DE102017208661A1 - DEVICE AND METHOD FOR DETERMINING A SPACING - Google Patents

Abstract

An apparatus for determining a distance comprises a transmitting device for transmitting a transmission signal having a first polarization direction and a signal reflector, which is designed to receive the transmission signal, based on the received transmission signal, a response signal having a second polarization direction, which is different from the first polarization direction is to send. The device comprises a receiving device, which is designed to determine the distance between the signal reflector and the transmitting device or the receiving device based on a phase position of the response signal with respect to the transmission signal.

Description

The present invention relates to an apparatus and a method for determining a distance. The present invention further relates to an apparatus and method for path measurement in hydraulic cylinders.

In DE 10 2004 062 801 A1 and DE 10 2009 055 445 A1 For example, concepts based on the measurement principle of position determination by phase evaluation of a returning wave are described. In DE 10 2009 055 363 A1 an evaluation of the phase position of two modes is described in order to increase the position accuracy.

For an evaluation of a phase position and / or a transit time information in order to be able to deduce a distance of an object, a distinction between the signal transmitted in the direction of the spaced object and the signal returned by the spaced object can be evaluated. This can lead to a superposition of the signals being obtained, in particular in the case of a local neighborhood or superimposition of a location of a transmitter and a receiver, which can increase the measurement effort and / or make the measurement results imprecise.

An object of the present invention is to provide a concept for determining a distance that allows a simple and accurate determination of a distance between a signal transmitter / receiver and a position sensor / signal reflector.

This object is solved by the subject matter of the independent patent claims.

A core idea of the present invention is to have recognized that by designing a trailing signal and a return signal such that they have orthogonal polarization directions of the respective signals, a spatial separation of the two signals can be obtained and utilized, resulting in a low mutual Influencing the signals allows, and / or requires little effort to separate the two signals, so that precise can be done with low interference and / or by simple means a distance determination.

According to one embodiment, a device for determining a distance comprises a transmitting device for transmitting a transmission signal having a first polarization direction. The apparatus includes a signal reflector configured to receive the transmit signal to generate and transmit a response signal having a second polarization direction different from the first polarization direction based on the received transmit signal. The apparatus further comprises a receiving device, which is designed to determine the distance between the signal reflector and the transmitting device or the receiving device based on a phase position of the response signal with respect to the transmission signal. The mutually different polarization directions allow a spatial separation of the transmission signal from the response signal and thus a simple and precise distance determination.

According to one embodiment, the transmission signal and / or the reception signal is a rotationally polarized signal, such as circularly polarized or elliptically polarized. A rotationally polarized signal enables the excitation of at least two modes in a propagation space of the corresponding transmission signal wave or response signal wave, wherein the modes can be arranged orthogonal to one another, which enables a high degree of evaluable information.

According to an embodiment, a rotational direction of a wave of the transmission signal and a rotational direction of a wave of the response signal are at least partially inverse to each other, wherein a first wave of the transmission signal and a second wave of the response signal have the orthogonal polarization directions based on the inverse rotational directions. This allows a simple embodiment of the transmitting device, the signal reflector and / or the receiving device, since rotationally polarized signals are easy to generate and can be done by reversing the direction of rotation of the polarization by a reflection of the wave.

According to one embodiment, the first polarization direction and the second polarization direction are orthogonal to one another. This enables a high quality of separation of the transmission signal from the response signal and high accuracy of the measurement result.

According to one embodiment, the device has a separator which is designed to separate the transmission signal from the reception signal. This allows a locally adjacent or integrated arrangement of the transmitting device and the receiving device.

In one embodiment, the device includes a polarizer configured to generate the transmit signal based on an obtained electrical signal. The use of a polarizer allows the use of mechanically and / or thermally robust components, which allows a high durability of the device.

In one embodiment, the polarizer is a septum polarizer configured to receive the electrical signal at a first interface and to provide the transmit signal. The septum polarizer is further configured to receive the response signal with a second interface and to provide an electrical receive signal based on the response signal. This allows the implementation of the transmitting device and the receiving device in one place, which is particularly advantageous for the determination of the distance in axially extending cavities, such as cylinders.

According to one embodiment, the device is formed as a fluid-filled cylinder for power transmission. The polarizer is disposed in a plug of the fluid-filled cylinder for power transmission. This allows a space-saving integration of the device in systems or devices in which a distance is to be determined.

According to one embodiment, the signal reflector comprises a polarization-transforming element which is designed to at least partially convert the first polarization into the second polarization. This allows a passive embodiment of the signal reflector, so that can be dispensed with a power supply of the signal reflector.

In one embodiment, the signal reflector is configured to provide the response signal having the first and second polarization directions. The receiving device has a first and a second interface and is configured to provide a first electrical reception signal based on the first polarization direction received at the first interface and a second electrical signal based on the second polarization direction received at the second interface. This makes it possible to evaluate two signals obtained based on the first polarization direction and the second polarization direction, which can be used, for example, to determine a rotational position of the signal reflector in a plane that is perpendicular to a direction along which the distance is determined is.

According to one embodiment, the device has an evaluation device, which is designed to determine, based on a correlation of the first electrical received signal and the second electrical received signal, a rotation of the signal reflector with respect to the transmitting device or the receiving device. This allows an information gain beyond the determination of the distance.

In one embodiment, the first interface is further configured to receive the electrical signal and to receive the first or second received electrical signal. This allows for a small number of components since the first interface is used both for transmitting and for receiving a wave.

According to one embodiment, the body of the signal reflector has a rotational asymmetry, such as a rotationally asymmetric recess or notch, wherein distortion is obtained in the response signal based on rotational asymmetry upon rotation of the signal reflector. This allows, based on different rotational orientations of the signal reflector different distortions in the response signal, which can be assigned to the rotational position.

According to one embodiment, the transmitting device is designed to emit the transmission signal with a first and a second polarization direction. The signal reflector is configured to generate the response signal with the second and a third polarization direction. This allows the use of other modes that can be arranged orthogonal to each other and thus a further increase in an information content of the measurement.

According to one embodiment, the signal reflector is arranged in a cavity in which the signal reflector with respect to the distance between the signal reflector and the transmitting device or the Receiving device is arranged variable, wherein the transmitting device is adapted to transmit the transmission signal with a TE-mode or a TM-mode and / or wherein the signal reflector is adapted to generate the response signal with a TE-mode or a TM-mode. The use of TE modes and / or TM modes allows precise generation of propagation of the corresponding signals.

