Unit

Abstract

[Problem] To reduce the influence of a planetary gear mechanism on vehicle vibration. [Solution] A unit comprising: a case; a planetary gear mechanism accommodated in the case; a mount member that is provided on an outer wall of the case and connects the case and a vehicle body; and a connection part that connects a ring gear of the planetary gear mechanism and an inner wall of the case, wherein, when viewed from a rotation axis direction, the connection part is not disposed between a rotation center of the planetary gear mechanism and the entire area of a boundary part between the mount member and the case.

Description

unit

[0001] The present invention relates to a unit.

[0002] Patent Documents 1 and 2 disclose drive units for electric vehicles that have planetary gear mechanisms.

[0003] International Publication No. 2021 / 137281 Japanese Patent Application Laid-Open No. 2011-252532

[0004] Vibrations generated in the planetary gear mechanism are transmitted to the outer wall of the case via the connection between the ring gear and the case. The vibrations transmitted to the outer wall of the case are then transmitted to the vehicle body via the boundary between the case and the mount member. The shorter the vibration transmission distance between the connection between the ring gear and the case and the mount member, the greater the impact of the planetary gear mechanism on vehicle vibrations.

[0005] The present invention has been made in view of these technical problems, and has an object to reduce the influence of the planetary gear mechanism on vehicle vibrations.

[0006] According to one aspect of the present invention, the unit has a case, a planetary gear mechanism housed within the case, a mounting member provided on the outer wall of the case and connecting the case to the vehicle body, and a connection portion connecting the ring gear of the planetary gear mechanism to the inner wall of the case, and when viewed from the direction of the rotation axis, the connection portion is not located between the center of rotation of the planetary gear mechanism and the entire area of ​​the boundary between the mounting member and the case.

[0007] In the above-described aspect, the connecting portion is not located at the position on the ring gear closest to the mount member, which increases the distance over which vibrations are transmitted from the connecting portion to the mount member, thereby reducing the impact of the planetary gear mechanism on vehicle vibrations.

[0008] FIG. 1 is a skeleton diagram of a unit according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of the periphery of a planetary gear mechanism as viewed in the direction of arrow II in FIG. 1. FIG. 3 is a diagram showing a spline structure connecting a ring gear and a case. FIG. 4 is a diagram showing a modified example of the unit according to the first embodiment. FIG. 5 is a skeleton diagram of a unit according to a second embodiment of the present invention. FIG. 6 is a schematic diagram of the periphery of the planetary gear mechanism as viewed in the direction of arrow VI in FIG. 5, showing a fastening structure connecting the ring gear and a case. FIG. 7 is a diagram for explaining a first mode of the fastening structure. FIG. 8 is a diagram for explaining a second mode of the fastening structure. FIG. 9 is a diagram for explaining a third mode of the fastening structure. FIG. 10 is a diagram showing a modified example of the unit according to the second embodiment.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification, the same elements are designated by the same reference numerals throughout.

[0010] First Embodiment FIG. 1 is a skeleton diagram of a unit 100 according to a first embodiment of the present invention.

[0011] As shown in FIG. 1, the unit 100 includes a case 1, an inverter 2, a motor 3, a planetary gear mechanism 5 that reduces the output rotation of the motor 3 and inputs it to a differential mechanism 4, and drive shafts D1 and D2 as drive shafts.

[0012] In the unit 100, a planetary gear mechanism 5, a differential mechanism 4, and drive shafts D1 and D2 are provided along a transmission path of the output rotation around the rotation axis X of the motor 3. The rotation center of the motor 3, the planetary gear mechanism 5, the differential mechanism 4, and the drive shafts D1 and D2 is the rotation axis X.

[0013] In unit 100, the output rotation of motor 3 is decelerated by planetary gear mechanism 5 and input to differential mechanism 4, and then transmitted via drive shafts D1 and D2 to the left and right drive wheels W of the vehicle on which unit 100 is mounted.

[0014] The case 1 is made up of one or more members and houses therein an inverter 2, a motor 3, and power transmission mechanisms such as a differential mechanism 4 and a planetary gear mechanism 5. The case 1 is fixed to the vehicle so as not to be rotatable.

[0015] The inverter 2 includes an inverter housing chamber provided on the outer wall side of the case 1 and a circuit section housed in the inverter housing chamber. When viewed in the radial direction, the inverter 2 (the inverter housing chamber and the circuit section) overlaps with the motor 3, the differential mechanism 4, the planetary gear mechanism 5, and motor bearings 7 and 8 that support the motor shaft 31 of the motor 3.

