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Publication numberUS3913545 A
Publication typeGrant
Publication dateOct 21, 1975
Filing dateApr 4, 1973
Priority dateApr 4, 1973
Publication numberUS 3913545 A, US 3913545A, US-A-3913545, US3913545 A, US3913545A
InventorsHaase Lawrence H, Liimatta David R
Original AssigneeFord Motor Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Evaporative emission system
US 3913545 A
Abstract
A fuel vapor recovery system for the adsorption, storage and eventual recycling of vapors to an engine. The system has a vapor-storage canister containing activated carbon for adsorbing fuel vapors from various parts of the engine fuel system. The system selectively purges the fuel vapors for introduction to the engine intake manifold. The purging is controlled in response to engine loading and engine speed for improved engine operation.
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United States Patent 1191 Haase et al.

[451 Oct. 21, 1975 EVAPORATIVE EMISSION SYSTEM [75] Inventors: Lawrence H. Haase, Belleville;

David R. Liimatta, Livonia, both of Mich.

[731 Assignee: Ford Motor Company, Dearborn,

, Mich.

[22] Filed: Apr. 4, 1973 '21 Appl. No.: 347,959

[52] US. Cl 123/136; 123/121 [51] Int. Cl. F02M 25/08 [58] Field of Search 123/136, 121; 60/285, 301

[56] References Cited UNITED STATES PATENTS 3,352,294 11/1967 Biller et al. 123/136 3,674,423 7/1972 Klimisch 60/301 3,680,318 8/1972 Makajima 60/290 Beveridge 123/136 Hollis, Jr 123/136 Primary Examiner-Charles J. Myhre Assistant ExaminerTony Argenbright Attorney, Agent, or Firm.loseph W. Malleck; Keith L. Zerschling [57] ABSTRACT A fuel vapor recovery system for the adsorption, storage and eventual recycling of vapors to an engine. The system has a vapor-storage canister containing activated carbon for adsorbing fuel vapors from various parts of the engine fuel system. The system selectively purges the fuel vapors for introduction to the engine intake manifold. The purging is controlled in response to engine loading and engine speed for improved engine operation.

4 Claims, 1 Drawing Figure US. Patent Oct. 21, 1975 3,913,545

EVAPORATIVE EMISSION SYSTEM BACKGROUND OF THE, INVENTION In an effort to reduce hydrocarbonemissions from the fuel system, various evaporative loss control devices have been proposed, which typically comprise a canister filled with suitable adsorbent material, such as activated charcoal. The carbon adsorbs the hydrocarbon vapors when the engine is not in operation; when the engine is operative, means are provided to effect desorption or purging of the vapors from the adsorbent material so that these vapors can be fed to combustion chambers of the engine for consumption therein. During engine operation, the running vapor losses from both the fuel tank and carburetor bowl are being consumed as they are generated. This approach has worked successfully to reduce hydrocarbon emissions to the atmosphere, but under certain engine operating conditions, the introduction of both the stored and currently generated hydrocarbon vapors for consumption in the engine affects engine operation or causes an increase in the exhaust emission of unburned hydrocarbons. On other occasions, only the stored vapors may cause an over rich air/fuel mixture during the initial portion of the purged cycle. The latter can result in such a rich mixture that engine performance becomes irregular and poor (i.e., hesitation and stumble affecting drivability) and most importantly thecarbon monoxide content of the exhaust is increased.

Although the prior vapor emission systems have been concerned with the need for a controlled purge of hydrocarbon vapors to avoid some of the above problems, the attempts have not been entirely successful. For example, there has been proposed a system which would have two adsorption beds connected in series to each other. Upon purging, the series connected adsorbent beds are unloaded sequentially thereby resulting in some degree of modulated release.

Another approach is the use of a canister bypass for providing a variable purge rate. The canister bypass attempts to smooth out the air/fuel ratio since the amount of air going ultimately through the throat of the carburetor will be'constant, while the amount of air going through the adsorbent material increases or de- 'creasesin the response to the amount of air bypassing the adsorbent. In this manner, a controlled amount of purged fuel vapors may be obtained to some degree.

SUMMARY OF THE INVENTION It is a primary object of this invention to provide an improved apparatus and method for a fuel vapor recovery system; purging of the system is controlled so that overrichness is avoided in the mixturereceiving the recovered vapors and thereby avoid momentary sag or poor engine performance.

Still another object of this invention is to provide a means of controlling the return of excess fuel vapors to the combustion cycle of the engine in such a manner that the carburetor air-fuel ratio is maintained at least above 14/1, thus avoiding a significant change in the combustion products of the engine, such as carbon monoxide. This becomes significant particularly with respect to total auto emission controls which may employ a catalytic converter to reduce unwanted gaseous constituents of the exhaust; in many cases the catalytic converter requires a controlled feed (within a limited range) of carbon monoxide as part of the exhaust being introduced to the catalytic converter.

SUMMARY OF THE DRAWING The FIGURE is a schematicillustration of various components comprising an evaporative emission control systemQThere is shown in cross-section a storage canister for fuel vapors as well as firstand second purge control means and a typical carburetor usedwith a conventional internal combustion engine.

