US2984465A

US2984465A - Carburetor for internal combustion engines

Info

Publication number: US2984465A
Application number: US816420A
Authority: US
Inventors: Harry I Hazzard
Original assignee: Mcculloch Corp
Current assignee: Mcculloch Corp
Priority date: 1959-05-28
Filing date: 1959-05-28
Publication date: 1961-05-16
Anticipated expiration: 1978-05-16

Description

y 15, 1951 H. 1. HAZZARD 2,984,465

CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed May 28, 1959 2 Sheets-Sheet 1 4 /2/ a h i 5 -A I /27 I (I; l I F u; I24 [W| 92 0 62 0 9 93 9 O HARRY 1. HAZZAAD, y INVENTOR. WHA/VN a McMAN/GAL /4 a 36 Affomeys Fai- A J/Ean/ /70 bfgw M-Kk. 2 024 742;

H. l. HAZZARD CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed May 28, 1959 May 16, 1961 2 Sheets-Sheet 2 M m w H 1 M m H IN VEN TOR. WHANN & McMA/V/GAL Alf/army: for A i/mfi/ d/ hum nc-70? I CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed May 28, 1959, Ser. No. 816,420

12 Claims. (Cl. 26137) This invention relates generally to fuel supply means and relates more particularly to charge forming devices or carburetors for supplying and controlling the delivery .of fuel and air mixtures to internal combustion engines.

While the invention has particular utility as a fuel supply means for internal combustion engines of the two cycle type which are used with chain saws, lawn mowers, outdoor types of marine engines and the like, and is shown and described in such connection, it is to be understood that its utility is not confined thereto.

Charge forming devices of the pressure type have been used on internal combustion engines used with chain saws and other types of equipment which at times necessitate extreme angular and/ or inverted positioning of the engines, but various difliculties have been encountered therewith.

One of these difliculties encountered in one type of such pressure carburetors is inconsistent metering of the fuel. For example, in one such carburetor, undesired air flow occurs through the main jet while the saw engine is idling. Under such operating conditions, fuel is drawn out through the idle system and the main fuel system is wide open so that air enters into the diaphragm chamber and builds up to the idle fuel outlet holes. Air and fuel both go through the orifice together and the system be comes unstable. Should the air flow in too easily, the idle system soon runs out of fuel. Also, when the engine using such a carburetor is idled in an inverted position,

the diaphragm cavity partially fills with air. Now, should the throttle be suddenly opened to finish a cut,

instead of delivering fuel, the main fuel system must first be cleared of all this air.

It is, therefore, an object of the present invention to provide a charge forming device or carburetor wherein this difliculty is overcome.

Another object of the invention is to provide a charge forming device or carburetor that is stable and consistent in operation.

It is a further object of the present invention to provide a charge forming device or carburetor wherein air is prevented from entering the diaphragm chamber. This is effected by using a powdered metal filter which has a great number of small passages therethrough. The passages are small enough so that they hold fuel by capillary action and thereare no open holes so that no air can flow through without considerable pressure. In service, no air goes through because the suction in the diaphragm chamber is only a fraction of that required to pull air through the seal. However, this capillary seal offers practically no resistance to the flow of liquid fuel as the latter can go through while leaving all the capillary passages full.

Another object of the invention is to provide a device of this character that will give proper control of the air and fuel mixtures over the full operating range.

Still another object of the invention is to provide a charge forming device or carburetor that will be stable United States Patent when the engine is operated at extreme angular and/or inverted position.

A still further object of the invention is to provide apparatus of this character which prevents an overly rich mixture at high air flows.

Another object of the invention is to provide a device of this character that is reliable and accurate in operation.

Still another object of the invention is to provide a device of this character that is relatively simple in construction.

A further object of the invention is to provide a device of this character that is relatively inexpensive to manufacture.

