JP2012228075A - Electric motor and rotor - Google Patents

Abstract

To provide a rotor of an electric motor that is easy to attach a plurality of permanent magnets to a synthetic resin permanent magnet holding member and does not cause the permanent magnets to be damaged.
In a rotor, a plurality of permanent magnets 21 are held by a synthetic resin permanent magnet holding member 29 fixedly provided on a rotor main body cylindrical portion 28b. The permanent magnet holding member 29 includes an annular portion 32 that is in close contact with both axial end surfaces of the rotor body cylindrical portion 28b, and a connecting portion 33 that is in close contact with the outer peripheral surface of the rotor body cylindrical portion 28a and connects both annular portions 32. Become. The permanent magnet 21 is fitted between two connecting portions 33 adjacent to each other in the circumferential direction, and both the circumferential direction of the permanent magnet 21 from the outside in the radial direction by the engagement holding portions 33a protruding from the respective connecting portions 33 to both sides in the circumferential direction. The edge is suppressed and the permanent magnet 21 is held. A permanent magnet receiving portion 35 interposed between the permanent magnet 21 and the outer peripheral surface of the rotor main body cylindrical portion 28 b is formed integrally with the annular portion 32 and the connecting portion 33 of the permanent magnet holding member 29.
[Selection] Figure 5

Description

  The present invention relates to an electric motor and a rotor in an electric pump unit used as a hydraulic pump for supplying hydraulic pressure to a transmission (transmission) of an automobile, for example.

  Hydraulic pressure is supplied to the vehicle's transmission by a hydraulic pump. However, in order to save energy, the vehicle is stopped when the vehicle is stopped, so-called idle stop (idling stop) is secured. In order to do so, an electric hydraulic pump is used.

  Since the electric hydraulic pump for automobiles is mounted in a limited space of the vehicle body, it is required to be compact, and also required to be light and reduce costs. In order to meet such a demand, an electric pump unit in which a pump, an electric motor for driving a pump, and a controller for the electric motor are incorporated in a common unit housing has been proposed (for example, see Patent Document 1).

  As an electric motor in this type of electric pump unit, a DC brushless motor using a permanent magnet as a rotor is used. A DC brushless motor used for an electric pump unit is generally composed of a motor shaft connected to a pump, a motor rotor fixed to the motor shaft, and a motor stator disposed around the motor rotor. In a conventional DC brushless motor, a ring-shaped permanent magnet or a plurality of segment-shaped permanent magnets are fixed to the outer peripheral surface of a cylindrical rotor body with an adhesive. However, when the permanent magnet is fixed to the rotor body with an adhesive as described above, the adhesive may be peeled off in an electric motor used in a severe environment.

  In order to prevent the permanent magnets from falling off due to the peeling of the adhesive, a plurality of segment-shaped permanent magnets are molded with synthetic resin on the outer peripheral surface of the rotor body, or the synthetic resin is held fixedly on the outer peripheral part of the rotor body It has been proposed to hold a segment-shaped permanent magnet with a permanent magnet holding member such as a container. (For example, refer to Patent Document 2).

JP 2008-215088 A JP 2010-004661 A

  A plurality of permanent magnets held by the synthetic resin permanent magnet holding member on the outer periphery of the rotor body are magnetized. Before the permanent magnet is attached to the permanent magnet holding member, the permanent magnet is magnetized. There are so-called pre-magnetization for magnetizing and so-called post-magnetization for magnetizing the permanent magnet attached to the permanent magnet holding member.

The rotor body is called a back yoke and is made of a magnetic material.
In the case of pre-magnetization, the already magnetized permanent magnet is attracted to the rotor body and comes into close contact with the rotor body.

  In the case of post-magnetization, after attaching all the permanent magnets to the permanent magnet holding member on the outer peripheral portion of the rotor body, a magnetizing device is arranged around the permanent magnets and magnetized. In this case, the permanent magnet is attracted to the magnetizing device with a strong force at the moment of magnetization, and the permanent magnet holding member made of synthetic resin is elastically deformed and moved outward in the radial direction of the rotor body. Get away from. When the magnetization is finished, a permanent magnet having a magnetic force is attracted to the rotor body and collides with the rotor body. At this time, a relatively brittle permanent magnet may be damaged.

  An object of the present invention is to provide an electric motor and a rotor that solve the above-described problems and that allow easy attachment of a plurality of permanent magnets to a synthetic resin permanent magnet holding member and that the permanent magnets are not damaged. .

