Vehicle drive device

Abstract

This invention provides a vehicle drive unit capable of reducing the height of a variable speed drive axle. In the vehicle drive unit, (a) one side of the drive shaft has a differential-side connecting shaft, which is a shaft closer to the side connected to the differential gear drive than the inner part constituting the differential-side constant velocity universal joint and has a smaller diameter than the inner part; (b) the variable speed drive axle has a housing that houses a first rotary motor, a drive gear, a power distribution mechanism, an intermediate gear mechanism, a second rotary motor, and a differential gear; (c) the fastening surfaces of the housing body and the cover in the housing are arranged such that, in the radial direction of the second stator of the second rotary motor, they overlap with the differential-side connecting shaft but not with the inner part.

Description

Technical Field

[0001] This relates to a vehicle drive unit mounted on a vehicle. Background Technology

[0002] A known vehicle drive system comprises: (i) an engine; a transmission drive axle having a first rotary motor mounted on a first shaft, an output gear mounted on the first shaft, a power distribution mechanism that distributes and transmits the engine's output torque to the first rotary motor and the output gear and is mounted on the first shaft, an intermediate gear mechanism that includes an intermediate gear meshing with the output gear and is mounted on a second shaft, a second rotary motor that is drivenly connected to the intermediate gear mechanism and is mounted on a third shaft, and a differential gear that is drivenly connected to the intermediate gear mechanism and is mounted on a fourth shaft; and a pair of drive shafts that are drivenly connected to the differential gear; (ii) the first, second, third, and fourth shafts are parallel to each other; and (iii) of the first, second, third, and fourth shafts, the third shaft is mounted on the vehicle at the top. For example, this is described in Patent Document 1.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-23036 Summary of the Invention

[0004] In the vehicle drive unit described in Patent Document 1, it is desirable to shorten the height dimension of the transmission drive axle when mounted on a vehicle.

[0005] The present invention was made against the background described above, and its object is to provide a vehicle drive device that can reduce the height dimension of the variable speed drive axle.

[0006] The key point of the present invention is a vehicle drive unit, (i) comprising: an engine; a transmission drive axle having a first rotary motor disposed on a first shaft, an output gear disposed on the first shaft, and a power distribution mechanism disposed on the first shaft for distributing and transmitting the output torque of the engine to the first rotary motor and the output gear, an intermediate gear mechanism including an intermediate gear meshing with the output gear and disposed on a second shaft, a second rotary motor drivenly connected to the intermediate gear mechanism and disposed on a third shaft, and a differential gear drivenly connected to the intermediate gear mechanism and disposed on a fourth shaft; and a pair of drive shafts drivenly connected to the differential gear, (ii) the first shaft, the second shaft, the third shaft, and the fourth shaft are respectively parallel, (iii) the stator of the second rotary motor is disposed in an overlapping position radially relative to one side of the pair of drive shafts, (iv) Of the first, second, third, and fourth shafts, the third shaft is mounted on the vehicle at the top. In the vehicle drive unit, (a) the drive shaft on one side has a small diameter portion, which is a shaft that is closer to the side connected to the differential gear drive than the inner portion that constitutes the constant velocity universal joint and has a smaller diameter than the inner portion; (b) the transmission drive axle also has a housing that houses the first rotary motor, the output gear, the power distribution mechanism, the intermediate gear mechanism, the second rotary motor, and the differential gear; (c) the housing has a housing body and a cover, the housing body having an opening that opens toward the drive shaft on one side in the direction of the fourth shaft, and the cover closing the opening; (d) the fastening surfaces of the housing body and the cover are configured to overlap with the small diameter portion but not with the inner portion in the radial direction of the stator of the second rotary motor relative to the drive shaft on one side.

