Passive thermally-switched heat transfer system
View Patent ↗A heat transfer system includes a heat-conducting frame having a base in thermal engagement with a heat source and two legs extending from the base. A wax motor in thermal engagement with one of the frame's legs has a piston that moves towards the frame's second leg when the heat source is heated to a temperature threshold. A thermal conductor's first end is disposed between the piston and the frame's second leg, and the thermal conductor's second end is in thermal engagement with a cold source. Springs coupled to the thermal conductor move its first end into thermal engagement with the frame's second leg in correspondence with movement of the piston when the heat source is heated to the temperature threshold. The springs also move the thermal conductor's first end out of thermal engagement with the frame's second leg when the heat source is cooled to below the temperature threshold.
1 . A passive thermally-switched heat transfer system, comprising:
a heat-conducting frame having a base, a first leg extending from said base, and a second leg extending from said base wherein said first leg and said second leg are disposed in spaced-apart opposition, said base adapted to be in thermal engagement with a heat source;
a wax motor coupled to and in thermal engagement with said first leg, said wax motor having a piston operable for movement towards said second leg when the heat source is heated to a temperature threshold;
a thermal conductor having a first end and a second end, said first end disposed between said piston and said second leg, and said second end adapted to be in thermal engagement with a cold source; and
a set of springs coupled to said first end of said thermal conductor, said set of springs operable to move said first end into thermal engagement with said second leg in correspondence with said movement of said piston when the heat source is heated to the temperature threshold, and said set of springs operable to move said first end out of thermal engagement with said second leg when the heat source is cooled to below the temperature threshold.
2 . The passive thermally-switched heat transfer system of claim 1 , wherein said thermal conductor comprises a heat pipe.
3 . The passive thermally-switched heat transfer system of claim 1 , further comprising a spring-compression adjuster coupled to at least one spring from said set of springs, said spring-compression adjuster operable to change spring force of said at least one spring.
4 . The passive thermally-switched heat transfer system of claim 1 , further comprising a thermally-conductive housing coupled to and in thermal engagement with said first end, said housing having a face whose surface area is greater than said first end wherein said face is moved into contact with said second leg in correspondence with said movement of said piston when the heat source is heated to the temperature threshold.
5 . The passive thermally-switched heat transfer system of claim 1 , wherein said set of springs comprises two axially aligned compression springs.
6 . A passive thermally-switched heat transfer system, comprising:
a heat-conducting U-shaped frame having a base, a first leg extending from said base, and a second leg extending from said base;
a sheet of thermal interface material in thermal contact with said base and adapted to be in contact with at least one electronics component mounted on a printed circuit board;
a wax motor coupled to and in thermal engagement with said first leg, said wax motor having a piston operable for movement towards said second leg when the at least one electronics component is in operation and is heated to a threshold temperature;
a thermal conductor having a first end and a second end, said first end disposed between said piston and said second leg, and said second end adapted to be in thermal engagement with a cold source; and
a set of springs coupled to said first end of said thermal conductor, said set of springs operable to move said first end into thermal engagement with said second leg in correspondence with said movement of said piston when the at least one electronics component is heated to the threshold temperature, and said set of springs operable to move said first end out of thermal engagement with said second leg when the at least one electronics component cools to below the threshold temperature.
7 . The passive thermally-switched heat transfer system of claim 6 , wherein said thermal conductor comprises a heat pipe.
8 . The passive thermally-switched heat transfer system of claim 6 , further comprising a spring-compression adjuster coupled to at least one spring from said set of springs, said spring-compression adjuster operable to change spring force of said at least one spring.
9 . The passive thermally-switched heat transfer system of claim 6 , further comprising a thermally-conductive housing coupled to and in thermal engagement with said first end, said housing having a face whose surface area is greater than said first end wherein said face is moved into contact with said second leg in correspondence with said movement of said piston when the heat source is heated to the temperature threshold.
10 . The passive thermally-switched heat transfer system of claim 6 , wherein said set of springs comprises two axially aligned compression springs.
11 . A passive thermally-switched heat transfer system, comprising:
a thermally-conductive case adapted to be disposed in a space environment;
a printed circuit board (PCB) mounted in said case;
at least one electronics component mounted on said PCB, said at least one electronics component operable to perform at least one function in the space environment wherein said at least one electronics component generates heat;
a heat-conducting U-shaped frame having a base, a first leg extending from said base, and a second leg extending from said base;
a sheet of thermal interface material in thermal contact with said base and said at least one electronics component;
a wax motor coupled to and in thermal engagement with said first leg, said wax motor having a piston operable for movement towards said second leg when said heat generated by said at least one electronics component attains a threshold temperature;
a thermal conductor having a first end and a second end, said first end disposed between said piston and said second leg, and said second end in thermal engagement with said case; and
a set of springs coupled to said first end of said thermal conductor, said set of springs operable to move said first end into thermal engagement with said second leg in correspondence with said movement of said piston when said at least one electronics component attains said threshold temperature, and said set of springs operable to move said first end out of thermal engagement with said second leg when said at least one electronics component cools to below said threshold temperature.
12 . The passive thermally-switched heat transfer system of claim 11 , wherein said thermal conductor comprises a heat pipe.
13 . The passive thermally-switched heat transfer system of claim 11 , further comprising a spring-compression adjuster coupled to at least one spring from said set of springs, said spring-compression adjuster operable to change spring force of said at least one spring.
14 . The passive thermally-switched heat transfer system of claim 11 , further comprising a thermally-conductive housing coupled to and in thermal engagement with said first end, said housing having a face whose surface area is greater than said first end wherein said face is moved into contact with said second leg in correspondence with said movement of said piston when said at least one electronics component generates said heat that is at or above said threshold temperature.
15 . The passive thermally-switched heat transfer system of claim 11 , wherein said set of springs comprises two compression springs disposed on opposing sides of said first end.
16 . The passive thermally-switched heat transfer system of claim 15 , further comprising a thermally-insulating piston head coupled to said piston and in engagement with one of said two compression springs.
17 . The passive thermally-switched heat transfer system of claim 16 , wherein said one of said two compression springs generates resistance to said movement of said piston when said at least one electronics component generates said heat that is at or above said threshold temperature.
18 . The passive thermally-switched heat transfer system of claim 11 , further comprising a thermally-conducting sleeve receiving said second end of said thermal conductor, said thermally-conductive sleeve coupled to and in thermal engagement with said case.