CA1049348A - Combination of a fuel tank venting system and an air-fuel ratio control system of an internal combustion engine - Google Patents
Combination of a fuel tank venting system and an air-fuel ratio control system of an internal combustion engineInfo
- Publication number
- CA1049348A CA1049348A CA248,620A CA248620A CA1049348A CA 1049348 A CA1049348 A CA 1049348A CA 248620 A CA248620 A CA 248620A CA 1049348 A CA1049348 A CA 1049348A
- Authority
- CA
- Canada
- Prior art keywords
- air
- fuel
- fuel ratio
- fed
- engine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 180
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 45
- 239000002828 fuel tank Substances 0.000 title claims abstract description 44
- 238000013022 venting Methods 0.000 title claims description 19
- 239000000203 mixture Substances 0.000 claims description 46
- 239000007789 gas Substances 0.000 claims description 42
- 230000006698 induction Effects 0.000 claims description 27
- 230000003197 catalytic effect Effects 0.000 claims description 9
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 8
- 239000003054 catalyst Substances 0.000 claims description 7
- 229930195733 hydrocarbon Natural products 0.000 claims description 7
- 150000002430 hydrocarbons Chemical class 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 5
- 238000007254 oxidation reaction Methods 0.000 claims description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims 2
- 230000006854 communication Effects 0.000 claims 2
- 239000012530 fluid Substances 0.000 claims 2
- 230000035611 feeding Effects 0.000 claims 1
- 230000002301 combined effect Effects 0.000 abstract 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 239000000306 component Substances 0.000 description 8
- 230000001473 noxious effect Effects 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 239000000809 air pollutant Substances 0.000 description 3
- 231100001243 air pollutant Toxicity 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 235000002020 sage Nutrition 0.000 description 2
- 101100536354 Drosophila melanogaster tant gene Proteins 0.000 description 1
- GENAHGKEFJLNJB-QMTHXVAHSA-N Ergine Natural products C1=CC(C2=C[C@H](CN([C@@H]2C2)C)C(N)=O)=C3C2=CNC3=C1 GENAHGKEFJLNJB-QMTHXVAHSA-N 0.000 description 1
- GENAHGKEFJLNJB-UHFFFAOYSA-N Lysergsaeure-amid Natural products C1=CC(C2=CC(CN(C2C2)C)C(N)=O)=C3C2=CNC3=C1 GENAHGKEFJLNJB-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- YDPHSKXTPWQXBA-QMTHXVAHSA-N ergine Chemical compound C1=CC=C2C3=C[C@@H](C(N)=O)CN(C)[C@@H]3CC3=CN=C1[C]32 YDPHSKXTPWQXBA-QMTHXVAHSA-N 0.000 description 1
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
- F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
- F02M25/089—Layout of the fuel vapour installation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/003—Adding fuel vapours, e.g. drawn from engine fuel reservoir
- F02D41/0042—Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
- F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
- F02M25/0854—Details of the absorption canister
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Supplying Secondary Fuel Or The Like To Fuel, Air Or Fuel-Air Mixtures (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Control Of The Air-Fuel Ratio Of Carburetors (AREA)
Abstract
Abstract of the Disclosure A system for feeding evaporated fuel vapour from a fuel tank into an engine combustion chamber is com-bined with an air-fuel ratio control system to correct the overall air-fuel ratio varied by the evaporated fuel vapour fed into the combustion chamber to a desired air-fuel ratio.
Description
104~348 rhe pre~ent invention relate~ generally to a sy~tem f`or controlling the air-fuel ratio of a-l air-f`uel mixture burned in an internal combustion engine or the overall air-fuel ratio of all air and f`uel fed into the engine to a de~ired value and particularly to a combination of an air-fuel ratio control system and a system for feeding fuel vapour from a fuel tank into a combustion chamber of an internal combustion engine which combination corrects the mixture air-fuel ratio or the overall air-fuel ratio uaried by fuel vapour fed into the combustion chamber to a desired value.
As is well known in the art, it is a basic require- -~
ment for reducing the content.~ of air pollutant~ in exhau~t gases discharged from an engine to accurately 15control the air-fuel ratio of an air-fuel mixture burned ~.
in a combustion chamber of the engine to a desired value.
Particularly, when the engine i8 provided with, for ex-ample, a catalytic converter including a ternal catalyst which concurrently catalytically promotes both oxidation of noxious components such as hydrocarbons(HC) and carbon monoxide(C0) in engine exhau~t gases and reduction of other noxious component such a-~ nitrogen oxide~(N0x) therein to render them harmless, it is necessary to maintain the total or overall air-fuel ratio till before the catalytic converter, that i~, the air-fuel ratio by : 2 ~F
weight of the ~luantities of all air and fue.l fed for formatiol~ of the engine exhaust gaseY fed to the catalytic converter, at a ~toichiometric air-fue.l ratio~
Th.is is because the ternal cataly~t exhibits the above-mentioned function best when the overall air-fuel ratio is maintained at the stoichiometric air-fuel ratio.
Similarly, when the engine is provided with other exhaust gas purifying device such as thermal reactor or a catalytic converter having a reduction or oxidation cataly~t, it is necessary to maintain the overall air-fuel ratio at a specific air-fuel ratio at which the exhaust gas purify-ing device exhibits it~ function best.
As an expedient for controlling the overall air-fuel ratio to a deRired value, there is proposed a system comprising a sensor sensing the concentration of a com-~onent contained in engine exhau~t gases and control means controlling in accordance with the censed concentration of the component valve means of the air-fuel mixture forming device to adjust the amount of fuel fed therefrom for formation of an air-fuel mixture to thereby control.the overall air-fuel ratio to the desired value.
