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Патент USA US3068803

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, 3,068,793
Dec. 18, 1962 FUEL-INJECTION
2 Sheets-Sheet 1
Filed Aug. 28, 1958
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Filed Aug. 28, 1958
2 Sheets-Sheet 2
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Uit€ States
Patented Dec. 18, 1962
per stroke of the pump. This is achieved by combining the
pump with improved variable spill control means compris
ing a ?xed casing having a cylindrical bore containing a
John Neville Morris, Birmingham, England, assignor to
The S.U. Carbnretter Co. Ltd“, Erdington, Birmingham,
continuously rotating control shaft driven in variable phase
relationship to a driving shaft associated with the pump
plungers. A recess in the control shaft is arranged to effect
transient intercommunication of a pair of ducts in the
England, a British company
Filed Aug. 28, 1958, Ser. No. ‘757,731
Claims priority, application Great Britain §ept. 4, 1957
?xing casing. One duct receives metered fuel and the
4 Claims. (iii. 103-2)
This invention relates to fuel-injection pumps of the
reciprocatory plunger type for compression-ignition in
ternal combustion engines designed to meter liquid fuel
and to deliver it at relatively high pressures, that is to say,
at pressures in the region of 5,000 p.s.i. or upwards.
other duct leads to a spill outlet. A port in the bore of
the ?xed casing is connected to the supply of unmetered
fuel available in the auxiliary pumping chamber, which
port is situated approximately diametrically opposite, and
having a greater cross-sectional area than, that one of
the casing ducts which receives the metered fuel. In this
instance, the unmetered and pressurized fuel hydrostati
The invention is particularly applicable to fuel-injec
cally loads the control shaft to prevent leakage of the
early stage of the working stroke of the plungers, owing
to their differential pumping action, the unmetered fuel
becomes pressurized at the moment at which delivery of
the metered fuel commences, and simultaneously there
unmetered fuel available in the auxiliary pumping cham
ber. A supply duct in the distributor casing is provided in
permanent communication with the metered fuel outlet of
the pump and situated intermediate in said circumferential
grooves. A circumferential groove is provided in the
metered fuel from the vicinity of the aforesaid duets.
tion pumps which are also of the distributing type, in which
As already indicated, the invention is especially useful
either a single reciprocating plunger or a set of plungers
when employed in combination with means for distributing
meter and deliver fuel under high pressure to distributing
the high-pressure metered fuel output of the pump to a
means arranged to supply a multiplicity of engine 20 plurality
of engine cylinders in sequence. The distribut
ing means in question can be designed to take advantage
According to the invention a fuel-injection pump of the
of the supply of high-pressure unmetered fuel rendered
reciprocatory plunger type has a plunger which is asso
available in the auxiliary pumping chamber. Conse
ciated with a pumping chamber for delivering metered
quently, the invention can be used to great advantage as
quantities of fuel at high pressure. The metering plunger
follows. The fuel distributor is provided with a ?xed
is operable in conjunction with, and under the control
casing having a cylindrical bore containing a rotatable
exercised by, another plunger of larger effective cross
distributor shaft which is driven at some ?nite fraction
sectional area working in an auxiliary pumping chamber.
of the speed of the pump driving shaft. A pair of circum
The auxiliary chamber receives and is adapted to deliver
ferential grooves are provided in the bore of the distributor
unmetered fuel, the arrangement being such that at an
casing in permanent communication with the supply of
with means become effective to maintain the supply of
unmetered fuel, rendered available in the auxiliary pump
ing chamber, at a pressure which varies instantaneously
with, and remains approximately equal to, that of the
metered fuel.
In one embodiment of the invention, a fuel-injection 4:0
pump of the reciprocatory plunger type and arranged to
deliver metered fuel at high pressure is, in addition, de
signed to render available simultaneously a separate sup
ply of unmetered fuel at approximately the same pressure.
The pump includes a casing provided with a fuel inlet and
contains a pair of coaxial plungers of different diameter
contacting each other endwise by means of an abutment
provided upon an end face of one of the plungers. The
contact area of the abutment is substantially less than
the cross-sectional area of the other plunger. The ?rst
plunger has a spill duct which debouches at one end within
the area of the contacting surface of the abutment and
which at its other end is maintained in permanent com
munication with a region for receiving spillage of fuel.
