Fuel Economy of a Multimode Combustion Engine With Three-Way Catalytic Converter

Nüesch, Sandro P.; Stefanopoulou, Anna G.; Jiang, Li; Sterniak, Jeff

doi:10.1115/1.4028885

Cited by 7 publications

(3 citation statements)

References 34 publications

(47 reference statements)

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“…AFR should be kept close to stoichiometric for catalyst efficiency. Any leaning that occurs should be small relative to the catalyst oxygen storage capacity, as filling of the oxygen storage may affect the allowable stay duration in HCCI [18]. The SI-HCCI switch point should be reached as quickly as possible for fast entry to HCCI.…”

Section: Cam Switching Spark Ignition-homogeneous Charge Compression mentioning

confidence: 99%

SI-HCCI Mode Transitions Without Open-Loop Sequence Scheduling: Control Architecture and Experimental Validation

Gorzelic

Stefanopoulou

Sterniak

2017

Journal of Dynamic Systems, Measurement, and Control

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This paper describes a model-based feedback control method to transition from spark ignition (SI) to homogeneous charge compression ignition (HCCI) combustion in gasoline engines. The purpose of the control structure is to improve robustness and reduce calibration complexity by incorporating feedback of the engine variables into nonlinear model-based calculations that inherently generalize across operating points. This type of structure is sought as an alternative to prior SI-HCCI transition approaches that involve open-loop calibration of input command sequences that must be scheduled by operating condition. The control architecture is designed for cam switching type SI-HCCI mode transition strategies with practical two-stage cam profile hardware, which previously have only been investigated in a purely open-loop framework. Experimental results on a prototype engine show that the control architecture is able to carry out SI-HCCI transitions across the HCCI load range at 2000 rpm engine speed while requiring variation of only one major set point and three minor set points with operating condition. These results suggest a noteworthy improvement in controller generality and ease of calibration relative to previous SI-HCCI transition approaches.

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Section: Cam Switching Spark Ignition-homogeneous Charge Compression mentioning

confidence: 99%

SI-HCCI Mode Transitions Without Open-Loop Sequence Scheduling: Control Architecture and Experimental Validation

Gorzelic

Stefanopoulou

Sterniak

2017

Journal of Dynamic Systems, Measurement, and Control

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“…A comparable analysis in another engine with multimode combustion can also be found in Gao et al 25 concerning reactivity controlled compression ignition (RCCI) and conventional diesel combustion. In Nu¨esch et al, 26 the interaction between SI/HCCI multimode engine and three-way catalyst was analyzed in terms of drive cycle fuel economy and NO x emissions. It was shown that the catalyst's oxygen storage fills up and requires depletion and hence rich operation.…”

Section: Introductionmentioning

confidence: 99%

Accounting for combustion mode switch dynamics and fuel penalties in drive cycle fuel economy

Nüesch

Gorzelic

Jiang

et al. 2015

International Journal of Engine Research

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A methodology is introduced to analyze the drive cycle fuel economy of a vehicle equipped with a multimode combustion engine, utilizing commercial cam phasers and two-step cam profile switching. The analysis is based on a longitudinal vehicle model with manual transmission. The engine model employs a finite state machine describing mode switches between two distinct combustion modes, namely, spark-ignited and homogeneous charge compression ignition. Preliminary combustion mode switch experiments were used to parameterize the model. The influence of mode switch fuel penalties on drive cycle fuel economy was quantified through application of the model to the federal test procedure (FTP-75), the highway fuel economy test (HWFET) and the US06 supplemental federal test procedure. The mode switches were analyzed individually in terms of their benefit on fuel economy and a distinction was made between harmful and beneficial mode switches. Mode switches were defined as harmful whether their fuel penalty is greater than the benefits originating from spending time in the subsequent homogeneous charge compression ignition mode. A parametric study was conducted to investigate the impact of harmful mode switches on fuel economy as a function of the fuel penalties during the switch. In the case of high fuel penalties, supervisory control becomes an important tool for minimizing the number of harmful mode switches. One possible supervisory strategy discussed is a smoothing strategy, in which a mode switch is delayed by introducing a dwell time.

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“…the feasible HCCI operating regime being an actual residence in HCCI combustion mode. Both [1,4] switch combustion modes based on the state of the three-way catalyst, thereby taking into account its temperature [1] and oxygen storage level [4]. The integration of a multimode combustion in a hybrid electric vehicle is discussed in [5,6] with a focus on the power and torque split decisions.…”

Section: Introductionmentioning

confidence: 99%

Is it Economical to Ignore the Driver? A Case Study on Multimode Combustion

Nüesch

Stefanopoulou

2015

Volume 1: Adaptive and Intelligent Systems Control; Advances in Control Design Methods; Advances in Non-Linear and Optimal Cont

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Ignoring the driver's torque command can be beneficial for fuel economy, especially if it leads to extended residence time at efficient operating conditions. We answered this question for a particular engine, which allows mode switches between spark ignition (SI) and homogeneous charge compression ignition (HCCI) combustion. When operating such a multimode combustion engine it might be required to defer a load command outside the feasible regime of one combustion mode until a mode switch is accomplished. The resulting delays in engine torque response might negatively affect vehicle performance and drivability. In this paper a longitudinal vehicle model is presented, which incorporates dynamics associated with SI/HCCI mode switching. Two exemplary supervisory control strategies were evaluated in terms of fuel economy and torque behavior. It was seen that the duration of a mode switch may be short enough to avoid substantial impairment in torque response. This in turn would lead to the opportunity of purposefully ignoring the driver command. Thereby, the residence time in the beneficial HCCI combustion regime is prolonged and fuel-expensive mode switching avoided. The result is a trade-off between torque deviation and improvements in fuel economy. Finally, based on this trade-off the supervisory control strategy relying on a short-term prediction of engine load was seen to achieve similar fuel economy with slightly improved torque response than a strategy without prediction.

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Fuel Economy of a Multimode Combustion Engine With Three-Way Catalytic Converter

Cited by 7 publications

References 34 publications

SI-HCCI Mode Transitions Without Open-Loop Sequence Scheduling: Control Architecture and Experimental Validation

SI-HCCI Mode Transitions Without Open-Loop Sequence Scheduling: Control Architecture and Experimental Validation

Accounting for combustion mode switch dynamics and fuel penalties in drive cycle fuel economy

Is it Economical to Ignore the Driver? A Case Study on Multimode Combustion

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