I Measuring device for a lift installation as well as a lift installation with such a measuring device 1 FiLed ofQthe invention The invention relates to a measuring device for a lift installation with at least one lift cage aa c spending ft installation, 2. Background of thne Lift cages in a lift instalation are typicaly each equipped with an own drive and an own braking system. The electronic control of the entire lift installation is frequently designed so that collisions of the individual lift cages with stationary obstacles connected with a travel path, such as a travel path end or an adjacent lift cage, should not occur, The travel path is usually defined by a shaft and a travel path end by a shaft end. The travel path can instead also be designed as a framework or box construction or something else, By travel path there is understood here not only the space directly occupied by a lift rage, but also the space adjoining threat, which is, for example, bounded by the shaft space. In the case of, in particular, an emergency stop, or also a normal stop at a storey, of a cage it cannot be guaranteed in all circumstances that a further lift cage located above or below on the same travel path can still stop in good time in order to avoid a colision, This could be avoided by predetermining, through the control, sufficient spacings between the individual lift cages and also appropriately adapted vertical speeds. However, through such a predetermination it is not possible to fuly utilise the transport capacity of a lift installation, which has an influence on the costiuse efficiency, A lift installation is now known from European Patent Specification EP 769 469 B1 which comprises means for opening the safety circuit of a lift cage if an undesired approach to another lift cage occurs. According to the said patent specification safety modules are present at each lift cage, which modules evaluate the cage positions and speeds so as, in a given case, to be able to trigger braking processes even at other lift cages. The individual safety modules have to constantly recognise and evaluate the cage positions and speeds of the other participating lift cages in order to be able to correctly rac in an emergency situation, A special decision module, which in the case of emergency is responsible for determination of the stopping commands, is needed for that purpose, 2 A similarly expensive solution is known from international Patent Application WO 20041043841 Al, According to this patent application, infrared, laser or ultrasonic sensors can be arranged at each lift cage and measure the spacing from the adjacent lift cages located above and below and the lift cage, Moreover, use of a travel path or shaft information system is additionally proposed so that, for example, measuring strips arranged in the region of the travel path can be scanned by sensors, in the form of light barriers, at the lift cages. This electro-opticai approach also makes it possible to control the spacing of the lift cages and in a given case also the spacing from a travel path end, such as an upper or lower shaft end, and if necessary to intervene in the control so as to prevent a collision. The solution described in International Patent Application WO 2004/043841 Al is, above a2l, expensive because it obliges a communication between different opto-electronic components of the lift cages so as to enable statements about the instantaneous spacing and the instantaneous speeds of the lift cages, Moreover, the described solutions are cornplicated to initialise when placing in operation since all systems have to be tuned to one another. The complexity of the systems makes these solutions possibly also susceptible to fa ut, Taking into account the known arrangements it is desirable to provide a measuring device arrangement which allows to simplify the operation of a lift installation, 3 Summary of the Invention The present invention provides a measuring device for lift installations which is equally suitable for prevention of a collision between, two lift cages which relatively approach one another along a common travel path as well as also for prevention of collisions between a lift cage and a travel path end, Equivalent variants of the measuring device according to the invention for a lift installation are described in the following. in a first variant according to the invention the measuring device for a lift installation having at least one lift cage which is movable along a travel path of the lift installation, has at least one transmitter and receiver pair that can interact with one another during travel of the lift 3 cage. For each lift cage, the receiver is arranged at the lift cage and the transmitter at the travel path or the transmitter is arranged at ihe lift cage and the receiver at the travel path. The transmitter is arranged to deliver a beam at a first fixed angle with respect to the travel direction. The first angle is so predetermined