Vehicle drive systems

Abstract

When bearings and multiple gears are arranged along the axial direction, the axial dimension is shortened, enabling miniaturization of the vehicle's drive system. [Solution] The vehicle drive unit 1 has a symmetric bearing 60 that rotatably supports a first gear 31 and a second gear 32, which are arranged on a symmetric axis A2 positioned in a position overlapping with the rotating electric machine 2 in an axial view. The symmetric bearing 60 comprises a plurality of rolling elements 64 and a symmetric race 66 which is either an outer race 63 or an inner race. The first gear 31 comprises a first gear tooth portion 33 and a first gear support portion 34. The plurality of rolling elements 64 are arranged to roll between a first rolling surface 67 formed on the symmetric race 66 and a second rolling surface 68 formed on the first gear support portion 34 or the case-side support portion 96 so as to face the first rolling surface 67. They are also arranged radially inward R1 from the first gear tooth portion 33 and overlapping with the first gear tooth portion 33 in a radial view.

Description

Technical Field

[0001] The present invention relates to a vehicle drive device.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2023-20380 discloses a vehicle drive device (1) having a parallel three-axis configuration in which a rotating electric machine (40) is arranged on a first shaft (A1), a counter gear mechanism (20) is arranged on a second shaft (A2), and an output differential gear device (30) is arranged on a third shaft (A3). (In the background art, the reference numerals in parentheses refer to the cited documents.) The counter gear mechanism (20) includes a counter shaft (21), a first gear (22), and a second gear (23). The counter shaft (21), the first gear (22), and the second gear (23) rotate integrally. On the second shaft (A2), a bearing for rotatably supporting the counter shaft (21), the first gear (22), and the second gear (23) are arranged along the axial direction along the counter shaft (21).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, when the bearing, the first gear, and the second gear are arranged in series along the axial direction, the length of the axial arrangement region is restricted by the axial lengths of the bearing, the first gear, and the second gear, etc., and it is difficult to shorten the axial length of the counter gear mechanism.

[0005] In view of the above background, when a bearing and a plurality of gears are arranged along the axial direction, it is desired to shorten the axial dimension and realize miniaturization of the vehicle drive device.

Means for Solving the Problems

[0006] A vehicle drive system in view of the above, comprising: a rotating electric machine; an output member driven to a wheel; a power transmission mechanism for transmitting driving force between the rotor of the rotating electric machine and the output member; and a case housing the rotating electric machine and the power transmission mechanism, wherein the power transmission mechanism comprises: a first gear and a second gear arranged on a symmetric axis; and a symmetric bearing that rotatably supports the first gear and the second gear with respect to the case, the direction along the symmetric axis being the axial direction and the direction perpendicular to the symmetric axis being the radial direction, the symmetric axis being positioned in a position that overlaps with the rotating electric machine in an axial view along the axial direction, and the first gear having a first gear tooth portion that meshes with the teeth of other gears, and the first gear tooth portion facing the radial direction The case comprises a first gear support portion that supports the target bearing from the inside, and the case comprises a case-side support portion that supports the target bearing, and the target bearing comprises a plurality of rolling elements and a target race which is either an outer race that supports the plurality of rolling elements from the outside in the radial direction or an inner race that supports the plurality of rolling elements from the inside in the radial direction, and the plurality of rolling elements are arranged to roll between a first rolling surface formed on the target race and a second rolling surface formed on the first gear support portion or the case-side support portion so as to be opposite to the first rolling surface, and the plurality of rolling elements are arranged radially inside the first gear teeth and overlapping with the first gear teeth in a radial view along the radial direction.

[0007] With this configuration, if there is a target race that supports multiple rolling elements in the target bearing, which is either an outer race or an inner race, the other race is unnecessary, making it easier to keep the radial dimensions of the target bearing small. As a result, without increasing the gear diameter of the first gear, the multiple rolling elements of the target bearing can be positioned radially inward from the teeth of the first gear and overlapping with the teeth of the first gear in a radial view. Furthermore, because the multiple rolling elements are arranged in this way, it is easier to keep the axial dimensions of the region on the target axis where the first gear, second gear, and target bearing are arranged small. By keeping the axial dimensions small in this way, when the target axis overlaps with the rotating electric machine in an axial view, as in this configuration, and the first gear, second gear, and target bearing are arranged axially aligned with the rotating electric machine, it is easier to reduce the overall axial dimensions of the vehicle drive system. In other words, with this configuration, when bearings and multiple gears are arranged along the axial direction, the axial dimension can be shortened, and the vehicle drive system can be made more compact.

[0008] Further features and advantages of the vehicle drive system will become clear from the following description of exemplary and non-limiting embodiments, which will be illustrated with reference to the drawings. [Brief explanation of the drawing]

[0009] [Figure 1] Skeleton diagram of a vehicle drive system [Figure 2] Cross-sectional view of a vehicle drive system [Figure 3] Partially enlarged cross-sectional view of a vehicle drive system [Modes for carrying out the invention]

[0010] Embodiments of the vehicle drive system will be described below with reference to the drawings. As shown in the skeleton diagram of Figure 1 and the axial cross-sectional view of Figure 2, the vehicle drive system 1 comprises a rotating electric machine 2 which is the driving force source for the wheels 10, a power transmission mechanism 5 which transmits driving force between the rotor 21 of the rotating electric machine 2 and an output member 49 driven to the wheels 10, and a case 9 which houses the rotating electric machine 2 and the power transmission mechanism 5. The rotating electric machine 2 is located on the first shaft A1. The power transmission mechanism 5 comprises a counter gear mechanism 3 which functions as a reduction gear and is located on the second shaft A2, which is a separate shaft parallel to the first shaft A1, and a differential gear device 4 which is located on the third shaft A3, which is a separate shaft parallel to the first shaft A1 and the second shaft A2. In this embodiment, the second shaft A2 on which the counter gear mechanism 3 is located is referred to as the "target shaft".

