US1904634A

US1904634A - Charge forming device

Info

Publication number: US1904634A
Application number: US288685A
Authority: US
Inventors: Wilford H Teeter
Original assignee: Delco Products Corp
Current assignee: Delco Products Corp
Priority date: 1928-06-27
Filing date: 1928-06-27
Publication date: 1933-04-18
Anticipated expiration: 1950-04-18

Description

April 18, 1193' W. H. TEETER CHARGE FORMING DEVICE Filed June 27. 1928 6 Sheets-Sheet l e Sheets-Sheet 2 52 w mum, Qwm 3mm 8 a E m m m @NN. Tum HF..w Wd 8 W m CHM.

April, 18, 1933.

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6 Sheets-Sheet 3 W H TEETER CHARGE FORMING DEVICE Filed June 27.

Aprifi 118, 15%.

LQM ML o "D AFTER 1903' W. H. TEETER CHARGE FORMING DEVICE 6 Sheets-Sheet 4 Fi led June 27. 1928 April 18, 31933. I W- TEETER EEWLbEQ- CHARGE FORMING DEVICE Filed June 27, 1928 6 Sheets-Sheet 5 April 18, 1933. 1,904,634

' W. H. TEETER CHARGE FORMING DEVICE Filed June 27. 1928 6 Sheets-Sheet 6 swam tom Patented Apr, id, 1233 rattan WILFGRD H. TEETER, 0F DAYTON, OHIO,

ASSIGNOR, BY MESNE ASSIGNMENTS, T0

DELCO PRODUCTS CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELA- WARE erranen romaine nnvrcn Application filed June 27,

This invention relates to charge forming devices for internal combustion engines and more particularly to the type of charge forming device comprising a plurality of primary fuel mixing chambers or primary carburetors, one for each intake port of the engine and cooperating respectively with a plurality of secondary fuel mixing chambers or secondary carburetors each located adjacent an engine intake port and receiving fuel air mixture from a pipe connected with one of the primary carburetors While receiving air when required through one branch of an air manifold which supplies air to all the secondary carburetors. The primary carburetors receive liquid fuel from a common fuel bowl in which the level is controlled by a float valve.

Examples of charge forming devices of the character described above are disclosed in the copending applications of W. H. Teeter, Serial No. 221,372, filed September 22, 1927 which matured to Patent No. 1,819,526 granted August 18, 1931 and W. H. Teeter, Fred E. Aseltine and Carl H. Kindl, Serial No. 288,683, filed June 27, 1928. In these charge forming devices a plurality of primary carburetors are provided one for each intake port. The fuel mixture from the primary carburetors is conveyed to secondary mixing chambers located adjacent the various engine intake ports Where it is mixed with air. Throttling of the engine is efiected by a' single primary throttle which controls all the primary carburetors, and a single main throttle controlling the air flow through the main air manifold. These throttles are operated from a common operating mechanism which is so arranged that the primary throttle controls the quantity of mixture passing to the engine at speeds up to a vehicular speed of 20-25 miles per hour, after which the main air throttle begins to open and becomes the main contfirolling element regulating the mixture out The general obects of the charge formin devices disclosed in the applications referre I to are, first, to provide a mixture of fuel and air having the desired fuel and air ratio 1928. Serial N0. 288,685.

under all operating conditions, and, second, to deliver equal quantities of this mixture to each cylinder of the engine under various conditions of load and speed, Without requiring the heating of the fuel or fuel mixture before it is delivered to the engine.

Various devices are provided in these charge forming devices for controlling the flow of fuel and air under various operating conditions so as to secure at all times a mixture having the desired fuel and air ratio. Certain of these flow proportioning devices are made necessary because the air flowing through the primary carburetors moves past the jets at such high velocity that it creates at said jets a velocity head which is effective to cause flow of fuel therefrom. This velocity head which is present at the fuel jets causesa too rapid increase in fuel flow on increase of engine speed resulting in too rich a fuel mixture unless some means is provided to compensate therefor. Because the excess of fuel in the mixture is a variable thing dependent on a number of diflerent factors it has been found almost impossible to correct the eflect of the velocity head on fuel flow by any one device, and very difiiculfl to secure a mixture having the desired fuel and air ratio under all operating conditions by use of any proportioning devices heretofore known.

The charge forming device forming the subject of the present invention is of the same general type as those disclosed in the above mentioned applications and the principal object of this invention is to provide a charge forming device of this character in which fuel is caused to flow from the jets by the static suction Within the carburetor, and in which the efi'ect of velocity head on the fuel flow is substantially eliminated under all operating conditions. A further object of the invention is to provide a charge forming device having improved and simplified mechanism for proportioning the fuel mixture so as to provide fuel mixtures of the desired proportions to most successfully operate the engine under all possible operatingconditiona Further objects of the invention are to provide a charge forming device of the characduced and to provide a device of this character having a substantially symmetrical design.

With these objects in view one feature of the invention resides in the provision of a plurality of fuel jets to each of which the static suction of the main air chamber is communicated through a passage of considerably greater area than the outlets through which fuel flows into the high velocity air current passing through each primary carburetor. By means of this construction the static suction of the main air chamber is made the principal factor controlling the flow of fuel at all engine speeds.

A further feature of the invention consists in the provision of means, normally ineflective, but rendered eflective by the choke device, to admit a small quantity of air to carry the starting fuel to the engine when the main air valve is held closed by said choke device when the engine is to be started.

A further feature of the invention is a novel form of accelerator pump for supplying a predetermined quantity of additional fuel for acceleration whenever the throttle is opened, irrespective of the position of the throttle at the beginning of its opening movement.

A further feature of the invention resides in the provision a simplified form of sec ondary air valve and dash pot controlling the movements thereof.

An improved and simplified mechanism for connecting the primary and secondary throttles to a common operating means forms a still further feature of the invention.

Still further features .of the invention reside in the provision of means connecting the primary carburetors with the main air chamber whereby substantially all the air entering the primary carburetor must come from the main chamber, and an improved form of fuel inlet means which admits, fuel to each primary mixture passage which comprises a plurality of fuel ports in the wall thereof between the inlet end of said passage and the primary throttle.

