Fuel injection pump for internal combustion engines

A fuel injection pump of a distributor injection pump type in which a quantity adjusting device is an annular slide that is axially displaceable on a fuel injection quantity regulator and which can additionally be rotated by a torque device. With the aid of this torque device, the control effectiveness of a second control edge, for instance in the form of a rectangular groove is controlled. The torque device is equipped with a clutch, which is embodied either via a spring or via a cam race. The torque device is actuated via an adjusting lever connected to the annular slide adjusting lever that serves to arbitrarily vary the fuel injection quantity at the direction of the driver of the motor vehicle.

BACKGROUND OF THE INVENTION 
The invention is based on a fuel injection pump for internal combustion 
engines. In a fuel injection pump known from German Offenlegungsschrift 
No. 32 13 724, the pump piston has as its relief conduit an axial blind 
bore originating at the pump work chamber, from which bore a transverse 
conduit branches off to two first outlet openings. A radial conduit also 
branches off to a second outlet opening. This second outlet opening is 
offset with respect to the first outlet openings toward the pump drive 
side and cooperates with a radial bore, which is disposed in the annular 
slide and by way of which, serving as a conduit, a communication with the 
relief chamber can be established. In the known fuel injection pump the 
radial bore is disposed such that, at an annular slide position 
corresponding to the low-load operating range during the pump piston 
supply stroke, the second outlet opening is in communication with the 
radial bore, while in the full-load range, the second outlet opening does 
not come to communicate with the radial bore. This apparatus serves to 
allow only some of the supply strokes of the pump piston to be effective 
in the low-load range; accordingly, a plurality of radial bores are 
provided, distributed around the annular slide, so that only every other 
pump piston supply stroke, for instance, leads to a pressure buildup in 
the pump work chamber and hence to the injection of fuel. Correspondingly, 
only half of the cylinders of the internal combustion engine serve to 
drive the engine. This provision is meant to lower fuel consumption in the 
partial-load range. 
A fuel injection pump of this type is also known from German 
Offenlegungsschrift No. 32 18 275, in which instead of the radial bores in 
the annular slide provided in the above-described known fuel injection 
pump, diametrically extending grooves originating at the end face of the 
annular slide are provided, which now, and together with the face end of 
the annular slide serving as a first control edge, cooperate with only a 
single outlet opening of the relief conduit. Thus the grooves have the 
second control edges for controlling the communication between the pump 
work chamber and the relief chamber prior to the coming into play of the 
first control edge. The annular slide here is not only axially 
displaceable on the pump piston as a function of the adjustment of a fuel 
injection quantity regulator, but is also rotatable by a torque device. By 
means of rotation, during the supply stroke of the pump piston, the outlet 
opening can be made to come into communication with one of the 
diametrically extending grooves in alternation, upon every supply stroke, 
or every other supply stroke, of the pump piston, depending on the number 
of grooves provided. Thus either the number of injections can be reduced 
by half, for example, similarly to what is known from the prior art 
described initially above, or the high-pressure supply of the fuel 
injection pump can be suppressed entirely. Furthermore, by reducing the 
width of the grooves, it is possible merely to throttle the outflow of 
fuel during a particular supply stroke, in order to reduce the fuel 
injection rate in the lower rpm range. 
The quite-idle device that is thus realized has the effect that the engine 
can be operated while idling, for instance, with less combustion noise. 
For rotating the annular side, the known torque device is coupled rigidly 
to a crank, which is rotated during engine idling to cut off individual 
cylinders. 
OBJECT AND SUMMARY OF THE INVENTION 
The fuel injection pump according to the invention has the advantage over 
the prior art that the rotation of the annular slide for making the second 
control edge effective is effected automatically upon the arbitrary 
selection by the driver of the motor vehicle. In accordance with the 
desired torque or engine rpm at a given load, the adjusting lever of the 
fuel injection pump that supplies the engine with fuel is rotated. The 
torque device is advantageously coupled to this adjusting lever in such a 
way that the annular slide can be rotated only in a predetermined rpm 
range without restricting the rotatability of the adjusting lever. 
In an advantageous feature of the invention, the pivoting device is coupled 
to the adjusting lever of the fuel injection pump via a torsion spring. By 
means of a stop range within which the shaft that moves the pivoting 
device can be rotated, the adjusting range can be adjusted in alternation 
and can also be easily changed afterward. 
