US2623468A - Fuel injection pump - Google Patents

Description

FUEL. INJECTION PUMP Filed April 15. 1948 GEORGE STEVEN ROY R. FRUEHAUF IN VEN TORS Patented Dec. 30,

FUEL INJECTION PUMP- George Steven, Kenmore, andRoy R. Fruehauf. Orchard Park, N. Y., assignors to Worthington Corporation, a corporation of Delaware Application April 15, 1948, Serial No. 21,246

13 Claims.

1 This invention relates to liquid fuel injection apparatus and, in particular, refers to fuel pumps providing pilot injection. This application is a continuation-in-part of application No. 709,514

filed November 13, 1946 now Patent No. 2,612,842

dated .October 7, 1952.

Though it will be obvious that it is not so limoil into the engine.

It has been found that the characteristics of the gaseous fuels in this type of engine are such that a pilot charge of injection oil is required for ignition. Since this charge is quite different than that required when the engine is operating principally on fuel oil, it has been found preferable to provide a separate pilot injection system for use when the engine is operating on gaseous fuels. It is clearly desirable to eliminate this separate system if it can be done without sacrificing operation, and an object of the present invention is to do so by combining the pilot system with the system used for regular injection of oil fuel.

When the dual fuel engine is switched to operation 'on oil fuel, by suitable means such as disclosed in said patents, it becomes essentially a dieselrtype engine. Similar problems are encountered, therefore, and one of these is noisy combustion or knocking. It may be said in ,general terms that this is believed to be caused by an excessive quantity of fuel having been injected into the cylinder, before ignition begins. This is referred to as ignition lag.

It has long been believed that this knocking" could be controlled by providing pilot injections of small quantities of fuel oil. When these ig nite, they donot cause knocks but still generate sumcient heat to ignite the main charge of fuel which follows. Thus, with regard to the main charge, there is reduced ignition lag." Total fuel injection in accordance with this-method therefore consists of two stages, first the pilot charge and then the main charge.

Control of the quantity of fuel injected in each stage is clearly desirable. This can, of course, be accomplished by two separate systems, one for pilot injection and the other for mairi injection. Such an arrangement, however, has the disadvantages of being imnecessarily expensive .and complex to manufacture and operate. Fuel pumps have, therefore, been developed which. provide both pilot and main injection, through one injection nozzle.

Considering the reciprocating plunger type of fuel pump, the rate of fuel injection is dependent upon the effective area of the piston and upon the velocity. with which it moves; and the total quantity injected is dependent upon the area of this piston and the effective length of the stroke. I In prior art fuel pumps, quantity control has centered about regulation of velocity and time. Thus, cams are often used to vary the velocity of the plunger. For pilot contro1 cams are designed to give a low velocity and therefore a small quantity of pilot fuel during the first or pilot stage. During the main stage, the cams increase the velocity to provide for a large charge. Cam

control has not, however, been entirely satisfactory because of the extremely critical dimensions required of the cam surface. Because of the effects of wear and machining inaccuracies upon the cam surface, it has been almost impossible to obtain optimum and dependable injection control.

Another method of control which is embodied in prior art fuel pumps is that of the length of the stroke. This is used in the interrupted injection type of pump, for instance, where the plunger has a short stroke for pilot injection whereupon thefuel is bypassed for a brief period and then a longer, main stroke occurs. It will be recognized that unless this bypass control is combined with a. cam that only the total quantity injected, and not the rate of injection, is controlled. When it is combined with a cam to control the rate, it adds the disadvantages just mentioned and still has its own feature of interrupted or discontinuous injection which is often undesirable.

It is an object-of the present invention to provide a fuel pump which, in general, is not subject to the disadvantages of the prior art devices and which, in particular, has two rates of injection, a pilot rate and a main rate, which are not basically controlled by cams or bypasses.