The second plunger constitutes a movable boundary of
distributor shaft which groove is in register with the supply
duct and in permanent communication with a distributor
port in the distributor shaft. A plurality of radial outlet
ducts in the distributor casing are each connected to indi
vidual injection nozzles for respective engine cylinders
and cooperates individually with the distributor port. A
continuous groove in the distributor shaft surrounds the
distributor port and is in permanent communication with
the supply of unmetered fuel available in the auxiliary
pumping chamber. In this instance, the unmetered and
pressurized fuel develops regions of high pressure ‘sur
rounding the communicating conduits for the metered fuel
in the distributor means and thus prevents leakage of such
metered fuel at these vicinities.
The principal object of the invention is to enable a
fuel-injection pump of the type shown herein to provide
automatically a supply of unmetered and, therefore, is
in a limited sense, expendable fuel at a pressure approxi
mately equal to that of the metered fuel, wherein the
supply of expendable fuel remains available for a variety
a pumping chamber for metering fuel; whereas, the supply
of sealing purposes throughout the duration of the high
of unmetered fuel is rendered available in the pumping
pressure phase of the main metered fuel pumping action.
chamber of the ?rst plunger, which fuel becomes pressur
It is a further object and advantage of the invention
ized by the differential pumping action of the two plungers. 60 to provide a supply of unmetered and pressurized fuel
The last-mentioned chamber is referred to herein as the
in a fuel-injection pump concurrently with the delivery
auxiliary chamber. The pressure of the unmetered fuel
of metered fuel by the pump wherein, the supply of
is limited by the hydraulic Separation of the plungers and
unmetered fuel is expendable and available for sealing
the consequent uncovering of the spill duct. The pres
purposes in the pump. The unmetered fuel may be em
surized unmetered fuel may be ported or otherwise allowed
ployed to develop regions of high pressure in the pump
to develop regions of high pressure in the pump in order
proper or elsewhere in the fuel system such as in con
to prevent leakage of the metered fuel, that is to say,
trol means or distributor means, and thus may serve in
the unmetered and pressurized fuel may be employed in
lieu of commercially impractical and relatively expen—
numerous ways for hydraulically sealing the pump against
sive techniques of having close mechanical ?ttings be
undesirable leakage of the metered fuel.
tween contiguous or cooperating elements in the vicinity
The invention may advantageously be used in conjunc
of the fuel system where the metered fuel would other
tion with provision for varying the output of metered fuel
wise leak away; the unmetered fuel creates high pres
sure regions in such vicinities whereby leakage of metered
fuel is suppressed.
Further objects and advantages will become apparent
from the following description of the invention taken in
conjunction with the ?gures, in which:
FIG. 1A is a plan elevational view in section depict
ing a fuel-injection pump in accordance with the practice
region for receiving spillage of fuel, instead of leading
it into ?lling groove 15. An outwardly opening non
return valve 22 loaded by a spring 60 is situated at an
outlet 23 leading from metering pumping chamber 18.
The operation of the-pump is as follows. Commenc
ing at the outer or upper dead center position of plungers
8, 9, rotation of camshaft 12 permits the plungers to
move downwardly under the action of return spring 13,
as the plungersare maintained’ in mechanical contact by
of the invention; FIG. 1B is a fragmentary plan eleva
tional view in section and shows the practice of the inven 10 intervening abutment 14. During this phase, note FIG.
tion in control means used in conjunction with the pump
3, non-return valve 22 leading from the main or meter
of FIG. 1A for varying output of metered fuel; FIG. 1C
ing chamber 18 is closed, and thus a partial vacuum is
is a plan elevational view in section depicting the practice
of the invention in distributor means used in conjunc
tion with the pump of FIG. 1A;
FIG. 2 is a fragmentary and sectional view of the
pump shown in FIG. 1A and illustrates the upper por
tion thereof and in particular the relative positions of the
elements of the pump at the start of its downward stroke;
FIG. 3 depicts the apparatus shown in FIG. 2 wherein
‘the coacting elements are in their respective positions
just before the end of the downward stroke; and
formed, not only in chamber 18, but also in an auxiliary
Shortly before
the termination
constituted ofbythisannular
inward space
or down‘
ward stroke of plungers 8, 9, the upper end of larger
plunger 9 overruns ?lling groove 15 and, simultaneously,
ducts 16 and 17 in smaller plunger 8 establish commu
nication between pumping chamber 18 and auxiliary
pumping chamber 19. Thereupon, both pumping cham
bers 18 and 19 are enabled to inspire fuel by cavitation
from ?lling groove 15.