[0011] In this specification, the direction along the mutually parallel first axis A1, second axis A2, and third axis A3 is defined as the axial direction L, with one side of the axial direction L being the first axial direction L1 and the other side being the second axial direction L2. Furthermore, the direction perpendicular to each axis is defined as the radial direction R with respect to each axis, with the direction toward the axis being the radially inner direction R1 and the direction toward the axis being the radially outer direction R2. To clarify which axis is being used as the reference, individual names may be used, for example, referring to the radial direction R with respect to the first axis A1 on which the rotor 21 is located as the "rotor axis radial direction." In addition, when a specific axis is being targeted, that specific axis (axis center) may be referred to as the target axis (target axis center) and the direction may be referred to as the "target axis radial direction."

[0012] Furthermore, in this specification, a drive connection refers to a state in which two rotating elements are connected in a manner that enables the transmission of driving force. A drive connection includes a state in which the two rotating elements are connected so as to rotate as a whole, or a state in which the two rotating elements are connected in a manner that enables the transmission of driving force via one or more members (power transmission members). Such power 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. Such power transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices.

[0013] The rotating electric machine 2, comprising a rotor 21 and a stator 22, is a traction motor that serves as the driving force source for the vehicle's wheels 10. The rotating electric machine 2 functions as an electric motor that drives the wheels 10 by receiving power from a DC power supply (not shown), and also functions as a generator that generates power from the wheels 10 and supplies power to the DC power supply. The rotating electric machine 2 is driven and controlled by a control device (not shown), for example, by current feedback control using a known vector control method. The control device drives and controls the rotating electric machine 2 by controlling an inverter (not shown) that converts power between the DC on the DC power supply side and the AC on the rotating electric machine 2 side. In this control, the control device uses the value of the current flowing through the rotating electric machine 2, the rotational speed of the rotor 21, and the rotational position of the rotor 21 as parameters. The current is detected by a current sensor (not shown) and provided to the control device. The rotational speed and rotational position of the rotor 21 are detected by rotation sensors 7 (see Figures 2 and 3), such as resolvers and inductive position sensors, and provided to the control device. The rotation sensors 7 are positioned on the rotor axis (first axis A1), which is the rotational axis of the rotor 21.

[0014] An input member 29 is connected to the rotor shaft 20, which is connected to the rotor 21 and rotates integrally with the rotor 21, by means of a spline coupling or the like. In this embodiment, the input member 29 rotates integrally with the rotor 21 and the rotor shaft 20. As shown in Figure 2, in this embodiment, the rotor shaft 20 is a hollow cylindrical member and is rotatably supported from the radially inner R1 relative to the case 9 by a pair of rotor bearings 8 located at two locations in the axial direction L. When distinguishing between the pair of rotor bearings 8, the rotor bearing 8 located on the axial second side L2 (the side of the power transmission mechanism 5 relative to the rotating electric machine 2) is referred to as the first rotor bearing 81, and the rotor bearing 8 located on the axial first side L1 is referred to as the second rotor bearing 82. The input member 29 is inserted into the radially inner R1 of the hollow rotor shaft 20, and the radially inner R1 of the rotor shaft 20 and the radially outer R2 of the input member 29 are connected by a spline coupling. The input member 29 is located on the axial second side L2 relative to the rotor shaft 20.

[0015] An input gear 28 is positioned on the first shaft A1, connected to the rotor 21 so as to rotate integrally with the rotor 21. In this embodiment, the input gear 28 is integrally formed with the input member 29, which rotates integrally with the rotor 21, using the same material as the input member 29. However, the input gear 28, formed from a separate material from the input member 29, may be connected to the input member 29 by welding, spline coupling, or the like, so that the input gear 28 and the input member 29 are integrally configured. The power transmission mechanism 5 includes the input member 29 and the input gear 28. The power transmission mechanism 5 may further include a rotor shaft 20.

[0016] The counter gear mechanism 3 comprises a first counter gear 31 (first gear) and a second counter gear 32 (second gear) which has a smaller diameter than the first counter gear 31. The second counter gear 32 is positioned axially on the second side L2 relative to the first counter gear 31. The first counter gear 31 meshes with the input gear 28. The first counter gear 31 and the second counter gear 32 are connected to the counter shaft 30.

[0017] The relatively small-diameter second counter gear 32 is integrally formed with the counter shaft 30. In this embodiment, the second counter gear 32 is illustrated as being integrally formed with the counter shaft 30 by a member of the same material as the counter shaft 30. However, the second counter gear 32 may be formed from a separate member from the counter shaft 30 and connected to the counter shaft 30 in a way that prevents separation, for example by welding.

[0018] The relatively large-diameter first counter gear 31 is formed from a separate component from the counter shaft 30. The counter shaft 30 is equipped with an engaging portion 38 that protrudes axially in the first direction L1 relative to the second counter gear 32. The inner cylindrical portion 37 of the first counter gear 31 is connected to the counter shaft 30 by engaging with the engaging portion 38, for example by a spline coupling, while its relative rotation with respect to the counter shaft 30 is restricted. The counter shaft 30 can be described as a connecting shaft that is positioned on the second shaft A2 (symmetric axis) and connects the first counter gear 31 and the second counter gear 32. In this embodiment, the second shaft A2 is positioned in a location that overlaps with the rotating electric machine 2 in an axial view along the axial direction L. Therefore, the first counter gear 31 and the second counter gear 32 are also positioned in a location that overlaps with the rotating electric machine 2 in an axial view.

[0019] Furthermore, regarding the arrangement of the two members (including cases where one is a virtual axis), "overlapping in a specific viewing direction (e.g., axial viewing)" means that when a virtual line parallel to the line of sight (in this example, axial L) is moved in each direction perpendicular to the line of sight (in this example, axial L) (in this example, radial R), the region in which the virtual line intersects both members (for example, the rotating electric machine 2 and the counter shaft 30 (second axis A2)) exists in at least a portion of the two members.

