JPH04229065A - Miniature motor - Google Patents

Abstract

PURPOSE:To constitute the entirety of a motor into an elongated cylinder having compact structure by arranging a pair of stators at the opposite sides on the axis while shifting relatively by half of the pole pitch with a rotor being interposed. CONSTITUTION:Upon supply of exciting current to the exciting coils 42, 52 of stators 4, 5, pole pieces 43, 53 are magnetized with N pole or S pole and four N poles and S poles are arranged alternately on the periphery of a permanent magnet rotor 1 which thereby attracted or repelled magnetically. The rotor 1 is rotated by controlling the exciting current. The stators 4 and 5 are arranged while being shifted in the peripheral direction by half of the pole pitch of the rotor 1. Consequently, when a motor is assembled, the pole pieces 43 on the stator 4 side and the pole pieces 53 on the stator 5 side are arranged alternately while opposing to the peripheral surface of the rotor 1 resulting in a motor having elongated profile and compact structure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-small motor with a diameter of several millimeters that is used by being incorporated into watches, cameras, medical catheters, and the like.

0002

2. Description of the Related Art First of all, FIGS. 8 and 9 show the conventional structure of a small motor used in a watch, camera, etc. In the figure, 1 is a permanent magnet rotor that is magnetized so that N and S poles are arranged alternately in the circumferential direction (the example shown is 2 poles), and 2 and 3 are both ends on the shaft with rotor 1 in between. A pair of left and right stators are lined up. Here, each stator 2, 3 consists of a C-shaped yoke 21, 31 with a part of the frame shape cut out, and excitation coils 22, 32 wound around the yoke.
The end faces of the notches are machined into arcuate surfaces, and magnetic poles 23, 24 and 33, 34 facing the circumferential surface of the rotor 1 are formed so as to be alternately arranged at a pitch angle of 90°. In addition, bearings 25 and 35 are provided on the yokes of each stator 2 and 3, and the rotary shaft 11 protruding from both ends of the rotor 1 is inserted therein to be pivotally supported.

When a current is passed through the excitation coils 22 and 32 in this configuration, the magnetic poles 23 and 2 have polarities corresponding to the direction of the current.
4, 33, and 34 are magnetized, and N and S poles appear. Here, each exciting coil 2 is connected via a drive circuit (not shown).
By applying a drive timing pulse to 2 and 32 and controlling the energization, the rotor 1 is rotationally driven as follows. That is, in the state shown in FIG. 9(a), the rotor 1 is connected to the stators 2 and 3.
It rotates in the direction of the arrow shown in the figure due to the magnetic force acting between it and the magnetic pole. Then, when the current direction of the excitation coils 22 and 32 is reversed when the state shown in FIG.
The polarities of 3, 24 and 33, 34 become as shown in FIG. 3(c), and the rotor 1 continues to rotate further.

0004

[Problems to be Solved by the Invention] By the way, in the configuration of the conventional small motor described above, a yoke with a frame-shaped magnetic path is used as the stator yoke, so the yoke and excitation coil are located laterally than the rotor. It protrudes greatly. Therefore, there is a limit to reducing the external dimensions of the motor as a whole, and the space efficiency when incorporating it into equipment such as a camera is poor, and it is particularly unsuitable for applications such as being incorporated into a thin tube such as a medical catheter.

The present invention has been made in view of the above points, and an object of the present invention is to provide a small motor that has a compact structure and can be constructed in the form of an elongated cylinder by improving the stator. do.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the small motor of the present invention has a pair of stators disposed on both sides of the shaft with the rotor in between, arranged coaxially with the rotor shaft. It consists of a cylindrical yoke, an excitation coil wound around the outer periphery of the yoke, and comb-shaped magnetic poles extending over the circumferential surface of the rotor with one end connected to the yoke. The magnetic poles are arranged so as to be relatively shifted by 1/2 of the magnetic pole pitch in the direction.

Further, in the above structure, the rotating shaft protruding from both ends of the rotor can be inserted into the shaft hole of the cylindrical yoke and supported.

