JP3815367B2 - Rotating machine rotor regeneration method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotor regeneration method for a rotating electrical machine, and more particularly, to a rotor regeneration method for a rotating electrical machine suitable for a varnish filled between a rotor bar and a slot, such as a rotor of a main motor for a vehicle. .
[0002]
[Prior art]
In general, most of rotors for induction motors for vehicles are impregnated with varnish for reasons such as strengthening the fixing strength of the rotor bar and preventing oxidation of the rotor.
[0003]
The varnish is filled in the slot so as to close the gap between the rotor bar and the slot, and assists the support of the rotor bar to the rotor core. However, due to aging and deterioration of the varnish due to the high temperature of the rotor due to overload of the main motor, the amount of varnish in the slot is reduced and the filling rate of the varnish is reduced, and the rotor bar holding effect on the rotor core The torsional natural frequency of the inertial system in which the rotor core and the short-circuit ring are inertial bodies and the rotor bar is a spring is gradually reduced.
[0004]
In recent years, for vehicle induction motors, speed control by controlling inverter power supply voltage and frequency has become mainstream due to the development of electronic technology. The terminal voltage of the inverter includes a harmonic component that is an integral multiple of the fundamental wave in addition to the sine wave component that is the fundamental wave when controlling the normal power supply voltage and frequency. Therefore, in addition to the torque due to the fundamental wave component, the main motor also has a so-called pulsating torque generated by the harmonic component of the power supply, and the influence of resonance using this pulsating torque as the excitation source is the torsional natural vibration of the rotor. It becomes remarkable as the number decreases, and in the worst case, the rotor bar may be broken. Further, there is a need for a method for extending the life of a rotor in which the torsional natural frequency is lowered and the influence of resonance is becoming prominent or the influence is becoming prominent.
[0005]
[Problems to be solved by the invention]
As a method for extending the life of the rotor in which the torsional natural frequency is decreasing and the influence of resonance is becoming remarkable or the influence is becoming remarkable, varnish reimpregnation in which varnish is reinjected into the rotor can be considered. Varnish re-impregnation is a relatively common technique for extending the life of insulation such as stator windings, rotor windings of DC machines, and rotor windings of induction machines of wound rotors. In the case of a driving bar type induction machine using a bar as a rotor conductor, the conventional varnish re-impregnation method has a problem of varnish removal at the previous impregnation.
[0006]
That is, if the varnish removal at the previous impregnation is not performed, the old varnish prevents impregnation of the new varnish, and even if the natural frequency temporarily recovers to the level of the new product, the deteriorated old varnish remains partially. Therefore, it has been found that the decrease in natural frequency tends to be greater than the decrease in rotor at the time of new production, and the effect of life extension is low. That is, it is required to remove the old varnish that has deteriorated as much as possible at the time of re-impregnation.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and the object of the present invention is to regenerate the rotor of a rotating electrical machine capable of easily removing old varnish, effectively re-impregnating varnish, and extending the life of the rotor. Is in providing a way.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a plurality of slots are formed in the outer peripheral portion of the rotor core so as to be continuous in the axial direction and at a predetermined interval in the circumferential direction. A rotor of a rotating electrical machine in which the end of the rotor bar is electrically joined by a short-circuited ring, varnish is filled between the rotor bar and the slot, and both are fixed, The rotor that has been used for a long time is stored in a furnace, heat-treated at 450 to 600 ° C. to remove the previously impregnated varnish , the rotor is then taken out of the furnace and cooled, and then a new one is added. The varnish is re-impregnated and filled between the rotor bar and the slot.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 shows a rotor structure of a vehicle induction motor to which the present invention is applied.
[0010]
In the figure, reference numeral 1 denotes a rotor core, and a plurality of axially continuous slots 7 are formed on the outer peripheral portion of the rotor core 1 at predetermined intervals in the circumferential direction. The bar 2 is stored.
[0011]
The ends of the rotor bar 2 are joined by a short-circuit ring 3, and the rotor bars 2 are electrically short-circuited. The short ring 3 is fitted with a holding ring 4 that suppresses the centrifugal force caused by the rotation. A rotating shaft 6 is provided on the central axis of the rotor core 1. Since the rotor core 1 is generally formed of a laminated silicon steel plate, the rotor core 1 is clamped by core pressers 5 on both sides of the rotor core 1.