The present invention is embodied in a charge forming device comprising an air manifold which does not include any of the control mechanism of the carburetor, and a main carburetor unit adapted to be attached to and supported by the air manifold, said unit including the fuel bowl, the primary carburetors to which li uid fuelis distributed from the fuel bowl, an all of the valves and control mechanism associated therewith for controlling the flow of air through the air manifold and the flow of primary fuel mixture from the primary carburetors to the secondary carburetors at each engine intake port. The primary mixture is conducted from the primary carburetors to each of the secondary carburetors through pipes constructed in a manner described in detail hereinafter and communicating with three passages in the manifold wall which register, when the carburetor unit is attached to said manifold with the primary mixture passages in said unit. In this way the carburetor unit may be readily attached to or detached from the air manifold, permitting the manufacture of the air manifold as separate units.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of embodiment of the invention is clearly shown. 1

In the drawings:

Fig. 1 is a plan view of a form of the present invention.

Fig. 2 is a front elevation of the device shown in Fig. 1.

Fig. 3 is an elevation of the carburetor unit viewed from the left in Fig. 1, partly broken away to show certain parts in section.

Fig. at is a view similar to Fig. 3 viewed from the right in Fig. 1.

Fig. 5 is a detail section on the line 5-5 of Fig. 2. I

Fig. 6 is a vertical. section through the carburetor unit on the line 6-6 of Fig. 2.

Fig. 7 is a transverse vertical section through the carburetor unit on the line 7-7 of Fig. 6.

Fig. 8 is a horizontal section on the line 88 of Fig. 6.

Fig. 9 is a horizontal section on the line 99 of Fig. 6.

Fig. 10 is a vertical section on the line 10-10 of Fig. 6.

Fig. 11 is a fragmentary vertical section on the line 1111 of Fig. 6.

Fig. 12 is a fragmentary section on the line 12-12 of Fig. 6. v

Fig. 13 is a detail view of the choke lever and air admission means controlled thereby.

Fig. 14 is a detail View of the operating connections for the throttle valves.

Fig. 15 shows a'modified form of fuel jet.

Fig. 16 is adiagrammatic, sectional view.

to supply fuel mixture to two adjacent cylinders of the engine. The air manifold 20 is adapted to be secured to the cylinder block in the same way as the conventional intake manifold is attached to the cylinder head. Adjacent its intake the manifold 20 is provided with a flange 26 to which may be secured the carburetor unit which will now be described.

The carburetor unit comprises two main castings, a housing 28, and a frame 30, positioned just below the housing and secured thereto by screws 32, see Figs. 2 and 4. The housing 28 is provided with a flange 34 which is attached tov the manifold flange 26 by screws 36 when the device is assembled. The housing 28 contains the main air chamber, air inlet valve, primary carburetors, throttles and other mechanism later described, while the frame 30 has formed therein various dash pots for controllin admission of air and other devices more ully described hereinafter. In addition the frame 30 pro vides the top for a constant level fuel chamber formed by a sheet metal fuel bowl 38, the upper edge of which fits against a shoulder 40 formed on a projecting flange 42 of the frame 30, the bowl being held tight against the shoulder 40 by a screw 44, screwed into the frame 30. A gasket 46 is provided between the head of screw 44 and the bowl to prevent leakage and a gasket may be fitted on shoulder 40 if desired. A gasket 48 is provided between the housing 28 and frame 30.

A fuel pipe 50 leading to a main fuel supply is screwed into a boss 52 on housing 28 to conduct fuel to the fuel bowl 38. A passage 54 in the wall of housing 28 communicates with said boss and re 'sters with a passage in the frame 30 in which is screwed a nipple 56, as shown in Fig. 4. The passage through the nipple is restricted at 58 to form a seat for a valve 60, operated by a float 62 to control the flow of fuel to bowl 38 in the usual way. The float is of hollowmetal construction, semiannular in form, and provided with

arms

64 and 66 secured to its two ends by solder or otherwise. These arms are pivoted on pins 68 which are loosely mounted in'a depending portion of the frame 32, and are held in position in said frame when the device is assembled by engagement of the fuel bowl with the outer ends of said pins, as shown in Fig. 9. The valve 60 rests on the arm 64 and is opened and closed during vertical oscillationof the float to regulate the level of liquid in the fuel bowl in a manner well known.

Fuel is conveyed from the fuel bowlto the primary carburetors which will be more fully described later through an angular. passage 70 bored in a portion of the frame 30 as indicated in Fig. 10. The lower horizontal portion of the passage connects with a veroperation.

.buretors up to the vehicular speed above referred to, after which a fuel valve '76 received in the upper part of the vertical passage 72, and normally seated on a restriction 7 8 in said passage is lifted by means hereinafter described to permit fuel to flow through an auxiliary fuel port 80, past valve seat 78 to passage '70 to augment the fuel flowing.

through the plug 74.

The fuel passage 70, at its upper end communicates with a horizontal fuel canal 82 formed in the upper face of the frame 30. This canal communicates with three calibrated plugs 84, screwed into the lower face of the housing 28 and each connecting with a vertical passage 86 bored in the wall of the housing 28 as shown in Fig. 6. Each of said passages 86 communicate with one of three parallel primary carburetors, indicated in their entirety by the numeral 88, to supply fuel thereto. After the valve 76 is lifted as previously described to render the port effective to admit fuel, the calibrated plugs 84 meter or regulate the flow of fuel per unit of time to the primary carburetors.

Each of the primary carburetors comprises an angular mixture passage having a horizontal outlet portion 90 and a "e-rtical inlet portion 92. These passages are in substantially parallel vertical planes and are bored in the bottom wall of the main housing 28 which may be termed the distributor block, for convenience. The Vertical inlets 92 communicate with the main air chamber 94, formed in housing 28 and more fully described later, all of the air flowing through the primary carburetors at all engine speeds being taken from said main air chamber, in which the suction at any engine speed is a static suction determined by the action of a spring held main air valve, the construction and operation of which will be described in detail hereinafter.