that the beam is incident on the receiver on approach of the lift cage to an obstacle stationary with respect to the travel path. With the first variant, the measuring device can also be of redundant design. For that purpose, a second transmitter and receiver pair is provided and deployed in an arrangement that is converse to the arrangement of the transmitter and receiver of the first pair. For example, if the first transmitter is arranged at the travel path and the first receiver is arranged on the first lift cage, the second transmitter will be arranged on the lift cage and the second receiver will be arranged at the travel path, In addition, a redundant design of the measuring device can be similarly achieved in that two transmitters are arranged on the travel path and two receivers on the lift cage. In a second variant according to the invention, the measuring device for a lift installation having at least one lift cage movable along a travel path of the lift instalation, has at least one transmitter and receiver pair, wherein both the receiver and the transmitter are arranged at the iift cage or at the travel path. The transmitter delivers a beam at a first angle with respect to the travel direction, The first angle is so predetemniined that the beam is incident on the receiver on approach of the lift cage to an adjacent lft cage or an obstacle stationary with respect to the travel path, According to the second variant, the measuring device requires at least one reflector which arrangedilocated such as to reflect to the receiver a beam delivered by the transmitter theppoc o h lif bya ubl~ke on approach of the lift cage to an adjacent lift cage or the stationery object. if the transmitter and the receiver are arranged at the travel path then the reflector is mounted at the lift cage. Conversely, if the reflector is mounted at the travel path then the transmitter and receiver are arranged at the lift cage. in this second variant as well, the measuring device can be of redundant design. For that purpose, a second transmitter and receiver pair is arranged at the lift cage and the travel path, as the case may be, in addition, a redundant design of the measuring device is similarly achieved in that two transmitters and two receivers are arranged at the lift cage or at the travel path. In a third variant according to the invention, the measuring device for a lift installation 4 having two lift cages movable along a travel path of the lift installation, has at least one transmitter and receiver pair wherein the receiver is arranged at a first one of the lift cages and the transmitter is arranged at a second one of the lift cages. The transmitter delivers a beam at a first angle with respect to the travel direction, The first angle is so predetermined that the beam is incident on the receiver on approach of the lift cages towards one another. The measuring device of the third variant can also be of redundant desirign An additional transmitter and receiver pair will then be provided and so arranged at the lift cages that either two transmitters are arranged on the first lift cage and two transmitters on a second lift cage or a respective transmitter and receiver are arranged on each of the first lift cage and a second lift cage, With knowledge of the above variants it is open to the expert to also realise a combination of all variants in a lift installation, in addition, the measuring device according to the invention and in accordance with the three variants can be equipped with one or more additional reflectors which are arranged at a lift cage and/or at the travel path and which reflect to a receiver a beam incident thereon from the transmitter, In all three variants, the sensor arrangement is such that tie transmitter delivers a beam which is detectable by an associated receiver, This transmitter and receiver pair and, in a given case, one or more associated reflectors are so arranged in the region of the travel path and the lift cages that on movement of one or more lift cages the beam of the transmitter generates a moving measuring point on the receiver and/or if required on a reflector, The receiver and/or the reflector in that case defines or define a reaction region, in which a suitable reaction can be triggered, in terns of time or location. This reaction region can, for example, be used for the purpose of providing compensation for system reaction times or building tolerances. The receiver has, for detection of the beam, a sensor region with one or more sensitive sensor regions. If the sensor region is subdivided into several sections, these can preferably be evaluated separately. For that purpose the receiver in preferred manner comprises an evaluating system in order to be able to trigger ari appropriate reaction in dependence on the section on which the beam is incident.
