US1913741A - Charge forming device - Google Patents

Description

June 13, 1933 F. E. AsELTlNE E1' AL 1,913,741

CHARGE FORMING DEVICE Filed June 12, 1929 5 Shets-Sheet l Swix/tou fred I dseltzne [l/z'lfard M Jester June 13, 1933.

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Jmmuou en' 6. danltina 'Wilford )Y Jester Carl A( jndl dnd frederic/(f D. fanaten Sa... an. 4l-5m 3y dA- .7i/eif- GMW June 13, 1933- F. E. AsELTlNE ET AL 1,913,741

CHARGE FORMING DEVICE Filed June 12, 1929 5 Sheets-Sheet 3 JUN 13, 1933- F. E. ASELTINE ET AL 1,913,741

CHARGE FORMING DEVICE Filed June 12, 1929 5 Sheets-Sheet 4 m ,n v. 'o 'P 'IQ Q 3 g a JMW .fred dseltins (llll'ard )Y Jeter Carl Jrf /YzndL arid .frederic/h fana-fan June 13, 1933.- F. E. AsELTlNE Er AL CHARGE FORMING DEVICE Filed June l2, 1929 5 Sheets-Sheet 5 mwsg w luk #un 'gl/ll 'IIIIIIA YIIIIIII Patented June 13, 1,1933

` UNITED STATES FRED E. ASELTTNE, WILFORD H. TEETER, cam. n.

or DAYTON, OHIO, AssmNOns To DELOO rnODUcTs CORPORATION, OF DAYTON,

OHIO, A COIBPORATlON 0F DELAWARE lm'i'letla'l;y OFFICE FOBHING DEVICE Application. lcd .Tune 12, 14929. Serial Hb. 870,178.

This invention relates to charge fbi-ming devices for internal combustion engines, and most particularly to that type of charge forming device which comprises aplurality of primary carburetors, one for each intake port of the engine, Whicl are adapted to deliver a primary mixture of fuel and air to applurality of secondary carburetors located adjacent the engine intake ports where additional air is mixed with the primary mixture before the latterenters the engine cylinders.

An example of a charge formin device of this type is disclosed in the app ication of Fred E. Aseltine, Wilford H. Teeter andl Carl H. Kindl, Serial No. 288,683,'iled J une 27, 1928. l i

It is the general object of the present invention to provide an improved device of the character referred to, in which. the means for controlling the supply of air and fuel thereto are elfective to provide a mixture of the desired proportions to most satisfactorily operate the engine under all possible operating conditions.

With this general object in view, one feature of the invention consists in the provision of means for controlling the fuel supplyV which includes'fuel Vsupply chambers communicating with the primary carburetors and to which the fuel jets deliver fuel, in combination with means for maintaining in said chambers a suction which is substantially that determined by a suction operated air valve, which controls the admission of air to the device.

^ A further feature of the present invention resides in the provision of primary mixture conduits lying between the primary carburetors and the secondary carburetors, which comprise alternately arranged round and Hat sections. l

A still further feature of the invention consists of a manifold in which the primary mixture conduits are formed during the casting of the manifold. i p y Another feature of the invention comprises improved means :for controlling the operation of an auxiliary air valve which regulates the supply of airv to the secondary carburetors, said means comprising a dashpot and an auxilialy piston controllingV its operation, which 1s a apted to be restored toits original posi- I-INDL. AND FREDERICK D. FUNSTON,

tion after each movement of the air valve,

so as to retard the opening of said air valve to the same 4degree regardless of the position of the valve at the beginning of its opening movement.

Anotherfeature of the invention is improved means for enriching the mixture on acceleration consisting of a pump operated on opemng movement of the throttle comprislng a piston which is adapted to be engaged by its operating means as the throttle is opened, ut is rovided with independent yielding means y which itfis returned to normal position, and a-,mell into which the pump delivers and in which atmospheric pressure is maintained at all times.

Another feature of the invention resides lin the provision of means for 'supplying additional fuel to1 the fuel 'ets which is manually controlled so as to operable to effect a seasonal adJustment or at any Vother time -it may be desired to supply an enriched mix- Fig. 1 is a plan view of a charge forming device embodying this invention, the manifold being broken. away in order to show the end portions thereof.

Fig 2 is a side elevation of the device shown in Fig 1 looking toward the engine.

Fig. 3 is a vertical section on the line 3-3 of Fig. 1.

Fig. 4 is a side elevation of the main carburetor unit viewed from'the left in Fig. 1, and having parts shown in section.

Fig. 5 is a side elevation of the main carburetor unit seen from the right in Fig. 1 and being partly broken away to show certain parts in section. v

Fig. 6 is a transverse, vertical section on the line of Fig. 3. p

Fig. 7 is a horizontal sect-ion on the line 7-7 of Fig. 3.

Figs. 8, 9, 10, 11, 12 and 13 are detail, fragmentary sections on the lilies 8 8, 9 9, i010, 1i 11,1212 and 1a 1a of Fig. 7.

