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The surface vibration signals are widely used since they have much combustion information. However, for an Internal Combustion Engine (ICE), the measured surface vibration signals are difficult to utilize because they contain non in-cylinder pressure excitation response. The vibration response signals excited by the in-cylinder pressure excitation (ICPE) and the reciprocating inertia force excitation (RIFE) are overlapped in both time and frequency domain. That means they cannot be separated effectively by conventional signal processing method. In this paper, a new strategy to extract ICPE response from measured vibration signals by pattern recognition method is proposed. A model is established to describe the RIFE response. Then, the RIFE response could be predicted and subtracted directly from the measured vibration velocity signals. The processing results indicate that a fourth-order model and the data of initial compression stroke can reach satisfactory results.

Experiment is carried out on an engine dynamometer bench for simulating the cold-start of port-injected gasoline engines. Based on the measured temperatures and HC emissions at the inlet and outlet of the catalytic converter as well as cylinder pressure, how to achieve minimum catalytic-converter-out HC emissions prior to catalyst light-off has been discussed. In this experiment, the cold-start period is divided into three stages referred to the opening of the throttle valve. Most of the HC are emitted in the first stage, i.e. from cranking to the opening of the throttle valve. Retarding of spark timing could cause incomplete combustion in the cylinder and lead to the oxidization of the unburned HC in the exhaust manifold, which results in reductions of tail-pipe HC emissions. Incomplete combustion could also occur when throttle valve is open by setting proper spark timing.

In this paper, the authors proposed a method for on line rapid estimation of power performance and mechanical losses of engines. The power and mechanical losses of an engine are estimated based on the principle of inertia acceleration-deceleration and the measurement of transient crankshaft speed variation that were taken from the updated data acquisition processing measurement system. The calculation, feature and function of the on line rapid estimation methods are described. The derived power and mechanical losses using this method were compared to the results by dynamometer. The experimental equipment as well as the results are illustrated. Using this method, the characteristic mechanical efficiency of the engine as well as the cylinder's relative compression[1][2], starting and acceleration performance could also be estimated easily.

In this paper authors propose a new method for estimation of cylinder compression. Under motoring condition, when the transient rotational speed fluctuation of flywheel within a working cycle has been measured, the Max. compressive pressure of each cylinder were calculated based on the principle of inertia acceleration. The testing results of 4 and 6 cylinder engines show that, the measured errors were within ±3%, so it is a proper tool for fast estimation the compression of engine mounted on vehicles especially.