Vehicle drive device

Abstract

To realize a vehicle drive device capable of reducing vibration of a rotor shaft and an input shaft.SOLUTION: A vehicle drive device comprises: a rotating electric machine 1 provided with a rotor 12; a rotor shaft 2 fixed to the rotor 12 so as to integrally rotate with the rotor 12; an input shaft 3 which is arranged coaxially with the rotor shaft 2 and provided with a first gear; an output member which is connected to wheels in a drivable manner; a power transmission mechanism; and a case 9. The rotor 12 and the first gear are arranged at different positions along an axial direction L. The rotor shaft 2 and the input shaft 3 are connected to each other through a spline engagement section 8 engaging with a radial direction fitting section 6, which fits in a radial direction R, in a circumferential direction so as to integrally rotate. The rotor shaft 2 and the input shaft 3 are rotatably supported with respect to the case 9 at three locations along the axial direction L by a first bearing, a second bearing and a third bearing B3. The third bearing B3 is arranged at a position between the rotor 12 and the first gear along the axial direction L and overlapping with the radial direction fitting section 6 when viewed in the radial direction R.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle drive device comprising: a rotating electric machine having a rotor; a rotor shaft fixed to the rotor so as to rotate integrally with the rotor; an input shaft arranged coaxially with the rotor shaft and having a first gear; an output member drivingly connected to wheels; a power transmission mechanism having a second gear meshing with the first gear and drivingly connecting the second gear to the output member; and a case that houses the rotating electric machine, the rotor shaft, the input shaft, and the power transmission mechanism. [Background technology]

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

[0003] In the vehicle drive device (14) of Patent Document 1, a rotor shaft (26) connected to a rotor (12b) of a rotating electric machine (12) so as to rotate integrally therewith is formed in a cylindrical shape. An end of an input shaft (22a) is disposed radially inside the rotor shaft (26), and the shafts are connected to each other by spline engagement so as to rotate integrally. Such rotor shaft (26) and input shaft (22a) are disposed in a space in the case (18) that accommodates the rotating electric machine (12), the counter gear mechanism (22), and the like. The rotor shaft (26) is rotatably supported relative to the case (18) via a pair of rotor bearings (28a, 28b) arranged separately in the axial direction (left and right direction in FIG. 1 of Patent Document 1). The input shaft (22a) is rotatably supported relative to the case (18) via a pair of input bearings (32a, 32b) arranged separately in the axial direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-129608 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described configuration in which the rotor shaft and the input shaft are connected to each other by spline engagement and each shaft is supported by a case via a different bearing, different loads act on each shaft, such as the rotor shaft being subjected to centrifugal force due to the rotation of the rotor and the input shaft being subjected to gear meshing reaction force, etc., and therefore the rotor shaft and the input shaft are likely to be in different vibration states. As a result, the rotational axis of the rotor shaft and the rotational axis of the input shaft are likely to be misaligned, and the misalignment of the rotational axes tends to cause large vibrations of each shaft.

[0006] Therefore, it is desirable to realize a vehicle drive device that can reduce vibrations in the rotor shaft and the input shaft.

[0007] A rotating electric machine having a rotor; a rotor shaft fixed to the rotor so as to rotate integrally with the rotor; an input shaft arranged coaxially with the rotor shaft and equipped with a first gear; An output member drivingly connected to the wheels; a power transmission mechanism including a second gear that meshes with the first gear and drivingly connects the first gear and the output member; a case that accommodates the rotating electric machine, the rotor shaft, the input shaft, and the power transmission mechanism, a direction along the axis of the rotor shaft is defined as an axial direction, a direction perpendicular to the axis is defined as a radial direction, a direction going around the axis is defined as a circumferential direction, a side in the axial direction where the rotor is disposed with respect to the first gear is defined as an axial first side, and a side in the axial direction opposite to the axial first side is defined as an axial second side, the rotor and the first gear are disposed at different positions in the axial direction, the rotor shaft and the input shaft are connected to each other so as to rotate integrally with each other via a radial fitting portion that fits in the radial direction and a spline engagement portion that engages in the circumferential direction, the rotor shaft and the input shaft are rotatably supported with respect to the case at three locations in the axial direction by a first bearing, a second bearing, and a third bearing, the first bearing is disposed on the first axial side with respect to the rotor, the second bearing is disposed on the second axial side with respect to the first gear, The third bearing is disposed between the rotor and the first gear in the axial direction and at a position overlapping with the radial fitting portion as viewed in the radial direction along the radial direction.

[0008] According to this configuration, the rotor shaft and the input shaft are engaged with each other via the spline engagement portion, so that the two shafts can rotate together, and the rotor shaft and the input shaft are connected with each other via the radial fitting portion, so that the misalignment of the rotational axes of the two shafts can be minimized, thereby reducing vibrations caused by the misalignment of the rotational axes of the rotor shaft and the input shaft. Furthermore, according to this configuration, the rotor shaft and the input shaft are supported by the case via the first bearing, the second bearing, and the third bearing that is located between the rotor and the first gear in the axial direction and overlaps with the radial fitting portion when viewed from the radial direction, so that it is possible to stably support both the centrifugal force caused by the rotation of the rotor and the reaction force that the first gear receives from the second gear, and therefore it is possible to reduce vibrations caused by these forces. In this manner, with this configuration, vibrations of the rotor shaft and the input shaft can be reduced.

[0009] Further features and advantages of the vehicle drive device will become apparent from the following description of the embodiments, which are given with reference to the drawings. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view taken along an axial direction of a vehicle drive device according to an embodiment; [Diagram 2] 1 is a skeleton diagram of a vehicle drive device according to an embodiment of the present invention; [Diagram 3]FIG. 2 is a partially enlarged cross-sectional view of the vehicle drive device according to the embodiment taken along an axial direction; [Figure 4] FIG. 1 is a cross-sectional view of an input shaft according to an embodiment of the present invention taken along an axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A vehicle drive device 100 according to an embodiment will be described below with reference to the drawings. As shown in Fig. 1 and Fig. 2, the vehicle drive device 100 includes a rotating electric machine 1 including a rotor 12, a rotor shaft 2, an input shaft 3 including a first gear 31, an output member 4, a power transmission mechanism 5, and a case 9.

