Heat dissipation member and power supply device

Abstract

An object of the present invention is to provide a heat dissipation member and a power supply device that can maintain good cooling performance whether the vehicle is running or stopped. [Solution] The problem was solved by a heat dissipation member for a circuit board mounted on a running body, comprising a case covering the circuit board, a refrigerant flow path formed on the outer casing of the case between an inlet and an outlet, and a plurality of fins extending linearly along the refrigerant flow path, wherein the plurality of fins are separated midway from the inlet to the outlet, and the inter-fin pitch of the plurality of fins arranged on the outlet side is set larger than the inter-fin pitch of the plurality of fins arranged on the inlet side.

Description

[Technical Field]

[0001] The present invention relates to a heat dissipation member for a circuit board mounted on a running body, in particular a heat dissipation member for a circuit board used in a running body such as a motorcycle or automobile driven by a motor, and a power supply device equipped with such a heat dissipation member. [Background technology]

[0002] Conventionally, as a countermeasure against heat generation from heat-generating electronic components used in a traveling vehicle, a heat dissipation member structure has been known in which a recess is provided in a case with heat dissipation fins and a circuit board with a capacitor is housed in the recess. For example, Patent Document 1 describes an inverter device in which a circuit board is housed in a recess adjacent to multiple heat dissipation fins. [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] FIG. 1 is an explanatory diagram showing a conventional heat dissipation member for a circuit board mounted on a running body. FIG. 1 shows a power supply device 100P equipped with a heat dissipation member 1P. In FIG. 1, the lower left of the page is the front of the running body, and the upper right is the rear of the running body. As shown in FIG. 1, the conventional heat dissipation member 1P is provided on the outer casing of a circuit board case 2P. The circuit board case 2P houses circuit boards such as an inverter inside. In the illustration, a motor case 5 is provided below the circuit board case, housing a motor inside. A refrigerant flow path is formed by an inlet Cin that takes in the refrigerant, specifically, the airflow caused by running, and an outlet Cout that discharges the airflow, and multiple heat dissipation fins are provided that extend linearly along the refrigerant flow path. In other words, the multiple heat dissipation fins are the main elements of the heat dissipation member 1P.

[0005] The conventional heat dissipation member 1P is provided with multiple rows of heat dissipation fins, each consisting of a single continuous fin, arranged parallel to the vehicle's traveling direction from front to rear, on the outer casing of the circuit board case 2P. The flow of airflow between the fins improves heat dissipation performance. However, in the midstream to downstream regions, the air pressure between the fins increases, causing the airflow to escape in the direction of lower air pressure, i.e., perpendicular to the vehicle's traveling direction. This results in poor flow of airflow between the fins in the midstream to downstream regions, creating a backflow as if pulled by the airflow escaping between the fins. Because the speed of this backflow is much slower than the airflow, it degrades the heat dissipation performance of the fins in the midstream to downstream regions.

[0006] Furthermore, if multiple fins are formed on the assumption that the wind will flow between the fins while the vehicle is stopped, natural convection will be difficult to achieve, resulting in heat stagnation between the fins and a deterioration in heat dissipation performance.

[0007] The present invention addresses these problems and aims to provide a heat dissipation member and a power supply device that can maintain good cooling performance whether the vehicle is running or stopped. [Means for solving the problem]

[0008] In order to achieve this object, the technical means according to the present invention is a heat dissipation member having at least the following configuration.

[0009] A heat dissipation member for a circuit board mounted on a running body, comprising: a case covering the circuit board; a refrigerant flow path provided on the outer casing of the case and formed between an inlet and an outlet; and a plurality of fins extending linearly along the refrigerant flow path, wherein the plurality of fins are separated midway from the inlet to the outlet, and the fin-to-fin pitch of the plurality of fins arranged on the outlet side is set larger than the fin-to-fin pitch of the plurality of fins arranged on the inlet side.

