A new knock event definition for knock detection and control optimization

Bares, Pau; Selmanaj, Donald; Guardiola, Carlos; Onder, Christopher H.

doi:10.1016/j.applthermaleng.2017.11.138

Cited by 53 publications

(29 citation statements)

References 38 publications

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“…A large amount of knock studies have been carried out on knock occurrence prediction [6][7][8][9][10], knock suppression [11][12][13], and knock generation mechanism study [14][15][16]. However, because of the random nature led by engine cycle-to-cycle variations and some other unobservable effects such as the unburned end-gas mass or hot spot temperature gradient [17][18][19], the knock phenomenon is randomly observed from cycle to cycle. Thereby, it is time and energy consuming to obtain the statistical data of knock behavior.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Knock Mechanism with Multiple Spark Plugs and Multiple Pressure Sensors

Shi¹,

Uddeen²,

An³

et al. 2020

SAE Technical Paper Series

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Engine knock is an abnormal phenomenon, which places barriers for modern Spark-Ignition (SI) engines to achieve higher thermal efficiency and better performance. In order to trigger more controllable knock events for study while keeping the knock intensity at restricted range, various spark strategies (e.g. spark timing, spark number, spark location) are applied to investigate on their influences on knock combustion characteristics and pressure oscillations. The experiment is implemented on a modified single cylinder Compression-Ignition (CI) engine operated at SI mode with port fuel injection (PFI). A specialized liner with 4 side spark plugs and 4 pressure sensors is used to generate various flame propagation processes, which leads to different auto-ignition onsets and knock development. Based on multiple channels of pressure signals, a bandpass filter is applied to obtain the pressure oscillations with respect to different spark strategies. Finally, the relationships among in-cylinder pressure, knock intensity, pressure fluctuation, heat release and measurement location, are analyzed to get better understanding on knock mechanism, influence factors and measurement methods. The main results show that: Igniting two spark plugs simultaneously brings higher knock amplitude than single spark ignition, however, adding more spark sites could effectively suppress the knock strength and rate of recurrence. A function (Y =-0.25X + 2.82) is fitted to illustrate the relations between the crank angle of 1st peak of knock oscillation and MAPO. Besides, the correlations among MAPO and other influential factors are evaluated. Moreover, the pressure sensors installed around the liner give different pressure fluctuations, which indicate the directionality of pressure wave transmission in cylinder during knock process.

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Section: Introductionmentioning

confidence: 99%

Experimental Study on Knock Mechanism with Multiple Spark Plugs and Multiple Pressure Sensors

Shi¹,

Uddeen²,

An³

et al. 2020

SAE Technical Paper Series

View full text Add to dashboard Cite

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“…Any other method capable of detecting knock occurrence (not its intensity) can be alternatively used, e.g. [4], [25].…”

Section: Stochastic Knock Modellingmentioning

confidence: 99%

Adaptive and Unconventional Strategies for Engine Knock Control

Selmanaj

Panzani

Dooren

et al. 2019

IEEE Trans. Contr. Syst. Technol.

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Knock is an undesirable phenomenon affecting gasoline spark-ignition (SI) engines. In order to maximize engine efficiency and output torque while limiting the knock rate, the spark timing should be adequately controlled. This paper focuses on closed-loop knock control strategies. The proposed control strategies, compared to conventional approaches, show improved performances while remaining simple to use, implement, and tune. Firstly, a deterministic controller which employs a logarithmic increase of the spark timing proves to outperform the conventional strategy in terms of spark timing average and variance. In addition, an adaptive parameter strategy which exploits stochastic information of the process is introduced. Thanks to this extension the average and the variance of the spark timing are additionally improved while preserving ease of tuning and the fast reaction times of the deterministic strategy. Throughout the paper all the knock controllers are compared with a conventional deterministic strategy and with a recently proposed stochastic one. The advantages of the proposed approaches are confirmed both by simulation and by experimental data collected at a test bench.

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“…Knock was detected by analysing the frequency content of the in-cylinder pressure signal such as in [38]. This methodology does detect low-knocking cycles by comparing the resonance excitation near the maximum heat release rate (normal combustion) and next to the maximum unburned temperature (autoignition).…”

Section: Experimental Set-upmentioning

confidence: 99%

Knock probability estimation through an in-cylinder temperature model with exogenous noise

Bares

Selmanaj

Guardiola

et al. 2018

Mechanical Systems and Signal Processing

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This paper presents a new knock model which combines a deterministic knock model based on the in-cylinder temperature and an exogenous noise disturbing this temperature. The autoignition of the end-gas is modelled by an Arrhenius-like function and the knock probability is estimated by propagating a virtual error probability distribution. Results show that the random nature of knock can be explained by uncertainties at the in-cylinder temperature estimation. The model only has one parameter for calibration and thus can be easily adapted online. In order to reduce the measurement uncertainties associated with the air mass flow sensor, the trapped mass is derived from the in-cylinder pressure resonance, which improves the knock probability estimation and reduces the number of sensors needed for the model. A four stroke SI engine was used for model validation. By varying the intake temperature, the engine speed, the injected fuel mass, and the spark advance, specific tests were conducted, which furnished data with various knock intensities and probabilities. The new model is able to predict the knock probability within a sufficient range at various operating conditions. The trapped mass obtained by the acoustical model was compared in steady conditions by using a fuel balance and a lambda sensor and differences below 1% were found.

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A new knock event definition for knock detection and control optimization

Cited by 53 publications

References 38 publications

Experimental Study on Knock Mechanism with Multiple Spark Plugs and Multiple Pressure Sensors

Experimental Study on Knock Mechanism with Multiple Spark Plugs and Multiple Pressure Sensors

Adaptive and Unconventional Strategies for Engine Knock Control

Knock probability estimation through an in-cylinder temperature model with exogenous noise

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