Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2~
LIQUID PUMP
This invention relates to liquid pumps, particularly
liquid pumps usable for pumping fuel, such as in petrol
injection systems of internal combustion engines.
According to the present invention there is provided a
liquid pump comprising pump means having a plurality of
pistons and cylinders arranged around a rotatable drive-
shaft defining a central axis, inlet means for admitting
liquid to the cylinders and outlet means for receiving
liquid therefrom under action of reciprocation of the
pistons, said outlet means including flow restriction
means, eccentric means comprising a cam member eccentric-
ally rotatable with the driveshaft and an orbital body
mounted on the cam member so as to execute an orbiting
motion to effect said reciprocation during eccentric
rotation of the cam member, said orbital body having a
plurality of faces a separate one of which is arranged to
impart said reciprocation to a .respective one of the
pistons, said cam member being linearly slidable relative
to the driveshaft and transversely of the central axis
between a position of maximum eccentricity and a position
of reduced eccentricity thereby to adjust the orbital
motion of the orbiting body between a condition of maxi-
mum reciprocation of the pistons and a condition of reduced
reciprocation of the pistons, and means biasing the cam
member in a direction towards said position of maximum
eccentricity whereby under relatively.low pressure cond-
itions in the outlet means said maximum condition of recip-
rocation is maintained so as to.pump a maximum volume of
liquid and under relatively high pressure conditions in
the outlet means due to said flow restriction means
pressure in a cylinder open to said outlet means is capable
of acting on the orbital body through the respective
piston and associated flat ~ace and thereby on the cam
member in the opposite direction against the tendency of
the biasing means to automatically reduce the eccentricity
and the reciprocation of the pistons so that a reduced
flow of liquid is pumped.
7S8
Preferably, the orbital body has four flat faces and a
respective piston and cylinder is associated with each
flat face.
The pump means may comprise a second pump means, and
first pump means is also provided, the first pump means
being operable to pump liquid admitted to the liquid
pump, under pressure, to the second pump means, the
second pump means being operable to deliver pressurised
liquid therefrom to liquid delivery means of the liquid
pump.
The first pump means may comprise a gear pump or other
positiva displacement pump operable to pressurise a
gallery from which gallery fuel is in use admitted to
the second pump means.
The aforementioned gallery may be provided with
overflow means permitting restricted outflow of liquid
from said gallery.
The liquid pump may include a liquid metering device
connected for metering liquid delivery ~rom the pump
means, saîd liquid metering device comprising a first
member having a space therein and a second cylindrical
member in said space, said members being mounted for
relative rotation one relative to the other, said first
member having first port means for admission of liquid
to said space and second port means for outflow of
liquid thererom, said second member having a first
transer cavity therein which, at a condition of
alignment of said first port means occurring during
relative rotation of the members, can receive liquid
from said first port means, and transfer means being
provided for then delivering at least a part of the so
received liquid
58
from said transfer cavity to said second port means
when, ~hereafter during said relative rotation, a
condition of alignment occurs between said transfer
cavity and said second port me~ns. Preferably, said
members are relatively rotatable about a common axis,
and said transfer means comprises an element carried
by said second member and movable axially of said
f irst and second members and being arranged to extend
into said transfer cavity t~ displace liquid thexefrom
1~ to said second port means. Preferably, the liquid
metering device includes third port means in said
first member arranged for delivery of liquid into a
second transfer cavity in said second member, said
element being arranged to extend into said second
transfer cavity whereby to be acted on by liquid flow
from said third port means into said second cavity for
moving the said element to effect said displacement of
liquid in the first transfer cavity. Preferably too,
the liquid metering device includes fourth port means
in said first member and arranged whereby to receive
liquid from the said second transfer cavity when the
second transfer cavity is aligned with said fourth
port mea~, said first, second, third and fourth port
means being arranged.whereby, during sa~d relative
rotation of said members, admission of said liquid
from said first port means to said first transfer
cavity causes a portion of said element then within
said first transfer cavity to be acted on by liquid
pressure to move said element to displace liquid from
~aid second transfer cavity to said fourth port means,
whereby displacement of liquid from said first and
second transer cavities to said second and
fourth ports respectively is effected by oppositely
~ ~6~3758
( directed reciprocating movements of said element under
admission of liquid to the respective second and first
cavities. Preferably, means is provided for varying
the stroke of said element during said reciprocatory
movements whereby to vary the ~mount of liquid
displaced from the said cavities to the second and
fourth ports in use. Preferably too, for the purpose
of varying the angular positions at which said
displacement occurs, during each complete relative
revolutionary movement between the first and second
members, variable displacem~nt means i~ provided for
relatively variably displacing the first and second members
about the axis of the second member whereby to vary the
relative positions of the transfer cavity or cavities and
associated ports. Preferably the variable displacement means
comprises means sensitive to pressure derived from said pump
means, whereby to effect such variable displacement, in
accordance with that pressure, in a direction tending to
relatively advance the times during each revolution of said
second member at which displacement of liquid from the
said transfer cavities is effected. The said
pressure may be the delivery pressure of said first
pump means or of said second pump means but is
preferably the pressure of liquid at the outlet of
said first pump means and said advance is preferably
arranged to occur when said pressure of liquid at the
outlet of said first pump means rises.
