Patent ID: 12191733

DETAILED DESCRIPTION

Hereinafter, example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that a direction in which the center axis C of the motor1illustrated inFIG.1extends is simply referred to as an “axial direction”, and a radial direction and a circumferential direction around the center axis C of the motor1are simply referred to as a “radial direction” and a “circumferential direction”. Note that the “axial direction”, the “radial direction”, and the “circumferential direction” are names used merely for description, and do not limit the actual positional relationship or direction. In the present example embodiment, for convenience of description, the axial direction is defined as the vertical direction, and the vertical direction inFIG.3is defined as the vertical direction of the motor, and the shape and positional relationship of each part will be described. However, there is no intention to limit the direction at the time of manufacture and use of a motor1according to the disclosure by this definition of the vertical direction.

A motor according to an example embodiment of the present disclosure will be described.FIGS.1and2are a perspective view and an exploded perspective view of a motor1according to an example embodiment of the present disclosure.FIG.3is a longitudinal cross-sectional view of the motor1, andFIG.4is an enlarged longitudinal cross-sectional view of part of the motor1.FIG.5is an exploded perspective view of a housing50.

In the motor1, the motor body100and the control unit200are accommodated and integrated in the housing50. The motor body100includes a rotor20, a stator30, an upper bearing (bearing)41, a lower bearing42, a bearing holder52, and a bus bar assembly60.

The control unit200is located axially above the motor body100and controls the rotation of the rotor20. The control unit200includes a first circuit board80, a second circuit board (circuit board)83, and a connector unit82. The connector unit82is electrically connected to the first circuit board80, and supplies a drive current from an external power source to the first circuit board80and the second circuit board83.

The motor body100and the control unit200are electrically connected by connection between a circuit terminal84connected to the second circuit board (circuit board)83and the bus bar assembly60. The connection structure between the circuit terminal84and the bus bar assembly60will be described in detail later.

The housing50accommodates the motor body100and the control unit200, and includes a motor housing51, a bearing holder52, and a cover53.

That is, the motor1includes the rotor20, the stator30, the upper bearing (bearing)41, the motor housing51, the bearing holder52, the bus bar assembly60, and the second circuit board (circuit board)83.

The motor housing51is formed in a bottomed cylindrical shape, and accommodates the rotor20and the stator30therein. The motor housing51includes a side wall portion511and a bottom wall portion512. The side wall portion511extends axially upward and is formed in a cylindrical shape. The upper surface of the side wall portion511is opened to form an opening51a. The lower surface of the side wall portion511is covered with a plate-shaped bottom wall portion512. The bottom wall portion512includes a lower bearing holding portion512a. The lower bearing holding portion512ais located on a center axis C, and has an upper surface recessed in the axial direction. The lower bearing42is accommodated and held in the lower bearing holding portion512a. A bottom wall through hole512bpenetrating in the axial direction is formed in the bottom face of the lower bearing holding portion512a.

The bearing holder52holds the upper bearing (bearing)41and covers the opening of the motor housing51. The bearing holder52is located axially above the motor housing51and is formed in a bottomed cylindrical shape. The bearing holder52accommodates the bus bar assembly60and an upper bearing41therein. The bearing holder52includes an intermediate wall portion521, a peripheral wall portion522, an upper cylindrical portion523a, a lower cylindrical portion523b, a recess524, a bearing holder through hole525, an annular coupling portion526, and a holder flange portion527.

The intermediate wall portion521is formed in a plate shape and covers the opening51aof the motor housing51. The intermediate wall portion521has a holder protrusion521a. That is, the bearing holder52has the holder protrusion521a. The holder protrusion521aprotrudes radially outward of the motor housing51. The holder protrusion521ahas an axially penetrating terminal through hole521b. A bus bar cover528that covers the terminal through hole521bis attached to the lower surface of the holder protrusion521a.

The peripheral wall portion522extends axially upward from the peripheral edge of the intermediate wall portion521and is formed in a tubular shape. The upper surface of the peripheral wall portion522is opened to form a bearing holder opening52a.