Fig. 14 is a detail view of the throttle.

Fig. 15 is a fragmentary elevation of the dashpot casting seen from the right in Fig. 4.

Fig. 16 is a fragmentary section on the line lC-lti of Fig. 4.

Fig. 17 is a fragmentary section on the line 17-17 of Fig. 7.

Fig. 18 is a detail of a valve operating connection.

The device disclosed herein comprises a main air manifold 10, having three outlet branches 11. 12, and 13, each of vwhich is adapted to comnmnicate with o ne ofthe intake ports of a multicylinder engine. These branches are each provided with an attaching iange 14, which is adapted to be attached to the engine block in the usual way. Ad jacent Iits inlet, the manifold is provided with a flange. 15 to which the main carburetor unit, hereinafter described, is adapted to be secured, as shown in Fig. 3.

The main carburetor unit comprises the main housing 16 inthe form of a single casting having a flange 17 adapted to be secured by screws 18 to the flange 15. A valve controlled air inlet coupling 19 is secured in position over an opening in the top of the housing 16 by screws 20, as shown in Fig. 1, or in any other desirable manner. A casting 21 having a pump cylinder and certain dashpot chambers and fuel passages formed therein as hereinafter described, is secured by screws 22 to the bottom of the main housing, a suitable gasket being provided between the castings to prevent leakage. A sheet metal fuel bowl 23 is held tight against an annular surface 24 on the bottom of the main casting by a screw 25 screwed into the casting 21, a gasket 26- preventing leakage around the screw.

A fuel supply line leading from a main source of fuel supply is adapted to be connected with a passage 30, formed in a boss 31 projecting from the main housing. A plug 31a normally closes another bore in the casting which communicates with the passage 30 and in which the fuel line may be connected if desired. If so connected the plug 31a may be screwed into the boss 31. The passage 30 is of angular form and connects at its'inner end with a vertical bore 32 in the casting 21, a nipple 33 being screwed into the enlarged lower end of this bore, as indicated in Fig. 5. The passage through the nipple communi- Cates with the passage 32 and is restricted at 34 to form a valve seat with which a fuel Valve 35 cooperates. This valve .is of square cross section as shown in Fig. 5 so as to permit a flow of fuel past the valve when the latter is off its seat, and is controlled by a oat 36,

'secured to an arm 37, pivoted on a pin 38, supported by the casting 21 and a bracket 39 depending therefrom and integral therewith. The iioat vcontrols the valve 35 to maintain a substantially constant level of fuel within the float chamber 23 lin the'usual manner.

A plurality of angular primary mixture passages indicated by the reference character 40, and hereinafter more fully described, are formed in the lower part of the main housing 16. Communicating with the vertical portion of the mixture passages 40 by means of orifices 41, are three chambers 42, for convenience designated fuel supply chambers.

'lhe fuel is adlnitted directly to these cham` bers 42 by means hereinafter described, and is mixed therein with a small quantity of air admitted to said chambers by means of a slot 43 formed in a partition separating the fuel chambers from a main air chamber as later described. This mixture or emulsion of fuel and air flows to the primary mixture passages 40 from said chambers 42 as hereinafter set forth. Communicating with each of the fuel supply chambers 42, are two fuel inlets 44 and 45, which are rendered effective successively in a manner to be later described, and which constitute part throttle and open throttle metering orifices respectively. The inlet 45 is in the form of a nozzle projecting into the fuel supply chamber. Fuel is conducted from the ioat chamber to both of these inlets through a vertical passage 46 formed in the casting 21 and illustrated in detail in Figs. 8 and 9. 'lhis passage communicates at its upper end with a horizontal fuel canal 47, which in turn communicates with both of the above mentioned fuel inlets. Fuel is supplied to the passage 46 at all times through a fuel in the fuel reservoir 24. After a certain .predetermined throttle movement, a valve 49 normally held closed by a spring 49a, is opened by means to be later described, to permit fuel to flow from the reservoir 24 around said valve into a bore 50 in the casting 21, and thence through a horizontal passage 51 at the. bottom of said casting and a metering plug 52 at the bottom of the passage 46. Additional fuel is supplied by the above described passages to provide the necessary quantity of fuel when the engine is operating at relatively high speeds. A still further means for supplying additional fuel to the inlets 44 and 45 under certain conditions, comprises a fuel passage controlled by a valve 53, operated by means later described. This a calibrated plug 58 therein to regulate the quantity of fuel supplied thereby.

The inlet 44 is provided with 'a lv'estriction 60 to regulate the quantity of fuel flowing therethrough and the inlet has a similar restriction 61 therein to control the fuel flow therethrough. At very low speeds, the suction within the chambers 42 is insufficient to lift fuel from the top of the nozzles 45, which project into the chambers, but is enough to cause a flow from the nozzles 44, which will supply sullicient fuel to operate at such low speeds. At a predetermined speed, the suction eilective on the nozzles 45 becomes suiiicient to draw fuel therefrom and at all higher speeds, the nozzles 45 are eifetive to supply the major portion of the fuel consumed by the engine. The fuel supplied by the nozzles is mixed with air entering" through the orifice 43 and this mixture is drawn into the primary mixture passages through orifice 41, as previously setvforth. It is mixed with additional air therein and is conveyed by the primary inixture conduits, hereinafter described, to the secondary mixing chambers where, undercertain conditions, it is mixed with additional air to form a mixture of the desired proportions'to operate the engine under those operating conditions.

