JPH0543746U - Bearing device for small electric motors - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a bearing device for a small electric motor, which can stably maintain the clearance between the rotor shaft and the bearing at an appropriate value and easily adjust the centers of the bearings to coincide with each other. [Configuration] In a bearing device for a small electric motor, in which both ends of the rotor shaft 2 are rotatably supported by bearings 12 and 13 provided on the inner peripheral surfaces of the bearing bases 10 and 11, at least one of the bearing bases 10 and 11 Is formed into a cylindrical shape and a plurality of screw holes 10c are formed in the peripheral wall toward the center, and bearings 12 and 13 are provided with a plurality of protrusions 12b and 13b parallel to the axis on the outer peripheral surface thereof. The line connecting the vertices in a circle is made larger than the diameter of the inner peripheral surface of the bearing stand 10,11 and the bearing is pressed into the bearing stand so that the protrusion 12b overlaps the screw hole 10c. The bearing 12 can be aligned by screwing the push screw 16 onto the 10c.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bearing device for a small electric motor in which both ends of a rotor shaft are supported by bearings mounted on a bearing stand.

[0002]

[Prior Art]

 A bearing device for a general small-sized electric motor has a structure in which both ends of a rotor shaft are rotatably supported by roughly cylindrical bearings provided on the inner peripheral surface of the bearing base. The bearing and the bearing have, for example, the shape shown in FIG. The bearing base A is made of brass, for example, and has a thin-walled cylindrical shape with a collar Aa. The bearing B is made of, for example, a sintered alloy, and has a bearing hole Ba and has a thick-walled cylindrical shape. .. The diameter of the outer peripheral surface Bb of the bearing B is slightly larger than the diameter of the inner peripheral surface Ab of the bearing stand A, so that the bearing B is press-fitted and mounted in the bearing stand A.

[0003]

[Problems to be solved by the device]

 By the way, in the bearing device for the small electric motor described above, when the bearing B is press-fitted into the bearing base A, the bearing hole Ba is deformed small due to the variation in the press-fitting margin, especially when the press-fitting margin is large. Therefore, there is a method to deal with it by increasing the inner diameter of the bearing hole Ba in advance, but if it does so, the clearance between the rotor shaft and the bearing hole Ba becomes large for those that hardly deform.

Further, a small electric motor is required to have a high speed (30,000 rpm or more) in order to be downsized, and in order to reduce the vibration noise in that case, both the above-mentioned clearance stabilization and It is important to align the bearing centers. In particular, it is desirable to stabilize the clearance to about 10 μm if the diameter of the rotor shaft is about 2 mm.

The present invention has been made in view of the above circumstances, and an object thereof is to adjust the clearance between the rotor shaft and the bearing to be stably maintained at an appropriate value and to adjust the centers of the bearings to coincide with each other. An object is to provide a bearing device for a small electric motor that can be easily performed.

[0006]

[Means for Solving the Problems]

 In order to solve such a problem, a bearing device for a small electric motor of the present invention is a small electric motor in which both ends of a rotor shaft are rotatably supported by bearings having a substantially cylindrical shape provided on an inner peripheral surface of a bearing stand. In the above bearing device, at least one of the bearing mounts is formed into a cylindrical shape and a plurality of screw holes are formed in the peripheral wall toward the center, and the bearing is provided with a plurality of protrusions parallel to the axis on the outer peripheral surface thereof. A line that connects the vertices of this protrusion in a circle is formed to be larger than the diameter of the inner peripheral surface of the bearing stand, and the bearing is pressed into the bearing stand so that the protrusion overlaps the screw hole. The structure is such that the screws can be screwed together to align the bearing.

[0007]

[Action]

 According to this configuration, when the bearing is press-fitted into the bearing stand, the protrusion provided on the outer peripheral surface of the bearing is deformed as a press-fitting margin so that the bearing hole is hardly deformed. In case of misalignment, the push screw can be screwed into the screw hole of the bearing stand to finely adjust the bearing and align it.

[0008]

【Example】

 An embodiment of the present invention applied to an adderless brushless motor will be described below with reference to FIGS.

