US1916906A - Charge forming device - Google Patents

Description

July 4-, 19330 F. E. ASELTINE CHARGE FORMING DEVICE Filed June 29, 1929 Patented July 4, 1933 UNITED STATES PATENT @FFEQE FRED E. ASELTINE, OF DAYTON, OHIO, ASSIGNOE TO DELCO PRODUCTS CORPORATION, OF DAYTCEII, (EH1 l1 CORPGBATION 01? DELAWARE CHARGE FORIKING DEVICE Application filed June 29,

1 495 issued Aug. 18, 1981.

It is the principal object of the present invention to secure in a device of this character the greatest possible economy in fuel consumption without loss of power or engine efficiency. More particularly it is the object of this invention to provide means in a device of this character to supply a relatively lean mixture during operation throughout the normal driving range and a richer mixture under other operating conditions.

Briefly, this object is accomplished by the provision of an air inlet which is closed when the throttle is in relatively closed or relative- 1y wide open positions but is opened when the throttle is in intermediate positions.

Further objects and advantages of the present invention 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 vertical, longitudinal section through a charge forming device constructed in accordance with the present invention, and the intake port with which it is associated.

Fig. 2 is a fragmentary, transverse, vertical section on the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary side elevation of the main carburetor unit.

Fig. 4 is a view similar to 3.

Fig. 5 is a. fragmentary section on the line 5-5 of Fig. 4.

The device disclosed C(Jll'l'PliSGS a main air manifold 10, having three outlet branches, the middle branch 12 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 mani- IQZS. Serial Ila. 374,869.

fold to the engine block in the usual manner, and a flange 18 to which the carburetor unit is secured.

The carburetor unit comprises a main housing 20, having an attaching flange 22, adapted to be secured to the flange 18 by screws 2-1. An air inlet coupling 28 is secured in position to register with an opening in the upper wall of the housing 20, in any suitable (3 way and may be connected with an air cleaner 4) if oesired. A casting 30, in which the passages supplying fuel to the nozzles are formed, is secured by screws to the lower wall of housing 20, and a sheet metal fuel bowl 32 is held 2 tight against an annular shoulder 3 1 on the 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 substantial 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 chambers t0, the construction of which is briefly described hereinafter. The fuel conduit be tween the fuel bowl and the nozzles comprises 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 i6. Euel is ad mitted 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 i-auction which might permit the fuel column to drop sufiiciently to cause a temporary fuel starving of the engine unless means are provided to prevent this action. For this purpose a check valve 5 1 is provided in an en larged chamber 56 at the junction of the channels 12 and 4%, and on reduction of mixing chamber suction, seats on the bottom of 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 out-let 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 chambers comprise the enlarged anterior ends of the primary mixture passages 64, which are parallel to each other and close together. as indicated in Fig. 2. lVhen 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 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 fuel nozzles for a purpose fully set fort-h in the above 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 mixture passages. Thisthrottle is operated by means hereinafter more fully described. The middle primary mixture passage communicates with a tube 72 fixed in the manifold 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 flows 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 011 a stationary guide sle ve 84, fixed in the housing 20, and serving also as aguide for the stem 86 to which the air valve is secured. hen 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, until the upper end of the sleeve 82 engages the air valve to hold it closed. Sullicient air to carry the starting fuel from the nozzles to the intake ports is admitted through an elongated slot 90, formed in a plate 92, secured to the housing 20, as shown in Fig. 1.

The valve 74: admits air to the air chamber 94tfrom which air flows to the primary mixture passage, through an orifice 96 in the bottom of the air chamber and to the secondary mixing chambers through av passage 08, which connects with the inlet of the manifold 10. A manually operable throttle 100 secured to a shaft 102, rotatably mounted in the housing and operated by means hereinafter fully described, controls the flow of air through the passage 98.

The operating connections for the throttle valves are fully described in the above mentioned application and it is sutlicient for the purposes of the present disclosure to state that the primary throttle is operated by means of an arm 10l secured in any desirable manner to a spindle 106 projecting from one end of the throttle and adapted to be connected at its free end to some form of connection extending'to a point convenient to the operator of the vehicle. The operating arm is connected by means of a lost motion connection, indicated in its entirety by the reference number 108 to an arm 110 secured to one end of the shaft 102. This construction permits a limited movement of the primary throttle independent of the air throttle 100 enabling the primary throttle to be partially opened while the air throttle remains completely closed. The lost motion 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 air throttle begins to open and at all higher speeds the two throttles move simultaneously.

On opening of one or both of the throttles 68 and 100, the suction in the air chamber is increased and the air valve 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 air valve must be retarded to some extent, however, to prevent admission of sufficient air to lean the mixture. To accomplish this result and to prevent fluttering of the air valve a dashpot is provided comprising a cylinder 112 formed in the casting 30 and a piston 11% seoured tothe valve stem 86 by means of the flanged coupling 116 pinned to the stem and cooperating nut 118, as shown in Fig. 1 or in any other desirable manner. The dashpot may receive liquid fuel from the fuel reservoir through the medium of a check valve, (not shown) in the bottom of the dashpot. The dashpot is of conventional form and its specific construction constitutes no part of the present invention.

In order to accomplish the purpose of the present invention means are provided to supply air in addition to that supplied by the main air valve when the throttle is in intermediate positions, but which becomes ineffective when the throttle is nearly closed or open. To this end a boss 120 projecting from the main housin 20 is provided with a flat surface 122 as indicated in Figs. 3, 4 and 5. A small air passage 12 1 is bored through the wall of the housing and terminates at the surface 122. In substantially closed or open positions of the throttle tl'iis passage is closed by an arm 126 pivotally mounted on a pivot pin 128 screwed into the housing as shown in Fig. 5 and held against the flat surface 122 by a spring 130 surrounding the pin 128 between the arm 126 and the enlarged head of the pin 128.

The arm is provided intermediate its ends with an orifice 131 which is adapted to be moved into registry with the passage 12% as the primary throttle is moved toward open position, and after apredetermined movement of sai d throttle is adapted to be moved out of registry with the orifice 1241 on continued opening movement of said throttle. In order that the arm 126 may be moved in the manner described a roller 136 is rotatably mounted on the free end of said arm and engages a cam 138 adjustably secured by means of a set screw 140 or in any other desirable m; nner to the spindle 106 between the arm 10st and the housing. The cam is so shaped that during the first part of the opening movement of the throttle the roller 136 is moves upwardly until the orifice 13% fully registers with passage 124 at which time the high point of the cam is in engagementwith the roller. Fu 't-her opening of the throttle carries the cam 138 beyond the roller permitting the .atter to move downwardly until the arm 126 again reaches normal position and the passage 124 becomes fully closed when the throttle is in nearly wide open position. It will be noted that the spring 130 is connected at its opposite ends to the screw 128 and a pin 142 projecting from the arm 126 so as to hole tie roller 136 in engagement with the cam 138.

T he air which is admitted through ta passage 124 as above described is smlicien to fom a mixture. iaving the proportions which are most satisfactory for operation throughout the normal driving range, that is a mixture containing substantially ii'teen parts of air to one part of fuel by weight. lVhen the passage 12st is closed the reduction in the air supply results in the formation of a mixture which approaches thirteen parts of air to one of fuel which has been found to give better results at closed and open throttle positions. It will be understood that the cam 138 may be of any desired form and may be so shaped that the opening of the passage 124 will be effective before the open ing of the air throttle 100 or may be designed to open said passage 124 only after the throttle 100 opens The secondary mixing chambers comprise Ventnri tubes 150 r-rhich are positioned in the outlet l r: nches of the manifold adjacent the outlet ends of the primary miizture conduits. These Veni'ur "h an external rio 152 adapted ed ietw-een shoulders 1541 and 156 l and the engine block rcspecari times accelerate the deli very ends of the pri duits, increasing the veemrough fully set forth Poned applicati n.

of embodiment of the tion as herein disclosed, consti .rcferred form. it is to be underother forms might be adopted, all the scope of the claims which the secondary air pastively. flow of air past form itlan l is as f form n V p i cznnpiising a secondary mixing chambers, a

re passages deli oring e of fuel and air t'ie:eto, a 7mg fuel to SiliCl primary es, a primary throttle valve ollows:

novice tor internal ilurality plurality l 1. A (.lll'. combustion of of primary mi primary init-rt fuel inlet an;

regula flow throng-hall of said pasan air chamber for supplying air to all of sai r and secondary mixing Cllltil'lllk'." ed

with a main air inlet, means 7 mg t e mixture proporto said air )1! an. inlet adinittmg air chamber, and means operated by the prin'iary throttle for regulating the flow of air through said inlet.

2. it cha forming devicefor internal cmnlmstion engines tom; rising a primary mix ire pa :s a rel inlet therefor. a ondaiy mixing chamber into which the primary mixture p sage is a lapted to deliver a primary mix fuel and air, 1. secondary air passage for supplying air to said secondary mixing chan'ibcr, a. main air chann her for supplying to said secondar Y air passage and salt. primary mixture passage,

SQU-

erefor, a. primary throttle it h said primary El 1112i uniliary air inlet H1 cl amber when ly opened.

3. 1; ch -j; "vice for internal combustio asing a primary herefor, a secmii-zture 'l which the pridelive; a

prim: ry mi) re of net ant. air, a. secondary air passage for supplying air to said secmixture passage, an auxiliary air inlet admitting air to the main air chamber, a valve therefor, and means operated by the throttle when partly open to open said valve.

4. A charge forming device for internal combustion engines romprising a primary mixture passage, a fuel inlet therefor, a secondary mixing chamber into which the primary mixture passage is adapted to deliver a primary mixture of fuel and air, a secondary air passage for supplying air to said secondary mixing chamber, a main air chamher for supplying air to said secondary air passage and said primary mixture passage, a main air inlet therefor, a primary throttle controlling the flow through said primary mi ture passage, an auxiliary air inlet admitting air to the main air chamber, a normally closed valve therefor, and means operated by the throttle to open said valve when the throttle is moved to partly open position.

5. A charge forming device for internal combustion engines comprising a primary mixturepassage, a. fuel inlet therefor, a secondary mixing chamber into which the primary mixture passage is adapted to deliver a primary mixture of fuel and air, a secondary air passage for supplying air to said secondary mixing chamber, a main air chamber for supplying air to said secondary air passage and said primary mixture passage, a main air inlet therefor, a primary throttle controlling the flow through said primary mixture passage, an auxiliary air inlet admitting air to the main air chamber, a normally closed valve therefor and means operated by the throttle after a. predetermined opening movement to open said valve.

6. A charge forming device for internal combustion engines comprising a primary mixture passage, a fuel inlet therefor, a secondary mixing chamber into which the primary mixture passage is adapted to deliver a primary mixture of fuel and air, a secondary air passage for supplying air to said secondary mixing chamber, a main air chamber for supplying air to said secondary air passage and said primary mixture passage, a main air inlet therefor, a primary throttle controlling the flow through said primary mixture passage, an auxiliary air inlet admitting air to the main air chamber, a normally closed valve therefor and means operated by the throttle after a predetermined opening movement to open said valve, said means being so constructed as to cause movement of the valve to closed position upon further movement of the throttle toward open position.

7. A charge forming device for internal combustion engines comprising a primary mixture passage, a fuel inlet therefor, a sec ondary mixing chamber into which the primary mixture passage is adapted to deliver a primary mixture of fuel and air, a secondary air passage for supplying air to said secondary mixing chamber, a main air chamber for supplying air to said secondary air passage and said primary mixture passage, a main air inlet therefor, a primary throttle controlling the flow through said primary mixture passage, an auxiliary air inlet admitting air to the main air chamber, a valve controlling said auxiliary air inlet, and means for operating said valve comprising a cam operated by the primary throttle, said cam being so shaped to open and subsequently close said valve during a continuous opening movement of the throttle.

8. A charge forming device for internal combustion engines comprising a primary mixture passage, a fuel inlet therefor, a secondary mixing chamber into which the primary mixture passage is adapted to deliver a primary mixture of fuel and air, a secondary air passage for supplying air to said secondary mixing chamber, a main air chamber for supplying air to said secondary air passage and said primary mixture passage, a main air inlet therefor, a primary throttle controlling he flow through said primary mixture passage, an auxiliary air inlet admitting air to the main air chamber, a Valve for controlling the flow through said auxiliary air inlet comprising a pivoted arm and a cam operated by the primary throttle and engaging said arm whereby the arm is moved into position to open the inlet during opening movement of the throttle.

9. A charge forming device for internal combustion engines comprising a primary mixture passage, a fuel. inlet therefor, a secondary mixing chamber into which the primary mixture passage is adapted to deliver a primary mixture of fuel and air, a secondary air passage for supplying air to said secondary mixing chamber, a main air chamber for supplying air to said secondary air passage and said primary mixture passage, a main air inlet therefor, a primary throttle controlling the flow through said primary mixture passage, an auxiliary air inlet admitting air to the main air chamber, avalve for controlling the flow through said auxiliary air inlet comprising a pivoted arm and a cam operated by the primary throttle and adapted to operate the arm, said cam being so designed that the arm is moved into position to even the air inlet during a part of the opening movement of the throttle, and is moved into position to close the passage during another part of said opening movement.

In testimony whereof 1 hereto affix my signature.

FRED E. A SELTINE.

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