Vehicle electric drive unit

Abstract

The present invention provides an electric drive unit for vehicles that can incorporate a power transmission switching mechanism while avoiding an increase in size. [Solution] The electric drive unit 1 for the vehicle transmits the rotation of the rotor shaft 4 of the electric motor 3 to the left and right output shafts 11 and 12 via a reduction mechanism 5 and a differential device 7. The reduction mechanism 5 includes a counter shaft 51 arranged parallel to the rotor shaft 4, and a plurality of reduction gears 52 including a large-diameter gear 52 and a small-diameter gear 52S provided on the counter shaft 51. The differential device 7 includes a differential case 71 and a ring gear 70 arranged on the outer circumference of the differential case 71 and meshing with the reduction gears 52. The electric drive unit 1 for the vehicle further includes a power transmission switching mechanism 9 arranged between the large-diameter gear 52 and the small-diameter gear 52S in the axial direction of the counter shaft 51, which switches between a state of interrupting power transmission between the electric motor 3 and the output shafts 11 and 12 and a state of connecting power transmission.

Description

[Technical Field]

[0001] The present invention relates to an electric drive unit for a vehicle that is mounted on a vehicle using an electric motor as a drive source. [Background Art]

[0002] In recent years, efforts to realize a low-carbon or decarbonized society have become active, and research and development on electrification technology have been carried out for vehicles as well, in order to reduce CO₂ emissions and improve energy efficiency.

[0003] For example, Patent Document 1 describes a vehicle drive device that includes an electric motor, a planetary gear reducer, and a differential mechanism, and transmits the driving force of the electric motor to left and right axles via the differential mechanism. The drive device of Patent Document 1 is provided with a braking means between the ring gear of the planetary gear reducer and the housing of the drive device, which engages the ring gear and the housing and applies a braking force to the ring gear. This braking means enables switching between a state where the driving force of the electric motor is transmitted to the axles and a state where the rotational force of the axles is not transmitted to the electric motor.

[0004] Patent Document 2 describes an electric drive unit for a vehicle that transmits the rotation of a rotor shaft of an electric motor to left and right output shafts via a speed reduction mechanism and a differential device. The speed reduction mechanism in Patent Document 2 is configured as a twin counter structure including a pair of counter shafts arranged parallel to the rotor shaft, and a plurality of reduction gears of different large and small diameters respectively provided on each counter shaft. With this twin counter structure, the advantages of both the planetary structure and the parallel shaft structure are extracted to reduce the width and height dimensions, thereby achieving size reduction of the electric drive unit for a vehicle. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-264647 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2019-173833 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] When providing a mechanism for switching the connection and disconnection of power transmission in an electric drive unit for vehicles equipped with a counter shaft parallel to the rotor shaft, as described in Patent Document 2, there was room for consideration of a structure that avoids increasing the size.

[0007] The present invention provides an electric drive unit for vehicles that can incorporate a power transmission switching mechanism while avoiding an increase in size. [Means for solving the problem]

[0008] The present invention Electric motor and, A reduction mechanism, A vehicle electric drive unit comprising a differential device, which transmits the rotation of the rotor shaft of the electric motor to the left and right output shafts via the reduction mechanism and the differential device, The aforementioned reduction mechanism is A counter shaft arranged parallel to the rotor shaft, The counter shaft includes a plurality of reduction gears, including first gears and second gears of different diameters, The differential device includes a differential case and a gear disposed on the outer circumference of the differential case and meshing with the reduction gear. The aforementioned electric drive unit for the vehicle is: The system further includes a power transmission switching mechanism positioned between the first gear and the second gear in the axial direction of the counter shaft, which switches between a state of interrupting power transmission between the electric motor and the output shaft and a state of connecting power transmission. [Effects of the Invention]

[0009] According to the present invention, a power transmission switching mechanism can be provided in an electric drive unit for a vehicle while avoiding an increase in size. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view of an electric drive unit for a vehicle according to one embodiment of the present invention. [Figure 2] Figure 2 is an enlarged cross-sectional view of the vicinity of the differential device and the power transmission switching mechanism. [Figure 3] Figure 3 is a perspective view of the power transmission switching mechanism. [Figure 4] Figure 4 is a perspective view of the vehicle's electric drive unit as seen from the first end. [Figure 5] Figure 5 shows a schematic arrangement of the power transmission switching mechanism and oil tank as viewed from the axial direction of the counter shaft. [Modes for carrying out the invention]

[0011] Hereinafter, one embodiment of the electric drive unit for vehicles of the present invention will be described based on the attached drawings. The drawings should be viewed in the direction of the reference numerals.

[0012] An electric drive unit 1 for a vehicle (hereinafter also simply referred to as electric drive unit 1) according to one embodiment of the present invention is mounted on an electric vehicle. The electric vehicle is a battery electric vehicle, a hybrid vehicle including a plug-in hybrid vehicle, a fuel cell vehicle, etc. The electric drive unit 1 may be used for front-wheel drive or for rear-wheel drive. Furthermore, if the electric vehicle is all-wheel drive, the electric drive unit 1 for the vehicle may drive the main drive wheels that are responsible for relatively large torque, or it may drive the secondary drive wheels that are responsible for relatively small torque.

[0013] As shown in Figure 1, the electric drive unit 1 comprises an electric motor 3, a reduction mechanism 5, a differential device 7, a power transmission switching mechanism 9, and a unit case 2 that houses these components. Left and right output shafts 11 and 12 are connected to the electric drive unit 1. In the following description, the left end of the output shafts 11 and 12 in the axial direction (left-right direction in Figure 1) will be referred to as the first end, and the right end will be referred to as the second end. Output shaft 11 is located on the first end, and output shaft 12 is located on the second end.

[0014] (Unit Case) The unit case 2 includes a bottomed cylindrical motor case 21 and a gear case 22. The electric motor 3 is accommodated in the motor case 21, and the speed reduction mechanism 5, the differential device 7, and the power transmission switching mechanism 9 are accommodated in the gear case 22. The unit case 2 is provided with a shaft insertion portion 2a through which an output shaft 11 is inserted at an end portion on a first end side, and is provided with a shaft insertion portion 2b through which an output shaft 12 is inserted at an end portion on a second end side.

[0015] The motor case 21 is arranged on the second end side in the axial direction, and the gear case 22 is arranged on the first end side in the axial direction. That is, in the unit case 2, the speed reduction mechanism 5, the differential device 7, and the power transmission switching mechanism 9 are arranged on the first end side, and the electric motor 3 is arranged on the second end side.

[0016] (Electric Motor) The electric motor 3 is constituted by, for example, a three-phase brushless motor, and includes a hollow rotor 31 and a ring-shaped stator 32. The rotor 31 is rotatably accommodated in the motor case 21. A plurality of permanent magnets are built into the rotor 31. The stator 32 is arranged around the rotor 31 and fixed to an inner circumference of the motor case 21. Coils for three phases are wound around the stator 32.

[0017] A cylindrical rotor shaft 4 is inserted through and fixedly attached to an axial center of the rotor 31. The rotor shaft 4 rotates integrally with the rotor 31. Both axial end portions of the rotor shaft 4 are rotatably supported on the motor case 21 by bearings 41 and 42. The bearings 41 and 42 are, for example, ball bearings. A pinion gear 44 is provided on the rotor shaft 4 on the first end side in the axial direction.

[0018] The output shaft 12 is coaxially and rotatably inserted inside the rotor shaft 4. The output shaft 12 is rotatably supported by a bearing 13 at its second end in the motor case 21. The output shaft 12 extends to the outside of the motor case 21, and an axle (not shown) is connected to it via a coupling 14. Similarly, the output shaft 11 extends to the outside of the gear case 22, and an axle is connected to it via a coupling 15. Drive wheels are attached to each end of the left and right axles, respectively.

[0019] (Deceleration mechanism) The reduction mechanism 5 includes a pair of counter shafts 51 arranged parallel to the rotor shaft 4 and output shafts 11 and 12 within the gear case 22, and a plurality of reduction gears 52 of different diameters, each formed integrally on each counter shaft 51, thus constituting a twin counter structure. The reduction gears 52 include a large-diameter gear 52L and a small-diameter gear 52S that is smaller in diameter than the large-diameter gear 52L.

[0020] Each counter shaft 51 is rotatably supported in the unit case 2 by a bearing 55 at its first end and by a bearing 56 at its second end. The bearings 55 and 56 are, for example, ball bearings.

