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This paper shows results of an experimental study based on a passenger car diesel engine: The piston temperature reduction potential of advanced gallery cooling concepts compared to the standard gallery cooling solution has been investigated. Therefore, different piston cooling concepts featuring one or two oil nozzles per cylinder and combined with compatibly designed cooling galleries have been tested. The influence of the parameters cooling gallery shape and oil nozzle configuration relative to the piston on the piston temperature has been analyzed. The use of suitably adapted advanced piston cooling concepts results in significant improvement of cooling efficiency compared to the established gallery cooling solution.

Reducing piston related noise in internal combustion engines is generally not a question of meeting legislatory limits but more often related to customer annoyance and subjective complaints. In the daily work of the component development engineer audible noise in the vehicle often is the first and most important guideline for component optimisation. The paper deals with improving several piston related noise types using vibration analysis, measurement of piston secondary motion, subjective noise assessment methods based on artificial head noise recording techniques and the calculation of noise excitation using a state of the art computer model with consideration of piston elasticity. All methods are combined to solve the NVH problems in a joint effort. The paper describes the mechanism of excitation, perceived noise emission and its relation to cylinder block vibration. It also demonstrates the correct piston layout for minimum noise.

The consumption of lubricating oil must be substantially reduced to meet the 1991 and 1994 EPA particulate emission standards. The main factors that have to be considered to achieve low oil consumption are analysed in this paper. These factors are: Operation of the ring seal (pressure balancing), piston secondary motion, piston oil drainage features, liner distortion and piston ring conformability as well as liner surface roughness. From the analysis a piston / piston ring design concept for '91 emission targets is derived that is able to reach very low oil consumption figures in the important high speed / part load range as well as a good oil consumption at rated power.