Powertrain Modal Characterization to Reduce Vehicle In-cab Noise

NVH performance of powertrain [PT] is a critical parameter for vehicle NVH refinement. Ingress of PT-radiated noise to the cabin can be restricted by blocking the air born noise paths using combination of sealing, shielding and absorption. Isolation of vibrations to the body is achieved by soft rubber-mounting of PT at idling and low speeds. At higher speeds, when PT-support brackets, Frame, Body and other driveline components go into self-resonance, isolation provided by the rubber-mounts have limitations. Control of excitation at source itself will be a solution on this background [1].

In presence of strong transfer paths through driveline support, a direct correlation between flexural modes of PT and In-cab booms can be observed during vehicle operation [2].

Current work presents an overview and approach for refinement of PT including use of front-loading technique in the early design stage for modal refinement, testing and correlation. A comparison between relevant NVH parameters of the vehicle with an existing and new PT assembly is also included as an evidence to support relevance of the work.