Magneto-elastic sensor, load pin, ball-joint and tow coupling comprising this sensor, method of determining a direction of a load vector

A magneto-elastic sensor comprising:

• a longitudinally extending shaft like member, which is subject to a load introducing mechanic stress in the member,
• at least one magneto-elastically active region directly or indirectly attached to or forming a part of the member in such a manner that the mechanic stress is transmitted to the active region, said active region comprising at least one magnetically polarized region such that the polarization becomes increasingly helically shaped as the applied stress increases;
• a magnetic field sensor means arranged approximate the at least one magneto-elastically active region for outputting a signal corresponding to a stress-induced magnetic flux emanating from the magnetically polarized region;
• the magnetic sensor means comprising at least one direction sensitive magnetic field sensor, which is configured for determination of at least one out of a shear stress and a compressive stress, wherein the magnetic field sensors are arranged to have a predetermined and fixed spatial coordination with the member,
• wherein the member comprises a first magneto-elastically active region and a second magneto-elastically active region, which are directly or indirectly attached to or form a part of the member in such a manner that the mechanic stress is transmitted to the active regions, each active region comprising a magnetically polarized region, wherein the magnetic polarization of the first active region and the magnetic polarization of the second active region are substantially opposite to each other, and wherein the magnetic sensor means comprises a first pair of magnetic sensors comprising a first and a second magnetic field sensor being arranged approximate the first magneto-elastically active region for outputting a first signal corresponding to a stress-induced magnetic flux emanating from the first magnetically polarized region and the magnetic sensor means comprises a second pair of magnetic sensors comprising a first and a second magnetic field sensor being arranged approximate the second magneto-elastically active region for outputting a second signal corresponding to a stress-induced magnetic flux emanating from the second magnetically polarized region, wherein the magneto-elastic sensor further comprises a control unit, which is configured for determination of the stress applied to the member by performing a differential evaluation of the signals of the first pair of sensors and the second pair of sensors.

A method of determining a direction of a load vector, the method comprising the steps of:

• providing a magneto-elastic sensor comprising:
• a longitudinally extending shaft like member, which is subject to the load introducing mechanic stress in the member;
• at least one magneto-elastically active region directly or indirectly attached to or forming a part of the member in such a manner that the mechanic stress is transmitted to the active region, said active region comprising at least one magnetically polarized region such that the polarization becomes increasingly helically shaped as the applied stress increases;
• a magnetic field sensor means arranged approximate the at least one magneto-elastically active region for outputting a signal corresponding to a stress-induced magnetic flux emanating from the magnetically polarized region;
• wherein the magnetic sensor means comprises at least one direction sensitive magnetic field sensor, which is arranged to have a predetermined and fixed spatial coordination with the member,
• exposing the longitudinally extending shaft like member to the load,
• processing measurement data of the at least one direction sensitive magnetic field sensor so as to determine at least one out of a shear stress and a compressive stress, so as to determine a direction of the load vector from the measurement data and the predetermined and known spatial coordination between the direction sensitive magnetic field sensor and the member,
• wherein the sensor means comprises at least a first to fourth magnetic field sensor having a first to fourth sensing direction, wherein the sensing directions and a shaft axis are at least substantially parallel to each other, and wherein the first to fourth magnetic field sensor are arranged along the circumference of the shaft having substantially equal distances in circumferential direction between each other, the method further comprising the steps of:
• processing measurement data of the first and third magnetic field sensor so as to determine a first component of a load vector and
• processing measurement data of the second and fourth magnetic field sensor so as to determine a second component of the load vector,
• determining a direction of the load vector, which impacts the longitudinally extending shaft like member, from the determined first and second component and the predetermined and known spatial coordination of the first to fourth magnetic field sensor with respect to the member.

A method of determining a direction of a load vector, the method comprising the steps of:

• providing a magneto-elastic sensor comprising:
• a longitudinally extending shaft like member, which is subject to the load introducing mechanic stress in the member;
• at least one magneto-elastically active region directly or indirectly attached to or forming a part of the member in such a manner that the mechanic stress is transmitted to the active region, said active region comprising at least one magnetically polarized region such that the polarization becomes increasingly helically shaped as the applied stress increases;
• a magnetic field sensor means arranged approximate the at least one magneto-elastically active region for outputting a signal corresponding to a stress-induced magnetic flux emanating from the magnetically polarized region;
• wherein the magnetic sensor means comprises at least one direction sensitive magnetic field sensor, which is arranged to have a predetermined and fixed spatial coordination with the member,
• exposing the longitudinally extending shaft like member to the load, processing measurement data of the at least one direction sensitive magnetic field sensor so as to determine at least one out of a shear stress and a compressive stress, so as to determine a direction of the load vector from the measurement data and the predetermined and known spatial coordination between the direction sensitive magnetic field sensor and the member,
• wherein the member comprises a first magneto-elastically active region and a second magneto-elastically active region, which are directly or indirectly attached to or form a part of the member in such a manner that the mechanic stress is transmitted to the active regions, each active region comprising a magnetically polarized region, wherein the magnetic polarization of the first active region and the magnetic polarization of the second active region are substantially opposite to each other, and wherein the magnetic sensor means comprises a first pair of magnetic sensors comprising a first and a second magnetic field sensor being arranged approximate the first magneto-elastically active region for outputting a first signal corresponding to a stress-induced magnetic flux emanating from the first magnetically polarized region and the magnetic sensor means comprises a second pair of magnetic sensors comprising a first and a second magnetic field sensor being arranged approximate the second magneto-elastically active region for outputting a second signal corresponding to a stress-induced magnetic flux emanating from the second magnetically polarized region, the method further comprising the step of:
• performing a differential evaluation of the signals of the first pair of sensors and the second pair of sensors so as to determine the stress applied to the member.