JPH0536632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fuel injection pump for an internal combustion engine, which has a pump piston that reciprocates within a pump cylinder and limits a pump working chamber. The working chamber is connectable with the fuel injection conduit during at least a portion of the delivery stroke of the pump piston, and the pump working chamber is spring-loaded into the cylinder via an extraction conduit that includes a throttle and a rotary slide. It relates to a type that can be connected to a take-off chamber formed in the cylinder by means of a compensating piston guided by.

BACKGROUND OF THE INVENTION In the fuel injection pump known from German Patent No. 1807554, a compensation line is provided in which an outlet line is located coaxially with respect to the pump piston axis from the pump working chamber, also coaxially with respect to the pump piston. It extends to the extraction chamber in front of the piston. A rotary slider whose axis is coaxial with the drain passage is also disposed within the drain conduit, and this rotary slider is operated by a link mechanism disposed on the fuel injection pump.
Such a device is used as a quiet operation device to obtain quiet operation of an internal combustion engine, and it gently shapes the combustion process, especially in a compression ignition internal combustion engine that injects fuel directly into the combustion chamber. This is used to prevent too much fuel from accumulating in the combustion chamber between the start of ignition and the end of ignition, resulting in rapid combustion. Such combustion results in a rapid pressure increase and, in turn, significant noise generation during combustion. A problem with this known device is that the shaft for actuating the valve must additionally be precisely guided and tightly fitted in the drain line. Moreover, this perpendicularly located shaft requires a large amount of space and is disadvantageous in that it is necessary to provide an expensive linkage mechanism for operating the shaft.

Problems to be Solved by the Invention The present invention seeks to solve the problems of the high cost, large space, and need for attached mechanisms in the arrangement of the shaft for operating the valve in the known devices.

Measures for Solving the Problems The measures according to the invention for solving the above-mentioned problems provide that the compensation piston itself is formed as a rotating slider and that a rotation device is arranged to allow an axial sliding of the compensation piston. provided, and in which at least one control opening is formed in the outer wall of the compensating piston and is permanently connected to the removal chamber;
It is provided that the control opening can be brought into overlap with a connection of a withdrawal conduit extending from the pump working chamber to the cylinder.

Embodiment According to the embodiment of claim 2, the rotary mechanism or valve for shutting off the withdrawal conduit is arranged coaxially with the compensation piston to the pump piston axis, so that the conventional combustion It is also very advantageous to be able to attach it to an injection pump. This applies in particular to distributor fuel injection pumps of reciprocating piston construction, in which the end faces of such pumps can be connected to the pump work chamber, making it possible to attach auxiliary devices such as those described above.

The embodiment according to claim 3 allows a very compact construction. Furthermore, according to the embodiment of claim 5, the connection to the pump working chamber can be controlled independently of the axial position of the compensating piston.

In accordance with a further embodiment of the invention, the pressure in the withdrawal chamber is drained after the connection to the pump working chamber is interrupted, so that in this off state the compensating piston is freed from leakage fuel. It is ensured that it cannot be moved into an undesired lifting position. If such a piston malfunction occurs, when the compensation work is restarted, which is normally done during idling, as is known, the stored fuel that has not been discharged will cause an instantaneous large misfit. I would probably end up doing that.

Furthermore, according to the embodiment described in claim 7, the drain conduit of the extraction chamber is controlled to open immediately after the connection to the pump working chamber is closed.
The rotational momentum of the compensating piston is extremely small.

Effect Next, the effect of the above technical means will be explained using FIG. When the device is switched on, via the control opening 19 of the compensating piston 16, fuel from the pump working chamber 3 is introduced into the take-off chamber below the piston and lifts the piston, thereby increasing the pressure of the injected fuel from the pump. Compensate for. When the device is subsequently switched off, the fuel in the removal chamber is drained by rotation of the compensating piston 16, which is returned to its starting position for the next operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a section of a distributor fuel injection pump. In this case, a pump piston 1 encloses a pump working chamber 3 in a cylinder 2, which pump piston 1 is given a reciprocating pumping movement and at the same time a rotational movement by means not shown; The piston acts as a distributor. Via a distribution groove 4 in the jacket wall of the pump piston 1, fuel is conveyed from the pump working chamber 3 to one of several injection lines 5, which are used to supply the associated internal combustion engine with fuel. They are distributed around the cylinder 2 in accordance with the number of cylinders to be used and are guided to the respective individual injection valves 6. At the end of the injection, fuel is drained from the pump working chamber 3 via a drain line 7 which branches off from the pump working chamber 3 and extends into the pump piston 1, so that during the further stroke of the pump piston this drain line 7 is drained. From the moment when the opening control is carried out, the displaced fuel is led out not into the injection line 5 but via the drain line 7.

