Vehicle drive unit

Abstract

Disclosed is a vehicular drive device comprising: a transmission mechanism that transmits a driving force from a drive source to a wheel via a shaft member; and a case that houses the transmission mechanism, and at least a portion of the shaft member. The case includes a gear case part in which an oil that can be lifted up by rotation of a gear of the transmission mechanism accumulates, and a wall part that borders at least a lower side of a space around the shaft member, and extends along an extending direction of the shaft member. The space around the shaft member communicates with the inside of the gear case part, on one side in the extending direction of the shaft member, and includes an object placement space in which an object to be lubricated by the oil is disposed, or communicates with the object placement space, on the other side. The oil lifted up by the rotation of the gear of the transmission mechanism is supplied to the object to be lubricated in the space around the shaft member, or to the object to be lubricated, via the space around the shaft member.

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle drive device. [Background technology]

[0002] A known technology includes a case that defines a first housing chamber that houses a rotating electric machine and a second housing chamber that houses a transmission mechanism, and in which oil that accumulates in the lower part of the second housing chamber is scooped up by the rotation of the gears of the transmission mechanism and supplied to various bearings of the transmission mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-112052 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology described above, the oil scooped up by the rotation of the gears of the transmission mechanism is not used to lubricate the end of the shaft member (for example, the end of an intermediate shaft connected to a differential gear mechanism that is farther from the differential gear mechanism).

[0005] Therefore, in one aspect, an object of the present disclosure is to supply oil scooped up by the rotation of gears in a transmission mechanism to an end of a shaft member. [Means for solving the problem]

[0006] In one aspect, the vehicle includes a transmission mechanism that transmits a driving force from a driving source to a wheel via a shaft member; a case that accommodates the transmission mechanism and at least a portion of the shaft member, The case is a gear case portion in which oil that can be scooped up by rotation of the gears of the transmission mechanism accumulates; a wall portion that bounds at least a lower side of a space around the shaft member and extends along an extension direction of the shaft member; The space around the shaft member has one side in the extension direction of the shaft member communicating with the inside of the gear case portion, and the other side containing an object arrangement space in which an object to be lubricated by oil is arranged or communicating with the object arrangement space, A vehicle drive device is provided in which oil scooped up by the rotation of the gears of the transmission mechanism is supplied to the object to be lubricated in the space around the shaft member or to the object to be lubricated via the space around the shaft member. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, oil scooped up by the rotation of the gears of the transmission mechanism can be supplied to the end of the shaft member. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic top view showing a state in which a vehicle drive device is mounted in a vehicle. [Figure 2] FIG. 2 is a cross-sectional view of the vehicle drive device. [Figure 2A] FIG. 1 is a skeleton diagram showing a vehicle drive device. [Figure 3] 1 is a side view schematically showing a vehicle drive device according to the present embodiment as viewed from the A1 side. [Figure 4] FIG. 2 is a perspective view of a flow path forming member. [Figure 5] FIG. 3 is an enlarged view of part Q6 in FIG. 2. [Figure 6] 2 is a side view schematically showing the vehicle drive device according to the present embodiment as viewed from the A2 side. FIG. [Figure 7] 2 is a perspective view showing the vehicle drive device according to the present embodiment as viewed from the A2 side. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not intended to limit the scope of the invention. In addition, shapes and the like in the drawings may be partially exaggerated for the sake of explanation.

[0010] In the following description, the Y direction (see FIG. 3, etc.) corresponds to the up-down direction of the vehicle drive device 100 when in use, i.e., the up-down direction when the vehicle drive device 100 is oriented in its use state. The Y1 side and Y2 side correspond to the upper and lower sides along the Y direction. Note that the up-down direction does not necessarily have to be parallel to the vertical direction, as long as it has a predominantly vertical component. Furthermore, the directions of each component in the following description refer to the directions when the component is assembled to the vehicle drive device 100. Furthermore, terms related to the dimensions, arrangement direction, arrangement position, etc. of each component are concepts that include differences due to errors (errors within manufacturing tolerances). The A direction (see FIG. 2, etc.) corresponds to the axial direction, and in FIG. 2, etc., the A1 side and the A2 side along the A direction are defined. The X direction (see FIG. 3, etc.) is a direction perpendicular to both the A direction and the Y direction, and in FIG. 3, etc., the X1 side and the X2 side along the X direction are defined.

[0011] In this specification, "driving connection" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force (synonymous with torque), and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members (e.g., shafts, gear mechanisms, belts, chains, etc.) that transmit rotation at a constant speed or at variable speeds. Note that the transmission members may also include engagement devices (e.g., friction engagement devices, meshing engagement devices, etc.) that selectively transmit rotation and driving force.

[0012] In addition, in this specification, "communication" refers to a state in which two spatial elements are fluidly connected to each other. In other words, it refers to a state in which a fluid can pass between the two spatial elements. In this case, the two spatial elements may be directly connected to each other, or may be indirectly connected to each other (i.e., via another spatial element).

[0013] In this specification, the term "rotating electric machine" is used to refer to a motor (electric motor), a generator (electric generator), and a motor-generator that functions as both a motor and a generator as needed. Furthermore, in this specification, with respect to the arrangement of two components, "overlapping when viewed in a specific direction" means that when an imaginary line parallel to the line of sight is moved in each direction perpendicular to the imaginary line, there is at least a region where the imaginary line intersects with both of the two components. Furthermore, in this specification, with respect to the arrangement of two components, "their arrangement regions in a specific direction overlap" means that the arrangement region of one component in a specific direction includes at least a portion of the arrangement region of the other component in a specific direction.

