Heat sensor
A thermal sensor with a simple structure can secure the deformability of a bimetal, and accurately control the position of the bimetal, to increase the response speed (heat response) of the bimetal. The thermal sensor includes a bimetal, a case, and a cover member. A pressing portion is provided between the cover member and the bimetal to press the bimetal to a bottom portion of the case. The pressing portion is deformable in accordance with the deformation of the bimetal.
1. A thermal sensor comprising:
a thermally deformable bimetal in one direction;
a case which accommodates the bimetal and transfers external heat to the bimetal;
a cover member which occludes an aperture of the case into which the bimetal is inserted; and
a pressing holder provided between the cover member and the bimetal to press the bimetal in the opposite direction to the one direction, wherein
the pressing holder includes a number of legs extending to an edge of the bimetal from the cover member; and
the legs each include a pressing portion which contacts a cover-member-side surface of the bimetal adjacent to the edge and directly presses the edge of the bimetal in the opposite direction.
2. The thermal sensor according to claim 1 , further comprising:
a manipulation rod which moves along with the deformation of the bimetal;
a switch which turns on or off in accordance with a motion of the manipulation rod, wherein the pressing holder and the manipulation rod are different components.
3. The thermal sensor according to claim 1 , wherein
the bimetal is of a concaved or convexed disc shape; and
the legs are provided to equally press three or more circumferential locations of the edge of the disc-shaped bimetal.
4. The thermal sensor according to claim 1 , wherein
the cover member includes a protrusion on a bimetal-side surface; and
the pressing holder includes a cover engaging portion which engages with the protrusion and an edge abutter which abuts on the edge of the bimetal.
5. The thermal sensor according to claim 1 , wherein
the pressing holder is made from a material with a heat transfer coefficient lower than a heat transfer coefficient of the bimetal.
6. The thermal sensor according to claim 1 , wherein
the pressing holder presses the bimetal with a force smaller than a deforming force of the bimetal.
7. The thermal sensor according to claim 2 , wherein
the cover member includes a protrusion on a bimetal-side surface; and
the pressing holder includes a cover engaging portion which engages with the protrusion and an edge abutter which abuts on the edge of the bimetal.
8. The thermal sensor according to claim 3 , wherein
the cover member includes a protrusion on a bimetal-side surface; and
the pressing holder includes a cover engaging portion which engages with the protrusion and an edge abutter which abuts on the edge of the bimetal.
9. The thermal sensor according to claim 2 , wherein
the pressing holder is made from a material with a heat transfer coefficient lower than a heat transfer coefficient of the bimetal.
10. The thermal sensor according to claim 3 , wherein
the pressing holder is made from a material with a heat transfer coefficient lower than a heat transfer coefficient of the bimetal.
11. The thermal sensor according to claim 4 , wherein
the pressing holder is made from a material with a heat transfer coefficient lower than a heat transfer coefficient of the bimetal.
12. The thermal sensor according to claim 2 , wherein
the pressing holder presses the bimetal with a force smaller than a deforming force of the bimetal.
13. The thermal sensor according to claim 3 , wherein
the pressing holder presses the bimetal with a force smaller than a deforming force of the bimetal.
14. A thermal sensor comprising:
a thermally deformable bimetal in one direction and having a concaved or convexed disc shape;
a case which accommodates the bimetal and transfers external heat to the bimetal;
a cover member which occludes an aperture of the case into which the bimetal is inserted;
a manipulation rod which contacts a central portion of the bimetal and moves along with the deformation of the bimetal;
a switch which turns on or off in accordance with a motion of the manipulation rod and
a pressing holder provided between the cover member and the bimetal to press the bimetal in the opposite direction to the one direction, wherein
the pressing holder includes a number of legs extending to an edge of the bimetal from the cover member and deforming in accordance with a deformation of the bimetal;
the legs each include a pressing portion which contacts a cover-member-side surface of the bimetal adjacent to the edge and directly presses the edge of the bimetal in the opposite direction; and
the legs are provided to equally press three or more circumferential locations of the edge of the disc-shaped bimetal.
15. The thermal sensor according to claim 14 , wherein
the cover member includes a protrusion on a bimetal-side surface; and
the pressing holder includes a cover engaging portion which engages with the protrusion and an edge abutter which abuts on the edge of the bimetal.
16. The thermal sensor according to claim 14 , wherein
the pressing holder is made from a material with a heat transfer coefficient lower than a heat transfer coefficient of the bimetal.
17. The thermal sensor according to claim 14 , wherein
the pressing holder presses the bimetal with a force smaller than a deforming force of the bimetal.