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Technical Paper

An Investigation of Cylinder Pressure as Feedback for Control of Internal Combustion Engines

The advantages of closed, loop over open loop control systems are generally recognised. However, existing engine management systems implement most control functions in open loop because suitable feedback sensors are not available. Even for so-called closed loop air fuel ratio controllers, shortcomings of the exhaust gas oxygen (EGO) sensor limit the potential effectiveness of closed loop control. A more direct measure of the combustion process, such as cylinder pressure, can yield sufficient information for the closed loop operation of many of the combustion control functions; this paper presents the results of a prediction algorithm which can derive a variety of feedback signals from cylinder pressure. Cylinder pressure, together with several combustion variables, including air-fuel ratio, exhaust gas recirculation rate, and NOx HC, CO and CO2 emissions were measured at various operating points.
Technical Paper

Optimization of Heavy-Duty Diesel Engine Transient Emissions by Advanced Control of a Variable Geometry Turbocharger

Ricardo have developed a systematic approach for the design of transient engine control strategies using advanced control techniques. The methodology was initially applied to the design of a testbed speed and torque controller. This enabled complex transient tests to be carried out with equipment normally used for steady-state testing. The same techniques were applied to the design of a controller for a variable geometry turbocharger aimed at vehicle applications. The influence of different control strategies on emissions and fuel economy was evaluated on a heavy-duty diesel engine over a section of the US FTP cycle. Particulate reductions of up to 34% were achieved without increasing NOx.
Technical Paper

Low Emissions Approaches for Heavy-Duty Gas-Powered Urban Vehicles

Natural gas is one of the alternative fuels to diesel being considered for low emissions heavy-duty applications. The favoured operating strategies for low emissions SI gas engines are identified as those with high levels of dilution - stoichiometric operation with EGR, and lean-burn. A well-matched exhaust catalyst is needed to produce the lowest emissions levels. Increasing the accuracy of transient air-fuel ratio control is shown to improve the emissions still further. The most favourable combinations of engine operating strategy and control accuracy are identified with respect to fuel economy and first cost. The Co-Nordic Natural Gas Bus Project is an example of an engine development programme aimed at achieving the lowest possible exhaust emissions levels, and as such uses the lowest emissions approach of a stoichiometric engine strategy with EGR and high accuracy control.
Technical Paper

Injection Timing and Rate Control - A Solution for Low Emissions

This paper describes latest results from the Ricardo heavy duty diesel engine research programme. Using a Diesel Kiki P-TICS II injection system, matched to a low swirl combustion chamber, emission results well within the US 1991 engineering targets have been achieved with good fuel economy. Very low NOx levels have also been demonstrated whilst maintaining good fuel economy and particulate emissions within the 1991 standards. Analysis of results indicates that injection timing and rate control, as embodied in the P-TICS approach, is a key technology for achieving these low emissions with good fuel economy.
Technical Paper

Real-World Emissions Measurements of a Gasoline Direct Injection Vehicle without and with a Gasoline Particulate Filter

The market share of Gasoline Direct Injection (GDI) vehicles has been increasing, promoted by its positive contribution to the overall fleet fuel economy improvement. It has however been reported that this type of engine is emitting more ultrafine particles than the Euro 6c Particle Number (PN) limit of 6·1011 particles/km that will be introduced in Europe as of September 2017 in parallel with the Real Driving Emission (RDE) procedure. The emissions performance of a Euro 6b GDI passenger car was measured, first in the OEM build without a Gasoline Particulate Filter (GPF) and then as a demonstrator with a coated GPF in the underfloor position. Regulated emissions were measured on the European regulatory test cycles NEDC and WLTC and in real-world conditions with Portable Emissions Measurement Systems (PEMS) according to the published European RDE procedure (Commission Regulation (EU) 2016/427 and 2016/646).
Technical Paper

Gasoline Engine Combustion - The High Ratso Compact Chamber

The use of high ratio compact combustion chambers in gasoline engines has been investigated. The objectives of the research are improved fuel economy within a given set of exhaust emission constraints. The effects of a number of parameters such as swirl, compression ratio and combustion chamber geometry have been investigated, and the conclusions are that for Europe, 13:1 compression ratio is feasible and should yield 10% better fuel economy in passenger cars, while for the USA and Japan, 11:1 compression ratio is preferable, and should yield about 5% better fuel economy.
Technical Paper

Engine Transmission Matching to Improve Passenger Car Fuel Economy

A compact passenger car was modified to allow operation with up to six manual gear ratios and up to 35.4 mile/h per 1000 rev/min. Fuel consumption tests were carried out at steady state conditions, over the U.S. Federal urban drive cycle and on the road. Fuel economy improvements of up to 24% were achieved on the road, and up to 25% on the chassis dynamometer over the urban cycle, confirming computer predictions.
Technical Paper

Gasoline Engine Combustion—Turbulence and the Combustion Chamber

A research programme has been carried out to investigate the effects of operating gasoline engines with different combustion systems. The results showed that at high compression ratios (13:1) compact combustion chambers allowed an increase in compression ratio of between 1 and 2½ numbers for a given fuel quality compared to conventional designs. Fuel economy benefits of about 10% could be achieved by using high ratio compact chambers and lean operation.
Technical Paper

Warm-Up Strategies For a Methanol Reformer Fuel Cell Vehicle

With current technology, a PEM fuel cell powered vehicle requires a plentiful supply of clean hydrogen to achieve good performance. This can be made available via an on-board methanol reformer. Before the reformer reaches operating temperature it is necessary to obtain energy from an alternative source, such as a battery, in order to power the vehicle. This paper introduces a dynamic model of a methanol reformer fuel cell powered vehicle. The vehicle model is driven over the FTP drive cycle, from a cold start, using various warm up strategies. In this way, different strategies are evaluated in terms of performance and fuel efficiency.