Temperature sensor for a resistance thermometer, in particular for use in the exhaust gas system of combustion engines
View Patent ↗The invention describes a temperature sensor for a, resistance thermometer having an electric measuring resistor the resistance material of which consists either of a ceramic material or of a metallic resistance material in combination with a ceramic or a mineral carrier; having a protective tube comprising a closed tip and a rear end that provides an access to the inner space of the protective tube and that contains the measuring resistor; having at least one connection wire of the measuring resistor that is brought out through the rear end of the protective tube; and having an electrically insulating filler based on a ceramic or a mineral material that fills the space between the protective tube on the one side and the measuring resistor on the other side. It is provided according to the invention that the filler extends substantially over the length of the measuring resistor, while leaving exposed the at least one connection wire that extends from the carrier; that the at least one connection wire is connected with an inner conductor of a mineral-insulated or a ceramic-insulated metal-sheathed cable; that the metal sheath of the cable is connected with the rear end of the protective tube by a metallic sleeve; and that an expansion compensating means for the at least one connection wire of the measuring resistor is arranged in the sleeve.
1. Temperature sensor for a resistance thermometer
having an electric measuring resistor the resistance material of which consists either of a ceramic material or of a metallic resistance material in combination with a ceramic or a mineral carrier;
having a protective tube comprising a closed tip and a rear end that provides an access to the inner space of the protective tube and that contains the measuring resistor;
having at least one connection wire of the measuring resistor that is brought out through the rear end of the protective tube;
and having an electrically insulating filler based on a ceramic or a mineral material that fills the space between the protective tube on the one side and the measuring resistor on the other side,
wherein the filler extends substantially over the length of the measuring resistor, while leaving exposed the at least one connection wire that extends from the carrier;
that the at least one connection wire is connected with an inner conductor of a mineral-insulated or a ceramic-insulated metal- sheathed cable;
that the metal sheath of the cable is connected with the rear end of the protective tube by a metallic sleeve;
and that an expansion compensating means for the at least one connection wire of the measuring resistor is arranged in the sleeve.
2. The temperature sensor as defined in claim 1 , wherein the expansion compensating means has a resilient design.
3. The temperature sensor as defined in claim 1 , wherein the expansion compensating means is a bent section of the at least one connection wire and/or of the inner conductor of the cable fixed thereon.
4. The temperature sensor as defined in claim 1 , wherein the filler fills the protective tube up to its rear end and that the carrier projects beyond the rear end of the protective tube and into the sleeve.
5. The temperature sensor as defined in claim 1 , wherein the protective tube comprises a cylindrical rear section, a narrower forward section, compared with the rear section, and a transition portion.
6. The temperature sensor as defined in claim 5 , wherein the forward section of the protective tube exhibits a substantially constant cross-section.
7. The temperature sensor as defined in claim 1 , wherein the protective tube consists of a metal.
8. The temperature sensor as defined in claim 7 , wherein the protective tube consists of a highly temperature-resistant alloy, especially of a nickel alloy such as Inconel, especially of Inconel 600 or of Inconel 601.
9. The temperature sensor as defined in claim 1 , wherein magnesium oxide powder, aluminum oxide powder, aluminum nitride powder or mixtures thereof are provided as the filler.
10. The temperature sensor as defined in any of claim 1 , wherein a ceramic casting compound, a ceramic adhesive or a highly temperature-resistant heat-transfer paste is provided as filler.
11. The temperature sensor as defined in claim 1 , wherein the measuring resistor has a negative temperature coefficient.
12. The temperature sensor as defined in claim 1 , wherein the measuring resistor is a flat measuring resistor.
13. The temperature sensor as defined in claim 1 , wherein the measuring resistor is formed using platinum or a platinum alloy.
14. The temperature sensor as defined in claim 13 in which the measuring resistor is a Pt-100 or Pt-200 resistor.
15. The temperature sensor as defined in claim 12 in which the measuring resistor is formed using platinum or a platinum alloy as the resistance material.
16. The temperature sensor as defined in claim 2 , wherein the expansion compensating means is a bent section of the at least one connection wire and/or of the inner conductor of the cable fixed thereon.
17. The temperature sensor as defined in claim 2 , wherein the filler fills the protective tube up to its rear end and that the carrier projects beyond the rear end of the protective tube and into the sleeve.
18. The temperature sensor as defined in claim 3 , wherein the filler fills the protective tube up to its rear end and that the carrier projects beyond the rear end of the protective tube and into the sleeve.
19. The temperature sensor as defined in claim 16 , wherein the filler fills the protective tube up to its rear end and that the carrier projects beyond the rear end of the protective tube and into the sleeve.
20. The temperature sensor as defined in claim 2 , wherein the protective tube comprises a cylindrical rear section, a narrower forward section, compared with the rear section, and a transition portion.