DE102007037036A1 - Internal combustion engine controlling and regulating method, involve interpreting increase of voltage as end of injection, and setting beginning and end of injection as decisive factor for subsequent control and regulation of engine - Google Patents

Abstract

The method involves setting a control flow for an injector (2) to a desired value for initiation of injection by an electronic control unit (1). The control flow is set to another value when a temporal, significant deviation from the former value arises, where the deviation is interpreted as beginning of injection. Temporal increase of voltage at an actuator (3) is caused, where the increase of voltage is interpreted as end of injection ending. The beginning and end of the injection are set as a decisive factor for subsequent control and regulation of the engine. An independent claim is also included for a device for performing an internal combustion engine controlling and regulating method.

Description

The The invention relates to a method for controlling and regulating a Internal combustion engine and a device for execution the method in which by an electronic control unit via an injector initiates or terminates an injection and in which a means for detecting integrated in the injector the opening / closing of the nozzle needle an injection start or injection end is detected.

to Compliance with the statutory emissions regulations is the exact control the start of injection and the end of injection required. Due to the Signal propagation times, disturbances and aging of the components, the actual injection start deviates from the desired injection start. So For example, there is a significant time offset from the output of the start of energization from the electronic control unit the injector, the needle stroke and the actual injection start. For the injection end this applies accordingly.

In an internal combustion engine with a common rail system, the actual injection start and the actual injection end are usually determined from secondary measured variables. So that beats DE 31 18 425 A1 a method in which measured the fuel pressure, filtered and then interpreted by differentiation of the filtered pressure curve, the extreme values as start of injection and injection end. At one of the DE 103 44 181 A1 known method is measured and stored in a common rail system with individual storage of the individual storage pressure curve. An injection end is then calculated from the stored individual accumulator pressure profile, and a virtual injection start is calculated via a mathematical function.

Another common measure for determining the actual injection start and the actual injection end is in practice to detect the opening or closing of the injector nozzle needle via a seat contact switch. In this solution, the nozzle needle corresponds to the first contact of the switch and the injector corresponds to the second contact of the switch. The nozzle needle is connected to a positive electrical potential, while the injector housing with the needle seat is at a reference potential (ground). If the nozzle needle lifts off the needle seat, the seat contact switch opens. This is detected by the electronic control unit as actual injection start. When the nozzle needle comes into contact with the needle seat, the seat contact switch closes. From the electronic control unit this is detected as actual injection end. The measured actual injection start and the measured actual injection end are then set as decisive for the further control and regulation of the internal combustion engine. So that the state of the seat contact switch can be detected by the electronic control unit as a confirmed size, two connecting lines are required. To control the integrated in the injector actuator, which then the position of the nozzle needle is controlled, a third connecting line is required. Such a method and such a device is for example from the DE 196 52 719 A1 known. In everyday use, the interfaces from the control unit to the wiring harness and from the wiring harness to the injector due to the environment are a potential source of error.

The opening or closing of the injector nozzle needle can also be opto-electronically ( JP 58 20 68 72 A1 ), inductive or capacitive ( DE 198 30 667 A1 ). The problem described above remains acute even in these embodiments.

Of the The invention is therefore based on the object, a safe and reliable Provide start of injection and injection end detection.

The The object is achieved by a method having the features of claim 1 and a correspondingly adapted device for implementation the method with the features of claim 7 solved. The embodiments are in the dependent claims shown.

To the Initiation of an injection is by the electronic control unit a drive current for the injector to a first setpoint set, wherein in the injector at least one actuator for controlling a nozzle needle, an energy storage and a means for detecting the opening / closing the nozzle needle are integrated. With the drive current both the actuator and the energy storage acted upon, causing the Energy storage, such as a capacitor is charged. By opening the nozzle needle is then the energy relocated from the energy storage in the actuator. The energy transfer causes a temporary, significant deviation from the first set point of the drive current. This deviation is detected in the electronic control unit via a current measurement on the supply side. A detected deviation is interpreted by the electronic control unit as start of injection.

