Motor and method for manufacturing motor

A brush holder is held between a flange of a yoke housing and a gear housing of a speed reduction unit and fastened by a fastening screw. A link of the brush holder is located between a screw fastening portion of the flange and a screw fastening portion of the gear housing. A connector is linked to a holder main body by the link. The link includes a screw insertion hole and first and second bridges. A metal terminal, which electrically connects the holder main body and the connector, is embedded in each of the first and second bridges.

RELATED APPLICATION

This application claims benefit of priority of Japanese Application No. 2013-193151, filed Sep. 18, 2013, said application being hereby fully incorporated herein by reference.

BACKGROUND

The present invention relates to a motor incorporating a speed reduction mechanism and including a brush holder and a method for manufacturing the motor.

Japanese Laid-Open Patent Publication No. 2012-244851 describes prior art example of a motor incorporating a speed reduction mechanism that includes a motor main body, which includes a yoke housing, and a speed reduction unit, which includes a gear housing. When a resin brush holder is held between a flange of the yoke housing and the gear housing, screws tightly fasten a screw fastening portion of the flange and a fastening portion of the gear housing. The brush holder includes a holder main body that holds a power supplying brush, a connector used for external connection, and a link that links the holder main body and the connector.

There is a need to flatten the profile of such a motor in the direction orthogonal to the axial direction. Therefore, the connector of the brush holder extends in the same direction as the direction in which the screw fastening portions of the flange and the gear housing extend. That is, the link, which links the holder main body and the connector, is located between the screw fastening portions. Thus, a slot is formed in the link to avoid the screw. This narrows the link and lowers the rigidity of the brush holder.

SUMMARY

It is an object of the present invention to provide a motor that flattens the profile of the motor in a direction orthogonal to the axial direction and improves the rigidity of the brush holder at the link between the holder main body and the connector and to provide a method for manufacturing a motor.

To achieve the above object, a motor according to one aspect of the present invention includes a motor main body, a speed reduction unit, and a brush holder. The motor main body includes a yoke housing including a flange. The flange includes a screw fastening portion. The speed reduction unit includes a gear housing. The gear housing includes a screw fastening portion. The brush holder is formed from a resin. The brush holder is held between the flange and the gear housing and fastened by a fastening screw. The brush holder includes a holder main body that holds a power supplying brush, a link extending from the holder main body so that the link is located between the screw fastening portion of the flange and the screw fastening portion of the gear housing, and a connector linked to the holder main body by the link and used for external connection. The link includes a screw insertion hole, through which the fastening screw is inserted, and first and second bridges arranged at opposite sides of the screw insertion hole. The first and second bridges connect the holder main body and the connector. A metal terminal, which electrically connects the holder main body and the connector, is embedded in each of the first and second bridges.

DESCRIPTION OF THE EMBODIMENTS

One embodiment of a motor will now be described.

As shown inFIG. 1, a motor10of the present embodiment is used as a driving source for a vehicle power window. The motor10includes a motor main body11and a speed reduction unit12, which reduces the rotation speed of the motor main body11.

A yoke housing13of the motor main body11includes a cylindrical main body, a closed end, an open end, and a flange14. The flange14extends from the open end toward the outer side in the radial direction. The flange14is flat and orthogonal to the axial direction. A field magnet15is fixed to the inner circumference surface of the yoke housing13. A rotor16is located at the inner side of the field magnet15.

A rotor core18and a commutator19are fixed to a rotation shaft17of the rotor16so that the rotor core18and the commutator19are rotatable integrally with each other. A winding wire18ais wound around the rotor core18. An end of the winding wire18ais connected to the commutator19. In the yoke housing13, the rotor core18is opposed to the field magnet15in the radial direction. A distal end of the rotation shaft17projects out of the yoke housing13through the open end of the yoke housing13, that is, the end of the yoke housing13where the flange14is arranged.

A gear housing21of the speed reduction unit12is fixed to the flange14of the yoke housing13with a resin brush holder22held in between. A speed reduction mechanism (not shown), which reduces the rotation speed of the rotation shaft17, is accommodated in the gear housing21. An output gear23is rotatably supported by the gear housing21. The speed reduction mechanism transmits the rotation of the rotation shaft17to the output gear23. The output gear23is coupled to a vehicle window glass by a window regulator (not shown).

As shown inFIG. 2A, the yoke housing13and the gear housing21function as a case of the motor10. The case is flat and thin in the direction orthogonal to the axis L of the rotation shaft17(up-down direction inFIG. 2A). Hereinafter, when viewing the motor10from above, the direction in which the long sides extend (left-right direction inFIG. 2A) is referred to as the motor longitudinal direction, and the direction in which the short sides extend (up-down direction inFIG. 2A) is referred to as the motor lateral direction. The axial direction (direction of the axis L), the longitudinal direction, and the lateral direction of the motor10are orthogonal to one another.

The flange14includes a first extension24and a second extension25extending from the two sides of the cylindrical main body in the motor longitudinal direction. The first extension24includes one through hole24ain the central portion in the motor lateral direction. The second extension25includes two through holes25a. The through holes25aare arranged in the second extension25proximate to the two edges in the motor lateral direction. Fastening screws26are inserted through the through holes24aand25aand fastened to a yoke attachment21aof the gear housing21.

The brush holder22includes a holder main body31, a connector32used for external connection, and a link33located between the holder main body31and the connector32.

As shown inFIG. 1, a portion of the holder main body31is fitted in the yoke housing13. The holder main body31holds a power supplying brush34, which contacts the commutator19.

As shown inFIG. 2B, the holder main body31is shaped in correspondence with the flat shape of the yoke housing13. An elastomeric seal member35is formed integrally with the outer circumferential edge of the holder main body31. The seal member35is held between the flange14of the yoke housing13and the yoke attachment21aof the gear housing21in the axial direction. The seal member35is attached to the flange14and the yoke attachment21aand compressed by the fastening force of the fastening screw26. This seals the opening. of the yoke housing13and the yoke attachment21ain a liquid-tight manner. A bearing (not shown), which axially supports the rotation shaft17, is arranged in the center of the holder main body31.

The link33of the brush holder22extends from the holder main body31so that the link33of the brush holder22is located between a screw fastening portion24bof the first extension24and a screw fastening portion21bof the yoke attachment21a. More specifically, the link33includes a first bridge36and a second bridge37, which connect the holder main body31and the connector32. The first and second bridges36and37extend from the holder main body31in the motor longitudinal direction that is the same as the direction in which the first extension24extends from the main body of the yoke housing. The first and second bridges36and37are located at opposite sides in the motor lateral direction. The first and second bridges36and37are covered by the seal member35extending from the holder main body31.

A screw insertion hole38, through which the fastening screw26of the first extension24is inserted, is arranged between the first and second bridges36and37. The screw insertion hole38is arranged in the laterally central portion (central portion in the motor lateral direction) of the link33. That is, the first and second bridges36and37have the same length in the motor lateral direction. The screw insertion hole38is tetragonal as viewed in the axial direction.

The connector32, which is integrally connected to the holder main body31by the first and second bridges36and37, is located beside the yoke housing13in the motor longitudinal direction.

Two power supplying terminals39aand39b, which are power terminals, are insert-molded and embedded in the brush holder22. Portions of the power supplying terminals39aand39bclose to the holder main body31are electrically connected to the power supplying brush34. One of the power supply terminals39ais laid out from the holder main body31through the first bridge36to the connector32. The other one of the power supply terminals39bis laid out from the holder main body31through the second bridge37to the connector32.

The connector32includes an external connection opening32a, which upwardly opens in the axial direction. The ends of the power supply terminals39aand39bclose to the connector32are exposed to the space in the external connection opening32a. The power supply terminals39aand39bare electrically connected to an external connector (not shown), which is fitted to the external connection opening32ain the axial direction. This allows for power supply to the power supplying brush34from the external connector through the power supply terminals39aand39b.

The brush holder22is molded as follows. First, injection molding is performed to integrally mold the power supply terminals39aand39b, which serves as inserts, with the brush holder (insert molding step). The power supply terminals39aand39bare connected to each other by a connecting portion (not shown). The connecting portion connecting the power supply terminals39aand39bis located at a position corresponding to the screw insertion hole38of the link33.

