WO2010145936A1

WO2010145936A1 - Determination of the lift delay of a magnetic valve

Info

Publication number: WO2010145936A1
Application number: PCT/EP2010/057638
Authority: WO
Inventors: Klaus Joos; Ruben Schlueter; Jens Neuberg; Helerson Kemmer; Hans-Peter Lehr; Holger Rapp; Haris Hamedovic; Joerg Koenig; Anh-Tuan Hoang; Bernd Wichert
Original assignee: Robert Bosch Gmbh
Priority date: 2009-06-15
Filing date: 2010-06-01
Publication date: 2010-12-23
Also published as: DE102009026930A1; EP2443333B1; CN102803689B; CN102803689A; EP2443333A1

Abstract

The invention relates to a method for determining the opening delay time of a magnetic valve. The invention further relates to a control unit for actuating at least one magnetic valve in an injection system of an internal combustion engine. In order to determine a current opening delay time of a magnetic valve, it is proposed to execute an actuation of the magnetic valve during a measuring phase, and to determine a difference from the beginning of the actuation and the opening time of the magnetic valve. In order to determine the opening time, an actuation of the magnetic valve is carried out during a measuring phase. During the actuation, the actuating current is observed. If a change in the actuating current is detected, it is assumed that the opening time has been reached. Preferably, an at least approximately constant actuating voltage is applied to the magnetic coil during the measuring phase. Specifically, the predeterminable change is a flattening of the actuating current, which preferably is determined by determining a minimum of the differentiated power signal.

Description

description

title

Determining the lift-off delay of a solenoid valve

State of the art

The invention relates to a method for determining the opening delay time of a solenoid valve. The invention further relates to a control device for controlling at least one solenoid valve in an injection system in an internal combustion engine.

The invention also relates to a computer program executable on a computing device, in particular on a control device for controlling a solenoid valve.

Solenoid valves are electrically operated switching valves that are used in many areas for the metering of gases or liquids. For example, fuel injectors controlled by solenoid valves are used in internal combustion engines, which allow metering of the fuel required for combustion in the internal combustion engine. At the gasoline

Direct injection and common rail injection, the fuel is injected directly into the combustion chamber of the internal combustion engine. For the quality of combustion and thus the consumption and the exhaust behavior of the internal combustion engine, the metered amount of fuel is crucial. The metered amount of fuel is in turn of the

Opening period of the solenoid valve dependent. The opening duration is set via the activation duration of the solenoid valve coil provided in the solenoid valve, which is also referred to as the energization duration. In the case of common-rail injectors for diesel injection, the solenoid valve is designed as a servo valve and actuates a downstream high-pressure hydraulic system, which in turn controls the opening and closing movement of the nozzle needle controls. In gasoline direct injection, the valve needle of the injection nozzle is controlled directly by the solenoid valve.

The opening duration corresponds to the activation duration of the solenoid valve minus the so-called lift-off delay plus the so-called

Closing period. The lift-off delay describes the delay time from the start of control of the solenoid valve until the time of opening; the closing time describes the delay time from the control end to the time of closing the solenoid valve.

If the opening duration is known, suitable control methods can be used in order to optimally set the activation duration of the solenoid valve.

Disclosure of the invention

The object of the invention is to provide a method and a device for determining an opening delay time or a lift-off delay of a solenoid valve, wherein the opening delay time is as current as possible so that specimen scattering on the one hand and, for example, aging phenomena on the other hand can be taken into account and optimized fuel metering is made possible.

The object is solved by the features of independent claims 1, 10 and 12. Further advantages of the invention will become apparent from the features mentioned in the dependent claims.

According to the invention, a control of the magnetic coil is performed in a measuring phase and it is determined a difference from the beginning of the control and from the opening time of the solenoid valve. For the determination of the opening time in the measuring phase, a control of the solenoid valve is performed. During drive, the drive current is observed. If a change in the drive current is detected, it is concluded that the opening time has been reached. Preferably, an at least approximately constant driving voltage is applied to the magnetic coil in the measuring phase. This is a sure recognition of a change in the

Control current ensures that the change is not from a changed Activation results, but from the behavior of the magnetic coil itself. The predetermined change is in particular a flattening of the drive current, which is preferably determined by determining a minimum of the differentiated current signal.

