Oil cooling structure

Abstract

To provide an oil cooling structure that is able to improve cooling efficiency.SOLUTION: An oil cooling structure 1 for cooling lubricating oil of a drive device includes: an oil storage portion 10 disposed in a case of the drive device; and a cooling-liquid flow passage 20 disposed so as to at least partially overlap the oil storage portion 10 in a heat transferable manner and capable of passing cooling liquid therethrough. In the oil cooling structure 1, a plurality of first flow passages 21 are connected to the cooling-liquid flow passage 20 via a second flow passage 25, and a first cooling fin group 40 in which a plurality of fins are arranged in parallel along the first flow passage 21 is provided inside the first flow passage 21. At least one guide fin 50 for guiding the cooling liquid flowing between mutual first cooling fin groups 30, 30 in the pair of first flow passages 21, 21 is provided inside the second flow passage 25 disposed between the pair of first flow passages 21, 21 adjacent to each other in a flow direction of the cooling liquid, in the plurality first flow passages 21.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an oil cooling structure for cooling oil for lubricating a drive unit of a vehicle or the like. [Background technology]

[0002] Conventionally, electric vehicles such as electric automobiles are equipped with a drive motor as a drive device. However, the drive motor has a problem of reduced output efficiency due to heat generated by coils and the like due to overload. To address this problem, a drive device for an electric automobile that cools the drive motor has been disclosed (for example, Patent Document 1).

[0003] The invention described in the above-mentioned Patent Document 1 circulates oil in a case that houses a motor (corresponding to a drive motor), and the circulating oil is cooled by a heat exchange plate. The invention described in the above-mentioned Patent Document 1 also includes a water-cooled chamber defined outside the heat exchange plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-251814 Summary of the Invention [Problem to be solved by the invention]

[0005] Recently, in order to meet the demand for more compact vehicles, the drive motor is housed within the transaxle, and lubrication and cooling of the transaxle along with the drive motor is also required, which calls for further improvements in cooling efficiency.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an oil cooling structure that can uniformly cool oil by making the temperature of the coolant uniform, and can also improve cooling efficiency. [Means for solving the problem]

[0007] (1) The oil cooling structure of the present invention, which is provided to solve the above-mentioned problems, is an oil cooling structure for cooling oil for lubricating a drive unit, and comprises an oil reservoir arranged in a case that houses the drive unit, and a coolant flow path that overlaps at least a portion of the oil reservoir, is arranged to allow heat transfer, and is capable of passing a coolant, wherein the coolant flow path is characterized in that a plurality of first flow paths are connected via second flow paths, and inside the first flow path, a first cooling fin group is provided, in which a plurality of fins are arranged in parallel so as to extend along the first flow path, and inside the second flow path, which is arranged between a pair of the first flow paths adjacent to each other in the flow direction of the coolant, at least one guide fin is provided to guide the coolant flowing between the first cooling fin groups in the pair of first flow paths.

[0008] In the oil cooling structure described above, multiple first flow paths are connected via second flow paths. Among the multiple first flow paths, at least one guide fin is provided inside a second flow path disposed between a pair of adjacent first flow paths in the flow direction of the coolant, guiding the coolant flowing between the first cooling fin groups in the pair of first flow paths. In other words, the guide fin is disposed between a pair of adjacent first cooling fin groups in the flow direction of the coolant and guides (rectifies) the coolant flowing between the pair of first cooling fin groups. Therefore, the oil cooling structure described above allows the coolant to flow smoothly within the coolant flow path. Therefore, the oil cooling structure described above can equalize the temperature at the inlet side (upstream side) of the coolant and the temperature at the outlet side (downstream side) of the coolant. This allows the oil cooling structure described above to improve cooling efficiency. Because the oil cooling structure described above can improve cooling efficiency, it is expected that the oil cooling structure can be made more compact.

[0009] Here, the coolant may be, for example, cooling water or an antifreeze such as ethylene glycol. Furthermore, the oil cooling structure described above allows heat exchange between the pair of first cooling fin devices by connecting or arranging the pair of first cooling fin groups in close proximity (arranged with a small gap) using guide fins so that heat can be transferred between them. Therefore, the oil cooling structure described above is expected to further improve cooling efficiency and enable further miniaturization of the oil cooling structure.

[0010] (2) The oil cooling structure of the present invention described above may be characterized in that the plurality of first flow paths are connected to each other in a serpentine manner via the second flow paths, the second flow paths are formed in a curved shape, and the guide fins are curved along the curve of the second flow paths and are positioned midway inside the second flow paths.

