CA1287533C - Delivery of metered quantities of fuel to an engine - Google Patents
Delivery of metered quantities of fuel to an engineInfo
- Publication number
- CA1287533C CA1287533C CA000489636A CA489636A CA1287533C CA 1287533 C CA1287533 C CA 1287533C CA 000489636 A CA000489636 A CA 000489636A CA 489636 A CA489636 A CA 489636A CA 1287533 C CA1287533 C CA 1287533C
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- chamber
- engine
- gas
- metered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
- F02M69/08—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by the fuel being carried by compressed air into main stream of combustion-air
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
- F02D41/38—Controlling fuel injection of the high pressure type
- F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
- F02M69/002—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for intermittently metering the portion of fuel injected
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/02—Engines characterised by their cycles, e.g. six-stroke
- F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
- F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2400/00—Control systems adapted for specific engine types; Special features of engine control systems not otherwise provided for; Power supply, connectors or cabling for engine control systems
- F02D2400/04—Two-stroke combustion engines with electronic control
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Abstract
ABSTRACT
A method of delivering a metered quantity of fuel to an internal combustion engine is described. Fuel is metered in a chamber, which may be in the form of a conduit, the metered quantity varying in size in accordance with engine load. A pulse of gas such as air is admitted to the chamber to displace the fuel from the chamber and deliver it through a nozzle to the engine. The quantity and/or the length of time that the gas is admitted to the chamber is varied with variations in the metered quantity of fuel.
A method of delivering a metered quantity of fuel to an internal combustion engine is described. Fuel is metered in a chamber, which may be in the form of a conduit, the metered quantity varying in size in accordance with engine load. A pulse of gas such as air is admitted to the chamber to displace the fuel from the chamber and deliver it through a nozzle to the engine. The quantity and/or the length of time that the gas is admitted to the chamber is varied with variations in the metered quantity of fuel.
Description
` ~ ~Z8~
DELIVERY OF METERED_QUANTITIES OF FUEL TO AN ENGINE
This invention is directed to the metering and delivery of fuel to an internal combustion engine, and in particular concerns those systems employing a pulse o~ gas to deliver and/or inject a metered quantity of uel. The invention has particular applicability to the fueling of engines for transport vehicles, which may experience frequent and substantial transient load conditions.
There is an increasing requirement for less expen-sive, and more fuel efficient, fuel injection systems forinternal combustion engines. Conventional fuel injection systems have previously required a high pressure fuel pump, and high differential pressure metering apparatus, in order to achieve an acceptable degree of fuel atomisation and hot fuel handling ability. Both these requirements result in a high cost of componentry due to the high standard of engineering required in production, the close tolerances on manufacturing dimensions, and use of expensive materials of construction.
The use of pneumatic fuel metering was described in the SAE technical paper 820351 by Mackay, and further ~ ` details may be found in United Kingdom Patent Nos. 2,018,906 - and 2,102,50I and Canadian Patent Nos. 1,183,048 and 1,187,355. Such u~e significantly alleviates the problems deacribed a~ove.
In the methods of pneumatic fuel metering and injection described~in the above documents, a metered quantity of fuel located in a chamber is expelled from that chamber by a pulse of gas at high pressure for delivery to the engine. Such delivery is preferably via fle~ible tubing to the engine's inlet manifold but may alternatively be delivered directly into the combustion chamber. Existing systems operate by providing gas at an elevated pressure upstream of a valve at the gas inlet port of the chamber, and opening that;valve in response to instruction from a programmed electronic controller. The period of valve opening has previously been maintained constant for all metered quan- l '. .
:
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, . , : . .. : - . . . , . : , ,. , : , , . , , ., . :, ~ , . . .
- i. . . . . , . . . :
~lZ87~33 tities of fuel to be delivered from the chamber by the gas pulse, the system being designed so the period is sufficient to deliver the required metered quantity of fuel at maximum fuel demand of the e~gine. The period of valve opening was controlled by a constant width pulse from the electronic controller.
However, for acceptable operation of a given engine, the system must be able to handle a wide range of fuel quantities. Under steady state operation (i.e. constant speed and load) a fuel metering and delivery system requires a turn-down ratio of about 5 to 1, but on abrupt load increases the engine can require, for a very short period, up to twice as much fuel than that at wide open throttle.
Current evidence suggests that although a constant gas pulse width is sufficient to expel the required amount of fuel from the chamber, the quantity of air actually delivered with the metered quantity of fuel significantly decreases with increased metered fuel quantities. This decrease in air quantity is thought to be due to inertia and viscosity~effects of the increased quantity of fuel, and has a detrimental effect on the~quantity of fuel actually delivered,;the~quality ~of~the fuel air mixture preparation and~spray~ pattern delivered to the engine.
~ t is thè~object~of the present invent~ion to provide`;a~meth~od of delivering fuel to an engine by the use of a compres~se~d ga;s~ which will~give~improved engine response in transient~ load conditions.~
The~present invention proposes a method of deliver- -ing~fuel to~an~engine;by the~;a;dmission~of compressed gas to 30 a chamber~to~displace~a metered~quantity of fuel~therefrom, ~and~var~ying~the~mass~of gas admitted with variations in the fuel d~emand~so that~as~the fuel demand increases the mass of ~gas~increases.~
The~increaslng of~the`~mass of gas admitted to the 3;5 ~chambe~r~to~di~sp~lace~the~metered quantity of fuel, as the quant~ity~of fuel increases~, results in additional energy per ùnit~weight af~foe~ `be~ing~ava~ilable~to~displace the fuel ~
from~the~metering~chamber;and~transport the fuel to and ~:
:,: ' '.-.' : : ' .. ' ! ' . ' , 12~S33 through the injection nozzle.
Also the increased mass of gas will assis~ in the atomisation and spray forma~ion of the fuel issuing from the nozæle. Subject to the degree of increase in the gas mass relative to the fuel quantity, the specific energy remaining in the gas at the nozzle may also increase with the increase in fuel quantity, and if not increased should at least be maintained substantially constant for the major part o the range of fuel quantities within normal operating conditions.
The variation of the gas mass may be in accordance with a linear relation to the variation in fuel quantity, or any other selected relation.
The mass of gas delivered to the metering chamber is influenced by the pressure and temperature of the gas at entry to the metering chamber. However, from practical consi-derations it is not convenient to vary either the pressure or temperature, particularly having regard to the requirement of effecting~the variation in a time interval of a few milli-seconds. The~most convenient means of varying the mass of gas lS to vary the time period during which the gas is admitted~to the~metering;chamber.
More speclficaily there is provided~a method of dellvering fuel to~an~engine comprising establishing a ~ -meterèd quantity of~fuel in a chamber, said chamber having ' 25 à gas,supply:po~rt~and~a fuel delivery port, and displacing~ , the~fuel from~s~aid~chamber through said fuel delivery port ,' and~delivérlng~the~fuel~through~a nozzle~ to the engine, said ~` displacement~and deliv~ery of the ~fuel being effected by ~admlsslon~of~gas~to~the chamber thro~ugh said gas supply ~- ' 30 ~ port,,~wherein~the~,mass of gas~admi~tted~is varied in accord-~ance~wlth~the~fùel;demand of said~engine;.
As~i~s known, when a~fluid~and particularly a liquid ~ flows~through~a~;~condult~a;~layer of~the liquid is formed on ; ` ~the~ internàl-surface of the~conduit. The thickness of the 35 ~ ayer ls dé~pendent on~a~numbe~r of facto~rs including the vis~cos~i~,ty~of~ the~ iquld, the~ vel~ocity of flow, and the `~ -surface~f~inish~of~the conduit. As the velocity of the liquid ~-decreasës'the-~thlckness'of'~the~layer increases, and thus in ~'., ~' ~' . ' ; , '.. ' ' i . ' ' ' ' ' ' ' "
~Z8~S33 -- 5 ~
the fuel metering systems of the type under consideration, if the velocity of the fue]. delivery decreases the quantity of fuel in the stationary layer increases.
It is therefore seen that if there is an increase in the fuel quantity without a corresponding increase in the gas mass propelling the fuel, a portion of the increase in fuel quantity may not be delivered to the engine, but is consumed in increasing the stationary layer. Accordingly, by increasing the mass of air propelling the fuel as the fuel quantity is increased, a decrease in fuel velocity may be avoided and the thickness of the stationary layer remains substantially constant.
It is possible to reduce the thickness of the layer if the increase in the air mass i5 sufficient to increase the velocity of the fuel. This can be beneficial in two ways. Increasing the gas mass without an increase in the metered quantity of fuel will increase the fuel velocity and consequently reduce the layer thickness. In this~way a limited increase in fuel quantity delivered to the nozzle can be achieved~without changing the actual metered quantity. This~ manner of increasing fuel supply to the engine can be~useful where the fuel demand increase is relatlvely~small and of short duration.