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

[0011] An in-vehicle power supply device comprising a heat dissipation member for a circuit board, the heat dissipation member having a case covering the circuit board, a refrigerant flow path formed on the outer casing of the case between an inlet and an outlet, and a plurality of fins extending linearly along the refrigerant flow path, the plurality of fins being separated midway from the inlet to the outlet, and the fin-to-fin pitch of the plurality of fins arranged on the outlet side being set larger than the fin-to-fin pitch of the plurality of fins arranged on the inlet 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 dissipation member and a power supply device that can maintain good cooling performance whether the vehicle is running or stopped. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a perspective view of a conventional heat dissipation member and a power supply device. [Figure 2] 1 is a perspective view of a heat dissipation member and a power supply device according to an embodiment of the present invention; [Figure 3] 1 is an exploded perspective view of a power supply device according to an embodiment of the present invention. [Figure 4] 1A and 1B are upper left and upper right perspective views of a heat dissipation member according to an embodiment of the present invention; [Figure 5] 5A, 5B, 5C, 5D are diagrams showing a heat dissipation member according to an embodiment of the present invention, in which FIG. 5A is a front view, FIG. 5B is a left side view, FIG. 5C is a right side view, and FIG. 5D is a bottom view. [Figure 6] 2A to 2C are cross-sectional views of various parts of a heat dissipation member according to an embodiment of the present invention. [Figure 7]10 shows the results of a simulation carried out to verify the difference in flow velocity between the conventional example and the embodiment in the region where the heat dissipation member is disposed. [Figure 8] 10 shows the results of a simulation carried out to verify the difference in temperature distribution between the conventional example and the embodiment in the region where the heat dissipation member is disposed. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, examples of embodiments of a heat dissipation member and a power supply device 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] (Configuration of an embodiment of the present invention) FIG. 2 is a perspective view of a heat dissipation member and a power supply device according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of a power supply device according to an embodiment of the present invention. FIG. 4 is a left upper perspective view and a right upper perspective view of a heat dissipation member according to an embodiment of the present invention. FIG. 5 shows a heat dissipation member according to an embodiment of the present invention, where FIG. 5(a) is a front view, FIG. 5(b) is a left side view, FIG. 5(c) is a right side view, and FIG. 5(d) is a bottom view. FIG. 6 is a cross-sectional view of each part of a heat dissipation member according to an embodiment of the present invention.

[0016] FIG. 2 shows a power supply device 100, such as an inverter, disposed adjacent to the drive shaft of a drive wheel driven by a motor of an electric motorcycle. In the power supply device 100, a heat dissipation member 1 is disposed on a circular circuit board case 2. As shown in FIG. 3, a circuit board 4 on which heat-generating elements such as power transistors and capacitors are mounted is housed within the circuit board case 2. The circuit board case 2 has a recess on the inner surface facing a tall capacitor 41, as shown in FIG. 6, to prevent this. A motor case 5 is provided below the circuit board case 2, and a motor (not shown) is housed inside. The heat dissipation member 1 is a so-called heat sink that efficiently dissipates heat generated by the heat-generating elements by combining thermal conduction, convection, and radiation, and its cooling performance is designed to prevent the heat-generating electronic components, such as the capacitor 41, from exceeding their heat resistance temperature.

[0017] The heat dissipation member 1 has a refrigerant flow path formed by an inlet Cin that takes in airflow caused by running and an outlet Cout that discharges the airflow, and is provided with a plurality of fins 11, 12, and 13 that extend linearly along the refrigerant flow path. However, these fins are not formed as a single continuous piece, but are divided midway from the inlet Cin to the outlet Cout. In the embodiment, the fins are divided at two points, but they may also be divided at one point.

[0018] 2 and 3, upstream fins 11, midstream fins 12, and downstream fins 13 are arranged on the base portion of the heat dissipation member 1. The upstream fins 11, midstream fins 12, and downstream fins 13 are made of a material with high thermal conductivity, such as aluminum or cast metal.

[0019] 2 and 3, six ribs 14 are provided on the outer periphery of the circular circuit board case 2. The ribs 14 are intended to capture the refrigerant that flows along the outer periphery, and are made of a material with high thermal conductivity, such as aluminum or casting.

[0020] 4, the length of the midstream area fins 12 is greater than the lengths of the upstream area fins 11 and the downstream area fins 13. The fin pitch of the midstream area fins 12 is greater than the fin pitch of the upstream area fins 11, and the fin pitch of the downstream area fins 13 is greater than the fin pitch of the midstream area fins 12. In other words, the fin pitch of the multiple fins is set to increase toward the downstream area.