In another embodiment of the invention, the torque device is very simple, 
with few moving parts. In a further development of this feature, exact, 
smooth guidance, that is, without sticking, of the adjusting bolt that 
embodies the pivoting device is attained. In another advantageous feature 
of the invention, parts imperiled by wear, such as the restoring spring of 
the adjusting bolt, are disposed outside the fuel injection pump, where if 
they fail they do not threaten fuel injection pump operation to such an 
extent that fuel regulation failure could damage the engine. 
The invention will be better understood and further objects and advantages 
thereof will become more apparent from the ensuing detailed description of 
preferred embodiments taken in conjunction with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A bushing 2 is disposed in a housing 1 of a fuel injection pump shown in 
cross section in FIG. 1. An inner bore 3 of bushing 2 forms a pump 
cylinder within which a pump piston 4 driven by a cam drive 5 executes a 
simultaneously reciprocating and rotating motion. On one face end, the 
pump piston encloses a pump work chamber 6 and the other end protrudes 
partway out of the inner bore 3 into a pump suction chamber 7, which is 
enclosed in the housing 1. 
The pump work chamber 6 is supplied with fuel, via longitudinal grooves 8 
disposed in the jacket face of the pump piston and via a suction bore 9 in 
the housing that originates at the pump suction chamber 7, the fuel passes 
radially through the bushing 2 and the suction bore within the housing 1 
as long as the pump piston is executing its intake stroke or assumes its 
bottom dead center position. The pump suction chamber is supplied with 
fuel from a fuel tank, not shown here, via a feed pump 11. By means of a 
pressure control valve, not shown, the pressure is typically controlled in 
accordance with rpm in the suction chamber, so as to enable making an 
rpm-dependent injection adjustment, for example hydraulically, via a 
pressure control as a function of rpm. With increasing rpm, the stroke 
onset of the pump piston is adjusted to "early" in a known manner. 
In the pump piston, a longitudinal conduit 14, which is embodied as a blind 
bore leads away from the pump work chamber 6 and serves as a relief 
conduit. Branching off from the relief conduit is a transverse bore 15, 
which leads to first outlet openings 16 on the circumference of the pump 
piston 4, into a region in which the pump piston protrudes into the 
suction chamber 7, which at the same time serves as a relief chamber for 
fuel that is put under high pressure in the pump work chamber 6. The 
outlet openings 16 are preferably located diametrically opposite one 
another, which results in a balanced hydraulic load on the pump piston. 
Disposed on the pump piston in this region is a quantity adjusting device 
in the form of an annular slide 18, which with the jacket face of its 
inner ring slides tightly on the pump piston. This annular slide is 
rotatably adjustable and axially displaceable, and with a first control 
edge 19, embodied by the jacket face and an upper face end, the annular 
slide controls the first outlet openings 16. 
Also branching off from the relief conduit 14, which preferably extends 
coaxially with the pump piston axis, is a radial bore 20, which leads to a 
distributor opening 21 on the circumference of the pump piston. In the 
operating region of this distributor opening, a plurality of feed lines 22 
branch off from the inner bore 3 in a radial plane, which are distributed 
on the circumference of the inner bore 3 in accordance with the number of 
cylinders of the associated engine that are to be supplied with fuel. The 
fuel feed lines lead via one valve 23 each, which is embodied in a known 
manner as a check valve or pressure relief valve, to the fuel injection 
locations, not shown. As soon as the suction bore 9 is closed by the 
jacket face of the pump piston, at the onset of the supply stroke of the 
pump piston following a corresponding rotation of the pump piston, the 
fuel located in the pump work chamber 6 is pumped to these injection 
locations via the relief conduit 14, the radial bore 20 and the 
distributor groove 21. This pumping is interrupted whenever the first 
outlet openings 16, in the course of the pump piston stroke, are opened by 
the control edge 19 and come into communication with the suction chamber 
7. From that point on, the remaining fuel positively displaced by the pump 
piston is pumped only into the suction chamber. The higher the level at 
which the annular slide 18 is adjusted toward the pump work chamber, the 
greater the quantity of fuel pumped by the pump piston. 
The fuel injection quantity regulator 25 provided for the adjustment of the 
annular slide has a tensioning lever 26, which is pivotable about a shaft 
27, and is coupled at its lever arm end to a governor spring assembly 28. 
