JPH0577857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application A fuel injection pump for an internal combustion engine according to the invention, comprising an injection quantity adjustment mechanism and a movement in a cylinder against the force of a return spring in relation to an operating parameter. an adjusting device with a possible adjusting piston;
A detection surface is arranged on the adjustment piston, and the detection surface changes the stroke limit of the injection amount adjustment mechanism by moving the detection member in the axial direction when the adjustment piston moves. related to things.

Prior Art In this type of fuel injection pump, which is known from German Patent Application No. 2847572, the detection surface is a two-dimensional characteristic area that is imaged on a three-dimensional cam, and the characteristic area is defined by the characteristic area. The full-load stop, which acts as an injection quantity adjustment mechanism, is then adjusted as a function of rotational speed and air pressure. By adjusting this full load stopper, at each operating point, the black smoke generation limit of the circular combustion engine is not exceeded.
In addition, the maximum injection quantity is limited so that the maximum possible rotational moment is maintained.

The fuel injection pump correction work, that is, the adjustment operation and manufacturing error compensation method, brings the operating operating point of the fuel injection pump (and the fuel injection amount adjustment characteristic curve at full load) closer to the operating operating point of the internal combustion engine to which it belongs. This is how it is done. In order to approach this operating operating point, it is necessary to perform a number of adjustment operations, such as detecting the operating operating point to be adjusted and then comparing the detected value with the set value. Such a relatively complicated and time-consuming correction operation of the fuel injection pump does not meet the requirements for making the manufacturing process of the fuel injection pump flexible and, above all, automated.

Problem to be Solved by the Invention The problem to be solved by the invention is to improve the fuel injection pump of the type mentioned at the outset and to provide a fuel injection quantity adjustment mechanism for a large number of adjustment characteristics with a low technical outlay. The aim is to be able to adjust the stroke limit profile to suit different internal combustion engines.

Means for Solving the Problems In order to solve the aforementioned problems, the present invention provides that the adjusting piston can be fixed in different rotational positions, and that a plurality of detection cams are arranged on the outer wall of the adjusting piston. The detection cams are arranged parallel to the axis of the piston and have a stepped characteristic between them.

Embodiment FIG. 1 shows a fuel injection pump for an internal combustion engine, for example a distribution injection pump. The pump has a regulating lever 2 which is adjusted by means of a governor (not shown) against the force of an adjusting spring 3 and thus operates a fuel quantity regulating mechanism. That is, in this function, the speed regulating lever 2 can also be regarded as a fuel amount adjusting member. The regulating lever 2 rests on an adjustable full-load stop 5 in the full-load state. Full load stopper 5
is arranged at one end of the two-arm lever 6 in this embodiment, and the other end of the two-arm lever 6 is in contact with the detection pin 7. The detection pin 7 is guided through a hole 8 and projects into a cylinder 9 of the casing 1 of the fuel injection pump.

An adjusting piston 11, which can be fixed in three rotational positions, is guided in the cylinder 9 in a sealed manner. The end face of the adjusting piston 11 together with the cylinder 9 forms a working chamber. This work room has opening 1
6 is permanently connected in the region of end face 15 to a chamber 17 which is filled with pressure medium. Room 17
The pressure is controlled in relation to the rotational speed. In this embodiment, the chamber 17 is the suction chamber of the fuel injection pump, which is filled with fuel, the fuel supply being provided by the fuel pump 18 . The fuel pump 18 sucks fuel from a storage tank 19 , the transport side of which can be unloaded by means of a pressure control valve 20 . As a result, the rotational speed-dependent pressure in chamber 17 as suction chamber is regulated.

The cylinder 9 opens into a leakage chamber 23 which is closed by a lid 24 on the side opposite the working chamber. Lid 24
An adjusting sleeve 26 is screwed onto the holder and can be secured by a locking nut 27 which can be actuated from the outside. The sleeve bottom 28 has a return spring 3
0 forming a shoulder for one end section.
The other end section of the return spring 30 is connected to the adjusting piston 1
It is supported by the end surface 29 on the back side of 1. The adjusting sleeve 26 is arranged coaxially with the axis 45 of the adjusting piston 11 and has a central screw hole 31 . This central threaded hole 31 cooperates with the external thread of the adjustment pin 33. The adjustment position of this adjustment pin 33 can be fixed by means of a locking nut 34 which can also be actuated from the outside.

Furthermore, as shown in FIG. 2, fine conical teeth 41 are recessed in the end face 29 of the adjusting piston 11. Engaged in this tooth 41 is a fine crown tooth 40 which corresponds to the tooth 41 on the end section of the adjusting pin 33. This allows the adjusting pin 33 to be connected in a form-locking manner to the adjusting piston 11 . At this time, when the pressure in the chamber 17 exceeds the force of the return spring 30, the two parts to be connected are brought into contact with each other.

The detection body 21 is a part of the cylindrical adjusting piston 11 and has three grooves 42, 43, 44 arranged in its outer wall. The side walls 46 of the grooves are arranged parallel to the axis 45 of the adjusting piston 11, and the bottoms of the grooves are each configured as a detection cam 47, 47a, 47b. In this case, these detection cams have a stepped adjustment characteristic with respect to one another. The individual adjustment characteristics and their mutual relationship are harmonized to one another in such a way that the adjustment range provided by the detection cam is as continuous as possible with respect to one another.