Furthermore, as a specific configuration of the stator, the stator includes a cylindrical yoke, an excitation coil loaded on the circumference of the cylindrical yoke, and a stator fitted to both ends of the cylindrical yoke with the excitation coil sandwiched therebetween. A magnetic pole piece assembled from a pair of flanged yokes and arc plate-shaped magnetic pole pieces arranged so as to extend over the circumferential surface of the rotor with one end connected to each flanged yoke, and coupled to one of the flanged yokes. There is a configuration in which the pitch between the magnetic pole pieces coupled to the yoke and the other flanged yoke is arranged alternately in the circumferential direction so as to match the pitch of the magnetic poles of the rotor.

In addition, as a means for assembling and holding each of the stators in a fixed position with precision, the stators arranged on both sides of the rotor are assembled in a non-magnetic sleeve-shaped outer case that extends between them; There is a structure in which a sleeve-shaped outer case is formed with a fitting groove on the inner peripheral surface thereof to hold each magnetic pole piece of the stator in a fixed position.

0010

[Operation] In the above structure, the rotor rotates on the same principle as a normal step motor by switching the current flowing through the excitation coil of each stator over time to achieve bipolar drive. In addition, the stator assemblies placed on both sides of the rotor are coaxial with the rotor and have a cylindrical shape, so there are no protruding parts in the radial direction, and the entire motor is shaped like an elongated cylinder. Can be configured compactly. Further, by incorporating each stator into the sleeve-shaped outer case, the stator and rotor can be positioned with high accuracy and assembled with their axes aligned based on the outer case.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. In each embodiment, the same members corresponding to FIG. 8 are given the same reference numerals.

Embodiment 1: FIGS. 1 and 2 show a basic embodiment of the present invention. FIG. 1 is an exploded perspective view of the entire motor, and FIG. 2 shows the magnetic pole arrangement in an assembled state. That is, stators 4 and 5 of the same structure are coaxially arranged on both sides of a permanent magnet rotor 1, which is magnetized so that N and S poles (number of poles are 8) are aligned in the circumferential direction. They are placed facing each other at the top. Further, the stators 4 and 5 have cylindrical yokes 41 and 51, excitation coils 42 and 52 wound around the circumferential surface of the small diameter portion on the rear end side of the yokes, and cylindrical yokes 41 and 5.
four magnetic pole pieces 43 each extending from the rear end of the rotor 1 (on the side opposite to the excitation coil) and arranged in a comb-teeth shape on the circumferential surface of the rotor 1;
It is composed of 53. Here, the magnetic pole pieces 43 and 53 are arranged on the circumference according to the magnetic pole pitch of the rotor 1, and the stators 4 and 5 are arranged on the circumference according to the magnetic pole pitch of the rotor 1.
1 of the magnetic pole pitch so that 3 mesh with each other and combine.
They are arranged with a relative shift of /2 in the circumferential direction. In the assembled state in which the rotor 1 is inserted into the inner cavity surrounded by the magnetic pole pieces 43, 53 of the stators 4, 5, the rotating shaft 11 protruding from both ends of the rotor 1 is connected to the cylindrical yokes 41, 51.
The shaft is supported by shaft holes 44, 54 bored in the center thereof as bearings.

With this configuration, when an excitation current is passed through the excitation coils 42, 52 of the stators 4, 5, the magnetic pole pieces 43, 53 are magnetized to either the north pole or the south pole depending on the direction of the excitation current. In the state shown in FIG. 2, the magnetic pole piece 43 of the stator 4 is magnetized to the north pole, and the magnetic pole piece 53 of the stator 5 is magnetized to the south pole.There are four N poles and four S poles on the circumference of the rotor 1. Since the magnetic pole pieces of the poles are arranged alternately, magnetic attractive force and repulsive force are exerted between the magnetic pole pieces and the permanent magnet type rotor 1. And the excitation coil 43 of each stator 4, 5
, 53 is switched and controlled over time through a pulse distributor of a drive circuit (not shown), the polarity of each magnetic pole piece 43, 53 changes between N and S, and in synchronization with this, the rotor 1 rotates. The principle of this rotation operation is similar to that of a step motor. In this case, in principle, there is no starting rotational force for the motor, but small motors that require extremely small torque are generally started by the torque generated by the eddy current that occurs when the polarity of the magnetic poles is reversed, and once started, they will not rotate. The inertia of the child is added and it rotates continuously in a fixed direction.

Embodiment 2: FIGS. 3 to 7 show the structure of an embodiment of the present invention which is a further embodiment of the above-mentioned embodiment 1. That is, the motor includes a permanent magnet rotor 1 (number of magnetic poles: 4) similar to that described in Embodiment 1, and stators 6 and 7 of the same structure arranged coaxially with the rotor 1 and facing each other on both left and right sides. , and a sleeve-shaped outer case 8 that spans both of the stators 6 and 7 and is assembled on the outer peripheral side thereof. Furthermore, the stators 6 and 7 have cylindrical yokes 61 and 71.
, excitation coils 62 and 72 loaded on the circumference of the yoke, and cylindrical yokes 61 and 7 with the excitation coils 62 and 72 in between.
Flange-like yokes 63, 64 and 74 fitted to both ends of 1
, 75, and arc plate-shaped magnetic pole pieces 65, 66 and 75, 76, each of which has one end connected to each of the flanged yokes 63, 64 and 74, 75, and extends two pieces each over the circumferential surface of the rotor 1. It becomes a three-dimensional object.

Here, with the magnetic pole pitch τP of the rotor 1 as a reference, as shown in FIG.
The pitch is set to be the same as that of P, and the stators 6 and 7 are arranged to be relatively shifted by 1/2 of the magnetic pole pitch τP in the circumferential direction. In addition, each magnetic pole piece 65 and 66, and 75
The circumferential width dimensions of and 76 are approximately 1/2 of the magnetic pole pitch τP. As a result, when the motor is assembled, an alternate arrangement is formed in which the magnetic pole pieces 75 and 76 on the stator 7 side are lined up between the magnetic pole pieces 65 and 66 on the stator 6 side facing the circumferential surface of the rotor 1. Become. In addition, in the assembled state of the motor, as in Example 1,
The rotating shaft 11 protruding from both ends of the rotor 1 connects the stators 6 and 7.
The shaft is supported by shaft holes 67 and 77 bored in the center of the cylindrical yoke as bearings. In addition, the rotor 1 and stators 6 and 7
Collars 68, 78, which function as thrust bearings, are inserted between the end faces of the cylindrical yokes 61, 71.

On the other hand, the sleeve-shaped outer case 8 described above
is a non-magnetic case made of an aluminum die-cast product or a resin molded product, and as shown in FIG. , 76 in a predetermined assembly position.
is formed. Note that instead of forming the fitting groove 81, the magnetic pole pieces may be integrally molded when the outer case 8 is molded.

With the above configuration, when the exciting coils 62 and 72 are energized for each of the stators 6 and 7, the magnetic poles 65 and 66 and 75 and 76 are magnetized to N and S poles in accordance with the direction of the current. When the current direction of the excitation coil is switched with
, 66 and 75, 76 are reversed. In this case, each stator 6, 7 has a cylindrical yoke, a brim-shaped yoke,
A closed loop magnetic path is formed via the pole pieces. The motor rotates by controlling the excitation coils 62 and 72 of the stators 6 and 7 to be energized as shown in the operating principle diagram of FIG. That is, in step 1 of FIG. 7, the excitation coil of the stator 6 is energized, the excitation coil of the stator 7 is not energized, and the magnetic poles 65 and 66 of the stator 6 are S and N poles, respectively. In this state, the magnetic poles 6 of rotor 1 and stator 6
5 and 66 are balanced and no rotational force is generated. From this state, when the stator 6 is de-energized and the stator 7 is energized as in step 2, the rotor 1 is moved by the magnetic attraction force acting between the rotor 1 and the magnetic poles 75 and 76 of the stator 7. 1/2 of the magnetic pole pitch τP in the direction of the arrow
only rotates. Thereafter, the rotor 1 rotates continuously in steps by sequentially switching and controlling the energization of the stators 6 and 7 and the current direction to the states of steps 3 to 5.

Although the motor of the illustrated embodiment is configured as a two-phase step motor of a four-pole bipolar drive system, there is no limit to the number of magnetic poles of the stator in terms of operating principle. However, if the stators 6 and 7 are composed of two poles, the magnetic pole 65
, 66 and 75, 76, it is not possible to stably center the rotating shaft when it is assembled into the outer case 8. Therefore, it is practically preferable to configure it with 4 to 6 or more poles.

[0019]

[Effects of the Invention] Since the small motor of the present invention is constructed as described above, it achieves the following effects.

(1) In the structure of claim 1, a pair of stators arranged on both sides of the shaft with the rotor sandwiched therebetween are connected to a cylindrical yoke coaxially aligned with the rotor shaft and wound around the outer periphery of the yoke. It consists of an excitation coil equipped with a magnetic pole, and a comb-shaped magnetic pole that extends over the circumferential surface of the rotor with one end connected to the yoke.
Furthermore, in the configuration of claim 2, the rotary shaft protruding from both ends of the rotor is inserted into the shaft hole in the cylindrical yoke and is pivotally supported, so that the overall external shape of the motor is elongated. Since the motor has a compact structure, it is possible to incorporate the motor into the applicable equipment in a space-efficient manner, and the range of applications can be expanded, for example, by making it possible to apply it inside small tubes such as medical catheters.

(2) Furthermore, by adopting the configurations of claims 3, 4, and 5, a closed loop magnetic path is secured for each stator via the cylindrical yoke, the brim-shaped yoke, and the magnetic pole pieces. In addition to stable operation, the motor can be easily assembled by incorporating a pair of stators into the outer case, and each component can be positioned and centered with great precision.

[Brief explanation of the drawing]

FIG. 1: An exploded perspective view showing the configuration of an embodiment of the present invention.

[Figure 2
】Arrangement diagram of magnetic poles in Figure 1

FIG. 3 is a partially cutaway perspective view showing the configuration of a different embodiment of the present invention.

[Figure 4] Cross-sectional side view of Figure 3

[Figure 5] A perspective view of the stator assembly structure in Figure 3.

[Figure 6
] End view of the outer case in Figure 3

[Fig. 7] An explanatory diagram of the operation of the motor with the configuration shown in Fig. 3.

[Figure 8] Exploded perspective view of a conventional small motor

[Fig. 9] An explanatory diagram of the operation of the motor with the configuration shown in Fig. 8.

[Explanation of symbols]

1 Permanent magnet rotor 11 Rotation axis 4 Stator 41 Cylindrical yoke 42 Excitation coil 43 Magnetic pole piece 44 Shaft hole 5 Stator 51 Cylindrical yoke 52 Excitation coil 53 Magnetic pole piece 54 Shaft hole 6 Stator 61 Cylindrical yoke 62 Excitation coil 63 Flange-shaped yoke 64 Flange-shaped yoke 65 Magnetic pole piece 66 Magnetic pole piece 67 Shaft hole 7 Stator 71 Cylindrical yoke 72 Excitation coil 73 Flange-shaped yoke 74 Flange-shaped yoke 75 Magnetic pole piece 76 Magnetic pole piece 77 Shaft hole

Claims (5)

[Claims] Claim 1: A permanent magnet rotor having N and S poles magnetized in the circumferential direction, and a pair of stators disposed on both sides of the shaft with the rotor in between, each stator being excited. A small motor that drives a rotor by controlling energization of a coil, the stator having a cylindrical yoke arranged coaxially with the rotor axis, an excitation coil wound around the outer periphery of the yoke, and one end connected to the yoke. and comb-shaped magnetic poles protruding on the circumferential surface of the rotor, and both stators are arranged at 1/2 of the magnetic pole pitch relative to each other in the circumferential direction.
A small motor characterized by being arranged in a staggered arrangement. 2. The small-sized motor according to claim 1, wherein the rotating shaft protruding from both ends of the rotor is inserted into a shaft hole in a cylindrical yoke and pivotally supported. 3. The ultra-compact motor according to claim 1, wherein the stator includes a cylindrical yoke, an excitation coil loaded on the periphery of the cylindrical yoke, and is fitted to both ends of the cylindrical yoke with the excitation coil sandwiched therebetween. It is an assembly of a pair of flanged yokes, and arcuate plate-shaped magnetic pole pieces arranged so as to extend over the circumferential surface of the rotor, with one end connected to each flanged yoke, and coupled to one of the flanged yokes. A small motor characterized in that the magnetic pole pieces connected to the other flanged yoke are alternately arranged in the circumferential direction so that the pitch between the magnetic pole pieces is matched to the magnetic pole pitch of the rotor. 4. The small-sized motor according to claim 3, wherein the pair of stators are incorporated in a non-magnetic sleeve-shaped outer case that extends between the two stators. 5. The small motor according to claim 4, wherein fitting grooves are formed on the inner peripheral surface of the outer case for holding each magnetic pole piece of the stator in a fixed position.