A Hydrogen Gas Fuel And Management System For An Internal Combustion Engine Utilizing Hydrogen Gas Fuel #5,293,857

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ABSTRACT:

A gas fuel for an internal combustion engine comprising a mixture of gases having a proportion of hydrogen to oxygen of approximately 2:1 and a regulated density of the hydrogen component of the mixture such that the burn rate of the mixture approximates that of a fossil fuel and a system for maintaining the foregoing gas fuel mixture and characteristics in an internal combustion engine.

Hydrogen has long been regarded as an efficient, abundant and potentially non-polluting energy source. Yet despite such desirable attributes, hydrogen has not been widely, or practically, applied in applications where the use of hydrogen as a fuel is self-evidently desirable, such as in motor vehicles powered by internal combustion engines. In part, practical use of hydrogen is inhibited by difficulties in the safe transmission of the gas. Hydrogen has an inherent high volatility and a correspondingly rapid dispersion characteristic in other gas mixtures such as the atmosphere. Further, it is difficult to control the distribution of a hydrogen gas fuel and to maintain consistent combustion characteristics for a hydrogen gas fuel, particularly in a motor vehicle internal combustion engine.

PRIOR ART:

In my present application, I describe an integrated fuel gas management system that enables hydrogen to be efficiently, reliably and safely used as a fuel gas in an internal combustion engine having a configuration de- rived from conventional engines fueled by a fossil fuel, such as gasoline, diesel or other petroleum or hydrocarbon derivative. In the prior art, significant effort directed towards the utilization of hydrogen as a vehicle fuel has attempted to devise a hydrogen powered internal combustion engine that emulates the characteristics of a conventional hydrocarbon fueled (gasoline, diesel, propane, methanol, etc.) engine system. While such an extension of an existing technology to a hydrogen fuel appears logically proper, such prior art techniques have not fully considered: (1) that the volatility, or "burn rate", of hydrogen is many times greater than that of a fossil fuel, and (2) that the combustion "window" for hydro- gen in an oxygen containing atmosphere is exceedingly narrow, and is considerably narrower than that of a fossil fuel.

A fuel such as gasoline or diesel oil will satisfactorily perform and support combustion over a wide range of fuel mixtures having different proportional quantities of oxygen. Hydrocarbon fuels typically support engine speeds over a wide range in an internal combustion engine because of its broad combustion envelope; hydrogen in contrast, will combust satisfactorily only when a hydrogen/oxygen mixture in the ratio of 2:1 is present. This factor makes combustion cycle development for hydrogen fuel a critical art in which the hydrogen burn rate (equated to power output of the engine) and the combustion mixture containing the hydrogen fuel must be carefully regulated over the entire RPM operating range of an engine so that combustion is efficiently supported over the range. The invention herein provides a gas fuel for an internal combustion engine comprising a mixture of gases including hydrogen, oxygen, and other gases that are not combustible with hydrogen in which the mixture includes a proportion of hydrogen to oxygen of approximately 2:1' and a predetermined density of hydrogen within the mixture gases such that the burn rate of the mixture approximates that of a fossil fuel.

There is further management system provided for a fuel gas mixture containing hydrogen that is introduced as a fuel to an internal combustion engine that consists of means and process for monitoring the composition of a fuel gas mixture introduced into the engine such that the proportion of hydrogen to oxygen in the mixture is approximately 2:1; and means and process for modulating the density of the hydrogen component of the introduced fuel gas mixture by the addition of other non- combustible gases to the mixture such that the burn rate of the fuel gas mixture approximates that of a fossil fuel. In the management system, apparatus for the distribution of the fuel gas mixture containing a hydrogen gas component is utilized which is formed from a plurality of conduits having an internal diameter of 0.015 to 0.025 inch intrinsically formed in an otherwise solid member. In addition, the system includes a means and process for the mixing of a proportion of the exhaust gas of the engine into the fuel gas mixture introduced into the engine to provide modulation for the hydrogen in the fuel mixture. Thus, in a further aspect the invention is an improvement to a hydrogen fueled internal combustion engine that includes means and process for modulating the density of the hydrogen component of a fuel gas mixture introduced into the engine such that the burn rate of the fuel gas mixture containing hydrogen is reduced to the approximate burn rate of a fossil fuel. This means and process includes mixing a hydrogen containing fuel gas with at least one of ambient air and exhaust gas from the engine. These features of the invention are explained herein with reference to the figures.

OBJECTS:

It is an object of this invention to overcome such difficulties and to provide a fuel gas management and delivery system for internal combustion engines that utilize hydrogen as a fuel. The system includes a safe and effective distribution means for supplying a hydro- gen fuel to an internal combustion engine, means for fuel injection applications of hydrogen fuel in such an engine, means for controlling the burn rate of hydrogen for the efficient use of a hydrogen fuel gas, and means for overcoming prior art problems of engine shut down caused by an over-enrichment of hydrogen in the fuel supply to the engine.
In particular, when hydrogen gas fuel is used in a motor vehicle internal combustion engine, an over-enrichment of the hydrogen component of the fuel gas injected into the engine frequently occurs and results either in (1) an engine shut down, because of the narrow combustion window (a term defined hereinafter) for hydrogen, or (2) a significant waste of the "over-enriched" portion of the fuel not combusted—the fuel is expelled in the engine exhaust. In prior art attempts, mechanical meters, valves and switches that were conventionally used in engine fuel systems for petroleum based, fossil fuels were too slow to adapt to engine conditions. Similarly, prior art system included processors that were intended to control the engine in view of predetermined operating parameters with little regard for engine effects caused by the injection of a hydrogen fuel. As a result over-enrichment of hydrogen in the fuel/combustion mixture consistently remains a problem in the development of a hydrogen fueled internal combustion engine. Conventional hydrogen fueled engines are prone to shut down and do not smoothly operate over the extended range of engine speeds considered desirable and necessary in a motor vehicle.
It is accordingly an object of this invention to provide a fuel distribution system for a hydrogen fueled internal combustion engine that reduces the problem of fuel over-enrichment and provides a smooth operating characteristic for engine speeds required in conventional use.
It is also an object to provide a "tuned" combustion system, adaptable not only for hydrogen, but also to other fuel stocks by which optimum combustion characteristics are maintained for the fuel over the operating range of the engine.
And it is a further object to provide an integrated operating system including fuel generation and control means for a hydrogen fueled internal combustion engine.
These and other objects of the invention will become evident to those of skill in the art when the following description of the preferred embodiment is considered in conjunction with the drawings in which:

DESCRIPTION OF DRAWINGS:

FIG. 1 shows the combustion envelope of hydrogen compared to the combustion envelope of gasoline and illustrates a goal achieved by the invention in maintaining an optimum and uniform combustion rate for hydrogen throughout the effective range of engine RPM. As used herein, the "combustion envelope" refers to the range within which combustion of a fuel gas is possible, given a predetermined quantity of combustible fuel and its ratio to the combustion media, i.e. oxygen.)

FIG. 2 is a block diagram of a combustion management system for a hydrogen containing fuel gas mixture that is injected into a combustion chamber, showing the interrelationship of system management controls with various engine parameters.

FIG. 3 illustrates the physical arrangement of a hydrogen fuel gas control means and injection system for the regulation of fuel gas transmitted to an engine combustion chamber.

FIG. 4 shows an air gas processor useful in the system of the invention in a cross-sectional side view; FIG. 4A shows a top plan view; and FIG. 4B is a bottom view.

FIG. 5 shows a "quenching conduit" for the safe distribution of a hydrogen fuel in the engine environment, and FIGS. 5A and 5B shows alternative cross section configurations for said conduit.

FIG. 6 figuratively represents the modulating effect upon hydrogen gas characteristics of other non-combustible gases included in a fuel gas mixture containing hydrogen in accord with the invention and its fuel gas management system.

FIG. 7 shows the electron extractor circuit used in the air processor section to ionize and maintain the ionization of introduced air gas.

With reference to FIG. 1, it is an object of the invention to regulate a hydrogen fuel gas mixture that is introduced into the engine combustion chamber such that the burn rate of the hydrogen fuel gas remains constant regardless of engine RPM. As used herein, "burn rate" is an arbitrary measure of the relative volatility of a fuel gas (in contrast with the rate at which a given fuel is consumed, e.a., miles per gallon). Thus, it is an object to regulate the combustion "window" of hydrogen in a gas mixture so that optimum combustion is achieved, regardless of engine speed. With reference to Table I, the extreme volatility of hydrogen in the atmosphere (burn rate: 325-265 cm/sec) is shown in contrast with the relatively equivalent burn rates of several known hydrocarbon and fossil fuels (burn rates: 45-35 cm/sec):

TABLE 1:

The combustion characteristics and high volatility of hydrogen can be charted with reference to an axis correlated to the running speed of an internal combustion engine, as illustrated by the narrow combustion envelope for hydrogen, shown in FIG. 1 at 1 in contrast with the combustion envelope, for example, in gasoline, 2. Typically, in the tuning of an engine for either optimum performance or efficiency, the low volatility and the wide combustion envelope of a fossil fuel permits an engine to be tuned, for example, to an optimum speed corresponding to 60 MPH, without concern for significant adverse effects or need for adjustment over the remaining engine operating range. The narrow combustion envelope of hydrogen, however, prevents such broad tuning and consequently results in fuel over-enrichment and the engine operation difficulties noted above, passim. In the invention, the burn rate of the hydrogen fuel gas is adjusted to be equivalent to that of a fossil fuel by the introduction into the hydrogen fuel of other non- combustible gases that serve as a modulator of the inherent volatility of the hydrogen.

