CA1090667A - Carburetor - Google Patents
CarburetorInfo
- Publication number
- CA1090667A CA1090667A CA302,691A CA302691A CA1090667A CA 1090667 A CA1090667 A CA 1090667A CA 302691 A CA302691 A CA 302691A CA 1090667 A CA1090667 A CA 1090667A
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- metering
- bracket
- air
- idle
- 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
- 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
- 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
-
- 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)
- Fuel-Injection Apparatus (AREA)
Abstract
CARBURETOR
Abstract of the Disclosure A carburetor main metering rod is operated by a bracket carried on a vacuum motor or a solenoid armature to control fuel flow through a main fuel passage, and a bleed valve floats on and is operated by the bracket to control air flow to and thus fuel flow through an idle fuel passage. A
gage measures the relative position of the bleed valve within an air bleed body to permit proper calibration of the carburetor.
Abstract of the Disclosure A carburetor main metering rod is operated by a bracket carried on a vacuum motor or a solenoid armature to control fuel flow through a main fuel passage, and a bleed valve floats on and is operated by the bracket to control air flow to and thus fuel flow through an idle fuel passage. A
gage measures the relative position of the bleed valve within an air bleed body to permit proper calibration of the carburetor.
Description
- - -This invention relates to a carburetor particular~y suitable for operation in a closed loop fuel control system.
Sever~l carburetors have been proposed for the purpose of creating an air-fuel mixture of substantially constant (usually stoichiometric) air-fuel ratio for an internal combustion engine. In general, it has been contem-plated that such a carburetor would be used in a closed loop system having a sensor -- such as a sensor that measures the oxygen content of the engine exhaust gases as an indication of the air-fuel ratio of the mixture created by the carburetor --which would initiate a feedback signal causing the carburetor to create a mixture of the desired air-fuel ratio.
Certain carburetors proposed for that application had a main metering valve operated to create a part throttle mixture of the desired air-fuel ratio but had no idle metering apparatus which could be operated to create an idle mixture of the desired air-fuel ratio. Other carburetors proposed for that application had an idle bleed valve operated to create an idle mixture of the desired air-fuel ratio, but the idle bleed valve had an actuator .,.,~ ~, 0~;7 separate from the actuator for the main metering apparatus and thus involved potentially high cost, complexity, response time and space requirements.
This invention provides a carburetor which, in the preferred embodiments, has a main metering rod operated ~y a bracket carried either by a solenoid armature or by a vacuum motor to create the desired part throttle mixture and also has an idle bleed valve that flots on and is operated by the same bracket to create the desired idle mixture. The main metering rod and idle bleed valve thus are operated by a common actuator, and yet the fuel metering orifice controlled by the metering rod need not be precisely aligned with the air bleed metering area controlled by the bleed valve. This invention accordingly provides a carburetor of minimized complexity, cost, response time and space requirements as well as a carburetor which may be readily calibrated.
The details as well as other features and advantages of this invention are set forth in the following description of several embodiments and are shown in the drawings in which:
Figure 1 is a schematic view of the main metering system of a car~uretor employing this invention;
Figure 2 is a schematic view of the idle system of the Figure 1 carburetor;
Figure 3 is a sectional view of a regulator which creat~s a regulated vacuum signal:
Figure 4 is a sectional view of a solenoid valve ~' which receives the regulated vacuum signa~ and provides a ,1090~;7 :. control vacuum signal to the Figure 1 carburetor;
Figure 5 is a view of a portion of the Figure 1 carburetor showing a gage for adjusting the air bleed body relative to the bleed valve;
Figure 6 is a greatly enlarged view of the air bleed ~ody and the bleed valve;
Figure 7 is a schematic sectional view of a similar carburetor in which the metering rod and bleed valve are operated by a solenoid armature;
10Figure 8 is a schematic sectional viow of a similar :
carburetor in which the metering rod and bleed valve are operated by a diaphragm vacuum motor; and Figure 9 is a schematic view of an embodiment of this invention .
Referring first to Figures 1 and 2, an internal combustion engine carburetor 10 has an air horn section lOa, a fuel bowl section lOb and a throttle body section lOc which define an air induction passage 12 controlled by a throttle 14.
Within fuel bowl section lOb, a fuel bowl 16 delivers fuel through a main metering orifice 18 into a main fuel passage 20 which discharges through a nozzle 22 into a venturi cluster 24 disposed in induction passage 12.
As shown in Figure 2, an idle fuel passage 26 has a ~`
pickup tube 28 extending into main fuel passage 20, an off-idle port 3~ opening into induction passage 12 adjacent thrott~e 14, and an idle discharge port 32 opening into induction passage 12 past a threaded adjustable mixture needle 33.
A tapered main metering rod 34 is disposed in orifice 18 and is suspended from a horizontally disposed brac~et 36 carried by a piston 38. A spring 40 biases piston 38, ~rac~et b7 " 36 and metering rod 34 upwardly toward a rich position to permit increased fuel flow through main metering orifice 18 and main fuel passage 20. Piston 38, bracket 36 and metering rod 34 are drawn downwardly toward a lean position by a control vacuum ~ignal applied through a passage 42 to restrict fuel flow through main metering orifice 18 and main fuel pas~age 20.
A vacuum regulator 44 senses the manifold vacuum at a port 46 in induction passage 12 downstream of throttle 14 and provides a regulated vacuum ~ignal to a solenoid valve 48.
So~enoid valve 48 is energized by an electronic package 50 to control the vacuum signal applied through passage 42 to piston 38, As shown in Figure 3, regulator 44 has a fitting 44a for sensing the manifold vacuum at port 46 and a fitting 44b for delivering a regulated vacuum signal to solenoid valve 48.