At an early stage of the ensuing outward or upward
stroke of plungers 8 and 9, the top end of plunger 9
FIG. 4 again shows the pump but in this instance the
“elements are in their respective positions depicting the
delivery or working stroke at an instant of time just after 25 travels above groove ‘15; consequently, both means, of
that represented by the positions of the same elements
communication leading from auxiliary pumping chamber
as illustrated in FIG 1A.
.19, that is to say, to ?lling groove 15 and to pumping
,The invention will now be described with reference
chamber 18, respectively, become cut off simultaneously
to the accompanying FIG. 1A. Liquid fuel is taken from
as shown in 1FIG. lA. The fuel previously inspired into
a supply tank 1 by a feed pump 2 and is delivered to an
metering chamber '18 now becomes pressurized to the
inlet 4 in the casing 5a of a fuel-injection pump 5. Pump
point where the non-return valve 22 opens against spring
_2 is provided with the usual relief valve 3. The main
‘60 and fuel delivery commences notwithstanding any, de
body of pump casing 5a is formed with a pair of coaxial
gree of back pressure which may be imposed, as, for in- '
, bores 6 and 7 in which are mounted plungers 8 and 9 re
'spectively. These plungers are of unequal diameter, and
one end of the larger plunger 9 protrudes from its bore
and is shaped, as at lower end 10, to co-operate with a
cam 11 mounted on a pump drive shaft 12.
A return
spring 13 reacts upon the upper end of smaller plunger
8. Spring 13 urges the two plungers into contact over
an area afforded by an abutment 14 on the plunger 9
and, additionally, maintains the protruding end 141 of
plunger 9 in contact with cam 11. Rotation of drive
shaft 12 and cam '11 against the action of spring'13 im
parts the upward stroke, sometimes referred to as out
ward motion, to plungers 8, 9; whereas, return spring 13
effects the downward stroke, sometimes referred to herein
as inward motion, to such plungers.
stance, by the type of nozzle commonly employed for
diesel engine injection, to which pump outlet 23 may lead.
It Will be assumed for the moment that an outlet 61
leading from chamber 19 is plugged up and thus fuel cap-.
tured in auxiliary chamber 19 momentarily will have no
means of egress.
Simultaneously with the aforesaid
action wherein fuel in chamber 18 becomes pressurized
to a point where valve 22 opens, the fuel contained in
. auxiliary chamber 19, rapidly rises to a pressure which
action upon the differential area existing between the
cross-sectional area of smaller plunger 8 and that of abut
ment 14 through which the two plungers make contact,
hydraulically separates the plungers and impels smaller
plunger 8 on its upward stroke. Smaller plunger 8 thus
tends to run away from larger plunger 9, but, in so doing,
it exposes spill duct 21 in larger plunger 9. The result is
taining larger plunger 9. Groove 15 as it is opera
50 that the fuel pressurized within annular chamber 19 is
tionally associated with fuel inlet 4 will be referred to
permitted to leak away via the suitably dimensioned duct
herein as the ?lling groove. Groove 15 is in such a posi
21 into circumferential groove 20 along the side of
tion that the upper end of plunger 9, remote from cam
plunger 9 and thence into ?lling ‘groove 15. Conse
11, overruns groove 15 shortly before the completion of
quently, a ?nite pressure is automatically sustained within
the inward or downward movement of plungers 8, 9. 55 auxiliary pumping chamber 19 throughout the remainder
Ducts 16 and 17 are provided in smaller plunger 8.
of the upward stroke of the plunger assembly; and this
Simultaneously with that overrunning action of larger
pressure is instantaneously somewhat but not much higher
plunger 9, ducts 1'6, 17 establish communication be
than the pressure obtaining in pumping chamber 18 in ac
tween metering pumping chamber 18, of which the upper
cordance with the elfective relative cross-sectional areas of
end of smaller plunger 8, remote from the cam 11, forms
smaller plunger 8 and of abutment 14. For example, if
the movable boundary, and the annular space 19 which 60 the cross-sectional area of smaller plunger '8 were 1 sq. cm.
results from the difference in diameter between the two
and the effective cross-sectional area of abutment 14 were
A circumferential groove 15 is formed in bore 7 con
plungers 8, 9.
‘In the particular example illustrated, a circumferen
tial groove 20 on larger plunger 9 is maintained in per
manent communication with ?lling groove 15, the widths
of these two grooves being so chosen as to ensure this.
Plunger 9 is provided with a spill duct 21 which de
approximately 0.1 sq. cm. then the pressure generated in
auxiliary chamber 19 during this phase would at any in
stant be approximately 10% greater than that obtaining
in pumping chamber 18.
