US1913144A - Charge forming device - Google Patents

Description

June 6, 1933. w, H TEETER 1,913,144

CHARGE FORMING DEVI CE June 6, 1933. w. H. TEETr-:R

CHARGE FORMING DEVICE Filed July 18, 1928 4 Sheets-Sheet 2 4 Sheets-Sheet 3 w. H. TEETER CHARGE FORMING DEVICE Filed July 18, 192s June 6, 1933.

June 6, 1933, w. H. TEETER CHARGE FORMING DEVICE Filed July 18, 1928 4 Sheets-Sheet 4 NNY.

Patented June 6, 1933 UNITED lSTATES PATENT OFFICE ASSIGNOR BY IEGN'E ABBIGNHENTS, TO

oN, omo, A coaromazon or DELAWARE A CHARGE FORHING DEVICE Application illed July 18, 1928. Serial I0. 298,665.

. This invention relates to charge formin devices for internal combustion engines an more particularly to that type of charge forming device which comprises a plurality of primary carburetors each of which supplies a primary mixture of fuel and air to one of a plurality of secondary mixing chambers, in which the primary mixture may be mixed with additional air under certain operating conditions.

Examples of such charge forming devices are disclosed in my copending application 221,372 filed Sept. 22, 1927, and those of .i Fred E. Aseltine et al. 221,371 randv288,683 15 filed Sept. 22, 1927 and June 10, 1928 respectively.

It is the primary object of this invention -to provide means for accurately controlling the mixture proportions during certain op- .'erating conditions, and more particularly to provide means for forming a mixture of the correct proportions during the acceleration period to give the necessary power for smooth and rapid acceleration.

Briefly this object is accomplished by the provision of an air throttle controlling the admission of secgndary air to the secondary mixing chambers, which is opened by the primary throttle, but which is so constructed that its opening is temporarily delayed relative to the primary throttle on all opening movements of the latter, whereby the admission o secondary air is restricted to some l extent during the acceleration period.

35 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 present invention is clearly shown. i

In the drawings:

Fig. 1 is a plan view of the present invention attached to the engine cylinder head, a part of which is shown in section.

Fig. 2 is a side elevation looking toward the engine block.

Fig. 3 is a section on line 3-3 of Fig. 1. Fig. 4 is a section on line 4-4 of Fi 1. Fig. 5 is a fragmentary detail-section on 5 the line 5- 5 of Fig. 3.

. mixing chamber on the line Fig. 6 is a detail view of the primary throttle valve.

Fig. 7 is a'side elevation of the main carburetor unit looking from the right in Fig. 2.

Fig. 8 is a side elevation of the main car- 55 buretor unit looking from the left in Fig. 2.

Fig. 9 is an enlarged detail section, with certain parts omitted, showing the secondary air valve and dash pot resisting its openin Fig. 10 is a detail elevation of the lin connecting the throttle and secondary air valve.

Figs. 11 and 12 are detail sections at right angles to each other of the float valve mechanism and fuel inlet passage controlled thereby. i

Fig.. 13 is a section through the secondary 13-13 of Fig. 2.

Fig. 14 is a detail section on line 14-14 of Fig. 3.

It will be observed that the main air passage which admits air to the secondary mixing chambers has in some instances in this specification been termed a secondary air passage, while the air flowing through such passage has been termed secondary air. These terms have been used to distinguish from the primary air passage and primary air which goes to the primary mixing chambers.

The device disclosed herein comprises a main air manifold indicated in its entirety by the reference character 10, and having three outlet branches 11, 12 and 13 each of which is adapted to communicate with one of the ports 14 of a multi-cylinder engine. Each port serves two adjacent cylinders through valve ports 14a and 145, as clearly indicated in Fig.I I. The cylinder head is shown in three separate fragments 15, but it will be understood that it may be an integral structure. The branches 11, 12 and 13 are each provided with an attaching flange 16, for attaching the manifold to the engine blocli in the conventional manner. Ad'acent the inlet of the manifold is provide a flange 17 to which may be secured the main carbu'ltor unit as shown in Fig. 3.

e main carburetor unit comprises a main` housing in the form of a single casting 18, 100

attached by screws 19 to the flange 17. An air inlet horn 20, the flow of arr throu h which is regulated in a manner later' escribed, is secured in pos1t1on over an opening in the up )er wall of said housing by screws 22 which pass through flanges 23 and 24 on the horn and housing respectively. A casting 25 having certain dashpot chambers and fuel passages, described in deta1l hereinafter, formed therein is secured by screws 26 to the lower wall of the main housing 18, a gasket bein provided between the castings to make a tig t joint, and a sheet metal fuel bowl 27 is held tight against av shoulder 28 on said main housing 18 by means of a screw 29 which is screwed into a post 30 depending from and integral with the casting 25.