A diaphragm 44c carrying a valve member 44d is biased right-wardly by a ~pring 44e to permit application of manifold vacuum to a chamber 44f. When the vacuum in chamber 44f reaches a selected value, diaphragm 44c moves leftwardly against the bias 20 of spring 44e and valve 44d engage~ the end of fitting 44a to S
preclude further application of vacuum to chamber 44f. Should the vacuum in chamber 44f drop below the selected value, spring 44e will displace diaphragm 44c and valve 44d rightwardly to expose cham~er 44f to manifold vacuum. It will be noted that fitting 44a is threaded to permit adjustment of the regu-lated vacuum maintained by regulator 44.
As shown in Figure 4, solenoid valve 48 includes a fitting 48a for receiving the regulated vacuum signal from regulator 44, a fitting 48b for receiving clean air at sub-30 stantlally atmospheric pressure, and a fitting 48c for delivering a control vacuum signal through passage 42 to piston 38.
-- , 10~0~7 Solenoid valve 48 is similar to that shown in US patent 4,005,733 and thus i~ described only briefly here. Solenoid valve 48 has a disc valve member 48d which i~ biased by a spring 48e to engage across air inlet fitting 48b and which is displaced against the bias of spring 48e to engage across regulated vacuum fitting 48a upon energization of a solenoid coil 48f. When solenoid coil 48f is energized, disc valve element 48d allows a~r flow from fitting 48b to fitting 48c to decrease the control vacuum ~ignal applied to piston 38 and allow gpring 40 to move piston 38, bracket 36 and metering rod 34 toward the rich position. When solenoid coil 48f is deenergized, spring 48e moves disc valve element 48d to apply the regulated vacuum signal from fitting 48a through fitting 48c to increase the control vacuum signal applied to piston 38 and move piston 38, bracket 36 and metering rod 34 toward the lean po6ition It is contemplated that electronic package 50 will energize coil 4~f according to a duty cycle determined by a sensor measuring the air-fuel ratio of the mLxture created by carburetor 10 -- such as a sensor measuring the oxygen content of the engine exhaust gases -- and accordingly will seat disc valve member 48d across regulated vacuum fitting 48a or allow disc valve member 48d to seat across air inlet fitting 48b for periods of time which create a control vacuum signal tending to maintain the mixture created by carburetor 10 at a stoichio-metric air-fuel ratio or any other desired air-fuel ratio.
As shown in Figures 1, 2, 5 and 6, an air bleed body 52 has a flange 53 threaded into air horn section lOa ab~Ye bracket 36 and has small and large bores 54 and 56 aligned with bracket 36. Large bore 56 is exposed through a Yent 58 to a source of air at substantially atmospheric pressure, -t;7 :~ while a cross drilling 60 connects with small bore 54 and forms part of an air bleed pi~sage 62 which opens into idle fuel passage 26 along withJ~top idle air bleed 62a upstream of idle channel restrictor 6~ and lower idle air bleed 62b down-stream of restrictor 63. ~i/
The opening of small bore 54 from large bore 56 defines a metering area 64 controlled by the taper 66 of an idle bleed valve 68. ~leed valve 68 ha~ a nose 70 guided in small bore 54 and a flange 72 guided in large bore 56; flange 72 has a generally triangular configuration to penmit air flow there-past.
The tail 74 of bleed valve 68 floats on the top of bracket 36 and is biased to engage and follow bracket 36 ~y a light spring 76. A clip 78 is disposed in a groove 80 about the bottom of air bleed body 52 and has a projection 82 -, extending into large bore 56 to retain bleed valve 68 during assembly. If desired, a slider (not shown) may surround tail 74 to i~hibit passage of fluid from fuel bowl 16 about tail 74.
An adjusting screw 84 is disposed adjacent piston 38 and has a lower shoulder 86 forming a lean stop which is engaged by a pin 88 carried by piston 38 to limit movement of the metering apparatus (metering rod 34, bracket 36, piston 38 and bleed valve 68) in the lean direction and an upper shoulder 90 forming a rich stop which is engaged by pin 88 to limit movement of the metering apparatus in the rich direction.
In operation, when the mixture created by carburetor 10 contains excess fuel, electronic package ~0 decreases the 3~ energizing duty cycle of solenoid valve 48, causing an increase in the control vacuum signal applied through passage 42 to lO~fj~;7 pi~ton 38; piston 38 and bracket 36 then are drawn downwardly toward lean stop 86, causing metering rod 34 to restrict fuel flow through main metering orifice 18 and main fuel passage 20 and allowing spring 76 to lower bleed valve 68 permitting increased air flow through metering area 64 and air bleed passage 62 to idle fuel passage 26 and thereby restricting fuel flow through idle fuel passage 26. When the mixture con-tains insufficient fuel, electronic pac~age 50 increases the duty cycle of solenoid valve 48, causing a reduction in the control vacuum signal applied through passage 42 to piston 38: spring 40 then lifts piston 38 and bracket 36, thereby lifting metering rod 34 to permit increased fuel flow through main metering orifice 18 and main fuel passage 20 and lifting bleed valve 68 to restrict air flow through metering area 64 and air bleed passage 62 to idle fuel passage 26 and thereby permit increased fuel flow through idle fuel passage 26.
It will be appreciated that during wide open throttle operation when manifold vacuum drops and the pressure at port 46 approaches atmospheric pressure, vacuum regulator 44 and piston spring 40 may be calibrated in such a manner that the available vacuum would be insufficient to retract piston 38 away from rich stop 90 even if electronic pacXage 50 were to demand that solenoid valve 48 apply full manifold vacuum through pa~sage 42 to piston 38.
