A Variable-compression Engine
Page 47
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WHEN employing fuels other than petrol, such, for instance, as producer gas, in an engine of normal design, it is usually necessary to alter the compression ratio in order to obtain satisfactory results. The compression may be raised by machining a certain amount of metal off the base of the Cylinder block, or lowered by the introduction of plates.
A. French engineer, M. Daniel Filliol, of Paris, has • hatented a rather ingenious method of raising or lowering the compression of an engine, with the minimum of trouble. By the Filliol system, moreover, it should . be possible, given a sufficiently robust cylinder blocik, pistons, etc., to change a petrol engine into an oil engine emnloying the true Diesel principle. In the Filliol engine the cylinder block slides up and down in the crankcase on guides, the vertical displacement of the block being effected by means of a worm-and-nut arrangement located in the sump and operated by hand from the exterior through gearing.
In the case of a.two-stroke engine, the idea is simplicity. itself, but in a four-stroke the valve mechanism has to be considered. It is obvious that the valve-operating mechanism must move up and down in one with the cylinder block. With valves operated by an overhead camshaft, driven by a vertical shaft, the latter can be made in halves, the upper half being feathered and sliding within the lower one.
With side valves of the normal type, or overhead valves operated by push-rods and rockers, the camshaft can be mounted in the cylinder-block casting instead of in the crankcase, and driven by a vertical shaft which again is in halves. It may be noted that powerful coil springs are introduced between the base of the crank chamber and the under side of the " nut " or plate which raises and lowers the cylinders, to avoid vibration.
With a petrol engine of the Filliol type, the accessories needed, for changing over to the Diesel system are only a fuel pump and a set of injectors mounted in the cylinder heads. When it is desired to change over from petrol to heavy oil, the cylinders are brought down until the required compression ratio is arrived at. The magneto is disconnected and the carburetter throttle fixed wide open for the admission of Pure air, the petrol supply being turned off. The fuel pump is then coupled up and timed.
The Filliol system is open to criticisms, but the idea embodied is interesting and original. It remains to be seen whether the engine will be taken up and developed.
The inventor's address is M. Daniel Filliol, .53, Itue Hoche, Pantin, ( Seine), France.