Navistar International Transportation Corporation

James C McCandless

Terry G Wood

Titus J Iwaszkiewicz

Milan E Zlock

Dale A Oehlerking

An internal combustion engine that is driven by dimethyl ether (DME) and a storage and delivery system for the DME that will reduce considerably the emissions of NO.sub.x and particulate. Existing internal combustion engines, fueled by conventional fuels can be economically converted to the use of DME as a fuel.

Dimethyl ether powered engine

A diesel engine hydraulically-actuated, electronically-controlled unit injector fuel injection system is provided with a two-stage pump system including two parallel pumps for supplying actuating fluid to the injectors. The first stage pump of this two-stage pump has a capacity which is adequate for most operating modes. The second stage pump is used for starting and for high engine load situations. The second stage pump is controlled by a solenoid bypass valve that switches in the second stage pump when the pressure in the high pressure rails fall below a desired or programmed level. An embodiment of this invention includes a second bypass circuit having a fast-response, solenoid-actuated bypass valve that bypasses all of the flow from both stages between injections and thereby produces a pulsed flow of actuation fluid to produce the required pressure for each engine fuel injection while unloading the pumping system between injections.

Actuation fluid pump for a unit injector system

An exhaust back pressure control system includes a valve in the exhaust outlet of a turbocharger of an internal combustion engine which is controlled by an engine control microcomputer. When the valve is moved toward a closed position, it restricts the exhaust flow, thereby increasing back pressure and friction within the engine by producing an artificial load thereon, and thus speeds up the warming process taking place within the engine upon starting thereof. The valve is moved by an actuating piston within a hydraulic cylinder using engine oil pressure controlled by an electrically operated valve receiving a pulse width modulated operating signal from the engine microcomputer, the operating signal being generated to provide a desired back pressure as a function of engine coolant temperature, engine speed, engine fuel comsumption, and actual back pressure. Operation of the system is enabled if the ambient air temperature is below 2.degree. C. and also for the period that the elapsed time since start of engine is less than thirty seconds, the latter enablement being provided to exercise the system during extended periods of warm weather operation when the system would otherwise be inactive.

Exhaust back pressure control system

In combination with a diesel engine, an engine air intake conduit leading preferably to a turbocharger, a source of fuel, and a circuitous fuel path supplying fuel to the engine from the source and returning uncombusted fuel from the engine to the source, is a fuel cooler. The fuel cooler is mounted within the engine air intake conduit upstream of the turbocharger, if present, in a manner allowing intake air to flow through a central passageway of the cooler to the turbocharger. The fuel cooler is further engaged within the circuitous fuel path in a manner allowing heated fuel to travel through a peripheral passageway formed in the fuel cooler. The peripheral passageway is contiguous to the central passageway whereby heat from the heated fuel is transferred to the intake air, thus cooling the fuel. The fuel cooler is used preferably in cooling uncombusted diesel fuel being returned toward the storage tanks of a vehicle from the engine. The fuel cooler comprises an elongate cylindrical body including an integrally molded heat exchanger therein. The heat exchanger has a continuous, convoluted inner wall defining a central passageway therewithin which extends longitudinally through the elongate cylindrical body. The elongate cylindrical body also has a tightly spiralled peripheral passageway cored therein, an inner surface of which forms an outer wall of the heat exchanger. The elongate cylindrical body also has two ports therein, each positioned toward an opposite end of the cylindrical body and opening into and communicating with the cored peripheral passageway.

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Rolling Meadows, IL, United States of America

James C McCandless