A fuel line leading to a main source of fuel supply (not shown) is connected to a nipple 31, screwed into the main housing 18 as shown in Fig. 1. This nipple may have a screen secured therein in a manner well known so that incoming fuel must pass through the screen and said nipple communicates with a bore 32 formed in the Wall of housing 18, the bore 32 connecting with bore 33 also in the wall of said housing as shown in Fig. 12. At its inner end the bore 33 connects with a vertical bore 34, which in turn communicates with a bore 35 in casting 25. A plug 36 is screwed into the lower end of bore 35 and is provided with lateral fuel outlets 37 through which the fuel flows into the float chamber. Cooperating with valve seat 38 is a valve 39 controlled by a float 40 pivoted at 41. The valve operates in the usual manner to maintain a constant fuel level in the said float chamber@ Fuel is conducted from the fuel bowl to a plurality of primary fuel nozzles 42 located in the primary mixing chambers 43 formed in the central part of the main housing which may be termed the distributor block. The construction of the distributor block and cooperating elements comprising the primary carburetors will be more fully described hereinafter. To permit the fuel to flow from the fuel bowl to the primary nozzles 42 the casting 25 is provided with a vertical fuel channel 44 which communicates at its upper end with a horizontal fuel canal 45 which connects with each of the nozzles 42 through holes 46. Fuel is admitted from the fuel bowl to the channel 44 at low speed through a metering orifice 47. All of the fuel flowing to the fuel nozzles 42v up to a certain predetermined engine speed, for example that corresponding to a vehicular speed of 20 miles per hour passes through the metering orifice47. For higher speeds than said predetermined speed, fuel is also admitted to the fueluchannel 44 through an orifice ,48 controlled by a fuel valve 49, operated in a manner fully described hereinafter, and thence throu h a horizontal channel 50, connecting With t ie lower end of channel 44.

Fuel is lifted from the fuel bowl through the nozzles 42 to the primary mixing chambers by the suction therein. When the throttle is moved toward closed position to reduce the engine speed there is a sudden reduction in suction on the vertical column of fuel between the fuel bowl and the nozzle which might permit this column of fuel to drop sufliciently to cause a temporary fuel starving of the engine unless means were provided to prevent t e dropping of such column of fuel. To prevent this action a check valve 51 is received in an enlarged chamber 52 at the junction of channels 44 and 45 and on reduction of suction in the primary mixing chambers seats on the bottom of such chamber, preventing downward flow through the channel 44.

The metering orifice 47 is drilled in the casting 25 and the drill hole on the opposite side of thechannel 44 is plugged by a screw 53.

'Each primary fuel nozzle is shown herein as provided with a main fuel outlet in the top of the nozzle and a secondary fuel outlet comprising two holes 54 and 55 formed in the vertical Wall of the nozzle and diametrically opposite each other as shown in Fig. 3. At higher speeds there is sufficient suction in the primary mixing chambers to cause fuel to flow from the main fuel outlet in the top of each primary nozzle, as well as from the holes 54 and 55. At idle or very low speed, however, there is insuflicient suction t'o cause such a flow of fuel, the fuel at such time standing in the nozzle at a point between the top of the nozzle and the orifices 54 and 55, flowing from such orifices by action of gravity. Each fuel nozzle is provided with a restricted fuel metering orifice 56.

In the carburetor disclosed herein the central portion of the main casting constitutes the distributor block and is indicated at 60 in Fig. 3. The distributor block has three primary mixture passages 61, 62y and 63 formed therein, such passages being parallel to each other and close together as indicated in Fig. 5. These passages extend straight through the block, and register with other passages formed in the adjacent wall of the manifold. The middle one of these passages in the manifold wall is in alignment with the mixture passage 62 and receives a tube 70 as shown in Fig. 3 while the other two pas\ sages in the manifold wall are L-shaped and communicate with the primary mixture pipes 71 and 72 as fully shown and described in copending application, Serial No. 288,683. The inlet ends of the primary mixture passages Where the nozzles project into such passages are of larger diameter than the outlet ends thereof and between the inlet and outletend of each passage its cross-sectional area is constricted as indicated at 64, such constriction reducing the velocity of the5 air current passing the nozzle.

j The flow of primary mixture through the passages 61, 62 and 63 is controlled by a single throttle valve 65 which extends across all of the primary mixture passages, and has grooves 66 therein which register with the said passages 61, 62 and 63. This throttle valve has spindles 67 projecting from each end and is rotatably mounted in the Walls of housing 18. A groove 68 is provided in the throttle which cooperates with the inner end of a screw 69, adjustable in the casting, to prevent longitudinal movement of the said throttle.