[0012] The rotating electric machine 1 functions as a driving force source for the wheels W (see FIG. 2). The rotating electric machine 1 has a function as a motor (electric motor) that receives a supply of electric power to generate power, and a function as a generator (electric power generator) that receives a supply of power to generate electric power. Specifically, the rotating electric machine 1 is electrically connected to an electric storage device (not shown) such as a battery or a capacitor. The rotating electric machine 1 generates driving force by running using electric power stored in the electric storage device. The rotating electric machine 1 also generates power using driving force transmitted from the wheels W to charge the electric storage device.

[0013] The rotor shaft 2 is a shaft member fixed to the rotor 12 so as to rotate integrally with the rotor 12. The input shaft 3 is a shaft member connected to the rotor shaft 2 so as to rotate integrally with the rotor shaft 2. The output member 4 is drivingly connected to the wheels W. The power transmission mechanism 5 includes a second gear 511 that meshes with the first gear 31, and is configured to drivingly connect the first gear 31 and the output member 4. In this embodiment, the power transmission mechanism 5 includes a counter gear mechanism 51 and a differential gear mechanism 52.

[0014] Here, in this application, "driving connection" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force, and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as shafts, gear mechanisms, belts, chains, etc. Note that the transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices.

[0015] As shown in Figs. 1 and 2, the input shaft 3 is arranged coaxially with the rotor shaft 2. Specifically, the rotor shaft 2 and the input shaft 3 are arranged on a first axis X1 which is the rotation axis of the rotating electric machine 1 (rotor 12). The counter gear mechanism 51 is arranged on a second axis X2 different from the first axis X1. The output member 4 and the differential gear mechanism 52 are arranged on a third axis X3 different from the first axis X1 and the second axis X2. In this example, the above-mentioned axes X1 to X3 are arranged parallel to one another.

[0016] In the following description, the direction along the axis of the rotor shaft 2 is referred to as the axial direction L, the direction perpendicular to the axis of the rotor shaft 2 is referred to as the radial direction R, and the direction going around the axis of the rotor shaft 2 is referred to as the circumferential direction C. The side on which the rotor 12 is arranged with respect to the first gear 31 in the axial direction L is referred to as the first axial side L1, and the side opposite to the first axial side L1 in the axial direction L is referred to as the second axial side L2. In this embodiment, the direction parallel to the above-mentioned axes X1 to X3 is referred to as the "axial direction L" of the vehicle drive device 100. Furthermore, the direction perpendicular to the rotation axis of the rotating member such as the rotor 12 is referred to as the "radial direction R" based on each rotation axis. Note that when it is not necessary to distinguish which rotation axis is used as the reference or when it is clear which rotation axis is used as the reference, it may be simply referred to as the "radial direction R".

[0017] The case 9 accommodates the rotating electric machine 1, the rotor shaft 2, the input shaft 3, and the power transmission mechanism 5. In this embodiment, the case 9 also accommodates a pair of output members 4.

[0018] 1, in this embodiment, a first housing section A1, a second housing section A2, and a third housing section A3 are formed inside the case 9. The first housing section A1 is a space in which the rotating electric machine 1 and the rotor shaft 2 are accommodated. The second housing section A2 is a space in which the input shaft 3 and the counter gear mechanism 51 are accommodated. The third housing section A3 is a space in which the pair of output members 4 and the differential gear mechanism 52 are accommodated.

[0019] In this embodiment, the case 9 includes a partition portion 91, a first peripheral wall portion 92a, a first side wall portion 92b, a second peripheral wall portion 93a, a second side wall portion 93b, a third peripheral wall portion 94a, a third side wall portion 94b, and a fourth side wall portion 94c.

[0020] The partition wall 91 is formed to separate the first housing portion A1 and the second housing portion A2. In this embodiment, the partition wall 91 is formed inside the case 9 to separate the first housing portion A1 and the second housing portion A2 in the axial direction L.

[0021] The first peripheral wall portion 92a is formed so as to cover the outside of the rotating electric machine 1 in the radial direction R. The first side wall portion 92b is formed so as to cover the first axial side L1 of the rotating electric machine 1. In this embodiment, the first peripheral wall portion 92a is formed in a cylindrical shape with an opening on the first axial side L1. The opening on the first axial side L1 of the first peripheral wall portion 92a is closed by the first side wall portion 92b. Meanwhile, a partition portion 91 is integrally provided on a portion of the first peripheral wall portion 92a on the second axial side L2 with respect to the rotating electric machine 1.

[0022] The second peripheral wall portion 93a is formed so as to cover the outside of the input shaft 3 and the counter gear mechanism 51 in the radial direction R. The second side wall portion 93b is formed so as to cover the second axial side L2 of the input shaft 3 and the counter gear mechanism 51. In this embodiment, the second peripheral wall portion 93a is formed in a cylindrical shape with an opening on the second axial side L2. The opening on the second axial side L2 of the second peripheral wall portion 93a is closed by the second side wall portion 93b. Meanwhile, a partition portion 91 is integrally provided on a portion of the second peripheral wall portion 93a on the first axial side L1 relative to the first gear 31.

[0023] The third peripheral wall portion 94a is formed so as to cover the pair of output members 4 and the outside of the differential gear mechanism 52 in the radial direction R. The third side wall portion 94b is formed so as to cover the first axial side L1 of the differential gear mechanism 52. The fourth side wall portion 94c is formed so as to cover the second axial side L2 of the differential gear mechanism 52. In this embodiment, the third peripheral wall portion 94a is formed in a cylindrical shape with an opening on the second axial side L2. The opening on the first axial side L1 of the third peripheral wall portion 94a is closed by the third side wall portion 94b, and the opening on the second axial side L2 of the third peripheral wall portion 94a is closed by the fourth side wall portion 94c. In this example, a partition portion 91 is integrally provided on the portion of the third peripheral wall portion 94a on the first axial side L1 with respect to the differential gear mechanism 52.