Sècondly, if the increase in the gas mass is asso-25 ciated with an~lncrease in~metered quantlty of~fuel, and is -sufficient to increase~the overall fuel velocity, then a reductlon~;of;the fuel layer thlckness may result, thus further increasing the~quantity of fuel~delivered through the~nozzle.`This may be used to~advantage when there is a large~or~rapid inc~reasé~;in the fuel demand.
The~quantity of fuel may be metered upon introduc-tion~to~the;~chamber,~;or may be metered by and/or during the c~ourse~of~ th~e~admlss~lon of~gas to the chamber.
T~he~invention may be more readily understood from 35~ ;the~followi~ng~;exàmples, illustrated by the accompanying drawings,;~of practlcal~arrangements of metering and injecting fuel~ ;In~thê drawings "~
Figure 1 shows a fuel metering apparatus for use in the present invention.
Figure 2 shows a sectional view along 2-2 in Figure - 1, with the addition of fur~her metered fuel delivery appara-tus.
Figure 3 is a logic diagram of the operation of an electronic controller to regulate the mass of gas available to deliver the fuel.
Figure 4 is a diagram illustrating the variation in the period of gas admission with fuel demand.
Figures 5a to 5d inclusive illustrate variations to fuel quantity delivered in relation to gas mass.
With respect to Figures 1 and 2, the metering apparatus shown comprises a body 110, having incorporated therein four individual metering units 111 arranged in side by side relationship. This apparatus is thus suitable for use with a four cylinder engine, with each metering unit 111 dedicated to a separate cylinder. The nipples 112 and 113 are adapted for connection to a fuel supply line and a fuel -~
return line respectively (not shown), and communicate with respective fuel supply and return galleries 60 and 70 ~` provided within the body llO for the supply and return of fuel from~each of the metering units lll ~Each metering unit 111 is provided with an indivi-dual fuel~delivery~nipple 114 to which is connected a respec-~tive metered~fuel~delivery conduit 108 which conducts theindividually metered~quantities of fuel to an injector nozzle 18 (Flgure 2). The n~ozzle is located at a suitable position to deliver the fuel~to the engine, such as inserted in the inlet~manifold of the engine near the respective cylinder : air~inlet valve. Further details of the apparatus are given in~our~abovementioned Canadian Pa~ent No. 1,183,048.
~ The body~llO is preferably positioned close to the inj~ector~nozzle 18,~and the metered fuel delivery conduits ; ~108~arè~suitable tubing of approximately 1.8mm diameter, and from lO~to 40~cm in length varying with the distance to each ` cylinder. ~ ~ ~
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~ 7~3 Figure 2 shows in section one metering unit 111 having a metering rod 115 extending into both the air supply chamber 119 and metering chamber 120. Each of the our meter-ing rods 115 pass through the common leakage collection chamber 116, which is formed by a cavity provided in the body 110 and the coverplate 121 attached in sealed relation to the body 110. The function and operation o the leakage collection chamber 116 is no part of this invention and is described in greater detail in the abovementioned Canadian Patent No. 1,183,048.
Each metering rod 115 is hollow, and is axially slidable in the body 110, the extent of projection of the metering rod into the metering chamber 120 being varied to adjust the quantity of fuel displaceble from the metering chamber 120. The valve 143, at that end of the metering rod located in the metering chamber 120, is supported by the rod 143a and normally held closed by the spring 145, located between the upper end of the hollow rod 115 and valve rod .--143a. The flow of air through the hollow bore of the metering rod 115 from the air supply chamber 119 to the metering chamber 120 is controlled by the valve 143. Upon the pressure -in the air supply chamber:ll9 rising to a predetermined value :
the valve 143 is opened to permit air to flow from air supply chamber 119 to the metering chamber 120 through hollow rod 115, to displace the fuel from the metering chamber 120.
The quantity of fuel displaced by the air is that -fuel located in the metering chamber 120 between the point of entry of the air to the metering chamber, and the point of discharge of fuel between the air admission valve 143 and 3~ the delivery valve 109 at the opposite end of the metering chamber 120.
~ Each of the metering rods 115 are coupled to the crosshead 161, and the crosshead is coupled to the actuator rod ~l60 which is slidably supported in the body 110. The ac:tuator:rod 160 is:coupled to the motor 169, which is controlled in response to the engine fuel demand, to adjust the extent of projection of the metering rods 115 into the ` metering chambers 120, and hence the position of the air ;::
admission valves: 143 so, the metered quantity of fuel ~:~
: . i , . . . . . .
., . ., ; .;., . ;' : ' ., ' ' , '', ' ~ , ' ' -:' ' .', 1~75~3 delivered by the admission of the air is in accordance with the fuel demand. The motor 169 may be a reversible linear type stepper motor such as the 92100 series marketed by Airpax Corp.
S The fuel. delivery valves 109 are each pressure actuated to open in response to the pressure in the metering chamber 120, when the air is admitted thereto from the air supply chamber 119. Upon the air entering the metering chamber 120 through the valve 143, the delivery valve 109 also opens, and the air will move towards the delivery valve displacing fuel from the metering chamber through the delivery valve. The air admission valve 143 is maintained open until suficient air has been supplied to displace the fuel between the valve 143 and 109 from the chamber, an-d to provide additional air to transfer the fuel through the conduit 108 to the nozzle 18, and to atomisation the fuel as it is delivered through the nozzle.
: Each metering chamber 120 has a respective fuel inlét port 125 and a fuel outlet port 126 controlled by res- -pec:tive valves 127 and 128~to permit circulation of fuel from the~inlet~gallery~60, through the:metering chamber 120, to the outlet~gallery 7;0.~Each of the valves 127 and 128 are ~;` connected~to~the~respective diaphragms 129 and 130. The ~ ~valves~:~12~7;~and:12~8:are spring-lo~aded to an open position, `~ 25 and~are~clo~se~in~response~:to the application of air under . ~ pressure to~t:he:respect~ive~di~aphragms 129 and 130 via the dl~aphr~agm~cavl~tl:es~ 31~and~i32. E~ach of;the~diaphragm cavi-ties~;~are~:in~constant communication with the air conduit 133, `~
~ and~the~;~:conduit 133~is in constant communication with the : : 30~a}r s`upply~cha~mber~119~by ~the~c~ondul:t~135~.
Thus~ when~alr und`er pressure is admitted to the .ai:r~supply:chamber~:ll9:and hence to the metering chamber 120 ~to:~effect~de~livery of fuel, the air als~ acts:on the diaphràgms~129~ ànd.~130~to~cause the:valves 127 and 128 to 35~clos~e the~:fusl~inl5t~and outl-r: p,rts ;1~5 and~126.
:. . :: . : : : . , . , : .
~2~ii33 The control of the supply of air to the chamber 119 through conduit 135, and to the diaphragm cavities 131 and 132 through conduit 133, is regulated in time relation with the cycling of the engine by the solenoid operated valve 150. The common air supply conduit 151, connectable to a compressed air supply via nipple 153, runs through the body 110 with respective branches 152 providing air to the respec-tive solenoid valve 150 of each metering unit 111.
Normally the spherical valve element 159 is posi-tioned, under action from springs 170, to prevent the flowof air from conduit 151 to conduit 135, and to vent conduit 135 to atmospheric via vent port 161. When the solenoid is energised the force of the spring 170 acting on the valve element 159 is relieved, and the valve element is displaced by the pressure on the air supply to permit air to flow from conduit 151 to conduits 135 and 133.
The timing of the energizing of the solenoid 150 in relation to the engine cycle may be controlled by a suit-able sensing device 171, activated by a rotating component of the engine, such as the crankshaft or flywheel 172 or any other component driven at a speed directly related to engine speed.~A sensor~suitable for t~his purpose is an optical switch including an infra-red source and a photo detector with Schmitt trigger.
~ Previously it has been proposed that the duration of energization of the solenoid 150 be a fixed period, independent of~fuel quantity to be delivered and engine speed. This fixed period was selected to suit the maximum fuel~demand when the engine is operating at maximum engine 30 ;speed.~
The most convenient manner of controlling the ~operation of the~solenoid 150 is an electronic controller, ~which~provides~a~pulse~of electrical energy of fixed duration to~the~solenoid~l~rrespective of the engine fueling require-35~ments.~ However, in using that form control in practice, ithas~-;been~found that the~actual quantity of air passed with `~the~fuel thr~ough~the~lnjector nozzle 18 per fuel delivery :
tends to reduce with increasing fuel delivery levels.
This is believed to be due to changes in inertia and viscosity effects arising with the increased fuel level.
This can be compensated for by the present invention by increasing the length of time the electrical energy is applied to the solenoid 150 at the higher fuelling levels, thus increasing the time during which gas enters the meter-ing chamber 120 and so increasing the mass of air available to pass along the fuel conduit and through the delivery nozzle.
Figure 3 is a logic diagram representing a typical mode of operation of the electronic controller 192 (Figure 1) to effect variation of the period that the solenoid 150 is energised in proportion to the metered quantity of fuel to be delivered to meet the engine fuel demand. The control-ler 192 is programmed with the required relationship between metered fuel quant~lty and air mass per injection cycle.
