Semi-passive linear actuator

1. A linear actuator comprising:

a housing having at least one wall made from an electrochromatic material configured to transform from an opaque to a translucent material in response to a voltage;

a plunger slidably coupled to the housing to move between a first position and a second position; and

an actuator disposed between the plunger and the housing, the actuator being made from a heat sensitive material, the actuator being configured to change a length of the actuator in response to a change in temperature.

2. The linear actuator of claim 1 , wherein the actuator is made from a polymer fiber.

3. The linear actuator of claim 2 , wherein the polymer fiber includes one of a polyethylene or a polyamide having two monomers containing six carbon atoms.

4. The linear actuator of claim 1 , further comprising a power source electrically coupled to the at least one wall.

5. The linear actuator of claim 1 , further comprising a biasing member coupled to the plunger, the biasing member biasing the plunger towards the first position.

6. The linear actuator of claim 1 , further comprising a heating element thermally coupled to the actuator.

7. The linear actuator of claim 6 , wherein the heating element includes a coil member disposed about the actuator.

8. The linear actuator of claim 7 , wherein the coil member is configured to selectively heat or cool the actuator.

9. The linear actuator of claim 6 , wherein the coil member biases the plunger towards the first position.

10. A method of operating a linear actuator comprising:

applying a voltage to an electrochromatic wall of a housing;

allowing sunlight to increase a temperature within the housing based at least in part on the applying of the voltage to the electrochromatic wall;

changing a length of an actuator from a first length to a second length in response to the increase in the temperature of the housing, the second length being smaller than the first length; and

moving a plunger in a first direction in response to the actuator changing from the first length to the second length.

11. The method of claim 10 , further comprising:

removing the voltage from the electrochromatic wall of the housing;

reducing the temperature within the housing in response to the voltage being removed from the electrochromatic wall;

changing the length of the actuator from the second length to the first length in response to the reducing of the temperature within the housing; and

moving the plunger in a second direction in response to the changing of the length of the actuator, the second direction being opposite the first direction.

12. The method of claim 11 , further comprising biasing the plunger in the second direction.

13. The method of claim 11 , further comprising applying supplemental heat to the housing in response to the temperature within the housing not increasing to a threshold temperature within a predetermined amount of time.

14. The method of claim 13 , wherein the supplemental heat is applied with a resistance heater disposed within the housing.

15. The method of claim 13 , wherein the supplemental heat is applied by a member coiled about the actuator.

16. The method of claim 15 , further comprising removing heat from the housing with the member in response to the removing of the voltage.

17. A linear actuator comprising:

a power supply;

a housing having a first portion made from an electrochromatic material configured to transform from an opaque to a translucent material in response to a voltage from the power supply;

a plunger slidably coupled to the housing to move between a first position and a second position; and

an actuator disposed between the plunger and the housing, the actuator being made from a heat sensitive material, the actuator being configured to change a length of the actuator in response to a change in temperature, the actuator being a coiled polymer fiber.

18. The linear actuator of claim 17 , further comprising a supplemental heater thermally coupled to the actuator.

19. The linear actuator of claim 18 , wherein the supplemental heater includes a conductive wire disposed inside or about the outside of the coiled polymer fiber.

20. The linear actuator of claim 19 , wherein the coiled polymer fiber includes one of a polyethylene or a polyamide having two monomers containing six carbon atoms.