MOTOR DEVICE AND OIL PUMP DEVICE

A motor device includes an electric motor, a control board on which a control circuit controlling the electric motor is mounted, a metal housing supporting a first surface of the control board, a resin cover attached to the housing to cover a second surface of the control board opposite to the first surface and the periphery of the control board, and a heat dissipation member dissipating heat generated by a heating element included in the control circuit to the housing. The heat dissipation member includes a heat reception plate fixed to the cover, and a heat transfer plate protruding toward the housing. The housing includes, outside the motor accommodation space, a reception portion receiving a protrusion end of the heat transfer plate inserted in a direction in which a rotation shaft extends, and a heat exhaust wall extending in the and coming into surface contact with the heat transfer plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of Japanese application no. 2023-109547, filed on Jul. 3, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The disclosure relates to a motor device and an oil pump device having the same mounted thereon.

Description of Related Art

In recent years, efforts have been made to promote sustainable development goals (2030 Agenda for Sustainable Development, adopted by the United Nations Summit on Sep. 25, 2015; hereinafter referred to as “SDGs”). In addition, a technology aiming at greatly reducing generation of waste through waste prevention, waste reduction, and product recycling and reuse in order to ensure sustainable production and consumption patterns is known.

In the related art, a so-called “mechanical and electrical integrated type” motor device in which an electric motor and a control board for controlling the electric motor are accommodated in a housing and integrated is known. Further, such a motor device is provided with a heat sink that exhausts, through the housing, heat emitted from a control circuit mounted on the control board.

For example, Patent Document 1 discloses a motor device in which a heat sink is fixed to the outer side of a motor accommodation space of a housing with bolts. More specifically, the heat sink of Patent Document 1 has one surface in a thickness direction in surface contact with a control board, and the other surface in the thickness direction in surface contact with an attachment surface of the housing perpendicular to a rotation axis of the motor.

PATENT DOCUMENTS

However, since there is little space outside the motor accommodation space of the housing, it is difficult to secure a large attachment surface. As a result, since a contact area between the heat sink and the housing cannot be increased, it is difficult to improve heat exhaust efficiency. On the other hand, it is necessary to increase a size of the motor device in a radial direction in order to improve the heat exhaust efficiency with the motor device of Patent Document 1.

Therefore, the disclosure provides a technology for improving the efficiency of exhausting heat emitted from a control circuit without increasing a size of a motor device.

SUMMARY

The disclosure is a motor device including: an electric motor; a control board on which a control circuit for controlling the electric motor is mounted; a metal housing having a motor accommodation space for accommodating the electric motor and supporting a first surface of the control board at a position offset in a direction in which a rotation shaft of the electric motor extends from the motor accommodation space; a resin cover attached to the housing to cover a second surface of the control board opposite to the first surface and the periphery of the control board; and a heat dissipation member configured to dissipate heat generated by a heating element included in the control circuit to the housing, wherein the heat dissipation member includes a heat reception plate fixed to the cover at a position facing the heating element; and a heat transfer plate protruding toward the housing from the heat reception plate at a position away from the control board, and the housing includes, outside the motor accommodation space, a reception portion configured to receive a protrusion end of the heat transfer plate inserted in the direction in which the rotation shaft extends; and a heat exhaust wall extending in the direction in which the rotation shaft extends and coming into surface contact with the heat transfer plate received in the reception portion.

DESCRIPTION OF THE EMBODIMENTS

According to the disclosure, it is possible to improve the efficiency of exhausting heat emitted from the control circuit without increasing a size of the motor device. Problems, configurations, and effects other than those described above will be made clear by the following description of the embodiments.

Hereinafter, an oil pump device1according to an embodiment of the disclosure will be described with reference to the drawings.FIG.1is an external perspective view of the oil pump device1according to the present embodiment.

The oil pump device1according to the present embodiment supplies oil (for example, lubricating oil) to an engine clutch or a transmission mechanism clutch mounted on, for example, an automobile. However, the use of the oil pump device1is not limited thereto.

As shown inFIG.1, the oil pump device1is a so-called “electric oil pump” including a motor unit2, a control unit3, and a pump unit4. Further, the motor unit2and the control unit3constitute a so-called “mechanical and electrical integrated type” motor device5independently of the pump unit4. The motor device5is not limited to driving the pump unit4, and may also drive a cooling fan or a wiper.

The motor unit2includes an electric motor6(seeFIG.7) that rotates (generates a driving force) according to a driving power supplied from the control unit3. Although a specific example of the electric motor6is not particularly limited, for example, an inner rotor type brushless motor can be adopted. Since a configuration of the electric motor6is already well known, detailed description will be omitted. The control unit3supplies a power supplied from an external device (not shown) to the electric motor6as a drive power. A specific configuration of the control unit3will be described later with reference toFIG.2and subsequent figures. The pump unit4receives the driving force of the motor unit2and pumps oil. Since a configuration of the pump unit4is already well known, detailed description thereof will be omitted.

The motor unit2, the control unit3, and the pump unit4are disposed adjacent to each other in a direction in which a rotation shaft7(seeFIG.7) of the electric motor6, which will be described later, extends. More specifically, the control unit3is disposed adjacent to one side of the rotation shaft7in the extending direction with respect to the motor unit2disposed at a center, and the pump unit4is disposed adjacent to the other side of the rotation shaft7in the extending direction.

The oil pump device1includes the housing10that accommodates the motor unit2, the control unit3, and the pump unit4. The housing10is made of, for example, a metal material such as die-cast aluminum. The housing10is not limited to an integral type in which the motor unit2, the control unit3, and the pump unit4are collectively accommodated, and may be constructed in parts as separate bodies.

FIG.2is an exploded perspective view of the control unit3.FIG.3is a perspective view of the control unit3in a state where a cover60has been removed. As shown inFIGS.2and3, the control unit3mainly includes the housing10, a control board20, a connector unit30, a relay unit40, a heat sink50, and the cover60. Hereinafter, the extending direction of the rotation shaft7will be simply referred to as an “axial direction”, and a direction perpendicular to the extending direction of the rotation shaft7(a radial direction of the rotation shaft7) will simply be referred to as a “radial direction”.

As shown inFIG.2, a motor accommodation space11that accommodates the electric motor6is formed in the housing10. The motor accommodation space11is a space having a generally cylindrical external shape. Furthermore, the housing10includes a support surface12that supports components (20to60) of the control unit3. The support surface12is a surface that stretches in the radial direction at a position offset in the axial direction from the motor accommodation space11. The support surface12has a generally rectangular external shape when viewed from the axial direction.

On the support surface12, a plurality of (in the present embodiment, four) support protrusions13a,13b,13c, and13d, a plurality of (in the present embodiment, four) screw seats14a,14b,14c, and14d, and a heat sink support portion15are provided.

The support protrusions13ato13dprotrude in the axial direction from the support surface12at different positions on the support surface12(typically, positions surrounding the motor accommodation space11). The support protrusions13ato13dsupport the control board20at tips thereof. Furthermore, second positioning holes16a,16b,16c, and16dthat receive positioning pins64ato64d, which will be described later, are formed in the support protrusions13ato13d. The second positioning holes16ato16dextend toward base ends from tips of the support protrusions13ato13d.

The screw seats14ato14dprotrude in the axial direction from the support surface12at different positions on the support surface12(typically, positions surrounding the motor accommodation space11). Screw holes17a,17b,17c, and17dcommunicating with screw holes65ato65dof the cover60when the cover60is attached to the housing10are formed in the screw seats14ato14d. The cover60is fixed to the housing10by screwing the screws18ato18dinto the communicating screw holes17ato17dand65ato65d.

The heat sink support portion15supports an end portion of the heat sink50. The heat sink support portion15is provided at a position radially away from the motor accommodation space11. Further, the heat sink support portion15is provided linearly in parallel with one of four sides constituting an outer edge of the support surface12at a position adjacent to the side. A specific configuration of the heat sink support portion15will be described later with reference toFIGS.6A and6B.

