Unit

Abstract

[Problem] To suppress vibration amplification caused by vibration at a planetary gear mechanism and vibration at a motor. [Solution] A unit according to the present invention includes a case, a motor that is housed inside the case, a planetary gear mechanism that is housed inside the case so as to be coaxial with the motor, a first connection part that connects the motor and an inner wall of the case, and a second connection part that connects a ring gear of the planetary gear mechanism and the case. The first connection part and the second connection part do not overlap as seen from the rotational axis direction.

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 by the planetary gear mechanism are transmitted to the outer wall of the case via the connection between the ring gear and the case. Vibrations generated by the motor are also transmitted to the outer wall of the case via the connection between the motor and the case. As a result, vibrations generated by the planetary gear mechanism and vibrations generated by the motor may overlap and be amplified.

[0005] The present invention has been made in view of these technical problems, and has an object to suppress the amplification of vibrations caused by the vibrations generated in the planetary gear mechanism and the vibrations generated in the motor.

[0006] According to one aspect of the present invention, the unit has a case, a motor housed in the case, a planetary gear mechanism housed in the case and arranged coaxially with the motor, a first connection portion connecting the motor to the inner wall of the case, and a second connection portion connecting the ring gear of the planetary gear mechanism to the case, and when viewed from the direction of the rotation axis, the first connection portion and the second connection portion do not overlap.

[0007] In the above aspect, the vibration generating position of the first connecting portion and the vibration generating position of the second connecting portion can be shifted, thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated by the planetary gear mechanism and vibrations generated by the motor.

[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 motor and its periphery as viewed in the direction of arrow II in FIG. 1 . FIG. 3 is a schematic diagram of the planetary gear mechanism and its periphery as viewed in the direction of arrow III in FIG. 1 . FIG. 4 is a diagram for explaining the positional relationship between a first fastening structure connecting the motor and the case and a spline structure connecting the ring gear and the case. FIG. 5 is a diagram for explaining a first modified example of the unit according to the first embodiment. FIG. 6 is a diagram for explaining a second modified example of the unit according to the first embodiment. FIG. 7 is a diagram for explaining a third modified example of the unit according to the first embodiment. FIG. 8 is a skeleton diagram of a unit according to a second embodiment of the present invention. FIG. 9 is a schematic diagram of the planetary gear mechanism and its periphery as viewed in the direction of arrow IX in FIG. 8 , and is a diagram for explaining the positional relationship between the first fastening structure connecting the motor and the case and the second fastening structure connecting the ring gear and the case. FIG. 10 is a diagram for explaining a first aspect of the second fastening structure connecting the ring gear and the case. FIG. 11 is a diagram for explaining a second aspect of the second fastening structure connecting the ring gear and the case. FIG. 12 is a diagram for explaining a third mode of the second fastening structure that connects the ring gear and the case.

[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] Fig. 2 is a schematic diagram of the motor 3 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.

[0021] The unit 100 has a first connection portion that connects the motor 3 to the inner wall of the case 1. That is, the motor 3 is fixed to the inner wall of the case 1 by the first connection portion. In the example shown in Fig. 2, the first connection portion is formed as a first fastening structure 40 that connects the stator 33 to the inner wall of the case 1 via a bolt 9 that serves as a fastening member.

[0022] The "first fastening structure" refers to a protrusion protruding from the outer wall of the stator 33 and / or a protrusion protruding from the inner wall of the case 1, and the stator 33 and the case 1 are connected by inserting a fastening member (e.g., a bolt) into the protrusion.

[0023] In the example shown in FIG. 2 , the first fastening structures 40 are protrusions 41 protruding from the outer wall of the stator 33. The motor 3 (stator 33) and the case 1 are connected by inserting bolts 9 into holes provided in the protrusions 41 and fastening the bolts 9 to internal threads formed in the case 1. In the example shown in FIG. 2 , there are three first fastening structures 40, which are arranged at equal intervals in the circumferential direction. However, the number of first fastening structures 40 can be set as appropriate. Furthermore, the multiple first fastening structures 40 may be arranged at non-equidistant intervals in the circumferential direction.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Fig. 3 is a schematic diagram of the planetary gear mechanism 5 and its surroundings as viewed in the direction of arrow III in Fig. 1. In Fig. 3, some components are omitted for ease of understanding.