[0021] The large-diameter gear 52L is formed on the second end side of each counter shaft 51, and the small-diameter gear 52S is formed on the first end side of each counter shaft 51. The large-diameter gear 52L meshes with the pinion gear 44 provided on the rotor shaft 4. The pinion gear 44 and the large-diameter gear 52L constitute the first stage of the reduction gear train. The small-diameter gear 52S meshes with the ring gear 70 of the differential device 7, which will be described later. The small-diameter gear 52S and the ring gear 70 constitute the second stage of the reduction gear train.

[0022] In this embodiment, the pinion gear 44, the large-diameter gear 52L, the small-diameter gear 52S, and the ring gear 70 are helical gears, and axial loads are applied to the countershaft 51, the differential case 71, and the output shafts 11 and 12.

[0023] Thus, the electric drive unit 1 employs a twin counter structure in which a pair of counter shafts 51 are arranged on the reduction mechanism 5. In the twin counter structure, the radial loads applied to the differential device 7 from each counter shaft 51 are 180 degrees opposite to each other and are therefore canceled out. Furthermore, the twin counter structure combines the advantages of both the planetary structure, in which the planetary gear mechanism and differential device are arranged coaxially, and the parallel shaft structure, in which multiple reduction gears of different sizes are provided on a single counter shaft parallel to the rotor shaft, thereby reducing the axial and height dimensions. As a result, the electric drive unit 1 can be made more compact.

[0024] (Differential device) The differential device 7 is positioned between a pair of counter shafts 51 so as to be coaxial with the rotor shaft 4 and the output shafts 11 and 12.

[0025] As shown in Figure 2, the differential device 7 includes a ring gear 70, a differential case 71 rotatable around the axis centers of the output shafts 11 and 12, a pinion shaft 72 arranged perpendicular to the axis centers of the output shafts 11 and 12, a pair of pinion gears (bevel gears) 73 rotatably supported by the pinion shaft 72, a pair of side gears 74 meshing with the pair of pinion gears 73 and rotatably supported around the axis centers of the output shafts 11 and 12, and a pinion shaft support portion 75 arranged on the inner circumference side of the differential case 71 and supporting both ends of the pinion shaft 72.

[0026] The ring gear 70 is positioned on the outer circumference of the differential case 71 and meshes with the small-diameter gear 52S. Spline engagement portions 70c and 71c are formed on the inner circumference of the ring gear 70 and the outer circumference of the differential case 71, respectively, and the ring gear 70 and the differential case 71 are spline-coupled. In other words, the ring gear 70 and the differential case 71 rotate as a single unit.

[0027] The differential case 71 houses the pinion shaft 72, a pair of pinion gears 73, a pair of side gears 74, and a pinion shaft support portion 75.

[0028] The differential case 71 has a shaft insertion portion 71a provided on the first end side of the pinion shaft 72 through which the output shaft 11 is inserted, and a shaft insertion portion 71b provided on the second end side of the pinion shaft 72 through which the output shaft 12 is inserted. A bearing 81 is provided between the shaft insertion portion 71a of the differential case 71 and the shaft insertion portion 2a of the unit case 2 (gear case 22). The differential case 71 is supported by the unit case 2 so as to be rotatable relative to the bearing 81. A bearing 82 is provided between the shaft insertion portion 71b of the differential case 71 and the rotor shaft 4. The bearings 81 and 82 are, for example, ball bearings.

[0029] The output shafts 11 and 12 are fitted and connected to the pair of side gears 74, respectively, by spline coupling.

[0030] The pinion shaft support portion 75 has a ring shape with its axial direction being the same as the axial direction of the output shafts 11 and 12, and supports the pinion shaft 72. The pinion shaft support portion 75 is provided so as to be engageable with the power transmission switching mechanism 9. When the pinion shaft support portion 75 is engaged with the power transmission switching mechanism 9, a power transmission path is connected between the differential case 71 and the pinion shaft support portion 75, and the pinion shaft support portion 75 rotates integrally with the differential case 71. On the other hand, when the pinion shaft support portion 75 is disengaged from the power transmission switching mechanism 9, the power transmission path is interrupted between the differential case 71 and the pinion shaft support portion 75, and the pinion shaft support portion 75 does not rotate integrally with the differential case 71. Details regarding the connected and disengaged states of the power transmission switching mechanism 9 will be described later.