The advantage of the invention is a further reduction of the specimen spread of the injection quantity, since the method according to the invention can be applied individually for each solenoid valve. This is achieved by incorporating the tolerance-related opening delay time in the control method. The quantity control in the metering of

Fuel quantity then takes place by regulating the opening duration. By measuring the opening delay time in a separate measurement phase, the drive voltage of the solenoid valve can be freely selected and is not subject to the restrictions during normal operation of the internal combustion engine. The measuring phase can be initiated automatically at certain times or at certain operating points.

The opening delay time is determined from the difference between the opening time of the solenoid valve and the start of control, wherein the start of control is known and the opening delay time according to the invention is determined from the current profile of the drive current of the solenoid valve. For this purpose, a largely constant voltage is applied to the magnetic coil from the start of control and the drive current of the solenoid valve is detected and monitored, for example via a so-called measuring shunt. A measuring shunt is a low-resistance electrical resistance, also known as a shunt resistor. It has been observed that from the moment the solenoid valve is opened, the current flow of the drive current flattens out. This flattening of the current signal is used according to the invention for detecting the opening time.

A detection of the flattening of the current signal can be determined, for example, by determining the minimum of the differentiated current signal. The differentiation and determination of the minimum can be done either partially or entirely by analog preprocessing or by digital signal processing by means of a microcontroller. The opening time of the solenoid valve is dependent on the electrical voltage of the drive current, by means of which the solenoid valve is controlled. Advantageously, therefore, the opening time is determined in one or more operating points, each with a defined drive voltage. From each opening time so determined can for more

Ansteuerspannungen the opening behavior or the opening time are extrapolated.

In principle, the measuring phase can also be carried out during normal activation of the solenoid valve. Advantageously, however, an at least approximately constant drive voltage is selected to ensure reliable detection of the opening time.

Of particular importance is the realization of the invention in the form of a computer program on a computing device, in particular on a

Control unit for controlling and / or regulating a fuel injection in an internal combustion engine, is executable, wherein the computer program is programmed for carrying out the method according to the invention. The computer program is preferably stored on an electronic or optical storage medium.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments of the invention are shown. The features mentioned in the claims and in the description may be essential to the invention individually or in any desired combination.

Show it:

1 is a highly schematic representation of an internal combustion engine with a fuel injection system and a plurality of solenoid valves,

Figure 2a is a schematic detail view of an exemplary embodiment of a solenoid valve in a closed

Operating condition Figure 2b is a schematic detail view of an exemplary

Embodiment of a solenoid valve in an open operating state,

Figure 3 is a schematic representation of the current, voltage and

Ventilhubverlaufs a solenoid valve,

FIG. 4 is a schematic representation of an exemplary current profile, a derivation of the current profile and of the

Needle strokes for two different electrical voltages of the drive current,

Figure 5 is a schematic flow diagram of an embodiment of the method according to the invention.

FIG. 1 shows an internal combustion engine 10, which comprises a fuel reservoir 12, from which fuel is conveyed into a high-pressure fuel line 16 by means of a delivery system 14. The high pressure line 16 is formed for example as a common rail. The

High-pressure line 16 is connected to solenoid valves 18, which allow fuel to be injected directly into each of the solenoid valves 18 associated combustion chambers 20. The operation of the internal combustion engine 10 and in particular the fuel injection system, which is formed for example by the conveyor system 14, the high pressure line 16 and the solenoid valves 18 is controlled by a control and regulating device, such as a control unit 22. The control unit 22 enables the acquisition of input values and the provision of output values or the actuation of actuators, in particular the activation of the solenoid valves 18.

