Note: Descriptions are shown in the official language in which they were submitted.
1049845
This invention relates to fuel pumping apparatus
for supplying fuel to a supercharged internal combustion
engine and of the kind comprising a plunger reciprocable
with a bore, pump means for supplying fuel under pressure
to said bore to urge the plunger in an outward direction,
control means for determining the quantity of fuel supp-
lied to said bore by said pump means, a cam for imparting
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inward movement to the plunger to displace fuel from said
bore through an outlet and stop means for determining the
~; 10 maximum outward movement of the plunger irrespective of
the setting of said control means.
When such apparatus is utili~ed to supply fuel to
a supercharged engine it is necessary to provide at least
two levels of maximum fuel to ensure that under all condi-
tions of operation the level of smoke in the exhaust of the
engine is no more than is allowed by the various regulations
, in force. With a supercharged engine and particularly when
'~ the supercharger is of the type which includes a turbine
driven by the exhaust of the engine, the degree of super-
charging at low engine speeds is such that the engine can
for all practical purposes be regarded as a "naturally asp-
- irated" engine. -
.
As the engine speed increases the supercharger bec- ~;
omes effective and a greater mass of air is delivered to the
engine combustion spaces. The level of maximum fue~l can there-
fore be increased as the supercharger becomes more effective.
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104~845
It is however necessary to ensure that the apparatus can
provide an excess of fuel for starting purposes the level
of excess fuel usually being greater than the level when
the supercharger is providing the maximum pressure.
The object of the invention is to provide an apparatus
of the kind specified which is capable of providing two levels
of maximum fuel in addition to excess fuel for starting purposes.
According to the invention in an apparatus of the kind
specified said stop means comprises a stop member movable in a
direction at right angles to the axis of movement of the plunger,
first and second members, each of said first and second members
being independantly adjustable to determine the position of said
stop member, means coupled to one of said members for positioning
said one member so that an excess of fuel will be supplied by the
apparatus for starting purposes, and air pressure responsive means
coupled to the other of said members, said air pressure responsive
means in use, being subjected to the pressure of air developed by `~
the supercharger of the engine whereby the other of said members
will be positioned to provide at least two levels of maximum fuel.
According to a further feature of the invention said other
member is movable in said direction and its movement is impar~ed
through said one member to said stop member.
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In the accompanying drawings:-
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104~845
Figure 1 is a sectional side elevation of one example
of an apparatus in accordance with the invention,
Figure 2 is a section at one axial position of the
apparatus,
Figure 3 is a side view showing two co-operating parts of
the apparatus,
: Figure 4 is a perspective of two further parts of the
apparatus,
Figure 5 is a view similar to Figure 2 with the section
: 10 taken at another axial position and,
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Figure 6 is a view showing to an enlarged scale, a
modiication of part of the apparatus of Figure 2.
Referring to the drawings the apparatus comprises a
housing 110 in which is located a rotary cylindrical distributor :.
member 111 which is coupled to a drive shaft 112 which extends
: from the body part and is adapted to be driven in time
relationship with a supercharged engine with which the apparatus
is associated.
Formed in the distributor member is a transversely
extending bore 113 in which is mounted a pair of reciprocable
pumping plunger 114. Communicating with the bore 113 and
extending longitudinally within the distributor member is a
passage 115 which at one point communicates with a radially
disposed delivery passage ~not shown) which is adapted to
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1049845
register in turn as the distributor member rotates, with a
plurality of outlet ports 116 formed in the housing. ~he outlet
ports in use are connected to fuel injection nozzles disposed to
direct fuel into the combustion spaces of the associated engine.
At another point the passage 115 communicates with radially
disposed inlet passages 117 which are able to register in turn
as the distributor member rotates, with an inlet port 118 formed
in the housing. The inlet port 118 communicates with a supply
passage 119 by way of an angularly adjustable throttle member 120
., .
and when the inlet port communicates with the passage 117 fuel
will flow from the supply passage 119 to the bore 113. The amount
of fuel which can flow when such communication is established,
depends on the setting of the throttle member 120. In known
manner the setting of the throttle member 120 is controlled by a
governor mechanism which includes a plurality of weights 121
movable outwardly to decrease the amount of fuel supplied, the
weights moving in opposition to a governor spring (not shown) the
force exerted by which can be adjusted by means of an operator
adjustable member tnot shown).