[0021] In a conventional heat dissipation member 1P that has multiple rows of heat dissipation fins made up of a single continuous piece, the air pressure between the fins becomes high in the midstream to downstream area, causing the wind to escape in the direction of lower air pressure, i.e., perpendicular to the vehicle's direction of travel, resulting in a backflow. Because the wind speed of this backflow is much slower than that of the wind, there is a problem in that the heat dissipation performance of the fins in the midstream to downstream area deteriorates.

[0022] In the heat dissipation member 1 of this embodiment, the upstream fins 11 are exposed to the powerful wind during travel and contribute greatly to the heat dissipation effect. Therefore, the upstream fins 11 have a large number of fins and a small fin pitch to maximize their surface area. However, the fin pitches of the midstream fins 12 and downstream fins 13 are gradually wider than the fin pitch of the upstream fins 11 to promote the reverse airflow from the rear to the front of the vehicle. Specifically, the numbers of fins are different: the upstream fins 11 have 14 fins, the midstream fins 12 have 8 fins, and the downstream fins 13 have 6 fins. The wider fin pitch increases the speed of the reverse airflow between the fins. As a result, the heat dissipation performance of the midstream fins 12 and downstream fins 13 can be improved.

[0023] Furthermore, in the conventional heat dissipation member 1P, the rows of heat dissipation fins are configured as one continuous piece, and the pitch between the fins remains small. Therefore, when the vehicle is stopped and there is no wind, the thermal boundary layers of the fins interfere with each other, causing hot air to stagnate between the fins. This causes heat to stagnate between the fins, resulting in a problem of poor heat dissipation performance.

[0024] In the heat dissipation member 1 of this embodiment, the fin pitch between the midstream area fins 12 and the downstream area fins 13 is widened, which promotes natural convection and improves the heat dissipation performance when the traveling object is stopped.

[0025] As can be seen from Figure 5(d), the upper edges of the upstream fins 11, midstream fins 12, and downstream fins 13 are set to the same height position in accordance with the required specifications when they are mounted on a traveling vehicle. However, the bases of the upstream fins 11, midstream fins 12, and downstream fins 13 are positioned at different heights, so the height dimensions of each fin are different. For example, from the DD cross section of Figure 6, it can be seen that the base of the midstream fin 12 is positioned higher because the tall condenser 41 is located on the back side. Furthermore, from the EE cross section of Figure 6, the height position of the base is lower, and as a result, the height dimension of the downstream fin 13 itself is larger.

[0026] Three ribs 14 are provided on the outer periphery of the circuit board case 2 from the upstream area to the downstream area, and six ribs are provided on both sides of the outer periphery of the circuit board case 2. As can be seen from FIG. 5(a), the angles formed by the ribs with the tangent to the circle on the outer periphery of the circuit board case 2 decrease from the upstream area to the downstream area. Each of the ribs 14 is shaped to be oriented along an imaginary line connecting the center CoS of the outlet Cout to the base end of each rib. Furthermore, the length of the ribs 14 protruding from the outer periphery of the circuit board case 2 increases as they move toward the downstream area. These shapes are advantageous for capturing traveling wind traveling along the outer periphery of the circuit board case 2.

[0027] When a conventional heat dissipation member 1P, in which the outer periphery of the circuit board case 2 is simply cylindrical, is placed in a fluid, a flow occurs along the outer periphery of the case, and heat is transferred from the outer periphery of the circuit board case 2 to the traveling wind on the upstream side. Then, when the temperature of the traveling wind increases, the temperature difference between the circuit board case 2 and the traveling wind becomes smaller in the midstream to downstream areas, resulting in a problem of reduced heat dissipation performance.

[0028] The heat dissipation member 1 of this embodiment is able to transfer heat from within the circuit board case 2 to the outer periphery by forming ribs 14 on the outer periphery of the circuit board case 2. Furthermore, by capturing the airflow along the outer periphery of the circuit board case 2 with the ribs 14, the wind speed on the surface of the ribs 14 increases, promoting heat dissipation. Furthermore, the downstream ribs 14 capture the ambient temperature airflow that has not received heat from the circuit board case 2. This ensures a temperature difference between the case and the airflow at each rib even in the midstream to downstream regions, allowing the heat transferred from within the circuit board case 2 to be efficiently dissipated from the ribs 14.

