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Wideband Acoustical Holography (WBH), which is a monopole-based, equivalent source procedure (J. Hald, “Wideband Acoustical Holography,” INTER-NOISE 2014), has proven to offer accurate noise source visualization results in experiments with a simple noise source: e.g., a loudspeaker (T. Shi, Y. Liu, J.S. Bolton, “The Use of Wideband Holography for Noise Source Visualization”, NOISE-CON 2016). From a previous study, it was found that the advantage of this procedure is the ability to optimize the solution in the case of an under-determined system: i.e., when the number of measurements is much smaller than the number of parameters that must be estimated in the model. In the present work, a diesel engine noise source was measured by using one set of measurements from a thirty-five channel combo-array placed in front of the engine.

Component sound quality is an important factor in the design of competitive diesel engines. One component noise that causes complaints is the gear rattle that originates in the front-of-engine gear train which drives the fuel pump and other accessories. The rattle is caused by repeated tooth impacts resulting from fluctuations in differential torsional acceleration of the driving gears. These impacts generate a broadband, impulsive noise that is often perceived as annoying. In most previous work, the overall sound quality of diesel engines has been considered without specifically focusing on predicting the perception of gear rattle. Gear rattle level has been quantified based on angular acceleration measurements, but those measurements can be difficult to perform. Here, the emphasis was on developing a metric based on subjective testing of the perception of gear rattle.

A project is described where spherical beam-forming was used to perform real time evaluation and development of an automotive dash silencer assembly. By eliminating the iterative laboratory sound transmission loss testing, significant advantages were achieved in part development. These advantages include a reduction in development cost and time, reduced part cost, and lower part mass. Reducing the time to develop lighter and less expensive sound package parts was the most obvious benefit of the project, but the process also: 1) eliminated the time and cost to procure competitive parts; 2) allowed the evaluation of the parts in-vehicle rather than on a laboratory buck; and 3) reduced the time required with the development vehicle.

For the purpose of this paper the author will use VVT (Variable Valve Timing) to describe the function of these components. Other common names are VCT (Variable Camshaft Timing), cam phasers, VVT's were introduced in Japan in the late 1990,s in series production. The benefit to the end user is improved fuel economy, an increase in the power output and a reduction in emissions. Globally there are 8 major suppliers of VVT assemblies. The purpose of this paper is to compare the various systems from the selection of PM materials and the subsequent post operation processes specifically related to sprockets.

This paper describes the successful development of an active muffler system for the Detroit Diesel 6V-92TA industrial diesel engine used in a generator set application. The active muffler analyzes the structure of the exhaust sound and generates ‘anti-noise’ through loudspeakers. The ‘anti-noise’ is equal in magnitude and 180 degrees out of phase with the exhaust sound. The exhaust sound and ‘anti-noise’ cancel each other at the exhaust outlet. Adaptive filter techniques are used to update the ‘anti-noise’ signal in response to changes in engine operating conditions. This technique is effective at frequencies less than 500 Hz, where a significant portion of the exhaust sound is concentrated. Combined with a low flow restriction passive silencer to attenuate primarily high frequency sound, exhaust noise is reduced well below levels emitted by conventional passive mufflers.