CA1052646A - Fuel control system for an internal combustion engine - Google Patents
Fuel control system for an internal combustion engineInfo
- Publication number
- CA1052646A CA1052646A CA254,526A CA254526A CA1052646A CA 1052646 A CA1052646 A CA 1052646A CA 254526 A CA254526 A CA 254526A CA 1052646 A CA1052646 A CA 1052646A
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- air
- combustion chamber
- fuel ratio
- sub
- 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
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M7/00—Carburettors with means for influencing, e.g. enriching or keeping constant, fuel/air ratio of charge under varying conditions
- F02M7/23—Fuel aerating devices
- F02M7/24—Controlling flow of aerating air
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B19/00—Engines characterised by precombustion chambers
- F02B19/10—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder
- F02B19/1019—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber
- F02B19/1023—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber pre-combustion chamber and cylinder being fed with fuel-air mixture(s)
- F02B19/1028—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber pre-combustion chamber and cylinder being fed with fuel-air mixture(s) pre-combustion chamber and cylinder having both intake ports or valves, e.g. HONDS CVCC
- F02B19/1052—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber pre-combustion chamber and cylinder being fed with fuel-air mixture(s) pre-combustion chamber and cylinder having both intake ports or valves, e.g. HONDS CVCC controlling, e.g. varying fuel-air ratio, quantity of charge
-
- 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
- F02D35/0053—Controlling fuel supply by means of a carburettor
- F02D35/0061—Controlling the emulsifying air only
-
- 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
- F02M13/00—Arrangements of two or more separate carburettors; Carburettors using more than one fuel
- F02M13/02—Separate carburettors
- F02M13/04—Separate carburettors structurally united
- F02M13/046—Separate carburettors structurally united arranged in parallel, e.g. initial and main carburettor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Abstract
Abstract of the Disclosure:
A fuel control system for an internal combustion engine of torch ignition type including a main combustion chamber and sub-combustion chamber, wherein an air/fuel mixture fed to said sub-combustion chamber is ignited by a spark plug to produce a torch which spreads into the main combustion chamber. The fuel control system comprises air/fuel ratio sensing means operative to produce a signal in response to the detected air/fuel ratio of the overall intake mixture and fuel flow rate correction means operative to correct the flow of fuel delivered from a fuel supply system responsive to the output signal of said air/fuel sensing means, whereby feedback control is provided to regulate the air/fuel ratio of the overall intake mixture toward a predetermined value.
A fuel control system for an internal combustion engine of torch ignition type including a main combustion chamber and sub-combustion chamber, wherein an air/fuel mixture fed to said sub-combustion chamber is ignited by a spark plug to produce a torch which spreads into the main combustion chamber. The fuel control system comprises air/fuel ratio sensing means operative to produce a signal in response to the detected air/fuel ratio of the overall intake mixture and fuel flow rate correction means operative to correct the flow of fuel delivered from a fuel supply system responsive to the output signal of said air/fuel sensing means, whereby feedback control is provided to regulate the air/fuel ratio of the overall intake mixture toward a predetermined value.
Description
~05i~4~
The present invention relates to a fuel control system for an internal combustion engine and, more particularly to a fuel control system for a torch ignition type internal combustion engine.
As is widely known, torch ignition type internal combus-tion engines are equipped with a main comb~stion chamber supplied , with a lean fuel mixture and a sub-combustion chamber supplied with an enriched mixture. Ignition of the enriched mixture in the sub-combustion chamber by means of a spark plug produces a ;10 torch which is caused to spread into the main combustion chamber and combust the lean miture supplied thereto. Such torch ignition type internal engines as a whole, therefore, are ,~
capableofoperating stably owing to the lean mixture and thus ~fford greatly improved fuel economy and a reduction in the ,,15 quantity of NOX products due to the fact that the maximum combustion temperature is lower than is the case with the customary spark ignition engine.' It is, therefore, an object of the present invention to provide an improved fuel control system for an internal combustion engine of a motor vehicle.
