JP7548026B2 - Rotating Electric Machine - Google Patents

Description

This invention relates to rotating electric machines, and more specifically to variable flux type rotating electric machines.

Patent Document 1 discloses an electric motor that includes a rotor having a permanent magnet and that can change the field characteristics of the permanent magnet. This electric motor includes first and second rotors that are divided and arranged concentrically. In order to switch between the presence and absence of leakage of magnetic flux from the permanent magnet to the magnetic flux short-circuit plate, this electric motor includes a moving means for moving the second rotor circumferentially and axially relative to the first rotor.

JP 2007-267453 A

In the electric motor described in Patent Document 1, a separate actuator (moving means) is required to move the second rotor relative to the first rotor in order to switch between the presence and absence of leakage of magnetic flux from the permanent magnet to the magnetic flux short-circuit plate.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a rotating electric machine equipped with a magnetic flux variable mechanism that can switch between allowing and not allowing magnetic flux leakage from the rotor's permanent magnets without the need for a separate actuator.

A rotating electric machine according to the present invention includes a rotor, a stator, and a magnetic flux variable mechanism. The rotor has a permanent magnet. The stator is disposed facing the rotor in the radial direction of the rotor and has a stator coil. The magnetic flux variable mechanism is disposed at least at one end of the rotor in the axial direction of the rotor, and is configured to have a first operating state and a second operating state that change according to a current supply condition of the stator, thereby being capable of switching between the presence and absence of magnetic flux leakage from the permanent magnet.
The magnetic flux variable mechanism includes a magnetic flux short-circuiting member that rotates in synchronization with the rotor and is arranged so as to be freely movable in the axial direction, a first spring that urges the magnetic flux short-circuiting member away from the rotor in the axial direction, a ring that rotates in synchronization with the rotor and is arranged so as to be freely rotatable relative to the rotor and has a first stopper portion that is interposed between the magnetic flux short-circuiting member and the rotor in a second operating state, a second spring that urges the ring in the circumferential direction of the rotor, and a housing that rotates in synchronization with the rotor and has a second stopper portion that is located farther from the rotor in the axial direction than the magnetic flux short-circuiting member.
In a first operating state in which the axial electromagnetic force generated in the rotor as a result of current being passed through the stator coil is equal to or greater than the elastic force of the first spring and the circumferential electromagnetic force generated in the rotor as a result of current being passed through the stator coil is less than the elastic force of the second spring, the ring is in a circumferential position in which the first stopper portion is not interposed between the flux short-circuiting member and the rotor, and the flux short-circuiting member abuts against the rotor.
In a second operating state in which the electromagnetic force in the axial direction is less than the elastic force of the first spring and the electromagnetic force in the circumferential direction is greater than or equal to the elastic force of the second spring, the flux short-circuiting member is separated from the rotor in the axial direction and abuts against the second stopper portion, and the ring is in a circumferential position where the first stopper portion is interposed between the flux short-circuiting member and the rotor.

According to the present invention, by providing a magnetic flux variable mechanism having the above-mentioned configuration, it is possible to switch between the presence and absence of magnetic flux leakage from the permanent magnet by changing the current flow conditions of the stator and by utilizing the elastic forces of the first and second springs. Therefore, it is possible to switch between the presence and absence of magnetic flux leakage from the permanent magnet without the need for a separate actuator.

3 is a schematic diagram showing a configuration of a rotating electric machine as viewed in the axial direction of a rotation shaft of a rotor at the position of a magnetic flux short-circuit member (first operating state). FIG. 2A is a cross-sectional view taken along line AA of the rotating electric machine shown in FIG. 1 , and FIG. 2B is a cross-sectional view taken along line BB of the rotating electric machine shown in FIG. 11 is a schematic diagram showing the configuration of a rotating electric machine as viewed in the axial direction of a rotation shaft of a rotor at the position of a magnetic flux short-circuit member (second operating state). FIG. 4A is a cross-sectional view taken along line CC of the rotating electric machine shown in FIG. 3, and FIG. 4B is a cross-sectional view taken along line DD of the rotating electric machine shown in FIG.

