US2068196A - Pump - Google Patents

Description

Jan. 19,` 1937. G. w. RAWLlNGs v 2,068,196

' PUMP Filed July 1o, 1935 2 sheets-sheet 2 w @V NNN mf A@ k v FMR/ m.

Patented Jan. 19, 1937 l PUMP George William Rawlings, Park Hill,

Kenilworth, England v Application July 1o, 1935 serial No. 30,606 In Great Britain December 14, 1934 s claims. rc1. H4)

10 the contained 'volume of thetube is alternately 'increased and decreased or is alternately increased or decreased and restored to its initial Y volume.

With pumps of the' said kind it is found that when used fordelivering liquid at relatively high pressures andA under the same conditions of operation'a constant volume of delivery for each pumping cycle is vnotattained owing to the compression of the liquid or of air which may have entered the tube or of air occluded wit-hinthe S liquid. As a consequence pumps of this kind have not been very successful when utilized forv the injection of liquid fuel for direct fuel injection internal combustion engines and the present invention has for its primary object the provision of an improved liquid pump which retains .the simplicity ofpumps of the kind under rview but which at the same time ensures the delivery of constant volumes of liquid ateach pumping cycle 3l) under the same conditions of operation.

A further object of the invention is the provision of means which ensures an abrupt termination to the discharge thereby rendering the pump \parti cularly suitable for the injection ofl fuel in.

' 35 internal combustion engines of the direct Ifuel injection type. Y

The invention consists 'of an improved pump comprising a tube,means for effecting an alternate flexing, bending or twisting of the said tube 40 so as to engender a pumping effort by varying the contained volume of the bore of said tube,l a pumping chamber, a pump body having therein a passage placing thev said chamberin communication with a source of supplyand with a discharge line and with an orifice opening into the pumping chamber, valve means vfor controllingv the supply of liquid to said passage and the fdischarge of liquid -therefrom, a mercury'iilling for saidl tube, free from air, a re'silientdiaphragm dividing the aforesaid pump'ng chamber from the tube and consequently from the adjacent end of the mercury column, said diaphragm normally occupying a. position in which the volume of the pumping chamber is slightly in excess of the f5 maximum volume of liquid required to be ejected drawings which villustrate at a delivery operation and under theinuence of the pressure generated in the tube, closing the aforesaid orice.

The invention will now be described with par-` ticular -reference to the accompanying sheets of- 5 the invention in its application to' a liquid fuel injection pump for use with an internal combustion engine of t-he direct fuel injection type.

Figure 1 is a vertical section lof the improved pump.V

. Figure 21s a composite fragmentary view illustrating diagrammatically the position occupied by the parts immediately prior to injection,I the 15 portion of the pump containing the diaphragm referred to hereinbefore being shown on an enlarged scale.

Figure 3 is a similar view to Figure 2 but show- "ing the positionsy occupied by the parts at the 0" completion of an injection. -As illustrated in the drawings, the improved injection pump comprises a curved metal walled tube l of an elliptical shape in cross section, said tube being closed at one end and having pivotal 25 connection adjacent to this closed end to the outer end of a lever 5 which is fulcrumed adjacent to its other end on a ball Abearing race' which is mounted on a fixed spindle 1. This lever 5 is provided intermediatey the ends with' a pro- 30 jection 5F which co-operates with a cam 8 mounted onl a shaft .9 adapted to be rotated by the engine. The other end ofthe tube 4 to that mentioned terminates in an enlarged portion' 4a having therein a centrally disposed aperture which 35 communicates with the bore in the tube 4 the said aperture .being closed by a removable plug l0. The bore in the enlarged portion 4B has communication by way of a passage 4b with an inclined passage Iln formed in a body Il supported from 40 the base I2 of the pump said passage IlEt opening into a. chamber Hb. The body 'Il is provided with a cylindrical recess which is symmetrically disposed relativelyfto the chamber Ilb but of greater diameter. The walls of the cylindrical' 45 recess are tapped for .the reception of a block I3 having therein a vertically disposed passage I3, This passage l3l'communicates by way of a onewayv valve Il with a passage leading to the discharge line I5 from a pump, hereinafter termed 50 the primary pump, which is not shown but which is generally 'similar to the injection pump illustrated hereinbefore and which primary pump delivers fuel from a reservoir to the aforesaid injection pump. The liquid is Supplied. to the injection pump through a nozzle I 6 which has a discharge orice having a known coeiiicient of discharge so that by varying the pressure of the supply as delivered by the primary pump the quantity of fuel supplied to the present pump,

.parts by a dished spring steel diaphragm I9 and the upper part of the said chamber I Ib is termed hereinafter the pumping chamber llc.

The lower part o f the chamber I Ib, the passage II, 4b' and the bore of the tube 4 are lled with mercury which is freed from air.

The volume of the pumping chamber IIc is slightly greater than the maximumquantity of liquid which is capable of being delivered at a pumping cycle.

'I'he operation of the pump as shown in the accompanying drawings is as iollows:- l

Liquid is supplied at a controllable pressure b the primary pump to the pumping chamber II by way of the nozzle I6, the one way valve I4 and the passage/A3. 'Ihe liquid is admitted to the pumping chamber IIc .during that part of the cycle when the engine driven shaft 9 is rotating the cani 8 from the initial position shown in Figure 3 to that shown inFigure 2. During this ad' mission period the tube 4 is flexed by the lever 5 in such a manner that its `contained volume is increased thus permitting the Vdiaphragm I9 to assume the position shown in Figure 2 and thus providing capacity for the inlet of fluid to the pumping chamber IIC.

The quantity of fluid supplied to the p pingv chamber IIc din-ing this admission pe d depends not only upon thev capacity so provided but also upon the pressure maintained by the primary pump and the coeiiicient of discharge of the nozzle I 6. When the further rotation of the shaft 9 completes the revolution and brings the cam 8 to the initial position shown in Figures land 3 the tube 4 is .permitted to resume its initial form whereupon its contained volume is decreased and the diaphragm I9 is subjected to the consequent pressure of-the mercury lling and vis thereby constrained toeject theliquid from the chamber II, this ejection1 continuinguntil the diaphragm I9 abuts the face oi the block I3 as shown in 4Figure 3 whereupon the ejection terf minates'abruptly. This ejection of the liquidv from the pumping chamber IIc is of course the injection of fuel to the engine.

.It will be `appreciated that under any given conditions of working constant quantities of liquid are` supplied to the injection pump and that constant quantities of liquid are forced by the injection pump to the fuel injector.

'Ihe tube .I may be filled with' liquids having a high bulk modulus other than mercury or with a plastic material provided of course that the liquid or plastic material employed is not subject to any solvent orother undesirable action with the medium being pumped.

In a modification not illustrated a iiat diaphragm I9 maybe employed and the lower end of theblock I3 given a concave formation.

It will vbe obvious that a battery of pumps may be operated from a common vengine driven shaft 9. Y

What I claim isz- 1. A pump comprising a tube, means for effecting an alternate flexing, bending or twisting of the said tube so as to engender a pumping eiort by varying the contained volume of the bore of said tube, a pumping chamber, a pump body having therein a passage placing the said chamber in communication with a source of supply and with a discharge line and with an orifice opening into the pumping chamber, valve means ior controlling the supply of liquid to said passage and the discharge of liquid therefrom, a mercury filling for said tube free from air.' a resilient diaphragm dividing the pump chamber into two parts one of which is in communication by way of the aforesaid orice with the passage in the pump body and the other part of which is in communication with the tube and is lled with mercury, said diaphragm normally occupying the position in which the volume `of the pumping chamber is slightly in excess loi! the maximum volume of liquid required to be ejected at a delivery operation and under the iniiuence of the pressure generated in the tube closing the aforesaid orifice to eiiect an abrupt termination of a discharge operation.

2. A pump comprising a tube, a power source, means driven from said power source for periodically bending the tube so. as to engender a pumping effort by varying/the contained volume of the bore of said tube, a pump' body, a pumping chamber formed in said pump body, a plug adapted to flt within safd body and having therein a passage placing the pumping chamber in communication with a source of supply'and with a discharge line and with an orifice opening into the pumping chamber, valve means Vfor controlling the supply of liquid to said passage and the 'discharge of liquid. therefrom, a mercury iilling for said tube,j and a resilient sheet steel diaphragm dividing the aforesaid pumping chamber into two parts one of which is in communication by way of the aforesaid orifice with the passage in the plug and the other ofwhich is in communication with the tube and is filled by mercury, said diaphragm normally I occupying thepositionin which the volume of the pumping chamber is slightly in excess ofthe v `maximum volume of liquid required to be ejected .at a delivery and under the influence of the pressure generated in the tube closing with a snap action the aforesaid orifice in order to eiect an abrupt termination of the discharge.

3. A pump, according to claim 2, wherein the diaphragm' is dished and coacts.with the flat end of theplug for the purpose of enhancing the speed of closure of the orice by the diaphragm.

GEORGE WILLIAM RAWLINGS.

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