JPH08205492A - Rotor of squirrel-cage type induction motor - Google Patents

Abstract

PURPOSE: To prevent local heating of a rotor bar in an iron core and effectively reduce the temperature of the rotor. CONSTITUTION: In a squirrel-cage type induction motor for vehicle comprising a rotor bar inserted into a slot provided on a rotor iron core and an end ring for short-circuiting the rotor bar at both ends thereof, a plate-loop type heat pipe 3 is attached to the rotor bar. Moreover, the rotor bar is provided with the function of the plate-loop type heat pipe 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a basket type induction motor, and more particularly to a structure in which a loop-shaped heat pipe is formed on a rotor bar and a short circuit ring of an induction main motor for vehicles.

[0002]

2. Description of the Related Art A conventional rotor of an induction motor for a vehicle will be described with reference to a vertical sectional view of FIG. Rotor core 4
Is an iron core retainer 5 attached to the rotor shaft 6 and pressed from both sides.
Fixed by. The rotor core 4 has a plurality of slots, and a rotor bar 1 manufactured by pulling out a material such as brass pushed into the slots and a method such as attaching silver rollers to both ends of the rotor bar 1. It has a short circuit ring 2 made of copper which is fixed by using. Further, bearings 7 are provided at both ends of the rotor shaft 6.
Is attached to a stator frame (not shown) by.

Further, the rotor core 4 and the core retainer 5 are provided with air holes 4a. Also, the stator structure will be described. The stator core 8 having the stator coil 9 mounted thereon has an outer frame 10
The stator core 8 and the rotor core 4 are attached to each other with a gap G therebetween. Cooling of the rotor is performed by dividing the cooling air taken in from the intake side into the cooling air Q1 passing through the gap G and the cooling air Q2 passing through the air holes 4a and flowing to the exhaust side.

[0004]

The main heat source of the rotor is the rotor bar 1. (See Fig. 5) This rotor bar 1
In the above, the portion of the rotor core 4 that is exposed to the outside is cooled by the cooling air Q1 passing near the surface of the rotor core 4.
Most of the rotor bars pushed into the slots of the rotor are transmitted to the rotor core 4 and are discharged to the outside of the main motor by the cooling air passing through their surfaces. Further, a part of the amount of heat transmitted to the rotor core 4 passes through the rotor shaft 1 and raises the temperature of the bearings 6 at both ends. Therefore, the temperature of the rotor bar 1 had a temperature gradient T1 as shown in FIG. 4 depending on the location.

As shown in FIG. 5, the cage rotor does not have an insulator, and therefore the temperature rise limit is not specified. However, in reality, restrictions such as surface coating applied for the purpose of rust prevention, restrictions on strength reduction due to hardening of the rotor bar 1 at high temperatures, restrictions on the influence on the rotor coil 9 due to heating of the rotor bar, and bearing portions. Regarding the above, there is a restriction that the temperature rise of the rotor can be suppressed to a low level due to the restriction of the thermal condition of the lubricating grease, and therefore there are drawbacks such that the structure of the electric motor must be enlarged and the cooling air must be increased. In particular, in induction traction motors for vehicles, downsizing and large capacity are indispensable in line with the demand for power concentration and high speed.

[0006]

According to the present invention, the amount of heat generated in the portion of the rotor bar 1 which is the main heat source of the rotor inserted in the rotor core 8 portion is transmitted to the portion outside the core. In order to dissipate heat efficiently with cooling air, a plate loop heat pipe is provided on the rotor bar. That is, the means fixes the plate type loop heat pipe manufactured by injecting the two-phase condensable hydraulic fluid into the loop hollow small hole passage and sealing it to the rotor bar surface. This plate-shaped loop heat pipe is made of a conductive material such as copper and has a part of the rotor bar. The rotor mubber itself is provided with a preliminarily hollow small hole passage so that the passage has a loop shape, and a two-phase condensable hydraulic fluid is injected and sealed. At this time, the passage is looped by using each rotor bar or a plurality of rotor bars.

