JP2639011B2 - Variable reluctance motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a variable reluctance motor.

[Related Art] Conventionally, a variable reluctance motor has a stator in which coils are respectively wound around a plurality of magnetic pole protrusions provided on an inner peripheral portion, a rotatable support in a space in the stator, and an outer peripheral portion. And a rotor having a plurality of magnetic pole projections. The operation principle of this motor will be described with reference to FIG. Now, when rotating the stator S
When the coil C is excited when the rotor R is positioned at the phase angle θ _A on the advance side shown by the solid line, the magnetic path is expanded in the rotor R to reduce the magnetic resistance and the force in the direction of reducing the magnetic flux density. Causes a rotational torque in the direction indicated by the arrow in FIG.

Since such a state in which the magnetic resistance changes appears as a change in the self-inductance of the coil C, when the coil C is energized in the inductance increasing region, a positive rotational torque is generated in the rotor R. Further, when the rotor R with respect to the stator S is located in the phase angle theta _B the retard side indicated by a broken line, energizing the coil C when self-inductance of the coil C has been changed to phenomena direction by rotation of the rotor R , A negative rotation torque (braking torque) is generated in the rotor R. As described above, the variable reluctance motor generates a positive or negative rotation torque by controlling the energization of the coil C at a predetermined rotor R position, and the torque T is expressed by the following equation (1). .

T∝KIdL / dθ (1) L: Inkance of coil C θ: Phase angle of rotor R I: Current flowing through coil K: Constant In a variable reluctance motor having such a torque characteristic, the static reluctance of each phase is The relationship between the torque and the phase angle θ when the rotor R is gradually rotated with a constant current flowing through the coil C is found to be 5th.
It looks like the figure. As can be seen from this figure, each phase φ ₁ to φ ₁
The static torque of No. ₄ sharply increases and decreases from near 0, and deviates greatly from the sine wave. For this reason, the output torque of the motor, which is the sum of the static torques of the phases φ _{1 to} φ ₄ , also has a considerably large pulsation, which causes vibration. This pulsation can be reduced by controlling the current waveform to the coil of each phase.However, in order to perform appropriate control, it is necessary to create a complicated current waveform by an electronic circuit or the like. Due to the large inductance of C, there is a problem that it is not easy to generate an initial current waveform due to the time constant, especially at high speed rotation.

As a method for coping with such a problem, there is a method of making a static torque waveform as close as possible to a sine wave when a constant current is supplied to a coil. For example, a groove (skew) inclined with respect to an output shaft on an outer periphery of a rotor, Alternatively, the end of the magnetic pole protrusion of the rotor is shaved to widen the air gap, thereby reducing the change in self-inductance and reducing pulsation.

However, in the former case where the skew is provided, a force is generated in the thrust direction, and a large load is applied to bearings and the like.
Further, in the case of providing the latter gap, an extra magnetomotive force is required to widen the air gap, and there is a problem that the efficiency is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the related art, and an object of the present invention is to provide a variable reluctance motor having excellent pulsation and excellent torque characteristics.

[Means for Solving the Problems] A variable reluctance motor according to the present invention, which has been made to solve the above problems, includes a stator having coils wound around a plurality of magnetic pole protrusions provided on an inner peripheral portion, and an outer peripheral portion. A rotor provided with a plurality of magnetic pole projections, and a magnetic characteristic buffer member disposed between the respective magnetic pole projections of the stator and made of a magnetic material or a semi-magnetic material. An inner peripheral end face and an inner peripheral end face of the magnetic pole projection of the stator are formed to have the same inner diameter.

[Operation] The variable reluctance motor according to the present invention has a structure in which when the magnetic pole protrusion of the rotor approaches a predetermined position with respect to the magnetic pole protrusion of the stator, that is, when the inductance of the coil increases in the positive direction, By energizing a predetermined coil, a rotational torque is generated in the rotor.

In addition, the motor has a magnetic property buffering member disposed between the magnetic pole protrusions of the stator, and this member is slightly magnetized when the coil is excited, so that the inductance of the coil during driving is reduced. Acts to be changed gradually. In addition, the inner peripheral end surface of the magnetic characteristic buffer member is formed to have a constant inner diameter, and the inner peripheral end surface of the magnetic pole projection of the stator is formed to have the same diameter as this member. . That is, the magnetic pole protrusion and the magnetic property buffering member form an inner peripheral surface with no gap. As a result, the magnetic resistance when the rotor rotates does not change drastically as the air gap distance increases or decreases unlike the conventional variable reluctance motor. Accordingly, the static torque generated in response to the change does not show a rapid change, approaches a sine wave, and therefore, it is easy to reduce the pulsation in the total torque obtained by summing the phases during the rotation driving.

