JP2001157407A - Small-sized motor provided with helicoidal pre-load adjusting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life small-sized motor provided with a ball bearing which is free from axial runouts even during high-speed revolution, and produces low noise and no resonance. SOLUTION: A small-sized motor is formed by placing a bearing comprising a ball bearing to which pre-load can be applied in a bearing housing 2 embedded in a stator base 1. The small-sized motor is provided below the bearing housing 2 with a pre-load adjusting mechanism that is slid by a helicoidal scheme (bearing housing 2 and bottom plate 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 having a ball bearing, and more particularly, to a small motor having a long life, low noise, and no shaft runout.

[0002]

2. Description of the Related Art Conventionally, a small motor using a sintered oil-impregnated metal as a bearing has been proposed. However, in such a conventional bearing device using a sintered oil-impregnated metal, when the rotor (rotating shaft) is rotated at a high speed, the bearing portion is severely worn, and the life of the bearing is short. There were disadvantages. Accordingly, various small cored motors having rolling bearings have been proposed. For example, there is a type in which a bearing filled with a ball is fixed between an inner ring and an outer ring by a case, a base, and a bearing housing, and the rotating shaft is supported by the ball bearing. When such a rolling bearing is used, a method of preloading the ball is used to absorb backlash in the bearing part.However, the following disadvantages occur when used at high speed rotation both at fixed position preload and constant pressure preload. was there.

[0003]

According to the fixed position preloading method, the ball is preloaded by biasing the inner ring or the outer ring in the axial direction. However, in this method, a small gap is always required for assembling. It was a play when needed. Due to the backlash, shaft run-out occurs as the number of revolutions increases, and the noise increases accordingly. Further, according to the method of constant pressure preload, the ball is preloaded by energizing with a coil spring or a disc spring in the axial direction, but this method causes a resonance phenomenon as the rotational speed increases, and impairs the function as a motor. And the like.

Accordingly, an object of the present invention is to solve the above-mentioned problems and realize a small-size ball bearing having a long life without resonance while achieving no shaft vibration even at high speed rotation. It is intended to provide a motor.

[0005]

In order to solve the above-mentioned problems, a bearing comprising a preloadable ball bearing is provided inside a bearing housing implanted in a stator base as in the first aspect of the present invention. This can be achieved by providing a preload adjusting mechanism that slides in a helicoid manner below the bearing housing in a small motor provided. Also,
As in the invention according to claim 2, the helicoid type preload adjusting mechanism cuts an internal thread on the inner periphery of the bearing housing,
This can be achieved by adjusting the outer circumference of the bottom plate with external threads. The above-mentioned ball holder can be achieved by providing at least one ball holder slidably in the axial direction. Further, as in the third aspect of the present invention, the helicoid type preload adjusting mechanism can be achieved by cutting a male screw on the outer periphery of the bearing housing and cutting a female screw on the bottom plate for adjustment.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a second embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a stator base, and a reference numeral 2 denotes a substantially cylindrical bearing housing implanted in the stator base 1, and a bottom plate 3 is mounted near the bottom so as to be adjustable by screwing. That is, it is a helicoid type preload adjusting mechanism arranged near the lower part of the bearing housing. Reference numeral 4 denotes a thrust bearing provided at the center of the upper surface of the bottom plate 3. Reference numeral 5 denotes a shaft whose one end is axially regulated by the thrust bearing 4, and reference numeral 6 denotes a central short cylindrical shaft fixing portion 6a.
This is an inverted cup-shaped rotor case fixed to the shaft 5 by a shaft. Reference numeral 7 denotes a ring magnet fixed to the inner periphery of the rotor case 6. The ring magnet 7 and the rotor case 6 constitute a rotor R. Reference numeral 8 denotes a stator core fixed to the outer periphery of the bearing housing 2, and reference numeral 9 denotes a coil wound around the stator core 8. Reference numeral 10 is slidably fitted along the inner periphery of the bearing housing 2, a free end side of the upper surface is formed in a mortar-shaped taper 10 a toward the center, and the lower surface is slidably held by the bottom plate 3. You. Numeral 11 denotes balls held at equal intervals by a retainer 12, which are rotatably arranged on the taper 10a. Numeral 13 is slidably fitted along the inner periphery of the bearing housing 2, and tapered 13a, 13b is formed in a mortar shape at the upper and lower ends of the upper surface toward the center, each holding a ball. The lower end 14 has a mortar-shaped taper 14a toward the center on the free end side of the lower surface, and the upper end is fitted near the upper end of the bearing housing 2. 15 is retainer 1
6, the taper 14a, the taper 1
It is supported at three points by 3a and shaft 5. In the first embodiment shown in FIG. 1, the helicoid-type preload adjusting mechanism disposed near the lower part of the bearing housing includes:
Although the figure shows that the bottom plate 3 is attached to the inner periphery of the bearing housing 2 by screwing, it is needless to say that a male screw may be cut outside the bearing housing 2 and a female screw may be provided on the bottom plate 3 for attachment.