. It is another object of the present invention to ' provide an improved fuel control system adapted to control ,`~, the amount of fuel being supplied to an induction passage of a carburetor of an internal combustion engine for,levelling . ~ . .
the air/fuel ratio of an air/fuel mixture at a predetermined : ... ' :
~. . . .
'" ' .' ' ' ~ .
. r .
105;~;46 ~alue.
It is still another object of the present invention to provide an improved fuel control system specifically suited or use in a torch ignition type internal combustion engine of a motor vehicle.
It is a further object of the present invention to provide an improved fuel control system for a torch ignition type internal combustion engine of a motor vehicle, which fuel~ control system provides feed back control in the torch ignition type internal combustion engine so as to regulate the air/fuel ratio of an entire air/fuel mixture toward a predetermined air/fuel ratio.
It is a still further object of the present invention to-provide an improved fuel control system in a torch ignition type internal combustion engine by which it is possible to enhance fuel economy and engine stability while levelling the concentration of HC, Co and NOX products so as to exploit more fully the capabilities of purification mechanisms ~nstalled in an exhaust system, thereby ramarkably enhancing overall exhaust purification.
~ These and other objects, features and advantages of s the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a graph which shows the relationshi~
'' ` ' .
:, .
.
1()5;~4~i between the air/fuel ratio of the intake mixture and the quantity of NOX product Fig. 2 is a schematic view showing a preferred embodiment of a fuel control system according to the present invention;
Fig. 3 is a view of a portion of a main carburetor ;
ghown in Fig. 2; and Fig. 4 is a view of a portion of a sub-carburetor shown in Fig. 2.
By way of example, Fig. 1 illustrates a spark ~gnition engine for a case in which gasoline is used as a ~uel. In this engine, when the intake air/fuel mixture ratio attains a value substantially equivalent to the stoichiometric a~r/fuel ratio, the quantity of NOX produced in extremely high as shown by solid line a, whereas a torch ignition ~ngine in the neighborhood of the stoichiometric air/fuel ratio reduces the NOX product to approximately 1/2 to 1/3 the quantity of the spark ignition engine as shown by broken line b. Thus, when attempting to suppress the NOX
product to equal levels for both the standard spark ignition engine and torch ignition engine, the intake mixture must either be enriched or rarified in the extreme, a factor which diminishes fuel economy and engine stability. The torch ignition engine, moreover, greatly reduces the quantity of CO and ~C products due to the fact that the torch from the ."~, , .
.- . - , ... .
~
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1os~646 sub-combustion chamber causes combustion of the lean mixture in the main combustion chamber, resulting in a slower burn than is the case with the spark ignition engine.
.~ In such a torch ignition engine featuring an essential-S ly purified exhaust, if the overall air/fuel ratio of the intake mixture is maintained at an ordinarily predetermined value, it i8 possible to further enhance fuel economy and engine stability while leveling- the concentration of HC, C0 and N0x products 80 as to ex.ploit more fully the capabilities of the purifica-- 10 tion mechanisms installed in the exhaust system, thereby remarkably enhancing overall exhaust purification.
: In light of these factors, the present invention proposes to provide feedback control in a torch ignition engine so as to regulate the air/fuel ratio of the entire intake mixture toward a predetermined air/fuel ratio.
A preferred embodiment of the present invention will ~! . now be described~with respect to the accompanying drawings.
In Fig. 2 the numeral 10 represents a cylinder block, 12 a main combustion chamber ahd 14 a sub-combustion chamber provided with spark plug 16 and communicated across a port 18 - with said main combustion chamber 12. The numeral 20 represents a fuel supply system such as a main combustion ~ chamber intake manifold (hereinafter referred to as the main . ; manifold) which supplies to the main combustion chamber a lean : . .
. 2~ air/fuel mixture set in advance by a caburetor 22, 24 a .