[0016] "Element A and element B overlap when viewed in a predetermined direction" refers to a state in which element A and element B are aligned in a predetermined direction (axial direction, radial direction, gravity direction, etc.) and at least partially overlap when observed from the predetermined direction. "Element A and element B overlap when viewed in a predetermined direction" is synonymous with "element A and element B overlap in a predetermined direction."

[0017] In contrast, "element A and element B do not overlap when viewed in a predetermined direction" refers to a state in which element A and element B are not lined up in a predetermined direction (axial direction, radial direction, gravity direction, vehicle running direction, etc.), and there is no overlapping portion between element A and element B when observed from the predetermined direction. "element A and element B do not overlap when viewed in a predetermined direction" is synonymous with "element A and element B do not overlap in a predetermined direction."

[0018] The motor 3 is housed in a motor housing chamber 11 formed inside the case 1. The motor 3 is electrically connected to a battery (not shown) outside the unit 100 via the inverter 2, and functions as an electric motor by receiving power from the battery. The motor 3 can also function as a generator.

[0019] The motor 3 has a rotor 32 and a stator 33. The rotor 32 has a motor shaft 31. The rotor 32 is supported by the case 1 via motor bearings 7 and 8. The stator 33 is fastened to the inner wall of the motor housing chamber 11 by a plurality of bolts 9.

[0020] The motor bearing 8 is supported by a bearing retainer 10. The bearing retainer 10 is fastened to the inner wall of the motor housing chamber 11 by a plurality of bolts 12. The bearing retainer 10 is also applicable to the motor bearing 7. The bearing retainer 10 may be applied to either the motor bearing 7 or 8, or to both.

[0021] The planetary gear mechanism 5 is a stepped pinion planetary gear mechanism having a sun gear S, a plurality of stepped pinion gears (hereinafter simply referred to as pinion gears) P, a carrier C that rotatably supports the plurality of pinion gears P, and a ring gear R.

[0022] The sun gear S meshes with a plurality of pinion gears P (large pinions), and the plurality of pinion gears P (small pinions) mesh with a ring gear R. The number of pinion gears P is set appropriately. The planetary gear mechanism 5 may be a stepped pinion planetary gear mechanism, a single pinion planetary gear mechanism, or a double pinion planetary gear mechanism.

[0023] The sun gear S is connected to the motor shaft 31. The ring gear R is fixed to the case 1. The carrier C is connected to the differential mechanism 4. The carrier C is supported by the case 1 via carrier bearings 13 and 14.

[0024] Fig. 2 is a schematic diagram of the planetary gear mechanism 5 and its surroundings as viewed in the direction of arrow II in Fig. 1. In Fig. 2, some components are omitted for ease of understanding.

[0025] As shown in Fig. 2, the unit 100 has a plurality of mount members 15 provided on the outer wall of the case 1. The plurality of mount members 15 connect the case 1 to the vehicle body 300. The number of the plurality of mount members 15 is set appropriately. In the example shown in Fig. 2, the number of mount members 15 is two. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0026] 2, the unit 100 has a connection portion that connects the ring gear R of the planetary gear mechanism 5 to the inner wall of the case 1. That is, the ring gear R is fixed to the inner wall of the case 1 by the connection portion. The connection portion can be formed as a spline structure 50, for example, as shown in FIG.

[0027] FIG. 3 is a diagram showing a spline structure 50 as a connection portion that connects the ring gear R and the case 1. Some components are omitted from FIG. 3 to facilitate understanding. The example shown in FIG. 3 differs from the example shown in FIG. 2 in that the spline structure 50 as a connection portion is shown, but is otherwise the same as the example shown in FIG. 2. In the example shown in FIG. 3, the number of mount members 15 is two. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0028] As shown in FIG. 3 , the spline structure 50 has a plurality of spline teeth 51 formed on the outer periphery of the ring gear R and a plurality of spline grooves 52 formed on the inner wall of the case 1 .

[0029] In the unit 100, vibrations generated in the planetary gear mechanism 5 are transmitted to the outer wall of the case 1 via the connection between the ring gear R and the case 1. The vibrations transmitted to the outer wall of the case 1 are then transmitted to the vehicle body 300 via the boundary between the case 1 and the mount member 15. The shorter the vibration transmission distance between the connection between the ring gear R and the case 1 and the mount member 15, the greater the influence of the planetary gear mechanism 5 on vehicle vibrations.

