JP3713126B2 - Small motor shaft support structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a shaft support structure of a small motor, and more particularly to a reduction in shaft support loss and an improved oil holding effect.
[0002]
[Prior art]
Conventionally, as a shaft support structure for a small motor, there is a type using a so-called hollow oil-impregnated bearing in which a bearing side is made a middle escape in order to reduce a shaft support loss.
[0003]
[Problems to be solved by the invention]
However, such a conventional hollow oil-impregnated bearing is difficult to manufacture, and cost increase cannot be avoided.
In addition, since a hollow oil-impregnated bearing requires the thickness of the bearing itself, there is a dislike that the size must be increased in the radial direction.
[0004]
Accordingly, an object of the present invention is to solve the above problems with a simple structure to reduce the bearing loss, and to prevent the outflow by increasing the oil retaining effect at the bearing part, thereby extending the service life. It is intended to provide a shaft support structure for a small motor that is realized and does not sacrifice the radial size.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention can be achieved by reducing the shaft bearing loss on the shaft side of the shaft bearing portion and enhancing the oil retaining effect at the shaft bearing portion.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
As an embodiment of the present invention, as shown in claim 1, in the shaft support structure of a small motor in which either one of the shaft and the bearing is rotatable relative to the other as a sintered oil-impregnated bearing, What is necessary is just to provide the means which increases a surface area while reducing a rotation support area in the shaft side of a shaft support part.
[0007]
Specifically, as a means for reducing the rotation support area and increasing the surface area on the shaft side of the shaft support portion, as shown in claim 2, the shaft is rotatably supported at both ends of the bearing and the diameter between them is reduced, In addition, it is preferable to form a plurality of grooves in the small diameter portion or to form irregularities in the small diameter portion as shown in claim 3. If it does in this way, a bearing loss can be reduced and the oil retention effect can be heightened.
[0008]
【Example】
Next, as a first embodiment of the shaft support structure for a small motor according to the present invention, a structure of a shaft rotation type will be described with reference to a longitudinal sectional view of an essential part shown in FIG.
In the figure, reference numeral 1 denotes a stator base in which a bearing holder 2 is fixed by means such as caulking, and a relatively long sleeve-type sintered oil-impregnated bearing 3 is mounted inside the bearing holder 2 by means such as press fitting. ing. Reference numeral 4 denotes a shaft, which is a feature of the present invention. The rotary bearings 4a and 4a are applied to both ends of the sintered oil-impregnated bearing 3, the small-diameter portion 4b disposed between them, and the five grooves 4c provided in the radial direction. Is formed. The base end of this shaft is rounded, and is pivotally supported by a receiving plate 2a crimped to the bearing holder 2 via a contact plate 2b.
Therefore, since the shaft support structure configured in this way can obtain the same effect as the hollow bearing by the rotary support portions applied to both ends of the sintered oil-impregnated bearing 3, the shaft support loss can be reduced, and the five grooves provided in the ring are provided. Since the surface area is increased, the oil retention effect can be enhanced.
As a structure using such a shaft support structure for a small brushless motor, there is a structure as shown in a longitudinal sectional view of an essential part of FIG. That is, a core 5 in which a plurality of thin plates such as silicon steel plates are laminated is fixed to the outer peripheral surface of the bearing holder 2, and a plurality of coils 6 are formed on the core 5 by windings. A rotor yoke 7 formed in a cup shape is fixed to the shaft 4, and a ring-shaped field magnet 8 is arranged on the inner peripheral surface of the rotor yoke 7 so as to face the core 5 through a predetermined gap. The rotor R is configured.
[0009]
FIG. 3 is a longitudinal sectional view of an essential part showing the structure of a fixed shaft type as a second embodiment of the shaft support structure of the small motor of the present invention.
In the figure, the stator base 11 has a shaft holder 22 raised by a burring in the center, and is held by press-fitting a shaft 44 similar to the above into the shaft holder 22. The stator base 11 is press-fitted into the rotor yoke 77. A sleeve type sintered oil-impregnated bearing 3 is rotatably mounted. In the figure, 4d is an E-ring for retaining, and 4e is two thrust washers formed by punching a polyester sheet. Further, the rotation support portion, the small diameter portion, and the plurality of grooves provided in the radial direction are the same as those in the above embodiment, so the same reference numerals are given and the description thereof is omitted.
[0010]
FIG. 4 is a longitudinal sectional view of an essential part of a shaft support structure in which irregularities are formed in a small diameter portion as means for increasing the surface area as a modification of these embodiments.
As a means for forming the unevenness 9, a satin finish by sandblasting or fine knurling can be employed.
[0011]
Needless to say, the shaft support structure of FIG. 4 can also be configured as a fixed shaft type.
[0012]
【The invention's effect】
Since the shaft support structure of the present invention is configured as described above, the same effect as that of the hollow bearing can be obtained by the rotation support portions applied to both ends of the sintered oil-impregnated bearing 3, and the shaft support loss can be reduced. Since the surface area is increased by the individual grooves and irregularities, the oil retention effect can be enhanced, so that the oil can be prevented from flowing out and the life can be extended. Moreover, since the shaft is machined, the radial size is not sacrificed, and the cost is advantageous.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part of a first embodiment of a shaft support structure for a small motor according to the present invention.
2 is a longitudinal sectional view of a main part of a small brushless motor using the shaft support structure of FIG. 1. FIG.
FIG. 3 is a longitudinal sectional view of an essential part of a second embodiment of the shaft support structure for a small motor according to the present invention.
[Fig. 4]
[Explanation of symbols]
1, 11 ... Stator base 2 ... Bearing holder 3 ... Sleeve type sintered oil-impregnated bearing 4 ... Shaft 4a ... Rotating bearing 4b ... Small diameter part 4c ... Groove 9 ... Concavity and convexity 22 ... Shaft holder

Claims (2)

In a small motor shaft support structure in which a bearing is a sintered oil-impregnated bearing and the shaft and the bearing are relatively rotatable, the bearing is a cylindrical bearing formed with a predetermined inner diameter, and the shaft includes both ends of the bearing. A small-sized motor comprising a bearing portion that is rotatably supported on a side and a small-diameter portion provided between the rotational-supporting portions, and a plurality of circumferentially continuous grooves formed in the small-diameter portion . Shaft support structure. In a small motor shaft bearing structure in which the bearing is a sintered oil-impregnated bearing and the shaft and the bearing are relatively rotatable, the bearing is a cylindrical bearing formed with a predetermined inner diameter, and the shaft is on both ends of the bearing. A shaft support structure for a small motor, characterized in that it comprises a bearing portion that is rotationally supported by and a small-diameter portion provided between the rotational bearing portions, and a plurality of uneven irregularities are formed in the small-diameter portion .

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