Electronic control device

Abstract

An electronic control device comprises: a substrate to which an electronic component is mounted; a housing that houses the substrate mounted with the electronic component; a plurality of heat dissipation fins that protrude outward from the outer surface portion of the housing; an outer thick portion; an inner thick portion; and a thin portion that connects the outer thick portion and the inner thick portion. The outer thick portion is formed at a position, on the outer surface portion of the housing, facing the electronic component mounted on the substrate, and protrudes outward from the outer surface portion. The inner thick portion is formed at a position, on the inner surface portion of the housing, facing the electronic component mounted on the substrate, and protrudes from the inner surface portion toward the electronic component. The thickness of the thick portion composed of the outer thick portion, the inner thick portion, and the thin portion is formed to be thicker than the average thickness of the housing. Furthermore, the heat dissipation fins are formed on the outer thick portion.

Description

Electronic control unit

[0001] The present invention relates to an electronic control device.

[0002] An automobile is equipped with an electronic control unit having electronic components that control the automobile. To dissipate heat from the electronic components, the electronic control unit has a heat dissipation structure that thermally connects a heat dissipation block and a heat dissipation member to dissipate heat.

[0003] One example of a technology related to heat dissipation from electronic components is described in Patent Document 1. Patent Document 1 describes an electronic control device 1 that has a heat transfer material that is provided between the electronic component and a heat dissipation section and thermally coupled to the electronic component, and an interposing portion that is provided between an area of ​​the electronic component that is not thermally coupled to the heat transfer material and the heat transfer material. Patent Document 1 also describes that the electronic control device includes a heat transfer member that is thermally coupled to the electronic component and the heat transfer material.

[0004] Japanese Patent Application Laid-Open No. 2020-202329

[0005] In recent years, demand for advanced driver assistance systems (hereinafter referred to as ADAS) and autonomous driving (hereinafter referred to as AD) systems has increased, accelerating the development of autonomous driving technologies for automobiles. Furthermore, as electronic control devices become more sophisticated, the amount of heat generated by electronic components mounted on the devices has increased. As a result, the technology described in Patent Document 1 has the problem of being unable to sufficiently dissipate heat from electronic components that generate increased amounts of heat.

[0006] In consideration of the above problems, an object of the present invention is to provide an electronic control device that can improve the heat dissipation effect.

[0007] To solve the above problems and achieve the object, an electronic control device includes a substrate on which electronic components are mounted, a housing that houses the substrate on which the electronic components are mounted, a plurality of heat dissipation fins that protrude outward from the outer surface of the housing, an outer thick portion, an inner thick portion, and a thin portion that connects the outer thick portion and the inner thick portion. The outer thick portion is formed on the outer surface of the housing at a position facing the electronic components mounted on the substrate and protrudes outward from the outer surface. The inner thick portion is formed on the inner surface of the housing at a position facing the electronic components mounted on the substrate and protrudes from the inner surface toward the electronic components. The thickness of the thick portion consisting of the outer thick portion, the inner thick portion, and the thin portion is greater than the average thickness of the housing. The heat dissipation fins are formed on the outer thick portion.

[0008] According to the electronic control device having the above configuration, the heat dissipation effect can be improved.

[0009] FIG. 1 is a perspective view of an electronic control device according to a first embodiment; FIG. 2 is a perspective view of an electronic control device according to the first embodiment, viewed from the opposite side to FIG. 1; FIG. 3 is a cross-sectional view of an electronic control device according to the first embodiment; FIG. 4 is a perspective view of a conventional electronic control device; FIG. 5 is a cross-sectional view of a conventional electronic control device; FIG. 6 is a graph showing the relationship between the thickness of a thick portion and the height of a heat dissipation fin and the temperature rise of an electronic component; FIG. 7 is a graph showing the temperature reduction effect when one thick portion is formed for two electronic components; FIG. 8 is a cross-sectional view of an electronic control device according to a second embodiment; FIG. 9 is a cross-sectional view showing a comparison with an electronic control device of a reference example;

[0010] Hereinafter, an embodiment of an electronic control device will be described with reference to Figures 1 to 9. Note that common members in each figure are given the same reference numerals.

