Abstract:
A battery powered elevator system in which the battery and power electronics needed to connect the battery to the machine driving the elevator system are mounted in close proximity within the hoistway of the elevator system to minimize power transmission losses.

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to elevators, and more particularly relates to battery powered elevators. 
     BACKGROUND OF THE DISCLOSURE 
     Elevators are well-known devices for navigating people and cargo up and down within multi-story buildings. Traditionally, people and cargo are carried in elevator cars which navigate through hoistways provided vertically within the buildings. Each car is mounted on a plurality of rails to allow for linear translation of the car through the hoistway and is powered by a machine such as an electric motor connected to the car by way of belts, cables, or the like. A counterweight is also typically mounted on adjacent rails to facilitate the smooth movement of the car through the hoistway. The machine, as well as the other mechanical components of the elevator such as a sheave, governor or the like, is typically mounted on a bedplate provided at the top of the hoistway. 
     With relatively large elevators, the power and power electronics for energizing the machine are typically provided within a machine room provided at the top of the building. Alternatively, such equipment can be provided within a landing cabinet provided somewhere in the building other than the hoistway. This facilitates maintenance of the system, as well as connection of the building power grid and/or utility power grid to the machine, or if in a relatively large installation, machines for multiple elevators. 
     In more recent applications, the power used to energize the machine is not fixed or tied to an existing utility grid, but rather is provided by way of self-contained power sources, such as batteries. Among other things, such batteries lower power draw from the building power grid and often times are more reliable than utilities or generators in that they are not dependent on the utility power grid being up and running at all times. 
     While effective, as elevator systems have typically employed the aforementioned machine rooms or landing cabinets outside of the hoistways, with existing battery-powered elevator systems, the batteries are therefore currently housed outside the hoistway as well. Typically, the inverter and other power electronics used for the system are also mounted outside of the hoistway. 
     SUMMARY OF THE DISCLOSURE 
     It has been discovered that known elevator systems possess inherent inefficiencies resulting from the physical configuration of the systems&#39; components. Furthermore, it has been discovered that these inefficiencies may be mitigated or eliminated by utilizing any of the alternate configurations disclosed herein. By minimizing the physical length of the large gauge lines over which low voltage—high current electrical power signals are transmitted, it is possible to eliminate the significant efficiency losses, elevator performance issues, and the battery life issues inherent in the known elevator systems. 
     In accordance with one aspect of the disclosure, an elevator system is disclosed which may comprise a hoistway, a passenger car movable within the hoistway, a machine operatively connected to the passenger car to move the passenger car within the hoistway, and a battery operatively connected to the machine and mounted within the hoistway. Although the exemplary embodiments are described as containing batteries, a person skilled in the art at the time of the invention having the benefit of this disclosure would have understood that the disclosed batteries may be replaced with other power sources without departing from the scope or spirit of the invention. The battery supplies all the power needed by the machine to move the passenger car under normal operating conditions of the elevator system. 
     In accordance with another aspect of the disclosure, an elevator system is disclosed which may comprise a hoistway, a plurality of rails mounted in the hoistway, a car moveably mounted on at least one of the rails, a counterweight moveably mounted on at least one the rails, a bedplate connected to the rails on top of the hoistway, a machine mounted to the bedplate and operatively connected to the car, and a battery connected to the machine to power the machine, wherein the battery is mounted on the bedplate. 
     In accordance with another aspect of the disclosure, a method of operating an elevator is disclosed which may comprise providing a passenger car moveably mounted within a hoistway, driving the passenger car up and down within the hoistway with a machine, powering the machine entirely with a battery during normal operation, and mounting the battery within the hoistway. 
     While the exemplary embodiments are described as separate embodiments, a person skilled in the art at the time of the invention would have understood that many of the disclosed features are suitable for use in any of the embodiments. For example, any of the embodiments may additionally comprise: a battery as the power source; a motor as the machine; a bed plate to which the power source, the machine, or other electronics (such as an inverter) may be mounted; a counterweight to which the power source may be mounted; and/or a plurality of lintels to which the power source may be mounted. Similarly, a method according to any of the disclosed embodiments may also comprise similar features. 
     These and other aspects of the disclosure will become more readily apparent upon reading the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an elevator system constructed in accordance with the teachings of the disclosure; 
         FIG. 2  is a side view of one exemplary embodiment of an elevator system constructed in accordance with the teachings of the present disclosure; and 
         FIG. 3  is a schematic representation of alternative embodiments of elevator systems constructed in accordance with the teachings of the disclosure. 
     
