Patent Publication Number: US-6210036-B1

Title: Connector thermal sensor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Provisional Patent Application Ser. No. 60/025562, filed Sep. 06, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to temperature management, specifically to limiting the temperature rise within an aircraft ground power connector. 
     Presently, a parked aircraft receives external electrical energy via a ground power cable provided with an electrical plug. (By “ground” power cable is meant a cable connected to power on the ground at an airport rather than power provided by an aircraft visiting such airport.) The ground power plug is installed to a mating receptacle complimentary power connector  53  on the aircraft, thus completing the connection from a ground power source to the aircraft. 
     Conditions exist wherein the electrical power contacts, either on the ground power plug or on the aircraft receptacle have become unfit for service because of wear or physical damage. 
     Often, the wear or damage goes unnoticed and an unfit connector is put into service. The damage manifests itself in the form of excessive electrical contact resistance with attendant energy loss in the form of heat. Power levels for aircraft electrical service are high, thus poor connections are able to produce a large amount of destructive heat in a brief period. The heat produced can and does cause costly damage to the aircraft as well as to ground power plug assembly. 
     At present, no known attempt has been made to automatically prevent the application of an unserviceable connector, either on the aircraft or ground equipment. Manual inspection tools are available, but are employed only if connector damage is noticed or during periodic inspection. 
     This invention automatically causes the removal of electrical energy from a connector that is experiencing excessive temperature rise, thus minimizing the risk of thermal damage to the aircraft or ground equipment. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a connector thermal sensor comprises an electrical thermal sensing device incorporated into the body of an electrical connector assembly. The connector thermal sensor is located within the electrical connector body such that the sensor is thermally coupled to the electrical power contacts. Thus, the connector thermal sensor will provide an indication of the heat or energy loss produced by the electrical power contacts. The indication provided by the connector thermal sensor is communicated to remote equipment responsible for controlling the energy presented to the electrical power contacts. The connector thermal sensor permits energy passing through the power contacts to be managed, and in so doing minimizes the risk of thermal damage caused by excessive energy loss within a connector assembly. 
     Accordingly, several objects and advantages of our connector plug thermal sensor are: 
     (a) to minimize the risk of aircraft damage caused by a poor quality connection to a ground power source; 
     (b) to reduce the risk of damage to ground power components; 
     (c) to reduce aircraft departure delays caused by aircraft ground power difficulties; 
     (d) to reduce the usage of power sources aboard the aircraft, thus reducing both air and noise pollution; 
     (e) to reduce the amount of fuel consumed by aircraft onboard power sources while the aircraft is parked; 
     (f) to provide a safety device that functions without modification of an existing system; 
     (g) to promote a safe operating environment by providing for cost effective, automatic control of a known hazard. 
     Still further objects and advantages will become apparent from a consideration of the ensuing description and accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawing figures classify aircraft-ground-power electrical plugs by number, for instance # 1  PLUG, for reference on these drawings only. 
     FIG. 1 shows a face view of conventional, # 1 , aircraft ground-power plug. 
     FIG. 1A shows a partial section view, with three power contacts, of the left side of # 1  plug. 
     FIG. 1B shows a partial section view, with one power contact and two control contacts, of the right side of # 1  plug. 
     FIG. 1C shows an electrical schematic of # 1  plug. 
     FIG. 1D shows a right side view of # 1  plug. 
     FIG. 1E shows a legend defining the schematic symbols in FIG.  1 C. 
     FIG. 2 shows a face view of single sensor, modified, # 2  aircraft ground-power plug. 
     FIG. 2A shows a partial section view, with three power contacts, of the left side of # 2  plug. 
     FIG. 2B shows a partial section view of the right side of # 2  plug. 
     FIG. 2C shows an electrical schematic of # 2  plug. 
     FIG. 2D shows a right side view of # 2  plug. 
     FIG. 2E shows a legend defining the schematic symbols in FIGS. 2C,  3 C and  4 B (plugs # 2 , # 3 , &amp;# 4 ). 
     FIG. 3 shows a face view of dual sensor, modified, # 3  aircraft ground-power plug,. 
     FIG. 3A shows a partial section view of the left side of # 3  plug. 
     FIG. 3B shows a partial section view of the right side of # 3  plug. 
     FIG. 3C shows an electrical schematic of # 3  plug. 
     FIG. 3D shows a right side view of # 3  plug. 
     FIG. 4 shows a face view of # 4  plug. 
     FIG. 4A shows a partial section view of the right side of # 4  plug. 
     FIG. 4B shows an electrical schematic of # 4  plug. 
     FIG. 4C shows a right side view of # 4  plug. 
     FIG. 5 shows a face view of single sensor, modified, # 5  aircraft ground-power plug replaceable nose section. 
     FIG. 5A shows a partial section view of the right side of # 5  replaceable plug nose. 
     FIG. 5B shows an electrical schematic of # 5  replaceable plug nose. 
     FIG. 5C shows a rear view of # 5  replaceable plug nose. 
     FIG. 5D shows a partial section view of the left side of # 5  replaceable plug nose. 
     FIG. 5E shows a legend defining the schematic symbols in FIGS. 5B &amp; 6B. 
     FIG. 6 shows a face view of a dual sensor, modified, # 6  aircraft ground-power plug replaceable nose section. 
     FIG. 6A shows a partial section view of the right side of # 6  replaceable plug nose. 
     FIG. 6B shows an electrical schematic of # 6  replaceable plug nose. 
     FIG. 6C shows a rear view of # 6  replaceable plug nose. 
     FIG. 6D shows a partial section view of the left side of # 6  replaceable plug nose. 
    
    
     DETAILED OF THE INVENTION 
     FIGS. 1-1E show “# 1  plug”, a conventional, un-modified, three phase, 400 Hertz, aircraft ground power plug connector  20  shaped to interact with a complementary power socket on an aircraft. A power contact socket  26  (FIGS. 1,  1 A &amp;  1 B) is provided for each of three voltage phases and neutral. A power conductor  28  or, in other words, an electric power lead is connected to each power contact socket  26 . A control contact socket  22  (FIGS. 1,  1 A &amp;  1 B) is provided for each of two control circuits. A control conductor  24  or, in other words, a control lead is connected to each control contact socket  22 . 
     Plug  20  provides a direct through path for power and control conductors. 
     A power cable  46  is attached to the end of plug  20 . Power cable  46  houses power conductors  28  and control conductors  24 . Power cable  46  connects power contact sockets  26  to a power source. Power cable  46  also usually, connects control contact sockets  22  to a power source control circuit. 
     Description—Preferred Embodiment—FIGS.  2 - 2 E 
     FIG. 2 shows the face of a modified, aircraft ground power plug  40 . Shown are a thermal sensor cavity  34 , a cavity seal  38 , power contact sockets  26 , and control contact sockets  22 . FIG. 2A shows a partial left section of plug  40  with power contact sockets  26  and power conductors  28 . FIG. 2B shows a partial right section of plug  40 , with thermal sensor  30 , thermal sensor cavity  34 , and cavity seal  38 . 
     Thermal sensor  30  (FIG. 2B) is positioned interstitially amongst three power socket contacts  26  and one control contact socket  22 . The three power socket contacts  26  are associated with voltage phases A, B, and C. 
     Thermal sensor  30  (FIGS. 2B &amp; 2C) is series connected into at least one control conductor  24 , via a thermal sensor wire  32 . 
     In most instances, thermal sensor  30  will be a normally closed, contact type switch. Other types of sensing devices may be employed. 
     Thermal sensor  30  (FIG. 2B) is connected within thermal sensor cavity  34 . As shown, cavity seal  38  (FIG. 2B) closes an open end of cavity  34  to prevent environmental intrusion into thermal sensor cavity  34 . Description—Alternate Embodiments—FIGS. 3-6D 
     Thermal sensor  30  (FIGS. 3, &amp;  3 B) is provided in two places in an alternate embodiment of our “Connector Thermal Sensor”. This alternate embodiment places an additional thermal sensor  30 , thermal sensor cavity  34 , and cavity seal  38  near power contact socket  26  [N]. 
     Thermal sensors  30  (FIGS. 3B &amp; 3C) are shown electrically connected in series. 
     Figure descriptions for # 2  plug (FIGS. 2-2E) apply to # 3  plug (FIGS.  3 - 3 D), with an additional thermal sensor  30 , thermal sensor cavity  34 , and cavity seal  38  in the # 3  plug. 
     FIGS. 4-4C show # 4  plug, an alternate embodiment of our “Connector Thermal Sensor”. This plug is equipped with one control contact socket  22 , two power contact sockets  26 , and one thermal sensor  30  (FIGS.  4  &amp;  4 A). 
     FIG. 4B shows an electrical schematic of # 4  plug. FIG. 4C shows a right side view of # 4  plug. 
     Figure descriptions for # 2  plug (FIGS. 2-2E) apply to # 4  plug (FIGS.  4 - 4 C), with one fewer control contact socket  22  and two fewer power contact sockets  26  in # 4  plug. 
     FIGS. 5-5E show # 5  plug, an alternate embodiment of our “Connector Thermal Sensor”. This plug is a replaceable nose or contact section. The # 5  plug is fitted to the contact end of certain aircraft ground power plugs, similar to # 1  plug (FIGS.  1 - 1 E), to enhance repairability. 
     The rear side of # 5  plug (FIG. 5C) is equipped with a projecting control contact pin  52  on each control conductor  24  (FIG. 5A) and a projecting power contact pin  36  on each power conductor  28  (FIGS.  5 A &amp;  5 D). As illustrated this results in the pins being electrically connected in series within the body of the plug, with their corresponding sockets. 
     Thermal sensor cavity  34  and cavity seal  38  (FIGS. 5,  5 A &amp;  5 C) may be provided on the rear surface, front surface or both. surfaces 
     Figure descriptions for # 2  plug (FIGS. 2-2E) apply to # 5  plug (FIGS.  5 - 5 E), with the inclusion of control contact pins  52 , power contact pins  36  (FIGS.  5 A &amp;  5 D), and absence of power cable  46  (FIG. 2D) in # 5  plug. 
     FIGS. 6-6D show # 6  plug, an alternate embodiment of our “Connector Thermal Sensor”. This plug is a replaceable nose or contact section. The # 6  plug is fitted to the contact end of certain aircraft ground power plugs, similar to # 1  plug (FIGS.  1 - 1 E), to enhance repairability. 
     This alternate embodiment places an additional thermal sensor  30 , thermal sensor cavity  34 , and cavity seal  38  near power contact socket  26  [N]. 
     Thermal sensors  30  (FIGS. 6A &amp; 6B) are shown electrically connected in series. 
     Figure descriptions for # 5  plug (FIGS. 5-5E) apply to # 6  plug (FIGS.  6 - 6 D), with the inclusion of an additional thermal sensor  30 , thermal sensor cavity  34 , and cavity seal  38  in plug # 6 . 
     Operation, FIGS.  1  through  6 D 
     Electrical # 1  plug  20 , illustrated in FIGS. 1-1E, is atypical of the devices presently used to connect a source of electric power to a load, typically an aircraft that is parked. 
     Ground power # 1  plug  20  is used herein as a reference for an “unprotected plug”. Each plug, # 2  through # 6  (FIGS.  2 - 6 D), is presently in use without our “Connector Thermal Sensor” invention. 
     A problem that occurs with some frequency is excess contact temperature on power contact socket  26  (FIGS.  1 - 6 D). This excess temperature is caused, for instance, by excessive electrical contact resistance between power contact socket  26  and the mating receptacle, usually on an aircraft. The contacts with excessive resistance may be only one or all power contacts  26 . 
     Additionally, any power connections that are improper, within the ground power plugs (FIGS. 1-6D) or the mating receptacle, will cause unacceptable temperatures to be produced. 
     The result of excessive electrical resistance at or near power contact  26  is the production of a large amount of heat. As the heat increases, the contact electrical resistance increases. The heat build-up causes damage to plug  20  (FIG.  1 D), the aircraft connector, and aircraft connector wiring. 
     Our “Connector Thermal Sensor” provides a means to detect the presence of excess heat in the areas about power contact sockets  26  (FIGS.  1 - 6 D). 
     Our “Connector Thermal Sensor” consists of the placement of a thermal sensor  30  in close proximity to power contact sockets  26  (FIGS. 2 &amp; 2B typical). Thermal sensor cavity  34  encompasses thermal sensor  30 . Cavity seal  38  provides exclusion of the environment from the cavity. More than one thermal sensor may be provided (FIGS. 3,  3 B,  6 ,  6 A). 
     Thermal sensor  30  is a device of variable properties. The properties must be such that a significant change in the resistance or conductance of thermal sensor  30  will occur at a predetermined temperature. The magnitude of this change must be sufficient to cause control circuits, connected via control conductors  24  and power cable  46  (FIGS.  2 B &amp;  2 D), to respond. The response of the control circuits will cause a change in power flow to the connected load, thus affecting the heat level at thermal sensor cavity  34 . 
     In most instances, thermal sensor  30  will be a normally closed, contact type switch. The switch would open on rising temperature. 
     In most instances, operation of thermal sensor  30  would cause control circuits to immediately discontinue power to the load. 
     Thermal sensor  30  will self-reset once the temperature in thermal sensor cavity  38  is reduced to an acceptable level. 
     With our “Connector Thermal Sensor”, protection against excess temperature damage is afforded to both the ground power connecting plug (FIGS. 2-6D) and the mating receptacles. 
     CONCLUSIONS, RAMIFICATIONS, AND SCOPE 
     Accordingly, it can be seen that the Connector Thermal Sensor invention will provide a high degree of thermal protection for the aircraft ground power receptacle and its electrical wiring. Additionally, the plug on the ground power cable is simultaneously thermally protected. 
     Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Various other embodiments and ramifications are possible within its scope. For example, ground power cables used as extensions or for interconnecting equipment with similar or identical connectors will be afforded the same thermal protection. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.