COOLING UNIT THAT COMPRISES A COMPONENT TO BE COOLED AND A CHANNEL

Abstract

Cooling unit (10) with: a component to be cooled (12) having a plurality of cooling fins (14b); and a channel (20) which is fixed to the component (12) to be cooled and has an outlet (20b), wherein the channel (20) and the component to be cooled (12) define a cooling passage which conveys a gas to an environment around the plurality of cooling fins (14b) and discharges the gas which has passed through the plurality of cooling fins (14b) through the outlet (20b), the cooling passage has a bend (30) between the plurality of cooling fins (14b) and the outlet (20b) of the channel (20), and the channel (20) has an outer corner (32) forming a partition wall on an outer peripheral side of the bend (30), and the channel (20) has a drain hole (34) drilled through the outer corner (32).

Description

BACKGROUND OF THE INVENTION1. Field of the InventionA technique to be disclosed in this application relates to a cooling unit.2. Description of the Prior ArtJP 2008-213 668 A discloses an air intake passage of an automobile engine.DE 197 12 474 C1 and KR 10 2004 0 063 603 A each disclose a cooling unit having a component to be cooled and a duct which is fixed to the component to be cooled and has an outlet, wherein the duct and the component to be cooled define a cooling passage which conveys a gas to an environment around the component to be cooled and discharges the gas which has passed through the component to be cooled through the outlet, and wherein the cooling passage has a bend between the component to be cooled and the outlet of the duct.SUMMARY OF THE INVENTIONIn order to cool a member to be cooled having a plurality of cooling fins, a duct may be mounted on the member to be cooled. In a cooling unit in which a duct is mounted on the member to be cooled, a cooling passage that conveys a gas to an environment around the cooling fins may be formed by a space surrounded by the duct and the member to be cooled. Dew condensation may occur inside this type of cooling unit. The present disclosure provides a cooling unit that can suitably discharge water produced by dew condensation to the outside.An aspect of the present disclosure relates to a cooling unit including a member to be cooled and a duct. The component to be cooled has a plurality of cooling fins. The channel is fixed to the component to be cooled and has an outlet. The channel and the member to be cooled define a cooling passage that conveys a gas to a vicinity around the plurality of cooling fins and discharges the gas that has passed through the plurality of cooling fins through the outlet. The cooling passage has a bend between the plurality of cooling fins and the outlet. The channel has an outer corner forming a partition wall on the outer circumferential side of the bend, and the channel has a drain hole drilled through the outer corner.In this cooling unit, the gas that has passed through the cooling fins passes through the bend and is discharged to the outside of the cooling unit through the outlet. When water is produced by dew condensation inside the cooling unit, this water is forced to flow along an inner wall of the cooling passage by an air pressure. At the bend, the gas flow changes, creating a high air pressure towards the outer side of the curve (i.e. towards the outer corner). Therefore, the water is likely to flow toward the outer corner. Since the drain hole is provided at the outer corner, the water is likely to flow toward the drain hole. When the water reaches the drain hole, the water is discharged by an air pressure to the outside of the cooling unit through the drain hole. Thus, this cooling unit can properly discharge water produced by dew condensation to the outside of the cooling unit.In the cooling unit, the gas may flow toward a lower side in the cooling passage on an upstream side of the bend, and the gas may flow toward an upper side in the cooling passage on a downstream side of the bend.The gas flows towards the lower side means that the gas flow direction comprises at least one vector component directed downwards. Therefore, the gas may flow vertically downward or may flow obliquely downward. That the gas flows toward the upper side means that the gas flow direction includes at least one vector component directed upward. Therefore, the gas may flow vertically upward or may flow obliquely upward.In this configuration, the outer corner is located at a lower part of the bend, so that water is forced to flow to the outer corner (i.e., the drain hole) not only by the air pressure but also by gravity. Therefore, the water can be more properly discharged to the outside of the cooling unit.In the cooling unit, the drain hole may extend downward from the cooling passage.The drain hole may extend vertically downward from the cooling passage or may extend obliquely downward from the cooling passage.In this configuration, the water that has flowed into the drain hole is likely to flow to the outside by gravity. Therefore, the water can be more properly discharged to the outside of the cooling unit.In the cooling unit, the bend may have a valley extending linearly, and the valley may be inclined to fall toward the drain hole.In this configuration, the water is more likely to flow into the drain hole.In the cooling unit, a flow direction of the gas may change by 90° or more at the bend.In this configuration, an air pressure is more likely to be applied