JPH0767313A - Stepping motor - Google Patents

Abstract

PURPOSE:To provide a stepping motor which can minimize the spring constant with a secure holding of a thrust member maintained. CONSTITUTION:A steel ball 22 is supported with the rotary shaft of a stepping motor 11. The steel ball 22 is in elastic contact with a plate-shaped thrust spring 14b, which is formed at a disk-shaped thrust member 14 that is fixed to a main body 12 by cutting up. The thrust member 14 and the main body 12 are positioned with projections 12a and 12a. Fixing points P1 and P2 located in the vicinities of cutting-up end parts 14c and 14c are preset under the positioned state so that the end parts are located at the outside of a pair of parallel lines H1 and H2, which are perpendicular to a rotary axial line 1 connecting the cutting-up end parts 14c and 14c and pass the cutting-out parts 14c and 14c. The thrust member 14 is fixed to the main body 12 by laser welding 24, 24... at a plurality of the fixing points including the fixing points P1 and P2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a stepping motor,
In particular, the present invention relates to a stepping motor which receives a thrust load by a leaf spring-shaped thrust spring.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, a coil 2 wound in a main body 1 and a drive that is rotatably supported by the main body 1 via a bearing 3 and has an outer peripheral surface 4a facing the coil 2. A disk-shaped thrust member 8 having a rotary shaft 5 to which a magnet 4 is coaxially fixed and a thrust spring 7 in which a steel ball 6 supported at an end of the rotary shaft 5 is elastically contacted to receive the thrust load of the rotary shaft 5. There is a stepping motor 10 including a disk-shaped cover plate 9 fixed to the main body 1 integrally with the thrust member 8.

The thrust spring 7 is cut and raised like a leaf spring so that the steel ball 6 makes elastic contact at approximately the center of the thrust member 8, and as shown in FIGS. 7A and 7B, the cut and raised end portion 7a. , 7
By rotating about a rotation axis L connecting a, the rotation shaft 5
The elasticity absorbs the thrust load from the. Also,
Engagement holes 8a, 8a ... Are formed in the peripheral edge portion of the thrust member 8 at the four equally divided points thereof.

The lid plate 9 is formed with a dome-shaped raised portion 9a which allows the rotational displacement of the thrust spring 7 due to the elastic contact of the steel balls 6. Engagement holes 9b, 9b ... Coaxial with the engagement holes 8a, 8a ... Are formed in the peripheral edge of the cover plate 9 so as to maintain the corresponding positional relationship between the thrust spring 7 and the raised portion 9a. .

On the other hand, the fixed surface 1 of the main body 1 (only the main part is shown)
In a, projections 1b, 1 are provided at fixed quadrant positions as fixed points.
b are protrudingly provided, and the engaging holes 8a, 8 are formed in the respective protrusions 1b, 1b.
a and the engaging holes 9b, 9b ... In the state of being engaged with each other, the projections 1b, 1b are formed by projection welding as fixing means.
The thrust member 8 and the cover plate 9 are fixed to the main body 1 by melting.

[0006]

By the way, when a thrust load is applied by such a thrust spring 7, an error in molding accuracy and assembling accuracy of each component of the stepping motor 10 including the spring set value of the thrust spring 7 is allowed. To achieve this, a longer spring length is advantageous because the spring load is stable.

That is, as shown in FIG. 6 (A), when a load is applied to the thrust spring 7 having a spring length a from the load center at which the steel ball 6 is elastically contacted to the rotation axis L, FIG. 6 (B) As shown in, the free end of the thrust spring 7 is rotationally displaced about the rotational axis L according to the load (direction of arrow A).

However, as shown in FIG.
Since the portion located at the peripheral end from the rotation axis L serves as a two-time spring which receives a reaction (in the direction of arrow B) according to the load received by the thrust spring 7, the spring length from the load center to the fixed point. b is the actual spring length of the thrust spring 7.

Therefore, in order to stabilize the spring load without changing the size or wall thickness of the thrust member 8, it is desirable to use the thrust spring 7 having the spring length c including the peripheral end portion.

Therefore, as shown in FIGS. 5 (A) and 5 (B), ribs 1c and 1 are formed at four equally divided points on the peripheral portion of the fixed surface 1a.
It is conceivable that c ... Are integrally projected and the ribs 1c, 1c ... Are fitted to the thrust member 8 and the cover plate 9.

