US2458377A - Light fuel injector - Google Patents

Description

Jan. 4, 1949.

W. E. HENNINGS LIGHT FUEL INJEc'roR Filed June 3. 1944 INVENTOR MZWL EWI/#6s BY c n l t ATTRN YS Patented Jan. 4, 1949 UNITED STATES PATENT -OFFICE:

This invention relates to fuel injectors for iny ternal combustion engines, Aof the type in which fuel is delivered under pressure to the combustion chamber of the engine.

One diiliculty encountered in commonly used injectors and injector systems is the pollution of the lubricating oil in the base of the Vinjection pump by the non-lubricating light fuel which, under compression leaks pa'st the plungers of the injection pump, and, in some cases, the similar pollution of the lubricating oil in the base of the engine.

Among the objects of my invention are the overcoming of the above mentioned difficulties, and the securing of proper lubrication of the injector parts in a simple and reliable manner.

Other objects include an improved control Uof the injector and its operation and the details and arrangement of the parts, all of which will be made apparent in the following specification and claims.

In accomplishing the objects of the invention, I depart from the conventional constructions of the injector itself and the manner of its operation.

In the accompanying drawing which illustrates one embodiment of my invention,

Fig. 1 is a partly diagrammatic view, with parts in section, showing the general`arrange-- ment oi the parts and elements in relation to an engine cylinder and to each other;

Fig. 2 is a longitudinal sectional view on a larger scale, of an iniector, illustratively embodying certain features of the invention; and

Fig. 3 is a detail view, on a smaller scale of the high pressure injector control pump, looking from the l'eft in Fig. l.

Referring to Fig. 1, the fuel injectorfsystem is shown as generally comprising the fuel injector I 0, mounted in the head ofan engine cylinder Ii, a fuel tank I2, connected by a feed line I3 to a fuel transfer pump unit which includes. a lter i4 and diaphragm pump I5 of conventional design. The pump I5 connects by fuel line I6 to the injector l0. An oil supply tank is shown at i1 from which an oil supply line I8 leads to a low pressure pump I9 which supplies a high pressure pump 2G through a line 2l. Surplus oil supplied to pump 20 by pump I 9, is returned to tank l1,-

through a check valve 22 and line 23. A power line 24 connects the pump 2li to the injector I0.

Referring to Fig. 2 the injector I0 is shown as comprising a body member 25 formed with a cylindrical bore 26. Member 25 is provided at its lower end with an extension 21 of smaller diams claims. '(cl. 1ozmi eter through which a passage 2l opens to a recess or chamber 23. The upper end of member 25 is closed by a cap 30 threaded into the upper end of bore 26. Cap 3B is provided with a recess 3l in which is threaded a coupling member 32. Member 32 is formed with a passage 33 opening to a chamber 34 formed in member 32. Chamber 34 houses a check valve comprising a ball 35 held in position to close the inner end of passage 33 by a four prong spring 36. Passages 31, 38, 33 and 40 formed in cap 30 and member 25 connects chamber 34 with the bottom of bore 26. A movable wall member divides bore 26 into two chambers. As shown this member comprises a piston member 4I lap fitted to slidey in the cylinder 26 and forming with the cylinder a fuel 'chamber 42 below the piston. The piston 4I is recessed at its upper end to form a iiuid pressure chamber 43. A spring 44 positionedI in the form illustrated, in chamber 42, presses the piston 4| toward its upper position, as shown in Fig. 2. A passage 45 opens from chamber 43 through cap 30 and a coupling member 46 which may be formed integral with the cap.

An injection. nozzle 41 provided with an atomizing jet discharge opening 48, is threaded on extension 21. The nozzle 41 is formed with an -annular shoulder 49 which supports a four-prong spring 50 acting to press ball 5I into position to close passage 28 and form a spring loaded discharge valve between chamber 42 and the discharge opening 48. The nozzle 4l is exteriorly threaded at 5,3 for connecting the injector unit to the engine cylinder as shown in Fig. 2. As shown in the latter ligure fuel line I6 is connected by a conventional coupling 54 to the coupling member 32 of the injector and pressure line 24 is connected by a similar coupling 55 to coupling member 46.

