Abstract:
A pitless elevator system removes a car buffer and machine, and other components where so equipped from under the elevator car such that the elevator car can be operated to a clearance between it and a floor of a hoistway of about three inches. The machine may be mounted on board the car or may be located elsewhere and the car buffer located in normal side clearance space. The system further provides a retractable toe guard to allow the car to bottom at the indicated distance from the floor. The system facilitates retrofit applications of elevators without the prior art drawback of digging a pit.

Description:
This is a division of application Ser. No. 09/296,885 filed Apr. 22, 1999 now U.S. Pat. No. 6,095,288, the contents of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to the elevator art. More particularly, the invention relates to an elevator system which is particularly conducive to retrofitability in structures without elevator pits as well as new construction where a pit is not desired or permitted. 
     2. Prior Art 
     In the elevator art it has been conventional for a very long period of time to build an elevator hoistway, i.e. the shaft in which an elevator car is moved upwardly and downwardly, with a pit. A pit is a continuation of the hoistway downwardly below the intended lowest level at which the elevator car will have duty. The lowest level may be a first floor or a basement, etc. Typically, a pit is about 4-5 feet in depth below the lowest elevator car level and thus requires a substantial amount of excavation of material at not insignificant cost. Moreover, the deeper a pit is dug the more likely it becomes that the water table in the area will be reached which further complicates matters. Where an elevator system is a retrofit in an existing structure, the excavating of a pit is complicated further and further increases expense. Additionally, the pit takes up space that could be otherwise employed. The latter interpretation occurs where an elevator stops a level above a basement and the pit is located in the basement. Digging is thus not specifically required for the pit itself but a portion of the basement is lost and the elevator car, in a conventional system, could not be lowered to the basement level. 
     A pit is conventionally required for elevator systems in order to house the over limit car buffer and pit sheaves, and to provide clearance for the elevator car entrance toe guard which can be up to two meters in length and is rigid. Toe guards are also commonly referred to as platform guards. Toe guards extend below the elevator car and block access to the hoistway in the event the elevator car is not leveled properly at a landing. The toe guard therefore requires in such a case at least two meters of clearance and preferably more to avoid bumping the bottom of the shaft when the elevator is at its lowest point. This could occur if insufficient space were left in the pit to receive the toe guard in the event the car continued too far downwardly in the hoistway (an over limit condition). 
     The foregoing limitations have been consistent drawbacks of the elevator art. In an era of ever increasing cost of space and construction, the art is in need of pitless elevator systems for both new construction and retrofit applications in existing structures. 
     SUMMARY OF THE INVENTION 
     The above-identified drawbacks of the prior art are overcome or alleviated by the pitless elevator system of the invention. 
     The invention simplifies new construction by eliminating the conventional need for a pit and facilitates the retrofitting of existing structures with elevators by obviating the need for the pit. 
     In order to avoid a pit, the elements traditionally housed therein must be relocated and otherwise modified to facilitate elevator system operation without the undercar clearance of the pit. The pitless elevator system of the invention includes one or more car buffers located in a portion of the side clearance space necessary in all elevator systems. The car buffers will in the event of over limit conditions of the car, contact strike angle(s) on the car to brake its movement. Since the car buffers are not located under the car, clearance therefor is not needed. Moreover, pit sheaves, if employed for the elevator roping configuration, are preferably nestled near or between the structural beam rails, and the machine is not placed underneath the car but is located elsewhere within the hoistway. Locations include on the car, in the tower of the hoistway, between the rails or on side clearance space. The location of the machine is not critical so long as it is not located under the car. 
     Another aspect of the system of the invention is a toe guard which requires virtually no clearance and is automatically or manually retractable under the bottom surface of the elevator car. The combination of features in the elevator system of the invention allows for pitless installation and greatly benefits the art. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
         FIG. 1  is a perspective view of the pitless elevator system of the invention with the elevator car illustrated at a second level to depict clearly one location of the car buffer and the clear floor of the hoistway; 
         FIG. 2  is another perspective view of the invention with the car at the first level; 
         FIG. 3  is an elevation view of a portion of the elevator car having a toe guard in the deployed condition; and 
         FIG. 4  is an elevation view of the toe guard of the invention in the partially retracted position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An elevator system  10  contains certain basic elements that are represented in the invention and illustrated in  FIGS. 1 and 2 . These elements include an elevator car  12  guided by at least one and preferably two guide rails  14  through the intermediary frame  16 . The system  10  further includes a machine  18 , shown as an on-board machine in the illustration but not limited as such, and several sheaves (discussed hereunder). A counterweight is illustrated as  20  and car buffers  22  are located on the floor  24  of the hoistway  26  in which car  12  is cycled, the buffers being placed outside of the area directly under the car  12  (also defined for purposes of this application as the elevator car footprint). 