[0024] In this embodiment, the first peripheral wall portion 92a is formed so as to extend from the partition wall portion 91 to the first axial side L1. The second peripheral wall portion 93a is formed so as to extend from the partition wall portion 91 to the second axial side L2. In the example shown in FIG. 1, the partition wall portion 91, the first peripheral wall portion 92a, the second peripheral wall portion 93a, and the third peripheral wall portion 94a are integrally formed to configure the first case portion 9A. The second case portion 9B including the first side wall portion 92b and the third side wall portion 94b is joined to the first case portion 9A from the first axial side L1. The third case portion 9C including the second side wall portion 93b and the fourth side wall portion 94c is joined to the first case portion 9A from the second axial side L2.

[0025] In this embodiment, the first housing section A1 is formed by the partition wall 91, the first peripheral wall 92a, and the first side wall 92b. That is, the space surrounded by the partition wall 91, the first peripheral wall 92a, and the first side wall 92b inside the case 9 is formed as the first housing section A1.

[0026] In this embodiment, the second storage section A2 is formed by the partition wall 91, the second peripheral wall 93a, and the second side wall 93b. That is, the space surrounded by the partition wall 91, the second peripheral wall 93a, and the second side wall 93b inside the case 9 is formed as the second storage section A2. In addition, the third storage section A3 is formed by the third peripheral wall 94a, the partition wall 91, and the fourth side wall 94c. That is, the space surrounded by the third peripheral wall 94a, the partition wall 91, and the fourth side wall 94c inside the case 9 is formed as the third storage section A3. In this embodiment, the second storage section A2 and the third storage section A3 are formed so as to communicate with each other.

[0027] The rotating electric machine 1 further includes a stator 11. In this embodiment, the stator 11 includes a cylindrical stator core 111. The stator core 111 is fixed to a non-rotating member. In this embodiment, the stator core 111 is fixed to a first circumferential wall portion 92a of the case 9, which serves as a non-rotating member. The rotor 12 of the rotating electric machine 1 includes a cylindrical rotor core 121. The rotor core 121 is supported rotatably relative to the stator core 111.

[0028] In this embodiment, the rotating electric machine 1 is an inner rotor type rotating electric machine. That is, the stator 11 is disposed outside the rotor 12 in the radial direction R. Therefore, the stator core 111 is disposed outside the rotor core 121 in the radial direction R.

[0029] In this embodiment, the rotating electric machine 1 is a rotating field type rotating electric machine. Therefore, a stator coil is wound around the stator core 111. The stator coil is wound around the stator core 111 so as to form a pair of coil end portions 112 that protrude toward a first axial side L1 and a second axial side L2 with respect to the stator core 111. Furthermore, the rotor core 121 is provided with a permanent magnet (not shown).

[0030] In this embodiment, the rotor shaft 2 includes a cylindrical portion 21 and a connection portion 22. The cylindrical portion 21 is formed in a cylindrical shape having an axis along the axial direction L. In this embodiment, the cylindrical portion 21 is formed in a cylindrical shape having an axis on the first axis X1. In the example shown in FIG. 1, the cylindrical portion 21 is arranged so as to protrude from the rotor 12 to each of the axial first side L1 and the axial second side L2. The connection portion 22 is formed so as to connect the cylindrical portion 21 and the input shaft 3. In this embodiment, the connection portion 22 is formed integrally with the cylindrical portion 21 so as to extend from the end of the axial second side L2 of the cylindrical portion 21 toward the inside in the radial direction R and further toward the axial second side L2. For this reason, the connection portion 22 is formed so as to have a smaller diameter than the cylindrical portion 21. In this example, the connection portion 22 of the rotor shaft 2 is connected to the coupling portion 32 of the input shaft 3, and the rotor shaft 2 and the input shaft 3 form a shaft body S (FIG. 1). Here, the connecting portion 32 is a portion including the end of the input shaft 3 on the first axial side L1 (FIG. 3). In this embodiment, the input shaft 3 is formed in a cylindrical shape. More specifically, the input shaft 3 is formed in a cylindrical shape that opens on both sides in the axial direction L. In other words, the input shaft 3 has a hollow structure as a whole. Therefore, the connecting portion 32 is also formed in a cylindrical shape that opens on both sides in the axial direction L. Note that the input shaft 3 may have a solid structure.

[0031] As shown in FIG. 1 and FIG. 3, the rotor shaft 2 and the input shaft 3 are connected to each other so as to rotate integrally with each other via a radial fitting portion 6 that fits in the radial direction R and a spline engagement portion 8 that engages in the circumferential direction C. In this embodiment, the radial fitting portion 6 and the spline engagement portion 8 are provided at an end portion of the rotor shaft 2 on the second axial side L2 (here, the connection portion 22 formed on the second axial side L2 further than the cylindrical portion 21) and an end portion of the input shaft 3 on the first axial side L1. In this example, the inner diameter of the connection portion 22 is set to a size corresponding to the outer diameter of the end portion of the input shaft 3 on the first axial side L1 (here, the connection portion 32). Here, the connection portion 22 is formed in a cylindrical shape that is open at least on the second axial side L2 (here, both the first axial side L1 and the second axial side L2). The rotor shaft 2 and the input shaft 3 are connected by inserting the connecting portion 32 of the input shaft 3 into the connecting portion 22 from the opening on the second axial side L2 of the connecting portion 22. In this manner, the radial fitting portion 6 and the spline engagement portion 8 are provided in a portion where the connecting portion 22 and the connecting portion 32 overlap when viewed in the radial direction along the radial direction R. That is, in this example, in both the radial fitting portion 6 and the spline engagement portion 8, the connecting portion 22 of the rotor shaft 2 (specifically, the wall portion of the connecting portion 22) is disposed on the outside in the radial direction R, and the connecting portion 32 of the input shaft 3 (specifically, the wall portion of the connecting portion 32) is disposed on the inside. With regard to the arrangement of two elements, "overlapping when viewed in a specific direction" means that when a virtual line parallel to the line of sight is moved in each direction perpendicular to the virtual line, there is at least a part of an area where the virtual line intersects with both of the two elements.