The piston il of the injector is operated by pump 2U, as later more fully described by oil ofa lubricating Quality supplied under pressure to the chamber 43 through pump 20 and line 24 by the pump I9. Pump 2U is of the metering type. Various forms of metering pumps may be used subject tothe modication of their operation to conform to the purpose of my invention as hereinafter pointedout. As shown, one form of such pump is indicated generally. at 20 and comprises a housing 51 in the upper portion of- I pump pistons being shown at 59. The piston 59 operates in a, cylinder 50 to which ports 3j open from sump `58, when the piston is in its lowermost position, to admit oil to the cylinder 60 above the upper end of the-piston. The lower end of the piston isprovided with a shank 62 connected to'fa block. 33 having on its lower face a groove in which is mounted a cam roll 35, engaged ybyeccentric cam 63 secured to shaft B1. A spring 63. compressed between a web oi' the housing and the block 33, maintains roll will be obvius rotation of shaft 81 will effect reciprocatioi;,iiI ofthe piston 59. The piston 59 is provided [with a vertical groove 'Ill connecting its upper face. with a circumferential groove having a helical'jupper edge 12, positioned to cross the port 8i as. the piston 59 approaches or reaches the upper end of its stroke thus reducing'th'e pressure of the oil in the power line 24 to that cally opposite vertical slots I1 In which the ends of a pin lcarried by the piston. shank 62 engage. The gear I5 is rotated by a rack 'I9 which is reciprocated by any suitable means. The shank 62 is connected-to block 33 by a swivel 80, the block 63 being held against rotation in any suitable manner as by the engagement of the shaft of cam roller 65 in a groove (not shown) in the wall ofJ the pump housing. In general, the construction oi pump`20 as described follows a conventional form but for'my purposes the usual check valvein the discharge port of the pump is eliminated. Check valve22 in line 23 serves to maintain the' oil in the sump 58 at or below the pressure of pump I9.

The camshaft 61 is driven from the engine shaft through suitable timing gears, generally indicated at-3 in Fig. 3, and the several cams 85 for operating the pistons of pump 20 are positioned on shaft t1 so as to' give the desired sequence of operation to the injectors of the several'enginepcylinders.

When the system is inoperation fuel pump i! transfersfuel from the fuel tank I2 to chamber 42 of the injector. The fuel pump may be driven fromthe camshaft of the engine or from shaft 31 of ,pump 20. The lubricating oil which is used asv a hydraulic medium follows two cir' cuits. The iirst is a low pressure circuit activated' by. the low pressure pump I9. The second is a. circuit which is intermittently high and low pressure and is activated by pump 20. In the first circuit'oil is transferred by pump I9 from the reservoir I1 to the sump 58 of pump 20. From lthe sump it flows through valve 22, which controls the oil pressure in the sump, and returns to the reservoir II. It is to be noted that since the oil is always under pressure it will have no chanceto develop air bubbles which are a frequent cause of trouble in fluid pressure operated systems. Once assembled as a unit and having the air properly bled from the lines my system should develop no air bubbles. In the second circuit the oil from the sump 53 which is under pressure from pump .I9 and valve 22 will .3B in operative engagement with the cam 38. As

enter cylinder 3|! through the ports 3| when the piston 59 is in its retracted position and will ll the line 24 and chamber 43 of the injector. The pressure exerted by pump I5 on the fuel entering chamber 42 is less than the pressure of the oil in chamber 43 so that no light fuel/can pass the injector piston 4I to contaminate the oil in chamber 43. The combined pressure of the fuel and spring 44 however is greater than the pressure on the oil from pump I9 so that vl the injector piston 4I ls held in its retracted position. When the drive shaft of pump 20 advances piston 59 the latter traps the oil above the ports 6I and acting through the oil filled line 24 increases the pressure in chamber 43 to an amount greater than the combined pressure of the fuel and spring 44. The injector piston 4I' is therefore advanced against the pressure of ,the fuel and spring 44, closing check valve 3| and driving the trapped fuel in chamber 42 through the discharge valve 5I in the nozzle 41 and out through the spray jets 48 into the combustion chamber of the engine cylinder on which it is mounted. When the piston 53 of pump 20 finishes its power stroke,

' either by reaching the end of its mechanical stroke or by the metering operation of the helical edge 12, the pressure in chamber 43 falls to ,that maintained in sump 58 and the spring 44 causes the piston 4I to return to its retracted position, the oil in chamber 43 and line 24 lowing back into pump 20 as piston 59 retreats. At

. the same timethe discharge valve 5I closes under the pressure of its spring 50 and fuel under the pressure of pump I5 opens check valve 35 and rells the fuel chamber 44 of the injector. The system is then ready for another fuel injection.

i In the event that any oil has leaked past either piston 4I or piston 59 it is replaced by the operation of pump I 9 which maintains a constant supply ofoil in sump 58. Due to the fact that the pressure of spring 44 is always added to the pressure of the light fuel, the pressure of the lubricating oil can always be greater than the pressure of the light fuel so that in my system the piston -of the injector may be lubricated by the lubricating oil from the uid pressure operating system and any leakage which can take place is of lubricating oil into the fuel which is the reverse of present systems.