[0031] When the electric motor 3 is driven, the rotor 31 rotates together with the rotor shaft 4. The rotation of the rotor shaft 4 is reduced by the pinion gear 44 and large-diameter gear 52L of the rotor shaft 4, which constitute the first-stage reduction gear group, and transmitted to each counter shaft 51. Each counter shaft 51 rotates at a predetermined speed. The rotation of each counter shaft 51 is reduced by the small-diameter gear 52S and ring gear 70, which constitute the second-stage reduction gear group, and transmitted to the differential case 71. The differential case 71 rotates at a predetermined speed. When the power transmission switching mechanism 9 is connected, the rotation of the differential case 71 is distributed and transmitted to the output shafts 11 and 12.

[0032] When the electric vehicle is moving in a straight line, the resistance that the left and right drive wheels receive from the road surface is equal, so the pair of pinion gears 73 revolve together with the differential case 71 but do not rotate on their own. When the electric vehicle is turning, a difference occurs in the resistance that the left and right drive wheels receive from the road surface, so the pair of pinion gears 73 rotate on their own, and rotational power is distributed and transmitted to the output shafts 11 and 12 so that the rotational speed of one side gear 74 is faster than the rotational speed of the other side gear 74.

[0033] As shown in Figure 2, when the electric motor 3 outputs torque in the acceleration direction, an axial load Ka (thick solid arrow) is applied to the differential device 7 in the direction of the first end. Conversely, when the electric motor 3 outputs torque in the deceleration direction, an axial load Ka (thick dashed arrow) is applied to the differential device 7 in the direction of the second end. Note that each counter shaft 51 is subjected to an axial load Ka in the direction of the second end during acceleration, and an axial load Ka in the direction of the first end during deceleration.

[0034] The bearing 81 provided on the first end side of the differential case 71 is configured to support both an axial load Ka in the direction toward the first end and an axial load Ka in the direction toward the second end in the axial direction.

[0035] To specifically describe the support of the axial load Ka by the bearing 81, the electric drive unit 1 further includes an outer restraint portion 83 positioned adjacent to the bearing 81 and the unit case 2, and an inner restraint portion 84 positioned adjacent to the bearing 81 and the differential case 71. The outer restraint portion 83 and the inner restraint portion 84 are, for example, circlips. Both the outer restraint portion 83 and the inner restraint portion 84 are positioned on the first end side with respect to the bearing 81.

[0036] During the assembly of the electric drive unit 1, the bearing 81 is inserted into the inner circumference of the shaft insertion portion 2a of the unit case 2 from the first end side and abuts against the contact portion 27 formed in the shaft insertion portion 2a. After the bearing 81 is inserted, the outer restraint portion 83 is fitted into the inner circumference of the shaft insertion portion 2a from the first end side and engages with the groove 28 formed in the shaft insertion portion 2a. Subsequently, the shaft insertion portion 71a of the differential case 71 is inserted into the inner circumference of the bearing 81 from the second end side. The bearing 81 abuts against the contact portion 77 formed in the shaft insertion portion 71a. The inner restraint portion 84 is fitted into the outer circumference of the shaft insertion portion 71a from the first end side and engages with the groove 78 formed in the shaft insertion portion 71a. In this way, the bearing 81 is fitted between the differential case 71 and the unit case 2.

[0037] The bearing 81 is prevented from moving relative to the gear case 22 in the axial direction by the outer restraint portion 83, and its relative movement relative to the differential case 71 in the axial direction by the inner restraint portion 84. Therefore, when the electric motor 3 outputs torque in the acceleration direction, the bearing 81 can receive an axial load Ka in the direction toward the first end via the outer restraint portion 83. Also, when the electric motor 3 outputs torque in the deceleration direction, the bearing 81 can receive an axial load Ka in the direction toward the second end via the inner restraint portion 84.

[0038] The bearing 82, located on the second end side of the differential case 71, is positioned on the inner circumference side of the shaft insertion portion 71b of the differential case 71. The bearing 82 is positioned between the shaft insertion portion 71b of the differential case 71 and the rotor shaft 4.

[0039] Thus, the differential case 71 is a cantilevered support structure supported by the unit case 2 at its first end (shaft insertion portion 71a), and the axial load in both directions in the axial direction is received only by the bearing 81 at the first end. With this configuration, there is no need to provide a member to support the bearing 82 at the second end relative to the unit case 2, and the axial dimension can be shortened. As a result, the electric drive unit 1 can be made smaller.

