Abstract:
A motor for use in a volatile environment includes a rotor exposed to the volatile environment, electronics for rotating the rotor, an impervious ceramic barrier separating the electronics and the rotor, and a flexible seal for preventing the volatile environment from contacting the electronics and for minimizing vibratory and twisting loads upon the barrier to minimize damage to the barrier.

Description:
[0001]    This invention was made with government support under Contract No. RH6-118203 awarded by NASA. The Government has certain rights in this invention. 
     
    
     BACKGROUND 
       [0002]    Some electric motors are “canned” or sealed using a metallic barrier to prevent an environment in which the motor is used from entering into the electrical portion of the motor. Such environments may include a fluid like a liquid or a gas. In running in volatile environments such as higher concentrations of oxygen, the volatile environment must be sealed from the electronics to prevent any sparks from interacting with the oxygen. 
       SUMMARY 
       [0003]    According to an exemplar, a motor for use in a volatile environment includes a rotor exposed to the volatile environment, electronics for rotating the rotor, an impervious ceramic barrier separating the electronics and the rotor, and a flexible seal for preventing the volatile environment from contacting the electronics and for minimizing vibratory and twisting loads upon the barrier to minimize damage to the barrier. 
         [0004]    A frangible barrier is disposed between a rotor and the electronics the rotor being disposed in a volatile atmosphere. The frangible barrier is supported by a set of O-rings that also act as seals to prevent the environment from reaching the motor electronics. 
         [0005]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a prior art embodiment of a canned electric motor. 
           [0007]      FIG. 2  shows an embodiment of an electric motor with a non-metallic barrier in a volatile environment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0008]    Referring to  FIG. 1 , a prior art example of a motor  10  used in an oxygen-rich environment  15  is shown. The motor  10  includes housing  20 , having a cylindrical body  25  with an end seal  30 . The housing  20  holds electronics  35  (such as controls and stator windings etc.) in which electricity is used. An electrically conductive canning material  40 , such a metal, is used to create a recess  70  in which a plurality of bearings  45  hold a rotor  50 . The canning material  40  is attached conventionally to the housing  20  at an open end  60  of the cylinder  25  and to an environment wall  65 . An O-ring  55  is disposed between the housing  20  and the environmental wall  65  to prevent the environment from leaking outside the motor  10 . The continuous canning material  40  seals the oxygen from reaching the electronics  35 . Unfortunately this metal canning reduces the motor efficiency as its speed is increased. For example, higher currents in the motor  10  can induce eddy currents in the canning material  40 . The eddy currents in the canning material  40  may interfere with magnetic flux between the rotor  50  and electronics  35 , resulting in drag forces and heating as electrical current is increased in the motor  10 . 
         [0009]    Referring now to  FIG. 2  a motor  100  is shown in a volatile environment  105 , such as a 100% oxygen environment of a space suit, though other volatile fluid mixtures in other locations are also contemplated herein as volatile environments. A housing  110  extends into the environment via a radially outboard portion  115 . The housing  110  also includes a cylindrical portion  120  closed off by end portion  125 . The interior  130  of the cylinder houses electronics  135  (like windings and controls) or the like. The housing  110  has a set of four radial grooves  140  that hold O-rings  145 , which may be made of silicone, or the like, as will be discussed herein below. 
         [0010]    The motor has a bearing set  150  disposed in races  155  at an inboard portion  160  and a radially outboard portion  165  to hold a rotor  170  that is disposed for rotation within the bearing sets  150 . A non-metallic barrier  175 , which may be frangible, thin, non-metallic, non-magnetic, ceramic material shaped like a cylinder is disposed within the O-rings  145 . Other shapes may be contemplated herein. The rotor  170  is configured for exposure to the volatile environment  105 , as a gap  180  exists between the rotor  170  and the non-metallic barrier  175 . 
         [0011]    By providing a very thin non-metallic bather  175  made of an impervious ceramic material, the efficiency of the motor  100  is greatly improved because interference with magnetic fluxes between the rotor  170  and electronics  135  is minimized The ceramic material for the non-metallic barrier  175  is used because non-metallic materials do not rust or bum in an oxygen rich or pure oxygen environment and are anti-magnetic. Though an embodiment uses stabilized zircona as the ceramic material, other morpheus and amorphous glasses and crystals such as sapphire, alumina, or the like may also be used. 
         [0012]    The non-metallic barrier  175  thickness may be approximately 0.025 inches (0.635 mm) thick and made of a ceramic material like a glass, as stated above, and such glass tends to be brittle. Motors for certain applications, like space exploration, may be subject to high vibrational and torquing environments. The O-rings  145  act as flexible seals to protect the ceramic material of the non-metallic barrier  175  from deflection within the motor  100  due to bending or twisting, or from vibration and shocks that may shatter a glass barrier in a rigidly mounted configuration. The compliance of the O-rings  145  gently constrains the non-metallic barrier  175  and isolates it from the harsh external motor environment. The combination of the O-rings  145  and the non-metallic barrier  175  isolate the electronics  135  from the volatile environment  105  to which the rotor  170  may be exposed. 
         [0013]    While glass is contemplated herein other frangible materials that do not interfere with the magnetic flux between the rotor and the stator of a motor are here also contemplated. 
         [0014]    Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
         [0015]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.