Patent Issued for Concurrent Injection of Liquid and Gaseous Fuels in an Engine

By a News Reporter-Staff News Editor at Energy Weekly News -- The University of British Columbia (Vancouver, British Columbia, CA) has been issued patent number 8322325, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Rogak, Steven N. (Vancouver, CA); Bushe, William Kendal (Vancouver, CA); McTaggart-Cowan, Gordon (Derby, GB).

This patent was filed on June 29, 2007 and was cleared and issued on December 4, 2012.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates to fuel injection in general and in particular to a method and apparatus for the injection of liquid and gaseous fuels directly into the combustion chamber of an engine.

"The book, The Modern Diesel Engine, (Geoffrey Smith, Ed., Ilife and Sons Ltd, London, 1942) describes the most advanced practical and experimental diesel engine technology up to about 1942. The Ricardo Comet, Lanova air-cell and Acro air-cell systems use a small side chamber connected to the main combustion chamber by a small passage. When the piston moves down, the high pressure gases stored in the side chamber rush through the passage to the main chamber, creating a high-velocity jet that may be used for atomization and mixing of the jet. Cummins Engine Co. produced engines in the 1930's with an air-cell in the piston, which produced an air jet aimed directly at the fuel injector, supposedly improving the air supply to the burning fuel.

"U.S. Pat. No. 6,564,770 B1, May 2003 (Geoffrey Cathcart, assigned to Orbital Engine Company) discloses a 'Method of Injection of a Fuel-Gas Mixture to an Engine'. This patent is directed to co-injection of air and liquid fuel (typically gasoline) into a direct-injection spark ignition engine. By injecting air with the fuel, it is possible to prevent the over-rich regions that would lead to high emissions. The core of the invention seems to be the use of multiple injection events, combined with the air injection, to achieve a desirable fuel-air mixture prior to ignition. The embodiments discussed refer to a spark ignition engine. This patent teaches the trapping of cylinder gases (as opposed to using a compressed air source) for later use in atomizing the fuel.

"U.S. Pat. No. 6,427,660 B1 Aug. 6, 2002 to Yang (assigned to Ford Global Technologies) titled 'Dual Fuel Compression Ignition Engine' disclosed the use of low-pressure (15-45 bar) natural gas and diesel co-injection, typically injected prior to top-dead center to operate in a stratified, mostly premixed combustion mode. Split injections are possible depending on the load. The injector incorporates a mixing-chamber into which diesel is injected through a first valve and sits in the chamber until the gaseous fuel valve opens and the gaseous fuel atomizes the diesel and the whole mixture is injected into the combustion chamber. The fact that the gaseous fuel is at moderately low pressure precludes the possibility of late-cycle gaseous fuel injection (peak cylinder pressures in some engines can approach 100 bar). High gaseous fuel pressure (>250 bar) can be a critical part of maintaining high-efficiency and low emissions with exhaust gas recirculation (EGR).

"U.S. Pat. No. 5,067,467 November 1991 to Hill et al. (originally assigned to the University of British Columbia) titled 'Intensifier-Injector for Gaseous Fuel for Positive Displacement Engines' discloses the idea of using natural gas to continuously atomize diesel in a prechamber without control of the relative timing for liquid pilot and gaseous fuels (i.e., there is no means taught for controlling the liquid/gaseous fuel mass ratio and there is no teaching of anything about metering the liquid fuel or anything about injection phasing). The apparatus described uses a poppet valve injector and the method is described as 'gas blast' atomization.

"U.S. Pat. No. 6,598,584 B2 Jul. 29, 2003 to Beck et al. (Clean Air Partners Inc.) titled 'Gas-Fueled, Compression Ignition Engine with Maximized Pilot Ignition Intensity' relates to pilot-ignition of a premixed natural gas/air charge (commonly referred to as fumigation), the basic concept of which is very old--all the major engine companies have tried variations of this sort. The key novelty disclosed in this patent appears to be the concept of injecting the pilot for a period shorter than the ignition delay or the 'mixing time'. Presumably this results in more widespread ignition of the premixed charge and lower emissions. The patent describes in detail the importance of a particular injector geometry (interference angles for the needle-seat seal).

"U.S. Pat. No. 6,073,862 Jun. 13, 2000 to Touchette et al., (Westport Research) 'Gaseous and Liquid Fuel Injector' includes a detailed review of prior art, including the work of Miyake et al. 1987, who describe a single injector with two concentric needles injecting pilot and high-pressure gaseous fuel through separate holes.

"U.S. Pat. No. 4,414,229 Nov. 22, 1983 to Wood (assigned to Southwest Research) 'Fuel Injection System for Diesel Engines' describes a dual-fuel injector for liquid fuels. As in the other co-injectors reviewed here, the diesel fuel (pilot) is introduced into a chamber in the injector prior to lifting the needle with the pressure of the second fuel. The concept of injecting the pilot first is discussed with respect to efficient ignition. This invention cannot work for a main injection of gaseous fuel because the needle is actuated by an increase in pressure of the alternative fuel. Fuel injectors cannot be actuated rapidly enough by changes in gaseous fuel pressure because gaseous fuel is so compressible. Also, it appears that the intention is to create a 'charge' of diesel fuel (DF) below the alternative fuel (AF) which is all injected essentially sequentially (DF first) when the needle is lifted. There seems to be no way of limiting the DF/AF mass ratio during the early part of the injection.

"U.S. Pat. No. 4,742,801 May 10, 1988, to Kelgard 'Dual Fuel Mobil Engine System' discloses a system for burning gaseous fuels or liquefied petroleum gas (e.g. propane, LPG) in a diesel engine with a pilot diesel engine using separate injectors for the diesel and gaseous fuel.

