CA1165650A - Control unit for injector - Google Patents

Abstract

Abstract of the Disclosure A fuel control system for a diesel engine, the system including a source of fuel which is fed to a plurality of injectors (one injector for each cylinder of the engine), the mechanical operation of the injectors being controlled by a cam operated lever associated with the engine. The injector is formed with a main body having mounted therein a driving piston which is adapted to be driven by the cam operated rocker arm, a floating piston and a nozzle portion. The driving piston and the floating piston form a timing chamber in the space between the pistons and the separation between the floating piston and the nozzle element forming a metering chamber, A controlled amount of fuel is introduced into the timing chamber, the amount of fuel in the timing chamber determining the time of injection. Similarly, a controlled amount of fuel is introduced to the metering chamber, the amount of fuel determing the amount of fuel injected into the associated cylinder of the engine per engine cycle. The fuel being fed to the timing and metering chambers are controlled by individual control units, which may take the form of a variable orifice, the variable orifice being responsive to control signals generated by an electronic control unit. The output of the electronic control unit is responsive to engine operating conditions which are sensed by appropriate sensors. The control of fuel to the timing and/or metering chamber may take various forms, electrical or mechanical, a signal timing control unit being utilized for the timing function of the entire engine, and a signal control unit being utilized to control the metering function for the entire engine.

Description

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BACKGROUND OF THE INVENTION
_ _ _ _ _ Field of the Invention _ The instant invention relates generally to fuel injection systems, and more particularly to mechanically or electrically operated controlled control valves for separately regulating each of the timing and metering of fuel in a fuel injector forming a part of tha fuel regulating system, thereby permitting separate ad~ustment of both timing and metering of fuel from the various nozzle portions of the injectors in response to engine operating conditions.
Related ApplicationS
The invention i.n this Applica-tion is related to the invention disclosed and claimed in U.S. Patents 4,281,7g2 of August 24, 1981 and 4,235,374 of November 25, 1980 both being assigned to the assignee of the instant application~
Prior Related Systems Fuel injectors that are driven mechanically from the crankshaft of an internal comb~stion engine to deliv~r ~wel into the cylinders of the engirle are well known, see for example U.S. Patent No~ 2,997,994, issued August 29, 1961 The movement of the crankshaft is translated into a force by a lever mechanism which periodically depresses the p~p plunger in response to movement of a cam, cam follower and rocker arm mechanismO Since the rotation of the crank-shaft reflects only engine speed~ the frequency of the fuel injection operation was not readily adjustable with respect to other engine operating conditionsO Particularly, such adjustment was not permitted to be adaptive in controlling the injection process in response to specific enyine operating sd/~ "~