[0029] (Verification of heat dissipation performance) The evaluation of heat dissipation performance using an embodiment of the present invention will now be described. Figure 7 shows the results of a simulation conducted to verify the difference in flow velocity between multiple fins in the area where a conventional heat dissipation member 1P and a heat dissipation member 1 of the embodiment are arranged. Both are cross-sectional views corresponding to the center position along the running direction. The distribution of shading indicates the difference in flow velocity, and the arrows along the curves indicate the direction of air flow. Figure 7(a) shows the flow velocity distribution of the conventional example, and Figure 7(b) shows the flow velocity distribution of the embodiment. Both are cross-sectional views corresponding to the center position along the running direction, and show the state between the fins in the B-B cross-section of Figure 6. Therefore, the upper end of the drawing corresponds to the base of the fin, and the area indicated by the tip of the lead line arrow is lower than the upper edge of the fin. It is difficult to see because the original color image is in grayscale, but in the midstream and downstream areas, which are of particular interest, and particularly in the downstream area, in Figure 7(a), backflow occurs between the fins, reducing the flow velocity and resulting in poor heat dissipation, whereas in Figure 7(b), although backflow occurs between the fins, the flow velocity of the backflow itself is high, resulting in improved heat dissipation compared to the conventional example.

[0030] 8A and 8B are cross-sectional views showing the results of a simulation conducted to verify the difference in temperature distribution around the periphery of the circuit board case in the area where the conventional heat dissipation member 1P and the heat dissipation member 1 of the embodiment are disposed, taken at a position midway between the front and rear. Fig. 8A shows the temperature distribution of the conventional example, and Fig. 8B shows the temperature distribution of the embodiment. In Fig. 8A, heat transferred from the periphery of the circuit board case 2 on the upstream side raises the temperature of the traveling air, and the heated air flows directly along the periphery of the circuit board case 2, so almost no heat dissipation effect can be expected in the midstream and downstream areas. In Fig. 8B, where ribs 14 are provided, cooler air is constantly in contact with each rib, improving heat dissipation.

[0031] The above has described in detail the heat dissipation member and power supply device according to the embodiments of the present invention, but the specific configuration is not limited to these embodiments, and the present invention also includes design changes within the scope of the present invention that do not deviate from the gist of the present invention. For example, an embodiment in which both segmented fins and multiple ribs are provided is advantageous in terms of heat dissipation performance, but the heat dissipation effects of segmented fins and ribs are achieved through a different mechanism, so even if ribs are not provided, the invention can still be considered a heat dissipation measure. In addition, although the case of the electric circuit is circular in the embodiment, the effect of deliberately promoting backflow can be similarly achieved even if the case is rectangular. Furthermore, the circuit board housed inside the case may be another circuit such as a DC-DC converter. In each embodiment, the cooling target has been described as an electric or electronic circuit, but the cooling target may also be an electrical component including a heat-generating mechanical component such as a motor-integrated inverter, etc. Furthermore, the location where the heat dissipation member or power supply device is located is not limited to the drive shaft of the drive wheel driven by the motor of an electric motorcycle, and the present invention also includes the engine room of an automobile. [Explanation of symbols]

[0032] 1 Heat dissipation material 11 Upstream fins 12 Midstream Fin 13 Downstream Fin 14 Ribs 2 Circuit Board Case 4 Circuit Board 41 Capacitor 5 Motor case 100 Power supply

Claims

1. A heat dissipation member for a circuit board mounted on a traveling body, a case that covers a circuit board; a coolant flow path that is provided on an outer periphery of the case and that is formed between an inlet and an outlet; and a plurality of fins that extend linearly along the coolant flow path, The plurality of fins are separated midway from the inlet to the outlet, and the fin pitch of the plurality of fins arranged on the outlet side is set larger than the fin pitch of the plurality of fins arranged on the inlet side. A heat dissipation member characterized by:

2. The plurality of fins are divided into two portions and arranged in an upstream region, a midstream region, and a downstream region, The pitch between the fins is set to increase toward the downstream area. The heat dissipation member according to claim 1 .

3. The upper sides of the fins arranged in the upstream, midstream and downstream regions are positioned at the same height. The heat dissipation member according to claim 2 .

4. The case is circular. The heat dissipation member according to claim 1 .

5. The length of the fins located in the midstream area is greater than the length of the fins located in the upstream and downstream areas. The heat dissipation member according to claim 2 .

6. A heat dissipation member according to any one of claims 1 to 5.

1. A vehicle-mounted power supply device comprising:

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