One immediate consequence of this approximate equal
ity of pressures between annular chamber 19 and metering
chamber 18 is that the tendency for the metered fuel to
bouches at one end vwithin the face of abutment l4, and
which communicates at its other end with groove 20. 70 leak away from chamber 18 into what would, in the case
However, groove 20 is not an essential feature and it
of a conventional construction, be a region of approxi
could be dispensed with by simply increasing the radial ' mately atmospheric pressure, is greatly diminished and is,
depth of the ?lling groove 15. Moreover, the neighbor
ing end of ‘spill duct 21 could, if desired, be put into
in fact, at this much diminished rate, in the contrary direc~
tion. By this provision, it is clear that slight imperfec
permanent communication with any other convenient 75
tions in plunger-bore ?t, due to manufacturing errors or
to wear, can be tolerated without serious leakage of
metered fuel. A further attribute of the invention is
that the unmetered fuel contained in auxiliary chamber
19, that is to say, the fuel which has been referred as ex
pendable, can be conveyed by a duct 24 (assuming now
that outlet 61 is unplugged) leading from this chamber to
any point in the injection system at which it can perform
a sealing function or some other useful service.
established between the two grooves 38, 39 and source
19 of expendable high-pressure fuel. A further perma
nent communication is established between supply duct
40 and the metered fuel outlet 23 from the pump.
In the normal application of the distributing device, in
which a variable spill control 25, such as that already
shown in FIG. 1B, is required to be incorporated in the
fuel-injection system, two passages are provided from
the metered fuel outlet 23 from the pump; one, repre
Examples of useful applications for this expendable fuel
sented by connecting pipe 28, leading to such Variable
to other parts of a typical high-pressure fuel metering and 10 spill control 23 and the other, represented by a connect
distributing system, will now be described.
ing pipe 43, to the distributing device 35. A plurality of
Provision for enabling the output per stroke of the
equally spaced radial outlet ducts 44 debouch upon
pump to be varied, preferably by the abrupt spilling of the
bore 36 of the casing. Ducts 44- are in a plane longi
metered fuel at a variable point during the upward stroke
tudinally displaced from grooves 38, 3? and duct 40.
of metering injection plunger, is a normal requirement in
Each duct 44 is connected by a pipe 43 to a correspond
diesel engine operation. Such a variable spill control
ing injection nozzle 29. The number of nozzles 29 are
may conveniently be afforded by a device shown in FIG.
in accordance with the number of engine cylinders to
15 comprising a fixed casing 25 having a cylindrical bore
26 within which is mounted a continuously rotating con
trol shaft 27 driven by main pump shaft 12 through a
drive mechanism (not shown) arranged to permit the two
shafts to be phased or relatively rotated to a limited de
gee. This phasing or relative rotation of the shafts con
stitutes a means of varying the output of metered fuel per
stroke of the pump.
A connecting pipe 23, additional to that leading from
metered fuel outlet 23 of the pump to the injection nozzle
29, is arranged in parallel with the injection nozzle feed
be supplied.
The distributor shaft 37 has a circumferential groove
46 and a distributor port 47 spaced apart longitudinally
and interconnected by a duct 43. A continuous groove
49 such as can conveniently be formed by the operation
of trepanning surrounds the distributor port 47 in distrib
utor shaft 37. A duct 5%, which will be designated as
the pressurizing duct, debouches at one end upon the
surface of distributor shaft 37 and at its other end com_
municates with continuous groove 4&9. The arrangement
is such that, upon assembly, circumferential groove 46
pipe 3%}. Pipe 28 terminates in a duct 31 debouching
the distributor shaft registers with supply duct 40 in
upon bore 26 of ?xed casing 25. A further and adjacent 30 in
casing. Distributor port 47 in shaft 37 falls within
relief duct 32 leading to a region into which fuel may con
the plane containing the radial outlet ducts 44 of the
veniently be spilled, in this case supply tank 1 also de
casing; and pressurizing duct 5ft, where it debouches
bouches upon bore surface 26. Control shaft 27 is pro
upon the surface of shaft 37, registers with circumferen
vided with a recess 33 capable of effecting temporary
tial groove 39 in the bore of the fixed casing which com
communication between the two ducts 31, 32. In its 35 municates with source 19 of expendable high-pressure
simplest form, the device comprises only one such recess
33, and control shaft 27 is driven at the same speed as
The bores of the distributor port 47 and of the individ
pump drive shaft 12. The arrangement is such that rota
ual outlet ducts 44, at their intersection with the surface
tion of control shaft 27 effects spillage of the metered fuel
at any required interval after the commencement of the 40 of distributor shaft 37 and bore 36 of casing 35 respec
tively, are such that, whatever the timing of the pump
injection phase, in accordance with the variable relative
and spill control in respect of the duration of the injec
rotational positions of the two shafts concerned.