Furthermore, an outlet line 9 leads out of the pump working chamber 3 in the longitudinal direction of the pump piston 1. This extraction conduit 9 is connected to the casing 1 of the fuel injection pump.
The cylinder 15 of the quiet running device 14 is connected to the cylinder 15 of the quiet running device 14 through a hollow screw 10 which is screwed coaxially to the pump piston axis into the head of the pump 2 and serves to fix the quiet running device 14 to the housing 12 of the injection pump. You are guided inside. A compensating piston 16 is tightly guided in this cylinder 15, and the end face of this compensating piston 16 allows the cylinder 15 to
A take-out chamber 17 is closed inside. A portion of the extraction conduit 9 passes through a compensating piston 16 , which has a longitudinal groove 19 formed as a control opening in the outer surface of the compensating piston 16 .
0 to an axial blind bore 21 starting from the end face of the compensating piston 16 that delimits the removal chamber 17 . In a given rotational position of the compensating piston 16, the longitudinal groove 19 is connected to the connection of the outlet line 9 to the cylinder 15, regardless of the stroke position of the compensating piston 16.

Due to the longitudinal groove 19 formed in the compensating piston 16, the compensating piston 16 has the function of a rotary slide in addition to its function as a movable wall of the fuel storage device. The end of the compensating piston 16 opposite the take-off chamber 17 projects into the spring chamber 23 and is provided with a shaped part 24 .
4 projects into a corresponding and adapted recess in the spring receiver 25. The return spring 2 is placed in the spring receiver 25.
6 is supported, and the opposite side of the return spring 26 is supported by the opposite end faces of the spring chamber 23. A pin 29 is guided coaxially to the axis of the compensating piston 16 and the spring chamber 23 in a guide hole 28 of the cover 27, which is to close the spring chamber 23; It has a small pin 30 that engages in a notch 31. This small pin 30 is located in the end face 32 of a collar 33 of the pin 29, which together with a portion of the cover 27 fixes the pin 29 in position in the axial direction.
Furthermore, the pin 29 has a blind hole 3 starting from its end face 32.
4, and the molded member 24 is in the blind hole 34,
The spring receiver 25 can be pushed in until it comes into contact with the end surface 32 of the collar 33. The length of the small pin 30 is such that the small pin is in a fitted connection with the spring receiver 25 at any movement position of the spring receiver 25;
Provision is thereby made to ensure that the compensating piston 16 is rotated via a lever 39 connected to a pin 29 outside the housing of the quiet operation device 14. Another extreme position of the spring receiver 25 is provided by the bottom of the spring chamber 23 or by the part of the bushing 35 provided for guiding the compensating piston 16 and having the cylinder 15 that projects into the spring chamber 23. stipulated. The bushing 35 is adjustable to adjust or limit the stroke of the compensating piston 16 and has suitable openings for connecting the outlet conduit 9 and the flute 19. The above molded member 24, spring receiver 25, pin 2
9, the small pin 30 and the bush 35 form a rotating device for the compensating piston 16.

A drain line 36 leads out of the spring chamber 23 and a drain line 37 leads out of the cylinder 15 , the connection of which leads into the axial blind hole 21 of the compensating piston 16 in its second rotational position. A connection with the removal chamber 17 is possible by means of a recess formed as a second longitudinal groove 38 to be connected with. In this second rotational position, the other recess, i.e. the longitudinal groove 19, in the compensating piston 16
does not overlap with the connection port of the extraction conduit 9 (see FIG. 2).

