JP6819248B2 - Driving force transmission device - Google Patents

Description

The present invention relates to a driving force transmission device.

Conventionally, a clutch composed of an outer rotating member, an inner rotating member that can rotate relative to the outer rotating member, an outer clutch plate that spline fits the outer rotating member, and an inner clutch plate that spline fits the inner rotating member. A driving force transmission device for a vehicle provided with a cam mechanism for pressing the clutch is mounted on, for example, a four-wheel drive vehicle. Regarding this type of driving force transmission device, the applicant has proposed the driving force transmission device of Patent Document 1.

The driving force transmission device described in Patent Document 1 has an outer clutch plate as a plurality of outer friction plates and an inner clutch plate as a plurality of inner friction plates between a housing as an outer rotating member and an inner shaft as an inner rotating member. A main clutch is arranged in which clutch plates are arranged alternately. The cam mechanism has a pilot cam and a main cam, and a pilot clutch is arranged between the pilot cam and the housing. The pilot cam receives the rotational force of the housing via the pilot clutch and rotates with respect to the main cam, so that the main cam moves in the axial direction and presses the main clutch. As a result, the outer clutch plate and the inner clutch plate are frictionally engaged with each other, and a driving force (torque) is transmitted between the housing and the inner shaft.

Spline teeth are formed on the inner peripheral surface of the housing to which the protrusions of the outer clutch plate engage. Further, spline teeth are formed on the outer peripheral surface of the inner shaft to engage the inner clutch plate and the protrusions of the main cam. A circumferential gap is formed between these protrusions and the spline teeth. Then, due to this gap, the outer clutch plate moves smoothly with respect to the housing, and the inner clutch plate and the main cam move smoothly with respect to the inner shaft in the axial direction.

In order to achieve the above object, the present invention extends inward from a cylindrical portion having a plurality of first spline teeth extending in the direction of rotation on the inner peripheral surface and one end portion in the axial direction of the cylindrical portion. A bottomed cylindrical outer rotating member integrally having an existing bottom portion, and a plurality of bottomed cylindrical outer rotating members that are supported on the outer peripheral surface so as to be relatively rotatable on the inner side of the cylindrical portion in the same direction as the outer rotating member and extend in the direction of the rotation axis. An inner rotating member on which a second spline tooth is formed, a plurality of first friction plates having a first protrusion engaging with the plurality of first spline teeth formed on an outer peripheral portion thereof, and the plurality of first friction plates. A plurality of second friction plates alternately arranged with one friction plate and having a second protrusion engaged with the plurality of second spline teeth formed on the inner peripheral portion, and the plurality of first friction plates. The bottom portion of the outermost rotating member among the plurality of first friction plates and the plurality of second friction plates is provided with a pressing mechanism for pressing the plate and the plurality of second friction plates toward the bottom side. the bottom side of the one friction plate disposed on the side, rotational resistance reducing means for reducing the rotational resistance against the bottom of the one friction plate disposed et al is, the rotational resistance reducing means, a plurality of rolling elements And a rolling bearing provided with a cage for holding the plurality of rolling elements, or a driving force transmission device which is a resin member arranged between the one friction plate and the bottom portion .

Japanese Unexamined Patent Publication No. 2012-72892

According to the driving force transmission device configured as described above, abnormal noise generated when a reverse state occurs in the differential rotation between the housing which is the outer rotating member and the inner shaft which is the inner rotating member is greatly suppressed. However, even if such measures are taken, a slight abnormal noise may still be generated when the reverse rotation state of the differential rotation occurs. The present inventors have diligently studied the cause and countermeasures for the generation of this slight abnormal noise, and have come to the present invention.

That is, an object of the present invention is a drive capable of more reliably suppressing an abnormal noise generated when an inverted state occurs in the differential rotation between the outer rotating member and the inner rotating member arranged so as to be relatively rotatable. The purpose is to provide a force transmission device.

In order to achieve the above object, the present invention extends inward from a cylindrical portion having a plurality of first spline teeth extending in the direction of rotation on the inner peripheral surface and one end portion in the axial direction of the cylindrical portion. A bottomed cylindrical outer rotating member integrally having an existing bottom portion, and a plurality of bottomed cylindrical outer rotating members that are supported on the outer peripheral surface so as to be relatively rotatable on the inner side of the cylindrical portion on the same axis as the outer rotating member and extend in the direction of the rotation axis. An inner rotating member on which a second spline tooth is formed, a plurality of first friction plates on which a first protrusion engaging with the plurality of first spline teeth is formed on an outer peripheral portion, and the plurality of first friction plates. A plurality of second friction plates alternately arranged with one friction plate and having a second protrusion engaged with the plurality of second spline teeth formed on the inner peripheral portion, and the plurality of first friction plates. The bottom portion of the outermost rotating member among the plurality of first friction plates and the plurality of second friction plates is provided with a pressing mechanism for pressing the plate and the plurality of second friction plates toward the bottom side. Provided is a driving force transmission device provided with a rotation resistance reducing means for reducing the rotation resistance of the one friction plate with respect to the bottom portion on the bottom side of the friction plate arranged on the side.

According to the driving force transmission device according to the present invention, abnormal noise generated when an inverted state occurs in the differential rotation between the outer rotating member and the inner rotating member arranged so as to be relatively rotatable can be suppressed more reliably. Is possible.

