Compressor Surge Mitigation in Turbocharged Spark-Ignition Engines without an Anti-Surge Control System during Load-Decrease Operation

José Galindo,David González-Domínguez,Joaquín De La Morena,Héctor Climent,Stéphane Guilain,Thomas Besançon

doi:10.3390/app12031751

José Galindo, David González-Domínguez + Show 4 more

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https://doi.org/10.3390/app12031751

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Abstract

Automotive manufacturers are showing an increasing preference for hybrid powertrains based on advanced gasoline engines. The most extended solution to improve fuel economy in these engines consists in downsizing with direct injection, while turbocharging is required to compensate the consequent power loss. However, turbocharging is associated with different issues, such as compressor surge. It can appear during fast throttle closings (tip-outs), when the engine air flow is abruptly reduced. A usual strategy to manage this kind of maneuver is the installation of an anti-surge valve (ASV) that connects the compressor inlet and outlet when approaching the surge limit. In pursuit of cost reduction, the removal of the ASV system was assessed in this research. To this end, tip-outs without ASV were tested in a turbocharged gasoline engine equipped with a low-pressure EGR loop, and two strategies were analyzed: throttle closure optimization and reduction of the compressor inlet pressure through the intake flap (located upstream of the compressor to increase the EGR rate). The instantaneous compressor outlet pressure and its time derivative were used for surge detection. Experimental tip-outs without ASV revealed that applying a certain intake flap closing combined with an optimized throttle actuation led to a fast torque decrease, similar to that observed for the reference case with ASV, without compressor instabilities.

Highlights

In search of greener transport solutions, hybrid powertrains based on advanced sparkignition (SI) engines, usually fueled with gasoline, have become one of the most common propulsion systems in new passenger cars
Other interesting strategies are being applied to gasoline engines to improve fuel economy, such as exhaust gas recirculation (EGR), variable valve timing [6], deactivation of cylinders [7], and water injection in the intake ports [8]
The experimental results of the tip-out maneuvers at 1500 rpm from full to zero load without antisurge valve (ASV) were arranged into two subsections: (i) optimization of throttle actuation to operate as close as possible to the surge limit and (ii) assessment of the effect of different intake flap closings on the surge margin to reduce maneuver duration

Summary

Introduction

In search of greener transport solutions, hybrid powertrains based on advanced sparkignition (SI) engines, usually fueled with gasoline, have become one of the most common propulsion systems in new passenger cars. This solution is successful due to the reduction of SI engine operation at low load conditions [1,2], and to the lower complexity of the three-way catalyst compared to diesel aftertreatment devices [3]. Luján et al [9] and Siokos et al [10] demonstrated that introducing cooled EGR leads to a lower knock tendency and allows removing fuel enrichment to control the turbine inlet temperature. Some improvements have been studied to compensate the turbocharger lag, such as the application of low-viscosity oils [11], advanced bearing technologies [12], mechanically driven superchargers [13], electric boosters [14], and VGT control strategy optimization [15,16]

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