Abstract:
The invention relates to an air-cooled electric motor with a substantially cylindrical frame, closed by a front bottom and a rear bottom carrying bearings thereon for support of the drive shaft. The rear bottom extends in a peripheral wall projecting outwardly away from the frame wall and in substantial alignment therewith, to the free edge of said peripheral wall a cover being applied to delimit a chamber adapted to receive electric elements complementary to the motor.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to electric motors, in particular motors provided with a frame-cooling system at its generally finned outer wall.  
           [0002]    Such motors are equipped with complementary electric components, such as terminal board for connection to the power supply, starting capacitor, possible switches or protection devices against overcurrents and the like.  
           [0003]    In a traditional configuration, a box-shaped seat is applied to the outside of the frame; said seat radially projects from the frame and one or more of the above components are housed therein, depending on requirements. The radial projection of this box-shaped seat gives rise to many drawbacks when the motor is to be mounted within limited spaces, also because it constrains the angular positioning of the motor that loses its axial symmetry, i.e. its generally cylindrical configuration. In addition, in forming the frame a base is to be provided for positioning and anchoring of the box-shaped seat, which will bring about complications in the configuration of the forming moulds and, above all, will make it impossible to position the projecting box in a manner different from the foreseen one, when said box hinders positioning of the motor in the apparatus where said motor is required.  
           [0004]    It is an aim of the invention to obviate the above drawbacks by providing an electric motor with forced air cooling, in the frame of which a housing for complementary electric components is formed without the radial overall dimensions of the motor being altered. It is a further aim of the invention to house such components in a still more protected manner than allowed by many known embodiments.  
         SUMMARY OF THE INVENTION  
         [0005]    For the purpose, in accordance with the invention the electric motor has the features recited in claim 1. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    For better explaining the essential features of a motor in accordance with the invention and the advantages it offers, exemplary embodiments will be described hereinafter with the aid of the accompanying drawings. In the drawings:  
         [0007]    [0007]FIG. 1 shows a diagrammatic view in partial longitudinal section of a motor in accordance with the invention;  
         [0008]    [0008]FIG. 2 is an overall axonometric view of an alternative embodiment of the device of the invention;  
         [0009]    [0009]FIGS. 3 and 4 show a front view and an axonometric view respectively of an element of the device of the invention;  
         [0010]    [0010]FIG. 5 shows an axonometric view of a second alternative embodiment of the device of the invention;  
         [0011]    [0011]FIGS. 6 and 7 show a front view and an axonometric view respectively of an element of the alternative embodiment in FIG. 5.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    With reference to the drawings, as clearly seen in FIGS. 1 and 2, the motor comprises a frame  10  of generally cylindrical shape. One end of frame  10  is closed by a front bottom  11 , the other end by a rear bottom  12 . These bottoms are fastened to the frame ends in known manner, by screws for example.  
         [0013]    The outer wall of frame  10  is preferably externally provided with longitudinal fins  30  to increase heat dissipation. Mounted within the frame, as traditional, is the motor stator, of any known type and configuration, partly diagrammatically shown at  31 .  
         [0014]    The motor comprises rotor  13 , the shaft  14  of which is supported by bearings  15  and  16  mounted on bottoms  11  and  12 , respectively.  
         [0015]    Coming out of bottom  11 , of any traditional configuration, there is the end of shaft  14  designed to be connected to any device driven by the motor, through an appropriate mechanical coupling.  
         [0016]    The configuration of bottom  12  is, on the contrary, critical for achievement of the aims of the invention. It comprises a transverse wall  17  for closure of the frame, which wall receives the bearing  16  and a circumferential wall  18  jutting out away from the frame and substantially constituting an extension of the frame wall.  
         [0017]    The transverse wall  17  is passed through by the end of shaft  14 , and a sleeve  19  also jutting out from said transverse wall surrounds shaft  14  without contacting it. The generally cylindrical wall  18  together with sleeve  19  identify an annular chamber or space  32  closed by a cover  20  also passed through contactless by shaft  14 .  
         [0018]    A cooling fan  21  is fastened to the end of shaft  14  coming out of cover  20 , said fan being covered by a cap  22 . The central portion  23  of this cap is provided with openings for passage of the air sucked by fan  21 . The air is peripherally ejected through the annular opening formed between the cap and the substantially continuous wall consisting of frame  10  and the wall  18  of bottom  12 .  
         [0019]    It is apparent that the motor in this way is provided with a completely closed annular chamber  32  in which the required complementary elements for motor equipment can be inserted, the overall dimensions of which are diagrammatically denoted at  33 .  
         [0020]    In wall  18  windows can be formed on which complementary elements susceptible of being accessible or operated from the outside are mounted, a bushing for passage of the power cord or a switch connected to the conductors for powering the motor, for example. Obviously, corresponding openings are formed in cap  22 . By way of example, a switch housed in a corresponding opening of wall  18  is diagrammatically shown at  34  in FIG. 1 and two switches  34   a  and  34   b  are shown in FIG. 2.  
         [0021]    Openings can also be provided, possibly closed by flexible waterproof baffles, when elements to be manually operated from the outside are wished to be mounted in the chamber, such as commands for protection reset, switches or the like that are mounted within chamber  32 . If necessary cap  22  too will be provided with passage openings, as can be clearly seen in the different figures.  
         [0022]    Obviously, the longitudinal sizes of the chamber are defined by the overall volume and overall dimensions of the elements to be received therein, measurement of which can be easily established through definition of the length of wall  18  and sleeve  19  in the axial direction of the motor. The motor in accordance with the invention appears to have the minimum radial dimensions required by the motor itself, thereby facilitating mounting of same in sacrificed positions. The complementary elements, in addition to being received without taking too much room in a radial direction, are also enclosed in a well protected housing, even water-tight against accidental projections of liquid splashes.  
         [0023]    In the embodiment shown in FIGS. 2, 3 and  4 , in space  32  a housing can be provided for the starting capacitor  5 , the release coil  6  operable by an emergency key  7 , and also a significant portion of the on-off keys  34 . Access to the inside of space  32  takes place by a fairlead  35  of known type.  
         [0024]    In FIGS. 5, 6 and  7  it is shown another particular embodiment of the invention in which a terminal board  37  is used which is placed within space  32 . In this case a box-shaped seat  36  is formed at a lateral portion, said seat including a closing cover  38  which is advantageously hermetically sealed and opening of which obviously enables access to the terminals of the terminal board  37 . In this case as well at least one fairlead  35  is envisaged for access to the inside of the chamber.  
         [0025]    Advantageously, a hole  39  is advantageously also present on wall  18  to enable passage of an electric plug  40  held in place by a fork  41  located close to the inner surface of said hole.