JPH04197052A - Motor - Google Patents

Abstract

PURPOSE:To prevent leakage magnetic flux to a housing and to prevent a decrease in the performance of a motor and an increase in temperature by providing a rib in contact with the inner periphery of a housing on the outer periphery of a stator core, and forming the rib by deviating a core from a maximum magnetomotive force direction generated by a stator winding. CONSTITUTION:A motor 2 is composed of a 3-phase 2-pole brushless motor, a stator core 26 has 12 slots 26a, and radial ribs 27a, 27b, 27c are formed on the outer periphery. Since they are provided by deviating a core from a maximum magnetomotive force generating direction, a leakage magnetic flux does not flow to a housing 25, and problems of a temperature rise, a decrease in characteristic can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improving performance in electric motors.

[Conventional technology]

In conventional electric motors, as described in Utility Model Publication No. 63-88073, the outer periphery of the stator core is formed into a substantially circular shape, and almost the entire outer periphery is press-fitted, abutted, or fitted into the housing. It had become.

[Problem to be solved by the invention]

In the case of a housing formed of a magnetic material, leakage magnetic flux from the stator to the housing occurs in the above conventional technology, resulting in deterioration of various motor characteristics due to insufficient magnetomotive force on the stator side and temperature rise due to eddy current generated in the housing. There was a risk that it would cause An object of the present invention is to prevent leakage of magnetic flux to the housing, thereby preventing a decrease in motor performance and a rise in temperature.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a rib on the outer periphery of the stator core that comes into contact with the inner periphery of the housing. It is formed.

[Effect]

In the stator, the magnetic flux density of the stator core is maximum in the direction of the maximum magnetomotive force due to the stator windings, so magnetic flux is most likely to leak in this direction.

In addition, in the present invention, magnetic flux easily passes through the areas where the stator core and the housing are in contact, which is likely to cause leakage.
By providing radial ribs on the outer periphery of the stator, the contact area between the stator core and the housing is reduced, and leakage magnetic flux from the stator to the housing is reduced. Furthermore, by shifting the center of the rib from the direction of the maximum magnetomotive force of the stator, leakage magnetic flux is reduced, thereby preventing a decrease in the performance of the motor and an increase in the temperature of the housing.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of application to an electric blower. The electric blower 1 includes an electric motor section 2 consisting of a brushless motor, a centrifugal fan 31 . The air blower section 3 is composed of a fixed guide vane 32 and a casing 33 that covers it.

The exhaust flow discharged from the centrifugal fan 31 is transferred to the fixed guide vane 32.
After cooling the inside of the motor section 2, it is discharged to the outside through the exhaust hole 25a of the housing 25.

The electric motor section 2 includes a rotor 22 having a permanent magnet 21 and a stator 24 having a stator winding 23 wound around the outer periphery of the rotor 22, and is housed in a housing 25.

The electric motor section 2 is composed of a three-phase, two-pole brushless motor, and as shown in FIG. 2, the stator core 26 has 12
radial ribs 27 on the outer periphery.
a, b, c, d are formed. The housing 25 has a rib 27a on its inner peripheral surface.

The outer circumferences of b, c, and d are press-fitted and fixed. A gap 28 between the housing 25 and the outer periphery of the stator core 26 forms a flow path for cooling air from the centrifugal fan 31.

As shown in FIG. 3, the stator winding 23 is wound with three phases A, B, and C. When the rotor 22 rotates, the waveform of the induced voltage generated between each wire is as shown in FIG. It will be like this.

Here, when current flows through each phase as shown in FIG. 3, the composite magnetic flux of the three phases is generated in the direction of the arrow, that is, the direction of the arrow becomes the maximum magnetomotive force. In the waveform of FIG. 4, this is the position indicated by the arrow in the figure, and it can be seen from the figure that it occurs every 60 degrees.

Further, the magnetic flux density of the stator core 26 at the position where the maximum magnetomotive force is generated is maximum, and the magnetic flux flows as shown in FIG. 5.

At this time, in FIG. 6, the rib 27 is directed in the direction of the generated magnetic flux.
In this case, since the magnetic flux density is maximum, the magnetic flux leaks into the housing 25 through the rib 27a, generating eddy currents in the housing 25, increasing the temperature, and causing insufficient cooling. This becomes a problem.

Further, due to leakage magnetic flux, the magnetomotive force at the stator 24 is insufficient, resulting in a problem that various characteristics of the motor section 2 are deteriorated.

In the present invention, as shown in FIG. 5, since the ribs 27a, b, c, and d are provided with their centers offset from the direction in which the maximum magnetomotive force is generated, leakage magnetic flux flows into the housing 25 as described above. This prevents problems such as temperature rise and characteristic deterioration.

〔Effect of the invention〕

According to the present invention, since leakage magnetic flux to the housing 25 can be reduced, the electric motor section 2 due to temperature rise of the housing 25 can be reduced.
It is possible to prevent deterioration of various characteristics of the electric motor section 2 due to insufficient cooling of the stator 24 and insufficient magnetomotive force of the stator 24.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of an electric blower showing an embodiment of the present invention, Fig. 2 is a cross-sectional view of the electric blower, and Fig. 3 shows the direction of current in the stator winding and the direction of the generated magnetic flux. A cross-sectional view of the electric motor section, FIG. 4 is a waveform diagram of the induced voltage generated between each winding when the rotor 22 rotates, and FIG. 5 is an embodiment of the present invention.
A diagram showing the flow of magnetic flux, FIG. 6 is a reference diagram showing the flow of magnetic flux. 22... Rotor, 23... Stator winding, 24
...Stator, 25...Housing, 26...Stator core, 1st opening 2nd opening qc 2nd opening z'tc 4th - 5th opening

Claims (1)

[Claims] 1. In an electric motor in which a stator is disposed on the outer circumferential side of a rotor, and the rotor and stator are housed in a housing, a plurality of radial ribs that fit into the inner circumference of the housing are provided. An electric motor characterized in that the rib is provided on the outer periphery of a stator, and the center of the rib is offset from an extension line of the center of maximum magnetomotive force formed by the stator winding. 2. The electric motor according to claim 1, wherein a gap between the inner periphery of the housing and the outer periphery of the stator is configured as a cooling air flow path. 3. The electric motor according to claim 2, wherein the electric motor is constituted by a brushless motor.