Patent Grant
8978626
This invention relates generally to a fuel supply system for an internal combustion engine, particularly for use with a volatile fuel source. More particularly, the invention pertains to an on-board vapor recovery system for condensing gasoline vapors to form a volatile starting fuel and for controlling the operation of an internal combustion engine based on the composition of the fuel within the system.
Hydrocarbon (HC) emissions are a well-known and persistent threat to the environment. Commonly emitted HC species include precursors to smog and agents that are acutely toxic to human, animal and plant life. Moreover, the U.S. Environmental Protection Agency (EPA) has reported that automobile sources contributed 44% of the national emissions inventory of volatile organic compounds (VOC) in 2002. U.S. Environmental Protection Agency Clearinghouse for Inventories & Emissions Factors, “Air Pollutant Emission Trends: 1970-2002 Average Annual Emissions, All Criteria Pollutants” (January 2005). As defined by the EPA, a volatile organic compound is “any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions.” 40 C.F.R. §51.100. Included in this definition are many smog-forming hydrocarbon species.
VOC emissions from modern vehicles are primarily the result of the incomplete combustion of fuel (tailpipe emissions) and the evaporation of fuel stored on-board (evaporative emissions). Tailpipe emissions are highest immediately after starting. At moderate temperatures (20-30° C.), only 10-30% of gasoline vaporizes to join the combustible fuel/air mixture. As liquid fuel does not burn, this necessitates generous over-fueling to provide robust starting. Much of the excess fuel escapes complete combustion and encounters the catalytic converter, which is very inefficient at operating temperatures below approximately 300-350° C. The period of highest tailpipe HC emissions coincides with the period of lowest catalyst conversion efficiency. Consequently, a high percentage of HC emissions occur during the starting and warm-up periods. In fact, between 60 and 95% of all tailpipe emissions occur during the cold-start period, which includes the first 60-90 seconds of engine operation after starting the vehicle. Ashford, M. D., and Matthews, R. D. “Further Development of an On-Board Distillation System for Generating a Highly Volatile Cold-Start Fuel,” SI Combustion and Direct Injection SI Engine Technology, SP-1972, pp 161-167, Society of Automotive Engineers, Warrendale, Pa. (2005), the entire contents of which are incorporated herein by reference.
Research has demonstrated that use of a highly volatile fuel for cold-starting significantly reduces tailpipe HC emissions. See Kidokoro, T., Hoshi, K., Hiraku, K., Satoya, K., Watanabe, T., Fujiwara, T., and Suzuki, H., “Development of PZEV Exhaust Emission Control System,” SAE 2003-01-0817, the entire contents of which is incorporated herein by reference. The vapor inside the fuel tank primarily contains the lightest and most volatile species present in gasoline. See Lyons, J., Lee, J., Heirigs, P., McClement, D., and Welstand, S., “Evaporative Emissions from Late-Model In-Use Vehicles,” SAE Paper No. 2000-01-2958, the entire contents of which are incorporated herein by reference. In one study, speciation of vapor above liquid gasoline at 21° C. revealed that the vapor was dominated by three species—2-methylpropane (isobutane), n-butane, and 2-methylbutane (iso-pentane) collectively accounted for 78% of the vapor composition. See Siegl, W., Guenther, M. and Henney, T., “Identifying Sources of Evaporative Emissions—Using Hydrocarbon Profiles to Identify Emission Sources,” SAE Paper No. 2000-01-1139, the entire contents of which are incorporated herein by reference. In one study, an on-board fuel preprocessor that collected highly volatile fractions of gasoline for use as starting fuel was successful at reducing overall tailpipe HC emissions by more than 80%. See Ashford, M. D., and Matthews, R. D. “Further Development of an On-Board Distillation System for Generating a Highly Volatile Cold-Start Fuel,” SI Combustion and Direct Injection SI Engine Technology, SP-1972, pp 161-167, Society of Automotive Engineers, Warrendale, Pa. (2005). Further studies and research have demonstrated that the most desirable starting fuels are rich in HC species no heavier than C6. See Stanglmaier, R., Roberts, C., Ezekoye, O. and Matthews, R., “Condensation of Fuel on Combustion Chamber Surfaces as a Mechanism for Increased HC Emissions During Cold Start,” SAE Paper No. 1997-01-2884, the entire contents of which are incorporated herein by reference. Thus, vapor from a fuel tank is an ideal source for a starting fuel that is rich in light-weight and highly volatile HC species.