DETAILED DESCRIPTION Referring now to the drawing, there is illustrated a fuel vapor recovery system adapted for recovering fuel vapors which may collect in the carburetor fuel bowl or the vehicle fuel tank. In generahthe recovery system comprises a canister A containing a bed of adsorption material in the form of activated carbon, a passage B communicating the interior of said canister with the intake manifold C of an internal combustion engine D at a location downstream of throttle 11. The recovery system further comprises a first control means E employed to completely shut off or completely open the passage B in response to a vacuum signal received from a location 9 upstream from the throttle 11 of carburetor 12, but downstream from the venturi restriction 13 of the carburetor; this location is commonly referred to as the spark port. A second control means F is employed to operate in series with said first control means and is effective to modulate the flow of fuel vapors through said passage in response to the magnitude of the vacuum received from location 10, thereby controlling the aperture through a portion of passage B.

The canister may typically comprise a container 14 having the bed of adsorption material 15 substantially filling said container, except for an air space 16 defined by a screen 20 at the bottom thereof; a fresh air intake 17 is arranged to admit air to said space 16 during a purging phase of the system. Fuel vapors are conveyed to the canister at the top thereof by way of a conduit 18 leading from a vehicle fuel storage tank and a conduit 19 leading from the carburetor fuel bowl. Thus, during inoperative conditions of the engine or hot soak cycles, fuel vapors are released and adsorbed by the adsorption bed 15, the passage B being closed thereby maintaining atmospheric pressure therein suitable to prevent an induced air flow through 17 but receptive to admit vapors from conduits 18 and 19.

To purge the canister of collected vapors, passage B is placed in communication with a vacuum obtained at location 10 in the intake manifold immediately below the throttle of the carburetor (this location is commonly referred to as the PCV port). The passage B is maintained closed when purging is not desired by the first control means E. Means E comprises a valve housing 26 having a boring or channel 22, one end 22a of the channel serving as the inlet for vacuum; a cross bore 21 intersects with boring 22. Passage B is interrupted by means E so that one break in passage B becomes the inlet at 22a and the other break in passage B becomes the outlet for the vacuum through crossbore 21. A valve 24 (urged by spring 29) is adapted to normally close off the connection between bore 21 and boring 22 by seating against surface 27. Valve 24 is attached to a diaphragm 28 residing in chamber 23; the diaphragm is actuated by a vacuum signal in conduit 25. The vacuum signal is taken at location 9 (commonly referred was the spark port) and'the vacuum here is relatively non-existentat idle or wide-'open-.

ing, control means F is employed to vary the aperture of passage B. Means-F comprises a'valve housing 30 defining an interior valve seat 31 which is progressively closed, but never completely, by a spring biased valve element 32 acting in response to intake manifold vacuum in passage B thereby to vary the spacing between element 32 and the seat 31. Means F functions to allow more flow through, the lower the vacuum pressure; the latter vacuum force purges the vapors and acts proportionate to engine loading. There is a slight bleed through means F even in its most restricted position when vacuum pressure is the highest. Thus, theflow is not preprogrammed independent of engine operation.

We claim: i 1. In an internal combustion engine having a fuel system, an intake manifold and a carburetor with a throttle to provide a gaseous mixture engine flow, an apparatus for controlling the recovery of fuel vapors in said system, comprising: i

'a. means for-adsorbing and storing said fuel vapors, b. a passage for purging said stored fuel vapors and for conveying said vapors to said intake manifold, c. a first control means responsive to vacuum upstream from said throttle for maintaining said pas- 4 sage in either a fullyopen'ed or a fully closed condition, said passage having internal walls defining an aperture between said first control means and said means, for absorbing vapors and through which flow must pass in said passage, and d. a second control means responsive to vacuum in l said intake manifold for regulating the aperture of said passage whereby 'said storing-means is desorbed at a rate inversely proportional to engine flow.

2. An apparatus as in claim 1, in which said second 4. The apparatus as in claim 1, which further comprises, in combination with' said apparatus, an engine exhaust system having a catalytic converter and means calibrated to vary in response to predetermined air/fuel mixtures, said second control means being effective to regulate desorption of 'fuel vapors from said storing means in such amounts as to maintainsaid calibrated means in a condition to provide an air/fuel mixture at 'least above 14/1 whereby the amount'of carbon monoxide in said exhaust gas system is maintained in a predetermined range compatible for operation of said catalytic converter 1 i

