CA1102192A - Carburetor - Google Patents
CarburetorInfo
- Publication number
- CA1102192A CA1102192A CA317,616A CA317616A CA1102192A CA 1102192 A CA1102192 A CA 1102192A CA 317616 A CA317616 A CA 317616A CA 1102192 A CA1102192 A CA 1102192A
- Authority
- CA
- Canada
- Prior art keywords
- fuel flow
- duty cycle
- passage
- fuel
- metering
- 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
- F02D35/0053—Controlling fuel supply by means of a carburettor
- F02D35/0069—Controlling the fuel flow 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
- F02M3/00—Idling devices for carburettors
- F02M3/08—Other details of idling devices
- F02M3/09—Valves responsive to engine conditions, e.g. manifold vacuum
-
- 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
- F02M7/12—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves
- F02M7/18—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves with means for controlling cross-sectional area of fuel-metering orifice
- F02M7/20—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves with means for controlling cross-sectional area of fuel-metering orifice operated automatically, e.g. dependent on altitude
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of The Air-Fuel Ratio Of Carburetors (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
CARBURETOR
Abstract of the Disclosure A carburetor main fuel passage receives fuel both through a primary metering orifice and through a supplementary metering orifice controlled by a pulse width modulated duty cycle operated metering valve.
A rich adjusting needle limits fuel flow through the supplementary metering orifice and is set to establish the high fuel flow desired through the passage at one particular value of the duty cycle, and a lean adjusting needle limits fuel flow through the primary metering orifice and is set to establish the low fuel flow desired through the passage at another particular value of the duty cycle; with this carburetor, a desired fuel flow band width is achieved over a selected range of duty cycles.
Abstract of the Disclosure A carburetor main fuel passage receives fuel both through a primary metering orifice and through a supplementary metering orifice controlled by a pulse width modulated duty cycle operated metering valve.
A rich adjusting needle limits fuel flow through the supplementary metering orifice and is set to establish the high fuel flow desired through the passage at one particular value of the duty cycle, and a lean adjusting needle limits fuel flow through the primary metering orifice and is set to establish the low fuel flow desired through the passage at another particular value of the duty cycle; with this carburetor, a desired fuel flow band width is achieved over a selected range of duty cycles.
Description
z CARBURETOR
This invention relates to a carburetor particularly suitable for operation in a closed loop fuel system.
Several carburetors have been proposed for . .
the purpose of creating an air~fuel mixture of sub-; stantially constant (usually stoichiometric) air-fuel ratio for an internal combustion engine. In general, it has been contemplated that such a carburetor would be used in a closed loop system having a sensor which, for example, measures the oxygen content of the engine exhaust gases as an indication of the air-fuel ratio of the mixture created for the engine and which initiates a feedback signal causing the carburetor to create a mixture of the desired air-fuel ratio.
Certain carburetors proposed for that application have an electronically controlled device which drives fuel metering apparatus between rich and lean positions according to a pulse width modulated duty cycle to maintain the metering apparatus in the ` ~ lean position for a portion of the duty cycle ana in - the rich position for the remainder of the duty cycle.
The carburetor thus duty cycle modulates the fuel flow between a maximum and a minimum and then averages the 25 maximum and minimum fuel flows to create a mixture of the desired air-fuel ratio.
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:
one such carburetor, in particular, has a main fuel passage containing a primary metering orifice and a supplementary metering orifice. The metering apparatus has a valve controlling the supplementary metering orifice and is driven, between a rich position permitting fuel flow through the supplementary orifice and a lean position obstructing fuel flow through the supplementary orifice, by a solenoid coil energized according to a pulse width modulated duty cycle. Under control of a feedback signal, the solenoia coil is energized according to the duty cycle which results in a mixture of the desired air-fuel ratio. Among the advantages some perceive for such a system is the ability to loosen tolerances on the metering area of the primary and supplementary orifices, for in such a system fuel flow is controlled by the feedbac~ signal and errors in fuel flow are corrected by the feedback ; signal.