Referring to Figure 5, carburetor 1~ i9 calibrated by moving air bleed body outwardly as far as practical by turn~ng it on its threaded flange 53,displacing mixture needle 33 a selected number of turn~ from port 32, engaging piston pin 88 with lean stop 86, adjusting the position of screw 84 to establish the proper position of metering rod 34 in main metering orifice 18 and thus set the lean authority for part ~., .
throttle operation, and adjusting the position of mixture needle 33 in port 32 to set the lean authority for curb idle operation. Piston pin 88 is then brought into engage-ment with rich stop 90, a gage pin 91 is inserted in small bore 54 to engage the nose 70 of bleed valve 68, and a gage housing 92 i8 brought into engagement with the end of air bleed body 52. The tip 93 of gage housing 92 fits in a slot 94 on the end of bleed valve body 52. Gage housing 92 is then rotated to turn bleed body 52, thus raising or lowering bleed body S2 until scribe marks on gage housing 92 indicate that metering area 64 i8 properly positioned relative to bleed valve 68.
A retainer 95 in the upper portion of gage housing 92 prevents withdrawal of pin 91 from housing 92.
After adjustment of valve body 52 within carburetor 10, small bore 54 i~ closed w~th a plug 96 a~ shown in F~gures 1 and 2.
F~gure 7 shows an alternative embodiment 100 which is similar in most respects to carburetor 10, and identical parts are designated with the same numerals. In carburetor 100, however, bracket 136 is operated by the armature 102 of a solenoid coil 104 which is energized by an electronic package 150.
Figure 8 shows yet an~ther embodiment 20~ which is sim~lar in many respects to carb~retor 10, and identical parts are also designated with the same numerals. In this embodiment, however, the piston 238 guides the bracket 236 but does not impart motion thereto. Instead, a link 201 is mounted on a pivot 203 and has a pi~otal connection 205 with 3~ bracket 236. Bracket 236 is biased in the rich direction by a spring 207 which acts on link 20~ through a ~tem 20g .
lt)~O~i~;7 and i8 drawn in the lean direction by a diaphragm 211 which acts through stem 209 and link 201 in response ~o a control vacuum signal received through a vacuum passage 242 from solenoid valve 48. A threaded stop 286 limits movement of diaphragm 211, stem 209, link 201, and bracket 236 in the lean direction, while a shoulder 290 on an adjusting screw 284 is engaged by a pin 288 carried by piston 238 to limit move-ment of bracket 236 in the rich direction.
In the embodiments of both Figure 7 and Figure 8, the tail 74 of bleed valve 68 floats on the bracket 136 or 236, and bleed valve 68 is operated simultaneously with metering rod 34.
Figure 9 shows an improved embodiment in which the carburetor 310 has an air induction passage 312 controlled by a choke 314 and a throttle 316. A fuel bowl 318 delivers fuel through a main metering orifice 320 into a main fuel pa~sage 322 which discharges through a nozzle 324 into a venturi clu~ter 326 disposed in induction passage 312.
An idle fuel passage 328 has a pick-up tube 330 extending into main fuel passage 322, an idle discharge port 332 opening into induction passage 312 past a threaded adjustable mixture needle 334, and an off-idle port 336 opening into induction pa~sage 312 ad~acent throttle 316.
A stainless ~teel stepped main metering rod 338 is supported in orifice 320 by a stainless steel guide 340 and is biased upwardly by a spring 342 to engage a horizontally dis-posed stainless steel bracket 344.
An idle air bleed passage 346 extends from an inlet 348 to the upper portion 349 of idle fuel passage 328 and includes an annulus 350 about a stainless steel air bleed body 3S2, upper ports 354, an axial bore 356 and lower ports 358 in t~ 7 air bleed body 352, a second annulus 360 about air bleed body 352, and a lower section 362 opening into idle fuel passage 328 along with top idle air bleed 362a upstream of an idle channel restrictor 363 and a lower idle air bleed 362b down-stream of restrictor 363. A stainless steel idle bleed valve 364 is disposed in bore 356 to traverse the metering area defined by the opening of lower ports 358 from bore 356 and is biased by a spring 366 so that its tail 368 floats on bracket 344.
Bracket 344 is pressed onto and carried by a stainless steel tip 369 which is pressed onto and forms a part of a nic~el plated steel solenoid armature 370. Bracket 344 and armature 370 are biased upwardly by a stainless steel spring 372 to engage tip 369 with the head of a rich stop 374. Spring 372 is retained in an annular recess on a steel sleeve 375.
Armature 370 is received in and guided by a spool 376 forming a portion of a solenoid coil assembly 378. A coil 380 is wound on spool 376 and is surrounded by a cupped steel case 382. The upper end of case 382 has three tangs 384 which ~-are bent over a steel end plate 386 into which sleeve 375 is pressed. A domed stainless steel spring washer 388 is disposed between the lower end of spool 376 and the lower end of case 382 to bias spool 376 upwardly toward end plate 386, compressing an insulation washer 389 therebetween.
Solenoid coil assembly 378 has a steel end member 390, pressed into and staked to case 382, which ~orms a conical air gap with the lower end 392 of armature 370. End member 390 has a projection 394 extending through case 382 and guided in a boss 3~6 to locate coil assembly 378 within fuel bowl 318.
All steel parts of solenoid coil assembly 378 are zinc dichromated for immersion in fuel bowl 318, and it will be noted that case 382 has a hole 398 and spool 376 has an aperture 400 which permit fuel to circulate within spool 376 about armature 370. Proper operation has been achieved when a fuel filter (not shown) is provided at the carburetor inlet to screen out particles larger than 0.075 mm and the diametral working clearance between spool 376 and armature 370 is between O.20 and 0.43 mm.
A spring 402 biases solenoid coil assembly 378 up-wardly so that end plate 386 engages the shoulder 403 of a lean ~top 404. A spring 406 surrounds the threaded stem 408 of lean stop 404 to inhibit changes in the setting of lean stop 404 due to vibration.