The upper cylindrical portion523asurrounds the center axis C, extends axially upward from the upper surface of the intermediate wall portion521, and is formed in a cylindrical shape. A magnet holding portion90and a sensor magnet91described later are located in the upper cylindrical portion523a.

The lower cylindrical portion523bsurrounds the center axis C and extends axially downward from the lower surface of the intermediate wall portion521to be formed in a cylindrical shape. The lower cylindrical portion523baccommodates and holds the upper bearing41. The upper cylindrical portion523aand the lower cylindrical portion523bcommunicate with each other in the axial direction.

The recess524is located radially outside of the upper cylindrical portion523aand the lower cylindrical portion523b, and is recessed axially downward from the upper surface of the intermediate wall portion521. The recess524is formed in an annular shape surrounding the upper cylindrical portion523aand the lower cylindrical portion523bin top view. The bearing holder through hole525penetrates the bottom face of the recess524in the axial direction. A plurality of the bearing holder through holes525is located in the circumferential direction. In the present example embodiment, 12 bearing holder through holes525are provided.

The annular coupling portion526protrudes axially downward from the lower surface of the intermediate wall portion521and is formed in an annular shape surrounding the recess524. The annular coupling portion526is press-fitted into the inner face of the side wall portion511of the motor housing51with an O-ring540interposed on the outer peripheral surface thereof. As a result, the annular coupling portion526is fitted into the opening of the motor housing51, and the bearing holder52and the motor housing51are fixed.

The holder flange portion527protrudes radially outward from the upper end portion of the peripheral wall portion522. The four holder flange portions527are provided on the outer peripheral portion of the peripheral wall portion522. The holder flange portion527has a holder screw hole527aextending in the axial direction.

The cover53is formed in a plate shape and covers the bearing holder opening52a. The cover53has a cover flange portion531. The cover flange portion531protrudes radially outward from the outer peripheral portion of the cover53. The four cover flange portions531are provided on the outer peripheral portion of the cover53. The cover flange portion531has an axially penetrating cover hole531a. By aligning and screwing the cover hole531aand the holder screw hole527a, the cover53and the bearing holder52are fixed.

The rotor20includes a shaft21, a rotor core22, and a rotor magnet23. The shaft21forms a rotation axis extending along the center axis C and is formed in a columnar shape. That is, the rotor20has the shaft21extending along the rotation axis. The shaft21is rotatably supported by the upper bearing41and the lower bearing42about the axis.

The lower end portion of the shaft21protrudes outside of the motor housing51through the bottom wall through hole512b. The upper end portion of the shaft21is located inside the upper cylindrical portion523a.

The rotor core22is formed in a cylindrical shape, and the shaft21is fixed inside by press fitting. The rotor magnet23is provided on the radially outer surface of the rotor core22, and a plurality of rotor magnets is located in the circumferential direction. The rotor core22and the rotor magnet23rotate integrally with the shaft21.

The stator30is located radially outside of the rotor20. That is, the stator30faces the rotor20in the radial direction. The stator30is formed in a tubular shape, and the rotor20is located inside the stator30. The stator30includes a core back portion31, a tooth portion32, a coil portion33, and an insulator34.

The core back portion31has a cylindrical shape concentric with the shaft21. The outer peripheral surface of the core back portion31, that is, the outer peripheral surface of the stator30, is fitted to the inner peripheral surface of the side wall portion511of the motor housing51.

The tooth portion32extends radially inward from the inner peripheral surface of the core back portion31. A plurality of the tooth portions32is provided and located at equal intervals in the circumferential direction of the inner peripheral surface of the core back portion31. In the present example embodiment, 12 tooth portions32are provided.

The coil portion33is configured by winding a conductive wire33aaround the insulator34. The insulator34is attached to each tooth portion32. The end portion of the conductive wire33awound around each of the tooth portions32extends axially upward, penetrates each of the bearing holder through holes525, and is connected to the second circuit board83via the bus bar assembly60located inside the bearing holder52.

