US1939431A - Charge forming device - Google Patents

Description

- Dec. 12, 1933.

F. E. ASELTINE CHARGE FORMING DEVICE Filed Jan. 2, 1951 see-E I 4 L 1 H 2,59 was Fred 51752711712.

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Patented Dec. 12, 1933 PATENT OFFICE CHARGE FORMING DEVICE Fred E. Aseltine, Dayton, Ohio, assignor to Delco Products Corporation, Dayton, Ohio, a corporation of Delaware Application January 2, 1931.

Serial No 506,096

Claims. (01. 26134) This invention relates to charge forming devices for internal combustion engines. While the invention is particularly adaptable to the type of charge forming device disclosed in the application 5 of Fred E. Aseltine et al., Serial No. 360,404, filed May 4, 1929, and in fact has been shown herein as embodied in that type .of charge forming device, it will be understood that the invention is applicable to substantially any type of charge forming device in which the mixture passage extends in a generallyhorizontal direction.

It is the principal object of the invention to prevent the puddling of fuel in the mixing chambet and in the air inle; which supplies air thereto, particularly during operation at idlingor relatively low speeds, and it is a further object to improve the operation of the engine when idling. These objects are accomplished according to the present invention, by the provision of relatively narrow grooves in'the floor or between the walls of the mixing chamber, which grooves begin at a point relatively close to the air chamber which supplies air to the mixingchamber orchambers and terminate relatively close to the throttle which controls the flow of mixture from the mixing chamber 'orJchambers. When the throttle is in a nearly closed position, as when the engine is idling, it will be obvious that the air passing through'the mixing chamber flows at a considerable velocity through these grooves which are open, while the outlet from the. mixing'chamber proper is closed by the throttle. This current of air moving at relatively high velocity sweepsjthe fuel outof the mixing chamber past the throttle and so to the engine intake. ports, preventing the puddling of fuel on the floor of such chamber or the formation of a film on the walls'ihereof, and in so doing; prevents the accumulation of enough fuel in the. mixing chamber to flow from said mixing chamber into the air supply chamber which supplies air thereto.

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

In the drawing:

Fig; 1 is a longitudinal section through a charge forming device constructed according to the present invention.

Fig. 2 is a detail section on the line 2--2 of F l. l

Fig. 3 is a fragmentary detail section showing the highspeed fuel supply. l

Fig. 4 is a fragmentary side elevation with certain parts broken away to show other parts in section.

Figs. 5. and 6 are detail views of a modified form of the invention.

The device in which applicant's invention is embodied, comprises a mainair manifold 10, having three outlet branches, the middle branch 12 being shown herein. Each outlet branch communicates with one of the ports of a multicylinder engine and each is provided with an attaching flange for securing the manifold to the engine block in the usual manner, while a flange 14 is provided at the manifold inlet to which the car buretor unit is secured.

The carburetor unit comprises a main housing 16,.having an attaching flange 18 attachable to ihe flange 14 by screws 20. An air inlet coupling 22 is secured in an opening in the upper wall of the housing in any suitable manner and may be connected with an air cleaner, if desired. A casting 24 in which the fuel supplying passages are formed, is secured to the bottom wall of the main housing by screws 26 and a fuel bowl 28 isheld tight against the bottom of the housing by any suitable means such as a screw 30 screwed into the casting 24. Fuel is conducted from a main source of supply to the bowl 28 bymeans not shown, and a substantially constant level of fuel is maintained in the bowl by a float 31 operating in the usual way.

Fuel flows from the bowl to a plurality of fuel nozzles 32 and 34, there being a pair of these nozzles in each of a plurality of primary mixing chambers 36, the construction of which will'be more fully described later. The nozzle 32' supplies fuel at all times and under all operating conditions, while the nozzle 34 is effective to supply fuel only after the throttle has been opened a predetermined distance and the engine is operating at relatively high speed. Separate fuel passages supply the nozzles 32 and 34 with fuel, the nozzle 32 being supplied by thever'tical passage 38 having a fixed opening 40 at its lower end and communicating at its upper end with a fuel chamber 42, formed in the casting 24 and communicating with all of the nozzles 32.

