CA1108951A - Fuel injector - Google Patents
Fuel injectorInfo
- Publication number
- CA1108951A CA1108951A CA360,676A CA360676A CA1108951A CA 1108951 A CA1108951 A CA 1108951A CA 360676 A CA360676 A CA 360676A CA 1108951 A CA1108951 A CA 1108951A
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- valve
- piston
- actuator
- port
- metering
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Abstract
FUEL INJECTOR
ABSTRACT OF THE DISCLOSURE
A fuel injector, especially adapted for diesel engines, is disclosed in which injection timing and fuel metering may be controlled from cycle to cycle of engine operation. Means are provided to control the timing of the injection independently of the metering of the fuel quantity for the injection cycle. The injector comprises an injector pump and timing valve means, including a solenoid valve and a shuttle valve, which controls the energization of the pump to execute an injection stroke. It also comprises metering valve means, including a solenoid valve and a shuttle valve, which controls the return stroke of the injector pump to meter the fuel quantity to be injected on the injec-tion cycle.
ABSTRACT OF THE DISCLOSURE
A fuel injector, especially adapted for diesel engines, is disclosed in which injection timing and fuel metering may be controlled from cycle to cycle of engine operation. Means are provided to control the timing of the injection independently of the metering of the fuel quantity for the injection cycle. The injector comprises an injector pump and timing valve means, including a solenoid valve and a shuttle valve, which controls the energization of the pump to execute an injection stroke. It also comprises metering valve means, including a solenoid valve and a shuttle valve, which controls the return stroke of the injector pump to meter the fuel quantity to be injected on the injec-tion cycle.
Description
This invcntion relates to fuel injection s~Jstems for internal combustion engines and mo~e particularl~
it relates to an improved injector. rhe improved in-jec~or is adapted for precise timing and metering of the fuel injection by electronic control signals governed by engine operating conditions.
This application is a division of applicant 7 S
copending parent application Serial No. 313,319, filed on October 13, 1978.
In the operation of internal combustion engines with fuel injection, especially diesel engines, both the timing and the quantity of fuel injection are important in obtaining the desired performance. In some engines it is necessary to in~ect large quantities of fuel at high pressure. Further, the operating parameters which determine the optimum timing for injection may vary independently of those parameters which determine the optimum quantity of fuel with such variations occurring from one engine cycle to the next. It is presently known to utiliæe an electronic computer to develop control signals for inJection timing and metering which can be changed from one engine cycle to the next in aecordance with engine operating parameters, such as speed setting, m~nifold vacuum9 atmospheric pressure and the like.
In the prior art, it has been proposed to provide a fuel in~ector in whlch the tlmlng of the in~ect-lon i8 controlled independently of the Euel quantlty of the injection. S~ch an arrangement Ls shown In the Bassot et al. U.S. Patent 3,516,3g5, Is~3ued .Jnnc 23, 1970. In the inJector of this patent an electromagnetlc v~lve if, opened for a controlled time period to admit fuel under con~sptant pressure to a metering chamber for lnjection.
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The timing of the initiation of lnjection is controlled by an engine operated 3-way valve which admits fluld pressure to the servo cylinder to actuate the i,njection piston. In the Hussey et al. U.S. Patent 3,587,547, issued June 28, 1971, the timing and metering of the injection are controlled separately, the metering being performed by opening a fuel distributing valve for a controlled time period. It has also been proposed to control the metering of fuel for each injection hy controlling the length of the injection stroke of the injector piston by controlling the quantity of the actuating fluid for the piston. This is described in the Sampietro U.S. Patent 2,946,513, issued July 26, 1960.
: Fuel in~ectors utilizing an electromagnet for controlling the timing and metering of the fuel injection are well known in the prior art. The Komaroff U.S. Patent 3,623~460, issued November 30, 1971, discloses an injector in which the injector piston is actuated dlrectly by an electromagnet on both the forward and reverse strokes.
On the reverse stroke, the fuel is metered by the amount of time that the piston is retracted from the neutral position and injection is initiated by the forward stroke.
In the injector of the Links U.S. Patent 3,835,829, issued September 17, 1974, a single solenoid valve controls the metering and the timing of the fuel in~ection. When the solenoid is de~energized fuel flows into the yump chamber and when it is energized ~he fuel pressure cnerglzes - the servo piston and causes in~ection to occur. In the in~ectors described in these patents, the meterlng depends upon the length of the time period and the value of the supply pressure during which fuel flows into the metering ~ chamber. Solenoid controlled in~ectors are also shown in - mb/~,?: - 2 -~ r-~
the Monpetit et al. U.S. Pa~ent 3,680,782, if.sued Augllst 1~ 1972 and the Reneault e~ a]. U.S. Patellt 3,802,626, issued April 9, 1974.
It is known to provide an injector with a spool valve for controlling the energization of ~he servo ~iston and to employ a pilot valve to control the spool valve, as shown in Takahashi et al. U.S. Patent 3,943,091, issued March 9, 1976. In the injector of this patent a single pilot valve, either a monostable or a bistable fluid element, energizes the servo piston through the pilot valve when it is in one position and it actuates thne spool vaIve tode-energiæe ~he servo piston when the pilot valve is in the other position. The timing and the quantity of fuel injection both depend upon the duration of the control signal on the pilot valve.
An object of the present invention :is to provide an injector which overcomes certain disadvantages of the prior art~ especially in respect to the manner and precision with which -timing and metering i5 executed for each injection of fuel.
According to the present invention there is provided a fuel injector for an internal combustion engine, the engine being provided with a fuel supply source and a drain with the source at higher pressure ~han the drain.
The injector has an injector bod~ member including a first fluid passage adapted to be in fluid communic~tlon with the source and a second fluid pa~sagc adapt~(l to he in communication with the drain. An in~ector no~,zle 1~
provided and a fuel metering chamber i~ ln communicatLon with the nozæle and in communication wlth thc first passage. An in~ector piston i~ provided in the metering chamber and is movable to expel fùel therefrom to the nozzle. The injector has an actuator chamber, an actuator mb/~/,;, 3 ', piston in the actuator chaml~er which i5 movabl~ in response to fluid pressure in the actuator c~amber. The injector piston is connected with the actuator piston and is movable therewith. A timing valve has an inlet adapted to be in communication with the source o~ actuator fluid under pressure and has an o~ltlet in communication with the actuator chamber. A metering valve has an inlet in communication with the actuator chamber and outlet adapted to be in communication with an actuator fluid drain. Control means is provided for the timing and metering valves for independent actuation thereof wherehy opening the metering valve for a predetermined time period while the timing valve is closed causes the injector piston to move outwardly of the metering chamber to provide a predetermined volume of fluid in the metering chamber and opening of the timing valve while the metering valve is closed causes the actuator piston to actuate the inJector piston and expel fluid from the metering chamber to the no~zle.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE 1 is a diagram of a fuel injection system ;embodylng the present invention;
FIGURE 2 shows the fuel injector of this invention in cross-section through its longitudinal axis;
FIGUR~ 3 shows the fuel in~ector ln plan vlew;
FIGURE 4 is a vlew taken on llnes 4-4 of ~GURE ~;
FIGURE 5 ls a view taken on lines 5~S of FIGURE 4;
FIGURE 6 is an enlarged sectlonal vlew taken on lines 6-6 oE FIGURE 3;
FIGURR 7 is a sectional view taken on lines 7 7 of FIGURE 6;
FIGURE 8 i~ a fragmentary vlew show-lng details of construction, and .
mb/~,' ~ 4 ~ `3 P-303 _5~
FIGURE 9 is a timing diagram for use in explaining th.e operation of the injector o~ this in~enti.on.
BEST MODE FOR CARRYING OUT THE INVENTION
Re~erring now to t~e drawings, there is shown an illustrative. em~odiment o~ the invention in a fuel injector especially adapted for use with a diesel en~ine. The injector is of unitary construction and adapted to be mounted in the cylinder head of the engine. It is adapted to ~e connected with a remote fuel supply source and draln and is responsive to electrical control signals from a remote electronic control unit.
The Injector in a Tvpical Svstem:
Referring now to FIGURE 1, the illustrative embodiment of the invention is shown in a fuel injection system for a two-cylinder diesel engine. The system com?rises an injector 10 for one cylinder of the engine and an identical injector 12 for the other cylinder of the engine. A fuel supply source including a tank 14 is adapted to deliver fuel under pressure to the in~ectors. The source comprises a pump 16 having an inlet conduit connected with the tank 14 and an outlet conduit connected to a pressure regulator 18. The regulated output of the pressure regulator 18 is supplied oYer a common rail or conduit 20 to khe injectoxs, A br~nch supply conduit 22 is connected with. a fue.l ~upply .inlet 24 o~ injector 10~ An accumulator 26 is suitably connected ~ith the branch supply conduit 22 r Similarly, a branch.supply conduit 28 extends ~r~m the common condui.t ZU to a fuel supply - iplet 3Q o~ i.njector 12 and i~ provided ~ith an ~ccumulator 32. The ~uel system ~u~ther.comprises a common drai~ conduit 34 connected with the tank 14.
P-3~3 -6-The injector 10 has a ~irst drain outlet 36 connected through a branch drain conduit 38 to the common conduit 34; it also has second and third drain outlets 40 and ~2 connected with. the common drai.n conduit 34 through bxanch s drain conduits 44 and 46~ respectively. In similar manner, the injector 12 is connec~ed with branch drain conduits 48, 50 and 52.
