|Publication number||US2984230 A|
|Publication date||May 16, 1961|
|Filing date||Jul 29, 1957|
|Priority date||Jul 29, 1957|
|Publication number||US 2984230 A, US 2984230A, US-A-2984230, US2984230 A, US2984230A|
|Inventors||Clessie L Cummins|
|Original Assignee||Clessie L Cummins|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (13), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
May 16, 1961 c. CUMMINS FUEL INJECTION SYSTEM 3 Sheets-Sheet 1 Filed July 29, 1957 mvemon CLESSIE pcuumms 'ALSTORNEYZ Q L i HH U y 16, 1961 c. L. CUMMINS 2,984,230
FUEL INJECTION SYSTEM Filed July 29, 1957 3 Sheets-Sheet 2 INVEN TOR CLESSIE L. CUMMINS llll'l United States Patent FUEL INJECTION SYSTEM Clessie L. Cummins, 80 Cloudview Road, Sausalito, Calif.
Filed July 29, 1957, Ser. No. 674,702
4 Claims. (Cl. 123-140) My invention relates to improvements in the fuel injection systems of compression ignition internal combustion engines and injectors therefor. The invention also lends additional value and usefulness to the fuel supply apparatus shown in my Patent No. 2,670,725 and can be incorporated with the braking apparatus shown in my copending application S.N. 662,494 filed May 29, 1957, now abandoned.
For a long time, one of the serious problems facing the compression ignition engine industry has been to discover a fuel injection mechanism that would require an absolute minimum of servicing, that would have a long life, that would be simple, and that would require no special attention being paid, at the time of installation, to the fuel piping to and from the engine. This last requirement, as well as others enumerated, is met by the present invention.
The critical balance of pressures required by existing systems in controlling proper values of the several metering points in the fuel injection system in order to deliver the proper amount of fuel into the combustion chamber has been and continues a major problem. By means of by invention it is now possible for an engine manufacturer to ship an engine to a user, adjusted on a dynamometer at the factory to deliver the required horsepower, and for the installer to install the engine without further calibration, and without the necessity of periodically recalibrating the fuel system. Also by my invention the installer in connecting the engine to the fuel source, is no longer required to provide return line piping of special size, with each bend and restriction critical to the operation of the engines fuel system.
It is, therefore, one object of my invention to make the installation and operation of compression ignition engines independent of a fuel return line; or of having to maintain balanced pressures if a return line is used; or of the hazards that at present are known to exist where a balance of pressures is relied on in regulating the fuel fed to the engine.
An object of the present invention is, therefore, to pro vide a structure by which the fuel and air are so thoroughly mixed and heated that upon injection into the combustion chamber the burning of the fuel mixture will begin without delay.
Another problem having to do with the Cummins type injection engine arises from the physical wear and tear on the injection mechanism where some or all of the fuel remains in solid form at the time of injection. This is due to imperfect preparation and mixing of the air and fuel in the plunger chamber.
An object of the present invention is therefore to provide a novel form of injector mechanism which cooperates with the compressed air forced into the plunger chamber from the cylinder to produce two impinging streams which effect an even distribution and mixing of fuel and air throughout the plunger chamber.
I have discovered that other problems heretofore existing in fuel injection systems are solved by making each Patented May 16, 1961 ice injection device with the fuel supply port arranged in the wall of the injector housing bore so that the port is never uncovered upon the retraction stroke of the injector plunger, but instead is indexed with a cross port in the plunger. This location of the fuel supply port leads to another advantage in that it requires a fuel passageway from the cross port down through the injector plunger. This passageway may take the form of an axial bore ex-. tending from somewhere on the tip of the injector, upwardly to the cross port, the latter being adapted to indexwith the fuel supply port in the Wall of the injector housing bore. This conducts relatively cool fuel down through the plunger body so the plunger is cooled evenly. This even cooling means less tendency for the plunger to warp or swell. Also it delivers the fuel at or near the center of the plunger chamber in the injector housing so. that the hot compressed air coming into this chamber through the spray orifices will impinge with it and will mix more evenly. This has a very beneficial effect in preparing the fuel mixture, because it appears to release the more volatile fractions in the fuel as it is mixed with the hot air.
Another advantage of my fuel injection mechanism is that it places the working areas of the plunger cross port and of the fuel supply port up away from the working end of the plunger and in the area where more accuracy in dimensions can be maintained. It is a well known fact that a bore tends to bellmouth at its ends and a plunger tends to be slightly under-size at its end.
Another problem with one current form of injector device, which has the fuel inlet port positioned in the plunger chamber, is that the hot gases coming up into the plunger chamber from the combustion chamber will leak past the end of the plunger into the fuel inlet port. There these hot gases will tend to dry out the fuel and to leave a carbon deposit on the walls of the fuel conduit. This affects engine performance so seriously that it is necessary periodically to clean outthis carbon deposit. One object of the present invention is to eliminate this problem.
Another important advantage of my invention over prior devices is that the fuel supply port in the injector housing and the cross port in the injector plunger are both located where the housing can be of sufficient thickness so that it will not change shape during assembly or use A further advantage of my new fuel injector construction is that it lends itself to a fuel system in which the injector plunger can be immobilized when the vehicle in which the engine is installed is coasting, and during this coasting period fuel can be circulated around the plunger to cool it and to carry away any air bubbles which may be blown up from the combustion chamber through the plunger chamber.