Reference numeral 1 denotes a rotor, which is formed by fixing a cylindrical permanent magnet 3 to a rotor shaft 2. Reference numeral 4 denotes a stator, which is composed of a punched and laminated stator core 5 and a coil 7 wound around an inwardly projecting magnetic pole through an insulating member 6. The motor case 8 has a cylindrical shape with a bottom, the stator 4 is fixed to the inner peripheral surface of the motor case by press fitting or bonding, and the bracket 9 is attached to the opening. The motor case 8 has a through hole 8a at the bottom, and the bearing base 10 is fixed to this. The bracket 9 also has a cylindrical shape with a bottom in the axial direction and has a through hole 9a at the bottom thereof, and the bearing base 11 is fixed thereto. The bearings 10 and 11 are equipped with bearings 12 and 13 at their centers by press-fitting or the like for rotatably supporting both ends of the rotor shaft 2. The bracket 9 is equipped with the hall element 14 and has a lead wire insertion hole and a coil terminal insertion hole for the hall element 14. Reference numeral 15 is a signal line for inputting the detection signal of the hall element 14 to the drive circuit (not shown).

Next, the main part of the present invention will be described. As shown in FIG. 3, the bearing base 10 (11) is made of a metal material such as brass and has a substantially bottomed cylindrical shape. The through-holes 10a, (11a) are formed on the outer periphery and the flange portion 10b (11b) is formed on the outer peripheral surface on the opening side. Further, the bearing base 10 fixed to the motor case 8 is provided with three screw holes 10c facing the center, which are located at equal intervals in the circumferential direction, on the peripheral wall thereof.

The bearing 12 (13) is made of a metal material such as a sintered alloy, and has a substantially cylindrical shape that can be accommodated inside the bearing stand 10 (11), and its center hole is the bearing hole 12 a. It becomes (13a). Then, on its outer peripheral surface, three protrusions 12b (13b) parallel to the axis are provided, and these protrusions 12b (13b) are formed by connecting the vertices of the protrusions in a circular shape to the bearing base 10 (11). ) Is larger than the diameter of the inner peripheral surface. Specifically, the protrusions 12b (13b) are formed such that their tips are rounded at a height of about 0.5 mm and are located at equal intervals in the circumferential direction.

These bearings 12 and 13 are press-fitted to the inner peripheral surfaces of the bearing bases 10 and 11, but the bearing 12 on the bearing base 10 side has a positional relationship such that the protrusions 12b and 13b overlap the screw holes 10c. Hold it. In this press-fitting, only the protrusions 12b and 13b are deformed and the bearing holes 12a and 13a are hardly affected, and the clearance between the rotor shaft 2 and the bearing holes 12a and 13a is stabilized to about 10 μm. Further, after this press-fitting, if adjustment and alignment are required to match the centers of both bearings 12 and 13, the push screw 16 is screwed into the predetermined screw hole 10c. Then, as the push screw 16 is screwed in, the tip of the push screw 16 presses the protrusion 12b to displace the center of the bearing hole 12a to a correct position by a very small amount for centering.

The present invention can be applied not only to brushless motors but also to general small motors that support the rotor shaft on both sides, and screw holes may be provided in the other bearing stand or in both bearing stands. The number of protrusions and screw holes is not limited to three, but three is economically most preferable.

[0014]

[Effect of the device]

 The bearing device for the small electric motor of the present invention, when the bearing is press-fitted into the bearing stand, the protrusions provided on the outer peripheral surface of the bearing are deformed as a press-fitting margin, so that the bearing hole is hardly deformed and the rotor shaft and the bearing are Clearance can be stably maintained at an appropriate value, and if the center of both bearings deviates due to this press-fitting, the push screw can be screwed into the screw hole of the bearing stand to finely adjust the center of the bearing. Aligning can be done easily.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention applied to a brushless electric motor.

FIG. 2 is an exploded perspective view thereof.

FIG. 3 is an exploded perspective view of a main part thereof.

FIG. 4 is an exploded perspective view of a main part of a conventional example.

[Explanation of symbols]

 1 Rotor 2 Rotor shaft 4 Stator 8 Motor case 9 Bracket 10, 11 Bearing base 10c Screw hole 12, 13 Bearing 12a, 13a Bearing hole 12b, 13b Protrusion 16 Push screw

Claims (1)

[Scope of utility model registration request] 1. A bearing device for a small electric motor, wherein both ends of a rotor shaft are rotatably supported by bearings having a substantially cylindrical shape provided on an inner peripheral surface of a bearing base, and at least one of the bearing bases is provided. The bearing is formed into a cylindrical shape and has a plurality of screw holes directed toward the center on the peripheral wall, and the bearing is provided with a plurality of protrusions parallel to the axis on the outer peripheral surface of the bearing. The bearing is press-fitted into the bearing base so that the projections overlap the screw holes and the projections overlap the screw holes, and the push screw is screwed into the screw holes of the bearing base to enable alignment of the bearing. Bearing device for small electric motors.