When the fuel pump is used on a dual fuel engine which is operating on gaseous fuel, the main charge is not required and it is, therefore, an object of the invention to provide a fuel pump having two injection stages, one of which may be rendered inoperative.

3 in contrast to the prior art referred to, the present invention contemplates control of the rate of injection by means of the piston area. In

. order to provide two injection stages, the present invention has two pistons of different areas. The piston of smaller area is used for the pilot injection. A feature of the invention makes it possible to use'both pistons for the main charge. It will thus be realized that the invention provides a relatively slow rate of pilot injection and a high rate of main injection. Means are also provided to connect the main piston to a low pressure area so that its effective stroke can be varied from a maximum when the engine operates entirely on oil fuel to zero when the engine operates entirely on the channel 23 is in line with the hole 'or suction opening I no oil will be discharged from the cylinder 36 as it will always be connected with the suction chamber 1 through the helical channel and the channel or cut-out 23.

According to the present invention means for a second rate of injection is added to the foregoing structure which may be of the well known Bosch design, as indicated. This means includes the upper housing I which is connected in fluidtight relationship to the liner II by the ground joint and to the housing 3 by the soft gasket 30 and the bolts 32. This housing has a bore 34 which is coaxial with the liner bore 5. If desired, the lower end of this bore may be adapted as shown to form an extension of the liner 6 bore 5 above the plunger 2|, this total space belower housing 3 and related elements may, if

desired, follow the design of the Bosch injection pump which is well known in the art. Thus, the housing 3 has a longitudinal bore 5 opening into a larger suction chamber 1 near the top of the housing. The chamber I is connected to a source of fuel oil by means of a passage or conduit 9. A liner II is mounted. in the bore 5 and extends through the suction chamber I so that the top thereof forms a part of the top of the housing 3. The liner II has holes I3 and I5 in its walls which connect the interior of the liner to the suction chamber 1. The axes of these holes preferably lie on a diameter of the liner.

The plunger or piston 2| is reciprocably and rotatably mounted in the liner I I. This plunger 2| has a helical cut-out 25 connected to the top of the plunger by a longitudinal slot 23. Means are provided to rotate the plunger 2| and consist of a rack I3 operating on a gear IT. The gear IT is formed upon the sleeve I1. The sleeve H has slots I I in its lower section in which arms 2| are guided. The arms 2| are formed upon or carried by the plunger or piston 2|. This construction is well known in the art and is employed in the well known Bosch fuel pumps.

The operation of the plunger or piston 2| is similar to the operation of any fuel pump of this general type. As the plunger or piston 2| moves downward to its lowest position (as shown in the drawing) oil flows into the cylinder 36 through the holes or suction openings I3 and I5 in the liner II and fills the cylinder 36. As the plunger or piston 2| moves upward oil is discharged through the holes or suction openings I3 and I5 until the top edge of the plunger or piston 2| covers these openings. Pressure then rises in the cylinder 36 and oil is discharged through theport 58, check valve 60, passages 54 and 56 and fuel line 50 to the engine (not shown). Oil continues to discharge until the hole or suction opening I5 is uncovered by the helical cutout 25 in the plunger, releasing the pressure in the cylinder-36 to the suction chamber 1 through the channel 23 and helical cut-out 25 and the hole or suction opening I5. Rotation of the plunger or piston 2| changes the relative position of the helix and the hole I5 and varies the point in the stroke of the plunger or piston 2| at which the hole or suction opening I5 is uncovered and thus varies the amount of oil discharged. If the plunger 2| is rotated until between. A loose T and slot connection 40 is shown for this purpose though any suitable means may be used. The piston or plunger 38 is preferably made of two sections which are threadably connected together as shown at 42 thus making it possible to vary the distance between the top of the piston or plunger 38 and the top of the plunger or piston 2|, or any other suitable means may be used.

The upper part of the bore 34 is enlarged to receive a spring loaded check valve 44 which prevents fiow toward the piston 38. An adapter 46 is threaded into the top end of the bore 34 and has a through hole 48 connecting the bore to the fuel pipe 50 which is connected to the pump in a suitable manner as by the union 52.

