Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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
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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
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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
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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.
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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
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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
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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~
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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.
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P-303 -10
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
P-303 -11-
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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P-303 -12-
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
P-303 -13-
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~
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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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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'~
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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
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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
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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
P-303 -20
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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