Heat sink, circuit board and traveling body

Abstract

To provide a heat sink, a circuit board and a traveling body which do not deteriorate radiation performance while making an entire structure low.SOLUTION: A heat sink for a circuit board is mounted on a traveling body. The circuit board has a projection component entering into the heat sink. The heat sink has a plurality of fins disposed in parallel to an advancing direction of the traveling body and a wide projection wider than the fin, a partial area of the fin being a fin of reinforced thermal resistance reduction having a shape reinforcing the degree of thermal resistance. Into a part of the wide projection of the wide projection, the projection component enters from its back side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat sink, a circuit board, and a running body that are used in a running body such as a motorcycle or an automobile that is driven by a motor. [Background technology]

[0002] Patent Document 1 describes a method of reducing the height of a circuit board by providing a recess in a case with heat dissipation fins and accommodating a capacitor therein. Since components mounted on a traveling body are required to be space-saving, reducing the height is essential. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-234559 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the circuit board described in Patent Document 1, the priority is given to reducing the height, and the recess for accommodating the capacitor limits the space available for arranging the heat dissipation fins. If the heat dissipation by the fins is insufficient, the heat dissipation performance of the heat sink will be reduced.

[0005] An object of the present invention is to provide a heat sink, a circuit board, and a running body that have a low overall structure and do not reduce heat dissipation performance. [Means for solving the problem]

[0006] In order to achieve this object, the technical means according to the present invention is a heat sink having at least the following configuration.

[0007] A heat sink for a circuit board mounted on a running body, wherein the circuit board has a protruding part that fits into the heat sink, the heat sink has a plurality of fins arranged parallel to the direction of travel of the running body and a wide protruding part that is wider than the fins, and a portion of the fins is a thermal resistance reduction reinforced fin that has a shape that enhances the degree of reduction in thermal resistance, and the protruding part fits into at least a portion of the wide protruding part from the back side.

[0008] In order to achieve the above object, the technical means according to the present invention is a circuit board having at least the following configuration.

[0009] A circuit board mounted on a running body, the circuit board having a heat sink and a protruding part that fits into the heat sink, the heat sink having a plurality of fins arranged parallel to the direction of travel of the running body and a wide protruding part that is wider than the fins, a portion of the fins being a thermal resistance reduction reinforced fin having a shape that enhances the degree of reduction in thermal resistance, and the protruding part fitting into at least a portion of the wide protruding part from the back side.

[0010] In order to achieve the above object, the technical means according to the present invention is a traveling body having at least the following configuration.

[0011] A running body comprising a circuit board, the circuit board having a heat sink and a protruding part that fits into the heat sink, the heat sink having a plurality of fins arranged parallel to the direction of travel of the running body and a wide protruding part that is wider than the fins, a portion of the fins being a thermal resistance reduction reinforced fin having a shape that enhances the degree of reduction in thermal resistance, and the protruding part fitting into at least a portion of the wide protruding part from the back side. [Effects of the Invention]

[0012] By virtue of these characteristics, the present invention has the following advantages. It is possible to provide a heat sink, a circuit board, and a running body that have a low overall structure without deteriorating heat dissipation performance. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view illustrating a motor-integrated circuit board according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the motor-integrated circuit board according to the embodiment of the present invention. [Figure 3] FIG. 2 is a partial exploded view of the motor-integrated circuit board according to the embodiment of the present invention. [Figure 4] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 5] 10 is an explanatory diagram showing the flow of fluid around a heat sink of a conventional motor-integrated circuit board. FIG. [Figure 6] 5A and 5B are explanatory diagrams showing the flow of fluid around a heat sink of the motor-integrated circuit board according to the embodiment of the present invention. [Figure 7] FIG. 10 is a plan view illustrating a circuit board according to another embodiment of the present invention. [Figure 8] FIG. 10 is an explanatory diagram showing a state in which a circuit board according to another embodiment of the present invention is mounted on an electric motorcycle. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an example of an embodiment of a motor-integrated circuit board according to the present invention will be described with reference to the drawings. However, the drawings below have been created for the purpose of explanation, and for the sake of clarity, components not necessary for the explanation may be intentionally omitted. Furthermore, components may be intentionally illustrated larger or smaller for the purpose of explanation, and the drawings are not drawn to an exact scale. In the following description, the same reference numerals in different drawings indicate parts with the same function, and duplicate explanations in each drawing will be omitted as appropriate.

[0015] <Embodiment> (Overall composition) Fig. 1 is a perspective view illustrating a motor-integrated circuit board according to an embodiment of the present invention. Fig. 2 is a plan view of the motor-integrated circuit board according to an embodiment of the present invention. Fig. 3 is a partially exploded view of the motor-integrated circuit board according to an embodiment of the present invention. Fig. 4 is a cross-sectional view taken along line AA in Fig. 2.

