Abstract:
A terminal lead insulator assembly for use in a wound field synchronous machine has a generally cylindrical skirt extending in a first direction from a radially larger face. The radially larger face is formed with a plurality of radially outwardly extending ears. The ears include central openings for receiving electrical connections. A rotor assembly, a wound field synchronous machine and a method of assembling such a rotor assembly, each of which include the terminal lead insulator assembly as mentioned above, are also disclosed and claimed.

Description:
BACKGROUND 
     This application relates to a terminal lead insulator assembly, which properly positions and protects terminal leads for a wound field synchronous machine. 
     Wound field synchronous machines are known and include a main field winding which is driven to rotate relative to a main stator. The main field winding is part of a rotor assembly that also carries exciter windings. A diode pack is typically provided to rectify AC power generated by the exciter. The rectified power takes the form of DC power and is delivered to the main field windings. 
     In the prior art, electrical connections must be made between the main windings and the diode pack, and between the exciter windings and the diode pack. 
     In some prior wound field synchronous machines, the electrical connections and wires extended through a shaft which rotates with the rotor and windings. More recently, in some wound field synchronous machines, these electrical connections have been positioned outside the shaft, and are generally unprotected within the overall rotor assembly. 
     SUMMARY 
     An electrical connection protector or terminal lead insulator assembly for use in a wound field synchronous machine has a generally cylindrical skirt extending in a first direction from a radially larger face. The radially larger face is formed with a plurality of radially outwardly extending ears. The ears include central openings for receiving electrical connections. A rotor assembly, a wound field synchronous machine and a method of assembling such a rotor assembly, each of which include the terminal lead insulator assembly as mentioned above, are also disclosed and claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows a wound field synchronous machine. 
         FIG. 2A  is a side view of a portion of the rotor of the wound field synchronous machine. 
         FIG. 2B  is a perspective end view of the rotor portion show in  FIG. 2A . 
         FIG. 3  shows a terminal lead insulator assembly. 
         FIG. 4  shows a first detail of the assembled rotor. 
         FIG. 5  shows another detail portion. 
         FIG. 6  shows yet another detail portion. 
         FIG. 7  shows geometric relationships with regard to the terminal lead insulator assembly. 
         FIG. 8  shows other geometric relationships. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a wound field synchronous machine  20  schematically. A source of drive  22 , such as a gas turbine engine and gear train drives a rotor assembly  24  of the wound field synchronous machine  20 . Exciter rotor  28  and main rotor  26 , are driven to rotate with a shaft  15 , and rotate adjacent exciter stator  30 , and main stator  29 . The exciter rotor  28  contains the exciter rotor windings. The main rotor  26  contains the main field windings. This structure may generally be as known, and operates to generate electricity which is transmitted from the main stator  29  to a user  130 . Additionally, this structure may operate to generate torque when a user  130  provides electricity to the main stator  29 . The exciter rotor winding  28  operates to convert power from the exciter stator to be sent to the main field winding  26  via the diode pack  101  (see  FIG. 4 ), again as known. 
       FIG. 2A  shows the rotor assembly  24  having the exciter rotor  28  winding  28  removed. In addition, a diode pack, which could not be seen in  FIG. 1 , is also removed. As can be appreciated from  FIGS. 2A ,  2 B and  3 , there are a plurality of ears  38  associated with a terminal lead insulator assembly  32  (also referred to as electrical connection protector  32 ). The ears  38  mechanically support and protect bus bar connections  40  and  42 , as well as receive a positioning pin  39 . Positioning pin  39  serves to index and position the terminal lead assembly protector  32 , and hence the connections bus bars  40  and  42 . To do so, an end  141  of the positioning pin  39  is received in the diode pack  101  (see  FIG. 4 ). This properly axially positions the terminal lead assembly protector  32 . 
     DC Connections  42  extend from the diode pack to bus bars  42 , and in turn to the main rotor winding  26 . There are two such connections. 
