The present invention relates to a screw nut equipped with sensors (2, 3) on its lateral surfaces.

A bolt includes a head portion on which a recess is formed. The recess has a bottom surface and a sidewall extending from a periphery of the bottom surface. The sidewall has a lower end defined by the bottom surface and includes an increased diameter portion and a reduced diameter portion. The increased diameter portion has an inner diameter larger than an inner diameter of the lower end of the side wall. The reduced diameter portion has an inner diameter smaller than the inner diameter of the increased diameter portion. The reduced diameter portion is located opposite to the bottom surface across the increased diameter portion.

Fixing device comprising a fixing member provided with a bearing head, a sensor provided with a detector of the mechanical force to which the fixing member is subjected, the detector being mounted in contact with the fixing member, and a connecting component which is electrically connected to the sensor, which is configured to transmit a measurement of a mechanical force provided by the sensor and which is mounted on the fixing member, the fixing member comprising a body which is mounted on the bearing head and which extends along a longitudinal axis protruding from the bearing head.

A tag configured to detect loosening of a fastening member fastened to a fastened part of an apparatus includes: a base sheet including a fastening member attached portion and a fastened part attached portion, the fastening member attached portion being attached to the fastening member, the fastened part attached portion being attached to the fastened part; a RFID chip mounted on the base sheet; an antenna circuit mounted on the base sheet while being connected to the RFID chip; and an electric conductor mounted on the base sheet while being connected to the RFID chip, the electric conductor being configured such that an electric property of the electric conductor changes when the fastening member is displaced relative to the fastened part attached portion.

A looseness detection sensor for detecting looseness of a bolt for fixing a component, including: a resonance unit arranged adjacent to a head portion of the bolt and made of an insulating material confining a high-frequency signal input externally; and a conductive member in conduction with the component across the resonance unit, wherein the conductive member is a cap put on the head portion of the bolt and includes a protrusion contacting a surface of the component.

A fastener and a system, apparatus, and method for monitoring a fastener are described. The fastener includes a head portion, a shank portion, a transponder, and a compression spring, wherein the head portion includes a mounting portion, and wherein the transponder is disposed in the mounting portion of the head portion. The transponder is arranged to monitor the shank portion, and includes an ultrasonic sensor and a signal processing circuit. The ultrasonic sensor is affixed to a transducer hosting surface, and is urged against the transducer hosting surface by placement of the printed circuit board in the head portion with the compression spring intervening therebetween. The ultrasonic sensor communicates with the signal processing circuit via the compression spring. The signal processing circuit captures a signal from the ultrasonic sensor and transforms the signal into a parameter corresponding to a tensile force being exerted by the fastener.

The invention relates to a solution for how to measure the strain in a washer mounted in a bolt assembly comprising a bolt, nut and washer. The invention concerns a strain measuring washer assembly comprising a plate shaped washer body, sound emitting means and sound detecting means, and a method for using such.

A nut, or a washer for a nut, in particular a wheel nut or axle nut for vehicles, having a body, having a central threaded hole, having a peripheral wall, having an abutment face at a lower side, wherein the nut also has a plurality of wrench faces on the peripheral wall of the nut body for tightening or releasing the nut by means of a tool which cooperates with the wrench faces. In order to be able to detect the loosening of wheel nuts or axle nuts of vehicles, and to indicate such loosening to a vehicle driver to avoid dangerous situations during driving, there is provided in the body at least one recess in which a sensor element is arranged, wherein the sensor element is connected to a wireless interface which is configured to transmit a sensor signal of the sensor element wirelessly to an external reception unit.

There is provided a sensor unit for a fastener assembly, the sensor unit comprising a mounting arranged to rigidly attach the sensor unit to, or adjacent to, a fastener assembly; and a sensor, that is an optical flow sensor or an inductive sensor, configured to sense movement of the fastener assembly. The sensor unit may comprise a processor arranged to process the output of the sensor to detect loosening of the fastener assembly and to output a signal representing the status of the fastener assembly. The sensor unit may comprise a wireless communication unit arranged to communicate the signal.

A clamping element comprises a clamping body, such as a screw, having an ultrasound sensor fixed to the head. The sensor transmits and collects ultrasound that propagates along the shaft of the screw between two flat and parallel base surfaces, to measure a physical quantity connected to the clamping force that acts on the screw. A cap-shaped cover element can be removably affixed to the screw head and houses a wired or wireless communication module, a controller, power supply means, and possibly additional sensors. A memory can be stably fixed to the ultrasound sensor to store screw-characteristic data. A monitoring system can collect and process the data of all the clamping elements with a single processor.