Vehicle transfer structure

Abstract

A vehicle transfer structure includes a main-drive-wheel output shaft that receives torque from a drive source and outputs it to main drive wheels, a part-time-drive-wheel output shaft provided parallel to the main-drive-wheel output shaft, a coupling provided on the main-drive-wheel output shaft and which partially extracts the torque to the part-time-drive-wheel output shaft via a transmission mechanism, and a damper disposed on the main-drive-wheel output shaft. The coupling is provided with an input-side coupling part coupled to an inner circumferential part of the damper. The input-side coupling part is coupled, via a spline-fitted section, to an output-side coupling part of a drive force transmission member which is coupled to an outer circumferential part of the damper and transmits a drive force to a driving-side transmission member of the transmission mechanism. The spline-fitted section allows a relative rotation between the input- and output-side coupling parts within a given angle.

Claims

1. A vehicle transfer structure, comprising: a main-drive-wheel output shaft configured to receive torque from a drive source and output the torque to main drive wheels; a part-time-drive-wheel output shaft provided in parallel to the main-drive-wheel output shaft; a coupling provided on the main-drive-wheel output shaft and configured to extract a portion of the torque and output it to the part-time-drive-wheel output shaft via a transmission mechanism; and a damper disposed on the main-drive-wheel output shaft between the coupling and the transmission mechanism, wherein the coupling is provided with an input-side coupling part having a cylindrical shape, extending toward the transmission mechanism, and coupled to an inner circumferential part of the damper via a first spline-fitted section, the input-side coupling part of the coupling is coupled, via a second spline-fitted section, to an output-side coupling part of a drive force transmission member coupled to an outer circumferential part of the damper and configured to transmit a drive force to a driving-side transmission member of the transmission mechanism, the output-side coupling part having a cylindrical shape and extending toward the coupling, the second spline-fitted section allowing a relative rotation between the input-side coupling part and the output-side coupling part within a given angle, and the first and second spline-fitted sections are provided on an inner circumferential side of the damper, adjacently to each other in an axial direction of the main-drive-wheel output shaft.

2. The transfer structure of claim 1, wherein the drive force transmission member has a cylindrical part extending toward the transmission mechanism, a tip end portion of the cylindrical part is coupled to a cylindrical extension part provided to the driving-side transmission member of the transmission mechanism and extending toward the coupling, and a seal member attached to a transfer case is disposed at a root end side of the cylindrical part.

3. The transfer structure of claim 1, wherein the drive force transmission member is coupled to the outer circumferential part of the damper by using a bolt.

4. The transfer structure of claim 3, wherein an inner cylindrical member constituting the inner circumferential part of the damper is formed with an inner-cylindrical-side protrusion protruding outwardly, an outer cylindrical member constituting the outer circumferential part of the damper is formed with an outer-cylindrical-side protrusion protruding inwardly, an elastic member is sandwiched between the inner-cylindrical-side protrusion and the outer-cylindrical-side protrusion, and the outer-cylindrical-side protrusion is provided with a fastening section for the bolt that couples the outer circumferential part of the damper to the drive force transmission member.

5. The transfer structure of claim 1, wherein a seal member is provided between the first and second spline-fitted sections and the inner circumferential part of the damper to prevent entrance of lubrication oil from the first and second spline-fitted sections into the damper side.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic view illustrating a drive force transmission mechanism of a four-wheel drive vehicle on which a transfer device according to a first embodiment of the present disclosure is mounted.

(2) FIG. 2 is a cross-sectional view of the transfer device.

(3) FIG. 3 is an enlarged view of a main part of the transfer device.

(4) FIG. 4 is a cross-sectional view of a spline-fitted section between a coupling and a damper in an A-A cross section of FIG. 3.

(5) FIG. 5 is an enlarged view of a main part of a transfer device according to a second embodiment.

(6) FIG. 6 is a cross-sectional view of a damper in a B-B cross section of FIG. 5.

(7) FIG. 7 is an enlarged view of a main part of a transfer device according to a third embodiment.

(8) FIG. 8 is an enlarged view of a main part of the transfer device of the prior invention.

DETAILED DESCRIPTION OF THE DISCLOSURE

(9) Hereinafter, a transfer device of a vehicle according to the present disclosure is described in detail for each embodiment.

