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The pump-pipe-injector-injection system is the most commonly used type of injection equipment for Diesel engines. In order to be compatible with digital engine control, this system needs to be modified. The resulting fuel injection system should have the following characteristics: mechanical simplicity, direct control capability and low cost. Based on these requirements, the direct digital control of the pump-pipe-injector injection system has been investigated. A new solenoid control valve has been designed to simultaneously control the injection timing, fuel quantity and hydraulic performance. The conventional jerk-pump is very much simplified. A research type control unit based on a PC has been developed. The system has the possible configuration of electronic pump-pipe-valve-injector and electronic pump-valve-pipe-injector. The system was designed and analyzed on the basis of a comprehensive mechanical - magnetic - electrical - hydraulic computer simulation of the system.

A mean value model is presented for the transient operation of a 1.6 liter turbocharged indirect injection diesel engine. The model consists of a series of sub-models for the compressor, turbine and engine which result in a number of coupled, non-linear algebraic and differential equations. The equations are solved using a standard numerical solution package on a personal computer. The initial model calibration was performed using manufacturer supplied data and experimental data from steady state operation. Additional refinements of the model and its associated parameters were obtained through comparison with dynamic measurements on the engine. A comparison between simulated and experimental performance parameters is presented for both steady state and dynamic operation.

The new generation of electronic Diesel fuel injection systems with special solenoid valves presents a complicated mechanical/electrical system. It involves a combination of mechanical motion, hydraulic pressure wave propagation, and the transient magnetic and electrical processes which interact with other. In this paper, the coupled dynamic behavior of the new system is studied based on a research type electronic pump-pipe-injector system developed by authors. A general physical model is established, which includes other structure types such as the electronic unit injector and the electronic distributor pump system. Traditional mathematical models for conventional mechanical injection system or conventional solenoid valves, alone or simply connected, are not suitable for the new type of injection system. Therefore, a new comprehensive mathematical model is formulated.

An experimental study is presented in which the use of neat dimethyl ether (DME) in a small non-turbo-charged diesel engine is demonstrated. It was found that with only minor fuel system modifications, DME gave very satisfactory combustion, performance and emissions. Engine operation with thermal efficiency equivalent to diesel fuel was achieved with much lower NOx emissions and with extremely low smoke and less engine noise. Additional NO, reductions were obtained by the use of EGR, without visible smoke and without deterioration in thermal efficiency, A limited durability study showed that the diesel fuel injection pump could operate on DME for more than 500 hours. A comparison of pure and technical grade DME was conducted.