Torque ratio concept for combustion phasing detection of a spark ignited engine
This paper presents a method for estimating combustion phasing of a five cylinder, four stroke, spark ignited engine, equipped with a crankshaft based torque sensor. A new measure for combustion phasing based on the torque signal is derived for a single cylinder engine. The measure is called 50% torque ratio. A validation of the measure is done by comparing to the related cylinder pressure based 50% pressure ratio measure. A method is also presented to apply the torque ratio measure to a multi-cylinder engine. A physical model for the instantaneous torque measurement is described handling the torque contributions from all individual cylinders in all combustion phases. The torque contribution from the combusting cylinder is isolated and analyzed by the torque ratio method to find the combustion phasing. The multi-cylinder algorithm is validated on torque and cylinder pressure data from a five cylinder Volvo V70 engine.
Torque estimation based on nonlinear engine model considering crankshaft torsion
This paper discusses a torque estimation method for combustion engines by utilizing nonlinear modeling. In the proposed method a precise nonlinear engine model is described, and is used to estimate the engine torque based on a crankshaft angle. Especially the torsional effect of the crankshaft is considered in the proposed framework to improve the estimation accuracy. The model requires derivatives of the crankshaft angle, and a high-gain observer plays an important role to differentiate the angle. The proposed method with the precise engine model is verified through some numerical simulations. The simulation results show that the method can improve the torque estimation even with unignorable crankshaft torsion.
Carbon Dioxide Elimination from Circle Systems
Ten various circle systems were studied in model experiments. All the experiments were performed using a Waters cannister containing 675–685 g of Durasorbr̀. 300 ml of carbon dioxide were supplied to the system per min. The efficacy of these systems was expressed as the time taken to demonstrate a concentration of 0.6% carbon dioxide in the gas mixture supplied to the patient connection during each respiratory cycle. The carbon dioxide elimination was studied at a gas flow of 2, 4 and 6 1 per min. All the systems showed an effective carbon dioxide elimination for 6 h or more at a flow of 2 1. An increasing efficacy was found with increasing flow, but to a varying extent.