Continuous compressor recirculation to improve boost response and mitigate compressor surge in turbocharged gasoline engines

Turbocharged engines are typically equipped with wastegates to control boost pressure, and compressor recirculation valves (CRVs) to prevent compressor surge. For cost reasons, CRVs are typically simple on/off devices. We replace the on/off CRV with a Continuously-variable Compressor Recirculation Valve (CCRV). Because it is continuous, this device can be used, in coordination with the wastegate, to improve the boost response. It can also be used to effectively and robustly prevent compressor surge on both aggressive and mild tip-outs, and to steer compressor operation away from undesirable regions during tip-ins. In this paper, we describe the requirements and design of the CCRV control system, and present vehicle results demonstrating the efficacy of this device.