JP7637236B2 - In-vehicle electronic control device - Google Patents

Description

The present invention relates to an electronic control device for an automobile.

Generally, vehicles such as automobiles are equipped with multiple electronic control units (ECUs) to control various objects including the engine, power steering, brakes, airbags, etc. An electronic control unit installed in a vehicle (hereinafter also referred to as an "on-vehicle electronic control unit") has a structure in which a circuit board on which electronic components are mounted is housed inside a housing (see, for example, Patent Document 1).

JP 2016-141173 A

Generally, automotive electronic control devices are often installed in the engine compartment. However, in recent years, more and more automotive electronic control devices are being installed in vehicles in order to realize safe driving assistance and autonomous driving. In addition, automotive electronic control devices may be installed inside the passenger compartment in addition to the engine compartment.

However, when an on-board electronic control device is installed inside the vehicle cabin, there is a risk that the driver may accidentally hit the on-board electronic control device with his or her hands or feet. If the housing of the on-board electronic control device is damaged by such an external impact, this could impair the safety of driving assistance or autonomous driving.

The object of the present invention is to provide an in-vehicle electronic control device that can contribute to safer driving assistance and autonomous driving.

In order to solve the above problems, for example, the configurations described in the claims are adopted.
The present application includes multiple means for solving the above problems, one of which is an in-vehicle electronic control device comprising a circuit board on which electronic components are mounted, a first housing that houses the circuit board, and a second housing that houses the first housing.

The present invention can contribute to safer driving assistance and automated driving.
Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments.

1 is a perspective view of an in-vehicle electronic control device according to a first embodiment, as viewed from an oblique direction; 2 is a cross-sectional view of the on-vehicle electronic control device shown in FIG. 1 along the line AA. 2 is a cross-sectional view of the on-vehicle electronic control device shown in FIG. 1 along the line B-B. FIG. 13 is a diagram showing an example in which the ventilation holes are formed in a circular shape. 11 is a perspective view of an on-vehicle electronic control device according to a comparative embodiment, as viewed obliquely. FIG. 3A and 3B are diagrams illustrating an air flow achieved by the in-vehicle electronic control device according to the first embodiment. FIG. 13 is a diagram showing an example in which the ventilation holes are formed in a rectangular shape. FIG. 13 is a diagram showing an example in which the ventilation holes are formed in a triangular shape. FIG. 13 is a diagram showing an example in which the ventilation holes are formed in a pentagonal shape. FIG. 4 is a diagram illustrating a first modified example of the in-vehicle electronic control device according to the first embodiment. FIG. 11 is a diagram illustrating a second modified example of the in-vehicle electronic control device according to the first embodiment. FIG. 11 is a perspective view of an on-vehicle electronic control device according to a second embodiment, as viewed from an oblique direction. 13 is a cross-sectional view of the in-vehicle electronic control device shown in FIG. 12 along the line CC. 13 is a cross-sectional view of the in-vehicle electronic control device shown in FIG. 12 along the line D-D. FIG. 13 is a diagram illustrating a first modified example of the in-vehicle electronic control device according to the second embodiment. FIG. 13 is a diagram illustrating a second modified example of the in-vehicle electronic control device according to the second embodiment. FIG. 11 is a perspective view of an on-vehicle electronic control device according to a third embodiment, as viewed from an oblique direction. 13 is a diagram illustrating a modified example of the in-vehicle electronic control device according to the third embodiment. FIG. FIG. 11 is a cross-sectional view showing an on-vehicle electronic control device according to a fourth embodiment. FIG. 13 is a perspective view of an on-vehicle electronic control device according to a fifth embodiment, as viewed from an oblique direction. FIG. 13 is a perspective view of an in-vehicle electronic control device according to a sixth embodiment, as viewed from an oblique direction.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this specification and the drawings, elements having substantially the same functions or configurations are designated by the same reference numerals, and duplicated descriptions will be omitted.

First Embodiment
Fig. 1 is a perspective view of an on-vehicle electronic control device according to the first embodiment, seen from an oblique direction. Fig. 2 is a cross-sectional view of the on-vehicle electronic control device shown in Fig. 1 taken along line A-A, and Fig. 3 is a cross-sectional view of the on-vehicle electronic control device shown in Fig. 1 taken along line B-B. The on-vehicle electronic control device is not limited to electronic control devices mounted on vehicles that run on liquid fuel such as gasoline or diesel, and can be widely applied to electronic control devices mounted on vehicles that run on hydrogen as fuel, hybrid vehicles, electric vehicles, and the like. Furthermore, the object controlled by the on-vehicle electronic control device is not limited to a specific object.

In the following explanation, in order to clarify the shape and positional relationship of each part of the in-vehicle electronic control device, the thickness direction (height direction) of the in-vehicle electronic control device is defined as the Z direction, and one of the two axial directions perpendicular to the Z direction is defined as the X direction, and the other direction is defined as the Y direction. The X direction, Y direction, and Z direction are perpendicular to each other.

As shown in Figures 1 to 3, the in-vehicle electronic control device 100 of the first embodiment comprises a circuit board 10, an inner case 11 that houses the circuit board 10, and an outer case 12 that houses the inner case 11.

(Circuit board 10)
The circuit board 10 is formed of, for example, a printed wiring board, which is a rigid board using a glass epoxy resin as a base material. The circuit board 10 may have a wiring pattern formed on only one side, or may have a wiring pattern formed on both sides. The circuit board 10 is a board that is rectangular (rectangular or square) when viewed from the Z direction. Heat generating components 15 and connector components 16 are mounted on the circuit board 10 as examples of electronic components. In addition to the heat generating components 15 and connector components 16, electronic components such as switching elements, resistive elements, capacitors, and diodes (not shown) are also mounted on the circuit board 10. The heat generating components 15 and connector components 16 are mounted on the circuit board 10, with one board surface 10A of the circuit board 10 being used as a common mounting surface. That is, the heat generating components 15 and connector components 16 are mounted on the same surface of the circuit board 10. The heat generating components 15 and connector components 16 are also electrically connected to each other via a wiring pattern (not shown) formed on the board surface 10A of the circuit board 10.

The heat-generating component 15 is an electronic component that has a built-in arithmetic circuit such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit), which is called a microcomputer. The heat-generating component 15 is a highly functional component that has a processor such as an IC (integrated circuit) chip or a semiconductor chip, and operates at a processing speed of several hundred MHz to several GHz. Such highly functional components generate a lot of heat in order to perform arithmetic processing at high speed. In other words, the heat-generating component 15 is an electronic component that generates heat. In addition to the heat-generating component 15, other electronic components (e.g., diodes, etc.) are mounted on the circuit board 10, but the amount of heat generated is largely electronic components with arithmetic functions. For this reason, in this specification, electronic components with arithmetic functions are defined as heat-generating components. The heat-generating component 15 is not limited to what is called a microcomputer, and may be, for example, a memory that communicates with a microcomputer. The heat-generating component 15, which is a highly functional component, all has very high power consumption, sometimes reaching tens of watts.

The heat-generating components 15 are surface-mounted electronic components. The heat-generating components 15 are arranged on one side of the circuit board 10 in the Y direction (the left side in FIG. 3). In this embodiment, as an example, two heat-generating components 15 are mounted on one circuit board 10. The two heat-generating components 15 are arranged at a predetermined interval in the X direction. The number of heat-generating components 15 mounted on the circuit board 10 may be one or three or more.

The connector part 16 is disposed on the other side of the circuit board 10 in the Y direction (the right side in FIG. 3). Specifically, the connector part 16 is mounted on the end of the circuit board 10, which is the side opposite to the side on which the heat generating part 15 is mounted in the Y direction. The connector part 16 is a connector part for transmitting an electric signal generated by the circuit board 10 to an external device, and for receiving an electric signal generated by the external device by the circuit board 10. Examples of the external device that exchanges electric signals with the in-vehicle electronic control device 100 include an in-vehicle electronic control device other than the in-vehicle electronic control device 100, a camera, a sensor, an actuator, and the like. A harness (not shown) is connected to the connector part 16. The harness is a bundle of wiring for electrically connecting the circuit board 10 and the external device. The harness has a structure in which a metal wire, which is a conductor for making an electrical connection, is covered with a protective coating, which is an insulator. The harness is drawn out to the outside of the outer case 12 through a drawing part (not shown) provided in the outer case 12. Therefore, the connector part 16 has a function of releasing heat to the outside of the outer case 12 via the harness. In this embodiment, as an example, two connector parts 16 are mounted on one circuit board 10. The two connector parts 16 are arranged at a predetermined interval in the X direction. The number of connector parts 16 mounted on the circuit board 10 may be one, or three or more.

(Inner case 11)
The inner case 11 is a hollow case having a first space 21 therein capable of accommodating the circuit board 10. The inner case 11 corresponds to a first housing. The inner case 11 is a polyhedron, more specifically a hexahedron (rectangular parallelepiped). The inner case 11 is preferably a metal case. The metal constituting the inner case 11 is preferably aluminum or an alloy mainly made of aluminum. However, the material constituting the inner case 11 is not limited to metal, and may be resin. Also, a part of the inner case 11 may be made of metal, and the other part may be made of resin.

The inner case 11 is mainly composed of an inner case body 22 and an inner case lid 23. The inner case body 22 is a structure with a U-shaped cross section that opens on one side in the Z direction (the upper side in Figures 2 and 3). The inner case lid 23 is a plate-shaped structure with an outer dimension larger than the opening dimension of the inner case body 22. The above-mentioned first space 21 is a substantially sealed space by closing the opening of the inner case body 22 with the inner case lid 23. The inner case body 22 and the inner case lid 23 are connected by, for example, screws not shown. A stepped portion 24 is formed on the inside of the inner case body 22. The circuit board 10 is attached to the inner case body 22 by, for example, screws not shown, with the circuit board 10 placed on the stepped portion 24. In addition, the circuit board 10 is arranged so that one board surface 10A faces the inner case lid 23.

The inner case 11 is supported in the first space 21 of the inner case 11 by a plurality of brackets 30. In this embodiment, as an example, the inner case 11 is supported by four brackets 30. The four brackets 30 are arranged to sandwich the inner case 11 in the X direction. Each bracket 30 is formed in an L shape. As shown in FIG. 2, the bracket 30 has a first mounting piece 31 and a second mounting piece 32 integrally. The first mounting piece 31 is fixedly attached to the inner bottom surface of the outer case 12. The second mounting piece 32 is fixedly attached to the side of the inner case main body 22. In this manner, when the inner case 11 is attached to the outer case 12 using a plurality of brackets 30, a gap is formed between the outer surface of the inner case 11 and the inner surface of the outer case 12. This gap is formed around the entire circumference of the inner case 11, which is a polyhedron.

