US2656851A - Fuel pump delivery valve - Google Patents

Description

Oct. 27, 1953 w, mc o s 2,656,851

FUEL PUMP DELIVERY VALVE Filed Sept. 7, 1950 INVENTOR W/LL/AM M. MIC/401.5

ATTORNEY Patented Oct. 27, 1953 FUEL PUMP DELIVERY VALVE William M. Nichols, Schenectady, N. Y., assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application September 7, 1950, Serial No. 183,556 4 Claims. (Cl. 137---512.1)

This invention relates to fuel injection pumps for compression-ignition engines.

In fuel injection pumps of the class wherein the injection plunger has a controlling edge to determine the effective length of the pump stroke and a spring controlled displacer type check valve which closes upon the spill-back of fuel through the plunger, the rate of such closing is so rapid that a negative pressure wave is induced in the fuel delivery pipe during the closing movement which is characterized by a curve having a very steep slope. When the valve strikes the seat at the end of the closing movement, a positive pressure wave is induced in the fuel delivery pipe. Both the positive and negative waves travel at the velocity of sound through the delivery pipe. These waves, upon reaching the injector, disturb its normal intended performance. The negative wave results in the passing of combustion gases from the combustion chamber past the fuel injector seat into the nozzle chamber thereby caus ing deterioration to the injector. The positive wave results in a re-opening of the valve in the fuel injector thus allowing fuel to pass into the combustion chamber under unfavorable conditions.

The principal object of the invention is to provide means to control the velocity of the seating movement of such a delivery and check valve and also to cushion or minimize the force with which the valve strikes the seat, thereby to avoid jarring the pumping mechanism and also to change the slope of the pressure waves to eliminate their objectionable features. A more specific object is to provide such a valve with a dash pot device to accomplish such purposes. Still another object is to provide such a valve with a dash pot device, and having an internal relief valve to minimize retardation of the reverse action of the dash pot. Other and further objects of the invention will appear from the following description, the accompanying drawings and the appended claims.

In the drawings, Fig. 1 shows a fragmentary sectional view of a fuel pump assembly, the injector and delivery line being diagrammatic; Fig. 2 is an enlarged view of the valve in its housing; and Fig. 3 is a sectional view of the valve with'the relief valve illustrated.

In the drawings, the invention is shown applied to a fuel injection system for a compressionignition engine. Casing H) has an axial bore H in which is arranged a sleeve 12 to provide a cylinder l3 for pumping plunger I4, the latter being reciprocated in the cylinder in conventional manner by the alternate action of a cam shaft and a return spring, not shown. Disposed in bore I I in contiguity with sleeve [2 is a flanged valve housing member l5 which is maintained in position by plug it, such plug being threaded into the casing. Housing I5 (Fig. 2) has a central bore [1, a conical valve seat [8, and a cylindrical duct l9 which connects bore i i to cylinder [3. Delivery valve 20 is arranged in bore I1 and extends into duct :9. Annular sealing gasket 2| is disposed between flange 22 of housing l5 and the inner end of plug It.

Fuel is supplied under pressure to cylinder i3 from an outside source through annular port 23 and radial passages 24. Plunger It on its upward stroke forces fuel from cylinder 13 through duct l9, valve 20, chamber 25, passage 2E, and delivery line 21 to the fuel injector 28. Plunger M, which has a constant stroke, is provided with a helical edge 29 of conventional construction. Edge 29 controls the effectiveness of the piston stroke by providing for a spill-back of the fuel from cylinder l3 through radial passages it and port 23. The amount of fuel supplied to the injector will be varied according to the position of the helical edge of the plunger as the latter may be controlled by the engine governor (not shown). Valve 20 is normally maintained upon its seat 18 by return spring 353, the latter being preloaded in chamber 25 between plug it and valve flange 3|. Discs 32 of desired thickness are inserted in chamber 25 at the top of spring 39 upon original assembly in order to adjust its tension. Other suitable means to provide such adjustment will suggest themselves to one skilled in the art.

Valve 20 has a main body 33, a cylindrical flange 3! connected to the body by a portion 34 of reduced diameter, a conical shoulder 35 for seating purposes, and an extension 36 beyond the conical seat connected to the main body by neck 31. Valve body 33 is fluted to provide lands 38 to guide the valve in bore I1 and also to provide longitudinal passages 39 to permit the transfer of fuel therethrough. Extension 36 is likewise fluted to provide guiding lands ll] and fuel passages 4|. Extension 35 also includes .a cylindrical portion 42 of reduced diameter adjacent neck 31. The peripheral surface of portion 42 is smooth and is spaced slightly from the wall 4-3 of duct 19 when the valve is moving to seated. position (see Fig. 1). A restricted annular passageway 44 is thereby provided for purposes hereinafter more fully described. Cylindrical flange 3| is precision machined to form a close sliding fit with bore [1 thereby to prevent the passage of fuel through the bore whenever the flange is positioned therein. As appears from an inspection of Figs. 2 and 3, the axial distance between flange 3| and seating shoulder 35 is less than the axial distance from the delivery end ii'a of the bore l1 and the seat I8.

When the spill-back action through plunger I 4 begins, pressure in the fuel column extending from the plunger to the injector will drop in- 3 stantly, and valve will move toward its seat in response to the bias of return spring 313 and the expansion pi the fuel compressed in the column. v Dur'ng such valve movement; fflang'et'i will entrap fuel in bore [1. Such fuel has no means of escape except through duct 59, but access of the fuel to the duct is only throug'h the drical extension on the body beyond the seat ing portion and reciprocable in the second bore, the flange havinga fluid sea-ling it in" the first Horaand fie'ing zspaced from the s'eatihg portion at a lesser distance than the distance between the valve seat and the delivery end of the first bore so that when the valve is moved toward restricted passage 44. A dash pot devise-is mus 7 produced in which a fluid cushion is prgvided be; I

tween the valve and its seat; an; the motidnpf the valve is retarded, thereby avoiding thegjarring effect which normally resultsrto the pump assembly when the valve strikes the seat: The slope of the negative pressure wave willjhereby' wan 1 as be desirable ating 'at high speeds, however; it'm'ay be; ecto eliminate such retardation Tojacc'ompli's'h -thisjres'ullt, a reli'ef lvalve, generally iridicatedl'atf itiffil ig. 3) is providewwithin valve 20. 'siieh'rener valve be j'f conv'entionahdes n; 'jas, ff or etriple, comp 'is'ing a'ballfijdispose'tl upon con cal seat 4110 mec'at the endlfof met pass eaten-d a return spring "49 arrange injto j fac fend rnain taind 1' against the baufpy ith'e nutty threaded n t 'v'alve'fi'ng'e 3|, sprifigfijs'oirrsj only slight qpi k q t the moyementf t" tense that fueli'ri duet r9 willpa'ssthiou'gh' ssag'eft a 'bqfe 50 and radial ports 5 2 to relieve the "vacuum or reg n, b l iwf i-e ur just .d .b d th t ges er'reiie ve es'v vill radnysh'ggest them lyl il -qfin l l .1]. u

housing spaced ata predetermined distanceifr'om the delivery' end of said" bore,a secondbor e iaxially'jal iigned with the first bore; and a valve re- 7 cipr'bcajbly guided in the bores}: said valvehav ing mainbody reciprocable in the first loore, a

passag nithe pody to 'permittloe 'rnovement or body, a seating portion on'thebody,"anda cylinvalve s'esta 'cositieh the flange enters the bore begf ore the valve seats thereby to force fluid in the firstbore -past,the seat, and the cylindrical extension'being spaced from the wall of the second bpre tojorm a restricted passageway to retardtlie canteen-the fluid thus forced by said flangesdtthat the fluid thus entrapped will cushion the valve in its seating movement and damp surges arising in the fluid column.

2. A deliveryyalv'e' apparatus for'c'ont' lliiig; the intermittent new of "'9; fluid domain "from a pressure cylinder to 'a point of use comprising a housing, 'a first :bo'i'e therein, "a second bore" aligned with the first tore, a valve seat Shaded the bore, and a passage between the bore and at ainei r mm d d stan unre eemed f th 'f r tf ieja va ve a n 1 I i gbb and a return spring fo'r the valve,'thevalve Hav- 'in'ga body slidably mounted in the borefa fluid passage through the body, a cylindrical flange onthe body having afiuidsealing fi't'with the flrst'bo re being sp acedlfrom the seatin portion at a lesser distance than the distance between the valve seat and the delivery endof the firstbore, said valve being adapted tbj fov out or the flr'stibore 'during the passage of fluid therethrough in onedir'ection but to return thereto upon th'e completion Lof suchtassage to capture fluid insaid bore an-extension on th e-biody reciproca-ble in bore, -a fluid {passage through the ezitension; and a cylindrical-porat h w s i it we 'e f ac 6 which is; spaced jrornithe wall of the second bore to for rn a i estricted'annul ar fluidpassage-asthel extension reciprocatestherein thereby to provide a da h, to retard Seating em n -p the jalveland to damp surges arising'in the fluid column after the completion of fluid passage.

3. A valveaccording to claim 1, in which the valve is provided with relief means adapted to establish;communication,ibetween the fluid coln j po sitesige f e valve s twh t e fluid is, passing from the pressure cylinder to the point; of use.

i A. val :efaccordin g to claim 1 providedwith a'reliei valve within its body comprising 'a -duct' ineQmInunicatiQn with the fluid supply,; a bore in communication with the duct, a ball valve bettweenthe duct andthe bore, a return spring -in the" columnibeyond the valve seat whereby communication is established through the valve when fluid passes from the pressure cylinder-to the point of use.

'wILLiAM sic-irons.

"afeiiices Cited in: the-hie of this patent:

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