[0020] As shown in FIG. 3, the first counter gear 31 includes a first gear tooth portion 33 that meshes with the tooth portion of another gear (input gear 28 in this embodiment), and a first gear support portion 34 that supports the first gear tooth portion 33 from the radial inner side R1. The first gear support portion 34 includes a cylindrical outer cylindrical portion 35 located on the radial outer side R2 and having the first gear tooth portion 33 formed on its outer peripheral surface, a cylindrical inner cylindrical portion 37 disposed on the radial inner side R1 with respect to the outer cylindrical portion 35, and a connecting portion 36 that connects the outer cylindrical portion 35 and the inner cylindrical portion 37 in the radial direction R.

[0021] The differential gear device 4 includes a differential input gear 41 that meshes with the second counter gear 32, and a differential gear mechanism 40 that distributes the driving force transmitted to the differential input gear 41 to a pair of output members 49. In this embodiment, the differential gear mechanism 40 is a bevel gear mechanism including a plurality of differential pinion gears 43 housed in a differential case 42 that rotates integrally with the differential input gear 41, and a pair of differential side gears 44 housed in the differential case 42 and meshing with the plurality of differential pinion gears 43. The pair of differential side gears 44 respectively correspond to the output members 49. As shown in FIG. 1, the pair of differential side gears 44 (output members 49) are respectively connected to the drive shafts 48. The pair of wheels 10 are drivingly connected to the pair of differential side gears 44 via the pair of drive shafts 48.

[0022] Note that the differential gear device 4 may be configured to include a differential gear mechanism using a planetary gear mechanism, not limited to a bevel gear mechanism. Also, in this embodiment, an example is shown in which the power transmission mechanism 5 includes the differential gear device 4 and distributes the power from the rotary electric machine 2 to the pair of wheels 10. However, a form in which the power from the rotary electric machine 2 is transmitted to one wheel 10 without including the differential gear device 4 may also be used.

[0023] The countershaft 30 is rotatably supported with respect to the case 9 from the radially outer side R2 of the countershaft 30 by a pair of countershaft bearings 6 arranged at two positions in the axial direction L. The pair of countershaft bearings 6 can also be said to be bearings that rotatably support the first counter gear 31 and the second counter gear 32 with respect to the case 9. When distinguishing between the pair of countershaft bearings 6, the countershaft bearing 6 arranged on the first side L1 in the axial direction is referred to as the first countershaft bearing 61, and the countershaft bearing 6 arranged on the second side L2 in the axial direction is referred to as the second countershaft bearing 62. In the present embodiment, the first countershaft bearing 61 is referred to as the "target bearing 60". On the second shaft A2 (target shaft), the first countershaft bearing 61, the first counter gear 31, the second counter gear 32, and the second countershaft bearing 62 are arranged in this order from the first side L1 in the axial direction toward the second side L2 in the axial direction.

[0024] The power transmission mechanism 5 includes at least the first counter gear 31 and the second counter gear 32 arranged on the second shaft A2 (target axis center), and the target bearing 60 (first countershaft bearing 61) that rotatably supports the first counter gear 31 and the second counter gear 32 with respect to the case 9. The case 9 includes a support portion that supports the bearing. Here, the support portion that supports the first countershaft bearing 61, which is the target bearing 60, is referred to as the case-side support portion 96.

[0025] A bearing generally comprises multiple rolling elements, an inner race supporting the multiple rolling elements from the radially inner R1, and an outer race supporting the multiple rolling elements from the radially outer R2. The target bearing 60 is configured to have only one of the inner race or the outer race. In this embodiment, as shown in Figure 3, the first counter bearing 61, which is the target bearing 60, is configured to have multiple rolling elements 64 and an outer race 63 supporting the multiple rolling elements 64 from the radially outer R2, and does not have an inner race. Although not shown in the example, the target bearing 60 may also be configured to have multiple rolling elements 64 and an inner race supporting the multiple rolling elements 64 from the radially inner R1, without an outer race. Here, the race that the target bearing 60 has among the inner race and the outer race is referred to as the "target race 66". In this embodiment, the outer race 63 supported by the case-side support portion 96 is the target race 66.

[0026] Multiple rolling elements 64 are arranged to roll between a first rolling surface 67 formed on the target race 66 and a second rolling surface 68 facing the first rolling surface 67. Generally, the second rolling surface 68 is formed on a race (in this case, an inner race) that is paired with the target race 66, but as described above, the target bearing 60 does not have an inner race. Therefore, the second rolling surface 68 is formed on a member that supports the target bearing 60. As shown in Figure 3, in this embodiment, the second rolling surface 68 is formed on the first gear support portion 34. Specifically, the second rolling surface 68 is formed on the outer circumferential surface of the radially outer radius R2 of the inner cylindrical portion 37 of the first gear support portion 34. That is, the target bearing 60 is located between the inner cylindrical portion 37 of the first gear support portion 34 and the radial radius R of the case-side support portion 96. Multiple rolling elements 64 are positioned radially inward R1 from the first gear teeth 33 and overlapping with the first gear teeth 33 in a radial view along the radial direction R.

[0027] As described above, the target race 66 may be an inner race. For example, the inner race on which the first rolling surface 67 is formed may be supported by the outer circumferential surface of the radially outer R2 of the inner cylindrical portion 37, and the second rolling surface 68 may be formed on the inner circumferential surface of the radially inner R1 of the case-side support portion 96. In this case as well, the target bearing 60 is located between the inner cylindrical portion 37 of the first gear support portion 34 and the radial R of the case-side support portion 96. Furthermore, the multiple rolling elements 64 are arranged at a position radially inner R1 with respect to the first gear teeth portion 33, and overlapping with the first gear teeth portion 33 in a radial view along the radial R.