The characteristics and advantages of the invention are further sufficiently referred to in connection with the following detailed description of the accompanying drawings which represent certain embodiments. After considering this example, skilled persons will understand that many variations may be made without departing from the principles disclosed and I contemplate the employment of any structures, arrangements or modes of Referring to the drawings which are for illustrativepurposes only:

Fig. 1 is a top plan view of a charge forming device or carburetor embodying the present invention;

Fig. 2 is an elevational view of the device taken from the throttle lever side thereof;

Fig. 3 is a view taken from the discharge end;

Fig. 4 is a view taken on line 4-4 of Fig. 3;

Fig. 5 is a plan view of the fuel pump diaphragm;

Fig. 6 is a plan view of fuel pump gasket;

Fig. 7 is an enlarged plan view of the filter; and

Fig. 8 is a diagrammatic sectional view showing the fuel and air system.

Referring more particularly to the drawings, the fuel feed and charge forming apparatus herein shown and described is particularly adapted for use with an engine of the so-called two cycle type wherein pulsing pressures are available, although it is to be understood that this apparatus may be used with other types of internal combustion engines or in connection with other devices where pulsating pressures are available.

Referring more particularly to the drawings, the device includes a carburetor body, indicated generally at 10, having an induction passage therethrough which includes an air inlet portion 12 and a mixture outlet portion 14 with a venturi 16 interposed therebetween and connecting said passage portions. By having the diameter of the inlet portion 12 the same as that of the outlet portion 14, improved operation has been obtained. At the outlet end of the carburetor body there is a flange 18 which is adapted to be secured to a boss 20 of the inlet of the mechanism to which fuel mixture is supplied. As shown, the boss 20 is on the wall of the crank case 21 of an internal combustion engine of the two cycle type, the engine inlet being in said boss 20. A gasket 23 is disposed between the flange 18 and the adjacent side of the boss 20, there being annularly spaced openings in the flange and aligned openings in the boss for reception of bolts 22 whereby the device is secured to the engine with the induction passage connected to the engine inlet which communicates with the crank case of said engine. Means for controlling the flow of fluid through the induction passage comprises a throttle valve 25, shown as being of the butterfly type, which is mounted on the usual throttle shaft 26 journaled in bearings 27. One end of the bottle shaft extends outwardly of its journal and is provided with .portions about the notch received in the groove 30 and said clip is secured to a downward extension 32 of the adjacent journal by means of a screw 33 received in an 1openingprovided'therefor in said clip and in an aligned tapped opening in said extension 32. Thus, 'thethrottle shaftis-held against longitudinal-movement but is free to -'rotate in its journals or bearings '27. The outwardly extending portion of the shaft 26 having the groove 30 is provided at its outer end with athrottlelever 34 which is in the shape of a bell'cr-ank. Lever 34 has an opening at the junction of the

arms

35 and 36 thereof for recep tion ofa screw 37 which is screwed into an axially arranged tapped opening in the adjacent end of said shaft 26. The throttle lever 34 is secured to the shaft in the usual well-known manner whereby said lever has a fixed .predetermined position on said shaft relative -to the position of the throttle valve 25. Arm 35 of the throttle lever is provided with *an opening 37' for operablere'ception of an actuating rod or link =38. There is-an arm 39 on the body which -exte-nds outwardly substantially .parallel to the throttle shaft-and which-is provided with -'a tapped opening adjacent the end for reception of a screw 40 having an idle screw spring 41 between the head of said screw and said arm 39. The screw 40-is adapted to be turned toward and awayfrom the free end of the arm 35 of the throttle lever 34 to serve as a stop limiting closing movement of the throttle valve so that said valve may be adjusted in a cracked'position for idling. Arm 36 of the throttle lever 34 is adapted to engage the underside of the arm 39 to limit opening movement of said throttle valve so that the latter cannot be rotated beyond the fully openiposition. V

The lower or under side of the body 10, as thus shown in Fig. 8, is recessed to provide'a fuel chamber -45.

