Planetary gear transmission systems or components – Differential planetary gearing – Bevel gear differential
Reexamination Certificate
2003-02-25
2004-06-29
Rodriguez, Saul (Department: 3681)
Planetary gear transmission systems or components
Differential planetary gearing
Bevel gear differential
C475S237000, C192S035000, C192S044000, C192S050000
Reexamination Certificate
active
06755763
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention is related to a two way over-running clutch, preferably for use in automotive differential or transfer case applications. More specifically, the present invention relates to a two-way over-running clutch assembly of a roller/ramp variety which can be controlled for selectively locking up an automotive differential assembly or transfer case and a method of controlling the engagement of the over-running clutch.
BACKGROUND OF THE INVENTION
Differential assemblies are used in motor vehicles to allow the wheels to turn at different rotational speeds while still providing power to the wheels. Various types of differential assemblies are used in motor vehicles to redirect the transfer of power to the driving axles.
In a standard open differential, as a vehicle turns, power continues to be provided through pinion and ring gears to the differential housing. As the inner and outer wheels trace circles of different radii, side gears attached to axle shafts are allowed to turn at different speeds by the motion of intermediate spider gears. As long as traction is maintained between the drive wheels and the road surface, the power is properly distributed to the wheels through the differential assembly. However, when traction is reduced or lost altogether at one or both wheels, a standard open differential assembly will allow one wheel to spin uselessly, providing little tractive power to the wheels. For instance, if one tire is on ice or some other slippery surface while the other is on dry pavement, slip will occur at the low friction side and the torque applied to the non-slipping tire will be limited to the torque generated at the slipping tire. In such circumstances, very little power will be delivered to the wheel on the dry pavement and the vehicle will not be powered forward or backward. Therefore, there is a need to lock the axle halves together in certain situations causing both wheels to spin at about the same speed, irrespective of differing coefficients of friction encountered by the drive wheels.
It is known in the art to selectively lock other drivetrain components using roller/ramp clutch assemblies. For example, the two-way over-running clutch assembly described in U.S. Pat. No. 5,927,456, assigned to NTN Corporation, and hereby incorporated by reference, describes a clutch assembly of a roller ramp variety and the mechanism by which the rollers are retained and biased in the assembly. In addition, the rotation transmission device described in U.S. Pat. No. 5,924,510, also assigned to NTN Corporation, and hereby incorporated by reference, discloses a device which includes a clutch assembly mounted in the transfer case of a four-wheel drive vehicle that can selectively transmit a driving torque.
Typically, these types of over-running clutches must be either engaged or disengaged, requiring the operator of the vehicle to physically switch between the engaged and disengaged state. Therefore, there is a need for a driveline system utilizing an over-running clutch of the type describes above wherein the driveline system includes an electronic control unit adapted to collect vehicle operation data to determine if the over-running clutch should be engaged and to automatically switch the over-running clutch to engaged and disengaged as needed.
BRIEF SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention an over-running clutch assembly comprises an outer race having a cylindrical inner surface and being rotatable about an axis and a case end enclosing a first end of the outer race, an inner race having a segmented (flat or slightly concave) outer surface coaxial with the cylindrical inner surface and defining a gap therebetween. The inner race is rotatable about the axis with rotational movement relative to the outer race. A plurality of ramp surfaces formed at spaced apart locations on the outer surface define a plurality of cammed surfaces on the outer surface of the inner race. A plurality of rollers are positioned between the outer race and the inner race with one of the rollers being located centrally within each of the cammed surfaces and each of the rollers having a diameter less than the gap between the center of the cammed surface on the inner race and the cylindrical inner surface of the outer race. A retainer interconnects all of the rollers and causes the rollers to circumferentially move in unison with one another. The retainer is rotatable about the axis with limited relative rotation with respect to the inner race. A first biasing element is supported on the retainer to radially bias the retainer position relative to the inner race such that each of the rollers is held in the center of the flat cammed surfaces on the inner race. An actuation disk is connected to the retainer by a means which allows some axial movement of the actuation disk with respect to the retainer toward the case end. The preferred method would include a series of retainer tabs extending axially from one end of the retainer and notches which are adapted to engage the retainer tabs, thereby preventing circumferential or relative rotational motion of the actuation disk relative to the retainer and allowing axial motion of the actuation disk relative to the retainer. There are at least two, and preferably four, tabs extending outward to engage notches within the actuation disk. A second biasing element is disposed between the actuation disk and the inner axial surface of the case end to bias the actuation disk away from the case end.
The clutch assembly includes an actuator to selectively overcome the second biasing element to force the actuation disk into contact with the case end, wherein rotation of the outer race and case end with respect to said inner race is frictionally transferred to the actuation disk and the retainer, overcoming the first biasing element, thereby moving the rollers along the ramp surfaces to a position where the rollers engage and wedge between the inner and outer races to prevent relative rotation between the inner and outer races.
Further, either the actuation disk, or the axial inner surface of the case end includes an undercut region which initially reduces the amount of surface area contact between the actuation disk and the axial inner surface of the case end. After initial contact has been made between the actuation disk and the case end, the actuation disk can deflect, thereby allowing the undercut portions between the actuation disk and the case end to contact as well. When the actuator is deactivated, The deflected portions of the actuation disk will be biased to spring back away from the case end, thereby allowing the second biasing element to bias the actuation disk away from the axial inner surface of the case end with less resistance due to surface tension.
REFERENCES:
patent: 1321618 (1919-11-01), Fynn
patent: 1599389 (1926-09-01), Aiken
patent: 1890973 (1932-12-01), Drexler et al.
patent: 1948196 (1934-02-01), Auperin
patent: 2038985 (1936-04-01), Browne
patent: 2049798 (1936-08-01), Booth et al.
patent: 2181700 (1939-11-01), Leichsenring, Jr.
patent: 2379829 (1945-07-01), Russell
patent: 3324744 (1967-06-01), Roper
patent: 3388779 (1968-06-01), Roper
patent: 3430519 (1969-03-01), Roper
patent: 3448636 (1969-06-01), Roper et al.
patent: 3517573 (1970-06-01), Roper
patent: 4799395 (1989-01-01), Janiszewski
patent: 4867291 (1989-09-01), Holman et al.
patent: 4955853 (1990-09-01), Bausch
patent: 5279401 (1994-01-01), Stall
patent: 5286239 (1994-02-01), Ito et al.
patent: 5366041 (1994-11-01), Shiraishi et al.
patent: 5366421 (1994-11-01), Hirota
patent: 5474164 (1995-12-01), Berger
patent: 5682971 (1997-11-01), Takakura et al.
patent: 5776288 (1998-07-01), Stefanutti et al.
patent: 5924510 (1999-07-01), Itoh et al.
patent: 5927456 (1999-07-01), Monahan et al.
patent: 6-58378 (1994-03-01), None
English Abstract of Japanese Patent No. 6-58378.
Goto Shiro
Okada Koichi
Brinks Hofer Gilson & Lione
NTN Corporation
Rodriguez Saul
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