US2155104A

US2155104A - Charge forming device

Info

Publication number: US2155104A
Application number: US415496A
Authority: US
Inventors: Wilford H Teeter
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1929-12-20
Filing date: 1929-12-20
Publication date: 1939-04-18
Anticipated expiration: 1956-04-18

Description

April 18, 1939. W. H.V TEETER 2,155,104

CHARGE FORMING DEVICE Filed Deo. 20, 1929 2 Sheets-Sheet l April 18, 1939. W, H TEETER I 2,155,104

CHARGE FORMING DEVICE Filed Dec. 2o, 1929 2 sheds-sheet 2 Patented Apr. 18, 1939 UNITED STATES PATENT OFFICE CHARGE FORMING DEVICE Application December 20, 1929, Serial No. 415,496

27 Claims.

This invention relates to charge forming devices for internal combustion engines, and more particularly to that type of charge forming device which comprises a plurality of primary carburetors, each of which is adapted to deliver a primary mixture of fuel and air to one of a plurality of secondary carburetors located adjacent the engine intake ports, and in which additional air is mixed with the primary mixture under certain operating conditions before the latter enters the engine cylinders.

An example of a charge forming device of this type is disclosed in the patent of Fred E. Aseltine, Wilford il. Teeter, Carl H. Kindl and Frederick D. Funston, No. 1,913,741, granted June 13, 1933.

It is the object of the present invention to provide improved means for enriching the mixture during the acceleration period, and more particularly to provide an enriching device which is effective to enrich the mixture to the desired extent on any opening movement of the throttle, whether such movement be relatively rapid or relatively slow.

According to the present invention, this object is accomplished by providing in addition to the usual fuel pump, such as described in the above mentioned application, a device which under certain operating conditions, is effective to supply additional fuel during the acceleration period. This fuel is supplied by the auxiliary dashpot, but the construction is such that the dashpot is ineffective to supply the additional fuel at any time other than when the throttle is opened relatively rapidly and through a consider- 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. l is a vertical, longitudinal section through a charge. forming device in which the present invention is embodied.

Fig. 2 is a horizontal section on the line 2--2 a fragmentary view of the lower main the carburetor viewed from below. 4 is a section on the line 4-4 of Fig. 3.

Fi 5 is a fragmentary section on the line 5 5 of Fg- 2 Fig. 6 is a view partly in section, showing the operating mechanism for various valves and for a fuel pump.

The device comprises a main air manifold l0, having three outlet branches, the middle branch l2 being shown herein. Each of these branches communicates with one of the ports of a multicylinder engine and each is provided with an attaching flange I4, which is adapted to be secured to the engine block in the usual way, while adjacent the inlet of the manifold is a flange I6 to which the main carburetor unit, hereinafter described,-is adapted to be secured, as shown in Fig. 1.

The carburetor unit comprises a main housing i8 in the form of a single casting, having a flange 2U adapted to be secured to the flange i6 by screws 22. A valve controlled air inlet coupling 24 is secured in position in an opening in the top of the housing i8 by any desirable means. A casting 26, having certain fuel passages formed therein, is secured by screws 28 to the bottom of the main housing and a sheet metal fuel bowl 3l) is held tight against an annular shoulder 32 on the bottom of the main housing by a screw 34, screwed into the casting 26, suitable gaskets being provided wherever necessary to prevent leakage of the fuel. A fuel conduit, which is not shown herein, supplies fuel to the fuel bowl and the fuel level therein is controlled by a float (not shown) which operates to maintain a substantially constant level of fuel in the usual way.

A plurality of angular mixture passages indicated in their entirety by the reference numeral 36 and hereinafter more fully described, are provided in the lower part of the main housing. Communicating with the vertical portion of these passages through orifices 38, are three chambers 40, which, for convenience, are designated fuel supply chambers. Fuel is admitted directly to these chambers by nozzles 42, which are effective at relatively high speeds, and passages 44, formed in the wall of the main housing and which are effective at relatively low speeds. A small quantity of air is supplied to the chambers by a slot 46, formed in a partition separating said chambers from a main air chamber, which is more fully described later. The mixture of fuel and air formed within the fuel supply chambers ows therefrom through the orices 38 into the primary mixture passage.