Other objects and advantages of my invention will be come apparent from the following description and the accompanying drawings in which:
Fig. 1 is a schematic diagrammatic view of one form of my improved fuel and injector system showing the piping and the control circuits;
Fig. 2 is a view in cross section of a modified form of injector mechanism having provision for the circulation of fuel when the engine is being motored, as when coast- Fig. 3 is a view in cross section of the tip end of the injector of Fig. 2 showing a modified form of plunger tip and one having fewer lubrication channels;
Fig. 4 is like Fig. 3 with the extra lubrication channels omitted;
Fig. 5 is a view in cross section of the tip end of an injector with the plunger having a check valve in the fuel passageway;
Fig. 6 is an enlarged fragmental view of the check valve in Fig. 5 r
Figs. 7 and 8 are views like Figs. and. 6 respectively showing another form of check valve;
' Fig. 9 is a diagrammatic view showing a modified form of cam to achieve a two-stage operation of the plunger; Fig. 10 is an enlarged diagrammatic view showing the impinging streams of hot gas and fuel in the plunger chamber;
Fig. 11 is an alternative form of switch actuator for the fuel system control.
. Since portions of the fuel system shown diagrammatically in Fig. 1 are described and claimed in my Patent No. 2,670,725, only those parts will be referred to here which are necessary to an understanding of its application to the present invention. Where possible the same reference numerals are used as in my Patent No. 2,670,725. These parts are described under the section headed The Fuel Supply System, which section will follow the description now of my novel fuel injection mechanism. Subsequently I shall describe the Scavenging System shown in- Figs. 1 and 2.
The fuel injection mechanism The injector mechanism shown in Fig. 1 is a preferred form of my invention but it is understood that variations of proportions and dimensions may be made while still retaining the essential features of the device. In Fig. 1 only one of the six injectors 96 needed in a six cylinder engine is shown. It is connected to the common rail 35, to which the fuel is fed from the fuel supply system, by a header branch 100. As shown in Fig. 2 the injector is secured in the top of the engine cylinder 101 so that its spray nozzles 102 project into the combustion chamber 103.
The injector body 104 has a cylindrical bore 105 tapered at its lower end to form a plunger chamber 106, which chamber has a perforation 107 connected to the radially directed holes 102 forming the orifices through which the fuel is sprayed into the combustion chamber. The injector plunger 98 has a tapered end 109 to fit the end of the bore 105 in which it is reciprocable. It is pushed downwardly therein in timed sequence by the camshaft 108 and rocker arm 110. It is retracted by the spring 111.
The injector body 104 is bored to provide channels or passages 112, 113, 114, 115 for the feeding of fuel to and from the bore 105. The channels 113 and 114 terminate in ports 116 and 117 respectively in the wall of the bore 105 facing the plunger 98. I shall refer to port 116 as the fuel inlet port, and to port 117 as the scavenging port.
The ports 116 and 117 are located up the bore 105 far enough from the plunger chamber 106 so that when the plunger 98 is at the top of its upward stroke its edge 118, where the taper 109 starts, will not have uncovered the ports. In other words, when the plunger 98 is at the end of its upward stroke away from the nozzles 102 the inlet port 116 remains covered by the plunger. This means that for fuel to get out of the inlet port 116 down into the plunger chamber 106, it must go through a passageway in the plunger because there is too close a fit of the plunger in the bore to have the fuel leak down the bore wall past the plunger. If this close fit did not exist, the plunger would fail to function properly in forcing the fuel out of the plunger chamber 106 through the nozzles 102 and into the combustion chamber 103 because the pressure at the time of fuel injection is in the range of 800 pounds p.s.i. to several thousand pounds p.s.i. I have found that in an injector with a plunger in diameter, the distance from X to Y can be from A to one inch. (See Figs. 1 and 5).
It is important to keep the fuel inlet port 116 far enough up on the bore wall so that it is where the injector body is thick and is not subject to distortion. Another factor to bear in mind in locating the fuel inlet port 116 is the facility with which a passageway 124 may be drilled up the injector plunger 98. Thepoint to have in mind always is that the inlet port 116 must be high enough so that it is not uncovered by the edge 118 of the plunger when the latter is at the top of its stroke.
Another point to have in mind is that the cross channel 120 in the plunger 98 should have its ends 121 and 122 so that they align or index with the fuel inlet port 116 when the plunger is at the top of its stroke (see Figs. 4, 5, 7). The plunger preferably is grooved annularly at 123 to connect ports 121 and 122 and to make indexing with the port 116 a centainty. The distance from the lower edge of the annular groove 123 to the edge 118 isequal to the distance from X to Y minus the stroke of the plunger (see Fig. 5).
The passageway down through the plunger 98 from the cross channel 120 may take the form of a straight drilled hole 124 as shown in the drawings. Since reliance is placed on the pressure of the fuel supply mechanism to get the correct amount of fuel into each fuel injector, no particular metering or orifice size is necessary in the plunger 98 inasmuch as all conduits in all injectors will be of substantially equal size. If it were practical with production tools, the hole 124 would be made the size of hole 125, and no insert bushing would be needed, but since it is not practical to drill so small a hole for such. a distance, I employ inserts 126 as in Figs. 3 and 4. The small size hole has the advantage of tending to atomize the fuel entering the plunger chamber 106 as part of the fuel preparation before injection, and is as large a hole as is needed.