[0029] As shown in Fig. 3, 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. 3, the number of mount members 15 is two. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0030] The unit 100 also has a second 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 second connection portion. The second connection portion can be formed as a spline structure 50, for example, as shown in FIG. 3 .

[0031] 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. In the example shown in Fig. 3, there are three spline structures 50, which are arranged at equal intervals in the circumferential direction.

[0032] In the unit 100, vibrations generated in the planetary gear mechanism 5 are transmitted to the outer wall of the case 1 via the second connection portion connecting the ring gear R and the case 1. Vibrations generated in the motor 3 are transmitted to the outer wall of the case 1 via the first connection portion connecting the motor 3 and the case 1. If the vibrations generated in the planetary gear mechanism 5 and the vibrations generated in the motor 3 overlap, the vibrations may be amplified.

[0033] Therefore, as shown in FIG. 4, the unit 100 of this embodiment is configured so that the first fastening structure 40 as the first connecting portion and the spline structure 50 as the second connecting portion do not overlap when viewed from the direction of the rotation axis X.

[0034] FIG. 4 is a diagram for explaining the positional relationship between a first fastening structure 40 as a first connection portion that connects the motor 3 and the case 1 and a spline structure 50 that connects the ring gear R and the case 1.

[0035] As shown in FIG. 4, the planetary gear mechanism 5 is disposed coaxially with the motor 3 .

[0036] The term "coaxial arrangement" refers to an arrangement in which the rotation center of the motor 3 and the rotation center of the planetary gear mechanism 5 coincide with each other.

[0037] In the example shown in Fig. 4, a toothless portion 53 is formed on the outer periphery of the ring gear R as a non-connected portion where the spline structure 50 is not present. The toothless portion 53 overlaps with the first fastening structure 40 when viewed from the direction of the rotation axis X. In other words, the unit 100 is configured so that the first fastening structure 40 and the spline structure 50 do not overlap when viewed from the direction of the rotation axis X. 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 space between adjacent spline teeth 51 in the spline structure 50 is not a toothless portion 53.

[0038] The non-connecting portions (tooth-missing portions 53) can be provided as appropriate in accordance with the positions and number of the first fastening structures 40. In the example shown in Fig. 4, three tooth-missing portions 53 are provided corresponding to the three first fastening structures 40. Therefore, there is no overlap between the multiple first connecting portions and the multiple second connecting portions.

[0039] With the above-described configuration, the unit 100 of this embodiment can shift the vibration generation position of the first connection portion (first fastening structure 40) from the vibration generation position of the second connection portion (spline structure 50), thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated in the planetary gear mechanism 5 and the motor 3.

[0040] When the second connecting portion is formed as the spline structure 50, the above structure can be provided by forming a toothless portion 53 where the spline structure 50 is not provided.

[0041] In the example shown in Figures 3 and 4, the planetary gear mechanism 5 has three pinion gears P, and the arrangement angle α of the toothless portion 53 is less than or equal to the smallest arrangement angle β of the three pinion gears P (see Figure 3).

[0042] 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).

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] Next, a first modification of the unit 100 according to the first embodiment will be described.

[0048] Fig. 5 is a diagram showing a first modified example of the unit 100 according to the first embodiment. Some components are omitted from Fig. 5 for ease of understanding. In the example shown in Fig. 5, three toothless portions 53 are provided corresponding to the three first fastening structures 40. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is four.

[0049] 5, similarly to the examples shown in FIGS. 3 and 4, the first fastening structure 40 and the spline structure 50 do not overlap when viewed from the direction of the rotation axis X.

[0050] 5, the vibration generation position of the first connection portion (first fastening structure 40) can be shifted from the vibration generation position of the second connection portion (spline structure 50), thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated in the planetary gear mechanism 5 and the motor 3.

[0051] In the example shown in FIG. 5, 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.

[0052] 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.

[0053] In addition, in the example shown in Figure 5, 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.

[0054] 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.

[0055] 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.

[0056] Next, a second modification of the unit 100 according to the first embodiment will be described.

[0057] Fig. 6 is a diagram showing a second modified example of the unit 100 according to the first embodiment. Some components are omitted from Fig. 6 for ease of understanding. In the example shown in Fig. 6, two toothless portions 53 are provided corresponding to the two first fastening structures 40. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0058] 6, similarly to the examples shown in FIGS. 3 and 4, the first fastening structure 40 and the spline structure 50 do not overlap when viewed from the direction of the rotation axis X.

