Electric vehicles

Abstract

To provide an electric vehicle suppressing NV.SOLUTION: A motor-side end surface of a large diameter part formed between a spline-fitting part at a gear shaft, and a first gear, comes in contact with a first-gear-side end surface of an inner race of a second bearing. In addition, a clearance between a third-bearing-side end surface of a step part formed so as to be adjacent to an end part on a side of a third bearing at a rotor shaft and a motor-side end surface of the third bearing is made larger than an inside clearance of the second bearing. Thereby, when thrust force acting in a direction of the motor is generated on the gear shaft, the internal clearance of the second bearing is reduced prior to the clearance between the third-bearing side end surface of the step part and the motor-side end surface of the third bearing. Accordingly, the thrust force is transmitted to a second case via the second bearing and sound radiation is suppressed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electric vehicle provided with an electric motor and one gear of a spur gear on the same rotation axis.

Background Art

[0002] An electric vehicle including an electric motor, a spur gear in which a first gear disposed on the rotation axis of the electric motor meshes with a second gear disposed on another rotation axis parallel to the rotation axis of the electric motor, a gear shaft for fixedly installing the first gear in a non-rotatable manner with respect to the electric motor side by spline fitting the outer peripheral surface on the electric motor side to the inner peripheral surface on the first gear side of the rotor shaft of the electric motor, a case having a first case and a second case, a gear chamber for accommodating the spur gear being formed by joining the first case and the second case, and a motor chamber for accommodating the electric motor being formed by the second case, a first bearing for rotatably supporting the gear shaft at an end of the gear shaft opposite to the electric motor side by the first case, and a second bearing for rotatably supporting the rotor shaft at an end of the rotor shaft on the first gear side by the second case, is well known. For example, the drive device for a motor described in Patent Document 1 is such an example. In this Patent Document 1, it is disclosed that a thrust force acting in the direction of the electric motor generated on the gear shaft due to the gear meshing reaction force in the spur gear is applied to the inner race of the second bearing, and the thrust force applied to the inner race is applied to the second case through the outer race of the second bearing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this case, there is a third case that forms a motor chamber by joining with the second case, and the rotor shaft is rotatably supported by the third case via a third bearing at the end of the rotor shaft opposite to the first gear side. In this case, for example, thrust force transmitted to the rotor shaft directly or indirectly via the second bearing from the gear shaft may be transmitted to the third case via the third bearing. If this happens, the thrust force may cause the rotor shaft to strike the third case via the third bearing, potentially worsening NV. "NV" is a general term for noise and vibration generated in a vehicle, and represents at least one of the noise and vibration in a vehicle.

[0005] This invention was made against the above circumstances, and its objective is to provide an electric vehicle that can suppress NVH (noise, vibration, and harshness). [Means for solving the problem]

[0006] The gist of the first invention is (a) an electric motor, a helical gear in which a first gear arranged on the rotation axis of the electric motor and a second gear arranged on another rotation axis parallel to the rotation axis of the electric motor mesh, a gear shaft for fixing the first gear so as not to rotate relative to the inner circumferential surface of the rotor shaft of the electric motor on the first gear side is connected by spline fitting to the outer circumferential surface of the electric motor side, a case having a first case, a second case, and a third case, wherein a gear chamber for housing the helical gear is formed by joining the first case and a motor chamber for housing the electric motor is formed by joining the second case and the third case An electric vehicle comprising: a second bearing that rotatably supports the rotor shaft in the second case; and a third bearing that rotatably supports the rotor shaft in the third case at the end of the rotor shaft opposite to the first gear side, wherein (b) the gear shaft has a large-diameter portion formed between the spline fitting portion and the first gear, which has a larger diameter than the spline fitting portion; (c) the rotor shaft has a stepped portion formed adjacent to the end on the third bearing side, which has a larger diameter than the end on the third bearing side; (d) the end face of the large-diameter portion on the motor side is in contact with the end face of the inner race of the second bearing on the first gear side; and (e) the clearance between the end face of the stepped portion on the third bearing side and the end face of the third bearing on the motor side is the clearance between the second bearing possesses The key difference is that it is made larger than the internal clearance. [Effects of the Invention]