The fuel injection system, as shown in FIGURE 1, also comprises an electronic control unit 54 which is adapted to provide control signals to the individual injectors lO and 12 in accordance with engine operating conditions. In order to provide proper timed relation or phasing of the control unit 54 with the engine, a trigger signal generator (not shown) is driven in synchronism with the engine and produces a trigger signal TR which is applied to the control unit 54. The trigger signal is suitably of rectangular waveform having the leading 1 -edge of a rising pulse occur at top dead center of the .
piston in the first cylinder and having a leading edge of a ~alling pulse occur at top dead center of the piston in the second cylinder. The electronic control unit is also adapted to receive data signals indicative of instantaneous values of engine operating parameters from one or more suitable transducers for the purpose of computing the optimum timing, i.e. injection advance, and the quantity of each fuel injection. A throttle signal S, indicative of the desired engine speed, is representative of such data signals and is applied to th.e control un.it 54 as indicated in FIGURE 1.
The electronic control unit 54 al50 comprises a p~iX o~ output texminals or ports 56 and 58 which are electric~lly connected by condwctors 60. and 62 to respective input texminals or ports 64 and 66 on injector 10, Th.e e.lectronic control unit also comprises a pair of output ports 68 and 70 whi.ch are connected respectively over conductors 72 and 74 with respective input ports on injector 12, The injectors 10 and 12, a~ stated ahoye, are identical to e~ch other; the injector lO will no~ be described in detail, General Arran~ement o~ the ~uel In'iector:
S In general, as shown in FIGURES 2 through 8, the injector comprises an injector nozzle 76 and an injector pump 78 which supplies ~uel at a desired injection pressure to the nozzle. The injector pump 78 is controlled by timing valve means 80 and by metering valve means 82 to cause the injection of a predetermined metered quantity of fuel at a predetermined time during each engine cycle, The fuel in~ector comprises a housing or body member 84 which supports the timing valve means 80 and the metering valve means 82 and also provides for connection of a fuel supply source and drain. The body mem~er 84 comprises an upper body portion of circular cross-section and a lower hody portion having flat front and rear faces. The fuel supply inlet 24 is provided on the body mem,ber 84 and a fuel supply passage 85 (see FIGURES 3, 4 and 5) extends transversel~ in the body member. Also, the first fuel drain outlet 36 an~ interconnected drain passages 86 and 88 are provided in the body member.
As shown in FIGURE 2, the injector pump 78 is mounted on the ~ody mernber 84 and the injector nozzle 76 depends fxom the pump 78. The pump 78 and the nozzle 76 are secured to the body member 84 by a flange member 87 which is held to the body mem~er 84 by a pair of ' ' threaded asteners 89.
The injector pump 78 will now be described in detail ~ith re~erence to FIGURES 2 and 4. The injector pump 78 compri~es a ~um~ body 9~ which de~ines an actuator ch~mbex ~ and the metering ch~mber ~4. The pu~p is fitted ~,ith a,~pump pi,~ton ~5 including an actu~tor piston ~6 in the actuator chamber and an injector piston ~8 in the meterin~ chamber~ The actuator ,:
piston is of substantially larger diameter than the injector piston and hence energization of the pump hy admitting fuel supply pressure into the actuator chamber 92 produces an amplified ~luid pressure in the 5 metering chambex ~4~ The amplification ratio i5 selected so that the fluid pressure in the metering chamber is equal to or greater *~an the required injection pressure~ i.e. the value required to actuate the injector nozzle. The actuator piston and the injector piston are connected together, suitably as an integral structure. ~n enlarged annular chamber 100 be~ween the actuator chamber and the metering chamber is connected through a passage 102 to the transverse drain passage 88 and thence through the passaye 86 to 15 the drain outlet 36. The actuator piston of the pump is energized by timing valve means 80 to produce a fo~ard stroke of the injector piston 98 in the meter-ing chamber and is conkrolled by the metering valve means 82 to produce a return stroke of the injector 20 piston. The me$ering chamber 94 is connected to the fuel supply source and to the nozzle as described below.
The nozzle 76 is of known construction and is connected with the pump 78 by the flange member 87. The nozzle comprises a holder ~ody 103 having a head portion retained by the flange mem~er 87 and also comprises a holder nut 104 which is threaded onto the lower end o~
the holderbody 103, The lower end of the holder nut 104 is provided with threads for screwing the injector - into the cylinder head o the engine. The nozzle 76 includes ~ nozzle body 106 which is xetained within the holder nut and is provided with an annular chamber 108 communicating with an axially exkending noæzle outlet passage. A needle yalve 110 in the nozzle bod~ is adap~ed to engage a ~alve ~eat 112 to open and close communic~tion bet~een the chamber 108 and the nozzle outlet passage, The needle ~alve 110 is biased toward ~Lh~
the closed po~ition by a helical spring 114 seated within t~e holder ~ody 103, An adaptor 116 is disposed between the lower end o~ t~e spring and the upper end of the needle valve 110. A stop plate 118 is disposed S hetween the upper end of the nozzle ~ody 106 and the lower end of the holder ~ody 103, A stem on the needle ~alve llQ extends through the stop plate into engagement ~ith the adaptor 116. A spray tip 120 is connected with the nozzle hody 106 and held in assembled relation 10 therewith b.y the holder nut 104. The spray tip is in fluid communication with the outlet passage of the nozzle body and is adapted to deliver fuel in a fine mist to the combustion ch.am~er of the engine.
For the purpose of supplying fuel to the nozzle, 15 an axially extending ~uel supply passage 122 is-in fluid communication with the fuel pressuxe supply passage 85.
This is suitably provided through a calibrating oriice which.is adjustably set by a cali~rating needle 124 (see FIGURE 4~. A check valve 126 has its inlet in 20 communicatlon with the passage 122 and its outlet connected through a passage 128 to the uel metering chamber 94 in the pump 78. The metering chamber is connected through a nozzle supply passage 130 in the pump ~ody and in the holder body to an annular passage 25 i32 ~see FIGURE 21 in the upper surface of the stop plate 118. The annular passage 132 communicates with a passage.134 which.extends through the stop plate 118 and through the nozzle body 106 to the annular chamber 108. It will be understood as the description proceeds 30 that fuel under pressure from the fuel supply sou~ce i5 deliYered from the supply pa~sage ~5 to the meteriny ch~mber 94 and thence to the nozzle in xeadiness for injection inko the en~ine cylinder.
5~
The Timing Valve Means:
The timing valve means 80 i.s pro~ided to energize the pump 78 and thus initiate injection o~
fuel into the cyli,nder at a predetermined time i,n the engine cycle. The. timing valve means 80~ as sho~wn in FIGUR~S 2, 6 and 7~ compri,ses a spool or shut~le val~e 140 andan electromagnetic pilot or solenoid valve 142.
In general, the timing means 80 is adapted to energize the pump 78 by admitting pressurized fluid thereto, namely fuel from the supply passage 85, in response to an electrical timing signal which. energizes the solenoid yalve 142. As will he understood, the combina-- tion of the solenoid valve and the shuttle valve is used in order to achieve fast response and sufficient 15 power amplification to actuate the pump. '' The shuttle valve 140 comprises a valve body 144 which defines a cylînder 146 which receives a valve element or spool valve 148. The shuttle valve body 144 has an inlet port 150 which is connected ' through an axial passage 152 (extending through body 144 and body member 84) to a ~ransverse passage 154 which intercepts the fue]. supply passage 85. The transverse passage 154 is closed at the fron~ face of the lower portion of body member 84 by a plug 156. The .valve bod~ 144 defines an outlet port 158 which is connected through an axial passage 160 which extends : through a transverse passag~ 161 to an axial passage 162 and thence to the actuating chamber 92. The passage 161 is closed by a plug 164 in the face of the body me~ber 84.
. Th.e cylinder 146 in the valve body 144 includes ~ lower cylinder portion 166 (,see FIGURE 6) of reduced di.amete~ which opens :into a transverse - passaye 168 whi.ch is in communication with the fuel supply passage 152. The spool valve 148 defines an - annular gxoove 170 and includes a stem 172 which ex-tends into the lower cyl m der portion 166~ Fuel pre~sure thus acts on the reduced area of the s.tem 172 and tends to ur~e the spool valve in a direction to align the annular groove 170 ~ith th.e inlet and outlet ports 150 and 158 to open the valve. ~ drain passa~e 171 extends f~om the lower end o~ the cylinder 146 to the transverse drain passage 88 to remove any fluid which le~aks past the spool valve, Th.e drain passage 88 is connected through passa~e 86 with the drain outlet 36 and is closed at its outer end ~ty a plug 173. The operation of the shuttle val~e 140 is controlled by the solenoid val~e 142 in a manner tha~ will now be described.
The solenoid valve 142, as shown in FIGURES
6 and 7, is a 3-way valve in that it is provided with 15 three ports and may be operated so that one port communicates exclusively with either of the other two.