[0016] As shown in Figures 1 and 2, in this embodiment, the motor-integrated circuit board is a motor-integrated inverter 100. The motor-integrated inverter 100 is mounted near the rear wheel of an electric motorcycle. The motor-integrated inverter 100 has a heat sink 1 disposed on top of a case 3, and as shown in Figures 3 and 4, an inverter board 2 and a motor are housed inside the case 3. The heat sink 1 is designed to dissipate heat generated by the inverter board 2 and the motor by efficiently combining thermal conduction, convection, and radiation, and its cooling performance is designed so that the heat-generating electronic components such as power transistors and capacitors do not exceed their heat resistance temperatures.

[0017] The heat sink 1 forms the upper layer portion of the motor-integrated inverter 100, and has fins 11, a capacitor housing 12, and screw holes (not shown) arranged on its base 10. Screws 13 are threaded into the screw holes. The capacitor housing 12 and screws 13 have a width greater than that of the fins 11, forming a wide protrusion.

[0018] The base portion 10 is made of a material with high thermal conductivity, such as an aluminum alloy. The fins 11 are made of the same material as the base portion 10, or are formed integrally with the base portion 10. As shown in FIG. 3, a capacitor 21 of the inverter board 2 is inserted into the capacitor housing portion 12 from its back side. The base portion 10 is provided with a screw hole for maintenance, and the screw hole is closed with a screw 13.

[0019] Incidentally, heat dissipation fins are essentially thermal resistance reducing components, with the role of increasing the surface area as much as possible to reduce the thermal resistance of the heat sink. However, the presence of the capacitor housing and screws reduces the area in which the heat dissipation fins can be placed, thereby reducing heat dissipation performance. Therefore, in this embodiment of the present invention, a portion of the fin 11 is made into a specially shaped thermal resistance reduction reinforced fin (111, 112, 113) that enhances the degree of thermal resistance reduction.

[0020] The thermal resistance reduction reinforced fins in this embodiment include a curved fin portion 111, a wall-shaped fin portion 112, and a connecting fin portion 113. The characteristics and significance of each will be explained below, with reference to FIG. 5, which is an explanatory diagram showing the flow of fluid around the heat sink.

[0021] (Bent fin part) As shown in Figures 1 and 2, a base 10 of the heat sink 1 is provided with a plurality of fins 11 arranged parallel to the vehicle's traveling direction. Here, as shown in Figure 2, the center line of the heat sink is defined by a direction parallel to the traveling direction of the electric motorcycle. In Figure 2, the left side is the upstream side of the traveling wind, and the right side is the downstream side of the traveling wind. The bent fin portion 111 is a fin portion formed at an angle so that the tip of the upstream fin 11 faces the center line of the heat sink.

[0022] 5 and 6 are explanatory diagrams showing the flow of fluid around a heat sink, with FIG. 5 showing a conventional embodiment and FIG. 6 showing the present embodiment. Generally, increasing the flow velocity between the heat dissipation fins of a heat sink, i.e., in the space between two fins, promotes heat exchange by convection and reduces the thermal resistance of the heat sink. In a rectangular heat sink, arranging the fins parallel to the vehicle's traveling direction allows the traveling wind to flow evenly between the fins upstream of the heat sink. However, if a cylinder is present in a fluid flowing in a unidirectional direction, the fluid around the cylinder flows along the side of the cylinder. The same is true for a circular heat sink. When the traveling wind collides with the heat sink near its centerline, a stagnation point occurs where the fluid flow velocity becomes zero and the pressure exceeds atmospheric pressure. As a result, part of the flow flows along the arc-shaped periphery to avoid the stagnation point. As shown in FIG. 5, this flow collides with fins formed parallel to the vehicle's traveling direction, causing pressure loss and a decrease in the wind speed between the fins.

[0023] Therefore, in this embodiment, as shown in Figure 2, bent fin sections 111 are placed on both sides of capacitor housing section 12, and are angled so that they face the center line of the heatsink. As shown in Figure 6, bent fin sections 111 guide the traveling wind that flows along the side of the circular heatsink into the spaces between the fins without causing a decrease in wind speed at the inlet between the fins. This allows for lower thermal resistance than conventional fin-shaped heatsinks.