[0040] Furthermore, in a structure where the differential case 71 is positioned on the first end side of the unit case 2, the bearing 81, which receives axial loads in both directions, is positioned between the first end side of the unit case 2 (shaft insertion portion 2a) and the first end side of the differential case 71 (shaft insertion portion 71a). Therefore, compared to the case where the bearing 81, which receives axial loads in both directions, is positioned on the second end side of the differential case 71, the structure for supporting the bearing 81 in the unit case 2 can be simplified. As a result, the electric drive unit 1 can be made smaller.

[0041] Furthermore, although the differential case 71 has a cantilever support structure supported by the unit case 2 at its first end, its second end is supported by the rotor shaft 4 by the bearing 82, thus maintaining the rotation axis of the differential case 71.

[0042] The ring gear 70 is positioned to be movable relative to the differential case 71. Specifically, the ring gear 70 and the differential case 71 are not fastened to each other with fastening members (e.g., bolts), but are spline-coupled with some play. This configuration allows for a self-aligning function at the meshing portion between the reduction mechanism 5 and the differential device 7. In contrast, if the ring gear were fixed to the differential case in a cantilevered differential case, making relative movement impossible, a high degree of precision would be required in the connection between the differential case and the ring gear.

[0043] In this embodiment, the ring gear 70 is positioned to be radially movable relative to the differential case 71, but not axially movable. Regarding the restriction of axial movement, for example, a restraining portion 76 is provided between the ring gear 70 and the differential case 71 to restrain their relative axial movement. The restraining portion 76 is, for example, a circlip. In this way, since the ring gear 70 is positioned not to be axially movable relative to the differential case 71, the axial load generated by meshing with the small-diameter gear 52S can be transmitted to the bearing 81.

[0044] (Power transmission switching mechanism) The power transmission switching mechanism 9 switches the connection and disconnection of power transmission between the electric motor 3 and the output shafts 11 and 12. The state in which power can be transmitted between the electric motor 3 and the output shafts 11 and 12 is called the connected state, and the state in which power cannot be transmitted is called the disconnected state.

[0045] The details of the power transmission switching mechanism 9 will be explained with reference to Figures 2 and 3. Note that in Figure 3, a portion of the ring gear 70 and the differential case 71 are omitted from the illustration in order to show the structure of the power transmission switching mechanism 9.

[0046] The power transmission switching mechanism 9 includes a base 91 fixed to the unit case 2, an engaging portion 92 that can engage with the pinion shaft support portion 75 of the differential device 7, an operating portion 93 for operating the engaging portion 92, and an actuator 94 for operating the operating portion 93. The base 91 supports the operating portion 93 and the actuator 94.

[0047] The engaging portion 92 is positioned on the outer circumference of the second end side (shaft insertion portion 71b) of the differential case 71 and rotates integrally with the differential case 71. The engaging portion 92 has a gear portion 92g that can mesh with a gear portion 75g formed on the pinion shaft support portion 75. The gear portion 75g and the gear portion 92g are formed to face each other in the axial direction. The engaging portion 92 is provided so as to be movable in the axial direction by the operation of the operating portion 93.

[0048] The operating part 93 is, for example, a shift fork. The operating part 93 is supported on the base 91 so as to be rotatable around the shaft portion 93a, and rotates around the shaft portion 93a by the drive of the actuator 94. The operating part 93 contacts the engaging portion 92 and moves the engaging portion 92 in the axial direction.

[0049] The actuator 94 rotates the operating section 93 around the shaft 93a, as shown by the white arrow in Figure 3. Various types of actuators can be used for the actuator 94, such as a solenoid type actuator that is driven by generating a magnetic field around a coil, or an actuator using a motor and a ball screw.

[0050] When the engaging portion 92 is operated by the operating portion 93 in a direction that moves it closer to the pinion shaft support portion 75, the gear portion 92g meshes with the gear portion 75g, and the power transmission switching mechanism 9 becomes connected. At this time, a power transmission path is connected between the differential case 71 and the pinion shaft support portion 75, and the pinion shaft support portion 75 rotates integrally with the differential case 71 via the engaging portion 92. In other words, power can be transmitted between the electric motor 3 and the output shafts 11 and 12.

[0051] On the other hand, when the engaging portion 92 is operated away from the pinion shaft support portion 75 by the operation of the operating portion 93, the gear portion 92g separates from the gear portion 75g, and the power transmission switching mechanism 9 is disengaged. At this time, the power transmission path between the differential case 71 and the pinion shaft support portion 75 is interrupted, and the pinion shaft support portion 75 does not rotate integrally with the differential case 71. In other words, power cannot be transmitted between the electric motor 3 and the output shafts 11 and 12.

