JP2014054017A - Vehicle motor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vehicle motor unit which reduces fastening points for attaching a heat radiation member to a circuit board and inhibits separation between the circuit board and a heat radiation material or separation between the heat radiation material and the heat radiation member.SOLUTION: A vehicle motor unit 10 includes: a motor 12; and a circuit board 18 to which multiple circuit elements 16 for controlling rotations of an output shaft 14 of the motor 12 are attached. A heat sink 20 is attached to the circuit board 18. Further, the heat sink 20 includes a pair of fastening parts 62. A line connecting the pair of fastening parts 62 with each other is disposed at an intermediate part of a portion where the circuit board 18 contacts with a facing surface 54 of the heat sink 20.

Description

  The present invention relates to a vehicle motor unit.

  In Patent Document 1 below, in order to cool a circuit element (MOS-FET) mounted on a circuit board, an aluminum plate is interposed between the circuit element and the heat dissipation container, A motor control unit (power module) in which a heat dissipation material (silicone grease) is interposed between the heat dissipation container and the heat dissipation container is disclosed. By interposing this heat dissipation material, the heat transmitted from the MOS-FET to the aluminum plate is easily transmitted to the heat dissipation container.

Japanese Patent Laid-Open No. 7-161925

  However, in a configuration in which the heat dissipation member is directly attached to the circuit board (attached without interposing an aluminum plate or the like), it is desirable to reduce the number of fastening points of the heat dissipation member to the circuit board in consideration of miniaturization of the circuit board. However, when the number of fastening points is reduced, it becomes difficult to press the heat radiating member evenly against the circuit board as the heat generation source. As a result, it is conceivable that the circuit board and the heat dissipation material are separated from each other, or the heat dissipation material and the heat dissipation member are separated from each other.

  In consideration of the above fact, the present invention can reduce the number of fastening points for attaching the heat dissipation member to the circuit board, and the circuit board and the heat dissipation material are separated from each other, or the heat dissipation material and the heat dissipation member are separated from each other. It is an object to obtain a vehicle motor unit that can be suppressed.

  According to a first aspect of the present invention, a motor unit for a vehicle according to the present invention is provided with a motor that rotates an output shaft about its axis when energized, and a plurality of circuit elements for controlling the rotation of the output shaft. A circuit board and a facing surface that is disposed on the circuit board on the side opposite to the mounting surface of the circuit element, and that is in contact with the circuit board via a heat dissipating material are provided at a portion facing the circuit element. A heat dissipating member having a pair of fastening portions arranged so as to sandwich the facing surface, and a line connecting the pair of fastening portions being disposed in an intermediate portion of the portion where the circuit board and the facing surface are in contact; It has.

  In the present invention, the rotation of the output shaft of the motor is controlled by the circuit element attached to the circuit board. Moreover, in this invention, the thermal radiation material is interposing between the circuit element and the opposing surface of a thermal radiation member. Therefore, the heat of the circuit element that generates heat by being energized is radiated through the heat radiating material and the heat radiating member. Furthermore, in the present invention, the heat dissipation member is attached to the circuit board via a pair of fastening portions arranged so as to sandwich the opposing surface, and a line connecting the pair of fastening portions is connected to the circuit board and the opposing surface. It is arrange | positioned in the intermediate part of the site | part which contacts. Therefore, it is suppressed that a heat radiating member inclines with respect to a circuit board by making the line which connects a pair of fastening part into an axial direction. As a result, the heat dissipation member can be evenly pressed against the circuit board. That is, in the present invention, the fastening points for attaching the heat dissipation member to the circuit board can be reduced, and the circuit board and the heat dissipation material are separated from each other, or the heat dissipation material and the heat dissipation member are prevented from being separated from each other. Can do. As a result, the contact thermal resistance between the circuit element and the heat dissipation member can be reduced.

  A vehicle motor unit according to a second aspect of the present invention is the vehicle motor unit according to the first aspect, wherein a direction in which a line connecting the pair of fastening portions extends is a longitudinal direction of the heat dissipation member.

  In the second aspect of the present invention, the heat dissipating member is attached to the circuit board via the pair of fastening portions, and the direction in which the line connecting the pair of fastening portions extends is the longitudinal direction of the heat dissipating member. Therefore, the intermediate portion in the longitudinal direction of the heat dissipation member can be evenly pressed against the circuit board. As a result, the heat dissipation efficiency can be improved.

  A vehicle motor unit according to a third aspect of the present invention is the vehicle motor unit according to the first or second aspect, wherein the heat dissipating material is in the form of a gel having thermal conductivity.

