JP2003235200A - Small motor and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce thrust noise and to secure axial perpendicularity with precision by setting the end play to an optimum value. <P>SOLUTION: A bearing 3 having an outside diameter smaller than the inside diameter of a bearing support part is housed in the bearing support part with a gap in between. The state in which axial perpendicularity is kept is generated for a one-body motor with the bottom surface of a motor case as a reference, which is held. A bearing support outer peripheral surface is pressed with three or more tapered tools 22 from the outside in the radial direction whose center is a motor shaft, in the middle of the bearing in the thrust direction of the motor in which the axial perpendicularity is maintained. Thus, a protrusion is formed on the inner peripheral surface of the bearing support part while a recess is simultaneously formed on the outer peripheral surface of the bearing corresponding to it, to deform the bearing support part to secure the bearing 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor for holding and fixing a right angle of a motor shaft to a motor case mounting end surface of a small motor used for audio / visual equipment and the like, and a manufacturing method thereof. Is.

[0002]

2. Description of the Related Art In a conventional small motor, a shaft of a completed rotor is inserted into the center of a bottom of a hollow cylindrical metal motor case, and then a case lid is fitted into the opening of the motor case. It is assembled by tightening. The rotor is rotatably supported by two bearings that are press-fitted and fixed to the bottom center of the motor case and the center of the case lid, respectively.

If the two bearings are not on the coaxial line, the shaft 4 is inclined with respect to the bottom surface of the motor case 1, as shown in FIG. Note that the configurations of the core, the windings, the commutator, and the like are omitted for the sake of easy understanding. Normally, the bottom surface of the motor case 1 is fixedly attached to the equipment used with the shaft 4 at a right angle. The perpendicularity between the bottom surface of the motor case and the shaft 4 is referred to as the "axis perpendicularity". That said, there are motors whose standards are defined. Conventionally, in order to finish the axis perpendicularity within a predetermined range, the accuracy of each part has been increased. The motor case 1 improves the accuracy of the coaxiality between the opening of the case alone and the bearing support inner diameter, while the case cover 7
After press-fitting the bearing 8, the outer periphery of the case lid 7 is trimmed to improve the accuracy.

The end play (movement allowance in the thrust direction of the motor shaft, gap) is the bearing press-fitting depth of the motor case, the bearing press-fitting depth of the case lid, and the bush from the shaft end on the case lid side (to position the rotor in the axial direction). (Made of resin or metal provided on the shaft)
The size of the rotor at the end is controlled so that the end break standard is met when each is incorporated. Therefore, an adjustment washer having a suitable thickness is selected from among various types of adjustment washers having different thicknesses and incorporated between the bush and the bearing.

Increasing the precision of each component in order to obtain the perpendicularity of the axis leads to an increase in cost. First, since it is necessary to improve the accuracy of the mold, the cost of the mold is high, and in order to maintain the accuracy, the frequency of exchanging consumables such as punches of the mold becomes high. Along with that, many mold maintenance personnel are required. Satisfaction of process capability (capability of producing a product of what level of quality) is
As the precision increases, it becomes difficult and the defect rate tends to increase. If the process capability is not satisfied, the dimensional inspection cannot be eliminated. The outer peripheral trimming, which is performed to improve the accuracy of the case lid, is much less productive than the standard process in which only normal bearing press fitting is performed.

Mechanical noise is often caused by a large clearance between the bearing and the shaft, causing the inner diameter of the bearing and the shaft to collide with each other. There is a measure to reduce the inner diameter of the bearing as a method of reducing the mechanical noise, but if the coaxiality of both bearings is not good, the shaft is likely to rub and the inner diameter of the bearing cannot be reduced, and it is difficult to reduce the mechanical noise.

In order to use the adjustment washer for making the end play constant, it is necessary to prepare various types of washers having different thicknesses. Further, a step of measuring the rotor dimensions and an end play preliminary dimension inspection step before caulking the motor case and the case lid are required.

Further, the present applicant has previously proposed a technique that restricts the movement of the bearing in the thrust direction to reduce the end play and does not necessarily require an adjustment washer (see Japanese Patent Laid-Open No. 2000-350401). ). A bearing constructed based on this technique is shown in FIG. 8 and its manufacturing method is shown in FIG. As shown, in the bearing support 2 formed integrally with the motor case (not shown),
The bearing 3 is accommodated. Reference numeral 5 denotes a part of the bush supported by the bearing 3 in the thrust direction.

The illustrated bearing 3 is inserted with a gap between the outer peripheral surface of the bearing 3 and the inner peripheral surface of the bearing support 2, and then a protrusion is formed on the inner peripheral surface of the bearing support 2. A corresponding concave portion is formed on the outer peripheral surface of the bearing 3 along the line on the circumference,
It is formed continuously or discontinuously, whereby the bearing 3 is fixed inside the bearing support 2.

In order to do this, as shown in FIG. 9, the bearing support portion 2 is formed by using a pressing jig shown in the figure in a state where a constant force is applied to the bearing 3 from the outside in the thrust direction of the motor. Is pressed from the outside in the radial direction along a circumferential line centered on the axis of the shaft 4. At the time of this pressing, a roller (not shown) having a predetermined axial length for supporting the bearing support portion 2 from the side opposite to the pressing direction of the pressing jig.
Is used.

With such a technique, it is possible to obtain a very small end play without using an adjustment washer, and it is possible to reduce thrust noise. In addition, although the bearing is restricted from moving in the thrust direction,
Since it can be tilted, even if the squareness of the bearing and the bush with respect to the motor shaft is slightly deviated, the rotor does not bounce and noise is not generated. However, this technique is not aimed at finishing the perpendicularity of the axis itself between the bottom surface of the motor case and the shaft with high accuracy.

Further, as described above, since it is necessary to support the bearing support portion 2 by using a roller from the side opposite to the pressing direction by the pressing jig, the outer diameter of the bearing support portion is restricted, It cannot be used for small outer diameters. In addition, the bearing support height (axial length) is also limited by the relationship between the need to crimp the center of the bearing and the blade thickness that maintains strength.

[0013]

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned problems and enables application to a bearing support portion having a smaller outer diameter and height, and end play is achieved. The object of the present invention is to provide a small motor that can be set to an optimum value to reduce thrust noise as well as ensure a highly accurate shaft perpendicularity.

Another object of the present invention is to reduce the cost by eliminating the need to increase the precision of each component in order to secure a highly accurate axis perpendicularity.

[0015]

The small motor of the present invention comprises:
An integrally formed bearing support portion formed by projecting in a cylindrical shape is formed on the bottom surface of the motor case having an opening, and a bearing supported in the bearing support portion and a case lid fitted into the opening portion of the motor case. The shaft of the rotor is rotatably supported by both the bearing and the bearing provided in the central portion. The bearing supported in the bearing support portion has a substantially cylindrical shape having a through hole for inserting the shaft in the center, and has an outer diameter smaller than the inner diameter of the bearing support portion before deformation, It is accommodated in the bearing support portion with a gap provided therebetween. The bearing support part of the integrally assembled motor is a circumferential line centered on the motor shaft at the center of the bearing in the thrust direction with the perpendicularity of the shaft maintained with respect to the bottom surface of the motor case. Along the radial direction from the outer side to the outer peripheral surface 3
By pressing more than a point to form a protrusion on the inner peripheral surface of the bearing support and a corresponding recess on the outer peripheral surface of the bearing at the same time, the bearing support is pressed from its outer peripheral side to be deformed to form the bearing. It is fixed.

Further, the manufacturing method of the small motor of the present invention is as follows.
A bearing having a substantially cylindrical shape having a through hole for inserting a shaft in the center and having an outer diameter smaller than the inner diameter of the bearing support is accommodated in the bearing support with a gap provided therebetween. After assembling the individual parts including the motor case that accommodates the bearings as a small motor together, create a state in which the perpendicularity of the shaft is maintained with this assembled motor as the reference, and change this state. Hold. For a motor in which this axis perpendicularity is maintained,
At approximately the center of the bearing in the thrust direction, 3 from the outside in the radial direction along the circumferential line centered on the motor shaft.
By pressing the outer peripheral surface of the bearing support portion with a tool having at least one thin tip, a projection is formed on the inner peripheral surface of the bearing support portion and a corresponding concave portion is formed on the outer peripheral surface of the bearing at the same time. The part is pressed from its outer peripheral side to deform,
Fix the bearing.

[0017]

1 is a schematic vertical cross-sectional view of a small motor to which the present invention is applied, and FIG. In the figure, reference numeral 1 denotes a metal case having a hollow cylindrical shape with a bottom. A magnet 10 serving as a stator magnetic pole is fixed to the inner peripheral surface of the motor case, and a bearing 3 is housed in the bottom center of the motor case 1. In order to do so, a cylindrical protrusion, that is, the bearing support 2, is integrally provided. A metal case cover 7 is fitted into the opening of the motor case 1. In the case lid 7, a support portion for accommodating a bearing 8 and a shaft receiver 9 which are press-fitted and fixed is provided in the center portion of the case lid 7.
It is provided integrally with. A brush 11 and a terminal connected to the brush 11 are attached to the case lid 7 via a resin holder. A rotor is constructed by mounting the core, the windings, and the commutator 12 on the shaft 4. In the figure, 5 is
It is a resin or metal bush that positions the rotor in the axial direction. The configuration described above is normal except for the bearing 3 and the configuration related thereto.

The structure of the bearing 3 which characterizes the present invention is shown in FIG.
It will be described with reference to FIG. 2 showing the details of the portion A shown in FIG. In FIG. 2, a sintered alloy bearing 3 is housed integrally with a metal motor case 1 in a cylindrical bearing support portion 2 formed in the central portion of the bottom surface thereof. As shown in the drawing, the bearing 3 has a substantially cylindrical shape having a through hole for inserting a shaft in the center, and has an outer diameter smaller than the inner diameter of the bearing support portion 2 before deformation, It is accommodated in the bearing support portion with a gap provided therebetween. Then, while the concave portion 32 is formed on the outer surface of the cylindrical bearing support portion 2, the protrusion portion 31 is formed on the inner surface corresponding to the position.
Further, in response to the formation of the protrusion 31, the bearing 3
A recess is formed in the. Reference numeral 5 denotes a part of the bush supported by the bearing 3 in the thrust direction. The bush 5 (5 'is a collar of the bush) is a normal one in itself, and is press-fitted and fixed onto the shaft 4. Further, the adjustment washer 6 is provided between the bush 5 and the bearing 3 if necessary, although not essential in the present invention. The bearing 3 supports the shaft 4 in the thrust direction by a bush 5 (and an adjustment washer 6 if necessary). The present invention does not require a washer for adjusting the end play, but an oil stop washer for preventing the oil filled in the pores of the sintered alloy bearing from flowing out. Alternatively, a thrust washer intended to prevent direct contact between the bush and the bearing can be used. However, these washers do not need to adjust the thickness or the number of sheets, and thus do not cause a cost increase as much as the adjustment washers.

FIG. 4 is a view for explaining a method of positioning and fixing the bearing 3 which is a feature of the present invention in the bearing support portion. A clearance is provided between the inner diameter of the bearing support portion 2 of the motor case 1 and the outer diameter of the bearing 3 (for example, 20
〜40μm), assemble the motor. That is, the bearing 3 is arranged at the center of the bottom of the motor case to which a magnet (not shown) is fixed, and the shaft 4 of the completed rotor is provided on the bearing 3 (cores other than the shaft, windings, commutators, etc. are not shown). After inserting, the case lid 7 is fitted into the opening of the motor case 1.

The motor assembled in this way is
With the case lid side bearing 8 as a reference, both bearings 3 and 8 are made coaxial, and a state is maintained in which the perpendicularity of the axis is maintained with respect to the bottom surface of the motor case 1, and this state is maintained.
For example, as shown in the figure, while positioning the assembled motors on the tools 22 arranged side by side,
The outer diameter portion of the motor case 1 is clamped from two opposite directions by two V blocks 23 (blocks each having a V shape as a whole, which enables positioning of the motor case in a recess formed in the center). At the same time, the shaft 4 can be fixed by the collet chuck 21 or the like. As described above, since the clearance is provided between the inner diameter of the bearing support portion 2 and the outer diameter of the bearing 3, it is possible to fix the motor case 1 and the shaft 4 while maintaining the perpendicularity of the shaft. Has become.

While maintaining this state in which the squareness is maintained, the bearing support portion 2 is pressed from its outer peripheral side to be deformed by using a plurality of tools 22 (blades) having thin tips (see FIG. 5), Fix the bearing. 5A and 5B are views for explaining the pressing deformation by the tool 22, in which FIG. 5A is a cross-sectional view showing the shaft arranged laterally, and FIG. 5B is in the direction of the bearing 3 from the tip end side of the shaft. It is the figure seen. At this time, it is preferable that the axial position of the tool 22 is caulked near the center of the bearing 3 in the thrust direction. The reason is that the moving resistance of the bearing 3 is maximized. In order to prevent the bearing support portion 2 from being distorted, the tip of each tool 22 is preferably thin. In the illustrated example, twelve tools radially arranged with respect to the shaft are used, but any number of tools of three or more can be used, and preferably 8 to 8 for securing bearing movement resistance. 14 tools can be used.

6 and 7 are views for explaining a method of positioning and fixing the bearing 3 in the bearing support portion while ensuring an end play of a predetermined length. After assembling the motor by providing a clearance between the inner diameter of the bearing support portion of the motor case and the outer diameter of the bearing, in the illustrated example, in order to secure an end play of a predetermined length, the bearing 3 is supported from the outside in the axial direction (see FIG. 6). (From bottom to top). As shown in FIG. 6, this load causes the motor case side bearing 3 to hit the bush 5 (directly or indirectly via the adjustment washer), and the case lid side shaft end to hit the shaft receiver 9. Hang up to. For example, in order to prevent the motor from moving due to the axial load from the outside, hold the motor from the case lid side with a force that does not lose the load, and use the collet chuck (upward in the figure) to load the motor. Can be multiplied. From the state where the load is applied and the load is abutted, the rotor and the bearing 3 are then moved in a direction opposite to the direction in which the load is slightly applied for a predetermined length (downward in the drawing). This movement is performed by, for example, the shaft 4
Can be performed by the collet chuck 21 holding the. At this time, it is performed so that there is no gap between the bearing 3 and the bush 5.

FIG. 7 shows the state after the movement.
At this time, a gap corresponding to the movement of the rotor is formed between the shaft receiver 9 and the case lid side shaft end. In this state, as described above with reference to FIG.
2 is used to deform the bearing support portion 2 to fix the bearing 3. As a result, the above gap is maintained even after the motor assembly is completed, and this gap corresponds to an end play of a predetermined length.

[0024]

According to the present invention, a clearance is provided between the inner diameter of the bearing support portion and the outer diameter of the bearing, and the bearing is fixed in a state where the perpendicularity of the axis is out. It is possible to assemble a motor that secures the angle. Since the gap between the coaxial axes is absorbed by the clearance between the bearing support inner diameter and the bearing outer diameter, it is not necessary to improve the precision of each component. If the tolerance of the coaxiality between the opening and the inner diameter of the bearing support portion in the motor case alone is widened, a highly accurate mold becomes unnecessary, and running costs such as consumables and maintenance costs can be suppressed. If the tolerance of parts accuracy becomes wider, the stroke capability, which shows the ability of producing a product of what level of quality, becomes better, and it becomes possible to eliminate inspection. It is possible to eliminate the trimming of the outer diameter of the case lid to improve accuracy, and standardize the process by simply press-fitting and fixing the bearing to the case lid plate, thus reducing equipment costs and management costs.

The present invention also has the effect of reducing mechanical noise because the clearance between the inner diameter of the bearing and the outer circumference of the shaft can be reduced. Even in the axial clearance, the end play can be kept constant without selecting an adjustment washer, so the washers with the same thickness 1
It is possible to use only one or none at all. Accordingly, the rotor dimension measurement step, the end play preliminary dimension inspection step, etc. can be deleted.

Further, the present invention can also be applied to a motor having a bearing support portion having a small height and outer diameter, which has hitherto been impossible.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a small motor to which the present invention is applied.

FIG. 2 is a diagram showing details of a portion A shown in FIG.

FIG. 3 is a diagram for explaining a problem of the conventional technique in which the shaft is inclined with respect to the bottom surface of the motor case.

FIG. 4 is a diagram for explaining a method of positioning and fixing a bearing, which is a feature of the present invention, in a bearing support portion.

5A and 5B are views for explaining a pressing deformation by a tool, FIG. 5A is a cross-sectional view showing a shaft arranged laterally, and FIG. 5B is a view seen from a tip end side of the shaft toward a bearing 3. It is a figure.

FIG. 6 shows the bearing 3 while ensuring an end play of a predetermined length.
It is a figure for demonstrating the method of positioning and fixing in a bearing support part.

FIG. 7 is a diagram showing a state after moving from the state shown in FIG.

FIG. 8 is a diagram showing a bearing configuration previously proposed by the applicant.

9 is a diagram for explaining a method of manufacturing the bearing shown in FIG.

[Explanation of symbols]

1 motor case 2 Bearing support 3 bearings 4 shafts 5 bush 6 Adjustment washers 7 Case lid 8 bearings 9 Shaft support 10 magnets 11 brushes 12 committers 21 Collet chuck 22 tools 23 V block 31 Projection 32 recess

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H605 BB05 BB09 CC03 CC04 CC10                       EB01 EB16 GG03 GG04                 5H615 AA01 BB01 BB04 BB14 PP25                       PP28 SS04 SS09 SS10 SS19

Claims (4)

[Claims] 1. A motor case having an opening is provided with a bearing support portion integrally formed on the bottom surface of the motor case, the bearing support portion being supported in the bearing support portion and the opening portion of the motor case. In a small-sized motor that rotatably supports the shaft of the rotor by means of both bearings provided in the central portion of the case lid, the bearing supported in the bearing support portion has a through hole for inserting the shaft in the center. The bearing support portion has a substantially cylindrical shape having a hole, and has an outer diameter smaller than the inner diameter of the bearing support portion before deformation, and is accommodated in the bearing support portion with a gap therebetween. With the motor assembled in step 1, the axial perpendicularity with respect to the bottom surface of the motor case is maintained, and the radial direction along the circumferential line centered on the motor shaft is approximately at the center of the bearing in the thrust direction. From the side, the outer peripheral surface of the bearing support portion is pressed at three or more places to simultaneously form a protrusion on the inner peripheral surface of the bearing support portion and correspondingly form a recess on the outer peripheral surface of the bearing, and to deform the bearing support portion. , A small motor with fixed bearings. 2. The small motor according to claim 1, wherein the bearing support has the motor case side bearing fixed with a slight distance corresponding to end play between the case lid side shaft end and the shaft receiver. . 3. A motor case having an opening is provided with a bearing support portion integrally formed on the bottom surface of the motor case, the bearing support portion being supported in the bearing support portion and the opening portion of the motor case. In a method of manufacturing a small motor in which a rotor shaft is rotatably supported by a bearing and a bearing provided in a central portion of a case lid, a substantially cylindrical shape having a through hole for inserting the shaft in the center is provided. In addition, a bearing having an outer diameter smaller than the inner diameter of the bearing support portion is housed in the bearing support portion with a gap therebetween, and the individual parts including the motor case accommodating the bearing are integrally assembled as a small motor. After this, the assembled motor is maintained in this state by creating a state where the axis perpendicularity is maintained with reference to the bottom surface of the motor case. At the center of the bearing in the thrust direction, the outer peripheral surface of the bearing support portion is pressed by a tool having three or more thinned tips from the outside in the radial direction along the circumferential line centering on the motor shaft. A projection is formed on the inner peripheral surface of the bearing support portion, and a corresponding recess is formed on the outer peripheral surface of the bearing, and the bearing support portion is thereby deformed to fix the bearing. Manufacturing method of small motor. 4. The motor case side bearing is mounted on the shaft before the step of fixing the bearing by pressing the bearing support portion from the outer peripheral side to deform the motor in a state where the axial perpendicularity is maintained. Apply a load until it hits the bush of directly or indirectly and the shaft end on the case lid side hits the shaft receiver, then end play the rotor and motor case side bearings in the direction opposite to the direction in which this load is applied. The method for manufacturing a small motor according to claim 3, further comprising a step of moving the motor by a small distance corresponding to.