With my improved fuel injection system it is optional whether a return line from the injectors is provided, and where it is used I arrange for it to be effective only when the engine is being motored, as when an engine in a vehicle is coasting with the throttle closed. Under this operating condition some air may find its way up into the plunger chamber 106 in each injector and require disposal so it will not delay production of power when the coasting ends.
The injector plunger 98 as shown in Figs. 5 to 8 has an added feature to which attention should be called, namely, a check valve 127 secured to the end of a hollow shank 129 slidable in the channel 124. The check valve can close the channel 124 so that pressure from the combustion chamber cannot force the fuel back up the inlet channel 112. In Fig. 5 the check valve seats on the beveled rim 128 and in Fig. 7 it seats on the beveled end of the plunger. In Figs. 7 and 8, the clearance on the pin 129a determines the stroke of the shank 129, whereas in Figs. 5 and 6, the shoulder 129 determines the stroke. In either case is a spring used to keep the valve seated, as any difference in spring rates could affect the amount of fuel delivered to the several injectors. The valve in each case is caused to seat by the inertia force resulting from sudden downward movement of the plunger 98 and it is held seated by the pressure rise in the plunger chamber 106 during injection. Likewise on the upward stroke of the plunger 98 the inertia causes the check valve 127 to open so that by the time the fuel port 116 is aligned with the cross bore 120, there is an open passage down through the plunger into the plunger chamber, through which the fuel flows without restriction from the header 35. This assures equal feeding of fuel to each cylinder and is distinguished from earlier constructions where a spring loaded check valve had to be opened and held open by the pressure of the fuel. Under these latter conditions, any unequal spring loading or difference in area of the seating of the valve (where spring pressed) would cause an unequal feeding of fuel resulting in loss of horsepower and a rough running engine.
.The two-stage injector In Fig. 9is shown a further modification of my fuel injection system which might be characterized as a twostage system. A special cam 108a-is employed to actuate each plunger. The cam is fiattened at so the spring 111 retracts the plunger 98 earlier than normal and an additional amount above that required for normal injection. When so retracted, it is indexed with the fuel supply port 116 and receives the fuel charge. Then as the cam moves from the surface 108b to the surface M to N, it holds the plunger with the fuel inlet port 116 closed. The beneficial effects this has on the system are (a) that the injector receives its charge of fuel early and the inlet port 116 is sealed off before there is any appreciable pressure in the plunger chamber 106; (b) that the cam 108a moves the plunger 98 far enough to seal off the port 116 and to prevent the fuel or air from escaping back into the supply line 112; (c) that the plunger, after sealing off the port 116, still has its full stroke for building up its required pressure for proper injection and has not used up part of its effective stroke for the charging interval; and (d) that the additional stroke gives that much more sealing area along the surface of the plunger 98 and the wall of the bore 105.
Summary of the fuel injection mechanism Summarized, what my invention provides is a fuel injection system for an internal combustion engine including a combustion chamber 103, an injector body 96 secured therein having a bore 105 closed at its lower end to form a plunger chamber 106, said chamber having at least one orifice 107 therein to distribute the fuel into the combustion chamber; an injector plunger 98 reciprocable in the bore 105; cam means 103 for reciprocating the plunger in the bore in predetermined timed sequence; a fuel feeding mechanism 20 for supplying fuel to an inlet port 116 in the injector body, the injector body being characterized by having the fuel inlet port 116 in the wall of the bore 105, facing the plunger 98, and spaced along the wall so that when the plunger is at the end of its retraction stroke, the inlet port 116 remains covered by the plunger; the plunger 98 being characterized by having passage means 120, 121, 122, 124, 125 therein which open at 125 into the plunger chamber 106 and open at 123 adjacent the inlet port 116 in the bore wall, the latter opening 123 being spaced on the plunger 98 so that indexing with the inlet port 116 occurs only when the plunger 98 is at the end of its retraction stroke. In this way the fuel feeding means 20 will cause fuel to enter the passage means 123, 120, 124, 125 when the plunger is at the end of its retraction stroke thereby feeding a predetermined amount of fuel into the plunger chamber 106, which fuel will be forced through the orifice 107, 102 into the combustion chamber 103 when the plunger 98 is moved on its injection stroke.
Reference was made earlier to one of the advantages of my system being that the injector plunger 98 is working on a homogeneous compressible gaseous mixture, rather than on partially solid fuel. Fig. 10 assists in understanding what occurs where the introduction of the fuel into the plunger chamber 106 is done at or near the center. As the hot compressed air is forced into the plunger chamber 106 through the openings 102, 107, it impinges on the fuel entering from directly above it. This mixes the two and the air fuel mixture is evenly distributed in the plunger chamber 106. In Fig. 10 the direction arrows a indicate the stream of hot air from the combustion chamber and the arrows f indicate the fuel leaving the central passage 124 in the injector plunger 98. The impinging of these oppositely moving columns produces a desirable mixing and distribution of the fuel and air.
