JP2015096010A - Electronic unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat radiation performance.SOLUTION: An electronic unit 10 includes: a circuit board 11 having a conductive path; an electronic component 16 mounted on the circuit board 11; a heat radiation member 35 having a plate-like part 36 overlapped with the circuit board 11 and multiple heat radiation fins 39 disposed arranged in a direction perpendicular to a plate surface of the plate-like part 36; and a fan 28 which blows air to multiple opening parts 40 located between the adjacent heat radiation fins 39. At least one of the multiple opening parts 40 is formed as a small opening part 42 having an opening area smaller than those of the other opening parts 40.

Description

  The present invention relates to an electronic unit.

2. Description of the Related Art Conventionally, an electronic unit that radiates heat of a circuit board to the outside via a heat radiating member is known.
Patent Document 1 describes a vehicle power distributor in which an FET is connected to a heat dissipation member via a conductive plate. In Patent Document 1, a plurality of FETs are arranged side by side on one surface side of a heat radiating member, and heat of the FET and the conductive plate is radiated to the outside from a fin provided on the side opposite to the one surface. It is like that.

JP 2002-315148 A

  By the way, in the structure of patent document 1, although the heat | fever transmitted to the heat radiating member is dissipated to the air between fins, since the air between fins does not move, the heat of the air between fins cannot escape easily outside, and heat dissipation. It was an obstacle to increase.

  The present invention has been completed based on the above circumstances, and an object thereof is to improve heat dissipation.

  The electronic unit of the present invention is arranged in a direction crossing a circuit board having a conductive path, an electronic component mounted on the circuit board, a plate-like portion overlaid on the circuit board, and a plate surface of the plate-like portion. A heat dissipating member having a plurality of heat dissipating fins, and a blowing means for blowing air to a plurality of openings between the adjacent heat dissipating fins, and at least one of the plurality of openings includes another opening. The opening area is smaller than the opening portion.

If it does in this way, air will distribute | circulate the inside of the opening part between radiation fins by ventilating by a ventilation means, and heat dissipation can be improved.
Here, among the air blown by the blowing means, the air blown to the small opening can make the flow rate faster than the other openings in the small opening having a small opening area. Even if the temperature becomes partially high, it becomes possible to radiate the heat of the high temperature portion through the small opening, and the heat dissipation can be further improved.

In addition to the above configuration, the following configuration is preferable.
-The plate-like portion is formed with a thick-walled portion that reduces the opening area of the small opening by making the plate-like portion thick.
In this way, if the plate-like portion is thickened by the thick-walled portion, the heat capacity of that portion can be increased, so that an increase in temperature when the output is momentarily increased can be suppressed.

The small opening is formed at a position near the electronic component.
In this way, the heat of the electronic component can be effectively radiated and the temperature rise of the electronic component can be suppressed.

A plurality of the electronic components are provided, and the plurality of electronic components includes a low heat generation component and a high heat generation component that generates heat more than the low heat generation component; It is formed at a position close to high heat-generating parts.
In this way, the heat of the high heat-generating component can be dissipated through the small opening, and therefore, the heat at the part that is locally high in temperature can be efficiently dissipated.

The electronic component is a plurality of SMD coils that are selectively energized, and the plurality of SMD coils that are selectively energized are mounted at positions separated from each other on the circuit board.
In this way, since the heat of the SMD coil can be dispersed on the circuit board, it is possible to prevent the circuit board from being locally heated.

-The fin cover which closes the front end side of the said heat radiating fin is mounted | worn with the said heat radiating member.

  According to the present invention, heat dissipation can be improved.

Plan view showing the electronic unit Front view showing the electronic unit Exploded perspective view of circuit board, holding member, fan, heat dissipation member and fin cover A plan view of a state in which a circuit board, a holding member, a fan, a heat dissipation member, and a fin cover are assembled. AA sectional view of FIG. BB sectional view of FIG. Top view showing heat dissipation member Front view showing heat dissipation member

<Embodiment>
The embodiment will be described with reference to FIGS. 1 to 8.
The electronic unit 10 (FIG. 1) is mounted on a path from a battery (power source) to a load in a vehicle (not shown) such as an electric vehicle or a hybrid vehicle. This embodiment is applied to a DC-DC converter as one form of an electronic unit. In the following, the vertical direction will be described with reference to the direction of FIG. 2, and the vertical direction will be described with the lower side of FIG.