It is a schematic diagram which shows the structure of the four-wheel drive vehicle which mounted the driving force transmission device which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the whole of the driving force transmission device. It is a partially enlarged view of FIG. It is a top view which shows the appearance of a clutch plate, (a) shows the appearance of an inner clutch plate, and (b) shows the appearance of an outer clutch plate. It is explanatory drawing which shows the engaging part with the inner shaft and the front housing in the inner peripheral part and the outer peripheral part of a main clutch by the cross section orthogonal to the rotation axis, and (a) is the engaging part between an inner shaft and a main cam, (a). b) shows the engaging portion between the inner shaft 3 and the inner clutch plate, and (c) shows the engaging portion between the front housing and the outer clutch plate. It is explanatory drawing which schematically explains the movement of each member when a reversal state occurs in the differential rotation of an inner shaft and a front housing, (a) is a steady state, (b) is a reversal initial state. (C) shows a state in which the inversion is further advanced from the inversion initial state. It is a graph which shows the relationship between the rotation angle of the front housing, and the transmission torque when the front housing is reciprocally rotated. In the comparative example, it is a graph which shows the relationship between the rotation angle of the front housing and the transmission torque when the front housing is reciprocally rotated. It is a partially enlarged view which shows the cross section of the driving force transmission device which concerns on 2nd Embodiment of this invention. It is a top view which shows the bottom part of the driving force transmission device which concerns on 3rd Embodiment of this invention. It is a top view which shows the bottom part of the driving force transmission device which concerns on one modification of this invention. It is a partially enlarged view which shows the cross section of the driving force transmission device which concerns on 4th Embodiment of this invention.

Embodiments of the present invention will be described with reference to FIGS. 1 to 12. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect.

[First Embodiment]
FIG. 1 is a schematic view showing a configuration of a four-wheel drive vehicle equipped with a driving force transmission device according to the first embodiment of the present invention. As shown in FIG. 1, the four-wheel drive vehicle 101 includes a driving force transmission device 1, an engine 102 as a driving source, a transaxle 103, front wheels 104 and 104 as a pair of main driving wheels, and a pair of auxiliary driving wheels. It is equipped with rear wheels 105 and 105.

The driving force transmission device 1 is arranged in a driving force transmission path from the front wheel side to the rear wheel side of the four-wheel drive vehicle 101, and is supported on the vehicle body (not shown) of the four-wheel drive vehicle 101 via a differential carrier 106. Has been done.

The driving force transmission device 1 is configured to connect the propeller shaft 107 and the drive pinion shaft 108 so as to be able to transmit torque, and to transmit the driving force of the engine 102 to the rear wheels 105 and 105 in this connected state. There is. The details of the driving force transmission device 1 will be described later.

The engine 102 drives the pair of front wheels 104 and 104 by outputting the driving force to the pair of left and right front axle shafts 109 via the transaxle 103. The transaxle 103 includes an automatic transmission and distributes the output of the automatic transmission to the propeller shaft 107 and the pair of front axle shafts 109.

Further, the engine 102 outputs the driving force to the propeller shaft 107, the driving force transmission device 1, the drive pinion shaft 108, the rear differential 110 and the rear axle shaft 111 via the transaxle 103, so that the pair of rear wheels 105, Drive 105.

(Overall configuration of driving force transmission device 1)
FIG. 2 is a cross-sectional view showing the entire driving force transmission device 1. FIG. 3 is a partially enlarged view of FIG. 4 (a) and 4 (b) are plan views showing the appearance of the inner clutch plate 40 and the outer clutch plate 41 of the driving force transmission device 1.

As shown in FIG. 2, the driving force transmission device 1 includes a housing 2 as an outer rotating member that can rotate relative to the differential carrier 106 (shown in FIG. 1) and an inner rotating member that can rotate relative to the housing 2. The inner shaft 3 is interposed between the inner shaft 3 and the housing 2, the pressing mechanism 10 that converts the rotational force of the housing 2 into the pressing force of the main clutch 4, the main clutch 4 and the housing. It is provided with a rolling bearing 20 as a means for reducing rotational resistance, which is arranged between the two. The pressing mechanism 10 includes a pilot clutch 5 that is parallel to the main clutch 4 along an axial direction parallel to the rotation axis O of the housing 2 and the inner shaft 3, an actuator 6 that generates a pressing force of the pilot clutch 5, and an actuator 6. It is provided with a cam mechanism 7 that receives the rotational force of the housing 2 via the pilot clutch 5 by the operation of.

(Structure of housing 2)
As shown in FIG. 2, the housing 2 includes a bottomed cylindrical front housing 8 and a rear housing 9 coupled to the front housing 8 so as to rotate integrally with the front housing 8 by screwing or the like, and the differential carrier 106 (FIG. 1). Rotatably housed in (shown in) with the rotation axis O as the central axis. An annular accommodation space 2a is formed between the housing 2 and the inner shaft 3. Lubricating oil is sealed in this accommodation space 2a.

The front housing 8 has a hollow cylindrical portion 8b and a disk-shaped bottom portion 8a extending inward from one end of the cylindrical portion 8b in the axial direction and partially projecting in the axial direction of the cylindrical portion 8b. It is integrally held and connected to the engine 102 (shown in FIG. 1) via a transaxle 103 (shown in FIG. 1) and a propeller shaft 107 (shown in FIG. 1). A plurality of first spline teeth 80b (hereinafter, simply referred to as "spline teeth 80b") extending in the rotation axis direction are formed on the inner peripheral surface of the cylindrical portion 8b. The front housing 8 is configured to receive the driving force of the engine 102 from the propeller shaft 107 and rotate around the rotation axis O together with the rear housing 9.

The rear housing 9 is formed by integrally connecting the first to third housing elements 91 to 93 by welding or the like, and is screwed to the inner peripheral surface of the opening of the front housing 8. The rear housing 9 is provided with an annular accommodation space 9a that opens in the same direction as the opening direction of the front housing 8.

