Vehicle drive device

Abstract

To provide a driving device for a vehicle capable of easily utilizing heat of oil stored in an oil storage part.SOLUTION: In vehicle driving device 10, oil storage portion 26 in which oil is stored is formed in a lower portion of case 20, case 20 includes heat transfer suppression portion 40 provided to extend horizontally at a position in upward and downward directions Z based on a height of an oil surface in oil storage portion 26, and heat transfer suppression portion 40 is higher in heat resistance than a portion of case 20 adjacent to an upper Z1 with respect to heat transfer suppression portion 40 and a portion of case 20 adjacent to a lower Z2 with respect to heat transfer suppression portion 40.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device including a rotating electric machine, a power transmission mechanism, and a case for containing oil. [Background technology]

[0002] A vehicle drive device including a rotating electric machine, a power transmission mechanism, and a case that stores oil is known. JP 2020-091001 A (Patent Document 1) discloses a vehicle drive device that includes a rotating electric machine (13), a power transmission device (2), and a case (3) that stores oil, and an oil reservoir (9) that stores oil is formed in a lower part of the case (3). In this vehicle drive device, oil from the oil reservoir (9) is sucked by an oil pump (15) and supplied to the rotating electric machine (13). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-091001 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vehicle drive system of Patent Document 1, oil is drawn from an oil reservoir by an oil pump, cooled in an oil cooler, and then supplied to a rotating electric machine. However, in a vehicle drive system, there are cases where it is desirable to utilize the oil whose temperature has risen due to heat from the rotating electric machine. However, if the temperature of the oil stored in the oil reservoir tends to drop, it is difficult to utilize the heat.

[0005] Therefore, it is desirable to realize a vehicle drive device that can easily utilize the heat of the oil stored in the oil reservoir. [Means for solving the problem]

[0006] The vehicle drive device of the present disclosure is a vehicle drive device comprising a rotating electric machine, an output member drivingly connected to a wheel, a power transmission mechanism that transmits power between the rotating electric machine and the output member, and a case that contains the rotating electric machine, the power transmission mechanism, and oil, wherein an oil reservoir for storing oil is formed in the lower part of the case, and the case comprises a heat conduction suppression portion that is arranged to extend horizontally at a vertical position based on the height of the oil level in the oil reservoir, and the heat conduction suppression portion has a higher thermal resistance than a portion of the case adjacent to the upper side of the heat conduction suppression portion and a portion of the case adjacent to the lower side of the heat conduction suppression portion.

[0007] This configuration prevents the heat of the oil in the oil reservoir from being transferred through the case to the portion of the case above the heat conduction suppressing portion, thereby minimizing the amount of heat dissipated to the outside via the case. This makes it easier to utilize the heat of the oil stored in the oil reservoir. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a vehicle equipped with a vehicle drive device according to a first embodiment; [Figure 2] FIG. 2 is a schematic exploded perspective view of the vehicle drive device of FIG. 1; [Figure 3] A diagram showing the heat conduction suppression section as seen from inside the case of Figure 2. [Figure 4] FIG. 3 is a cross-sectional view of the case in which the heat conduction suppressing portion of FIG. 2 is formed. [Figure 5] FIG. 10 is a diagram showing a heat conduction suppression unit of a vehicle drive device according to a second embodiment. [Figure 6] FIG. 10 is a diagram illustrating a heat conduction suppression portion of a vehicle drive device according to another embodiment; [Figure 7] FIG. 10 is a diagram illustrating a heat conduction suppression portion of a vehicle drive device according to another embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A vehicle drive device 10 according to a first embodiment will be described below with reference to the drawings.

[0010] FIG. 1 is a diagram showing an example of a vehicle 8 equipped with a vehicle drive device 10. The vehicle drive device 10 includes a rotating electric machine MG. The rotating electric machine MG is a driving force source for the vehicle 8. Examples of the vehicle 8 include a hybrid electric vehicle (HEV) equipped with an internal combustion engine and a rotating electric machine, a plug-in hybrid electric vehicle (PHEV), a battery electric vehicle (BEV), and a fuel cell electric vehicle (FCEV). The vehicle 8 may be a three-wheeled vehicle or a four-wheeled vehicle. In this embodiment, the vehicle 8 is a four-wheeled automobile.

