The Sachs planetary dual mass flywheel (DMF) is the key to first-class passenger car and commercial vehicle drivability. The driver and occupants are aware of reduced driveline and body noise and enjoy smoother travel with more pleasant gear shifts. The use of advanced and multi-functional components now enables the Sachs dual mass flywheel to be installed also in lower midsize category cars.
Problem
The engine‘s ignition-induced rotational speed irregularity causes torsional vibration in the vehicle‘s driveline. At a given speed the ignition frequency is equal to the natural frequency of the driveline so that extremely high vibration amplitudes occur that cause transmission rattle and vibration.
Solution
In the Sachs planetary dual mass flywheel, the planetary gear and the torsional damper are incorporated into the flywheel. For this purpose, the flywheel is divided into a primary and a secondary mass, hence the name „planetary dual mass flywheel”. Rattle and booming noise are now a thing of the past.
Sachs planetary DMF: The advantages for the driver
- Fuel consumption is reduced, since idle speed is lowered and from idle speed the car can be driven at full throttle.
- High level of acoustic refinement, due to the suppression of annoying rattling and body boom.
- Good refinement even during load reversals, thanks to vibration damping. Jolts are eliminated.
- Improved operating comfort because fewer gear shifts are required. No unpleasant booming noise that would force the driver to make gear shifts too early.
- Improved gear shift, since lower mass moment of inertia of the clutch disc without torsional damper results in reduced shifting effort.
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Sachs planetary DMF: The principle facts for the design engineer
- Excellent vibrations damping quality through all engine-speed.
- Effortless engine start, short start and stop behavior.
- Good tuning capability thanks to springs in series and spring sets with various stiffness ratings, guided by plastic sliding blocks and spring caps, which keeps the springs from going solid.
- Planet gears increase the dynamic mass moment of inertia.
- Grease-filled for long service life.
- Combination of three mechanisms with damping effect:
- friction (friction bearings, centrifugal force)
- vibration damping proportional to speed
- inertia of planetary gear
- no special friction device needed |
