Electric vehicle

Abstract

The invention provides an electric vehicle capable of suppressing NV. A motor-side end face of a large-diameter portion formed between a spline-fitted portion formed in the gear shaft and the first gear is in contact with a first-gear-side end face of an inner ring of the second bearing. In addition, a gap between a third-bearing-side end surface of a step portion formed adjacent to a third-bearing-side end portion of the rotor shaft and a motor-side end surface of the third bearing is larger than an internal gap of the second bearing. Thus, when thrust acting on the gear shaft in the motor direction is generated, the internal clearance of the second bearing is reduced earlier than the clearance between the end face of the step portion on the third bearing side and the end face of the third bearing on the motor side. Therefore, thrust is transmitted to the second housing via the second bearing, and radiation sound is suppressed.

Description

Technical Field

[0001] The present invention relates to an electric vehicle including a motor and one of helical gears on the same rotation axis. Background Art

[0002] As is known, there is an electric vehicle, which includes: an electric motor; a helical gear, which is formed by meshing a first gear arranged on the rotation axis of the electric motor with a second gear arranged on another rotation axis parallel to the rotation axis of the electric motor; a gear shaft, the outer peripheral surface of the gear shaft on the motor side is connected to the inner peripheral surface of the first gear side of the rotor shaft of the electric motor by spline engagement, and the gear shaft fixes the first gear so that it cannot rotate relatively; a housing, the housing having a first housing and a second housing, the first housing and the second housing are engaged to form a gear chamber for accommodating the helical gear, and the second housing is used to form a motor chamber for accommodating the electric motor; a first bearing, the first bearing supports the gear shaft in a rotatable manner on the first housing at the end of the gear shaft on the side opposite to the motor side; and a second bearing, the second bearing supports the rotor shaft in a rotatable manner on the second housing at the end of the rotor shaft on the first gear side. For example, the motor drive device described in Patent Document 1 has such a structure. Patent Document 1 discloses that a thrust force in the direction of the motor generated on the gear shaft by the gear meshing reaction force in the helical gear acts on the inner ring of the second bearing, and the thrust acting on the inner ring acts on the second housing via the outer ring of the second bearing.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-175261

[0006] Here, there is sometimes a third housing that forms a motor chamber by joining with the second housing, and the rotor shaft is rotatably supported on the third housing via a third bearing at the end of the rotor shaft on the side opposite to the first gear side. In this case, for example, the thrust transmitted to the rotor shaft directly from the gear shaft or indirectly via the second bearing may be transmitted to the third housing via the third bearing. In this case, the rotor shaft may hit the third housing via the third bearing due to the thrust, and NV may deteriorate. "NV" is a general term for noise and vibration generated in a vehicle, and means at least one of the noise and vibration in the vehicle. Summary of the invention

[0007] Problems to be solved by the invention

[0008] The present invention has been made under the above circumstances, and an object of the present invention is to provide an electric vehicle capable of suppressing NV.

[0009] Means for solving problems

[0010] The gist of the first invention is an electric vehicle comprising: (a) an electric motor; a helical gear, the helical gear being formed by meshing a first gear arranged on a rotation axis of the electric motor with a second gear arranged on another rotation axis parallel to the rotation axis of the electric motor; a gear shaft, the outer peripheral surface of the gear shaft on the motor side being connected to the inner peripheral surface of the first gear side of the rotor shaft of the electric motor by spline engagement, the gear shaft fixing the first gear so as to be non-rotatable relative to the first gear; a housing, the housing having a first housing, a second housing and a third housing, the first housing and the second housing being joined to form a gear chamber for accommodating the helical gear, and the second housing and the third housing being joined to form a motor chamber for accommodating the electric motor; and a first bearing, the first bearing rotatably supporting the gear shaft at the end of the gear shaft on the side opposite to the motor side to the first bearing. A housing; a second bearing, the second bearing supporting the rotor shaft rotatably on the second housing at an end of the rotor shaft on the first gear side; and a third bearing supporting the rotor shaft rotatably on the third housing at an end of the rotor shaft on the side opposite to the first gear side, wherein (b) the gear shaft has a large diameter portion formed between the spline-engaged portion and the first gear and having a larger diameter than the spline-engaged portion, (c) the rotor shaft has a step portion formed adjacent to the end on the third bearing side and having a larger diameter than the end on the third bearing side, (d) the end surface of the large diameter portion on the motor side abuts against the end surface of the inner ring of the second bearing on the first gear side, and (e) the gap between the end surface of the third bearing side of the step portion and the end surface of the third bearing on the motor side is larger than the internal gap of the second bearing.