  In the third aspect of the present invention, since the heat dissipation material is in the form of a gel having thermal conductivity, the heat dissipation material is evenly interposed between the circuit board and the heat dissipation member. As a result, in the present invention, the contact thermal resistance between the circuit element and the heat dissipation member can be further reduced.

It is a disassembled perspective view which decomposes | disassembles and shows the motor unit for vehicles of this embodiment. (A) It is a perspective view which shows the circuit board to which the heat sink and the circuit element were attached, (B) is a side view of the circuit board shown to (A), (C) is from the opposite direction to (A). It is a perspective view which shows the circuit board which looked. It is the top view which looked at the circuit board from the opposite direction to the surface where the heat sink was attached. (A) is the top view which looked at the heat sink from the circuit board side, (B) is the expansion perspective view which expands and shows the edge part of the circuit board shown by (A).

  Next, the vehicle motor unit according to the embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the vehicle motor unit 10 of the present embodiment is a so-called blower motor unit used for blowing air from an in-vehicle air conditioner as an example. Specifically, the vehicle motor unit 10 includes a motor 12 that rotates an output shaft about its axis, a circuit board 18 on which a circuit element 16 for controlling the rotation of the output shaft 14 of the motor 12 is attached, And a heat sink 20 as a heat radiating member for radiating the heat of the circuit element 16. Hereinafter, the motor 12 will be described first, then the circuit board 18 will be described, and finally the heat sink 20 will be described.

(Motor 12)
The motor 12 includes an output shaft 14, a rotor 22, and a stator 24 as main elements.

  The output shaft 14 is configured by subjecting a cylindrical steel material to a surface treatment such as a carburizing treatment, and is rotatably supported by a bearing (not shown).

  The rotor 22 is formed in a bottomed cylindrical shape with one end open, a disc-shaped bottom wall 22A, and a peripheral wall 22B extending from the outer peripheral end of the bottom wall 22A to the one end side of the rotor 22, It has. Further, an insertion hole 22C into which the output shaft 14 is inserted is provided at the center of the bottom wall 22A, and the rotor 22 and the output shaft 14 are integrated by pressing the output shaft 14 into the insertion hole 22C. It can be rotated. A rotor magnet (not shown) is provided inside the peripheral wall 22B.

  The stator 24 is configured by winding a conductive winding 26 around a stator core 28 formed in an annular shape. Further, the stator 24 is disposed on the radially inner side of the peripheral wall 22B of the rotor 22, and the rotor 22 can rotate together with the output shaft 14 by receiving a magnetic field generated by the stator 24. More specifically, the stator 24 is an electromagnet in which a winding 26 is wound around a core member 30 that constitutes a stator core 28, and constitutes three phases of U phase, V phase, and W phase. Each of the U-phase, V-phase, and W-phase of the stator 24 generates a so-called rotating magnetic field by switching the polarity of the magnetic field generated by the electromagnet under the control of a motor drive control device 34 described later. The stator 24 is attached to the motor drive control device 34 via the upper case 32.

(Circuit board 18)
The circuit board 18 is formed in a rectangular plate shape, and constitutes a motor drive control device 34 together with the circuit element 16 and a heat sink 20 described in detail later. Specifically, as shown in FIG. 3, power supply terminals 36 </ b> A, 36 </ b> B, and 36 </ b> C that supply power to the U phase, V phase, and W phase of the stator 14 are provided near the center of the circuit board 18. It has been. In addition, a connector 38 to which a control device such as an ECU (Electronic Control Unit) is connected via a harness and a connector (not shown) is attached to the circuit board 18. Furthermore, a plurality of circuit elements 16 are attached to the circuit board 18. More specifically, capacitors 40A, 40B, 40C, and 40D are attached to the circuit board 18 in a state of being connected in parallel. Further, FETs 41A, 41B, 41C, 41D, 41E, and 41F are attached to the circuit board 18. The FETs 41A and 41D are configured to perform switching of the supplied power in the U phase, the FETs 41B and 41E in the V phase, and the FETs 41C and 41F in the W phase. Furthermore, a noise removing coil 44 is attached to the circuit board 18, and a reverse connection prevention FET 41G for protecting the circuit and a large-capacitance capacitor 42 are attached. Further, a microcomputer 46 for controlling the inverter circuit is attached to the circuit board 18. As shown in FIG. 1, the circuit board 18 is covered with a lower case 48.

