CONSTANT COMPRESSION

Evening Post, Volume CVI, Issue 132, 15 December 1928, Page 26

CONSTANT COMPRESSION

Inventors have for many years tried to overcome the inefficiency of motor engines due to the variation of compression pressure. A motor engine works at its greatest efficiency when the compression is highest. It stands to reason that with the partly closed throttle insufficient mixture is drawn in, and the compression pressure is therefore less than when the throttle is full open. ■ If, therefore, some means could be devised whereby with a lesser1 mixture drawn in the pressure under com-

pression is Iho sauio as when the combustion chamber had been fully charged by an open throttle, great economy would result. The. latest attempt to meet this situation comes from Prance, whore the iuventor utilises portion of the exhaust gasea to form a strata on the top of the piston, thus filling a portion of the combustion chamber, so ;that when this store of exhaust gas and the lesser quantity of mixture are combined under compression the compression pressure is as high as when the throttle is full open. The functioning of the engine is as fellows': —The piston at its lowest position on- the exhaust stroke uncovers a port which allows some the gases to escape through the port and to remain in the storage chamber, the main body of the exhaust passing out by means of the usual exhaust valve. On the suction stroke, should the throttlo be fully open, the cylinder can receive its full charge of mixture in the usual way, but should the throttle bo partly closed a restriction will be placed to a full charge-entering the cylinder, consequently a partial vacuum will be in the cylinder when the piston nears the bottom of its stroke, which will cause a certain amount of burnt gas to enter the cylinder from the storage chamber to make up a full charge. It is claimed that this amount of burnt gas does not mingle with the mixture drawn in during the previous part of the stroke, but remains as a lower stratum, forming a cushion, which also relieves the force of tho explosion. It is also claimed that the inrushing burnt gas has tho effect of clearing the top of the piston from any carbon deposit. / When starting a cock is closed, •so that conditions are normal. A valve may also be fitted, by means of which the amount of burnt gas which returns to the cylinder can be regulated.

Although many cars are fitted with windscreen wipers, there are still quite a number without this handy device. Those that have ears not so equipped will find this tip useful in securing clear vision during wet weather: —Cut a slice of apple or potato and rub it all over the outside of the windscreen, leaving tho screen wet with juice. The rain will then run down smoothly instead of adhering in drops. After tho rain has worked on the glass for a few • seconds the vision will become almost as clear as through a dry glass. .Some furniture polishes and thin oils are als^ effective.