When a drive current is supplied to the coil portion33, a magnetic field is generated, and the rotor20rotates by the magnetic field.

The sensor magnet91is an annular permanent magnet, and the N pole and the S pole are located on a surface facing the sensor81. The sensor magnet91is fitted to the inner peripheral surface of the tubular magnet holding portion90, and the magnet holding portion90is fitted to the upper end portion of the shaft21.

In the present example embodiment, the sensor magnet91is fixed inside the magnet holding portion90. As a result, the sensor magnet91is connected to the shaft21via the magnet holding portion90and is rotatably located together with the shaft21. The magnet91may be directly fixed to the tip of the shaft21with an adhesive or the like.

The first circuit board80and the second circuit board (circuit board)83are accommodated in the bearing holder52. The first circuit board80and the second circuit board (circuit board)83are located axially above the bus bar assembly60.

The first circuit board80and the second circuit board83extend perpendicularly to the center axis C and are formed in a plate shape. The second circuit board83is located axially above the first circuit board80with a predetermined gap interposed therebetween. When viewed from the axial direction, the first circuit board80and the second circuit board83are located so as to overlap each other.

The lower surface of the first circuit board80and the upper surface of the upper cylindrical portion523aof the bearing holder52axially face each other with a gap interposed therebetween. The first circuit board80and the second circuit board83are electrically connected by connection pins (not illustrated).

The motor cover70is located between the first circuit board80and the upper surface of the upper cylindrical portion523a. The motor cover70is formed in a disk shape and is located axially above the bus bar assembly60. Accordingly, it is possible to prevent dust from adhering to the bus bar assembly60.

The circuit terminal84is connected to the lower surface of the second circuit board83. The circuit terminal84extends axially downward, passes through the inside of the terminal through hole521b, protrudes axially downward from the lower surface of the holder protrusion521a, and is connected to a bus bar terminal65described later. Accordingly, the second circuit board83is electrically connected to the bus bar assembly60. The first circuit board80and the second circuit board83output a motor drive signal to the stator40via the bus bar assembly60.

The sensor81that detects a rotational position of the rotor20is mounted on the lower surface of the first circuit board80. The sensor81is located axially above the sensor magnet91. Therefore, the distance between the sensor81and the sensor magnet91is short, and the magnetoresistance element can be suitably used for the sensor81.

The sensor81detects the magnetic flux of the sensor magnet91to detect the rotational position of the rotor20. As a result, a motor drive signal corresponding to the rotational position of the rotor20is output, and the drive current supplied to the coil portion33is controlled. Therefore, the driving of the motor1can be controlled.

FIGS.6and7are a perspective view and an exploded perspective view of the bus bar assembly60. The bus bar assembly60is electrically connected to the stator30and located on the bearing holder52. The bus bar assembly60is located radially outside of the upper bearing41in the bearing holder52.

The bus bar assembly60includes a bus bar holder61, bus bars62U,63V, and64W, and a bus bar terminal65. The bus bars62U,63V, and64W are formed of plate-like members having conductivity, and have shapes different from each other. The bus bars62U,63V, and64W correspond to the U-phase, the V-phase, and the W-phase, respectively. In the present example embodiment, the bus bar62U corresponds to the U-phase, the bus bar63V corresponds to the V-phase, and the bus bar64W corresponds to the W-phase.

The bus bar62U includes a base portion62a, a connection portion62b, and a terminal portion62c. The base portion62aextends in the circumferential direction and is formed in an arc shape in top view.

The connection portion62bprotrudes radially inward from the radially inner face of the base portion62a, and the distal end portion is bent axially downward. Four connection portions62bare provided and located at equal intervals in the circumferential direction. The connection portion62bhas a conductive wire holding portion621b. The conductive wire holding portion621bprotrudes radially inward from the distal end portion of the connection portion62band is formed in a substantially U shape in top view. The terminal portion62clinearly extends radially outward from the radially outer surface of the base portion62a.