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The supply passage 119 communicates with the outlet of a
feed pump (not shown) which draws fuel from an inlet 122 and the
outlet pressure of the feed pump is controlled in known manner,
by means of a valve (not shown).
At their outer ends the plungers 114 contact shoes 123 which
support rollers 724 respectively. The rollers 124 engage with the
internal peripheral surface of a cam ring 125 which is angularly
adjustable within the housing. The cam ring has on its internal
1049845
peripheral surface, a plurality of pairs of cam lobes. The
rollers 124 and the shoes 123 rotate with the distributor member
111 and as the rollers engage the cam lobes inward movement will
be imparted to the plungers 114. During this movement fuel is
displaced from the bore 113 and flows by way of the passage 115,
to one of the outlet ports 116. When the rollers 124 move over
the cam lobes the plungers 114 can move outwardly under the action
of fuel which is supplied by way of the inlet port 118, the fuel
flowing to the passage 115 by way of one of the inlet passages
117.
The angular setting of the cam ring 125 is adjustable in
known manner, by means of a fluid pressure operable piston 126
which is contained within a housing 127, the piston being
connected by means of a peg 128 to the cam ring. Fuel under
pressure is applied to the piston 126 by way of a passage 129
which communicates with the passage 119.
'
In order to control the quantity of smoke in the exhaust
system of the engine it is necessary to limit the maximum amount
of fuel which can be supplied by the apparatus under normal
operation but it is also necessary to aIlow the apparatus to
provide an additional or excess quantity of fuel to enable the
associated engine to be started particularly when it is cold.
Moreover, since the engine is a supercharged engine the amount of
fuel which can be supplied to the engine depends upon the pressure
of air delivered to the engine by the supercharger. S4p means
is therefore provided to control the permitted outward movement of
the rollers lZ4 and thereby the shoes 123 and the plungers 114.
.
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104984S
The end portions of the rollers 124 ars tapered and ~.ount~d
on opposite sides of the rollers ar~ a pair of stop rings 130.
The stop rings are positioned outwardly of the rollcrs and arc
shaped for en~a~ement with tho end portions of the rollers. As
seen in ~igure l of thc drawings, the ri~ht-hand stop rlng is
fixed within the housing however7 thc left-hand stop ring is set
into an annular member 131. The annular member 131 is angularly
adjustable as will be described.
The face of the annular member 131 remote from the rollers
is engaged by the end face of a ring member 133 and this is
secured against angular movement within the housing by means of
a stop 132 engageable within a slot defined within the ring member
The peripheral surface of the ring member 133 is provided ~ith a
screw thread which is in engagement with a complimentary screw
thread formed on the internal periphery of a further ring member
134 and the outer peripheral surface of the ~urther ring member is
prov;ded with gear teeth engaged by a worm adjustor 135. The
angular setting of the adjustor 135 may be determined from
exterior of the body part in a manner to be described, ~s the
adjustor 135 is rotated the further ring member ].34 will partake
Or angular movement and by virtue of the screw threaded connection
between the ring members 133 and 134, the ring member 133 will
move axially. Such axial movement will be imparted to the annular
member 131 and by this arrangement the amount by which the ~ollers
124 can move outwardly can be determined. ~or practical purposes
the an~ular setting of the adjustor 135 will be preset when the
pump is assembled but it may be reset as and when required.
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~049~345
m e adjustor 135 is also axially movable and such morement
also has the effect of causing angular movement of the ring member
134 and therefore axial movement of the ring member 133. As
shown in Figure 5 the adjustor 135 has connected thereto a
cylindrical rod 150 which is guided for axial movement in a bore
formed in an angularly adjustable body 151 mounted in a recess in
the housing 110. The end of the rod remote from the adjustor
extends into a cavity defined in the body 151 and is also screw
threaded.
Slidable within the cavity is a plug member 152 which is in
adjustable screw thread engagement with the rod 150 and the plug
member is biased in the direction out of the cavity by means of a
coiled compression spring 153. The extent of movement of the plug
member against the action of the spring 153 is limited by a flange
formed on the plug member and which engages with the end face of
the body 151. The plug member is engaged by a flexible diaphragm
154 which forms an end wall of a chamber 155 to which air under
pressure can be admitted through an inlet 156 from the inlet
manifold of the engine. m e diaphragm in fact forms a division
wall between a pair of cup shaped parts 157 and 158, the part
158 being secured to the body and the part 157 carrying the inlet.