[0007] According to the first invention, the motor-side end face of the large-diameter portion, which is larger in diameter than the spline-fitting portion and formed between the spline-fitting portion of the gear shaft and the first gear, is in contact with the first gear-side end face of the inner race of the second bearing. In addition, the clearance between the third bearing-side end face of the stepped portion, which is larger in diameter than the third bearing-side end and formed adjacent to the third bearing-side end of the rotor shaft, and the motor-side end face of the third bearing is the second bearing possesses The internal clearance is made larger than the motor clearance. As a result, when a thrust force acting on the gear shaft in the direction of the motor is generated by the gear meshing reaction force in the helical gear, the thrust force is applied to the inner race of the second bearing. At this time, the internal clearance of the second bearing, that is, the play between the inner and outer races, is reduced before the clearance between the end face of the stepped portion on the third bearing side and the end face of the third bearing on the motor side. Therefore, the thrust force acting on the gear shaft in the direction of the motor is transmitted to the second case via the second bearing and absorbed by the second case, making it difficult to transmit to the third case, thus making it difficult for the third case to become a noise-generating part. Since the second case is located between the gear chamber and the motor chamber, even if the thrust force is transmitted to the second case, the noise radiated outside the case is suppressed. Thus, NV (noise, vibration, and noise) can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This figure illustrates an example of a schematic configuration of an electric vehicle to which the present invention is applied. [Figure 2] This diagram illustrates an example of the schematic configuration of a drive unit. [Figure 3] This diagram illustrates an example of a structure that supports the rotor shaft and reduction shaft in a case. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0010] Figure 1 is a diagram illustrating an example of the schematic configuration of an electric vehicle 10 to which the present invention is applied. In Figure 1, the electric vehicle 10 is a hybrid vehicle equipped with an engine 12, a first electric motor MG1, and a second electric motor MG2. The electric vehicle 10 also includes drive wheels 14 and a power transmission device 16. The power transmission device 16 is provided in the power transmission path between the engine 12 and the drive wheels 14, and in the power transmission path between the second electric motor MG2 and the drive wheels 14.

[0011] The first electric motor MG1 and the second electric motor MG2 are each known rotating electric machines, so-called motor generators, and are housed in a non-rotatable case 18, which is a non-rotating member attached to the vehicle body.

[0012] The power transmission device 16 includes a damper 20, an input shaft 22, a transmission unit 24, a compound gear 26, a driven gear 28, a driven shaft 30, a final gear 32, a differential gear 34, a reduction gear 36, a reduction shaft 37, etc., within a case 18. The power transmission device 16 also includes a pair of drive shafts 38 connected to the differential gear 34, etc.

[0013] The damper 20 is connected to the crankshaft 12a of the engine 12. The input shaft 22 functions as the input rotating member of the transmission unit 24. The input shaft 22 is connected to the damper 20 and, via the damper 20, is connected to the crankshaft 12a. The transmission unit 24 is connected to the input shaft 22. The compound gear 26 is the output rotating body of the transmission unit 24. The compound gear 26 has a drive gear 26a formed on a part of its outer circumference. The drive gear 26a is the output rotating member of the transmission unit 24. The driven gear 28 meshes with the drive gear 26a. The driven shaft 30 fixes the driven gear 28 and the final gear 32 so that they cannot rotate relative to each other. The final 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 that it cannot rotate relative to the reduction gear 36.

[0014] The second 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 motor MG2. The rotor shaft RSmg2 is a hollow shaft that is connected to the rotor core RCmg2 radially inward and is not rotatable relative to the rotor core RCmg2, and is connected to the reduction shaft 37 by spline fitting. The reduction shaft 37 is connected to the inner circumferential surface of the rotor shaft RSmg2 on the reduction gear 36 side by spline fitting on the outer circumferential surface on the second motor MG2 side (see Figure 3). The second motor MG2 is connected to the reduction gear 36 in a way that allows power transmission.

[0015] The transmission unit 24 comprises a first electric motor MG1 and a differential mechanism 40. The differential mechanism 40 is a known single-pinion type planetary gear system comprising a sun gear S, a carrier CA, and a ring gear R. The sun gear S is connected to the first electric motor MG1 so as to transmit power. The carrier CA is connected to the engine 12 so as to transmit power via an input shaft 22, etc. The ring gear R is formed on a part of the inner circumferential surface of a composite gear 26 and is integrally connected to the drive gear 26a. The differential mechanism 40 is a power splitting mechanism that mechanically divides the power of the engine 12 input to the carrier CA between the first electric motor MG1 and the drive gear 26a. The transmission unit 24 is a known electric transmission mechanism.

[0016] 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 gearbox 24, and the first electric motor MG1. The second axis CL2 is the rotation axis of the driven gear 28, the driven shaft 30, and the final gear 32. The third axis CL3 is the rotation axis of the reduction gear 36 and the second electric motor MG2. The fourth axis CL4 is the rotation axis of the differential gear 34 and the drive shaft 38.

[0017] The case 18 comprises a housing 18a as a first case, a case body 18b as a second case, and a cover 18c as a third case. The engine block 12b of the engine 12 is connected to the open portion of the housing 18a on the engine 12 side. The housing 18a and the case body 18b are integrally connected by fasteners such as bolts so that the open portion of the housing 18a on the opposite side of the engine 12 and the open portion of the case body 18b on the engine 12 side are aligned. The case body 18b and the cover 18c are integrally connected by fasteners so that the open portion of the case body 18b on the opposite side of the engine 12 is closed by the cover 18c.

