JPH0475389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a fuel injection pump for an internal combustion engine, which is provided with a plunger that reciprocates and simultaneously rotates within a cylinder and is used as a distributor. the amount of fuel pumped from the plunger by controlling the first outlet opening of a depressurization passage provided in the plunger and branched from the pump working chamber by a ring slider moved by a speed governor; a second pressure relief passageway configured to vary the pressure and disposed within the plunger;
The first outlet opening can be controlled by the ring slider after a variable discharge stroke of the plunger, and the second pressure relief passage is provided in the cylinder via the second outlet opening in the plunger. the annular groove through which the second outlet opening is connected to one of the limiting edges of the annular groove;
can be connected to the work room controlled by
It is further provided that the second depressurization channel can be controlled at the end of the delivery stroke of the plunger by means of a ring slide via the third outlet opening.

In the case of such an injection pump, which is known from DE 26 44 698, the first outlet opening and the third outlet opening are controlled by an upper flat end face of the ring slide. is,
In this case, the third outlet opening is controlled to be opened earlier by the first outlet opening during the discharge stroke of the plunger. Furthermore, the third outlet opening is always open in all operating conditions except for the start-up phase, and the connection between the second outlet opening and the pump working chamber takes place only during the relatively small pre-stroke of the plunger, so that Only within this stroke range of the plunger can fuel flow out of the pump working chamber to the depressurizing side. In this way, a constant discharge onset associated with the plunger stroke is maintained. Moreover, when starting the internal combustion engine, the amount of fuel flowing out in an operating range other than the starting is included in the starting increase amount, and at the same time, this can be done by relative rotation of the plunger drive relative to the pump drive. An early adjustment of the start of injection in the start-up phase is achieved relative to the usual injection timing adjustment.

In addition, the Federal Republic of Germany Patent Application Publication no.
In a fuel injection pump for an internal combustion engine with automatic ignition, known from DE 1576310, a device is provided for supplying fuel only to half of the associated internal combustion engine cylinder when the internal combustion engine is idling.
Here, this is done in the case of row injection pumps, in which the plunger provided for no injection at idle has a control lip, which controls the rest of the plunger. It has a shape distinct from the control edge on the plunger and allows zero discharge at idle.
However, such a configuration is not applicable to a distribution injection pump.

The fuel injection pump according to the invention is provided with cutouts on the control edge of the ring slider, which are distributed and arranged in accordance with the selection of the delivery stroke of the plunger, which at least partially prevent fuel pumping.
The recess is assigned to the respective position of the third outlet opening and only to the third outlet opening during the discharge stroke of the plunger, and furthermore, the third outlet opening is assigned to the respective position of the third outlet opening during the discharge stroke of the plunger. It is characterized in that the opening is controlled earlier than the outlet opening of the internal combustion engine, which allows the fuel supply to the part of the cylinder supplied by the fuel injection pump to be carried out at a small cost in the internal combustion engine. Can be cut off when idling. Depending on the adjustment, it is also possible to reduce the amount of fuel injected into these cylinders within the partial load range. At the same time, the remaining cylinders of the internal combustion engine can be supplied with a relatively high fuel injection quantity, for example during idling, in order to compensate for drive losses. By controlling the adjustment of the ring slider by the governor of the fuel injection pump, the cylinders can be switched from a completely shut-off state through a reduced injection state to these cylinders in a relatively high load range. A smooth transition between the cylinder and the unreduced injection state can be achieved.

Advantageous embodiments and improvements of the fuel pump according to the invention are possible with the measures specified in the dependent claims.

For example, the embodiment according to claim 2 provides a simple means of determining when a reduction in fuel injection no longer takes place due to an increasing load.

The invention will be explained below with reference to the exemplary embodiments shown.

A plunger barrel 3 is installed in the casing 1 of a fuel injection pump of the distribution type, which is schematically shown in FIG.
The plunger 4 is fitted into the cylinder 2 of the plunger barrel 3. A plunger 4 forms a pump working chamber 5 at the closed end of the cylinder 2 and is moved in a reciprocating and simultaneous rotational manner in a known manner by means of elements not shown. The pump working chamber of the pump is connected to a suction chamber 9 during the suction stroke of the plunger 4 via a longitudinal groove 7 arranged in the peripheral wall of the plunger and through holes 8 extending through the plunger barrel 3 in the casing.
Fuel is supplied from The suction chamber 9 is the delivery pump 1
Fuel is supplied from a fuel storage chamber 12 via 1. By means of the pressure control valve 13, the pressure in the suction chamber 9 is controlled in a known manner as a function of the rotational speed, so that as the rotational speed increases, the pressure in the suction chamber increases.

