US1762463A - Charge-forming device - Google Patents

Description

June 10, 1930. F. E. ASELTINE ET AL CHARGE FORMING DEVICE Filed Sept. 22, 1927 4 Sheets-Sheet 1 June 10, 1930. s T ET AL CHARGE FORMING DEVICE Fi led Sept. 22, 1927 4 Sheets-Shee F. E. ASELTINE ET AL 1,762,463

CHARGE FORMING DEVICE Filed Sept. 22. 1927 4 Sheets-Sheet s June 10, 1930.

June 10, 1930. F. E. ASELTINE ET Al- CHARGE FORMING DEVICE Filed Sept. 22. 1927 4 Sheets-Sheet 4 attorney Patented June 10, 1930 HE STATES FRED E. ASELTINE AND WILEORD H. TEE'IER, OF DAYTON, OHIO, ASSIGNOBS, IBY MESNE ASSIGNMENTS, TO DELCO PRODUCTS CORPORATION, OF DAYTON, OHIO, A.

CORPORATION OF DELAWARE CHARGE-FORMING DEVICE Application filed September 22, 1927. Serial No. 221,370.

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 mixing chambers, one for each intake port of the engine, having a common source of fuel supply and cooperating respectively with a plurality of secondary mixing chambers each located adjacentan en- W gine intake port, each of said secondary mixing chambers receiving primary fuel mixture from one of the primary mixing chambers and receiving additional air through an air manifold which supplies air to all the secondary mixing chambers.

Examples of this type of charge forming device are disclosed in my prior copending applications, Serial No. 4,665, filed Jan. 26, 1925, Serial No. 54,592, filed Sept. 5, 1925, and Serial N 0. 83,97 9 filed J an. 26, 1926.

The general objects of the devices covered by the applications above referred to are, first, to provide a mixture of fuel and air having the desired fuel and air ratio under all operating conditions, and second, to deliver equal quantities of this mixture to each cylinder of the engine under varying conditions of load and speed, without requiring any heating of the fuel or fuel mixture before it is delivered to the engine intake.

The principal objects of this invention are to provide novel and improved mechanism for controlling the proportions of fuel and air in the fuel mixture and to provide improved means for securing more equal distribution of the mixture to the different engine intake ports.

lVith these objects in view one feature of the invention consists in the provision of an improved form of dash pot retarding the opening movement of the air valve, said dash pot comprising a movable cylinder, moved toward the dash pot piston during opening movement of the throttle valve.

further feature of the invention con sists in the provision ofa hollow operating shaft for operating the throttle valves, the hollow shaft acting as an equalizing pas sage, to equalize the pressure in the various secondary carburetors.

Another feature of the invention resides in the provision of a blow-off or relief valve on the dash pot piston which opens under certain conditions of operation to permit free operation of the piston and unretarded opening movement of the air valve.

A still further feature of the invention consists in the provision of an adjustable cam for operating the movable dash pot cylinder, to vary the movement of said cylinder on a given movement of the throttle shaft.

Another feature of the invention is the provision of a novel form of re-atomizing element situated in the outlets of the secondary carburetors to collect any liquid fuel flowing on the walls thereof and direct such fuel back into the ingoing mixture stream.

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 embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a plan view of a charge forming device for a six cylinder engine constituting a preferred form of this invention.

Fig. 2 is a side elevation, partly broken away to show certain parts in section.

Fig. 3 is a section on line 3-3 of Fig. 1, showing also a fragmentary sectional detail of the engine intake port.

Fig. 4; is a vertical section on line 44 of Fig. 2.

Fig. 5 is a vertical section on line 5--5 of Fig. 1.

Fig. 6 is a fragmentary section on enlarged scale on the line 66 of Fig. 2.

Fig. 7 is a horizontal section on line 77 of 2.

Fig. 8 is a section on the line 88 of Fig. 7.

Fig. 9 is a fragmentary section on line 99 of Fig. 1.

Fig. 10 is an enlarged detail sectional view of the valves in the fuel intake conduit.

Fig. 11 is a plan View of the distributor block.

Fig. 12 is a plan View of a plate mounted on top of the distributor block, having an equalizer passage formed therein.

Fig. 13 is a section on line 1313 of Fig. 11 and 12. V

Fig. 14 is a detail view of the throttleop crating lever.

Fig. 15 is a detail elevation of the operating connections for the dash pot cylinder.

Fig. 16 is a detail section on line 1616 of Fig. 5.

Fig. 17 is a detail vertical section through a modified form of distributor block showing one of the primary carburetors.