The above described arrangement for advancing the
relative angular positions at which liquid
displacement occurs has an advantage where the liquid
pump is a fuel pump operated from an engine in that
~26~)7'~
the pressure of liquid fuel delivery from the
aforementioned first pump means, where this is a
positive displacement pump, whilst being primarily
dependant on speed of rotation of the drive thereto and
thus on the speed of rotation of the internal
combustion engine which in use drives the gear pump,
may also be made to be in part influenced by load on
the engine. More particularly, under heavy load the
liquid pump can be arranged to deliver, from the second
pump means, a greater quantity of liquid fuel than is
the case where the engine runs under low load
conditions. As a result, for constant speed running,
the output pressure from the first pump means will be
dependent on engine load, decreasing with increase in
load. Thus, under heavy load, there will be a
secondary effect on the aforementioned varying of the
times of delivery from the liquid pump so that under
high load conditions there will be a relative angular
retardation of the position during each relative
revolution of the first and second members at which
fuel delivery occurs.
Where the pump with which said liquid metering device
is used as a fuel pump for an internal combustion
engine, the said means for var~ing the volume of
delivered fuel is preferably arranged so as to be
coupled, in use, to an output regulating device such as
the accelerator where the engine is intended ~or
coupling for driving a vehicle.
Thus, in accordance with a still further aspect of the
invention there is provided a liquid pump as first
above described, including the first and second pump
means wherein said first pump means is
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adapted to provide an output liquid delivery rate
therefrom which is dependent on the speed at which the
first pump means is driven, said second pump means
being adapted to cause said delivery pressure from the
first pump means to be lowered under conditions of
high flow from the liquid pump; said liquid pump
having delivery means for periodically delivering
liquid from the second pump means at predetermined
times during operating cycles of period inversely
proportional to said speed, and means responsive to
delivery pressure from the first pump means to vary
the ratio of a time interval to the said period of a
said cycle, said time interval being the interval
measured from initiation of that said cycle to the
time at which said delivery occurs in that said cycle.
In another preferred aspect of the invention, a
pressure sensitive valve is provided sensiti~e to the
output pressure from said second pump means and
operable to return liquid delivered from said second
pump means to a liquid supply to the first pump means
under the condition that the pressure exceeds a
predetermined value.
The invention is further described with reference to
the accompanying drawings in which:
Figure 1 is a schematic view of a fuel supply system
including a pump constructed in aacordance with the
invention;
Figure 2 is formed in two parts 2a and 2b which join
on the line "X-X" shown to form an axial cross-section
30 Of the pump of figure 1
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9 ~0~758
Figures 3a and 3b are diagrammatic scrap
cross-sections substantially on the line 3-3 in
Figure 2, but showing two different conditions of two
cooperating parts of the pump of Figure 2;
Figure 4 is a cross-section on the line 4-4 in Figure
2;
Figures 5 to 16 inclusive are diagrammatic cross-
sections illustrating the manner of operation of fuel
metering means incorporated into the pump of Figure 2
and in which Figures 5, 8, 11 and 14 are cross-
sections on the line 5-5 in Figure 2, Figures 6, 9,
12 and 15 are cross-sections on the lines 6-6 in
Figure 2 and Figures 7, 10, 13 and 16 are
cross-sections on the line 7-7 of Figure 2, and which
Figures 5 to 7 inclusive show conditions prevailing
at a condition of zero rotational displacement
between two members of the metering means, Figures 8
to 10 inclusive show condition of 90 phase
displacement between those members, Figures 11 to 13
show condition of 180 phase displacement between the
members, and Figures 14 to 16 show a condition of
270 phase displacement between the members;
Figure 17 is a scrap cross-section showing a valve
associated with one cylinder of a high pressure pump
stage incorporated into the pump of Figure 2, being a
view taken approximately on the line 17-17 in Figure
4.
Referring firstly to Figure 1, the fuel supply system
shown therein generally comprises a fuel tank 10, a
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subsidiary fuel pump 12 and a main fuel pump 14. The
fuel pump 12 is connected via a line 15 to the tank 10
and operates to supply fuel at low pressure to the
pump 14 via a filter 16. The fuel line 18 from filter
16 is connected to an inlet gallery 20 forming part of
pump 14. Fuel so-delivered to the gallery 20 is fed
via an inlet 22 to a gear pump 24 also forming part
of fuel pump 14. Gear pump 24 in turn supplies fuel
to a low pressure gallery 26 formed in the body of
pump 14. From gallery 26, fuel is fed to a high
pressure pump 28 via a drilled gallery 30. Output
from pump 28 is fed to two fuel distributors 32, 34
via a branched fuel gallery 36.
r~he pump 14 is intended to pump liquid fuel such as
petrolaum which, ~n its lighter spirits, has a
tend~ncy to vaporise easily. A bleed choke line 38 is
provided from gallery 26, via which a small amount of
fuel in the gallery 26 can be returned back to the
tank 10 continuously. This return i8 arranged at the
highest point in the gallery 26 and serves to assist
in removal of any gasified fuel or trapped air from
the gallery 26.
