JPH0223709B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The industrial field of application of the present invention is a fuel injection method and a fuel injection device for internal combustion engines.

That is, the present invention reduces at least the amount of injected fuel to
At the regulated fuel supply pressure, the delivery stroke is started by means of a controllable supply cross section of the supply valve inserted in the supply line from the conveying pump to the pump working chamber of the injection pump configured as a plunger pump. A method for injecting fuel into an internal combustion engine, in which the amount of fuel is previously metered and stored in a pump working chamber, and the fuel injection ends when control of the return of fuel from the pump working chamber is started, and for carrying out this method. A fuel injection system, wherein the fuel injection pump is provided with an adjustment device for modifying the end of the effective delivery stroke of the pump plunger, the adjustment device controlling the emission control hole and the emission control hole. The present invention relates to a fuel injection device for an internal combustion engine of the type in which the relative position between the control surface and the control surface that closes during the effective delivery stroke can be varied and is further provided with a pressure regulating valve for regulating the fuel supply pressure.

A prior art fuel injection pump of this type is described in German patent application no. This is regulated by a variable supply cross section of the constructed supply valve. The sloping control edge that limits the effective delivery stroke is only adjusted for fuel increase control during start-up. In this known fuel injection pump, the start of thrust is necessarily changed when the delivery amount changes, but this modification of the start of thrust is done by inserting it into the camshaft drive and This is done through an expensive injection timing machine that transmits the torque.

Therefore, the problem to be solved by the present invention is to provide a fuel injection method and a fuel injection method that can change the start of thrust in relation to engine operating values while accurately metering without using a member that transmits drive torque. An object of the present invention is to provide an injection device.

As a means for solving this problem, in the fuel injection method of the present invention, as described in claim 1, in the above-mentioned type of fuel injection method, the amount of fuel stored in the pump working chamber is reduced. During the metering period, in addition to the fuel supply pressure, the supply cross section is also kept constant, and only the opening period of the supply valve is electrically controlled, and when the amount of injected fuel remains unchanged,
By varying the amount of return fuel that is fed back into the pump working chamber before the start of thrust, the desire for the start of thrust can be adjusted in relation to the engine operating value and when changing the fuel injection quantity. In order to avoid unavoidable deviations, the returned fuel amount is simultaneously corrected in relation to the metered fuel amount.
Further, in the fuel injection device according to the present invention, as described in claim 9, in the fuel injection device of the above-mentioned type, the supply valve is configured to control the fuel stored in the pump working chamber by the opening period of the supply valve. The adjusting device is configured as a magnetic valve for determining the quantity, and furthermore, the adjusting device can be actuated by an electromechanical adjusting element, which adjusting element is configured to control the at least one internal combustion engine in order to shift and correct the start of stroke. It can be controlled by control pulses of an electrical control device that is associated with the operating value and is connected to a setpoint value signal generator and a setting distance signal generator of the regulating device, and which controls the magnetic valve. A metering pulse was provided to determine the opening period.

In short, with the method of the present invention, it is not necessary to use an expensive correction mechanism that transmits a drive torque to correct the thrust start, and moreover, the metering of the amount of injected fuel maintains the fuel supply pressure and supply cross section constantly. This is done by electrically controlling only the opening period of the supply valve under the condition that the fuel injection amount is unchanged, and by controlling the amount in relation to the engine operating value when the fuel injection amount is unchanged, or by adjusting the adjustment when the fuel injection amount is changed. Since the tilt control edge is rotated in dependence on the amount of fuel injected, the metering of the fuel injection amount is achieved with great precision.
Furthermore, in the device according to the invention, an expensive correction mechanism for transmitting a drive torque is not used for the correction of the start of thrusting, and an electric machine for operating the opening period of the magnetic valve that determines the amount of fuel injection as well as the adjustment device is used. By being able to control the regulating elements with great precision and by precisely coordinating the control pulses and the metering pulses with each other, the metering of the fuel injection quantity is carried out with great precision and the quantity of fuel injected is This makes it possible to compensate for mutual interference between the thrust and the beginning of thrusting.

Claims 2 to 8 describe advantageous embodiments of the method according to claim 1. For example, as stated in claim 2, when the returned fuel amount is sucked in again in the first part of the suction stroke, if only the injected fuel amount is measured by the opening period of the supply valve. , the amount of fuel injected can be metered precisely by means of the supply valve alone. In the embodiment according to claim 3, throttling losses that occur during the emission control and re-intake of the recycled fuel quantity are avoided, especially at high rotational speeds. In the embodiment of claim 4, metering is always carried out with the feed hole fully open, and according to claim 5 metering is not influenced by pressure oscillations. . During the stop period of the pump plunger,
This is because significantly more uniform pressure conditions are created than if metering were to take place during the plunger stroke movement. By controlling the pump plunger movement and the opening period of the supply valve as claimed in claim 6, the injection quantity is determined simply by the timing of opening of the supply valve.