Although tailpipe emissions are substantial, evaporative HC emissions can be three to four times greater than tailpipe emissions during routine driving. Lyons, J., Lee, J., Heirigs, P., McClement, D., and Welstand, S., “Evaporative Emissions from Late-Model In-Use Vehicles,” SAE Paper No. 2000-01-2958. Evaporative emissions can be broken down into several classifications, with running losses and refueling losses accounting for the vast majority of total evaporative emissions. Refueling losses occur when vapor is displaced by liquid entering the fuel tank, a common occurrence at service stations. Running losses occur when vapor is generated in response to heat from hot exhaust, hot pavement, a hot engine compartment, or another hot component of a running engine. Most fuel systems are “return” style systems that supply a large amount of fuel to injectors while returning the excess fuel to the fuel tank. This excess fuel helps keep engine-bay fuel temperatures low, reducing vapor generation and the chance of vapor lock. However, the returning fuel is warmed during its trip through the engine-bay. Also, rear mounted fuel tanks are located in close proximity to hot exhaust pipes, which can be a potent heat source, especially in stop and go traffic. Thus, even though modern fuel return systems help to reduce the amount of vapor generation, a substantial amount of vapor continues to be generated due to heat sources surrounding the fuel tank.
Other classifications of evaporative emissions include diurnal emissions and hot soaks. Diurnal emissions occur when vapor is generated in response to daytime increases in ambient temperature. For example, gasoline tanks may receive considerable heat input via radiation from a hot pavement. In addition, hot soaks occur when vapor is generated due to high temperatures that result from a lack of circulating air or engine coolant after shutdown. Following shutdown, vehicles actually tend to warm up somewhat (especially under the hood) because of a loss of the cooling effect of air flow and water circulation. Naturally, the fuel system is warmed, resulting in the hot soak emissions. These hot soak vapors can become trapped in the fuel system and cause fuel system vapor lock during hot restarts.
The industry-standard solution for preventing the atmospheric release of excess fuel vapor is to collect the vapors in a canister filled with an activated charcoal adsorbent before combusting the vapors when engine operating conditions are favorable. This related art system is shown in
All of the aforementioned factors ultimately result in higher HC emissions. However, several approaches to reducing evaporative emissions exist. So called “returnless” fuel systems reduce running losses by eliminating the return of warm fuel from the engine bay. Newer fuel tanks are vented through the filler neck such that fuel vapors can be recovered by specially equipped fuel station pumps, reducing refueling losses. The newest, cleanest cars in the world (California PZEV-level) are certified to generate zero fuel based evaporative emissions. These vehicles combine returnless fuel systems with highly adsorbent carbon canisters.
Nevertheless, evaporative emissions still represent a significant portion of total vehicular VOC emissions. Despite a decrease in allowable tail pipe emissions by three orders of magnitude over the last thirty years, actual HC emissions have decreased by approximately 80% on a car-by-car basis. Factoring in the increase in vehicle miles traveled over the same period, the aggregate mobile-source HC emissions have only decreased by about half. Furthermore, older vehicles that are not subject to regulations issued after the date of their manufacture may have disproportionately higher emissions as compared to newer vehicles.
It is known that passive starting systems can be incorporated into automobiles to induct hydrocarbon vapors from the carbon canister. A major concern with these systems is the limited production of fuel vapor in cold weather conditions. Under conditions where ambient temperatures are low and there is limited thermal driving force for fuel evaporation, such as, for example, during winter months, the production of fuel vapor is diminished. However, volatile species are added to gasoline in cold climates to enhance cold-start performance, and this increased volatility compensates for the decrease in fuel vapor. However, these systems also suffer from fundamental imperfections. First, there is no way to conclusively know the amount of vapor that can be drawn from the canister. Second, the vapors inducted from the carbon canister are mixed with air, creating a mixture of unknown strength. Thus, these systems are unsuitable for cold-starting, when predictable and robust fueling is essential.
Active recovery of fuel vapor is believed to allow for simultaneous reductions in tailpipe and evaporative emissions. As previously discussed, use of the highly volatile components of fuel vapor as a starting fuel can greatly reduce tailpipe emissions. Thus, it is believed that an effective starting fuel for this purpose can be composed of condensed fuel vapor, which can be stored in isolation and include the most volatile HC species. In addition to the condensate formed from fuel vapor, active vapor recovery can also generate air and trace hydrocarbons that can be stored in a typical vapor canister. It is believed that the separation of the vapor from air will greatly reduce the amount of evaporative hydrocarbon emissions when compared to a normal fuel system.
Given the increasing prevalence of alternative fuels, modern fuel systems and internal combustion engines that are capable of operating with multiple starting fuels are believed to be preferable to fuel systems that are designed to operate with only a single starting fuel. Thus, it is believed that a modern fuel system and internal combustion engine should preferably have multiple operating modes that are adjusted in response to the sensed composition of fuel within the fuel supply system. These multiple operating modes are believed to allow for optimized engine performance regardless of the composition of the fuel used to operate the engine.