Meantime, an engine is provided with a fuel tank venting system for feeding fuel vapour from the fuel ~torage tank into a combustion chamber of the engine through the induction pas~age to prevent the emissions .. :
of the fuel vapour f`rom the fuel tank into the atmosphere to prevent the contamination of atmo~pheric air. Fuel vapour fed into the combustion chamber cau~es change~ in the mixture air-fuel ratio or the overall air-fuel ratio.
Thi~ results in that the driveability of the engine i~
deteriorated and the exhaust gas treating device cannot di~play its function best to reduce the perf`ormance of purifying air pollutant~ in engine exhaust gases to harmless. Thu~, the fuel tank venting ~y~tem includes a flow control valve which operates in response to suction in the induction passage to control the flow of fuel vapour fed into the combustion chamber to a desired value to prevent variations in the overall air-fuel ratio.
However, it has been in fact impos~ible to accurately con-trol the flow of the fuel YapOUr and accordingly it has been impossible to feed fuel vapour from the fuel tank into the combustion chamber without causing deterioration of the driveability of the engine and a reduction in the performance of purifying the engine exhaust gases.
It is, therefore, an object of the invention to pro-vide a combination of an air-fuel ratio control system and a fuel tank venting system of an internal combustion engine which combination prevents the overall air-fuel ratio from being varied by fuel vapour fed into the com-bustion chamber so that the emissions of fuel vapour from the fuel tank islto the atmosphere is prevented without causing degradation of the operational performance of the engine and a decrease in the performance of purify-ing engine exhaust gases.
5 ` This and other objects and advantages of the invention will become more apparent from the following detailed description taken in connection with the accompanying drawing which is a qchematic view of a preferred embodiment of a combination according to the invention of an air-fuel ratio control syYtem and a fuel tank venting system.
~ Referring to the drawing, there is ~hown an internal combustion engine 10, a fuel tank venting system 12 and an air-fuel ratio control system 14 which are combined with each other. The engine 10 includes an induction passageway 16 communicating with the ambient atmosphere through an air cleaner 18 and opening into a combustion chamber (not shown) of the engine 10 to feed air or an air-fuel mixture into the combustion chamber, and an exhaust gas passageway 20 extending from an exhaust port (not shown) of the combustion chamber and vented to the ambient atmosphere.
An air-fuel mixture forming device 22 is provided to feed fuel or a mixture of fuel and air into air fed z5 by the induction passageway 16 to provide an air-fuel nlixt~lre filling nnd burrled in the combu~tion chamber.
1~ C/lrbllretOr iY em~loyed a~ the mixture formin~y device ~2 in the embodiment and include~ a throttle valve 24 rotatably mounted in the induction paYsageway 16. A
l`uel injection device or injector may be employed as the mixture forming device 22 in place of the carburetor.
The mixture forming device 22 includes valve means(not shown) which, for example, is a valve di~po~ed in a fuel or air bleed pas~age in the caqe of a con~tant choke carburetor or in a fuel or air bypa~ paqsage formed around a throttle valve in the ca~e of a variable choke carburetor or which is a fuel injection valve in the case of a fuel injector. The valve means adjustq the amount of fuel fed from or air fed into the mixture forming device for formation of the engine air-fuel mixtureO An actuator 26 is provided to operate the valve means and may be a solenoid, a servo motor or a diaphragm device.
An exhaust gas purifying or treating device 28 iq located in the exhau~t gas pa~ageway 20 and i~ an exhaust gas catalytic converter which contains therein a ternary or three-way cataly~t(not shown) in the embodiment. The ternary catalyst serves to concurrently catalytically promote both oxidation of noxious com-ponents ~uch as hydrocarbonY(HC) and carbon monoxide(C0) _ 6 --~049348 ~)reAent in exhaust gase~ discharged from the ergine 10al~d reduction o~ other noxious component such as tli trogell oxides(N0 ) to render these noxious components harmless. The ternary catalyst displays the above-mentioned function best when the overall air-fuel ratio is at a stoichiometric air-fuel ratio. The exhaust gas purifying device 28 may includes a secondary air supply device(not shown) for feeding secondary air into the exhaust gas passageway 20 at a position upstream of the exhaust gas purifying device 28 to assist and promote reaction or combustion of noxious components in the engine exhaust gases therein. In this instance, the overall air-fuel ratio is the ratio of air in an engine air-fuel mixture plus secondary air to fuel in the mixture.
The fuel tank venting system 12 serves to conduct evaporated fuel vapour in a fuel tank into the combustion chamber for combustion therein to prevent or reduce the amount of fuel vapour escaping from the fuel tank to the atmosphereO The fuel tank venting system 12 comprises a fuel storage tank 30 for storing liquid fuel to be fed to the engine 10, and a fuel vapour passage 32 extending from the upper portion of the fuel tank 30 and opening into the induction paqsageway 16 at a position downstream of the throttle valve 24 or into an 104934~
engille intake manifold 34 forming part of the induction passageway 16 to conduct evaporated fuel vapour from the luel tank 30 thereinto. A condense tank or vapour-li(luid separ~tor 36 is disposed in the fuel vapour passage 32 and communicates at its lower portion with the upper portion of the fuel tank 30 through a passage 38. The separator 36 serves to separate and collect liquid contained in the evaporated fuel vapour from the fuel tank 30 and return the liquid thereinto through the passage 38.
A canister 40 is disposed in the fuel vapour passage 32 at a location downstream of the separator 36 and includes a housing 42 containing therein two oppo~ite filters 44 and 46 which are spaced apart from each other and defines a chamber 48 therebetween. The housing 42 is provided with an air inlet port 50 vented to the outside atmosphere and communicating with the chamber 48 through the filter 44 and further has an inlet chamber 52 communicating with the separator 36 through the passage 32a and with the chamber 48 through a filter 54,and an outlet chamber 56 communicating with the chamber 48 through the filter 46. The chamber 48 contains therein vapour absorption means such as activated carbon or charcoal 58 which functions in known manner to absorb the evaporative emi~sions from the fuel tank 30 and preclllde their discharge into the atmo~lhere thlough the air inlet port 50.
A flow control valve 60 i9 dispo~ed in the fuel vapour passage 3Z at a position downstream of the canister 40 to control or meter the flow of fuel vapour fed into the induction passageway 16 to a de~ired or predetermined ratio to the flow of air drawn into the combustion chamber through the induction pas~ageway 16.
The flow control valve 60 compri~es a hou~ing 62, and a pressure respon4ive deformable partition member such as a flexible diaphragm 64 dividing the interior of the housing 62 into a vacuum chamber 66 and a fuel vapour chamber 680 The vacuum chamber 66 communicates through a passage 70 with the induction passageway 16 at a po-sition immediately upstrea~ of the throttle valve 24 inits fully closed po4ition. The fuel vapour chamber 68 communicates through the pa~sage 32b with the induction passageway 16 downstream of the throttle valve 24. An outlet passage 72 projects from the outlet chamber 56 into the fuel vapour chamber 68 and is formed therein with an orifice 74. The diaphragm 64 serve~ as valve means or includes valve means(not shown) fixedly secured thereto which is engageable with the free end of the outlet pa~sage 72 to clo~e the fuel vapour passage 32. The valve means operates to increa~e and ~049348 reduce the degree of opening of the flow control valve 60 to the ~as~age 32 in response to an increase and a decrease in the vacuum in the induction passageway 16 at a position downstream of the throttle valve 2l~ in its open poYitions. A spring 76 iA provided to urge the diaphragm 64 into a position in which the valve means closes the fuel vapour passage 32.
The air-fuel ratio control system 14 serves to control or correct to a desired or predetermined air-fuel ratio the air-fuel ratio of an air-fuel mixture burned in the combustion chamber or the overall or total air-fuel ratio of all air and fuel fed into the combustion chamber and engine exhaust gases till reach-ing the exhaust gas purifying device 28 which ratio is varied by evaporated fuel vapour fed from the fuel tank 30 into the combustion chamber. The air-fuel ratio control ~ystem 14 comprises sensing means 78 located in the exhaust gaY passageway 20 at a location upstream of the exhaust gas treating device 28 and sensing the concentration of a component s~uch as oxygen (2)~
carbon monoxide(C0), carbon dioxides(C02), hydrocarbons (HC), or nitrogen oxides(N0 ) contained in engine exhaust gases which concentration is cloYely related to or represents the mixture air-fuel ratio or the overall air-fuel ratioO An oxygen sens~r is employed as the sen~ing mean~ 78 in this embodiment and generates an electric output signal having a value or magnitude representing the sensed concentration of oxygen. The oxygen sen~or 78 is electrically connected to a control or comparator circuit 80 to apply the output ~igna]
thereto. The comparator circuit 80 compares the value of the output signal from the oxygen sensor 78 with a desired reference value which represents the desired air-fuel ratio which i9 a stoichiometric air-fuel ratio when the exhaust gas treating device 28 is a catalytic reactor including a ternary catalyst as in this embodiment.
The comparator circuit 80 generates an electric output or error signal having a value or width repre~enting a difference between the value of the output signal of the oxygen sensor 78 and the reference value, or the largeness or smallness of the value of the output ~ignal to the reference value. Thè comparator circuit 80 is electrically connected to the actuator 26 of the mixture forming device 22 to apply the output signal thereto.
The actuator 26 is actuated in accordance with the value of the output signal of the comparator circuit 80, for example, to adjust the ratio of open time and closed time of the valve means of the mixture forming device 22 to adjust the amount of fuel or air fed there- ~' ~5 from or-into for formation of an engine air-fuel mixture to 1049;~48 correct the overnll air-fuel ratio to the de.~ired air-~`uel ratio.
The combir-ation of the fuel tank venting Yystem and the air-fuel ratio control system thu~ far described is operated as follow~:
The evaporated fuel vapour (mainly unburned hydro-carbons) in the fuel tank 30 i9 drawn into the fuel vapour passageway 32 toward the canister 40 by the pressure therein les~ than the pressure in the fuel tank 30. A portion of and/or liquid in the fuel vapour is liquefied and/or separated in the separator 36 and is returned into the fuel tank 30. The remaining fuel vapour is drawn into the chamber 48 of the canister 40 through the passage 32a and the inlet chamber 52 and is absorbed by the absorber 58. Atmospheric air is concurrently drawn into the chamber 48 through the air inlet port 50. Suction from the induction passageway 16 acts on the canister 40 through the pasYage 70 to release the fuel vapour from the absorber 58 and draw a mixture of the fuel vapour and atmospheric air of an amount metered by the flow control valve 60 into the induction passageway 16 through the passage 32bo The mixture of the fuel vapour and air thus drawn is conducted into the combustion chamber through the induction passageway 16 to cause a variation in the nir-fuel ratio of an engine air-fuel mixture and is burned in the combustion chamber together with the en~ine air-fuel mixture to produce engine exhaust gases which is discharged into the exhaust gas passageway 20.
