Background of the invention

The invention relates to a load-bearing component of an elevator. The component is provided with one or more 5 strain gauges and is subjected to forces and stresses during use of the elevator.

The invention further relates to an elevator and method for monitoring operation of an elevator.

The field of the invention is defined more specif ic) ically in the preambles of the independent claims.

In elevators there are different needs to sense loadings directed to mechanical structures of the elevator. Forces, stresses, and material fatigues can be measured by means of a strain gauge. The strain gauges are typically so 15 called foil strain gauges comprising long, thin conductive strips in zig-zag patterns of parallel lines. The strain gauges can be attached on monitored objects by suitable adhesives. As the object is deformed due to stresses, the foil is deformed, causing its electrical resistance to 20 change. This resistance change is related to the strain and can be calculated in a control unit, for example. However, the known solutions have shown to contain some disad vantages .

Brief description of the invention

25 An object of the invention is to provide a novel and improved load-bearing element, an elevator and a method for monitoring the elevator.

The load-bearing element according to the invention is characterized by the characterizing features of the first 30 independent apparatus claim.

The elevator according to the invention is charac terized by the characterizing features of the second inde pendent apparatus claim. The method according to the invention is character ized by the characterizing features of the independent method claim.

An idea of the disclosed solution is that a load- bearing component of an elevator is provided with one or more printed strain gauges for sensing strain on the com ponent. In other words, the strain gauge arranged on the component is manufactured by the methods of printed elec tronics. Thus, the strain gauge serves as a load weighting device and comprises one or more printed circuit boards (PCB).

An advantage of the disclosed solution is that the printed strain gauge and related auxiliaries are cheaper and easier to manufacture and to install than the known foil strain gauges. The printing suits well for low-cost volume fabrication, and on the other hand, it allows an easy way to adjust the strain gauges for different purposes and lo cations in the elevator use. Further, the printed strain gauges can be produced and delivered flexibly. Due to the printing technology, the strain gauges may be small sized, and they can be arranged on nearly any surface shape and size.

According to an embodiment, the disclosed solution can be utilized determining weight of cargo inside an ele- vator car. The system can also be used for the purpose of structural health monitoring and needs of preventive mainte nance, for example.

According to an embodiment, the strain gauge is printed on at least one substrate and the substrate is attached on an outer surface of the component by gluing agent, or in any other suitable fastening element or manner.

According to an embodiment, the strain gauge is formed directly on an outer surface of the component being monitored by means of additive manufacturing technology. In other words, the strain gauge can be manufactured directly on planar and even non-planar surfaces, by means of 3-D printing, for example.

According to an embodiment, the strain gauge is provided with a printed connecting wiring for communicating with at least one control unit or with a communication unit providing required data transmission with the control unit.

According to an embodiment, the strain gauge is connected to at least one wireless data communication device for communicating with at least one control unit. According to an embodiment, in connection with the printed strain gauge there is also at least one antenna for wireless connectivity. This way the strain gauge may be provided with means utilizing WiFi™, NFC or other data com munication protocols. According to an embodiment, the strain gauge is provided with a RFID tag for providing the strain gauge with a passive radio frequency identification (RFID), whereby the strain gauge attached on the surface of the component is remotely communicated and powered by an external trans- mitter. In this solution not only the strain gauge but also the RFID tag is a printed circuit board.

According to an embodiment, the RFID-based technol ogy allows the strain gauge to be passive, i.e. operate without other power source such as batteries or cables. This is possible since the RFID tag is capable of harvesting electromagnetic power from the communication signal emitted by an antenna of the RFDI reader. Then the strain gauge itself does not require other (internal) power sources and thus, serves as a battery less (passive) and wireless strain sensor.

According to an embodiment, the RFDI reader may be a handheld or portable electronic device which can be used by maintenance personnel, for example.

According to an embodiment, the RFID reader may be mounted to the structure of the elevator. Then the sensing device comprising the printable strain gauge and the RFID tag may be mounted on a movable component of the elevator and the RFID reader may activate the passive sensing device and communicate with it when the sensing device passes the RFIF reader transmitting signals by its antenna. This way, monitoring data may be gathered from the sensor each time when the RFID tag is inside a detection range of the RFID reader.

