JPS5821337Y2 - small motor shaft - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a shaft of a small motor in which the shaft is electrically insulated and has increased hardness.

Conventionally, the shaft of a small motor is made of iron-based conductive metal material, and when the rotor is assembled, as shown in Figure 1,
An insulating material 46 is fitted onto the shaft 45, and a rotor core 47 is fitted onto the outer periphery of the insulating material 46.

If the shaft 45 and the rotor core 47 are not electrically insulated as described above, since both are conductive, electrical noise will occur, which will adversely affect other electrical circuits.

On the other hand, when the insulating material 46 is interposed as described above, the space factor is poor and the rotor becomes large.

Furthermore, the use of an insulating material increases the number of parts and costs, and has the drawback of poor workability.

An object of the present invention is to provide a shaft for a small motor in which the shaft and rotor core are electrically insulated and the surface hardness of the shaft is increased to improve wear resistance.

A feature of the present invention is that a metal oxide layer is formed on the surface of the shaft, and the rotor core is fitted through this metal oxide layer.

The present invention will be explained below with reference to illustrated embodiments.

In FIGS. 2 and 3, the small motor has a stator magnet 3, a rotor 4, and a pair of brushes 5 arranged in a container made of a cup-shaped case 1 and an end bracket 2, and a shaft 41 of the rotor 4 is connected to the case 1. and are pivotally supported by bearing metals 11 and 21 fixed to the end bracket 2, respectively.

The rotor 4 has a shaft 41 fitted with a rotor core 42 and a commutator 43 in which a plurality of layers of magnetic material are laminated.

A rotor coil 44 is wound around the rotor core 42,
The lead end of the coil is connected to a commutator 43.

The stator magnet 3 is located outside the rotor core 42.
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The pair of brushes 5 are in sliding contact with the cotter 43.

The brush 5 is fixed to a brush holder 51 fitted into the inner bottom of the end bracket 2.

The shaft 41 is prepared by cutting a round bar-shaped aluminum material of, for example, 0.5 mm to 10 mm into a predetermined size, and the surface of the shaft 41 has a thickness of several microns, preferably 10 μm, as shown in FIG. A metal oxide layer 41a such as alumite is formed thereon by anodic oxide film treatment.

The shaft material may be made of an alloy containing iron as a main component and chromium, etc., and the shaft material may be subjected to heat treatment, etc., and a metal oxide layer may be formed on the surface by a method such as vapor phase growth followed by diffusion.

Metal oxide layer 41 formed on the surface of the shaft 41
In a, the boundary between the main metal material and the oxide may be clear as shown in Figure 4 A, or the density of the oxide may become coarser towards the center as shown in Figure 4. It may be formed into

Further, it is preferable that the oxide layer 41a has porosity of about several microns, which is a kind of crack or hole caused by the processing process.

Particularly in the shaft of this type of motor, if the porous material is impregnated with a lubricant such as oil or resin, the friction between the shaft and the bearing metals 11 and 21 on which the shaft is supported can be reduced.

When the shaft 41 having the metal oxide layer formed on its surface is fitted into the rotor core, it is directly fitted without using an insulating material.

Since the present invention is configured as described above, the shaft and the rotor core are electrically insulated, and there is no need to insert a separate insulating material, which facilitates assembly work and allows the rotor to be made smaller.

Further, since the metal oxide layer has hardness, the wear resistance of the shaft is improved.

Furthermore, since extremely small pores are formed in the metal oxide layer, bearing oil and the like can be easily retained, making it easier to form an oil film, thereby increasing the lateral pressure resistance.

Furthermore, when a highly lubricating material such as fluorine resin is added to the porous material, a shaft for a small motor can be obtained which has excellent effects such as improved side pressure resistance.

[Brief explanation of drawings]

Figure 1 is a cross-sectional side view of a rotor assembled using a conventional shaft, Figure 2 is a cross-sectional side view of the case of a small motor using the shaft of the present invention, and Figure 3 is a cross-sectional view of the same rotor. The side view and FIG. 4 are sectional views of the same shaft. 1... Case, 2... End bracket, 3... Stator magnet, 4...
・Rotor, 5...Brush, 11, 21...
...Bearing metal, 41...Shaft, 41a.
... Metal oxide layer, 42 ... Rotor core, 43 ... Commutator, 44 ... Rotor coil.

Claims (1)

[Scope of utility model registration request] A shaft of a small motor that has a porous metal oxide layer formed on its surface and a rotor core fitted through this metal oxide layer.