electronic control device

Abstract

An electronic control device is provided with a heat generating component mounted on a surface of a circuit board of the electronic control device on which a connector is mounted. A metal case that houses the circuit board has an opposing surface that opposes the surface of the circuit board on which the heat generating component is mounted. A first fin that protrudes toward the surface on which the heat generating component is mounted is provided on the opposing surface of the case. The first fin overlaps the heat generating component in a thickness direction of the circuit board.

Description

TECHNICAL FIELD

[0001] The present application relates to an electronic control device that has a housing of a shape that releases heat of a heat generating component to the outside. BACKGROUND

[0002] In a vehicle, an electronic control device is mounted as an engine control unit, an automatic transmission control unit. The electronic control device has a circuit board on which an electronic component is mounted. Among the electronic components, there is a heat generating component such as a CPU, a semiconductor switching element, and the like that generates heat according to operation. In Japanese Patent Application Publication No. 2013-197405, a technique is disclosed in which heat generated by the heat generating component is discharged to the atmosphere via a frame that houses the circuit board.

[0003] The frame of the electronic control device of Japanese Patent Application Publication No. 2013-197405 has a box-shaped housing that is integrally formed of a metal material, and a cover that covers the circuit board housed in the housing. On the housing, a heat dissipation portion is formed at a position that opposes the heat generating component. The heat dissipation portion is thin-walled compared to the surrounding portions. The heat dissipation portion has a protrusion that protrudes from the inside of the housing toward the heat generating portion, and a recess that opens to the outside of the housing at a position in the thickness direction of the protrusion.

[0004] Heat of the heat generating component easily transfers to the protrusion that is close to the heat generating component, and heat that transfers to the recess is dissipated from the recess of the heat dissipation portion that is thin-walled, and the periphery of the heat dissipation portion. SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, as described above, the recess is provided at a position in the thickness direction of the protrusion on the outer surface of the housing. By providing the recess, it is possible to improve the heat dissipation and fix the thickness of the housing. When the thickness of the housing is fixed, it is also possible to ensure the moldability of the housing that is made of metal. However, if the recess is formed on the outer surface of the housing, the shape of the outer surface of the housing becomes complex, and the manufacturing cost of the mold for molding the housing also becomes high. It is desirable to provide an electronic control device that has a simple outer surface of the housing and also has heat dissipation.

[0007] The present application relates to an electronic control device that has a housing of a shape that releases heat of a heat generating component to the outside.

[0008] The housing of the electronic control device has an opposing surface that opposes one surface of the circuit board. A first fin that protrudes toward one surface of the circuit board is provided on the opposing surface of the housing. The first fin overlaps the high heat generating component in the thickness direction of the circuit board. Therefore, heat generated from the high heat generating component is transferred to the first fin that is located directly below the high heat generating component, and is dissipated from the housing to the outside via the first fin.

[0009] Further, the first fin is thin plate-shaped, and the area of the end surface of the first fin is small. If a protrusion having a prescribed size is provided to the end surface as in Patent Document 1, a recess must be provided to the opposite surface in order to maintain moldability. On the other hand, the first fin is thin plate-shaped. In order to maintain moldability of the metal housing, a recess corresponding to the first fin does not need to be formed in the opposite surface 41 of the surface on which the first fin is formed. The opposite surface is planar, and the outer shape of the housing becomes simple.

[0010] Thus, an electronic control device having a housing with a simple outer surface and high heat dissipation can be configured.

[0011] Preferably, a second fin that protrudes toward one surface of the circuit board is provided to the opposite surface of the housing. When viewed in the thickness direction of the circuit board, the second fin is positioned between the high heat generating component and the low heat generating component. In a case where the spacing between the housing and the circuit board is set to a prescribed size in a manner that causes air within the housing to circulate, heat emitted from the high heat generating component flows toward the low heat generating component by convection. Therefore, by providing the second fin between the high heat generating component and the low heat generating component, hot air can be blocked. The low heat generating component can be prevented from being heated. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is an exploded perspective view of an electronic control device of an embodiment.