The idle fuel system includes a recess 46 connected with a pair of small po'rts 47-and 48 spaced longitudinally ,apart relative to the induction passage and disposed'closely adjacent to -but at opposite sides of the trailing edge of the throttle valve when said valve is in the closed or substantially closed position. There is also an-air inlet .passage 49 connecting the induction passage with said recess 46, the inlet end of said passage 49 being spaced upstream of the port 48 and connected into the venturi '16 downstream of the throat 50 thereof. There is an idle fuel connection between the chamber 45 and the recess 46, said connection including the passage 51 leading into the bore 52, the latter having an outlet orifice ''53 leading to the recess 46. The bore'52 has an outer endportion that is tapped for threadable reception of 'the externally threaded body ofa needlevalve, indicated generally at 55. The'valve includes a reduced diameter stem extending axially from the'body 54 and terminating at its free end in a conical point "57 which'is adapted to adjustably control theeffective size of the metering orifice 53. 'The outer end of'said body 54 is provided with'a slot '58 for reception of a screw driver or othertool'for turning 'or adjusting said'valve. The inner end of'the recess 46 is closedby a press fitted disc 59 secured in the enlarged inner end portion of said recess 46.

The main fuel system includes a chamber or recess 60 closed at its inner end by a disc 61 press fitted into an enlarged portion at the inner end -of said chamber 60. At the opposite end of said'charnber 60 there is a flow selector device 62, described more particularly hereinafter, and at the outer'sideof'said device there is a "chamber 63 having a fuel'discharge passage 64 leading iaeiwtes and terminating in a conical free end 76 which is adapted to be moved inwardly and outwardly of the orifice 70 by turning the body 74 to vary the effective size of said orifice, there being a slot 78 in the outer end of said body for reception of a screw driver or other suitable actuating tool.

The recess 45 is closed by a flexible diaphragm 80 which has its marginal edge portion clamped between the body 10 and diaphragm plate 81. The side of the diaphragm plate 81 facing the diaphragm 80 is provided with a recess 82 of substantially the same diameter as the recess 45 at the diaphragm end thereof, said recess 82 serving as an air pressure balancing chamber which is connected by an air pressure balancing line 84 with the air inlet portion 12 of the induction'passage adjacent the inlet end of said portion 12.

At the lower end of the diaphragm plate 81 there is a :pressure pulsation chamber which is open at thelowe'r end of said diaphragm plate. said chamber 90 and disposed between said diaphragm .plate 81 anda fuel pump body 91 is a flexible-fueltpump Closing the lower end :of

diaphragm 92 which is marginally clamped'betweenlsaid diaphragm plate '81 and fuelpump body 91. Theapa'rts are secured together by any suitable means :such-as -.the bolts or screws 93, Figs. 2 and 3.

The pulsation chamber 90 is connected withfltlrecngifle crankcase by means of a passageway 94 which extends in the diaphragm plate 81, throughthe diaphragm 82"at a position outwardly of the chamber 82, and body -10. -.The passageway 94 terminates at a'port 95 which communicates with the crankcase in the well-known manner through a passage 96 in the boss 20. t

The fuel pump body 91 is provided in its upper side, as viewed in Fig.8, with a fuel chamber 100. Fuelzfrom any suitable source is conducted to :2. fuel inlet elfll in-m stem 102 of said body. The inlet 101 is connected-wither out portion in which is left a tongue 111. The tongue serves as a check valve member which is operable within the chamber 106 and is adapted to permitflowof ful from the chamber 102 to the chamber 101 zbut which prevents counter-flow of fuel. The recess 106 has an inclined part 112 which limits opening movement some tongue 111, said tongue being adapted toseat on' the upper surface area of the body 91 abouttheportTlfli-ihe bottom or open end of the recess 106 beingof sufficient size to permit such engagement of the tongue with the-iarea about the port 105.