The tube 70 conveys the primary mixture from the passage 62 to a secondary mixing chamber formed in the middle branch 12 of the manifold while the pipes 71 and 72 convey primary mixture from the passages 61 and 63 to secondary mixing chambers formed in the manifold branches 11 and 13. These pipes are connected at one end to the outlets of the elbow-shaped passages previously described while the other ends of such pipes connect with elbows 74 detachably secured to the manifold branches 11 and 13, the outlet ends of such elbows being in alignmentwith tubes 75 and 76 which are secured in manifold branches 11 and 13 respectively in any suitable manner. The primary mixture flowing through the above described pipe connections may be mixed with additional air in the secondary mixing chambers in a manner more fully described later.

Substantially all the air entering the carburetor flows through the air horn 20, the flow therethrough being controlled by a main air valve 77, normally held against a seat 7 8 by a spring 79. Air flows past the valve 77 to a main air chamber 80 formed in the housing 18. An air conduit 81 controlled by a valve mechanism-hereinafter described connects the air chamber with the main air manifoldV while an orifice 82 in the fioor of the 'air' chamber permits a flow of airfrom the chamber 80-to the primary carburetors.

When the carburetor is choked to start the engine the air valve 77 is held against its seat by means presently described to completely close the main air inlet. To pro- Y vide sufficient air to carry the starting fuel from the primary nozzles to the engine when the carburetor is choked as described an air inlet 83 is provided. This inlet is an elongated slot formedin a plate 84 secured to the housing 18 as shown 1n Fig. 3.

The main air valve 77 is adjustably secured on a stem V86 slidably mounted in a guide s1eeve`87 fixed in the main housing 18. `Surrounding the guide sleeve 87 is a slidable sleeve 88, .the lower end of which has a projecting disc 89 secured thereto, the disc providing a seat for the air valve spring 79.

Means are provided for raising this sleeve to a position where the upper end thereof will engage the air valve to hold it against its scatto choke the carburetor. This means comprises an arm 90 secured to a rock shaft 91 rotatably mounted in the wall of the main housing 18. The arm at its inner end has two pins 92 and 93 secured therein between which the disc 90 is received. The shaft 91 projects through the wall of the casing and at its outer end is bent to form an arm 200 having a hole 201 therein in which some form of operating connection, extending from a point convenient to the operator may be attached. An adjustable stop screw 202 is received in a lug detachably secured to the air horn as indicated in Fig. 2. By adjustment'of the stop screw the normal position of the sleeve 88 may be determined to regulate the tension of spring 79. Ordinarily the stop screw is so adjusted that the main air valve will open slightly during idling.

During operation at all engine speeds below that corresponding to a vehicular speed of substantially 20e25 miles per hour on a level road the mixture formed in the primary carburetors is of properly combustible proportions and such mixture is, conveyed to the engine without dilution by admixture` with additional air in the secondary mixing chambers. At higher engine speeds, unless means are provided to prevent such action, the velocity of the air current passing the nozzles becomes so great that a velocity head is built up at the nozzles and increases to such a degree that fuel is caused to flow from the nozzles rapidly enough to form a primary mixture which is super-rich in fuel content. To prevent this increase in fuel flow the air passage 81 leading from chamber 80 to the main air manifold is bpened in a manner hereinafter described, to permit a fiow of air through the secondary air passage. This admission of air through the secondary air passage not only` dilutes the mixture but also prevents any increase in air velocity at the nozzles. In fact the velocity vat said nozzles actually decreases with resulting decrease in suction, subsequent to the opening of the air passage so that the valve 49 must be opened, by means later described, as the air passage is opened, to compensate for this reduction in suction atthe fuel nozzles, for reasons set forth fully in copending application, Serial No. 288,683.

Flow of air from the chamber 80 to the secondary mixing chambers is controlled by a butterfly valve 94. which may be termed an air throttle fixed on a shaft 95 journalled in the walls of housing 18. This valve is operated by the operating connections of the primary throttle valve but Iits operation is so controlled that its opening movement is always Y mary throttle for a purpose fully explained.

'vided with a hole in its free end in which is adapted to be connected some suitable operating connection which extends to a point convenient to the operator of the vehicle. The arm 96 is connected to a similar operating arm 97, secured by a split clamp 98 to one end of shaft 95. The connecting means between the two arms 96 and 97 comprises a link 99 having slots 100 and 101 formed therein which receive respectively pins 102 and 103 projecting from the operating arms 96 and 97. 'lhe upper end of a tension spring 104 is connected to the upper end 'of the link and is adapted to operate the link as later described, while the lower end of said spring is connected to the pin 102 projecting from the primary throttle operating arm 96, and said spring normally holds the link 99 in such position that the pin 103 is in the upper end of slot 101 throughout the opening movement of valve 94.