  A rotor according to the present invention is a rotor of an electric motor in which a plurality of permanent magnets are held on a synthetic resin permanent magnet holding member fixedly provided on a rotor body cylindrical portion. An annular portion that is in close contact with both axial end surfaces of the cylindrical portion, and a connecting portion that is in close contact with the outer peripheral surface of the rotor body cylindrical portion and connects both annular portions at a plurality of locations in the circumferential direction of the rotor body cylindrical portion, A permanent magnet is fitted between two connecting portions adjacent to each other in the circumferential direction, and the circumferential direction of the permanent magnet from the radially outer side of the rotor main body cylindrical portion is an engagement holding portion projecting from each connecting portion to both sides in the circumferential direction. By suppressing both edges, the permanent magnet is held, and the permanent magnet receiving portion interposed between the permanent magnet and the outer peripheral surface of the rotor body cylindrical portion is an annular ring of the permanent magnet holding member. Few parts and connecting parts And also characterized in that it is formed integrally on one.

  The permanent magnet held by the permanent magnet holding member is magnetized by pre-magnetization or post-magnetization.

  In the case of post-magnetization, when the permanent magnet held by the permanent magnet holding member is finished, the permanent magnet having magnetic force is attracted to the rotor body. At this time, since the permanent magnet receiving portion is interposed between the permanent magnet and the rotor main body, the permanent magnet does not collide with the rotor main body, and therefore the permanent magnet is not damaged.

  Since the permanent magnet receiving portion is interposed between the permanent magnet and the rotor body, the permanent magnet can be mounted on the permanent magnet body without being in close contact with the rotor body. For this reason, even in the case of pre-magnetization in which the already magnetized permanent magnet is attached to the permanent magnet holding member, the operation of attaching the permanent magnet is relatively easy.

  For example, the permanent magnet receiving portions are formed at the four corners of a rectangular space surrounded by the two annular portions of the permanent magnet holding member and the two connecting portions adjacent in the circumferential direction.

  For example, the permanent magnet receiving part is formed over the entire circumferential side of each connecting part of the permanent magnet holding member.

  For example, the permanent magnet receiving portion is formed over the entire annular portion between the two connecting portions adjacent to each other in the circumferential direction of the permanent magnet holding member.

  The electric motor according to the present invention includes the rotor according to the present invention.

  According to the electric motor and the rotor of the present invention, as described above, it is easy to attach the plurality of permanent magnets to the synthetic resin permanent magnet holding member, and the permanent magnets are not damaged.

FIG. 1 is a longitudinal sectional view of an electric pump unit showing a first embodiment of the present invention. FIG. 2 is an enlarged arrow view taken along line II-II in FIG. FIG. 3 is an enlarged longitudinal sectional view showing a part of FIG. FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a virtual exploded perspective view of the rotor of the electric motor. FIG. 6 is a perspective view of a permanent magnet holding member showing a second embodiment of the present invention. FIG. 7 is a longitudinal sectional view corresponding to FIG. 3 showing a second embodiment of the present invention. FIG. 8 is a perspective view of a permanent magnet holding member showing a third embodiment of the present invention. FIG. 9 is a longitudinal sectional view corresponding to FIG. 3, showing a third embodiment of the present invention.

  Hereinafter, with reference to the drawings, several embodiments in which the present invention is applied to an electric motor in an electric pump unit used in a hydraulic pump of an automobile will be described.

  1 to 5 show a first embodiment.

  FIG. 1 is a longitudinal sectional view of the electric pump unit. In the following description, the left side of FIG. 1 is the front and the right side is the rear.

  The electric pump unit is a unit housing (1) in which a pump (2) and an electric motor (3) for rotationally driving the pump (2) are integrated. The controller (4) of the motor (3) is also incorporated in the housing (1). In this example, the pump (2) is an internal gear pump, and the motor (3) is a sensorless control DC brushless motor having a three-phase winding.

  The unit housing (1) consists of a pump housing (5), pump plate (6), motor housing (7) and lid (8), and is waterproof by the pump housing (5), motor housing (7) and lid (8). A housing (9) is constructed.

  The pump housing (5) has a thick plate shape that extends in a direction perpendicular to the front-rear direction, and a pump chamber (10) having an open front is formed at the center thereof. A pump plate (6) is fixed to the front surface of the pump housing (5) via an O-ring (11), and the front surface of the pump chamber (10) is closed. An outer gear (12) constituting the pump (2) is rotatably accommodated in the pump chamber (10), and an inner gear (13) that meshes with the inner gear (12) is disposed inside the outer gear (12). Although not shown, the pump plate (6) is provided with an oil suction port and an oil discharge port that communicate with the pump chamber (10).