. . ..
- ` - 5 0 . ' ' ~ ' ' .
, 105'~646 ~ubcombustion chamber intake manifold(hereinafter referred to as the sub-manifold) which feeds to the sub-combustion chamber 14 an enriched air/fuel mixture similarly set in ~dvance, 26 an exhaust manifold ., 28 a triple catalytic converter ( a catalyst functioning jointly to both reduce : NOX and oxidize HC AND CO), and 30 an exhaust line (exhaust pipe) connected to exhaust manifold 26. An enriched .mixture fed from said carburetor to sub-combustion chamber 14 ~ia sub-manifold 24 is ignited and combusted by spark plug 16, thereby generating a torch which spreads from port 18 into :.
main combustion chamber 12. As a consequence, the lean mixture supplied from carburetor 22 to main combustion chamber 12 via main manifold 20 is effectively combusted.
According to such a structure, an air/fuel ratio .
sensing means responsive to the air/fuel ratio and operative to ge~erate a signal is employed. By way of example, installed .
in exhaust line 30 is an exhaust sensor 32 such an as 2' CO, . CO2, HC or NOX sensor responsive to the concentration of .` emission products closely related to the air/fuel ratio of the entire intake mixture. In addition, carburetor 22 is equipped : .with a fuel flo~ rate control system 34 for correcting the flow rate of the fuel supplied from said carburetor 22 by means of an electric control circuit 36 responsive to the detection , . . .
~ signal from said exhaust sensor 32.
:: : 25 In more detail, Flg. 3 shows such an arrangement in , .l 6 . ' ' ' .
~ r : . ~
.
.. -, ~ : ...
105'~646 whish a main combustion chamber carburetor (hereinafter referred to as the main carburetor) is equipped with a fuel control system. Here, main bleed 40 of main caburetor 22 is provided with auxiliary air bleed 42 while fuel'' correction S system 34 comprising an actuator 44 such as a magnetic valve is installed in the line of said auxiliary air bleed 42 in order to control opening and closing of the line or variation in the openlng of said line.
~; Exhaust sensor 32 detects the concentration of combustion gas products resulting from the intake mixture the air/fuel ratio of which is set beforehand' by main carburetor 22A and sub-combustio,n chamber carburetor 22B (hereinafter referred to as the sub-car~uretor) to be described hereinbelow.
Upon such detéction, exhaust sensor 32 produces an output the value of which is compared with a reference voltage in electric control circuit 36, thereby allowing control of fuel flow. ' -; For example, when the air/fuel ratio of the entire intake mixture is detected to be in a lean state owing to a disparity -between the output voltage of exhaust sentor 32 and the reference ' 20 voltage, electric control circuit 36 is operative to transmit a com~and signal to actuator 44 thereby to close auxiliary air bleed 42 and cut off the supply of air. This causes the , flow of fuel from main nozzle 46 to attain a flow rate which has been set by the diameters of main air bleed jet 48 and ' 25 main fuel jet 50. - ' " .
'' ' ' .
_ 7 _ r . . .
~1~5'~646 ~
Con~ersely, when the air/fuel ratio is sensed to be in an enriched state, auxiliary air bleed 42 is opened and the ~upply of air increased thereby to reduce the quantity of fuel which flows from nozzle 46 and provide feedback control 1 5 80 as to regulate the air/fuel ratio of the intake mixture - toward the standard predetermined air/fuel ratio. It should be noted that although Fig. 3 illustrates only the case for the main syste~ the operation is identical for the slow-running - mixture suppiy system.
Turning now to a more detailed description of the fuel correction system for sub-carburetor 22B as shown in Fig. 4, main air bleed 52 and slow air bleed 54 of sub-carburetor --~
~ 22B are provided, respectively, with auxiliary air bleeds 56 ! and 58 the respective lines of which are equipped with fuel , 15 correction systesm 34 comprising actuators 60 and 62. Thus, correction of fuel flow rate is conducted in identical fashion as was the case for said main carburetor 22A, thereby :
making it possible to regulate the air/fuel ratio toward a predetermined value by means of feedback control.
