If possible, I want to bring experiences of sensor use WPS in the study of the cylinder pressure waveform, The purpose of my test is to verify that the pressure waveform corresponds closely to what is happening in the engine.
I chose a very simple engine and mechanically, which to experiment, it is the Fiat 172B2000, the classic 1108 Fire equipping small cars at Fiat, in this case a 600 of the year 2001.
This engine has a single camshaft, in more possess the values in degrees of the openings - closings of the valves, to be given in the waveform the pressure of the cylinder.
The grades are:
Closed= +7° (367°)
Open= -7° (353°)
closed= +37° (577°)
values are shown in this image:
EXHAUST VALVE OPENING
As can be seen from the first screenshot, the first marker in red indicates the 'opening of the exhaust valve, but the point for translation of opening is moved further forward approximately 10°, I think because the piston is still in the ascending phase and the small opening the valve does not immediately generates a lift of the pressure :
With the valve overlap exhaust / intake, the consideration is more complicated but the intake valve begins to open 7 ° before TDC to 360 ° and the pressure drops immediately, at this point the piston is practically stopped, starts again immediately after its race and we can see a slight curvature of pressure when the exhaust valve closes:
CLOSING INTAKE VALVE
The intake valve closes at + 37 ° (577 °), while the piston is in the ascent phase, in fact the pressure is starting to rise, but we can say that where there 's the slight oscillation of the pressure corresponds to the closing of the valve:
Finally, the response pressure in the opening/closing valve occurs with a slight delay compared to the real point, but we can say that it is a fairly insignificant, for me, depends on what we have to do tests and assessments that are used for diagnosis.
These are considerations of a simple motor, without peculiarities and clearly idling.
If I'm wrong some consideration, correct me and any advice is accepted to grow and learn.
Last edited by tode
on Wed Sep 16, 2015 9:10 pm, edited 1 time in total.