Valves within Valves
Page 37
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N'ELTY in valve mechanism forms the subject of patent No. 892,415, which deals with the scavenging of multicylindered four-stroke engines. (A. Btichi, Hurden, Canton Schwyz, Switzerland.)
Referring to the drawing, the inlet valve (1) is a large-diameter sleeve seating on its exterior lip and forming a seating for the exhaust valve (2), which moves inside it.
The movement of the inlet valve is performed by a forked rocker (3) against a spring. The exhaust valve is worked by another rocker (4) and its springs are of the hairpin type, acting through the bridge-piece (5). The inlet valve is shown in the open position. the exhaust valve being closed inside it. Charging air is entering the cylinder from an annular space (6) encircling the valves, At top dead centre there is an overlap position in which both valves are open. The charging air can then sweep over the outside face of the inlet sleeve. Then the charging air flows upwards through the exhaust passage and eventually leaves via the exhaust outlet (7).
This occurs on every cycle and is stated to provide a thorough cooling action over both of the valve seats and the va tves.