JP2021160615A - Power transmission device - Google Patents

Abstract

To provide a power transmission device for a vehicle comprising a main driving wheel and a sub driving wheel, which can suppress gear rattle and can be reduced in manufacturing process and reduced in cost.SOLUTION: A power transmission device comprises a main-driving wheel driving part 20 and a sub-driving wheel driving wheel part 30 having a power extraction part 40. The power extraction part 40 has: a drive gear 43 communicated with the main-driving wheel driving part 20; a driven gear 44 that engages with the drive gear 43 and transmits power to a sub-driving wheel 4; a damper 80, provided on a power transmission passage leading from the main-driving wheel driving part 20 to the drive gear 43, which comprises an inner cylinder part 82, an outer cylinder part 84 and an elastic member 93; a power transmission shaft 46 that supports the drive gear 43 and has a large diameter part 46a and a small diameter part 46c arranged at an outer periphery side of the outer cylinder part 84; and an input shaft 41 forming a damper arrangement space S between the shaft and the power transmission shaft 46. The input shaft 41 is formed integrally with the inner cylinder part 82 and is connected to the large diameter part 46a through a spline having a backlash.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power transmission device for a vehicle including a main drive wheel and an auxiliary drive wheel.

Generally, a power transmission device for a four-wheel drive vehicle that can be switched between a two-wheel drive state and a four-wheel drive state includes a main drive wheel drive unit that transmits output torque from a drive source to the main drive wheels and an auxiliary drive wheel. It has an auxiliary drive wheel drive unit provided with a power extraction unit that extracts torque transmitted to the main drive wheel drive unit from the main drive wheel drive unit.

For example, in the case of a so-called FF (front engine / front drive) -based four-wheel drive vehicle in which the engine as a drive source is mounted on the front part of the vehicle body and the main drive wheels are the front wheels, a power transmission device is provided on the front wheels. The output torque of the engine is transmitted via the constituent transmissions, the front wheel differential device constituting the front wheel (main drive wheel) drive unit, and the pair of left and right drive shafts. For the rear wheels, the torque input to the front wheel drive unit is taken out by the transfer device as the power take-out part via the differential case of the front wheel differential device, and the torque taken out by the power take-out part is taken out by the propeller for the rear wheels. It is transmitted via a shaft, a rear wheel differential, and a pair of left and right drive shafts. The power take-out unit, the propeller shaft for the rear wheels, the differential device for the rear wheels, and the pair of left and right drive shafts constitute the rear wheel (secondary drive wheel) drive unit.

The power take-out portion is composed of bevel gears that mesh with each other in order to transmit torque from a front wheel differential whose axis extends in the vehicle body width direction to a rear wheel propeller shaft whose axis extends in the vehicle body front-rear direction. Has a transfer gear set. The transfer gear set includes a transfer drive gear arranged on the axis of the front wheel differential device and a transfer driven gear provided on the axis of the propeller shaft.

By the way, in the four-wheel drive vehicle, the four-wheel drive state in which the front wheels and the rear wheels are driven is driven according to the distribution of the output torque of the engine to the rear wheels, as compared with the two-wheel drive state in which only the front wheels are driven. Since the loss increases and the fuel consumption deteriorates, the vehicle is normally driven in a two-wheel drive state and, if necessary, in a four-wheel drive state.

However, the output torque fluctuation of the engine is transmitted to the power take-out part via the transmission and the front wheel differential device, and in the two-wheel drive state, the propeller shaft and the rear wheel differential from the transfer gear set to the rear wheel in the power take-out part. The rear wheel drive unit of the device or the like rotates in a non-power transmission state in which torque is not transmitted.

Therefore, depending on the frequency of the torque fluctuation of the engine, the rear wheel drive unit having a predetermined natural frequency with respect to the torsional vibration resonates with the torque fluctuation of the engine, and the vibration of the rear wheel drive unit becomes large, and this vibration becomes large. As a result, abnormal noise or the like due to tooth striking between the transfer drive gear and the transfer driven gear may occur, causing noise in the vehicle interior.

Therefore, for example, as disclosed in Patent Document 1, a damper is placed on the power transmission path from the front wheel drive unit to the transfer drive gear (from the input shaft of the power take-out unit connected to the front wheel differential device to the transfer drive gear). It is being studied to suppress the rattling noise in the two-wheel drive state by providing it. In this case, by reducing the torsional rigidity of the rear wheel drive unit, the natural frequency of the rear wheel drive unit is set to a vibration range that does not resonate with torque fluctuations that may occur in the normal range of engine rotation speed. It becomes possible to shift.

Japanese Unexamined Patent Publication No. 2018-11130

The power take-out portion provided with the damper provided on the power transmission path disclosed in Patent Document 1 is arranged on the outer peripheral side of the cylindrical input shaft extending in the vehicle body width direction and on the input shaft. A damper that is arranged between the input shaft and the power transmission shaft and has an inner cylinder portion, an outer cylinder portion, and an elastic member such as a tubular rubber that is interposed between them. Be prepared. A transfer drive gear is provided on the power transmission shaft.

The input torque transmission path input to the transfer device is a first transmission path that allows the input torque to pass through the damper when the input torque is less than a predetermined value, and a second transmission path that does not pass through the damper when the input torque is greater than or equal to the predetermined value. It has a transmission path of.

The first transmission path is a path that passes through the input shaft, the spline fitting portion between the input shaft and the inner cylinder portion of the damper, the inner cylinder portion, the elastic member, the outer cylinder portion, and the power transmission shaft. The second transmission path is a path that passes through the input shaft, the spline fitting portion between the input shaft and the power transmission shaft, and the power transmission shaft.