Accordingly, it is desirable in the pertinent art to provide an on-board vapor recovery system for use with a fuel supply system and an internal combustion engine that addresses the limitations associated with known systems, including but not limited to those limitations discussed above. Specifically, it is desirable in the pertinent art to provide a vapor-recovery system that can capture, store, and use isolated fuel vapors as a highly volatile fuel source. In addition, it is desirable in the pertinent art to provide an engine control unit for use with a fuel supply system and an internal combustion engine that can select the fuel source and desired operating mode of the internal combustion engine based on the composition of fuel and/or vapor at different locations within the fuel supply system.
In one embodiment of the present invention, a method for controlling the operation of an internal combustion engine in fluid communication with a fuel tank comprises sensing the composition of fuel therein the fuel tank and providing an engine control unit operably coupled to the internal combustion engine, where the engine control unit is configured to select a desired operating mode for the internal combustion engine from a plurality of operating modes of the internal combustion engine based at least on the sensed composition of fuel therein the fuel tank.
In another embodiment of the present invention, a vapor recovery system for an internal combustion engine having a fuel tank comprises a compressor, a condensate tank, a condensate composition sensor, and an engine control unit that selects a desired operating mode of the internal combustion engine based on at least a condensate composition signal and controls the supply of condensate to the internal combustion engine.
Related methods of operation are also provided. Other systems, methods, features, and advantages of the vapor recovery system will be or become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the vapor recovery system, and be protected by the accompanying claims.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain aspects of the instant invention and together with the description, serve to explain, without limitation, the principles of the invention.
The present invention can be understood more readily by reference to the following detailed description, examples, and claims, and their previous and following description. Before the present system, devices, and/or methods are disclosed and described, it is to be understood that this invention is not limited to the specific systems, devices, and/or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.
The following description of the invention is provided as an enabling teaching of the invention in its best, currently known embodiment. Those skilled in the relevant art will recognize that many changes can be made to the embodiments described, while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not in limitation thereof.
As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a “bore” includes aspects having two or more bores unless the context clearly indicates otherwise.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.
In one embodiment, the present invention comprises a method for controlling the operation of an internal combustion engine 28 that is in fluid communication with a fuel tank 10. In one aspect, a means for sensing the composition of fuel therein the fuel tank is in communication with an engine control unit 32 that is operably coupled to the internal combustion engine. In one aspect, the fuel tank 10 can contain a volatile fuel 11, such as, for example and without limitation, gasoline. Of course, it is contemplated that the fuel tank can contain any suitable volatile fuel, including alternative fuel sources.
In one aspect, the engine control unit 32 can be implemented in a programmed general purpose computer. However, it is contemplated that the engine control unit 32 can be a special purpose computer, a program microprocessor or microcontroller with peripheral integrated circuit elements, an ASIC or other integrated circuit, a digital signal processor, a hard-wired electronic or logic circuit, such as a discrete element circuit, a programmable logic device, such as a PLD, PLA, FPGA, or PAL, or any other device capable of implementing the described controls. The engine control unit 32 can be included in a new control unit of a vehicle, or a vehicle can be retrofitted with the engine control unit.
In one aspect, the engine control unit 32 can be configured to select a desired operating mode for the internal combustion engine 28 from a plurality of operating modes of the internal combustion engine based at least on the sensed composition of fuel therein the fuel tank. As one having ordinary skill in the pertinent art will appreciate, pressure, temperature, and other characteristics of the fuel therein the fuel tank can also be used to select a desired operating mode for the internal combustion engine 32. As one having ordinary skill in the pertinent art will further appreciate, the plurality of operating modes can allow the internal combustion engine to operate in an efficient manner with multiple fuel types.
In one embodiment of the present invention, and referring to
In another aspect, as shown in
In another embodiment, as shown in
In another aspect, the vapor recovery system can comprise a condensate composition sensor 21 comprising means for sensing the composition of the condensate therein the condensate tank 20. An mentioned above with regard to the fuel composition sensor, it is contemplated, without limitation, that the means for sensing the composition of condensate can use electrochemical, refractive index, infra-red spectroscopy, or other suitable analysis tools to sense the gasoline-ethanol blend compositional data for volatile fuels. An example of a refractive index sensor that could potentially be used for these purposes is the FRI Refractive Index Sensor, manufactured by FISO Technologies, Inc.
In an additional aspect, and referring to
In one aspect, as shown in
In another aspect, and referring to
Optionally, fuel can be directed from both the fuel tank 10 and the condensate tank 20 to the intake of the internal combustion engine 28. It is also contemplated that a vehicle using the vapor recovery system can be wholly started by using condensate as its fuel source so as to significantly reduce cold start emissions. In addition, it is contemplated that the engine control unit 32 can begin to direct fuel 11 from the fuel tank 10 into the intake 26 of the internal combustion engine 28 approximately 30 to 60 seconds following a cold start accomplished solely through the use of condensate. It is further contemplated that fuel 11 from the fuel tank 10 and condensate from the condensate tank 20 can be simultaneously directed into the intake 26 of the internal combustion engine 28 by the engine control unit 32 to produce a desired volatile fuel mixture.
In one exemplary aspect, as depicted in
In a further aspect, as shown in
In another aspect, and referring to
In a further aspect, as shown in
In one aspect, and referring to
In another aspect, as shown in
In one embodiment, as shown in
In another aspect, and as shown in
In a further aspect, a fuel exhaust sensor can comprise means for sensing the completeness of combustion of fuel therein the internal combustion engine 28. In this aspect, the engine control unit 32 can be operably coupled to the internal combustion engine 28 and in communication with the fuel exhaust sensor for receiving a fuel combustion signal therefrom indicative of the completeness of combustion therein the internal combustion engine. In this aspect, the engine control unit 32 can be configured to select a desired operating mode for the internal combustion engine 28 from a plurality of operating modes of the internal combustion engine based at least on the fuel combustion signal. As one having ordinary skill in the pertinent art will appreciate, fuel composition, pressure, temperature and other characteristics of the fuel therein the fuel tank can also be used to select a desired operating mode for the internal combustion engine 28.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/147,945, filed Jan. 28, 2009, which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2010/022317 | 1/28/2010 | WO | 00 | 8/26/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2010/088328 | 8/5/2010 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3794000 | Hodgkinson | Feb 1974 | A |
| 3807377 | Hirschler et al. | Apr 1974 | A |
| 4945885 | Gonze et al. | Aug 1990 | A |
| 6279548 | Reddy | Aug 2001 | B1 |
| 6526950 | Ito et al. | Mar 2003 | B2 |
| 7347191 | Atwood et al. | Mar 2008 | B2 |
| 7370610 | Ashford et al. | May 2008 | B2 |
| 20050187681 | Suzuki et al. | Aug 2005 | A1 |
| 20060174698 | Chung et al. | Aug 2006 | A1 |
| 20070266632 | Tsangaris et al. | Nov 2007 | A1 |
| 20100011746 | Lupescu | Jan 2010 | A1 |
| 20100024396 | Lupescu et al. | Feb 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 2007098104 | Aug 2007 | WO |
| Entry |
|---|
| Alff et al., An Active Vapor Utilization System for Emissions Reductions in Gasoline-Fuelled Vehicles, Proceedings of the 2008 Technical Meeting of the Central Status Section of the Combustion Institution, pp. 1-6 (2008). |
| Ashford et al., Further Development of an On-Board Distillation System for Generating a Highly Volatile Cold-Start Fuel, SI Combustion and Direct Injection SI Engine Technology, SP-1972, pp. 161-167, Society of Automotive Engineers, Warrendale, PA (2005). |
| Balabin et al., Quantitative Measurement of Ethanol Distribution over Fractions of Ethanol-Gasoline Fuel, Energy & Fuels, 21:2460-2465 (2007). |
| Chen et al., Densities, Viscosities, and Refractive Indices for Binary and Ternary Mixtures of Acetone, Ethanol, and 2,2,4-Trimethylpentane, J. Chem. Eng. Data, 50:1262-1269 (2005). |
| IOB et al., Determination of Oxygenates in Gasoline by FTIR, Fuel, 77(15):1861-1864 (1998). |
| International Search Report and Written Opinion for PCT/US2010/22317 dated May 3, 2010. |
| Kidokoro et al., Development of PZEV Exhaust Emission Control System, SAE 2003-01-0817. |
| Lyons et al., Evaporative Emissions from Late-Model In-Use Vehicles, SAE Paper No. 2000-01-2958. |
| Siegl et al., Identifying Sources of Evaporative Emissions—Using Hydrocarbon Profiles to Identify Emission Sources, SAE Paper No. 2000-01-1139. |
| Stanglmaier et al., Condensation of Fuel on Combustion Chamber Surfaces as a Mechanism for Increased HC Emissions During Cold Start, SAE Paper No. 1997-01-2884. |
| Number | Date | Country | |
|---|---|---|---|
| 20110301823 A1 | Dec 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61147945 | Jan 2009 | US |