As sh~own in Figure~l the actuator rod 160 carries a wiper arm I90 which co-operates with a stationary resis-tance strip l91 mounted in the body 110. The wiper and resis-- tance~strip forming a feed back potentiometer 198~ The ~a~ctuator~`rod 160~ls coupl~ed~to the metering~rods 111 and varies~the extent~of~projection of the metering rods into the metering chambers 120, and hence varies the metered ~5 quantity~of~fue;1;dell~vered~.~;Accordingly;the; position of the wipe~r arm 190 on the resistance strip l91 and hence the out-put~of~the~`fee~d-ba~ck~potentlometer is dlrectly proportional ~to the~metered~quantlty of uèl~ belng delivered.
The~electronic con~roller 192 is programmed to 30 ~recelve~at~a~regul;ar lnte~rval~of voltage reading from the p`ot~ent~iometer~198~and~thereby determine the position of the ~actuator~rod 160 and~hence the size of the metered quantity of fuêl,;~The readings~from ~the ~resistor are conveniently made`~a~t~hal~ milli-second intervals.
35~ R~e~ferring~still t~o Figure 3, having received the voltage~r~eading~from~the~potentiometer the controller 192 ~8~S3~
determines the period of energization of the solenoid 150 required for the metered quantity of fuel corresponding to the position of the actuator rod 160, If at the time of the controller making the deterrnination the engine is in that S part of the engine cycle when fuel is being delivered, then the controller will make an adjustment to the rernaining period of energization. If as a result of this adjustment the period of energization is reduced to zero, then the controller will switch off the solenoid energizing channel so that delivery of fuel and gas will cease. However, if the remaining period is not reduced to zero then the solenoid will continue to be energized and fuel and gas will continue to be delivered. At the next half milli-second period the sequence is~repeated.
Reverting to the determination of the period of ; energizing of~the solenoid, if at that time the engine is -~ not in that part of its cycle when fuel is to be delivered, ` the~newly determined period of energization is stored. If within the then current half milli-second interval the :
engine`enters thé~part of its cycle when fuel is to be , delivered,~then the so~lenoid will be energized for the newly determlne'd`period.~In~the~event that the engine does not ~enter th~e~part of its cycl~e for the delivery of fuel during the~half~milli-second~interval, then at the end of that peri~od;the`~sequence~is~repeated~as~above explained.
Comme~rcial~l~y~avallable componentry can be arranged and~programm'ed~to~per,form~the,;~functions requi;red to fulfill the;~above~discussed logic d'iagram. Also,other factors may be~introduced~t~o~vary~the~period~that the solenoid is ~O:~energized~ In~automotlve~applications one factor that may be~
taken~lnto~ac~count,;ls~the~`voltage of the electrical energy source~to~operat~e~the~solenoid.
T~he~voltage o~f~the~battery~provided ln an auto~
mobile~m'ay~ vary~signi~fi'cant~ly;~under operating conditions ~~
3~5 -~fr~`'m=the~nomi;nal~ rated~ 2~volts~. Slgnificant drop in voltage ,can~occur~a~t~times~when~high `loads are applied to the ~ ~`
. ~ : . . . ; . . : . . . .
lZ~7S33 battery, such as cranking the engine during start-up. In order to compensate for this drop in voltage available to energize the solenoid, the period of energization may be extended.
The electronic controller 192 may thus incorporate a function to compare the actual voltage available to the solenoid against the battery rated voltage and if the actual voltage is below rated, an extension of the period of energization of the solenoid may be made. The degree of extension of the period relative to the drop in voltage may be pre-programmed into the electronic cont~oller.
The period of energization of the solenoid may be expressed by the formula p~ ~ = PWo ~ PWbv + PWACT
~ Where PWe is actual period of energization , ' PW is a basic period of energization o PWbv is battery voltage compensation ,, . ~ period ~ ~ PWAcT is actuator rod position compensa- -tion period Typlcally~PWO is the period of energization at no-load on the`engine and may~be of the order of 12 to 15 milli-" ~seconds,~and the~maximum increase ln response to the actua-tlon~rod~position~may be~5~to~10 ml11i-seconds, the increase belng~linear;over~the range of movement of the actuator rod.
The~increase~in~energiza~tion~period~for decline in battery voltàgè~may~;be of~the~;~o~rder of 0.~5~mi11i-seconds per~volt.
~The~increase~of 5 to 10 mi11i-seconds~ for actuation rod ;~ ~ posltion~ls~fo~r ful]-~fuel~llng~under transient~load condition --~30 ~and~is~considerably~greater~ of the order of 50%) than that ~ ~ requi~red~under~fu;ll--open-throttle~steady conditions. The `~ ~ total time~p'er cyclé~that the~solenoid may be energised is of cour,s~e;'l'imi~ted~by~the~;cycle time of the engine and the tim~`required~t~o~fi~ the~met~ering chamber wlth fuel, the 35~ ;1atter~be~i;ng~of~the~order~of~8 milli-seconds.
It~is~des'irable from~combustion efficiency consi-`'`d~er~ion~for~'injection of the fuel to terminate at a fixedin'`th'e~engine cycle.~Acco~r~dlngly,~when the perlod oE
` ~337533 ~ 13 -energization of the solenoid is varied the termination point of the energization remains fixed and the additional time is obtained by advancing the initiation point of the ener-gization. Figure 4 of the drawings shows a typical variation in the duration of application of the air to the fuel being delivered in relation to the output of the potentiometer that is directly related to the quantity of fuel being delivered.
In the preceding description the period of energization of the solenoid has made the variable in response to variations in metered quantities of fuel. How-ever, it is to be understood that the purpose in varying that period is to achieve a corresponding variation in the mass of air available to effect the delivery of the metered quantity of fuel. As the pressure of the air supply is maintained constant by suitable pressure regulators, and in practical terms temperature variations normally encountered do not significantly influence the density of the air, the mass of air delivered to the metering chamber is directly related to the period that the air is available via the ; 20 solenoid valve 150.
~ When the englne is under transient conditions, requiring a~rapid increase in fuelling, it can be difficult to control-~a fuel metering and injection system to deliver thè optimum amount of fuel. From commencement of a transient the~first~one or two cycles of each cylinder should prefer-ably~havs~a higher~fuel loadlng than when operating at the same~throttle openlng~fo~r ste~ady state operation. This immed-`~ iate~enrichment~of~the fuel mixture is required to give the engine an acceptable rapid response when the throttle is suddenly~opened~. It has now been found that an acceptabletrans~ient~resp~onse can be obtained from an engine utilizing the~f`uel~me~tering~system~described above by increasing the ma;s~s;:of~the;~a~ir~availa~ble to deliver the fuel that is not :`
~`dependent~on~any~ increase in~the metered quantity of fuel.
35~ During~op~eration of an engine, the internal surfaces~of~the~fu~el delivery path, comprising delivery condult~108~ and~associated injector nozzle 18, remain wetted 12~7~ii3;~
by the ~uel after each delivery of fuel and air through the nozzle 18 to the engine. During substantially smooth engine operation (i.e. steady state or light acceleration or decele-ration) this residual wetting of the internal surfaces has no significant effect on the operation of the engine, as the amount of fuel retained by the wet surfaces remains substan-tially constant while the amount of air used for each delivery is constant.
Figure 5a illustrates the desired sequential fuel deliveries from the nozzle 18, for an engine transient requiring an immediate increase in fuel rate between deliver-ies 5 and 6. Figure 5b shows typical delivered fuel quanti-ties where the fuel metering and injection system is arranged so that each of the twelve deliveries of fuel are propelled by the same mass of air. The degree of residual wetting of delivery line 108 is increased for increased metered quanti-ties of fuel, and the amount of fuel delivered from the injector nozzle is seen to increase gradually between deliveries 5 and 9. From the first delivery at the new fuel metering rate, the amount of fuel delivered from nozzle 18 would be less than the metered quantity determined at the ` position of the metering rod 115 in the metering chamber 1~0, bècause the mass of air available cannot immediately handle the~increased quantity of fuel, and there is an increase in the residual wetness on the internal surfaces. However, the amount of fuel retained wettlng delivery line 108 is a func-tlon~both~of the ~quantlty~of fuel metered at the metering chamber,~and of the mass of the air used to deliver the - metered fuel along the conduit and out of the nozzle.
~Consider now Figure 5c where each delivery is ~ derived~from the same metered quantity~of fuel being in the `~ ~ metering chamber~l~20.~However, the mass of air for delivery 6~has~been made larger than the others, by energizing the s`olenoi~d~for a longer period. Delivery 6 ejects more fuel 3~5`~ from~the~nozzl~e 18 than de~livery 5, as it has reduced the quantity~of fuel wetting the inner surfaces o delivery line ; 108~ Furth~er, de~livery 7~passes correspondingly less fuel ~ : .
.
. - . : , ~ .. . :
.. .. : . . . :, . :: . .:
.,- , . . . .
.. -.. : , ~ . .. . ..