The bus bar63V includes a base portion63a, a connection portion63b, and a terminal portion63c. The base portion63aextends in the circumferential direction and is formed in an arc shape in top view.

The connection portion63bprotrudes radially inward from the radially inner face of the base portion63a, and the distal end portion thereof is bent axially downward. The four connection portions63bare provided and located in the circumferential direction at equal intervals. The connection portion63bhas a conductive wire holding portion631b. The conductive wire holding portion631bprotrudes radially inward from the distal end portion of the connection portion63band is formed in a substantially U shape in top view. The terminal portion63cprotrudes axially upward from the radially outer surface of the base portion63a, and the distal end portion thereof extends and is bent radially outward.

The bus bar64W includes a base portion64a, a connection portion64b, and a terminal portion64c. The base portion64aextends in the circumferential direction and is formed in an arc shape in top view.

The connection portion64bprotrudes radially inward from the radially inner face of the base portion64a, and the distal end portion thereof is bent axially downward. The four connection portions64bare provided and located in the circumferential direction at equal intervals. The connection portion64bhas a conductive wire holding portion641b. The conductive wire holding portion641bprotrudes radially inward from the distal end portion of the connection portion64band is formed in a substantially U shape in top view. The terminal portion64cprotrudes axially upward from the radially outer surface of the base portion64a, and the distal end portion thereof extends and is bent radially outward.

The base portion64a, the base portion63a, and the base portion62aare formed in a thin plate shape and sequentially overlap in the axial direction with a spacer (not illustrated) interposed therebetween. As a result, the bus bar assembly60can be thinned in the axial direction. The spacer is formed of, for example, a material having an insulating property such as resin.

In a state where the base portion64a, the base portion63a, and the base portion62aoverlap, the connection portion62b, the connection portion63b, and the connection portion64bare located in order in the circumferential direction at equal intervals. At this time, the lower end of the connection portion62b, the lower end of the connection portion63b, and the lower end of the connection portion64bare located at substantially the same axial height. In addition, the plurality of connection portions62b,63b, and64bsequentially located in the circumferential direction at equal intervals protrudes radially inward from the radially inner faces of the base portions62a,63a, and64a, respectively, and the bus bar assembly60can be downsized in the radial direction.

The conductive wire holding portions621b,631b, and641bare electrically connected to the distal end portion of the conductive wire33aextending axially upward from the stator30by laser welding or the like. That is, the connection portion62bextends axially downward from the base portion62aand is connected to the conductive wire33a. The connection portion63bextends axially downward from the base portion63aand is connected to the conductive wire33a. The connection portion64bextends axially downward from the base portion64aand is connected to the conductive wire33a.

The bus bar terminal65is formed in an L shape, and one end side thereof extends in the radial direction. One end sides of the plurality of bus bar terminals65are connected and fixed to the terminal portion62c, the terminal portion63c, and the terminal portion64cby welding. Thus, the bus bar terminals65are connected to the bus bars62U,63V, and64W. The other end side of the bus bar terminal65extends axially downward and is electrically connected to the circuit terminal84. The connection structure between the bus bar terminal65and the circuit terminal84will be described in detail later. In the present example embodiment, the bus bar terminal65, the terminal portion62c, the terminal portion63c, and the terminal portion64care formed separately, but the present disclosure is not limited thereto. For example, the terminal portion62cand the bus bar terminal65, the terminal portion63cand the bus bar terminal65, and the terminal portion64cand the bus bar terminal65may be integrally formed.

The bus bar holder61is made of an insulating material such as resin. The bus bar holder61covers the outer surfaces of the bus bars62U,63V, and64W including the base portions62a,63a, and64a, and the terminal portions62c,63c, and64c, and the bus bar terminal65. In the present example embodiment, the bus bars62U,63V, and64W and the bus bar terminals65are embedded in and fixed to the bus bar holder61by insert molding. Thus, the bus bars62U,63V, and64W are insulated from each other via the bus bar holder61.