The upper housing I has a second and nonaxial bore 54. This bore is connected by a passage 56 to the bore 34 above the check valve 44 and to the top of the cylinder 36 by a passage 58. A spring loaded check valve 60 in the bore 54 prevents flow therefrom into the cylinder 36 through the passage 58.

The bore 34 receives oil from the suction passage through a passage 62. The opening 64 of the passage 62 is positioned so that it is uncovered when the piston or plunger 38 is in the lower portions of its stroke. The housing may have another passage 66 which opens at one end into the cylinder 36 and at its upper end 68 into the bore 34 below the opening 64. The piston 38 has an annular groove 10 which is adapted to communicate with the opening 68, the groove I8 being connected to the top of the piston and. thus to the open portions of the bore 34, by means of a suitable passage 12 in the piston which opens out of the top thereof.

When the fuel pump is used on a dual fuel 4 engine operating solely on gaseous fuel, the rack I9 andgear II mechanism are actuated, manually or by a suitable automatic means such as shown in the aforesaid patents to Barnaby et al. and Miller et al., to rotate the plunger 2| so that the plunger slot 23 is in alignment with the hole I5. When this is done, the top of the plunger or piston 2| is always connected to the suction chamber 1 so that this plunger will not pump oil stantially above that in the suction line 8.

absence The plunger II and piston or plunger 33 are reciprocated by any suitable means (notshown) which may include a cam. n the down stroke oil is drawn into the cylinder 38 through the hole lland into the bore 34 through passage 82. On the upstroke the oil in cylinder 38 is by-passed to the suction chamber 1 as already-mentioned. On

the upstroke the oil in the cylinder 34 is discharged through the port 84 tothe suction chamher until the plunger covers the port 34. The

pressure of the oil in the cylinder 34 then is increased by upward movement of the piston or plunger 38 until it is sumcient to'open check valve 44. Further upward movement causes oil to be discharged through the line 50 into the engine (not shown). When the piston or plunger 38 rises to the point where the annular groove 10 communicates with the hole 58, the bore 34 is connected to the suction chamber 1 through the passages 12 and 68. The check valve 44 therefore closes and pilot injection ceases.

. When it is desired to operate on two stages. i. e., pilot charge and then a main charge, the

of pilot fuel can be varied by varying the distance between the top of the piston or plunger 34 and the relief 18. The total quantity of main charge can be varied by changing the effective stroke of the plunger 2| also. This is done by rotating the plunger or piston 2| to vary the relative rotary position between the helical groove 25 and the hole l3. Rotation of the plunger 2| in one direction lengthens the stroke aligning the hole II with a point on the upper helicalboundary of the groove 25 which is more remote fromthe top of the plunger 2 I. The rotation of the plunger II in the opposite direction has the opposite effect.

The relative timing of the beginning of injection of oil by the pilot plunger. 38 and the main plunger 2| may bevaried by means of the thread- 7 ed connection 43.

