Design and Evaluation of Output Profile Shaping of an Internal Combustion Engine for Noise & Vibration Improvement

Engine torque profile shaping strategies have been proposed to reduce noise & vibration for passenger cars. However, it has not been sufficiently studied that feasible torque profile for vibration suppression is dependent on engine speed and target torque shape. On the other hand, combustion pressure profile shaping strategies have been proposed to reduce noise. However, there is almost no research of the quantitative evaluation of contribution of combustion pressure profile. First, the torque profile shaping was studied. Pre-compensated torque and 2-step torque were selected as typical target torque profiles. An effectiveness of vibration suppression by two torque profiles was evaluated by both drivetrain vibration model and engine torque profile model which have been established well. As a result of studying the torque profile shaping, timing of torque rise by the 2-step torque generation is delayed or advanced. Torque profile by the precompensation is deformed in steep change part. Relative degree of deterioration in 2-step torque generation is smaller than that of the pre-compensator. Second, the combustion pressure profile shaping was studied. A combustion noise generation model was constructed by the combustion pressure, a vibration transfer function in an engine structure, and a radiation factor at the engine surface. The surge in combustion pressure was modeled as triangular shape projection and analyzed in frequency domain to evaluate a contribution to combustion noise. As a result of studying the combustion pressure profile shaping, new analysis method by these models is proposed, so that radiation pressure for quantitative evaluation be obtained.