This assembly comprises an idling spring 29 disposed between the head of a 
coupling element 30 and the tensioning lever; the coupling element 30 is 
passed through an opening in the tensioning lever, and at its other end, 
remote from the head, it is connected to a main governor spring 31. The 
main governor spring 31, in turn, is suspended at one end from a pivot arm 
33, which is adjustable with an adjusting lever 35, via a shaft 34 passed 
through the pump housing. The adjusting lever is arbitrarily actuatable 
between an adjustable full-load stop 36 and an adjustable idling stop 37 
by a person operating it. For instance, the adjusting lever 35 is 
connected to the gas pedal, which the driver of the motor vehicle equipped 
with the engine and fuel injection pump actuates in accordance with the 
torque he selects. Instead of the simple helical spring shown here as the 
main governor spring, it is naturally also possible to use other governor 
spring assemblies that are of the multi-stage and/or pre-stressed type. 
A starting or governor lever 39 is also pivotable about the shaft 27; it is 
two-armed, with one arm, including a ball head 40 which engages a 
transverse groove 41 in the annular slide extending in a radial plane to 
the annular slide by which it is coupled to the annular slide. The other 
arm of the starting lever has a leaf spring 49, which is braced against 
the tensioning lever 26 and serves as the starting spring thereby forcing 
the arm from the tensioning lever 26. Acting upon this particular lever 
arm of the starting lever 39 is the final control element 42 of an rpm 
transducer in the form of a flyweight control assembly 43 of a known type, 
which is driven synchronously with the drive shaft 44 of the fuel 
injection pump, via a gear train 45. With increasing rpm, the final 
control element 42, along with the starting lever 39 and the annular slide 
18, is accordingly displaced counter to the force of the starting spring 
49, until the starting spring comes to rest on the tensioning lever 26. In 
the course of this movement, the annular slide is adjusted away from a 
highest position, nearest the pump work chamber and corresponding to a 
starting quantity setting, toward the pump piston drive side, thus 
reducing the increased starting quantity. Once the starting lever comes to 
rest on the tensioning lever, both levers become pivotable counter to the 
force of the idling spring 29, until the main governor spring 31 comes 
into action, adjacent the idling range. Depending upon the embodiment of 
the main governor spring as either a variable- speed governor spring or a 
miminim-maximum-speed governor spring, the tensioning lever is moved 
onward upon reaching the set rpm, and the annular slide 18 is displaced in 
order to reduce the injection quantity. In other words, a greater or 
lesser quantity of fuel is injected at a given rpm, depending on the 
position of the adjusting lever 35. 
For adjustment, the shaft 27 is supported on an adjusting lever 46, which 
is pivotable about a shaft 47 attached to the housing and is kept in 
contact with an adjustable stop 48 by a spring acting upon one end. 
To the extent described thus far, the fuel injection pump is equivalent to 
a standard, known version. In addition, a rectangular groove 51 is now 
provided on the face end of the annular slide 18 oriented toward the pump 
work chamber 6; similarly to the subject of German Offenlegungsschrift No. 
32 18 275 discussed initially above, this groove 51 may be embodied either 
as a throttling groove having a throttling cross section, or as a cutoff 
groove having a correspondingly larger cross section. One of the limiting 
edges of the rectangular groove makes a second control edge available, 
which cooperates with the outlet openings 16 and opens them earlier than 
does the first control edge 19. By rotating the annular slide 18, this 
groove 51 can now be put into its operating position, so that it comes 
into communication with the outlet opening 16 during the supply stroke of 
the pump, or into the turned-off position, such that it is inoperative for 
control purposes and the outlet opening 16 is opened toward the relief 
chamber 7 only by the control edge 19. To this end, a torque device 52 is 
provided, which has a pivoting device 53 in the form of a bell crank, on 
one lever arm 54 a ball head 55 is integrally formed; as a sliding 
element. The ball head engages a longitudinal groove 47 on the slide 18 by 
which radial adjustment is accomplished. The lateral limiting faces of the 
longitudinal groove, which extends axially parallel, represent guide faces 
for the ball head 55 and permit an axial adjustment of the annular slide 
18 by the fuel injection quantity regulator 25, without rotation of the 
annular slide at the same time. Naturally a technological equivalent can 
be provided in the form of a claw on the lever arm 54 and a guide nose or 
guide gudgeon on the annular slide. Depending on the embodiment, the guide 
faces are then located on the guide nose or guide rib, or on the claw. 