The body 151 is retained in the housing 110 by means of a
hinged plate 159 which locates within a circumferential recess in
the body and interposed between a step on the body and a washer
bearing on the plate is a coiled compression spring which acts to
resist angular movement of the body within the housing. When
adjustment is completed as will be described, the body is secured
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: 104984S
against rotation by means of a security wire. The end of the
body 151 is provided with a pair of diametrically disposed slots
the walls of which engage flats formed on the adjustor 135 and
in this manner angular movement of the body will impart angular
movement to the adjustor 135. When the engine is at rest the
spring 153 will urge the plug 152 together with the rod 150 and
adjustor 135 upwardly to the position in which the adjustor
engages the body. The body is then moved angulaxly to obtain a
maximum fuel setting which is appropriate for the operating range
of the engine in which the output pressure of the supercharger
is such that the engine can be regarded as being "naturally
aspirated."
In use when air under pressure is supplied to the chamber
155 the extent of movement of the adjustor will be determined by
the abutment of the flange on the plug with the body. The range
of movement and therefore the increase in the maximum amount of
fuel, is adjusted by altering the amount by which the rod 150
is screwed into the plug. once this setting has been made the
threads can be locked together with a proprietory locking compound.
The pressure of air required to effect movement of the adjustor is
determined by the pre-load of the spring 153.
In order to provide an excess of fuel for staring purposes
it is clearly necessary to allow further separation of the stop
rings 130. For this purpose the ring member 133 is provided'with ,,
a plurality of concave recesses 136, in its face presented to
the annular member 131. One such recess is seen in Figure 3.
Moreover, the annular member 131 is provided with complimentary
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104~8~S
projecti~n~ 137 ~d during norm~l operation of the apparatus the
projections 137 engage the end face of the ring memb~r 133 ~s is
shown ln ~igure 3. When an excess of fuel i5 required for startin8
purposes the annu].~r me!nber 131 is moved angularly so as to bring
the projections 137 into register with the recesses 136. Wh.en this
occurs the main body portions of ths annular member and the ring
' member can move closer together thereby allowing ~ncre2sed
separation of-tho stop rings 130 so that the plungers 124 can move
an additional amount in the outward direction.
Movement of the annular member 131 is ~cilieved by means Or
a second adjustment means generally indicated at 136a in E`igure
Z. The second adjustment means comprise-s a piston 137 which is
,slidable within a cylinder 138. The piston is connected by mean~
of a pin 139A to the annular member and is biased by means of a
' ,spring 139 contained in one end of the cylinder 138. At the oth~r
end of the cylinder 138 is an angularly adjustable membor 140 wllich
contains a fuel supply passage 141 and which is connected to the
fuel supply passage 119. A valve 142 is provided to control the
~low of fuel into the cylinder 13~. Moreover, the angularly
movable member 140 and the piston 137 are provided with inter-
engageable members whereby movement of the piston 137 under the :
action of its spring 13g is prevented until the member 140 is
moved angularly. In the particular example the member 140 is
provided with a tongue 143 engageable with a recess 144 formèd in
the piqton and the member 140 is biased by means of a spring 145
to a position in which the tongue 143 is out of alig~nent with .
the reces~ 144. . :
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1049845
When an ~xcess of fuel is required for ~arting purposes
the melnber 140 is moved angularly against the action of the
spring 1~5 to bring the tongue 143 into register with the
recess 144 and when ~his occurs the piston 137 moves ~der
the action of the spring 139 thereby moving the annular mem
ber 131 angularly and bringing the projections 137 into reg-
ister with the recesses 136, l~'hen this occurs the annular
member 131 will be forced in an axi.al direction by the force
actirg on the rollers 124 and deve~p~d by the fuel pressure
acting on the plungers 114. In this manner an excess of
fuel is supplied for starting purposes.
.