~ Z ~ 3 than delivery 5 as some fuel will be left in the delivery line 108 rewetting the surfaces. Subsequently delivery using the normal mass of air will deliver an amount of fuel from the nozzle corresponding to the metered quantity available in the metering chamber 120.
Referring now to Figure 5d, this illustrates a repeat of the engine transient conditions of Figure 5a except the system is now arranged so that the increased amount of fuel is propelled by an increased mass of air. Delivery 6, being the first delivery at the increased metered quantity of fuel and mass of air, will leave the delivery line 108 slightly less wet than the preceding delivery 5, while following pulses 7-8-9 etc., will maintain that reduced degree of~wetting. The effect on delivered fuel quantities can be seen in Figure 5d. The transient fuel enrichment is evident.~It will be appreciated that this arrangement ~provides also the desirable fuel enleanment on deceleration ~translents~due to the delivery line 108 entering a stage of lncreased residu~al~wetting. ~
~ T~he use of;the~capab;ility of reducing the wetness of the;internal surface~;of~the~fuel delivery conduit is prèferabl~y~in combination~with~the increase;in~metered quantit~y;~of fuel as; represented by~Figure~Sd,~ particularly when~the~e~ngine~ s~experienc~lng~a~severe transient condi-tion~ H~owe~ver,~eithe~r~ca`pabili~ty may~be used individually The~;ele~c~tronIc~c;ontroller~192; may~be ~arranged~to respond to a~t~ranslent~condltlon~s~ensed~by a~factor other~than the~
actuator~r`od~pos~it~ion~in~order;t~o~imp~lement~operation of the~
wetnes~s~reducti~on`~capabi~l~ity~,~such`as~by sensing the~rate of~ 0 ~ change~of~the~thrott1e~positlon.~
t~wl~ll however~be~appreciated that the invention de~scrlbed~ hereln~l~s~ not~restrlcte~d to the particular appa~ratus~déscribed~ n~detail~above, but is applicable to all~fuel meteri;ng~and/or~del~ivery~sys~tems utilizing a pulse of gas:to-propel a~metered~:quantlty of fuel for delivery to The metered t~uantity of fuel will depend on engine load, transient state, engine cylinder size, and selected operating air/fuel ratio, and may typically range from a few milligrams up to say 100 milligrams (or more) per injection.
Correspondingly, the preferred mass of air delivered to the metering chamber per injection may vary over the range 2 milligrams to 10 ~or more) miliigrams per injection. An approximate volumetric ratio of air to fuel measured at S.T.P. is 50:1. Air supply pressures are regulated but metering operation may be achieved typically using supply pressures over the range 200kPa to 1000kPa (or even higher).
Practically, the minimum pressure is determined by the need to operate valves, and to supply sufficient air mass, so that 400kPa is a more usual value. Similarly, maximum pressures tend to be determined according to the need for simple and efficient supply sources. In an automotive - application~a single~stage compressor would be desired, effectively limiting maximum pressures to around 800kPa.
~ ~Under some engine operating~conditions it may be desirable to lncre~ase the mass ~of alr per injection even though there is no corresponding increase in fuel quantity.
One~such condition~may be~during start-up of the engine particular~ly under cold start~conditions. The additional air will contr~ibute to improved atomization, particularly when 25 the~e`nglne is cold~and~vaporlzation i5 not~assisted by the ~i heat of the engine~
~ The~engine c~ondition in response to which the mass of air~is~varied may be timed from start-up so the air mass decreases~as the~time after start-up increases until the air~
30 ~mass;~fall;s~to~a predètermined;limit. ~If the engine condi-tion is~temperature~, again the air mass will decrease as the temperature increases until a predetermined limit is reached.
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, - : , , -.,
DELIVERY OF METERED_QUANTITIES OF FUEL TO AN ENGINE
This invention is directed to the metering and delivery of fuel to an internal combustion engine, and in particular concerns those systems employing a pulse o~ gas to deliver and/or inject a metered quantity of uel. The invention has particular applicability to the fueling of engines for transport vehicles, which may experience frequent and substantial transient load conditions.
There is an increasing requirement for less expen-sive, and more fuel efficient, fuel injection systems forinternal combustion engines. Conventional fuel injection systems have previously required a high pressure fuel pump, and high differential pressure metering apparatus, in order to achieve an acceptable degree of fuel atomisation and hot fuel handling ability. Both these requirements result in a high cost of componentry due to the high standard of engineering required in production, the close tolerances on manufacturing dimensions, and use of expensive materials of construction.
The use of pneumatic fuel metering was described in the SAE technical paper 820351 by Mackay, and further ~ ` details may be found in United Kingdom Patent Nos. 2,018,906 - and 2,102,50I and Canadian Patent Nos. 1,183,048 and 1,187,355. Such u~e significantly alleviates the problems deacribed a~ove.
In the methods of pneumatic fuel metering and injection described~in the above documents, a metered quantity of fuel located in a chamber is expelled from that chamber by a pulse of gas at high pressure for delivery to the engine. Such delivery is preferably via fle~ible tubing to the engine's inlet manifold but may alternatively be delivered directly into the combustion chamber. Existing systems operate by providing gas at an elevated pressure upstream of a valve at the gas inlet port of the chamber, and opening that;valve in response to instruction from a programmed electronic controller. The period of valve opening has previously been maintained constant for all metered quan- l '. .
:
~.,;~, X
, . , : . .. : - . . . , . : , ,. , : , , . , , ., . :, ~ , . . .
- i. . . . . , . . . :
~lZ87~33 tities of fuel to be delivered from the chamber by the gas pulse, the system being designed so the period is sufficient to deliver the required metered quantity of fuel at maximum fuel demand of the e~gine. The period of valve opening was controlled by a constant width pulse from the electronic controller.
However, for acceptable operation of a given engine, the system must be able to handle a wide range of fuel quantities. Under steady state operation (i.e. constant speed and load) a fuel metering and delivery system requires a turn-down ratio of about 5 to 1, but on abrupt load increases the engine can require, for a very short period, up to twice as much fuel than that at wide open throttle.
Current evidence suggests that although a constant gas pulse width is sufficient to expel the required amount of fuel from the chamber, the quantity of air actually delivered with the metered quantity of fuel significantly decreases with increased metered fuel quantities. This decrease in air quantity is thought to be due to inertia and viscosity~effects of the increased quantity of fuel, and has a detrimental effect on the~quantity of fuel actually delivered,;the~quality ~of~the fuel air mixture preparation and~spray~ pattern delivered to the engine.
~ t is thè~object~of the present invent~ion to provide`;a~meth~od of delivering fuel to an engine by the use of a compres~se~d ga;s~ which will~give~improved engine response in transient~ load conditions.~
The~present invention proposes a method of deliver- -ing~fuel to~an~engine;by the~;a;dmission~of compressed gas to 30 a chamber~to~displace~a metered~quantity of fuel~therefrom, ~and~var~ying~the~mass~of gas admitted with variations in the fuel d~emand~so that~as~the fuel demand increases the mass of ~gas~increases.~
The~increaslng of~the`~mass of gas admitted to the 3;5 ~chambe~r~to~di~sp~lace~the~metered quantity of fuel, as the quant~ity~of fuel increases~, results in additional energy per ùnit~weight af~foe~ `be~ing~ava~ilable~to~displace the fuel ~
from~the~metering~chamber;and~transport the fuel to and ~:
:,: ' '.-.' : : ' .. ' ! ' . ' , 12~S33 through the injection nozzle.
Also the increased mass of gas will assis~ in the atomisation and spray forma~ion of the fuel issuing from the nozæle. Subject to the degree of increase in the gas mass relative to the fuel quantity, the specific energy remaining in the gas at the nozzle may also increase with the increase in fuel quantity, and if not increased should at least be maintained substantially constant for the major part o the range of fuel quantities within normal operating conditions.
The variation of the gas mass may be in accordance with a linear relation to the variation in fuel quantity, or any other selected relation.
The mass of gas delivered to the metering chamber is influenced by the pressure and temperature of the gas at entry to the metering chamber. However, from practical consi-derations it is not convenient to vary either the pressure or temperature, particularly having regard to the requirement of effecting~the variation in a time interval of a few milli-seconds. The~most convenient means of varying the mass of gas lS to vary the time period during which the gas is admitted~to the~metering;chamber.
More speclficaily there is provided~a method of dellvering fuel to~an~engine comprising establishing a ~ -meterèd quantity of~fuel in a chamber, said chamber having ' 25 à gas,supply:po~rt~and~a fuel delivery port, and displacing~ , the~fuel from~s~aid~chamber through said fuel delivery port ,' and~delivérlng~the~fuel~through~a nozzle~ to the engine, said ~` displacement~and deliv~ery of the ~fuel being effected by ~admlsslon~of~gas~to~the chamber thro~ugh said gas supply ~- ' 30 ~ port,,~wherein~the~,mass of gas~admi~tted~is varied in accord-~ance~wlth~the~fùel;demand of said~engine;.
