Planetary gear transmission systems or components – Differential planetary gearing – Bevel gear differential
Reexamination Certificate
1999-12-23
2001-10-09
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
Differential planetary gearing
Bevel gear differential
C475S221000
Reexamination Certificate
active
06299562
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a differential for a part-time 4-wheel drive vehicle, and more particularly, to a differential for a part-time 4-wheel drive vehicle that is equipped with a power cut-off device for preventing power from reversibly transmitting from the front wheels through a front propeller shaft to a power transfer case.
(b) Description of the Related Art
Generally, a part-time 4-wheel drive vehicle can be changed by the operator from a 4-wheel drive mode to a 2-wheel drive mode and vice versa.
FIG. 1
shows a drive train of a conventional part-time 4-wheel drive vehicle. The terms “front” and “rear” as used herein shall mean and refer to the respective forward and rearward directions of the vehicle body. Mounted on an output side of a transmission
52
is a power transfer case
53
that is used for selectively transmitting power to either both or one of the front and rear wheel sets
60
and
57
, according to a drive mode of the vehicle.
That is, the power transfer case
53
is connected to a rear differential
55
via a rear propeller shaft
54
to transmit power to a rear axle shaft
56
supporting the rear wheels
57
. The power transfer case
53
is further connected to a front differential
70
via a front propeller shaft
58
to selectively transmit power to a front axle shaft
59
supporting the front wheels
60
.
Accordingly, in 4-wheel drive mode, the power transfer case
52
transmits power to both front and rear wheel sets
60
and
57
, and in 2-wheel drive mode, to only the rear wheel set
57
.
However, in 2-wheel drive mode, power generated by the rotation of the front wheels is reversibly transmitted to the front propeller shaft
58
through the front axle shaft
59
, resulting in power loss and generation of noise.
To solve the above problems, a power cut-off apparatus such as a free wheel hub system or a center axle disconnecting system have been provided between the front axle shaft and the front wheels to cut-off the power transmitted from the front wheels to the front propeller shaft.
However, the above well-known prior power cut-off apparatuses have large, complicated structures, which increases manufacturing costs.
SUMMARY OF THE INVENTION
Accordingly, there is a need for a power cut-off apparatus for a part-time 4-wheel drive vehicle which is simple in structure while providing more improved performance, thereby reducing manufacturing costs.
To meet the above need, the present invention provides a differential for a part-time 4-wheel drive vehicle, the differential comprising a differential assembly disposed on a front axle shaft to allow front wheels to turn at different speeds when the vehicle is in a turn, an outer case for receiving power from a power transfer case via a front propeller shaft, the outer case being disposed around the front axle shaft while enclosing the differential assembly, and a clutch lever assembly disposed between the outer case and the differential assembly to selectively couple the outer case to the differential assembly, the clutch lever assembly being mounted on the outer case so as to operate in a coupling direction to the differential assembly by centrifugal force generated when the outer case is rotated by power transmitted from the power transfer case.
The clutch lever assembly comprises at least one lever pivotally mounted on the outer case, the lever being provided near a first end with a coupling projection which is engaged with a recess formed on the differential assembly by centrifugal force generated when the outer case is rotated by power transmitted from the power transfer case, and a return spring for biasing the lever such that the coupling projection is maintained in a disengaged state from the recess of the differential assembly when power is not transmitted from the power transfer case to the outer case.
The lever is provided at a second end with a mass for enhancing pivotal movement of the lever by centrifugal force.
The differential may further comprise an electromagnetic assembly provided in the vicinity of the clutch lever assembly to forcedly disengage the clutch lever assembly from the differential case when the power transmission from the power transfer case is disconnected.
According to another aspect of the present invention, a power cut-off apparatus associated with a differential used in a part-time 4-wheel drive vehicle, the power cut-off apparatus comprises an outer case for receiving power from a power transfer case via a front propeller shaft, the outer case being disposed around an axle shaft while enclosing the differential, and a clutch lever assembly disposed between the outer case and the differential to selectively couple the outer case to the differential, the clutch lever assembly being mounted on the outer case so as to operate in a coupling direction to the differential by centrifugal force generated when the outer case is rotated by power transmitted from the power transfer case.
The clutch lever assembly comprises at least one lever pivotally mounted on the outer case, the lever being provided at a first end with a coupling projection which is engaged with a recess formed on the differential by centrifugal force generated when the outer case is rotated by power transmitted from the power transfer case, and a return spring for biasing the lever such that the coupling projection is maintained in a disengaged state from the recess of the differential when power is not transmitted from the power transfer case to the outer case.
REFERENCES:
patent: 3461746 (1969-08-01), Schwerdhofer
patent: 3517573 (1970-06-01), Roper
patent: 3985045 (1976-10-01), Shilling et al.
patent: 4389909 (1983-06-01), Goscenski, Jr.
patent: 4420993 (1983-12-01), Woodcock
patent: 4750382 (1988-06-01), Marc
patent: 5057062 (1991-10-01), Yamasaki et al.
patent: 5890989 (1999-04-01), Yamazaki et al.
patent: 5902206 (1999-05-01), Oda et al.
patent: 5989147 (1999-11-01), Forrest et al.
patent: 6015361 (2000-01-01), Yamazaki et al.
patent: 403199741 (1991-08-01), None
Birch & Stewart Kolasch & Birch, LLP
Hyundai Motor Company
Marmor Charles A
Pang Roger
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