Pneumatic diaphragm control member for a fuel injection device for internal combustion engines

A pneumatic diaphragm control member is proposed for a fuel injection device for internal combustion engines, especially for a boost-pressure dependent full-load stop, wherein the initial and end positions of a push rod provided with a control diaphragm and movable against a resetting spring can be varied, and wherein the effective pressure range is variable by means of separate adjusting means which do not affect one another. The push rod of the diaphragm control member contacts, in the unpressurized starting position, a stop screw mounted in the lid cover, and, in the pressurized end position, is in contact, by means of a counter stop attached to an extension of the push rod and adjustable in the direction of motion of the push rod, with a second end stop arranged in the pressure chamber. Thus, the bias of the resetting spring can be changed by changing the position of a bearing bushing for the push rod, which bushing serves as an abutment.

BACKGROUND OF THE INVENTION 
The invention is based on a pneumatic diaphragm control as described herein 
and finally claimed. Diaphragm control members of this type of 
construction, used in boost-pressure dependent full-load stops, are known, 
for example, from U.S. Pat. No. 4,057,044 and from the publication by 
Robert Bosch GmbH, Stuttgart, Federal Republic of Germany, "Diesel 
Injection Installation Speed Governors for Series-Type Injection Pumps", 
VDT-UBT 210/1 dated Sept. 30, 1975, p. 41, FIG. 91, and a diaphragm 
control member of a similar construction has been known from the 
publication by Robert Bosch GmbH, "Diesel Injection Installation" VDT-UBP 
001/15 dated Apr. 30, 1973, p. 16, FIG. 20, wherein the starting and end 
positions of the push rod, as well as the bias of the resetting spring, 
can be adjusted by separate adjusting members to determine the beginning 
and end as well as the pressure range of the boost-pressure dependent 
correction of the full-load quantity. However, these devices have the 
disadvantage that, in the event of a subsequent correction of the starting 
position, which is frequently necessary to effect the adaptation of the 
full-load quantity without boost pressure, that is, the intake quantity, 
there is also a change in the end position of the push rod and 
consequently in the full-load quantity under full boost pressure, that is, 
the so-called boost quantity, or the effective pressure range. As a 
result, these values must be readjusted after changing the intake quantity 
adjustment. 
OBJECT AND SUMMARY OF THE INVENTION 
The diaphragm control member of this invention as claimed herein has, in 
contrast to the above, the advantage that all three settings for the 
intake and boost quantities, as well as for the pressure range can be set 
and readjusted independently of one another by control members separately 
arranged at the diaphragm control member. Since this diaphragm control 
member contains all of the control members, it can be utilized as a 
standard control member under a great variety of different mounting 
conditions, for example for attachment to a full-load stop that is 
dependent on the boost pressure and effective directly on the push rod. 
Moreover, the control member can likewise be utilized for a stop which 
engages the governor linkage and is mounted on the housing thereof. Any 
additional transmission elements for the control movement need not contain 
any adjusting elements or stops, whereby the construction of the full-load 
stops is considerably simplified. 
By the measures recited in the dependent claims, advantageous further 
developments and improvements of the diaphragm control member indicated 
are made possible. Thus, by means of the new features, an easy 
accessibility of the second end stop is insured, and, due to the fact that 
an end face of a control disk mounted in the partition is utilized as the 
stop surface, a wearproof stop which limits the end position of the push 
rod is obtained, independently of the choice of material for the cover. 
The new features insure a ready accessibility to the adjusting nut that 
serves as the counter stop for the second end stop. In case of a cover 
plate sealed with a lead seal, it is no longer possible to adjust, in an 
unauthorized fashion, the set end position of the push rod (boost 
quantity), whereas the starting position (intake quantity) can be 
subsequently adjusted as desired by the engine manufacturer, without 
varying the other set values. 
The invention will be better understood as well as further objects and 
advantages thereof become more apparent from the ensuing detailed 
description of preferred embodiments taken in conjunction with the 
drawings.

