Drive unit

Abstract

This suppresses the mass imbalance between the left and right sides of the drive unit. [Solution] The drive unit for a vehicle comprises a first motor, a first reduction gear, a first inverter, a second motor, a second reduction gear, and a second inverter, a locking mechanism for mechanically locking and unlocking the first reduction gear, and a casing housing these components. The casing has a first portion located on one side of a pair of left and right wheels when the drive unit is mounted on a vehicle, and a second portion located on the other side of the pair of left and right wheels. The first motor, first reduction gear, first inverter, and locking mechanism are located in the first portion of the casing, and the second motor, second reduction gear, and second inverter are located in the second portion of the casing. The motor center plane that equally divides the space between the first motor and the second motor may be offset towards the second portion of the casing with respect to the inverter center plane that equally divides the space between the first inverter and the second inverter.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a drive unit for a vehicle.

Background Art

[0002] Patent Document 1 describes a drive unit for a vehicle. The drive unit includes two motors and two speed reducers, and independently drives a pair of left and right wheels respectively.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above drive unit, two motors and two speed reducers are arranged symmetrically left and right. Thus, in a drive unit that independently drives a pair of left and right wheels, it is desirable to arrange the component pairs such as motors and speed reducers in a well - balanced manner left and right. However, the components of the drive unit include those that do not form a pair, such as a lock mechanism. The lock mechanism, also referred to as, for example, a parking lock, is provided for one of the two speed reducers and is configured to lock and unlock the said one speed reducer. The presence of the lock mechanism can cause an imbalance in mass with respect to left and right in the drive unit. This specification provides a technology that can suppress such an imbalance.

Means for Solving the Problems

[0005] The technology disclosed herein is embodied in a drive unit for a vehicle that independently drives a pair of left and right wheels. The drive unit comprises a first motor for driving one of the pair of left and right wheels, a first reduction gear for reducing the rotation of the first motor, a first inverter electrically connected to the first motor, a second motor for driving the other of the pair of left and right wheels, a second reduction gear for reducing the rotation of the second motor, a second inverter electrically connected to the second motor, a locking mechanism for mechanically locking and unlocking the first reduction gear, and a casing housing the first motor, the first reduction gear, the first inverter, the second motor, the second reduction gear, the second inverter, and the locking mechanism, wherein the casing comprises the drive unit When the casing is mounted on a vehicle, it has a first portion located on one side of the pair of left and right wheels, and a second portion located on the other side of the pair of left and right wheels, wherein the first motor, the first reduction gear, the first inverter, and the locking mechanism are located in the first portion of the casing, and the second motor, the second reduction gear, and the second inverter are located in the second portion of the casing, and the motor center plane that equally divides the space between the first motor and the second motor may be offset toward the second portion of the casing with respect to the inverter center plane that equally divides the space between the first inverter and the second inverter.

[0006] In the drive unit described above, the first motor, first reduction gear, first inverter, and locking mechanism are located in the first part of the casing (i.e., one side of the pair of left and right wheels), while the second motor, second reduction gear, and second inverter are located in the second part of the casing (i.e., the other side of the pair of left and right wheels). In other words, the locking mechanism exists only in the first part of the casing, and there is no corresponding configuration in the second part of the casing. Therefore, in the drive unit described above, the first motor and the second motor are positioned such that the overall center of gravity of the first and second motors is offset towards the second part with respect to the inverter center plane that equally divides the space between the first and second inverters. More specifically, the motor center plane that equally divides the space between the first and second motors is offset towards the second part of the casing with respect to the inverter center plane that equally divides the space between the first and second inverters. This makes it possible to suppress the mass imbalance between the left and right sides of the drive unit, even when a locking mechanism is present in the drive unit. [Brief explanation of the drawing]

[0007] [Figure 1] A block diagram showing a vehicle as viewed from above. [Figure 2] This is a schematic diagram showing the drive unit. [Figure 3] The electrical circuit diagram of the drive unit is shown. [Figure 4] This is a diagram showing the configuration of the locking mechanism. [Figure 5] This is an enlarged view of section V in Figure 2. [Modes for carrying out the invention]

[0008] In a first aspect of this technology, as previously described, the drive unit is a vehicle drive unit that independently drives a pair of left and right wheels. The drive unit comprises a first motor that drives one of the pair of left and right wheels, a first reduction gear that reduces the rotation of the first motor, a first inverter electrically connected to the first motor, a second motor that drives the other of the pair of left and right wheels, a second reduction gear that reduces the rotation of the second motor, a second inverter electrically connected to the second motor, a locking mechanism that mechanically locks and unlocks the first reduction gear, and a casing that houses the first motor, the first reduction gear, the first inverter, the second motor, the second reduction gear, the second inverter, and the locking mechanism, wherein the casing is the drive unit When mounted on a vehicle, the casing has a first portion located on one side of the pair of left and right wheels, and a second portion located on the other side of the pair of left and right wheels, wherein the first motor, the first reduction gear, the first inverter, and the locking mechanism are located in the first portion of the casing, and the second motor, the second reduction gear, and the second inverter are located in the second portion of the casing, and the motor center plane that equally divides the space between the first motor and the second motor may be offset toward the second portion of the casing with respect to the inverter center plane that equally divides the space between the first inverter and the second inverter.