tion dwell, free communication is maintained between
A port 34 is provided within bore 26 of ?xed casing 25
distributor port 47 and one of the outlet ducts 44 through
and situated approximately diametrically opposite duct 31
out the duration of each injection dwell. A land 51 pro
which communicates with metered fuel outlet 23 from the
vided between the bore of the distributor port 4-7 and
pump. Port 34 has a cross-sectional area somewhat
the inner periphery of continuous groove 49 surrounding
greater than that of the duct 31. Port 34 is placed in
it, is, moreover, of sufficient width to ensure that groove
communication, by duct 24, with source 19 of the expend
able unmetered high-pressure fuel. The flow of expend
able fuel through port 34 is thus able to perform the use
ful function of hydrostatically forcing control shaft 27, to
the degree to which this shaft may be ?tted with some
small clearance in its bore, into intimate mechanical con
tact with the region of bore 26 at which the metered high
pressure fuel would otherwise tend to leak away by rea
son of local separation of the shaft from its bore. This
hydrostatic sealing action automatically commences at the
instant of pressure rise in the metered fuel and is auto
matically sustained throughout the high-pressure phase,
49 under no circumstances comes into communication
with any of the outlet ducts 44 during the injection phase
through that particular duct.
The metered fuel at the commencement of the injec
tion phase, passes by way of supply duct 40, into the
associated circumferential groove 46 of distributor shaft
D 37 and thence through the corresponding duct 48 in the
shaft to distributor port 47. The relative rotational po
sition of distributor shaft 37 with respect to main pump
shaft 12 is such that the fuel then enters one of the outlet
ducts 44 and passes to one of the injection nozzles 29
namely until recess 33 formed in the control shaft 27 60 associated with the engine cylinders. Supply to that par
tieular cylinder then continues until such time as the
causes spillage of the metered fuel.
injection phase is terminated, as by means of the spill
Another example of a useful application for the ex
device 25 previously described.
pendable high-pressure fuel is represented by a distrib
In the absence of a supply of expendable high-pressure
uting device, which is employed when the output from
fuel coinciding in time with the injection dwell, or in the
a single pumping unit has to be distributed to a plurality
absence of a commercially impracticable closeness of
of engine cylinders in sequence. This device as shown
?t between distributor shaft 37 and its bore 36, serious
in FIG. 1C comprises a ?xed casing 35 having a cylin
leakage of metered fuel would occur in the vicinity of
drical bore 36 which contains a rotatable distributor
supply duct 40 and its associated groove 46 in shaft 37,
shaft 37.
Shaft 37 is driven at some finite fraction of
the pump shaft speed, in accordance with the number 70 and also in the vicinity of distributor port 47. Such ex
pendable high-pressure fuel is, however, rendered avail
of engine cylinders to be served. The circumferential
able by the invention and is active from the moment of
grooves 38, 39 are provided in bore 36 of ?xed casing
commencement of the injection phase until the mo
35. Bore 36 also has a supply duct 40 spaced intermedi
ment of its termination. The presence of expendable
ately between grooves 38, 39. Communication, by way
of a connecting pipe 41 and passages 42, is permanently 75 fuel during this time, within the two circumferential
grooves 38, 39 in casing 35 and within the annular groove
49 surrounding the distributor port 47, serves, incidental
ly, to “reverse the direction of such leakage since the un
metered fuel is at somewhat higher pressure than the
metered fuel, and, in particular, serves to diminish con
siderably the extent of such leakage.
the confronting ends of said plungers being disposed in
the second chamber and normally held in contact by
the valve at the confronting end of the ?rst plunger seat
ing over the spill-duct outlet in the second plunger.
