Fuel injection pumping apparatus

A fuel injection pumping apparatus for supplying fuel to a compression ignition engine has an annular cam ring which has internal cam lobes for imparting inward movement through cam followers respectively to pumping plungers mounted in a rotary distributor member. Stop rings are mounted alongside the cam ring to determine the maximum outward movement of the plungers. The stop rings are angularly adjustable to enable the maximum amount of fuel supplied to the engine to be varied. Two adjusting devices are provided the first being a piston which is subject to a fluid pressure varying with speed. The piston is biased by a spring and sets the stop rings to allow an excess of fuel for engine starting purposes and the second is a diaphragm assembly responsive to the air pressure in the engine inlet manifold. In order to save space the piston is slidable within a housing which also accommodates the diaphragm assembly and the diaphragm assembly is coupled to the stop rings by means of a push rod which passes through an aperture in the piston.

This invention relates to a fuel injection pumping apparatus for supplying 
fuel to an internal combustion engine, the apparatus being of the kind 
comprising a rotary distributor member housed in a body, a transverse bore 
in the distributor member and a reciprocable plunger therein, a cam 
follower at the outer end of the plunger, an annular cam ring surrounding 
the distributor member and having inwardly directed cam lobes on its 
internal surface for engagement by the cam follower to impart inward 
movement to the plunger as the distributor member is rotated in 
synchronism with the associated engine, means for feeding fuel to the bore 
during at least part of the time the plunger is allowed to move outwardly 
by the cam lobes, passage means in the distributor member and body through 
which fuel displaced by said plunger during successive inward movements 
thereof is supplied to outlets in turn, a stop ring or rings mounted in 
the body, the stop ring or rings being engageable by the cam follower to 
limit the extent of outward movement of the plunger, the internal surface 
or surfaces of the stop ring or rings being shaped so that angular 
adjustment of the ring or rings will effect variation in the extent of 
outward movement of the plunger and thereby the maximum amount of fuel 
which can be supplied to the associated engine. 
The ring or rings must be adjusted in use to allow an excess of fuel to be 
supplied to the associated engine for starting purposes and also in the 
case of a supercharged or turbo charged engine in accordance with the 
pressure of air in the inlet manifold of the engine. It is convenient to 
dispose the mechanisms which determine the excess fuel and the variation 
with air pressure in tangential relationship to the ring or rings since 
this simplifies the linkage connecting the mechanisms to the ring or 
rings. If separate mechanisms are used there occurs the problem of 
mounting the mechanisms on the body of the apparatus bearing in mind that 
the apparatus is secured to the structure of the associated engine in such 
a manner that one side of the apparatus lies in close proximity to the 
cylinder head or cylinder block of the engine. Any attempt to space the 
apparatus further from the engine will require redesign of the mounting 
for the apparatus and also the drive connection with the engine 
crankshaft. A further problem arises with the design of the apparatus 
since this already has a pressure operable timing piston which is located 
in tangential relationship to the cam ring. 
The object of the invention is to provide such an apparatus in a simple and 
convenient form. 
According to the invention an apparatus of the kind specified comprises a 
housing for attachment to the body, a piston slidable within a bore in the 
housing, the bore opening at one end to the interior of the body so that 
the piston is acted upon by fuel pressure within said body, valve means 
for ensuring that the fuel pressure increases within said body after 
starting of the associated engine, an abutment engageable by the end of 
the piston exposed to the pressure in the body, linkage means connecting 
said abutment with said stop plate or plates, first resilient means 
biasing said piston against the action of the fuel pressure and acting to 
urge the stop plate or plates in a direction to increase the amount of 
fuel which can be supplied to the associated engine, a rod slidable within 
a central aperture in the piston, one end of the rod being engageable with 
said abutment means, a diaphragm assembly mounted in the housing and 
including a spring loaded diaphragm upon which in use air under pressure 
in the air inlet manifold of the engine can act, the assembly including a 
member engageable with said rod to move the rod independently of the 
piston to adjust the setting of said stop plates. 
By the arrangement outlined above the mechanisms for setting the stop plate 
or stop plates for the purpose of obtaining an excess of fuel for engine 
starting purposes and for adjusting the stop plate or plates in accordance 
with the air inlet manifold pressure are combined in a single housing 
which can be located on the body of the apparatus at any suitable position 
.