The first housing element 91 is arranged on the inner peripheral side of the rear housing 9, and is formed of a cylindrical member made of a magnetic material. The second housing element 92 is arranged on the outer peripheral side of the rear housing 9, and is formed of a cylindrical member made of a magnetic material like the first housing element 91. The third housing element 93 is interposed between the first housing element 91, the second housing element, and 92, and is formed of an annular member for connecting the housing element, which is made of a non-magnetic material such as stainless steel. ..

A yoke 94 that supports the electromagnetic coil 6a, which will be described later, is arranged between the first housing element 91 and the third housing element 93. The yoke 94 is detented with respect to the differential carrier 106. A bearing 95 is arranged between the yoke 94 and the third housing element 93.

(Structure of inner shaft 3)
The inner shaft 3 has two large and small cylindrical portions 3a and 3b having different outer diameters, and a stepped portion 3c interposed between the two cylindrical portions 3a and 3b. Further, the inner shaft 3 is arranged inside the housing 2 on the rotation axis O of the housing 2, that is, coaxially with the housing 2, and is supported by the housing 2 via bearings 17 and 18 so as to be relatively rotatable. It is formed by a cylindrical member.

A plurality of second spline teeth 30a (hereinafter, simply referred to as "spline teeth 30a") exposed in the accommodation space 2a and extending in the rotation axis direction are formed on the outer peripheral surface of the large-diameter cylindrical portion 3a. There is.

A storage space 3d for accommodating the tip of the drive pinion shaft 108 (shown in FIG. 1) is formed on the inner peripheral surface of the small-diameter cylindrical portion 3b, and the outer peripheral surface of the drive pinion shaft 108 is formed on the inner peripheral surface of the accommodation space 3d. A spline fitting portion 30b for spline fitting is provided on the surface.

(Structure of main clutch 4)
The main clutch 4 is a wet multi-plate clutch having a plurality of outer clutch plates 41 as a plurality of first friction plates and a plurality of inner clutch plates 40 as a plurality of second friction plates. The main clutch 4 is accommodated in the accommodation space 2a and is arranged between the cylindrical portion 8b of the front housing 8 and the cylindrical portion 3a of the inner shaft 3. Then, the main clutch 4 can frictionally engage the clutch plates of the inner clutch plate 40 and the outer clutch plate 41 that are adjacent to each other, and release the frictional engagement to transmit torque between the housing 2 and the inner shaft 3. It is configured to connect to.

The inner clutch plate 40 and the outer clutch plate 41 are formed in an annular shape, and their side surfaces are opposed to each other and are alternately arranged on the rotation axis O. Further, the inner clutch plate 40 can move axially with respect to the inner shaft 3 and the outer clutch plate 41 can move axially with respect to the front housing 8 along the rotation axis O.

As shown in FIGS. 2 and 4A, a plurality of protrusions 41a as first protrusions projecting outward in the radial direction are formed on the outer peripheral portion of the outer clutch plate 41 along the circumferential direction. ing. Further, in the outer clutch plate 41, a region facing the friction surface 401a of the friction material 401 of the inner clutch plate 40, which will be described later, is formed as the friction surface 411a.

The outer clutch plate 41 is arranged so as to be integrally rotatable with the front housing 8 and movable along the direction of the rotation axis O by engaging the protrusions 41a with the plurality of spline teeth 80b of the front housing 8.

As shown in FIGS. 2 and 4B, a plurality of protrusions 40a as second protrusions protruding inward in the radial direction are formed on the inner peripheral portion of the inner clutch plate 40 along the circumferential direction. Has been done. Further, on the inner clutch plate 40, an annular friction material 401 is attached to the outer peripheral portion of the side surface thereof. Further, a plurality of oil holes 40b for flowing lubricating oil are formed on the inner peripheral side of the friction material 401. The surface of the friction material 401 is configured as a friction surface 401a that slides on the outer clutch plate 41.

The inner clutch plate 40 is arranged so as to be integrally rotatable with the inner shaft 3 and movable along the direction of the rotation axis O by engaging the plurality of protrusions 40a with the plurality of spline teeth 30a of the inner shaft 3. ..

(Configuration of pilot clutch 5)
As shown in FIG. 2, the pilot clutch 5 has a plurality of inner clutch plates 50 as a third friction plate that can be frictionally engaged with each other by moving the armature 6b toward the electromagnetic coil 6a by driving the actuator 6 (described later). It also has a plurality of outer clutch plates 51 as a fourth friction plate. The pilot clutch 5 is arranged between the armature 6b and the rear housing 9 in the axial direction in the accommodation space 2a.

The inner clutch plate 50 and the outer clutch plate 51 are formed in an annular shape, and their side surfaces are opposed to each other and are alternately arranged on the rotation axis O. The inner clutch plate 50 has a plurality of protrusions 50a on the inner peripheral portion thereof, and the protrusions 50a are engaged with the spline teeth 71a of the pilot cam 71 described later to regulate the relative rotation with the pilot cam 7b. They are connected so that they can move in the axial direction.

The outer clutch plate 51 has a plurality of protrusions 51a on the outer peripheral portion thereof, and the protrusions 51a are engaged with the spline teeth 80b to regulate the rotation with respect to the front housing 8 and are connected so as to be movable in the axial direction. ..

(Structure of actuator 6)
The actuator 6 has an electromagnetic coil 6a and an armature 6b, and is arranged on the rotation axis O of the housing 2. Then, the actuator 6 is configured to press and frictionally engage the outer clutch plate 51 and the inner clutch plate 50 of the pilot clutch 5 by moving the armature 6b to the electromagnetic coil 6a side due to the generation of the electromagnetic force of the electromagnetic coil 6a. Has been done.