First Embodiment

(10) As illustrated in FIG. 1, the four-wheel drive vehicle 1 on which the transfer device according to a first embodiment is mounted is a four-wheel drive vehicle of a front-engine, rear-wheel drive base. The vehicle 1 includes an engine 2 (drive source) and a transmission 3 which are arranged in a front part of a vehicle body so that axes thereof extend in front-and-rear directions of the vehicle body (hereinafter, the front direction of the vehicle body may simply be referred to as the front side or forward and the rear direction of the vehicle body may simply be referred to as the rear side or rearward).

(11) A transfer device 10 is disposed rearward of the transmission 3 and outputs torque of the engine 2 transmitted from an output part of the transmission 3, to rear wheels (main drive wheels) via a rear-wheel propeller shaft extending rearwardly and a rear-wheel differential. The transfer device 10 also extracts a portion of the output torque for front wheels (part-time drive wheels).

(12) The transfer device 10 includes an input shaft 11, a rear-wheel output shaft 12, and a front-wheel output shaft 13. The input shaft 11 receives the output torque of the engine 2 at the front side (one side of an axial direction of the input shaft 11). The rear-wheel output shaft 12 is provided rearward of the input shaft 11 (the other side of the axial direction of the input shaft 11) and outputs the output torque of the engine 2 to the rear wheels. The front-wheel output shaft 13 is arranged in parallel to the rear-wheel output shaft 12, and outputs the output torque of the engine 2 to the front wheels. In this embodiment, the rear-wheel output shaft 12 is provided coaxially to the input shaft 11, is coupled to the input shaft 11, and outputs the output torque of the engine 2 to the rear wheels.

(13) The transfer device 10 also includes a coupling 20, a master gear 14, and a damper 30. The coupling 20 is provided on the rear-wheel output shaft 12 and coupled to the rear-wheel output shaft 12. The master gear 14 (driving-side transmission member) is provided forward of the coupling 20 and constitutes a transmission mechanism configured to transmit the output torque of the engine extracted by the coupling 20 to the front-wheel output shaft 13. The damper 30 is provided between the coupling 20 and the master gear 14. Further, a slave gear 15 (driven-side transmission member) is provided on the front-wheel output shaft 13, is fitted to the master gear 14, and constitutes the transmission mechanism.

(14) In this embodiment, the coupling 20 adopts an electromagnetic coupling to extract a portion of the output torque of the engine 2 to be outputted to the front wheels. The portion of the output torque of the engine 2 extracted by the coupling 20 (hereinafter, may simply referred to as front torque) is transmitted to the front-wheel output shaft 13 via the slave gear 15 meshing with the master gear 14.

(15) The front-wheel output shaft 13 is coupled, via a universal joint 40, to a front-wheel propeller shaft 50 extending forwardly. The front-wheel propeller shaft 50 is coupled to an input shaft 71 of a front-wheel differential 70 via a universal joint 60, and the input shaft 71 is coupled to drive axles 72 coupled to the left and right front wheels, respectively.

(16) Thus, the front torque extracted by the coupling 20 is transmitted to the front-wheel output shaft 13 via the master gear 14 and the slave gear 15, and further transmitted from the front-wheel output shaft 13 to the front wheels via the front-wheel propeller shaft 50 and the front-wheel differential 70. In the four-wheel drive vehicle 1, the coupling 20 is changeable of a ratio of the torque distribution to the front wheels and the rear wheels within a range between 0:100 and 50:50 (front wheels:rear wheels). Note that the operation of the coupling 20 is controlled by a control unit (not illustrated).

(17) Next, the transfer device 10 of this embodiment is described more in detail with reference to FIGS. 2 and 3.

(18) The rear-wheel output shaft 12 coupled to the input shaft 11 which receives the output of the transmission 3, and the front-wheel output shaft 13 disposed in parallel to the rear-wheel output shaft 12 are supported inside a transfer case 51 to be rotatable.

(19) The rear-wheel output shaft 12 has a recessed section 12b in a front end part 12a and is spline-fitted to the input shaft 11 which is inserted into the recessed section 12b, so as to rotate together with the input shaft 11. The rear-wheel output shaft 12 is coupled to a coupling member 7 by being spline-fitted thereto at a rear end part 12c, and is rotatably supported to the coupling 20 and the transfer case 51 via bearings 61 and 62. The coupling member 7 is coupled to the rear-wheel propeller shaft.

(20) Further, the master gear 14 includes a front extension part 14a and a rear extension part 14b which extend to the front side and the rear side, respectively, and is rotatably supported to the transfer case 51 via bearings 63 and 64.

