This class contains inventions relating to prime movers orengines in which a combustible material is burned within an inclosed space or chamber and the heat energy thus developed convertedinto work by permitting the resulting products of combustion toact upon and through mechanical powers, the engine in question includingsuitable mechanism whereby the functions above enumerated are continuallyand automatically carried out, and such engine being designed tocommunicate power to some machine or device exterior to itself.
The space or combustion chamber above referred to is ordinarilythe interior of the working cylinder of the engine, the productsof combustion acting immediately upon a reciprocating, rotating,or oscillating piston moving within the same chamber in which combustiontakes place or in an extension thereof. Some types of internal-combustionengines, however, besides fulfilling the conditions above mentioned,have a transfer valve operated by and in unison therewith locatedbetween the combustion chamber and the elements upon and through whichthe products of combustion act to thereby control the flow of saidproducts, in which case the above mentioned transfer valve is operatedto establish communication between the combustion chamber and the workingcylinder at the instant of ignition or prior thereto, so that thepiston is driven by burning products of combustion.
The working fluid is ordinarily such as results from combustionalone; but in some of the engines in this class a small quantityof water is supplied to the engine, generally by injecting it directlyinto the interior of the combustion-chamber during or after thecombustion of the combustible material; but in all engines usingwater the amount used is comparatively small, so that the resultingsteam is necessarily in a superheated condition.
This class also includes separate parts of engines comingwithin the above definition and also subordinate elements designedfor use with such engines, and incapable of use in the manner contemplatedwith other devices or in other relations.
From the above it will be seen that devices go into this classbecause of a function performed by a given element or combinationof elements rather than because of any particular structure of suchelements, and therefore, given structural features forming a machineadapted for use as an internal-combustion engine, may be found in anyother classes having machines of like general structure. Thus probablyany given structure adapted for use as an internal-combustion enginecould generally with slight modification be used as steam or otherheat engine, and often as an air, gas, or water pump, a hydraulicmotor, a meter, etc. This would not ordinarily be the case withthe subordinate or auxiliary devices included in this class, asfrom what appears above such subordinate elements as the class containsare adapted for use in the manner contemplated only with or forminga part of an internal-combustion engine.
It therefore follows that a search for a given general mechanicalstructure adapted for use as an internal-combustion engine willgenerally need to be continued in the classes above indicated.
Further fields of search for the various subordinate elementsdesigned for and adapted to be used only with internal-combustionengines, and therefore included in this class, are indicated inthe definitions hereinafter appearing of those various subclasses.