[0028] Furthermore, the target bearing 60 may be located between the outer cylindrical portion 35 of the first gear support portion 34 and the radial R of the case-side support portion 96. Here, if the target race 66 is an inner race, it is preferable that the inner race on which the first rolling surface 67 is formed is supported by the outer circumferential surface of the radially outer R2 of the case-side support portion 96, and that a second rolling surface 68 is formed on the inner circumferential surface of the radially inner R1 of the outer cylindrical portion 35 of the first gear support portion 34. In this case as well, the multiple rolling elements 64 are arranged at a position that is radially inner R1 with respect to the first gear teeth portion 33 and overlaps with the first gear teeth portion 33 in a radial view along the radial R.

[0029] In a configuration where the target bearing 60 is located between the radial R of the outer cylindrical portion 35 of the first gear support portion 34 and the case-side support portion 96, the target race 66 may be an outer race. In this case, it is preferable that the outer race on which the first rolling surface 67 is formed is supported by the inner circumferential surface of the radially inner R1 of the outer cylindrical portion 35 of the first gear support portion 34, and that a second rolling surface 68 is formed on the outer circumferential surface of the radially outer R2 of the case-side support portion 96. In this case as well, the plurality of rolling elements 64 are arranged at a position that is radially inner R1 with respect to the first gear teeth portion 33 and overlaps with the first gear teeth portion 33 in a radial view along the radial R.

[0030] As illustrated, in addition to the various forms shown, the multiple rolling elements 64 are arranged to roll between a first rolling surface 67 formed on the target race 66 and a second rolling surface 68 formed on the first gear support portion 34 (including the inner cylindrical portion 37 and the outer cylindrical portion 35) or the case-side support portion 96, facing the first rolling surface 67. The multiple rolling elements 64 are arranged radially inward R1 relative to the first gear teeth 33 and are positioned to overlap with the first gear teeth 33 in a radial view. If at least a portion of the multiple rolling elements 64 overlap with the first gear teeth 33 in a radial view, then at least a portion of the target race 66 and at least a portion of the case-side support portion 96 also overlap. For example, when it is said that the target bearing 60 overlaps in a radial view, it means that at least a portion of the multiple rolling elements 64, at least a portion of the target race 66, and at least a portion of the case-side support portion 96 overlap.

[0031] In this way, by eliminating either the inner race or the outer race, the radial radius R of the target bearing 60 can be kept small. Therefore, without increasing the gear diameter of the first counter gear 31, the multiple rolling elements 64 can be positioned radially inward R1 from the first gear teeth 33 and overlapping with the first gear teeth 33 in a radial view. Furthermore, because the target bearing 60, which includes the multiple rolling elements 64, is arranged in this manner, the dimensions of the axial region L on the second shaft A2, which is the target axis, where the first counter gear 31, the second counter gear 32, and the target bearing 60 are arranged can be kept small. By reducing the axial dimension L, it becomes easier to reduce the overall axial dimension L of the vehicle drive unit 1.

[0032] Furthermore, as shown in Figure 2, the input gear 28, the first counter gear 31, the second counter gear 32, and the differential input gear 41 are arranged on one side of the axial direction L (in this embodiment, the second axial side L2) relative to the rotating electric machine 2. In addition, the input gear 28, the first counter gear 31, and the second counter gear 32 are positioned in a location that overlaps with the rotating electric machine 2 in an axial view. In this configuration, where the rotating electric machine 2 and the gears of the power transmission mechanism 5 are arranged along the axial direction L, it is easy to reduce the overall axial direction L of the vehicle drive unit 1 by keeping the axial direction L of the region on the symmetric axis A2 in which the first counter gear 31, the second counter gear 32, and the symmetric bearing 60 are arranged small.

[0033] As described above with reference to Figure 3, in this embodiment, the target race 66 is the outer race 63, and the second rolling surface 68 is formed on the outer circumferential surface of the inner cylindrical portion 37. The target bearing 60 and the case-side support portion 96 are positioned between the outer cylindrical portion 35 and the inner cylindrical portion 37 in the radial direction R, and overlapping with the outer cylindrical portion 35 and the inner cylindrical portion 37 in a radial view. As shown in Figure 3, the distance d1 between the case-side support portion 96 and the outer cylindrical portion 35 in the radial direction R is smaller than the thickness d2 of the outer race 63 in the radial direction R. Note that this distance d1 is not limited to the distance between surfaces parallel to the axial direction L, but may also be the distance between two surfaces where one or both surfaces are inclined with respect to the axial direction L. If at least one surface is inclined with respect to the axial direction L, it is preferable to set the distance d1 to the point where the distance between the two surfaces in the radial direction R is closest.

[0034] If the target bearing 60 also has an inner race, the thickness of the radial radius R of the inner race is often about the same as that of the outer race 63. Therefore, the thickness d2 of the radial radius R of the outer race 63, which is compared with the distance d1 of the radial radius R between the case-side support portion 96 and the outer cylindrical portion 35, can be said to be the thickness of the radial radius R of the inner race that is expected when the target bearing 60 also has an inner race. If the target bearing 60 has an inner race, the dimension of the radial radius R of the target bearing 60 increases, and in order to position the target bearing 60 between the radial radius R of the outer cylindrical portion 35 and the inner cylindrical portion 37, and in a position that overlaps with the outer cylindrical portion 35 and the inner cylindrical portion 37 in a radial view, measures such as increasing the diameter of the first counter gear 31 are necessary. By not having an inner race for the target bearing 60, the diameter of the first counter gear 31 can be maintained while the rolling elements 64 and the first gear teeth 33 can overlap in a radial view. In this embodiment, while suppressing the increase in the radial dimension R of the vehicle drive unit 1 due to the increase in the gear diameter of the first counter gear 31, the arrangement area of ​​the target bearing 60 in the axial direction L is shared with the first counter gear 31, making it easier to keep the axial dimension L of the vehicle drive unit 1 small.

