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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.

This paper reports development of a measuring device built in a camshaft drive chain sprocket for detecting precise torque fluctuation with minimum change on the valve drive system dynamical characteristics. This torque measuring device (TMD) was designed to measure torque with minimum cross-talk with bending force or lateral force. To realize these functions, the disc portion of a chain sprocket that connects the teeth and the camshaft was carved to make thin plate area so that the strain gages placed on the area may have enough sensitivity to torque fluctuation. The signal from the circuit goes through frequency modulation and is transmitted to demodulation circuit via coil antennas. By this arrangement, almost perfect linearity was observed in the relationship of the TMD output voltage and the applied torque. Using a model cylinder head unit of an in-line four cylinder gasoline engine driven by a variable speed electric motor, the TMD performance was evaluated.

The purpose of the present study is to improve the on-street exhaust noise measurement technique for regulating vehicles emitting unacceptably large exhaust noise. The method under development uses racing operation of engines with a wide-open throttle. Due to the high engine acceleration in this operation, exhaust pulsation amplitudes at resonant speeds may not increase sufficiently to represent the amplitudes under full-load acceleration conditions. To investigate the seriousness of this problem, experiments and numerical simulations were conducted. As a result, the sound level measurement error caused by the insufficient resonance growth was found to be sufficiently small for on-street tests.

One potential method by which to realize better acoustic in-car entertainment with a minimum of space is to adopt very thin Flat-Panel Speakers (FPSs), which use a combination of an array of coils printed on a flexible thin plastic film and permanent magnets. In the present report, the optimal panel material was investigated through experimental modal analysis. The optimal driving unit placement over the board was then determined using FEM based modal analyses. Finally, structural modifications to the sound radiating board in order to obtain a wider efficient frequency range were investigated experimentally. Among several design alternatives, satisfactory results were obtained by either dividing the sound radiating board into virtually independent sub-panels or adding resilient damping material supported by a restraining material.

During acceleration, engine combustion is the major sound source in passenger vehicles.[1] This sound characterizes the overall impression made by the vehicle. Automobile manufactures have been developing engines to have better sound characteristics since the late 1980s.[2] However, fundamental and systematic knowledge of the relationship between the basic structural dynamics of the engine and its sound characteristics has not yet been reported. In addition, in the design stage, engine designers were not previously able to listen to the sound generated by the engines. This paper introduces a tool that synthesizes engine combustion sound by specifying the combustion process and a basic engine structural dynamics model having a small number of parameters. Using this tool, the authors obtained important relationships between combustion process and subjective sound characteristics evaluation scores.

A formula type racing-car was designed and built for the “Formula SAE” competition. Lightweight design was achieved separately in two areas, i.e. the pipe frames and bulkheads, by employing two different strategies. In the pipe frame design, the stretch method was used. The baseline design employed the minimum number of pipes required to make the structure statically stable. After this, reinforcements were attached one-by-one, until the rigidity reached a satisfactory level. In the bulkhead design, weight reduction was achieved using a voxel approach and topology optimization. The bulkhead was divided into finite elements that have the same shape and size. Starting from a solid board, relatively low-stress parts were removed from the model in a step-by-step manner. The weight of the final design is less than 50% of that of the solid board.

Hydraulic engine mounts(HEM) are replacing conventional rubber mounts to provide better ride quality and to reduce noise. However, detailed analysis of the HEM is needed to predict ideal performance conditions. In this study, the optimum design of a HEM is modelled using design optimization theory for a dynamic absorber. After determining ideal behavior by simulation, an experimental mounts is designed and tested to verify the model.

The relationship between the spectrum structures of passenger compartment noise and the results of subjective evaluations of sound quality-has been studied on a fron-wheel-drive car with a four cylinder engine. As a result of an analysis using a car interior noise simulator, which is a kind of digital sound shynthesizer, most of the sound quality indicies such as the crank rumble noise, the roughness or unstable characteristics, and the muddiness were found to be related to the structure of engine revolution harmonics and to the strength of fourmants. Further, the physical mechanisms which characterize these spectrum structures were identified through both engine running tests and shaker tests. As a results, the dominant factors governing sound quality problems were found to be the crankshaft bending or torsional vibration coupled with the total power plant vibration shystem.

In order to clarify the generation mechanism of engine noise, which is a significant problem in the fast-burn engine, the behavior of the crankshaft, the force transferred to the main bearing caps supporting the crankshaft, and the deformation of the cylinder block were analyzed during engine firing. As a result, it was determined that the crankshaft which deflects due to inertial force pushes the bearings violently under combustion pressure and causes intense fore-and-aft vibration of the bearings, which in turn causes vibration of the cylinder-block skirt. This is a main cause of combustion noise.