However, in such a fixing structure, since the lid plate 9 is not provided with positioning means for engaging the ribs 1c, 1c ... In particular, the fixing point depends on the fixing position of the thrust member 8 and the fixing point is a product. Not only does this cause a new problem that the actual spring length is not constant, but also when the cover plate 9 is fixed at the regular fixing position, the fixing point is the center of the rotation axis L. Since it is located on the vertical line (spring center), the effective area as a two-time spring is limited at this fixed point, and as a result, it did not contribute to reducing the spring constant. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stepping motor capable of minimizing the spring constant while maintaining the reliable holding of the thrust member.

[0013]

In order to achieve the object, the present invention provides a coil wound inside a main body, and a rotary shaft rotatably supported by the main body and having a steel ball supported at one end thereof. A disk-shaped thrust member having a drive magnet coaxially fixed to the rotation shaft and having an outer peripheral surface facing the coil, and a leaf spring-shaped thrust spring cut and raised so that the steel ball makes elastic contact with the coil; A positioning unit that positions the member and the main body, and a fixing unit that fixes the thrust member to the main body at a plurality of preset fixing points in this positioning state, and among the plurality of fixing points It is preferable that the fixing point located near the cut-and-raised ends of the thrust spring is located outside a pair of parallel lines that are orthogonal to the rotation axis connecting the cut-and-raised ends and pass through the cut-and-raised ends. And

[0014]

In such a structure, the coil is wound inside the main body, the rotary shaft supporting the steel ball at one end is rotatably supported by the main body, and the drive magnet whose outer peripheral surface faces the coil is the rotary shaft. The steel ball is elastically contacted with a leaf spring-shaped thrust spring that is fixed coaxially to the disk-shaped thrust member by cutting and raising it, and the positioning member positions the thrust member and the main body. The fixed point located near the starting end is set in advance so as to be located outside a pair of parallel lines that pass through the cutting start part and are orthogonal to the rotation axis connecting the cutting start parts. The thrust member is fixed to the main body by the fixing means at the plurality of fixing points.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the stepping motor of the present invention will be described with reference to FIGS.

In FIG. 4, the stepping motor 11
The main body 12 includes a main body 12, a rotary shaft 13 having a tip protruding from the main body 12, a thrust member 14 fixed to the main body 12, and a cover plate 15.

The main body 12 includes an impregnated bearing 16 fixed to the base plate 15 to rotatably hold the rotary shaft 13, a yoke integrated stator frame 17 fixed to the base plate 15, and a bobbin 18 on the stator frame 17. The wound coils 19 are provided with a pin 20 and a flexible printed wiring board 21 for passing a current through the coils 19.

The fixing surface 17a of the stator frame 17 is provided with projections 12a, 12a as positioning portions for fixing the thrust member 14 and the cover plate 15 in a superposed state.

A steel ball 22 is supported on the base end (one end) of the rotary shaft 13. A drive magnet 23 is coaxially held on the rotary shaft 13. This drive magnet 23
The outer peripheral surface 23a faces the coils 19, 19 ...
The current flowing through the coils 19, 19 ... And the drive magnet 23
The magnetic flux of causes the drive magnet 23 to rotate integrally with the rotary shaft 13.

As shown in FIG. 1A, the thrust member 14 has engaging holes 14a, which engage with the protrusions 12a, 12a.
14a is provided. Further, the thrust member 14 is formed with a leaf spring-shaped thrust spring 14b formed in a U-shape in plan view by being cut and raised.

The cover plate 15 is provided with engaging holes 15a, 15a for engaging with the projections 12a, 12a. Further, the lid plate 15 is formed with a dome-shaped raised portion 15b that allows the rotational displacement of the thrust spring 14b.

The thrust member 14 and the lid 15 are the projections 12
a and 12a, engaging holes 14a, 14a and engaging holes 15a,
Laser welding 24, 24 ... As fixing means using a plurality of preset fixing points in a positioning state in which 15a is engaged.
By doing so, it is fixed to the stator frame 17 of the main body 12.