The solenoid valve 142 comprises a valve body 174 defin-ing a cylinder 192, a first valve element or sleeve - valve 176 slidably disposed within cylinder 192, and a Z0 second valve element or post valve 178 which is slidable relative to the sleeve. The valve body 174 is disposed in alignment with the valve body 144 of the shuttle ~al~e 140 and is mounted in an adaptor 180 which is threadedly engaged with the upper portion of the body mem~er 84. The solenoid valve further comprises an electromagnet 182, in the form of an E-core and coil, which is potted inside a cover member 184.
The electromagnet 182 is separated from the valve body . 174 by a nonm~gnetic spacer ring 186 and a flange nut .~ :
188 engages the coyer 184 and i6 threadedly secured to th.e adaptor 18Q. The solenoid valve 142 ~urther com-prises an armature l9Q of ma~neti.c mater.ial disposed in the. ~pa~é between the electromagnet 182 and the Yalve body 174, Th~ ~rmature. l~Q is o~ annular con-fi~uration and is secured, as ~ a press ~it, to theupper end of:th.e valve sleeve 176.: The valve sleeve . - , , , ,. . ,, ,:
8~
176 is movable to an upper position when the electro-ma~net is energi.zed and to a lo~er position when it is de-energized, as explained bslow~ The valYe post 178 is slidabl~ disposed with.in th.e sleeve. 176 and is provided with a spacer 194 o nonmagnetic material at its upper end. Th.e spacer is secured on a reduced portion of the post, as ~y press fitting, and engages a ~ias spring 196 which is seated in a recess of the E-core 182.
Th~ yalve port arrangement of the solenoid Yalye 142 is as follows. The valve body 174 defines a pressure inlet port 198 which communicates with the fuel supply passage 152.. The sleeve valve 176 is provided with. a port 200 which communicates with khe port 198.
The sleeve valve 176 h.as an enlarged in~ide diameter below the port 20~ to provide an annular chamber 201 which opens into a lower port 202 at the end of the sleeve valve. The port 202 opens into the cylinder 146 of the shuttle ~alve body 144. The lower end of the post valve 178 is adapted to close ayainst a valve seat 204 on the sleeve val~7e 176 and prevents communication between th.e pressure inlet port 198 and the port 202 when the sleeve valve 176 is in its upper position.
An exhaust port 206 is provided in the valve body 174 iat the lower end o the cylinder 192. This port communicates through a passage 208 to the space surround-ing th.e armature l90 and thence through passage 210 in - the E-core potting to the second drain outlet 40. In order to proYide ~or opening and closing o~ the exhaust port 206, the valve ~ody 174 i5 provided with a valve seat 212 wh.ich coacts with the lower end of the sleeve v~lYe 192. ~hen the electxoma~net 182 is de-energized the ~leev~ valve 192 is closed and the post valve 178 is opened ~t ~eat 204 ~y the action of the ~luid pres-35 sure in ~h.e annulax cha~er 201; when the electromagnetis energi~ed the sleeve ~alvè 192 is opened at seat 212 and the post valve 178 is closed ak seat 204.
In ~ummary~ the solenoid yalve 142 ~unctions as ~ollows. When the electromagnet 182 îs de-en~r~ized, the sleeye valYe 176 is in its lower position. This closes the sleeve valYe against the ~alve seat 212 ~nd it opens the post valve 178 at the valve seat ~04.
This provides communication between the pressure inlet port 198 through port 200 in the sleeve valve to the port 202, thus admitting pressure to the upper end of the spool valve 148~ CIn this condition the 1uid pressure on the lower end of the valve post 178 is suficient to overcome the ~orce of the ~ias spring 196 and the valve post is seated against the face of the E-core.) When the electromagnet 182 is energized the armature 190 holds the sleeve valve 192 in its upper position. In this condition the post valve 178 is seated against the valve seat 204, thus closing communication between the pressure inlet port 198 and the port 202. Also, in this condition, ~ith t~e sleeve valve 192 in its upper ~0 position, the sleeve valve is lifted off the valve seat 212 and the upper end of the cylinder 146 is con-nected with the exhaust port 206.
The solenoid valve 142 controls the shuttle valve 140 in the ~ollowing manner. When the electro-~5 ~agnet 182 is de-energized, the sleeve valve 192 is in its lower position and the pressure inlet port 198 is connected with the port 2Q2 and ~uel under pressure is admitted to the upper end of valve cylinder 146. As noted above, ~uel under pressure is al~ays acting on ~he valve stem 172. Because o the di~erential area of the valve $tem 172 and the upper end o~ the spool valve - 148~ the spool ~al~e is moYed to iks lower position.
This disconnects the inlet po~t 15Q rom the outlet p~rt 158. When the electroma~net 182 is energized, the sleeve val~e 176 is moved to its upper position and the post valve 178 closes against the valve seat 204 ~3~
P 3~3 -14-and cuts o~f the fuel supply press-ure to cylinder 146.
At the same time, the sleeve valve i.s lifted from the valve seat 212 and th,e cylinder 146 is connected with th,e exh.aust port 206 and the fuel pressure in cylinder 146 is relieved. Consequently, the spool valve 1~8 is moved to its uppex position by the ~uel supply pressure acting on the valve stem 172. This connects the pressure inlet port 150 with the outlet port 158 and fuel supply pressure is applied through the passages 160, 161 and 162 to the ac~uator chamber 92. In summary, ~he shuttle valve 140 is opened by energizing the solenoid valve 1~2 and pressure is admitted to the actuator chamber 92 of injector pump 78. When the solenoid valve 142 is de-energized the shuttle valve 140 is closed and the fuel supply pressure is cut off from the actuator chamber 92.
The Metering Valve Means:
The metering valve means 82, as stated above, performs the function of controlling the quantity oE fuel to be injected in~o the cylinder for each engine cycle.
As will appear more fully below, this is accomplished by controlling the return stroke of the injector pump 78 to set the injector chamber 128 for a predetermined volume.
The metering valve means 82, as shown in FIGURES
25 2 and 8, is similar in construction to the timing valve .-means 80; in fact, th.e solenoid valve 142' is identical to the solenoid valve 142. Accordingly, those parts in the metering vaIve means 82 which are identical to parts in ~he timing valve means 80 are given reference characters 30 D~ the same nlImber but with a prime 8ym~01. In view oX
this similarity~ de~cription o the solenoid valve 142 and its mounting structure is omi.tted.
The ~etering v~lve means 8Z comprises, in addition to the solenoid valve 142l, a spool or shuttle 35 valye 2140 The shuttle valve 214 comprises a valve body 21~ which defines a cylinder 218 which receives a spool valve 220. The valve hody 216 defines an inlet port 222 - - \
5~
P~303 -15-wh.ich communicates through a pas~age 223 and thence through. passages 161 and 162 with.the actuator chamber 92. Th~ ~alve ~ody 216 also defines an outlet port 224 which is connected through an axial pa~sage 226 to a transverse drain passage 86 ~hich is connected with the drain outlet .36 (in ~ody member 84, see FIGURE
3~. A drain passage 234 extends from th.e lower portion of cylinder 218 to th.e transverse drain passage 88 to drain any fluid ~hich leak.s past t~e valve spool.
The spool valve 220 is provided with a stem 238 which extends througn a reduced portion of the cylinder 218 to the lower end of the valve body. A
transverse passage 240 (see FIGURE 3? extends from the fuel supply passage 152~ to the lower end of the 15 reduced cylinder portion. The fuel supply passage 152' and transverse passage 240 deliver fuel supply pressure ~ :
to the stem 238 to urge the spool valve 220 toward its upper position.
When the solenoid valve 1~2' is de-energized, 20 fuel supply pressure is applied through the solenoid ~ :
~alve to the cylinder 218. Since the upper face of :~
the spool valve 220 is of larger area than the face of the stem 238, the spool valve is in its lower position when the solenoid valve is de-energized. In this posi-25 tion the spool valve 220 closes the inlet port 222 and .-i :
the outlet poxt 224. With the shuttl~ valve closed, the line 224 is closed so that there is no release of fluid supply pressure in actuator chamber 92. When the solenoid val~e 142' i.s energized the shuttle valve 214 30 is opened and the fuel supply pres~llre in the actuator chamh.er 9.2 is reli.eved b~ connectlon to th.e drain th.rough.passages 162, 161 and 223, ports 222 and 86 and pas~age$ 226 and 86. The ~e~uencing o~ the metering yal~e means 82 in relation to tha~ of the timin~ valve 35 means 80 will ~e described below.
~'L'~
Operation:
The operation of the injector o~ this inyention will now ~e described with.particular re~erence to FIGURES 1, 2, 4 and ~ The fuel suppl~ at re~ulated pressure is admi.tted to the injector at the inlet port 24. The fuel is supplied to the metering chamber 94 through the ~uel supply passage 85, the orifice of calibrating needle 124, passage 122 and thence through the check.val~e 126 and passage 128. For explanatory purpose~, it will be assumed that the injector is in a state of readiness for initiatin~ an injection cycle.
In this condition, hoth. the ti~iny solenoid 142 and the metering solenoid 142' are de-energized and the shuttle valves 140 and 214 are closed. Accordingly, the pump piston ~5 is urged ~y the fuel supply pressure in th.e metering chamber 94 to a position determined by the quantity of fluid trapped in the actuator chamber 92 by ths closure of the shuttle valves. (This conditian will be more fully descri~ed below in connection with the injection cycle.~ In this state of readiness ~or injection, fuel under reyulated pressure thus fills the metering chamber 94 and also fills the supply passages to the nozzle 76. The nozzle supply passages include passages 130, 132, 134 and the annular chamber 108 at ;the needle valve lI0, as shown in FIGURES 2 and 4. The regulated fuel supply pressure in the annular chamber 1~8 is insufficient to lift the needle valve 110 off its seat agains.t the bias force of the spring 114.
