Abstract: The performance of a compression ignition internal combustion engine is improved by optimizing a cylinder pressure-dependent parameter on a full time, full range basis using in-cylinder pressure measurements to determine the actual value of the parameter to be optimized. The basic procedure is to determine the desired or optimum value of the parameter, determine the actual value of the parameter or a related parameter, and then adjusting an engine operating characteristic such as air/fuel ratio to maintain the controlled parameter at its optimum value. The preferred parameter is a cylinder pressure ratio (CPR) obtained by dividing first and second values of cylinder pressure, and sensed at different points in a thermodynamic cycle, by one another. The sensed values are preferably a first value Po, obtained during the compression stroke, and a second value Pa, obtained after combustion is complete.

Abstract: The performance of a compression ignition internal combustion engine is improved by optimizing excess air ratio (lambda) and/or intake air charge temperature (ACT) on a full time, full range basis. The basic procedure is to first determine the desired or optimum lambda and then to control ACT and intake manifold absolute pressure (MAP) to maintain them at the optimum values for the fuel quantity required at a particular operating point. This approach allows control of both temperature and pressure of the air entering the engine. Full range control requires that lambda and ACT be controlled both upward and downward to achieve optimal engine performance. Control of both lambda and ACT is further enhanced through the use of a supercharger with adjustable input power installed in series with a standard turbocharger compressor of the engine.

Abstract: A pintle nozzle, preferably an unthrottled pintle nozzle, is provided in which a negative interference angle is formed between the conical tip of the nozzle needle and the mating conical valve seat so that the needle seat is located at the bottom of the valve seat rather than at the top. The resulting nozzle lacks any velocity drop downstream of the needle seat, even at very low needle lifts, so that virtually all of the energy used to pressurize the fuel is converted to kinetic energy. Spray dispersion and penetration at low needle lifts therefore are significantly enhanced. Fuel flow through the converging-diameter discharge passage located between the conical needle tip and conical needle seat also self-centers the nozzle needle at low lifts, thereby helping to assure a symmetric spray and to further enhance spray characteristics.

Abstract: A hybrid hydraulic electronic unit injector (HEUI) assembly, having some characteristics of an accumulator-type assembly and some characteristics of a non-accumulator type assembly, is produced by designing the volume (V.sub.ACC) of the passageway downstream of an existing blowback prevention check valve of the assembly to be between 1.0 and 10.0 times the maximum quantity Q.sub.MAX of fuel injected during an injection event. The resulting hybrid assembly 1) exhibits a rising injection rate during at least the initial stages of the injection event and therefore exhibits benefits generally associated with non-accumulator type HEUI assemblies, and 2) exhibits a falling rate injection during at least the final stages of the injection event and therefore exhibits benefits generally associated with accumulator-type HEUI assemblies. The percentage of the injection event taking place under a falling rate increases generally proportionally with the ratio V.sub.ACC /Q.sub.MAX.

Abstract: A solenoid valve assembly incorporates a guide which slidably engages and guides the armature of the assembly's solenoid at a location above the pole piece of the assembly. The guide preferably takes the form of a guide bushing that slidably engages a reduced-diameter end section of the armature. The guide bushing is fixedly disposed in the same tube that surrounds the armature of the solenoid and around which is disposed the solenoid's coil. The solenoid valve assembly exhibits dramatically improved durability when compared to prior art valve assemblies in which the armature was supported in the pole piece. Cycle-to-cycle and valve-to-valve injection uniformity also are enhanced. The solenoid valve assembly is particularly well suited for use in a gaseous fuel injection system for an internal combustion engine because the lack of lubricants in the gas causes rapid wear in valve assemblies having armatures guided in the pole piece.

Abstract: According to the present invention, combustion properties of a gaseous fuel such as natural gas, utilized to fuel an internal combustion engine, are determined by measuring the velocity of sound in the gaseous fuel. This sound velocity measurement is utilized to control and adjust engine performance factors such as ignition timing, fuel flow rate, air/fuel ratio, fuel injection timing, and pilot fuel oil quantity and timing in dual fuel systems. The speed of sound in the gaseous fuel is used to define the hydrogen-to-carbon ratio in the fuel, which is employed in the invention to control and adjust various engine performance factors, and a number of display readouts.

Abstract: A gaseous fuel injection system for a cylinder of an internal combustion engine assures uniform mixing of the gaseous fuel with an air stream being inducted into the cylinder by injecting the gaseous fuel into the air stream at a relatively high velocity, preferably of between a Mach number of 0.5 and a Mach number of 1.0. High Mach injection can be achieved in a remarkably simple and effective manner by 1) using a single or at most a few injection conduit(s) and discharge orifice(s) for each intake port as opposed to a configuration having multiple discharge orifices at a single point in the air intake system upstream of the intake manifold, 2) by setting the relative effective flow areas of the injector metering orifice C.sub.d A1 and conduit discharge orifice C.sub.d A2 such that C.sub.d A2 is between 2 and 5 times greater than C.sub.d A1, and by 3) setting the gas supply pressure to be more than four times the air intake manifold absolute pressure.