  The motor housing (7) has a cylindrical shape, and a front end thereof is fixed to a portion near the outer periphery of the rear surface of the pump housing (5) via a seal member (14). The rear end opening of the motor housing (7) is closed by the lid (8).

  A cylindrical portion (5a) having a smaller diameter than the motor housing (7) is integrally formed at the center of the rear end surface of the pump housing (5), and a bearing device (15) provided at the rear portion in the cylindrical portion (5a) A pump drive motor shaft (16) extending in the front-rear direction is cantilevered. In this example, the bearing device (15) includes two ball bearings (17) that are adjacent to the front and rear, and the inner ring (17a) of each bearing (17) is fixed to the motor shaft (16). The outer ring (17b) is fixed to the cylindrical portion (5a). The front part of the motor shaft (16) passes through the hole (18) formed in the rear wall of the pump housing (5) and enters the pump chamber (10), and the front end of the motor shaft (16) reaches the inner gear (13). It is connected. An oil seal (19) is provided between a portion of the cylindrical portion (5a) in front of the bearing device (15) and the motor shaft (16).

  A motor rotor (20) constituting the motor (3) is fixed to a rear end portion of the motor shaft (16) protruding rearward from the cylindrical portion (5a). The rotor (20) has a cylindrical shape extending radially from the rear end of the motor shaft (16) and surrounding the outer periphery of the bearing device (15), and a permanent magnet (21) is fixed to the outer periphery. The axial position of the center of gravity of the rotating portion including the motor shaft (16), the rotor (20), and the inner gear (13) of the pump (2) is within the axial range of the bearing device (15). In this example, the axial position of the center of gravity is between the two ball bearings (17) constituting the bearing device (15).

  A motor stator (22) constituting the motor (3) is fixedly provided on the inner periphery of the motor housing (7) facing the rotor (20). The stator (22) is an insulator (synthetic resin insulator) (24) incorporated in a core (23) made of laminated steel plates, and a stator coil (25) is wound around the insulator (24). . In this example, the stator (22) is fixed to the inner periphery of the motor housing (7) by an appropriate means such as adhesion on the outer periphery of the core (23).

  The board (26) of the controller (4) is fixed to the rear end of the insulator (24), and a component (27) constituting the controller (4) is attached to the board (26). The component is disposed at a predetermined position on at least one of the front surface and the rear surface of the substrate (26). In the drawing, one component (27) attached to the rear surface of the substrate (26) is shown.

  2 to 5 show details of the rotor (20). 2 is an enlarged arrow view taken along line II-II in FIG. 1, FIG. 3 is a longitudinal sectional view showing a part of the rotor 20 of FIG. 1 enlarged, and FIG. 4 is taken along line IV-IV in FIG. FIG. 5 is a virtual exploded perspective view of the rotor (20).

  In the rotor (20), a permanent magnet holding member (29) made of synthetic resin is fixedly provided on the outer periphery of a cylindrical rotor body (back yoke) (28), and the holding member (29) is equally divided in the circumferential direction. The segment-shaped permanent magnet (21) is held at a plurality of locations (eight locations in this example).

  The rotor body (28) is formed by sintering, for example, and is integrally formed on the flange portion (28a) fixed to the motor shaft (16) and the outer peripheral edge of the flange portion (28a). A cylindrical portion (28b) extending forward from the inside of the stator (22) so as to surround the outer periphery of (15). A small diameter portion (16a) formed at the rear end of the motor shaft (16) is fixed by press fitting into a circular through hole (30) formed at the center of the flange portion (28a). The entire outer peripheral surface of the cylindrical portion (28b) is a cylindrical surface, and the cross-sectional shape of the outer peripheral surface is circular.

  In the outer peripheral portion of both ends of the cylindrical portion (28b), the rotation preventing concave portions (31) are formed at a plurality of locations (eight locations in this example) equally divided in the circumferential direction. In this example, the concave portion (31) is formed in the outermost peripheral portion of both end faces of the cylindrical portion (28b), and has a notch shape extending from the outer peripheral portion of the cylindrical portion (28b) to the end portion of the outer peripheral surface.