Associated with each primary carburetor to supply fuel thereto is a fuel passage 86, previously described. Each passage 86 is formed in the wall of housing 28 closely adjacent and substantially parallel to the vertical portion 92 of the primary mirture passage with which said passage 86 is associated. Each passage 86 is provided at its lower end with a small fuel inlet orifice 96, which admits fuel to the passage 92 for low speed Each passage 86 communicates with a horizontal passage 98, bored in the wall of housin 28 a short distance above the orifice 96, and having its outer end closed by a plug 100. The diameter of the passage 98 at its point of joinder with the passage 86,

is appreciably greater than that of passage 86, and said passage 98 is provided with a restricted end 102 communicating with the passage 92 and constituting a main fuel inlet orifice therefor, which is ineffective at low E speeds but comes into operation at higher.

speeds to augment the-flow of fuel from the inlet 96. Bored in the wall of the housing 28 are three passages '104 connecting with.

the passages 98, which connect said passages 98 with the main air chamber 94, to communicate the suction of said chamber to the passages 98.

It will be obvious on consideration of the above described structure, that .the suction,

which is effective at any engine speed,to lift fuel from the fuel bowl through the metering plugs 74 and 84 to the

fuel feeding orifice

96 and 102 is substantially the static suction maintained in the air chamber 94, rather than the suction of the primary mixture passages which is dependent primarily on the velocity of flow through such passages.

The passages 86 are in communication with the air chamber 94 through

passages

98 and 104, and communicate with the primary mixture passages solely by means of the orifices- 96 and 102, the combined area of which is considerably less than the cross sectional area of either

passage

98 or 104.

' In order for a velocity head to be created in the passages 86 and thus become effective to control the fuelflow, it would be necessary for air to flow from chamber 94, through

passages

98 and 104 and through the

orifices

96 and 102 to the primary mixture passages at high velocity. While there is a greater degree of vacuum maintained in the mixture passages than in chamber, 94 and a flow of air will take place through the various passages as described above the velocity of such flow can never be suflicient to create a velocity head because the area of

passages

98 and 104 is much greater than the combined area of

holes

96 and 102. A current of air will be moving through passages 98 and104, but at all points between

orifices

96 and 102, and the connection of passage 104 with the air chamber 94 the pressure will be substantially that.

.65

sages

98 and 104 must be the controlling factor efiecting the flow of fuel to the passages 86, under all conditions of engine operations and speed.

The flow of primary fuel mixture through the primary carburetors is controlled by 0 'means of a single primary throttle valve 106,

which extends across all of the horizontal passages 90 and has grooves 108 formed therein which register with the said passages 90 as indicated in Fi 8. This throt- 7 tle is journalled in a suite 1e recess 110 of the same diameter as the throttle bored in the bottom wall of the housing 28. The ends of the throttle are reduced in size to form spindles 112 and 114, which project beyond the walls of housing 28, and on which are secured, by set screws, certain valve operating connections hereinafter more fully described. These valve operating connections engage the outer walls of housing 28 and prevent any longitudinal movement of the primary throttle, maintaining the grooves 108 in accurate registry with the passages 90.

The passages connect, at their posterior ends, with passages 91 formed in the man'i- 90 fold wall and are associated with pipes which convey the primary mixture to secondary mixing chambers where it is mixed with additional or secondar air during operation of the engine at big er speeds These pas-- sages 91 are'not a part of the main carburetor, but, as indicated, are .formed in the wall of the air manifold, the latter with the conduits formedwtherein and pipes associated therewith, being manufactured as a unit separate from the carburetor.

All of the air admitted to either primary or secondary mixing chambers, except a very small quantity which is admitted when the choke lever is operated to facilitate starting, enters the carburetor through an air inlet horn 116, secured by screws 118 to the top, of housing 28, and adapted to be connected to an air cleaner or other form of air intake connection. The horn 116 is provided with 21. restricted throat 120 at the apex of two

conical surfaces

122 and 124, the surface 124 ,providing a seat for a valve 126, which con trols the entry of air into chamber 94, which is held against its seat when the engine is not running by a compression spring 128. h

The valve 126 is secured to a coupling member 130 which is pinned to the upper end of a valve stem 132, slidably mounted in a guide sleeve 134, secured at its lower end in an orifice formed in the bottom wall of the housing 28 and is supported by a flanged plug 136 which fits tightly within a cylindrical recess 138 formed ,inthe wall of the housing 28. The guide sleeve is forced downwardly into the plug until a shoulder 140 thereon engages the upper face of said plug. That part of the guide sleeve 134 above the plug 136 is enlarged and slidably mounted thereon is a concentric sleeve 142, having a flange 144 secured to its lower end which provides a support for one end of the compression spring 128.

A choke lever 146 is pivoted by means of a pin 148 mounted in bosses 150 projecting from the housing 28. The lever 146 projects through the wall of the housing and the inner end of said lever underlies the flange as shown in Fig. 7. H the lever 146 is moved to the position shown in Fig, 13, the sleeve 142 will be lifted and the spring 128 compressed. By partial operation of the choke lever the force of the spring 128 tend ing to prevent opening of the valve may be regulated as desired, and a complete operation of the said choke lever; will move the sleeve 1 1-2 upwardly into engagement with the valve 126, holding said valve entirely closed for starting of the engine,

is necessary, however, for some air to be admitted when the carburetor is choked, to ca y the liquid fuel to the engine cylinders A to form with said fuel a mixture which an t w l burn. Heretofore a small fixed port has been provided or the air valve has been allowed to open a slight distance to admit a small quantity of air when the choke mechanism is operated. Both oi? these means'lor admitting air have, however, caused improper proportioning of the mixture llt will be obvious that it the air valve spring is of proper tension to admit the correct amount of air as the throttle is opened through different degrees, any admission oi": additional air through a fixed port or any me us to open the valve slightly on starting cause an excess of air to be admitted to the carburetor. llhis excess of air constitutes a greater proportion of the whole quan of air admitted at low speeds than at i l higher speeds, resulting in greater disturbance of correct mixture proportions at low speeds. in the device disclosed means are provided to admit a small'amount of air vien the choke is operated, but which is rendered ineffective as soon as the cholre mechanism is moved to its normal inoperaposition, to prevent admission of this excess air during normal operation. of the carburetor. For this purpose the choke lever is provided with a flat surface 152 ad jacent its pivotal mounting. lillhen the lever is operated to hold the air valve closed and occupies the position shown in Fig. 13 the H see 152 occupies a position such as to lea e a small passage between the wall of the boring and said llat surface, permitting the entry of a small quantity of air into the housing. l/Vhen the choke lever is moved to its normal position, the curved surface of the choke lever hub is brought into engagement with the similarly curved surface of the housing wall to close the passage above de scribed and prevent admission of air therethrough,