A first depressurization passage 1 in the plunger from the working chamber 5
5 is guided, and the depressurization channel connects with the pump suction chamber 9 via a first outlet opening 16 in the lower plunger part which extends from the plunger barrel 3 into the suction chamber 9 . first outlet opening 16
is controlled by a ring slider 17 which is slidable along the plunger. A radial hole 18 branches from the depressurizing passage 15 toward the vertical groove 7, and when the hole 18 communicates with the vertical groove 7, the suction chamber 9 and the working chamber 5 are connected by the hole 8. be done.
Further, in the portion of the plunger 4 that protrudes into the plunger barrel 3 from the pressure relief passage 15, a horizontal hole 19 is formed.
branch out, the transverse bore opening into a longitudinal groove 20 which serves as a distribution groove and cooperates with a discharge conduit 21 arranged evenly distributed on the circumferential wall of the plunger, said discharge conduit 21 They are arranged in accordance with the number of cylinders supplied to the engine, and the discharge lines are successively connected to the distribution grooves 20 during the compression or discharge stroke of the plunger. During its rotation, the plunger therefore acts as a distribution member for the fuel pumped by the pumping movement of the plunger into the individual delivery conduits. The delivery lines lead to the individual cylinders of the internal combustion engine via delivery valves and injection valves, which are not shown. This ensures that during the discharge stroke of the plunger 4, as long as the first outlet opening 16 remains closed by the ring slide 17, fuel is injected via the fuel in the first depressurization channel 15. It is forced into the nozzle.

The ring slider engages in a cutout 25 of the ring slider by means of a head 24 and a shaft 26.
It is moved on the plunger 4 by means of a speed governor (not shown) via an adjusting lever 23, which can be pivoted about, e.g. as a function of load and rotational speed. In this case, when the ring slide 17 is moved downwards, the first outlet opening 16 is always controlled to open early during the delivery stroke of the plunger and the pump working chamber 5 is always depressurized early and at this early stage. After the transfer, fuel is no longer delivered under pressure into the pressure delivery conduit 21. The first depressurization channel serves in this case both for filling the pump work chamber with fuel during the suction stroke and for delivering the quantity of fuel to be injected and for depressurizing at the end of a given injection. If the ring slider 17 is in the upper position, the first outlet opening 16 remains maximally closed during the entire discharge stroke of the plunger, so that the maximum fuel quantity is reached for injection. Such an upper position is
Corresponds to the starting position of the internal combustion engine.

Furthermore, the plunger is provided with a second pressure relief passage 28 having a second outlet opening 29 provided in the plunger, said second outlet opening opening into the inside of the plunger barrel and It cooperates with an annular groove 30 arranged on the circumferential surface of the cylinder 2. The annular groove 30 also always connects to the first pressure relief channel 15 via a transverse channel 31 formed in the plunger.
is connected to. The other end of the second depressurization passage 28 opens into a third outlet opening 32 in the plunger, which in the illustrated embodiment is coplanar with the first outlet opening 16 and aligned with the axis of the plunger. is located perpendicular to. The third outlet opening 32 is thereby also controlled by the ring slide 17.

Furthermore, as can be seen in FIG. 2, which is shown in cross section along a plane perpendicular to the axis of the plunger, the ring slider 17 has four notches, which in the illustrated embodiment are evenly distributed on the circumference of the plunger. It has a notch 34. Furthermore, as can be seen from the drawings, if the first outlet opening 16 in the plunger is not in communication with one of the aforementioned cutouts 34, the third outlet opening 3 in the plunger
2 is always in communication with one of the notches 34. In short, in the position shown, the plunger is in the discharge stroke when the third outlet opening 32 is in communication with one cutout 34, which is the case when the third outlet opening 32 is in communication with another cutout 34. The same goes for me.

The fuel injection pump described above operates as follows. For supplying an eight-cylinder internal combustion engine, the fuel injection pump has eight delivery lines 21 distributed over the circumference. This causes the plunger to carry out eight delivery strokes per rotational speed, during which one of the fuel delivery conduits is injected with fuel insofar as the ring slide 17 closes the first outlet opening 16. Exhale. However, in the illustrated embodiment of the pump according to the invention, already at an early stage:
As soon as the third outlet opening 32 communicates with one cutout 34, the pump working chamber is divided into the first depressurization channel 15, the transverse channel 31, the annular groove 30, the second depressurization channel 28 and the second depressurization channel 28. 3 through the depressurization opening 32 of the suction chamber 9
Pressure is removed to Depending on the position of the ring slide 17, the fuel supply to the corresponding discharge line 21 is therefore completely shut off, especially at low loads. In the case of a load position of the ring slide corresponding to idling of the internal combustion engine, the third outlet opening 3
2 opens simultaneously with the start of the discharge stroke of the plunger. When the delivery stroke has elapsed further, the first outlet opening 16 is also opened by the upper edge of the ring slide 17 and the pump working chamber 5 is therefore closed to this outlet opening 16.
Pressure is also removed through the Furthermore, after the discharge stroke,
First, the second outlet opening 29 is taken out of communication with the annular groove 30 and then closed by the wall of the cylinder 2. The pump working chamber 5 remains connected to the suction chamber via the first outlet opening 16 until the end of the discharge stroke of the plunger. This prevents injection from occurring.

In the case of the suction stroke that follows, the pump working chamber is filled with fuel via the bore 8, the longitudinal groove 7 and the radial bore 18, and in the case of the discharge stroke that follows, the plunger 4 is now filled with fuel. The third outlet opening 32 is rotated insofar as it lies precisely between the two cutouts 34, and this also applies to the first outlet opening 16. In this case, there is no early start control of the pump work chamber, so that the fuel is pumped in the usual manner into the corresponding fuel delivery line.

With this arrangement, inter alia, the delivery of the respective second delivery stroke is blocked for idling, so that only half of the cylinders of the internal combustion engine are supplied with fuel during idling. The cylinders driving the internal combustion engine are thus operated at a higher load, for example twice as much, than they would be in normal operation without cylinder shutoff. The relatively high fuel demand of the cylinders operated for this purpose is automatically adjusted by the governor so that the ring slide 17 occupies a relatively high position. With an internal combustion engine operated in this way, even fuel injection and improved combustion are achieved for idling of the internal combustion engine, leading to fuel savings and a reduction of pollutants in the exhaust gas.

In the embodiment according to FIG. 1, the plunger requires a stroke h _FE starting from bottom dead center until the first outlet opening 16 is opened by the ring slide 17 . Furthermore, starting from the bottom dead center, the plastic gear requires a stroke S _x until the third outlet opening 32 communicates with the cutout 34 . Furthermore, plunger 4
starts from bottom dead center and travels until the second outlet opening 29 no longer communicates with the annular groove 30.
Requires h _vx . Such a dimensional distribution is illustrated in FIGS. 4 and 5 by the plunger movement curve over the rotation angle α. In this case, FIG. 4 shows the idling state. This FIG. 4 also shows a stroke corresponding to the stroke required by the plunger starting from the bottom dead center until the annular groove 37 in the circumferential wall of the plunger, which is connected to the longitudinal groove 7, no longer communicates with the bore 8. h _v is shown. The annular groove 37 has the task of maintaining the connection between the suction chamber and the pump working chamber 5 even if the longitudinal groove 7 no longer communicates with the bore 8 due to the rotation of the plunger. Only after the first pre-stroke h _v is such a connection broken, independent of the rotational position of the plunger. Such a pre-stroke h _v is the fourth
The same is maintained in the diagram and the diagram in FIG. The realization of such a pre-step is not absolutely necessary for the implementation of the invention described above. The following can be seen from the diagram in FIG. 4 for the idling conditions of the internal combustion engine. The stroke h _FE is smaller than the stroke h _vx , which means that the pressure relief through the first outlet opening 16 is such that the second pressure relief passage 28 passes through the second pressure relief outlet opening 2
9 before it is disconnected from the pump working chamber by closing. Furthermore, it can be seen that a discharge stroke S _x −h _v is provided before the third outlet opening 32 is controlled to open. In this case, the stroke S _x is smaller than the stroke h _vx , which is already clear from the comparison with the stroke h _FE . However, the discharge stroke S _x −h _v
is so small that it is not sufficient for the discharge into one of the discharge conduits 21, but for the pressure build-up and partial lifting of the respective discharge valve.

The stroke is caused by the lifting of the ring slider 17.
The expansion of S _x results in a slowly rising discharge component in the cylinder selected for cutting at idle. This results in a continuous transition in the partial load range. Then, at the latest, the dimension of stroke S _x becomes larger than the dimension of stroke h _vx at full load. In this case, the second outlet opening 29 is closed before the third outlet opening 32 is opened by the cutout 34. This ensures that the entire amount delivered from the plunger up to the opening control of the first outlet opening 16 is injected.