The bottom of the groove 43 is a so-called reference detection cam 47.
a, and this reference detection cam 47
a and the detection cams 47 and 47b have inclination angles α1, α2, α3 of the same magnitude in relation to the axis 45. The end section of each detection cam 47, 47a, 47b towards the end face 15 of the adjusting piston 11 is
The bottom of each groove transitions in the radial direction into an annular surface 48 having an outer peripheral configuration such that it transitions into an annular surface 48 without the formation of a step.

Regarding the function of the adjusting pin 33, it should be noted that the adjusting pin 33 acts as a stopper for the adjusting piston 11 and is also provided for rotating the adjusting piston. The return spring 30 increases with the screwing depth of the adjustment pin 33.
The displacement distance of the adjusting piston 11 against the pressure is limited, and therefore the effective length of the detection cams 47, 47a, 47b formed at the bases of the grooves 42, 43, 44 is also limited. In order to adjust the rotational position of the adjusting piston 11, the adjusting piston is connected to the detection pin 7.
is loaded by the high internal pressure of the suction chamber in such a way that it reaches the region of the annular surface 48 . In this case, up to this position, the adjusting piston 11 is in mesh with the tooth row of the toothed end surface 40 of the adjusting pin 33, so that the adjusting piston can also rotate together with the rotation of the adjusting pin 33. In this case, due to this rotation, the adjusting pin 33 moves, acting as a stop, into a correcting position, i.e. into a correcting position in which the annular surface 48 of the adjusting piston 47 no longer coincides with the detection pin 7;
It is brought about.

The functions of the fuel injection pump of the present invention are as follows.

As the rotational speed of the internal combustion engine increases and thus the pressure in chamber 17 increases, adjusting piston 11 moves in the direction of arrow 49 (FIG. 1) against the pressure force of return spring 30. In this case, the contact pin 7 follows the detection surface against which it rests in a force-transmitting connection by the force of the return spring 3 and adjusts the position of the full-load stop 5 by movement in the axial direction. In this way, a predetermined characteristic curve of the fuel injection amount during full-load operation is obtained as a function of the rotational speed.
The appropriate adjustment of the maximum injection quantity position of the fuel quantity regulating mechanism is suitably modified at the respective rotational speed value by the total load regulation provided by the pump structure. This modification takes place in relation to the profile of the detection cams 47, 47a, 47b at the bottom of the respective groove, the return spring 30 and its spring characteristics, and the pressure profile in the chamber 17 over the entire speed range.

[Brief explanation of drawings]

1 is a partial longitudinal sectional view of a hydraulically operable Angleich device according to an embodiment of the invention, and FIG. 2 is a partial sectional view of an adjusting piston with an adjusting pin according to FIG. FIG. 1...Casing, 2...Governing lever, 3...
Adjustment spring, 5... Full load stopper, 6... Two arm lever, 7... Detection pin, 8... Hole, 9... Cylinder, 11... Adjustment piston, 12... End face, 15
... end face, 16 ... opening, 17 ... chamber, 18 ...
Fuel pump, 19...Storage tank, 20...Pressure control valve, 21...Detection object, 23...Leak chamber, 24
... Lid, 26 ... Adjustment sleeve, 27 ... Locking nut, 28 ... Sleeve bottom, 29 ... End surface, 3
0... Return spring, 31... Center screw hole, 33...
... Adjustment pin, 34 ... Locking nut, 40 ... Toothed end surface, 41 ... Teeth, 42, 43, 44 ... Groove, 45 ... Axis line, 46 ... Side wall, 47, 47
a, 47b...detection cam, 48...annular surface, 49
...Arrow, α1, α2, α3...Inclination angle.

Claims (1)

Claims: 1. A fuel injection pump for an internal combustion engine, comprising an injection quantity adjustment mechanism and an adjustment piston movable in the cylinder against the force of a return spring in relation to operating parameters. A detection surface is disposed on the adjustment piston, and the detection surface changes the stroke limit of the injection amount adjustment mechanism by moving the detection member in the axial direction when the adjustment piston moves. In this type, the adjusting piston 11 can be fixed in different rotational positions, and a plurality of detection cams 47, 47a,
47b is arranged on the outer wall of the adjusting piston 11, parallel to the axis of the adjusting piston 11, and the detection cams have a stepped characteristic with respect to each other. fuel injection pump. 2 Each detection cam 47, 47a, 47b has groove 4
It is formed by the bottoms of 2, 43 and 44,
A detection member 7 is in contact with the bottom portion through a power transmission connection,
The fuel injection pump according to claim 1, comprising a reference detection cam 47a and at least one detection cam 47, 47b arranged on both sides of the reference detection cam. 3. It has an adjusting pin capable of varying the start of action of the return spring, the adjusting pin cooperating with a threaded hole in the casing of the adjusting device to come into contact with the adjusting piston, and the adjusting pin 3. Fuel injection pump as claimed in claim 1, characterized in that one end section is connected in a form-locking manner with the adjusting piston (11). 4. Fuel injection pump according to claim 3, wherein the positive-locking connection is formed by a crown tooth 40 of the adjusting pin 33 and a tooth 41 of the adjusting piston 11. 5. The end section of the adjusting pin 33 with the crown teeth 40 and the end section of the adjusting piston 11 with the teeth 41 corresponding to the crown teeth 40 have a conical shape or a flat plate shape. The fuel injection pump according to item 4. 6 One end section of each detection cam 47, 47a, 47b transitions into an annular surface 48, and the detection member 7
is supported on said annular surface 48 of the adjusting device, by rotating the adjusting pin 33 the adjusting piston 11 can be pivoted from one groove to another. The fuel injection pump according to any one of items 3 to 5.