No abstract

Electric coolant pumps for IC engines are under development by a number of suppliers. They offer packaging and flexibility benefits to vehicle manufacturers. Their full potential will not be realised, however, unless an integrated approach is taken to the entire cooling system.The paper describes such a system comprising an advanced electric pump with the necessary flow controls and a supervisory strategy running on an automotive microprocessor. The hardware and control strategy are described together with the simulation developed to allow its calibration and validation before fitting in a B/C class European passenger car. Simulation results are presented which show the system to be controllable and responsive to deliver optimum fuel consumption, emissions and driver comfort.

European regulations set the emissions requirements for new vehicles at 130 g CO 2 /km, with an additional 10 g CO 2 /km to be achieved by additional complementary measures, including gear shift indicators. However, there is presently little knowledge of how much fuel or CO 2 could actually be saved by the introduction of gear shift indicators, and there is no consensus on how these savings should be quantified. This study presents a procedure which allows these savings to be quantified over a New European Driving Cycle, and explores the trade-off between fuel savings and drivability. A vehicle model was established and calibrated using data obtained from pedal ramp tests conducted at steady speed using a chassis dynamometer, significantly reducing the time required to generate a calibration data set when compared with a steady-state mapping approach. This model was used for the optimisation of gear shift points on the New European Driving Cycle for reduced fuel consumption subject to drivability constraints. During model validation the greatest fuel saving achieved experimentally for a warm engine was 3.6% over the New European Driving Cycle, within the constraints imposed using subjective driver appraisal of vehicle drivability. The same shift strategy for a cold start driving cycle showed a fuel saving of 4.3% over the baseline, with corresponding savings in CO 2 of 4.5% or 6.4 g CO 2 /km. For both hot and cold tests the savings were made entirely in the urban phase of the New European Driving Cycle; there were no significant differences in fuel consumption in the extra-urban phase. These results suggest that the introduction of gear shift indicators could have a substantial impact, contributing significantly towards the 10 g CO 2 /km to be achieved by additional complementary measures when assessed in this way. It is not clear whether these savings would translate into real world driving conditions, but for legislative purposes an assessment procedure based on the New European Driving Cycle remains a logical choice for simplicity and continuity.

The work presented here seeks to compare different means of providing scavenging systems for an automotive 2-stroke engine. It follows on from previous work solely investigating uniflow scavenging systems, and aims to provide context for the results discovered there as well as to assess the benefits of a new scavenging system: the reverse-uniflow sleeve-valve.Importantly, it was found that existing experiential guidelines for port angle-area specification for loop-scavenged, piston-ported engines using crankcase compression could also be applied to all of the other scavenging types, this having been done here in order to provide a starting point for the work. This important result has not been demonstrated before for such a wide range of architectures. The optimizer employed then allowed further improvements to be made over the starting point. The paper therefore presents a fundamental comparison of scavenging systems using a new approach, providing insights and information which have not been shown before.

The work presented here seeks to compare different means of providing uniflow scavenging for a 2-stroke engine suitable to power a US light-duty truck. The three different configurations which could utilize this type of scavenging system that were investigated are (1) the opposed-piston engine, which has been applied to aircraft propulsion as well as engines for power generation and rail traction, (2) the poppet-valve uniflow configuration, as exemplified by the Detroit Diesel 2-stroke engine, and (3) the sleeve-valve uniflow engine, the unusual arrangement of which was used in the Rolls-Royce Crecy, intended for high-speed interceptor aircraft application. All of these concepts were compared in terms of indicated fuel consumption for the same cylinder swept volume, and a new methodology for optimization was developed using a one-dimensional engine simulation package which also took into account charging system work. As a result of this work it was found that the opposed-piston configuration provides the best attributes since it allows maximum expansion and minimum heat transfer. It was found that existing experiential guidelines for port angle-area specification for loop-scavenged, piston ported engines using crankcase compression could also be applied to all of the other scavenging types. This has not been demonstrated before.