(Outer case 12)
The outer case 12 is a hollow case having a second space 25 inside that can accommodate the inner case 11. The outer case 12 corresponds to a second housing. The outer case 12 is a polyhedron, more specifically, a hexahedron (rectangular parallelepiped). The outer case 12 is arranged so as to surround the entire surface of the inner case 11, which is a polyhedron. As a result, the inner case 11 is mechanically protected by the outer case 12. The outer case 12 is preferably a metal case. The metal constituting the outer case 12 is preferably aluminum or an alloy mainly made of aluminum. However, the material constituting the outer case 12 is not limited to metal, and may be resin. Also, a part of the outer case 12 may be made of metal, and the other part may be made of resin.

The outer case 12 is mainly composed of an outer case body 26 and an outer case lid 27. The outer case body 26 is a structure with a U-shaped cross section that is open on one side in the Z direction (the upper side in Figures 2 and 3). The outer case lid 27 is a plate-like structure with external dimensions larger than the opening dimensions of the outer case body 26. The above-mentioned second space 25 is a substantially sealed space by closing the opening of the outer case body 26 with the outer case lid 27. The outer case body 26 and the outer case lid 27 are joined together, for example, by screws (not shown).

In this embodiment, as an example, assuming that the in-vehicle electronic control device 100 is mounted on the vehicle in the orientation (posture) shown in Figures 2 and 3, the six faces of the outer case 12 are defined as follows. First, the face facing one side of the Z direction is the upper face 12A, and the face facing the other side of the Z direction is the lower face 12B. The four faces facing the X direction and the Y direction are side faces 12C, 12D, 12E, and 12F, respectively. The area of the upper face 12A is larger than the area of each of the side faces 12C, 12D, 12E, and 12F, and is the same as the area of the lower face 12B. The in-vehicle electronic control device 100 can also be mounted on the vehicle with the two opposing side faces of the outer case 12 facing up and down. The in-vehicle electronic control device 100 can also be mounted on the vehicle in an oblique posture with respect to the horizontal plane.

The outer case 12 is provided with communication parts 35 and 36. The communication part 35 is a part that communicates between the outside and the inside of the outer case 12, and the communication part 36 is also a part that communicates between the outside and the inside of the outer case 12. Communication means spatial connection. In other words, the communication parts 35 and 36 are parts that connect the space outside the outer case 12 and the space inside the outer case 12 (the second space 25). It is preferable that the communication parts 35 and 36 are provided in at least two places on the outer case 12 so that air can be exchanged between the space outside the outer case 12 and the space inside the outer case 12. In addition, it is preferable that the two places where the communication parts 35 and 36 are provided are located at places away from each other so that air can be exchanged more smoothly between the space outside the outer case 12 and the space inside the outer case 12.

In this embodiment, as an example, communication parts 35, 36 are provided at two locations on the outer case 12. Specifically, communication part 35 is provided on side 12E of the outer case 12, and communication part 36 is provided on side 12F of the outer case 12, so that the two locations where communication parts 35, 36 are provided are located at locations separated from each other. Side 12E and side 12F are located at locations separated from each other, so that one is the air inflow side and the other is the air outflow side. Furthermore, side 12E and side 12F are arranged facing each other in the Y direction.

1 and 3, the communication portion 35 provided on the side surface 12E is provided at a position closer to the heat generating component 15 than the connector component 16. In contrast, the communication portion 36 provided on the side surface 12F is provided at a position closer to the connector component 16 than the heat generating component 15. The communication portion 35 is composed of a plurality of ventilation holes 35a, and the communication portion 36 is composed of a plurality of ventilation holes 36A. The plurality of ventilation holes 35A are densely arranged in a matrix-like arrangement, and the plurality of ventilation holes 36A are also densely arranged in a matrix-like arrangement. Each ventilation hole 35A, 36B is formed into a circle by, for example, laser processing, press processing, etc. (see FIG. 4). In addition, the plurality of ventilation holes 35A are formed in almost the entire area of the side surface 12E in the X direction, and the plurality of ventilation holes 36A are formed in almost the entire area of the side surface 12F in the X direction. In addition, in the Z direction, the communicating parts 35 and 36 are disposed at the same position as each other and are disposed at a position closer to the upper surface 12A of the outer case 12 than to the lower surface 12B of the outer case 12. As a result, the communicating parts 35 and 36 are disposed at a position closer to the heat-generating component 15 that is the main heat source on the circuit board 10. Note that the communicating parts 35 and 36 can also be formed by, for example, forming openings (not shown) in the side surfaces 12E and 12F of the outer case 12, respectively, and fixing a mesh-like member (not shown) such as a wire mesh or a punching plate (not shown) to the outer case 12 by welding or the like so as to close the openings.

In the in-vehicle electronic control device 100 according to the first embodiment described above, the circuit board 10 is housed in the inner case 11, and the inner case 11 is housed in the outer case 12. In other words, the in-vehicle electronic control device 100 has a structure in which the circuit board 10 is doubly surrounded by the inner case 11 and the outer case 12, that is, a double housing structure. Therefore, the circuit board 10 and the inner case 11 can be mechanically protected by the outer case 12. Therefore, for example, when the in-vehicle electronic control device 100 is installed in the passenger compartment, even if the driver or a passenger accidentally hits the in-vehicle electronic control device 100 with their hands or feet, the impact is not directly applied to the inner case 11. Therefore, damage to the inner case 11 due to an external impact can be effectively avoided. In addition, since the circuit board 10 on which the heat-generating components 15 and the connector components 16 are mounted is protected by the inner case 11 within the second space 25 of the outer case 12, there is no risk of impairing the control function of the in-vehicle electronic control device 100 realized by electronic components such as the heat-generating components 15. Therefore, it is possible to provide an in-vehicle electronic control device 100 that can contribute to safer driving assistance and autonomous driving.

