Volume signal generator for thermodynamic cycle analyzers
AssigneeCaterpillar Tractor Co.
InventorRichard C. Beil
Life of this patent
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Abstract
An improved volume signal generator for use with a thermodynamic cycle analyzer for determining the mean effective pressure of an internal combustion engine, includes an axially rotatable cylindrical cam having a hollow truncated end providing an axially gyrating cam surface about the periphery thereof. A light source located within the hollow truncated end directs a radially disposed beam of light towards a photo diode so as to be cyclically interrupted by the cam surface during operation. The same light source cooperates with openings in the cylindrical wall of the cam and with a second photo diode to produce timing signals representative of the extreme positions of the engine's piston.
Claims1
A volume signal generator for thermodynamic cycle analyzers including a light path and apparatus for mechanically varying the amount of light passing through said path in proportion to the instantaneous volume of the combustion chamber of an engine under analysis, comprising:
- a. uniformly illuminated, elongated slot means positioned in said light path;
- b. axially rotating cam means including a hollow truncated cylinder positioned adjacent to said slot means so as to obscure a portion of said slot means proportional to the axial height of that portion of the cylinder which is closest to said slot means at any given moment at the cylinder's rotation, the truncated surface of said cylinder being so shaped that the axial length of the cylinder wall at any point is proportional to the volume of the combustion chamber of the engine under analysis when that point is nearest said slot means;
- c. light source means for said light path located inside said hollow cylinder, said cylinder wall having at least one opening formed therein;
- and
- d. photoelectric means positioned adjacent said cylinder for receiving light impulses through said opening in said cylinder wall at a predetermined point in the rotation of said cylinder, said light source being a single light source illuminating both said slot means and said opening.
Dependencies are inferred from the claim text.