[0007] Invention Effects

[0008] According to the vehicle drive device of the present invention, (a) the drive shaft on one side has a small-diameter portion, which is closer to the side of the shaft connected to the differential gear than the inner portion constituting the constant velocity universal joint and has a smaller diameter than the inner portion; (b) the transmission drive axle also has a housing that houses the first rotary motor, the output gear, the power distribution mechanism, the intermediate gear mechanism, the second rotary motor, and the differential gear; (c) the housing has a housing body and a cover, the housing body having an opening in the direction of the fourth shaft toward the drive shaft on one side, and the cover closing the opening; (d) the fastening surfaces of the housing body and the cover are configured to overlap with the small-diameter portion but not with the inner portion in the radial direction of the stator of the second rotary motor relative to the drive shaft on one side. Therefore, compared to the case where the fastening surface overlaps with the inner portion, it is necessary to shorten the distance between the stator of the second rotary motor and the fourth shaft, thereby allowing the position of the third shaft to be closer to the fourth shaft. That is, by bringing the third shaft, which is equipped with the second rotary motor, closer to the fourth shaft, which is located further down than the third shaft, the height of the transmission drive axle can be shortened. Attached Figure Description

[0009] Figure 1 This is a block diagram illustrating the general structure of a vehicle equipped with the vehicle drive device according to Embodiment 1.

[0010] Figure 2 It is an explanation of the composition Figure 1 A schematic diagram of the configuration of the components of the variable speed drive axle in a vehicle-width direction view.

[0011] Figure 3 It is along Figure 2 The cutting lines XX and YY shown cut a partial cross-sectional view of the transmission drive axle.

[0012] Figure 4 This is a partial cross-sectional view of the transmission drive axle of the vehicle drive unit involved in the comparative example.

[0013] Figure 5 This is a partial cross-sectional view of the transmission drive axle of the vehicle drive unit involved in Embodiment 2. Detailed Implementation

[0014] Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in each embodiment, the drawings are appropriately simplified or modified, and the dimensional proportions and shapes of the parts are not necessarily depicted accurately.

[0015] [Example 1]

[0016] Figure 1This is a block diagram illustrating the general structure of a vehicle 10 equipped with the vehicle drive device 98 according to Embodiment 1.

[0017] Vehicle 10 is a hybrid vehicle equipped with an engine 12, a first rotary motor MG1, and a second rotary motor MG2, which function as power sources. Engine 12 is a known internal combustion engine. The first rotary motor MG1 and the second rotary motor MG2 are, for example, rotating electrical machines with both electric motor and generator functions, and are so-called electric motor generators. The first rotary motor MG1 and the second rotary motor MG2 are of the internal rotor type. Vehicle 10 has a power transmission device 16 along the power transmission path between these power sources and a pair of drive wheels 14.

[0018] The power transmission device 16, along the power transmission path between the engine 12 and a pair of drive wheels 14, sequentially includes a crankshaft 12a, a damper 20, an input shaft 22, a power distribution mechanism 24, a drive gear 26a, a driven gear 32, an intermediate shaft 34, a final gear 36, and a differential gear 38 from the engine 12 side. These are all known structures. The drive gear 26a corresponds to the "output gear" in this invention. The driven gear 32 corresponds to the "intermediate gear" in this invention. The driven gear 32 meshes with the drive gear 26a. The intermediate shaft 34, including the driven gear 32 and disposed on the second shaft C2, and the final gear 36 constitute the intermediate gear mechanism 30. The final gear 36 meshes with the differential ring gear 38r of the differential gear 38. Thus, the differential gear 38 is drivenly connected to the intermediate gear mechanism 30. The power distribution mechanism 24, the drive gear 26a, the intermediate gear mechanism 30, and the differential gear 38 are housed within the housing 70. The housing 70 is a housing composed of non-rotating components with an oil-tight, sealed structure. In the power transmission path between the second rotary motor MG2 and the driven gear 32, the power transmission device 16, within the housing 70, sequentially includes a second rotor shaft MG2r and a reduction gear 40 from the side of the second rotary motor MG2; these are known structures. The second rotor shaft MG2r is the output shaft of the second rotary motor MG2. The reduction gear 40 meshes with the driven gear 32. Thus, the second rotary motor MG2 is driven and connected to the intermediate gear mechanism 30, which is located in the power transmission path between the power distribution mechanism 24 and a pair of drive wheels 14.

[0019] The power transmission device 16 has a pair of drive shafts 42 between the differential gear 38 and a pair of drive wheels 14. The pair of drive shafts 42 are drivenly connected to the differential gear 38. The engine 12, damper 20, input shaft 22, power distribution mechanism 24, and drive gear 26a are arranged on the first shaft C1, which is their rotation center line. The intermediate gear mechanism 30, which consists of driven gear 32, intermediate shaft 34, and final gear 36, is arranged on its rotation center line, i.e., the second shaft C2. The second rotary motor MG2 and reduction gear 40 are arranged on the third shaft C3, which is their rotation center line. The differential gear 38 is arranged on the fourth shaft C4, which is its rotation center line. In the power transmission device 16, the first rotary motor MG1, drive gear 26a, power distribution mechanism 24, intermediate gear mechanism 30, second rotary motor MG2, differential gear 38, and housing 70 constitute a transmission drive axle 96. The vehicle drive unit 98 includes an engine 12, a transmission drive axle 96, and a pair of drive shafts 42.

[0020] When mounted on vehicle 10, the transmission drive axle 96 is configured such that axle 1 C1, axle 2 C2, axle 3 C3, and axle 4 C4 are in the vehicle width direction. The "vehicle width direction" refers to the width direction of vehicle 10, which is perpendicular to and horizontal to the front-rear direction. Thus, axle 1 C1, axle 2 C2, axle 3 C3, and axle 4 C4 are parallel.

[0021] The power distribution mechanism 24 is, for example, a known single-gear planetary gear unit, comprising a sun gear S, a planet carrier CA, and a ring gear R. The sun gear S is connected to the first rotor shaft MG1r. The first rotor shaft MG1r is the output shaft of the first rotary motor MG1. The planet carrier CA is connected to the engine 12 via the input shaft 22, etc. The ring gear R is formed on a portion of the inner circumferential surface of the compound gear 26 and is integrally connected to the drive gear 26a. The compound gear 26 is the rotating body on the output side of the power distribution mechanism 24, and the drive gear 26a is formed on a portion of its outer circumferential surface. The power distribution mechanism 24 distributes and transmits the engine torque Te [N·m], which is the output torque of the engine 12, to the first rotary motor MG1 and the drive gear 26a. Furthermore, in this specification, unless otherwise specified, torque, driving force, power, and force (= power) are the same. The power distribution mechanism 24 is a known electric transmission mechanism that controls the differential state of the planetary gear unit by controlling the operating state of the first rotary motor MG1. Additionally, the first rotary motor MG1 can also function as a power source that outputs power to a pair of drive wheels 14 via the power distribution mechanism 24. The power transmission device 16 is preferably used, for example, in FF (front-engine, front-wheel drive) vehicles.

[0022] The housing 70 is made of, for example, an aluminum alloy casting. The housing 70 includes, for example, a housing body 72 and a cover 78. The housing body 72 is, for example, composed of a first housing portion 74 and a second housing portion 76. The first housing portion 74 is a bottomed cylindrical component. The second housing portion 76 is a cylindrical component. The first housing portion 74 and the second housing portion 76 are integrally connected by fasteners such as bolts 82, so that the opening on the side of the first housing portion 74 opposite to the engine 12 side is aligned with the opening on the engine 12 side of the second housing portion 76. The second housing portion 76 has an opening in its sidewall opposite to the engine 12 side. That is, the housing body 72, where the first housing portion 74 and the second housing portion 76 are integrally connected, has an opening that opens toward the drive shaft 42a side in the direction of the fourth shaft C4. The cover 78 is a component that engages with the second housing portion 76 in a manner that closes the opening in the sidewall of the second housing portion 76. Before the cover 78 is joined to the second housing portion 76, i.e., before the opening in the side wall of the second housing portion 76 is closed, the first rotary motor MG1 and the second rotary motor MG2 are bolted to a predetermined seat surface (e.g., a predetermined seat surface of the partition wall within the second housing portion 76) provided in the second housing portion 76. The second housing portion 76 and the cover 78 are integrally connected by fasteners such as bolts 86. Thus, the transmission drive axle 96 is housed within the housing 70. In the cover 78, a flange 78f is provided in the portion that closes the opening of the second housing portion 76. In the second housing portion 76, a flange 76f is provided in the portion closed by the cover 78. The fastening surface Sf of the housing body 72 and the cover 78 is the surface opposite to the respective flanges 76f and 78f of the second housing portion 76 and the cover 78. In this embodiment, the fastening surface Sf is perpendicular to the third shaft C3. In addition, before the cover 78 is connected to the second housing part 76, the first rotary motor MG1 and the second rotary motor MG2 protrude outward from the opening of the housing body 72.

[0023] In the vehicle width direction, one drive shaft 42a (hereinafter referred to as "drive shaft 42a") is located on the side opposite to the engine 12, and the other drive shaft 42b (hereinafter referred to as "drive shaft 42b") is located on the side of the engine 12. That is, in the vehicle width direction, drive shaft 42a is located on the cover 78 side, and drive shaft 42b is located on the housing body 72 side. Drive shaft 42a has a differential-side constant velocity joint 44a and a wheel-side constant velocity joint 46a. Drive shaft 42b has a differential-side constant velocity joint 44b and a wheel-side constant velocity joint 46b. The differential-side constant velocity joints 44a and 44b are constant velocity joints located on the differential gear 38 side, respectively, in the two constant velocity joints of the pair of drive shafts 42. Wheel-side constant velocity joints 46a and 46b are disposed on the side of a pair of drive wheels 14, which are respectively disposed on the two constant velocity joints of a pair of drive shafts 42. Differential-side constant velocity joint 44a is equivalent to a "constant velocity joint" in this invention. Differential-side constant velocity joints 44a and 44b constitute a pair of differential-side constant velocity joints 44, and wheel-side constant velocity joints 46a and 46b constitute a pair of wheel-side constant velocity joints 46. A pair of drive shafts 42 is equivalent to a "pair of drive shafts" in this invention.

[0024] Figure 2 It is an explanation of the composition Figure 1 A schematic diagram of the configuration of the components of the transmission drive axle 96 in a vehicle-width direction view. Figure 2 In the diagram, arrows indicate the forward and backward directions of vehicle 10, as well as the upper and lower directions along the vertical line. Furthermore, the direction closer to the paper and inward, i.e., the closer side in the vehicle width direction, represents the left side of vehicle 10, and the inward side represents the right side. Figure 2 In this diagram, the first rotary motor MG1, the stator of the first rotary motor MG1 (i.e., the first stator MG1s), the drive gear 26a, the driven gear 32, the final gear 36, the second rotary motor MG2, the stator of the second rotary motor MG2 (i.e., the second stator MG2s), the reduction gear 40, the differential side connecting shaft 62 (described later), the inner part 50 (described later), the clamp 58 (described later), and the differential ring gear 38r are simplified and represented by circles. Figure 2 In the diagram, the shell 70 is represented by a dashed line, and the others are represented by solid lines.

[0025] Of the four axes C1, C2, C3, and C4, axis C3 is located at the top. From top to bottom in the vertical direction, axes C3, C2, C1, and C4 are arranged in sequence. From front to back in the front direction, axes C1, C2, and C4 are arranged in sequence.

[0026] Figure 3 It is along Figure 2 The cutting lines XX and YY shown cut a partial sectional view of the transmission drive axle 96.

[0027] Drive shaft 42a includes differential-side connecting shaft 62, differential-side constant velocity joint 44a, shaft body 60, and wheel-side constant velocity joint 46a (see reference). Figure 1 The differential-side connecting shaft 62 is driven to the side gear of the differential gear 38. The differential-side connecting shaft 62 is rotatable about the fourth shaft C4. The differential-side constant velocity joint 44a is a known structure, for example a tripod-type sliding constant velocity joint with telescoping function in the length direction of the drive shaft 42a. The differential-side constant velocity joint 44a drives the shaft body 60 to the differential-side connecting shaft 62. The shaft body 60 is driven to one side of a pair of drive wheels 14 via a wheel-side constant velocity joint 46a.

[0028] The differential-side constant velocity joint 44a is a known tripod-type sliding constant velocity joint comprising a housing 52, a tripod joint 54, and a sleeve 56. The tripod joint 54 is a known structure fixed to one end of the housing 52 side of the shaft body 60 and having three trunnions protruding outwards at equal angular intervals. The sleeve 56 is a cylindrical component, one side of which is fixed to the outer periphery of the housing 52 by closing the opening of the housing 52 with a clamp 58, and the other side is fixed to the outer periphery of the shaft body 60. The housing 52, the sleeve 56 fixed to the outer periphery of the housing 52, and the clamp 58 fixing the sleeve 56 constitute the inner portion 50. "Inner portion 50" refers to the portion in the differential-side constant velocity joint 44a that slidably accommodates one end of the shaft body 60. The inner portion 50 corresponds to the "inner portion" in this invention. The outer diameter D1 of the inner portion 50 is greater than the outer diameter D2 [m] of the differential-side connecting shaft 62. That is, the differential-side connecting shaft 62 is a shaft that is closer to the side that drives the differential gear 38 than the inner portion 50 constituting the differential-side constant velocity universal joint 44a, and its diameter is smaller than that of the inner portion 50. Furthermore, "outer diameter" refers to the diameter of these inner portions 50 and the differential-side connecting shaft 62 in their rotated state, and is twice the radius of the fourth shaft C4, which is furthest from the rotation center line. The differential-side connecting shaft 62 corresponds to the "small diameter portion" in this invention.

[0029] The second stator MG2s is configured such that, relative to the drive shaft 42a, radially, it overlaps with the differential-side connecting shaft 62 but not with the inner portion 50. That is, in the vehicle width direction, the second stator MG2s overlaps with the differential-side connecting shaft 62 but not with the inner portion 50. In the vehicle width direction view, i.e., when viewed in the vehicle width direction, the second stator MG2s overlaps with the inner portion 50 but not with the differential-side connecting shaft 62 (see reference). Figure 2 ).

[0030] like Figure 1 and Figure 3 As shown, in the vehicle width direction, the drive gear 26a, driven gear 32, and reduction gear 40 are located in the same position. Furthermore, in the vehicle width direction, the final gear 36 and differential ring gear 38r are located in the same position. In the vehicle width direction, both the first rotary motor MG1 and the second rotary motor MG2 are positioned on the side opposite to the engine 12 when viewed from the intermediate gear mechanism 30.

[0031] As described above, the fastening surface Sf is the surface facing the flanges 76f and 78f of the second housing portion 76 and the cover 78, respectively. In the flanges 76f and 78f of the second housing portion 76 and the cover 78, a plurality of fastening portions 84 are provided at predetermined intervals in their circumferential direction. A hole extending along the direction of the third axis C3 is provided in each fastening portion 84. The second housing portion 76 and the cover 78 are integrally connected by fasteners such as bolts 86 inserted into the holes provided in the fastening portions 84. That is, with the housing body 72 and the cover 78 aligned at the fastening surface Sf, the housing body 72 and the cover 78 are fastened along the direction of the third axis C3. The fastening surface Sf is configured such that, relative to the drive shaft 42a, in the radial direction of the second stator MG2s, it overlaps with the differential-side connecting shaft 62 but not with the inner portion 50. That is, in the vehicle width direction, the fastening surface Sf overlaps with the differential-side connecting shaft 62, but not with the inner side 50. In the vehicle width direction view, i.e., when viewed in the vehicle width direction, the fastening surface Sf overlaps with the inner side 50, but not with the differential-side connecting shaft 62 (see reference). Figure 2 ).

[0032] Furthermore, the second stator MG2s is configured such that, relative to the drive shaft 42a, in the radial direction of the second stator MG2s, it overlaps with the differential-side connecting shaft 62 but not with the inner portion 50. That is, in the vehicle width direction, the second stator MG2s overlaps with the differential-side connecting shaft 62, but not with the inner portion 50. In the vehicle width direction view, i.e., viewed in the vehicle width direction, the second stator MG2s overlaps with the inner portion 50, but not with the differential-side connecting shaft 62. (Reference) Figure 2 ).

[0033] Thus, a fastening surface Sf is provided between the second stator MG2s and the differential-side connecting shaft 62. When the drive shaft 42a rotates, the clearance required for the drive shaft 42a and the housing 70 to not interfere is called the "moving clearance Ld". The length of the portion of the cover 78 covering the outer periphery of the second stator MG2s, especially the portion between the second stator MG2s and the differential-side connecting shaft 62, within the cover 78 is called the "wall thickness Ln". The radially extending length of the flange 78f of the cover 78, especially the radially extending length of the flange 78f of the cover 78 in the portion between the second stator MG2s and the differential-side connecting shaft 62, is called the "flange length Lf". "Radial in flange 78f" refers to the direction in which the cover 78 extends from the inner side to the outer side of the housing 70. For example, regarding the portion of the cover 78 where a flange 78f is provided, the distance between the second stator MG2s and the differential-side connecting shaft 62 needs to be greater than or equal to the sum of the wall thickness Ln, flange length Lf, and clearance Ld (=Ln+Lf+Ld). Similarly, regarding the portion of the cover 78 where a flange 78f is not provided, the distance between the second stator MG2s and the differential-side connecting shaft 62 needs to be greater than or equal to the sum of the wall thickness Ln and clearance Ld (=Ln+Ld). That is, the second stator MG2s and the fourth shaft C4 need to be separated by a distance equal to the sum of the radius r2 (=D2 / 2), wall thickness Ln, flange length Lf, and clearance Ld of the differential-side connecting shaft 62 (=r2+Ln+Lf+Ld).

[0034] Figure 4 This is a partial cross-sectional view of the transmission drive axle 196 of the vehicle drive unit 198 involved in the comparative example. Figure 4 Compared with the above-described embodiment 1 Figure 3 Correspondingly, the structure of the transmission drive axle 196 is largely the same as that of the transmission drive axle 96 described in Embodiment 1 above, but the position of the fastening surface Sf in the vehicle width direction is mainly different. Therefore, in this comparative example, the description focuses on the parts that are different from those in Embodiment 1, and the parts that are substantially the same as those in Embodiment 1 in function are marked with the same symbols and the description is omitted as appropriate.

[0035] exist Figure 4 In this context, the fastening surface Sf represents the portion of the flanges 76f and 78f that are not fastening parts 84. In the transmission drive axle 196, the second stator MG2s is configured such that, relative to the drive shaft 42a, it radially overlaps with the differential-side connecting shaft 62 and also with the inner portion 50. Furthermore, the fastening surface Sf is configured such that, relative to the drive shaft 42a, the second stator MG2s radially overlaps with the inner portion 50.

[0036] Thus, a fastening surface Sf is provided between the second stator MG2s and the inner part 50. Therefore, the distance between the second stator MG2s and the inner part 50 needs to be greater than or equal to the sum of the wall thickness Ln, the flange length Lf, and the clearance Ld (=Ln+Lf+Ld). That is, the second stator MG2s and the fourth shaft C4 need to be separated by the sum of the radius r1 (=D1 / 2), wall thickness Ln, flange length Lf, and clearance Ld of the inner part 50 (=r1+Ln+Lf+Ld>A).

[0037] According to this embodiment, (a) the drive shaft 42a has a differential-side connecting shaft 62, which is a shaft that is closer to the side that is driven and connected to the differential gear 38 than the inner portion 50 that constitutes the differential-side constant velocity universal joint 44a, and has a smaller diameter than the inner portion 50; (b) the transmission drive axle 96 also has a housing 70, which houses the first rotary motor MG1, the drive gear 26a, the power distribution mechanism 24, the intermediate gear mechanism 30, and the first... 2. Rotary motor MG2 and differential gear 38, (c) Housing 70 has a housing body 72 and a cover 78, the housing body 72 having an opening towards the drive shaft 42a in the direction of the fourth shaft C4, and the cover 78 closing the opening, (d) The fastening surface Sf of the housing body 72 and the cover 78 is configured such that, relative to the drive shaft 42a, in the radial direction of the second stator MG2s, it overlaps with the differential-side connecting shaft 62 but not with the inner side 50. Therefore, compared to the case where the fastening surface Sf is configured to overlap with the inner side 50, the distance between the second stator MG2s and the fourth shaft C4 needs to be shortened, allowing the position of the third shaft C3 to be closer to the fourth shaft C4. That is, by bringing the third shaft C3, on which the second rotary motor MG2 is located, closer to the fourth shaft C4, which is located further below the third shaft C3, the height dimension of the transmission drive axle 96 can be shortened.

[0038] According to this embodiment, in the directional view along the fourth axis C4, a fastening part 84 is provided at the position overlapping with the inner side 50, where the housing body 72 and the cover 78 are fastened together when aligned at the fastening surface Sf. When the fastening part 84 is provided at the position overlapping with the inner side 50, the distance between adjacent fastening parts 84 of the housing body 72 and the cover 78 at the position overlapping with the inner side 50 can be reduced compared to this situation, thus improving the rigidity of the housing 70.

[0039] According to this embodiment, (a) the fastening surface Sf is perpendicular to the third axis C3 (i.e., also perpendicular to the fourth axis C4), and (b) with the housing body 72 and the cover 78 aligned at the fastening surface Sf, the housing body 72 and the cover 78 are fastened in the direction of the third axis C3 (=the direction of the fourth axis C4). When the fastener is inserted into the hole provided in the fastening part 84 and the housing body 72 and the cover 78 are integrally connected, in order to ensure the strength in the fastening part 84, the flange length Lf of the fastening part 84 with the hole needs to be a predetermined length. With the structure described above (a) and (b), compared to this case, the flange length Lf of the fastening part 84 with the hole can be shortened radially in the direction of the flange 78f. That is, in the direction perpendicular to both the third axis C3 and the fourth axis C4, the required flange length Lf of the fastening part 84 with the hole can be shortened. As a result, the flange length Lf in the fastener 84 is shortened, making it easier for the position of the third shaft C3 to move closer to the fourth shaft C4, thereby making it easier to shorten the height of the transmission drive axle 96.

[0040] [Example 2]

[0041] Figure 5 This is a partial cross-sectional view of the transmission drive axle 296 of the vehicle drive unit 298 involved in Embodiment 2. Figure 5 Compared with the above-described embodiment 1 Figure 3 Correspondingly, the structure of the transmission drive axle 296 is largely the same as that of the transmission drive axle 96 described in Embodiment 1, but the position of the fastening surface Sf is mainly different. Therefore, in this embodiment, the description focuses on the parts that are different from those in Embodiment 1, and the parts that are functionally identical to those in Embodiment 1 are marked with the same symbols and the description is appropriately omitted.

[0042] In this embodiment, the second stator MG2s is configured to overlap with the differential-side connecting shaft 62 and the inner portion 50 in the radial direction relative to the drive shaft 42a. That is, in the vehicle width direction, the second stator MG2s overlaps with the differential-side connecting shaft 62 and the inner portion 50.

[0043] In this embodiment, compared to the aforementioned Embodiment 1, the fastening surface Sf is positioned away from the differential gear 38. Similarly to Embodiment 1, the fastening surface Sf is configured to overlap with the differential-side connecting shaft 62 in the radial direction of the second stator MG2s relative to the drive shaft 42a, but not with the inner side 50.

[0044] According to this embodiment, by having the same structure as in the aforementioned embodiment 1, the same effect as in embodiment 1 is achieved by using this structure.

[0045] Furthermore, the above are various embodiments of the present invention. The present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from its spirit.

[0046] In the aforementioned embodiments 1 and 2, the fastening part 84 is provided at the position overlapping with the inner part 50 in the directional view of the fourth axis C4, but the present invention is not limited to this method. The present invention can also be applied to a method in which the fastening part 84 is not provided at the position overlapping with the inner part 50 in the directional view of the fourth axis C4.

[0047] In the aforementioned embodiments 1 and 2, (a) the fastening surface Sf is perpendicular to the third axis C3, and (b) with the housing body 72 and the cover 78 aligned at the fastening surface Sf, the housing body 72 and the cover 78 are fastened together by fasteners along the direction of the third axis C3. However, the present invention is not limited to this method. For example, the present invention can also be applied to the following methods: the fastening surface Sf is not perpendicular to the third axis C3, or the housing body 72 and the cover 78 are fastened together by fasteners in a direction other than the third axis C3.

[0048] In the aforementioned embodiments 1 and 2, the differential-side constant velocity joint 44a is a tripod-type sliding constant velocity joint, but the present invention is not limited to this. For example, the differential-side constant velocity joint 44a can also be a constant velocity joint with four or five trunnions protruding outward at equal angular intervals instead of three trunnions protruding outward at equal angular intervals. For example, the differential-side constant velocity joint 44a can be a Burfield-type fixed constant velocity joint. In the case of the Burfield-type fixed constant velocity joint, its outer ring is driven and connected to the side gear of the differential gear 38 via the differential-side connecting shaft. The outer ring, the sleeve fixed to the outer periphery of the outer ring, and the clamp fixing the sleeve constitute the inner part, which corresponds to the "inner part" in the present invention.

[0049] Symbol Explanation

[0050] 10-Vehicle, 12-Engine, 24-Power distribution mechanism, 26a-Drive gear (output gear), 30-Intermediate gear mechanism, 32-Driven gear (intermediate gear), 38-Differential gear, 42-Pair of drive shafts, 42a-Drive shaft on one side, 44a-Differential side constant velocity joint (constant velocity joint), 50-Inner side, 62-Differential side connecting shaft (small diameter part), 70-Housing, 72-Housing body, 78-Cover, 84-Fastening part, 96-Transmission drive axle, 98-Vehicle drive unit, C1-First shaft, C2-Second shaft, C3-Third shaft, C4-Fourth shaft, MG1-First rotary motor, MG2-Second rotary motor, MG2s-Second stator (stator of the second rotary motor), Sf-Fastening surface, Te-Engine torque (engine output torque).

Claims

1. A drive unit for a vehicle, comprising: engine; A variable speed drive axle includes a first rotary motor mounted on a first shaft, an output gear mounted on the first shaft, a power distribution mechanism mounted on the first shaft that distributes and transmits the output torque of the engine to the first rotary motor and the output gear, an intermediate gear mechanism mounted on a second shaft that includes an intermediate gear meshing with the output gear, a second rotary motor drivenly connected to the intermediate gear mechanism and mounted on a third shaft, and a differential gear drivenly connected to the intermediate gear mechanism and mounted on a fourth shaft; and A pair of drive shafts, which are connected to the differential gear drive. The first axis, the second axis, the third axis, and the fourth axis are all parallel. The stator of the second rotary motor is positioned in an overlapping position radially relative to one side of the pair of drive shafts. Of the first, second, third, and fourth axles, the third axle is mounted on the vehicle at the top, and the vehicle drive unit is characterized in that... One of the pair of drive shafts has a small-diameter portion, which is a shaft that is closer to the side connected to the differential gear drive than the inner portion that forms the constant velocity universal joint, and has a smaller diameter than the inner portion. The variable speed drive axle also has a housing that accommodates the first rotary motor, the output gear, the power distribution mechanism, the intermediate gear mechanism, the second rotary motor, and the differential gear. The housing has a housing body and a cover. The housing body has an opening in the direction of the fourth axis toward the drive shaft side on one side, and the cover closes the opening. The fastening surfaces of the housing body and the cover are configured such that, relative to the drive shaft on one side, in the radial direction of the stator of the second rotary motor, they overlap with the small diameter portion but not with the inner side portion.

2. The vehicle drive device according to claim 1, characterized in that, In the directional view of the fourth axis, at a position overlapping with the inner side, a fastening part is provided in which the housing body and the cover are fastened when they are aligned at the fastening surface.

3. The vehicle drive unit according to claim 2, characterized in that, The fastening surface is perpendicular to the third axis. With the housing body and the cover aligned at the fastening surface, the housing body and the cover are fastened together by fasteners along the direction of the third axis.

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