On the end of shaft 95 lopposite to that on which the arm 97 is connected a cam 105 is adjustably secured by any suitable means such as a set screw. This cam engages an enlarged head 106 on the upper end of a piston rod 107 having a piston 108 at its lower end. The piston is received in a cylinder 109, provided with a projecting flange 110 secured by screws to the housing 18. The cylinder is provided with an air vent 111 to permit es- 4cape of air on downward movement of said piston and a compression spring 112 tending to lift the piston is received in the cylinder below said piston'. The cam 105 lowers `the piston on opening of valve 94 and the cylinder and piston form an air dash pot which resists any opening movement of the valve.

' The operation of the above described valve operating mechanism will now be described. When the primary throttle and valve 94 are both closed the parts occupy the position shown in F ig. 10 with the pin 102 at the top of slot 100 and the pin 103 will be spaced from the top of the slot 101. This is true because on clockwise movement of the arm 96 the valve 94 reaches closed position before the primary throttle is closed and the additional movement of arm 96 necessary to close the primary throttle raises link 99 so that the upper end of slot 101 is moved away from pin 103. The spring 104, however, holds the pin 102 in top of slot 100 during this movement. To open the primary throttle the arm 96 is moved counter-clockwise and the first movement of said arm will partially open the primary throttle, but will have no eli'ect on valve 94.

During the first part of the opening movemoves downwardly, moving the link 99 downwardly until the upper end of a slot 101 engages the pin 103.

The valve 94 is opened through the medium of spring 104 which pulls the link 99 downwardly to open the valve by means of arm 97 and it will be clear that the tension of the spring must be always greater than the resistance of the dash pot in order to move the arm 97. The operating arm 96 is moved counter-clockwise and because of inertia and the resistance of the dash pot this movement of the arm 96 moves the pin 102 away from the upper end of the slot 100 and stretches the sprin 104 increasing its tension. The tension o the spring being great enough to overcome inertia of the parts and the resistance ofthe dash pot, said spring will gradually 'open the valve 94 lowering the link 99 until the upper end of slot 100 engages pin 102 which is held in fixed position by the operating connection extending to the dash or other portion of the vehicle. The parts always come to rest with the pin 102 occupying the upper end of the slot 100, and any subsequent opening movement of the primary throttle will result in delayed opening of valve 94 in the manner above set forth.

Moreover, the valve 94 can only open 4as rapidly as the dash. pot permits, so that,'a1 though it may start opening almost as soon as the throttle when the latter is opened from any given position, the completion of the opening movement of valve 94 is consider-,

ably delayed relative yto that of the throttle, irrespective of the distance through which the throttle is opened. For example, it may be assumed that the engineis running at a speed corresponding to a vehicular speed of 30 miles per hour. At such a speed the throttle and valve 94 are both partially open and pin 103 occupies the top of slot. 100. The throttle may then be opened by a single rapid movement lenough to increase the engine speed to that corresponding to a vehicular speed of 50 miles per hour. Inertia of they parts and the resistance of the dash pot will be overcome almost immediately so that valve l 94 will start to open almost as soon as the throttle, but the air escapes slowly from the dash pot compelling the valve 94 to open relatively slowly while the throttle movement is very rapid. The valve 94, therefore, does not complete its opening movement until after the throttle has come to rest. Further, by adjustment of the cam on shaft 95 the distance through which the dash pot piston must move for any given movement of the throttle can be varied, thus varying the retarding ef- 'fect of the dash pot.

It will be understood that while an air dash pot has been shown herein, a liquid dash pot positioned in the fuel bowl could be em-'.

ployed with just as advantageous results. At-

5 mary mixture tention is also called to the fact that the slot 101 should be of suchlength that when-the valve 94 is closed, the slot extends below the pin 103 in order to permit adjustment of arm 197 for the purpose of regulatin the idling adjustment of the primarythrott e.

On any increase of en me s d the suction below the air valve 7 is increased and the air valve is opened against the tension of its spring permittin a suicient i'low of air past said valve to ean the mixture unless means are provided to retard the o ning of the valve. By retarding the opening of the valve liutterlng of the valve as well as leaning of the mixture may be prevented.