The primary mixture passages are'controlled by a single throttle valve 65, which extends across all of the passages and is provided with grooves 66, which are adapted to register with said passages. T he grooves 66 each merge into smaller grooves 67. which are adapted to provide a passage for the mixture `necessary to operatethe engine when idling,

said grooves 67 being open when the throttle `lis in closed position las indicated in Fig. 3. :The grooves 67 are provlded of as small size fas possible vso as to minimize dimensional errors between the'lndlvldual grooves, whereby the variation in area of opening between 'individual grooves will be as small-as possible.

All the fuel supplychambers 42 communicate with a chamber 69, which for convenience may be termeda primary air chamber. The chamber 69 and fuel supply chambers 42 are separated from the main air chamber 70, hereinafter described, by means of a single partition plate 71 and the chambers 42 are also separated from the vertical `portions of the primary mixture passages by means of avertical partition 72, whichis a part of the main casting on which the plate 71 is supported. Separating the chambers 42 from each other are partitions 73, which are also a part ofthe main casting 16.

All the air supplied to both the air chambers 69 and 70 is admitted through the coupling 19, and is controlled by means of a valve 75 normally held against its seat 76, by

means of a spring 77, which is received beftween the valve and a flange 78 projecting from a sleeve 79, slidably mounted on a guide sleeve 80, which is securedlby any desirable means in the main housing 16. Under `norlnal operating conditions the sleeve 79 occupies the position shown in Fig. 3', but may bevlifted from this position by means of the choke mechanism so as to hold the air valve 75 closed to facilitate starting.

The choke mechanism comprises a bell crank lever 81 pivoted on a pin 82, screwed into a boss 83 formed on the main housing, or secured in position in .any other desirable manner. A suitable operating connection, extending to a point convenient to the operator, may be connected to a pin 84, pivoted in L the upper end of said choke lever. The upper end of said lever is bent over las indicated Vin Fig. 5 and the two ends of the lever are held together by means of a screw 85. The inner surfaces of the two parts of the lever 81`are threaded and'eugaging therewith is a stop screw 86, which is adapted to engage the main housing to determine the normal position of the choke lever. By adjusting the screw to different positions, the normal pressure of the spring 77 on valve 75 may be regulated as desired. Onearm of the lever 81 extends through the wall of the main housing and is provided with aitoe 87, which lies beneath flange 7 8 and lifts the flange and sleeve 79 when the lever is rocked in a clockwise direction, as in Fig. 6, engaging the sleeve withvalve to hold the latter closed. When the air Valve is held closed, as described. suilicient air to carry the starting fuel vfrom the fuel supply chambers to the engine ports is admitted through air lchannels 88, formed in the upper surface of the'air valve 75. Also, if desired, the choke lever 81 may be provided with a flat surface 89 to admit air through the wall vof the main housing when the choke lever is in its operated position.

The valve 75 admits air directly to the main air chamber 70. which supplies air to the primary air chamber 69. through slot 43 as previously described. Air also fiows from the main air chamber to the secondary mixing chambersthrough a. main air conduit 90, con trolled by a manually operable valve 91, secured to a shaft 92, journalled in the main housing, and a suction operated valve 93, se-

cured to a shaft 94, which is also rotatably connect each passage 40 with the secondary air conduit 90, for a purpose to be later described.

It will be noted that the slot 43 which connects the main air chamber with theprimary air chamber (S9, is considerably larger than the total area of orifices 41, whichconnect the chambers v42 with the primary mixture passages. lIn view of this difference in area, it will be obvious that the lion." of air through the chamber ($9 and the chambers 42 communicating therewith must necessarily be at very low velocity. Because of the lowy velocity of the air passing the fuel inlets, there is substantially no velocity head created at said inlets under any operating condition or speed.

Airis admitted to the chamber 69 more rapid-` ly than it can be exhausted therefrom, hence there is substantially no difference in the pressure maintained on opposite sides of the plate 71, which divides the chambers 69 and 70. The suction at the fuel inlets therefore, is at all engine speeds substantially the static suetion of the air chamber as determined by the spring 77 which controls the opening ofthe main air valve.

The orifices 95 which connect the space in the passage 90 between the valves 91 and 93 with the three primary mixture 'passages are effective to communicate the suction of said primary mixture passages to said space and this suction will hold the valve 43 closed when the valve 91 is closed and until the pressure differential on opposite sides of the valve 93 in enough to overcome thel resistance ot' the dashpot normally retarding the opening of such Valve. These orifices therefore effect a slight delay in the opening of the valve 95S from its closed position, with respect to the opening of valve 91.

