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EP-4735854-A1 - NORMAL STRESS SENSOR SYSTEM

EP4735854A1EP 4735854 A1EP4735854 A1EP 4735854A1EP-4735854-A1

Abstract

The invention relates to a normal stress sensor system comprising: at least one normal stress sensor (1) with a force measuring disc (16) with a resonator (13c) having a first natural frequency dependent, preferably at least substantially linearly, on a mechanical normal stress to be detected, wherein the force measuring disc (16) is designed as a disc perpendicular to the longitudinal axis (X), wherein the resonator (13c) is embedded in the force measuring disc (16) in an annular shape around the longitudinal axis (X), and wherein the force measuring disc (16) and the resonator (13c) are designed to be compressible and radially expandable along the longitudinal axis (X); and comprising an antenna (15) that surrounds the edge of the annular resonator (13c) of the force measuring disc (16) in an arcuate manner at least in sections, wherein the antenna (15) is spaced radially apart from the edge of the annular resonator (13c) of the force measuring disc (16) by a distance (14), and wherein the resonator (13c) and the antenna (15) are designed so that normal mechanical stresses (F) acting on the force measuring disc (16) change the natural frequency of the resonator (13c); and comprising at least one control unit (2) designed to excite the resonator (13c) of the normal stress sensor (1) by means of its antenna (15) to oscillate at its natural frequencies, to detect the resonant oscillations of the resonator (13c) of the normal stress sensor (1) by means of its antenna (15), and to determine the mechanical normal stresses (F) from the detected resonant oscillations of the resonator (13c).

Inventors

  • RECK, SIEGFRIED

Assignees

  • ContiTech Deutschland GmbH

Dates

Publication Date
20260506
Application Date
20240610

Claims (15)

  1. 1. Normal stress sensor system with at least one normal stress sensor (1) with a force measuring disk (16) with a resonator (13c) with a first natural frequency, which is dependent on a mechanical normal stress to be detected, preferably at least substantially linearly, wherein the force measuring disk (16) is designed as a disk perpendicular to the longitudinal axis (X), wherein the resonator (13c) is embedded in the force measuring disk (16) in a ring shape around the longitudinal axis (X), and wherein the force measuring disk (16) and the resonator (13c) are designed to be compressible and radially expandable along the longitudinal axis (X), and with an antenna (15) which surrounds the edge of the ring-shaped resonator (13c) of the force measuring disk (16) in an arc shape at least in sections, wherein the antenna (15) is radially spaced from the edge of the ring-shaped resonator (13c) of the force measuring disk (16) by a distance (14) is spaced apart, and wherein the first resonator (13c) and the antenna (15) are designed so that mechanical normal stresses (F) acting on the force measuring disk (16) change the natural frequency of the resonator (13c), and with at least one control unit (2) which is designed to excite the resonator (13c) of the normal stress sensor (1 ) by means of its antenna (15) to oscillate at its natural frequencies, to detect the resonance oscillations of the resonator (13c) of the normal stress sensor (1 ) by means of its antenna (15), and TI to determine the mechanical normal stresses (F) from the recorded resonance vibrations of the resonator (13c).
  2. 2. Normal voltage sensor system according to claim 1, wherein the resonator (13c) is part of a microwave stripline (13).
  3. 3. Normal voltage sensor system according to claim 1 or 2, wherein the resonator (13c) is designed as a high-frequency resonator (13c).
  4. 4. Normal voltage sensor system according to one of the preceding claims, wherein the resonator (13c) has a conductive structure which is designed to oscillate at a fundamental frequency between 0.1 GHz and 6 GHz.
  5. 5. Normal voltage sensor system according to one of the preceding claims, wherein the resonator (13c) is flanked along the longitudinal axis (X) on both sides by conductive surfaces (13d, 13e) which complement the resonator (13c) to form a first microwave stripline (13).
  6. 6. Normal voltage sensor system according to claim 5, wherein the antenna (15) is a second microwave stripline (15).
  7. 7. Normal voltage sensor system according to claim 5 or 6, wherein the conductive surfaces (13d, 13e) comprise a Ni-Cr alloy, preferably consist thereof.
  8. 8. Normal stress sensor system according to one of the preceding claims, wherein the antenna (15) and the resonator (13c) of the force measuring disk (16) are arranged directly radially opposite each other.
  9. 9. Normal stress sensor system according to one of the preceding claims, wherein the antenna (15) is arranged on a transmission ring (17) which at least substantially, preferably completely, surrounds the resonator (13c) of the force measuring disk (16) in the circumferential direction.
  10. 10. Normal voltage sensor system according to claim 9, wherein the remaining surface on the inside of the transmission ring (17) and its outer surface are metallized and electrically connected to the reference potential of a control unit (2).
  11. 11. Normal stress sensor system according to one of the preceding claims, wherein the distance (14) between antenna (15) and resonator (13c) of the force measuring disk (16) is at least partially, preferably completely, filled with an elastic, preferably elastomeric, material which connects the antenna (15) and the resonator (13c) to one another.
  12. 12. Normal stress sensor system according to one of the preceding claims, wherein the force measuring disk (16) is made of high-strength, preferably ceramic, material.
  13. 13. Normal voltage sensor system according to one of the preceding claims, wherein the control unit (2) is designed to computationally compensate for the influence of the temperature.
  14. 14. Normal voltage sensor (1) for use in a normal voltage sensor system according to one of claims 1 to 13.
  15. 15. Control unit (2) for use in a normal voltage sensor system according to one of claims 1 to 13.

Description

Description normal voltage sensor system The present invention relates to a normal voltage sensor system according to claim 1, a normal voltage sensor for use in such a normal voltage sensor system according to claim 14 and a control unit for use in such a normal voltage sensor system according to claim 15. In order to measure mechanical normal and shear stresses, the measuring transducers must be integrated into the component in such a way that they can record the force flow to be measured. If this force flow is inhomogeneous, flat sensors are usually required. Elastomer-based pressure measuring foils, which are inserted into the component for one measurement at a time, map the distribution of the maximum stresses that have occurred through color changes. However, this is usually inaccurate, cannot be recorded electronically, and an unused pressure measuring foil must be installed, removed and evaluated for each measurement, which makes this type of recording of normal and shear stresses unattractive. With the help of electronic pressure measuring foils, normal stress distributions can be measured continuously and electronically. For example, a matrix of piezoresistive transducers provides the data for a spatially resolved image. Alternatively, dielectric elastomer sensors (DES) can be suitable for measuring mechanical normal stresses. However, with the exception of dielectric elastomer sensors, such known sensors are only partially suitable for measuring mechanical stresses in elastomer bodies because the dielectric elastomer sensors cannot follow relatively large strains. In addition, piezoresistive pressure measuring films are expensive, so they are preferably used for discontinuous measurements. From DE 10 2020 216 234 A1 a device for detecting mechanical normal stresses in an elastomer component is known, with an elastomer component, with at least one normal stress sensor, wherein the normal stress sensor has at least one resonator whose natural frequency is dependent on the mechanical normal stresses to be detected, preferably at least substantially linearly, wherein at least the resonator is embedded in the elastomer component in such a way that mechanical normal stresses acting on the elastomer component can change the natural frequency of the resonator, and with at least one control unit which is designed to excite the resonator to oscillate at its natural frequency and to detect its oscillations, wherein the control unit is further designed to determine the mechanical normal stresses of the elastomer component from the detected oscillations of the resonator. In other words, a normal force sensor for elastomeric components is described, which consists of a so-called symmetrical microwave strip line, which is designed as a resonator. Along the longitudinal axis above and below a conductor strip there is a dielectric, which is covered on its outer surface with a conductive layer and is electrically at ground potential. The normal force to be measured compresses the strip line along the longitudinal axis and thus reduces the distance between the centrally arranged conductor strip and the two outer ground surfaces along the longitudinal axis, which changes the wave impedance and the return loss of the arrangement. When measuring the force, the Stripline connected to an impedance spectrometer, which evaluates the wave impedance and the return loss and calculates the measurement result. A disadvantage of the device of DE 10 2020 216 234 A1 is that in this way only the average normal stress can be detected, which acts in the middle of the surface of the normal stress sensor. From DE 10 2021 206 816 A1 a normal stress sensor system is known with at least one normal stress sensor with at least one first resonator with a first natural frequency which is dependent on a mechanical first normal stress to be detected, with at least one second resonator with a second natural frequency which is dependent on a mechanical second normal stress to be detected, wherein the normal stress sensor is designed to be arranged between two objects in such a way that mechanical normal stresses acting between the objects can change the natural frequencies of the resonators, and with at least one control unit which is designed to excite the resonators of the normal stress sensor to oscillate at its natural frequencies and to detect its oscillations, wherein the control unit is further designed to determine the mechanical normal stresses from the detected oscillations of the resonators. In the normal voltage sensor of DE 102021 206 816 A1, there is a resonant conductor structure between two conductive surfaces that are electrically at ground potential. The space between the resonator and the ground surfaces is filled with an elastomeric dielectric. The applications in which the normal voltage is to be measured by sensors will include future braking systems in which the hydraulic components used to date are to be replaced by ele