An Oil Engine with a Cuff Valve
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AN interesting type of engine has been designed in Belgium, and although it is not yet on the market, there are many features which will be of interest to those in this country connected with oil-engine progress.
The unit operates on the two-stroke-cycle system and the air-inlet ports are disposed around the cylinder bore at a level which is a little above that of the top of the piston at bottom dead centre. The principal novelty, however, lies in the form of a reciprocating cuff valve in the cylinder head. This controls the outlet ports. It is actuated through the medium of a special form of rocker and short connecting rod from an overhead camshaft. The cuff valve, under the influence of this camshaft, rises and falls so as to uncover or cover respectively the exhaust ports.
E46 This method ensures a straight-through passage for the air and avoids the loss that usually occurs when the incoming air can, in part, escape through the exhaust ports.
This Serste design ensures effective scavenging, so far as the pressure behind the incoming air can effect it. It is claimed that this method of air control will effectively prevent the accidental accumulation of fuel in the combustion chamber or on the piston crown. Obviously, this is a desirable state of affairs, because the presence of, say, two charges of fuel in the cylinder—owing to the failure of previous combustion—has a detrimental effect upon the lubricant and may cause an excessive pressure increase.
This engine has been designed to run at about 1,500 r.p.m., so that it is suitable for vehicle use and, provided the lubrication of the cuff valve is efficiently arranged, it should provide an efficient method of regulating the working of the exhaust ports.