[0035] The counter gear mechanism 3 is arranged in the order of first counter gear 31 and second counter gear 32, from the first axial side L1 to the second axial side L2. The target bearing 60 and the case-side support portion 96 are positioned on the first axial side L1 with respect to the connecting portion 36 of the first counter gear 31. That is, the target bearing 60 and the case-side support portion 96 are positioned on the opposite side from the second counter gear 32 in the axial direction L, with respect to the connecting portion 36. Therefore, the first counter gear 31 can be easily positioned without interfering with the arrangement of the second counter gear 32 and the input gear 28 that meshes with the second counter gear 32.

[0036] Furthermore, in this embodiment, the first counter gear 31 is formed from a separate component from the counter shaft 30 and is connected to the counter shaft 30 so as to rotate integrally with the counter shaft 30. The first counter gear 31, formed as a separate component, includes a first gear support portion 34. As described above with reference to Figure 3, when forming a second rolling surface 68 on the outer circumferential surface of the inner cylindrical portion 37 of the first gear support portion 34, it is easier to form the second rolling surface 68 when the first counter gear 31 is a separate component from the counter shaft 30 compared to when the first counter gear 31 is the same component as the counter shaft 30. Whether the second rolling surface 68 is integrally formed by molding during the manufacturing of the first counter gear 31 or when the second rolling surface 68 is formed on the first counter gear 31 by additional processing, it is easier to form the second rolling surface 68.

[0037] As described above, the rotor shaft 20, which is connected to the rotor 21 and rotates integrally with the rotor 21, is supported at two locations in the axial direction L by a pair of rotor bearings 8. The case 9 is provided with support parts for supporting the rotor bearings 8. The vehicle drive unit 1 is equipped with a rotation sensor 7 for detecting the rotation of the rotor 21, and in this embodiment, this rotation sensor 7 is positioned so as to overlap radially with one of the pair of rotor bearings 8. As shown in Figures 2 and 3, in this embodiment, of the pair of rotor bearings 8, the first rotor bearing 81 overlaps radially with the rotation sensor 7. Also, as shown in Figure 3, the support part of the case 9 that supports the rotor bearing 8 and supports the first rotor bearing 81 is referred to as the rotor bearing support part 98. Of the pair of rotor bearings 8, the bearing that overlaps radially with the rotation sensor 7 may be referred to as the "target rotor bearing," and the part of the case 9 that supports the target rotor bearing may be referred to as the "target rotor bearing support part."

[0038] The first rotor bearing 81, like the target bearing 60 described above, comprises a plurality of rotor bearing rolling elements 84 and either an outer race that supports the plurality of rotor bearing rolling elements 84 from the radially outer R2 (outside the rotor axis radial direction (R) (R2)) with respect to the first shaft A1, or an inner race that supports the plurality of rotor bearing rolling elements 84 from the radially inner R1 (inside the rotor axis radial direction (R) (R1)), but not the other. In this embodiment, the first rotor bearing 81 comprises a plurality of rotor bearing rolling elements 84 and a rotor bearing inner race 85 that supports the plurality of rotor bearing rolling elements 84 from the radially inner R1, and does not have a rotor bearing outer race that supports the plurality of rotor bearing rolling elements 84 from the radially outer R2. The race (in this case, the rotor bearing inner race 85) provided by the first rotor bearing 81 (target rotor bearing) may be referred to as the "target rotor bearing race".

[0039] Multiple rotor bearing rolling elements 84 are arranged to roll between a first rotor bearing rolling surface 87 formed on one of the outer and inner races of the first rotor bearing 81 (the target rotor bearing race) and a second rotor bearing rolling surface 88 formed on the rotor shaft 20 or rotor bearing support 98 so as to face the first rotor bearing rolling surface 87. In this embodiment, the first rotor bearing 81 is equipped with a rotor bearing inner race 85, and the multiple rotor bearing rolling elements 84 are arranged to roll between a first rotor bearing rolling surface 87 formed on the rotor bearing inner race 85 and a second rotor bearing rolling surface 88 formed on the rotor shaft 20 so as to face the first rotor bearing rolling surface 87. As shown in Figure 3, the first rotor bearing 81 and the rotation sensor 7 overlap in a radial view (rotor shaft radial view) with respect to the first shaft A1.

[0040] Similar to the target bearing 60 described above, the first rotor bearing 81 may be configured with only the rotor bearing outer race, not just the rotor bearing inner race 85. Therefore, the rotor bearing first rolling surface 87 may also be provided on the rotor bearing outer race. Furthermore, the rotor bearing second rolling surface 88 may be formed on the rotor bearing support portion 98, not just on the rotor shaft 20. Specific examples can be modified in the same way as the above-described form for the target bearing 60, and those skilled in the art can easily infer the modifications; therefore, a detailed explanation is omitted.

[0041] In this way, by having only one of the outer race and the inner race as races supporting the multiple rotor bearing rolling elements 84, and omitting the other, it is easy to keep the radial R dimension of the first rotor bearing 81 small. Therefore, without increasing the diameter of the rotation sensor 7, the first rotor bearing 81, which includes the multiple rotor bearing rolling elements 84, can be positioned radially inward R1 from the rotation sensor 7 and overlapping with the rotation sensor 7 in a radial view. With the first rotor bearing 81 positioned in this way, it is easy to keep the axial L dimension of the region on the first axis A1, which is the rotor axis, where the rotor 21, rotation sensor 7, and input gear 28 are arranged small.

[0042] Other embodiments will be described below. Note that the configurations of each embodiment described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments, as long as no inconsistencies arise.

[0043] (1) The configuration of the power transmission mechanism 5 is not limited to the above-described form (parallel three-axis configuration). For example, the vehicle drive system 1 may be a two-axis configuration (folded two-axis configuration) in which the differential gear device 4 is arranged on the first axis A1. Furthermore, although the above example illustrates the vehicle drive system 1 of an EV (electric vehicle) in which the driving force source for the wheels 10 is a rotating electric machine 2, the vehicle drive system 1 may also be a hybrid drive system of an HV (hybrid vehicle) equipped with other driving force sources such as an internal combustion engine in addition to the rotating electric machine 2.