According to one embodiment, the transmitting device is designed to generate the transmission signal with a TE-11 mode in the cavity. The signal reflector is configured to generate the response signal at the frequency of the transmit signal in the cavity. This allows easy generation of the transmission signal and the response signal.

According to one embodiment, the device is formed as a fluid-filled cylinder for power transmission, wherein the signal reflector is arranged on a piston of the fluid-filled cylinder for power transmission. This allows the position of the piston in the cylinder.

According to an exemplary embodiment, the receiving device is designed to emit a first transmission signal having a first frequency and a second transmission signal having a second frequency, wherein the signal reflector is designed to generate a first response signal with the first frequency and based on the second transmission signal based on the first transmission signal Transmit signal to generate a second response signal at the second frequency, wherein the receiving means is adapted to evaluate the phase position for the first and the second frequency to obtain a combined phase position information, and based on the combined phase position information to the position determine. For example, the device is designed to carry out a two-frequency measurement. This allows an enlargement of the measuring range in which the phase determination is unique with respect to the position of the signal reflector.

According to an exemplary embodiment, a method for determining a distance comprises transmitting, with a transmission device, a transmission signal having a first polarization direction and receiving the transmission signal with a signal reflector, and transmitting a response signal to the signal reflector having a second polarization direction, that of the first polarization direction is different based on the received transmission signal. The method further comprises receiving the response signal with a receiving device and determining the distance between the signal reflector and the transmitting device or the receiving device based on a phase position of the response signal with respect to the transmission signal.

Further advantageous embodiments are the subject of dependent claims.

• 1 ein schematisches Blockschaltbild einer Vorrichtung 10 gemäß einem Ausführungsbeispiel;
• 2a eine schematische perspektivische Darstellung eines Sendesignals gemäß einem Ausführungsbeispiel, das eine rotatorisch polarisierte Welle ist;
• 2b eine schematische perspektivische Ansicht eines Sendesignals gemäß einem Ausführungsbeispiel das als elliptisch polarisiertes Signal gebildet ist;
• 3 ein schematisches Blockschaltbild einer Vorrichtung gemäß einem Ausführungsbeispiel, bei dem der Signalreflektor in einem Hohlkörper angeordnet ist;
• 4 ein schematisches Blockschaltbild einer Vorrichtung gemäß einem Ausführungsbeispiel, bei dem die Vorrichtung einen Polarisator umfasst;
• 5 eine schematische perspektivische Ansicht einer Ausführung des Polarisators als Septum-Polarisator, gemäß einem Ausführungsbeispiel;
• 6 eine photographische Darstellung eines Polarisators gemäß einem Ausführungsbeispiel, der mit einem Hydraulikzylinder verbunden ist;
• 7 eine schematische perspektivische Ansicht eines Stopfens gemäß einem Ausführungsbeispiel;
• 8 ein schematisches Blockschaltbild einer Vorrichtung gemäß einem Ausführungsbeispiel, bei der der Polarisator als Septum-Polarisator gebildet ist und ausgebildet ist, um das Sendesignal basierend auf einem elektrischen Signal zu erzeugen;
• 9a eine schematische Aufsicht eines Signalreflektors gemäß einem Ausführungsbeispiel;
• 9b eine schematische Aufsicht auf einen weiteren Signalreflektor gemäß einem Ausführungsbeispiel, der die Aussparung aufweist;
• 10 ein schematisches Blockschaltbild einer Vorrichtung gemäß einem Ausführungsbeispiel, bei der die Sendeeinrichtung ein Separationsfilter aufweist;
• 11 ein schematisches Flussdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel;
• 12a-b schematische Seitenschnittansichten von Modenausbreitungen in einem als Koaxialanordnung ausgeführten Hohlkörper gemäß Ausführungsbeispielen;
• 12c-d schematische Seitenschnittansichten von Modenausbreitungen in einem als Hohlleiteranordnung ausführten Hohlkörper gemäß Ausführungsbeispielen; und
• 13 eine schematische Seitenschnittansicht einer Vorrichtung 130 gemäß einem Ausführungsbeispiel, die einen als fluidgefüllter Zylinder gebildeten Hohlkörper umfasst, in welchem ein Kolben beweglich angeordnet ist.

Preferred embodiments of the present invention will be explained below with reference to the accompanying drawings. Show it:

• 1 a schematic block diagram of a device 10 according to an embodiment;
• 2a a schematic perspective view of a transmission signal according to an embodiment, which is a rotatory polarized wave;
• 2 B a schematic perspective view of a transmission signal according to an embodiment which is formed as an elliptically polarized signal;
• 3 a schematic block diagram of a device according to an embodiment in which the signal reflector is arranged in a hollow body;
• 4 a schematic block diagram of a device according to an embodiment, in which the device comprises a polarizer;
• 5 a schematic perspective view of an embodiment of the polarizer as a septum polarizer, according to an embodiment;
• 6 a photographic representation of a polarizer according to an embodiment which is connected to a hydraulic cylinder;
• 7 a schematic perspective view of a plug according to an embodiment;
• 8th a schematic block diagram of a device according to an embodiment, wherein the polarizer is formed as a septum polarizer and is adapted to generate the transmission signal based on an electrical signal;
• 9a a schematic plan view of a signal reflector according to an embodiment;
• 9b a schematic plan view of another signal reflector according to an embodiment having the recess;
• 10 a schematic block diagram of a device according to an embodiment in which the transmitting device comprises a separation filter;
• 11 a schematic flowchart of a method according to an embodiment;
• 12a-b schematic side sectional views of Modenausbreitungen in a running as a coaxial hollow body according to embodiments;
• 12c-d schematic side sectional views of Modenausbreitungen in a executed as a waveguide assembly hollow body according to embodiments; and
• 13 a schematic side sectional view of a device 130 according to an embodiment which comprises a hollow body formed as a fluid-filled cylinder, in which a piston is movably arranged.

Before embodiments of the present invention are explained in detail with reference to the drawings, it is pointed out that identical, functionally identical or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description shown in different embodiments these elements is interchangeable or can be applied to each other.