[0018] The case body 18b is a case including a partition wall 18b1 that divides a gear chamber Rg for housing a differential gear 34, a bevel gear 39, a differential mechanism 40, etc., and a motor chamber Rm for housing a first electric motor MG1 and a second electric motor MG2. The bevel gear 39 is a gear pair in which a reduction gear 36 as a first gear disposed on a third axis line CL3 and a driven gear 28 as a second gear disposed on a second axis line CL2, which is another rotation axis line parallel to the third axis line CL3, are engaged with each other. In the case 18, the gear chamber Rg is formed by joining the housing 18a and the case body 18b, and the motor chamber Rm is formed by joining the case body 18b and the cover 18c.

[0019] The electric vehicle 10 includes a power control unit (not shown), and the first electric motor MG1, the second electric motor MG2, etc. are controlled by the power control unit.

[0020] FIG. 2 is a diagram for explaining an example of the schematic configuration of the transaxle 50. (a) of FIG. 2 is a perspective view of the electric vehicle 10 from the front and left side. (b) of FIG. 2 is a side view of the electric vehicle 10 from the left side. In FIG. 2, the transaxle 50 is housed in the case 18. The transaxle 50 is a drive device including a power transmission device 16 (26a, 28, 32, 34a, 36, etc.) and the first electric motor MG1 and the second electric motor MG2. Note that the vertical direction, the forward / backward direction, and the vehicle width direction in the figure indicate the directions in the mounted state of the electric vehicle 10. The vehicle width direction is a horizontal direction perpendicular to the forward / backward direction of the electric vehicle 10 and is a direction parallel to the axial direction of each of the four axis lines CL1, CL2, CL3, and CL4.

[0021] In the mounted state in the electric vehicle 10, the transaxle 50 is arranged such that each of the four axes CL1, CL2, CL3, and CL4 is parallel to the vehicle width direction. Also, in the mounted state in the electric vehicle 10, the positions of each of the four axes CL1, CL2, CL3, and CL4 are in the order of the second electric motor MG2, the driven shaft 30, the first electric motor MG1, and the differential gear 34 from above to below in the vertical direction, and in the order of the first electric motor MG1, the driven shaft 30, the differential gear 34, and the second electric motor MG2 from the front to the rear in the forward and reverse direction.

[0022] FIG. 3 is a diagram for explaining an example of a structure for supporting the rotor shaft RSm2 and the reduction shaft 37 in the case 18. FIGS. 3(a) and 3(b) are diagrams for explaining the support structure of the comparative example, and FIGS. 3(c), 3(d), and 3(e) are diagrams for explaining the support structure of the present embodiment. FIG. 3(d) is a partially enlarged view of the periphery of the second bearing BR2 and the periphery of the third bearing BR3 in FIG. 3(c). FIGS. 3(a), 3(c), and 3(d) are cross-sectional views.

[0023] In FIG. 3, the electric vehicle 10 includes a first bearing BR1, a second bearing BR2, and a third bearing BR3 in the case 18. The first bearing BR1 is a ball bearing that rotatably supports the reduction shaft 37 at an end of the reduction shaft 37 opposite to the second electric motor MG2 side in the housing 18a. The second bearing BR2 is a ball bearing that rotatably supports the rotor shaft RSm2 at an end of the rotor shaft RSm2 on the reduction gear 36 side in the case body 18b, particularly the partition wall 18b1. The third bearing BR3 is a ball bearing that rotatably supports the rotor shaft RSm2 at an end of the rotor shaft RSm2 opposite to the reduction gear 36 side in the cover 18c.

[0024] Incidentally, in a structure where the rotor shaft RSmg2 and reduction shaft 37 are supported by three bearings, in the comparative example shown in Figures 3(a) and (b), the thrust load (thrust force) due to the gear meshing reaction force in the helical gear 39 is transmitted to the rotor shaft RSmg2, and the rotor shaft RSmg2 may strike the cover 18c via the third bearing BR3. In this case, since the cover 18c is the outermost surface of the case 18 and has a large surface area, it is prone to becoming a sound-producing part, and the radiated noise from being struck may increase, potentially worsening NV (Noise, Vibration, and Harshness).

[0025] Therefore, in the embodiment shown in Figures 3(c), (d), and (e), the reduction shaft 37 has a large-diameter portion 37a formed between the spline-fitting portion and the reduction gear 36, which has a larger diameter than the spline-fitting portion. In addition, the rotor shaft RSmg2 has a stepped portion RSa formed adjacent to the end on the third bearing BR3 side, which has a larger diameter than the end on the third bearing BR3 side.

[0026] Furthermore, the end face of the large-diameter portion 37a on the second motor MG2 side is in contact with the end face of the inner race BR2i of the second bearing BR2 on the reduction gear 36 side. In addition, the side clearance, which is the clearance (or gap) between the end face of the stepped portion RSa on the third bearing BR3 side and the end face of the third bearing BR3 on the second motor MG2 side, is made larger than the internal clearance of the second bearing BR2. The internal clearance of the second bearing BR2 is the play (or gap) in the direction of the third axis CL3 between the inner race BR2i and the outer race BR2o of the second bearing BR2. When a thrust load is generated due to the gear meshing reaction force in the helical gear 39, the play in the second bearing BR2 is reduced before the side clearance. As a result, the thrust load is transmitted from the reduction shaft 37 to the case body 18b (partition wall 18b1), and the thrust load is absorbed by the case body 18b. Since the partition wall 18b1 is located between the gear chamber Rg and the motor chamber Rm, it is possible to suppress radiated sound. Because the outermost cover 18c is not directly struck, the transmission of radiated sound is made more difficult.

[0027] As described above, in this embodiment, the end face of the large-diameter portion 37a on the second motor MG2 side is in contact with the end face of the inner race BR2i of the second bearing BR2 on the reduction gear 36 side. In addition, the side clearance between the end face of the stepped portion RSa on the third bearing BR3 side and the end face of the third bearing BR3 on the second motor MG2 side is made larger than the internal clearance of the second bearing BR2. As a result, when a thrust force acting on the reduction shaft 37 in the direction of the second motor MG2 is generated by the gear meshing reaction force in the helical gear 39, the thrust force is applied to the inner race BR2i of the second bearing BR2. At this time, the play in the second bearing BR2 is eliminated before the side clearance. Therefore, the thrust force is transmitted to the partition wall 18b1 via the second bearing BR2 and received by the partition wall 18b1, making it difficult to transmit to the cover 18c, and thus making it difficult for the cover 18c to become a noise-generating part. Since the bulkhead 18b1 is located between the gear chamber Rg and the motor chamber Rm, even if thrust force is transmitted to the bulkhead 18b1, the sound radiated outside the case 18 is suppressed. Therefore, NV (noise, vibration, and noise) can be suppressed.

[0028] Although embodiments of the present invention have been described in detail above with reference to the drawings, the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of Symbols]

[0029] 10: Electric vehicle 18: Case 18a: Housing (first case) 18b: Case body (second case) 18b1: Bulkhead (second case) 18c: Cover (third case) 28: Driven gear (second gear) 36: Reduction gear (first gear) 37: Reduction shaft (gear shaft) 37a: Large diameter section 39: Helical gear BR1: First bearing BR2: Second bearing BR2i: Inner race BR3: Third bearing CL2: Second axis (another axis of rotation parallel to the axis of rotation of the electric motor) CL3: Third axis (axis of rotation of the electric motor) MG2: Second electric motor (electric motor) RSmg2: Rotor shaft (rotor shaft of the electric motor) RSa: Stepped section Rg: Gear chamber Rm: Motor chamber

Claims

[Claim 1] Electric motor and, A helical gear is formed by meshing a first gear, which is positioned on the rotation axis of the electric motor, with a second gear, which is positioned on another rotation axis parallel to the rotation axis of the electric motor. A gear shaft is provided to which the first gear is fixed so as not to rotate relative to the inner circumferential surface of the rotor shaft of the electric motor, the outer circumferential surface of the electric motor is connected by spline fitting to the inner circumferential surface of the rotor shaft of the electric motor on the first gear side, A case having a first case, a second case, and a third case, wherein a gear chamber for housing the helical gear is formed by joining the first case and the second case, and a motor chamber for housing the electric motor is formed by joining the second case and the third case, A first bearing supports the gear shaft rotatably in the first case at the end of the gear shaft opposite to the motor side, A second bearing supports the rotor shaft rotatably in the second case at the end of the rotor shaft on the first gear side, A third bearing supports the rotor shaft rotatably in the third case at the end of the rotor shaft opposite to the first gear side, An electric vehicle equipped with, The gear shaft has a larger diameter portion formed between the spline fitting portion and the first gear, which is larger in diameter than the spline fitting portion. The rotor shaft has a stepped portion formed adjacent to the end on the third bearing side, which has a larger diameter than the end on the third bearing side. The end face of the large-diameter portion on the motor side is in contact with the end face of the inner race of the second bearing on the first gear side. An electric vehicle characterized in that the clearance between the end face of the stepped portion on the third bearing side and the end face of the third bearing on the motor side is greater than the internal clearance of the second bearing.

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