Since the input shaft and the inner cylinder portion of the damper are spline-fitted as described above, the diameter of the input shaft is preferably close to the diameter of the inner cylinder portion, and the diameter is smaller than that of the outer cylinder portion of the damper. On the other hand, the power transmission shaft has a large diameter portion having a larger diameter than the outer cylinder portion for press-fitting into the outer cylinder portion of the damper and a small diameter portion having a smaller diameter than the large diameter portion for spline fitting to the input shaft. A part is provided.

As described above, since the spline fitting portion between the input shaft and the power transmission shaft is provided in the small diameter portion, the number of spline teeth formed in the spline fitting portion is small, and the spline fitting portion has a small number of spline teeth. The strength corresponding to the required surface pressure may be insufficient. In this case, it is conceivable that the spline fitting portion is subjected to a heat treatment such as charcoal burning to ensure the strength corresponding to the surface pressure required for the spline fitting portion. However, this increases the processing man-hours and costs of the transfer device. That is, there is room for improvement from the viewpoint of manufacturing and cost of the transfer device.

Therefore, it is an object of the present invention to reduce the manufacturing process and the cost while suppressing the rattling noise in the power transmission device of the vehicle provided with the main drive wheel and the sub drive wheel.

In order to solve the above problems, the power transmission device according to the present invention is characterized by being configured as follows.

The power transmission device according to the invention according to claim 1 of the present application is
A main drive wheel drive unit for transmitting power from the drive source to the main drive wheels,
A power transmission device including an auxiliary drive wheel drive unit having a power extraction unit for extracting power transmitted to the auxiliary drive wheels from the main drive wheel drive unit.
The power take-out unit is
A transfer gear set including a transfer drive gear connected to the main drive wheel drive unit and a transfer-driven gear that meshes with the transfer drive gear and transmits power to the auxiliary drive wheels.
A damper provided on the power transmission path from the main drive wheel drive unit to the transfer drive gear, and an elastic member interposed between the inner cylinder portion, the outer cylinder portion, and both cylinder portions.
A power transmission shaft that supports the transfer drive gear and has a large-diameter portion arranged on the outer peripheral side of the outer cylinder portion and a small-diameter portion smaller than the large-diameter portion.
It has an input shaft that extends from the inner peripheral portion of the small diameter portion toward the large diameter portion and forms a damper arrangement space with the power transmission shaft.
The input shaft is formed integrally with the inner cylinder portion, and is characterized in that it extends outward in the radial direction and is connected to the large diameter portion of the power transmission shaft via a spline having backlash. do.

The invention according to claim 2 is the invention according to claim 1.
The outer cylinder portion and the power transmission shaft are spline-fitted in the vicinity of the spline fitting portion between the power transmission shaft and the input shaft.

The invention according to claim 3 is the invention according to claim 1 or 2.
The internal teeth formed on the power transmission shaft of the spline fitting portion between the power transmission shaft and the input shaft and the spline fitting portion between the power transmission shaft and the outer cylinder portion of the damper are , It is characterized by being formed by a common spline.

The invention according to claim 4 is the invention according to any one of claims 1 to 3.
The main drive wheel is arranged on the power source side of the vehicle body, and the sub drive wheel is arranged on the reaction power source side of the vehicle body.

The invention according to claim 5 is the invention according to any one of claims 1 to 4.
The first damper is characterized in that it is arranged so as to overlap the transfer gear in the axial direction of the input shaft.

According to the power transmission device according to the invention of claim 1, since a damper is provided between the input shaft and the power transmission shaft, the torsional rigidity of the auxiliary drive wheel drive unit is reduced. As a result, the natural frequency of the auxiliary drive wheel drive unit can be shifted to a vibration range that does not resonate with torque fluctuations that may occur in the normal range of the engine speed.

Since the input shaft and the inner cylinder portion of the damper are integrally formed, the spline fitting portion between the input shaft and the inner cylinder portion can be reduced. As a result, it is possible to reduce the processing man-hours for processing the spline and shorten the axial dimension of the power transmission shaft.

Since the spline fitting portion between the input shaft and the power transmission shaft is provided in the large diameter portion of the power transmission shaft, it is easy to secure the strength corresponding to the surface pressure required for the spline fitting portion. Therefore, for example, in order to secure the strength corresponding to the surface pressure required for the spline fitting portion, the spline fitting portion is subjected to a heat treatment such as charcoal burning or the axial length of the spline fitting portion is extended. There is no need to do it.

From the above, in the power transmission device of the vehicle provided with the main drive wheel and the auxiliary drive wheel, it is possible to reduce the manufacturing process and the cost while suppressing the rattling noise.

According to the second aspect of the present invention, the outer cylinder portion of the damper is spline-coupled to the power transmission shaft in the vicinity of the spline fitting portion of the power transmission shaft and the input shaft via backlash. Therefore, the spline fitting portions can be centrally arranged. This makes it easy to process the spline fitting portion.

According to the third aspect of the invention, there is a spline fitting portion between the power transmission shaft and the input shaft, and a spline fitting portion between the power transmission shaft and the outer cylinder portion of the damper. Since the spline teeth of the power transmission shaft are formed of a common spline, each spline tooth of the two spline fitting portions of the power transmission shaft can be formed by one processing.

