The Lean Burn Control for LPG Engine Using Torque Estimation

Because of exhaust emission and fuel consumption request, ECU of modern gas engines usually use lean burn control techniques. Most of the engine lean burn control systems are based on linear oxygen sensor to measure air/fuel ratio. In this paper, a low-cost torque estimation for LPG engine control system has been developed. Lambda oxygen sensor is used instead of linear oxygen sensor. Algorithms suitable for real-time computation are employed for engine indicated torque estimation. The indicated torque is used as feedback variable for electronic throttle valve control, and used as feedforward compensation for fuel control. Although there is no linear oxygen sensor to measure air/fuel ratio, the LPG engines can be controlled to stable lean burn state, and satisfy output power, less fuel consumption and lower emission requirement simultaneously.