In addition to the mechanical protection function described above, the above-mentioned double housing structure also has the function of protecting the inner case 11 from dust and other particles, and the function of facilitating installation of the on-board electronic control device 100 to the vehicle.

The double housing structure is preferably applied to an on-board electronic control device that is mounted inside the vehicle cabin, such as under the driver's seat or passenger's seat, behind the dashboard, or in the trunk, but is not limited thereto and may also be applied to an on-board electronic control device that is mounted in the engine compartment. In other words, an on-board electronic control device having a double housing structure can be applied to an on-board electronic control device that is mounted either inside or outside the vehicle cabin.

Furthermore, in the in-vehicle electronic control device 100 according to the first embodiment described above, a configuration is adopted in which the outer case 12 is provided with communication sections 35, 36. This makes it possible to suppress a decrease in heat dissipation performance when the inner case 11 is housed in the outer case 12. This will be explained in detail below.

FIG. 5 is a perspective view of an on-vehicle electronic control device according to a comparative embodiment, seen from an oblique direction.
5, in the in-vehicle electronic control device 200 according to the comparative embodiment, the circuit board 10 on which the heat generating components 15 and the connector components 16 are mounted is housed in an inner case 11, and this inner case 11 is housed in an outer case 12. Therefore, the effects of mechanically protecting the inner case 11 by the outer case 12, protecting it from dust and the like, and facilitating the installation of the in-vehicle electronic control device 200 can be obtained similarly to the first embodiment. Therefore, the in-vehicle electronic control device 200 according to the comparative embodiment can be one embodiment.

However, in the comparative embodiment of the on-board electronic control device 200, no communication portion is provided in the outer case 12. Therefore, even if air flows as shown by the solid arrows outside the outer case 12, air does not flow from the outside to the inside of the outer case 12, and air does not flow from the inside of the outer case 12 to the outside. Therefore, air convection is unlikely to occur inside the outer case 12.

On the other hand, in the in-vehicle electronic control device 100 according to the first embodiment, the outer case 12 is provided with communication sections 35, 36. As a result, air flows from the outside of the outer case 12 to the inside, and air flows from the inside of the outer case 12 to the outside. Therefore, air convection is likely to occur inside the outer case 12.

Here, in the first embodiment, a communication portion 35 is provided on side 12E of outer case 12, and a communication portion 36 is provided on side 12F opposite side 12E. Furthermore, communication portion 35 is provided in a position close to heat-generating component 15, and communication portion 36 is provided in a position close to connector component 16. Therefore, side 12E on which communication portion 35 is provided is the air inflow side, and side 12F on which communication portion 36 is provided is the air outflow side. The reason for this is as follows.

On the circuit board 10, as shown in FIG. 3, the heat generating component 15 is arranged on one side in the Y direction (left side in FIG. 3), and the connector component 16 is arranged on the other side in the Y direction (right side in FIG. 3). The heat generating component 15 generates a lot of heat, whereas the connector component 16 releases heat to the outside through a harness (not shown). Therefore, the side where the heat generating component 15 is arranged becomes relatively hot, and the side where the connector component 16 is arranged becomes relatively cold. Therefore, as shown by the dashed arrow in FIG. 6, inside the outer case 12, an air flow, i.e., convection, occurs from the side where the heat generating component 15 is arranged to the side where the connector component 16 is arranged. At this time, the air outside the outer case 12 flows into the inside of the outer case 12 through the communication part 35. The air inside the outer case 12 flows out to the outside of the outer case 12 through the communication part 36. Therefore, the side surface 12E on which the communication portion 35 is provided is the air inflow side, and the side surface 12F on which the communication portion 36 is provided is the air outflow side.

In this way, of the two opposing side surfaces 12E, 12F, one side surface 12E is the air inflow side, and the other side surface 12F is the air outflow side, thereby promoting air convection inside the outer case 12. Therefore, even when the in-vehicle electronic control device 100 is placed in the passenger compartment, the heat generated by the heat-generating component 15 as the main heat source can be carried by the air flow from the outer surface of the inner case 11 to the outside of the outer case 12. Therefore, the temperature rise of the electronic components mounted on the circuit board 10, particularly the heat-generating component 15, can be suppressed. Suppressing the temperature rise of the heat-generating component 15 contributes to maintaining the normal function of the CPU and other components built into the heat-generating component 15, and thus to improving the safety of driving assistance and automatic driving.

In addition, the communication part 35 is located on the heat generating component 15 side, and the communication part 36 is located on the connector component 16 side. This makes it possible to further accelerate the air flow generated inside the outer case 12. The principle behind this is explained below.