According to the invention of claim 4, the front wheel drive state of a so-called FF (front engine / front drive) -based four-wheel drive vehicle, or the rear wheels of an RR (rear engine / rear drive) -based four-wheel drive vehicle. In the driving state, the natural frequency of the sub-drive wheel drive unit can be shifted to a vibration range that does not resonate with torque fluctuations that may occur in the normal range of the engine speed. As a result, the rattling noise at each meshing portion of the auxiliary drive wheel drive portion can be effectively suppressed.

Further, since the spline fitting portion between the input shaft and the power transmission shaft is provided in the large diameter portion of the power transmission shaft, the axial length of the spline fitting portion is longer than that in the case of providing the spline fitting portion in the small diameter portion. It is easy to shorten the axial dimension of the power take-out part. As a result, the front-wheel drive state of the so-called FF (front engine / front drive) -based four-wheel drive vehicle, or the RR (rear engine / rear drive) -based four-wheel drive vehicle, which is required to be compact in the width direction of the vehicle body, is required. A more pronounced effect is obtained in the rear wheel drive state.

According to the invention of claim 5, since the first damper is arranged so as to overlap the transfer gear in the axial direction of the input shaft, the axial dimension of the power take-out portion should be made compact. Can be done.

It is a skeleton diagram of the vehicle provided with the power transmission device which concerns on embodiment of this invention. It is sectional drawing which shows the damper and its peripheral part in the power take-out part of the power transmission device. FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2 when a part of the power take-out portion of the power transmission device is viewed from the axial direction. FIG. 2 is a sectional view taken along line IV-IV of FIG. 2 when a part of the power take-out portion of the power transmission device is viewed from the axial direction.

Hereinafter, a specific configuration of the vehicle provided with the power transmission device according to the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the vehicle 1 provided with the power transmission devices 8, 20 and 30 according to the present embodiment has left and right front wheels 2 as main drive wheels and left and right rear wheels 4 as auxiliary drive wheels. It is a so-called FF (front engine / front drive) -based four-wheel drive vehicle, and can be switched between a front-wheel drive state and a four-wheel drive state.

(FF 4WD)
The vehicle 1 includes an engine 6 as a drive source. The engine 6 is a transverse type and is arranged in an engine room in the front portion of the vehicle 1. A transaxle 8 constituting a power transmission device is juxtaposed on one side (for example, the left side of the vehicle body) of the engine 6 in the vehicle body width direction. The transaxle 8 includes, for example, a transmission (not shown) connected to the output shaft of the engine 6 via a torque converter (not shown) and front wheels connected to an output gear 9 as an output unit of the transmission. The differential device 10 is provided.

The power transmission devices 8, 20, and 30 include a front wheel (main drive wheel) drive unit 20 that transmits the output torque from the engine 6 to the front wheels 2, and a front wheel (main drive wheel) drive unit 20 that transmits the torque transmitted to the rear wheels 4. A rear wheel (secondary drive wheel) drive unit 30 including a transfer device 40 as a power take-out unit to be taken out from is provided.

The front wheels 2 are connected to the engine 6 via front wheel drive shafts 21 and 22, front wheel differential device 10, the transmission, and the like. The front wheel (main drive wheel) drive unit 20 includes a front wheel differential device 10 and front wheel drive shafts 21 and 22. The front wheels 2 are connected to the engine 6 without going through the coupling 60 described later, and power is transmitted from the engine 6 to the front wheels 2 in both the engaged state and the released state of the coupling 60.

The front wheel drive shafts 21 and 22 are arranged so as to extend in the vehicle body width direction. The front wheel drive shafts 21 and 22 are composed of a plurality of shaft members connected via, for example, a pair of universal joints 23 and 24.

The front wheel differential device 10 includes a differential ring gear 11 that meshes with the output gear 9 of the transmission, a differential case 12 to which the differential ring gear 11 is fixed or integrally provided, and left and right side gears 18 and 19 housed in the differential case 12. I have.

One ends of the front wheel drive shafts 21 and 22 are connected to the side gears 18 and 19 of the front wheel differential device 10 so as to rotate together with the side gears 18 and 19 by, for example, spline fitting. The power transmitted from the output gear 9 of the transmission to the differential case 12 of the front wheel differential device 10 via the differential ring gear 11 is applied to the left and right front wheel drive shafts 21 and 22 so as to have a rotation difference according to the traveling situation. Be transmitted.

On the other hand, the rear wheels 4 include rear wheel drive shafts 31 and 32, rear wheel differential device 70, coupling 60, propeller shaft 50, transfer device 40, front wheel differential device 10, differential case 12, and the transmission. It is connected to the engine 6 via. The rear wheel drive unit 30 includes a transfer device 40, a propeller shaft 50, a coupling 60, a rear wheel differential device 70, and rear wheel drive shafts 31 and 32.

The rear wheel drive shafts 31 and 32 are arranged so as to extend in the vehicle body width direction. The rear wheel drive shafts 31 and 32 are composed of a plurality of shaft members connected via, for example, a pair of universal joints 33 and 34.

Like the front wheel differential device 10, the rear wheel differential device 70 includes a differential ring gear 71, a differential case 72, and left and right side gears 78 and 79. One ends of the rear wheel drive shafts 31 and 32 are connected to the side gears 78 and 79 so as to rotate together with the side gears 78 and 79, for example, by spline fitting.

The coupling 60 includes an input shaft 61, an output shaft 62, and a plurality of friction plates 63 for connecting the input shaft 61 and the output shaft 62 in a connectable manner. The coupling 60 is, for example, an electronically controlled coupling, and torque distribution between the front and rear wheels is performed by controlling the fastening force between the friction plates 63. The torque distribution (front wheels: rear wheels) can be controlled in the range of, for example, 50:50 to 100: 0.