[0011] The above-described oil cooling structure, by being configured as described above, can smoothly rectify the oil flow along the curved (radial) guide fins. This allows the above-described oil cooling structure to uniformly distribute the temperature of the coolant in the coolant flow path, thereby further improving cooling efficiency. Furthermore, by connecting or arranging a pair of first cooling fin groups adjacent to each other in the coolant flow direction by the guide fin, the pair of first cooling fin groups can transfer heat to each other via the guide fin, thereby uniformizing the temperature on the inlet side (upstream side) of the coolant and the temperature on the outlet side (downstream side) of the coolant. This allows the above-described oil cooling structure to be expected to further improve cooling efficiency.

[0012] (3) In the oil cooling structure of the present invention, the oil reservoir may have a second cooling fin group consisting of a plurality of fins arranged in parallel, and the first cooling fin group and the second cooling fin group may be in direct or indirect contact with each other at least in part so as to be able to transfer heat to each other.

[0013] The above-described oil cooling structure, by being configured as described above, can transfer heat (heat exchange) uniformly and quickly between the first cooling fin group and the second cooling fin group, thereby increasing the oil cooling efficiency.

[0014] (4) In the oil cooling structure of the present invention described above, the oil reservoir may have a second cooling fin group consisting of a plurality of fins arranged in parallel, and the first cooling fin group may be arranged across the second cooling fin group in a plan view so that at least a portion of the first cooling fin group is in direct or indirect contact with the second cooling fin group so as to be capable of transferring heat to each other.

[0015] The above-described oil cooling structure, by being configured as described above, can transfer heat (heat exchange) uniformly and quickly between the first cooling fin group and the second cooling fin group, thereby increasing the oil cooling efficiency.

[0016] (5) In the oil cooling structure of the present invention described above, the oil reservoir may have a second cooling fin group consisting of a plurality of fins arranged in parallel, and the first cooling fin group and the second cooling fin group may be arranged so that at least a portion of each fin overlaps with each other and heat can be transferred.

[0017] The above-described oil cooling structure, by being configured as described above, can transfer heat (heat exchange) uniformly and quickly between the first cooling fin group and the second cooling fin group, thereby increasing the oil cooling efficiency.

[0018] (6) In the oil cooling structure of the present invention described above, the oil reservoir has a second cooling fin group consisting of a plurality of fins arranged in parallel, a heat-transferable connecting wall is provided between the first cooling fin group and the second cooling fin group, and the first cooling fin group and the second cooling fin group are arranged so that at least a portion of them overlap each other via the connecting wall and are heat-transferable.

[0019] The oil cooling structure described above can transfer heat (heat exchange) through a connecting wall provided between the first cooling fin group and the second cooling fin group. Furthermore, since the oil cooling structure described above has the connecting wall, the connecting wall can be part of the fins. This allows the oil cooling structure described above to improve the oil cooling efficiency. Here, the connecting wall can be, for example, the bottom wall of the oil reservoir. This allows the oil cooling structure described above to reduce the distance between the first cooling fin group and the second cooling fin group, which is expected to improve the oil cooling efficiency and reduce the size of the oil cooling structure.

[0020] (7) In the oil cooling structure of the present invention described above, the oil reservoir may have a second cooling fin group consisting of a plurality of fins arranged in parallel, and the second cooling fin group may be arranged in a direction intersecting the direction in which the first cooling fin group is arranged so as to enable heat transfer with the first cooling fin group.

[0021] The above-described oil cooling structure has such a configuration that the fins in the first cooling fin group and the second cooling fin group are in direct or indirect contact with each other. Therefore, the above-described oil cooling structure can uniformly and quickly perform heat exchange in the first cooling fin group and the second cooling fin group. As a result, the above-described oil cooling structure can uniformly and quickly cool the oil.

[0022] (8) In the oil cooling structure of the present invention described above, the second cooling fin group may be arranged in a direction perpendicular to the direction in which the first cooling fin group is arranged so as to enable heat transfer with the first cooling fin group.

[0023] The above-described oil cooling structure has such a configuration that the fins in the first cooling fin group and the second cooling fin group can be in direct or indirect contact with each other. Furthermore, in the above-described oil cooling structure, the second cooling fin group is arranged in a direction perpendicular to the direction in which the first cooling fin group is arranged, allowing the first cooling fin group and the second cooling fin group to overlap over a wide area. Therefore, the above-described oil cooling structure can perform heat exchange in the first cooling fin group and the second cooling fin group more uniformly and quickly. This allows the above-described oil cooling structure to cool the oil more uniformly and quickly.