(21) The slave gear 15 meshing with the master gear 14 is provided on the front-wheel output shaft 13 and supported to the transfer case 51 via bearings 65 and 66. Note that the transfer case 51 has a split structure including a first case member 52, a second case member 53, and a third case member 54 arranged in this order from the front side.

(22) The slave gear 15 is coupled to the front-wheel output shaft 13 by spline fitting. The front-wheel output shaft 13 is coupled to the front-wheel propeller shaft 50 via the universal joint 40, so that the drive force is transmittable.

(23) The coupling 20 includes the rear-wheel output shaft 12, a drum part 21, and a plurality of friction plates 23 disposed between the rear-wheel output shaft 12 and the drum part 21 and alternately spline-fitted to the rear-wheel output shaft 12 and the drum part 21. A cover member 24 is provided at a rear-side tip end of the drum part 21 of the coupling 20. A cam mechanism 25 configured to engage the plurality of friction plates 23, and a clutch mechanism 26 configured to operate the cam mechanism 25 by externally receiving a magnetic force, are provided between the plurality of friction plates 23 and the cover member 24.

(24) The coupling 20 further includes a solenoid 27 at the rear side of the cover member 24. Upon a power distribution control on the solenoid 27 by the control unit, the coupling 20 controls the engagement of the plurality of friction plates 23 via the clutch mechanism 26 and the cam mechanism 25. Thus, the front torque is variably controlled and extracted.

(25) The solenoid 27 is fixed to the transfer case 51 via a cylindrical support member 28 supporting the solenoid 27, and the coupling 20 is rotatably supported at the rear side to the transfer case 51 via a bearing 29.

(26) As illustrated in FIG. 3, the damper 30 includes an outer cylindrical member 31 forming an outer circumferential part of the damper 30, an inner cylindrical member 32 forming an inner circumferential part of the damper 30, and an elastic member 33 provided between the outer and inner cylindrical members 31 and 32 to couple them with each other.

(27) An anti-projection member 34 configured to prevent projection of the elastic member 33, which is disposed between the outer and inner cylindrical members 31 and 32 of the damper 30, from the disposed position is provided on one side surface of the damper 30 on the coupling 20 side. At the anti-projection member 34 and an end part of the outer cylindrical member 31 of the damper 30, a snap ring 35 prevents slip-out of the anti-projection member 34 from the outer cylindrical member 31.

(28) The damper 30 reduces a resonance frequency at which a front-wheel drivetrain resonates with a torque variation of the engine 2, to be below a practical range of the engine 2. The front-wheel drivetrain extends from the coupling 20 to the front wheels via the master gear 14, the slave gear 15, the front-wheel output shaft 13, the front-wheel propeller shaft 50, and the front-wheel differential 70.

(29) Next, a coupling structure among the coupling 20, the damper 30, and the master gear 14, and a coupling structure between the coupling 20 and the master drive 14 are described.

(30) The drum part 21 of the coupling 20 is provided with a cylindrical input-side coupling part 22 extending to the master gear 14 side, and the input-side coupling part 22 is coupled to the inner cylindrical member 32 of the damper 30 via a first spline-fitted section S1.

(31) A drive force transmission member 81 is fitted to an end part of the outer cylindrical member 31 of the damper 30 on the master gear 14 by comb teeth or by spline-fitting, and slip-out of the drive force transmission member 81 from the outer cylindrical member 31 is prevented by a snap ring 82.

(32) Further, the drive force transmission member 81 is provided, at its inner circumferential side, with a cylindrical part 81a and an output-side coupling part 81b having a cylindrical shape. The cylindrical part 81a extends toward the master gear 14 and is spline-fitted to the inner circumferential side of the rear extension part 14b constituting an input part of the master gear 14. The output-side coupling part 81b extends to the coupling 20 side and is coupled to the input-side coupling part 22, which is provided to the coupling 20, via a second spline-fitted section S2 where a relative rotation within a given angle is allowed.

(33) Here, the first and second spline-fitted sections S1 and S2 are described in detail.

(34) In the first spline-fitted section S1, a backlash between spline teeth 22 on an outer circumferential surface of the input-side coupling part 22 of the coupling 20 and spline teeth 32 on an inner circumferential surface of the inner cylindrical member 32 of the damper 30 is set small. Thus, the relative rotation between the coupling 20 and the inner cylindrical member 32 is zero or substantially zero.

