Methods for position detection, methods for valve control and fluid valve

Abstract

Method for detecting the position (50) of a linear position (P) of an electromagnet (33) associated with a fluid valve (10), the electromagnet having at least one electrically operable coil (34) with an actuating voltage and a magnetic core (36) mounted so as to be translationally movable relative to the coil (34), which is movable by changing the linear position (P) depending on a coil current of the coil (34) built up by the actuating voltage, wherein the linear position (P) is detected by measuring the actuating voltage and the coil current and depending on the measured actuating voltage (U) m ) and the measured coil current (I m ) the linear position (P) is calculated, wherein the magnetic core (36) is movable against the spring force (42) of a spring element (44) while changing the linear position (P) and the linear position (P) of the magnetic core (36) acted upon by the spring force (42) is detected by the actuation voltage is applied as an alternating voltage to the coil (34), which causes an alternating current as coil current in the coil (34), the actuation voltage and the coil current are measured, from the measured actuation voltage (U m ) and the measured coil current (I m ) at least one voltage parameter (P u ) and a current parameter (P i ) are recorded and from the voltage parameter (P u ) and the current parameter (P i ) a complex AC resistance (Z) of the coil (34) is calculated and the linear position (P) is calculated as a function of the AC resistance (Z), characterized in that the voltage parameters (P u ) and current parameters (P i ) by a singular value decomposition or principal component analysis of a correlation matrix (A) consisting of a normalized voltage (U) n,m ) the measured actuation voltage (U m) and a normalized current (I n,m ) of the measured coil current (I m ) has calculated components, will be calculated.

Description

[0001] The invention relates to a method for position detection according to the preamble of claim 1. Furthermore, the invention relates to a method for valve control and a fluid valve.

[0002] DE 10 2014 016 189 A1 discloses the determination of a position of a movable element of a linear actuator intended for a motor vehicle.

[0003] DE 10 2008 042 095 A1 discloses a method for operating an electromagnetic actuator.

[0004] DE 10 2021 201 003 A1 discloses a method and a circuit arrangement for determining the position of a magnetic armature within a coil.

[0005] CN 1 12 146 555 A describes a method for detecting the position of a solenoid valve. The position is detected by measuring a valve voltage and the resulting coil current of a solenoid coil, and by detecting any change in the coil current. From the current change and the measured valve voltage, a coil inductance is calculated, which is then used to determine the position.

[0006] The object of the present invention is to detect the linear position of a fluid valve more accurately and cost-effectively. The fluid valve should then be operated more accurately and cost-effectively.

[0007] At least one of these tasks is solved by a position detection method with the features of claim 1. This allows the linear position of the fluid valve to be detected more accurately and cost-effectively. A position sensor for position detection can be omitted.

[0008] The position detection method can be used in a vehicle. The vehicle can be a motor vehicle. The position detection method can be performed while the vehicle is in motion.

[0009] The fluid valve can be a proportional valve that continuously changes the linear positions.

[0010] The coil can have multiple turns. The magnetic core can also be called the armature.

[0011] The spring element can be a helical spring. The spring force can be aligned parallel to the direction of movement of the magnetic core.

[0012] Alternating voltage is a harmonic oscillation with a predetermined frequency. Alternating current is a harmonic oscillation of the same frequency, possibly with a phase difference compared to the alternating voltage.

[0013] The operating voltage can have a constant voltage component and an alternating voltage component, and the coil current can have a constant current component and an alternating current component. The alternating voltage component U a The so-called dither voltage has the advantage of reducing the static friction of the magnetic core. The alternating current component I a can exhibit an alternating current amplitude of a few mA. The alternating current amplitude is preferably smaller than the constant current component I. d .

[0014] In a specific embodiment of the invention, it is advantageous to capture a constant voltage component and / or an alternating voltage component of the actuation voltage as voltage parameters. These voltage parameters can be further processed to calculate the complex AC resistance or used directly.

