Vehicle drive systems

Abstract

To provide a vehicle drive system that facilitates weight reduction and strength maintenance of the axle case. [Solution] In the vehicle drive unit 100, the axle case 4 comprises a drive unit housing chamber 4A that houses a drive unit 10 including a rotating electric machine 2 and a differential gear mechanism 3, a first axle housing chamber 4B that houses at least a part of the first axle 11, a second axle housing chamber 4C that houses at least a part of the second axle 12, a first part 41 and a second part 42 that are arranged adjacent to each other in the axial direction L and form the drive unit housing chamber 4A, a third part 43 that is arranged adjacent to the first part 41 in the axial direction L and forms the first axle housing chamber 4B, and a fourth part 44 that is arranged adjacent to the second part 42 in the axial direction L and forms the second axle housing chamber 4C, and at least one of the first part 41 and the third part 43 and the second part 42 and the fourth part 44 is integrally formed of an aluminum alloy.

Description

Technical Field

[0001] The present invention relates to a vehicle drive device including a first axle and a second axle arranged side by side along the axial direction and each connected to a wheel, a rotating electric machine as a driving power source thereof, a differential gear mechanism that distributes the rotation transmitted from the rotating electric machine to the first axle and the second axle, and an axle case.

Background Art

[0002] An example of such a vehicle drive device is disclosed in Patent Document 1 below. In the following description of the background art, the reference numerals in Patent Document 1 are cited within parentheses.

[0003] In the vehicle drive device of Patent Document 1, the axle case (110) includes a first axle housing portion (102) that houses the first axle (124), a second axle housing portion (104) that houses the second axle (126), and a gear housing portion (140) that houses a plurality of gears constituting a differential gear mechanism (134) and the like (see FIG. 5 of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the vehicle drive device of Patent Document 1, the first axle housing portion (102) and the second axle housing portion (104) are joined to the gear housing portion (140) by bolt fastening (see FIG. 6 of Patent Document 1). Therefore, it has been difficult to sufficiently ensure the strength of each of the joint portions between the first axle housing portion (102) and the gear housing portion (140) and between the second axle housing portion (104) and the gear housing portion (140). In addition, it has caused an increase in the weight of the axle case.

[0006] Therefore, there is a need for a vehicle drive system that makes it easier to reduce the weight of the axle case while ensuring its strength. [Means for solving the problem]

[0007] In light of the above, the characteristic configuration of the vehicle drive system is: The first and second axles are arranged side by side along the axial direction, and each is connected to a wheel. A rotating electric machine which is the driving force source for the first axle and the second axle, A differential gear mechanism that distributes the rotation transmitted from the rotating electric machine to the first axle and the second axle, Equipped with an axle case, The aforementioned axle case is A drive unit housing chamber housing the drive unit including the rotating electric machine and the differential gear mechanism, A first axle housing chamber that houses at least a portion of the first axle, A second axle housing chamber that houses at least a portion of the second axle, The first and second parts are arranged adjacent to each other in the axial direction and form the drive unit housing chamber, A third portion is positioned adjacent to the first portion in the axial direction and forms the first axle housing chamber, It comprises a fourth portion which is positioned adjacent to the second portion in the axial direction and forms the second axle housing chamber, The key feature is that at least one of the first and third parts and the second and fourth parts is integrally formed from an aluminum alloy.

[0008] According to this characteristic configuration, at least one of the first and third parts of the axle case, and the second and fourth parts of the axle case, is integrally formed from an aluminum alloy. This makes it easier to reduce the weight of the axle case compared to, for example, a case where the axle case is made of an alloy mainly composed of iron. Furthermore, it reduces the number of joints in the axle case compared to a configuration where the first and third parts are separate, and the second and fourth parts are separate. Therefore, in addition to reducing the weight of the axle case, it is also easier to ensure the strength of the axle case. [Brief explanation of the drawing]

[0009] [Figure 1] Plan view of a vehicle drive system according to the first embodiment [Figure 2] Bottom view of a vehicle drive system according to the first embodiment [Figure 3] Perspective view showing the structure of the first cooling fin. [Figure 4] Sectional view IV-IV in Figure 1 [Figure 5] Plan view of a vehicle drive system according to the second embodiment [Figure 6] Plan view of a vehicle drive system according to the third embodiment [Modes for carrying out the invention]

[0010] 1. First Embodiment In the following description, the vehicle drive system 100 according to the first embodiment will be explained with reference to Figures 1 to 4.