[0024] In this embodiment, the bent portion of the tip of the heat dissipation fin is angled to face the center line of the heat sink to accommodate a circular heat sink, but it may not face the center line. For example, a rectangular heat sink would not have stagnation points, but the cowl shape of the vehicle may cause the airflow to flow from the outside toward the center rather than in a fixed direction. In such cases, it is preferable to angle the bent portion of the tip of the heat dissipation fin so that it faces the outside of the heat sink. Thus, a bent fin is a fin that is angled to correspond to the direction of the airflow when the airflow is not in a fixed direction relative to the heat sink.

[0025] (Wall-shaped fin part) As shown in Figures 1 and 2, the wall-shaped fin portion 112 is a fin portion formed by connecting the rear ends of multiple fins 11 on the downstream side. Generally, when a cylindrical object is placed in a fluid, a stagnation point occurs where the pressure exceeds atmospheric pressure. A boundary layer with a velocity gradient is formed near the wall surface of the object downstream from the stagnation point. The boundary layer becomes thicker as it moves downstream, and at a certain point, the running wind is no longer able to follow the wall surface and separates. Downstream of the point where the running wind separates, a backflow occurs, as shown in Figure 5.

[0026] Let's think about this not just in terms of a cylindrical object, but in terms of a heat sink. Part of the airflow from the moving vehicle flows from upstream to downstream between the heat dissipation fins. Meanwhile, part of the airflow that flows along the periphery of the heat sink and case separates on the downstream side and flows backward. As a result, as shown in Figure 5, the backward flow obstructs the flow of the moving vehicle air from the upstream side. The right diagram of Figure 5 is a cross-sectional view taken along line BB in the left diagram. The speed of the moving vehicle air flowing between the fins, where the flow is obstructed, decreases, causing an increase in the thermal resistance of the heat sink.

[0027] Therefore, in this embodiment, as shown in Figures 1 and 2, the rear ends of multiple fins 11 are connected on the downstream side, so that the wall shape does not obstruct the flow of the wind due to running, as shown in Figure 6. Note that the right diagram in Figure 6 is a cross-sectional view taken along line CC in the left diagram. This prevents an increase in the thermal resistance of the heat sink without reducing the wind speed between the fins.

[0028] Separation on the downstream side of the traveling wind can occur even with objects other than cylindrical objects, and forming the rear ends of multiple heat dissipation fins connected downstream also leads to not obstructing the flow of traveling wind in rectangular inverters. In other words, the wall-shaped fin portion is not a feature unique to circular inverters.

[0029] (Connecting fin part) As shown in Figures 1 and 2, the connecting fin portion 113 is a fin portion formed to connect the upstream sides of short fins arranged side by side, with the upstream and downstream sides of the traveling wind separated by screws 13. Generally, to reduce the thermal resistance of a heat sink, the fluid velocity of the traveling wind or the like near the wall surface of the heat sink is increased, or the surface area of the heat sink is increased. Furthermore, when a heat sink is placed in a fluid such as traveling wind, the fluid velocity is slower downstream than upstream due to the pressure resistance of the heat sink. Therefore, the contribution of an increase in surface area to heat dissipation performance is greater on the upstream side than on the downstream side. In other words, increasing the surface area on the upstream side is more likely to reduce the thermal resistance of the heat sink. However, if a protrusion such as a screw exists on the heat sink in a position that interferes with the heat dissipation fins, making it impossible to form continuous fins from upstream to downstream, as shown in Figure 5, dividing the heat dissipation fins to avoid the protrusions results in smaller upstream fins. This results in a reduced surface area of the heat sink and increased thermal resistance. This also reduces the strength of the heat dissipation fins, which is fatal for inverters mounted on electric motorcycles that may come into contact with flying stones. However, if the divided upstream fins are removed to prevent damage from flying stones, the surface area of the heat sink will decrease and thermal resistance will increase even more.

[0030] Therefore, in this embodiment, the strength of the fins can be increased while maintaining the surface area by connecting the two separated upstream fins as shown in Figures 1 and 2. Also, by aligning one of the two separated upstream fins along the outer periphery of a circular heat sink as shown in Figure 6, the running wind whose speed has not decreased flows along the surface of the circular fin, causing heat exchange on that surface and reducing the thermal resistance of the heat sink.

[0031] <Another embodiment> Fig. 7 is a plan view illustrating a circuit board according to another embodiment of the present invention. Fig. 8 is an explanatory diagram showing how a circuit board according to another embodiment of the present invention is mounted on an electric motorcycle. In the previously described embodiment, the inverter was disposed on the motor near the rear wheel of the electric motorcycle, but in another embodiment, the inverter is disposed on the bottom surface of the main frame below the seat and battery of the electric motorcycle.

