On-vehicle control device

Abstract

The purpose of the present invention is to provide technology whereby a heat sink, a metal case, and a substrate can be fixed without a screw hole being provided in the heat sink. An on-vehicle control device according to the present invention comprises: a substrate that includes a DC-DC converter for boosting or stepping down the supply voltage from a battery, and a control unit that controls switching of the DC-DC converter at a frequency higher than that of an AM band; a heat sink that dissipates heat from the substrate to the outside due to being thermally connected to the substrate; and a metal case that, together the heat sink, surrounds the substrate, and that has an engaging part that engages with the heat sink.

Description

In-vehicle control device

[0001] The present disclosure relates to an in-vehicle control device.

[0002] A configuration has been proposed for an automotive lighting control device that controls automotive lighting fixtures, which includes a board, a lower member on which the board is placed, and a case that cooperates with the lower member to surround the board, with the lower member and case being fixed together with screws.

[0003] JP 2014-99389 A

[0004] Generally, the control frequency of a DC-DC converter that supplies power to an LED in an automotive lamp is about several hundred kHz. At this control frequency, AM band noise is emitted as radio waves from the DC-DC converter, so a filter circuit is generally provided to counter the noise, but this increases costs.

[0005] Therefore, a configuration has been proposed in which the control frequency of the DCDC converter is set to a frequency band higher than the AM band, for example, several MHz. However, while this configuration can reduce noise emissions, it also creates the problem of increased heat generation from the DCDC converter and other components.

[0006] To address this issue, it is conceivable to increase the heat dissipation of the board by placing it on a heat sink, which has a higher heat dissipation capacity, instead of placing the board on a lower member made of sheet metal. However, this poses a new problem: increased costs, since it is difficult to provide screw holes in the heat sink for fastening the heat sink to the case with screws.

[0007] Therefore, the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can fix a heat sink, a metal case, and a substrate without providing screw holes in the heat sink.

[0008] The vehicle control device of the present disclosure comprises a substrate including a DC-DC converter that boosts or lowers the supply voltage from a battery and a control unit that controls the switching of the DC-DC converter at a frequency higher than the AM band, a heat sink that is thermally connected to the substrate and releases heat from the substrate to the outside, and a metal case that cooperates with the heat sink to surround the substrate, the metal case having a fitting portion that fits with the heat sink.

[0009] According to the present disclosure, the metal case that cooperates with the heat sink to enclose the substrate has a fitting portion that fits with the heat sink. With this configuration, the heat sink, the metal case, and the substrate can be fixed together without providing screw holes in the heat sink.

[0010] The objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0011] Fig. 1 is a perspective view showing the configuration of an in-vehicle lighting control device according to embodiment 1. Fig. 2 is a cross-sectional view showing the configuration of an in-vehicle lamp provided with the in-vehicle lighting control device according to embodiment 1. Fig. 3 is a cross-sectional view showing the configuration of an in-vehicle lighting control device according to embodiment 1. Fig. 4 is a cross-sectional view showing the configuration of an in-vehicle lighting control device according to embodiment 1.

[0012] <Embodiment 1> Hereinafter, embodiments will be described with reference to the accompanying drawings. Features described in each of the following embodiments are exemplary, and not all features are necessarily required. In addition, in the following description, similar components in multiple embodiments are denoted by the same or similar reference numerals, and different components will be mainly described. In addition, in the following description, specific positions and directions such as "up," "down," "left," or "right" may not necessarily correspond to positions and directions in actual implementation.

[0013] FIG. 1 is a perspective view showing the configuration of an in-vehicle lighting control device 100 which is an in-vehicle control device according to the first embodiment.

[0014] The in-vehicle lighting control device 100 of FIG. 1 includes an extrusion heat sink 1 which is a heat sink made of, for example, aluminum, a metal case 2 formed of, for example, sheet metal, and a substrate 3 .

[0015] The substrate 3 includes a DC-DC converter (not shown) and a control unit such as an ECU (Electronic Control Unit) (not shown). The DC-DC converter boosts or reduces the voltage supplied from a battery installed in the vehicle or the like to generate a voltage used for lighting the automotive lamp. The control unit controls the switching of the DC-DC converter at a frequency of several MHz (e.g., 2 MHz) higher than the AM band.

[0016] With this configuration, radiation noise is emitted from the substrate 3 when the automotive lighting control device 100 is in operation, but radiation noise in the AM band is suppressed and radiation noise with frequencies higher than the AM band is mainly emitted. As a result, a filter circuit to deal with AM band noise is not required.

[0017] On the other hand, radiation noise of frequencies higher than the AM band is emitted from the substrate 3. Therefore, the substrate 3 is surrounded by the extruded heat sink 1 and the metal case 2, and the metal case 2 is electrically connected to the extruded heat sink 1 via the substrate 3. With this configuration, the extruded heat sink 1 and the metal case 2 can block radiation noise of frequencies higher than the AM band. The electrical connection between the extruded heat sink 1 and the metal case 2 will be described in detail later.

[0018] The substrate 3 may be surrounded entirely by the extruded heat sink 1 and the metal case 2, or only the portion of the substrate 3 that includes noise sources such as the DCDC converter and the control unit may be surrounded by the extruded heat sink 1 and the metal case 2.

[0019] 2 is a cross-sectional view showing the configuration of an automotive lamp equipped with the automotive lighting control device 100. The automotive lamp includes a housing 5, a transparent member 6, and an LED (Light Emitting Diode) optical unit 7. The housing 5 and the transparent member 6 form an enclosed space, and the automotive lighting control device 100 and the LED optical unit 7 are provided within the enclosed space.

[0020] The in-vehicle lighting control device 100 is screwed into a housing 5 with screws 4. The extruded heat sink 1 of the in-vehicle lighting control device 100 does not have any screw holes, and the screws 4 screw the metal case 2 and substrate 3 of the in-vehicle lighting control device 100 into the housing 5 together.

[0021] The vehicle-side cord 8 electrically connects the in-vehicle lighting control device 100 to vehicle equipment (not shown) including, for example, the vehicle's ECU and battery. The cord 9 electrically connects the in-vehicle lighting control device 100 to the LED optical unit 7, and when voltage is applied to the vehicle-side cord 8, the in-vehicle lighting control device 100 is able to turn on the LED optical unit 7.

[0022] 3 and 4 are cross-sectional views of the in-vehicle lighting control device 100 taken along lines AA and BB in FIG. 1, respectively.

[0023] 1 and 3, the metal case 2 has a plurality of (four in FIG. 1) raised portions 2a protruding upward from the side walls of the metal case 2. The raised portions 2a have U-shaped notches, and the portions surrounded by the notches are bent to provide snap-fit ​​portions 2b as elastic mating portions. In the example of FIG. 3, the left and right snap-fit ​​portions 2b are mated with both ends of the extruded material heat sink 1, respectively.

[0024] 1 and 4, the metal case 2 has a plurality of bent portions 2c formed by bending the upper portions of the side walls of the metal case 2 toward the space within the metal case 2. The substrate 3 is placed on the bent portions 2c. The substrate 3 and the extruded heat sink 1 are sandwiched between the bent portions 2c in Fig. 4 and the snap-fit ​​portions 2b in Fig. 3, thereby restricting the movement of the substrate 3 and the extruded heat sink 1 in the vertical direction.

[0025] The substrate 3 and the metal case 2 are electrically connected by contacting and electrically connecting the substrate 3 with the bent portion 2c in Figure 4, and therefore the substrate 3 is electrically connected to the vehicle body earth via the metal case 2. The electrical connection between the metal case 2 and the vehicle body earth can be achieved using a configuration similar to that of the conventional configuration. For example, in Figure 2, the metal case 2 may be screwed into the housing 5 with screws 4, so that the metal case 2 is screwed and electrically connected to a metal part that serves as the vehicle body earth via the screws 4 and the housing 5. Also, for example, the vehicle-side cord 8 may include a line at the same potential as the vehicle body earth, and the line may be screwed into the metal case 2 with the screws 4, so that the metal case 2 is electrically connected to the vehicle body earth.

[0026] The assembly of the automotive lighting control device 100 will now be described. After placing the substrate 3 on the bent portion 2c of the metal case 2, the extruded heat sink 1 is pushed in from above as shown in Figures 3 and 4. This causes the snap-fit ​​portion 2b to bend outward as shown in Figure 3, while the extruded heat sink 1 moves downward. When the seating surface 1a of the extruded heat sink 1 for receiving the substrate 3 comes into contact with the substrate 3, the snap-fit ​​portion 2b elastically returns to the inside as shown in Figure 3, thereby fitting with the extruded heat sink 1.

[0027] The bent portion 2c of the metal case 2 is thermally connected to the substrate 3, and thus the metal case 2 dissipates heat from the substrate 3 to the outside. In the first embodiment, the substrate 3 includes an electronic component 10 that is thermally connected to the metal case 2 via a heat dissipation material 12, and the metal case 2 is also able to dissipate heat from the electronic component 10 to the outside.

[0028] Furthermore, since the seating surface 1a of the extruded heat sink 1 is thermally connected to the substrate 3, the extruded heat sink 1 dissipates heat from the substrate 3 to the outside. In the first embodiment, the substrate 3 includes an electronic component 11 thermally connected to the extruded heat sink 1 via a heat dissipation material 12, and the extruded heat sink 1 is also able to dissipate heat from the electronic component 11 to the outside. The above-mentioned DC-DC converter and control unit may be electronic components 10, 11, or may be electronic components that are not in contact with the heat dissipation material 12.

[0029] If the thickness of the snap-fit ​​portion 2b is greater than 0.8 mm, the rigidity will be too high and it will be difficult to obtain appropriate elasticity. Therefore, in order to achieve both elasticity and mechanical strength in the snap-fit ​​portion 2b, it is preferable that the snap-fit ​​portion 2b include a plate portion having a thickness of 0.8 mm or less.

[0030] In the first embodiment, the heat sink is an extruded heat sink 1. Although the extruded heat sink 1 is relatively inexpensive, it is difficult to form screw holes in it during the manufacturing process. In contrast, in the first embodiment, the substrate 3 is surrounded by the extruded heat sink 1 and the metal case 2, and the snap-fit ​​portion 2b of the metal case 2 fits into the heat sink. Therefore, there is no need to provide screw holes in the heat sink for screwing the heat sink to the metal case 2, and the extruded heat sink 1 can be used as the heat sink.

[0031] Next, a description will be given of the heat dissipation path in the automotive lighting control device 100 according to Embodiment 1. Heat generated from the substrate 3 is transferred by the heat dissipation material 12 to the extruded material heat sink 1 and the metal case 2, to the seating surface 1a of the extruded material heat sink 1, or to the bent portion 2c of the metal case 2, and is thereby dissipated to the outside of the automotive lighting control device 100. This is effective in the automotive lighting control device 100 of Fig. 2, but may also be applied to automotive control devices other than the automotive lighting control device 100.

[0032] On the other hand, extruded heat sinks tend to have lower thermal emissivity, i.e., lower heat dissipation performance, than other types of heat sinks. Therefore, in the first embodiment, the extruded heat sink 1 is anodized to improve the heat dissipation performance of the extruded heat sink 1. Note that, with regard to heat, "emissivity + reflectivity = 1" holds true, and the thermal emissivity of the extruded heat sink 1 after anodizing is, for example, about 0.85.

[0033] Next, the conduction path in the automotive lighting control device 100 according to the first embodiment will be described. If the entire surface of the extruded heat sink 1 is anodized, an insulating film will be formed on the extruded heat sink 1, which will prevent electrical continuity between the extruded heat sink 1 and the substrate 3, and therefore between the extruded heat sink 1 and the metal case 2. In this case, the extruded heat sink 1 and the metal case 2 will not be able to adequately shield high-frequency radiation noise. Therefore, in the first embodiment, the extruded heat sink 1 is anodized except for the portion that is electrically connected to the substrate 3. For example, the insulating film formed by the anodization is removed from the seating surface 1a of the extruded heat sink 1 that comes into contact with the substrate 3, thereby ensuring a conduction path.

[0034] As a result, the extruded heat sink 1 is electrically connected via the seating surface 1a to the earth provided on the upper side of the substrate 3 in Fig. 3. Although not shown, an earth is also provided on the lower side of the substrate 3, which is electrically connected to the bent portion 2c of the metal case 2, and the upper and lower earths are electrically connected via pattern wiring or through holes.

[0035] In the first embodiment configured as described above, the extruded heat sink 1 is pushed in from above and fixed at the snap-fit ​​portion 2b, whereby the substrate 3 is sandwiched between the extruded heat sink 1 and the metal case 2. At this time, the seating surface 1a of the extruded heat sink 1 and the substrate 3 are electrically connected, and the substrate 3 and the bent portion 2c of the metal case 2 are electrically connected, so that the metal case 2 is electrically connected to the extruded heat sink 1 via the substrate 3. The ground of the substrate 3 is electrically connected to the vehicle body ground, and as described above, the metal case 2 is electrically connected to the vehicle body ground. Therefore, in the first embodiment, the extruded heat sink 1 and the metal case 2 can obtain the ability to shield high-frequency radiation noise.

[0036] According to the in-vehicle control device of the first embodiment, the metal case that cooperates with the heat sink to surround the board has a fitting portion that fits with the heat sink. With this configuration, the heat sink, the metal case, and the board can be fixed together without providing screw holes in the heat sink.

[0037] The contents of the embodiments can be modified or omitted as appropriate.

[0038] The above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned.

[0039] 1 Extruded heat sink, 2 Metal case, 2b Snap fit portion, 2c Bending portion, 3 Substrate, 100 In-vehicle lighting control device.

Claims

1. A circuit board including a DC-DC converter that boosts or decompresses the voltage supplied from the battery, and a control unit that switches the DC-DC converter at a frequency higher than the AM band, An extruded heat sink, which is thermally connected to the substrate, releases heat from the substrate to the outside. A metal case that surrounds the substrate in cooperation with the extruded heat sink, the metal case having a fitting portion that fits with the extruded heat sink. An in-vehicle control device equipped with the following features.

2. An in-vehicle control device according to claim 1, The extruded heat sink is electrically connected to the substrate, An in-vehicle control device, wherein the metal case is electrically connected to the extruded heat sink via the substrate.

3. An in-vehicle control device according to claim 2, An in-vehicle control device, wherein the extruded heat sink is anodized, except for the portion that is electrically connected to the substrate.

4. An in-vehicle control device according to claim 1, The aforementioned in-vehicle control device is an in-vehicle lighting control device, an in-vehicle control device.

5. An in-vehicle control device according to claim 1, The aforementioned fitting portion includes a plate portion with a thickness of 0.8 mm or less, and is an in-vehicle control device.

6. An in-vehicle control device according to claim 1, The aforementioned metal case is An in-vehicle control device further having a bent portion that sandwiches the substrate and the extruded heat sink between itself and the fitting portion.