If overall control of the air/fuel ratio is finally .. . . .
adopted by providing said fuel correction system for main - carburetor 22A and sub-carburetor 22B thereby to control the air~fuel ratio in both carburetors, then feedback control can ; be conducted all the more readily and accurately enabling the i 25 stability of a torch ignition engine to be remarkably improved.
, ~ - 8 -. , .
:,` . .
.'' ` ' , .
: . .
, ' ` ' ~.
' ' ' ~.os~6~6 Moreover, in a structure adapted so as to supply an enriched mixture to a sub-combustion chamber, a sub-manifold is branched off from a main manifold so as to feed a fuel which flows downward along the wall surface of the main intake manifold to the sub-manifold and into thesub-combustion chamber.
According to such a structure, a single carburetor is sufficient so that the air/fuel ratio of this single carburetor alone is controlled by feedback.
In Fig. ~, the numeral 64 represents a throttle valve, 10 ` 66 a main air bleed jet for the sub-carburetor, 68 a main fuel ~et, 70 a slow fuel jet, 72 a main nozzle, 74 a slow port, 76 a throttle valve, and 78 a float chamberO If a triple - catalytic converter lla is employed as exhaust purification means as previously mentioned, the catalytic convertor provides optimum purification efficiency when the air/fuel ratio is substantially the same as the stoichiometric air/
fuel ratio; hence, by adopting the stoichiometric air/fuel ratio as the objective value of t~e air/fuel ratio control, exhaust can be further purified.
Alth~ugh the present embodiment has been described for a,case in which an air bleed and actuator are provided as the fuel flow rate correction system, an actuator which controls the variation of a line opening may just as well be installed in another fuel line. It is also permissible to employ a fuel injectlon system rather than said carburetors as . .
i ., ~ . .
_ 9 _ -. ~ ' .
r ~ ' ' ' , .
a fuel supply system. Further, it is also possible to employ as air/fuel ratio detecting means a sensor, other than said exhaust sensor, which is adapted so as to detect the ion current within the engine combustion chamber and produce an output signal in response to the air/fuel ratio.~
Thus, according to the features of this invention, feedback control is applied to the air/fuel ratio of the intake fuel mixture supplied from the main carburetor and/or sub-carburetor of a torch ignition engine characterized by an essentially purified exhaust, ultimately making it possible to provide feedback control of the overall air/fuel ratio which can be regulated toward a predetermined value, thereby to maintain an air/fuel ratio best suited to fuel economy and engine stability, enabling fuel economy and engine stability to be further enhanced. Moreover, in such cases where a triple catalytic converter is installed in the exhaust system, an air/fuel ratio advantageous in view of reducing exhaust emissions can be achieved by constantly maintaining the air/fuel ratio of the overall intake mixture in the vicinity of the stoichiometric air/fuel ratio, whereby the operation efficiency ~purification efficiency)of the triple catalytic converter is kept at a high level so that the quantity of HC, CO and NOX
released to the atmosphere can be remarkably reduced.
Furthermore, by maintaining the air/fuel ratio at a predetermined value suitable for purification devices other than the triple ` 10 - ' -.
-' ' , :~ ' 105'~646 catalytic converter, it is possible to bring into full play the purifying efficiency of reactors or catalytic devices ~uch as oxidizing or reducing catalytic converters.
By additionally making joint use of an exhaust recirculation system which causes a portion of the exhaust to flow back through the intake system,the quantity of NOX
products can be further reduced so as to lessen the burden on the catalytic converter and permit more effective treatment of exhaust. In a case where such an exhaust recirculation lQ system is utilized, NOX products can be effectively suppressed without establishing an especially lean mixture in the main combustion chamber since rarification is substantially .
accomplished by exhaust flowback. In this case a single carburetor suffices while an exhaust recirculation line may, for example, be connected to the main manifold downstream of --the sub-manifold branch so as to feed back-flowing exhaust solely to the main combus~ion chamber.