The high speed nozzles 34 are supplied with fuel through an orifice 44, controlled by a valve 46 operated as later described. The port 44 admits fuel to a channel formed in the casting and indicated in its entirety by the reference character 48, the flow of fuel through such channel being automatically controlled by a valve 50 in a manner fully described in the above mentioned 0 application and being entirely immaterial so far'as the present invention is concerned. The channel 48 communicates with the horizontal channel 52 in the casting 24 and communicates with all of the nozzles 34. Each fuel nozzle 32 is provided with a main fuel outlet 54 in its top and a secondary fuel outlet comprising holes 56 and 58 in the vertical wall of the nozzle near the bottom of the mixing chamber. At idling and low speeds, the suction is sufficient to lift fuel only to some point between the orifices 56 and 58 and the top of the nozzle at which time fuel flows from the orifices 56 and 58 by action of gravity, but on intermediate and high speeds, the suction is enough to lift the fuel from the main outlet 54. The nozzles 32 and 34 are provided with restrictions 60 and 62 respectively, for controlling the rate of fuel flow therethrough. The primary mixing chambers 36 deliver a primary mixture of fuel and air to primary mixture passages 64,

which convey the primary mixture to secondary mixing chambers 66, formed in the outlet branches of the manifold, as more fully pointed out later. The connection between the primary mixing chambers and mixturepassages 64, is restricted at 68 to reduce the velocity of flow past the nozzles and air passages 70 supply air to said mixture passages immediately in advance of the restrictions 68.

The primary mixture passages 64 are parallel and close together as indicated in Fig. 2, and when the carburetor is secured to the manifold, these passages register with conduits which, convey the primary mixture to the mixing chambers 66, as

fully disclosed in the above mentioned application. g 1

A single throttle valve 72, which extends across all of the primary mixture passages, controls the flow therethrough and is provided with grooves '14, which register with the mixture passages. The throttle is operated in the manner very briefly. described later. The middle mixture passage communicates with a tube '16, fixed in the middle branch-of the manifold and constituting one of the primarymixture conduits above referred to, which convey the primary mixture to theimixing chamber 66. All of the air admitted to the carburetor flows through the coupling 22 and is controlled by a suction operated valve 78, normally heldagainst its seat by spring 82, received between the valve and a flange 84, projecting from a sleeve 86, slidable on a fixed sleeve 88, which is secured in the housing and guides the valve stem 90 as described in the above mentioned application. The sleeve 86 is adapted to be lifted-by a lever 92, through the medium of connections not shown herein, to holdtheair valve closed and facilitate starting, at which time asmall quantity of air is admitted through slots 94, formed in the surfaceof the valve '78.

The valve "'78 admits air directly to a main air chamber 96, from which the air flows to the primary mixing chamber through anopening 98, which communicates with a primary air chamber 99, while air is admitted to the secondary mixing chambers through a passage 100, which connects with the inlet of the manifold. The flow of air through thisipassage is controlled by a manually operable throttle 102 and a'suction operated valve 104, secured respectively, to shafts 106 and-108, and rotatably mounted in the housing; I

The operating connections for these valves form no part of the present invention and will not. be described in detail herein. Briefly, the

operation of the device.

valve 102 is operated by the primary throttle '72, by a lost motion connection designed to permit an independent movement of the throttle '72 without accompanying motion of the valve 102, the operating connections generally being designed to allow the throttle to move to a position corresponding to a vehicular speed of 20 to 25 miles per hour on the level before the valve 102 begins to move. Later, said valve and throttle mnva simultaneously.

Opening movements of the valve '78 are retarded to prevent fluttering of the valve and to enrich the mixture to some extent during the acceleration period. To this end, the valve stem 90 has secured to its lower end a dashpot piston 110, whichslides in a cylinder 112, supplied with fuel from the fuel bowl by leakage around the piston.- The form of dashpot employed is not material and any conventional dashpot may be used.