[0011] Effects of the Invention

[0012] According to the first invention, the end face of the motor side of the large diameter portion formed between the spline-engaged portion of the gear shaft and the first gear and having a larger diameter than the spline-engaged portion abuts against the end face of the first gear side of the inner ring of the second bearing. In addition, the gap between the end face of the third bearing side of the step portion formed adjacent to the end of the third bearing side of the rotor shaft and having a larger diameter than the end of the third bearing side and the end face of the motor side of the third bearing is larger than the internal gap of the second bearing. Thus, in the case where a thrust acting on the gear shaft in the direction of the motor is generated due to the gear meshing reaction force in the helical gear, the thrust acts on the inner ring of the second bearing. At this time, the internal gap of the second bearing, that is, the clearance between the inner ring and the outer ring is reduced first compared with the gap between the end face of the third bearing side of the step portion and the end face of the motor side of the third bearing. Therefore, the thrust acting on the gear shaft in the direction of the motor is transmitted to the second housing via the second bearing and received by the second housing, and is not easily transmitted to the third housing, and the third housing is not easily a sounding portion. Since the second housing is located between the gear chamber and the motor chamber, even if thrust is transmitted to the second housing, the radiated sound to the outside of the housing can be suppressed. Therefore, NV can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a diagram for explaining an example of a schematic structure of an electric vehicle to which the present invention is applied.

[0014] Figure 2 (a) is a diagram for explaining an example of a schematic configuration of a drive device, and is a perspective view of the electric vehicle as seen from the front and left side. Figure 2 (b) is a diagram for explaining an example of a schematic configuration of a drive device, and is a side view seen from the left side of the electric vehicle.

[0015] Figure 3 (a) is a cross-sectional view illustrating an example of a structure in which a rotor shaft and a reduction shaft in a comparative example are supported by a housing. Figure 3 (b) means Figure 3 (a) is a diagram showing an example of the transmission method of load and radiated sound.

[0016] Figure 3 (c) is a cross-sectional view illustrating an example of a structure in which the rotor shaft and the reduction shaft in the present embodiment are supported by the casing. Figure 3 (d) is Figure 3 A partial enlarged view of (c). Figure 3 The (e) is Figure 3 (c) is a diagram showing an example of the transmission method of load and radiated sound.

[0017] Description of Reference Numerals

[0018] 10: Electric vehicles

[0019] 18: Shell

[0020] 18a: Shell (first shell)

[0021] 18b: Shell body (second shell)

[0022] 18b1: Next door (second housing)

[0023] 18c: Cover (third shell)

[0024] 28: Driven gear (second gear)

[0025] 36: Reduction gear (first gear)

[0026] 37: Reduction shaft (gear shaft)

[0027] 37a: Large diameter part

[0028] 39: Helical gear

[0029] BR1: First bearing

[0030] BR2: Second bearing

[0031] BR2i: Inner Circle

[0032] BR3: Third bearing

[0033] CL2: Second axis (another rotation axis parallel to the rotation axis of the motor)

[0034] CL3: Third axis (rotation axis of the motor)

[0035] MG2: Second motor (electric motor)

[0036] RSmg2: rotor shaft (rotor shaft of the motor)

[0037] RSa: Step

[0038] Rg: gear room

[0039] Rm: Motor room DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0041] [Example]

[0042] Figure 1 FIG. 1 is a diagram for explaining an example of a schematic structure of an electric vehicle 10 to which the present invention is applied. Figure 1, the electric vehicle 10 is a hybrid vehicle including an engine 12, a first electric motor MG1, and a second electric motor MG2. In addition, the electric vehicle 10 includes drive wheels 14 and a power transmission device 16. The power transmission device 16 is provided in a power transmission path between the engine 12 and the drive wheels 14, and in a power transmission path between the second electric motor MG2 and the drive wheels 14.

[0043] The first electric motor MG1 and the second electric motor MG2 are respectively known rotating electric machines, so-called motor generators, and are provided in a non-rotating member, that is, a non-rotatable case 18 attached to the vehicle body.

[0044] The power transmission device 16 includes a damper 20, an input shaft 22, a speed change unit 24, a compound gear 26, a driven gear 28, a driven shaft 30, a final drive gear 32, a differential gear 34, a reduction gear 36, a reduction shaft 37, etc. in a housing 18. In addition, the power transmission device 16 includes a pair of drive shafts 38 connected to the differential gear 34, etc.