Referring to FIG. 1 of the drawings the apparatus comprises a body 10 in 
which is located a sleeve which carries a rotary cylindrical distributor 
member 11. The distributor member is coupled to an input shaft 13 which 
extends from the body and which is adapted to be driven in timed 
relationship with an engine with which the apparatus is associated. Formed 
within an enlarged portion 12 of the distributor member is a transverse 
bore 14 in which is mounted a pair of reciprocable plungers 15 which are 
arranged to be moved inwardly as the distributor member rotates, through 
the intermediary of cam followers, by cam lobes formed on the internal 
peripheral surface of an annular cam ring 18 which is mounted for angular 
adjustment within the body. Each cam follower includes a shoe 16 and a 
roller 17 and the followers are located in slots respectively formed in a 
part 19 driven by the input shaft. 
Also formed in the distributor member 11 is a longitudinally extending 
passage 21 which at one end is in communication with the bore 14 and at 
its other end is in communication with a radially disposed delivery 
passage 22. The delivery passage is arranged to register in turn with a 
plurality of equiangularly spaced outlet ports 23 which are in use 
connected by pipelines respectively to injection nozzles mounted on the 
associated engine. The aforesaid registration of the passage 22 with one 
of the outlet ports takes place during the whole time the plungers 15 are 
being moved inwardly so that liquid fuel contained in the bore 14 will be 
displaced to a combustion space of the engine. 
At another point the longitudinal passage 21 is in communication with a 
plurality of equiangularly spaced and radially disposed inlet passages 24. 
The passages 24 are arranged to register in turn with an inlet port 25 
which is formed in the body. In practice, in order to facilitate filling 
of the bore 14, two inlet ports 25 are provided these being angularly 
spaced by an amount equal to the angular spacing of the inlet passages 24. 
The inlet ports 25 communicate with a throttle device 26 the setting of 
which is controlled by a speed responsive governor and the device 
communicates with the outlet 27 of a low pressure supply pump 27A having 
an inlet 28, the supply pump being located in the body 10. The supply pump 
incorporates a relief valve 27B so that its output pressure will vary in 
accordance with the speed at which the distributor member is driven. The 
arrangement is such that when the inlet passages 24 register with the 
inlet ports, fuel will flow from the outlet of the low pressure pump to 
the transverse bore 14 to effect outward movement of the plungers. The 
aforesaid registration takes place only during the time when the delivery 
passage 22 is out of register with an outlet port 23 and during the time 
when the rollers 17 are clear of the cam lobes. By adjusting the setting 
of the throttle device 26, the rate at which fuel can flow to the bore 14 
can be controlled and hence also the amount of fuel delivered to the 
associated engine. 
In order to control the maximum amount of fuel which can be supplied to the 
associated engine, a pair of stop plates 29 are positioned on the opposite 
sides of the cam ring 18. The stop plates 29 are interconnected by a 
bridge member 30 on which is mounted an actuating peg 31. The peg 31 is 
connected to adjusting mechanism as will be described with reference to 
FIG. 2, and the stop plates 29 define shaped stop surfaces having a radial 
dimension which increases in the direction of rotation of the distributor 
member. The stop surfaces act to limit the extent of outward movement of 
the plungers which can take place whilst the inlet passages 24 are in 
communication with the inlet ports 25. By varying the angular setting of 
the stop plates therefore the extent of outward movement of the plungers 
can be controlled. 
A space within the body is supplied with fuel under pressure from the 
outlet 27 of the low pressure pump by way of a restrictor 32. The pressure 
of fuel within the space is controlled by a relief valve 33 which 
maintains a predetermined maximum pressure within the space by venting the 
fuel to a drain which may be the inlet of the low pressure pump. The flow 
of fuel into the space provides for lubrication of the working surfaces of 
the various parts within the space and it also assists in the removal of 
air which may be contained in the fuel. 
Referring now to FIG. 2 of the drawings the apparatus includes a housing 34 
which is secured to the body 10 to one side of the axis of rotation of the 
distributor member which is indicated in FIG. 2 at 35. The housing 34 
defines a stepped internal surface the narrower portion of which 
constitutes a bore 36 which communicates with the space in the body. 
Slidable within the bore 36 is a piston 37 and this is biased in a 
direction into the space within the body, by means of a coiled compression 
spring 38. The opposite end of the compression spring is engaged with an 
abutment plate 39 which is secured against a step defiined by the internal 
surface of the housing. 