Fuel is supplied to the nozzles 42 and the passages 44 through a vertical fuel channel 48, shown in dotted lines in Fig. 1. This channel communicates at its upper end with the horizontal channel 50, which communicates directly with all the nozzles 42 and passages 44, while at its lower end the passage 48 communicates with a calibrated plug 52, which admits fuel from the fuel bowl thereto at all engine speeds and a calibrated plug 54, which is controlled in a manner described in the above mentioned application and is effective to admit fuel to the passage 48 only at relatively high speeds. Each of the nozzles 42 is provided with a metering orifice 56 and each of the passages 44 is provided with a restriction 58 at its upper end to limit the flow of fuel therethrough.

At idling or other operation at low speed, the suction within the chambers 49 is insufficient to lift fuel from the top of the nozzles 42, but is enough to cause a flow from the passages 44, which will supply sufficient fuel to operate at such low speeds. As the speed increases, the suction effective on the nozzles 42 becomes sufiicient to draw fuel therefrom and fuel is supplied to the fuel supply chambers both by the passages 44 and the nozzles 42.

The primary mixture passages are controlled by a single throttle valve 60, which extends across all of said passages, is provided with grooves 62 which register with said passage, and is operated by means more fully described later. The primary mixture passages register with conduits for conveying the primary mixture to the secondary mixing chambers when the'device is assembled. These conduits comprise tubes cast in position in the manifold during the casting of the latter, as fully shown and described in the above copendingapplication. Only the tube 64 for conveying the primary mixture to the secondary mixing chamber, formed in the middle outlet branch of the manifold, is shown herein since the specific construction of said conduits and manifold forms no part of the present invention.

All of the fuel supply chambers 40 communicate with. a 'chamber 66, which may be termed a primary air chamber. The chamber 66 and all of the chambers 49 are separated by the partition plate 68, hereinafter referred to, from a main air chamber 19 and the fuel supply chambers 49 are separated from the vertical portions of the primary mixture passages by a vertical partition 12, which is formed as an integral part of the main housing and on which the partition plate 68 is supported. The fuel supply chambers 40 are separated from each other by vertical partitions 14, also integral with the main housing. All of the air supplied to the carburetor is admitted through the coupling 24 and is controlled by a valve 1S normally held against its seat 18 by a spring 89, received between the valve and a flange 82, projecting from a sleeve 84, slidably mounted on a fixed sleeve 86, which guides the stem 88 on which the air valve 16 is secured. Under normal operating conditions, the sleeve 84 occupies the position shown in Fig. l, but may be lifted by a choke lever 99, as described in the above application, to hold said valve closed for starting purposes. The choke mechanism also forms no part of the present invention.

The valve 16 admits air directly to the main air chamber 1D, which supplies air to the primary air chamber as above set forth and also to the secondary mixing chambers in the manifold by means of a secondary air passage 92, which connects with the manifold inlet. This passage is controlled by a manually voperable valve 94,

secured to a shaft 9S, journalled in the main housing and a suction operated valve 98, secured to a shaft |88 also journalled in the main housing. The operating mechanism for these valves, and the fuel pump hereinafter described, is fully shown in Fig. 6, and comprises an operating plate 9| secured in any desirable way to one end of the primary throttle 50 and having pivotally connected thereto on pin 93 an operating link 95 pivotally connected on a pin 91 with an ops erating arm 99 secured to one end of the spindle 95 on which the secondary throttle 94 is mounted. Also pivotally connected to the operating plate by pin |Ll| is an operating rod |93 adapted to project into a tube |95 extending upwardly from the piston of the fuel pump so as to operate this piston when the rod is moved downwardly by the operating plate. The pivot point 93 of the operating link 95 is so positioned that, during the first part of the movement of said operating plate when the latter is rotated in a clockwise direction, it is almost concentric with the pin 91 so that the point 93 moves substantially in the arc of a circle about the point 91 as a center, without transmitting movement to the arm 99. There is some lost motion provided between link 95 and pin 91 to prevent binding of the parts during this movement, and a spring |91 connected to the pin 91 and a lug |99 projecting from the link, tends to take up this lost motion. The degree of movement of the primary throttle and operating plate 9| without accompanying movement of the arm 99 and secondary throttle may be varied, but the construction is generally such that no such movement takes place until the primary throttle occupies a position corresponding to a vehicular speed of approximately 29 miles per hour on a level. After this initial movement, the arm 91 is moved With the operating plate 9| to effect simultaneous movement of the primary and secondary throttles.

