In traditional non-torque-based engine control systems, the operator directly dictates throttle position, usually via a direct mechanical connection such as a cable or linkage. The control system then applies combustion parameters, such as fuel and spark, based on the measured or calculated airflow. In a torque-based control system, the control unit receives a torque request, either directly from the operator or from elsewhere within a distributed powertrain management system. The control system then manages all combustion related parameters, including airflow via an electronic throttle actuator, to produce the requested torque - ideally maximizing thermal efficiency while, observing all emissions and drivability constraints. Torque-based engine management systems are much more conducive to integration within a comprehensive powertrain management system, and further, are all but required for control of contemporary engine technologies such as VVT, VGT, etc. This paper proposes a feed-forward, model-based control algorithm that calculates the throttle position needed to achieve the required airflow, or more precisely air charge mass. The larger torque-based control system, in which this throttle positioning algorithm resides, receives a torque request, either directly from the operator or from elsewhere within the powertrain control system, and then applies requested air mass, fuel mass, spark and other applicable combustion parameters to produce the requested torque. Making use of speed-density and compressible flow relationships, a throttle angle request is calculated, which produces the desired airflow and ultimately engine torque output. This throttle positioning algorithm is designed in a modular fashion so that torque-based and non-torque-based engine management systems can share base combustion calibrations and is adaptive to assure that engine variation and ageing effects are properly compensated for. The proposed torque control method was tested on a Harley-Davidson Experimental 'Twin Cam 96TM' engine equipped with an electronic throttle. It was shown to provide precise control of engine torque output during both transient and steady-state operation, and under varying ambient conditions.
Torque-based throttle positioning control strategy
IAV Symposium Steuerungssysteme für den Antriebsstrang von Kraftfahrzeugen, 6 ; 223-Folienbeitrag
2007
22 Seiten, 3 Bilder, 1 Quelle
Folienbeitrag
Aufsatz (Konferenz)
Englisch
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