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3352294 *Jul 28, 1965Nov 14, 1967Exxon Research Engineering CoProcess and device for preventing evaporation loss
US3674423 *Feb 9, 1970Jul 4, 1972Gen Motors CorpCatalyst for nitrogen oxide reduction
US3680318 *Dec 22, 1970Aug 1, 1972Kunihiko SugiharaCentralized air-pollution preventive system
US3683597 *Sep 17, 1970Aug 15, 1972Gen Motors CorpEvaporation loss control
US3752134 *Apr 5, 1972Aug 14, 1973Gen Motors CorpVapor regulating valve
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4059081 *Jan 26, 1976Nov 22, 1977Toyota Jidosha Kogyo Kabushiki KaishaEVAP system-provided throttle valve control unit
US4070828 *Jan 14, 1976Jan 31, 1978Regie Nationale Des Usines RenaultDevice and method for recycling hydrocarbon vapors of I.C.E. vehicles
US4086897 *Apr 7, 1977May 2, 1978Toyota Jidosha Kogyo Kabushiki KaishaEvaporated fuel feed control device for an internal combustion engine
US4090485 *Mar 28, 1977May 23, 1978Antonio LaCretaFuel systems for internal combustion engines
US4112898 *Apr 7, 1977Sep 12, 1978Toyota Jidosha Kogyo Kabushiki KaishaInternal combustion engine with charcoal canister
US4133328 *Jul 5, 1977Jan 9, 1979General Motors CorporationProportional fuel vapor purge flow control apparatus
US4191154 *Feb 3, 1978Mar 4, 1980Toyota Jidosha Kogyo Kabushiki KaishaEvaporated fuel vapor control device for use in an internal combustion engine
US4203401 *Jan 29, 1979May 20, 1980General Motors CorporationEvaporative emissions canister
US4308842 *Sep 28, 1979Jan 5, 1982Honda Giken Kogyo Kabushiki KaishaEvaporative emission control system for an internal combustion engine
US4326489 *Dec 27, 1979Apr 27, 1982Ford Motor CompanyProportional flow fuel vapor purge control device
US4494504 *Jun 9, 1982Jan 22, 1985Honda Giken Kogyo Kabushiki KaishaStratified burn internal combustion engine
US4530210 *Dec 17, 1982Jul 23, 1985Honda Giken Kogyo K.K.Apparatus for controlling evaporated fuel in an internal combustion engine having a supercharger
US4741317 *Jun 12, 1987May 3, 1988General Motors CorporationVapor recovery system with variable delay purge
US4750465 *Jul 31, 1987Jun 14, 1988General Motors CorporationFuel vapor storage canister
US4836172 *Oct 2, 1987Jun 6, 1989Aisan Kogyo Kabushiki KaishaCanister device for use in gasoline tank
US5188141 *Dec 3, 1991Feb 23, 1993Siemens Automotive LimitedVacuum boost valve
US5199404 *Jun 27, 1991Apr 6, 1993Siemens Automotive LimitedRegulated flow canister purge system
US5366151 *Dec 27, 1993Nov 22, 1994Ford Motor CompanyHybrid vehicle fuel vapor management apparatus
US5368002 *Jun 25, 1993Nov 29, 1994Toyota Jidosha Kabushiki KaishaApparatus for controlling a flow of evaporated fuel from a canister to an intake passage of an engine
US5406927 *Jun 22, 1993Apr 18, 1995Toyoda Jidosha Kabushiki KaishaAir-fuel ratio control apparatus for internal combustion engine
US5408977 *Aug 23, 1993Apr 25, 1995Walbro CorporationFuel tank with carbon canister and shut-off valve
US5515834 *Jul 13, 1995May 14, 1996Toyota Jidosha Kabushiki KaishaAir-fuel ratio control system for an internal combustion engine
US6105708 *Aug 6, 1998Aug 22, 2000Suzuki Motor CorporationPiping device in atmospheric side of canister for vehicle
US6959696Apr 10, 2003Nov 1, 2005Briggs & Stratton CorporationInternal combustion engine evaporative emission control system
US7086390Nov 5, 2004Aug 8, 2006Briggs & Stratton CorporationIntegrated fuel tank and vapor containment system
US7159577Oct 27, 2005Jan 9, 2007Briggs And Stratton CorporationStationary evaporative emission control system
US7165536 *Feb 22, 2005Jan 23, 2007Tecumseh Products CompanyEvaporative emissions control system for small internal combustion engines
US7185640Aug 19, 2005Mar 6, 2007Briggs & Stratton CorporationIntegrated fuel tank and vapor containment system
US7210466 *Nov 23, 2004May 1, 2007Walbro Engine Management, L.L.C.Purge valve and vapor control system
US7267112Jan 14, 2005Sep 11, 2007Tecumseh Products CompanyEvaporative emissions control system including a charcoal canister for small internal combustion engines
US7281525Feb 27, 2006Oct 16, 2007Briggs & Stratton CorporationFilter canister family
US7435289Sep 27, 2005Oct 14, 2008Briggs & Stratton CorporationIntegrated air cleaner and vapor containment system
EP0604285A1 *Dec 17, 1993Jun 29, 1994Magneti Marelli FranceElectrically actuated canistercircuit regeneration valve
WO2004075262A2 *Feb 17, 2004Sep 2, 2004Advanced Tech MaterialsLow pressure drop canister for fixed bed scrubber applications and method of using same
Classifications
U.S. Classification123/520
International ClassificationF02M25/08
Cooperative ClassificationF02M25/0836
European ClassificationF02M25/08C