During operation at all engine speeds below a certain predetermined speed, for example, that corresponding to a Vehicular speed of 20 to 25 miles per hour on a level, the mixture supplied to the engine by the primary mixture passages is of properly combustible proportions and is conveyed to the engine without mixture with additional air in the secondary carburetors. At higher engine speeds than this, the valves controlling the fiow of air through the secondary air'passage are opened to supply additional air-and increase the quantity of mixture supplied theY engine.

The valve 91 is operated by means of the primary .throttle afterhsaid primary throttle has made a certain amount of independent movement subsequent to which movement thev valve 91 is movedsimul# taneously with the said primary throttle. To this end, the primary throttle is provided with an operating arm 100, secured to the end of the primary throttle by a screw 101, and having pins 102 thereon which are adapted to be held in engagement with corresponding recesses 102a in the end of the throttleA by said screw 101. The arm 100 is provided wit a hole 103 in its free end in which any suitable connection extending to a point convenient to the operator is adapted to be connected. Secured in position by the screw 101, is an arm 104 having its free end bentover, as'indicated in Fig. 1, and threaded between the two parts of said arm is a stop screw 105 adapted to engage a fixed stop 106, projecting from the main housing to limit the closing movement of the throttle. By adjusting thefscrew 105, the normal closed position of the throttle may be regulated as'desired to determine the idling speed of the engine. v

Secured to the other end of the primary throttle is an operating plate- 107, having pins 108 on its rear face engaging recesses in the throttle andI held injpos1tion against the end of said throttle by a screw 109, which is screwed into the end of the throttle and is provided with a shoulder 110, which engages a collar 110a lying between said shoulder and the plate 107, as shown in Fig. 16. Pivotally connected to an ear 111, projecting from the operating plate 107,-is a link 112, the upper end of which is provided with a short slot 113, in which is received a pin 114, projecting from an arm 115, secured to the end of the shaft 92, of the valve 9,1. A spring 116 engages the pin 114 at one end y and the other end thereof engages a lug 117, projecting from the link 112, said spring operating to hold the parts in such position that the pin 114 normally occupies the lower end of the slot 113. ranged that when the throttle is opened the point of connection of the link 112 with the plate 111 moves in a clockwise direction, as shown in Fig. 4, and during the first part of its movement, this point of connection moves inthe are of a circle, the center of which is' the pin 114, solthat While moving in this arc there is no tendency of said link to move the pin 114 and the valve 91. This movenient takes place during the first part of the opening movement of the primary throttle and after said throttle has moved through a predetermined distance, the point of connection of the link 112 and the plate 107 no longer moves in an arc concentric with the piri 114 but its movement is effective. to move said pin in a clockwise direction and thus move the valve 91 towards its open position. The slot 118 is provided to prevent binding of .theI partswhich might occur otherwise, but under normal conditions, the pin 114 is held y substantially in fixed position relative to the slot by means. of the spring 110. ClosingV or counterelockwise movement of the primary throttle and the plate 107 will obviously move the valve 91 to closed position.

The. valve 93 is adapted to be'opened entirely by engine suction, but until the valve The parts are so arl by means 'of a spring 120, one end of which is connected to an ear 121 projecting .from the member 118 while the other end is con- 10 nected to a pin 122 projectingfrom the castfuel from the Afuel reservoir by le ing 16. In order to close thel valve 93, an arm 123 is secured in any desirable manner to the valve shaft 94, and this arm is pivotally connected at its free end to a link 124 the other end of which is connected to a dashpot piston to control the opening movement of the valve 93, in a manner to be 'later described. The link 124 is received between the two arms of the bifurcated lever 118 and a pin 125, projecting from said link, is engaged by one arm of the member 118, when said member is moved in a counterclockwise direction to close the valve 93 and to hold such valve closed until the valve 91 isopened during the opening movement of the throttle. In order to permit the opening of the valve 93 by engine suctiolnit is obvious that the arm 118 must be moved out of engagement with the pin 125. This is accomplished by the throttle operating mechanism when the throttle is moved through a predetermined distance. For this purpose a pin- 126 is secured to the operating plate 107l and is adapted to engage one arm of the member 118, as said plate is moved in a clockwise direction, rocking the member 118 in a clockwise direction and moving said member out of engagement with the pin 125. As the valve 93 begins to open the suction effective to open said valve is sufficient to open it against the tension of spring 120 until a predetermined engine speed is reached, butat higher speeds the position to which the member 118 is moved, as above described, determines the amount of opening movement the valve 93 ,may make, the engine suction being then insuflicient to overcome the tension of the spring 120.

On opening movement of the throttleor the valve 91, the suction in the air chamber is increased and the main air valve 75 is opened against the pressure of its spring to permit an increased flow of air ast said valve. It has been found that durmg opening movements of said valve, it will flutter if allowed to open freely and in order topi-event liuttering, a, dashpot of conventional form is provided to control the motion of said valve. The dashpot consists of a cylinder 130 formed in the casting 21 and a' piston 131 secured in any desirable manner to the lower end of a stem 132 on which the valve 75 is mounted. This dnshpotis of ordinary construction and is .adapted to be filled with akage around the piston when the air valve is stationary, and through a hole 134 in the bottom of the cylinder, fuel esca ing slowly from the cylinder through said ole and by leakage around said piston during opening movement of the valve whereby such opening movement is stcadied.

