US 8,938,965 B1Granted

Thermal powered reciprocating-force motor

AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration

InventorsPaul F. Tatum, III, Amelia McDow Elliott

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Abstract

A thermal-powered reciprocating-force motor includes a shutter switchable between a first position that passes solar energy and a second position that blocks solar energy. A shape memory alloy (SMA) actuator is coupled to the shutter to control switching thereof between the shutter's first and second position. The actuator is positioned with respect to the shutter such that (i) solar energy impinges on the SMA when the shutter is in its first position so that the SMA experiences contraction in length until the shutter is switched to its second position, and (ii) solar energy is impeded from impingement on the SMA when the shutter is in its second position so that the SMA experiences extension in length. Elastic members coupled to the actuator apply a force to the SMA that aids in its extension in length until the shutter is switched to its first position.

Claims8

Dependent claims

A thermal-powered reciprocating-force motor, comprising:

a shutter switchable between a first position adapted to allow passage of solar energy and a second position adapted to block passage of solar energy;
an actuator having opposing ends, said actuator including a shape memory alloy (SMA) that changes in length as a function of temperature, said actuator coupled to said shutter for controlling switching thereof between said first position and said second position based on length of said SMA, said actuator positioned with respect to said shutter such that (i) solar energy is adapted to impinge on said SMA when said shutter is in said first position wherein said SMA experiences contraction in length until said shutter is switched to said second position, and (ii) solar energy is adapted to be impeded from impingement on said SMA when said shutter is in said second position wherein said SMA experiences extension in length;
an elastic member coupled to each of said opposing ends of said actuator for applying a force to said SMA that aids in said extension in length until said shutter is switched to said first position;
and
reflective material directly in contact with said shutter for reflecting said solar energy towards said actuator when said shutter is in said first position and for reflecting said solar energy away from said actuator when said shutter is in said second position.

2 more elements

A thermal-powered reciprocating-force motor, comprising:

a shutter switchable between a first position adapted to transmit thermal energy and a second position adapted to block thermal energy;
an actuator having opposing ends, said actuator including a shape memory alloy (SMA) that experiences linear contraction when heated and then linear extension when subsequently cooled, said actuator coupled to said shutter for controlling switching thereof from said first position to said second position during said linear contraction and for switching said shutter from said second position to said first position during said linear extension, said actuator positioned with respect to said shutter such that (i) thermal energy transmitted by said shutter in said first position reaches said SMA, and (ii) thermal energy blocked by said shutter in said second position is prevented from reaching said SMA;
an elastic member coupled to each of said opposing ends of said actuator for applying a force to said SMA that aids said linear extension until said shutter is switched to said first position;
and
reflective material coating said shutter for movement therewith, said reflective material directing said thermal energy towards said actuator when said shutter is in said first position and directing said thermal energy away from said actuator when said shutter is in said second position.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/118,086Filed 27 May 2011
Granted: 27 Jan 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

F03G 7/0614
Characterised by the actuating element: using shape memory elements
F03G 7/062
Using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like: characterised by the activation arrangement
B60K 2016/003
Arrangements in connection with power supply of propulsion units in vehicles from forces of nature, e.g. sun or wind: solar power driven
B60Y 2200/46
Special vehicles: arctic-/Extraterrestric explorers