The bus bar holder61includes a base portion holder61a, a terminal holder61b, and a terminal guide portion61c. The base portion holder61acovers the base portions62a,63a, and64aoverlapping in the axial direction, and is formed in a substantially annular shape when viewed from the axial direction.

The terminal holder61blinearly extends radially outward from the radially outer surface of the base portion holder61a. The three terminal holders61bare provided in the circumferential direction, and covers the terminal portions62c,63c, and64clocated side by side in the circumferential direction and one end, of the bus bar terminal65, extending in the radial direction.

The terminal guide portion61cis connected to the radially outer end of each terminal holder61b. The terminal guide portion61cextends in the axial direction and is formed in a tubular shape. The upper surface and the lower surface of the terminal guide portion61care opened. The terminal guide portion61ccovers the other end, of the bus bar terminal65, extending in the axial direction. As a result, the bus bar terminals65connected to the U-phase, the V-phase, and the W-phase are insulated from each other via the terminal guide portion61c.

Each bus bar terminal65is partially exposed in the inside of the terminal guide portion61cand is not covered by the terminal guide portion61c(seeFIG.8).

The terminal guide portion61chas an opening of a terminal insertion port61dat an upper surface, and an opening of a terminal extraction port61eat a lower surface (seeFIG.8).

FIG.8is an enlarged cross-sectional perspective view illustrating the bus bar terminal65and the circuit terminal84, andFIG.9is an enlarged cross-sectional perspective view illustrating the terminal guide portion61c. The terminal guide portion61cis located inside the terminal through hole521b. The circuit terminal84is inserted into the terminal insertion port61dand comes into contact with the bus bar terminal65. Thus, the bus bar terminal65and the circuit terminal84are electrically connected in the terminal guide portion61c.

The bus bar terminal65and the circuit terminal84pass through the terminal through hole521bin a state of being accommodated in the terminal guide portion61c. Therefore, the bus bar terminal65and the circuit terminal84are reliably insulated from the bearing holder52, and the occurrence of a short circuit can be prevented.

The bus bar terminal65and the circuit terminal84protrude axially downward from the terminal extraction port61e, and the lower end portions of the bus bar terminal65and the circuit terminal84are reliably connected by welding. At this time, the lower ends of the bus bar terminal65and the circuit terminal84are located axially below the lower surface of the bearing holder52. As a result, it is possible to improve work efficiency at the time of welding in a state where the bus bar cover528is removed.

The lower end P of the terminal guide portion61cis located axially below the lower end P of the terminal through hole521b. As a result, the circuit terminal84and the bus bar terminal65can further prevent the occurrence of a short circuit by securing an insulation distance from the bearing holder52.

The terminal guide portion61chas an inclined portion61f. The inclined portion61fof the inner peripheral surface of the terminal guide portion61cis inclined inward as going axially downward from the terminal insertion port61d. As a result, the circuit terminal84can be smoothly guided from the terminal extraction port61eto the inside of the terminal guide portion61calong the inclined portion61f. Therefore, work efficiency of assembling the motor1and the second circuit board83is improved. In addition, by making the terminal insertion port61dlarge, even when the lower end portion of the circuit terminal84is shifted in the radial direction or the circumferential direction at the time of insertion, it is possible to reliably guide the circuit terminal into the terminal guide portion61c.

FIG.10is a perspective view of the bus bar cover528. The bus bar cover528is, for example, a resin molded article. The bus bar cover528is attached after the lower end portions of the circuit terminal84and the bus bar terminal65are welded. Accordingly, it is possible to prevent the welded lower end portions of the circuit terminal84and the bus bar terminal65from being exposed to the outside of the bearing holder52.

The bus bar cover528includes a tubular cover portion528aand a flange portion528b. The cover portion528acovers the lower end portions of the bus bar terminal65and the circuit terminal84, and has an open upper surface. The flange portion528bextends outward from the upper end peripheral edge portion of the cover portion528aand is fixed to the lower surface of the holder protrusion521a.

