Self-actuated defogger system
View Patent ↗A defogger system includes structure defining a window or a mirror, a heating element operatively connected to the structure to selectively apply heat to the structure, and a source of electrical energy. The defogger system also includes a switch and an electrically conductive path from the source of electrical energy to the heating element. The switch includes an active material member, and is configured such that the switch interrupts the electrically conductive path when the active material member is above a predetermined temperature. The switch is also configured such that the switch does not interrupt the electrically conductive path when the active material member is below the predetermined temperature.
1. A defogger system comprising:
structure defining a window or a mirror;
a heating element operatively connected to the structure to selectively apply heat to the structure;
a source of electrical energy;
an electrically conductive path from the source of electrical energy to the heating element; and
a switch having an active material member that is configured such that the switch interrupts the electrically conductive path when the active material member is above a predetermined temperature, and such that the switch does not interrupt the electrically conductive path when the active material member is below the predetermined temperature.
2. The defogger system of claim 1 , wherein the active material member is configured to automatically assume a first shape when the active material member is above the predetermined temperature; and
wherein the switch is configured such that the active material member assumes a second shape when the active material member is below the predetermined temperature.
3. The defogger system of claim 2 , wherein the switch includes a first electrical contact and a second electrical contact; and
wherein the active material member is operatively connected to the first electrical contact such that the first electrical contact contacts the second electrical contact when the active material member has assumed the second shape, and such that the first electrical contact does not contact the second electrical contact when the active material member has assumed the first shape.
4. The defogger system of claim 3 , wherein the switch includes a spring that biases the first electrical contact into contact with the second electrical contact.
5. The defogger system of claim 3 , wherein the active material member comprises shape memory alloy.
6. The defogger system of claim 3 , wherein active material member is in contact with the structure.
7. The defogger system of claim 6 , wherein the structure defines a groove; and
wherein the active material member is at least partially disposed within the groove.
8. The defogger system of claim 7 , wherein the size of the groove is such that the structure exerts a greater reaction force on the active material member when the active material member assumes the first shape than when the active material member assumes the second shape.
9. The defogger system of claim 8 , wherein the active material member comprises shape memory alloy.
10. A vehicle comprising:
an automotive vehicle body including structure;
a source of electrical energy; and
a defogger system including a heating element operatively connected to the structure to selectively apply heat to the structure, an electrically conductive path from the source of electrical energy to the heating element, and a switch;
wherein the switch includes an active material member that is configured such that the switch interrupts the electrically conductive path when the active material member is above a predetermined temperature, and such that the switch does not interrupt the electrically conductive path when the active material member is below the predetermined temperature.
11. The vehicle of claim 10 , wherein the active material member is configured to automatically assume a first shape when the active material member is above a predetermined temperature; and
wherein the switch is configured such that the active material member assumes a second shape when the active material member is below the predetermined temperature.
12. The vehicle of claim 11 , wherein the switch includes a first electrical contact and a second electrical contact; and
wherein the active material member is operatively connected to the first electrical contact such that the first electrical contact contacts the second electrical contact when the active material member has assumed the second shape, and such that the first electrical contact does not contact the second electrical contact when the active material member has assumed the first shape.
13. The vehicle of claim 12 , wherein the switch includes a spring that biases the first electrical contact into contact with the second electrical contact.
14. The vehicle of claim 13 , wherein the active material member comprises shape memory alloy.
15. The vehicle of claim 12 , wherein active material member is in contact with the structure.
16. The vehicle of claim 15 , wherein the structure defines a groove; and
wherein the active material member is at least partially disposed within the groove.
17. The vehicle of claim 16 , wherein the size of the groove is such that the structure exerts a greater reaction force on the active material member when the active material member assumes the first shape than when the active material member assumes the second shape.
18. The vehicle of claim 17 , wherein the active material member comprises shape memory alloy.
19. The vehicle of claim 10 , wherein the structure defines a window.
20. The vehicle of claim 10 , wherein the structure defines a mirror.