The bell crank 53 is supported on a shaft 58, which is connected to the 
housing and has as its other lever arm a U-shaped strap 59, which is 
additionally supported on its end on the shaft 58, as shown in FIG. 2. An 
actuating arm 62 that is mounted eccentrically on the face end 63 of a 
shaft 64 engages a recess 60 of the U-shaped strap 59. The shaft 64 is 
guided in an inner bore 65 of a bushing 66, which is inserted tightly from 
the outside into the housing 1 of the fuel injection pump. On its end that 
protrudes outward, the shaft 64 has a diameter reduction 67, on which a 
hub 68 of an adjusting lever 69 is supported. The adjusting lever is 
secured in the axial direction toward the outside by a form-fitting lever 
70, which is retained by a nut 71 that is screwed onto the end of the 
shaft 64. One end of a pre-stressed torsion spring 73 is suspended from 
this lever, which is accordingly fixed to the shaft 64 so that the lever 
and shaft do not rotate relative to one another; the other end of the 
torsion spring 73 is suspended from the adjusting lever 69. Because of its 
initial stress, the torsion spring keeps the adjusting lever 69 in contact 
with the arm 72 of the lever 70 and thus effects coupling of the adjusting 
lever 69 to the shaft 64. A disk 74, the form of which is more clearly 
shown in the plan view of FIG. 3, is mounted between the diameter 
reduction 67 and the shaft. This disk 74 has two arms 76, which engage a 
recess 76 that defines a certain rotational angle range. The recess 76 is 
located on the face end of the outer portion of the bushing 66. By means 
of the disk 74 in combination with the recess 75 and the arm 75 of the 
disk, the shaft 64 is accordingly rotatable only within the angular range 
defined by the recess 76. It is rotated via the adjusting lever 69, which 
by means of the torsion spring 73 and the lever 70 is coupled to the shaft 
64 but which is capable of moving through a very much larger rotational 
angle than the shaft 64, because the spring 73 allows it to overrun, or 
move freely, after lifting from the arm 72. If the shaft 64 rotates, then 
the bell crank 53 is moved, via the actuating arm 62, by this particular 
rotational amount, taking the gear ratios into account. The annular slide 
18 is then correspondingly adjusted radially by a defined amount as well. 
The initial position of the adjusting movement can be set by adjustment of 
the bushing 66. 
For the adjustment of the annular slide, the adjusting lever 69 is coupled 
to the adjusting lever 35 and can be moved synchronously by the adjusting 
lever 35. The result is an automatic adjustment of the annular slide 18 as 
a function of the load range indicated by the adjusting lever 35. 
Depending on the intended use of the second control groove of the groove 
51, it is then possible, with a restriction to the sliding range, for 
instance, to divert a throttled fuel bypass flow from the pump work 
chamber 6 whenever the outlet opening 16 comes to communicate with the 
rectangular groove 51. Correspondingly, the pumping rate of the pump 
piston to the injection locations is then reduced during idling, and quiet 
idling can be attained with the quiet-idle device embodied in this way. At 
higher-load positions of the adjusting lever 35, the rectangular groove 51 
or rectangular grooves can then be rotated into the turned-off position, 
via the adjusting lever 69 of the torsion device 52. In a known manner, 
the grooves are disposed on the annular slide in accordance with the 
number of pump piston pumping strokes, so that for example when there are 
two outlet openings 16 the number of grooves 51 can be reduced by half. 
This is possible, however, only if the number of pumping strokes is an 
integer; in the case of 5-cylinder injection pumps, for instance, there 
must be no more than a single outlet opening 16, and five rectangular 
grooves 51 must correspondingly be provided. With the torsion device 
described, however, other control principles that are controlled with a 
rotation of the annular slide can be attained. In that event, the second 
control edge can also be provided in some other manner than that shown. A 
plurality of control openings, offset from one another in the rotational 
or axial direction, on the pump piston or annular slide can then be 
provided, for which the control effectiveness is varied by rotating the 
annular slide. 
FIG. 4 shows a second exemplary embodiment, which in principle is similar 
to the exemplary embodiment of FIG. 2. Here, however, the ball head 55', 
which corresponds to the ball head 55 of FIG. 2, is secured to an 
adjusting bolt 78 that is tightly guided in an inner bore 65' of a bushing 
66' inserted into the pump housing. The adjusting bolt 68 is located 
transversely to the pump piston axis and at right angles to a plane within 
which the pump piston axis is located. On the end protruding into the pump 
interior 7, toward the pump piston axis, the bushing 66' has a lateral 
opening 79, and diametrically opposite this opening, in the wall, it has a 
longitudinal slit 80. The end of the adjusting bolt 78 protruding into the 
pump suction chamber 7 has the head 55', which protrudes through the 
opening 79. Also engaging the slit 80 is a guide nose 81, by way of which 
the adjusting bolt 78 is secured against twisting. Adjoining the guide 
nose, the adjusting bolt 78 has a centering gudgeon 82, onto which a 
restoring spring 83, in the form of a spiral compression spring, is 
slipped; the other end of this spring 83 is supported on a spring plate 84 
that is connected to the housing. By means of this spring, the adjusting 
bolt is held with its end located outside the injection pump on a cam race 
86, which in the embodiment shown here is formed integrally on the 
adjusting lever 69'. The adjusting lever 69' is pivotable in a radial 
plane to the axis of the adjusting bolt and has a right-angle bend serving 
as the cam race 86. Depending on the pivot angle of the adjusting lever 
69', which is pivotable about a shaft 87 attached to the housing, the 
adjusting bolt 78 is displaced inward or outward in the axial direction by 
the amount h. FIG. 5 shows the cam race 86 in a section offset by 
90.degree. from that of FIG. 4. In this exemplary embodiment, as in FIG. 
