CA1100836A - Fuel injection timing and control apparatus - Google Patents

Abstract

FUEL INJECTION TIMING AND CONTROL APPARATUS
Abstract of the Disclosure The disclosure relates to a fuel injector for an internal combustion engine and, more particularly, to a fuel injector for a compression-ignition type engine. The fuel injector precisely meters fuel and accurately times the start and duration of fuel injection in response to a multiplicity of operating parameters totally independent of a mechanical connection to the engine.

Description

110(:~836 Background of the Invention Internal combustion engines are subJect to variations in power output, smoothness of operation, economy, emissions, etc.
incident to variations in fuel-air ratio, unequal distribution of fuel-air -~ixture to each combustion chamber, the timing of ignition in relation to the position of the piston in the-cylinder, acceleration and deceleration , transients, the type and amount of fuel provided, as well as external operating parameters, for example, -engine load, R.P.M., ambient air .
~ressure and temperature, etc. ~ addition to the foregoing parameters, compression ignition engines are faced with the functional need for initial - injection of fuel during the compression stroke. Accordingly, the high -gas pressure developed in the combusffon chamber prior to the start of -~uection inhibits injection requir~g fuel to be injected at a relaff~rely }ligher pressure. High fuel pressure is i ypically achieved by pumping ~uel from a low pressure rota~r or gear pump to a bigh pressure pump.
-~Iigh pressure pumps n~ay utilize ro~y, displaceme~t, or other means -~o pressurize fuel. A typical high-pressure pump comprises~a positive displaccment piston driven by a c:un mounted on :m en~ine-driven camsh~ft.
~he c3mshslft i9 conncctcd by v~rious means, such ~g ge3rs, chains, rockcr-~rms, followcr 3~sem~1ics, etc. to the en~inc cranksh3ft.

~ thor known mcan~ Gl' prc~uurlzin~ ruel includ(: clcctrlc~l, mccllan~cal, -hydraullc, an~l clcctro-mcc11.-nic~ ump :;y~tems w~lich scpar.ltely, or {n combin:lt~on, cle~clop suîficlcnt fucl prc~surc to open a ~ralve as3eml>1y which in turn injt:cts thc iucl into thc combustion chambcr.
Since comprcssion-iE~n~ition occurs at a variablc point in tLme subsequent to injection, the efficicncy of the prcssure-tempcrature -'ouild-up within the combustion chambcr during thc compression and e l~pansion cycle in relation to crankshaft position and the consequent useful energy output is sensitive to many variables not the least of which is timing and duration of injcction. Present compression-ignition engine fuel injection systems typically rely on direct coupling of the timing -mechanism controlling fuel injection to the engine crankshaft by means of said gearing, chains, cams etc. In most cases, fuel in]ection timing .is relatively fixed in terms of crankshaft position, notwithstanding that -some variation in the timing of fuel injection in terms of crankshaft position - . . . . .
ean be achieved by mechanical movements or mechanisms which align ~elief ports or entry ports or both It is also kno.lrn to use helical flow ..
-.paths on the fuel injector plunger shaft-which can be rotated to adjustably :meter fuel and/or control timing by selective aligDment of the fuel entry ~port and/or fuel relief port. In other prior art. devices, mech~nical .: . . .
levers or other mechanisms open or close fuel entry or relief ports to ;aceomplish fuel injection metering and tirning. -' -~hus, a need exists for a Euel injection system that is capable - ~f precisely controlling and varying the timing and ~luration of fuel . . . . .
.. ~uection in relation to crank angle, as well as havil~g the capability of . .
~reeisely metering the proper quantity of fuel, in r~sponse to the totality .
o~ operating conditions. .

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11~)(~836 With rcspcct to mctcrin~, most known dircct injcction systcm~
~ffect fllling of a cavity upstrcam oE thc injcctor nozzlc with thc CX;lCt -~nount of fucl to bc injcctcd. Thc fucl in thc c~vity i~ actcd upon ~y a -~iston to providc the prcssurc nccessary ior injcction.
In distribution typc injectors, eithcr rotary, displacement, or other ~neans are used to pressurize fuel at which time a selector mechanism directs the high pressure fuel to rcmote injectors at or near each combustion cylinder. The high pressure fuel flows to each injector nozzle causing the DOZZle to opcn and to inject the fuel until a subsequent pressure drop closes the nozzle. Such known systems exhibit delays and - inaccuracies related to the remoteness of the pressurizing means and the -injection mechanism and are comparaiively ;nefficient for controlling --~timing and the quantity of fuel injected.

