US2993684A - Accelerating pump - Google Patents

Description

July 25, W61 M. F. STERNER ACCELERATING PUMP 2 Sheets-Shea?, l

Filed NOV. 17, 1958 INVENTOR. MEA V//V {57am/,6P

July 25, 1961 M. F. STERNER 2,993,684

ACCELERATING PUMP Filed Nov, 17, 1958 2 Sheets-Sheet 2 i V22 INVENTOR.

/ MQ z//A//f/P/vf/Q un E? 5 A Tram/5y 2,993,684 ACCELERATING PUMP Melvin F. Sterner, Bloomfield Hills, Mich., assignor to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Nov. 17, 1958, Ser. No. 774,270 Claims. (Cl. 261-34) This invention relates generally to pumps, and more specifically to accelerating pumps used in carburetors for internal combustion engines.

When an engine is called upon to accelerate rapidly,

the air flow through the carburetor responds almost immediately to the increased throttle opening; however, the fuel, which is heavier than air, lags a substantial amount behind the increased air ow thereby causing a leaning out of the fuel-air ratio. The accelerating pump is designed to correct this condition by supplying liquid fuel until the other fuel metering systems once again are providing the proper mixture.

' The performance of accelerating pumps in general, has been seriously impaired by the fuel vapors trapped within the accelerating pump system. The presence of these vapors is attributed to those situations where an excessive amount of heat is created within the engine compartment, whether by a hot shut-down or prolonged idling of the engine. When vapor is trapped within the system, it displaces a volume therein which liquid fuel would normally occupy. Therefore, when the accelerating pump is called upon for additional fuel, none will be supplied because of the absence of liquid fuel.

Accordingly, it is an object of this invention to provide means for removing any vapor within the accelerating pump system.

More specifically, it is an object of this invention to provide automatic means for at times removing vapor from within the accelerating-pump system.

Other objects and advantages will become apparentr when reference is made to the following specification and illustrations wherein:

FIGURE 1 is a side elevational View, with portions thereof cut away and in cross-section, of a carburetor embodying the invention.

FIGURE 2 is a perspective view, with portions thereof cut away and in cross-section, of the carburetor shown by FIGURE l, but with the fuel bowl removed so as to illustrate the construction of the accelerating pump and associated linkage.

FIGURE 3 is an enlarged cross-sectional fragmentary view 'of the accelerating pump nozzle and system taken on a plane substantially through the center of the carburetor body and pump nozzle.

Referring now in greater detail to the drawings, FIG- URE l illustrates a carburetor having a body 12 with an induction passage 14 extending therethrough. The usual choke valve 16 controlling the entrance of the air intake 18 and throttle valve 20 controlling the How of combustible mixture to the engine intake manifold 22 are provided.

A main fuel system is defined by metering restriction 24, conduits 26 and 28 and nozzle 30 which discharges as required within the induction passage 14. An idle system having a minimum idle and a transfer portion is schematically comprised of restriction 32, conduits 34 and 36, and port 38 and slot 40 which discharge selectiveof a reinforced diaphragm 54 secured to the bottom of the fuel bowl by a member 56 and thereby creating a chamber 58. The chamber 58 communicates with chamber 44 of the fuel bowl 42 by means of passage 43 having a gravity actuated ball check valve 60. Chamber 58 also communicates with the pump nozzle assembly 62 by means of conduits 64, 66, 68 and 70.

A screw 72 and housing 74 cooperatively defining a chamber 76, constitute the basic nozzle assembly. Nozzle 78, which may either be formed as part of housing 74 or secured thereto, communicates with chamber 76 and is directed towards the induction passage v14. The screw 72 is threadably received by the body 12, and a passage 80 formed in screw 72 is provided as a means of communication between chamber 76 and conduit 70. A seat 82 is provided Within conduit 70, and a ball 84 and weight 86 are placed between the seat and chamber 76.

A separate conduit 88 formed in body 12 and housing 74 communicates between the atmosphere, through restriction 90, and a source of engine vacuum. A ball check valve 92 resiliently urged upwardly by spring 94 against seat 96 is located in such a manner so as to, at times, positively restrict any ow through conduit88. The force of spring 94 may be varied by providing a threaded spring abutment 99. A calibrated passage 102 is provided as a means of communication between chamber 76 and conduit 88. Other calibrated restrictions such as 104 may be provided in order to adapt the invention to a particular set of operating conditions.

Operation The general operation of the accelerating pump is briefly as follows: When the throttle 20 is manually opened in the usual manner, they pump linkages 52 and 98 force the pump diaphragm 54 upwards. As the diaphragm moves up the pressure forces the pump inlet ball check valve 60 closed thereby preventing fuel from owing back into the chamber 44. The fuel within chamber 58 ows from there through conduits 64, 66, 68 and to conduit 70; this causes the ball 84 and weight 86 to raise, thereby discharging the fuel from chamber 76 through nozzle 78 into the induction passage 14.

As the throttle 20 is moved toward the closed position, the linkages 52 and 98 return to their normal positions and the diaphragm 54 is forced downwardly by spring 100. As the diaphragm returns to its original position, the pump inlet ball check valve 60 is opened and chamber 58 is filled with fuel from the fuel b'owl.

The specific improvement which this invention proposes will be more readily appreciated if it is first assumed that the engine has been started after a period of hot shut-down and is idling.

During periods of engine idling, the manifold vacuum will be at a higher value than during those periods of off-idle operation. Therefore, during this assumed state, vacuum of sufficient magnitude will be directed to the ball check 92 causing it to move off seat 96 against the force of spring 94. Under this condition, the entire accelerating pump system will be exposed to and acted upon by manifold vacuum, thereby causing any vapors therein to be drawn into the induction passage.

As engine speed increases, manifold vacuum will decrease accordingly thereby allowing spring 94 to once more seat the ball check valve 92.

From the foregoing it becomes readily apparent that automatic purging of fuel vapors is accomplished during any particular selected engine speed range.

Although only one embodiment of the invention has been disclosed and described, it is apparent that other modifications of the invention are possible within the scope of the appended claims.

What I claim as my invention is:

1. In a carburetor for an internal combustion engine having an acceleration fuel system, means operative during certain periods of engine operation for removing vapors from Within said acceleration system, said means comprising a conduit pneumatically connecting a source of engine vacuum with said acceleration system and including vacuum responsive valve means disposed within said conduit for controlling flow therethrough.

2. In a carburetor for an internal combustion engine, said carburetor having an induction passage communicating with the intake manifold of said engine, the combination of a throttle valve controlling the flow of combustible mixture through said induction passage, an idle fuel system discharging into said induction passage posterior to said throttle valve, a main fuel system at times discharging into said induction passage anterior to said throttle valve, an acceleration fuel system adapted to discharge additional fuel into said induction passage anterior to said throttle, a conduit communicating between a source of vacuum and a vapor collecting portion ofsaid acceleration fuel system, means disposed within said conduit for preventing any flow therethrough whenever the vacuum at said source decreases below a predetermined minimum value, said means being comprised of a ball check valve resiliently urged in a closing direction against a coacting seat member.

3. A carburetor adapted to be mounted on the intake manifold of an internal combustion engine, comprising a body with an induction passage therethrough communieating with said intake manifold, a choke valve controlling the intake of said induction passage, a throttle valve in said induction passage for determining the amount of combustible mixture passing therefrom, an idle fuel system discharging into said induction passage posterior to said throttle valve, a main fuel system discharging at times into said induction passage anterior to said throttle valve, an acceleration fuel system operatively only during opening movement of said throttle valve for supplying additional quantities of liquid fuel to said induction passage, conduit means for communicating between a vapor collecting portion of said acceleration fuel system and a source of engine intake manifold vacuum, and valve means responsive to engine intake manifold vacuum for preventing any flow of vapors through said conduit means below a predetermined value of said intake manifold vacuum.

4. A carburetor adapted to be mounted on the intake manifold of an internal combustion engine, comprising a body with an induction passage therethrough communieating with said intake manifold, a choke valve controlling the intake of said induction passage, a throttle valve in said induction passage for determining the amount of combustible mixture passing therefrom, an acceleration fuel system operative only during opening movement of said throttle valve for supplying additional quantities of liquid fuel to said induction passage, conduit means for .communicating between a vapor collecting portion of said acceleration fuel system and a source of engine intake manifold vacuum, and valve means responsive to engine intake manifold vacuum for preventing any flow yof vapors through said conduit means below a predetermined value of said intake manifold vacuum.

5. In a carburetor for an internal combustion engine, said carburetor having an acceleration fuel system, means for drawing off fuel vapors from said acceleration fuel system during engine operation, and additional means responsive to engine vacuum for preventing said iirst mentioned means from drawing off said fuel vapors during those periods of engine operation wherein said engine vacuum is below a predetermined minimum value.

References Cited in the le of this patent UNITED STATES PATENTS 2,252,958 Bicknell Aug. 19, 1941 2,689,533 Ericson Sept. 21, 1954 2,741,465 Redman et al Apr. 10, 1956 2,775,436 Zub Dec. 25, 1956 2,879,048 Smitley Mar. 24, 1959

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