(Electronic unit 10)
As shown in FIGS. 3 and 4, the electronic unit 10 is superimposed on the circuit board 11 having a conductive path, the electronic component 16 mounted on the circuit board 11, and the circuit board 11. , A holding member 20 that holds the circuit board 11 and the heat radiating member 35 in a positioned state, and a fan 28 (an example of a “blower unit”) that blows air to the heat radiating member 35.

(Circuit board 11)
The circuit board 11 has a rectangular shape, and a printed circuit board 12 in which a conductive path made of copper foil or the like is printed on an insulating plate made of an insulating material, and a metal plate material such as copper or copper alloy in the shape of the conductive path. A bus bar 13 formed by punching is laminated and bonded together.

  The bus bar 13 is bent at the peripheral edge of the circuit board 11 to form a plurality of terminals 14A, 14B, and 14C. The terminal 14A is a terminal connected to the outside. The terminal 14A is inserted into the rubber plug 15 and the rubber plug 15 is fitted into the holding member 20 so that the terminal 14A is positioned. Further, a heat radiating member fixing portion 14D is formed integrally with the middle terminal 14A, and this heat radiating member fixing portion 14D is screwed to the upper surface of the heat radiating member 35.

(Electronic component 16)
The electronic component 16 includes a MOSFET, a capacitor 16E, and SMD (Surface Mount Device) coils 16A to 16D. The SMD coils 16A to 16D are small-sized power inductors mounted on the surface of the circuit board 11, have a rectangular parallelepiped shape, have terminals on the bottom surface, and, for example, wrap a copper wire around a ferrite drum core, It can be covered. The SMD coils 16 </ b> A to 16 </ b> D are high heat generation components that generate heat more than the electronic component 16 such as the capacitor 16 </ b> E when energized, and the electronic components 16 such as the capacitor 16 </ b> E are low heat generation components.

The SMD coils 16 </ b> A and 16 </ b> B and the SMD coils 16 </ b> C and 16 </ b> D are mounted in pairs at diagonal positions on the circuit board 11.
In this way, the SMD coils 16A to 16D arranged at the most spaced positions on the circuit board 11 are selectively energized during the operation of the DC-DC converter. Specifically, one of the SMD coils 16A and 16B is energized when the voltage is increased, and the other SMD coils 16C and 16D are energized when the voltage is decreased. Thus, by separating the positions of the SMD coils 16A and 16B and the SMD coils 16C and 16D that are selectively energized, the heat generated by the energization of the SMD coils 16A to 16D can be dispersed. Can be prevented from becoming too hot.

  Note that another circuit board (not shown) is opposed to the circuit board 11 with a space therebetween, and the conductive path of the other circuit board is connected to the terminal 14B. The other circuit board is covered with a metal shield case (not shown) together with the circuit board 11. As shown in FIG. 1, the shield case is covered with a rectangular upper cover 19. The upper cover 19 is provided with a breathable waterproof valve 34 for adjusting the internal pressure.

(Holding member 20)
The holding member 20 is made of synthetic resin, and includes a rectangular frame portion 21 and a fan fixing portion 24 that fixes a pair of left and right fans 28 as shown in FIGS. 3 and 4. The frame portion 21 has an inner periphery along the outer periphery of the circuit board 11, and a portion where the choke coil 18 is disposed is partitioned. A terminal fixing portion 22 to which the terminal 14 </ b> C is fixed by screwing is formed on the upper surface inside the frame portion 21. A terminal support portion 23 that supports the terminal 14 </ b> A from below is formed on the outside of the frame portion 21.

The fan fixing portion 24 is formed integrally with the front end portion of the frame portion 21, and a pair of rectangular fan mounting holes 25 into which the fan 28 is fitted are formed. A fastening portion 26 having a screw hole for screwing the fan 28 is formed on the back side of the fan mounting hole 25. The left and right fan fixing portions 24 are separated from each other with the partition wall 27 interposed therebetween.
A groove (not shown) into which a sealing member (not shown) is poured is formed on the heat radiating member 35 side of the holding member 20, and the holding member 20 and the heat radiating member 35 are in close contact with each other via the sealing member.