This invention provides a carburetor of that ; 20 type having structure which improves its suitability for duty cycle modulation of the fuel flow and thus enhances its suitability for operation in a closed loop fuel system.
This invention is founded upon the discovery that, in such a carburetor, the change in fuel flow which results from a change in the duty cycle should be carefully established; that is, we believe a desired ~`~
~Z~92 ' high fuel flow should occur at a duty cycle of one partlcular value and a desired low fuel flow should occur at a duty cycle of another particular value so that a deslred fuel flow band width is achieved over the selected range of duty cycles between those parkicular valuesO
~ Accordingly, this invention provides a ;j~ carbu~etor in which the main fusl passage contains a primary metering orifice and a supplementary metering orifice and in which a valve controlling the ~ supplementary metering orifice forms part of metering ; apparatus that is driven, between a rich position permitting fuel flow through the supplementary orifice and a lean position obstructing fuel flow through the supplementary orifice, by a solenoid coil energized according to a duty cycle. The carburetor provided by this invention further includes a rich adjusting needle which limits fuel flow through the supplementary orifice to establish the high fuel flow desired at one particular value of the duty cycle and further includes a lean adjusting needle which limits fuel flow through the primary orifice to establish the low fuel flow desired at another particular value of the duty cycle.
Thus with the carburetor provided by this invention, a desired fuel flow band width may be achieved over a selected range of duty cycles.
' ~Z~2 The details as well as other features and advantages of this invention are set forth in the following description of a preferred embodiment and . are shown in the drawing in which the sole figure is ~ 5 a schematic view of the main and idle metering systems - o a carburetor employing this invention.
~: Referring to the drawing, an internal combustion engine carburetor 10 has an air induction passage 12 controlled by a choke 14 and a throttle 16.
; 10 A fuel bowl 18 delivers fuel through a primary main metering orifice 20 and a supplementary main metering orifice 22 into a main fuel passàge 24 which discharges through a nozzle 26 into a venturi cluster 28 disposed in induction passage 12.
An idle fuel passage 30 has a pick-up tube 32 extending iiltO main uel passage 24, an idle discharge port 34 opening into induction passag~. 12 past a mixture adjusting needle 36, and an off-idle port 38 opening into induction passage 12 adjacent throttle 16.
The usual side idle air bleed 40 and lower idle air bleed 42 open into idle fuel passage 30 on -~ opposite sides of a~ idle channel restrlction 44, and an air bleed passage 46 extends to the upper portion 25 48 of idle fuel passage 30. Air bleed passage 46 ~,.
J ~2~l~32 includes an inlet portion 50 having sections 52 and 54 . extending through a housing 56 to an annular region 58 . and a discharge portion 60 which includes a section 62 opening through a boss 64 surrounded by annular region 58 and sections 66 and 68 which lead through housing 56 to a - section 70 opening into idle fuel passage 30.
~ Housing 56 has a bore 72 supporting the steel .~ casing 74 of a solenoid coil assembly 76. The upper end of casing 74 has tabs 78 bent over a steel end plate 80.
A domed stainless steel spring washer 82 reacts against end plate 80 and pushes a spool 84 downwardly against .. ; a shoulder 86 of casing 74, a flange 88 of a steel end member 90 being sandwiched therebetween.
Spool 84 includes an extension 92 which reaches upwardly to guide a nickel plated steel armature 94.
A rubber seal member 96 surrounds extension 92.
The upper end of armature 94 carries a VITON* tip 98 forming a bleed valve which seats across boss 64 to control air flow through bleed passage 46, . ~20 from annular region 58 to section 62. The lower end .of armature 94 receives a stainless steel push rod 100 having a stainless steel metering valve 102 at its lower end. A stainless steel spring 104 is secured -in a groove about metering valve 102 and seats against a shoulder 106 at the lower end of casing 74 to bias * trade mark , . . .
1~2~9~
metering valve 102 away from supplemèntary metering orifice 22 and, acting through push rod 100, to engage bleed valve 98 across boss 64.