Pivoted on the screw l screwed into the primary throttle, is a bifur'cated arm H3, the two ends of Which embracera rod I5 connected to the piston of the dash pot which controls the auxiliary air valve 98 as later more specifically described. The rod i5 is connected at its upper end to an arm ||1, secured to a spindle ||9 pivoted in the housing. A spring |2| is connected to a lug |23 projecting from the housing and to an ear |25 extending from arm H3. The ends of the arm which engage rod ||5 are below a pin |21 extending through the rod, and cooperate with said pin to lift the rod and return the auxiliary air valve to closed position when the throttle is closed. As the throttle is opened the pin 93 engages the arm ||3, moving it away from the pin |21, and as the throttle is closed, the arm is returned to normal position by the spring |2|, engaging the pin |21 and closing valve 98. When the throttle is open the valve 98 occupies a position Where the force exerted by the valve due to engine suction and the force of the spring are balanced.

The slot 46, which admits air to the fuel supply chambers, is considerably larger than the total area of the three orifices 38, which connect these chambers with the primary mixture passages. Because of this dierence of area of the air inlet and outlet tol the fuel supply chambers, it is obvious that the flow of air through these chambers must necessarily be at low velocity under all operating conditions and at all engine speeds. For this reason, there is substantially no velocity head created at the fuel nozzles, the reason being fully set forth in the earlier application above referred to, and the suction which is effective to cause a flow of fuel from the nozzles is substantially the static suction of the air chamber 10 as determined by the spring of the main air valve.

Whenever the throttle is opened, the suction in the main air chamber is increased and the main air valve 'l5 is opened to permit an increased flow of air past the valve. It has been found necessary to retard the opening movement of this valveto prevent fluttering of the valve and to prevent the admission of sufficient air to temporarily lean the mixture in the primary mixture passages before the valve comes to rest. For this purpose a dashpot comprising a cylinder |52 and a piston |04 secured in any desirable manner tothe lower end of the valve stem S8, is provided. This dashpot is of ordinary construction and is adapted to be filled with fuel from the fuel bowl by leakage around the piston when the air valve is stationary. In order to prevent a tendency of the air valve to enrich the mixture by gradually moving toward closed position because of the action of engine pulsations at relatively low speeds, the piston |94 is provided with small holes |66 therethrough and a check valve comprising a anged sleeve |58 closes the ports, on upward movements of the air valve and piston. The dashpot, therefore, resists closing movements of the valve to a somewhat greater degree than opening movements thereof.

In order to enrich the mixture on` opening movements of the throttle to secure proper operation of the engine during the acceleration period for reasons well known to thdse skilled in the art, a fuel. pump is provided. This pump comprises a cylinder Hl] formed in the casting 26 and a cooperating piston I2, which is slidable therein and operated by the primary throttle through the medium of a rod |33, which projects into a tube |05 extending upwardly from the piston in the manner fully described in the above mentioned application. The piston is normally held in its uppermost position, as shown in Fig. 4, by spring H8, received between the piston and a plate !2|) secured by screws |22 to the bottom of the casting 2B, but on opening movements of the throttle the piston is forced downwardly by the rod |53 to force fuel from the cylinder through -a fuel delivery passage hereinafter described.