[0032] FIG. 7 is a plan view of an inverter according to another embodiment of the present invention, and as can be seen from FIG. 8, the inverter is viewed from below when mounted. In another embodiment, an inverter 100A is installed on the bottom surface of the main frame of an electric motorcycle EB and is connected to the motor via a wire harness. In the mounted form of the inverter 100A, a heat sink 1A is disposed below a case, and an inverter board is housed inside the case. The heat sink 1A efficiently dissipates heat generated by the inverter board by combining thermal conduction, convection, and radiation, and its cooling performance is designed so that the heat-generating electronic components such as power transistors and capacitors do not exceed their heat resistance temperatures.

[0033] The heat sink 1A forms the lower layer portion of the inverter 100A, and has a base portion 10 on which fins 11, a capacitor housing portion 12, and screw holes (not shown) are arranged. Screws 13 are threaded into the screw holes. The capacitor housing portion 12 and the screws 13 have a width greater than that of the fins 11, forming a wide protrusion.

[0034] In another embodiment, similar to the previously described embodiment, a portion of the fin 11 is made into a thermal resistance reduction reinforced fin (112, 113) having a special shape that enhances the degree of reduction in thermal resistance. However, in this embodiment, the thermal resistance reduction reinforced fin only includes a wall-shaped fin portion 112 and a connecting fin portion 113, and does not include a bent fin portion. This is because the inverter is rectangular and the airflow is constant, parallel to the direction of travel, so not only is it unnecessary, but bending the fin tips would actually cause pressure loss and reduce the air speed between the fins. However, in situations where the airflow is not constant due to factors other than the inverter, such as the shape of the motorcycle cowl, a bent fin portion may be provided.

[0035] The heat sink, circuit board, and running body according to the embodiments of the present invention have been described in detail above, but the specific configurations are not limited to these embodiments, and the present invention also includes design changes within the scope of the present invention. For example, while the circuit board has been described as an inverter, the present invention can also be applied to a converter circuit mounted on an electric motorcycle. The subject matter of the present invention should not be understood as being limited to circuit boards. Furthermore, while the embodiments have been described as circuit boards mounted on electric motorcycles, the present invention can also be applied to circuit boards mounted in the engine compartments of a wide range of running bodies, including automobiles in general, not limited to electric vehicles, as long as the airflow from the vehicle can be used for cooling. As explained in this specification, the placement of tall electronic components reduces the area in which the heat dissipation fins can be placed, and to compensate for this, some areas of the fins are given a special shape that enhances the degree of reduction in thermal resistance.However, it should be recognized that there are various types of shapes, and it is not necessary to combine all of them. [Explanation of symbols]

[0036] 1 heat sink 10 Base 11 Finn 111 Bent fin part 112 Wall-shaped fin part 113 Connecting fin part 12 Capacitor housing 13 screws 2 inverter boards 21 Capacitor 100 Motor integrated inverter (motor integrated circuit board) EB electric motorcycle

Claims

1. A heat sink for a circuit board mounted on a traveling body, the circuit board has a protruding part that penetrates into the heat sink; the heat sink has a plurality of fins arranged parallel to the traveling direction of the traveling body and a wide protrusion having a width greater than that of the fins, A partial region of the fin is a thermal resistance reduction reinforcement fin having a shape that enhances the degree of reduction of thermal resistance, The protruding part is inserted into at least a part of the wide protruding part from the rear side thereof. A heat sink characterized by:

2. The thermal resistance reduction reinforced fin is a bent fin portion in which the fin tip on the upstream side is angled with respect to the center line of the heat sink defined by the direction of travel. The heat sink according to claim 1 .

3. the protruding part is a capacitor, The bent fin portions are arranged on both sides of the capacitor, and are angled so as to face the center line of the heat sink.

3. The heat sink according to claim 2.

4. The thermal resistance reduction reinforced fin is a wall-shaped fin portion formed by connecting the rear ends of multiple fins on the downstream side. The heat sink according to claim 1 .

5. The thermal resistance reduction reinforced fin is a connecting fin portion formed to connect the upstream sides of at least two of the short fins arranged side by side and separated by the wide protrusion portion at the upstream and downstream sides in the flow path direction. The heat sink according to claim 1 .

6. The wide protrusion is a screw 6. The heat sink according to claim 5.

7. A heat sink according to any one of claims 1 to 6 is provided. A circuit board comprising:

8. the circuit board is a motor-integrated inverter, The motor housing is connected to the heat sink so that it covers the board.

8. The circuit board according to claim 7.

9. A device comprising the circuit board according to claim 7. A traveling body characterized by:

10. The motor-integrated inverter as the circuit board according to claim 8 is mounted on a driving wheel. A traveling body characterized by:

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