The piston 37 is engageable with an abutment 40 and this is coupled by 
means of a linkage generally indicated at 41, with the peg 31. The linkage 
is lightly biased by a spring 40A so that the abutment 40 is urged into 
contact with the piston 37. 
The end of the housing remote from the body 10 is closed by a closure 
member 42 and sandwiched between the closure member 42 and the housing 34 
is the outer periphery of a diaphragm 43 which forms part of a diaphragm 
assembly. Included in the diaphragm assembly is a mushroom-shaped member 
44 defining an externally screw threaded shank 45 which is also provided 
with an internal thread which is engaged by a push member 46. The inner 
peripheral surface of the diaphram is held against the underside of the 
head of the member 44 by means of an annular plate member 47 which is in 
screw thread engagement with the shank and which is locked in position by 
means of a locking nut 48. 
The intermediate portion of the interior surface of the housing is provided 
with a screw thread which serves to mount an annular stop member 49 and 
slidable within this member is the skirt portion of an annular member 50 
which defines an inwardly extending flange which is urged into engagement 
with the head of the mushroom-shaped member 44 by means of a coiled 
compression spring 51, the spring 51 at its end remote from the flange 
engaging with the abutment plate 39. Also forming part of the diaphragm 
assembly is a guide member 52 which is slidable through a central aperture 
in the abutment plate 39 and which defines a central bore 53 in which is 
slidably mounted a push rod 54. The push rod extends through a central 
aperture 55 in the piston 37 so that it can engage with the abutment 40. 
The space between the diaphragm 43 and the piston is vented to a drain 
such as the inlet of the pump 27A and the space defined between the 
closure member 42 and the diaphragm is connected to the inlet manifold of 
the associated engine which is of the turbocharged variety. An additional 
spring 56 is mounted between the diaphragm assembly and an adjustable 
closure 57, which is adjustably mounted on the closure member 42. The 
spring 56 acts in opposition to the spring 51 but is of lesser strength 
and is provided for the purpose of adjusting the effective spring force 
acting on the diaphragm assembly. 
In operation, and assuming for the moment that the connection to the inlet 
manifold is disconnected. With the engine at rest the piston 37 is urged 
by its spring 38 to the position shown in FIG. 2 and in so doing it urges 
the abutment 40, the linkage 41 and the peg 31 to a position in which the 
stop rings permit an excess amount of fuel to be supplied to the 
associated engine for starting purposes. 
When the associated engine has started the fuel pressure within the space 
in the body 10 starts to increase and when the pressure on the piston 
balances the force exerted by the spring 38, the piston will move towards 
the left as seen in FIG. 2 and by virtue of the light spring 40A which 
loads the linkage, the stop plates will move to reduce the maximum amount 
of fuel which can be supplied to the engine. The normal maximum amount of 
fuel is determined when the push rod 54 engages the push member 46. Since 
the push member 46 is adjustably mounted in the mushroom-shaped member 44, 
the maximum amount of fuel can be preset, this maximum corresponding to 
low load operation of the engine when the turbocharger is ineffective. 
Assuming now that the connection to the inlet manifold is in place and the 
load on the engine is increased. As the turbocharger begins to pressurize 
the air in the air inlet manifold, the diaphragm assembly will start to 
move towards the right as seen in FIG. 2 against the action of the spring 
51 and the rod 54 will be urged by the push member 46 towards the right 
thereby moving the abutment 40 in the direction to increase the maximum 
amount of fuel which can be supplied to the associated engine. The extent 
of movement of the diaphragm assembly and hence the extent by which the 
maximum amount of fuel can be increased, is determined by the abutment of 
an annular projection 59 on the external surface of the skirt portion of 
the push member 50, with the annular stop member 49. 
It is convenient to temporarily prevent movement of the diaphragm assembly 
whilst the pressure in the inlet manifold builds up and this is achieved 
by shielding the diaphragm 43 from the actual air inlet manifold pressure 
using the annular plate member 47 which as will be seen in FIG. 2, mounts 
a seal member 58 which is engageable with a step defined on the closure 
member 42. The effective area of the member 47 is less than that of the 
diaphragm so that a differential action is obtained. 
It will be noted that the housing 34 together with the closure member 42 
which accommodate the piston and the diaphragm assembly are located on one 
side of the main body 10 and this facilitates the mounting of the pumping 
apparatus on the associated engine.