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The interaction of three bio-lubricant base oil candidates with seventeen combinations of surface treatment was studied, comparing wear scar volumes and coefficient of friction results. Substrates were initially ground, then a combination of superfinished, Dymon-iC™ DLC, an impact technique of ultra-fine shot blasting method doped with Tin and Molybdenum Disulfide, a calcium based chemical dip containing calcium sulfate and nano fullerene, were used. DLC is well reported to reduce friction. Some reports suggest wear in coated contacts is independent of the type of lubricant used, whilst others report that bio-lubricants offer reduced friction and wear in combination with DLC. Shot blasting can also reduce wear and friction, due to the surface dimples acting as lubricant reservoirs, making hydrodynamic lubrication more likely.

The measurement of pressure at a contact in engine parts is important, because it is frequently contact stresses that lead to failure by seizure, wear, or fatigue. Whilst an interface might appear smooth on a macro-scale, it consists of regions of asperity contact and air gaps on a micro-scale. The reflection of an ultrasonic pulse at such a rough contact can be used to give information about the contact conditions. The more conformal the contact, the lower the proportion of an incident wave amplitude that will be reflected. In this paper, this phenomenon has been used to produce maps of contact pressure at three automotive component contacts: a cam/follower interface, a valve tip contact and a tripode drive joint. An ultrasonic pulse is generated and reflected at the interface, to be received by the same piezo-electric transducer. The transducer is scanned across the interface and a map of reflected ultrasound (a c-scan) is recorded.

A study has been carried out to investigate the influence of soot contaminated automotive lubricants in the wear process of engine valve train contacts. Previous research on this topic has been performed from a purely generic and theoretical point of view. Testing has been carried out using standard testing techniques with very little relevance to real engine conditions or components. In this study the conditions under which wear occurs was investigated using tests with actual valve train components. The objective of the work was to develop a knowledge base of wear data for a variety of lubricated reciprocating valve train components. This will increase the understanding of the wear mechanisms that occur within a contaminated contact zone, which will be used in the future development of a predictive valve train wear model.

Wear problems will continue to occur with engine components even with changing design and the introduction of novel materials. Very few wear models for engine components exist, however, so it is difficult for engineers to easily establish how materials and components will perform and costly engine testing programs have to be carried out. Those models that do exist are often complex, difficult to use and written in software that is not available within many organisations. The use of browser-enabled software applications is becoming increasingly common in large, multi-location organisations to make the delivery and support of engineering tools more efficient, so it would be beneficial if wear modelling software was available in this format. In this project, work has been carried out to further the development of an existing valve recession model to provide an easy to use variant for use in industry.

The paper presents a novel method for the measurement of lubricant film thickness in the piston-liner contact. Direct measurement of the film in this conjunction has always posed a problem, particularly under fired conditions. The principle is based on capturing and analysing the reflection of an ultrasonic pulse at the oil film. The proportion of the wave amplitude reflected can be related to the thickness of the oil film. A single cylinder 4-stroke engine on a dyno test platform was used for evaluation of the method. A piezo-electric transducer was bonded to the outside of the cylinder liner and used to emit high frequency short duration ultrasonic pulses. These pulses were used to determine the oil film thickness as the piston skirt passed over the sensor location. Oil films in the range 2 to 21 μm were recorded varying with engine speeds. The results have been shown to be in agreement with detailed numerical predictions.

A photoelastic stress analysis technique has been used to determine the contact stresses in an automotive chain drive tensioner. The tensioner in normal operation is subject to high magnitude, short duration impact stresses. These stresses are known to cause surface damage, wear, and surface pitting. In order to adequately design the drive system layout, a means for stress quantification is needed. A replica tensioner was made from epoxy resin and tested in a variety of configurations. A simple model has been created to relate the chain link load to the resulting tensioner sub-surface stress field. This model has been used to correlate the observed and predicted location of isochromatic fringes, and hence to evaluate the chain link load from the photoelastic fringe pattern. A series of static load tests were performed to calibrate the apparatus. The tensioner specimen was then assembled in a chain drive test facility.

Although new materials and production techniques are being developed to reduce valve and seat wear, these advances have been outpaced by demands for increased engine performance. At present no rules exist to arrive at a satisfactory valve life. Each wear problem, therefore, has to be investigated, the cause isolated and remedial action taken. The objective of this work was to develop design and failure analysis tools for use in industry to assess the potential for valve recession and solve problems that occur more quickly. A semi-empirical wear model for predicting valve recession has been developed based on data gathered from laboratory simulation experiments. A software program, RECESS, was developed to run the model. Model predictions are compared with engine dynamometer tests and bench tests.