(Heat sink 20)
In the circuit element 16 described above, the FETs 41A to 41F and the reverse connection prevention FET 41G generate significant heat during operation. Therefore, in the present embodiment, as shown in FIGS. 2A to 2C, the heat sink 20 is attached with circuit elements (FETs 41 </ b> A to 41 </ b> F and reverse connection prevention FETs 41 </ b> G) that generate significant heat during operation on the circuit board 18. It is attached via a fixing bolt 50 to a portion (surface opposite to the surface on which the FETs 41A to 41F and the reverse connection prevention FET 41G are attached) facing the portion in the plate thickness direction. Specifically, the heat sink 20 is made of a metal such as aluminum having good thermal conductivity, and is formed in a substantially rectangular plate shape when viewed from the thickness direction of the circuit board 18. In addition, a plurality of protrusions 52 are provided at one end in the short direction of the heat sink 20 along the longitudinal direction of the heat sink 20. The protrusions 52 protrude in a direction away from the circuit board 18. It is formed in a cylindrical shape. By having the plurality of protrusions 52, the surface area of the heat sink 20 is increased, and the heat dissipation performance of the heat sink 20 is improved.

  Further, as shown in FIGS. 2C, 4 </ b> A, and 4 </ b> B, a portion of the heat sink 20 that faces the circuit elements (the FETs 41 </ b> A to 41 </ b> F and the reverse connection prevention FET 41 </ b> G) is along the circuit board 18. An extending facing surface 54 is provided.

  Further, the heat sink 20 has a first leg portion 56 and a second leg portion 58 as legs that form a gap in which a heat dissipation material is interposed between the circuit board 18 and the facing surface 54 by contacting the circuit board 18. Is provided.

  The first leg portions 56 are provided at both ends in the longitudinal direction of the heat sink 20 and are formed in a rectangular shape with the short direction of the heat sink 20 as the longitudinal direction. Further, the first leg portion 56 protrudes toward the circuit board 18 from the above-described facing surface 54. Furthermore, the end surface in the protruding direction of the first leg portion 56 is an abutting surface 56 </ b> A that abuts on the circuit board 18.

  The second leg portions 58 are disposed at both end portions in the longitudinal direction of the heat sink 20 and corner portions on the other end side in the short direction of the heat sink 20. Further, the second leg portion 58 protrudes toward the circuit board 18 from the above-described facing surface 54. Further, the end surface in the protruding direction of the second leg portion 58 is a contact surface 58A that contacts the circuit board 18, and the contact surface 58A and the contact surface 56A of the first leg portion 56 are substantially plane. It is set to be one.

  In addition, a recess 60 that is recessed in a direction away from the circuit board 18 is provided in a portion adjacent to the facing surface 54. The recess 60 includes a first recess 60A disposed between the first leg 56 and the facing surface 54, a second recess 60B disposed between the second leg 58 and the facing surface 54, and a heat sink. And a third recess 60 </ b> C disposed along the outer peripheral edge of the 20.

  A portion of the first leg portion 56 on the other end side of the heat sink 20 is a fastening portion 62, and a screw hole 62 </ b> A into which the fixing bolt 50 is screwed is formed in the fastening portion 62. . The pair of fastening portions 62 are arranged so as to sandwich the facing surface 54, and a line L connecting the pair of fastening portions 62 (screw holes 62 </ b> A) contacts the circuit board 18 and the facing surface 54. It arrange | positions in the intermediate part of (the site | part enclosed with the dashed-two dotted line in FIG. 3). In other words, a portion where the circuit board 18 and the facing surface 54 are in contact with each other by a line L connecting the pair of fastening portions 62 (screw holes 62A) (a portion surrounded by a two-dot chain line in FIG. 3) is a short of the heat sink 20. It is the structure divided | segmented into the substantially bisection in the hand direction. In the present embodiment, the direction in which the line L connecting the pair of fastening portions 62 extends coincides with the longitudinal direction of the heat sink 20.

  The heat sink 20 is attached to the circuit board 18 via the fixing bolt 50 after the heat sink 20 (not shown) having a gel-like and thermal conductivity is applied to the facing surface 54 of the heat sink 20 described above. As a result, the facing surface 54 of the heat sink 20 and the circuit board 18 are in contact with each other through the heat dissipation material. Note that, as an example of the heat dissipation material, insulating silicon grease is used. However, a solid resin such as a silicone resin or a flexible rubber or resin that is hardened by heat generated by an element such as an FET at room temperature is used. The heat dissipation material can also be used.

(Operation and effect of this embodiment)
Next, the operation and effect of this embodiment will be described.

