Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Reexamination Certificate
1999-04-08
2001-05-29
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
C123S704000, C123S516000
Reexamination Certificate
active
06237575
ABSTRACT:
This invention relates generally to infrared (IR) sensors and more particularly, to automotive pre-vaporized systems utilizing IR sensors for fueling control.
The invention is particularly applicable to and will be described with specific reference to fuel system controls for internal combustion engines using detergent grade gasoline. However, those skilled in the art will readily understand that the invention is applicable to other types of fuel such as diesel fuel and is specifically suited for fueling control of vehicles using multi-fuel systems such as those containing gasoline and alcohol (i.e., ethanol) as well as detergent grade gasolines.
INCORPORATION BY REFERENCE
The following United States patents and articles are incorporated by reference herein and made a part hereof so that details of IR sensors and fueling systems known to those skilled in the art need not be restated herein in detail. None of the patents or articles incorporated herein by reference form any part of the present invention.
U.S. Pat. No. 5,850,821, issued Dec. 22, 1998 to Curtis, entitled “Method and System for Estimating Air/Fuel Ratio of an Engine Having a Non-Heated Fuel Vaporizer”;
U.S. Pat. No. 5,782,275, issued Jul. 21, 1998 to Hartsell, Jr. et al., entitled “Onboard Vapor Recovery Detection”;
U.S. Pat. No. 5,694,906, issued Dec. 9, 1997 to Lange et al., entitled “Fuel Injection System for a Combustion Engine”;
U.S. Pat. No. 5,608,219, issued Mar. 4, 1997 to Aucremanne, entitled “Device for Detecting Gas by Infrared Absorption”;
U.S. Pat. No. 5,529,035, issued Jun. 25, 1996 to Hunt et al., entitled “Cold Start Fuel Injector with Heater”;
U.S. Pat. No. 5,464,983, issued Nov. 7, 1995 to Wang, entitled “Method and Apparatus for determining the concentration of a gas”;
U.S. Pat. No. 5,262,645, issued Nov. 16, 1993 to Lambert et al., entitled “Sensor for Measuring Alcohol Content of Alcohol Gasoline Fuel Mixtures”;
U.S. Pat. No. 5,225,679, issued Jul. 6, 1993 to Clarke et al., entitled “Methods and Apparatus for Determining Hydrocarbon fuel Properties”;
U.S. Pat. No. 4,323,777, issued Apr. 6, 1982 to Baskins et al., entitled “Hydrocarbon Gas Analyzer”;
SAE Paper No. 961957, dated Oct. 14-17, 1996, entitled “Effect of Fuel Preparation on Cold-Start Hydrocarbon Emissions from a Spark-Ignited Engine”;
SAE Paper No. 930710, dated Mar. 1-5, 1993, entitled “Cold Start Performance of an Automotive Engine Using Prevaporized Gasoline”; and
SAE Paper No. 860246, dated Feb. 24-28, 1986, entitled “An Evaluation of Local Heating as a Means of Fuel Evaporation for Gasoline Engines”.
BACKGROUND
A) Evaporative Emission Systems.
Emission regulations prevent release of gasoline vapors to the atmosphere. To meet such regulations, vehicles are equipped with closed evaporative emission control systems which trap vapors that evaporate from the gasoline in the fuel tank in evaporative canisters containing fuel vapor absorbing substances such as charcoal. Emission regulations currently require that the evaporative canisters and the evaporative emission control system pass not only a pressure maintenance test but also a purge flow test which uses engine vacuum to draw fuel vapors from the tank and those stored in the evaporative canister into the engine for combustion.
