US1946608A - Charge forming device - Google Patents

Description

Feb. 13, 1934. F. E. ASELTINE CHARGE FORMING DEVICE Filed May 23, 1930 2 Sheets-Sheet l Feb. 13, 1934. F. E. ASELTINE 1,946,603

CHARGE FORMING DEVICE Filed May 23, 1930 2 Sheets-Sheet 2 a 35 /zo l/ #8 Z 74 78 80 3 3e /5a 72' 4 mm .24

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a 3mm die/lbw c9? 3 J ns 5L4 l atented Feb. 13, 1934 PATENT OFFICE CHARGE FORMING DEVICE Fred E. Aseltine, Dayton, Ohio, assignor to Delco Products Corporation, Dayton, ()hio, a corporation of Delaware Application May 23, 1930. Serial No. 454,912

18 Claims.

This invention relates to charge forming devices for internal combustion engines, and more particularly to devices of this character which comprise a plurality of primary carburetors, each of which delivers a primary mixture of air and fuel to one of a plurality of secondary mixing chambers located adjacent the engine intake ports and in which the primary mixture is mixed with additional air under certain operating conditions.

Devices of this character are disclosed in the copending applications of Wilford I-l. Teeter and Fred E. Aseltine, Serial No. 221,371, filed September 22, 1927, and Wilford H. Teeter, Serial No. 221,372, filed September 22, 1927.

It is the object of the present invention to provide in a device of this character means for improving the proportions of the mixture during operation under all operating conditions, and particularly for enriching the mixture during the acceleration period and for delivering the enriched mixture to the cylinders substantially simultaneously with the opening of the throttle. With this object in view, one feature of the invention consists in the provision-of primary mixture passages which are supplied with air directly from the atmosphere instead of from the main air chamber, as in the earlier devices.

A further feature of the invention consists in the provision of a positively controlled needle valve for regulating the supply of fuel to the fuel jets during all operating conditions.

A still further feature of the invention consists in the provision of a cam for operating the above mentioned fuel valve which is adjustable on the throttle shaft so that by adjustment of such cam, the position of the fuel valve at idling can be readily accomplished.

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. 1 is a plan view of a charge forming device constructed in accordance with the present invention.

Fig. 5 is a fragmentary, left side elevation of the device with parts broken away and other parts shown in section.

Fig. 6 is a right side elevation of the device showing the throttle operating mechanism.

The device disclosed comprises a main air manifold 10 having three outlet branches 12, 13 and 14. Each of these branches communicates with one of the intake ports 15 of a multicylinder engine and each is provided with an attaching U6 flange 16 for securing it to the engine block in the usual manner. Adjacent its inlet, the manifold is provided with a flange 18 to which the carburetor unit is adapted to be secured.

The carburetor unit comprises a main housing 20, having an attaching flange 22, adapted to be secured to the flange 18 by screws 24. An air inlet coupling 26 is positioned in an opening in the upper wall of the main housing and admits air thereto, while a casting 28 which is provided for a purpose hereinafter described, is secured to the bottom of the main housing 20. A sheet metal fuel bowl 30 is held tight against a shoulder 32 formed on the casting 28 and fuel, which is conducted to a bowl from a main source of supply, is controlled by a float 34, which operates in the usual manner to maintain a substantially constant level of fuel in the bowl.

A plurality of primary mixture passages 36 are provided in'the lower wall of the main housing, the construction of these passages being more fully described hereinafter. Fuel is supplied to each of these passages by a plurality of fuel jets 38 and 40, the jet 38 functioning under all operating conditions and the jet 40 operating only at to relatively high speeds for reasons which will be more fully set forth later. Fuel is conducted to all of the fuel jets through a vertical passage 42, depending from a distributor block 44, secured by screws or in any other desirable way to the bottom of the main housing. The passage 42, at its lower end, communicates with a horizontal passage 46, which communicates in turn with a vertical passage 48 extending upwardly from the passage 42, all of the fuel passages being formed 16) in a single integral member. The fuel is admitted to the vertical passage 48 through an orifice 60 and the passage 48 is restricted at 62.,

a fuel valve 64 being received in the passage 48 and projecting into the restriction 62 to control the flow of fuel thereto. This valve extends upwardly through the top of the fuel bowl and is controlled by the primary throttle in a manner to be described more fully hereinafter. The vertical passage 42 connects at its upper end with horizontal fuel canal 66, which, through the orifices 68, supplies fuel to a channel 70, formed in the lower wall of the main housing and which communicates with all of the jets 38 and 40 in all of the primary mixture passages to supply fuel thereto.