[0014] Fig. 1 is a schematic top view showing a state in which a vehicle drive device 100 is mounted in a vehicle VC. Fig. 2 is a cross-sectional view of the vehicle drive device 100. Fig. 2A is a skeleton diagram showing the vehicle drive device 100.

[0015] As shown schematically in FIG. 2A, the vehicle drive device 100 includes a rotating electric machine 1, a pair of output members 6 drivingly connected to a pair of wheels W (see FIG. 1), and a transmission mechanism 3 that transmits driving force between the rotating electric machine 1 and the pair of output members 6. The vehicle drive device 100 further includes a case 2 that houses the rotating electric machine 1. The case 2 also houses the pair of output members 6 and the transmission mechanism 3. In a modified example, the case 2 may house only one of the pair of output members 6 (for example, the first output member 61). The vehicle drive device 100 is applicable to any vehicle that has a rotating electric machine 1, such as an electric vehicle or a hybrid vehicle, and is applicable to any vehicle with a drive system such as front-wheel drive or rear-wheel drive. The drive source may be an engine (internal combustion engine) only.

[0016] The first output member 61, which is one of the pair of output members 6, is drivingly connected to the first wheel W1, which is one of the pair of wheels W, and the second output member 62, which is the other of the pair of output members 6, is drivingly connected to the second wheel W2, which is the other of the pair of wheels W. As shown in FIG. 1 , a vehicle VC on which the vehicle drive device 100 is mounted includes a first drive shaft 63 that rotates integrally with the first wheel W1 and a second drive shaft 64 that rotates integrally with the second wheel W2. The first drive shaft 63 is connected to the first wheel W1 via, for example, a constant velocity joint, and the second drive shaft 64 is connected to the second wheel W2 via, for example, a constant velocity joint. The first output member 61 is connected to the first drive shaft 63 so as to rotate integrally therewith, and the second output member 62 is connected to the second drive shaft 64 so as to rotate integrally therewith. Note that the first output member 61 may be in the form of an intermediate shaft. The first output member 61 is rotatably supported on the axial direction A2 side relative to the case 2 via a bearing BR1, and is rotatably supported on the axial direction A1 side relative to the case 2 via a bearing BR2. In this embodiment, as an example, the bearings BR1 and BR2 are in the form of ball bearings, but they may be in other forms.

[0017] The vehicle drive device 100 transmits the output torque of the rotating electric machine 1 to a pair of wheels W via a pair of output members 6, thereby running the vehicle VC on which the vehicle drive device 100 is mounted. In other words, the rotating electric machine 1 is a driving force source for the pair of wheels W. The pair of wheels W is a pair of left and right wheels of the vehicle VC (for example, a pair of left and right front wheels or a pair of left and right rear wheels). The rotating electric machine 1 may be, for example, an AC rotating electric machine driven by three-phase AC.

[0018] As shown in FIG. 2, the rotating electric machine 1 and the pair of output members 6 are arranged on two parallel axes (specifically, a first axis C1 and a second axis C2). Specifically, the rotating electric machine 1 is arranged on the first axis C1, and the pair of output members 6 are arranged on a second axis C2 different from the first axis C1. The first axis C1 and the second axis C2 are axes (virtual axes) arranged parallel to each other. The transmission mechanism 3 includes an output gear (ring gear) 30 drivingly connected to at least one of the pair of output members 6, coaxially with the pair of output members 6 (i.e., on the second axis C2).

[0019] The rotating electrical machine 1 is, for example, an inner rotor type. In the rotating electrical machine 1, a rotor 14 that is rotatable about a first axis C1 is disposed radially inside a stator 11 (see FIG. 2).

[0020] The transmission mechanism 3 includes a reduction gear mechanism 34 in a power transmission path between the rotating electric machine 1 and the output gear 30. The reduction gear mechanism 34 is optional and may include a reduction gear mechanism using a counter gear, a reduction gear mechanism using a planetary gear, or the like. In this embodiment, as an example, the reduction gear mechanism 34 includes a planetary gear mechanism, and is disposed coaxially with the rotating electric machine 1. An output gear (carrier) 342 of the reduction gear mechanism 34 radially meshes with the output gear 30 of the differential gear mechanism 5. Such a vehicle drive device 100 can have a compact configuration consisting of two shafts (a first shaft C1 and a second shaft C2). In a modified example, the vehicle drive device 100 may have three or more shafts.

[0021] In this embodiment, the reduction mechanism 34 is arranged coaxially with the rotating electric machine 1 (i.e., on the first axis C1) in a manner that the reduction mechanism 34 is drivingly connected to the rotating electric machine 1. In this embodiment, as an example, the rotor 14 of the rotating electric machine 1 rotates integrally with the input member 16 together with the sun gear 341 of the reduction mechanism 34.

[0022] The transmission mechanism 3 further includes a differential gear mechanism 5. The differential gear mechanism 5 distributes the driving force transmitted from the rotating electric machine 1 to a pair of output members 6. In the example shown in FIG. 2 , the differential gear mechanism 5 distributes the rotation of the output gear 30 to a first side gear 51 and a second side gear 52. The differential gear mechanism 5 may be arranged coaxially with the pair of output members 6 (i.e., on the second axis C2). The differential gear mechanism 5 may be a bevel gear type differential gear mechanism, and the output gear 30 may be connected to a differential case portion 50 included in the differential gear mechanism 5 so as to rotate integrally with the differential case portion 50.

