US1900685A - Charge forming device - Google Patents

Description

Mrch 7, 1933. F E, AsEL'nNE 1,900,685

CHARGE FORMING DEVICE Filed Sept. 7, 1929 Patented Mar. 7,

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man n. AsEL'rINE. or DAYTON, omo. AssIeNon fro DELcO raonuc'rs, ooaronynon,

or ANDEnsoN, INDIANA, A CORPORATION or' DELAWARE CHARGE FORMING Dnvrcn t .Application aled September 7, 1929. f Serial No. 391,059.

This invention relates tochargeformin devices for internal combustion engines, an

more particularly to devices of this character which comprise a plurality of primary carburetors which .deliver a primary mixture of fuel and air to a plurality of secondary mixing chambers located adjacent the engine intake ports, and in which the primary mixture is mixed with addition-al air under tain operating conditions.

A device of this character is disclosed in the copending application of Fred E. Aseltine, Vilfoi-d l-l. 'leeter and CarlH. Kindh Serial No..288,683, tiled June 10, 1928, to

which reference may be had for a full disclosure of the device shown herein.

It is Athe main object of the present invention to provide a device of the character above referred to, having improved means for controlling the proportions of the mixture during operation following any opening of the throttle valve, and more particulai-ly, to provide means for preventing too great enrichment of the mixture when the throttle is'opencd and the engine is already running at relatively high speed.

It is a further more specific object of the invention to provide improved means for retarding the opening vmovements of the main and auxiliary air valves which is of simplel design, comprises few moving parts' and is effective to retard the opening of the valves to the same extent, regardless of the position the valves occupy when such Opening movement takes place. Y

In earlier devices of this character means have been provided retarding the opening l m ement of both the main and auxiliary air 'v ves on any opening movement of the ttle. It is desirable to render .such re-v ta ing means ineffective when the throttlev lis open and t speeds becau ,reduction of the Openin of the air valveiinder sucliopei'a 'ng conditions would cause an enrichm n the 'mixture which is not desirable 'at uch time.A According tothe present invention, the `retarding means for both the auxiliar airfvalve becoines ineffective'i by'a single evice when the valves are opened cer-` e engine is running at high` main air'valve vand, the

under the o erating conditions referre l to and both va ves are permitted to open relatively freely at this time.

Further objects and advantages of the present invention will be apparent from the cal section on the line 2-2 of Fig. 1.

The device disclosed comprises aina-in air.

manifold l0, liavinr three outlet branches, the middle branch E.l2 being shown herein. Each of these branches communicates, with one of the intake ports 14 of-a multicylinder engine. The outlet branches are each provided with an attaching flange 16 for-securing the manifold to the engine block in the usual manner, and a flange 18 to which the carburetor unit is secured.

The carburetor unit comprises amainhOus- A ing 20, having an attaching flange 22, adaptedV to be secured to the flange 18^by"screws24. An air inlet coupling 28 is secured in position to register with an opening in the upper wall of the housing 20, in any suitablejway, v

with an air cle'anen if desired. A casting 30, in which the "pas-l sages supplying fuel to the nozzles are and may' be connected formed, is secured by screws to the lower wall of housing 20, and a sheet metal fuelbowl 32 is held tight against an annular shoulder 34 on the housing 20 byany suitable means. Fuel is conducted from a? main source of supply to the fuel bowl t rough a conduit not shown) and the flow of fuel to the bowl is controlledby a floatl which is not illustrated but operates in the usualmanner to maintain a substantially constant level of fuel therein, as described insaid earlier case.

Fuel flows from the bowl 32 to a plurality of primary fuel nozzles 38,1One of which is 'locate'dineachgof the primary mixing chainbers 40, the construction of whichis briefiy described hereinafter. The fuel condult between the fuel bowl and the nozzles com.-

prises the vertical fuel passage 42 communieating at its ,upper end with the horizontal fuel canal 44, which connects with each of the nozzles 38 through an orifice 46. Fuel is admitted from the fuel bowl to the passage 42 at all engine speeds, through a fixed metering orifice 48 and at high speeds additional fuel is admitted through an orifice 50 controlled by a valve 52, operated in the manner set forth in the above mentioned application. This operating means forms no part of the present invention and need not be described further herein.