Bracket 344 is bifurcated at 410 to surround an extended shank 412 on lean stop 404. Shank 412 thus prevents rotation of armature 370 and bracket 344.
In operation, the metering apparatus ~met~rin~ rod 338, bracket 344, armature 370 and bleed valve 364) is biased up-wardly by springs 342 and 372 to the rich position determinedby engagement of armature tip 369 with rich stop 374. In the rich position, the reduced tip 414 of metering rod 338 is dis-posed in metering orifice 320 to permit increased fuel fLow from fuel bowl 318 through metering orifice 320, main fuel passage 322 and nozzle 324 to induction passage 312, while bleed ~alve 364 obstructs ports 358 to inhibit air flow through bleed passage 346 and thus permit increased fuel flow through idle fuel passage 328 to induction passage 312. When solenoid coil 380 is energized, the metering apparatus is moved to the t ean position established by adjustment of lean stop 404. In the ~ .
10'3~ 7 lean position, the enlarged step 416 of metering rod 338 is disposed in metering orifice 320 to restrict fuel flow from fuel bowl 318 through metering orifice 320, main fuel passage 322 and nozzle 324 to induction passage 312, while bleed valve 364 exposes ports 358 to allow increased air flow through bleed passage 346 into idle fuel passage 328 and thus restrict fuel flow through idle fuel passage 328 to induction passage 312.
It is contemplated that coil 380 will be energized according to a duty cycle of about 10 Hz having a pulse width determined by a sensor measuring the air-fuel ratio of the mixture created by carburetor 310 -- such as a sensor measuring the oxygen content of the engine exhaust gases -- and accordingly will move armature 370 to the lean position for a selected portion of the duty cycle and allow spring 372 to engage armature 370 with rich stop 374 for the remainder of the duty cycle; carburetor 310 thus will pulse width modulate the fuel flow and then average high and low fuel flows to create a mixture having a stoichiometric air-fuel ratio or any other desired air-fuel ratio.
Carburetor 10 is calibrated according to the follow-ing procedure:
(1) Air bleed body 352 is moved out-wardly as far as practical by turning it on its ~ .
threaded shank 418 to expose ports 358 a~ove the end of bleed valve 364, and mixture needle 334 is displaced from port 332 a selected number of turns.
Sever~l carburetors have been proposed for the purpose of creating an air-fuel mixture of substantially constant (usually stoichiometric) air-fuel ratio for an internal combustion engine. In general, it has been contem-plated that such a carburetor would be used in a closed loop system having a sensor -- such as a sensor that measures the oxygen content of the engine exhaust gases as an indication of the air-fuel ratio of the mixture created by the carburetor --which would initiate a feedback signal causing the carburetor to create a mixture of the desired air-fuel ratio.
Certain carburetors proposed for that application had a main metering valve operated to create a part throttle mixture of the desired air-fuel ratio but had no idle metering apparatus which could be operated to create an idle mixture of the desired air-fuel ratio. Other carburetors proposed for that application had an idle bleed valve operated to create an idle mixture of the desired air-fuel ratio, but the idle bleed valve had an actuator .,.,~ ~, 0~;7 separate from the actuator for the main metering apparatus and thus involved potentially high cost, complexity, response time and space requirements.
This invention provides a carburetor which, in the preferred embodiments, has a main metering rod operated ~y a bracket carried either by a solenoid armature or by a vacuum motor to create the desired part throttle mixture and also has an idle bleed valve that flots on and is operated by the same bracket to create the desired idle mixture. The main metering rod and idle bleed valve thus are operated by a common actuator, and yet the fuel metering orifice controlled by the metering rod need not be precisely aligned with the air bleed metering area controlled by the bleed valve. This invention accordingly provides a carburetor of minimized complexity, cost, response time and space requirements as well as a carburetor which may be readily calibrated.
The details as well as other features and advantages of this invention are set forth in the following description of several embodiments and are shown in the drawings in which:
Figure 1 is a schematic view of the main metering system of a car~uretor employing this invention;
Figure 2 is a schematic view of the idle system of the Figure 1 carburetor;
Figure 3 is a sectional view of a regulator which creat~s a regulated vacuum signal:
Figure 4 is a sectional view of a solenoid valve ~' which receives the regulated vacuum signa~ and provides a ,1090~;7 :. control vacuum signal to the Figure 1 carburetor;
Figure 5 is a view of a portion of the Figure 1 carburetor showing a gage for adjusting the air bleed body relative to the bleed valve;
Figure 6 is a greatly enlarged view of the air bleed ~ody and the bleed valve;
Figure 7 is a schematic sectional view of a similar carburetor in which the metering rod and bleed valve are operated by a solenoid armature;
10Figure 8 is a schematic sectional viow of a similar :
carburetor in which the metering rod and bleed valve are operated by a diaphragm vacuum motor; and Figure 9 is a schematic view of an embodiment of this invention .
Referring first to Figures 1 and 2, an internal combustion engine carburetor 10 has an air horn section lOa, a fuel bowl section lOb and a throttle body section lOc which define an air induction passage 12 controlled by a throttle 14.
Within fuel bowl section lOb, a fuel bowl 16 delivers fuel through a main metering orifice 18 into a main fuel passage 20 which discharges through a nozzle 22 into a venturi cluster 24 disposed in induction passage 12.
As shown in Figure 2, an idle fuel passage 26 has a ~`
pickup tube 28 extending into main fuel passage 20, an off-idle port 3~ opening into induction passage 12 adjacent thrott~e 14, and an idle discharge port 32 opening into induction passage 12 past a threaded adjustable mixture needle 33.
