US1853011A - Charge forming device - Google Patents

Description

A ril 5, 1932.

F. E. ASELTINE 1,853,011 CHARGE FORMING DEVICE Filed April 30, 1929 Z 72 V 4a 22 /8 24 k 76 I /0 74/! v I V 42- Patented Apr. 5, 1932 UNITED" STATES FRED E. ASELTINE, OF DAYTON, OHIO, ASSIGNOR '10 DELCO PBODUCTS'CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE PATENT OFFICE CHARGE ronmne DEVICE ing chamberswhile receivingadditional airunder certain operating conditions through branches of an air manifold having a single air inlet passage controlled by a single main air throttle.

An example of a charge forming device of this character is disclosed in the copending application of Fred E. Aseltine et a1. Serial No. 221,371.,and that of Wilford H. Teeter,

Serial No. 221,372 both filed on September 22, 19.2 I r 'In all of the earlier devices of the character illustrated in the above applications, various means have been provide to control the supply of fuel and air under different operating conditions so as to form a mixture of the desired proportions under all circumstances, and it is the principal object of the presentinvention to provide simplified and improved means for regulating the mixture proportions on opening movements of the throttle under various operating conditions in order to provide a mixture of more nearly correct proportions than has been heretofore possible under such operating conditions.

It is a furtherobject of the present invention to regulate the admission of air in accordance with the manifold vacuum and more particularly to utilize the vacuum posterior to the throttle to control the action of the air valve duringopening movements of the throttle.

i 7 According to this invention, these objects are accomplished by providing a dash pot fdr controlling the opening movement of the main air valve and a valve, operatedin accordance with the suction in the intake manifold posterior to the throttle, for controlling the escape of liquid from the dash pot and thus regulating the resistance offered by said dash pot to movement of the valve.

Further objects and advantages of the present invention will be apparent from the following description, reference being had 1 to the accompanying drawings wherein a pre ferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal section through a charge forming device embodying the present invention and oneof the associated engine intake ports.

Fig. 2 is a transverse section on the line 2-2 ofFig. 1. i

Fig. 3 is a fragmentary, transverse section on the line 33 of Fig. 1.

Fig. 4 is a detail elevation of the throttle operating connections.

Thedevice disclosed comprises a main air manifold 10 having three outlet branches the middle branch 12 being'shown herein. liiach of;these branches communicates with one of the intake ports 14: of a multicylinder engine. These outlet branches are each provided with an attaching flange 16 for securing'the manifold to the engine block in the usual manner. Adjacent the inlet of the manifold is provided a flange 18 to which the main carburetor unit is adapted to be attached, as shown in Fig. 1.

The carburetor unit comprises a main housing 20 having an attachin flange 22, adapted to be secured to the ange 18 by screws 24. An air inlet horn 28 is secured in position to register with an opening in the upper wall of the housing 20 in any suitable way; A casting 30, having certain dash pot chambers and fuel passages formed therein is secured by screws to the lower wall of the 90 housing 20 and a sheet metal fuel bowl 32 is held tight against a shoulder 34 on said housing by any suitable means. Fuel is conducted from a main source of supply to the fuel bowl through a conduit, not shown herein,

' and the flow of fuel to the bowl is controlled by a float 36 operating in the usual manner to maintain a substantially constant level of fuel therein.

Fuel flows from the bowl 32 to a plurality of primary fuel nozzles 38, one of which is located in each of the primary mixing chamhere 40, the construction of which is briefly described hereinafter. The fuel conduit between the fuel bowl and the nozzles comprises a vertical fuel passage 42 communicating at its upper end with a horizontal fuel canal 44, which connects with each of the nozzles 38 through orifices 46. Fuel is admitted from the fuel bowl to passage 42 at all speeds through a fixed metering orifice 48 and at high speeds additional fuel is admitted through an orifice 5O controlled by a valve 52 in the manner set forth in the above mentioned applications.

