Search Results

This paper describes the design measures taken to develop the noise and vibration performance of a new rear suspension and a new drivetrain system for rear-wheel-drive vehicles. The new rear suspension is designed to solve trade-off issues between road noise and handling performance. Despite higher drive torque, booming noise is greatly reduced by the new rear suspension and drivetrain without increasing the vehicle weight or sacrificing fuel economy.

In order to improve radiator fan noise, it is necessary to consider the system's Blade-Passing-Frequency (BPF), in addition to over-all noise reduction. BPF is unpleasant to vehicle passengers and is chiefly caused by the non-uniformity of upstream and downstream flows of the fan rotor. As a result, this noise is remarkably influenced by the layout of heat exchangers, shroud and engine room. Although the BPF noise has conventionally been evaluated experimentally, authors have recently begun considering BPF noise prior to trial. This has been accomplished by developing and applying the BPF Noise Prediction Technique, which consists of a Computational Fluid Dynamics (CFD) analysis and a sound wave propagation theory. This paper explains the prediction technique of the BPF noise, and also reports the results of its accuracy verification.

Fuel atomization is known as an effective means of reducing the exhaust emissions of internal combustion engines. We have focused on a multiple-hole nozzle as a cost-effective atomization method that does not require any auxiliary devices or an external energy source to carry out atomization. In this report, we will discuss the facts that 1) the primary factors of atomization with the multiple-hole nozzle lie in the flow upstream of the nozzle, and 2) the atomization characteristics such as spray droplet diameter and spray spatial distribution when the factors which effect atomization with the multiple-hole nozzle are changed. As a result, with our newly developed 12-hole nozzle injector in an actual engine, we found an HC reduction effect greater than that of a conventional air-assist injector.