A tapered main metering rod 34 is disposed in orifice 18 and is suspended from a horizontally disposed brac~et 36 carried by a piston 38. A spring 40 biases piston 38, ~rac~et b7 " 36 and metering rod 34 upwardly toward a rich position to permit increased fuel flow through main metering orifice 18 and main fuel passage 20. Piston 38, bracket 36 and metering rod 34 are drawn downwardly toward a lean position by a control vacuum ~ignal applied through a passage 42 to restrict fuel flow through main metering orifice 18 and main fuel pas~age 20.
A vacuum regulator 44 senses the manifold vacuum at a port 46 in induction passage 12 downstream of throttle 14 and provides a regulated vacuum ~ignal to a solenoid valve 48.
So~enoid valve 48 is energized by an electronic package 50 to control the vacuum signal applied through passage 42 to piston 38, As shown in Figure 3, regulator 44 has a fitting 44a for sensing the manifold vacuum at port 46 and a fitting 44b for delivering a regulated vacuum signal to solenoid valve 48.
A diaphragm 44c carrying a valve member 44d is biased right-wardly by a ~pring 44e to permit application of manifold vacuum to a chamber 44f. When the vacuum in chamber 44f reaches a selected value, diaphragm 44c moves leftwardly against the bias 20 of spring 44e and valve 44d engage~ the end of fitting 44a to S
preclude further application of vacuum to chamber 44f. Should the vacuum in chamber 44f drop below the selected value, spring 44e will displace diaphragm 44c and valve 44d rightwardly to expose cham~er 44f to manifold vacuum. It will be noted that fitting 44a is threaded to permit adjustment of the regu-lated vacuum maintained by regulator 44.
As shown in Figure 4, solenoid valve 48 includes a fitting 48a for receiving the regulated vacuum signal from regulator 44, a fitting 48b for receiving clean air at sub-30 stantlally atmospheric pressure, and a fitting 48c for delivering a control vacuum signal through passage 42 to piston 38.
-- , 10~0~7 Solenoid valve 48 is similar to that shown in US patent 4,005,733 and thus i~ described only briefly here. Solenoid valve 48 has a disc valve member 48d which i~ biased by a spring 48e to engage across air inlet fitting 48b and which is displaced against the bias of spring 48e to engage across regulated vacuum fitting 48a upon energization of a solenoid coil 48f. When solenoid coil 48f is energized, disc valve element 48d allows a~r flow from fitting 48b to fitting 48c to decrease the control vacuum ~ignal applied to piston 38 and allow gpring 40 to move piston 38, bracket 36 and metering rod 34 toward the rich position. When solenoid coil 48f is deenergized, spring 48e moves disc valve element 48d to apply the regulated vacuum signal from fitting 48a through fitting 48c to increase the control vacuum signal applied to piston 38 and move piston 38, bracket 36 and metering rod 34 toward the lean po6ition It is contemplated that electronic package 50 will energize coil 4~f according to a duty cycle determined by a sensor measuring the air-fuel ratio of the mLxture created by carburetor 10 -- such as a sensor measuring the oxygen content of the engine exhaust gases -- and accordingly will seat disc valve member 48d across regulated vacuum fitting 48a or allow disc valve member 48d to seat across air inlet fitting 48b for periods of time which create a control vacuum signal tending to maintain the mixture created by carburetor 10 at a stoichio-metric air-fuel ratio or any other desired air-fuel ratio.
As shown in Figures 1, 2, 5 and 6, an air bleed body 52 has a flange 53 threaded into air horn section lOa ab~Ye bracket 36 and has small and large bores 54 and 56 aligned with bracket 36. Large bore 56 is exposed through a Yent 58 to a source of air at substantially atmospheric pressure, -t;7 :~ while a cross drilling 60 connects with small bore 54 and forms part of an air bleed pi~sage 62 which opens into idle fuel passage 26 along withJ~top idle air bleed 62a upstream of idle channel restrictor 6~ and lower idle air bleed 62b down-stream of restrictor 63. ~i/
The opening of small bore 54 from large bore 56 defines a metering area 64 controlled by the taper 66 of an idle bleed valve 68. ~leed valve 68 ha~ a nose 70 guided in small bore 54 and a flange 72 guided in large bore 56; flange 72 has a generally triangular configuration to penmit air flow there-past.
The tail 74 of bleed valve 68 floats on the top of bracket 36 and is biased to engage and follow bracket 36 ~y a light spring 76. A clip 78 is disposed in a groove 80 about the bottom of air bleed body 52 and has a projection 82 -, extending into large bore 56 to retain bleed valve 68 during assembly. If desired, a slider (not shown) may surround tail 74 to i~hibit passage of fluid from fuel bowl 16 about tail 74.
An adjusting screw 84 is disposed adjacent piston 38 and has a lower shoulder 86 forming a lean stop which is engaged by a pin 88 carried by piston 38 to limit movement of the metering apparatus (metering rod 34, bracket 36, piston 38 and bleed valve 68) in the lean direction and an upper shoulder 90 forming a rich stop which is engaged by pin 88 to limit movement of the metering apparatus in the rich direction.
In operation, when the mixture created by carburetor 10 contains excess fuel, electronic package ~0 decreases the 3~ energizing duty cycle of solenoid valve 48, causing an increase in the control vacuum signal applied through passage 42 to lO~fj~;7 pi~ton 38; piston 38 and bracket 36 then are drawn downwardly toward lean stop 86, causing metering rod 34 to restrict fuel flow through main metering orifice 18 and main fuel passage 20 and allowing spring 76 to lower bleed valve 68 permitting increased air flow through metering area 64 and air bleed passage 62 to idle fuel passage 26 and thereby restricting fuel flow through idle fuel passage 26. When the mixture con-tains insufficient fuel, electronic pac~age 50 increases the duty cycle of solenoid valve 48, causing a reduction in the control vacuum signal applied through passage 42 to piston 38: spring 40 then lifts piston 38 and bracket 36, thereby lifting metering rod 34 to permit increased fuel flow through main metering orifice 18 and main fuel passage 20 and lifting bleed valve 68 to restrict air flow through metering area 64 and air bleed passage 62 to idle fuel passage 26 and thereby permit increased fuel flow through idle fuel passage 26.