The flange portion528bincludes a flange projection528cand a pair of fixing pins528d. The flange projection528cprotrudes axially upward from the upper surface of the flange portion528b, and is formed in an annular shape surrounding the opening of the cover portion528a.

The flange projection528cincludes a plurality of outer protrusions5281cand a plurality of inner protrusions5282c. The outer protrusion5281cprotrudes outward from the outer peripheral surface of the flange projection. The inner protrusion5282cprotrudes inward from the inner peripheral surface of the flange projection.

The pair of fixing pins528dprotrudes axially upward from the upper surface of the flange portion528b, and is located with the flange projection528cinterposed therebetween.

The holder protrusion521aincludes a seal recess521cand a fixing recess521d(seeFIG.8). The fixing recess521dis recessed axially upward from the lower surface, and the fixing pins528dare located inside. By press-fitting the fixing pins528dinto the fixing recess521d, the bus bar cover528can be easily fixed to the lower surface of the holder protrusion521a. Therefore, work efficiency of assembling the motor1is improved.

The holder protrusion521ais made of metal, and the bus bar cover528is made of resin. Therefore, the fixing pin528dis hardly deteriorated by rust or the like, and the bus bar cover528can be fixed to the lower surface of the holder protrusion521a. In addition, the resin has a thermal expansion coefficient larger than that of metal. Therefore, even when the motor1has a high temperature, it is possible to maintain a state in which the fixing pin528dis fixed in the fixing recess521d.

The seal recess521cis recessed axially upward from the lower surface of the holder protrusion521aand is formed in an annular shape surrounding the terminal through hole521b. The flange projection528cis located inside the seal recess521cfilled with the seal material. As a result, the sealability between the upper surface of the flange portion528band the lower surface of the holder protrusion521ais improved. Therefore, the waterproof property can be improved.

In addition, for example, when the fixing pin528dis broken, there is a possibility that the walls of the bus bar cover528and the bearing holder52filled with the seal material come into contact with each other and there is no gap therebetween. At this time, a portion where the seal material cannot be interposed is formed. However, since the outer protrusion5281cand the inner protrusion5282care formed, even if the bus bar cover528comes into contact with the bearing holder52, the contact is a line contact and a gap is formed. Therefore, the seal material can be interposed, and it is possible to suppress a decrease in sealability between the upper surface of the flange portion528band the lower surface of the holder protrusion521a.

The lower end61eof the terminal guide portion61cis located axially below the lower end P of the terminal through hole521b. Therefore, coming from the seal recess521cis blocked by the terminal guide portion61c, and it is possible to prevent the seal material adhering to the lower end portions of the bus bar terminal65and the circuit terminal84.

In the present example embodiment, the seal material is an adhesive, and the bus bar cover528is fixed to the peripheral wall portion522of the bus bar holder52together with the sealing function. In addition, in a case where an adhesive is used, it takes time for the adhesive to be reliably fixed, and thus the fixing pins528dare press-fitted into the fixing recess521dto function as a temporary fixing. With such a configuration, a state where the bus bar cover528is positioned with respect to a bus bar holder52can be maintained. Further, a plurality of crush ribs extending in the axial direction is formed on the outer periphery of the fixing pins528.

The example embodiments described above are merely examples of the present disclosure. The configuration of the example embodiments may be appropriately changed without departing from the technical idea of the present disclosure. In addition, the example embodiment and the plurality of modifications may be may be implemented in combination within a feasible range. In the present example embodiment, the plurality of outer protrusions5281cand the plurality of inner protrusions5282care provided, but one of them may be omitted. Further, only one outer protrusion5281cor only one inner protrusion5282cmay be provided.

The motor of the present disclosure can be used for an electric power steering device used for assisting steering wheel operation of a vehicle such as an automobile. The present disclosure is suitable for, for example, a power steering device, but can also be used for other devices such as a blower.

Features of the above-described example embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.