Abstract:
A machine includes a motor that includes a stator carrying a concentrated winding wound on teeth and a rotor rotatable about the stator. The rotor includes a tubular casing and permanent magnets, and a pulley coupled to the rotor.

Description:
FIELD OF THE INVENTION 
   This invention relates to machines for driving at least one cable. In embodiments, this invention is directed to providing a machine for driving an elevator cable. 
   BACKGROUND OF THE INVENTION 
   The axial size of such machines is a determining factor for the cost of installing elevators. 
   U.S. Pat. No. 4,960,186 discloses a machine in which a pulley is fixed on an end wall of the rotor, thus making it possible to use a pulley of a diameter that is smaller than the diameter of the rotor. 
   Machines having a disk-shaped rotor and a reduced axial size have been proposed, for example in U.S. Pat. No. 5,996,742. 
   U.S. Pat. No. 4,771,197 discloses a machine in which the grooves of a pulley are made around the rotor. European Patent EP 0,706,968 and German Patent DE 199 03 409 describe other machines. 
   SUMMARY OF THE INVENTION 
   In embodiments, this invention provides a machine which is relatively compact while offering mechanical and electrical performance that make it suitable for driving, for example, an elevator. 
   In some embodiments, the machine may include a motor including a stator carrying at least one concentrated winding wound on teeth; a rotor around the stator, the rotor including a tubular casing and permanent magnets; and a pulley coupled to the rotor. 
   The term “stator” designates the assembly of laminations and windings or coils constituting the stationary electrical portion of the machine. 
   Advantageously, the pulley covers the stator in part, and preferably it covers winding heads of the stator. 
   The machine maybe made to occupy a small amount of space, particularly in the axial direction. 
   In embodiments, a tubular casing of the rotor preferably includes a stack of superposed laminations. The stack of laminations may advantageously be maintained in compression by fasteners, such as screws which are engaged in the pulley. This disposition enables the fasteners to provide both for fastening the rotor to the pulley and for maintaining the cohesion of the stack of rotor laminations. 
   The pulley may have a peripheral portion with grooves formed therein for receiving the cables, and a portion for receiving rotor fasteners, said portion being made integrally with the peripheral portion, e.g. by casting material or by machining. The portion for receiving the rotor fasteners may cover the winding heads of the stator without covering the teeth of the stator. This can make it possible for the pulley to be made out of a solid material that conducts electricity without that leading to major losses by induced current. 
   The pulley may advantageously have passages to allow air to flow through it, thus making it possible to avoid using a specific fan driven by the shaft of the machine. 
   The air flow may sweep both the stator and a brake disk. 
   The machine may include a strip covering an axial free end of the rotor remote from the pulley. 
   The machine may include at least one parking brake. 
   The machine preferably is not overhanging by an end part (i.e. fixed in a cantilevered manner). Instead, the machine may be supported by at least one support at each end of the machine. 
   The machine may include bearings, such as a bearing on each side of both the pulley and the rotor, preferably on each side of both the grooves of the pulley and the magnets of the rotor, supporting the axial ends of a shaft of the rotor. The machine may include only two bearings or may include more than two bearings. 
   The machine may further include a sensor, for example an optic sensor, of the number of turns of the pulley and/or the rotor around the axis. 
   The pulley may be connected at an end remote from the stator to a ring for co-operating with jaws of a brake. 
   In some embodiments, the invention may also provide, independently or in combination with one or more of the above mentioned features, a machine for driving at least one cable, such as an elevator cable, the machine including a pulley and an electric motor; the electric motor including a stator and a rotor coupled to the pulley; the rotor being rotatable about the stator and including permanent magnets present on an inside face of a tubular casing which is directly secured to the pulley via one end. 
   In some embodiments, the invention may also provide, independently or in combination with one or more of the above mentioned features, a machine for driving at least one cable, such as an elevator cable; the machine including a motor including a stator, and a rotor around the stator; the rotor including a tubular casing and permanent magnets; and a pulley coupled to the rotor and partially covering the stator. 
