JPS59230453A - Axial air gap type induction motor - Google Patents

Abstract

PURPOSE:To enhance the strength and to reduce the resistance of a rotor by forming the rotor to have a wadge-shaped section, and forming an air gap between the rotor and a stator so that the outer peripheral side is narrow and the inner peripheral side is wide. CONSTITUTION:An air gap surface 6 of a rotor 5 made of a good conductive metal disc is formed in wedge-shaped section. In other words, the air gap is formed so that the outer periphery is thin and the inner periphery is thick. The air gap between the stators is narrow at the outer peripheral side, and slightly wide at the inner peripheral side. When the end rings 7, 8 of the inner and outer peripheral are formed in section so that the outer peripheral side is slightly larger than the inner peripheral side, they are convenient in a brake function. The thicknesses of the rings 7, 8 are slightly thicker than the air gap 6.

Description

[Detailed Description of the Invention] Industrial Application Field General industrial machines, such as robots, industrial sewing machines, and machine tools, require electric motors with good controllability. If you need
Electric motors with rotors of low inertia are used. The present invention relates to an axial gap type induction motor used for this purpose.

Conventional structure and its problems The above-mentioned applications usually require a motor with a direct current ironless armature (
DC coreless motors are used and have excellent controllability, but they also have wear parts such as commutators and brushes, so maintenance is required, and so-called brushless motors are in demand. . Brushless motors include synchronous motors and induction motors, but there are induction motors with a coreless rotor structure that do not require a slip ring for power supply. 1st
The figure shows the general structure of this type of motor.
1' is an annularly wound iron core provided with stator winding 2, which acts to generate a rotating magnetic field, and is arranged in pairs facing each other.
The rotor 3 is a disk with a metal (copper, aluminum, etc.) with good conductivity on the gap surface. The structure is such that a rotational force of 9 is generated from the shaft 4.

However, in the electric motor having the above structure, the air gap between both stators is determined by the thickness of the rotor 3, and if the resistance of the rotor 3 is to be reduced and the torque is increased, the thickness of the rotor 3 must be increased. The thickness of the motor becomes thicker, the air gap length increases, the air gap ampere-turn increases, the exciting current of the motor increases, the power factor becomes poor, and the characteristics deteriorate. Therefore, rotor 3
In order to reduce the thickness of the rotor as much as possible without increasing the resistance, a method has been proposed in which several end rings are placed on the inner and outer circumference of the rotor.

However, in this method, since the thickness of the void is uniform, the strength on the inside is weaker, and the distributed resistance is also higher because the area is smaller than on the outside.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is intended to solve the problems of strength and resistance.

Structure of the Invention The present invention is characterized in that the shape of the rotor is not uniform in plate thickness, and the inner and outer peripheral end ring parts are thicker than the plate thickness in the cavity part, and in the cavity surface part, the plate thickness is thinner on the outer peripheral side and thinner on the inner peripheral side. The stator is thick and has a wedge-shaped cross section, and the gap between the stators is narrow on the outer circumferential side and slightly wider on the inner circumferential side.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 2 to 5. Note that components that are the same as those in the conventional configuration described above will be described using the same numbers.

FIGS. 2 and 3 show a rotor, in which the rotor 6 is made of a metal disc with good conductivity, and the cavity surface 6 of the rotor 6 is formed into a wedge-shaped cross-section. That is, the outer circumference is thin and the inner circumference is thick. Note that it is convenient for the brake function to form the end ring portions 7 and 8 on the inner and outer circumferential portions so that the outer circumferential side is slightly larger in cross section than the inner circumferential side. End ring part 7
, 8 are slightly thicker than the gap surface portion 6. The optimum dimensions are determined through experiments. 9 is a ventilation hole.

Due to the structure of the rotor 5 described above, the space between the stators is necessarily narrower at the inner circumference than at the outer circumference. Figure 4 shows a mutual relationship diagram. A stator having such a structure can be easily manufactured by deforming the wound core 10.

When applying a mechanical brake to the rotor 6 of this structure,
The outer end ring surface can be used as a braking surface. Reference numeral 11 denotes a brake, which is a so-called disc brake in which braking force is obtained by tightening the outer peripheral end ring portion 8.

An example of cross-sectional dimensions of the cavity surface portion 6 of the rotor 6 will be explained with reference to FIG. The radius and thickness of the inner circumference and the radius and thickness of the outer circumference are r1. L 1. If r 2 r j 2, then if we imagine that the current flows radially and draws a fan-shaped loop as shown in Figure 5, then assuming that the cross-sectional area ratio is the same, we have the relationship r1/r2-t2/11. Make it.

As an example, r=50mm, r2==80 cylinder, t2
If there are 21 cylinders, then t1=-X1=1.6 cylinders.

5.Also, the dimensions of the end ring parts 7 and 8 should be determined by experiment, but if they are too thick, the inertia will increase.
In addition, since the dimensions (thickness) of the material are also large, the thickness is set to 2t1-3t2=3.2-3.

Width is inside ≦ outside 5t1~6t2=8~6 throat W1+5
Listening level: W2-8.

In addition, for the friction material of the disc brake, a material that is compatible with the conductor (for example, copper) and has little wear is selected.

Effects of the Invention As is clear from the above description, the present invention provides the following effects.

1) The inner plate thickness of the rotor disk is thicker than the outer plate thickness, which is advantageous in terms of strength.

2) Compared to the case of uniform plate thickness, the rotor resistance can be lowered, and the current density and therefore the temperature rise can be made uniform.

3) Since the outer end ring portion can be used as a friction surface for a mechanical brake, the structure with a brake is simplified.

As an overall effect, the plate thickness of the rotor in the air gap can be reduced by 11 mm, so the excitation ampere-turns of the motor are reduced, the excitation current is reduced, and the power factor is improved. At the same time, the rotor resistance is relatively reduced due to the end ring effect, so current flows easily to the rotor disk, and the torque and output do not decrease. Further, due to the above effect, the efficiency of the motor can be improved to 1"11 (by a few degrees) compared to a motor with a normal rotor structure without reducing the strength of the rotor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional two-length axial gap type induction motor, FIGS. 2(a) and (b) are a front view and a sectional view showing the rotor structure of the motor of the present invention, and FIG. 3 4 is an enlarged sectional view of the same essential parts, FIG. 4 is a sectional view showing the overall structure of the electric motor of the present invention, and FIG. 5 is a virtual diagram of the current path flowing through the rotor. 2...Stator winding, 6...Rotor, 6
...Gap surface part, 7...Inner end ring, 8...Outer end ring, 1o...
Wound core. Name of agent: Patent attorney Toshio Nakao and 1 other person
3 Figure 4 Figure 5

Claims (2)

[Claims] (1) Two stators are made by winding an annular wound iron core and are arranged facing each other with a gap in the axial direction. The rotor has a wedge-shaped cross-section, the inner and outer end ring portions being thicker than the plate thickness of the cavity, and the plate thickness of the cavity face portion being thinner on the outer circumference side and thicker on the inner circumference side. On the other hand, the gap between the inner stators is narrower on the outer circumferential side and slightly wider on the inner circumferential side. (2) The axial gap type induction motor according to claim 1, wherein the outer peripheral end ring portion is configured as a sliding surface of a mechanical brake.