JP2002345227A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a space for the motor magnet of a stepping motor, to realize increase of its speed and output, and to carry out cost reduction by enabling common use of rotor magnets when developing new motors. SOLUTION: Projecting spaces are formed on the rear lid and the bottom surface of the cylindrical case of the stepping motor, over the outside diameter of the columnar rotor magnet of the stepping motor. Or, a hole is bored on the bottom surface of the cylindrical case over the outside diameter of the columnar rotor magnet, and a rotor magnet which is made longer in a thrust direction by a length corresponding to the board thickness of the case, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor which is thin and requires high speed, high output, low noise and low cost.

[0002]

2. Description of the Related Art In a conventional structure, FIGS.
As shown in the figure, the bottom of the cylindrical case 3 (or 3A) or the rear lid 2 (or 2A) is obtained by stacking four stators 6A to 6D and two bobbins 4A and 4B in the axial direction. ) Magnet part 1 so that it does not contact the flat part
A magnetic circuit was formed by using a columnar (cylindrical) roller having a shorter (or 1A) length.

[0003]

In a motor requiring high speed and high output, how to generate a high magnetic force between the rotor magnet and the stator comb teeth in forming a magnetic circuit is a problem to be developed. However, in the prior art, since the bottom surface of the cylindrical case and the rear lid have a planar shape, the dimension in the thrust direction of the rotor magnet 1A inserted into the cylindrical case is as shown in FIG. Naturally, four stators (only two stators 6C and 6D are shown) and two bobbins (only one bobbin 4B is shown)
Have to be made smaller than the thrust dimensions of the stack. Further, when developing a motor thinner than the conventional one, it is necessary to newly develop a rotor magnet for the above reason.

Accordingly, an object of the present invention is to make the bottom of the cylindrical case and the rear lid convex, or to form a hole in the bottom of the cylindrical case in order to alleviate the restriction on the size of the rotor magnet in the thrust direction. To secure the space for the rotor magnet and to achieve high speed and high output of the stepping motor by making the rear lid flat part convex, and to use a common rotor magnet for new motor development. The goal is to reduce costs.

[0005]

As a means for achieving the above object, the present invention relates to a stepping motor, which has a cylindrical case bottom surface and a rear cover that are convex over a range corresponding to the outer diameter of a cylindrical rotor magnet. In this structure, a rotor-shaped space is provided, and a rotor magnet larger than the conventional thrust size is used.

[0006] Further, as means for the same purpose, there is used one in which a hole is formed in the bottom of the cylindrical case over a range corresponding to the outer diameter of the cylindrical rotor magnet, and the rotor magnet is extended in the thrust direction by the thickness of the case. I do.

[0007] With these structures, it is possible to arrange a rotor magnet having a large dimension in the thrust direction with respect to a stator in which four stators and bobbins are stacked in the thrust direction. The teeth can be opposed over the entire surface. As a result, the magnetic resistance is reduced, and the motor characteristics can be improved. In addition, since the space can be secured, the commonly used rotor magnet can be commonly used, and the effect of cost reduction can be obtained.

[0008]

(Embodiment 1) FIG. 1 is a sectional view of Embodiment 1 of a stepping motor using the present invention. The first embodiment shows an example in which a convex space is provided on the bottom surface of the cylindrical case 3B and the flat surface of the rear cover 2B. With this configuration, the size of the cylindrical rotor magnet in the thrust direction (axial direction) can be made larger than the total size of the stacked stator and bobbin, thereby reducing magnetic resistance and improving motor characteristics. Can be realized.

FIG. 2 is a sectional view of a stepping motor according to a second embodiment of the present invention. In the second embodiment, the cylindrical rotor magnet 1C is provided on the bottom surface of the cylindrical case 3C.
An example is shown in which a hole is made in a range corresponding to the outer diameter of the rear cover 2 and a convex space is provided in the plane portion of the rear cover 2C. FIG. 3 is an enlarged view of a portion where a hole is formed in the bottom surface of the cylindrical case 3C. As a comparison, the cylindrical case portion 3A shown in FIG. It has a 3C shape in FIG. 3 in which holes are formed over the range, and has a structure in which the rotor magnet is extended by the thickness of the case. In the embodiment, the motor is covered with the mounting plate 7.

[0010]

As described above, according to the present invention, the loss of the magnetic field generated by applying a voltage to the winding wound on the bobbin and causing a current to flow is suppressed without changing the shape of the bobbin or the stator. It is intended to realize a high speed and high output of a stepping motor, and to realize a common rotor magnet in developing a new motor, thereby realizing cost reduction.

[Brief description of the drawings]

FIG. 1 is a sectional view of a stepping motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a stepping motor according to a second embodiment of the present invention.

FIG. 3 is an enlarged view of a rotor magnet, stator comb teeth, a case, and a mounting plate portion according to a second embodiment.

FIG. 4 is a sectional view of a conventional example.

FIG. 5 is an exploded perspective view of a conventional stepping motor.

FIG. 6 is an enlarged view of a rotor magnet / stator comb teeth / case portion of a conventional example.

[Explanation of symbols]

 1 (1A, 1B, 1C) Rotor magnet 2 (2A, 2B, 2C) Back lid 3 (3A, 3B, 3C) Case 4 (4A, 4B) Bobbin 5 Winding 6 (6A, 6B, 6C, 6D) Stator 7 Mounting plate

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuko Koyama 2-4-19 Nakane, Meguro-ku, Tokyo Canon Seiki Co., Ltd. F-term (reference) 5H605 AA07 BB05 CC01 CC02 DD03 5H622 CA01 CA07 PP01

Claims (4)

[Claims] 1. A stator comprising a plurality of stators made of comb-shaped copper plates opposed to a cylindrical rotor, and a resin bobbin for winding a coil around the outer periphery of the stator is laminated in the axial direction. A stepping motor in which both are inserted into a cylindrical case to form a magnetic circuit, wherein the size of the rotor magnet in the thrust direction is increased in order to obtain a high magnetic force. 2. The stepping motor according to claim 1, wherein the bottom surface of the cylindrical case and the flat portion of the rear lid are formed in a convex shape for incorporating the rotor magnet. 3. A stepping motor according to claim 1, wherein a hole is formed in a bottom surface of a cylindrical case for incorporating said rotor magnet, and a flat portion of a rear lid is made convex. 4. A stepping motor according to claim 1, wherein the cost is reduced by the use of common parts, and a row magnet is incorporated in which the dimension in the thrust direction is larger than the lamination dimension of the coil bobbin and the comb teeth of the stator. A stepping motor characterized in that the bottom surface of the cylindrical case and the flat portion of the rear lid are convex or the flat surface portion of the rear lid is convex by making a hole in the bottom surface of the cylindrical case.