First, the connector part 16 releases heat to the outside of the outer case 12 through a harness that electrically connects it to the outside. Therefore, the connector part 16 is the part with the lowest temperature among the electronic parts mounted on the circuit board 10, and is also the part with the lowest temperature inside the outer case 12. On the other hand, the heat-generating part 15, which is a high-performance electronic part that consumes high power, is often mounted in a position far from the connector part 16. Here, according to the basic principle of heat conduction, heat in an individual moves from the high temperature side to the low temperature side. Therefore, in the inner case 11, heat moves from the heat-generating part 15 to the connector part 16. Also, the heat flux, which is the amount of heat passing through a unit area per unit time, increases as the temperature difference in the individual increases. Therefore, the greater the temperature difference between the heat-generating part 15 and the connector part 16, the greater the heat flux. On the other hand, air flows from the high pressure side to the low pressure side, that is, from the high temperature side to the low temperature side. Also, the speed at which the air flows increases as the pressure difference and temperature difference increase. Therefore, by providing the communication portion 35 on the heat generating component 15 side and the communication portion 36 on the connector component 16 side, the air flow generated inside the outer case 12 can be further accelerated. This increases the amount of heat transferred, thereby improving the heat dissipation performance of the in-vehicle electronic control device 100. As a result, it is possible to mechanically protect the inner case 11 while ensuring the heat dissipation performance of the in-vehicle electronic control device 100.

Furthermore, inside the outer case 12, air flows in a straight line from the communication part 35 to the communication part 36 due to the temperature difference between the heat-generating component 15 and the connector component 16. This prevents the air from decreasing in speed as it flows inside the outer case 12, allowing air to flow efficiently inside the outer case 12.

In addition, a portion of the air flowing out from communication section 36 flows around the outside of outer case 12, reaches communication section 35, and flows from communication section 35 into the inside of outer case 12. As a result, an air circulation path is formed between the inside and outside of outer case 12 by communication sections 35 and 36. This can promote heat exchange between the air inside and outside outer case 12.

In the first embodiment, the shape of the ventilation holes 35A and 36A is a circle (perfect circle), but the shape of the ventilation holes constituting the communication part may be a polygon. For example, the shape of the ventilation hole 35A may be a square as shown in FIG. 7, a triangle as shown in FIG. 8, or a pentagon as shown in FIG. 9. Although not shown, the shape of the ventilation hole 35A may be an ellipse, a star, a cross, a slit, or the like. Such hole shapes can also be applied to the ventilation hole 36A. The ventilation holes 35A and 36A may be different shapes from each other.

When the shape of the ventilation hole 35A is a shape having at least one corner, such as a polygon, a star, or a cross, the air flow passing through the ventilation hole 35A tends to become turbulent near the ventilation hole 35A. When the air flow becomes turbulent near the ventilation hole 35A, the speed of the air flowing inside the outer case 12 increases. This allows heat to be efficiently released from the outer surface of the inner case 11. This makes it possible to improve the heat dissipation performance of the in-vehicle electronic control device 100.

In addition, in the first embodiment, of the six sides of the outer case 12, a communication portion 35 is provided on side 12E and a communication portion 36 is provided on side 12F, but this is not limited thereto. For example, as shown in FIG. 10, a communication portion 37 may be provided on side 12C of the outer case 12, and a communication portion 38 may be provided on side 12D opposite side 12C.

Also, as shown in FIG. 11, a communication part 35-1 may be provided at one location on the side surface 12E of the outer case 12, and a communication part 35-2 may be provided at another location. The communication part 35-1 is provided at one end of the side surface 12E in the X direction, and the communication part 35-2 is provided at the other end of the side surface 12E in the X direction. The communication part 35-1 is disposed near one heat-generating component 15, and the communication part 35-2 is disposed near the other heat-generating component 15. In this way, even if the communication parts 35-1 and 35-2 are provided only near the heat-generating component 15 on the side surface 12E of the outer case 12, it is possible to obtain the same heat dissipation effect as when the communication part 35 is provided on the entire side surface 12E. Furthermore, when the communication parts 35-1 and 35-2 are provided only near the heat-generating component 15, the effect of protecting the inner case 11 from dust and the like can be enhanced compared to when the communication part 35 is provided on the entire side surface 12E. Although not shown, the side surface 12F of the outer case 12 may also be provided with two separate communication sections (not shown), or a communication section may be provided over the entire side surface 12F.

Second Embodiment
Fig. 12 is a perspective view of the in-vehicle electronic control device according to the second embodiment, seen from an oblique direction. Fig. 13 is a cross-sectional view taken along line CC of the in-vehicle electronic control device shown in Fig. 12, and Fig. 14 is a cross-sectional view taken along line DD of the in-vehicle electronic control device shown in Fig. 12.

As shown in Figures 12 to 14, the in-vehicle electronic control device 100B according to the second embodiment differs from the in-vehicle electronic control device 100 according to the first embodiment described above (see Figures 1 to 3) in that it includes a straightening member 41. The straightening member 41 is a member that straightens the direction of air flowing between the inner case 11 and the outer case 12 (gap portion). The straightening member 41 is composed of multiple plate-shaped portions arranged parallel to the Y direction. The multiple plate-shaped portions that make up the straightening member 41 are lined up at predetermined intervals in the X direction, as shown in Figure 13.