- Summary of the Invention - ~ ; r The fuel injection system of the instant in~7ention is aciuated independen.ly of any mechanical connection to the cranl;shaft. The high -.
--~ pressure fuel pump is not ins7olved in the timing or metering of fuel . - , . - - i -- injection or actuation of the fuel injection nozzle. Fuel injection t;ming -- is related to a precise position of each cylinder and variations in the -sauantity and rate of injection are computed externally from the fuel -injection mechanism by various means which include, but are not limited to, ~electronic, electro-mechanical, electro-ma~netic, opto-electronic, piezo-~electric, and other tempçrature, pressure, and position determining sensors, position switches and devices which measure en~ine operating and environ-~mcntal parameters. ~ multiplicity of parameters involved in the combustion ....
pr~cess can bc accommodatcd. These includc, but arc not limited to, cranlcshaft position, R. P. M., tcmpcraturc of the ambicnt air, coolant~, ~ucl, cxhaust, and oil, fucl 3nd air prcssurcs, load, cnginc torquc, .' ' "~ ' '' ''.
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Vch{clc spccd, transm{~s{on nnd throttlc posltion, fucl-~{r ratios, eom-bustlon prcssurcs, combustion tcmpcraturcs, combustion a{r-mas9 nOw .~nd ~upcrch~r~cr prcssures.
Moreovc~; it i3 contemplated that memory devicc~, such - n8 random-access-memories ~RAMS) and/or read-only-rnemorics (ROMS), can be utilized to store either computed data (in the instance of RAMS) or ean be progr.~nmed (in the instance of ROMS) to reflect changes in injection timing; rneter fuel quantity, or rate of nOw of metcred fuel for a multiplicity of operating conditions. Furthermore, it is contemplated that merely a change in a programmed memory can render a single --injection device usable in different engines.
The invention incorporates an accumulator along with its ~associated pressure relief and other valving which operates to disp~se ''' ', "- ', ' : . ", I
iuel directly to the engine combustion chamber. Thus, the invention pro-vides a means of utilizing very high fuel injection pressures and fuel ecting pressures which can be varied quickly, almost instantaneously, -.~ithout the delays normalb associated with present devices. These -featu~s facilitate improvements in fuel econorny and engine operating -efficiencies and design improvements in injection spray mechanisms as rell as shorter periods of fuel injection, not heretofore practical. 1 -More particularly, the armature of an electromechanical ~olenoid is util;zed as a direct fuel injection control device. The arrnature - ~8 not affected by high fuel pressure heads or dynamic shut-off forces.
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-'By virtue of its immersion in fuel, it is self lubricating, cooled and - , ' , . ~
-~dynamically dampencd to inhibit undesirablc vibration modcs.
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The armaturc mny utilize clcctro-magnetic, ~prinE~, or othcr rcstorin~ forccs. Since tho mcch~nism docs not cffcct pressuri~ation of tllc fucl, clcctromngnctic force and spccd rcquircmcnts nccd only be .' ' ' , ' . . .' _ ,~ ,. . . ,.
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' , U~36 proportioned to the operating requirements of the engine, for example, in a sophisticated application, to change the rate of openins of the injection orifice, or in its most simple applica-tion, to effect only an "open~close" action. In one embodiment of the invention, the electro magnetic solenoid is housed internally of the fuel accumulator of the injector, In another form of the invention, the solenoid may be disposed externally of the pressurized fuel in the accumulator. More than one electro magnetic solenoid may be utilized either to amplify the forces on the armature, eliminate return springs, or to provide opposing forces to the "open" and "close" action. In some applications, more precise movement and/or speed of armature movement can be realized with more than one solenoid. A variable and controll-able pressure relief valve is connected to the high pressure accumulator so as to provide for safety, as well as allow variations in fuel quantity metering, In summary of the above, therefore, the present inven-tion broadly provides an electrically controlled liquid fuel injector for converting a conventional pressure excited fuel injector system of a diesel internal combustion engine to a non-pressure excited injection system, the injector comprising an injector housing adapted to ~e mounted in the space and position of the conventional pressure excited fuel injector in direct communicating relationship with the combustion chamber of the diesel internal combustion engine, an accumulator in the housing, the accumulator includin~ means for maintaining the pressure of liquid fuel therein relatively constant incident~to changes in the volume of fuel in the accumulator, a fuel pump in the housing comprising a piston adapted to be mechanically sd/~