Similar reference numerals refer to similar parts throughout the several views.

The reference numeral 10 indicates the air manifold which is provided with three outlet branches 11, 12 and 13 having flanges as indicated in Fig. 1 for connection to the engine block. Each branch connects to an engineport which serves two adjacent cylinders. In Fig. 3 is shown a passage 14 leading from the intake port to one of the cylinders of such pair, the passage 14 being controlled by the engine intake valve 15.

The air manifold has secured to the lower side thereof, by screws 20, a frame 21 supporting a constant level fuel chamber 22, attached to said frame by screws 23. Cast integral with said frame and projecting therefrom is a conduit 25, through which fuel is led to said fuel chamber from a main source of fuel supply. The conduit 25 is formed with an enlarged chamber 26 in its outer end, in which a screen 27 is secured by a plug 28, which is adapted to be connected to the fuel line. The screen is so situated that all fuel entering the fuel chamber mustpass therethrough. To control the flow of fuel from conduit 25 to the fuel chamber there is provided a float 29 pivoted at 30 and operating in the usual manner to control a valve 31 which cooperates with a valve seat 32 to maintain a constant fuel level in the fuel chamber 22.

Secured by screws 40 to the upper side of the air manifold is'a distributor block 41, which has a plurality of primary mixing chambers formed therein, as indicated in Figs. 9 and 13. The construction of this distributor block and the means for conducting the primary fuel mixture therefrom to the secondary carburetors will be more specifically described hereinafter.

To conduct fuel from'the constant level chamber to the distributor block there is provided a tube 43 screwed into a passage 43 formed in the wall of the air manifold. The tube 43 extends downwardly into the fuel chamber to a point below the fuel level. A calibrated fuel metering plug 44 is secured in the lower end of said tube to control the flow of fuel thereto. The passage 43 connects the upper end of the tube 43 and the distributor block which is secured on the opposite side of the manifold wall immediately above the said tube as indicated in Fig. 9.

Received in the passage 43 is a sleeve 45 partly closed at its lower end and open at its upper end. A hole 46 is bored in the lower end of said sleeve to form a valve seat with which a suction V operated valve 47 cooperates. The valve is provided with a constantly open passage 48 therethrough having a constriction therein 49 to control the flow of fuel. At low speeds when the suction in the primary mixing chambers is slight and the fuel is flowing at low velocity, the valve 47 remains seated as shown in Fig. 10 and all of the fuel flows through the passage 48. On

higher speed when the suction and fuel velocity increase the valve 47 is lifted and fuel is permitted to flow around such valve.

Seated on top of the sleeve 45 is a check valve 50 which prevents fuel in the fuel conduit flowing back to the fuel chamber. It has been found that under certain conditions, as when the engine speed is suddenly reduced, the sudden reduction in suction on the vertical column of fuel between the primary mixing chambers and fuel chamber would permit this column to drop sufficiently to cause a temporary starving of the engine unless means were provided to prevent such occurrence. It is the function of the check valve to prevent the dropping of the column of fuel as described. The upward movement of the check valve is limited by fingers 51 projecting from a sheet metal collar 52 received in an enlarged portion of the passage 43*.

The lower face of the distributor block is formed with a groove 53 therein, which constitutes a fuel distributing canal to conduct liquid fuel from the passage 43 to each primary mixing chamber as indicated in Fig. 9. A removable fuel metering plug 54 leads fuel from the canal to each of the primary mixing passages 42. An air inlet bushing 55admits air to each of the primary mixing chambers adjacent the fuel metering plugs 54.

The inner end 56 of each of the bushings 55 is somewhat reduced in external diameter, as shown in Fig. 13, toprovide a space between said reduced portion and the wall of the mixing chamber. The reduced end 56 projects above the outlet of the fuel metering plug, the fuel flowing from the mea -L63 pluginto the space between the part 5.6 and the wall of the mixing chamber. The end portion 56 is cut off at an angle to the ver .ticlal. construction of air and fuel jets prevents the ingoing stream of air passing directly over the fuel jet, forms a small deadairspace into which the fuel is delivered, prevents the formation of eddy currents at the fueljets and at low speeds eliminates the effect of dynamic suction or velocity head on said jets. In this way a fuel mixture substantially uniform in proportions of air and fuel is formed in the primary mixing chambers at low speed. This mixture is, however, super rich in fuel content and is diluted with additional air in the secondary mixing chambers in a manner more fully set forth hereinafter.

