JP6049584B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor equipped with a power board through which a large current is passed.

  Conventionally, as a heat dissipation measure for a power board equipped with a power element that is energized with a large current, the power element mounted on the power board surface is exposed to a heat sink on the back side of the power board through a through hole provided in the power board. (For example, refer to Patent Document 1). In addition, there is a method in which a large number of through holes having a small diameter (about φ0.2 mm to φ0.8 mm) are provided directly below or around the power element of the power substrate, and heat is radiated to the heat sink via the through hole. In these methods, it is necessary to increase the diameter of the through holes or increase the number of through holes in order to increase the heat dissipation efficiency. As a result, the substrate area is increased, and the product value is lowered.

  Moreover, in the said patent document 1, the high heat dissipation of the board | substrate material was implemented as a heat dissipation countermeasure of a power board. A substrate having a high diffusion rate, high versatility, and low cost is a resin substrate (glass epoxy substrate). However, in Patent Document 1, the power substrate material is changed to ceramic or aluminum, so that It was possible to dissipate heat efficiently. However, increasing the heat dissipation of the substrate material causes an increase in substrate cost (about 5 times in the same volume ratio).

JP-A-5-167005

  As described above, the conventional heat radiation countermeasure has problems that the product value decreases and the cost increases in exchange for the efficiency of heat radiation, and thus further improvement has been desired.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an electric motor capable of efficiently dissipating heat of a power element.

An electric motor according to the present invention is an electric motor including a board on which a power element is mounted and a housing to which a surface opposite to the power element mounting surface of the board is fixed, and the board is opened immediately below the power element. has a through hole, the housing, is inserted into the through-hole, via the radiation material have a convex portion which is joined to the back of the power device, the heat radiating member, between the back surface and the convex portion of the power element The space between the through hole and the convex portion and between the surface of the substrate opposite to the mounting surface of the power element and the housing is filled without interruption .

According to this invention, the convex portion of the housing is inserted into the through hole of the substrate and joined to the back surface of the power element through the heat dissipation material , and the heat dissipation material is interposed between the back surface and the convex portion of the power element, Since the space between the through hole and the convex part and between the surface of the substrate opposite to the mounting surface of the power element and the housing is filled without interruption , the heat generated by the power element is radiated from the heat dissipation material and the housing. The heat can be efficiently radiated to the outside of the housing via the convex portion.

It is sectional drawing which shows the structure of the electric motor which concerns on Embodiment 1 of this invention. It is the figure which expanded the peripheral structure of the power element shown in FIG. It is sectional drawing which shows the modification of the electric motor which concerns on Embodiment 1, and is the example which provided the radiation fin. It is sectional drawing which shows the modification of the electric motor which concerns on Embodiment 1, and is the example which provided the water cooling channel | path. It is sectional drawing which shows the modification of the electric motor which concerns on Embodiment 1, and is the example which comprised the heat transfer path | route in the cover side.

Embodiment 1 FIG.
An electric motor 1 shown in FIG. 1 includes an electric motor main body 10, a control unit 20 that controls driving of the electric motor main body 10, a housing 30 that houses the electric motor main body 10 and the control unit 20, and a cover 40 that covers the control unit 20. With.

The housing 30 is made of metal, and it is particularly desirable to use aluminum having high thermal conductivity. A partition wall 31 is formed inside the cylindrical housing 30. The electric motor main body 10 is accommodated on one side partitioned by the partition wall 31, and the control unit 20 is accommodated on the other side. Further, a convex portion 32 to be inserted into the through hole 21 a of the power substrate 21 is formed on the surface of the partition wall 31 on the side where the control unit 20 is accommodated.
The other cover 40 may be configured using, for example, a high heat dissipation resin.

The control unit 20 includes a power board 21 on which a power element 22 (for example, MOSFET) is mounted, and a control board 23 on which a rotation sensor 24 is mounted. The power board 21 and the control board 23 are configured by adopting an inexpensive resin board such as a glass epoxy board, and are installed on the partition wall 31 of the housing 30.
In the example of FIG. 1, the power board 21 and the control board 23 are separate boards and are electrically connected by the connection 26, but the power board 21 and the control board 23 may be a single board.

FIG. 2 is an enlarged view of the peripheral structure of the power element 22.
The power board 21 has a through hole 21a that opens directly below the power element 22 that is a heat generating element, and the convex portion 32 of the partition wall 31 is inserted into the through hole 21a. Bonded to the back of the. As the heat dissipation material 33, a sheet-like member or grease made of a material having high thermal conductivity is used. The heat generated by the power element 22 is radiated from the cylindrical portion of the housing 30 to the outside via the heat radiating member 33, the convex portion 32 of the housing 30, and the partition wall 31 (heat transfer path H shown in FIG. 1).