The operation of this quiet operation device 14 is as follows. When this device 14 for quiet operation is switched on, for example when the internal combustion engine is idling, in order to create a gentle combustion process, the pump piston 1
During the delivery stroke of the pump piston, a portion of the fuel quantity delivered by the pump piston is conveyed to the cylinder 15 via the withdrawal conduit 9. In this on-state, the compensating piston 16 is in a rotational position in which its longitudinal groove 19 overlaps the connection opening of the extraction conduit 9, so that fuel flows from the pump working chamber 3 to the throttle 20 and the blind hole 21.
It is designed to reach the inside of the take-out chamber 17 via. The pressure created in this withdrawal chamber 17 creates an axial movement of the compensating piston 16, so that the corresponding withdrawn fuel is stored in the withdrawal chamber 17. In this case, the throttle 20 cooperates with the absolute length of the delivery period of the compensating piston 16, which is given by the stroke H of the compensating piston 16, to define the amount of fuel to be extracted.

By turning the lever 39, this quiet operation device 14 can be simply switched off and at the same time the removal chamber 1 can be turned off.
7 is connected to the drain conduit 37. In this off state, leakage fuel is thus prevented from collecting in the removal chamber 17 and causing the compensating piston 16 to move into an inadvertent deflected (lifted) position.

FIG. 3 shows a variant embodiment of the rotating device for the compensating piston shown in FIG. In this example, the length of the extraction conduit 9 is extremely shortened, so that the pump work chamber 3 and the extraction chamber 1
7a can be kept as small as possible. Quiet operation device 1 in this case
4a consists of a closing member 40 which is screwed coaxially to the pump piston axis into the head of the housing 12 of the fuel injection pump and seals off the end face of the pump working chamber 3. This closing member 40
A bushing 41 is tightly inserted therein, and the compensating piston 16a is guided in the cylinder 15 with the bushing 41. An end face 42 of the compensating piston 16a closes off a take-off chamber 17a in the cylinder 15. The bushing 41 is fixed in position by a cup-shaped insert 43 screwed coaxially to the axis of the compensating piston 16a, in which the spring chamber 23 is formed. Further, the pin 29a projects into the spring chamber 23 through the bottom of the insert 43. This pin 29a is rotated by means of an adjustment lever 39a arranged on its outer part. A protrusion 44 is arranged on the end face of the pin 29a facing the compensating piston 16a, and this protruding part 44 is connected to the compensating piston 1.
6a projects into a correspondingly formed groove 45 corresponding to the end face of the head 46 projecting into the spring chamber 23, allowing a constant axial movement of the compensating piston 16a and during this movement the compensating piston 16a. 16a
and are always in a mated connection state. Pin 29a is surrounded by a return spring 26 supported between the inner bottom of insert 43 and the end face of head 46.

A take-out conduit 9a extends from the pump work chamber 3 to a bush 41, and at its connection point it connects to the bush 4.
1 is formed with an aperture 47 forming a radial connection to the cylinder 15 . The compensating piston 16a is formed with a longitudinal groove 48 as a control opening starting from its end face 42, and the pin 29
In the corresponding rotational position given by a, this longitudinal groove 48 overlaps the diaphragm 47. In this position, the quiet operation device is in the on state and operates in the same manner as in the previous embodiment. When the pin 29a is rotated to stop the quiet operation device, the vertical groove 4
8 comes to overlap the radial hole 49 in the wall of the bushing 41, and the aperture 47 is closed. A drain conduit 37a is always connected to this radial hole 49, and this drain conduit 37a is also connected to the spring chamber 23 via another drain conduit 36. In this rotational position, the removal chamber 17a is drained, thereby ensuring that the function of the quiet operation device at the time of switching on is not prevented by the collected leakage fuel. The central arrangement of this embodiment has the great advantage that the extraction conduit 9a can be made very short.

Effects In the fuel injection pump according to the invention, the compensating piston simultaneously serves as a valve closing mechanism (rotary slider), and for this purpose the piston requires very few structural changes, and the rotating device for the piston also Simple and easy to manufacture. Therefore, according to the present invention, each of the above-mentioned problems is effectively solved.