[0024] (9) In the oil cooling structure of the present invention described above, the oil reservoir has a second cooling fin group consisting of a plurality of fins arranged in parallel, the oil reservoir and the coolant flow path are arranged adjacent to each other, the first cooling fin group is provided on the coolant flow path side inside the oil reservoir, and the second cooling fin group is provided on the oil reservoir side inside the coolant flow path.

[0025] The above-described oil cooling structure has such a configuration that the first cooling fin group and the second cooling fin group are arranged close to each other, thereby enabling efficient heat exchange between the oil and the coolant. Therefore, the above-described oil cooling structure can improve oil cooling efficiency. Furthermore, even when the oil reservoir and the coolant flow path are mounted in the engine compartment of a vehicle, and the exterior of the oil reservoir and the coolant flow path is exposed to heat generated by the engine, drive motor, or the like, the above-described oil cooling structure can reduce the effects of the heat generated.

[0026] (10) In the oil cooling structure of the present invention described above, the coolant flow path may be arranged so that the first flow path is denser upstream of the oil inflow side of the oil reservoir than the oil discharge side.

[0027] The oil cooling structure described above can efficiently cool oil that has been heated during lubrication. That is, the oil cooling structure described above allows low-temperature coolant to act closely on the oil that has been heated during lubrication, thereby efficiently exchanging heat.

[0028] (11) The oil cooling structure of the present invention may be characterized in that the coolant flow path is disposed below the oil reservoir and functions as an oil cooler.

[0029] The above-described oil cooling structure can eliminate the need for an oil cooler or, if an oil cooler is provided, reduce the capacity of the oil cooler, thereby enabling the drive unit (including the transaxle) to be made smaller.

[0030] (12) The oil cooling structure of the present invention described above may be characterized in that the drive device is either one or both of a drive motor and a generator motor in a vehicle.

[0031] The oil cooling structure described above, by being configured as described above, can efficiently cool the drive motor and the generator motor, thereby suppressing a decrease in the output of the drive motor and a decrease in the power generation efficiency of the generator motor. [Effects of the Invention]

[0032] According to the present invention, it is possible to provide an oil cooling structure that can uniformly cool oil by making the liquid temperature of the coolant uniform, and can also improve cooling efficiency. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a partially cutaway perspective view of an oil cooling structure according to an embodiment of the present invention; [Figure 2] 2 is a plan view of an oil reservoir that constitutes a part of the oil cooling structure according to the embodiment of the present invention. FIG. [Figure 3] FIG. 3 is a bottom view of FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along the arrow AA in FIG. 2. [Figure 5] FIG. 3 is a cross-sectional view taken along the arrow BB in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0034] An oil cooling structure 1 according to one embodiment of the present invention will now be described in detail with reference to the accompanying drawings. These drawings are schematic diagrams and are not necessarily drawn to exact scale. In addition, similar components in the drawings are designated by similar reference numerals. It should be noted that hatching representing cross sections has been omitted in FIGS. 4 and 5. In this embodiment, the oil cooling structure 1 will be described as being used in a transaxle of an electric vehicle.

[0035] 1 and 2, the oil cooling structure 1 includes an oil reservoir 10 and a coolant flow path 20. In addition to the above, the oil cooling structure 1 also includes a first cooling fin group 30 provided inside the coolant flow path 20, and a second cooling fin group 40 provided inside the oil reservoir 10. In the oil cooling structure 1 of this embodiment, the coolant flow path 20 is arranged below the oil reservoir 10.

[0036] The oil reservoir 10 is attached to the lower side of the transaxle (corresponding to a drive unit, not shown). The oil reservoir 10 is intended to store oil (e.g., ATF: Automatic Transmission Fluid) for lubricating the transaxle. The oil is supplied to the transaxle by an oil pump (not shown) and then collected in the oil reservoir 10.

[0037] The transaxle case described above houses a drive motor, a transmission, a differential gear, etc. In addition to the above, the transaxle may also house a generator motor, an inverter, etc.

[0038] As shown in Fig. 2, the oil reservoir 10 is formed in a rectangular shape in a plan view. The oil reservoir 10 is roughly divided into an oil inflow side (upstream side, inlet side) on the right side of the figure and an oil outflow side (downstream side, outlet side) on the left side of the figure. The bottom wall of the oil reservoir 10 is formed as a connection wall 15 (also referred to as bottom wall 15) described below. The case of the oil reservoir 10 is formed by casting or the like using a metal material such as aluminum or iron.