It will be appreciated that during wide open throttle operation when manifold vacuum drops and the pressure at port 46 approaches atmospheric pressure, vacuum regulator 44 and piston spring 40 may be calibrated in such a manner that the available vacuum would be insufficient to retract piston 38 away from rich stop 90 even if electronic pacXage 50 were to demand that solenoid valve 48 apply full manifold vacuum through pa~sage 42 to piston 38.
Referring to Figure 5, carburetor 1~ i9 calibrated by moving air bleed body outwardly as far as practical by turn~ng it on its threaded flange 53,displacing mixture needle 33 a selected number of turn~ from port 32, engaging piston pin 88 with lean stop 86, adjusting the position of screw 84 to establish the proper position of metering rod 34 in main metering orifice 18 and thus set the lean authority for part ~., .
throttle operation, and adjusting the position of mixture needle 33 in port 32 to set the lean authority for curb idle operation. Piston pin 88 is then brought into engage-ment with rich stop 90, a gage pin 91 is inserted in small bore 54 to engage the nose 70 of bleed valve 68, and a gage housing 92 i8 brought into engagement with the end of air bleed body 52. The tip 93 of gage housing 92 fits in a slot 94 on the end of bleed valve body 52. Gage housing 92 is then rotated to turn bleed body 52, thus raising or lowering bleed body S2 until scribe marks on gage housing 92 indicate that metering area 64 i8 properly positioned relative to bleed valve 68.
A retainer 95 in the upper portion of gage housing 92 prevents withdrawal of pin 91 from housing 92.
After adjustment of valve body 52 within carburetor 10, small bore 54 i~ closed w~th a plug 96 a~ shown in F~gures 1 and 2.
F~gure 7 shows an alternative embodiment 100 which is similar in most respects to carburetor 10, and identical parts are designated with the same numerals. In carburetor 100, however, bracket 136 is operated by the armature 102 of a solenoid coil 104 which is energized by an electronic package 150.
Figure 8 shows yet an~ther embodiment 20~ which is sim~lar in many respects to carb~retor 10, and identical parts are also designated with the same numerals. In this embodiment, however, the piston 238 guides the bracket 236 but does not impart motion thereto. Instead, a link 201 is mounted on a pivot 203 and has a pi~otal connection 205 with 3~ bracket 236. Bracket 236 is biased in the rich direction by a spring 207 which acts on link 20~ through a ~tem 20g .
lt)~O~i~;7 and i8 drawn in the lean direction by a diaphragm 211 which acts through stem 209 and link 201 in response ~o a control vacuum signal received through a vacuum passage 242 from solenoid valve 48. A threaded stop 286 limits movement of diaphragm 211, stem 209, link 201, and bracket 236 in the lean direction, while a shoulder 290 on an adjusting screw 284 is engaged by a pin 288 carried by piston 238 to limit move-ment of bracket 236 in the rich direction.
In the embodiments of both Figure 7 and Figure 8, the tail 74 of bleed valve 68 floats on the bracket 136 or 236, and bleed valve 68 is operated simultaneously with metering rod 34.
Figure 9 shows an improved embodiment in which the carburetor 310 has an air induction passage 312 controlled by a choke 314 and a throttle 316. A fuel bowl 318 delivers fuel through a main metering orifice 320 into a main fuel pa~sage 322 which discharges through a nozzle 324 into a venturi clu~ter 326 disposed in induction passage 312.
An idle fuel passage 328 has a pick-up tube 330 extending into main fuel passage 322, an idle discharge port 332 opening into induction passage 312 past a threaded adjustable mixture needle 334, and an off-idle port 336 opening into induction pa~sage 312 ad~acent throttle 316.
A stainless ~teel stepped main metering rod 338 is supported in orifice 320 by a stainless steel guide 340 and is biased upwardly by a spring 342 to engage a horizontally dis-posed stainless steel bracket 344.
An idle air bleed passage 346 extends from an inlet 348 to the upper portion 349 of idle fuel passage 328 and includes an annulus 350 about a stainless steel air bleed body 3S2, upper ports 354, an axial bore 356 and lower ports 358 in t~ 7 air bleed body 352, a second annulus 360 about air bleed body 352, and a lower section 362 opening into idle fuel passage 328 along with top idle air bleed 362a upstream of an idle channel restrictor 363 and a lower idle air bleed 362b down-stream of restrictor 363. A stainless steel idle bleed valve 364 is disposed in bore 356 to traverse the metering area defined by the opening of lower ports 358 from bore 356 and is biased by a spring 366 so that its tail 368 floats on bracket 344.
Bracket 344 is pressed onto and carried by a stainless steel tip 369 which is pressed onto and forms a part of a nic~el plated steel solenoid armature 370. Bracket 344 and armature 370 are biased upwardly by a stainless steel spring 372 to engage tip 369 with the head of a rich stop 374. Spring 372 is retained in an annular recess on a steel sleeve 375.
Armature 370 is received in and guided by a spool 376 forming a portion of a solenoid coil assembly 378. A coil 380 is wound on spool 376 and is surrounded by a cupped steel case 382. The upper end of case 382 has three tangs 384 which ~-are bent over a steel end plate 386 into which sleeve 375 is pressed. A domed stainless steel spring washer 388 is disposed between the lower end of spool 376 and the lower end of case 382 to bias spool 376 upwardly toward end plate 386, compressing an insulation washer 389 therebetween.