[0011] As shown in Figures 1 and 2, the vehicle drive unit 100 comprises a first axle 11, a second axle 12, a rotating electric motor 2, a differential gear mechanism 3, and an axle case 4.

[0012] The first axle 11 and the second axle 12 are arranged coaxially. In the following description, the direction along the axis X, which is the rotational axis of the first axle 11 and the second axle 12, is defined as the "axial direction L". One side of the axial direction L is defined as the "first axial side L1", and the other side of the axial direction L is defined as the "second axial side L2". Also, the direction along the circle centered on the axis X is defined as the "circumferential direction C".

[0013] The first axle 11 and the second axle 12 are arranged side by side along the axial direction L. Each of the first axle 11 and the second axle 12 is connected to a wheel W of a vehicle on which the vehicle drive device 100 is mounted. In the present embodiment, the first axle 11 is arranged on the first axial side L1 with respect to the differential gear mechanism 3, and the second axle 12 is arranged on the second axial side L2 with respect to the differential gear mechanism 3.

[0014] The rotating electric machine 2 functions as a driving power source for the first axle 11 and the second axle 12. In the present embodiment, the rotating electric machine 2 has a function as a motor (electric motor) that receives power supply and generates power, and a function as a generator (electric generator) that receives power supply and generates electric power.

[0015] The differential gear mechanism 3 is configured to distribute the rotation transmitted from the rotating electric machine 2 to the first axle 11 and the second axle 12. In the present embodiment, the differential gear mechanism 3 is arranged on the second axial side L2 with respect to the rotating electric machine 2. In the present embodiment, a speed reducer (not shown) that decelerates the rotation of the rotating electric machine 2 and transmits it to the differential gear mechanism 3 is provided in the power transmission path between the rotating electric machine 2 and the differential gear mechanism 3.

[0016] The axle case 4 is a case used for an axle suspension device. The axle case 4 includes a drive unit housing chamber 4A, a first axle housing chamber 4B, a second axle housing chamber 4C, a first portion 41, a second portion 42, a third portion 43, and a fourth portion 44.

[0017] The drive unit housing chamber 4A is a space for housing a drive unit 10 including a rotating electric machine 2 and a differential gear mechanism 3. The first axle housing chamber 4B is a space for housing at least a part of the first axle 11. The second axle housing chamber 4C is a space for housing at least a part of the second axle 12. In the present embodiment, the first axle housing chamber 4B is disposed adjacent to the drive unit housing chamber 4A on the first axial side L1. And the second axle housing chamber 4C is disposed adjacent to the drive unit housing chamber 4A on the second axial side L2.

[0018] The first part 41 and the second part 42 are configured to form the drive unit housing chamber 4A. The first part 41 and the second part 42 are disposed adjacent to each other in the axial direction L. The first part 41 and the second part 42 are joined to each other by bolt fastening or the like. In the present embodiment, the first part 41 extends along the circumferential direction C so as to surround the rotating electric machine 2. And the second part 42 extends along the circumferential direction C so as to surround the differential gear mechanism 3. That is, in the present embodiment, the first part 41 is disposed adjacent to the second part 42 on the first axial side L1.

[0019] The third part 43 is configured to form the first axle housing chamber 4B. The third part 43 extends along the circumferential direction C so as to surround the first axle 11. The third part 43 is disposed adjacent to the first part 41 in the axial direction L. In the present embodiment, the third part 43 is disposed adjacent to the first part 41 on the first axial side L1.

