WO2015039953A1

WO2015039953A1 - Method and device for detecting operating states of an electromagnetically driven device

Info

Publication number: WO2015039953A1
Application number: PCT/EP2014/069433
Authority: WO
Inventors: Nikolay Belyaev; Frank Denk; Christian Hauser; Markus Stutika
Original assignee: Continental Automotive Gmbh
Priority date: 2013-09-19
Filing date: 2014-09-11
Publication date: 2015-03-26
Also published as: DE102014202136B4; DE102014202136A1

Abstract

The invention relates to a method for determining the point in time of a predetermined operating state of an electromagnetically driven device having a coil drive, in particular of an injector for injecting fuel. The method comprises the following: (a) applying a predetermined control voltage to the coil drive, wherein an alternating voltage, which is set to excite an oscillating circuit containing the coil drive, is superposed on at least part of the control voltage, (b) recording the temporal progression of the current intensity (I) of a current flowing through the coil drive, (c) extracting a current oscillation (9) corresponding to the superposed alternating voltage from the recorded temporal progression of the current intensity of the current flowing through the coil drive, and (d) determining a point in time (10) at which an amplitude change occurs in the extracted current oscillation (9), wherein the determined point in time is the point in time of the predetermined operating state. The invention further relates to an apparatus, to a motor controller, and to a computer program.

Description

description

Method and device for detecting operating states of an electromagnetically driven device

The present invention relates to the technical field of detection of operating states of an electromagnetically driven device, in particular an injector for fuel ^¬ injection.

Electromagnetically driven assemblies can be operated with low tolerance in the full stroke. Using the example of an injector for fuel injection, this mode of operation means the movement of the injector needle up to a maximum deflection and the variation of the fuel mass by the variation of the injection time.

The trend towards smaller injection quantities with simultaneously higher static flow increasingly requires mastery of ballistic operation at the injector. Under the ballistic injector operation means the Teilauslenkung the Injek ^¬ tornadel in a predetermined design parameters by electrical and after completion of the introduction of force that is free parabolic flight path without reaching the full stop. In contrast to the full stroke of the ballistic operation of the injector is much more subject to tolerances, since here both electrical and mechanical tolerances affect the course of the opening more than is the case in Vollhubbetrieb. For ballistic injector operation, the following tolerances must be distinguished, which may occur separately or superimposed:

A compensation of the tolerances is known to be possible. The measurement of the characteristic voltage superimposed on the coil current or the voltage is preferably used in the patent application DE 3843138A1. It is known that on coil-operated assemblies a feedback signal can be obtained by the eddy current driven coupling between the mechanics (valve and injector needle) and magnetic circuit (coil) is used for signal generation. The physical effect is due to the speed-dependent self-induction in the electromagnetic circuit due to the movement of the armature and the injector needle. In dependency of the transmission speed BEWE ^¬ a voltage (charakteris ^¬ tables voltage) is duced in ^¬ in the solenoid, which is superimposed on the drive signal.

The utilization of this effect requires that the superimposition of the basic electric variable voltage or current is suitably separated with the signal change by the needle movement and then further processed. The characteristic waveform in the voltage or current signal is evaluated with respect to the time of occurrence.

Especially for the detection of the opening, the evaluation of the characteristic waveform is problematic. Since the magnetic circuit is typically in saturation when opened, the reaction to the magnetic circuit is minimal and thus difficult to detect. One solution is to actively change the drive to ensure that the magnetic circuit is not in saturation. However, the behavior of the injector changes, which requires a subsequent transfer to standard operation.

Previously known methods for the general determination of the opening or closing time of an electromagnetically driven device either each use a measuring channel for determining the injector opening and closing

(Current / voltage measurement) with intervention in the current application in the opening detection or only the current measurement for opening and closing time detection with the already described intrusive intervention in the basic control of the coil and the associated limitations. In this case, a detection of injector opening is only possible if the injector is operated in Vollaussteuerung. This requires the need for transmission of the adaptation value of

Full control on the ballistic operation. Through this transfer, additional sources of error are possible, which may no longer be tolerated in the case of highest accuracy requirements.

The present invention has for its object to provide an improved and simple determination of operating conditions of an electromagnetically driven device.

This object is solved by the subject matters of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a method for determining the time of a predetermined Betriebszu ^¬ condition of a coil drive having electromagnetically driven device, in particular an injector for fuel injection is described. The described method comprises: (a) acting on the coil drive with a predetermined drive voltage, wherein at least a part of the drive voltage is superimposed with an alternating voltage, which is adapted to excite a resonant circuit, which the

Coil drive comprises, (b) detecting the time course of the current of a current flowing through the coil drive current, (c) extracting a superimposed AC voltage corresponding current oscillation from the detected time history of the current flowing through the coil drive current, and (d) determining a time to which an amplitude change takes place in the case of the extracted current oscillation, the specific time being the ^{instant of the predefined} operating state.