[0011] 1. First embodiment 1-1. Configuration example of electronic control device First, the configuration of an electronic control device according to a first embodiment (hereinafter referred to as "this example") will be described with reference to Figures 1 to 7. Figures 1 and 2 are perspective views showing the electronic control device. Figure 3 is a cross-sectional view showing the electronic control device.

[0012] The device shown in Figures 1 to 3 and 2 is an electronic control device that is mounted on an automobile and has an electronic circuit that controls the automobile. As shown in Figures 1 and 2, the electronic control device 1 has a first housing 2 and a second housing 3 that constitute a housing. The first housing 2 is formed like a hollow lid with one side open. The second housing 3 is formed like a substantially flat plate. The second housing 3 is fixed to the first housing 2 via a fixing screw 4 so as to close the opening of the first housing 2.

[0013] 3 , the electronic control device 1 has a circuit board 6 and an electronic component 8, which is a heat-generating component, housed inside the first housing 2 and the second housing 3. The circuit board 6 is placed on the second housing 3. A space is formed between the mounting surface of the circuit board 6 and the first housing 2.

[0014] The electronic component 8 is mounted on the substrate 6 via a conductive bonding member 7 made of solder or the like. A heat conductive member 9 is interposed between the electronic component 8 and the first housing 2.

[0015] A plurality of heat dissipation fins 10 are formed on the outer surface 2a, which is the outer surface of the first housing 2. The heat dissipation fins 10 protrude from the outer surface 2a of the first housing 2 in a direction away from the second housing 3. In addition, an outer thick portion 11 is formed on the outer surface 2a of the first housing 2 at a position facing the electronic components 8. The outer thick portion 11 protrudes from the outer surface 2a of the first housing 2 in a direction away from the electronic components 8, i.e., toward the outside of the first housing 2.

[0016] The heat dissipation fins 10 are also formed on the external thick portion 11. The heat dissipation fins 10 on the external thick portion 11 are set shorter than the heat dissipation fins 10 in other locations. In other words, the height l of the heat dissipation fins 10 formed on the external thick portion 11 plus the thickness of the external thick portion 11 is set to be the same as or shorter than the height L of the other heat dissipation fins 10. This prevents the maximum outer diameter of the first housing 2 from becoming larger only in the location where the external thick portion 11 is formed.

[0017] If the size of the housing allows, the length obtained by adding the height 1 of the heat dissipation fin 10 formed on the outer thick portion 11 to the thickness of the outer thick portion 11 may be longer than the height L of the other heat dissipation fins 10. This can further improve the heat dissipation effect.

[0018] 3, an internal thick portion 12 is formed at a position facing the electronic component 8 on the inner surface, which is the inner face of the first housing 2. The internal thick portion 12 protrudes from the inner surface of the first housing 2 toward the electronic component 8, i.e., toward the inside of the first housing 2. The internal thick portion 12 is formed at a position on the first housing 2 where the external thick portion 11 is provided.

[0019] In this example, the thickness of the external thick portion 11 is equal to or greater than the thickness of the internal thick portion 12. Herein, the portion connecting the external thick portion 11 and the internal thick portion 12 is referred to as a thin portion. The thickness of the thick portion consisting of the external thick portion 11, the internal thick portion 12, and the thin portion is greater than the average thickness of the first housing 2. Hereinafter, the internal thick portion 12, the external thick portion 11, and the thin portion connecting the internal thick portion 12 and the external thick portion 11 are collectively referred to as the thick portion. A thermally conductive member 9 is interposed between the internal thick portion 12 and the electronic components 8. Heat generated by the electronic components 8 is transferred via the thermally conductive member 9 to the internal thick portion 12, the external thick portion 11, and the heat dissipation fins 10. The electronic control device 1 of this example cools the electronic components 8 by natural air cooling using the heat dissipation fins 10, the internal thick portion 12, and the external thick portion 11.

[0020] 3, the internal thick portion 12 and the external thick portion 11 are formed separately for each of the electronic components 8 mounted on the substrate 6. That is, the internal thick portion 12 and the external thick portion 11 are formed independently for each electronic component 8. Hereinafter, the internal thick portion 12, the external thick portion 11, and the thin portion connecting the internal thick portion 12 and the external thick portion 11 will be collectively referred to simply as the thick portion. Two adjacent thick portions in the first housing 2 are connected by a thin portion that is another part of the internal thick portion 12 and the external thick portion 11 in the first housing 2.