The gear pump 24 is a positive displacement pump of
conventional kind and operates to deliver a quantity
of fuel to gallery 26 which is proportional to the
speed of rotation thereof. Both the gear pump 24 and
the pump 28 are, as described in more detail later,
driven by an internal combustion engine ~not shown)
with which the pump 14 is in use associated so that as
engine speed increases so will the speed of the pump
24 and so will the pressure of fuel delivered to
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gallery ~6. A certain amount of fuel so-delivered is
taken off by pump 28, but a relief line 35 is provided
connected to gallery 30 and including a restricting choke
40 which serves to deliver, back to the inlet gallery
20, fuel from the gallery 26 where insufficient fuel
has been taken via gallery 30 to pump 28 to ~aintain
the fuel pressure in the gallery 26 at below a
predetermined maximum value established by the orifice
size of the choke 40. A pressure release valve 46 is
also connected to ~he gallery 36 from ~he pump 28 to
distributors 32, 34 and this is set to open under
predetermined pressure conditions in gallery 36
whereby to deliver, via a gallery 48, fuel from the
gallery 36 back to the gallery 20. Thus, lf
insuf ficient fuel is being delivered from the
distributors 32, 34 so that pressure in gallery 36 is
beyond the preset pressure of opera~ion for the relief
valve 46, that pressure is relieved by fuel flow via
the valve 46 and gallery 48 back to the inlet gallery
20. Excess fuel from the distributors 32, 34 and
which may, by leakage of components therein, not be
presented to outlets there.from~ is returned via
interior housings and shafts of the pump 14 ~not shown
in figure 1) which communicate with a branched line 50
to the gallery 20,
Generally, the pump 28 serves to raise the operating
pressure of fuel admitted thereto to sufficient
pressure for operation of fuel injectors 52,54 and the
distributors 32 and 34 operate to distribute the
so-pressurised fuel ~o the in~ectors. The particular
pump described here is adap~ed for use in a en~ine of
the kind descrlbed in Canadian patent 1,104,444
12~ )7~3
particularly being an engine in which there are two
fuel injectors for each cylinder of the engine.
Distributor 34 serves to supply fuel to the injectors
52 each of which supplies fu~l at one location for
each engine cylinder, whilst distributor 32 operates
to distribute fuel to the injectors 54, each of which
is arranged to supply fuel at another location for
each cylinder. The arrangement of the engine
described in the aforementioned patent is such that
the distributor 34 need only supply fixed volumes of
fuel to the injectors 52 regardless of engîne speed or
load, the injectors 52 being arranged to inject uel
into small subsidiary combustion chambers in which
ignition of fuel is first effected in each cylinder of
the engine. On the other hand, the injectors 54 are
required to be provided with quantities of fuel which
are dependent on engine load, since these injections
are associated with main combustion chambers of each
cylinder of the engine, which main combustion chambers
are arranged so that ignition of fuel therein is
; caused by contact with igniting fuel charges from the
aforementioned auxiliary combustion chambers.
Tuxning now to Figure 2, the pump 14 is shown in more
detail as including an inlet shaft 56 which drives
both of the component pumps 24 and 28 of the pump 14.
Pump 24 includes two meshing gears 82, 84 of which
gear 84 is drivingly coupled to shaft 56 and gear 82
is drivingly coupled to a shaft 90 parallel to shaft
56. Both shafts 90 and 56 are journalled for free
rotation in a housing 80 of the pump. The gears 82,
84 run in a generally ~8"-shaped cavity 92 in the
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9-2~i0~58
housing 80, opposed faces of which sealingly engage
side faces of the gears 82,84. The gallery 20 is
indicated in figure 2, this communicating with the
cavity 92 ~t a location adjacent the nip between the
two gears 82, 84 but to one side of the nip when
viewed parallel to the axes of the gears. Fuel
supplied to the gallery 20 is passed to this nip and
passes through the cavity 92 around the peripheries of
the gears 82, 84 in the cavities between adjacent
teeth of the gears, as the gears rotate pursuant to
driving of shaft 56. Fuel so passing around the gears
is delivered to gallery 26, which gallery communicates
with the cavity 92 at a location adjacent the nip
between gears 82, 84, but at the opposite side of that
nip to the location where the gallery 20 communicates
with cavity 92.
As shown in figure 4, the pump 28 includes four
pistons 98 arrayed in an equiangular array about the
axis of shaft 56. These are lengthwise reciprocable
in radial cylinders 106 retained in housing 80. At
innermost ends, the pistons have convex bases 115 with
outwardly extending flanges 114, and these bases 115
rest on the interiox surfaces of bases 116a of
cup-shaped elements 116. The cup-shaped elements 116
have side wall portions 116b of hollow cyLindrical
form which are slidably mounted in bores 118 ~figure
2) coaxial with the respective pistons 98. Resilient
compression springs 120 are arranged around the outer
surfaces of the cylinders:106 and exert resilient
pressure between outwardly stepped surface portions
122 vn the exteriors of ~he cylinders 106 and the
flanges 114 on the pistons 98, whereby the pistons are
~ X ~ ~75 ~
resiliently biased radially inwardly towards the axis
of the shaft 56. The springs 120 are accommodated
within annular spaces defined between the interior
surfaces of the side wall portions 116b of the
cup-shaped elements 116 and the exterior surfaces of
the cylinders 106.
