JPH0311150A - Fuel injection pump for internal combustion engine - Google Patents

Abstract

PURPOSE: To set a control edge for mechanical regulation used in an abnormal operation to not disturb a regulatable range of an electrical regulation by using individual injection pump rotating position for the electrical regulation and the mechanical regulation. CONSTITUTION: In an injection pump 1, a piston 3 is slid in a cylinder 2 arranged in a pump casing 4, a control hole 6 is connected to a suction chamber 5 through a hole 7, and an injection rate and an injection time point are electrically controlled by a solenoid valve 9 connected to a work chamber 8. In the case where the solenoid valve 9 is failed, the piston 3 is rotated on a rotating position where control edges 15 to 17 are operated together with additional control holes 20, 21 for an abnormal operation through a regulating member 18 operated together with a regulating rod 13, and injection operation is mechanically regulated. The control edge for mechanical regulation which is used only at the time of the abnormal operation is rotated to a position which is not effective for the electrically regulation, and a range capable of regulating through the electronic regulation is not prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The invention relates to an injection pump for an internal combustion engine, which comprises a pump piston which is oscillably driveable in a pump cylinder and which cooperates with a control lip of the pump piston. at least one control hole for controlling the connection of the pump piston to the working chamber;
controllable valves.

Prior Art An injection pump of the type mentioned at the beginning is, for example, DE-AI36.
32 299. In this known fuel injection pump, the pump piston has an inclined edge and a further control edge on its cylindrical vibrating surface, so that at least one hole in the piston is rubbed by this control edge. In such a configuration of the inclined edge control device, the discharge is terminated depending on the rotational position of the piston or the inclined control edge. This is because when a suitable outlet hole is opened with an inclined control edge, fuel flows out of the pressure chamber of the injection pump into the outlet line. The start of the discharge stroke is usually defined by the upper edge of the piston, and the compression stroke begins when the upper edge of the pump piston scrapes the hole through which the fuel exits into the suction chamber.

An electronic regulating device is additionally provided as disclosed in DE-053632299 for controlling a solenoid valve, which is connected to a separate outflow as disclosed in DE-053632299. If it is built into the hole,
With such a solenoid valve, adjustment is performed only within the range where fuel can flow out to the outflow hole.Therefore, solenoid valve control is performed after normal fuel amount control by rotation of the piston, so that the fuel reaches the appropriate outflow hole. In order to be able to guarantee proper fuel quantity control and adjustment of the injection point with such solenoid valves, which are only effective in the range, the control edge of the piston must be It must be configured to provide maximum early injection.

If the control edge of the piston is configured in this way, an earliest injection point is provided for which a correct mechanical adjustment is never possible if, for example, the solenoid valve does not work in the closed position due to locking. It becomes like this.

Therefore, in emergency operation, i.e. in operation in which the solenoid valve remains closed and the adjustment is carried out mechanically via the adjusting rod by rotation of the piston, unfavorable preconditions are provided for mechanical adjustment. .

The object of the invention is to improve an injection pump of the type mentioned at the outset so that, in the absence of electronic regulation, it is possible to rely on qualitatively normal mechanical regulation only. The objective is to ensure that mechanical adjustments are made that can be compared with adjustments. In other words, the object of the invention is to provide an injection pump in which both electronic and mechanical adjustment can be carried out under the best possible conditions.

The object of the invention is to provide an injection pump of the type mentioned at the outset, in which the pump piston is in a second rotational position different from the rotational position in which the control lip of the pump piston cooperates with the control hole. has an additional cutout or hole in the piston, which cutout or hole alternates during the entire working stroke of the piston to provide an open connection from the working chamber of the pump screw in the pump cylinder to one of the control holes. The solution is that the controllable valve is connected to the supply conduit to the control hole.