2, O-rings are possible as seals. The adjusting lever 69' can now be 
coupled to the adjusting lever 35, in an analogous manner to the exemplary 
embodiment of FIG. 2. By means of the right-angle bend, the adjusting 
lever 69' can be rotated an arbitrary distance without displacing the 
adjusting bolt 78 beyond the intended extent. By interposing spacer rings 
in the bearing of the adjusting lever 69', a desired initial position of 
the adjusting bolt 78 can easily be established. 
Instead of the above-described actuation of the adjusting bolt 78 of FIGS. 
4 and 5, the adjusting bolt 78 can also be actuated by a lever 88, which 
is supported on a shaft 89 secured on the outside of the fuel injection 
pump housing and acts with one lever arm 90 axially resting upon the 
adjusting bolt. The other lever arm 91 is in contact with a cam race 92, 
this contact being assured by the restoring spring 83. The cam race 92 is 
connected to the adjusting lever 35 and can for instance be embodied 
analogously to the embodiment of FIGS. 4 and 5. In practical terms, this 
is a technological equivalent to the embodiment of FIG. 4. 
A fourth exemplary embodiment is shown in FIG. 7. Here, in a modification 
of the exemplary embodiment of FIG. 4, the adjusting bolt 78' is again 
supported in the bushing 66'. The head 55' is again secured at the end of 
the adjusting bolt 78' and protrudes through an opening 79' toward the 
pump piston axis and is coupled with the annular slide 18. The adjusting 
bolt 78' is again guided by the nose 81 in the slit 80. Deviating from the 
embodiment of FIG. 4, the restoring spring 83' is now disposed on the 
other end of the adjusting bolt 78'. To this end, the inner bore 65' is 
changed, after the seal 93, into a bore segment 94 of larger diameter, in 
which a cup 95 is guided. The outside of the bottom of the cup is provided 
with a spherical element 96, which comes to rest on the cam race 86 of the 
adjusting lever 69'. The end of the adjusting bolt 78' comes to rest on 
the inside of the cup bottom. The end of the adjusting bolt is provided 
with a head 97; the restoring spring 83' is supported between this head 
and the bushing, at the transition between the inner bore 93 and the bore 
segment 94, and keeps the adjusting bolt 78' in contact with the cup 95. 
In this exemplary embodiment, the adjusting bolt 78' is in principle moved 
in the same manner as the adjusting bolt 78 of FIG. 4. Once again, a 
variant in its actuation is possible, as shown in FIG. 6. Advantageously, 
the restoring spring 83' is now located outside the interior of the fuel 
injection pump, so that in the event of spring breakage, for example, no 
elements that could cause damage can get into the interior of the fuel 
injection pump, which would be dangerous in such a case because regulation 
could be blocked or that essential parts might be destroyed. The spring 
83' is also accommodated in a protected manner by being encapsulated by 
the cup 95. A similar protective device for the exemplary embodiment of 
FIG. 4, for example, in which the spring is also located outside the 
housing, can be provided in the form of a capsule 97 that is held on the 
lever 70 and encompasses both the end of the bushing 66 and the torsion 
spring 93. This embodiment again has the advantage that elements that are 
vulnerable to breakage are located outside the fuel injection pump. 
However, this version according to FIG. 2 has the disadvantage, as 
compared with the version of FIGS. 4 and 7, of having more moving parts, 
which must be adjusted and assembled and which furthermore entail greater 
transmission play. 
The foregoing relates to preferred exemplary embodiments of the invention, 
it being understood that other variants and embodiments thereof are 
possible within the spirit and scope of the invention, the latter being 
defined by the appended claims.