[0011] The vehicle drive device 10 includes an output member. The output member is drivingly connected to the wheels (W1, W2). Here, "drivingly connected" refers to a state in which two rotating elements are connected to transmit driving force, including a state in which the two rotating elements are connected to rotate integrally, or a state in which the two rotating elements are connected to transmit driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at variable speeds, such as shafts, gear mechanisms, belts, and chains. Note that transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices. However, when referring to rotating elements of a planetary gear mechanism, the term "drivingly connected" refers to a state in which the rotating elements are drivingly connected without passing through other rotating elements of the planetary gear mechanism. Furthermore, in this specification, "rotating integrally" refers to rotating integrally, regardless of whether the elements are separable or inseparable. That is, the plurality of members that rotate together may be integrally formed from the same member, or may be made of separate members and integrated by welding, spline connection, or the like.

[0012] The wheels include a first wheel W1 and a second wheel W2. In this embodiment, the wheels to which the output member is drivingly connected, i.e., the drive wheels, are a pair of wheels (first wheel W1, second wheel W2) provided on the vehicle 8, but may be two pairs of wheels or may be a single wheel. Examples of the "output member" include the first side gear 15a, the second side gear 15b, their spline engagement portion 15d, the first drive shaft DS1, the second drive shaft DS2, and the connecting shaft 17, which will be described later. In this embodiment, the spline engagement portion 15d is the output member.

[0013] The first wheel W1 is drivingly connected to the first drive shaft DS1, and the second wheel W2 is drivingly connected to the second drive shaft DS2. In this embodiment, the pair of side gears (15a, 15b) that serve as output gears of the differential gear mechanism 15 includes a first side gear 15a and a second side gear 15b. The first side gear 15a is drivingly connected to the first drive shaft DS1 via a connecting shaft 17, and the second side gear 15b is drivingly connected to the second drive shaft DS2. For example, the first side gear 15a and the connecting shaft 17 are connected by a spline connection, and the second side gear 15b and the second drive shaft DS2 are also connected by a spline connection. These connecting portions are spline engagement portions 15d.

[0014] The rotating electric machine MG functions as a driving force source for the wheels (first wheel W1, second wheel W2). The rotating electric machine MG is an inner rotor type rotating electric machine. The rotating electric machine MG includes a stator 11 and a rotor 12 connected to the rotor shaft 13 so as to rotate integrally with the rotor shaft 13. In the following description, the direction along the rotation axis X1 of the rotor 12 is referred to as the "axial direction L." One side of the axial direction L is referred to as the "axial first side L1." The other side of the axial direction L is referred to as the "axial second side L2."

[0015] The stator 11 includes a cylindrical stator core 11a and a coil wound around the stator core 11a. The coil includes coil end portions 11b that protrude outward in the axial direction L from the stator core 11a. The axis of the stator core 11a is the same as the rotation axis X1 of the rotor 12 described above. In this embodiment, the axis of the stator core 11a is the same as the rotation axis X1 of a differential case 15c described below. In this embodiment, the stator 11 is fixed to a case 20 described below.

[0016] The rotor 12 is rotatably disposed radially inward relative to the stator 11. The rotor 12 includes a rotor core 12a and a permanent magnet (not shown) fixed to the rotor core 12a. The rotor shaft 13 is formed in a cylindrical shape coaxial with the rotor core 12a, and a sun gear SG of a planetary gear mechanism constituting the reducer 16 is disposed on the outer circumferential side of the rotor shaft 13 on a first axial side L1 so as to rotate integrally with the rotor shaft 13. In the illustrated example, the rotating electric machine MG is a rotating field type rotating electric machine.

[0017] The direction perpendicular to the rotation axis X1 of the rotor 12 is defined as the "radial direction." In the radial direction, the side of the rotation axis X1 of the rotor 12 is defined as the "radially inner side," and the opposite side is defined as the "radially outer side." When the vehicle drive device 10 is mounted on the vehicle 8, the direction along the vertical direction is defined as the "upper-lower direction Z," with the upper side defined as the "upper side Z1 of the vertical direction Z" and the lower side defined as the "lower side Z2 of the vertical direction Z." When the vehicle drive device 10 is mounted horizontally on the vehicle 8, one of the radial directions coincides with the up-down direction Z. In addition, the direction perpendicular to the axial direction L and the up-down direction Z is defined as the "front-rear direction H," with one side of the front-rear direction H defined as the "first front-rear direction side H1" and the other side defined as the "second front-rear direction side H2." In this embodiment, the first front-rear direction side H1 corresponds to the front side of the vehicle 8, and the second front-rear direction side H2 corresponds to the rear side. The axial direction L corresponds to the "width direction" of the vehicle 8.

[0018] The vehicle drive device 10 includes a power transmission mechanism GT that transmits driving force between the rotating electric machine MG and an output member. The power transmission mechanism GT includes a reduction gear 16 and a differential gear mechanism 15. In this embodiment, the rotating electric machine MG, the reduction gear 16, and the differential gear mechanism 15 are coaxially arranged in the order shown from the second axial side L2 to the first axial side L1. In this embodiment, the shaft on which the rotating electric machine MG, the reduction gear 16, and the differential gear mechanism 15 are arranged, with the rotation axis X1 as its axis, is the rotation axis of the vehicle drive device 10 and also the rotation axis of the rotating electric machine MG, the reduction gear 16, and the differential gear mechanism 15.

[0019] In the vehicle drive device 10 of this embodiment, the rotating shafts of the rotating electric machine MG, the reducer 16, and the differential gear mechanism 15 are coaxial, but the rotating shafts of the rotating electric machine MG and the differential gear mechanism 15 may be configured as two different shafts, or further, the reducer 16 may be configured as three different shafts having a third rotating shaft different from both the rotating shafts of the rotating electric machine MG and the differential gear mechanism 15.

[0020] The reducer 16 is configured as a planetary gear mechanism including an input element that rotates integrally with the rotor shaft 13, a fixed element fixed to a case 20 (described later), an output element that rotates integrally with a differential input element (differential case 15c), and planetary gears. This planetary gear mechanism is a compound planetary gear mechanism that includes one sun gear SG, two ring gears (first ring gear RG1 and second ring gear RG2), two planetary gears that rotate integrally (first planetary gear PG1 and second planetary gear PG2), and a carrier CR that rotatably supports the two planetary gears. In this embodiment, the first planetary gear PG1 has a smaller diameter than the second planetary gear PG2.

[0021] The sun gear SG rotates integrally with the rotor 12 and rotor shaft 13. The second ring gear RG2 is fixed to a case 20, which will be described later. The first ring gear RG1 is disposed on a first axial side L1 relative to the second ring gear RG2 and is connected to the differential case 15c so as to rotate integrally with the differential case 15c. The second planetary gear PG2 meshes with the sun gear SG and the second ring gear RG2, and the first planetary gear PG1 rotates integrally with the second planetary gear PG2 and meshes with the first ring gear RG1.

[0022] The differential gear mechanism 15 is a bevel gear type differential gear mechanism, and includes a bevel gear pinion 15p and a side gear. The side gear includes a first side gear 15a and a second side gear 15b. The pinion 15p is rotatably supported by a pinion shaft 15s that is supported by a differential case 15c and arranged to extend radially. The differential case 15c accommodates the pinion 15p, the first side gear 15a, the second side gear 15b, and the pinion shaft 15s.

[0023] The first side gear 15a is drivingly connected to the first wheel W1 via the connecting shaft 17. The second side gear 15b is connected to rotate integrally with the second drive shaft DS2, which is drivingly connected to the second wheel W2, which is the wheel on the first axial side L1. The first side gear 15a and the second side gear 15b each include a gear portion that meshes with the pinion 15p and a spline engagement portion 15d that is connected to the connecting shaft 17 or the second drive shaft DS2.

[0024] The first side gear 15a is connected to a connecting shaft 17 that passes through the reducer 16 and the radially inner side of the hollow cylindrical rotor shaft 13 and extends along the axial direction L. The connecting shaft 17 is connected to rotate integrally with a first drive shaft DS1 that is drivingly connected to a first wheel W1, which is a wheel on the second axial side L2.

[0025] 2 is a diagram showing an example of an exploded perspective view of the vehicle drive device 10. The vehicle drive device 10 includes a case 20 that contains oil. The case 20 contains a rotating electric machine MG and a power transmission mechanism GT. Examples of materials for the case 20 include metals such as aluminum, titanium, and iron, alloys using these metals, and oil-resistant resins.

[0026] The case 20 includes a first housing chamber E1 and a second housing chamber E2. The first housing chamber E1 houses, for example, an inverter module for driving and controlling the rotating electric machine MG, a power supply module, etc. The second housing chamber E2 houses, for example, the rotating electric machine MG, a power transmission mechanism GT, etc. In this embodiment, the case 20 is integrally formed with the first housing chamber E1, the second housing chamber E2, and a partition wall (not shown) that separates the first housing chamber E1 from the second housing chamber E2.

[0027] The case 20 has a first case portion 21 and a second case portion 22. The first case portion 21 is a portion in which the first storage chamber E1 is formed. In this embodiment, the first storage chamber E1 and the second storage chamber E2 are arranged side by side in the vertical direction Z.

[0028] The first case portion 21 is formed in the shape of a rectangular box that is open on the upper side Z1 in the vertical direction Z when mounted on the vehicle. The first case portion 21 includes a peripheral wall portion 21b that surrounds the first opening 20a and is arranged to extend along the vertical direction Z when mounted on the vehicle. The case 20 includes a first cover 23. The first opening 20a is closed by the first cover 23.

[0029] The second case portion 22 is formed in a cylindrical shape with both sides open in the axial direction L, and includes a cylindrical peripheral wall portion 22b. The cylindrical peripheral wall portion 22b surrounds the power transmission mechanism GT from the radial outside. The opening formed on the second axial side L2 is the second opening portion 20b, and the opening formed on the first axial side L1 is the third opening portion 20c.

[0030] The case 20 includes a second cover 24 and a third cover 25. The second opening 20b is closed by the second cover 24, and the third opening 20c is closed by the third cover 25. The second cover 24 and the third cover 25 are formed with a pair of through holes 20d through which the above-mentioned drive shafts (first drive shaft DS1, second drive shaft DS2) pass.

[0031] An oil reservoir 26 for storing oil is formed in the lower part of the case 20. In this embodiment, the oil reservoir 26 is formed in the second case part 22. An opening 27 for refilling oil into the case 20 is provided on the outer surface of the case 20. The opening 27 is located on the lower side Z2 of the center of the case 20 in the up-down direction Z. In this embodiment, the opening 27 is formed in the second case part 22. The opening 27 is closed by a lid 28.

[0032] The vehicle drive device 10 includes a heat exchanger 32 connected to the oil reservoir 26 and exchanging heat between the oil in the oil reservoir 26 and a heat medium. The oil is cooled by the heat medium in the heat exchanger 32. The heat exchanger 32 may be connected to the oil reservoir 26 via an oil pump 31 (described later), or may be connected directly to the oil reservoir 26. In this embodiment, the heat exchanger 32 is disposed inside the case 20, but may also be disposed outside. In the illustrated example, the heat exchanger 32 is housed in the first housing chamber E1.

[0033] In this embodiment, the vehicle drive system 10 is configured so that the heat medium whose temperature has been increased in the heat exchanger 32 can be supplied to a heating device, a battery, etc. In this way, the heat of the heat medium can be used to warm the battery and heat the cabin in cold weather, etc. In this embodiment, examples of the heat exchanger 32 include an oil cooler, an air conditioner, a heating device, etc. The heat medium may be a liquid or a gas. Examples of the "heat medium" include antifreeze, water, oil, fluorocarbon, etc.

[0034] The vehicle drive device 10 includes an oil pump 31 connected to a heat exchanger 32 and configured to pump up oil from the oil reservoir 26. The oil pump 31 may be disposed inside or outside the case 20. The oil pump 31 may be connected to the oil reservoir 26 such that the oil pumped up from the oil reservoir 26 flows into the oil pump 31 after being cooled in the heat exchanger 32, or may be connected to the oil reservoir 26 such that the oil pumped up from the oil reservoir 26 passes through the oil pump 31 and is then cooled in the heat exchanger 32.