The control board20includes a board21. The board21is a flat member having a generally rectangular external shape. Further, the board21has a first surface21aand a second surface21b(seeFIG.7). The first surface21ais a surface on one side of the board21in the thickness direction (a side facing the motor accommodation space11). The second surface21bis the other surface of the board21in the thickness direction (the side opposite to the first surface21a). As shown inFIGS.6A and6B, the board21is disposed to overlap the motor accommodation space11when viewed from the axial direction. Further, an outer edge portion of the board21is located outside the motor accommodation space11when viewed from the axial direction.

First positioning holes22a,22b,22c, and22dpenetrating in the thickness direction are formed in the board21. The first positioning holes22ato22dare formed at positions corresponding to the support protrusions13ato13dat the outer edge portion of the board21. When the board21is supported by the tips of the support protrusions13ato13d, the first positioning holes22ato22dand the second positioning holes16ato16dcorresponding thereto communicate with each other. When the positioning pins64ato64dare inserted into the first positioning holes22ato22dand the second positioning holes16ato16dcorresponding thereto, the housing10, the control board20, and the cover60are positioned.

A plurality of circuit elements23aand23bconstituting a control circuit23that controls the electric motor6are mounted on one or both of the first surface21aand the second surface21bof the board21. Furthermore, at least a portion (for example, the circuit element23b) of the circuit elements23aand23bis a heat generation element that generates a large amount of heat. The circuit element23bis mounted on the second surface21bof the board21near the side (the left side inFIG.3) different from the side (the right side inFIG.3) where the connector unit30is disposed and the side (the top side inFIG.3) where the relay unit40is disposed among the four sides constituting the outer edge of the board21.

The connector unit30connects the external device to the control circuit23. The connector unit30includes a pair of power lines for supplying a drive power output from the external device to the control circuit23, and a pair of signal lines for transmitting and receiving control signals between the external device and the control circuit23. The connector unit30is housed in a connector holder63of the cover60. The connector unit30, for example, is inserted and integrally molded when the cover60is injection molded. The relay unit40connects the control circuit23to the electric motor6(more specifically, a coil). The relay unit40supplies the drive power output from the control circuit23to the coil. Accordingly, the electric motor6rotates.

FIGS.4A and4Bare perspective view of the heat sink50. The heat sink50is a heat dissipation member that radiates heat generated by a circuit element23bto the housing10. The heat sink50is formed of a metal material with high thermal conductivity (for example, copper). For example, when a flat plate is pressed, the heat sink50is formed in a shape shown inFIGS.4A and4B.

As shown inFIGS.4A and4B, the heat sink50includes a heat reception plate51and the heat transfer plate52. The heat sink50is bent so that the heat reception plate51and the heat transfer plate52intersect (are orthogonal to) each other. That is, the heat sink50has a generally L-shaped external shape. Further, a protrusion end53(an end portion opposite to the heat reception plate51) of the heat transfer plate52is bent into a U-shape (or J-shape) by a tip of the heat transfer plate52being folded back toward the heat reception plate51. Furthermore, a slit54extending toward the heat reception plate51from the protrusion end53is formed in the heat transfer plate52.

FIG.5is a perspective view of the cover60viewed from the back side. The cover60is integrally molded, for example, by injection molding a resin material. That is, the cover60is formed of a material that has a lower thermal conductivity than the housing10and is lighter than the housing10. As shown inFIGS.2and5, the cover60mainly includes a ceiling wall61, a side wall62, the connector holder63, and a plurality of positioning pins64a,64b,64c, and64d.

The ceiling wall61is a portion that covers the second surface21bof the control board20(board21). When the cover60is attached to the housing10, the ceiling wall61faces the second surface21bat a predetermined interval in the axial direction from the control board20. Further, the heat reception plate51of the heat sink50is attached to a surface (back surface) of the ceiling wall61facing the second surface21b. The heat reception plate51, for example, may be attached to the ceiling wall61by thermal caulking, or may be inserted when the cover60is injection molded. Furthermore, screw holes65a,65b,65c, and65dpenetrating in the thickness direction are formed at four corners of the ceiling wall61.

