Abstract:
A rectifier assembly includes first and second housings surrounding a pair of electrical rings. Each of the electrical rings communicates with a pin. Bolts secure a spring to hold diodes against an inner wall of the electrical rings. The first housing includes openings opposed to the bolts to allow access to the bolts for tightening the bolts to hold the spring, and bias the diodes against the inner periphery of the electrical rings. A rotor balance assembly, a generator, and a method of assembling a rectifier assembly are also disclosed and claimed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This application relates to a rectifier assembly for a generator, wherein the rectifier assembly is easily assembled. 
         [0002]    Generators are known, and typically include a generator rotor having main windings that are driven to rotate by a source of rotation. As an example, a generator may be driven to rotate by the output of a gas turbine engine. In typical generator operation, a flow of current is supplied to the main windings. The main windings rotate adjacent to a stator, and electricity is generated, and used for various purposes. 
         [0003]    In one known type of generator, a so-called exciter rotor rotates adjacent to a stator, and generates current to be delivered to the main windings as a current to facilitate the main generation of electricity. 
         [0004]    The current generated by the exciter rotor is typically an AC current and a rectifier is utilized to transform that AC current into a DC current for use by the main windings. In the past, the rectifiers have been somewhat difficult to assemble. 
       SUMMARY OF THE INVENTION 
       [0005]    A rectifier assembly includes first and second housings surrounding a pair of electrical rings. Each of the electrical rings communicates with a pin. Bolts secure a spring to hold diodes against an inner wall of the electrical rings. The first housing includes openings opposed to the bolts to allow access for tightening the bolts to hold the spring, and bias the diodes against the inner periphery of the electrical rings. 
         [0006]    A rotor balance assembly includes a main winding on a rotor shaft and an exciter winding on the rotor shaft. A rectifier assembly is received in a bore in the shaft, and includes first and second housings surrounding a pair of electrical rings. Each of the electrical rings communicates with a pin. Bolts secure a spring to hold diodes against an inner wall of the electrical rings. The first housing includes openings opposed to the bolts to allow access for tightening the bolts to hold the spring, and bias the diodes against the inner periphery of the electrical rings. 
         [0007]    A generator includes a main stator and a main winding, an exciter rotor and an exciter winding. The main exciter windings rotate with a shaft. The exciter rotor communicates with a rectifier assembly. The rectifier assembly communicates with the main winding and is received in a bore in the shaft. The rectifier assembly includes first and second housings surrounding a pair of electrical rings. Each of the electrical rings communicates with a pin, and bolts to secure a spring to hold diodes against an inner wall of the electrical rings. The first housing includes openings opposed to the bolts to allow access for tightening the bolts to hold the spring, and bias the diodes against the inner periphery of the electrical rings. 
         [0008]    A method of assembling a rectifier assembly includes the steps of assembling a plurality of electrical rings and insulators within a housing, and inserting a drive tool through an opening in an outer wall of the housing, and into bolts associated with springs, tightening the bolts by the tool to hold the spring to bias diodes against inner peripheral walls of the electrical rings. 
         [0009]    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 
         [0010]      FIG. 1  is a cross-sectional view through a generator. 
           [0011]      FIG. 2A  is a first view showing the main components of the rectifier assembly. 
           [0012]      FIG. 2B  shows the rectifier assembly. 
           [0013]      FIG. 3  is an exploded view of the rectifier assembly. 
           [0014]      FIG. 4  is a cross-sectional view through the rectifier assembly. 
           [0015]      FIG. 5  shows the electrical portions of the rectifier assembly. 
           [0016]      FIG. 6  is a perspective view of a portion of the rectifier assembly. 
           [0017]      FIG. 7A  is a cross-sectional view through a first housing portion. 
           [0018]      FIG. 7B  is an outer view of the first housing portion. 
           [0019]      FIG. 8A  is an end view of the second housing portion. 
           [0020]      FIG. 8B  is a cross-sectional view through the second housing portion. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]      FIG. 1  shows a generator  20  incorporating a main stator  22  adjacent to main windings  24 . A generator shaft  26  is driven to rotate by a source of rotation, which may be a gas turbine engine. An exciter rotor  28  is mounted on the shaft, and rotates adjacent to an exciter stator  29 . As known, the rotation of the exciter rotor  28  generates an AC current, which is delivered to the main winding  24  through DC connector pins  50  and  151 . Connections are shown schematically from the pins  50  and  151  going to the main windings  24 . This portion of the invention is as known in the art. A wire  32  passes through slots  34  in the shaft  26  and is connected to electrical terminals  66 . The detail of the generator shaft  26 , and the slots  34 , are better disclosed in a co-pending U.S. patent application Ser. No. ______, filed on even date herewith and entitled “Generator Rotor with Improved Hollow Shaft.” 