The method described is based on the finding that the resonant frequency of a resonant circuit containing the coil drive changes with movement of the coil drive, then the current intensity (amplitude) of an alternating current component (current oscillation), which flows through the coil drive due to an alternating voltage superimposed on the drive voltage, also changes accordingly. By evaluating the current flowing through the coil drive current thus different operating conditions can be detected, which are associated with movements in the coil drive.

In this document, "drive voltage" refers in particular to a voltage curve with which the coil drive is driven in operation.

When the coil drive is acted upon by the predetermined drive voltage, at least part of the drive voltage is superposed with an alternating voltage, that is, during at least part of the application, the drive voltage is superimposed with the alternating voltage. The superimposed alternating voltage causes an additional alternating current (current oscillation), which has the same frequency as the alternating voltage, to flow through the coil drive. The amplitude of the superimposed alternating voltage is preferably selected to be so small in comparison with the drive voltage that the current oscillation caused by the superimposed alternating voltage has no recognizable influence on the mechanical behavior of the spool drive. Consequently, the coil drive ever ^¬ neuter operates in response to the applied drive voltage.

The current (amplitude) of this alternating current depends on the ratio between the frequency of the AC voltage and the current resonant frequency of the resonant circuit. With a change in the resonant frequency of the resonant circuit consequently also a corresponding change in the amplitude of the current oscillation. Takes place by determining a time at which a Amplitu ^¬ denänderung in the extracted current oscillation, thus a time is determined which a particular loading corresponds to drive state, in which the inductance of the coil drive has a certain value.

Thus, for example, in connection with an electromagnetically driven injection valve, such operating states as opening time (OPP1), reaching the full control ^¬ (OPP2), beginning of the closing phase (OPP3) and

Closing time (OPP4) are determined. According to one embodiment of the invention is the

Oscillating circuit a parallel resonant circuit, which has the inductance and resistance of the coil drive in parallel with a capacity. In this document, "capacity" means, in particular, an electrical capacity.

The capacity may as an output capacitance of a clamping ^¬ voltage supply, as a capacity be implemented in cables or on a circuit board or as a specifically mounted capacitor. The capacity may also be implemented as a combination of several of the elements just mentioned.

In addition to the electrical resistance of the coil drive, the resonant circuit may also have other resistors, such as an output resistance of a voltage supply.

The resonant circuit forms a parallel resonant circuit in the sense that it consists essentially of a capacitance, a resistor and an inductance, all of which are connected in parallel.

According to a further embodiment of the invention, the frequency of the AC voltage is equal to a resonant frequency of the resonant circuit.

The resonant frequency of the resonant circuit basically depends on the inductance of the coil drive and thus changes with changes in the inductance of the coil drive. This one The aforementioned resonant frequency of the resonant circuit may preferably correspond to a certain state of the coil drive, such as a closed state without Bewegungsinduktivität.

The amplitude of the current oscillation is minimal as long as the resonance frequency is equal to the frequency of the AC voltage. When the resonance frequency changes, the amplitude of the current vibration increases and the corresponding time is determined.

Exemplary values for the resonance frequency are generally in the range between 50 kHz and 1 MHz, in particular between 100 kHz and 800 kHz, in particular between 200 kHz and 600 kHz, in particular between 300 kHz and 400 kHz. In particular at higher frequencies EMC-technical restrictions must be observed. If necessary, remedial action must be taken by appropriate measures (e.g., shielding, etc.). According to a further embodiment of the invention, the extraction comprises a high-pass filtering of the detected time profile of the current intensity of the current flowing through the coil drive current. By high-pass filtering of the detected time course of the current strength, the current oscillation can be extracted in a simple and efficient manner from the current flowing as a result of the applied drive voltage in the coil drive current.

According to another embodiment of the invention, determining the time comprises comparing the amplitude of the current swing with a predetermined threshold. This may for example be implemented so that a timing is determined when the amplitude exceeds the predetermined smoldering ^¬ lenwert. Alternatively, a time may be determined when the amplitude falls below the predetermined threshold.

According to another embodiment of the invention, determining the time comprises comparing the extracted current swing with a reference swing.

The reference vibration may speak in particular a state ^¬ ent, in which the bobbin drive is held during Beaufschlagens with the predetermined driving voltage, so that the resonant frequency of the resonant circuit does not change.

The comparison of the extracted current oscillation with the reference oscillation may take place in particular by subtraction. A time is then determined when the difference between current oscillation and reference oscillation a

Exceeds threshold.