In the prior art devices where the fuel is introduced into the chamber through a hole on the side of the plunger chamber, a thorough mixing does not occur, therefore, in seating, the plunger will engage solid fuel on one side and air on the other side, resulting in undue strain on the injector parts. Also, in prior art engines, because the fuel is not completely mixed as it is injected into the combustion chamber, the fuel will be delayed in igniting and the engine will cackle.
The fuel supply system While the injector mechanism set forth herein is adapted for use with various forms of fuel fee-ding devices, it is particularly suited to use with the fuel. supply system of my Patent No. 2,670,725, which I have incorporated in Fig. 1 of the drawings of this present case.
The fuel apparatus may include, as a means to conduct fuel to the engine, either a distributor by which fiow to the respective injectors 96 is determined or may omit the distributor and have the fuel injectors for the respective cylinders connected to a common rail which in turn is connected to the fuel supply or conduit. In the case where a distributor is utilized, the period of overlap between a supply passage in the distributor and each of the passages leading to the respective injectors determines the time factor. In the case where the dis tributor is eliminated, each of the fuel injectors is provided with a cam operated plunger 98 which opens and closes a supply port 116 in the injector in timed relation to the operation of the engine and thus determines the time of opening.
In a fuel supply apparatus of the character herein contemplated where the fuel is maintained under constant pressure, a constant area of opening for the metering orifice would result in a greater fuel delivery to the engine as its speed decreases. This fact becomes evident in considering a distributor since the time during which the supply passage and each of the passages leading to the cylinders are overlapping increases with a decrease in engine speed. Similarly, the time that the supply port 116 in an injector is opened by the plunger is increased as the speed of the engine decreases. As a result, when the engine speed is pulled down by an increased load for a given throttle setting, the engine torque curve would rise above acceptable limits under such conditions, and thus overload the engine.
The invention of my Patent 2,670,725 overcomes this difiiculty by providing a variable orifice .in the line between a source of fuel under constant pressure and the distributor or fuel injectors, as the case may be, with the effective area of the variable orifice regulated by a governor to so control the fuel flow to the engine that any desired torque at maximum throttle opening may be obtained throughout the speed range of the engine. Such variable orifice may be provided by a needle or other type valve operable by the governor and connected with another variable orifice provided by a second needle or other type valve, also under control of the governor but acting oppositely to the first mentioned valve and operable to determine the maximum speed of the engine. In series with these two valves is a manually operable throttle which may also have the form of a needle valve. The apparatus is also so arranged that an idling speed control is provided, which is connected to the governor for automatic operation.
While my present fuel injection mechanism is illustrated in an embodiment like Patent No. 2,670,725 in which the fuel is maintained under substantially constant pressure throughout the speed range of the engine, the invention is equally applicable to a fuel pressure which may be varied with the engine speed but is constant for any given speed, and in that case the shape of the first mentioned needle valve is varied to compensate for such variation in pressure. The term constant pressure as used is therefore in the broader sense and is not limited to the idea of a constant pressure throughout the speed range of the engine.
The fuel supply system shown diagrammatically in Fig. 1 is of such form that it may be mounted at any convenient location on the engine and may comprise a main casing on housing 20, a pump casing 21 with the governor mounted on the housing 20. Fuel for the engine is adapted to be drawn from a fuel supply tank (not shown) through piping adapted to be connected to a fitting 22 carried by the pump casing and leading to the intake passage 23 of a pump 24 which may be of the gear type or other suitable form. The gear pump 24 discharges fuel into a passage 25 adapted to drain into a float tank 26. The float tank 26 is provided with a float controlled valve 27 to shut off the flow of fuel supplied by the pump 24 when the fuel in the float chamber reaches a predetermined level. When the valve 27 closes the discharge passage 25, a relief passage 30 controlled by a pressure relief valve 31 permits the fuel delivered by the pump 24 to be returned to the intake side thereof.
The source of fuel under constant pressure in the pres ent instance comprises a second pump 32 herein illustrated as a gear pump having a passage 33 for returning the fuel, in excess of that used by the engine, to the intake side of the pump 32 with a pressure regulator 34 mounted in the passage 33. The pressure regulator 34 is of the type which maintains the pressure of the fuel at the delivery side of the pump 32 at a constant value so that there will be little, if any, variation in pressure to affect the flow of fuel through the remainder of the apparatus. From the pump 32, fuel flows through conduit means provided by passages formed chiefly in the main housing 20, to the respective injectors 96, and the flow is controlled by valve means mounted in such passages. The main conduit or passage 36 extends from the second gear pump 32 and is connected to the common rail 35 through a series of valves. Thus the main conduit 36 has a manually operable v alve in the form of a needle valve 37 which constitutes the throttle for the engine. Beyond the throttle 37, the main passage is extended, as at 40, to open into a valve chamber 39. In the latter is a governorcontrolled valve 41, also in the form of a needle valve, cooperating with the opening of the passage 40 into the chamber 39 to provide a variable orifice, From. the needle valve 41 the main passage is still further extended, at at 42, to open into a valve chamber 47 having a third needle valve 43 mounted therein, which is also governorcontrolled. The needle valve 43 cooperates with the opening of the passage 42 into the chamber 41 to provide another variable orifice. From the latter, the main passage continues, as at 44, to the common rail 35 with a shut-off valve 45 placed in the continuation 44.