In order to prevent a tendency of the air valve to enrich the mixture by gradually moving toward closed position because of the effect of engine pulsations at relatively low speeds the dashpot piston 131 is rovided with small holes 220 therethroug and a check valve, comprising a flanged sleeve 221 closes the ports on upward movementsof the air valve. The dashpot therefore resists closing movements of the valve to a greater degree than opening movements.

0n opening of the throttle, it has been found necessary to provide a somewhat enriched mixture in order to properly operate the engine during the acceleration period for reasons which are well known to those skilled in this art. For this purpose, the device disclosed herein is provided with a fuel pump operated bythe primary throttle and designed to temporarily supply additional fuel to the primary mixture passages in the man- A ner hereinafter described. It has also been found necessary, in order to secure the desired mixture enrichment, to provide means for retardin the opening of the valve 93 during opening movements of the main air throttle 91. This is necessary in order to produce a sufficient pressure dilerential between the inlet and outletends of the primary mixture conduits to create a velocity of flow through said conduits great enough to transport the enriched primary mixture from the fuel supplychambers 42 to the secondary mixing chambers, hereinafter described, almost instantaneously. It is a considerable distance from the fuel supply chambers to the secondar mixing chambers where the primary mlxture is mixed with air flowing through the auxiliary air passage and if the valve 93 were permitted to open freely, an appreciable time interval would be necessary for the rich and relatively heavy primary mixture to travel through this distance, obviously a greater time interval than that required for the pure air to travel from the air throttle 91 to said secondary mixing chambers. By retarding the opening of the valve 93, the time interval necessary for the primary mixture to reach the secondary mixing chambers is reduced, while that necessary for the air flowing past the valve- 91 is increased,

ferredto, is'pivotally connected at its lower end in any desirable manner to a dash ot piston 135, which is slidable in a cylin er 136, formed in the casting 21. A valve cage 137 having a passage 138 therethrough, is secured in a plate 139, secured to the bottom of the casting 21 by screws 140, so that the passage 138 w1ll admit fuel to the cylinder 136 from the fuel reservoir when a check valve 141, received in the valve cage, is unseated. Upward movement of the check valve is limited by a pin 142, positioned above the valve. It will be obvious that upward movement of the piston 135 is substantially unretarded as the check valve 141 is opened during such upward movement to permit the dashpot cylinder to be filled with fuel, but downward movement of the piston 135, which takes place on opening of the valve 93, is retarded to delay the opening of said valve.

In order to regulate the retarding effect of the above described dashpot so as to retard the opening of the valve to substantially the same extent at whatever position the valve may occupy when its opening movement begins, an auxiliary cylinder 143 is provided which is positioned in the casting 21 immediately adjacent the cylinder 136 and communicates therewith by the assage 144, at the bottom of said cylinder. gliding within the cylinder 143 is a piston 145, which is normally held in the position shown in Fig. 3 by a spring 146, received between the piston and the top of cylinder 143. On downward movement of the piston 135, the piston 145 is lifted, pressure being applied to the fuel beneath said iston by means of the dashpot piston. The uel above the piston 145 in the cylinder 143 is forced' out of such cylinder during its upward movement throu h a small hole 147 near the top of the cylin er, and the rate of escape of fuel through such orifice determines the retarding effect of the dashpot on the valve 93. After the valve 93 has completed any o ening movement, the spring 146 forces the piston 145 downwardly until it occupies the position it occupied at the beginning of the opening movement of the valve 93, and the cylinder 143 is filled with fuel from the fuel reservoir, which flows into such cylinder -through the orifice 147, above mentioned. It

should be clear, therefore, that the piston 145 occupies the same position whenever an opening movement of the valve 93 takes place, so that the retarding effect of the dashpot on the valve is substantially the same for every opening movement thereof.

According to this invention, the pump for supplying -additional fuel to the primary mixture passages is operated by the primary throttle during its opening movement. lThis pump comprises a cylinder 150, formed in the casting 21 and a piston 151 which is slidable therein. The piston 151 is operated by a rod 152, pivotally connected to the pin 126,