[0039] An oil outlet 11 is provided on the oil outflow side of the bottom wall 15 of the oil reservoir 10. In addition, a second cooling fin group 40 formed of a plurality of fins 41 is provided inside the oil reservoir 10.

[0040] In this embodiment, the second cooling fin group 40 is divided into two, an oil inflow side and an oil outflow side. For convenience of explanation, the second cooling fin group 40 on the oil inflow side may be referred to as the inflow side second cooling fin group 40R, and the second cooling fin group 40 on the oil outflow side may be referred to as the outflow side second cooling fin group 40L.

[0041] The inlet-side second cooling fin group 40R is formed in a substantially square shape to fit the inner wall of the oil reservoir 10. The inlet-side second cooling fin group 40R is formed by erecting a plurality of fins 41 on the connecting wall 15 so that they are parallel to each other in the left-right direction in the figure. That is, the inlet-side second cooling fin group 40R has a plurality of fins 41 erected in parallel along the direction from the upstream side to the downstream side of the oil flow. This allows the oil to be smoothly discharged from the inlet side to the outlet side. The fins 41 are formed of rectangular plate-like members, as shown in FIGS. 1 and 4. Furthermore, the fins 41 are formed from a metal with good heat exchange properties, such as aluminum, to ensure smooth heat exchange.

[0042] The second outlet-side cooling fin group 40L is disposed at a distance from the second inlet-side cooling fin group 40R. The second outlet-side cooling fin group 40L is formed in a rectangular shape to fit the inner wall, and like the second inlet-side cooling fin group 40R, is erected on the connecting wall 15 so that the multiple fins 41 are parallel to each other in the left-right direction in the figure. As will be described in detail later, the second cooling fin group 40 is disposed in a direction intersecting (perpendicular in this embodiment) the direction in which the first cooling fin group 30 is disposed in the coolant flow path 20, which will be described later. The second cooling fin group 40 may be formed directly on the connecting wall 15, or may be formed separately from the connecting wall 15 and fixed thereto.

[0043] The oil discharge port 11 is provided downstream (upper side in the figure) of the outlet-side second cooling fin group 40L. The oil discharge port 11 discharges oil and supplies the discharged oil to an oil pump (not shown). This allows the oil to be supplied into the transaxle to lubricate and cool the drive motor and other components.

[0044] 3, the coolant flow path 20 is formed by connecting a pair of first flow paths 21, 21 adjacent to each other in the flow direction of the coolant (the left-right direction in the figure) in a serpentine shape (also referred to as a zigzag shape) via a second flow path 25, thereby forming a single flow path. The coolant flow path 20 is capable of passing through the coolant. Here, the coolant may be, for example, cooling water or an antifreeze liquid such as ethylene glycol.

[0045] The coolant flow path 20 is arranged so as to at least partially overlap the oil reservoir 10 and enable heat transfer. In this embodiment, the coolant flow path 20 is arranged so as to overlap with the arrangement area of ​​the inlet-side second cooling fin group 40R and the arrangement area of ​​the outlet-side second cooling fin group 40L. Specifically, the coolant flow path 20 is divided into the arrangement area of ​​the inlet-side second cooling fin group 40R and the arrangement area of ​​the outlet-side second cooling fin group 40L, and the divided coolant flow paths 20, 20 are connected by a pipe 22.

[0046] The coolant flow path 20 is formed on the rear surface side of the connecting wall 15 that forms the bottom wall 15 of the oil reservoir 10. That is, the upper wall of the coolant flow path 20 is shared with the bottom wall 15 of the oil reservoir 10 as the connecting wall 15. Therefore, the connecting wall 15 is capable of transferring heat and functions as a cooling fin. The connecting wall 15 separates the oil and the coolant to prevent them from mixing.

[0047] As shown in FIG. 3, the coolant flow path 20 has a plurality of first flow paths 21 and a second flow path 25 that is provided between the plurality of first flow paths 21 and connects the plurality of first flow paths 21 as a single serpentine (also called zigzag) flow path.

[0048] The first flow paths 21 are formed linearly and are arranged in parallel with a gap between them so as to be adjacent in the direction of the coolant flow. In this embodiment, the first flow paths 21 are arranged so as to be densely packed upstream of the oil inflow side of the oil reservoir 10 relative to the oil discharge side. This allows the oil cooling structure 1 described above to efficiently cool the oil that has been used for lubrication and has generated heat. That is, the oil cooling structure 1 described above can allow low-temperature coolant to act closely on the oil that has been used for lubrication and has become hot, thereby efficiently conducting heat transfer (heat exchange). Note that the first flow paths 21 are not limited to those formed linearly, and can be formed in various shapes (e.g., S-shape) as long as they do not obstruct the flow of the coolant.

