US2265692A - Fuel injection system for internal combustion engines - Google Patents

Description

Dec. 9, 1941.

G. S. KAMMER FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES 4 Sheets-Sheet 1 Filed June 5, 1940 9, 1941. AMM R 2,265,692

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 5, 1940 4 Sheets-Sheet 2 Dec. 9, 1941. G. s. KAMMER FUEL INJECTION SYSTEM FOR INTERNAL'COMBUSTION ENGINES Filed June 5, 1940 4 Sheets-Sheet 3 Dec. 9, 1941. 2,265,692

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES G. S. KAMMER Filed June 5, 1940 4 Sheets-Sheet 4 Patented Dec. 9, 1941 FUEL INJECTION SYSTEM FOR mum Y Y COMBUSTION ENGINES George Stephen Kammer, High Anstby, Middleton, near Ilkley, England Application The invention relates to fuel injection systemsfor internal combustion engines.

It is an object of the invention to provide entirely hydraulic actuation of the injection valves, utilising the fuel itself ashydraulic pressure medium.

It is a further object of the invention to adjust the'oil pressure in an accumulator for such valves by automatic means in dependence on the speed of the engine.

Another object of the invention is to provide in a hydraulic accumulator automatic unloading means for the pump supplying the accumulator such that the unloading pressure can be varied.

A further object of.the invention is to cause the injection nozzles of the engine to open on a drop in hydraulic pressure in a control line thereto and to close again on restoration of the pressure. 9

Yet another object of the invention is to provide hydraulic control means for the nozzle valves permitting them to remain open for very short periods, such as 1 to 2 of crank angle.

A- still further object of the inventionis to provide a double seated valve for the said hydraulic control operable by resilient means at predetermined times to drive the valve member on to one seat, the member automatically rev turning to its other'seat under the effect of the hydraulic pressure Another object '30 to provide two" or more sets of orifices .in the nozzle and to control the supply of fuel thereto in such a manner as-to produce a desired stratification of the charge varying in dependence on the engine speed! With these and other objects in view the invention will be explained in further detail by I means of the accompanying drawings, in which line V-V,

' Figure6 is a partial section through an alternative form of distributor,

' Figure? is a section through one of the resilient cams for the same,

Figure 8 isa perspective view of one .of the cam' members,

'inder of the engine. connection of theline 5 to the nozzle valves of June 5, 1940, Serial No. 338,998 Germany March 10, 1939 5 Claims. Cl. 103-41) Figure 9 is a sectional elevation of theinjection nozzle and valves.

Figure 10 is a portion of Figure 9 on an enlarged scale to show the nozzle and valve construction, H

Figure 11 is a developed" view of a part of the cap nut securing the washers to the injector body to show the shape of the orifices,

' Figure 12 is a section of Figure 10 on the line XII-XII,

Figures 13 to 18 inclusive are diagrams of different cam shapes and corresponding injection curves, and

Figure 19 is a view corresponding to Figure 10 or a modifiedform of nozzle valve.

Referring first to Figure 1, a hydraulic pump and accumulator are combined in one casing 43. The pump is driven from the lay shaft-42 and is supplied with liquid fuel by. the inlet line 45. The accumulator pressure is varied by the action of a governor 46; shown conventionally as of the flyball'type, On a shaft 41 as will be subsequently explained in detail, and the fuel under pressure is discharged through the line 5 to a distributor valve 49, of which one is provided for'each cyl- Thearrow indicates the other cylinders. The nozzle valve is also connected by a control line I to the distributor 48.

' The function of the distributor is to drop the.

' pressure in the line 1 when fuel-injection is to emdr is duplicated to show" the control of start and to restore the pressure to terminate the injection period. The distributor is driven by the lay shaft", which is duplicated in the figure for the sake of clarity. Similarly the govinjection times to and loads.

The foregoing paragraphs set out in broad suit different engine speeds outline the cooperation of'the various parts of the fuel injection system according .to the invention. They will'facilitate arr-understanding of the more detailed description now to be given of the various parts of which the system is composed.

