Power transmission mechanism and vehicle

Abstract

The power transmission mechanism (2) includes left and right drive shafts (3L, 3R) for transmitting rotational torque from a drive source to drive wheels arranged on the left and right sides of the vehicle, and the numbers of rolling elements (23, 33) of the sliding constant velocity universal joints (6L, 6R) on the right drive shaft (3R) and the left drive shaft (3L) are different from each other.

Description

Technical Field

[0001] The present invention relates to a power transmission mechanism and a vehicle. Background Art

[0002] As a power transmission mechanism for transmitting the rotational torque from a driving source such as an engine or an electric motor to the left and right driving wheels mounted on the vehicle, a drive shaft is used, which is composed of a constant velocity universal joint arranged on the outer side of the driving wheel side, a constant velocity universal joint arranged on the inner side on the side opposite to the driving wheel side, and an intermediate shaft connecting the two constant velocity universal joints.

[0003] Usually, the fixed type constant velocity universal joint is used as the constant velocity universal joint on the outer side, which can achieve a large working angle but does not cause axial displacement. On the other hand, the sliding type constant velocity universal joint is used as the constant velocity universal joint on the inner side, which has a small maximum working angle but can achieve an axial displacement while achieving the working angle.

[0004] However, it is known that in such a drive shaft, when the rotational torque is transmitted in a state where the constant velocity universal joint has achieved a working angle, an induced thrust in the axial direction is generated during the rotation. The induced thrust is an axial force generated in accordance with the number of rollers or balls during one rotation of the constant velocity universal joint, and there is a tendency to be more easily generated in a sliding constant velocity universal joint than in a fixed constant velocity universal joint. For example, in the case of a tripod type constant velocity universal joint (TJ) with three rollers, the induced thrust is generated three times in one rotation, and in the case of a double-ring type constant velocity universal joint (DOJ) with six balls, the induced thrust is generated six times in one rotation. When such an induced thrust resonates with the mounting mechanism of the engine, transmission or differential device, it becomes the main cause of vibration and abnormal noise of the vehicle.

[0005] In this regard, a technology has been proposed in the past, which suppresses the vibration and abnormal noise caused by the induced thrust by staggering the angular phase of the rolling elements (rollers or balls) of the sliding constant velocity universal joint on the inner side and the fixed constant velocity universal joint on the outer side (see Patent Document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 10-122253 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in recent years, the expectation for improving the so-called NVH characteristics of noise, vibration, and harshness has become stronger than before. In particular, in motor-driven vehicles that seek quietness, there are also cases where the weight is lighter than that of engine-driven vehicles, or the rotational torque input to the drive shaft during starting and acceleration is higher, and in the existing technology, it may not be possible to fully suppress the vibration and abnormal sound caused by the induced thrust.

[0011] Therefore, an object of the present invention is to provide a power transmission mechanism capable of effectively suppressing vibration and abnormal noise caused by induced thrust, and a vehicle including the power transmission mechanism.

[0012] Solutions to Solve Problems

[0013] The present invention is a power transmission mechanism, which has left and right drive shafts for transmitting rotational torque from a drive source to drive wheels arranged on the left and right sides of a vehicle. The left and right drive shafts have: an intermediate shaft; a fixed constant velocity universal joint connected to the end of the intermediate shaft on the drive wheel side; and a sliding constant velocity universal joint connected to the end of the intermediate shaft on the side opposite to the drive wheel side. In addition, the sliding constant velocity universal joint has: an outer coupling member having a rolling groove formed on the inner peripheral surface; a rolling element arranged in the rolling groove in a manner that allows rolling; and an inner coupling member that allows angular displacement and axial displacement between the inner coupling member and the outer coupling member via the rolling element and transmits the rotational torque.

[0014] In the present invention, in the left and right drive shafts of such a power transmission mechanism, the number of rolling elements of each sliding constant velocity universal joint is made different from each other. Thus, the frequency (timing) at which the induced thrust generated in the left and right sliding constant velocity universal joints becomes the maximum can be made different from each other. As a result, the induced thrust generated in the left and right sliding constant velocity universal joints is not easy to resonate, so that the vibration and abnormal noise generated in the vehicle due to the induced thrust can be effectively suppressed.

[0015] Furthermore, by making the number of rolling elements in each fixed constant velocity universal joint different from each other in the left and right drive shafts, the frequency (timing) at which the induced thrust generated in each fixed constant velocity universal joint becomes the maximum can also be made different from each other. As a result, the induced thrust generated in the left and right fixed constant velocity universal joints is less likely to resonate, thereby more effectively suppressing vibration and abnormal noise caused by the induced thrust.