Effects of the invention Due to the use of separate pump rotational positions for electronic and mechanical adjustment, the control edge for mechanical adjustment is only used in emergency operation.
During electronic adjustment, which is a normal operating condition, it is rotated to a rotational position that is no longer valid for electronic adjustment and thus no longer interferes with the range of adjustment possible via electronic adjustment.

On the other hand, after the piston has been rotated into a position in which the control edge engages the circumferential surface of the piston in the mechanical adjustment in case of emergency operation, this configuration of the control edge meets the requirements for proper mechanical adjustment. can be considered. In this case there is no possibility of electronic adjustment using solenoid valves. This is because electronic adjustment is not performed by rotating an adjustment rod and piston, as is the case with mechanical adjustment.

According to one embodiment of the invention, the controllable valve is configured to be spring-loaded in the open position. In such a configuration, the solenoid valve can be placed in a single intake and communication hole common to mechanical and electronic regulation. In this case, in the case of mechanical adjustment, after the piston has been rotated with the electronic adjustment switched off to a position where the control lip cooperates with the suction and communication holes, the valve is moved into the open position by spring force. is maintained.

Switching from electronic to mechanical adjustment during emergency operation can be carried out, for example, by means of a rotary drive device, which uses the adjustment rod itself to rotate the piston into the position set for the mechanical adjustment. can. In the case of electronic adjustment, in which the control edge of the piston does not cooperate with the suction and communication holes, on the contrary, the usual method for rotating the pump piston in order to achieve different injection quantities or different injection times is possible. It is advantageous to switch off the drive. In this case, the rotation of the piston is not necessary because the reduction control is performed by the operation of the solenoid valve. In this case, it is advantageous for the configuration to be such that the rotational position is locked at the position where the electronic adjustment is desired to be effective. In this case, the pump piston can be locked in the second rotational position.

In the second pivot position, in which the electronic mode of operation takes place and the pump piston is advantageously lockable, a solenoid valve is arranged throughout the entire stroke of the pump piston which is important for the injection process. Open connections to the suction and communication holes provided shall be made. In this case, it is advantageous if the piston recess in the second pivot position of the pump piston is constituted by a groove extending in the piston's circumference in the longitudinal direction of the piston.

Reliable emergency operating characteristics with mechanical adjustment are possible in this configuration, as already mentioned, if only one common suction and communication hole is provided for both operating states, electronic adjustment is possible. It goes without saying that this is only guaranteed if the valve is reliably brought to the open position when the valve is missing. Once the valve is locked in the closed position, mechanical adjustment is no longer effective. In order to guarantee a reliable and correct mechanical adjustment with the normal bevel control in emergency operation, independent of the position in which the solenoid valve is no longer activated, the control hole controlled by the controllable valve must also be It is advantageous to provide a further control hole in the pump cylinder. This control bore cooperates with the control lip only in the first pivot position H of the pump piston. Furthermore, in all pivoted positions of the pump piston, the control bore that cooperates with the control lip or the additional recess or bore in the other pivoted positions is tightly closed by the pump piston. Additional control holes are provided for mechanical emergency operation, in particular at least one suction and communication hole, so that the tiat valve is arranged in a pivoted position in which the mechanical adjustment becomes effective. Under the precondition that the suction and communication holes are tightly closed, a reliable adjustment is achieved via the suction and communication holes only by mechanical adjustment, even when the solenoid valve is extended into the closed position. In this case, it is advantageous if at least two separate additional control holes are provided for allowing fuel to flow out or into the working chamber.

In this case, the control hole for the inflow is arranged at a greater axial distance from the end face of the pump cylinder, which limits the working chamber, than the at least one control hole for the outflow of fuel from the working chamber. Such an additional control hole ensures that even in the pivoted position of the piston, the intake and communication holes for the solenoid valve are already rubbed by the upper edge of the piston for mechanical adjustment. In this case, a further control hole through which the fuel flows out is arranged at the same axial distance from the end face of the working chamber as the control hole which can be controlled via the valve;
It is advantageous if it is ensured that the influence of suction and communication holes on the solenoid valve, which may still co-operate with the upper edge of the pump piston, is reliably excluded. In particular, the above-mentioned arrangement allows an arrangement in which the intake and communication holes to the solenoid valve remain covered or tightly rubbed together during the entire piston stroke in the event of a mechanical emergency operation.

Embodiment In the injection pump 1 shown in FIG.
is driven to vibrate.

The piston bush or pump cylinder 2 is arranged in a sealed manner in a pump housing 4 and is at least partially surrounded by a suction chamber 5 under pre-pump pressure. The piston bushing 2 also has a control hole 6, which is connected to the suction chamber via at least one further hole 7, which is shown schematically. A solenoid valve 9 is connected from the suction chamber 5 to the working chamber 8 of the pump piston 3, via which the delivery quantity and the injection time can be adjusted with complete electronic control.

A conduit 10 leads in a known manner from the working chamber or high-pressure chamber 8 via a valve 11 to an injection nozzle 12, which is only shown schematically. Fuel is injected through the injection nozzle 12 after a predetermined pressure has been established in the high pressure chamber. The drive of the pump piston takes place via a camshaft, which is also not shown in detail, in a known manner. The camshaft engages the piston at its end opposite the working chamber 8.

In order to adjust the rotational position of the pump piston 3, a schematically illustrated adjusting rod 13 is provided, with which the pump piston is rotated in a known manner, not shown in detail. In a fully electronic control during normal operation of the injection process, in which the control of the solenoid valve 9 takes place in a schematically illustrated control unit 14, the pump piston 3 is moved in a predetermined rotational position via an adjusting rod 13, e.g. 3 and 4 between the working chamber or high pressure chamber 8 and the control hole 6 in any stroke position of the piston 3, as shown in more detail in FIGS. 3 and 4. Tagged to obtain an open connection. In this case, the injection process is regulated only by actuating the solenoid valve 9. This solenoid valve 9 is integrated into the control line 6 in such a way that it is spring-loaded in the open position. In the case of electronic adjustment, the control edge 15 implied in FIG.
．． 1617 are in a rotational position where they do not cooperate with the control holes.

In the event of a failure of the electronic control unit or a failure of the solenoid valve 9, the pump piston can be activated in a known manner by means of a control lip for emergency operation via an adjustment element 18 cooperating with an adjustment rod 13. Rotated into a mechanically adjustable rotation position.

In the situation shown in FIG. 1, the control hole 6 therefore cooperates with the control hole 6 via the circumferential control lip of the pump piston from the illustrated pivoted position in which the control hole 6 connects with the longitudinally extending groove 19 of the piston. The piston can be rotated to a position that can be mechanically adjusted. In this case, however, the connection between the suction chamber 5 and the working chamber 8 of the piston is always kept open even in the event of a failure of the valve 9, so that fuel can flow in and emergency operation is guaranteed through mechanical adjustment. It must be possible to do so.

However, as already mentioned, it is also conceivable that the valve 9 will be locked in the closed position even if an attempt is made to load the valve 9 into the open position. In this case, the connection between the suction chamber 5 and the working chamber 8 is interrupted, so that fuel transport is no longer possible. In order to ensure proper emergency operation by mechanical adjustment of the injection process even in such cases, the first
As shown in the figure, further control holes 20 and 21 are arranged in the piston bushing 2 and are in open connection with the suction chamber 5. In this case, in the case of complete electronic adjustment via the control hole 6, the aforementioned additional control holes 20 and 21 are fitted more closely to the piston 3, as will be explained further in detail in connection with the following figures. be rubbed by.

Only after electronic adjustment is no longer possible can the piston 3 be moved via the adjusting rod 13 so that the control edge is connected to the additional control holes 20 and 21.
is moved into a rotational position in cooperation with. In contrast, the control bore 6 is rubbed tightly by the piston. Therefore valve 9
Fuel delivery is guaranteed regardless of the position of the control hole 20.
and 21, so that the proper mechanical adjustment is not influenced via the control hole 6 even when the valve is in the open position.

In FIG. 2, a partial sectional view of the piston face unit 2 is shown. The drawing shows the working chamber of the pump piston 3 and the control hole which is controlled via a solenoid valve, not shown, as well as an additional control hole 20 arranged in pairs in this case.
and an additional control hole 21 axially spaced from this. The pump piston furthermore shows a control groove 19 extending in the longitudinal direction of the pump piston. In the t: position shown in FIG. 2, therefore, the injection process is regulated via the solenoid valve. Additional control holes 20
and the control hole 21, which is not shown in detail, are rubbed tightly by the pump piston 3 in this rotational position.

In FIG. 3, the piston 3 is unfolded and the control hole 6 cooperates with a control groove 19 extending in the longitudinal direction of the piston, which provides an open connection between the control hole 6 and the working chamber 8 in any stroke position of the piston. shown in the rotated position. In this rotational position the additional control holes 20 and 21 are rubbed by the piston. In the absence of electronic adjustment, the piston is rotated in the direction of arrow 22 in the embodiment shown in FIG. In addition, in connection with the mechanical adjustment of the piston, the control edges 16 and 17 have additional control holes 2.
He begins to collaborate with 021. In this case, the two end positions of the additional control holes for the control edges 16 and 17 in the mechanical adjustment are designated by the symbols 20' and 20'' or 21' and 21''. In this case, the control edge 17 cooperates with an additional control hole 21 to control the start of delivery, and the control edge opens the additional control hole 20 again in the next step, in this case in the longitudinal direction of the piston. The reduction control takes place via a connection with the working chamber, which is made in a groove 19 extending into.

As can be seen in FIG. 3, the control edges are configured in pairs for cooperation with additional holes 20 and 21 provided in pairs. In the configuration shown in FIG. 3, when adjusting the piston 3 in the direction of arrow 22 when transitioning from electronic adjustment in normal operation to mechanical adjustment in emergency operation,
A transition is made through the minimum injection quantity as indicated by the position of the control edge relative to the additional control holes in positions 20' and 21'.

In FIG. 4, a modified embodiment of the control piston 3 is shown. In this embodiment, the longitudinal groove 19 and the control hole 6
From the electronic control shown in FIG. 4 in conjunction with the control, a transition takes place via the maximum injection quantity to a mechanical adjustment by rotating the piston in the direction of the arrow 23. Control edge 16.1, which also occurs due to mechanical adjustment in this case
The end positions of the additional control holes for 7 are marked 20' and 2.
0'' or 21' and 21''. For mechanical adjustment, the additional control hole 6 is rubbed tightly by the pump piston.

If only the control hole 6 is provided, as described in connection with FIG. 1, a pump piston configuration similar to that of FIG. 4 can be used. In this case there are no differences for the electronic control. For mechanical emergency operation with the known control edge adjustment, the piston must in such a case be rotated in the opposite direction to the direction of arrow 23. In this case, the start of delivery must therefore be provided by the cooperation of the edge 15 of the pump piston 3 with the control hole 6, and the end of delivery by the inclined control edge. In a structure with only one control hole 6, the pump piston 3 can have a control edge with a simple structure.

The pump piston is constructed in such a way that an open connection is obtained from the working chamber 8 of the pump piston 3 to the control bore 6 during the entire working stroke of the piston during electronic adjustment, so that mechanical emergency In the case of operation, the arrangement of the control edges is such that the mechanical adjustment also ensures that the operation is carried out properly as a whole. Furthermore, if additional control holes are provided in the rotational position of the pump piston for electronic or mechanical adjustment, each other control hole is rubbed tightly by the pump piston, so that the injection process is not activated. Influenced by a control hole that is not in condition is avoided.For this purpose, the feed hole 21, which together with the control edge 17 determines the start of the discharge upon mechanical adjustment, has a greater distance from the end face 24 that limits the working chamber 8. It is located at
The control hole 21 for draining the fuel is arranged at least the same distance from the end face of the working chamber as the control hole 6 controlled by the valve 9. In order to further prevent influences through the control holes which are desired to operate in other modes of operation, the arrangement of the control holes as a whole is such that even during the suction stroke of the pump piston 3 the control hole or outlet 20 is located at the lowest point of the piston. In both positions, the restriction formed by the upper edge of the piston does not allow it to open, but remains tightly closed.