Below, the embodiments of the present invention will be described with reference to the attached drawings. However, when the numbers, quantities, amounts, ranges, etc. of each element are mentioned in the embodiments shown below, the invention is not limited to the mentioned numbers unless otherwise specified or clearly specified in principle. Furthermore, the structures etc. described in the embodiments shown below are not necessarily essential to the invention, unless otherwise specified or clearly specified in principle.

1. Configuration of the rotating electric machine Fig. 1 is a schematic diagram showing the configuration of a rotating electric machine 1 as viewed from the axial direction of a rotating shaft 12 of a rotor 10 at the position of a flux short-circuit member 32. Fig. 2(A) is a cross-sectional view taken along line A-A of the rotating electric machine 1 shown in Fig. 1, and Fig. 2(B) is a cross-sectional view taken along line B-B of the rotating electric machine 1 shown in the same figure. The rotating electric machine 1 includes a rotor 10, a stator 20, and a magnetic flux variable mechanism 30.

The rotor 10 includes a rotating shaft 12 and a rotor core 14 that rotates integrally with the rotating shaft 12. The rotor 10 has a plurality of permanent magnets 16 embedded inside the rotor core 14, and constitutes the field of the rotating electric machine 1. The rotor core 14 is formed, for example, by stacking a plurality of electromagnetic steel sheets.

The stator 20 includes a stator core 22 and a stator coil 24 wound around the stator core 22. The stator 20 constitutes the armature of the rotating electric machine 1. The stator 20 is arranged to face the rotor 10 in the radial direction D2 of the rotor 10. More specifically, as an example, the stator 20 is arranged radially outward from the rotor 10. The current flow through the stator 20 (stator coil 24) is controlled by an inverter (not shown).

The magnetic flux variable mechanism 30 is configured to be able to switch between leakage and non-leakage of magnetic flux (magnetic flux) from the permanent magnets 16 in order to change the magnetomotive force of the rotor 10 and achieve both high torque and high rotation of the rotating electric machine 1. In the example shown in Figures 1 and 2, the magnetic flux variable mechanism 30 is disposed at one end of the rotor 10 in the axial direction D1 of the rotor 10. However, instead of the example shown in Figure 1, the magnetic flux variable mechanism 30 may be disposed at both ends of the rotor 10 in the axial direction D1.

Specifically, the magnetic flux variable mechanism 30 has a "first operating state" and a "second operating state" that change depending on the current flow conditions of the stator 20, and is therefore capable of switching between the presence and absence of leakage of magnetic flux. The first and second operating states of the magnetic flux variable mechanism 30 will be described in detail later.

The magnetic flux variable mechanism 30 includes a magnetic flux short-circuiting member 32, a first spring 34, a ring 36, a second spring 38, and a housing 40.

The magnetic flux short-circuiting member 32 is supported, for example, by the rotating shaft 12 so that it rotates in synchronization with the rotor 10 (rotor core 14) and is movable in the axial direction D1. More specifically, the magnetic flux short-circuiting member 32 is an annular magnetic flux short-circuiting plate that faces the rotor core 14 and is made of a magnetic material such as an electromagnetic steel plate.

The first springs 34 have an elastic force that urges the magnetic flux short-circuiting members 32 away from the rotor 10 in the axial direction D1. For example, any number of first springs 34 are attached to the end surface 14a of the rotor core 14 that faces the magnetic flux short-circuiting members 32.

The ring 36 is supported, for example, by a housing 40 so that it rotates in synchronization with the rotor 10 (rotor core 14) and can rotate relatively to the rotor 10 (rotor core 14). The ring 36 is composed of a stopper portion 36a (corresponding to an example of a "first stopper portion" according to the present invention) and a cylindrical portion 36b. The cylindrical portion 36b is located at the same radial position as the outer peripheral surface of the rotor core 14. The number of stopper portions 36a is not particularly limited, but in the example shown in FIG. 1, four stopper portions 36a are arranged at equal angular intervals in the circumferential direction D3 of the rotor 10.

The stopper portion 36a is formed as a protrusion extending inward in the radial direction D2 from the inner peripheral surface of the cylindrical portion 36b. The stopper portion 36a is interposed between the magnetic flux shunt member 32 and the rotor 10 (rotor core 14) in the first operating state (see Figures 3 and 4 described below). The ring 36 is formed, for example, from a non-magnetic material.

