Sleeve spring damper

In the crankshafts of marine diesel engines , torsional vibrations occur, stimulated by mass 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 and the viscosity damper was no longer sufficient. Instead, a sleeve spring damper is now used.

construction

The sleeve spring damper consists of a drive star that is firmly connected to the crankshaft. The flywheel on the secondary side is rotatably mounted on the drive star. Sleeve spring packages are located between the two parts. Half of the spring assemblies are accommodated in the drive spider and half in the secondary part. The more spring assemblies that are installed, the greater the stiffness of the elastic connection. To protect the spring assemblies from overstressing caused by excessive twisting of the secondary mass, stroke limiting bolts are built into the sleeve springs. The moving parts are fixed in the axial direction by side covers. They also seal off the vibration damper from the outside. The vibration damper is filled with oil via the crankshaft during operation.

Mode of action

A relative movement between the primary and secondary part occurs even with the slightest crankshaft vibrations . This compresses the sleeve spring assemblies. Due to the friction between the spring leaves and the displacement of oil, vibration energy is withdrawn from the system and thus leads to a reduction in the crankshaft stresses.

history

MaK motors have been equipped with this type of damper from around 1974 until today .

source

Ernst-Günther Kroos: About the structure, mode of operation, operating behavior and maintenance of MaK torsional vibration dampers .