To secure equalization of pressure in the various primary mixing chambers a passage 57 is provided to place all of said chambers in communication with each pther. The passage 57 is a groove or channel cut in the bottom face of a plate 58 secured in any suitable manner to the upper side of the distributor block. The passage 57 communicates with each primary mixing chamber through holes 59 bored in the top of said distributor block.

Each primary mixing chamber is connected with one of the branches of the main air manifold by means of a conduit, through which the super rich primary mixture is drawn by engine suction. The conduits connecting the primary mixing chambers with the branches 11 and 13 of the air manifold comprise pipes 60 and (31 respectively. One end of each of these pipes is received in an enlarged recess 62 in the distributor block, such recess forming the outlet of a primary mixing chamber. The other end of each of said pipes is received in an elbow 63 secured on top of the air manifold. Each of said elbows has a passage St therein which registers with a pas sage 65 formed in the manifold wall. The primary mixing chamber which communicates with the branch 12 of the air manifold is connected therewith by a vertical bore 67 formed in the distributor block which registers with a bore 68 in the wall of manifold branch 12.

The construction of each of the secondary corburetors is identical and that which is located in branch 13 of the manifold is shown in Fig. 3. A large Venturi tube 70 is mounted in said branch 13 and is held in position against a ledge 71 therein by a set screw 72, the tapered end of which cooperates with a recess 73 in the venturi. The venturi is provided with a channel 74: in its outer wall which registers with the outlet 65 of the rich mixture conduit, and a slot 75' in the wall of said venturi at the point of greatest depression therein permits pasthe flow of the resultant mixture to the associated intake port is controlled by a throttle valve 76, fixed on a rotatable hollow shaft 77. The secondary air flowing through the Venturi tube creates a depression at the slot 75 which causes air to flow into the primary mixing chamber and draws the rich primary mixture through the conduit connecting the primary and secondary mixing chambers into the latter. Each outlet branch of the manifold is pro vided with a Venturi tube 70 and throttle 76, the throttles being simultaneously operated by mechanism hereinafter more fully described.

At small openings of the throttles 76 there is only a small quantity of air flowing through each manifold branch at relatively low velocity. Because of the low velocity of air flow there is a tendency for fuel par ticlcs to settle out of the fuel mixture and collect on the manifold walls, giving rise to uneven fuel distribution. To avoid this tendency each branch of the manifold is provided with an automatic restricting valve which opens in accordance with the velocity of the entering air and causes the fuel mixture to pass said value at relatively high velocity under all operating conditions. Each of such valves is mounted in a sleeve 78 inserted in the outlet of the manifold branch and extending into passage 14. The sleeve 7 8 is held in place by means of cars 7 9 cut out of the wall of said sleeve and bent outwardly therefrom, said ears being clamped between the manifold and engine when the manifold is attached thereto. The sleeve 78 is provided with a transverse pin 80 on which two flap valves 81 are pivoted. These valves are urged toward closed position by a spring 82 which is connected to said valves as illustrated in Fig. 3. As the velocity through the sleeve increases these flap valves are opened against the pressure of said spring. The lower wall of said sleeveis provided with a projecting lip 83 which is bent back into the sleeve as shown in Fig. 3, forming a space between said lip and the lower wall of the sleeve. The lower flap valve 81 normally rests on the upper surface of said lip. Holes 8% connect the intake passage 14: with the space between said lip and the sleeve and permit the passage of fuel mixture for idling when the flap valves 81 are closed. These holes serve also to cause any fuel which does precipitate from the fuel mixture to flow back into the mixture stream to be re-atomized. A similar sleeve and flap valve assembly is inserted in the manifold branches 11 and 12.

To effect simultaneous operation of the three throttles 76 in manifold branches 11, 12 and 13 the throttle in branch 12 is fixed on a hollow shaft rotatably mounted in the wall of said branch and aligned with shafts 77 on which the throttles in branches 11 and 13 are mounted. The shaft 85 is operated by a lever 86 secured thereto in any suitable manner, and operated by any desirable form of operating connection ex tending to the steering column or other point convenient to the operator. Lever 86 has a projecting end 87 which abuts against a stop screw 88, adjustable in a projecting lug formed on the manifold casting. Adjustment of the screw 88 will limit the closing movement of the throttles. The shafts 77 are connected to the shaft 85 to be moved thereby. The means for connecting said shafts together comprises a sleeve 89 secured on each end of shaft 85 by means of a split clamp as shown in Fig. 1. The end of eachshaft 77 is also received in the bore through sleeve 89, and fits within the bore loosely enough to move therein and compensate for expansion due to heat, the end of each shaft 77 being normally slightly spaced from the end of shaft 85 topermit this movement. An arm 90 extending from each sleeve 89 has a pin 91 projecting therefrom, said pin being received in a slot formed in the end of an arm 92 secured on each shaft 77 by a split clamp. Obviously as the shaft 85 is actuated the pins 91 engaging arms 92 move the shaft 77 through exactly the same distance as the shaft 85 is moved. By releasing the split clamps securing sleeves 89 and arms 92 in position, the shafts 77 and 85 may be moved relatively to each other, to secure exact alignment of the throttles 75.