According to the present invention, the mixture passages 36 are somewhat smaller than in the applications above referred to and instead of being supplied with air which is admitted through the coupling 26 in a manner hereinafter described,v

communicate directly with the atmosphere, each of said passages being provided with an air inlet bushing 72, which admits air thereto. Each of the primary mixture passages 36 is slightly enlarged at its anterior end, as indicated at 74 and a small Venturi tube '76 is positioned in each mixture passage within such enlargement, ribs 78 being formed on the Venturi tubes which fit relatively tightly within the enlargements 74 and when the Venturi tubes are in position they are held closely against shoulders 80 at the inner end of each enlargement 74 by means of the bushings '72, which are threaded in the wall of the housing and which may be screwed inwardly against one of the ribs 78 on each tube. The fuel jets 38, each supply fuel to an annular channel 82, formed in the wall of the main housing 20 and communicating with the space between the above mentioned shoulders 78, while each of the Venturi tubes is provided with a series of orifices 84, which connect the channels 82 with the interior of the Venturi tubes and supply fuel thereto from'the jets 38.

The inner ends of the Venturi tubes are reduced in size as indicated at 86, and these re- .duced ends are slightly spaced from the walls of the primary mixture passages to provide a space 88 between the wall of each mixture passage and the Venturi tube therein. The high speed fuel jets 40, each communicate with a short passage 90 in the wall of the housing, which in turn com- .municates with one of the spaces 88, above referred-to. Since the fuel feeding orifices 84. admit fuel to the interior of the Venturi tube at substantially the point of greatest suction therein, while the high speed fuel jets supply fuel to a space between the inner end of the Venturi tube and the well of the mixture passage which is protected from the aspirating action of the incoming air, it will be obvious that the high speed fuel jets are ineffective to supply fuel to the mixture passages until after a predetermined speed has been reached while the fuel inlets 84 will supply fuel to the Venturi tubes under all oper ating conditions. Means is provided for equalizing the'pressure in the three primary mixture pasages comprising a horizontal passage 85, bored in the wall of the main housing and three short vertical passages 87 extending downward from said horizontal passage, one of said passages 8'? connecting with each of the primary mixture passages 36. I

A single throttle valve 92 which extends across all of the mixture passages, is provided with grooves 94- which register with said passages and control the flow therethrough. This throttle is journalled in the housing 20 and is operated by means disclosed more fully herein. The primary mixture passages 36, when the device is assembled, are adapted to register withconduits which convey the primary mixture to secondary mixing chambers in the outlet branches of the manifold as fully disclosed-in copending application Serial No. 221,371. One of these conduits, which is in form of a tube 96, is fixed in the wall of the outlet branch 12 and conveys primary mixture to the secondary mixing chamber formed in that particular manifold branch, as shown in Fig. 1.

As stated above, the valve 64 which is received in the fuel passage 48, extends upwardly through the top of the fuel bowl, being held in its uppermost position by means of a spring 98 received between the upper end of the conduit 48 and a collar 100 secured to the valve stem. This valve is normally held in its lowermost position when the throttle is closed by means of a cam 102 adjustably secured on the end of a spindle 104 projecting from the primary throttle by means of a set screw 106 or other suitable means. The cam permits the spring 98 to lift the valve progressively as the throttle is moved toward open position to enlarge the fuel passage through the restriction 62, thus controlling the area of the fuel passage in accordance with the position of the primary throttle. It will be obvious that by adjustment of the cam on its spindle through the medium of the set screw, the position occupied by the valve when the throttle is in its closed or idling position can be varied to suit different requirements of the engine.

Air is admitted to the carburetor through the coupling 26 and is controlled by a valve 108 normally held against the seat 110 by a spring 112, secured between the valve and a flange 114 projecting from a sleeve 116, slidable on a sleeve 118, fixed in the main housing and guiding the stem 120 to the upper end of which the valve 108 is secured. In order to aid in starting the engine, the sleeve 116 is adapted to be lifted into engagement with the valve 108 by means not disclosed herein, to hold said valve closed. According to the present invention, air for carrying the starting fuel to the cylinders is supplied through the Venturi tubes hereinbefore described. The choke choke mechanism constitutes no part of the present invention and is fully disclosed in application Serial No. 221,371.

The valve 108 admits air to a main air chamber 122 which, according to the present invention, has no means of communication with the primary mixture passages as in the earlier forms of this device, but is adapted to supply air to the secondary mixing chambers through a secondary air passage 124, this passage being controlled by a manually operable throttle valve 126, secured to a shaft 128, journalled in the main. housing. The valve 126 is operated simultaneously with the primary throttle, the latter being provided with an operating arm 127, which is secured in any desirable manner to a spindle 129, projecting from one end of the throttle, and adapted to be connected to some form of operating-means extending to a point convenient to the operator of the vehicle. A link 131, which is pivotally connected with the arm 127 is also pivotally connected at its upper end withan arm 135, secured to one end of the shaft 128 in .any desirable way. It should be clear that there is no lost motion connection between the primary throttle and the valve 126, in this device as in the devices shown in the earlier applications above referred to. All movements of the throttle produce a corresponding movement of the valve 126. A hole 137 is provided in each valve to admit air during idling;

To prevent fluttering of the air valve and to retard its opening movement temporarily, following an opening movement of the throttle, to enrich the mixture during the acceleration period, a. dashpot is providedincluding a cylinder III 130 supported in a fixed sleeve 132, whichlis part of the casting 28. Slidable within the cylinder 130 is a piston 134, secured to the inner end of the valve stem 120 in the marmer disclosed in the above mentioned earlier applications. Port 136 is provided in the wall of the cylinder which '00- operates with a port 138 in the sleeve 132 to permit fuel to enter the cylinder. It will be obvious that on opening movement of the valve, the above mentioned cylinder and piston will retard its movement temporarily restricting the admission of air to the secondary mixing chambers and thus enriching the mixture temporarily to provide a mixture of the proper proportions to produce smooth acceleration.

The cylinder 130 isslidable within the sleeve 132 and is adapted to be lifted on opening movements of the throttle by a bifurcated arm 140, which has pins projecting therefrom and engaging in the groove 142 formed in the top of the cylinder. In order to simplify the disclosure, the operating means for this arm has not been shown herein since it is fully shown in the earlier applications. It is sufficient for the purposes of this disclosure to state that a shaft 144 to which this arm is secured, is adapted to be rocked on opening movements of the throttle so as to move the arm in a clockwise direction and lift the cylinder, thus increasing the retarding effect of the dashpot and aiding in the enriching of the mixture.

The secondary mixing chambers are in the form of Venturi tubes of identical construction, one of these tubes being indicated by the reference numeral 150 and shown in Fig. 2. Each of the Venturi tubes is provided with an external rib 152, which is adapted when the device is assembled, to be clamped between shoulders 154 and 156 on the manifold and engine block respectively. The tubes are so positioned that the point of greatest suction therein is approximately at the end of the primary fuel delivery conduits so as to accelerate the flow therethrough.

The operation of this device is substantially as follows. In the earlier applications above re ferred to, some difficulties have sometimes been observed on acceleration due to the fact that after the secondary air passage is opened, the air which is admitted following any opening movement of the throttle, beingmuch lighter than the rich primary mixture, reaches the secondary mixing chambers before the enriched primary mixture reaches such chambers. By means of the device disclosed herein, the velocity of flow of the primary mixture through *which is admitted to the primary mixture conduits is supplied directly from the atmosphere, the pressure differential is' much greater than in earlier designs and also much greater than between the ends of the secondary air passage. Therefore, the speed at which the primary mixture travels through such conduits is very greatly increased so that notwithstanding the greater. weight of the primary mixture and the effect of inertia due thereto, such primary mixture will reach the secondary mixing chambers substantially as soon as the air admitted through the main air inlet.

. Further, the supply of fuel to the primary mixture passages can'be more accurately controlled when the supply is regulated at all speeds by a valve controlled by a cam, the ,design of which can be varied to suit the conditions which are met in any particular engine than where the fuel is controlled in part by a fixed meteringorifice and during otheroperating conditions isalso controlled by a fuel valve which is brought into action'at some predetermined speed. In earlier charge forming devices of this general type a fuel valve was employed which was designed -to be opened approximately at the same time the auxiliary air passage was opened but unless the parts were accurately synchronized so that the opening of the fuel valve would begin at exactly the correct time, the mixture was inaccurate, and. it was found to be very difficult to keep the parts operating in exact synchronization, particularly in event of the parts becoming worn. In this device, however, the valve begins to open immediately .as the primary throt tle and the secondary throttle are opened and is opened continuously as they are opened so that the above difliculties are largely avoided.

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 having a plurality of intake ports, comprising a main air manifold having outlet branches communicating with said intake ports, a plurality of primary carburetors each of which is adapted to supply a superrich mixture to one of said branches under all operating conditions, throttling means controlling the flow from the primary carburetors and a single secondary throttle for controlling the flow through a plurality of the outlet branches of said manifold.

2. A charge forming device for internal combustion engines having a plurality of intake ports, comprising a -main air manifold having outlet branches communicating with said intake ports, a plurality of primary carburetors each of which is adapted to supply a super-rich mixture to one of said branches under all operat-' ing conditions, throttling means controlling the fiow from the primary carburetors and a single secondary throttle for controlling the flow through all of the outlet branches of said manifold.

3. A charge forming device for internal combustion engines having a plurality of intake ports, comprising a main air manifold having 185 outlet branches communicating with said intake ports, a plurality of primary carburetors each of which is adapted to supply a super-rich mixture .to one of said branches under all operating conditions, throttling means controlling the flow from the primary carburetors an air bustion engines having a plurality of intake each of which is adapted to supply a super-rich mixture to one of said branches under all operating conditions, throttling means controlling the flow from the primary carburetors a single secondary throttle for controlling the flow through the outlet branches of the manifold, and means for admitting air direct from atmosphere to the primary carburetors.

5. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality ,of primary carburetors for supplying a. superrich primary mixture of air and fuel to said secondary mixing chambers under all operating conditions, an air passage supplying air to all of said secondary mixing chambers, a single primary throttle controlling said primary carburetors, a single secondary throttle regulating flow through said air passage, and means for operating the two throttles simultaneously.

6. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying a primary mixture of, air and fuel to said secondary mixing chambers under all operating conditions, a single primary throttle controlling said primary carburetors, a single secondary throttle regulating flow through said secondary mixing chambers, and means for operating the two throttles simultaneously throughout the entire movement of said throttle.

'7. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying a super-rich primary mixture of air and fuel to said secondary mixing chambers under all operating conditions, a single primary throttle controlling said primary carburetors, a single secondary throttle regulating flow through said secondary mixing chambers, and means for operating the two throttles simultaneously throughout the entire movement of said throttles.

8. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying a superrich primary mixture of air and fuel to said secondary mixing chambers under all operating conditions, an air passage supplying air to all of said secondary mixing chambers, a single primary throttle controlling said primary carburetors, a single secondary throttle regulating flow through said air passage, and a common operating means for the two throttles.

9. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying a superrich primary mixture of air and fuel to said secondary mixing chambers under all operating conditions, a single primary throttle controlling said primary carburetors, and a single secondary throttle for regulating the flow through the secondary mixing chambers, and common operating means for the two throttles.

10. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors adapted to supply a super-rich mixture of fuel and air to said secondary mixing chambers, a primary throttle controlling fiow through said primary carburetors, a secondary throttle controlling the fiow of air to said secondary mixing chambers, and means I associated with secondary throttle to permit the flow of a limited amount of air to said secondary mixing chambers during the idling of the engine.

11. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors adapted to supply a superrichmixture of fuel and air to said secondary mixing chambers, a primary throttle controlling flow through said primary carburetors, a secondary throttle controlling the flow of air to said secondary mixing chambers, and provided with an orifice therein to admit a limited amount of air during the idling of the engine.

12. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors adapted to supply a super-rich mixture of fuel and air to said secondary mixing chambers, a primary throttle controlling the flow through the primary carburetors and adapted to be held in a slightly open position during the idling of the engine, a secondary throttle controlling the fiow of air to the secondary mixing chambers, means holding said throttle closed at idling, said secondary throttle having an orifice therein to admit a limited amount of air to the secondary mixing chambers when said throttle is closed.

13. A charge forming device for internal combustion engines having a plurality of intake ports comprising a plurality of secondary mixing chambers supplying fuel mixture to said ports, a plurality of primary carburetors supplying fuel mixture to said secondary mixing chambers, primary and secondary throttles controlling the primary carburetors and secondary mixing chambers respectively, a fuel conduit having a single fuel metering orifice for supplying all the fuel to said primary carburetors and means operated by one of said throttles for regulating the flow of fuel through said-orifice. "14. A charge forming device for internal combustion engines having a plurality of intake ports .comprising a plurality of secondary mixing chambers supplying fuel mixture to said ports, a plurality of primary carburetors supplying .fuel mixture to said secondary mixing chambers, primary and secondary throttles controlling the primary carburetors and secondary mixing chambers respectively, a fuel conduit having a single fuel metering orifice forsupplying all the fuel to said primary carburetors, and means operated by the primary throttle for regulating the flow of fuel through said orifice.

' '15. A charge forming device for internal combustion engines having a plurality of intake ports comprising a plurality of secondary mixing chambers supplying fuel mixture to said ports, a plurality of primary carburetors supplying fuel mixture to said secondary mixing chambers, primary and secondary throttles controlling the primary carburetors and secondary mixing chambers respectively, a fuel conduit having a fuel metering orifice for admitting fuel to said primary carburetors, and means operated by one of said throttles for variably regulating the flow of fuel through said orifice during the entire movement'of said throttle.

16. A charge forming device for internal combustion engines having a plurality of intake ports comprising a plurality of secondary mixing chambers supplying fuel mixture to said ports, a plurality of primary carburetors supplying fuel mixture to said secondary mixing chambers, primary and secondary throttles controlling the primary carburetors and secondary mixing chambers respectively, a fuel conduit having a fuel metering orifice for admitting fuel to said primary carburetors, and means operated by said primary throttle for variably regulating the flow of fuel through said orifice during the entire movement of said throttle.

17. A charge forming device for internal combustion engines having a plurality of intake ports comprising a plurality of secondary mixing chambers supplying fuel mixture to said ports, a plurality of primary carburetors supplying fuel mixture to said secondary mixing chambers, primary and secondary throttles controlling the primary carburetors and secondary mixing chambers respectively, means for supplying fuel to said primary carburetors and means operated by the primary throttle for determining the entire amount of fuel supplied to the primary carburetors during all operating conditions.

18. A charge forming device for internal combustion engines having a plurality of intake ports comprising a plurality of secondary mixing chambers supplying fuel mixture to said ports, a plurality of primary carburetors supplying fuel mixture to said secondary mixing chambers, primary and secondary throttles controlling the primary carburetors and secondary mixing chambers respectively, a fuel feeding orifice for supplying fuel to said primary carburetors, a fuel valve controlling the flow of fuel therethrough and a cam operated by the primary throttle throughout its movement for varying the supply of fuel in accordance with the movement of the throttle.

FRED E. ASELTINE.

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