In the method according to claims 1 to 6, the metering is performed by means of a supply valve in the pump working chamber, which is brought to a negative pressure that corresponds at least approximately to the fuel vapor pressure during the suction stroke of the pump plunger. Therefore, if the supply pressure is chosen relatively high, for example 50 bar, the fuel vapor pressure as a back pressure will be reduced by the The pressure value is so low that it can be regarded as a constant pressure value. However, as in claim 7,
It is also possible to modify the supply pressure or preferably the opening period of the supply valve as a function of the temperature. Such a modification is possible if the supply pressure is not very high, e.g. 5 bar, so that the diesel fuel vapor pressure is e.g. 20 for 0.05 bar at 100°C.
This is advantageous in cases where differences of the order of 0.001 bar in °C have a clear influence on the metering.

In the embodiment of claim 12, due to the pressure difference between the magnet valve and the supply hole, the line volume behind the magnet valve no longer has an adverse effect on the metering as a harmful dead space volume. . With the suction passage device according to claim 13, a pressure balance is created in the supply line during the effective delivery stroke, and at the same time it is also possible to eliminate harmful injected fuel leaking along the pump plunger. No reaction is exerted on the magnet valve.

According to the constituent elements of the entirety of claim 14, it is possible to avoid the throttling effect occurring when re-inhaling the returned fuel quantity, and in the embodiments of claims 15 and 16, The temperature influence on the fuel vapor pressure in the pump working chamber as a back pressure of the supply pressure is taken into account by corresponding modification of the supply pressure,
According to the structure of Claims 17 to 21, an undesired change in the fuel amount that occurs when the thrust start timing is shifted to the engine speed is prevented or corrected to a predetermined value.

In the following, the configuration of the present invention will be specifically explained with reference to embodiments shown in the drawings.

In the fuel injection device shown as a first embodiment in FIG. 1, reference numeral 10 designates a mechanically driven pump nozzle, which essentially
Drive cam 11 of drive device 11 not shown in detail
It consists of an injection pump 12 driven by a, and an injection nozzle 14 combined with this injection pump 12 in a common casing 13. The casing 13 is only shown schematically in dashed lines to simplify the drawing.

A pump plunger, designated by 15, is axially movable and rotatably guided in the barrel 16 and delimits a pump working chamber 18 with its end face 17 facing away from the drive 11; End face 17
a horizontal first control edge 19 formed by
and an inclined second control edge 22 formed by a cutout that axially partitions the control surface 21 , by means of which a second control edge 22 is formed in the wall of the barrel 16 . The exhaust control hole 23 is opened at the end of the effective delivery stroke and is closed again after the first part of the suction stroke, which allows the re-intake of the recycled fuel quantity.

In order to correct or adjust the effective delivery stroke of the pump plunger 15, the injection pump 12 is equipped with an adjusting device 2.
4, of a known type, with a longitudinally movable adjusting rod 25 and a pinion sleeve 26.
It consists of. Both parts 25, 26 of the adjustment device 24 are provided with teeth, so that a longitudinal movement of the adjustment rod 25 by means of the adjustment member 27 causes
A pinion sleeve 26 rotates the pump plunger 15 and opens the discharge control hole 23 and the inclined control lip 2.
2, and the relative position between the discharge control hole 23 and the control surface 21 that closes the discharge control hole 23 changes during the effective feeding stroke. The discharge control hole 23 has a return pipe 2.
8 is connected, and this return line 28 opens into a supply line 31 to which fuel is sent from a transfer pump 29. Fuel supply pressure in supply pipe 31
P _Z is regulated by a pressure regulating valve 32 to a constant value, preferably 50 bar. This supply pressure, which is extremely high compared to the supply pressure of known injection pumps, is also present in the return line 28, which makes it possible to ignore the throttling losses that occur during the re-intake of the return fuel quantity. The value can be kept as small as possible. Additionally, the discharge control hole 23
can be designed as a mold cavity with a partition edge parallel to the oblique control edge 22 in order to reduce throttling effects during its reclosure.
In some cases, a large number of discharge control holes 23 may be provided. The re-inhalation of the returned fuel amount can be carried out without any problem if the accumulator 33 is provided near the discharge control hole 23 as schematically shown by the chain line. If such an accumulator 33 is provided, it is possible to interrupt the connection of the return line 28 to the supply line 31 and return the fuel directly to the tank 35, as indicated by the separation line 34. You can also do it. In this case, the pressure in the return line 28 is maintained at the fuel supply pressure by the pressure maintenance valve 36.
It is possible to limit the return pressure to a value different from P _Z. This makes it possible to adjust the pressure in the supply line 31 and the pressure in the return line 28 independently of each other, so that injection takes place in each case under advantageous conditions.

A supply line 31 controlled by a supply valve 37 opens into the barrel 16 by a supply hole 38 . However, when the pump plunger 15 is in the position shown, this feed hole 38 is covered by the control surface 21 over the entire outer surface of the pump plunger 15 except for the discharge channel, so that the pump plunger 15 is in its suction stroke. Complete bottom dead center UT
The pump is connected to the pump working chamber 18 only when it reaches . The bottom dead center UT and top dead center OT of the pump plunger 15 are indicated by chain lines and have a mutual spacing corresponding to the plunger stroke h.

The supply valve 37 is designed as a magnet valve that meters the fuel quantity Q _Z stored in the pump working chamber 18 by its opening period t _V ; in the illustrated embodiment, the stored fuel quantity is injected. is equal to the fuel quantity Q _E.
The magnet valve (supply valve 37) is configured as a 2-port 2-position valve and is shown in the closed position and receives a metering pulse I _Z defining its opening period from an electrical control device 39, which control device 39 has an electronic control circuit, and the target value signal generator 4
1. It is connected to the adjustment distance signal generator 42 of the adjustment device 24 and the rotation speed signal generator 43 which emits the rotation speed signal n. In addition, electrical control device 39
Furthermore, signals related to engine operating values, e.g.
It receives a temperature signal T taken from a suitable location and a further signal S representing, for example, the charge air pressure in the intake pipe of the engine, the exhaust gas temperature or the exhaust back pressure.

The adjusting member 27 for operating the adjusting rod 25 is formed as an electromechanical adjusting member by an electromagnetic/electrical adjusting motor or an electrohydraulic adjusting member depending on the required adjusting force, and is configured to control the load Q. or its control pulse I _FB associated with at least one operating value, such as the rotational speed n, or the correction pulse I _K as described below.
is received from the electrical control device 39. However, in this case, the change in the pivoting position of the inclined control edge 22 and thus the end of thrust produced by the regulating device 24 does not determine the fuel injection quantity Q _E , but according to the invention serves to vary the timing of the onset of thrust. . In this regard, the method of the invention will be described below with reference to FIG.

The metering of the fuel controlled by the magnet valve takes place via a constant supply cross section A _Z with a constant fuel supply pressure P _Z and by varying the opening period of the magnet valve by means of a metering pulse I _Z. . Constant supply cross section A _Z is supply hole 38
or by the flow cross section of the magnet valve (supply valve 37). The flow cross-section of the magnet valve (supply valve 37) is represented by a through channel with a flow restriction of the switching symbol of the magnet valve. The fuel supply pressure P _Z acts against the fuel vapor pressure present in the pump working chamber 18 at the end of the suction stroke, which fuel vapor pressure is at 20°C.
0.001 bar, 0.05 bar at 100 °C, and if the supply pressure is very high, for example 50 bar, it is not necessary to measure it exactly and it can be taken as an absolute vacuum of 0 bar for determining the metering pulse I _Z. can. If it is nevertheless desired to take the operating temperature of the injection pump into account, this can be taken into account in the determination of the metering pulse I _Z by means of the temperature signal T in the electric control device 39. Alternatively, the supply pressure P _Z can also be modified by varying the initial spring force of the pressure regulating spring 45 of the pressure regulating valve 32 by means of an regulating member 44 controlled by the electrical control device 39. .

Supply pressures that are novel and inventive in themselves
As a means of adapting _P
7, the conveying pump 2 is driven in parallel with the injection pump 12 or simultaneously with the conveying pump 29.
It can also be connected to the working chamber 48 of an auxiliary pump 49 supplied with fuel from 9. In this case, the suction pipe 47 has a check valve 5 which opens towards the working chamber 48.
1 and can be adjusted in such a way that its working chamber 48 is correspondingly partially filled in order to create a negative pressure corresponding to the fuel vapor pressure occurring with each suction stroke of the injection pump 12. . This adjustment is
Pump plunger 50 with inclined end face
This is done by rotating the . Such an auxiliary pump 49, which is formed by a plunger pump, is relatively expensive and is therefore used when very precise metering is desired. For this purpose, the auxiliary pump 49 is only an alternative, and its connecting lines are shown in broken lines.

The pump working chamber 18, which faces the injection nozzle 14 and is closed off by the delivery valve 52, is made as small as possible in order to avoid creating harmful interstitial volumes. Furthermore, in order to ensure that the same pressure conditions always occur in the feed hole 38 each time a metering takes place, the pump plunger 15 closes the feed hole 38 to the pump work chamber 18 during the effective delivery stroke. The outer surface part is a suction passage device 53
It is equipped with Federal Republic of Germany Patent Application Publication No.
This suction passage device 53, which can be constructed as a passage device consisting of a longitudinal groove and a transverse groove as described in 2720279, is furthermore connected to a suction ring groove 54 and is thus It also serves as a passageway for recovering oil leaks. By means of this suction passage device 53 the supply hole 38 is maintained at a constant pressure, preferably at a supply pressure _P
, which in the illustrated embodiment is connected to a partial ring groove 5 in the inner wall of the barrel 16 .
5. This partial ring groove 55 is of a type not shown in the drawings,
It is connected to the part that is under continuous fuel supply pressure _PZ , that is to say the part of the supply line between the conveying pump 29 and the magnet valve (supply valve 37).

The second embodiment, which is only partially shown in FIG. 2, differs only slightly from the first embodiment shown in FIG. Therefore, the same parts are given the same reference numerals, and the different parts are given the numbers with a dash.

The feed hole 38', which is cut off by the pump plunger 15 to the pump work chamber 18 during the effective delivery stroke, is designed as a throttle hole which forms a constant feed cross section _AZ . The flow cross section of this throttle hole (feed hole 38') must therefore be smaller than the flow cross section of the magnet valve (feed valve 37'), and also the flow cross section of the magnet valve and the feed hole of the supply line 31. 38' should be smaller than the flow cross-section of the line section 31a between it and 38'. By arranging the feed hole 38', which is designed as a throttle hole, it is ensured that there is always the same amount of water in the line section 31a before and after the end of the metering carried out by the magnet valve (feed valve 37'). A pressure condition may exist. This is particularly true if the end of storage is controlled by the pump plunger 15 itself, in other words, in order to determine the opening period t _V of the supply valve 37', the valve opening time t _O ¨ is simply varied. In this case, the valve closing timing t _S is determined at a time after the end of storage controlled by the valve plunger 15 . This point will be discussed in detail later in connection with FIG.

A third embodiment, only partially shown in FIG.
is shown with a magnetic valve (supply valve 37'') controlling the metering of fuel from the supply line 31 via the supply hole 38 into the pump working chamber 18. As in the embodiments already described, the pump plunger 15 is control surface 21
an inclined control edge 22 configured as an axial separating edge;
Ejection control hole 23 formed in the wall of barrel 16
is opened at the end of the effective delivery stroke, thereby metering the amount of return fuel which in the present invention influences the start-up timing. However, in this case, unlike the embodiments already described, the discharge control hole 2
3 can be closed by a valve 57 which prevents re-intake of the returned fuel into the pump working chamber 18. Although valve 57 is shown in FIG. 3 as a simple check valve, a spool-type control valve could be used instead, as is commonly done in dispensing injection pumps. In this case, the discharged return fuel passes through the return line 28 and immediately afterward, or via the pressure maintenance valve 3 which creates a back pressure.
6 and returns to the tank 35 again.

The pump element, which is only partially illustrated in FIG. The injection pump 12'' can be combined with the associated injection nozzle to form a pump nozzle.

In the injection pump 12'' described above, the magnet valve (supply valve 37'') is configured as a needle valve that controls the supply hole 38, works as a 2-port 2-position valve, and operates as a supply pressure P in the supply pipe line 31. Pressure balanced against _Z. In this case, the feed hole 38 is arranged in such a way that it is permanently connected to the pump working chamber 18 , but if desired due to the pressure conditions, the feed hole 38 can be located downwardly so that the pump plunger 15 It can also be provided that it is closed by its end face 17 during the delivery stroke. The feed hole 38 is also located further downwards (indicated by 38''), and by means of an annular groove 58 below the pump plunger 15, it is also preferably located at an intermediate position between bottom dead center and top dead center. It is also possible for the pump plunger 15 to be controlled only near the bottom dead center indicated by .

The diagram in FIG. 4 shows the curve a representing the variation of the plunger stroke h with respect to the time _t , as well as the magnetic valve (supply valve 37, 37 _' or Horizontal bars b to e representing the open period t _V of the curve 37″) are shown. The bottom dead center of the curve a
In the section rising from UT to top dead center OT, some points representing the thrust start FB and thrust end FE are marked. In this case, the symbol FE _f represents the end of thrust to control the early thrust start, and the symbol FE _s represents the end of thrust to control the slow beginning of thrust. The position of the start of thrust FB is related to the injection quantity of stored and delivered fuel and the end of thrust adjusted for correction of the start of thrust, and this point will be discussed further in the explanation of the operation below. Supply valve opening period t _V
The bars b to e corresponding to the desired metering pulses I _Z of these valves. The symbol t _R represents the stop period of the pump plunger 15 at the bottom dead center UT, and the pump plunger 15 is closed to the supply hole 3 at E _s.
8 and reopens at E _p ¨.

5 and 6 partially show two variations of the first embodiment shown in FIG. 1, each of which has one differentiating element 61 and 62; By means of the differentiating element, an undesired change in the fuel quantity when the thrust start timing is shifted too rapidly is prevented or corrected to a predetermined value.

The electrical differential element 61 shown in FIG. 5 consists of two resistors 63 and 64 and one capacitor 65. This differentiating element 61 is inserted at the connection point between the adjustment distance signal S _S of the adjustment distance signal generator 42 and the setpoint value signal generator 41 and produces a correction signal S _K , which Via element 66, it is input to setpoint value signal generator 41 as a correction value.

If the movement of the adjusting rod 25 takes place approximately linearly proportional to the rotational speed n, the correction signal S _K produced by the differentiating element 61 can also be derived from the rotational speed n. This is indicated in FIG. 5 by n' and the dashed line. In this case, the connection to the adjustment distance signal S _S is interrupted, as indicated by the separating line.

The differential element 62 shown in FIG. 6 is an electromechanical differential element, and in this case, the movement of the adjustment rod 25 is
Via a mechanical damping member consisting of a hydraulic damper 67 and two springs 68 and 69, it is transmitted to the slip contact 71a of a potentiometer 71, which inputs a correction signal S _K to the control device 39. and corrects the metering pulse I _Z for the magnet valve (supply valve 37) in a known manner. This modification is necessary in order to prevent an undesired change in the fuel amount that would occur if the thrust start timing is shifted to the engine speed, or to reduce it to a predetermined value.

In the following, the operation of the first embodiment will be explained based on FIGS. 1 and 4.

When the pump plunger 15 continues its delivery stroke from the position shown in FIG. To,
The end of thrust FE is determined by the control edge 22.
This end of thrusting is relatively slow when the pump plunger 15 is in the illustrated rotational position, _e.g.
It will be held in This is because only a small amount of return Q _R is discharged. This return ends at top dead center OT, and this return amount Q _R
is drawn into the pump working chamber 18 again through the discharge control hole 23 at the beginning of the suction stroke, and this re-suction ends when the inclined control lip 22 closes the discharge control hole 23 . When the pump plunger 15 continues the suction stroke to the bottom dead center UT, the pump working chamber 18
The fourth
During the stop period, denoted by t _R in the diagram, when the supply hole 38 _is fully opened at t _O The injection quantity is determined by the pulse period starting with _O ¨, and if the injection quantity Q _E is small, then bar b
If the injection quantity Q _E is large, the amount is adjusted according to the bar c. Then the outage period
After t _R , the delivery stroke of the pump plunger 15 is started, first of all the hollow chamber under steam pressure of the pump working chamber 18 with a volume related to the stored injected fuel quantity and the redrawn redrawn fuel quantity. is compressed and then a thrusting FB takes place, the fuel under injection pressure opens the delivery valve 52 and the fuel reaches through the injection nozzle 14 into the working cylinder of the engine. The injection ends, as already mentioned, when the pump plunger 15 connects the discharge control hole 23 to the pump working chamber 18 by means of an inclined control lip 22 immediately after the position shown in FIG. Ending of thrusting by a change in the rotational position of the inclined control edge 22 or by an adjusting movement of the adjusting rod 25 produced by the electromechanical adjusting member 27
The control of the FE does not serve to regulate the delivery amount, as in known injection pumps, but instead determines the start-up time FB by the amount of refueled fuel that is discharged and sucked in again. Magnetic valve (supply valve 3) controlled by metering pulse I _Z of control device 39
If the opening period t _V of 7) is to be changed for the purpose of controlling another fuel injection quantity, the adjusting rod 25 is moved via the adjusting element 27 by means of the correcting pulse I _K at a correspondingly adapted adjusting speed. Then, the amount of fuel returned is corrected, and as a result, the timing of starting thrusting can be kept constant. However, if it is desired to vary the timing of thrusting without changing the injection quantity in relation to the load represented by the rotational speed or the injection quantity Q _E or in relation to other operating values, the adjusting device Pump plunger 15 by 24
Another rotational position is produced. In order to precisely adjust this pivot position, the adjustment device 24 with the electromechanical adjustment element 27 is equipped with an adjustment distance signal generator 42 which supplies an adjustment distance signal to the electrical control device 39. , which is shown only schematically in FIG. 1 and which can be mounted at any point on the adjusting device 24 and formed by a capacitive, inductive or other known distance signal generator. . However, if the timing of the start of thrusting is changed to the rate of thrust, the duration of the metering pulse I _Z can be additionally varied during a short transition time to prevent an undesired amount or to reach a predetermined value. Must be corrected. This modification is performed either purely electrically by a differentiating element 61, as shown in FIG. 5, or electromechanically by a differentiating element 62, as shown in FIG. In this case, the correction signal S _K of both variant embodiments can be changed via a subtraction element 66 as shown in FIG. It is also possible to directly input the metering pulse I Z to change the metering pulse I _Z for a short time. If the timing of the start of thrusting is to be varied in relation to the rotational speed, especially if the adjustment distance of the adjusting rod 25 is linearly proportional to the rotational speed, the correction signal S _K emitted by the differential element 61 can be rotated. It can also be extracted directly from the rotational speed signal n of the number signal generator 43 (the fifth
(See figure n′).

As already mentioned, the supply cross section A _Z can also be controlled in relation to the opening period of the magnet valve (supply valve 37), so that the amount of fuel stored can also be controlled in relation to the opening duration of the magnet valve (supply valve 37). Determined by a constant flow cross section, the supply pressure P _Z is regulated by a pressure regulating valve 32 to a constant value, which value may be
Only temperature-related changes in the steam pressure within 8 are adapted by suitable modifications controlled, for example, by an auxiliary pump 49. Valve opening timing t _O ¨ and valve closing timing of the magnet valve (supply valve 37)
If T _S is located within the rest period t _R of the pump plunger 15, the pressure conditions are influenced at least by vibrations.

As already explained in conjunction with FIG. 2, if a constant feed cross section A _Z is formed by the feed hole 38', the control of the opening period _tV of the magnet valve (feed valve 37') is 4, the pressure conditions in the line section 31a are particularly advantageously influenced. In this case, the injection amount is determined by shifting the valve opening timing t _O ¨ of the magnet valve (supply valve 37').
and the supply hole 38' is opened by the pump plunger 15.
Determined by closure in E _s . The valve closing timing of the magnet valve (supply valve 37') is in this case preferably after E _s by a constant value and no longer directly controls the injection quantity, but only the valve opening timing t _O ¨ is involved in determining the quantity. do.

If the discharge control hole 23 is closable by means of a valve 57 or a corresponding valve element, as shown in FIG _. Even when the stroke starts, the magnet valve (supply valve 37') is not sucked into the pump working chamber 18 again, and the magnet valve (supply valve 37') controls the amount of fuel injected and the start of pumping by its volume due to its opening period _tV . quantity is stored in the pump work chamber 18. This additional valve 57 is shown in FIGS.
It can also be used in the pump nozzle 10 shown, in which case again the metering pulse I _Z is correspondingly lengthened.

In order to carry out the method of the invention, it is possible to use not only the pump nozzles or injection pumps described above, but also spool-type injection pumps or distribution-type injection pumps. The idea of the invention, which is common to all cases, is that during the metering of the fuel quantity stored in the pump working chamber, which is partially underpressurized during the suction stroke, the supply cross section as well as the supply pressure are kept constant. only the opening period of the supply valve is electrically regulated; a shift in the timing of the start of thrusting controlled in relation to the operating value is caused by a change in the return fuel quantity; and the injected fuel quantity. An undesired shift in the timing of the start of thrusting when changing the amount of fuel can be avoided by simultaneously correcting the amount of fuel returned. In this case, when the returned fuel quantity is being sucked in again, only the opening period of the supply valve determines the injected fuel quantity; If this is the case, the amount of fuel injected and the amount of fuel that supplements the amount of returned fuel are metered during the opening period of the supply valve.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of the injection pump of the first embodiment, FIG. 2 is a partial sectional view of the supply hole range of the second embodiment, and FIG. 3 is a partial sectional view of the third embodiment. The sectional view, FIG. 4, is a functional diagram relating to the plunger stroke, and FIGS. 5 and 6 are partial schematic diagrams showing two modified embodiments of the first embodiment. 10... Pump nozzle, 11... Drive device, 1
1a... Drive cam, 12 and 12''... Injection pump, 13... Casing, 14... Injection nozzle,
15...Pump plunger, 16...Barrel, 1
7... End face, 18... Pump working chamber, 19... Control edge, 21... Control surface, 22... Control edge, 23...
... Discharge control hole, 24 ... Adjustment device, 25 ... Adjustment rod, 26 ... Pinion sleeve, 27 ... Adjustment member, 28 ... Return pipe, 29 ... Conveyance pump,
31... Supply pipe line, 31a... Pipe line section, 32...
...Pressure regulating valve, 33...Accumulator, 34...
... Separation line, 35 ... Tank, 36 ... Pressure maintenance valve, 37-37" ... Supply valve, 38-38" ... Supply hole, 39 ... Control device, 41 ... Target value signal generator, 42 ... Adjustment distance signal generator, 43 ... Rotation speed signal generator, 44 ... Adjustment member, 45 ... Pressure adjustment spring, 46 ... Chamber, 47 ... Suction pipe line, 4
8... Working chamber, 49... Auxiliary pump, 50... Pump plunger, 51... Check valve, 52... Delivery valve, 53... Suction return passage device, 54... Suction return ring groove, 55... ...partial ring groove, 5
7... Valve, 58... Annular groove, 61 and 62...
Differential element, 63 and 64...Resistor, 65...Capacitor, 66...Subtraction element, 67...Damper, 6
8 and 69... spring, 71... potentiometer, 71a... slip contact.

Claims (1)

Claims: 1. Inserting at least an amount of injected fuel at an regulated fuel supply pressure P _Z from the conveying pump 29 into the supply line 31 to the pump working chamber 18 of the injection pump 12 configured as a plunger pump. Due to the controllable supply cross section A _Z of the supply valve 37 , the controlled supply of fuel which is metered and stored in the pump working chamber 18 before the start of the delivery stroke and the controlled return of fuel from the pump working chamber 18 is initiated. In the fuel injection method for an internal combustion engine, which ends by pumping, during the period of metering the amount of fuel stored in the pump working chamber 18,
In addition to the fuel supply pressure _PZ , the supply cross section _AZ is also maintained constant, and only the opening period _tV of the supply valve 37 is electrically controlled, and when the amount of injected fuel remains unchanged, By changing the amount of return fuel supplied again to the pump working chamber 18, the start of thrust is shifted in relation to the engine operating value, and when the fuel injection amount is changed, an undesired shift in the start of thrust can be avoided. A fuel injection method for an internal combustion engine, characterized in that the returned fuel quantity is simultaneously corrected in relation to the metered fuel quantity in order to avoid this. 2. The method according to claim 1, wherein the returned fuel amount is sucked in again in the first part of the suction stroke of the injection pump 12 and only the injected fuel amount is metered by the opening period _tV of the supply valve 37. 3 Prevents re-inhalation of the returned fuel amount and closes the supply valve 3.
4. Opening _of the supply valves 37, 37', 37''. The valve opening timing and valve closing timing which determine the period _tV are determined by the pump plunger 1 of the supply holes 38, 38' forming the opening of the supply pipe 31 into the pump working chamber 18.
4. The method as claimed in claim 1, wherein the opening period is controlled by a corresponding control member. 5. The method according to claim 4, in which the opening period _tV of the supply valve 37 is controlled only at the end of the suction stroke. 6 The end of fuel storage in the pump working chamber 18 is controlled by the pump plunger 15, and only the valve opening timing of the supply valve 37 is changed in order to determine the opening period _tV of the supply valve 37, and the valve is closed. The method according to any one of claims 1 to 3, wherein the timing is after the storage of fuel is completed by the pump plunger 15. 7. A method according to any one of claims 1 to 6, in which the supply pressure P _Z or the opening period t _V of the supply valve 37 is modified in relation to the temperature. 8 Modifying the opening period _tV of the supply valve 37, which determines the amount of injected fuel, in the case of a quick shift of the start of thrust, during a short transition period, which also reduces the fuel amount if the start of thrust is shifted late. Correct the orientation,
8. The method according to any one of claims 1 to 7, wherein when the start of thrusting is shifted earlier, the amount of fuel is corrected to increase. 9 The fuel injection pump 12 is connected to the pump plunger 1
An adjusting device 24 is provided to correct the end timing of the effective delivery stroke of No. 5, and this adjusting device 24
Accordingly, the discharge control hole 23 and this discharge control hole 23
In a fuel injection device for an internal combustion engine of the type in which the relative position between the control surface 21 and the control surface 21 which is closed during the effective delivery stroke can be changed and is further provided with a pressure regulating valve 32 for regulating the fuel supply pressure _PZ . , the supply valves 37, 37', 37'' are designed as magnetic valves which determine, by their opening period _tV , the quantity of fuel stored in the pump work chamber 18; It can be actuated by a mechanical adjustment element 27, which in order to shift and correct the onset of thrust, is connected to an electrical control device associated with at least one internal combustion engine operating value (Q.n.S). 39 control pulses I _FB , I _K , the control device 39 includes a setpoint value signal generator 41
and an adjustment distance signal generator 42 of the adjustment device 24, characterized in that it supplies a metering pulse I _Z that determines the opening period t _V of said magnet valve 37, 37', 37''. Fuel injection device of the engine.10 The pump plunger 15, which is axially movable and rotatably guided in the barrel 16 of the injection pump 12, at least connects the feed hole 38 of the feed line 31 into the pump working chamber a first control edge 19 that closes during the effective delivery stroke and an inclined second control edge 22 axially separating said control surface 21;