Flat surfaces of the bases 116a of the elements 116,
closest the axis of the shaft 56, rest upon respective
flat surfaces 124 of a square element ~26. Element
126 has a circular bore 128 therethrough and a
cylindrical cam member 130 having a circular periphery
is neatly accommodated within bore 128 so that the
element 124 is freely rotatable about the member 130.
~he member 130 has an opening 132 therethrough which
is of elongate rectangular transverse cross-section.
This is neatly accommodatPd over a square
cross~sectioned portion 56a of shaft 56 so that member
130 is non-rotatable relative to the shaft 56 but
slidable radially of the shaft 56 in the direction of
the longer dimension of the rectangular cross-section
of opening 132. To either axial side of the element
126 and member 130, there are provided on the shaft 56
two outwardly extending flange members 136, 138.
These flange members have square central apertures
therethrough and these are neatly accommodated over
the portion 56a of shaft 56 whereby the flange members
136, 138 are irrotatable relative to the shaft 56.
Pins 140, of which only one is shown in the drawings,
extend parallel to the axial direction shaft 56 and
through openings in the member 130. Portions of these
pins extend from opposed transverse side faces of the
member 130 to be accommodated in slots 136a, 138a on
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~LZ60758
inner faces of the flange members 136, 138 which slots
are directly opposed to the transverse side faces of
the element 126. The slots 136a, 138a extend in
directions which are parallel to the longer dimension
of the cxoss section of the opening 132 through member
130.
The flange members 136,138 are positioned between, on
the one hand, an outward step 133 in the periphery of
the shaft 56 and, on the other hand, a retaining
element 135 splined onto the shaft 56, and are
precluded from axial movement away from the step 133
by a circlip 137 engaged in a grove in the shaft. The
flange members 136, 138 serve to retain the member 130
and element 126 whilst permitting these to move in the
radial direction of the longer cros~ ~ectional
dimension of the opening 132 in member 130, the latter
movement being accompanied by movement of the ends of
pins 140 in slots 136a, 138a.
The radial sliding movement of the member 130 which is
permitted relative to the axis of shaft 56 permits the
member 130 to be positioned over a range of variable
eccentricities relative to the axis of the shaft 56.
In figures 2 and 4, the member 130 is shown positioned
at a maximum eccentricity at which one shorter side
surface 132a of the rectangular cross-section of the
opening 132 is adjacent one face of the square
cross-sectioned portion 56a of shaft 56. From this
position, the member 130 is movable in the direction
shown by arrow "B" in figure 4 so that the
30 eccentricity is reduced. The minimum eccentricity
permis~ible is established at a condition at which the
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14
other shorter side surface 132b of the opening 132 is
brought into engagement with outer snds of radially
extending pins 148, 150 ~figure 2) received in radial
bores 152, 154 in portion 56a of shaft 56, These pins
rest on basal portions of the bores 152, 154 and
extend therefrom to outer ends thereof which project
somewhat from the portion 56a of shaft 56.
In the inoperative position of the pump 14, the member
130 is biased to a condition of maximum eccentricity
by means of resilient compression springs 160, 162
positioned in the bores 152, 154. Springs 160, 162
rest on outwardly extending lower flanges formed on
the pins 148, 150, and extend around the respective
pins 148, 150 80 as to bear, at outer ends thereof,
15 against the surface 132b of the opening 132.
Under the condition of rotation of the shaft 56, the
eccentric positioning of the member 130 causes the
axis of that member, a~d the aligned axis of the
element 126, to execute a circular orbiting motion
20 around the axis of the shaft 56, the me~ber 130 being
driven positively by virtue of the coupling between
the member and the shaft 56, as provided by the pins
140 and flange members 136, 138, and by the
interengagement of the non-circular opening 132 on the
25 non-circular cross-sectioned poxtion 56a of the shaft
56. Thus, the point of maximum eccentricity on the
outer surface of the member 130 likewise executes a
circular motion about the axis of shaft 56. Element
126 is carried around with member 130, but is
30 generally constrained against bodily rotation about
the axis of shaft 56 by virtue of the four radially
.... .... .