The side wall62is a frame-shaped portion that covers the periphery of the control board20. The side wall62protrudes toward the housing10from an outer edge portion of the ceiling wall61(that is, in the axial direction). When the housing10is attached to the cover60, a tip of the side wall62abuts the support surface12of the housing10. Accordingly, a board accommodation space24for housing the control board20is formed between the housing10and the cover60(more specifically, the support surface12, the ceiling wall61, and the side wall62). The connector holder63is provided outside the side wall62to hold the connector unit30.

The positioning pins64ato64dprotrude in the axial direction from the back surface of the ceiling wall61inside the side wall62. When the positioning pins64ato64dare inserted into the first positioning holes22ato22d, the control board20in a state where the second surface21bis directed to the ceiling wall61is attached to the cover60. When the positioning pins64ato64dare inserted into the second positioning holes16ato16din this state, the screw holes17ato17dand65ato65dcommunicate with each other, and the protrusion end53of the heat transfer plate52is inserted into a groove15dof the heat sink support portion15in the axial direction, as will be described later. The screws18ato18dare screwed into the communicating screw holes17ato17dand65ato65din a state where the housing10, the control board20, the heat sink50, and the cover60are positioned, so that the cover60is attached to the housing10.

FIGS.6A and6Bare cross-sectional views showing before and after the protrusion end53of the heat transfer plate52is inserted into the groove15dof the heat sink support portion15.FIG.7is a cross-sectional view showing a positional relationship among the heat sink support portion15, the control board20, and the heat sink50.

As shown inFIGS.6and7, the heat sink support portion15includes a base portion15a, a heat exhaust wall15b, and an opposing wall15c. The base portion15ais a portion supported by the support surface12. The heat exhaust wall15band the opposing wall15cextend in the axial direction (that is, toward the cover60) from the base portion15aat a predetermined interval therebetween in a thickness direction of the heat transfer plate52. Further, the base portion15a, the heat exhaust wall15b, and the opposing wall15cextend in the width direction in the heat transfer plate52along the support surface12.

A groove15dis defined by the base portion15a, the heat exhaust wall15b, and the opposing wall15c. The groove15dis an example of a reception portion that receives the protrusion end53of the heat transfer plate52inserted in the axial direction. The groove15dextends linearly in a direction perpendicular to the thickness direction of the heat transfer plate52on the support surface12. However, a shape of the groove15dis not limited thereto, and the groove15dmay be bent along an outer periphery of the motor accommodation space11.

As shown inFIG.6A, a diameter D1of the bent protrusion end53in a natural state is larger than a width dimension D2of the groove15d. Here, the natural state of the protrusion end53is a state where no external force other than gravity is applied (typically, a state before the protrusion end53is inserted into the groove15d). Further, the width dimension D2of the groove15dcorresponds to an interval between the heat exhaust wall15band the opposing wall15c. As shown inFIG.6B, the bent protrusion end53is inserted into the groove15din an elastically contracted state. When the protrusion end53is inserted into the groove15d, the heat transfer plate52and the heat exhaust wall15bcome into surface contact with each other.

As shown inFIG.7, the heat reception plate51faces the second surface21b(more specifically, the circuit element23b) of the control board20at a predetermined interval therefrom in the axial direction. In other words, the heat reception plate51and the control board20are disposed in parallel with each other at a predetermined distance therebetween in the axial direction. Furthermore, a heat dissipation agent55is interposed between the heat reception plate51and the circuit element23b. In other words, the heat reception plate51is in contact with the circuit element23bvia the heat dissipation agent. The heat dissipation agent55is made of, for example, a thermosetting resin with high thermal conductivity.

Further, as shown inFIG.7, the heat transfer plate52protrudes toward the housing10(more specifically, the heat sink support portion15) from the heat reception plate51at a position away from the control board20. More specifically, the heat transfer plate52protrudes toward the housing10while facing a side (the left side inFIG.2) closest to the circuit element23bamong a plurality of sides defining the outer edge of the control board20. Furthermore, the slit54extends to a position closer to the heat reception plate51than the heat exhaust wall15b.