When a coil 108 wound on spool 84 is ener-gized, armature 94 is drawn downwardly against the bias of spring 104 to disengage bleed valve 98 from : boss 64 and to engage metering valve 102 in supple-mentary metering orifice 22.
; An adapter 110 is pressed on the lower tip 10 112 of casing 74 and pQsitions a sealing ring 114 in : the enla~ged bore 116 of a boss 118 disposed in the floor of fuel bowl 18. Sealing ring 114 compensates for minor misalignment between boss 118 and housing 56.
In operation, the metering apparatus 15 (metering valve 102, armature 94 and bleed valva 98~
: is biased upwardly by spring 104 to the rich position shown in the drawing, determined by engagement of bleed valve 98 with boss 64. In the rich position, metering valve 102 permits fuel flow through supple-; 20 mentary metering orifice 22 while bleed valve 98 obstructs air flow through bleed passage 46 and thus : permits increased fuel flow thrsugh idle fuel passage :- 30. When solenoid coil 108 is energized, the metering . apparatus is moved to the lean position determined by engagement of metering valve 102 with supplementary metering orifice 22. In the lean position, metering valve 102 obstructs fuel flow through supplementary ~., :
:
z . 7 ` metering orifice 22 while bleed valve 98 permits air flow through bleed passage 46 into idle fuel passage 30 and thus restricts fuel flow through idle fuel passage 30.
It is contemplated that coil 108 will be energized at a frequency of about 10 Hz according to . a duty cycle determined by a sensor measuring the air-fuel ratio of the mixture created by carburetor 10 -- such as a sensor measuring the oxygen content of the engine exhaust gases -- and accordingly will engage metering valve 102 with supplementary metering orifice 22 for a portion of the duty cycle and allow - spring 104 to engage bleed valve 98 with boss 64 for : the remainder of the duty cycle. Thus during operation, the carburetor metering apparatus will es~ablish an effective fuel flow through main fuel passage 24 which is a time average of a minimum flow determined by the vacuum signal in venturi cluster 28 and the area available for fuel flow through primary metering orifice 20 and a maximum flow determined by the vacuum - signal in venturi cluster 28 and the area available for fuel flow through both primary metering orifice 20 and supplementary metering orifice 22. ~ change in the duty cycle modifies the time average to establish a new effective fuel flow and accordingly changes the ~ air-fuel ratio of the mixture created by carburetor 10.
; 7 "~ .. -, Even though this carburetor is intended for use. in a closed loop system in which a feedback signal corrects for erxors in fuel flow, we believe the carburetor should be constructed to achieve a desired 5 change in the effective fuel flow upon a selected change in the duty cycle. ~ccordingly, a restriction 120 is disposed below supplemen~ary metering orifice 22, and a rich adjusting needle 122 is disposed in restriction 120 and provided with a threaded stem 124 10 allowing adjustment of needle 122 in restriction 120 to limit the area available for fuel flow through supplementary metering orifice 22; needle 122 is positioned to establish the high fuel flow desired through main fuel passage 24 when coil 108 is energized 15 according to a duty cycle of one particular value.
Also, a lean adjusting needle 126 is disposed in primary metering orifice 20 and has a threaded stem 128 allow-ing adjustment of needle 126 in primary metering orifice 20 to limit the area available for fuel flow 20 through primary metering orifice 20; needle 126 is positioned to establish the low fuel flow desired through main fuel passage 24 when coil 108 is energized according to a duty cycle of ano-ther particular valua.
In addition, a restriction 130 is disposed 25 in the discharge portion 70 of air bleed passage as6 An air bleed adjusting needle 132 is disposed in restriction 130 and has a threaded stem 134 allowing ' ~
.'.
`
`:`
: g adjustment of needle 132 in restriction 130 to li~it air flow through bleed passage 46 and thus control fuel flow through idle fuel passage 30; needle 132 is posi-tioned to establish the low fuel flow desired through idle fuel passage 30 when coil 108 is energized according to a selected duty cycle. Moreover, mixture adjusting needle 36 has a threaded stem 136 allowing adjus~ment of needle 36 in port 34 to li~it fuel flow through port 34; needle 36 is positioned to establish the high fuel flow desired through idle fuel passage 30 when coil 108 is energized according to a~other - selected duty cycle.