(35) On the other hand, in the second spline-fitted section S2, as illustrated in FIG. 4, a backlash between the spline teeth 22 on the outer circumferential surface of the input-side coupling part 22 of the coupling 20 and spline teeth 81b on an inner circumferential surface of the output-side coupling part 81b of the drive force transmission member 81 is set large. Thus, the relative rotation between the coupling 20 and the drive force transmission member 81 within the given angle is allowed.

(36) For example, the adjacent spline teeth 81b and the adjacent spline teeth 22 have a relationship such that a large backlash L is provided between the spline tooth 81b and the spline tooth 22 fitted to each other, on a clockwise side F of a tooth surface the spline tooth 22. Note that the clockwise side F corresponds to a rotating direction F of the coupling 20 and the drive force transmission member 81 at the time of forward drive, which is when the torque is transmitted from the input-side coupling part 22 of the coupling 20 to the output-side coupling part 81b of the drive force transmission member 81. Thus, the output- and input-side coupling parts 81b and 22 are allowed to rotate in relation to each other within the given angle at the time of forward drive.

(37) Note that the first and second spline-fitted sections S1 and S2, which are formed on the outer circumferential side of the input-side coupling part 22 of the coupling 20, are adjacent to each other in the axial direction of the rear-wheel output shaft 12, on the inner circumferential side of the damper 30. The spline teeth 32 of the inner cylindrical member 32 of the damper 30 and the spline teeth 81b of the output-side coupling part 81b of the drive force transmission member are disposed to mesh with the common spline teeth 22 of the input-side coupling part 22 of the coupling 20.

(38) With such a structure, when the front torque extracted by the coupling 20 is lower than the given value, the deformation of the elastic member 33 of the damper 30 is small and the relative rotation of the inner cylindrical member 32 to the outer cylindrical member 31 of the damper 30 is small. Therefore, in the second spline-fitted section S2 with the large backlash, the spline teeth 81b do not meet in contact with the spline teeth 22, and the torque is not transmitted. Thus, the torque is transmitted from the coupling 20 to the master gear 14 via the first spline-fitted section S1, the damper 30, and the drive force transmission member 81.

(39) On the other hand, when the front torque extracted by the coupling 20 is higher than the given value, the deformation of the elastic member 33 of the damper 30 is large and the relative rotation of the inner cylindrical member 32 to the outer cylindrical member 31 is large. Therefore, also in the second spline-fitted section S2 with the large backlash, the spline teeth 81b meet in contact with the spline teeth 22, and the torque is transmitted. Thus, the torque is transmitted from the coupling 20 to the master gear 14 via the first spline-fitted section S1, the damper 30, and the drive force transmission member 81, and also via the cylindrical part 81a of the drive force transmission member 81.

(40) Here, the second spline-fitted section S2, which is the section where the input-side coupling part 22 of the coupling 20 and the output-side coupling part 81b of the drive force transmission member 81 are spline-fitted, functions as a stopper mechanism configured to regulate the relative rotational amount of the damper 30. Thus, application of torque above the given value to the damper 30 is avoided.

(41) Next, the damper structure is described more in detail by using FIG. 6 which illustrates a second embodiment.

(42) A plurality of outer-cylindrical-side protrusions 31a are formed inwardly at an inner circumferential side of the outer cylindrical member 31 of the damper 30 at even intervals in a circumferential direction thereof. Further, a plurality of inner-cylindrical-side protrusions 32a are formed outwardly at an outer circumferential side of the inner cylindrical member 32 of the damper 30 at even intervals in a circumferential direction thereof. The protrusions 31a and 32a are located alternately to each other.

(43) The elastic member 33 of the damper 30 is formed using an elastic material (e.g., natural rubber, synthetic rubber, etc.) and divided into first elastic members 33a and second elastic members 33b, each member being sandwiched between the adjacent protrusions 31a and 32a. Further, a rotating direction of the damper 30 at the time of forward drive, which is when the torque extracted by the coupling 20 is transmitted from the inner cylindrical member 32 toward the outer cylindrical member 31 of the damper 30 via the elastic member 33 of the damper 30, is the arrow F direction illustrated in the drawing. Each first elastic member 33a disposed on the advancing side of the inner-cylindrical-side protrusion 32a in the rotating direction at such time of the forward drive has a larger volume than that of the second elastic member 33b disposed on the reverse side of the inner-cylindrical-side protrusion 32a in the rotating direction. That is, the first elastic members 33a located on the compressed side at the time of the forward drive, which is frequently performed when the vehicle travels, is provided to have a higher vibration damping ability.