According to an embodiment, there may be two or more RFID readers or antennas for gathering data from the strain gauge, whereby the sensing data can be received at two or more vertical locations of the car, for example. It is also possible that the same RFID reader or antenna can communi cate with two or more different strain gauges provided with the RFID tags. According to an embodiment, the printed strain gauge is provided with one or more additional printed electronic components or circuits. The additional components may re late to communication technology or they may be additional sensing components. Thus, in connection with the printed strain gauge there may be one or more pressure sensors, acceleration sensors, temperature sensors or any other printable sensors for sensing physical properties and cir cumstances.

According to an embodiment, the printed strain gauge is provided with printed collector elements for providing it with electrical connecting means which allow the printed system to communicate with other electrical devices, wir ings or systems.

According to an embodiment, the load-bearing compo- nent is a rope fixing assembly for fixing at least one suspension rope of the elevator. The rope fixing assemblies are utilized for different types suspension ropes, hoisting ropes, and traction ropes.

According to an embodiment, the load-bearing compo- nent is a rope fixing assembly for fixing at least one suspension rope to an elevator car. According to an embodiment, the load-bearing compo nent is a rope fixing assembly for fixing at least one suspension rope to a counterweight assembly. According to an embodiment, the load-bearing compo nent is a rope fixing assembly for fixing at least one suspension rope to a fixed structure of the elevator. The rope fixing assembly may then serve as an anchoring point for ends of one or more suspension ropes. This kind of rope fixing assembly may also be called an anchoring element.

According to an embodiment, the load-bearing compo nent is a suspension rope, or an intermediate element mounted between an end of the suspension rope and a fixing point of the suspension rope. According to an embodiment, the load-bearing compo nent is a mechanical element of a hoisting machinery.

According to an embodiment, the load-bearing compo nent is a topmost suspension beam of an elevator car. Al ternatively, the load-bearing component may be any other structural component configured to provide vertical support for the car assembly.

According to an embodiment, a traction rope is uti lized in an elevator wherein a hoisting machinery is located at a bottom part of an elevator shaft. Then the traction rope is a load-bearing component and may be provided with one or more strain gauges which are in accordance with this document.

According to an embodiment, a compensation element, such as a compensation rope or chain, may be subjected to forces during the operation of the elevator. Then the com pensation element may be considered to be a load-bearing component and may be provided with one or more strain gauges which are in accordance with this document. The generated data can used for generating data on condition of the com pensation element, for example. According to an embodiment, the load-bearing ele ment is any element of the elevator that needs to be moni tored because it is subjected to stresses during the use of the elevator. Thus, the disclosed strain gauge may belong to a preventive maintenance system of the elevator. Since the printable strain gauges are low-cost and small in size, it is possible to implement them widely and thereby gather valuable sensing data for not only for controlling the maintenance but also for controlling operation of the ele- vator too. In other words, the printed strain gauge may be arranged to monitor any point of interest (POI) in the elevator.

According to an embodiment, the strain gauge is manufactured by ink-jet printing (IJP) technology. The IJP is a low cost method and easy to implement almost anywhere.

According to an embodiment, the printed strain gauge is ink-jet printed by using ink comprising silver, copper, or carbon.

According to an embodiment, the sensor structure is applied directly on surface of the monitored component with the help of ink-jet printing technology.

According to an embodiment, the strain gauge is screen printed on a substrate with carbon paste, for exam ple. According to an embodiment, the strain gauge is aerosol printed on a substrate by using silver nanoparticle ink. This technology is called an Aerosol jet-printing.

According to an embodiment, the printed strain gauge comprises a substrate which may made be of flexible foil, such as thin aluminum. Alternatively, the substrate may be a plastic film, for example. The strain gauge may be printed on a flexible substrate whereby the structure may be flex ible and can be bent into desired shapes. This the strain gauge may be mounted not only on flat but also on curved surfaces. According to an embodiment, the printed strain gauge comprises an encapsulation to protect the printed sensor. Thus, there may be one or more plastic films of other pro tective layers on the printed electric circuits. According to an embodiment, the disclosed solution relates to an elevator comprising: an elevator car; at least one first guide assembly provided with first vertical guide rails mountable to the elevator shaft and first guide shoes mountable to the car assembly, and wherein the guide shoes are supportable against the guide rails; a hoisting machin ery for moving the car vertically inside an elevator shaft; and one or more strain gauges configured to monitor one or more load-bearing components of the elevator. The mentioned one or more strain gauges are in accordance with any one of the features and embodiments disclosed in this document.