[0015] A preferred embodiment of the invention is advantageous in which a constant current component and / or an alternating current component of the coil current are recorded as current parameters. The current parameters can be further processed to calculate the complex AC resistance or used directly.

[0016] In a preferred embodiment of the invention, it is provided that the magnetic core assumes a first linear position when the coil current is absent and a second linear position when the coil current is applied, against the spring force, and the linear position to be detected is an intermediate linear position lying between the first and second linear positions, in which the magnetic core is acted upon by the spring force.

[0017] The first linear position can be a first maximum linear position. The second linear position can be the opposite second maximum linear position. In the first linear position, the magnetic core can be subjected to spring force. The magnetic core can be subjected to spring force in all linear positions.

[0018] Some of the linear positions may lie within an approximately linear curve of the spring element's characteristic. Therefore, the coil current could be used as a measure of the linear position. However, it has been recognized that this relationship is only valid for very high spring stiffnesses and is often not applicable in practice.

[0019] In a preferred embodiment of the invention, the complex AC resistance is calculated as Z = X R + iX L composed of these elements, resulting in an effective resistance R as the real AC resistance X Rand an inductance L from the imaginary AC resistance X L with L=XL2πf The linear position can be calculated as a function of the resistance R and the inductance L. If the resistance R and the inductance L are sufficiently known, the linear position can be uniquely calculated.

[0020] In a preferred embodiment of the invention, it is advantageous if the linear position is calculated using a lookup table as a function of the resistance R and the inductance L. The lookup table can map the linear position for different values ​​of resistance and for different values ​​of inductance in combination.

[0021] In a preferred embodiment of the invention, it is advantageous if the measured actuation voltage is expressed as a complex voltage U. c and the measured coil current as complex current I ctransformed and the complex AC resistance with Z=UcIc is calculated. From the complex AC resistance Z, the active resistance R and the imaginary AC resistance X can be determined. L and from this the inductance L can be calculated. The linear position can then be calculated using a lookup table. The complex voltage U c and the complex current I c can be calculated as follows: First, the following voltage and current parameters are calculated from the measured operating voltage and the measured coil current:

[0022] An offset voltage Uo=max(Um)+min(Um)2

[0023] A voltage amplitude Ua=max(Um)−min(Um)2

[0024] An offset current Io=max(Im)+min(Im)2

[0025] A current amplitude Ia=max(Im)−min(Im)2

[0026] This results in a normalized voltage. Un=Um−UoUa and a standardized current In=Im−IoIa calculated. A transformed voltage is calculated using the normalized voltage and current. U=Un−In and a transformed current Ir=Un+In The voltage amplitude of the transformed voltage and the current amplitude of the transformed current are calculated together as a complex representation, with the voltage amplitude of the transformed voltage being the same. Us=max(Ur)−min(Ur)2 as the real part and the current amplitude of the transformed current Is=i⋅max(Ir)−min(Ir)2 as an imaginary part. This makes the complex tension into Uc=(−Us+Is)⋅Ua and the complex flow to Ic=(Us+Is)⋅Ia

[0027] According to the invention, the voltage parameters and current parameters are determined by a singular value decomposition or principal component analysis of a correlation matrix A, which consists of a normalized voltage U. n the measured actuation voltage and a normalized current I n The components calculated from the measured coil current can be calculated. Starting from the offset voltage Uo=max(Um)+min(Um)2 and the offset current Io=max(Im)+min(Im)2 can a standardized voltage Un,m=Um−Uo and a standardized current In,m=Im−Io can be calculated. From this, a symmetric correlation matrix A can be calculated as follows. A=[Un,mT⋅Un,mUn,mT⋅In,mUn,mT⋅In,mIn,mT⋅In,m]

[0028] Using singular value decomposition or principal component analysis, the eigenvector matrix W and eigenvalue matrix λ of A are calculated.