The pump and accumulator are-shown in Figure 2. Here the lay shaft 42, positively driven in the usual manner from the engine shaft by means not shown, is mounted inthe casing 43. The shaft 42 carries an eccentric 50, against which the pump plunger 5| is pressed by a spring 52. The pump cylinder 53 has ports 54 for the inlet of fuel fed from the passage 55 connected The line5 is also branched to feed a nozzleto the inlet line 45. The pump delivers the fuel through a spring loaded nomreturn valve 56 and a passage 51 to the accumulator space 58.

The accumulator comprises a plunger 59 urged upwards by a spring 60. A groove 6| with oblique edge is provided in the plunger 59 to register with passages 62 and 63 when the accumulator reaches the desired pressure. The passage 62 communicates with the pump pressure space 64 and the passage 63 through the return system of pipes ll) shown in Figure 1 with the fuel inlet passage 55, so that when the hydraulic pressure but not with undue rigidity.

accumulator plunger 59 has reached a positioni corresponding to the desired pressure, the fuel delivered by the pump plunger 5| passes through the passage 62, the groove 6|, the passage 63 and the line l back to the inlet passage 55.

The shaft 41 is provided with a worm to engage teeth 65 on the plunger 59. The shaft 41 can be rotated in either direction to turn the plunger 53;,'and so bring the port terminating the passage 62 into register with a narrower or wider part of the groove 6|. position of the plunger at which unloading of the pump takes place and accordingly also the accumulator pressure maintained. The shaft 41 is actuated by the governor 46 as indicated in Figure 1.

The fuel is delivered through the line to the distributor 48 and to the nozzle valves 49. A preferred form of distributor as shown in Figure 1 at 48 will now be described.

Referring'to Figures 3, 4 and 5, the lay shaft 42 duplicated at the right hand side of Figure 1, has a cam disc 3| mounted upon it. The cam disc 3| has a raised portion 32 tapered in the axial direction to vary the timing by axial movement of the disc. A torsion bar 33 is journaled in the distributor casing 34 and has a lateral arm 35 which is adapted to be lifted by the raised portion 32 of the cam disc 3| passing under it. Near the other end of the rod 33 there is another lateralarm 36 projecting in the opposite direction to the arm 35. The arm 36 is in such a position that a twist of the bar 33 will depress a control valve member 31 by the action of the arm on the stem 38 of the valve.

A piece 39 screwed into-the casing 34 consti tutes an upper seating for the valve and permits communication past the stem 38 of the valve to the space below the valve when the latter is pressed by the arm 36 off its upper seating. The line 5 from the accumulator pressure space 58 (Figure 2) communicates pressure through a port 4| in the lower seating of the valve to the space above when the valve is lifted. The space between the valve seats is in communication as shown with the control line 1 for the nozzle control valve 49 (Figure 1).. The total movement of the valve member 31 may be of the order of .01"

or less.

' In operation the cam disc 3| is rotated by "'the lay shaft 42 at. the appropriate speed, that is at the same speed as the-crankshaft in two-stroke engines or at half that speed in four-stroke enines. Oil under pressure is admitted through the line 5 and port 4|, holding the valve 31 against its upper seat 39. The oil pressure is thus communicated by the connection 1 tov the nozzle control valve 49, keeping it normally closed.

When the raised part 32 of'tlie disc 3| comes under the arm 35, the latter is lifted and the bar 33 is rotated a little, moving the arm 36 downwards. The arm 36 presses on the stem 38 of the valve member'31 and pushes the valve member In the position now assumed by the valve the pressure supply from the line 5 is cut off from the control line 1, and this line is put into 'communication with the space inside the casing 34. The seepage of oil returning through the liner1 due to the relief of pressure is discharged from the space 44 by the return lead ID, of which the end is indicated in Figure 3, to the fuel supplY..

This adjustment varies the v the lay shaft 42, so that one raised part 32 actuates the different valves 31 in correct sequence. The line 5 is branched to the different valves, and similarly the line H1 is branched to the several casings 34. The lines 1 are'kept separate,

each one leading to its associated nozzle control vvalve.

Figure 4 shows another valve 31 and its associated parts at from the one described in detail, while Figure 5 shows the four operating rods 33 for a four cylinder engine.

It will be noted that in the distributor construction disclosed there are no closely fitted parts or members liable to seizure or breakage ,nor are there any springs.