which projects from the operating plate 107. The rod is not actually connor-ted to the piston 151, but the lower cud of such rod is received inside of a tube 153, which is secured to the piston and projects upwardly therefrom. The normalposition of the rod 152 is such that the lower end of said rod is sulstantially in engagement with the piston 151, the piston heilig held in this position by a spring 154, which is received in the cylinder 150 below' the piston. Obviously, since any opening movement of the throttle is ell'ected by a clockwise movement of the operating plate 107, the rod 152 is moved dowuwaiwlly and moves the piston downwardly through a corresponding distance. On closing movements of the throttle, the piston is lifted by means of spring 154, as the rod 152 moved upward. The pump cylinder communicates with a fuel delivery conduit 155, which at its upper end communicates with a fuel well 156, formed in the casting 21. This well is o en to atmosphere by means of the orifice l5 which is of larger size than the fuel delivery conduit so that atmospheric pressure is maintained in the fuel well 156 at all times. A check valve 158 is provided in an enlargement 159, at the upper end of the fuel delivery conduit adjacent its point of connection with thewell 156,'to prevent fuel returning to the pump cylinder when the pump is stationary or during its upward movement'. The fuel flows from the well 156 to a chamber 160, formed in the casting 21 immediately adjacent the well, through three fuel passages 161. 'lhe chamber 160 is vented by means of the passage 162 which connects the top of said chamber 160 with `the atmosphere, as illustrated in Fig. 7. 'lhe chamber-160 is connected with three vertical passages 163 positioned relatively close together by means of three horizontal passages 164 at the bottom of the chamber 160. The two outlet passages 163 are connected at their upper ends with channels 165, formed in the upper surface of the casting 21 and these channels communicate at their outer ends with two outer vertical passages 166, formed in the main housing 16 and communicating with the two outer primary mixture passages 40, the middle passage 163 communicates directly with the middle passage 166, which connects with the middle primary mixture passage, as indicated in Figs. 3 and 7. The fuel flows from the well 156 to the chamber 161 by gravity and in such chamber is mixed with air supplied thereto through the passage 162, to form an emulsion of fuel and airwhich is drawn into the primary mixture passages through the various passages above described, by the suction maintained in said mixture passages. Air is admitted through the passage 162 so that the suction in the various fuel delivery passages between the check valve and the primary mixture passages is never sufficient todraw fuel from the pump cylinder to said mlxture passages, whereby fuel is only delivered on operation of the pump. Each of the vertical passages r valve to open it and permit a flow of fuel through the high speed inlet.

The manually operated valve 53 hereinbefore referred to, is provided primaril for the purpose of regulating the suppl o fuel in accordance with the seasons. f course a somewhat richer mixture is required during cold weather than is necessary during the summer months, and means are provided to open or close this valve as desired. This means comprises a cam 175 on the inner end of a short shaft 176, which is. rotatably mounted in the rear wall of the main housing, as shown in Figs. 2 and 3. An operating arm 177 is secured by a screw 178 to the outer end 0f the shaft 176 and a spring 179 is received on the shaft between the cam 175 and the casting 16 to prevent longitudinal motion of the shaft. The arm 177 is provided with an orifice 180 in which any suitable connection extending to the operator may be received. It is obvious that the cam 175 may be operated at any time to provide a somewhat richer mixture although, as above indicated, it is intended primarily as a seasonable adjustment.

The primary mixture passages 40 register with three primary mixture tubes 190, 191 and 192, as shown in Fig. 1. `These tubes are formed of sheet metal and comprise round sections indicated at 193 and relatively flat sections 194. These tubes are positioned in the intake manifold as indicated in Fig. 1, and terminate at one end at the fiange 15, Where the manifold is attached to the main carburetor unit and at the other end at a point adjacent the intake ports, such tubes extending centrally through the outlet branches 11, 12 and 13 of the manifold and being cast in position in said manifold during the casting i of the latter. .It will be observed that the round portions of the tubes 190 and 192 are situated at those points where these tubes are bent, while the round part of the tube 191 is adjacent its point of connection with its associated passage 40. The tubes are formed as illustrated for a plurality of reasons. First,

by making the tubes alternately round and flat, the cross sectional area of such tubes is varied throughout their length so that there is an alternate expansion and contraction of the mixture flowing therethrough, which tends to secure a more homogeneous mixture in which the fuel content is`more equally distributed than would be possible with tubes having the same area throughout their length. The flat sections of the-tubes also increase the velocity of flow therethrough because of a reduction in cross sectional area and since the bottom of said sections is nearly flat, the surface over which the fuel flows through the tubes is considerably increased so that there is a greater tendency to evaporation and less tendency for fuel to collect on the wall of the tube. Those tubes which are bent are left round at the points' where the bends are located in order to facilitate bending, and the ends of the tubes where they register with the passage 40 are also ro'und 1n order to coincide with the outlet ends of such assages.

The secondary mixing cham rs are located ad acent the outlet ends of the primary mixture tubes above described, and comprise means for straightenin and accelerating the flow of air past the en s of said tubes. This means comprises an inner tube 200 which is spaced from the rimary mixture tube and is secured by a spi er 201 to an outer tube 202, which is provided with an enlargement 203 forming a shoulder 204 where it joins with the smaller portion. When the device is assembled, this shoulder 204 isadapted to be held against a corresponding shoulder 205, formed in the outlet branch of the intake manifold and the other end of the enlarged 4portion 202 engages a similar shoulder in the engine block. The primary mixture conduitl terminates about mi way'of the length of the inner tube so that air moving past the end of said conduit is compelled to move in a substantially .straight path. While the tubes above described restrict the outlet branches of the manifold to some extent and thereby accelerate the How at the end of the primary mixture conduits, this restriction is not as great as in earlier forms of this device where Venturi tubes have been employed surrounding the outlets of the primary mixture conduits. For this reason, there is less tendency to reduce the volumetric efliciency by restriction of flow at the engine ports.