[0016] The present invention is particularly suitable for the case where the driving source is an electric motor. That is, in a motor-driven vehicle using an electric motor as a driving source, a higher quietness is sought compared to an engine-driven vehicle, and there is also a case where the vehicle is lightweight and the rotational torque input to the drive shaft during starting and acceleration is high, and there is a tendency for the vibration and abnormal noise caused by the induced thrust to become significant. Therefore, in such a motor-driven vehicle, a particularly large effect can be obtained by applying the present invention.

[0017] Furthermore, by applying the power transmission mechanism of the present invention to a vehicle, the generation of vibration and abnormal noise caused by the induced thrust can be highly suppressed, and a vehicle having excellent NVH characteristics can be provided.

[0018] Effects of the Invention

[0019] According to the present invention, vibration and abnormal noise caused by induced thrust can be effectively suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a plan view showing a schematic structure of a power transmission mechanism mounted on an electric vehicle.

[0021] Figure 2 It is a longitudinal sectional view of the left and right drive shafts according to one embodiment of the present invention.

[0022] Figure 3 This is a cross-sectional view of a tripod type constant velocity universal coupling.

[0023] Figure 4 It is a cross-sectional view of a double-ring constant velocity universal coupling.

[0024] Figure 5 This is a cross-sectional view of a fixed constant velocity universal joint with six balls.

[0025] Figure 6 This is a cross-sectional view of a fixed constant velocity universal joint with eight balls.

[0026] Figure 7 It is a longitudinal sectional view of left and right drive shafts according to another embodiment of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, the embodiments of the present invention will be described based on the accompanying drawings. It should be noted that, in the drawings used to describe the present invention, components, constituent parts, and other constituent elements having the same function or shape are marked with the same reference numerals as long as they can be distinguished, so that their description is omitted after one description.

[0028] exist Figure 1 Schematic diagram of the structure of a power transmission mechanism mounted on an electric vehicle is shown in FIG.

[0029] Figure 1 The electric vehicle 1 shown is a motor-driven vehicle of a front-wheel drive type. The electric vehicle 1 is provided with left and right drive shafts 3L and 3R as a power transmission mechanism 2 for transmitting the rotational torque of the electric motor M as a drive source to the left and right front wheels W as drive wheels. Each drive shaft 3L and 3R is provided with: an intermediate shaft 4L and 4R; a fixed constant velocity universal joint 5L and 5R on the outer side (outer side of the vehicle) connected to the end of the intermediate shaft 4L and 4R on the front wheel W side; and a sliding constant velocity universal joint 6L and 6R on the inner side (inner side of the vehicle) connected to the end of the intermediate shaft 4L and 4R on the side opposite to the front wheel W side. The electric motor M is connected to the left and right front wheels W via such drive shafts 3L and 3R, so that the rotational torque can be transmitted from the electric motor M to each front wheel W.

[0030] exist Figure 2 Detailed Description of the Invention The structure of the left and right drive shafts according to the embodiment of the present invention is shown in FIG.

[0031] First, refer to Figure 2 The structure of the fixed constant velocity universal joints 5L and 5R provided on the left and right drive shafts 3L and 3R will be described.

[0032] like Figure 2 As shown, the fixed constant velocity universal joints 5L, 5R of each drive shaft 3L, 3R respectively include an outer ring 7 as an outer coupling member connected to the above-mentioned front wheel W, an inner ring 8 as an inner coupling member connected to the intermediate shafts 4L, 4R, a plurality of balls 9 as rolling bodies, and a retaining frame 10 as main components.

[0033] The outer ring 7 is a cup-shaped member with one end open, and a plurality of arc-shaped rolling grooves 7a extending in the axial direction are formed at equal intervals on the inner circumferential surface of the outer ring 7. On the other hand, the inner ring 8 is a cylindrical member, and a plurality of arc-shaped rolling grooves 8a are formed at equal intervals on the outer circumferential surface of the inner ring 8 to oppose the rolling grooves 7a of the outer ring 7. A ball 9 is arranged between the rolling grooves 7a of the outer ring 7 and the rolling grooves 8a of the inner ring 8, and each ball 9 is held by a retainer 10 sandwiched between the outer ring 7 and the inner ring 8 so as to be able to roll. In addition, a protective cover 11 is installed between the outer ring 7 and the intermediate shafts 4L and 4R for the purpose of preventing foreign matter from entering the coupling or preventing the grease sealed in the coupling from leaking.

[0034] In the fixed constant velocity universal joints 5L and 5R, when a working angle is applied between the outer ring 7 and the inner ring 8, the balls 9 move along the raceway grooves 7a and 8a, so that the balls 9 are always maintained within the plane bisecting the working angle at any working angle. Thus, the rotational torque is transmitted at a constant speed between the outer ring 7 and the inner ring 8 via the balls 9.

[0035] Here, in the left and right drive shafts 3L and 3R of the present embodiment, fixed constant velocity universal joints 5L and 5R are used as fixed constant velocity universal joints of the same structure. In contrast, sliding constant velocity universal joints 6L and 6R provided in the respective drive shafts 3L and 3R are used as sliding constant velocity universal joints of different structures. Specifically, in the present embodiment, a tripod type constant velocity universal joint (TJ) 20 is used as the sliding constant velocity universal joint 6R on the right side, and a double-ring type constant velocity universal joint (EDJ) 30 is used as the sliding constant velocity universal joint 6L on the left side.

[0036] Next, refer to Figure 2 as well as Figure 3 The structure of the tripod type constant velocity universal joint 20 used as the right sliding type constant velocity universal joint 6R will be described.

[0037] like Figure 2 as well as Figure 3 As shown, the tripod type constant velocity universal joint 20 includes an outer ring 21 as an outer coupling member connected to the electric motor M, a tripod member 22 as an inner coupling member connected to the intermediate shaft 4R, and three rollers 23 as rolling elements as main components.

[0038] The outer ring 21 is a cup-shaped member with one end open. Three linear raceway grooves 21a extending in the axial direction are formed at equal intervals on the inner circumferential surface of the outer ring 21. The tripod member 22 has a cylindrical boss 24 and three pins 25 protruding in the radial direction from the boss 24. A roller unit 26 composed of a roller 23 and the like is mounted on each pin 25. The roller unit 26 is composed of a roller 23 as an outer ring, an inner ring 27 arranged inside the roller 23 and externally fitted on the pin 25, and a plurality of needle rollers 28 sandwiched between the roller 23 and the inner ring 27. One roller unit 26 is arranged in each raceway groove 21a of the outer ring 21, and the roller 23 moves along the raceway groove 21a, so that the tripod member 22 can allow angular displacement and axial displacement relative to the outer ring 21 and transmit rotational torque. Further, similarly to the above-mentioned fixed type constant velocity universal joints 5L and 5R, a protective cover 12 is attached between the outer ring 21 and the intermediate shaft 4R.

[0039] Next, refer to Figure 2 as well as Figure 4 The structure of the double-turn constant velocity universal joint 30 used as the left sliding type constant velocity universal joint 6L will be described.

[0040] like Figure 2 as well as Figure 4As shown, the double-ring constant velocity universal joint 30 includes an outer ring 31 as an outer coupling member connected to the above-mentioned electric motor M, an inner ring 32 as an inner coupling member connected to the intermediate shaft 4L, eight balls 33 as rolling elements, and a retainer 34 as main components.

[0041] The outer ring 31 is a cup-shaped member with one end open, and eight linear raceway grooves 31a extending in the axial direction are formed on the inner circumferential surface of the outer ring 31 at equal intervals in the circumferential direction. On the other hand, the inner ring 32 is a cylindrical member, and eight linear raceway grooves 32a are formed on the outer circumferential surface of the inner ring 32 at equal intervals in the circumferential direction to oppose the raceway grooves 31a of the outer ring 31. One ball 33 is arranged between the raceway grooves 31a of the outer ring 31 and the raceway grooves 32a of the inner ring 32, and each ball 33 is held by a cage 34 sandwiched between the outer ring 31 and the inner ring 32 so that it can roll. Each ball 33 moves along each raceway groove 31a, 32a, so that the inner ring 32 can allow angular displacement and axial displacement relative to the outer ring 31 and transmit the rotational torque. In addition, similar to the above-mentioned fixed constant velocity universal joints 5L and 5R, a protective cover 13 is installed between the outer ring 31 and the intermediate shaft 4L.

[0042] As described above, in the power transmission mechanism 2 of the present embodiment, as the sliding constant velocity universal joints 6L and 6R provided for the left and right drive shafts 3L and 3R, sliding constant velocity universal joints having different numbers of rolling elements are used. Therefore, when the drive shafts 3L and 3R rotate, the induced thrust is generated in different ways in each sliding constant velocity universal joint 6L and 6R. That is, since the induced thrust is generated in accordance with the number of rollers or balls in one rotation, the maximum induced thrust is generated every 120° rotation in the tripod type constant velocity universal joint 20 provided with three rollers, and the maximum induced thrust is generated every 45° rotation in the double-coil type constant velocity universal joint 30 provided with eight balls.

