JP3752781B2 - Cage type rotating electrical machine rotor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a squirrel-cage rotor of an induction motor, and more particularly to a squirrel-cage rotor manufactured by aluminum die casting.
[0002]
[Prior art]
Conventionally, a cage rotor of this type will be described with reference to FIGS.
[0003]
In the squirrel-cage induction motor, the rotor is formed by stacking a plurality of cores 1 processed by punching or the like so as to have a plurality of slots 2 as shown in FIG. As shown in the figure, a conductor bar 3 and ring-shaped end rings 4 and cooling fins 5 are integrally formed in an aluminum die casting in a slot 2 to form a squirrel-cage winding.
[0004]
Conventionally, in a rotor having such a structure, cores 1 having the same shape are laminated, and the slot shape is equal in the axial direction (Japanese Patent Laid-Open No. 3-198641).
[0005]
[Problems to be solved by the invention]
By the way, in an induction motor, in a normal start, a current starts to flow through the aluminum conductor, so that a sudden temperature rise occurs in the conductor bar 3 and the end ring 4, and at the same time, centrifugal force due to rotation is loaded. In an abnormally activated state where the rotating shaft is constrained, there is no centrifugal force load due to rotation, but the time during which a large current flows through the aluminum conductor is longer than in normal starting, and the conductor bar 3 and end ring 4 A large temperature rise occurs. The deformation state of both of these is shown in FIG. FIG. 4A shows an initial state (before starting), and FIG. 4B shows a deformation state after starting. First, the conductor bar expands in the axial direction due to thermal deformation accompanying temperature rise. Further, the end ring expands in the radial direction due to a temperature rise, and at the same time as starting with rotational deformation, expansion in the radial direction due to centrifugal force occurs simultaneously. When the conductor bar expands and a gap is generated between the end ring and the core 6, the end ring can be deformed to bend at an angle in the axial direction as shown in FIG. Therefore, in order to absorb the expansion deformation of the end ring, the conductor bar is pulled in the end ring expansion direction, and the conductor bar is bent and deformed as shown in FIG. Due to this bending deformation, a stress as shown in FIG. 6 is generated on the bottom surface 7 of the conductor bar, and a large tensile stress is generated at the end ring root 8 of the bar. Since this tensile load is repeatedly applied by repeated starting and stopping and abnormal starting, it causes fatigue breakage of the conductor bar.
[0006]
The object of the present invention is to provide a cage rotor having high fatigue strength by reducing the high tensile stress generated in the conductor bar and the end ring root portion 8.
[0007]
[Means for Solving the Problems]
A core having a slot opened in the shape of a conductor bar is laminated on the outer periphery of the above-described circular thin plate, and a conductor bar, a ring-shaped end ring and cooling fins are formed in the slot by integral casting. In the rotor of a cage type rotating electrical machine,
In order to constrain the deformation of the conductor bar in the axial direction to the core, a squirrel-cage electric rotating machine having a structure in which the conductor bar and the core are provided with protrusions and recesses and the protrusions of the conductor bar are tapered. This can be achieved by a rotor .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. 1 and 6 to 11.
[0010]
In FIG. 1, a slit is enlarged in the vicinity of the end ring, and one conductor 9 is provided on the conductor bar. FIG. 5 shows the deformation state at this time. The convex portion 9 restrains the axial deformation of the conductor bar by the core, and no gap is formed between the end ring and the core. Therefore, bending deformation of the conductor bar does not occur, and the base portion 8 of the bar and the end ring is not in a tensile state. The stress distribution at this time is shown in FIG. The tensile stress at the base is reduced, and the deflection of the end ring is constrained to generate compressive stress.
[0011]
The advantage of this structure over other embodiments is that when punching the core, several cores are manufactured with a punching die with a slightly larger slit shape, and these larger slit shapes are formed when the cores are stacked. The convex portion of the conductor bar can be easily created simply by stacking the core having the layer on the layer forming the convex portion of the conductor bar and integrally shaping with aluminum die casting. However, in this case, there is a problem that stress concentration also occurs at the locations corresponding to the convex portion angles 10 and 11, and the compressive stress increases.
[0012]
FIG. 7 shows a taper shape on one side of the convex portion 9 of the previous embodiment, which restrains the axial expansion of the bar as in the previous embodiment and can suppress the generation of tensile stress at the base portion. Moreover, the stress concentration which arises in a corner | angular part can be prevented by tapering a convex part with respect to all the Examples. However, it is difficult to provide such a taper only by the punching method as in the previous embodiment, and machining is required at the time of stacking the cores, which increases the number of steps.
[0013]
FIG. 8 shows the same taper on both sides of the convex portion as in FIG. In addition, FIG. 9 has R at the corner of the convex portion. These reduce the stress at the stress concentration portion of the corner portion in the embodiment of FIG. 1 as in the embodiment of FIG. 7, but require machining and increase the number of steps.
[0014]
FIG. 10 shows a plurality of convex portions. The root stress reduction effect is the same as that of the above embodiment, and the stress concentration in the embodiment of FIG. 1 can be dispersed by using a plurality of convex portions. In addition, processing can be performed only by stacking cores having different slit sizes alternately and die casting. FIG. 11 shows an embodiment in which only the lower side of the bar is convex.
[0015]
Thus, since it aims at constraining the axial deformation | transformation of a conductor bar to a core, it is good also considering a conductor bar as a concave shape contrary to an Example.
[0016]
【The invention's effect】
As is clear from the above description, according to the present invention, by providing the conductor bar with a convex portion or a concave portion that restricts the axial deformation of the conductor bar to the core, the base of the bar and end ring of the conductor bar is provided. High tensile stress generated in the part can be reduced, and a cage rotor with high fatigue strength can be provided.
[Brief description of the drawings]
FIG. 1 is a sectional view of a rotor in one embodiment of the present invention.
FIG. 2 is a diagram showing a rotor structure that is an embodiment of the present invention.
FIG. 3 is a cross-sectional view of a rotor core that is an embodiment of the present invention.
4A and 4B are cross-sectional views showing a conventional structure.
5A and 5B are cross-sectional views of a rotor according to an embodiment of the present invention.
FIG. 6 is a characteristic diagram comparing the stress distribution at the bottom of the conductor bar between the conventional structure and the inventive structure.
FIG. 7 is a cross-sectional view of a rotor showing some embodiments of the present invention.
FIG. 8 is a cross-sectional view of a rotor showing some embodiments of the present invention.
FIG. 9 is a sectional view of a rotor showing some embodiments of the present invention.
FIG. 10 is a cross-sectional view of a rotor showing some embodiments of the present invention.
FIG. 11 is a cross-sectional view of a rotor showing some embodiments of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Core, 2 ... Slit, 3 ... Conductor bar, 4 ... End ring, 5 ... Cooling fin, 6 ... Gap between end ring and core, 7 ... Bottom surface of conductor bar, 8 ... Base part of conductor bar and end ring, 9 ... convex part, 10 ... convex part angle 1, 11 ... convex part angle 2.

Claims (1)

A cage type in which a core having a slot opened in the shape of a conductor bar is laminated on the outer periphery of a circular thin plate, and a conductor bar, a ring-shaped end ring and cooling fins are formed by integral casting in the slot. In the rotor of a rotating electrical machine,
In order to constrain the deformation of the conductor bar in the axial direction to the core, a squirrel-cage electric rotating machine having a structure in which the conductor bar and the core are provided with protrusions and recesses and the protrusions of the conductor bar are tapered. Rotor.

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