piston or plunger 2! is rotated so that the slot 23 is not in alignment with the hole IS. The opening 84 and the holes i3 and i5 may be posi-tloned so that in the down piston or plunger position the opening is closer to the top of piston 38 than the holes l3 and I! are to the top of plunger or piston 2i. With this arrangement, the piston or plunger 38 will close its connection to suction first and start to pump before the plunger or piston II to provide the pilot injection before the second stage injection occurs. The differential between these two positions can be varied by means of the threaded connection 43 which will raise or lower the piston 38 with respect to opening 64 so that by variation of the relation of the ports 64 and I3 the beginning of injection of oil, or pumping by the piston or plunger 38 will be with relation to the beginning of pumping of oil by the plunger or piston 2|. When the plunger or piston 2| rises to the point where it covers holes l3 and I5, it will force oil out'of cylinder 38 through passage 58 and by check valve 68 into the bore 54. Oil flows from the bore 54 through passage 56 into the upper part of bore 34 above the check valve 44 and is forced to the engine through line 58. It will be recognized that the oil flowing through line so at this point in the second stage consists of oil from bore 34 and oil from cylinder 36. When the piston or plunger 38 rises to the position in which the groove 10 and passage 82 connects the bore 34 to cylinder 38, then oil from cylinder 38 will still be forced into the line 50 by both the piston or plunger 38 and the plunger or piston 2i as it can no longer by-pass to cylinder 33 since the pressure therein is substantially the same as the pressure in cylinder 34. Discharge of oil oontinues until the groove 25 on plunger or piston 2| comes into alignment with the hole i5. This connects the cylinder 36 through the slot 23, helical groove 25,.and hole IS with the suction cham The novel underlying principle of the present invention is sufiiciently broad to include and suggest many modifications of the particular details of construction herein described and shown in the drawing, and it is to be understood that the scope of the invention is not confined to the details shown and described but is limited only by the appended claims.

What is claimed is:

i. In a fuel injection pump, a housing having first and second bores of different diameters. plungers reclprocatably mounted in said bores, said housing provided with suction passages for oil opening through suction openings into each of said bores, said suction openings being located predetermined distances from the tops of the plungers in the extreme suction position, said housing provided with a discharge passageway for oil common to both of said bores, means for reciprocating said plungers so that they will cover their respective suction openings in predetermined sequence, one of said plungers composed of adjustably connected sections whereby the length of the plunger may be varied for varying the relative distances between the suction openings and the top of their respective plungers in the extreme suction positions to vary the sequence of covering of the respective suction openings.

2. In a fuel injection pump, a housing having first and second bores of different diameters. plungers reciprocatably mounted in said bores, said housing provided with suction passages for oil opening through suction openings into each of said bores, said suction openings being located predetermined distances from the tops of. the plungers in the extreme suction position, said housing provided with a discharge passageway for oil common to both of said bores; means for reciprocating said plungers so that they will cover their respective suction openings in predetel-mined sequence, the plunger mounted in the bore of the smaller diameter being adjustable as to length to vary the relative distances between the suction openings and the top of their respective plungers in the extreme suction positions to vary the sequence of' covering of the respective suction openings.

3. In a fuel injection pump, a, housing with first and second coaxial bores -of different. diameters, plungers reciprocatably mounted in said bores, said plungers composed of adjustably con: nected sections connected for joint axial move ment in at least the discharge direction and ad-' justable to vary the distance between the tops of the 'pIungers, said housing having suction passages therein opening into each of the bores at different distances from the effective tops of their plungers in the extreme suction positions, said housing provided with a discharge passage common to both bores for the passage of oil from the bores.

4. In a fuel injection pump, a housing having therein a first bore and a second bore of larger diameter than the first bore, a pilot plunger reciprocatably mounted'in the first bore, a main connected sections adjustable one relative to anplunger reciprocatably mounted in the second bore, said housing provided with passages for oil opening through suction openings into each of the bores, the suction opening in the first bore being closer to the effective top of the pilot plunger than the suction opening in the second bore is to the effective top of the main plunger, means for moving the plungers at such, a rate that the pilot plunger blocks its suction openingbefore the main plunger blocks its suction port and thus discharges first, said pilot plunger being composed of adjustably connected sections adjustable to vary the length of the plunger for varying the relative distances between the suction openings and the top of their respective plungers in the extreme suction positions to vary the sequence of covering of the respective suction openings and means for varying the effective stroke of the main plunger from zero to a predetermined maximum, said housing having a discharge passage'therein common to both bores for the passage of oil from the bores.

5. In a fuel injection pump, a housing therein first and second coaxial bores, said second bore being of larger diameter than the first bore, a pilot plunger in the first bore, a main plunger in the second bore, a threaded connection between the plungers whereby they are connected for joint axial movement and capable of axial adjustment relative to' each other, said housing having suction passages therein opening through suction openings into each of the bores,

having said suction openings being arranged so that the one in the 'first bore is blocked first by its plunger on the discharge stroke, said housing having a third bore therein and having a fluid passage therein connecting said third bore to the upper portion of the second bore, a check valve in said fiuid passage to prevent back flow into the bore, said housing having a discharge chamber therein adapted to be connected to an engine, said housing having a passage therein connecting the third bore to the discharge chamber, said first bore being in communication with said chamber, and a check valve in said first bore for preventing back flow from the chamber into the bore.

6. In a fuel injection pump as claimed in claim 5, a fluid passageway connecting the upper portion of the second bore to the first bore and opening into the first bore between the suction opening and the second bore, and a passageway connecting the top of the pilot plunger to an intermediate portion thereof adapted to register with said fiuid passageway.

'7. In a fuel injection pump as claimed in claim 5, means for varying the effective stroke of the main plunger from zero to a predetermined maximum.

8. In a fuel injection pump, a housing having first and second bores of materially different displacements, plungers reciprocably mounted in said bores, said housing having suction passageways therein opening into said bores for deliver ing oil to the bores, said housing having a discharge passageway therein common to both of said bores for the discharge of oil from the bores. one of said plungers being formed of adjustably said bores, said housing having suction passageways therein opening into said bores for deliver-.

ingoil to the bores, said housing having a discharge passageway therein common to both of said bores for the discharge of oil from the bores, one of said plungers comprising adjustably connected sections adjustable relative to each other to vary the length of the plunger for varying the quantity discharge of the plunger.

10. In a fuel injection pump, a housing having therein first and second coaxial bores, said second bore being of larger diameter than said first bore, a pilot plunger in the first bore, a main plunger in the second bore, said housing having suction passages therein opening through suction openings into each of said bores, the suction opening in the first bore being closer to the effective top of the pilot plunger than the suction opening in the second hole is to the effective top of the'main plunger, means for moving the plungers at such a rate that the pilot plunger blocks its suction opening before the main plunger blocks its suction port and thus discharges first, said pilot plunger being formed of two adjustably connected sections which may be adjusted relative to each other to vary the discharge capacity of the pilot plunger.

11. In a fuel injection pump, a pump body having a large cylinder bore and a small cylinder bore in approximate alignment therewith, each bore provided with a discharge passage, said pump body having a discharge passage therein to which said cylinder bore discharge passages connect, a large plunger in said large cylinder bore, a small plunger in said small cylinder bore, said body provided with passages for delivering fuel to said small cylinder bore, and with other passages for delivering fuel to the large cylinder bore, said passages arranged whereby upon reciprocation of the plungers said small plunger will discharge a predetermined quantity of fuel through said discharge passage prior to discharge of fuel by said large plunger, said small plunger being formed of two adjustably connected sections which may be adjusted relative to each the other of said plungers, separate valve means for controlling the delivery of each of said plungers and its respective cylinder, a fuel delivery line communicating with each of said valve means and adapted to deliver fuel from both of said cylinders to a combustion chamber, one of said plungers and its respective cylinder being capable of effecting a portion of its injection at a time difierent than the time of injection effected by the other of said plungers and its respective cylinder, one of said plungers being formed of a plurality of adjustably connected sections which sections may be adjusted relative to each other to vary the discharge capacity of the plunger.

GEORGE STEVEN. ROY R. FRUEHAUF.

REFERENCES CITED Number Number 10 UNITED STATES PATENTS Name Date Gathmann Jan. 25, 1910 Daimler et a1 Jan. 14, 1913 Deschamps Nov. 12, 1935 Gambrell Dec. 6, 1938 Bischof Sept. 19, 1939 Davis Apr. 15, 1941 Links et a1. Sept. 22, 1942 FOREIGN PATENTS Country Date Switzerland 1943

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