Accordingly~ the needle ~alve. remains closed and the ;.
injector nozzle is ~nactiVe ~ut in a state of readiness for ~uel injectlon.
In ordex tQ control th.e ~et o~ injectors of - an eng~ne in timed relation with.engine ope~ation, electric~l contxol signals ~rom the electronic control unit 54 are.applied to the respective injectors. This will be descri~ed with re~erence to FIGU~ES 1 and 9 P-303 ~17-which represent the injector operation in a 2-cylinder engine. The trigger signal TR ~hi.ch.is supplied to the electronic control uni.t 54 is generated in ~ynchronism with engine rotation and one cycle o~ the trigger signal corresponds to one revolution ~f t~e engine, As ~hown in FIGUR~ 9, during the first one,~half revolution o~
the engine crank.shaft, from top dead center (,TDC) in cylinder #l to TDC in cylinder ~2, the trigger signal is high and during the second one-half revolution the trigger signal is low. The control signals to be described are generated ~y t~e control unit 54 so that injector 10 of cylinder #1 produces a timed fuel injection during the second one-half revolution and the injector 12 of cylinder ~2 produces timed fuel injection during lS the first one~half cxankshaft revolution.
The electronic control unit 54 produces', for the injector 10 of cylinder #1, a timing signal Tl which -i"' includes timing pulses tpl, tp2, etc. which are of a fixed time duration or pulse width. The timing pulses are produced by the con~rol uni~ 54 at a variable injection advance angle or timing before top dead center~ In the example of FIGURE 9, the timing pulse tpl occurs at a time tl before top dead center, and the timing pulse tp2 occurs at a time t2 before top dead :
center. It is noted that the timing pulses tpl and tp2 ' occur with their leading edges at an injection advance angle which varies frvm one engine cycle to the next ~ccording to th.e computation of the optimum injection advance ~or th.e su~Sisting engine conditions. The ~ :
control unit 54 al~o produces, for the injector 10 of cylinder #1, a meterin~ signal Ml ~h.ich includes meter~
: in~ pulses m~l~ mp2r etc, ~hich are. o~ variable ti.me duration or pulse ~idt~.~ Each metering pulse is in:L~ated a~ter th.e texmination of the immediately preceding ti~ing pulse and the time duxation thereo varie~ from one cycle to thé next ln accordance with the computed .
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P-303 ~18~
value of fuel quantity to be injected to obtain optimum engine performance under the ~u~sisting operating conditions. Th,e timing pulses have a typical time dura-tion of about one mi,llisecond ~hereas, the metering pulses have a typical value in the range of several milliseconds. The time duration of the timing pulses, as mentioned above, is suita~ly of constant value and must be at least as long as the time required for the pump piston of the injector to execute a for~ard stroke.
0 Each metering pulse may he inîtiated at any time in the engine cycle proyided that it does not overlap the preceding timing pulse or the succeeding timing pulse.
Similarly, in the example of FIGURE 9, the timing signal T2 comprises timing pulses tp3, tp4, etc. which are of fixed time duration and which occur at times t3 and t4, respectivel~, ~efore top dead center for cylinder #2. Also, for cylinder #2, the control unit produces metering signal M2 including metering pulses mp3, mp4, etc. having time durations of m3 and m4, respectively.
, With injector 10 in readiness for an injection cycle, as described above, the timing pulse tpl is applied to the timing solenoid 142. This causes the shuttle valve 140 to open and fuel is admitted at regulated supply pressure to the actuator chamber 92 of the pump piston 95. This energizes the actuator piston 96 and the in~ector piston 9B executes a forward stroke into the metering chamber 94,. The forward stroke of the injector piston ~8 extends from its initial or rest position to a fixed stop position in which the forward end o~ the actuator piston 96 seats against a lower'wall o the annulax chambex 100, This for~ard strok,e o~ the in~ector piston 98 produces high 1uid press~xe in t'he metering chambex 94 which exceeds the regulated fuel pressure in accoxdance with the ampli-- 35 ~ication produced ~y the pump pi~ton. Thus, the check valve 126 is closed and the pressure in the metering .
P~303 -lg-chamber and in the nozzle passages 130, 132~ 134 and the annular chamber 108 e:xceeds the injecti.on p~essure and li~ts the needle valve 110 off its valve seat 112, Accordingly, i.n;ection occurs through. the nozzle body 106 and the spray tip 120 At the end of the forward stroke o~ the pump piston the needle valve 110 closes and the injection is ended At the end o~ the timing pulse tpl, the solenoid 142 is de-energized and the shuttle valve 14Q is closed. ~s a result, the supply of fuel under pressure is removed from the actuator chamber 92 but the actuating fluid in ~he chamber is trapped by the closure of the shuttle valve 140 and the pump piston 95 remains in position at the forward end of its strok.e. When the metering pulse mpl occurs, the metering solenoid 142~ is energized and th-e shuttle valve 214 is opened. This allows the fluid trapped in the actuating chamber 92 to ~e exhausted through :
the passages 162, 161, 223, to the inlet of the shuttle valve and thence through the outlet 224 of the valve and the passage 226 to the exhaust port 36. As a result, the pump piston 95 is moved in its return stroke by the press1lre of the fuel in the metering chamber 94.
The rate of movement of the piston in its return stroke ~-is governed by the rate of ~uel flow into the metering ;chamber which is adjustably set by the calibrating needle 124. The pump piston 95 including the injector piston 98 and actuator piston 96 conkinue to move in th.e return st~ok.e until the shuttle valve 214 is closed ~or`until the piston reaches. its full return position.) 30 When the metering pulse mpl is terminated the solenoid - --yal~e 142 is de-energ~zed and th.e shuttle valve 21~ is closed. ~hen the sh.uttle ~alve 21~ is closed, the ~luid in th.e actuati.ng chamber ~2 is trapped and the motion o the pi.ston is arrested~ Th.us the lnjector piston 98 is he.ld in a predetermined position, according to the time duration o~ the metering pulse, to set the volume of th.e metering chamber and the quantiky of the ~uel to ~e injected on the next injection cycle.
It will ~e appreciated that the operation of the injector 12 i,n cylinder #2 is similar ~o that just descri~ed for injector lO. In each injector~ the timing solenoid is energized at a predetermined time in the engine cycle, and after injection has occurred, the metering solenoid is independently energized for a predetermined time period to establish. the quantity of fuel injection for t~e next injection cycle. This energization is repPated during each engine cycle.
Although the description o~ this invention has been given with reference to a particular embodiment it is not to be construed in a limiting sense. Many variations and modificatlons will now occur to those skilled in the art. For a definition of the invention, rc~erenco is made to the appended claims.
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it relates to an improved injector. rhe improved in-jec~or is adapted for precise timing and metering of the fuel injection by electronic control signals governed by engine operating conditions.
This application is a division of applicant 7 S
copending parent application Serial No. 313,319, filed on October 13, 1978.
In the operation of internal combustion engines with fuel injection, especially diesel engines, both the timing and the quantity of fuel injection are important in obtaining the desired performance. In some engines it is necessary to in~ect large quantities of fuel at high pressure. Further, the operating parameters which determine the optimum timing for injection may vary independently of those parameters which determine the optimum quantity of fuel with such variations occurring from one engine cycle to the next. It is presently known to utiliæe an electronic computer to develop control signals for inJection timing and metering which can be changed from one engine cycle to the next in aecordance with engine operating parameters, such as speed setting, m~nifold vacuum9 atmospheric pressure and the like.
In the prior art, it has been proposed to provide a fuel in~ector in whlch the tlmlng of the in~ect-lon i8 controlled independently of the Euel quantlty of the injection. S~ch an arrangement Ls shown In the Bassot et al. U.S. Patent 3,516,3g5, Is~3ued .Jnnc 23, 1970. In the inJector of this patent an electromagnetlc v~lve if, opened for a controlled time period to admit fuel under con~sptant pressure to a metering chamber for lnjection.
mb/<~
: ., : ,:
The timing of the initiation of lnjection is controlled by an engine operated 3-way valve which admits fluld pressure to the servo cylinder to actuate the i,njection piston. In the Hussey et al. U.S. Patent 3,587,547, issued June 28, 1971, the timing and metering of the injection are controlled separately, the metering being performed by opening a fuel distributing valve for a controlled time period. It has also been proposed to control the metering of fuel for each injection hy controlling the length of the injection stroke of the injector piston by controlling the quantity of the actuating fluid for the piston. This is described in the Sampietro U.S. Patent 2,946,513, issued July 26, 1960.
: Fuel in~ectors utilizing an electromagnet for controlling the timing and metering of the fuel injection are well known in the prior art. The Komaroff U.S. Patent 3,623~460, issued November 30, 1971, discloses an injector in which the injector piston is actuated dlrectly by an electromagnet on both the forward and reverse strokes.
On the reverse stroke, the fuel is metered by the amount of time that the piston is retracted from the neutral position and injection is initiated by the forward stroke.