Fuel is lifted from the fuel bowl through the above described fuel passages and nozzles 38 to the primary mixing chambers by the suction therein. Opening movements of the throttle cause a reduction `in mixing chamber suction which might permit the fuel column to drop sufficiently to cause a temporary fuel starving of the engine unless means are provided to prevent this action. For this purpose a check valve 54 is provided in an enlarged chamber 56 at the junction of the channels 42 and 44, and on reduction of mixing chamber suction, seats on the bottom of the chamber, preventing downward flow of fuel.-

Each primary fuel nozzle is provided with a main fuel outlet 58 in the top of the nozzle and a secondary fuel outlet comprising two orifices 60 and 62 in the vertical wall of the nozzle near the bottom of the mixing chamber. At relatively high speeds, the mixing chamber suction is sufficient to lift fuel from the main outlet as well as from orifices 60 and 62. At idling, or low speed operation under load, however, the suction is enough to lift fuel only to some point between the top of the nozzle and the orifices 60 and 62, fuel flowing from these orifices by the action of gravity under such operating conditions. Each nozzle is provided with a restricted fuel metering orifice 63. The primary mixing chamber comprises the enlarged anterior ends of the primary mixture passages 64, which are parallel to each other and close together, as indicated in Fig. 2. When the carburetor is attached to the manifold, these passages register with conduits which convey the primary mixture to the secondary mixing chambers, as fully disclosed in the application l above referred to. Restrictions 66 separate the primary mixing chambers from the remainder of the mixture passages to reduce the velocity of flow past the fuelfnozzles for a purpose fully set forth in the abovek mentioned copending application.

A single throttle valve 68, which extends across all the primary mixture passages, controls the flow therethrough and is provided with grooves 70, which register with said 1,ooo,ess

fold branch 12. This tube constitutes one of the primary mixture conduits above referred to and conveys the primary mixture to the secondary mixing chamber located in the middle branch of the manifold.

Nearly all of the air entering the carburetor fiows through the inlet coupling 28 and is controlled by the main air valve 74, normally held against a seat 76 by a spring 78, received between the valve and a flange 80, projecting from a sleeve 82, slidably mounted on a stationary guide sleeve 84, fixed in the housing 2Q, and serving also as a guide for the stem 86 to which the air valve is secured. When it is desired to choke the carburetor to facilitate starting of the engine, the flange 80 is adapted to be lifted by means not shown herein, but fully described in the above application, unt-il the upper end of the sleeve 82 engages the air valve to hold it closed. Sufficient air to carry the starting fuel from the nozzles to the intake ports is admitted through an elongated slot 87, formed in a plate 88, secured to the housing 20, as shown in Fig. l.

The valve 74 admits air to the air chamber 90, from which air flows to the primary mixture passagesthrough an orifice 92 in the bottom of the'air chamber and to the secondary mixing chambers through a passage 94, which connects with the inlet of the manifold l0. The flow of air through this passage is controlled by a manually operable throttle 96, secured to a shaft 98, rotatably mounted in the main housing and by a suction operated valve 100, secured to a shaft 102, also rotatably mounted in the main housing.

The operating connections for the two throttle valves constitute no part of the present invention and are not described herein, it being sufficient for the purposes of this disclosure to describe briefiy the mode of operation of these Valves. The primary throttle is connected to the main air throttle 96 by a lost motion connection, which permits a predetermined movement of the primary throttle independent of the throttle 96, and is capable of adjustment. It is generally adjusted so that the primary throttle is movable without accompanying movement of the air throttle until the former reaches a position corresponding to a vehicular speed of approximately 15-20 miles per hour on the level. On further opening of the primary throttle, the air throttle is moved simultaneously therewith.

