JP2010196793A - Friction transmission device and driving force distribution device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction transmission device and a driving force distribution device using the same, capable of restraining reduction in durability of a roller friction surface, by minimizing deformation of a contact surface with a first roller of a second roller. <P>SOLUTION: This friction transmission device includes the first roller 31 and the second roller 32, bearing supports 23 and 25 for receiving reaction generated by pressing contact in the radial direction between the rollers, crankshafts 51L and 51R having a rotary shaft offset to an output shaft 13 being a rotary shaft of the second roller 32, a pair of bearings 52L and 52R for supporting the output shaft 13 by the crankshafts 51L and 51R, a pair of bearings 53L and 53R for supporting eccentric outer peripheral parts 51Lb and 51Rb being the rotary shaft of the crankshafts 51L and 51R by the bearing supports 23 and 25, and an inter-roller pressing force control motor 45 for changing a pressing contact state in the radial direction between the rollers by rotating the crankshafts 51L and 51R. The length W1 in the axial direction of the bearings 52L and 52R is set longer than the length W2 in the axial direction of the bearings 53L and 53R. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a friction transmission device and a driving force distribution device using the same.

  Conventionally, in a friction transmission device, power is transmitted with a torque capacity corresponding to the radial pressing contact state between the rollers by indirect radial pressing contact between the first roller and the second roller. Both rollers are supported by a common support plate and accommodated in the housing to prevent the reaction force generated by the radial pressing contact between the rollers from being transmitted to the housing. An example of a technique related to the above description is described in Patent Document 1.

  In this type of friction transmission device, in order to make the transmission torque capacity variable, it is necessary to change the radial pressing force between the rollers. For example, by supporting the second roller on the eccentric member and rotating the eccentric member, the second roller can be displaced in the radial direction relative to the first roller, and the radial pressing force between the rollers can be changed.

JP 2002-349653 A

  When the above configuration is adopted, the second roller is supported on the eccentric member by the inner bearing, and the eccentric member is supported on the support plate by the outer bearing. That is, the rotating shaft of the second roller is supported by the support plate by the radial double bearing. For this reason, since the bearing has low support rigidity with respect to the bending of the rotating shaft, the double shaft increases the bending of the rotating shaft, and the axial end of the second roller contact surface of the second roller toward the first roller side. There is a problem in that the roller friction surface is deteriorated in durability due to the large deformation and the radial pressing force between the rollers being biased to a part of the roller contact surface.

  An object of the present invention is to provide a friction transmission device that can suppress deformation of the contact surface of the second roller with the first roller and reduce the durability of the roller friction surface, and a driving force distribution device using the friction transmission device. is there.

  In the present invention, the axial length of the inner bearing that supports the rotating shaft of the second roller on the eccentric member is set longer than the axial length of the outer bearing that supports the rotating shaft of the eccentric member on the rotation support plate.

  Therefore, in the present invention, by increasing the axial length of the inner bearing, the support rigidity of the inner bearing with respect to the deflection of the rotating shaft is increased. Therefore, the contact surface of the second roller with the first roller is deformed. It is possible to reduce the durability of the roller friction surface.

It is a top view which shows the outline of the power train of the four-wheel drive vehicle of Example 1 to which the driving force distribution apparatus of this invention is applied. 1 is a longitudinal sectional view of a driving force distribution device 1 according to Embodiment 1. FIG. 1 is a side view of a driving force distribution device 1 according to Embodiment 1. FIG. 1 is an enlarged view of a main part of a driving force distribution device 1 according to a first embodiment. FIG. 6 is an enlarged view of a main part of a driving force distribution device 1 according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described based on examples shown in the drawings.

First, the configuration will be described.
(Configuration of power train)
FIG. 1 is a plan view schematically showing a power train of a four-wheel drive vehicle according to a first embodiment to which a driving force distribution device (friction transmission device) of the present invention is applied. The four-wheel drive vehicle of FIG. 1 is a base vehicle based on a rear-wheel drive vehicle in which rotation from the engine 2 is changed by the transmission 3 and then transmitted to the left and right rear wheels 6L and 6R via the rear propeller shaft 4 and the rear final drive unit 5. A part of the torque to the left and right rear wheels (main drive wheels) 6L, 6R is transferred from the drive force distribution device 1 to the left and right front wheels (secondary drive wheels) 9L, 9R via the front propeller shaft 7 and the front final drive unit 8. By transmitting, four-wheel drive traveling is enabled.

  The driving force distribution device 1 distributes a part of the torque to the left and right rear wheels 6L, 6R to the left and right front wheels 9L, 9R, and outputs it, thereby distributing the torque between the left and right rear wheels 6L, 6R and the left and right front wheels 9L, 9R. In the first embodiment, the driving force distribution device 1 is configured as shown in FIG.

(Configuration of driving force distribution device)
In FIG. 2, reference numeral 11 denotes a housing, and an input shaft 12 and an output shaft 13 are arranged in parallel with each other in the housing 11.
The input shaft 12 is rotatably supported with respect to the housing 11 by ball bearings 14 and 15 at both ends thereof, and the input shaft 12 is further rotatable with respect to the housing 11 by roller bearings 18 and 19 disposed in the housing 11. To support.

The roller bearings 18 and 19 are respectively held in bearing supports (rotary support plates) 23 and 25, and these bearing supports 23 and 25 are attached to corresponding inner side surfaces of the housing 11 by any means such as bolts (not shown). To wear.
Both ends of the input shaft 12 protrude from the housing 11 under liquid-tight sealing by seal rings 27 and 28, and the left end of the input shaft 12 in the figure is coupled to the output shaft of the transmission 3 (see FIG. 1). The middle right end is coupled to the rear final drive unit 5 via the rear propeller shaft 4 (see FIG. 1).

In the middle of the input shaft 12 in the axial direction, the first roller 31 is concentrically and integrally formed. In the middle of the output shaft 13 in the axial direction, the second roller 32 is concentrically and integrally formed. The first roller 31 and the second roller 32 are disposed in a common axis perpendicular plane.
The output shaft 13 is supported rotatably relative to the housing 11 by the following configuration.
That is, the crankshafts (eccentric members) 51L and 51R that are hollow on both ends of the output shaft 13 are loosely fitted on both sides in the axial direction of the second roller 32 integrally formed in the middle of the output shaft 13 in the axial direction.

The output shaft 13 is inserted through bearings (inner bearings) 52L and 52R in the loose fitting portions between the center holes 51La and 51Ra (radius is shown by Ri) of the crankshafts 51L and 51R and both ends of the output shaft 13. crankshafts 51L, the center hole 51La of 51R, in 51Ra, supports that can freely rotate around these central axis O _2.

As shown in FIG. 3, the crankshafts 51L and 51R are provided with eccentric outer peripheral portions 51Lb and 51Rb (radius is indicated by Ro) that are eccentric with respect to the center holes 51La and 51Ra (the central axis O ₂ ). The center axis O ₃ of the parts 51Lb and 51Rb is offset from the axis O ₂ of the center holes 51La and 51Ra (the rotation axis of the second roller 32) by an eccentricity ε between them.

  The eccentric outer peripheral portions 51Lb and 51Rb of the crankshafts 51L and 51R are rotatably supported in bearing supports 23 and 25 on the corresponding side via bearings (outer bearings) 53L and 53R. At this time, the crankshafts 51L and 51R Are positioned in the axial direction by thrust bearings 54L and 54R together with the second roller 32.

  As shown in FIG. 4, in the first embodiment, the axial length W1 of the bearings 52L and 52R is set longer than the axial length W2 of the bearings 53L and 53R. In the first embodiment, the bearing support span S1 of the bearings 52L and 52R is set shorter than the bearing support span S2 of the bearings 53L and 53R. Here, the bearing support span refers to the distance between the axial centers of a pair of bearings.

Ring gears 51Lc and 51Rc of the same specification are provided integrally with the eccentric outer peripheral portions 51Lb and 51Rb at the adjacent ends of the crankshafts 51L and 51R that face each other. Mesh. In this engagement, the crankshaft drive pinion 55 is engaged with the ring gears 51Lc and 51Rc in a state where the crankshafts 51L and 51R are in a rotational position where the eccentric outer peripheral portions 51Lb and 51Rb are aligned with each other in the circumferential direction. .
The crankshaft drive pinion 55 is coupled to the pinion shaft 56, and both ends of the pinion shaft 56 are rotatably supported on the housing 11 by bearings 56a and 56b.

The right end of the pinion shaft 56 on the right side of FIG. 2 is exposed to the outside of the housing 11, and the exposed end surface of the pinion shaft 56 is a pressing force control motor between rollers (attached to the housing 11). ) Drive-couple 45 output shafts 45a by serration fitting or the like.
Therefore, when the rotational position of the crankshafts 51L and 51R is controlled by the inter-roller pressing force control motor 45 via the pinion 55 and the ring gears 51Lc and 51Rc, the rotational axis O ₂ of the output shaft 13 and the second roller 32 is indicated by a broken line in FIG. It turns along the locus circle α shown.

The rotation of the rotational axis O ₂ changes the distance L1 between the roller axes of the first roller 31 and the second roller 32 (see FIG. 2), and the radial pressing force of the second roller 32 against the first roller 31 (between the rollers) The roller transmission torque capacity) can be arbitrarily controlled between 0 and the maximum value.
Accordingly, the inter-roller pressing force control motor 45, the pinion 55, and the crankshafts 51L and 51R together with the bearing supports 23 and 25 constitute the second roller turning means in the present invention.

  The crankshaft 51L and the output shaft 13 protrude from the housing 11 on the left side of FIG. 2, respectively, and a seal ring 57 is interposed between the housing 11 and the crankshaft 51L at the protruding portion, and a seal is provided between the crankshaft 51L and the output shaft 13. The ring 58 is interposed, and the seal rings 57 and 58 are used to liquid-tightly seal the crankshaft 51L protruding from the housing 11 and the protruding portion of the output shaft 13, respectively.

When the seal rings 57 and 58 are interposed, the centers of the inner and outer diameters are decentered in the same manner as the support position of the output shaft 13 at the end of the crankshaft 51L where the seal rings 57 and 58 are located. With such a seal structure, the output shaft 13 can be satisfactorily sealed at a location where the output shaft 13 protrudes from the housing 11 even though the rotation axis O ₂ is swung and displaced due to the above-described swiveling of the output shaft 13 and the second roller 32. Can continue.

(Torque distribution control)
Next, driving force distribution control according to the first embodiment will be described.
On the other hand, torque from the transmission 3 (see FIG. 1) to the input shaft 12 is directly transmitted from the input shaft 12 to the left and right rear wheels 6L and 6R via the rear propeller shaft 4 and the rear final drive unit 5 (both see FIG. 1). Is done.

  On the other hand, the driving force distribution device 1 according to the first embodiment controls the rotational position of the crankshafts 51L and 51R via the pinion 55 and the ring gears 51Lc and 51Rc by the inter-roller pressing force control motor 45, and sets the roller shaft distance L1 to the first. When the roller 31 and the second roller 32 are smaller than the sum of the radii, the rollers 31 and 32 have a roller transmission torque capacity corresponding to the radial mutual pressing force. Part of the torque to 6L and 6R can be directed from the first roller 31 to the output shaft 13 via the second roller 32.

  Thereafter, this torque is transmitted from the left end of the output shaft 13 in FIG. 2 to the left and right front wheels (slave drive wheels) 9L and 9R via the front propeller shaft 7 (see FIG. 1) and the front final drive unit 8 (see FIG. 1). The This enables four-wheel drive running in which both the left and right rear wheels 6L and 6R and the left and right front wheels 9L and 9R are driven.

In addition, during the inter-roller radial direction mutual pressure control (roller roller transmission torque capacity control) by the inter-roller pressing force control motor 45, the output shaft 13 and the second roller 32 (its rotation axis O ₂ ) are moved around the eccentric axis O ₃ . Rotating displacement. However, the turning displacement of the output shaft 13 and the second roller 32 (its rotation axis O ₂ ) can be absorbed by the universal joint connecting the output shaft 13 and the front propeller shaft 7, and the above left and right front wheels can be obtained without an eccentric joint. (Slave drive wheel) Torque transmission to 9L, 9R is not hindered.

Next, the operation of the first embodiment will be described.
[Deterioration of durability of roller friction surface due to deflection of output shaft]
In the driving force distribution device 1, the output shaft 13 that is the rotating shaft portion of the second roller 32 has a smaller transmission torque than the input shaft 12 that is the rotating shaft portion of the first roller 31. From this point of view, it is possible to reduce the outer diameter with respect to the input shaft 12.

  At this time, as the output shaft 13 is made thinner, the amount of deflection of the output shaft 13 increases and the durability of the roller friction surface deteriorates. More specifically, as shown in FIG. 4, the output shaft 13 is bent, so that the axial end of the second roller 32 on the contact surface with the first roller 31 is deformed toward the first roller 31. As a result, the radial pressing force between the rollers concentrates on a part of the roller contact surface, so that the roller friction surface is worn severely.

  Here, in general, the bearing is in a state in which the inner race and the outer race are in point contact (or line contact) with the rolling elements, and therefore, the support rigidity against the bending of the rotating shaft is lower than that of the support component such as the bush. . Further, in the driving force distribution device 1 of the first embodiment, in order to make the transmission torque capacity between the rollers variable, the output shaft 13 is supported on the crankshafts 51L and 51R by bearings 52L and 52R, and further the crankshafts 51L and 51R. Are supported on bearing supports 23 and 25 by bearings 53L and 53R. That is, since the output shaft 13 is supported by the bearing supports 23 and 25 via the radial double bearings, the deflection of the output shaft 13 becomes remarkable.

[Roller contact surface deformation suppression action]
On the other hand, in the driving force distribution device 1 according to the first embodiment, the axial length W1 of the bearings 52L and 52R is set longer than the axial length W2 of the bearings 53L and 53R. The rigidity can be increased, and the deflection of the output shaft 13 can be suppressed as shown by the two-dot chain line in FIG. Here, the reason why the axial length W2 of the bearings 53L and 53R is shorter than the axial length W1 of the bearings 52L and 52R is that the bearing supports 23 and 25 that support the bearings 53L and 53R are restricted. It is. The reason will be described below.

  In order to increase the axial length W2 of the bearings 53L and 53R, it is necessary to increase the axial length of the bearing supports 23 and 25. However, the bearing supports 23 and 25 are members that receive the reaction force of both rollers, and are made of a material having higher strength and higher specific gravity than the housing 11 and both rollers 31 and 32. Increasing the size of 25 is not preferable from the viewpoint of weight reduction and economy.

  On the other hand, the bearings 52L and 52R are inserted between the output shaft 13 and the center holes 51La and 51Ra of the crankshafts 51L and 51R. Here, since the output shaft 13 is a long rod-like member, even if the axial length W2 of the bearings 52L, 52R is increased, no shape change is required, and no increase in weight or cost is caused. . That is, by making the axial length W1 of the bearings 52L and 52R longer than the axial length W2 of the bearings 53L and 53R, it is possible to suppress the deflection of the output shaft 13 while suppressing an increase in weight and cost.

  In addition, since the amount of deformation of the axial end of the second roller 32 on the roller contact surface with the first roller 31 toward the first roller 31 is suppressed, the contact surface pressure between the rollers can be increased, and torque can be increased. Transmission efficiency is improved.

  Further, since the bending of the output shaft 13 is suppressed, the falling of the ring gears 51Lc and 51Rc provided at the adjacent ends of the crankshafts 51L and 51R is suppressed, so that the second roller 32 and the crankshafts 51L and 51R Therefore, the input to the thrust bearings 54L and 54R interposed between the two is reduced, and the friction can be reduced.

  In the driving force distribution device 1 according to the first embodiment, the bearing support span S1 of the bearings 52L and 52R is set shorter than the bearing support span S2 of the bearings 53L and 53R. The amount of deflection of the output shaft 13 is determined by the maximum amplitude of radial vibration of the output shaft 13, and this maximum amplitude decreases as the bearing support span S1 of the bearings 52L and 52R is shortened. That is, the maximum deflection amount of the output shaft 13 can be reduced, and the deflection can be effectively suppressed.

Next, the effect will be described.
The driving force distribution device 1 according to the first embodiment has the following effects.
(1) Offset with respect to the first roller 31 and the second roller 32, bearing supports 23 and 25 that receive a reaction force generated by the radial pressing contact between the rollers, and the output shaft 13 that is the rotation shaft of the second roller 32 Crankshafts 51L, 51R having a rotating shaft, a pair of bearings 52L, 52R for supporting the output shaft 13 on the crankshafts 51L, 51R, and eccentric outer peripheral portions 51Lb, 51Rb which are rotating shafts of the crankshafts 51L, 51R A pair of bearings 53L and 53R supported on the supports 23 and 25, and an inter-roller pressing force control motor 45 that rotates the crankshafts 51L and 51R to change the radial pressing contact state between the rollers. The axial length W1 was set longer than the axial length W2 of the bearings 53L and 53R.
Thereby, the deformation of the contact surface of the second roller 32 with the first roller 31 can be suppressed to be small, and the durability of the roller friction surface can be prevented from being lowered. Further, the contact surface pressure between the rollers is increased, and the crankshafts 51L and 51R can be prevented from falling, so that the torque transmission efficiency can be improved.
Further, since the axial length W2 of the bearings 53L and 53R can be shortened, the bearing supports 23 and 25 to which the bearings 53L and 53R are attached can be prevented from being enlarged, and an increase in weight and cost can be suppressed.

  (2) Since the bearing support span S1 of the bearings 52L and 52R is set shorter than the bearing support span S2 of the bearings 53L and 53R, the maximum deflection amount of the output shaft 13 can be reduced, and the deflection can be effectively suppressed.

  (3) As a driving force distribution device that determines the torque distribution between the front and rear wheels by distributing a part of the torque to the left and right rear wheels 6L, 6R to the left and right front wheels 9L, 9R, the driving force Using the distribution device 1, the first roller 31 is connected to the input member 12 that forms the torque transmission path to the left and right rear wheels 6L, 6R, and the second roller 32 is the output shaft that forms the torque transmission path to the left and right front wheels 9L, 9R. Concatenated with 13. Accordingly, it is possible to improve the torque transmission efficiency to the left and right rear wheels 9L and 9R during four-wheel drive traveling while suppressing an increase in weight due to the increase in the diameter of the output shaft 13.

FIG. 5 is an enlarged view of a main part of the driving force distribution device 1 according to the second embodiment. In addition, about the site | part which is common in Example 1, it represents with the same name and the same code | symbol.
In the driving force distribution device 1 of Example 2, as shown in FIG. 5, the bearing support span S1 of the bearings 52L and 52R is set to the same length as the bearing support span S2 of the bearings 53L and 53R.
Since the driving force distribution device 1 according to the second embodiment has the above configuration, the output shaft 13 can be prevented from being bent. Therefore, the same effects as the effects (1) and (3) of the first embodiment are obtained.

6L, 6R Left and right rear wheels (main drive wheels)
9L, 9R Left and right front wheels (sub driven wheels)
23,25 Bearing support (rotating support plate)
31 1st roller
32 Second roller
45 (Transmission torque capacity changing means)
51L, 51R Crankshaft (eccentric member)
52L, 52R bearing (inner bearing)
53L, 53R bearing (outer bearing)

Claims (3)

A first roller and a second roller;
A rotating support plate that receives a reaction force generated by a radial pressing contact between the rollers;
An eccentric member having a rotation axis offset with respect to the rotation axis of the second roller;
A pair of inner bearings for supporting the rotating shaft of the second roller on the eccentric member;
A pair of outer bearings for supporting the rotation shaft of the eccentric member on the rotation support plate;
A transmission torque capacity changing means for rotating the eccentric member to change the radial pressing contact state between the rollers;
With
The friction transmission device according to claim 1, wherein an axial length of the inner bearing is set longer than an axial length of the outer bearing. The friction transmission device according to claim 1,
The friction transmission apparatus characterized in that an axial center distance between the pair of inner bearings is set shorter than an axial center distance between the pair of outer bearings. The driving force distribution device according to claim 1 or 2, wherein a part of the torque to the main drive wheels is distributed to the slave drive wheels and output to determine the torque distribution between the main and slave drive wheels. Apply friction transmission device,
Connecting the first roller to a rotating member forming a torque transmission path to the main drive wheel;
A driving force distribution device, wherein the second roller is connected to a rotating member that forms a torque transmission path to the driven wheel.

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