Example An example of the present invention will be described below.

FIG. 1 shows a half-side sectional view of a variable reluctance motor. In FIG. 1, reference numeral 1 denotes a cylindrical stator made of a laminated iron core. An eight-pole magnetic pole projection 3 around which a coil 2 is wound is provided on an inner peripheral portion of the stator 1. on the other hand,
An output shaft 6 and the output shaft 6 are provided in a cylindrical space in the stator 1.
And a rotor core 8 supported by the rotor core 7 is supported. The rotor core 7 has six magnetic pole projections 9 on the outer periphery.
Are formed by stacking iron core forming members 10 having

Also, on both sides of the tip of the magnetic pole protrusion 3 of the stator 1,
As shown in the figure, engagement grooves 13a and 13b are formed along the axial direction. Further, a magnetic characteristic buffering member 14 formed of a magnetic material or a semi-magnetic material is provided between the magnetic pole projections 3. That is, the magnetic characteristic buffering member 14 has step portions 15a and 15b on both sides thereof, is fitted and mounted in the engaging grooves 13a and 13b, and has a coil 2 at its inner end surface.
Is in contact with the end of The magnetic characteristic buffer member 14 is made of a magnetic material obtained by resin-molding iron, ferrite, or iron powder, and has a magnetic strength of 2 to 3 to 10 in saturation magnetic flux density.
Adjusted to kilogauss. Magnetic property buffer 14
In order to mount the coil 2, the coil 2
After mounting, the steps 15a and 15b are aligned with the engagement grooves 13a and 13b, and this is slid. The inner surface (the surface facing the rotor 8) of the magnetic characteristic buffering member 14 is formed so as to be located on substantially the same circumference as the inner diameter of the magnetic pole projection 3 of the stator 1, and thereby the magnetic characteristics described later will be described. The effect of the characteristics is enhanced.

Although not shown, a rotating disk having a slit on the outer periphery is fixed to the output shaft 6, and a photo-interrupter for detecting the slit is provided opposite to the rotating disk. The rotating disk and the photointerrupter constitute a rotation position detector, and the position of each magnetic pole projection 3 with respect to the rotor 8 can be obtained based on a detection signal from this detector.

 Next, the operation of the motor will be described.

This motor is controlled based on the principle described in the related art. For example, when the magnetic pole projection 9a of the rotor 8 shown in FIG. 1 approaches the magnetic pole projection 3a of the stator 1 (in a region where the inductance increases) during driving, this state is detected by a rotational position detector, and this detection signal An energization command to the coil 2a is output from the electronic control unit (not shown) based on the
As a result, a positive rotation torque is generated in the rotor 8. When the magnetic pole projection 9a of the rotor 8 moves away from the magnetic pole projection 3a of the stator 1 (in a region where the inductance decreases),
The energization of the coil 2a is stopped so that a negative rotation torque is not generated and the rotation torque in the positive direction is maintained. Further, at the time of braking, when the magnetic pole projection 9a of the rotor 8 moves away from the magnetic pole projection 3a of the stator 1, the coil 2a is energized to generate a braking force.

Next, in order to examine the effect of improving the torque characteristics by the magnetic characteristic buffering member 14 provided in the present motor, the static torque characteristics of the motor were measured, that is, the rotor 8 was gradually moved while a constant current was passed through the coil 2. FIG. 3 was obtained as a result of measuring the torque when rotating. As is apparent from the drawing, according to the motor of the present embodiment, compared with the conventional motor shown in FIG.
The change in torque is approaching a sine wave. The reason why the static torque characteristic is improved is that the magnetic characteristic buffer member 14 is also magnetized under the influence of the magnetic flux of the magnetic pole projections 3 of the stator 1, and has an effect of gradually changing the self-inductance of the coil 2. is there. Moreover, since the magnetic characteristic buffering member 14 is on the same inner diameter as the magnetic pole protrusion 3, even if the rotor 8 rotates, the self-inductance of the coil 2 changes gradually. Therefore, the function is more reliably performed.