[0032] In this embodiment, as shown in Figs. 1 and 3, the spline engagement portion 8 is disposed on the first axial side L1 with respect to the radial fitting portion 6. In this example, in a state where the rotor shaft 2 and the input shaft 3 are connected (i.e., in a state where the connection portion 22 and the coupling portion 32 overlap when viewed in the radial direction R), the spline engagement portion 8 and the radial fitting portion 6 are disposed to be aligned with the connection portion 22 and the coupling portion 32 in the axial direction L. A portion of the connection portion 22 on the first axial side L1 from the center in the axial direction L and a portion of the coupling portion 32 on the first axial side L1 from the center of the first axial side L1 are connected by spline engagement. In this example, a plurality of recesses and protrusions along the axial direction L are alternately formed on the inner peripheral surface 2a of the connection portion 22 and the outer peripheral surface 3b of the coupling portion 32 in the spline engagement portion 8 all around the circumference in the circumferential direction C, whereby the rotor shaft 2 and the input shaft 3 are spline-engaged.

[0033] As shown in Figs. 1 and 3, the radial fitting portion 6 is a portion where the inner peripheral surface 2a of the cylindrical rotor shaft 2 and the outer peripheral surface 3b of the input shaft 3 are in contact with each other in the radial direction R. In this embodiment, the radial fitting portion 6 is a fitting portion between the connection portion 22 of the rotor shaft 2 and the coupling portion 32 of the input shaft 3 in a state where the rotor shaft 2 and the input shaft 3 are connected (hereinafter, sometimes simply referred to as a "connected state"). In the connected state, the inner peripheral surface 2a of the rotor shaft 2 (the inner peripheral surface 2a of the connection portion 22) and the outer peripheral surface 3b of the input shaft 3 (the outer peripheral surface 3b of the coupling portion 32) abut on each other over the entire circumference in the circumferential direction C. As a result, the connection portion 22 and the coupling portion 32 are in a fitted state. In this embodiment, the rotor shaft 2 and the input shaft 3 are fitted to each other in the radial fitting portion 6 by clearance fit or intermediate fit. The rotor shaft 2 and the input shaft 3 may be fitted together by an interference fit (press fit, shrink fit, or the like) at the radial fitting portion 6. In this manner, in the present embodiment, at a portion where the rotor shaft 2 and the input shaft 3 are connected (here, a portion where the coupling portion 32 is inserted into the connection portion 22), the connection portion 22 and the coupling portion 32 are connected together by spline engagement at a portion on the first axial side L1 with respect to the radial fitting portion 6, and the connection portion 22 and the coupling portion 32 are fitted together at a portion on the second axial side L2 with respect to the spline engagement portion 8, so that the rotor shaft 2 and the input shaft 3 are firmly connected together.

[0034] Furthermore, the rotor shaft 2 and the input shaft 3 are supported by a case 9 so as to rotate together about an axis along the first axis X1. As shown in Fig. 1 and Fig. 2, the rotor shaft 2 and the input shaft 3 are rotatably supported by the case 9 at three locations in the axial direction L by a first bearing B1, a second bearing B2, and a third bearing B3.

[0035] The first bearing B1 is disposed on the first axial side L1 with respect to the rotor 12. The first bearing B1 rotatably supports the rotor shaft 2 constituting the shaft body S. In this embodiment, the first bearing B1 is disposed so as to support the inner peripheral surface of the cylindrical portion 21 of the rotor shaft 2 from the inside in the radial direction R. In the example shown in FIG. 1, the first side wall portion 92b of the case 9 has a first bearing support portion 92c. The first bearing support portion 92c is formed in a cylindrical shape protruding toward the second axial side L2 so as to overlap with the cylindrical portion 21 in a radial view along the radial direction R, inside the cylindrical portion 21 in the radial direction R. The first bearing B1 is disposed between the outer peripheral surface of the first bearing support portion 92c and the inner peripheral surface of the cylindrical portion 21.

[0036] The second bearing B2 is disposed on the second axial side L2 with respect to the first gear 31. The second bearing B2 rotatably supports the input shaft 3 constituting the shaft body S. In this embodiment, the second bearing B2 is disposed so as to support the outer peripheral surface of the input shaft 3 from the outside in the radial direction R. In the example shown in FIG. 1, the second side wall portion 93b of the case 9 has a second bearing support portion 93c. The second bearing support portion 93c is formed in a cylindrical shape protruding to the first axial side L1 so as to overlap with the input shaft 3 in a radial view along the radial direction R, outside the input shaft 3 in the radial direction R. The second bearing B2 is disposed between the inner peripheral surface of the second bearing support portion 93c and the outer peripheral surface of the input shaft 3.

[0037] The third bearing B3 is disposed between the rotor 12 and the first gear 31 in the axial direction L, at a position overlapping with the radial fitting portion 6 in a radial view along the radial direction R. The third bearing B3 rotatably supports the rotor shaft 2 constituting the shaft body S. In this embodiment, the third bearing B3 is disposed so as to support the radial fitting portion 6 from the outside in the radial direction R. Therefore, the third bearing B3 supports the coupling portion 32 of the input shaft 3 forming the radial fitting portion 6 via the connection portion 22 (i.e., the rotor shaft 2) that is fitted into the coupling portion 32. Therefore, it can be said that the third bearing B3 also rotatably supports the input shaft 3 constituting the shaft body S. In this example, the third bearing B3 is disposed so as to support the outer circumferential surface 2b of the rotor shaft 2 from the outside in the radial direction R. The inner circumferential surface F3 of the third bearing B3 is in contact with the outer circumferential surface 2b of the rotor shaft 2. In this example, the third bearing B3 abuts against an outer peripheral surface 2b at an end portion on the second axial side L2 of the connection portion 22. In the example shown in Fig. 1, the partition portion 91 of the case 9 has a third bearing support portion 91a. The third bearing support portion 91a is formed in a cylindrical shape that protrudes toward the first axial side L1 on the outer side in the radial direction R of the connection portion 22 of the rotor shaft 2 so as to overlap with the connection portion 22 when viewed in the radial direction along the radial direction R.

[0038] As shown in FIG. 3, in this embodiment, a step surface 311 facing the axial first side L1 is formed on the input shaft 3 at a position on the axial second side L2 from the end of the axial second side L2 of the rotor shaft 2. The step surface 311 abuts against the third bearing B3 from the axial second side L2. The step surface 311 is formed on the input shaft 3. In this example, the input shaft 3 has a flange portion 33 on which the step surface 311 is formed. The flange portion 33 is adjacent to the connecting portion 32 on the axial second side L2 and is provided so as to protrude outward in the radial direction R from the main body of the input shaft 3. Here, the step surface 311 is a surface facing the axial first side L1 of the flange portion 33. In the example of FIG. 1 and FIG. 3, the flange portion 33 is shaped to expand outward in the radial direction R as it approaches the axial first side L1, and the step surface 311 is a flat surface along the radial direction R and the circumferential direction C. 3, in a state in which the stepped surface 311 abuts against the third bearing B3 from the second axial side L2, a gap in the axial direction L is formed between the end of the rotor shaft 2 on the second axial side L2 and the stepped surface 311. This makes it possible to prevent the thrust load acting on the input shaft 3 from being transmitted to the rotor shaft 2, thereby making it possible to reduce the size of the first bearing B1 abutting against the rotor shaft 2 from the first axial side L1. In the illustrated example, the third bearing B3 is disposed at a position overlapping with the radial fitting portion 6 when viewed in the radial direction R, but is not disposed at a position overlapping with the spline engagement portion 8.

[0039] The counter gear mechanism 51 includes a second gear 511 that meshes with the first gear 31, a third gear 512 that rotates integrally with the second gear 511, and a connecting shaft 513 that connects the second gear 511 and the third gear 512 together.

[0040] The second gear 511 and the third gear 512 are connected to each other via a connecting shaft 513 so as to rotate integrally. In the example shown in FIG. 1, the second gear 511 is connected to the connecting shaft 513 by spline engagement. The third gear 512 is formed integrally with the connecting shaft 513. In the example shown in FIG. 1, the third gear 512 is formed to have a smaller diameter than the second gear 511. The third gear 512 is arranged so that an arrangement area of ​​the third gear 512 in the axial direction L overlaps with an arrangement area of ​​the second bearing B2 in the axial direction L.

[0041] The connecting shaft 513 is formed to extend along the second axis X2. In this embodiment, the connecting shaft 513 is rotatably supported with respect to the case 9 by a first counter bearing B51 and a second counter bearing B52.

[0042] In this embodiment, the first counter bearing B51 is disposed on the first axial side L1 relative to the second gear 511.

[0043] In this embodiment, the first counter bearing B51 is disposed so as to support the outer circumferential surface of the connecting shaft 513 from the outside in the radial direction R. In the example shown in FIG. 1, the partition wall 91 of the case 9 has a fourth bearing support portion 91b. The fourth bearing support portion 91b is formed in a cylindrical shape that protrudes toward the second axial side L2. The first counter bearing B51 is disposed between the inner circumferential surface of the fourth bearing support portion 91b and the outer circumferential surface of the connecting shaft 513.

[0044] In this embodiment, the second counter bearing B52 is disposed on the second axial side L2 relative to the third gear 512.

[0045] In this embodiment, the second counter bearing B52 is disposed so as to support the outer peripheral surface of the connecting shaft 513 from the outside in the radial direction R. In the example shown in FIG. 1, the second side wall portion 93b of the case 9 has a fifth bearing support portion 93d. The fifth bearing support portion 93d is formed in a cylindrical shape recessed toward the second axial side L2 so as to be spaced apart from the third gear 512. In other words, the fifth bearing support portion 93d is formed so as to be recessed toward the second axial side L2 more than the portion of the second side wall portion 93b other than the fifth bearing support portion 93d. As a result, the fifth bearing support portion 93d is formed in a cylindrical shape overlapping with the connecting shaft 513 in a radial view along the radial direction R, on the outer side of the connecting shaft 513 in the radial direction R. The second counter bearing B52 is disposed between the inner peripheral surface of the fifth bearing support portion 93d and the outer peripheral surface of the connecting shaft 513. Thus, in this embodiment, the second counter bearing B52 is disposed on the second axial side L2 with respect to the second bearing B2.

[0046] The differential gear mechanism 52 includes a fourth gear 521 that meshes with the third gear 512. The differential gear mechanism 52 distributes the rotation of the fourth gear 521 to the pair of output members 4.

[0047] In this embodiment, the differential gear mechanism 52 further includes a differential case 522, a pair of pinion gears 523, and a pair of side gears 524. Here, the pair of pinion gears 523 and the pair of side gears 524 are both bevel gears.

[0048] The differential case 522 is a hollow member that houses a pair of pinion gears 523 and a pair of side gears 524. The differential case 522 is connected to the fourth gear 521 so as to rotate integrally therewith.

[0049] The pair of pinion gears 523 are disposed to face each other with a gap therebetween in the radial direction R based on the third axis X3. The pair of pinion gears 523 are attached to a pinion shaft 52a supported to rotate integrally with the differential case 522. Each of the pair of pinion gears 523 is configured to be rotatable (spin on its own axis) about the pinion shaft 52a and rotatable (revolve) about the third axis X3.

[0050] The pair of side gears 524 mesh with the pair of pinion gears 523. The pair of side gears 524 are arranged to rotate about the third axis X3 as a rotation axis. The pair of side gears 524 are arranged to face each other with a gap between them in the axial direction L, sandwiching the pinion shaft 52a therebetween.

[0051] In this embodiment, the differential case 522 is rotatably supported with respect to the case 9 by a first differential bearing B41 and a second differential bearing B42.

[0052] In this embodiment, the first differential bearing B41 is disposed so as to support the end of the differential case 522 on the first axial side L1 from the outside in the radial direction R. In the example shown in FIG. 1, the partition wall 91 of the case 9 has a sixth bearing support portion 94d. The sixth bearing support portion 94d is formed so as to overlap the end of the differential case 522 on the first axial side L1 in the radial direction R, on the outside of the end of the differential case 522 on the first axial side L1, as viewed in the radial direction along the radial direction R. The first differential bearing B41 is disposed between the inner peripheral surface of the sixth bearing support portion 94d and the outer peripheral surface of the end of the differential case 522 on the first axial side L1.

[0053] In this embodiment, the second differential bearing B42 is disposed so as to support the end of the differential case 522 on the second axial side L2 from the outside in the radial direction R. In the example shown in FIG. 1, the fourth side wall portion 94c of the case 9 has a seventh bearing support portion 94e. The seventh bearing support portion 94e is formed so as to overlap the end of the differential case 522 on the second axial side L2 in the radial direction R, on the outside of the end of the differential case 522 on the second axial side L2, as viewed in the radial direction along the radial direction R. The second differential bearing B42 is disposed between the inner peripheral surface of the seventh bearing support portion 94e and the outer peripheral surface of the end of the differential case 522 on the second axial side L2.

[0054] In this embodiment, each of the pair of output members 4 is connected to the side gear 524 so as to rotate integrally with the side gear 524. Each of the pair of output members 4 is connected to the drive shaft DS drivingly connected to the wheel W so as to rotate integrally with the side gear 524. In the example shown in FIG. 1, each of the pair of output members 4 is formed in a cylindrical shape with the third axis X3 as its axis. Then, the output members 4 on the axial first side L1 are connected to each other by spline engagement with a connecting shaft J connected to the drive shaft DS disposed inside in the radial direction R with respect to the output members 4 on the axial second side L2, with the drive shaft DS disposed inside in the radial direction R with respect to the output members 4 on the axial second side L2.

[0055] As described above, the vehicle drive device 100 has the following features: A rotating electric machine 1 having a rotor 12; A rotor shaft 2 fixed to the rotor 12 so as to rotate integrally with the rotor 12; An input shaft 3 arranged coaxially with the rotor shaft 2 and equipped with a first gear 31; An output member 4 that is drivingly connected to the wheels; a power transmission mechanism 5 including a second gear 511 that meshes with the first gear 31 and drivingly connects the first gear 31 and an output member 4; and a case 9 that accommodates the rotating electric machine, the rotor shaft 2, the input shaft 3, and the power transmission mechanism 5. The direction along the axis of the rotor shaft 2 is defined as the axial direction L, the direction perpendicular to the axis is defined as the radial direction R, and the direction going around the axis is defined as the circumferential direction C. The side of the axial direction L on which the rotor 12 is disposed with respect to the first gear 31 is defined as the axial first side L1, and the side of the axial direction L opposite to the axial first side L1 is defined as the axial second side L2. The rotor 12 and the first gear 31 are disposed at different positions in the axial direction L, The rotor shaft 2 and the input shaft 3 are connected to each other so as to rotate integrally with each other via a radial fitting portion 6 that fits in a radial direction R and a spline engagement portion 8 that engages in a circumferential direction C, The rotor shaft 2 and the input shaft 3 are rotatably supported by a first bearing B1, a second bearing B2, and a third bearing B3 at three locations in the axial direction L relative to a case 9. The first bearing B1 is disposed on the first axial side L1 with respect to the rotor 12, The second bearing B2 is disposed on the second axial side L2 with respect to the first gear 31, The third bearing B3 is disposed between the rotor 12 and the first gear 31 in the axial direction L, at a position overlapping with the radial fitting portion 6 when viewed in the radial direction R.

[0056] According to this configuration, the rotor shaft 2 and the input shaft 3 are engaged with each other via the spline engagement portion 8, so that these two shafts can rotate integrally with each other, and the rotor shaft 2 and the input shaft 3 are connected with each other via the radial fitting portion 6, so that the misalignment of the rotational axes of these two shafts can be minimized. Therefore, vibration caused by the misalignment of the rotational axes of the rotor shaft 2 and the input shaft 3 can be reduced. Furthermore, according to this configuration, the rotor shaft 2 and the input shaft 3 are supported by the case 9 via the first bearing B1, the second bearing B2, and the third bearing B3 that is disposed between the rotor 12 and the first gear 31 in the axial direction L and at a position overlapping with the radial fitting portion 6 as viewed in the radial direction, so that it is possible to stably support both the centrifugal force caused by the rotation of the rotor 12 and the reaction force that the first gear 31 receives from the second gear 511. Therefore, it is possible to reduce vibrations caused by these forces.

[0057] As shown in FIG. 3, in this embodiment, the radial fitting portion 6 is a portion where the inner circumferential surface 2a of the rotor shaft 2, which is formed in a cylindrical shape, and the outer circumferential surface 3b of the input shaft 3 are in contact with each other in the radial direction R. The inner peripheral surface F3 of the third bearing B3 is in contact with the outer peripheral surface 2b of the rotor shaft 2, The spline engagement portion 8 is disposed on a first axial side L1 relative to the radial fitting portion 6.

[0058] According to this configuration, the third bearing B3 can support the rotor shaft 2 and the input shaft 3 from the outside in the radial direction R. Therefore, it is easy to simplify the support structure of the rotor shaft 2 and the input shaft 3 by the third bearing B3. Furthermore, with this configuration, the rotor shaft 2 is disposed radially outward of the input shaft 3, and the radial fitting portion 6 is disposed on the second axial side L2, which is closer to the end of the rotor shaft 2 than the spline engagement portion 8, so that it is easy to ensure a wide support interval for the rotor shaft 2 by the first bearing B1 and the third bearing B3. This makes it easy to stably support the heavy rotor 12 and rotor shaft 2. Furthermore, since the rotor shaft 2 is directly supported by the third bearing B3, it is easy to restrict movement of the rotor 12 in the axial direction L.