  The holding member (29) is integrated with the cylindrical portion (28b) by molding a synthetic resin into the cylindrical portion (28b) using a mold. The holding member (29) includes an annular portion (32) that is in close contact with both end faces of the cylindrical portion (28b), and an annular portion (32) that is in close contact with the outer peripheral surface of the cylindrical portion (28b) at a plurality of locations in the circumferential direction. It consists of a plurality of rod-like connecting portions (33) that are connected and hold the permanent magnet (21). A plurality of anti-rotation convex portions (34) that fit into the concave portions (31) of the cylindrical portion (28b) are integrally formed on the mutually opposing surfaces of both annular portions (32). Each coupling portion (33) is integrally formed with two engagement holding portions (33a) projecting from the radially outer end to both sides in the circumferential direction.

  At the four corners of the rectangular space surrounded by the two annular portions (32) and the two connecting portions (33) adjacent in the circumferential direction, the rectangular permanent magnet receiving portion (35) is an annular portion ( 32) and the connecting portion (33). The permanent magnet receiving part (35) is in close contact with the outer peripheral surface of the cylindrical part (28b).

  The permanent magnet (21) is between two connecting portions (33) adjacent in the circumferential direction, and between the engagement holding portion (33a) of the connecting portion (33) and the permanent magnet receiving portion (35). Inserted from the axial direction, the circumferential edges of the permanent magnet (21) are held by being sandwiched between the engagement holding portion (33a) and the permanent magnet receiving portion (35). In this state where the permanent magnet (21) is held by the holding member (29), the permanent magnet receiving portion (35) is interposed between the permanent magnet (21) and the outer peripheral surface of the cylindrical portion (28b), The permanent magnet (21) does not contact the outer peripheral surface of the cylindrical portion (28b).

  At least one key groove (36) is formed in the through hole (30) of the flange portion (28a) of the rotor body (28). In this example, two key grooves (36) are formed at two symmetrical positions of the hole (30).

  Since the holding member (29) is formed integrally with the rotor body (28), the two are not separated, but in order to facilitate understanding of the configuration of both, in FIG. It is shown as a separate exploded perspective view.

  In the electric pump unit, for example, the permanent magnet (21) held by the holding member (29) as described above is magnetized by post-magnetization.

  In this case, when the permanent magnet (21) held by the holding member (29) has been magnetized, the permanent magnet (21) having a magnetic force is attracted to the rotor body (28). At this time, since the permanent magnet receiving portion (35) is interposed between the permanent magnet (21) and the rotor body (28), the permanent magnet (21) does not collide with the rotor body (28). There is no risk of the permanent magnet (21) being damaged.

  The anti-rotation recess formed in the cylindrical portion (28b) of the rotor body (28) is not a notched recess (31) extending from the end surface of the cylindrical portion (28b) to the outer peripheral surface as described above, but the cylindrical portion (28b ) May be a bottomed hole formed at one of a plurality of locations on the end surface and the outer peripheral surface, or at a plurality of locations of both. In that case, the non-rotating convex portion of the holding member (29) is provided at a position corresponding to the concave portion which is a bottomed hole. When the rotor body is a sintered body, it is difficult to process the hole, so the notch-shaped recess (31) as described above is preferable.

  In the motor (3) and the rotor (20), when the permanent magnet holding member (29) is integrally formed with the cylindrical portion (28b) of the rotor body (28), the key groove (36) of the hole (30) is formed. Can be used for phasing, and the mold and molding process can be simplified. Also, since the key groove (36) is only provided in the through hole (30) formed in the rotor body (28), the structure of the mold when the rotor body (28) is made of a sintered body is simplified. The

  In addition, since the non-rotating convex portion (34) of the permanent magnet holding member (29) is fitted in the non-rotating concave portion (31) of the rotor body (28), the entire outer peripheral surface of the rotor main body (28) is a cylindrical surface. Even if the cross-sectional shape of the outer peripheral surface is circular, the permanent magnet holding member (29) does not slip in the circumferential direction with respect to the rotor body (28) by rotation, and the permanent magnet holding member (29) is fixed. Is certain. And since the outer peripheral surface of a rotor main body (28) is a cylindrical surface, the process is easy and can be manufactured cheaply.

  In the electric pump unit, one axial position of the motor shaft (16) is cantilevered by the bearing device (15), and the motor rotor (20) is provided so as to surround the outer periphery of the bearing device (15). Because of the structure, the length of the motor shaft (16) can be shortened, and further downsizing is possible. Further, since the axial position of the center of gravity of the rotating part including the motor shaft (16), the motor rotor (20) and the inner gear (13) of the pump (2) is within the axial range of the bearing device (15), the rotating part Can be stably rotated. Furthermore, since the position of the center of gravity in the axial direction is between the two ball bearings (17) constituting the bearing device (15), the rotating part can be supported in a more stable manner. Further, the bearing device (15) can be supported only by the cylindrical portion (5a) formed integrally with the pump housing (5), and no other member for supporting the bearing device (15) is required. For this reason, the number of parts can be further reduced, and further weight reduction and cost reduction are possible.