The rectifying member 41 is disposed at a position facing the outer case lid 27 in the Z direction. The material constituting the rectifying member 41 may be resin or metal. When the rectifying member 41 is made of metal, it can function as a heat dissipation fin. The rectifying member 41 as a heat dissipation fin is preferably made of aluminum or an aluminum alloy, which is a metal having high thermal conductivity and excellent corrosion resistance. In addition, the rectifying member 41 is preferably integrally formed with the inner case 11 in order to reduce the number of parts of the in-vehicle electronic control device 100. In this embodiment, the inner case lid 23 and the rectifying member 41 are integrally formed. In this case, the inner case lid 23 and the rectifying member 41 are made of the same metal material, and these integral structures function as a heat sink.

The flow straightening member 41 extends linearly from the side where the heat generating component 15 is arranged to the side where the connector component 16 is arranged. In addition, the side surface 12E where the communication portion 35 is provided and the side surface 12F where the communication portion 36 is provided are arranged to face each other in the Y direction, which is the extension direction of the flow straightening member 41.

On the other hand, a heat transfer member 45 is provided inside the inner case 11. The heat transfer member 45 is a member that transfers heat generated by the heat generating component 15 to the inner case 11. The heat transfer member 45 is made of, for example, a thermally conductive resin, more specifically, a TIM (Thermal Interface Material). The heat transfer member 45 is sandwiched between the heat generating component 15 and the inner case lid 23. The heat transfer member 45 is also in close contact with both the heat generating component 15 and the inner case lid 23. By arranging the heat transfer member 45 in this manner, the heat generated by the heat generating component 15 can be efficiently transferred to the inner case lid 23, and the heat can be released to the outside of the inner case 11 through the inner case lid 23.

In the vehicle-mounted electronic control device 100B configured as described above, the air that has flowed into the outer case 12 through the communication part 35 is oriented by the straightening member 41 when it flows between the inner case 11 and the outer case 12. As a result, inside the outer case 12, the air flows linearly along the Y direction, which is the extension direction of the straightening member 41. Therefore, the air that flows into the outer case 12 through the communication part 35 can reach the communication part 36 while minimizing the decrease in the speed of the air.

In addition, the straightening member 41 extends linearly from the side where the heat-generating component 15 is arranged to the side where the connector component 16 is arranged. Therefore, the direction of the air flow straightened by the straightening member 41 is a constant direction along the Y direction, and is the same as the direction of heat conduction occurring on the outer surface of the inner case 11 due to the temperature difference between the heat-generating component 15 and the connector component 16.

Here, the amount of heat transfer Q can be expressed as the product of the heat flux q and the heat conduction area A. The heat flux q increases due to the temperature difference between the heat generating component 15 and the connector component 16. If there is no air flow, the heat conduction area A does not expand and is constant, but if there is an air flow, it increases according to the expansion of the area. Therefore, if the air that has flowed into the outer case 12 is straightened by the straightening member 41, both the heat flux q and the heat conduction area A increase. As a result, the amount of heat transfer Q increases significantly. Therefore, the heat generated inside the inner case 11 can be efficiently discharged to the outside of the outer case 12. In addition, the heat dissipation performance of the in-vehicle electronic control device 100B can be improved to suppress the temperature rise of the heat generating component 15.

In addition, the straightening member 41 is composed of heat dissipation fins made up of multiple plate-shaped parts. Therefore, heat generated by the heat-generating component 15 as the main heat source can be released from the surface of the straightening member 41 into the second space 25. The air released into the second space 25 can then be carried by the air flow straightened by the straightening member 41 and released to the outside of the outer case 12. This further improves the heat dissipation performance of the in-vehicle electronic control device 100B.

In the second embodiment, the communication portion 35 is provided on the side 12E and the communication portion 36 is provided on the side 12F of the two side surfaces 12E and 12F that face each other in the Y direction, which is the extension direction of the straightening member 41. However, this is not limited to this, and for example, as in the in-vehicle electronic control device 100C shown in FIG. 15, the communication portion 37 may be provided on the side surface 12C and the communication portion 38 may be provided on the opposite side surface 12D. In the in-vehicle electronic control device 100C shown in FIG. 15, the air that has flowed into the inside of the outer case 12 is straightened by the straightening member 41, thereby forming an air flow from the high-temperature heat-generating component 15 side to the low-temperature connector component 16 side. On the other hand, the communication portion 37 provided on the side surface 12C of the outer case 12 and the communication portion 38 provided on the other side surface 12D do not face each other in the extension direction of the straightening member 41, unlike the configuration shown in FIG. 12. Therefore, the speed of the air flowing inside the outer case 12 of the in-vehicle electronic control device 100C shown in FIG. 15 is lower than that of the in-vehicle electronic control device 100B shown in FIG. 12. However, the flow direction of the air rectified by the rectifying member 41 is a constant direction along the Y direction, and is the same as the direction of heat conduction occurring on the outer surface of the inner case 11 due to the temperature difference between the heat-generating component 15 and the connector component 16. Therefore, the heat transfer amount can be increased by the same principle as above, and the heat dissipation performance of the in-vehicle electronic control device 100C can be improved. Such an effect can also be obtained, for example, when the communication part 38 is provided on the side surface 12D and the communication part 36 is provided on the side surface 12F adjacent thereto, as in the in-vehicle electronic control device 100D shown in FIG. 16, or when the communication part 37 is provided on the side surface 12C and the communication part 36 is provided on the side surface 12F adjacent thereto, although not shown.

