Piston-less spiral-shaped pressure driven engine
Emin Gabrielyan
Piston-less spiral-shaped pressure driven engine
In [100512 ii] we presented a draft of a pressure driven gear engine. These gear engines suffer from the low efficiency in the pressure usage. The high pressure gas captured in the pocket (in between teeth and the chamber wall) is released in air without employing the pressure of the gas in the pocket. The pocket size remains constant from the moment of the capture until its release into air. Only the expansion of the chamber is employed. The ratio of the chamber expansion is low. The energy efficiency is therefore very low, especially for combustions offering high pressure gas supply. A simple and cycloid gear shapes were discussed. Though the last shape provided a constant velocity ration, it was not solving the energy efficiency problem. The gear rotors are good for inverse processes, i.e. for counters, blowers, and chargers, but not for engines.
Spiral shaped engine
Below we present a spiral shaped solution. It seems highly efficient, as any expansion ratio can be obtained by the choice of the length of the spiral. The animation shows the rotor from the top view, where the immobile blue and the moving red spirals are Z-axis oriented walls. The combustion pressure is supplied at the center. In one cycle, the gas is captured twice, once in the rotating red spiral’s inner (when it closes on the blue immobile one from the outside at 180 degree) and once in the outer pocket of the red spiral (when it closes on the blue one from inside at 360 degree). Once any of these two pockets is closed and captured at the center, the pocket start traveling along the spiral and, when the trip is complete, is released by the exhaust pipe, at the right or the left side of the blue spiral’s external end.
The key characteristic of this spiral design is that the gas pocket expands during its trip in the spiral. The expansion ratio can be brought to any factor by increasing the number of spiral tours. The expansion of the pocket makes use of the pressure of the captured gas now making the engine pressure energy efficient.
Generation of DXF files
The following command line script generates a DXF file of a spiral:
$ perl -e 'use Math::Trig; $r0=1.5; $dr=3.7; $da=10; $maxa=1440; $w=0.2; print "0\nSECTION\n2\nENTITIES\n"; $k=1; for($a=0;;){$r=$r0+$a/360*$dr+$k*$w; $x=$r*cos($a/180*pi()); $y=$r*sin($a/180*pi()); if(defined($x0)&&defined($y0)){ printf "0\nLINE\n10\n%.6f\n20\n%.6f\n30\n0\n11\n%.6f\n21\n%.6f\n31\n0\n",$x0,$y0,$x,$y} $x0=$x; $y0=$y; if($k==1&&$a>=$maxa){$k=-1}else{last if($k==-1&&$a<=0); $a+=$k*$da}} print "0\nENDSEC\n0\nEOF\n"' > a16.dxf
The second spiral is generated by the following modification in the previous script:
$r0=1.5; $dr=3.7; $r0+=$dr/2;
[dxf]
References:
http://fr.wikipedia.org/wiki/Drawing_eXchange_Format
http://www.autodesk.com/techpubs/autocad/acad2000/dxf/line_dxf_06.htm
The emachineshop.com application can import and create a solid model based on the two DXF files.
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Copyright © 2010 by Emin Gabrielyan