In addition, the hydrogen/oxygen ratio of 2:1 which represents the optimum combustion ratio for a hydrogen fuel is uniformly maintained in the modulated fuel mixture over the engine operating range, e.g. at speeds represented by 3a, 3b, 3c. The combustion window of hydrogen at a modulated given volatility remains in the same 2:1 hydrogen- :oxygen ratio. Thus, the modulated burn rate of the hydrogen fuel gas, adjusted downward to 43-37 cm/sec, is maintained uniformly in the range of speeds from idling to maximum RPM, in contrast with conventional engine design based on typical gasoline burn rate, which is not usually adjusted. Nevertheless, because of the wide combustion window for gasoline, optimum tuning at 60 MPH as shown at 2 in FIG. 1 will allow satisfactory engine operation to other speeds. In the prior art, use of unmodulated hydrogen allowed engine operation only in the narrow envelope figuratively shown in curve 1. In the invention, a processed gas mixture including a hydrogen fuel component-having a uniform, predetermined volatility is generated by the system and introduced into the engine in a proper mixture to insure optimum combustion throughout the range of engine operating speeds.

FIG. 2 shows a block diagram of a complete hydro- gen gas management system. For explanation and illustration purposes, one cylinder of an engine is shown, however, it is appreciated that adaptations of the system to multiple cylinder engines are within the skill of the art. In the system diagram of FIG. 2, there is shown a conventional reciprocating piston internal combustion engine configuration including piston 1 and cylinder 2 connected to a rod and crankshaft mechanism 3, fuel intake valve 4, exhaust valve 5, and spark plug 6. Valves 4 and 5 and spark plug 6 are operatively interconnected to the management system of the invention.

One aspect of an overall system provides a source of fuel gas including hydrogen, such as a water fuel cell, 7, described in my U.S. Pat. No. 4,936,961 including water capacitor 8 immersed in a volume of water 9 which produces a source of a hydrogen/oxygen and non-combustible gas mixture 10 that is operatively interconnected with the gas management system 11 through regulator 13. Preferably the gas management system 11 includes a logic module and central processing unit interconnected to sensors and controllers in the system. The voltage intensifier-circuit 12 regulates voltage amplitude, pulse frequency and gated pulse frequency associated with operation of the fuel cell 7. (See U.S. Pat. No. 4,936,961, FIG. 1, and U.S. Pat. No. 4,798,661.) and is operatively interconnected to the gas management module. The gas pressure regulator 13 is included proximate the exit orifice of the cell to maintain a consistent back pressure (optimally 15 psi in the preferred embodiment) in the fuel delivery system.

The gas management system logic module 11 deter- mines the mixing of the hydrogen fuel gas mixture 10 produced by the cell with other modulating gases such as ambient air, introduced through manifold 14 and/or exhaust gas introduced through gate 15. The management system module includes inputs from sensors relating to air and engine temperature, engine RPM, gas pressure and the vehicle accelerator or engine speed control 40 which determines the speed at which the engine operates. A distributor control 16, as in a conventional internal combustion engine, determines ignition system function 17 and additionally provides an input signal for a tuned gas meter control 18 that is operatively interconnected to the injector port 19 so that a uniform quantity of modulated fuel gas is injected through valve 4 into the cylinder upon each operating cycle of the cylinder. Air gas processor 20 is also included for treatment of gas derived from ambient air introduced in the system through the intake manifold. (See FIGS. 3, 4, 4A, 4B and discussion, infra.) FIG. 3 illustrates an appropriate mechanical configuration adapted to the overall system shown in FIG. 2.

An intake manifold (not shown) directs ambient air 101 to air filter assembly 31 operatively interconnected to an inlet valve 32 which is regulated by the management module and controls the flow of air into air processor 33 which produces a source of ionized non-combustible gases 102, that in turn may be mixed with non-combustible cylinder/engine exhaust gases 103 introduced at exhaust gate 15. These gases are mixed in the intake manifold 35 with gas from the fuel cell 7, introduced at injector port 19 whereupon the modulated combustion mixture having the hydrogen fuel component in the correct proportion with oxygen is delivered to the cylinder at a burn rate equivalent to that of a fossil or hydrocarbon fuel. An oil inlet port 110 for lubrication is optional. Thus, in the air processor ambient air 101 is ionized and the ionized gas 102, and other modulating 65 gas such as the exhaust gas 103 is mixed until the fuel gas 10 for introduction to the cylinder at the modulated burn rate. Lubricating oil mist is shown at 111.