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sleeved camshaft from AE
Page 45
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gives variable valve timing
I/ Improved torque and fuel consumption, ogether with a reduction in oxides of iitrogen and hydrocarbons, are claimed for
twin ohc petrol engine equipped with a am shaft giving variable-valve-timing leveloped in the Turin research department if Associated Engineering Italy SpA. It has teen tested in the Research and )evelopment Centre of Associated 7.,ngineering Developments Ltd, Cawston louse, Rugby.
AED test data reveals that the low speed orque of an engine can be increased by 20 ler cent at 1500 rpm which is reduced to 9 ler cent at 3500 rpm. Specific fuel onsumption is improved by nearly 20 per ent at 1500 rpm and is about the same at .000 rpm. An improvement of pproximately 10 per cent is achieved at 000 rpm and 5 per cent at 4500 rpm.
If the timing is arranged to control the emission of NOX and HC (by increasing valve overlap) reduction of 37,5 per cent and 27.5 per cent respectively are obtainable at a steady speed of 30 mph with a fuel penalty of 3.8 per cent.
Each cam is controlled by a rotatable sleeve mechanism that enables the velocity of the cam to be varied during a revolution and, therefore, the timing of the valve.
A rotating intermediate member is mounted eccentrically to the main shaft and is keyed to a concentrically mounted collar by means of a slider in a radial groove.
A second radial groove in the intermediate member in line with first groove on the opposite side carries a slider which engages a driving pin attached to the cam. The control sleeve is mounted concentric to the intermediate member and its position determines the velocity cycle of the cam.