[0045] The damper 20 is connected to the crankshaft 12a of the engine 12. The input shaft 22 functions as an input rotating member of the speed change unit 24. The input shaft 22 is connected to the damper 20, and is connected to the crankshaft 12a via the damper 20 and the like. The speed change unit 24 is connected to the input shaft 22. The composite gear 26 is a rotating body on the output side of the speed change unit 24. The composite gear 26 has a drive gear 26a formed on a part of the outer peripheral surface. The drive gear 26a is an output rotating member of the speed change unit 24. The driven gear 28 meshes with the drive gear 26a. The driven shaft 30 fixes the driven gear 28 and the final drive gear 32 so as to be unable to rotate relative to each other. The final drive gear 32 has a smaller diameter than the driven gear 28 and meshes with the differential ring gear 34a. The reduction gear 36 has a smaller diameter than the driven gear 28 and meshes with the driven gear 28. The reduction shaft 37 is a gear shaft that fixes the reduction gear 36 so as to be unable to rotate relative to each other.

[0046] The second electric motor MG2 is an electric motor having a stator STmg2, a rotor core RCmg2, and a rotor shaft RSmg2. The rotor shaft RSmg2 is the rotor shaft of the second electric motor MG2. The rotor shaft RSmg2 is a hollow shaft connected to the rotor core RCmg2 on the radial inner side of the rotor core RCmg2 in a manner that is non-rotatable relative to the rotor core RCmg2, and is connected to the reduction shaft 37 by spline engagement. The outer peripheral surface of the reduction shaft 37 on the second electric motor MG2 side is connected to the inner peripheral surface of the reduction gear 36 side of the rotor shaft RSmg2 by spline engagement (see Figure 3 (a) and Figure 3 (c) The second electric motor MG2 is connected to the reduction gear 36 in a power-transmittable manner.

[0047] The speed change unit 24 includes a first electric motor MG1 and a differential mechanism 40. The differential mechanism 40 is a well-known single pinion type planetary gear device including a sun gear S, a gear carrier CA, and a ring gear R. The sun gear S is connected to the first electric motor MG1 in a manner capable of transmitting power. The gear carrier CA is connected to the engine 12 via an input shaft 22 or the like in a manner capable of transmitting power. The ring gear R is formed on a portion of the inner circumferential surface of the compound gear 26 and is integrally connected to the drive gear 26a. The differential mechanism 40 is a power distribution mechanism that mechanically distributes the power of the engine 12 input to the gear carrier CA to the first electric motor MG1 and the drive gear 26a. The speed change unit 24 is a well-known electric speed change mechanism.

[0048] The power transmission device 16 has a first axis CL1, a second axis CL2, a third axis CL3 and a fourth axis CL4. These four axes CL1, CL2, CL3 and CL4 are parallel to each other. The first axis CL1 is the rotation axis of the input shaft 22, the speed change unit 24 and the first motor MG1. The second axis CL2 is the rotation axis of the driven gear 28, the driven shaft 30 and the final transmission gear 32. The third axis CL3 is the rotation axis of the reduction gear 36 and the second motor MG2. The fourth axis CL4 is the rotation axis of the differential gear 34 and the drive shaft 38.

[0049] The housing 18 includes a shell 18a as a first housing, a housing body 18b as a second housing, and a cover 18c as a third housing. The housing 18a is connected to the engine block 12b of the engine 12 at the opened portion on the engine 12 side. The housing 18a and the housing body 18b are integrally connected by fasteners such as bolts in a manner that the opened portion on the side of the housing 18a opposite to the engine 12 matches the opened portion on the side of the housing body 18b on the engine 12 side. The housing body 18b and the cover 18c are integrally connected by fasteners in a manner that the opened portion on the side of the housing body 18b opposite to the engine 12 is blocked by the cover 18c.

[0050] The housing body 18b is a housing that includes a partition wall 18b1 that separates a gear chamber Rg that accommodates a differential gear 34, a helical gear 39, a differential mechanism 40, etc., and a motor chamber Rm that accommodates the first motor MG1 and the second motor MG2. The helical gear 39 is a gear pair formed by meshing a reduction gear 36 as a first gear disposed on the third axis CL3 and a driven gear 28 as a second gear disposed on another rotation axis parallel to the third axis CL3, that is, on the second axis CL2. In the housing 18, the gear chamber Rg is formed by the engagement of the housing 18a and the housing body 18b, and the motor chamber Rm is formed by the engagement of the housing body 18b and the cover 18c.