Advantageously, this sensor region is arranged perpendicularly to the lift cage or to the travel path, The settling of dust particles on the sensor region can thereby be minimised. In order to protect the sensor region even better against settling of dust particles, this can be positioned to be overhanging with respect to a vertical direction, i.e. with the sensitive sensor side inclined downwardly in an angular range of 0 to 90*. This variant is preferably usable in conjunction with a reflector, The beam produced by the transmitter can be based on different physical principles. In that case the beam comprises electromagnetic, electrical or magnetic waves, sound waves or light waves. The sensor region of the receiver is thereupon tuned to the beam depending on the respectively selected variant of embodiment to be received. In preferred manner, transmitter and receiver are selected to transmit or receive infrared, laser or ultrasonic beams. The angle between the beam and the travel direction is variably settable in time depending on single or multiple parameters, In that case a position, a speed or an acceleration of a lift cage, a spacing, a relative speed and/or a relative acceleration and/or an operational state of the lift installation is or are selectable as parameter or parameters, An additional variant of use of the measuring device according to the invention is offered particularly in a case of a receiver with a sensor region subdivided into several sections. Since each section can be separately evaluated, the sensor can, for as long as this lies in the region of the moving measuring point, be evaluated with respect to the position of a lift cage. In the case of appropriate length of the sensor region and/or positioning of the transmitter, receiver and/or reflectors and/or setting of the angle the measuring device can also be used as an absolute position detection device. An advantage of the invention results from the simple arrangement of ccmmercially available comoonents in order to realise a measuring device which realises a distance control or a combined distance and speed control and/or determines a position of a lift cage relative to the travel path. A further advantage resides in the automatic determination of the spacing by the receiver and the triggering of an autonomous reaction in the event of undesired approach of a lift cage to a travel path end or to an adjacent lift cage. Moreover, the receiver in co-operation with a local computing unit is capable, with low computing outlay, of triggering a collision-preventing reaction on the basis of speed data. Moreover, the redundant design of the measuring device offers additional safety and enables an autonomous and rapid collision-preventing reaction of a lift cage. The invention is described in the following by way of exemplifying embodiments and with reference to the drawings. 4. Brief Description of the Drawinns Fig, 1A shows a side view of a first lift installation according to the invention at a first poirt in time; Fig, 1B shows a side view of The iinstaltion according to Fig, 1A at a later point in ti me; Fig. 2 shows a side view of a part of a second lift installation according to the invention; and Fig. 3 shows a side view of a part of a third lift installation according to the invention. 5.- esio r~ rred enbodwments A lift installation typically has at least one lift cage which is suspended by way of a traction means. in order to provide compensation for the cage weight there is preferably provided a counterweight of the lift Ialilation, which is similarly connected with the traction means. For drive of the lift cage the lift installation is equipped with a drive comprising a drive pulley, a motor and optionally a stopping brake. In that case the drive puiley and the traction means are in operative contact, The drive pulley and the motor are usually connected together by way of a shaft and/or a transmission so that the motor moves the lift cage via rive pulley and traction means. The space which the lift cage travels through is predetermined by a travel path, The travel path in that case comprises the space directly required by the lIft cage, as wail as also the space adjoining thereat, The space predetermined by the travel path is usuaiiy bounded by a lift shaft. To that extent the terms travel path and lift shaft can be understood to be synonymous, The lift shaft is laterally defined by four shalt walls as wel as by a shaft Sa ceiling and shaft base, The shaft ends denote a region of the shaft ceiling or the shaft base as well as embrace the adjoining upper or lower part of the shaft walls. The measuring device has at least one transmitter and an associated receiver. The transmitter transmits a beam receivable by the receiver,. The receiver can trigger a reaction on the basis of a received beam directly or in conjunction with a connected control unit, Reflectors are optionally also a component of a measuring device. In that case the reflectors reflect the beam: which is transmitted by a transmitter, directly or via one or more reflectors to a