CA1044543A - Combination of a crankcase ventilation system and an air-fuel ratio control system for an engine - Google Patents
Combination of a crankcase ventilation system and an air-fuel ratio control system for an engineInfo
- Publication number
- CA1044543A CA1044543A CA248,749A CA248749A CA1044543A CA 1044543 A CA1044543 A CA 1044543A CA 248749 A CA248749 A CA 248749A CA 1044543 A CA1044543 A CA 1044543A
- Authority
- CA
- Canada
- Prior art keywords
- air
- fuel ratio
- engine
- fuel
- blow
- 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
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
- F02D35/0046—Controlling fuel supply
-
- 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
- F02M25/06—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding lubricant vapours
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Lubrication Details And Ventilation Of Internal Combustion Engines (AREA)
- Exhaust Gas After Treatment (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
Abstract
A system for restoring blow-by gases in the crankcase into a combustion chamber of an engine is combined with an air-fuel ratio control system in such a manner as to correct the overall air-fuel ratio varied by the blow-by gases restored into the combustion chamber to a desired air-fuel ratio.
Description
10~543 The present invention relate~ generally to a system for co~trolling the air-fuel ratio of an air-fuel mixture burned in an internal combu~tion engine or the overall air-fuel ratio of total amounts of air and fuel fed into the engine to a desired air-fuel ratio and particularly to an alr-fuel ratio control ay~tem combined with a ~ystem for re~toring cr,ankcaJe blow-by gase~ into a combu~tion chamber of the engine in such a manner aJ
to correct the mixture air-fuel ratio or the overall air-fuel ratio varied by the blow-by gase~ restored to a desired air-fuel ratio.
As is well known in the art, it is a basic require-ment for reducing the content~ of air pollutants in exhauJt gRse~ di~charged from an engine to accurately control the air-fuel ratio of an air-fuel mixture for the engine to a de~ired value. Particularly, when the engine i8 provided wlth, for ex~mple, ~ catalytic converter includlng a ternal catalyst which concurrently catalytically promotes both oxidation of noxious com-zO ponents such as hydrocarbons (HC) and carbon monoxide(CO) in engine exhaust gases and reduction of o~ther noxious component such as nitrogen oxides (NOx) therein to render them harmless, it is necessary to maintain the total or overall air-fuel ratio till before the catalytic converter (the air-fuel ratio by weight of
to correct the mixture air-fuel ratio or the overall air-fuel ratio varied by the blow-by gase~ restored to a desired air-fuel ratio.
As is well known in the art, it is a basic require-ment for reducing the content~ of air pollutants in exhauJt gRse~ di~charged from an engine to accurately control the air-fuel ratio of an air-fuel mixture for the engine to a de~ired value. Particularly, when the engine i8 provided wlth, for ex~mple, ~ catalytic converter includlng a ternal catalyst which concurrently catalytically promotes both oxidation of noxious com-zO ponents such as hydrocarbons (HC) and carbon monoxide(CO) in engine exhaust gases and reduction of o~ther noxious component such as nitrogen oxides (NOx) therein to render them harmless, it is necessary to maintain the total or overall air-fuel ratio till before the catalytic converter (the air-fuel ratio by weight of
- 2 -'.'.~- ; ~ -104~S43 the quantities of all air and fuel fed into the engine for formation of the engine exhaust ga~e~ fed to the catalytic converter)at A Jtoichiometric a$r-fuel ratio.
This i~ because of the ternal catalyst exhibiting the above-mentioned function most effectively when the overall air-fuel ratio 18 maintained at the atoichio-metric air-fuel ratio. Simil~rly.when the en8ine i~
provided with other exhaust ga~ purifying device such as a thermal reactor or n catalytic reactor having a reduction catalyJt or an oxidation catalyst, it i~
necessary to maintain the overall air-fuel ratio at a specific air-fuel ratio.to exhibit its function best.
As an expedient for controlling the overall air-fuel ratlo to a deJired value, there iJ proposed a syJtem compri~ing a Aen~Or ~en~ing the concentratlon of a component contained in en$ine exhau~t 8a~es and control means controlling in accordance with the ~ensed con-centration of the component valve mean~ of a mixture forming device to adjuJt the amount of fuel fed there-zo from to thereby control the overall air-fuel ratio to the desired value.
Meanwhile, an engine is provided with a ~ystem for restoring blow-by gases in the crankcase into a combustion chamber of the engine to prevent engine lubricating oil from being deteriorated. The amount ,3 10~543 and air-fuel ratio of blow-by gase~ escaping from the combustion chamber into the crankcase are varled in accordance with operating conditions of the engine.
A tlow control valve iJ provided to control the flow of blow-by gase~ restored into the combustion chamber to a desired or predetermined ratio to the flow of air ed lnto the combustion chamber. This i~ to prevent the overall air-fuel ratio from being varied by blow-by ga~es restored into the combustion chamber to cauJe increasea in the contents of air pollutants in engine exhaust gase~ and deterioration of the driveability of the engine. Howe~er, it has been impossible to accu-rately control the flow of blow-by gaJes restored to a desired value to prevent the overall air-fuel ratio J 15 from being varied by the blow-by ga~es re~tored.
It is, therefore~ an object of the invention to provide a combination of an air-fuel ratio control ~y.q1;em and a crankca~qe blow-by ga~ re~toring sy~tem for an internal combustion engine by which combination the overall air-fuel ratio is prevented from being varied by blow-by gase~ restored into the combustion chamber.
