JP2011049312A - Heat radiation structure of electronic control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiation structure of an electronic control unit that efficiently accelerates heat radiation even when the heating value of a heating component increases. <P>SOLUTION: In the electronic control unit 1 having a circuit board 10, mounted with electronic components 12A and 12B including the heating component, incorporated in a sealed housing 5 comprising an upper case 20 and a lower case 30 in a state wherein an upper surface is covered with an upper surface plate 21 of the upper case and a lower surface is covered with a lower surface plate 31 of the lower case such that one side of the heating component in a plane along the circuit board is a high-temperature side H and a side apart from the heating component is a low-temperature side C, a step or gradient is provided to the upper surface plate of the upper case so that a height h3 of a space 40C from the circuit board on the low-temperature side to the upper surface plate of the upper case is larger than a height h1 of a space 40A from the circuit board on the high-temperature side to the upper surface plate of the upper case. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a heat dissipation structure for an electronic control unit mounted on, for example, an automobile.

  For example, Patent Document 1 discloses a case in which a heat radiating hole is opened in a housing that accommodates a circuit board therein. However, if the heat radiating hole is opened, the sealing performance of the housing is impaired, so There was a problem that the performance decreased.

JP 2002-26556 A

  In the case of the above-mentioned Patent Document 1, there is a problem that when the amount of heat generated by the heat-generating component on the circuit board increases, the heat dissipation is likely to deteriorate.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat dissipation structure for an electronic control unit that can efficiently promote heat dissipation even when the heat generation amount of a heat generating component increases.

  The present invention provides a heat generating component in a state where an upper surface is covered with an upper surface plate of the upper case and a lower surface is covered with a lower surface plate of the lower case, inside a sealed casing composed of an upper case and a lower case. In an electronic control unit in which a circuit board on which an electronic component is mounted is mounted, a side having the heat generating component in a plane along the circuit board is a high temperature side, and a side away from the heat generating component is a low temperature side, The height of the space from the circuit board to the upper surface plate of the upper case on the low temperature side is larger than the height of the space from the circuit board to the upper surface plate of the upper case on the high temperature side. The upper surface plate of the upper case is provided with a step or a gradient.

  According to the present invention, since the height of the space on the low temperature side is larger than the height of the space on the high temperature side inside the housing, convection can be caused in the space between the circuit board and the upper case, The heat generated from the heat generating component can be efficiently guided to the low temperature side to be dissipated, and the cooling efficiency can be increased.

It is a disassembled perspective view of embodiment of this invention. It is the disassembled perspective view seen from the direction different from FIG. 1 of the embodiment. It is a perspective view which shows the structure by the side of the inner surface of the upper case in the same embodiment. It is a perspective view which shows the assembly state of the embodiment. 4A is a cross-sectional view taken along the line AA in FIG. 4, FIG. 4B is a schematic explanatory diagram illustrating a flow of first air that occurs inside the housing, and FIG. 4C is a diagram illustrating the second air that occurs inside the housing. It is a schematic explanatory drawing which shows a flow.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are exploded perspective views of the embodiment, FIG. 3 is a perspective view showing a configuration of the inner surface side of the upper case, FIG. 4 is a perspective view showing a completed state, and FIG. FIG. 5B is a schematic explanatory view showing the flow of the first air occurring inside the housing, and FIG. 5C is a schematic illustration showing the flow of the second air occurring inside the housing. FIG.

  As shown in FIGS. 1 and 2, an electronic control unit 1 incorporating the heat dissipation structure of the present embodiment includes a circuit board 10 that is held in a substantially horizontal posture, and an upper case that accommodates the circuit board 10 therein ( Cover) 20 and a lower case 30, a sealed housing 5, a connector 19 attached to an end of the circuit board 10, and a respiratory filter 50 attached to the upper case 20. 4 is mounted on a vehicle body panel (not shown) in an assembled state as shown in FIG. Further, in the electronic control unit 1, for example, the height of the housing 5 is determined in accordance with the maximum height of electronic components 12A and 12B (described later) mounted on the circuit board 10, and in particular, the area X where the temperature becomes high The height of the housing 5 is changed according to the area Z where the temperature is low. As a result, heat can be reliably radiated even if the heat generation amount of the heat generating component increases.

  The circuit board 10 is mounted with a large number of electronic components 12A and 12B including heat generating components such as resistors, IPDs, and power supply devices, for example. As shown in FIG. 4 and FIG. The low temperature side C and the anti-connector 19 side, which are considered to have high heat dissipation away from the heat generating component, are the high temperature side H where there are many heat generating components. A heat generating component such as a power supply device is disposed on the low temperature side C, and a heat generating component such as a resistor is disposed on the high temperature side H.

  In the assembled state, the upper surface plate 21 of the upper case 20 covers the upper surface of the circuit board 10, the lower surface plate 31 of the lower case 30 covers the lower surface of the circuit board 10, and the peripheral portions 22 of the upper case 20 and the lower case 30. , 32 are coupled together, the housing 5 is assembled, and the peripheral edge of the circuit board 10 is supported by the housing 5. A ventilation space 40 on the upper side of the board is secured between the circuit board 10 and the upper surface plate 21 of the upper case 20, and a ventilation space 42 on the lower side of the board is provided between the circuit board 10 and the lower surface plate 31 of the lower case 30. It is secured.

  Further, as shown in FIGS. 1 and 2, a cutout 29 for taking out a connector 19 connected to an external electric wire or device is provided at the end of the upper case 20 on the low temperature side C. On the side of the face plate 21 opposite to the connector (high temperature side H), there is provided a filter mounting portion 28 for mounting a respiratory filter 50 that allows ventilation inside and outside while maintaining dustproof and waterproof properties. Specifically, it is located on the high temperature side H of the upper case 20 opposite to the upper case 20 on which the connector 19 is placed at a position separated from the low temperature side C (connector side), that is, a relatively high ventilation space described later. A breathing filter 50 is provided on the low ventilation space 40A side. In addition, heat radiating fins 27 are provided on the outer surface of the upper case 20 on the low temperature side C.

  Further, as a first characteristic point in the electronic control unit 1, the low temperature side C (connector) is higher than the height of the space from the circuit board 10 to the upper surface plate 21 of the upper case 20 on the high temperature side H (non-connector side). A step is provided on the upper surface plate 21 of the upper case 20 so that the height of the space from the circuit board 10 to the upper surface plate 21 of the upper case 20 is larger.

  Specifically, as shown in FIG. 4, the region on the high temperature side H is the first area X, the region between the high temperature side H and the low temperature side C is the second area Y, and the region on the low temperature side C is the third area Z. In this case, the upper surface plate 21A of the first area X, the upper surface plate 21B of the second area Y, and the upper surface plate 21C of the third area Z are formed so as to increase in height stepwise. Accordingly, as shown in FIG. 5B, the heights h1, h2, and h3 of the ventilation spaces 40A, 40B, and 40C between the upper surface plates 21A, 21B, and 21C of the areas X, Y, and Z and the circuit board 10 are obtained. However, the relationship is “h1 <h2 <h3”.

  Further, as a second characteristic point in the electronic control unit 1, as shown in FIG. 5C, the low temperature side C and the high temperature side H inside the housing 5 are respectively located on the upper side of the circuit board 10. Ventilation passages 15 and 16 that allow air to flow between the ventilation space 40 and the lower ventilation space 42 are provided.

  As the ventilation paths 15 and 16, through holes 15 and 16 formed in the circuit board 10 are used. In this example, the first through hole 15 is a positioning hole for inserting a pin 26 (see FIG. 2) for positioning the circuit board 10 and the housing 5, and the pin 26 is positioned after the circuit board 10 is positioned. Is used as a ventilation path 15. The second through-hole 16 is a hole for engaging the locking claw 19A for fixing the connector 19, and a gap with the engaged claw 19A is used as the air passage 16. . However, the shape of the air passages 15 and 16 is not limited to the hole, and the shape of the groove between the circuit board 10 and the lower case 30 is not limited. Any shape can be used as long as ventilation is obtained between them, and the number is not particularly limited.

  Next, the operation will be described.

  When the electronic components 12A and 12B mounted on the circuit board 10 generate heat, the inside is filled with hot air. As shown in FIG. 5 (b), this hot air passes through the height h2 of the intermediate ventilation space 40B in order from the height h1 of the ventilation space 40A on the high temperature side H, and in turn, in the ventilation space 40C on the low temperature side C. Due to the height h3 being larger, convection occurs in the ventilation space 40 between the circuit board 10 and the upper case 20 as shown by the arrow F1. Therefore, air convection is actively generated inside the sealed housing 5, whereby the heat generated on the high temperature side H can be efficiently guided to the low temperature side C to be dissipated, thereby improving the overall cooling efficiency. be able to. In particular, since the connector 19 and the heat radiation fin 27 are provided on the low temperature side C (third area Z), both the heat radiation effect to the external harness and the like through the connector 19 and the heat radiation effect by the heat radiation fin 27 are expected. Therefore, the heat on the high temperature side H can be released through the low temperature side C more efficiently. The air flow as indicated by the arrow F1 may be reversed depending on the mounting position of the electronic components 12A and 12B on the circuit board 10, the uneven shape of each part of the housing 5, and the like. Cooling can be promoted.