[0023] Next, the water-cooling structure of the rotary electric machine 1 according to this embodiment and its related components (flow path forming member 90, etc.) will be described with reference to FIG. 3 and subsequent figures.

[0024] Fig. 3 is a side view schematically showing a vehicle drive device 100 according to this embodiment. In Fig. 3, the motor cover member 201 is omitted so that the state inside the motor housing chamber S1 can be seen. In Fig. 3, the inverter device 70 inside the inverter case portion 24 is also schematically shown by dotted lines. Fig. 4 is a perspective view of a flow path forming member 90.

[0025] The water-cooling structure of the rotating electric machine 1 according to this embodiment is a structure for cooling the rotating electric machine 1 with cooling water. The cooling water may be water containing LLC (Long Life Coolant), for example, and may be circulated by a water pump (not shown). A heat dissipation unit such as a radiator (not shown) may be provided in the cooling water circulation path. The cooling water may be used not only to cool the rotating electric machine 1, but also to cool other components, such as an inverter (not shown) electrically connected to the rotating electric machine 1.

[0026] The water-cooling structure of the rotating electrical machine 1 according to this embodiment includes a coolant supply portion 40, a coolant discharge portion 42, and a flow path forming member 90.

[0027] The coolant supply unit 40 is connected to the discharge side of a water pump (not shown), for example, and supplies cooling water to the coolant flow path 300 formed by the flow path forming member 90.

[0028] The coolant discharge portion 42 is connected to the suction side of, for example, a water pump (not shown), and supplies (discharges) the cooling water from the coolant flow path 300 formed by the flow path forming member 90 to the water pump (not shown).

[0029] The refrigerant supply unit 40 and the refrigerant discharge unit 42 may be provided above and below the first output member 61. In this case, the space around the first output member 61 can be effectively utilized to provide the refrigerant supply unit 40 and the refrigerant discharge unit 42.

[0030] 4, the flow path forming member 90 has a cylindrical shape with an inner circumferential surface that faces the outer circumferential surface of the rotating electric machine 1 in the radial direction. The flow path forming member 90 forms a refrigerant flow path 300 around the rotating electric machine 1. In the example shown in FIG. 4, the refrigerant flow path 300 has multiple flow path portions SC1 to SC4 in the circumferential direction, but the configuration of the refrigerant flow path 300 is arbitrary.

[0031] The flow path forming member 90 may be made of a material with good thermal conductivity, such as aluminum. In this embodiment, as an example, the flow path forming member 90 is fitted to the stator core 12 of the stator 11 by, for example, shrink fitting. Note that in other embodiments, the flow path forming member 90 may be formed integrally with the stator core 12 by, for example, cast-in insert molding.

[0032] In this embodiment, the flow path forming member 90 is, for example, in the form of an inner case that is fastened to the case 2, as shown in Fig. 3. In this case, the flow path forming member 90 may have a plurality of fastening portions 500 at one axial end side, as shown in Fig. 3. The plurality of fastening portions 500 are fastened to the case 2 by bolts (not shown) (see bolt holes BT4). In a modified example, the flow path forming member 90 may be formed as a part of the case 2.

[0033] The flow path forming member 90 is inserted into the cylindrical space of the case 2. At this time, the outer peripheral surface of the flow path forming member 90 faces radially against the inner peripheral surface of the case 2 (the inner peripheral surface that bounds the multiple fastening portions 500). Note that, hereinafter, the inner peripheral surface of the case 2 that surrounds the flow path forming member 90 in this manner will also be referred to as the "flow path forming surface 209 of the case 2" (see FIG. 5). Note that the inner diameter of the flow path forming surface 209 of the case 2 may be a constant value that is larger than the basic outer diameter of the stator core 12 by the basic thickness of the flow path forming member 90.

[0034] The flow path forming member 90 cooperates with the flow path forming surface 209 of the case 2 to form the refrigerant flow path 300. Specifically, the refrigerant flow path 300 is formed between the outer peripheral surface of the flow path forming member 90 and the flow path forming surface 209 of the case 2 in the radial direction.

[0035] The coolant flow passage 300 may extend in the circumferential direction so that the coolant flows in the circumferential direction over the entire circumferential direction. The coolant flow passage 300 may be formed so as to face the outer peripheral surface of the stator core 12 in the radial direction over the entire axial direction of the stator core 12 of the rotating electric machine 1. The coolant flow passage 300 is closed at both axial ends. For example, seal members 97 (see FIG. 5) may be provided between the flow passage forming member 90 and the flow passage forming surface 209 of the case 2 over the entire circumferential direction at both axial ends of the flow passage forming member 90.

[0036] Next, the oil passage structure and related components of the vehicle drive system 100 according to this embodiment will be described with reference to Figures 5 and subsequent figures. Unless otherwise specified, the various oil passages according to the oil passage structure described below are formed by the case 2. In this specification, the various oil passages formed by the case 2 are a concept that includes not only oil passages formed by the case 2 alone, but also oil passages formed by combining the case 2 with other components (components other than the case 2). In addition, an accommodation chamber such as the output shaft accommodation chamber S3 also constitutes an oil passage.