  As shown in FIG. 1, in the vehicle motor unit 10 of this embodiment, the rotation of the output shaft 14 of the motor 12 is controlled by a circuit element 16 attached to a circuit board 18. In the present embodiment, as shown in FIGS. 3 and 4, a heat dissipation material is interposed between the circuit elements (FETs 41 </ b> A to 41 </ b> F and the reverse connection prevention FET 41 </ b> G) and the facing surface 54 of the heat sink 20. Therefore, the heat of the circuit elements (FETs 41 </ b> A to 41 </ b> F and the reverse connection prevention FET 41 </ b> G) that generate heat by being energized is radiated through the heat dissipation material and the heat sink 20. Further, as shown in FIGS. 4A and 4B, in this embodiment, a recess 60 that is recessed in a direction away from the circuit board 18 is provided in a portion adjacent to the facing surface 54 of the heat sink 20. . Therefore, when the heat sink 20 is attached to the circuit board 18, the heat dissipating material protruding from between the facing surface 54 and the circuit element 16 is accommodated in the recess 60 (stays in the recess 60). As a result, in the present embodiment, it is possible to suppress the heat dissipation material from protruding between the heat sink 20 and the circuit board 18.

  In the present embodiment, the concave portion 60 includes the first concave portion 60 </ b> A provided between the first leg portion 56 and the facing surface 54 of the heat sink 20, and the second leg portion 58 and the facing surface 54 of the heat sink 20. And a second recess 60B provided between the two. Therefore, the heat dissipation material protruding from between the facing surface 54 and the circuit element 16 is interposed between the contact surface 56A of the first leg portion 56 and the contact surface 56B of the second leg portion 58 and the circuit board 18. Is suppressed. As a result, in the present embodiment, the heat sink 20 can be prevented from tilting with respect to the circuit board 18.

  Next, operations and effects unique to the present embodiment will be described.

  As shown in FIGS. 3 and 4, in the present embodiment, the heat sink 20 is attached to the circuit board 18 via a pair of fastening portions 62 arranged so as to sandwich the facing surface 54. A line L connecting the fastening portions 62 is disposed at an intermediate portion of the portion where the circuit board 18 and the facing surface 54 are in contact with each other. Therefore, the heat sink 20 is prevented from being inclined with respect to the circuit board 18 with the line L connecting the pair of fastening portions 62 as the axial direction. As a result, the heat sink 20 can be evenly pressed against the circuit board 18. That is, in the present embodiment, the fastening points for attaching the heat sink 20 to the circuit board 18 can be reduced, and the circuit board 18 and the heat dissipating material are separated or the heat dissipating material and the heat sink 20 are separated. Can be suppressed. As a result, the contact thermal resistance between the circuit element 16 and the heat sink 20 can be reduced. Note that the fact that the line L connecting the pair of fastening portions 62 is arranged in the middle portion of the portion where the circuit board 18 and the facing surface 54 are in contact does not mean a strict middle, and the above effect is obtained. It may deviate within a range.

  In the present embodiment, the heat sink 20 is attached to the circuit board 18 via the pair of fastening portions 62, and the direction in which the line L connecting the pair of fastening portions 62 extends coincides with the longitudinal direction of the heat sink 20. Yes. Therefore, the intermediate portion in the longitudinal direction of the heat sink 20 can be evenly pressed against the circuit board 18. As a result, in this embodiment, the heat dissipation efficiency can be improved.

  Furthermore, in this embodiment, since the heat radiating material is in a gel form having thermal conductivity, the heat radiating material is evenly interposed between the circuit board 18 and the heat sink 20. As a result, in this embodiment, the contact thermal resistance between the circuit element 16 and the heat sink 20 can be further reduced.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and various modifications other than the above can be implemented without departing from the spirit of the present invention. Of course.

DESCRIPTION OF SYMBOLS 10 ... Motor unit for vehicles, 12 ... Motor, 14 ... Output shaft, 16 ... Circuit element, 18 ... Circuit board, 20 ... Heat sink (heat dissipation member), 41A-41G ..FET (circuit elements), 62 ... fastening part

Claims (3)

A motor that rotates the output shaft around its axis when energized;
A circuit board on which a plurality of circuit elements for controlling the rotation of the output shaft are mounted;
In the circuit board, a facing surface that is disposed on the opposite side of the mounting surface of the circuit element and that faces the circuit element is provided to contact the circuit board via a heat dissipation material, and the facing surface is A heat dissipating member having a pair of fastening portions arranged so as to be sandwiched, and a line connecting the pair of fastening portions being arranged at an intermediate portion of the portion where the circuit board and the facing surface are in contact;
A motor unit for vehicles comprising   The vehicle motor unit according to claim 1, wherein a direction in which a line connecting the pair of fastening portions extends is a longitudinal direction of the heat dissipation member.   The motor unit for vehicles according to claim 1 or 2 in which said heat dissipation material is made into the gel form which has heat conductivity.

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