As mentioned above, both the valve 41 and the valve 43 are under the control of the governor, which is here indicated at 46. The governor 46 is illustrated as comprising a pair of centrifugal weights 50 pivotally carried by a rotating head 51 mounted on and driven by a main shaft 52. The drive shaft 52 is journaled in the governor casing to the left of casing 20 and is there provided with means (not shown) adapted to be connected to and driven by the engine.
The governor weights 50 are provided with inwardly turned fingers 55 adapted to engage a collar 56 mounted on a stub shaft near its end. The governor weights are so positioned that as the speed of the engine increases and the weights tend to move outward, the collar 56 will be moved to the left. Resisting such movement of the collar is a spring means, indicated generally at 57, and interposed between the collar 56 and the driving head 51. The collar 56 includes a sleeve 64 on which are provided a pair of spaced flanges 61 and 62. Mounted above the flanges 61 and 62 in the casing 20 and extending transversely to the drive shaft 52 is a rock shaft 63, journaled at its ends in the casing 20. Secured on the rock shaft 63, intermediate its ends, is a rock lever or yoke having a pair of spaced arms 65 embracing the drive shaft and having rollers 66 mounted on their ends and engaging in the groove formed by the flanges 61 and 62.
Thus, as the governor weights 50 move inwardly or outwardly in response to variations in the speed of the engine, the rock shaft 63 will be actuated in opposite (it? rections, depending upon the changes in engine speed.
Secured to the rock shaft 63, adjacent the ends thereof and on opposite sides of the main drive shaft 52, are a pair of levers 70 and 71, the lever 70 extending upwardly and engaging the end of the needle valve 43, while the lever 71 extends downwardly from the rock shaft and engages the end of the needle valve 41. Thus, the levers 7G and 71, as they are rocked by the rock shaft 63, will move the needle valves 43 and 41 toward their closed positions, depending upon the direction of rotation of the rock shaft. To move the needle valves 43 and 41 in an opening direction, springs 72 are mounted about the adjacent ends of the needle valves and bear at one end aaginst the main housing 20 and at their other ends against collars 73 provided on the ends of the valves.
It will be evident from the foregoing, and by an inspection of Fig. 1, that when the speed of the engine increases and the governor weights 50 move outwardly, the rocker arm 70 will move the needle valve 43 toward its closed position against the resistance of its spring 72, while the rocker arm 71 will move in a direction perrnitting the spring '72 on the needle valve 41 to move the latter toward an open position. Thus, the two needle valves 41 and 43 are moved oppositely in response to changes in engine speed. Since the needle valve 43 is moved toward a closed poistion as the engine speed increases, such valve is utilized to determine the maximum speed of the engine. Thus, the needle valve 43 will close sufficiently to decrease the flow of fuel to the engine through the main conduit when the engine speed closely approaches its maximum and will eventually completely close the main conduit to prevent all flow of fuel to the engine and thus limit its speed. It is obvious, of course, that as soon as the speed falls below its maximum, the needle valve 43 will open to again permit flow through the main conduit.
For a given setting of the various valves in the system, the amount of fuel delivered to the engine would increase with a decrease in engine speed. This would ob viously cause the torque curve of the engine to rise on decreasing engine speed and if the engine were operating at full throttle, it would cause an excessive overloading of the engine. By means of the valve 41, such a condition is compensated for to a predetermined extent so that the resultant torque curve of the engine may be of a predetermined character and preferably is substantially a flat curve with only a slight increase in torque as the engine speed decreases. While the valve 41 may be so constructed as to give any desired shape to such curve, the foregoing shape is preferred, although in some instances it may be more desirable to cause the torque to fall off at lower engine speeds.
In the present construction, the needle valve .41 moves toward its closed position as the engine speed decreases. Consequently, the flow of fuel through the main conduit may thereby be decreased, upon decrease in engine speed, to compensate for the tendency toward increased flow due to the longer period of opening in the injectors. The extent of compensation thereby obtained may be predetermined by so shaping the valve 41 as to provide a given area of flow about the needle valve for any given engine speed. The valve 41 may also be shaped to compensate for variations in pressure of the fuel.
The throttle valve '37 may be opened to any desired extent to control the speed of the engine, but when fully opened to its full throttle position, the valves 41 and 43 will exercise the necessary control over the flow of fuel. Thus, with the hand throttle 37 fully opened, if the load on the engine is light and the speed thereof tends to exceed the desired maximum, the governor 4,6 in response to such speed will shift the needle valve 43 toward its closed position to decrease the flow of fuel and ultimately to stop the flow of fuel so that the speed of the engine cannot exceed a desired maximum. However, if the load on the engine increases, when the throttle 37 is fully opened, the engine speed will tend to decrease, but any tendency for increased flow of fuel due to the increased time of indexing of the ports 116 in the injectors will be compensated for by the needle valve 41, which decreases the flow of fuel with a decrease in engine speed.
The common rail 35, as heretofore mentioned, is connected to the respective engine cylinders through injectors, one of which is indicated at 96 in Fig. 1. The fuel is delivered to each injector through an inlet port 116, the opening of which is controlled by a plunger 98 operated by the engine camshaft 108.
Each injector cam 108 is so designed that the period of time during which the port 116 is opened by the plunger 98 determines the time in which fuel is supplied to the cylinder. Since the plunger 98 is thus operated in timed relation to the speed of the engine, the period of time during which the port 116 is open increases with a decrease in engine speed. The needle valve 41, however, in this instance, under the control of the governor, compensates for the variation in time caused by changes in engine speed. The several plungers 98 in their respective injectors 96 are, of course, opened and closed sequentially and the opening of two or more injectors may overlap if desired.
The fuel control apparatus also includes means for providing a governed idling speed control for the engine. To this end, a by-pass 91 extends from the main conduit 36 around the throttle 37 to the needle valve 41 so that fuel may flow through the passage 91, when the throttle 37 is closed, to operate the engine at idle speed. The by-pass passage 91 opens into the bore in which the needle valve 41 is mounted at a point spaced from the tapered end of the needle valve, and a groove 92 is formed in the needle valve 41 at a point which registers with the opening of the passage 91 when the engine is operating at idle speed. Extending from the groove 92 is a diagonal passage 93 formed in the needle valve 41 and opening into the valve chamber 39 in which the needle valve 41 is located. At this time, since the engine speed is low, the needle valve 43 is in its fully opened position. Thus, suflicient fuel may flow from the pump 32 through the by-pass passage 91 to the groove 92 and the passage 93 in the needle valve to operate the engine at idle speed. Should the engine speed tend to increase slightly above the desired idle speed, the needle valve 41 will be moved by the governor to the left, and flow through the passage 93 in the needle valve will be decreased and eventually cut off by the movement of the needle valve to shift the passage 93 out of communication with the valve chamber 39. When the speed of the engine has decreased sufficiently, the needle valve 41 will be moved to the right to again permit flow through the passage 93. The engine will thus be maintained at idle speed under the control of the governor 46.
The scavenging by-pass Certain portions of Fig. 1 now to be described can be utilized with the braking and fuel shut-off mechanism disclosed in my co-pending application Serial Number 662,494 filed May 29, 1957, wherein provision is made for holding down the injector plungers 98 to stop the flow of fuel into the injectors, whenever the throttle 37 is closed and the engine is being rotated above idling speed as it is in a truck when coasting.
In the present case, I provide a piston 130 (on the injector plunger 98) fitted in a cylinder 131 formed in the top of the injector body 96. The underside of the cylinder 131 is vented to atmosphere at 132. The upper working side of the cylinder 131 is connected to a hydraulic pressure line 133 adapted to receive fluid under pressure from the line 134 through the solenoid actuated control valve 135 and the line 136. In Fig. l the solenoid 137 is shown in its energized position. When the sole- 'noid 137 on valve 135 is de-energized, the valve 135 is lifted by the spring 138 and the fluid in. the lines 133 and 136 flows back to the sump through line 140. This allows the spring 111 to lift the injector plunger 98, returning the plunger to normal action. The parts described function to hold the plunger 98 seated in the bore with an annular communication groove 141 aligned with the fuel inlet port 116 and with the outlet port 117. The purpose of this is to permit fuel to flow through the injector housing ducts 112, 113, 114 and for the purposes (a) of cooling the parts; (b) of maintaining a lubricant around the plunger 98 and in the bore 105; and (c) of scavenging any air bubbles that might have worked up into the fuel line. As shown in Fig. 2, additional annular lubricating passages 142 and 143 may be provided along the bore 105 to reach aligned annular lubricating grooves in the plunger 98.
The fuel that flows through the injector body under the conditions mentioned above is carried back to a float chamber 26 through the line 144, the common collecting header 145, the valve 146, and lines 147, 148 and 150. The solenoid 151 which opens the valve 146 is in series with the solenoid 138 so the hydraulic fluid which actuates the piston to hold down the plunger 98 is introduced simultaneously with the opening of the fuel return lines 114, 115, 144, 145, 147, 148, 150.
In Fig. 2, I show an alternative for the single valve 146 in the fuel return lines 144, 145, 147 of Fig. 1. In Fig. 2, each injector housing 96 is provided with its own cut-ofi valve 146a reciprocable in the bore 139. The valve is shown in Fig. 2 in its open position, in which position it is held by the same hydraulic pressure medium that is acting in the cylinder 131 on piston 130 to hold down the injector plunger 98. A passage 131a conducts the fluid into the bore 139 so it acts on the piston at the end of the valve 146a. A spring 149 will push the valve 146a downwardly the instant the valve (Fig. 1) closes off the hydraulic pressure medium and connects the conduits 133. 136 to the return 140.
As already explained, when the throttle 37 is closed and the engine r.p.m. is above idling speed (as when coasting), the idling ports in passage 93 will be closed so no fuel will be reaching the chamber 47. Under these conditions only, my system shown in Figs. 1 and 2 calls for the circulation of fuel through and out the injector housing 96 and back to the float chamber 26 for the reasons given just above. This fuel circulation I provide in the by-pass conduits 152, 153, 154, 155, which connect the fuel pressure pump 32 directly to the conduit 44 without going through the throttle 37 or the governor controlled valves 41 and 43. The manually adjusted valve 156 regulates the quantity of fuel that can flow in this by-pass line to lubricate and scavenge the fuel passages in the injector 96. The shut-off valve 157, shown open in Fig. 1, controls the admission of fuel to the by-pass line and has the hydraulic ram 158 resisted by a spring 161]. The hydrau' lic fluid conduit 161 is connected to the conduit 136, which means that the valve 157 is moved to open position whenever the injector plunger 98 is held down by the piston 130. A solenoid may be used instead to actuate the valve 157, just as a mechanical or other hold down arrangement may be used to hold the plunger 98 closed.
