192 clutches and power-stop control – Clutch and gear
Reexamination Certificate
1999-09-10
2001-06-19
Bonck, Rodney H (Department: 3681)
192 clutches and power-stop control
Clutch and gear
C192S035000, C192S1030FA, C475S339000
Reexamination Certificate
active
06247566
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for transmitting torque between two rotatable, coaxial shaft members, the device containing a number of alternate clutch discs connected to the two shaft members and engageable to counteract differential rotational speed between the shaft members.
BACKGROUND OF THE INVENTION
Devices for transmitting torque between two rotatable shafts are known from numerous patent publications, one typical example being U.S. Pat. No. 5,469,950 from the same applicant. Here the two shafts are the output shafts of a vehicle differential mechanism. The device may accordingly in this case be called a differential brake. There may, however, be other instances when it is desired to counteract a certain rotational speed differential between two shafts, a typical example being the two shafts to the driven front and rear axle, respectively, of a four-wheel-drive vehicle.
There may be different techniques to obtain the counteracting of the rotational speed differential, but several of the known solutions rely on a hydraulic system. The device according to the patent mentioned above is one example hereof.
Hydraulic systems for the above purpose may be rather complicated and accordingly expensive to manufacture and service.
The control of different systems in a road vehicle is to a growing extent electrically performed, and different control systems often interact. The control signal to a device of the kind with which the present invention is concerned is most often electrical and is influenced by signals from other on-board systems. It would accordingly seem advantageous not to be forced to use a hydraulic system but rather an electro-mechanical system.
THE INVENTION
For obtaining an improved torque transmitting device of the kind defined above, means for counteracting said differential rotational speed between the shaft members may comprise braking means for braking rotational movement, the rotational velocity in the braking means being proportional to the rotational speed differential between the shaft members.
In this way both the rotational speed differential and the torque transmitted between the shaft members is controlled by means of rotational velocity in the braking means, which gives the possiblity for an improved control independent of internal factors in the device itself.
A practical device for accomplishing the above may according to the invention comprise
gear means connected to the first shaft member,
a pressure plate, which is connected to the second shaft member and is axially displaceable against the clutch discs for their engagement,
transmission means between the gear means and the pressure plate for axially displacing the pressure plate against the clutch discs at a certain rotation differential between the gear means and the pressure plate, and
braking means connected to the gear means for providing a force to the transmission means for its axial displacement.
In this device the gear means is preferably of the planetary type and comprises
a gear wheel attached to the first shaft member and a corresponding gear wheel, which is rotatable on the first shaft member and engages the transmission means,
sets of two planet wheels, which engage the two gear wheels and are arranged on a common axle of a planet holder,
a fixed gear rim in engagement with one of the planet wheels, and
a gear ring, with whose internal gears the other planet wheel is in engagement and which is in engagement with the braking means.
Further, the transmission means may preferably comprise rollers arranged in ramps between the pressure plate and the gear wheel rotatable on the first shaft means. At a relative rotation between the pressure plate and the gear wheel the roller-and-ramp-arrangement will result in an axial displacement.
For obtaining the necessary axial force in this transmission means a compression spring is arranged between the second shaft member and the pressure plate.
The advantage with electrical control and electrical actuation of the device can be obtained in that the braking means comprises an electrical brake consisting of a stator and a rotor on a brake shaft rotationally driven by the gear ring.
REFERENCES:
patent: 3323779 (1967-06-01), Burnett
patent: 5322484 (1994-06-01), Reuter
patent: 5405293 (1995-04-01), Severinsson
patent: 5469950 (1995-11-01), Lundstrom et al.
patent: 5720375 (1998-02-01), Maeda et al.
patent: 5810141 (1998-09-01), Organek et al.
patent: 5884738 (1999-03-01), Joslin et al.
patent: 5954173 (1999-09-01), Sakai et al.
Bonck Rodney H
James Ray & Associates
Westinghouse Air Brake Company
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