[0037] Here, first, the configuration of the case 2 will be described with reference to FIG. 2 and the like, and then the oil passage structure will be described with reference to FIG. 5 and subsequent figures.

[0038] In this embodiment, the case 2 includes an integrated motor case 21, a transmission mechanism case 22, an output shaft case 23, and an inverter case 24. Here, "integrated" includes an integrated configuration using fastening members such as bolts, and an integrated configuration using integral molding (for example, casting or pouring using aluminizing).

[0039] The motor case 21 forms a motor accommodating chamber S1 that accommodates the rotating electric machine 1, the transmission mechanism case 22 forms a transmission mechanism accommodating chamber S2 that accommodates the transmission mechanism 3, the output shaft case 23 forms an output shaft accommodating chamber S3 that accommodates the first output member 61, and the inverter case 24 forms an inverter accommodating chamber S4 that accommodates the inverter device 70. Note that, "the motor case 21 forms the motor accommodating chamber S1" means that the wall portions that bound the motor accommodating chamber S1 form the motor case 21. This also applies to the transmission mechanism case 22, the output shaft case 23, and the inverter case 24.

[0040] The motor case 21 has a cylindrical shape corresponding to the outer shape of the rotating electric machine 1. However, the motor case 21 does not need to have the entire cylindrical outer periphery closed. For example, the motor accommodating chamber S1 and the output shaft accommodating chamber S3 may be in communication with each other, in which case the side of the motor case 21 facing the output shaft accommodating chamber S3 does not need to have a wall (partition).

[0041] The transmission mechanism case 22 is provided on the axial direction A2 side with respect to the motor case 21 and the output shaft case 23. The output shaft case 23 is provided on the X2 side with respect to the motor case 21. The inverter case 24 is provided above the transmission mechanism case 22 and the output shaft case 23. Details of the inverter case 24 will be described later.

[0042] In this embodiment, since the output shaft case portion 23 is provided, the first output member 61 can be more effectively protected from the external environment (for example, flying stones) than when the first output member 61 is provided outside the case 2. In addition, the clearance that must be ensured between the first output member 61 and peripheral components can be reduced. However, in a modified example, the first output member 61 may be provided outside the case 2.

[0043] The case 2 may be formed by joining multiple members (case members and cover members). Therefore, one case member forming the case 2 may form two or more case members among the motor case 21, the transmission mechanism case 22, the output shaft case 23, and the inverter case 24.

[0044] Furthermore, the motor accommodating chamber S1, the transmission mechanism accommodating chamber S2, the output shaft accommodating chamber S3, and the inverter accommodating chamber S4 formed by the case 2 may be completely isolated from one another, may be partially in communication with one another, or may be shared without any boundary. For example, the motor accommodating chamber S1 and the output shaft accommodating chamber S3 may be shared without any partition separating them. In this case, the rotating electric machine 1 and the first output member 61 are accommodated in a common accommodation chamber (specifically, the motor accommodating chamber S1 and the output shaft accommodating chamber S3) formed by the case 2. Furthermore, if the rotating electric machine 1 is oil-cooled, the motor accommodating chamber S1 and the inverter accommodating chamber S4 may be separated from one another, but if the rotating electric machine 1 is completely water-cooled, the motor accommodating chamber S1 and the inverter accommodating chamber S4 do not need to be separated from one another.

[0045] In the following description, as an example, the case 2 is formed by joining a case member 200, a motor cover member 201, a differential cover member 202, and an inverter cover member 203. The joining method may be fastening with bolts or the like.

[0046] The case member 200 may be formed as a one-piece member (for example, a single member made of a common material formed by die casting). In this case, the motor accommodating chamber S1 and the transmission mechanism accommodating chamber S2 may be separated by a single partition wall 26.

[0047] The case member 200 is open in the axial direction on the axial direction A1 side and also on the axial direction A2 side.

[0048] The motor cover member 201 is provided so as to cover the opening of the case member 200 on the axial direction A1 side (i.e., the opening of the motor accommodating chamber S1 on the axial direction A1 side). The motor cover member 201 may be formed as a one-piece member. The motor cover member 201 may be joined to the end face (joint surface) on the axial direction A1 side of the case member 200. In this case, the joint surface (mating surface) 221 between the motor cover member 201 and the case member 200 may extend in a plane perpendicular to the axial direction.

[0049] The differential cover member 202 is provided so as to cover the opening of the case member 200 on the axial direction A2 side (i.e., the opening of the transmission mechanism accommodating chamber S2 on the axial direction A2 side). The differential cover member 202 may be formed as a one-piece member. The differential cover member 202 may be joined to the end face (joint surface) on the axial direction A2 side of the case member 200. In this case, the joint surface (mating surface) 222 between the differential cover member 202 and the case member 200 may extend in a plane perpendicular to the axial direction.

[0050] The inverter cover member 203 is provided so as to cover the opening of the inverter accommodating chamber S4 in the case member 200. The inverter cover member 203 may be formed as a one-piece member.

[0051] The inverter device 70 may be in the form of a module, and may be fixed by bolts or the like to a wall portion that forms the inverter case portion 24. The inverter device 70 includes a plurality of switching elements (power semiconductor elements, not shown) that constitute an inverter circuit, a control board (not shown) on which a control device that controls the inverter circuit is mounted, a smoothing capacitor, etc.