The oxygen sen~or 78 senses the concentration of oxygen present in the engine exhaust gases which con-centration represents the overall air-fuel ratio varied by the fuel vapour and air fed into the combustion chamber. The sensor 78 generates an output signal represents the sensed concentration of oxygen. The comparator circuit 80 compares the value of the output signal of the sensor 78 with the reference ~alue and generates an output signal representing the excess or deficiency of fuel or the deficiency or excess of air when the overall air-fuel ratio is les~ or greater than the desired air-fuel ratio. The actuator 26 is caused by the output signal of the comparator circuit 80 to open the valve means of the mixture forming device 22 to reduce or increase the amount of fuel fed therefrom or to increase or reduce the amount of air fed thereinto to form an engine air-fuel mixture diluted or enriched to the extent that the overall air-fuel ratio is increased or reduced to the desired air-fuel ratio. Thus, the overall air-fuel ratio is maintained at the desired air-fuel ratio irrespective of the amount of the eYaporated fuel VapOUr : ' :' .
- . '~ . . : -fed from the f`uel tank 30 into the combustion chamber.
As a result, the driveability of the engine 10 i~
stabili~.ed and the exhaust gas purifying device 28 exhibits its function best to minimize the contents of air pollutants in engine exhaust gases emitted therefrom.
Although, with a fuel tank venting system which is not combined with an air-fuel ratio control system, it has been necessary to make great efforts in, for example, adjusting a flow control valve to allow the flow of fuel vapour fed into an engine induction pa~sage-way to come as near to a de~ired value as possible, with a fuel tank venting system which is combined with an air-fuel ratio control system as according to the in-vention, it is unnecessary to make ~uch efforts and an advanta$e i9 obtained that means for controlling the flow of fuel vapour can be simplified to, for example, an orifice.
It will be appreciated that the invention provides a combination of a fuel tank venting system and an air-fuel ratio control system which combination controls orcorrects the overall air-fuel ratio varied by evaporated fuel vapour fed from a fuel tank into a combustion chamber of the engine to a desired air-fuel ratio 90 that the evaporated fuel vapour can be fed from the fuel tank into the combustion chamber without causing the _ 14 -deteriotation of the driveability of the engine and reducing the performance, of an exhauYt gas treating device of the engine, of treating engine exhaust gases.
Although the invention has been described as being applied to an engine including a catalytic converter having a ternal catalyst, the invention Carl be applied to an engine including other exhaust gas purifying device such a~ a thermal reactor or a catalytic converter having a reduction or oxidation catalyst. In this in-stance, a desired value of the overall air-fuel ratio is a value at which the exhaust gas treating device exhibits its function or performance best.
:
As is well known in the art, it is a basic require- -~
ment for reducing the content.~ of air pollutant~ in exhau~t gases discharged from an engine to accurately 15control the air-fuel ratio of an air-fuel mixture burned ~.
in a combustion chamber of the engine to a desired value.
Particularly, when the engine i8 provided with, for ex-ample, a catalytic converter including a ternal catalyst which concurrently catalytically promotes both oxidation of noxious components such as hydrocarbons(HC) and carbon monoxide(C0) in engine exhau~t gases and reduction of other noxious component such a-~ nitrogen oxide~(N0x) therein to render them harmless, it is necessary to maintain the total or overall air-fuel ratio till before the catalytic converter, that i~, the air-fuel ratio by : 2 ~F
weight of the ~luantities of all air and fue.l fed for formatiol~ of the engine exhaust gaseY fed to the catalytic converter, at a ~toichiometric air-fue.l ratio~
Th.is is because the ternal cataly~t exhibits the above-mentioned function best when the overall air-fuel ratio is maintained at the stoichiometric air-fuel ratio.
Similarly, when the engine is provided with other exhaust gas purifying device such as thermal reactor or a catalytic converter having a reduction or oxidation cataly~t, it is necessary to maintain the overall air-fuel ratio at a specific air-fuel ratio at which the exhaust gas purify-ing device exhibits it~ function best.
As an expedient for controlling the overall air-fuel ratio to a deRired value, there is proposed a system comprising a sensor sensing the concentration of a com-~onent contained in engine exhau~t gases and control means controlling in accordance with the censed concentration of the component valve means of the air-fuel mixture forming device to adjust the amount of fuel fed therefrom for formation of an air-fuel mixture to thereby control.the overall air-fuel ratio to the desired value.
Meantime, an engine is provided with a fuel tank venting system for feeding fuel vapour from the fuel ~torage tank into a combustion chamber of the engine through the induction pas~age to prevent the emissions .. :
of the fuel vapour f`rom the fuel tank into the atmosphere to prevent the contamination of atmo~pheric air. Fuel vapour fed into the combustion chamber cau~es change~ in the mixture air-fuel ratio or the overall air-fuel ratio.
Thi~ results in that the driveability of the engine i~
deteriorated and the exhaust gas treating device cannot di~play its function best to reduce the perf`ormance of purifying air pollutant~ in engine exhaust gases to harmless. Thu~, the fuel tank venting ~y~tem includes a flow control valve which operates in response to suction in the induction passage to control the flow of fuel vapour fed into the combustion chamber to a desired value to prevent variations in the overall air-fuel ratio.
However, it has been in fact impos~ible to accurately con-trol the flow of the fuel YapOUr and accordingly it has been impossible to feed fuel vapour from the fuel tank into the combustion chamber without causing deterioration of the driveability of the engine and a reduction in the performance of purifying the engine exhaust gases.
It is, therefore, an object of the invention to pro-vide a combination of an air-fuel ratio control system and a fuel tank venting system of an internal combustion engine which combination prevents the overall air-fuel ratio from being varied by fuel vapour fed into the com-bustion chamber so that the emissions of fuel vapour from the fuel tank islto the atmosphere is prevented without causing degradation of the operational performance of the engine and a decrease in the performance of purify-ing engine exhaust gases.
