Forced Cooling of Exhaust Valves
Page 78

If you've noticed an error in this article please click here to report it so we can fix it.
WITH the present trend towards VY increasing the power of engines, by supercharging or otherwise, the heating of the exhaust valves is becoming the limiting factor in power output. A scheme for positively air-cooling the valves forms the subject of patent No. 885,985. (Caterpillar Tractor Company, 800 Davis Street, San Leandro, California, U.S.A.)
The drawing shows a cylinder head as would be used on a supercharged engine. In addition to water-cooling passages (1 and 2) the exhaust valve-stem is surrounded by an annular space (3). This is connected to the compressed air in the inlet port (4) by an upward passage (5) and a downward one (6). A continuous current of cold air is thus applied to the valve stem, the air departing through the clearance (7) into the exhaust stream.
A flap-valve (8) is provided at the top of the two passages; the object of this is to prevent back-flow if the inlet pressure should be less than that of the exhaust. A second scheme shows the air-cooling sleeve extending almost to the head of the valve.
a20