Abstract
This paper presents a noninvasive method to obtain an extended diagram for a single cylinder four-strike cycle engine. In order to draw such a diagram we designed and built an experimental test bench. In the first part of this paper we described how one can make a piezoelectric pressure transducer that allows measuring the pressure within the internal combustion engine cylinder. We also drew the extended diagram for the single cylinder four-stroke engine using the aforementioned software. The diagrams that were obtained by means of experiment allow us to perform studies on how the motive fluid behaves inside the engine cylinder. This is achieved by studying the shape of the drawn curves, the process duration compared to the duration of the processes obtained by calculus, functionality anomalies or parameter variation laws.DOI: http://dx.doi.org/10.5755/j01.mech.19.2.4151
Highlights
Piezoelectric pressure transducers must be calibrated in order to determine the linear dependency between applied pressure and the electrical signal yielded at transducer output, measured as the shift of the spot of an oscilloscope
[6, 7], to see if the computed values comply with the adopted mathematical model we drew the same diagram using EES 8.718D software [8]
We clearly distinguish on the diagram the moment when the electric spark is generated by a pressure pin
Summary
One of the methods to analyze the internal combustion processes involves visualizing the pressure evolution inside the cylinder depending on the rotation angle of the crankshaft. If the frequency of the first harmonic was determined to be of 4.583 kHz, than according to Table 1, it can be assessed that the installation characteristic frequency is 45.83 kHz. Piezoelectric pressure transducers must be calibrated in order to determine the linear dependency between applied pressure and the electrical signal yielded at transducer output, measured as the shift of the spot of an oscilloscope. The presence of the transducer connecting channel can represent a source for errors in the recording of cylinder pressures [5]. The gas column under pressure or depression circulates in a dynamic regime from the cylinder towards the transducer membrane This way, a pressure difference appears between the pressure from the measuring point, pi and the one applied to the membrane pm. If the dynamic equilibrium equation is written for the gas column inside the channel, pressure drop due to friction, pf , can be determined: pf l dc dxc 2g dt
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