According to an embodiment, the elevator is a trac tion elevator and comprises: a counterweight assembly pro vided with a counterweight frame and at least one filler element; a second guide assembly provided with second ver- tical guide rails and second guide shoes for the counter weight frame and wherein the mentioned guide shoes are sup portable against the guide rails; a hoisting machinery com prising an electric motor and a traction sheave driven by means of the electric motor; and at least one suspension rope connecting the car and the counterweight assembly and arranged to pass over the traction sheave. One or more printed strain gauges are mounted to one or more load bear ing components which are subjected to stresses caused by cargo inside the car. According to an embodiment, the traction elevator is a machine room less elevator.

According to an embodiment, the elevator may alter natively be a hydraulic elevator, or any other type of an elevator. According to an embodiment, the printed strain gauge is mounted to a load bearing component being part of a movable structure of the elevator. The printed strain gauge assembly may be provided with one or more remote readable tags. Then a fixed structural part of the elevator may be provided with one or more antennas for remotely activating the printed strain gauge for providing sensing data and activating the tag for transmitting sensing data in response to situation when tag is inside a range of the antenna. The electric waves transmitted by the antenna provides the strain gauge with required electric power for executing the sensing measures.

According to an embodiment, the disclosed solution relates to a method of monitoring operation of an elevator. The method comprises: providing one or more load-bearing components of the elevator with one or more strain gauges; and producing sensing data by means of the strain gauge and transmitting the sensing data to one or more control units for further processing. The method further comprises provid ing the mentioned one or more load-bearing components with one or more printed strain gauges. According to an embodiment, the method comprises controlling operation of the elevator in response to the produced sensing data of the strain gauge.

According to an embodiment, the method comprises utilizing the produced sensing data in operations of a pre- ventive maintenance.

According to an embodiment, the method may further comprise: implementing the printed strain gauge as a load weighting device (LWD) of the elevator and examining load of cargo inside a car of the elevator in at least one control unit in response to sensing data gathered from the printed strain gauge.

Let it be mentioned that in this document the term "suspension rope" may refer to different type of rope sys tems and their suspension ropes, hoisting ropes and traction ropes. The above disclosed embodiments may be combined in order to form suitable solutions having those of the above features that are needed.

Brief description of the figures Some embodiments are described in more detail in the accompanying drawings, in which

Figure 1 is a schematic and highly simplified side view of a traction elevator,

Figure 2 is a schematic and highly simplified par- tial side view of another traction elevator,

Figure 3 is a schematic side view of a rope fixing assembly or anchoring provided with a load weighting ar rangement,

Figure 4 is a schematic side view of a system for remote reading data on a printed strain gauge,

Figure 5 is a schematic diagram of some possible load-bearing components which may be equipped with printed strain gauges,

Figure 6 is a schematic diagram of a strain gauge assembly and its possible printed components,

Figure 7 is a schematic top view of a printed strain gauge and its components, and

Figure 8 is a schematic top view of a strain gauge provided with wireless connectivity. For the sake of clarity, the figures show some em bodiments of the disclosed solution in a simplified manner. In the figures, like reference numerals identify like ele ments.

Detailed description of some embodiments Figure 1 discloses a traction elevator 1 mounted to an elevator shaft 2 of a building. The elevator 1 comprises an elevator car 3 for receiving load to be transported. The car 3 and a counterweight assembly 4 are suspended form a suspension rope 5 passing via a hoisting machinery 6. The hoisting machinery 6 comprises a traction sheave 7 driven by means of an electric motor M. Between the suspension rope 5 and the traction sheave 7 occurs friction which is uti lized for transmitting lifting power to the elevator system. The hoisting machinery 6 may comprise one or more additional pulleys 8 for guiding and controlling the suspension rope 5. Further, different rope schemas and ratios may also be implemented. The roping ratio may be 1:1, 1:2 or 1:4, for example. The hoisting machinery 6 may be located at an upper machine room 9, or alternatively the system may be a so called machine room less elevator. The car 3 can be driven to desired levels 10 or floors under control of one or more control units CU. Further, at a bottom of a pit 10 of the shaft 2 are buffers 11a, lib. The buffer 11 is a device configured to stop the descending car 3 and the counter- weight 4 beyond its normal limit. The buffer 11 is arranged to soften the forces with which the elevator 1 runs into the pit 12 during special situations. Further, the bottom of the car 3 and a bottom of the counterweight assembly 4 are connected by means of a compensation element 13, such as a chain, rope or belt. The compensation element 13 may pass via a compensator pulley 14 located at the pit.

The disclosed solution utilizing printed strain gauges can be implemented in a versatile manner at different load-bearing structures and components of the elevator. A frame structure of the elevator car 3 may comprise a topmost suspension beam 15 configured to support the frame vertically. Thus, the suspension beam 15 serves as a load- bearing component 16, which may be provided with the dis closed printed strain gauges. Alternatively, the frame structure may comprise one or more other type of support elements with any other shapes than the beam. Further, there may be a rope fixing assembly 17 for fixing the suspension ropes 5 to the car 3. Then, the rope fixing assembly 17 serves as the load-bearing component 16 and may be monitored by means of one or more printed strain gauges. There may be another rope fixing assembly 18 at the counterweight assem bly 4 and it can also be equipped with the printed strain gauges.

Further, it is possible to provide the compensation element 13 with one or more printable strain gauges for producing data for preventive maintenance solutions, for example.

In an embodiment of the solution disclosed in Figure 1, the sheave 7 may be a freely rotating sheave and the compensator sheave 14 of Figure 1 may be substituted with a traction sheave and traction motor assembly. Then the compensation rope 13 is substituted with a traction rope. The traction rope and its mounting assemblies may be pro vided with one or more disclosed printed strain gauges. In Figure 2 one or more suspension ropes 5 are an chored to the fixed structure of a traction elevator 1 by beans of an anchoring element 19, which is another type of a rope fixing assembly and it serves as a load-bearing component 16. The anchoring element 19 may be provided with the disclosed pintable strain gauges. Alternatively, or in addition to, a car side rope fixing assembly 17 may be provided with the pintable strain gauges. The rope fixing assembly 17 may support a pulley. Further, there may be another anchoring element 19a or rope terminal for fixing the one or more ropes 5. The element 19a may be provided with one or more strain gauges which are in accordance with the features disclosed in this document. Thus, there may be one, two or three disclosed load-bearing components 16 in this solution. For clarity reasons the printed strain gauges are not shown in Figures 1 and 2.

Figure 3 discloses an anchoring element 19 for fas tening suspension ropes 5 to a vertical structure 20 of an elevator. The anchoring element 19 may serve not only as a load-bearing component 16 but also as a load weighting de vice or unit. Weight W of cargo inside an elevator car 3 pulls a weighting frame 21 downwards via the ropes 5 and causes bending on a top part 22 of the weighting frame 21. There are one or more printed strain gauges 23 or strain gauge assemblies arranged on a top surface of the top part 22 which can sense the bending and extension on the top surface. Generated sensing data is transmitted to one or more control unit and the weight of the cargo can be cal culated.

Further, the structure 21 may alternatively be mounted to a top part of an elevator shaft.

Figure 4 discloses an arrangement wherein a rope fixing assembly 17 on top of an elevator car 3 is provided with a printed strain gauge 23 and a printed RFID tag 24. When the elevator car 3 moves up and down, it passes an antenna 25 mounted immovably to frame structures of the elevator or to an elevator shaft. The antenna 25 has a reading range 26 and when the RFID tag 24 is at reach of the reading range 26, then communication is formed between the tag and the antenna, and data transmission is possible. The antenna 25 may also provide the strain gauge 23 with the required electric energy so that the printed chip or circuit can be without any own electric energy storage. This way, the strain gauge assembly can be energized and read each time the elevator car 3 passes the antenna 25 and weight W of the elevator car 3 and its cargo can be calcu lated by means of a control unit CU.Thus, the system con sists of passive RFID for data communication and a power supply.

Figures 5 and 6 illustrate features that have al- ready been disclosed above in this document.

Figure 7 discloses a printed strain gauge 23 com prising a substrate 27 on which strain gauge elements 28a, 28b are printed together with possible wirings 29 and col lector parts 30 or data communication units.

In Figure 8 there is also shown a printed RFID tag 24 on the substrate 27. Further, it is also possible that the components of the strain gauge 23 are 3D printed di rectly on a surface of a load-bearing component of an ele vator. The strain gauge 23 is mounted or directly printed in areas that exhibit strain in compression or tension. The drawings and the related description are only intended to illustrate the idea of the invention. In its details, the invention may vary within the scope of the claims.