Since many changes could be made in the above con
struction and many apparently widely different embodi
ments of this invention could be made without depart
ing from the scope thereof, it is intended that all matter
contained in the above description or shown in the ac~
companying drawing shall be interpreted as illustrative
3. Apparatus as de?ned in claim 2, further including,
variable spill control means for varying the output of
metered fuel per working stroke of the pump, said spill
control means comprising a casing having a cylindrical
bore, a control shaft rotatable in said bore in variable
phase relationship in respect to said driving shaft, a pair
of ducts in said casing and debouching at the surface
of said bore, a ?uid passage extending from one of said
to the discharge port of said metering pumping
What is claimed is:
chamber, a ?uid passage extending from the other of
1. A fuel injection pump of the reciprocatory plunger 15 said ducts to the fuel spill ‘source, said control shaft
and not in a limiting sense.
type for delivering metered quantities of liquid fuel at
high pressure, comprising a housing having two com
municating co-axially disposed bores of different diamj
eters, the bore of smaller diameter having a substantially
closed end, a ?rst plunger reciprocable in said bore of
smaller diameter, a second plunger co-axial with the ?rst
plunger reciprocable in the bore of larger diameter, means
for reciprocating said plungers substantially in unison,
the ?rst plunger forming with said bore of smaller diam
eter and said closed end a metering chamber, said ?rst 25
plunger forming with said second plunger and said bore
of larger diameter a second chamber, means for adnut
ting and delivering liquid fuel into and from the metering
chamber, means for admitting sealing-liquid into said
second chamber, said second plunger having a spill-duct
one end of which has an outlet to said second chamber.
'and at its other 'end is in permanent communication
having a spill recess arranged to effect, during rotation,
transient intercommunication between said pair of ducts,
a port in said casing, communicating with said spill casingv
bore surface approximately diametrically opposite and
having a cross-sectional area greater than the aforesaid
duct communicating With said discharge port in the meter
ing pumping chamber and a ?uid passage extending from
said last port to said second chamber in the pump
4. Apparatus as de?ned in claim 2 further including,
' distributor means for distributing metered fuel from said
metering pumping chamber to a plurality of engine cyl
inders in ‘desired sequence, said means for reciprocating '
said plungers including a driving shaft, said distributor
means comprising, a casing having a cylindrical bore, a
distributor shaft rotatable in said bore at some ?nite frac
tion- of pump driving shaft speed, a pair of spaced cir
with a region for receiving spillage of sealing-liquid
cumferential grooves in the bore surface of said distribu
from ‘the second chamber, the confronting ends of said
tor casing, a ?uid passage extending from said grooves to
plungers having different effective cross-sectional areas 35 a discharge port in said second chamber in the pump
responsive to liquid under pressure in the second cham
housing for receiving fuel therefrom, said distributor shaft
ber and means on the confronting end of said ?rst
a circumferential groove disposed between said
plunger constituting a valve for closing said spill-duct
pair of circumferential grooves, a ?uid passage for main
outlet during the non-working stroke of the plungers,
taining the distributor shaft circumferential groove in’
movement of the second plunger during its working
communication with the discharge port of said meter
stroke operating to (1) pressurize sealing-liquid ad
chamber, said distributor shaft also having
mitted to the second chamber, (2) pressurize fuel ad
a duct therein in ?uid communication with said last
mitted to the metering chamber, (3) cause the ?rst plunger
mentioned circumferential groove, said distributor casing
to move to discharge the metered fuel, (4) diminish
a plurality of spaced radial outlet ducts therein
the tendency of the pressurized fuel to leak away from
for connection with respective ducts leading to the engine
said metering chamber, and (5) cause the ?rst plunger
cylinders, said duct in the distributor shaft registering,
to move axially more rapidly than the second plunger
individual ones of said radial outlet ducts upon ro
to hydraulically open the valve and permit part of said
tation of said distributor shaft, and said annular groove
pressurized sealing-liquid to discharge through the spill
in the peripheral surface of said distributor shaft sur
duct and thereby effectively to vary the pressure on the
said duct in the distributor shaft, said last
sealing-liquid in the second chamber instantaneously with,
groove being in permanent ?uid communica
and maintain said pressure approximately equal to, the
tion with said pair of circumferential grooves forreceiv
pressure on the metered fuel.
ing fuel from said second chamber.
2. A fuel injection pump according to claim 1, Where
in the sealing-liquid is the liquid fuel, the casing and the r
References Cited in the ?le of this patent
?rst plunger having ports controlled by the movement
of the plungers for charging fuel from a source into
said chambers during the intake stroke of the plungers
Bradbury _____._____y__~_.__>_ Dec. 1, 1925
and for cutting off said chambers from said source at
an early stage of the working or discharge stroke, said
metering chamber having a port controlled by a valve
Austria _____________ __'_,May 15, 1956
for discharge of fuel from the metering chamber and
Great Britain _________ __ Nov. 28, 1951
France _______________ _- Feb. 3, 1947
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