JPH0946988A - Rotor of induction motor for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the workability by providing a cylindrical part to cover a bonded part of an end ring to be bonded to the tip of a rotor bar from its outer circumference, and providing a rotor in which a shrink ring is fitted over the outer circumference of the cylindrical part. SOLUTION: A notch to reduce the height of a conductor is made in a part to be projected from the side of a rotor core 4 in a rotor bar 31 to form an outer circumferential surface of the dimension smaller than the outer diameter of the rotor, and the outer diameter of the shrink ring is smaller than that of the rotor. An annular groove of rectangular section is provided in the side of a cylindrical end ring 32, and the groove width is approximately equal to the height of the conductor at the tip of the rotor bar, and the groove depth is approximately equal to 1/2 of the width of the end ring. The rotor bar is inserted in the rotor core to cover the end part by the annular groove or a flange, and after the rotor bar tip part is brazed with an abutting part of the end ring, the outer diameter of the shrink ring flitting surface is measured, and the shrink ring is externally fitted. As a result, the workability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squirrel-cage induction motor used as a main motor for driving an electric vehicle such as a railway vehicle,
More specifically, the present invention relates to improvement of a structure in which a shrink ring is externally fitted to a joint between a rotor bar of a rotor and an end ring.

[0002]

2. Description of the Related Art A main motor for a vehicle has many dimensional constraints due to track width, wheel diameter, etc. in design, and a conventional long motor cannot be stored in an electric trolley and is not suitable for a vehicle. Therefore, usually, the shape tends to be relatively large and flat, and the peripheral speed of the rotor tends to be high, and careful measures for the mechanical strength of the rotor due to the influence of centrifugal force generated during high-speed rotation are required.

FIG. 6 is a partial vertical sectional view of a general squirrel-cage induction motor used as a main motor for a vehicle. For a rotor having a rotation speed of more than 4000 to 5000 per minute,
1 shows an example in which a shrink ring 3 is provided at the joint between the rotor bar 1 and the end ring 2 to prevent the rotor bar from bending due to centrifugal force.

In FIG. 6, the rotor bar 1 is regarded as a cantilever having a fixed end at the portion inserted into the rotor core 4 and a free end at the tip portion protruding from the side surface of the rotor core, and the end ring 2 is regarded as a cylinder. Due to the centrifugal force generated when the rotor rotates at high speed, the free end of the portion regarded as the cantilever of the rotor bar bends in a direction radially away from the rotor shaft center, and the end ring also expands in the outer radial direction. Therefore, in order to prevent the displacement due to this bending and expansion from exceeding the limit, the shrink ring is tightly fitted and the rotor bar tip and end rings are joined together and externally fitted to the part, and centrifugal force is applied in the rotor shaft center direction. Pressing against it is performed.

On the other hand, the outer diameter of the shrink ring must be smaller than the inner diameter of the stator in order to insert and remove the rotor from the stator when assembling and repairing the electric motor.
Since the rotor bar is stored in a very shallow part of the rotor surface, if the conductor height of the rotor bar remains constant and protrudes from the side surface of the rotor core, and the shrink ring is fitted on that part, its thickness is It must be extremely thin, and there is also a means for tightening by winding a piano wire or the like, but since tightening may be uneven, the effect is thin and impractical, even though it is time-consuming. Therefore, by lowering the conductor height of the rotor bar at the portion protruding from the side surface of the rotor core, it is possible to fit a shrink ring with an appropriate thickness and an outer diameter smaller than the inner diameter of the stator, and insert it into or out of the rotor and the stator. The structure will not hinder the operation.

The cross-sectional shape of the rotor bar depends on the conductor height.
A rectangular deep groove shape with a long side of 10 mm or more is adopted to reduce bending in the direction in which centrifugal force acts and to maintain mechanical robustness, and to protect the part protruding from the side surface of the rotor core. A ridge of the conductor formed at a right angle in the cross section of the conductor is chamfered by about 1 C (1 mm × 1 mm) to prevent so-called loose bar breakage in which the rotor bar is broken due to stress concentration during rotation.