receiver, In the illustrated examples the transmitter is preferably designed as a light source which delivers a light beam in the visible or invisible wavelength range. The receiver correspondingly possesses a light-sensitive sensor region enabling reception of the light beam, IFI (43L 7 A first form of embodiment of the invention is described in connection with the two snapshots in Figures 1A and 1B. A simple lift installation 10 with an upper lift cage Al and a lower lift cage A2, which are both movable vertically along a travel direction z substantially independently on a common travel path 11, for example a lift shaft 11, of the lift installation 10, is shown. For this purpose the lift cages A1, A2 can be provided with a respective drive and stopping brake per lift cage Al, A2 or, for example, can be individually coupled to a central drive system so as to enable individual movement along the travel path 11. Beyond that there are also other approaches to make possible individual movement of the lift cages of a lift installation. The lift cages are, in the case of appropriate orientation of the travel path, also movable horizontally or in another direction. A measuring device can be provided which, for example, comprises a first electro-optical measuring device 20 with a first transmitter, for example a light source 21, which is arranged in a lower region of the upper lift cage Al, as schematically indicated in Figures 1A and 1B. Light-emitting diodes, which issue focused light, are particularly suitable as light sources. Even more suitable are laser diodes or solid-body lasers. In addition, the measuring device 20 comprises a first receiver 22, which comprises a light sensitive first sensor region 22 in an upper region of the lower lift cage A2. Photodiodes, phototransistors or other light-sensitive elements can be used as sensor region 22. The first light source 21 is so designed and arranged that it delivers a focused first beam in the form of a light beam Li at a first angle W1 with respect to the travel direction z. In the illustrated example the light beam L1 is oriented downwardly. A snapshot is shown in Fig. 1A (spacing between the cages is S1) where the upper lift cage Al moves downwardly at a speed v1 and the other lift cage A2 is stationary (v2 = 0). At the illustrated instant the light beam LI impinges wherever above the lower lift cage A2 against a wall of the lift shaft 11. If now the relative spacing of the two lift cages Al and A2 reduces to a minimum spacing S2, as shown in Fig. 1 B, then the light beam L1 is incident for the first time on the sensor region 22 of the receiver. According to the invention the first angle W1 is so predetermined or set that in the event of IP1743E 8 approach of the upper and lower lift cages Al, A2 the first light beam Li is incident on the first sensor region 22 as soon as the minimum spacing S2 is attained. At this instant of incidence the light beam Li is thus detectable by the first receiver 22, 24 and this receiver 22, 24 triggers a reaction R1 which, for example, is passed on by way of a line or connection 23 to a control or the like. The present invention now permits different forms of realisation or constructions of the measuring device. In the simplest form of a realisation a reaction can be triggered directly on the first occasion of incidence of the light beam Li on the sensor region 22. In this case it is sufficient if the sensor region 22 has a size - in a sense of area extent - which allows it to ensure that notwithstanding the fluctuations in the lift installation 10 a reliable detection of the light beam LI by the receiver 22, 24 is thus possible. A further form of realisation of the invention is indicated in Fig. 2. In this figure a snapshot shows shortly after the light beam Li was detected for the first time by a light-sensitive section 22.1 of the sensor region 22. The sections can preferably be evaluated separately, i.e. they each have respective individual electrical connections. For preference, in the various forms of embodiment an appropriate evaluating system 24 (or 24 and 28 in the case of Fig. 3) is provided so as to be able to trigger an appropriate reaction (R1, R2, R3, R4) in dependence on which of the sections 22.1 - 22.n is hit by the first light beam L1. If now the same spacings as in Figures 1A and 1B are assumed, then at the illustrated instant the spacing would be less than S2. Since the upper lift cage Al further moves at the speed v1 towards the lower lift cage A2 the 'light spot' produced by the light beam LI displaces to the left. The measuring device can now be designed, programmed or adjusted so that on the first incidence on the section 22.1 of the sensor region 22 an advance warning as reaction is given or the lift installation 10, or the lift cage Al and/or A2, is transferred to an advance warning mode. If now the light spot goes beyond a previously fixed further section 22.4 of the sensor region 22 then a final reaction can be triggered (for example an emergency stop by triggering the braking 1II- f43E 9 device or the safety brake of the upper and/or lower lift cage Al 1 , A2. This two-stage approach offers additional safety and thereby helps to avoid erroneous triggerings. A further form of realisation of the invention is now explained by reference to Fig. 2. As indicated by an arrow below the sensor region 22, the light point travels at a speed vi * to the left when the relative spacing between the lift cages Al, A2 reduces at a speed vi. This speed v1* allows a computerised determination of the speed vi with use of simple trigonometric formulae. If the angle Wi is, for example, 45 degrees, then v1 = v1*, since tan 45 = 1. If the angle W1 is greater than 45 degrees, then v1 * is also greater than vi. In the case of the smaller angles W1, v1* is less than vi, i.e. there is obtained a form of speed step down or slowing down. The size of the sensor region 22 can be reduced by a such a slowing down, which can possibly be of advantage, since the appropriate sensors are expensive. A further variant is shown in Fig. 3. This variant is currently preferred, since it offers the greatest reliability. Use is made, as shown, of two electro-optical measuring devices. The first measuring device is designed analogously to the system shown in the preceding figures. The second measuring device can be of the same construction, but is seated quasi in mirror image in the upper region of the lower lift cage A2. The corresponding second sensor region 26 is seated in the lower region of the upper lift cage Al. In the illustrated example both angles are the same, i.e. W1 = W2. However, the angles can also be preset or adjusted differently. In the case of identical realisation of the electro optical measuring device and if Wi = W2, the two electro-optical measuring devices provide signals at the same time or trigger reactions R3, R4 at the same time. It is schematically indicated in the figures that the receivers trigger respective reactions. The form of reactions differs according to the respective form of embodiment, programming or adjustment of the devices. It is indicated in the figures that the receivers are in a position of delivering signals or data by way of lines or other connections 23 or 27. These signals or data are then either processed before reactions are triggered or they directly trigger the reactions in that, for example, they open a switch which is part of a safety circuit. There are numerous possibilities of managing the triggering of the reactions. The IP1 743E 10 respective realisation depends on different details of the respective lift installation 10. If, for example, the lift installation 10 has an individual safety circuit per lift cage Al, A2, then the safety circuit of the upper and/or lower lift cage Al, A2 can be interrupted by the receiver or receivers. A lift installation 10 preferably has an individual safety circuit per lift cage Al, A2 in which several safety elements such as, for example, safety contacts and safety switches are arranged in a series connection. The corresponding lift cage Al or A2 can be moved only when the safety circuit and thus all safety contacts integrated therein are closed. The safety circuit is connected with the drive or the brake unit of the lift installation 10 in order to interrupt travel operation of the corresponding lift cage Al or A2 if such a reaction is desired. However, the invention can also be used in lift installations which are equipped with a safety bus system instead of the mentioned safety circuit. Alternatively or additionally to opening the safety circuit the brakes of the respective lift cages A1, A2 can also be triggered. Alternatively or additional some safety brakes of the respective lift cages A1, A2 can be triggered. Thus, one or several of the following reactions can be triggered by the receivers 22, 24 or 26, 28 depending on the respective form of embodiment: - opening a safety circuit of at least one lift cage Al, A2, - signal to a lift cage - triggering a brake device of at least one lift cage Al, A2, - triggering a safety brake of at least one lift cage Al, A2, - transferring at least one lift cage Al, A2 to an advance warning state, - adaptation of the vertical speed v1, v2 of at least one lift cage Al, A2. Thus, a distance control or a combined distance and speed control can be realised by the invention. The angles W1, W2 can be set in a range of 0 to 904 with respect to the vertical direction IP1743E 11 z. The angles W1, W2 preferably lie in a range between 0 and 60 degrees and, particularly preferably, between 10 and 50 degrees. Advantageously the angle W1, W2 is set to be variable in terms of time in dependence on single or multiple parameters such as the position, speed or acceleration of a lift cage Al, A2, the spacing, relative speed or relative acceleration of the lift cage Al, A2 with respect to a reference point, or the operational state of the lift installation 10. By virtue of the setting of the angle W1, W2 it is possible, for example, to set the angle W1, W2 to be smaller in the case of a higher speed of the cage Al, A2 so that the light beam L1, L2 is incident on the receiver 22, 24 at an earlier point in time and thus this can trigger a reaction R1, R2, R3, R4 at an earlier point of time. With a lower speed, the necessity of an early reaction R1, R2, R3, R4 correspondingly reduces and thus a greater angle W1, W2 can be set. The correlation between acceleration and angle behaves in analogous manner. The operational state of a lift installation 10 such as, for example, in the inspection or maintenance state often presets a reduced maximum speed. Thus, in the case of an inspection travel of the lift cage Al, A2 the angle W1, W2 of the light beam L1, L2 can be increased already after transfer of the lift cage Al, A2 to an inspection state, since the lift cage Al, A2 can be moved only at a reduced speed. The position of the lift cage Al, A2 serves, for example, for the purpose of determining the instant of a variable setting of the angle W1, W2. A critical spacing between the lift cages Al, A2 or between a lift cage Al, A2 and the shaft end is correspondingly defined. If this value is fallen below, the variable setting of the angle W1, W2 begins. If several lift cages travel in the same shaft 11 then a corresponding measuring device can also be provided between these lift cages. A second form of embodiment of the invention relates to a lift installation with a lift cage which is movable in travel direction along a travel path or lift shaft. For this purpose the lift cage Al in correspondence with the first form of embodiment is to be equipped with, for example, a drive and a stopping brake. A measuring device is provided which comprises, for example, a first electro-optical measuring device with a first transmitter, for example a lil (46t 12 light source, which is arranged in a lower region of the upper lift cage. In addition, the measuring device comprises a first receiver, which comprises a light sensitive first sensor region at the lower travel path end. The first light source is so designed and arranged that it delivers a focused first light beam at a first angle with respect to the travel direction. In the described example the light beam is directed downwardly. In a variant the positions of the light source and the receiver can also be exchanged so that the receiver is positioned in the lower region of the lift cage and the light source in the region of the lower shaft end. Moreover, corresponding sensor regions can also be provided at the upper shaft end of the lift cage so as to prevent a risky approach of the lift cage to the upper shaft end. A third form of embodiment of the invention relates to a lift installation with a lift cage which is movable in travel direction along a travel path or lift shaft. For this purpose the lift cage in correspondence with the first form of the embodiment is equipped with, for example, a drive and a stopping brake. A measuring device is provided which comprises, for example, a first electro-optical measuring device with a first transmitter, for example a light source, which is arranged in the region of the upper shaft end. Moreover, the measuring device comprises a first receiver, which comprises a light sensitive first sensor region similarly in the region of the upper shaft end at a spacing from the light source. The first light source is so designed and arranged that it delivers a focused first light beam at a first angle with respect to the travel direction. In addition, the measuring device comprises a reflector which is arranged in the upper region of the lift cage. The position of the reflector is determined in such a manner that on approach of the lift cage to the upper shaft end the light beam is incident on the reflector and is reflected by this to the receiver of the measuring device. The dimensioning of the reflector and of the light-sensitive sensor region of the receiver are preferably matched to one another so that in the course of approach of the lift cage to the upper shaft end the light beam runs through the entire sensor region. In the described example the light beam between the light source and the reflector is oriented downwardly and, after the reflection, upwardly to the receiver.
IP 143L 13 In a variant the light source and the receiver are arranged in the upper region of the lift cage and the reflector in the region of the upper shaft end. Moreover, corresponding measuring devices can also be provided at the lower shaft end of the lift shaft so as to prevent a risky approach of the lift cage to the lower shaft end. The principle of operation of the measuring device of the second and third form of embodiment is the same as in connection with the other forms of embodiment. To that extent, the afore-described variants can be combined with one another almost as desired.