The electromagnetic coil 6a is housed in the housing space 9a of the rear housing 9 and is attached to the yoke 94. Then, as shown by the broken line in FIG. 2, the electromagnetic coil 6a forms a magnetic circuit G straddling the yoke 94, the pilot clutch 5, the armature 6b, the rear housing 9, and the like by energization, and the armature 6b is on the rear housing 9 side. It is configured to generate an electromagnetic force to impart a moving force to. The outer clutch plate 51 and the inner clutch plate 50 are pressed against each other by this moving force to generate a frictional force.

The armature 6b has a straight spline fitting portion 60b along the rotation axis O on its outer peripheral portion, and the straight spline fitting portion 60b is fitted to the spline teeth 80b so that it cannot rotate relative to the front housing 8 and is axial. It is movably connected.

A coil current is supplied to the electromagnetic coil 6a from a control device (not shown). The density of the magnetic flux generated in the magnetic circuit G changes depending on the magnitude of the coil current, and the larger the coil current, the stronger the pressing force that the armature 6b presses on the pilot clutch 5.

(Structure of cam mechanism 7)
As shown in FIG. 2, the cam mechanism 7 is an annular main cam 70 as a pressing member that rotates by receiving a rotational force from the inner shaft 3, is arranged to face the main cam 70, and rotates with respect to the main cam 70. As a result, the main cam 70 has an annular pilot cam 71 as a thrust applying member that applies thrust to the bottom portion 8a side of the front housing 8, and a spherical cam follower 72 interposed between the main cam 70 and the pilot cam 71. It is arranged between the main clutch 4 and the rear housing 9 in the axial direction in the accommodation space 2a. The main cam 70 is urged toward the pilot cam 71 by a return spring 73 formed of a disc spring arranged between the main cam 70 and the step portion 3c. Then, the cam mechanism 7 receives the rotational force from the housing 2 by the clutch operation of the pilot clutch 5, and converts the rotational force in which the pilot cam rotates relative to the main cam 70 into a pressing force that becomes the clutch force of the main clutch 4. It is configured as follows.

The main cam 70 has a clutch plate pressing portion 70a that presses and frictionally engages the inner clutch plate 40 and the outer clutch plate 41, and receives the cam thrust generated by the relative rotation with the pilot cam 71 from the cam follower 72 in the axial direction. Move to. The pressing portion 70a of the main cam 70 is arranged at a position where the plurality of outer clutch plates 41 and the plurality of inner clutch plates 40 are sandwiched between the pressing portion 70a and the bottom portion 8a of the front housing 8.

Further, the main cam 70 is provided with a plurality of protrusions 70b that engage with the spline teeth 30a of the inner shaft 3 on the inner peripheral side of the clutch plate pressing portion 70a. By engaging the protrusion 70b with the spline teeth 30a, the rotation of the main cam 70 with respect to the inner shaft 3 is restricted.

The pilot cam 71 has a bearing 19 interposed between the pilot cam 71 and the first housing element 91 of the rear housing 9, and is arranged so as to be rotatable relative to the inner shaft 3. A plurality of third spline teeth 71a (hereinafter, simply "spline teeth") extend on the outer peripheral surface of the pilot cam 71 and are fitted to the protrusions 50a of the inner clutch plate 50 so as to be relatively non-rotatable and axially movable. 71a ”) is formed.

A plurality of (for example, six) cam grooves 70c and 71b extending in the circumferential direction are formed on the facing surfaces of the main cam 70 and the pilot cam 71, respectively. The cam grooves 70c and 71b are formed so as to have the deepest axial depth at the central portion in the circumferential direction and shallower toward the end portion. The cam follower 72 is arranged between the cam grooves 70c and 71b, respectively, and rolls from the central portion (neutral position) of the cam grooves 70c and 71b in the circumferential direction to one side or the other side in the circumferential direction to form a main cam 70. The pilot cam 71 is separated from the pilot cam 71 to generate a pressing force that is a clutch force of the main clutch 4. The pressing mechanism 10 presses the plurality of inner clutch plates 40 and the plurality of outer clutch plates 41 toward the bottom 8a side of the front housing 8 by the operation of the cam mechanism 7.

(Structure of rolling bearing 20)
As shown in FIGS. 2 and 3, the rolling bearing 20 has a bottom 8a rather than one friction plate arranged on the bottom 8a side of the front housing 8 most of the plurality of inner clutch plates 40 and the plurality of outer clutch plates 41. It is provided on the side. In the present embodiment, this "one friction plate" is the outer clutch plate 41, but the main clutch 4 may be configured so that the "one friction plate" is the inner clutch plate 40. In the following description, when it is necessary to distinguish the outer clutch plate 41 arranged on the bottom 8a side of the plurality of outer clutch plates 41 from the other outer clutch plates 41, the outer clutch plate 41 is used for convenience of explanation. The clutch plate 41 is referred to as an outer clutch plate 41A by changing its code.

The rolling bearing 20 includes a first raceway ring 21 facing the outer clutch plate 41A, a second raceway ring 22 facing the bottom 8a of the front housing 8, a first raceway wheel 21 and a second raceway ring 22. A cage 23 arranged between the cages 23 and a plurality of columnar rollers 24 as rolling elements rotatably held in the holding holes 23a formed in the cage 23 are provided.

The rolling bearing 1 facilitates rotation of the outer clutch plate 41A with respect to the bottom portion 8a by rolling the plurality of rollers 24 held by the cage 23, that is, reduces rotational resistance.