To determine the normal inoperative position of thechoke a set screw 154i is screwed into a lug 156 cast integral with lever 1 16 and is adapted to engage the wall of housing 28 to limit the movement of said lever toward the wall. To yieldingly retain the set screw in any adjusted position a pointed flat spring 158 is riveted or secured in any other desirable way to the lever 14:6 so that the pointed end thereof engages the knurled head of set screw15 l.

To prevent fluttering of the air valve and to retard its movement toward open posi tion for purposes of acceleration, a dash pot is provided includin a cylinder 166 positioned within the the bowl and formed in. a depending part of the frame 30.. Received within the cylinder is a piston 162 slidably mounted on a sleeve 164 secured by a pin 166 to the lower end of the valve stem 132 and provided at its lower end with a flange 168 having an annular rim 170 formed on its upper face, The piston is normally held seated on said rim by a compression spring 171 received between an up-turned annular flange 172 surrounding the central opening in the piston in said sleeve 164-. is received, and a collar 174i screwed. on the upper end of the sleeve. Holes 17 6 are pro:- vided in the bottom. of the piston 162 to permit passage or therethrough for the purpose of relieving the dash pot and permitting rapid opening or the air valve under certain operating conditions to be later described The bottom of "the cylinder 166 is closed by a cap 178 soldered, or otherwise secured to the cylinder walls, so as to term a tight joint. At the center of the cap is a valve cag 180 having a fuel inlet orifice 162 therein. \pheclr valve 164; is provided within the valve cage to permit blow of fuel the cylinder on the up stroke oil piston 162, but preventing out llow oi fuel on the down stroke oil said piston.

During operation at all engine speeds below that corresponding to a vehicular speed of 2(l 25 miles per hour on a level all the air entering the air manifold passes through the primary carburetors, the mixture formed therein being of properly combustible proportions. At speeds in excess of that mentioned, however, the primary mixture pas sages are of insufficient capacity to provide a sufiicient quantity of mixture to the en gine cylinders, and unless additional air were admitted to the engine cylinders the mixture entering the cylinders would be under such a high vacuum that a serious loss in. volumetric eliiciency would result. 'llo obviate this difiiculty the valves controlling the ilow of air through the secondary air passage are opened after the engine speed referred to has been reached.

Flow of air through the secondary air pastill sage is controlled by two valves, a manually operated butterfly throttle 186 and a suction operated valve 188. The throttle 186 is fixed on a shaft 190, j ournalled for rotation in the walls of the housing 28, and is operated si- The mechanism for operating the throttle valves will now be described. Adjustably secured to the spindle 112 on the primary throttle, by means of a set screw 194 or other suitable means is an operating lever 196, one

- arm of which, is provided with an eye 198 in which is adapted to be connected a Bowden wire or other suitable connectionextending to a point convenient to the operator. An arm 200 of said lever has pivotally connected thereto by a bolt 202 a square tube 204,

the bolt passing throu h an ear 206 projecting from said tube. 1% slot 208 is provided in the wall of the tube adjacent the housing 28 and projecting through the slotis the shank of a bolt 210, secured in one end of an operatingarm 212 adjustably secured to the end of shaft 190 by a set screw 214. v The lower end of the tube 204 is closed and received in said tube between the closed end and a bent metal cap 213 freely slidable in the tube is a compression spring 215 which tends to hold the bolt 210 in the upper end of slot 208 at all times. When, however, the lever 196 is moved in a clockwise direction to close the two throttles, the secondary throttle 186 reaches closed position before the primary throttle. During subsequent clockwise movement of the lever 196 to close the primary throttle, the spring 215 is compressed and the square tube 204 is moved upwardly, so that when boththrottles are closed the arts are in the position shown in Fig. 14 wit the bolt 210 positioned in the lower end of the slot 208. The closing movement of the rimary throttle may be limited as desire by means of a stop screw 216 adjustable in a lag 218 projecting from the" housing 28 and held in ad usted position by,a lock nut 220. The screw is adapted to be engaged by a toe 222 rojecting laterally from an arm 224 of the ever 196 as. the latter is moved in a clockwise direction.

.It will be clear that the pin and slot connection described above constitutes a lost motionconnection between the two throttle valves Permitting a definite amount of o eration 0 the primary throttle entirely independent of thesecondary throttle. When tubes.

208, after which the two throttles are moved simultaneously. In the device disclosed herein the parts are so proportioned that the primary throttle opens to a position giving an engine speed corresponding to a vehicular speed of 20-25 miles per hour before the bolt 210 is engaged by the upper end of slot 208 to open the secondar throttle.

When the secondary th the suction in the air chamber 94 below the air valve 120 is greatly increased resulting in so great an inrush of air that, although the opening movement of the air valve is to some extent retarded, the flow of air into the air manifold past the secondary throttle 186 would be so great as to temporarily lean the mixture unless some means Were provided to retard the flow of air through the secondary air passage. This action is due to the fact that the primary mixture flows more slowly than pure air because of its greater density. Moreover, Whenever either throttle is opened to accelerate a richer mixture is necessary for a short interval of time, and means described in detail hereinafter, is provided to force an additional quantity of fuel into the primary mixture passages whenever either throttle is opened for acceleration to provide a mixture of desired proportions. Owing to the density of this rich primary mixture it requires an ap )reciable time to convey said mixture from t e primary mixture passages,

and the lower the pressure differential between the inlet and outlet ends of said pri-' mary mixin tubes the greater time interval required. n openin of the secondary rottle 186 is opened throttle 186, there would be an inrush of air pastsaid throttle which would not only tend to dilute the mixture as above set forthbut would cause a. drop in the pressure differential-between the two ends of the primary This would increase the time interval necessary for the primary mixture to reach the secondary mixing chambers, and since the air is much lighter than the primary mixture, would result in the secondary air reaching the secondary mixing chambers before the ,9 enriched primary mixture causing a starving of the motor.