Abstract: A non-accumulator-type hydraulic electronic unit injector assembly can be converted to an accumulator-type hydraulic electronic unit injector assembly simply by subjecting the nozzle needle of the injector to downwardly closing forces arising from fluid pressure in the high pressure chamber of the intensifier. This modification causes the needle to remain seated upon intensification of fluid pressure in the high pressure chamber and permits fuel injection to commence only upon subsequent pressure decay in the high pressure chamber. An accumulator volume is formed beneath the blowback avoidance check-valve of the converted injector and can, if necessary, be enlarged by adding the spring chamber of the assembly to the accumulator volume. The resulting assembly could conceivably be retrofitted into an existing injection system on site, or could be assembled as new construction using primarily stock non-accumulator-type assembly components.

Abstract: A standard jerk type fuel injector can be converted to an accumulator type fuel injector by modifying internal flow configurations of the injector from ones which lead to injection whenever fluid pressure in a fuel supply passage thereof exceeds a first designated level to ones which present an accumulator and a control cavity and which lead (1) to injector charging when the fluid pressure in the supply passage exceeds a second designated level and (2) to initiation of injection only upon subsequent pressure decay in the supply passage below a third designated level. The conversion can advantageously be performed by replacing a first spacer having a first set of flow configurations with a second spacer having a second set of flow configurations including a non-return element. The resulting injector has (1) an accumulator volume located fluidically downstream of the non-return element and (2) a control cavity above the nozzle needle.

Abstract: The performance of a gas-fueled unthrottled internal combustion engine is improved by optimizing excess air ratio (lambda) in the engine. Lambda is optimized by selecting automatically and continuously the optimum fraction of cylinders firing (OFF) as a function of engine operating parameters, eliminating the fuel charge from one or more cylinders to obtain firing in the OFF, and distributing the unused fuel to the OFF, thereby decreasing lambda in the firing cylinders to an optimum level. OFF may be calculated according to mathematically derived and empirically weighted equations, or obtained with reference to suitable look-up tables. In addition, optimum lambda and OFF may be adjusted to take into account the effects of exhaust gas recirculation (egr), engine speed, and/or engine timing. Further lambda adjustment can be performed by suitable control of egr, ignition timing, and/or turbo air bypass (TAB).

Abstract: A compression ignition engine can be quickly and easily converted into a dual fuel engine simply by adding a gaseous fuel supply system, by disconnecting the governor actuating lever from the throttle pedal, and by adding an electronic controller which controls the operation of the gaseous fuel supply system and which sets the governor actuating lever at a position which causes the engine to deliver pilot fuel at a desired quantity. Operation is simplified by setting the governor using a droop control technique inherent in governor operation. The system can be automatically calibrated to assure the supply of fuel at a precisely controlled quantity per stroke at all engine speeds. The pilot fuel injection system of the resulting engine is non-invasive and permits inherent safety features of the governor to be retained.

Abstract: An internal combustion engine has a common shared intake port for each pair of cylinders and having a primary fuel injection system capable of controlling very precisely the distribution of fuel into each cylinder by controlling the duration and timing of each injection pulse. A common fuel injector is provided for each shared intake port and is controlled so as to inject fuel into the shared intake port only during the specific intake strokes of individual cylinders. Each injector preferably takes the form of an electronic fuel injector coupled to a controller receiving signals from engine mounted sensors such as a crank angle indicator. Such electronic control permits very precise control of the duration and timing of the fuel injection pulse and also enables other injection strategies such as a skip-fire operation in which fuel injection is withheld during selected intake strokes of selected cylinders, thereby eliminating firing cycles corresponding to the selected intake strokes.

Abstract: An electronic control system controls pilot fuel injection quantity and timing to optimize primary fuel charge ignition. The system includes sensors monitoring engine operating conditions such as engine speed, power demand, intake air temperature, intake manifold pressure, knock, exhaust EGO concentration levels, fuel quality, etc., and a controller which is responsive to these sensors to actuate an electronically controlled pilot fuel injector to adjust pilot fuel injection timing and quantity as required for optimum primary charge ignition. The pilot fuel injector is preferably controlled such that pilot injection quantity is ordinarily increased with increases in air/fuel ratio and charge density and with decreases in engine speed and such that injection timing is ordinarily advanced with increases with engine speed and air/fuel ratio and with decreases in charge density.