Disclosed in this application but forming no part of the present invention is a device for partially restricting the admission of air when the air valve approaches wide open position, which is provided for the purpose of enabling a relatively light spring to be used on the air valve so that the suction .in the air valve chamber at relatively low speeds will not be too high and result in the formation of too rich a mixture at such speeds. The device described comprises a button 210 secured'in any desirable manner to the top of the 4.air valve stem above the air valve. As shown inthe drawings this button tapers outwardly at the top so that the top is larger than the bottom. The button is adapted to lie opposite the restricted portion 211 of the air inlet passage after the air valve has made a predeterminml 'opening movement, so that further opening movement of the valve will further restrict the parsage. Obviously, the. shape of thel button may be varied to regulate the air flow as desired.

Vhile the form of embodinient of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

Vhat is claimed is as follows:

l. A charge forming device for internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary mixture. passages adapted to dcliver a primary mixture of fuel and air thereto. an air supply chamber adapted to supply an' to all oi' said primary mixture passages, a fuel reservoir, a plurality of fuel supply chambers, one for each primary mixture passage., fuel inlets connnunicating with the fuel reservoir and said fuel supply chambers to admit fuel thereto, a plurality of orifices connecting the fuel supply chambers with the primary mixture passages to supply* fuel thereto, and a. plurality of larger orifices to connect the air chamber ivith cach of the -fuel supply chambers, whereby substantially the same suction is maintained in each of the fuel supply chambers as is maintained in the air chamber.

, 2. A charge forming device comprising a carburetor unit having a primary mixture passage formed therein, means for supplying fuel and air thereto, and a manifold associated with said carburetor unit having an air passage and a mixture conduit formed therein, said mixture conduit being east entirely within the manifold walls and adapted to register with the primary mixture passage in the carburetor unit.

3. A charge forming device comprising a carburetor unit having a primary mixture passage formed therein, means for supplying fuel and air thereto, and a. manifold associated with said carburetor unit having an air passage. and a mixture conduit formed therein, said mixture conduit comprising a sheet metal tube cast in position entirely within the manifold walls and adapted to register with the primary mixture passage in the carburetor unit.

4. A charge forming device comprising a carburetor unit having a primary mixture passage formed therein, means for supplying fuel and air thereto, and a manifold associated with said carburetor `unit having an air passage and a mixture conduit formed therein, said mixture conduit having alternate. round and flat sections and adapted to register with the primary mixture passage in the carburetor unit.

5. A charge forming device comprising a carburetor unit having a primary mixture passage. formed therein, means for supplying fuel and air thereto, and a manifold associated with said carburetor unit having an air passage and a mixture conduit formed therein, said mixture conduit comprising a tube cast in position entirely within the manifold walls in position to register with said primary mixture passage and being alternately round and flat in cross section.

6. A charge forming device comprising a carburetor unit, a main air passage therein, a prunary mixture passage, means for supplying fuel and air to said mixture passage, a manifold associated with said, carburetor uint, an air passage therein adapted to register with the main air passage in said carburetor unit and a mixture conduit cast entirely within the manifold walls and adapted to register with said primary mixture passage.

7. A charge forming device comprising a carburetor unit having a main air passage and a plurality of primary mixture passages formed therein, means for supplying fuel and air thereto, a manifold associated thc'rewith having a plurality of secondary mixing chambers therein to which said primary luixture passages are adapted to deliver a primary mixture of fuel and air, an air passage adapted to register With the main air passage in the carburetor unit, and a plurality of separate primary mixture conduits for conveying the primary mixture to the secondary mixmg chambers. said conduits being cast entirely Within the manifold Walls and adapted to register With the primary mixture passages in the carburetor unit.

8. An intake manifold for internal combustion engines comprising a passage adapted to deliver air to the engine intake ports and a conduit adapted to deliver a mixture of fuel and air to said intake ports, said conduit comprising a tube cast entirely within the manifold Walls.

9. An intake manifold for internal combustion engines comprising a passage adapted to deliver air to the engine intake ports and a conduit adapted to deliver a mixture of fuel and air to said intake ports, said conduit 4comprising a tube having alternate round and flat sections.