Solenoid coil assembly 378 has a steel end member 390, pressed into and staked to case 382, which ~orms a conical air gap with the lower end 392 of armature 370. End member 390 has a projection 394 extending through case 382 and guided in a boss 3~6 to locate coil assembly 378 within fuel bowl 318.
All steel parts of solenoid coil assembly 378 are zinc dichromated for immersion in fuel bowl 318, and it will be noted that case 382 has a hole 398 and spool 376 has an aperture 400 which permit fuel to circulate within spool 376 about armature 370. Proper operation has been achieved when a fuel filter (not shown) is provided at the carburetor inlet to screen out particles larger than 0.075 mm and the diametral working clearance between spool 376 and armature 370 is between O.20 and 0.43 mm.
A spring 402 biases solenoid coil assembly 378 up-wardly so that end plate 386 engages the shoulder 403 of a lean ~top 404. A spring 406 surrounds the threaded stem 408 of lean stop 404 to inhibit changes in the setting of lean stop 404 due to vibration.
Bracket 344 is bifurcated at 410 to surround an extended shank 412 on lean stop 404. Shank 412 thus prevents rotation of armature 370 and bracket 344.
In operation, the metering apparatus ~met~rin~ rod 338, bracket 344, armature 370 and bleed valve 364) is biased up-wardly by springs 342 and 372 to the rich position determinedby engagement of armature tip 369 with rich stop 374. In the rich position, the reduced tip 414 of metering rod 338 is dis-posed in metering orifice 320 to permit increased fuel fLow from fuel bowl 318 through metering orifice 320, main fuel passage 322 and nozzle 324 to induction passage 312, while bleed ~alve 364 obstructs ports 358 to inhibit air flow through bleed passage 346 and thus permit increased fuel flow through idle fuel passage 328 to induction passage 312. When solenoid coil 380 is energized, the metering apparatus is moved to the t ean position established by adjustment of lean stop 404. In the ~ .
10'3~ 7 lean position, the enlarged step 416 of metering rod 338 is disposed in metering orifice 320 to restrict fuel flow from fuel bowl 318 through metering orifice 320, main fuel passage 322 and nozzle 324 to induction passage 312, while bleed valve 364 exposes ports 358 to allow increased air flow through bleed passage 346 into idle fuel passage 328 and thus restrict fuel flow through idle fuel passage 328 to induction passage 312.
It is contemplated that coil 380 will be energized according to a duty cycle of about 10 Hz having a pulse width determined by a sensor measuring the air-fuel ratio of the mixture created by carburetor 310 -- such as a sensor measuring the oxygen content of the engine exhaust gases -- and accordingly will move armature 370 to the lean position for a selected portion of the duty cycle and allow spring 372 to engage armature 370 with rich stop 374 for the remainder of the duty cycle; carburetor 310 thus will pulse width modulate the fuel flow and then average high and low fuel flows to create a mixture having a stoichiometric air-fuel ratio or any other desired air-fuel ratio.
Carburetor 10 is calibrated according to the follow-ing procedure:
(1) Air bleed body 352 is moved out-wardly as far as practical by turning it on its ~ .
threaded shank 418 to expose ports 358 a~ove the end of bleed valve 364, and mixture needle 334 is displaced from port 332 a selected number of turns.
(2) Coil 380 is continuously energized (100% duty cycle), throttle 316 is opened to a part throttle position providing an air flow of, - io~ 7 for example, QiX pounds of air per minute, and lean stop 404 is turned on its threaded ~tem 408 to establish the lean position of the metering apparatus and thus set the lean part throttle authority for carburetor 310.
(3) Coil 380 is continuously energized (100~ duty cycle), throttle 316 is closed to the curb idle position shown in the drawing, and mixture needle 334 i9 adjusted in port 332 to set the lean idle authority for carburetor 310.
(4) Coil 380 is deenergized (0% duty cycle), throttle 316 is opened to a part throttle position, and rich stop 374 is turned on its threaded stem 420 to establish the rich position for the metering apparatus and thus 6et the rich part throttle authority for carburetor 310.
~S) Coil 380 i8 deenergized (~% duty J
cycle), throttle 316 i8 closed to the curb idle position, and air bleed bcdy 352 is turned on its threaded shank 418 to adjust the position of body 352 relative to bleed valve 364 and thus set the rich idle authority for carburetor 310.
(6) One or more of the foregoing steps is repeated, other flow points are checked, and pluqs 422, 424, 426 and 428 are installed to seal access to adjustable rich and lean stops 374 and 404, air bleed body 352 and mixture needle 334.
Thereafter the carburetor metering apparatus will meter fuel flow between the rich authority and the lean author-10'~ ;'7 ity when coil 380 is operated at any duty cycle pulse width between 0~ and lOO~o~
It will be appreciated that this invention may be embodied in a two barrel carburetor by addition of another induction passage, main fuel passage, main metering orifice and rod, metering rod guide, idle fuel passa~e, mixture needle, and lower idle air bleed section, duplication of the bracket, solenoid, air bleed body and valve, and rich and lean stops i8 not required.
~S) Coil 380 i8 deenergized (~% duty J
cycle), throttle 316 i8 closed to the curb idle position, and air bleed bcdy 352 is turned on its threaded shank 418 to adjust the position of body 352 relative to bleed valve 364 and thus set the rich idle authority for carburetor 310.
(6) One or more of the foregoing steps is repeated, other flow points are checked, and pluqs 422, 424, 426 and 428 are installed to seal access to adjustable rich and lean stops 374 and 404, air bleed body 352 and mixture needle 334.