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conditions occurring immediately beEore or con-temporaneous with the injection process.
The above-referenced rela-ted U~S. patents disclose a single solenoid fuel injector which utilizes a primary pumping piston disposed to be actuated by the cam operated lever mechanism, a floating piston slideably mounted wikhin the interior of the injector, and a nozzle portion contiguous with the fuel induction or combustion chamber of the engine~ A
timing chamber is formed between the primary pumping piston and the floating piston, the amount of fuel being fed to the timing chamber determining the timing of injection relative to engine operations~ Also, a metering chamber is formed between the floating piston and the nozzle portion, the quantity of fuel fed to the metering chamber determining the amount of fuel being injected into each engine cylinder. The injector incorporates a single solenoid control valve which is utilized to control both the timing and metering for the injector. Particularly, upon downward motion of khe primary pumping piston, a control unit selects the time when the injection is to commence. When the injection is to start, the solenoid is actuated to form a hydraulic link between the primary piston and the floating piston by means of the fuel trapped in the timing chamber. Upon further downward motion of the pumping piston, the fuel in the metering chamber is injected into the engine in response to the pressure on the floating piston At a certain point in the downward travel of the primary piston, the floating piston '~
sd/`-~ -2-uncovers certain dump ports to cause the fuel in the timing chamber and metering chamber to be dumped back to the reservoir~ During upward motion of the primary piston, the solenoid valve still being energized, fuel is metered into the metering chamber for injection in the subsequent cycle and the end of metering is determined by the deenergization of the solenoid valve. The primary piston continues to travel upwardly filling the timing chamber with fuel. The injector is then prepared for a subsequent timing and injection cycle~
U.S. Patent NoO 3,951,117, grante~ ~pril 20, 1976 to Julius Perrl discloses a fuel supply system including hydrualic means for automatically adjusting the timing of fuel injection to optimize engine performance. The embodiment of the system shown in FIGURES 1-4 of the patent comprises an injection pump 17 including a body 151 having a charge chamber 153 and a timing chamber 154 formed therein~ The charge chamber is connected to receive fuel from a first variable pressure fuel supply, such as valve 42, passage 44, and line 182, and a timing chamber is connected to receive fuel fro~ a second variable pressure fuel supply by means of line 231. The pressure is controlled by means of pressure modifying devices 222 and 223. Fuel is delivered sequentially to each injector 15 within a set of injectors by means of a distributor 187.
The timing piston 156 i5 reciprocably mounted in the body of the injection pump, the piston 156 being disposed between the charge and timiny chambers. ~ plunger 163 ls reciprocably mounted in the body for exerting pressure on the fuel in the timing chamber from the cam mechanism 1640 The fuel in the ~iming chamber forms a hydraulic link between the plunger and the timing piston~ and the length of the link may be varied by controlling the quantity of fuel supplied the timing chamber. The fuel quantity is a function of the pressure oE the fuel being supplied thereto, the pressure, in turn, beiny responsive to certain enyine operaking parameters such as speed and load. Movement of -the plunger 163 in an injection stroke results in movement of the hydraulic link and the timing piston, thereby forcing fuel into the associated combustion cham~er.
The fuel in the timing chamber is dumped at the end of each injection stroke into spill port 177 and spill passage 176.

SUM~lARY OF THE INVENTIO~
With the system of the present invention, in one embodiment a variable orifice control device is provided for each of the timing and metering functions, a single device being provided for all of the injectors being utilized with a particular engine for each function. In another embodiment the timing and metering functions are controlled by controlled pulses of fuel being fed to each of the timing and metering chambers.
The system of the present invention includes an injector which is similar to the injector described in the above-referenced U.S. Patents 4,281,792 and 4,235,374 in that it contains a timing and metering chamber separated by a floating piston. However, in the preferred embodiment oE
the present system, a controllable variable area orifice is interposed between the source of fuel and each of the timing and rnetering chambers -to separately control the amount of fuel being supplied to the timing and metering chambers during the noninjection portion of the injector cycle.
In this way, a single timing orifice is supplied for the entire system, including all of the injectors for a single engine, and a single metering orifice is supplied to control the metering function for all of the injectors of ~: .
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~5--a single engine. This sy~tem has an advantage over ~he variable pressure type systems in that the quantity of ~uel supplied is a function o~ the square of the variation in fuel pressure wherea~ with a variable orifice the relationship is one to one between fuel flow and orifice area.
Thus, the system may be more precisely controlled and the ran~e of control need not be a5 great as would be ~he case with a variable pressure system. As may be perceived from a description of the present invention, the control, which is responsive to various engine conditions, may take several forms. These forms include both mechanical and electr ical control for each of the variable orifice control helmets. Thus, the instant invention easily lends itself to adaptive control of both the timing and metering phases of operation of an inter-nal combustion diesel engine. An alternative embodimen~
includes substituting pulse duration modulation of pulses of fuel being fed to the timing and metering chambers in lieu of the variable orifice control. Also a number of fixed duration pulses may be fed the chambers~ the control being accomplished by controlling the number of pulses.