:,.~.. :.:
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126() 7~
directed re~qilient forces applied thereto from the
qprlngs 120 via the elements 116 and by virtue of ~he
sur~aces 124 ~eing flat and enqag~d with th~ fl~t
radi~Lly innenmost surfaces of the bases 116a of
elements 116. Thus, the ecc~ntric rot~t~onal ~ovement
of the element 130 ca~se5 the member 126 to ex~cute an
orbiting motion around ~he axi-q of the shaft 56 while,
at the sam~ time, maintaining the ~ide faces 124
thereof in constant orientations relative to the axes
of the pistons and cylinders o the pump 28. Thus,
the orbiting motion of the element 126, when resolved
along the mutually perpendicular axes of the cylind~rs
106, produces component motions thereof which dr~ve
the pistons 98 so as ~o cause these to execute
reciprocatory motions. Radially outward mo~ions of
the pistons are caused by direct outward component~ of
the movement of the element 1~6 while radially inward
movem~nts are.caused by the springs 120 which, as
me~tioned, resiliently bias the pistons inwardly. The
; motions sf the pis~ons are arranged so that the
reciprocatory motions thereof as executed in use of
~he pump are phase displaced by 90, one with respect
to the preceding one reckoned around the axis of the
shaft 56. In figures 2, one piston 98, that to the
upper side of the shaft 56 as shown, is shown at a
position of ma~Lmum outward reciprocatory motion
whilst ~he opposi~e piston 98 is shown at a positîon
of maxLmum inward movement. At this condition the
rem~ining two pistons 98 occupy intermediate
positions in the reciprocatory mo~ion, as shown in~
Figure 4, which is rotated through 90C relative to
Figure 2~
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16
Fuel from the gallery 26 is supplied to the spaces
between the outer ends of the pistons 98 and the outer
ends of the interiors of cylinders 106 via ports of
which one port only, designated by reference numeral
180 is visible in figure 2, being that port associated
with the uppermost cylinder 106. The ports 180 for
the remaining cylinders are, however, similar, as
shown in figure 4. Likewise, the interconnections
provided by the gallery 30 from th~ gallery 26 to the
pump 28 are not fully shown in figure 2 save that a
portion of the gallery 30 is shown in housing 80, by
broken lines, being that portion which leads from the
lowermost depicted cylinder to the gallery 26. The
gallery 30 is, however, branched so as to deliver fuel
respectively to the four ports 180 associated with the
four cylinders. The ports 180 also act as outlet
ports for the four cylinders and inlet and outlet via
the ports is controlled by respective valves 190. The
valves 190 are similar and the following description
of the valve l90 as shown in figure 17 is to be taken
as being equally applicable to each of the valves 190.
The valve 190 shown comprises an elongate cylindrical
body 189 formed in two parts 192, 194 which are
arranged end to end and sealingly retained within a
bore 196 in the housing 80. The body 189 defines an
elongate central cavity 198 which communicates with
the port 180. The inlet gallery 30 communicates with
one axial end portion 198a of the cavity 198 via an
inlet port 200. A ball 202 in end portion 193a of
30 cavity 198 is resiliently biased by a spring 206 to
normally close port 200. However, under influence of
pressure from the fuel in gallery 30 on a r~dially
inwardly directed stroke of the piston 98 of the
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cylinder 106 with which the valve 190 is associated,
the fuel can act upon the ball 202 so as to press it,
against resilient bias of the spring 206, inwardly
away from port 200 to permit fuel to flow from gallery
30 through the inlet port 200 into the portion 198a of
the cavity 198. From this portion 198a, the fuel can
flow into the cylinder 106 via the port 180 which port
communicates directly with cavity portion 198a.
The end of the body 189 opposite port 20Q has an
outlet port 210. During the aforedescribed admission
of fuel to the port 180 via the cavity portion 198a,
liquid flow from the cavity portion 198a via the port
210 is prevented by a second ball 212 which is
retained in a second portion 198b of cavity 198 and
which is resiliently biased, by a spring 214, against
a valve seat 220 formed in an apertured partition wall
198c between the cavity portions 198a, 198b whereby to
block flow through the partition wall. The spring
214 is ma~e sufficiently strong so as to prevent the
ball 212 being mov~d away from the seat 220 under
influence of pressure of fuel then in the chamber 198,
it being borne in mind that such pressure is
relatively reduced under the described condition of
radially inward movement of the piston during which
fuel is being admitted to the cylinder. On subsequent
radial outstroke of the piston 98, the fuel in the
cylinder space above the piston is forced back into
the cavity portion 198a through the port 180. Under
this condition, the ball 202 is acted upon by the fuel
pressure to firmly press it back against the port 200
to prevent fuel return back through gallery 30. On
the other hand, the fuel pressure in the cavity 198a
1260~7S~
18
then rises to a high level sufficient to overcome the
resilient bias of spring 214 thus forcing the ball 212
from the seat 220 to permit outflow of fuel from the
chamber 198 through the aperture in the partition wall
198c thence through the cavity portion 198b to the
outlet port 210,
The outlet ports 210 of the valves 190 are connacted
together at a branched end of the gallery 36 which
leads to the two fuel distributors 32 and 34.
.