[0043] Thus, in the present embodiment, by using the sliding constant velocity universal joints 6L and 6R with different numbers of rolling elements, the frequencies (timings) at which the induced thrust generated in the sliding constant velocity universal joints 6L and 6R becomes maximum can be made different from each other. As a result, the induced thrust generated in the sliding constant velocity universal joints 6L and 6R is less likely to resonate, and vibration and abnormal noise generated in the vehicle due to the induced thrust can be effectively suppressed.

[0044] On the other hand, since the fixed constant velocity universal joint is less likely to generate induced thrust than the sliding constant velocity universal joint, in this embodiment, the fixed constant velocity universal joint 5R on the right and the fixed constant velocity universal joint 5L on the left use fixed constant velocity universal joints with the same number of balls. The number of balls provided by the left and right fixed constant velocity universal joints 5L and 5R can be, for example, Figure 5 Six as shown, or Figure 6 Eight as shown.

[0045] Furthermore, in order to further suppress vibration and abnormal noise caused by the induced thrust, fixed-type constant velocity universal joints including different numbers of balls may be used as the left and right fixed-type constant velocity universal joints 5L and 5R.

[0046] exist Figure 7 2 shows an embodiment using a fixed constant velocity universal joint having balls of different numbers.

[0047] exist Figure 7 In the embodiment shown in the figure, as the fixed constant velocity universal joint 5R provided for the right drive shaft 3R, a fixed constant velocity universal joint 5R is used. Figure 6 As the fixed constant velocity universal joint 5L provided for the left drive shaft 3L, a fixed constant velocity universal joint having eight balls 9 as shown in FIG. Figure 5 It should be noted that, similarly to the above-mentioned embodiment, the sliding type constant velocity universal joints 6L and 6R have a tripod type constant velocity universal joint 20 on the right and a double coil type constant velocity universal joint 30 on the left.

[0048] In this way, by using fixed constant velocity universal joints having different numbers of rolling elements as the left and right fixed constant velocity universal joints 5L and 5R, the frequencies (timings) at which the induced thrust generated in the left and right fixed constant velocity universal joints 5L and 5R becomes maximum can be made different. As a result, the induced thrust generated in the left and right fixed constant velocity universal joints 5L and 5R is less likely to resonate, so that vibration and abnormal noise caused by the induced thrust can be more effectively suppressed.

[0049] In addition, Figure 7In the embodiment shown, the number of rolling elements is different between the fixed constant velocity universal joint 5R and the sliding constant velocity universal joint 6R provided in the right drive shaft 3R, and between the fixed constant velocity universal joint 5L and the sliding constant velocity universal joint 6L provided in the left drive shaft 3L. That is, in the right drive shaft 3R, a combination of the fixed constant velocity universal joint 5R provided with eight balls 9 and the tripod type constant velocity universal joint 20 provided with three rollers 23 is adopted, and in the left drive shaft 3L, a combination of the fixed constant velocity universal joint 5L provided with six balls 9 and the double-coil type constant velocity universal joint 30 provided with eight balls 33 is adopted, thereby making the number of rolling elements different between the fixed constant velocity universal joint and the sliding constant velocity universal joint. Therefore, the thrust induced between the fixed constant velocity universal joint and the sliding constant velocity universal joint provided in each of the drive shafts 3L and 3R is unlikely to resonate, and vibration and abnormal noise are unlikely to occur.

[0050] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Various changes can be made within the range which does not deviate from the summary of this invention.

[0051] In the above-mentioned embodiment, a so-called ball cage type constant velocity universal joint (BJ) in which the raceway groove is composed of only arc portions is used as the fixed constant velocity universal joint, but a so-called undercut-free constant velocity universal joint (UJ) in which the raceway groove is composed of arc portions and straight portions may also be used. In addition, the fixed constant velocity universal joint is not limited to a fixed constant velocity universal joint having six balls or eight balls, and may also be a fixed constant velocity universal joint having more than eight balls.

[0052] In addition, the combination of the sliding constant velocity universal coupling on the right side and the sliding constant velocity universal coupling on the left side is not limited to the above-mentioned embodiment. For example, when the sliding constant velocity universal coupling on one side is a tripod type constant velocity universal coupling (TJ) with three rollers, the sliding constant velocity universal coupling on the other side may be a double-ring type constant velocity universal coupling (DOJ) with six balls instead of the above-mentioned double-ring type constant velocity universal coupling (EDJ) with eight balls. In addition, the sliding constant velocity universal coupling on one side may be a double-ring type constant velocity universal coupling (EDJ) with eight balls, and the sliding constant velocity universal coupling on the other side may be a double-ring type constant velocity universal coupling (DOJ) with six balls.

[0053] In addition, the present invention is not limited to front-wheel drive vehicles, but can also be applied to rear-wheel drive vehicles and four-wheel drive vehicles. In addition, the motor-driven vehicle to which the present invention is applied can be a single-motor type in which a common electric motor drives the left and right drive wheels, or a dual-motor type in which two motors independently drive the left and right drive wheels. In addition, a power transmission mechanism such as a speed reducer can be interposed between the electric motor and the sliding constant velocity universal coupling of the drive shaft.

[0054] In addition, in the present invention, in order to more reliably suppress the vibration and abnormal noise caused by the induced thrust, the phases of all rolling elements of each constant velocity universal coupling in the circumferential direction of the coupling may be different between the constant velocity universal couplings that are intended to avoid the resonance of the induced thrust. That is, the phases of all rolling elements of each constant velocity universal coupling in the circumferential direction of the coupling may be different between the left and right sliding constant velocity universal couplings 6L and 6R, between the left and right fixed constant velocity universal couplings 5L and 5R, or between the fixed constant velocity universal couplings 5L and 5R and the sliding constant velocity universal couplings 6L and 6R. Thus, the vibration and abnormal noise caused by the induced thrust can be more reliably suppressed.

[0055] As described above, according to the present invention, by making the left and right sliding constant velocity universal couplings that are prone to generating induced thrust use sliding constant velocity universal couplings with different numbers of rolling elements, the timing of generating the maximum induced thrust in the left and right sliding constant velocity universal couplings can be different, thereby effectively suppressing the vibration and abnormal noise caused by the induced thrust. As a result, vibration and abnormal noise are not easily generated in the vehicle, thereby providing a vehicle with excellent NVH characteristics. The present invention is not limited to motor-driven vehicles such as electric vehicles, but can also be applied to engine-driven vehicles. Among them, in motor-driven vehicles where the vibration and abnormal noise caused by the induced thrust are most significant, a particularly large effect can be obtained by applying the present invention.

[0056] Description of Reference Numerals

[0057] 1 Electric vehicles

[0058] 2 Power transmission mechanism

[0059] 3L, 3R drive shaft

[0060] 4L, 4R intermediate shaft

[0061] 5L, 5R Fixed Constant Velocity Universal Couplings

[0062] 6L, 6R sliding constant velocity universal coupling

[0063] 7 Outer ring (outer coupling member)

[0064] 7a Roller groove

[0065] 8 Inner ring (inner coupling member)

[0066] 8a Roller groove

[0067] 9 Balls (rolling elements)

[0068] 10 Cage

[0069] 20 Tripod type constant velocity universal coupling

[0070] 21 Outer ring (outer coupling member)

[0071] 21a Roller groove

[0072] 22 Tripod member (inner coupling member)

[0073] 23 Roller (rolling element)

[0074] 30 Double-ring constant velocity universal coupling

[0075] 31 Outer ring (outer coupling member)

[0076] 31a Roller groove

[0077] 32 Inner ring (inner coupling member)

[0078] 32a Roller groove

[0079] 33 Ball (rolling element)

[0080] 34 Cage

[0081] M Electric motor (drive source)

[0082] W Front wheels (driving wheels).

Claims

1. A power transmission mechanism comprising left and right drive shafts for transmitting a rotational torque from a drive source to drive wheels provided on the left and right sides of a vehicle, wherein: The left and right drive shafts include: an intermediate shaft; a fixed constant velocity universal joint connected to the end of the intermediate shaft on the drive wheel side; and a sliding constant velocity universal joint connected to the end of the intermediate shaft on the side opposite to the drive wheel side. The sliding constant velocity universal joint comprises: an outer joint member having a raceway groove formed on an inner peripheral surface; rolling elements arranged in the raceway groove in a rollable manner; and an inner joint member that allows angular displacement and axial displacement between the inner joint member and the outer joint member via the rolling elements and transmits a rotational torque. In the left and right drive shafts, the numbers of the rolling elements provided in the sliding type constant velocity universal joints are different from each other. The fixed constant velocity universal joint comprises: an outer coupling member having a rolling groove formed on an inner peripheral surface; an inner coupling member having a rolling groove formed on an outer peripheral surface; a rolling element arranged between the rolling groove of the outer coupling member and the rolling groove of the inner coupling member and transmitting a rotational torque; and a retainer which retains the rolling element so as to be able to roll. In the left and right drive shafts, the numbers of the rolling elements included in the fixed type constant velocity universal joints are different from each other.

2. The power transmission mechanism according to claim 1, wherein: The driving source is an electric motor.

3. A vehicle, characterized in that: The vehicle includes the power transmission mechanism according to claim 1 or 2.

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