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Title: The effects of operating conditions on the hydrodynamic lubricant film thickness at the piston-ring/cylinder liner interface of a firing diesel engine
Author: Sochting, Sven
Awarding Body: University of Central Lancashire
Current Institution: University of Central Lancashire
Date of Award: 2009
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Conventional investigations into the performance of piston-rings in internal combustion engines are performed at relatively low speeds and consider only steady state operation conditions. Loss of power in internal combustion (IC) engines is becoming an increasing issue when they are operated at high engine speeds. This project is directed at developing technology to establish whether this phenomenon is influenced by a lubricant related effect. In a normal operating environment automotive engines typically operate under transient operating conditions. These rapid changes in operation conditions may influence the thickness of the hydrodynamic film which lubricates the interfaces between the piston-ring and liner. During this project two capacitance methods were employed in a fired compression ignition engine, an amplitude modulated (AM) system originally developed by Grice and a new "high speed" capacitance technique based on a frequency modulated principle. The first part of this thesis is concerned with the development and implementation of a new apparatus suitable for measuring the thickness and extent of the hydrodynamic oil film which lubricates the piston-rings and liner. The nature of the working principle of the high speed capacitance measurement system required the design, manufacture, assembly and commissioning of a novel dynamic calibration apparatus. The new system can also be used for static calibration (AM system) of capacitance based distance measuring systems. It uses a manufacturer calibrated closed loop controlled piezo-actuator to present a target relative to the sensor face. Some previous investigations concluded a stable oil film thickness. However, this work shows that there are cyclic variations of the oil film thickness OFT on a stroke to stroke and cycle to cycle basis. A series of measurements was conducted under various fixed speed load points. The effects of using lubricants of different viscosity on the minimum (OFT) between liner and piston ring have been little studied and this work shows that it was possible to speciate measurements of different lubricants. This thesis also describes a measurement of the oil film thickness during abrupt changes in engine operating conditions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Technologies not elsewhere classified