To admit air to the air manifold there is provided an air inlet horn 93 secured by screws 94 to the upper wall of the manifold casting, over a hole 95 in said wall, admitting air to the interior of the manifold. Flow of air through the air inlet horn is controlled by a valve 96, normally held against its seat 97 by a spring 98. The air valve is mounted on a stem 99, received in a guiding sleeve 100, the upper end of which limits the opening movement of said valve. The guide sleeve is supported by a spider, an arm 101 of which is shown in Fig. 4. The arms of the spider are secured to the air horn by screws 102. The bottom wall 103 of the manifold has a hole 104 formed therein to facilitate assembly of the parts. This hole is closed when the device is assembled by a packing washer 105 secured to a metal plate 106 fixed on the lower end of the guide sleeve 100.

To start the engine the air valve is held against its seat to prevent admission of auxiliary air to dilute the super rich primary mixture. To effect this operation of the air valve a sleeve 107 is provided, slidably mounted on the guide sleeve 100. This sleeve has an enlarged flange 108 at its lower end, a groove 109 being formed in the upper face of the said flange, and providing a seat for the lower end of the air valve spring. The sleeve 107 is lifted to bring the upper end of the said sleeve into engagement with the air valve, to prevent opening thereof, by means of a bifurcated lever 110 pivotally mounted in the wall of the air horn, as shown in Fig. 2. The arms of said lever have pins projecting inwardly therefrom and engaging in a groove 111., formed in the periphery of the flange 108. The lever 110 is fixed to an operating shaft having an operating arm 112, to which is secured in a hole 113 a suitable operating connection extending to some convenient point adjacent the operator. The sleeve may be adjusted to regulate the tension of the air valve spring, by means of a set screw 114 which engages lever 112, to regulate the normal position of the sleeve.

To provide for enrichment of the fuel mixture on acceleration, and to prevent fluttering of the air valve on sudden openings of the throttle the opening of the air valve is retarded by a liquid dash pot, as shown in Figs. 4 and 6. This dash pot comprises a cylinder 115 slidably received in a guide sleeve 116 east integral with and projectin downwardly from the frame 21. Holes 117 and 118 are provided in the guide and cylinder respectively, below the fuel level in the float chamber, said holes registering with each other when the cylinder is in its normal lowered position to permit passage of liquid fuel from the float chamber to the interior of the dash pot. The cylinder is lifted for a purpose and by means hereinafter more fully described.

Cooperating with the cylinder is a piston 119, slidable on a piston rod 120 secured to the lower end of the air valve stem 99. Thepiston rod is provided with a projecting flange 121 against which the piston is normally held by a spring lying between the piston and a collar 123 adjustably mounted on the piston rod, so that by adjustment of said collar the spring pressure may be regulated. The piston and the flange 121 are provided with holes 124 and 125 which permit the passage of fuel through the flange and piston under certain conditions of operation. The flange 121 is provided with an upwardly projecting annular rim 126 forming a seat for the piston which acts as a valve cooperating therewith as hereinafter described. A check valve 127 is provided to control flow through holes 125, said valve being mounted on the piston rod 120 between the flange and a collar 128, spaced to permit limited movement of the valve. A 5 pass 129 comprising a pipe secured in tile wall of the cylinder has its upper end normally covered by the dash pot piston but is uncovered during downward motion of said piston to permit passage of fuel from the lower end of the cylinder, around the piston, and relieve the retarding action of the dash pot when the air valve is partly open.

The function of the dash pot will now be described. hen the throttle is opened on low or intermediate speeds for acceleration, the manifold suction is communicated to the lower side of the air valve. This suction is, however, insufficient to cause sufficient pressure against the piston to collapse the spring 122 and the piston is held in contact with the flange 121, during its downward movement, preventing passage of fuel throughholes 124, and enabling the dash pot to retard the openingmovement of the air valve, the check valve also closing ports 125 at this time.