- While the present invention has been shown and describ-ed with reference to particular embodiments by way of example, it should be noted that various changes or modifications may ~e made without departing from the scope of the present invention.
~;, , , .
, ' ' ' ': ' -.. . .
. .
~: .
The present invention relates to a fuel control system for an internal combustion engine and, more particularly to a fuel control system for a torch ignition type internal combustion engine.
As is widely known, torch ignition type internal combus-tion engines are equipped with a main comb~stion chamber supplied , with a lean fuel mixture and a sub-combustion chamber supplied with an enriched mixture. Ignition of the enriched mixture in the sub-combustion chamber by means of a spark plug produces a ;10 torch which is caused to spread into the main combustion chamber and combust the lean miture supplied thereto. Such torch ignition type internal engines as a whole, therefore, are ,~
capableofoperating stably owing to the lean mixture and thus ~fford greatly improved fuel economy and a reduction in the ,,15 quantity of NOX products due to the fact that the maximum combustion temperature is lower than is the case with the customary spark ignition engine.' It is, therefore, an object of the present invention to provide an improved fuel control system for an internal combustion engine of a motor vehicle.
. It is another object of the present invention to ' provide an improved fuel control system adapted to control ,`~, the amount of fuel being supplied to an induction passage of a carburetor of an internal combustion engine for,levelling . ~ . .
the air/fuel ratio of an air/fuel mixture at a predetermined : ... ' :
~. . . .
'" ' .' ' ' ~ .
. r .
105;~;46 ~alue.
It is still another object of the present invention to provide an improved fuel control system specifically suited or use in a torch ignition type internal combustion engine of a motor vehicle.
It is a further object of the present invention to provide an improved fuel control system for a torch ignition type internal combustion engine of a motor vehicle, which fuel~ control system provides feed back control in the torch ignition type internal combustion engine so as to regulate the air/fuel ratio of an entire air/fuel mixture toward a predetermined air/fuel ratio.
It is a still further object of the present invention to-provide an improved fuel control system in a torch ignition type internal combustion engine by which it is possible to enhance fuel economy and engine stability while levelling the concentration of HC, Co and NOX products so as to exploit more fully the capabilities of purification mechanisms ~nstalled in an exhaust system, thereby ramarkably enhancing overall exhaust purification.
~ These and other objects, features and advantages of s the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a graph which shows the relationshi~
'' ` ' .
:, .
.
1()5;~4~i between the air/fuel ratio of the intake mixture and the quantity of NOX product Fig. 2 is a schematic view showing a preferred embodiment of a fuel control system according to the present invention;
Fig. 3 is a view of a portion of a main carburetor ;
ghown in Fig. 2; and Fig. 4 is a view of a portion of a sub-carburetor shown in Fig. 2.
By way of example, Fig. 1 illustrates a spark ~gnition engine for a case in which gasoline is used as a ~uel. In this engine, when the intake air/fuel mixture ratio attains a value substantially equivalent to the stoichiometric a~r/fuel ratio, the quantity of NOX produced in extremely high as shown by solid line a, whereas a torch ignition ~ngine in the neighborhood of the stoichiometric air/fuel ratio reduces the NOX product to approximately 1/2 to 1/3 the quantity of the spark ignition engine as shown by broken line b. Thus, when attempting to suppress the NOX
product to equal levels for both the standard spark ignition engine and torch ignition engine, the intake mixture must either be enriched or rarified in the extreme, a factor which diminishes fuel economy and engine stability. The torch ignition engine, moreover, greatly reduces the quantity of CO and ~C products due to the fact that the torch from the ."~, , .
.- . - , ... .