The input shaft 61 of the coupling 60 is arranged on an axis extending in the front-rear direction of the vehicle body. The input shaft 61 is connected to the rear end of the propeller shaft 50, which is a rotating member on the engine 6 side of the coupling 60.

The plurality of friction plates 63 are composed of, for example, a wet multi-plate clutch. A fastening force is applied to the plurality of friction plates 63 by pressing with a piston (not shown). The piston is operated, for example, via an electromagnetic clutch and a cam mechanism.

The output shaft 62 of the coupling 60 is arranged on the same axis as the input shaft 61 on the rear side of the vehicle body with respect to the input shaft 61. A pinion gear 64 is provided at the rear end of the output shaft 62. The pinion gear 64 meshes with the differential ring gear 71 of the rear wheel differential 70. As a result, the output shaft 62 is connected to the differential case 12, which is a rotating member on the rear wheel 4 side of the coupling 60, via the meshing portion between the pinion gear 64 and the differential ring gear 71.

The pinion gear 64 and the differential gear 71 are made of a bevel gear such as a hypoid gear. The axis of the pinion gear 64 is offset below the axis of the differential ring gear 71 in the vertical direction of the vehicle body. The differential ring gear 71 has a larger diameter than the pinion gear 64. As a result, the rotation of the output shaft 62 of the coupling 60 is decelerated and transmitted to the differential case 72 of the rear wheel differential device 70.

The propeller shaft 50 transmits the power taken out by the transfer device 40 to the rear wheel 4 side. The propeller shaft 50 is arranged so as to extend in the front-rear direction of the vehicle body. The propeller shaft 50 is composed of, for example, two shaft members 51 and 52 connected in the front-rear direction of the vehicle body via a universal joint 55. The rear end of the propeller shaft 50 is connected to the front end of the input shaft 61 of the coupling 60 via a universal joint 59.

The transfer device 40 is arranged on one of the front wheel drive shafts 22 (for example, on the right side of the vehicle body). The transfer device 40 is connected to the differential case 12 of the front wheel differential device 10 on the input side thereof, and is connected to the front end portion of the propeller shaft 50 via a universal joint 49 on the output side.

As a result, in the state where the coupling 60 is fastened, a part of the power of the engine 6 transmitted to the differential case 12 of the front wheel differential device 10 via the transmission or the like is transferred to the rear wheel 4 side by the transfer device 40. It is designed to be taken out. The configuration of the transfer device 40 will be described later.

In the state where the coupling 60 is fastened, the power of the engine 6 taken out by the transfer device 40 is the propeller shaft 50, the coupling 60, the rear wheel differential device 70 and the rear wheel drive shaft 31, from the transfer device 40. It is transmitted to the rear wheel 4 via 32. The power input to the differential case 72 of the rear wheel differential device 70 is transmitted to the left and right rear wheels 4 via the left and right rear wheel drive shafts 31 and 32 so as to have a rotation difference according to the traveling situation. NS.

The configuration of the transfer device 40 will be described with reference to the cross-sectional view of FIG.

The transfer device 40 is provided on an input shaft 41 extending in the vehicle body width direction, an output shaft 42 extending in the vehicle body front-rear direction, a transfer drive gear (hereinafter referred to as “drive gear”) 43 provided on the input shaft 41, and an output shaft 42. A transfer-driven gear (hereinafter referred to as "driven gear") 44 that is provided and meshes with the drive gear 43, and a transfer case 48 that houses a part of the input shaft 41, a part of the output shaft 42, the drive gear 43, the driven gear 44, and the like. I have.

The input shaft 41 and the drive gear 43 are connected to each other via the power transmission shaft 46. The input shaft 41 and the power transmission shaft 46 are tubular members arranged on the axis of the front wheel drive shaft 22.

The input shaft 41 is fitted to the outside of one of the front wheel drive shafts 22 with a gap. The end (not shown) of one side (left side of FIG. 2) of the input shaft 41 is connected to the differential case 12 (see FIG. 1) of the front wheel differential device 10 by, for example, spline fitting. The input shaft 41 rotates together with the differential case 12.

The input shaft 41 is integrally formed with the inner cylinder portion 82 of the damper, which will be described later. At the end of the input shaft 41 (inner cylinder portion 82) on the other side (right side in FIG. 2), an annular wall portion 82a projecting outward in the radial direction and an annular wall portion 82a projecting axially from the wall portion 82a toward the anti-def case 12 side. The cylindrical protrusion 82b is integrally provided.

The power transmission shaft 46 projects from the input shaft 41 toward the anti-def case 12 side (right side in FIG. 2) and extends. The power transmission shaft 46 has a diameter larger than that of the outer cylinder portion 84 of the damper 80, which will be described later, and has a large diameter portion 46a arranged outside the outer cylinder portion 84. The power transmission shaft 46 includes an annular vertical wall portion 46b protruding inward in the radial direction from the end of the large diameter portion 46a on the differential case 12 side (left side in FIG. 2), and an input shaft from the vertical wall portion 46b to the differential case 12 side. A cylindrical small-diameter portion 46c having a diameter smaller than that of the large-diameter portion 46a extending in the axial direction along the outer peripheral portion of 41 is provided.

The power transmission shaft 46 is spline-fitted to the outside of the input shaft 41 (more specifically, the cylindrical protrusion 82b of the inner cylinder portion 82) at the portion of the large diameter portion 46a on the anti-def case 12 side (right side in FIG. 2). Has been done. The power transmission shaft 46 is rotatably supported by the transfer case 48 via a pair of bearings 101 and 102 arranged at intervals in the vehicle body width direction. A part of the spline fitting portion between the input shaft 41 (inner cylinder portion 82) and the power transmission shaft 46 overlaps with the bearing 102 in the axial direction.