To end an injection, the electronic control unit sets the drive current to a second desired value. With closing of the nozzle needle, the energy is then transferred from the energy storage in the actuator, whereby a temporary increase in the voltage applied to the actuator occurs, which is interpreted by the electronic control unit as the injection end. The detected start of injection and the detected injection end are then set as decisive for the further control and regulation of the internal combustion engine. For the purpose of According to the invention, the means for detecting the opening or closing of the nozzle needle comprises both optoelectronic, inductive or capacitive solutions and a seat contact switch.

The Device for carrying out this method is through a 2-wire interface marked. Compared to the The prior art therefore results in a reduced cabling effort. From Advantage is the real-time capability, resulting in a fast adapted response to the situation. moreover the process can be easily integrated into the existing control program integrate. Because hardware changes to the electronic control unit are required only to a small extent, are the implementation costs of the invention moderate.

to Increase in process reliability when detecting the start of injection a first time window is set upon initiation of the injection and the start of injection is interpreted as authoritative if the deviation from the first setpoint of the drive current within of the first time window is detected. If no deviation occurs or is the deviation from the first setpoint of the drive current outside the time window, the start of injection is considered faulty set and the last valid start of injection as relevant maintained. The evaluation of the injection end is analogous to this, wherein for the assessment of the temporary increase of voltage applied to the actuator is used.

to precise adaptation to the actual state of the system the duration of the temporary increase in the actor measured voltage applied. This duration is called by the so-called Nozzle coefficient influenced. The Nozzle coefficient is a constant in the calculation of the target fuel amount, which from the manufacturer of the injector on a component test bench is determined. In other words: from the duration of the temporary Increase can be the individual behavior Derive the injector and use for adaptive control, for example for truancy.

In The drawings is a preferred embodiment shown. Show it:

1 the output side of the controller with an injector as a block diagram,

2A to 2D an injection process as a time diagram,

3 a voltage-time diagram and

4A and 4B a program schedule.

The 1 shows the output side of the electronic control unit 1 and an injector 2 as a block diagram. Connected are the control unit 1 and the injector 2 via a 2-wire interface with a first line L1 and a second line 12 , which are executed in practice as a twisted pair. In the injector 2 Among others, an actuator is integrated 3 for controlling a nozzle needle, an energy storage 4 and a means for detecting the opening / closing of the nozzle needle. The general structure and functionality of an injector will be assumed to be known in the text below. The term actuator is to be understood as an actuator both a coil and a piezo stack. The energy storage 4 is in the simplest form a capacitor. The detection means may be opto-electronic, inductive, capacitive or designed as a seat contact switch. In the further text, the invention will be described with reference to a seat contact switch. The seat contact switch SK is formed by the electrical contact point nozzle needle / injector housing, wherein the nozzle needle at a positive potential, for example, 42 volts, and the injector on reference potential, usually ground, are. The closing contact can also be formed by a single piezoelectric element within a piezo stack, as for example from the DE 101 29 375 A1 is known.

The following components are located on the output side of the control unit: a measuring resistor 5 (Shunt), a first comparator 6 , a first switch S1, a second comparator 7 for potential measurement and a second switch S2. Via the first switch S1, the current path from the supply side to the injector 2 switched and via the switch S2, the current path from the injector 2 clocked to the reference potential. If both the first switch S1 and the second switch S2 are closed, a closed circuit is produced by the voltage source, potential Ub, via the measuring resistor 5 , first switch S1, first line L1, actuator 3 with parallel energy storage 4 , second line 12 and second switch S2 to the reference potential. About the first comparator 6 becomes the potential difference at the two poles of the measuring resistor 5 detected, which is proportional to the drive current iAN. The value of the drive current iAN is represented by the output signal A1 of the first comparator. The potential difference between the two potentials V1 and V2 corresponds to the voltage at the actuator 3 , This potential difference is made by the second comparator 7 detected and displayed as an output signal A2.

The arrangement has the following functionality:
From the electronic control unit 1 For initiating an injection, the first switch S1 and the second switch S2 are closed and the drive current iAN for the injector 2 to a first setpoint set. About the measuring resistor 5 and the first comparator 6 the current value is recorded. With the drive current iAN becomes the actuator 3 and the energy storage 4 charged, causing the energy storage 4 is charged. The energization of the actuator 3 causes the nozzle needle to lift off the needle seat, the seat contact switch SK opens and the two terminals of the actuator 3 the potentials of the energy storage 4 issue. Because the positive potential of the energy storage 4 is higher than the first potential V1, a current flows from the energy storage 4 to the actor 3 , In other words: the energy comes from the energy store 4 in the actor 3 rearranged. Due to the energy transfer, no current flows through the measuring resistor 5 , The drive current iAN drops to zero amperes for a limited time. The duration is determined by the storage capacity of the energy store 4 established. This temporary, significant deviation of the drive current iAN from the setpoint is interpreted as start of injection. After the energy store 4 has given up his energy become the actor 3 and the energy storage 4 again from the control unit 1 provided. To end the injection, the first switch S1 and the second switch S2 are opened. As the energy storage 4 is now filled again, the energy is again in the actuator 3 rearranged. This energy transfer causes a temporary increase in the voltage applied to the actuator UAK. This voltage increase is via the second comparator 7 detected on the basis of the potential difference of the two potentials V1 and V2. From the control unit 1 this is interpreted as splashing. The further control and regulation of the internal combustion engine then takes place on the basis of the detected injection start and detected injection end.

In the 2 an injection process is shown. The 2 consists of the subfigures 2A to 2D , These show in each case over time: the course of the drive current iAN ( 2A ), the current flow iAK at the actuator ( 26 ), the energy output of the energy store ( 2C ) and the switching state of the seat contact switch SK ( 2D ). In the 2 B is shown as a dashed line the curve of the voltage UAK on the actuator.

At a time t1 an injection is initiated by the control unit setting the drive current iAN to a first setpoint value iSL1 and at the same time starting a first time step tS1, of, for example, 500 μs. To setpoint iSL1 corresponds to the corresponding current iAK1 at the actuator. At the end of the first time stage tS1, a first time window ZF1 with a predefined time duration dt1, for example 200 μs, is set. The first time window ZF1 serves to improve the process reliability by checking whether the start of injection occurs within the first time window ZF1. At time t2, the nozzle needle lifts off the needle seat, whereby the seat contact switch SK opens. In the 2D Therefore, the state signal changes from 0 to 1. Due to the open seat contact switch SK, the energy from the energy storage in the actuator for the period t2 / t3 rearranged, see energy level E1 in 2C , The energy transfer causes within the period t2 / t3, the drive current iAN drops significantly below the first setpoint iSL1. The significant deviation of the drive current iAN from the setpoint iSL1 is interpreted as start of injection. In 2A the deviation is indicated by the reference symbol di. Since the deviation di was detected within the first time window ZF1, the start of injection is correct. The deviation is not apparent on the current signal iAK of the actuator, since in the period t2 / t3 the actuator draws its energy from the energy store. At time t4, the drive current iAN is set to a lower level because the nozzle needle is fully open at its mechanical end stop. This reduced drive current is maintained until time t5. At time t5, the injection is terminated by setting the drive current iAN to a second setpoint value iSL2, here: zero ampere.

At the same time, a second time step tS2, for example 800 μs, is started. In its connection, a second time window ZF2 is set for a predefinable time period dt2, for example 400 μs, see 2 B ,

It is assumed that at time t6, the nozzle needle comes to rest on the needle seat, whereby the seat contact switch SK closes. In the 2D Therefore, the waveform changes from the value 1 to zero. Due to the closed seat contact switch, energy is again transferred from the energy store to the actuator during the period t6 / t7, see energy level E1 in 2C , This energy transfer causes a voltage pulse, which is interpreted by the electronic control unit via the second comparator as injection end. Since the injection end is within the second time window ZF2, the detected injection end is set as valid.

Becomes determined that no deviation di of the drive current iAN from Setpoint iSL1 occurs or the deviation di outside of the first time window ZF1, the measurement is discarded and the last valid start of injection has been set as definitive. If there is no increase in the voltage UAK on the actuator or the increase is outside the second time window ZF2, the measurement is discarded and the last injection end set as authoritative.

In the 3 is for the injection end as a solid line the voltage curve UAK on the actuator and as a dotted line the state of the seat Contact switch SK shown for comparison. The voltage curve was recorded on a coil as an actuator. Before the time t6, the Sitzkontaktschlalter SK is open and the actuator is no voltage. At time t6, the seat contact switch SK closes because the nozzle needle comes to rest on the needle seat. In the figure, the signal of the seat contact switch SK changes to zero. As a result of the closed seat contact switch SK, the energy is transferred from the energy storage in the actuator, whereby the voltage at the actuator increases to the positive value U1. At time t7, the energy store has given up all its energy, so that initially the voltage at the actuator drops. From the time period t6 / t7, ie the duration of the deviation, it is possible to deduce the so-called nozzle coefficient. The nozzle coefficient is a constant in the calculation of the desired fuel quantity, which is determined by the manufacturer of the injector on a component test bench. In other words: From the duration of the deviation, the individual behavior of the injector can be derived and used for adaptive control, for example for truancy control. The voltage pulse in the period t6 / t7 is recognized by the control unit as the end of injection. Due to the self-induction, the collapsing magnetic field in the coil produces a negative voltage pulse, value U2, with asymptotic progression in the period t7 / t8.

In the 4 the process is shown as a program flow, the 4A a first part of the program and 4B represents a second part of the program. At S1, the drive current iAN is set to the first setpoint value iSL1 and the first time step tS1, for example 500 μs, is started. Thereafter, it is checked at S2 whether the first time step tS1 has expired. If this still runs, query result S2: no, branches back to point A back. If the first time step tS1 has expired, query result S2: yes, then the first time window (ZF1) is set at S3 for a predefinable period dt1, for example 200 μs. At S4, it is checked whether a significant deviation of the drive current iAN from the setpoint iSL1 is detected. For this purpose, the measured value can be compared with the desired value iSL1 (as shown) or the difference of these two values can be calculated and compared with a limit value (iSL1-iAN> limit value). If no significant deviation is detected, the program part is passed through steps S6 to S8. If a significant deviation is detected, the program part is passed through step S5.

If a significant deviation of the drive current iAN from the first setpoint value iSL1 is determined at S4, query result S4: yes, the detected injection start SB is set as definitive at S5 and the program at point 1 of FIG 4B continued. If, on the other hand, no significant deviation is found at S4, query result S4: no, then it is checked at S6 whether the end of the first time window (ZF1) has been reached. If this is not the case, query result S6: no, the program branches back to point B and the program is continued again with S4, that is, it waits until the expiration of the first time window (ZF1). If the end of the first time window is determined at S6, query result S6: yes, the detected injection start SB is classified as faulty at S7 since it could either not be detected or was outside the first time window. Thereafter, at S8, the last valid injection start SB is set as authoritative and the program at point 1 of 4B continued.

In the 4B the second part of the program is shown. At S9, the injection is terminated by setting the drive current iAN to a second setpoint iSL2. The second set value iSL2 preferably corresponds to zero amps and is set by opening the first switch S1. At the same time, a second time step tS2, for example 800 μs, is started. Thereafter, a query is made at S10 as to whether the second time step tS2 has expired. If this is not the case, query result S10: no, it waits until the second time step tS2 has expired. At S11, a second time window (ZF2) is subsequently set for a predefinable time dt2, for example 400 μs. At S12 it is checked whether a temporary increase in the voltage UAK was detected at the actuator, for example by the detected actuator voltage UAK is compared with a positive limit GW.

Becomes at S12 found that the actuator voltage UAK larger when the limit value GW is, query result S12: yes, so at S13 the detected injection end SE as authoritative set and the program ends. If otherwise, it is determined at S12 that the actuator voltage UAK is not greater than the limit value GW is, query result S12: no, then it is checked at S14, whether the end of the second time window (ZF2) has been reached. Is this not the case, query result S14: no, branch back to point E and the program continues again with S12, ie until the expiration the second time window (ZF2) waited. At S14, the end of the second time window detected, query result S14: yes, it will at S15, the detected injection end SE is classified as defective, either no increase in the voltage UAK detected on the actuator or because it was outside the second window of time. Thereafter, at S16, the last valid injection end SE becomes decisively set and the program ended.

• – Das Verfahren ist echtzeitfähig, wodurch eine schnelle an die Situation angepasste Reaktion bei der Steuerung und Regelung möglich ist;
• – Die Umsetzung der Erfindung erfolgt über eine 2-Drahtschnittstelle, wodurch ein reduzierter Verkabelungsaufwand erreicht wird;
• – Das erfindungsgemäße Verfahren lässt sich problemlos in das bestehende Steuerungsprogramm integrieren und verursacht nur moderate Kosten in der Umsetzung.

The method has been described on the basis of a single injection, but can also be used for multiple injections with pre-, main- and post-injection. Zusammenfas send arise for the invention from the description the following advantages:

• - The method is real-time capable, allowing a fast adapted to the situation reaction in the control and regulation;
• - Implementation of the invention via a 2-wire interface, whereby a reduced cabling effort is achieved;
• - The inventive method can be easily integrated into the existing control program and causes only moderate costs in the implementation.

1

electronic control unit

2

injector

3

actuator

4

energy storage

5

measuring resistor

6

first comparator

7

second comparator

S1

first switch

S2

second switch

SK

Seat contact switch

L1

first management

L2

second management

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3118425 A1 [0003]
• DE 10344181 A1 [0003]
• - DE 19652719 A1 [0004]
• - JP 58206872 A1 [0005]
• - DE 19830667 A1 [0005]
• - DE 10129375 A1 [0018]

Claims (7)

Method for controlling and regulating an internal combustion engine, in which for initiating an injection by an electronic control unit ( 1 ) a drive current (iAN) for an injector ( 2 ) is set to a first desired value (iSL1), wherein in the injector ( 2 ) at least one actor ( 3 ) for controlling a nozzle needle, an energy store ( 4 ) and a means for detecting the opening / closing of the nozzle needle are integrated, with the drive current (iAN) of the actuator ( 3 ) as well as the energy storage ( 4 ) are acted upon, in which the opening of the nozzle needle, the energy from the energy storage ( 4 ) in the actuator ( 3 ), whereby a temporary, significant deviation (di) from the first set value (iSL1) of the drive current (iAN) occurs, which the electronic control unit ( 1 ) is interpreted as start of injection (SB), in which to terminate an injection from the electronic control unit ( 1 ) the drive current (iAN) is set to a second setpoint value (iSL2), in which the energy from the energy store (i) is closed by closing the nozzle needle (i) 4 ) in the actuator ( 3 ), whereby a temporary increase of the voltage applied to the actuator (UAK) occurs, which from the electronic control unit ( 1 ) is interpreted as the injection end (SE), and in which the injection start (SB) and the injection end (SE) are set as decisive for the further control and regulation of the internal combustion engine. Method according to claim 1, characterized in that that with initiation of the injection a first time window (ZF1) is set and the start of injection (SB) interpreted as authoritative when the deviation (di) from the first command value (iSL1) of the drive current (iAN) is detected within the first time window (ZF1). A method according to claim 2, characterized in that the injection start (SB) is set as faulty if the deviation (di) from the first setpoint (iSL1) of the drive current (iAN) does not occur or outside the first time window (ZF1) is detected, and at a set as incorrect injection start (SB) the last valid start of injection as relevant maintained becomes. Method according to claim 1, characterized in that that with completion of the injection a second time window (ZF2) is set and the injection end (SE) interpreted as authoritative becomes when the increase of the voltage applied to the actuator (UAK) within the second time window (ZF2) is detected. Method according to claim 4, characterized in that the injection end (SE) is set as faulty when the increase The voltage applied to the actuator (UAK) does not occur or outside of the second time window (ZF2) is detected, and one as faulty set splash (SE) the last valid injection end is maintained as authoritative. Method according to claim 4, characterized in that that the duration of the increase in the voltage applied to the actuator (UAK) is measured, the duration of a nozzle coefficient assigned and, on the basis of the nozzle coefficient, a spray quantity correction is determined. Device for carrying out the method with the features of claim 1, characterized in that the electronic control device ( 1 ) and the injector ( 2 ) are connected to each other via a 2-wire line to initiate or terminate the injection and to detect the temporary significant deviation (di) from the first setpoint (iSL1) of the drive current (iAN) and to detect the temporary increase in the voltage applied to the actuator (UAK) are.