[0013] Figure 2 is a perspective view of a housing that can accommodate Figure 1 a circuit board shown in FIG. 1.

[0014] Figure 3 is a top view of a circuit board and a housing viewed in the thickness direction of the circuit board shown in FIG. 1. Figure 1

[0015] Figure 4 is a sectional view of a portion of an electronic control device that includes a high heat generating component, viewed in the insertion direction of a connector shown in FIG. 1. Figure 1

[0016] Figure 5 is a diagram that explains the effect of a second fin formed to Figure 3 a housing shown in FIG. 1. DETAILED DESCRIPTION

[0017] Hereinafter, an embodiment will be described with reference to the drawings.

[0018] <EMBODIMENT>

[0019] In Figure 1 ​​An electronic control device 10 that can be applied to an engine control unit or the like is shown in FIG. 1. The electronic control device 10 is provided with: a circuit board 30 on which electronic components are mounted; a metal housing 40 that houses the circuit board 30; and a cover 20 that is assembled to the housing 40 and covers the circuit board 30. For ease of explanation, the thickness direction of the circuit board 30 is set as the up-down direction. In the figure, Up indicates the upper side, and Dn indicates the lower side. Further, the up-down direction does not necessarily correspond to the state of the electronic control device 10 mounted on a vehicle.

[0020] (Circuit board)

[0021] The circuit board 30 is a rectangular printed wiring board on which a wiring circuit pattern (not shown) is formed on the front and back surfaces or inside of a board material made of, for example, glass epoxy resin. The wiring circuit pattern is electrically connected to the electronic components.

[0022] Specifically, on the lower surface 31 (one surface, the surface on the side of the housing 40) of the circuit board 30, a plurality of (for example, four) high heat generating components 51 to 54 that are electronic components (arithmetic processing devices, transistors, ICs, and the like) that easily generate heat, and a plurality of (for example, three) low heat generating components 56 to 58 that are electronic components (capacitors, coils, and the like) that do not generate heat compared to the high heat generating components are mounted. Further, on the upper surface 32 (the other surface, the surface on the side of the cover 20) of the circuit board 30, electronic components are also mounted, but the illustration and explanation of the electronic components are omitted.

[0023] On the circuit board 30, a positioning hole 33 that determines the position of the circuit board 30 with respect to the housing 40, and a through hole 35 through which a screw 34 for fixing the circuit board 30 with respect to the housing 40 can pass are formed.

[0024] (Connector)

[0025] On the edge of one side in the long side direction of the lower surface 31 of the circuit board 30, a first connector 60 and a second connector 70 that face the outside are mounted. The first connector 60 and the second connector 70 can be connected to connectors (not shown) on the side of a vehicle, respectively.

[0026] The first connector 60 is provided with a first terminal 61 that is electrically connected to the wiring circuit pattern of the circuit board 30, and a first base 62 that supports the first terminal 61. The first base 62 is in a plate shape and is arranged perpendicularly to the lower surface 31 of the circuit board 30.

[0027] The second connector 70 is provided with a second terminal 71 that is electrically connected to the wiring circuit pattern of the circuit board 30, and a second base (not shown) that supports the second terminal 71. The second base is in a plate shape and is arranged perpendicularly to the lower surface 31 of the circuit board 30.

[0028] (Cover)

[0029] The cover 20 is a sheet metal product that is lightweight and low cost compared to a metal material (aluminum die-cast manufacture). The cover 20 is formed with a positioning hole 21 that determines the position of the cover 20 with respect to the housing 40, and a through hole that enables a screw 22 for fixing the cover 20 with respect to the housing 40 to pass through.

[0030] (Housing)

[0031] Referring to Figure 1 and Figure 2 The housing 40 is made of a metal such as aluminum that is excellent in thermal conductivity (aluminum die-cast), and is in the form of a box that is open upward. In detail, the housing 40 is integrally composed of a plate-shaped main body portion 41 that opposes the lower surface 31 of the circuit board 30, a support portion 42 that can support the first base portion 62 of the first connector 60 and the second base portion of the second connector 70, a connecting portion 43 that connects the main body portion 41 and the support portion 42, and a wall portion 44 that can surround the circuit board 30. The wall portion 44 is not provided at portions where the first connector 60 and the second connector 70 are arranged.