5 ` This and other objects and advantages of the invention will become more apparent from the following detailed description taken in connection with the accompanying drawing which is a qchematic view of a preferred embodiment of a combination according to the invention of an air-fuel ratio control syYtem and a fuel tank venting system.
~ Referring to the drawing, there is ~hown an internal combustion engine 10, a fuel tank venting system 12 and an air-fuel ratio control system 14 which are combined with each other. The engine 10 includes an induction passageway 16 communicating with the ambient atmosphere through an air cleaner 18 and opening into a combustion chamber (not shown) of the engine 10 to feed air or an air-fuel mixture into the combustion chamber, and an exhaust gas passageway 20 extending from an exhaust port (not shown) of the combustion chamber and vented to the ambient atmosphere.
An air-fuel mixture forming device 22 is provided to feed fuel or a mixture of fuel and air into air fed z5 by the induction passageway 16 to provide an air-fuel nlixt~lre filling nnd burrled in the combu~tion chamber.
1~ C/lrbllretOr iY em~loyed a~ the mixture formin~y device ~2 in the embodiment and include~ a throttle valve 24 rotatably mounted in the induction paYsageway 16. A
l`uel injection device or injector may be employed as the mixture forming device 22 in place of the carburetor.
The mixture forming device 22 includes valve means(not shown) which, for example, is a valve di~po~ed in a fuel or air bleed pas~age in the caqe of a con~tant choke carburetor or in a fuel or air bypa~ paqsage formed around a throttle valve in the ca~e of a variable choke carburetor or which is a fuel injection valve in the case of a fuel injector. The valve means adjustq the amount of fuel fed from or air fed into the mixture forming device for formation of the engine air-fuel mixtureO An actuator 26 is provided to operate the valve means and may be a solenoid, a servo motor or a diaphragm device.
An exhaust gas purifying or treating device 28 iq located in the exhau~t gas pa~ageway 20 and i~ an exhaust gas catalytic converter which contains therein a ternary or three-way cataly~t(not shown) in the embodiment. The ternary catalyst serves to concurrently catalytically promote both oxidation of noxious com-ponents ~uch as hydrocarbonY(HC) and carbon monoxide(C0) _ 6 --~049348 ~)reAent in exhaust gase~ discharged from the ergine 10al~d reduction o~ other noxious component such as tli trogell oxides(N0 ) to render these noxious components harmless. The ternary catalyst displays the above-mentioned function best when the overall air-fuel ratio is at a stoichiometric air-fuel ratio. The exhaust gas purifying device 28 may includes a secondary air supply device(not shown) for feeding secondary air into the exhaust gas passageway 20 at a position upstream of the exhaust gas purifying device 28 to assist and promote reaction or combustion of noxious components in the engine exhaust gases therein. In this instance, the overall air-fuel ratio is the ratio of air in an engine air-fuel mixture plus secondary air to fuel in the mixture.
The fuel tank venting system 12 serves to conduct evaporated fuel vapour in a fuel tank into the combustion chamber for combustion therein to prevent or reduce the amount of fuel vapour escaping from the fuel tank to the atmosphereO The fuel tank venting system 12 comprises a fuel storage tank 30 for storing liquid fuel to be fed to the engine 10, and a fuel vapour passage 32 extending from the upper portion of the fuel tank 30 and opening into the induction paqsageway 16 at a position downstream of the throttle valve 24 or into an 104934~
engille intake manifold 34 forming part of the induction passageway 16 to conduct evaporated fuel vapour from the luel tank 30 thereinto. A condense tank or vapour-li(luid separ~tor 36 is disposed in the fuel vapour passage 32 and communicates at its lower portion with the upper portion of the fuel tank 30 through a passage 38. The separator 36 serves to separate and collect liquid contained in the evaporated fuel vapour from the fuel tank 30 and return the liquid thereinto through the passage 38.
A canister 40 is disposed in the fuel vapour passage 32 at a location downstream of the separator 36 and includes a housing 42 containing therein two oppo~ite filters 44 and 46 which are spaced apart from each other and defines a chamber 48 therebetween. The housing 42 is provided with an air inlet port 50 vented to the outside atmosphere and communicating with the chamber 48 through the filter 44 and further has an inlet chamber 52 communicating with the separator 36 through the passage 32a and with the chamber 48 through a filter 54,and an outlet chamber 56 communicating with the chamber 48 through the filter 46. The chamber 48 contains therein vapour absorption means such as activated carbon or charcoal 58 which functions in known manner to absorb the evaporative emi~sions from the fuel tank 30 and preclllde their discharge into the atmo~lhere thlough the air inlet port 50.
A flow control valve 60 i9 dispo~ed in the fuel vapour passage 3Z at a position downstream of the canister 40 to control or meter the flow of fuel vapour fed into the induction passageway 16 to a de~ired or predetermined ratio to the flow of air drawn into the combustion chamber through the induction pas~ageway 16.
The flow control valve 60 compri~es a hou~ing 62, and a pressure respon4ive deformable partition member such as a flexible diaphragm 64 dividing the interior of the housing 62 into a vacuum chamber 66 and a fuel vapour chamber 680 The vacuum chamber 66 communicates through a passage 70 with the induction passageway 16 at a po-sition immediately upstrea~ of the throttle valve 24 inits fully closed po4ition. The fuel vapour chamber 68 communicates through the pa~sage 32b with the induction passageway 16 downstream of the throttle valve 24. An outlet passage 72 projects from the outlet chamber 56 into the fuel vapour chamber 68 and is formed therein with an orifice 74. The diaphragm 64 serve~ as valve means or includes valve means(not shown) fixedly secured thereto which is engageable with the free end of the outlet pa~sage 72 to clo~e the fuel vapour passage 32. The valve means operates to increa~e and ~049348 reduce the degree of opening of the flow control valve 60 to the ~as~age 32 in response to an increase and a decrease in the vacuum in the induction passageway 16 at a position downstream of the throttle valve 2l~ in its open poYitions. A spring 76 iA provided to urge the diaphragm 64 into a position in which the valve means closes the fuel vapour passage 32.
The air-fuel ratio control system 14 serves to control or correct to a desired or predetermined air-fuel ratio the air-fuel ratio of an air-fuel mixture burned in the combustion chamber or the overall or total air-fuel ratio of all air and fuel fed into the combustion chamber and engine exhaust gases till reach-ing the exhaust gas purifying device 28 which ratio is varied by evaporated fuel vapour fed from the fuel tank 30 into the combustion chamber. The air-fuel ratio control ~ystem 14 comprises sensing means 78 located in the exhaust gaY passageway 20 at a location upstream of the exhaust gas treating device 28 and sensing the concentration of a component s~uch as oxygen (2)~
carbon monoxide(C0), carbon dioxides(C02), hydrocarbons (HC), or nitrogen oxides(N0 ) contained in engine exhaust gases which concentration is cloYely related to or represents the mixture air-fuel ratio or the overall air-fuel ratioO An oxygen sens~r is employed as the sen~ing mean~ 78 in this embodiment and generates an electric output signal having a value or magnitude representing the sensed concentration of oxygen. The oxygen sen~or 78 is electrically connected to a control or comparator circuit 80 to apply the output ~igna]
thereto. The comparator circuit 80 compares the value of the output signal from the oxygen sensor 78 with a desired reference value which represents the desired air-fuel ratio which i9 a stoichiometric air-fuel ratio when the exhaust gas treating device 28 is a catalytic reactor including a ternary catalyst as in this embodiment.
The comparator circuit 80 generates an electric output or error signal having a value or width repre~enting a difference between the value of the output signal of the oxygen sensor 78 and the reference value, or the largeness or smallness of the value of the output ~ignal to the reference value. Thè comparator circuit 80 is electrically connected to the actuator 26 of the mixture forming device 22 to apply the output signal thereto.
The actuator 26 is actuated in accordance with the value of the output signal of the comparator circuit 80, for example, to adjust the ratio of open time and closed time of the valve means of the mixture forming device 22 to adjust the amount of fuel or air fed there- ~' ~5 from or-into for formation of an engine air-fuel mixture to 1049;~48 correct the overnll air-fuel ratio to the de.~ired air-~`uel ratio.
The combir-ation of the fuel tank venting Yystem and the air-fuel ratio control system thu~ far described is operated as follow~:
The evaporated fuel vapour (mainly unburned hydro-carbons) in the fuel tank 30 i9 drawn into the fuel vapour passageway 32 toward the canister 40 by the pressure therein les~ than the pressure in the fuel tank 30. A portion of and/or liquid in the fuel vapour is liquefied and/or separated in the separator 36 and is returned into the fuel tank 30. The remaining fuel vapour is drawn into the chamber 48 of the canister 40 through the passage 32a and the inlet chamber 52 and is absorbed by the absorber 58. Atmospheric air is concurrently drawn into the chamber 48 through the air inlet port 50. Suction from the induction passageway 16 acts on the canister 40 through the pasYage 70 to release the fuel vapour from the absorber 58 and draw a mixture of the fuel vapour and atmospheric air of an amount metered by the flow control valve 60 into the induction passageway 16 through the passage 32bo The mixture of the fuel vapour and air thus drawn is conducted into the combustion chamber through the induction passageway 16 to cause a variation in the nir-fuel ratio of an engine air-fuel mixture and is burned in the combustion chamber together with the en~ine air-fuel mixture to produce engine exhaust gases which is discharged into the exhaust gas passageway 20.
The oxygen sen~or 78 senses the concentration of oxygen present in the engine exhaust gases which con-centration represents the overall air-fuel ratio varied by the fuel vapour and air fed into the combustion chamber. The sensor 78 generates an output signal represents the sensed concentration of oxygen. The comparator circuit 80 compares the value of the output signal of the sensor 78 with the reference ~alue and generates an output signal representing the excess or deficiency of fuel or the deficiency or excess of air when the overall air-fuel ratio is les~ or greater than the desired air-fuel ratio. The actuator 26 is caused by the output signal of the comparator circuit 80 to open the valve means of the mixture forming device 22 to reduce or increase the amount of fuel fed therefrom or to increase or reduce the amount of air fed thereinto to form an engine air-fuel mixture diluted or enriched to the extent that the overall air-fuel ratio is increased or reduced to the desired air-fuel ratio. Thus, the overall air-fuel ratio is maintained at the desired air-fuel ratio irrespective of the amount of the eYaporated fuel VapOUr : ' :' .
- . '~ . . : -fed from the f`uel tank 30 into the combustion chamber.
As a result, the driveability of the engine 10 i~
stabili~.ed and the exhaust gas purifying device 28 exhibits its function best to minimize the contents of air pollutants in engine exhaust gases emitted therefrom.
Although, with a fuel tank venting system which is not combined with an air-fuel ratio control system, it has been necessary to make great efforts in, for example, adjusting a flow control valve to allow the flow of fuel vapour fed into an engine induction pa~sage-way to come as near to a de~ired value as possible, with a fuel tank venting system which is combined with an air-fuel ratio control system as according to the in-vention, it is unnecessary to make ~uch efforts and an advanta$e i9 obtained that means for controlling the flow of fuel vapour can be simplified to, for example, an orifice.
It will be appreciated that the invention provides a combination of a fuel tank venting system and an air-fuel ratio control system which combination controls orcorrects the overall air-fuel ratio varied by evaporated fuel vapour fed from a fuel tank into a combustion chamber of the engine to a desired air-fuel ratio 90 that the evaporated fuel vapour can be fed from the fuel tank into the combustion chamber without causing the _ 14 -deteriotation of the driveability of the engine and reducing the performance, of an exhauYt gas treating device of the engine, of treating engine exhaust gases.
Although the invention has been described as being applied to an engine including a catalytic converter having a ternal catalyst, the invention Carl be applied to an engine including other exhaust gas purifying device such a~ a thermal reactor or a catalytic converter having a reduction or oxidation catalyst. In this in-stance, a desired value of the overall air-fuel ratio is a value at which the exhaust gas treating device exhibits its function or performance best.
:
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A combination of a fuel tank venting system and an air-fuel ratio control system of an internal combustion engine, said fuel tank venting system com-prising a fuel tank for storing liquid fuel to be fed to said engine, and passage means providing fluid com-munication between said fuel tank and an induction passageway of said engine to conduct evaporated fuel vapour from said fuel tank into a combustion chamber of said engine through said induction passageway by suction therein, said air-fuel ratio control system comprising a mixture forming device for providing an air-fuel mixture burned in said combustion chamber, sensing means for sensing the overall air-fuel ratio of all air and fuel fed into said engine, and control means comparing the sensed overall air-fuel ratio with a desired air-fuel ratio and having said mixture forming device form an air-fuel mixture having an air-fuel ratio which makes said overall air-fuel ratio equal to said desired air-fuel ratio when said sensed overall air-fuel ratio is different from said desired air-fuel ratio.
2. A combination as claimed in Claim 1, in which said sensing means comprises a sensor sensing the concentration of a component contained in exhaust gases discharged from said engine to sense said overall air-fuel ratio.
3. A combination as claimed in Claim 1, in which said mixture forming device comprises valve means for controlling the amount of fuel fed from said mixture forming device into air fed by said induction passage-way, and an actuator for operating said valve means, said control means comprises a comparator circuit generating an error signal which represents a difference between said sensed overall air-fuel ration and said desired air-fuel ratio and is applied to said actuator to cause the same to open said valve means to adjust the amount of fuel fed from said mixture forming device to have the same form an air-fuel mixture for correct-ing said overall air-fuel ratio to said desired air-fuel ratio .
A combination as claimed in Claim 1, in which said fuel tank venting system further comprises a flow control valve disposed in said passage means and oper-ated by suction in said induction passageway to meter the flow of said fuel vapour fed into said induction passageway through said passage means to a predetermined value.
5. A combination as claimed in Claim 1, in which said fuel tank venting system comprises a canister disposed in said passage means and containing therein absorption means for absorbing said fuel vapour from said fuel tank.
6. An internal combustion engine comprising a combustion chamber, an induction passageway for feed-ing air into said combustion chamber, a mixture forming device for providing an air-fuel mixture burned in said combustion chamber, an exhaust gas passageway for con-ducting engine exhaust gases, a fuel tank venting system comprising a fuel tank for storing liquid fuel to be fed to said combustion chamber, and passage means providing fluid communication between said fuel tank and said induction passageway for conducting evaporated fuel vapour from said fuel tank thereinto, and an air-fuel ratio control system comprising sensing means for sensing the overall air-fuel ratio of all air and fuel fed for formation of said engine exhaust gases in said exhaust gas passageway at a certain position, and control means for comparing the sensed overall air-fuel ratio with a desired air-fuel ratio and for, when said sensed overall air-fuel ratio is different from said desired air-fuel ratio, causing said mixture forming device to form an air-fuel mixture having an air-fuel ratio which makes said overall air-fuel ratio equal to said desired air-fuel ratio.
7. An internal combustion engine as claimed in Claim 6, in which said sensing means comprises a sensor located in said exhaust gas passageway at said certain position and sensing the concentration of a component contained in said engine exhaust gases to sense said overall air-fuel ratio.
8. An internal combustion engine as claimed in Claim 6, in which said mixture forming device comprises valve means for adjusting the amount of fuel fed from said mixture forming device into air fed by said induction passageway, and an actuator for operating said valve means, and in which said control means com-prises a comparator circuit for generating an error signal which represents a difference between said sensed overall air-fuel ratio and said desired air-fuel ratio and is applied to said actuator to cause the same to open said valve means to adjust the amount of said fuel fed from said mixture forming device to cause the same to form an air-fuel mixture for correcting said overall air-fuel ratio to said desired air-fuel ratio.
9. An internal combustion engine as claimed in Claim 6, in which said mixture forming device comprises valve means for adjusting the amount of air fed into said mixture forming device for mixing with fuel fed therefrom into air fed by said induction passageway, and an actuator for operating said valve means, and in which said control means, comprises a comparator circuit for generating an error signal which represents a difference between said sensed overall air-fuel ratio and said desired air-fuel ratio and is applied to said actuator to cause the same to open said valve means to adjust the amount of said air fed into said mixture forming device to cause the same to form an air-fuel mixture for correcting said overall air-fuel ratio to said desired air-fuel ratio.
10. An internal combustion engine as claimed in Claim 6, in which said fuel tank venting system further comprises a flow control valve disposed in said passage means and operated by suction in said induction passage-way to meter the flow of said fuel vapour fed thereinto to a predetermined value.