(Fan 28)
A pair of left and right fans 28 are provided, and each fan 28 blows substantially half of the heat radiating member 35. As shown in FIGS. 2 and 3, a fan main body 29 that rotates to blow air and a fan main body 29 is provided.

  The fan case 30 has a slightly flat rectangular shape, and includes a fan support portion 31 that pivotally supports the fan body 29 from the front side so as to be connected to the inside of the rectangular outer frame, and has a circular shape that communicates the front and rear spaces. Ventilation opening 32 is formed. The ventilation opening 32 opens with a diameter slightly larger than the outer diameter of the fan main body 29. Further, the fan case 30 is provided with fastening portions 33 having screw holes for screwing to the fastening portions 26 of the holding member 20 at the positions of the four corners.

(Heat dissipation member 35)
The heat dissipating member 35 is made of a metal material having high thermal conductivity such as an aluminum alloy or a copper alloy, and as shown in FIGS. 7 and 8, a plate-like portion 36 overlaid on the circuit board 11 and a plate surface of the plate-like portion 36. And a plurality of heat dissipating fins 39 arranged in a comb-blade shape in the direction intersecting with each other, and the whole is integrally formed by extrusion molding, thereby having a cross section of the same shape over the entire length in the front-rear direction. doing. Each radiating fin 39 extends downward at equal intervals in the left-right direction on the bottom surface of the plate-like portion 36, and the position of the lower end of each radiating fin 39 is equal.

  The upper surface of the plate-like portion 36 is formed flat over the entire surface, and the circuit board 11 is placed and attached to the circuit board 11 with an insulating heat conductive adhesive. A plurality of screw holes 36 </ b> A for fixing the circuit board 11 and the holding member 20 are formed on the upper surface of the plate-like portion 36.

Here, as shown in FIGS. 5 and 6, the plate-like portion 36 has different thicknesses (A1, A2) depending on the position in the left-right direction. Specifically, the plate-like portion 36 includes a constant diameter portion 37 having a normal constant thickness dimension A 1 and a thick portion 38 having a thickness dimension A 2 that is thicker than the constant diameter portion 37. By forming the thick portion 38 in this way, the opening portion 40 formed by being partitioned by the plate-like portion 36 and the adjacent radiating fins 39 (and the fin cover 43) is provided at the position of the constant diameter portion 37. A constant opening 41 having a normal opening area and a small opening 42 provided at a position of the thick portion 38 and having an opening area smaller than that of the constant opening 41.
The positions of the thick wall portion 38 and the small opening portion 42 are formed at positions close to the SMD coils 16A to 16D, which are high heat generating components. In this embodiment, the thick part 38 and the small opening part 42 are formed under the SMD coils 16A to 16D.
As a result, the heat of the SMD coils 16A to 16D is transmitted to the thick portion 38, and the air that has passed through the ventilation port 32 by the air blown by the fan 28 flows into the opening 40, but the constant opening 41 having a normal size. Since the opening area of the small opening portion 42 is smaller than that of the small opening portion 42, the air flow in the small opening portion 42 is larger than that of the constant opening portion 41, and the heat from the thick wall portion 38 is efficiently transferred from the small opening portion 42 to the outside. I can escape.

  A plate-like fin cover 43 is attached under the heat radiating member 35. As shown in FIG. 3, the fin cover 43 is attached to the side surface of the heat radiating member 35, with a flat plate-like closing portion 44 that closes the opening of the heat radiating member 35 from below, and both ends of the closing portion 44 bent upward. The closing part 44 and the attaching part 46 are integrally formed. The closing portion 44 is formed with a plurality of concave portions 45 arranged in a staggered manner. The closing part 44 closes the opened part between the radiation fins 39, thereby forming a cylindrical air flow path.

According to the present embodiment, the following operations and effects are achieved.
The electronic unit 10 includes a circuit board 11 having a conductive path, an electronic component 16 mounted on the circuit board 11, a plate-like portion 36 superimposed on the circuit board 11, and a direction intersecting the plate surface of the plate-like portion 36. A heat dissipating member 35 having a plurality of heat dissipating fins 39 arranged side by side; and a fan 28 (air blowing means) for blowing air to a plurality of openings 40 between adjacent heat dissipating fins 39. At least one of them is a small opening 42 having an opening area smaller than that of the other opening 40.