Brief Description of the Dra~

FIGURE 1 is a schematic diagram il]ustrating the various portions of the diesel fuel control system incorporating the features of the present invention;
FIGURE 2 is a schematic diagram illustrating certain details of the injector and control valves of the system of the present invention;
FIGURE 3 is a schematic diagram of a mechanical control system for controlling the variable orifices in the con~rol elements of FIGIJRE 2;

FIGURE 4 is ~ sec~ional diagram lllustra~ing one form of a variable orifice device, which is elec~romag-netically operated;
FIGUR2 5 is a cross-sectional view oE another form of variable orifice which may be mechanically or electrically operated;
FIGURE 6 is a schematic block diagram of an electrical control system for the system of the present invention;
FIGURE 7 is a timing diagram illustrating the relationship between the cam profile associated with the cam shaft of a diesel engine and the quanity of fuel and vapor in the timing chamber and the quanity of fuel in the metering chamber, the cumulative flow and flow rate into the timing chamber, and the cumulative flow into the metering chamber;
FIGURES 8a to 8f illustrate the relationship of the cam profile with specific functions being performed by the injector during the engine cycle; and FIGURE 9 is a timing diagram illustrating the relationship between the cam profile and the pulse duration modulated pulses, which are utilized to control the flow into the timing and meterin~ chambers in a modified form of the system of the present invention.
Detailed Description of the Invention Turning now to the drawings, in particular FIGURE 1 thereof, there is schematically illustrated the major components of a fuel injection system employing a mechanically or electronically operated pair of control valves for regulating the timing and metering functions of each injector within the system. It is to be understood at the onset that a single control valve is provided for each of the timing end metering functions, ir.~ J)'!~

the con~rol valve being operated as a varia~le orifice, the orifice being varied in response to certain engine operating conditions. The system includes a fuel injector 10 that includes a connector block 12 and is controlled to deliver fuel through a nozzle 14 either directly or indirectly into the combustion chamber ~not shown) of an internal combustion engine 16, Although only one injector is shown, it should be noted that a set of identical injectors i5 employed within the fuel injection system, one injector being provided for each cylinder in the engine. The injector 10 is operated in synchronism with the operation of the engine through the reciprocal actuation of a follower 20, the follower 20 being in the form of a primary pumping piston being biased upwardly by heavy duty spring 18.
A cam 22 i5 secured to the camshaft 24 of the internal combustion engine 16. Cam 22 rotates at a speed which is a function of engine speed, the crankshaft being driven via meshing gears 23, 25 from the crankshaft 26.
The gear ratio of gears 23, 25 may vary from engine to engine depending on various factors, including, inter alia, whether the engine is a two cycle, or four cycle engine. The crankshaft is driven by the pistons (not shown) within the combustion chambers of the engine 16 in the usual manner. A roller 27 rides alon-3 the profile of the cam, and a push rod 28 and rocker arm 30 translate~
the movement of the roller into axially directed forces acting on the follower or primary piston 20. ~he forces act in upposition to the main spring 18 and vary in magnitude with the speed of the engine and the profile of the cam. The cam profile may be varied within the scope of the present invention to achieve a desired timing and primary piston speed as determined by the operation of the engine and the configuration of the control system.