When performing this laser welding, FIG. 1 (B)
As shown in, the cut-and-raised end portion 14c of the thrust spring 14b,
The fixed points P1 and P2 set in the vicinity of 14c have the distance L1 between the fixed points P1 and P2 cut and raised ends 14c and 14c.
The cut-and-raised end portion 14c, so that it is longer than the distance L2 between
The cut-and-raised end portion 1 is orthogonal to the rotation axis L connecting between 14c and
It is set on the peripheral portion of the thrust member 14 located outside the pair of parallel lines H1 and H2 passing through 4c and 14c.

Further, since the fixed points P1 and P2 are set symmetrically with respect to the spring center so that the line connecting them is parallel to the rotation axis L, the left and right shown in the figure are kept stable. There is.

Further, as shown in FIGS. 2A and 2B, the two-time spring portion for reaction from the rotation axis L to the peripheral end portion of the thrust member 14 is shown in FIG. 5A. , (B)
The area of the present application (the shaded portion of FIG. 2A) can be secured to be wider than the area corresponding to the conventional type shown in FIG. 2 (the shaded portion of FIG. 2B), and the comparison graph of FIG. As shown in, the spring constant (A line) of the present application can be made significantly smaller than the conventional spring constant (B line).

In the above construction, when the assembly of the rotary shaft 13, the thrust member 14, and the cover plate 15 to the main body 12 is completed, the steel ball 22 makes elastic contact with the thrust spring 14b, and with this elastic contact, the thrust spring 14b becomes free. The end is pivotally displaced toward the lid plate 15 side.

The thrust load accompanying the rotation of the rotary shaft 13 is absorbed by the thrust spring 14b via the steel ball 22.

At this time, the thrust spring 14b has a long effective spring length, and the effective area of the two-hour spring can be widely used without being limited to the fixed point. Since the reaction of the peripheral portion of the member 14 is not restricted, the spring constant can be made small.

Therefore, it is possible to sufficiently deal with the movement of the load center of gravity caused by the molding error of the rotary shaft 13 or the like and the assembly error.

[0030]

With the stepping motor of the present invention having the above-described structure, the spring constant can be minimized while maintaining reliable holding of the thrust member.

[Brief description of drawings]

FIG. 1 shows a stepping motor of the present invention, (A) is a bottom view of the stepping motor, and (B) is an explanatory view of a main part.

2A is an explanatory view showing a deformable effective area of a reaction of the present application, and FIG. 2B is an explanatory view showing a deformable effective area of a conventional reaction of the present application.

FIG. 3 is also a graph comparing the spring constants of the present application and the related art.

FIG. 4 is a vertical sectional view of a stepping motor.

5A and 5B show a conventional stepping motor, in which FIG. 5A is a sectional view of a main part, and FIG. 5B is a bottom view of the stepping motor.

6 (A), (B) and (C) are explanatory views showing the spring action of the thrust spring over time.

FIG. 7 shows a conventional stepping motor, (A) is a cross-sectional view of a main part, and (B) is a bottom view of the stepping motor.

FIG. 8 is a vertical sectional view of a conventional stepping motor.

[Explanation of symbols]

 11 ... Stepping motor 12 ... Main body 12a ... Protrusion (positioning part) 13 ... Rotating shaft 14 ... Thrust member 14b ... Thrust spring 14c ... Cut and raised end 19 ... Coil 22 ... Steel ball 23 ... Driving magnet 23a ... Outer peripheral surface 24 ... Laser Welding (fixing means) P1 ... fixing point P2 ... fixing point H1 ... pair of parallel lines H2 ... pair of parallel lines L ... rotation axis

Claims (1)

[Claims] 1. A coil wound inside a main body, a rotary shaft rotatably supported by the main body and having a steel ball supported at one end, and an outer peripheral surface fixed to the coil coaxially with the rotary shaft. Drive magnets facing each other, a disk-shaped thrust member having a leaf spring-shaped thrust spring cut and raised so that the steel balls make elastic contact, a positioning portion for positioning the thrust member and the main body, and this positioning Fixing means for fixing the thrust member to the main body at a plurality of preset fixing points in a state, and the fixing point located in the vicinity of the cut and raised end portion of the thrust spring among the plurality of fixing points is A stepping motor, which is located outside a pair of parallel lines that are orthogonal to a rotation axis connecting the cut and raised ends and pass through the cut and raised ends.