US2810375A - Injection pump for internal combustion engines - Google Patents

Description

Oct. 22, 1957 K. FROEHLICH El' INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES I SSheetS-Sheet 1 Filed April 13. 1953 lllllllllllh 1 NP 'f Oct. Z2, 1957 K. FRoEHLlcl-l ETAL 2,810,375

INJECTION PUMP EoR INTERNAL coMBusTIoN ENGINES Filed April 13. 1953 5 Sheets-Sheet 2 Oct. 22, 1957 K. FRoEHLlcH Erm. 2,810,375

` INJECTION PUMP Fox INTERNAL coMBusTloN ENGINES.

med April 1s. 195s s sheets-sheet s 76i l f 70 74' l G u EQ United States Patent INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES Kurt Froehlich, Emil Grieshaber, and Milton Leichtfuss, Milwaukee, Wis., assignors to Nordberg Manufacturing Company, Milwaukee, Wis., a corporation of Wisconsin Application April 13, 1953, Serial No. 348,468

13 Claims. (Cl. 123-139) This invention resides in the field of fuel pumps or fuel injection apparatus and mechanism and is an improvement over prior pumps which are adapted to inject various types of fuel.

More specifically a primary object of this invention is an injection pump of the dual fuel variety with means for selectively using the pump for the injection of either pilot oil or diesel fuel oil.

Another object is a pump of the above type which is adapted to inject a constant quantity of fuel at a variable time in the engine cycle or a variable quantity of fuel at a predetermined time in the engine cycle.

Another object is a fuel pump adapted to displace a constant quantity of fuel at a variable time in the engine cycle under one set of desired operating conditions and under another to displace a variable quantity of fuel beginning at an approximately constant or xed time in the engine cycle.

Another object is an injection pump of the plunger variety which is adapted to be used on the cylinders of an engine to inject quantities of fuel that can be standardized or equalized for all of the cylinders.

Another object is a fuel pump of the plunger variety adapted to displace a constant quantity of pilot fuel at a variable time in the engine cycle, the quantity for each cylinder of the engine being standardized or equalized by a variable capacity reservoir within the pump, and the pump being further adapted to inject a variable quantity of diesel fuel beginning at a constant time in the engine cycle.

Other objects will appear from time to time in the ensuing speciication and drawings in which:

Figure l is a vertical sectional view with parts broken away illustrating this invention as applied to a pump of the plunger variety;

Figure 2 is a development of the surface of the pump plunger shown in Figure l;

Figure 3 is a sectional view taken alongline 3 3 in Figure l;

Figure 4 is a sectional view taken along line 4-4 in Figure 1;

Figure 5 is a vertical sectional view similar to Figure 1 and depicting a modification of this invention;

Figure 6 is a development of the pump plunger'shown in Figure 5;

Figures 7 through 10 are perspective views partly in section showing the various positions of the plunger shown in Figure 5 during its operating or fuel injecting cycle; and

Figure ll is a sectional view along line 11'-11 in Figure 5.

In Figure l we have shown a dual fuel pump with a housing 1G which encloses abarrel 12. Aplunger 14 is mounted conveniently Within the barrel and is adapted to rel. Suitable inlet connections, indicated generally at 20 are provided for the entrance of the fuel and are con nected to thefuel chamber 16 in an appropriate manner. Acontrol sleeve 22 is positioned around the lower end of the barrel and plunger and has agear ring 24 adjacent its upper edge which meshes with acontrol rack 26 in a well-known manner. The lower end of the control sleeve has a rectangular or closedportion 28 which mates or coacts with asimilar portion 30 on the plunger, so thatv any rotation imparted to the sleeve by the rack will also be imparted to the plunger. The plunger is biased downwardly by aconventional spring 32, which engages aplate 34 aflixed to the lower end of the plunger. The plunger structure in the above-described mechanism is retained within the housing by aplunger guide 36 andsnap ring 38.

The plunger is reciprocated by acam 39 on the cam shaft in a conventional manner.

Adelivery valve holder 40 is removably secured to the top of the housingA by any conventional means and has adelivery valve 42 and itsoperating spring 44, the top of the holder being provided with acoupling 46 which connects the pump to asuitable outlet 48.

In Figure 2 we have shown a developmentkof the surface of the plunger in Figure l, this surface being primarily composed of two portions orhelixes 50 and 52. Thehelix 50 is adapted to inject pilot fuel only when the engine is being operated on a fuel such as natural gas for example, whereas thehelix 52 is adapted to inject fuel oil which may be ignited by the temperature of compression, which is not the case with natural gas. Thehelix 50 has a leadingedge 54 and atrailing edge 56, which are essentially the port closing and port opening edges of the helixes. It should be noted that these two edges are substantially parallel and are adapted to coact with theopenings 18 in the barrel, so that at any setting of therack 24, the reoiprocation of the plunger with thehelix 50 in alignment with ports Will result in the injection of a constant quantity of pilot fuel. Theport closing edge 54 is slanted so that the time of the berginning of injection during the upward movement of, the;A plunger may be varied. Thus this helix is adapted to inject at all times a constant quantity of pilot fuel but at a variable time in the engine cycle.

Thehelix 52, on the other hand, has similar leading4 Thus we have a plunger surface with two helixes thereon, one helix being adapted to inject pilot fuel Yat a variable time during the engine operationlbut always a xed quantity and, the other helix being adapted to,

inject diesel fuel beginning at a constant or fixed time during the engine operation but a variable amount or quantity, depending upon the selective positioning of theY rack 26.

Due to the inaccuracies in machining and generally throughout the entire manufacturing process, the pilot fuel injection helix have been found to vary slightly fromV one pump to another and itrhas been very diicult to standard or equalize the quantity of pilot fuelV that is being injected from each of the pumps on the cylinders of an engine, it being understood that one such pump will be used with each cylinder. i It is the rule, rather than the exception, that one pump will inject'aslightly different quantity of pilot fuel than another. Consequently, f

' .a multi-cylinder engine will operate somewhat irratitfmallyg To counteract this,I we have provided in the delivery valve holder 40 adisplacer piston 62 which is in communication with the bore of the barrel by anorilice 64. A. manually variable.stop mechanism.l .66 is. positioned; aboye. the: .displacement piston .and fhas anlabutment' on` the lower end. .thereof which can lbe.differentially positioned with relation .to the. displaeer pistonby rotation of thestop mechanismA 66. Thefpistonf. is biased. downwardly by a. suitable spring 7,0it1-being understoodthat the. manuallyadjustable stop mechanism 66 isY suitably threaded. or otherwiseadjustably secured-.in the-holder 4l).

Thus. by proper regulation.of the spring 7.0 during the initial; portion; ofv the upward mou/.erneut` of' the plunger, the. displacer piston will move-upwardly .untilit the4 abutment .68. and. during Vupward movement: fuel will not be pumped.v past the delivery value.. .As Ysoon as` the piston `engages-.the abutmentthe remainder ofthe. plunger stroke will effect vthe normal fueliujection process. mechanism.. ,the quantityk of fuel-retained` in the; chamber of the movable displacer piston. may be. yaried and as.. this quanti-ty is subtractedV from thetotal quantityl of fuel in the barrel.. the quantityof fuelv injected may be` accurately and precisely regulatedand determined.

Y The upper portion of `the displacer piston chamber is in communication with the mai-n fuel,l chamber by a suit.-able passage 72 to prevent the creation of .a vacuum behind the displacer piston.

The orifice 64- is substantially smaller inarea: than the piston chamber and gives a. dampening; ejfect. to the oil moving into and-.out of the pi-stonchamber.

In Figure `6 a development of the helixes: of. the: plunger of Figure is shown aud.x it will be noted that these helixes are similar to but vary.- in certain respects from the: Figure 2 development. To begin willig. in Figure Z thereis: only one set of helixes. which coactiwiththe port; However, in Figure 6, we vhave `shown two sets .of '.helixes which. are substantially identical with. eachother. Each of the sets of helixes hasoneV helix 74 forv pilot fuel injection and anotherhelix 76 forY diesel fuel injection., the port closing and openingl edges, for'the pilot fuelhelix being substantially parallel; Whereas, for. thediesel fuelv helixY 76, the. port closing, edge. is. substantially' horizontal and the port openingledge is disposedy at a1 decided angle and is. orientedgenerally in the direction of the edges on the pilot fuel. helix. Thus the plunger in Figure 5 is adapted to inject a fixedquantity of pilot; fuel at: avariable time in the. engine cycle. and also to.y injectia variable quantity .of diesel fuel beginning: .at a. -xed time in. the. engine cycle.

In Figures 7 and 8 we have .shown the. barrel and plunger duringv the injection of diesel .fuel and. the;ports 78 are closed and opened by the helix. 7.6, it:b.eing understood that a helix coactsy with, each; port.. Figure 7 depicts the upward movement of the plunger. just. prior to the closing of theports 78 and Figure 8. shows 'approximately theupper limit of theplungerfmovement. after the port opening edge. has passed the ports. Figures 9 and 1.0, show the same -plunger asinV Figures 7. and 8,. however,..it has been rotated bythe raclt to inject. pilot fuel and helixes 74- are positionedato close` and; open theports 78. The port closingris delayed, as' shown-.im Figure 9, during the. upward.' movement' of the plunger and the port opening occurs much sooner, as shown in Figure. 10. The Figure 5 plunger also varies lfrom the Figure. 1 plunger in that pressurerelease iS .effected through the. tapered channel 8.0. between the two; helrxes; whereas, the Figure 1 plunger requires; acentrali borefor-hole- 82.

The displacer piston-84 in- Figure 5? ia: removed. sub.- stantially from the plunger and. barrel andrcomnnlnicates with the chamber through an. openinggoahe. upper portion, of the piston chamber being ineommunieation: with the' oil chamber through anotherpassage 88. An. abutment 9.0 is also provided for this piston; andis; adapted: for. manual or automatieadiustmentcbany.cunyentional By manual or automatic adjustment of the stop.

mechanism shown generally at 92. The piston is biased downwardly by aspring 94 the tension of which can be adjusted by theadjustable mechanism 92. The opening orpassage 86 gives the same dampening effect to the moving oil as set forth with reference tooriiice 64 in the modication of Figure 1. i

The use,V operation and function .of thev invention are as follows.n

Conventional' engines are adapted' to operate on the dualffuel principle, meaning that; under; certain` conditional natural. gas will bmdrawn into: they cylinders, and' compressed.. However, .ther-elevated temperature gained by compression of the ,gasisnot sufficient to, ignite. it consequentl'y, a pump is generally` provided to inject what is termed pilot pilotoil.. 'lhesame engine may the. cylinders to.' eleetA combustion and: the ensuing power stroke. expansion.. t

We have designed a fuel injector pump which is: basi-- cally similar to. conyentional pumps. However, our pump is designed. to.; inject either .pilot fuel' or diesel fuel, the.

pilot fuel, when; used., being .injected at: a variable` time but in a fixed quantity, and the diesel fuel, when used', being;injected` beginning; at; a linedatime. during the engine cycle butin- Va. variable quantity.

The. Figure Linjector. pump represents apumpr with a large plunger diameter anda .short stroke and FigureV 5f shows apump witha small plunger diameter and a long stroke.

The Figure 1 injector; pump is Vbeing usedA with four cycle engines, the. Figure. 5.; pump` with two cycle engines'.

`Becaulse the camshaft of the four cycle enginev runs half the speed of the crankshaft, usually the cam rise. per degree. of cra-nkangle .is-l less on four cycle. engines than;- on. two cycle engines which. leads to a. relatively" shorter strokeof the fuel pumps onfnur-cycle engines..

Note in Figure 1 that; the angle-.of thet port closing andv port )openingI edges on the pilot fuel helix are not as steep as thefclosing; surfacesI of the pilot'. fuel helix in Figure. 6, this being caused bythe short stroke for the Figure 2` fourstroke cycle plunger and theV long stroke for the Figure two stroke cycle plunger.` Ln Figure 2, as the angleof the.- edges is: not so1steepthe two helixes can be joined together.. However, in-.Figure 6,. dueto the steep angles required, the two helixes must be separated so that a. satisfactory operating range can be acquired for both the diesel and pilot. fuel injection.

Due to the slight. inaccuracies inthe plunger belixes, inaccurate quantities. of pilot fuel'. will, be injected fromY one pump to another. To standardize the pumps for all' of the cylinders. onan. engine. the displacer pistons on all of the pumps can be adjusted,s,0v thatthe quantity of pilot' fuel injected. by each ofthe; pumps will be approximately the same. Even though we have shown the `clisplacer piston adjusting mechanismy as. being manually operable, it should be understood that this mechanism could. bev automatically or semi-automatically accomplished.

Whereas we haveshown. and described a preferred form of our invention and one modification thereof; it should be understood that various other alterations and substitutes. can` be made-l wh-ichwould not, depart from the: fundamental theme of the invention. ,and we desire` that our invention be unrestricted except by the appendedy claims...

We claim:

1. Eon-use. inafuelinjection-fsystem, a-.fuel pump comprisiugA aA housing definingA a fuel. chamber with a fuel inlet .andoutlet, a. plunger-.movably mounted. within saidy housing .and adapted.. to reciprocate thereinso as. to displace fuel from the chamber .to theV outlet, the plunger having; azhelixed; sunface opposed tothe inlet, means. forrotatingIhe plunger so. asr to presentsdifferent partsof' the helixed surface to the inlet, and means for regulating the capacity of the chamber so as to vary the quantity of fuel discharged to the outlet, said last-mentioned means comprising a variable capacity reservoir, said reservoir being in communication with the chamber through a restricted dampening orifice.

2. In a fuel pump, a housing defining a fuel chamber with the fuel inlet and outlet, a plunger movably mounted within the housing and adapted to reciprocate therein so as to displace fuel from the chamber to the outlet, means on the plunger for regulating the quantity of fuel injected including at least two helixes which coact with the inlet, one helix being adapted to inject an approximately constant quantity of fuel at a variable time during the plungers movement and the other helix being adapted to inject a variable quantity of fuel, and means for regulating the capacity of the chamber so as to vary the quantity of fuel injected, said last mentioned means including a variable capacity reservoir in co-mmunication with the chamber through a restricted orifice.

3. In a fuel pump, a housing defining a fuel chamber with the fuel inlet and outlet, a plunger movably mounted within the housing and adapted to reciprocate therein so as to displace fuel from the chamber to the outlet, means on the plunger for regulating the quantity of fuel injected including at least two helixes which coact with the inlet, one helix being adapted to inject an approximately constant quantity of fuel at a variable time during the plungers movement and the other helix being adapted to inject a variable quantity of fuel, and means for regulating the capacity of the chamber so as to vary the quantity of fuel injected, last said means including a variable capacity reservoir in communication with, the chamber, and damping means in the line of communication between the reservoir and the chamber so as to dampen the flow of tiuid therethrough.

4. In a fuel pump, a housing defining a fuel chamber with a fuel inlet and outlet, a plunger movably mounted within said housing and adapted to reciprocate therein so as to displace fuel from the chamber to the outlet, and means on the plunger including at least one helix to displace fuel from the plunger to the outlet, a variable capacity reservoir in communication with the chamber adapted to receive a variable quantity of fuel during only the initial effective portion of the plungers pumping stroke, and damping means between the reservoir and the chamber adapted to dampen and restrict the ow of fuel between the chamber and reservoir.

5. In a fuel pump constructed for supplying liquid fuel to a dual fuel engine or the like, a housing defining a fuel chamber with fuel passages including an inlet and outlet, a plunger adapted to reciprocate in the chamber of the housing to displace fuel, that has entered the chamber from the inlet, to the outlet, means on the plunger for regulating the quantity of fuel displaced, including at least two helices disposed to coact with one of the passages, one helix being constructed to inject an approximately constant quantity of fuel at a variable time during movement of the plunger, the other helix being constructed to inject a variable quantity of fuel, means for rotating the plunger so as to selectively bring different portions of the helices into cooperative relationship with the said one passage, the helices being arranged, relative to each other, so that the position of maximum retard of the said one helix is relatively adjacent the position 6 of the minimum fuel delivery of the said other helix, the helices being constructed so that the quantity of fuel injected by the said one helix, in any cooperative position with the said one passage, is less than the quantity of fuel injected by the said other helix, in any cooperative position with the said one passage.

6. The structure of claim 5 further characterized in that the said other helix is constructed and arranged to inject a variable quantity of fuel at an approximately constant time during the movement of the plunger.

7. The structure of claim 5 characterized by and including means for regulating the capacity of the chamber so as to regulate the quantity of fuel displaced to the outlet, including a variable capacity reservoir in communication with the chamber, the maximum capacity of the reservoir being substantially less than the capacity of the chamber, the variable capacity reservoir being constructed to regulate the capacity of the chamber so as to vary the quantity of fuel injected by the plunger.

8. The structure of claim 7 further characterized by and including means for regulating the capacity of the reservoir so as to vary the quantity of the fuel injected.

9. For use in a fuel injection system for an engine or the like, a fuel pump comprising a housing defining a fuel chamber with a fuel inlet and outlet, a plunger movably mounted to reciprocate in the housing to displace fuel from the chamber to the outlet, the plunger having a helixed surface, means for rotating the plunger so as to make different parts of the helixed surface effective so as to displace variable quantities of fuel from the chamber to the outlet corresponding to each load on this engine, and movable means for regulating the capacity of the chamber to vary the quantity of fuel discharged to the outlet for all loads on the engine, said means being unaffected by the rotary position of the plunger, said movable means including an adjustable stop mechanism for positively regulating the position of extreme movement of the movable means.

l0. The structure of claim 9 further characterized in that said last mentioned means includes a variable capacity reservoir iu communication with the chamber.

ll. The structure of claim l0 wherein said reservoir includes a spring biased piston.

12. The structure of claim ll wherein said st-op mechanism is manually operable so that it may be differentially positioned with respect to the piston to determine the capacity of the reservoir.

13. The structure of claim l0 further characterized by and including a fluid flow dampening orifice between the Variable capacity reservoir and the chamber.

References Cited in the tile of this patent UNITED STATES PATENTS 2,019,650 Bischof Nov. 5, 1935 2,223,755 Dillstrom Dec. 3, 1940 2,414,696 Miller Jan. 21, 1947 2,502,989 Rathbun Apr. 4, 1950 2,544,561 Meyer Mar. 6, 1951 2,612,842 Steven et al. Oct. 7, 1952 2,686,503 Reddy et al. Aug. 17, 1954 FOREIGN PATENTS 448,175 Great Britain June 3, 1936

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