[0021] 1-2. Conventional Example Next, a conventional electronic control device 100 will be described with reference to Figures 4 and 5. Figure 4 is a perspective view showing the conventional electronic control device 100, and Figure 5 is a cross-sectional view showing the conventional electronic control device 100. Note that parts that are common to the electronic control device 1 of this example are given the same reference numerals, and duplicated explanations will be omitted.

[0022] 4 and 5 , the electronic control device 100 has a first housing 102 that constitutes a housing, and a substrate 6 housed in the housing. Electronic components 8 are mounted on the substrate 6 via conductive bonding members 7. A plurality of heat dissipation fins 110 are formed on an outer surface 102a of the first housing 102. An inner thick portion 112 is formed on the inner surface of the first housing 102 at a position facing the electronic components 8. The inner thick portion 112 protrudes from the inner surface of the first housing 102 toward the electronic components 8, i.e., toward the inside of the first housing 2.

[0023] 5 does not have a configuration equivalent to the outer thick portion 11 of the present embodiment. Therefore, in the conventional electronic control device 100, the heat dissipation fins 110 alone are not able to ensure sufficient heat dissipation performance.

[0024] In contrast, according to the electronic control device 1 of this embodiment, not only the internal thick portion 12 but also the external thick portion 11, whose thickness expands outward, is provided locally at the location of thermal junction with the heat-generating electronic component 8 in the first housing 2. This allows the external thick portion 11 to increase the thermal capacity of the first housing 2, thereby improving heat dissipation performance. Furthermore, by providing heat dissipation fins 10 on the external thick portion 11, heat dissipation performance can be further improved. As a result, heat can be sufficiently dissipated even from electronic components that generate increased amounts of heat, such as electronic control devices used in advanced driver assistance systems (hereinafter referred to as ADAS) and autonomous driving (hereinafter referred to as AD) systems.

[0025] Furthermore, the provision of the external thick portion 11 ensures the necessary amount of heat transfer to the air, allowing the electronic components 8 to be cooled by natural air cooling. Alternatively, forced air cooling using a fan may be used as a cooling method.

[0026] 1-3. Thickness of Thick Portions and Height of Heat Dissipation Fins Next, with reference to Fig. 6, the relationship between the thickness of the internal thick portion 12 and the external thick portion 11, which are the thick portions of the first housing 2, and the height l of the heat dissipation fins provided on the external thick portion 11 will be described. Fig. 6 is a graph showing the relationship between the thickness of the thick portions, the height of the heat dissipation fins, and the temperature rise of the electronic component. The vertical axis in Fig. 6 represents the temperature rise ΔTj of the electronic component 8.

[0027] 3, the thickness t of the thick portion of the first housing 2 is the thickness including the inner thick portion 12, the outer thick portion 11, and the thin portion. The horizontal axis shown in FIG. 6 represents (thick portion thickness t) / (thick portion thickness t+height l of the heat dissipation fins arranged in the outer thick portion 11).

[0028] The graph shown in Fig. 6 shows that the relationship is not linear but has an inflection point. As shown in Fig. 6, when (thickness t of the thick portion) / (thickness t of the thick portion + height l of the heat dissipation fins arranged on the outer thick portion 11) is 0.4 to less than 1, the heat dissipation performance can be optimized.

[0029] Furthermore, in the electronic control device 1 of this embodiment, the volume of the thick-walled portion is set based on the heat generation amount of the heat-generating electronic component 8 so that a peak inflection point occurs, as shown in FIG. 6 . The thickness t and height l of the thick-walled portions 11, 12 and the heat dissipation fin 10 are then set near the region where the peak inflection point occurs. This maximizes heat dissipation performance for a given housing size. However, if multiple electronic components (heat-generating components) 8 are placed in one thick-walled portion, the thermal capacity of the thick-walled portion tends to be insufficient, i.e., the inflection point tends not to occur, as shown in FIG. 7 (described later). Therefore, it is preferable to divide the thick-walled portion according to the number of electronic components 8.

