Abstract:
An electric motor having a rain baffle which is supported relative to and within the motor housing to prevent rain or the like which may enter ventilation outlets in the housing from contacting the rotor shaft bearing and the electrical components positioned within the housing. The rain baffle is also supported relative to and within the motor housing to allow air used to cool the motor to pass around the perimeter of the baffle and out the ventilation outlets in such a way as to substantially minimize the exhaust air from being recirculated back into air inlet vents in the housing.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to electric motors incorporating an internal baffle to protect components housed within the motor from exposure to rain, sleet, snow or other contaminants which may enter the motor through ventilation openings. 
     BACKGROUND OF THE INVENTION 
     Many electrical motors for outdoor applications require internal baffles to inhibit water or other contaminants, which may enter openings or vents that allow cooling air to travel through the motor, from contacting the rotor, electrical windings or other electrical components housed within the motors. It is generally known to provide a funnel shaped baffle within a motor housing near air outlet vents in the housing. If water or some other contaminant enters through the outlet vents, the baffle prevents the water or other contaminants from reaching the electrical components, particularly the rotor and electrical windings. 
     As generally understood, thermal protection of an electric motor is nearly as important as the amount of power produced by the motor. In other words, if a motor is not sufficiently cooled during operation, the motor could overheat, thereby possibly damaging the motor. Illustrated in FIG. 3 is a known electric motor  10  including a housing  12  having therein an inlet vent  14  and an outlet vent  26 . A funnel shaped baffle  34 , which is press-fit into the housing, is positioned near the outlet vent  26  to inhibit water or other contaminants which may enter through the outlet vent  26  from reaching the internal electrical components, such as the stator winding  18  and rotor  22 , of the motor  10 . The motor draws cooling air in (representatively shown as arrow A) through the inlet vent  14  and guides the air (representatively shown as arrows B and C) through the motor  10  to cool internal components. The air passes through the baffle  34  (as shown by arrow D), prior to exiting the outlet vent  26 . The motor also includes an end frame  38  and a rotor shaft bearing  46 . 
     SUMMARY OF THE INVENTION 
     As can be appreciated, it is desirable for the temperature of the intake air to be less than the temperature of the exhaust air. A problem with the known funnel baffle  34  design shown in FIG. 3 is that it sometimes causes hot exhaust air to be recirculated back into the air inlet vent  14 , thereby reducing the cooling efficiency of the motor. As shown in FIG. 3, as the heated air passes through the baffle  34 , the air undergoes a change of flow direction, typically an abrupt 180° turn (see arrow D in FIG.  3 ), prior to exiting the outlet vent  26 . The sudden change in the direction of air flow results in a pressure loss which reduces the total amount of air flow. Another disadvantage of the sudden change in the direction of air flow is that the abrupt 180° turn directs the hot air exiting the outlet vent  26  back into the inlet vent  14  (see arrow E in FIG.  3 ). 
     Another problem with the known funnel baffle  34  design is that it does not always adequately shield the rotor shaft bearing  46  (FIG. 3) from exposure to water and other contaminants. This can reduce the operating life of the bearing  46 . 
     Another problem with the known baffle design concerns its manner of assembly. A press machine is needed to mount the baffle  34  within the motor housing  12 . This adds undesirable labor costs to the overall assembly of the motor. 
     Accordingly, there is a need for a new electric motor baffle design which addresses the above noted problems and other problems. A feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within the motor housing, so that the baffle not only substantially prevents water and other contaminants which may enter an outlet vent in the motor housing from contacting certain internal components of the motor, it also allows air passing through the motor housing to exit the outlet vent without first having to radically change flow directions just prior to exiting the outlet vent. The streamlined air flow minimizes pressure loss in the hot exhaust air, so as to reduce the likelihood of the hot exhaust air from being recirculated back into an inlet vent in the motor housing. This greatly increases the cooling efficiency of the motor to better ensure that the motor will not overheat during operation, especially if the motor is operating under full load conditions or producing its maximum power. Another benefit of increasing the cooling efficiency of the motor may result in modifying material specifications for the motor, which may translate into reduced material costs, thereby increasing profitability of the overall motor design. 
     Another feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within a housing for the motor, such that the baffle is spaced a distance away from an inner surface of the housing to allow air entering an inlet vent in the motor housing to travel around the baffle, as opposed to through the baffle, and out an outlet vent without having to substantially change its direction of flow prior to exiting the outlet vent. 
     Another feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within a housing for the motor so as to protect a rotor shaft bearing from exposure to water and other contaminants which may enter the motor housing through an air outlet vent. According to one aspect of the invention, the motor includes an end frame which is mounted to the housing and which supports the bearing. The baffle abuts the end frame, and is preferably mounted directly to the end frame, to effectively shield the bearing from exposure to water and other contaminants. 
     Another feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within the housing without having to use a press machine, thereby reducing labor costs associated with assembling the motor. 
     In a preferred embodiment, the baffle according to the present invention includes a first ring shaped portion, a second portion forming a part of a frustum extending from the first portion, and a third portion forming a part of a cylinder extending from the second portion. Preferably, when the baffle is mounted to an end frame within a motor housing, the third portion axially overlaps a stator winding and rotor within the housing to substantially prevent water and other contaminants which may enter an outlet vent in the housing from contacting the stator winding and rotor. 
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view, partially in section, of an electric motor embodying the present invention. 
     FIG. 2 is an exploded perspective view illustrating a portion of the end frame, the rotor shaft bearing and the baffle of the electric motor shown in FIG.  1 . 
     FIG. 3 is a side elevational view, partially in section, of a prior known electric motor design. 
    
    
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrated in FIG. 1 is an electric motor  100  embodying the invention. It should be understood that the present invention is capable of use in other electric motors and the electric motor  100  is merely shown and described as an example of one such motor. 