The drive gear 43 is provided on the outer periphery of the power transmission shaft 46. The drive gear 43 is spline-fitted on the outside of the power transmission shaft 46 so that it rotates together with the input shaft 41.

The input shaft 41 is provided with a so-called compression type damper 80 that attenuates torsional vibration by compressing and deforming an elastic member in the circumferential direction. The damper 80 is provided on the power transmission path from the input shaft 41 connected to the front wheel drive unit 20 of the transfer device 40 to the drive gear 43. In other words, the damper arrangement space S is formed between the input shaft 41 and the power transmission shaft 46. As a result, the torsional rigidity of the rear wheel drive unit 30 is reduced, and the natural frequency related to the torsional vibration of the rear wheel drive unit 30 is a frequency that does not resonate with the torque fluctuation that may occur in the normal range of the engine speed. It is shifted to the area. The specific configuration of the damper 80 will be described later.

The output shaft 42 is a solid shaft member arranged so as to extend in the front-rear direction of the vehicle body. The axis of the output shaft 42 is arranged closer to the differential case 12 than the drive gear 43 in the vehicle body width direction. Further, the axis of the output shaft 42 is offset below the axis of the front wheel drive shaft 22 in the vertical direction of the vehicle body.

The output shaft 42 is rotatably supported by the transfer case 48 via a pair of front and rear bearings 103 and 104 arranged at intervals in the front-rear direction of the vehicle body. A cylindrical distance piece 105 fitted to the outside of the output shaft 42 is interposed between the inner races of the pair of bearings 103 and 104.

A connecting member 106 is fitted to the outside of the vehicle body rear side portion of the output shaft 42 with respect to the vehicle body rear side bearing 104. A universal joint 49 (see FIG. 1) is fixed to the rear end of the connecting member 106. As a result, the output shaft 42 is connected to the front end portion of the propeller shaft 50 (see FIG. 1) via the connecting member 106 and the universal joint 49.

A nut 107 is screwed into the rear end of the output shaft 42. By tightening the nut 107, the inner race, distance piece 105, and connecting member 106 of the pair of bearings 103, 104 sandwiched between the driven gear 44 and the nut 107 on the output shaft 42 are positioned in the axial direction. Is fixed to the output shaft 42.

When the nut 107 is tightened during assembly, the distance piece 105 is plastically deformed through an elastic deformation state, and the preload of the bearings 103 and 104 is adjusted while the distance piece 105 is plastically deformed.

The driven gear 44 is provided integrally with the front end of the output shaft 42, for example. The driven gear 44 is cantilevered from the rear side of the vehicle body via the pair of bearings 103 and 104, and the support rigidity of the driven gear 44 is precisely controlled by the preload of the bearings 103 and 104 as described above. It is enhanced by being done.

The drive gear 43 and the driven gear 44 are bevel gears such as a hypoid gear. The teeth of the drive gear 43 are arranged so as to face the differential case 12 side in the vehicle body width direction, and the teeth of the driven gear 44 are arranged so as to face the front side of the vehicle body. The driven gear 44 has a smaller diameter than the drive gear 43. As a result, the rotation of the input shaft 41 of the transfer device 40 is accelerated and transmitted to the output shaft 42 and the propeller shaft 50 (see FIG. 1).

Lubricating oil is sealed in the transfer case 48. As the oil, an oil containing a component capable of reliably preventing seizure at the meshing portion between the drive gear 43 and the driven gear 44 is used.

Between the outer peripheral surface of the power transmission shaft 46 of the input shaft 41 and the inner peripheral surface of the transfer case 48, between the inner peripheral surface of the power transmission shaft 46 and the outer peripheral surface of the front wheel drive shaft 22, the front wheel drive shaft 22 Between the outer peripheral surface and the inner peripheral surface of the transfer case 48, and between the outer peripheral surface of the connecting member 106 and the inner peripheral surface of the transfer case 48, oiltightness is allowed while allowing relative rotation between the two members, respectively. Sealing members 111, 112, 113, 114, 115 that ensure property or airtightness are interposed.

The configuration of the damper 80 will be described with reference to FIG.

The damper 80 has a double pipe structure including an inner cylinder portion 82 formed integrally with the input shaft 41 and an outer cylinder portion 84 as described above. The inner cylinder portion 82 and the outer cylinder portion 84 are made of, for example, a metal tubular member, and are arranged on the center of the front wheel drive shaft 22. The inner cylinder portion 82 (input shaft 41) is fitted to the outside of the front wheel drive shaft 22 with a gap. The inner cylinder portion 82 is arranged adjacent to the anti-def case 12 side (right side in FIG. 2) of the vertical wall portion 46b of the power transmission shaft 46 in the axial direction. The outer cylinder portion 84 has a diameter larger than that of the inner cylinder portion 82, and is arranged outside the inner cylinder portion 82 and inside the power transmission shaft 46 in the radial direction.

As described above, the inner cylinder portion 82 is integrally formed with the input shaft 41. Therefore, it is not necessary to provide a spline fitting portion for connecting the input shaft 41 and the inner cylinder portion 82. The outer cylinder portion 84 is spline-fitted inside the power transmission shaft 46 at a position adjacent to the spline fitting portion (connecting portion) between the power transmission shaft 46 and the input shaft 41 (inner cylinder portion 82). There is. The area occupied in the axial direction of the press-fitting portion spline fitting portion between the outer cylinder portion 84 and the power transmission shaft 46 overlaps with the drive gear 43.