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A reservoir 32 serves as a source of supply for the fuel used for control and to be dispensed by each injector 10, the fuel being withdrawn from the reservoir by constant pressure transfer pump 34. Filters 36, 37 remove impurities in the fuel and fuel i5 introduced to a control unit 38 by means of a conduit 40, the fuel being at supply pressure. The controlled fuel flow rate out of the control unit 38 is fed to the series of injectors, injector 10 being shown, through a pair of conduits 44, 46, one conduit 44 supplying fuel for the timing ~unction and the other conduit 46 supplying ~uel for the metering function, as will be more fully explained hereafter. The conduit 44 is connected to the block 12 of injector 10 by means of a conduit 48 and the conduit 46 is similarly connected to the block 12 by means of a conduit 50.
During the dumping and/or venting portion of the injector cycle, fuel is returned from the injector 10, and the other injectors in the system, to the reservoir 32 by means of conduits 54, 56, 58. This is the fuel that is not injected into the engine and is primarily the fuel used to control the timing function of the system of the present invention. However, it is to be noted that this circulating fuel is kept at a minimum due to the configuration of the system.
The fuel injection system of FIGURE 1 responds to several parameters of engine performance. In addition to engine speed, which is reflected in the rate of rotation of the cam 22 secured to camshaft 24, several sensors 60 may be operatively associated with engine 16 to determine, inter alia, engine speed, temperature, manifold absolute pressure, load on the engine, altitude and operator command. The sensors 60 generate electrîcal signals representative of the measured parameters and deliver the electrical signals to an electronic control unit 62, by means of a plurality of conductors 64. The electronic control unit then compares the measured parameters with reference values which may be stored wi-thin a memory in the elect~onic control unit, the rotational speed and angular position of cam 22 also being taken into account, and the electronic control unit generates a signal to be delivered to the con~rol unit 38. These signals, in turn, govern the control of the timing and metering functions for eac'n injector as determined by the control incorporated into the control unit 38O
The signals from the electronic contro] unit 62 are fed to control unit 38 by means of conductors 66, 68O
Referring now to FIGURE 2, there is illustrated the details of the injector, the controlled supply of fuel to the injector, and the drain configuration. The injectors are shown in schematic form7 however for a better understanding of the operation of the injector, reference is made to U.S. Patents 4,281,792 and 4,235,374 cited above. Specifically, -the injector lO includes a body member 70 which is divided into a timing chamber 72 and a metering chamber 74. The main drivi~g piston 20 is shown at the upper end of a cavity 76 formed within the body 70. The driving piston is adapted to be reciprocally drlven wi-thin the cavlty 76 along an axial direction -thereoE. 'rhe timing c~amber is formed by the lower end of the driving pis-ton 20 and a floating piston 80, and the metering chamber is formed by the lower end of the floating piston 80 and the bottom of the cavity 76. The output from the metering chamber 74 is fed to a nozzle 84 by means of a conduit 86, the increase in pressure in metering chamber 74 created by the downward motion of driving piston 20 increasing the pressure at the nozzle 84 to raise a needle type valve element 88 ayainst the force of a spring 90. This operation will be more fully explained hereafter.

