JP2906249B2 - Driving force transmission device for four-wheel drive vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force transmission device for a four-wheel drive vehicle, and more particularly, to a rear part of a four-wheel drive vehicle based on a front-wheel drive type internal combustion engine front vehicle. The present invention relates to a driving force transmission device for a four-wheel drive vehicle in which insufficient driving force transmission to wheels is improved.

[Conventional technology]

In recent years, in order to improve the running performance and safety not only on rough roads and on rough terrain, but also on all roads, such as on ordinary roads, the driving force of the internal combustion engine is transmitted to all axles and all wheels are transmitted. There are many types of four-wheel drive vehicles that drive.
Examples of such a driving force transmitting device for a four-wheel drive vehicle include those disclosed in Japanese Patent Application Laid-Open Nos. 60-1030 and 60-236839.

Japanese Unexamined Patent Publication No. 60-1030 discloses a wet clutch device provided radially inside a front final reduction gear that meshes with an output gear of a transmission and coaxial with the front final reduction gear. Thereby, the left and right deviation of the front differential mechanism can be prevented, the difference between the front left and right axle lengths can be reduced, so that the occurrence of so-called torque steer can be suppressed, and the rotational speed difference between the front and rear wheels can be reduced. The torque distribution of the driving force transmitted to the front wheels and the rear wheels can be changed while being absorbed.

Japanese Unexamined Patent Publication No. 60-236839 discloses a differential limiting mechanism provided coaxially with a front differential mechanism in a mount casing supporting gears of a driving force distribution mechanism. Since the limiting mechanism is interposed between the input side and the other output side of the front differential mechanism, a differential limiting torque is generated when the input side and the other output side of the front differential mechanism rotate relative to each other to drive. In addition to improving the performance, the differential limiting mechanism can be compactly assembled by utilizing the space in the mount casing.

[Problems to be solved by the invention]

By the way, the four-wheel drive vehicle is based on a so-called front-mounted internal-combustion engine front-wheel-drive vehicle in which the front wheels are driven by the driving force of an internal-combustion engine mounted on the front side. There is a four-wheel drive vehicle that drives the rear wheels by distributing the driving force of an internal combustion engine.

For example, as shown in FIGS. 7 to 10, in a four-wheel drive vehicle 202, a driving force of an internal combustion engine 204 mounted on the front is converted into a desired torque and rotation speed by a transmission 206 and taken out. The front right axle 212R and the front left axle 212 which are the front axle 212 from the front final deceleration mechanism 208 via the front differential mechanism 210
L, respectively, and drives the front right wheel 214R and the front left wheel 214L, which are the front wheels 214, respectively, and the driving force distributed by the driving force distribution mechanism 216 from the rear final reduction mechanism 220 by the propulsion shaft 218. Rear axle 22 via rear differential 222
The rear wheel axle 224R and the rear left axle 224L are transmitted to drive the rear right wheel 226R and the rear left wheel 226L, respectively.

The front wheel 214 and the rear wheel 22 of such a four-wheel drive vehicle 202
In some cases, a viscous coupling (a viscous coupling) 228 is provided in order to allow a differential with the motor 6 and to limit a differential exceeding a certain value. The viscous joint 228 is connected to, for example, the output shaft 230 of the driving force distribution mechanism 216 and the propulsion shaft 218 as shown in FIG.
And between the propulsion shaft 218 and the input shaft 232 of the rear final reduction mechanism 220 as shown in FIG. Etc.

However, in the four-wheel drive vehicle based on the front-wheel drive type internal combustion engine vehicle as described above, the load distribution of the front wheels and the rear wheels is biased toward the front wheels, so that the transmission to the rear wheels is performed. There is a problem of insufficient driving force. Such insufficient transmission of driving force to the rear wheels is particularly noticeable at the time of deceleration. For this reason, a four-wheel drive vehicle based on a front-wheel-drive internal-combustion-engine vehicle is a so-called front-wheel internal-combustion-engine rear-wheel drive system in which the rear wheels are driven by the driving force of an internal-combustion engine mounted in front. 4 based on vehicles
There is an inconvenience that the driving performance is disadvantageous compared to a wheel drive vehicle.

