Steve Magner

Cylinder air-charge estimation for advanced intake valve operation in variable cam timing engines

Abstract High efficiency of three-way automotive catalysts is achieved by regulating cylinder air–fuel ratio in a narrow band around the stoichiometry. Due to a delay present in the exhaust gas oxygen sensor signal, performance of the air–fuel ratio regulation depends on accuracy of the cylinder air-charge estimate. Variable cam timing (VCT) introduces a challenge to the air-charge estimator due to its effect on engine pumping and, in some cases, due to unmeasured back-flow of the exhaust gas into the intake manifold. The objective of this paper is to illuminate some of these issues and suggest methods to improve accuracy of air-charge estimation in VCT engines.

Transient effects and torque control of engines with variable cam timing

A dual-equal variable cam timing (VCT) system implemented in an SI automotive engine improves performance in terms of emissions, fuel economy, peak torque, and peak power. A drawback of the technology is a deterioration in transient response of the engine that may affect vehicle drivability. Several methods to improve transient performance of a VCT engine have been proposed in the literature. The purpose of this paper is to report experimental testing results for a feedforward VCT controller proposed by Jankovic et. al. (1998). The paper also describes the hardware setup and addresses several issues relevant to controller implementation.

Towards ECU-Executable Control-Oriented Models of a Three-Way Catalytic Converter

The nonlinear dynamics of an automotive three-way catalyst (TWC) present a challenge to developing simple control-oriented models that are both useful for control and/or diagnostics and real-time executable within a vehicle engine-control unit (ECU). As such, we begin by developing a first-principles control-oriented TWC model and then proceed to apply simplifications. The TWC models are spatially discretized along the catalyst length to better understand and exploit the oxygen-storage dynamics. The TWC models also include the oxidation reaction of ceria by H2O, which is considered important since it represents the production of H2 within the catalyst. We present automated optimization routines to calibrate the TWC model along with a heated exhaust-gas oxygen (HEGO) sensor model using measured vehicle and emissions data. Finally, we demonstrate the combined models’ ability to accurately reproduce the measured HEGO voltage using engine feedgas constituent inputs, which is necessary for designing a robust model-based feedback controller.Copyright

Power output monitoring for vehicles equipped with electronic throttle

Vehicles equipped with electronic throttle control (ETC) systems are entering the automotive marketplace for several reasons, including improved fuel economy (early transmission upshifts, lean-burn combustion, variable displacement engines), drivability (improved pedal response, altitude compensation, traction control), and emissions (controlled tip-in/tip-out, cold start). These improvements come at the cost of increased complexity. One of the issues is related to engine power output detection and mitigation in case of operation under exceptional conditions. The authors propose a method that monitors the operation of the powertrain based on the amount of injected fuel and provides a natural mitigating action.

Mid-ranging control for an automotive three-way catalyst outer loop

As government regulations force stringent automobile emission standards with graceful degradation under various hardware faults and operating environments, accurate feedback control of the engine air-to-fuel ratio has become a key enabler. We present an overview of the automotive three-way catalyst (TWC) control system and discuss challenges associated with development and implementation of a successful feedback controller, including plant and sensor nonlinearities - in use, as well as regulatory On-Board-Diagnostics induced faults, bandwidth restrictions, and constraints such as drivability and noise, vibration, and harshness (NVH) considerations. To meet these goals, we modify the conventional mid-ranging control structure for accurate control of the TWC subsystem while simultaneously adhering to drivability and NVH constraints. Vehicle test results are shown exhibiting the controllers capabilities with and without induced faults.