[0030] Therefore, in the example shown in FIG. 3 , when viewed from the direction of the rotation axis X, the spline structure 50 as a connection portion is not disposed between the rotation center (rotation axis X) of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1.

[0031] In other words, a toothless portion 53 is formed on the outer periphery of the ring gear R as a non-connecting portion where the spline structure 50 does not exist, and when viewed from the direction of the rotation axis X, the toothless portion 53 is located between the rotation center of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1 (see the two-dot chain line). In other words, when the mount member 15 and the ring gear R overlap in the radial direction, when the outer periphery in the radial direction is viewed from the rotation center of the planetary gear mechanism 5, the entire boundary between the mount member 15 and the case 1 does not overlap with the connecting portion. Note that the spacing (circumferential length) between adjacent spline teeth 51 in the spline structure 50 is smaller than the circumferential length of the toothless portion 53. In other words, the toothless portion 53 does not exist between adjacent spline teeth 51 in the spline structure 50.

[0032] The non-connecting portions (tooth-missing portions 53) can be provided as appropriate, taking into consideration the positions and number of the mount members 15. In the example shown in Figure 3, two tooth-missing portions 53 are provided corresponding to the two mount members 15.

[0033] Vibrations generated at the connection portion of the ring gear R are transmitted to the outer wall of the case 1. In contrast, in the example shown in Fig. 3, no connection portion is located at the position on the ring gear R closest to the mount member 15. This makes it possible to increase the distance over which vibrations are transmitted from the connection portion to the mount member 15. This reduces the impact of the planetary gear mechanism 5 on vehicle vibrations.

[0034] When the connection portion is formed as a spline structure 50, the above structure can be provided by forming a toothless portion 53 where no spline structure 50 is provided.

[0035] In the example shown in FIG. 3, the planetary gear mechanism 5 has three pinion gears P, and the arrangement angle α of the toothless portion 53 is equal to or smaller than the smallest arrangement angle β of the three pinion gears P.

[0036] The "arrangement angle of the toothless portion 53" refers to the angle of the apex of the triangle formed by connecting the rotation center of the planetary gear mechanism 5 and the two boundary points between the toothless portion 53 and the spline structure 50 (both circumferential ends of the toothless portion 53).

[0037] The "arrangement angle of the pinion gear P" means the angle of the vertex of the triangle formed by connecting the center of rotation of the planetary gear mechanism 5, the vertex of the meshing between one pinion gear P and the ring gear R, and the vertex of the meshing between another pinion gear P adjacent to the one pinion gear P and the ring gear R, with the center of rotation as the vertex.

[0038] The "minimum arrangement angle of the pinion gear P" means that when multiple pinion gears P are arranged at equal intervals, the arrangement angles of adjacent pinion gears P are all the same and can be evaluated as the minimum. When multiple pinion gears P are arranged at non-equidistant intervals, the "minimum arrangement angle of the pinion gear P" means the smallest arrangement angle of adjacent pinion gears P.

[0039] Comparing the case where the pinion gear P is positioned facing the toothless portion 53 with the case where the pinion gear P is positioned facing the spline structure 50 during the revolution of the pinion gear P, the pinion gear P has higher support performance when it is positioned facing the spline structure 50. Therefore, it is preferable that as many of the pinion gear P as possible be positioned facing the spline structure 50 during the revolution of the pinion gear P.

[0040] Therefore, by setting the arrangement angles α and β as described above, two adjacent pinion gears P will not face one missing tooth portion 53 at the same time, and it is possible to suppress a decrease in the support performance of the pinion gear P during revolution.

[0041] Next, a modified example of the unit 100 according to the first embodiment will be described.

[0042] Fig. 4 is a diagram showing a modified example of the unit 100 according to the first embodiment. Some components are omitted from Fig. 4 to facilitate understanding. In the example shown in Fig. 4, the number of mount members 15 is two. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is four.

[0043] In the example shown in Fig. 3, the two mount members 15 are arranged in point symmetry with respect to the center of rotation of the planetary gear mechanism 5. On the other hand, in the example shown in Fig. 4, the two mount members 15 are not arranged in point symmetry with respect to the center of rotation of the planetary gear mechanism 5. Therefore, in the example shown in Fig. 4, the arrangement of the multiple non-connected portions (tooth-missing portions 53) differs from the example shown in Fig. 3.