[0059] 6, the vibration generation position of the first connection portion (first fastening structure 40) can be shifted from the vibration generation position of the second connection portion (spline structure 50), thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated in the planetary gear mechanism 5 and the motor 3.

[0060] In the example shown in FIG. 6, 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.

[0061] 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.

[0062] Next, a third modification of the unit 100 according to the first embodiment will be described.

[0063] Fig. 7 is a diagram showing a third modified example of the unit 100 according to the first embodiment. Some components are omitted from Fig. 7 to facilitate understanding. In the example shown in Fig. 7, two toothless portions 53 are provided corresponding to the two first fastening structures 40. Furthermore, the number of pinion gears P of the planetary gear mechanism 5 is four.

[0064] 7, similarly to the examples shown in FIGS. 3 and 4, the first fastening structure 40 and the spline structure 50 do not overlap when viewed from the direction of the rotation axis X.

[0065] 7, the vibration generation position of the first connection portion (first fastening structure 40) can be shifted from the vibration generation position of the second connection portion (spline structure 50), thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated in the planetary gear mechanism 5 and the motor 3.

[0066] In the example shown in FIG. 7, 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.

[0067] 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.

[0068] In addition, in the example shown in Figure 7, 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.

[0069] This prevents a pair of pinion gears P from facing multiple toothless portions 53 at the same time, making it possible to suppress a decrease in the support performance of the pinion gears P during revolution.

[0070] Second Embodiment Next, a second embodiment of the present invention will be described.

[0071] Fig. 8 is a skeleton diagram of a unit 200 according to a second embodiment of the present invention. As shown in Fig. 8, in the unit 200 of the second embodiment, a second 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 second 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.

[0072] The "second 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.

[0073] Fig. 9 is a schematic diagram of the periphery of the planetary gear mechanism 5 as viewed in the direction of arrow IX in Fig. 8 , and is a diagram for explaining the positional relationship between the first fastening structure 40 that connects the motor 3 and the case 1 and the second fastening structure 60 that connects the ring gear R and the case 1. Some components are omitted from Fig. 9 for ease of understanding. Fig. 10 is a diagram for explaining a first aspect of the second fastening structure 60. Fig. 11 is a diagram for explaining a second aspect of the second fastening structure 60. Fig. 12 is a diagram for explaining a third aspect of the second fastening structure 60.

[0074] 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. 9, the number of mount members 15 is two. Also, the number of pinion gears P of the planetary gear mechanism 5 is three.

[0075] In the example shown in Fig. 9, the second fastening structure 60 is a protrusion 61 protruding from the outer wall of the ring gear R. The ring gear R and the case 1 are connected by inserting a bolt 16 into a hole provided in the protrusion 61 and fastening the bolt 16 to an internal thread formed in the case 1. In the example shown in Fig. 9, there are three protrusions 61, which are arranged at equal intervals in the circumferential direction. The multiple protrusions 61 (second fastening structures 60) may also be arranged at non-equidistant intervals in the circumferential direction.

[0076] The second fastening structure 60 may be a protrusion 61 protruding from the outer wall of the ring gear R as shown in Figures 9 and 10, or a protrusion 62 protruding from the inner wall of the case 1 as shown in Figure 11, 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 12. In the example shown in Figure 12, the protrusion 64 is internally threaded, but the protrusion 63 may also be internally threaded.

[0077] The unit 200 of this embodiment is configured so that the first fastening structure 40 as the first connecting portion and the second fastening structure 60 as the second connecting portion do not overlap when viewed from the direction of the rotation axis X.

[0078] 9 , a toothless portion 53 is formed on the outer periphery of the ring gear R as a non-connected portion where the second fastening structure 60 is not present. The toothless portion 53 overlaps with the first fastening structure 40 when viewed from the direction of the rotation axis X. In other words, the unit 200 is configured so that the first fastening structure 40 and the second fastening structure 60 do not overlap when viewed from the direction of the rotation axis X.

[0079] The non-connecting portions (tooth-missing portions 53) can be provided as appropriate, taking into consideration the positions and number of the first fastening structures 40. In the example shown in Fig. 9, three tooth-missing portions 53 are provided corresponding to the three first fastening structures 40. Therefore, there is no overlap between the multiple first connecting portions and the multiple second connecting portions.

