US-12627206-B2 - Rotor structure of rotary electric machine

US12627206B2US 12627206 B2US12627206 B2US 12627206B2US-12627206-B2

Abstract

A rotor structure including a rotor, a stator, and magnetic pole parts provided to a rotor core is provided. Each of the magnetic pole parts includes a fixed magnetic-force magnet magnetized in the radial direction, and first variable magnetic-force magnets disposed at both end sides of the fixed magnetic-force magnet in the circumferential direction, respectively. A magnetization sate of each first variable magnetic-force magnet is changeable in the circumferential direction by a given magnetic flux. The first variable magnetic-force magnets are located radially outward of the fixed magnetic-force magnet. A radially outward part of each first variable magnetic-force magnet is held by a respective holding part of the rotor core at a corner part from radially outward. A gap between each holding part and the stator core is wider than a gap between a general outer circumferential surface of the rotor core and the stator core.

Inventors

Naoki ITASAKA

Assignees

MAZDA MOTOR CORPORATION

Dates

Publication Date: 20260512
Application Date: 20240110
Priority Date: 20230131

Claims (9)

1 . A rotor structure of a rotary electric machine, the rotor structure comprising: a rotor having a rotor core; a stator having a stator core, the stator core being disposed radially outward of the rotor core and being separated from the rotor core with spacing therebetween; and a plurality of magnetic pole parts provided to the rotor core and lined up in a circumferential direction of the rotor core, each of the magnetic pole parts including: a fixed magnetic-force magnet embedded in the rotor core and configured to be magnetized in a radial direction of the rotor core; first variable magnetic-force magnets disposed at both sides of the fixed magnetic-force magnet in the circumferential direction, respectively, and embedded in the rotor core, a magnetization state of each first variable magnetic-force magnet being changeable in the circumferential direction by a given magnetic flux, wherein a magnetizing direction of the fixed magnetic-force magnet of one of the magnetic pole parts and a magnetizing direction of the fixed magnetic-force magnet of another magnetic pole part adjacent to the one magnetic pole part are opposite from each other, wherein the first variable magnetic-force magnets are located radially outward of the fixed magnetic-force magnet, and are formed in a rectangular shape of which a long-side direction is oriented in the radial direction, wherein a radially outward part of each first variable magnetic-force magnet is held by a respective holding part of the rotor core at a corner part, and other parts of each first variable magnetic-force magnet are exposed to a stator side at a location radially inward of the respective holding part, and wherein a gap between each holding part and the stator core is wider than a gap between a general outer circumferential surface of the rotor core and the stator core.
2 . The rotor structure of claim 1 , wherein respective parts of an outer circumferential part of the rotor core, that are each adjacent to a respective one of the holding parts and on a fixed magnetic-force magnet side in the circumferential direction, are bulged parts bulging toward the stator core, and wherein a gap between each bulged part and the stator core is wider than the gap between the general outer circumferential surface of the rotor core and the stator core.
3 . The rotor structure of claim 2 , wherein each of the magnetic pole parts has a respective second variable magnetic-force magnet at a position between the fixed magnetic-force magnet and each first variable magnetic-force magnet and on the fixed magnetic-force magnet side of the respective bulged part in the circumferential direction, each second variable magnetic-force magnet being embedded in the rotor core, a magnetization state of each second variable magnetic-force magnet being changeable in the circumferential direction by the given magnetic flux, wherein a position of each second variable magnetic-force magnet in the radial direction is substantially the same as a position of the respective first variable magnetic-force magnet in the radial direction, and wherein in the outer circumferential part of the rotor core, a respective recess dented radially inward of each bulged part is formed at a location radially outward of the respective second variable magnetic-force magnet.
4 . The rotor structure of claim 3 , wherein each holding part is configured to hold a corner part of the respective first variable magnetic-force magnet by covering from radially outward one of two radially outward corner parts of the respective first variable magnetic-force magnet, that is closer to the fixed magnetic-force magnet, and wherein each bulged part is provided to a part of the rotor core that is adjacent to the respective holding part and on the fixed magnetic-force magnet side in the circumferential direction.
5 . The rotor structure of claim 4 , wherein the gap between each bulged part and the stator core is narrower than the gap between each holding part and the stator core.
6 . The rotor structure of claim 3 , wherein each recess is provided adjacent to the respective bulged part and on the fixed magnetic-force magnet side in the circumferential direction, wherein each recess is located at the same position as the respective second variable magnetic-force magnet in the circumferential direction, and wherein a gap between a bottom part of each recess and the stator core is substantially the same as the gap between each holding part and the stator core.
7 . The rotor structure of claim 2 , wherein each holding part is configured to hold a corner part of the respective first variable magnetic-force magnet by covering from radially outward one of two radially outward corner parts of the respective first variable magnetic-force magnet that is closer to the fixed magnetic-force magnet, and wherein each bulged part is provided to a part of the rotor core that is adjacent to the respective holding part and on the fixed magnetic-force magnet side in the circumferential direction.
8 . The rotor structure of claim 7 , wherein the gap between each bulged part and the stator core is narrower than the gap between each holding part and the stator core.
9 . The rotor structure of claim 2 , wherein a respective recess dented radially inward of each bulged part is provided adjacent to each bulged part and on the fixed magnetic-force magnet side in the circumferential direction, wherein each recess is located at the same position as a respective second variable magnetic-force magnet in the circumferential direction, and wherein a gap between a bottom part of each recess and the stator core is substantially the same as a gap between each holding part and the stator core.