The damper 80 further includes an elastic body layer 90 arranged between the inner cylinder portion 82 and the outer cylinder portion 84. The elastic body layer 90 is composed of, for example, a plurality of elastic members 93 (see FIG. 4) made of rubber. A more specific configuration of the elastic layer 90 will be described later.

The spline fitting portion between the outer cylinder portion 84 of the damper 80 and the power transmission shaft 46, and the spline fitting portion between the input shaft 41 (cylindrical protrusion 82b of the inner cylinder portion 82) and the power transmission shaft 46 are differential cases. They are arranged adjacent to each other in this order from the 12 side (left side in FIG. 2) in the axial direction. For these spline fittings, a common internal tooth 46d (see FIGS. 3 and 4) provided on the inner peripheral surface of the power transmission shaft 46 is used.

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2 when the spline fitting portion between the input shaft 41 (cylindrical protrusion 82b of the inner cylinder portion 82) and the power transmission shaft 46 is viewed from the axial direction. Is a sectional view taken along line IV-IV of FIG. 2 as seen from the axial direction of a spline fitting portion between the outer cylinder portion 84 of the damper 80 and the power transmission shaft 46. Further, in FIGS. 3 and 4, the front wheel drive shaft 22 is shown by a two-dot chain line.

As shown in FIG. 3, in the spline fitting portion between the input shaft 41 and the power transmission shaft 46, each outer tooth 82c of the input shaft 41 is centered in the circumferential direction between a pair of adjacent internal teeth 46d of the power transmission shaft 46. The portions are arranged so as to be relatively movable within a predetermined range L in the circumferential direction. As a result, the input shaft 41 and the power transmission shaft 46 are allowed to rotate relative to each other within a predetermined angle range α.

On the other hand, in the spline fitting portion between the power transmission shaft 46 and the outer cylinder portion 84 of the damper 80 shown in FIG. 4, each outer tooth 84a of the outer cylinder portion 84 is a pair of adjacent inner wheels of the power transmission shaft 46. It is arranged between the teeth 46d with almost no gap. As a result, in the spline fitting portion between the power transmission shaft 46 and the outer cylinder portion 84, the outer teeth 84a and the inner teeth 46d in the circumferential direction are compared with the spline fitting portion between the input shaft 41 and the power transmission shaft 46. Relative movement between them, and thus relative rotation between the power transmission shaft 46 and the outer cylinder portion 84, is severely restricted.

As described above, the backlash (play in the circumferential direction) generated between the outer teeth 82c and the inner teeth 46d at the spline fitting portion (see FIG. 3) between the input shaft 41 and the power transmission shaft 46 is the power transmission shaft. It is configured to be larger than the backlash (play in the circumferential direction) (see FIG. 4) that occurs between the outer teeth 84a and the inner teeth 46d in the spline fitting portion between the 46 and the outer cylinder portion 84 of the damper 80. ing.

When a torque less than a predetermined value is transmitted between the input shaft 41 of the input shaft 41 and the power transmission shaft 46, the input shaft 41 and the power transmission shaft 46 are relative to each other in the circumferential direction according to the magnitude of the input torque. Displace. At this time, the engagement between the external teeth and the internal teeth at each spline fitting portion of the input shaft 41 is performed before the spline fitting portion (see FIG. 3) between the input shaft 41 and the power transmission shaft 46. This is done at the spline fitting portion (see FIG. 4) between the 46 and the outer cylinder portion 84 of the damper 80.

Therefore, when the torque transmitted between the input shaft 41 and the power transmission shaft 46 is less than a predetermined value, the torque transmission path is the spline fitting portion between the input shaft 41 and the power transmission shaft 46 (FIG. 3). A route via the input shaft 41 (inner cylinder portion 82), the damper 80, and the spline fitting portion (see FIG. 2) between the outer cylinder portion 84 of the damper 80 and the power transmission shaft 46 without passing through the input shaft 41 (inner cylinder portion 82). become.

That is, when the torque input to the transfer device 40 from the engine 6 side is less than a predetermined value, for example, in a front wheel drive state or a four-wheel drive state in which the torque distributed to the rear wheel 4 side is relatively low, the transfer is performed. In the device 40, torque is transmitted via a path via the damper 80.

On the other hand, when the torque transmitted between the input shaft 41 and the power transmission shaft 46 is equal to or higher than a predetermined value, the spline fitting portion between the input shaft 41 (inner cylinder portion 82) and the power transmission shaft 46 (see FIG. 3). ) Is transmitted via torque.

That is, when the torque input to the transfer device 40 from the engine 6 side is equal to or higher than a predetermined value, for example, in a four-wheel drive state in which the fastening force is relatively strong, the transfer device 40 uses the input shaft 41 (inner cylinder portion 82). In addition to the path via the damper 80 and the spline fitting portion between the outer cylinder portion 84 of the damper 80 and the power transmission shaft 46, torque transmission is performed by a path that does not pass through the damper 80.

When torque is transmitted between the input shaft 41 (inner cylinder portion 82) and the power transmission shaft 46, the relative displacement between the two shaft members 45 and 46 in the circumferential direction is the spline between the two shaft members 45 and 46. The amount is restricted to a predetermined amount or less by the interference between the outer teeth 82c and the inner teeth 46d at the fitting portion (see FIG. 3). As a result, the relative displacement amount in the circumferential direction is also a predetermined amount between the inner cylinder portion 82 of the damper 80 spline-fitted to the input shaft 41 and the outer cylinder portion 84 spline-fitted to the power transmission shaft 46. It will be regulated as follows.