Carburetor 10 is calibrated according -to a procedure such as the following:
(1) Mixture needle 36 and air bleed adjusting needle 132 are preset to an average setting.
(2~ Coil 108 is energized with a particular duty cycle (a 100% duty cycle, for example), throttle 16 is opened to ~ a part throttle position providing an - air flow of, for example, four pounds of air per minute, and lean adjusting needle 126 is turned on its threaded stem 128 to set the low part throttle fuel flow desired at that duty cycle.
. 9 ., , . ..
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.
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, , 10 (3) Coil 108 is energized with another duty cycle (a 0% duty cycle, for example), throttle 16 is opened to a part throttle position, and rich adjust-ing needle 122 is turned on its threaded stem 124 to set the high part throttle fuel flow desired at that duty cycle.
(4) Coil 108 is energized with a particular duty cycle (a 0% duty cycle, for example), thro-ttle 16 is closed to the curb idle position shown in the drawing, . and mixture needle 36 is turned on its threaded stem 136 to set the high idle fuel flow desired at that duty cycle.
: 15 (5) Coil 108 is energized with another duty cycle (a 100% duty cycle, for example), throttle 16 is closed to the curb idle position, and air bleed adjust-ing needle 132 is turned on its threaded . 20 stem 134 to set the low idle fuel flow ~; desired at that duty cycle.
(6) One or more of the foregoing steps is repeated, other flow points are checked, and plugs 138, 140, 142 and 144 are installed to seal access to rich and lean adjusting needles 122 and 126, air bleed adjusting needle 132 and mixture ~: . needle 36.
.,~
Thereafter carburetor 10 wil]. provide the desired change in fuel flow with a particular change in the duty cycle, .~ thereby permitting fin~ control over fuel flow and : assuring a low gain, stable control system that avoids substantially overshooting the desired fuel flow when ;~ . changing the duty cycle~
~``
' ' ~,'J,~
This invention relates to a carburetor particularly suitable for operation in a closed loop fuel system.
Several carburetors have been proposed for . .
the purpose of creating an air~fuel mixture of sub-; stantially constant (usually stoichiometric) air-fuel ratio for an internal combustion engine. In general, it has been contemplated that such a carburetor would be used in a closed loop system having a sensor which, for example, measures the oxygen content of the engine exhaust gases as an indication of the air-fuel ratio of the mixture created for the engine and which initiates a feedback signal causing the carburetor to create a mixture of the desired air-fuel ratio.
Certain carburetors proposed for that application have an electronically controlled device which drives fuel metering apparatus between rich and lean positions according to a pulse width modulated duty cycle to maintain the metering apparatus in the ` ~ lean position for a portion of the duty cycle ana in - the rich position for the remainder of the duty cycle.
The carburetor thus duty cycle modulates the fuel flow between a maximum and a minimum and then averages the 25 maximum and minimum fuel flows to create a mixture of the desired air-fuel ratio.
', ' :
:
one such carburetor, in particular, has a main fuel passage containing a primary metering orifice and a supplementary metering orifice. The metering apparatus has a valve controlling the supplementary metering orifice and is driven, between a rich position permitting fuel flow through the supplementary orifice and a lean position obstructing fuel flow through the supplementary orifice, by a solenoid coil energized according to a pulse width modulated duty cycle. Under control of a feedback signal, the solenoia coil is energized according to the duty cycle which results in a mixture of the desired air-fuel ratio. Among the advantages some perceive for such a system is the ability to loosen tolerances on the metering area of the primary and supplementary orifices, for in such a system fuel flow is controlled by the feedbac~ signal and errors in fuel flow are corrected by the feedback ; signal.
This invention provides a carburetor of that ; 20 type having structure which improves its suitability for duty cycle modulation of the fuel flow and thus enhances its suitability for operation in a closed loop fuel system.