Description

TECHNICAL FIELD The art disclosed herein belongs to a technical field related to a rotor structure of a rotary electric machine. BACKGROUND OF THE DISCLOSURE In recent years, as a rotor of a rotary electric machine, one provided with a fixed magnetic-force magnet for which it is difficult to change a magnetization state, and a variable magnetic-force magnet for which its magnetization state is easily changed is proposed. JP2021-027700A discloses a rotor structure provided with a plurality of magnetic pole parts which are lined up in a circumferential direction of a rotor core. Each magnetic pole part includes a first fixed magnetic-force magnet disposed at the center in the circumferential direction, a variable magnetic-force magnet which is disposed on both sides of the first fixed magnetic-force magnet in the circumferential direction and radially outward of the fixed magnetic-force magnet, a magnetization state thereof being changeable, and a second fixed magnetic-force magnet disposed radially inward of the first fixed magnetic-force magnet. The first fixed magnetic-force magnet is disposed magnetically in series with the variable magnetic-force magnet, and the second fixed magnetic-force magnet is disposed magnetically in parallel with the variable magnetic-force magnet. In JP2021-027700A, the radially outward surface of the variable magnetic-force magnet is located radially inward of the general outer circumferential surface of the rotor core, and is exposed to a stator side. In the case of the rotor structure like JP2021-027700A, the first fixed magnetic-force magnet and the second fixed magnetic-force magnet are magnetized so that their radially outward sides become N-poles. When the magnetizing direction of the variable magnetic-force magnet is oriented in a direction from the variable magnetic-force magnet to the first fixed magnetic-force magnet, the magnetic flux which interlinks with a stator is increased (hereinafter, referred to as a “magnetizing state”). On the other hand, when the magnetizing direction of the variable magnetic-force magnet is oriented in a direction from the first fixed magnetic-force magnet to the variable magnetic-force magnet, the magnetic flux which interlinks with the stator is decreased (hereinafter, referred to as a “demagnetizing state”). Here, when electric current does not flow through the coil, a part of the magnetic flux from the first fixed magnetic-force magnet is inputted into a tooth of the stator. In the demagnetizing state, the magnetic flux inputted from the first fixed magnetic-force magnet is transmitted through the stator core and is drawn into the variable magnet from another tooth, thereby forming a short-circuit path. Since the magnetic flux which forms the short-circuit path inside the stator generates a harmonic component, an iron loss of the motor is increased. If the rotor core is dented in the part of the variable magnetic-force magnet until the radially outward surface of the variable magnetic-force magnet is exposed like in JP2021-027700A, it can be expected to suppress the formation of short-circuited magnetic flux. However, there is a concern that when the rotor rotates, the variable magnetic-force magnet may detach due to the centrifugal force. SUMMARY OF THE DISCLOSURE The art disclosed herein is made in view of the situation described above, and one purpose thereof is to suppress a short circuit of a magnetic flux inside a stator in a demagnetizing state, and to suppress detachment of a variable magnetic-force magnet due to a centrifugal force. In order to solve the above-described problem, a first aspect of the art disclosed herein provides a rotor structure of a rotary electric machine. The rotor structure includes a rotor having a rotor core, a stator having a stator core, the stator core being disposed radially outward of the rotor core and being separated from the rotor core with spacing therebetween, and a plurality of magnetic pole parts provided to the rotor core and lined up in a circumferential direction of the rotor core. Each of the magnetic pole parts includes a fixed magnetic-force magnet embedded in the rotor core and configured to be magnetized in a radial direction of the rotor core, first variable magnetic-force magnets disposed at both sides of the fixed magnetic-force magnet in the circumferential direction, respectively, and embedded in the rotor core, a magnetization state of each first variable magnetic-force magnet being changeable in the circumferential direction by a given magnetic flux. A magnetizing direction of the fixed magnetic-force magnet of one of the magnetic pole parts and a magnetizing direction of the fixed magnetic-force magnet of another magnetic pole part adjacent to the one magnetic pole part are opposite from each other. The first variable magnetic-force magnets are located radially outward of the fixed magnetic-force magnet, and are formed in a rectangular shape of which a long-side direction i