[0029] Thus, assuming |X| > 1, the complex voltage becomes Uc=W(1,1)⋅λ(1,1)−i⋅W(2,1)⋅λ(2,2) and the complex flow to Ic=W(2,1)⋅λ(1,1)−i⋅W(2,2)⋅λ(2,2) and for |X| ≤ 1 Ic=W(1,1)⋅λ(1,1)−i⋅W(2,1)⋅λ(2,2) Uc=W(2,1)⋅λ(1,1)−i⋅W(2,2)⋅λ(2,2) calculated. From these transformed voltage and current parameters, the complex AC resistance can be calculated using Z=UcIc can be calculated. From the complex AC resistance Z, the active resistance R and the imaginary AC resistance X can be determined. L and the inductance L can be calculated from this. The linear position can then be calculated using a lookup table.

[0030] Furthermore, within the scope of the invention, a method for valve control with the features of claim 8 is proposed to solve at least one of the aforementioned problems. This allows the fluid pressure and / or fluid volume flow to be adjusted more precisely.

[0031] Furthermore, within the scope of the invention, a fluid valve with the features of claim 9 is proposed to solve at least one of the aforementioned problems. The valve piston can have several control edges that influence the fluid pressure and / or fluid volume flow rate depending on the linear position and thus the position of the control edges in relation to the fluid channels of the fluid valve.

[0032] The fluid valve can be a hydraulic valve. The fluid flow rate can be a hydraulic fluid flow. The fluid pressure can actuate a vehicle component. The fluid flow rate can cool a vehicle component. The vehicle component can be a clutch, parking lock, or drive motor.

[0033] The spring element can be arranged on the side of the fluid valve facing away from the electromagnet.

[0034] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations. Character description

[0035] The invention is described in detail below with reference to the illustrations. These show, in detail: Fig. 1: A functional circuit diagram of a fluid valve in a special embodiment of the invention. Fig. 2: A cross-section of a fluid valve in a further special embodiment of the invention. Fig. 3: A dependence of a complex AC resistance on a linear position. Fig. 4: A measured operating voltage and a measured coil current. Fig. 5: A method for position detection and a method for valve control, each in a specific embodiment of the invention. Fig. 6: A method for position detection in a further special embodiment of the invention. Fig. 7: A method for position detection in a further special embodiment of the invention. Fig. 8: An inaccuracy in the comparison of the different methods of position detection.

[0036] Fig. Figure 1 shows a functional circuit diagram of a fluid valve in a specific embodiment of the invention. The fluid valve 10 is designed as a 4 / 3-way valve and comprises an actuating part 12 and a hydraulic part 14 mechanically connected to it. A first fluid channel 16, which is connected to a fluid pump, and a second fluid channel 18, which is connected to a fluid accumulator as a return, are connected to the hydraulic part 14. An opposing third fluid channel 20 is connected to a vehicle component, for example, a parking lock device, for transmitting fluid pressure and thus for actuation, and a fourth fluid channel 22 is connected to another vehicle component, for example, a clutch, for transmitting fluid pressure and thus for actuation.

[0037] The fluid valve 10 can assume a first valve state 24 in which the third fluid channel 20 is connected to the second fluid channel 18 for pressure relief, and the first fluid channel 16 is connected to the fourth fluid channel 22 for transmitting fluid pressure to the clutch. A second valve state 26 blocks the connections between the first and third fluid channels 16, 20 and the second and fourth fluid channels 18, 22. A third valve state 28 connects the first fluid channel 16 to the third fluid channel 20 for transmitting fluid pressure to actuate the parking lock and the second fluid channel 18 to the fourth fluid channel 22 for pressure relief.

[0038] Fig. Figure 2 shows a cross-section of a fluid valve in a further specific embodiment of the invention. The fluid valve 10 comprises the actuating part 12 and the hydraulic part 14 mechanically connected thereto. The hydraulic part 14 comprises a valve piston 30 for adjusting a fluid flow rate through the fluid valve 10. The valve piston 30 has several control edges 31 for adjusting the fluid pressure or fluid flow rate in the connected fluid channels 32.

[0039] The actuating element 12 comprises an electromagnet 33 with an electrically operable coil 34 and a magnetic core 36, which is mounted translationally movable relative to the coil 34 and is movable by changing a linear position P depending on a coil current in the coil 34 generated by the actuating voltage. The magnetic core 36 is slidably coupled to the valve piston 30. The magnetic core 36 can assume a first linear position P1, in particular a first maximum linear position, and an opposite second linear position P2, in particular a second maximum linear position, as well as intermediate linear positions Pn.

[0040] The magnetic core 36 is movable against a spring force 42 of a spring element 44 in a first direction of movement 46 and, supported by the spring force 42, in an opposite second direction of movement 48. When the coil current is absent, the magnetic core 36, supported by the spring force 42, assumes the first linear position P1.

[0041] Fig. Figure 3 shows the dependence of the AC resistance on the linear position. With increasing linear position P, the complex AC resistance exhibits an increasing real AC resistance, corresponding to an increasing resistance R, and an increasing imaginary AC resistance, corresponding to an increasing inductance L. If the complex AC resistance is known, i.e., if the resistance R and the inductance L can be calculated, then the linear position P can be determined.

[0042] Fig. Figure 4 shows a measured actuation voltage and a measured coil current. The in Fig. 4 a) shown measured actuation voltage U m exhibits a constant voltage component U d and an alternating voltage component U a on. Also the one in Fig. 4 b) shown measured coil current I m exhibits a constant current component I d and an alternating current component I a on. The alternating voltage component U c and the alternating current component I a They change harmonically with a frequency f of 100 Hz. The constant current component I d Here, the current is 1 A and the alternating current component is I a a few mA, so it's much smaller.

[0043] Fig. Figure 5 shows a method for position detection and a method for valve control, each in a specific embodiment of the invention. The method for position detection 50 enables the measurement of various linear positions P of the magnetic core acted upon by the spring force, while the actuation voltage is applied to the coil as an alternating voltage, which causes the coil current to be an alternating current.

[0044] First, the actuation voltage and the coil current are measured. From the measured actuation voltage U m and the measured coil current I m At least one voltage parameter P will be u and a current parameter P i recorded. In particular, the constant voltage component U is recorded. d and the alternating voltage component U a the measured actuation voltage U m as well as the constant current component I d and the alternating current component I a of the measured coil current I mThe data is recorded. From this, the complex AC resistance is calculated. The real AC resistance is an active resistance R, which is calculated using... R=UdId

[0045] The imaginary AC resistance X L is XL=Ua2−(R⋅Ia)2Ia with the frequency f of the alternating voltage. Subsequently, the linear position P depends on the resistance R and the imaginary AC resistance X as follows. L calculated inductance L=XL2πf calculated using a lookup table 52. This procedure for determining the linear position P is preferred when the imaginary AC resistance X L much smaller than the resistance R.

[0046] Furthermore, a method for controlling the fluid valve 54 is shown, which moves the magnetic core to set a fluid pressure 55 and / or fluid volume flow rate 56 depending on a linear position P of the electromagnet detected by the previously described method for position detection 50.

[0047] Fig. Figure 6 shows a method for position detection in a further specific embodiment of the invention. Given an existing linear position P of the magnetic core, which is acted upon by the spring force, the determination of the linear position P is carried out starting with the measurement of the actuation voltage and the coil current. From the measured actuation voltage U m and the measured coil current I m The following voltage parameters P u and current parameter P i recorded:

[0048] An offset voltage Uo=max(Um)+min(Um)2

[0049] A voltage amplitude Ua=max(Um)−min(Um)2

[0050] An offset current Io=max(Im)+min(Im)2

[0051] A current amplitude Ia=max(Im)−min(Im)2

[0052] This results in a normalized voltage. Un=Um−UoUa and a standardized current In=Im−IoIa calculated. With the normalized voltage U n and the standardized current I n A transformed voltage will be used Ur=Un−In and a transformed current Ir=Un+In calculated. The voltage amplitude of the transformed voltage U c and the current amplitude of the transformed current I r are considered together as a complex representation, with the voltage amplitude of the transformed voltage Us=max(Ur)−min(Ur)2 as the real part and the current amplitude of the transformed current Is=i⋅max(Ir)−min(Ir)2 as an imaginary part. This makes the complex tension into Uc=(−Us+Is)⋅Ua and the complex flow to Ic=(Us+Is)⋅Ia

[0053] From these transformed stress parameters P u and current parameters P i can the complex AC resistance Z be calculated using Z=UcIc They can be calculated. The active resistance R and the imaginary AC resistance X are derived from the complex AC resistance Z. L and from that the inductance L=XL2πf calculated, whereby the linear position P is calculated using a lookup table 52.

[0054] Fig. Figure 7 shows a method for position detection in a further specific embodiment of the invention. Given an existing linear position P of the magnetic core, which is acted upon by the spring force, the determination of the linear position P is carried out starting with the measurement of the actuating voltage and the coil current. From the measured actuating voltage U m and the measured coil current I m The following voltage parameters P u and current parameter P i recorded:

[0055] An offset voltage Uo=max(Um)+min(Um)2 and an offset current Io=max(Im)+min(Im)2.

[0056] This results in a normalized voltage. Un,m=Um−Uo and a standardized current In,m=Im−Io calculated. From this, a symmetric correlation matrix A is calculated as follows. A=[Un,mT⋅Un,mUn,mT⋅In,mUn,mT⋅In,mIn,mT⋅In,m]

[0057] Using singular value decomposition or principal component analysis, the eigenvector matrix W and eigenvalue matrix λ of A are calculated.

[0058] Thus, assuming |X| > 1, the complex voltage U c to Uc=W(1,1)⋅λ(1,1)−i⋅W(2,1)⋅λ(2,2) and the complex current I c to Ic=W(2,1)⋅λ(1,1)−i⋅W(2,2)⋅λ(2,2) and for |X| ≤ 1 Ic=W(1,1)⋅λ(1,1)−i⋅W(2,1)⋅λ(2,2) Uc=W(2,1)⋅λ(1,1)−i⋅W(2,2)⋅λ(2,2) calculated. From these transformed stress parameters P u and current parameters P i can the complex AC resistance Z be calculated using Z=UcIc They can be calculated. The active resistance R and the imaginary AC resistance X are derived from the complex AC resistance Z. L and from that the inductance L=XL2πf calculated, whereby the linear position P is calculated using a lookup table 52.

[0059] Fig. Figure 8 shows an inaccuracy in the comparison of the different methods of position detection. Fig. 8 a) is the inaccuracy E R of the calculated resistance R and in Fig. 8 b) the inaccuracy E X of the calculated imaginary AC resistance X L each via the ratio of the imaginary AC resistance X L and the resistance R in comparison to calculation 58 from Fig. 5, the calculation 60 from Fig. 6 and the calculation 62 from Fig. Figure 7 shows that the imaginary AC resistance can be calculated most accurately using calculation 62. The calculation of the active resistance R can also be sufficiently accurate using this method. Reference symbol list 10 Fluid valve 12 Actuating part 14 Hydraulic part 16 first fluid channel 18 second fluid channel 20 third fluid channel 22 fourth fluid channel 24 first valve state 26 second valve state 28 third valve state 30 valve pistons 31 Control edge 32 Fluid channel 33 Electromagnet 34 coil 36 magnetic cores 42 spring force 44 Spring element 46 first direction of movement 48 second direction of movement 50 methods for position detection 52 Lookup Table 54 methods for valve control 55 Fluid pressure 56 Fluid volume flow 58 Calculation 60 Calculation 62 Calculation I a AC component I d Constant current component I c complex current I m measured coil current I n standardized current I n,m standardized current f frequency P Linear position P1 first linear position P2 second linear position Pn Intermediate linear position P i Current parameters P u Voltage parameters R real AC resistance U a AC component U d Constant voltage component U c complex tension U m measured actuation voltage U n normalized voltage U n,m normalized voltage X L imaginary AC resistance Z AC resistance

Claims

[1] Method for detecting the position (50) of a linear position (P) of an electromagnet (33) associated with a fluid valve (10), the electromagnet having at least one electrically operable coil (34) with an actuating voltage and a magnetic core (36) mounted so as to be translationally movable relative to the coil (34), which is movable by changing the linear position (P) depending on a coil current of the coil (34) built up by the actuating voltage, wherein the linear position (P) is detected by measuring the actuating voltage and the coil current and depending on the measured actuating voltage (U) m ) and the measured coil current (I m ) the linear position (P) is calculated, wherein the magnetic core (36) is movable against the spring force (42) of a spring element (44) while changing the linear position (P) and the linear position (P) of the magnetic core (36) acted upon by the spring force (42) is detected by the actuation voltage is applied as an alternating voltage to the coil (34), which causes an alternating current as coil current in the coil (34), the actuation voltage and the coil current are measured, from the measured actuation voltage (U m ) and the measured coil current (I m ) at least one voltage parameter (P u ) and a current parameter (P i ) are recorded and from the voltage parameter (P u ) and the current parameter (P i ) a complex AC resistance (Z) of the coil (34) is calculated and the linear position (P) is calculated as a function of the AC resistance (Z), characterized by , that the voltage parameters (P u ) and current parameters (P i ) by a singular value decomposition or principal component analysis of a correlation matrix (A) consisting of a normalized voltage (U) n,m ) the measured actuation voltage (U m) and a normalized current (I n,m ) of the measured coil current (I m ) has calculated components, will be calculated. [2] Method for position detection (50) according to claim 1, characterized by , that as a voltage parameter (P u ) a constant voltage component (U d ) and / or an alternating voltage component (U a ) the operating voltage is detected. [3] Method for position detection (50) according to claim 1 or 2, characterized by , that as current parameter (P i ) a constant current component (I d ) and / or an alternating current component (I a ) of the coil current can be detected. [4] Method for position detection (50) according to any one of the preceding claims, characterized by, that the magnetic core (36) assumes a first linear position (P1) when the coil current is absent and a second linear position (P2) when the coil current is applied against the spring force (42), and that the linear position to be detected is an intermediate linear position (Pn) lying between the first and second linear positions (P1, P2), in which the magnetic core (36) is acted upon by the spring force (42). [5] Method for position detection (50) according to any one of the preceding claims, characterized by , that the complex AC resistance (Z) is given by Z = X R + iX L composed of and from this a resistance (R) as the real AC resistance X R and an inductance L from the imaginary AC resistance X L with L=XL2πf The linear position (P) is calculated depending on the resistance R and the inductance L. [6] Method for position detection (50) according to claim 5, characterized by , that the linear position (P) is calculated depending on the resistance (R) and the inductance L via a lookup table (52). [7] Method for position detection (50) according to any one of the preceding claims, characterized by , that the measured actuation voltage (U m ) as complex voltage U c and the measured coil current (I m ) as complex current I c transformed and the complex AC resistance (Z) with Z = I c is calculated. [8] Method for controlling the valve (54) of a fluid valve (10) which can be actuated by an electromagnet (33) against the spring force (42) of a spring element (44) and which moves the magnetic core (36) to adjust a fluid pressure (55) and / or fluid volume flow rate (56) depending on a linear position (P) of the electromagnet (33) detected by a method for position detection (50) according to one of the preceding claims. [9] Fluid valve (10) comprising a valve piston (30) for adjusting a fluid pressure (55) and / or fluid volume flow rate (56), an electromagnet (33) with a translationally movable magnetic core (36) which is slidably coupled to the valve piston (30), characterized by , that the fluid valve (10) is controllable by the valve control method (54) according to claim 8.

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