Onvopening of one or both o f the throttle valves, the suction in the air chamber 9.0.is

increased, and the valve 74 is opened to 'admit additional air and increase the quantity supplied to the engine. The opening of this valve is retarded to prevent fluttering of the valve and to restrict the admission of air to some extent whenever the throttles are open. For this purpose a dashpot is provided comprising a cylinder 104 formed in the casting 30 and receiving fuel from the reservoir 32, and a piston 106 secured to the lower end of the .air valve stem by any suitable vmeans. The resistance of this dashpot is controlled by means comprising an auxiliary ,cylinder 108 formed in casting 30 and closed at the lower end by a detachable plate 110, which also forms the bottom of the cylinder 104,

a suitable gaslret being provided between the plate and the casting 30 to preventleakage. The cylinder 10d is connected with the cylinder 108 by a passage 112, bored in the casting 30 and communicating with the cylinder 104 at the bottom and cylinder 108 at the top, as shown in 1. vlhe passage 112 connects with the cylinder 108, through a projecting surface 114 formed on the top of the cylinder 108, and a piston 116, which is slidably received in the cylinder 108, is normally held against the proiection 114 by a spring 118 received between the piston and the plate 110. `llt will be clear, therefore, that until the y piston 116 is moved to open the passage 112 the only escape of fuel from the cylinder 104 is by leakage around the piston 106 and resistance to opening of the air valve is high. When the pressure on the fuel in cylinder 104i is enough to disengage the piston 116 lrorn surface 114 the resistance of the dashpot is much reduced because the fuel can escape 'from the cylinder 104 through passage 112 and orifices 120 jformed inthe piston 116 and through a restricted passage 122, leading from the cylinder 108 into another cylinder which forms part of the dashpot controllingmovement of the auxiliary air valve in the manner hereinafter described.

' As pointed out hereinbefore and fully shown and described in the above mentioned.. earlier application, the valve 100 is opened by engine suction whenever the air throttle is opened. According to the present invention, the o ening movements of this valve are retarded Ey means of a dashpot which is rendered relatively ineffective to accomplish this result when the auxiliary air valve is opened following an opening movement of the throttlewhen the engine is runningatrelatively high speed. To accomplish this result,

' the shaft 102 on which the auxiliary air valve is mounted, has secured to one end thereof outside the main housing, an arm 130, which is pivotally connected by a pin and slot connection 132 to a link 134, the lower end of which is pivotally connected at 136 to a piston rod138, yieldingly connected in a manner hereinafter described to a piston 140 which is slidably received in a. cylinder 142, with which the passage 122, above rein any desirable way to a tube 144, having a closed upper end through which the rod138 extends. The tube 144 is also closed at the lower end b ascrew cap 146 and slidably received'wit in the tube is an enlarged head 148,- formed on the lower end of the piston rod 138, While received between the said head and the upper end of the tube is avhelical spring 150.

On any opening movement of the valve 100, the piston rod 138 is lifted and its movement is retarded relatively slightly by the action of the spring 150, which must be compressed as the valve is opened, and by the action of the dashpot piston 140, the movement of which is controlled by the rate of dow through the restricted passage 122, and also by the auxiliary piston 116, which must be moved out of engagement with the surface 114 before the piston 140 can move upwardly.

The latter piston is moved by the main air valve as; previously described.

W hen the main and auxiliary air valves are opened relatively slowly following such openings of the throttle as do not produce any great increase in suction on the valves the piston 116 is not disengaged from the surface 114 and fuel escapes from the dashpots only by leakage past the pistons, but when the valves 74 and 100 are opened very suddenly and by considerable force, as'when the throttle is opened and the engine is already running rapidly, the ed'ect of the dashpots controlling their motion is largely eliminated. As the main air valve is opened the piston 116 is moved out of engagement with the surface 114 so that the retarding eliect of the piston on valve 74 is largely nullied and upward movement oil the piston 140 retarded only by the limited rate of fuel dow through the passage' 122, which may he of whatever size proves most desirable.

Moreover, when the valve is operated under the operating conditions described, the fierce edective to open such valve is great enough to collapse the spring 150 permitting the piston rod 138 to move relative to the piston 140, which will remain relatively stationary until the pressure of the spring becomes great enough to overcome the resistance odered to upward movementfof piston 1410, alter which it will be slowly moved upwardly by the spring 150 until the part-s assume the normal position shown in Fig. 1. After any opening movement of the valves 7 4 and 100 is completed the piston 116 will also be moved to its normal position so that following such movement the parts will assume their normal positions after a slight interval of time, and

'the resistance to any opening movement of the throttles will always be the same whatthe action of the auxiliary dashpot is controlled by the main air valve through the medium of the piston 116 and the latter forms a valve mechanism operating to re ulate the resistance to opening movement o both air valves.

The secondary mixing chambers are identical in construction and each comprises a Venturi tube 160, which is held in position adjacent the outlet of the primary mixture conduits in the manner fully disclosed in the above mentioned application. As this construction forms no part of the present invention, it will not be described in detail herein.

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 a kmixing chamber, fuel and air inlets therefor, a throttle controlling the flow of mixture therefrom, main and auxiliary air valves controlling the admission of air to the mixing chamber a plurality of, means for retarding the opening movements of these air valves and pressure o erated means for regulating the effect of a l said retarding devices.

2. A charge forming device for internal combustion engines comprising a mixing chamber, fuel and air inlets therefor, a throttle controlling the flow of mixture therefrom, main and auxiliary air valves controlling the admission ofl air to the mixing chamber, a plurality of dashpots for retarding the opening movements of said valves and a pressure operated device for regulating the effectiveness of all of said dashpots.

3. A charge forming device for internal combustion engines comprising a mixing chamber, fuel and air inlets therefor, a throttle controlling the How of mixture therefrom, main and auxiliary air valves controlling the admission of air to the mixin chamber, a plurality of dashpots for retar ing the opening movements of said valves and aA single means for regulating the effectiveness of all of said dashpots.

4. A charge forming device for internal combustion engines comprising a mixing chamber, fuel and air inlets therefor, a throt- 'tle controlling the How of mixture therefrom, an auxiliary air valve controlling the admislsion of air to the mixing chamber, a dashpot comprising a piston resiliently connected to the auxiliary air valve for retarding its opening movement, and valve means comprising an auxiliary cylinder and piston valve slidable therein controlling the retarding effect of said dashpot.

5. A charge forming device for internal combustion engines comprising a mixing chamber, fuel and air inlets therefor, a throttle controlling the iiow of mixture therefrom, main and auxiliary air valves controlling the admission of air to the mixing chamber, dashpots for retarding the movement of said valves, and a single valve means for controlling the outlet of one dashpot and the inlet of the other, whereby said valve regulates the retarding effect of both said dashpots. l

6. A charge forming device for internal combustion engines comprising a mixing chamber, fuel and air inlets therefor, a throttle controlling the iow of mixture therefrom, main and auxiliary air valves controlling the admission of air to the mixing chamber, dashpots for retarding the opening movement of said valves, and valve means controlling the outlet of one dashpot and the inlet of another, said valve means comprising an auxiliary cylinder with which said inlet and outlet communicate and a piston slidable therein.

7. A charge forming device for internal combustion engines comprising a plurality of primary mixture passages, means for supplying fuel and air thereto, a plurality of secondary mixing chambers to which said passages deliver a primary mixture of fuel and air, a main air valve controlling the admission of air to said passages and to said secondary mixing chambers, an auxiliary air valve also controlling the admission of air to said secondary mixing chambers, dashpots for controlling the admission of air to said valves and a common means for regulating the effect of both said dashpots.

In testimony whereof I hereto afiix my signature.

FRED E. ASELTINE.

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