[0009] In a second aspect of this technology, in addition to the first aspect described above, the casing may have a first oil pan provided at the lower part of the first portion and a second oil pan provided at the lower part of the second portion. The oil pan center plane that equally divides the space between the first oil pan and the second oil pan may be offset with respect to the motor center plane towards the first portion of the casing. With this configuration, the first oil pan and the second oil pan can be positioned such that the center of gravity of the entire first and second oil pans is offset with respect to the motor center plane towards the first portion. This makes it possible to suppress the mass imbalance between the left and right sides of the drive unit.

[0010] In a third aspect of this technology, in addition to the first or second aspect described above, the drive unit may be connected to a first drive shaft connected to one of the pair of left and right wheels, and a second drive shaft connected to the other of the pair of left and right wheels. In this case, the center of gravity of the drive unit may be located on an inboard center plane that equally divides the space between the first drive shaft inboard of the first drive shaft and the second drive shaft inboard of the second drive shaft. With this configuration, when mounting the drive unit on a vehicle, the first drive shaft and the second drive shaft can be of equal length to each other so that the center of gravity of the drive unit is located on a vehicle center plane that equally divides the space between the left wheel and the right wheel. This improves the driving performance of the vehicle.

[0011] In a fourth aspect of this technology, in addition to any one of the first to third aspects described above, the drive unit may further include a first terminal block fixed to the casing, a first conductive path electrically connecting the first inverter and the first motor via the first terminal block, a second terminal block fixed to the casing, and a second conductive path electrically connecting the second inverter and the second motor via the second terminal block. In this case, the total length of the first conductive path and the total length of the second conductive path may be different from each other. On the other hand, the length of the section of the first conductive path from the first motor to the first terminal block and the length of the section of the second conductive path from the second motor to the second terminal block may be equal to each other. With such a configuration, the design can be standardized between the section of the first conductive path from the first motor to the first terminal block and the section of the second conductive path from the second motor to the second terminal block. These sections are adjacent to the first motor or the second motor, respectively, and require relatively high strength and durability. If the design of such sections can be standardized, it becomes easier to satisfy the required strength and durability for both the first and second conductive paths, even if the total lengths of the first and second conductive paths are different.

[0012] In a fifth aspect of this technology, in addition to any one of the first to fourth aspects described above, the first motor and the second motor may be arranged symmetrically with respect to the motor center plane. With such a configuration, the mass imbalance on the left and right sides of the drive unit can be effectively suppressed. However, in another embodiment, the first motor and the second motor do not necessarily have to be arranged symmetrically with respect to the motor center plane.

[0013] In a sixth aspect of this technology, in addition to any one of the first to fifth aspects described above, the first inverter and the second inverter may be arranged symmetrically with respect to the inverter center plane. With such a configuration, the mass imbalance on the left and right sides of the drive unit can be effectively suppressed. However, in another embodiment, the first inverter and the second inverter do not necessarily have to be arranged symmetrically with respect to the inverter center plane.

[0014] In a seventh aspect of the present technology, in addition to any one of the first to sixth aspects described above, the casing may include a first motor chamber located in the first part and housing the first motor and the first reduction gear, a second motor chamber located in the second part and housing the second motor and the second reduction gear, and a motor chamber partition wall located on the motor center plane and at least partially separating the first motor chamber and the second motor chamber.

[0015] In an eighth aspect of the present technology, in addition to any one of the first to seventh aspects described above, the casing may further include a first inverter chamber located in the first part and housing the first inverter, a second inverter chamber located in the second part and housing the second inverter, and an inverter chamber partition wall located on the inverter center plane and at least partially separating the first inverter chamber and the second inverter chamber.

[0016] In a ninth aspect of this technology, in addition to any one of the first to eighth aspects described above, the locking mechanism may be provided on the rotating shaft connecting the first motor and the first reduction gear. With this configuration, the torque acting on the locking mechanism when locking the first reduction gear can be made relatively small. However, in another embodiment, the locking mechanism may be provided on the rotating shaft on one side of the pair of left and right wheels rather than on the first reduction gear.

