Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention ralates to a fuel injection system for
supplying fuel to an internal combustion engine and of the
kind comprising a plurality of individual injection pumps
each including a reciprocable pumping plunger and means
within the pump for actuating the associated plunger, each
pump having associated therewith a fuel injection nozzle
through which the fuel displaced by the associated plunger
flows`in use, to a combustion space of the engine.
It is known to operate the plungers by hydraulic act-
uating means which in turn is controlled by an electrically
operated valve means. It has been suggested that the ylun-
gers can be operated directly by an electrically powered
device. The supply of electrical power to the valve means or
the device is controlled by a control system which is supp-
lied with signals representati~e of ~arious dssired and actual
engine operating parameters and ~ith signals indicative of the
position of the rotating parts of the engine, so that the
delivery o~ fuel occurs at the correct time. The control
of the fuel quantity presents a further problem and it has
been proposed that the control can be achieved using trans-
ducers a~sociated ~ith the pumps respectively to sense the
position of the plungers and supply a signal to the control
system which by partly energising the valves or the devices,
is able to halt the movement of the plungers during their
filling strokes. The pro~ision of the transducers and their
connection to ths control system adds to the complexity of
the fuel system and in addition the control system is made
complex because it needs to be able to respond to the signals
from each transducer and supply the necessary holding curr-
ent to maintain the position of the associated plunger
~hilst at the same time being capable of supplying current
to other of the fuel pumps. In addition the fuel quantity
supplied to each injector can vary depending upon the rel-
ative accuracy of the transducers.
The o~ject of the present invention is to provide a
system of the kind specified in a simple and conveniant form.
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According to the invention in a fuel system of the
kind specified each fuel pump includes ~n adjustable stop
member operable to determine the position attained by the
pump plunger during i~s filling stroke, linkage mean~
interconnecting the stop members, an actuating mQchanism
for setting the position of said linkage means and a trans-
ducer for providing a qignal indicative of thc setting of
said stop members~ said signal in use being supplied to a
control 3ystem which controls the operation of said actuat-
ing mechanism.
In the accompanying drawings:-
Figure 1 is a diagrammatic dr~wing of one e~ample ofa fuel sy3te~ in accordance with the in~ention9 and
Figure 2 is a ~ectional side elevation showing part
o~ the sy~tem seen in Figure 1,
Referring to the drawings~ the fuel system comprises
a plurality of pump/injector~ 9 equal in number to the
number of cylinders of the associated engine. The pump
injectors are illustrated in detail in Figure 2 and with
reference to Figure 2, each pump injector comprise3 a
housing 10 which is of general:Ly cylindrical form. Ths
housing 10 is provided with a first boss portion 11 extend-
ing axially from the housing and a ~econd boss portion 12
which extends laterall~ ~rom the hou~ing. Both boss portions
are provided with screw threads.
The first boss portion is of hollow form and defin~s
an internal step 13 against which is located the flange of
a pump barrel 14. The pump barrel 14 extend~ with clearance
within a cylindrical chamber 1~ defined within the hou3ing.
The flange of the pump barrel 14 is held in engagement with
the step 13 by means of a sleeve 16 one end of which engages
the flange, The othar end of the sleeve is of reducad
diameter and engages with a flange 17 fo~ed on an injection
nozzle assembly generally indicated at 18. The flange 17 of
the no~zla asse~bly is engaged by a retaining nut 19 which is
in screw t}~ead engagement with the boss portion 11. The
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retaining nut defines a cylindrical aperture through w~ich
part of the nozzle assembly extends and in use, the end face
of this part of the no~zle assembly together with the end
face of the retaining nut 19 are exposed within the coMbustion
cha~ber of an engine. As shown~ a step on the retaining nut
is located against a copper or like washer shown-in dotted
outline at 20 and which is located against a step defined
in a bore formed in the cylinder head of the engine.
The nozzle as3embly includes a valve member 21 one
end of which dafines a head for co-operation with a seating.
The ~alve member is biased to the closed position by means
of a coiled compression spring 220 As will be appreciated
by those skilled in the art the nozzle assembly is of ths
outwardly opening type which when fuel under pressure acts
against the aforesaid valve head, the valve member is moved
against the action of the spring to permit fuel to flow
through an outlet.
Located within the bore defined in the p~p barrel
is a pumping plunger 23. The pumping plunger extends from
the end of the barrel and defines a flange between which
and the end of the pump barrel is located a coiled compres-
sion spring 24. The flanged end of the p~mping plunger is
pro~ided with radially extending groov0s and the mo~ement
of the pumping plunger under the action of the spring 24
is limitad b~ ~butment of the pumping plunger with a
stop ring 25 which is located against a step defined in
the housing. ~loreover~ the pumping plunger is provided
with a recess which as shown, recei~es the end of a push-
rod 26.
~ uel is supplied to the space defined within the
housing in a mannerwhich will be explainsd, This fuel is
~der a small pressure and during outward mo~ement of the
pumping plunger under the action of the spring 24~fuel
is drawn into the cylinder defined by the pump barrel.
