Motor vehicles – Having four wheels driven – With differential means for driving two wheel sets at...
Reexamination Certificate
1997-12-03
2003-02-25
Olszewski, Robert P. (Department: 3627)
Motor vehicles
Having four wheels driven
With differential means for driving two wheel sets at...
Reexamination Certificate
active
06523633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a power train, and particularly, it relates to a power train for four-wheel drive vehicles.
2. Description of Relevant Art
There has been disclosed a four-wheel drive vehicle power train (hereafter “first conventional power train”) in Japanese Patent Application Laid-Open Publication No. 3-224829, another four-wheel drive vehicle power train (hereafter “second conventional power train”) in U.S. Pat. No. 5,188,574, and still another four-wheel drive vehicle power train (hereafter “third conventional power train”) in U.S. Pat. No. 4,700,800.
The first conventional power train has a transmission and a power transfer device illustrated in
FIG. 1
, where they are designated by reference characters
403
and
401
, respectively. The power transfer device
401
includes a front drive train
409
+
411
+
413
and a rear transfer train
415
. The front drive train includes a planetary type final reduction gear
409
arranged coaxial to a transversely extending output shaft
405
of the transmission
403
, a planetary type center differential gear
411
and a front differential gear
413
.
Drive torque from the transmission
403
is supplied from the output shaft
405
, via the final reduction gear
409
, to the center differential gear
411
, where it is shared to be distributed on the one hand through the front differential gear
413
to left and right front axles
407
, and on the other hand through the rear transfer train
415
to rear axles. The left front axle
407
extends through the transmission output shaft
405
.
The second conventional power train has a transmission and a power transfer device illustrated in
FIG. 2
, where they are designated by reference characters
503
and
501
, respectively. The power transfer device
501
includes a drive train
509
+
511
+
513
and a transfer train
515
. The drive train includes a final reduction gear
509
arranged parallel to an output shaft
505
of the transmission
503
, a planetary type center differential gear
511
and a bevel differential gear
513
.
Drive torque from the transmission
503
is supplied from the output shaft
505
, via the final reduction gear
509
, to the center differential gear
511
, where it is shared to be distributed on the one hand through the differential gear
513
to a pair of left and right axles
507
, and on the other hand through the transfer train
515
to another pair of axles. The right axle
507
extends through the transmission output shaft
505
.
The third conventional power train is illustrated in FIG.
3
and has a transmission
603
and a power transfer device
601
. This power transfer device
601
includes a front drive train
611
+
613
and a rear transfer train
609
. The front drive train includes a planetary type center differential gear
611
and a front differential gear
613
.
Drive torque from the transmission
603
is supplied from the output shaft
605
on the one hand directly to the rear transfer train
609
, and on the other hand via the center differential gear
611
to the front differential gear
613
, where it is shared to be distributed to left and right front axles
607
. The left axle
607
extends through the transmission output shaft
605
.
In the conventional four-wheel drive vehicle power trains described, their power transfer devices
401
,
501
,
601
each respectively include a drive train having a center differential gear
411
,
511
,
611
supplying drive torque to a differential gear
413
,
513
,
613
, where it is differentially distributed to an associated pair of left and right axles
407
,
507
,
607
. Therefore; in modification for application to a two-wheel drive vehicle, each power train needs a significantly wide re-design covering most of principal components such as differential gears and housings associated with torque transmission lines, as their commonality is low.
As a result, four-wheel drive vehicles need dedicated components therefor with increase in size and weight.
Moreover, the first and second conventional power trains have their drive trains elongated along associated axles
407
,
507
with undesirable effects on a suspension stroke.
SUMMARY OF THE INVENTION
The present invention has been achieved with such points in view.
It therefore is an object of the present invention to provide a power train with an increased commonality between a two-wheel drive vehicle and a four-wheel drive vehicle, permitting a down-scaled, light-weighted design.
To achieve the object, a first aspect of the present invention provides a power train for a vehicle with an engine and a total of four drive wheels, the power train comprising a first power train for driving a first pair of drive wheels, the first power train comprising a transmission connected to the engine, and a first drive train comprising a first final reduction gear connected to the transmission, and a first differential gear connected between the first final reduction gear and the first pair of drive wheels, and a second power train for driving a second pair of drive wheels, the second power train comprising a power transfer train branched from the first drive train between the first final reduction gear and the first differential gear, and a second drive train connected to the second pair of drive wheels.
According to the first aspect, a first drive train for a four-wheel drive vehicle is employable for a two-wheel drive vehicle and has an increased commonality therebetween.
According to a second aspect of the invention, the first final reduction gear is connected to an output shaft of the transmission, the first differential gear has an input element thereof driven by the final reduction gear and an output element thereof driving an axle of one of the first pair of drive wheels, and the output shaft and the input element have rotation axes thereof aligned to the axle.
According to the second aspect, a first drive train for a four-wheel drive vehicle may have an input element eliminated therefrom, permitting a common use to a two-wheel drive vehicle with a flexibility in design to have an increased transverse axle length outside a first power train Further, a reverse application to the four-wheel drive vehicle can be achieved without an undesirable increase in transverse size or weight.
According to a third aspect of the invention, the power train further comprises a branching element formed on the input element for branching the power transfer train from the first drive train.
According to the third aspect, an ensured branching is allowed with a simplified supporting structure.
According to a fourth aspect of the invention, the input element comprises an integral part of a differential casing member of the first differential gear.
According to the fourth aspect, a first differential gear as well as a branching element has a simplified supporting structure, permitting an increased commonality of a differential casing member and a reduced cost.
According to a fifth aspect of the invention, the power transfer train includes a drive transfer mechanism connected to the input element for transferring drive torque shared therefrom in a first direction crossing the axle.
According to the fifth aspect, a first drive train for a four-wheel drive vehicle may be employed, as it is, for a two-wheel drive vehicle.
According to a sixth aspect of the invention, the drive transfer mechanism comprises a chain transmission mechanism.
According to the sixth aspect, a drive transfer mechanism has an increased flexibility in spatial arrangement with relaxed criteria for connection accuracy. Further, a second power train may stand free of noises and vibrations from a first power train.
According to a seventh aspect of the invention, the power transfer train further includes a transfer path displacing mechanism for displacing a transfer path of the drive torque in a second direction crossing the first direction.
According to the seventh aspect, a power transfer train permits a drive c
Ishikawa Yasuhiko
Tanaka Hiroyuki
Teraoka Masao
Fischer Andrew J.
Morrison & Foerster / LLP
Olszewski Robert P.
Tochigi Fuji Sangyo Kabushiki Kaisha
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