Motor vehicles – Having four wheels driven
Reexamination Certificate
2003-08-22
2004-10-19
Morris, Lesley D. (Department: 3611)
Motor vehicles
Having four wheels driven
C180S245000
Reexamination Certificate
active
06805217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a power transmission mechanism of a four-wheel drive vehicle, in which a power unit, including an engine and a transmission, is mounted between front wheels and rear wheels, in which a front end part of a power takeoff shaft of the transmission is connected to an input shaft of a differential gear for the front wheels through a propeller shaft, and in which a rear end part of the power takeoff shaft is connected to an input shaft of a final reduction gear for the rear wheels through a propeller shaft, and particularly relates to the power transmission mechanism which is suitable for the four-wheel drive vehicle having a four-wheel independent suspension system.
2. Description of the Related Art
As a power transmission mechanism employed for the aforementioned type of the four-wheel drive vehicle, the mechanism which is disclosed in Japanese Laid-Open Patent Publication No. 2001-301477, has been known. That is, as shown in
FIG. 6
, each of the right-and-left front wheels
101
and right-and-left rear wheels
102
, is suspended independently, by a suspension arm
103
which can swing up and down, and by a shock absorber (not shown). A power unit P, having an engine and a transmission, is mounted between the front wheel
101
and the rear wheel
102
.
Each of the differential gear
106
for the front wheels and final reduction gear
107
for the rear wheels, is mounted centrally with respect to a width of a body of the vehicle, and a power takeoff shaft
110
of the transmission is offset to be on the left side of a center line C of the width of the body of the vehicle with respect to a direction in which the vehicle runs forward, and extends in parallel with the centerline C. The front end part of the power takeoff shaft
110
is connected to an input shaft
114
of the differential gear
106
for the front wheels
101
through a propeller shaft
112
, which is arranged generally in parallel with the centerline C. On the other hand, the rear end part of the power takeoff shaft
110
is connected to an input shaft
118
of the final reduction gear
107
for the rear wheels
103
through a propeller shaft
115
, which tilts with respect to the centerline C.
The power unit P is mounted slightly rearwards relative to a center between the front wheel
101
and the rear wheel
102
. In the arrangement, the distance between the final reduction gear
107
and the rear end part of the power takeoff shaft
110
, is shorter than the distance between the differential gear
106
and the front end part of the power takeoff shaft
110
.
The input shaft
118
of the final reduction gear
107
, is arranged in parallel with the centerline C. The front end part of the propeller shaft
115
is coupled to the rear end part of the power takeoff shaft
110
through a universal joint
120
with a predetermined tilt angle therebetween. On the other hand, the rear end part of the propeller shaft
115
is coupled to the input shaft
118
of the final reduction gear
107
through a universal joint
121
with a predetermined tilt angle therebetween, too.
In the arrangement, the two universal joints
120
and
121
locating at the front and rear end parts of the propeller shaft
115
, are non-constant velocity universal joints, respectively. However, since both of the universal joints
120
and
121
are constructed symmetrical to each other, the changes in their rotational speeds during one rotation, are cancelled to each other. Therefore, the rotation is transmitted between the drive takeoff shaft
110
and the input shaft
118
, generally at an equal speed.
In the four-wheel drive vehicle having a four-wheel independent suspension, each of the differential gear
106
and the final reduction gear
107
, is mounted at a center with respect to the width of the vehicle, as aforementioned. With the arrangement, it is possible to make length of each of the suspension arms (A-shaped arms)
103
equal in a direction of right and left, and also possible to make each thereof longer. Namely, with the arrangement, the width of the vehicle is prevented from growing in size, and a suspension stroke thereof is secured to be long while suppressing any change in tread so that comfortable ride of the vehicle is realized.
However, in the power transmission mechanism, the drive shaft
110
and the input shaft
118
are connected by the propeller shaft
115
, tilted, via the two universal joints
120
,
121
, as explained above. That is, according to the arrangement, not only crossed axes angle between the propeller shaft
115
and the drive shaft
110
which are connected to each other via one
120
of the two universal joints and between the propeller shaft
115
and the input shaft
118
which are connected to each other via the other
121
of the two universal joints, become greater, but also the rotational speed of the power transmission mechanism is changed twice through the pair of universal joints
120
and
121
. Therefore, with the arrangement, it is difficult to reduce the loss of driving power which is transmitted to the rear wheels
102
. Also, the arrangement necessitates a counter-measure against short life of the universal joints
120
and
121
.
Also, according to the arrangement, the power unit P is mounted a bit backward (or rearward) with respect to a center between the front wheel
101
and the rear wheel
102
. Therefore, the distance between the power takeoff shaft
110
and the input shaft
118
, in which the propeller shaft
115
is mounted, becomes inevitably smaller. Therefore, the aforementioned crossed axes angle of the propeller shaft becomes larger.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a power transmission mechanism of a four-wheel drive vehicle, in which a loss of a driving power that is transmitted to rear wheels of the vehicle is reduced and a joint part (or coupling part) in the power transmission mechanism is simplified in construction while maintaining a good ride feeling and a compactness of the vehicle.
In accomplishing the above and other objects, there is provided a power transmission mechanism of a four-wheel drive vehicle, comprising: a power unit which has an engine and a transmission, in which the power unit is provided between front wheels and rear wheels; a power takeoff shaft of the transmission, in which the power takeoff shaft is provided generally in parallel and in offset with a centerline relative to a width of a body of the vehicle; a differential gear for the front wheels, in which the differential gear is provided centrally relative to the width of the body, and in which the differential gear has an input shaft provided in parallel with the centerline and provided coaxially with the power takeoff shaft; a front propeller shaft for connecting between a front part of the power takeoff shaft and a rear part of the input shaft of the differential gear; a final reduction gear for the rear wheels, in which the final reduction gear is provided centrally relative to the width of the body of the vehicle, in which the final reduction gear has an input shaft provided such that a front part of the input shaft tilts toward the power takeoff shaft with respect to the centerline; and a rear propeller shaft for connecting between a rear part of the power takeoff shaft and the front part of the input shaft of the final reduction gear, wherein the front propeller shaft is arranged so as to be coaxial with the power takeoff shaft and the input shaft of the differential gear, and wherein the rear propeller shaft is arranged so as to be coaxial with the input shaft of the final reduction gear.
According to the mechanism, since the front part of the input shaft of the final reduction gear tilts toward the power takeoff shaft with respect to the centerline of the vehicle, and since the propeller shaft for the rear wheels is generally coaxial with the input shaft of the final reduction gear, not only the downsizing, weight saving and simplificatio
Kinouchi Sosuke
Takagi Izumi
Kawasaki Jukogyo Kabushiki Kaisha
Morris Lesley D.
Wenderoth , Lind & Ponack, L.L.P.
Winner Tony
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