[0020] The fourth part 44 is configured to form the second axle housing chamber 4C. The fourth part 44 extends along the circumferential direction C so as to surround the second axle 12. The fourth part 44 is disposed adjacent to the second part 42 in the axial direction L. In the present embodiment, the fourth part 44 is disposed adjacent to the second part 42 on the second axial side L2.

[0021] At least one of the first portion 41 and the third portion 43, and the second portion 42 and the fourth portion 44, is integrally formed from an aluminum alloy. In this embodiment, the first portion 41 and the third portion 43 are integrally formed from an aluminum alloy, and the second portion 42 and the fourth portion 44 are integrally formed from an aluminum alloy.

[0022] In this embodiment, the first part 41 and the third part 43, and the second part 42 and the fourth part 44 are formed by casting (for example, die casting). This eliminates processes such as welding, simplifying the manufacturing process of the axle case 4. Furthermore, it increases the degree of freedom in the shape of the axle case 4, making it easier to reduce weight while ensuring the necessary strength of the axle case 4.

[0023] In this embodiment, the third portion 43 and the fourth portion 44 each include a cylindrical portion 51, a first support portion 52, a second support portion 53, and a third support portion 54.

[0024] The cylindrical portion 51 is formed in a cylindrical shape coaxial with the first axle 11 and the second axle 12. In this embodiment, the cylindrical portion 51 of the third portion 43 is formed to extend from the first portion 41 in the first axial direction L1. The cylindrical portion 51 of the third portion 43 is formed with a constant outer diameter from its end on the second axial direction L2 to a predetermined position in the axial direction L, and the outer diameter gradually increases from that position in the axial direction L to the end on the first axial direction L1. The cylindrical portion 51 of the fourth portion 44 is formed to extend from the second portion 42 in the second axial direction L2. The cylindrical portion 51 of the fourth portion 44 is formed with a constant outer diameter from its end on the first axial direction L1 to a predetermined position in the axial direction L, and the outer diameter gradually increases from that position in the axial direction L to the end on the second axial direction L2.

[0025] The first support portion 52 is configured to support the wheel W of the vehicle on which the vehicle drive unit 100 is mounted. In this embodiment, the first support portion 52 is formed in the shape of a plate perpendicular to the axial direction L. A hub bearing (not shown) that rotatably supports the wheel W is attached to the first support portion 52. In this embodiment, the first support portion 52 of the third portion 43 is connected to the end of the cylindrical portion 51 of the third portion 43 on the first axial side L1. The first support portion 52 of the fourth portion 44 is connected to the end of the cylindrical portion 51 of the fourth portion 44 on the second axial side L2.

[0026] The second support portion 53 is configured to support the spring S (for example, a leaf spring) of the axle suspension system in a vehicle on which the vehicle drive unit 100 is mounted. The second support portion 53 is positioned at a distance L in the axial direction from the first support portion 52. In this embodiment, the second support portion 53 of the third portion 43 is positioned at a distance L2 in the axial direction from the first support portion 52 of the third portion 43. The second support portion 53 of the fourth portion 44 is positioned at a distance L1 in the axial direction from the first support portion 52 of the fourth portion 44.

[0027] Furthermore, in this embodiment, the second support portion 53 is formed to protrude upward from the cylindrical portion 51. The second support portion 53 has a mounting surface 53a for placing the spring S, which is formed perpendicular to the vertical direction. In this application, the vehicle drive unit 100 is assumed to be in a state where it is mounted on a vehicle located on the horizontal plane.

[0028] The third support portion 54 is configured to support the shock absorber of the vehicle on which the vehicle drive unit 100 is mounted. The third support portion 54 is formed to protrude laterally (towards the front or rear of the vehicle) from the cylindrical portion 51. In this embodiment, the third support portion 54 of the third part 43 is positioned at a distance L2 in the axial direction from the second support portion 53 of the third part 43. The third support portion 54 of the fourth part 44 is positioned at a distance L1 in the axial direction from the second support portion 53 of the fourth part 44.