According to a second aspect of the invention an apparatus for determining the timing of a predetermined operation ^¬ state of a coil drive is having ^¬ electromag netic driven apparatus, in particular an injector for fuel injection described. The described device comprises: (a) a unit for acting on the coil drive with a predetermined drive voltage, wherein at least a part of the drive voltage with a

Superimposed on alternating voltage, which is used to excite a

Tuning circuit is adapted, which contains the coil drive,

(b) a unit for detecting the time course of the current of a current flowing through the coil drive,

(c) a unit for extracting one of the superimposed ones

AC voltage corresponding current oscillation from the detected time course of the current flowing through the coil drive current, and (d) a unit for determining a time at which in the extracted

Current vibration takes place an amplitude change, wherein the specific time is the time of the predetermined Be ^¬ drive state. The device according to the second aspect is based essentially on the same knowledge described above in connection with the first aspect.

The apparatus according to the second aspect is particularly capable of performing the method according to the first aspect or one of the above embodiments.

According to a third aspect of the invention, an engine control system for a motor vehicle is set up, which is set up to carry out the method according to the first aspect and / or one of the above exemplary embodiments.

This engine control makes it possible to simply, simply, accurately and efficiently determine different operating states of a fuel injector, and thus to adapt and optimize the control based on the specific operating conditions.

According to a fourth aspect of the invention, a computer program is described which, when executed by a processor, is adapted to perform the method according to the first aspect and / or one of the above embodiments.

For the purposes of this document is the mention of such Com ^¬ computer program equivalent to the concept of a Pro ^¬ program element, a computer program product and / or a computer-readable medium containing instructions for controlling a computer system to the operation of a system or a method in to coordinate suitably to achieve the effects associated with the method according to the invention.

The computer program may be implemented as a computer-readable instruction code in any suitable programming language such as JAVA, C ++, etc. The computer program can be stored on a computer-readable storage medium (CD-ROM, DVD, Blu-ray Disc, Removable drive, volatile or non-volatile memory, built-in memory / processor, etc.) to be stored. The instruction code may program a computer or other programmable device, such as, in particular, an engine control unit of a motor vehicle, such that the desired

Functions are performed. Further, the computer program may be provided in a network, such as the Internet, from where it may be downloaded by a user as needed.

The invention can be implemented both by means of a computer program, i. software, as well as by means of one or more special electrical circuits, i. in hardware or in any hybrid form, i. using software components and hardware components.

It should be noted that embodiments of the invention have been described with reference to different subject ^{matters ¬} . In particular, some embodiments of the invention are described with method claims and other embodiments of the invention with apparatus claims. However, it will be apparent to those skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features associated with a type of subject invention, any combination of features may be used that are different Types of inventions include.

Further advantages and features of the present invention will become apparent from the following exemplary description of a preferred embodiment.

FIG. 1A shows a parallel resonant ^circuit according to an ^exemplary embodiment.

FIG. 1B shows an equivalent circuit diagram for the parallel resonant circuit shown in FIG. 1A. FIG. 2 shows the currents in the parallel resonant circuit shown in FIG. 1B as functions of the frequency.

FIG. 3A shows a time profile of a drive voltage with superimposed AC voltage according to one exemplary embodiment.

FIG. 3B shows a time profile of a current intensity of a current flowing through a coil drive according to an exemplary embodiment.

3C shows needle lift and armature stroke for a fuel injector ^¬ controlled at ^¬ according to an embodiment.

FIG. 4 shows an amplitude change in a current oscillation in accordance with one exemplary embodiment.

It should be noted that the embodiment described below represents only a limited selection of possible embodiments of the invention.

FIG. 1A shows a parallel resonant ^circuit 1 according to an ^exemplary embodiment. The parallel resonant circuit 1 is composed of a series circuit of a coil resistance R _L and an SPU leninduktivität ^¬ L in parallel with a capacitor C and a resistor R _P _Cp.

FIG. 1B shows an equivalent circuit diagram 2 for the parallel resonant circuit 1 shown in FIG. 1A. The equivalent circuit diagram 2 has only one parallel circuit of capacitance C, resistor R and inductance L.

The total impedance of circuit 2 is:

The resonant frequency of the circuit 2 is:

2 * n * jLC If an alternating voltage with the frequency calculated from formula (II) is applied to the resonant circuit 2, the values of both reactances are the same and thus cancel each other out. This means that only the purely ohmic resistance acts to the outside. The supplied current Io is minimal at resonance, the currents through capacitance C and coil L may be larger, as shown in FIG.

FIG. 2 shows in particular the supplied current Io 3, the current 4 through the capacitance C and the current 5 through the inductance 5, all as functions of the frequency. A parallel resonant circuit is characterized by resonance due to current increase at L and C.

Figures 3A to 3C show voltage, current, needle and armature stroke when operating a fuel injector according to the present invention.

For the detection of an operating state (e.g., OPP1 / 2, OPP3 / 4) of the fuel injector, the driving voltage 6 is applied with an AC voltage 7 as a high-frequency excitation for the

Resonant circuit superimposed. Depending on the location of the detected

Event, the modulated sine voltage can be fed in different phases of the control. In this example, the AC voltage 7 during the boost phase (in which the drive voltage is increased to the so-called boost voltage U) is turned on to detect OPP1 / 2.

This AC voltage 7 is fed with the resonant frequency of the resonant circuit 2. In the current, the ^superimposed voltage 7, as shown in FIG. 3B, causes a current oscillation 9 during the boost phase, that is to say while the current increases up to the peak value I _p (peak current). The curve 8 shows the current profile when the drive voltage 6 is used without superimposed AC voltage.

As a result of the movement of the armature or the needle of the fuel injector, the differential inductance in the magnetic circuit changes. This has the consequence that the resonant frequency of the resonant circuit 2 changes. Since the frequency of the exciting voltage does not change, the resonant circuit 2 is no longer operated in resonance and thus, according to FIG. 2, there is a direct reaction to the currents. This results in an amplitude change in the current oscillation 9, which is marked with an arrow 10 in FIG. 3B. As can be seen in FIG. 3C, the amplitude change takes place at the point in time when the needle stroke 11 and the armature stroke 12 become greater than zero.

This change in the behavior of the resonant circuit 2 and thus the time of opening of the fuel injector can thus be detected by observing the current 9. The current 9 is measured by the engine control unit during activation of the injector. By means of filtering (high-pass filtering), the current oscillation generated by the modulated voltage is extracted and evaluated with regard to its maximum amplitude.

This is shown in FIG. 4, which shows an extracted current oscillation 13. Increases the difference between the amplitude in the ΔΙ Re ^¬ sonanzfall i _res and the current amplitude Ϊ over a specified limit, the date is stored. By suitable design of the system and the limit, this time OPP1 / 2/3/4 can be assigned.

Another possibility is to store a reference curve of the current curve in the motor control. Preferably, one uses the measurement of the current (with the above-described control) of a blocked injector. There is thus no movement during the control of the injector and thus no reaction to the current (resonant circuit 2 is always in resonance). If one then compares the current oscillation of an unblocked injector with the stored reference, it can again evaluating the amplitude difference, an operating state can be detected.

Reference sign list

1 parallel swinging circle

2 equivalent circuit diagram

3 current curve

4 current curve

5 current curve

6 drive voltage

7 alternating voltage

8 electricity

9 electricity

10 arrow

11 needle stroke

12 anchor stroke

13 electricity

Claims

claims

1. A method for determining the time of a vorbe ^¬ certain operating condition of a coil drive aufwei- sending electromagnetically driven device, in particular an injector for fuel injection, the method comprising

Acting on the coil drive with a predetermined drive voltage, wherein at least a part of the drive voltage is superimposed with an alternating voltage, which is adapted to excite a resonant circuit, which contains the coil drive,

Detecting the time profile of the current intensity of a current flowing through the coil drive current,

Extracting one of the superimposed AC voltage corresponding current vibration from the detected temporal

The course of the current flowing through the coil drive current, and

Determining a time at which an amplitude change takes place in the extracted current oscillation, wherein the specific time is the time of the predetermined Be ^¬ drive state.

2. The method of claim 1, wherein the resonant circuit is a parallel resonant circuit having the inductance and resistance of the coil drive in parallel with a capacitance.

3. The method according to any one of the preceding claims, wherein the frequency of the AC voltage is equal to a resonant frequency of the resonant circuit.

4. The method of claim 1, wherein the extracting comprises a high-pass filtering of the detected time profile of the current intensity of the current flowing through the coil drive.

5. The method of claim 1, wherein determining the time comprises comparing the amplitude of the current swing to a predetermined threshold.

6. The method of claim 1, wherein determining the time comprises comparing the extracted current swing to a reference swing.

7. An apparatus for determining the time of a vorbe ^¬ certain operating condition of a coil drive aufwei ^¬ send electromagnetically driven device, in particular an injector for fuel injection, comprising the device

a unit for actuating the coil drive with a predetermined drive voltage, wherein at least a part of the drive voltage is superimposed with an alternating voltage, which is adapted to excite a resonant circuit, which contains the coil drive,

a unit for detecting the time profile of the current intensity of a current flowing through the coil drive, a unit for extracting a current oscillation corresponding to the superimposed alternating voltage from the recorded time curve of the current intensity of the current flowing through the coil drive, and

a unit for determining a point in time at which an amplitude change takes place in the extracted current oscillation, wherein the specific time is the time of the ^predefined operating state.

8. Motor control for a motor vehicle, which is adapted to carry out the method according to one of claims 1 to 6.

A computer program which, when executed by a processor, is adapted to perform the method of any one of claims 1 to 6.