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Referring fir~t to the timing func~ion, fuel is ~ed to an input conduit 92 from the reservoir 32 o~ FIGURE 1.
The fuel is directed through a variable orifice 94, the area of the orifice being varied in accordance with the 5signals being fed from electronic control units 62 to the control unit 38. Obviously, as orifice 94 is reduced, the flow of fuel through conduit 44 is similarly reduced and the amoun~ of fuel fed to the ~iming chamber 72 per unit of time is similarly reduced. The fuel flows 10through conduits 44, 48 to the timing chambers 72 through a one w~y check valve 96, the check valve permitting the smooth flow of fuel into ~he timing chamber, but precluding the fuel from flowiny out of the timing chamber through condui~ 48.
15The metering function is similarly controlled by means of a controllable variable orifice 100l the area of the orifice 100 again being controlled by control unit 8a in response to signals from the electronic control unit 62. The control of flow of fuel to the metering chamber 2074 is directed through conduits 46, 50 through a one way check valve 102, the check valve permitting the smooth flow of fuel into the metering chamber 74, but precluding fuel from flowing out of that chamber when the pressure is raised in meter.ing chamber 74.
25During the dump or pressure relieving stage of the operational cycle o~ the invention, as will be more fully explained hereafter, when floating piston 80 is driven to a point where the timing chamber 72 is in fluid communication with a conduit 106, the pressure within the 30timing chamber 72 i5 relieved to permit the fuel within chamber 72 to flow out of the timing chamber 72 through conduit 106 and a conduit 108 back to the reservoir through the drain conduit 58 and a check valve 110~ This permits the driving piston 20 to be driven to the full 3~extent of the downward motion of cam follower 30 depicted in FIGURE 1. In the preferred embodiment~ prior to th~
fluid communica~ion between chamber 72 and conduit 106, a passageway 114 in floating piston 80 i5 placed in 1uid communication with a conduit 116 to relieve the pressure in metering chamber 74. The fluid in chamber 74 flows through an internal passage way 120, the passageway 114 and conduit 116 to the drain conduit 54. A restriction 122 is provided between passages lQ6 and 116 to create a pressure spike below the restriction 122. This pressure spike is utilized to pressurize the upper end o~ needle valve 88 through a conduit 124. This aids in seating the needle valve 88 within the nozzle 84 to terminate the injection of fuel into the internal combustion engine.
The operation of the injector will be fully explained conjunction with the description FIGURES 8a through 8f.
However, for purposes of clarity, a brief description of the operation will be given at this point.
Assuming the driving piston 20 is at its lowermost position and floating piston 80 is also at its lowermost position, and the timing chamber 7~ and metering chambers 74 are not under pressure, the driving piston 20 starts its upward motion in response to the force of spring 18 (FIGURE 1) forcing khe injector up as the follower arm 30 moves up. This reduces pressure in chamber 72, causing floating piston 80 to rise. This ris~ of floating piston 80 also creates a reduced pressure in metering chamber 74. This reduced pressure, plus the pressure created in conduits 44, 46 by the pressure pump 34 on valves 96, 102 permits fuel to fill metering chamber 74 and partially fill timing chamber 72. The flow rate of ~uel into these chambers are controlled by variable orifices lO0 and g4, respectively. The filling process continues until such time as the driving piston 20 has reached its upwardmost posi~ion. The time it takes for driving piston 20 to reach this postion is, of course, determined by the engine speedO A~ the pi~ton 20 move~ downwardly, the valves 96 and 102 are sea~ed to increa~e the pre8sure in chamber~ 72, 74 af~er the vapor portion of ~he vslume in timing chambers 72 has been ~aken up by the volume of driving piston 20. Thereaf~er the increased pressure is fed to the end of noæzle 84 by means of the conduit 86 to raise the needle valve 88 and commence injection. The driving piston con~inues its downward movement until such time as the pressure is relieved in timing and metering chambers 72, 74O
Referring now to ~IGURE 3, there is illustrated a mechanical control for the orifices 94, 100 described above in conjunction with descriptive of FIGURE 2.
Specifically, the control system of FIGURE 3 includes an an operator controlled throttle pedal 130, which feeds an operator command signal to a speed responsive device 132.
The speed responsive device may take the form of a fly ball governor having a bias element which is variable in response to the chan~ing in position of the throttle pedal 130. The output of the speed response device may be a shaft 134 which is used to control the orifice of a variable orifice device 136, as is common in the art.
A variable-orifice timing valve 138 is controlled by a second speed-responsive device 140, which again may take the form of a variable bias fly~ball governor. Both speed-responsive device~ 132, 140 are driven by the engine. However, the variable input to the speed respon-sive device 1~0 takes the ~orm of a mechanical lever 142~
the output of which is fed to the speed responsive device 140 by means of a mechanism 144 (depicted as a single line~. The pivot point for the lever 142 is formed by a fulcrum device 146, the position of the fulcrum device 146 being controlled by the speed-responsive portion of the speed responsive device 132. What would norm~lly be the fixed point 148 is made variable in response to the position of ~he shaft 134. Thus, a feed-~orward mechanism is utilized to bias the speed-responsive device 140 in response to the operation of the speed-responsive device 132. This is utilized to control the area of the variable orifice device 13B by means of a shaft 150.
Thus, the variable orifice metering valve 136 is controlled in response to operator command and speed, and the timing valve variable orifice device 138 is controlled in response to engine speed and engine load, the engine load exhibiting itself through the operation of the linkage 144.
As stated above, the system of the present invention could also be operated electrically and the electrical operation may be accomplished by a variable orifice device such as depicted in FIGURE 4. In FIGURE 4, fuel is introduced into the control device by means of a conduit 156 and the output fuel i5 ed to the plurality of injectors associated with the engine by means of a conduit 158. The control of fuel through the body 160 of