The chamber-100 is connected with the chamber 45' by means of a-passage 115 in the body 91, apassage 116ain the d1aphragm plate 81 and a passage 117 in the body 10, there being an opening provided in the diaphragm ="80 providing port means betweenadjacent ends of the:-paS- sages 116 and'117. Passage 117 includes-an 'enlarge'd downwardly inclined portion in which is fitted securely a tubular member 118 which serves as-a-va'lveseatj-there being a filter 119 at the outer end. Cooperating with the seat 118 is a ball valve 120. An ifilet-controllever 121 is disposed in the chamber 45 and has a centrah su'bstantially horizontal part 122 with laterally extending parts substantially midway between the ends, said-pans being turned to form bearings 123 for reception-of a pivotpin 124 on which said lever. pivots. Thev pin -124 is disposed in a recess 125 provided therefor in :t-hebody 10, said recess 125 opening into the recess 45. Bin 124 is secured in position in the recess 125 bythehead ota screw'127 which is screwed into a tapped openingp rovided therefor alongside said pin 124. The head of said screw is disposed in an enlargement 128 of the recess 125.

It is to be noted that the lever 121 is disposed within a recess 130 provided therefor, the latter being open to the chamber 45. One end of lever 121 is inclined outwardly and downwardly, as at 131 to engage the ball 120. The other end of lever 121 has a downwardly and oppositely inclined portion 132 which terminates in an end portion 133 substantially parallel to the diaphragm .80 and resting on a plate 134 secured to the central area of said diaphragm 80. Plate 134 is attached to the diaphragm 80 by any suitable means such as an adhesive of well-known character and serves to reinforce the central area of the diaphragm as well as provide a bearing surface for the end portion 133 of lever 121. Lever 121 is yieldingly urged, by a spring 136, in a direction to urge the ball valve member 120 against its seat, said spring being operably disposed in a recess 137 provided therefor in the body and forming a part of the chamber 45. The lower end of the passage 116 is enlarged, as at 138, for operable reception of a tongue 140 which is left by cutting and opening 141 in a portion of the diaphragm 92, said tongue 140. serving as a check valve to permit fuel to flow from the chamber 100 to the chamber 45 but which will prevent reverse flow of said fuel. The inner side of the enlarged part 138 is provided with an inclined upper surface 142 which serves as a stop for opening movement of the tongue 140.

The operation of the fuel pumping mechanism is wellknown, the chamber 90 being connected to the crankcase of the two cycle type engine wherein the crankcase pressure alternately increases and decreases during each revolution of the crankshaft. Corresponding fluctuations of pressure occur in chamber 90 to actuate the diaphragm 92. When the pressure in chamber 90 decreases below atmospheric pressure, the diaphragm 92 is drawn upwardly to draw fuel into the chamber 100 from the source of fuel. When the pressure in chamber 90 increases the diaphragm 92 is forced downwardly to force fuel from the chamber 100 into the chamber 45, provided the valve 120 is unseated. This will occur when of the discharge or delivery of fuel from said chamber into the induction passage, either through the idling system or through the main fuel system. Such reduction in pressure in chamber 45 causes the diaphragm 80 to move upwardly and actuate the lever 121 so that valve 120 may move off its seat. When suflicient fuel has been pumped into the chamber 45 from the chamber 191), the pressure of fuel in the chamber 45 forces the diaphragm 80 downwardly and spring 136 actuates the lever 121 in the counterclockwise direction to effect closing or seating of the valve member 120.

When the engine is idling the throttle valve 25 is slight- 1y cracked and a fuel and air emulsion is discharged from the idle discharge port 47. Air for this emulsion enters the chamber 46 through the port 48 and the passage 49. As viewed in Fig. 8 the throttle valve 25 is opened by rotating same in the counterclockwise direction and should said throttle valve be opened sufliciently so that the trailing edge thereof will pass the port 48 so that the latter is downstream of said throttle valve, air for the air fuel mixture for idling is admitted into the chamber 46 through the passage 49 only and the idle fuel mixture is then discharged through the port 43 as well as port 47.