[Object of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a four-wheel drive vehicle based on a front internal combustion engine front wheel drive system capable of improving insufficient transmission of driving force to rear wheels, and to provide a front internal combustion engine rear wheel drive vehicle. An object of the present invention is to realize a driving force transmission device for a four-wheel drive vehicle that can exhibit the same running performance as a four-wheel drive vehicle based on the above and can improve running performance and safety.

[Means for solving the problem]

In order to achieve this object, the present invention transmits a driving force of an internal combustion engine mounted on the front to a front axle via a front differential mechanism to drive front wheels and distributes the driving force by a driving force distribution mechanism. In a four-wheel drive vehicle that transmits the driving force of the internal combustion engine to a rear axle via a rear differential mechanism and drives a rear wheel, the front differential mechanism is formed by a viscous joint and the rear differential mechanism is configured. The front differential housing of the front differential mechanism and the outer case of the viscous joint provided in the front differential housing are disengaged from each other by a differential gear train, so that a four-wheel drive state is achieved. A switching mechanism for switching to a wheel drive state is provided.

[Action]

According to the configuration of the present invention, since the front differential mechanism is constituted by the viscous coupling, the viscous coupling increases the driving force of the internal combustion engine when there is no rotational speed difference between the front wheels and the rear wheels. The front wheel is not driven because it does not transmit to the axle, and only when a difference in rotation speed between the front wheel and the rear wheel occurs due to sudden start or difference in μ of the road surface with respect to the front and rear wheels. The viscous coupling transmits the driving force of the internal combustion engine to drive the front wheels. On the other hand, by configuring the rear differential mechanism with a differential gear train, the driving force of the internal combustion engine is transmitted to the rear axle via the differential gear train of the rear differential mechanism, and the rear wheels are directly It will be driven.

A switching mechanism for switching between a four-wheel drive state and a two-wheel drive state by disengaging a front differential housing of the front differential mechanism and an outer case of a viscous joint provided in the front differential housing. Is provided, the vehicle can be easily switched from the four-wheel drive state to the two-wheel drive state at the time of vehicle inspection or maintenance,
Also, by providing a part of the mechanism in the viscous joint,
The number of parts can be reduced.

〔Example〕

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

1 to 6 show an embodiment of the present invention.
In FIG. 6, reference numeral 2 denotes a four-wheel drive vehicle. The four-wheel drive vehicle 2 transmits the driving force of the internal combustion engine 4 mounted on the front to the transmission 6.
The driving force is converted into a desired torque and rotation speed, and the driving force is extracted from the front final deceleration mechanism 8 via the front differential mechanism 10, and the front right axle 12R and the front left axle 12L, which are the front axle 12. To drive the front right wheel 14R and the front left wheel 14L, which are the front wheels 14, respectively. Also, the four-wheel drive vehicle 2 uses a propulsion shaft 18 to transmit a driving force of the internal combustion engine 4 distributed by a driving force distribution mechanism 16 from a rear final deceleration mechanism 20 via a rear differential mechanism 22 to a rear axle 24 on a rear right side. This is transmitted to the axle 24R and the rear left axle 24L, respectively, and drives the rear right wheel 26R and the rear left wheel 26L, which are the rear wheels 26, respectively.

More specifically, as shown in FIG. 1, the driving force of the internal combustion engine 4 mounted in front of the four-wheel drive vehicle 2 is input to the input shaft 30 of the transmission 6 via the clutch mechanism 28, and the transmission gear train The output torque is converted into a desired torque / rotational speed by the output shaft and extracted from the output shaft. The output end of the output shaft 34 includes a front final deceleration mechanism 8.
The front final reduction pinion 36 is fixedly provided. The driving force taken out of the output shaft 34 is reduced by the front final reduction gear 36 of the front final reduction mechanism 8 and the front final reduction gear 38 meshing with the front final reduction gear 36 and The front differential mechanism 10 transmits the front right axle 12R and the front left axle 12L to drive the front right wheel 14R and the front left wheel 14L, respectively.

A driven gear 42 fixed to one end of an input shaft 40 of the driving force distribution mechanism 16 meshes with the front final reduction gear 38 of the front final reduction mechanism 8. The driving force distributed and input to the input shaft 42 is applied to an input gear 44 fixed to the other end of the input shaft 42.
The output is output to the output shaft 48 by the output gear 46 meshing with. The driving force distributed by the driving force distribution mechanism 16 and output from the output shaft 48 is applied to the input shaft 50 of the rear final reduction mechanism 20 by the propulsion shaft 18.
Is transmitted to A rear final reduction gear 52 is fixed to the input shaft 50. The driving force transmitted to the input shaft 50 is reduced by the rear final reduction pinion 52 and the rear final reduction gear 54 meshing with the rear final reduction pinion 52, and transmitted to the rear differential mechanism 22. The transmission is transmitted to the rear right axle 24R and the rear left axle 24L by the differential mechanism 22, respectively, and drives the rear right wheel 26R and the rear left wheel 26L, respectively.

As described above, the driving force of the internal combustion engine 4 mounted on the front is transmitted to the front axle 12 via the front differential mechanism 10 to drive the front wheels 14 and is distributed by the driving force distribution mechanism 16. The driving force of the engine 4 is transmitted to the rear axle via the rear differential mechanism 22.
In the four-wheel drive vehicle 2 which transmits to the rear wheel 24 and drives the rear wheel 26, the front differential mechanism 10 is constituted by a viscous coupling (viscus coupling) 56 and the rear differential mechanism 22 as shown in FIGS. Are constituted by a differential gear train 58.

That is, the front differential mechanism 10 includes a front differential right housing 60R and a front differential left housing 60L, which are front differential housings 60, as shown in FIG. The front differential left housing 60L is fixed to the front final reduction gear 38 of the front final reduction mechanism 8, and is supported by the transmission first casing 64a by the front differential left bearing 62L. ing.
The front differential right housing 60R is fixed to the front final reduction gear wheel 38 via the front differential left housing 60L, and is connected to the transmission second casing 64b by the front differential right bearing 62R. It is provided pivotally. As shown in FIG. 3, a fan-shaped opening 66 is formed in the front right housing 60R at equal angular positions on the side and the outer periphery.

A viscous joint 56 is provided in the front differential right housing 60R and the front differential left housing 60L. The viscous joint 56 includes a right viscous joint 56R and a left viscous joint 56L. That is, the viscous joint 56 has an outer case 68 including a right outer case 68R, a central outer case 68C, and a left outer case 68L.

The right outer case 68R and the left outer case 68L of the outer case 68 are respectively a front right axle 12R and a front left axle.
Provided on one end of 12L so as to be rotatably supported. A front right wheel 14R and a front left wheel 14L are attached to the other ends of the front right axle 12R and the front left axle 12L, respectively. An outer case side spline 70 is formed and provided on the outer periphery of the right outer case 68R of the outer case 68.

On the right outer case 68R side of the inner circumference of the center outer case 68C of the outer case 68, the outer circumferences of a plurality of right outer plates 72R are fixed. Also, the central outer case 6
The outer periphery of a plurality of left outer plates 72L is fixed to the left outer case 68L side of the inner periphery of 8C. On the other hand, an inner periphery of a right inner plate 74R alternately arranged with the right outer plate 72R is fixedly provided on an outer periphery of one end side of the front right axle 12R. Further, an inner periphery of a left inner plate 74L alternately arranged with the left outer plate 72L is fixed to an outer periphery of one end of the front left axle 12L.

In the outer case 68, these right outer plate 72R and left outer plate 72L and right inner plate
The viscous fluid 76 is filled so that the 74R and the left inner plate 74L are immersed.

Thereby, the center outer case of the outer case 68
68C right outer case 68R side and right outer case 68R
And the right outer plate 72R and the right inner plate 74R
And the viscous fluid 76 constitute the right viscous joint 56R. Also, a central outer case of the outer case 68 is provided.
68C left outer case 68L side and left outer case 68L
And left outer plate 72L and left inner plate 74L
And the viscous fluid 76 constitute the left viscous joint 56L.

Further, a switching mechanism 78 is provided in the front differential mechanism 10. The switching mechanism 78 has a switching sleeve 80 as shown in FIGS. Inside the switching sleeve 80, an outer formed on the outer periphery of the right outer case 68R at a position corresponding to the fan-shaped opening 66 formed at an equiangular position on the side and outer periphery of the front right housing 60R. A sleeve-side spline 82 that engages with and disengages from the case-side spline 70 is formed. A sleeve groove 84 is formed on the outer periphery of the switching sleeve 80. A switching fork 86 is slidably engaged with the sleeve groove 84.