  In addition, since the air passages 15 and 16 are secured on the low temperature side C and the high temperature side H inside the housing 5, as shown in FIG. Since an air flow as indicated by an arrow F2 occurs between the side ventilation space 42, convection occurs in a wide area of the space in the housing 5, and cooling is promoted. The air flow as indicated by the arrow F2 may be reversed depending on the temperature distribution in the housing 5, the positions of the air passages 15 and 16, and the like, but at this time, cooling by convection can be promoted.

  In addition, since the breathing filter 50 is provided on the high temperature side H, heat generated on the high temperature side H can be released through the breathing filter 50 as shown by an arrow F3 in FIG. Efficiency can be further increased.

  Furthermore, since the breathing filter 50 is provided on the side of the ventilation space 40A where the height of the ventilation space is relatively low, the outer size is advantageous, and the heat generated from the electronic component 12A does not fill the narrow space. Heat can be radiated more efficiently than the respiratory filter 50.

  In addition, when the electronic control unit 1 is mounted on the vehicle, even when the electronic control unit 1 is arranged so that the low temperature side C is lower than the high temperature side H, the heat that has risen due to the convection is removed from the breathing filter. Since heat can be released through 50, sufficient cooling performance can be exhibited. Furthermore, if the pressure inside the housing 5 decreases, cool air from the outside can be sucked through the breathing filter 50 and the inside of the housing 5 can be cooled.

  As described above, according to the electronic control unit 1 of the present embodiment, efficient heat dissipation is possible, and since the breathing filter 50 is provided, the mounting posture on the vehicle body is not significantly restricted. I'm going to live.

  In the case of the above embodiment, the case where the top plate 21 is formed in a staircase shape is shown, but the shape of the top plate 21 is not limited to a staircase shape, and the top plate 21 is provided with a gradient to allow ventilation. The heights h1, h2, and h3 of the spaces 40A, 40B, and 40C may be changed. At this time, the gradient may be partly or entirely, and may be a shape in which a plurality of gradients or stepped steps are combined.

  In the above embodiment, the through holes formed in the circuit board 10 are used as the air passages 15 and 16, but a gap is secured between the peripheral edge of the circuit board 10 and the housing 5, and the gap is formed. It can also be used as the air passages 15 and 16.

DESCRIPTION OF SYMBOLS 1 Electronic control unit 5 Case 10 Circuit board 12A, 12B Electronic component 15, 16 Ventilation path 19 Connector 20 Upper case 21 Upper surface board 27 Radiation fin 30 Lower case 31 Lower surface board 40 Ventilation space above board | substrate 42 Ventilation space below board | substrate 50 Respiration filter H High temperature side C Low temperature side

Claims (4)

An electronic component including a heat-generating component in a sealed casing composed of an upper case and a lower case, with an upper surface covered by the upper surface plate of the upper case and a lower surface covered by the lower surface plate of the lower case. In the electronic control unit in which the mounted circuit board is installed, the side with the heat generating component in the plane along the circuit board is the high temperature side, and the side away from the heat generating component is the low temperature side,
The height of the space from the circuit board to the upper surface plate of the upper case on the low temperature side is larger than the height of the space from the circuit board to the upper surface plate of the upper case on the high temperature side, A heat dissipation structure for an electronic control unit, wherein a step or gradient is provided on an upper surface plate of the upper case.   2. The electronic control according to claim 1, wherein a connector for connecting to an external electric wire or device is provided on the low temperature side, and a heat radiating fin is provided on an outer surface of the upper case on the low temperature side. Unit heat dissipation structure.   An air passage that allows air to flow between the upper space and the lower space of the circuit board is provided on each of the low temperature side and the high temperature side inside the housing. Control unit heat dissipation structure.   The respiratory filter which enables ventilation | gas_flowing inside and outside is provided in the upper surface board of the said upper case in the said high temperature side, maintaining dustproof and waterproofness. Heat dissipation structure for electronic control unit as described in 1.

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