[0052] For example, when the electric drive unit 1 is used as a secondary drive unit to drive the secondary drive wheels, the running resistance can be reduced when the electric drive unit 1 is not being driven by disengaging the power transmission switching mechanism 9.

[0053] As shown in Figure 2, the power transmission switching mechanism 9 (specifically the operating unit 93) is positioned between the large-diameter gear 52L and the small-diameter gear 52S in the axial direction of the counter shaft 51. By effectively utilizing the space between the large-diameter gear 52L and the small-diameter gear 52S in the axial direction, the space efficiency within the electric drive unit 1 can be improved. Therefore, even when the power transmission switching mechanism 9 is provided, it is possible to avoid increasing the size of the electric drive unit 1.

[0054] Next, the arrangement of the components of the electric drive unit 1 as viewed from the axial direction will be explained with reference to Figures 4 and 5.

[0055] The pair of counter shafts 51 are arranged diagonally above and below the output shafts 11 and 12 in a point-symmetrical manner. That is, the pair of counter shafts 51 and the output shafts 11 and 12 are arranged on the same plane P that intersects with the horizontal direction. This arrangement of the counter shafts 51 makes it possible to reduce the axial length and vertical height of the electric drive unit 1.

[0056] The electric drive unit 1 further includes an oil tank 17 for storing cooling and / or lubricating oil. The oil tank 17 is positioned so as not to overlap with the pair of counter shafts 51 in an axial view of the counter shafts 51. Specifically, as shown in Figure 5, the oil tank 17 is positioned in an upper region A1 that is vertically above the plane P, that is, above the lower of the pair of counter shafts 51.

[0057] Oil accumulates at the bottom of the unit case 2, and the large-diameter gear 52L, located on the lower counter shaft 51, rotates, scooping up the oil. A portion of the scooped-up oil is introduced into the oil tank 17 through an inlet 17a formed in the oil tank 17 and stored there. The oil stored in the oil tank 17 drips down toward the bearing 55 through an outlet 17b formed on the bottom surface of the oil tank 17. The remaining oil flies toward the counter shaft 51 on the opposite side.

[0058] Since the electric drive unit 1 is equipped with an oil tank 17, the amount of oil stored at the bottom of the unit case 2 can be reduced. As a result, the oil level can be lowered, reducing the oil stirring resistance caused by the large-diameter gear 52L and thus reducing power loss. Furthermore, since the oil tank 17 is positioned so as not to overlap with the pair of counter shafts 51 in an axial view, the space efficiency of the unit case 2 can be improved. Therefore, even when an oil tank 17 is provided, it is possible to avoid increasing the size of the electric drive unit 1.

[0059] The base 91 and actuator 94 of the power transmission switching mechanism 9 are positioned so as not to overlap with the pair of counter shafts 51 in an axial view of the counter shaft 51. Specifically, the base 91 and actuator 94 are positioned in the lower region A2, which is vertically below the plane P, that is, below the upper counter shaft 51 of the pair of counter shafts 51. This arrangement improves space efficiency within the unit case 2. Therefore, even when the power transmission switching mechanism 9 is provided, it is possible to avoid increasing the size of the electric drive unit 1.

[0060] With this arrangement of the actuator 94, the actuator 94 is positioned near the oil accumulated at the bottom of the unit case 2. Therefore, the operating noise of the actuator 94 can be reduced.

[0061] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to this embodiment. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these are also understood to naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiment may be combined in any way without departing from the spirit of the invention.

[0062] For example, in the embodiment described above, the base 91 and actuator 94 of the power transmission switching mechanism 9 are arranged in the lower region A2, but if, for example, the oil tank 17 is not provided, the base 91 and actuator 94 may be arranged in the upper region A1.

[0063] This specification includes at least the following: The components and other elements corresponding to those in the embodiments described above are shown in parentheses as examples, but are not limited thereto.