This passage comprises a horizontal passage |29, which communicates with a vertical passage |24 having an enlargement |26 at its upper end in which a check valve |28 is received and which operates to prevent the return of fuel to the pump cylinder on closing movements of the throttle, as fully described in the earlier application. The enlargement |25 is connected with a well |39 by an orice |32 between the enlargement and said well. The passages |34 connect the bottom of the well with a vertical chamber |35, which is vented by a passage |38, which connects the top of the chamber |36 with the atmosphere, as indicated in Fig. 2. Chamber |36 is connected by three horizontal passages |40 with three vertical passages !42. The two o-uter passages M2 are connected at their upper ends with horizontal channels |44, formed in the upper surface of the casting 2t and these channels at their outer ends communicate with vert-ical passages |46, formed in 'the main housing and which communicate directly with the two outer primary mixture passages while the middle passage |42 communicates directly with a middle passage |46, which connects with the middle primary mixture passage. 'Ihe fuel iiows from the well |30 to the chamber |36 by gravity and in such chamber is mixed with air supplied thereto through the passage |38 to form an emulsio-n of fuel and air which is drawn into the primary mixture passages through the various passages above described, by the suction maintained in said mixture passages. Air is admitted to the chamber |36 so that the suction in the various fuel delivery passages between the check valve and the primary mix ture passages is never suiiicient to draw fuel from the pump cylinder into said mixture passages and fuel is only delivered to the mixture passages on the downward stroke of the pump piston. Each of the vertical passages |46 is provided with a restriction |48 adjacent its outlet end to regulate the ow of fuel.

It has been found necessary in order to secure the desired enrichment of the mixture on operation of the pump to provide means for temporarily retarding the opening of the suction operated valve 98 following opening movements of the manually operated valve S4. This is necessary in order to produce a sufficient pressure differential between the inlet and outlet ends of the primary mixture conduits to create a velocity of ow through said conduits great enough to transport the enriched primary mixture from the fuel supply chambers lil to the secondary mixing chambers almost instantaneously. It is a considerable distance from the fuel supply chambers to the secondary mixing chambers and if the valve 93 were permitted to open freely an appreciable time interval would be necessary for the rich and relatively heavy primary mixture to travel through this distance, obviously a greater time interval than that required for the pure air to travel from the valve 94 to the secondary mixing chambers. By retarding the opening of the valve 98, the time interval necessary for the primary mixture to reach the secondary mixing chambers is reduced, while that necessary for the air flowing past the valve 9d to reach said chambers is increased, whereby these two intervals are substantially equalized, with the result that the primary mixture and secondary air reach the secondary mixing chambers at substantially the same time.

In order to retard the opening of the valve 98, for the purpose above described, it is connected, in the manner described in the above mentioned. application, to a link |5, which is pivotally conn nected at its lower end to a piston i 52, slidable in a cylinder |54, formed in the casting 25, as shown in Fig. 5, the piston and cylinder forming a dashpot which retards the opening movement of said valve. The cylinder IM communicates with the fuel bowl through a passage |56 in the bottom of the cylinder to admit fuel to the cylinder on closing movement of the valve and a check valve |58 prevents a flow through such passage on opening movement of the valve, as fully described in the above mentioned application. In order to regulate the retarding effect of this dashpot so as to retard the opening of the valve to substantially the same extent at whatever position the valve may occupy when its opening movement begins, an auxiliary cylinder E59 is formed in the casting 25 immediately adjacent the cylinder |54 and connecting with the latter oy means of an orice |65 at the bottom of said cylinders. Sliding within the cylinder |59 is a piston |52 Cil normally held in thev position shown in Fig. 5 by a spring |64, received between the piston and the top of the cylinder. On downward movement of the piston |52, the auxiliary piston |62 is lifted by the pressure of the fuel beneath said piston and the fuel above the piston |62 escapes from the cylinder |59 through an orifice |66 near the top of the cylinder, the rate of escape of fuel through this orifice determining the retarding effect of the dashpot on the valve 98. After the valve has completed any opening movement, the spring |64 forces the piston |62 toward its eriginal position and the cylinder |59 is filled with fuel from the fuel bowl through the orifice |66. It will be clear, therefore, that the auxiliary piston |82 occupies the same position whenever an opening movement of the valve 98 takes place so that the retarding effect of the controlling dashpot on such valve is substantially the same for every opening movement thereof.