In the second embodiment, the rectifying member 41 is disposed on the upper surface of the inner case 11, but this is not limited thereto, and the rectifying member 41 may be disposed on the lower surface of the inner case 11. In the second embodiment, the rectifying member 41 is disposed on one surface of the inner case 11, but this is not limited thereto, and the rectifying member 41 may be disposed on multiple surfaces of the inner case 11, for example, by disposing the rectifying member 41 on the upper and lower surfaces of the inner case 11. The rectifying member 41 may be disposed on the outer case 12 instead of the inner case 11. However, in order to make the rectifying member 41 function as a heat dissipation fin, it is preferable to dispose the rectifying member 41 on the inner case 11, which is easily transferred with heat from the heat-generating component 15.

Third Embodiment
FIG. 17 is a perspective view of an on-vehicle electronic control device according to the third embodiment, seen from an oblique direction.
As shown in Fig. 17, the in-vehicle electronic control device 100E according to the third embodiment is different from the in-vehicle electronic control device 100B according to the second embodiment (see Figs. 12 to 14) in that it includes a straightening member 41, but the position of the communication part is different. Specifically, when the in-vehicle electronic control device 100E is mounted on a vehicle, the in-vehicle electronic control device 100E is installed with the upper surface 12A of the outer case 12 facing the top surface and the lower surface 12B of the outer case 12 facing the ground. The communication parts 46 and 47 are each composed of a plurality of air holes. This point is the same in the other embodiments.

The communication portion 46 is formed with an area smaller than that of the communication portion 47. Specifically, the communication portion 46 is formed with an area smaller than half the area of the upper surface 12A, more specifically, an area equal to or smaller than 1/3 of the area of the upper surface 12A. The communication portion 46 is provided in the middle of the upper surface 12A in the X direction, and is formed in a long strip shape in the Y direction, which is the extension direction of the straightening member 41. In contrast, the communication portion 47 is formed with an area larger than half the area of the lower surface 12B, more specifically, over almost the entire area of the lower surface 12B.

In the in-vehicle electronic control device 100E configured as described above, a communication section 46 is provided on the upper surface 12A of the outer case 12, and a communication section 47 is provided on the lower surface 12B of the outer case 12. Therefore, by utilizing the air flow from the ground side to the top side outside the outer case 12, air can be efficiently taken into the inside of the outer case 12, and the taken-in air can be efficiently discharged to the outside of the outer case 12. Therefore, an in-vehicle electronic control device 100E with high heat dissipation performance can be realized.

In addition, by forming communication part 46 with a smaller area than communication part 47, dust suspended in the air is less likely to enter outer case 12 than when communication part 46 is formed with the same area as communication part 47. This improves the function of protecting inner case 11 from dust.

As a modification of the third embodiment, as shown in FIG. 18, a communication section 46-1 may be provided at one location on the top surface 12A of the outer case 12, and a communication section 46-2 may be provided at another location. The communication section 46-1 is provided on the side where the heat-generating component 15 is arranged, and the communication section 46-2 is provided on the side where the connector component 16 is arranged. Furthermore, each of the communication sections 46-1, 46-2 is formed in a long strip shape in the X direction. Even if the communication sections 46-1, 46-2 are provided in two separate locations on the top surface 12A of the outer case 12 in this way, the same effect as above can be obtained.

Fourth Embodiment
FIG. 19 is a cross-sectional view showing an on-vehicle electronic control device according to the fourth embodiment.
As shown in Fig. 19, the in-vehicle electronic control device 100F according to the fourth embodiment is characterized by the relationship between the hole size S1 of the vent hole 35A constituting the communication portion 35 and the hole size S2 of the vent hole 36A constituting the communication portion 36, as compared with the in-vehicle electronic control device 100B according to the second embodiment (see Figs. 12 to 14). In this specification, when the communication portion is constituted by a plurality of vent holes, the hole size of each vent hole is defined by the opening area of the vent hole. For example, if the shape of the vent hole 35A is circular, the hole size S1 of the vent hole 35A is defined by πr2, where r is the radius of the vent hole 35A.

In the in-vehicle electronic control device 100F according to the fourth embodiment, the hole size S1 of the vent hole 35A and the hole size S2 of the vent hole 36A satisfy the relationship S1>S2. In the fourth embodiment, as a more preferred aspect, the hole size S1 of the vent hole 35A and the hole size S2 of the vent hole 36A satisfy the relationship S2/S1≦0.5.

In the in-vehicle electronic control device 100F according to the fourth embodiment, the hole size S2 of the vent hole 36A formed on the air outflow side is smaller than the hole size S1 of the vent hole 35A formed on the air inflow side. Therefore, the speed of the air flowing out of the outer case 12 through each vent hole 36A can be increased, and air convection can be promoted outside the outer case 12. In addition, as the air convection is promoted outside the outer case 12, the speed of the air flowing into the inside of the outer case 12 through each vent hole 35A also increases. Then, the heat transfer rate from the outer surface of the inner case 11 to the air increases due to the increase in the speed of the air flowing into the outer case 12. Therefore, the heat dissipation performance of the in-vehicle electronic control device 100F can be improved. It has been confirmed by a simulation performed by the present inventor that such an effect becomes more remarkable by satisfying the relationship S2/S1≦0.5.