By means of this second control edge 22, a discharge control hole 23 formed in the wall of the barrel 16 is opened at the end of the effective delivery stroke and the return fuel quantity is controlled at the beginning of the suction stroke. is adapted to be closed again after being re-suctioned, the magnet piece 37 in its open position directing the supply line 31 from the conveying pump 29 into the pump work chamber 18 with a constant supply cross section A _Z. It is configured as a switching valve that connects and completely blocks this connection in its closed position, and its opening period
10. The fuel injection device according to claim 9, wherein _tV determines the amount of fuel to be injected. 11. In order to determine the amount of fuel returned, the rotational position of the pump plunger 15 is variable by means of an adjusting device 24 having an adjusting rod 25, on which an electromechanical adjusting member 27 acts. 11. The fuel injection device according to claim 10, wherein one of the members moved when changing the rotational position includes an adjustment distance signal generator 42. 12 A constant feed cross section A _Z is formed by the feed hole 38' which is designed as a throttle hole, the flow cross section of the feed hole 38' being equal to the flow cross section of the feed valve 37' and the feed valve 37. ' and supply hole 3
8'. The fuel injection device according to claim 10 or 11, wherein the flow cross section of the pipe section 31a between the pipe section 8' and the pipe section 31a is smaller than the flow cross section of the pipe section 31a. 13 During the effective delivery stroke, the part of the outer peripheral surface of the pump plunger 15 that closes the supply hole 38 with respect to the pump working chamber 18 is provided with a suction passage device 53, which closes the supply hole 38 with respect to the pump working chamber 18. 12. A fuel injection device according to claim 10 or claim 11, wherein 38 is connectable to a constant pressure chamber 55. 14 The discharge control hole 23 is connected to the pump plunger 15
The pump plunger 1 is formed in the barrel wall surrounding the part with the control surface 21 of the pump plunger 1.
5 is provided with an inclined control edge 22 which axially partitions the control surface 21, by means of which the discharge control hole 23 is opened at the end of the effective delivery stroke. Furthermore, the discharge control hole 23 can be closed by a valve 57 which prevents the re-intake of the return fuel quantity into the pump working chamber 18, and the supply valve 37'' can be closed by means of its opening period _tV . The fuel injection device according to claim 9, wherein the fuel injection device is configured as a switching valve that adjusts the amount of fuel to be injected and the amount of fuel to be replenished with the amount of returned fuel.15. 15. The fuel injection device according to claim 9, further comprising an adjustment member (44) for modifying the force as a function of the operating temperature of the injection pump (12) or of the fuel. , a chamber 46 with a pressure regulating spring 45 is connected via a suction line 47 to a working chamber 48 of an auxiliary pump 49 which is driven in parallel to the injection pump 12 and is supplied with fuel by a conveying pump 29. and the suction pipe 47
The auxiliary pump 49 has a check valve 51 that opens toward the working chamber 48, and the auxiliary pump 49 has a check valve 51 that opens toward the working chamber 48. work room 4
15. A fuel injection device according to any one of claims 9 to 14, wherein the fuel injection device is adjustable such that the fuel injector 8 is partially filled. 17 The metering pulse I _Z of the supply valves 37, 37', 37'' can be temporarily corrected by the differentiating elements 61, 62 if the start of thrust is shifted quickly; Claim 9, in which the correction is made in the direction of decreasing the fuel amount when the start of thrusting is shifted earlier, and the correction is made in the direction of increasing the fuel amount when the start of thrusting is shifted earlier.
The fuel injection device described in Section 1. 18 A temporary modification of the metering pulse I _Z is generated by the differentiating elements 61 , 62 connected to the adjustment distance signal generator 42 of the adjustment device 24 and input into the control device 39 by a modification signal S 18. The fuel injection device according to claim 17, wherein the fuel injection device is made by _K. 19 Temporary modification of the metering pulse I _Z is performed by differentiating elements 61, 6 connected to the rotational speed signal generator 43.
18. A fuel injection system as claimed in claim 17, characterized in that the correction signal S _K is generated by the control device 39 and is input to the control device 39. 20. Claim 18 or 19, wherein the differential element is an electrical differential element 61, which is an RC element having at least one capacitor 65 and two resistors 63, 64. fuel injector. 21 The differential element is an electromechanical differential element 62 and at least one mechanical damper member 67
20. A fuel injection device according to claim 18, further comprising a potentiometer whose adjusting movements are damped by a potentiometer.