Heretofore, during the idling operation, the main fuel jet 64 does not discharge fuel, and air from the induction passage entered the fuel system through the jet 64. When this air builds up to the idle fuel outlet holes, the idling system becomes unstable.

The present invention overcomes this dilficulty and solves the problem of unstable operation from this cause by means of the capillary flow selector device 62 which is disposed in the fuel circuit between the chamber 45, and the discharge iet 64.

The device 62 is formed of powdered metal which is sintered and which has a multitude of small capillary passages which hold fuel by capillary action. As fuel fills these holes no air can flow through without considerable pressure and in service no air gets through because the suction in the chamber 45 is only a fraction of that required to pull air through the capillary passages of said flow selector device. However, this device offers practically no resistance to flow of liquid fuel as it can go through said capillary passages leaving all said passages full of the liquid fuel. Thus, undesired air is kept out of the fuel passages.

Other type of flow selector means may be used, such as, for example, a 200 mesh screen which will hold air pressure of 2.1" of fuel and which is adequate for the purpose. If greater pressure is to be held, then smaller holes are used. The surface tension of the fuel, and the wetability of the screen surface might be increased if necessary. The screen may be of any suitable metal or the like, one satisfactory metal is Monel.

Further opening of the throttle valve will cause a fuel to be discharged from the main metering jet 65, the metering jets for idling and above idling operation are so arranged and calibrated that there is a smooth transition in the supply of the proper fuel mixture for idling and above idling operation as the throttle valve 25 is opened.

Means for providing a suitably rich mixture for cold starting and warm up is provided and one such means comprises a butterfly type of choke valve 150 which is mounted on a shaft 152, said choke valve being disposed in the air inlet portion 12 of the induction passage and being of the same diameter as the throttle valve 25. Any suitable well-known means may be used for rotating the shaft 152 so that the choke valve 150 will be moved to a closed or open or intermediate position.

Fig. 5 illustrates the diaphragm 92 as it is actually constructed. The cutout portion serves as a passage leading from the chamber 106 to the chamber 100. In other words, the cutaway portion 110 serves the same purpose as the diagrammatically shown passage 107 in Fig. 8.

The cutaway portion 141 serves as a fluid connection between the chamber 138 and the passage 116.

The fuel pump gasket, indicated generally at 155, is disposed on the diaphragm 92, as best shown in Figs. 2 and 3. This gasket has

cutaway portions

156 and 157 which cooperate with the respective openings 110 and 141 to provide fuel flow passages for the purpose stated above in connection with said openings 119 and 141. Edge 158 of the opening 156 extends across the base of the tongue or valve member 111 so that said tongue flexes at this edge as it opens and closes the port 105. The opening 157 has a corresponding edge 159 which extends along the base of the tongue so that said tongue will flex at this line when opening and controlling the passage 115.

In Fig. 9 there is shown an alternative choke valve arrangement which comprises a choke valve, indicated generally at 160, and includes a cup-shaped member 161 with the open end facing the air inlet of the carburetor or charge forming device. At the closed end of the cupshape member 161, there is a collar 162 which is of smaller diameter than the diameter of the member 161 and from said collar there extends axially a stem 163 which is slidably disposed in a bore 164 provided therefor in a boss 165 of a wall 166 of housing 167. The wall 166 is in spaced and fixed relationship to the carburetor and the cup-shape member 161 is urged away from the air inlet of the carburetor by a spring 168 which has one end disposed in said cup-shape member 161 and the other end disposed in the air inlet portion 12 of the carburetor. When it is desired to provide an enriched mixture for a cld start or the like, the free end -'of the stem 163 'is pushed inwardly so that the cup-shape member 16 1 closes the air inlet of the carburetor or partiallycloses same as may be desired. When the engine has been started, the choke may be released so that the spring "168 'will 'movesame to the open position-as shown in Fig. 9, the shoulder 170 at the junction of the collar 1'62 and stem '163 then abutting against the inner face of'thewall 166 to serve as a stop limiting'opening movement of said choke.