The retarding of the air valve opening gradually diminishes as the by-pass 129 is being uncovered to allow the air valve to open more rapidly and supply air to the engine to give the required power as the fuel flow and engine speed increase. The relation of the by-passto the piston determines the duration of retardation of the valve movement and this relation is varied automatically according to the posi tion of the throttles. The greater the initial opening of the throttles at the time they are suddenly opened further to accelerate, the less will be the retarding action. This variation is necessary because less retarding of the air valve would be required when accelerating from a to a mile per hour speed than from a 10 to 25 mile per hour speed,'assumingthat the grade of the road is substantially the same.

Under certain operating conditions where there is a very sudden increase in depres sion below the air valve it is not desirable to retard the opening movement of said valve.

As an example of such operating conditions, suppose the vehicle is coasting at a speed of 40 miles per hour with the clutch engaged and the engine turning at a speed correspondingto the vehicular speed, with the throttles closed. If the throttles are opened on reaching a level road or up grade ,opened. This vacuum is great enough to pull the air valve downwardly with enough force to build up a great enough pressure in the dash pot to collapse the spring 122, whereupon the piston 119 will be lifted from the flange 121, permitting escape of the liquid through holes 124: in the piston, and

allowing the air valve to move freely to its open position. As soon as the piston is separated from the flange it will remain separated until the pressure is relieved, when the air valve reaches the end of its opening movement.

To additionally retard the opening movement of the air valve means are provided to lift the dash pot cylinder as the throttles are opened. Such means comprises a bifurcated lever 130 fixed on a rock shaft 131 rotatably mounted in the frame 21. The two arms of the lever 130 are provided with projecting pins 132 engaging beneath a flange 133 formed at the upper end of the cylinder. To actuate the rock shaft and lift the cylinder a lever 13a is fixed on the end of said shaft outside the carburetor casing, as shown in Fig. 5. A lever 135 is pivoted on the rock shaft 131, and is provided at its free end with a roller 137 engaging in a cam slot 138 formed in an arm 139 pivoted at 1&0 on the end of an operating lever 141 adjustably secured by means of a split clamp 142 on the throttle shaft 85. Means are provided for adjusting arm 139 on its pivot to vary the throw of the arm 135 to regulate the distance through which the cylinder 119 is lifted on any given movement of the throttle. Said means consists of an adjusting screw 143 threaded in arm 144C projecting from lever 1 11, and held in adjusted position by a spring detent 1 .5. The screw has a reduced lower end 146 which projects through a hole in a bent over portion M7 of the arm 139, a spring 14:8, being provided between the part 147' and a collar 149 secured on the lower end of screw 143, to hold the bent over portion 147 against a shoulder formed by the enlarged threaded portion of the screw. To enable the arm 135 to move rock shaft 131, said arm is provided with a lug 149 having a screw 150 threaded therein. The lower end of the screw is reduced in diameter, as shown in Figs. 5 and15, and extends through a hole in the lever arm 13%. A spring 151 surrounds the reduced portion of the screw between a collar 152 slidably mounted thereon and the lever 134, the spring acting to normally hold the lever against a nut 153 on the screw 150 below said lever. On clockwise movement of the lever 141 the cam depresses the arm 135 and through the medium of spring 151 rocks the lever 1,34 clockwise to lift the dash pot cylinder, if the opposition to movement thereof is not greater than the tension of the spring. In the latter event the spring willcollapse without moving said cylinder.

One reasonfor moving the dash pot cylinder in the manner described is because it is found that when the throttles are opened slowly the downward movement of the dash pot piston is slow and there is sufficient leakage of fuel past the piston to largely eliminate the retarding effect of the dash pot on opening movement of the air valve. When the cylinder is moved upwardly as the piston descends, however, it tends to displace more fuel than can escape by leakage and retards the opening movement of the air valve as desired.

A further reason for moving the dash pot cylinder is to control the degree of movement of the dash pot piston before the bypass 129 becomes effective, and thus control the duration of the retarding effect on the air valve movement. For instance on acceleration at low speeds it is desirable to provide an enriched mixture for a longer period of time than on acceleration at higher speed. This result is brought about by adjustment of the cam arm 189. If the cam arm is moved downwardly by the adjusting screw 143, the cylinder is lifted so that with the parts at rest the upper end of the by pass is nearer to the top of piston 119, than if the adjusting screw is so set that the arm 139 is in raised position. It will be obvious therefore that with the cam arm adjusted in its lowered position the dash pot piston does not have to move as far to uncover the bypass, and the dash pot is therefore effective to retard the opening movement of the air valve for a shorter time, than if the arm 139 is in raised position.

Moreover, the adjustment of the cam arm not only changes the initial position of the dash pot cylinder, but also changes the speed at which said cylinder moves when the throttle is actuated. The lowering of the cam arm makes the cam slot 188 more nearly concentric to the shaft so that the cylinder is moved more slowly when the cam arm is in such position. The cylinder during such slower movement does not displace fuel .below the piston as rapidly as when the cylinder moves fast. Therefore, the cylinder is not as effective when moving slowly to offset the escape of fuel by leakage past the piston, thus reducing the retarding effect of the dash pot. I

It will be observed on inspection of Fig. 5, that adjustment of the cam arm does not change the distance between shaft 85 and the end of the camslot adjacent the pivot 140. It is clear therefore the position of the cylinder at the beginning of its movement may be changed by adjustment of the cam arm, with a resulting change in the distance through which the cylinder moves, but the position of the cylinder is unaltered at the end of its movement by any adjustment of said cam arm. 7

The upper end of the cylinder has seated thereon a closure element 160 having a hole 161 therein through which the valve stem 99 passes. The closure element is held in place on the cylinder by a spring 162, the upper end of which is received in a depression 163 formed in the packing washer 105.

A resilient operating connection for the dash pot cylinder is provided because of the inertia of the parts to be moved. Too sudden movement of the operating arm 134 might cause undue strains on these parts, therefore the operating arm is moved gradually through a spring.

In Fig. 17 is shown a modified form of distributor block having a different construction of primary mixing chamber. In this modification the passage 42 has'an enlarged chamber 200 in which a small Venturi tube 201 is received, said Venturi tube having projecting flanges 202 thereon which fit closely within the chamber 200. The Venturi tube is held in position by a hollow plug 203 screwed into the end of passage 42. Gaskets 204 are provided to prevent leakage of fuel around the outside of the Venturi tube. The fuel metering plug 54, connects the fuel canal 53, with a channel 205, provided between the flanges 202, the outer wall of the venturi and the wall of chamber 200. A plurality of fuel inlets 206 permit passage of fuel from the channel 205 to the interior of the Venturi tubes, the throat of which has an abrupt enlargement at the point where the inlets 206 pierce the wall. Primary air enters the plug 203 and flows past the inlets 206 at high velocity, creating so high a suction at the metering plugs 54,

that plugs having a smaller fuel feeding orifice may be employed with this form of distributor block than with the form shown in Fig. 13. The purpose of the enlargement at the inlets 206 is to compensate for expansion due to vaporization of fuel as it enters the Venturi tube.

Means are provided to establish communication between the interior of the hollow throttle operating shaft and each branch of the manifold to equalize the pressure in the several branches. To this end the throttle valves 76 are received in slots 210 in the throttle operating shaft, being held in position therein by screws 211 as shown in Figs. 3 and 4. Holes 212 and 213 are formed in the wall of the shaft on opposite sides of each throttle valve connecting the interior of the shaft with the space within the manifold. The construction is identical in the several manifold branches.

While the form of embodiment 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.

lVhat is claimed is as follows:

1. A charge forming device for an internal combustion engine having a plurality of intake ports, comprising a main air manifold having branches communicating with said intake ports, a primary carburetor having fuel and air inlets to form a primary fuel mixture, means for conveying such mixture to the branches of said air manifold, means for controlling the flow of fluid from the branches of said manifold and a sin le means for 0 eratin said controlliru a: z:

means and equalizing the branches of the manifold.

2. A charge forming device for an internal combustion engine having a plurality of intake ports, comprising a main air manifold having branches communicating with said intake ports, a primary carburetor havingfuel and air inlets to form a primary fuel anixture, means for conveying such mixture to the branches of said air manifold, a plurality of throttles for controlling the flow of fluid from the branches of said manifold, and a single means for operating the throttles simultaneously and equalizing the pressure in the manifold branches.

3. A charge forming device for an internal combustion engine having a plurality ofintake ports, comprising a main air manifold having branches communicating with said intake ports, a primarycarburetor having fuel and air inlets to form a primary fuel mixture, means for conveying such mixture to the branches of said air manifold, a hollow shaft communicating with all of the manifold branches for equalizing the pressure therein, and means operated by the shaft for controlling the flow of fluid through the manifold branches.

4. A charge forming device for an internal combustion engine having a plurality of intake ports, comprising a main air manifold having branches communicating with said intake ports, a primary carburetor having fuel and air inlets to form a primary fuel mixture, means for conveying such mixture to the branches of said air mani fold, a plurality of throttles for controlling theflow of fluid through the branches of the manifold, a hollow shaft for operating said throttles and communicating with all of the manifold branches to equalize the pressure therein.

5. A charge forming device for an internal combustion engine having a plurality l of intake ports, comprising a main a1r manifold having branches communicating with said intake ports, a primary carburetor having fuel and air inlets to form a primary fuel mixture means for conveying such mixture to the branches of said air manifold, a plurality of throttles for controlling the flow of fluid through the manifold branches, a hollow operating shaft for said throttles, said shaft being composed of a plurality of separate sections and means for securing said sections together so as to permit relative movement therebetween to compensate for expansion and contraction.

6. A charge forming device for an internal combustion engine, having a mixing chamber, fuel and air inlets therefor, a throttle valve, a valve controlling the admission of air and means for retarding the opening movement of the air valve comprising a dash pot having a movable piston, a movable cylinder, and means operated by the throttle for moving the cylinder.

7. A charge forming device for an internal combustion engine having a mixing chamber, fuel and air inlets therefor to form a fuel mixture therein, means for retarding the inflow of air on opening of the throttle, to increase the mixing chamber suction and form a rich mixture for acceleration, said means comprising a dash pot having a movable cylinder and means for moving said cylinder as the throttle is opened.

8. A charge forming device for an internal combustion engine having a mixing chamber, fuel and air inlets therefor to form a fuel mixture therein, means for retarding the inflow of air on opening of the throttle, to increase the mixing chamber suction and form a rich mixture for acceleration, said means comprising a dash pot having a movable cylinder, a shaft for operating the throt tle and an arm on the throttle shaft for operating said cylinder.

9. A charge forming device for an internal combustion engine having a mixing chamber, fuel and air inlets therefor to form a fuel mixture therein, means for retarding the inflow of air on opening of the throttle, to increase the mixing chamber suction and form a rich mixture for acceleration, said means comprising a dash pot having a movable cylinder, means for moving said cylinder as the throttle is opened and means for varying the retarding eflectof the dash pot comprising a fluid channel lay-passing the dash pot piston when the piston and cylinder occupy a certain position relative to each other,

10. A charge forming device for internal combustion engines having a throttle, a mix ing chamber, means for admitting fuel and air thereto to form a fuel mixture, an air inlet, a valve therein, means to retard the opening movement of said valve to provide a rich mixture for acceleration, comprising a dash pot having a piston secured to the air valve stem and a cylinder movable by the throttle, a by-pass in the cylinder for relieving the retarding effect of the dash pot, and means for varying the initial position of the cylinder relative to the piston to regulate the movement of the piston before the by-pass becomes effective.

a of the dash pot.

12. A charge forming device for internal combustion engines having a throttle, a mixing chamber, means for admitting fuel and air thereto to form a fuel mixture, an air inlet, a valve therein, means to retard the opening movement of said valve to provide a rich mixture for acceleration, comprising a dash pot having a piston secured to the air valve stem and a cylinder movable by the throttle, and means for varying the initial position of the cylinder relative to the piston to vary the duration of the retarding effect of the dash pot, said means comprising an arm for operating said cylinder, and an adjustable cam engaging said arm.

13. A charge forming device for internal combustion engines having a throttle, a mixing chamber, means for admitting fuel and air thereto to form a fuel mixture, an air inlet, a valve therein, means to retard the opening movement of said valve to provide a rich mixture for acceleration, comprising a dash pot having a piston secured to the air valve stem and a movable cylinder, and means for operating said cylinder comprising a throttle operating shaft, and a resilient operating connection between the shaft and the dash pot cylinder.

til

14. A charge forming device for internal combustion engines having a throttle, a mixing chamber, means for admitting fuel and air thereto to form a fuel mixture, an air inlet, a valve therein, means to retard the opening movement of said valve to provide a rich mixture for acceleration, comprising a dash pot having a piston secured to the air valve stem and a movable cylinder, means for moving said cylinder comprising a throttle operating shaft, a cam operated thereby, and a lever for operating said cylinder engaging said cam.

15. A charge forming device for internal combustion engines having a throttle, a mixing chamber, means for admitting fuel and 'air thereto to form a fuel mixture, an air inlet, a valve therein, means to retard the opening movement of said valve to provide a rich mixture for acceleration, comprising 'a dash pot having a piston secured to the air valve stem and a movable cylinder, means for movlng sald cylinder comprisin a throttle operating shaft, a cam operate thereby, a lever for operating said cylinder engaging said cam, and a resilient operating connection between the lever and said cylinder.