In the injector of the Links U.S. Patent 3,835,829, issued September 17, 1974, a single solenoid valve controls the metering and the timing of the fuel in~ection. When the solenoid is de~energized fuel flows into the yump chamber and when it is energized ~he fuel pressure cnerglzes - the servo piston and causes in~ection to occur. In the in~ectors described in these patents, the meterlng depends upon the length of the time period and the value of the supply pressure during which fuel flows into the metering ~ chamber. Solenoid controlled in~ectors are also shown in - mb/~,?: - 2 -~ r-~
the Monpetit et al. U.S. Pa~ent 3,680,782, if.sued Augllst 1~ 1972 and the Reneault e~ a]. U.S. Patellt 3,802,626, issued April 9, 1974.
It is known to provide an injector with a spool valve for controlling the energization of ~he servo ~iston and to employ a pilot valve to control the spool valve, as shown in Takahashi et al. U.S. Patent 3,943,091, issued March 9, 1976. In the injector of this patent a single pilot valve, either a monostable or a bistable fluid element, energizes the servo piston through the pilot valve when it is in one position and it actuates thne spool vaIve tode-energiæe ~he servo piston when the pilot valve is in the other position. The timing and the quantity of fuel injection both depend upon the duration of the control signal on the pilot valve.
An object of the present invention :is to provide an injector which overcomes certain disadvantages of the prior art~ especially in respect to the manner and precision with which -timing and metering i5 executed for each injection of fuel.
According to the present invention there is provided a fuel injector for an internal combustion engine, the engine being provided with a fuel supply source and a drain with the source at higher pressure ~han the drain.
The injector has an injector bod~ member including a first fluid passage adapted to be in fluid communic~tlon with the source and a second fluid pa~sagc adapt~(l to he in communication with the drain. An in~ector no~,zle 1~
provided and a fuel metering chamber i~ ln communicatLon with the nozæle and in communication wlth thc first passage. An in~ector piston i~ provided in the metering chamber and is movable to expel fùel therefrom to the nozzle. The injector has an actuator chamber, an actuator mb/~/,;, 3 ', piston in the actuator chaml~er which i5 movabl~ in response to fluid pressure in the actuator c~amber. The injector piston is connected with the actuator piston and is movable therewith. A timing valve has an inlet adapted to be in communication with the source o~ actuator fluid under pressure and has an o~ltlet in communication with the actuator chamber. A metering valve has an inlet in communication with the actuator chamber and outlet adapted to be in communication with an actuator fluid drain. Control means is provided for the timing and metering valves for independent actuation thereof wherehy opening the metering valve for a predetermined time period while the timing valve is closed causes the injector piston to move outwardly of the metering chamber to provide a predetermined volume of fluid in the metering chamber and opening of the timing valve while the metering valve is closed causes the actuator piston to actuate the inJector piston and expel fluid from the metering chamber to the no~zle.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE 1 is a diagram of a fuel injection system ;embodylng the present invention;
FIGURE 2 shows the fuel injector of this invention in cross-section through its longitudinal axis;
FIGUR~ 3 shows the fuel in~ector ln plan vlew;
FIGURE 4 is a vlew taken on llnes 4-4 of ~GURE ~;
FIGURE 5 ls a view taken on lines 5~S of FIGURE 4;
FIGURE 6 is an enlarged sectlonal vlew taken on lines 6-6 oE FIGURE 3;
FIGURR 7 is a sectional view taken on lines 7 7 of FIGURE 6;
FIGURE 8 i~ a fragmentary vlew show-lng details of construction, and .
mb/~,' ~ 4 ~ `3 P-303 _5~
FIGURE 9 is a timing diagram for use in explaining th.e operation of the injector o~ this in~enti.on.
BEST MODE FOR CARRYING OUT THE INVENTION
Re~erring now to t~e drawings, there is shown an illustrative. em~odiment o~ the invention in a fuel injector especially adapted for use with a diesel en~ine. The injector is of unitary construction and adapted to be mounted in the cylinder head of the engine. It is adapted to ~e connected with a remote fuel supply source and draln and is responsive to electrical control signals from a remote electronic control unit.
The Injector in a Tvpical Svstem:
Referring now to FIGURE 1, the illustrative embodiment of the invention is shown in a fuel injection system for a two-cylinder diesel engine. The system com?rises an injector 10 for one cylinder of the engine and an identical injector 12 for the other cylinder of the engine. A fuel supply source including a tank 14 is adapted to deliver fuel under pressure to the in~ectors. The source comprises a pump 16 having an inlet conduit connected with the tank 14 and an outlet conduit connected to a pressure regulator 18. The regulated output of the pressure regulator 18 is supplied oYer a common rail or conduit 20 to khe injectoxs, A br~nch supply conduit 22 is connected with. a fue.l ~upply .inlet 24 o~ injector 10~ An accumulator 26 is suitably connected ~ith the branch supply conduit 22 r Similarly, a branch.supply conduit 28 extends ~r~m the common condui.t ZU to a fuel supply - iplet 3Q o~ i.njector 12 and i~ provided ~ith an ~ccumulator 32. The ~uel system ~u~ther.comprises a common drai~ conduit 34 connected with the tank 14.
P-3~3 -6-The injector 10 has a ~irst drain outlet 36 connected through a branch drain conduit 38 to the common conduit 34; it also has second and third drain outlets 40 and ~2 connected with. the common drai.n conduit 34 through bxanch s drain conduits 44 and 46~ respectively. In similar manner, the injector 12 is connec~ed with branch drain conduits 48, 50 and 52.
The fuel injection system, as shown in FIGURE 1, also comprises an electronic control unit 54 which is adapted to provide control signals to the individual injectors lO and 12 in accordance with engine operating conditions. In order to provide proper timed relation or phasing of the control unit 54 with the engine, a trigger signal generator (not shown) is driven in synchronism with the engine and produces a trigger signal TR which is applied to the control unit 54. The trigger signal is suitably of rectangular waveform having the leading 1 -edge of a rising pulse occur at top dead center of the .
piston in the first cylinder and having a leading edge of a ~alling pulse occur at top dead center of the piston in the second cylinder. The electronic control unit is also adapted to receive data signals indicative of instantaneous values of engine operating parameters from one or more suitable transducers for the purpose of computing the optimum timing, i.e. injection advance, and the quantity of each fuel injection. A throttle signal S, indicative of the desired engine speed, is representative of such data signals and is applied to th.e control un.it 54 as indicated in FIGURE 1.
The electronic control unit 54 al50 comprises a p~iX o~ output texminals or ports 56 and 58 which are electric~lly connected by condwctors 60. and 62 to respective input texminals or ports 64 and 66 on injector 10, Th.e e.lectronic control unit also comprises a pair of output ports 68 and 70 whi.ch are connected respectively over conductors 72 and 74 with respective input ports on injector 12, The injectors 10 and 12, a~ stated ahoye, are identical to e~ch other; the injector lO will no~ be described in detail, General Arran~ement o~ the ~uel In'iector:
S In general, as shown in FIGURES 2 through 8, the injector comprises an injector nozzle 76 and an injector pump 78 which supplies ~uel at a desired injection pressure to the nozzle. The injector pump 78 is controlled by timing valve means 80 and by metering valve means 82 to cause the injection of a predetermined metered quantity of fuel at a predetermined time during each engine cycle, The fuel in~ector comprises a housing or body member 84 which supports the timing valve means 80 and the metering valve means 82 and also provides for connection of a fuel supply source and drain. The body mem~er 84 comprises an upper body portion of circular cross-section and a lower hody portion having flat front and rear faces. The fuel supply inlet 24 is provided on the body mem,ber 84 and a fuel supply passage 85 (see FIGURES 3, 4 and 5) extends transversel~ in the body member. Also, the first fuel drain outlet 36 an~ interconnected drain passages 86 and 88 are provided in the body member.
As shown in FIGURE 2, the injector pump 78 is mounted on the ~ody mernber 84 and the injector nozzle 76 depends fxom the pump 78. The pump 78 and the nozzle 76 are secured to the body member 84 by a flange member 87 which is held to the body mem~er 84 by a pair of ' ' threaded asteners 89.
The injector pump 78 will now be described in detail ~ith re~erence to FIGURES 2 and 4. The injector pump 78 compri~es a ~um~ body 9~ which de~ines an actuator ch~mbex ~ and the metering ch~mber ~4. The pu~p is fitted ~,ith a,~pump pi,~ton ~5 including an actu~tor piston ~6 in the actuator chamber and an injector piston ~8 in the meterin~ chamber~ The actuator ,:
piston is of substantially larger diameter than the injector piston and hence energization of the pump hy admitting fuel supply pressure into the actuator chamber 92 produces an amplified ~luid pressure in the 5 metering chambex ~4~ The amplification ratio i5 selected so that the fluid pressure in the metering chamber is equal to or greater *~an the required injection pressure~ i.e. the value required to actuate the injector nozzle. The actuator piston and the injector piston are connected together, suitably as an integral structure. ~n enlarged annular chamber 100 be~ween the actuator chamber and the metering chamber is connected through a passage 102 to the transverse drain passage 88 and thence through the passaye 86 to 15 the drain outlet 36. The actuator piston of the pump is energized by timing valve means 80 to produce a fo~ard stroke of the injector piston 98 in the meter-ing chamber and is conkrolled by the metering valve means 82 to produce a return stroke of the injector 20 piston. The me$ering chamber 94 is connected to the fuel supply source and to the nozzle as described below.
