US2989292A - Accelerating pump - Google Patents

Description

June 20, 1961 F. J. MARSEE 2,989,292

ACCELERATING PUMP Filed Sept. 18, 1958 3 Sheets-Sheet 1 I NVEN TOR. flefQ/c/JMA/Psff libwww/)5,

June 20, 1961 F. J. MARsr-:E

ACCELERATING PUMP 5 Sheets-Sheet 2 Filed sept. 18, 1958 I NV EN TOR. kEf/P/c/(JMAPSEE June 20, 1961 F. J. MARSEE 2,989,292

ACCELERATING PUMP Filed Sept. 18, 1958 5 Sheets-Sheet 3 C1 /7/\\ C s IN VEN TOR.

out ofthe fuel air-ratio. vsigned -to correct this condition by supplying hquid fuel f pump system while at the Sametime preventing 2,989,292v ACCELERATING PUMP Frederick J. Marsee, Royal Oak, Mich., asslgnor to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Sept. 18, 1958, Ser. No. 761,706 y 6 Claims. (Cl..26134) z invention relates generally to pumps, and vmore specifically to accelerating pumpsused incarburetors for internal combustion engines.

When an engine is called upon to accelerate rapidly, the air ow through the carburetor responds almost imlmediately to the increased throttle opening; however, the

fuel, 'which is havier than air, lags a substantial amount behind the increasedv air flow thereby causing la'leamng- The accelerating pump is deuntil 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 lpresence of these y vapors is attributed to those situations where anexcelssive amount of :heatis created within the engine compartment, vwhether 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 nor- `.m'ally occupy. Therefore, when the 'accelerating pump is called upon for additional fuel, none willbe supplied `because of the absence of liquid fuel.

' Means have been devised whereby engine vacuum is 'Y applied to the accelerating pump system in order to draw desirable vacuum Vbleed-off.

come more apparent when reference is made to the following specifcation 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 of the carburetor shown by IFIGURE 1 with portions thereof cut away and in cross-section and having the fuel bowl removed, with the exception of the accelerating pump and associated linkage.

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

FIGURE 4 is a graph illustrating generally manifold vacuum values for engines equipped with acceleration systems of present and proposed designs.

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 carburetor is provided with the usual choke valve 16 controlling the entrance of the air intake 18 and throttle valve 20 controlling the tflow of combustible mixture to the engine intake manifold 22.

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 selec- United States. F

Other objects and advantages of the invention-willy be- ICC . 2 v; tively below the throttle valve 20. A fuel bowl 42, dening a chamber 44 and having yan inlet 46, is secured as by screws 48 to the body 12 in a manner to supply all of the fuel systems with a source of fuel. An accelerating pump 50 is attached to the bottom of the fuel bowl and is adapted to be actuated by levers 52 and 98.

FIGURE 2 illustrates the pump '50 as being comprised of a reinforced diaphragm 54 secu-red to the bottom of the fuel bowl by amember 56, thereby creating a chamber 58. The chamber 58 communicates with chamber 44 of the fuel bowl 42r by means of a passage 59 having a gravity actuated ball check valve 60 and conduit 43. 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 7,8, which may either be formed as part of housing 74 or securedthereto, communicates with chamber 76 and is directed towards theI induction passage 14. Screw 72 is threadably received by the body 12, and a conduit 80 is formed therein. A second chamber 82, which is defined by a resilient seal 84, screw 72 and housing 14, communicates with conduits 80 and 72 by means of passages 86 formed radially within screw 72. Conduit 88, which is also formed within screw 72, serves to hydraulically connect chamber 76 with conduit 80.

A gravity actuated ball check valve 90, which may have an added weight 92 aiding it, cooperates with a seat 94 to at times prevent any flow as between passages 86 and conduit 88.

A separate conduit 96 formed in body 12 and housing `I74`communicates between the atmosphere, through restriction 102 and a source of engine vacuum. A second calibrated passage 104 connects conduit 96 with chamber 82. It is of course apparent that the relative orifice sizes of the various restrictions and conduits is a matter of adaptation to the particular engine and carburetor.

Operation The generalV operation of the accelerating pump is briefly as follows: When the throttle 20 is opened, the

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 flowing back into the chamber 44. The fuel Within chamber 58 ows from there through conduits 64, 66, 68 and to conduit 70 where it enters conduit 80 causing the ball 90 and weight 92 to raise; the fuel is subsequently discharged 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 the chamber 58 is filled with fuel from the fuel bowl.

The improvement contemplated by this invention will be more readily appreciated if it is first assumed that the engine has been started after a period of hot shutdown and is idling. At this time, Vacuum will be transmitted through conduit 96 and passage 104 into chamber 82. The vacuum will then draw off all fuel vapors from conduit 72 by means of conduit 80 and passages 86. However, it will be noted that due to the seal 84 and ball check valve no vacuum is applied to chamber 76; therefore, no back-bleeding effect will occur through the nozzle 78, regardless of the orifice size therein.

Reference to the graphs of FIGURE 4 will illustrate the importance of this feature. In FIGURE 4, graph A illustrates generally the manifold vacuum of an engine equipped with a non-purged acceleration system; graph B illustrates the manifold vacuum, relative to the condi- 3 tion of graph A, of an engine equipped with a purged acceleration system according to the present invention, while graph C illustrates the manifold vacuum relative to the conditions of both graphs A and B of an engine equipped with purged acceleration systems of present design.

It will be noted that the various curves of FIGURE 4 illustrate generally that all engines would operate satisfactorily and not exhibit any erratic action during periods of operation in which the acceleration system was not used. In contrast to this, if an engine equipped according to graph C were accelerated rapidly, the accelerating pump 50 would deliver raw fuel to the nozzle 78 thereby stopping the back bleed therethrough to conduit 96. When this happened, the manifold vacuum would raise to some value which would be equal to or approach curve B (this is illustrated by C1). Since fuel metering in almost all carburetors is controlled in accordance with manifold vacuum (except for main nozzle operation), these carburetors would deliver an over-rich mixture because of the false manifold vacuum value derived during the acceleration. The present invention eliminates this undesirable characteristic by preventing back-bleeding through the nozzle 78 for all driving conditions.

It will be observed that passages 86 may be of a size which will establish a critical iiow at manifold vacuums existing either at idle or at any other engine speed. Therefore, it would be possible to use this constant fixed ow as part of the idle fuel requirements of the engine.

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

What I claim is:

l. In a carburetor for an internal combustion engine having an acceleration fuel system and a nozzle assembly associated therewith with means for removing vapors from within said acceleration system, said nozzle assembly being comprised of an outer housing and an inner member which cooperatively form a chamber therebetween, said inner member having a main conduit therein communicating with a source of accelerating fuel, means disposed between said outer housing and inner member forming a dividing wall within said chamber and forming upper and lower chambers therein, radially formed passageways within said inner member adapted to communicate .between said main conduit and said lower portion of said chamber, a second main conduit formed within said inner member and adapted to communicate between said first main conduit and said upper portion of said chamber, a nozzle formed within said housing and communicating with Asaid upper portion of said chamber, and means disposed within said first main conduit forming a unidirectional check valve.

2. The structure as defined in claim l wherein said vapor removing means communicate with the lower portion of said chamber.

3. The structure as defined in claim 1 wherein said check valve is comprised of a gravity actuated ball 'and cooperating seat member.

4. In a carburetor for an internal combustion 'engine having an acceleration fuel system and a nozzle assembly associated therewith having means for removing vapors lfrom within 'said acceleration system, said nozzle 'assem bly being comprised of an outer housing and an inner member which cooperatively form a general chamber therebetween, means disposed between said outer housing and inner member forming a dividing wall within 'said general chamber and forming upper and lower chambers therein, rst passage means communicating between said upper chamber and a source of accelerating fuel, a nozzle portion communicating with said upper chamber, second passage means communicating between said rst passage means and said lower chamber, and means disposed within said first passage means forming a unidirectional check valve so as to prevent ow from said upper chamber to said lower chamber.

5. The structure as defined in claim 4 wherein said vapor removing means communicate with the lower portion of said chamber.

6. The structure as defined in claim 4 wherein said check valve is comprised of a gravity actuated ball and cooperating seat member.

References Cited in the file of this patent

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