According to the embodiment, for example, the following effects are achieved.

According to the embodiment, the heat exhaust wall15band the heat transfer plate52extending in the axial direction are brought into surface contact with each other to radiate the heat generated by the circuit element23bto the housing10. Here, since a size in the axial direction of the board accommodation space24inherently has a margin corresponding to heights of the circuit elements23aand23bmounted on the board21and heights of the support protrusions13ato13d, it is easy to increase a contact area between the heat exhaust wall15band the heat transfer plate52.

This makes it possible to improve the efficiency of exhausting the heat released from the control circuit23without increasing a size of the oil pump device1(motor device5), as compared to Patent Document 1. As a result, since deterioration of the control circuit23due to heat is curbed, this contributes to extension of the life of the oil pump device1(motor device5) and to prevention of the generation of waste. Furthermore, since it is possible to reduce a weight of the oil pump device1as compared to with a cover made of metal by adopting the cover60made of a resin, this can contribute to carbon neutrality.

Furthermore, according to the embodiment, it is possible to prevent the protrusion end53of the heat transfer plate52from getting caught at the time of entering the groove15dby forming the protrusion end53of the heat transfer plate52in a bent shape. As a result, it is possible to smoothly attach the heat sink50(in other words, the cover60) to the housing10. However, the shape of the protrusion end53is not limited to a bent shape.

Further, according to the embodiment, the diameter D1of the protrusion end53in a natural state is made larger than the width D2of the groove15d, and the protrusion end53is inserted into the groove15dwhile being elastically contracted. Accordingly, since the heat transfer plate52comes into close contact with the heat exhaust wall15bdue to an elastic return force of the protrusion end53, the heat exhaust efficiency is further improved. However, a relationship between D1and D2is not limited to the above-described example.

Furthermore, according to the embodiment, the elastic deformability of the heat transfer plate52is improved by providing the slit54in the heat transfer plate52. Accordingly, since the heat transfer plate52supported by the heat sink support portion15in an elastically deformed state comes into close contact with the heat exhaust wall15bdue to the elastic return force, the heat exhaust efficiency is further improved. Further, the heat transfer plate52can elastically deform and absorb manufacturing errors or assembly errors of the heat sink support portion15, the heat sink50, and the cover60. A shape, position, number, and width of the slit54are appropriately selected depending on a material, thickness, or the like of the heat sink50. Further, the slit54can be omitted.

Further, according to the embodiment, it is possible to reduce a size of the heat sink50by providing the heat transfer plate52on the side closest to the circuit element23bthat generates a large amount of heat among the plurality of sides defining the outer edge of the control board20. As a result, since a heat transfer path from the circuit element23bto the heat sink support portion15is shortened, the heat exhaust efficiency is further improved. However, the disposition of the heat transfer plate52is not limited to the above-described example. As another example, a plurality of heat transfer plates52extending in different directions (for example, toward the left side and downward inFIG.2) from the heat reception plate51may be provided.

Furthermore, according to the embodiment, the heat exhaust efficiency is further improved by bringing the heat reception plate51into contact with the circuit element23bmounted on the second surface21bvia the heat dissipation agent55, compared to a board being interposed between the heat generation element and the heat sink as in Patent Document 1. However, a positional relationship between the circuit element23band the heat reception plate51is not limited to the above example.

The embodiments of the disclosure have been described above. The disclosure is not limited to the embodiments described above, and includes various modification examples. For example, the above-described embodiments have been described in detail to explain the disclosure in an easy-to-understand manner, and the disclosure is not necessarily limited to that including all the described configurations. Further, it is possible to replace a part of the configuration of the present embodiment with the configuration of other embodiments, and it is also possible to add the configuration of other embodiments to the configuration of the present embodiment. Furthermore, it is possible to perform addition, deletion, or replacement of other configurations with respect to some of the configurations of the present embodiment.