This fuel flows by way of a non-return valve qo that ~hen
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the plunger 23 is moved inwardly against the action of the
spring 24 the non-return valve remains closed and the fuel
displaced by the pumping plunger is supplied through the
nozzle assembly.
The non-return ~al~e comprises a valve member 27 having
a shank portion 28 which iq slidably supported within the
bore in the pump barrel. The valve member also includes
a ~alve head 29 which is of larger diameter than the ~hank
portion and this in the closed position of the valve membery
engages with an annular edge 30 defined at the end o~ an
enlarged portion of the bore in the barre~. The valve
membar is urged to the closed poYition by a compression
~pring 31 and extending through the valve member is a
bore 320 In addition, the barrel 14 i9 provided djacent
the flange, with a pair of radially extending ports 33.
At their outer ends the ports 33 communicate with the
space defined between the oute~r periphery of the pump
barrel and th0 ~all 15 of the chamber formed in the hou ing.
At the inner ends, the ports c:ommunicate with a circumferen-
tial ~roove 34 formed in the periphery o~ the shank 28 of
the valve member. Moreo~er, 1he shank 28 of the valve
member is of a length such that towards the end of the
strcke of the pumping plung~r, the latter will engage with
the shank and lift the valve member against the ac~ion of
the spring 31. When this occurs toward~ the end of the
delivery of fuel by the pumping plunger, the pressurQ of
fuel supplied to the nozzle iq lowered quickly to that obtain-
ing in the chamber containing tha pump barrel. The reason
for this i5 that when the valve member is lifted the groove
34 places the ports 33 in communication with the enlarged
portion of the bore beneath the head of the valve me~ber.
As a re~ult of the rapid reduction in the fuel pres~ure, the
head o~ the va]ve 21 can move quickly onto it~ seating and
the risk of fuel being supplied through the nozzle assembl~
în an unatomised condition is minimised.
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Jhen the pumping plunger is returned under the action
of the spring 24 the valve member 27 remains in a position
such that the ports 33 are in communication with the bore
and with the head 29 lifted from the edge 30. The reason
for this i5 that fuel under pressure from the ~foresaid
chamber acts on the valve head and flow o-f fuel occur~
into the bore occupied by the pumping p~unger. The flow
of fuel into the bore continues until the moYem~nt of the
plunger is halted ei-ther b~ the stop ring 25 or earlier
as will be e~plained. ~s soon as movement o~ the plunger
23 is halted no further fuel can flow into tha bore and
the fluid pressureq acting on the valve member 27 are
equali_ed. As a result the valve member mo~es under the
action of the spring 31 until the head engages the afore-
said edge. The communication of the port~ 33 with the
bore is therefore broken.
An electromagnetic device is provided for effecting
movement of the piston 23. ~lis movement is achieved
through the push rod 26 which Qxtends with clearance through
a drilling34~formed in a core member 35 conveniently formed
integrally with the housing 19. The core m0mber extends
on the opposite side of the housing to the first boss
portion 110 The core member is formed from magnetisable
material and therefore in the present construction 50 i~
the h~using 10. It will be appreciated however that the
core member and the housing may be formad as separate part~q.
The core member is of generally truncated conical
configuration and it is provided with a plurality of
circumferentially extending grooves 36. The grooves 36
define circumferentially extending ribs 37 and it will
be noted that the further a particular rib is from the
housing 10 the smal~er i~ its di~meter. ~oreover, this
also applies to the depth of the grooves 36 and in general
the width of the grooves increases as ths distance from
the housing 10 increases.
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The outer surface of the ribs 37 are inclined to the
axis of the core member a~d located within each groove i5
a winding 38. The ~indings con~eniently are connected in
series in such a fashion that when electric current is
passed through the winding~ the direction of current fl~w
in adjac~nt windings is in th0 oppo~ite dir0ction. In thi 3
manner adjacent ribs 37 ~hen electric current is passed
through the windings 9 will be magnetiQed to oppo~it~
magnetic polarity. Conveniently on~ end of the ~eries
connected windings is connected to the oors member whilst
the other end of the series connect~d windings is led
out to a terminal which i~ carried by an electrically
insulating block 4O which is sccured to the housing 10 as
shown in Figure 3.
Surrounding the c~re member is an armature 41~ This
is also formed from magnetisable material and ha9 a thin
saction. The armature 41 can be regarded as a number of
hoops of reducing diameter connected together by inclined
portions such a.q shown at 4~ the internal fa~es o~ the
inclined portion~ l~ing subst~.ntially parallel to the
aforesaid faces of the ribs 37'. The armature is of cup-
shaped form and the base wall is pro~ided with a pair of
~pertures 43 and a oentral aperture which receives a plug
44 in which is located the remote end of the push rod 26,
In use) when the windings are Qupplied with electric current;
the armature will mo~e downwardl~ as shown in the drawing~
to reduca the reluctance of the air gaps betwesn the ribs
and the inclined portions 42 of the armature, In so doing
movement will be imparted to the pumping plunger 23.