Subsequently, the connecting portion exposed in the screw insertion hole38of the link33is cut. This electrically insulates the power supply terminals39aand39bfrom each other (connecting portion cutting step).

Then, the seal member35is formed from the outer circumferential edge of the holder main body31to the first and second bridges36and37. The cut location of the connecting portion is covered by the seal member35, which covers the first and second bridges36and37. Thus, the cut location of the connecting portion is not exposed in the screw insertion hole38.

The first and second extensions24and25(flange14) of the yoke housing13are fastened to the gear housing21by the fastening screws26. The first and second extensions24and25extend in the motor longitudinal direction. The connector32of the brush holder22is located at a position separated from the yoke housing13in the same direction as the direction in which the first extension24(screw fastening portion24b) extends from the yoke housing13. This flattens the motor10in the direction orthogonal to the axis.

The holder main body31is coupled to the connector32by the first and second bridges36and37arranged at the two sides of the screw insertion hole38in the motor lateral direction. This improves the rigidity of the link33as compared with a structure that has a slot in the link33between the holder main body31and the connector32to avoid interference with the screw. That is, the rigidity of the link33is improved as compared with a structure that connects the holder main body31and the connector32at a single location. Additionally, the metal power supply terminals39aand39bare respectively embedded in the first and second bridges36and37. This further improves the rigidity of the first and second bridges36and37.

In the present embodiment, the through hole24a, into which the fastening screw26is inserted, is formed in the center of the first extension24(flange14) in the motor lateral direction. Thus, the yoke housing13is symmetric in the motor lateral direction. This allows the yoke housing13to be applied to brush holders having different structures without changing the shape of the yoke housing13. For example, in a vehicle power window device, without changing the shape of the yoke housing13, the yoke housing13may be applied to a brush holder including connectors that can be connected in any one of two opposite motor lateral directions in correspondence with the driver seat side and the passenger seat side (right and left sides). This improves the versatility of the yoke housing13.

The present embodiment has the advantages described below.

(1) The link33of the brush holder22includes the screw insertion hole38, through which the fastening screw26is inserted, and the first and second bridges36and37, which are located at opposite sides of the screw insertion hole38. The first and second bridges36and37connect the holder main body31and the connector32. In this manner, the connector32extends from the holder main body31in the same direction as the direction in which the screw fastening portion24b(first extension24) extends from the yoke housing13. This improves the rigidity of the link33while flattening the motor10in the direction orthogonal to the axis. Further, in the present embodiment, the power supply terminals39aand39b(metal terminals), which electrically connect the holder main body31and the connector32, are respectively embedded in the first and second bridges36and37. This improves the rigidity of the first and second bridges36and37. Consequently, the rigidity of the link33may be further improved.

(2) The screw insertion hole38of the brush holder22is arranged in the laterally central portion (central portion in the motor lateral direction) of the link33. This structure allows the first and second bridges36and37to have the same width. Thus, the rigidity of the link33may be improved in a well-balanced manner. The screw insertion hole38and the through hole24aare located in the laterally central portion of the first extension24(flange14). Thus, the yoke housing13, which includes the through hole24athat is located at the same position, is applicable to various types of the brush holder22including the connector32that can be connected in different directions. This is advantageous for improving the versatility of the yoke housing13.

(3) The metal terminals embedded in the first and second bridges36and37are the power supply terminals39aand39b, which are power terminals that supply current to the power supplying brush34. More specifically, the power supply terminals39aand39b, which have relatively large cross-sectional areas, are embedded in the first and second bridges36and37. This further improves the rigidity of the first and second bridges36and37.

(4) The brush holder22is insert-molded. Then, the connecting portion, which connects the power supply terminals39aand39b, is cut through the screw insertion hole38. This prevents displacement of the power supply terminals39aand39bembedded in the brush holder22. Additionally, the screw insertion hole38of the brush holder22also serves as a hole used when cutting the connecting portion. This simplifies the structure of the brush holder22. Additionally, the cut location of the connecting portion is covered with the seal member35, which covers the first and second bridges36and37. Thus, the cut location of the connecting portion is not exposed in the screw insertion hole38.