To retard the opening movement of the air valve in the manner described the lower end of the air valve stem has secured thereto a iston 120 -which slides in a cylinder 121 lbrmed in the casting 25. The piston 1s secured on the end of stern 86 by a nut 122 in a manner full set forth in the above mentioned copen ing ap lication. The lower end of the c linder is closed by a closure member 123 t rough which fuel flows to the cylinder 121 from the fuel bowl. A check valve (not shown) is provided to control this fuel flow, permitting free upward movement of the piston, while fuel escapes in the downward movement thereof only byy leakage around the piston or through the delivery passage of a pump, later described, whereby the downward movement of the piston and opening of the valve is materially retarded.

The dash to pass around the piston when the piston passes below the upper end of the by-pass, thus relieving the dash pot. As this by-pass forms no part of the resent invention and its construction and unction is fully described in the above mentioned application it is not shown herein.

Wlen the valve 94 is opened the suction below the main air valve 77 is so greatly increased that although the suction at thev nozzles is increased and at the same time the opening of the main air valve and the valve 94 is retarded to some extent to prevent leaning of the mixture the additional air flow to the manifold through the secondar air passage past the valve 94 would be enoug to form a mixture too lean for the most desirable acceleration unless means are provided to offset the action described. To supply a rich enough mixture for proper acceleration a fuel pump hereinafter fully described, is provided, an the retardation of the openlng movement of valve 94 aids the action of the pump.

The opening of the valve 94 is delayed as above set forth for the purpose of producing at all times a suiiicient pressure differential between the inlet and outlet end of the pritubes to create a velocity of pot cylinder 120 may be kprovided with a by-pass in its wall which allows liquid e flow through such tubes great enough to transport the primary mixture' from the priair passage would reach the secondary mixing cham ers before the su er-rich mixture and would temporarily wea entering the engine ports.

By retarding the openin this diiiiculty is avoided. he suction at the outlet ends of the primary mixing tubes is maintained high enough to reduce so high'a velocity of airflow through) said tubes that the super-rich mixture reaches the secondary mixing chambers substantially simultaneously with the opening of the throttle. Of course, the delayed o enin of the air valve `94 also retards the ow o air through the mam air passage to-some extent during the accelerating period, so that the time intervals necessaryfor the su er-rich mixture and secondary air to reac the secondary mixing chambers approach each other and become substantially e ual.

It will be un erstood, that, while the means for delaying the opening of the secondary air valve is particularly applicable to a charge formin device such as shown herein, which .is provided with a fuel pump forcing fuel into the primary mixture passages its utility is not confined to such a device. It would useful in a device not equipped with the pump, or in one euuipped with a diiferent form of ump. T e valve wou d interfere with pro r acceleration of the engine just as muc if the fuel content of the primary mixture were not increased on opening of theA throttle. It is obviousl desirable to secure immediate delivery o a primary mixture of normal proportions to the secondary mixing chamber on opening of the throttle. Otherwise the mixture reaching the engine cylinder would be weakened and the engine temporarily starved.

As above stated the opening of the valve 94 is delayed on any opening movement of the throttle to keep the increased supply of pure air, resulting from the opening of said valve, from reachin the secondary mixing chambers until suicient time has elapsed to permit the primary mixture, which in this particular embodiment of the invention is enriched by a fuel pump, to reach the seconden the mixture of the valve 94' ree opening of the" y ary mixing chambers.

This fuel pump will now be described..

The air valve dash' pot, comprising piston 120 and cylinder 121, constitutes the pump,` which operates whenever the piston moves downwardly on opening of the air valve, and the by-pass in the cylinder is not completely uncovered before the downward movement of the piston begins. A fuel delivery conduit 130 is received at its lower end 1n a hole in the cylinder 121 near the bottom thereof while the upper outletvend of said condult connects with a fuel channel 131 in a block 132 secured in any desirable manner to the bottom of the distributor bloeli in a position somewhat posterior to the prlmary throttle as indicated in Fig. 3. The block 132 extends across all of the primary mixture passages and fuel passages 133, 134, and 13 5, formed in said block, communicate respectively wlth passages 136, 137, and 138 drilled in the bottom wall of the distributor block, and communicating with the prlmary mixture passages 61, 62 and 63 respectively as shown 1n Figs. 3 and 14. Two air channels 139, one of which is shown in Fig. 3, admit a1r to the fuel channel 131, the entering air forming anemulsion with the fuel .which issues from passages 136, 137 and 138 into the primary mixture passages.

Air is admitted to the fuel channel'131 to prevent the high suction maintained in the primary carburetors acting to draw fuel from the dash pot cylinder independently of the pumping action of the piston 120. It will be understood that under all conditions of operation a very considerable degree of suction is maintained in the primary mixing chambers and unless the fuel delivery passage from the pump be vented to atmosphere at some point therein, this high suction would operate to lift fuel from the dash pot cylinder at all times, whereas it is desirable to deliver fuel from said cylinder to the primary mixture passages only when the throttle is opened to cause downward motion of the piston 120. By admitting air to channel 131 the suction effective to draw fuel through conduit 130 is never enough to lift the fuel to channel 131, but is suflicient to lift the fuel to a point intermediate the cylinder 121 and channel 131, preferably to a point just below the channel.

In addition to the above described pump operating to enrich the mixture for acceleration another means is provided in the device herein disclosed for supplying additional fuel at higher speeds, comprising mechanism for opening the valve 49 previously referred to. This mechanism includes an arm 140 pivoted at 141 on the outside of housing 18, as shown in Fig. 8. Projecting from the opposite end of the arm 140 is a pin 142 which is received in a bore in an enlarged head 143 into which the valve 49 is screwed. A cam 144 is fixed in the spindle 67 projecting from thc @11d of the throttle 65 opposite to that on which the arm 96 is secured and cooperating with this cam is a roller 145 rotatably mounted on a pin projecting from the arm 140. A considerable part of the cam is concentric relative to its operating shaft so that it is ineffective to raise arm 140 to movethe fuel valve until a certain predetermined speed is reached, for example, an engine speed corresponding to a vehicular speed of 20-25 miles per hour on a level. By using a cam of different shape the engine speed at which the fuel valve begins to -move may be regulated as desired. Also by adjusting the valve in its head 143 the normal position of the valve prior to its opening movement by arm 140 may be determined.

The secondary mixing chambers comprise Venturi tubes 150 or other flow accelerating elements. There are three of these venturis which are identical in construction and are positioned in the branches 11, 12 and 13 of the manifold 10, in such relation to the primary mixing tubes that the point of greatest depression or suction in each Venturi tube is immediately adjacent the outlet end of the primary mixing tube associated therewith.

4 ach venturi is provided with an annular projecting rib 1,51 which fits, when the manifold is attached to the engine block both in the engine intake port and in a recess 152 in the end of the associated branch of the manifold, the rib engaging shoulders 153 and 154, in the manifold and intake port respectively, when the venturi is in position. A channel 155 is formed in the outer wall of each venturi, at the bottom of the element when the device is assembled, to permit any fuel which precipitates o ut of the mixture and collects on the wall of the manifold branch to flow into the engine intake port. The Venturi tubes cause the air entering the air manifold to move past the ends of the tubes 70, 75 and 76 at high velocity, creating in each of the tubes a high suction at all times.

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.

Vhat is claimed is as follows:

1. A charge forming device for internal combustion engines having in combination a mixing chamber, a fuel inlet, a primary air inlet, a primary throttle, a secondary air passage having an air throttle therein, means operating independently of the engine suction for opening said air throttle as the primary throttle is opened and means for delaying the opening of the air throttle relative to the opening of the primary throttle on all opening movements of the latter.

2. A charge forming device for internal combustion engines having in combination a mixing chamber, a fuel inlet, primary air and means for delaying the opening of the the opening of the primar throttle-on all opening movements air throttle relative to of the atter.

3. A charge forming A device for internal combustion engines having in combination'a mixing chamber, a fuel inlet, a primary air inlet, a primary throttle, asecondary air passage having an ainthrottle therein, operating means for the primary throttle, means connecting the air throttle to said primary throttle'for operation therewith independently of the engine suction, said means including a lost motion connection to4 permitpartial opening of the primary throttle independently ofthe air throttle and means for delaying the opening of the air throttle relative to the opening of the primary throttle on all opening movements of the latter.

4. A charge forming device for internal combustion engines comprising a mixing chamber, a fuel inlet, a primary air inlet, a primary throttle, a secondary passage hav.- ing an air throttle therein,'means for operating the primary throttle, resilient manually operable means for opening the air throttle, means for resisting the opening of said air i throttle by said resilient means, and means for varying the effect of said resistingmeans as desired.

5. A charge forming device for internal combustion engines comprising a mixing chamber, a fuel inlet, a primary air inlet, a primary throttle, a secondary passage having an air throttle therein, means-for operating the primary throttle, resilient manually operable means for opening the air throttle, a dash pot for resisting the opening movement of said air throttle and a cam operating with said air throttle for operating said dash Ut; I p 6. A charge forming device for internal combustion engines comprising a mixing chamber, a fuel inlet, a primary air throttle, a secondary air passage, an air throttle therein provided with an operating shaft, means for operating said primary and secondary throttles, a dash pot for resisting the opening of said air throttle, and a cam on the air throttle shaft for operating the dash pot.