One way of actuating these various valves is to use the battery charging circuit in the electrical system of the vehicle, which includes a battery 162, a generator 163, and a cut-off relay switch 164 having contacts 165 which open when the engine r.p.m. drops to idling speed but close and stay closed when the r.p.m. is above idling speed. I couple this circuit from ground to the leads 166, 167 to solenid 151, then to the leads 168, 170 to solenoid 138, then to the leads 171, 172, 173, 174 to the switch 175, then to the lead 176 and to ground at 177. The switch 175 is closed only when the throttle 37 is closed.
There are alternatives to the use of the battery charging almanac cutout relay -165-to,contro1-the electrical circuit. For example, in'Fig. 1.1, 1 show a switch 169 to replace the switch 165 in Fig. 1. The switch '169 is actuated .by-the governor controlled arm :70, so that it opens when the engine slows down to a predetermined speed, above idling .speed. An advantage ,of this arrangement is that the switch 169 can be mounted for adjustment .to and from the lever 70 and in this way .allow for any desired time for the contacts in the switch to close .or to open.
Another alternative to the electrical control system for ,my invention is to have a mechanically operated valve ,means responsive to the governor 46, and to the foot throttle 29. At a predetermined speed, the valves would open and admit fluid under .pressure to .actuate :the piston 130, the piston 158 and the valve 146 in the fuel return :line.
It will thus be seen that I have provided .a fuel system in which fuel is circulated through the injector and back to the supply source, only when the engine is beingrotated above idling speed (this closes switch 165) with the throttle .closed (this closes switch 175); and that as soon as the throttle is opened, or the engine r.p.m. drops below battery charging (idling) speed, the fuel return line is closed (by de-energization of the solenoid 151) and the only outlet for the fuel is through the plunger chamber outlet 107, 102. Thus it will be seen that there is no possible route for the fuel to get into the combustion chamber when the engine is being rotated above idling .speed with the throttle closed.
Summarized very briefly, it will be seen that when the throttle 37 is open, the governor controlled valves 41 and .43, regulate the quantity of fuel reaching the feeder header T35 and the fuel injectors 98; and that the valve 146 shuts ,off the fuel return line during all conditions of the engine when firing. Also, when the throttle is closed and the engine is idling, the above condition exists. However, when the throttle is closed and the engine is rotating above idling speed, as when coasting (with the engine in gear and being motored by the momentum of the vehicle) the .by-pass line valve 157 opens to admit fuel to vby-pass the closed throttle ,37 and the closed valve 41, and to reach the injector chamber inlet 116, where the fuel is barred from entry into the plunger chamber 106 by the closed down injector plunger 98, but is admitted to the return line conduits 141, 115, 144, 145, 147, 148 and 150. As the engine speed drops below charging speed the relay switch 165 opens and the engine returns instantly to a normal operating condition with fuel ready at the port 116 to enter the plunger 98 and cleared of any air bubbles which, if they came up into the injector during coasting, were carried away in the fuel returned to the sump 26.
It will thus be seen that the device (a) wastes no fuel when coasting; (b) lubricates and cools the plunger mechanism by circulating fuel therein when coasting; (c) scavenges any air bubbles reaching the plunger ;by entraining them in the fuel being returned to the sump 26 when coasting; (d) avoids any dependence on resistance pressures in a fuel return line which could influence the rate of feed of fuel to the injectors, by closing off the fuel return line whenever the engine is firing; (e) and simplifies the supply of fuel for scavenging air bubbles and lubricating the injector plungers by lay-passing the gpvernor and throttle control means; and (f) separates the functions of lubrication and scavenging from the fuel feeding operation.
It will also be seen from the above that in my system when the engine is producing power, only the amount .of fuel is fed to the injectors that will be injected into the engine cylinders. In other words, in my system, I do not feed an excess of fuel, use part of it to power the engine and return the unused portion to the fuel source. It will now be clear that where this latter system is used,
if anything occurs to block or restrict the surplus or un- Fu-sed portion of the fuel in its return to the fuel source,
the surplus fuel will be backed up and will .be injected into the engine, causing it to run wild This is what occurred in the example given earlier where the mechanic made the mistake of closing off the return lines tothe two tanks. Not .only can this not happen .in the present system, but by keeping the fuel return lineclosed .when injection is occurring, I relieve the installerof the engine from having to take into account or pay any attention to the size of the fuel return piping, the size of the vent .in the fuel tank, or whether there are any restrictions in this piping.
-It will also be seen from the above that with the plungers 98 held down, the problem of having them stick .or .wear during coasting is eliminated, and that they are kept .freshly lubricated and cooled when the engine is being motored during coasting.
'It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.