Thi~ and other objects and advantage~ of the invention will become more apparent from the following detailed description taken in conjunction with the ,,s .
.
:`
' , ' , 1~14~$43 ~ ~
accompanying drawings in which:
Fig. 1 i~ a ~chematic view of a preferred embodi-ment of a combination according to the invention of a crankca~e blow-by ga~ re~toring sy~tem and an air-fuel ratio control ~y~tem; and Fig. 2 iY a graphic repreJentation of a flow characteri~tic~ of a flow control valve forming part of the crankca~e blow-by ga~ re~toring ~y~tem ~hown ln Flg. 1.
Referring to the drawing, there i~ shown a com-binatlon according to the invention of an air-fuel ratio control ~y~tem 10 with a crankca~e ventilation or blow-by gas re~toring sy~tem 12 and an internal combu~tion engine 14. The engine 14 is shown to compri~e a combustion chamber 16, a crankca~e 18 having therein the combu~tion chamber 16 and into which blow-by gases e~cape therefrom, and intake and exh~u~t sy~tems 20 and 22. The intake ~y~tem 20 includeY an induction pa~ageway 24 communicating with the ambient atmo~phere through an air cleaner 26 and opening into the combu~tion chamber 16 through an intake port (no numeral) to-feed air or an air-fuel mixture into the combu~tion chamber 16, and an air-fuel mixture forming device or a fuel supply device 28 for feeding fuel into air fed by the , ' - ,,.: ~
' 10~543 induction pas~ageway 24 to provide an air-fuel mixture f`or `illing the combu~tion chamber 16. A carburetor i8 employed as the mixture forming device 28 in the embodiment. A fuel injection device or injec~or may he employed in place of the carburetor. The mixture generating device 28 include~ valve meanY (not shown) ~ucll a~ a valve of nn on-off typ,e disposed in a fuel or air bleed passage in the case of a constant choke carburetor or in a fuel or air bypass passage formed around a throttle valve in the case of a variable choke carburetor, or a fuel injection valve in the case of the fuel injector. The valve means of the mixture forming device 28 i~ operated by an actuator 5~ such as a solenoid, a servo motor or a diaphragm.
The exhaust Jy~tem 22 includes an exhaust gas pa~sageway 32 extending from an exhaust port (not .qhown) of the combustlon chamber 16 nnd vented to the nmbient atmoJphere, and an exhaust ga~ treating or purifylng device 34 such as, for example, an exhaust gas catalytic converter which is located in the ex-haust gas passageway 32. The catalytic converter 34 : may contain therein a ternary or three-way catalyst (not shown) which serves to concurrently catalytically promote both oxidation of one portion of air pollutants a5 ~ucù as hydrocarbon~ (HC) and carboD mono~ide (C0) 104~543 contained in exhaust ga~eY discharged from the engine 14 and reduction of another portion of the air pollutants ~uch as nitrogen oxide~ (NOx) to render these noxious componentJ harmleJs. The exhau~t gas purifying device 34 may include A secondary air supply device (not ~hown) for feeding ~econdary alr lnto engine exhaust gase~ fed to the exhauat purifying device 34 to assi~t and promote reactlon or combuYtion of burnable noxiou~ componentY
oi the engine exhAust gaJes therein.
The crankca~e ventilation Jystem 12 compriqes pa~sage meanJ 36 which iJ connected at one end to the crankca~e 18 and at the other end to the induction passageway 24 at a position 37 downstream of a throttle valve 38 of the carburetor 28 or to an intake manlfold 40 forming part of the induction paJsageway Z4 and which restores blow-by gaJ or a mixture Or blow-by gases a~d ventilation air from the crankcas0 18 there-into. Passage means 42 i~ provided which is connected at one end to a rocker cover 44 of the crankcase 18 and at the other end to a clean slde 46 of the air cleaner 26. The paqqage means 42 openJ into the air cleaner 26 through an oil filter 48 and restores blow-by gases or a blow-by gas and ventilation alr mixture into the induction pasJageway 24 through the air cleaner 26. A flow control valve 50 i~ disposed in :
10445~3 the pas~age means 36 to control or meter the flow of blow-by gaseY fed into the induction paJsageway 24 therethrough to a deYired or predetermined ratio to the flow of air drawn into the combuJtion chamber 16 through the induction pa~ageway 24. The flow control valve 50 include~ a valve chamber 52 into which pas~age mean~ 36a and 36b open and in wh,ich the control valve 50 i~ movably located to divide the interior of the chamber 5~ into up~tream and downstream portion~ 54 and 56.
The valve chamber 52 provides an annular clearance between its lnternal wall and the control valve 50 to provide communicatlon between the up~tream and down-~tream portions 54 and 56. The control valve 50 ha~ a projection or needle 58 extending into and tapering to the pas~age means 36b. The projectlon 58 reduces or increa~e~ the cross ~ectional area of the pa~age means 36b when the control valve 50 moves ln re~pon~e to increa~e or decrease in the induction pa~sageway vacuum. A compre~ion spring 60 is located in the downYtream portion 56 to urge the control valve 50 toward the pa~age means 36a. The control valve 50 also ha~ a projection 62 extending toward the pa~age mean~ 36a. The projection 62 clo~es the pa~age meanY
36a when the control valve 50 move~ into the extreme rightward po~ition in response to a decreaYe in the , . .
lQ44543 induction passageway vacuum. The control valve 50 has a flow characteri~tics that the flow of fluid i~
increased when the induction passageway vacuum i9 relatively low and is reduced to a constant value when the induction pasJageway vacuum 1J relatively high, a~ shown in Fig. 2 of the drawingJ. The crank-CAse 18 may be provided with a ventilation alr inlet port (not Nhown) communicating with the ambient atmo~phere through a check valve which i~ opened by the induction paJ~ageway vacuum or an air cleaner vacuum to permit atmo~pheric air flow from the atmosphere into the crankcase 18 and iJ clo~ed to inhibit blow-by gas flow from the crankca~e 18 to the atmo~phere.