Thereafter the carburetor metering apparatus will meter fuel flow between the rich authority and the lean author-10'~ ;'7 ity when coil 380 is operated at any duty cycle pulse width between 0~ and lOO~o~
It will be appreciated that this invention may be embodied in a two barrel carburetor by addition of another induction passage, main fuel passage, main metering orifice and rod, metering rod guide, idle fuel passa~e, mixture needle, and lower idle air bleed section, duplication of the bracket, solenoid, air bleed body and valve, and rich and lean stops i8 not required.
Claims (2)
1. A carburetor comprising a fuel bowl section including main and idle fuel passages, a metering orifice in said main fuel passage, a metering apparatus vertically reciprocable between a rich position and a lean position, said apparatus including a bracket and a metering element operated by said bracket to restrict fuel flow through said orifice in said lean position and to permit increased fuel flow through said orifice in said rich position, an air horn section including an air bleed having a metering area above said bracket and opening into said idle fuel passage, said metering apparatus further including a bleed valve operated by said bracket to restrict air flow through said area and thereby permit increased fuel flow through said idle fuel passage in said rich position and to permit increased air flow through said area and thereby restrict fuel flow through said idle fuel passage in said lean position, said bleed valve having a tail which floats on and is biased into engagement with said bracket for operating said bleed valve whereby said metering orifice in said fuel bowl section need not be precisely aligned with said metering area in said air horn section to allow a common actuating member to operate both said metering element and said bleed valve, and said apparatus also including an actuating member for moving said apparatus between said rich position and said lean position to thereby effect control of fuel flow through both said main fuel passage and said idle fuel passage.
2. A carburetor comprising a fuel bowl section including main and idle fuel passages, a metering orifice in said main fuel passage, a metering apparatus vertically recipro-cable between a rich position and a lean position, said apparatus including a bracket and a metering element operated by said bracket to restrict fuel flow through said orifice in said lean position and to permit increased fuel flow through said orifice in said rich position, an air horn section including an air bleed having a metering area above said bracket and opening into said idle fuel passage, said metering apparatus further including a bleed valve operated by said bracket to restrict air flow through said area and thereby permit increased fuel flow through said idle fuel passage in said rich position and to permit increased air flow through said area and thereby restrict fuel flow through said idle fuel passage in said lean position, said bleed valve having a tail which floats on and is biased into engagement with said bracket for operating said bleed valve whereby said metering orifice in said fuel bowl section need not be precisely aligned with said air bleed body in said air horn section to allow a common actuating member to operate both said metering element and said bleed valve, and said metering apparatus also including an actuating member for moving said apparatus between said rich position and said lean position to thereby effect control of fuel flow through both said main fuel passage and said idle fuel passage, and wherein an air bleed body defines said area, said body including means for adjusting the position of said area relative to said bleed valve to thereby establish the proper air flow through said bleed and thus the proper fuel flow through said idle fuel passage.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US80106177A | 1977-05-27 | 1977-05-27 | |
| US801,061 | 1977-05-27 | ||
| US86871278A | 1978-01-11 | 1978-01-11 | |
| US868,712 | 1978-01-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1090667A true CA1090667A (en) | 1980-12-02 |
Family
ID=27122285
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA302,691A Expired CA1090667A (en) | 1977-05-27 | 1978-05-05 | Carburetor |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS53148627A (en) |
| AU (1) | AU527123B2 (en) |
| CA (1) | CA1090667A (en) |
| DE (1) | DE2821920A1 (en) |
| FR (1) | FR2392242A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2012369B (en) * | 1978-01-11 | 1982-05-12 | Gen Motors Corp | Carburettor and method of calibration |
| 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 |
| JPS56124699A (en) * | 1980-03-05 | 1981-09-30 | Hitachi Ltd | Self-suction pump |
| JPS57203850A (en) * | 1981-06-09 | 1982-12-14 | Hitachi Ltd | Air-fuel ratio controlling electromagnetic valve for electronic control carburettor |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5227772B2 (en) * | 1972-11-27 | 1977-07-22 | ||
| US3899551A (en) * | 1973-02-09 | 1975-08-12 | Acf Ind Inc | Apparatus for controlling and modulating engine functions |
| JPS5246578B2 (en) * | 1973-05-17 | 1977-11-25 | ||
| US3852383A (en) * | 1973-08-06 | 1974-12-03 | Gen Motors Corp | Part throttle adjustment |
| JPS5154132A (en) * | 1974-11-08 | 1976-05-13 | Nissan Motor | Nainenkikanno nenryoseigyosochi |
| FR2303166A1 (en) * | 1975-03-07 | 1976-10-01 | Sibe | IMPROVEMENTS TO CARBURATION DEVICES EQUIPPED WITH A CORRECTIVE CAPSULE, FOR INTERNAL COMBUSTION ENGINES |
| US4053543A (en) * | 1975-10-31 | 1977-10-11 | Acf Industries, Inc. | Air bleed control for carburetor idle system |
-
1978
- 1978-05-05 CA CA302,691A patent/CA1090667A/en not_active Expired
- 1978-05-17 AU AU36173/78A patent/AU527123B2/en not_active Expired
- 1978-05-18 DE DE19782821920 patent/DE2821920A1/en not_active Withdrawn
- 1978-05-27 JP JP6286978A patent/JPS53148627A/en active Granted
- 1978-05-29 FR FR7815928A patent/FR2392242A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2392242B1 (en) | 1985-04-26 |
| JPS6224624B2 (en) | 1987-05-29 |
| DE2821920A1 (en) | 1978-11-30 |
| JPS53148627A (en) | 1978-12-25 |
| FR2392242A1 (en) | 1978-12-22 |
| AU527123B2 (en) | 1983-02-17 |
| AU3617378A (en) | 1979-11-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |