New Combustion Principle in U.S. Army Truck Engine
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A NEW U.S. Army truck engine I—% featuring a new combustion principle has been developed by Continental Motors and U.S. Army Ordnance. It uses a variety of fuels and has an interesting fuel injection system, developed and supplied by American Bosch Arma Corporation.
Called the Hypercycle LDS-427-2, the engine is now in production at Continental Motors' Muskegon, Michigan, plant and is the first multi-fuel engine to be delivered to the U.S. Army in production quantities.
The engine has undergone extensive testing in the sub-zero temperatures of the Arctic and has also been subjected to the most difficult operating conditions in the high temperatures of the desert. Under these extremes, it has proved capable of operating on any available military fuels, such as petrol, paraffin. diesel fuel, crude oil and all types of jet fuels.
In the Hypercycle combustion system. fuel is sprayed against the wall of a spherically shaped combustion chamber located in the crown of the piston. Through the use of a specially shaped intake port, the induction air is given a swirling motion which persists in the combustion chamber and continues to supply oxygen to the burning fuel. The swirling air provides the correct mixture for burning at the evaporation surface, resulting in an unusually smooth combustion process. The controlled burning of the fuel prevents accumulation of vaporized fuel so that knocking does not occur, even when operating on lowcetane petrol and turbine fuels. This unique combustion development has the
advantage of permitting the use ol standard automotive materials for all other component parts of the engine.
The American Bosch multi-fuel injection system comprises a PSB fuel pump with governor, supply pump, timing unit, spray nozzles and nozzle holders. Its unique design highlights more than 25 years' experience in fuel injection of American Bosch, the U.S.A.'s largest independent manufacturer of injection systems.
To develop an injection system of multi-fuel capability, a major problem was the loss of lubrication within the pumping elements when using low viscosity fuels like petrol and paraffin. Design of a dual-action pumping unit solved this problem. The single camactuated plunger reciprocates for the pumping action and continuously rotates for fuel distribution to the various cylinders. This dual action permits a closer fit within the barrel, or hydraulic head, and prevents plunger seizure with light fuels. Further redesign resulted in the use of engine oil pressure to lubricate the camshaft, camshaft bearings, tappet and lower portion of the plunger. • American Bosch has since incorporated these features in an entire range of fuel injection systems.