In Figure 2, a solenoid valve 18 shown in Figure 1 is shown schematically enlarged. The solenoid valve 18 has an electromagnetic actuator which has a magnetic coil 26 and a magnetic armature 30 cooperating with the magnetic coil 26. The magnet armature 30 is connected to a valve needle 28, that it relative to a direction of vertical movement in FIG Valve needle 28 is movable. A valve spring 36 exerts a spring force on the valve needle 28, so that it is held in a valve seat 38.

A control of the solenoid valve 18 by the controller 22 causes energization of the solenoid 26, causing the armature 30 moves upward so that it moves out of its valve seat 38 against the spring force, engaging in a stop the valve needle. This situation is shown in FIG. 2b. There, fuel 42 can now be injected from the solenoid valve 18 into the combustion chamber 20.

FIG. 3 shows the characteristics of a drive current 60, a drive current 61 and a valve lift 62 of the solenoid valve 18.

The control of the solenoid valve 18 begins at a time TO. At a time T1, the opening of the solenoid valve 18 takes place. The period between

TO and T1 is referred to as lift-off delay or opening delay time toi. At a time T2, the solenoid valve 18 is opened. The time span t ₁₂ denotes the opening duration of the solenoid valve 18.

At a time T4, the control of the solenoid valve 18 ends and in one

Time T5, the closing operation of the solenoid valve 18 takes place with a time delay t _45th The time delay t ₄₅ corresponds to the difference between the time T5 and the time T4. At a time T6, the solenoid valve 18 is closed.

The situation shown in Figure 3 shows a normal operation of the solenoid valve 18, for example during operation of an internal combustion engine 10, to meter the fuel 42 required during combustion. For this purpose, a particularly high voltage is applied to the solenoid valve 18, initially in a so-called boost phase t _O2 , in order to achieve a current increase as quickly as possible. In the so-called battery phase t ₂₃ , the voltage of the drive current is reduced; This completes the current increase phase. Between the times T3 and T4, the solenoid valve 18 is driven by individual voltage pulses, which cause a get the drive current. The so-called open time t ₁₆ can thus be determined as follows:

This means that the opening time t ₁₆ from the drive time. _O4 can be determined, wherein the opening delay time t _{01 is} subtracted from the drive time t ₀₄ and the closing delay time t _{46 is} added.

FIG. 4 shows by way of example two current curves 60a, 60b, discharges 70a, 70b of the current profiles 60a, 60b and needle lift profiles 80a, 80b during a measurement phase according to the invention. In the curves 70a and 70b it can be seen that the respectively significant local minima correspond to the times T1a and T1b at which an opening of the solenoid valve 18 takes place.

In the measuring phase, a constant drive voltage of the valve is selected.

This must also be ensured if the measurement phase takes place during operation of the internal combustion engine, since otherwise a reliable detection of the opening time from the current flow is not possible.

During operation of the internal combustion engine 10, it is not ensured in all operating ranges that during normal activation of the solenoid valves 18 at the end of the current increase phase, ie the boost phase t _02, the opening time T1 is actually reached. The boost phase with normal control of the solenoid valves 18 can not be extended arbitrarily until the opening time T1 of the solenoid valve 18 is reached safely because the

Solenoid valve 18 would hit by the necessary high energy coupling at too high speed to the upper valve stop. Preferably, therefore, a measurement of the opening timing T1 is performed only in selected operating areas. Alternatively or additionally, the measurements can be carried out in a separate measurement phase.

During such a measurement phase, suitable drive voltages can then be selected, which are advantageously below the valve drive voltages which are used during the normal activation, that is to say, for example, during normal injections. Due to the lower drive voltage during the measurement phase, the measured opening delay time t _{01 is extended} . This is why in the subsequent an operating drive voltage resulting opening delay time converted. Since the actual opening delay time is considerably smaller than the measured opening delay time, measurement inaccuracies only have a greatly attenuated effect on the actual activation.