The construction is simple and cheap,'even including the grinding and fitting of the 'valve member and seatings, which involve no special features.

It may be found desirable however in some cases to use a spring in place of the torsion bar, and this is shown in Figures 6, 7 and 8, which will now be described.

Figure 6 shows two valves and cams, but onlv one will be described at first. The valve itself and its connections are as already described in connection with Figure 3, the valve being held normally on its lower seating by the oil pressure in the line 5. The valve stem 38 projects through a gland l8, .so that the valve can be pressed on to its upper seating by pressure applied to the stem 38.

A resilient cam 20 can pass under the valve stem 38 and lift the valve 31 through the intermediary of a ball 22, driving the valve on to its .upper seating and depriving the line 1 of oil pressure, which then passes away through the lead I 0 as before.

The resilient cam 20 is housed in a drum 26, which can be slid axially by means of the governor 46 of Figure 1, in which the connection is indicated conventionally as a bell crank lever.

" ther washer.

cam 20 passes under the stem 38, the valve will be raised, and when already on its upper seating, the spring 21 will be compressed. Pressure is thus released from the line 1 just as in the case of the distributor of Figure 3.

Figure 9 shows a cross-section of a twin needle injection valve 49 in place in Parts of the cylinder body as shown at 23, 23 and of the cylinder head at 24, while 25 denotes the crown of the piston at it upper dead centre position. In

2. The hollow pistons 3 are each located in a bore 4 coaxial with the respective needle valve and are of larger diameter than the needle valves themselves. The fuel-feed line 5 is connected to the space 6 around both needles, so that this space is held under constant fuel pressure tending to open the needle valves I by differential hydraulic action. To keep the valves in the closed position fuel is admitted from the distributor 48 to the bores 4 by the lines 1. Seepage fuel leaves the injector by a channel 8 connected to the spaces 9 and is taken back to the fuel supply by the line I0.

The actual nozzle is better seen in Figure 10. Therein only one needle valv I is shown, which has its seating in the injector body 2. The needle is shown in the closed position. Fuel enters through line 5 into space 6. When the needle valve is lifted, the fuel can also enter the bore II and consequently the grooves I2 and the 011".- cular groove I2a above or in the washer I3. The washer I3 and also the lower surface of the injector body 2 are machined flat, andthe washerv I3 has an annular recess I4 coacting with the grooves I2. A further washer I5 abuts against the washer I3 and also has an annular recess I1.

Of course more washers may follow. The washer I5 is conical near its edge in the form shown, but of course it maybe plane, ifnecessary.

The washers are secured and pressed together and against the injector body 2 by means of a cap nut I6. Figure 11 shows part of the cap nut I6 as a developed views of its cylindrical surface, having orifices at the level where the washers join, exposing annular recesses between them.

washers, the oil under pressure entering the grooves I2 and I2a and the recesses I4 and I1 Figure 12 shows the arrangement of thethe cylinder. 5

the injection valve two nozzle needle valves I are incorporated in the injector body 20 engage the corresponding control valves 31 of the different cylinders in succession and raise them. -Thus each time a valve 31 is lifted the pressure fuel entering it through the lead 5 will be cut off and the pressure in the line 1 connected to the corresponding needle valve Piston 3 will drop to the pressure prevailing in the return line III, and so the needle valve I to which that particular lead 1 is connected will be raised by means of hydraulic pressure on the conical part of the needle valve; I Thereupon the fuel oil under pressure in lead 5 and space 5 will enter the bore II, the grooves and the recess I4 or I1 and will be pressed out along the portions of the recess I4 or I1 registering with the orifices in the cap nut Hi. This gives a ribbon-shaped fuel spray, and'a's the depth of th recess can be made extremely small, the gap will produce an extremely fine fuel spray.

When thecam 20 passes the ball 22, the spring 21 will again expand and the valve 31 be pressed interruption of the fuel supply into the cylinder through the orifices in question.

Although the needles of one injector may be operated simultaneously, advantageous effects are secured by choosing the shape of the cams 20 for diiferent timing. In this 'way. many variations of timing can be obtained. It is possible to alter the gap between the'washers, that is the thickness of the spray-ribbon, and both the number and the diameter of the orifices in the cap nut. Thus for example one set might only have 3 orifices of in. diameter, and the other set I2 of say ,4 in. diameter, and'while the gap 1 height of the former set may be of the order If the cap nut is made to fit tightly around theof in. the gap of the latter may be $5 in.