The switching fork 86 is fixed to one end of the switching shaft 88. The switching shaft 88 is provided so as to be slidable in the axial direction on a holding portion 90 provided on the transmission second casing 64b. On the other end side of the switching shaft 88, an engagement recess 92 is formed. The engagement recess 92 has an operating lever.
The engagement protrusion 96 provided on the rotation tip side of the 94 is engaged.
The rotation base end side of the operation lever 94 is fixed to one end side of the operation shaft 98. The operating shaft 98 has both ends protruding into and out of the transmission second casing 64b, respectively, and is rotatably supported by a support portion 100 provided on the transmission second casing 64b. The operating lever 94 is fixed to one end of the operating shaft 98 inside the transmission second casing 64b.
A switching lever 102 is attached to the other end of the operating shaft 98 outside the transmission second casing 64b. The switching lever 102 is operated manually or by a driving unit (not shown).

Thus, by operating the switching lever 102 in the direction of arrow A, the operating shaft 98 is rotated, the operating lever 94 is swung to slide the switching shaft 88 in the axial direction, and the switching fork 86 is moved in the solid line in FIG. When the sleeve is moved to the position shown in FIG. And is engaged with an outer case side spline 70 formed on the outer periphery of the right outer case 68R. Therefore, the front differential housing 60 and the outer case 68 rotate integrally, and are switched to the four-wheel drive state.

By operating the switching lever 102 in the direction of arrow B, the operating shaft 98 is rotated, and the operating lever 94 is swung to slide the switching shaft 88 in the axial direction.
2 is moved to the position shown by the broken line in FIG. 2 so that the sleeve-side spline 82 of the switching sleeve 80 moves forward from the fan-shaped opening 66 formed at the same angular position on the side and outer periphery of the front differential right housing 60R. It is pulled out of the differential right housing 60R and is separated from the outer case side spline 70 formed on the outer periphery of the right outer case 68R. For this reason, the front differential housing 60 and the outer case 68 are separately rotatable relative to each other, and are switched to the two-wheel drive state.

The rear differential mechanism 22 has a rear final reduction gear wheel 54 meshed with a rear final reduction gear 52 of the rear final reduction mechanism 20 fixedly mounted on a rear differential housing 104 of the rear differential mechanism 22. The rear differential housing 104 is supported by the rear axle housing 106 by a rear right differential bearing 108R and a rear left differential bearing 108L. A differential gear train 58 is provided in the rear differential housing 104. The differential gear train 58 includes a rear differential first small gear 112a and a rear differential second small gear 112b supported by a gear shaft 110, and a rear differential first small gear 112a and a rear differential second small gear 112b. The rear differential right gear 114R and the rear differential left gear 114L, which are the rear differential gear 114 meshing with the gear 112b, respectively.
It is composed of

Rear differential right large gear 114R and rear differential left large gear 114L
Are connected to one ends of the rear right axle 24R and the rear left axle 24L, respectively.
The rear right wheel 26R and the rear left wheel 26L are attached to the other end of the rear left axle 24L.

 Next, the operation will be described.

The driving force of the internal combustion engine 4 mounted in front of the four-wheel drive vehicle 2 is input to the input shaft 30 of the transmission 6 via the clutch mechanism 28, and is converted into a desired torque and rotation speed by the transmission gear train 32. From the output shaft 34. The driving force extracted from the output shaft 34 is the front final reduction gear of the front final reduction mechanism 8.
36 and the front final reduction large gear 38 meshing with the front final reduction pinion 36, the speed is reduced and transmitted to the front differential mechanism 10, and the front right differential 12R and the front right axle 12R are transmitted by the front differential mechanism 10. The driving force is transmitted to the left rear axle 12L, and drives the front right wheel 14R and the front left wheel 14L, respectively.

At this time, by operating the switching lever 102 of the switching mechanism 78 in the direction of arrow A, the operating shaft 98 is rotated, the operating lever 94 is swung to slide the switching shaft 88 in the axial direction, and the switching fork 86 When it is moved to the position shown by the solid line in FIG. 2, the sleeve side spline 82 of the switching sleeve 80 is engaged with the outer case side spline 70 formed on the outer periphery of the right outer case 68R. Therefore, the front differential housing 60 and the outer case 68 rotate integrally, and are switched to the four-wheel drive state.

In this four-wheel drive state, the front right wheel 14R, the front left wheel 14L, the rear left wheel 26R, and the rear left wheel 26L
When there is no rotational speed difference between the right viscous coupling 56R and the right outer plate 72R and the right inner plate 74R of the right viscous coupling 56R, there is no rotational speed difference, and the left viscous coupling 56L No rotational speed difference is generated between the left outer plate 72L and the left inner plate 74L, so that no driving force is transmitted to the front right axle 12R and the front left axle 12L, and the front right wheel 14R and the front left Wheel 14L is not driven.

However, sudden start and front right wheel 14R and front right wheel 1
4L and rear left wheel 26R and rear left wheel 26L.
When a rotational speed difference occurs between 4L and the rear right wheel 26R and the rear left wheel 26L, the front differential mechanism 10
56R right outer plate 72R and right inner plate 74
A rotational speed difference also occurs between R and a rotational speed difference also occurs between the left outer plate 72L and the left inner plate 74L of the left viscous joint 56L, so that the front right axle 12R and the front left axle 12L are driven. The force is transmitted, and the front right wheel 14R and the front left wheel 14L are driven.

On the other hand, the driving force of the internal combustion engine 2 is distributed from the front final reduction mechanism 8 by the driving force distribution mechanism 16 and transmitted to the propulsion shaft 18, and the differential gear train of the rear final reduction mechanism 20 to the rear differential mechanism 22
The transmission to the rear right axle 24R and the rear left axle 24L via 58 causes the rear right wheel 26R and the rear left wheel 2
6L will be driven directly.

Therefore, it is possible to improve insufficient transmission of driving force to the rear right wheel 26R and the rear left wheel 26L in the four-wheel drive vehicle 2 based on the front internal combustion engine front wheel drive type vehicle. Driving performance equivalent to that of a four-wheel drive vehicle based on a drive type vehicle can be exhibited, and travel performance and safety can be improved.

In addition, since the front differential mechanism 10 is constituted by the viscous coupling 56, the driving force transmission system of a so-called part-time four-wheel drive vehicle based on a conventional front-mounted internal combustion engine front wheel drive type vehicle is relatively small. By changing it, a so-called full-time four-wheel drive vehicle can be achieved, and unlike the conventional case where a viscous joint is provided at the propulsion shaft portion, no installation space for the viscous joint is required, and the installation space for the front differential mechanism is provided. The use of the device enables downsizing and cost reduction.

In addition, the viscous coupling 56, which is relatively heavy, is installed at the front differential mechanism 10 at a relatively low rotational speed, which is advantageous in terms of vibration. The joint can be cooled.

Further, by operating the switching lever 102 of the switching mechanism 78 in the direction of arrow B, the operating shaft 98 is rotated, the operating lever 94 is swung to slide the switching shaft 88 in the axial direction, and the switching fork 86 When moved to the position shown by the broken line in FIG. 2, the sleeve side spline 82 of the switching sleeve 80 is separated from the outer case side spline 70 formed on the outer periphery of the right outer case 68R. For this reason, the front differential housing 60 and the outer case 68 are separately rotatable relative to each other, and are switched to the two-wheel drive state.

As described above, by switching between the two-wheel drive state and the four-wheel drive state by the switching mechanism 78, the vehicle can be easily switched from the four-wheel drive state to the two-wheel drive state at the time of vehicle inspection or maintenance. By providing a part of the viscous joint, the number of parts can be reduced, which can contribute to cost reduction.

Further, if the switching mechanism 78 is configured to be operated by a drive unit, the switching mechanism 78 may be provided with an antilock brake system.
It is possible to achieve consistency with the four-wheel drive state when the anti-lock brake system is operated in a wheel drive vehicle, which is practically advantageous.