This invention is founded upon the discovery that, in such a carburetor, the change in fuel flow which results from a change in the duty cycle should be carefully established; that is, we believe a desired ~`~
~Z~92 ' high fuel flow should occur at a duty cycle of one partlcular value and a desired low fuel flow should occur at a duty cycle of another particular value so that a deslred fuel flow band width is achieved over the selected range of duty cycles between those parkicular valuesO
~ Accordingly, this invention provides a ;j~ carbu~etor in which the main fusl passage contains a primary metering orifice and a supplementary metering orifice and in which a valve controlling the ~ supplementary metering orifice forms part of metering ; apparatus that is driven, between a rich position permitting fuel flow through the supplementary orifice and a lean position obstructing fuel flow through the supplementary orifice, by a solenoid coil energized according to a duty cycle. The carburetor provided by this invention further includes a rich adjusting needle which limits fuel flow through the supplementary orifice to establish the high fuel flow desired at one particular value of the duty cycle and further includes a lean adjusting needle which limits fuel flow through the primary orifice to establish the low fuel flow desired at another particular value of the duty cycle.
Thus with the carburetor provided by this invention, a desired fuel flow band width may be achieved over a selected range of duty cycles.
' ~Z~2 The details as well as other features and advantages of this invention are set forth in the following description of a preferred embodiment and . are shown in the drawing in which the sole figure is ~ 5 a schematic view of the main and idle metering systems - o a carburetor employing this invention.
~: Referring to the drawing, an internal combustion engine carburetor 10 has an air induction passage 12 controlled by a choke 14 and a throttle 16.
; 10 A fuel bowl 18 delivers fuel through a primary main metering orifice 20 and a supplementary main metering orifice 22 into a main fuel passàge 24 which discharges through a nozzle 26 into a venturi cluster 28 disposed in induction passage 12.
An idle fuel passage 30 has a pick-up tube 32 extending iiltO main uel passage 24, an idle discharge port 34 opening into induction passag~. 12 past a mixture adjusting needle 36, and an off-idle port 38 opening into induction passage 12 adjacent throttle 16.
The usual side idle air bleed 40 and lower idle air bleed 42 open into idle fuel passage 30 on -~ opposite sides of a~ idle channel restrlction 44, and an air bleed passage 46 extends to the upper portion 25 48 of idle fuel passage 30. Air bleed passage 46 ~,.
J ~2~l~32 includes an inlet portion 50 having sections 52 and 54 . extending through a housing 56 to an annular region 58 . and a discharge portion 60 which includes a section 62 opening through a boss 64 surrounded by annular region 58 and sections 66 and 68 which lead through housing 56 to a - section 70 opening into idle fuel passage 30.
~ Housing 56 has a bore 72 supporting the steel .~ casing 74 of a solenoid coil assembly 76. The upper end of casing 74 has tabs 78 bent over a steel end plate 80.
A domed stainless steel spring washer 82 reacts against end plate 80 and pushes a spool 84 downwardly against .. ; a shoulder 86 of casing 74, a flange 88 of a steel end member 90 being sandwiched therebetween.
Spool 84 includes an extension 92 which reaches upwardly to guide a nickel plated steel armature 94.
A rubber seal member 96 surrounds extension 92.
The upper end of armature 94 carries a VITON* tip 98 forming a bleed valve which seats across boss 64 to control air flow through bleed passage 46, . ~20 from annular region 58 to section 62. The lower end .of armature 94 receives a stainless steel push rod 100 having a stainless steel metering valve 102 at its lower end. A stainless steel spring 104 is secured -in a groove about metering valve 102 and seats against a shoulder 106 at the lower end of casing 74 to bias * trade mark , . . .
1~2~9~
metering valve 102 away from supplemèntary metering orifice 22 and, acting through push rod 100, to engage bleed valve 98 across boss 64.
When a coil 108 wound on spool 84 is ener-gized, armature 94 is drawn downwardly against the bias of spring 104 to disengage bleed valve 98 from : boss 64 and to engage metering valve 102 in supple-mentary metering orifice 22.
