Search Results

The efficiency of lubricated machine elements such as transmissions, crankcase engines, and hydraulic pumps depends strongly on the friction properties of the lubricant employed. For the design of modern, highly efficient lubricants it is thus essential to understand the influence of the components of the lubricating fluid in terms of film formation and consequent friction. The influence of Polyalkylmethacrylate (PMA) Viscosity Index Improvers on those important parameters has been studied by means of optical interferometry and friction testing. Low friction coefficients and positive contributions to the boundary film thickness of the lubricant were obtained when composition and architecture of the polymeric VII were appropriately designed.

The noise and ride behavior of a vehicle can be significantly affected by vibrations transferred from the engine through the engine mounts to the chassis. Considering the engine, engine mounts, and chassis as individual components limits the potential gains on the overall vehicle performance. By describing the engine, engine mounts, and chassis as a vibrational system, emphasis can be placed on the capacity for engine mounts to improve the vibrational characteristics of a vehicle. The focus of this paper is on the role of engine mounts in the optimization process of vehicle vibrational and acoustic behavior. Passive, semi-active, and fully active engine mount designs are discussed. Characterization of the different effects of these types of mounts on noise and vibration performance is provided based upon analytical and experimental results.

The ride and noise behavior of a vehicle can be significantly affected by vibrations transferred from the engine to the chassis through the engine mounts. For this reason, special attention has to be paid to the design of the engine mount system right from the beginning of a new car development program. Only optimizing the engine mount while considering it as an isolated component limits the potential gains in regard to the overall vehicle performance. Therefore, right from the conception phase, the mounting system has to be considered as an integral part of the vehicle vibrational system. With the suggested approach, based on analytical and experimental results, the optimization of the mount system can lead to a good overall vehicle performance at low cost. The focus of this paper is placed on the role of engine mounts in the optimization process of the vehicle vibrational and acoustic behavior.

The ride and noise behavior of a vehicle is significantly affected by vibration transferred from the engine to the chassis through the engine mounts. In this paper conception and design strategies for engine mount systems based upon calculation and experimental methods are discussed. Analyses for static and dynamic engine loads and for idle shake vibrations are presented. The finite element analysis is applied to optimize a mount's rubber spring geometry. Furthermore, the role of the transfer path analysis in the optimization of an engine mount system is illustrated. Passive and semi-active engine mounts that significantly improve the isolation of the idle shake vibration will be discussed. Finally, fully active vibration absorbers which can be applied to solve noise problems, even at a late stage of a new car development program will be presented.

A vehicle's structure vibration leads to perceivable accelerations at the steering wheel, the seat rails and the floor panels; additionally, these vibrations cause structure borne noise which contributes to the sound pressure level in the passenger's compartment. The perceivable structure accelerations and the sound pressure level constitute criteria for evaluating a vehicle's noise and vibration behavior. Consequently, improving the noise and vibration behavior is tantamount to reducing the vibration amplitudes of the vehicle structure. The operating engine causes engine mount forces which provoke the structure vibration. After the engine mount forces are calculated, the structure vibrations are simulated with a vehicle structure model described by transfer functions that relate the engine mount forces to the accelerations of all selected structure points where the vibration is supposed to be analyzed.