Four stroke engine - has auxiliary camshaft to interrupt ignition on alternate strokes for part load operation

摘要

The engine has a normal camshaft (11), on which a lobe (18) works a rocker arm (16) which acts on the stem (20) of the exhaust valve. Another cam works the inlet valve (2). An auxiliary camshaft (5) has lobes (14,6) which operate rocker arms (15,21). One arm (15) acts on a pushrod (19) which depresses the rocker arm (16) of the exhaust valve. The other (21) acts on the stem (4) of an auxiliary inlet valve. For part load operation the auxiliary inlet valve is closed and the exhaust valve held open on every second stroke. For full load operation a control cam (23) moves the shaft (26) on which the auxiliary rocker arms (15,21) pivot.