Abstract:
An elevator has a car that moves along at least one guiderail in a hoistway and the car is supported by at least one suspension rope that is driven by a drive unit. The drive unit has a drive motor that rotates rope sheave over which the suspension rope passes. The drive unit is located in an upper section of the hoistway and projects over at least part of the car. To assure safe access to the drive unit when the dimensions of the hoistway are efficiently minimized, the car has a closable opening in the roof through which the drive unit is accessible.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates an elevator having a car that moves along at least one guiderail in a hoistway, and having at least one suspension rope that supports the car, and having a drive unit which has at least one drive motor with a traction sheave driven by it and working in conjunction with the one suspension rope at least, the drive unit being located in an upper section of the hoistway and projecting over at least part of the car. 
     From the technical article entitled “Aufzüge ohne Triebswerkraum” (“Elevators with no Machine Room”) published in “Lift-Report” issue March 1998, an elevator without a machine room is known in which the drive unit is located on supports that are fastened to a hoistway wall in an upper section of the hoistway. Maintenance work is carried out on the drive unit from the roof of the elevator car. So as to be able to observe the drive unit. even when it is in motion, an installation platform is proposed which can be installed from a maintenance platform when required. This elevator requires relatively high hoistway headroom above the car. Furthermore, installing the maintenance platform, or installation platform, in the hoistway is relatively complicated. 
     SUMMARY OF THE INVENTION 
     Taking the above-described elevator as the starting situation, the purpose of the present invention is to propose an elevator which, while making good use of the space in the hoistway, meaning having a low hoistway height and small hoistway cross-section, assures safe access to the drive unit, especially if the car is jammed high in the hoistway. 
     To fulfil this purpose according to the invention, on an elevator of the type mentioned above, it is proposed that the car have a closable opening in its roof through which the drive unit is accessible. 
     With the elevator according to the invention, maintenance work is carried out from inside the car by use of a maintenance platform located inside the car. The closable opening provided in the roof of the car makes the motor accessible to a service mechanic. 
     The accessibility of the drive unit above the car is assured even when the car is jammed high in the hoistway. The dimensions of the opening in the roof can vary. In particular, the opening in the roof can comprise the entire car roof, thereby affording good access to the drive unit from all sides. 
     A significant advantage of the elevator according to the invention is that in addition to good use being made of the cross-section of the hoistway, the height of the hoistway can also be kept very low, because maintenance work can be carried out from inside the car. Since the drive unit of the elevator according to the invention is not passed by the car, drive units of varying construction and dimensions can be used, thereby giving great flexibility. In particular, drive motors with or without gears can be used according to choice. The elevator concept according to the invention can be used with various arrangements of suspension ropes. In particular, by means of return pulleys under the car, the suspension rope can be made to pass beneath the car, or instead of a traction sheave a winding drum can be used. The drive concept according to the invention can also be used on so-called rucksack-type elevators in which the car is guided on one side only. Since the drive unit is located in the upper section of the hoistway, which is also known as the headroom, different methods of fastening the drive unit can be used. For example, the drive unit can be fastened either standing on, or suspended from, transverse beams supported between the hoistway walls. 
     In an advantageous development, the opening in the roof excludes the area over which the motor projects. Here, the opening in the roof has such dimensions, and is so positioned, as to ensure provision of adequate safe space for the head and upper part of the body of the service mechanic standing in the car, and to avoid crushing parts of the body between the car roof and drive unit in all positions of the car. 
     It is advantageous for the opening in the roof to be closable by means of a lockable flap. 
     In an advantageous further development, the flap is connected to an unlocking device that is secured against unauthorized access. This unlocking device can be connected to a switching device in the switchbox that is accessible only to the service mechanic. In an advantageous further development, it is proposed that the flap be constructed so as to be detachable from the car roof and usable as a maintenance platform or part thereof. For example, the flap can be used as the tread surface of the maintenance platform. Further, the flap can have foldout supports so that in the detached state it can be converted into a maintenance platform. The maintenance platform can also be stepped, and have several tread surfaces of different heights. 
     In another advantageous development the flap is fastened to a supporting device on the roof of the car by means of which the flap can be moved into a maintenance position parallel to the roof of the car. The supporting device can have, for example, holding members constructed in the form of scissors. 
     An advantageous development has at least one stop to ensure a minimum clearance between the car and the drive unit. This stop can be constructed as a buffer that operates in conjunction with the counterweight. 
     In an advantageous development of the invention the drive unit is supported on at least one beam which rests on a hoistway wall, or on guiderails of the car, or on guiderails of the counterweight. 
     In an advantageous further development the one suspension rope at least passes over return pulleys under the car. 
     The drive unit can be constructed with gears, particularly planetary gears. As already mentioned earlier, a significant advantage of the elevator concept according to the invention is that there are no restrictions on the dimensions of the drive unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
     FIG. 1 is a schematic longitudinal cross-sectional view through a hoistway with a first exemplary embodiment of an elevator according to the present invention; 
     FIG. 2 is cross-sectional view as if taken on the line  2 — 2  in the FIG. 1 with the car flap closed; 
     FIG. 3 is a cross-sectional view similar to the FIG. 2 showing another embodiment of the elevator according to the present invention; and 
     FIG. 4 is a longitudinal cross-sectional view through an elevator car of a further exemplary embodiment according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a schematic longitudinal cross-sectional view through an elevator hoistway  11  bounded on opposed sides by a pair of hoistway walls  12   a  and  12   b  that are essentially parallel to each other, at a bottom by a hoistway floor  18  and at a top by a hoistway ceiling  13 . In the hoistway  11 , there is a car  10  of the elevator for the purpose of transporting passengers. The hoistway  11 , which extends over several stories, has on each floor hoistway doors (not shown in the drawing) that can be traveled to by the car  10 . 
