Dual mass variable inertia flywheel assembly

Details Dual mass variable inertia flywheel assembly Dual mass variable inertia flywheel assembly

1999-11-03

2001-04-17

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

With means to vary drive ratio or disconnect drive

Reexamination Certificate

active

06217475

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention generally relates to flywheels used in vehicle drivelines. More particularly, this invention relates to a flywheel assembly that has a selectively variable moment of inertia that controls torsional vibrations in a vehicle driveline.
Vehicle drivetrains or drivelines typically include an engine with a rotating output shaft. A flywheel rotates with the output shaft to provide a rotating driving force to an input shaft on a transmission gear box. The transmission gear box provides a desired gear ratio to a transmission output shaft to drive the wheels of the vehicle. Most driveline assemblies include a clutch for selectively coupling the driving torque from the engine to the transmission. Along with the clutch a torsional damper is typically included to decrease torsional vibration along the drivetrain.
One feature that has long been desired is a dual mass flywheel that is capable of reducing the amount of torsional vibration along the drivetrain. Many difficulties have been encountered when attempting to design such a dual mass flywheel. Most, if not all, dual mass flywheel arrangements that have been proposed to date have proven unsuccessful or, at best, of limited value.
Additionally, it is very desirable to provide a flywheel arrangement that has a variable inertia to compensate for vibrations in the vehicle drivetrain. Prior to this invention, no one has proposed an arrangement where a variable inertia flywheel compensates for such circumstances.
This invention provides a unique dual mass arrangement with a variable inertia so that torsional vibrations along the vehicle drivetrain are effectively eliminated. Additionally, this invention provides an arrangement that enhances vehicle performance such as acceleration and fuel economy.
SUMMARY OF THE INVENTION
In general terms, this invention is a dual mass, variable inertia vehicle flywheel assembly. A flywheel member is adapted to be moved by a rotating engine output member such as an engine output shaft. A planetary gear arrangement cooperates with the flywheel member to provide a variable moment of inertia. The planetary gear arrangement is selectively moved into a first operative position where selected portions of the planetary gear arrangement rotate with the flywheel member. In this first operative position, a first moment of inertia exists. The planetary gear arrangement also is selectively moved into a second operative position where selected portions of the planetary gear arrangement rotate with the flywheel member. In this second operative position, a second moment of inertia exists.
Having the planetary gear arrangement components rotate with the flywheel member provides a dual mass flywheel assembly. The inventive arrangement provides excellent torsional vibration control. A vibration damper preferably is between the flywheel member and the planetary gear arrangement.
By selecting which of the components of the planetary gear arrangement rotate with the flywheel as driving torque is provided to the vehicle transmission, the moment of inertia of the flywheel assembly is varied. This allows a lower moment of inertia at vehicle start-up and in the lower range of gears, such as first through fifth gears. A second, higher moment of inertia is provided by controlling the operation of the planetary gear arrangement when higher gear ratios, such as sixth through tenth, are chosen.
A system designed according to this invention provides a dual mass flywheel assembly that has a variable moment of inertia because a different effective mass is rotated depending upon the operating position of the planetary gear arrangement. Moreover, varying the moment of inertia of the flywheel arrangement is effective for eliminating torsional vibrations along the drivetrain components, especially when gear ratios are selected that correspond to the natural resonant frequency of the drivetrain.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.


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