[0044] (2) In the above description, an example was given in which the second shaft A2 is the symmetric axis. However, if multiple gears are arranged coaxially, the symmetric axis may be any other shaft. For example, if a gear other than the input gear 28 is arranged on the first shaft A1, the symmetric axis may be the first shaft A1. Also, in a vehicle drive system 1 equipped with multiple shafts, multiple shafts may be symmetric axes.

[0045] (3) In the above, an example was given in which the first counter bearing 61 of the pair of counter bearings 6 is designated as the target bearing 60. However, if the arrangement positions of the large-diameter gear (here, the first counter gear 31) and the small-diameter gear (here, the second counter gear 32) in the counter gear mechanism 3 in the axial direction L are reversed from the configurations illustrated in Figures 1 to 3, the second counter bearing 62 may be designated as the target bearing 60. Furthermore, if a distance can be secured in the radial direction R between the teeth of the relatively small-diameter second counter gear 32 and the counter shaft 30 to accommodate one race and multiple rolling elements, both the first counter bearing 61 and the second counter bearing 62 may be designated as the target bearing 60.

[0046] (4) In the above example, a configuration was given in which the first rotor bearing 81 and the rotation sensor 7, which are located on the second axial side L2, which is the side of the power transmission mechanism 5 relative to the rotating electric machine 2 in the axial direction L, overlap in a radial view. However, a configuration in which the second rotor bearing 82 and the rotation sensor 7, which are located on the first axial side L1, relative to the rotating electric machine 2, overlap in a radial view is also possible. That is, the rotor bearing that overlaps with the rotation sensor 7 in a radial view is not limited to the first rotor bearing 81, but may also be the second rotor bearing 82.

[0047] The following is a brief summary of the features of the vehicle drive system (1) described above.

[0048] In one embodiment, the vehicle drive system (1) comprises a rotating electric machine (2), an output member (49) driven and connected to a wheel (10), a power transmission mechanism (5) that transmits driving force between the rotor (21) of the rotating electric machine (2) and the output member (49), and a case (9) that houses the rotating electric machine (2) and the power transmission mechanism (5), wherein the power transmission mechanism (5) comprises a first gear (31) and a second gear (32) arranged on the symmetric axis (A2), and the first The gear (31) and the second gear (32) are rotatably supported by a symmetric bearing (60) relative to the case (9), wherein the direction along the symmetric axis (A2) is defined as the axial direction (L), and the direction perpendicular to the symmetric axis (A2) is defined as the radial direction (R), the symmetric axis (A2) is positioned in a location that overlaps with the rotating electric machine (2) in an axial view along the axial direction (L), and the first gear (31) has a first gear tooth portion (33) that meshes with the teeth of other gears, and the first gear tooth portion (33) is positioned radially The case (9) comprises a first gear support portion (34) that supports from the inside (R1) in the direction (R), and the case (9) comprises a case-side support portion (96) that supports the target bearing (60), and the target bearing (60) comprises a plurality of rolling elements (64), and a target race (66) which is either an outer race (63) that supports the plurality of rolling elements (64) from the outside (R2) in the radial direction (R), or an inner race that supports the plurality of rolling elements (64) from the inside (R1) in the radial direction (R), and a plurality The rolling elements (64) are arranged to roll between a first rolling surface (67) formed on the target race (66) and a second rolling surface (68) formed on the first gear support portion (34) or the case-side support portion (96) so as to be opposite to the first rolling surface (67). The plurality of rolling elements (64) are arranged on the inside (R1) in the radial direction (R) relative to the first gear teeth (33) and overlap with the first gear teeth (33) in a radial view along the radial direction (R).

[0049] With this configuration, if there is a target race (66) which is either an outer race (63) or an inner race that supports multiple rolling elements (64) in the target bearing (60), the other race is unnecessary, making it easier to keep the radial (R) dimension of the target bearing (60) small. Therefore, without increasing the gear diameter of the first gear (31), the multiple rolling elements (64) of the target bearing (60) can be positioned radially (R) inward (R1) relative to the teeth (33) of the first gear, and overlapping with the teeth (33) in a radial view. Furthermore, because the multiple rolling elements (64) are arranged in this way, it is easier to keep the axial (L) dimension of the region on the target axis (A2) where the first gear (31), the second gear (32), and the target bearing (60) are arranged small. By reducing the axial (L) dimension in this way, in configurations like this one, where the symmetric axis (A2) overlaps with the rotating electric machine (2) in an axial view, and the first gear (31), second gear (32), and symmetric bearing (60) are arranged to be aligned with the rotating electric machine (2) in the axial (L) direction, it is easier to reduce the overall axial (L) dimension of the vehicle drive unit (1).

[0050] Furthermore, the vehicle drive unit (1) comprises the first gear support portion (34) having a cylindrical outer cylindrical portion (35) on which the first gear teeth portion (33) is formed on its outer circumferential surface, a cylindrical inner cylindrical portion (37) positioned radially (R) inward (R1) relative to the outer cylindrical portion (35), and a connecting portion (36) connecting the outer cylindrical portion (35) and the inner cylindrical portion (37) in the radial direction (R), wherein the target race (66) is the outer race (63), and the second rolling surface (68) is the inner The symmetric bearing (60) and the case-side support portion (96) are formed on the outer circumferential surface of the side cylindrical portion (37), and are positioned between the outer cylindrical portion (35) and the inner cylindrical portion (37) in the radial direction (R), overlapping with the outer cylindrical portion (35) and the inner cylindrical portion (37) in a radial view. Preferably, the radial distance (d1) between the case-side support portion (96) and the outer cylindrical portion (35) is smaller than the radial thickness (d2) of the outer race (63).

