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Camshafts

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Anna G. Stefanopoulou – 1st expert on this subject based on the ideXlab platform

  • Air charge control for turbocharged spark ignition engines with internal exhaust gas recirculation
    Proceedings of the 2010 American Control Conference, 2010
    Co-Authors: Li Jiang, Hakan Yilmaz, Anna G. Stefanopoulou

    Abstract:

    This paper presents the design of transient cylinder charge control, based on a cycle-averaged mean-value model for a turbocharged spark ignition direct injection engine equipped with dual-independent intake and exhaust variable Camshafts which in this paper has been constrained to variable valve overlap with symmetric cam motions. The control-oriented model, parameterized using dynamometer measurements, is shown to capture engine static and dynamic behavior of throttled conditions. The transient effects of throttling and variable valve timing on the cylinder charge over part-load and lightly boosted conditions are first analyzed to investigate the dynamic interactions between the electronic throttle and the valve overlap through variable Camshafts. Given the fast dynamics of the electronic throttle actuator, a nonlinear feedforward and feedback throttle compensator, in reference to its static set-points, is employed here to improve the transient response of cylinder charge. It has been shown in simulation results that the combined use of both compensators can considerably improve transient engine performance.

  • Variable camshaft timing engine control
    IEEE Transactions on Control Systems Technology, 2000
    Co-Authors: Anna G. Stefanopoulou, J.s. Freudenberg, J.w. Grizzle

    Abstract:

    Retarding camshaft timing in an engine equipped with a dual equal camshaft timing phaser reduces the unburned hydrocarbons (HC) and oxides of nitrogen (NO/sub x/) emitted to the exhaust system. Apart from this positive effect to feedgas emissions, camshaft timing can cause large air-to-fuel ratio excursions if not coordinated with the fuel command. Large air-to-fuel ratio excursions can reduce the catalytic converter efficiency and effectively cancel the benefits of camshaft timing. The interaction between the camshaft timing and the air-to-fuel ratio results in an inherent tradeoff between reducing feedgas emissions and maintaining high catalytic converter efficiency. By designing and analyzing a decentralized and a multivariable controller, we describe the design limitation associated with the decentralized controller architecture and we demonstrate the mechanism by which the multivariable controller alleviates the limitation.

  • Analysis and control of transient torque response in engines with internal exhaust gas recirculation
    IEEE Transactions on Control Systems Technology, 1999
    Co-Authors: Anna G. Stefanopoulou, Ilya Kolmanovsky

    Abstract:

    We analyze the nonlinear dynamic behavior of an internal exhaust gas recirculation system based on a mean-value model of an experimental automotive engine equipped with a camshaft phaser. We develop a control scheme that adjusts camshaft timing to reduce feed-gas emissions while maintaining transient engine torque response similar to that of a conventional engine with zero exhaust gas recirculation. The control scheme consists of a feedforward map that specifies desired camshaft timing as a function of throttle position and engine speed in steady state, and a first-order lag that governs the transition of the camshaft timing to the desired value. The time constant of the first-order lag is adjusted based on engine speed and throttle position.

Ilya Kolmanovsky – 2nd expert on this subject based on the ideXlab platform

  • Analysis and control of transient torque response in engines with internal exhaust gas recirculation
    IEEE Transactions on Control Systems Technology, 1999
    Co-Authors: Anna G. Stefanopoulou, Ilya Kolmanovsky

    Abstract:

    We analyze the nonlinear dynamic behavior of an internal exhaust gas recirculation system based on a mean-value model of an experimental automotive engine equipped with a camshaft phaser. We develop a control scheme that adjusts camshaft timing to reduce feed-gas emissions while maintaining transient engine torque response similar to that of a conventional engine with zero exhaust gas recirculation. The control scheme consists of a feedforward map that specifies desired camshaft timing as a function of throttle position and engine speed in steady state, and a first-order lag that governs the transition of the camshaft timing to the desired value. The time constant of the first-order lag is adjusted based on engine speed and throttle position.

Liu Yongbing – 3rd expert on this subject based on the ideXlab platform

  • the study of cam materials and assembling technology of composite hollow Camshafts
    Materials Science and Technology, 2005
    Co-Authors: Liu Yongbing

    Abstract:

    The two key technique of composite hollow Camshafts were studied in this paper: cam materials and joining technique. Cam materials used ferrous P/M materials, and work surface were treated with wide-band laser surface quenching. After laser quenching, the wear resistance of cam materials were evidently improved. The joining of cam and core-shaft used shave-joining technique. The static joining strength and fatigue strength of Camshafts with different space between tooth were studied. The destroying torsion of Camshafts was 20 – 30 times as many as its actual work torsion, and its fatigue strength also met its work request.