Fifth Embodiment
FIG. 20 is a perspective view of an on-vehicle electronic control device according to the fifth embodiment, seen from an oblique direction.
The in-vehicle electronic control device 100G according to the fifth embodiment is different from the in-vehicle electronic control device 100B according to the second embodiment (see FIGS. 12 to 14) in that, instead of the rectifying member 41 formed of a heat dissipation fin, a heat dissipation pin 50 is provided. The heat dissipation pin 50 dissipates heat generated by the heat-generating component 15 as a main heat source into the gap (second space 25) between the inner case 11 and the outer case 12, and is made of a metal such as aluminum or an alloy. The heat dissipation pin 50 is configured by arranging a plurality of pins in a matrix on the inner case lid 23.

The in-vehicle electronic control device 100G configured as described above can increase the heat transfer area to the air due to the presence of the heat dissipation pins 50, which are an assembly of multiple pins. This improves the heat dissipation performance of the in-vehicle electronic control device 100G.

Sixth Embodiment
FIG. 21 is a perspective view of an on-vehicle electronic control device according to the sixth embodiment, seen from an oblique direction.
As shown in Fig. 21, the in-vehicle electronic control device 100H according to the sixth embodiment is similar to the in-vehicle electronic control device 100B according to the second embodiment (see Figs. 12 to 14) in that it includes a straightening member 41, but the position at which the communication part is provided is different. Specifically, a communication part 48-1 is provided at one location on the upper surface 12A of the outer case 12, and a communication part 48-2 is provided at another location. That is, the communication parts 48-1 and 48-2 are provided at two locations on one surface of the outer case 12. The number of communication parts provided on one surface of the outer case 12 may be two or more. The surface on which the communication part is provided may be the lower surface 12B of the outer case 12.

In this case, it is preferable to provide the communication parts 48-1 and 48-2 at positions separated from each other so that at least one of them is the air inflow side and at least one of them is the air outflow side. In the in-vehicle electronic control device 100H shown in FIG. 21, air flow, i.e., convection, occurs inside the outer case 12 due to the temperature difference between the heat-generating component 15 and the connector component 16 (not shown). Therefore, the communication part 48-1 is provided on the side where the heat-generating component 15 is arranged, and the communication part 48-2 is provided on the side where the connector component 16 is arranged. As a result, even if the communication parts 48-1 and 48-2 are provided on only one surface of the outer case 12, a linear air flow is formed inside the outer case 12, and the heat dissipation performance of the in-vehicle electronic control device 100G can be improved.

The present invention is not limited to the above-described embodiments, but includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H... Electronic control device for vehicle, 10... Circuit board, 15... Heat generating component (electronic component), 16... Connector component (electronic component), 11... Inner case (first housing), 12... Outer case (second housing), 12A... Top surface, 12B... Bottom surface, 12C, 12D, 12E, 12F... Side surface, 35, 35-1, 35-2, 36, 37, 38, 46, 46-1, 46-2, 47, 48-1, 48-2... Communication portion, 35A, 36A... Ventilation hole, 41... Rectification member (heat dissipation fin), 50... Heat dissipation pin

Claims (11)

A circuit board on which electronic components are mounted;
a first housing that houses the circuit board;
a second housing that houses the first housing; and
A bracket that supports the first housing;
Equipped with
the second housing is provided with a communication part that communicates between an outside and an inside of the second housing,
a gap is formed between an outer surface of the first housing and an inner surface of the second housing when the first housing is attached to the second housing by using the bracket;
The gap is formed around the entire periphery of the first housing ,
the communication portion is provided in at least two places in the second housing,
the electronic components include at least a heat generating component disposed on one side of the circuit board and a connector component disposed on the other side of the circuit board;
the communication portion provided at one of the two locations is provided at a position closer to the heat generating component than the connector component, and the communication portion provided at the other location is provided at a position closer to the connector part than the heat generating component,
the communication portion provided at a position closer to the heat generating component than the connector component is configured with a plurality of ventilation holes each having a first hole dimension S1,
the communication portion provided at a position closer to the connector component than the heat generating component is configured with a plurality of ventilation holes each having a second hole dimension S2,
The first hole size S1 and the second hole size S2 are
S1>S2
Satisfying the relationship
In-vehicle electronic control device. The electronic control device for a vehicle according to claim 1 , wherein the two locations are located at positions separated from each other. The electronic control device for vehicle according to claim 2 , wherein the two locations are located at positions separated from each other such that at least one location is an air inflow side and at least the other location is an air outflow side. the second housing is a polyhedron,
The electronic control device for vehicle according to claim 1 , wherein at least one of the two locations is a first surface of the second housing, and at least the other location is a second surface of the second housing that is different from the first surface. The on-vehicle electronic control device according to claim 4 , wherein the first surface and the second surface are disposed in a state where they face each other. The on-vehicle electronic control device according to claim 1 , further comprising a straightening member that straightens a direction of air flowing between the first housing and the second housing. The electronic control device for a vehicle according to claim 6 , wherein the airflow regulating member is configured by a heat dissipation fin. the electronic components include at least a heat generating component disposed on one side of the circuit board and a connector component disposed on the other side of the circuit board;
The electronic control device for vehicle according to claim 6 or 7 , wherein the rectifying member extends linearly from a side where the heat generating component is arranged to a side where the connector component is arranged. The first hole size S1 and the second hole size S2 are
S2/S1≦0.5
The on-vehicle electronic control device according to claim 1 , which satisfies the following relationship: The electronic control device for a vehicle according to claim 1 , wherein the air vent has a shape having at least one corner. The electronic control device for vehicle according to claim 1 , further comprising a heat dissipation pin for dissipating heat generated by the electronic components to a gap between the first housing and the second housing.

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