JPH08196050A - Miniature motor - Google Patents

Abstract

PURPOSE: To obtain a miniature motor having a rotary shaft which does not penetrate the side plate and in which provision of a highly accurate protrusion for regulating the thrust rattle is not required. CONSTITUTION: The miniature motor comprises a stator, a rotor, and a side plate 5 for supporting the rotor while urging in the thrust direction. The side plate 5 is provided with a pre-load spring part 6 for supporting the rotary shaft 3 of the rotor while urging in the thrust direction, and a protrusion 11 for regulating the thrust rattling of the rotor. A part 9a for preventing the rotary shaft 3 from falling off the protrusion 11 is provided on the end face of the rotor facing the side plate 5 radially outward of the rotary shaft 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor such as a stepping motor. More specifically, the present invention relates to an improvement of a thrust bearing of a small motor that supports a rotor by urging the rotor in a thrust direction by a pressure spring of a side plate.

[0002]

2. Description of the Related Art Conventionally, a small motor in which a side plate supports a rotating shaft of a rotor has been known. For example, as shown in FIG. 10, a side plate 20 having a pressurizing spring portion 21 is used to support one end of the lead screw of a small stepping motor in the actual opening 1-2544 and the actual opening 2-37583. There is. The rotor 23 of such a motor has a radial runout as indicated by arrow A and arrow B as indicated by arrow B.
Such rattling in the thrust direction occurs during rotation of the rotor 23, transportation of equipment to which the motor is attached, and the like. Therefore, the rotary shaft 2 of the rotor 23 is attached to the side plate 20.
The projection 22 is provided so that the end face 25 of the No. 4 hits, and the thrust rattle is regulated. The rotary shaft 24 also serves as a lead screw.

[0003]

However, as shown in FIG.
In the small-sized motor as shown in (1), when the rotor 23 swings in the radial direction due to impact or other factors, a situation occurs in which the end surface 25 of the rotating shaft 24 comes off the front of the projection 22 and does not face it. When a force in the thrust direction toward the pressure spring portion 21 is applied to the rotor 23, the rotary shaft 24 may penetrate the side plate 20. This may cause a fatal problem that the small motor cannot operate because the rotor 23 is locked or the lead screw is disengaged from other members.

Further, the projection 22 has an end surface 25 of the rotary shaft 24.
Since it has to be installed so as to face the slightly flat surface portion 25a, high component accuracy and assembly accuracy are required for forming the projection 22 and assembling the side plate 20.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small motor in which the rotary shaft does not penetrate through the side plate and it is not necessary to increase the installation position accuracy of the thrust projections for restricting.

[0006]

To achieve the above object, the invention of claim 1 includes a stator, a rotor, and a side plate for supporting the rotor by biasing the rotor in a thrust direction with a pressurizing spring portion. In a small motor having a side plate of a rotor, a side plate is formed with a pressurizing spring portion for urging and supporting a rotating shaft of the rotor in a thrust direction and a protrusion for restricting thrust rattle of the rotor. A fall prevention portion is formed radially outward of the rotary shaft on the opposing end faces to prevent the rotary shaft from falling off the protrusion.

According to a second aspect of the present invention, in the small motor according to the first aspect, the rotating shaft and the magnet are integrated by a magnet holder to form a rotor, and the magnet holder is provided with a fall prevention portion. .

[0008]

Therefore, in the small motor according to the first aspect of the invention, the projection of the side plate is provided so as to face the end face of the rotary shaft or the drop-out preventing portion provided radially outward of the rotary shaft.
Even if the rotor swings largely in the radial direction, the drop-out preventing portion of the rotor maintains the state of facing the protrusion. Then, when thrust rattle occurs in the rotor, the drop-out preventing portion hits the protrusion, and the rotor is prevented from moving to the side plate side.

In addition, in the invention of claim 2, in the small motor according to claim 1, a rotor is formed by integrating a rotating shaft and a magnet by a magnet holder, and a fall prevention portion is formed on the magnet holder. Therefore, the magnet holder also serves to prevent the rotor from coming off.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 3 show an embodiment of the small motor of the present invention. As shown in FIG. 3, this small motor includes a stator 1 composed of two stator sets 1a and 1a and a rotor 2 arranged in the center thereof, and a part of a rotary shaft 3 of the rotor 2 has a lead screw 4 formed therein. It is a small stepping motor. The one end 3a of the rotary shaft 3 is supported by the pressurizing spring portion 6 of the side plate 5, and the other end 3b is supported by the frame 7. The other end 3b is supported by inserting a plurality of small balls 7b into a lid 7a fitted in a hole provided in the frame 7 and abutting the bearing balls 10 on the rotating shaft 3 side. There is.

Here, the rotor 2 is a metallic rotating shaft 3
And a magnet 8 and a magnet holder 9 made of resin that integrates the rotating shaft 3 and the magnet 8 by insert molding.
It is composed of Then, at one end 3a of the rotary shaft 3,
A conical hole 3c, a chamfered portion 3d and an end face portion 3e connecting both portions 3c and 3d are formed. In addition, the magnet holder 9 includes a fall prevention portion 9a for preventing the rotor 2 from coming off.
Is provided. The drop-out preventing portion 9a is formed so that a part thereof covers the chamfered portion 3d and the end surface facing the side plate 5 is flush with the end surface portion 3e of the rotary shaft 3.

A metal bearing ball 10 is placed in the conical hole 3c of the rotary shaft 3. Then, the ball 10 is sandwiched between the ball 10 and the pressurizing spring portion 6 of the side plate 5 to form a thrust bearing having a pivot bearing structure.

The side plate 5 is composed of a flat plate-shaped metal member fixed to one end surface of the stator 1. Then, as shown in FIG. 2, a U-shaped notch 5 is formed at the center thereof.
a is formed, and the tongue-shaped remaining portion serves as the pressurizing spring portion 6. Further, a protrusion 11 is formed on the side plate 5 so as to face the end surface portion 3e of the rotary shaft 3 and the dropout prevention portion 9a, and the thrust play of the rotor 2 is regulated.

Next, the operation of the small stepping motor configured as described above will be described.

When the electric power is supplied to the stator 1, the rotor 2 arranged in the center of the stator 1 rotates. Then, the rotary shaft 3 rotates, and the lead screw 4 formed on the rotary shaft 3 rotates.
Also rotates. By this rotation, the magnetic head holding member 13 such as the magnetic recording device engaged with the lead screw 4 is linearly driven. During the rotation of the rotor 2, the rotary shaft 3
One end 3a thereof is supported by the pressurizing spring portion 6 of the side plate 5, and the other end 3b thereof is supported by the frame 7.

In normal operation, the protrusion 1 of the side plate 5
The end face portion 3e of the rotary shaft 3 or the drop-out preventing portion 9a does not come into contact with 1. However, various forces are applied to the rotor 2 due to a load being applied to the magnetic head holding member 13 such as a magnetic recording device engaged with the lead screw 4 or the posture of a device to which the small stepping motor is attached changing. In this case, the rotor 2 causes radial runout as indicated by arrow A and rattle in the thrust direction as indicated by arrow B. Also, such radial runout and thrust play,
It also occurs during transportation of equipment to which the motor is attached.

Here, when the radial runout and the thrust backlash occur at the same time, conventionally, the place facing the protrusion 11 is the end face portion 3e of the rotary shaft 3, which is a narrow place.
The rotating shaft 3 may penetrate the side plate 5. However, in this embodiment, the place opposite to the protrusion 11 is provided with the fall prevention portion 9a of the magnet holder 9 in addition to the end surface portion 3e of the rotary shaft 3, and the facing area is expanded from 5 times to 10 times that of the conventional case. are doing. Therefore, even if the radial runout increases, the rotation shaft 3 does not penetrate through the side plate 5 because the protrusion 11 faces the drop-out preventing portion 9a. As a result, the small stepping motor operates smoothly without failure even if there are various loads and posture changes.

In this embodiment, when the rotary shaft 3 and the magnet 8 are integrated by insert molding, the fall prevention portion 9a of the magnet holder 9 covers the chamfered portion 3d of the rotary shaft 3. Axis 3 and magnet holder 9
Has improved adhesion. Further, since the drop-out preventing portion 9a is formed in the magnet holder 9, the magnet holder 9 also serves as the drop-out prevention of the rotor, and no extra member is required.

The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the detachment prevention portion 9a is integrally formed on the resin magnet holder 9, and the magnet holder 9 also serves to prevent the detachment of the rotor 2. However, as shown in FIG. Flange 3 on itself
It is also possible to provide f to serve as the fall prevention portion 3g. Further, as shown in FIG. 5, the washer 12 is inserted into the end face of the conventional rotor 23, that is, the washer 12 is fitted so as to be flush with the end face 3e of the rotating shaft 3, or the magnet of the rotor 2 is attached as shown in FIG. The magnet 8 may be designed so as to wrap around so as to be flush with the end surface 3e of the rotary shaft 3, and the magnet 8 may have a function of preventing the magnet 8 from falling off. Further, as shown in FIG. 7, the end faces of the magnet 8 and the magnet holder 9 are formed so as to be flush with the end face portion 3e of the rotary shaft 3, so that both members of the magnet 8 and the magnet holder 9 serve to prevent them from coming off. You may have it.

Further, as the protrusion 11, as shown in FIG.
The portion 11a facing the rotor 2 may be formed into a flat surface or a parallel protruding surface so as to have a slight elasticity. With this configuration, when the drop-out preventing portion is made of a soft material such as resin, the protrusion 11 does not scrape the drop-out preventing portion, and the shavings do not adversely affect the rotation operation of the motor. . Further, as shown in FIG. 9, a protrusion 14 is provided on the base side of the pressurizing spring portion 6, and the protrusion 11
It is also possible to regulate the thrust of the rotor 2 in cooperation with. The position of the protrusion 14 is such that the rotor 2 swings in the radial direction,
It is preferable that the end surface of the rotor 2 faces the protrusion 14 at a position where it is likely to come off from the protrusion 11.
By doing so, it becomes possible to further prevent the falling.
Further, since the protrusion 14 is installed at the base of the pressurizing spring portion 6, the spring elasticity can be made uniform from the base to the tip.

Further, although the present embodiment has been mainly described by taking the case of application to a small stepping motor as an example, the present invention supports the stator, the rotor, and the rotor by urging the rotor in the thrust direction with a pressurizing spring. The present invention can be applied to all small motors having a side plate that operates.

[0023]

As is apparent from the above description, in the small motor according to the first aspect of the present invention, even if the rotor swings largely in the radial direction, the fall prevention portion of the rotor maintains the state in which it faces the protrusion. Even if thrust is generated in the rotor in this state, the dropout prevention part hits the protrusion, the movement of the rotor to the side plate side is blocked, and the rotating shaft does not penetrate the side plate. The shake can be suppressed over a wide range. Moreover,
Since the area facing the projections is increased by adding the drop-out prevention portion, it is not necessary to set the projections for controlling the thrust back with high accuracy. Further, when the other end of the rotary shaft is disengaged from the frame or the like, or when the other end is bearing by the pivot bearing, it does not ride on the pivot bearing.

In addition, in the invention of claim 2, in the small motor according to claim 1, the rotary shaft and the magnet are integrated by a magnet holder to form a rotor, and the magnet holder is provided with a fall prevention portion. Therefore, the magnet holder also serves to prevent the rotor from coming off.
Therefore, it is possible to form the drop-out preventing portion without adding extra members and steps.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a plan view seen from the X direction in FIG.

FIG. 3 is a sectional view of a small stepping motor according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts of a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts of a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of essential parts of a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of essential parts of a fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view of essential parts of a sixth embodiment of the present invention.

9A and 9B are views for explaining a seventh embodiment of the present invention, in which FIG. 9A is a sectional view of a main part thereof, and FIG. 9B is a plan view seen from the Y direction of FIG. 9A.

FIG. 10 is a sectional view of a main part of a conventional small motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Rotor 3 Rotating shaft 5 Side plate 6 Pressurizing spring part 8 Magnet 9 Magnet holder 9a Fall-out prevention part 11 Protrusion

Claims (2)

[Claims] 1. A small motor having a stator, a rotor, and a side plate for biasing and supporting the rotor in a thrust direction by a pressurizing spring portion, wherein the side plate has a rotation shaft of the rotor in the thrust direction. A pressurizing spring portion that urges and supports the rotor and a protrusion for restricting thrust play of the rotor, and is formed radially outward of the rotary shaft at an end surface of the rotor that faces the side plate. A small motor characterized in that a drop-out preventing portion is formed to prevent the rotary shaft from coming off from the protrusion. 2. The small motor according to claim 1, wherein the rotor is configured by integrating the rotating shaft and a magnet by a magnet holder, and the drop-preventing portion is formed in the magnet holder.