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ll~U836 driven directly by the engine in direct relation to the speed of rotation thereof for pressurizing fuel in the accumulator, a fuel in~ection nozzle communicating with the accumulator and the combustion chamber of the diesel internal combustion engine, a fluid flow control valve mechanically and functionally independent from the fuel pump and having fluid flow control ports communicating directly with the accumulator and the injection nozzle for controlling the flow of fuel from the accumulator to the injection nozzle, the valve being movable between an open and closed position independently of the pressure of the fuel in the accumulator~ an electric solenoid for controlling movement of the valve independently of the pressure of the fuel in the accumulator, and means for energizing the solenoid independently of the fuel pump and pressure in the accumulator in response to selected engine and environmental parameters, Brief Description of the Drawings Fig, 1 is a cross sectional view of an improved fuel injector in accordance with one embodiment of the invention, Fig, 2 is a cross sectional view, similar to Fig, 1, illustrating a modified embodiment of the pre~ent invention utilizing dual solenoids, Detailed Description of the Invention Referring to figure 1 of the drawings, a fuel injector 10 in accordance with the present invention comprises a housing 12 having a manifold 14 and a tubular barrel 16, The manifold 14 has conventional fittings 18 and 20 for the acceptance of relatively low pressure fuel into the manifold 14, sd/ -5A-.: . : . - ,., - . , .-:
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The fucl plun~cr 22 l~ ~lid;lble in a bore 23. Tho plun~er 22 i~ biaYed upw;lrdly, as :~een in thc draw~ngs, by a plun~er sprin~ 2~, The plungcr 22 has a follo~vcr portion 26 that is engagcable by ~ cslm 2 on a camshaft (not shown) of an cn~inc ~not shown).
The plungcr 22 has a piston 30 at the lowcr end thereof which acts a~ainst fuel in a pumpin~ chamber 32 to pressuri~e and pump the Iuel past a check valve 34 into a plenum chamber or accumulator 36 ~uteriorly of the barrel 16.
The manifold 14 is provided with an accumulator piston 38 . that is slidably disposed in a bore 40. .The piston 38 is biased downardly, as seen in the drawings, by a spring 42. The piston 38 is movable upwardly ... against the bias of the spring 42 to maintain fuel pressure relatively . .
. eonstant within the accumulator 36 upon injection of fuel into the working eylinder of an engine as will be described. :. .. . .
The charnber 40 is provided with a relief passage 44 ~hat -~.
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-eommunicates with an outlet line 46 on the back side of a check valve 48.
~he accumulator chamber 36 has a relief passage SO that communicates ~vith the high pressure side of the check valve 48 to relieve pressure within rthe accumulator 36 above a.predetermined level. In this manner, high -pressure fuel is constantly flowing through the intake manifold 14, accumùlator 36, through outlet line 46, outwardly of the manifold 14 to a fuel - reservOir (not shown) to provide an adequate supply of fuel for injection into a working cylinder of an engine as well as to effect cooling of the -in~ector 10~, In aecordance with the present invention, injection of fuel ~under pressure into a worlcing cylinder by the fuel injector 10 is controlled by a solenoid 60 comprisin~ a coil 62, a cylindrical outer eas~n~ 64, ., , ~ .
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, ll[)U836 , ~n Inner pole p~ece GG, and D. ~ bla cylindrIc;ll or 81ccvc-lllcc a.rm3ture (iU.
The armature 6~ i9 hi;:lsed to the normally opcn condition by n spring 70 -~vhich i~3 seatcd on a radial shouldcr 72 on thc armature 6û.
~ he solcnoid G0 i3 controlled by a conventional state-of-the-. art electronic assembly 74, such as but not limitcd to, suitable sensor transducèrs, an input-output signal conditioning seetion, a microprocessor or other suitable electronie proeessing unit, and a driver seetion to pro-vide sufficient energy and timing to actuate the solenoid and/or other electro-mechanical dcvice in the conventional m~nner. The electronic .assembly 74 senses and correlates the engine and environmental parameters -- discussed hereinbefore and translates them into an appropriate eleetrical ~:ignal to the solenoid 60.
The lower end of the armature 68 is provided with a pair of . :transverse bores 80 and 82 whieh, when aligned with eomplimentary bores :84 and 86 in a fixed central mandril 88, permit flow of pressurized fuel -from the plenum 36 downwardly through a eentral bore 90 in the mandrill 88 ~nd out~,vardly through diseharge passages 92 and 94 in a spray tip 96 of the injector 10. The mandril 88 is non-magnetie to insure magnetie - ~effieieney. A nut 104 secures the coil 62, armature 68 and mandril 88 together as a sub-assembly.
-Referring to Fig. 2, a modified injector lI0 comprises a --~ai.r of opposed solenoids 112 and 114 having eoils 116 and 118, eylindrieal -outer easings 120 and 122, pole pieees 124 and 126, respectively, and a eommon slidable eylindrical armature 128, The armature 128 is biased . . between the open and elosed condition by eontrolled andlor seleetive energization of the eoils 116 and 118. Thus, eontrol of the injcctor 110 e~n be effeeted by an "on-off" signal or by a "proportional" sign;

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'" ; ' ~. ..... , ,- ' -' . , '' , ' ' ' ', '' ; ~ 836 ~~he lower cnd of the armaturc 1 2n ~s provlt~ctl wlth ~ pair o~ tr3nsvcrsc borcs 130 ~nd 132 which, whcn aligncd with coinplimcnt~ry bores 13~ and 13G in a lowcr tip portion 13~ on thc housin~ o~ the ~olenoid 114, permit flow of prcssurizcd fuel from tllc accllmulator 36 downwardly throuE~h a central bore 140 and out vardly through discharge passages 142 and 146 in the tip 138. ~ lower end portion 148 and an upper end portion lS0 of the armature 128 are non-magnetic while center portions 152 and 153 are magnetizable to maximize the efficiency of the .
solenoids 120 and 122.
From.the foregoing it should be apparent that pressurization of fuel within a plenum chamber of the injector is disassociated from timing and duration of fuel injection which is controlled solely by tho . .
-energization of a solenoid. In this r;lanner, fuel injection is rendered responsiSle to a number of parameters of engine performance which heretofore have been incapable of integration into the injector control ... . . .. . .
function.
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Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electrically controlled liquid fuel injector for converting a conventional pressure excited fuel injector system a diesel internal combustion engine to a non-pressure excited injection system, said injector comprising an injector housing adapted to be mounted in the space and position of said conventional pressure excited fuel injector in direct communicating relationship with the combustion chamber of said diesel internal combustion engine, and accumulator in said housing, said accumulator including means for maintaining the pressure of liquid fuel therein relatively constant incident to changes in the volume of fuel in said accumulator, a fuel pump in said housing comprising a piston adapted to be mechanically driven by said engine in direct relation to the speed of rotation thereof for pressurizing fuel in said accumulator, a fuel injection nozzle communicating with said accumulator and the combustion chamber of said diesel internal combustion engine, a fluid flow control valve mechanically and functionally independent from said fuel pump and having fluid flow control ports communicating directly with said accumulator and said injection nozzle for controlling the flow of fuel from said accumulator to said injection nozzle, said valve being movable between an open and closed position independently of the pressure of the fuel in said accumulator, an electric solenoid for control-ling movement of said valve independently of the pressure of the fuel in said accumulator, and means for energizing said solenoid independently of said fuel pump and pressure in said accumulator in response to selected engine and environmental parameters.

2. A fuel injector in accordance with claim 1, wherein the frequency of operation of said fuel pump is independent of the frequency of operation of said solenoid.

3. A fuel injection system in accordance with claim 1, wherein said valve comprises a sleeve valve having radially disposed ports.

4. An electric non-fuel pressure responsive fuel injector system for a diesel internal combustion engine comprising an injector housing adapted to be mounted in the space and position of a conventional pressure excited fuel injector in direct communicating relationship with the combustion chamber of said diesel internal combustion engine, a fuel accumulator including means for maintaining the pressure of liquid fuel therein relatively constant incident to changes in the volume of fuel in said accumulator, a fuel pump in said housing comprising a piston adapted to be mechanically driven directly by said engine in direct relation to the speed of rotation thereof for pressurizing fuel in said accumulator, a fuel injection nozzle communicating with said accumulator and the combustion chamber of said diesel internal combustion engine, a fluid flow control sleeve valve mechanically and functionally independent from said fuel pump and having radially directed fuel flow control ports communicating with said accumulator and said injection nozzle for controlling the flow of fuel from said accumulator to said injection nozzle, said fuel ports being oriented relative to the direction of opening and closing of said sleeve valve whereby the pressure of fuel passing therethrough exerts no opening or closing force on said valve, an electric solenoid for controlling movement of said valve independently of the pressure of the fuel in said accumul-ator and of the speed of rotation of said engine, and means for energizing said solenoid independently of said fuel pump and pressure in said accumulator in response to selected engine and environmental parameters.