    
    
     While the following disclosure will be made with reference to certain exemplary embodiments, it should be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its scope. It is intended that the disclosure not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this disclosure, but that the scope of the invention should include all embodiments falling with the spirit and scope of the appended claims. 
     DETAILED DESCRIPTION 
     Referring now to the drawings, and with specific reference to  FIG. 1 , an elevator system constructed in accordance with the teachings of the disclosure is generally referred to by reference numeral  20 . As shown therein, the elevator system  20  may include a hoistway  22  defining a vertically-disposed, open channel through a multi-story building (not shown) employing the elevator system  20 . The elevator system  20  may further include a plurality of rails  24  extending from a bottom or pit  26  of the hoistway  22  to a top  28  of the hoistway  22  where the rails  24  terminate in a connection to a bedplate  30 . The rails  24  provide structure to facilitate linear movement of an elevator car  32  through the hoistway  22 . Moreover, rails  33  provide a similar mechanism by which a counterweight  34  can also move linearly through the hoistway  22 . 
     In order to drive the car  32  through the hoistway  22 , a machine  36  is employed. The machine  36  may be provided in the form of an electric motor or any other form of prime mover. As shown in conjunction with  FIG. 2  as well, the machine  36  may include an output shaft  38  on which one or more sheaves  40  are mounted. Belts, cables, or other looped power transmission devices  42  are then trained around the sheave  40  for connection to the passenger car  32  at a first  44 , and to the counterweight  34  at a second  45 . 
     Referring now to  FIG. 2 , it may be seen that in accordance with the teachings of the present disclosure, the bedplate  30  can also be used to mount the power source and power electronics for the machine  36 . In the embodiment shown in  FIG. 2 , a battery  46  and inverter  48  or other drive mechanism are mounted directly to the bedplate  30 . In the depicted embodiment, the machine  36  and sheave  40  are mounted to a top surface  50  of the bedplate  30 , with the battery  46  and drive  48  mounted to a bottom surface  52  of the bedplate. In another embodiment, the bedplate is hollow, and the power source is mounted within the bedplate. However, in alternative embodiments, it is to be understood that the machine  36 , battery  46 , and inverter  48  can be mounted in different positions on or around the bedplate  30 . What is of importance is that the distance over which the power needs to be communicated from the battery  46  to the machine  36  be minimized so as to avoid efficiency losses therebetween. 
     Moreover, in still further alternative embodiments, the battery  46  and inverter  48  need not be mounted directly to the bedplate but rather could be mounted elsewhere within the hoistway  22  while still providing significant advantages over current elevator systems in which the battery  46  and inverter  48  are mounted outside of the hoistway. For example, as shown best in  FIG. 3 , the battery  46  and/or inverter  48  could be mounted in the pit  26 , on the counterweight  34 , on the car  32 , on a door lintel  54  provided at each floor at which the elevator stops, on a hoistway wall  56 , on a ceiling  58  of the hoistway  22 , or anywhere else within the hoistway  22 . 
     Again, a primary concern is that the transmission distance over which the high current signals are transmitted is minimized to reduce power transmission losses. For example, such losses can generally be calculated using the equation: P 1 =I 2 R, wherein P 1 =power loss, I=current, and R=resistance. To put such losses into practical perspective, traditional 1000 kg elevator cars moving at 1 meter per second typically have a peek current draw of approximately 225 amps. In order to safely transmit currents of this magnitude, 0 or 00 gauge wire is generally used. Such wires (or conductors) not only cost several dollars per meter, but two such connectors are typically required between the battery  46  and the inverter  48 , and three are typically required between the inverter  48  and machine  36 . By reducing the distances over which these conductors have to navigate, the resistance R is reduced, resulting in less power transmission losses. Additionally, by locating the battery  46  closer to the machine  36  and inverter  48 , less wire will be required. 
     From the foregoing, it can be seen that the present disclosure sets forth an improved elevator system which enables batteries to be used as the power source for the elevator at greatly improved efficiency levels as compared to previously known elevator systems. By mounting the battery and power electronics inside the hoistway, the distances over which the electrical power must be communicated is greatly reduced. This can be done, for example, by placing the battery and inverter directly on a bedplate and thus directly adjacent to the machine. Additionally, the battery and inverter may be mounted at alternative locations in the hoistway, such as, but not limited to, in the pit, on the counterweight, on the car, in the overhead, on a hoistway wall, on the hoistway ceiling, or on the door lintels.