Furthermore my system andthe structure of the injector makes possible an improved flexibility of adjustments. The duration of the power stroke and therefore the duration of the fuel injection may be adjusted by adjustment of the metering element of the uid pressure pump without recourse to the operating parts of the injector itself, and the pressure differentialsy in the system may be adjusted by varying the pressure exerted by spring 44 and the spring 85 of. valve 22, either by the use of shims under the springs or by sub-` stituting springs of differentstrength. The action of springs 36 and 50 may be similarly adjusted.

I claim: A 1. Fuel injection apparatus for internal combustlon engines which comprises, a fuel injector having a moveable wall member, a fuel chamber at one side of said member for receiving" fuel under pressure and a fluid pressure chamber at the opposite side thereof, a discharge opening from the fuel chamber, al spring` loaded discharge valve closing said opening, a spring acting against the piston in the samedirection as does the fuel pressure, an independent oil supply for said fluid pressure chamber, pump means for maintaining the supply of oil to the .fluid pressure chamber and for maintaining the oil pressure in said chamber above the pressure of the fuel but less than the combined pressures of the fuel and the spring and a second pump acting on the oil supplied to the fluid pressure chamber to intermittently increase the pressure of the oil above the combined pressures of the fuel and the spring.

2. Fuel injection apparatus for internal com-" bustion engines which comprises. a fuel injector having a piston,a fuel chamber at one side of the piston for receiving fuel under pressure and a fluid pressure chamber at the opposite side thereof. a discharge opening from the fuel chamber,

1 a spring loaded discharge valve closing said opening, a spring acting against the piston in the same direction as does the fuel pressure, an independent oil supply for said duid pressure chamber, pump means for maintaining the supply of oil to the uid pressure chamber and for maintaining the oil pressure in said chamber above the pressure of the fuel but less than the combined pressure of the fuel andfspring and a second pump acting on the oil supplied to the fluid pressure chamber to intermittently increase the pressure of the oil above the combined pressures of the fuel and the spring.

3. Fuel injection apparatus for internal combustion engines which comprises, a fuel injector having a piston, a fuel chamber at one side of the piston for receiving fuel under pressure and a uuid pressure chamber at the opposite sidethereof. `a discharge opening from the fuel chamber. a spring loaded discharge valve closing said opening, a spring acting against the piston in the sauleA combined pressures of the fuel and spring, and e.y

variable discharge metering pump acting on the oil in said sump to intermittently increase the pressure in said line and the fluid pressure chamber above the combined pressures of the fuel and 4. Fuel iniection apparatus for internal combustion engines which comprises, a fuel injector having agpiston, fuel chamber at one side of the piston for recel fuel under pressure and a iluid pressure chamber at the opposite side thereof, a discharge opening from the fuel chamber, a spring loaded discharge valve closing said opening, a spring acting against .the piston in the same direction as does the fuel pressure, an independent oil supply for said uuid pressure chamber including a sump, an oil line connecting said sump and iiuid pressure chamber, a pump supplyin! oil to the sump, a spring loaded overflow check lvalve in the sumpfor maintaining oil in the sump, line and fluid pressure chamber and at a predetermined pressure greater than the fuel pressure but less than the combined pressures of the fuel and spring, and a metering pump acting on the oil in the sump to intermittently increase the pressure in said line and the fluid pressure chamber above the combined pressures of the fuel and spring.

5. Fuel injection apparatus for internal com bustion engines which comprises, a fuel injector having a piston, a fuel chamber at one side of the piston for receiving fuel under pressure and a fluid pressure chamber at the opposite side thereof, a discharge opening from the fuel chamber, a spring 'loaded discharge valve closing said opening, a spring acting against the piston in the same direction as does the fuel pressure, an independent oil supply for said fluid pressure chamber including a metering pump having an unchecked opening to the cylinder of the metering pump,

an unchecked discharge line connecting the cylin-` v der of the metering pump to the fluid pressure chamber, a pump supplying oil to the sump, a spring loaded overflow check valve in the sump for maintaining the oil in the sump, metering pump cylinder, said discharge line and fluid pressure chamber `at a predetermined pressure greater than the fuel pressure but less than the combined pressures of the fuel and said spring, means for intermittently advancing the piston of the metering pump past the opening from the sump to the cylinder of the metering pump to trap the oil in the discharge line and fluid pressure chamber between the piston of the metering pump andthe piston of the injector to increase the pressure of the trapped oil to an lamount in excess of the combined pressure of the fuel and said spring.

WILLIAM EARL HENNINGS.

REFERENCES CITED The following -references are of record in the file of this patent:

UNITED STATES PATENTS A Name Date Dussmann Mar. 6, 1934 Hermann Apr. 17, 1934 Koster et al. Mar. 10, 1936 Bischof Sept. 19, 1937 Outin Apr. 28, 1942 Heuser et al. Nov. 10, 1942 Dodson Mar. 14, 1944 maman PATENTS Number Number Germany .v-'.. --1934 Germany an. 16, 1937

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