     AC connections  40  connect the diode assembly back to the exciter rotor. There are three such connections. 
     The bus bars  40  and  42  as illustrated in  FIGS. 2A and 2B  are shown with insulators  40 , wires, etc. As can be appreciated from  FIG. 2B , a skirt  34  that is generally cylindrical in shape extends toward the main rotor winding  26  from a forward face  41  of the protector  32 . This skirt provides dielectric protection between the DC connections  42  and the rotor shaft  15 . 
     As shown in  FIG. 3 , the terminal lead insulator assembly  32  includes the forward face  41 , and the skirt  34 . A plurality of ears  38 A,  38 B,  38 C,  38 D,  38 E and  38 F are formed in the face  41 . In addition, a groove  56  is formed at an outer periphery of the skirt  34 , and serves to provide clearance room for one of the bus bars  42 . As is clear from  FIG. 3  the ears  38 A- 38 F extend radially outwardly from the outer peripheral surface of the skirt  34 . 
     As shown in  FIG. 4 , the exciter rotor  28  surrounds the diode pack  101  (shown schematically). A nut  122  may be placed on the end  141  to secure the positioning pin assembly  39 . As can be appreciated from  FIG. 4 , the face  41  is also positioned radially inwardly of the exciter rotor  28 . 
       FIG. 5  shows a detail of one of the bus bar connections  40  extending through one of the ears  38 . Similarly,  FIG. 6  shows one of the bus bar connections  42 , extending also through one of the ears  38 . 
     In assembling the wound field synchronous machine  20 , the positioning pin assembly  39  is positioned to have the end  141  extend through the diode pack  101 , which has previously been positioned within the exciter rotor. The diode pack  101  is now in a fixed radial position, and thus the positioning pin is at a fixed radial position. When the positioning pin is moved into the ear  38  in the protector  32 , the protector  32  will be in a fixed circumferential location. The other electrical connections can now be made through the other ears  38  such that they are all properly positioned. 
       FIG. 7  geometrically shows relationships on the face  41 . As shown, radius R 0  extends to the inner periphery of the face  41 . R 0  will also be the inner periphery of the skirt  34 . A radius R 1  extends to one of the circumferential extending portions between the ears  38 A and  38 B. Another radius R 2  is formed between the ears  38 A and  38 F. R 2  is less than R 1 , and also less than R 3  between ear  38 F and  38 E, and R 4  between ears  38 C and  38 D. A radius R 5  extends to each of the center points of cylindrical connection holes extending through the ears  38 A,  38 B,  38 C,  38 D and  38 E. A radius R 6  extends to the outer periphery of the skirt  34  shown in phantom in this Figure. 
     In exemplary embodiments, the radius R 0  is between 1.04 and 1.55″ (26.4 and 39.4 mm), the radius R 1  is between 1.28 and 1.92″ (32.5 and 48.4 mm), the radius R 2  is between 1.20 and 1.80″ (30.5 and 45.7 mm), the radii R 3  and R 4  are equal to R 1 . The radius R 5  is between 1.30 and 1.96″ (33.0 and 49.8 mm), and the radius R 6  is between 1.13 and 1.169″ (28.7 and 29.7 mm). 
     Further, a length L 1  of skirt  34  as shown in  FIG. 8  is between 0.95 and 1.42″ (24.1 and 36.1 mm), whereas a length L 2  of the face  41  is between 0.59 and 0.89″ (15.0 and 22.6 mm). 
     In exemplary embodiments, a ratio of L 1  to L 2  is preferably between 1.55 and 1.75. A ratio of R 0  to R 6  is preferably between 0.85 and 0.95. A ratio of R 1  to R 2  is preferably between 1.05 and 1.15. Another ratio of R 0  to R 5  is between 0.75 and 0.85. Further, another ratio of R 0  to R 1  is between 0.75 and 0.85. 
     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.