Prior art In recent elevator systems, safety aspects for the passengers and the maintenance staff have gained an increasing attention.

For example, a safety problem arises if the elevator cabin in case of emergency or breakdown stops between two floors such that a gap is formed between the elevator cabin and the hoistway. In order to protect persons from falling into the hoistway under such circumstances, so-called guard members have been proposed which a installed on the bottom of the elevator cabin and close the above-mentioned gap.

For example, US 6,095, 288 discloses a pit-less elevator with an elevator cabin having a toe guard generally being in an open position but being retracted when the elevator cabin is in its lowest position.

With such solutions, however, the guard member has to be retracted and extended every time the elevator enters the its lowest position in the hoistway leading to noise and wear during operation. In order to overcome this problem, DE 101 15 990 Cl discloses an elevator system in-which the guard member is generally in its retracted position and is extended only in case of emergency, breakdown or the like. However, DE 101 15 990 Cl provides no solution how to return the guard member from its extended to its retracted position.

Summary of the invention It is an object of the present invention to provide an elevator system having a simple construction and, in particular, allowing a safe and durable operation of the guard member.

This problem is solved by an elevator system according to claim 1. Preferred embodiments of the invention are defined in the dependent claims.

In particular, the elevator system according to the invention comprises a mechanism for automatically returning the guard member to the retracted position, the mechanism being actuatable by means of a movement of the elevator cabin. In this way, no separate drive unit is required for returning the guard member from the extended into the retracted position. Instead, the guard member can be returned using a simple mechanism which is actuated by a conventional movement of the elevator cabin.

In combination with the retaining means and the control means, the elevator system allows a smooth operation of the elevator cabin and avoids wear of the guard member while providing a simple and reliable reset of the guard member from the extended into the retracted position.

According to a preferred embodiment of the present invention, the mechanism comprises a first operation part connected to the guard member and a second, stationary operation part, the first and second operation parts being engagable during the movement of the elevator cabin. With this construction, the mechanism can be realised with simple and commonly available components.

Further, in order to avoid constraints and noise during engagement of the mechanism by means of a movement of the elevator cabin, it is preferred that the first and second operation parts are adapted to permit relative movement between one another.

The elevator system according to the present invention is appropriate for hoistways with or without so-called pits.

However, in modern buildings the dimensions of pits are more and more limited such that the space below the elevator cabin reduces. In order to meet these requirements, the present invention proposes that the first and/or second operation parts are arranged outside a vertical projection at least of the bottom face of the elevator cabin. As a result, the mechanism of the present invention does not require additional space below the elevator cabin such that the inventive elevator system can be applied to hoistways with small pits or even without pits.

In this context, it is also preferred that the first operation part is partially located above a bottom face of the elevator cabin when the guard member is in its retracted position such that an interference of the mechanism with the pit of the hoistway is avoided.

In this context, it is even more preferred that the pivot joint is located on or above a bottom face of the elevator cabin allowing the most compact construction possible.

In order to provide a smooth and noiseless operation of the mechanism of the inventive elevator system, it is preferred that the first operation part comprises at least one lever having a free end, the free end having a roll. As a result, a relative movement between the first and second operation parts can be achieved by at least one roll avoiding wear and noise during friction of these parts.

According to a preferred embodiment of the present invention, the second operation part comprises at least one surface which is engageable with the first operation part and is curved and/or inclined with respect to the travelling direction of the elevator cabin. In this way, the second operation part allows to transform the movement of the elevator cabin into a return movement of the guard member without requiring active components such as drive units and the like.

With regard to an appropriate safety function of the inventive elevator system, it is preferred that the retaining means comprises at least one electromagnet the actuation of which is controllable by the control means. This construction allows that the guard member can be set from the retained into the extended position within a minimum time period while maintaining a simple construction. Further, the provision of a electromagnet supports the return movement of the guard member from the extended to the retracted position.