7. A charge forming device for internal combustion engines having in combination, a primary mixture passage, means for supplying fuel and air thereto, a primary throttley in said mixture passage, a secondary mixing chamber into which said primary mixture passage delivers, a secondary airpassage admitting air to said secondary mixing chamber, an air throttle in said secondary air passagel controlling admission of air a plurality of vently of the air vthrottle relative to th therethrough, means for operating said throtber, an air throttle' -in said secondary air passage controlling admission of air therethrough, means connecting the air throttle to the primary throttle for operation therewith and means for retarding the opening movement of the air throttle relative to the opening movement of the primary throttle under all'operating conditions. 9. charge forming device for multi-cylinder internal combustion engine comprising a plurality of secondary mixing chambers,

to deliver fuel mixture to said secondary mixing chambers, mixture passages for conveying the primary mixture to said secondary mixing chambers, a 'single primary throttle for controlling flow through all of said mixture passages, a secondary mitting air to all of said secondary mixing chambers, an air throttle in said passage, means for operating `said throttles constructed to permit a predeterminedl opening movement of the primary throttle independthrottle, and means for retarding all opening movements of the air e opening of the primary throttle,

10. A charge forming device for multi-` cylinder internal combustion engine comprising a plurality of secondary mixing chamers, a plurality of primary carburetors adapted to deliver fuel mixture to said sec'- ondary mixing chambers, mixture passages for conveying the primary mixture to said secondary mixing chambers, a single primary throttle for controlling flow through all of said mixture passages, a secondary air passage for admitting air to all of said secondary mixing chambers, an air throttle in said passage, means for operating said throttles constructed to permit a predetermined opening movement of the primary ently of the air throttle, and means for holding said air throttle closed during the initial opening movement of the primary throttle and for retarding all opening movements of the air throttle relative to the opening of the primary throttle.

11. A 'charge forming device for multicylinder internal combustion engine comprising a plurality of secondary mixing chambers, a plurality of primary carburetors adapted to deliver fuel mixture to said secondary mixing chambers, mixture passages air passage for adthrottle independprimary carburetors adapted for conveying the primary mixture to said secondary mixing chambers, a single primary throttle for controlling flow through all of said mixture passages, a secondary air passage for admit-ting air to all of said secondary mixing chambers, an air throttle in said passage` means for operating said throttles constructed to permit a predetermined opening movement of the primary throttle independently of the air throttle, .and a dash pot for holding said air throttle closed during the initial opening movement of the primary throttle and for retarding all opening movements ofthe air throttle relative to the opening of the primary throttle.

12. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttle for controlling the flow of the primary mixture, a secondary air supply mea-ns adapted to admit air to the mixture passage at a point posterior to saidl primary throttle, an air throttle in the secondary air passage, means for opening said air throttle concurrently with the opening of the primary throttle and means for delaying the opening movement of the air throttle with respect to that of the primary throttle on all opening movements of the latter.

13. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttle for controlling the flow of the primary mixture, a secondary air supply means adapted to admit air to the mixture passage at a point posterior to said primary throttle, an air throttle in the secondary air passage, common operating means for the two throttles and means for delaying the opening of the air throttle relative to the opening of the primary throttle on all opening movements of the latter.

14. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttlefor controlling the How of the primary mixture, a secondary air supply means adapted to admit air to the mixture passage at a point posterior to said primary throttle, an air throttle in the secondary air passage, means connecting the air throttle to said primary throttle for operation therewith and having a lost motion connection formed therein to permit partial independent opening movement of the primary throttle, and means for delaying the opening of the air throttle relative to the opening of the primary throttle on all opening movements of the latter.

15. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttle for controlling the flow of the primary mixture, a secondary air supply means adapted to admit air to the mixture passage at a point posteriorto said primary throttle, an air throttle in the secondary air passage, means for operating the primary throttle, a resilient operating connection between said last named means and the air throttle and means for resisting the opening movement of the air throttle whereby its movement is delayed relative to the movement of the primary throttle.

16. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttle for controlling the flow of the primary mixture, a secondary air supply means adapted to admit air to the mixture passage at a point posterior to said primary throttle, an air throttle in the secondary air passage, resilient means connecting the air throttle with the primary throttle for operation therewith, and a dashpot for preventing any opening movement of said air throttle until the force exerted by said resilient operating connection is effective to overcome the resistance of said dashpot.

17. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttle for controlling the flow of the primary mixture, a secondary air supply means adapted to admit air to the mixture passage at a point posterior to said primary throttle, an air throttle in the secondary air passage, resilient means connecting the air throttle with the primary throttle for operation therewith, said means including a lost motion connection eftective to permit a partial opening movement of the primary throttle before said resilient means is effective to exert a force on said air throttle tending to open the latter, and a dashpot for delaying t e opening of the air throttle relative to the primary throttle on all opening movements of the latter.

18. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a primary throttle for controlling the iow of the primary mixture, a secondary air supply means adapted to admit air to the mixture passage at a point posterior to said primary throttle, an air throttle in the secondary air passage, means connecting the air throttle to the primary throttle for opening movement therewith and constructed to permit an independent initial opening movement of said primary throttle, and a dashpot for preventing movement of the air throttle during such initial movement of the primary throttle.

19. A charge forming device for internal combustion engines comprising a mixture passage having a primary mixing chamber formed therein, means for supplying fuel and air to said primary mixing chamber, a mixture throttle in said mixture passage, a secondary air passage admitting air to the mixture passage at a point remote from the primary mixing chamber, an air throttle therein, means for opening said air throttle as the primary throttle is opened and means for delaying the opening of said air throttle relative to the opening of said primary throttle on all opening movements of the latter.

20. A charge forming device for internal combustion engines comprising a secondary mixing chamber located adjacent the engine intake port, a primary mixture conduit adapted to deliver a primary mixture of air and fuel to said secondary mixing chamber, a primary mixing chamber in said conduit remote from said secondary mixing chamber, means for supplying fuel and air thereto, a primary throttle, a secondary air passage supplying air to said secondary mixing chamber and having an air throttle therein, means for opening said air throttle Aas the primary throttle is opened, and means for delaying the opening of the air throttle relative to the opening of the primary throttle on all opening movements of the latter.

21. A charge forming device for internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary carburetors adapted to deliver a primary mixture of fuel and air to said secondary mixing chambers, mixture passages for conveying the primary mixture to said seoondary mixing chambers, a single primary throttle for controlling the flow through all of said primary mixture passages, a secondary air passage for admitting air to all of said secondary mixing chambers, an air throttle in said passage, means for operating said th rottles constructed to permit a limited opening movement of the primary throttle independently of the air throttle, and means for delaying all opening movements of the air throttle relative to the primary throttle.

22. A charge forming device for internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary carburetors adapted to deliver a primary mixture of fuel and air to said second"\ ary mixing chambers, mixture passages for conveying the primary mixture to said secondary mixing chambers, a single primary throttle for controlling the flow lthrough all of said primary mixture passages, a secondary air passage for admitting air to all of said secondary mixing chambers, lan air throttle in said passage, means for operating said throttles constructed to permit a limited' opening movement of the primary throttle independently of the air throttle and means for holding said air throttle closed during said initialopenin movement of the primary throttle and forl elaying allother opening movements of the prlmary throttle relative to the air throttle.

23. A charge forming device for internal combustion engines having in combination, a. secondary mixing chamber, a primary mixture passage adapted to deliver a primary mixture of fuel and air thereto, means for supplying fuel and air to said primary mixture passage, a primary throttle controlling the flow of mixture therethrough, a secondary air passage supplying air to said secondary mixing chamber and having an air throttle therein operable independently of engine suction, resilient means for opening said air throttle as the primary throttle is opened, and means for delaying the openin of the air throttle relative to the opening o the primary throttle.

24. A charge forming device for internal combustion engines, having in combination, a primary mixing chamber, means for supplying fuel and air thereto, a secondary mixing chamber adapted to receive a primary mixture of air and fuel from'said primary mixing chamber, a primary throttle for controlling the How of primary mixture from said primary mixing chamber, a secondary air passage supplying air to said secondary mixing chamber, an air throttle therein, means for opening the air throttle as the primary throttle is opened and means for delayi-ng the opening of the air throttle relative to the opening movementl of the primary throttle on all opening movements of the latter.

25. A charge forming device for internal combustion engines, having in combination, a primary mixing chamber, means for supplying fuel and air thereto, a secondary mixing chamber adapted to receive a primary mixture of air and fuel from said primary mixing chamber, a primary throttle for controlling the flow of primary mixture fromV said primary mixing chamber, a secondary. air passage supplying air to said secondary mixing chamber, an air throttle therein, a single actuating means for operating the primary and air throttles, and means for delaying the opening of the air throttle relative to the opening movement of the primary throttle on all opening movements of the latter.

26. `A charge forming device for internal combustion enginesv comprising a mixing chamber, means for supplying fuel and air thereto, a primary throttle controllingthel flow of mixture therefrom,a secondary air passage having an air throttle therein, a. common operating means for said primary throttlegand air throttle and means for resisting th opening movements of \the nir throttle, wh reby its opening movement is delayed relative to all opening movements of the primary throttle.

In testimony whereof I hereto atlix my signature. WILFORD H. TEETER.

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