[0029] As shown in Figure 2, in this embodiment, the grid ribs 6 are provided on the cylindrical portion 51. The grid ribs 6 are formed in a grid pattern. The grid ribs 6 are arranged over the entire axial direction L of the cylindrical portion 51. The grid ribs 6 are formed to protrude from at least the downward-facing surface on the outer circumferential surface of the cylindrical portion 51. As described above, in this embodiment, since the cylindrical portion 51 is formed in a cylindrical shape, the region on the outer circumferential surface of the cylindrical portion 51 that is located below the axis (axis X) of the cylindrical portion 51 corresponds to at least the downward-facing surface on the outer circumferential surface of the cylindrical portion 51.

[0030] In this embodiment, the lattice rib 6 comprises a plurality of axially extending portions 61 and a plurality of circumferentially extending portions 62.

[0031] Multiple axially extending portions 61 are formed to extend along the axial direction L. Multiple axially extending portions 61 are arranged with gaps between them in the circumferential direction C.

[0032] The multiple circumferentially extending portions 62 are formed to extend along the circumferential direction C. The multiple circumferentially extending portions 62 are arranged with gaps between them in the axial direction L.

[0033] Furthermore, it is preferable to set the size of the grid of the grid ribs 6 (in this case, the area of ​​the rectangular region formed by the intersection of a pair of adjacent axially extending portions 61 and a pair of adjacent circumferentially extending portions 62) to be smaller than the size of the expected stepping stones.

[0034] As shown in Figure 1, in this embodiment, axial ribs 7 are provided on the cylindrical portion 51. The axial ribs 7 are formed to extend along the axial direction L. The axial ribs 7 are located in the region of the cylindrical portion 51 between the first support portion 52 and the second support portion 53 in the axial direction L. In the region of the cylindrical portion 51 between the second support portion 53 and the end of the first support portion 52 opposite to the axial direction L, axial ribs 7 are not provided. In this embodiment, a plurality of axial ribs 7 are arranged at intervals from each other in the circumferential direction C.

[0035] The axial rib 7 is formed to protrude from at least the upward-facing surface on the outer circumferential surface of the cylindrical portion 51. As described above, in this embodiment, since the cylindrical portion 51 is formed in a cylindrical shape, the region on the outer circumferential surface of the cylindrical portion 51 that is located above the axis (axis X) of the cylindrical portion 51 corresponds to at least the upward-facing surface on the outer circumferential surface of the cylindrical portion 51.

[0036] In this embodiment, a plurality of first cooling fins 81 and a plurality of second cooling fins 82 are provided on the axle case 4.

[0037] The multiple first cooling fins 81 are components for dissipating heat transmitted from the drive unit 10. The multiple first cooling fins 81 are formed to extend in the axial direction L. The multiple first cooling fins 81 are arranged across the first portion 41 and the third portion 43. The multiple first cooling fins 81 are provided when the first portion 41 and the third portion 43 are integrally formed. As mentioned above, in this embodiment, the first portion 41 and the third portion 43 are integrally formed from an aluminum alloy.

[0038] The multiple second cooling fins 82 are components for dissipating heat transmitted from the drive unit 10. The multiple second cooling fins 82 are formed to extend in the axial direction L. The multiple second cooling fins 82 are arranged across the second portion 42 and the fourth portion 44. The multiple second cooling fins 82 are provided when the second portion 42 and the fourth portion 44 are integrally formed. As mentioned above, in this embodiment, the second portion 42 and the fourth portion 44 are integrally formed from an aluminum alloy.

[0039] As shown in Figure 3, in this embodiment, each of the multiple first cooling fins 81 is formed in a plate shape extending in the axial direction L and the vertical direction. The multiple first cooling fins 81 are spaced apart from each other in a direction along the horizontal plane and perpendicular to the axial direction L (the vertical direction in Figure 1). In this embodiment, the multiple first cooling fins 81 are arranged to extend from the first portion 41 in the axial direction L1 and to extend upward from the third portion 43.

[0040] Although detailed illustrations are omitted, in this embodiment, each of the multiple second cooling fins 82 is formed in a plate shape extending in the axial direction L and the vertical direction. The multiple second cooling fins 82 are spaced apart from each other in a direction along the horizontal plane and perpendicular to the axial direction L (the vertical direction in Figure 1). In this embodiment, the multiple second cooling fins 82 are arranged to extend from the second portion 42 in the axial direction second side L2 and to extend upward from the fourth portion 44.

[0041] As shown in Figure 4, in this embodiment, the cylindrical portion 51 is formed such that the first thickness t1, which is the thickness at both ends in the direction along its horizontal plane and perpendicular to the axial direction L (left-right direction in Figure 4) (the distance between the inner and outer surfaces of the cylindrical portion 51, excluding the grid ribs 6 and axial ribs 7), is greater than the second thickness t2, which is the thickness at the upper and lower ends. This makes it possible to increase the vertical bending strength of the cylindrical portion 51 while keeping the weight of the cylindrical portion 51 low.

[0042] 2. Second Embodiment In the following description, a vehicle drive unit 100 according to the second embodiment will be explained with reference to Figure 5. In this embodiment, the configuration of the axle case 4 differs from that of the first embodiment. In the following description, the differences from the first embodiment will be the main focus. Unless otherwise specified, the same applies as in the first embodiment.

[0043] As shown in Figure 5, in this embodiment, the second portion 42 and the fourth portion 44 are not integrally formed but are joined to each other by bolt fastening or the like. Therefore, in this embodiment, there are no multiple second cooling fins 82.

[0044] 3. Third Embodiment In the following description, a vehicle drive unit 100 according to the third embodiment will be explained with reference to Figure 6. In this embodiment, the configuration of the axle case 4 differs from that of the first embodiment. In the following description, the differences from the first embodiment will be the main focus. Unless otherwise specified, the same applies as in the first embodiment.

[0045] As shown in Figure 6, in this embodiment, the first portion 41 and the third portion 43 are not integrally formed but are joined to each other by bolt fastening or the like. Therefore, in this embodiment, there are no multiple first cooling fins 81.

[0046] 4. Other Embodiments (1) In the first embodiment described above, a configuration was described as in which the first part 41 and the third part 43, and the second part 42 and the fourth part 44 are formed by casting (for example, die casting). However, the configuration is not limited to such a configuration, and instead of casting, the first part 41 and the third part 43, and the second part 42 and the fourth part 44 may be formed by forging or a 3D printer.

[0047] (2) In the above embodiment, an example was described in which an axial rib 7 formed to extend along the axial direction L is provided on the cylindrical portion 51. However, the embodiment is not limited to such a configuration, and a grid rib configured similarly to the grid rib 6 may be provided instead of the axial rib 7.

[0048] (3) In the above embodiment, a configuration in which the axial rib 7 is arranged in the region between the first support portion 52 and the second support portion 53 in the cylindrical portion 51 and an axial direction L was described as an example. However, the configuration is not limited to such a configuration, and the axial rib 7 may be arranged over the entire axial direction L in the cylindrical portion 51.

[0049] (4) In the above embodiment, the lattice rib 6 was described as having a plurality of axially extending portions 61 formed to extend along the axial direction L and a plurality of circumferentially extending portions 62 formed to extend along the circumferential direction C. However, the lattice rib 6 is not limited to such a configuration, and for example, the lattice rib 6 may have a plurality of first inclined extending portions formed to extend along a direction inclined with respect to the axial direction L and a plurality of second inclined extending portions formed to extend along a direction intersecting the plurality of first inclined extending portions.

[0050] (5) The configurations disclosed in each of the embodiments described above can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. With regard to other configurations, the embodiments disclosed herein are merely illustrative in all respects. Therefore, various modifications can be made as appropriate without departing from the spirit of this disclosure.

[0051] 5. Summary of this embodiment The following describes the vehicle drive system (100) as described above.

[0052] The vehicle drive system (100) is The first axle (11) and the second axle (12) are arranged side by side along the axial direction (L) and each is connected to a wheel (W), A rotating electric machine (2) is the driving force source for the first axle (11) and the second axle (12), A differential gear mechanism (3) distributes the rotation transmitted from the rotating electric machine (2) to the first axle (11) and the second axle (12), It is equipped with an axle case (4) and The axle case (4) is A drive unit housing chamber (4A) housing the drive unit (10) including the rotating electric machine (2) and the differential gear mechanism (3), A first axle housing chamber (4B) that houses at least a portion of the first axle (11), A second axle housing chamber (4C) that houses at least a portion of the second axle (12), The first part (41) and the second part (42) are arranged adjacent to each other in the axial direction (L) and form the drive unit housing chamber (4A), A third portion (43) is positioned adjacent to the first portion (41) in the axial direction (L) and forms the first axle housing chamber (4B), The second part (42) is adjacent to the fourth part (44) in the axial direction (L) and forms the second axle housing chamber (4C), At least one of the first portion (41) and the third portion (43), and the second portion (42) and the fourth portion (44) are integrally formed from an aluminum alloy.

[0053] In this configuration, at least one of the first part (41) and the third part (43) of the axle case (4), and the second part (42) and the fourth part (44) of the axle case (4) are integrally formed from an aluminum alloy. This makes it easier to reduce the weight of the axle case (4) compared to, for example, a case where the axle case (4) is made of an alloy mainly composed of iron. In addition, the number of joints in the axle case (4) can be reduced compared to a configuration where the first part (41) and the third part (43) are separate, and the second part (42) and the fourth part (44) are separate. Therefore, in addition to reducing the weight of the axle case (4), it is also easier to ensure the strength of the axle case (4).

[0054] Here, each of the third portion (43) and the fourth portion (44) includes a cylindrical portion (51) formed in a cylindrical shape coaxial with the first axle (11) and the second axle (12), It is preferable that the grid ribs (6) are formed in a grid pattern and protrude from at least the downward-facing surface on the outer circumferential surface of the cylindrical portion (51), and are provided over the entire area of ​​the cylindrical portion (51) in the axial direction (L).

[0055] With this configuration, the lattice ribs (6) make it easier to ensure the strength of the cylindrical portion (51) and to avoid contact between flying stones and the outer surface of the cylindrical portion (51). In addition, the lattice ribs (6) make it easier to ensure heat dissipation from the axle case (4) to the outside.

[0056] In the above configuration, each of the third portion (43) and the fourth portion (44) further comprises a first support portion (52) that supports the wheel (W), and a second support portion (53) that is positioned spaced apart from the first support portion (52) in the axial direction (L) and supports the spring (S) of the axle suspension device. It is preferable that the axial ribs (7) formed to protrude from at least the upward-facing surface on the outer circumferential surface of the cylindrical portion (51) and extend along the axial direction (L) are provided in the region of the cylindrical portion (51) between the first support portion (52) and the second support portion (53) in the axial direction (L).

[0057] In this configuration, axial ribs (7) are provided in the region between the first support portion (52) and the second support portion (53) in the cylindrical portion (51), where stress is likely to act, in the axial direction (L). This allows for a reduction in the area where the axial ribs (7) are placed, thereby reducing the weight of the axle case (4) while increasing the strength of the cylindrical portion (51). In addition, the axial ribs (7) facilitate heat dissipation from the axle case (4) to the outside.

[0058] Furthermore, if the first portion (41) and the third portion (43) are integrally formed, a plurality of first cooling fins (81) for dissipating heat transmitted from the drive unit (10) are provided so as to extend in the axial direction (L) across the first portion (41) and the third portion (43). When the second portion (42) and the fourth portion (44) are integrally formed, it is preferable that a plurality of second cooling fins (82) for dissipating heat transmitted from the drive unit (10) are provided so as to extend in the axial direction (L) across the second portion (42) and the fourth portion (44).

[0059] With this configuration, if the first part (41) and the third part (43) are integrally formed, the multiple first cooling fins (81) can not only dissipate heat transmitted from the drive unit (10) but also ensure the strength of the first part (41) and the third part (43). Furthermore, if the second part (42) and the fourth part (44) are integrally formed, the multiple second cooling fins (82) can not only dissipate heat transmitted from the drive unit (10) but also ensure the strength of the second part (42) and the fourth part (44). [Industrial applicability]

[0060] The technology described herein can be used in a vehicle drive system comprising a first axle and a second axle arranged side by side along the axial direction and each connected to a wheel, a rotating electric machine which is the driving force source for them, a differential gear mechanism which distributes the rotation transmitted from the rotating electric machine to the first axle and the second axle, and an axle case. [Explanation of symbols]

[0061] 100: Vehicle drive unit, 10: Drive unit, 11: First axle, 12: Second axle, 2: Rotating electric machine, 3: Differential gear mechanism, 4: Axle case, 4A: Drive unit housing chamber, 4B: First axle housing chamber, 4C: Second axle housing chamber, 41: First part, 42: Second part, 43: Third part, 44: Fourth part, 51: Cylindrical part, 52: First support part, 53: Second support part, 6: Lattice rib, 7: Axial rib, 81: First cooling fin, 82: Second cooling fin, L: Axial

Claims

1. The first and second axles are arranged side by side along the axial direction, and each is connected to a wheel. A rotating electric machine which is the driving force source for the first axle and the second axle, A differential gear mechanism that distributes the rotation transmitted from the rotating electric machine to the first axle and the second axle, Equipped with an axle case, The aforementioned axle case is A drive unit housing chamber housing the drive unit including the rotating electric machine and the differential gear mechanism, A first axle housing chamber that houses at least a portion of the first axle, A second axle housing chamber that houses at least a portion of the second axle, The first and second parts are arranged adjacent to each other in the axial direction and form the drive unit housing chamber, A third portion is positioned adjacent to the first portion in the axial direction and forms the first axle housing chamber, It comprises a fourth portion which is positioned adjacent to the second portion in the axial direction and forms the second axle housing chamber, A vehicle drive system in which at least one of the first and third parts and the second and fourth parts is integrally formed from an aluminum alloy.

2. Each of the third and fourth portions comprises a cylindrical portion formed in a cylindrical shape that is coaxial with the first and second axles, The vehicle drive device according to claim 1, wherein grid ribs, formed in a grid pattern and protruding from at least the downward-facing surface of the outer circumferential surface of the cylindrical portion, are provided over the entire axial area of ​​the cylindrical portion.

3. Each of the third and fourth parts further comprises a first support portion for supporting the wheel, and a second support portion positioned axially spaced from the first support portion for supporting the spring of the axle suspension system. The vehicle drive device according to claim 2, wherein an axial rib, formed to protrude from at least an upward-facing surface on the outer circumferential surface of the cylindrical portion and to extend along the axial direction, is provided in the region of the cylindrical portion between the first support portion and the second support portion in the axial direction.

4. When the first portion and the third portion are integrally formed, a plurality of first cooling fins for dissipating heat transmitted from the drive unit are provided so as to extend axially across the first portion and the third portion. If the second portion and the fourth portion are integrally formed, a plurality of second cooling fins for dissipating heat transmitted from the drive unit are provided so as to extend axially across the second portion and the fourth portion, according to any one of claims 1 to 3.

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