It is thought that the invention and "manyof its attendant advantages will be understood :from 'the foregoing description and it is believed that'it will be apparent that various changes may be made in the iform, construction and arrangement of 'the parts of the in- "vention without departing from the spirit and scope thereof or sacrificing all of 'its material advantages, the embodiments hereinbefore described 'being merely preferred ones.

Iclaim:

-l. A charge forming device 'of'the character disclosed, in combination: a body formed with an induction passage including a venturi, and a fuel chamber; aflexible diaphragm forming a wall of said fuel chamber;.means for securing the diaphragm to the body, said means comprising a plate having a balancing chamber in the side adjacent said diaphragm, said balancing chamber being *connected with the induction passage at the inlet end thereof; a throttle shaft journaled in said body and operably positioned adjacent the downstream end of said venturi; a butterfly throttle valve disc secured to said throttle shaft; an idle fuel system including an idling fuel passage; a pair of orifices connected with the idling -fuel passage and spaced apartlongitudinally relative to the induction passage, said orifices being positioned adjacent the trailing edge of the throttle valve when the latter is closed and at opposite sides thereof; and air bleed connecting the induction passage with the idling 'fuel chamber and having an inlet spaced longitudinally upstream of said orifices; a main fuel system including "a main fuel passageway with an enlarged section adjacent the end thereof; a main fuel jet discharging adjacent the throat of the venturi and connected to said enlarged passageway section; a flow selector device at the entrance to said enlarged section of the main fuel passage, said device having minute capillary openings theret'hrough; a fuel inlet for the first mentioned chamber; a tubular valve seat secured in said inlet; a movable valve member cooperable with said seat for controlling the inflow of fuel to the first mentioned chamber; means for controlling said valve member comprising an inlet control lever having one end engaging said valve member; a pivot pin secured in a recess provided therefor in the top of the first mentioned fuel chamber; bearing means formed by portions of said lever intermediate the ends thereof and operably disposed on said pivot pin; a plate secured to the diaphragm at the fuel chamber side thereof, the opposite end of said lever having a partengaging said plate; a spring acting on said lever to urge same in the inlet valve closing direction; a choke valve shaft journaled in said body and extending diametrically of the induction passage adjacent the inlet end thereof and in parallel relationship to the throttle shaft; and a butterfly choke "valve disc attached to said choke valve shaft.

'2. A charge forming device of the character disclosed, in combination: a body formed'with a normally horizontal induction passage includinga venturi,.and a fuel chamber; a flexible diaphragm forming a wall of said fuel chamber; means securing said diaphragm to said body; a plate secured to the central portion of said diaphragm; a throttle shaft journaled insaid body opera- *bly positioned adjacent the downstream vend of said venturi; a butterfly throttle valve disc secured to .said throttle shaft; an idle fuel system including an idling fuel chamber; a' pair of orifices connected with the idling fuel chamber and spaced apart longitudinally --relative-to the induction passage, said orifices being positioned adjacent the trailing edge of the throttle valve when the latter is closed and at opposite sides thereof; an air bleed connecting the induction passage with the idling fuel chamber and having an inlet spaced longitudinally upstream of said orifices; a main fuel system including-a main fuel passageway with an enlarged section adjacent the end thereof; a main fuel jet discharging adjacent the throat of the venturi and connected to said enlarged section; a fluid flow selector device at the entrance to said enlarged section of the main fuel passage, said'device having minute capillary openings therethrough; a fuel inlet for the first mentioned chamber; a fuel inlet valve including a-valve seat and a movable ball valve member cooperable with said seat; a pivot pin secure'din the top of the first mentioned chamber; an inlet control lever pivotally mounted on said pivot pin having one end-engaging said ball valve member, the opposite end of said lever engaging said plate; and a spring acting on said lever to urge same in the inlet valve closing direction; a choke valve shaft journaled in said body and extending diametrically of the induction passage adjacent the inlet ends thereof and in'parallel relationship to the throttle shaft; and a butterfly choke valve disc attached to said choke valve shaft, said choke valve disc being of the same diameter as the throttle valve.