The suction. operated valve 104 is also provided with a dashpot to retard its opening movement so as to restrict the admission of air through the air manifold during the acceleration period. This dashpot is operated through a train of operating connections shown in Fig. 4, comprising the arm' 114 secured to the shaft 108, the link 116 connecting the arm with the lever 118,which, at its opposite end, is connected to rod 120, secured to the piston of a dashpot which is not shown. The specific form of the dashpot is entirely immaterial so far as the present invention is concerned and is only described herein to aid in an understanding of the general It has been found that if the valve 104 is permitted to open freely, the air admitted to the secondary mixing chambers would cause a leaning of the mixture during the acceleration period,'but by retarding to some extent the opening of the valve andthus restricting the admission of air during the acceleration period, this difficulty is avoided, as pointed out more fully in the abovementioned application. A pump is also provided which is not shown herein, but is adapted to deliver additional fuel to the primary mixture passages through the passages 122, which terminate adjacentthe throttle 72, asshown in Fig. 1.

It has been found that in a device of the character described above, there is a tendency for fuel to collect in the primary air chamber 99, and on the floor of the primary mixing chambers 36, when the throttle is in a substantially closed position during idling .and under some other operating conditions when the velocity through the primary mixing chambers is relatively low. When fuel collects in this manner, the supply of fuel to the engine intake ports is irregular because the fuel will collect andform a film on the walls which, when the accumulation offuel becomes sufficiently great, will be broken up and fuel drawn into the ports in relatively large particles. Since there is a relativelysmall quan-' tity of fuel being supplied to the ports during idling, this irregularsupply of additional fuel considerably interferes with the engineoperation at such time and it is the purpose of the present invention to provide means which will effectively prevent the accumulation of the fuel described and which will not otherwise interfere with the proper operation of the device.

' The form of the invention shown in Figs. 5 and 6 is probably the preferred form of the invention and, therefore, will be-first described.

In this form of the device, each primary mixing "distance from the air chamber 99, where the ends of the groovesare closed as indicated by the reference character 132. The fuelnozzles extend upwardly through the bottom of the mixing chambers above'these grooves. The throttle is slightly cut away, as indicated at 134, to register with each of these grooves so that as the throttle is moved toward open position, the grooves are open and subject to engine suction before the ing backwardly into the said air chamber.

outlets from the mixing chambers proper are openedf Therefore, when the throttle is closed in its idling position, there will be a relatively high velocity of flow through the grooves. This high velocity flow ofair will sweep any fuel whiehtends to collect at the bottom of the mixing chambers into the mixture passages beyond the throttle. It has been found by closing the anterior ends of the grooves, as indicated, and not extending the grooves all of the way to the air chamber 99,fuel will be prevented from flow- It is possible, however, to use grooves which extendall the way to the chamber 99, in which event any fuel which tends to accumulate in said chamber will be carried out through the grooves in question because the velocity of flow through such grooves is higher when the throttle is in closed or nearly closed position, t en through the mixing chambers proper.

It will be understood that the fuel which is supplied during the idling operation of the engine through the orifices 56 and 58 is delivered directly into the grooves above described, so that the idling fuel is swept through such grooves and into the primary mixture passages 64 by the high velocity air current flowing therethrough and there will be no tendency for such fuel to collect as might be the case if the grooves were not provided. In such event, the velocity of flow past the orifices 56 and 58 is less than when the grooves are provided and there is some tendency for the fuel delivered through these orifices to form a film on the walls of the primary mixing chambers. If fuel forms a film as described, it is backed up by the air stream in a somewhat irregular manner, as referred to earlier in the specification and the idling mixture is, therefore, made homogeneous in its fuel content, which results in irregular operation of the engine. By

the provision of the grooves, whichare so positioned that the idling fuel is delivered directly thereto, this irregularity of engine operation during idling is avoided.

In the form of the device shown in Figs. 1 and 2, it will be noted that instead of usingthe grooves above referred to, the applicant has provided passages 136, formed in the bottom wall of the housing below the floor of the mixing chambers. These passages are so constructed and terminate in such position relative to the throttle, that a very high veloctiy of flow is maintained therethrough and any fuel which, because of eddy currents or for any other reason, tends to accumulate in the chamber 99, is drawn outwardly through the passages in question and conveyed back into the main mixture stream.

Also because of the position of these passages relative to the outlet ends of the primary mixing chambers, it will be clear that the high velocity of flow therethrough creates an aspirating action at the outlet ends of the primary mixing chambers, which aspirating action tends to increase the velocity of flow through such mixing 1 chambers and thus tends to prevent the puddling of fuel on the bottom wall thereof.

