JPH07123630A - Small induction motor - Google Patents

Abstract

PURPOSE:To provide a small inexpensive induction motor usable in many ways with a small noise, by inserting by press a steel ring having three or more outer relief parts into a bearing bore part made of die-cast aluminum. CONSTITUTION:A steel ring 10 having six relief parts 11 press inserted into bearing bores 8 and 9 put at an aluminum die-cast housing 6 and an engine bracket 7. The steel ring 10 is supported at only six points out of these six relief parts 11, and the steel ring 10 is fixed in a body with the housing 6 and the end bracket 7. Then, the induction motor can be produced at low cost in a fully automated die-cast step. In addition, the press inserted part of the steel ring 10 that functions as a transmission path for oscillations by noises is put in partial contact at only six points, and thereby the oscillations are hardly transmitted and the noises are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized induction motor, and more particularly to a small-sized induction motor which produces low noise and is inexpensive.

[0002]

2. Description of the Related Art A small induction motor has many features such as a robust structure and high reliability, and it can be used as it is with a commercial power source, and has been widely used for driving various consumer appliances. However, there is a strong market need for further cost reduction and noise reduction, and in order to meet these needs, aluminum has been used for the frame because of its excellent heat dissipation and relatively large sound attenuation. However, the aluminum frame which has been used in the past has a drawback that it is not only expensive but also loud. In other words, even if the conventional aluminum frame is set so that the clearance between the ball bearing and the outer circumference of the ball bearing is small at the time of assembly in the bearing bore, the thermal expansion coefficient of aluminum is almost twice that of iron-based materials, so As a result of the rise, the gap expands, noise increases, and the bearing bore wears, resulting in a short life. On the other hand, in order to avoid such drawbacks, a method has been used in which an iron ring is integrally insert-cast in the bearing bore during die casting. However, this method has a drawback in that it is necessary to set an insert in a mold at the time of die-casting, unmanned die-casting is difficult and expensive. Furthermore, this method requires a pin to be attached to the die so that the insert does not move due to the pressure of the hot water in the die during die casting, and it is unavoidable that a pin hole reaching the iron insert remains in the appearance of the die casting. In addition to a design defect, there is a problem that moisture in the air reaches the iron insert through this hole and causes rusting.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art and to provide a small induction motor with low noise, low cost and a wide range of applications.

[0004]

[Means for Solving the Problems] The above-mentioned object is to have three
This is achieved by press-fitting an iron ring with reliefs in more than one place into the aluminum die-cast bearing bore.

[0005]

[Operation] In the case of a cylindrical iron ring with no escape,
Considering the variations in the diameters of the bearing bore and the iron ring, when trying to give a sufficient tightening margin even when the temperature rises, the difference in thermal expansion coefficient causes the rattling stress in the bearing bore to exceed the elastic limit at room temperature. Since it is difficult to realize the press-fitting method, it is necessary to provide three or more reliefs on the outer circumference of the iron ring so that the press-fitting contact with the bearing bore is made only at three or more places. It can be press-fitted and held within the elastic limit range without excessive tension stress.

[0006]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a compact induction motor according to the present invention. In FIG. 1, 1 is a stator having a stator coil 2, 3 is a rotor rotatably supported by ball bearings 4 and 5, and 6 and 7 are aluminum die-cast housings and end brackets which are the features of the present invention. In the inner diameter portions of the bearing bores 8 and 9, as shown in FIG. 2, the iron ring 10, which is a feature of the present invention having six relief portions 11 in the present embodiment, is provided in the outer diameter portion. It is press-fitted and supported only at the six parts that are not provided.

It is desirable that the press-fitted and supported portions are provided at three or more equal angles in order to concentrically and firmly support the ball bore rings 4 and 5 that support the rotor 3.

According to the embodiment of the present invention having the above-mentioned structure, the iron ring 10 can be integrated with the housing and the end bracket without the need for manual insert casting, so that the die casting work can be made unmanned. It can be manufactured at low cost.

Generally, noise and vibration generated in the rotor by receiving the electromagnetic force of the stator propagates to the frame via the bearing and the bearing bore to generate noise. According to the present embodiment, the noise vibration propagation path is used. Since the press-fitting portion of the iron ring 10 is partially contacted at six places, the propagation of noise vibration can be suppressed and the generation of noise can be reduced.

[0011]

As described above, according to the present invention, the die casting work can be unmanned, the operator can be freed from the high temperature environment, the manufacturing cost can be reduced, and the noise can be reduced. It has a great practical effect such as being made

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a small induction motor according to the present invention.

FIG. 2 is a plan view of an iron ring that is a feature of the present invention.

[Explanation of symbols]

1 ... Stator, 3 ... Rotor, 4, 5 ... Ball bearing, 6 ... Housing, 7 ... End bracket, 8, 9 ...
Bearing bore, 10 ... iron ring, 11 ... escape.

Claims (1)

[Claims] 1. A small motor induction having a stator, a rotor that generates torque by a rotating magnetic field generated by the stator, and a frame supporting the rotor and an aluminum die-casting housing, and an end bracket. A ball bearing for rotatably supporting the rotor through an iron ring press-fitted into a bearing bore portion provided in the housing and the end bracket, and a plurality of reliefs are provided on the outer circumference of the ring to form a bearing bore portion. A small induction motor characterized in that the press-fitting contact of is performed at multiple points.