Bimetal thermal element and the manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-10368398-B2
Application number	US-201214236680-A
Country	US
Kind code	B2
Filing date	Mar 6, 2012
Priority date	Aug 3, 2011
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

A bimetal thermal element adapted to assembling into a support. The bimetal thermal element includes: a bimetal strip having a first end and a second end opposite to the first end, and a notch formed at the first end; a heater made of a resistant strip including a linear portion and a wound portion, wherein the linear portion is straight and extending from a first position near the second end of the bimetal strip in a direction parallel to the bimetal strip and the wound portion is wound around the bimetal strip and the linear portion; and an insulating device to insulate the bimetal strip from the heater. With this design, there is also no current within the bimetal strip and its support, so the deflection of the bimetal strip is generated only by the temperature-rise coming from the resistant strip, therefore, it can realize a long tripping time.

First claim

The invention claimed is:

1. A bimetal thermal element adapted to assembling into a support, comprising:
a bimetal strip having a first end, a second end opposite to the first end, and a notch formed at the first end;
a heater made of a resistant strip including a linear portion and a wound portion, wherein the linear portion is straight and extending from a starting position near the second end of the bimetal strip to the notch in a direction parallel to a side of the bimetal strip and the wound portion of the resistant strip is folded around the notch of the bimetal strip so as to wind around the bimetal strip and the linear portion of the resistant strip; and
an insulating device to insulate the bimetal strip from the heater.

2. The bimetal thermal element according to claim 1 , wherein:
the wound portion of the resistant strip includes a first portion folded around the notch of the bimetal strip and a second portion wound around the bimetal strip and the linear portion of the resistant strip;
the second portion of the wound portion of the resistant strip starts from a side of the bimetal strip opposite to where the linear portion is set; and
the second portion of the wound portion of the resistant strip is coupled to the linear portion of the resistant strip via the first portion of the wound portion.

3. The bimetal thermal element according to claim 2 , the dimensions of the bimetal strip and the resistant strip satisfying the following condition:
D>W /cosine β,

wherein, D is the length of an edge of the notch around which the first portion of the wound portion of the resistant strip is folded, W is the width of the resistant strip, and 3 is the incline angle of the edge of the notch.

4. The bimetal thermal element according to claim 2 , the dimensions of the bimetal strip and the resistant strip satisfying the following condition:
A=W ·TAN β,

wherein, A is the length of the first portion of the wound portion of the resistant strip, W is the width of the resistant strip, and β is the incline angle of an edge of the notch around which the first portion of the wound portion of the resistant strip is folded.

5. The bimetal thermal element according to claim 2 , wherein the dimension of the bimetal strip and the resistant strip satisfies the following condition:
β=(90°−α)/2,

wherein, β is the incline angle of an edge of the notch around which the first portion of the wound portion of the resistant strip is folded, and α is a winding angle of the wound portion of the resistant strip.

6. The bimetal thermal element according to claim 2 , wherein the resistant strip further includes a folded portion folded from the starting position of the linear portion with a folding angle.

7. The bimetal thermal element according to claim 6 , wherein the folding angle is 45° to result in a right angle between the linear portion and the folded portion of the resistant strip.

8. The bimetal thermal element according to claim 2 , wherein the resistant strip further includes a terminal portion stretching from the second portion of the wound portion of the resistant strip.

9. The bimetal thermal element according to claim 1 , wherein the insulating device includes a sheath adapted to preventing the second portion of the wound portion of the resistant strip from touching the linear portion of the resistant strip and the bimetal strip.

10. The bimetal thermal element according to claim 9 , wherein the insulating device further includes a sheet adapted to insulating the linear portion and the first portion of the wound portion of the resistant strip from the bimetal strip.

11. The bimetal thermal element according to claim 1 , wherein the insulating device completely insulates the bimetal strip from the resistant strip.

12. The bimetal thermal element according to claim 1 , further including a fixing point between the bimetal strip and linear portion of the resistant strip, near the starting position of the linear portion.

13. The bimetal thermal element according to claim 12 , wherein the insulating device insulates the bimetal strip from the resistant strip except the portion adjacent the fixing point.

14. The bimetal thermal element according to claim 1 , wherein the bimetal strip is made of two layers.

15. The bimetal thermal element according to claim 1 , wherein the bimetal strip has a first side with higher thermal expansion coefficient and a second side with lower thermal expansion coefficient, the linear portion of the resistant strip is set on the second side of the bimetal strip.

16. A method for manufacturing a bimetal thermal element, comprising:
preparing a bimetal strip including a notch at a first end thereof;
positioning a resistant strip parallel to a side of the bimetal strip with a starting position of a first portion thereof adjacent a second end of the bimetal strip opposite to the first end;
extending the first portion of the resistant strip from the starting position toward to the notch;
enclosing the bimetal strip and the resistant strip with an insulating sheath;
folding the first portion of the resistant strip along an edge of the notch of the bimetal strip with a linear portion of the resistant strip parallel to the side of the bimetal strip; and
folding a wound portion of the first portion of the resistant strip around the notch of the bimetal strip so as to wind around the linear portion of the first portion of the resistant strip and the bimetal strip at a predetermined winding angle.

17. The method according to claim 16 , further comprising: fixing the linear portion of the resistant strip and bimetal strip at a position adjacent the starting position of the first portion of the resistant strip before enclosing the bimetal strip and the resistant strip with the insulating sheath.

18. The method according to claim 16 , further comprising: putting an insulating sheet between the bimetal strip and the linear portion of the resistant strip with a part having a specific shape at a head of the insulation sheet adapted to being folded later to cover an edge of the notch before enclosing the bimetal strip and the resistant strip with the insulating sheath.

19. The method according to claim 16 , further comprising: folding the resistant strip at a folding angle to divide the resistant strip into the first portion and a second portion before positioning the resistant strip parallel to the side of the bimetal strip with the starting position of the first portion of the resistant strip near the second end of the bimetal strip opposite to the first end.

20. The method according to claim 17 , further comprising: putting an insulating sheet between the bimetal strip and the linear portion of the resistant strip with a part having a specific shape at a head of the insulation sheet adapted to being folded later to cover an edge of the notch before enclosing the bimetal strip and the resistant strip with the insulating sheath.

21. The method according to claim 17 , further comprising: folding the resistant strip at a folding angle to divide the resistant strip into the first portion and a second portion before positioning the resistant strip parallel to the side of the bimetal strip with the starting position of the first portion of the resistant strip near the second end of the bimetal strip opposite to the first end.

Assignees

• Bizard Bernard
• Schneider Electric Ind Sas

Inventors

• Bizard Bernard

Classifications

• Y10T29/49083

  Heater type · CPC title

• H05B3/02 Primary

  Details · CPC title

• H01H71/164 Primary

  Heating elements · CPC title

• H01H69/00

  Apparatus or processes for the manufacture of emergency protective devices · CPC title