~
, r . , ' ~
1os~646 sub-combustion chamber causes combustion of the lean mixture in the main combustion chamber, resulting in a slower burn than is the case with the spark ignition engine.
.~ In such a torch ignition engine featuring an essential-S ly purified exhaust, if the overall air/fuel ratio of the intake mixture is maintained at an ordinarily predetermined value, it i8 possible to further enhance fuel economy and engine stability while leveling- the concentration of HC, C0 and N0x products 80 as to ex.ploit more fully the capabilities of the purifica-- 10 tion mechanisms installed in the exhaust system, thereby remarkably enhancing overall exhaust purification.
: In light of these factors, the present invention proposes to provide feedback control in a torch ignition engine so as to regulate the air/fuel ratio of the entire intake mixture toward a predetermined air/fuel ratio.
A preferred embodiment of the present invention will ~! . now be described~with respect to the accompanying drawings.
In Fig. 2 the numeral 10 represents a cylinder block, 12 a main combustion chamber ahd 14 a sub-combustion chamber provided with spark plug 16 and communicated across a port 18 - with said main combustion chamber 12. The numeral 20 represents a fuel supply system such as a main combustion ~ chamber intake manifold (hereinafter referred to as the main . ; manifold) which supplies to the main combustion chamber a lean : . .
. 2~ air/fuel mixture set in advance by a caburetor 22, 24 a .
. . ..
- ` - 5 0 . ' ' ~ ' ' .
, 105'~646 ~ubcombustion chamber intake manifold(hereinafter referred to as the sub-manifold) which feeds to the sub-combustion chamber 14 an enriched air/fuel mixture similarly set in ~dvance, 26 an exhaust manifold ., 28 a triple catalytic converter ( a catalyst functioning jointly to both reduce : NOX and oxidize HC AND CO), and 30 an exhaust line (exhaust pipe) connected to exhaust manifold 26. An enriched .mixture fed from said carburetor to sub-combustion chamber 14 ~ia sub-manifold 24 is ignited and combusted by spark plug 16, thereby generating a torch which spreads from port 18 into :.
main combustion chamber 12. As a consequence, the lean mixture supplied from carburetor 22 to main combustion chamber 12 via main manifold 20 is effectively combusted.
According to such a structure, an air/fuel ratio .
sensing means responsive to the air/fuel ratio and operative to ge~erate a signal is employed. By way of example, installed .
in exhaust line 30 is an exhaust sensor 32 such an as 2' CO, . CO2, HC or NOX sensor responsive to the concentration of .` emission products closely related to the air/fuel ratio of the entire intake mixture. In addition, carburetor 22 is equipped : .with a fuel flo~ rate control system 34 for correcting the flow rate of the fuel supplied from said carburetor 22 by means of an electric control circuit 36 responsive to the detection , . . .
~ signal from said exhaust sensor 32.
:: : 25 In more detail, Flg. 3 shows such an arrangement in , .l 6 . ' ' ' .
~ r : . ~
.
.. -, ~ : ...
105'~646 whish a main combustion chamber carburetor (hereinafter referred to as the main carburetor) is equipped with a fuel control system. Here, main bleed 40 of main caburetor 22 is provided with auxiliary air bleed 42 while fuel'' correction S system 34 comprising an actuator 44 such as a magnetic valve is installed in the line of said auxiliary air bleed 42 in order to control opening and closing of the line or variation in the openlng of said line.
~; Exhaust sensor 32 detects the concentration of combustion gas products resulting from the intake mixture the air/fuel ratio of which is set beforehand' by main carburetor 22A and sub-combustio,n chamber carburetor 22B (hereinafter referred to as the sub-car~uretor) to be described hereinbelow.