With the depth and the height of the gap and the diameter of the orifices it is, within certain limits, possible to vary the penetration of the fuel particles. The penetration also depends on the pressure of the I cylinder. j This variation can advantageously be used to stratify the charge or to produce locally an over-fat mixture in the following manner.

Suppose the sparking? plug of. a gasolineinjec tion engine is located peripherally in the cylinder I head, or two such-plugs are located opposite each grooves and oil leads inthe case of two washers, f

each recess I4 and I1 being fed'through a duct I I from-its associated needle valve independently of the other.

Reverting to Figure 6, a second cam valve 31 are shown. The two valves 31 are connected through separate control lines 1. to the 20 and two needle valves of Figure 9, so that the timing I of injection may be made different for the .two

sets of orifices and I1. Ofcourse a third valve with cam and needle valve could be added, and so on, the extra orifices being provided by a furdrums' 25 as in the case of the distributor of Figure3. r

- The distributor drum 26 is rotated at a speed The valves 31 for the other cylinders are appropriately spaced around thecam suitable .for, the: engine in question, that isat' crankshaft speed in two-stroke engines, and half this speed in four-stroke engines, and the .cams

other and peripherally, while the injector is located in the centre of the cylinder. Let the injection start at a very early stage of the compression stroke, out of few orifices directed on its inward stroke.

wards the piston, which'is During the long injection period out of these few orfices coacting with the lower washer a fairly evenly distributed weak mixture is produced in the cylinder. Very shortly before the spark has I: ignite, injection outof the second, or upper set of orifices, will start and he performed rapidly to full quantity, while the orifices may be directed toward the sparking plugs,- or elsewhere, where they will crease an overrich orgoverfat mixture.

Another example of stratifying the charge is for use in compression-ignitionengines. Let-the orifices of the lower washer-be distributedevenly H over th'eperiphery and be of; very small crosssection, or they may be of moderate-diameter. I and the gap" be extremely line; A verypsmall quantity of fuel-will be evenly distributed-in the fuel and the pressure in the combustion space and form an extremely closes after the otherset at loads about three-quarters,- 1 Of course, all sorts of, other combinations including more than two cams and sets of orifices weak mixture.

, Once this has been self-ignited, the second set of orifices may come into operation and inject the bulk of the fuel tolbe consumed in a com-" paratively short time, 'I-here may then be a third set of orifices, injecting" fuel after the bulk of combustible has already been fed into the combustion space.

It will be seen that by this methodit is possible to vary the amount or fuel fed into the, cylinder and thus exert a very close control over the process of pressure rise without losing valuable oxygen merely because the fuel molecules cannot be seized by one single set of injection orifices and at one single speed of fuel supply, whereas the amount of excess air would allow more fuel to be burnt without excessive temperature rise.

Further, there is no compromise in the best speed of injection at various instants due to limitation in pressure rise, as the rate of fuel feed can be made to vary as desired during the period of injection.

. Figures 13 to 18 show different shapes of cams for operating two injector needle-valves, with corresponding'curves of opening times in crank angle of the two sets of orifices plotted against the setting of the cam drum 20 along the lay shaft 42 to show the simultaneous rates of fuel feed through the two sets of orifices.

Figure 13 is a diagram in which the abscissae represent diflerent settings of the cam drum 26 along its driving shaft to suit diflerent loads. The settings are-carried out by the governor 46 of Figure 1. The ordinates represent time as measured by crank angle. Figure 14 is a development of the two cams showing their location relative to the balls 22 with injection cut right on. As the cam drum is moved to the left the time of injection passes from A'to B and gradually increases for one set of orifices, while the other set, remains closed. As the cam drum 26 is moved further along the shaft corresponding to the horizontal line BC, the time of injection remains constant, but the second set of orifices comes into operation as represented by the hatched triangle EFG, injecting a continuously increasing quantity of fuel. The line FG is entirely within the line CD, which means that j, the time of injection is not increased by the coming into operation of the second set of orifices but only the rate of feed. -The second set may i be regarded as providing the main supply of fuel, while the first set provides pre-injection and postinjection, but all within a constant period of time measured as crank angle. At high loads the bulk of the fuel is fed in in a comparatively short 7 time and at low loads the quantity of feed can be accurately adjusted by the governor to the operating-conditions.