If such a motor is used in which the static torque characteristic of each phase becomes a sine wave, and the current to the coil 2 is also made to flow in a sine wave, the total torque obtained by adding the torque of each phase becomes a constant value.
For example, in the case of 4-phase motor, in the motor phases of torque waveform of a constant unit current becomes a sine wave, when the current supplied to each phase phi ₁ ~ ₄ of the coil to a sine wave, the torque generated Tφ1 by phi ₁ is _Assuming that the phase angle is θ, the torque maximum value is t _M , and the current maximum value is I _M , it is expressed by the following equation (2) using the equation (1).

Tφ ₁ = t _M sin θ × I _M sin θ = t _M I _M sin ² θ (2) [0 ≦ θ ≦ π] Similarly, φ ₂ to φ ₄ are also represented by the following equations (3) to (5). You.

Tφ ₂ = t _M sin (θ + π / 2) × I _M sin (θ + π / 2) = t _M I _M sin ² (θ + π / 2) = t _M I _M cos ² θ (3) [π / 2 ≦ θ _{≦ 3 / 2π] Tφ 3 =} t M I M sin 2 (θ + π) = t M I M sin 2 θ ... (4) [π ≦ θ ≦ 2π] Tφ 4 = t M I M sin 2 (θ + 3 / 2π) ^{_{= t M I M cos 2 θ}} ... (5) [3π / 2 ≦ θ ≦ 5π / 2] Therefore, (2) and (4) from _{Tφ 1 + Tφ 3 = t M} I M sin 2 θ ... ( 6) Further, from the expressions (3) and (5), Tφ ₂ + Tφ ₄ = t _M I _M cin ² θ (7) The total torque Tφ of the motor is given by (6) to (7). Tφ = Tφ _{1 + Tφ 3 + Tφ 2 + Tφ} 4 = t M I M (sin 2 θ + cos 2 θ) = t M I M ... (8) Therefore, the total torque from the equation (8) becomes a constant,
The torque pulsation during driving is eliminated, and the vibration of the motor itself is reduced.

Even if the static torque characteristic does not become a sine wave due to the magnetic characteristic buffer member 14, a relatively simple current waveform that can maintain a constant torque can be provided to the computer if the sharp torque change is eliminated as shown in FIG. The pulsation of the torque can be easily reduced also by the electronic control device which stores the pattern and stores the waveform current.

Further, as another embodiment, instead of forming the magnetic characteristic buffering member entirely of a magnetic material and a semi-magnetic material, a part of the magnetic characteristic buffering member is formed of a material that does not easily transmit magnetic flux, so that leakage between the magnetic pole projections of the stator can be prevented. Magnetic flux can also be prevented.

[Effects of the Invention] As described above, according to the present invention, since the magnetic characteristic buffering member is provided between the magnetic pole projections of the stator, the inductance of the coil during driving gradually changes. . Moreover, the inner peripheral end surface of the magnetic characteristic buffering member and the inner peripheral end surface of the magnetic pole projection of the stator are:
They are formed to have the same inner diameter. Thus, there is no way that the magnetic resistance when the rotor rotates changes drastically with the increase and decrease of the air gap distance unlike the conventional variable reluctance motor. Therefore, the generated static torque characteristic also does not show a rapid change, approaches a sine wave,
Therefore, there is no pulsation in the torque during rotation, and a reluctance motor with less vibration can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a half sectional view showing a variable reluctance motor according to one embodiment of the present invention, FIG. 2 is a perspective view showing the stator of the embodiment in a cutaway manner, and FIG. FIG. 4 is a graph showing static torque characteristics of the motor according to the example, FIG. 4 is an explanatory diagram showing the principle of a variable reluctance motor, and FIG. 5 is a graph showing characteristics of a conventional motor. DESCRIPTION OF SYMBOLS 1 ... Stator, 2 ... Coil, 3 ... Magnetic pole protrusion 6 ... Output shaft, 7 ... Rotor iron core, 9 ... Magnetic pole protrusion 10 ... Iron core forming member, 13a, 13b ... Engagement groove 14 ... Magnetic property buffering members, 15a, 15b ... cut section

Claims (1)

(57) [Claims] A stator having a plurality of magnetic pole projections provided on an inner peripheral portion thereof, a rotor having a plurality of magnetic pole projections provided on an outer peripheral portion thereof, and a magnetic pole projection of the stator. It is arranged astride,
A magnetic characteristic buffer member made of a magnetic material or a semi-magnetic material, and wherein the inner peripheral end surface of the magnetic characteristic buffer member and the inner peripheral end surface of the magnetic pole projection of the stator have the same inner diameter. A variable reluctance motor characterized in that: