Method and apparatus for inferring a temperature

• US 6,945,691 B2
• Filed: 11/27/2002
• Issued: 09/20/2005
• Est. Priority Date: 11/27/2002
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Dauer, Kenneth J., Trapasso, David J.
• Primary Examiner(s): Verbitsky, Gail
• Assistant Examiner(s): Jagan, Mirellys
• Application Number:
  US10/305,993
• Publication Number:
  US 20040101030A1
• Time in Patent Office: 1,028 Days
• Field of Search: 374/15, 374/185, 374/1, 374/172, 374/110, 374/112, 374/115, 374/144, 374/145, 374/29, 374/30, 374/43, 374/44, 374/165, 374/134, 374/135, 374/166
• US Class Current: 374/15
• CPC Class Codes: G01K 1/14 Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
• CPC Class Codes: G01K 1/16 Special arrangements for conducting heat from the object to the sensitive element
• CPC Class Codes: G01K 3/14 in respect of space

Abstract

A heat-conducting element having known length D is disposed at a first end in a first region having a first temperature T₁ to be inferred. The second end of the element is disposed in a second region having a measureable second temperature T₂ different from the first temperature. The element is well-insulated between the first and second regions. Heat flows along the element from the higher temperature region to the lower temperature region, and the temperature of the element at any point along the element is proportional to the temperature difference between the two regions and the distance from either one of the regions. By measuring the second temperature and also a third temperature T₃ at a point along the element, and knowing accurately the position D_n of that point with respect to the first and second ends of the element, the first temperature can be inferred by proportionality.

Claims

1. A method for determining by inference a first temperature T₁ in a first thermal region, comprising the steps of:

a) providing a thermally-conductive element having a known length D and extending said element into said first thermal region such that an exposed first end of said element is at said first temperature T₁ to be inferred;

b) extending said conductive element from said first thermal region into a second region having a second temperature T₂ such that an exposed second end of said element is at said second temperature T₂, wherein said thermally-conductive element is covered with an insulative covering and extends substantially the entire length between said first and second thermal regions;

c) determining said second temperature T₂;

d) determining a third temperature T₃ at a known distance D_n along said element from said second region;

e) establishing an ideal linear relationship between said first temperature T₁ and said third temperature T₃ from the relationship

T₁=[(D/D_n)(T₃−

T₂)]+T₂;

f) establishing an actual relationship between said first temperature T₁ and said third temperature T₃ by maintaining said second temperature T₂ at a constant temperature, imposing known values of said first temperature T₁, and measuring said third temperature T₃;

g) comparing said ideal linear relationship with said actual relationship to determine non-linearity characteristics of the actual relationship and

h) calculating said first temperature T₁ using the actual relationship, and compensating the calculated first temperature T₁ to remove the non-linearity characteristics.

2. A method in accordance with claim 1 wherein said first temperature T₁ is calculated using the actual relationship T₁=4E−

07T₃³−

0.0004T₃²+0.2564T₃+11.857.