INGENIOUS VALVE

Hauraki Plains Gazette, Volume 47, Issue 2668, 10 September 1937, Page 6

INGENIOUS VALVE

COPPER AS HEAT CONDUCTOR. r pHE Motor reports on tests recently carried out on an engine fitted with a type of valve recently developed in England in which the high heat conductivity of copper is used to carry away heat from the valve head into the stem. The engine fitted was a six-cylinder one of 21 litres capacity, with the compression ratio raised to 7. 15 to 1, following which the power output was increased by 7 per cent, at 1000 r.p.m. and nearly 10 per cent, at 4000 r.p.m. There was no overheating or preignition, proving that the valves were thoroughly cool.

The construction of the valves, which are used in conjunction with bronze guides, is very interesting. There is, first, an original tulip valve which is drilled up the stem and hollowed out into the head. Into this is forced a copper insert which is shaped to fit into the conical space in the head of the valve, and is also internally drilled and hollowed like the valve itself. The stem- of this piece of copper is slit through so that it can expand in the valve without setting' up bursting strain. To locate the copper insert there is a third member of steel. This is pushed down

the hollow copper portion expanding it so that it makes a firm fit. This third member is also mushroom-head-ed and this head makes a welded steel-to-steel joint with the valve proper.

The three composite sections thus form a rigid composite whole, which is in no danger of disintegration. The valves are not highly expensive to produce' and form a useful contribu-

tion towards high engine efficiency

under heavy load.