Here, the dimensional relationship of the peripheral structure of the power element 22 will be described.
In FIG. 2, the thickness A1 of the heat dissipation material 33 filled between the partition wall 31 and the power substrate 21, the thickness A2 of the heat dissipation material 33 filled between the convex portion 32 and the back of the power element 22, the power substrate 21. Thickness B, height C of the protrusion 32 protruding from the partition wall 31, and height D from the partition wall 31 to the back of the power element 22.
The height C of the convex portion 32 protruding from the partition wall 31 is set to such a height as to protrude from the through hole 21a of the power substrate 21, that is, the dimensional relationship of the following expression (1).
A1 + B <C (1)
Further, the radiating material 33 is surely in contact with the back surface of the power element 22 and the convex portion 32 is in a dimensional relationship that does not contact the back surface of the power element 22, that is, a dimensional relationship of the following expression (2).
D <C + A2 and C <D (2)

  By setting the peripheral structure of the power element 22 to the dimensional relationship of the formulas (1) and (2), the power element 22 and the heat radiating material 33 are surely brought into contact with each other to ensure the heat transfer path H (FIG. 1). Moreover, since the convex part 32 of the housing 30 comprises the heat transfer path | route H, heat dissipation efficiency improves.

  In order to further improve the heat dissipation efficiency, the heat dissipation material 33 is interrupted in the gap between the convex portion 32 and the power element 22, the gap between the convex portion 32 and the through hole 21 a, and the gap between the partition wall 31 and the power substrate 21. It is desirable that it is continuously filled.

  In order to further improve the heat dissipation efficiency, it is desirable that the copper pattern 21b is exposed on the surface of the power substrate 21 on the partition wall 31 side, and the copper pattern 21b is directly in contact with the heat dissipation material 33. However, since the housing 30 may be energized by the direct contact between the copper pattern 21 b and the heat dissipation material 33, it is necessary to use a material having electrical insulation as the heat dissipation material 33.

In the control unit 20, for example, a rotation sensor 24 that detects the rotation position of the shaft 11 is mounted on the control board 23. A sensor target 25 is fixed to the tip of the shaft 11, and the shaft 11 and the sensor target 25 rotate together.
The rotation sensor 24 includes, for example, a sensor magnet (not shown) that generates a magnetic field that passes through a magnetic sensor target 25 and a Hall element or magnetoresistor that detects the magnetic flux of the sensor magnet that changes according to the rotational position of the sensor target 25. And a sensor element (not shown) such as an element. Alternatively, the sensor target 25 may be configured by a magnet, and the rotation sensor 24 may include a sensor element (not shown) that detects a magnetic flux that changes according to the rotational position of the sensor target 25.

Next, the electric motor main body 10 will be described. The following electric motor main body 10 is an example, and is not limited to this configuration.
The electric motor body 10 is wound with a shaft 11 housed in a housing 30, a bearing 12 that rotatably supports the shaft 11, a rotor 13 that rotates integrally with the shaft 11, and a coil (not shown). Energize the stators 14 and 15 that generate a rotating magnetic field by energization, the field magnet 16 that is installed between the stators 14 and 15 to magnetize the rotor 13, and the coils wound around the stators 14 and 15. And a bus bar 17.

  The magnetic stators 14 and 15 are formed with a plurality of teeth protruding inward in the circumferential direction, and a coil (not shown) is wound in the rotation axis direction X. A field magnet 16 is installed between the stators 14 and 15. The magnetic rotor 13 is formed with two protrusions protruding radially outward at intervals of 180 degrees, and the protrusions are shifted 90 degrees in the middle of the rotation axis direction X (protrusions 13a and 13b). . These protrusions 13 a and 13 b are magnetized by the action of the field magnetic force of the field magnet 16.

  When power is supplied from an external power source (not shown) to the control unit 20, the control board 23 outputs a control signal for controlling the switching operation of the power element 22 based on the rotational position of the shaft 11 detected by the rotation sensor 24. To do. This control signal is input to the power board 21 through the connection 26, and the power element 22 performs a switching operation according to the control signal to convert the external power source into, for example, a U-phase, V-phase, and W-phase three-phase alternating current. The molded three-phase coil 17a is supplied. Then, teeth of the stators 14 and 15 are magnetized according to the direction of the current flowing through the coil 17a, and a rotating magnetic field is generated around the rotor 13 where the field magnetic force of the field magnet 16 acts. The rotor 13 is driven to rotate.

  By fixing the shaft 11 to the rotor 13 and rotating the shaft 11 integrally with the rotor 13, the rotational force generated in the rotor 13 is externally output. When the electric motor 1 is applied to an automobile turbocharger, an electric compressor, and the like, the shaft 11 is connected to a rotating shaft of a turbine (so-called impeller), and the electric motor 1 rotates the turbine.

