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Low Pressure Cooled Exhaust Gas Recirculation (LP EGR) is an attractive technology to reduce fuel consumption for a spark-ignition (SI) engine, particularly at medium-to-high load conditions, due to its knock suppression and combustion cooling effects. However, the long LP EGR transport path presents a significant challenge to the transient control of LP EGR for the engine management system. With a turbocharged engine, this is especially challenging due to the much longer intake induction system path compared with a naturally aspirated engine. Characterizing and modeling the EGR, intake air mixing and transport delay behavior is important for proper control. The model of the intake air path includes the compressor, intercooler and intake plenum. It is important to estimate and track the final EGR concentration at the intake plenum location, as it plays a key role in combustion control. This paper describes the development of a real-time, implementable model for LP EGR estimation.

Low-pressure, Cooled Exhaust Gas Recirculation (LPC EGR) brings significant fuel economy, NOx reduction and knock suppression benefits to a modern, boosted, downsized Spark Ignition (SI) engine. As a prerequisite to design an engine control system for LPC EGR, this paper presents development of a set of estimation algorithms to accurately estimate the flow rate, pressure states and thermal states of the LPC EGR-related components.

This paper first presents a basic mean value engine plant model implemented in a hardware-in-the-loop (HIL) system. The plant model includes some basic engine parameters such as engine speed, manifold absolute pressure, etc., which are critical to both control algorithm integrity and default actions that result from improper signal performance (e.g., ECU shuts down due to corrupted signal(s)). The model is then improved to develop the HIL bench-based testing capabilities in the areas where a vehicle has traditionally been required. The on-board diagnostic monitor tests covered by SID $06 of SAE J1979 are selected as a case study. Specifically, for OBD exhaust gas sensor monitor testing purposes, the oxygen sensor model is developed to simulate normal or abnormal binary switching signals which might have asymmetric “lean to rich” and “rich to lean” transitions, or largely off maximum/minimum sensor voltages, etc.

Intake camshaft retard beyond that necessary for reliable cold start-ability is shown to improve part-load fuel economy. By retarding the intake camshaft timing, engine pumping losses can be reduced and fuel economy significantly improved. At high engine speeds, additional intake cam retard may also improve full-load torque and power. To achieve these benefits, an intake camshaft phaser with intermediate lock pin position (ILP) and increased phaser authority was developed. ILP is necessary to reliably start at the intermediate phase position for cold temperatures, while providing increased phaser retard under warm conditions. The phaser also provides sufficient intake advance to maximize low-speed torque and provides good scavenging for boosted engine applications. Design and development of the intermediate locking phaser system is described. The pros and cons of various methods of accomplishing locking and unlocking a phaser are illustrated.

This paper describes an enhanced application of variable cam timing (VCT) systems for improved conservation of energy and phase rate performance at high temperature and low RPM conditions. This virtual check valve control is demonstrated to provide faster phase rate at high temperature and low RPM conditions than either conventional VCT systems, or those using mechanical check valves. It offers expanded temperature and RPM operating range and further removes VCT systems from imposing burden on fuel-economy-sensitive oil pump systems. The virtual check valve concept is demonstrated in simulation. An ECU control is implemented and tested on a V6 engine.

Signal processing incorporating Artificial Neural Networks (ANN) has been shown to be well suited for modeling engine-related performance indicators [ 1 , 2 , 3 ] that require multi-dimensional parametric calibration space. However, to obtain acceptable accuracy, traditional ANN implementation may require processing resources beyond the capability of current engine controllers. This paper explores the practicality of implementing an ANN-based algorithm performing real-time calculations of the volumetric efficiency (VE) for an engine with variable valve actuation (phasing and lift variation). This alternative approach was considered attractive since the additional degree of freedom introduced by variable lift would be cumbersome to add to the traditional multi-dimensional table-based representation of VE.

This paper describes the verification and comparison of position control algorithms for a continuously-variable cam phaser. Robust Engineering techniques are used. Two non-linear PID control algorithms are designed to control cam phaser position. The first algorithm is a more complex control strategy while the second is a thrifted approach that seeks to reduce throughput requirements. An L18 orthogonal array is established with noise factors that affect the quality of cam phaser control. Using the orthogonal array, the number of experiment test points required to characterize the control algorithm response is reduced from 8,748 to thirty-six. The test points of the orthogonal array are investigated experimentally on a motored engine outfitted with cam phaser hardware. The desired and actual cam position data are compared and analyzed for all points in the orthogonal array.

Simultaneous control of speed and air-fuel ratio in a six-cylinder automobile engine is studied. A three-state engine model including rotational, air intake and fuel intake dynamics is used for control design. Control design focuses on application of nonlinear control techniques, specifically sliding mode control. Controllers are designed for tracking speed profiles and regulating air-fuel mixture. Multiple-surface sliding control is shown to result in good speed tracking in simulation and experiment. The production fuel controller and an observer-based sliding controller are shown to result in the best fuel control during speed transients. A standard sliding fuel controller is shown to result in high amplitude deviations due to oxygen sensor time delay. The best combination of controllers is shown to be the multiple-surface sliding speed controller and the observer-based fuel controller.