[0064] (1) Electric motor (electric motor 3), The reduction mechanism (reduction mechanism 5), A vehicle electric drive unit (vehicle electric drive unit 1) comprising a differential device (differential device 7), which transmits the rotation of the rotor shaft (rotor shaft 4) of the electric motor to the left and right output shafts (output shafts 11, 12) via the reduction mechanism and the differential device, The aforementioned reduction mechanism is A counter shaft (counter shaft 51) is arranged parallel to the rotor shaft, The counter shaft includes a plurality of reduction gears (reduction gears 52) including a first gear (large diameter gear 52L) and a second gear (small diameter gear 52S) of different diameters, The differential device includes a differential case (differential case 71) and a gear (ring gear 70) arranged on the outer circumference of the differential case and meshing with the reduction gear. The aforementioned electric drive unit for the vehicle is: The counter shaft further comprises a power transmission switching mechanism (power transmission switching mechanism 9) positioned between the first gear and the second gear in the axial direction of the counter shaft, which switches between a state of interrupting power transmission between the electric motor and the output shaft and a state of connecting power transmission. Electric drive unit for vehicles.

[0065] According to (1), by placing a power transmission switching mechanism in the space between the first gear and the second gear, which have different diameters, and effectively utilizing that space, the space efficiency within the electric drive unit can be improved. Therefore, even when a power transmission switching mechanism is provided, it is possible to avoid increasing the size of the electric drive unit.

[0066] (2) The electric drive unit for vehicles described in (1), The counter shafts are a pair of counter shafts arranged parallel to the rotor shafts, The power transmission switching mechanism includes an actuator (actuator 94) that switches the state of power transmission. The actuator is positioned so as not to overlap with the pair of counter axes in an axial view of the counter axis. Electric drive unit for vehicles.

[0067] According to (2), the actuator is positioned so as not to overlap with the pair of counter axes in an axial view, thereby further improving space efficiency within the electric drive unit and avoiding an increase in the size of the electric drive unit.

[0068] (3) The electric drive unit for vehicles described in (2), The rotor shaft and the pair of counter shafts are arranged on the same plane (plane P), The aforementioned plane is a plane that intersects the horizontal direction, The actuator is positioned vertically below the plane. Electric drive unit for vehicles.

[0069] According to (3), the actuator is positioned below the pair of counter axes in an axial view, thereby improving space efficiency within the electric drive unit and avoiding an increase in the size of the electric drive unit.

[0070] (4) The electric drive unit for vehicles described in (3), The unit further comprises a unit case (unit case 2) housing the electric motor, the reduction mechanism, the differential device, and the power transmission switching mechanism. The unit case contains a liquid for cooling and / or lubrication. Electric drive unit for vehicles.

[0071] According to (4), the actuator is placed near the liquid, which reduces the operating noise of the actuator. [Explanation of symbols]

[0072] 1. Electric drive unit for vehicles 2 Unit Case 3 Electric motor 4 rotor shafts 5 Reduction mechanism 7 Differential device 9. Power transmission switching mechanism 11 Output shaft 12 Output shafts 51 Counter axis 52 Reduction gear 52L Large diameter gear (1st gear) 52S Small diameter gear (2nd gear) 70 Ring gear (gear) 71 Differential Case 94 Actuators

Claims

1. Electric motor and, A reduction mechanism, A vehicle electric drive unit comprising a differential device, which transmits the rotation of the rotor shaft of the electric motor to the left and right output shafts via the reduction mechanism and the differential device, The aforementioned reduction mechanism is A counter shaft arranged parallel to the rotor shaft, The counter shaft includes a plurality of reduction gears, including first gears and second gears of different diameters, The differential device includes a differential case and a gear disposed on the outer circumference of the differential case and meshing with the reduction gear. The aforementioned electric drive unit for the vehicle is: The counter shaft is further provided with a power transmission switching mechanism positioned between the first gear and the second gear in the axial direction of the counter shaft, which switches between a state of interrupting power transmission between the electric motor and the output shaft and a state of connecting power transmission. Electric drive unit for vehicles.

2. An electric drive unit for a vehicle according to claim 1, The counter shafts are a pair of counter shafts arranged parallel to the rotor shafts, The power transmission switching mechanism includes an actuator that switches the state of power transmission. The actuator is positioned so as not to overlap with the pair of counter axes in an axial view of the counter axis. Electric drive unit for vehicles.

3. The electric drive unit for a vehicle according to claim 2, The rotor shaft and the pair of counter shafts are arranged on the same plane. The aforementioned plane is a plane that intersects the horizontal direction, The actuator is positioned vertically below the plane. Electric drive unit for vehicles.

4. The electric drive unit for a vehicle according to claim 3, The unit case further comprises the electric motor, the reduction mechanism, the differential device, and the power transmission switching mechanism, The unit case contains a liquid for cooling and / or lubrication. Electric drive unit for vehicles.

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