It has been found that under certain operating conditions, as when the throttle is opened to a considerable extent and relatively rapidly, the above described fuel pump is'ineffective to supply sufficient fuel to enrich the mixture to the desired extent or to supply fuel for a long enough period of time to enable smooth and rapid acceleration, but if opened slowly, the pump is effective to supply enough fuel. This is due to the fact that when the throttle is opened through a considerable distance and relatively rapidly so much of the fuel which is pumped into the well flows back into the fuel bowl, because of the relatively small size of the well that what is delivered to the mixing chamber, is insufficient in quantity to effect proper acceleration, and is drawn into the mixture passages too rapidly to enrich for the desired length of time. The capacity of the well, however, can not be increased without reducing the size of the pump, because on slow openings of the throttle there would be so little overflow that too large a quantity of fuel would be retained by the larger well and the mixture enrichment during acceleration would be too great, the present well being of proper size to enrich the mixture to the desired extent on all relatively slow opening movements of the throttle.

According to this invention, the auxiliary air Valve and the devices which retard its opening movement have been employed to supply fuel to the mixture passages on rapid opening of the throttle in addition to that supplied by the fuel pump and to prolong the time during which such fuel is supplied, but these devices are ineffective on all other opening movements of the throttle. For this purpose an angular passage |10 is formed in the wall of the casting 2S and communicates with the cylinder |59, a short distance from the bottom thereof, for example, a quarter of an inch. The other end of the angular passage il@ communicates with a horizontal passage |12, which connects with the fuel delivery passage |24 leading from the fuel pump. Normally, the end of the passage |19 which connects with the cylinder |59 is covered by the piston |62, and if the throttle is opened slowly, the opening of the air valve 98 is ineffective to lift the piston |62. The fuel displaced by the dashpot piston |52 escapes by leakage past said piston and the piston |92 so that on slow opening movements of the throttle the auxiliary fuel supply means above described, is ineffective. If, however, the throttle is opened rapidly, downward movement of the piston |52 lifts the piston |62 so that fuel may pass from the cylinder |59 through the passages |10 and |12 to the fuel delivery passage |24 and thence to the primary mixture passages. As the movement of the piston |52 is a delayed movement relative to the opening of the throttle, this additionalfuel is supplied to the mixing chambers about the time when the fuel, forced into said mixing chambers by the pump, is exhausted. It will be clear, therefore, that this device is effective to supply additional fuel to the primary mixture passages and to prolong the period through which the additional fuel is supplied thereto.

The secondary mixing chambers may comprise any means heretofore used for accelerating the flow of air past the ends of the primary mixture conduits. means which is employed is indicated by the reference numeral IBG and is of the same form as that disclosed in the earlier application. Since this element is in no way a part of the present invention, it need not be described in detail herein.

It will be understood that the distance between the bottom of the auxiliary cylinder |59 and the passage |10 may be varied as desired and springs of different strength may be substituted for the spring Hifi to give whatever result is desired for any specific engine construction.

While the form of embodiment of the present invention as herein disclosed7 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.

What is claimed is as follows:

1. A charge forming device for an internal combustion engine comprising a mixture passage,

means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, a means for supplying additional fuel to the mixture passage on opening movements of the throttle to enrich the mixture during the acceleration period, an air valve and an auxiliary pump operated by the air valve for supplying additional fuel to the mixture passage during the acceleration period.

2. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, a fuel pump operated by said throttle for supplying additional fuel Af to the mixture passage during the acceleration period, an air valve and an auxiliary pump operated by said air valve for supplying additional fuel to said mixture passage during the acceleration period.

3. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, means for supplying additional fuel to the mixture passage on all opening movements of the throttle to enrich the mixture during the acceleration period, an air valve, and means operated by said air valve for supplying additional fuel to the mixture passage only on relatively rapid opening movements of the throttle.

4. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, a fuel pump operated by said throttle on all opening movements thereof to supply additional fuel to the mixture passage, an air valve and means operated by said f In the device disclosed herein the air valve to supply additional fuel to said mixture passage only on relatively rapid opening movements of the throttle.

5. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, means for supplying additional fuel to the mixture passage on opening movements of the throttle, a port admitting auxiliary air, an auxiliary air valve controlling admission of air therethrough, and an auxiliary pump operated by said air valve for supplying additional fuel to said mixture passage during the acceleration period.

6. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, means for supplying additional fuel to the mixture passage on all opening movements of the throttle, a port admitting auxiliary air, an auxiliary air valve controlling admission of air therethrough and an auxiliary pump operated by the auxiliary air valve to supply additional fuel to the mixture passage, following relatively rapid opening movements of the throttle.

7. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the oW through said mixture passage, a fuel pump operated by the throttle on all opening movements thereof, a port admitting auxiliary air, an auxiliary air valve controlling the admission of air therethrough, and means operated by said air valve only on relatively rapid opening movements of the throttle, to supply additional fuel to the mixture passage.

8. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the iiow through said mixture passage, means operated by the throttle for supplying additional fuel to the mixture passage, main and auxiliary air valves for controlling the supply of air thereto and means operated by said auxiliary air valve for supplying additional fuel to the mixture passage only on rapid opening movements of said throttle.

9. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage delivering a primary mixture of fuel and air thereto, means for supplying fuel and air to said mixture passage, a primary throttle controlling the flow through said primary mixture passage, an auxiliary air valve regulating the admission of air to said secondary mixing chamber, means operated on opening movements of the primary throttle for supplying additional fuel during the acceleration period and means operated by the auxiliary air valve for also supplying additional fuel during the acceleration period.

10. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage delivering a primary mixture of fuel and air thereto, means for supplying fuel and air to said mixture passage, a primary throttle controlling the 110W through said primary mixture passage, a main air valve, an auxiliary air valve controlling admission of air to said secondary mixing chamber, devices operated by the primary throttle and by the auxiliary air valve for supplying additional fuel during the acceleration period.

11. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage delivering a primary mixture of fuel and air thereto, means for supplying fuel and air to said mixture passage, a primary throttle controlling the floW through said primary mixture passage, an auxiliary air valve controlling admission of air to the secondary mixing chamber and adapte-d to open only after the throttle has made a predetermined opening movement, means operated by said throttle for supplying additional fuel during the acceleration period and means operated by the auxiliary air valve for also supplying additional fuel during the acceleration period.

12. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage .delivering a primary mixture of fuel and air thereto, means for supplying fuel and air to said mixture passage, a primary throttle controlling the flow through said primary mixture passage, an auxiliary air valve controlling admission of air to the secondary mixing chambers and adapted to open only after the throttle has made a predetermined opening movement, means operated by the throttle on all opening movements thereof for supplying additional fuel during the acceleration period, and means operated by the auxiliary air valve for also supplying additional fuel during the acceleration period following certain opening movements of the throttle.

i3. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, means for supplying additional fuel to the mixture passage on all opening movements of the throttle, and an auxiliary fuel pump for supplying additional fuel to the mixture on opening movements of the throttle said pump being effective only after said throttle has reached a predetermined position.

14. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, means operated by the throttle for supplying additional fuel to the mixture passage on opening movements of the throttle, an air valve controlling admission of air to said mixture passage and means operated by said valve for supplying additional fuel to the mixture passage on opening movements of the throttle only after said throttle has reached a predetermined position.

15. A charge forming device for an internal combustion engine comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle for controlling the flow through said mixture passage, a fuel pump for supplying additional fuel to the mixture passage on opening movements of the throttle to enrich the mixture during the acceleration period, and a suction operated auxiliary fuel pump for also supplying additional fuel during the acceleration period.

16. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, positively and yieldingly operated fuel pumps for supplying additional fuel to the mixture passage ,during the acceleration period, and means Whereby the yieldingly operable pump becomes effective at substantially the same time the other of said pumps becomes ineffective.

17. A charge formingdevice for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a fuel pump positively operated as the throttle is opened to supply additional fuel to the mixture passage, substantially simultaneously with the opening of the throttle, a suction operated pump for also supplying fuel to the mixture passage during the acceleration period, and means whereby the action of the suction operated pump is delayed with respect to the opening of the throttle.

18. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a suction operated valve admitting auxiliary air to said lmixture passage, a fuel pump operated thereby, and common means for retarding the operation of said auxiliary air valve and fo-r controlling the delivery of fuel by said pump.

19. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a suction operated valve admitting auxiliary air to said mixture passage, a fuel pump operated thereby, a fuel delivery passage leading from said pump to the mixture passage and means for retarding the operation of said auxiliary air valve and for controlling the opening and closing of said fuel passage. i

20. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a suction operated valve admitting auxiliary air to said mixture passage, a fuel pump operated by said air valve on opening movements thereof and means for delaying the delivery of fuel -by said pump with respect to the opening of said valve.

21. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a suction operated valve admitting auxiliary air to said mixture passage, a dashpot comprising a cylinder and av piston slidable therein for controlling the movementk of the auxiliary air valve and operating as a fuel pump for delivering fuel to the mixture passage during the acceleration period, and an auxiliary cylinder having a piston therein for controlling the retarding effect of said dashpot and the delivery of fuel therefrom.

22. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a suction operated Valve admitting auxiliary .air to said mixture passage, a fuel piunp operated thereby, comprising a piston and cylinder in which said piston slides, an auxiliary cylinder communicating with the pump cylinder, a fuel delivery passage leading fro-m the auxiliary cylinder to the mixture passage and a piston in said auxiliary cylinder normally closing the fuel delivery passage.

23. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle controlling the flow through said mixture passage, an auxiliary air valve for ,admitting additional air to the mixture passage,

main and auxiliary fuel pumps operated by said i throttle and auxiliary air valve respectively.

24. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air to said mixture passage, a throttle controlling the flow through said mixture'passage, a fuel pump connected to the throttle fo-r operation simultaneously therewith, an auxiliary air inlet valve, a dashpot comprising a cylinder .and a piston slidable therein for controlling the movement of the auxiliary air Valve, said dashpot comprising a fuel pump, an auxiliary cylinder forming a part of the fuel delivery passage from said pump, and a piston in said cylinder for regulating the retarding effect of the dashpot and delaying the delivery of fuel with respect to the opening of the air valve.

25. In a fuel supply system for internal combustion engines, in combination, means providing a passage adapted to communicate with the engine cylinders, means for controlling the sup-ply of a mixture of fuel and air to said passage including a manually operable throttle valve and an air inlet valve adapted to be opened in response to suction in the engine cylinders, a dash pot, a chamber communicating .with said dash pot, means for supplying fuel under pressure to said chamber including a plunger in said dash pot, operative connections between said plunger and airrvalve, and means for supplying fuel from said chamber to said passage including a piston movable in said chamber in response to movement of said air valve and at a lesser rate of speed.

26. In a. fuel system for internal combustion engines, in combination, means providing a passage adapted to communicate with the engine cylinders, means for controlling the normal supply of a mixture of fuel and air to said passage including an air inlet valve, a chamber, a dash pot having a plunger movable therein, means adapted to provide communication between said chamber and passage, a fuel conduit connecting said chamber and dash pot, operative connections between said valve and plunger whereby movement of the former causes the latter to move to subject fuel in said chamber to pressure, and means responsive to said movement of said valve and adapted to act thereafter to maintain fuel in said chamber under pressure for a predetermined period to cause fuel to be supplied to said passage.

27. Ina fuel system for internal combustion engines, in combination, means providing a passage adapted to communicate with the engine cylinders, means for controlling the normal supply of fuel to said passage including a throttle valve,vmeans for controlling a supply of air to saidpassage including an air valve, a pair of dash pots each having a plunger movable therein, a chamber communicating with said dash pots, means providing communication between said chamber and passage, operative connections between said air valve and one of said plungers and between said throttle Valve and the other plunger whereby movement of said valves causes said plungers to move to subject fuel in said chamber to pressure, and means responsive to said movement of said valves and adapted to act thereafter to maintain fuel in said chamber under pressure for a predetermined period tocause fue] to be supplied to said passage.

WILFORD H. TEETER.