The air-fuel ratio control system 10 serves to control or correct to a desired air-fuel ratio the - air-fuel ratio of an air-fuel mixture burned in the combu~tion chamber 16 or, ~hen ffecondary air is fed , lnto engine exhaust gases the total air-fuel ratio - of engine exhaust ga~es in the exhaust gas pa~sageway 20 32 at a po~ition immediately upJtream of the exhaust gas treating device 34, that is, the air-fuel ratio by weight of total amounts of air and fuel fed for or having participated in formation of the engine exhaust gases fed to the exhaust gas purifying device 34. The air-fuel ratio control sy~tem 10 comprises sensing 10'1459~3 mean~ 64 located in the exhaust gas passageway 32 at A location upstream of the exhaust gaJ purifying device 34 and sensing the concentration of a component such a~
oxygen (2)' carbon monoxide (C0), carbon dioxide~ (C0z), hydrocarbon~ (HC), or nitrogen oxidea (NOx) contained in engine exhaust gaaea whlch concentration is cloJely related to or representa the air,-fuel ratio of an air-fuel mlxture burned in the combustion chamber 16 or the total air-fuel ratio. An oxygen ~ensor is employed as the senaing means 64 in the embodiment and generates an electric output signal having a magnitude representing the sensed concentration of oxy~en. The oxygen sen~or 64 i8 electrically connected to a control or comparator circuit 66 which receivea the output signal thereof.
The control circuit 66 compare~ the magnitude of the output signal of the oxygen sen~or 64 with a desired reference value which repre~ent~ the de~ired ~lr-fuel ratio which ia a stoichiometric nir-fuel ratio when the exhaust gaJ treating device 34 i~ a catalytic reactor including a ternary cataly~t. The control circuit 66 generates an electric output signal having a magnitude or pulse width representing a differential value between the magnitude of the output ~ignal of the oxygen ~ensor 64 and the reference value, or the largeness or smallness of the magnitude of the output lQ~543 gignal of the oxygen sensor 64 to the reference value.
The control circuit 66 is electrically connected to the actuator 68 to apply the output ~ignal thereto.
The actuator 68 i~ actuated by the output eignal of -~
the control circuit 66 a period of time corresponding to the magnltude or pul~e width of the output signal to increase and reduce the ratio of open time and clo~ed time of the valve mean~ of the mixture forming devlce 28 to incresse and reduce the amount of fuel ]o 1'ed for forming an air-fuel mixture for the engine 14 to converge the air-fuel ratio of the air-fuel mixture ` into the de~ired air-fuel ratio.
The combination Or the air-fuel ratio control ~y~tem 10 with the blow-by gaJ restoring system 12 and the engine 14 thua far dcscribed is operated as follows: :
;; The crankcase 18 is fed with blow~by ga~e~ e~cap-ing from the combustion chamber 16 during operations of the engine 14. The amount of blow-by ga~es thus fed increases and reduces in accordance with an increaYe and decrease in the load of the engine 14.
The air-fuel ratio of the blow-by gases varies in accordance with operating conditions of the engine 14.
Atmo4pheric air is drawn from the air cleaner 26 - 25 into the crankcase 18 through the pas~age mean~ 42 and :' .
.
~ 104~5~3 the blow-by ga~es ln the crankcase 18 are drawn together with the air by the induction p~a~age~ay or intake manifold vacuum into the induction pA~sageway 2ll through the pas~age mean~ 36 and the flow control valve 50. When the induction pas~a~eway vacuum i~
relatively high, the flow control valve 50 i9 moved ln oppo~ition to the force of the aprlng 60 to reduce the cros~ ~ectlonal area of the pa~age meanJ 36b and accordingly reduce the flow of blow-by gases passing therethrough. On the contrary, when the induction passageway vacuum is relatively low, the flow control valve 50 is moved to increase the cross sectional area of the passage meana 36b and accordingly reduce the flow of blow-by gasea pas~ing therethrough. As a reYult, the amount of blow-by gnses drawn into the inductlon pa~ageway 24 i~ approximately maintained at a desired or predetermined ratio to the amount of air drawn lnto the combu~tlon chamber 16.
When the lnductlon pa~aageway vacuum is extremely high or low the flow control valve 50 i~ moved into a position to close the pa~age means 36 to reduce the flow of blow-by gases restored into the induction passageway 24 to zero. When the induction pa~sage~ay vacuum i9 extremely low, the engine 14 runs under a high speed and high load condition in which the throttle ., .
- 12 _ .
valve 3~ i~ in its fully open po~ition and accordingly the induction pas~ageway VACUUm approaches the atmo~-pheric pressure. In thi~ instance, the blow-by gases in the crankcase 18 are drawn from the rocker cover 44 i~to the air cleaner 26 through the pas~ag0 means 42 and the oil filter 48 by a vacuum produced in the air cLeaner 26 by a large quantity,of air drawn into the induction pa~ageway Z~ at a high ~peed.