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.

What is claimed is as follows:

1. -A charge forming device for internal combustion engines, comprising, in combination, a

mixing chamber lying in a substantially horizontal plane, fuel and air inlets therefor, a throttle controlling the flow of mixture therefrom, and means for preventing accumulation of fuel on the floor of the mixing chamber, said means comprising a groove formed in the floor of the mixing chamber into which fuel collecting on the walls may flow by action of gravity, and subject to engine suction whenever the engine is running.

2. A charge forming device for internal combustion engines, comprising, in combination, a mixing chamber lying in a substantially horizontal plane, fuel and air inlets therefor, a throttle posterior to the mixing chamber and controlling the flow of fuel therefrom, and means preventing accumulation of fuel on the floor of the mixing chamber, said means comprising a groove formed in the floor of said mixing chamber into which fuel collecting on the walls may flow by action of gravity and terminating adjacent the throttle.

3. A charge forming device for internal combustion engines, comprising, in combination, a mixing chamber lying in a substantially horizontal plane, fuel and air inlets therefor, a throttle controlling the flow of mixture therefrom, an air supply chamber anterior to the mixing chamber and supplying air thereto, and means for preventing accumulation of fuel in the air chamber, said means comprising a groove in the floor of the mixing chamber for collecting surplus liquid fuel, said groove being open so that fuel air supply chamber anterior to the mixing chamber for supplying air thereto, and having its floor at a lower level than that of the mixing chamber, and means forfpreventing accumulation of fuel in the air chamber, said means comprising a groove in the floor of the mixing chamber terminating adjacent the air supply chamber and closed at itsanterior end.

5. A charge forming device for internal com bustion engines, comprising, in combination, a

mixing chamber lying in a substantially horizontal plane, means for supplying fuel and airy thereto, a groove in the floor of the mixing chamber, and a corresponding groove in the throttle, whereby during opening movement of the throttle the groove in said throttle first registers with the groove in said mixing chamber to communicate the engine suction to saidgroove before the outlet .of themixing-chamber proper -of the opening movement of the throttle so that the groove inthe floor of the mixing chamber will be subjected to engine suction beforethe mixing chamber proper, and means for delivering fuel directly to the groove when the engine is idling.

7. A chargevforming device for internal combustion engines, comprising, in combination, a

mixing chamber lying in a substantially horizontal plane, a throttle controlling the outlet from the mixing chamber, a groove'in the floor of the mixing chamber adapted to prevent accumulation of fuel on said iioor during normal engine operation and adapted to be subjected to engine suction before the mixing chamber proper so as to supply fuel for idling, and a fuel nozzle forv supplying fuel to the mixing chamber having a fuel feeding orifice in its wall delivering fuel directly to the groove. M V

,8. A charge forming device for an internal combustion engine, comprising-a secondary mixing chamber, a primary mixing chamber, means,

for supplying fuel and air to the primary mixing chamber, a primary mixture passage connecting the primary and secondary mixing chambers,

tle' before the primary mixing chamber proper.

9. A charge forming device for internal combustion engines, comprising in combination, a mixing chamber lying in a substantially horizontal plane, an air inlet therefor, a fuel nozzle projecting upwardly into the mixing chamber, a throttle controlling the flow of mixture therefrom, and means for preventing accumulation of fuel on the floor of the mixing chamber comprising a groove formed in the floor of said chamber adapted to collect liquid fuel deposited on the wall thereof,fsaid groove embracing the fuel nozzle and being Wider than the outer diameter of the nozzle.- 10. Acharge forming device forv internal combustion engines, comprising in combination, a mixing chamber lying in a substantially horizontal plane, an air inlet therefor, a fuel nozzle projecting upwardly into the mixing chamber, a throttle controlling the flow of mixture therefrom, and means for preventing accumulation of fuel on the floor of the mixing chamber comprising a groove formed in the floor of said chamber adapted to collect liquid fuel deposited on the wall thereof, and being subject to engine suction in all positions ofthe throttle, said groove embracing the fuel nozzle and being wider than the outer diameter of said nozzle.

FRED E. ASELTINE.

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