Wyniki wyszukiwania - BazTech

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Simulation evaluation of the influence of selected geometric parameters on the operation of the pneumatic braking system of a trailer with a differential valve

Szpica Dariusz, Kisiel Marcin, Czaban Jarosław

Acta Mechanica et Automatica

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2022

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Vol. 16, no. 3

233--241

EN

This article presents simulation models of trailer air brake systems in configurations without a valve and with a differential valve, thus demonstrating the rationale for using a valve to improve system performance. Simplified mathematical models using the lumped method for systems without and with a differential valve are presented. The proposed valve can have two states of operation depending on the configuration of relevant parameters. These parameters can include the length of the control pipe, the throughput between chambers in the control part of the valve and the forcing rise time. Based on the calculations, it was found that the differential valve with large control pipe lengths can reduce the response time of the actuator by 42.77% relative to the system without the valve. In the case of transition of the valve to the tracking action, this time increases only by 9.93%. A force rise time of 0.5 s causes the transition of the valve from the accelerating action to the tracking action, with 9.23% delay relative to the system without a valve. The calculations can be used in the preliminary assessment of the speed of operation of pneumatic braking systems and in the formulation of guidelines for the construction of a prototypical differential valve. In conclusion, it is suggested to use a mechatronic system enabling smooth adjustment of the flow rate between chambers of the control system of the differential valve.

2

A review of compressed air engine in the vehicle propulsion system

Korbut Michal, Szpica Dariusz

Acta Mechanica et Automatica

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2021

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Vol. 15, no. 4

215--226

EN

Engines powered by compressed air as a source of propulsion are known for many years. Nevertheless, this type of drive is not commonly used. The main reason for not using commonly is the problem with the low energy density of the compressed air. They offer a number of advantages, primarily focusing on the possibility of significantly lowering the emissions of the engine. Their emissivity mainly depends on the method of obtaining compressed air. This also has an impact on the economic aspects of the drive. Currently there are only a few, ready to implement, compressed air powered engine solutions available on the market. A major advantage is the ability to convert internal combustion engines to run with compressed air. The study provides a literature review of solutions, focusing on a multifaceted analysis of pneumatic drives. Increasing vehicle approval requirements relating to their emissions performance are encouraging for the search of alternative power sources. This creates an opportunity for the development of unpopular propulsion systems, including pneumatic engines. Analysing the works of some researchers, it is possible to notice a significant increase in the efficiency of the drive, which may contribute to its popularisation.

3

Modelling of the low-pressure gas injector operation

Szpica Dariusz, Kusznier Michał

Acta Mechanica et Automatica

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2020

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Vol. 14, no. 1

29--35

EN

In recent years, there has been a growing interest in alternative sources of power supply for internal combustion engines. Lique-fied petroleum gas injection systems are among the most popular. It becomes necessary to know mathematical descriptions of the opera-tion 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 equa-tion 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 descrip-tion and determined in the course of opening and closing time calculations were related to the values declared by the manufacturer, show-ing differences below 3%. The presented mathematical model can be modified for other injector design solutions.

4

Evaluation of the influence of the supply pressure on functional parameters of the impulse low-pressure gas-phase injector

Szpica Dariusz, Borawski Andrzej, Mieczkowski Grzegorz, Kusznier Michał, Awad Mohamad M., Sadik Adel M., Sallah Mohammed

Acta Mechanica et Automatica

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2020

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Vol. 14, no. 4

180--185

EN

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.

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Modelling methodology of piston pneumatic air engine operation

Szpica Dariusz, Korbut Michal

Acta Mechanica et Automatica

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2019

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Vol. 13, no. 4

271--278

EN

The article presents a mathematical model describing the operation of a piston pneumatic air engine. Compressed air engines are an alternative to classic combustion solutions as they do not directly emit toxic exhaust components. In the study, a modified internal combustion piston engine was adopted as pneumatic engine. The mathematical model was divided on the two subsystems, that is, mechanical and pneumatic. The mechanical subsystem describes a transformation of compressed air supply process parameters to energy transferred to the piston and further the conversion of the translational to rotary motion; in turn, in the pneumatic part, the lumped elements method was used. Calculations were carried out using the Matlab-Simulink software, resulting in the characteristics of external and economic indicators. The presented mathematical model can be ultimately developed with additional elements, such as the intake or exhaust system, as well as timing system control.