   Embodiments of the invention also provide a system and method for driving an elevator, using a motor as described herein for driving a cable of the elevator. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will be described with reference to the following drawings in which like reference numerals refer to like elements and wherein: 
       FIG. 1  is a perspective view of one exemplary embodiment of a machine of the invention; 
       FIG. 2  is a fragmentary axial section view of a machine of  FIG. 1 ; 
       FIG. 3  is an axial half-section view on III—III of  FIG. 2 ; and 
       FIG. 4  is a cross-sectional view of a machine of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF EMBODIMENTS 
   The following detailed description of various exemplary embodiments of this invention may refer to one specific type of machine, a machine including a pulley and an electric motor for driving an elevator cable, for sake of clarity and familiarity. However, it should be appreciated that the principles of this invention, as outlined and/or discussed below, can be equally applied to other known or later developed machines, beyond the machine specifically discussed herein. 
     FIG. 1  through  FIG. 4  show an exemplary embodiment of a machine that incorporates features of the invention. The machine  10  shown in the figures includes a pulley  20  and a motor  30  for driving the pulley  20  in rotation about an axis of rotation X. 
   The motor  30  includes a stator  31  including a stack of superposed laminations  32 , the stack defining teeth  33  on which respective windings  34  are engaged. The laminations  32  are made of magnetic material, and prior to being assembled together, they may be insulated in conventional manner, e.g. with varnish. 
   The stator  31  is supported by a first end wall  36  which extends perpendicularly to the axis X and which rests on longitudinally-extending rails  37  for securing the machine to its support. 
   The laminations  32  are engaged on a guide  38  of axis X which is secured at one end to the first wall  36 . First wall  36  has the shaft  40  of the machine passing therethrough. The guide  38  serves to transmit the torque that acts on the stator laminations  32  to the first wall  36 . 
   The shaft  40  presents one end which is supported by bearings  41  mounted on the first wall  36 . 
   The other end of the shaft  40  rests on bearings  44  secured to a second end wall  46 . Second end wall  46  extends perpendicularly to the axis X and is supported by the rails  37 . 
   The pulley  20  includes a hub  21  which is secured to the shaft  40  and which turns therewith, and a peripheral portion  22  having grooves  23  formed therein, each serving to receive a respective cable C for driving an elevator. 
   In the embodiment shown in  FIG. 1  through  FIG. 4 , passages  24  are made between the peripheral portion  22  and the hub  21  in order to allow cooling air to flow and in order to lighten the pulley. 
   The pulley  20  is made to have a ring  25  at one end for co-operating with the jaws of a conventional parking brake  50  supported by the second wall  46 . The parking brake  50  supported by second end wall  46  can be seen more particularly in  FIG. 3 . 
   At its end opposite from the ring  25 , the pulley  20  has an end portion  28  for securing to the rotor  60 . 
   The rotor  60  includes a tubular casing  61  made up of a stack of laminations  62  held in compression by fasteners  63 , such as screws, which are engaged at one end  66  in the end portion  28  of the pulley  20  and which bear at the opposite end against the stack of laminations  62 . 
   On its radially inner surface, the rotor  60  also carries a plurality of permanent magnets  64  disposed in such a manner as to interact with the stator  31  so that, when the stator generates a rotating magnetic field, the rotor  60  tends to be entrained to rotate synchronously about the axis X. 
   The magnets  64  may be bonded to the circularly cylindrical inside surface of the casing  61  by, for example, an adhesive, with the magnets preferably being disposed in rows, each including a plurality of magnets juxtaposed along the direction of the axis X, these rows being spaced apart from one another by gaps  39 . 
   As apparent from the Figures, the rotor  60  may be supported solely by the pulley  20 , and may overlie the heads  34   a  of the windings  34  of the stator without overlying the teeth  33 . 
   The machine  10  may further include a cable protector  70 , as shown in  FIG. 3 . 
   Advantageously, and as shown in  FIG. 1  and  FIG. 2 , the machine may also include a strip  67  covering the free axial end  61   a  of the casing  61 , this strip  67  being secured to the first wall  36 . 
   Naturally, the invention is not limited to the above description. 
   For example, the pulley can be made with some other number of grooves, e.g., as a function of the type and characteristics of an elevator or other device to be driven. 
   As another example, where appropriate, the stack of rotor laminations may be replaced by a solid material, with the tubular casing of the rotor optionally being made integrally with the pulley. 
   The terms “including a” and “comprising a” appearing herein should be understood as being synonymous with “including at least one” unless specified to the contrary. 
   While this invention has been described with respect to specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the embodiments of the invention as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention.