CN102428262B - Method for triggering an injector in an internal combustion engine - Google Patents

Abstract

In order to improve the combustion quality and in particular the accuracy of the metered fuel quantity in an internal combustion engine having a fuel injection system comprising a plurality of injectors, it is proposed that a unique activation time (74) be determined for at least one injector as a function of the lift delay (48) of the injector. The triggering operation for the injector is carried out as a function of the determined individual triggering time (74). Thus, a triggering operation unique to the injector is provided which reduces the difference in the amount of fuel dosed by the different injectors even when operating in the partial lift mode.

Description

Method for triggering an injector in an internal combustion engine

technical field

The invention relates to a method for activating injectors in a fuel injection system of an internal combustion engine, wherein the fuel injection system comprises a plurality of injectors and wherein the quantity of fuel injected by means of the injectors depends on the activation duration of the injectors time.

Furthermore, the invention relates to a control device for controlling/regulating fuel injection in an internal combustion engine, wherein the internal combustion engine comprises a fuel injection system and the fuel injection system comprises a plurality of injectors and wherein the fuel injected by means of the injectors The amount depends on the trigger duration of the injector.

Furthermore, the invention relates to a computer program which can be run on a computing device, in particular on a control unit for controlling and/or regulating fuel injection in an internal combustion engine.

Background technique

The fuel injection system can meter the fuel required for combustion in the internal combustion engine by means of one or more injectors. For gasoline direct injection and common rail injection, the fuel is injected directly into the combustion chamber. The metered fuel quantity is decisive for the combustion quality and thus for the fuel consumption and the exhaust gas properties of the internal combustion engine.

However, the amount of fuel dosed is influenced by the performance of the injector itself. Due to sample deviations that occur at the injectors used within the internal combustion engine, the fuel quantities metered by these injectors are mostly different, which subsequently leads to a reduction in the combustion quality. In particular in the so-called small range, the relative sample deviation of the injector is especially influential, since the injector is operated in partial lifting mode, ie without reaching the upper stop.

Conventional measures aimed at compensating the fuel quantity affected by the sample deviation are based on a pilot control principle which is applied uniformly to all injectors present in the internal combustion engine. For this purpose, the triggering period is calculated from the fuel quantity requested by the engine management system and—taking into account the pilot control—the triggering takes place within the internal combustion engine as a function of the fuel quantity to be dosed.

Contents of the invention

The object of the present invention is to improve the quality of combustion in an internal combustion engine and in particular to increase the accuracy of the metered fuel quantity.

This object is solved by a method for triggering injectors in a fuel injection system of an internal combustion engine, wherein the fuel injection system comprises a plurality of injectors and wherein the quantity of fuel injected by means of the injectors depends on the number of injectors Triggering duration, wherein for at least one injector, the unique triggering duration is determined as a function of the individual lift-off delay of the injector, and the triggering for the injector is determined based on the determined unique The fuel quantity deviation is determined as a function of the lift delay, and the injector-specific trigger duration is determined as a function of the fuel quantity deviation.

This object is also solved by a control device for controlling and/or regulating fuel injection in an internal combustion engine, wherein the internal combustion engine comprises a fuel injection system and the fuel injection system comprises a plurality of injectors and wherein the fuel injected by means of the injectors The amount depends on the triggering duration of the injector, wherein the control device includes a function for determining, for at least one injector in the internal combustion engine, a unique triggering duration depending on the lift delay of this injector means and includes means for triggering this injector as a function of the determined unique triggering duration, the fuel quantity deviation is determined as a function of the lift delay, and the injector-specific triggering duration The time is then determined as a function of the fuel quantity deviation. The present invention also provides other preferred technical solutions.

According to the invention, for at least one injector, an individual activation duration is ascertained as a function of the lift-off delay of this injector. The triggering operation for this injector takes place as a function of the ascertained individual triggering duration. This means that even when the injector is operated in partial lift mode, an injector-specific triggering operation is provided which reduces differences in the amount of fuel dosed by different injectors. In order to achieve this, the influence of the sample deviation of the injector is reduced.

According to the invention, not only injector-specific long-term deviations of the fuel injection quantities are compensated for, but also differences caused by tolerances.

The invention is based on the observation that, in partial lift operation, the change in needle lift and thus the injected fuel quantity is correlated with a so-called lift delay of the injector. An observation of the so-called flow activation duration characteristic curves of the individual injectors, in particular in the partial lift range, shows that the characteristic curves determined in this way are offset almost parallel to one another. The reason for this offset is a different balance of forces within the individual injectors, which originates, for example, from different closing spring forces, friction, hydraulic closing forces or magnetic forces. It has been observed that the shift of the characteristic curve is proportional to the so-called lift-off delay of the individual injectors.

According to the invention, the activation duration is therefore determined individually for each injector as a function of the boost delay, wherein the boost delay is preferably determined during operation of the internal combustion engine. This allows particularly rapid and continuous adjustments. The ramp-up delay can be ascertained here by means of different methods.

Preferably, in the control unit provided for controlling and/or regulating the fuel injection system, the averaged triggering duration is determined from a characteristic curve as a function of the predetermined fuel quantity and optionally of the pressure generated in the so-called rail. time. The average trigger duration thus determined is corrected by an injector-specific magnitude, wherein the injector-specific value is determined by the injector-specific lift delay and the storage of the lift delay in the The difference between the average values in the controller constitutes. The mean value itself then consists of the lift-off delays of a statistically significant number of injectors. The injector can be, for example, an injector present in an internal combustion engine. The influence of the ramp-up delay on the trigger duration is then taken into account by means of the amplification factor. Since the dosing of the fuel quantity by the injector is not constant with respect to the activation period, it is advantageous to use the amplification factor.

Of special significance is the realization of the invention in the form of a computer program which can run on a computing device, in particular on a control device for controlling and/or regulating fuel injection in an internal combustion engine, wherein the computer program Programming is performed for carrying out the method according to the invention. The computer program is preferably stored on an electronic or optical storage medium.

Description of drawings

Further advantages, features and details of the invention emerge from the following description, in which different exemplary embodiments of the invention are shown with reference to the drawings. The features mentioned in the claims and in the description are essential to the invention individually or in any combination. The accompanying drawings show the following:

1 is a very simplified schematic diagram of an internal combustion engine with a fuel injection system and a plurality of injectors operating according to the invention,

FIG. 2 a is a schematic detail view of an exemplary embodiment of an injector in the closed operating state,

FIG. 2 b is a schematic detail view of an exemplary embodiment of an injector in an open operating state,

FIG. 3 is a simplified schematic diagram of the stroke and needle lift profile of the injector in partial lift operation,

Figure 4 is an example of the triggering characteristic curves in the partial lift range for different injectors,

Figure 5 is a block diagram of an embodiment of the method of the present invention, and

FIG. 6 is a simplified flow diagram of an embodiment of the method according to the invention.

detailed description

FIG. 1 shows an internal combustion engine 10 which includes a fuel storage container 12 from which fuel is delivered by means of a delivery system 14 into a high-pressure fuel line 16 . The high-pressure line 16 is designed, for example, as a common rail. The high-pressure line 16 is connected to injectors 18 which are able to inject fuel directly into the combustion chambers 20 respectively assigned to the injectors 18 . The operation of internal combustion engine 10 and, in particular, the operation of a fuel injection system formed, for example, by delivery system 14 , high-pressure line 16 and injectors 18 is controlled or regulated by a control and regulating device, for example a control unit 22 . Control unit 22 can detect input values and provide output values or activate actuators, in particular injectors 18 .

FIG. 2 shows a schematic enlarged view of the injector 18 shown in FIG. 1 . The injector 18 has an electromagnetic actuator which has a solenoid coil 26 and an armature 30 interacting with the solenoid coil 26 . The armature 30 is connected to the valve needle 28 in such a way that it can move relative to the vertical direction of movement of the valve needle 28 in FIG. 2 . A valve spring 36 exerts a spring force on said valve needle 28 so that it is held in a valve seat 38 .

The injector 18 is triggered by the control device 22 , which causes the solenoid coil 26 to be energized, whereby the armature 30 moves upwards so that it engages the valve needle 28 against the spring force when it engages into the stop 32 out of the valve seat 38 of the valve needle. This situation is shown in Figure 2b. There, fuel 42 can now be injected by injector 18 into combustion chamber 20 .

FIG. 3 shows by way of example a simplified stroke and needle lift profile 44 of the injector 18 in partial lifting operation. At time T0 , injector 18 is triggered via control unit 22 by means of a so-called clock signal 46 . The injector 18 is only opened at time T1 after a time delay referred to as lift delay 48 . At time T2 the activation of injector 18 is ended by means of clock signal 46 and at time T3 the injector 18 is closed again. The time interval between times T0 and T2 is referred to as trigger duration 50 and the time interval between times T2 and T3 is referred to as off duration 52 .

FIG. 4 shows by way of example three flow activation characteristic curves 60 , 61 and 62 in the partial lift range for different injectors 18 . The characteristic curves 60 , 61 and 62 are offset approximately parallel to one another. The reason for this deviation is the different force balance inside the individual injectors 18 . These differences or sample deviations are based, for example, on different spring forces, different friction, different hydraulic closing forces or different magnetic forces.

It can be seen in FIG. 4 that the time shifts of the characteristic curves 60 , 61 and 62 are proportional to the respective boost delays 48 - 1 , 48 - 2 and 48 - 3 . The horizontal axis shows exemplary trigger durations in milliseconds. Boost delay 48 or boost delays 48 - 1 , 48 - 2 and 48 - 3 can be determined by means of characteristic curves 60 , 61 and 62 . Relative lift delays 48 are preferably determined with respect to an average value formed from lift delays 48 of a plurality of injectors 18 . The injector 18 can be, for example, the injector 18 present in the internal combustion engine 10 . It is also possible to determine an average value from a specific batch of injectors 18 and to specify lift delay 48 with respect to this average value. Other reference quantities are also conceivable. It is first of all important here to determine a variable for each injector 18 which allows conclusions to be drawn about its individual lift-off delay 48 .

FIG. 4 shows that an injector 18 with a characteristic curve 60 is raised early, so that its characteristic curve is shifted to the left, whereas an injector 18 with a characteristic curve 62 shown in FIG. 4 is raised particularly late, so that its characteristic The curve is shifted to the right. On the basis of the difference between boost delays 48 - 1 , 48 - 2 and 48 - 3 , it is possible to infer deviations of characteristic curves 60 , 61 and 62 from the above-described mean values. This is preferably done by means of calculations in the control unit 22 . This information is analyzed according to the invention in such a way that if the lift delay 48 of an injector 18 or its deviation from the mean value of a statistically significant number of injectors 18 is known, it can be determined therefrom. The quantity of fuel 42 metered by the injector 18 or the quantity deviation from the mean value of the fuel 42 passing the statistically significant number of injectors as a mean value 18 to be sure. By adjusting activation duration 50 , the fuel quantities to be dosed by injector 18 can be adjusted to a common mean value. This means that the fuel quantity deviation of this injector 18 can be adjusted to zero. Deviations in lift delay 48 of the individual injectors 18 thus act in the partial lift range as injector-specific offsets in the flow control characteristic curve.

An exemplary embodiment of the control method according to the invention is shown in the block diagram shown in FIG. 5 , which makes it possible to reduce fuel injection quantity deviations of the injector 18 . In this case, activation duration 50 is determined in a known manner from characteristic curve 64 as a function of fuel quantity setpoint 66 and the pressure in high-pressure line 16 , the so-called rail pressure 68 . The injector-specific lift-off delay 74 is ascertained in a known manner by suitable methods. The difference between lift delay 48 and mean value 70 is then determined, wherein mean value 70 describes the mean value of the lift delay of a statistically significant number of injectors 18 . Amplification factor k is applied to this injector-specific difference 72 and can thus be corrected for example by injector-specific difference 72 from triggering duration 50 and lift delay 48 by means of amplification factor k The correction value 74 is obtained by means of seeking the difference. An injector-specific triggering period 74 is thus determined, by means of which an injector-specific triggering operation can take place.

This is achieved with the method according to the invention or with the device according to the invention, that is, the deviations with respect to the fuel quantities injected into the combustion chamber 20 via the different injectors 18 are significantly reduced, which in turn can be significantly reduced. to improve combustion quality.

FIG. 6 shows a very simplified flow diagram of an exemplary embodiment of the method according to the invention. The individual steps of the method follow, for example, the block diagram shown in FIG. 5 . In step 100 , triggering duration 50 is ascertained from characteristic curve 64 as a function of quantity setpoint 66 and rail pressure 68 .

In step 110 a difference is determined from the provided injector-specific lift-off delay and the mean value 70 of a statistically significant number of injectors, for example stored in a memory area of the control device 22 , and this difference is compared with The magnification factor k is multiplied.

In step 120 , the injector-specific triggering period 74 is determined by combining the triggering period 50 determined in step 110 with the difference 72 , taking into account the amplification factor k, for example by taking a difference. get in touch.

The method according to the invention is preferably carried out continuously during operation of the internal combustion engine. As a result, the triggering duration can be corrected particularly sensitively or an injector-specific triggering time can be ascertained, whereby aging effects of the injector 18 can also be taken into account.

Claims (5)

1. the method triggered is carried out for the sparger (18) in the fuel injection apparatus of combustion motor (10), wherein said fuel injection apparatus comprises multiple sparger (18) and the fuel quantity wherein sprayed by means of sparger (18) depends on activation lasts time (50) of described sparger (18), it is characterized in that, for at least one sparger (18), depend on that the exclusive lifting of this sparger (18) delays (48) to try to achieve the exclusive activation lasts time (74), and the triggering for this sparger (18) depends on that the tried to achieve exclusive activation lasts time (74) carries out, fuel quantity deviation depends on that described lifting delays (48) to try to achieve, and described sparger exclusive activation lasts time (74) then depends on that described fuel quantity deviation is tried to achieve,

-from characteristic curve (64), depend on that fuel quantity (66) given in advance and the pressure (68) be present in rail (16) determine the activation lasts time (50),

-with the exclusive difference (72) of sparger for amplitude is revised described activation lasts time (50), difference between the mean value (70) that what the exclusive difference (72) of wherein said sparger was delayed by the lifting that sparger is exclusive that the lifting of the sparger (18) of (48) and quantity important statistically delays be kept in controller (22) is formed, and wherein considers that the exclusive difference (72) of described sparger is on the impact of average activation lasts time (50) by means of amplification factor (k).

2., by method according to claim 1, it is characterized in that, in the running of internal-combustion engine (10), try to achieve described lifting delay (48).

3. by the method described in claim 1 or 2, it is characterized in that, so determine the described exclusive activation lasts time (74), the corresponding fuel quantity with the described exclusive activation lasts time (74) is equivalent to for mean value common the middle sparger (18) existed of described internal-combustion engine (10).

4. by the method described in claim 1 or 2, it is characterized in that, described lifting is delayed (48) and is determined as the deviation of mean value (70), and wherein said mean value (70) is delayed middle formation from the lifting of the sparger (18) of quantity important statistically or delayed middle formation from the lifting of the sparger (18) be present in described internal-combustion engine (10).

5. for controlling and/or regulate the controller (22) that the fuel in internal-combustion engine (10) sprays, wherein said internal-combustion engine (10) comprises fuel injection apparatus and described fuel injection apparatus comprises multiple sparger (18) and the fuel quantity wherein sprayed by means of sparger (18) depends on activation lasts time of this sparger (18), it is characterized in that, described controller (22) comprises for determining at least one sparger (18) in described internal-combustion engine (10), depend on that the lifting of this sparger (18) is delayed the device of the exclusive activation lasts time (74) of (48) and comprises for depending on that the tried to achieve exclusive activation lasts time (74) triggers the device of this sparger (18), fuel quantity deviation depends on that described lifting delays (48) to try to achieve, and described sparger exclusive activation lasts time (74) then depends on that described fuel quantity deviation is tried to achieve,

-from characteristic curve (64), depend on that fuel quantity (66) given in advance and the pressure (68) be present in rail (16) determine the activation lasts time (50),

-with the exclusive difference (72) of sparger for amplitude is revised described activation lasts time (50), difference between the mean value (70) that what the exclusive difference (72) of wherein said sparger was delayed by the lifting that sparger is exclusive that the lifting of the sparger (18) of (48) and quantity important statistically delays be kept in controller (22) is formed, and wherein considers that the exclusive difference (72) of described sparger is on the impact of average activation lasts time (50) by means of amplification factor (k).