FIG. 5 is an explanatory view showing the engaging portions of the inner shaft 3 and the front housing 8 at the inner peripheral portion of the main cam 70 and the inner peripheral portion and the outer peripheral portion of the main clutch 4 in a cross section orthogonal to the rotation axis O. a) is an engaging portion between the inner shaft and the main cam, (b) is an engaging portion between the inner shaft 3 and the inner clutch plate 40, and (c) is an engaging portion between the front housing 8 and the outer clutch plate 41. Are shown respectively.

(The engaging portion between the inner shaft 3 and the main cam 70)
As shown in FIG. 5A, there is a circumferential gap (play) between the spline teeth 30a of the inner shaft 3 and the protrusion 70b of the main cam 70, and the inner shaft 3 and the inner shaft 3 have an angle range corresponding to this gap. The main cam 70 and the main cam 70 can rotate relative to each other. In FIG. 5A, the main cam 70 at the first position where the main cam 70 is rotated in the first direction (counterclockwise) with respect to the inner shaft 3 until the protrusion 70b abuts on the spline teeth 30a is shown by a solid line. Similarly, the main cam 70 at the second position rotated in the second direction (clockwise) until the protrusion 70b of the main cam 70 abuts on the spline teeth 30a of the inner shaft 3 is shown by a two-point chain line.

Further, in FIG. 5A, the central axis of the protrusion 70b of the main cam 70 shown by the solid line and the alternate long and short dash line is shown by the alternate long and short dash line. The angle (gap angle) θ ₃ formed by the central axis of each of the protrusions 70b at the first and second positions corresponds to the size of the circumferential gap between the spline teeth 30a of the inner shaft 3 and the protrusion 70b of the main cam 70. it is an angle that, the inner shaft 3 and the main cam 70 is relatively rotatable range of the angle theta _3. In this embodiment, the angle θ ₃ is set to 0.53 °.

(The engaging portion between the inner shaft 3 and the inner clutch plate 40)
As shown in FIG. 5B, there is a circumferential gap (play) between the spline teeth 30a of the inner shaft 3 and the protrusion 40a of the inner clutch plate 40, and the inner shaft has an angle range corresponding to this gap. 3 and the inner clutch plate 40 can rotate relative to each other. In FIG. 5B, the inner clutch plate 40 when the inner clutch plate 40 is rotated in the first direction (counterclockwise) with respect to the inner shaft 3 until the protrusion 40a abuts on the spline teeth 30a is shown by a solid line. Similarly, the inner clutch plate 40 when the protrusion 40a of the inner clutch plate 40 is rotated in the second direction (clockwise) until it comes into contact with the spline teeth 30a of the inner shaft 3 is shown by a two-point chain line. ..

Further, in FIG. 5B, the central axis of the protrusion 40a of the inner clutch plate 40 shown by the solid line and the alternate long and short dash line is shown by the alternate long and short dash line. The angle (gap angle) θ ₂ formed by the central axis of each of the protrusions 40a at the first and second positions is the size of the circumferential gap between the spline teeth 30a of the inner shaft 3 and the protrusion 40a of the inner clutch plate 40. The inner shaft 3 and the inner clutch plate 40 can rotate relative to each other within the range of this angle θ ₂ . In this embodiment, the angle θ ₂ is set to 0.56 °.

(The engaging portion between the front housing 8 and the outer clutch plate 41)
As shown in FIG. 5 (c), there is a circumferential gap (play) between the spline teeth 80b of the front housing 8 and the protrusion 41a of the outer clutch plate 41, and the front housing has an angle range corresponding to this gap. 8 and the outer clutch plate 41 can rotate relative to each other. In FIG. 4C, the outer clutch plate 41 at the first position where the outer clutch plate 41 is rotated in the first direction (counterclockwise) with respect to the front housing 8 until the protrusion 41a abuts on the spline teeth 80b. The outer clutch plate 41 at the second position rotated in the second direction (clockwise) until the protrusion 41a of the outer clutch plate 41 abuts on the spline teeth 80b of the front housing 8 with a two-point chain wire. Each is shown.

Further, in FIG. 5C, the central axis of the protrusion 41a of the outer clutch plate 41 shown by the solid line and the alternate long and short dash line is shown by the alternate long and short dash line. The angle (gap angle) θ ₁ formed by the central axes of the respective protrusions 41a at the first and second positions is the size of the circumferential gap between the spline teeth 80b of the front housing 8 and the protrusions 41a of the outer clutch plate 41. The front housing 8 and the outer clutch plate 41 can rotate relative to _each other within the range of this angle θ ₁ . In this embodiment, θ ₁ is set to 2.06 °.

In the present embodiment, θ ₃ and θ ₂ are equivalent (the difference between θ ₃ and θ ₂ is 0.03 ° or less), the angle θ ₁ is larger than the angle θ ₂ , and the angle θ ₁ and the angle. The driving force transmission device 1 is configured so that the sum with θ ₂ (θ ₁ + θ ₂ ) is 1.0 ° or more larger than the angle θ ₃ . That is, the inner shaft 3, the front housing 8, the main cam 70, the inner clutch plate 40, and the outer clutch plate 41 are configured so as to satisfy the relationship of θ ₁ + θ ₂ − θ ₃ ≧ 1.0 °. The above-mentioned values of θ ₁ to θ ₃ are examples, and are not limited to these values and can be adjusted as appropriate.

With this configuration, the rolling bearing 20 is provided between the spline teeth 80b of the pair of front housings 8 adjacent to each other in the circumferential direction of the cylindrical portion 8b of the front housing 8 and the protrusion 41a of the outer clutch plate 41. The rotational resistance between the outer clutch plate 41A and the bottom portion 8a of the front housing 8 is suppressed in an angle range corresponding to a predetermined gap.