In this way, the spline fitting portion (see FIG. 3) between the input shaft 41 and the power transmission shaft 46 regulates the relative displacement amount in the circumferential direction between the inner cylinder portion 82 and the outer cylinder portion 84 of the damper 80. It acts as a stopper mechanism, and the action of the stopper mechanism can prevent an excessive load from being applied to the elastic body layer 90 of the damper 80.

As shown in FIG. 4, a plurality of outward protrusions 83 are provided on the outer peripheral surface of the inner cylinder portion 82 of the damper 80 at intervals in the circumferential direction. The plurality of outward protrusions 83 are arranged at equal intervals in the circumferential direction. The radial outer ends of the outer protrusions 83 are arranged close to and facing the inner peripheral surface of the outer cylinder 84.

A plurality of inward protrusions 85 are provided on the inner peripheral surface of the outer cylinder portion 84 at intervals in the circumferential direction. The plurality of inward protrusions 85 are arranged at equal intervals in the circumferential direction. The radial inner end of each inward protrusion 85 is arranged close to and facing the outer peripheral surface of the inner cylinder 82. Each inward protrusion 85 is arranged offset in the circumferential direction to one side (front side in the clockwise direction of FIG. 4) with respect to the central portion between the pair of adjacent outer protrusions 83.

The elastic body layer 90 has an outer protrusion 83 and an inner protrusion 85 when the inner cylinder portion 82 is displaced to the downstream side relative to the outer cylinder portion 84 in the rotation direction F1 when the vehicle 1 travels forward. When the first elastic portion 91 that is compression-deformed between the two and the inner cylinder portion 82 is displaced upstream with respect to the outer cylinder portion 84 in the same rotation direction F1, the outer protrusion portion 83 and the inner cylinder portion 83 are inward. It has a second elastic portion 92 that is compressively deformed with the protrusion 85.

The first elastic portion 91 is composed of a plurality of first elastic members 93 arranged adjacent to the downstream side of the outer protrusion 83 in the rotation direction F1 during forward traveling. Each first elastic member 93 is a rod-shaped member extending in the axial direction of the damper 80. The first elastic member 93 is made of an elastic material such as rubber.

The second elastic portion 92 is composed of a plurality of second elastic members 94 arranged adjacent to the downstream side of the inward protrusion 85 in the rotation direction F1 during forward traveling. Each second elastic member 94 is a rod-shaped member extending in the axial direction of the damper 80. The second elastic member 94 is made of an elastic material such as rubber.

Each section between the outer protrusion 83 and the inner protrusion 85 adjacent to each other in the circumferential direction has one elastic member of either the first elastic member 93 or the second elastic member 94, respectively. Have been placed. The total number of the first elastic members 93 and the total number of the second elastic members 94 are the same. The first elastic member 93 and the second elastic member 94 are alternately arranged in the circumferential direction via the outer protrusion 83 or the inner protrusion 85.

In a state where no torque is applied to the damper 80, each of the first elastic members 93 and each second elastic member 94 is between the outer protrusion 83 and the inner protrusion 85 in a state of being slightly compressed in the circumferential direction. It is placed sandwiched between.

In this embodiment, all the first elastic members 93 are made of the same material and have the same shape and the same size. That is, all the first elastic members 93 have the same rigidity with respect to the load in the rotation direction F1. Further, the second elastic member 94 is made of the same material and has the same shape and the same size. That is, all the second elastic members 94 have the same rigidity with respect to the load in the rotation direction F1.

In a two-wheel drive state in which suppression of rattling noise in the power transmission system on the rear wheel 4 side (secondary drive wheel side) is an issue, the transfer device 40 transmits only torque equal to or less than a predetermined value. The torque transmission path in the above is usually a path via the damper 80.

In this case, when the torque transmission direction is from the engine 6 side to the rear wheel 4 side, in the damper 80, the inner cylinder portion 82 is on the downstream side of the rotation direction F1 during forward traveling with respect to the outer cylinder portion 84. Relative displacement. As a result, each of the first elastic members 93 sandwiched between the inner protrusion 85 adjacent to the downstream side in the rotation direction F1 and the outer protrusion 83 adjacent to the upstream side is compression-deformed.

In the present embodiment, the second elastic member 94 has a lower rigidity than the first elastic member 93, but the present invention is not limited to this, and the second elastic member 94 makes the first elastic member 94. The amount of movement (rotation amount) of the inner cylinder portion 82 when the compressed state of the elastic member 93 is released may be regulated.

As described above, according to the power transmission device of the present embodiment, since the damper 80 is provided between the input shaft 41 of the transfer device 40 and the power transmission shaft 46, the torsional rigidity of the rear wheel drive unit 30 is reduced. Will be done. As a result, the natural frequency of the rear wheel drive unit 30 can be shifted to a vibration range that does not resonate with torque fluctuations that may occur in the normal range of the engine speed.

Since the input shaft 41 and the inner cylinder portion 82 of the damper 80 are integrally formed, it is possible to reduce the number of spline fitting portions for connecting the input shaft 41 and the inner cylinder portion 82. As a result, the man-hours for processing the spline are reduced, and since it is not necessary to provide a connecting portion or the like between the input shaft 41 and the inner cylinder portion 82, the power transmission shaft 46 for providing the connecting portion Axial dimensions can be shortened.