;
SurroundIng the armature is a hollow cup shap~d cover
45 which is formed from non-magnetic material conveniently as
a die ca~ting from a ~.inc based alloy~ As will be seen
frcm the dra~ing the cover has a stepped outer peripheral
surface and the sides thereof taper to permit its tiith-
drawal *rom the die cavity~ Th0 internal peripheral surface
is also of stspped form and is shaped as will be described~
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to support the armature for axial mo~ement. Tha end
portion of the co~er that i9 to say in g~neral that portion
~xtending between ths aforesaid external step which is
refsrenced 46 and the housing 10, is formed with four
internal rib~ 47 and defined between these ribs are rec2sses~
As explained in order to p~rmit the c~sting to ba removed
from the die, the internal surfaces are tapered. Aft2r
removal from the die cavity~ the ribs 47 are machined so
as to define ~qurfaces which extend parallel to the axis
o~ the core member. As a result four bearing surface~ 48
are formèd which are engaged by the arm~ture at it~ wider
end~
The co~2r is provided with four further ribs 49 and
again when manufactured these ar0 tapsred to permit removal
of the ca~ting from the die. Subsequently the internal
surfaces of the ribs 49 are machined to provide bearing
surfaces 50 engaging with oomplementary surfaces of the
armature nearer the narrow end thereof. rne space defined
within the cover 35 is connected to a fuel inlet 52 formed
in the boss 12 and in use~ fue:L can flow upwardly on the
inside or the outqida of the a;~ature through the apertures
43 if it has flowed upwardly on the out~ide of the armature,
and down the drilling 34-to the bore 1; in the housing. Thus-
cooling of the windings i9 achieved by the fuel. The pump~
injector is retained in position witnin the bore in the
cylinder head by means of a clamping ring 53 ~hich is in
engagam~nt with the step 46 on the cover. ~ne clamping ring
is provided with a pair of ears in which are loeated
apertures through which extend in use~ threaded studs seoured
within apertures formed in the cylinder head of the engi~e.
A pair of nuts 54 are engaged with the studs. One ~tud is
shown in dotted outline in Figure 2.
The amount o~ fuel which i~ deli~ered through the nozæle
depends upon ths position of the plunger 23 at the end of the
filling strokeO This aq shown in Figure 1, is deter~in~d b~
means of an adjustable stop member in the form of a cam 54
~L2~ 5
which i9 cRrried upon a shaft supported for angular moVQment
within the cover 45~ The cam is engageable by the plug 44
of the armature 419 and connected to the shaft is a lever
55 whiGh is coupled to a linkage 56 which is also connected
to the respective levers 55 of the remaining pump/injectors.
Ths linkage 56 is coupled to one end of a further pi~oted
le~er 57 the other end of which is provided with a spherical
end located between a piston 58 and an abutm~nt 59. The
piqton and abutment are qlidable within a cylinder 60, the
abutment being spring loaded by a coiled compression spring
61. The end of the cylinder containing the spring commun-
icates with a drain whilst the other end of the cylinder
communicates with the outlet of a pump61- which draws liquid
conveniently fuel9 fxom a tank 62. In the example the tank
contain~ fue an~ the outlet o~ the pump i~ connected to the
fuel inlets 52 of the indi~idual pump/injectors. The output
pressure of the pump is contro:Lled by a relief valve 63 and
connected between the outlet of the pump and the c~linder 60
is a control valve 64, A point downstream of the valve 64
is connscted by way of a restrictor 65 to drain. The valve
64 i9 electrically controlled l~nd by reducing the degree of
restriction offered by the valve so the pre~ure applied to
the piston 58 is increased. A3 ths pres~ure applied to the
piston 5~ increases the le~er 57, and the linkage 56 and the
levsrs 55 move the cam 54 to allow the armature and plunger
23 to move further outwardly. In other words the effecti~e
~troke of the plungar at the next stroke i~ increased and so
an increased quantity of fuel will be suppliad through the
nozzle. Conver~ely, if the pressure applied to the piston
58 is reduced then the stroke of the plunger i5 reduced.
The valve 64 is controlled by a control system 66 which
also acts as 2n engine governor, The system is supplied with
a demand signal along a line 67 a~d with signals indicative
of the position of the rotating ~rts of the engine along a
line 68. Signals are supplied by the control systel~ to the
windings of the pump/injectors to ensure that the latter are
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operated in timed relationship with the engine. The controL
system 66 is also provided with a signal indicative of the
setting of the cams 54 by means of a transducer 69 which
comprises a winding 70 ~ound upon a former surrounding the
abutment 59. The latter varies the inductance of the winding
70, by its movement and the ~ignal supplied to the control
system is used in the control system to ensure that the ~et-
ting of the valve 64 i~ adjusted so that the correct quantity
of fuel is supplied to the engine appropriate for the par-
ticular desired and actual engine operating conditions.
Whilst a hydraulic actua~ing mechanism has been des-
cribed for the purpose of adjusting the linkage and the
cams it l~ill be appreciated that other forms of actuating
mechanism could be used for example, an electrical motor
or a pneumatic device.