[0017] In a tenth aspect of this technology, in addition to the ninth aspect described above, the locking mechanism may include a locking gear fixed to the rotating shaft and a locking pawl movable between a locked position in which it engages with the locking gear and an unlocked position in which it is disengaged from the locking gear.

[0018] Hereinafter, representative and non-limiting examples of the present invention will be described in detail with reference to the drawings. This detailed description is simply intended to show those skilled in the art details for carrying out preferred examples of the present invention and is not intended to limit the scope of the present invention. Furthermore, additional features and inventions disclosed below may be used separately from or in conjunction with other features and inventions to provide a further improved drive unit.

[0019] Furthermore, the combinations of features and processes disclosed in the following detailed description are not essential for carrying out the present invention in the broadest sense, and are described solely to illustrate representative examples of the present invention. Moreover, the various features of the representative examples described above and below, as well as the various features described in the independent and dependent claims, do not necessarily have to be combined in the same way as the examples described herein or in the order listed, in order to provide additional and useful embodiments of the present invention.

[0020] All features described in this specification and / or the claims are intended to be disclosed separately and independently of one another, as limitations to the original disclosure as well as the claimed subject matter, apart from the configuration of the features described in the embodiments and / or claims. Further, all descriptions of numerical ranges and groups or collections are made with the intention of disclosing intermediate configurations, as limitations to the original disclosure as well as the claimed subject matter.

[0021] (Example) Referring to the drawings, the drive unit 20 for a vehicle according to an example will be described. As shown in FIG. 1, the drive unit 20 of this example can be mounted on the vehicle 10. The vehicle 10 is an electric vehicle driven by a motor. Here, each direction of the drive unit 20 in the drawings conforms to the direction when mounted on the vehicle 10, that is, the direction of the vehicle 10. The direction FR indicates the front in the longitudinal direction of the vehicle 10, and the negative direction RR of the direction FR indicates the rear in the longitudinal direction of the vehicle 10. The direction LH indicates the left in the left-right direction (also referred to as the vehicle width direction) of the vehicle 10, and the negative direction RH of the direction LH indicates the right in the left-right direction of the vehicle. The direction UP indicates the upper in the up-down direction (also referred to as the vehicle height direction) of the vehicle 10, and the negative direction DW of the direction UP indicates the lower in the up-down direction of the vehicle 10.

[0022] The drive unit 20 is mounted on the vehicle 10 so as to be divided by a vehicle center plane VC that equally divides between the left wheel 14L and the right wheel 14R. A first drive shaft 16L, which is a left drive shaft, is connected to the drive unit 20. The first drive shaft 16L is connected to the left wheel 14L disposed at the front portion of the vehicle body 12 of the vehicle 10. A second drive shaft 16R, which is a right drive shaft, is connected to the drive unit 20. The second drive shaft 16R is connected to the right wheel 14R disposed at the front portion of the vehicle body 12 of the vehicle 10. As will be described later, the drive unit 20 is configured to drive the pair of left and right wheels 14L, 14R independently. In a modification, the drive unit 20 may drive a pair of left and right wheels 15L, 15R disposed at the rear portion of the vehicle body 12. Electric power for driving the pair of left and right wheels 14L, 14R is supplied to the drive unit 20 from, for example, a battery 18 disposed under the floor of the vehicle 10.

[0023] The drive unit 20 includes a first motor 22, a first speed reducer 24, a lock mechanism 26, a first inverter 30, a second motor 42, a second speed reducer 44, a second inverter 50, and a casing 60. The casing 60 houses the first motor 22, the first speed reducer 24, the first inverter 30, the lock mechanism 26, the second motor 42, the second speed reducer 44, and the second inverter 50.

[0024] As shown in FIG. 2, when the casing 60 is mounted on the vehicle 10, it is divided into a first portion C1 located on the left wheel 14L side of the vehicle 10 and a second portion C2 located on the right wheel 14R side of the vehicle 10. The first motor 22, the first speed reducer 24, the first inverter 30, and the lock mechanism 26 are disposed in the first portion C1. The second motor 42, the second speed reducer 44, and the second inverter 50 are disposed in the second portion C2.

[0025] The first motor 22 is connected to the first drive shaft inboard 16aL of the first drive shaft 16L via the first reduction gear 24. The second motor 42 is connected to the second drive shaft inboard 16aR of the second drive shaft 16R via the second reduction gear 44.

[0026] The first motor 22 is an electric motor and is the prime mover for driving the left wheel 14L. The rotating shaft 28 (i.e., motor shaft) of the first motor 22 is rotatably supported in the casing 60 via a bearing 21. The second motor 42 is an electric motor and is the prime mover for driving the right wheel 14R. The second motor 42 has the same configuration (or a symmetrical configuration) as the first motor 22. The rotating shaft 48 (i.e., motor shaft) of the second motor 42 is rotatably supported in the casing 60 via a bearing 41. The first motor 22 and the second motor 42 are arranged coaxially. That is, the rotating shaft 28 of the first motor 22 and the rotating shaft 48 of the second motor 42 are arranged on the same straight line.