Upon such detéction, exhaust sensor 32 produces an output the value of which is compared with a reference voltage in electric control circuit 36, thereby allowing control of fuel flow. ' -; For example, when the air/fuel ratio of the entire intake mixture is detected to be in a lean state owing to a disparity -between the output voltage of exhaust sentor 32 and the reference ' 20 voltage, electric control circuit 36 is operative to transmit a com~and signal to actuator 44 thereby to close auxiliary air bleed 42 and cut off the supply of air. This causes the , flow of fuel from main nozzle 46 to attain a flow rate which has been set by the diameters of main air bleed jet 48 and ' 25 main fuel jet 50. - ' " .
'' ' ' .
_ 7 _ r . . .
~1~5'~646 ~
Con~ersely, when the air/fuel ratio is sensed to be in an enriched state, auxiliary air bleed 42 is opened and the ~upply of air increased thereby to reduce the quantity of fuel which flows from nozzle 46 and provide feedback control 1 5 80 as to regulate the air/fuel ratio of the intake mixture - toward the standard predetermined air/fuel ratio. It should be noted that although Fig. 3 illustrates only the case for the main syste~ the operation is identical for the slow-running - mixture suppiy system.
Turning now to a more detailed description of the fuel correction system for sub-carburetor 22B as shown in Fig. 4, main air bleed 52 and slow air bleed 54 of sub-carburetor --~
~ 22B are provided, respectively, with auxiliary air bleeds 56 ! and 58 the respective lines of which are equipped with fuel , 15 correction systesm 34 comprising actuators 60 and 62. Thus, correction of fuel flow rate is conducted in identical fashion as was the case for said main carburetor 22A, thereby :
making it possible to regulate the air/fuel ratio toward a predetermined value by means of feedback control.
If overall control of the air/fuel ratio is finally .. . . .
adopted by providing said fuel correction system for main - carburetor 22A and sub-carburetor 22B thereby to control the air~fuel ratio in both carburetors, then feedback control can ; be conducted all the more readily and accurately enabling the i 25 stability of a torch ignition engine to be remarkably improved.
, ~ - 8 -. , .
:,` . .
.'' ` ' , .
: . .
, ' ` ' ~.
' ' ' ~.os~6~6 Moreover, in a structure adapted so as to supply an enriched mixture to a sub-combustion chamber, a sub-manifold is branched off from a main manifold so as to feed a fuel which flows downward along the wall surface of the main intake manifold to the sub-manifold and into thesub-combustion chamber.
According to such a structure, a single carburetor is sufficient so that the air/fuel ratio of this single carburetor alone is controlled by feedback.
In Fig. ~, the numeral 64 represents a throttle valve, 10 ` 66 a main air bleed jet for the sub-carburetor, 68 a main fuel ~et, 70 a slow fuel jet, 72 a main nozzle, 74 a slow port, 76 a throttle valve, and 78 a float chamberO If a triple - catalytic converter lla is employed as exhaust purification means as previously mentioned, the catalytic convertor provides optimum purification efficiency when the air/fuel ratio is substantially the same as the stoichiometric air/
fuel ratio; hence, by adopting the stoichiometric air/fuel ratio as the objective value of t~e air/fuel ratio control, exhaust can be further purified.
Alth~ugh the present embodiment has been described for a,case in which an air bleed and actuator are provided as the fuel flow rate correction system, an actuator which controls the variation of a line opening may just as well be installed in another fuel line. It is also permissible to employ a fuel injectlon system rather than said carburetors as . .
i ., ~ . .