; An adapter 110 is pressed on the lower tip 10 112 of casing 74 and pQsitions a sealing ring 114 in : the enla~ged bore 116 of a boss 118 disposed in the floor of fuel bowl 18. Sealing ring 114 compensates for minor misalignment between boss 118 and housing 56.
In operation, the metering apparatus 15 (metering valve 102, armature 94 and bleed valva 98~
: is biased upwardly by spring 104 to the rich position shown in the drawing, determined by engagement of bleed valve 98 with boss 64. In the rich position, metering valve 102 permits fuel flow through supple-; 20 mentary metering orifice 22 while bleed valve 98 obstructs air flow through bleed passage 46 and thus : permits increased fuel flow thrsugh idle fuel passage :- 30. When solenoid coil 108 is energized, the metering . apparatus is moved to the lean position determined by engagement of metering valve 102 with supplementary metering orifice 22. In the lean position, metering valve 102 obstructs fuel flow through supplementary ~., :
:
z . 7 ` metering orifice 22 while bleed valve 98 permits air flow through bleed passage 46 into idle fuel passage 30 and thus restricts fuel flow through idle fuel passage 30.
It is contemplated that coil 108 will be energized at a frequency of about 10 Hz according to . a duty cycle determined by a sensor measuring the air-fuel ratio of the mixture created by carburetor 10 -- such as a sensor measuring the oxygen content of the engine exhaust gases -- and accordingly will engage metering valve 102 with supplementary metering orifice 22 for a portion of the duty cycle and allow - spring 104 to engage bleed valve 98 with boss 64 for : the remainder of the duty cycle. Thus during operation, the carburetor metering apparatus will es~ablish an effective fuel flow through main fuel passage 24 which is a time average of a minimum flow determined by the vacuum signal in venturi cluster 28 and the area available for fuel flow through primary metering orifice 20 and a maximum flow determined by the vacuum - signal in venturi cluster 28 and the area available for fuel flow through both primary metering orifice 20 and supplementary metering orifice 22. ~ change in the duty cycle modifies the time average to establish a new effective fuel flow and accordingly changes the ~ air-fuel ratio of the mixture created by carburetor 10.
; 7 "~ .. -, Even though this carburetor is intended for use. in a closed loop system in which a feedback signal corrects for erxors in fuel flow, we believe the carburetor should be constructed to achieve a desired 5 change in the effective fuel flow upon a selected change in the duty cycle. ~ccordingly, a restriction 120 is disposed below supplemen~ary metering orifice 22, and a rich adjusting needle 122 is disposed in restriction 120 and provided with a threaded stem 124 10 allowing adjustment of needle 122 in restriction 120 to limit the area available for fuel flow through supplementary metering orifice 22; needle 122 is positioned to establish the high fuel flow desired through main fuel passage 24 when coil 108 is energized 15 according to a duty cycle of one particular value.
Also, a lean adjusting needle 126 is disposed in primary metering orifice 20 and has a threaded stem 128 allow-ing adjustment of needle 126 in primary metering orifice 20 to limit the area available for fuel flow 20 through primary metering orifice 20; needle 126 is positioned to establish the low fuel flow desired through main fuel passage 24 when coil 108 is energized according to a duty cycle of ano-ther particular valua.
In addition, a restriction 130 is disposed 25 in the discharge portion 70 of air bleed passage as6 An air bleed adjusting needle 132 is disposed in restriction 130 and has a threaded stem 134 allowing ' ~
.'.
`
`:`
: g adjustment of needle 132 in restriction 130 to li~it air flow through bleed passage 46 and thus control fuel flow through idle fuel passage 30; needle 132 is posi-tioned to establish the low fuel flow desired through idle fuel passage 30 when coil 108 is energized according to a selected duty cycle. Moreover, mixture adjusting needle 36 has a threaded stem 136 allowing adjus~ment of needle 36 in port 34 to li~it fuel flow through port 34; needle 36 is positioned to establish the high fuel flow desired through idle fuel passage 30 when coil 108 is energized according to a~other - selected duty cycle.