The nozzle 76 is of known construction and is connected with the pump 78 by the flange member 87. The nozzle comprises a holder ~ody 103 having a head portion retained by the flange mem~er 87 and also comprises a holder nut 104 which is threaded onto the lower end o~
the holderbody 103, The lower end of the holder nut 104 is provided with threads for screwing the injector - into the cylinder head o the engine. The nozzle 76 includes ~ nozzle body 106 which is xetained within the holder nut and is provided with an annular chamber 108 communicating with an axially exkending noæzle outlet passage. A needle yalve 110 in the nozzle bod~ is adap~ed to engage a ~alve ~eat 112 to open and close communic~tion bet~een the chamber 108 and the nozzle outlet passage, The needle ~alve 110 is biased toward ~Lh~
the closed po~ition by a helical spring 114 seated within t~e holder ~ody 103, An adaptor 116 is disposed between the lower end o~ t~e spring and the upper end of the needle valve 110. A stop plate 118 is disposed S hetween the upper end of the nozzle ~ody 106 and the lower end of the holder ~ody 103, A stem on the needle ~alve llQ extends through the stop plate into engagement ~ith the adaptor 116. A spray tip 120 is connected with the nozzle hody 106 and held in assembled relation 10 therewith b.y the holder nut 104. The spray tip is in fluid communication with the outlet passage of the nozzle body and is adapted to deliver fuel in a fine mist to the combustion ch.am~er of the engine.
For the purpose of supplying fuel to the nozzle, 15 an axially extending ~uel supply passage 122 is-in fluid communication with the fuel pressuxe supply passage 85.
This is suitably provided through a calibrating oriice which.is adjustably set by a cali~rating needle 124 (see FIGURE 4~. A check valve 126 has its inlet in 20 communicatlon with the passage 122 and its outlet connected through a passage 128 to the uel metering chamber 94 in the pump 78. The metering chamber is connected through a nozzle supply passage 130 in the pump ~ody and in the holder body to an annular passage 25 i32 ~see FIGURE 21 in the upper surface of the stop plate 118. The annular passage 132 communicates with a passage.134 which.extends through the stop plate 118 and through the nozzle body 106 to the annular chamber 108. It will be understood as the description proceeds 30 that fuel under pressure from the fuel supply sou~ce i5 deliYered from the supply pa~sage ~5 to the meteriny ch~mber 94 and thence to the nozzle in xeadiness for injection inko the en~ine cylinder.
5~
The Timing Valve Means:
The timing valve means 80 i.s pro~ided to energize the pump 78 and thus initiate injection o~
fuel into the cyli,nder at a predetermined time i,n the engine cycle. The. timing valve means 80~ as sho~wn in FIGUR~S 2, 6 and 7~ compri,ses a spool or shut~le val~e 140 andan electromagnetic pilot or solenoid valve 142.
In general, the timing means 80 is adapted to energize the pump 78 by admitting pressurized fluid thereto, namely fuel from the supply passage 85, in response to an electrical timing signal which. energizes the solenoid yalve 142. As will he understood, the combina-- tion of the solenoid valve and the shuttle valve is used in order to achieve fast response and sufficient 15 power amplification to actuate the pump. '' The shuttle valve 140 comprises a valve body 144 which defines a cylînder 146 which receives a valve element or spool valve 148. The shuttle valve body 144 has an inlet port 150 which is connected ' through an axial passage 152 (extending through body 144 and body member 84) to a ~ransverse passage 154 which intercepts the fue]. supply passage 85. The transverse passage 154 is closed at the fron~ face of the lower portion of body member 84 by a plug 156. The .valve bod~ 144 defines an outlet port 158 which is connected through an axial passage 160 which extends : through a transverse passag~ 161 to an axial passage 162 and thence to the actuating chamber 92. The passage 161 is closed by a plug 164 in the face of the body me~ber 84.
. Th.e cylinder 146 in the valve body 144 includes ~ lower cylinder portion 166 (,see FIGURE 6) of reduced di.amete~ which opens :into a transverse - passaye 168 whi.ch is in communication with the fuel supply passage 152. The spool valve 148 defines an - annular gxoove 170 and includes a stem 172 which ex-tends into the lower cyl m der portion 166~ Fuel pre~sure thus acts on the reduced area of the s.tem 172 and tends to ur~e the spool valve in a direction to align the annular groove 170 ~ith th.e inlet and outlet ports 150 and 158 to open the valve. ~ drain passa~e 171 extends f~om the lower end o~ the cylinder 146 to the transverse drain passage 88 to remove any fluid which le~aks past the spool valve, Th.e drain passage 88 is connected through passa~e 86 with the drain outlet 36 and is closed at its outer end ~ty a plug 173. The operation of the shuttle val~e 140 is controlled by the solenoid val~e 142 in a manner tha~ will now be described.
The solenoid valve 142, as shown in FIGURES
6 and 7, is a 3-way valve in that it is provided with 15 three ports and may be operated so that one port communicates exclusively with either of the other two.
The solenoid valve 142 comprises a valve body 174 defin-ing a cylinder 192, a first valve element or sleeve - valve 176 slidably disposed within cylinder 192, and a Z0 second valve element or post valve 178 which is slidable relative to the sleeve. The valve body 174 is disposed in alignment with the valve body 144 of the shuttle ~al~e 140 and is mounted in an adaptor 180 which is threadedly engaged with the upper portion of the body mem~er 84. The solenoid valve further comprises an electromagnet 182, in the form of an E-core and coil, which is potted inside a cover member 184.
The electromagnet 182 is separated from the valve body . 174 by a nonm~gnetic spacer ring 186 and a flange nut .~ :
188 engages the coyer 184 and i6 threadedly secured to th.e adaptor 18Q. The solenoid valve 142 ~urther com-prises an armature l9Q of ma~neti.c mater.ial disposed in the. ~pa~é between the electromagnet 182 and the Yalve body 174, Th~ ~rmature. l~Q is o~ annular con-fi~uration and is secured, as ~ a press ~it, to theupper end of:th.e valve sleeve 176.: The valve sleeve . - , , , ,. . ,, ,:
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176 is movable to an upper position when the electro-ma~net is energi.zed and to a lo~er position when it is de-energized, as explained bslow~ The valYe post 178 is slidabl~ disposed with.in th.e sleeve. 176 and is provided with a spacer 194 o nonmagnetic material at its upper end. Th.e spacer is secured on a reduced portion of the post, as ~y press fitting, and engages a ~ias spring 196 which is seated in a recess of the E-core 182.
Th~ yalve port arrangement of the solenoid Yalye 142 is as follows. The valve body 174 defines a pressure inlet port 198 which communicates with the fuel supply passage 152.. The sleeve valve 176 is provided with. a port 200 which communicates with khe port 198.
The sleeve valve 176 h.as an enlarged in~ide diameter below the port 20~ to provide an annular chamber 201 which opens into a lower port 202 at the end of the sleeve valve. The port 202 opens into the cylinder 146 of the shuttle ~alve body 144. The lower end of the post valve 178 is adapted to close ayainst a valve seat 204 on the sleeve val~7e 176 and prevents communication between th.e pressure inlet port 198 and the port 202 when the sleeve valve 176 is in its upper position.
An exhaust port 206 is provided in the valve body 174 iat the lower end o the cylinder 192. This port communicates through a passage 208 to the space surround-ing th.e armature l90 and thence through passage 210 in - the E-core potting to the second drain outlet 40. In order to proYide ~or opening and closing o~ the exhaust port 206, the valve ~ody 174 i5 provided with a valve seat 212 wh.ich coacts with the lower end of the sleeve v~lYe 192. ~hen the electxoma~net 182 is de-energized the ~leev~ valve 192 is closed and the post valve 178 is opened ~t ~eat 204 ~y the action of the ~luid pres-35 sure in ~h.e annulax cha~er 201; when the electromagnetis energi~ed the sleeve ~alvè 192 is opened at seat 212 and the post valve 178 is closed ak seat 204.
In ~ummary~ the solenoid yalve 142 ~unctions as ~ollows. When the electromagnet 182 îs de-en~r~ized, the sleeye valYe 176 is in its lower position. This closes the sleeve valYe against the ~alve seat 212 ~nd it opens the post valve 178 at the valve seat ~04.
This provides communication between the pressure inlet port 198 through port 200 in the sleeve valve to the port 202, thus admitting pressure to the upper end of the spool valve 148~ CIn this condition the 1uid pressure on the lower end of the valve post 178 is suficient to overcome the ~orce of the ~ias spring 196 and the valve post is seated against the face of the E-core.) When the electromagnet 182 is energized the armature 190 holds the sleeve valve 192 in its upper position. In this condition the post valve 178 is seated against the valve seat 204, thus closing communication between the pressure inlet port 198 and the port 202. Also, in this condition, ~ith t~e sleeve valve 192 in its upper ~0 position, the sleeve valve is lifted off the valve seat 212 and the upper end of the cylinder 146 is con-nected with the exhaust port 206.