[0051] The electric vehicle 10 includes a power control unit (not shown), and the first electric motor MG1 , the second electric motor MG2 , and the like are controlled by the power control unit.

[0052] Figure 2 (a) and Figure 2 (b) is a diagram for explaining an example of a schematic structure of the transaxle 50 . Figure 2 (a) is a perspective view of the electric vehicle 10 as seen from the front and left side. Figure 2 (b) is a side view of the electric vehicle 10 as viewed from the left side. Figure 2 (a) and Figure 2 In (b), the transaxle 50 is accommodated in the housing 18. The transaxle 50 is a drive device including the power transmission device 16 (26a, 28, 32, 34a, 36, etc.) and the first motor MG1 and the second motor MG2. In addition, the vertical direction, forward and backward direction, and vehicle width direction in the figure represent the directions in the mounted state of the electric vehicle 10. The vehicle width direction is a horizontal direction perpendicular to the forward and backward direction of the electric vehicle 10, and is a direction parallel to the axis direction of each of the four axes CL1, CL2, CL3, and CL4.

[0053] The transaxle 50 is arranged so that the four axes CL1, CL2, CL3, and CL4 are parallel to the vehicle width direction when the transaxle 50 is mounted on the electric vehicle 10. In addition, when the transaxle 50 is mounted on the electric vehicle 10, the positions of the four axes CL1, CL2, CL3, and CL4 are arranged in the order of the second motor MG2, the driven shaft 30, the first motor MG1, and the differential gear 34 from the top to the bottom in the vertical direction, and in the order of the first motor MG1, the driven shaft 30, the differential gear 34, and the second motor MG2 from the front to the rear in the forward and reverse directions.

[0054] Figure 3 (a)~ Figure 3 (e) is a diagram for explaining an example of a structure in which the rotor shaft RSmg2 and the reduction shaft 37 are supported by the housing 18 . Figure 3 (a) Figure 3 (b) is a diagram illustrating a support structure of a comparative example, Figure 3 (c) Figure 3 (d) Figure 3 (e) is a diagram for explaining the support structure of this embodiment. Figure 3 (d) is Figure 3 (c) is a partial enlarged view of the periphery of the second bearing BR2 and the periphery of the third bearing BR3. Figure 3 (a) Figure 3 (c) Figure 3 (d) is a cross-sectional view.

[0055] exist Figure 3 (a)~ Figure 3 In (e), the electric vehicle 10 includes a first bearing BR1, a second bearing BR2, and a third bearing BR3 in the housing 18. The first bearing BR1 is a ball bearing that rotatably supports the reduction shaft 37 on the housing 18a at the end of the reduction shaft 37 on the side opposite to the second electric motor MG2. The second bearing BR2 is a ball bearing that rotatably supports the rotor shaft RSmg2 on the housing body 18b, particularly the partition wall 18b1, at the end of the rotor shaft RSmg2 on the side of the reduction gear 36. The third bearing BR3 is a ball bearing that rotatably supports the rotor shaft RSmg2 on the cover 18c at the end of the rotor shaft RSmg2 on the side opposite to the reduction gear 36.

[0056] However, in the structure in which the rotor shaft RSmg2 and the reduction shaft 37 are supported by three bearings, Figure 3 (a) and Figure 3 In the comparative example shown in (b), sometimes the thrust load (also synonymous with thrust) caused by the gear meshing reaction force in the helical gear 39 is transmitted to the rotor shaft RSmg2, and the rotor shaft RSmg2 hits the cover 18c via the third bearing BR3. In this case, since the cover 18c is the outermost surface of the housing 18 and has a large surface area, it is easy to become a sound source, and the radiated sound caused by the hitting becomes larger, and NV may be deteriorated.

[0057] Therefore, in Figure 3 (c) Figure 3 (d) and Figure 3 In the present embodiment shown in (e), the reduction shaft 37 has a large diameter portion 37a formed between the spline-fitted portion and the reduction gear 36 and having a larger diameter than the spline-fitted portion. In addition, the rotor shaft RSmg2 has a step portion RSa formed adjacent to the end portion on the third bearing BR3 side and having a larger diameter than the end portion on the third bearing BR3 side.

[0058] Furthermore, the end face of the large diameter portion 37a on the second motor MG2 side abuts against the end face of the inner ring BR2i of the second bearing BR2 on the reduction gear 36 side. In addition, the gap (also synonymous with the gap) between the end face of the step portion RSa on the third bearing BR3 side and the end face of the third bearing BR3 on the second motor MG2 side, i.e., the side gap is larger than the internal gap of the second bearing BR2. The internal gap of the second bearing BR2 is the clearance (also synonymous with the gap) between the inner ring BR2i and the outer ring BR2o of the second bearing BR2 in the direction of the third axis CL3. In the case where a thrust load is generated by the gear meshing reaction force in the helical gear 39, the clearance of the second bearing BR2 is reduced first compared to the side gap. As a result, the thrust load is transmitted from the reduction shaft 37 to the housing body 18b (partition wall 18b1), and the thrust load is received by the housing body 18b. The partition wall 18b1 is located between the gear chamber Rg and the motor chamber Rm, so that the radiated sound can be suppressed. Since the outermost cover 18c is not hit directly, the radiated sound is less likely to be transmitted.

[0059] As described above, according to the present embodiment, the end face of the large diameter portion 37a on the second motor MG2 side abuts against the end face of the inner ring BR2i of the second bearing BR2 on the reduction gear 36 side. In addition, the side clearance between the end face of the step portion RSa on the third bearing BR3 side and the end face of the third bearing BR3 on the second motor MG2 side is larger than the internal clearance of the second bearing BR2. Thus, in the case where a thrust acting on the reduction shaft 37 in the direction of the second motor MG2 is generated due to the gear meshing reaction force in the helical gear 39, the thrust acts on the inner ring BR2i of the second bearing BR2. At this time, the clearance of the second bearing BR2 is reduced first compared to the side clearance. Therefore, the thrust is transmitted to the partition wall 18b1 via the second bearing BR2 and is received by the partition wall 18b1, and is not easily transmitted to the cover 18c, and the cover 18c is not easily a sound generating portion. The partition wall 18b1 is located between the gear chamber Rg and the motor chamber Rm, so even if the thrust is transmitted to the partition wall 18b1, the radiated sound to the outside of the housing 18 can be suppressed. Therefore, NV can be suppressed.

[0060] As mentioned above, although the embodiment of the present invention was described in detail based on the drawings, the above content is only one embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

Claims

1. An electric vehicle (10), comprising: Motor (MG2); a helical gear (39), the helical gear being formed by meshing a first gear (36) arranged on a rotation axis (CL3) of the motor (MG2) and a second gear (28) arranged on another rotation axis (CL2) parallel to the rotation axis (CL3) of the motor (MG2); a gear shaft (37), the outer peripheral surface of the gear shaft on the motor (MG2) side being connected to the inner peripheral surface of the rotor shaft (RSmg2) of the motor (MG2) on the first gear (36) side by spline engagement, the gear shaft fixing the first gear (36) so as to be non-rotatable relative to the first gear; a housing (18), the housing comprising a first housing (18a), a second housing (18b) and a third housing (18c), wherein the first housing (18a) and the second housing (18b) are joined to form a gear chamber (Rg) for accommodating the helical gear (39), and the second housing (18b) and the third housing (18c) are joined to form a motor chamber (Rm) for accommodating the electric motor (MG2); a first bearing (BR1) which rotatably supports the gear shaft (37) on the first housing (18a) at an end portion of the gear shaft (37) on the side opposite to the motor (MG2); a second bearing (BR2) that rotatably supports the rotor shaft (RSmg2) on the second housing (18b) at an end portion of the rotor shaft (RSmg2) on the first gear (36) side; and a third bearing (BR3) which rotatably supports the rotor shaft (RSmg2) on the third housing (18c) at an end portion of the rotor shaft (RSmg2) on the side opposite to the first gear (36), wherein the electric vehicle (10) is characterized in that: The gear shaft (37) has a large diameter portion (37a) formed between the spline-engaged portion and the first gear (36) and having a larger diameter than the spline-engaged portion. The rotor shaft (RSmg2) has a step portion (RSa) formed adjacent to the end portion on the third bearing (BR3) side and having a larger diameter than the end portion on the third bearing (BR3) side. The end surface of the large diameter portion (37a) on the motor (MG2) side abuts against the end surface of the inner ring (BR2i) of the second bearing (BR2) on the first gear (36) side. A gap between an end surface of the step portion (RSa) on the third bearing (BR3) side and an end surface of the third bearing (BR3) on the motor (MG2) side is larger than an internal gap of the second bearing (BR2).

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