The fuel distributor 34 includes a generally
cylindrical body 230 accommodated within housing 80
and having a central bore 232 therewithin. A
cylindrical spindle 234 is neatly accommodated within
bore 232 BO as to be free running therewithin. The
outer surface of spindle 234 sealingly engages the
surface o~ bore 232. Spindle 234 is attached to shaft
56 so as to be driven by the shaft during operation of
the pump 14O
Spindle 234 has an axial bore 234a therethrough and
three central shaft members 235, 236, and 237 are
retained therein at axially spaced positions. These
present therebetween two cavities 300, 302 within the
spindle~ Cavity 300 is bounded at opposite ends by an
end surface 235a of member 235 and an end surface 236a
of member 236. Cavity 302 is bounded by an axial end
surface 236b of member 236 and by an axial end surface
237a of member 237. Member 237 has however, extending
from surface 232a, an axial spigot 237b. The
peripheries of members 235, 236, 237 sealingly engage
the inner periphery of bore 234a. Members 235, 236
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19
may be axially immovable relative to spindle 234 but
element 237 is axially slidable for a purpose
described later. Cavities 300, 302 open to the
exterior of the spindle 234 via ports 238, 248 formed
in the ~ide wall of the spindle 234. Ports 238, 248
are displaced relative to each other by 180 around
the periphery of the spindle 234.
The body 230 is non-rotatably received in the main
housing 80 of the pump and has a number of ports in
the ~ide wall thereof. Most of these ports are not
visible in figure 2 but are shown in figures 5 to .16.
More particularly at the cross sectional location of
the cavity 300, body 230 has four equiangularly
disposed ports, 280, 282, 284 and 286 which extend
through the side wall thereof to provide ommunication
to the extexior surface of the spindle 234.
Similarly, at the cross-sectional location Qf the
cavity 302, there are four further ports through the
side wall of the housing 230, these being ports 288,
290, 292 and 294, again arrayed at equiangular
locations around the periphery of the body 230.
~ember 236 has a central axial bore therethrough and
thi~ has a pin 304 retained therein for neat sliding
and seali~g movement in the axial direction of the
~pindle 234. The bore within which pin 304 extends
open~ at oppo~ite ends to the cavities 300, 302, and
free ends 304a, 304b of the p~n 304 project into the
cavitie~ from ~urfaces 236a and 236b respectively. The
pin 304 is movable between two extreme positions
axially within the spindle 234. At one extreme, the
pin end 304a thereof engages the end surface 235a on
member 235, being the defining surface of cavity 300
opposite that from which pin end 304a extends into the
cavity. At the other extreme, the pin end 304b
engages the end of the spigot 237b on the surface 237a
of the member 237 opposite the surface 236b from which
the pin end 304b extends into cavity 302.
The ports 280, 284, 290 and 294 are each connected to
the gallery 36 from the high pressure pump 28. The
ports 282, 286, 288 and 292 are connected to
respective outlets from the pump 14, of which only one
outlet 336, being that associated with one of the
outlet ports 282, 286, is shown in Figure 2~ These
outlets are in use connected to the individual
injec~ors 52.
15 Figures 5 to 7 illustrate a condition of distributor
34 where cavity 300 is brought, at port 238 into fluid
flow alignment with inlet port 280 and at which the
cavity 302 is via port 248 in alignment with the
outlet port 292. It will first be assumed that,
20 immediately before reaching the condition illustrated
in figures 5 and 6, the pin 304 is first positioned so
that it extends fully into cavity 300 whereby the pin
end 304a engages the surface 235a. In this condition,
because of the co~munication provided from the ports
25 280 and 238 to the cavity 300, high pressure fuel from
the high pressure pump 28 can pass along the gallery
36 to the port 280 and thence into the cavity 300 J As
a result of this, there is a high fuel pressure in the
cavity 300. It is supposed, that, at this time, too,
30 there is a quantity of fusl within the cavity 302. A
consequence of the admission of high pressure fuel
~ Z 6C)7~
-lnto the cavity 300 is to cause that fuel to bear
against the transverse end face of the pin 304 at the
end 304a thereof whereby to move the pin from left to
right as viewed in f~gure 2 to the posit~on shown in
figure 7, under influence of that pressure. This
movement is terminated when the pin end 304b engages
the end surface 237a at spigot 237b. The movement of
the pin causes corresponding displacement of a volume
of fuel from the cavity 302 out through the port 292
which i~ at this time aligned with the port 248 from
cavity 302 and thence to the outlet associated with
poxt 292. On 90 of rotational movement of the
spindle 234, the ports 238, 248 of cavities 300, 302
are aligned relative to the various ports in the
member 230 as shown in figures 8 to 10. In this case,
fuel admitted through port 290 can pass into caYity
302 whereby the high pre~sure thereof causes the pin
304 to be moved lengthwise from the positio~ shown in
figure 7 so as to ca~se the pin end 304a to enter
cavity 300 whereby to displace fuel therein, being
fuel that had been retained in the cavity 300
following the inlet of fuel thereinto via the port 280
as mentioned. The displaced fuel passes out through
port 286. Figures 11 to 13 illustrate the condition
at a further 90 of rotation of the spindle, fuel here
being taken into cavity 300 from port 2~4 and being
displaced from cavity 302 by movement of the pin 304
into cavity 302, the fuel in cavity 302 leaving via
port 288. At the condition of flgures 14 to 16, at
which 270 of rotation has occurred, $he port 294 is
positioned for admission of fuel to cavity 302 whereby
to move pin 304 to eject fuel from cavity 300 via port
282.
' ~ :
~ Z~0758
22
The distributor 34 is provided with means for
permitting variation of the quantity of fuel delivered
from the outlet ports thereof. Thus, as mentioned,
member 237 is slidable within the interior bore of
shaft portion 236, and this movement varies the axial
width of the cavity 302 whereby to also vary the
maximum permissible stroke of the pin 304 by varying
the axial position of spigot 237a. A set screw 340 is
threadedly received in a threaded bore 342 in housing
10 80 coaxial with spindle 234 and this carries a ball
246 at its inner end which ball engagPs an outer end
of the member 237O Thus, by screwing set screw 340
inwardly, the member 237 can be moved axially to the
left as shown in figure 2 to reduce the permissible
15 allowed stroke of the pin 304, whilst withdrawal of
the set screw by unscrewing it causes the permissible
stroke to be increased. Although no specific
mechanism is provided to cause member 237 to move with
the set screw 340 when it is unscrewed, pressure in
20 the cavity 302 present in use serves to bias the
member 237 against the b~ll 246.
The distributor 32 is generally of like form to the
distributor 34 and, in figure 2, like components in
the distributor 32 are designated by like reference
numerals to those described in xelation to the
distribu~or 34. The following description of the
distributor 32, then, relates only to differences in
construction between the two di~tributors.
Firstly, in the distributor 32, the pin 304 is made of
rather larger diameter than the pin 304 in the
distributor 34 whereby to displace greater volumes of
. .: '
126~)758
fuel into the outlet ports, bearing in mind the need
for the distributor 32 to supply the aforementioned
injectors which supply t.he main combustion chamber
fuel requirements. Secondly, the set screw 340 is, in
5 the distributor 32, replaced by a slidable cylindrical
element 350 received in a bore 352 in housing 80.
Element 350 is axially aligned with the axis of
spindle 234 of distributor 32 and has retained at its
inner end a ball 354 which bears against the outer end
of member 237 of distributor 32.
A control membex 358 is positioned at the outer end of
element 35~ and is rotatable about an axis offset from
the axis of spindle 304 of distributor 32. This has
an outstanding radial arm 360 movable to turn member
15 358 about its axis. Member 358 is prevented from
axial movement in a direction away the outer end of
the element 350 by a thrust bearing 364 which engages
an end closure 366 threadedly received in threaded
bore 368 in housing 80. Member 358 has a ramped cam
20 surface 370 extending around the axis of member 358
and this is positioned to be adjacent the outermost
end of element 350. A ball 372 is interposed and
retained between the ramp surface 370 and the outer
end of the element 350. On turning of arm 360 to
25 rotate the member 358 about its axis, the point at
which the ball 372 engages the ramp surface 370 is
varied along the circumferential length o the cam
surface. Bearing in mind that, in use, the element
350 is axially biased by fluid pressure in the
3Q distributor 32 so as to cause the ball 372 to be
engaged with the surface 370, the described turning
motion of the member 358 causes variation in the axial
~6~'~S~
24
positioning of the element 350 to effect variation in
the positioning of the member 237 of distributor 32
whereby to effect variation of the stroke of the pin
304 and thus to vary the quantity of fuel delivered by
the distributor 32.
The spindle 234 of the distributor 32 is driven from
the shaft 90 via an advancing mechanism 382.
Mechanism 382 includes an annular piston 384 coaxially
mounted relative to shaft 90 and having inner and
outer peripheral side surfaces which slidingly and
sealingly engage inner and outer surfaces 388a, 388b
of an annular cavity 388 in housing 80, a~so coaxially
arranged relative to shaft 90. ~avity 388 is closed
at one end by an inner transverse suxfac~ of piston
384 and at the other end by an opposed transverse end
surface 388c of housing 80. Cavity 388 is connected
to gallery 26 by a drilling 390.
Mechanism 382 further includes two cooperating annular
cam members 392, 394. Member 392 is splined on shaft
90 so as to be driven by the shaft but axially
movable relative thereto. Member 394 is freely
rotatably carried on a bearing 396 on shat 90. The
spindle 234 of distributor 32 is coupled to member 394
so as to be rotatable therewith, the coupling being by
interengaging splines on these parts. Thrust bearings
398, 400 are interposed, on the one hand, between
piston 384 and me~ber 392 and, on the other hand,
between membar 39~ and an opposed transverse wall of
housing 80. A helical compression spring 404 is
interposed between members 392, 394 so as to normally
resiliently bias these away from each other to a limit
, ,-
iO7~8
position shown in figure 2 at which the piston 384
engages surface 388c of cavity 388, whilst the element
394 is biased against the bearing 400.
The members 392, 394 each have an equiangularly spaced
arxay of ramp projections 406, 408 respectively.