DESCRIPTION OF THE EMBODIMENTS 
Turning now to the drawings, in FIG. 1, the housing 12 of a boost-pressure 
dependent full-load stop 13 is flanged to an input-side end face 10 of a 
fuel injection pump 11. This housing 12 is provided with a pneumatic 
diaphragm control member 14. The control member 14 is attached by means of 
a centering flange 15 of its housing 16 to an end face 17 of the housing 
12 and contains a control diaphragm 19 clamped between the housing 16 and 
a cover 18. The control diaphragm 19 is connected to a push rod 23 movable 
between two end stops 21 and 22. This push rod is guided in a bearing 
bushing 25 which serves simultaneously as an adjustable abutment for a 
resetting spring 24 and is threadedly inserted in the stop housing 16. The 
bearing bushing 25 is threaded into the housing 16 by means of a threaded 
area 26, is vertically adjustable and is secured in the respective 
position by a resilient tongue 28 which is arranged to engage in one of a 
number of detents denoted 27. 
By means of the control diaphragm 19, the interior of the diaphragm control 
member 14 is subdivided into an atmospheric chamber 29 and a pressure 
chamber 31 surrounded by the cover 18. In this manner the pressure chamber 
is supplied with the boost air pressure ambient in the intake manifold of 
the engine via a connecting bore 32. The pressure chamber 31 within the 
cover 18 is subdivided by a partition 33 into two sectional chambers 31a 
and 31b. The first sectional chamber 31a is bounded by the control 
diaphragm 19, and the second sectional chamber 31b is sealed 
pressure-tight by a seal member 34, through which the first end stop, 
formed as a stop screw 21, is threaded and secured in the adjusted 
position by a counter nut 35. 
In the illustrated, unpressurized condition of the stop, an extension 36 
which projects upwardly from the push rod 23, contacts this stop screw 21. 
The second end stop 22, which determines the operating position of the 
push rod 23 assumed under maximum boost pressure, is constituted by the 
end face of a steel disk 37, which serves as the stop surface as shown in 
the drawings. The end stop 22 limits the stroke of a counter stop 38 that 
is attached to the extension 36 of the push rod 23. The counter stop 38 
comprises an adjusting nut, as shown, which is threaded onto the extension 
36 of the push rod 23, which extension is fashioned as a threaded pin. 
In the illustrated position, the adjusting nut 38 is secured by a counter 
nut 39. The steel disc 37, manufactured from tempered spring steel, is 
secured in the intermediate wall 33 by means of annular caulking and thus, 
in the case of a cover 18 produced (for reasons of cost and weight) from 
aluminum, forms a wear-resistant second terminal stop for the push rod 23 
by means of the end face 22. Further, the push rod 23 transmits its 
adjustment motion through a bell crank 41 which is pivotably supported in 
the housing 12 of the full-load stop 13 and into a control rod 42 which 
acts as the supply quantity adjustment member of the injection pump 11. 
The end 41a of the bell crank 41 represents the full-load stop which is 
adjustable in accordance with charge pressure. 
The adjusting nut 38, which serves as the counter stop, has engagement or 
contact surfaces 43 along a rim enlarged with respect to the outer 
diameter of the counter nut 39 and to this area a tool may be attached to 
achieve adjustments. Such a tool can consist, in a compact structure, of 
two nestled, tubular socket wrenches and can be introduced, after removing 
the sealing plate 34, into the second sectional chamber 31b and placed 
over the nuts 38 and 39. The counter stop 38 which cooperates with the 
second end stop 22 determines the position assumed by the full-load stop 
41a under full boost pressure. This point, limiting the maximum power, 
must no longer be adjusted in an unauthorized fashion, and the sealing 
plate 34 is, therefore, provided with a lead seal after setting the 
adjusting nut 38. As can be seen clearly from FIG. 1, it is then still 
possible to adjust the stop screw 21, which serves as the first end stop, 
from the outside to correct the starting position and the position of the 
full-load stop 41a thus determining the intake quantity. If this setting 
of the stop screw 21 is also to be secured against unauthorized 
manipulation, then it is possible to attach a sealing cap, indicated in 
dot-dash lines and denoted by 44, over this screw at the end face of the 
sealing plate 34. 
After removal of a lateral sealing screw 45 in the housing 16 in the area 
beneath the diaphragm control member 14, the bias of the resetting spring 
24 can be varied by rotating the bearing bushing 25, whereby the pressure 
range and thus also the speed range can be shifted. It is to be understood 
that it is in this range that the boost-pressure dependent correction of 
the full-load injection quantity takes place. Accordingly, all points 
determining the characteristic of the boost-pressure dependent correction 
can be set separately from one another and without exerting any mutual 
influence. 
In the second embodiment shown in FIG. 2, the boost-pressure dependent 
full-load stop, here denoted by 13', is flanged to a governor housing 51 
of a centrifugal speed governor 52 and consists essentially of a diaphragm 
control member 14' arranged in the horizontal position as contrasted to 
the diaphragm control member 14 in FIG. 1. 
This diaphragm control member 14' is flanged with its housing 16 directly 
to the governor housing 51, without inter-position of an additional 
abutment housing and merely differs from the diaphragm control member 14 
of the first embodiment in that it has a modified form of the push rod 
23'. This push rod 23' is guided in the bearing bushing 25, and secured 
against twisting or rotation by means of a pin 54 which engages into a 
longitudinal slot 53 provided in the governor housing 51 as shown. The 
push rod 23' carries, at its end which projects into the governor housing 
51, a head-like full-load stop 55 that limits the stroke of a stop lug 56. 
This stop lug 56 extends out of a connecting fishplate 57, which latter 
connects a regulating lever 58 of the centrifugal speed governor 52 with 
the control rod 42 Thus, the stroke of the control rod 42 is limited 
indirectly by limiting the stroke of the connecting fishplate 57. This 
stroke is limited, in the illustrated, unpressurized position of the push 
rod 23', to the full-load position which determines the intake quantity, 
and with a full boost pressure being supplied by way of the connecting 
bore 32 and with a full-load stop 55 correspondingly shifted toward the 
left as viewed in the drawing, this stroke is limited to the full-load 
quantity which determines the boost quantity. Except for the changed shape 
of the push rod 23', all other elements of the diaphragm control member 
14' are identical to those of the diaphragm control member 14 in FIG. 1 
and thus will not be described anew. 
If there is insufficient space in the longitudinal direction of the speed 
governor 52 to attach the boost-pressure dependent full-load stop to this 
particular speed governor, it is also possible to attach, on the governor 
side, a full-load stop equipped with a vertically disposed diaphragm 
control member 14, constructed similarly to the stop in FIG. 1, which acts 
via an angle lever on the stop lug 56 of the connecting fishplate 57. The 
stop lug 56 can, of course, also be connected directly with the control 
rod 42, so that the structural configuration of the governor components 
has no influence on the boost-pressure dependent limitation of the 
full-load quantity. To avoid excessive stress on the full-load stop and an 
overloading of the governor elements, a resiliently yielding drag or 
buffer member is to be inserted in a manner which is known and thus is not 
illustrated in detail, at some location of the governor linkage in the 
power train between the governor sleeve and the full-load stop.