(Actions and effects of the first embodiment)
FIG. 6 is an explanatory diagram schematically explaining the movement of each member when an inverted state occurs in the differential rotation of the inner shaft 3 and the front housing 8. In FIG. 6, arrows A and B, which will be described later, are shown focusing on the relative relationship between the inner shaft 3 and the front housing 8.

FIG. 6A shows a torque transmission state in which torque in the direction in which the inner shaft 3 rotates in the direction of arrow A acts on the front housing 8. The clutch plate pressing portion 70a of the main cam 70 applies pressing pressure to the main clutch 4 by the clutch operation of the pilot clutch 5, and the inner clutch plate 40 and the outer clutch plate 41 are frictionally engaged with each other.

In this state, the spline teeth 80b of the front housing 8 abut on the protrusion 41a of the outer clutch plate 41 in the direction opposite to the arrow A, and the protrusion 40a of the inner clutch plate 40 opposes the spline teeth 30a of the inner shaft 3 in the direction opposite to the arrow A. Torque is transmitted between the front housing 8 and the inner shaft 3 via the main clutch 4 in contact with the direction of.

In FIG. 6B, the rotation direction of the inner shaft 3 with respect to the front housing 8 is reversed from the state shown in FIG. 6A, and the inner shaft 3 is in the direction of arrow B (opposite direction of arrow A) with respect to the front housing 8. Shows the initial state of inversion when torque in the direction of rotation is applied to.

When the differential rotation state between the inner shaft 3 and the front housing 8 is reversed, as shown in FIG. 6B, the spline teeth 30a of the inner shaft 3 hit the protrusion 40a of the inner clutch plate 40 in the direction of arrow B. Get in touch.

FIG. 6 (c) shows a state in which the reversal progresses further from the initial reversal state shown in FIG. 6 (b), and the protrusion 41a of the outer clutch plate 41 abuts on the spline teeth 80b of the front housing 8 in the direction of arrow B.

Here, if the rolling bearing 20 does not exist and the outer clutch plate 41A is pressed toward the bottom 8a side of the housing 8 by the thrust of the cam mechanism 7 until the state shown in FIG. 6C is reached, the outer clutch plate An abnormal noise (collision noise) may be generated due to a large impact when the protrusion 41a of the 41 abuts on the spline teeth 80b of the front housing 8 in the direction of the arrow B. In the present embodiment, as described above, the gap angles θ ₁ , θ ₂ , and θ ₃ of each spline are configured to satisfy the inequality of θ ₁ + θ ₂ − θ ₃ ≧ 1.0 °, thereby causing this abnormal noise. Is suppressed. That is, by constituting the main clutch 4 and a cam mechanism 7 so as to satisfy the inequality, with the thrust of the cam mechanism 7 is not generated, as shown in dashed lines A ₁ and A ₂ in FIG. 6 (c), the outer The protrusion 41a of the clutch plate 41 can be brought into contact with the spline teeth 80b of the front housing 8 in the direction of arrow B, and the impact at the time of this contact is alleviated.

However, when the rolling bearing 20 does not exist, even if the above measures are taken, a slight abnormal noise may be generated when the reverse rotation state of the differential rotation occurs. In this abnormal noise, the frictional force generated between the outer clutch plate 41A and the bottom portion 8a of the housing 8 fluctuates greatly from the state shown in FIG. 6A to the state shown in FIG. 6C. This is generated in the drive line on the auxiliary drive wheel side from the transaxle 103 to the pair of rear wheels 105 and 105 via the propeller shaft 107 and the rear differential 110.

More specifically, when the differential rotation is reversed, the transmission torque between the front housing 8 and the inner shaft 3 is the static friction force between the outer clutch plate 41A and the bottom 8a of the front housing 8. The outer clutch plate 41A then rotates with respect to the bottom 8a of the front housing 8 and the static friction transitions to dynamic friction, so that the transmission torque drops sharply. As described above, when the transmission torque increases or decreases in a short time, the load (transmitting driving force) of the entire drive line suddenly increases or decreases, and abnormal noise is generated.

In particular, in the present embodiment, if θ ₁ is increased so as to satisfy the above inequality, the time for the outer clutch plate 41A to frictionally slide on the bottom 8a of the front housing 8 becomes longer when the differential rotation is reversed, which is more different. Sound is likely to be generated.

Therefore, in the present embodiment, the outer clutch plate 41A and the bottom 8a of the front housing 8 are formed by arranging the rolling bearing 20 as a means for reducing the rotational resistance on the bottom 8a side of the housing 8 with respect to the outer clutch plate 41A. It is configured to rotate relatively without receiving rotational resistance. With this configuration, when the state shown in FIG. 6A changes to the state shown in FIG. 6B, transmission by static friction force is performed between the outer clutch plate 41A and the bottom portion 8a of the front housing 8. No torque is generated, and therefore there is no variation in the transmitted torque when the static friction state transitions to the dynamic friction state. As a result, the generation of abnormal noise in the drive line due to sudden fluctuations in the transmission torque is suppressed. That is, in the present embodiment, in addition to the measures related to the above-mentioned clearance angle, the front housing 8 and the inner are provided by providing a rotation resistance reducing means between the outer clutch plate 41A and the bottom portion 8a of the housing 8. It is possible to more reliably suppress abnormal noise generated when an inverted state occurs in the differential rotation with the shaft 3.