[0032] In the center of the edges of the four corners of the inside of the housing 40 on the side opposite the first connector 60 and the second connector 70, support surfaces 45 that support the circuit board 30 are provided. On each support surface 45, an internal screw hole 45a that can be fastened with a screw 34 for fixing the circuit board 30 is formed. In the wall portion 44, an internal screw hole 44a that can be fastened with a screw 22 for fixing the cover 20 is formed.

[0033] In the support portion 42, grooves 42a, 42a that enable the first base portion 62 of the first connector 60 and the second base portion of the second connector 70 to be inserted are formed. The support portion 42 is located at a position lower than the main body portion 41 (a direction away from the circuit board 30 with the thickness direction of the circuit board 30 as a reference). In other words, the support portion 42, the connecting portion 43, and the main body portion 41 are connected to each other in a stepped manner.

[0034] (First and second fins)

[0035] The main body portion 41 of the housing 40 has an opposing surface 41 that opposes the lower surface 31 of the circuit board 30 (a surface on which the high heat generating components 51 to 54 are mounted). In the opposing surface 41 of the housing 40, thin plate-shaped first fins 81 to 83 and second fins 91 to 93 that protrude toward one surface of the circuit board 30 are integrally formed with the main body portion 41.

[0036] The heights of the first fins 81 to 83 and the second fins 91 to 93 are equal when viewed in the thickness direction (the up-and-down direction) of the circuit board 30. The first fins 81 to 83 are each set to be longer than the second fins 91 to 93 when viewed in the insertion direction (refer to arrow L) of the first connector 60 and the second connector 70.

[0037] The thicknesses of the first fins 81 to 83 and the second fins 91 to 93 are equal when viewed in the width direction (refer to arrow W) of the first connector 60 and the second connector 70. The first fins 81 to 83 and the second fins 91 to 93 are adjacent in the width direction (refer to arrow W).

[0038] (Position of first fins)

[0039] Figure 3 is a plan view of the circuit board 30 and the housing 40 viewed in the thickness direction of the circuit board 30. In the thickness direction of the circuit board 30, the first fin 81 overlaps the high heat generating parts 51 and 52. The first fin 82 overlaps the heat generating part 53. The first fin 82 is formed across the stepped portion from the opposing surface 41. The length of the first fin 82 is the longest among the first fins 81 to 83. The first fin 83 overlaps the high heat generating part 54.

[0040] (Position of second fins)

[0041] The second fin 91 is located between the high heat generating part 51 and the low heat generating part 56. The second fin 91 is longer than the low heat generating part 56 (when viewed in the direction of arrow L). The second fin 91 is formed across the connecting portion 43 from the opposing surface 41. The second fin 92 is located between the high heat generating part 53 and the low heat generating part 57. The second fin 92 is longer than the low heat generating part 57 (when viewed in the direction of arrow L). The second fin 93 is located between the high heat generating part 54 and the low heat generating part 58. The second fin 93 is longer than the low heat generating part 58 (when viewed in the direction of arrow L).

[0042] Reference Figure 4 The interval D between the opposing surface 41a of the housing 40 and the lower surface 31 of the circuit board 30 is set so that the air in the housing 40 convectionally flows. In general, the heat flow when there is a temperature difference between the fluid of convection and the object in contact with the fluid is calculated by the following formula.

[0043] Heat flow (W) = surface area of object (m 2 ) x convection heat transfer rate (W / m 2 k) x (surface temperature of object (k) - fluid temperature (k)).

[0044] The distance D from the lower surface 31 of the circuit board 30 to the housing 40 is calculated by formula (1) obtained by transforming the above formula based on the thermal conductivity h of air, the surface area S of the lower surface 31 of the circuit board 30, the surface area temperature Ts of the circuit board 30, the temperature Tq of the air convecting inside the housing 40, and the heat dissipation power Qe of the circuit board 30.