2~ the control element is accomplished by varying the area of the orifice between a movable valve member 162 and fixed valve seat formed by edge 164. Thus, a~ the area between plate 162 and seat 164 is varied, the flow of fuel is similarly varied in a linear fashion. The position of valve plate 162 is controlled by means of a magnetic voice coil 166, in the preferred ernbodiment the input signal to the coil 166 being supplied from the electronic control unit 62 described in conjunction with FIGURE 14 The signal to coil 166 has a tendency to raise plate 162 against the force created by a spring lÇ8.
Another type of valve which could be substituted for the plate 162/valve seat 164 arrangement shown in FIGVRE
4 is depicted in FIGUR~ 5. The valve assembly of FIGURE
5 is a spool valve having a movable body member 170 which is slidably mounted in a body 172. An input condui~ 174 supplies fuel ~o a chamb~r 176 and the output thereof is fed to the injector by means of a conduit 178. Thus, as spool valve 170 i~ axially moved within the body 172l ~he fluid communication between ch~mber 176 and conduit 178 is varied. ~he spool valve 170 could be mechanically actuated or electrically actuated in a manner similar to that described in conjunction with FIGURE 4.
Referring now to FIGURE 6, there is illustrated a schematic block diagram of an electronic control system for use with the fuel system of the present invention. A
comparison of the functions of FIGURE 6 with those of FIGURE 3 will indicate an analogy between the mechanical and electrical configurations. Specifically, an operator command signal is fed to a throttle sensor circuit 180 by means of an input connection 182. An actual engine speed signal is generated by means of an engine speed sensoe circuit 184 in response to the output of an engine speed sensor 186. The two signals from circuits 180, 184 are compared by a comparator circuit 188 and the difference between the two outputs generates a control signal on a conductor 190, which control signal is utilized to control a variable area control circuit 192. The output of the variable area control circuit 192 may be utilized to control the variable orifice 100 described in conjunction with the description oE FIGURE 2. This signal is fed to the variable area device by means oE a conductor 194. The comparator 188 operates to null the signal on conductor 190 to fix the position of the variable area device connected to conductor 194 during steady state operations of the engine.
The output signal on conductor 194 is also fed to a divide circuit 196, which is provided inputs from control circuit lg2 by means of a conduc~or 198, and a speed signal from the speed sensor circuit 184 by means of conductors 200, 202, 204. The output signal from the va~iable area control circuit 192 is representative of power, the operator commanded signal input 182 as compared to the sensed signal at input 186, and this power signal is divided by a speed signal on conductor 204. Thus, the output of circuit 196 will provide an engine load signal on a conductor 208. This signal is u~ilized to aid in the control of the variable orifice timing circuit, which includes a variable area control circuit 210. The output of circuit 210 controls the variable area orifice 94 described in conjunction with FIGURE 2 by means of a signal on conductor 212. The input to the variable area control circuit 210 includes a speed signal from a conductor 214, the speed signal being trimmed by the load signal on conductor 208 by means of a load trim circuit 216. The main signal being fed to the variable area control circuit 210 is the speed signal on conductor 214 as modified by the load signal on conductor 208.
Thus, a purely electrical control for the system of the present invention has been provided with the sy~tem of FIGURE 6. It is to be understood that other control laws may be utilized to control the variable orifice devices to fit the needs of a particular diesel engine.
Referring now to FIGURE 7, there is illustrated the timing diagrams for the control devices of the present invention. Specifically, the cam profile is ~hown pictorially by means of a profile line 220 at the upper portion of FIGURE 7. When the cam reaches the uppermost portion of the stroke of the main driving piston and starts on a downward travel, it is seen that a cumulative flow into the metering chamber is derived and depicted in FIGVRE 7 by means of dashed line 222. Similarly, the timing chamber accumulation of fuel is depicted by dashed line 224 and the amount of vacuum or vapor space in timing chamber is depicted by the distance between line 224 and line 220.