[0007]

The operation is performed by fixing the plate type loop heat pipe to the surface of the rotor bar or by providing the rotor bar itself with the function of the loop heat pipe so that heat is generated in the high temperature part and the low temperature part of the rotor bar. The exchange action is performed to equalize the temperature rise of the rotor bar.

[0008]

EXAMPLES Examples will be described with reference to FIGS. FIG. 1 is a simplified diagram showing an embodiment of the present invention. The rotor bar 1 has plate-loop heat pipes 3 fixed to the surface in the direction of the air gap G so that the rotor bar 1 can easily receive heat conduction. This plate / loop heat pipe 3
Will be described in detail with reference to FIG. A hollow small hole passage forming a loop is provided inside the plate of a material suitable for the rotor bar such as brass and copper-zinc alloy, and the two-phase condensable hydraulic fluid LQ is injected and sealed to achieve the function of the heat pipe. I have it.

Another embodiment is shown in FIG. The rotor bar 1a is provided with a hollow small hole 1b as shown in FIG. 3 (b), and as shown in FIG. It is joined so that the hollow eyelets communicate. The hollow small hole 1b communicates with a part or the whole of the rotor bar and forms a loop, and has a function of a heat pipe by injecting and sealing the two-phase condensable hydraulic fluid LQ. It is of course possible to use a plate having the structure shown in FIG. 2 as the rotor bar. That is, by providing the rotor bar of the present invention with the function of a looped heat pipe, the temperature rise of the rotor bar inside and outside the rotor core can be reduced from T1 to T2 shown in FIG.

[0010]

In the rotor bar to which the plate loop heat pipe is fixed according to the present invention, or in the rotor in which the rotor bar is formed into the loop heat pipe, it is possible to reduce the temperature rise of the rotor bar inside the iron core. Therefore, it is possible to suppress the temperature rise of the bearing portion and the temperature rise of the iron core surface lower than before. Therefore, if the temperature rise is about the same, it is possible to reduce the size and weight of the induction motor and increase its power.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a squirrel-cage induction motor having a rotor with plate-loop heat pipe according to the present invention.

FIG. 2 is an enlarged perspective view of a plate / loop heat pipe.

3A is a perspective circuit diagram in which a loop-shaped heat pipe is provided on a rotor bar and a short-circuit ring, and FIG. 3B is a perspective view of a rotor bar having hollow small holes.

FIG. 4 is a comparison diagram of the temperature distribution of the rotor bar in the conventional case and the case of the present invention.

FIG. 5 is a vertical sectional view of a conventional squirrel cage induction motor.

[Explanation of symbols]

 1 Rotor Bar 1a Rotor Bar with Hollow Small Hole 1b Small Hole 2 Short Circuit Ring 2a Short Circuit Ring with Small Hole 3 Plate Loop Heat Pipe 4 Rotor Iron Core 4a Wind Hole 5 Iron Core Presser 6 Rotor Shaft 7 Bearing 8 Stator Iron Core 9 Stator Coil 10 Outer frame Q Air gap G Cooling air L Rotor core length T1 Conventional rotor bar temperature rise T2 Rotor bar temperature rise of the present invention LQ Two-phase condensable hydraulic fluid

Claims (2)

[Claims] 1. A rotor having a laminated core on a rotor shaft, a rotor bar inserted into a slot provided in the laminated core, and a rotor having short-circuit rings at both ends of the rotor bar,
A rotor of a basket-type induction motor having the shape and structure of a rotor in which a plate-loop heat pipe (3) is fixed on the rotor bar and the short-circuit ring. 2. A hollow small hole is formed in the rotor bar and both short-circuit rings to form a loop-shaped passage, and a two-phase condensed working fluid is sealed and sealed in this passage. The rotor of the basket induction motor according to claim 1, which is configured as described above.