JPH0139109Y2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention relates to a stepping motor, and relates to the configuration of a magnetic path between a yoke and a frame, in which a coil is sandwiched between the yoke and the frame.

(2) Conventional technology and its problems In the conventional stepping motor of this type,
A pair of yokes with a coil sandwiched between them are fitted into a frame made of magnetic material such as iron, and a magnetic path is formed between the outer periphery of the pair of yokes and the inner periphery of the frame. A structure is adopted in which an annular flange is formed on the periphery to fit into the coil and contact the inner circumferential surface of the frame. With this structure, a slight gap is created between the inner circumferential surface of the frame and the outer circumferential edge of the yoke due to errors in component dimensions and assembly work, which increases magnetic resistance and reduces motor efficiency. The annular flange must be formed by drawing, which increases costs.

(3) Purpose of the invention The present invention was developed in view of the above-mentioned drawbacks, and it improves the efficiency of the motor by lowering the magnetic resistance by making the outer peripheral edge of the yoke fitted into the frame tightly contact the inner surface of the frame. The present invention provides a stepping motor that can be obtained at low cost.

(4) Structure of the invention The invention consists of a cylindrical frame molded from a magnetic material, a coil fitted into the frame, and a coil fitted into the frame with the coil in between and protruding from the inner peripheral edge. a pair of yokes with a plurality of magnetic pole pieces arranged alternately along the inner periphery of the yoke; A rotor is provided, and a magnetic path forming body foamed by heat and having magnetism is disposed between the frame and the outer circumferential portion of a pair of yokes.

(5) Embodiment of the invention Next, the configuration of an embodiment of the invention will be explained with reference to the drawings.

Reference numeral 1 denotes a frame formed into a cylindrical shape by deep drawing from a magnetic material such as an iron plate.A bearing 2 is provided at the center of the bottom of the frame 1, and a lead wire extraction hole is provided on the circumferential surface, which is open at the opening edge. An engagement groove 3 that also serves as a lock is formed in the axial direction. Further, a mounting plate portion 4 is formed to be bent outward at the opening edge of the frame 1.

Next, 5 and 6 are a pair of stators, each stator 5 and 6
Each includes a coil 7 and a pair of yokes 8 and 9. This coil 7 is coil bobbin 1
It is wound to 0. A positioning protrusion 11 that is engaged with the engagement groove 3 of the frame 1 is integrally formed on one of the flanges 10 _a of the coil bobbin 10 . Further, the protrusions 1 are provided on both sides of the bobbin 10.
A protruding engagement portion 12 is formed at a position offset by a half step angle (θ°/2) in the circumferential direction from a line _l1 connecting the center and the center.

Next, the pair of yokes 8 and 9 have the same shape and are each formed into a flat annular shape.
A plurality of magnetic pole pieces 13 are cut and raised from the inner circumferential edge of the magnetic pole piece 9 at right angles and at equal intervals in the circumferential direction. Further, the pair of yokes 8 and 9 are deviated by one step angle (θ°) in the circumferential direction from the line _l2 connecting the center with any magnetic pole piece 13, and are engaged with the engaging portion 12 of the bobbin 10. A hole-shaped engaged portion 14 is formed.

Next, reference numeral 15 denotes a circular plate-shaped cover, and a bearing 16 is provided in the center.

A rotor 17 is formed of a multi-pole magnet, and a rotating shaft 18 of the rotor 17 is connected to the magnetic pole pieces 1 of the yokes 8 and 9 by the bearings 2 and 16.
3, 13 so that it can be rotated.

Next, reference numeral 19 denotes a magnetic path forming body mainly made of synthetic resin foamed by heat, which is wound around the outer periphery of the pair of yokes 8 and 9 in the form of a tape and fitted into the frame 1. It is becoming more and more like this. After the motor is assembled, the magnetic path forming body 19 is foamed to expand its volume by heating, and is closely wedged between the frame 1 and the outer periphery of the yokes 8 and 9. It is designed to form a magnetic path between the two.

Next, a method of assembling this embodiment will be explained.