The second spring 38 has an elastic force that biases the ring 36 (stopper portion 36a) in the circumferential direction D3. More specifically, the second spring 38 biases the stopper portion 36a in the rotational direction of the ring 36 when switching from the second operating state to the first operating state described below. The second springs 38 are attached to the end face 14a of the rotor core 14, for example, in any number.

The housing 40 has a stopper portion 40a located farther from the rotor 10 in the axial direction D1 than the magnetic flux short-circuiting member 32, and is supported by, for example, the rotating shaft 12 so as to rotate in synchronization with the rotor 10. The stopper portion 40a corresponds to an example of a "second stopper portion" according to the present invention. Unlike the magnetic flux short-circuiting member 32, the position of the housing 40 in the axial direction D1 is fixed (it does not move). Also, unlike the ring 36, the housing 40 is configured not to rotate relative to the rotor 10.

The above-mentioned Figures 1 and 2 show the magnetic flux variable mechanism 30 in the first operating state. More specifically, Figure 2(A) shows a cross section at a circumferential position where the stopper portion 36a is not present, and Figure 2(B) shows a cross section at a circumferential position where the stopper portion 36a is present.

The first operating state corresponds to an operating state in which the electromagnetic force F1 in the axial direction D1 generated in the rotor 10 in response to the energization of the stator coil 24 is equal to or greater than the elastic force of the first spring 34, and the electromagnetic force F2 in the circumferential direction D3 generated in the rotor 10 in response to the energization of the stator coil 24 is less than the elastic force of the second spring 38. In this first operating state, the ring 36 is in a circumferential position where the stopper portion 36a is not interposed between the magnetic flux short-circuiting member 32 and the rotor 10. The magnetic flux short-circuiting member 32 is in contact with the rotor 10 (rotor core 14).

As described above, in the first operating state, the magnetic flux short-circuiting member 32 is held on the rotor 10 side. As a result, the magnetic flux of the permanent magnet 16 is short-circuited by the magnetic flux short-circuiting member 32. This causes magnetic flux leakage from the permanent magnet 16 to the magnetic flux short-circuiting member 32. The first operating state is selected, for example, when the rotating electric machine 1 is made to function as a motor and rotates at high speed. By selecting the first operating state, magnetic flux leakage occurs and the back electromotive voltage is suppressed, so that the rotor 10 can be rotated at high speed. Therefore, the output of the rotating electric machine 1 can be improved.

Next, FIG. 3 is a schematic diagram showing the configuration of the rotating electric machine 1 as viewed from the axial direction of the rotating shaft 12 of the rotor 10 at the position of the magnetic flux short-circuiting member 32. FIG. 4(A) is a cross-sectional view of the rotating electric machine 1 shown in FIG. 3 taken along line C-C, and FIG. 4(B) is a cross-sectional view of the rotating electric machine 1 shown in the same figure taken along line D-D. FIGS. 3 and 4 show the magnetic flux variable mechanism 30 in the second operating state. More specifically, FIG. 4(A) shows a cross-section at a circumferential position where the stopper portion 36a is not present, and FIG. 4(B) shows a cross-section at a circumferential position where the stopper portion 36a is present.

The second operating state corresponds to an operating state in which the electromagnetic force F2 in the axial direction D1 is less than the elastic force of the first spring 34, and the electromagnetic force F2 in the circumferential direction D3 is greater than or equal to the elastic force of the second spring 38. In this second operating state, the magnetic flux short-circuiting member 32 is separated from the rotor 10 in the axial direction D1 and abuts against the stopper portion 40a of the housing 40. The ring 36 is in a circumferential position in which the stopper portion 36a is interposed between the magnetic flux short-circuiting member 32 and the rotor 10. That is, in the second operating state, the magnetic flux short-circuiting member 32 is held in an axial position separated from the rotor 10. Therefore, even if an external force acts on the magnetic flux short-circuiting member 32 due to a disturbance, the stopper portion 36a is interposed, so that the magnetic flux short-circuiting member 32 is prevented from moving toward the rotor 10.