Another depic~ion of the timing chamber is illustrated in the middle graph wherein the cumulative flow into the timing chamber at the time the downward stroke commences is shown by a straight line having a positive slope which ~erminates at the point of injection. Thus, a constant flow of fuel into the timing chamber creates an accummulation of fuel. For purposes of illustration, this accumulation is shown as being linear~ Injection occurs and is depicted by the horizontal line terminating in the dump mode of operation. Upon dumping, the pressure or the flow in the chamber is substantially reduced and the cycle commences again. The flow rate into the timing chamber is also depicted in the middle graph and is shown to be generally rising function which levels off to a constant flow rate until such time as injection occurs. At that time, the flow rate ceases until the dump mode occurs. Upon dumping, the fuel accumulated in the timing chamber is returned to the reservoir as depicted by the negative flow.
A similar graph is illustrated at the bottom of FIGURE 7, but relating to the metering chamber. However, for purposes of clarity, the flow rate diagram has been omitted. Thus, the flow accumulates in the metering chamber from the zenith point on the cam profile until such time as injection occurs. At injection, the flow ceases until the dump mode is achieved. At that time the flow goes negative to depict the slight flow of fuel out of the metering chamber.
Referring now to FIGURES 8A to 8F, which best depict the operation of the injection of the system of the present injectiont there is illustrated a cam profile in FIGURE 8A and various phases of operation of the injector in FIGURES 8B to 8F. It is to be understood that the injector shown is merely a graphic showing and is not

3,t~ 3 ~17-intended to actually represent a commercial embodimen~ o~
the injector. For purposes of clari'cy, the reerence numerals utilized in conjunction with the description of FIGURE 2 will also be utilized in conjunction with the description of ~IGURES 8s to 8F.
FIGURE 8A illustrates the cam profile and certain positions on the cam profile have been noted with numerals 1 through 6. Numerals 1 through S correspond in operation to FIGUREs 8B through 8F respectively, and numeral 6 corresponds to the starting point at numeral 1.
At position 1 on FIGURE 8a, the cam has reached a point whereby the piston 20 is at its lowermost position, corresponding to the injector of FIGURE 8B.
Subsequently, the driving piston rises to reach position 2, is at a constant position between positions 2 and 3, and is driven downwardly at position 4 and 5. The driving piston 20 then reaches starting point at point 6 again.
Referring to FIGURE 8B, the driving piston 20 is at it~ lowermost position and timing chamber 72 and metering chamber 74 have been relieved of pressure therein.
Valves 96 and 102 are seated, needle valve 88 is seated in nozzle 84 and fuel is ready to be fed to the injector in response to the operation of the engine.
Referring now to FIGURE 8C, it is seen that the driving piston 20 has risen to the upper level and vapor has been created in the timing chambers 72. The floating piston 80 is generally down at the bottom of the cavity in the body of the injector~ It is to be noted that valves 96 and 10~ are open to permit fuel to flow into the timing chamber 72 and metering chamber 74. The needle valve 88 is still seated in ~he nozzle 84.
During the travel from point 2 to point 3 in FIGURE
8A as shown in FIGURE 8~, the timing chamber 72 has been partially filled with fuel to the level indicated while the check valve 96 is open, and metering chamber 74 is similarly filled, check valve 102 b~ing open It is to be noted that the ~loatin~ piston 8~ has moved up, thereby closing the entrance to passages 106 and 116. In this way, fuel is precluded from spilling into the drain conduit 1030 Referring now ~o FIGURE 8E, the piston 20 is now at point 4 and is starting the downward travel to compres~
the vapor and pressurize the fuel in the timing chamber lQ 72 and metering chamber 74. The check valves 96 and 102 are closed due to the increased pressure in chambers 72, 74. The increased pressure in chamber 74 unseats the needle valve 88 in nozzle 84, thereby injecting fuel into the engine from the end of nozzle 840 The fuel is fed lS from the metering chamber to the nozzle end by means of the conduit 124.
When the driving piston 20 reaches an area toward the bottom of the stroke, FIGURE 8F and position 5 on FIGURE 8A, the entrance to conduit 116 has been opened and fuel flows from metering chambers 74 through conduit 120 and conduit 114. Thus, the `pressure within the metering chambers 74 is relieved. As explained previously, the re6triction 122 creates a pressure spike in conduit 124 to ~orce the needle valve 88 into the closed position. Similarly, the entrance to conduit 106 is uncovered, thereby permitting further downward travel of the floating piston 80 to thereby dump or vent the fuel from the timing chamber 72. Further downward movement of driving piston 20 from position 5 to position 6 on FIGUR~ 8A causes further fuel to be durnped from timing chamber 72.
As an alterna~ive to the above described control mechanisms and circuits, the amount of fuel in the timing and metering chambers may be controlled by pulsing an on/off control valve which is positioned in the same part of the hydraulic circuit as the variable oriEice control elements are positioned. With the alternative control scheme, each injector would be provided with a controlled pulse of fuel for both the timing and metering chambers for each of the injectors. Thus, the on/off valve which replaces the variable orifice device will provide at least a single pulse of fuel for each injector per engine cycle, multiple pulses being contemplated. This may be accomplished by reversing the lobe on the cam such that lobe is represented as a depression rather than a projection on the cam with the remaining portion of the cam such that it will hold the main piston down during the period metering of fuel into the timing and metering chamber is not occurring.
This is graphically illustrated at the top of FIGURE
9, the cam profile being shown as a dashed line. Thus, a window is created for metering fuel into the injector during the kime that the cam pro~ile is at the low point A. When metering is not occurring, the cam is at a high point B and remains there until metering is de~ired fo~
that injector. It is to be understood that the remaining injectors are all at the high point to preclude metering.
Thus, each injector is isolated, one rom the others, during metering there being no overlap of the depression a~ point for any two or more injectors~
Referring particularly to FIGURE 9, there is illustrated a timing diagram, which is correlated to the cam profile which i5 illustrated as the top curve in FIGURE 9. It is to be understood the cam profile may be the negative of that shown. The middle curve, designa~ed flow rate into timing chamber, illustrates a fuel pulse which is fed to the timing chamber of a single injectox.
As is seen from the dashed lines, the fuel pulse can be either lengthened or shortened, depending on the amount of fuel which is desired to be introduced into the timing 5~