[Brief explanation of drawings]

The drawings show two embodiments of the present invention, in which FIG. 1 is a partial vertical sectional view showing the head portion of a fuel injection pump according to the first embodiment of the invention, and FIG. 2 is a compensation diagram of FIG. 1. cross-sectional view of the control section of the piston;
FIG. 3 is a partial longitudinal sectional view of a second embodiment of the invention, and FIG. 4 is a cross-sectional view of the control section of the compensating piston of FIG. 1...Pump piston, 2...Cylinder, 3...
...Pump work chamber, 4...Distribution groove, 5...Injection conduit, 6...Injection valve, 7, 36, 37, 37a...
Drain conduit, 9, 9a... Removal pipe, 10...
Hollow screw, 12...Casing, 14, 14a...
...Quiet operation device, 15...Cylinder, 16,1
6a... Compensation piston, 17, 17a... Take-out chamber, 19, 38, 48... Vertical groove, 20, 47...
Aperture, 21, 34... Blind hole, 23... Spring chamber, 2
4... Molded member, 25... Spring receiver, 26... Return spring, 27... Cover, 28... Guide hole, 2
9,29a...Pin, 30...Small pin, 31...
Notch, 32, 42...End face, 33...Brim, 3
5, 41... Bushiyu, 39, 39a... Lever,
40...Closing member, 43...Insert, 44...Protrusion, 45...Groove, 46...Head, 49...Radial hole.

Claims (1)

[Claims] 1. A fuel injection pump for an internal combustion engine, comprising:
It has a pump piston 1 that reciprocates in a pump cylinder 2 and delimits a pump working chamber 3, which can be connected to a fuel injection conduit 5 during at least part of the delivery stroke of the pump piston 1. and the pump working chamber 3 is connected to the throttles 20, 4
7 and rotary slides 16, 16a, spring-loaded cylinder 1
a take-off chamber 17, formed in said cylinder 15 by a compensation piston 16, 16a guided in said cylinder 5;
17a, the compensating pistons 16, 16a themselves are connected to the rotating slider 1.
A rotary device 24, 25, 30, 29, 35 is arranged, which is designed as 6, 16a and enables an axial displacement of the compensating piston 16, 16a, and also on the outer wall of the compensating piston 16, 16a. is formed with at least one control opening 19, 48 which is permanently connected to the withdrawal chamber 17, 17a, which control opening is connected to the connection of the withdrawal conduit 9, 9a extending from the pump working chamber 3 to the cylinder 15. characterized in that it can be brought into an overlapping state of
Fuel injection pump for internal combustion engines. 2. A guide member is arranged on the end face of the compensating piston 16 facing away from the removal chamber 17, which guide member is connected in the direction of the axis of the compensating piston with a correspondingly configured member of the rotating device. , which are fitted and connected in the rotational direction.
Fuel injection pump as described in section. 3. Claim in which the rotating device has a rotatable pin 29 arranged coaxially with respect to the axis of the compensating piston 16, which pin 29 is surrounded by a return spring 26 that loads the compensating piston. The fuel injection pump according to the range 2 above. 4. The guide member is formed into a prismatic shape.
A fuel injection pump according to claim 2. 5. The fuel injection pump according to claim 1, wherein the compensating piston 16 is provided with at least one longitudinal groove 19, 38 as a control surface. 6. The fuel injection pump according to claim 5, wherein the drain conduit 37 branches off from an area of the cylinder 15 that overlaps the longitudinal area of the longitudinal grooves 19, 38. 7. A second longitudinal groove 38 is formed in the compensating piston 16 and is constantly connected to the take-out chamber 17;
Claim 6, wherein in the rotational position of the compensating piston 16 in which the removal conduit 9 is to be closed, this second longitudinal groove 38 is connected to the drain conduit 37.
Fuel injection pump as described in section. 8. The fuel injection pump according to claim 1, wherein the compensation piston is positioned axially parallel to the axis of the pump piston 1. 9 The casing receiving the compensating piston 16a and the rotating device for the compensating piston is located in the pump working chamber 3.
9. A fuel injection pump according to claim 8, characterized in that it is formed from a closing member (40) inserted into the casing (12) of the fuel injection pump. 10. The fuel injection pump according to any one of claims 1 to 9, wherein the fuel injection pump is a distribution injection pump having a reciprocating piston structure.