"U.S. Pat. No. 6,484,699 to Paul et al. teaches a 'universal fuel injector' for automatically switching from injecting a combination of two fuels or one fuel when the second fuel is not available. For example, if the second fuel is a gaseous fuel, liquid fuel is introduced through one connection and gaseous fuel is introduced through a different connector. While the '699 patent discloses a liquid fuel distributor, it does not teach anything about metering the liquid fuel or anything about injection phasing.

"US 2006/0086825 Application to Date et al. filed 24 Oct. 2005 discloses a fuel injector that co-injects gaseous and liquid fuels. The liquid fuel assists with combustion and lubricates the needle at sliding interfaces and where the needle tip impacts against the seat. The application provides no guidance on how to achieve desirable (or even operable) mass ratios of liquid fuel to gaseous fuel during injections."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "The present invention relates to a fuel injector capable of injecting an ignition-promoting liquid fuel (henceforth, simply 'liquid') and a high-pressure gaseous fuel (henceforth, simply 'gas') in an internal combustion engine. The invention pertains specifically to an injector in which both liquid and gas are injected into the combustion chamber through the same injection hole(s).

"The present invention also relates to a method and apparatus for operating an internal combustion engine using a combustible gas under pressure in combination with a controlled quantity of a liquid igniter fuel wherein the controlled quantity of liquid is carried into a combustion chamber and atomized by the flow of gas to the combustion chamber. The liquid can contain additives to reduce exhaust emissions (such as water, alcohols and biodiesel), while the gas can be any blend of hydrocarbons and hydrogen that can be combusted in the combustion chamber, such, as, for example, natural gas, syngas, biogas and mixtures thereof. As found in the recited examples, the gas can also comprise non-reactive gases.

"The liquid start of injection can be slightly delayed from the gas start of injection, in order to control atomization and emissions. The injector is capable of delivering at least a certain minimum liquid/gas mass ratio during the initial part of the injection. Liquid injected during the middle and end of the injection is undesirable. If the initial liquid/gas mass ratio is too high, then liquid atomization can be poor, leading to excessive exhaust emissions. If multiple injections are used for each combustion cycle, then the first injection should have the highest liquid/gas mass ratio. Controlling the liquid/gas mass ratio in the initial part of the injection is an important objective of the method and apparatus described below, not taught in the prior art.

"The present injector introduces the liquid into an accelerating gas stream within the body of the injector to entrain the liquid within the gas for atomization of the liquid as the mixture is injected into the combustion chamber.

"Single-Actuator Embodiments

"Liquid fuel can be metered into the injector by means of a control orifice and a regulated liquid/gas pressure differential, which can be made a function of engine speed. In some embodiments, the liquid fuel flow is further limited by the movement of the needle, which can open or close liquid flow passages in addition to performing its primary function of controlling fuel injection into the engine combustion chamber.

"Dual-Actuator Embodiments

"Liquid fuel can be metered into the injector at controllable times using a second movable needle inside the main needle, an external control valve (such as solenoid, piezo), or an external distributor pump of the sort found on many diesel engines.

"Accordingly, there is provided a method for concurrently injecting a liquid fuel and a gaseous fuel directly into a combustion chamber of an internal combustion engine, the method comprising: delivering the gaseous fuel to a fuel injector; delivering the liquid fuel to the fuel injector; injecting the gaseous and liquid fuels into the combustion chamber by actuating a valve member, whereupon liquid fuel is entrained into the gaseous fuel within a chamber of the injector, and a mixture of gaseous fuel and liquid is injected into the combustion chamber where the expanding gaseous fuel atomizes the liquid fuel; and controlling the mass ratio of the liquid and gaseous fuels during the injecting step so that a majority of the liquid fuel is injected closer to the start rather than the end of the injecting step.

"In a further aspect, there is provided a fuel injector for concurrently injecting a liquid fuel and a gaseous fuel directly into a combustion chamber of an internal combustion engine, the fuel injector comprising: a fuel injector body; a valve member, disposed in a cavity provided within the fuel injector body, and moveable between a closed position when a sealing surface of the valve member is pressed against a seat, and an open position when the valve member is lifted from the seat; a nozzle chamber defined by an annular space between the valve member and the fuel injector body, and in fluid communication with the combustion chamber when the valve member is in the open position; a gaseous fuel supply line in fluid communication with the nozzle chamber through which gaseous fuel is deliverable into the nozzle chamber; an interior passage disposed within the valve member into which the liquid fuel is deliverable from a liquid fuel supply line; and a metering device operatively associated with the fuel injector for controlling dispensing of the liquid fuel from the interior passage into the nozzle chamber so the liquid fuel is entrained in the gaseous fuel flowing through the nozzle chamber during an injection event and so that the majority of the liquid fuel is injected closer to the start rather than the end of the injection event.

"Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures."

For the URL and additional information on this patent, see: Rogak, Steven N.; Bushe, William Kendal; McTaggart-Cowan, Gordon. Concurrent Injection of Liquid and Gaseous Fuels in an Engine. U.S. Patent Number 8322325, filed June 29, 2007, and issued December 4, 2012. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=111&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=5541&f=G&l=50&co1=AND&d=PTXT&s1=20121204.PD.&OS=ISD/20121204&RS=ISD/20121204

Keywords for this news article include: Energy, Oil & Gas, Diesel Fuel, Liquid Fuel, Natural Gas, The University of British Columbia.

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