[0051] With this configuration, the inner cylindrical portion (37) of the first gear support portion (34) also functions as the inner race of the target bearing (60), making the inner race of the target bearing (60) unnecessary. Therefore, it is easier to keep the radial (R) dimension of the target bearing (60) small. Also, since the diameter of the circumferential path of the multiple rolling elements (64) is also small, it is easier to keep the number of rolling elements (64) small, making it easier to reduce the cost of the target bearing (60). Furthermore, with this configuration, the radial (R) distance (d1) between the case-side support portion (96) and the outer cylindrical portion (35) is smaller than the radial (R) thickness (d2) of the outer race (63). When the target bearing (60) also has an inner race, the radial (R) thickness of the inner race is often about the same as that of the outer race (63). By eliminating the inner race of the target bearing (60), the expansion of the gear diameter of the first gear (31) can be suppressed while allowing the rolling elements (64) and the teeth portion (33) of the first gear to overlap in a radial view. In other words, with this configuration, the expansion of the gear diameter of the first gear (31) can be suppressed while ensuring the radial (R) thickness of the target bearing (60) and the case-side support portion (96).

[0052] Furthermore, the vehicle drive unit (1) includes a power transmission mechanism (5) which is arranged on the symmetric axis (A2) and includes a connecting shaft (30) that connects the first gear (31) and the second gear (32), with one side of the axial direction (L) being the axial first side (L1) and the other side of the axial direction (L) being the axial second side (L2), the second gear (32) being arranged on the axial second side (L2) relative to the first gear (31), and the connecting shaft (30) being, Preferably, the second gear (32) is integrally formed with the second gear (37) and has an engaging portion (38) that protrudes from the second gear (32) toward the first axial side (L1), the inner cylindrical portion (37) engages with the engaging portion (38) in a state in which relative rotation with respect to the connecting shaft (30) is restricted, and the target bearing (60) and the case-side support portion (96) are arranged toward the first axial side (L1) with respect to the connecting portion (36).

[0053] With this configuration, the target bearing (60) and the case-side support portion (96) are positioned on opposite sides of the axial direction (L) from the second gear (32) with the connecting portion (36) in between. This allows the first gear (31) to be positioned without interfering with the arrangement of the second gear (32) and other gears that mesh with the second gear (32). Furthermore, the first gear support portion (34) that supports the first gear (31) is formed as a separate member from the connecting shaft (30) on which the second gear (32) is integrally formed. Therefore, it is easy to form the second rolling surface (68) on the outer circumferential surface of the inner cylindrical portion (37) of the first gear support member (34) before the first gear support portion (34) and the connecting shaft (30) engage.

[0054] Furthermore, the vehicle drive unit (1) includes a rotation sensor (7) positioned on the rotor axis (A1), which is the rotation axis of the rotor (21), and a rotor bearing (81) that supports a rotor shaft (20) connected to the rotor (21) and rotating integrally with the rotor (21). The case (9) includes a rotor bearing support portion (98) that supports the rotor bearing (81), with the direction perpendicular to the rotor axis (A1) being the rotor axis radial direction (R). The rotor bearing (81) includes a plurality of rotor bearing rolling elements (84) and the plurality of rotor bearing rolling elements (84) are arranged in the rotor axis radial direction. The rotor bearing comprises either an outer rotor bearing race supporting from the outside (R2) in the direction (R) or an inner rotor bearing race (85) supporting a plurality of rotor bearing rolling elements (84) from the inside (R1) in the rotor axial radial direction (R), and without the other of the outer rotor bearing race and the inner rotor bearing race (85), the plurality of rotor bearing rolling elements (84) have a rotor bearing first rolling surface (87) formed on one of the rotor bearing outer race and the inner rotor bearing race (85) that is provided by the rotor bearing (81), and the rotor The rotor bearing (81) and the rotation sensor (7) are arranged to roll between the rotor shaft (20) or the rotor bearing support portion (98) so as to face the first rolling surface (87) of the bearing, and the rotor bearing (81) and the rotation sensor (7) overlap in a view along the rotor shaft radial direction (R), and the power transmission mechanism (5) comprises an input gear (28) arranged on the rotor axis (A1) and connected to the rotor (21) so as to rotate integrally with the rotor (21), and a differential input gear (41), and the driving force transmitted to the differential input gear (41) is transmitted to the The rotating electric machine (2) is equipped with a differential gear mechanism (40) that distributes to a pair of output members (49) which are driven and connected to different wheels (10), wherein the first gear (31) meshes with the input gear (28), and the second gear (32) is connected to the first gear (31) so as to rotate integrally with the first gear (31) and also meshes with the differential input gear (41), and the input gear (28), the first gear (31), the second gear (32), and the differential input gear (41) are arranged on either the axial side (L) with respect to the rotating electric machine (2), and the input gear (28),The first gear (31) and the second gear (32) are preferably positioned in a location that overlaps with the rotating electric machine (2) in the axial view.

[0055] In this configuration, where the gears of the rotating electric machine (2) and the power transmission mechanism (5) are arranged along the axial direction (L), the overall axial dimension of the vehicle drive unit (1) can be easily reduced by keeping the axial dimension (L) of the region where the first gear (31), the second gear (32), and the target bearing (60) are located on the target axis (A2) small. Furthermore, with this configuration, if either the rotor bearing outer race or the rotor bearing inner race (85) (66) is present as a race supporting the multiple rotor bearing rolling elements (84) in the rotor bearing (81), the other race is unnecessary, making it easier to keep the radial dimension (R) of the rotor bearing (81) small. Therefore, without increasing the diameter of the rotation sensor (7), the multiple rotor bearing rolling elements (84) of the rotor bearing (81) can be positioned radially (R) inward (R1) relative to the rotation sensor (7) and overlapping with the rotation sensor (7) in a radial view. Furthermore, because the rotor bearing (81) is arranged in this manner, it is easier to keep the axial (L) dimension of the region on the rotor axis (A1) where the rotor (21), rotation sensor (7), and input gear (28) are arranged small. Thus, it is easier to reduce the axial (L) and radial (R) dimensions of the vehicle drive unit (1). [Explanation of Symbols]