[0080] With the above-described configuration, the unit 200 of this embodiment can shift the vibration generation position of the first connection portion (first fastening structure 40) from the vibration generation position of the second connection portion (second fastening structure 60), thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated in the planetary gear mechanism 5 and the motor 3.

[0081] When the second connection portion is formed as the second fastening structure 60, the above structure can be provided by forming a toothless portion 53 where the second fastening structure 60 is not provided.

[0082] Furthermore, although not shown, when the second connection portion is formed as the second fastening structure 60, the toothless portion 53 may be arranged so as to overlap with the first fastening structure 40 when viewed from the direction of the rotation axis X, and multiple second fastening structures 60 may be provided without gaps in other regions. In this case as well, there is no overlap between the multiple first connection portions and the multiple second connection portions.

[0083] In this case, similarly to the unit 100 of the first embodiment, by setting the arrangement angle α of the toothless portions 53 to be equal to or less than the smallest arrangement angle β of the multiple pinion gears P, two adjacent pinion gears P will not simultaneously face one toothless portion 53, and it is possible to suppress a decrease in the support performance of the pinion gear P during revolution. The number of pinion gears P may be, for example, three, as in the examples shown in Figures 3 and 4, or four, as in the example shown in Figure 5.

[0084] In this case, if the multiple pinion gears P of the planetary gear mechanism 5 include a pair of pinion gears P that are 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 that are arranged point-symmetrically with respect to the center of rotation of the planetary gear mechanism 5, as in the examples shown in Figures 5 and 7.

[0085] This prevents a pair of pinion gears P from facing multiple toothless portions 53 at the same time, making it possible to suppress a decrease in the support performance of the pinion gears P during revolution.

[0086] The main effects of the units 100 and 200 according to the embodiments of the present invention will be summarized below.

[0087] (1) The units 100 and 200 each have a case 1, a motor 3 housed within the case 1, a planetary gear mechanism 5 housed within the case 1 and arranged coaxially with the motor 3, a first connection portion (first fastening structure 40) connecting the motor 3 to the inner wall of the case 1, and a second connection portion (spline structure 50, second fastening structure 60) connecting the ring gear R of the planetary gear mechanism 5 to the case 1, and the first connection portion and the second connection portion do not overlap when viewed from the direction of the rotation axis X.

[0088] This allows the vibration generation position of the first connection portion to be shifted from the vibration generation position of the second connection portion, thereby reducing the probability of vibration amplification and suppressing vibration amplification due to vibrations generated by the planetary gear mechanism 5 and the motor 3.

[0089] (2) In the unit 100, the second 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, and when viewed from the direction of the rotation axis X, the toothless portion 53 overlaps with the first connection portion (first fastening structure 40).

[0090] When the second connecting 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.

[0091] (3) In the unit 200, the second connection portion is formed as a second fastening structure 60 that connects to the inner wall of the case 1 via the bolt 16, and a toothless portion 53 where the second fastening structure 60 does not exist is formed on the outer periphery of the ring gear R, and when viewed from the direction of the rotation axis X, the toothless portion 53 overlaps with the first connection portion (first fastening structure 40).

[0092] When the second connection portion is formed as the second fastening structure 60, the above structure can be provided by forming a toothless portion 53 where the second fastening structure 60 is not provided.

[0093] (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.

[0094] 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.

[0095] (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.

[0096] 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.

[0097] 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.

[0098] 3 to 7 and 9, 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.

[0099] REFERENCE SIGNS LIST 1 Case 3 Motor 5 Planetary gear mechanism 16 Bolt (fastening member) 40 First fastening structure (first connection portion) 50 Spline structure (second connection portion) 53 Missing tooth portion (non-connection portion) 60 Second fastening structure (second connection portion) 100 Unit 200 Unit P Stepped pinion gear (pinion gear) R Ring gear X Rotation axis α Arrangement angle β Minimum arrangement angle

Claims

1. A unit having: a case; a motor housed within the case; a planetary gear mechanism housed within the case and arranged coaxially with the motor; a first connection portion connecting the motor to an inner wall of the case; and a second connection portion connecting a ring gear of the planetary gear mechanism to the case, wherein the first connection portion and the second connection portion do not overlap when viewed in the direction of the rotation axis.

2. A unit as claimed in claim 1, wherein the second 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 in the direction of the rotation axis, the non-connection portion overlaps with the first connection portion.

3. A unit as claimed in claim 1, wherein the second 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 in the direction of the rotation axis, the non-connection portion overlaps with the first connection portion.

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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