[0049] A first cooling fin group 30 formed of a plurality of fins 31 is provided inside the first flow path 21. In this embodiment, the plurality of fins 31 forming the first cooling fin group 30 have the same configuration as the fins 41 used in the above-described second cooling fin group 40, and therefore detailed description thereof will be omitted.

[0050] The first cooling fin group 30 is arranged in parallel to the first flow path 21. Therefore, in this embodiment, the first cooling fin group 30 is arranged in a direction intersecting (perpendicular to) the direction in which the second cooling fin group 40 is arranged (see FIG. 2). The fins 31 of the first cooling fin group 30 are erected (hanging) from the lower surface of the connecting wall 15 (see FIGS. 1, 4, and 5). That is, the connecting wall 15 is provided between the first cooling fin group 30 and the second cooling fin group 40. Therefore, the first cooling fin group 30 and the second cooling fin group 40 are positioned so that at least a portion of them overlap with each other via the connecting wall 15 and are heat-transferable. In other words, the first cooling fin group 30 is arranged to straddle the second cooling fin group 40 in a plan view so that at least a portion of them directly or indirectly contact each other and are heat-transferable with each other (see FIG. 2).

[0051] Therefore, the above-described oil cooling structure 1 can perform uniform heat transfer (heat exchange) between the first cooling fin group 30 and the second cooling fin group 40. Specifically, the plurality of fins 31 constituting the first cooling fin group 30 and the plurality of fins 41 constituting the second cooling fin group 40 are in direct or indirect contact with each other, thereby performing uniform and rapid heat exchange between the first cooling fin group 30 and the second cooling fin group 40. This allows the above-described oil cooling structure 1 to improve the oil cooling efficiency.

[0052] Here, when the oil reservoir 10 and the coolant flow path 20 employing the oil cooling structure 1 are mounted in an engine compartment as in this embodiment, they may be affected by heat generated by, for example, an engine or a motor. Therefore, in order to reduce the effect of the heat generated, in this embodiment, the oil reservoir 10 and the coolant flow path 20 are arranged adjacent to each other, and the first cooling fin group 30 is provided on the coolant flow path 20 side inside the oil reservoir 10, and the second cooling fin group 40 is provided on the coolant flow path 20 side inside the oil reservoir 10.

[0053] By configuring the oil cooling structure 1 as described above, even when the outside of the oil reservoir 10 and the coolant flow path 20 are exposed to heat generated by the engine, drive motor, etc., the influence of the heat can be reduced. Furthermore, in the oil cooling structure 1 described above, the first cooling fin group 30 and the second cooling fin group 40 are arranged close to each other, so heat exchange between the oil and the coolant can be performed efficiently. As a result, the oil cooling structure 1 described above can improve the oil cooling efficiency.

[0054] The second flow path 25 connects the downstream side (outlet side) of one of the pair of first flow paths 21, 21 to the upstream side (inlet side) of the other first flow path 21. In this embodiment, the second flow path 25 is formed in an arc shape (U-shape, curved shape).

[0055] Among the multiple first flow paths 21, a second flow path 25 is arranged between a pair of adjacent first flow paths 21, 21 in the flow direction of the coolant, and a guide fin 50 is provided between the first cooling fin groups 30, 30 in the pair of first flow paths 21, 21.

[0056] The guide fin 50 guides (straightens) the coolant flowing between the pair of first cooling fin groups 30, 30. The guide fin 50 is formed, for example, by bending a plate-shaped member made of a metal with good heat conductivity, such as aluminum, into a curved shape along the second flow path 25. The guide fin 50 is disposed midway (preferably at the center) inside the second flow path 25.

[0057] Furthermore, the guide fin 50 connects a pair of first cooling fin groups 30, 30 adjacent to each other in the coolant flow direction so as to enable heat transfer between them. This enables heat exchange between the pair of first cooling fin groups 30, 30 adjacent to each other in the coolant flow direction. Therefore, the above-described oil cooling structure 1 is expected to further improve cooling efficiency and further reduce the size of the oil cooling structure 1. Note that the guide fin 50 need not necessarily connect the pair of first cooling fin groups 30, 30 to each other, but may also be arranged closely with a small gap between them to enable heat transfer.

[0058] The above is the configuration of the oil cooling structure 1 according to one embodiment of the present invention. Next, the effects of the oil cooling structure 1 of the present invention will be described.

[0059] In the oil cooling structure 1 described above, multiple first flow paths 21 are connected via second flow paths 25. Among the multiple first flow paths 21, at least one guide fin 50 is provided inside the second flow path 25, which is disposed between a pair of adjacent first flow paths 21 in the coolant flow direction. The guide fin 50 guides the coolant flowing between the first cooling fin groups 30 in the pair of first flow paths 21. In other words, the guide fin 50 is disposed between the pair of adjacent first cooling fin groups 30 in the coolant flow direction and guides (rectifies) the coolant flowing between the pair of first cooling fin groups 30. Therefore, the oil cooling structure 1 described above allows the coolant to flow smoothly within the coolant flow path 20. Therefore, the oil cooling structure 1 described above can equalize the temperature at the inlet side (upstream side) of the coolant and the temperature at the outlet side (downstream side) of the coolant. This allows the oil cooling structure 1 described above to improve cooling efficiency. In this way, the above-described oil cooling structure 1 can improve the cooling efficiency, and is therefore expected to reduce the size of the oil cooling structure 1. In this embodiment, the first cooling fin group 30 is not provided on the downstream side of the second flow path 25 (the rightmost side in FIG. 3 ), but the first cooling fin group 30 may be provided inside the second flow path 25.

[0060] Furthermore, in the oil cooling structure 1 described above, the second flow passage 25 is formed in a curved shape, and the guide fin 50 is curved along the curve of the second flow passage 25 and is positioned midway within the second flow passage 25. Therefore, the oil cooling structure 1 described above can smoothly rectify the oil along the curved (radial) guide fin 50. As a result, the oil cooling structure 1 described above can uniform the temperature of the coolant in the coolant flow passage 20, thereby further improving the cooling efficiency. Furthermore, a pair of first cooling fin groups 30, 30 adjacent to each other in the flow direction of the coolant are connected or positioned adjacent to each other by the guide fin 50, thereby enabling heat transfer between the pair of first cooling fin groups 30, 30 via the guide fin 50, thereby uniforming the temperature on the inlet side (upstream side) of the coolant and the temperature on the outlet side (downstream side) of the coolant. As a result, the oil cooling structure 1 described above is expected to further improve the cooling efficiency. The guide fin 50 may be positioned so as to straddle the first cooling fin group 30.

[0061] Furthermore, in the above-described oil cooling structure 1, the oil reservoir 10 has a second cooling fin group 40 consisting of a plurality of fins 41 arranged in parallel, and a heat-transferable connecting wall 15 is provided between the first cooling fin group 30 and the second cooling fin group 40, and the first cooling fin group 30 and the second cooling fin group 40 are arranged so that at least a portion of them overlap each other via the connecting wall 15, allowing heat transfer.

[0062] Therefore, the above-described oil cooling structure 1 can exchange heat via the connecting wall 15 provided between the first cooling fin group 30 and the second cooling fin group 40. Furthermore, because the above-described oil cooling structure 1 has the connecting wall 15, the connecting wall 15 can be made part of the fins. This allows the above-described oil cooling structure 1 to improve the oil cooling efficiency. Furthermore, the bottom wall 15 of the oil reservoir 10 is used as the connecting wall 15. This allows the above-described oil cooling structure 1 to reduce the distance between the first cooling fin group 30 and the second cooling fin group 40, which is expected to improve the oil cooling efficiency and make the oil cooling structure 1 more compact.

[0063] Furthermore, in the above-described oil cooling structure 1, the second cooling fin group 40 is arranged in a direction intersecting the direction in which the first cooling fin group 30 is arranged, allowing the fins 31, 41 of the first cooling fin group 30 and the second cooling fin group 40 to come into direct or indirect contact with each other. Furthermore, in the above-described oil cooling structure 1, the second cooling fin group 40 is arranged in a direction perpendicular to the direction in which the first cooling fin group 30 is arranged, allowing the first cooling fin group 30 and the second cooling fin group 40 to overlap over a wide area. Therefore, the above-described oil cooling structure 1 can perform heat exchange between the first cooling fin group 30 and the second cooling fin group 40 more uniformly and quickly. As a result, the above-described oil cooling structure 1 can cool the oil more uniformly and quickly. Note that the second cooling fin group 40 does not necessarily have to overlap with the first cooling fin group 30, but may also overlap with the guide fin 50.

[0064] Furthermore, the above-described oil cooling structure 1 can function as an oil cooler because the coolant flow path 20 is disposed below the oil reservoir 10. Therefore, the above-described oil cooling structure 1 can eliminate the need for an oil cooler, or, if an oil cooler is provided, reduce the capacity of the oil cooler. As a result, the above-described oil cooling structure 1 can reduce the size of the drive unit (including the transaxle).

[0065] Furthermore, when the drive device is either or both of a drive motor and a generator motor in a vehicle, the above-mentioned oil cooling structure 1 can efficiently cool the drive motor and the generator motor, thereby suppressing a decrease in the output of the drive motor and a decrease in the power generation efficiency of the generator motor.

[0066] The above is the configuration and effects of the oil cooling structure 1 according to one embodiment of the present invention, but the oil cooling structure 1 of the present invention is not limited to the above-described embodiment and can be modified in various ways.

[0067] In this embodiment, the drive unit is a transaxle (drive motor, transmission, and differential gear) in an electric vehicle, but the oil cooling structure 1 described above is not limited to this and can be used in various drive units. For example, a transaxle used as a drive unit may be equipped with, for example, a generator motor, an inverter, an engine, etc. Furthermore, various drive sources can be used for the drive unit, such as not only transaxles but also those equipped with a drive motor, a generator motor, an engine, etc., either individually or in combination.

[0068] Furthermore, the oil reservoir 10 is not limited to the one described in the above embodiment; various shapes and sizes can be used. In the present embodiment, ATF lubricating the transaxle is used as the oil to be cooled. However, the oil cooling structure 1 described above can be used with various types of oil. For example, the oil may not be lubricating oil but simply cooling oil. In the present embodiment, the coolant flow path 20 is formed using the bottom wall 15 (connecting wall 15) of the oil reservoir 10. However, the coolant flow path 20 is not limited to this and can be formed in various forms, shapes, and sizes. For example, the coolant flow path 20 may be formed in a tubular shape independent of the oil reservoir 10. The connecting wall 15 may be provided as needed, and a configuration without the connecting wall 15 is also possible. The connecting wall 15 need not be shared with the bottom wall 15 of the oil reservoir 10; it may be provided in various locations, such as separately from the bottom wall 15 or on a side wall other than the bottom wall 15.

[0069] Furthermore, the first flow path 21 does not have to be formed linearly, but can be formed in various shapes as long as the flow of the coolant is not obstructed. Furthermore, in this embodiment, the first flow path 21 and the second flow path 25 do not have to be formed independently of each other, but can be formed integrally. Furthermore, the arrangement of the first cooling fin group 30 inside the first flow path 21 does not have to be formed along the first flow path 21, but can be formed in various directions as long as the flow of the coolant is not obstructed.

[0070] Furthermore, the second cooling fin group 40 is not limited to the shape and size of the embodiment described above, and can be formed into various shapes and sizes according to the shape and size of the oil reservoir 10. Furthermore, in this embodiment, the second cooling fin group 40 is divided into an inflow-side second cooling fin group 40R and an outflow-side second cooling fin group 40L, but various types of second cooling fin groups 40 can be used, such as a single group or a group divided into three or more groups.

[0071] Furthermore, in this embodiment, the first cooling fin group 30 and the second cooling fin group 40 are formed of the same fins 31, 41. However, the fins 31, 41 forming the first cooling fin group 30 and the second cooling fin group 40 may be formed of different materials, for example, in consideration of heat transfer properties. The guide fin 50 can also be formed of various materials in consideration of heat transfer properties. Furthermore, in this embodiment, the guide fin 50 connects the pair of first cooling fin groups 30, 30 to enable heat transfer. However, the guide fin 50 need only be capable of rectifying the flow of the coolant, and may not have a heat transfer function. In such a case, the guide fin 50 may be provided spaced apart from the pair of first cooling fin groups 30, 30. Note that, to enable heat transfer between the pair of first cooling fin groups 30, 30, the guide fin 50 may be connected to the pair of first cooling fin groups 30, 30, or may be positioned close to the pair of first cooling fin groups 30, 30 with a small gap therebetween.

[0072] Furthermore, the second flow passage 25 is not limited to being formed in a curved shape, and can be formed in various shapes as long as the flow of the coolant is not obstructed. Furthermore, the guide fin 50 provided inside the second flow passage 25 can also be formed in various shapes depending on the shape and size of the second flow passage 25. Furthermore, in the present embodiment, the guide fin 50 is disposed at the center inside the second flow passage 25, but this is not limiting, and the guide fin 50 may be disposed at a position other than the center inside the second flow passage 25 depending on the curvature of the second flow passage 25, etc.

[0073] In this embodiment, the second cooling fin group 40 is arranged in a direction perpendicular to the direction in which the first cooling fin group 30 is arranged so as to enable heat transfer with the first cooling fin group 30, but the oil cooling structure 1 of the present invention is not limited to this. The second cooling fin group 40 may be arranged in a direction intersecting or parallel to the first cooling fin group 30 so as to enable heat transfer.

[0074] In addition, in the present embodiment, the first cooling fin group 30 is provided on the coolant flow path 20 side inside the oil reservoir 10, and the second cooling fin group 40 is provided on the oil reservoir 10 side inside the coolant flow path 20, but the present invention is not limited to this. The first cooling fin group 30 and the second cooling fin group 40 can be arranged in various ways to enable heat transfer depending on the surrounding usage environment.

[0075] In addition, in this embodiment, the coolant flow paths 20 are arranged so that the first flow paths 21 are densely packed upstream of the oil inflow side of the oil reservoir 10 relative to the oil discharge side, but this is not limited thereto, and the first flow paths 21 can be arranged at various densities depending on the oil flow direction, etc. In addition, in this embodiment, the coolant flow paths 20 are arranged below the oil reservoir 10 and also function as an oil cooler, but an oil cooler of a system separate from the oil cooling structure 1 may be provided.

[0076] The above are various embodiments and modifications of the oil cooling structure according to the present invention, but the present invention is not limited to the above-described embodiments and modifications, and it will be readily apparent to those skilled in the art that other embodiments are possible within the scope of the claims and the teachings and spirit of the present invention. [Industrial Applicability]

[0077] The oil cooling structure of the present invention can be used to cool oil in various drive devices of vehicles, etc. Furthermore, the oil cooling structure of the present invention can be preferably used to cool oil that lubricates drive motors, generator motors, engines, transmissions, and various drive gears in electric vehicles, hybrid vehicles, and internal combustion engine vehicles. [Explanation of symbols]

[0078] 1: Oil cooling structure 10: Oil reservoir 15: Connecting wall (bottom wall) 20: Coolant flow path 21: First flow path 25:Second flow path 30: First cooling fin group 31: Finn 40: Second cooling fin group 41: Finn 50: Guide fin

Claims

1. An oil cooling structure for cooling oil for lubricating a drive unit, an oil reservoir disposed within a case that accommodates the drive device; a coolant flow path that is at least partially overlapped with the oil reservoir and is arranged to be heat transferable, and through which a coolant can flow; Equipped with The coolant flow path includes a plurality of first flow paths connected via second flow paths, a first cooling fin group including a plurality of fins arranged in parallel so as to extend along the first flow path is provided inside the first flow path, at least one guide fin is provided inside the second flow path, which is disposed between a pair of the first flow paths adjacent to each other in the flow direction of the cooling liquid, among the plurality of first flow paths, to guide the cooling liquid flowing between the first cooling fin groups in the pair of first flow paths, the oil reservoir has a second cooling fin group consisting of a plurality of fins arranged in parallel, a heat-transferable connecting wall is provided between the first cooling fin group and the second cooling fin group, the first cooling fin group and the second cooling fin group are arranged to at least partially overlap each other via the connecting wall and to be capable of transferring heat, the second cooling fin group is arranged in a direction intersecting with a direction in which the first cooling fin group is arranged so as to enable heat transfer between the second cooling fin group and the first cooling fin group, the second cooling fin group is divided into two groups, an inflow-side second cooling fin group provided on the oil inflow side and an outflow-side second cooling fin group provided on the oil outflow side, and the outflow-side second cooling fin group is disposed at an interval from the inflow-side second cooling fin group, an oil cooling structure characterized in that the coolant flow path is divided into an area where the inlet-side second cooling fin group is arranged and an area where the outlet-side second cooling fin group is arranged, and the divided coolant flow paths are connected by piping.

2. The plurality of first flow paths are connected to each other via the second flow paths so as to turn back in a serpentine manner, The second flow path is formed in a curved shape, The guide fin is curved along the curve of the second flow path and is disposed at a middle portion inside the second flow path, The oil cooling structure according to claim 1 , wherein the second cooling fin group overlaps with the guide fin.

3. 3. The oil cooling structure according to claim 1, wherein the coolant flow path is arranged so that the first flow path is denser upstream of the oil inflow side of the oil reservoir than the oil discharge side.

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