Fuel is lifted from the fuel bowl through the above described fuel passages and nozzles 38 to the mixing chambers 40 by the suction therein. Closing movements of the throttle cause a reductionin mixing chamber suction, which might permit the fuel column to drop sufficiently to cause a temporary fuel starving of the engine unless means were provided to prevent such action. For this purpose a check valve 54 is provided in an enlarged chamber 56 at the junction of channels 42 and 44, and on reduction of mixing chamber suction seats on the bottom of this 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 sutficient to lift fuel from the main fuel outlet as well as from the holes 60 and 62. At idling and low speed operation under load, however, the suction is enough to lift fuel only to some point between the top of the nozzle and orifices 60 and 62, fuel then flowing from these orifices only by action of gravity. Each nozzle is provided with a restricted fuel metering orifice 63. The primary mixing chambers 40 comprise the enlarged anterior ends of primary mixture passages 64, which are parallel to each other and close together, as indicated in Fig. 2, and 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.

copending application referred to.

A single throttle valve 66, which extends across all the primary mixture passages, controls the flow therethrough and is provided with grooves 68 which register with said mixture passages. This throttle is operated by means shown in Fig. 4, and is briefly described hereinafter. The middle primary mixture passage connects with a tube 7 O fixed in the manifold branch 12, which conveys the primary mixture to the secondary mixing chamber in that manifold branch.

Substantially all the air entering the carburetor flows through the air horn 28, controlled by a main air valve 72, normally held against a seat 74 by a spring 76, received between the valve and a flange 78, projecting from a sleeve 80, slidably mounted ona stationary guide sleeve 82, fixed in the housing 20, and serving as a guide for the stem 84, to the upper end of which the valve 72 is secured.

When it is desired to choke the carburetor to start the engine, the flange 78 is adapted to be lifted by an arm 86, as fully described in the above mentioned applications, until the upper end of the sleeve 80 engages the valve 72 to hold it against its seat. Sufiicient air to carry the starting fuel from the nozzles to the intake ports is admitted through an elongated slot 88, formed in a plate 90, secured to the housing 20, as shown in Fig. 1.

The valve 72 admits air to a main air chamber 92 from which air flows to the primary mixture passages through an orifice 94 in the floor of the air chamber and to the second ary mixing chambers through a passage 96, which connects with the inlet of the air manifold 10. A manually operable throttle 98, secured to a shaft 100, controls the flow of air through the passage 96, said throttle being operated through the medium of the primary throttle by means of connections which will now be very briefly described. These 0perating connections are fully disclosed in the earlier copending cases above referred to and it is sufficient to say herein that the primary throttle is operated by means of an arm 102, secured in any desirable manner to a spindle 104, projecting from one end of the primary throttle, and connected by means of a lost motion connection indicated in its entirety by the reference number 106, to an arm 108, secured to one end of the shaft of the main air throttle. This construction permits a limited movement of the primary throttle independent of the air throttle 98, permitting the said primary throttle to be partially opened while the air throttle remains completely closed. The lost motion operating connection is capable of adjustment and is generally adjusted so that only the primary throttle is opened while the vehicle on which the carburetor is used is running at speeds below a speed of approximately 15-20 miles per hour on a level. At this speed, the throttle 98 begins to open and at all speeds higher than this, both throttles are open and both move simultaneously.

On opening of either or both throttles 66 and 98, the suction in the air chamber 96 is increased and the air valve 72 is opened against the tension of its spring to admit additional air and increase the quantity of mixture supplied to the engine. The opening of the valve must be temporarily retarded to some extent, however, to prevent admission of sufficient air to lean the mixture. For this the other end of which extends through the purpose and also to prevent fluttering of the valve, a dash pot is provided which comprises a cylinder 110, forming part of the casting 30,

and a piston 112 secured to the valve stem 84 in any desirable manner, asby means of a.

nut 114. A by-pass 116 is provided in the 'partiallgl reducing the resistance of the dash pot, as lly described, and forthe same purpose as in the above mentioned copending application.

In addition to the above described by-pass another passage 120 is provided in the casting 30, accordingto the present invention, to provide another means for escape of fuel from the dash pot which is effective under certain conditions to control the retarding effect of the dash poton said air valve. This passage is provided with an outlet port 122, communicating with the float chamber and the flow through said passage is controlled by a valve 124, received in a bore 126, in the casting 30, and cooperating with a vertical portion of the passage 120. This valve is secured to-a rod 128, connected at its upper end to an car 130, projecting from a diaphragm 132, operated by manifold suction, as hereinafter described, the valve being normally heldclosed by two springs, one of which is numbered 134 and surrounds the rod 128, being received between the upper end of the valve and a disk 136 lying between the spring and a projecting. portion of the casting 30, as

shown in Fig. 2.

The diaphragm 132 forms the bottom wall of a chamber 138 formed within an inverted cup shaped member 140, which may be secured to the main casting 20 in any suitable way, as by means of an arm projecting therefrom which may be secured by screws to the casting. Extending into the chamber 138 through the member 140 is a suction pipe 142,

wall of the casting 20 into the main air passage 96 at a-point anterior to the throttle 98 so as to be at all times subject to the manifold vacuum. Any suitable means for preventing leakage around the ends of the pipe 142 where it passesthrough the member 140 and the casting 20 may be employed. The diaphragm 132 is flexible and is normally held in its lower position, as shown in Fig. 2, by a spring 144, received within the chamber 138,

and aiding the spring 134 to hold the valve 124 upon its seat.

At idling, and at'all speeds when the motor is operating under a load, the suction commue nicated to the chamber 138 is insuificient to overcome the force of springs 134 and 144, and the valve 124 is held closed preventing escape of fuel through the passage 120, sov that the resistance of the dash pot is never re lieved except by the by-pass 116, when the motor is operating under load. Therefore, on any opening of the throttle, except under the specific operating conditions hereinafter described, the valve 124 will be in position to close the passage 120 and the dash pot will operate to retard to some extent the opening of the-air valve, and thus tend to enrich the mixture by restricting the admission of air temporarily.

Under certain operating conditions, how: ever, it is not desirable that openin movements of the throttlebe accompanie by any enrichment of the mixture, and the present invention constitutes means to permit substantially. unrestricted opening of the air valve at such a time. For instance, when an automobile on which the device disclosed herein is used is coasting down hill at rela- 1 tively high speed with the clutch engaged and the throttle opened, at the end of the, coast there is no need to enrich the mixturebecause the engine is already running at speed. During coasting, as above described, the manifold suction which is communicated to the diaphragm 132 through the pipe 142 is sufl'icient to open the valve 124 against the pressure exerted by springs 134 and 144. Therefore, when the throttle is opened at the end of the coast, the air valve may open substantially without retardation. As the valve opens, how-ever, the suction effective on the diaphragm 132 is rapidly reduced so that the valve 124 is closed by springs 134 and 144 when the opening movement of theair valve is completed, and on any subsequent opening movement of the throttle, unless such move-- It will be clear from the foregoing that X when the manifold suction is very high, as when the engine is running at relatively high speed with the throttle closed, an opening movement of the-throttle is accompanied by an unretarded movement of the, air valve and no mixture enrichment, while on opening of the throttle under all other conditions, the dash pot retards the opening of the airvalve restricting theadmisslon 0 air and temporarily increasing'the proportion of fuel in i the mixture. I v I The primary mixture is conveyed through primary mixture conduits previously described to the secondary mixing chambers in each outlet branch of the main air mamfold, which are identical in construction and only one of which is shown herein. Each secondary mixing chamber comprises a Venturi tube 150 having a projecting rib .152 formed on its outer surface, the rib being clamped between shoulders 154 and 156 on the manifold 'andengineblockrespectively,

when the device is assembled. The primary mixture conduits terminate at the point of greatest suction Within the Venturi tubes so as to produce a high velocity within the said conduits.

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.

WVhat is claimed is as follows:

1. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, means for temporarily restricting the admission of air on opening movements of the throttle and suction operted means operative to render said restricting means ineffective under certain predetermined and abnormal operating conditions, said suction operated means being inoperative under all normal operating conditions.

2. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, means for enriching the mixture on opening movements of the throttle and means operated by manifold suction for rendering said mixture enriching means ineffective on opening of the throttle under certain predetermined and abnormal operating conditions, said suction operated means being inoperative under all normal operating conditions.

3. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing chamber, a dash pot for retarding the opening of the air valve on opening of the throttle and suction operated means for controlling the effectiveness of said dash pot ineffective under certain abnormal operating conditions, said last named means being inoperative under all normal operating conditions.

4. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixingchamber, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the effectiveness of the dash pot and suction operated means for controlling the flow through said passage.

5. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing chamber, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the effectiveness of the dash pot, a valve for controlling said passage, and suction operated means for operating said last-mentioned valve.

6. A charge forming device for internal combustion engines, comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing chamber, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the efi'ectiveness of the dash pot, a normally closed valve for controlling said passage and suction operated means for opening said lastmentioned valve under certain predetermined operating conditions.

7. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing chamber, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the effectiveness of the dash pot, a normally closed valve for controlling said passage and means operated by the suction between the throttle and the engine for opening said last mentioned valve under certain predetermined operating conditions.

8. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing chamber, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the effectiveness of the dash pot, a valve for controlling said passage and means operated by the suction posterior to the throttle for operating said last-mentioned valve.

9. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing chamher, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the effective ness of the dash pot, a valve for controlling said passage, a suction operated diaphragm connected to the valve and a suction connection communicating with the intake passage posterior to the throttle for communicating the manifold suction to the diaphragm.

10. A charge forming device for internal combustion engines comprising, a mixing chamber, means for supplying fuel and air thereto, a throttle, an air valve for controlling the admission of air to said mixing cham her, a dash pot for retarding the opening of the air valve on opening of the throttle, a passage for permitting escape of fluid from the dash pot cylinder to regulate the effectiveness of the dash pot, a valve for controlling said passage, means operated by the manifold suction for opening the valve and resilient means for holding the valve closed, the pressure-exerted by such means being such that the manifold suction is suflicient to overcome such pressure only when the engine is running at relatively high speed with the throttle closed.

11. A charge forming device forinternal combustion engines having in combination, a secondary mixing chamber, aprimary carburetor for supplying a primary mixture to the said secondary mixing chamber, means for supplying fuel and airthereto, a main air passage supplying-air. to said secondary mixing chamber, a valve regulating the admission of airto saidmain air passage, a throttle in said main air passage, a dash pot for normally retarding opening movements of said valve, and means operated by the suction in the main air passage posterior to the throttle therein for controlling the effectiveness of the dash pot.

12. A charge forming device for internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying a primary mixture of fuel and air to said secondary mixing chambers, means for supplying fuel and air thereto, a main air passage supplying air to all of said secondary mixing chambers, a primary throttle controlling all of said primary carburetors, a secondary throttle in said main air passage, a suction operated valve controlling admission of air to said main air passage, means for retarding the opening of said main air valve and means operated'by the suction in the main air passage posterior to the throttle for regulating the effective ness of said retarding means.

13. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a throttle regulating the flow of mixture therefrom, means for enriching the mixturevduring the acceleration period following opening movements of the throttle, means for variably controlling the effectiveness of the mixture enriching means for any opening movement of the throttle in accordance with different operating conditions prevailing when said movement of the throttle takes place, and another means operated by manifold suction for rendering'said enriching means ineffective on opening of the throttle under certain abnormal operating conditime, said suction operated means being inoperative under all normal operating conditions.

her, a dashpot for retarding the opening of the air valve on opening movements of the throttle in order to enrich the mixture during the acceleration period following any such movement of the throttle, means for varying the retarding effect of the dashpot according to the position of the air valve at the beginning of the throttle movement, and suction operated means for rendering the dashpot ineffective under certain abnormal operating conditions, said last named means being inoperative under all normal operating conditions. i

15. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a throttle controlling the flow of mixture therefrom, an air valve for controlling the admission of air to the mixing chamher, a dashpot for retarding the opening of the air valve following opening movements of the throttle, a passage controlled by the position of the air valve for permitting escape of fluid from the dashpot cylinder to control the retarding efiect thereof, a second passage for permitting escape of fluid from the dashpot to control its retarding effect, and suction operated means for controlling the flow of fluid through said second passage,

16. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a throttle controlling the flow of mixture therefrom, an air valve for controlling the admission of air to the mixing chamber, a dashpot for retarding the opening of the air valve following opening movements of the throttle comprising a piston connected ,to the air valve and a cooperating cylinder,

a plurality of passages for permitting escape of fluid from said dashpot to control the retarding efi'ect thereof, one of said passages being controlled by the dashpot piston, and suction operated means for controlling the flow of fluid through the other of said passages.

In testimony whereof I hereto atfix my signature.

FRED E. ASELTINE.

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