If it does in this way, air will distribute | circulate the inside of the opening part 40 between the radiation fins 39 by blowing with the fan 28, and can improve heat dissipation.
Here, among the air blown by the fan 28, the air blown to the small opening 42 can make the flow velocity faster than the other openings 40 in the small opening 42 having a small opening area. Even if the circuit board 11 is partially heated, the heat of the high temperature portion can be released to the outside through the small openings 42, and the heat dissipation can be further improved.

Further, the plate-like portion 36 is formed with a thick-wall portion 38 that reduces the opening area of the small opening portion 42 by making the plate-like portion 36 thick.
In this way, if the plate-like portion 36 is thickened by the thick portion 38, the heat capacity of that portion can be increased, so that an increase in temperature when the output is momentarily increased can be suppressed.

Further, the small opening 42 is formed at a position near the electronic component 16.
In this way, the heat of the electronic component 16 can be effectively radiated by the small openings 42 and the temperature rise of the electronic component 16 can be suppressed.

A plurality of electronic components 16 are provided, and the plurality of electronic components 16 includes a capacitor 16E (low heat generation component) and SMD coils 16A to 16D (high heat generation components) that generate heat from the capacitor 16E. 42 is formed at a position closer to the SMD coils 16A to 16D than the capacitor 16E.
In this way, since the heat of 16A to 16D can be radiated by the small openings 42, the heat of the portion that is locally high in temperature can be efficiently radiated.

Further, the electronic component 16 is a plurality of SMD coils 16A to 16D that are selectively energized, and the plurality of SMD coils 16A to 16D that are selectively energized are mounted on the circuit board 11 at positions separated from each other. Yes.
In this way, since the heat of the SMD coils 16A to 16D can be dispersed on the circuit board 11, it is possible to suppress the circuit board 11 from being locally heated.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above embodiment, the small opening portion 42 is formed by providing the thick portion 38 in the heat radiating member 35. However, the present invention is not limited to this, and the small opening portion 42 is formed without providing the thick portion 38. Also good.
(2) In the above embodiment, the air blowing means is the fan 28, but air blowing means other than the fan 28 may be used to blow air to the opening 40.
(3) The positions and numbers of the small openings 42 and the thick portions 38 are not limited to the positions and numbers in the above-described embodiment, and the small openings 42 and the thick portions 38 may be formed at different positions and numbers.

10: Electronic unit 11: Circuit board 16: Electronic components 16A to 16D: SMD coil (high heat generation component)
16E: Capacitor (low heat generation component)
20: Holding member 28: Fan 35: Heat radiating member 36: Plate-shaped portion 37: Constant diameter portion 38: Thick portion 39: Radiating fin 40: Opening portion 41: Constant opening portion 42: Small opening portion 43: Fin cover

Claims (6)

A circuit board having a conductive path;
Electronic components mounted on the circuit board;
A heat dissipating member having a plate-like portion overlaid on the circuit board and a plurality of heat dissipating fins arranged in a direction intersecting with the plate surface of the plate-like portion;
Air blowing means for blowing air to a plurality of openings between the adjacent heat dissipating fins,
An electronic unit in which at least one of the plurality of openings is a small opening having a smaller opening area than the other openings. The electronic unit according to claim 1, wherein the plate-like portion is formed with a thick-wall portion that reduces the opening area of the small opening portion by making the plate-like portion thick. The electronic unit according to claim 1, wherein the small opening is formed at a position near the electronic component. A plurality of the electronic components are provided, and the plurality of electronic components includes a low heat generation component and a high heat generation component that generates heat more than the low heat generation component,
4. The electronic unit according to claim 1, wherein the small opening is formed at a position closer to the high heat generation component than the low heat generation component. 5. The electronic component is a plurality of SMD coils that are selectively energized, and the plurality of SMD coils that are selectively energized are mounted at positions separated from each other on the circuit board. 5. The electronic unit according to any one of 4. The electronic unit according to claim 1, wherein a fin cover that closes a front end side of the heat radiating fin is attached to the heat radiating member.

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