[0027] As shown in Figure 2, the first reduction gear 24 is connected to the rotating shaft 28 of the first motor 22. The first reduction gear 24 reduces the rotation of the first motor 22. The first reduction gear 24 has a planetary gear mechanism arranged coaxially with the first motor 22. Specifically, the first reduction gear 24 has a sun gear 24a, a plurality of planetary gears 24b, an internal gear 24c, and a planetary carrier 24d. The sun gear 24a is connected to the rotating shaft 28 of the first motor 22. The internal gear 24c is fixed to the casing 60. The plurality of planetary gears 24b are located between the sun gear 24a and the internal gear 24c and are configured to mesh with both the sun gear 24a and the internal gear 24c. The planetary carrier 24d rotatably supports each of the plurality of planetary gears 24b and is also rotatably supported by the casing 60. As a result, the planetary carrier 24d holds multiple planetary gears 24b so that they can rotate and revolve. The first drive shaft inboard 16aL is connected to the planetary carrier 24d. This planetary gear mechanism allows the first reduction gear 24 to increase the torque output to the left wheel 14L in response to the torque input from the first motor 22.

[0028] The second reduction gear 44 is connected to the rotating shaft 48 of the second motor 42. The second reduction gear 44 reduces the rotation of the second motor 42. The second reduction gear 44 has a configuration symmetrical to the first reduction gear 24. That is, the second reduction gear 44 has a planetary gear mechanism arranged coaxially with the second motor 42. Specifically, the second reduction gear 44 has a sun gear 44a, a plurality of planetary gears 44b, an internal gear 44c, and a planetary carrier 44d. The sun gear 44a is connected to the rotating shaft 48 of the second motor 42. The internal gear 44c is fixed to the casing 60. The plurality of planetary gears 44b are located between the sun gear 44a and the internal gear 44c and are configured to mesh with both the sun gear 44a and the internal gear 44c. The planetary carrier 44d rotatably supports each of the plurality of planetary gears 44b and is also rotatably supported by the casing 60. As a result, the planetary carrier 44d holds multiple planetary gears 44b so that they can rotate and revolve. The second drive shaft inboard 16aR is connected to the planetary carrier 44d. This planetary gear mechanism allows the second reduction gear 44 to increase the torque output to the right wheel 14R in response to the torque input from the second motor 42.

[0029] As shown in Figures 2 and 3, the first inverter 30 is a three-phase (U-phase, V-phase, W-phase) AC inverter having a plurality (six in this embodiment) of switching elements 30a. Each switching element 30a is, for example, an RC-IGBT element. The first inverter 30 is electrically connected to the first motor 22. The battery 18 is electrically connected to the first inverter 30. Therefore, the first inverter 30 can convert the DC power supplied from the battery 18 into three-phase AC power and supply it to the first motor 22. Although not shown, the first inverter 30 is fixed to the first part C1 of the casing 60.

[0030] The second inverter 50 is a three-phase AC inverter configured similarly to the first inverter 30. The second inverter 50 is electrically connected to the second motor 42. The battery 18 is electrically connected to the second inverter 50. Therefore, the second inverter 50 can convert the DC power supplied from the battery 18 into three-phase AC power and supply it to the second motor 42. The second inverter 50 is connected in parallel with the first inverter 30. Although not shown in the diagram, the second inverter 50 is fixed to the second part C2 of the casing 60.

[0031] While not particularly limited, DC-DC converters 70 are connected between the first inverter 30 and the battery 18, and between the first inverter 30 and the second inverter 50. The DC-DC converter 70 boosts the DC power supplied from the battery 18 and supplies the boosted DC power to the first inverter 30 and the second inverter 50, respectively. The DC-DC converter 70 has a pair of switching elements 70a and a coil 70b. Each switching element 70a is an RC-IGBT similar to the switching element 50a of the first inverter 30. One end of the pair of switching elements 70a is connected to the positive terminal of the battery 18 via the coil 70b, and the other end is connected to the first inverter and the second inverter, respectively. The other end of the pair of switching elements 70a is connected between the battery 18 and the first and second inverters, and the other end is connected to the negative terminal of the battery 18 via the coil 70b. For example, a capacitor 72 is placed between the battery 18 and the DC-DC converter 70, and a capacitor 74 is placed between the DC-DC converter 70 and the first inverter 30 and the second inverter 50.

[0032] As shown in Figures 2 and 4, the locking mechanism 26 mechanically locks and unlocks the first reduction gear 24. The locking mechanism 26 is a mechanical lock used when parking a vehicle and is also called a parking lock. The locking mechanism 26 has a locking gear 26g and a locking pole 26p. The locking gear 26g is fixed, for example, to the rotating shaft 28 of the first motor 22. The locking pole 26p is configured to be movable between a locked position P1 in which it engages with the locking gear 26g and an unlocked position P2 in which it is disengaged from the locking gear 26g. The locking pole 26p is rotatably supported by the casing body 61 of the casing 60 via a rotating shaft 26a. The locking pole 26p is configured to be movable by an actuator having a cam 27 and an electric motor (not shown). The cam 27 is, for example, an elliptical or egg-shaped plate member. As the cam 27 rotates around the rotation shaft 27a by the electric motor, the lock pole 26p is switched between a locked position P1 and an unlocked position P2. For example, when the cam 27 rotates in the direction of the arrow from the position shown in Figure 4, the lock pole 26p moves from the locked position P1 to the lower unlocked position P2. The lock mechanism 26 is provided on the rotation shaft 28 that connects the first motor 22 and the first reduction gear 24, although this is not a limiting factor. With this configuration, the torque acting on the lock mechanism 26 when locking the first reduction gear 24 can be made relatively small. However, the position in which the lock mechanism 26 is provided is not limited to this, and the lock mechanism 26 may be provided on the left wheel 14L side of the first reduction gear 24 (i.e., on the output shaft of the first reduction gear 24).

[0033] The details of the casing 60 will be described with reference to Figures 2 and 5. As shown in Figure 2, the casing 60 has a first motor chamber MR1, a second motor chamber MR2, a first inverter chamber IR1, and a second inverter chamber IR2. The first motor chamber MR1 is located in the first part C1 of the casing 60 and houses the first motor 22 and the first reduction gear 24. As mentioned above, the locking mechanism 26 is provided on the rotating shaft 28 between the first motor 22 and the first reduction gear 24, so the locking mechanism 26 is also housed in the first motor chamber MR1. The second motor chamber MR2 is located in the second part C2 and houses the second motor 42 and the second reduction gear 44. The first inverter chamber IR1 is located in the first part C1 and houses the first inverter 30. The second inverter chamber IR2 is located in the second part C2 and houses the second inverter 50. However, in the modified configuration, the DC-DC converter 70 may be housed in at least one of the first inverter chamber IR1 and the second inverter chamber IR2.

[0034] The casing 60 is a housing component. The casing 60 is made of metal. The casing 60 has a casing body 61 that is open downwards, and two oil pans 62 and 64 that cover the casing body 61 from below. The casing body 61 has an upper wall 61a, a peripheral wall 61b, a first partition wall 61c, a second partition wall 61d, and a third partition wall 61e. The peripheral wall 61b extends downwards from the periphery of the upper wall 61a.

[0035] The first bulkhead 61c extends within the peripheral wall 61b in a planar direction perpendicular to the vertical direction (i.e., in the left-right and front-back directions), separating the motor rooms MR1 ​​and MR2 from the inverter rooms IR1 and IR2.

[0036] The second partition wall 61d is located on the motor center plane MC that equally divides the space between the first motor 22 and the second motor 42. The first motor 22 is rotatably supported on the left side of the second partition wall 61d. The second motor 42 is rotatably supported on the right side of the second partition wall 61d. The second partition wall 61d extends to at least one of the oil pans 62 and 64. The second partition wall 61d completely isolates the first motor chamber MR1 and the second motor chamber MR2. With this configuration, the movement of lubricating oil between the first motor chamber MR1 and the second motor chamber MR2 can be prevented, and the left-right mass imbalance of the drive unit 20 caused by the movement of lubricating oil between the first motor chamber MR1 and the second motor chamber MR2 can be suppressed. In a modified version, the second partition wall 61d may partially isolate the first motor chamber MR1 and the second motor chamber MR2. In another modified version, the casing body 61 may not have the second partition wall 61d. In this case, the first motor 22 and the second motor 42 may each be rotatably supported on another part of the casing body 61.

[0037] The third partition wall 61e is located on the inverter center plane IvC that equally divides the space between the first inverter 30 and the second inverter 50. The third partition wall 61e partially separates the first inverter chamber IR1 and the second inverter chamber IR2. In a modified example, the third partition wall 61e may completely separate the first inverter chamber IR1 and the second inverter chamber IR2. In another modified example, the casing body 61 may not have the third partition wall 61e.

[0038] In this embodiment, the inverter center plane IvC coincides with the vehicle center plane VC. In the modified example, the inverter center plane IvC does not have to coincide with the vehicle center plane VC.

[0039] The second partition wall 61d and the third partition wall 61e are examples of the "motor room partition wall" and "inverter room partition wall" according to the technology of this specification.

[0040] As shown in Figure 5, two oil pans 62 and 64 are provided at the bottom of the casing 60. The casing 60 has two openings 60a and 60b defined by the peripheral wall 61b and the second partition wall 61d. The two openings 60a and 60b include a first opening 60a located on the first portion C1 side and a second opening 60b located on the second portion C2 side. The two oil pans 62 and 64 include a first oil pan 62 that closes the first opening 60a and a second oil pan 64 that closes the second opening 60b. Each of the two oil pans 62 and 64 is fastened to the casing body 61, for example, by a number of bolts (not shown).

[0041] Each of the two oil pans 62 and 64 is formed to store lubricating oil for the first motor chamber MR1 and the second motor chamber MR2, respectively. The first oil pan 62 has a bottom wall 62a and a peripheral wall 62b extending upward from the periphery of the bottom wall 62a. The second oil pan 64 has a bottom wall 64a and a peripheral wall 64b extending upward from the periphery of the bottom wall 64a. The volume of the second oil pan 64 is larger than the volume of the first oil pan 62. Specifically, the left-right dimension (i.e., width dimension) W2 of the second oil pan 64 is larger than the left-right dimension (i.e., width dimension) W1 of the first oil pan 62. The front-rear dimension of the first oil pan 62 is approximately equal to the front-rear dimension of the second oil pan 64. In the modified example, the volumes of the first oil pan 62 and the second oil pan 64 may be equal, and the left-right dimensions W1 and W2 of the first oil pan 62 and the second oil pan 64 may be equal.

[0042] As shown in Figure 2, in this embodiment, the motor center plane MC is offset to the second portion C2 side of the casing 60 with respect to the inverter center plane IvC, such that the center of gravity 20g of the drive unit 20 is located on the inboard center plane IbC that equally divides the space between the first drive shaft inboard 16aL and the second drive shaft inboard 16aR.

[0043] In this embodiment, the inboard center plane IbC coincides with the vehicle center plane VC. In the modified example, the inboard center plane IbC does not have to coincide with the vehicle center plane VC.

[0044] Furthermore, in this embodiment, the oil pan center plane OC, which equally divides the space between the first oil pan 62 and the second oil pan 64, is offset from the motor center plane MC towards the first portion C1 of the casing 60, so that the center of gravity 20g of the drive unit 20 lies on the inboard center plane IbC.

[0045] In the drive unit 20 of this embodiment, the first motor 22, the first reduction gear 24, the first inverter 30, and the locking mechanism 26 are located in the first part C1 of the casing 60 (i.e., the left wheel 14L side), while the second motor 42, the second reduction gear 44, and the second inverter 50 are located in the second part C2 of the casing 60 (i.e., the right wheel 14R side). That is, the locking mechanism 26 is present only in the first part C1 of the casing 60, and there is no corresponding configuration in the second part C2 of the casing 60. Therefore, in the drive unit 20 described above, the first motor 22 and the second motor 42 are positioned such that the overall center of gravity of the first motor 22 and the second motor 42 is offset towards the second part C2 side with respect to the inverter center plane IvC. Specifically, the motor center plane MC is offset towards the second part C2 side of the casing 60 with respect to the inverter center plane IvC. This makes it possible to suppress the mass imbalance between the left and right sides of the drive unit 20, even when the drive unit 20 has a locking mechanism 26.

[0046] Furthermore, in this embodiment, the first motor 22 and the second motor 42 are arranged substantially symmetrically with respect to the motor center plane MC. With this configuration, the left-right mass imbalance of the drive unit 20 can be effectively suppressed. However, in modified examples, the first motor 22 and the second motor 42 do not necessarily have to be arranged substantially symmetrically with respect to the motor center plane MC.

[0047] Furthermore, in this embodiment, the oil pan center plane OC is offset relative to the motor center plane MC towards the first portion C1 of the casing 60. With this configuration, the first oil pan 62 and the second oil pan 64 can be positioned such that the overall center of gravity of the first oil pan 62 and the second oil pan 64 is offset relative to the motor center plane MC towards the first portion C1. This makes it possible to suppress the mass imbalance between the left and right sides of the drive unit 20.

[0048] Furthermore, in this embodiment, the first inverter 30 and the second inverter 50 are arranged substantially symmetrically with respect to the inverter center plane IvC. With this configuration, the left-right mass imbalance of the drive unit 20 can be effectively suppressed. However, in modified examples, the first inverter 30 and the second inverter 50 do not necessarily have to be arranged symmetrically with respect to the inverter center plane IvC.

[0049] Furthermore, in this embodiment, the center of gravity 20g of the drive unit 20 is located on the inboard center plane IbC. With this configuration, when mounting the drive unit 20 on the vehicle 10 such that the center of gravity 20g of the drive unit 20 is located on the vehicle center plane VC, the first drive shaft 16L and the second drive shaft 16R can be of equal length. This improves the driving performance of the vehicle 10.

[0050] As shown in Figures 2 and 3, the drive unit 20 comprises a plurality of first conductive paths 31u, 31v, 31w, a first terminal block 32, a plurality of second conductive paths 51u, 51v, 51w, and a second terminal block 52. The plurality of first conductive paths 31u, 31v, 31w electrically connect the first motor 22 and the first inverter 30. The plurality of first conductive paths 31u, 31v, 31w include a U-phase conductive path 31u, a V-phase conductive path 31v, and a W-phase conductive path 31w. AC power with different phases flows through the U-phase conductive path 31u, the V-phase conductive path 31v, and the W-phase conductive path 31w. Each of the plurality of first conductive paths 31u, 31v, 31w is formed using, for example, metal. The U-phase conductive path 31u extends via the first terminal block 32. The first terminal block 32 is fixed to the first partition wall 61c of the casing 60. Therefore, the intermediate portion of the U-phase conductive path 31u is fixed to the casing 60 using the first terminal block 32. The first terminal block 32 is formed, for example, from resin. The U-phase conductive path 31u has a first section 34, a second section 36, and a relay section 35 that relays between the first section 34 and the second section 36. The first section 34 extends from the first motor 22 to the first terminal block 32. The second section 36 extends from the first terminal block 32 to the first inverter 30. The relay section 35 is provided on the first terminal block 32. Each section 34, 35, and 36 is made of a different material. Although not shown in Figure 2, the V-phase conductive path 31v and the W-phase conductive path 31w are configured similarly to the U-phase conductive path 31u.

[0051] Multiple second conductive paths 51u, 51v, and 51w electrically connect the second motor 42 and the second inverter 50. The multiple second conductive paths 51u, 51v, and 51w are configured similarly to the multiple first conductive paths 31u, 31v, and 31w, and include a U-phase conductive path 51u, a V-phase conductive path 51v, and a W-phase conductive path 51w. The U-phase conductive path 51u extends via a second terminal block 52. The second terminal block 52 is fixed to the first partition wall 61c of the casing 60. Therefore, the intermediate portion of the U-phase conductive path 51u is fixed to the casing 60 using the second terminal block 52. The second terminal block 52 is formed, for example, from resin. The U-phase conductive path 51u has a first section 54, a second section 56, and a relay section 55 that relays between the first section 54 and the second section 56. The first section 54 extends from the second motor 42 to the second terminal block 52. The second section 56 extends from the second terminal block 52 to the second inverter 50. The relay section 55 is located at the second terminal block 52. Each section 54, 55, and 56 is composed of separate components. Although not shown in Figure 2, the V-phase conductive path 51v and the W-phase conductive path 51w are configured in the same way as the U-phase conductive path 51u.

[0052] The total lengths of each of the multiple first conductive paths 31u, 31v, and 31w are different from the total lengths of each of the multiple second conductive paths 51u, 51v, and 51w. On the other hand, the lengths of the first sections 34 of each of the multiple first conductive paths 31u, 31v, and 31w are equal to the lengths of the first sections 54 of the multiple second conductive paths 51u, 51v, and 51w. With this configuration, the design can be standardized between the first sections 34 of the multiple first conductive paths 31u, 31v, and 31w and the first sections 54 of the multiple second conductive paths 51u, 51v, and 51w. These first sections 34 and 54 are sections that are close to the first motor 22 or the second motor 42, respectively, and require relatively high strength and durability. If the design of such first sections 34 and 54 can be standardized, it becomes easier to satisfy the required strength and durability of the multiple first conductive paths 31u, 31v, and 31w and the multiple second conductive paths 51u, 51v, and 51w, even if the total lengths of each of the multiple first conductive paths 31u, 31v, and 31w and the multiple second conductive paths 51u, 51v, and 51w differ from each other.

[0053] In this embodiment, the locking mechanism 26 is located in the first portion C1 of the casing 60. However, the position of the locking mechanism 26 is not limited to this. The locking mechanism may be located in the second portion C2 instead of the first portion C1, and the locking mechanism may mechanically lock and unlock the second reduction gear 44. In this case, the motor center plane MC may be offset toward the first portion C1 of the casing 60 with respect to the inverter center plane IvC. [Explanation of symbols]

[0054] 10: Vehicle, 14L, 15L: Left wheel, 14R, 15R: Right wheel, 16L: First drive shaft, 16R: Second drive shaft, 16aL: First drive shaft inboard, 16aR: Second drive shaft inboard, 18: Battery, 20: Drive unit, 20g: Center of gravity, 22: First motor, 24: First reduction gear, 26: Locking mechanism, 26g: Locking gear, 26p: Locking pole, 28: Rotating shaft, 30: First inverter, 31u, 31v, 31w: First conductive path, 32: First terminal block, 34: First section, 35: Relay section, 36: Second section, 42: Second motor, 44: Second reduction gear, 48: Rotating shaft, 50: Second inverter, 51u, 51v, 51w: Second conductive path, 52: Second terminal block, 54: First section, 55: Relay section, 56: Second section, 60: Casing, 61c: First bulkhead, 61d: Second bulkhead, 61e: Third bulkhead, 62: First oil pan, 64: Second oil pan, C1: First section, C2: Second section, IbC: Inboard center plane, IvC: Inverter center plane, IR1: First inverter chamber, IR2: Second inverter chamber, MC: Motor center plane, MR1: First motor chamber, MR2: Second motor chamber, OC: Oil pan center plane, P1: Locked position, P2: Unlocked position, VC: Vehicle center plane

Claims

1. A vehicle drive unit that independently drives a pair of left and right wheels, A first motor drives one of the pair of left and right wheels, A first reduction gear for reducing the rotation of the first motor, A first inverter electrically connected to the first motor, A second motor drives the other of the pair of left and right wheels, A second reduction gear for reducing the rotation of the second motor, A second inverter electrically connected to the second motor, A locking mechanism for mechanically locking and unlocking the first reduction gear, A casing housing the first motor, the first reduction gear, the first inverter, the second motor, the second reduction gear, the second inverter, and the locking mechanism, Equipped with, The casing has a first portion that is positioned on one side of the pair of left and right wheels when the drive unit is mounted on the vehicle, and a second portion that is positioned on the other side of the pair of left and right wheels. The first motor, the first reduction gear, the first inverter, and the locking mechanism are arranged in the first portion of the casing. The second motor, the second reduction gear, and the second inverter are arranged in the second part of the casing. The motor center plane that equally divides the space between the first motor and the second motor is offset to the second portion side of the casing with respect to the inverter center plane that equally divides the space between the first inverter and the second inverter. Drive unit.

2. The casing has a first oil pan provided at the lower part of the first portion and a second oil pan provided at the lower part of the second portion. The drive unit according to claim 1, wherein the oil pan center surface that equally divides the space between the first oil pan and the second oil pan is offset with respect to the motor center surface towards the first portion of the casing.

3. The drive unit is connected to a first drive shaft connected to one of the pair of left and right wheels, and a second drive shaft connected to the other of the pair of left and right wheels. The drive unit according to claim 1, wherein the center of gravity of the drive unit is located on the inboard center plane that equally divides the space between the first drive shaft inboard of the first drive shaft and the second drive shaft inboard of the second drive shaft.

4. The aforementioned drive unit is A first terminal block fixed to the casing, A first conductive path electrically connects the first inverter and the first motor via the first terminal block, A second terminal block fixed to the casing, The system further comprises a second conductive path that electrically connects the second inverter and the second motor via the second terminal block, The total length of the first conductive path and the total length of the second conductive path are different from each other. The drive unit according to claim 1, wherein the length of the section of the first conductive path from the first motor to the first terminal block and the length of the section of the second conductive path from the second motor to the second terminal block are equal to each other.

5. The drive unit according to any one of claims 1 to 4, wherein the first motor and the second motor are arranged symmetrically with respect to the motor center plane.

6. The drive unit according to any one of claims 1 to 4, wherein the first inverter and the second inverter are arranged symmetrically with respect to the inverter's central plane.

7. The aforementioned casing is A first motor chamber located in the first part and housing the first motor and the first reduction gear, A second motor chamber located in the second part and housing the second motor and the second reduction gear, The drive unit according to any one of claims 1 to 4, further comprising a motor chamber partition wall located on the motor center plane and at least partially separating the first motor chamber and the second motor chamber.

8. The aforementioned casing is A first inverter chamber located in the first part and housing the first inverter, A second inverter chamber located in the second part and housing the second inverter, The drive unit according to claim 7, further comprising an inverter chamber partition wall located on the central plane of the inverter and at least partially separating the first inverter chamber and the second inverter chamber.

9. The drive unit according to claim 1 or 2, wherein the locking mechanism is provided on a rotating shaft connecting the first motor and the first reduction gear.

10. The locking mechanism is A locking gear fixed to the aforementioned rotating shaft, The drive unit according to claim 9, comprising a locking pawl that is movable between a locked position in which it engages with the locking gear and an unlocked position in which it is disengaged from the locking gear.

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