[0044] 4, similarly to the example shown in Fig. 3, when viewed from the direction of rotation axis X, a missing tooth portion 53 is disposed between the rotation center of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1 (see the two-dot chain line). That is, in the example shown in Fig. 4, two missing tooth portions 53 are provided corresponding to the two mount members 15.

[0045] 4, the connecting portion is not located at the position on the ring gear R closest to the mount member 15. This increases the distance over which vibrations are transmitted from the connecting portion to the mount member 15. This reduces the effect of the planetary gear mechanism 5 on vehicle vibrations.

[0046] In the example shown in FIG. 4, the planetary gear mechanism 5 has four pinion gears P, and the arrangement angle α of the toothless portion 53 is equal to or smaller than the smallest arrangement angle β of the four pinion gears P.

[0047] Therefore, two adjacent pinion gears P do not face one toothless portion 53 at the same time, and a decrease in the support performance of the pinion gears P during revolution can be suppressed.

[0048] In addition, in the example shown in Figure 4, the four pinion gears P include a pair of pinion gears P arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5, and the multiple missing tooth portions 53 do not include a pair of missing tooth portions 53 arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5.

[0049] Comparing the case where the pinion gear P is positioned facing the toothless portion 53 with the case where the pinion gear P is positioned facing the spline structure 50 during the revolution of the pinion gear P, the pinion gear P has higher support performance when it is positioned facing the spline structure 50. Therefore, it is preferable that as many of the pinion gear P as possible be positioned facing the spline structure 50 during the revolution of the pinion gear P.

[0050] Therefore, when the planetary gear mechanism 5 includes a pair of pinion gears P arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5, breaking the symmetry of the arrangement of the multiple tooth-missing portions 53 prevents the pair of pinion gears P from facing multiple tooth-missing portions 53 at the same time, thereby making it possible to suppress a decrease in the support performance of the pinion gears P during revolution.

[0051] Second Embodiment Next, a second embodiment of the present invention will be described.

[0052] Fig. 5 is a skeleton diagram of a unit 200 according to a second embodiment of the present invention. As shown in Fig. 5, in the unit 200 of the second embodiment, the connection portion that connects the ring gear R of the planetary gear mechanism 5 to the inner wall of the case 1 is formed as a fastening structure 60 that connects the ring gear R to the inner wall of the case 1 via a bolt 16 as a fastening member. The other configurations are the same as those of the unit 100 of the first embodiment.

[0053] The "fastening structure" refers to a protrusion protruding from the outer wall of the ring gear R and / or a protrusion protruding from the inner wall of the case 1, and the ring gear R and the case 1 are connected by inserting a fastening member (e.g., a bolt) into the protrusion.

[0054] Fig. 6 is a schematic diagram of the periphery of the planetary gear mechanism 5 as viewed in the direction of arrow VI in Fig. 5, and shows a fastening structure 60 that connects the ring gear R and the case 1. Some components are omitted from Fig. 6 to facilitate understanding. Fig. 7 is a diagram for explaining a first embodiment of the fastening structure 60. Fig. 8 is a diagram for explaining a second embodiment of the fastening structure 60. Fig. 9 is a diagram for explaining a third embodiment of the fastening structure 60.

[0055] In the unit 200, the number of mount members 15 and the number of pinion gears P are set appropriately. In the example shown in Fig. 6, the number of mount members 15 is two. Also, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0056] 6 , the fastening structure 60 is four protrusions 61 protruding from the outer wall of the ring gear R. The ring gear R and the case 1 are connected by inserting bolts 16 into holes provided in the protrusions 61 and fastening the bolts 16 to internal threads formed in the case 1.

[0057] The fastening structure 60 may be a protrusion 61 protruding from the outer wall of the ring gear R as shown in Figures 6 and 7, or a protrusion 62 protruding from the inner wall of the case 1 as shown in Figure 8, or a protrusion 64 protruding from the inner wall of the case 1 and a protrusion 63 protruding from the outer wall of the ring gear R as shown in Figure 9. In the example shown in Figure 9, the protrusion 64 is internally threaded, but the protrusion 63 may also be internally threaded.

[0058] In the example shown in FIG. 6 , when viewed from the direction of the rotation axis X, the fastening structure 60 as a connection portion is not disposed between the rotation center of the planetary gear mechanism 5 and the entire boundary area between the mount member 15 and the case 1 (see the two-dot chain line).

