In recent years, there has been a growing interest in alternative sources of power supply for internal combustion engines. Liquefied petroleum gas injection systems are among the most popular. It becomes necessary to know mathematical descriptions of the operation of individual components. The article presents a mathematical model that describes the operation of the low-pressure gas injector. Valtek plunger injector was chosen as the test object. The mathematical description includes three parts, i.e. electric, mechanical and pneumatic. The electrical part describes the generation of electromagnetic force by a circuit with a coil, in the mechanical equilibrium equation of forces acting on the plunger, and in the pneumatic part the air pressure on the plunger. The calculations were performed in the Matlab/Simulink environment, creating current waveforms, acting forces and plunger displacement. Correctness of mathematical description and determined in the course of opening and closing time calculations were related to the values declared by the manufacturer, showing differences below 3%. The presented mathematical model can be modified for other injector design solutions.
The article presents a model-based evaluation of the impact of the plunger stroke on functional parameters of the low-pressure pulse gas solenoid injector. A reduced-order physics-based mathematical model was used to achieve this goal. The model was built on the basis of specified simplifications of the process, considering the forces that cause the plunger to move and the forces constituting resistance to its displacement. The implementation of a mathematical description in to the Matlab-Simulink environment allowed one to determine the characteristic values of operation of the Valtek Rail Type-30 injector, including plunger displacement courses. Calculations made with the assumption of the factory plunger stroke confirmed the validity of the model. The differences in opening and closing times were below 3% in comparison to the values given in the objects technical information. By assuming a specific plunger stroke, the functional relationships of opening and closing times were determined. The results showed a distortion of the force–response dependence for different plunger strokes. Results presented in the article can be used to support control-oriented modeling of systems incorporating pulsed gas dosing devices, such as combustion engines or gas turbines. More specifically, the proposed method can be used to pre-calibrate the delay time of the injector operation.
The article presents research results referring to the influence of supply pressure on the functional parameters of the impulse low-pressure gas-phase injector. The study was done on the original stand for flow test of gas-phase injectors. In the indirect evaluation, with the initial parameters and the length of the forced impulse, the current line, acceleration and pressure sensor courses were used. Apart from the volumetric flow rate, the analysed parameters were the time periods of the injector opening and closing process. Those time segments were composed of response time and opening/closing time, the sum of which gives time of full opening. Functional relationships describing the volumetric flow rate, time of full opening and closing are presented, which are helpful not only in comparative tests of different injectors, but also in modelling the operation of gas injector or algorithms of gas supply control system. The reference to the volumetric flow rate allowed to indicate possible causes of variability of this parameter depending on the supply pressure.
In the paper, an attempt was made to computationally demonstrate the effect of the plunger pressure stiffness on the opening and closing times of the low-pressure gas-phase injector as a filling of the research gap in this subject. Based on the presented mathematical model describing the operation of the injector, firstly the results were related to the manufacturer's technical data showing a shorter time to full opening by 2.77% and a longer time to full closing by 0.50%. On this basis, it was considered that the proposed model can be used for comparison purposes. In the assumed range of compression spring stiffness (100... 2000) N/m, it was shown that as the stiffness increases, the time to fully open decreases by 18.85%, while the time to fully closed decreases by 80.17%. Additionally, it is shown that the time-cross section as the stiffness of the compression spring increases can decrease up to 35.21% from the initial value. The obtained results can be useful in modeling the operation of an internal combustion engine or in the operational assessment of the gas injector condition.
The increasing public awareness of the negative impact of harmful substances emitted as a result of the operation of vehicles powered by internal combustion engine on health and the environment has contributed to the dynamic development and popularization of alternative propulsion systems. The main development trend are electric drives; however, some manufacturers are looking for new solutions, among which the pneumatic drives can be distinguished. One of the advantages of this type of propulsion is the possibility of adapting currently used combustion engines to compressed air supply. The paper concentrates on presenting solutions applied by researchers to propulsion conversion, on the basis of which own concept is proposed. The modification process of a single-cylinder two-stroke engine for compressed air supply was described. The adaptation of the solenoid valve parameters as an actuator of the cylinder filling system was performed. This type of design allows for the start of the cylinder filling with compressed air at any time in relation to the crankshaft rotation angle. A functional diagram of the control process operation of the engine power system was developed which enables its correct operation. An important element of the system, in terms of the optimization of engine operation, was the opportunity to have an impact on selected power supply parameters. The purpose of this paper is to demonstrate the potential of utilizing existing components of an internal combustion engine to build a power unit, which does not require a combustion process to generate torque. The presented method of propulsion system conversion will allow for the popularization of compressed air supply system as an alternative propulsion source.
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