     To impart motion to the car  10 , the elevator has a drive unit  19  located in the upper section of the hoistway  11  in the so-called headroom. The drive unit  19  has a drive motor  21  with a drive shaft that rotationally drives a rope sheave  20 . To provide support to the drive unit  19  there are two beams  22  that are parallel to each other and whose ends are fastened to opposite walls of the hoistway  11 . 
     The car  10  is supported by a set of suspension ropes  14 , only one of which is illustrated schematically in the drawing. The suspension rope  14  has a first end that is fastened to an anchor  29  in the upper section of the hoistway  11  close to the hoistway wall  12   b.  Starting from the anchor  29  the suspension rope  14  passes over a pair of diverter pulleys  30   a  and  30   b  mounted on an underside of a floor  10   a  of the car  10  to the rope sheave  20  driven by the drive motor  21 . After passing over the rope sheave  20 , the suspension rope  14  passes to a counterweight return pulley  16  that is fastened to a counterweight  15 . After passing over the counterweight return pulley  16  the suspension rope  14  passes back to an anchor (not shown in the drawing) which is in the upper section of the hoistway  11 . 
     As can be seen in the FIG. 2, the car  10  is guided on two guiderails  28  that run in the longitudinal direction of the hoistway  11 . The counterweight  15  is also guided on guiderails  28  that are not shown in more detail. This view shows particularly well that an axis  23  of the drive motor  21  is positioned essentially perpendicular to the hoistway wall  12   a.  The rope sheave  20 , on the other hand, rotates in a plane parallel to the hoistway wall  12   a.    
     Since the drive unit  19  is located in an upper section of the hoistway  11  which the car  10  does not pass, the dimensions of the car can be chosen in such a manner that essentially the entire cross section of the hoistway can be used. Furthermore, good use is made of the hoistway height without additional safety clearances due to the car  10  having a roof  10   b  in which there is formed an opening  24  that can be closed by means of a flap  27 . To prevent improper opening, the flap  27  has an unlocking device  32  that is secured against unauthorized access. This prevents passengers from opening the flap  27  and climbing out of the car  10  during travel. The unlocking device  32  can, for example, be connected to a switchbox of the elevator that is accessible only to a service mechanic  25 . 
     FIG. 1 shows the car  10  in an operational status in which the car is in the maintenance position. The service or maintenance mechanic  25  uses a manual control to move the car  10  until it is close to the drive unit  19 . The counterweight  15  cooperates with a stop  17  that take the form of a buffer on the hoistway floor  18 . Contact between the counterweight  15  and the stop  17  terminates upward travel of the car  10 . This safely prevents contact between the car  10  and the drive unit  19 . 
     As can be seen from both FIG.  1  and FIG. 2, the opening  24  in the roof  10   b  does not extend laterally as far as the drive unit  19 . Consequently, the opening  24  excludes an area  10   c  of the car  10  over which the drive unit  19  projects. 
     To carry out installation or maintenance work, a maintenance platform  26  is placed on the floor  10   a  inside the car  10  beneath the opening  24 . The flap  27  can be removed from the opening  24  and placed on the floor  10   a  to serve as a tread surface. The maintenance platform  26  can be constructed to have steps, and have several tread surfaces of different height. The service mechanic  25  can then stand on the maintenance platform  26  and carry out maintenance work on the drive unit  19  through the opening  24 . Due to their position, all parts of the drive unit  19  are then easily accessible to the service mechanic  25 . 
     In the exemplary embodiment shown in the FIG. 4, the flap  27  is hung on a supporting device  33  that is fastened to the roof  10   b  of the car  10 . The supporting device  33  has holding members  34  that are constructed in the form of scissors, and onto whose free lower end the flap  27  is fastened. FIG. 4 shows the maintenance position in which the flap  27  has been moved from the opening  24  into the inside of the car  10  by the maintenance mechanic  25 . In this position the maintenance mechanic  25  can use the flap  27  as a maintenance platform, and carry out maintenance work on the drive unit  19  through the opening  24  in the roof. In the closed position, shown by a broken line, the flap  27   a  closes the opening  24  in the roof  10   b  of the car. 
     FIG. 3 shows a further exemplary embodiment illustrated by means of a cross section similar to FIG.  2 . To support the drive unit  19  there is a bracket  36  that is supported at its free end by parallel guiderails  35  of the counterweight  15 . The drive unit  19  projects over part of the car  10 . The drive unit  19  is easily accessible through the opening  24  in the roof. 
     Since maintenance work is carried out from inside the car  10 , and not from the roof  10   b  of the car, there is no need with any of the exemplary embodiments for a special safety clearance in the upper part of the hoistway  11 , which results in optimal utilization of the hoistway height. 
     Furthermore, with this elevator concept, any drive units  19  with different dimensions can be used. These include traction sheave drives with or without gears, winding drums, hydraulic drives, or linear motors. Moreover, the elevator concept according to the invention can also be used for other arrangements of suspension ropes. Common to all these variants is that the arrangement of the drive unit  19 , and execution of maintenance work through a closable opening  24  in the roof  10   b  of the car  10 , result in very good utilization of the hoistway  11  in both the horizontal and longitudinal directions. 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.