_ 9 _ -. ~ ' .
r ~ ' ' ' , .
a fuel supply system. Further, it is also possible to employ as air/fuel ratio detecting means a sensor, other than said exhaust sensor, which is adapted so as to detect the ion current within the engine combustion chamber and produce an output signal in response to the air/fuel ratio.~
Thus, according to the features of this invention, feedback control is applied to the air/fuel ratio of the intake fuel mixture supplied from the main carburetor and/or sub-carburetor of a torch ignition engine characterized by an essentially purified exhaust, ultimately making it possible to provide feedback control of the overall air/fuel ratio which can be regulated toward a predetermined value, thereby to maintain an air/fuel ratio best suited to fuel economy and engine stability, enabling fuel economy and engine stability to be further enhanced. Moreover, in such cases where a triple catalytic converter is installed in the exhaust system, an air/fuel ratio advantageous in view of reducing exhaust emissions can be achieved by constantly maintaining the air/fuel ratio of the overall intake mixture in the vicinity of the stoichiometric air/fuel ratio, whereby the operation efficiency ~purification efficiency)of the triple catalytic converter is kept at a high level so that the quantity of HC, CO and NOX
released to the atmosphere can be remarkably reduced.
Furthermore, by maintaining the air/fuel ratio at a predetermined value suitable for purification devices other than the triple ` 10 - ' -.
-' ' , :~ ' 105'~646 catalytic converter, it is possible to bring into full play the purifying efficiency of reactors or catalytic devices ~uch as oxidizing or reducing catalytic converters.
By additionally making joint use of an exhaust recirculation system which causes a portion of the exhaust to flow back through the intake system,the quantity of NOX
products can be further reduced so as to lessen the burden on the catalytic converter and permit more effective treatment of exhaust. In a case where such an exhaust recirculation lQ system is utilized, NOX products can be effectively suppressed without establishing an especially lean mixture in the main combustion chamber since rarification is substantially .
accomplished by exhaust flowback. In this case a single carburetor suffices while an exhaust recirculation line may, for example, be connected to the main manifold downstream of --the sub-manifold branch so as to feed back-flowing exhaust solely to the main combus~ion chamber.
- While the present invention has been shown and describ-ed with reference to particular embodiments by way of example, it should be noted that various changes or modifications may ~e made without departing from the scope of the present invention.
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Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an internal combustion engine of torch ig-nition type including a main combustion chamber and sub-combustion chamber, wherein an air/fuel mixture fed to said sub-combustion chamber is ignited by a spark plug to produce a torch which spreads into the main com-bustion chamber, a fuel control system comprising air/fuel ratio sensing means operative to produce a signal in response to the detected air/fuel ratio of the overall intake mixture and fuel flow rate correction means operative to correct the flow of fuel delivered from a fuel supply system responsive to the output signal of said air/fuel sensing means, whereby feedback control is provided to regulate the air/fuel ratio of the overall intake mixture toward a predetermined value.
2. A fuel control system for an internal combustion engine according to claim 1, in which said fuel flow rate correction means is located in the fuel supply system of the main combustion chamber, whereby feedback control is provided to regulate the air/fuel ratio of the overall intake mixture toward a predetermined value.
3. A fuel control system for an internal combustion engine according to claim 1, in which said fuel flow rate correction means is located in the fuel supply system of the sub-combustion chamber, whereby feedback control is provided to regulate the air/fuel ratio of the overall intake mixture toward a predetermined value.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP50071268A JPS51146634A (en) | 1975-06-11 | 1975-06-11 | Fuel control system of internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1052646A true CA1052646A (en) | 1979-04-17 |
Family
ID=13455794
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA254,526A Expired CA1052646A (en) | 1975-06-11 | 1976-06-10 | Fuel control system for an internal combustion engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS51146634A (en) |
| CA (1) | CA1052646A (en) |
| DE (1) | DE2626059A1 (en) |
| GB (1) | GB1528543A (en) |
-
1975
- 1975-06-11 JP JP50071268A patent/JPS51146634A/en active Pending
-
1976
- 1976-06-10 DE DE19762626059 patent/DE2626059A1/en not_active Withdrawn
- 1976-06-10 CA CA254,526A patent/CA1052646A/en not_active Expired
- 1976-06-11 GB GB24270/76A patent/GB1528543A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS51146634A (en) | 1976-12-16 |
| DE2626059A1 (en) | 1976-12-16 |
| GB1528543A (en) | 1978-10-11 |
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