FIG. 7 shows the front housing when the inner shaft 3 is subjected to rotational resistance by the braking means and the front housing 8 is reciprocally rotated with the original position of the rotation angle (rotation angle = 0 °). It is a graph which shows the relationship between the rotation angle and the torque transmitted to an inner shaft. As a comparative example, FIG. 8 is a graph showing the relationship between the rotation angle of the front housing and the torque transmitted to the inner shaft in a conventional configuration having no rotation resistance reducing means.

In the case of using the conventional driving force transmission device rotational resistance reducing means such as a bearing is not provided between the bottom 8a and the main clutch 4 of the front housing 8, the torque transmitted by the broken line A ₃ in FIG. 8 and whereas the temporary increase as indicated by a _4, in the case of using the driving force transmission device 1 according to this embodiment, as shown in broken line a ₅ and a ₆ of Fig. 7, the conventional The increase in torque as seen in the driving force transmission device does not occur, which suppresses the generation of abnormal noise.

Further, by configuring the clearance angles θ ₁ , θ ₂ , and θ ₃ of each spline so as to satisfy the above inequality, the protrusion 41a of the outer clutch plate 41 contacts the spline teeth 80b of the front housing 8 in the direction of arrow B. the amount of transmitted torque is temporarily increased when the (refer to a broken line B ₁ and B ₂₎ is half suppressed to less if no measures are taken by this arrangement, generation of noise is suppressed.

In the present embodiment, in the configuration in which each clearance angle satisfies the above-mentioned inequality, the rolling bearing 20 is provided between the outer clutch plate 41A and the bottom portion 8a of the housing 8, but each clearance angle satisfies the above-mentioned inequality. Even if the rolling bearing 20 is provided between the outer clutch plate 41A and the bottom portion 8a of the housing 8 in a configuration that does not satisfy the requirements, it is possible to suppress abnormal noise caused by a sudden increase or decrease in the load of the entire drive line.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In this drawing, elements having the same configuration and function as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 9 is a partially enlarged view showing a cross section of the driving force transmission device according to the second embodiment of the present invention. In the present embodiment, a resin washer 200 as a resin member, which is a means for reducing rotational resistance, is arranged between the outer clutch plate 41A and the bottom portion 8a of the housing 2. The resin washer 200 includes PTA (material high-purity terephthalic acid), PBT (polybutylene terephthalate), PET (polyethylene terephthalate), PTT (polytrimethylene terephthalate), PTFE (ethylene tetrafluoride), etc. It is an annular member made of a plastic material. The washer is not limited to the one made of resin, and may be composed of, for example, a lubricant such as molybdenum disulfide or graphite.

Of the surface of the resin washer 200, one surface 200a facing the outer clutch plate 41A has a static friction coefficient between the outer clutch plate 41A and the static friction when the outer clutch plate 41A and the bottom 8a are in direct contact with each other. It has a value smaller than the coefficient (hereinafter, referred to as "conventional static friction coefficient") and smaller than the static friction coefficient between the outer clutch plate 41 and the inner clutch plate 40. Further, the other surface 200b of the resin washer 200, that is, the surface facing the bottom 8a, has a static friction coefficient between the bottom 8a and the other surface 200b, which is smaller than the conventional static friction coefficient.

Even with the driving force transmission device configured as described above, the rotational resistance between the bottom portion 8a of the housing 2 and the surface of the outer clutch plate 41A facing the bottom portion 8a is reduced as compared with the conventional configuration. It is possible to suppress the occurrence of sudden torque fluctuations that cause abnormal noise.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. In this drawing, elements having the same configuration and function as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 10 is a plan view showing the bottom portion of the driving force transmission device according to the third embodiment of the present invention, and is a view seen from the opening side of the front housing 8. As shown in FIG. 10, a plurality of grooves 300 having a predetermined depth are formed on the inner surface 8c of the bottom portion 8a on the opening side of the front housing 8, and each of them is arranged radially. Lubricating oil can be stored in the groove 300. By storing the lubricating oil in the groove 300 formed on the inner surface 8c of the bottom portion 8a, the rotation of the outer clutch plate 41A with respect to the bottom portion 8a becomes smooth, and the groove 300 is formed on the inner surface 8c to form the outer clutch plate 41A. Since the contact area with the inner surface 8c is reduced, the rotational resistance between the bottom portion 8a of the housing 2 and the surface of the outer clutch plate 41A facing the bottom portion 8a is reduced, and sudden torque fluctuations that cause abnormal noise are reduced. Can be suppressed.

(Modification example)
It should be noted that any concave shape is sufficient as long as the lubricating oil can flow, and the shape, size, number and the like can be appropriately adjusted without being limited to the above-mentioned grooves. For example, in the above embodiment, the grooves formed on the inner surface 8c of the bottom 8a of the housing 2 are arranged radially, but as shown in FIG. 11, they may be arranged in a grid pattern (numbering in FIG. 11). See "300b").

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. In this drawing, elements having the same configuration and function as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 12 is a partially enlarged view showing a cross section of the driving force transmission device according to the fourth embodiment of the present invention. As shown in FIG. 12, the resin coating 400 is formed on the inner surface 8c of the bottom 8a of the housing 2 in which at least the friction surface 411a (see FIG. 4A) of the outer clutch plate 41 is formed in the radial direction. Is given. For the resin coating 400, for example, a fluororesin coating can be used. The resin coating 400 is not limited to the fluororesin coating, as long as the static friction coefficient with the outer clutch plate 41A can be made smaller than the static friction coefficient in the uncoated configuration. , Can be selected as appropriate. Further, the side surface of the outer clutch plate 41A may be coated with resin instead of the inner surface 8c of the bottom portion 8a of the housing 2.

