Sprungmasse

Sprungmasse, in automotive engineering, refers to the portion of a vehicle’s mass that is supported by the suspension springs. It generally includes the vehicle’s body and chassis, occupants, cargo, and any components connected to the sprung structure, such as the engine and transmission, though the exact boundary can vary with mounting arrangements.

By contrast, the unsprung mass consists of parts directly connected to the wheels and not supported by springs: wheels and tires, brakes, axles, and portions of the suspension hardware themselves. The ratio of sprung to unsprung mass influences ride comfort, handling, and the ability of the suspension to keep the wheels in contact with the road.

Dynamics play a central role: the sprung mass, together with suspension stiffness and damping, defines the system’s natural frequency, approximately ωn = sqrt(ks / ms). A higher sprung mass lowers this frequency, which can affect how the body responds to road irregularities; reducing sprung mass generally raises the natural frequency and can improve ride quality and wheel control, though it must be balanced against strength and payload.

Design implications: engineers aim for a favorable sprung-to-unsprung mass ratio to enhance ride, handling, and road feel. Reducing sprung mass can allow a softer suspension without transmitting large accelerations to occupants, but trade-offs exist with structural integrity and payload capacity. Lightweight construction and optimized subframes are common approaches.

Measurement and notes: Sprung mass is a lumped-mass concept used in vehicle dynamics models. In practice, it is the mass supported by the springs, including major components and occupants; exact values vary with vehicle type and layout.