     In order to achieve the desired beneficial result of the invention and provide a functioning elevator system without a pit, all of the conventional residents of the pit must be relocated to clearance spaces around the portion of hoistway  26  occupied by car  12 . In a preferred embodiment the arrangement is as illustrated in  FIGS. 1 and 2  wherein it will be appreciated that car buffers  22  are located in the foreground of the drawing and background of the drawing almost hidden behind the background rail  14  correspond to side clearance space for the elevator system. It will also be appreciated that the pit sheaves used in the particular roping configuration shown are located in such clearance space. It is noted that pit sheaves are not a necessary part of the invention, but if used must be located outside of the elevator car footprint. Considering car buffers  22 , it is axiomatic that since they are not located underneath the car  12  as would conventionally be the case (in the conventional case only one would be used), it must have provision for a surface that will contact the car buffer in the event of an overlimit condition. For this purpose a strike angle  28  is provided in a secured relationship to frame  16 . 
     Strike angle  28  is preferably constructed of a material and configuration to become a structural member and support the full load of the elevator car  12  in the event of an overlimit condition resulting in contact between strike angle  28  and car buffer  22 . In one preferred embodiment, the strike angle  28  is constructed of ½ inch thick steel which is fastened in a structural manner to frame  16 . Frame  16  further provides, as is common, the connection to cables for lifting the elevator car. In one preferred embodiment of the invention, car buffer  22  stands approximately 18 inches tall. In such an embodiment the strike angle  28  will be configured to stop at about 21 inches above the floor  24  of hoistway  26 . Thus, a 3 inch space buffer will exist between the strike angle  28  and car buffer  22 . This is beneficial since in the event a very small overrun occurs, the strike angle  28  will not come in contact with buffer  22 . In this condition, where strike angle  28  is about 21 inches above floor  24 , a base  30  of elevator car  12  will preferably hover about 3 inches above floor  24 . 
     Another possible resident of the pit is pit sheaves  30 . Pit sheaves may or may not be employed in elevator systems as dictated by roping configurations. Where pit sheave(s) are used they must not be located under the elevator car in accordance with this invention. In the drawing figures appended hereto, one of the pit sheaves  30  is fully visible and the other is nearly fully obscured by foreground rail  14 . Pit sheaves  30  have been relocated in the system of the invention to a clearance area between car  12  and rails  14 . In this position the elevator rope  32  is easily alignable and the sheaves  30  do not limit the downward movement of the car  12 . 
     Another component of a systems of a conventional variety that is addressed in the system of the invention is toe guard  34 . Conventionally, as stated hereinbefore, the toe guard is rigid and long and therefore requires a large amount of vertical clearance located below the lowest level of car  12 . In pit elevator systems such clearance is available in the pit, however in the pitless elevator system of the invention, there is no clearance space available into which the toe guard may extend when the car is at the lowest level. 
     Referring to  FIGS. 3 and 4 , a retractable toe guard  34  of the elevator system of the invention is illustrated in  FIG. 3  in the deployed position with the car  12  at a landing  35  and in  FIG. 4  in a partially retracted position with the car  12  at the lowermost landing  35  (the fully retracted position is shown in phantom lines in  FIG. 4 ). The retractability of the guard  34  allows the full function of a toe guard while obviating the need for substantial vertical clearance space. 
     Guard  34  is hingedly connected to car  12  at a suitable member  36  through preferably a spring hinge  38  although it will be appreciated that any type of hinge arrangement may be substituted if desired such as a living hinge, plates and pin hinges, etc. Where a spring hinge  38  is employed, toe guard  34  will automatically assume the deployed position of  FIG. 3  in the absence of an impetus to urge toe guard  34  into the retracted position (illustrated as partially retracted in  FIG. 4 ). One contemplated form of impetus is kick member  40  which provides an angular surface  42  aligned with the toe guard  34  in the deployed position ( FIG. 3 ). Upon toe guard  34  contacting surface  42  it is urged toward the retracted position. Once the toe guard  34  has begun moving to the retracted position the continued downward movement of the elevator car  12  will continue to cause the toe guard  34  to collapse into the retracted position. Surface  42  is preferably about 45° inclined relative to a plane in which toe guard  34  resides when in the fully deployed position. In order to assist the desired movement of toe guard  34 , a distal end  44  thereof comprises a roller  46  preferably on each end of guard  34 . Roller  46  is mounted to offset  48  in guard  34  to increase angular movement of guard  34  when in contact with kick member  40 . Roller  46  is connected of offset  48  via pin  50 . Roller  46  also reduces noise associated with moving guard  34  into the retracted position. It will be appreciated that although slightly more noise may be developed by toe guard  34  without roller  46  during retracting (guard  34  will scrape on floor  24 ) the device will still function as desired. 
     The retractable toe guard  34  thus enables the pitless elevator system of the invention and additionally facilitates inspection of the elevator car and hoistway without lifting the car as high as would otherwise been necessary with a rigid toe guard. The function of inspection is augmented by an arm  52  which may be manual or powered to retract toe guard  34  or to deploy toe guard  34  (in applications where the toe guard spring hinge does not automatically deploy toe guard  34 ). 
     The elevator system of the invention combines the benefits of the individual features of the car buffer position, the pit sheave position and the retractable toe guard to render pitless operation possible and reliable and thereby reduces the cost of new construction elevator systems and enables retrofit systems. 
     While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.