3. In a charge forming device of the rcharacter.dis closed: a body formed with a normally horizontal induction passage and .a fuel chamber; a flexible diaphragm forming a wall of said fuel chamber; means securing said diaphragm to said body; a plate secured to the central portion of said diaphragm; a throttle shaft journaled in said body and operably positione'dadjacent the downstream end of said venturi; a butterfly throttle valve disc secured to said throttle shaft; an idle'fuel system including a plurality of orifices connected with said fuel chamber and spaced apart longitudinally relative to the induction passage, said orifices being positioned adjacent the trailing edge of the throttle .valve when the latter is closed and at opposite sides thereof; a main fuel system including a main fuel orifice discharging into the induction passage anterior to-thethrottle valve; a main fuel passageway from said fuel chamber to said mainfuel orifice; a fluid flow selector device in said main fuel passageway, said device having 1minute capillary openings therethrough; a fuel inlet for said fuel chamber; a fuel inlet valve including a valve seat and a movable ball valve member cooperable Withsaid seat; an inlet control lever pivotally mounted .in said fuel chamber, said lever having one-end engaging said ball valve member, the opposite end of said lever engaging said plate; a spring acting on saidrlever to urge same in the inlet valve closing direction; and .a choke valve controlling the air-inlet of said induction passage.

4. In a charge forming device of the character disclosed: a body formed with a normally horizontalrinduction passage and a fuel chamber; a flexible diaphragm forming a wall of said fuel chamber; means securing said diaphragm to said body; a plate secured to the central portion of said diaphragm; a throttle shaft journaled in said body and operably positioned adjacent the downstream end of said venturi; a butterfly throttle valve disc secured to said throttle shaft; an idle fuel system-includ ing a plurality of orifices connected with said fuel chamber and spaced apart longitudinally relative to the induction passage, said orifices being positioned adjacent the trailing edge of the throttle valve when the latter is closed and at opposite sides thereof; a main fuel system'ineluding a main fuel orifice discharging into the induction passage anterior to the throttle valve; a main fuel passageway from said fuel chamber to said main fuel orifice;

a flow selector device in said main fuel passageway, said device having minute capillary openings therethroughpa fuel inlet for said fuel chamber; a fuel inlet valve ineluding a valve seat and a movable ball valve member cooperable with said seat; an inlet control lever pivotally mounted in said fuel chamber, said lever having one end engaging said ball valve member, the opposite end of said lever engaging said plate; a spring acting on said lever to urge same in the inlet valve closing direction; and choke means including a cup-shaped member aligned with said induction passage, the open end of said member facing the air inlet of said passage; a spring having end portions received respectively in the air inlet end portion of the induction passage and said cup and urging said cup away from the inlet end of said induction passage; a longitudinally extending part carrying said cup; and means slidably mounting said longitudinally extending part so that the cup may be moved to close said air inlet.

5. In charge forming device of the character disclosed: a body formed with an induction passage, and a fuel chamber; a flexible diaphragm forming a wall of said fuel chamber; means securing said diaphragm to said body; a throttle valve operably mounted in said induction passage adjacent to the outlet end thereof; an idle fuel system including fuel discharge orifices connected with said fuel chamber and adapted to discharge idling fuel adjacent one edge of the throttle valve when the latter is in idling position; a main fuel system including a main fuel passageway terminating in a main fuel jet discharging into said induction passage; flow selector means in said main fuel passageway, said means having minute capillary openings therethrough; a fuel inlet for said fuel chamber; a fuel inlet valve; and means connecting said diaphragm with said inlet valve whereby said diaphragm controls said inlet valve.

