The present disclosure relates to heat transfer in hardened electronics, and more particularly to hardened electronics such as used in guided munitions.
There is an ever increasing need for smaller SWAP (size, weight and power) of electronics in guided munitions. As the size of these electronics decreases, the power density can drastically increase, resulting in the ever increasing need for new thermal mitigation techniques. Heatsinks or heatpipes can be used in conjunction with guided munitions to transport heat in cooling the electronics. Thermoelectric coolers (TECs) can be too weak mechanically and can therefore be unable to survive high acceleration events. Also with the desire to limit power consumption to the active electronics and potentially a limit on maximum power resources available, it is not desirable to use active cooling techniques that require power.
The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved systems and methods for cooling electronics in guided munitions. This disclosure provides a solution for this need.
A system includes a guided munition having a housing. A first reservoir is defined within the housing holding a first chemical reactant. A second reservoir is defined within the housing, wherein the second reservoir holds a second chemical reactant configured to undergo an endothermic reaction with the first chemical reactant. A frangible barrier separates between the first and second reservoirs. The frangible barrier is configured to break under forces acting on the guided munition as the guided munition is fired from a weapon.
An electronic device can be housed within the housing in thermal contact with at least one of the first reservoir and/or second reservoir for cooling the electronic device with an endothermic reaction upon mixing of the first and second chemical reactants. A mass can be included within the first reservoir configured to assist with breaking the barrier as acceleration forces the mass toward the second reservoir. The mass can be a free mass within the first reservoir. A fixed mass can be included in the second reservoir positioned so the free mass moves past the fixed mass as acceleration forces the free mass toward the second reservoir. The fixed mass can assist the free mass in breaking the frangible barrier from opposite sides. The free mass can be ring shaped and can be positioned to surround the fixed mass as acceleration forces the free mass toward the second reservoir. The free mass can be connected to a biasing member, which can be connected to the housing to hold the free mass away from the frangible barrier prior to acceleration forcing the free mass toward the second reservoir. The fixed mass can be connected to a biasing member which is connected to the housing to keep the fixed mass away from the frangible barrier prior to acceleration forcing the free mass toward the second reservoir, wherein the fixed mass is configured to compress its biasing member and become fixed relative to the housing as acceleration forces the free mass toward the second reservoir. At least one of the free mass and/or the fixed mass can include an edge or point configured to penetrate the frangible barrier.
A guided munition includes a housing with a cooling system inside the housing for cooling an internal electronic device inside the housing, wherein the cooling system is passively activated by firing the guided munition as a projectile from a weapon.
A method includes breaking a frangible barrier under forces acting on a housing of a guided munition as the guided munition is fired from a weapon. The method includes mixing a first chemical reactant from a first reservoir within the housing with a second chemical reactant from a second reservoir within the housing to cause an endothermic reaction wherein breaking the frangible barrier brings the first and second chemical reactants into contact with one another.
The method can include cooling an electronic device within the housing using the endothermic reaction. The method can include assisting mixing of the first and second chemical reactants using motion from rifling and balloting in the weapon. Breaking the frangible barrier can include using a mass within the first reservoir configured to assist with breaking the barrier as acceleration forces the mass toward the second reservoir. The mass can be a free mass within the first reservoir and a fixed mass can be included in the second reservoir positioned so the free mass moves to pass the fixed mass as acceleration forces the free mass toward the second reservoir, wherein the fixed mass assists the free mass in breaking the frangible barrier from opposite sides. The free mass can be ring shaped and is positioned to surround the fixed mass as acceleration forces the free mass toward the second reservoir.
These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an embodiment of a system in accordance with the disclosure is shown in
The system 100 includes a guided munition 102 having a housing 104. A first reservoir 106 is defined within the housing 104 holding a first chemical reactant. A second reservoir 108 is defined within the housing 104, wherein the second reservoir 108 holds a second chemical reactant configured to undergo an endothermic reaction with the first chemical reactant. A frangible barrier 110 separates between the first and second reservoirs 106, 108. The frangible barrier 110 is configured to break under forces acting on the guided munition as the guided munition is fired from a weapon, e.g. acceleration forces under acceleration in the direction indicated by the larger arrow in
An electronic device 112 is housed within the housing 104 in thermal contact with at least one of the first reservoir 106 and/or second reservoir 108 for cooling the electronic device 112 with an endothermic reaction upon mixing of the first and second chemical reactants. As indicated in
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The methods and systems of the present disclosure, as described above and shown in the drawings, provide for self-contained, passively activated electronic cooling for guided munitions. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.
This invention was made with government support under contract number 2019-535 awarded by the U.S. ARMY. The government has certain rights in the invention.
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20220163305 A1 | May 2022 | US |