It has long been known that emitting fuel vapors from the evaporative canisters into the intake manifold adversely affects the air/fuel ratio present in the combustion chambers of the internal combustion engine. The rich mixture produces excessive emissions and adversely affects driveability and/or engine operation. Accordingly, adjustments to the air/fuel mixture, such as disclosed in U.S. Pat. No. 4,003,358 to Tatsutomi et al., issued Jan. 18, 1977, have been made to account for the fuel vapors admitted to the engine from the evaporative canisters. Not surprisingly, as emission regulations have become more stringent, the controls regulating the flow of the fuel vapors to the engine have become more sophisticated. Thus, in U.S. Pat. No. 5,647,332 to Hyodo et al., issued Jul. 15, 1997, the engine control unit judges the operating condition of the vehicle and controls the opening of an atmospheric cannister control valve to control the mass flow of the vapors emitted from the canisters in accordance with the operating condition of the engine. See also U.S. Pat. No. 5,806,500 to Fargo et al., issued Sep. 15, 1998 in which a plurality of canisters connected in series with a by-pass air purge actuated by the engine control module also controls the fuel delivery to the fuel injectors to insure driveability and emission compliance. See also U.S. Pat. No. 5,816,223 to Rummage et al., issued Feb. 16, 1993, which uses pressure transducers and time rate of change to monitor air/vapor flow to the intake manifold vis-a-vis look-up tables and the like to assure combustion stability and prevent engine roughness or stalling.
In general summary, evaporative canister systems use a pressure regulated air purge to control admission of fuel vapors to the engine through any number of control techniques to maintain the air/fuel ratio at or near stoichiometric during normal engine operation. However, the prior art systems cannot account for the change in hydrocarbon concentration of the fuel vapors such as the change in concentration which occurs when and as the fuel vapors are being exhausted from the canisters. While current evaporative control techniques may be acceptable with engines using standard grades of gasoline and current emission standards, conventional systems may not be acceptable under stricter emission regulations which may be proposed in the future and which will require more accurate fueling control. The prior art does recognize that existing evaporative control system techniques are not acceptable when different types of fuel are used in the vehicle. See, for example, evaporative system control changes should the vehicle be subject to fuels containing alcohol as set forth in U.S. Pat. Nos. 4,945,885 to Gonze et al., issued Aug. 7, 1990; 5,111,796 to Ogita, issued May 12, 1992; and, 5,231,969 to Suga, issued Aug. 3, 1993.
B) Cold-Start.
Proposed emission standards require that a regulated drive cycle such as an FTP (Federal Test Procedure) or its European equivalent (an MVG), include a “cold-start” requirement. “Cold-start” conventionally means a condition where the engine and catalytic converter are at temperatures not greater than about 50° C. at the time the engine is started. When the engine is started from a cold condition, the catalytic converter is not catalytically active. In fact, a substantial amount of the emissions produced by the vehicle over a regulated drive cycle are attributed to the emissions produced at cold-start and during engine warm-up following a cold-start. (Warm-up of the engine occurs when the catalytic converter becomes substantially catalytically active, i.e., a condition conventionally defined to mean that 50% of the combustible emissions (CO, HC, H
2
, NO
x
) are converted by the catalytic converter to N
2
, CO
2
and H
2
and often times is referred to as “light-off” of the catalytic converter.) Further, emission sensors, typically EGO (exhaust gas oxygen) sensors, cannot provide a feedback signal at cold-start so the fueling control is open loop and not closed loop.
Emission control at cold-start and during warm-up has generated a separate body of prior art directed to resolving this problem such as the development of light-off catalysts, NO
x
traps, etc.
Most significant, however, is the fact that it is well understood in the prior art that pre-vaporization of the fuel materially reduces the presence of regulated emissions emitted by the engine during cold-start and warm-up. This can be documented from any number of sources such as SAE papers No. 860246, dated Feb. 24-28, 1986, entitled “
An Evaluation of Local Heating as a Means of Fuel Evaporation For Gasoline Engines
”; 930710, dated Mar. 1-5, 1993, entitled “
Cold Start Performance of an Automotive Engine Using Prevaporized Gasoline
”; and 961957, dated Oct. 14-17, 1996,
Heck Ronald M.
Kouznetsov Andrian I.
Lampert Jordan K.
Moser Jeff H.
Robertson Arthur Bruce
Engelhard Corporation
Negin Richard A.
Vo Hieu T.
Yuen Henry C.
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