The suction operated air valve 188 is therefore retarded during its opening movements for two reasons: first for producing-at all times, when the throttle 186 is open, a sufficient pressure differential between the inlet and outlet ends of the primary mixing tubes tubes great enough to transport the primary the throttles are to be opened, the lever 196 1 mixture from the primary mixing chambers 1s moved in a counter, clockwise direction to the secondary mixing chambers substaneo aces tially instantaneously: second, to prevent admission of a suflicient quantity of air through the secondary airpassage to temporarily lean the mixture.

To control the movement of the air valve l88 said air valve has an arm 225 secured to its anterior side, as shown in Figs. 6 and 11 by brazing or in any other suitable way. The free end of this arm is pivotally connected to a short link 226 by a cotter pin 228 which extends through a short slot 230 in the link and a hole in the arm. The link 226 is pivotally connected to a bifurcated head 232 screwed on the end of a piston rod 234, and provided with two upstanding arms 236, each of which has a slot 238 formed therein. A cotter pin 240 extends through said slots and a hole in the lower end of link 226 which is received between the two arms when the parts are connected together as shown in Fig. ll.

llhe piston rod is loosely received in a bore 242 in the bottom of housing 28, the bore providing a guide for the rod during vertical movements thereof. Pinned to the lower end of the rod 23% is a sleeve 242 and slidably mounted on the sleeve is a piston 244- which tits within a dash pot cylinder 246, closed at its lower end by a cap 248, secured to the cylinder in any desirable way toprovide a fluid tight joint. The piston is normally held in its uppermost position to hold the valve closed by a spring 250 and opening movement of thevalve is opposed by the force of the spring and the upward pressure against the piston of the liquid in cylinder 246 below said piston, liquid fuel is admitted to said cylinder from the float chamber by leakage around the said piston and through a passage way formed between the rod 234 and sleeve 242, the rod being somewhat smaller than the internal diameter of said sleeve. A check valve 252 is seated in the enlarged lower end of the sleeve 242 and operates to prevent flow of fuel from the dash pot cylinder to the above described passage on downward movement oi the piston, while permitting passage of fuel into the cylinder as the piston moves up. Any suitable means may be substituted for the spring 256 so as to return the piston 244 to its normal position when the air throttle is closed.

The sleeve 242 is provided with a flange 254 having an annular rim 256 formed on its upper face against which the piston is normally held seated by a spring 258 received between an upturned annular flange 260 surrounding the central opening in the piston through which sleeve 242 passes and a collar 262 screwed on the upper end of the sleeve. l-loles 264i are provided in the bottom of the piston to permit passage of fuel through the piston when the latter is lifted from the annular rim 256, under certain operating conditions hereinafter described, to relieve the dashpot and permit rapid opening of the valve. During normal operation the piston is seated on the rim 256, the piston and rim constituting a valve, preventing flow of fuel through the piston and enabling the dashpot 'to retard the opening movement of valve 188 during opening movement of the throttles.

Under certain operating conditions, when the suction edective to open the

valves

126 and 188 is very suddenly and very greatly increased the pistons 162 and 244: are both moved downward so rapidly that the resistance to their motion is great enough to overcome the pressure of

springs

171 and 258 and lift the pistons 162 and 244: from the

annular rims

170 and 258 respectively thus permitting fuel to flow from below both of said pistons and through the holes therein allowing both

valves

126 and 188 to open freely. After the pistons are lifted from the

rims

170 and 256 they will not reengage such rims until the pressures against the lower side of the pistons become less than the pressures of the springs which normally hold the pistons in engagement with said rims. It will be clear that the pressures required to hold the pistons above the rims are much less than the pressures required to initially lift the pistons, because such pressures are effective on the entire lower face of each piston while the pressures effective to initially lift the pistons are applied only to those portions of the pis tons which extend beyond the flanges 168 and 254. As an example of operating conditions when the pistons will be lifted as de: scribed, it may be assumed that the vehicle is volume of charge to give the necessary power. l

lit will be noted that the device disclosed herein differs from those disclosed in the prior applications referred to above in the construction of the throttle 186 and valve 188. lln

ally operated throttle tended to operate the l other valve. The construction disclosed herein is considerably simpler, but the yielding connection previously used, or other form of connection, may be embodied herein to aid in controlling the opening movement of the valve 188, if desired.

As indicated hereinbetore a device is provided for enriching the mixture whenever the throttle is opened for purposes of acceleration. This device comprises a pump as mounted within the said cylinder is a piston- 270, provided with a vertical bore 272 therein, connectedat its upper end by a series of small passages 274 with an annular channel 27 6 formed in the periphery of the piston. Normally when the parts within the carburetor are at rest at any engine speed the piston 270 occupies the pisition shown in Fig. 6 at the bottom of the auxiliary cylinder, seated on a flange or ledge 278 projecting inwardly from the cylinder wall and closing a port 280 eonnecting the interior of the auxiliary cylinder with the main fuel chamber. In this position of the piston the channel 276 connects with a right angled passage 282 bored in a portion of the frame cast integral with the auxiliary cylinder. This passage is connected by means of two passages 284 with a 30 fuel channel or canal 286 formed in the upper face of the frame 30 as shown in Figs. 6 and 12. Three outlet passages 288 having restricted upper ends 290 connect the fuel channel 286 with the primary mixing chambers at a point immediately below the axis of the primary throttle valve. Bored in the bottom wall of the housing 28 are two passages 292 connecting the upper part of the float chamher with the fuel channel 286, to admit an to said fuel channel from the space above the fuel in the float chamber, said space being in communication with the outside atmosphere "through the elongated passage 294 in the wall of housing 28 as shown in Figs. 4 and 7.

The above described pump operates as follows. With the parts at rest, at whatever speed the engine may be running, the piston 270 occupies the osition shown in Fig.6,

I with the channel 2 6 in registry with the fuel passage 282. Any opening of the throttle for acceleration will be accompanied by a downward movement of the dash pot piston 162, which. will force fuel through the

passages

266, 272, 274, channel 276 and assage 282 to the channel 286 whereit is mlxed with air to form a super-rich emulsion of fuel and air which is drawn through the passages 288 into the primary mixture passages to enrich the mixture therein. During this Go action a pressure is built up on the fuel which will lift the auxiliary piston when the pressure reaches a predetermined degree. The lifting of the auxiliary piston moves the channel 27 6 out of registry with the passage 282 and simultaneously opens the port 280, so that any further downward movement of the piston 162 will merely force fuel from the dashpot cylinder 160, back into the main fuel chamber through the port 280. After the air valve comes to rest the piston 270 will fall by action of gravity and again assume the position shown of fuel into the primary mixture passages to enrich the mixture whenever the throttle is opened. This form ,of accelerator pump is deemed more desirable than those shown in the prior applications mentioned above, which are variably effective, and if operative to supply the proper amount of fuel when accelerating at one speed, may supply too "little or too much fuel when accelerating at other speeds.

Inaddition to the accelerator pump, me-' chanically operated means are provided to admit additional fuel at high engine speeds and to continue admitting such fuel as long as the engine runs at such speeds, to give the power necessary for proper operation at high engine speed. This means includes the fuel valve 76, hereinbefore briefly mentioned, which is opened at an engine speedcorresponding to a vehicular speed of approximately 50 miles per hour on a level, to admit additional flow of fuel to the fuel passage 7 0 through orifice 80. The valve 76, during operation at all s eeds up to that referre to, isheld closed y a spring'300 as shown in Figs. 3 and 10. At its upper end the valve stem is formed with a reduced neck 302 which is engaged in a. slot formed in an ear 304 projecting inwardly toward the housing 28 from one end of a lever 306, pivoted on a screw 308 screwed in said housing. At its opposite end the lever 306 is provided with an outwardly projectinjiear 310 which underlies a cam 312 adjusta ly secured by a set screw 314 on the spindle 114 of the primary throttle. The cam is formed with two

high points

316 and 318 havin a concentric surface 320 between said hig points. In Fig. 3 the cam is shown in the position it occupies when, the primary throttle is completely closed. As the primary throttle is opened the cam moves. in a clockwise direc-' tion from the position shown in Fig. 3 and since the low surface of the cam between the two

points

316 and 318 is almost concentric with an abru t rise at the point 316, no motion of the valve 76 is effected until the point 316 of the cam engages the ear 308, which ocaccessecurs when the engine reaches the speed pre viously mentioned. Since the rise of the cam point 316 is very abrupt the valve 70 is opened wide during a very slight movement of the cam and is held in that same position by the surface 320 during the entire remains ing movement of the cam until maximum speed is reached.

The means for conveying the primary mixture from the carburetor unit to the sec-= ondary mixing chambers and the construction of such mixing chambers will now be described. While these devices are of substantially the same construction as in the carburetors shown in the prior applications above referred to and constitute no part of the present invention, they are briefly described herein to enable the invention to be readily understood without reference to other disclosures.

Each of the outside primary mixture passages 90 is in registry with a passage 91 of elbow shape formed in the manifold 20. Screwed into the opposite end of each elbow shaped passage is a pipe 324, the opposite end of which is screwed into an elbow 326-, having a flange 328 attached to a hat surface on a boss 330 projecting from the manifold, by screws 382. The passage through each elbow 3% is in direct communication with a primary mixture pipe 3% extending through each outer branch 2d of the manifold. The center one of the primary mixture assages 90 is in direct communication with t e primary mixture pipe 33 i received in the middle pas sage 9i and extendin through the central branch 2A2 of the manifold to the secondary mixing chamber formed therein.

it has been found advantageous to surround the end of each primary mixture pipe 334 with a Venturi tube 336 which constitutes the secondary mixing chamber. An external rib 338 is provided on the Venturi tube and is received, when the manifold is attached to the engine bloclr, in a recess 84: 0. in

i end of the manifold and a corresponding recess (not shown) in the block. The ven turi is held fixed in position by a shoulder 34?; on the manifold and a corresponding shoulder on the en inc block on aging oppo site sides of the ii 338. The enturi tube not only increasesthe velocity of air flowing through the branches of the manifold at the inlets of the pipes 334; which results in better mixing of the fuel and air in the secondary mixing chambers, but also increases the suction at the end of the pipes 334;, thus increasing the velocity of the primary mixing flowing through such pipes which aids in acceleration of the engine. Other flow accelerating means may bsubstituted for the venturi if desired. I

it will be noted on examinationof Fig. 8 that the stem 132 of the main air valve in this device and the guide sleeve therefor pass through the middle one of the three primary mixture passages 90. To prevent any increase in velocity of the primary mixture at this oint withresulting variation in vacuum condltions in this mixture passage said passage is enlarged immediately ad acent the air valve stem as indicated at 350 so that the area of the passage around the guide sleeve is substantially the same as the area of the passage elsewhere throughout its length.

The advantages secured by elimination of the velocity head as the controlling factor regulating fuel flow will be best understood by a consideration of the dificulties caused by the presence of a velocity head in prior carburetors of this type, such as those disclosed in the above mentioned applications. @wing to the presence of the velocity head the fuel jets in such carburetors are calibrated somewhat smaller than they should be to give the economical fuel mixture ratio of to l, proper for medium" speeds, if the flow of fuel from said jets were determined by air valve suction. Up to an engine speed of substantially 1000 lit. 1?. lift. part throttle the velocity head is increased slowly and is efilective to produce a flow from the jets which is approximatel correct to give the desired mixture ratio a ve referred to. At engine speeds above 1000 iii. P. M. part throttle the velocity head builds up so rapidly that the fuel flow at an engine speed corresponding to miles per-hour vehicular speed, would be as great as the engine requires at 2000 lit. P. M. open throttle.

The velocity effect on the jets must be reduced therefore, at speedsv beyond 1000 P. and to do this the secondar throttle corresponding to the valve 186 oft is device is connected to the primary throttle and timed to begin opening at about 1000 it. P. M. which corresponds to a vehicular speed of 20 miles per hour. @win to the large diameter or the secondary t rottle and consequent rapid increase in volume of air flowing past said throttle per degree of-rota tion, the velocity of air flowing past the jets is very rapidly lowered being practically eliminated at something more than 1500 it. P. M. Since the jets are calibrated to give the proper fuel mixture up to l000 it. P. M. when the flow therefrom is con trolled by the velocity, the reduction in velocity head at speeds above 1000 R. P. M. when the secondary throttle is open causes a reduction in fuel flow below that necessary for a 15% to 1 mixture of air and fuel. This necessitates an additional flow of fuel which is accomplished by opening a needle valve and permitting fuel to flow through an aumiliary fuel passage. The needle valve is lifted through the cam 312, the contour of which is designed to admit just enough additional fuel to compensatefor the loss in suction on till Mill

llllll lllll lllli the fuel jets due to reduction in velocity head efi'ective thereon.

must be also of exactly the right size and accurate timing of operation of the two the located in exactly the right position. Since it is attempted to correct the velocity head which is a variableand unstable force by a mechanically operated means it is difficult to obtain the s nchronization of operation above referre to, and if such synchroniza-. tion is secured it will be disturbed by wear or by dimensional variations, or by any of the parts becomin loose.

By eliminating t e velocity head at the jets, and employing a metering jet calibrated to permit flow of fuel suflicient to give a fuel mixture in the proportion of 1'5 to 1 when the fuel flow is governed by engine suction as determined by the s ring held main air valve, the variation in uel flow on opening of the secondary throttle will disappear-and there will be no need to open the needle valve to admit additional fuel except for :full throttle operation. Therefore, the need of throttles with each other, or with the needle valve will disappear. v

In Fig. 15 is shown a modified form of fuel inlet means, by means of which the effect of impact of the air entering the main air intake on the flow. of fuel from said fuel inlet is revented altogether. In the form shown in Fi s. 1.to 14 the impact of the enterin air will roduce little or no effect on ow of fu'e because the passage 104 is considerably offset fromthe direct path of air flow which is through the passages 92. However, in the modification shown in Fig. 15 means are provided to prevent any possibility of a disturbance in the fuel'flow due to air impact- To this end the intake of pass e 104 is not in the floor of the air cham r as'shown in Fig. 6. Instead, the wall of housing 28 is cast with a thickened .portion 360 extending above the floor of the air chamber and projecting into the chamber. The passage 1041s bored in thisportion 360 .of the housing wall and communicates with the jet through a passage 362 formed in the vertical wall of the part 360. The bore 360 is thus closed at itsmpperendand communicates with the air chamber through the passage 362 which is substantially perpendicular to the path of the air flowing through such chamber and the effect of impact is en-' 7 ,p revented. r

nyhn be noted thatthe device disclosed herein is symmetrical, that is, the air maniat high velocity, a fuel fold and the carburetor are so desi ed that when the carburetor. unit is assem led and attached to the *manifold a vertical plane passing through the axis of the middle ranch of the manifold substantially divides the carburetor in two egual parts. In other words, the main parts 0 the'carburetor unit, namely the air chamber 94, the secondary air passage 22, the distributor block, frame 30 and fuel reservoir 38 are divided by such a vertical plane into substantially equal parts lying on opposite sides thereof. Two important advantages are secured by this symmetrical construction. First the formation of eddies and resulting turbulence in the ingoing mixture is much reduced by camparison with the device shown in the above mentioned applications, making it easier to control the mixture proportions and distribupass at high velocity, a fuel passage, fuel inlet means connecting said fuel assage and the mixing chamber, an air cham r for supplying air to said mixing chamber, and

means for making the static suction of the air chamber the dominant factor controlling the flow of fuel into the mixing chamber, comprising a passage connecting the air chamber and fuel passage which is of greater size than said fuel inlet means.

2. A charge forming device for-internal combustion engines comprising a i i g \-I chamber through which air is adapted to pass ssage, fuel inlet means connecting said fuel passa e and the mixing chamber, an air chamber or suplpjlyin air to said mixing chamber, a spring e d va ve for controlling flow of air into said-air chamber, and means whereby the tension of the air'valve spring determines the suction effective to control the flow of fuel into said mixing chamber, said means comprising a 8. A charge forming device for internal combustion engines comprising an odd number of primary mixing chambers, means for supplying fuel and a r to said chambers, a main air chamber positioned above said primary mixing chambers, an air valve admitting air to said chamber, a stem supporting ltl neonate one of said primary mixture passages, and an enlargement in said passage adjacent said stem, so that the unobstructed area of said passage is the same throughout its length.

l. charge forming device for internal combustion engines comprising an air inlet chamber, a fuel reservoir, a plurality of secondary mixing chambers, a distributor block having a plurality of primary mixture passages formed therein and adapied to deliver primary mixture to a plurality of secondary mixing chambers, and a secondary air passage supplying air to said mixing chambers, said fuel reservoir, air inlet chamber, distributor block and secondary air passage being so arranged that the center of each lies in a single vertical plane.

5. A combustion engines, comprising a primary mixing chamber, an air chamber supplying air to said rimary mixing chamber, a secondary mixing chamber into which the primary mixing chamber is adapted to deliver a primary mixture of fuel and air, and means 7 the static suction Within the air chamber the dominant factor controlling the supply of fuel to said primary mixing chamber, said means comprising a fuel supply pas sage having an outlet communicating with the primary mixing chamber and means for communicating the air chamber suction to said fuel passage.