(44) Transfer devices generally include a transmission mechanism, bearings, a spline-fitted section, etc. which require lubrication, and therefore in this embodiment, seal members 91 to 93 are provided in order to prevent leakage of the lubrication oil for lubrication of these components to the outside of the transfer device 10, electric components inside the transfer case 51, etc.

(45) As illustrated in FIG. 3, the transfer device 10 has a first space which accommodates the transmission mechanism which requires lubrication, and a second space which accommodates the coupling 20 and the damper 30 and where electromagnetic components connected to the outside from the transfer case 51 are provided. These spaces are partitioned by the oil seal 91 which prevents leakage of the lubrication oil from the first space to the second space.

(46) The oil seal 91 attached to the transfer case 51 is disposed on the coupling 20 side of a portion 81a of the cylindrical part 81a of the drive force transmission member coupled to the input part 14b of the master gear. Thus, only the cylindrical part 81a of the drive force transmission member exists between the rear-wheel output shaft 12 and the oil seal 91. Therefore, the radius of a lip part 91a of the oil seal 91 in contact with the cylindrical part 81a is reduced and a sliding speed of the rear-wheel output shaft 12 on the lip part 91a is reduced. As a result, the durability of the oil seal 91 improves.

(47) The lip seal 92 is provided between the first spline-fitted section S1 formed between the inner cylindrical member 32 of the damper 30 and the input-side coupling part 22 of the coupling 20, and the second spline-fitted section S2 formed between the output-side coupling part 81b of the drive force transmission member and the input-side coupling part 22 of the coupling 20. The lip seal 92 is attached to the inner cylindrical member 32 to be in contact with one side surface of the output-side coupling part 81b on the coupling 20 side. Thus, entrance of the lubrication oil into separate spaces on the outer circumferential side of the output-side coupling part 81b and the inner circumferential side of the inner cylindrical member 32 of the damper 30 is prevented. Therefore, while supplying the lubrication oil to the first spline-fitted section S1 and the second spline-fitted section S2, the entrance of the lubrication oil into the elastic member 33 of the damper 30 is prevented.

(48) Further, an O-ring 93 is fixed to the inner cylindrical member 32 and the input-side coupling part 22 of the coupling 20 at a position on the coupling 20 side of the first spline-fitted section S1, by being sandwiched therebetween. The O-ring 93, while the lubrication oil is supplied to the first spline-fitted section S1, prevents both leakage of the lubrication oil to the elastic member 33 side and leakage of the lubrication oil toward the space where the coupling is accommodated.

(49) In the transfer device 10 having the above structure, the output torque of the engine 2 inputted to the input shaft 11 is transmitted to the rear-wheel output shaft 12. In the two-wheel drive state, the output torque is then outputted from the rear-wheel output shaft 12 to the rear wheels alone. In the four-wheel drive state, the output torque is outputted from the rear-wheel output shaft 12 to the rear wheels and also the front torque is extracted from the output torque by the coupling 20 and outputted to the front wheels.

(50) When the front torque extracted by the coupling 20 is below the given value, the front torque is transmitted from the coupling 20 to the master gear 14 via the damper 30. The front torque is further outputted from the master gear 14 to the front wheels via the slave gear 15, the front-wheel output shaft 13, the front-wheel propeller shaft 50, and the front-wheel differential 70.

(51) Here, the resonance frequency at which the front-wheel drivetrain resonates with the torque variation of the engine 2 is reduced to be below the practical range of the engine 2 by the damper 30. Thus, the teeth rattling noise between gears (e.g., between the master gear 14 and the slave gear 15), which may occur when the front torque extracted by the coupling 20 is comparatively low, is reduced.

(52) In the transfer device 10 of this embodiment, when the torque transmitted from the coupling 20 to the master gear 14 side is small, the torque is transmitted from the input-side coupling part 22, which is provided to the coupling 20, to the first spline-fitted section S1, the damper 30 and the drive force transmission member 81. When the torque is large, the angle of the relative rotation of the inner cylindrical member 32 with respect to the outer cylindrical member 31 of the damper 30 increases to bring the second spline-fitted section S2 into a torque transmittable state. A part of the torque is transmitted from the input-side coupling part 22 directly to the output-side coupling part 81b provided to the drive force transmission member 81 via the second spline-fitted section S2.

(53) Thus, the second spline-fitted section S2 functions as the stopper mechanism configured to regulate the relative rotation amount of the damper 30. Therefore, the torque input higher than the given value to the damper 30 is prevented, and while the damper 30 reduces the teeth rattling noise without increasing fuel consumption, the durability of the damper 30 is secured.

(54) Moreover, the first and second spline-fitted sections S1 and S2 are formed on the rear-wheel output shaft 12 adjacent to each other in the axial direction. Therefore, the cylindrical part 81a provided to the drive force transmission member 81 and coupling the outer circumferential part of the damper 30 to the master gear 14 to transmit torque from the damper 30 to the master gear 14, is disposed, in the axial direction of the drive force transmission member 81, opposite from the output-side coupling part 81b constituting the second spline-fitted section S2. Thus, the structure between the damper 30 and the master gear 14 is simplified. As a result, a size increase of the transfer device 10 which is caused by positions where two functions of the torque transmission from the coupling 20 and the torque transmission to the master gear 14 are exerted overlapping in the axial direction of the damper 30 is prevented, and further the transfer device 10 is downsized. Additionally, by providing the damper 30, the teeth rattling noise is reduced without increasing fuel consumption.

Second Embodiment

(55) A transfer structure according to a second embodiment is described with reference to FIG. 5. Note that the components similar to those in the first embodiment illustrated in FIG. 3 are assigned with the same reference characters in FIG. 5, and description thereof is omitted.

(56) In the second embodiment, a coupling structure between an outer cylindrical member 131 of a damper 130 and a drive force transmission member 181, and a coupling structure between the outer cylindrical member 131 and an anti-projection member 134 for an elastic member 133 are different from those in the first embodiment. Note that other structures and configurations are similar to those in the first embodiment, and similar effects to those in the first embodiment are obtained.

(57) In the transfer device of the second embodiment, similar to the first embodiment, the damper 130 is provided between a coupling 20 and a transmission mechanism provided on a rear-wheel output shaft 12. Further an input-side coupling part 22 provided to the coupling 20 is coupled to an inner-cylindrical member 132 of the damper 130 via a first spline-fitted section S1. Moreover, an output-side coupling part 181b provided to the drive force transmission member 181 is coupled to the input-side coupling part 22 of the coupling 20 via a second spline-fitted section S2 while allowing a relative rotation within a given angle. The drive force transmission member 181 is coupled to the outer cylindrical member 131 of the damper 130 and transmits drive force to the transmission mechanism.

(58) Similar to the first embodiment, the first and second spline-fitted sections S1 and S2 are disposed on the rear-wheel output shaft 12 to be adjacent to each other in the axial direction thereof. Thus, a drive force transmitting structure from the damper 130 to the master gear 14, and the second spline-fitted section S2 are disposed opposite from each other in the axial direction of the drive force transmission member 181.

(59) In the second embodiment, the drive force transmission member 181 and the anti-projection member 134 provided to one side surface of the damper 130 on the coupling 20 side and configured to prevent projection of the elastic member 133 are fastened to fastening sections 131a by bolts 131b and 134a. The fastening sections 131a are formed in outer-cylindrical-side protrusions 131a provided to the outer cylindrical member 131 of the damper 130. Further, a plurality of inner-cylindrical-side protrusions 132a are formed outwardly at an outer circumferential side of the inner-cylindrical member 132 of the damper 130 at even intervals in a circumferential direction thereof. The protrusions 131a and 132a are located alternately to each other.

(60) With such a structure, similar to the first embodiment, in the transfer structure which is mounted on the four-wheel drive vehicle, the effect of preventing the size increase of the transfer device while providing the damper to reduce the teeth rattling noise without increasing fuel consumption is obtained.

(61) Particularly in the second embodiment, rattling of the damper 130 is reduced and the damping performance is secured more reliably, compared to a case where the outer cylindrical member 131 of the damper 130 and the drive force transmission member 181 are fitted in manner of spline-fitting, comb teeth, etc. Further, since the bolts 131b and 134a are fastened to the outer-cylindrical-side protrusions 131a provided in the outer cylindrical member 131 of the damper 130, fastening sections dedicated for the fastening are not separately required.

Third Embodiment

(62) A transfer structure according to a third embodiment is described with reference to FIG. 7. Note that the components similar to those in the first embodiment illustrated in FIG. 3 are assigned with the same reference characters in FIG. 7, and description thereof is omitted.