[0059] That is, a toothless portion 53 is formed on the outer periphery of the ring gear R as a non-connected portion where no fastening structure 60 exists, and when viewed from the direction of the rotation axis X, the toothless portion 53 is disposed between the rotation center of the planetary gear mechanism 5 and the entire area of ​​the boundary between the mount member 15 and the case 1. In other words, when the mount member 15 and the ring gear R overlap in the radial direction, when the outer periphery in the radial direction is viewed from the rotation center of the planetary gear mechanism 5, the entire area of ​​the boundary between the mount member 15 and the case 1 does not overlap with the connected portion.

[0060] The non-connecting portions (tooth-missing portions 53) can be provided as appropriate, taking into consideration the positions and number of the mount members 15. In the example shown in Fig. 6, four tooth-missing portions 53 are provided, including two tooth-missing portions 53 provided at positions corresponding to the two mount members 15.

[0061] 6, no connecting portion is located at the position on the ring gear R closest to the mount member 15. This increases the distance over which vibrations are transmitted from the connecting portion to the mount member 15. This reduces the impact of the planetary gear mechanism 5 on vehicle vibrations.

[0062] When the connection portion is formed as the fastening structure 60, the above structure can be provided by forming the toothless portion 53 where the fastening structure 60 is not provided.

[0063] Next, a modified example of the unit 200 according to the second embodiment will be described.

[0064] Fig. 10 is a diagram showing a modified example of the unit 200 according to the second embodiment. Some components are omitted from Fig. 10 to facilitate understanding. In the example shown in Fig. 10, the number of mount members 15 is two. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0065] When the connection portion is formed as a fastening structure 60, as shown in FIG. 10 , when viewed from the direction of the rotation axis X, a toothless portion 53 serving as a non-connection portion where no fastening structure 60 is provided may be disposed between the rotation center of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1 (see the two-dot chain line), and multiple fastening structures 60 may be provided without gaps in other regions.

[0066] 10, two toothless portions 53 are provided corresponding to the two mount members 15. In other words, no connecting portion is located at the position on the ring gear R closest to the mount member 15. This increases the distance over which vibration is transmitted from the connecting portion to the mount member 15. This reduces the impact of the planetary gear mechanism 5 on vehicle vibration.

[0067] In the example shown in FIG. 10, the planetary gear mechanism 5 has three pinion gears P, and the arrangement angle α of the toothless portion 53 is equal to or smaller than the smallest arrangement angle β of the three pinion gears P.

[0068] This prevents two adjacent pinion gears P from facing one toothless portion 53 at the same time, and reduces the deterioration of the support performance of the pinion gears P during revolution.

[0069] Furthermore, although not shown, as in the example shown in FIG. 4 , when the two mount members 15 are not arranged in point symmetry with respect to the rotation center of the planetary gear mechanism 5, the toothless portion 53 may be arranged between the rotation center of the planetary gear mechanism 5 and the entire boundary between the mount members 15 and the case 1 (see the two-dot chain line) when viewed from the direction of the rotation axis X, and the fastening structure 60 may be provided in other regions without any gaps.

[0070] Furthermore, if the multiple pinion gears P of the planetary gear mechanism 5 include a pair of pinion gears P arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5, the multiple tooth-missing portions 53 may not include a pair of tooth-missing portions 53 arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5.

[0071] This makes it possible to suppress a decrease in the support performance of the pinion gear P during revolution.

[0072] The main effects of the units 100 and 200 according to the embodiments of the present invention will be summarized below.

[0073] (1) The units 100 and 200 each include a case 1, a planetary gear mechanism 5 housed within the case 1, a mount member 15 provided on the outer wall of the case 1 and connecting the case 1 to the vehicle body 300, and a connection portion (spline structure 50, fastening structure 60) connecting the ring gear R of the planetary gear mechanism 5 to the inner wall of the case 1. When viewed from the direction of the rotation axis X, no connection portion is located between the center of rotation (rotation axis X) of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1.

[0074] According to this, no connecting portion is located at the position on the ring gear R closest to the mount member 15. This makes it possible to increase the distance over which vibration is transmitted from the connecting portion to the mount member 15. This reduces the effect of the planetary gear mechanism 5 on vehicle vibration.

[0075] (2) In the unit 100, the connection portion is formed as a spline structure 50 that meshes with the inner wall of the case 1, and a toothless portion 53 where the spline structure 50 does not exist is formed on the outer periphery of the ring gear R. When viewed from the direction of the rotation axis X, the toothless portion 53 is disposed between the rotation center (rotation axis X) of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1.

[0076] When the connection portion is formed as a spline structure 50, the above structure can be provided by forming a toothless portion 53 where no spline structure 50 is provided.

[0077] (3) In the unit 200, the connection portion is formed as a fastening structure 60 that connects to the inner wall of the case 1 via the bolt 16, and a toothless portion 53 where the fastening structure 60 does not exist is formed on the outer periphery of the ring gear R. When viewed from the direction of the rotation axis X, the toothless portion 53 is disposed between the rotation center (rotation axis X) of the planetary gear mechanism 5 and the entire boundary between the mount member 15 and the case 1.

[0078] When the connection portion is formed as the fastening structure 60, the above structure can be provided by forming the toothless portion 53 where the fastening structure 60 is not provided.

[0079] (4) The planetary gear mechanism 5 has a plurality of pinion gears P that mesh with the ring gear R, and the arrangement angle α of the toothless portion 53 is equal to or smaller than the smallest arrangement angle β of the plurality of pinion gears P.

[0080] This prevents two adjacent pinion gears P from facing one toothless portion 53 at the same time, and reduces the deterioration of the support performance of the pinion gears P during revolution.

[0081] (5) The units 100, 200 have a plurality of missing tooth portions 53, the planetary gear mechanism 5 has a plurality of pinion gears P that mesh with the ring gear R, the plurality of pinion gears P include a pair of pinion gears P that are arranged point-symmetrically with respect to the rotation center (rotation axis X) of the planetary gear mechanism 5, and the plurality of missing tooth portions 53 do not include a pair of missing tooth portions 53 that are arranged point-symmetrically with respect to the rotation center (rotation axis X) of the planetary gear mechanism 5.

[0082] When multiple planetary gear mechanisms 5 include a pair of pinion gears P arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5, breaking the symmetry of the arrangement of the multiple tooth-missing portions 53 prevents the pair of pinion gears P from facing multiple tooth-missing portions 53 at the same time, making it possible to suppress a decrease in the support performance of the pinion gear P during revolution.

[0083] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0084] 2 to 4, 6, and 10, the pinion gears P are arranged at equal intervals in the circumferential direction. However, the pinion gears P may be arranged at non-equidistant intervals in the circumferential direction.

[0085] REFERENCE SIGNS LIST 1 Case 5 Planetary gear mechanism 15 Mounting member 16 Bolt (fastening member) 50 Spline structure (connection portion) 53 Missing tooth portion (non-connection portion) 60 Fastening structure (connection portion) 100 Unit 200 Unit 300 Vehicle body P Stepped pinion gear (pinion gear) R Ring gear X Rotation axis (center of rotation) α Arrangement angle β Minimum arrangement angle

Claims

1. A unit having: a case; a planetary gear mechanism housed within said case; a mount member provided on the outer wall of said case and connecting said case to a vehicle body; and a connection portion connecting a ring gear of said planetary gear mechanism to the inner wall of said case; wherein, when viewed from the direction of the rotation axis, said connection portion is not located between the center of rotation of said planetary gear mechanism and the entire area of ​​the boundary portion between said mount member and said case.

2. A unit as claimed in claim 1, wherein the connection portion is formed as a spline structure that meshes with the inner wall of the case, and a non-connection portion where the spline structure is not present is formed on the outer periphery of the ring gear, and when viewed from the direction of the rotation axis, the non-connection portion is located between the center of rotation of the planetary gear mechanism and the entire area of ​​the boundary portion between the mount member and the case.

3. A unit as claimed in claim 1, wherein the connection portion is formed as a fastening structure that connects to the inner wall of the case via a fastening member, and a non-connection portion where the fastening structure is not present is formed on the outer periphery of the ring gear, and when viewed from the direction of the rotation axis, the non-connection portion is located between the center of rotation of the planetary gear mechanism and the entire area of ​​the boundary portion between the mount member and the case.

4. A unit according to claim 2 or 3, wherein the planetary gear mechanism has a plurality of pinion gears that mesh with the ring gear, and the arrangement angle of the non-connected portion is equal to or less than the smallest arrangement angle of the plurality of pinion gears.

5. A unit as claimed in claim 2 or claim 3, comprising a plurality of said non-connecting parts, wherein said planetary gear mechanism comprises a plurality of pinion gears that mesh with said ring gear, said plurality of pinion gears including a pair of said pinion gears that are arranged point symmetrically with respect to the center of rotation of said planetary gear mechanism, and said plurality of non-connecting parts does not include a pair of said non-connecting parts that are arranged point symmetrically with respect to the center of rotation of said planetary gear mechanism.

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