JPS6029334Y2 - Electric motor - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a motor equipped with a conducting wire for electrically detecting damage to an end ring in a squirrel cage rotor.

Conventionally, an electric motor equipped with a squirrel cage rotor has a configuration as shown in FIG.

In FIG. 1, a stator core 1 has a stator coil 2 and is opposed to a squirrel cage rotor.

The squirrel cage rotor includes a rotor core 3, bars 4 inserted into slots provided in the rotor core 3, and an end ring 5 connected to one end of each bar 4 by brazing or the like. A rotating shaft 6 passes through the center of the rotor core 3.

The rotor core 3 is fixed onto the rotating shaft 6 by a clamper 7.

In such a configuration, when the electric motor is started, a large mechanical stress is applied to the filler metal portion 4a between the bar 4 and the end ring 5, and during operation of the electric motor, heat generation causes the filler metal portion to A thermal stress is applied to 4a.

If such mechanical and thermal stresses are repeatedly applied, the brazing material portion 4a will eventually break due to deformation and metal fatigue.Normally, the medium to large capacity rotor core 3 has a stress of 50 to 1
00 bars 4 are embedded, but if one of them breaks from the end ring 5 as described above, current will no longer flow through the broken bar 4, and a corresponding current will flow through the adjacent bar 4. flows into.

As a result, the adjacent bars 4 generate more heat, and the brazing filler metal portion 4a also breaks.

In this way, the brazing material portions 4a of each bar 4 are broken one after another, and the end rings 5 that have been broken from all the bars 4 collide with the stator coil 2, leading to its destruction as well.

Therefore, it is desirable that the breakage of the brazing material connecting the rotor bar and end ring, which causes such a serious accident, be detected at an early stage.

However, conventional electric motors have the disadvantage that breakage of the brazing material cannot be externally detected at an early stage, leading to serious accidents.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it uses a conducting wire to detect a break through the brazing metal part that connects the rotor bar and the end ring. It is an object of the present invention to provide an electric motor that can externally detect a break in a brazing filler metal part at an early stage so that when a breakage occurs in the brazing filler metal part, a conductive wire is cut together with the breakage.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of the main parts of the electric motor according to this invention.

In FIG. 2, a conductor 10 constituting a break detection circuit is connected to a transducer 11 attached to the inner circumference of the end ring 5. In FIG.

This converter 11 has an indicator light inside to indicate that the circuit to which the conductor 10 is connected is operating normally by the electromotive force induced in the conductor 10, and is a device that turns on the indicator light.

The conductor 10 is led along the side of the end ring 5 to the outer circumference of the rotor and wired to the first bar 4 end ring 5.

The conductor 10 is then routed through the slot 12 on the rotor core 3 to the adjacent bar 4 and end ring 5, as shown in FIG. It returns again to the same position via the first bar 4 and is wired to be connected to the transducer 11.

Furthermore, the conducting wire 10 is fixed to the bar 4, the end ring 5, and the slot 12 of the rotor core 3 using an epoxy adhesive or the like, and is electrically insulated from these by the insulating coating.

Next, its operation will be explained.

Since the conducting wire 10 is disposed on the outer surface of the rotor, the rotation of the rotor cuts the magnetic flux generated by the stator, and an electromotive force is induced in the conducting wire 10.

This induced electromotive force can be used to power the converter 11 and turn on the indicator light.

This indicator light is built into the converter and placed in a position where it can be easily observed from the outside.

This indicator light lights up in the state of strain field, so it acts like a ring of lights even during rotation, and while it can be observed from the outside through a peephole, it can also be used to detect abnormal deformation or breakage of the bar or end ring. As described above, since the conductor 10 is broken midway, no power is supplied to the converter, and the indicator light goes out to notify the converter of an abnormality.

Although the breakage of the conductive wire 10 mainly occurs at the soldered portion 4a, it may also be due to an abnormality in other parts.

Further, the wiring route of the conducting wire 10 is not limited to that of the embodiment described above.

In addition, a storage battery is built into the converter, and when power is not supplied from the conductor 10 due to an abnormality, this storage battery is activated, and when power is normally supplied from the conductor 10, a blue display is displayed. It is possible to display a red display when an abnormality occurs, or to turn off the light only when an abnormality occurs, without turning anything on during normal conditions.

It is also possible to detect abnormal lighting with a phototube and use it as a signal for a motor trip.

As described above, according to this invention, a conductive wire is laid on the surface of the bar, and the electromotive force induced in the conductor is converted to indicate normal or abnormal, so that it can be used at the brazing part of a rotating electric motor. Broken bars and end rings can be easily detected, and abnormalities in the motor can be detected at an early stage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional electric motor, FIG. 2 is a sectional view showing an embodiment of this invention, and FIG. 3 is a plan view of the rotor core portion shown in FIG. 2. In the figure, 1 is a stator core, 2 is a stator coil, 3 is a rotor core, 4 is a bar, 5 is an end ring, 6 is a rotating shaft, 7 is a rotor clamper, 10 is a conductor, and 11 is a converter. be. Note that the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] In an electric motor equipped with an end ring that short-circuits bars inserted into a plurality of slots formed in a rotor core at one end thereof, the end ring is provided along the bar, and through the connection between the bar and the end ring, and fixed on this connection,
It includes a conductor made of a thin wire that breaks at the same time when the connection part breaks, converts the induced electromotive force due to the rotation of the conductor forming a closed circuit, and converts the change in the induced electromotive force due to the breakage of the conductor into a display. An electric motor characterized by having a device mounted on a rotor.