1 Figure 15 is a diagram similar'Figure 13,. 1 but with the difference that at heavy loads the second set of orifices continues injecting after the first. The cor-responding cams are shown in Figure 16.

Figures 17 and 18 similarly show another timing arrangement in which the first set of orifices opens at a constant time and closes progressive-' 1y later up to three-quarter load, and the second set, providing the bulk injection, opens progressively earlier at small loads from no load and greater than can be made according to requirements. In many instances it "will be advantageous to determine the best combination by experiments on the actual engine.

It may sometimes be found convenient to adopt the alternative form of nozzle shown in Figure 19. This shows two needle valves i in the injector body 2 with the lead 5 to convey fuel at constant pressure to the space 6 around the needle ends.

The operating mechanism for the needle valves is not shown, since it is the same as .shown in Figure 9.

The nozzle body I9 is in a single piece and is clamped against the injector body by.the cap nut l6. One needle valve when open admits fuel to a passage 2| terminating at the centre of the face and registering with a passage 29 drilled on the axis of the nozzle body I, which terminates a little short of its outer extremity and communicates with orifices 66 drilled to direct the fuel in the desired direction.

The other needle valve communicates with a passage 36, which registers with an annular. groove 40 in the upper face of the nozzle body, I

from which oblique passages 6'! feed the fuel to orifices 68. The orifices 66 and 68 are arranged in separate rings on a conical'projection 69 of the nozzle body. A gasket 10 between the in-.

jector body and the nozzle body prevents leakage between the passages but may be omitted if desired.

The modification last described is intended more particularly for cases in which a jet of greater penetrating power is required than can be provided by the nozzle arrangement shown in Figures 9 to 12. I v

It can be seen from the foregoing description that the invention permits a hitherto unknown fineness of control of the pressure and temperature cycles of an engine, and the the excess air quantity in compression'ignition engines can be reduced without damage to the engine, so that the output can be raised and the specific consumption slightly improved.

What I claim is:

1. In a fuel injection arrangement for an internal combustion engine, a charging pump having suction and delivery spaces, a hydraulic accumulator constituted by a plunger movable axl ally in a pressure space androtatabl'e on its axis and resilient means pressing on the plunger, a

feed connection including a non-retum valve between the pump deliver space and the accumulator pressure space an oblique edged groove on' feed connection including a non-return valve bea tween the pump delivery space and the accumulator pressure space, said accumulator plunger having a groove located to establish connection between the delivery and suction spaces-of the pump when the resilient means has been compressed by a predetermined amount, said groove at a portion thereof progressively varying in cross sectional area in a direction about the lon'- gitudinal axis thereof, and means for rotating the plunger to vary the pressure at which the groove establishes the said connection. I

3. In a fuel injection arrangement for an internal combustion engine, a charging pump having suction and delivery spaces, a hydraulic accumulator constituted by a plunger movable axially in a pressure space and rotatable on its axis and resilient means pressing on the plunger, a

feed connection including a non-return valve be-l tween the pump delivery space and the accumulator pressure space, an oblique edged groove on the plunger being located to establish connection between the delivery and suction spaces of the pump when the resilient means ha been compressed bya predetermined amount, and means for rotating the plunger to vary the pressure atv which the groove establishes the said connection.

4. In a fuel injectionarrangement for an internal combustion engine, a charging pump having suction and delivery spaces, a hydraulic accumulator constituted by a plunger movable axially in a pressure space and rotatable on its axis, and resilient means-pressing on the plunger, a feed connection including a non-return valve between the pump delivery space and the accumulator pressure space, an oblique edged grooveon the plunger being located to establish connection between the delivery andsuction spaces of the pump when the resilient means has been compressed by a predetermined amount, axially elongated teeth on the plunger, a worm in engagement with the said teeth, and mean for rotating the worm to vary the position of the plunger at which the groove establishes connection between the delivery and suction spaces of the pump.

5. In a fuel injection arrangement for an internal combustion engine, a charging pump hav-

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