Viscosity damper

In the crankshafts of marine diesel engines , torsional vibrations occur, stimulated by inertial forces and gas forces. These generate alternating torsional stresses in the crankshaft. When an excitation frequency coincides with the natural frequency of the crankshaft, particularly high loads can occur. A torsional vibration damper is attached to the end of the crankshaft so that the loads do not become too high. Due to the further development or increase in performance (i.e. higher gas forces) of the engines, the effect of the plane damper was no longer sufficient. Instead, a viscosity damper was now used. The sleeve spring damper is a further development .

construction

The viscosity damper consists of a flywheel on the secondary side and a primary part that is directly connected to the crankshaft. The primary part is a housing that is closed on all sides. The secondary mass is rotatably mounted in the housing. There is a damper fluid between the housing and the flywheel. The strength of the friction between the secondary part and the primary part depends on the play between the two parts and on the viscosity of the damper fluid.

Mode of action

A relative movement occurs between the housing and the secondary part even with the slightest crankshaft vibrations. This removes vibration energy from the system and leads to a reduction in the stress on the crankshaft. At low frequencies and small amplitudes , the damper has little effect. The damping effect increases roughly proportionally with the vibration speed.

history

In the years 1970 to approx. 1986, MaK engines were equipped with this type of damper if necessary.

source

• Ernst-Günter Kroos: "About the structure, mode of operation, operating behavior and maintenance of MaK torsional vibration dampers"