JPH10178770A - Both permanent magnet-type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor such as a stepping motor, in which detent torque is produced and thus power is not consumed, and the stop position accuracy is high, miniaturization is feasible, and the stop position is controllable. SOLUTION: In this motor, permanent magnets are installed on a fixed-side cylinder 4 and the rotor installed on a rotary shaft 5, and detent torque at the time of non-energization originates by the attractive force among the permanent magnets permanent magnets 1-1 and 2-1 in the figure. The initiation of rotation is accomplished using electromagnets 3-1 to 3-6 placed between the permanent magnets. The electromagnets are excited, so that rotation is generated for a period starting from when the rotor is in a stop state in which the permanent magnets come closest to one another to when the rotor comes to the intermediate point between the stop state and the subsequent stop state, and thereafter driven to the subsequent stop position by the permanent magnets. The number of permanent magnets installed on the cylinder 4 side and the number of permanent magnets installed on the rotor side are set so that the numbers re relatively prime with each other and are two or above. Thereby exercising stop control at an angle smaller than the angle formed by the nine adjoining permanent magnets using both the permanent magnets is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor, and more particularly, to a motor, which requires a large detent torque such as a camcorder. The present invention relates to a motor stop position control that can be applied to a stepping motor or the like in which the number of magnets that can be arranged is limited.

[0002]

2. Description of the Related Art FIG. 4 is a diagram schematically showing the structure of a conventional example of a permanent magnet type stepping motor. In FIG. 4, reference numeral 4 'denotes a fixed cylinder, 3'-1, 3'-2,
Reference numerals 3'-3 and 3'-4 denote electromagnets arranged on the fixed cylinder 4 ', 5' denotes a rotating shaft, and 2 'denotes a rotating permanent magnet fixed to the rotating shaft 5'. In the conventional permanent magnet type stepping motor, the detent torque generated at the time of non-energization is made by the attraction force between the electromagnet of the cylinder and the permanent magnet of the rotor. However, the force is not so strong, and for example, when used in a motor for driving a lens of a camcorder, it is not enough to fix the position of the lens at a fixed position. Therefore, conventionally, even when the rotation of the motor is stopped, a braking current is supplied to the electromagnet, and a braking force is obtained by maintaining the excitation state.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. H04-42766, a stepping motor that generates a large detent torque by using a permanent magnet for both a cylinder and a rotor has been proposed. FIG. 5 shows a conventional example of a double permanent magnet type stepping motor using permanent magnets for both a cylinder and a rotor. In FIG.
4 'is a fixed cylinder, 1'-1, 1'-2, 1'-
Reference numerals 3 and 1'-4 denote electromagnets arranged on the fixed cylinder 4 ', 5' denotes a rotating shaft, 2 'denotes a rotor permanent magnet fixed to the rotating shaft 5', 3'-1, 3'-2. , 3'-3 and 3'-
4 is a permanent magnet fixed to the cylinder. However, this type of stepping motor has a drawback that the minimum controllable rotation angle becomes large when used in a small motor due to its complicated structure. Specifically, in the case of the stepping motor shown in FIG. 5, while the magnets on the cylinder side are arranged at every 45 degrees with respect to the rotation center, the stop position accuracy is 90 degrees and the stop position control with high accuracy is performed. It can be seen that the configuration is not possible. For example, when this is used for a focus motor of a camcorder, this directly affects the focus accuracy, restricts the performance of the camera itself, and causes a performance problem.

[0004]

As described above, in the conventional method, power is always consumed regardless of whether the motor is driven or not, which is inconvenient for equipment requiring power saving. A stepping motor that generates a large detent torque by using permanent magnets for both a cylinder and a rotor disclosed in Japanese Patent Application Laid-Open No. 4-042766 has a complicated structure. There was a problem that the minimum possible rotation angle became large and the stop position accuracy became poor. The present invention has been made in view of such problems in the prior art, and does not consume power to generate detent torque, has a good stop position accuracy, and can be downsized as a motor. The problem to be solved is to provide the motor capable of controlling the motor.

[0005]

According to the first aspect of the present invention, permanent magnets are arranged at equal intervals along the rotation direction on the stator side and the rotor side, and an attractive force can be applied to the magnets on both sides. In the two permanent magnet type motors that are arranged, the numbers of the permanent magnets on the stator side and the rotor side are relatively prime, and
It is characterized in that each side is set to be two or more.

According to a second aspect of the present invention, in the first aspect, the stator and the rotor are changed from one ground state caused by the action of an attractive force acting between the pair of permanent magnets on the stator side and the rotor side. An electromagnet capable of excitation control for generating an attractive force and / or a repulsive force between the permanent magnet and the permanent magnet is provided so that the mutual relation reaches the ground state of the next cycle through the transition state. Is what you do.