(63) In the third embodiment, a coupling structure between an outer cylindrical member 231 of a damper 230 and a drive force transmission member 281, and structures of coupling and seal parts between a coupling 220 and the damper 230 are different from those in the first embodiment. Note that other structures and configurations are similar to those in the first embodiment, and similar effects to those in the first embodiment are obtained.

(64) As illustrated in FIG. 7, the transfer device of the third embodiment, similar to the first embodiment, includes the damper 230 between the coupling 220 provided on a rear-wheel output shaft 12. A first input-side coupling part 222a extending from a drum part 221 of the coupling 220 to a master gear 14 side is coupled at its outer circumferential side to an inner cylindrical member 232 of the damper 230 via a first spline-fitted section S1. A second input-side coupling part 222b located on the master gear 14 side of the first input-side coupling part 222a of the coupling 220 and having a smaller diameter than the first input-side coupling part 222a is coupled to an output-side coupling part 281b via a second spline-fitted section S2. The output-side coupling part 281b extends toward the coupling 220 from the inner circumferential side of the drive force transmission member 281 coupled, by bolts 231b, to fastening sections 231a of inward protrusions 231a provided in the outer cylindrical member 231 of the damper 230. Further, a cylindrical part 281a spline-fitted to an inner circumferential side of a rear extension part 14b constituting an input part of the master gear 14 is provided to extend to the master gear 14 side. Note that the first spline-fitted section S1 is provided with a snap ring 232a as a retainer of the damper 230 which prevents slip-out thereof from the coupling 220.

(65) Further, a seal member 292 is attached to an inner circumferential part of the inner cylindrical member 232. The seal member 292 is provided so that both sides are in contact with a vertical wall 222a of the first input-side coupling part 222a of the coupling 220 and a side surface 281b of the output-side coupling part 281b of the drive force transmission member 281, respectively.

(66) With such a structure, similar to the first embodiment, in the transfer structure which is mounted on the four-wheel drive vehicle, the size increase of the transfer device is prevented while providing the damper to reduce the teeth rattling noise without increasing fuel consumption.

(67) Particularly in the third embodiment, while supplying the lubrication oil to the second spline-fitted section S2 which requires lubrication, the entrance of the lubrication oil into an elastic member 233 of the damper 230 from the second spline-fitted section S2 and the entrance of the lubrication oil thereto via the first spline-fitted section S1 are prevented. Further, by forming the first and second spline-fitted sections S1 and S2 at the first and second input-side coupling parts 222a and 222b of the coupling 220, respectively, seal members are put together into a single member, the damper structure is simplified, and the transfer device is downsized.

(68) Note that the transmission mechanism of the present disclosure is not limited to that using gears, and it may be a winding mechanism. In this case, as the transmission member, a sprocket and a pulley are provided instead of the master gear and the slave gear.

(69) The present disclosure is not limited to the above illustrative embodiments, and various enhancements and various modifications in design are made without departing from the scope of the present disclosure.

(70) As described above, according to the present disclosure, in a transfer structure which is mounted on a four-wheel drive vehicle, a size increase of the transfer device is prevented while providing a damper to reduce the teeth rattling noise without increasing fuel consumption. Therefore, the present disclosure may suitably be used in the fields of manufacturing industries of this type of four-wheel drive vehicles.

(71) It should be understood that the embodiments herein are illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof, are therefore intended to be embraced by the claims.

DESCRIPTION OF REFERENCE CHARACTERS

(72) 1 Four-wheel Drive Vehicle 2 Engine 3 Transmission 10 Transfer Device 11 Input Shaft 12 Rear-wheel Output Shaft (Main-drive-wheel Output Shaft) 13 Front-wheel Output Shaft (Part-time-drive-wheel Output Shaft) 14 Master Gear (Driving-side Transmission Member) 14b Input Part 15 Slave Gear 20 Coupling 22 Input-side Coupling Part 30 Damper 31 Outer Cylindrical Member 31a Outer-cylindrical-side Protrusion 32 Inner Cylindrical Member 32a Inner-cylindrical-side Protrusion 33 Elastic Member 51 Transfer Case 81 Drive Force Transmission Member 81a Cylindrical Part 81b Output-side Coupling Part 91 Oil Seal 92 Lip Seal 93 O-ring S1 First Spline-fitted Section S2 Second Spline-fitted Section