As~i~s known, when a~fluid~and particularly a liquid ~ flows~through~a~;~condult~a;~layer of~the liquid is formed on ; ` ~the~ internàl-surface of the~conduit. The thickness of the 35 ~ ayer ls dé~pendent on~a~numbe~r of facto~rs including the vis~cos~i~,ty~of~ the~ iquld, the~ vel~ocity of flow, and the `~ -surface~f~inish~of~the conduit. As the velocity of the liquid ~-decreasës'the-~thlckness'of'~the~layer increases, and thus in ~'., ~' ~' . ' ; , '.. ' ' i . ' ' ' ' ' ' ' "
~Z8~S33 -- 5 ~
the fuel metering systems of the type under consideration, if the velocity of the fue]. delivery decreases the quantity of fuel in the stationary layer increases.
It is therefore seen that if there is an increase in the fuel quantity without a corresponding increase in the gas mass propelling the fuel, a portion of the increase in fuel quantity may not be delivered to the engine, but is consumed in increasing the stationary layer. Accordingly, by increasing the mass of air propelling the fuel as the fuel quantity is increased, a decrease in fuel velocity may be avoided and the thickness of the stationary layer remains substantially constant.
It is possible to reduce the thickness of the layer if the increase in the air mass i5 sufficient to increase the velocity of the fuel. This can be beneficial in two ways. Increasing the gas mass without an increase in the metered quantity of fuel will increase the fuel velocity and consequently reduce the layer thickness. In this~way a limited increase in fuel quantity delivered to the nozzle can be achieved~without changing the actual metered quantity. This~ manner of increasing fuel supply to the engine can be~useful where the fuel demand increase is relatlvely~small and of short duration.
Sècondly, if the increase in the gas mass is asso-25 ciated with an~lncrease in~metered quantlty of~fuel, and is -sufficient to increase~the overall fuel velocity, then a reductlon~;of;the fuel layer thlckness may result, thus further increasing the~quantity of fuel~delivered through the~nozzle.`This may be used to~advantage when there is a large~or~rapid inc~reasé~;in the fuel demand.
The~quantity of fuel may be metered upon introduc-tion~to~the;~chamber,~;or may be metered by and/or during the c~ourse~of~ th~e~admlss~lon of~gas to the chamber.
T~he~invention may be more readily understood from 35~ ;the~followi~ng~;exàmples, illustrated by the accompanying drawings,;~of practlcal~arrangements of metering and injecting fuel~ ;In~thê drawings "~
Figure 1 shows a fuel metering apparatus for use in the present invention.
Figure 2 shows a sectional view along 2-2 in Figure - 1, with the addition of fur~her metered fuel delivery appara-tus.
Figure 3 is a logic diagram of the operation of an electronic controller to regulate the mass of gas available to deliver the fuel.
Figure 4 is a diagram illustrating the variation in the period of gas admission with fuel demand.
Figures 5a to 5d inclusive illustrate variations to fuel quantity delivered in relation to gas mass.
With respect to Figures 1 and 2, the metering apparatus shown comprises a body 110, having incorporated therein four individual metering units 111 arranged in side by side relationship. This apparatus is thus suitable for use with a four cylinder engine, with each metering unit 111 dedicated to a separate cylinder. The nipples 112 and 113 are adapted for connection to a fuel supply line and a fuel -~
return line respectively (not shown), and communicate with respective fuel supply and return galleries 60 and 70 ~` provided within the body llO for the supply and return of fuel from~each of the metering units lll ~Each metering unit 111 is provided with an indivi-dual fuel~delivery~nipple 114 to which is connected a respec-~tive metered~fuel~delivery conduit 108 which conducts theindividually metered~quantities of fuel to an injector nozzle 18 (Flgure 2). The n~ozzle is located at a suitable position to deliver the fuel~to the engine, such as inserted in the inlet~manifold of the engine near the respective cylinder : air~inlet valve. Further details of the apparatus are given in~our~abovementioned Canadian Pa~ent No. 1,183,048.
~ The body~llO is preferably positioned close to the inj~ector~nozzle 18,~and the metered fuel delivery conduits ; ~108~arè~suitable tubing of approximately 1.8mm diameter, and from lO~to 40~cm in length varying with the distance to each ` cylinder. ~ ~ ~
-.,~ ,: . . : ., , : ,. ............ . .......... . .
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~ 7~3 Figure 2 shows in section one metering unit 111 having a metering rod 115 extending into both the air supply chamber 119 and metering chamber 120. Each of the our meter-ing rods 115 pass through the common leakage collection chamber 116, which is formed by a cavity provided in the body 110 and the coverplate 121 attached in sealed relation to the body 110. The function and operation o the leakage collection chamber 116 is no part of this invention and is described in greater detail in the abovementioned Canadian Patent No. 1,183,048.
Each metering rod 115 is hollow, and is axially slidable in the body 110, the extent of projection of the metering rod into the metering chamber 120 being varied to adjust the quantity of fuel displaceble from the metering chamber 120. The valve 143, at that end of the metering rod located in the metering chamber 120, is supported by the rod 143a and normally held closed by the spring 145, located between the upper end of the hollow rod 115 and valve rod .--143a. The flow of air through the hollow bore of the metering rod 115 from the air supply chamber 119 to the metering chamber 120 is controlled by the valve 143. Upon the pressure -in the air supply chamber:ll9 rising to a predetermined value :
the valve 143 is opened to permit air to flow from air supply chamber 119 to the metering chamber 120 through hollow rod 115, to displace the fuel from the metering chamber 120.
The quantity of fuel displaced by the air is that -fuel located in the metering chamber 120 between the point of entry of the air to the metering chamber, and the point of discharge of fuel between the air admission valve 143 and 3~ the delivery valve 109 at the opposite end of the metering chamber 120.
~ Each of the metering rods 115 are coupled to the crosshead 161, and the crosshead is coupled to the actuator rod ~l60 which is slidably supported in the body 110. The ac:tuator:rod 160 is:coupled to the motor 169, which is controlled in response to the engine fuel demand, to adjust the extent of projection of the metering rods 115 into the ` metering chambers 120, and hence the position of the air ;::
admission valves: 143 so, the metered quantity of fuel ~:~
: . i , . . . . . .
., . ., ; .;., . ;' : ' ., ' ' , '', ' ~ , ' ' -:' ' .', 1~75~3 delivered by the admission of the air is in accordance with the fuel demand. The motor 169 may be a reversible linear type stepper motor such as the 92100 series marketed by Airpax Corp.
S The fuel. delivery valves 109 are each pressure actuated to open in response to the pressure in the metering chamber 120, when the air is admitted thereto from the air supply chamber 119. Upon the air entering the metering chamber 120 through the valve 143, the delivery valve 109 also opens, and the air will move towards the delivery valve displacing fuel from the metering chamber through the delivery valve. The air admission valve 143 is maintained open until suficient air has been supplied to displace the fuel between the valve 143 and 109 from the chamber, an-d to provide additional air to transfer the fuel through the conduit 108 to the nozzle 18, and to atomisation the fuel as it is delivered through the nozzle.
: Each metering chamber 120 has a respective fuel inlét port 125 and a fuel outlet port 126 controlled by res- -pec:tive valves 127 and 128~to permit circulation of fuel from the~inlet~gallery~60, through the:metering chamber 120, to the outlet~gallery 7;0.~Each of the valves 127 and 128 are ~;` connected~to~the~respective diaphragms 129 and 130. The ~ ~valves~:~12~7;~and:12~8:are spring-lo~aded to an open position, `~ 25 and~are~clo~se~in~response~:to the application of air under . ~ pressure to~t:he:respect~ive~di~aphragms 129 and 130 via the dl~aphr~agm~cavl~tl:es~ 31~and~i32. E~ach of;the~diaphragm cavi-ties~;~are~:in~constant communication with the air conduit 133, `~
~ and~the~;~:conduit 133~is in constant communication with the : : 30~a}r s`upply~cha~mber~119~by ~the~c~ondul:t~135~.
Thus~ when~alr und`er pressure is admitted to the .ai:r~supply:chamber~:ll9:and hence to the metering chamber 120 ~to:~effect~de~livery of fuel, the air als~ acts:on the diaphràgms~129~ ànd.~130~to~cause the:valves 127 and 128 to 35~clos~e the~:fusl~inl5t~and outl-r: p,rts ;1~5 and~126.
:. . :: . : : : . , . , : .
~2~ii33 The control of the supply of air to the chamber 119 through conduit 135, and to the diaphragm cavities 131 and 132 through conduit 133, is regulated in time relation with the cycling of the engine by the solenoid operated valve 150. The common air supply conduit 151, connectable to a compressed air supply via nipple 153, runs through the body 110 with respective branches 152 providing air to the respec-tive solenoid valve 150 of each metering unit 111.
Normally the spherical valve element 159 is posi-tioned, under action from springs 170, to prevent the flowof air from conduit 151 to conduit 135, and to vent conduit 135 to atmospheric via vent port 161. When the solenoid is energised the force of the spring 170 acting on the valve element 159 is relieved, and the valve element is displaced by the pressure on the air supply to permit air to flow from conduit 151 to conduits 135 and 133.
The timing of the energizing of the solenoid 150 in relation to the engine cycle may be controlled by a suit-able sensing device 171, activated by a rotating component of the engine, such as the crankshaft or flywheel 172 or any other component driven at a speed directly related to engine speed.~A sensor~suitable for t~his purpose is an optical switch including an infra-red source and a photo detector with Schmitt trigger.
~ Previously it has been proposed that the duration of energization of the solenoid 150 be a fixed period, independent of~fuel quantity to be delivered and engine speed. This fixed period was selected to suit the maximum fuel~demand when the engine is operating at maximum engine 30 ;speed.~
The most convenient manner of controlling the ~operation of the~solenoid 150 is an electronic controller, ~which~provides~a~pulse~of electrical energy of fixed duration to~the~solenoid~l~rrespective of the engine fueling require-35~ments.~ However, in using that form control in practice, ithas~-;been~found that the~actual quantity of air passed with `~the~fuel thr~ough~the~lnjector nozzle 18 per fuel delivery :
tends to reduce with increasing fuel delivery levels.
This is believed to be due to changes in inertia and viscosity effects arising with the increased fuel level.
This can be compensated for by the present invention by increasing the length of time the electrical energy is applied to the solenoid 150 at the higher fuelling levels, thus increasing the time during which gas enters the meter-ing chamber 120 and so increasing the mass of air available to pass along the fuel conduit and through the delivery nozzle.
Figure 3 is a logic diagram representing a typical mode of operation of the electronic controller 192 (Figure 1) to effect variation of the period that the solenoid 150 is energised in proportion to the metered quantity of fuel to be delivered to meet the engine fuel demand. The control-ler 192 is programmed with the required relationship between metered fuel quant~lty and air mass per injection cycle.
As sh~own in Figure~l the actuator rod 160 carries a wiper arm I90 which co-operates with a stationary resis-tance strip l91 mounted in the body 110. The wiper and resis-- tance~strip forming a feed back potentiometer 198~ The ~a~ctuator~`rod 160~ls coupl~ed~to the metering~rods 111 and varies~the extent~of~projection of the metering rods into the metering chambers 120, and hence varies the metered ~5 quantity~of~fue;1;dell~vered~.~;Accordingly;the; position of the wipe~r arm 190 on the resistance strip l91 and hence the out-put~of~the~`fee~d-ba~ck~potentlometer is dlrectly proportional ~to the~metered~quantlty of uèl~ belng delivered.
The~electronic con~roller 192 is programmed to 30 ~recelve~at~a~regul;ar lnte~rval~of voltage reading from the p`ot~ent~iometer~198~and~thereby determine the position of the ~actuator~rod 160 and~hence the size of the metered quantity of fuêl,;~The readings~from ~the ~resistor are conveniently made`~a~t~hal~ milli-second intervals.
35~ R~e~ferring~still t~o Figure 3, having received the voltage~r~eading~from~the~potentiometer the controller 192 ~8~S3~
determines the period of energization of the solenoid 150 required for the metered quantity of fuel corresponding to the position of the actuator rod 160, If at the time of the controller making the deterrnination the engine is in that S part of the engine cycle when fuel is being delivered, then the controller will make an adjustment to the rernaining period of energization. If as a result of this adjustment the period of energization is reduced to zero, then the controller will switch off the solenoid energizing channel so that delivery of fuel and gas will cease. However, if the remaining period is not reduced to zero then the solenoid will continue to be energized and fuel and gas will continue to be delivered. At the next half milli-second period the sequence is~repeated.
Reverting to the determination of the period of ; energizing of~the solenoid, if at that time the engine is -~ not in that part of its cycle when fuel is to be delivered, ` the~newly determined period of energization is stored. If within the then current half milli-second interval the :
engine`enters thé~part of its cycle when fuel is to be , delivered,~then the so~lenoid will be energized for the newly determlne'd`period.~In~the~event that the engine does not ~enter th~e~part of its cycl~e for the delivery of fuel during the~half~milli-second~interval, then at the end of that peri~od;the`~sequence~is~repeated~as~above explained.
Comme~rcial~l~y~avallable componentry can be arranged and~programm'ed~to~per,form~the,;~functions requi;red to fulfill the;~above~discussed logic d'iagram. Also,other factors may be~introduced~t~o~vary~the~period~that the solenoid is ~O:~energized~ In~automotlve~applications one factor that may be~
taken~lnto~ac~count,;ls~the~`voltage of the electrical energy source~to~operat~e~the~solenoid.
T~he~voltage o~f~the~battery~provided ln an auto~
mobile~m'ay~ vary~signi~fi'cant~ly;~under operating conditions ~~
3~5 -~fr~`'m=the~nomi;nal~ rated~ 2~volts~. Slgnificant drop in voltage ,can~occur~a~t~times~when~high `loads are applied to the ~ ~`
. ~ : . . . ; . . : . . . .
lZ~7S33 battery, such as cranking the engine during start-up. In order to compensate for this drop in voltage available to energize the solenoid, the period of energization may be extended.
The electronic controller 192 may thus incorporate a function to compare the actual voltage available to the solenoid against the battery rated voltage and if the actual voltage is below rated, an extension of the period of energization of the solenoid may be made. The degree of extension of the period relative to the drop in voltage may be pre-programmed into the electronic cont~oller.
The period of energization of the solenoid may be expressed by the formula p~ ~ = PWo ~ PWbv + PWACT
~ Where PWe is actual period of energization , ' PW is a basic period of energization o PWbv is battery voltage compensation ,, . ~ period ~ ~ PWAcT is actuator rod position compensa- -tion period Typlcally~PWO is the period of energization at no-load on the`engine and may~be of the order of 12 to 15 milli-" ~seconds,~and the~maximum increase ln response to the actua-tlon~rod~position~may be~5~to~10 ml11i-seconds, the increase belng~linear;over~the range of movement of the actuator rod.
The~increase~in~energiza~tion~period~for decline in battery voltàgè~may~;be of~the~;~o~rder of 0.~5~mi11i-seconds per~volt.
~The~increase~of 5 to 10 mi11i-seconds~ for actuation rod ;~ ~ posltion~ls~fo~r ful]-~fuel~llng~under transient~load condition --~30 ~and~is~considerably~greater~ of the order of 50%) than that ~ ~ requi~red~under~fu;ll--open-throttle~steady conditions. The `~ ~ total time~p'er cyclé~that the~solenoid may be energised is of cour,s~e;'l'imi~ted~by~the~;cycle time of the engine and the tim~`required~t~o~fi~ the~met~ering chamber wlth fuel, the 35~ ;1atter~be~i;ng~of~the~order~of~8 milli-seconds.
It~is~des'irable from~combustion efficiency consi-`'`d~er~ion~for~'injection of the fuel to terminate at a fixedin'`th'e~engine cycle.~Acco~r~dlngly,~when the perlod oE
` ~337533 ~ 13 -energization of the solenoid is varied the termination point of the energization remains fixed and the additional time is obtained by advancing the initiation point of the ener-gization. Figure 4 of the drawings shows a typical variation in the duration of application of the air to the fuel being delivered in relation to the output of the potentiometer that is directly related to the quantity of fuel being delivered.
In the preceding description the period of energization of the solenoid has made the variable in response to variations in metered quantities of fuel. How-ever, it is to be understood that the purpose in varying that period is to achieve a corresponding variation in the mass of air available to effect the delivery of the metered quantity of fuel. As the pressure of the air supply is maintained constant by suitable pressure regulators, and in practical terms temperature variations normally encountered do not significantly influence the density of the air, the mass of air delivered to the metering chamber is directly related to the period that the air is available via the ; 20 solenoid valve 150.
~ When the englne is under transient conditions, requiring a~rapid increase in fuelling, it can be difficult to control-~a fuel metering and injection system to deliver thè optimum amount of fuel. From commencement of a transient the~first~one or two cycles of each cylinder should prefer-ably~havs~a higher~fuel loadlng than when operating at the same~throttle openlng~fo~r ste~ady state operation. This immed-`~ iate~enrichment~of~the fuel mixture is required to give the engine an acceptable rapid response when the throttle is suddenly~opened~. It has now been found that an acceptabletrans~ient~resp~onse can be obtained from an engine utilizing the~f`uel~me~tering~system~described above by increasing the ma;s~s;:of~the;~a~ir~availa~ble to deliver the fuel that is not :`
~`dependent~on~any~ increase in~the metered quantity of fuel.
35~ During~op~eration of an engine, the internal surfaces~of~the~fu~el delivery path, comprising delivery condult~108~ and~associated injector nozzle 18, remain wetted 12~7~ii3;~
by the ~uel after each delivery of fuel and air through the nozzle 18 to the engine. During substantially smooth engine operation (i.e. steady state or light acceleration or decele-ration) this residual wetting of the internal surfaces has no significant effect on the operation of the engine, as the amount of fuel retained by the wet surfaces remains substan-tially constant while the amount of air used for each delivery is constant.
