Abstract:
A slip ring has a rotating portion configured to take in signals from rotating electric transmission elements, and communicate those signals into a static portion. The rotating portion has a plurality of resistors which rotate. The resistors have an outer peripheral surface, and a containment ring surrounding the outer peripheral surface of the plurality of resistors. A method of testing a rotating component is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This application relates to a containment band for holding a plurality of resistors which are part of a slip ring in a testing system. 
         [0002]    Many components must be tested after manufacture. Some components are subject to rotation at speeds that will approximate their rotational speed and use. 
         [0003]    Sensors, such as strain gauges, may be mounted to sense stresses and strains in the component, such as during high speed rotation. These signals must be sent to a controller, which may be static. 
         [0004]    A so-called slip ring is often utilized to communicate rotating electric transmission systems to a static control. One known type of slip ring includes a resistor bridge associated with a rotating part of the slip ring. This resistor bridge will rotate at high speed along with the rotating component. 
       SUMMARY OF THE INVENTION 
       [0005]    A slip ring has a rotating portion configured to take in signals from rotating electric transmission elements, and communicate those signals into a static portion. The rotating portion has a plurality of resistors which rotate. The resistors have an outer peripheral surface, and a containment ring surrounding the outer peripheral surface of the plurality of resistors. A method of testing a rotating component is also disclosed. 
         [0006]    These and other features may be best understood from the following drawings and specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1A  is a schematic view of a testing system. 
           [0008]      FIG. 1B  is a schematic view of a ram air turbine testing system. 
           [0009]      FIG. 2  shows a portion of a slip ring. 
           [0010]      FIG. 3  is a side view of the  FIG. 2  portion. 
           [0011]      FIG. 4  is a side view. 
           [0012]      FIG. 5A  shows a second embodiment. 
           [0013]      FIG. 5B  is a detail of the second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1A  shows a testing system  20 . A component  22  to be tested is mounted within a driving member  24 . Driving member  24  is driven to rotate by a motor  26  and, in turn, transmits rotation to the component  22 . The component  22  may be a component that will expect to see high speed rotation during use. 
         [0015]    Strain gauges  27  are associated with the component  22  and communicate to a slip ring  28 . As known, a slip ring has a rotating portion  29  that takes signals in from rotating electric transmission members and communicates them to a static portion  30 . The signals then pass to a control  32   
         [0016]    System  20  may operate by having motor  26  drive member  24  to drive the component  22 . 
         [0017]      FIG. 1B  shows another test system  120 . Test system  120  may be utilized if the component  122  to be tested is a ram air turbine. As known, a ram air turbine has a propeller  123  that may be deployed from an aircraft. The propeller  123  is driven by air as the aircraft moves through the air and communicates to a generator  124  in a housing  132  to generate electricity. Such systems are known, and utilized to provide emergency electrical power for an aircraft. 
         [0018]    As shown, the test system  120  may include a wind tunnel  118  for driving air towards the propeller  123 . Gauges  127  are mounted on the propeller, and communicate to a rotating portion  129  of a slip ring, which in turn communicates to a static portion  130  mounted on the housing  132  of the ram air turbine. Static portion  130  communicates signals to a control  131 . 
         [0019]    The system, with a wind tunnel, could also be utilized to test the ram air turbine  122  while it is actually mounted on an aircraft. 
         [0020]    This rotation may be at very high speeds, for example on the order of 4500 rpm. Of course, other speeds would come within the scope of this disclosure. During this rotation, the gauges  27  monitor the stresses and strains within the component  22  and communicate signals through slip ring  30  and to control  32 . 
         [0021]    As shown in  FIG. 2 , rotating portion  29  (rotating portion  129  would be constructed in a similar manner) has a resistor bridge including a plurality of rectangular resistors  38  communicating through members  34  and wires  36 . Wires  34  extend from the resistors  38  to a turret  37 . Other wires  36  communicate with the strain gauges. A brush  39  is shown in phantom, and would sit axially spaced outwardly of the plane of  FIG. 2 , and be a part of the slip ring static portion  30 . As the turrets  37 , wires  34  and  36 , and resistors  38  all rotate, they move along the brushes  39  which communicate the electrical signals through brushes  39  and to control  32 . This structure will rotate at high speed. Thus, the resistors  38  will see centrifugal forces urging them outwardly. 
         [0022]    A containment ring or band  40  is formed about the resistors  38  to contain them during high speed rotation. 
         [0023]    As shown in  FIG. 3 , containment ring  40  need not cover the entire axial length of the resistors  38 . 
         [0024]      FIG. 4  shows details of the containment ring  40  including a plurality of pins  42  for attachment to a portion  43  of the slip ring  30 . Brush  39  is shown schematically. In the disclosed embodiment, there are three pins  42 . Each may have a diameter of 0.050 inch (0.127 centimeter) and may extend for an axial length of 0.25 inch (0.635 centimeter). The pins are equally spaced by 120 degrees. An epoxy may also be utilized to assist in securing the band  40  to the portion  43 . 
         [0025]    A second embodiment 60 is illustrated in  FIG. 5A . Second embodiment 60 is a ring with a generally cylindrical outer peripheral surface  62 , but having a plurality of flats  64  on an inner peripheral surface. As shown, part-circular portions  65  separate the flats  64 . As mentioned, resistors  38  have a flat outer surface, and the flats  64  formed on the inner periphery of containment ring  60  may serve to better position the resistors  38 . 
         [0026]    As shown in  FIG. 5B , there is a distance d 1  over which the part-circular portions  65  extend between edges of adjacent flats  64 . In one embodiment, the distance d 1  was 0.027 inch (0.068 centimeter). The resistors extend over a second distance d 2 . In one embodiment, the distance d 2  was 0.300 inch (0.762 centimeter). 
         [0027]    In embodiments, the resistors may bonded to the band  40  using a potting compound, such as Dolph Motor Potting Compound. 
         [0028]    Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.