[0030] 1-4. Number of Electronic Components and Number of Thick-Walled Portions Next, the relationship between the number of electronic components and the number of thick-walled portions will be described with reference to FIG. 7. FIG. 7 is a graph showing the temperature reduction effect when one thick-walled portion is formed for two electronic components 8. The vertical axis in FIG. 7 represents the temperature rise ΔTj of the electronic component 8. The horizontal axis in FIG. 7 represents (thick-walled portion thickness t) / (thick-walled portion thickness t + height l of the heat dissipation fins arranged in the outer thick-walled portion 11).

[0031] As shown in Figure 7, when one thick portion is formed for two electronic components 8, unlike the example shown in Figure 6, no inflection point is observed and the relationship is close to linear. Furthermore, when the ratio (thickness t of the thick portion) / (thickness t of the thick portion + height l of the heat dissipation fins arranged in the external thick portion 11) is 0.5, the temperature rise ΔTj of the electronic component 8 reaches 164°C or 163°C. In contrast, when one thick portion is formed for one electronic component 8 as shown in Figure 6, the temperature rise ΔTj of the electronic component 8 is limited to 57.75°C when the ratio (thickness t of the thick portion) / (thickness t of the thick portion + height l of the heat dissipation fins arranged in the external thick portion 11) is 0.5.

[0032] This is because, when one thick portion is formed for multiple electronic components 8, heat from the multiple electronic components 8 concentrates in one thick portion, causing thermal interference between the electronic components 8 and resulting in insufficient thermal capacity of the thick portion. Therefore, as shown in Fig. 3, it is preferable to form the inner thick portion 12 and the outer thick portion 11 independently for each electronic component 8. This prevents heat from the multiple electronic components 8 from concentrating in one inner thick portion 12 and outer thick portion 11, which would result in insufficient thermal capacity and heat transfer.

[0033] That is, by providing the divided internal thick portion 12 and external thick portion 11 for each electronic component 8, heat transfer between the electronic components 8 is suppressed at the thin portions other than the internal thick portion 12 and external thick portion 11 in the first housing 2. This reduces the mutual thermal influence of the multiple electronic components 8. By dispersing the heat dissipation portions in this way, the heat dissipation performance of the heat dissipation fins 10 and the internal thick portion 12 and external thick portion 11 can be improved.

[0034] 2. Second Embodiment Next, an electronic control device according to a second embodiment will be described with reference to Fig. 8. Fig. 8 is a perspective view showing a protective member of the electronic control device according to the second embodiment.

[0035] The electronic control device according to the second embodiment differs from the electronic control device 1 according to the first embodiment in the relationship between the thickness of the outer thick portion and the inner thick portion. Therefore, parts common to the electronic control device 1 according to the first embodiment are assigned the same reference numerals and redundant explanations will be omitted.

[0036] 8, the first housing 2A is provided with heat dissipation fins 10, an internal thick portion 12, and an external thick portion 11A. In the second embodiment, the external thick portion 11A is thinner than the internal thick portion 12. Even if the external thick portion 11A is thinner than the internal thick portion 12, the external thick portion 11A can increase the heat capacity of the first housing 2, thereby improving heat dissipation performance.

[0037] 8, the length of the heat dissipation fins 10 arranged in the outer thick portion 11A can be made longer than that of the electronic control device 1 according to the first embodiment. Therefore, the electronic control device according to the second embodiment is suitable for forced air cooling in which a fan is used to blow air onto the heat dissipation fins 10. In contrast, for natural air cooling, the electronic control device 1 according to the first embodiment, which has a thicker outer thick portion 11A to enhance the heat capacity and heat dissipation effect, is suitable.

[0038] The other configurations are the same as those of the electronic control unit 1 according to the first embodiment, and therefore description thereof will be omitted. The electronic control unit according to the second embodiment can also obtain the same effects as those of the electronic control unit 1 according to the first embodiment described above.

[0039] 3. Comparison with Reference Example Next, a comparison between the electronic control device of the reference example and the electronic control device 1 of this example will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view showing a comparison with an electronic control device when the thickness of the outer thick portion and the inner thick portion are changed while the thickness of the thick portion is the same. Figs. 9(a) and 9(c) are cross-sectional views showing the electronic control device of the reference example, and Fig. 9(b) is a cross-sectional view showing the electronic control device 1 of this example.

[0040] The electronic control device shown in Fig. 9(a) is an electronic control device that does not have an external thick portion. In the conventional electronic control device shown in Fig. 9(a), if the thickness of the internal thick portion 112 is increased to ensure thermal capacity, the internal thick portion 112 that serves as a heat sink will expand significantly toward the inside of the first housing 102. As a result, there is a problem in that the internal thick portion 112 causes an increase in the temperature around the electronic component 8, which is a heat-generating component.

[0041] Furthermore, as the thickness of the inner thick portion 112 increases, the limit distance for mounting the electronic components 8 also increases, which causes a problem of a decrease in the mounting density of the electronic components 8 on the substrate 6.

[0042] The electronic control device shown in Figure 9(c) does not have an internal thick portion, but has an external thick portion 11B on the outside of the first housing 2B at a location facing the electronic component 8. In this case, the first housing 2B is closer to the board 6, which may cause other relatively tall electronic components to interfere with the first housing 2B. Furthermore, not having an internal thick portion reduces the space inside the housing, making it easier for heat from the electronic component 8 to accumulate inside the housing. This results in the problem of an increase in temperature inside the housing.

[0043] Furthermore, in order to prevent the internal space of the housing from shrinking, it is necessary to increase the thickness of the heat conducting member 9, which also poses the problem of increased costs.

[0044] In contrast, according to the electronic control device 1 of this example, by providing the first housing 2 with the internal thick portion 12, it is possible to prevent the space inside the housing from being reduced and to prevent heat from the electronic components 8 from being trapped inside the housing. Furthermore, it is possible to reduce the thickness of the heat conduction member 9, thereby reducing costs. Furthermore, as described above, the external thick portion 11 and the internal thick portion 12 can increase the thermal capacity of the first housing 2 and improve heat dissipation performance.

[0045] The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications are possible within the scope of the invention as defined in the claims. It is also possible to replace a part of the configuration of one embodiment with a configuration of another embodiment, or to add a configuration of another embodiment to a configuration of one embodiment. Furthermore, it is also possible to add, delete, or replace a part of the configuration of another embodiment with another configuration.

[0046] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but also include "parallel" and "orthogonal" and may also mean a "substantially parallel" or "substantially orthogonal" state within a range in which the functions can be exerted.

[0047] DESCRIPTION OF SYMBOLS 1...Electronic control device, 2, 2A...First housing, 2a...External surface portion, 3...Second housing, 6...Substrate, 7...Conductive bonding member, 8...Electronic component (heat-generating component), 9...Heat-conducting member, 10...Heat dissipation fin, 11...External thick portion, 11A...External thick portion, 12...Internal thick portion

Claims

1. An electronic control device comprising: a board on which electronic components are mounted; a housing that houses the board with the electronic components mounted thereon; a plurality of heat dissipation fins protruding outward from an exterior portion that is the outer surface of the housing; an external thick portion formed on the exterior portion of the housing at a position facing the electronic components mounted on the board and protruding outward from the exterior portion; and an internal thick portion formed on the interior portion of the housing at a position facing the electronic components mounted on the board and protruding from the interior portion toward the electronic components, and a thin portion connecting the external thick portion and the internal thick portion, wherein the thickness of the thick portion composed of the external thick portion, the internal thick portion and the thin portion is formed to be thicker than an average thickness of the housing, and the heat dissipation fins are formed on the external thick portion.

2. The electronic control device according to claim 1, wherein the height of the heat dissipation fins formed on the external thick portion plus the thickness of the external thick portion is set to be the same as or shorter than the height of the heat dissipation fins formed in a position other than the external thick portion.

3. The electronic control device according to claim 1, wherein a plurality of electronic components are mounted on the substrate, and the inner thick portion and the outer thick portion are formed separately for each electronic component.

4. The electronic control device according to claim 1, wherein the thickness of the outer thick portion is equal to or greater than the thickness of the inner thick portion.

5. The electronic control device according to claim 1, wherein a heat conductive member is interposed between the internal thick portion and the electronic component.

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