16. In a charge forming device for an internal combustion engine having a plurality of intake ports, an air manifold having a branch for each intake port and a common main air inlet, a suction opened air valve in said inlet, a dashpot for damping the opening of said air valve, said dashpot comprising a piston and a cylinder, a throttle valve on the engine side of said air valve, means for moving the dashpot cylinder to urge said air valve toward closed position upon the opening of said throttle, and a blow-off valve for limiting the maximum pressure obtainable in said dashpot.

17. A charge forming device for internal combustion engines having a mixing chamber, means for admitting fuel and air thereto, an air inlet valve, means for controlling the movement of said valve comprising a dashpot having a piston provided with a relief valve, said valve including a flange having a projecting rib thereon on which the dashpot piston normally seats. 18. A charge forming device for internal combustion engines having a mixing chamber, means for admitting fuel and air thereto, an air inlet valve, means for controlling the movement of said valve comprising a dashpot having a piston loose on the air valve stem, a flange projecting from the valve stem, a rib formed on said flange, and resilient means normally holding the piston seated on said rib, but permitting the piston to be lifted from the rib by excessive pressure in the dashpot.

19. In a charge forming device for an internal combustion engine, a plurality of primary carburetors, a single fuel passage leading fuel to all of said carburetors, each primary carburetor comprising an air intake passage, a Venturi tube therein, a fuel inlet in the wall of said Venturi tube, a metering plug connecting the fuel passage and said fuel inlet and an enlargement in the Wall of the Venturi tube adjacent said fuel inlet.

20. A charge forming device for internal combusion engines having a plurality of intake ports, comprising a manifold having branches communicating with said ports, means for supplying a primary mixture of fuel and air to said manifold, a plurality of throttles in said manifold branches to regulate the fiow therethrough, a hollow operating shaftfor operating all of said throttle valves and communicating with all of the manifold branches to equalize the pressure therein, an automatic air valve for supplying air to said manifold, and means operated by said hollow shaft for controlling the operation of said air valve.

21. A charge forming device for internal combusion engines having a plurality of intake ports, comprising a manifold having branches communicating with said ports, means for supplying a primary mixture of fuel and air to said manifold, a plurality of throttles in said manifold branches to regulate the flow therethrough, a hollow operating shaft for operating all of said throttle valves and communicating with all of the manifold branches to equalize the pressure therein, a suction operated air valve for supplying air to said manifold, a dashpot for resisting the opening movement of said valve, and means operated by said hollow shaft for controlling the resistance of the dashpot.

22. A charge forming device for internal combusion engines having a plurality of intake ports, comprising a manifold having branches communicatlng with said ports,

means for supplying a primary mixture of fuel and air to said manifold, a plurality of throttles in said manifold branches to regulate the flow therethrough, a hollow operating shaft for operating all of said throttle valves and communicating with all of the manifold branches to equalize the pressure therein, a suction operated air valve for supplying air to said manifold, a dashpot for resisting the opening movement of said valve, and means operated by said hollow shaft on opening movement of the throttle y for increasing the resistance of the dashpot.

23. A charge forming device for internal combusion engines having a plurality of intake ports, comprising a manifold having branches communicating with said ports, means for supplying a primary mixture of fuel and air to said manifold, a plurality of throttles in said manifold branches to regulate the flow therethrough, a hollow operating shaft for operating all of said throttle valves and communicating with all of the manifold branches to equalize the pressure therein, a suction operated air valve for supplying air to said manifold, a dashpot for resisting the opening of the air valve, comprising a piston secured to the valve and a movable cylinder, and means operated by said hollow shaft for moving said cylinder to regulate the effectiveness of the dashpot.

24. A charge forming device for internal combusion engines having a plurality of in take ports, comprising a manifold having branches communicating with said ports, means for supplying a primary mixture of fuel and air to said manifold, a plurality of throttles in said manifold branches to regulate the flow therethrough, a hollow operating shaft for operating all of said throttle valves and communicating with all of the manifold branches to equalize the pressure therein, a suction operated air valve for supplying air to said manifold, a dashpot for resisting the opening of the air valve, comprising a piston operated by the valve and a movable cylinder, and means operated by said hollow shaft on opening movement of the throttles for moving said cylinder to increase the resistance of said dashpot.

In testimony whereof we hereto affix our signatures.

FRED E. ASELTINE. WILFORD H. TEE'IER.

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