[0045]

Mathematical Formula 1

[0046]

[0047] (Effects of the Example)

[0048] (Height of shell formability based on fins)

[0049] Reference Figure 2 and Figure 3 The housing 40 of the electronic control device 10 has a facing surface 41 opposite to the lower surface 31 of the circuit board 30. First fins 81-83 protruding towards one side of the circuit board 30 are provided on the facing surface 41 of the housing 40. The first fins 81-83 overlap with the high-heat-generating components 51-54 in the thickness direction of the circuit board 30. Therefore, heat generated from the high-heat-generating components 51-54 is transferred to the first fins 81-83 located directly below the high-heat-generating components 51-54, and dissipated to the outside from the main body 41 of the housing 40 via the first fins 81-83.

[0050] The first fins 81-83 are thin plates, and the area of ​​their end faces is small. As in Patent Document 1, when a protrusion of a predetermined size is provided on the end face, a recess must be provided on the opposite side to maintain formability. On the other hand, since the first fins 81-83 are thin plates, it is not necessary to maintain the formability of the metal housing 40 by providing a recess on the opposite side 41b (see [reference]) where the opposing surfaces 41 of the first fins 81-83 are formed. Figure 4 The outer surface of the shell has recesses corresponding to the first fins 81-83. The opposite surface 41b is flat, simplifying the shape of the shell 40.

[0051] Thus, an electronic control device 10 can be constructed with a housing 40 having a simple structure with opposite side 41b and high heat dissipation.

[0052] (Based on the heat insulation effect of the second fin)

[0053] Furthermore, second fins 91 to 93 protruding toward one side of the circuit board 30 are provided on the opposing surface 41 of the housing 40. When viewed along the thickness direction of the circuit board 30 (refer to...), Figure 3The second fin 91 is located between the high heat generating component 51 and the low heat generating component 56. The second fin 92 is located between the high heat generating component 53 and the low heat generating component 57. The second fin 93 is located between the high heat generating component 54 and the low heat generating component 58.

[0054] In a case where the dimension of the interval D (refer to Figure 4 ) is set in a manner that the air in the housing 40 is set to be in a convection, the heat emitted from the high heat generating components 51 to 54 flows toward the low heat generating components 56 to 58. Therefore, by providing the second fins 91 to 93 between the high heat generating components 51 to 54 and the low heat generating components 56 to 58, the high temperature air can be blocked. The low heat generating components 56 to 58 can be inhibited from being heated.

[0055] (Length of the first fin)

[0056] Refer to Figure 3 In addition, the length of the first fins 81 to 83 is longer than the length of any one of the second fins 91 to 93. Therefore, the heat dissipation property of the first fin can be improved.

[0057] The present application is not limited to the embodiment as long as the effects and advantages of the present application can be obtained.

Claims

1. An electronic control device, comprising: Circuit board; A connector, which is mounted on one side of the circuit board and faces outward; A heating element is mounted on the side on which the connector is mounted; A metal housing that houses the circuit board; as well as A cover, which is assembled into the housing and covers the circuit board, The housing has a facing surface opposite to one side of the circuit board, and a plurality of first fins protruding toward the one side of the circuit board are provided on the facing surface of the housing. The plurality of first fins overlap with the heating element in the thickness direction of the circuit board. The housing includes: The main body has the opposing surfaces; A support portion, which, together with the cover, clamps and supports the connector; and The connecting part connects the main body part and the supporting part. The main body, the support, and the connecting part are formed in a stepped shape. The support portion is further away from the one surface of the circuit board than the main body portion. The plurality of first fins include first fins formed from the main body portion of the housing having the opposing surfaces to the support portion.

2. The electronic control device according to claim 1, wherein, A second fin protruding toward one side of the circuit board is provided on the opposite surface of the housing. When viewed along the thickness direction of the circuit board, the second fin is located between the heating element and a low-heating element that generates less heat than the heating element, and... The second fin extends in a manner whose length direction is perpendicular to the arrangement direction of the heating element and the low-heating element.

3. The electronic control device according to claim 2, wherein, When viewed along the thickness direction of the circuit board, the length of the first fin is longer than the length of the second fin.

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