to the outer corner, so that the water can be more appropriately discharged to the outside of the cooling unit.In the cooling unit, the area of the drain hole may be not larger than one hundredth of the area of the outlet.In this configuration, gas leakage through the drain hole can be minimized.BRIEF DESCRIPTION OF THE DRAWINGSFeatures, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like reference numerals denote like elements. FIG. 1 is a plan view of a cooling unit; FIG. 2 is a sectional view taken along a line II-II of FIG. 1 ; FIG. 3 is a sectional view taken along a line III-III of FIG. 1 ; and FIG. 4 is a plan view with a channel shown in section.DETAILED DESCRIPTION OF EMBODIMENTSA cooling unit 10 shown in FIG. 1 is installed in a vehicle (an electric vehicle in this embodiment). In the drawings including FIG. 1, arrows UP, FR, and RH indicate an upward direction of the vehicle, a forward direction of the vehicle (advancing direction), and a rightward direction of the vehicle, respectively. The cooling unit 10 includes a DC-DC converter 12, a duct 20, and a blower 40. The channel 20 is mounted on the DC-DC converter 12. The blower 40 sends air into the duct 20, and the air flowing through the duct 20 cools the DC-DC converter 12, and the DC-DC converter 12 is an example of a component to be cooled.As shown in FIGS. 2 and 3, the DC-DC converter 12 has a heat sink 14. The heat sink 14 dissipates heat produced inside the DC-DC converter 12. The heat sink 14 has a base plate 14a and a plurality of cooling fins 14b. The cooling fins 14b are raised from the base plate 14a or stand thereon. The cooling fins 14 bprotrude from the base plate 14 ato a rear side. The cooling fins 14 bextend straight along an up-down direction.As shown in FIG. 1, the channel 20 is a tubular resin member extending from an inlet 20 ato an outlet 20 b. The duct 20 has an upstream part 22, a main part 24 and a downstream part 26. The upstream part 22 connects the inlet 20 aand the main part 24 to each other. The downstream part 26 connects the main part 24 and the outlet 20 bto each other. As shown in FIGS. 2 to 4, a rectangular through hole 28 is provided in a front side partition wall 24 aof the main body 24. The channel 20 is fixed to the DC-DC converter 12 with the cooling fins 14 bbeing inserted into the through hole 28. Thus, the cooling fins 14b are accommodated in the box-shaped main part 24. As shown in FIGS. 2 and 3, a rear partition wall 24 bof the main body 24 faces tips of the cooling fins 14 b. A seal 50 is provided at a junction between the channel 20 and the DC-DC converter 12. The seal 50 seals the connection point between the channel 20 and the DC-DC converter 12. The seal 50 prevents air leakage from the joint.As shown in FIGS. 1 and 4, the blower 40 is connected to the inlet 20 aof the duct 20. The blower 40 is an electric blower and sends air through the inlet 20 aof the duct 20, and a seal 52 is provided at a connection point between the duct 20 and the blower 40. The seal 52 seals the junction between the duct 20 and the fan 40. The seal 52 prevents air leakage from the joint.When the blower 40 is activated, air is supplied from the blower 40 into the upstream portion 22 of the duct 20, as indicated by arrows 100 in FIG. 4. The air flowing through the upstream part 22 flows from an upper side to the inside of the main part 24 as indicated by arrows 100, 102 in FIGS. 3 and 4. In the main body 24, an air flow passage is formed through a space surrounded by the duct 20 and the heat sink 14. In the main body 24, the air flows from an upper side to a lower side. When the air flows through the main body 24, the cooling fins 14 bare cooled by heat exchange between the air and the cooling fins 14 b. Thus, the DC-DC converter 12 is cooled inside the main body 24. As described above, the cooling fins 14 bextend straight along the up-down direction. In the main body 24, the air flows along the extending direction of the cooling fins 14 b(up-down direction). In the main body 24, therefore, the air is less likely to be stagnant, and the cooling fins 14 bare efficiently cooled by the air. As indicated by arrows 102 in FIG. 3, the air that has passed through the main part 24 passes through the downstream part 26 and is discharged to the outside through the outlet 20 b. Thus, a space surrounded by the duct 20 and the DC-DC converter 12 forms a cooling passage that conveys air for cooling the cooling fins 14 b.As indicated by arrows 102 in FIG. 3, the cooling passage (i.e., the air flow direction) bends at a lower side of the cooling fins 14 b. This part of the cooling passage is referred to as a bend 30 hereinafter. The bend 30 is provided between the main part 24 (i.e., the cooling fins 14 b) and the outlet 20 b. On an upstream side of the bend 30 (i.e., in the main body 24), the air flows from the upper side to the lower side. In the bend 30, the air flow direction changes by 90° or more. At a downstream side of the bend 30 (i.e., near the outlet 20b), the air flows obliquely upward.As shown in FIG. 4, the cooling fins 14 bare provided in the main body 24 at intervals in a vehicle width direction. The bend 30 is provided below the main body 24 along an entire surface of the main body 24 in the vehicle width direction. As shown in FIG. 1, the outlet 20 bis elongated in the vehicle width direction. The outlet 20 bis disposed at a higher level than a lowermost part of the bend 30, and as indicated by arrows 100 in FIG. 