Further, according to a preferred embodiment of the invention, the retaining means comprises a detection means for detecting presence of the guard member in the rejected position. In this way, it can be guaranteed that a normal operation of the elevator system is maintained or initiated only if the guard member is in its retracted position so as to avoid accidents or collisions induced by the guard member.

In order to further assist the return movement of the guard member from the extended to the retracted position, it is preferred that the elevator system comprises at least one fixed elastic element located in the travelling path of the elevator cabin and contacting the guard member at least in the lowest position of the elevator cabin. Accordingly, it is one function of the at least one fixed elastic element to apply a pressing force on the guard member when the guard member is moved from its extended to its retracted position. As a result, the inventive mechanism needs to apply a smaller return force on the guard member leading to an even more simple and compact construction.

According to another embodiment of the present invention, the elevator system further comprises emergency sensors detecting an emergency state and connected to the control means. In particular, such emergency sensors can be provided in at least one access door to the hoistway and detect whether or not the access door is being unlocked. An unlocking signal can then be transferred to the control means which, in turn, causes the guard member to be released and to move from the retracted position to the extended position.

The movement of the guard member from the retracted, generally horizontal position to the extended, generally vertical position can for instance be achieved by gravity. Under such circumstances, in order to provide a smooth movement of the guard member and to avoid a noisy striking of the guard member, it is preferred that the elevator system comprises a damping element connecting the guard member with the elevator cabin. As a result, the movement of the guard member can be controlled such that a quick safety function is achieved while avoiding noise and wear.

With regard to a compact construction which allows simple installation and maintenance, it is preferred that the elevator system comprises a drive unit which is mounted in the hoistway below or beside the elevator cabin and/or the control means. As a result, the drive unit is easily accessible for the maintenance staff which also contributes to increased safety.

The safety properties of the inventive elevator system can be further increased by a control panel connected to the control means and mounted in an architrave and/or a wall of the hoistway. This control panel is preferably connected to the control means and allows a remote control of the elevator system from the outside of the hoistway. Further, this arrangement improves the fire safety of the elevator system.

Brief description of the figures Fig. 1 shows a schematic side view of an elevator system according to a preferred embodiment of the invention; Fig. 2 shows schematic, partial front views of the mechanism according to a preferred embodiment of the invention in the extended position (Fig. 2a) and in the retracted position (Fig. 2b); Fig. 3 shows schematic, partial side views of the mechanism according to a preferred embodiment of the invention in the extended position (Fig. 3a) and in the retracted position (Fig. 3b) ; Fig. 4 shows a schematic, partial side view of the interaction of operation parts according to a preferred embodiment of the invention; Fig. 5 shows a schematic, partial side view of the operation of the mechanism according to a preferred embodiment of the invention.

Detailed description of preferred embodiments Preferred embodiments of the present invention are described below with reference to the enclosed figures.

Fig. 1 shows a schematic side view of an elevator system 1 according to a preferred embodiment of the invention. The elevator system 1 comprises an elevator cabin 10 travelling up and down a hoistway 2 which has several access doors 4. The elevator cabin has a bottom part 14 on which a guard member 12 is mounted via a pivot joint 16.

Further details of the bottom part 14 and the guard member 12 are illustrated in Figs. 2 and 3 which show schematic, partial front and side views, respectively, of the Fig. 1 embodiment.

As can be seen in Figs. 2 and 3, the guard member 12 is movable between a retracted position (Fig. 2b, 3b) and an extended position (Fig. 2a, 3a). In the present embodiment, the retracted position of the guard member 12 is essentially parallel to the bottom part 14 of the elevator cabin 10.

However, the retracted position generally is such a position of the guard member 12 that it does not disturb the normal operation of the elevator cabin 10 in the hoistway 2. Likewise, the extended position of the guard member 12 in the present embodiment is essentially parallel to the travelling direction of the elevator cabin, even though any other position suitable for protecting persons from falling into the hoistway 2 is also possible.

Further, the elevator system 1 comprises at least one electromagnet 18 for releasably retaining the guard member 12 in the retracted position during normal operation of the elevator system. Of course, any other suitable means for releasably retaining the guard member in the retracted position can be used, even though means which are controllable by electric commands are preferred.

Even though not shown in the Figures, the retaining means 18 comprises a detection means, for example a switch or the like, for detecting presence of the guard member 12 in the retracted position.

Moreover, the elevator system 1 has a mechanism 30 for automatically returning the guard member to the retracted position. The details of the mechanism 30 are shown best in Figs. 2 to 4. In the preferred embodiment, the mechanism 30 comprises a first operation part 32 which is formed by an arrangement of jointed levers. At least one of these levers comprises an end portion 36 which is provided with a roll 38.

Further, the arrangement of levers which is best seen in Fig.

3a) connects the guard member 12 to the bottom part 14 of the elevator cabin.

As can be seen in Fig. 2, the arrangement of levers 32 including the roll 38 is arranged outside a vertical projection of the bottom face (the lower surface of the bottom part 14) of the elevator cabin. Additionally, in the retracted position of the guard member 12, the roll 38 and a part of the lever arrangement 32 are located above the bottom face of the elevator cabin (Fig.

2b).

In addition to the lever arrangement (the first operation part) 32, the mechanism 30 of the present invention comprises a second operation part 34, which is fixedly mounted in the hoistway 2.

The second operation part 34 of the present embodiment is illustrated in Fig. 4 and is formed by a rail which has a surface 34'which is inclined with respect to the travelling direction of the elevator cabin 10. As can also be seen in Fig.

4, the first and second operation parts 32,34 are arranged such that they are engageable with each other.

In addition to the components shown in the Figures, the elevator system according to the present invention comprises emergency sensors detecting an emergency state, for example emergency switches detecting whether or not at least one access door 4 to the hoistway is being unlocked. Moreover, the elevator system comprises a control means and a drive unit, both not shown, the control unit controlling the operation of the drive means and receiving detection data from the emergency detectors, the detection means for detecting presence of the guard member in a retracted position and the like. Finally, the control means is connected to a control panel (not shown) which allows to enter commands to the control unit.

The operation of the elevator system 1 according to the present embodiment will now be described. During normal operation of the elevator system, the guard member 12 is in its retracted position as shown in Figs. 2b) and 3b). In case of emergency, for example a technical mal-function, an accident, fire or the like, the control means detects the emergency and outputs a command to the retaining means 18 in order to release the guard member 12 from its retracted position. In the present embodiment, the control means stops the supply of electric energy to the electromagnet 18 such that the guard member 12 is released. As a result, the guard member 12 moves due to gravity from its horizontal, retracted position into its vertical, extended position where it may be locked or fixed by appropriate means. The guard member 12 now is ready to keep persons from falling into the hoistway 2.

After termination of the emergency state, for example after repair or maintenance works have been finished, the elevator system 1 can be brought back into operation. This can be done by activating the operation of the elevator system via the control panel. In such a case, the control means initiates an process for returning the guard member 12 from its extended position to its retracted position before the elevator system returns into its normal operation. For this purpose, the control means causes the drive mechanism to move the elevator cabin 10 into its lowest position inside the hoistway 2. In the course of the downward movement of the elevator cabin, the roll 38 of the lever arrangement 32 comes into contact with the inclined surface 34'of the rail (second, stationary operation part) 34 (Fig. 4). Under continued downward movement of the elevator cabin, the roll 38 moves along the inclined surface 34' such that the lever arrangement 32 rotates which, in turn, causes a rotation of the guard member 12 around its pivot joint 16.

The sequence of this operation is illustrated in Fig. 5. As can be seen in Fig. 5, the continued downward movement of the elevator cabin 10 causes the roll 38 to move into a position above the bottom part 14 of the elevator cabin and, at the same time, a rotation of the guard member 12 from its extended position to its retracted position. In the retracted position, the electromagnet 18 exerts an attraction force on the guard member 12 such that the guard member 12 is fixed in its retracted position. In this state, the detection means detects the presence of the guard member in the retracted position such that the control means may initiate the normal operation of the elevator system.