Comfort up – CO2 emissions and costs down
Schaeffler’s clutch disc with centrifugal pendulum-type absorber fulfills high comfort requirements and reduces CO2 emissions
Trends in engine design such as downsizing pose major challenges to developers. One of these challenges is how to eliminate torsional vibrations in the drive train. Schaeffler’s drive train specialists at LuK have now developed an economical alternative in the form of a clutch disc with torsion damper and centrifugal pendulum absorber. In terms of efficiency it ranks between conventional dual mass flywheels and clutch discs with torsion dampers. Potential applications include internal combustion engines with torque ranges up to 250 Nm and high tractive force even at low speeds.
Currently, either clutch discs with torsion dampers or dual mass flywheels are used to reduce rotational irregularity in internal combustion engines for the gearbox input in vehicles with manual transmissions. The dual mass flywheel (DMF) developed over 30 years ago is most certainly the best method of damping torsional vibrations in the drive train. The introduction of the DMF with centrifugal pendulum absorber around 10 years ago significantly increased this damping effect. Thus, the active principle of the centrifugal pendulum absorber is transferred to other drive train solutions by Schaeffler. It is used in mass production within the torsion damper of the torque converter clutch. Also the application within a conventional drive train comprising a rigid flywheel and a clutch disc with torsion damper has been investigated. The results of some initial development work a few years ago showed that incorporating a centrifugal pendulum absorber into the clutch disc posed a special chal lenge. However, in the meanwhile a solution could be found and its application in high-volume production has now been planned for the near future.
The design process for the clutch disc with centrifugal pendulum absorber involves efficiently incorporating as much pendulum mass as possible in the smallest of spaces while keeping the increase in mass moment of inertia limited. The decisive innovation involves designing the centrifugal pendulum absorber as a trapezoidal pendulum. In contrast to a parallel pendulum, the pendulum mass of a trapezoidal pendulum not only carries out a lateral pendulum movement but also a rotational movement. As a trapezoidal pendulum, the mass used achieves the highest level of efficiency, which is also consistent with increasing the mass moment of inertia as small as possible.
Six different vehicles were simulated and tested with prototypes in order to demonstrate the effectiveness of the new product. In all the tested vehicles, the clutch disc with centrifugal pendulum absorber ranks midway between the conventional system and the DMF in terms of performance and system costs. It even achieves the same lowest driveable speed as with a DMF, which allows for the same economical driving style. This means the clutch disc with centrifugal pendulum absorber is a product that fulfills requirements in terms of comfort where a conventional system is no longer sufficient and a DMF is not absolutely necessary.