Figure 5a illustrates the desired sequential fuel deliveries from the nozzle 18, for an engine transient requiring an immediate increase in fuel rate between deliver-ies 5 and 6. Figure 5b shows typical delivered fuel quanti-ties where the fuel metering and injection system is arranged so that each of the twelve deliveries of fuel are propelled by the same mass of air. The degree of residual wetting of delivery line 108 is increased for increased metered quanti-ties of fuel, and the amount of fuel delivered from the injector nozzle is seen to increase gradually between deliveries 5 and 9. From the first delivery at the new fuel metering rate, the amount of fuel delivered from nozzle 18 would be less than the metered quantity determined at the ` position of the metering rod 115 in the metering chamber 1~0, bècause the mass of air available cannot immediately handle the~increased quantity of fuel, and there is an increase in the residual wetness on the internal surfaces. However, the amount of fuel retained wettlng delivery line 108 is a func-tlon~both~of the ~quantlty~of fuel metered at the metering chamber,~and of the mass of the air used to deliver the - metered fuel along the conduit and out of the nozzle.
~Consider now Figure 5c where each delivery is ~ derived~from the same metered quantity~of fuel being in the `~ ~ metering chamber~l~20.~However, the mass of air for delivery 6~has~been made larger than the others, by energizing the s`olenoi~d~for a longer period. Delivery 6 ejects more fuel 3~5`~ from~the~nozzl~e 18 than de~livery 5, as it has reduced the quantity~of fuel wetting the inner surfaces o delivery line ; 108~ Furth~er, de~livery 7~passes correspondingly less fuel ~ : .
.
. - . : , ~ .. . :
.. .. : . . . :, . :: . .:
.,- , . . . .
.. -.. : , ~ . .. . ..
~ Z ~ 3 than delivery 5 as some fuel will be left in the delivery line 108 rewetting the surfaces. Subsequently delivery using the normal mass of air will deliver an amount of fuel from the nozzle corresponding to the metered quantity available in the metering chamber 120.
Referring now to Figure 5d, this illustrates a repeat of the engine transient conditions of Figure 5a except the system is now arranged so that the increased amount of fuel is propelled by an increased mass of air. Delivery 6, being the first delivery at the increased metered quantity of fuel and mass of air, will leave the delivery line 108 slightly less wet than the preceding delivery 5, while following pulses 7-8-9 etc., will maintain that reduced degree of~wetting. The effect on delivered fuel quantities can be seen in Figure 5d. The transient fuel enrichment is evident.~It will be appreciated that this arrangement ~provides also the desirable fuel enleanment on deceleration ~translents~due to the delivery line 108 entering a stage of lncreased residu~al~wetting. ~
~ T~he use of;the~capab;ility of reducing the wetness of the;internal surface~;of~the~fuel delivery conduit is prèferabl~y~in combination~with~the increase;in~metered quantit~y;~of fuel as; represented by~Figure~Sd,~ particularly when~the~e~ngine~ s~experienc~lng~a~severe transient condi-tion~ H~owe~ver,~eithe~r~ca`pabili~ty may~be used individually The~;ele~c~tronIc~c;ontroller~192; may~be ~arranged~to respond to a~t~ranslent~condltlon~s~ensed~by a~factor other~than the~
actuator~r`od~pos~it~ion~in~order;t~o~imp~lement~operation of the~
wetnes~s~reducti~on`~capabi~l~ity~,~such`as~by sensing the~rate of~ 0 ~ change~of~the~thrott1e~positlon.~
t~wl~ll however~be~appreciated that the invention de~scrlbed~ hereln~l~s~ not~restrlcte~d to the particular appa~ratus~déscribed~ n~detail~above, but is applicable to all~fuel meteri;ng~and/or~del~ivery~sys~tems utilizing a pulse of gas:to-propel a~metered~:quantlty of fuel for delivery to The metered t~uantity of fuel will depend on engine load, transient state, engine cylinder size, and selected operating air/fuel ratio, and may typically range from a few milligrams up to say 100 milligrams (or more) per injection.
Correspondingly, the preferred mass of air delivered to the metering chamber per injection may vary over the range 2 milligrams to 10 ~or more) miliigrams per injection. An approximate volumetric ratio of air to fuel measured at S.T.P. is 50:1. Air supply pressures are regulated but metering operation may be achieved typically using supply pressures over the range 200kPa to 1000kPa (or even higher).
Practically, the minimum pressure is determined by the need to operate valves, and to supply sufficient air mass, so that 400kPa is a more usual value. Similarly, maximum pressures tend to be determined according to the need for simple and efficient supply sources. In an automotive - application~a single~stage compressor would be desired, effectively limiting maximum pressures to around 800kPa.
~ ~Under some engine operating~conditions it may be desirable to lncre~ase the mass ~of alr per injection even though there is no corresponding increase in fuel quantity.
One~such condition~may be~during start-up of the engine particular~ly under cold start~conditions. The additional air will contr~ibute to improved atomization, particularly when 25 the~e`nglne is cold~and~vaporlzation i5 not~assisted by the ~i heat of the engine~
~ The~engine c~ondition in response to which the mass of air~is~varied may be timed from start-up so the air mass decreases~as the~time after start-up increases until the air~
30 ~mass;~fall;s~to~a predètermined;limit. ~If the engine condi-tion is~temperature~, again the air mass will decrease as the temperature increases until a predetermined limit is reached.
- . : ~ : , : . . ....................... .
. - . - . . . . . . .
, - : , , -.,
Claims (23)
1. A method of delivering liquid fuel to an engine to ensure increases in the metered quantity of fuel provide substantially corresponding increase in the quantity of fuel actually delivered to the engine, said method compris-ing collecting in a chamber having a delivery port a metered individual discrete unit of fuel, adjusting the fuel quantity of each discrete unit in relation to the engine load, admitting a pulse of gas to the chamber and opening the delivery port to displace the discrete fuel unit from the chamber and deliver same to the engine, said gas pulse being delivered to the chamber at a selected pressure which is at least substantially independent of the quantity of discrete fuel unit, and achieving increases in the quantity of fuel delivered to the engine substantially corresponding to increases in the quantity of the metered individual discrete unit of fuel over at least part of the range of engine load by increasing the duration of the gas pulse admitted to the chamber during increased fuel quan-tity deliveries to increase the mass of air available to overcome changes in inertia and viscosity effects arising from the increased fuel quantities.
2. Method of claim 1, wherein the duration of the gas pulse admitted to the chamber is increased in direct proportion to the increase in the quantity of fuel in the discrete fuel unit.
3. Method of claim 1 or claim 2, wherein the meter-ed quantity of fuel in the discrete fuel unit is metered prior to delivery of the fuel to the chamber.
4. Method of claim 1 or claim 2, wherein the quan-tity of fuel in the discrete fuel unit is metered by con-trolling the relative positions of entry of the gas to and the discharge of fuel from said chamber.
5. A method of delivering liquid fuel to an engine to ensure increases in the metered quantity of fuel provide substantially corresponding increase in the quantity of fuel actually delivered to the engine, said method compri-sing collecting a metered individual discrete unit of fuel in a chamber having a selectively openable discharge port in communication with a conduit terminating in a nozzle;
admitting a pulse of gas at a selected pressure to said chamber to displace the fuel unit from the chamber upon opening of the discharge port to propel the fuel along the conduit and discharge the fuel through the nozzle, control-ling the quantity of fuel displaceable by the admission of said gas pulse to the chamber in accordance with the fuel demand of the engine, and achieving increases in the quan-tity of fuel delivered to the engine substantially cor-responding to increases in the quantity of the metered in-dividual fuel units over at least a part of the range of engine load by increasing the duration of the gas pulse admitted to the chamber during increased fuel quantity de-liveries to increase the mass of air available to overcome changes in inertia and viscosity effects in the conduit arising from the increased fuel quantities.
admitting a pulse of gas at a selected pressure to said chamber to displace the fuel unit from the chamber upon opening of the discharge port to propel the fuel along the conduit and discharge the fuel through the nozzle, control-ling the quantity of fuel displaceable by the admission of said gas pulse to the chamber in accordance with the fuel demand of the engine, and achieving increases in the quan-tity of fuel delivered to the engine substantially cor-responding to increases in the quantity of the metered in-dividual fuel units over at least a part of the range of engine load by increasing the duration of the gas pulse admitted to the chamber during increased fuel quantity de-liveries to increase the mass of air available to overcome changes in inertia and viscosity effects in the conduit arising from the increased fuel quantities.
6. A method as claimed in claim 5, wherein the con-trol of the quantity of fuel in the discrete fuel unit is effected by adjusting an relative positions of entry of the gas to and discharge of the fuel from said chamber.