Since the spline fitting portion between the input shaft 41 and the power transmission shaft 46 is provided in the large diameter portion 46a of the power transmission shaft 46, as compared with the case where the spline fitting portion is provided in the small diameter portion 46c, for example. , It is easy to secure the strength corresponding to the surface pressure required for the spline fitting part. Therefore, for example, it is not necessary to perform heat treatment such as charcoal burning to secure the strength corresponding to the surface pressure required for the spline fitting portion, or to extend the axial length of the spline fitting portion.

From the above, in the power transmission device of the vehicle provided with the main drive wheel and the sub drive wheel, it is possible to reduce the manufacturing process and the cost of the transfer device 40 while suppressing the rattling noise.

Since the outer cylinder portion 84 of the damper 80 and the power transmission shaft 46 are spline-fitted in the vicinity of the spline fitting portion of the power transmission shaft 46 and the input shaft 41 via the backlash, these spline fittings are performed. Departments can be centrally arranged.

Each internal tooth 46d of the power transmission shaft 46 in the spline fitting portion between the power transmission shaft 46 and the input shaft 41 and the spline fitting portion between the power transmission shaft 46 and the outer cylinder portion 84 of the damper 80 Since they have a common shape, each internal tooth 46d of the two spline fitting portions of the power transmission shaft 46 can be formed by one process.

Since the spline fitting portion between the input shaft 41 and the power transmission shaft 46 is provided in the large diameter portion 46a of the power transmission shaft 46, the shaft of the spline fitting portion is provided as compared with the case where it is provided in the small diameter portion 46c. It is easy to shorten the directional length, and it is easy to shorten the axial dimension of the transfer device. This means the front-wheel drive state of a so-called FF (front engine / front drive) -based four-wheel drive vehicle, or RR (rear engine / rear drive) -based four-wheel drive, which requires compactness in the vehicle body width direction. A more pronounced effect is obtained in the rear-wheel drive state of the vehicle.

Since the damper 80 is arranged so as to overlap the transfer drive gear 43 in the axial direction of the input shaft 41, the axial dimension of the transfer device 40 can be made compact.

The present invention is not limited to the illustrated embodiments, and various improvements and design changes can be made without departing from the gist of the present invention.

For example, in the present embodiment, the damper 80 has been described as a compression type damper, but the damper is not limited to this, and the damper has an inner cylinder portion, an outer cylinder portion, and a tubular shape interposed between them. A shear type damper that is equipped with an elastic member such as rubber and is shear-deformed so that the elastic member is twisted in the circumferential direction due to a relative displacement in the circumferential direction between the inner cylinder portion and the outer cylinder portion. May be used.

Further, for example, in the present embodiment, a so-called FF (front engine / front drive) -based four-wheel drive vehicle has been described, but the present invention is not limited to this, and a so-called FR (front engine / rear drive) -based four-wheel drive vehicle is described. It can be provided for wheel drive vehicles and so-called RR (rear engine / rear drive) based four-wheel drive vehicles.

As described above, according to the present invention, in the power transmission device of the vehicle provided with the main drive wheel and the sub drive wheel, it is possible to reduce the manufacturing process and the cost of the power extraction unit. It may be suitably used in the field of manufacturing wheel drive vehicles.

2 Front wheels (main drive wheels)
4 Rear wheels (secondary drive wheels)
6 Engine (drive source)
20 Main drive wheel drive unit 30 Sub drive wheel drive unit 40 Transfer device (power extraction unit)
41 Input shaft 43 Transfer drive gear 44 Transfer driven gear 46 Power transmission shaft 46a Large diameter part 46c Small diameter part 80 Damper 82 Inner cylinder 84 Outer cylinder 90 Elastic member S Damper arrangement space

Claims (5)

A main drive wheel drive unit for transmitting power from the drive source to the main drive wheels,
A power transmission device including an auxiliary drive wheel drive unit having a power extraction unit for extracting power transmitted to the auxiliary drive wheels from the main drive wheel drive unit.
The power take-out unit is
A transfer gear set including a transfer drive gear connected to the main drive wheel drive unit and a transfer-driven gear that meshes with the transfer drive gear and transmits power to the auxiliary drive wheels.
A damper provided on the power transmission path from the main drive wheel drive unit to the transfer drive gear, and an elastic member interposed between the inner cylinder portion, the outer cylinder portion, and both cylinder portions.
A power transmission shaft that supports the transfer drive gear and has a large-diameter portion arranged on the outer peripheral side of the outer cylinder portion and a small-diameter portion smaller than the large-diameter portion.
It has an input shaft that extends from the inner peripheral portion of the small diameter portion toward the large diameter portion and forms a damper arrangement space with the power transmission shaft.
The input shaft is formed integrally with the inner cylinder portion, and is characterized in that it extends outward in the radial direction and is connected to the large diameter portion of the power transmission shaft via a spline having backlash. Power transmission device. The power transmission according to claim 1, wherein the outer cylinder portion and the power transmission shaft are spline-fitted in the vicinity of the spline fitting portion between the power transmission shaft and the input shaft. Device. The internal teeth formed on the power transmission shaft of the spline fitting portion between the power transmission shaft and the input shaft and the spline fitting portion between the power transmission shaft and the outer cylinder portion of the damper are The power transmission device according to claim 1 or 2, wherein the power transmission device is formed of a common spline. The method according to any one of claims 1 to 3, wherein the main drive wheel is arranged on the power source side of the vehicle body, and the sub drive wheel is arranged on the reaction power source side of the vehicle body. Power transmission device. The power transmission device according to any one of claims 1 to 4, wherein the damper is arranged so as to overlap the transfer drive gear in the axial direction of the input shaft.

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