In the first embodiment according to FIG. 1, the first outlet opening 16 and the third outlet opening 32 are arranged in the same plane perpendicular to the plunger axis.
Such assignments indicate the configurations actually implemented, but the present invention is not limited to such configurations. In the embodiment shown in FIG. 3, the third outlet opening 32 is provided by the upper end face of the ring slide 17', which is formed in the same place and in the same manner as in the embodiment according to FIG. It will be done. In this embodiment, however, the first outlet opening 16' opens slightly deeper and cooperates with an inner ring groove 39 in the ring slide 17'. The inner ring groove 39 has a radial hole 40
It is connected to the pump suction chamber via.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a first embodiment of an injection pump according to the present invention, FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, and FIG. 3 is a longitudinal cross-sectional view showing a second embodiment. , FIG. 4 is a diagram showing the assignment of the control edge of the first embodiment to the plunger movement curve for idling conditions, and FIG. 5 is a diagram showing the assignment of the control edge to the plunger movement curve for full-load operation. It is a diagram. 1... Casing, 2... Cylinder, 3... Plunger barrel, 4... Plunger, 5... Pump working chamber, 7... Vertical groove, 8... Hole, 9... Suction chamber, 11... Delivery pump , 12...fuel storage room,
13... pressure control valve, 15... pressure relief passage, 16,
16'...First outlet opening, 17, 17'...Ring slider, 18...Radial hole, 19...Horizontal hole, 20...Vertical groove, 21...Discharge conduit, 23...
... Adjustment lever, 24 ... Head, 25 ... Notch, 26 ... Shaft, 28 ... Pressure relief passage, 29 ... Second outlet opening, 30 ... Annular groove, 31 ... Horizontal passage, 34 ...Notch, 37...Annular groove, 39
...Inner ring groove, 40...Radial hole.

Claims (1)

[Claims] 1. A fuel injection pump for an internal combustion engine, which is provided with a plunger 4 that reciprocates and simultaneously rotates within a cylinder and is used as a distributor,
Furthermore, the first outlet opening of the depressurizing passage 15 provided in the plunger and branched from the pump working chamber 5 is controlled by a ring slider 17 moved by the injection pump governor in the plunger. a second depressurization passage 28 arranged in the plunger and adapted to vary the quantity of fuel pumped from the plunger; is controllable after the variable discharge stroke of the plunger, and furthermore the second depressurization passage 2
8 is connectable via a second outlet opening 29 in the plunger with an annular groove 30 provided in the cylinder 2, via which the second outlet opening is connected to one of the limiting edges of the annular groove. The second depressurization channel 28 can also be controlled at the end of the discharge stroke of the plunger by the ring slide 17 via the third outlet opening 32. In one version, the control edge of the annular slide 17 is provided with recesses 34 distributed in accordance with the selection of the delivery stroke of the plunger, which prevent fuel pumping at least partially. The recess is assigned to the respective position of the third outlet opening 32 and only to the third outlet opening during the discharge stroke of the plunger; 1. A fuel injection pump for an internal combustion engine, characterized in that the outlet opening 16 of the fuel injection pump is controlled to open early. 2. The second outlet opening 29 is connected to the pump working chamber 5 via an annular groove 30 at the beginning of the respective delivery stroke of the plunger and after the pump delivery stroke corresponding to a fuel injection quantity greater than twice the idling injection quantity. 2. A fuel injection pump for an internal combustion engine according to claim 1, wherein the connection between the pump working chamber 5 and the second outlet opening 29 is interrupted via a limiting edge of the annular groove. 3. Injection pump for an internal combustion engine according to claim 2, wherein the first outlet opening 16 and the third outlet opening 32 are located in a common plane perpendicular to the plunger axis. 4. A fuel injection pump according to claim 2, wherein the third outlet opening 32 and/or the first outlet opening 16 are controlled by the upper end face of the ring slider 17 towards the end point of the discharge stroke of the plunger. . 5. The third outlet opening 32 and/or the first outlet opening 16 are controlled by a limiting edge of an inner ring groove 39 located on the inner circumferential surface of the ring slide 17'. Fuel injection pump for internal combustion engines. 6. The circumferential surface of the plunger is provided with filling longitudinal grooves 7, which are always connected to the pump working chamber 5 and cooperate with suction holes 18 distributed correspondingly on the circumferential wall of the cylinder. In addition, the vertical filling groove 17 is connected to the annular groove 37, through which the suction hole is opened during the determined pre-stroke _hv by the lower limit edge of the transverse groove. 6. A fuel injection pump for an internal combustion engine according to claim 1, wherein the plunger 8 remains connected to the filling longitudinal groove 7 after the start of the discharge stroke of the plunger.