In the first embodiment constructed as described above, the balls 15 are held at regular intervals by the retainer 16 and the taper 14a and the taper 13a, as described above.
The shaft 5 is supported at three points, and is positioned around the upper portion of the shaft 5 while freely rotating the outer periphery of the shaft 5. Similarly, the ball 11 is held at equal intervals by the retainer 12, and is supported at three points by the taper 10a, the taper 13b and the shaft 5, and is positioned around the lower portion of the shaft 5 while freely rotating around the shaft 5. I have. If the ball or the like has been worn for a while and the diameter has become small and the backlash has occurred, the bottom plate 3 is rotated to adjust the helicoid type preload adjusting mechanism and the movable ball holder 10 to adjust the play. Can be absorbed. As described above, since the movement in the axial direction is adjusted by the rotation method, precise adjustment can be easily performed.

Next, FIG. 2 shows a second embodiment of the present invention. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 20 denotes a biasing spacer which is slidably fitted along the inner periphery of the bearing housing 2, and the degree of sliding is adjusted by turning the bottom plate 3 clockwise or counterclockwise. Reference numeral 21 denotes an outer ring of the first ball bearing, and an annular rolling groove 21a having a diameter larger than the diameter of the ball 11 on the inner periphery.
It has. Further, since the ball 11 is urged upward by the urging spacer 20, the ball 11 is pushed upward below the rolling groove 21a. Reference numeral 22 denotes an inner ring of the first ball bearing, which is provided with an annular rolling groove 21a having a diameter larger than the diameter of the ball 11 on the outer periphery similarly to the outer ring. 23 is axis 5
Is an intermediate spacer loosely fitted on the outer periphery of the. Reference numeral 24 denotes an outer ring of the second ball bearing, which has an annular rolling groove 24a having a diameter larger than the diameter of the ball 11 on the inner periphery. Further, the outer movement of the outer ring 24 of the second ball bearing is restricted by the bearing housing 2 in the upward direction. Reference numeral 25 denotes an inner ring of the second ball bearing, which is provided with an annular rolling groove 24a having a diameter larger than the diameter of the ball 11 on the outer periphery, and its sliding is regulated by the intermediate spacer 23 on the lower side and by the upper end spacer 26 on the upper side. .

In the second embodiment thus configured, the outer ring 21 of the first ball bearing is urged upward by the urging spacer 20, whereby the ball 11 moves upward. The inner ring 22 of the first ball bearing is prevented from moving upward by the intermediate spacer 23. For this reason, the outer race 21 of the first ball bearing
In order to hold the ball 11 on the lower side of the annular rolling groove 21a and on the upper side of the annular rolling groove 22a of the inner race 22 of the first ball bearing, play is removed. Similarly, the inner ring 25 of the second ball bearing is urged upward by the intermediate spacer 23, and the ball 15 moves upward. However, the outer ring 24 of the second ball bearing is moved upward by the bearing housing 2 as described above. Movement to is regulated. For this reason, the annular rolling groove 25 of the second ball bearing inner race 25
In order to hold the ball 15 on the lower side of a and on the upper side of the annular rolling groove 24a of the outer ring 24 of the second ball bearing, play is removed.

[0011]

As described above, the present invention is provided with a preload adjusting mechanism that slides in a helicoid manner below the bearing housing, so that if the ball is used for a while and rattle occurs due to wear of the ball, the bottom plate 3 is removed. It is corrected by adjusting the screwing and preload adjusting mechanism. As described above, it is possible to provide a small-sized motor in which precise adjustment can be easily performed by adjusting the axial movement adjustment in the rotation direction by the helicoid method.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 R Rotor 1 Stator base 2 Bearing housing 3 Bottom plate 4 Thrust bearing 5 Shaft 6 Rotor case 7 Ring magnet 8 Stator core 9 Coil 10, 13 Movable ball holder 11, 15 Ball 12, 16 Retainer 14 Fixed ball holder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J012 AB04 BB01 BB03 CB01 FB10 HB02 3J017 AA05 CA07 DB01 HA10 3J101 AA02 AA43 FA41 5H605 AA05 BB05 BB19 CC04 EB10 EB37 EB39

Claims (3)

[Claims] 1. A small motor in which a bearing composed of a preloadable ball bearing is disposed inside a bearing housing implanted in a stator base, wherein a preload adjusting mechanism that slides in a helicoid system below a bearing housing. A small motor characterized by comprising: 2. The helicoid-type preload adjusting mechanism according to claim 1, wherein said helicoid-type preload adjusting mechanism is adjusted by cutting a female screw on an inner periphery of a bearing housing and cutting a male screw on an outer periphery of a bottom plate. Equipped small motor. 3. The compact helicoid type preload adjusting mechanism according to claim 1, wherein the helicoid type preload adjusting mechanism is adjusted by cutting a male screw on an outer periphery of a bearing housing and cutting a female screw on a bottom plate. motor.