Lift installations comprise a lift cage, which moves in a vertical lift shaft of a building, for the transport of persons or articles. Lift installations are usually electrically operated. In the case of failure of the power supply of the lift installation, for example if the public power grid breaks down or in the event of an earthquake, it can happen that the lift cage becomes stuck in the lift shaft. Persons trapped in the lift cage have to be evacuated in such cases. For that purpose, it is necessary to know the position of the lift cage in the lift shaft. In practice, the rescuer who is responsible goes to the building. In order to locate the lift cage, shaft doors have to be opened so as to be able to check where the lift cage is. This can be very involved and time-consuming particularly in the case of higher buildings with a large number of storeys, since for this method of locating it is necessary for all shaft doors as far as the stuck lift cage to be opened. A further disadvantage of this method of locating is that the rescuer is exposed to potentially risky situations each time the shaft doors are opened.

It is accordingly the object of the present invention to avoid the disadvantages of the known method of locating and, in particular, to create a system for and a method of simple and certain locating of a lift cage, which is stuck in a lift shaft of a multi-floor building, with regard to evacuation of persons from this lift cage.

According to the invention this task is fulfilled by a system with the features of claim 1 . The system comprises identification means which are arranged at the lift cage. In addition, the system comprises receiving or reading apparatus with which the rescuer can use a staircase and which is connect ible with the identification means over a distance without contact-making (for example wirelessly). Identification means and receiving or reading apparatus can in that case communicate with one another in such a way that as soon as - when using the staircase with the receiving or reading apparatus - the receiving or reading apparatus and the identification means associated with the lift cage come into the range in which communication between receiving or reading apparatus and identification means is possible, a positioning or locating signal for determining the position of the lift cage can be generated by the receiving or reading apparatus. The receiving or reading apparatus can be designed in such a way that it can issue an appropriate report outside the range with respect to the identification means. This report can be, for example, a "no connection" display on a display of the receiving or reading apparatus.

In the case of use of identification means constructed as a transmitter and therefore able to transmit a signal, then if the receiving or reading apparatus comes into the transmission range of the identification means the signal is received by the receiving or reading apparatus and processed in the receiving or reading apparatus by means of a processor and the positioning or locating signal is generated. The system helps make possible in advantageous and simple mode and manner, thanks to the rapid finding of the stuck lift cage, fast evacuation of persons present in the lift cage. Already existing lift installations could be retrofitted with the system according to the invention in simple manner.

In a first form of embodiment the identification means comprise at least one RFID transponder. The RFID transponder can, for example, be arranged on the cage roof, a cage side wall or the cage floor, wherein the RFID transponder in that case is preferably to be provided in the region of a side, which faces the staircase, of the cage roof, cage side wall or cage floor. The receiving or reading apparatus can be an RFID reader. A system based on RFID can be installed and operated economically. A further advantage consists in the fact that a system, which is based on RFID technology, for locating lift cages which are stuck is operable securely and reliably.

The lift shaft and the adjacent staircase can be separated from one another by masonry or by one or more concrete walls. Consequently, with advantage efficient identification means, for example active transponders with a sufficiently large transmission power, are used depending on the respective design of the cage shaft and the distance of the staircase from the lift shaft. Transponders can comprise a microchip and antenna, for example in the form of a coil, wherein the two principal components (microchip, antenna) can be accommodated in a housing. Active or optionally also semi-active RFID transponders as identification means can ensure a sufficiently large range between receiving or reading apparatus and identification means. For regions in which the public power grid breaks down from time to time and thus the power supply of the lift installation can fail, it can be particularly advantageous if battery-operated active or semi-active RFID transponders are used. However, the active or semi-active RFID transponders can also be operated by way of another emergency supply.

Passive RFID transponders do not need an individual power supply. The energy, which is needed for communication and for processing internal processes, for the passive transponder comes from the radio signals of the RFID reader. On activation of the passive RFID transponder this transmits its signals back to the RFID reader. By contrast to passive RFID transponders, active RFID transponders have an individual energy supply and can transmit their stored data. The energy supply can be provided by, for example, an included battery or the active RFID transponder can be connected with an external power source. By contrast to active RFID transponders, semi-active RFID transponders do not have an individual transmitter, but semi-active RFID transponders only modulate their backscatter coefficients. In the case of semi-active RFID transponders a battery or possibly another power source takes over merely the power the supply of the microchip. The RFID transponder can be designed in such a way that it is activated only when the lift cage is stuck. For specific purposes of use, for example for wooden structures or other buildings in which the range is not limited by solid obstacles such as thick concrete walls and if the staircase directly adjoins the lift shaft, it would even be conceivable for the identification means to comprise at least one passive RFID transponder and, in particular, a passive RFID tag. RFID tags are readily available and particularly favourable in cost.

A further aspect of the invention relates to a method of locating a lift cage, which is stuck in the lift shaft of a multi-floor building, for evacuation of passengers from the lift cage. The building has a staircase close to the lift shaft. The method of locating comprises the following method steps: in the case of the lift cage becoming stuck in the lift shaft when there is a power failure or possibly in other cases a rescuer equipped with receiving or reading apparatus uses the staircase. This receiving or reading apparatus can in that case generate a positioning or locating signal which indicates that the receiving or reading apparatus is in the region of the range of the identification means of the lift cage or that the identification means of the lift cage is in the region of the range of the receiv ing or reading apparatus. As soon as the rescuer when using the staircase comes into the range in which communication between receiving or reading apparatus and identification means is possible then the position of the lift cage is determined by way of the positioning or locating signal generated by way of the receiving or reading apparatus. The mentioned determination of the position of the lift cage also comprises locating the stuck lift cage by association with a specific storey or - insofar as the lift cage is stuck between two storeys - by association with two storeys or an intermediate position between the two storeys. Exact knowledge of the cage position is thus obviously not absolutely necessary, since with respect to evacuation it is basically sufficient if the rescuer knows at which storey or between which adjacent storeys the stuck lift cage is located. The described method can, however, if required also be used for more precise determination of the cage position. The method can comprise, as a further method step, warning the rescuer when the lift cage is stuck as a consequence of, for example, a power failure and the warned rescuer goes to the building and climbs the staircase.

The method can be carried out particularly simply if a portable apparatus, particularly hand apparatus, is used as receiving or reading apparatus.

In addition, it can be advantageous if, when the receiving or reading apparatus and the identification means are disposed in range with respect to one another, an acoustic, visual and/or tactile signal is generated by the receiving or reading apparatus. For example, on detection of the identification means of the lift cage the receiving or reading apparatus can issue a beep, the loudness, tonal height and/or beep frequency of which changes or change in dependence on the distance of the receiving or reading apparatus from the identification means. If, for locating a stuck lift cage, the person climbs the staircase then when, for example, the range between receiving or reading apparatus and identification means is reached for the first time the receiving or reading apparatus generates an acoustic signal with slow beeping. When the person with the receiving or reading apparatus further approaches the lift cage a more rapid beeping is heard. At the same height, the receiving or reading apparatus generates a maximum beep frequency. If the person then continues to climb the staircase the beeping is again slower, whereby the person with the receiving or reading apparatus recognises that they are again going away from the lift cage. In this way the lift cage stuck in the lift shaft can be located in simple manner and also intuitively for comparatively less proficient persons.

Identification means and receiving or reading apparatus can be designed in such a way that the range is between 2 and 5 metres, preferably approximately 3 metres.

Individual features and advantages of the invention are evident from the following description of an embodiment and from the drawing. The figure shows a substantially simplified illustration of a building with a lift installation and the system according to the invention for locating the lift cage.

The figure shows a building, which is denoted by 1 , or at least a part detail of the building with a lift installation, which comprises a lift cage 3 vertically movable in a lift shaft 2. The lift cage 3 of the lift installation is, by way of example, fastened or suspended at a plurality of support cables (not illustrated here) and is movable upwardly and downwardly by way of drive means (for example, by way of a drive-pulley drive) known to the expert as such. Instead of support cables, other support means such as individual or multiple support belts of different materials and compositions such as plastics, metals or other materials can also come into consideration. However, the locating method described in more detail in the following is obviously also suitable for other installation types such as, for example, hydraulically operable lifts or rack lifts. Apart from the lift shaft, the multi-floor building 1 has a staircase 4.

An RFID transponder 7 is arranged in the region of the cage roof of the lift cage 3 at the side facing the staircase 4. The RFID transponder 7 serves as identification means for recognition of the lift cage 3. A rescuer, who is denoted by 5 and who uses the staircase 4, holds an RFID reader 6 as receiving or reading apparatus in his or her hand. This receiving or reading apparatus can be hand apparatus, which was created specifically for the purpose explained in detail in the following. However, it is also conceivable to use, for example, a smartphone RFID reader as receiving or reading apparatus, onto which appropriate software were or an appropriate app was loaded. RFID transponder 7 and RFID reader 6 can communicate with one another.

The present multi-floor building 1 illustrated by way of example has a ground floor denoted by "Ground Floor" and thereabove a storey denoted by " 1 st Floor", as well as further storeys, wherein in the present embodiment the uppermost storey is finally denoted by "6th Floor". Instead of the seven-storey building illustrated here obviously also a greater or lesser number of storeys would be conceivable. In the case of unstable public power grids or in the event of natural catastrophes (such as, for example, in the event of an earthquake) it can happen that the lift cage 3 becomes stuck in the lift shaft due to power failure. A situation of that kind is illustrated by way of example in the figure. In the figure, the stuck lift cage 3 is between the second and third storeys ("2nd Floor", "3rd Floor"). By means of a speaker symbol and arcs it is, in addition, symbolically indicated in the figure that depending on the respective design of the system comprising identification means 7 and receiving or reading apparatus 6 the stated components of the system can be constructed as transmitters. For example, in the case of use of identification means 7 (for example, active RFID tags), which are constructed as transmitters and therefore can transmit a signal, then when the receiving or reading apparatus 6 comes into the transmission range of the identification means 7 the signal is received by the receiving or reading apparatus 6 and processed in the receiving or reading apparatus 6 by means of a processor (not illustrated here) and the positioning or locating signal is generated. For example, in the case of use of passive identification means 7 (for example, passive RFID tags) the receiving or reading apparatus 6 would also have to function as a transmitter, When the lift cage is stuck as a consequence of a power failure the rescuer 5 can be warned, for example, by an emergency call system. Coming into consideration as rescuer 4 are, for example, members of the police, members of the fire brigade, a caretaker in the building concerned or also service personnel of a lift company. The rescuer 5 who has been warned or otherwise made aware of the lift cage being stuck then goes to the building 1. If the RFID transponder 7 and the RFID reader 6 can, for example, communicate with one another only at a distance of 3 metres, i.e. the range is 3 metres, the RFID reader 6 at the ground floor will still not deliver a positioning or locating signal. The rescuer 5 will thereupon climb the staircase. As soon as the RFID reader 6 comes into the range of the RFID transponder, the RFID reader 6 generates a positioning or locating signal. The positioning or locating signal can be or comprise, for example, an acoustic signal such as a beep. The rescuer 5 now knows that he or she is in the vicinity of the lift cage 3. By way of example, in the present case this is so for the position of the person 5 shown in the figure. The rescuer thus recognises, thanks to the RFID reader 6, that the lift cage 3 is between the second and third storeys. The system, which is shown here, comprising identification means 7 and receiving or reading apparatus 6 for locating a lift cage stuck in a lift shaft 2 of a multi-floor building 1 , thus ensures rapid and efficient evacuation of persons from the stuck lift cage 3.

When the rescuer for locating a stuck lift cage initially enters the building 1 and climbs the staircase starting from the ground floor then by way of example when the range between RFID reader 6 and RFID transponder 7 is reached for the first time the RFID reader 6 will generate an acoustic signal with a slow beeping. An RFID reader 6 with a beep as acoustic positioning or locating signal will on detection of the identification means of the lift cage 3 deliver a beep with a loudness, tone level and/or beep frequency which changes or charge in dependence on the distance of the RFID reader 6 from the RFID transponder 7. The RFID reader 6 is advantageously designed in such a way that - if the rescuer 5 continues to climb - the beep or other positioning or locating signal of the RFID reader increases in strength. When the person with the RFID reader 6 further approaches the lift cage, a more rapid beeping is heard. At the same height the RFID reader 6 generates a maximum beep frequency. If the rescuer then continues to climb the staircase 4 the beeping is slower again, whereby the rescuer with the RFID reader 6 recognises that he or she is going away from the lift cage.

In this way the position of the stuck lift cage 3 can be determined precisely. After determination of the cage position the rescuer 5 goes to the third or otherwise even the fourth storey if the trapped person has to be rescued by way of the roof of the lift cage 3. The rescuer 5 carries portable apparatus in the form of an RFID reader 6. Such an RFID reader 6 can be carried by the person 5 even before being warned. However, it is also conceivable for it to be available in an access region of the building 1 in an area preferably accessible only to a specific circle of persons, for example a closable storage box for at least one reader.

Tests have shown that reliable locating can be achieved particularly preferably with battery- operated active or semi-active RFID tags as identification means 7. The battery ensures that even in the case of power failure a sufficiently strong RFID signal is emitted by the RFID tag 7 on the lift cage 3 for a sufficient length of time, which signal is receivable by the RFID reader 6 and on reception by the RFID reader 6 can be converted into a positioning or locating signal.