[0007]

FIG. 3 is an enlarged partial vertical side view showing a state where the rotor bar and the end ring of the conventional example are joined and a state where a shrink ring is externally fitted to this joined portion. In FIG. 3, the tip end portion of the rotor bar 11 protruding from the side surface of the rotor core 4 and the side surface of the cylindrical end ring 12 are abutted against each other and brazed, and then the outer peripheral surface of this joint portion is machined to form the shrink ring 13. Although it is externally fitted, the chamfered portion provided on the ridge of the rotor bar may be scraped off depending on the degree of machining, and in this case, the chamfered portion is chamfered again.

However, since there are many rotor bars and the work space is narrow, the work is troublesome and takes a lot of time. In addition, fine metal cutting dust generated by machining or re-chamfering remains, and in the future, bearings will be used. Careful cleaning is necessary to prevent malfunctions from being mixed into parts, etc.
For this reason, there is a drawback that it takes more working time and is economically disadvantageous.

Therefore, another conventional example devised for the purpose of avoiding the re-chamfering work of the rotor bar will be described with reference to FIGS. FIG. 4 is an enlarged partial vertical side view similar to FIG.
FIG. 5 is seen from the FIG. In FIG. 4, a groove is provided in the end ring 22 parallel to the axial length direction so as to match the slot groove cross-sectional dimension and slot pitch of the rotor core 4, and the tip end portion of the rotor bar 21 is inserted into this groove and brazed to each other. After that, the outer peripheral surface of this joint is machined and the shrink ring 23 is externally fitted, but by making the machining width within the width dimension of the end ring, the rotor bar outside the groove of the end ring is machined. Therefore, the re-chamfering work of the rotor bar can be avoided.

However, during machining of the surface to which the shrink ring is fitted, cutting wastes in which the end ring material and the rotor bar material are intermittently intermittently generated are left as fine dust and remain in many cases. It has the drawback that it takes a long time for cleaning work, and it is not always economically economical to provide a groove for inserting the tip of the rotor bar on the end ring at each slot pitch, and the shrink ring is fitted on the outside. The workability to do so cannot be dramatically improved.

An object of the present invention is to provide a rotor of a squirrel-cage induction motor having a structure that facilitates workability of fitting a shrink ring onto a joint between a rotor bar and an end ring.

[0012]

[Means for Solving the Problems] In other words, a means for achieving this object is a car in which an end ring is joined to a tip of a rotor bar protruding from a side surface of a rotor core, and a shrink ring is externally fitted to the joined portion. In the shaped rotor,
The end ring joined to the tip of the rotor bar is formed to have a cylindrical portion that covers the joined portion from the outer periphery, and a shrink ring is externally fitted to the outer periphery of the cylindrical portion to form a rotor of an induction motor for a vehicle. .

[0013]

The end ring itself is formed so as to cover the joint between the tip of the rotor bar and the end ring, and the joint is not machined. Therefore, it is possible to save the cleaning time associated with the generation of dust of cutting waste as in the conventional example. This dramatically improves the workability of fitting the shrink ring.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged partial vertical side view for explaining an embodiment of the present invention, in which an annular groove provided on a side surface of an end ring 32 has a joint with a rotor bar 31, and a position corresponding to the outer periphery of the joint. And, it shows a state in which the shrink ring 32 is fitted onto the outer peripheral surface of the end ring.

In FIG. 1, a portion of the rotor bar 31 projecting from the side surface of the rotor core 4 is preliminarily subjected to the following preparatory processing before inserting the rotor bar into the rotor core as in the conventional example. That is, when the rotor bar is inserted into the rotor core, the portion of the rotor bar located on the outer peripheral surface side of the rotor is cut to reduce the conductor height to form an outer peripheral surface having a size smaller than the outer diameter of the rotor. The outer diameter of the shrink ring should be smaller than the outer diameter of the rotor core.

The processing of the rotor bar is first carried out from the side surface of the rotor core for the purpose of relaxing stress concentration on the rotor bar.
mm Gradually lower the conductor height from the position corresponding to the protruding part toward the tip of the rotor bar, and cut out so that the remaining cutout part forms a gentle arc on the side surface, then shrink when inserted into the rotor core. A notch is made up to the tip end with a constant conductor height (dimension corresponding to A in FIG. 1) such that the outer diameter of the ring is smaller than the outer diameter of the rotor core. That is, the dimension corresponding to A in FIG. 1 shows a case where the cylindrical shrink ring is cut out by reducing the portion corresponding to the thickness of the cylindrical portion from the conductor height of the rotor bar.