The blow-by gase~ thu~ fed into the induction pa~sageway 24 cau~e variatlon~ in the air-fuel ratio of an air-fuel mixture burned in the combu~tion cham-ber 16 and accordingly the overall air-fuel ratio, since the flow of the blow-by gaJes restored cannot be accurately metered in fact and the air-fuel ratio f the blow-by ga~e~ varie~.
The air-fuel mixture burned in the combustion chamber 16 produce~ engine exhau~t gn~e~ which are di~charged into the exhau~t ga~ pas~ageway 32. The oxygen sensor 64 sense~ the concentration of oxygen in the engine exhauYt gase~ which concentration repre~ents the variation~ in the mixture air-fuel ratio or the o~erall air-fuel ratio to generate an output *ignal repre~enting the ~ensed concentration of oxygen. When the total air-fuel ratio iA lower than the desired air-fuel ratio~ the control circuit ~044543 66 compare~ the magnitude of the output sigrlal of the oxygen sensor 64 with the reference value and generates an output signal fGr causing the mixture forming device Z8 to form an air-fuel mixture diluted to the extent th~t the total air-fuel ratlo is increased to the de~ired air-fuel ratio. The actUAtor 68 i8 energized hy the output Hlgnal of the con~rol circuit 66 to open the valve mean~ of the mixture forming device 28 a period of time corresponding to the output signal to reduce the amount of fuel fed by the mixture forming device 28 to increase the total air-fuel ratio to the deqired air-fuel ratio. On the contrary, when the total air-fuel ratio is higher than the desired air-; fuel ratio, the control circuit 66 generate4 an output 15 signal for cauqing the mixture forming device 28 to f'orm an air-fuel mixture enriched to the extent that the total air-fuel ratio ls reduced to the desired air-fuel ratio. The output signal of the control circuit 66 causes the actuator 68 to open the valve ZO means of the mixture forming device 28 a period of time to increase the amount of fuel fed by the mixture forming device 28 to reduce the total air-fuel ratio 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 blow-by gases ~Q~5~;~
restored into the combuYtion chamber 16 BO that the ex}-aust ga~ purifying device 34 display~ its function best to minimize the content~ of sir pollutants in engine exhaust gases and the operational performance of the engine iJ ~tabillzed.
Although with a conventional crankcase blow-by ga~ re~toring ~yJtem whlch 1~ not comblned wlth an air-fuel ratio control ~ystem, it ha~ been nece~sary to make great efforts in adjusting a flow control In valve to meter the flow of re~tored blow-by ga~e~ to a deYired value and in adju~ting a carburetor or fuel injector to make changeJ in the overall air-fuel ratio by restored blow-by gase~ a~ little a~ posYible, with a crankca~e blow-by gas re~toring sy~tem combined with an air-fuel ratio control system as according to the invention it i~ unnece~sary to make such effortY and a blow-by ga~ flow control valve can be merely replaced by an ori~ice.
It will be appreciated that the invention provides n combination of a crankca~e blow-by gas restoring ~-system and an air-fuel ratio control system which com-bination corrects the overall air-fuel ratio varied by blow-by gase~ restored into a combustion chamber of an engine to a desired air-fuel ratio 80 that an exhaust gas treating device of the engine exhibit its function .
: .: , .
1~4~5~3 be~t, the driveability of the engine i9 ~tabilized, and flow control mean~ of the crankca~e blow-by gas re~toring sy~tem i~ con~iderably simplfied or i9 diApenAed with.
Although the invention hns been described as being applled to an engine includlng a catalytlc converter havlng a ternal cata~yst, the inventiGn can be applied to an englne including other exhaust gas purifying device such n~ A reactor or a catalytic converter having a reduction or oxidation catalyst.
In this in~tance, a de~ired value of the overall air-fuel ratio i~ a value nt which the exhaust gas purifying devlce exhibit~ it~ function best.
This i~ because of the ternal catalyst exhibiting the above-mentioned function most effectively when the overall air-fuel ratio 18 maintained at the atoichio-metric air-fuel ratio. Simil~rly.when the en8ine i~
provided with other exhaust ga~ purifying device such as a thermal reactor or n catalytic reactor having a reduction catalyJt or an oxidation catalyst, it i~
necessary to maintain the overall air-fuel ratio at a specific air-fuel ratio.to exhibit its function best.
As an expedient for controlling the overall air-fuel ratlo to a deJired value, there iJ proposed a syJtem compri~ing a Aen~Or ~en~ing the concentratlon of a component contained in en$ine exhau~t 8a~es and control means controlling in accordance with the ~ensed con-centration of the component valve mean~ of a mixture forming device to adjuJt the amount of fuel fed there-zo from to thereby control the overall air-fuel ratio to the desired value.
Meanwhile, an engine is provided with a ~ystem for restoring blow-by gases in the crankcase into a combustion chamber of the engine to prevent engine lubricating oil from being deteriorated. The amount ,3 10~543 and air-fuel ratio of blow-by gase~ escaping from the combustion chamber into the crankcase are varled in accordance with operating conditions of the engine.
A tlow control valve iJ provided to control the flow of blow-by gase~ restored into the combustion chamber to a desired or predetermined ratio to the flow of air ed lnto the combustion chamber. This i~ to prevent the overall air-fuel ratio from being varied by blow-by ga~es restored into the combustion chamber to cauJe increasea in the contents of air pollutants in engine exhaust gase~ and deterioration of the driveability of the engine. Howe~er, it has been impossible to accu-rately control the flow of blow-by gaJes restored to a desired value to prevent the overall air-fuel ratio J 15 from being varied by the blow-by ga~es re~tored.
It is, therefore~ an object of the invention to provide a combination of an air-fuel ratio control ~y.q1;em and a crankca~qe blow-by ga~ re~toring sy~tem for an internal combustion engine by which combination the overall air-fuel ratio is prevented from being varied by blow-by gase~ restored into the combustion chamber.
Thi~ and other objects and advantage~ of the invention will become more apparent from the following detailed description taken in conjunction with the ,,s .
.
:`
' , ' , 1~14~$43 ~ ~
accompanying drawings in which:
Fig. 1 i~ a ~chematic view of a preferred embodi-ment of a combination according to the invention of a crankca~e blow-by ga~ re~toring sy~tem and an air-fuel ratio control ~y~tem; and Fig. 2 iY a graphic repreJentation of a flow characteri~tic~ of a flow control valve forming part of the crankca~e blow-by ga~ re~toring ~y~tem ~hown ln Flg. 1.
Referring to the drawing, there i~ shown a com-binatlon according to the invention of an air-fuel ratio control ~y~tem 10 with a crankca~e ventilation or blow-by gas re~toring sy~tem 12 and an internal combu~tion engine 14. The engine 14 is shown to compri~e a combustion chamber 16, a crankca~e 18 having therein the combu~tion chamber 16 and into which blow-by gases e~cape therefrom, and intake and exh~u~t sy~tems 20 and 22. The intake ~y~tem 20 includeY an induction pa~ageway 24 communicating with the ambient atmo~phere through an air cleaner 26 and opening into the combu~tion chamber 16 through an intake port (no numeral) to-feed air or an air-fuel mixture into the combu~tion chamber 16, and an air-fuel mixture forming device or a fuel supply device 28 for feeding fuel into air fed by the , ' - ,,.: ~
' 10~543 induction pas~ageway 24 to provide an air-fuel mixture f`or `illing the combu~tion chamber 16. A carburetor i8 employed as the mixture forming device 28 in the embodiment. A fuel injection device or injec~or may he employed in place of the carburetor. The mixture generating device 28 include~ valve meanY (not shown) ~ucll a~ a valve of nn on-off typ,e disposed in a fuel or air bleed passage in the case of a constant choke carburetor or in a fuel or air bypass passage formed around a throttle valve in the case of a variable choke carburetor, or a fuel injection valve in the case of the fuel injector. The valve means of the mixture forming device 28 i~ operated by an actuator 5~ such as a solenoid, a servo motor or a diaphragm.
The exhaust Jy~tem 22 includes an exhaust gas pa~sageway 32 extending from an exhaust port (not .qhown) of the combustlon chamber 16 nnd vented to the nmbient atmoJphere, and an exhaust ga~ treating or purifylng device 34 such as, for example, an exhaust gas catalytic converter which is located in the ex-haust gas passageway 32. The catalytic converter 34 : may contain therein a ternary or three-way catalyst (not shown) which serves to concurrently catalytically promote both oxidation of one portion of air pollutants a5 ~ucù as hydrocarbon~ (HC) and carboD mono~ide (C0) 104~543 contained in exhaust ga~eY discharged from the engine 14 and reduction of another portion of the air pollutants ~uch as nitrogen oxide~ (NOx) to render these noxious componentJ harmleJs. The exhau~t gas purifying device 34 may include A secondary air supply device (not ~hown) for feeding ~econdary alr lnto engine exhaust gase~ fed to the exhauat purifying device 34 to assi~t and promote reactlon or combuYtion of burnable noxiou~ componentY
oi the engine exhAust gaJes therein.
The crankca~e ventilation Jystem 12 compriqes pa~sage meanJ 36 which iJ connected at one end to the crankca~e 18 and at the other end to the induction passageway 24 at a position 37 downstream of a throttle valve 38 of the carburetor 28 or to an intake manlfold 40 forming part of the induction paJsageway Z4 and which restores blow-by gaJ or a mixture Or blow-by gases a~d ventilation air from the crankcas0 18 there-into. Passage means 42 i~ provided which is connected at one end to a rocker cover 44 of the crankcase 18 and at the other end to a clean slde 46 of the air cleaner 26. The paqqage means 42 openJ into the air cleaner 26 through an oil filter 48 and restores blow-by gases or a blow-by gas and ventilation alr mixture into the induction pasJageway 24 through the air cleaner 26. A flow control valve 50 i~ disposed in :
10445~3 the pas~age means 36 to control or meter the flow of blow-by gaseY fed into the induction paJsageway 24 therethrough to a deYired or predetermined ratio to the flow of air drawn into the combuJtion chamber 16 through the induction pa~ageway 24. The flow control valve 50 include~ a valve chamber 52 into which pas~age mean~ 36a and 36b open and in wh,ich the control valve 50 i~ movably located to divide the interior of the chamber 5~ into up~tream and downstream portion~ 54 and 56.
The valve chamber 52 provides an annular clearance between its lnternal wall and the control valve 50 to provide communicatlon between the up~tream and down-~tream portions 54 and 56. The control valve 50 ha~ a projection or needle 58 extending into and tapering to the pas~age means 36b. The projectlon 58 reduces or increa~e~ the cross ~ectional area of the pa~age means 36b when the control valve 50 moves ln re~pon~e to increa~e or decrease in the induction pa~sageway vacuum. A compre~ion spring 60 is located in the downYtream portion 56 to urge the control valve 50 toward the pa~age means 36a. The control valve 50 also ha~ a projection 62 extending toward the pa~age mean~ 36a. The projection 62 clo~es the pa~age meanY
36a when the control valve 50 move~ into the extreme rightward po~ition in response to a decreaYe in the , . .
lQ44543 induction passageway vacuum. The control valve 50 has a flow characteri~tics that the flow of fluid i~
increased when the induction passageway vacuum i9 relatively low and is reduced to a constant value when the induction pasJageway vacuum 1J relatively high, a~ shown in Fig. 2 of the drawingJ. The crank-CAse 18 may be provided with a ventilation alr inlet port (not Nhown) communicating with the ambient atmo~phere through a check valve which i~ opened by the induction paJ~ageway vacuum or an air cleaner vacuum to permit atmo~pheric air flow from the atmosphere into the crankcase 18 and iJ clo~ed to inhibit blow-by gas flow from the crankca~e 18 to the atmo~phere.
The air-fuel ratio control system 10 serves to control or correct to a desired air-fuel ratio the - air-fuel ratio of an air-fuel mixture burned in the combu~tion chamber 16 or, ~hen ffecondary air is fed , lnto engine exhaust gases the total air-fuel ratio - of engine exhaust ga~es in the exhaust gas pa~sageway 20 32 at a po~ition immediately upJtream of the exhaust gas treating device 34, that is, the air-fuel ratio by weight of total amounts of air and fuel fed for or having participated in formation of the engine exhaust gases fed to the exhaust gas purifying device 34. The air-fuel ratio control sy~tem 10 comprises sensing 10'1459~3 mean~ 64 located in the exhaust gas passageway 32 at A location upstream of the exhaust gaJ purifying device 34 and sensing the concentration of a component such a~
oxygen (2)' carbon monoxide (C0), carbon dioxide~ (C0z), hydrocarbon~ (HC), or nitrogen oxidea (NOx) contained in engine exhaust gaaea whlch concentration is cloJely related to or representa the air,-fuel ratio of an air-fuel mlxture burned in the combustion chamber 16 or the total air-fuel ratio. An oxygen ~ensor is employed as the senaing means 64 in the embodiment and generates an electric output signal having a magnitude representing the sensed concentration of oxy~en. The oxygen sen~or 64 i8 electrically connected to a control or comparator circuit 66 which receivea the output signal thereof.
The control circuit 66 compare~ the magnitude of the output signal of the oxygen sen~or 64 with a desired reference value which repre~ent~ the de~ired ~lr-fuel ratio which ia a stoichiometric nir-fuel ratio when the exhaust gaJ treating device 34 i~ a catalytic reactor including a ternary cataly~t. The control circuit 66 generates an electric output signal having a magnitude or pulse width representing a differential value between the magnitude of the output ~ignal of the oxygen ~ensor 64 and the reference value, or the largeness or smallness of the magnitude of the output lQ~543 gignal of the oxygen sensor 64 to the reference value.
The control circuit 66 is electrically connected to the actuator 68 to apply the output ~ignal thereto.
The actuator 68 i~ actuated by the output eignal of -~
the control circuit 66 a period of time corresponding to the magnltude or pul~e width of the output signal to increase and reduce the ratio of open time and clo~ed time of the valve mean~ of the mixture forming devlce 28 to incresse and reduce the amount of fuel ]o 1'ed for forming an air-fuel mixture for the engine 14 to converge the air-fuel ratio of the air-fuel mixture ` into the de~ired air-fuel ratio.
The combination Or the air-fuel ratio control ~y~tem 10 with the blow-by gaJ restoring system 12 and the engine 14 thua far dcscribed is operated as follows: :
;; The crankcase 18 is fed with blow~by ga~e~ e~cap-ing from the combustion chamber 16 during operations of the engine 14. The amount of blow-by ga~es thus fed increases and reduces in accordance with an increaYe and decrease in the load of the engine 14.
The air-fuel ratio of the blow-by gases varies in accordance with operating conditions of the engine 14.
Atmo4pheric air is drawn from the air cleaner 26 - 25 into the crankcase 18 through the pas~age mean~ 42 and :' .
.
~ 104~5~3 the blow-by ga~es ln the crankcase 18 are drawn together with the air by the induction p~a~age~ay or intake manifold vacuum into the induction pA~sageway 2ll through the pas~age mean~ 36 and the flow control valve 50. When the induction pas~a~eway vacuum i~
relatively high, the flow control valve 50 i9 moved ln oppo~ition to the force of the aprlng 60 to reduce the cros~ ~ectlonal area of the pa~age meanJ 36b and accordingly reduce the flow of blow-by gases passing therethrough. On the contrary, when the induction passageway vacuum is relatively low, the flow control valve 50 is moved to increase the cross sectional area of the passage meana 36b and accordingly reduce the flow of blow-by gasea pas~ing therethrough. As a reYult, the amount of blow-by gnses drawn into the inductlon pa~ageway 24 i~ approximately maintained at a desired or predetermined ratio to the amount of air drawn lnto the combu~tlon chamber 16.
When the lnductlon pa~aageway vacuum is extremely high or low the flow control valve 50 i~ moved into a position to close the pa~age means 36 to reduce the flow of blow-by gases restored into the induction passageway 24 to zero. When the induction pa~sage~ay vacuum i9 extremely low, the engine 14 runs under a high speed and high load condition in which the throttle ., .
- 12 _ .
valve 3~ i~ in its fully open po~ition and accordingly the induction pas~ageway VACUUm approaches the atmo~-pheric pressure. In thi~ instance, the blow-by gases in the crankcase 18 are drawn from the rocker cover 44 i~to the air cleaner 26 through the pas~ag0 means 42 and the oil filter 48 by a vacuum produced in the air cLeaner 26 by a large quantity,of air drawn into the induction pa~ageway Z~ at a high ~peed.
The blow-by gase~ thu~ fed into the induction pa~sageway 24 cau~e variatlon~ in the air-fuel ratio of an air-fuel mixture burned in the combu~tion cham-ber 16 and accordingly the overall air-fuel ratio, since the flow of the blow-by gaJes restored cannot be accurately metered in fact and the air-fuel ratio f the blow-by ga~e~ varie~.
The air-fuel mixture burned in the combustion chamber 16 produce~ engine exhau~t gn~e~ which are di~charged into the exhau~t ga~ pas~ageway 32. The oxygen sensor 64 sense~ the concentration of oxygen in the engine exhauYt gase~ which concentration repre~ents the variation~ in the mixture air-fuel ratio or the o~erall air-fuel ratio to generate an output *ignal repre~enting the ~ensed concentration of oxygen. When the total air-fuel ratio iA lower than the desired air-fuel ratio~ the control circuit ~044543 66 compare~ the magnitude of the output sigrlal of the oxygen sensor 64 with the reference value and generates an output signal fGr causing the mixture forming device Z8 to form an air-fuel mixture diluted to the extent th~t the total air-fuel ratlo is increased to the de~ired air-fuel ratio. The actUAtor 68 i8 energized hy the output Hlgnal of the con~rol circuit 66 to open the valve mean~ of the mixture forming device 28 a period of time corresponding to the output signal to reduce the amount of fuel fed by the mixture forming device 28 to increase the total air-fuel ratio to the deqired air-fuel ratio. On the contrary, when the total air-fuel ratio is higher than the desired air-; fuel ratio, the control circuit 66 generate4 an output 15 signal for cauqing the mixture forming device 28 to f'orm an air-fuel mixture enriched to the extent that the total air-fuel ratio ls reduced to the desired air-fuel ratio. The output signal of the control circuit 66 causes the actuator 68 to open the valve ZO means of the mixture forming device 28 a period of time to increase the amount of fuel fed by the mixture forming device 28 to reduce the total air-fuel ratio 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 blow-by gases ~Q~5~;~
restored into the combuYtion chamber 16 BO that the ex}-aust ga~ purifying device 34 display~ its function best to minimize the content~ of sir pollutants in engine exhaust gases and the operational performance of the engine iJ ~tabillzed.
Although with a conventional crankcase blow-by ga~ re~toring ~yJtem whlch 1~ not comblned wlth an air-fuel ratio control ~ystem, it ha~ been nece~sary to make great efforts in adjusting a flow control In valve to meter the flow of re~tored blow-by ga~e~ to a deYired value and in adju~ting a carburetor or fuel injector to make changeJ in the overall air-fuel ratio by restored blow-by gase~ a~ little a~ posYible, with a crankca~e blow-by gas re~toring sy~tem combined with an air-fuel ratio control system as according to the invention it i~ unnece~sary to make such effortY and a blow-by ga~ flow control valve can be merely replaced by an ori~ice.
It will be appreciated that the invention provides n combination of a crankca~e blow-by gas restoring ~-system and an air-fuel ratio control system which com-bination corrects the overall air-fuel ratio varied by blow-by gase~ restored into a combustion chamber of an engine to a desired air-fuel ratio 80 that an exhaust gas treating device of the engine exhibit its function .
: .: , .
1~4~5~3 be~t, the driveability of the engine i9 ~tabilized, and flow control mean~ of the crankca~e blow-by gas re~toring sy~tem i~ con~iderably simplfied or i9 diApenAed with.
Although the invention hns been described as being applled to an engine includlng a catalytlc converter havlng a ternal cata~yst, the inventiGn can be applied to an englne including other exhaust gas purifying device such n~ A reactor or a catalytic converter having a reduction or oxidation catalyst.
In this in~tance, a de~ired value of the overall air-fuel ratio i~ a value nt which the exhaust gas purifying devlce exhibit~ it~ function best.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A combination of a crankcase blow-by gas restoring system and an air-fuel ratio control system for all internal combustion engine, said crankcase blow-by gas restoring system restoring blow-by gases in a crankcase of an internal combustion engine into a combustion chamber of said engine and comprising passage means for providing fluid communication between said crankcase and an induction passageway of said engine, said air-fuel ratio control system correcting to a desired air-fuel ratio the total air-fuel ratio of all air and fuel fed for formation of engine exhaust gases in an exhaust gas passageway, of said engine, at a certain position which ratio is varied by said blow-by gases restored into said com-bustion chamber, said air-fuel ratio control system comprising a mixture forming device for feeding fuel into air fed by said induction passageway to provide an air-fuel mixture burned in said combustion chamber, sensing means for sensing said total air-fuel ratio, and control means comparing the sensed total air-fuel ratio with said desired air-fuel ratio and controlling said mixture forming device in accordance with a difference between said sensed total air-fuel ratio and said desired air-fuel ratio to correct said total air-fuel ratio to 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 said engine exhaust gases to sense said total 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 into said air, and said control means comprises comparator means generating an error signal representing a difference between said sensed total air-fuel ratio and said desired air-fuel ratio, said comparator means controlling said valve means in accordance with said error signal to adjust the amount of fuel fed into said air to correct said total air-fuel ratio to said desired air-fuel ratio.
4. A combination as claimed in Claim 1, in which said crankcase blow-by gas restoring system further comprises a flow control valve including a valve chamber into which said passage means opens and in which said control valve is located to move in response to the vacuum in said induction passageway at a position downstream of a throttle valve and to divide said valve chamber into upstream and downstream portions, said valve chamber providing between its internal wall and said control valve an annular clearance which provides communication between said upstream and downstream portions, said control valve having a projection extending into and tapering to said passage means to reduce and increase the cross sectional area thereof when said control valve moves in response to increase and decrease in said induction passageway vacuum, respectively.
5. A combination as claimed in Claim 4, in which said crankcase blow-by gas restoring system further comprises passage means for providing fluid communi-cation between an upper portion of said crankcase and an air cleaner of said engine.
6. An internal combustion engine comprising a combustion chamber, a crankcase having therein said combustion chamber and into which blow-by gases escape therefrom, an induction passageway communicating with the ambient atmosphere and opening into said combustion chamber to feed air thereto, a mixture forming device for feeding fuel into air fed by said induction passageway to provide an air-fuel mixture burned in said combustion chamber, an exhaust gas passageway extending from said combustion chamber and conducting engine exhaust gases discharged therefrom, a crankcase blow-by gas restoring system for restoring blow-by gases in said crankcase into said combustion chamber and comprising passage means providing fluid communi-cation between said crankcase and said induction passageway, and an air-fuel ratio control system for correcting to a desired air-fuel ratio the total 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 which ratio is varied by said blow-by gases restored into said combustion chamber, said air-fuel ratio control system comprising sensing means for sensing said total air-fuel ratio, and control means comparing said total air-fuel ratio with said desired air-fuel ratio and controlling said mixture forming device in accordance with a difference between said sensed total air-fuel ratio and said desired air-fuel ratio to correct said total air-fuel ratio 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 total air-fuel ratio.
8. An internal combustion engine as claimed in Claim 6, in which said mixture forming device comprises valve means for controlling the amount of fuel fed into said air, and said control means comprises comparator means generating an error signal representing a difference between said sensed total air-fuel ratio and said desired air-fuel ratio, said comparator means controlling open time of said valve means in accord-ance with said error signal to adjust the amount of fuel fed into said air to correct said total air-fuel ratio to said desired air-fuel ratio.
9. An internal combustion engine as claimed in Claim 6, in which said crankcase blow-by gas restoring system further comprises a flow control valve including a valve chamber into which said passage means opens and in which said control valve is located to move in response to the vacuum in said induction passageway at a position downstream of a throttle valve and to divide said valve chamber into upstream and downstream portions, said valve chamber providing between its internal wall and said control valve an annular clearance which provides communication between said upstream and downstream portions, said control valve having a projection extending into and tapering to said passage means to reduce and increase the cross sectional area thereof when said control valve moves in response to increase and decrease in said induction passageway vacuum, respectively.
10. An internal combustion engine as claimed in Claim 9, in which said crankcase blow-by gas restoring system further comprises passage means providing fluid communication between an upper portion of said crank-case and an air cleaner of said engine.
11. 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 therein a ternary catalyst which concurrently catalytically promotes both oxidation of hydrocarbons (HC) and carbon monoxide (CO) present in said engine exhaust gases and reduction of nitrogen oxides (NOx) present in said engine exhaust gases, said desired air-fuel ratio being a stoichiometric air fuel ratio.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3577875A JPS51110131A (en) | 1975-03-25 | 1975-03-25 | NAINENKIKAN |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1044543A true CA1044543A (en) | 1978-12-19 |
Family
ID=12451345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA248,749A Expired CA1044543A (en) | 1975-03-25 | 1976-03-24 | Combination of a crankcase ventilation system and an air-fuel ratio control system for an engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS51110131A (en) |
| CA (1) | CA1044543A (en) |
| DE (1) | DE2612781A1 (en) |
| GB (1) | GB1530034A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GR80859B (en) * | 1983-12-03 | 1985-04-02 | Pommer Fredi | Improved fuel saving apparatus |
| GB2576912A (en) * | 2018-09-06 | 2020-03-11 | Rcv Engines Ltd | A rotary valve internal combustion engine |
-
1975
- 1975-03-25 JP JP3577875A patent/JPS51110131A/en active Pending
-
1976
- 1976-03-24 CA CA248,749A patent/CA1044543A/en not_active Expired
- 1976-03-25 DE DE19762612781 patent/DE2612781A1/en not_active Withdrawn
- 1976-03-25 GB GB1208076A patent/GB1530034A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1530034A (en) | 1978-10-25 |
| JPS51110131A (en) | 1976-09-29 |
| DE2612781A1 (en) | 1976-10-07 |
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