The above embodiment may be modified as described below.

The brush holder22of the above embodiment may be modified, for example, to a brush holder41shown inFIGS. 3 to 4B.

A connector42of the brush holder41is integrated with a board accommodation housing43. The board accommodation housing43extends from the holder main body31in the motor longitudinal direction that is the same direction as the direction in which the first extension24extends from the yoke housing13. The board accommodation housing43accommodates a control circuit board (not shown), which controls the driving of the motor10. The control circuit board is arranged to extend in a direction generally orthogonal to the motor lateral direction. An end portion of the connector42in the motor longitudinal direction is fastened to the gear housing21by a screw44.

As shown inFIGS. 3 and 4A, an external connecting portion42a, which opens upwardly in the axial direction, is defined on the axially upper end surface (end surface opposing to gear housing) of the board accommodation housing43. The external connecting portion42aincludes a plurality of connection terminals42b. One end of the connection terminal42bis connected to the control circuit board, and the other end of the connection terminal42bis exposed in the external connecting portion42a. Each of the connection terminals42bis electrically connected to an external connector (not shown), which is connected to the external connecting portion42a. As shown inFIG. 4A, due to spatial limitations imposed on the layout of the motor, a laterally end surface, that is, the upper end surface inFIG. 4A, of the board accommodation housing43is tilted with respect to the motor longitudinal direction.

As shown inFIG. 4B, the brush holder41includes a link45arranged between the holder main body31and the connector42. The link45extends from the holder main body31so that the link45is located between the screw fastening portion24bof the first extension24(flange14) and the screw fastening portion21bof the yoke attachment21a. More specifically, the link45includes first and second bridges46and47, which connect the holder main body31and the connector42. The first and second bridges46and47extend from the holder main body31in the motor longitudinal direction that is the same direction as the direction in which the first extension24extends from the main body of the yoke housing. The first and second bridges46and47are arranged facing each other in the motor lateral direction.

A screw insertion hole48, through which the fastening screw26of the first extension24is inserted, is arranged between the first and second bridges46and47. The screw insertion hole48is arranged in the laterally central portion (central portion in the motor lateral direction) of the link45. That is, the first and second bridges46and47have the same length in the motor lateral direction. The screw insertion hole48is tetragonal as viewed in the axial direction.

An elastomeric seal member49, which seals the openings of the yoke housing13and the yoke attachment21a, is integrated with the brush holder41. The seal member49is arranged in the outer circumferential edge of the holder main body31, the inner circumferential edge, and the circumferential portion of the axially lower end (end that is closer to gear housing21) of the board accommodation housing43.

Two power supply terminals50aand50b, which are power terminals, are insert-molded and embedded in the brush holder41. The power supplying brush34(refer toFIG. 3) is electrically connected to the power supply terminals50aand50bat portions closer to the holder main body31. One of the power supply terminals50ais laid out from the holder main body31through the first bridge46to the connector42. The other one of the power supply terminals50bis laid out from the holder main body31through the second bridge47to the connector42.

In the same manner as the above embodiment, when the brush holder41undergoes insert molding, the power supply terminals50aand50bare connected to each other by the connecting portion. After the insert molding, the connecting portion is cut through the screw insertion hole38. The cut location of the connecting portion is covered with the seal member49arranged in the inner circumferential edge of the screw insertion hole38.

The structure shown inFIGS. 3 and 4obtains the same advantages as the above embodiment.

In the above embodiment and the example shown inFIGS. 3 and 4, the metal terminals embedded in the first and second bridges36and37(first and second bridges46and47) are used as the power supply terminals39aand39b(power supply terminals50aand50b), which supply current to the power supplying brush34. Terminals other than the power supply terminals39aand39bmay be embedded in the first and second bridges36and37(first and second bridges46and47).

In the above embodiment and the example shown inFIGS. 3 and 4, the screw insertion hole38(screw insertion hole48) is arranged in the central portion of the link33(link45) in the motor lateral direction. The screw insertion holes38and48do not have to be arranged in the laterally central portions of the links33and45as long as the first bridges36and46and the second bridges37and47are included.