EP2340544B1 - Method for detecting the position of an armature of an electromagnetic actuator - Google Patents

Description

The present invention relates to a method for position detection of the magnet armature of an electromagnetic actuator displaceably arranged between two coils according to the preamble of patent claim 1.

In such actuators with two coils is known to detect the position of the magnet armature slidably disposed between the coils without the need for an additional sensor. For this purpose, both coils are connected in series and there is a voltage jump on the arrangement, whereby the two coils form a voltage divider according to the known from measuring technology reactor coil principle. From the difference between the two voltages generated, the position of the armature can be determined. For example, if the armature is in the first coil, the voltage in the first coil at the beginning of the step response will be greater than the voltage in the second coil; from the ratio of the voltages to the magnet hub, a position-dependent path signal can be generated in a simple manner.

For example, is from the DE 10 2005018012 A1 the Applicant an electromagnetic actuator and a method for driving the actuator known, wherein the actuator consists of an armature and two coils. As part of the DE 10 2005018012 A1 It is proposed to measure the voltage curve at the two coils during a suddenly increasing energization, wherein a third voltage profile is calculated from these measured data in a subtractor, from which a logic unit, the position of the armature slidably mounted between the coils is determined without the use of an additional sensor ,

However, the path signal generated in this way depends strongly on the height and the course of the voltage jump, which is neither constant nor has the same value in practice due to line losses or deviations of the vehicle electrical system voltage. Furthermore, the measured value is detrimentally falsified as the value for the timing of the detection after the voltage jump of temperature effects due to the ohmic component and magnetic saturation effects increases.

From the DE19748647 C2 is known an electromagnetic drive system with integrated displacement signal generation, comprising an electric motor, comprising a first subsystem with at least one permanent magnet and a second subsystem with a coil system, comprising at least two identical, successively arranged partial coils. In the known system, each subsystem forms the stator or the movable rotor; Furthermore, a drive circuit is provided, which serves to generate a pulse width modulated control voltage with a constant pulse frequency and a constant switching voltage in the coil system. The known system comprises an evaluation circuit which, by separately differentiating the voltage profiles over the partial coils and then subtracting or dividing the resulting new differentiated partial voltages at a constant time after the edge change in the pulse-width-modulated actuating signal a weg- or angle-proportional voltage value for the relative position between the derives first subsystem of the engine and the second subsystem. The conception of the dual use of the drive windings eliminates the need for separate measuring systems for determining the position of the moving relative to the stationary subsystem of the drive system.

The present invention is based on the object, starting from the known prior art according to the DE 10 2005018012 A1 the Applicant a method for position detection of displaceable between two coils to provide arranged magnet armature of an electromagnetic actuator, by the implementation of a voltage independence of the measurement signal for the position of the armature is achieved.

This object is solved by the features of patent claim 1. Further embodiments and advantages of the invention will become apparent from the dependent claims.

Accordingly, a method for detecting the position of the magnet armature of an electromagnetic actuator displaceably arranged between two coils is proposed, in the context of which the arrangement is suddenly energized by means of a voltage jump and the voltage profile at the two coils is measured, wherein from these measured data for the voltage curve at both coils calculated voltage level to the height of the voltage jump, which is independent of voltage fluctuations.

According to the invention, the quotient of the difference between the two voltage values and the voltage jump, which is normalized to the magnitude of the voltage jump, is calculated from the measured data for the voltage profile at a specific point in time on both coils of the electromagnetic actuator.

In this case, according to the invention, each value of the quotient formed is assigned a specific armature stroke, whereby this unambiguous assignment can be determined by calculation, by means of a simulation or by means of tests.

The assignment of the armature stroke to the values of the quotient formed according to the invention is stored in the controller as a characteristic curve or as a function of the measurement time as a characteristic field.

According to an advantageous embodiment of the invention, it is proposed to carry out the measurement of the voltages on both coils at the time after the energization of the actuator, at which the gradient of the voltage curve of the voltages at both coils assumes the value zero, i. where the tensions of the voltages reach the vertex; due to the characteristics of the system, the peak of the voltage waveforms on both coils is reached at the same time.

This avoids unwanted temperature effects as well as magnetic saturation effects that occur when the measurement time of the voltages on both coils is greater than the time of reaching the vertex.

Figur 1:

Ein vereinfacht dargestelltes Prinzipschaubild eines elektromagnetischen Aktuators umfassend einen zwischen zwei Spulen verschiebbar angeordneten Magnetanker; und

Figur 2:

Ein Diagramm, welches die Verläufe der Spannungen an den beiden Spulen des elektromagnetischen Aktuators nach dem Anlegen eines Spannungssprunges und den Verlauf des Stromes nach dem Anlegen eines Spannungssprunges als Funktion der Zeit darstellt.

The invention will be explained in more detail below with reference to the accompanying figures by way of example. Show it:

FIG. 1:

A simplified illustrated schematic diagram of an electromagnetic actuator comprising a slidably disposed between two coils armature; and

FIG. 2:

A diagram showing the curves of the voltages on the two coils of the electromagnetic actuator after the application of a voltage jump and the course of the current after the application of a voltage jump as a function of time.

In FIG. 1 is a simplified illustrated schematic diagram of an electromagnetic actuator comprising a slidably disposed between two coils magnet armature shown. Here, the first coil of the actuator with 1, the second coil with 2 and the armature is denoted by 3. The The ohmic resistors associated with the coils are designated 4 and 5, respectively.

According to the invention and with reference to the upper part of FIG. 2 For the position detection of the magnet armature 3 displaceably arranged between the coils 1, 2, a voltage jump U _{B is} applied to the series-connected coils 1, 2 of the actuator, whereby the two coils 1, 2 form a voltage divider according to the choke coil principle known from measurement technology. The voltage U ₁ at the first coil 1 and the voltage U ₂ at the second coil 2 are preferably measured according to the invention at a predetermined time t_meas, from these measured data the normalized to the height of the voltage jump U _B quotient of the difference .DELTA.U between both voltage values and the voltage jump U _{B is} calculated. The corresponding formula is: $$\mathrm{\Delta }U/U_B=\frac{U_1-U_2}{{\mathrm{<figure-callout\; id="1"\; label="U"\; filenames="imgf0001.png"\; state="\{\{state\}\}">U</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="imgf0001.png"\; state="\{\{state\}\}">U</figure-callout>}}_2}\mathrm{,}$$

In this case, a specific armature stroke is assigned to each value of the quotient formed according to the invention at each point in time t_meas, wherein this unambiguous assignment can be determined by calculation, by means of a simulation or by means of tests and stored in the control as a characteristic curve.

It is particularly advantageous if the measurement of the voltages U ₁ and U _{2 is carried out} after the application of the voltage jump at the time at which the gradient of the voltage curve of the voltages at both coils assumes the value zero; this time corresponds to the upper part of the FIG. 2 shown time t_Mess; In this figure, the vertex of the voltage waveforms on both coils 1, 2 is designated A. In the lower part of the FIG. 2 the course of the current after the application of the voltage jump U _{B is shown} as a function of the time t.

The inventive concept results in the advantage that the characteristic curve generated is independent of operating voltage fluctuations. In addition, the definition of the optimum measuring time largely avoids temperature effects or magnetic saturation effects.

reference numeral

1

Kitchen sink

2

Kitchen sink

3

armature

4

ohmic resistance

5

ohmic resistance

UB

voltage jump

U1

Voltage on the coil 1

U2

Voltage on the coil 2

t_Mess

Measuring time

l

electricity

t

Time

A

vertex

Claims (4)

1. Method for detecting the position of the magnet armature (3) of an electromagnetic actuator, the said magnet armature being arranged in a movable manner between two coils (1, 2), with a voltage jump U_B being applied to the coils (1, 2) of the actuator, the said coils being connected in series, as a result of which the two coils (1, 2) form a voltage divider in line with the induction coil principle, and with the voltage U₁ being measured across the first coil (1) and the voltage U₂ being measured across the second coil (2), characterized in that the measurement data for the voltages across the coils (1, 2) is used to calculate the quotient, which is standardized at the level of the voltage jump U_B, from the difference ΔU between the two voltage values and the voltage jump U_B, with each value of the quotient having a uniquely associated apecific armature stroke.
2. Method for detecting the position of the magnet armature (3) of an electromagnetic actuator, the said magnet armature being arranged in a movable manner between two coils (1, 2), according to Claim 1, characterized in that the unique association of the values of the quotient with the armature stroke is determined by calculation, by means of a simulation or by means of experiments.
3. Method for detecting the position of the magnet armature (3) of an electromagnetic actuator, the said magnet armature being arranged in a movable manner between two coils (1, 2), according to Claim 2, characterized in that the association of the values of the quotient with the armature stroke is stored in the control means as a characteristic curve or, as a function of the measurement time, as a characteristic map.
4. Method for detecting the position of the magnet armature (3) of an electromagnetic actuator, the said magnet armature being arranged in a movable manner between two coils (1, 2), according to Claim 1, 2 or 3, characterized in that the measurement of the voltages across the two coils (1, 2) is carried out at the time t_measure after the voltage jump U_B is applied at which the gradient of the voltage profile of the voltages across the two coils (1, 2) assumes the value zero.

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