Abstract:
The invention provides an elevator having a car movable along guide rails mounted in a shaft. The elevator comprises an inspection control station mounted on top of the car and accessible via a movable control station cover, blocking means for selectively preventing movement of the car into a safety space within the shaft and actuation means for actuating the blocking means. The actuation means is configured for concurrent movement with the control station cover. Accordingly, a temporary safety space is automatically created within the shaft as the maintenance technician opens the control station cover to move the car using the inspection control station.

Description:
The present invention relates to the creation of a temporary safety space within a shaft of an elevator and in particular to a device that mechanically limits the travel of an elevator car to create the required safety space for maintenance personnel working within the elevator shaft. 
   BACKGROUND OF THE INVENTION 
   On the one hand there is continual pressure on elevator designers to reduce the space required for an installation within a building, but on the other hand the installation must meet industry standards by ensuring that an adequate safety space is provided in the overhead and pit of the shaft for maintenance personnel working in the shaft. Traditionally, these safety requirements have been met by providing an extended shaft having the appropriate safety spaces permanently installed above and below the travel path of the elevator car. 
   There have been recent proposals to reduce the space required by an elevator installation by removing the permanent safety spaces and instead creating temporary safety spaces only when required. U.S. Pat. No. 5,773,771 describes such a system using bolts that extend outwardly from opposing sides of the elevator car to prevent the car from moving into a particular zone or temporary safety space. When maintenance is to be carried out within the shaft, the technician mounts the roof of the car and pulls a rod at the side of the car to trigger the bolts into their extended position. The technician can then move the car at a reduced, inspection speed along the shaft using an inspection control station. The travel path of the car is restricted as the extended bolts engage with corresponding steel plates mounted at specific positions on the guide rails and the required temporary safety space is thereby established. 
   The objective of the present invention is to simplify the procedure for performing maintenance operations within the shaft of an elevator installation. In particular, the invention seeks to overcome the need of the maintenance technician to remember to manually activate the bolts before commencing inspection speed travel using an inspection control station mounted on the car. 
   BRIEF DESCRIPTION OF THE INVENTION 
   The present invention provides an elevator having a car movable along guide rails mounted in a shaft. The elevator comprises an inspection control station mounted on the car and blocking means for selectively preventing movement of the car into a safety space within the shaft. Access means are provided to selectively enable operable access to the inspection control panel and are configured to concurrently actuate the blocking means. 
   The invention also provides a method for creating a safety space in a shaft of an elevator having a car movable along guide rails mounted in the shaft. The method comprises the steps of mounting an inspection control station on the car and selectively preventing movement of the car into the safety space within the shaft using blocking means. Access to the inspection control station is selectively prevented such that accessing the inspection control station causes concurrent actuation of the blocking means. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is further described by way of the examples with reference to the accompanying drawings in which: 
       FIG. 1  is a schematic representation of an elevator according to a preferred embodiment of the present invention; 
       FIG. 2  is a perspective view of a portion of the inspection control station of  FIG. 1 ; 
       FIG. 3  is a perspective view of the arrangement of a first pivotal cam extendible from a side of the elevator car of  FIG. 1 ; 
       FIG. 4  is a perspective view showing the first cam in its extended position in engagement with a guide rail mounted buffer; 
       FIG. 5  is a perspective view of a second pivotal cam extendible from a side of the elevator car of  FIG. 1 ; 
       FIG. 6  is a front view of an operating panel within the elevator car according to a second embodiment of the present invention; 
       FIG. 7  is a side view of the operating panel of  FIG. 6 ; and 
       FIG. 8  is a front view of an alternative operating panel according to a third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An elevator  1  according to the present invention is shown in  FIG. 1  and comprises an elevator car  4  movable vertically along guide rails  3  mounted within a shaft  2 . The car  4  includes guide shoes  6  to ensure that the car  4  accurately follows the path of the guide rails. 
   During maintenance, a technician mounts the roof  5  of the car  4  and presses an emergency stop button (not shown). He can then move the car  4  at an inspection speed using the inspection control station  7 . As shown specifically in  FIG. 2 , the control station  7  includes a pivotal cover  8  mounted on hinges  9 . A lever  10  and support bracket  11  are mounted on the roof  5  alongside the control station cover  8 . The lever  10  is interconnected, and moves concurrently, with the cover  8 . The lever  10  is connected to an end of a central wire  13  of a first Bowden cable  12  while the sheath  14  of the Bowden cable  12  is fixed to the support bracket  11 . 
   At the other end of the first Bowden cable  12 , the central wire  13  is fixed to a first pivotal cam  15  (shown in  FIG. 3 ) and the sheath  14  is secured to a support bracket  15   a . The pivotal cam  15  is biased by a spring  16  towards an extended position shown in  FIG. 4  where the cam  15  extends from the side of the car  4  to engage with a buffer  18  fixed by a bracket  19  to the guide rail  3  and thereby prevents further upward motion of the car  4  into the overhead safety space  24 . When the first pivotal cam  15  assumes its retracted position the car  4  can travel unhampered along its normal travel path. 
   A second Bowden cable  17  is arranged in the same manner between the first pivotal cam  15  and a second pivotal cam  20  provided on the opposing side of the car  4 . As illustrated in  FIG. 5 , the second pivotal cam  20  is also biased by a spring  21  to an extended position where it extends from the side of the car  4  to engage with a buffer  18  fixed by a bracket  19  to the guide rail  3  and thereby prevents further upward motion of the car  4  into the overhead safety space  24 . In the retracted position of the second pivotal cam  20  the car  4  can travel unhampered along its normal travel path. Two safety contacts or switches  22  and  23  are provided alongside the second pivotal cam  20  to indicate when the cam  20  is in the extended and retracted positions, respectively. Since the first and second cams  15  and  20  are operated in tandem, an indication of the position of the second pivotal cam  20  is sufficient to indicate the position of the first pivotal cam  15 . 
   To carry out maintenance work from the roof  5  of the car  4 , the technician manually opens a landing door using a conventional triangular key. The safety chain of the elevator control is thereby broken and the elevator  1  is placed in a STOP condition. The technician then accesses the car roof  5 , presses an emergency stop button (thereby maintaining the STOP condition even if the landing door closes) and opens the cover  8  of the inspection control station  7 . The lever  10  moves concurrently with the cover  8  and through this action the central wires  13  of both Bowden cables  12  and  17  relax. Accordingly, the first and second cams  15  and  20  pivot into their extended positions under the spring biases. The safety contact  22  generates a signal to the elevator controller when the second cam  20  is in the fully extended position, and the elevator  1  is released from the STOP condition to an inspection mode whereby the technician can move the car  4  at an inspection speed within the shaft  2  using the inspection control station  7 . In the inspection mode the car  4  is prevented from entering the overhead safety space  24  since the pivotal cams  15  and  20  are in the extended positions and engage with the rail mounted buffers  18  if the technician attempts to move the car  4  upwards into the safety space  24 . 
   After the required maintenance has been carried out, the technician closes the control station cover  8  and the central wires  13  of both Bowden cables  12  and  17  are moved against the biasing force of the springs  16  and  21  and the cams  15  and  20  are thereby pivoted to their retracted positions. The safety contact  23  generates a signal for the elevator controller, returning the elevator  1  from the inspection mode into a STOP condition. Thereafter the technician leaves the shaft  2  through a landing door and activates a reset button which enables the elevator  1  to resume its normal operating mode. 
   It will be readily understood that the above arrangement for creating the necessary temporary safety space  24  in the overhead of the shaft  2  can easily be adapted to establish a similar safety space in the pit of the shaft  2 . Indeed, all that is needed are additional buffers  18  mounted on the guide rails  3  at the required level in the lower region of the shaft  2 . 
   Furthermore, although both of the pivotal cams  15  and  20  in the described embodiment are spring biased, it is clear the same effect can be reproduced using a single biasing spring  21  on the second pivotal cam  20  only, since any movement of the second cam  20  automatically carries over to first cam  15  through the interconnecting second Bowden cable  17 . 
   In a preferred embodiment the control station cover  8  is used to control access to the inspection control station  7 . However, it will be obvious to the skilled person that any other access means is equally applicable for implementing the present invention. For example, the inspection control station  7  may not have a cover  8 , in which case the inspection controls are otherwise made inoperable until the lever  10  has been moved to create the safety space. Alternatively, the inspection control station  7  may be configured so that it can only be activated by a key operated switch. In this case, the movement of the key operated switch can also be used to actuate the pivotal cams  15  and  20  into their extended positions and thereby create the required safety space. The key operated switch may be mechanically coupled to the pivotal cams  15  and  20 . Alternatively, movement of the key operated switch could complete an electrical circuit to actuate the pivotal cams  15  and  20 . 
     FIGS. 6 and 7  illustrate a further embodiment of the invention, wherein an operating panel  30  mounted in the interior of the car  4  has dual purposes. This embodiment is thought to be particularly useful with the elevator described in EP 1052212. In normal operation, it functions as a normal car operating panel whereby users register their desired destination using the pushbuttons  32  on the panel  30 . In maintenance situations, the technician can insert a key  36  into a key operated switch  34  on the side of the panel  30  transforming the panel  30  into a functioning inspection control station and simultaneously actuating the pivotal cams  15  and  20 . 
     FIG. 8  shows an alternative embodiment wherein the normal car operating panel  40  is transformed into a functioning inspection control station electronically by inputting a correct security code using the keypad  42  and thereby simultaneously actuating the pivotal cams  15  and  20 . 
   Although the invention has been described with specific reference to pivotal cams  15  and  20  as the means for creating the temporary safety space, it is obvious that the invention can utilise any other blocking means which selectively prevents movement of the car into a safety space within the shaft.