By applying a fluororesin coating to the inner surface 8c of the bottom 8a of the housing 2, between the bottom 8a of the housing 2 and the surface of the outer clutch plate 41A facing the bottom 8a, as in the above-described embodiment and modification. It is possible to reduce the rotational resistance of the housing and suppress the occurrence of sudden torque fluctuations that cause abnormal noise.

(Additional note)
Although the present invention has been described above based on the first to fourth embodiments, these embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention. Further, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the first and second embodiments described above, the case where the present invention is applied to the driving force transmission device provided on the drive line on the auxiliary drive wheel side has been described, but the present invention is not limited to this, and the present invention is automatic. It can also be applied to a driving force transmission device that transmits a driving force between rotating members in a transmission.

1 ... Driving force transmission device 2 ... Housing (outer rotating member)
3 ... Inner shaft (inner rotating member)
30a ... Second spline tooth 4 ... Main clutch 6 ... Actuator 8 ... Front housing 8a ... Bottom 8b ... Cylindrical portion 80b ... First spline tooth 20 ... Rolling bearing (rotational resistance reducing means)
23 ... Cage 24 ... Roller (rolling body)
40 ... Inner clutch plate (second friction plate)
40a ... Second protrusions 41, 41A ... Outer clutch plate (first friction plate)
41a ... 1st protrusion 50 ... Inner clutch plate (3rd friction plate)
51 ... Outer clutch plate (fourth friction plate)
7 ... Cam mechanism 70 ... Main cam (pressing member)
71 ... Pilot cam (thrust applying member)
71a ... Third spline tooth 10 ... Pressing mechanism 200 ... Resin washer (resin member)
300 ... Groove 400 ... Resin coating

Claims (5)

The outer side of a bottomed cylindrical shape integrally having a cylindrical portion having a plurality of first spline teeth extending in the rotation axis direction on the inner peripheral surface and a bottom portion extending inward from one axial end portion of the cylindrical portion. With rotating members
An inner rotating member that is supported on the inside of the cylindrical portion coaxially with the outer rotating member so as to be relatively rotatable, and a plurality of second spline teeth extending in the rotation axis direction are formed on the outer peripheral surface.
A plurality of first friction plates having a first protrusion engaged with the plurality of first spline teeth formed on the outer peripheral portion thereof.
A plurality of second friction plates alternately arranged with the plurality of first friction plates and having a second protrusion formed on the inner peripheral portion thereof to engage with the plurality of second spline teeth.
It is provided with a pressing mechanism for pressing the plurality of first friction plates and the plurality of second friction plates toward the bottom side.
The one friction plate is located on the bottom side of the plurality of first friction plates and the one friction plate arranged on the bottom side of the outermost rotating member among the plurality of second friction plates. rotational resistance reducing means for reducing the rotational resistance against the bottom is provided with,
The rolling resistance reducing means is a rolling bearing including a plurality of rolling elements and a cage for holding the plurality of rolling elements.
Driving force transmission device. The pressing mechanism
A pressing member arranged at a position sandwiching the plurality of first friction plates and the plurality of second friction plates with the bottom portion and whose rotation with respect to the inner rotating member is restricted.
A thrust applying member that is arranged to face the pressing member and that applies a thrust to the bottom side of the pressing member by rotating with respect to the pressing member.
A third friction plate whose relative rotation with the thrust applying member is restricted, and
A fourth friction plate, which is arranged to face the third friction plate and whose rotation with respect to the outer rotating member is restricted,
An actuator that presses the third friction plate and the fourth friction plate to frictionally engage them is provided.
The driving force transmission device according to claim 1. The outer side of a bottomed cylindrical shape integrally having a cylindrical portion having a plurality of first spline teeth extending in the rotation axis direction on the inner peripheral surface and a bottom portion extending inward from one axial end portion of the cylindrical portion. With rotating members
An inner rotating member that is supported on the inside of the cylindrical portion coaxially with the outer rotating member so as to be relatively rotatable, and a plurality of second spline teeth extending in the rotation axis direction are formed on the outer peripheral surface.
A plurality of first friction plates having a first protrusion engaged with the plurality of first spline teeth formed on the outer peripheral portion thereof.
A plurality of second friction plates alternately arranged with the plurality of first friction plates and having a second protrusion formed on the inner peripheral portion thereof to engage with the plurality of second spline teeth.
It is provided with a pressing mechanism for pressing the plurality of first friction plates and the plurality of second friction plates toward the bottom side.
The one friction plate is located on the bottom side of the plurality of first friction plates and the one friction plate arranged on the bottom side of the outermost rotating member among the plurality of second friction plates. A rotation resistance reducing means for reducing the rotation resistance with respect to the bottom is provided.
The rotational resistance reducing means is a resin member arranged between the one friction plate and the bottom portion.
Driving force transmission device. The pressing mechanism
A pressing member arranged at a position sandwiching the plurality of first friction plates and the plurality of second friction plates with the bottom portion and whose rotation with respect to the inner rotating member is restricted.
A thrust applying member that is arranged to face the pressing member and that applies a thrust to the bottom side of the pressing member by rotating with respect to the pressing member.
A third friction plate whose relative rotation with the thrust applying member is restricted, and
A fourth friction plate, which is arranged to face the third friction plate and whose rotation with respect to the outer rotating member is restricted,
An actuator that presses the third friction plate and the fourth friction plate to frictionally engage them is provided.
The driving force transmission device according to claim 3. A predetermined gap is provided between the pair of the first spline teeth adjacent to each other in the circumferential direction of the cylindrical portion and the first protrusion.
The rotation resistance reducing means suppresses the rotation resistance in an angle range corresponding to the predetermined gap.
The driving force transmission device according to any one of claims 1 to 4.

Images