Carburetor 10 is calibrated according -to a procedure such as the following:
(1) Mixture needle 36 and air bleed adjusting needle 132 are preset to an average setting.
(2~ Coil 108 is energized with a particular duty cycle (a 100% duty cycle, for example), throttle 16 is opened to ~ a part throttle position providing an - air flow of, for example, four pounds of air per minute, and lean adjusting needle 126 is turned on its threaded stem 128 to set the low part throttle fuel flow desired at that duty cycle.
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, , 10 (3) Coil 108 is energized with another duty cycle (a 0% duty cycle, for example), throttle 16 is opened to a part throttle position, and rich adjust-ing needle 122 is turned on its threaded stem 124 to set the high part throttle fuel flow desired at that duty cycle.
(4) Coil 108 is energized with a particular duty cycle (a 0% duty cycle, for example), thro-ttle 16 is closed to the curb idle position shown in the drawing, . and mixture needle 36 is turned on its threaded stem 136 to set the high idle fuel flow desired at that duty cycle.
: 15 (5) Coil 108 is energized with another duty cycle (a 100% duty cycle, for example), throttle 16 is closed to the curb idle position, and air bleed adjust-ing needle 132 is turned on its threaded . 20 stem 134 to set the low idle fuel flow ~; desired at that duty cycle.
(6) One or more of the foregoing steps is repeated, other flow points are checked, and plugs 138, 140, 142 and 144 are installed to seal access to rich and lean adjusting needles 122 and 126, air bleed adjusting needle 132 and mixture ~: . needle 36.
.,~
Thereafter carburetor 10 wil]. provide the desired change in fuel flow with a particular change in the duty cycle, .~ thereby permitting fin~ control over fuel flow and : assuring a low gain, stable control system that avoids substantially overshooting the desired fuel flow when ;~ . changing the duty cycle~
~``
' ' ~,'J,~
Claims (2)
1. A carburetor comprising a fuel passage containing a primary metering orifice and a supplementary metering orifice and wherein fuel flow is determined in part by the area available for fuel flow through said metering orifices, and a metering apparatus reciprocable between a lean position and a rich position and includ-ing a metering valve for obstructing the fuel flow area of said supplementary metering orifice in said lean position and for opening the fuel flow area of said supplementary metering orifice in said rich position, said metering apparatus also including means for main-taining said valve in said lean position during a portion of a duty cycle and in said rich position during the remainder of the duty cycle and thereby for establishing an effective fuel flow through said passage which is a time average of a minimum flow determined in part by the area available for fuel flow through said primary metering orifice and a maximum flow determined in part by the area available for fuel flow through both said metering orifices, whereby the effective fuel flow through said passage may be changed by changing the value of said duty cycle, and wherein said carburetor further comprises a rich adjusting member limiting the area available for fuel flow through said supplementary metering orifice for establishing a certain high effective fuel flow through said passage when said duty cycle is at one particular value, and a lean adjusting member limiting the area available for fuel flow through said primary metering orifice for estab-lishing a certain low effective fuel flow through said passage when said duty cycle is at another particular value, whereby the desired fuel flow band width between said high fuel flow and said low fuel flow is achieved over the selected range of duty cycles between said particular values.
