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There is a trend towards increasing the degree of engine downsizing due to its potential for reducing fuel consumption and hence lowering CO2 emissions. However, downsizing introduces significant challenges for the engine airpath hardware and control, if driveability is to be maintained at an acceptable level. The transient response of the engine is affected by both the hardware selection and the associated controller. In order to understand the potential performance and limitations of the possible airpath hardware, a mean value model of the engine under consideration can be utilized. One benefit of these models is that they can be used as the basis of a model predictive controller which gives close to optimal performance with minimal tuning effort. In this paper we examine different two-stage series sequential turbocharger arrangements.

The control of NOX emissions by exhaust gas recirculation (EGR) is of widespread application. However, despite dramatic improvements in all aspects of engine control, the subtle mixing processes that determine the cylinder-to-cylinder distribution of the recirculated gas often results in a mal-distribution that is still an issue for the engine designer and calibrator. In this paper we demonstrate the application of a relatively straightforward technique for the measurement of the absolute and relative dilution quantity in both steady state and transient operation. This was achieved by the use of oxygen sensors based on standard UEGO (universal exhaust gas oxygen) sensors but packaged so as to give good frequency response (∼ 10 ms time constant) and be completely insensitivity to the sample pressure and temperature. Measurements can be made at almost any location of interest, for example exhaust and inlet manifolds as well as EGR path(s), with virtually no flow disturbance.

Recent work has investigated the use of O₂ concentration in the intake manifold as a control variable for diesel engines. It has been recognized as a very good indicator of NOX emissions especially during transient operation, however, much of the work is concentrated on estimating the O₂ concentration as opposed to measuring it. This work investigates Universal Exhaust Gas Oxygen (UEGO) sensors and their potential to be used for such measurements. In previous work it was shown that these sensors can be operated in a controlled pressure environment such that their response time is of the order 10 ms. In this paper, it is shown how the key causes of variation (and therefore potential sources of error) in sensor output, namely, pressure and temperature are largely mitigated by operating the sensors in such an environment. Experiments were undertaken on a representative light-duty diesel engine using modified UEGO sensors in the intake and exhaust system.

A key challenge in achieving good transient performance of highly boosted engines is the difficulty of accelerating the turbocharger from low air flow conditions (“turbo lag”). Multi-stage turbocharging, electric turbocharger assistance, electric compressors and hybrid powertrains are helpful in the mitigation of this deficit, but these technologies add significant cost and integration effort. Air-assist systems have the potential to be more cost-effective. Injecting compressed air into the intake manifold has received considerable attention, but the performance improvement offered by this concept is severely constrained by the compressor surge limit. The literature describes many schemes for generating the compressed gas, often involving significant mechanical complexity and/or cost. In this paper we demonstrate a novel exhaust assist system in which a reservoir is charged during braking.

This paper presents an experimental calibration method for the feedforward fuelling controller for a PFI SI engine. A recently proposed method [1] is extended from the idle to the torque delivery region and uses a Riccati designed rather than Parameter-Space linear element. Dynamic input signals are applied to air path, load and fuel entering the engine to excite the air-to-fuel ratio dynamics. A nonlinear inverse compensator is obtained directly from the observed input-output behaviour. Least squares black-box identification is used to generate the compensator using an algebraic NARX structure. The resulting inverse compensator not only acts as the feedforward controller but also linearises the fuelling path and therefore makes the system well suited for robust linear feedback control. The feedforward compensator is experimentally demonstrated and subsequently a robust H-infinity feedback controller is designed, implemented and the complete system experimentally validated.

The ion current sensing technique is used in this paper with available engine signals (engine speed, N, and manifold absolute pressure, MAP) to train neural networks (NN) to estimate the peak pressure position (PPP) across four cylinders of a spark ignition internal combustion engine. The stochastic nature across these four cylinders is evident; the variability in the PPP is a highly useful measure of cycle to cycle variation (CCV) of combustion since it may be determined directly and so can be used in feedback control. After experimental implementation on the engine, it is seen that the technique gives reliable PPP estimation for control feedback. In addition the PPP is known to correlate well with spark advance (SA) for maximum best torque (MBT) [1]. A constrained variance (CV) control technique is a solution to reducing the variability in the PPP and so feedback is implemented to control the SA.

An identification based approach to the design and implementation of a Kalman-filter feedback control method for the transient chassis dynamometer is presented. The requirements for torque controllers for high speed transient chassis dynamometers for road-load simulation are discussed. A common significant problem with feedback control in the conventional transient chassis dynamometer is due to resonances arising from the structural dynamics especially in the load centre linkage. A Kalman filter based filter and control method is proposed to address this issue and to provide significantly enhanced performance over that achieved by current controllers. Particular attention is paid to obtaining relative stability margins in all filter and control loops for robust torque feedback control by the use of H-infinity methods. The filter and controller designs are based on easily implementable identification methods.

A direct comparison of engine performance and stability is made between two different systems for igniting gasoline and air mixtures in an internal combustion (IC) engine. A conventional spark ignition (SI) coil and electrical plug setup is compared to a laser ignition (LI) system, comprising of two Q-switched Nd:YAG lasers and a series of mirrors and lenses. The lasers were operated in single-mode at the fundamental wavelength of 1064 nm and were successfully used to ignite air-fuel mixtures in all four cylinders from engine start-up without misfires. The test engine used was an unmodified four cylinder 1.6 litre port fuel injection (PFI) production engine. Both ignition systems were triggered twice per engine cycle with one redundant spark on the exhaust stroke and the second spark on the compression stroke to ignite the air-fuel mixture.