chamber. Similarly, ~he metering chamber pulse, illustrated at the bottom of FIGURE 9, i~ ~ed ~o the metering chamber of the injector of FIGURE 2. Again, this time-duration p~lse may be lengthened or shortened, depending on the amount of fuel desired to be introduced into the metering chamber.
With the state of the technology of the spark ignited gasoline engine ar~, it is conceived that a sequen~ial electronic control unit utilized with such spark ignited engine, with the proper input sensing signals to sense engine parameters, could be utilized to generate the pulses disclosed in FIGURE 9. Thus, a sequen~ial pulse-duration modulation of the quantity of fuel being introduced to the timing and metering chambers of a diesel fuel injector may be utilized as a control law for the system of the present invention; as an alternative modification.
Many changes or modifications in the above described embodiments of the invention may of course be carried out without departing from the fair meaning and scope of the invention disclosed. Accordingly, the scope of the invention is intended to be limited only by the scope of the appended claims.

Claims (5)

I claim:

1. A control system for controlling the supply of fuel from a source to an internal combustion engine having a crankshaft and a plurality of cylinders, the system com-prising an injector having a body, a primary pumping plunger and a secondary plunger positioned within said body for move-ment therein; a nozzle situated contiguous with the engine;
a timing chamber defined in said body between said primary pumping plunger and said secondary plunger; a metering chamber defined in said body between said secondary plunger and said nozzle; timing and metering passages in said body of said injector for receiving pressurized fuel and trans-mitting said fuel into said timing chamber and said metering chamber; means for controlling (1) the timing of the dis-charge of fuel from the metering chamber through the nozzle and (2) the quantity of fuel stored in said metering chamber including a variable orifice control valve in each of said timing and metering passages for controlling the flow of fuel from the source to said timing chamber and said metering chamber, and means for controlling the variable orifice of each of said variable orifice control valves in response to engine operating conditions, including means for controlling said metering orifice in response to engine speed and an operator command.

2. A system of Claim 1 wherein said timing control valve is controlled in response to an engine speed and operator command signal, and a further engine speed signal.

3. The system of Claim 1 wherein said timing control valve is controlled as a function of engine speed and engine load.

4. The system of Claim 2 wherein said control is an electrical system.

5. The system of Claim 3 wherein said control is an electrical system.