7. Apparatus for delivering a metered quantity of liquid fuel to an engine while ensuring that increases the metered quantity of fuel provide substantially correspond-ing increases in the quantity of fuel actually delivered to the engine, said apparatus comprising a chamber having a selectively openable discharge port, supply means for sup-plying fuel to said chamber to provide therein an indivi-dual metered discrete unit of fuel, control means for controlling the quantity of fuel in said discrete unit in accordance with engine fuel demand, gas means for selec-tively admitting a pulse of gas to the chamber at a selected pressure which is at least substantially indepen-dent of the quantity of the discrete fuel unit to displace the discrete fuel unit from the chamber upon opening of the discharge port, and adjustment means for increasing the duration of the gas pulse admitted to the chamber during increased fuel quantity deliveries to achieve increases in the quantity of fuel delivered to the engine which substan-tially correspond to increases in the quantity of the metered individual discrete fuel units over at least part of the range of engine load by increasing the mass of air available to overcome changes in inertia and viscosity affects arising from the increased fuel quantities.
8. Apparatus as claimed in claim 7, including at least two members forming said chamber, at least one of said members being movable relative to the other of said members to vary the volume of the chamber and thus vary the quantity of fuel in said discrete fuel unit.
9. Apparatus as claimed in claim 8, wherein said discharge port is provided in one of said members, and a gas inlet port through which the gas is admitted to the chamber is provided in other of said members, with the rela-tive disposition of the discharge port and the gas inlet port being adjustable by relative movement between the mem-bers to control the quantity of fuel in the discrete unit displaceable by the admission of the gas.
10. Apparatus as claimed in claim 8, wherein said adjustment means includes position means to determine the relative position of the two members, and means responsive to the determined relative position for controlling the duration of the pulse of gas admitted to the chamber.
11. Apparatus of clalm 7, wherein said chamber in-cludes a gas inlet port through which the gas pulse is ad-mitted to the chamber, and fuel quantity control means for controlling the quantity of the discrete unit of fuel dis-placeable from the chamber, said fuel quantity control means including a member which forms a portion of said chamber and has said gas inlet port formed therein, said member being movable relative to the discharge port in said chamber so that the quantity of said discrete unit of fuel displaceable by the admission of the gas pulse is deter-mined by the position of said gas inlet port.
12. Apparatus of claim 11, wherein said adjustment means includes means to determine the relative position of the gas inlet port in the chamber, and means responsive to the determined relative position for controlling the dura-tion of the gas pulse admitted to the chamber.
13. Apparatus of claim 7, including valve means for controlling the admission of the gas pulse to the chamber, said adjustment means including means for opening said val-ve means for a controlled period, and means responsive to the engine fuel demand for adjusting the duration of the period that the valve means is open for each fuel delivery.
14. Apparatus of claim 13, wherein said valve means is solenoid actuated, and the means responsive to the engine fuel demand energizes said solenoid for a period pro-portional to the fuel demand.
15. A method of delivering liquid fuel to an engine having a given air fuel ratio at steady state conditions, said method comprising collecting in a chamber having a delivery port a metered individual discrete unit of fuel, adjusting the fuel quantity of each discrete unit in rela-tion to the engine load, admitting a pulse of gas to the chamber and opening the delivery port to displace the dis-crete fuel unit from the chamber and deliver same to the engine, said gas pulse being delivered to the chamber at a selected pressure which is at least substantially inde-pendent of the quantity of the discrete fuel unit, and im-proving the fuel atomization under cold start conditions by increasing the mass of air per injection over that of steady state conditions by increasing the duration of the gas pulse admitted to the chamber.
16. A method of delivering liquid fuel to an engine, comprising the steps of:
collecting a metered quantity of fuel in a chamber, said quantity of fuel varying with the fuel demand of the engine;
admitting compressed gas to the chamber to displace therefrom a metered quantity of fuel; and varying the mass of gas admitted to the chamber with variations in the fuel demand of the engine at least over part of the range of the engine fuel demand so that as the fuel demand increases or decreases the mass of gas admitted to the chamber increases or decreases.
collecting a metered quantity of fuel in a chamber, said quantity of fuel varying with the fuel demand of the engine;
admitting compressed gas to the chamber to displace therefrom a metered quantity of fuel; and varying the mass of gas admitted to the chamber with variations in the fuel demand of the engine at least over part of the range of the engine fuel demand so that as the fuel demand increases or decreases the mass of gas admitted to the chamber increases or decreases.
17. A method as claimed in claim 16, wherein the mass of gas admitted to the chamber is varied by varying the period of time during which the gas is admitted to the chamber.
18. A method as claimed in claim 16, wherein the mass of gas admitted is varied proportional to the variation in the quantity of fuel to be di placed.
19. A method as claimed in claim 16, 17 or 18, wherein the metered quantity of fuel is measured prior to delivery to the chamber.
20. An apparatus for delivering a metered quantity of liquid fuel to an engine, comprising:
a chamber having a selectively openable discharge port;
means for collecting a metered quantity of fuel in said chamber;
means for admitting gas to the chamber to displace the fuel therefrom upon opening of the discharge port;
means for controlling the quantity of fuel collected in the chamber in accordance with engine fuel demand; and
a chamber having a selectively openable discharge port;
means for collecting a metered quantity of fuel in said chamber;
means for admitting gas to the chamber to displace the fuel therefrom upon opening of the discharge port;
means for controlling the quantity of fuel collected in the chamber in accordance with engine fuel demand; and
21 means for varying the mass of gas admitted to the chamber with a variation in the fuel demand so that as the fuel quantity increases the gas mass increases.
21. The apparatus of claim 20, including a valve means for controlling the admission of gas to the chamber, and wherein the means for varying the mass of gas include means for opening said valve means for a controlled period, and means, responsive to the engine fuel demand, for adjusting the duration of the period that the valve means is open for each fuel delivery.
21. The apparatus of claim 20, including a valve means for controlling the admission of gas to the chamber, and wherein the means for varying the mass of gas include means for opening said valve means for a controlled period, and means, responsive to the engine fuel demand, for adjusting the duration of the period that the valve means is open for each fuel delivery.
22. The apparatus of claim 21, wherein the valve opening means is solenoid actuated, and the means responsive to the engine fuel demand are adapted to energise said solenoid for a period proportional to the fuel demand.
23. A method of delivering liquid fuel to an engine, comprising the steps of:
collecting a metered quantity of fuel in a chamber;
varying said metered quantity of fuel in response to the fuel demand of the engine;
delivering compressed gas to the chamber to displace the metered quantity of fuel and deliver said fuel to the engine; and, varying the mass of gas delivered to the chamber to deliver said fuel in response to the variations in a selected engine condition.
collecting a metered quantity of fuel in a chamber;
varying said metered quantity of fuel in response to the fuel demand of the engine;
delivering compressed gas to the chamber to displace the metered quantity of fuel and deliver said fuel to the engine; and, varying the mass of gas delivered to the chamber to deliver said fuel in response to the variations in a selected engine condition.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPG6875/84 | 1984-08-31 | ||
| AUPG687584 | 1984-08-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1287533C true CA1287533C (en) | 1991-08-13 |
Family
ID=3770740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000489636A Expired - Fee Related CA1287533C (en) | 1984-08-31 | 1985-08-29 | Delivery of metered quantities of fuel to an engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS61123760A (en) |
| CA (1) | CA1287533C (en) |
| DE (1) | DE3531486A1 (en) |
| FR (1) | FR2569775B1 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE348523B (en) * | 1968-06-17 | 1972-09-04 | Politechnika Krakowska | |
| AU523968B2 (en) * | 1978-04-14 | 1982-08-26 | Orbital Engine Company Proprietary Limited | Metering liquid fuel using chamber evacuated by gas pressure |
| JPS58155276A (en) * | 1981-12-31 | 1983-09-14 | オ−ビタル・エンジン・カンパニイ・プロプライエタリ・リミテイツド | Method and device for feeding liquid fuel to internal combustion engine |
| JPS58155269A (en) * | 1981-12-31 | 1983-09-14 | オ−ビタル・エンジン・カンパニイ・プロプライエタリ・リミテイツド | Method and device for supplying engine with liquid fuel by gas pressure |
| PH20932A (en) * | 1981-12-31 | 1987-06-05 | Orbital Engine Comp Proprietar | Liquid metering apparatus |
| DE8408103U1 (en) * | 1984-03-16 | 1985-05-02 | Pierburg Gmbh & Co Kg, 4040 Neuss | FUEL SUPPLY DEVICE FOR MIX-COMPRESSIVE COMBUSTION ENGINES |
-
1985
- 1985-08-29 CA CA000489636A patent/CA1287533C/en not_active Expired - Fee Related
- 1985-08-30 DE DE19853531486 patent/DE3531486A1/en not_active Withdrawn
- 1985-08-31 JP JP60193015A patent/JPS61123760A/en active Pending
- 1985-09-02 FR FR8513023A patent/FR2569775B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3531486A1 (en) | 1986-04-17 |
| FR2569775B1 (en) | 1989-11-17 |
| JPS61123760A (en) | 1986-06-11 |
| FR2569775A1 (en) | 1986-03-07 |
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