10. An intake manifold for internal combustion engines comprising a branched passage adapt'ed to deliver air to all of the intake ports of a multicylinder engine, a plurality of separate conduits for delivering a mixture. of fuel and air to said intake ports, said conduits being cast entirely Within the manifold walls and one of said conduits being associated With each engine intake port. A 11. A charge forming device for an internal combustion engine comprising an intake passage, means for supplying fuel and air thereto, a valve controlling admission of air, a dashpot for retarding the opening of the air valve, and means for controlling the eiectiyeness o f the dash pot comprising an auxiliary cylinder communicating with the dashpot cylinder, and a spring controlled piston in said -auxiliary'cylinden 12. A charge forming device for internal combustion engines comprising an intake passage, means for supplying fuel and air to said intake passage, an auxiliary air valve controlling admission of additional air to said intake passage and ada ted to be opened by engine suction, a thrott e regulating the fiow of mixture through said passage, yielding means for preventing the opening of the air valve by suction and means o erated by ,the throttle for moving said yiel ing means to a position to permit opening of said valve.

13. A charge forming device for internal combustion engines comprising a mixture passage, means for suppl ing fuel and air thereto, a throttle controlling the fiow therefrom, a pump for supplying additional fuel to the mixture passage on o ening movements of the throttle comprising a cylinder and a piston movable therein, a rod for operating said piston connected with the throttle and having no positive connection with the piston whereby on opening of the throttle, the piston is moved to pump fuel into the mixture passage, but on closing movements of the throttle, the piston rod is operated independently of the throttle, an auxiliary fuel supply means for supplying additional fuel during certain operating conditions and means connected to said piston rod for rendering said auxiliary fuel supply means effective.

14. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying air thereto, fuel supply means operable to supply fuel to said mixture passage during normal opera-l tion, a pum adapted to supply additional fuel to sai mixture passage on opening movements of the throttle to enricl. the mixture during the acceleration period an aux- `iliary fuel supply means rendered effective by said pump, and another manually controlled auxiliary fuel supply means adapted to be rendered effective to supply additional fuel to the mixture passage whenever it 1s desirable.

15. A charge forming device for internal combustion engines comprising a`secondary mixing chamber, a primary mixing chamber in which an emulsion mixture of fuel and air is mixed with air to form a primary fuel air mixture, av mixture passage connecting said primary and secondary mixing chambers, a fuel supply chamber communicating -With the primary mixing chamber and supplying an emulsion of fuel and air thereto, means admitting fuel to said fuel supply chamber, an air chamber adapted to supply air to the fuel supply chamber, and means for maintaining within said fuel supply chamber substantiall the same suction as is maintained in the air chamber.

16. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixing chamber in which an emulsion mixture of fuel and air is mixed with air to form a primary fuel air mixture, a lmixture passage connecting said primary and secondary mixing chambers, a fuel supply chamber communicating with the primary mixing chamber and supplying an emulsion of fuel and air thereto, means admittin fuel to said fuel supply chamber, an air chamber adapted to supply air to the fuel supply chamber, an orifice connecting the fuel supply chamber with the primary mixing chamber, and an orifice of larger size connecting the fuel su ply cham, ber with the air chamber where y the suction maintained in the fuel supply chamber is substantially the same as that of the air chamber.

17. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixing chamber in which an emulsion of fuel and air is mixed with air to form a primary fuel air mixture, a mixture passage connecting said primary and secondary mixing chambers,'a fuel supply chamber communicating with the primary mixing chamber and supplying an emulsion of fuel and air thereto, means admitting fuel to said fuel supply chamber, an air chamber adapted to supply air to the fuel su ply chamber, a suction operated valve contro lin the admission of air to the air chamber, an means for maintaining within said fuel supply chamber substantially the same suction as is maintained in the air chamber, whereby the air valve controls the degree of suction maintained in the air chamber.

18. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixing chamber, a mixture passage connecting said primary and secondary mixing chambers, a fuel supply chamber communicating with the primary mixing chamber and supplying an emulsion of vfuel and air thereto, a plurality of fuel jets for supplying fuel to said fuel supply chamber and adapted to be rendered operative successively, and means for maintaining substantially the same suction in the fuel supply chamber as is maintained in the air chamber.'

19. A charge forming device for internal combustion .engines comprising a secondary mixing chamber, a primary mixing chamber, a mixture passage connecting said primary and secondary mixing chambers, a fuel supply chamber communicating with the primary mixin chamber and supplying an emulsion of fuel and air thereto, means admitting fuel to said fuel supply chamber,

an air chamber ada ted to sutpply air to the fuel supply cham er, an ori ce connecting the fuel su ply chamber with the primary mixing c amber, and an orifice of larger size connecting the fuel supply chamber with the air chamber, the sizes of said orifices being such that the suction maintained in the fuel supply chamber is substantiallythe same as that of the air cham-v ber under all operating conditions.

20. A charge forming device for internal combustion engines comprising an inta-ke passage, means for supplying fuel and air to said intake passage, an auxiliary air valve controlling admission of additional air to said intake passage and ada ted to be opened by engine suction, a thrott e regulating the flow of mixture through said passage, a member for normally preventing the openin of the air valve, yielding means for hol ing said member in effective position, and means operated by the throttle for moving said member to ineffective position.

In testimony whereof we hereto affix our signatures.

FRED E. ASELTINE. WILFORD H. T'EETER. CARL H. KINDL. 4 FREDERICK D. FUNSTON.

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