The solenoid valve 142 controls the shuttle valve 140 in the ~ollowing manner. When the electro-~5 ~agnet 182 is de-energized, the sleeve valve 192 is in its lower position and the pressure inlet port 198 is connected with the port 2Q2 and ~uel under pressure is admitted to the upper end of valve cylinder 146. As noted above, ~uel under pressure is al~ays acting on ~he valve stem 172. Because o the di~erential area of the valve $tem 172 and the upper end o~ the spool valve - 148~ the spool ~al~e is moYed to iks lower position.
This disconnects the inlet po~t 15Q rom the outlet p~rt 158. When the electroma~net 182 is energized, the sleeve val~e 176 is moved to its upper position and the post valve 178 closes against the valve seat 204 ~3~
P 3~3 -14-and cuts o~f the fuel supply press-ure to cylinder 146.
At the same time, the sleeve valve i.s lifted from the valve seat 212 and th,e cylinder 146 is connected with th,e exh.aust port 206 and the fuel pressure in cylinder 146 is relieved. Consequently, the spool valve 1~8 is moved to its uppex position by the ~uel supply pressure acting on the valve stem 172. This connects the pressure inlet port 150 with the outlet port 158 and fuel supply pressure is applied through the passages 160, 161 and 162 to the ac~uator chamber 92. In summary, ~he shuttle valve 140 is opened by energizing the solenoid valve 1~2 and pressure is admitted to the actuator chamber 92 of injector pump 78. When the solenoid valve 142 is de-energized the shuttle valve 140 is closed and the fuel supply pressure is cut off from the actuator chamber 92.
The Metering Valve Means:
The metering valve means 82, as stated above, performs the function of controlling the quantity oE fuel to be injected in~o the cylinder for each engine cycle.
As will appear more fully below, this is accomplished by controlling the return stroke of the injector pump 78 to set the injector chamber 128 for a predetermined volume.
The metering valve means 82, as shown in FIGURES
25 2 and 8, is similar in construction to the timing valve .-means 80; in fact, th.e solenoid valve 142' is identical to the solenoid valve 142. Accordingly, those parts in the metering vaIve means 82 which are identical to parts in ~he timing valve means 80 are given reference characters 30 D~ the same nlImber but with a prime 8ym~01. In view oX
this similarity~ de~cription o the solenoid valve 142 and its mounting structure is omi.tted.
The ~etering v~lve means 8Z comprises, in addition to the solenoid valve 142l, a spool or shuttle 35 valye 2140 The shuttle valve 214 comprises a valve body 21~ which defines a cylinder 218 which receives a spool valve 220. The valve hody 216 defines an inlet port 222 - - \
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P~303 -15-wh.ich communicates through a pas~age 223 and thence through. passages 161 and 162 with.the actuator chamber 92. Th~ ~alve ~ody 216 also defines an outlet port 224 which is connected through an axial pa~sage 226 to a transverse drain passage 86 ~hich is connected with the drain outlet .36 (in ~ody member 84, see FIGURE
3~. A drain passage 234 extends from th.e lower portion of cylinder 218 to th.e transverse drain passage 88 to drain any fluid ~hich leak.s past t~e valve spool.
The spool valve 220 is provided with a stem 238 which extends througn a reduced portion of the cylinder 218 to the lower end of the valve body. A
transverse passage 240 (see FIGURE 3? extends from the fuel supply passage 152~ to the lower end of the 15 reduced cylinder portion. The fuel supply passage 152' and transverse passage 240 deliver fuel supply pressure ~ :
to the stem 238 to urge the spool valve 220 toward its upper position.
When the solenoid valve 1~2' is de-energized, 20 fuel supply pressure is applied through the solenoid ~ :
~alve to the cylinder 218. Since the upper face of :~
the spool valve 220 is of larger area than the face of the stem 238, the spool valve is in its lower position when the solenoid valve is de-energized. In this posi-25 tion the spool valve 220 closes the inlet port 222 and .-i :
the outlet poxt 224. With the shuttl~ valve closed, the line 224 is closed so that there is no release of fluid supply pressure in actuator chamber 92. When the solenoid val~e 142' i.s energized the shuttle valve 214 30 is opened and the fuel supply pres~llre in the actuator chamh.er 9.2 is reli.eved b~ connectlon to th.e drain th.rough.passages 162, 161 and 223, ports 222 and 86 and pas~age$ 226 and 86. The ~e~uencing o~ the metering yal~e means 82 in relation to tha~ of the timin~ valve 35 means 80 will ~e described below.
~'L'~
Operation:
The operation of the injector o~ this inyention will now ~e described with.particular re~erence to FIGURES 1, 2, 4 and ~ The fuel suppl~ at re~ulated pressure is admi.tted to the injector at the inlet port 24. The fuel is supplied to the metering chamber 94 through the ~uel supply passage 85, the orifice of calibrating needle 124, passage 122 and thence through the check.val~e 126 and passage 128. For explanatory purpose~, it will be assumed that the injector is in a state of readiness for initiatin~ an injection cycle.
In this condition, hoth. the ti~iny solenoid 142 and the metering solenoid 142' are de-energized and the shuttle valves 140 and 214 are closed. Accordingly, the pump piston ~5 is urged ~y the fuel supply pressure in th.e metering chamber 94 to a position determined by the quantity of fluid trapped in the actuator chamber 92 by ths closure of the shuttle valves. (This conditian will be more fully descri~ed below in connection with the injection cycle.~ In this state of readiness ~or injection, fuel under reyulated pressure thus fills the metering chamber 94 and also fills the supply passages to the nozzle 76. The nozzle supply passages include passages 130, 132, 134 and the annular chamber 108 at ;the needle valve lI0, as shown in FIGURES 2 and 4. The regulated fuel supply pressure in the annular chamber 1~8 is insufficient to lift the needle valve 110 off its seat agains.t the bias force of the spring 114.
Accordingly~ the needle ~alve. remains closed and the ;.
injector nozzle is ~nactiVe ~ut in a state of readiness for ~uel injectlon.
In ordex tQ control th.e ~et o~ injectors of - an eng~ne in timed relation with.engine ope~ation, electric~l contxol signals ~rom the electronic control unit 54 are.applied to the respective injectors. This will be descri~ed with re~erence to FIGU~ES 1 and 9 P-303 ~17-which represent the injector operation in a 2-cylinder engine. The trigger signal TR ~hi.ch.is supplied to the electronic control uni.t 54 is generated in ~ynchronism with engine rotation and one cycle o~ the trigger signal corresponds to one revolution ~f t~e engine, As ~hown in FIGUR~ 9, during the first one,~half revolution o~
the engine crank.shaft, from top dead center (,TDC) in cylinder #l to TDC in cylinder ~2, the trigger signal is high and during the second one-half revolution the trigger signal is low. The control signals to be described are generated ~y t~e control unit 54 so that injector 10 of cylinder #1 produces a timed fuel injection during the second one-half revolution and the injector 12 of cylinder ~2 produces timed fuel injection during lS the first one~half cxankshaft revolution.
The electronic control unit 54 produces', for the injector 10 of cylinder #1, a timing signal Tl which -i"' includes timing pulses tpl, tp2, etc. which are of a fixed time duration or pulse width. The timing pulses are produced by the con~rol uni~ 54 at a variable injection advance angle or timing before top dead center~ In the example of FIGURE 9, the timing pulse tpl occurs at a time tl before top dead center, and the timing pulse tp2 occurs at a time t2 before top dead :
center. It is noted that the timing pulses tpl and tp2 ' occur with their leading edges at an injection advance angle which varies frvm one engine cycle to the next ~ccording to th.e computation of the optimum injection advance ~or th.e su~Sisting engine conditions. The ~ :
control unit 54 al~o produces, for the injector 10 of cylinder #1, a meterin~ signal Ml ~h.ich includes meter~
: in~ pulses m~l~ mp2r etc, ~hich are. o~ variable ti.me duration or pulse ~idt~.~ Each metering pulse is in:L~ated a~ter th.e texmination of the immediately preceding ti~ing pulse and the time duxation thereo varie~ from one cycle to thé next ln accordance with the computed .
. :~ ' , ' ' ':, .,' , .
. .
P-303 ~18~
value of fuel quantity to be injected to obtain optimum engine performance under the ~u~sisting operating conditions. Th,e timing pulses have a typical time dura-tion of about one mi,llisecond ~hereas, the metering pulses have a typical value in the range of several milliseconds. The time duration of the timing pulses, as mentioned above, is suita~ly of constant value and must be at least as long as the time required for the pump piston of the injector to execute a for~ard stroke.
0 Each metering pulse may he inîtiated at any time in the engine cycle proyided that it does not overlap the preceding timing pulse or the succeeding timing pulse.
Similarly, in the example of FIGURE 9, the timing signal T2 comprises timing pulses tp3, tp4, etc. which are of fixed time duration and which occur at times t3 and t4, respectivel~, ~efore top dead center for cylinder #2. Also, for cylinder #2, the control unit produces metering signal M2 including metering pulses mp3, mp4, etc. having time durations of m3 and m4, respectively.