     The motor  100  comprises a housing  114  having an axis  118 . The motor  100  also includes an end frame  122  mounted on one end  126  of the housing  114  and a second end frame  130  mounted on an opposite end  134  of the housing  114 . Although not clearly illustrated in FIG. 1, the end frames  122  and  130  may be separate from the housing  114 , or the housing  114  and the end frames  122  and  130  could be unitary. The motor  100  also comprises a stator core  138  supported by the housing  114  and fixed relative to the end frames  122  and  130 . The stator  138  includes a plurality of vent holes  142  which allow air to pass there through for cooling the motor, particularly the electrical windings  144  of the stator  138 . A bearing  146  is supported by the end frame  122 . Although not clearly shown in FIG. 1, a second bearing  150  is supported by the end frame  130 . A rotor shaft  154  is supported by the bearings  146  and  150  for rotation about the axis  118 . A rotor  158  is supported by the shaft  154  for rotation therewith relative to the stator  138 . 
     With continued reference to FIG. 1, the housing  114  includes air inlet vents  162  near end  134  and adjacent end frame  130 , and air outlet vents  166  near end  126  and adjacent end frame  122 . Although a plurality of vents  162  and  166  are shown, one or more vents may be provided. In general, motors adapted for outside use are typically mounted to a structure so as to lie in a horizontal plane, as representatively shown in FIG.  1 . For this reason and to best protect the internal components of the motor from exposure to water and other contaminants, the vents  162  and  166  are located in the bottom half of the housing  114 . A fan  170  is conventionally, operatively coupled to the shaft  154  and an inlet baffle  174  is mounted within the housing  114  adjacent the inlet vents  162 . FIG. 1 further illustrates baffle  178  which is supported relative to and within the housing  114  as will be further described below. 
     As can be appreciated, cooling air (representatively shown as arrows X in FIG. 1) enters the motor  100  through the inlet vents  162 . The cooling air is guided by the end frame  130  and inlet baffle  174  so as pass through the fan  170 . The cooling air then passes through the vent holes  142  in the stator  138  (representatively shown as arrow Y in FIG.  1 ). In the prior known motor  10  design of FIG. 3, the heated air would then pass through the funnel shaped baffle  34  and reach the adjacent end frame  38 . As explained, in the prior known motor  10  design, the hot air would then be forced to make a 180° turn between the funnel shaped baffle  34  and the adjacent end frame  38  prior to exiting the outlet vents  26  provided in the housing  12 . As explained, this abrupt change in the direction of air flow in the prior design produces a large pressure drop, such that the total amount of air flow is reduced and a significant portion of the hot exhaust air exiting the outlet vents  26  may be drawn or directed into the inlet vents  14 , thereby greatly reducing the cooling efficiency of the motor  10 . Unlike this prior known motor  10  design, after the cooling air passes through the vent holes  142  in the stator  138  of the motor  100  according to the present invention, the heated air passes around, as compared to through, the baffle  178  and is simply guided out of the outlet vents  166  (as representatively shown by arrow Z in FIG.  1 ). A feature of the present invention is that the air does not undergo a sudden change in flow direction prior to exiting through the outlet vents  166 . As a result, there is no significant pressure loss and the hot exhaust air flows away from, rather than back to, the intake vents  162 , thereby increasing the cooling efficiency of the motor. 
     FIG. 2 illustrates a preferred construction of the baffle  178 . The baffle  178  abuts the end frame  122 , and is preferably mounted directly to the end frame  122  with screws  182  (see also FIG.  1 ). A press machine is not needed to mount the baffle  178  within the housing  114 , as is the case with the prior known baffle  34  design shown in FIG.  3 . So mounted, the baffle  178  prevents rain and other external contaminants from reaching the rotor shaft bearing  146  (see also FIG.  1 ), thereby increasing the potential operating life and reliability of the bearing  146 . The baffle  178  includes a first ring shaped portion  186  which abuts end frame  122  (see also FIG.  1 ), a second portion  188  forming a part of a frustum and extending from the first portion  186 , and a third portion  190  forming a part of a cylinder and extending from the second portion  188 . As shown, the second portion  188  and the third portion  190  are not completely closed so as to define an open side  192  and a closed side  194 . Because the motor  100  is usually placed horizontally to the ground (see FIG.  1 ), the closed side  194  of the baffle  178  is positioned adjacent the outlet vents  166  to prevent water and other contaminants bouncing off of the ground or otherwise entering the vents  166  from reaching the vital components housed within the motor  100 . Since vents are typically not provided in the top half of the housing  114 , the baffle  178  does not need to be completely closed, hence the reason for the open side  192 . Even so, the baffle  178  may be closed if desired. 
     Referring again to FIG. 1, it can be observed that the baffle  178 , particularly the third portion  190 , is spaced a minimum distance  196  away from the inner surface  198  of the housing  114 . In a preferred arrangement, the spacing  196  is approximately the same size as the vent holes  142  in the stator  138 . As should be apparent, the spacing  196  between the baffle  178  and the housing  114  allows air entering the inlet vents  162  to pass through the housing  114  without being redirected around the baffle  178  before exiting the outlet vents  166 , thereby minimizing pressure loss in the flow of air before the flow of air reaches the outlet vents  166 . This generally linear flow of air through the motor  100  helps ensure that the hot exhaust air is directed away from the inlet vents  162  for the reasons previously explained. As can also be observed in FIG. 1, the baffle  178 , particularly the third portion  190 , axially overlaps at least a portion of the stator winding  144  and rotor  158  to prevent rain and other external contaminants which may enter the outlet vents  166  from contacting the stator winding and rotor  158 . 
     Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art. 
     Various features of the invention are set forth in the following claims.