         [0022]    A rectifier assembly  38  is shown within an inner bore in the generator shaft  26 . 
         [0023]    As shown in  FIG. 2A , the rectifier assembly  38  incorporates an end housing  60 , an insulator  68 , a first electrical ring  70 , a second insulator  52 , a second electrical ring  56 , and another insulator  52 . As can be seen, the pins  50  and  151  extend beyond insulator  52 . 
         [0024]    This assembly is shown in  FIG. 2A  without the housing portion  62 .  FIG. 2B  shows the housing portion  62  assembled to the housing portion  60 . In addition, an oil supply tube  36  is shown in  FIG. 2B  extending outwardly of the assembly  38 . It should be understood that the oil supply tube  36  need not be part of the rectifier assembly  38 , and that further, if it is inserted into the assembly, it is inserted after the various screws are tightened, as will be discussed below. Holes  64  and  65  extend through the first housing  62  to allow access to internal screws or bolts. 
         [0025]      FIG. 3  is an exploded view of the assembly  38 , and shows the oil supply tube  36 . The housing  60  is shown adjacent to the terminals  66 . An insulator  68  includes slots  69  that extend for a generally great circumferential distance and each receive a terminal  66 , and smaller slots  71  which provide access to tighten a bolt that is to be received in the terminal  66 . The insulator  68  is preferably formed of a plastic. Electrical ring  70  is formed of copper, and includes diodes  75 . Spring strips  74  carry three bolts  72 , one to be associated with the terminal  66 , and the other two to be associated with nuts  54  formed in two spaced insulators  52 . Ledges  79  on the springs  74  extend away from a face  81  of the springs that carries the bolts  72 . Ledges  79  abut and hold diodes  75  against an inner wall of the electrical rings  70  and  56 . As shown, the insulators  52  include holes  53  to allow access to an opposed bolt and slots  73  to receive and hold nuts  54 . 
         [0026]    As shown in  FIG. 4 , the holes  64  are positioned to be opposite of bolts  72  in each of the insulators  52 . Similarly, slots  65  at an axial end of the housing  62  allows access to the bolt  72  received in terminals  66 . As appreciated from this Figure, the diodes  75  are biased by the ledges  79  against an inner surface of the electrical connection members  70  and  56 . 
         [0027]    When assembling the diode assembly  38 , one initially assembles the housing components onto the second housing  60 . The first housing  62  is then brought over the assembly. At that point, the bolts  72  are tightened by moving a tightening tool  600  through the holes  64 ,  65 ,  53 , and  71 . As can be seen, the holes are opposed to the location of the bolts. While the holes can be spaced 180° from the bolts, all that is intended by the term “opposed” is that the holes allow access to the bolts for tightening. After this assembly, the oil tube may then be moved into the housing. As shown on the right hand side, a tool  600  extends through the holes  64  and  53  and is tightening the bolts  72 . It should be understood there are three circumferentially spaced sets of the bolts  72  at each of the three axial locations. 
         [0028]    By utilizing the two housing portions, and by providing the bolt access holes, the present invention simplifies the assembly when compared to the prior art. 
         [0029]      FIG. 5  shows the electrical components of the overall rectifier assembly  38 . As can be appreciated, the pins  50  and  151  each extend to a slot  201  in their respective electrical rings  70  and  56 . The pins provide a positive and negative connection. 
         [0030]      FIG. 6  shows the electrical ring  70 , but the illustration would also apply to the ring  56 . As shown, flat surfaces  203  receive a diode, and curved portions  205  are formed circumferentially between the flats  203 . An ear  210  includes an opening  201  to receive a pin  50 , or  151 . 
         [0031]      FIG. 7A  shows the first housing element  62 . As shown in this cross-sectional view, a slot  303  provides room for ear  210 . The sot  301  receives the connection pins  151 . It should be understood that spaced from this view would be a longer slot  301  to be associated with the longer connection pin  50 . Grooves  111  extend circumferentially about the inner periphery to circulate oil. 
         [0032]    As shown in  FIG. 7B , holes  115  on an outer periphery of the first housing member  62  communicate grooves  111  with outer peripheral tube slots  113 . 
         [0033]      FIG. 8A  shows the second housing member  60  having openings  163  to receive the terminals  66 . As shown in  FIG. 8B , holes  161  in this housing allow access to the screw threads for tightening. A central tri-lobular hole  200  receives a tri-lobular head of the oil supply tube, to properly position the oil supply tube. Of course, other non-cylindrical shapes may be utilized to properly position the oil supply tube. A ledge  201 , as shown in  FIG. 8B , provides a stop for the head on the oil supply tube. In this way, the oil supply tube is properly positioned relative to the remainder of the assembly such that oil holes  19  in the oil supply tube are aligned with the diodes  75  (see  FIG. 4 ). 
         [0034]    Although embodiments of this invention have 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.