4, the air flows from the upper side to the lower side in the entire area of the main body 24 in the vehicle width direction (i.e., around the cooling fins 14 b). Thus, in an entire area of the flexure 30 in the vehicle width direction, air flows into the flexure 30 from the upper side. In the bending, in the entire range thereof in the vehicle width direction, the air flow changes its direction to an obliquely upward direction as indicated by arrows 102 in FIG. 3. Therefore, the air is discharged obliquely upward in an entire area of the outlet 20 bin the vehicle width direction.Reference numeral 32 indicated in FIG. 3 denotes an outer corner forming one of partition walls of the duct 20 on an outer circumferential side of the bend 30. The outer corner 32 has a first part 32 aextending downward from the main part 24, a third part 32 cextending obliquely upward toward the outlet 20 b, and a second part 32 bconnecting the first part 32 aand the third part 32 cto each other. In the section shown in FIG. 3 (a vertical section along a front-rear direction of the vehicle), an inner surface of the second part 32 bconstitutes a valley 38 that constitutes a lowermost part (a part located at a lowermost side) of the cooling passage between the main part 24 and the outlet 20 b. As shown in FIG. 4, the valley 38 extends straight along the vehicle width direction. The second part 32 b(i.e., the valley 38) is chamfered to go toward the lower side as it extends toward the center of the main part 24 in the vehicle width direction. At a lowermost portion of the second part 32 b(i.e., at the center thereof in the vehicle width direction), a drain hole 34 is provided which is bored through the second part 32 b. Thus, as shown in FIG. 4, the valley 38 slopes to fall toward the drain hole 34. The drain hole 34 extends downward from the valley 38 (an upper surface of the second part 32 b). The diameter of the drain hole 34 is about 3 mm, and the area of the drain hole 34 is not larger than one hundredth of the area of the outlet 20 b.Inside the cooling unit 10, water (water drops) can be produced by dew condensation. Water droplets may form, for example, on an inner side of the main body 24 (on the cooling fins 14 band an inner surface of the duct 20 around the cooling fins 14 b). When water is produced by dew condensation inside the main body 24, this water flows down an inner surface of the main body 24 due to the air flow and a gravity. Thus, the water flows from the main body 24 into the bend 30, and at the bend 30, the downward air flow (i.e., the air flow toward the outer corner 32) changes its direction to an obliquely upward direction (a direction toward the outlet 20 b). As a result, high air pressure is generated toward the outer corner 32 at the bend 30. Specifically, the air flow changes 90° or more at the bend 30, thereby creating a high air pressure toward the outer corner 32. The water is forced to flow to the outer corner 32 by this air pressure. The water is also forced to flow by gravity to the outer corner 32. When the water arrives at the valley 38 of the outer corner 32, the water is forced by the air pressure and gravity to flow along the valley 38 shown in FIG. 4 toward the center of the valley 38 (i.e., the drain hole 34). When the water reaches the drain hole 34, the water is moved downward through the drain hole 34 by the air pressure and the gravity, and discharged to the outside of the cooling unit 10.As described above, the cooling unit 10 of the embodiment can appropriately discharge water produced inside the cooling unit 10 to the outside of the cooling unit 10 through the drain hole 34. Thus, accumulation of water inside the cooling unit 10 can be prevented. In the cooling unit 10, the area of the drain hole 34 is not larger than one hundredth of the area of the outlet 20 b. Therefore, the amount of air leaking through the discharge hole 34 is extremely small as compared with the amount of air discharged through the outlet 20b. Thus, a situation in which a large amount of high temperature air is discharged to an area under the cooling unit 10 can be prevented.While the embodiment has been described in detail above, this embodiment is merely an example and does not limit the scope of the claims. The technique described in the claims includes various modifications and changes made to the specific examples described above. The technical elements illustrated in this specification or the drawings show their technical utility value independently or in various combinations, and the combinations are not limited to those described in the claims filed. Moreover, the technique illustrated in this specification or drawings can achieve more than one purpose simultaneously, and achieving one of the purposes itself proves its technical utility.A cooling unit (10) has a component (12) to be cooled and a channel (20). The member (12) to be cooled has a plurality of cooling fins (14b). The channel is fixed to the component to be cooled and has an outlet (20b). The channel and the member to be cooled define a cooling passage that conveys a gas to an environment around the fins and discharges the gas that has passed through the fins through the outlet. The cooling passage has a bend (30) between the cooling fins and the outlet. The channel has an outer corner (32) forming a partition wall on an outer circumferential side of the bend, and the channel has a drain hole (34) drilled through the outer corner (32).

