The present invention relates to a diagnostic system for continuous detection of cord defects in flat steel-plastic ropes to be used particularly for the purpose of operating inspection of passenger elevators and goods lifts as well as conveyor belts reinforced with steel cords and circular cross-section cables used in cableway transport systems.

Recent development in the vertical transport technology resulted in introduction of systems eliminating the upper machinery room and employing ropes in the form of flat bands made of steel cords arranged in parallel and fixed with respect to each other by means of covering them with an elastic plastic, typically polyurethane. In the year 200, OTIS company has introduced an new solution for passenger elevator drive systems known as Gen2, using a gearless power winch and steel-polyurethane ropes in the form of 3 mm-thick tension bands with 12 cords, each 1.5 mm in diameter and made of 7 strands spliced in turn of 7 zinc-plated steel wires with diameter of 0.175 mm and embedded in polyurethane. Safety regulations applicable to rope-based transport systems impose special requirements in scope of particularly careful inspection concerning condition of their load-carrying components. The solution revealed in the European patent application EP2299251 uses the magnetic energy for diagnosing degradation of cords in flat steel- plastic ropes. The measuring head has permanent magnets that generate continuously, as the belt- shaped rope moves, a constant magnetic field with its circuit being closed through steel cords along the rope section between longitudinally deployed N-S poles. The measurement of variations in the magnetic field intensity taken by the detector directly over the N-S region provides a picture of homogeneity and continuity of the rope's internal ferromagnetic structure through which the magnetic field lines are being closed. The head comprises a number of measuring systems assigned to each of the cords such that signals from detectors of those individual systems are electronically processed, successively, in a signal processing block and an analyser, and then registered in a data carrier. The results allows to determine technical condition of the rope with possibility to identify, by means of an encoder, the location in which the tension strength of the rope is deteriorated. Similar measuring system is employed in solution presented in description of Polish patent application PL207764 designed for on-line monitoring and location of defects in a reinforced belt lapping joints of a long conveyor composed of a large number of sections connected to each other with their ends by means of vulcanisation or adhesive bonding. Solutions with heads generating permanent magnetic field and the circuit being closed along the rope are difficult to integrate in conditions where a belt-shaped rope's width is in the range 30-60 mm with small distance typically maintained between them.

The system for continuos detection of cord defects in flat steel-plastic elevator ropes according to the present invention is provided, just like as in the solution described above, with an integrated measuring head comprising a magnetic filed source and a field intensity sensor, a signal processing block, a signal analyser, and a data storage. The essence of the solution consists in that the measuring head comprises a variable magnetic field pulse inductor and a stray field detector situated over the surface and deployed along the cords along direction of motion of the rope one by one at a small distance from each other.

The measuring head encompasses preferably the whole width of the rope, giving thus, in the above-described operating conditions, a result representing the local tension strength for the whole rope length.

In particularly difficult operation conditions, wireless transmission of data between the signal processing block and the analyser, and possibly also between the analyser and the data carrier may turn out to be a preferable solution.

In the system according to the present invention, a defect is represented by a variation of intensity of stray field induced around the cords in the zone directly adjacent to the location where pulsed magnetic field variations occur. The assumed small distance between the stray field detector and the inductor is a guarantee for high damage detectability. At the same time, analysis of the detector's signal converted into information on field pulsation resulting from periodic structure of strands allows to determine the rope velocity thus eliminating the need of using an encoder.

The invention is illustrated below by an example embodiment of the system for continuos detection of cord defects in flat steel-polyurethane rope presented schematically in the figure.

The system comprises a measuring head with a pulse inductor (1) of variable magnetic field and the detector (2) of stray field (5) mounted directly one by one at a small distance (AL) from each other along cords (4) and along direction of motion (V) of rope (3). The inductor (1) may be of eddy current or induction type, while the detector (2) contains measuring elements reacting to magnetic field intensity variations, preferably a Hall effect sensor or a thin film element. At a small distance (AL), magnetic field generated by inductor (1) maintains intensity guaranteeing effective operation of detector (2) resulting in detection of flaws in cords (4) constituting the steel structure of rope (3). The signal from detector (2) representing variations of stray field (5) generated by a decrease of cross-section area of cords (4) is transferred to the signal processing block (6) and, after filtration, further to the signal analyser (7). Measuring zone of the head covers the whole width of rope (3), and the result defining indirectly the local tension strength of rope (3) is compared to a nominal reference level value. Results of inspection concerning technical condition of rope (3) are registered in a database stored in data carrier (9) and may be presented graphically if necessary.