Next, a notch which is an essential part of the present invention is formed in the tip portion of the rotor bar. That is, the already notched portion (dimension corresponding to A in FIG. 1) is further cut by a few mm to reduce the conductor height to a constant height (dimension equivalent to C in FIG. 1), and the notch length is It is formed to be about ½ of the width of the end ring (the size corresponding to B in FIG. 1). After that, the edge of the conductor, which corresponds to the portion protruding from the side surface of the rotor core and is formed at a right angle in the conductor cross section, is chamfered by about 1C, and the preparatory processing of the rotor bar is completed.

On the other hand, on the side surface of the cylindrical end ring 32, which is an essential part of the present invention, an annular groove having a rectangular cross section is formed in order to insert the notch remaining portion of the tip end portion of the rotor bar of the essential part of the present invention. To provide. The annular groove has an inner diameter that matches the outer diameter dimension of the rotor bar tip when the rotor bar is inserted into the rotor core. The groove width is the conductor height dimension of the rotor bar tip (corresponding to C in FIG. 1). The groove depth is about 1/2 of the width of the end ring (the size corresponding to B in FIG. 1).

Here, it is not always necessary to provide a groove on the side surface of the end ring, and the gist of the present invention is that the outer periphery of the joint between the end ring and the rotor bar is covered with the end ring, and the outer periphery of this end ring is covered. It suffices that the shrink ring can be fitted over the outer ring. Therefore, the flange-shaped end ring 42 as shown in FIG. 2 does not cause any problem. The outer peripheral surface of the end ring on which the shrink ring is fitted is machined so that the dimensional tolerance is JIS class 6 or so, and the preparation of the end ring is completed.

The rotor bar and the end ring that have been preliminarily processed are used to assemble and set the rotor core. That is,
The rotor bar is inserted into the rotor core, the tip of the rotor bar is covered with an annular groove or flange provided on the side surface of the end ring, and the abutting portions of the rotor bar tip and the end ring are brazed together and joined. . After that, the outer diameter dimension of the shrink ring mounting surface of the end ring is measured, and if there is no abnormality according to the design, the shrink ring is fitted on the outside and the work is finished.

If the outer diameter of the end ring is measured,
If there is a dimensional abnormality such as deformation due to the effect of brazing, the outer diameter is reprocessed to deal with it, but there is no generation of dust due to machining waste as in the conventional example, and continuous thread-like machining waste is generated. The cleaning of the processing waste does not require as much working time as in the conventional case.

[0022]

Since the present invention has the above-described structure, conventionally, when the shrink ring is externally fitted, the rotor bar is inserted into the rotor core, and after joining the end ring, the joining portion is machined. No longer needed,
Therefore, there is an effect that the cleaning work of cutting dust and dust generated due to the machining is unnecessary, but instead, the cutting work for lowering the conductor height at the tip of the rotor bar and the both ends of this rotor bar are performed. It is necessary to perform an operation of providing an annular groove or a flange shape on the side surface of the end ring corresponding to the portion covering the portion. However, these operations do not require special equipment or technology, and the processing can be performed with the material of the parts alone, so that the processing process can be easily automated and a precise product with no variations is produced, resulting in a highly accurate finish. The size is easily obtained, and the large-scale production of the squirrel cage rotor having such a structure can be efficiently and easily performed in a short time.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional example.

FIG. 4 is a cross-sectional view of another conventional example.

FIG. 5 is a view as seen from an arrow in FIG.

FIG. 6 is a sectional view of a conventional example.

[Explanation of symbols] 1 rotor bar 2 end ring 3 shrink ring 4 rotor core 11 rotor bar 12 end ring 13 shrink ring 21 rotor bar 22 end ring 23 shrink ring 31 rotor bar 32 end ring 33 shrink ring 42 end ring

Claims (1)

[Claims] 1. A squirrel-cage rotor comprising an end ring joined to a tip of a rotor bar protruding from a side surface of a rotor core, and a shrink ring fitted on an outer periphery of the joined portion.
The end ring joined to the tip of the rotor bar is formed to have a cylindrical portion that covers the joined portion from the outer circumference, and a shrink ring is externally fitted to the outer circumference of the cylindrical portion. Rotor.