  As described above, according to the first embodiment, in the electric motor 1 including the power board 21 on which the power element 22 is mounted and the housing 30 on which the surface opposite to the power element 22 mounting surface of the power board 21 is fixed. The power board 21 has a through hole 21a opened immediately below the power element 22, and the housing 30 is inserted into the through hole 21a and joined to the back surface of the power element 22 via the heat dissipation material 33. Therefore, the heat of the power element 22 can be efficiently radiated to the outside of the housing 30 via the heat radiating member 33 and the convex portion 32. As a result, it is not necessary to increase the diameter of the through-hole of the substrate or increase the number of through-holes as in the prior art, and it is possible to prevent the substrate area from being expanded and the product value from being lowered. Moreover, it is not necessary to use a high heat dissipation ceramic or aluminum as a material for the power substrate, and an inexpensive resin substrate can be used.

  Further, according to the first embodiment, the heat radiating material 33 is disposed between the back surface of the power element 22 and the convex portion 32, between the through hole 21 a and the convex portion 32, and the power element 22 mounting surface of the power substrate 21. Was filled between the opposite surface and the housing 30 (partition wall 31) without interruption. For this reason, it can thermally radiate efficiently.

  Further, according to the first embodiment, the height C of the convex portion 32 protruding from the housing 30 (partition wall 31) is higher than the total thickness A1 or A2 of the heat dissipation material 33 and the thickness B of the power board 21. The height is higher than the height D from the housing 30 (partition wall 31) to the back of the power element 22. For this reason, the back surface of the power element 22 can be surely brought into contact with the heat radiating material 33 and efficiently radiated.

  Further, according to the first embodiment, as the power substrate 21, a resin substrate having a copper pattern 21 b provided on the surface opposite to the mounting surface of the power element 22 is used, and the copper pattern 21 b is directly attached to the heat dissipation material 33. I made contact. For this reason, it can thermally radiate efficiently.

  Moreover, according to Embodiment 1, since the housing 30 was comprised with aluminum with high heat conductivity, it can thermally radiate efficiently.

Furthermore, it is possible to improve the heat dissipation efficiency by providing the housing 30 with a heat dissipation structure.
For example, in the example of FIG. 3, the radiation fins 50 are provided on the outer peripheral portion of the housing 30, and the heat of the power element 22 is efficiently radiated from the housing 30 to the outside via the radiation fins 50.
Further, for example, in the example of FIG. 4, the water cooling passage 51 is provided in the housing 30 and the partition wall 31, and the cooling water is caused to flow through the water cooling passage 51 through the nipple 52. The heat of the power element 22 is efficiently transferred to the water cooling passage 51 through the heat radiating member 33 and the convex portion 32, and absorbed by the cooling water.

  1 to 4, the power board 21 is fixed to the partition wall 31 of the housing 30, but the power board 21 may be fixed to the cover 40 as shown in FIG. 5, for example. In this case, the cover 40 is made of aluminum having a high thermal conductivity, and a protrusion 41 for projecting into the through hole 21 a of the power substrate 21 is provided on the cover 40. Thereby, the heat generated by the power element 22 is efficiently radiated from the cover 40 to the outside via the heat radiation member 33 and the convex portion 41 (heat transfer path H shown in FIG. 5).

  In addition to the above, within the scope of the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted.

  DESCRIPTION OF SYMBOLS 1 Electric motor, 10 Electric motor main body, 11 Shaft, 12 Bearing, 13 Rotor, 14, 15 Stator, 16 Field magnet, 17 Bus bar, 17a Coil, 20 Control part, 21 Power board, 21a Through hole, 21b Copper pattern, 22 power element, 23 control board, 24 rotation sensor, 25 sensor target, 26 connection, 30 housing, 31 partition wall, 32, 41 convex part, 33 heat radiation material, 40 cover, 50 heat radiation fin, 51 water cooling passage, 52 nipple.

Claims (7)

In an electric motor comprising a substrate on which a power element is mounted and a housing on which a surface opposite to the mounting surface of the power element of the substrate is fixed.
The substrate has a through hole opened directly under the power element,
Said housing, said plugged into the through-hole, via the radiation material have a convex portion joined to the back of the power element,
The heat dissipating material is between the back surface of the power element and the convex part, between the through hole and the convex part, and between the surface of the substrate opposite to the mounting surface of the power element and the housing. In addition, the electric motor is filled without interruption . The height of the convex portion protruding from the housing is higher than the total of the thickness of the heat dissipation material and the thickness of the substrate, and lower than the height from the housing to the back surface of the power element. The electric motor according to claim 1 . The said board | substrate is a resin substrate by which the copper pattern was provided in the surface opposite to the mounting surface of the said power element, The said copper pattern is directly contacting the said heat radiating material, or characterized by the above-mentioned. The electric motor according to claim 2 . The electric motor according to claim 3 , wherein the heat dissipating material has electrical insulation. The electric motor according to any one of claims 1 to 4 , wherein the housing is made of aluminum. The electric motor according to claim 1, wherein the housing has a heat dissipation structure. The electric motor according to claim 6 , wherein the heat dissipation structure is a heat dissipation fin provided on an outer peripheral portion of the housing.

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