment.

FIG. 2 is an electrical configuration diagram of the same stepping motor.

FIG. 3 is an electrical configuration diagram of another example of a stepping motor.

FIG. 4 is an electrical configuration diagram of another example of a stepping motor.

FIG. 5 is an electrical configuration diagram of another example of a stepping motor.

FIG. 6 is an electrical configuration diagram of another example of a stepping motor.

FIG. 7 is a mechanical configuration diagram of a conventional stepping motor.

FIG. 8 is an electrical configuration diagram of the same stepping motor.

[Explanation of Symbols] 2a to 2d: exciting coil, 3a to 3d: holding exciting coil, 5: control circuit as control means, 52, 53: stator core, 57: rotor, 61: magnet, B: DC power supply, Tr11 .About.Tr14... Transistors as switching means.

Claims (4)

[Claims] 1. A multi-pole magnetized magnet (6) on the outer periphery.
1) and a rotatably supported rotor (57), and a plurality of excitation coils (5) wound around a stator core (52, 53) provided at a position close to the outer periphery of the rotor (57). 2a to 2d), wherein the excitation coils (2a to 2d) are sequentially excited based on a DC power supply (B) supplied from the outside to rotate the rotor (57), and the stepping motor includes: (2a to 2d) having a higher resistance value, holding excitation coils (3a to 3d) connected in parallel to the excitation coils (2a to 2d), the excitation coils (2a to 2d) and the holding coil. Switching means (Tr11 to Tr14) for switching to supply the DC power supply (B) to one of the exciting coils (3a to 3d); and when the rotation of the rotor (57) is stopped, the rotation of the rotor (57) is stopped.
In order to maintain the rotational position of the holding excitation coil (3a
A stepping motor for controlling the switching of the switching means (Tr11 to Tr14) so as to supply a DC power supply (B) to the stepping motor. 2. A multi-pole magnetized magnet (6) on the outer periphery.
1) and a rotatably supported rotor (57), and a plurality of excitation coils (5) wound around a stator core (52, 53) provided at a position close to the outer periphery of the rotor (57). 2a to 2d), wherein the excitation coils (2a to 2d) are sequentially excited based on a DC power supply (B) supplied from the outside to rotate the rotor (57), and the stepping motor includes: (2a to 2d) and holding exciting coils (3a to 3d and the like) connected in series to the exciting coils (2a to 2d) and the exciting coils (2a to 2d).
2d) and switching means (Tr11 to Tr14, etc.) for switching to supply the DC power supply (B) to one of the holding exciting coils (3a to 3d, etc.), and when the rotor (57) stops rotating. The rotor (57)
In order to maintain the rotational position of the excitation coils (2a to 2a).
d) and the switching means (Tr1
(1 to Tr14, etc.). 3. The switching means includes a transistor (Tr11).
3. The stepping motor according to claim 1, wherein the stepping motor comprises: 4. The holding excitation coil (3a to 3d, etc.)
Is wound around at least one of the exciting coils (2a to 2d) at the same time.
3. The stepping motor according to any one of 3.