These have ramped cam surfaces 406a, 408a which
surfaces 406a, 408a engage with each other. Figure 3a
illustrates the members 392, 394 at the condition of
figure 2. By application of fluid pressure into
cavity 388 r piston 384 can be moved away from the end
surface 388c of cavity 388 thereby to move member 392
correspondingly against the resilient bias of spring
404~ During this movement, the cam surfaces 406a of
the projections 406 on member 392 slide over the
corresponding cam surfaces 408a of the projections 408
on member 394, as the distance between the two members
i 392, 394 is correspondingly reduced. Figure 3b shows
a condition at which the spacin~ has been so reduced,
and it will be noted therefrom that the effect of the
sliding over each other of the surfaces 406a, 408a is
to impart a component of relative rotational movement
to the member 394 as compared with the member 392.
The relative rotational positions assumed by the
members 392, 394 is thereby variable by varying the
fluid pressure within cavity 388 to vary the
positioning of the piston 384. Thus, during driving
of spindle 234 of distributor 32 from shaft 90 via
coupling 382, the relative rotational positions in
each rotational cycle at which outlet of liquid from
the distributor 32 occurs can be varied.
~0~
26
It is the case that the pressure in the gallery 26 is
primarily dependent on the speed of operation of the
pump 24 since, being a gear pump, the delivery rate
into the gallery 26 is proportional to driving speed.
Since shaft 56 is in use driven by the internal
combustion engine to which the pump is fitted for
supply of fuel, the pressure in the gallery 26 will
thus be dependent on the speed of rotation of the
engine. Likewise, then, the relative phase
displacement between the members 392, 394 and thus
; between the shaft 90 and the spindle 234 of
distributor 32 is proportional to the engine speed.
The direction of relative phase displacement between
the shaft 9Q and spindle 234 which occurs on increase
in speed is arranged such as to cause the angular
positions in each rotational cycle of the spindle 234
~t which outlet of fuel occurs to be relatively
advanced in each cycle as compared with that
prevailing at lower speeds. By this means it is
ensured that as engine speed increases fuel injection
into the injectors 54 is, as is required for normal
operation of fuel injected engines, made earlier in
each operating cycle of the engine.
While, as described, the primary influence on fuel
pressure in the gallery 26 is the speed of rotation of
the engine to which the pump 14 is attached, a
secondary influence on that pressure arises because
the pressure is also dependent upon the volu~e of fuel
taken per unit time from the gallery by the pump 28
The rate of removal of fuel from the gallery by the
pump 28 is in turn a function of engine load, because
greater volumes will be displaced from the distributor
q~
32 as engine load increases. Thus, although the pump
14 will in general operate to advance the angular
positions in each cycle of operation thereof at which
fuel is delivered, in accordance with engine speed,
there will also be some retarding effect where the
engine runs under heavy load. The angular fuel
delivery positions of the spindle 234 of distributor
32 will be advanced in accordance with engine speed of
the engine runs at constant load, but if the engine
runs at constant speed, the angular fuel delivery
positions will be retarded with increasing load. This
has been found to be particularly desirable, since a
slight retarding effect in fuel admission is desirable
under heavy load conditions~
While, as described, the set screw 340 is normally
pre-set to provide fixed predetermined quantities of
fuel to be delivered from the distributor 34, it is
possible to interconnect the set screw with housing 80
by a bimetallic spiral element operable to rotate the
set screw in accordance with temperature in a way
providing for increased fuel delivery quantities to
th~ auxiliary combustion chambers of the engine under
the condition of low temperature operation to give a
richer air-fuel mixture under those conditions.
25 The described distributors are arranged each to supply
four fuel injectors. Thus, the shaft 56 should be
arranged to be driven at one half of the engine
crank~~haft speed in order to derive the necessary
supply to each injector once in every full four-stroke
30 cycle, or a~ crank-shaft speed if applied to a
two-stroke engine.
1~60~7~
28
The described manner of varying the eccentric~ty of
the member 130 ensures that under initial starting
conditions, where there i~ little liquid pres6ure in
the cylinders 106, there i8 maximum eccentricity and
thus maximum stroke of the piston~. ~y this means,
during initial.cranking at start up, a relatively
greater volume of fuel is initially delivered from the
cylinders. On buildup of fluid pressure as a
condition of normal operation is approached, however,
fluid pressure in the cylinders is such as to cause
the eccentricity of the member io3 to be reduced to
its minimal condition by virtue of greater forces
being applied by the pistons through the cup shaped
elements 116 to the member 130 whereby to overcome the
spring bias provided by the springs 160, 162.
The described pump has been advanced in the context of
a pump suitable for operating a particular form of
internal.combustion engine of the kind described in
the aforementioned Canadia~ patent. ~owever,
it will be appreciated that the pump is readily
adaptable to supply fuel to fuel injectors of other
kinds of internal combustion engine. In particular,
engines not having the descrlbed subsidiary combustion
chamber~ may be supplied only from the distributor 32
in which casa the distributor 34 may be omitted.
The described arrangement has been advanced merely by
way of explanation and many modifîcations may be made
thereto without departing from the spirit and scope of
the invention as defined in the appended claims.