〔The invention's effect〕

As described above, according to the present invention, since the front differential mechanism is constituted by the viscous coupling, when there is no difference in rotation speed between the front wheel and the rear wheel, the viscous coupling drives the internal combustion engine. Is not transmitted to the front axle, the front wheels are not driven, and there is a rotational speed difference between the front wheels and the rear wheels due to sudden start, difference in μ of the road surface with respect to the front wheels and rear wheels, etc. Only the viscous coupling transmits the driving force of the internal combustion engine to drive the front wheels. On the other hand, by configuring the rear differential mechanism with a differential gear train, the driving force of the internal combustion engine is transmitted to the rear axle via the differential gear train of the rear differential mechanism, and the rear wheels are directly It will be driven.

For this reason, it is possible to improve the lack of transmission of driving force to the rear wheels in a four-wheel drive vehicle based on a front internal combustion engine front wheel drive type vehicle, and to improve the performance based on a front internal combustion engine rear wheel drive type vehicle. The running performance equivalent to that of a wheel drive vehicle can be exhibited, and the running performance and safety can be improved.

Further, since the front differential mechanism is constituted by a viscous joint, the driving force transmission system of a so-called part-time four-wheel drive vehicle based on a conventional front-wheel drive type internal combustion engine front-wheel drive vehicle can be changed with relatively few changes. It can be a so-called full-time four-wheel drive vehicle, and unlike the conventional case where a viscous joint is provided at the propulsion shaft part, no installation space for the viscous joint is required, and the installation space for the front differential mechanism is used. By doing so, compactness and cost reduction can be achieved.

In addition, a relatively heavy viscous joint is installed at the front differential mechanism where the rotational speed is relatively low, which is advantageous in terms of vibration.In addition, using a transaxle lubricating oil, a viscous joint is used. Can be cooled.

Further, the front differential housing of the front differential mechanism and the outer case of the viscous joint provided in the front differential housing are disengaged from each other to switch between the four-wheel drive state and the two-wheel drive state. By providing a mechanism, it is possible to easily switch from a four-wheel drive state to a two-wheel drive state during vehicle inspection and maintenance, etc. Also, by providing a part of the mechanism in a viscous joint, the number of parts can be reduced. This can contribute to cost reduction. Further, if the switching mechanism is operated by a driving unit, the switching mechanism is provided with an anti-lock brake system.
It is possible to achieve consistency with the four-wheel drive state when the anti-lock brake system is operated in a wheel drive vehicle, which is practically advantageous.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is a schematic explanatory view of a driving force transmission system, FIG. 2 is an enlarged explanatory view of a front differential mechanism portion, and FIG. FIG. 4 is a side view of the switching casing, FIG. 5 is a front view of the switching mechanism, and FIG. 6 is a schematic plan view of a driving force transmission system of a four-wheel drive vehicle. 7 to 10 show a conventional example, FIG. 7 is a schematic explanatory view of a transmission, a front differential mechanism and a driving force distribution mechanism, and FIGS. 8 to 10 are driving force transmission systems of a four-wheel drive vehicle, respectively. It is a schematic plan view of. In the figure, 2 is a four-wheel drive vehicle, 4 is an internal combustion engine, 6 is a transmission, 8 is a front final reduction gear, 10 is a front differential mechanism, 12R is a front right axle, 12L is a front left axle, 14R is the front right wheel, 14
L is the front left wheel, 16 is the driving force conversion mechanism, 18 is the propulsion shaft, 2
0 is a rear final reduction mechanism, 22 is a rear differential mechanism, 24R is a rear right axle, 24L is a rear left axle, 26R is a rear right wheel, 26L is a front right wheel, 56 is a viscous coupling, and 58 is a differential gear train And 78 are switching mechanisms.

Claims (1)

(57) [Claims] A driving force of an internal combustion engine mounted on a front side is transmitted to a front axle via a front differential mechanism to drive front wheels and is distributed by a driving force distribution mechanism. In a four-wheel drive vehicle that transmits rear wheels to a rear axle via a rear differential mechanism to drive rear wheels, the front differential mechanism is constituted by a viscous joint, and the rear differential mechanism is constituted by a differential gear train. Switching between a four-wheel drive state and a two-wheel drive state by disengaging the front differential housing of the front differential mechanism and the outer case of the viscous joint provided in the front differential housing. A driving force transmission device for a four-wheel drive vehicle, comprising a mechanism.