JP2021113606A - Power transmission device - Google Patents

Abstract

To provide a power transmission device that has a first power transmission shaft and a second power transmission shaft, which are connected with each other via a spline fitting portion, and that suppresses vibration and noise caused by axis run-out of the first power transmission shaft.SOLUTION: A first clearance of a first bearing 92a of a rotor shaft (first power transmission shaft) 44 is set to be smaller than a second clearance of a second bearing 96a of a gear shaft (second power transmission shaft) 42, so that at least a part of a radial load Fr applied to the gear shaft 42 at the time of power transmission is transmitted to the rotor shaft 44 via a spline fitting portion 46 and is received by a transformer axle case 60 via the first bearing 92a. As a result, both the gear shaft 42 and the rotor shaft 44 are rotated in a state of being pressed in a direction of action by the radial load Fr, and their axis run-out is suppressed to reduce vibration and noise.SELECTED DRAWING: Figure 3

Description

The present invention relates to a power transmission device, and more particularly to a technique for suppressing vibration and noise of a power transmission device having a first power transmission shaft and a second power transmission shaft connected via a spline fitting portion.

(a) A first power transmission shaft and a second power transmission shaft that are arranged adjacent to each other on one axis and are connected so as to be able to transmit power via a spline fitting portion at shaft ends on sides close to each other. A shaft, (b) a pair of first bearings arranged inside the first bearing holding portion of the support member and rotatably supporting the first power transmission shaft around the one axis, and (c) A power transmission device having a pair of second bearings arranged inside a second bearing holding portion of the support member and rotatably supporting the second power transmission shaft around the one axis is known. ing. The device described in Patent Document 1 is an example thereof, which relates to a power transmission device for a vehicle, in which the rotor shaft 44 corresponds to the first power transmission shaft and the gear shaft 42 corresponds to the second power transmission shaft. Patent Document 1 also describes a technique of providing a friction damper in the spline fitting portion in order to suppress rattling noise of the spline fitting portion.

Japanese Unexamined Patent Publication No. 2018-135934

However, although the friction damper can suppress rattling in the circumferential direction of the spline fitting portion by applying a predetermined frictional resistance in the rotational direction, the effect of suppressing rattling in the radial direction is small. Therefore, the first power transmission shaft connected to the second power transmission shaft via the spline fitting portion swings due to the radial backlash of the spline fitting portion, the misalignment of each part, and the like, and the first When the bearing load of the bearing or the second bearing fluctuates at a frequency including a high-order frequency component of the rotation speed, there is a problem that the load fluctuation is transmitted to the support member to generate vibration and noise. That is, when the second power transmission shaft is provided with a gear that transmits power to and from a member different from the first power transmission shaft, the reaction force during the power transmission causes the second power transmission shaft to reach the second power transmission shaft via the gear. Since a radial load is applied to the shaft, the second power transmission shaft is rotated while being pressed by the support member via the second bearing by the radial load, while the second power transmission shaft is connected to the second power transmission shaft via the spline fitting portion. Since the first power transmission shaft connected in the above direction is not affected by the radial load, the first power transmission shaft may be easily shaken during rotation.

The present invention has been made in the background of the above circumstances, and an object of the present invention is a power transmission device having a first power transmission shaft and a second power transmission shaft connected via a spline fitting portion. The purpose is to suppress vibration and noise generated due to the vibration of the first power transmission shaft.

In order to achieve this purpose, the present inventors have conducted various experiments and studies, and found that there is a correlation between vibration and noise and the runout of the first power transmission shaft, and in particular, the spline of the pair of first bearings. It was found that the load fluctuation of the 1st a bearing on the fitting portion side greatly affects the vibration and noise.
The present invention has been made based on such findings, and the first invention is (a) arranged adjacent to each other on one axis and via a spline fitting portion at the shaft end portion on the side close to each other. The first power transmission shaft and the second power transmission shaft that are connected so as to be able to transmit power, and (b) the first power transmission shaft that is arranged inside the first bearing holding portion of the support member and is connected to the one axis. A pair of first bearings that are rotatably supported around and (c) a second power transmission shaft that is arranged inside the second bearing holding portion of the support member so that the second power transmission shaft can rotate around the one axis. It has a pair of supporting second bearings, and (d) the second power transmission shaft is provided with gears that transmit power to and from a member different from the first power transmission shaft. In a power transmission device in which a radial load is applied to the second power transmission shaft via the gears by a reaction force during the power transmission, (e) of the pair of first bearings on the spline fitting portion side. The first clearance between the first power transmission shaft and the first bearing holding portion in the first a bearing is such that at least a part of the radial load is from the second power transmission shaft via the spline fitting portion. The second power transmission shaft in the second a bearing on the spline fitting portion side of the pair of second bearings so as to be transmitted to the first power transmission shaft and received by the support member via the first a bearing. It is characterized in that it is made smaller than the second clearance between the second bearing holding portion and the second bearing holding portion.

According to the second invention, in the power transmission device of the first invention, (a) an annular groove is provided on the outer peripheral surface of the outer ring of the second a bearing to dispose an annular elastic member, and a part of the elastic member is provided. It protrudes from the annular groove and is brought into close contact with the inner peripheral surface of the second bearing holding portion. It is characterized in that the protruding dimension of the elastic member protruding from the annular groove is reduced in the directional portion.

According to the third invention, in the power transmission device of the first invention, (a) an annular groove is provided on the outer peripheral surface of the outer ring of the second a bearing to dispose an annular elastic member, and a part of the elastic member is provided. It protrudes from the annular groove and is brought into close contact with the inner peripheral surface of the second bearing holding portion, and (b) the thickness of the elastic member on the acting direction side of the radial load is reduced, and the acting direction thereof. It is characterized in that the protruding dimension of the elastic member protruding from the annular groove is reduced in the side portion.

In such a power transmission device, the first clearance of the first a bearing on the spline fitting portion side of the pair of first bearings is the second clearance of the second a bearing on the spline fitting portion side of the pair of second bearings. It is smaller than the clearance, and at least a part of the radial load applied to the second power transmission shaft is transmitted from the spline fitting portion to the first power transmission shaft and received by the support member via the first a bearing. As a result, both the first power transmission shaft and the second power transmission shaft can be rotated in a state of being pressed in the direction of action by the radial load, and the first power transmission shaft and the second power transmission shaft thereof can be rotated. Since the runout of the shaft is suppressed, the vibration and noise generated by the load fluctuation including the high-order frequency component of the rotation speed due to the runout are transmitted to the support member via the first a bearing or the like is reduced. NS.

In the second invention, an annular groove is provided on the outer peripheral surface of the outer ring of the second a bearing to dispose an elastic member, and a part of the elastic member protrudes from the annular groove and comes into close contact with the inner peripheral surface of the second bearing holding portion. In this case, the friction of the elastic member suppresses the relative rotation between the outer ring and the second bearing holding portion, and the wear due to creep (sliding rotation) of the outer ring is suppressed. In that case, when the second clearance of the second a bearing is substantially eliminated by the elastic member, the radial load is received by the support member via the second a bearing and the elastic member, and the second power transmission shaft is abbreviated as one axis. It will be held concentrically, and the first power transmission shaft will be in a state where it is easy to swing. On the other hand, the groove depth of the portion of the annular groove on the acting direction side of the radial load is increased, and the protruding dimension of the elastic member protruding from the annular groove is reduced in the acting direction side portion of the annular groove. It is permissible to displace in the direction of action according to the radial load. As a result, at least a part of the radial load applied to the second power transmission shaft is transmitted to the first power transmission shaft via the spline fitting portion, and the first clearance is relatively small via the first a bearing. It is received by the support member, and the vibration and noise of the first power transmission shaft are suppressed and vibration and noise are reduced.

The third invention is a case where an annular groove is provided on the outer peripheral surface of the outer ring of the second a bearing and an elastic member is arranged, and wear due to creep of the outer ring is suppressed, but the first invention is the same as the second invention. The runout of the power transmission shaft may increase. On the other hand, the thickness of the portion of the elastic member on the acting direction side of the radial load is reduced, and the protruding dimension of the elastic member protruding from the annular groove is reduced in the acting direction side portion, so that the second a bearing has a radial load. Therefore, it is allowed to be displaced toward the action direction side. As a result, at least a part of the radial load applied to the second power transmission shaft is transmitted to the first power transmission shaft via the spline fitting portion, and the first clearance is relatively small via the first a bearing. It is received by the support member, and the vibration and noise of the first power transmission shaft are suppressed and vibration and noise are reduced.

It is a skeleton diagram explaining an example of the power transmission device for a vehicle to which this invention is applied. In the vehicle power transmission device of FIG. 1, a counter shaft arranged on the second axis S2, a rotor shaft (first power transmission shaft) and a gear shaft (second power) arranged on the third axis S3. It is a front view which concretely illustrated the transmission shaft). It is sectional drawing which specifically explains the support structure of the part near the spline fitting part in FIG. FIG. 3 is a cross-sectional view of the second bearing supporting the gear shaft cut at an annular groove portion where an O-ring is mounted. FIG. 4 is a cross-sectional view of the annular groove of the VV arrow-viewing portion in FIG. 4, which is shown together with the O-ring. FIG. 4 is a cross-sectional view of the annular groove of the VI-VI arrowhead portion in FIG. 4, which is shown together with the O-ring. It is a side view which looked at the 2nd bearing from the axial direction, and is the figure explaining the 2nd clearance C2 with the 2nd bearing holding part. FIG. 3 is a side view of the first bearing supporting the rotor shaft as viewed from the axial direction, and is a diagram for explaining the first clearance C1 with the first bearing holding portion. It is a figure explaining the turning pin and the like for positioning the phase around the 3rd axis S3 of the outer ring of the 2nd bearing, and is the side view corresponding to FIG. It is a figure explaining the large diameter fitting part and the like provided in the O-ring for positioning the phase around the 3rd axis S3 of the outer ring of the 2nd bearing, and is the side view corresponding to FIG. It is a figure explaining the case where the outer peripheral shape is elliptical shape in order to position the phase around the axis of the outer ring of the 2nd bearing, and is the side view corresponding to FIG. It is a figure explaining the result of having measured the noise using the product of this invention and the comparative products 1 and 2. It is a figure explaining another embodiment of this invention, and is the cross-sectional view corresponding to FIG. FIG. 13 is a cross-sectional view of the annular groove of the XIV-XIV arrow-viewing portion in FIG. 13, which is shown together with the O-ring. FIG. 13 is a cross-sectional view of the annular groove of the XV-XV arrow-viewing portion in FIG. 13, which is shown together with the O-ring. It is a figure explaining the mechanism that vibration and noise are generated by radial play of a spline fitting part.

The present invention is preferably applied to, for example, a power transmission device for a vehicle, but can also be applied to a power transmission device other than that for a vehicle. The present invention is suitable for, for example, a power transmission device for a vehicle such as an engine-driven vehicle or a hybrid-driven vehicle having an engine (internal combustion engine) as a driving force source, or an electric vehicle traveling by using an electric motor as a driving force source. Applies. For example, the first power transmission shaft is a rotor of a rotating machine such as an electric motor or a generator, and the second power transmission shaft is configured to transmit engine rotation or reverse input rotation from wheels via gears. Will be done. The spline fitting portion is composed of an inner spline tooth and an outer spline tooth meshed with the inner spline tooth. For example, an inner spline tooth is provided on the first power transmission shaft and an outer spline tooth is provided on the second power transmission shaft. However, the first power transmission shaft may be provided with outer spline teeth and the second power transmission shaft may be provided with inner spline teeth. That is, one of the inner spline tooth and the outer spline tooth may be provided on the first power transmission shaft, and the other may be provided on the second power transmission shaft. The second power transmission shaft is provided with a gear that transmits power to and from a member different from the first power transmission shaft. A helical gear is suitable as this gear, but a gear such as a spur gear, a bevel gear, or a hypoid gear may be provided.

Ball bearings are preferably used as the first bearing and the second bearing, but other bearings such as roller bearings can also be used. In these bearings, one of the inner ring and the outer ring is press-fitted (tightened) and the other is gap-fitted due to assembly. For example, the inner ring is press-fitted and fixed to the power transmission shaft, and the outer ring is gap-fitted to the bearing holding portion of the support member. good. When the outer ring is gap-fitted in the bearing holding portion, the outer ring may be worn by creep during power transmission. Therefore, especially for the second bearing to which a radial load is applied, an annular groove is provided in the outer ring to provide an elastic member. It is desirable to prevent creep by wearing it. In that case, it is desirable to devise the groove depth of the annular groove and the thickness of the elastic member to secure a second clearance on the portion on the side in the acting direction of the radial load. An O-ring is preferably used as the elastic member, but other elastic members can also be adopted. When the inner ring of the second bearing is gap-fitted to the second power transmission shaft, the inner ring may be worn by creep during power transmission. Therefore, an annular groove is provided in the second power transmission shaft to attach an elastic member. It is desirable to prevent creep between the inner ring and the inner ring. In that case as well, it is desirable to devise the groove depth of the annular groove and the thickness of the elastic member to secure a second clearance on the portion on the side in the acting direction of the radial load.

The first clearance and the second clearance are the total clearance dimensions including the gap between the bearing and the power transmission shaft, the gap between the bearing and the bearing holding portion, and the gap inside the bearing, but are press-fitted and fixed. Since the gap of the portion to be fitted is substantially 0, the gap of the portion to be fitted and the gap inside the bearing are the centers. Further, at least a part of the radial load applied to the second power transmission shaft is transmitted from the second power transmission shaft to the first power transmission shaft via the spline fitting portion, and the support member is transmitted via the first a bearing. The size of the first clearance and the second clearance should be adjusted in consideration of errors such as the coaxiality of the first power transmission shaft and the second power transmission shaft, the inclination of the shaft, and the roundness of each part. It is desirable to determine. The requirements for the magnitude relationship between the first clearance and the second clearance may be satisfied at least in the portion on the acting direction side of the radial load. As the support member provided with the bearing holding portion, for example, a case having a storage space for accommodating a power transmission shaft such as a transaxle case or a transmission case is suitable, but other support members may be used.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In the following examples, the drawings are appropriately simplified or modified for the sake of explanation, and the dimensional ratios and shapes of each part are not necessarily drawn accurately.

FIG. 1 is a skeleton diagram illustrating a vehicle power transmission device 10 to which the present invention is applied, and includes a power transmission mechanism 12. FIG. 1 is a developed view showing a plurality of axes constituting the power transmission mechanism 12 developed so as to be located in a common plane. The vehicle power transmission device 10 is a transaxle for a horizontal hybrid vehicle such as an FF vehicle in which a plurality of axes are arranged along the vehicle width direction, and is a transaxle of the first axis S1 to substantially parallel to the vehicle width direction. It has a 4-axis line S4. An input shaft 22 connected to the engine 16 via a damper device 18 is provided on the first axis S1, and a single pinion type planetary gear device 24 and a first motor concentric with the first axis S1. The generator MG1 is arranged. The planetary gear device 24 and the first motor generator MG1 function as an electric differential unit 26. The input shaft 22 is connected to the carrier 24c of the planetary gear device 24 which is a differential mechanism, and the first motor generator is connected to the sun gear 24s. The rotor shaft 28 of MG1 is connected, and the engine output gear 30 is provided on the ring gear 24r. The sun gear 24s and the ring gear 24r are meshed with a plurality of pinions 24p rotatably arranged on the carrier 24c.

The first motor generator MG1 is selectively used as an electric motor and a generator, and the rotation speed of the engine 16 is continuously controlled by continuous control of the rotation speed of the sun gear 24s by regenerative control or the like functioning as a generator. Is continuously changed and output from the engine output gear 30. Further, the torque of the first motor generator MG1 is set to 0 and the sun gear 24s is idled, so that the output from the engine 16 is cut off and the engine 16 is prevented from rotating during motor running or inertia running. Will be done. The engine 16 is an internal combustion engine such as a gasoline engine or a diesel engine that generates power by burning fuel, and is used as a driving force source for traveling. The input shaft 22 is connected to the oil pump 56 through the shaft center of the first motor generator MG1, and the oil pump 56 is rotationally driven by the engine 16.

A counter shaft 36 provided with a reduction gear 32 and a reduction gear 34 is rotatably arranged on the second axis S2, and the reduction gear 32 is meshed with the engine output gear 30. The reduction gear 32 is also meshed with a motor output gear 40 arranged on the third axis S3. The motor output gear 40 is provided on the gear shaft 42, and the gear shaft 42 transmits power via the rotor shaft 44 of the second motor generator MG2 arranged on the third axis S3 and the spline fitting portion 46. It is connected as possible. The second motor generator MG2 is selectively used as an electric motor and a generator, and is used as a driving force source for traveling by power running control so as to function as an electric motor. The vehicle power transmission device 10 is a multi-axis hybrid in which the second motor generator MG2 is arranged on the third axis S3, which is different from the first axis S1 in which the engine 16 and the electric differential unit 26 are arranged. It is a power transmission device for vehicles.

The reduction gear 34 is meshed with the differential gear 50 of the differential device 48 arranged on the fourth axis S4, and the driving force from the engine 16 and the second motor generator MG2 is left and right via the differential device 48. It is distributed to the drive shaft 52 of the above and is transmitted to the left and right drive wheels 54. The vehicle power transmission device 10 is a power transmission device, and in this embodiment, it is a transaxle having a differential device 48.

The vehicle power transmission device 10 includes a transaxle case 60 that is integrally fixed to the engine 16 and is supported by the vehicle body via a bracket or the like. The transaxle case 60 is composed of three case members, a front case member 62, an intermediate case member 64, and a rear cover 66, and abutting portions such as flanges provided at the end portions in the respective axial directions abut against each other. In the combined state, they are fastened by a large number of fastening bolts and integrally joined to each other. The front case member 62 has an opening that opens toward the engine 16 side integrally fixed to the engine 16, and a first accommodation space 72 for accommodating the damper device 18 is formed between the front case member 62 and the engine 16. .. The intermediate case member 64 is provided with a tubular outer cylinder 74 and a partition wall 76 provided in a posture substantially orthogonal to the first axis S1 to the fourth axis S4 so as to extend from the outer cylinder 74 toward the inner circumference side. A second accommodation space 78 for accommodating the electric differential portion 26, the counter shaft 36, the gear shaft 42, the differential device 48, and the like is provided between the front case member 62 and the partition wall 76. It is formed. The front case member 62 and the partition wall 76 include a support portion that rotatably supports the engine output gear 30, the counter shaft 36, the gear shaft 42, the differential device 48, and the like via bearings. Further, a third accommodation space 80 for accommodating the first motor generator MG1 and the second motor generator MG2 is formed between the rear cover 66 and the partition wall 76. The rear cover 66 and the partition wall 76 include a support portion that rotatably supports the rotor shafts 28 and 44 via bearings.

FIG. 2 is a front view that specifically illustrates the counter shaft 36 arranged on the second axis S2, the gear shaft 42 and the rotor shaft 44 arranged on the third axis S3, and the like. The motor-side power transmission unit 90 is composed of the rotor shaft 44, the gear shaft 42, and the counter shaft 36. The gear shaft 42 and the rotor shaft 44 are arranged adjacent to each other on the third axis S3, and are connected to each other so as to be able to transmit power via a spline fitting portion 46 at the shaft end portions on the side close to each other. There is. The end of the gear shaft 42 on the MG2 side of the second motor generator has a diameter smaller than that of the rotor shaft 44 and is fitted into the cylinder of the rotor shaft 44. An outer spline tooth 42t is provided on the outer peripheral surface of the fitting portion of the gear shaft 42, while an inner spline tooth 44t is provided on the inner peripheral surface of the fitting portion of the rotor shaft 44. The spline teeth 42t and the inner spline teeth 44t are meshed with each other. These outer spline teeth 42t and inner spline teeth 44t are composed of, for example, an involute spline having an involute tooth profile. The rotor shaft 44 and the gear shaft 42 are arranged adjacent to each other on the third axis S3, which is a single axis, and power can be transmitted via the spline fitting portion 46 at the shaft end portions on the side close to each other. Corresponds to the first power transmission shaft and the second power transmission shaft connected to. Further, the motor output gear 40 corresponds to a gear provided on the second power transmission shaft, and the motor output gear 40 and the reduction gear 32 are helical gears.

The rotor shaft 44 is rotatably supported by a transaxle case 60 around the third axis S3 via a pair of first bearings 92a, 92b. The rotor 94 of the second motor generator MG2 is connected to the central portion of the rotor shaft 44 in the axial direction so as not to rotate relative to each other. The first bearings 92a and 92b are arranged on both sides of the rotor 94 in the axial direction of the third axis S3 (the direction parallel to the third axis S3 and the left-right direction in FIG. 2), and are spline-fitted to the gear shaft 42. The first bearing 92a on the side of the vehicle is the first a bearing. The gear shaft 42 is rotatably supported by a transaxle case 60 around the third axis S3 via a pair of second bearings 96a, 96b. The second bearings 96a and 96b are arranged on both sides of the motor output gear 40 in the axial direction of the third axis S3, and the second bearing 96a on the side spline-fitted to the rotor shaft 44 is the second a bearing. The gear shaft 42 functions as a drive shaft that transmits the power of the second motor generator MG2 to the counter shaft 36 to rotationally drive the drive wheels 54, and also powers the engine 16 from the counter shaft 36 via the motor output gear 40, etc. Is transmitted. In addition, reverse input rotation (driven rotation) is transmitted from the drive wheels 54 to the gear shaft 42 via the differential device 48 and the counter shaft 36 during coasting or the like.

The spline fitting portion 46 has fitting play (play in the circumferential direction and the radial direction) due to the runout of the tooth groove or the like. Therefore, due to the relative rotation fluctuations of the gear shaft 42 and the rotor shaft 44 due to the torque fluctuation caused by the explosion of the engine 16, the outer spline teeth 42t and the inner spline teeth 44t repeatedly separate and collide with each other to make rattling noise. (Gearing noise) may occur. In order to suppress the occurrence of such rattling noise, in this embodiment, the friction damper 47 is arranged in the portion adjacent to the spline fitting portion 46. Specifically, the gear shaft 42 is provided with a cylindrical outer peripheral surface in the axial direction inside the portion where the outer spline teeth 42t are provided, and the rotor shaft 44 is provided from the portion where the inner spline teeth 44t are provided. The inner peripheral surface of the cylinder is provided on the outer side in the axial direction, that is, on the tip end side, and the friction damper 47 is arranged in the annular space between the outer peripheral surface of the cylinder and the inner peripheral surface of the cylinder. The friction damper 47 is mainly composed of an elastic member such as rubber, is fixed to one member via a cylindrical metal fitting or the like, and is pressed by the other member to compress and deform the elastic member, thereby causing sliding friction. The rattling noise is reduced by the buffering action of the frictional resistance.

FIG. 3 is a cross-sectional view specifically explaining the support structure of the portion in the vicinity of the spline fitting portion 46 in FIG. In FIG. 3, the first bearing 92a is a ball bearing, which is arranged and held inside the cylindrical first bearing holding portion 100a provided on the transaxle case 60. The first bearing holding portion 100a is integrally provided with the partition wall 76. In this embodiment, the inner ring 102a of the first bearing 92a is press-fitted and fixed to the rotor shaft 44, and the outer ring 104a is gap-fitted to the first bearing holding portion 100a. Although not shown, the other first bearing 92b is also attached in the same manner as the first bearing 92a. Further, the second bearings 96a and 96b are both ball bearings, and are arranged and held inside the cylindrical second bearing holding portions 106a and 106b provided in the transaxle case 60, respectively. The second bearing holding portion 106a is integrally provided with the partition wall 76, and the second bearing holding portion 106b is integrally provided with the front case member 62. In this embodiment, the inner rings 108a and 108b of the second bearings 96a and 96b are press-fitted and fixed to the gear shaft 42, and the outer rings 110a and 110b are gap-fitted to the second bearing holding portions 106a and 106b. The transaxle case 60 provided with the first bearing holding portion 100a and the second bearing holding portions 106a and 106b corresponds to a support member.

By fitting the outer rings 110a and 110b of the second bearings 96a and 96b in a gap, a predetermined second clearance C2 (FIG. 7) is formed. The second clearance C2 is a clearance between the gear shaft 42 and the second bearing holding portions 106a and 106b, and is mainly a gap between the outer rings 110a and 110b and the second bearing holding portions 106a and 106b. It includes a backlash dimension due to a gap inside the bearings 96a and 96b, that is, a gap between the inner rings 108a and 108b and the ball, and a gap between the outer rings 110a and 110b and the ball. Similarly to the second bearings 96a and 96b, the first bearing 92a also has a predetermined first clearance C1 (see FIG. 8) formed between the outer ring 104a and the inner peripheral surface of the first bearing holding portion 100a. The other first bearing 92b also has a predetermined first clearance C1 like the first bearing 92a. FIG. 7 is a side view of the second bearing 96a viewed from the axial direction of the third axis S3, and FIG. 8 is a side view of the first bearing 92a viewed from the axial direction of the third axis S3.

By the way, when power is transmitted between the motor output gear 40 and the reduction gear 32, a radial load Fr is applied to the gear shaft 42 via the motor output gear 40 due to the reaction force during the power transmission. Is applied with a load in a direction away from the counter shaft 36 as shown in FIG. Therefore, the gear shaft 42 is pressed in the direction of action of the radial load Fr (upward in FIG. 2 in the direction of the arrow Fr), and the second bearings 96a and 96b supporting the gear shaft 42 are also of the radial load Fr. Pressed in the direction of action. At this time, the second bearings 96a and 96b generate creep in which the outer rings 110a and 110b rotate relative to the second bearing holding portions 106a and 106b due to the presence of the second clearance C2, and the outer peripheral surfaces of the outer rings 110a and 110b are formed. May wear. In order to prevent this, in this embodiment, a pair of annular grooves 112 (see FIG. 4) are provided on the outer peripheral surfaces of the outer rings 110a and 110b, respectively, and an O-ring 114 is arranged as an elastic member. A part of the O-ring 114 protrudes outward from the annular groove 112, is brought into close contact with the inner peripheral surfaces of the second bearing holding portions 106a and 106b as shown in FIG. 5, and is pressed by its own elasticity. The creep of the outer rings 110a and 110b is suppressed by the friction between the second bearing holding portions 106a and 106b. FIG. 5 is a cross-sectional view of the annular groove 112 of the VV arrow-viewing portion in FIG. 4, which is shown together with the O-ring 114.

When the O-ring 114 is attached to the outer rings 110a and 110b of the second bearings 96a and 96b in this way, the gear shaft 42 is suppressed from being displaced in the acting direction of the radial load Fr during power transmission, and the third axis S3 and the third axis S3. Held almost concentrically. On the other hand, when the motor output gear 40 is rotationally driven by the engine 16 via the reduction gear 32, the rotor shaft 44 and the gear shaft 42 via the spline fitting portion 46 as shown in FIG. 16A. It can be rotated. At this time, there is a possibility that the spline fitting portion 46 may rattle due to the torque fluctuation of the engine 16. Further, the core of the gear shaft 42 and the spline fitting portion 46 is also during EV traveling in which the second motor generator MG2 is used as a driving force source and in power generation traveling in which the second motor generator MG2 is regeneratively controlled to generate power. Rattling at the spline fitting portion 46 due to misalignment, misalignment between the rotor shaft 44 and the spline fitting portion 46, non-uniformity of the meshing pitch circle of the spline fitting portion 46 (oval, etc.), etc. It can occur. In this embodiment, the friction damper 47 suppresses rattling in the circumferential direction, but there is a possibility that rattling in the radial direction may occur due to the fitting backlash in the radial direction. Since the gear shaft 42 is held substantially concentrically with the third axis S3, if the first clearance C1 of the first bearing 92a is relatively large and the rotor shaft 44 can be displaced in the radial direction, the spline fits. Radial rattling occurs at the joint 46. When the backlash in the radial direction occurs in this way, the rotor shaft 44 swings at a frequency including a high-order frequency component of the rotation speed as shown in FIG. 16 (b). The larger the radial backlash of the spline fitting portion 46, or the larger the misalignment between the gear shaft 42 or the rotor shaft 44 and the spline fitting portion 46, the larger the swing width of the center runout of the rotor shaft 44. Then, due to the runout of the rotor shaft 44, as shown in FIG. 16 (c), the bearing loads Fb of the first bearings 92a and 92b and the second bearings 96a and 96b generate high-order frequency components of the rotation speed. It fluctuates in the cycle including, and vibration and noise are generated by transmitting this bearing load Fb to the trans-axle case 60. The amount of fluctuation of the bearing load Fb is such that the larger the swing width of the rotor shaft 44, that is, the larger the radial backlash of the spline fitting portion 46, or the misalignment between the gear shaft 42 or the rotor shaft 44 and the spline fitting portion 46. When is large, it becomes large, and vibration and noise also become large. According to experiments by the present inventors, the amount of fluctuation of the bearing load Fb of the first bearing 92a is particularly large, which greatly affects vibration and noise.

On the other hand, in this embodiment, with respect to at least the second bearing 96a of the pair of second bearings 96a and 96b of the gear shaft 42, as shown in FIG. 4, the portion of the annular groove 112 on the acting direction side of the radial load Fr. Is provided with a deep groove portion 112r in which the groove depth gradually increases, and the protrusion dimension of the O-ring 114 protruding from the annular groove 112 is reduced in the deep groove portion 112r. In this embodiment, as shown in FIG. 6, the protruding dimension of the O-ring 114 is set to substantially 0, and the second clearance C2 is formed between the outer ring 110a and the second bearing holding portion 106a. As a result, the gear shaft 42 is allowed to be displaced together with the second bearing 96a by the second clearance C2 in the acting direction of the radial load Fr. Even when the O-ring 114 protrudes from the deep groove portion 112r, it is sufficient that the second clearance C2 can be substantially secured by the elastic deformation of the O-ring 114. Regarding the other second bearing 96b, it is not always necessary to increase the groove depth of the portion on the acting direction side, and the groove depth may be the same as that in FIG. 5 over the entire circumference of the annular groove 112, but the second bearing 96a Similarly, the deep groove portion 112r may be provided on the portion on the acting direction side of the radial load Fr. FIG. 6 is a cross-sectional view of the annular groove 112 of the VI-VI arrow-viewing portion in FIG. 4, that is, a cross-sectional view of the portion provided with the deep groove portion 112r, which is shown together with the O-ring 114.

On the other hand, the first clearance C1 in the first bearing 92a is made smaller than the second clearance C2 in the second bearing 96a. As a result, when the gear shaft 42 is displaced in the acting direction of the radial load Fr according to the radial load Fr, and the rotor shaft 44 is also displaced in the acting direction of the radial load Fr via the spline fitting portion 46, the gear shaft 42 is displaced in the acting direction of the radial load Fr. The first bearing 92a is brought into contact with the first bearing holding portion 100a before the second bearing 96a is brought into contact with the second bearing holding portion 106a, and at least a part of the radial load Fr is passed through the first bearing holding portion 100a. It will be received by the transformer axle case 60. In this way, when the first bearing 92a is brought into contact with the first bearing holding portion 100a by the action of the radial load Fr, the radial backlash in the spline fitting portion 46 is suppressed and the center of the rotor shaft 44 is suppressed. Runout is suppressed. As a result, the load fluctuation transmitted to the transaxle case 60 via the first bearing 92a or the like is suppressed due to the center swing of the rotor shaft 44, and the vibration generated from the transaxle case 60 due to the load fluctuation is suppressed. And noise are reduced. The first clearance C1 and the second clearance C2 have the coaxiality and inclination of the rotor shaft 44 and the gear shaft 42 so that the first bearing 92a is brought into contact with the first bearing holding portion 100a by the action of the radial load Fr. It is determined in consideration of the error of each part such as.

In this case, the phase of the outer ring 110a of the second bearing 96a around the third axis S3 is set so that the deep groove portion 112r of the annular groove 112 of the second bearing 96a is reliably located on the acting direction side of the radial load Fr. It is necessary to position the bearing holding portion 106a. For example, when the outer ring 110a is non-rotatably positioned with respect to the second bearing holding portion 106a by the O-ring 114, the marks 116 and 118 are placed on the outer ring 110a and the second bearing holding portion 106a as shown in FIG. It may be provided, aligned and assembled so that the marks 116 and 118 match. As shown in FIG. 9, the turning pin 120 is provided so as to project from the outer peripheral surface of the outer ring 110a, and the positioning groove 122 is provided in the second bearing holding portion 106a, and the turning pin 120 is inserted into the positioning groove 122. You may also align and assemble as follows. As shown in FIG. 10, a large groove portion 124 having a large depth and width is provided in a part of the annular groove 112, a positioning groove 126 is provided in the second bearing holding portion 106a, and a large diameter fitting provided in the O-ring 114. With the joint portion 128 fitted in the large groove portion 124, the large diameter fitting portion 128 may be aligned and assembled so as to be inserted into the positioning groove 126. Further, as shown in FIG. 11, the outer peripheral shape of the outer ring 110a is elliptical, and the inner peripheral shape of the second bearing holding portion 106a is elliptical, so that the phase of the outer ring 110a around the third axis S3 is positioned. You can also.

As described above, the motor-side power transmission unit 90 of the vehicle power transmission device 10 of the present embodiment includes the gear shaft 42 and the rotor shaft 44 connected via the spline fitting portion 46, and at the time of power transmission. A radial load Fr is applied to the gear shaft 42 via the motor output gear 40 by the reaction force of. In that case, the first clearance C1 of the first bearing 92a on the spline fitting portion 46 side of the pair of first bearings 92a and 92b of the rotor shaft 44 is the pair of second bearings 96a and 96b of the gear shaft 42. It is smaller than the second clearance C2 of the second bearing 96a on the spline fitting portion 46 side, and at least a part of the radial load Fr applied to the gear shaft 42 during power transmission is from the spline fitting portion 46 to the rotor shaft 44. Is transmitted to and received by the trans-axle case 60 via the first bearing 92a. As a result, both the gear shaft 42 and the rotor shaft 44 can be rotated in a state of being pressed in the acting direction by the radial load Fr, and the runout of the gear shaft 42 and the rotor shaft 44 is suppressed. Therefore, the vibration and noise generated by the load fluctuation including the high-order frequency component of the rotation speed being transmitted to the trans-axle case 60 via the first bearing 92a and the like due to the center swing are reduced.

Further, in this embodiment, an annular groove 112 is provided on the outer peripheral surface of the outer ring 110a of the second bearing 96a to dispose of an O-ring 114, and a part of the O-ring 114 protrudes from the annular groove 112 to hold the second bearing. Since the portion 106a is brought into close contact with the inner peripheral surface, the relative rotation between the outer ring 110a and the second bearing holding portion 106a is suppressed by the friction of the O-ring 114, and the wear of the outer ring 110a due to creep is suppressed. In that case, when the second clearance C2 of the second bearing 96a is substantially eliminated by the O-ring 114, the radial load Fr is received by the transaxle case 60 via the second bearing 96a and the O-ring 114, and the gear shaft. The 42 is held substantially concentrically with the third axis S3, and the rotor shaft 44 is in a state where it is easy to swing. On the other hand, in this embodiment, the groove depth of the portion of the annular groove 112 on the acting direction side of the radial load Fr is increased, and the protrusion dimension of the O-ring 114 protruding from the annular groove 112 is reduced in the acting direction side portion. Therefore, it is permissible for the second bearing 96a to be displaced toward its acting direction according to the radial load Fr. As a result, at least a part of the radial load Fr applied to the gear shaft 42 is transmitted from the spline fitting portion 46 to the rotor shaft 44, and the first clearance C1 is relatively small via the first bearing 92a. It is received by the axle case 60, and the vibration and noise of the rotor shaft 44 are suppressed and vibration and noise are reduced.

FIG. 12 is a diagram showing a comparison of the results of examining the noise generated from the transaxle case 60 by preparing the product of the present invention and the comparative products 1 and 2. The product of the present invention is the vehicle power transmission device 10 of the present embodiment. The comparative products 1 and 2 are the case where the deep groove portion 112r is not provided in the annular groove 112 of the second bearing 96a in the vehicle power transmission device 10, and the second clearance C2 is provided by the O-ring 114 over the entire circumference. Is substantially eliminated, and the gear shaft 42 is held substantially concentrically with the third axis S3 regardless of the radial load Fr. Further, the comparative product 1 is provided with the friction damper 47, but the comparative product 2 is the case where the friction damper 47 is not provided. Then, by connecting a motor instead of the drive wheel 54 and rotationally driving the left and right drive shafts 52, the second motor generator MG2 is experimentally reproduced to generate power by regenerative control, and the rotor shaft 44 The noise generated from the transaxle case 60 was measured so as to be rotated together with the gear shaft 42 via the spline fitting portion 46. In this case, since the engine 16 is stopped, the noise generated by the runout of the rotor shaft 44 can be appropriately measured.

As is clear from the results of FIG. 12, in the comparative product 2 without the friction damper 47, the load fluctuation including the high-order frequency component of the rotation speed is transmitted to the transaxle case 60 due to the center vibration of the rotor shaft 44. Not only that, the loudest noise is generated due to the rattling noise of the spline fitting portion 46 in the circumferential direction. In the comparative product 2, the presence of the friction damper 47 suppresses the generation of rattling noise in the circumferential direction of the spline fitting portion 46, so that the noise is reduced as compared with the comparative product 2. In the product of the present invention, the deep groove portion 112r is provided on the portion of the annular groove 112 on the acting direction side of the radial load Fr, and the second bearing 96a is allowed to be displaced on the acting direction side of the radial load Fr. At least a part of the load Fr is transmitted to the rotor shaft 44, the vibration of the rotor shaft 44 is suppressed, and the noise is minimized. The broken line Ln in FIG. 12 is the noise level when the backlash of the spline fitting portion 46 is reduced by high-precision processing, and the product of the present invention is lower than the noise level Ln. In other words, while processing the spline fitting portion 46 by a simple and inexpensive processing method, the noise generated due to the fitting backlash of the spline fitting portion 46 is reduced to the noise level Ln or less during high-precision machining. I was able to do it.

In the above embodiment, the deep groove portion 112r is provided in the annular groove 112 of the second bearing 96a, so that the second clearance C2 is secured in the portion on the acting direction side of the radial load Fr. As shown, it is also possible to provide a small diameter portion 114r on the O-ring 114 to secure a second clearance C2 on the portion on the acting direction side of the radial load Fr. 13 to 15 are views corresponding to FIGS. 4 to 6, and FIG. 13 is a cross-sectional view cut at a portion where the annular groove 112 is provided. FIG. 14 is a cross-sectional view of the annular groove 112 of the XIV-XIV arrow-viewing portion in FIG. 13, which is shown together with the O-ring 114. FIG. 15 is a cross-sectional view of the annular groove 112 of the XV-XV arrow-viewing portion in FIG. 13, which is shown together with the small diameter portion 114r of the O-ring 114.

Also in this embodiment, the second bearing 96a is radial by providing the small diameter portion 114r on the acting direction side portion of the radial load Fr of the O-ring 114 and ensuring the second clearance C2 on the acting direction side portion. It is permissible to displace the load Fr in the direction of action. As a result, at least a part of the radial load Fr is transmitted to the rotor shaft 44 and is received by the transaxle case 60 via the first bearing 92a, so that the same effect as that of the above embodiment can be obtained.

Further, in the above embodiment, the outer rings 110a and 110b of the second bearings 96a and 96b are provided with the annular groove 112 and the O-ring 114 is mounted. However, even when the annular groove 112 and the O-ring 114 are not provided, the rotor shaft 44 The first clearance C1 of the first bearing 92a is made smaller than the second clearance C2 of the second bearing 96a of the gear shaft 42, and at least a part of the radial load Fr applied to the gear shaft 42 during power transmission is the rotor shaft. If the transmission is transmitted to the 44 and is received by the trans-axle case 60 via the first bearing 92a, the center swing of the rotor shaft 44 can be suppressed and vibration and noise can be reduced, which is the same effect as in the above embodiment. Is obtained.

Although the examples of the present invention have been described in detail with reference to the drawings, these are merely embodiments, and the present invention is carried out in a mode in which various modifications and improvements are made based on the knowledge of those skilled in the art. be able to.

10: Vehicle power transmission device (power transmission device) 40: Motor output gear (gear) 42: Gear shaft (second power transmission shaft) 44: Rotor shaft (first power transmission shaft) 46: Spline fitting part 60: Trans axle case (support member) 92a: 1st bearing (1st a bearing) 92b: 1st bearing 96a: 2nd bearing (2nd a bearing) 96b: 2nd bearing 100a: 1st bearing holding portion 106a, 106b: 2nd Bearing holding part 110a: Outer ring 112: Circular groove 114: O-ring (elastic member) S3: Third axis (single axis) Fr: Radial load C1: First clearance C2: Second clearance

Claims (3)

The first power transmission shaft and the second power transmission shaft, which are arranged adjacent to each other on one axis and are connected so as to be able to transmit power via a spline fitting portion at the shaft end portions on the side close to each other
A pair of first bearings arranged inside the first bearing holding portion of the support member and rotatably supporting the first power transmission shaft around the one axis.
A pair of second bearings arranged inside the second bearing holding portion of the support member and rotatably supporting the second power transmission shaft around the one axis.
The second power transmission shaft is provided with a gear for transmitting power to and from a member different from the first power transmission shaft, and the reaction force at the time of the power transmission causes the gear to pass through the gear. In the power transmission device in which a radial load is applied to the second power transmission shaft.
Of the pair of first bearings, at least a part of the radial load is the first clearance between the first power transmission shaft and the first bearing holding portion in the first a bearing on the spline fitting portion side. The spline of the pair of second bearings is transmitted from the second power transmission shaft to the first power transmission shaft via the spline fitting portion and received by the support member via the first a bearing. A power transmission device characterized in that it is made smaller than the second clearance between the second power transmission shaft and the second bearing holding portion in the second a bearing on the fitting portion side. An annular groove is provided on the outer peripheral surface of the outer ring of the second bearing, and an annular elastic member is arranged. A part of the elastic member protrudes from the annular groove and forms an inner peripheral surface of the second bearing holding portion. As well as being in close contact
The claim is characterized in that the groove depth of the portion of the annular groove on the acting direction side of the radial load is increased, and the protruding dimension of the elastic member protruding from the annular groove is reduced in the acting direction side portion. The power transmission device according to 1. An annular groove is provided on the outer peripheral surface of the outer ring of the second bearing, and an annular elastic member is arranged. A part of the elastic member protrudes from the annular groove and forms an inner peripheral surface of the second bearing holding portion. As well as being in close contact
1. The elastic member is characterized in that the thickness of the portion on the acting direction side of the radial load is reduced, and the protruding dimension of the elastic member protruding from the annular groove is reduced in the portion on the acting direction side. The power transmission device described in.

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