The coil 7 wound around the bobbin 10 is sandwiched between the pair of yokes 8 and 9 by inserting the magnetic pole pieces 13 and 13 into the hollow part of the coil 7, and the engaging parts 1 on both sides of the bobbin 10 are sandwiched.
2 are engaged with the engaged portions 14 of the yokes 8 and 9 to form stators 5 and 6, respectively.
A magnetic path forming body 19 is wound in a tape shape around the outer peripheral edges of the yokes 8 and 9. The first stator 5 is fitted into the frame 1 in such a direction that the collar portion 10 _a of the bobbin 10 on which the alignment protrusion 11 of the bobbin 10 is formed is positioned upward. At this time, the alignment protrusion 11 of the bobbin 10 is engaged with the engagement groove 2 of the frame 1, and the magnetic pole pieces 13, 13 of the yokes 8, 9 are positioned.

Next, the frame 1 is oriented such that the collar portion 10 _a of the bobbin 10 on which the positioning protrusion 11 of the bobbin 10 is formed is positioned downward so that the second stator 6 is in a reversed state with respect to the first stator 5. Fits in. At this time, the alignment protrusion 11 of the bobbin 10 is similarly engaged with the engagement groove 3 of the frame 1, and the magnetic pole pieces 13 of the yokes 8 and 9 are positioned.

Next, the rotor 17 is placed in the space formed by the magnetic pole pieces 13, 13 of the yokes 8, 9 of both stators 5, 6.
, one end of the rotating shaft 18 is rotatably supported on the bearing 2 of the frame 1 , then the cover 15 is fitted on the frame 1 , and the other end of the rotating shaft 18 is supported on the bearing 2 of the frame 1 .
It is inserted into the bearing 16 and is supported. Next, the cover 15 is caulked and fixed to the frame 1.

In this way, the yoke 8 of each stator 5, 6,
Each of the magnetic pole pieces 13, 13 of 9, 8, and 9 is positioned corresponding to one step angle (θ°).

Next, when the whole is heated, the magnetic path forming bodies 19, 1
9 is foamed to increase its volume, and a magnetic path forming body 1 is formed between the inner peripheral surface of the frame 1 and the outer peripheral edge of the yokes 8 and 9.
9 and 19 are wedge-shaped to form a magnetic path.

In this state, by energizing the coils 7, 7 of both stators 5, 6, the rotor 17 is rotated by one step angle (θ°).

In the configuration of this embodiment, it is only necessary to fit the stators 5 and 6 to the frame 1, and each stator 5,
6 is assembled by simply sandwiching the coil bobbin 10 between the yokes 8 and 9, without using any jigs, and by positioning each magnetic pole piece 13 of the yokes 8, 9, 8, and 9. The positional accuracy of the piece 13 is improved,
There is no center deviation between bearings 2 and 6.

(6) Effects of the invention According to the invention, a magnetic path forming body foamed by heat and having magnetism is disposed between the outer peripheral edge of the yoke of the stator fitted to the frame and the frame. By heating, the magnetic path forming body is foamed and its volume increases, and the magnetic path forming body is wedge-shaped between the frame and the yoke, and due to dimensional errors and assembly errors between the frame and the yoke, Even if a gap occurs between the frame and the yoke, the magnetic path forming body is interposed, so there is no gap in the magnetic path between the frame and the yoke, the magnetic path resistance is low, and the motor efficiency can be improved. There is no need to form an annular flange around the periphery by drawing or the like, and it can be obtained at low cost.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of a stepping motor showing an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the same. 1... Frame, 7... Coil, 8, 9... Yoke, 13... Magnetic pole piece, 17... Rotor, 19...
...Magnetic path forming body.

Claims (1)

[Scope of utility model registration request] A cylindrical frame formed of a magnetic material, a coil fitted to this frame, and a coil fitted to the frame with the coil in between, protruding from the inner periphery and arranged alternately along the inner periphery of the coil. a pair of yokes provided with a plurality of magnetic pole pieces disposed thereon; and a rotor rotatably positioned and rotatably provided inside each magnetic pole piece of the pair of yokes and magnetized to have multiple poles; A stepping motor characterized in that a magnetic path forming body foamed by heat and having magnetism is disposed between a frame and an outer peripheral surface of a pair of yokes.