6, A charge forming device for internal combustion engines, comprising a primary mixing chamber, an air chamber for supplying air to said primary mixing chamber under all operating conditions, and to said secondary mixing chamber under certain op erating conditions, a valve for controlling the flow of air from said chamber to the secondary mixing chamber, and means making the static suction within the air'chambcr the dominant factor controlling the supply or" fuel to said primary mixing chamber, said means comprising a fuel supply passage having an outlet communicating With the primary mixing chamber, and means for communicating the air chamber suction to said fuel. passage.

7. A charge forming device for internal combustion engines, comprising a rimary mixing chamber, an air chamber for supthrott e and air valve, said means comprischarge forming device for internal ing a fuel passage having an outlet com-L municating with the primary mixing chamber, and means communicating the air chamber suction to said fuel passage.

8. A charge "forming device-for internal combustion engines, comprising a primary mixing chamber, an air chamber for supply ing air to said primary mixing chamber under all operating conditions, and to said secondary mixing chamber under certain operating conditions, a valve for controlling the flow 0t air from said chamber to the secondary mixing chamber, a throttle for controlling the flow of primary mixture from the primary mixing chamber, means for operating said air valve by the throttle, and means making the static suction Within the air chamber the dominant factor controlling the supply of fuel to the primary mixing chamber during the entire 0 ening movement of said throttle and air valve, said means comprising a fuel passage having an outlet communicating With the primary mixing chamber, and means communicating the air chamber suction to said fuel passage.

9. A. charge forming device for internal combustion engines, comprisin a main housing, a. primary mixing chamber formed therein, an air chamber supplying air to said primary mixing chamber, a secondary mixing chamber into which thelprimary mixing chamber is adapted to deliver a primary mixture or fuel and air, and means making the static suction Within the air chamber the dominant factor controlling the supply of fuel to the primary mixing chamber, said means comprising a' fuel sup ly passage formed in the Wall of the main ousing provided With an outlet communicating with the primary mixing chamber, and an oritice communicating with the air chamber.

10. A charge forming device for internal combustion engines, comprising a main housing, a primary mixing chamber formed therein, an air chamber supplying air to said primary mixing chamber, a secondary mixing chamber into which the primary mixing chamber. is adapted to deliver a primary mixture of fuel and air, and, means making the static suction Within the air chamber the dominant factor controlling the supply of fuel to the primary mixing chamber, said means com rising a fuel supply passage formed in t e Wall of the main housing pro" vided With an outlet communicating with the.

primary mixing chamber, an orifice com= municating with the air chamber, and means shielding said orifice from the effect of impact of the air entering the air chamber.

ii. A charge forming device for internal combustion engines, comprisin a main housing, a primary mixing cham er formed therein, an air chamber supplying air to said primary mixing chamber, a secondary min ing chamber into which the primary mig lllll llli chamber is adapted to deliver a primary mixture of fuel and air, and means making the static suction within the air chamber the dominant factor controlling the supply of fuel to the primary mixing chamber, said means comprising a fuel supply passage formed in the wall'of the main housing providedwith an outlet communicating with the primary mixing chamber, an orifice communicating wit the air chamber, the axis of said orifice being normal to the path of air entering the air chamber whereby the orifice is not subject tothe effect of impact of the air entering the air chamber.

12. A charge forming device for internal combustion engines, comprising a main housing havin a plurality of prlmary mixing chambers ormed therein, a plurality of secondary mixing chambers into which the primary mixing. chambers are adapted to deliver a primary mixture of fuel and air, an

' air chamber supplying air to all of said primary mixing chambers, and means for making the static suction within the air. chamber the dominant factor controlling the supply of fuel to all of said primary mixing chamj lurality of bers,said' means comprising a fuel supply passages, each of w ichis provided with an outlet communicating with one of said primary mixture passages, and means .for communicating the air chamber suction to all of said fuel passages.

13. A charge forming device for internal combustion engines, comprising a main housing havin a. plurality of prlmary mixing chambers formed therein, a plurality of secondary mixing chambers into which the primary mixing chambers are adapted to de l1ver a primary mixture of fuel and air, an

bers, said means comprising a mary mixing chambers are adapted to deliver a primary mixture of fuel and air, an air chamber supplying air to all of said primary mixing chambers, and means for making the static suction within the air chamber ,the dominant factor. controlling the supply of fuel to all of said primary mixing chamlurality of fuel supply passages, each of w ich is provided with an outlet communicating with one of said primary mixing chambers, and an air inlet of larger size than said outlet, all of said air inlets communicating with said air chamber.

14. A charge forming device for internal liver a primary mixture of fuel and air, an I air chamber supplying air to all of said primary mixing chambers, and means for mak ing the static suction within the air chamber the dominant factor controlling the supply of fuel toall of said primary mixing chambers, said means comprisin a plurality of fuel suppl passages, each 0 Wl'llCh is adapted to supp y fuel to one of the primary mixing chambers, outlet passages of the same length connecting the fuel supply passages with the associated primary mixing chambers, air inlets for all of said fuel supply EZSSflgBS communicating with said air cham- 16. A charge forming device for internal combustlon engines, comprising a mam houschambers formed therein, a plurality of secondary mixing'chambers into which the pri- 'mary mixing chambers are adapted to deliver a primary mixture of fuel and air, an air chamber supplying air to all of said primary mixing c ambers, and means for making the static suction within the air chamber the dominant factor controlling the supply ing having a plurality of primary mixing of fuel to all of said primary mixing cham bers, said means comprising a plurality of fuel suppl passages, each of which is provided wit an'outlet communicating with one of said primary mixture passages, and means for communicating the air chamber suction to all of said fuel passages, and a common fuel canal supplying fuel to all of said fuel passages. I

In testlmony whereof I hereto aflix my signature.

' WILFORD H. TEETER.

combustion engines, comprisin a main housing having a plurality of primary mixing chambers formed therein, a plurality of secondary mixing chambers into which the pri 1 the dominant factor controlling the supply of fuel to all of said primary mixing chamea, fuel supply passages, each of bers, said means comprising a plurality of ch is .pro-