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A comprehensive investigation on the impact of piston design on scavenging and combustion in an opposed- piston, opposed-cylinder (OPOC) two-stroke engine is carried out and presented in this paper. Two-stroke engines, in general, have superior power densities and brake thermal efficiencies. Compared with opposed-piston (OP) engines, the OPOC architecture comprises only one crankshaft instead of two, and all the forces generated on the piston go to this one crankshaft via a common bearing, thus making the engine structure inherently simple, lightweight, compact and efficient. Due to the piston motion of the OPOC engine, two opposing injectors were mounted at the center of the cylinder wall for each cylinder. This unique feature posed challenges on air entrainment for air/fuel mixing because of the inherent limited space for injection spreading angle near top-dead-center (TDC).

Trucks parked at idle create excessive fuel consumption and exhaust emissions. One of the solutions to this issue is to institute a separate power system, the APU. It will be in operation when vehicle is parked and engine is off to provide the electricity and support the necessary needs (refrigerator, air conditioning, TV, etc.). This paper offers the insight of development of an Electrical Power Cell (EPC) as the candidate of the APU. The device consists of a unique Opposed Piston and Opposed Cylinder (opoc) engine and a high speed rotary generator. An extensive investigation has been conducted during the engine development program to create a special unniflow scavenging process of this two stroke engine. As the result, it realizes zero fresh charge loss with high scavenging efficiency. This paper provides the technical challenges and solutions in achieving the design targets.

An extremely lightweight opposed piston opposed cylinder (opoc) Diesel engine is under development by FEV Engine Technology under a Defense Advanced Research Projects Agency (DARPA) program. FEV and Advanced Propulsion Technologies (APT) were asked by the U.S. Army Tank Automotive Research Development and Engineering Center (TARDEC) to modify this engine for heavy-truck applications. Analyzing the two stroke scavenging, the side-injection combustion, and the structure of the key components shows the potential of the opoc concept. It is predicted for the 465 kW (650 hp) opoc truck engine: Specific power of the dry engine ∼ 2kW/kg (1.2 hp/lb) Engine Height ∼ 40 cm (16 in) Best Efficiency at two sweetpoints ∼ 206 g/kWh (0.339 lb/hph)

Fuel consumption and emissions are reduced through the use of an engine/transmission management system, which prevents unnecessary engine operation. The system is described on a subcompact car with Diesel engine and economy manual transmission. During vehicle deceleration and idle modes (accelerator pedal not depressed) power transmission from the engine is interrupted and the engine is shut off. The engine is operating and power transmission to the wheels is provided only when driving force is required that means when the transmission is in gear and the accelerator pedal is depressed. The interruption and the engagement of power transmission is accomplished by an automatic clutch actuator. Monitoring and control of all system functions is accomplished by a microprocessor.