Abstract:
A power distribution contactor mount, and a power distribution system incorporating the same, include a plurality of electrically and thermally conductive contactor posts operable to connect a contactor lead to a bus bar, a mounting panel face, wherein each of the contactor posts is received in the mounting panel face and extends through the mounting panel face, and a first heat dissipation component mounted on the mounting panel face and thermally connected to each of the contactor posts. The thermal connection is via a thermally conductive and electrically insulative polymer insert, and each of the posts protrudes through the first heat dissipation component.

Description:
TECHNICAL FIELD 
     The present disclosure is directed toward power distribution contactors, and more particularly to power distribution contactors including thermal management features. 
     BACKGROUND OF THE INVENTION 
     Commercial aircraft include onboard power systems typically including a power generation system and a power distribution system. The power systems are used to generate and distribute power during operation of the aircraft, and the power is used to power onboard electronic systems. As part of the power distribution system, electric contactors control power flow over a series of power distribution buses. The contactors control the flow of current in the bus bars, and mechanically switch current on or off as needed by the power systems. 
     Due to the switching within the contactor modules, the contactors generate heat during operation of the power distribution system. Heat from the contactor leads is conducted to external power distribution bus bars and from the external power distribution bus bars into the ambient atmosphere. To accommodate this cooling feature, the external power distribution bus bars are sized large enough that the heat can be properly dissipated. An additional step utilized to facilitate the additional heat dissipation requirements is the utilization of copper, in place of the lighter weight aluminum, as the primary metal of the bus bars. Utilization of a heavier material increases the weight of the bus bar and the overall power distribution assembly. 
     SUMMARY OF THE INVENTION 
     Disclosed is a power distribution system including a bus bar contactor having a contactor circuit with a plurality of contactor leads, a plurality of electrically and thermally conductive contactor posts operable to connect the contactor leads to a bus bar, a mounting panel face, wherein each of the contactor posts is received in the mounting panel face and extends through the mounting panel face, a first heat dissipation component thermally connected to each of the contactor posts, wherein the thermal connection is via a thermally conductive and electrically insulative polymer insert, and wherein each of the posts protrudes through the first heat sink. 
     Also disclosed is a power distribution contactor mount including a plurality of electrically and thermally conductive contactor posts operable to connect contactor leads to a bus bar, a mounting panel face, wherein each of the contactor posts is received in the mounting panel face and extends through the mounting panel face, a first heat dissipation component mounted on the mounting panel face and thermally connected to each of the contactor posts, wherein the thermal connection is via a thermally conductive and electrically insulative polymer insert, and wherein each of the posts protrudes through said first heat dissipation component. 
     Also disclosed is a method for cooling a power distribution contactor including the steps of thermally connecting a power distribution contactor to a heat dissipation feature using a thermally conductive polymer insert and dissipating heat using the heat dissipation feature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates an aircraft power distribution system. 
         FIG. 2  schematically illustrates a bus bar contactor module installed in a power distribution panel. 
         FIG. 3A  schematically illustrates a front view of a three phase contactor module mount in a power distribution panel. 
         FIG. 3B  schematically illustrates a side view of the three phase contactor module mount of  FIG. 3A . 
         FIG. 4  schematically illustrates a second alternate example bus bar contactor module installed in a power distribution pane. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates an aircraft  10 . During operation of the aircraft  10 , electric power is generated in a generator  20  using mechanical rotation of a jet engine  22 . The electric power generated in the generator  20  is passed to a power distribution system  30  that uses contactors  32  to control power distribution over power conduits  40  and thereby distribute electric power to multiple on board electric systems  50  as needed. 
     The contactors  32  are mounted in a power distribution panel and operate to control current through the power distribution system  30  by switching a mechanical relay, or an electrical equivalent of a mechanical relay. As a result of this functionality, each of the contactor modules  32  generates heat. In order to prevent an undesirable buildup of heat within the power distribution system  30 , the heat is shunted to an attached bus bar being controlled by the contactor modules  32  and the heat is dissipated into the ambient air from the bus bar. 
       FIG. 2  illustrates an example power bus contactor module  100  installed on a power distribution panel  120 . The power bus contactor module  100  includes electric leads  112  that are connected to a power distribution bus bar  110  using contactor posts  114 . The contactor posts  114  are maintained in position using a post support  116 . The contactor module  100  controls power flow across the power distribution bus bar  110  utilizing standard internal switching relays that connect the bus bars  110  when power is desired to flow, and disconnect the bus bars  110  when no power flow is desired. 
     The contactor module  100  is mounted on a non-conductive power distribution panel  120 . In a typical arrangement, the power distribution panel  120  mounts multiple power distribution components in a centralized location. 
     Also mounted on the power distribution panel  120  is a heat sink  130 . The heat sink  130  is connected to the power distribution panel  120  via a heat sink base  132 . The heat sink includes multiple cooling fins  134  extending away from the heat sink base  132  and the power distribution panel  120 . As the non-conductive power distribution panel  120  is not thermally conductive, and the utilization of an electrically conductive connection to the heat sink  130  would cause the contactor module  100  to be shorted across the heat sink  130 , a thermally conductive polymer insert  140  connects the contactor posts  114  to the heat sink  130 . Similarly, the post support  116  abuts only the thermally conductive polymer insert  140  in order to prevent short circuiting the contactor module  100 . For the purposes of this application, a thermally conductive polymer is any polymer that is both thermally conductive and electrically insulative, such as a COOLPOLY plastic. 
     The action of switching power, as well as the flow of power through the contactor module  100 , generates large amounts of heat that builds up to undesirable levels if the heat is not dissipated into the surrounding atmosphere. In the illustrated example of  FIG. 2 , heat generated in the contactor module  100  flows through the electric leads  112  into the contactor posts  114 . From the contactor posts, the heat flows through the thermally conductive inserts  140  into the base  132  of the heat sink  130  and into the cooling fins  134 . The heat is then dissipated into the ambient atmosphere from the heat sink base  132  and the cooling fins  134 . A minimal amount of heat is similarly dissipated in the atmosphere from the leads  112  and the contactor posts  114 . The cooling fins  134  increase the surface area of the heat sink  130 , thereby increasing the amount of heat that can be dissipated in the ambient air in a smaller volume. 
       FIGS. 3A and 3B  schematically illustrated a top view ( FIG. 3A ) and a side view ( FIG. 3B ) of a three phase contactor module mount  200  in a power distribution panel. Three pairs of contactor posts  220  (one pair per phase) protrude through a heat sink base  210  from a power distribution bus  250 . The contactor posts  220  are electrically isolated from the heat sink base  210  via a thermally conductive insert  230 . The heat sink includes multiple cooling fins  240  that operate dissipate heat into the surrounding atmosphere as described above with regards to  FIG. 1 . 
       FIG. 4  illustrates an alternate example contactor module  300  and mounting arrangement. As with the example of  FIG. 1 , the contactor module includes electric leads  312  connecting the contactor module to contactor posts  314 . The contactor posts  314  connect the electric leads  312  to a power distribution bus bar  310 , thereby allowing the contactor module  300  to control the flow of current through the power distribution bus bar  310 . 
     In place of the non-conductive power distribution panel of the example of  FIG. 1 , the power distribution panel of  FIG. 4  is a thermal ground plane  320 . The thermal ground plane  320  includes a hollow core  324  that is partially filled with a coolant and includes multiple heat fins  322 . In some examples, the multiple heat fins are connected to the thermal ground plane via a perforated heat sink base  317 . A surface  316  of the thermal ground plane  320  can be referred to as a mounting panel face, the perforated heat sink base  317  contacting the mounting face panel  316 . In order to accommodate the thermal ground plane  320 , an insert  330  constructed of a thermally conductive polymer electrically isolates the contactor posts  314  from the thermal ground plane  320 . The portions of the thermal ground plane  320  immediately contacting the thermally conductive polymer insert  330  are evaporating surfaces  326 , and the surfaces immediately contacting the cooling fins  322  are condensing surfaces  328 . 
     During operation of the contactor module  300 , the generated heat conducts out of the contactor module  300  into the contactor posts  314  by way of the leads  312 . From the leads, the heat conducts into the thermal ground plane  320  through the thermally conductive polymer insert  330 . The heat enters the thermal ground plane  320  at the evaporating surface  326 , which is immediately adjacent the contactor  314 . As the evaporating surface heats up, the coolant within the thermal ground plane  320  converts from a liquid state into a gas state (evaporates). The evaporated coolant flows away from the evaporating surface  326  and contacts the cooler condensing surface  328  that is thermally removed from the evaporating surface  326 . The condensing surface draws heat out of the evaporated coolant and into the cooling fins  322 . This removal of heat from the coolant causes the coolant to return to a liquid form (condense). 
     The condensed coolant contacts a wicking surface  329 . The wicking surface  329  includes a wicking structure that draws the liquid coolant back towards the evaporating surface  326 . Once the liquid coolant is returned to the evaporating surface, the liquid coolant evaporates again, and the cooling cycle is repeated. In this way, the heat is dissipated using both a coolant state change and cooling fin  322  dissipation into the ambient atmosphere. 
     In another alternate example, the contactor module mount is configured as in  FIG. 4  with the addition of a heat sink base providing an efficient thermal path directly from the contactor posts  314  to the cooling fins  322 , thereby combining the contactor module mount of  FIG. 2  and the contactor module mount of  FIG. 4 . This combination recognizes benefits of both configurations with a minimal reduction in the effectiveness of each of the ambient air dissipation and thermal ground plane cooling methods. 
     Although a 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.