JPH07184340A - Dynamo-electric machine - Google Patents

Abstract

PURPOSE:To provide a small-size and lightweight dynamo-electric machine with adequate strength by achieving the lightweight of a housing with use of a aluminum alloy and a synthetic resin such as phenol and epoxy. CONSTITUTION:In a dynamo-electric machine constituted of mounting end brackets 2A, 2B at both ends of a substantially cylindrical housing 1, the housing 1 is constituted by making the Young's modulus of a cylinder part in which a stator iron core 3a at the substantially center of the housing 1 is installed smaller than the Young's modulus of a cylinder part in which the stator iron core is not installed. Thereby, the disadvantage with respect to strength that an aluminum alloy and a synthetic resin such as phenol and epoxy is weak can be supplemented by a simple method, and consequently the rigidity of a housing can be increased and a small-size and lightweight dynamo-electric machine can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary electric machine such as an induction motor and, more particularly, to a rotary electric machine suitable for a general-purpose induction motor having a relatively small capacity using a light alloy or a resin for a housing.

[0002]

2. Description of the Related Art As a rotary electric machine such as a general-purpose induction motor having a relatively small capacity, a rotary electric machine having a structure shown in FIG. 9 has been generally used.

In FIG. 9, reference numeral 1 denotes a housing, which is also called a frame or a frame, and is formed into a substantially cylindrical shape by casting an iron-based material such as cast iron, and constitutes a casing of a rotary electric machine. A heat radiation fin 1a is integrally cast with the housing 1 and is radially formed on the outer periphery thereof.

2A and 2B are end brackets, also called bearing brackets, which are attached to both ends of the housing 1 by means of spigot fittings.

Reference numeral 3 denotes a stator, which is a stator core 3a made of a laminated body of silicon steel plates, and a stator wound around a plurality of slots provided on the inner circumference of the stator core 3a. It is composed of a coil 3b. 5 is a rotor, and a rotary shaft 6
And the rotating shaft 6 is rotatably held by the bearings 4A and 4B of the end brackets 2A and 2B, and the stator 3
The rotor 5 located inside is configured to rotate. Then, in such a rotary electric machine, the stator 3 is inserted into the housing 1 in advance and attached to the inner peripheral wall thereof, and then the rotor 5 is inserted into the stator 3 and the rotary shaft 6 is attached. The end brackets 2A and 2B are fitted on both ends of the housing 1 so that the bearings 4A and 4B are fitted to each other, and the end brackets 2A and 2B are fixedly attached to the housing 1 by a plurality of bolts (not shown). Has become.

One end side (right side in the figure) of the rotary shaft 6 is inserted through the bearing 4B of the end bracket 2B and protrudes to the outside to form an output shaft, but the other end side (left side) of the rotary shaft 6 is the end bracket 2A. An external cooling fan 9 (hereinafter, referred to as an external fan) is attached to a portion protruding from the bearing 4A.

Reference numeral 10 denotes an end cover, which forms a cover for covering the outer fan 9. And this end cover 10
Has an opening 10a for taking in outside air with the outside fan 9.
(Hereinafter, referred to as a ventilation inlet). Further, the opposite side of the opening 10a is formed into an open cylindrical shape or a deformed cylindrical shape, whereby a radial gap 10b is formed between the end bracket 2A and the outer diameter portion of the housing 1.
A ventilation outlet consisting of is formed.

Therefore, when the outer fan 9 is rotated by the rotor 5, the outside air is sucked from the ventilation inlet 10a of the end cover 10 and blown out from the gap 10b, whereby the end bracket 2A and the housing. 1
And ventilate the outside surface of the end bracket 2B,
It is designed to provide a cooling effect. The rotor 5 is mounted in the housing 1 of the rotary shaft 6 at a position facing the stator 2. The rotor 5 is provided with a secondary conductor bar (not shown) and an end ring 7. In addition, the internal cooling fan 8 (hereinafter,
The inner fan) is formed. This fan 8
Is composed of a plurality of blade blades projecting from both end surfaces of the end ring 7 in the axial direction, so as to ventilate the inside of the electric motor and obtain a cooling action.

That is, when the rotor 5 rotates, the inner fan 8 and the outer fan 9 also rotate accordingly, and the rotation causes the outside air to flow from the ventilation inlet 10a of the end cover 10 to the respective end brackets 2A and housings as indicated by the arrow a. 1 and the outer surface of the end bracket 2B are ventilated from the outside air to obtain cooling. Further, inside the electric motor, the air flow generated by the inner fan 8 passes through the rotor 5, the end ring 7, the stator coil 3b, and the stator core 3a while being cooled, and then passes through the housing 1. In comparison, the cooling is performed when passing through the end brackets 2A and 2B where the temperature rise is relatively low.

[0010]

The above-mentioned prior art cannot be said to consider light metalization or nonmetalization of the housing, and has the following problems.

When there is a strong demand for downsizing and weight reduction of rotating electric machines, the material of the housing is light aluminum and aluminum alloy material having good thermal conductivity (specific gravity is about 1/3 of steel,
Young's modulus is about 1/3, non-heat is about 2 times, thermal conductivity is about 3
There is a method in which heat generated inside the rotating electric machine is well transmitted to the housing to improve cooling, thereby making it possible to reduce the size and weight of the rotating electric machine.

On the other hand, there is also a method of using a synthetic resin such as phenol or epoxy (the Young's modulus of a simple substance is about 1/100 of steel) as the material of the housing in order to reduce the weight.

However, whichever material is used, the Young's modulus is as small as about 1/3 or less as compared with the iron-based material, and there is a problem that the strength is lowered. The present invention has been made to solve the above-mentioned problems, and secures the rigidity of the housing, and can be easily light alloyed or demetalized with an aluminum alloy or a synthetic resin such as phenol or epoxy, and can be cooled. It is an object of the present invention to provide a rotating electric machine that is sufficiently small and lightweight due to improved performance.

The rotary electric machine according to the present invention represented by an induction motor generally transmits power to a load by belting. When the belt is hooked, a lateral pulling load is applied to the rotary shaft of the rotating electric machine. This lateral pulling load acts on the end bracket and the housing that constitute the rotating electric machine with the bearing mounted on the rotating shaft as a fulcrum. When this situation is analyzed by the finite element method or the like, the largest stress acts on the tip of the housing cylinder and the housing root of the foot used for installing the rotating electric machine due to the lateral pulling load. At this time, if an aluminum alloy or a resin is used as the material of the housing, the mechanical strength (Young's modulus etc.) is lower than that of the iron-based material. On the other hand, since the lateral pulling load is determined by the transmitted torque, the stress value acting on each part is constant even if the material of the housing is changed. Therefore, if the material of the housing is changed to aluminum alloy or synthetic resin such as phenol or epoxy, the Young's modulus is small and the displacement increases. If the displacement increases, there is a possibility that the rotating electric machine cannot be used normally.

Therefore, in the housing according to the present invention, the Young's modulus of the portion where the stress is highest and the displacement occurs is as high as possible with respect to the other portions, and the displacement is reduced to an allowable range.

[0016]

In the housing of the rotating electric machine according to the present invention, the Young's modulus of the material forming the housing is smaller than that of the tubular portion on which the stator core at the center of the tubular portion is mounted. It is configured such that the cylindrical portion to which the stator core is not mounted is higher than the cylindrical portion. At the same time, the Young's modulus of the foot portion for installing the rotating electric machine is increased.

Next, the reason for limiting the range of increasing the Young's modulus will be described.

If the cylindrical portion of the housing in which the stator core is mounted has a mechanical strength equal to or higher than that of the stator core (a laminated body of silicon steel plates), the stator core is press-fitted or shrink-fitted. As a result of the mounting on the housing, displacement occurs in the inner diameter portion of the stator core after mounting. When this displacement occurs, it causes magnetic noise.

However, if the strength of the cylindrical portion is lower than that of the stator core, displacement occurs on the outer periphery of the housing and displacement does not occur on the inner diameter portion of the stator core.

Needless to say, the Young's modulus of the foot is increased, and the purpose is to improve the strength of the foot.

[0021]

In the housing according to the present invention, the stress is highest and the Young's modulus of the portion where the displacement occurs is as high as possible with respect to the other portions, so that the displacement can be reduced to an allowable range.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotary electric machine according to the present invention will be described below in detail with reference to the illustrated embodiments.

FIG. 1 shows an embodiment in which the present invention is applied to a general-purpose induction motor. In FIG. 1, 11 is a metal lath, and the others are the same as the conventional example described in FIG.

In this embodiment, the housing 1 is made of an aluminum alloy material having a good thermal conductivity and is produced by die-casting with a good productivity. At this time, the metal lath 11 is integrally formed at the same time.

Next, the metal lath 11 in this embodiment
The housing 1 having the above will be described in more detail with reference to FIGS.

First, the metal lath 11 has the shape shown in FIG. 4, and as shown in FIG. 2, except for the cylindrical portion where the stator core is mounted near the center of the housing 1, from the end of the stator core to the tip thereof. Insert it into the cylinder where the stator core is not attached. Then, it is integrally formed with the housing 1 by die-casting with good productivity. Therefore, metal lath 1
In other words, the tubular portion having no stator core is provided only with an aluminum alloy material.

FIG. 3 is an external view of the housing according to the present invention as viewed from the front. The metal lath 11 is inserted between the outer diameter and the inner diameter of the housing 11 as shown in the drawing.

Next, an embodiment of the present invention in which a resin is used as the main material of the housing will be described with reference to FIG.

In the figure, the reinforcing fiber 12 is a three-dimensionally reinforced reinforcing fiber material such as carbon fiber. Others are the same as the conventional example described in FIG.

In this embodiment, a composite material made of a lightweight synthetic resin such as phenol or epoxy resin and a hardening material such as quartz or sand is used as a main material constituting the housing 1 and is manufactured by injection molding with high productivity. At this time, the reinforcing fibers 12 are simultaneously formed integrally.

Next, the housing 1 having the reinforcing fibers 12 in this embodiment will be described in more detail with reference to FIGS.

First, as the reinforcing fiber 12, for example, a carbon fiber or the like having a shape shown in FIG. 8 and reinforced in three dimensions in the longitudinal, lateral and length directions is used. As shown in FIG. 6, the reinforcing fibers 12 are inserted into the cylindrical portion of the housing 1 from the end to the tip of the housing 1 where the stator core is not mounted, except for the cylindrical portion near the center where the stator core is mounted. To do.
Then, it is formed integrally with the housing 1 by injection molding.
Therefore, the tubular portion without the reinforcing fibers 12 is made of only the resin material.

Next, the function and effect of this embodiment will be described.

The rotary electric machine according to the present invention represented by an induction motor generally transmits power to a load by belting. When the belt is hooked, a lateral pulling load is applied to the rotary shaft of the rotating electric machine. This lateral pulling load acts on the end bracket and the housing that constitute the rotating electric machine with the bearing mounted on the rotating shaft as a fulcrum. When this situation is analyzed by the finite element method or the like, the largest stress acts on the tip of the housing cylinder and the housing root of the foot used for installing the rotating electric machine due to the lateral pulling load. At this time, when an aluminum alloy or a synthetic resin such as phenol or epoxy is used as the material of the housing, the mechanical strength (Young's modulus etc.) is lower than that of an iron-based material such as cast iron. On the other hand, since the lateral pulling load is determined by the transmitted torque, the stress value acting on each part is constant even if the material of the housing is changed. Therefore, when the material of the housing is changed to aluminum alloy or resin, the Young's modulus is small and the displacement increases. If the displacement increases, the stator and the rotor may come into contact with each other, and the rotating electric machine may not operate normally.

Therefore, in the housing according to the present embodiment, the Young's modulus of the portion where the displacement occurs is made as high as possible with respect to the other portions, the strength is improved and the displacement is reduced to a permissible range. That is, when the material forming the housing is a material having a lower strength than an iron-based material such as an aluminum alloy or a synthetic resin such as phenol or epoxy, the strength and rigidity are improved.

Next, the reason for limiting the range of increasing the Young's modulus will be described.

If the cylindrical portion of the housing in which the stator core is mounted has a mechanical strength equal to or higher than that of the stator core (a laminated body of silicon steel plates), the stator core is press-fitted or shrink-fitted. After mounting, the displacement occurs in the inner diameter portion of the stator core due to the press-fitting margin and the shrink-fitting margin of both after mounting. When this displacement occurs, the imbalance of the gap between the stator and the rotor increases, and as a result, the load applied to the bearing increases and magnetic noise increases. However, if the strength of the cylindrical portion is weaker than that of the stator core, displacement occurs on the outer periphery of the housing and displacement does not occur on the inner diameter portion of the stator core.

By constructing as described in the above embodiment, not only the mere drawback in strength of the material used for the housing is compensated, but also the size and weight are small, the assembling accuracy is good, the vibration and noise are low, and the reliability is high. A rotating electric machine can be provided.

It should be noted that it is obvious that if the above-mentioned method is adopted for the foot portion of the housing, the foot portion can be easily reinforced, and therefore detailed description thereof will be omitted.

According to this embodiment, the following effects can be obtained.

1. The weakness of aluminum alloy or resin, which is weak in strength, can be compensated by a simple method, and as a result, the rigidity of the housing can be improved.

2. A small and lightweight rotating electric machine can be provided.

3. It is possible to provide a rotating electric machine with good assembly accuracy and low vibration and noise.

4. As a result, a highly reliable rotating electric machine can be provided.

[0045]

According to the present invention, in a rotating electric machine constructed by assembling end brackets at both ends of a substantially cylindrical housing, the Young's modulus of a tubular portion to which a stator core is not mounted is set to approximately the center of the housing. Since the housing is constructed so as to be larger than the Young's modulus of the cylindrical portion in which the stator core in the vicinity is mounted, it is possible to make up for the weakness of strength of aluminum alloy or resin by a simple method. As a result, the rigidity of the housing can be improved. Further, it is possible to obtain the effect that it is possible to provide a rotating electric machine with good assembly accuracy and low vibration and noise.

[Brief description of drawings]

FIG. 1 is a side view of an external partial cross section of a rotating electric machine showing an embodiment of the present invention.

FIG. 2 is a detailed view of an external partial cross-sectional side view of a rotating electric machine showing an embodiment of the present invention.

FIG. 3 is an external front view of an aluminum alloy housing showing an embodiment of the present invention.

FIG. 4 is an external view of a metal lath showing an embodiment of the present invention.

FIG. 5 is a partial sectional side view of the external appearance of a synthetic resin housing rotating electric machine showing another embodiment of the present invention.

FIG. 6 is a detailed view of an external partial cross-sectional side view of a synthetic resin housing rotating electric machine according to another embodiment of the present invention.

FIG. 7 is an external front view of a synthetic resin housing showing another embodiment of the present invention.

FIG. 8 is an external view of a reinforcing fiber showing another embodiment of the present invention.

FIG. 9 is a side view of an external partial cross-section of a conventional rotating electric machine.

[Explanation of symbols]

1 ... Housing, 1a ... Radiating fin, 2A, 2B ... End bracket, 3 ... Stator, 3a ... Stator core,
3b ... Stator coil, 4A, 4B ... Bearing, 5 ... Rotor, 6 ... Rotating shaft, 7 ... End ring, 8 ... Inner fan, 9 ... Outer fan, 10 ... End cover, 10a
… Ventilation port, 11… Metal lath, 12… Reinforcement fiber,

Claims (1)

[Claims] 1. A rotating electric machine constituted by assembling end brackets at both ends of a substantially cylindrical housing, and a cylinder in which a stator core near substantially the center of the housing is attached to a material forming the housing. A rotary electric machine, wherein the Young's modulus of the portion is made smaller than the Young's modulus of the tubular portion to which the stator core is not mounted, and the housing is configured.