According to a third aspect of the present invention, in the second aspect of the present invention, the electromagnet capable of controlling the excitation is provided on either the stator side or the rotor side. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a main part of an embodiment of a stepping motor according to the present invention, showing the motor in a ground state. In FIG. 1, 4 is a cylindrical cylinder of a motor, 5 is a rotating shaft, 1-
1, 1-2 and 1-3 are permanent magnets fixed to the inner surface of the cylinder 4 of the motor, 2-1, 2-2, 2-3 and 2-
4 is a permanent magnet fixed to the rotating shaft 5;
2,3-3,3-4,3-5 and 3-6 are cylinder 4
An electromagnet fixed to the inner surface of the. Here, each magnet provided on the inner surface of the cylinder 4 is (1-1)-(3-
1)-(3-2)-(1-2)-(3-3)-(3-
4) In the order of-(1-3)-(3-5)-(3-6),
They are arranged at equal intervals (every 40 degrees).

The operation of the above configuration will be described below. In the state of FIG. 1, the permanent magnet 1-1 on the cylinder side and the permanent magnet 2-1 on the rotor side are close to each other, and generate a braking force.
In a stopped state. This state is the first ground state. Next, the motor rotates clockwise by one step, and transitions to the second ground state in which the permanent magnets 1-2 and 2-2 are closest (rotates by 30 degrees). explain. First, the electromagnets 3-1, 3-2, 3-3, 3-4
As long as 3-5 and 3-6 are not energized, the motor will try to stay in the first ground state. Next, the electromagnet 3-1 and the electromagnet 3
-4 is energized to attract the permanent magnets 2-1 and 2-3. Thereby, the rotating shaft 5 is rotated by 15 degrees or more, and the transition state is exceeded. Then, since the permanent magnets 1-2 and 2-2 are closer to each other than the permanent magnets 1-1 and 2-1, the motor naturally transitions to the second ground state. Thus, one step rotation of the stepping motor is completed.

This type of stepping motor is disclosed in
Japanese Patent Application Laid-Open No. -042766 proposes, but the stepping motor shown in this conventional example has a complicated structure,
When used in small motors used in portable electronic devices such as video cameras, the minimum controllable rotation angle increases,
There was a problem that control accuracy deteriorated. However, FIG.
As described in the embodiment described above, the control accuracy can be improved by setting the number of permanent magnets disposed on the cylinder side and the rotor side to be relatively prime and each side to be two or more. In FIG. 1, nine magnets are arranged on the cylinder side, and the angle between adjacent magnets is 40 degrees. In addition, three permanent magnets out of the nine magnets on the cylinder side are arranged, whereas four permanent magnets are arranged on the rotor side. Since the numbers 3 and 4 of the permanent magnets on both sides are relatively prime and each is a number of 2 or more, the minimum control angle in rotation in this case is:
30 degrees, which is smaller than 40 degrees.

In the conventional stepping motor, as shown in FIG. 5, eight magnets on the cylinder side are arranged at every 45 degrees with respect to the center of rotation, whereas the number of permanent magnets on both sides is two. And 4, the stop position accuracy is 90 degrees, which indicates that the stop position control with high accuracy has not been performed. This is unfavorable, for example, when it is used for a focus motor of a camcorder because it directly affects the focus accuracy and limits the performance of the camera itself. As in the above embodiment of the present invention, by setting the numbers of magnets disposed on the cylinder side and the rotor side to be relatively prime, and by setting each side to be two or more, a high-precision stop position accuracy can be obtained. In the required stepping motor, it is possible to solve the contradiction of the deterioration of the stop position accuracy due to the limitation of the number of magnets that can be arranged for downsizing.

The rotation and stop operations of the motor configured as described above will be described more specifically and in detail with reference to FIG. FIG. 2 is a chart for explaining transition of the operation state of the stepping motor according to the embodiment of the present invention. In FIG. 2, the vertical axis represents time from top to bottom, and the horizontal axis represents an angle taken clockwise about the rotation axis 5 with the upward direction in FIG. The symbols ○ represent 0 °, 90 °, 180 ° and 270 ° at time 0.
Each permanent magnet (2-1) fixed to the rotor at an angle of
(2-2), (2-3) and (2-4) are shown, and the arrows connecting them represent position changes due to rotation of the permanent magnet with time. Also, on the angle of the horizontal axis, (permanent magnet) and (electromagnet) (marked with →) at each angular position of the cylinder surface on the fixed side are shown, and the thick line indicates the interaction due to excitation of the electromagnet Represents a magnet, and the wavy lines indicate the connection with the interacting partner.

First, in FIG. 2, at the top of the diagram showing time 0, the permanent magnet 1-1 on the cylinder side and the rotor permanent magnet 2-1 are extremely close to each other and stop due to a braking force. In state. This is the first ground state. Next, in order to cause rotation, the electromagnets 3-1 and 3-4 are energized,
Magnetic attraction occurs between the rotor permanent magnets 2-1 and 2-3, respectively. As a result, the rotor moves to the right in FIG. 2, and in FIG.
It is shown as a displacement of -1 to 2-4. This allows
When rotated by 15 degrees or more, the permanent magnet 1-2 on the cylinder side and the permanent magnet 2-2 on the rotor side are closer to the permanent magnet 1-1 on the cylinder side and the permanent magnet 2-1 on the rotor side. Therefore, even if the power of the electromagnets 3-1 and 3-4 is turned off, the motor naturally transitions to the second ground state. Thus, one step of the present stepping motor is completed. It can be seen that the interval between the magnets fixed on the cylinder side is 40 degrees, but the rotation angle between the ground states (stopped state) is 30 degrees.