2. A carburetor comprising an induction passage through which an air flow is directed, a venturi in said induction passage creating a subatmos-pheric pressure signal indicative of the rate of air flow through said induction passage, a fuel passage containing a primary metering orifice and a supple-mentary metering orifice and extending to said venturi and wherein fuel flow is determined in part by said venturi signal and in part by the area available for fuel flow through said metering orifices, a metering apparatus reciprocable between a lean position and a rich position and including a solenoid armature, and a solenoid coil energized according to a duty cycle which maintains said metering apparatus in said lean position during a portion of the duty cycle and in said rich position during the remainder of the duty cycle, said metering apparatus also including means for obstructing the fuel flow area of said supplementary metering orifice in said lean position and for opening the fuel flow area of said supplementary metering orifice in said rich position and thereby for establishing an effective fuel flow through said fuel passage which is a time average of a minimum flow determined by said venturi signal and the area available for fuel flow through said primary metering orifice and a maximum flow determined by said venturi signal and the area available for fuel flow through both said metering orifices, whereby the ratio of said effective fuel flow through said fuel passage to the rate of air flow through said induction passage may be changed by changing the value of said duty cycle, and wherein said carburetor further comprises a rich adjust-ing member limiting the area available for fuel flow through said supplementary metering orifice for establish-ing a certain high effective fuel flow through said fuel passage when said duty cycle is at one particular value, and a lean adjusting member limiting the area available for fuel flow through said primary metering orifice for establishing a certain low effective fuel flow through said fuel passage when said duty cycle is at another particular value, whereby the desired band width for the effective fuel flow through said fuel passage between said low fuel flow and said high fuel flow is achieved over the selected range of duty cycles between said particular values.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86945478A | 1978-01-16 | 1978-01-16 | |
| US869,454 | 1978-01-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1102192A true CA1102192A (en) | 1981-06-02 |
Family
ID=25353577
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA317,616A Expired CA1102192A (en) | 1978-01-16 | 1978-12-08 | Carburetor |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS54102427A (en) |
| CA (1) | CA1102192A (en) |
| DE (1) | DE2855672A1 (en) |
| FR (1) | FR2424417A1 (en) |
| GB (1) | GB2012368B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3027441A1 (en) * | 1979-07-27 | 1981-02-12 | Colt Ind Operating Corp | DEVICE AND SYSTEM FOR CONTROLLING THE FUEL-AIR RATIO FROM A MIXTURE FEEDED BY AN INTERNAL COMBUSTION ENGINE |
| CA1150384A (en) * | 1980-02-26 | 1983-07-19 | Charles F. Lloyd | Remotely controlled servo device for controlling fluid flow |
| JPS56124655A (en) * | 1980-03-05 | 1981-09-30 | Hitachi Ltd | Air-fuel ratio compensating apparatus for carburetor |
| JPS56151247A (en) * | 1980-04-25 | 1981-11-24 | Nippon Carbureter Co Ltd | Carburetor |
| MX152641A (en) * | 1981-10-08 | 1985-10-02 | Colt Ind Operating Corp | IMPROVEMENTS TO THE FUEL METER SYSTEM FOR AN INTERNAL COMBUSTION ENGINE |
| JPS58139552U (en) * | 1982-03-16 | 1983-09-20 | マツダ株式会社 | Engine air-fuel ratio adjustment carburetor |
| IT1168696B (en) * | 1983-11-08 | 1987-05-20 | Weber Spa | DEVICE FOR TEMPORARILY ENRICHING THE MIXTURE DELIVERED BY AN INTERNAL COMBUSTION ENGINE CARBURETOR |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3409277A (en) * | 1966-06-24 | 1968-11-05 | Acf Ind Inc | Metering jet adjustable fuel by-pass |
| US3540660A (en) * | 1967-10-27 | 1970-11-17 | Atom Auto Pecas Ltda | Fuel inlet vaporizers for carburators |
| US3939654A (en) * | 1975-02-11 | 1976-02-24 | General Motors Corporation | Engine with dual sensor closed loop fuel control |
-
1978
- 1978-12-08 CA CA317,616A patent/CA1102192A/en not_active Expired
- 1978-12-13 GB GB7848318A patent/GB2012368B/en not_active Expired
- 1978-12-21 DE DE19782855672 patent/DE2855672A1/en not_active Withdrawn
-
1979
- 1979-01-11 JP JP106779A patent/JPS54102427A/en active Pending
- 1979-01-16 FR FR7900943A patent/FR2424417A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FR2424417A1 (en) | 1979-11-23 |
| GB2012368A (en) | 1979-07-25 |
| GB2012368B (en) | 1982-03-24 |
| DE2855672A1 (en) | 1979-07-19 |
| JPS54102427A (en) | 1979-08-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |