JP7759902B2 - Oil cooling structure - Google Patents

Description

The present invention relates to an oil cooling structure that cools oil used to lubricate the drive system of a vehicle or the like.

Conventionally, electric vehicles and other electrically powered vehicles are equipped with a drive motor as a drive unit. However, the drive motor has a problem in that output efficiency decreases due to heat generated by coils and other components due to overload. To address this problem, a drive unit for an electric vehicle designed to cool the drive motor has been disclosed (for example, Patent Document 1).

The invention described in the aforementioned Patent Document 1 circulates oil within a case that houses a motor (corresponding to a drive motor), and the circulating oil is cooled by a heat exchange plate. Furthermore, the invention described in the aforementioned Patent Document 1 is also equipped with a water-cooled chamber defined on the outside of the heat exchange plate.

Japanese Patent Application Laid-Open No. 2001-251814

Recently, in response to demands for smaller vehicles, drive motors are being housed within the transaxle, and lubrication and cooling of the transaxle along with the drive motor is also required. Therefore, there is a demand for even greater improvements in cooling efficiency.

The present invention aims to provide an oil cooling structure that can uniformly cool oil by equalizing the temperature of the coolant, thereby improving cooling efficiency.

(1) The oil cooling structure of the present invention, provided to solve the above-mentioned problems, is an oil cooling structure for cooling oil for lubricating a drive unit, and includes an oil reservoir disposed within a case that houses the drive unit, and a coolant flow path that overlaps at least partially with the oil reservoir, is arranged to allow heat transfer, and allows coolant to pass through. The coolant flow path is characterized in that a plurality of first flow paths are connected via second flow paths, and a first cooling fin group is provided within the first flow path, with a plurality of fins arranged in parallel and extending along the first flow path, and at least one guide fin is provided within the second flow path, which is disposed between a pair of first flow paths adjacent to each other in the flow direction of the coolant, to guide the coolant flowing between the first cooling fin groups in the pair of first flow paths.

The above-described oil cooling structure has multiple first flow paths connected via second flow paths. Among the multiple first flow paths, at least one guide fin is provided inside a second flow path located between a pair of adjacent first flow paths in the coolant flow direction, guiding the coolant flowing between the first cooling fin groups in the pair of first flow paths. In other words, the guide fin is located between a pair of adjacent first cooling fin groups in the coolant flow direction and guides (rectifies) the coolant flowing between the pair of first cooling fin groups. Therefore, the above-described oil cooling structure allows the coolant to flow smoothly within the coolant flow path. Therefore, the above-described oil cooling structure can equalize 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 improve cooling efficiency. Because the above-described oil cooling structure can improve cooling efficiency, it is expected that the oil cooling structure can be made more compact.

The coolant used here may be, for example, cooling water or an antifreeze such as ethylene glycol. Furthermore, the oil cooling structure described above uses guide fins to connect or closely arrange (with a small gap between) a pair of the first cooling fin groups so that heat can be transferred between them, thereby enabling heat exchange between the pair of first cooling fin devices. Therefore, the oil cooling structure described above is expected to further improve cooling efficiency and enable further miniaturization of the oil cooling structure.

(2) The oil cooling structure of the present invention described above may be characterized in that the multiple first flow paths are connected via the second flow paths in a serpentine manner, 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.

The above-described oil cooling structure, with its configuration, allows oil to flow smoothly along the curved (radial) guide fins. This allows the above-described oil cooling structure to uniformly maintain the temperature of the coolant within the coolant flow path, further improving cooling efficiency. Furthermore, by connecting or arranging a pair of adjacent first cooling fin groups in the coolant flow direction via the guide fins, the pair of first cooling fin groups can transfer heat to each other via the guide fins, 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. This is expected to further improve cooling efficiency with the above-described oil cooling structure.

(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 enable heat transfer between them.

By configuring the oil cooling structure described above, heat can be transferred (heat exchanged) evenly and quickly between the first cooling fin group and the second cooling fin group. This allows the oil cooling structure described above to improve oil cooling efficiency.

(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 to straddle 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 to enable heat transfer between them.

By configuring the oil cooling structure described above, heat can be transferred (heat exchanged) evenly and quickly between the first cooling fin group and the second cooling fin group. This allows the oil cooling structure described above to improve oil cooling efficiency.

(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.

By configuring the oil cooling structure described above, heat can be transferred (heat exchanged) evenly and quickly between the first cooling fin group and the second cooling fin group. This allows the oil cooling structure described above to improve oil cooling efficiency.

(6) 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, 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.

The oil cooling structure described above can transfer heat (heat exchange) via a connecting wall provided between the first cooling fin group and the second cooling fin group. Furthermore, because the oil cooling structure described above has a connecting wall, the connecting wall can be made part of the fins. This allows the oil cooling structure described above to improve its 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 oil cooling efficiency and enable the oil cooling structure to be made more compact.

(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 between the second cooling fin group and the first cooling fin group.

The above-described oil cooling structure, by being configured in this manner, allows the fins in the first cooling fin group and the second cooling fin group to come into direct or indirect contact with each other. Therefore, the above-described oil cooling structure is able to uniformly and quickly exchange heat between the first cooling fin group and the second cooling fin group. This allows the above-described oil cooling structure to uniformly and quickly cool the oil.

(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 between the second cooling fin group and the first cooling fin group.

The above-described oil cooling structure, by being configured in this manner, allows the fins in the first cooling fin group and the second cooling fin group to come into 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 perform oil cooling more uniformly and quickly.

(9) 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, the oil reservoir and the coolant flow path may be arranged adjacent to each other, the first cooling fin group may be provided on the coolant flow path side inside the oil reservoir, and the second cooling fin group may be provided on the oil reservoir side inside the coolant flow path.

The above-described oil cooling structure, with its configuration, allows the first and second cooling fin groups to be arranged in close proximity, 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 coolant flow path are exposed to heat generated by the engine, drive motor, etc., as in the case where the oil reservoir and coolant flow path are installed in the engine compartment of a vehicle, the above-described oil cooling structure can reduce the effects of that heat.

(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.

The above-mentioned oil cooling structure, by being configured in this way, can efficiently cool oil that has been used for lubrication and has generated heat. In other words, the above-mentioned oil cooling structure allows low-temperature coolant to act closely on oil that has been used for lubrication and has become hot, thereby enabling efficient heat exchange.

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

By adopting this configuration, the oil cooling structure described above 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 oil cooling structure described above can reduce the size of the drive unit (including the transaxle).

(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.

The above-mentioned oil cooling structure, by being configured in this way, can efficiently cool the drive motor and generator motor, thereby preventing a decrease in the drive motor's output and a decrease in the generator motor's power generation efficiency.

The present invention provides an oil cooling structure that can uniformly cool oil by equalizing the temperature of the coolant, thereby improving cooling efficiency.

1 is a partially cutaway perspective view of an oil cooling structure according to an embodiment of the present invention; 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. FIG. 3 is a bottom view of FIG. 2 . 3 is a cross-sectional view taken along the line AA in FIG. 2. 3 is a cross-sectional view taken along the arrows BB in FIG. 2.

The 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. Similar components within the drawings are designated by similar reference numerals. It should also be noted that hatching representing cross sections has been omitted in Figures 4 and 5. This embodiment will be described using as an example a case in which the oil cooling structure 1 is used in a transaxle in an electric vehicle.

As shown in Figures 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 group of cooling fins 30 provided inside the coolant flow path 20 and a second group of cooling fins 40 provided inside the oil reservoir 10. In this embodiment, the oil cooling structure 1 has the coolant flow path 20 located below the oil reservoir 10.

The oil reservoir 10 is attached to the lower side of the transaxle (corresponding to the drive unit, not shown). The oil reservoir 10 is designed 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.

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

As shown in Figure 2, the oil reservoir 10 is rectangular in 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 connecting wall 15 (also referred to as bottom wall 15), which will be described later. The case of the oil reservoir 10 is formed by casting or the like using a metal such as aluminum or iron as a material.

An oil outlet 11 is provided on the oil outflow side of the bottom wall 15 of the oil reservoir 10. A second cooling fin group 40 made up of multiple fins 41 is also provided inside the oil reservoir 10.

In this embodiment, the second cooling fin group 40 is divided into two groups, one on the oil inlet side and one on the oil outlet side. For ease of explanation, the second cooling fin group 40 on the oil inlet side may be referred to as the inlet-side second cooling fin group 40R, and the second cooling fin group 40 on the oil outlet side may be referred to as the outlet-side second cooling fin group 40L.

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 multiple fins 41 on the connecting wall 15 so that they are parallel to the left-right direction in the figure. That is, the inlet-side second cooling fin group 40R has multiple fins 41 erected in parallel along the direction from upstream to downstream in the oil flow. This allows the oil to be smoothly discharged from the inlet side to the outlet side. As shown in Figures 1 and 4, the fins 41 are formed from rectangular plate-shaped members. Furthermore, the fins 41 are formed from a metal with good heat exchange properties, such as aluminum, to ensure smooth heat exchange.

The second outlet-side cooling fin group 40L is spaced apart from the second inlet-side cooling fin group 40R. The second outlet-side cooling fin group 40L is rectangular 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 in the left-right direction in the figure. As will be described in detail later, the second cooling fin group 40 is arranged in a direction intersecting (orthogonal in this embodiment) the direction in which the first cooling fin group 30 is arranged 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 and fixed to the connecting wall 15.

The oil discharge port 11 is located 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, etc.

As shown in FIG. 3 , the coolant flow path 20 is configured such that a pair of adjacent first flow paths 21, 21 in the coolant flow direction (left-right direction in the figure) are connected in a serpentine (also called zigzag) shape via a second flow path 25 to form a single flow path. The coolant flow path 20 is capable of passing through it. Examples of the coolant used here include cooling water and antifreeze such as ethylene glycol.

The coolant flow path 20 is positioned so that it at least partially overlaps the oil reservoir 10 and allows heat transfer. In this embodiment, the coolant flow path 20 is positioned so that it overlaps both the area where the inlet-side second cooling fin group 40R is arranged and the area where the outlet-side second cooling fin group 40L is arranged. Specifically, the coolant flow path 20 is divided into the area where the inlet-side second cooling fin group 40R is arranged and the area where the outlet-side second cooling fin group 40L is arranged, and the divided coolant flow paths 20, 20 are connected by piping 22.

The coolant flow path 20 is formed on the back side of the connecting wall 15 that forms the bottom wall 15 of the oil reservoir 10. In other words, 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 coolant to prevent them from mixing.

As shown in Figure 3, the coolant flow path 20 has multiple first flow paths 21 and second flow paths 25 that are located between the multiple first flow paths 21 and connect the multiple first flow paths 21 as a single serpentine (also called zigzag) flow path.

The first flow paths 21 are formed linearly and are arranged in parallel with a gap between them in the direction of coolant flow. In this embodiment, the first flow paths 21 are arranged so that they are 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 oil that has been used for lubrication and generated heat. In other words, the oil cooling structure 1 described above allows low-temperature coolant to act closely on oil that has been used for lubrication and has become hot, thereby efficiently transferring heat (heat exchanging). Note that the first flow paths 21 are not limited to being formed linearly; they can be formed in various shapes (e.g., S-shape) as long as they do not impede the flow of coolant.

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 second cooling fin group 40 described above, so detailed description will be omitted.

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). Furthermore, the multiple fins 31 of the first cooling fin group 30 are erected (hanging) from the underside 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, enabling heat transfer. 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, enabling heat transfer (see FIG. 2).

The oil cooling structure 1 described above therefore allows for uniform heat transfer (heat exchange) between the first cooling fin group 30 and the second cooling fin group 40. Specifically, the multiple fins 31 that make up the first cooling fin group 30 and the multiple fins 41 that make up the second cooling fin group 40 come into direct or indirect contact with each other, thereby allowing for uniform and rapid heat exchange between the first cooling fin group 30 and the second cooling fin group 40. This allows the oil cooling structure 1 described above to increase the oil cooling efficiency.

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

By adopting this configuration, the oil cooling structure 1 described above can reduce the effects of heat generated by the engine, drive motor, etc., even when the outside of the oil reservoir 10 and coolant flow path 20 are exposed to heat generated by the engine, drive motor, etc. Furthermore, because the first cooling fin group 30 and the second cooling fin group 40 are arranged in close proximity to each other, the oil cooling structure 1 described above can efficiently exchange heat between the oil and the coolant. As a result, the oil cooling structure 1 described above can improve the oil cooling efficiency.

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).

A guide fin 50 is provided inside the second flow path 25, which is located between a pair of adjacent first flow paths 21 in the direction of coolant flow.

The guide fin 50 is designed to guide (rectify) 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 thermal conductivity, such as aluminum, into a curved shape along the second flow path 25. The guide fin 50 is positioned midway (preferably in the center) inside the second flow path 25.

The guide fins 50 are also configured to connect a pair of adjacent first cooling fin groups 30, 30 in the coolant flow direction so that heat can be transferred between them. This allows heat exchange between the pair of adjacent first cooling fin groups 30, 30 in the coolant flow direction. Therefore, the oil cooling structure 1 described above is expected to further improve cooling efficiency and enable further miniaturization of the oil cooling structure 1. Note that the guide fins 50 do not have to connect the pair of first cooling fin groups 30, 30 together; they may also be positioned closely spaced apart to allow heat transfer.

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 explained.

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 located 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 located 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 cooling efficiency, which is expected to enable the oil cooling structure 1 to be made smaller. In this embodiment, the first cooling fin group 30 is not provided downstream of the second flow path 25 (the rightmost side in Figure 3), but the first cooling fin group 30 may be provided inside the second flow path 25.

In addition, in the above-described oil cooling structure 1, the second flow path 25 is formed in a curved shape, and the guide fin 50 is curved along the curve of the second flow path 25 and positioned midway within the second flow path 25. Therefore, the above-described oil cooling structure 1 can smoothly rectify the oil along the curved (radial) guide fin 50. As a result, the above-described oil cooling structure 1 can uniform the temperature of the coolant in the coolant flow path 20, thereby further improving cooling efficiency. Furthermore, by connecting or arranging a pair of first cooling fin groups 30, 30 adjacent to each other in the coolant flow direction via the guide fin 50, the pair of first cooling fin groups 30, 30 can transfer heat to each other 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. This is expected to further improve the cooling efficiency of the above-described oil cooling structure 1. The guide fin 50 may be positioned so as to straddle the first cooling fin group 30.

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.

The oil cooling structure 1 described above can therefore 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 oil cooling structure 1 described above has the connecting wall 15, the connecting wall 15 can be used as part of the fins. This allows the oil cooling structure 1 described above 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 oil cooling structure 1 described above 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 enable the oil cooling structure 1 to be made more compact.

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 in the first cooling fin group 30 and the second cooling fin group 40 more uniformly and quickly. This allows the above-described oil cooling structure 1 to cool the oil more uniformly and quickly. The second cooling fin group 40 does not have to overlap with the first cooling fin group 30, but may also overlap with the guide fin 50.

Furthermore, the above-described oil cooling structure 1 can function as an oil cooler because the coolant flow path 20 is located 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).

Furthermore, when the drive device is a drive motor or a generator motor in a vehicle, the above-described oil cooling structure 1 can efficiently cool the drive motor and the generator motor, thereby preventing a decrease in the drive motor's output and a decrease in the generator motor's power generation efficiency.

The above describes 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.

In this embodiment, the drive unit is illustrated as 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 a generator motor, inverter, engine, etc. Furthermore, various drive sources can be used for the drive unit, not just transaxles, such as drive motors, generator motors, engines, etc., either individually or in combination.

The oil reservoir 10 can be of various shapes and sizes, not just the one described in the embodiment. While this embodiment uses ATF, which lubricates the transaxle, as an example of the oil to be cooled, 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. While this embodiment uses the bottom wall 15 (connecting wall 15) of the oil reservoir 10 as the coolant flow path 20, the coolant flow path 20 is not limited to this and can be formed in various configurations, 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 the structure may not even have a connecting wall 15. The connecting wall 15 does not have to be shared with the bottom wall 15 of the oil reservoir 10; it may be provided separately from the bottom wall 15, or on a side wall other than the bottom wall 15, or in various other locations.

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, 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.

Furthermore, the second cooling fin group 40 is not limited to the shape and size of the embodiment described above, and can be formed in various shapes and sizes depending on the shape and size of the oil reservoir 10. Furthermore, in this embodiment, the second cooling fin group 40 is divided into an inlet-side second cooling fin group 40R and an outlet-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.

In addition, in this embodiment, the first cooling fin group 30 and the second cooling fin group 40 are formed from the same fins 31, 41. However, the fins 31, 41 that form the first cooling fin group 30 and the second cooling fin group 40 may be formed from different materials, for example, taking heat transfer properties into consideration. The guide fin 50 can also be formed from various materials, taking heat transfer properties into consideration. In addition, 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, if the pair of first cooling fin groups 30, 30 are to be heat transferable, the guide fin 50 may be connected to the pair of first cooling fin groups 30, 30, or the guide fin 50 may be positioned close to the pair of first cooling fin groups 30, 30 with a small gap between them.

The second flow path 25 is not limited to being curved, and can be formed in various shapes as long as it does not impede the flow of coolant. The guide fin 50 provided inside the second flow path 25 can also be formed in various shapes depending on the shape and size of the second flow path 25. While the guide fin 50 is positioned in the center of the second flow path 25 in this embodiment, this is not limited thereto, and the guide fin 50 may be positioned other than in the center of the second flow path 25 depending on the curvature of the second flow path 25, etc.

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.

In addition, in this embodiment, a configuration has been illustrated in which 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.

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 to this, 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 separate from the oil cooling structure 1 may also be provided.

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. Those skilled in the art will readily understand that other embodiments are possible within the scope of the claims and the teachings and spirit of the present invention.

The oil cooling structure of the present invention can be used to cool oil in various drive systems 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.

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: Fin 40: Second cooling fin group 41: Fin 50: Guide fin

Claims (3)

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 . 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. 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.