[0052] Fig. 5 is a cross-sectional view taken along a plane passing through the second axis C2 and the Y direction, and is an enlarged view of part Q6 in Fig. 2 (a cross-sectional view passing through the output shaft accommodation chamber S3). Fig. 6 is a side view schematically showing the vehicle drive device 100 according to this embodiment as viewed from the A2 side. Fig. 7 is a perspective view schematically showing the vehicle drive device 100 according to this embodiment as viewed from the A2 side. In Figs. 6 and 7, the differential cover member 202 is omitted so that the state inside the transmission mechanism accommodation chamber S2 can be seen.

[0053] As described above, the transmission mechanism accommodating chamber S2 and the output shaft accommodating chamber S3 overlap the second axis C2 in top view and are adjacent to each other in the axial direction. Furthermore, the transmission mechanism accommodating chamber S2 extends in the X direction to accommodate the reduction gear mechanism 34 and the differential gear mechanism 5, and therefore the transmission mechanism accommodating chamber S2 and the output shaft accommodating chamber S3 extend in an L shape in top view. Hereinafter, the portion of the transmission mechanism accommodating chamber S2 that accommodates the reduction gear mechanism 34 will also be referred to as the "reduction mechanism accommodating chamber S21," and the portion that accommodates the differential gear mechanism 5 will also be referred to as the "differential gear accommodating chamber S22."

[0054] The output shaft case portion 23 extends around the second axis C2 along the extending direction (i.e., the axial direction) of the first output member 61. The output shaft case portion 23 may be in the form of a peripheral wall portion that forms a space S33 (space including the output shaft accommodating chamber S3) around the first output member 61. In this case, the space S33 (space including the output shaft accommodating chamber S3) around the first output member 61 includes an annular space portion around the first output member 61 when viewed in the axial direction A. Note that in this case, the output shaft case portion 23 extends radially outward (toward the X2 direction) of the rotating electric machine 1 and may also form a part of the motor case portion 21.

[0055] In this embodiment, the output shaft accommodating chamber S3 communicates with the transmission mechanism accommodating chamber S2 (particularly the differential gear accommodating chamber S22) on its axial direction A2 side. An object to be lubricated with oil is disposed on the axial direction A1 side of the output shaft accommodating chamber S3. That is, the axial direction A1 side end of the output shaft accommodating chamber S3 communicates with a space S31 in which an object to be lubricated with oil is disposed. The space S31 may be formed by the motor cover member 201. In this case, the space S33 around the first output member 61 is formed by the output shaft accommodating chamber S3 and the space S31 being continuous in the axial direction. In this embodiment, the object to be lubricated with oil includes a bearing BR2 and an oil seal 700. The oil seal 700 is provided at the A1 side end of the first output member 61 and provides an oil-tight seal between the first output member 61 and the case 2. In a modified example, the output shaft accommodating chamber S3 may have an end on the axial direction A1 side that contains the space S31 (the space in which the bearing BR2 and the oil seal 700 are disposed) instead of communicating with the space S31 in which the bearing BR2 and the oil seal 700 are disposed. In this case, the space S33 around the first output member 61 is made up of the output shaft accommodating chamber S3.

[0056] In this embodiment, oil is circulated within the vehicle drive system 100 not by a so-called forced lubrication method using an oil pump (mechanical or electric oil pump), but by a lubrication method (natural lubrication method) in which oil is scooped up by the rotation of the gears to lubricate the oil. However, in a modified example, an oil pump may also be used for part of the lubrication.

[0057] Specifically, in this embodiment, a lubrication method is adopted in which various objects to be lubricated are lubricated by scraping up the oil using the rotation of the output gear 30 (so-called differential ring) of the differential gear mechanism 5.

[0058] In this way, according to this embodiment, by adopting such a natural lubrication system in the vehicle drive system 100, it is possible to reduce costs and size by eliminating the oil pump.

[0059] On the other hand, the natural lubrication method often requires raising the oil level or providing additional components such as a catch tank in order to properly supply oil to the above-mentioned bearing BR2 and oil seal 700. Furthermore, raising the oil level requires a larger amount of oil, which increases costs.

[0060] Therefore, in this embodiment, the surface 231 (hereinafter also referred to as the "inner peripheral surface 231 of the peripheral wall") (see Figure 5) facing the first output member 61 in the output shaft case portion 23 and the outer peripheral surface of the first output member 61 are configured so that the axial direction A1 side extends to a position lower than the axial direction A2 side.

[0061] Specifically, the inner peripheral surface 231 of the peripheral wall includes an inclined surface that forms a height difference between the axial direction A1 side and the axial direction A2 side. 2 Axis C 2 However, in other embodiments, a step may be formed instead of or in addition to the inclined surface. In this case, the step is also formed by increasing the inner diameter (the inner diameter of the inner peripheral surface 231 of the peripheral wall) of the inner peripheral surface 231 of the peripheral wall. 2 Axis C 2 The inner diameter around the center of the groove may be formed so as to gradually increase toward the axial direction A1.

[0062] Similarly, the outer peripheral surface of the first output member 61 also includes an inclined surface that forms a difference in height between the axial direction A1 side and the axial direction A2 side. Such an inclined surface may be realized by increasing the outer diameter (outer diameter around the first axis C1) of the outer peripheral surface of the first output member 61 toward the axial direction A1 side. In this case, the outer diameter of the outer peripheral surface of the first output member 61 may be smaller by a constant value than the inner diameter of the peripheral wall inner peripheral surface 231 at each position along the axial direction. However, in other embodiments, a step may be formed instead of or in addition to the inclined surface.

[0063] The inner peripheral surface 231 of the peripheral wall and the outer peripheral surface of the first output member 61 can utilize the action of gravity to allow oil supplied from the axial direction A2 side by rotation of the output gear 30 of the differential gear mechanism 5 to flow at a relatively high flow rate along the inclined surface toward the axial direction A1 side. Specifically, oil supplied from the axial direction A2 side by rotation of the output gear 30 of the differential gear mechanism 5 (see arrow R61 in FIG. 5 ) falls onto the surface of the first output member 61 and then flows along the surface of the first output member 61 toward the axial direction A1 side (see arrow R62 in FIG. 5 ). At this time, the inclination of the surface of the first output member 61 promotes the flow of oil toward the axial direction A1 side. Furthermore, oil supplied from the axial direction A2 side by rotation of the output gear 30 of the differential gear mechanism 5 (see arrow R61 in FIG. 5 ) falls onto the surface portion of the inner peripheral surface 231 facing upward via the surface of the first output member 61 or directly. The oil then flows toward the axial direction A1 along the upward-facing surface portion of the peripheral wall inner circumferential surface 231 (see arrow R63 in FIG. 5). At this time, the flow of oil toward the axial direction A1 is promoted due to the inclination of the peripheral wall inner circumferential surface 231. As a result, oil can be supplied at an appropriate flow rate to the A1-side end of the first output member 61 or to objects to be lubricated (such as the bearing BR2 and the oil seal 700) provided in the vicinity thereof.

[0064] In this way, according to this embodiment, oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 can be appropriately supplied to the objects to be lubricated (the bearing BR2 and the oil seal 700) without providing an additional component such as a catch tank. Therefore, while achieving size and cost reduction through the natural lubrication system, oil can also be appropriately supplied to objects to be lubricated (the bearing BR2 and the oil seal 700) that are located relatively far in the axial direction from the output gear 30 of the differential gear mechanism 5.

[0065] In order to supply oil to the objects to be lubricated (bearing BR2 and oil seal 700) at an appropriate flow rate, it is useful to introduce the oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 into the output shaft accommodating chamber S3 from the axial direction A2 side at an appropriate flow rate.

[0066] Therefore, in this embodiment, a portion of the transmission mechanism case 22 located at the boundary with the output shaft case 23 in the axial direction (hereinafter also referred to as the "bearing support portion 223") has a cavity S223. The bearing support portion 223 is located around the bearing BR1 and supports the bearing BR1. In this case, the cavity S223 may be formed radially outward of the bearing BR1 at a height that will allow oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 to fall thereon. Two or more cavities S223 may be provided around the bearing BR1, for example, directly above (at the 12 o'clock position) and at a position below (for example, at the 11 o'clock position) in the vertical direction.

[0067] By providing such a hollow portion S223, oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 can be introduced into the output shaft accommodating chamber S3 from the axial direction A2 side at an appropriate flow rate. Furthermore, the oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 can be directly introduced into the hollow portion S223. Therefore, oil can be introduced into the output shaft accommodating chamber S3 from the axial direction A2 side at an appropriate flow rate without providing an additional component such as a catch tank.

[0068] In this embodiment, oil supplied to the motor housing chamber S1 and the output shaft housing chamber S3 (see Figures 2 and 5) for lubrication, etc. is returned to the transmission mechanism housing chamber S2 (particularly the differential gear housing chamber S22) via a return flow path 290 (see Figure 3) formed in the lower part of the case 2.

[0069] The return flow passage 290 has an A2 side end that opens into the differential gear accommodating chamber S22 and an A1 side end that communicates with the output shaft accommodating chamber S3. The output shaft case portion 23 may have an opening or notch 99 (see FIG. 3) for ensuring communication between the output shaft accommodating chamber S3 and the return flow passage 290. This allows oil to be efficiently introduced from inside the output shaft accommodating chamber S3 into the return flow passage 290.

[0070] Next, with reference mainly to FIG. 6, the structure within the transmission mechanism accommodation chamber S2 of the oil passage structure will be mainly described.

[0071] As described above, this embodiment employs a natural lubrication system, which allows oil used to lubricate various objects to be returned relatively quickly to the lower portion of the differential gear housing chamber S22 (the oil reservoir in which the output gear 30 is immersed). For example, if a return flow path such as the return flow path 290 described above opens to the reduction mechanism housing chamber S21 other than the differential gear housing chamber S22 within the transmission mechanism housing chamber S2, the amount of oil returning to the lower portion of the differential gear housing chamber S22 via the return flow path is likely to be insufficient. In this case, depending on the vehicle's driving conditions, the oil temperature sensor may not be immersed in oil and may end up measuring the internal air temperature. To eliminate this problem, it is possible to increase the overall amount of oil, but this could result in problems such as increased costs due to the increased oil amount and increased churning loss due to a rise in the oil level in a static state (churning loss due to the output gear 30).

[0072] Therefore, in this embodiment, the return flow passage 290 opens at a portion of the transmission mechanism accommodating chamber S2 below the differential gear accommodating chamber S22 (below the second axis C2). In this case, the end portion of the return flow passage 290 on the axial direction A2 side (the opening on the differential gear accommodating chamber S22 side) preferably overlaps with the output gear 30 when viewed in the axial direction. This makes it possible to relatively quickly return oil used to lubricate various objects to be lubricated, including the above-mentioned bearing BR2, oil seal 700, etc., to the lower portion of the differential gear accommodating chamber S22 (the oil reservoir in which the output gear 30 is immersed).

[0073] In this embodiment, as described above, a flow path forming member 90 is provided on the radially outer side of the rotating electric machine 1. The radially inner side of the flow path forming member 90 is fitted into the stator core 12, and the radially outer side is sealed on both axial sides against the flow path forming surface 209 of the case 2. That is, the flow path forming member 90 is provided in a manner that separates a space S11 (see FIG. 2 ) in which the coil ends 13 on the axial direction A2 side of the motor accommodating chamber S1 (in this embodiment, the lead-side coil ends 13) are located, and a space S12 (see FIG. 2 ) in which the coil ends 13 on the axial direction A1 side are located. Therefore, the space S11 (see FIG. 2 ) in which the coil ends 13 on the axial direction A2 side of the motor accommodating chamber S1 (in this embodiment, the lead-side coil ends 13) are located and the space S12 (see FIG. 2 ) in which the coil ends 13 on the axial direction A1 side are located are not substantially in communication with each other in the axial direction. Therefore, the oil sprayed toward each coil end 13 through the axial oil passage 15a of the rotor shaft 15 and the radial ejection holes 15b of the rotor shaft 15 (oil sprayed by centrifugal force when the rotor rotates) cannot be returned to the transmission mechanism accommodating chamber S2 using only one return flow path. Specifically, the oil sprayed toward the coil ends 13 in the space S12 can return to the transmission mechanism accommodating chamber S2 (particularly the differential gear accommodating chamber S22) through the return flow path 290 described above due to the communication between the space S12 and the output shaft accommodating chamber S3 (see FIG. 2). On the other hand, the oil sprayed toward the coil ends 13 in the space S11 cannot substantially return to the transmission mechanism accommodating chamber S2 (particularly the differential gear accommodating chamber S22) through the return flow path 290 described above.

[0074] Therefore, in this embodiment, a return flow path 292 that communicates between the space S11 and the transmission mechanism accommodating chamber S2 is provided as a second return flow path. Specifically, the return flow path 292 has an axial A1 side end that communicates with the space S11 of the motor accommodating chamber S1, and an axial A2 side end that communicates with a lower portion of the transmission mechanism accommodating chamber S2. In this embodiment, the axial A2 side end of the return flow path 292 opens to a lower portion of the reduction mechanism accommodating chamber S21 (below the first axis C1). In this case, the axial A2 side end of the return flow path 292 (the opening on the reduction mechanism accommodating chamber S21 side) preferably opens below the second axis C2. This allows the oil used to cool the coil end 13 in the above-mentioned space S11 to be returned to a lower portion of the differential gear accommodating chamber S22 (an oil reservoir in which the output gear 30 is immersed) via the reduction mechanism accommodating chamber S21. In other words, while realizing a water-cooling structure around the stator core 12 using the flow path forming member 90, the oil supplied into the motor accommodating chamber S1 can be efficiently returned to the lower part of the differential gear accommodating chamber S22 (the oil reservoir in which the output gear 30 is immersed).

[0075] In this embodiment, the end portion of the return flow passage 292 on the axial direction A2 side (the opening on the reduction mechanism housing chamber S21 side) is disposed in a catch tank 920 in the reduction mechanism housing chamber S21.

[0076] As shown in FIG. 6 , the catch tank 920 extends radially outward from a wall portion 9201 in the axial direction around the reduction mechanism 34 in the reduction mechanism housing chamber S21 and has an inlet 921 at a position where it can capture oil scooped up by the rotation of the output gear 30. The catch tank 920 also has a discharge port 922 that opens to the differential gear housing chamber S22 at its lower portion. In this case, the end of the return flow path 292 on the axial direction A2 side (the opening on the reduction mechanism housing chamber S21 side) may be provided near the discharge port 922. This allows the oil used to cool the coil end 13 in the above-mentioned space S11 to be relatively quickly returned to the lower portion of the differential gear housing chamber S22 (the oil reservoir in which the output gear 30 is immersed) via the lower portion of the catch tank 920. The catch tank 920 may also be connected to the axial oil passage 15a of the rotor shaft 15, etc., so as to supply oil to the axial oil passage 15a of the rotor shaft 15.

[0077] In a modified example, the return flow path 292 may be connected to the above-described return flow path 290. For example, the return flow path 292 may be formed as a flow path that connects the space S11 and the return flow path 290. In this case, the overall length of the return flow path can be reduced, and an efficient return flow path configuration can be achieved.

[0078] An oil temperature sensor 98 (the placement of which is shown schematically by a circle in FIG. 6) is provided below the catch tank 920. In this case, the oil temperature sensor 98 is provided near the outlet 922 of the catch tank 920. This reduces the possibility that the oil temperature sensor 98 will be above the oil level depending on the running state of the vehicle, thereby improving the reliability of the sensor information from the oil temperature sensor 98.

[0079] In this manner, in this embodiment, as described above, the oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 is introduced from the transmission mechanism accommodating chamber S2 into the output shaft accommodating chamber S3 via the hollow portion S223 located above the second shaft C2. The oil then flows downward due to gravity, lubricating the bearing BR2 and the like, and then is returned from the output shaft accommodating chamber S3 to the differential gear accommodating chamber S22 via the end (the end on the axial direction A2 side) of the return flow passage 290 located below the second shaft C2. This allows the oil to be scooped up again by the rotation of the output gear 30 of the differential gear mechanism 5.

[0080] Furthermore, oil scooped up by the rotation of the output gear 30 of the differential gear mechanism 5 is introduced into the axial oil passage 15a of the rotor shaft 15 via the catch tank 920 and is then ejected from the ejection holes 15b onto the coil ends 13 of the rotating electric machine 1, as described above. The oil ejected onto the coil ends 13 in the space S12 of the motor housing chamber S1 is returned from the space S12 to the transmission mechanism housing chamber S2 via an end (the end on the axial direction A2 side) of the return flow passage 290 located below the second axis C2. The oil ejected onto the coil ends 13 in the space S11 of the motor housing chamber S1 is returned from the space S11 to the transmission mechanism housing chamber S2 via an end (the end on the axial direction A2 side) of the return flow passage 292 located below the second axis C2. The oil returned to the transmission mechanism housing chamber S2 in this way is returned to the differential gear housing chamber S22 via an outlet 922 in the catch tank 920 located below the second axis C2. As a result, the rotation of the output gear 30 of the differential gear mechanism 5 makes it possible to lift the oil again.

[0081] Although each embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0082] For example, in the above-described embodiment, both the surface (inner peripheral surface 231 of the peripheral wall) of the output shaft case portion 23 facing the first output member 61 and the outer peripheral surface of the first output member 61 have inclined surfaces, but this is not limitative. For example, only the inner peripheral surface 231 of the peripheral wall may have an inclined surface.

[0083] In the above-described embodiment, the output shaft case portion 23 is in the form of a peripheral wall portion that surrounds the first output member 61 in at least a partial section in the axial direction of the first output member 61, but is not limited to this. For example, the output shaft case portion 23 may face only a portion of the periphery of the first output member 61, including the lower side. [Explanation of symbols]

[0084] 100... Vehicle drive device, 1... Rotating electric machine (drive source), 2... Case, 22... Transmission mechanism case portion (gear case portion), 23... Output shaft case portion (wall portion, peripheral wall portion), 231... Inner peripheral wall surface (surface of wall portion), 290... Return flow path (communicating passage), 34... Reduction mechanism (transmission mechanism), 30... Output gear (ring gear), 5... Differential gear mechanism (transmission mechanism), 61... First output member (shaft member), 99... Opening or notch, BR1... Bearing (first bearing), BR2... Bearing (second bearing), S223... Cavity portion, S31... Space (object placement space), W... Wheel

Claims

1. a transmission mechanism that transmits driving force from a driving source to a wheel via a shaft member; a case that accommodates the transmission mechanism and at least a portion of the shaft member, The case is a gear case portion in which oil that can be scooped up by rotation of the gears of the transmission mechanism accumulates; a wall portion that bounds at least a lower side of a space around the shaft member and extends along an extension direction of the shaft member; The space around the shaft member has one side in the extension direction of the shaft member communicating with the inside of the gear case portion, and the other side containing an object arrangement space in which an object to be lubricated by oil is arranged or communicating with the object arrangement space, The oil scooped up by the rotation of the gears of the transmission mechanism is supplied to the object to be lubricated in the space around the shaft member or to the object to be lubricated via the space around the shaft member, A vehicle drive device in which the surface of the wall portion facing the lower side of the shaft member, or the outer surface of the shaft member, has a height on the other side in the extension direction of the shaft member that is lower than the height on the one side.

2. A vehicle drive device as described in claim 1, wherein the surface of the wall portion or the outer surface of the shaft member includes an inclined surface or step that forms a height difference between the other side and the one side.

3. The one side of the shaft member in the extension direction is supported by the case via a first bearing, 2. The vehicle drive device according to claim 1, wherein the case has a hollow portion radially outward of the first bearing and above the axis of the shaft member, the hollow portion connecting the space around the shaft member with the interior of the gear case portion.

4. The other side of the shaft member in the extension direction is supported by the case via a second bearing, The vehicle drive device according to claim 1 , wherein the object to be lubricated includes the second bearing.

5. The case has a communication passage for returning oil used to lubricate the object to be lubricated to the inside of the gear case portion, The vehicle drive device according to claim 1 , wherein the wall portion has a hole or a notch that connects the object placement space to the communication passage.

6. Further comprising a rotating electric machine forming the driving source, the transmission mechanism includes a reduction mechanism and a differential gear mechanism, the case accommodates the rotating electric machine, the reduction mechanism, the differential gear mechanism, and the shaft member; the gear is a ring gear of the differential gear mechanism, The vehicle drive device according to claim 1 , wherein the wall portion extends radially outward of the rotating electric machine.

7. The wall portion has the form of a peripheral wall portion that bounds the space around the shaft member over the entire circumference in at least a portion of the extension direction of the shaft member, 6. The vehicle drive device according to claim 1, wherein an inner diameter of the peripheral wall portion and an outer diameter of the shaft member increase from the one side to the other side in the extension direction of the shaft member.

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