[0012]
As shown in FIG. 2, the slot 7 is slightly larger than the rotor bar 2 due to the insertion of the rotor bar 2, and as a result, a gap 8 is formed between the rotor bar 2 and the slot 7. Then, the varnish is impregnated with the rotor 9 to fill the gap 8, and the gap 8 is reduced equivalently, so that the fixing of the rotor bar 2 in the slot 7 is strengthened.
[0013]
The varnish sufficiently filled in the gap 8 at the time of new production gradually decreases due to deterioration due to heating of the rotor 9 and wear due to vibration. Therefore, the gap 8 is equivalently increased and the support of the rotor bar 2 in the slot 7 is relaxed. As the support of the rotor 9 in the slot 7 is relaxed, the torsional natural frequency of the rotor of (a) mode 1 and (b) mode 2 shown in FIG. 3 decreases, and the harmonic pulsation torque of the inverter The effect of resonance using the component as the excitation source becomes significant. Since the influence of resonance becomes significant, there are cases in which excessive stress is repeatedly applied to the rotor bar 2 and the rotor bar 2 is broken.
[0014]
Therefore, the cause of the decrease in the torsional natural frequency is a decrease and deterioration of the varnish filled in the slot 7 in the gap 8. Implementing varnish reimpregnation is simple and effective in extending the life of the rotor. Specific examples of the varnish re-impregnation method are shown below.
1. Remove the rotor from the main motor and remove bearings, fan and other accessories as necessary.
2. The rotor is placed in a high temperature furnace capable of maintaining a temperature of about 450 ° C to 600 ° C.
3. The varnish is burned for several hours while maintaining the temperature of 2 above.
4). After the varnish is sufficiently burned by the above 3, the rotor is taken out of the furnace and cooled.
5). The rotor after varnish combustion is restored to the same gap as the rotor when newly manufactured, and varnish can be re-impregnated by any method.
[0015]
In this way, it is possible to easily remove old deteriorated varnish that prevents re-impregnation and reduces the life extension effect after re-impregnation, and the slots and rotors necessary for effective varnish re-impregnation. The gap of the bar can be secured as in the new product.
[0016]
FIG. 4 shows the results of confirming the change over time in the natural frequency of torsion when the old varnish was removed by heating before re-impregnation in this example and when the old varnish was re-impregnated without removing the old varnish. . As is clear from the figure, the rotor re-impregnated while leaving the old varnish clearly has a faster rate of decrease in the torsional natural frequency than that of the newly manufactured rotor. The torsional natural frequency tends to decrease in the same manner as when newly manufactured, and it can be seen that this method is effective for recovery of the torsional natural frequency by varnish reimpregnation.
[0017]
【The invention's effect】
According to the rotor regeneration method for a rotating electrical machine of the present invention described above, there is an effect that old varnish can be easily removed and varnish re-impregnation can be performed effectively, and the life of the rotor can be extended.
[Brief description of the drawings]
FIG. 1 is a front view of an upper half showing a rotor of a motor for a vehicle to which an embodiment of a rotor regeneration method for a rotating electrical machine according to the present invention is applied.
2 is a detailed cross-sectional view showing an arrangement relationship between slots and rotor bars in FIG. 1; FIG.
FIG. 3 is a diagram showing a mode in which the torsional natural vibration of the rotor decreases.
FIG. 4 shows the results of confirming the change over time in the natural frequency of torsion when the old varnish was removed by heating before re-impregnation in the present invention and when the old varnish was re-impregnated without removing the conventional old varnish. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotor core, 2 ... Rotor bar, 3 ... Short-circuit ring, 4 ... Holding ring, 5 ... Iron core presser, 6 ... Rotating shaft, 7 ... Slot, 8 ... Gap, 9 ... Rotor.

Claims (1)

A plurality of slots are formed in the outer peripheral portion of the rotor core in the axial direction and at predetermined intervals in the circumferential direction, and a rotor bar is accommodated in each slot, and an end portion of the rotor bar Is electrically connected by a short-circuit ring, and is a rotor of a rotating electrical machine in which varnish is filled between the rotor bar and the slot and both are fixed,
The rotor that has been used for a long time is stored in a furnace, heat-treated at 450 to 600 ° C. to remove the previously impregnated varnish , the rotor is then taken out of the furnace and cooled, and then a new one is added. A method of regenerating a rotor of a rotating electric machine, comprising re-impregnating varnish and filling between the rotor bar and the slot.

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