6. In a charge forming device: a body formed with an induction passage; means defining a fuel chamber, said means including a flexible diaphragm forming a wall of said fuel chamber; a throttle valve operably mounted in said induction passage; an idle fuel system having orifice means discharging into said induction passage, said orifice means being connected with said fuel chambers; a main fuel system including a fuel passageway connected with said fuel chamber and having a main fuel jet discharging into said induction passage; capillary flow selector means in said main fuel passageway, said means being formed of sintered, powdered metal and having minute capillary openings through which liquid will pass but which, when the differential of pressure thereacross is below a predetermined value, will hold back air when said openings have fuel therein; a fuel inlet for said fuel chamber; and a fuel inlet valve controlled by said diaphragm.

7. In a charge forming device: a body having an induction passage therein; means defining a fuel chamber, said means including a flexible diaphragm forming a wall of said fuel chamber; a throttle valve operably mounted in said induction passage; means for discharging fuel into said induction passage; and choke valve means comprising an elongated member at the inlet end of said induction passage; means slidably supporting said elongated member; a part carried by said elongated member at the end thereof adjacent the induction passage air inlet and movable into closing position relative to said air inlet when said elongated member is slidably moved toward said air inlet; and yielding means urging said slidable member in the opposite direction.

8. In a charge forming device: a body formed with an induction passage; means defining a fuel chamber, said means including a flexible diaphragm forming one wall of said fuel chamber; a throttle valve operably mounted in said induction passage; an air bled idle fuel system having means for discharging an idle fuel and air mixture into the induction passage, said idle fuel system being connected with the fuel chamber; a main fuel system including a fuel passageway connected with said fuel chamber and having a main fuel discharge jet for discharging fuel into said induction passage; a capillary flow selector disc in said main fuel passageway; and fuel inlet means for the fuel chamber, said fuel inlet means being controlled by said diaphragm.

9. In a charge forming device: means defining an induction passage; means defining a fuel chamber, said means including a movable wall; a throttle val ve operably mounted in said induction passage; an air bled idle fuel system having fuel discharge orifices connected with the fuel chamber; a main fuel system including a passageway connected with said fuel chamber and having a main fuel discharge orifice for discharging fuel into said induction passage; a capillary flow selector disc in said fuel passageway; and fuel inlet means for said fuel chamber, said fuel inlet means being controlled by said movable wall.

10. In a charge forming device: means defining an induction passage; means defining a fuel chamber, said means including a movable wall; a throttle valve operably mounted in said induction passage; an idle fuel system including means for discharging idling fuel into the induction passage, said idle fuel system being connected with the fuel chamber and having fuel discharge orifice means and an air bleed connecting the induction passage with the idle fuel system; a main fuel system discharging into the induction passage and having a connection with said fuel chamber; capillary flow selector means in said main fuel passageway; and fuel inlet means for the fuel chamber, said fuel inlet means being controlled by said diaphragm.

11. In a charge forming device: means defining an induction passage; means defining a fuel chamber; a throttle valve operably mounted in said induction passage; an idle fuel system discharging idling fuel into the induction passage; a main fuel system connected with said fuel chamber and discharging fuel into the induction passage; and flow selector means in said main fuel system, said selector means being formed of sintered, powdered metal and having minute capillary openings through which liquid will pass but which, when the differential of pressure thereacross is below a predetermined value, will hold back air when said openings have fuel therein.

12. In a charge forming device: means defining an induction passage having an air inlet and a mixture out let; a throttle valve operably mounted in the induc tion passage; an idling fuel system for discharging idling fuel into the induction passage; a main fuel system for discharging a main fuel supply into the induction passage; and choke valve means including a plunger-like member in alignment with the induction passage and having an end portion adapted to close the air inlet of the induction passage; means slidably supporting said plunger-like member whereby, with sliding movement thereof toward the induction passage, said end portions will be moved toward the air inlet; and means yieldably urging said plunger-like member away from said induction passage.

Bracke Apr. 6, 1954 Phillips July 1, 1958