[0059] As shown in FIG. 3, in this embodiment, a step surface 311 facing the first axial side L1 is formed on the input shaft 3 at a position on the second axial side L2 further than the end of the rotor shaft 2 on the second axial side L2. The step surface 311 abuts against the third bearing B3 from the second axial side L2.

[0060] According to this configuration, the third bearing B3 can support the input shaft 3 in the axial direction L. Therefore, vibrations caused by movement of the input shaft 3 in the axial direction L can be easily suppressed to a small value.

[0061] As shown in FIG. 3, in this embodiment, the vehicle drive device 100 further includes a rotation sensor 7 that detects the rotation of the rotor 12. The rotation sensor 7 includes a sensor stator 71 and a sensor rotor 72 (FIG. 3). In this example, the rotation sensor 7 is configured as a resolver. Thus, when an AC current is passed through a coil provided in the sensor stator 71, the rotation sensor 7 detects the phase of an AC voltage corresponding to the relative angle of the sensor rotor 72 with respect to the sensor stator 71, thereby detecting the rotational position of the rotor 12. Note that the rotation sensor 7 is not limited to a resolver, and can be configured by various sensors such as a Hall element sensor, an encoder, and a magnetic rotation sensor.

[0062] The sensor stator 71 is fixed to a non-rotating member. In this embodiment, the sensor stator 71 is fixed to a partition wall portion 91 (here, a portion of the partition wall portion 91 on the first axial side L1 with respect to the third bearing support portion 91a) of the case 9 serving as a non-rotating member.

[0063] The sensor rotor 72 is connected to rotate integrally with the shaft body S. In this embodiment, the sensor rotor 72 is connected to rotate integrally with the input shaft 3 that constitutes the shaft body S. The sensor rotor 72 is disposed to face the sensor stator 71 from the inside in the radial direction R.

[0064] As shown in Fig. 1, in this embodiment, the rotation sensor 7 is disposed on the outer side in the radial direction R with respect to the rotor shaft 2 and the input shaft 3, and at a position overlapping with the spline engagement portion 8 as viewed in the radial direction along the radial direction R. In the example shown in Fig. 1, a sensor stator 71 of the rotation sensor 7 is disposed on the outer side in the radial direction R with respect to the rotor shaft 2 and the input shaft 3, and at a position overlapping with the spline engagement portion 8 as viewed in the radial direction along the radial direction R. On the other hand, the sensor stator 71 does not overlap with the radial fitting portion 6 as viewed in the radial direction along the radial direction R. In addition, the sensor stator 71 is disposed at a position overlapping with the third bearing B3 as viewed in the axial direction along the first axis X1.

[0065] According to this configuration, the rotation sensor 7 can be disposed by utilizing the space outside in the radial direction R with respect to the region along the first axis X1 in which the spline engagement portion 8 is provided. Therefore, it is easy to reduce the size of the vehicle drive device 100.

[0066] As shown in FIG. 1, FIG. 3, and FIG. 4, the vehicle drive device 100 further includes an oil supply unit 65 that supplies oil to a space inside the radial direction R of the input shaft 3, and an oil passage 68 that connects the inner peripheral surface 3a and the outer peripheral surface 3b of the input shaft 3. In this embodiment, the input shaft 3 is formed in a cylindrical shape with both sides in the axial direction L open. Here, the oil supply unit 65 is an opening portion at the end of the input shaft 3 on the second axial side L2. The oil supply unit 65 is supplied with oil scooped up from an oil reservoir (not shown) formed in the lower part of the case 9, for example. In this embodiment, the oil passage 68 is disposed between the spline engagement unit 8 and the radial fitting unit 6 in the axial direction L. In this example, the oil passage 68 is formed in the connecting unit 32 of the input shaft 3. In the example of FIG. 3, the oil passage 68 is formed along the radial direction R between the spline engagement unit 8 and the radial fitting unit 6 in the axial direction L in the connecting unit 32. Then, the oil supplied from the oil supply unit 65 moves inside (hollow portion) of the input shaft 3 from the second axial side L2 toward the first axial side L1 (i.e., the side of the connecting unit 32), and then passes through the oil passage 68 and is supplied to the spline engagement unit 8 and the radial fitting unit 6. As shown in FIG. 3 and FIG. 4, a gap in the radial direction R is formed between the outer circumferential surface 3b of the input shaft 3 and the inner circumferential surface 2a of the rotor shaft 2 between the spline engagement unit 8 and the radial fitting unit 6 in the axial direction L, and the oil passage 68 is formed so as to open into the gap. Then, the oil supplied from the oil passage 68 to the gap moves to both sides in the axial direction L and is supplied to the spline engagement unit 8 and the radial fitting unit 6, respectively. Note that the oil passage 68 may be arranged at a plurality of locations in the circumferential direction C in the connecting unit 32.

[0067] As shown in FIG. 1 and FIG. 3, in this embodiment, the input shaft 3 is formed in a cylindrical shape. an oil supply unit 65 for supplying oil to an inner space in the radial direction R of the input shaft 3; An oil passage 68 connecting the inner peripheral surface 3a and the outer peripheral surface of the input shaft 3 is further provided. An oil passage 68 is disposed between the spline engagement portion 8 and the radial fitting portion 6 in the axial direction L.

[0068] According to this configuration, oil can be supplied to both the spline engagement portion 8 and the radial fitting portion 6 by using the oil supply portion 65 and the oil passage 68, thereby allowing them to be appropriately lubricated.

[0069] Other embodiments

[0070] (1) In the above embodiment, the rotor shaft 2 and the input shaft 3 are connected by inserting the connecting portion 32 of the input shaft 3 into the connecting portion 22 from the opening on the second axial side L2 of the connecting portion 22, but the present invention is not limited to this. The rotor shaft 2 and the input shaft 3 can also be connected by inserting the connecting portion 22 of the rotor shaft 2 into the connecting portion 32 from an opening formed in the connecting portion 32 of the input shaft 3. In this case, the radial fitting portion 6 is a portion where the outer circumferential surface 2b of the rotor shaft 2 (here, the outer circumferential surface of the connecting portion 22) and the inner circumferential surface 3a of the input shaft 3 (here, the inner circumferential surface of the connecting portion 32) are in contact in the radial direction R.

[0071] (2) In the above embodiment, the vehicle drive device 100 is described as having a three-axis configuration in which the rotating electric machine 1, the counter gear mechanism 51, and the differential gear mechanism 52 are arranged on different parallel axes. However, the vehicle drive device 100 may be configured as a two-axis configuration in which the planetary gear mechanism is arranged coaxially with the rotating electric machine 1, and the rotating electric machine 1 and the differential gear mechanism 52 are arranged on different parallel axes. In the above embodiment, the power transmission mechanism 5 is described as having the counter gear mechanism 51 and the differential gear mechanism 52. However, the power transmission mechanism 5 may be configured as having only one of the counter gear mechanism 51 and the differential gear mechanism 52, or the power transmission mechanism 5 may be configured as having neither the counter gear mechanism 51 nor the differential gear mechanism 52. In addition, the vehicle drive device 100 may be configured as having an internal combustion engine functioning as a driving force source for the wheels W in addition to the rotating electric machine 1, that is, the vehicle drive device 100 may be mounted on a hybrid vehicle.

[0072] (3) In the above embodiment, the spline engagement portion 8 is disposed on the first axial side L1 with respect to the radial fitting portion 6, but the present invention is not limited to this. The spline engagement portion 8 may be disposed on the second axial side L2 with respect to the radial fitting portion 6.

[0073] (4) In the above embodiment, the step surface 311 is formed on the input shaft 3, and the step surface 311 abuts against the third bearing B3 from the second axial side L2. However, the present invention is not limited to this. The step surface 311 may not be formed on the input shaft 3. In this case, the surface abutting against the third bearing B3 from the second axial side L2 may be formed on, for example, the first gear 31, instead of the input shaft 3. For example, the surface of the first gear 31 facing the first axial side L1 may be the surface abutting against the third bearing B3 from the second axial side L2. In the case of such a configuration, it is not necessary to provide the flange portion 33 on the input shaft 3, and therefore it is easy to reduce the size of the vehicle drive device 100.

[0074] (5) In the above embodiment, the vehicle drive device 100 includes the oil passage 68 that connects the inner circumferential surface 3a and the outer circumferential surface of the input shaft 3, and the oil passage 68 is disposed between the spline engagement portion 8 and the radial fitting portion 6 in the axial direction L. However, the present invention is not limited to this configuration, and the position at which the oil passage 68 is disposed can be changed as appropriate. For example, the oil passage 68 can be disposed on the second axial side L2 with respect to the radial fitting portion 6, or on the first axial side L1 with respect to the spline engagement portion 8.

[0075] (6) Note that the configurations disclosed in each of the above-described embodiments can be applied in combination with configurations disclosed in other embodiments (including combinations of the embodiments described as other embodiments) as long as no contradiction occurs. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0076] 1: rotating electric machine, 2: rotor shaft, 2a: inner peripheral surface of rotor shaft, 3: input shaft, 3a: inner peripheral surface of input shaft, 3b: outer peripheral surface of input shaft, 4: output member, 5: power transmission mechanism, 6: radial fitting portion, 8: spline engagement portion, 9: case, 10: rotating electric machine, 12: rotor, 31: first gear, 65: oil supply portion, 68: oil passage, 100: vehicle drive device, 311: step surface, 511: second gear, B1: first bearing, B2: second bearing, B3: third bearing, C: circumferential direction, F3: inner peripheral surface of third bearing, L: axial direction, L1: first axial side, L2: second axial side, R: radial direction, W: wheel, X1: first shaft, X2: second shaft, X3: third shaft

Claims

1. A rotating electric machine having a rotor; a rotor shaft fixed to the rotor so as to rotate integrally with the rotor; an input shaft arranged coaxially with the rotor shaft and including a first gear; An output member drivingly connected to the wheels; a power transmission mechanism including a second gear that meshes with the first gear and drivingly connects the second gear and the output member; a case that accommodates the rotating electric machine, the rotor shaft, the input shaft, and the power transmission mechanism, a direction along the axis of the rotor shaft is defined as an axial direction, a direction perpendicular to the axis is defined as a radial direction, a direction going around the axis is defined as a circumferential direction, a side in the axial direction where the rotor is disposed with respect to the first gear is defined as an axial first side, and a side in the axial direction opposite to the axial first side is defined as an axial second side, the rotor and the first gear are disposed at different positions in the axial direction, the rotor shaft and the input shaft are connected to each other so as to rotate integrally with each other via a radial fitting portion that fits in the radial direction and a spline engagement portion that engages in the circumferential direction, the rotor shaft and the input shaft are rotatably supported with respect to the case at three locations in the axial direction by a first bearing, a second bearing, and a third bearing, the first bearing is disposed on a first side in the axial direction with respect to the rotor, the second bearing is disposed on the second axial side with respect to the first gear, The vehicle drive device, wherein the third bearing is disposed between the rotor and the first gear in the axial direction and at a position overlapping with the radial fitting portion as viewed in the radial direction along the radial direction.

2. the radial fitting portion is a portion where an inner circumferential surface of the rotor shaft, which is formed in a cylindrical shape, and an outer circumferential surface of the input shaft are in contact with each other in the radial direction, an inner circumferential surface of the third bearing is in contact with an outer circumferential surface of the rotor shaft, The vehicle drive device according to claim 1 , wherein the spline engagement portion is disposed on the first axial side with respect to the radial fitting portion.

3. a step surface facing the first axial side is formed on the input shaft at a position on the second axial side relative to an end portion of the rotor shaft on the second axial side, The vehicle drive device according to claim 2 , wherein the step surface abuts against the third bearing from the second axial side.

4. The input shaft is formed in a cylindrical shape, an oil supply unit that supplies oil to the radially inner space of the input shaft; An oil passage connecting the inner circumferential surface and the outer circumferential surface of the input shaft, The vehicle drive device according to claim 1 , wherein the oil passage is disposed between the spline engagement portion and the radially fitting portion in the axial direction.

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