Preferably, a real-time signal evaluation of the current profile is performed during the separate measurement phase. As soon as the opening time T1 is detected, the measuring phase is aborted immediately. As a result, the injection of an undesirable amount of fuel can be avoided, but at least reduced. If a low drive voltage is selected, the opening accuracy of the valve needle 28 is reduced, as a result of which the possibly unintentionally injected fuel quantity 42 is reduced to a level that is not relevant to the internal combustion engine 10.

FIG. 5 shows a highly schematic flow diagram of an embodiment of the method according to the invention. The method begins in a step 100 in which the measurement phase is started. In particular, a control of the solenoid valve 18 takes place here by means of the drive current 60. In a step 101, the drive current 60 is detected and monitored. In step 101, for example, the derivative 70a, 70b of the detected drive current 60 is formed.

In a step 102, it is checked whether there is a change of the driving current 60 indicating the reaching of the opening timing T1. For this purpose, for example, the course of the derivative 70a, 70b of the drive current 60 is then examined as to whether a local minimum exists. If this is not the case, then step 101 continues to monitor.

If, however, the presence of the opening time T1 is detected in step 102, the determined opening time is stored in a suitable characteristic field in a step 103, optionally after compensation of effects resulting from a slightly selected drive voltage in the measurement phase. In a step 104, opening times are extrapolated from the determined opening times for further operating points and likewise into the

Map stored.

Claims

claims

1 . A method for determining the opening delay time (t _O i) of a solenoid valve (18), characterized in that in a measuring phase, a control of the solenoid valve (18) takes place and a difference from the beginning of a control and from the opening time (T1) of the solenoid valve (18 ) is determined, wherein for the determination of the opening time (T1) a control of the solenoid valve (18) takes place in the measurement phase, while driving the drive current (60) is observed and upon detection of a predetermined change in the drive current (60) on reaching of the opening time (T1) is closed.

2. The method according to claim 1, characterized in that in the measuring phase, an at least approximately constant driving voltage (60a, 60b) is applied to the solenoid valve (18).

3. The method according to claim 1 or 2, characterized in that the observation of the drive current (60; 60a, 60b) takes place by means of a measuring shunt.

4. The method according to any one of the preceding claims, characterized in that the predetermined change describes a flattening of the drive current (60; 60a, 60b).

5. The method according to claim 4, characterized in that the flattening is determined by determining a minimum of the differentiated drive current

6. The method according to any one of the preceding claims, characterized in that the opening time is determined in at least one operating point with a defined driving voltage and from the Opening time (T1) the opening behavior is extrapolated for at least one other driving voltage to another operating point.

7. The method according to any one of the preceding claims, characterized in that the opening delay time in a separate

Measuring phase is determined so that the drive current (60, 60a, 60b) of the solenoid valve (18) in the measuring phase is independent of the control of the solenoid valve (18) for the purpose of injection.

8. The method according to claim 7, characterized in that in the separate

Measuring phase, the drive voltage is chosen so that it is below the drive voltage applied during normal operation of the solenoid valve, and that the calculation of the occurring during normal operation opening delay time (T1) is calculated on the basis of the determined in the separate measurement phase opening delay time.

9. The method of claim 7 or 8, characterized in that during the measurement phase of the opening time (T1) is determined by means of a real-time signal evaluation and the measurement phase is aborted when the opening time (T 1) is detected.

10. Control device (22) for controlling at least one solenoid valve (10) in an injection system in an internal combustion engine (10), characterized in that the control device (22) is prepared for carrying out a method according to one of claims 1 to 9.

1 1. Control unit (22) according to claim 10, characterized in that the control unit (22) for controlling the solenoid valves (18) is prepared in the measurement phase with such a low drive voltage, that the injected during the measurement phase amount of fuel (42) to one for the

Operation of the internal combustion engine (10) is not relevant measure reduced.

12. Computer program, which is executable on a computing device, in particular on a control unit (22) for controlling a solenoid valve (18), characterized in that the computer program for performing A method according to any one of claims 1 to 9 is programmed when the computer program is executed on the computing device.