[0035] The case 20 is provided with a heat conduction suppression unit 40 located in the vertical direction Z based on the height of the oil level in the oil reservoir 26. The heat conduction suppression unit 40 suppresses heat conduction at least in the vertical direction Z. Here, heat conduction includes heat transfer within the same material, heat transfer through different materials, and heat transfer through different members. In this embodiment, the heat conduction suppression unit 40 includes a recessed groove formed on at least one of the inner and outer surfaces of the case 20.

[0036] The heat conduction suppression unit 40 is provided on the case 20 so as to extend in the horizontal direction. Extending in the horizontal direction means that the extending direction has a horizontal component, and may extend along a direction inclined relative to the horizontal direction. Also, for example, multiple straight line portions of the heat conduction suppression unit 40 extending in the horizontal direction may be connected by curved or inclined portions. In this embodiment, the heat conduction suppression unit 40 is provided on the case 20 so as to extend only in the horizontal direction. Note that the horizontal direction and the vertical direction Z in the vehicle drive device 10 refer to the horizontal direction and the vertical direction Z when the vehicle 8 on which the vehicle drive device 10 is mounted is on a level road surface.

[0037] In this embodiment, the heat conduction suppressing portion 40 is provided on the case 20 so as to extend horizontally near the oil surface. The heat conduction suppressing portion 40 is formed on each of the surfaces on both sides of the case 20 in the front-to-rear direction H so as to extend in the axial direction L. The heat conduction suppressing portion 40 is formed on each of the surfaces on both sides of the case 20 in the axial direction L so as to extend in the front-to-rear direction H.

[0038] The heat conduction suppressing unit 40 has a higher thermal resistance than a portion of the case 20 adjacent to the upper side Z1 of the heat conduction suppressing unit 40. The heat conduction suppressing unit 40 has a higher thermal resistance than a portion of the case 20 adjacent to the lower side Z2 of the heat conduction suppressing unit 40. Note that there may be a portion above the upper side Z1 of the heat conduction suppressing unit 40 that has a higher or lower thermal resistance than the heat conduction suppressing unit 40 than the portion adjacent to the upper side Z1 of the heat conduction suppressing unit 40, and there may be a portion below the lower side Z2 of the heat conduction suppressing unit 40 that has a higher or lower thermal resistance than the heat conduction suppressing unit 40 than the portion adjacent to the lower side Z2 of the heat conduction suppressing unit 40. The unit of thermal resistance is expressed in °C / W or K / W, for example. High thermal resistance makes it difficult for heat to transfer, and low thermal resistance makes it easy for heat to transfer.

[0039] The heat conduction suppressing portion 40 is formed continuously or intermittently so as to extend in the horizontal direction. In this embodiment, the heat conduction suppressing portion 40 is formed continuously around the entire circumference of the case 20 in the horizontal direction. The heat conduction suppressing portion 40 may be provided so as to extend continuously around the case 20 in the horizontal direction once, or may be provided so as to extend continuously around the case 20 in the horizontal direction two or more times.

[0040] The heat conduction suppression unit 40 is provided at a position below a pair of through holes 20d in the case 20, through which the drive shafts (first drive shaft DS1, second drive shaft DS2) pass. In this embodiment, the heat conduction suppression unit 40 is provided at a position below the rotational axis X1 of the rotor 12 in the vertical direction Z. FIG. 3 is a schematic diagram showing an example of the heat conduction suppression unit 40 as viewed from inside the case 20. In this embodiment, the heat conduction suppression unit 40 is provided at a position below the height S1 of the opening 27 in the vertical direction Z. Lowering the position of the heat conduction suppression unit 40 makes it easier to reduce the range over which heat from the oil in the oil reservoir (26) in the case 20 is conducted.

[0041] The heat conduction suppression unit 40 is provided at a position equal to or higher than the oil level in the oil reservoir 26. In this embodiment, the heat conduction suppression unit 40 is provided at a position equal to or higher than the oil level in the oil reservoir 26. Examples of the oil level in the oil reservoir 26 include the maximum oil level Qmax, the minimum oil level Qmin, the average oil level Qave, the oil level Qmax1 in the oil reservoir 26 when the rotating electric machine MG is stopped, and the oil level Qmin1 in the oil reservoir 26 when the rotating electric machine MG is operating. When the heat conduction suppression unit 40 is provided at a position equal to or higher than the oil level, it is easy to minimize the amount of heat from the oil in the oil reservoir 26 that is dissipated to the outside via the case 20.

[0042] In this embodiment, the heat conduction suppression unit 40 is provided at a position equal to or higher than the height Qmin1 of the oil level in the oil reservoir 26 when the rotating electric machine MG is in operation. In this embodiment, the heat conduction suppression unit 40 is provided in the case 20 so as to extend in the horizontal direction near the height of the oil level in the oil reservoir 26. In this embodiment, the heat conduction suppression unit 40 is provided in the case 20 so as to extend along the oil level.

[0043] 4 is a diagram showing an example of a cross section of the case 20 on which a heat conduction suppressing portion 40 is formed. The heat conduction suppressing portion 40 is formed in a portion of the case 20 in the thickness direction. In this embodiment, the heat conduction suppressing portion 40 is a groove formed on the inner surface of the case 20. However, the heat conduction suppressing portion 40 may also be a groove formed on the outer surface of the case 20. By providing a groove in the case 20, the cross-sectional area of ​​the path of heat conduction in the vertical direction Z can be reduced.

[0044] The depth A1 of the groove is, for example, 20% or more of the thickness of the case 20. Preferably, the depth A1 of the groove is 30% or more of the thickness of the case 20. Increasing the depth A1 of the groove makes it easier to improve the effect of suppressing heat conduction in the vertical direction Z. The thickness of the case 20 is not particularly limited, but is, for example, 1 mm or more and 20 mm or less. In this embodiment, the thickness of the case 20 is approximately 3 mm.

[0045] The depth A1 of the recessed groove is, for example, 80% or less of the thickness of the case 20. Preferably, the depth A1 of the recessed groove is 60% or less of the thickness of the case 20. By making the depth A1 of the recessed groove shallow, it is easy to ensure the strength of the case 20.

[0046] The width A2 of the groove in the vertical direction Z is, for example, 3 mm or more. Preferably, the width A2 of the groove in the vertical direction Z is 5 mm or more. Increasing the width A2 of the groove in the vertical direction Z makes it easier to enhance the effect of suppressing heat conduction in the vertical direction Z. The width A2 of the groove in the vertical direction Z is, for example, 80 mm or less. Preferably, the width A2 of the groove in the vertical direction Z is 50 mm or less. Reducing the width A2 of the groove in the vertical direction Z makes it easier to ensure the strength of the case 20.

[0047] Second Embodiment The following describes a vehicle drive device 10 according to the second embodiment with reference to the drawings. The following description focuses on differences from the first embodiment. Note that points that are not specifically described are the same as those in the first embodiment.

[0048] Fig. 5 is a diagram showing an example of a cross section of the case 20 in which the heat conduction suppressing portion 40 of this embodiment is formed. Fig. 5 is a diagram corresponding to Fig. 4. In this embodiment, the heat conduction suppressing portion 40 includes a pair of grooves formed on both the inner and outer surfaces of the case 20. The pair of grooves are formed on both the inner and outer surfaces of the wall at the same position on the case 20. In this way, the pair of grooves can reduce the wall thickness from both the inside and outside, thereby reducing the cross-sectional area of ​​the path of heat conduction in the vertical direction Z.

[0049] Here, the depth of the groove formed on the inner surface of the case 20 is defined as depth A1a. The depth of the groove formed on the outer surface of the case 20 is defined as depth A1b. The sum of depth A1a and depth A1b is, for example, 10% or more of the thickness of the case 20. Preferably, the sum of depth A1a and depth A1b is 20% or more of the thickness of the case 20. The sum of depth A1a and depth A1b is, for example, 80% or less of the thickness of the case 20. Preferably, the sum of depth A1a and depth A1b is 60% or less of the thickness of the case 20.

[0050] Here, the width in the vertical direction Z of the recessed groove formed on the inner surface of the case 20 is defined as width A2a. Furthermore, the width in the vertical direction Z of the recessed groove formed on the outer surface of the case 20 is defined as width A2b. Each of widths A2a and A2b is, for example, 3 mm or more. Preferably, each of widths A2a and A2b is 5 mm or more. Each of widths A2a and A2b is, for example, 80 mm or less. Preferably, each of widths A2a and A2b is 50 mm or less.

[0051] Other Embodiments Next, other embodiments of the vehicle drive device 10 will be described.

[0052] (1) In the above embodiment, the heat conduction suppressing portion 40 is formed continuously along the entire circumference of the case 20 along the horizontal direction. However, the present invention is not limited to such an example. For example, as shown in FIG. 6 , the heat conduction suppressing portion 40 may be formed intermittently along the entire circumference of the case 20 along the horizontal direction. Furthermore, for example, the heat conduction suppressing portion 40 may be provided only on a portion of the circumference of the case 20 along the horizontal direction. Furthermore, for example, the heat conduction suppressing portion 40 may be formed only on both surfaces of the case 20 in the axial direction L or only on both surfaces of the case 20 in the front-rear direction H. Note that in the example shown in FIG. 6 , the heat conduction suppressing portion 40 may be a recessed groove formed on the outer surface of the case 20.

[0053] (2) In the above embodiment, the heat conduction suppressing portion 40 is formed as a single straight line extending horizontally. However, the present invention is not limited to such an example. For example, as shown in FIG. 7 , the heat conduction suppressing portion 40 may be formed as multiple straight lines extending horizontally. For example, the heat conduction suppressing portion 40 may have a portion formed as a straight line along the vertical direction Z. For example, the heat conduction suppressing portion 40 may have a curved portion. In the example shown in FIG. 7 , the heat conduction suppressing portion 40 is formed so as to avoid a component mounting portion 50 provided on the outer surface of the case 20. In the example shown in FIG. 7 , the heat conduction suppressing portion 40 is two grooves formed on the outer surface. Note that in the example shown in FIG. 7 , the heat conduction suppressing portion 40 may be a groove formed on the inner surface of the case 20.

[0054] (3) In the above embodiment, an example has been described in which the case 20 accommodates the power transmission mechanism GT, the rotating electric machine MG, and the differential gear mechanism 15. However, the present invention is not limited to such an example, and for example, the case 20 does not have to accommodate the differential gear mechanism 15. Furthermore, for example, the case 20 does not have to accommodate the power transmission mechanism GT. Furthermore, for example, the vehicle drive device 10 does not have to include the differential gear mechanism 15. Furthermore, for example, the rotating electric machine MG may be an in-wheel motor.

[0055] (4) In the above embodiment, an example has been described in which the heat conduction suppressing unit 40 is provided at a position equal to or lower than the height of the opening 27 in the vertical direction Z and equal to or higher than the oil level. However, the present invention is not limited to such an example. For example, the heat conduction suppressing unit 40 may be provided at a position slightly lower than the height of the oil level in the vertical direction Z. Furthermore, for example, the heat conduction suppressing unit 40 may be provided at a position slightly higher than the height of the opening 27 in the vertical direction Z.

[0056] (5) In the above embodiment, the heat conduction suppressing portion 40 is a groove formed on at least one of the inner and outer surfaces of the case 20. However, the present invention is not limited to such an example. For example, the heat conduction suppressing portion 40 may be formed of a metal, resin, or the like having a higher thermal resistance than the material of the remaining portions of the case 20. For example, the heat conduction suppressing portion 40 may include a cavity extending horizontally inside the case 20. For example, the heat conduction suppressing portion 40 may include a member such as a metal or resin disposed in the groove or cavity. For example, the heat conduction suppressing portion 40 may be a water channel formed to extend horizontally in a portion of the thickness direction of the case 20.

[0057] (6) In the above embodiment, the vehicle drive system 10 is described as having the heat exchanger 32 and the oil pump 31. However, the present invention is not limited to such an example, and for example, the vehicle drive system 10 may not have the oil pump 31. Furthermore, for example, the vehicle drive system 10 may not have the heat exchanger 32, and the oil reservoir 26 may directly heat the in-vehicle devices, etc.

[0058] (7) The configurations disclosed in the above-described embodiments may be combined with configurations disclosed in other embodiments as long as no contradictions arise. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications may be made as appropriate within the scope of the present disclosure.

[0059] Summary of the above embodiment Hereinafter, a vehicle drive device according to the present disclosure will be described.

[0060] In one aspect, the vehicle drive device (10) includes a rotating electric machine (MG), an output member (spline engagement portion 15d) drivingly connected to wheels (first wheel W1, second wheel W2), a power transmission mechanism (GT) that transmits power between the rotating electric machine (MG) and the output member (spline engagement portion 15d), and a case (20) that contains the rotating electric machine (MG), the power transmission mechanism (GT), and oil, and the case (20) has a lower portion provided with an oil reservoir. The case (20) is provided with a heat conduction suppression part (40) extending horizontally at a vertical (Z) position based on the height of the oil level in the oil reservoir (26), and the heat conduction suppression part (40) has a higher thermal resistance than a part of the case (20) adjacent to an upper side (Z1) of the heat conduction suppression part (40) and a part of the case (20) adjacent to a lower side (Z2) of the heat conduction suppression part (40).

[0061] This configuration can prevent the heat of the oil in the oil reservoir (26) from being transferred through the case (20) to the portion (Z1) of the case (20) above the heat conduction suppression portion (40). This reduces the amount of heat of the oil that is dissipated to the outside through the case (20). This makes it easier to utilize the heat of the oil stored in the oil reservoir (26).

[0062] In one aspect, the heat conduction suppression portion (40) is provided at a position equal to or higher than the height (Qmin1) of the oil surface in the oil reservoir (26) when the rotating electrical machine (MG) is in operation.

[0063] According to this configuration, when the rotating electrical machine (MG) is in operation, it is easy to reduce the area over which the heat of the oil in the oil reservoir (26) is transferred through the case (20), thereby reducing the amount of heat of the oil that is dissipated to the outside through the case (20) when the rotating electrical machine (MG) is in operation.

[0064] In one aspect, the heat conduction suppressing portion (40) includes a recessed groove formed on at least one of the inner surface and the outer surface of the case (20).

[0065] This configuration makes it easy to simplify the configuration of the heat conduction suppression portion (40).

[0066] In one embodiment, the heat conduction suppressing portion (40) is formed continuously along the entire periphery of the case (20) along the horizontal direction.

[0067] This configuration effectively prevents the heat of the oil in the oil reservoir (26) from being transferred to the portion (Z1) above the heat transfer suppressing portion (40).

[0068] In one embodiment, an opening (27) for refilling oil into the case (20) is provided on the outer surface of the case (20), and the heat conduction suppression section (40) is provided at a position that is less than the height (S1) of the opening (27) in the vertical direction (Z) and greater than the height (Qmin1) of the oil level in the oil reservoir section (26) when the rotating electric machine (MG) is operating.

[0069] This configuration makes it easy to minimize the area over which the heat of the oil in the oil reservoir (26) is transferred through the case (20), thereby minimizing the amount of heat of the oil that is dissipated to the outside through the case (20).

[0070] It is sufficient for the vehicle drive device according to the present disclosure to achieve at least one of the above-described effects. [Explanation of symbols]

[0071] 8: vehicle, 10: vehicle drive device, 15d: spline engagement portion (output member), 20: case, 26: oil reservoir, 27: opening, 40: heat conduction suppression portion, GT: power transmission mechanism, MG: rotating electric machine, W1: first wheel (wheel), W2: second wheel (wheel)

Claims

1. A rotating electric machine, an output member drivingly connected to the wheels; a power transmission mechanism that transmits power between the rotating electric machine and the output member; a case that accommodates the rotating electric machine, the power transmission mechanism, and oil; A vehicle drive device comprising: An oil reservoir for storing oil is formed in the lower part of the case, the case includes a heat conduction suppression portion provided to extend horizontally at a vertical position based on the height of the oil level in the oil reservoir, A vehicle drive device, wherein the heat conduction suppression portion has a higher thermal resistance than a portion of the case adjacent to the upper side of the heat conduction suppression portion and a portion of the case adjacent to the lower side of the heat conduction suppression portion.

2. The vehicle drive device according to claim 1 , wherein the heat conduction suppression portion is provided at a position equal to or higher than the height of an oil surface in the oil reservoir when the rotating electric machine is in operation.

3. The vehicle drive device according to claim 1 or 2, wherein the heat conduction suppressing portion includes a recessed groove formed on at least one of an inner surface and an outer surface of the case.

4. The vehicle drive device according to claim 1 or 2, wherein the heat conduction suppressing portion is formed continuously around the entire periphery of the case along the horizontal direction.

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