, With injector 10 in readiness for an injection cycle, as described above, the timing pulse tpl is applied to the timing solenoid 142. This causes the shuttle valve 140 to open and fuel is admitted at regulated supply pressure to the actuator chamber 92 of the pump piston 95. This energizes the actuator piston 96 and the in~ector piston 9B executes a forward stroke into the metering chamber 94,. The forward stroke of the injector piston ~8 extends from its initial or rest position to a fixed stop position in which the forward end o~ the actuator piston 96 seats against a lower'wall o the annulax chambex 100, This for~ard strok,e o~ the in~ector piston 98 produces high 1uid press~xe in t'he metering chambex 94 which exceeds the regulated fuel pressure in accoxdance with the ampli-- 35 ~ication produced ~y the pump pi~ton. Thus, the check valve 126 is closed and the pressure in the metering .
P~303 -lg-chamber and in the nozzle passages 130, 132~ 134 and the annular chamber 108 e:xceeds the injecti.on p~essure and li~ts the needle valve 110 off its valve seat 112, Accordingly, i.n;ection occurs through. the nozzle body 106 and the spray tip 120 At the end of the forward stroke o~ the pump piston the needle valve 110 closes and the injection is ended At the end o~ the timing pulse tpl, the solenoid 142 is de-energized and the shuttle valve 14Q is closed. ~s a result, the supply of fuel under pressure is removed from the actuator chamber 92 but the actuating fluid in ~he chamber is trapped by the closure of the shuttle valve 140 and the pump piston 95 remains in position at the forward end of its strok.e. When the metering pulse mpl occurs, the metering solenoid 142~ is energized and th-e shuttle valve 214 is opened. This allows the fluid trapped in the actuating chamber 92 to ~e exhausted through :
the passages 162, 161, 223, to the inlet of the shuttle valve and thence through the outlet 224 of the valve and the passage 226 to the exhaust port 36. As a result, the pump piston 95 is moved in its return stroke by the press1lre of the fuel in the metering chamber 94.
The rate of movement of the piston in its return stroke ~-is governed by the rate of ~uel flow into the metering ;chamber which is adjustably set by the calibrating needle 124. The pump piston 95 including the injector piston 98 and actuator piston 96 conkinue to move in th.e return st~ok.e until the shuttle valve 214 is closed ~or`until the piston reaches. its full return position.) 30 When the metering pulse mpl is terminated the solenoid - --yal~e 142 is de-energ~zed and th.e shuttle valve 21~ is closed. ~hen the sh.uttle ~alve 21~ is closed, the ~luid in th.e actuati.ng chamber ~2 is trapped and the motion o the pi.ston is arrested~ Th.us the lnjector piston 98 is he.ld in a predetermined position, according to the time duration o~ the metering pulse, to set the volume of th.e metering chamber and the quantiky of the ~uel to ~e injected on the next injection cycle.
It will ~e appreciated that the operation of the injector 12 i,n cylinder #2 is similar ~o that just descri~ed for injector lO. In each injector~ the timing solenoid is energized at a predetermined time in the engine cycle, and after injection has occurred, the metering solenoid is independently energized for a predetermined time period to establish. the quantity of fuel injection for t~e next injection cycle. This energization is repPated during each engine cycle.
Although the description o~ this invention has been given with reference to a particular embodiment it is not to be construed in a limiting sense. Many variations and modificatlons will now occur to those skilled in the art. For a definition of the invention, rc~erenco is made to the appended claims.
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Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fuel injector for an internal combuskion engine, the engine being provided with a fuel supply source and a drain with the source at higher pressure than the drain, the injector comprising:
an injector body member includiny a first fluid passage adapted to be in 1uid cornmunication with said source and a second fluid passage adapted to be in communication with said drain, an injector nozzle, a fuel metering chamber in communication with the nozzle and in communication with the firsk passage, an injector piston in the metering chamber and being movable to expel fuel therefrom to the nozzle, an actuator chamber, an actuator piston in the actuator chamber and being movable in response to fluid pressure in the actuator chamber, said injector piston being connected with the actuator piston and movable therewith, a timing valve having an inlet adapted to be in communication with a source of actuator fluid under pressure and having an outlet in communication with said actuator chamber, a metering valve having an inlet in communica-tion with said actuator chamber and an outlet adapted to be in communication with an actuator fluid drain, and control means for said timing and meter-ing valves for independenk actuation thereof whereby opening said metering valve for a predetermined time period while the timing valve is closed causes the injector piston to move outwardly of the metering chamber to provide a predetermined volume of fuel in the metering chambex and opening of the timing valve while the metering valve is closed causes the actuator piston to actuate the injector piston and expel fuel from the metering chamber to the nozzle.
an injector body member includiny a first fluid passage adapted to be in 1uid cornmunication with said source and a second fluid passage adapted to be in communication with said drain, an injector nozzle, a fuel metering chamber in communication with the nozzle and in communication with the firsk passage, an injector piston in the metering chamber and being movable to expel fuel therefrom to the nozzle, an actuator chamber, an actuator piston in the actuator chamber and being movable in response to fluid pressure in the actuator chamber, said injector piston being connected with the actuator piston and movable therewith, a timing valve having an inlet adapted to be in communication with a source of actuator fluid under pressure and having an outlet in communication with said actuator chamber, a metering valve having an inlet in communica-tion with said actuator chamber and an outlet adapted to be in communication with an actuator fluid drain, and control means for said timing and meter-ing valves for independenk actuation thereof whereby opening said metering valve for a predetermined time period while the timing valve is closed causes the injector piston to move outwardly of the metering chamber to provide a predetermined volume of fuel in the metering chambex and opening of the timing valve while the metering valve is closed causes the actuator piston to actuate the injector piston and expel fuel from the metering chamber to the nozzle.
2. The invention as defined in claim 1 wherein said control means comprises a first electrical-ly energized actuator operatively connected with said timing valve and adapted to receive a control signal, and a second electrically energized actuator operatively connected with said metering valve and adapted to receive a second control signal.
3. The invention as defined in claim 1 where-in said injector nozzle includes valve means which is opened in response to a predetermined pressure value which is higher than the pressure of said fuel supply source, the admission of actuator fluid under pressure to said actuator chamber being effective to cause the actuator piston to produce the pressure in the metering chamber in excess of said predetermined value of pressure.
4. The invention as defined in claim 3, where-in the inlet of said timing valve is in communication with the first fluid passage and the outlet of said metering valve is in communication with said second fluid passage, thereby utilizing the fuel supply source and drain for the actuator fluid.
5. The invention as defined in claim 4, where-in said actuator piston has a larger cross-sectional area than the injector piston whereby the pressure in said metering chamber is greater than the pressure in the actuator chamber.
6. The invention as defined in claim 5 including a check valve disposed between said meter-ing chamber and said first passage to prevent flow from said metering chamber to said first passage.
7. The invention as defined in claim 1 wherein said timing valve comprises a first spool valve haying a first cylinder defining the inlet and outlet of the timing valve and a first piston movable therein for opening and closing the timing valve, biasing means urging said first piston to a normally closed position, said first electrically energized actuator being operatively connected with said first piston for opening said timing valve when said actuator is energized.
8. The invention as defined in claim 7 wherein said metering valve comprises a second spool valve having a second cylinder defining the inlet and outlet of the metering valve and a second piston movable therein for opening and closing the metering valve, biasing means urging said second piston to a normally closed position, said second electrically energized actuator being operatively connected with said second piston for opening said metering valve when said second electrically energized actuator is energized.
9. The invention as defined in claim 8 wherein said biasing means for said first piston com-prises means providing communication of said first passage with both ends of said first piston, one end having a larger cross-sectional area than the other, whereby the fluid pressure of said fuel urges said first piston toward the closed position.
10. The invention as defined in claim 8 wherein said biasing means for said second piston com-prises means providing communication of said first pas-sage with both ends of said second piston, one end having a larger cross-sectional area than the other, whereby the fluid pressure of said fuel urges said second piston toward the closed position,
11. The invention as defined in claim 10 wherein said first electrically energized actuator comprises a three-way pilot valve having first, second and third ports, the first port being in com-munication with said first passage, the second port being in communication with the larger end of the first piston of the timing valve and the third port being in communication with said second passage, an electromagnet connected with said pilot valve, said pilot valve being open from said first port to said second port and closed from said second port to said third port when the electromagnet is deenergized, and said pilot valve being open from said second port to said third port and being closed from said first port to said second port when the electro-magnet is energized.
12. The invention as defined in claim 10 wherein said second electrically energized actuator comprises a three-way pilot valve having first, second and third ports, the first port being in com-munication with said first passage, the second port being in communication with the larger end of the second piston of the metering valve and the third port being in communication with said second passage, an electromagnet connected with said pilot valve, said pilot valve being open from said first port to said second port and closed from said second port to said third port then the electromagnet is deenergized.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA360,676A CA1108951A (en) | 1978-01-16 | 1980-09-19 | Fuel injector |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US869,875 | 1978-01-16 | ||
| US05/869,875 US4185779A (en) | 1978-01-16 | 1978-01-16 | Fuel injector |
| CA313,319A CA1102641A (en) | 1978-01-16 | 1978-10-13 | Fuel injector |
| CA360,676A CA1108951A (en) | 1978-01-16 | 1980-09-19 | Fuel injector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108951A true CA1108951A (en) | 1981-09-15 |
Family
ID=27165903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA360,676A Expired CA1108951A (en) | 1978-01-16 | 1980-09-19 | Fuel injector |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1108951A (en) |
-
1980
- 1980-09-19 CA CA360,676A patent/CA1108951A/en not_active Expired
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| MKEX | Expiry |