The action of the valve 142 is to delay the application
of fuel pressure to the piston 137 until the speed of the
associated engine has built up. ~nce the valve 142 is lifted
~rom its seating then fuel pressure acts on the piston and the
latter is moved to the position shown in Figure 2. In this
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position the normal rnaximum amount of fuel is supplied to the
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engine. The valve 142 comprises a ball which is urged into :.
contact with a seating defined on the angularly adjustable
member 140, The ball is loaded by means of a coiled compression ~:~
spring positioned between the ball and the piston 137. By this :~
arrangement the initial pressure required to open the valve is
higher than the pressure at which it will close because once
the piston has moved then the force exerted by the spring which
loads the ball is reduced. The practical effect of this arrange-
ment is that excess fuel will be supplied by the apparatus until
the engine attains a speed greater than its normal idling speed
but even ir the tongue and groo~ are maintained in alignment
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10491345
excess fuel will not be obtained until the engine spe~d
- has dropped well below its normal idling speed.
It wil7 be noted that when the piston 137 is iIl the
normal maximum fllel position then it is impossible to obtain
excess fuel by rotating the angularly adjustab1e member 140.
/To enable angular adjustment of the member 140 to be effected,
it is provided with a plate 146 which carries an offset pin
147 which can be connected to a driver operable linkage
(not shown),
.
In some instances it is desirable to ensure that the
timing of delivery of fùel to the engine is retarded during the
delivery of the excess of fuel. This effect can be obtained by
causing the piston 137 to act as a valve, As sho~m in ~igure 2
a passage 149 is provided which comml~icates with the outlet
119 of the feed pump. In addition a further passage 148 is
provi~ed which when it is desired to retard the injection of
fuel~ acts to convey fuel under pressure to the passage 129~ the
direct connection o~ the passage 129 with the outlet 119 of the
feed pump being broken, The passage 148 communicates wi~h the
cylinder 138 at a position such that it will be covered by the
piston 137 when the piston is in the position Ruch that excess
fuel is supplied~ the passage being uneovered when the piston
moves to its normal fuel position.
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With the arrangements described the maximum amount of
fuel which can be supplied by the apparatus has at least two
levels for normal operation of the engine and in addition excess ~-
fuel can be obtained for startingr purposesO
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104~i845
It will be noted that the ball forming the valve 142 isloaded by a spring into contact with its seatln~. A~ a reRult
the movement of the pis'on 137 when exces~ fuel '~ selected, will
be 810w ~ince the fuel displaced by the piston can only escape
by leakage. This can in praetical terms be a nuisance becauss
if for example, the engine is started ~rom cold and runs up to a
speed at which the ~upply of exces~ fuel cea~es and then stalls,
there is a delay before exceos fuel is again obtained.
; This difficulty can be o~ercome by the modified cons-
truction shown in Figure 6. In Figure 6 the piston 1~0 replaces the
piston 137 and the member 161 and the member 140. The member 161 is
-~ provided with a ton~ue not shown which can locate in a groove in the
pi~ton, the tongue and groove being engaged in the position Or the
parts shown in Figure 6. The valve however i8 different and it is
a normally open val~e with a ball 162 biased away ~rom its seating ~-
by a light spring, the extent of movement being limited by a stop plate
ha~ing a non-circular aperture. Moreover, the piston 160 i~ provided
with an abutment 163 which engagee w~th the ball when the piston i~ in
the posltion corre3ponding to excess ~uel, to hold the ball in contact
with the seating.
.:
In use~ with the ball in thè cto~ed po~ition the fuel
pres~ure acts only upon the ball and therefore the pre~sure must rise
to a considerable value before the force exerted on the ball is
~u~ficient to li~t the ball from the seating against the action o~
the spring biasing the piPton. ~nce the ballhae lifted then the
~uel preesure ac~s upon the pieton and the lat~er 1B mo~ed its
maximum extent and w~ll remain in thi~ position even if the engine
~peed ~all~ to ~ling speed.
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1049~145
When the engine stops tlle piston can return quickly to the
position shown providing the tongue is aligned with the groove~
because the ball is held away from its seati.ng, Thus excess fuel
can be obtained quickly. As the valve is moved into the sea~in~
the movement of the piston could be restricted however, this is
overcome by arranging for t.he piston to open a le~kage path ~rom
the space between the piston and the member 161. As shown in
Figure 6 the leakage path comprises a groove 164 extending towards
the head of the piston and which communicates with a port 165 in
the wall of the cylinder containing the piston as the ball is moved
onto its seating. The port 165 communicates with the aforesaid
space,
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