[0056] 1: Vehicle drive unit, 2: Rotating electric machine, 5: Power transmission mechanism, 7: Rotation sensor, 8: Rotor bearing, 9: Case, 10: Wheel, 20: Rotor shaft, 21: Rotor, 28: Input gear, 30: Counter shaft (connecting shaft), 31: First counter gear (first gear), 32: Second counter gear (second gear), 33: First gear teeth, 34: First gear support, 35: Outer cylindrical part, 36: Connecting part, 37: Inner cylindrical part, 38: Engaging part, 40: Differential gear mechanism, 41: Differential input gear, 49: Output member, 60: Target bearing, 63: Outer race, 64: Rotary Dimensions: Moving body, 66: Target race, 67: First rolling surface, 68: Second rolling surface, 81: First rotor bearing (rotor bearing), 84: Rotor bearing rolling element, 85: Rotor bearing inner race, 87: Rotor bearing first rolling surface, 88: Rotor bearing second rolling surface, 96: Case side support part, 98: Rotor bearing support part, A1: First axis (rotor axis), A2: Second axis (target axis), L: Axial direction, L1: First axial side, L2: Second axial side, R: Radial direction, R1: Inner radial side, R2: Outer radial side, d1: Spacing, d2: Thickness

Claims

1. Rotating electric machines and, An output member that is driven and connected to the wheel, A power transmission mechanism that transmits driving force between the rotor of the rotating electric machine and the output member, A vehicle drive system comprising a case housing the aforementioned rotating electric machine and the aforementioned power transmission mechanism, The power transmission mechanism comprises a first gear and a second gear arranged on the axis of the symmetric shaft, and a symmetric bearing that rotatably supports the first gear and the second gear with respect to the case. The direction along the axis of the target is defined as the axial direction, and the direction perpendicular to the axis of the target is defined as the radial direction. The aforementioned target axis is positioned in a location that overlaps with the rotating electric machine in an axial view along the axial direction. The first gear comprises a first gear tooth portion that meshes with the teeth of another gear, and a first gear support portion that supports the first gear tooth portion from the inside in the radial direction. The case includes a case-side support portion that supports the target bearing, The target bearing comprises a plurality of rolling elements and a target race which is either an outer race that supports the plurality of rolling elements from the radially outer side or an inner race that supports the plurality of rolling elements from the radially inner side. The plurality of rolling elements are arranged to roll between a first rolling surface formed in the target race and a second rolling surface formed in the first gear support portion or the case-side support portion so as to be opposite to the first rolling surface. A vehicle drive device in which a plurality of rolling elements are arranged radially inward from the first gear teeth and overlapping with the first gear teeth when viewed radially along the radial direction.

2. The first gear support portion comprises a cylindrical outer cylindrical portion on which the first gear teeth are formed on its outer circumferential surface, a cylindrical inner cylindrical portion positioned radially inward from the outer cylindrical portion, and a connecting portion that connects the outer cylindrical portion and the inner cylindrical portion in the radial direction. The aforementioned race in question is the aforementioned outer race, The second rolling surface is formed on the outer circumferential surface of the inner cylindrical portion, The target bearing and the case-side support are positioned between the outer cylindrical portion and the inner cylindrical portion in the radial direction, at a position that overlaps with the outer cylindrical portion and the inner cylindrical portion when viewed in the radial direction. The vehicle drive device according to claim 1, wherein the radial distance between the case-side support portion and the outer cylindrical portion is smaller than the radial thickness of the outer race.

3. The power transmission mechanism includes a connecting shaft that is positioned on the symmetric axis and connects the first gear and the second gear. One side in the axial direction is designated as the first axial side, and the other side in the axial direction is designated as the second axial side. The second gear is positioned on the second axial side relative to the first gear. The connecting shaft is integrally formed with the second gear and has an engaging portion that protrudes from the second gear toward the first axial direction. The inner cylindrical portion engages with the engaging portion in a state in which its relative rotation with respect to the connecting shaft is restricted. The vehicle drive device according to claim 2, wherein the target bearing and the case-side support portion are arranged on the first axial side with respect to the connecting portion.

4. A rotation sensor is positioned on the rotor axis, which is the rotation axis of the rotor, The rotor includes a rotor bearing that supports a rotor shaft connected to the rotor and rotating integrally with the rotor, The case includes a rotor bearing support portion that supports the rotor bearing, The direction perpendicular to the rotor axis is defined as the rotor axis radial direction, The rotor bearing comprises a plurality of rotor bearing rolling elements, and either a rotor bearing outer race that supports the plurality of rotor bearing rolling elements from the outside in the radial direction of the rotor axis, or a rotor bearing inner race that supports the plurality of rotor bearing rolling elements from the inside in the radial direction of the rotor axis, and without the other of the rotor bearing outer race and the rotor bearing inner race. The plurality of rotor bearing rolling elements are arranged to roll between a first rotor bearing rolling surface formed on one of the rotor bearing's outer and inner races, and a second rotor bearing rolling surface formed on the rotor shaft or rotor bearing support so as to be opposite to the first rotor bearing rolling surface. The rotor bearing and the rotation sensor overlap in a view along the rotor axis radial direction, The power transmission mechanism is An input gear is positioned on the rotor axis and connected to the rotor so as to rotate integrally with the rotor, A differential gear mechanism comprising a differential input gear, which distributes the driving force transmitted to the differential input gear to a pair of output members, each driven and connected to a different wheel, The first gear meshes with the input gear, The second gear is connected to the first gear so as to rotate integrally with the first gear, and also meshes with the differential input gear. The input gear, the first gear, the second gear, and the differential input gear are arranged on either the axial side with respect to the rotating electric machine. The vehicle drive device according to any one of claims 1 to 3, wherein the input gear, the first gear, and the second gear are arranged in a position that overlaps with the rotating electric machine in an axial view.

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