"I .claim as my invention: I
*1. A fuel injector mechanism adapted for use in an engine having a fuel supply system with a line for returning to the fuel source the fuel not injected into the engine .cylinder, said injector including a plunger having a shoulder on its lower end; a housing, having a bore therein in which said plunger reciprocates; a first fuel passage in said housing connected at one end to the fuel source and ported at its other end on the wall of said bore above the upper limit of travel of the shoulder portion of the plunger; a second fuel passage connected at one end to the fuel return line and ported at its other end on the wall of said bore adjacent the like port in the first fuel passage, said plunger having a passageway ported at its lower end below said shoulder and ported at its upperend .on its cylindrical wall in position to align with the fuel passage port in the housing bore wall when in retracted position and to seal off from said port when said plunger commences its injection stroke; said plunger also having means for connecting the fuel supply port and the fuel return line port on the bore wall when the plunger is at the lower limit of its injection stroke.
2. The device of claim 1 in which there is a check valve in the passageway in the plunger to close during the downward stroke of the injector.
3. A fuel injector mechanism adapted for use in an engine having a fuel supply system, said injector including a plunger having a shoulder on its lower end; a housing having a bore therein in which said plunger reciprocates; a fuel passage in said housing connected at one end to the fuel source and having a pressure sealing delivery port at its other end on the wall of said bore above the upper limit of travel of the shoulder portion of the plunger; said plunger having a passageway ported at its lower end below said shoulder and ported at its upper end on its cylindrical wall in position to align with the fuel passage port in the housing bore wall when in retracted position and to seal off from said port when said plunger commences its injection stroke; and a check valve in the passageway in the plunger to close during the downward stroke of the injector.
4. A fuel injector for use on internal combustion engines, including: a housing having a bore, spray nozzles in its lower end, and a fuel inlet transfer port in its wall, a plunger reciprocable in the bore in said housing, said plunger being characterized by having an axial passage extending from its tip upwardly into communication with a cross-port in said plunger, and in which said cross-port is aligned with said fuel inlet transfer port only when said plunger is retracted to define therebelow a plunger chamber, said cross-port being further spaced away from said tip by a distance suflicient for the intervening cylindrical wall of said plunger and the adjacent wall of the bore in said housing to form a substantially fluid-tight seal, whereby the fluid contained in said plunger will be compressed from the instant said cross-port passes out of 13 communication with the inlet transfer port in said housing; and a check valve in said passageway to close on the injection stroke of said plunger.
References Cited in the file of this patent UNITED STATES PATENTS 14 Fabb Apr. 3, 1945 Cummins Mar. 2, 1954 Underwood Apr. 13, 1954 Wellington et a1. May 24, 1955 Shallenberg May 14, 1957 FOREIGN PATENTS Great Britain Oct. 27, 1927
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US1252254 *||Jan 1, 1918||fisherx|
|US2084057 *||Feb 23, 1937||Jun 15, 1937||Ethel Quarles French||Fuel injector|
|US2372694 *||Feb 4, 1942||Apr 3, 1945||Reconstruction Finance Corp||High-pressure fluid pump|
|US2670725 *||Jun 14, 1950||Mar 2, 1954||Cummins Engine Co Inc||Fuel supply apparatus for internalcombustion engines|
|US2674950 *||Aug 26, 1948||Apr 13, 1954||Gen Motors Corp||Fuel injection pump|
|US2708919 *||May 27, 1952||May 24, 1955||Gen Motors Corp||Diesel engine control system|
|US2792259 *||Jul 3, 1953||May 14, 1957||Int Harvester Co||Fuel injector for internal combustion engines|
|GB279193A *||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3146949 *||Oct 16, 1961||Sep 1, 1964||Cummins Engine Co Inc||Fuel injector|
|US3358663 *||May 18, 1967||Dec 19, 1967||Walter Miclo||Two-cycle internal combustion engine|
|US3902665 *||Jun 10, 1974||Sep 2, 1975||Ex Cell O Corp||Nozzle shut-off valve|
|US4009688 *||Mar 3, 1975||Mar 1, 1977||Toyo Kogyo Co., Ltd.||Rotary piston type engine|
|US4170974 *||Dec 16, 1976||Oct 16, 1979||Robert Bosch Gmbh||High pressure fuel injection system|
|US4211202 *||Sep 14, 1978||Jul 8, 1980||Daimler-Benz Aktiengesellschaft||Pump nozzle for air-compressing injection internal combustion engine|
|US4306681 *||Feb 21, 1980||Dec 22, 1981||Laitio Peter A J||Barrel and fuel injector utilizing the same|
|US4410137 *||Dec 31, 1981||Oct 18, 1983||Cummins Engine Company, Inc.||Miniaturized unit fuel injector employing hydraulically controlled timing|
|US4410138 *||Dec 31, 1981||Oct 18, 1983||Cummins Engine Company, Inc.||Unit injector cooled by timing control fluid|
|US4420116 *||Dec 31, 1981||Dec 13, 1983||Cummins Engine Company, Inc.||Unit injector employing hydraulically controlled timing and fuel shut off|
|US4693420 *||Aug 25, 1986||Sep 15, 1987||General Motors Corporation||Air-assist fuel injection nozzle|
|US4776516 *||Oct 9, 1987||Oct 11, 1988||General Motors Corporation||Air-assist fuel injection nozzle|
|EP0315328A1 *||Oct 7, 1988||May 10, 1989||General Motors Corporation||Pneumatic direct cylinder fuel injection system|
|U.S. Classification||123/298, 239/125, 239/584, 239/88|
|Cooperative Classification||F02D1/00, F02D2700/0282|