Claims

A cooling unit (10) comprising: a member (12) to be cooled having a plurality of cooling fins (14b); and a duct (20) fixed to the member (12) to be cooled and having an outlet (20b), wherein the duct (20) and the member (12) to be cooled define a cooling passage that conveys a gas to a vicinity around the plurality of cooling fins (14b) and discharges the gas that has passed the plurality of cooling fins (14b) through the outlet (20b), the cooling passage has a bend (30) between the plurality of cooling fins (14b) and the outlet (20b) of the duct (20), and the duct (20) has an outer corner (32) that forms a partition wall on an outer circumferential side of the bend (30), and the duct (20) has a discharge hole (34) that is drilled through the outer corner (32).The cooling unit (10) according to claim 1, wherein: the gas flows toward a lower side in the cooling passage on an upstream side of the bend (30); and the gas flows toward an upper side in the cooling passage on a downstream side of the bend (30).The cooling unit (10) of claim 2, wherein the drain hole (34) extends downward from the cooling passage.The cooling unit (10) according to claim 2 or 3, wherein: the bend (30) has a valley (38) extending straight; and the valley (38) is inclined to fall toward the drain hole (34).The cooling unit (10) according to any one of claims 1 to 4, wherein a flow direction of the gas changes by 90° or more at the bend (30).The cooling unit (10) according to any one of claims 1 to 5, wherein an area of the drain hole (34) is not larger than one hundredth of an area of the outlet (20b) of the duct (20).

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