1 shows a schematic block diagram of a device 10 for determining a distance 12 between a signal reflector 14 and a receiving device 16 or between the signal reflector 14 and a transmitting device 18 , The transmitting device 18 is designed to be a transmission signal 22 emanating, which is polarized at least with a first polarization direction P ₁ . If, for example, a three-dimensional Cartesian coordinate system with directions x, y and z is considered, then the first polarization direction can be arranged, for example, in a plane of the coordinate system, for example in an x / y plane. The signal reflector 14 is designed to receive the transmission signal 22 receive and based on the received transmit signal 22 a response signal 24 to send. The response signal 24 is polarized at least with a second polarization direction P ₂ . In the Cartesian coordinate system, the second polarization direction P _{2 may have} at least components that are orthogonal to the polarization direction P ₁ . An almost complete or complete orthogonality can be obtained, for example, if the polarization direction P _{2 is arranged} in a plane perpendicular to a plane in which the polarization direction P ₁ is arranged, for example the x / z plane.

For generating the second polarization direction, the signal reflector may comprise a polarization-changing element which is designed to at least partially convert the first polarization into the second polarization. For example, the signal reflector 14 Polarization filter and / or deflecting elements, which are formed to the transmission signal 22 repolarize so that the response signal 24 has the same or similar frequency or wavelength as the transmission signal 22 and neglecting any transformation losses except for the polarization direction of the transmission signal 22 equivalent. Alternatively, the repolarization may also be on a surface of the signal reflector 14 For example, an electrically conductive surface, such as a metal material or an electrically conductive polymer material, for example, electrically conductive polyurethane foams or the like may be obtained. According to one embodiment, the signal reflector is an element formed of the electrically conductive material, such as a metal element.

The receiving device 16 is designed to receive the response signal 24 to receive and based on a phase angle Δφ of the response signal 24 with respect to the transmission signal 22 the distance 12 between the signal reflector 14 and the transmitting device 18 and / or the receiving device 16 to determine. The receiving device 16 is designed to be an output signal based on the phase offset Δφ 33 to provide information regarding the distance 12 has or indicates this.

For example, the receiving device 16 a signal 26 from a signal source 28 the transmitting device 18 receive, which information with respect to a phase angle and / or a frequency of the transmission signal 22 indicates or the transmission signal 22 is. The transmission of the signal 26 can be wire-based and / or wireless. Alternatively, the transmitting device 16 also the transmission signal 22 synchronously with the transmitting device 18 produce. To send the transmission signal 22 can the transmitting device 18 one or more antenna structures 32a exhibit. To receive the response signal 24 can the receiving device 16 one or more antenna structures 32b exhibit. In later explained advantageous Embodiments may be the antenna structures 32a and 32b also be identical, that means, be usable both as transmitting and as receiving antennas.

Although the receiving device 16 locally adjacent to the transmitter 18 is shown, the receiving device 16 also spaced from the transmitting device 18 be positioned. The phase angle Δφ can also in such a configuration with a total distance, the transmission signal 22 and the response signal 24 reflect, so that upon a knowledge of a relative position or a distance between the receiving device 16 and the transmitting device 18 to a distance between the signal reflector 14 and the receiving device 16 and / or the transmitting device 18 can be concluded.

An advantage of the mutually different polarization directions is that they have at least portions that are orthogonal to each other in the illustrated Cartesian coordinate systems. This means that the polarization directions P ₁ and P _{2 can} also be linearly dependent on each other, wherein the polarization direction P ₁ and P ₂ can be split at least into components which are arranged orthogonal to one another. The receiving device 16 can be designed to perform the evaluation of the phase angle Δφ with respect to the orthogonal components. The advantage of this is that the polarization direction P ₁ and P ₂ or their orthogonal components are spatially independent of one another. This means that the transmission signal 22 and the response signal 24 spatially superimposed and can be evaluated simultaneously based on the mutually different polarization directions in the same place.

2a shows a schematic perspective view of a transmission signal 22 ' according to an embodiment. The transmission signal 22 ' may be a rotationally polarized wave, such as a circularly polarized wave and / or an elliptically polarized wave. The circularly polarized wave of the transmission signal 22 ' For example, it can propagate left or right handed along the x direction. With the x / y and x / z planes at least partially spanned by the x-direction, signal components or wave components can be used 34a and 34b can be projected, which may have a phase offset to each other and are arranged orthogonal to each other. That is, by using a circularly polarized wave, an at least two-polarized wave can be obtained which enables mode excitation in both spatial directions y and z. A rotating circularly polarized or elliptically polarized wave may be obtained by a septum polarizer, but is not limited thereto. Other polarizers can also produce a rotating shaft.

2 B shows a schematic perspective view of a transmission signal 22 " , which may be formed, for example, as an elliptically polarized signal. This makes it possible to obtain different amplitudes of the signal components 34a and 34b in the levels x / y and x / z.

The in the 2a and 2 B shown transmission signals 22 ' and 22 " may be referred to as rotationally polarized signals, which may be elliptical ( 2 B ) and / or as a special form thereof as well as circular ( 2a ) is implementable.

The in the 2a and 2 B exemplified in several spatial directions polarized waves 22 ' and 22 " allow a mode excitation in at least two spatial directions, which is useful for a high degree of information. By an impact of the transmission signals 22 ' and or 22 " On the signal reflector, for example comprising a metal material or a ceramic material, a direction of rotation, ie direction of polarization P _1, in the reflected-back reflected response signal can be reversed. This means that one direction of rotation of a wave of the transmission signal 22 ' or 22 " and a direction of rotation of a wave of the response signal may be at least partially inverse to each other. The directions of rotation may correlate with or represent the polarization directions, such that a wave of the transmission signal 22 ' or 22 " the polarization direction P _{1 has,} for example, a left-hand rotation and a wave of the response signal is, for example, clockwise based on the inverse rotational directions and thus has the second polarization direction, wherein the inverse rotational directions can provide an orthogonality of the polarization directions.

The transmitting device 18 the device 10 may be configured to emit correspondingly rotatory polarized waves, that is, the transmission signal 22 can by the transmission signal 22 ' and or 22 " to be provided.

Both the representation of the polarization directions in the 1 as well as the possible direction reversal of the rotationally polarized signals 22 ' and 22 " for the response signals, the first polarization direction P ₁ and the second polarization direction P _{2 may be} orthogonal to each other. The Orthogonality allows spatial separation of the signals, despite a local superimposition of the transmission signal and the response signal.

3 shows a schematic block diagram of a device 30 according to an embodiment, wherein the signal reflector 14 in a hollow body 36 is arranged, for example, a cylinder. The signal reflector 14 can be inside the hollow body 36 be arranged so that the distance 12 between the signal reflector 14 and a reference position 38 , For example, an edge or end of the hollow body 36 is changeable. The transmitting device 18 and / or the receiving device 16 can with the reference position 38 be connected so that the transmission signal 22 at the reference position 38 in the hollow body 36 can be routed and / or the response signal 24 at the reference position 38 can be received. The device 30 can a separator 42 formed to be the transmission signal 22 from the received signal 24 to separate. For example, the separator may be separate transmitting and receiving structures, which are part of the transmitting device 18 and / or receiving device 16 are or are associated with them. The separator 42 is formed to the spatially separated signals 22 and 24 to send and / or receive.

According to one embodiment, the device 30 a polarizer 44 which is configured to be based on an obtained electrical signal 46 the transmission signal 22 to create. At the electrical signal 46 For example, it may be one from the signal source 28 act signal that has been optionally further amplified, as shown in the 1 is shown. The polarizer 44 may be configured to be based on the electrical signal 46 generate an electrical and / or magnetic signal that at least part of the transmission signal 22 provides. The polarizer 44 may be configured to receive the transmission signal 22 to produce linearly polarized or rotationally polarized. This means that, as has already been described above, the transmission signal 22 also by the transmission signal 22 ' and or 22 " can be provided.

The signal reflector 14 is designed to receive the transmission signal 22 to receive and the response signal 24 based on this. This can be done, for example, by a reflection of the transmission signal 22 on a surface or body of the signal reflector 14 done so that the process of creating the response signal 24 can be passive. Both the transmission signal 22 as well as the response signal 24 may be formed to at least one mode in the hollow body 36 to stimulate.

At the reference position 38 can be a superposition of the modes of the transmission signal 22 and the response signal 24 be obtained, the separator 42 may be formed to the response signal 24 with a receiving structure, such as the receiving structure 32b to receive and receive an electrical signal 48 to provide the phase evaluation, allowing the signal 33 is available.

4 shows a schematic block diagram of a device 40 according to an embodiment, wherein the polarizer 44 additionally the function of the separator 42 provides. The polarizer 44 For example, it may be embodied as a septum polarizer configured to receive the electrical signal 46 at a first interface 52a and, based on this, the transmission signal 22 to produce or provide. The septum polarizer 44 is further configured to receive the response signal 24 with a second interface 52b to receive and receive the electrical signal 48 based on the response signal 24 provide. The interfaces 52a and or 52b can be related to the 1 explained transmitting and receiving devices 32a and or 32b at least partially, so that the polarizer 44 also the transmitting device 18 and / or the receiving device 16 at least partially.

5 shows a schematic perspective view of an embodiment of the polarizer 44 as a septum polarizer. The septum polarizer 44 can be a partition structure 56 have, for example, is formed stepwise and the interfaces 52a and 52b (not shown) or the transmission structure 32a and the reception structure 32b from each other in one of the polarizer 44 irradiated cavity spaced. The partition wall structure 56 can be formed comprising an electrically conductive material. The polarizer 44 can as a closure of the hollow body 36 be formed. For example, the hollow body 36 a fluid-filled cylinder for power transmission, such as a pneumatic cylinder or a hydraulic cylinder, which is adapted to be filled with a fluid, that is, a gas or a liquid such as a hydraulic oil and / or to move a plunger. The signal reflector 14 For example, it can be arranged on the ram to be moved, so that based on the determined distance 12 also the position of the plunger in the cylinder can be determined. The polarizer 44 can be in a cap or plug of the hydraulic cylinder 36 be integrated so that an exact position detection can be obtained with little additional or external effort.

6 shows a photographic representation of a polarizer, such as the polarizer 44 that with the hollow body 36 , which is formed as a hydraulic cylinder is connected. The polarizer 44 can be a circuit board 62 which is configured to receive the signal 46 to receive and the signal 48 provide. About coaxial cable connections 64 can the circuit board 62 with the interfaces 52a and 52b be connected. As has already been described, the hollow body according to embodiments may be formed as a gas or liquid-filled cylinder for power transmission, ie, as a pneumatic cylinder or as a hydraulic cylinder. Embodiments described herein relate to the path measurement in such a cylinder and therefore may be independent of an actually filled fluid fill. This means that embodiments also relate to partially or unfilled hollow bodies or fluid-fillable, ie, with a fluid (gas or liquid such as a hydraulic oil) fillable hollow body. However, the embodiments described herein are not limited thereto.

7 shows a schematic perspective view of a plug 70 that the hollow body 36 closes and the transmission structures 32a and the reception structures 32b includes as well as the interfaces 52a and 52b provides. Apart from cable connections and / or a power supply, it may be possible, without further great effort, to determine the position in the hollow body 36 perform.

8th shows a schematic block diagram of a device 80 in which the polarizer is formed as a septum polarizer and is designed to receive the transmission signal 22 ' based on the electrical signal 46 (U _down ) to produce. The transmission signal 22 ' is designed so that it can in the directions y and z each TE mode, for example, the TE11 mode can stimulate. That is, along the propagation direction x, the transmission signal 22 ' be sent out with a TE-mode, the signal reflector 14 can also generate the response signal in the TE mode. Alternatively, another frequency and / or another mode, for example a higher TE mode or a TEM or a TEM mode can be excited. The use of a mode allows at least substantially stationary positioning of minima and maxima, so that, for example, a maximum of the field can be arranged at the location of the transmitting and receiving structures.

Although the signal reflector 14 can be designed to receive the response signal 24 to actively generate what makes it possible to obtain the transmission signal with a first mode, such as a TE mode, and to excite the response signal with another mode, such as a TEM mode, is the signal reflector 14 preferably passively formed, so that the transmitting device is designed to receive the transmission signal 22 . 22 ' or 22 " with a mode, such as a TE11 mode in the cavity 36 to generate, with the signal reflector 14 is formed to the response signal 24 with the frequency of the transmission signal 22 . 22 ' respectively. 22 " in the cavity, that is, a frequency can remain unchanged so that an identical mode is also excited.

In other words, embodiments make it possible to obtain a device for determining the position of the piston in a hydraulic cylinder. The position can be determined by determining the phase angle of the excited in the hydraulic cylinder electromagnetic wave. The leading and the returning wave (send signal 22 and response signal 24 ) can be spatially separated, which allows the use of cost-effective evaluation. For this purpose, two or more orthogonal modes of the hydraulic cylinder assembly are used to spatially separate, describe or include the reciprocating wave. Such waves or modes can be obtained by the use of polarizers in the hydraulic cylinder. One aspect of the embodiments described herein includes the spatial separation of the reciprocating shaft in one of the assemblies of the hydraulic cylinder. For example, in the arrangement, two (or more) spatially orthogonal modes, such as two orthogonal TE11 modes, are excited such that the outgoing wave is elliptically or circularly polarized. The direction and the degree of polarization of the field rotation are achieved, for example, by means of a suitable phase shift between the two modes. This task can be a polarizer, such as the polarizer 44 assume that both outside, see 6 , the hydraulic cylinder as well as in a transition of the hydraulic cylinder, see 7 , can be integrated. The direction of rotation of the waves excited by the polarizer may be inverse or inverse to the return wave of the device reflected by the piston (signal reflector). Therefore, the returning wave at the complementary input of the polarizer can be detected and thus spatially decoupled from the outgoing wave, as in 8th which illustrates the principle of separating counter-rotating back and forth waves in the array by means of a polarizer.

The arrangement useful for verifying such an approach may include an external or internal polarizer and a transition of the waveguide assembly of the hydraulic cylinder, which is schematically illustrated in FIG 6 is shown. The polarizer can have one input and one output, each with two Connections, such as SNA connections, be connected. Taken together, two terminals can pass a potential as well as a reference potential and be jointly designed to generate a wave or to convert a received wave into an electrical signal. The polarizer may have four inputs, so that one differential input can be provided each comprising two terminals for each of the two TE11 modes. Through the input of the polarizer a left-handed or alternatively clockwise rotating circular-polarized wave (trailing wave in the waveguide) can be created. The return from the piston shaft is reversely rotating, ie clockwise or counterclockwise circularly polarized and can be passed to the output of the polarizer.

Furthermore, it is possible to integrate the polarizer, possibly also a part of the evaluation of the measuring system, in the ceramic plug, for example in the form of a so-called "septum polarizer".

9a shows a schematic plan view of a signal reflector 14 ' for example as a signal reflector 14 can be used. The embodiments described above have been described, inter alia, such that a polarization reversal or a polarization change by the signal reflector 14 is obtained, for example by reversing a direction of rotation of a rotationally polarized wave. Such reshaping can occur almost completely, which allows almost complete spatial separation of the traveling and returning waves, the transmission signal and the response signal.

This is obtained inter alia by a symmetry of the signal reflector with respect to the space in which it is arranged. For example, in a cylindrical cavity, a round signal reflector which is rotationally symmetric with respect to a cross-section of the cylinder may allow for complete or nearly complete repolarization. A rotational asymmetry allows incomplete repolarization, that is, a body of the signal reflector 14 ' may have a rotational asymmetry, wherein based on the rotational asymmetry in a rotation of the signal reflector, a distortion in the response signal is obtained. The rotational asymmetry may result in incomplete repolarization, with a degree of incomplete repolarization and / or attenuation in a maximum or minimum of the response signal 24 with respect to the transmission signal 22 from a rotation angle α of the signal reflector 14 ' with respect to the transmitting device 18 or the receiving device 16 influenced or dependent. Such a rotation asymmetry can, for example, by a recess or a thickening 66 obtained, for example, a variable material thickness of a reflective material of the signal reflector 14 ' provides. For example, such a material in the region of the recess 66 thickened, diluted or absent. This means that rotational asymmetry can be at least partially implemented by a recess in the body. Alternatively, it is also possible that the rotational asymmetry is obtained by other embodiments, such as a rotationally asymmetric side section or cross section of the body.

9b shows a schematic plan view of another signal reflector 14 " , the recess 66 For example, in an edge region, wherein the recess 66 through one of the material of the signal reflector 14 " different material 68 at least partially filled, such as to maintain a tightness in the hydraulic cylinder. Alternatively, the signal reflector may also have another, non-circular shape, such as a polygonal shape or a free-form surface, which is possibly placed on a body to be tracked, regardless of sealing functions. This also allows rotation of the signal reflector.

In other words, a rotational asymmetry of the signal reflector allows the response signal 24 has both the first polarization direction and the second polarization direction. Alternatively, the transmitting device can also be designed to emit the transmission signal, for example with a first and a second polarization direction. The signal reflector may be configured to generate the response signal with the first or second polarization direction and additionally a third polarization direction. The third direction of polarization may possibly be orthogonal to the first and second directions of polarization, that is, the determination of the rotation of the signal reflector may be made without sacrificing measurement accuracy and / or spatial separation. The phase evaluation with respect to the first polarization direction and the second polarization direction still allows the distance determination.

A comparison of a portion of the first polarization direction and the second polarization direction in the response signal also allows a determination of the rotation of the signal reflector 14 " or 14 ' opposite the transmitting device 18 or the receiving device 16 ,

In embodiments, the signal reflector is designed to receive the response signal 24 to provide such that it has the first and the second polarization direction. The receiving device may have a first and a second interface and may be configured to provide a first electrical reception signal based on the first polarization direction received at the first interface and a second electrical reception signal based on the second polarization direction received at the second interface. These electrical signals can be used to evaluate the rotation angle. For example, in the 4 . 5 . 6 or 7 described polarizer to be formed on one of the transmission structures 32a also the response signal 24 at least partially received. For this, the reception structure 32a For example, be connected to a separator or filter that allows simultaneous use for transmitting the transmission signal as well as receiving the response signal with the same polarization direction. This means the transmission signal 22 and the response signal 24 can be at the location of the broadcasting structure 32a overlay and still be evaluated.

10 shows a schematic block diagram of a device 100 in which the transmitting device 18 a separation filter 68 which is adapted to the response signal 24 , also on the broadcasting structures 32a is received from the transmission signal 22 to separate, leaving another electrical signal 72 which receives information regarding the response signal 24 having the first polarization direction. The electrical signal 72 can the reception structure 16 be provided so that based on a comparison between the electrical signals 48 and 72 an information about the rotation angle α in the signal 33 is available. That means the receiving device 16 an evaluation device 74 which is configured to be based on a correlation of the received electrical signals 48 and 72 a rotation of the signal reflector 14 ' with respect to the transmitting device 18 or the receiving device 16 or both facilities 16 and 18 to determine.

For example, the interface 52a be formed to both the electrical signal 46 to receive as well as to the electrical signal 72 , depending on the direction of polarization, the electrical signal 48 provide.

Although embodiments described above rely on the generation of the transmission signal 22 . 22 ' or 22 " and the response signal 24 With reference to the fact that the corresponding signals are excited or generated at a frequency, it is also possible to design embodiments described herein in such a way that the transmitting device is designed to transmit a first transmission signal with a first frequency and a second transmission signal with a second frequency, wherein the signal reflector is configured to generate a first response signal having a first frequency based on the first transmission signal and a second response signal having a second frequency based on the second transmission signal. The receiving device may be configured to evaluate the phase position for the first and the second frequency in order to obtain a combined phase position formation, and to determine the position based on the combined phase position information. This can also be understood that the device can be designed to carry out the phase determination at two mutually different frequencies, that is, to perform a so-called "two-frequency" or "multi-frequency" measurement, if the measurement for a higher number of Frequencies is repeated. This allows to enlarge the area within which the distance 12 is clearly determinable, since ambiguities can be reduced or prevented at a single frequency after a phase rotation of 180 ° or 360 °.

11 shows a schematic flow diagram of a method 1100 according to an embodiment. A step 1110 comprises a transmission of a transmission signal comprising a first polarization direction with a transmission device. A step 1120 comprising receiving the transmit signal and transmitting a response signal with a signal reflector, wherein the response signal has a second polarization direction that is different from the first polarization direction. The response signal is provided and transmitted based on the received transmission signal. In one step 1130 the response signal is received by a receiving device and a distance between the signal reflector and the transmitting device or the receiving device is determined based on the phase position of the response signal with respect to the transmitted signal.

The embodiments described herein have the advantage that a construction of a cheap and sensitive reader is made possible because it allows a spatial separation of the reciprocating wave based on different polarizations, such as by exciting two orthogonal modes by means of rotationally polarized waves. The embodiments described herein can be used for path measurement, in particular in cavities and in particular in hydraulic cylinders for position measurement.

12a shows a schematic side sectional view of the executed as a coaxial hollow body 36 in which the TEM mode is excited, where solid lines represent electric field lines and dashed lines represent magnetic field lines. Based on a rotationally polarized wave, a direction of the field lines may change along an axial direction perpendicular to the illustrated plane.

12b shows a schematic side sectional view of the executed as a coaxial hollow body 36 out 12a in which the TE11 mode is excited.

abhängig sein, wobei f die Frequenz und c₀ die Lichtgeschwindigkeit beschreiben. Des Weiteren kann jeder Mode die Grenzwellenzahl k_c aufweisen, womit die Ausbreitungskonstante β $$\beta =\sqrt{{\kappa }^2-{\kappa }_c{}^2}$$

bestimmbar ist, die eine geführte Wellenlänge λ_g mit $${\lambda }_g=\frac{2\pi }{\beta }$$

beschreibt. Ferner können Dämpfungsverluste, etwa Verluste in Hydraulikhöhe durch die Dämpfungskonstante α beschrieben werden, mit: $$\alpha =\frac{{\kappa }^2\text{tan}\delta }{2\beta }$$

Specific field distributions of the generate transmission signals and / or response signals, which may also be referred to as modes, may be dependent on a geometry of the respective hollow body, for example a cross section of a cylinder or the cross sections of the respective cylinders of a hydraulic cylinder. The field distribution of the respective mode can depend on the wave number $$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

be dependent, where f is the frequency and c _{0 describe} the speed of light. Furthermore, each mode can have the limiting wave number k _c , whereby the propagation constant β $$\beta =\sqrt{{\kappa }^2-{\mathrm{<figure-callout\; id="2"\; label="\kappa \; c"\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa \; </figure-callout>}}_c{}^2}$$

can be determined, which has a guided wavelength λ _g $${\lambda }_G=\frac{2\pi }{\beta }$$

describes. Furthermore, loss losses, such as losses in hydraulic height can be described by the damping constant α, with: $$\alpha =\frac{{\mathrm{<figure-callout\; id="2"\; label="\kappa "\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa </figure-callout>}}^2\text{<figure-callout id="2" label="tan δ" filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png" state="{{state}}">tan </figure-callout>}\delta }{2\beta }$$

The losses of the electromagnetic wave due to the relatively small surface resistance, for example when the hollow body 36 is formed as a steel shell, and a rod of the hydraulic cylinder can be neglected against the losses in the hydraulic oil. The propagation and damping constants of the modes go into the phase component -2Iβ with I corresponding to the distance 12 or in the amplitude ^component e ^{-2Ia of} the transfer function of the reflection line, which is formed by the cylinder. I thus designates the piston position. For performing measurement methods according to embodiments described herein, for example, the first two modes capable of propagation may be of interest to the respective arrangements in the hydraulic cylinder. These two modes are for example the TEM mode and the TE11 mode.

In 12c schematically is a propagation of a TE11 mode in a cylindrical hollow body 36 represented, which is implemented as a waveguide arrangement.

12d schematically shows a propagation of a TM01 mode in the cylindrical hollow body 36 out 12c ,

For example. For example, a reciprocating piston assembly may include a piston that is partially disposed in and guided in a cylindrical hollow body. In a region of the hollow body in which the piston is arranged, the coaxial view of the 12a and 12b be applied to determine which signal is to be transmitted from the transmitter. In a region in which the piston is absent and, for example, only oil is arranged in the cylinder, the waveguide arrangement can be used. This means that depending on a position of the transmitting device and / or the signal reflector of different modes can be excited.

The following table shows a comparison of the TEM mode and the TE11 mode, for example for the coaxial arrangement.

$$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

(10) Grenzwellenzahl $${\kappa }_c=\frac{\mathrm{1,841}}{\alpha }$$

$${\kappa }_c=\frac{\mathrm{2,405}}{\alpha }$$

(11) Ausbreitungskonstante $$\beta =\sqrt{{\kappa }^2-{\kappa }_c{}^2}$$

$$\beta =\sqrt{{\kappa }^2-{\kappa }_c{}^2}$$

(12) geführte Wellenlänge $${\lambda }_g=\frac{2\pi }{\beta }$$

$${\lambda }_g=\frac{2\pi }{\beta }$$

(13) Dämpfungskonstante $$\alpha =\frac{{\kappa }^2\text{tan}\delta }{2\beta }$$

$$\alpha =\frac{{\kappa }^2\text{tan}\delta }{2\beta }$$

(14) The line parameters of the TEM mode and the TE11 mode: TE11 mode TM01 mode wavenumber $$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

$$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

(10) Cross wave number $${\kappa }_c=\frac{1.841}{\alpha }$$

$${\kappa }_c=\frac{2.405}{\alpha }$$

(11) propagation constant $$\beta =\sqrt{{\kappa }^2-{\mathrm{<figure-callout\; id="2"\; label="\kappa \; c"\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa \; </figure-callout>}}_c{}^2}$$

$$\beta =\sqrt{{\kappa }^2-{\mathrm{<figure-callout\; id="2"\; label="\kappa \; c"\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa \; </figure-callout>}}_c{}^2}$$

(12) guided wavelength $${\lambda }_G=\frac{2\pi }{\beta }$$

$${\lambda }_G=\frac{2\pi }{\beta }$$

(13) damping constant $$\alpha =\frac{{\mathrm{<figure-callout\; id="2"\; label="\kappa "\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa </figure-callout>}}^2\text{<figure-callout id="2" label="tan δ" filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png" state="{{state}}">tan </figure-callout>}\delta }{2\beta }$$

$$\alpha =\frac{{\mathrm{<figure-callout\; id="2"\; label="\kappa "\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa </figure-callout>}}^2\text{<figure-callout id="2" label="tan δ" filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png" state="{{state}}">tan </figure-callout>}\delta }{2\beta }$$

(14)

$$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

(10) Grenzwellenzahl $${\kappa }_c=\frac{\mathrm{1,841}}{\alpha }$$

$${\kappa }_c=\frac{\mathrm{2,405}}{\alpha }$$

(11) Ausbreitungskonstante $$\beta =\sqrt{{\kappa }^2-{\kappa }_c{}^2}$$

$$\beta =\sqrt{{\kappa }^2-{\kappa }_c{}^2}$$

(12) geführte Wellenlänge $${\lambda }_g=\frac{2\pi }{\beta }$$

$${\lambda }_g=\frac{2\pi }{\beta }$$

(13) Dämpfungskonstante $$\alpha =\frac{{\kappa }^2\text{tan}\delta }{2\beta }$$

$$\alpha =\frac{{\kappa }^2\text{tan}\delta }{2\beta }$$

(14) The following table shows the corresponding parameters for the 12c and 12d represented TE11 or TEM01 modes. TE11 mode TM01 mode wavenumber $$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

$$\kappa =\frac{2\pi f\sqrt{{\epsilon }_r}}{c_0}$$

(10) Cross wave number $${\kappa }_c=\frac{1.841}{\alpha }$$

$${\kappa }_c=\frac{2.405}{\alpha }$$

(11) propagation constant $$\beta =\sqrt{{\kappa }^2-{\mathrm{<figure-callout\; id="2"\; label="\kappa \; c"\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa \; </figure-callout>}}_c{}^2}$$

$$\beta =\sqrt{{\kappa }^2-{\mathrm{<figure-callout\; id="2"\; label="\kappa \; c"\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa \; </figure-callout>}}_c{}^2}$$

(12) guided wavelength $${\lambda }_G=\frac{2\pi }{\beta }$$

$${\lambda }_G=\frac{2\pi }{\beta }$$

(13) damping constant $$\alpha =\frac{{\mathrm{<figure-callout\; id="2"\; label="\kappa "\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa </figure-callout>}}^2\text{<figure-callout id="2" label="tan δ" filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png" state="{{state}}">tan </figure-callout>}\delta }{2\beta }$$

$$\alpha =\frac{{\mathrm{<figure-callout\; id="2"\; label="\kappa "\; filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png"\; state="\{\{state\}\}">\kappa </figure-callout>}}^2\text{<figure-callout id="2" label="tan δ" filenames="DE102017208661A1\_0025.png,DE102017208661A1\_0026.png" state="{{state}}">tan </figure-callout>}\delta }{2\beta }$$

(14)

A frequency range within which the transmission signal and / or the response signal can be excited results, for example, from the guided wavelength via the relationship λ = c / f, with a tolerance range of ± 25%, ± 10% or ± 5% or less can describe sufficient drive frequency to propagate the mode.

13 shows a schematic side sectional view of a device 130 according to an embodiment, the hollow body formed as a fluid-filled cylinder for power transmission 36 includes, in which a piston 58 is movably arranged. An outside of the piston 58 can the signal reflector 14 be formed. For this purpose, the piston 58 For example, be formed from an electrically conductive material. Alternatively, a separate element may be disposed on the piston to form the signal reflector. The side or the separate element may have rotational asymmetry.

The device 130 includes the stopper 70 , About the example. Fluid in the hollow body 36 filled and / or can be drained from this. In a first area 36a of the hollow body 36 can in the absence of the piston 58 a wave propagation according to the 12c-d through the transmitting device or the plug 70 to be obtained. In a second area 36b of the hollow body 36 may be based on the presence of the electrically conductive piston 58 a wave propagation according to the 12a-b to be obtained. This means that a changed position of the transmitting device or of the plug and / or of the signal reflector can be implemented without restriction by another mode excitation.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

Depending on particular implementation requirements, embodiments of the invention may be implemented in hardware or in software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM or FLASH memory, a hard disk, or other magnetic disk or optical memory are stored on the electronically readable control signals that can cooperate with a programmable computer system or cooperate such that the respective method is performed. Therefore, the digital storage medium can be computer readable. Thus, some embodiments according to the invention include a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is performed.

In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is operable to perform one of the methods when the computer program product runs on a computer. The program code can also be stored, for example, on a machine-readable carrier.

Other embodiments include the computer program for performing any of the methods described herein, wherein the computer program is stored on a machine-readable medium.

In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for performing one of the methods described herein when the computer program runs on a computer. A further embodiment of the inventive method is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program is recorded for carrying out one of the methods described herein.

A further embodiment of the method according to the invention is thus a data stream or a sequence of signals, which represent the computer program for performing one of the methods described herein. The data stream or the sequence of signals may be configured, for example, to be transferred via a data communication connection, for example via the Internet.

Another embodiment includes a processing device, such as a computer or a programmable logic device, that is configured or adapted to perform one of the methods described herein.

Another embodiment includes a computer on which the computer program is installed to perform one of the methods described herein.

In some embodiments, a programmable logic device (eg, a field programmable gate array, an FPGA) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform one of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be a universal hardware such as a computer processor (CPU) or hardware specific to the process, such as an ASIC.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004062801 A1 [0002]
• DE 102009055445 A1 [0002]
• DE 102009055363 A1 [0002]

Claims (21)

Device for determining a distance (12) having the following features: a transmitting device (18) for transmitting a transmission signal (22; 22 ') having a first polarization direction (P ₁ ); a signal reflector (14; 14 '; 14 ") configured to receive the transmission signal (22; 22', 22") for generating a response signal (24. 24) based on the received transmission signal (22; 22 ', 22 ") ) having a second polarization direction (P ₂ ) different from the first polarization direction (P ₁ ); receiving means (16) arranged to detect, based on a phase angle (Δφ) of the response signal (24) Transmitting signal (22) to determine the distance (12) between the signal reflector (14, 14 ', 14 ") and the transmitting device (18) or the receiving device (16). Device according to Claim 1 in which the transmission signal (22 ', 22 ") and / or the reception signal (24) is a rotationally polarized signal. Device according to Claim 2 in which a direction of rotation of a wave of the transmission signal (22 ', 22 ") and a direction of rotation of a wave of the response signal (24) are at least partially inverse to one another, wherein a first wave of the transmission signal (22', 22") is the first polarization direction (P ₁ ) and a second wave of the response signal (24) based on the inverse rotational directions, the second polarization direction (P ₂ ) which is orthogonal to the first polarization direction. Device according to one of the preceding claims, in which the first polarization direction (P ₁ ) and the second polarization direction (P ₂ ) are orthogonal to one another. Apparatus according to any one of the preceding claims, including a separator (42) arranged to separate the transmit signal (22; 22 ', 22 ") from the response signal (24). Apparatus according to any one of the preceding claims, comprising a polarizer (44) adapted to generate the transmit signal (22; 22 ', 22 ") based on an obtained electrical signal (46). Device according to Claim 6 wherein the polarizer (44) is a septum polarizer configured to receive the electrical signal (46) at a first interface (52a) and to provide the transmit signal (22; 22 ', 22 ") the septum polarizer is further configured to receive the response signal (24) with a second interface (52b) and to provide an electrical receive signal (48) based on the response signal (24). Device according to Claim 6 or 7 in which the polarizer (44) at least partially provides the transmitting device (18) and the receiving device (16). Device according to one of the Claims 6 to 8th formed as a fluid-fillable cylinder for power transmission, wherein the polarizer (44) is disposed in a plug (70) of the fluid-fillable cylinder for power transmission. Device according to one of the preceding claims, wherein the signal reflector (14; 14 ', 14 ") comprises a polarization-transforming element which is designed to at least partially convert the first polarization direction (P ₁ ) into the second polarization direction (P ₂ ). Apparatus according to any one of the preceding claims, wherein the signal reflector (14 ', 14 ") is adapted to provide the response signal (24) having the first and second polarization directions (P ₁ , P ₂ ), the receiving means (16) has first and second interfaces (52a, 52b) and is configured to generate a first electrical reception signal (72) based on the first polarization direction (P ₁ ) received at the first interface (52a) and a second electrical reception signal ( 48) based on the second polarization direction (P ₂ ) received at the second interface (52b). Device according to Claim 11 comprising an evaluation device (74) which is designed to determine, based on a correlation of the first electrical reception signal (72) and the second electrical reception signal (48), a rotation (α) of the signal reflector (14 ', 14 ") with respect to the transmission device (18) or receiving device (16) to determine. Device according to Claim 11 or 12 in that the first interface (52a) is further adapted to receive the electrical signal (46) and to receive the first or second received electrical signal (46; 72). Device according to one of the Claims 11 to 13 in which a body of the signal reflector (14 ', 14 ") has rotational asymmetry, and based on rotational asymmetry, upon rotation (α) of the signal reflector (14', 14"), distortion is obtained in the response signal (24). Device according to Claim 14 in that the rotational asymmetry is at least partially implemented by a recess (66) in the body. Device according to one of the preceding claims, in which the transmitting device (18) is designed to emit the transmission signal (22; 22 '; 22 ") with the first of a second polarization direction (P ₁ ) and in which the signal reflector (14'; 14 ") is configured to generate the response signal with the second (P ₂ ) and a third polarization direction. An apparatus according to any one of the preceding claims, wherein the signal reflector (14; 14 '; 14 ") is disposed in a cavity (36) in which the signal reflector (14; 14'; 14") is spaced from (12) between the signal reflector Signal Reflector (14; 14 '; 14 ") and the transmitting device (18) or the receiving device (16) is arranged variable, wherein the transmitting device (18) is adapted to the transmission signal (22; 22'; 22") with a TE Mode or a TM mode and / or wherein the signal reflector (14; 14 '; 14 ") is designed to generate the response signal (24) with a TE mode or a TM mode. Device according to Claim 17 in which the transmitter means (18) is adapted to generate the transmit signal (22; 22 '; 22 ") with a TE11 mode in the cavity (36), and wherein the signal reflector (14; 14';14"). ) is configured to generate the response signal (24) at the frequency of the transmit signal (22; 22 '; 22 ") in the cavity. Apparatus as claimed in any one of the preceding claims, which is formed as a fluid-fillable power transfer cylinder (130), the signal reflector (14; 14 '; 14 ") being disposed on a piston (58) of the fluid-mountable cylinder for power transmission. Device according to one of the preceding claims, in which the transmitting device (18) is designed to produce a first transmission signal (22; 22 '; 22 ") at a first frequency and a second transmission signal (22; 22'; 22") at a second frequency The signal reflector (14; 14 ', 14 ") is designed to generate, based on the first transmit signal (22; 22'; 22"), a first response signal (24) having the first frequency and based on the second transmit signal (22; 22, 22 ', 22 ") to generate a second response signal (24) at the second frequency, wherein the receiving means (16) is adapted to evaluate the phase relationship (Δα) for the first and second frequencies to provide combined phase angle information and to determine the distance (12) based on the combined phasing information. Method (1100) for determining a distance comprising the following steps: Emitting (1110), having a transmitter, a transmit signal having a first polarization direction; Receiving (1120) the transmission signal and transmitting, with a signal reflector, a response signal having a second polarization direction different from the first polarization direction, based on the received transmission signal; Receiving (1130) the response signal with a receiving device and determining the distance between the signal reflector and the transmitting device or the receiving device based on a phase position of the response signal with respect to the transmission signal.

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