As described above, in the second operating state, the flux short-circuiting member 32 is held at an axial position away from the rotor 10. As a result, the magnetic flux of the permanent magnet 16 is not short-circuited by the flux short-circuiting member 32. Therefore, no magnetic flux leakage occurs from the permanent magnet 16 to the flux short-circuiting member 32. The second operating state is selected, for example, when the rotating electric machine 1 is made to function as a motor to obtain high torque. By selecting the second operating state, the rotating electric machine 1 can be operated without leakage of magnet magnetic flux, thereby obtaining high torque.

In addition, the magnetic flux short-circuiting member 32 is basically formed in a circular ring shape as described above. However, the magnetic flux short-circuiting member 32 is formed so that in the second operating state, it interferes with the stopper portion 36a to restrict movement toward the rotor 10, and in the first operating state, it can move toward the rotor 10 without interfering with the stopper portion 36a (in other words, it has a cutout portion that realizes such a function).

2. Effects As described above, according to the rotating electric machine 1 including the magnetic flux variable mechanism 30, the operating state of the magnetic flux short-circuiting member 32 can be switched between the first operating state and the second operating state, thereby switching the presence or absence of magnetic flux leakage from the permanent magnet 16 of the rotor 10 to the magnetic flux short-circuiting member 32. According to the magnetic flux variable mechanism 30 of the present embodiment, the presence or absence of magnetic flux leakage can be switched by changing the current supply condition of the stator 20 and by utilizing the elastic forces of the first and second springs 34, 38. Therefore, it is possible to switch the presence or absence of magnetic flux leakage without the need to provide an actuator separately. In addition, it is possible to suppress the increase in size and cost of the rotating electric machine 1 caused by the addition of such an actuator.

REFERENCE SIGNS LIST 1 Rotary electric machine 10 Rotor 12 Rotor shaft 14 Rotor core 14a End surface of rotor core 16 Permanent magnet of rotor 20 Stator 22 Stator core 24 Stator coil 30 Magnetic flux variable mechanism 32 Magnetic flux short-circuit member 34 First spring 36 Ring 36a Stopper portion of ring (first stopper portion)
36b: Cylindrical portion of ring 38: Second spring 40: Housing 40a: Stopper portion of housing (second stopper portion)

Claims (1)

A rotor having a permanent magnet;
a stator disposed radially opposite the rotor and having a stator coil;
a magnetic flux variable mechanism that is disposed at least on one end of the rotor in the axial direction of the rotor, and has a first operating state and a second operating state that change in response to a current supply condition of the stator, thereby enabling switching between the presence and absence of magnetic flux leakage from the permanent magnet;
A rotating electric machine comprising:
The magnetic flux variable mechanism includes:
a magnetic flux short-circuiting member that rotates in synchronization with the rotor and is arranged so as to be movable in the axial direction;
a first spring that biases the magnetic flux short-circuiting member away from the rotor in the axial direction;
a ring arranged to rotate synchronously with the rotor and to be rotatable relative to the rotor, and having a first stopper portion interposed between the magnetic flux short-circuiting member and the rotor in the second operating state;
a second spring that biases the ring in a circumferential direction of the rotor;
a housing having a second stopper portion located farther away from the rotor than the magnetic flux short-circuiting member in the axial direction, the housing rotating in synchronization with the rotor;
Including,
in a first operating state in which the axial electromagnetic force generated in the rotor in response to energization of the stator coil is equal to or greater than the elastic force of the first spring and the circumferential electromagnetic force generated in the rotor in response to energization of the stator coil is less than the elastic force of the second spring, the ring is in a circumferential position in which the first stopper portion is not interposed between the magnetic flux short-circuiting member and the rotor, and the magnetic flux short-circuiting member is in contact with the rotor,
a rotating electric machine characterized in that in a second operating state in which the electromagnetic force in the axial direction is less than the elastic force of the first spring and the electromagnetic force in the circumferential direction is equal to or greater than the elastic force of the second spring, the magnetic flux short-circuiting member is spaced from the rotor in the axial direction and abuts against the second stopper portion, and the ring is in a circumferential position where the first stopper portion is interposed between the magnetic flux short-circuiting member and the rotor.

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