By connecting the Ti, Fii valve 9 directly to the connecting conduit between the suction chamber 5 and the working chamber or high pressure chamber 8,
The overall structure becomes simpler. Because electromagnetic valve 9
This is because the bushing can be directly connected to the piston bundling 2 by a single screw, and the bushing can be attached later.

In this case, the piston bushing 2 can be arranged directly on the pump housing 4, so that even if cracks should occur in the bushing, the entire pump remains tightly sealed to the outside.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a sectional view of the injection pump of the present invention, and FIG. 2 is a cross-sectional view of the bushing and pump piston shown in FIG. 1, taken along line ■-■ in FIG. 3 is a developed view of the end area of the pump piston that cooperates with the control hole, and 1g4 is a sectional view of the second embodiment of the pump screw.
This is a diagram corresponding to FIG. 3. l... Injection pump, 2... Viston bunyu, 3 Pump piston, 4... Pump caning, 5 Suction chamber, 6
...Control hole, 7...Connection hole, 8...Working chamber 9...
- Solenoid valve, 10... Conduit, 11... Valve, 12... Injection nozzle, 13... Adjustment rod, 14... Control unit, 15, 16. 17... Control edge, 18... - Adjustment member, 19... Vertical groove, 20.21... Additional control hole 2
2.23... Adjustment device for emergency operation, 24... End face. -1------Be3 19 20' 0 9 23

Claims (1)

[Claims] 1. An injection pump for an internal combustion engine, with a pump piston that can be driven oscillably in a pump cylinder and a connection of the pump piston to a working chamber in cooperation with a control lip of the pump piston. In the version with at least one control hole for controlling the control hole and a controllable valve, the pump piston has a control edge (15, 16, 17) of the pump piston (3).
an additional notch or hole (19) in a second pivot position different from the pivot position in which the
), the cutout or hole (19) being open from the working chamber (8) of the pump piston in the pump cylinder (2) to one of the control holes (6) over the entire working stroke of the piston. Fuel injection pump for an internal combustion engine, characterized in that the controllable valve (9) is connected to the supply conduit to the control hole. 2. Injection pump according to claim 1, characterized in that the controllable valve (9) is configured to be spring-loaded in the open position. 3. Injection pump according to claim 1 or 2, wherein the pump piston (3) is lockable in the second rotational position. 4. The notch of the pump piston (3) provided at the second rotational position of the pump piston (3)
4. Injection pump according to claim 1, wherein the injection pump is constituted by a longitudinally extending groove (19). 5. Besides the control hole (6) controlled by a controllable valve, at least one further control hole (20, 21) is provided in the pump cylinder (2), said control hole (20, 21
) is adapted to cooperate with the control lip only in the first rotational position of the pump piston (3), and in any rotational position of the pump piston (3) the control lip (15, 16
, 17) or in each other rotational position, the additional recess or hole (19) is tightly closed by the pump piston (3). 6. At least two further additional control holes (20, 21) are provided for the inflow or outflow of fuel into or out of the working chamber (8), a control hole for inflow; (21) is arranged at a greater distance from the end face (24) delimiting the working chamber of the pump cylinder than the at least one control hole (20) for draining fuel from the working chamber (8). Injection pump as described. 7. At least one control hole (20) for draining fuel
is controlled via a controllable valve (9).
7. Injection pump according to claim 5, wherein the injection pump is arranged at least the same axial distance from the end face (24) of the working chamber (8).