Next, another embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a cross-sectional view of a main part of another embodiment of the stepping motor according to the present invention, showing the motor in a ground state. In FIG. 3, reference numeral 4 denotes a cylindrical cylinder of a motor;
Is a rotating shaft, 1-1, 1-2 and 1-3 are permanent magnets fixed to the inner surface of the rotating shaft 5 of the motor, 2-1 2-2,2-
3 and 2-4 are permanent magnets fixed to the inner surface of the cylinder 4; 3-1, 3-2, 3-3, 3-4, 3-5 and 3-6 are electromagnets fixed to the rotating shaft 5. , 6 are pedestals for fixing the magnet to the rotating shaft 5. Here, the magnet fixed to the rotating shaft 5 is (1-1)-(3-1)-(3-2)-(1-2)
-(3-3)-(3-4)-(1-3)-(3-5)-
They are arranged at equal intervals (every 40 degrees) in the order of (3-6).

The operation of the above configuration will be described below. In the state of FIG. 1, the permanent magnet 1-1 on the rotating shaft and the permanent magnet 2-1 on the cylinder side are close to each other, generate a braking force, and are in a stopped state. This state is the first ground state. Next, the motor rotates clockwise by one step, and the permanent magnets 1-3 are rotated.
And a transition to the second ground state where the permanent magnet 2-4 comes closest (rotates by 30 degrees), and this state will be described in detail. First, the electromagnets 3-1, 3-2, 3-3, 3-4, 3-5 and 3
As long as -6 is not energized, the motor will try to remain in the first ground state. Next, the electromagnets 3-2 and 3-3 are energized to attract the permanent magnets 2-2 and 2-3. Thereby, the rotating shaft 5
Is rotated by 15 degrees or more to exceed the transition state. Then, the permanent magnet 2 is more than the permanent magnet 1-1 and the permanent magnet 2-1.
-4 and the permanent magnet 1-3 are closer, so that the motor naturally transitions to the second ground state. Thus, one step rotation of the stepping motor is completed.

Also, in the case of the stepping motor in which the electromagnet is provided on the rotor side, as in the case of the first embodiment described above, the stepping motor which requires a high-precision stop position accuracy is reduced in size. Therefore, it is possible to solve the contradiction that the stop position accuracy is deteriorated due to the limitation of the number of magnets that can be arranged.

[0017]

【The invention's effect】

According to the first aspect of the present invention, the number of permanent magnets on the stator side and the rotor side is set to be relatively prime and each side is set to be 2 or more. It is possible to provide a motor capable of performing stop control of the motor at the stop position, achieving high control accuracy, consuming no power, and enabling downsizing. Effects of Claims 2 and 3 In addition to the effects of claim 1, the present invention provides a means necessary for realizing a motor such as a stepping motor. The step operation from step to the next ground state is enabled by controlling the energization of the electromagnet.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of a stepping motor according to the present invention, showing the motor in a ground state.

FIG. 2 is a chart illustrating a transition of an operation state of a stepping motor according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of another embodiment of the stepping motor according to the present invention, showing the motor in a ground state.

FIG. 4 is a diagram schematically showing a structure of a conventional example of a permanent magnet type stepping motor.

FIG. 5 shows a conventional example of a double permanent magnet type stepping motor using permanent magnets for both a cylinder and a rotor.

[Explanation of symbols]

1-1 to 1-3, 1'-1 to 1'-4, 2-1 to 2-
4, 2 ', 2 "permanent magnet, 3-1 to 3-6, 3'-1
~ 3'-4 ... electromagnet, 4,4 '... fixed cylinder,
5, 5 ': rotating shaft, 6: pedestal.

Claims (3)

[Claims] 1. A double permanent magnet motor in which permanent magnets are arranged at regular intervals along the rotation direction on the stator side and the rotor side so that an attractive force can act on the magnets on both sides. A double permanent magnet motor, wherein the number of the permanent magnets on the stator side and the rotor side is set to be relatively prime and each side is set to be two or more. 2. The interrelationship between the stator and the rotor changes from one ground state caused by the action of an attractive force acting between the pair of permanent magnets on the stator side and the rotor side to the next cycle through a transition state. 2. The double permanent magnet motor according to claim 1, wherein an electromagnet capable of excitation control for generating an attractive force and / or a repulsive force is provided between the permanent magnet and the permanent magnet so as to reach a ground state. 3. The double permanent magnet motor according to claim 2, wherein the electromagnet capable of controlling the excitation is provided on one of a stator side and a rotor side.