Vehicle Power Supply Box

Abstract

To provide a vehicular power source box that can appropriately release heat while avoiding a weight increase.SOLUTION: A vehicular power source box 1 includes: a substrate that is mounted with a component accompanied by heat generation by supplying power source output; and a heat sink 13 that releases heat of the component by thermally contacting with the component on the substrate. The heat sink 13 is formed of a resin and has a surface to which metal plating is applied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a power supply box for a vehicle. [Background technology]

[0002] In a vehicle, the power output of the battery and alternator, which serve as the main power source, must be supplied to various loads such as various electrical devices (including the ECU) via a wiring harness. It is also necessary to distribute the power output of the main power source into multiple systems, control the on / off of the power supply for each system, and protect each part of the circuit from abnormalities such as overcurrent. For this reason, a device called a junction box, fuse box, or power supply box is typically installed between the main power source and the various loads.

[0003] The term junction box is often used when distributing power to multiple systems. The term fuse box is often used when storing fuses or fusible links that cut off circuits in the event of an abnormality such as an overcurrent. The term power supply box is often used when storing relays and having switching functions in addition to the functions of a junction box or fuse box. Patent Document 1 below discloses a power supply box. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-72764 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the amount of electrical equipment installed in vehicles has increased, leading to an increase in the number of components housed in power supply boxes. At the same time, the power consumption of each electrical device has also increased, resulting in a corresponding increase in the amount of heat generated by the components inside the power supply box. As a result, the heat generated by the power supply box tends to increase, requiring appropriate heat dissipation. Metal heat sinks made of extruded aluminum and other materials are used to dissipate heat, but increasing the heat dissipation rate increases the volume of the heat sink, which in turn increases the weight of the power supply box. In recent years, from an environmental perspective, there has been a strong demand for reducing carbon dioxide emissions from vehicles, i.e., improving fuel efficiency. Improving fuel efficiency requires reducing the total weight of the vehicle, and there is a strong demand for weight reduction in various equipment installed in the vehicle. Therefore, the weight increase of the power supply box cannot be ignored.

[0006] An object of the present invention is to provide a power supply box for a vehicle that is capable of adequately dissipating heat while avoiding an increase in weight. [Means for solving the problem]

[0007] The vehicle power supply box of the present invention comprises a board on which components that generate heat when power output is supplied are mounted, and a heat sink that is in thermal contact with the components on the board and dissipates heat from the components, the heat sink being formed from resin and having a metal plated surface. [Effects of the Invention]

[0008] The vehicle power supply box according to the present invention can perform appropriate heat dissipation while avoiding an increase in weight. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram of a vehicle equipped with a vehicle power supply box according to an embodiment; [Figure 2] FIG. 2 is a perspective view showing the front of the power supply box. [Figure 3] FIG. 2 is an exploded perspective view showing the front of the power supply box. [Figure 4]FIG. 2 is a perspective view showing the rear surface of the power supply box. [Figure 5] FIG. 2 is a front view of the circuit board housed in the power supply box. [Figure 6] FIG. 2 is a bottom view of the power supply box. [Figure 7] FIG. 2 is a perspective view of a fuse attached to a fuse connector of the power supply box. DETAILED DESCRIPTION OF THE INVENTION

[0010] The vehicle power supply box 1 according to the embodiment will be described in detail below with reference to the drawings. Note that the terms "up, down, left, right" in the following description refer to the up, down, left, right, and right of the drawings for the purpose of explanation, and do not limit the orientation in which the power supply box 1 is installed.

[0011] As shown in the block diagram of FIG. 1, the power supply box 1 is electrically connected to a battery 2, which serves as the vehicle's main power source, more specifically, via a wire harness 4. Although not shown in FIG. 1, the power supply box 1 is also electrically connected to an alternator, which serves as the main power source. The power supply box 1 is also supplied with power outputs from the battery 2 and the alternator. The power supply box 1 is also electrically connected via the wire harness 4 to a plurality of loads 3, which are various electrical devices mounted on the vehicle. The loads 3 include electronic units 3a such as ECUs that control the various electrical devices. For example, loads 3 that consume a lot of power include air conditioning equipment, heaters built into the rear window, mirrors, seats, steering wheel, etc., and headlamps.

[0012] The power supply box 1 has the function of distributing the supplied power output to each load 3. This power distribution allows the use of wire harnesses 4 with wire diameters that are appropriate for the current required by each load 3. In other words, the magnitude of the current flowing through the power supply box 1 is significantly greater than the magnitude of the current flowing through each load 3, resulting in a significant amount of heat generation from the power supply box 1. Furthermore, if a circuit short occurs during power distribution, an overcurrent may occur, potentially damaging the wire harness 4 and electrical equipment. The power supply box 1 is connected to the loads 3 on the circuit that may be subject to such a short circuit by the wire harness 4 via fuses or fusible links. In the event of an overcurrent, these fuses or fusible links interrupt the current, thereby protecting the wire harness 4 and electrical equipment. Hereinafter, interrupting components such as fuses and fusible links will be collectively referred to as fuses. In this embodiment, a so-called blade fuse 20 (hereinafter simply referred to as fuse 20) shown in FIG. 7 is attached to a fuse connector 15 (described later) of the power supply box 1.

[0013] Furthermore, the power supply box 1 switches on / off the load 3 using a relay 18 (see Figure 5). For example, if the load 3 is the air conditioning equipment described above, when a vehicle occupant turns on the air conditioning switch, the relay 18 opens the circuit and power is supplied to the air conditioning equipment, which is the load 3. Of course, there are also loads 3 for which the on / off of the relay 18 is automatically controlled based on the detection results of a sensor, rather than by the operation of the occupant. Fuses 20 are stored in a consolidated manner in the fuse connector 15 of the power supply box 1. For this reason, if the power supply is cut off by a fuse 20, the fuse 20 that cut off the power supply can be found in the fuse connector 15 where the fuses 20 are consolidated, and replaced, which also improves the maintainability of the power supply box 1.

[0014] Next, the configuration of the power supply box 1 of this embodiment will be described with reference to FIGS. 2 to 5. The power supply box 1 includes a circuit board 10 mounted with a fuse 20 and a relay 18 inside its housing 11. The housing 11 is composed of a first half-housing 11a made of resin that covers one side of the circuit board 10, and a second half-housing 11b made of resin that covers the other side of the circuit board 10. The circuit board 10 is fixed to the second half-housing 11b with screws or the like, and the first half-housing 11a is attached to the second half-housing 11b so that the circuit board 10 is sandwiched between the first half-housing 11a and the second half-housing 11b. The circuit board 10 is protected by the housing 11 from external forces, dust, water, and the like.

[0015] In this embodiment, the relay 18 is a component that generates heat when supplied with power output from a main power source such as a battery 2. The power supply box 1 also includes a heat sink 13 that is in thermal contact with the relay 18 on the circuit board 10 and dissipates heat from the relay 18. The term "thermal contact" used here refers to contact such that heat from the relay 18, which is a heat-generating component, is conducted to the heat sink 13. In other words, the "thermal contact" state used here refers to a state in which the two are in direct physical contact, or a state in which the two are in contact via a heat dissipation sheet or thermally conductive grease. In this embodiment, an opening 12 that exposes the heat sink 13 is formed in the first half housing 11a so as not to impede heat dissipation from the relay 18, which is in thermal contact with the heat-generating component, and the heat sink 13.

[0016] In addition to the bus bars 17 and relays 18 described above, the board 10 also has an input connector 14, a fuse connector 15, and an output connector 16. The connection ports of the input connector 14, the fuse connector 15, and the output connector 16 are exposed on the side of the housing 11 when the board 10 is housed in the housing 11.

[0017] The input connector 14 is a connector into which the power output of a main power source such as a battery 2 is input, and three input connectors 14 are provided in this embodiment. The two input connectors 14 other than the input connector 14 at the bottom left in FIG. 5 are provided as a single connector housing. The fuse connector 15 is a connector to which a plurality of fuses 20 are attached, as shown in FIG. 6. In this embodiment, the single input connector 14 at the bottom left in FIG. 5 and the fuse connector 15 are provided as a single connector housing. The output connector 16 is a connector that outputs power to the load 3, and five output connectors 16 are provided in this embodiment. The two output connectors 16 on the left side in FIG. 5 are provided as a single connector housing.

[0018] A plurality of bus bars 17 are provided on the substrate 10 along the fuse connector 15. A fitting portion 19 is formed on the bottom surface of the fuse connector 15, to which a plurality of fuses 20 are attached, as shown in Fig. 6. A power output input to the input connector 14 at the lower left in Fig. 5 is distributed and passed through fuses 20 in the fuse connector 15 having a capacity according to the output destination load 3, the bus bars 17, and relays 18, before being output from the output connector 16 at the upper right in Fig. 5. The wire harness 4 connected to the output connector 16 at the upper right is branched and connected to the output destination load 3.

[0019] The relays 18 in this embodiment are sealed relays in the form of a box-shaped resin package, and multiple relays 18 are mounted in the center of the substrate 10. In this embodiment, twenty relays 18 are provided, and nineteen relays 18, excluding the one relay 18 at the bottom right in FIG. 5, face the opening 12 and are in thermal contact with the heat sink 13. Power output input to two input connectors 14 other than the one at the bottom left in FIG. 5, is distributed and output to output connectors 16 through relays 18 according to the destination loads 3. Wire harnesses 4 connected to the multiple output connectors 16 are each connected to the destination loads 3 directly or after being appropriately branched.

[0020] The heat sink 13 of this embodiment is made of resin and has numerous heat dissipation fins on its surface to increase the heat dissipation area. The heat sink 13 is fitted into the opening 12 formed in the first half housing 11a, and its back surface is in thermal contact with the top surface of the resin package of the nineteen relays 18. As described above, the power supply box 1 to which power output is supplied generates a large amount of heat, and considering this heat dissipation, the surface area, i.e., the volume, of the heat sink 13 is unavoidably large. However, because the heat sink 13 of this embodiment is made of resin, it is lighter than a metal heat sink and contributes significantly to reducing the vehicle's weight. As a result, the power supply box 1 of this embodiment, as described above, contributes significantly to reducing carbon dioxide emissions by reducing the vehicle's weight, i.e., improving fuel efficiency.

[0021] Furthermore, the power supply box 1 of this embodiment is fixed to the vehicle body via a bracket, but if it has a large metal heat sink, it will be subject to severe vibrations, and the bracket will need to be reinforced. If a new reinforced bracket is required, it will be costly and the weight will increase by the amount of reinforcement required. However, the power supply box 1 of this embodiment can avoid such increased costs and weight.

[0022] Here, a resin heat sink 13 has a lower thermal conductivity than a metal heat sink. For this reason, the heat sink 13 in this embodiment has a metal plating layer formed on its surface to improve its thermal conductivity. The reduced thermal conductivity of the resin heat sink 13 can be compensated for by forming the metal plating layer. Furthermore, the metal plating layer not only improves thermal conductivity, but also improves heat dissipation performance because it is formed on the surface of the heat sink 13, which is suitable for heat dissipation. Furthermore, while metal heat sinks are formed using die-cast or extruded materials, a resin heat sink 13 has a lower manufacturing cost even when a metal plating layer is formed on its surface, allowing for reduced manufacturing costs. The weight increase of the heat sink 13 due to the formation of the metal plating layer is minimal.

[0023] Furthermore, if multiple relays 18 are provided inside the power supply box 1 as in this embodiment, there is a risk that the heat generated by adjacent relays 18 will interfere with each other, causing an overall temperature rise. However, in this embodiment, the heat sink 13 can lower the temperature of each relay 18, thereby suppressing heat generation due to thermal interference and allowing the temperature of the entire power supply box 1 to be lowered.

[0024] In recent years, the number of electrical systems installed in vehicles has increased, and it is not uncommon for semiconductor components to be mounted on the board 10 of the power supply box 1. To reduce equipment costs, it is desirable to solder relays 18, semiconductor components, and other components to the board 10 using only the reflow process. However, in this case, the hot air generated during reflow may cause the air inside the sealed relay 18 of this embodiment to expand, potentially damaging the hermeticity of the package. Changing the relay 18 from a sealed package to a non-sealed package is also an option, but this would increase costs. Therefore, if the reflow process is performed in a state where the heat sink 13 is in thermal contact with the relay 18 having a metal plating layer, allowing the heat from the relay 18 to be dissipated, it is possible to reflow the sealed packaged relay 18.

[0025] Because the power supply box 1 of this embodiment is mounted on a vehicle, it is anticipated that the environment in which the vehicle is located may fall below freezing. If the ambient temperature falls below freezing, the contacts of the relay 18 inside the power supply box 1 may freeze and cease to conduct. Freezing is accelerated by so-called "heat sink," in which heat is removed from the relay 18 through the wiring on the circuit board 10 and the connected wire harness 4. In particular, the power supply box 1 has a thick wire harness 4 that supplies power output, so heat is easily removed by "heat sink." If the contacts of the relay 18 are cooled by "heat sink" even though the temperature inside the power supply box 1 is high, condensation occurs due to the temperature difference, making freezing more likely. Therefore, providing a heat sink 13 reduces the temperature difference between the ambient temperature and the contacts inside the relay 18, thereby preventing freezing.

[0026] In this embodiment, the component that generates heat due to the power output and is in thermal contact with the heat sink 13 is the relay 18, but such a component is not limited to the relay 18. There are also fuses in the form of box-shaped resin packages, and semiconductor components that generate heat. These components can also be components that generate heat due to the power output and are in thermal contact with the heat sink 13.

[0027] The vehicle power supply box 1 of the above embodiment is provided with a heat sink 13 that is in thermal contact with a component (relay 18) that generates heat when power output (such as the battery 2) is supplied and is mounted on the circuit board 10, thereby dissipating heat from the component (relay 18). The heat sink 13 is made of resin, and its surface is metal-plated. Because the heat sink 13 is made of resin, an increase in weight of the power supply box 1 can be prevented, and because a metal-plated layer is formed on the surface of the heat sink 13, the thermal conductivity of the resin heat sink 13 can be improved. In other words, the vehicle power supply box 1 of this embodiment enables appropriate heat dissipation while avoiding an increase in weight.

[0028] The vehicle power supply box 1 of the above embodiment further includes a housing 11 that houses the circuit board 10. The housing 11 is composed of a first half-housing 11a that covers one side of the circuit board 10 and a second half-housing 11b that covers the other side of the circuit board 10. An opening 12 that exposes the heat sink 13 is formed in one of the first and second half-housings 11a, 11b (the first half-housing 11a in the above embodiment). This allows the housing 11 to protect the circuit board 10 and the components mounted on the circuit board 10 (such as the bus bar 17 and the relay 18) from external forces, dust, water, and the like. Furthermore, to prevent heat generated by the components from accumulating within the housing 11, the opening 12 is formed in one of the first and second half-housings 11a, 11b to expose the heat sink 13, thereby ensuring reliable heat dissipation by the heat sink 13.

[0029] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0030] 1 (vehicle) power box 2 Battery (main power source) 3. Load 10 Substrate 11. Housing 11a First half housing 11b Second half housing 12 Opening 13 Heat sink 18 Relay (parts that generate heat due to power output)

Claims

1. A power supply box for a vehicle, a circuit board on which components that generate heat when supplied with power output are mounted; a heat sink that is in thermal contact with the component on the board and dissipates heat from the component; an input connector mounted on the board for inputting the power output to the board; an output connector mounted on the board for outputting power from the board to a load electrically connected to the vehicle power supply box, the component is a relay that switches between the input connector and the output connector; the relay is mounted at the center of the board, and the input connector and the output connector are mounted on the peripheral edge of the board around the relay, The heat sink is formed from resin and has a metal-plated surface.

2. The substrate further includes a housing for receiving the substrate. the housing is composed of a first half housing covering one side of the substrate and a second half housing covering the other side of the substrate, 2. The vehicle power supply box according to claim 1, wherein one of the first and second half housings has an opening through which the heat sink is exposed.

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