  6 and 7 show a second embodiment. 6 is a perspective view of the permanent magnet holding member (29), and FIG. 7 is a longitudinal sectional view corresponding to FIG. 3 of the first embodiment.

  The configuration of the electric pump unit of the second embodiment is the same as that of the first embodiment except for the configuration of the permanent magnet holding member (29) described later.

  In the case of the second embodiment, the permanent magnet receiving portion (37) of the holding member (29) is formed over the entire circumferential side of each connecting portion (33), and the connecting portion (33) and the annular portion (32). It is united with.

  Also in the second embodiment, similarly to the first embodiment, the permanent magnet receiving portion (37) prevents the permanent magnet (21) from being damaged during the post-magnetization. In particular, in the case of the second embodiment, the circumferential edges of the permanent magnet (21) can be received by the permanent magnet receiving portion (37) extending over the entire length of the connecting portion (33), so that the already magnetized permanent magnet (21 ) Can be inserted along the permanent magnet receiving portion (37) without bringing the permanent magnet (21) into close contact with the rotor body (28), even in the case of pre-magnetization to attach the holding member (29). The attachment work of the magnet (21) is relatively easy.

  Others are the same as those in the first embodiment.

  8 and 9 show a third embodiment. FIG. 8 is a perspective view of the permanent magnet holding member (29), and FIG. 9 is a longitudinal sectional view corresponding to FIG. 3 of the first embodiment.

  The configuration of the electric pump unit of the third embodiment is the same as that of the first embodiment except for the configuration of a permanent magnet holding member (29) described later.

  In the case of the third embodiment, the permanent magnet receiving portion (38) of the holding member (29) is formed over the entire annular portion (32) between two connecting portions (33) adjacent in the circumferential direction. It is integrated with the part (32) and the connecting part (33).

  Also in the second embodiment, as in the first embodiment, the permanent magnet receiving portion (38) prevents the permanent magnet (21) from being damaged during post-magnetization.

  Others are the same as those in the first embodiment.

  The overall configuration of the electric pump unit and the configuration of each unit are not limited to those of the above-described embodiment, and can be changed as appropriate.

  Moreover, this invention is applicable also to electric motors other than the electric pump unit for motor vehicles.

(3) Electric motor
(20) Motor rotor
(21) Permanent magnet
(28) Rotor body
(28a) Rotor body cylindrical part
(29) Permanent magnet holding member
(32) Annulus
(33) Connecting part
(33a) Engagement holding part
(35) (37) (38) Permanent magnet holder

Claims (5)

In the rotor of the electric motor in which a plurality of permanent magnets are held on a synthetic resin permanent magnet holding member fixedly provided on the rotor body cylindrical portion,
The permanent magnet holding member is in close contact with both axial end surfaces of the rotor main body cylindrical portion, and is connected to the outer peripheral surface of the rotor main body cylindrical portion, and the two circular portions are connected at a plurality of locations in the circumferential direction of the rotor main body cylindrical portion. The permanent magnet is fitted between two connecting portions adjacent to each other in the circumferential direction, and the radial direction of the rotor main body cylindrical portion is an engagement holding portion projecting from each connecting portion to both sides in the circumferential direction. By suppressing the circumferential edges of the permanent magnet from the outside, the permanent magnet is held,
A rotor, wherein a permanent magnet receiving portion interposed between the permanent magnet and the outer peripheral surface of the rotor main body cylindrical portion is formed integrally with at least one of the annular portion and the connecting portion of the permanent magnet holding member.   The permanent magnet receiving portion is formed at four corners of a rectangular space surrounded by two annular portions of the permanent magnet holding member and two connecting portions adjacent in the circumferential direction. Item 1. The rotor according to item 1.   The rotor according to claim 1, wherein the permanent magnet receiving portion is formed over the entire sides in the circumferential direction of the connecting portions of the permanent magnet holding member.   The rotor according to claim 1, wherein the permanent magnet receiving portion is formed over the entire annular portion between the two connecting portions adjacent to each other in the circumferential direction of the permanent magnet holding member.   An electric motor comprising the rotor according to claim 1.

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