11. An internal combustion engine as claimed in Claim 10, in which said fuel tank venting system comprises a canister disposed in said passage means at a position upstream of said flow control valve and containing absorption means by which said fuel vapour from said fuel tank is absorbed and from which the absorbed fuel vapour is released by suction in said induction passageway.
12. An internal combustion engine as claimed in Claim 6, further comprising an exhaust gas catalytic converter located in said exhaust gas passageway at a position downstream of said certain position and containing a ternary catalyst which concurrently catalytically promotes both oxidation of hydrocarbons and carbon monoxide present in Raid engine exhaust gases and reduction of nitrogen oxides present in said engine exhaust gases, in which said desired air-fuel ratio is a stoichiometric air-fuel ratio.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3577775A JPS51110130A (en) | 1975-03-25 | 1975-03-25 | Nainenkikanno taikiosenboshisochi |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1049348A true CA1049348A (en) | 1979-02-27 |
Family
ID=12451311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA248,620A Expired CA1049348A (en) | 1975-03-25 | 1976-03-24 | Combination of a fuel tank venting system and an air-fuel ratio control system of an internal combustion engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS51110130A (en) |
| CA (1) | CA1049348A (en) |
| DE (1) | DE2612300A1 (en) |
| GB (1) | GB1530511A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5922066B2 (en) * | 1979-03-08 | 1984-05-24 | 日産自動車株式会社 | Evaporated fuel processing device for internal combustion engine |
| JPS6033316Y2 (en) * | 1980-09-16 | 1985-10-04 | トヨタ自動車株式会社 | Fuel vapor purge device |
| DE3124956C1 (en) * | 1981-06-25 | 1983-01-27 | Bayerische Motoren Werke AG, 8000 München | System for venting the evaporation gases from the fuel tank of a motor vehicle |
| JPS6176734A (en) * | 1984-09-19 | 1986-04-19 | Mazda Motor Corp | Atmospheric pollution prevention device of engine |
| DE3502573C3 (en) * | 1985-01-26 | 2002-04-25 | Bosch Gmbh Robert | Device for venting fuel tanks |
| DE3519292A1 (en) * | 1985-05-30 | 1986-12-04 | Robert Bosch Gmbh, 7000 Stuttgart | DISPENSING SYSTEM FOR INITIATING VAPORIZED FUEL INTO AN INTERNAL COMBUSTION ENGINE |
| JPH073211B2 (en) * | 1985-07-17 | 1995-01-18 | 日本電装株式会社 | Fuel evaporative emission control device |
| JPH0726573B2 (en) * | 1985-12-11 | 1995-03-29 | 富士重工業株式会社 | Air-fuel ratio controller for automobile engine |
| DE4430971A1 (en) | 1994-08-31 | 1996-03-07 | Bayerische Motoren Werke Ag | Method and device for supplying fuel vapor into an intake manifold of an internal combustion engine in motor vehicles |
| US8632051B2 (en) | 2011-10-14 | 2014-01-21 | Firma SVM Schultz Verwaltungs-GmbH & Co. KB | Solenoid |
-
1975
- 1975-03-25 JP JP3577775A patent/JPS51110130A/en active Pending
-
1976
- 1976-03-16 GB GB1044976A patent/GB1530511A/en not_active Expired
- 1976-03-23 DE DE19762612300 patent/DE2612300A1/en not_active Withdrawn
- 1976-03-24 CA CA248,620A patent/CA1049348A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1530511A (en) | 1978-11-01 |
| JPS51110130A (en) | 1976-09-29 |
| DE2612300A1 (en) | 1976-10-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5080078A (en) | Fuel vapor recovery control system | |
| US4075834A (en) | Air-fuel ratio control adjusting system in an internal combustion engine | |
| CA1049348A (en) | Combination of a fuel tank venting system and an air-fuel ratio control system of an internal combustion engine | |
| JP2533350Y2 (en) | Fuel vapor emission suppression device for internal combustion engine | |
| CN101023260A (en) | Low fuel consumption, low pollution combustion system for providing a fuel and oxygen mixture to a vehicle engine | |
| US4149376A (en) | Internal combustion engine equipped with exhaust gas purifying device | |
| JPH07127503A (en) | Exhaust gas purification device for internal combustion engine | |
| US4065920A (en) | Two barrel carburetor | |
| US4246752A (en) | Turbocharged engine control | |
| US4098079A (en) | Secondary air feed control device of an internal combustion engine | |
| US4123903A (en) | Deceleration control system | |
| JPH07253049A (en) | Fuel supply device for gas fuel engine | |
| JPH04203467A (en) | Vapored fuel control device of engine | |
| CA1044543A (en) | Combination of a crankcase ventilation system and an air-fuel ratio control system for an engine | |
| US4051674A (en) | Multicylinder internal combustion engine | |
| JPS597723A (en) | Exhaust gas purifier of internal-combustion engine | |
| JPS59165852A (en) | Fuel supply device for gas engine | |
| JPS61258963A (en) | Fuel vaporization suppressor for internal-combustion engine | |
| JPH0248655Y2 (en) | ||
| JPS6429665A (en) | Fuel feed device for alcohol fuel engine | |
| JPH0330618Y2 (en) | ||
| JPH0788333A (en) | Exhaust gas purification device for internal combustion engine | |
| JPH05263629A (en) | Evaporative gas purification device for lean burn internal combustion engine | |
| JPH05332207A (en) | Air-fuel ratio controller for internal combustion engine | |
| JP3500641B2 (en) | Air-fuel ratio control device for internal combustion engine |