Temperature responsive apparatus for detecting heat leaks

Claim 2

A hand-held, battery-operated, temperature-difference, ambient air measuring apparatus comprising a temperature sensitive probe having a housing for mounting a low thermal-mass thermistor in an ambient air exposed position, said housing having means for mounting said low thermal-mass thermistor in said ambient air exposed position out of contact with any heat sinking means and means for protecting said low thermal-mass thermistor from accidential contact with potentially damaging mechanical elements, an electrical temperature-difference measuring circuit, means for connecting said thermistor to said electrical temperature-difference measuring circuit, said electric circuit comprising a comparison circuit for comparing a temperature signal representative of the impedance of the thermistor with a presettable reference standard signal for providing an output signal which varies as a function of a difference between said temperature signal and said reference standard, and an indicator responsive to said electrical circuit for providing an indication of the value of the output signal.

Claim 3

The temperature-difference measuring apparatus of claim 1 wherein said comparison circuit comprises a difference amplifier having first and second inputs, and an output proportional, over a linear operating range of the amplifier, to the voltage difference of the inputs, and wherein said reference standard signal is one of said inputs and the temperature signal is the other of said inputs, and said indicator is a current responsive meter driven by said difference amplifier.

Claim 4

A hand-held, battery-operated, temperature-difference measuring apparatus comprising a temperature sensitive probe having a housing for protectively mounting a low thermal-mass thermistor, said housing having an elongated, hollow cylindrical element adapted to support said thermistor at one end thereof and said thermistor having a body portion extending beyond said one end, a low thermal-mass, gas porous, cylindrically-shaped member fitting over and supported by an outside periphery of said one end of said element and extending from said element beyond the physical extent of said supported thermistor body, and said member acting to physically protect said thermistor body portion while permitting the substantially unobstructed flow of air to the thermistor, an electrical temperature-difference measuring circuit, means for connecting said thermistor to said electrical temperature-difference measuring circuit, said electrical circuit comprising a comparison circuit for comparing a temperature signal representative of the impedance of the thermistor with a presettable reference standard signal for providing an output signal which varies as a function of a difference between said temperature signal and said reference standard, and an indicator reponsive to said electrical circuit for providing an indication of the value of the output signal.

Claim 5

A hand-held, battery-operated, temperature-difference measuring apparatus comprising a temperature sensitive probe having a housing for protectively mounting a low thermal-mass thermistor, said housing having an elongated, hollow cylindrical element adapted to support said thermistor at one end thereof and said thermistor having a body portion extending beyond said one end, a low thermal-mass, gas porous, cylindrically-shaped member fitting over and supported by an outside periphery of said one end of said element and extending from said element beyond the physical extent of said supported thermistor body, and said member acting to physically protect said thermistor body portion while permitting the substantially unobstructed flow of air to the thermistor, an electrical temperature-difference measuring circuit, means for connecting said thermistor to said electrical temperature-difference measuring circuit, said electrical circuit comprising a comparison circuit for comparing a temperature signal representative of the impedance of the thermistor with a presettable reference standard signal for providing an output signal which varies as a function of a difference between said temperature signal and said reference standard, and an indicator reponsive to said electrical circuit for providing an indication of the value of the output signal.

Claim 6

The temperature-difference measuring apparatus of claim 3 wherein said cylindrical member is a coil spring.

Claim 7

The temperature-difference measuring apparatus of claim 3 wherein said probe has a response time of less than about one second.

Claim 8

A hand-held, battery-operated, temperature-difference measuring apparatus comprising a hand-held temperature sensitive probe having a housing for protectively mounting a low thermal-mass thermistor, the housing having an elongated, hollow, cylindrical element adapted to support said thermistor at one end thereof and said thermistor having a body portion extending beyond said one end, and a low thermal-mass, gas porous, cylindrically-shaped spring member fitting over and supported by an outside periphery of said one end of said element, and extending from said element beyond the physical extent of said thermistor body, whereby said spring member acts to physically protect said thermistor body portion while permitting the unobstructed flow of air to the thermistor, said thermistor thereby having a response time of less than about one second, an electrical circuit, means for connecting said thermistor to said electrical circuit, said electrical circuit comprising a comparison circuit for comparing a temperature signal representative of the thermistor impedance with a presettable reference standard signal for providing an output signal which varies as a function of a difference between the temperature signal and the reference standard, the comparison circuit having a difference amplifier having first and second inputs, and an output proportional, over a linear operating range of the amplifier, to the voltage difference of the inputs, and wherein said reference standard is one of said inputs and the temperature signal is the other of said inputs, and a current responsive meter, driven by said electrical circuit output, for providing a visible indication of the value of the amplifier output signal.

Claim 9

A hand-held, battery-operated, temperature-difference measuring apparatus comprising a hand-held temperature sensitive probe having a housing for protectively mounting a low thermal-mass thermistor, the housing having an elongated, hollow, cylindrical element adapted to support said thermistor at one end thereof and said thermistor having a body portion extending beyond said one end, and a low thermal-mass, gas porous, cylindrically-shaped spring member fitting over and supported by an outside periphery of said one end of said element, and extending from said element beyond the physical extent of said thermistor body, whereby said spring member acts to physically protect said thermistor body portion while permitting the unobstructed flow of air to the thermistor, said thermistor thereby having a response time of less than about one second, an electrical circuit, means for connecting said thermistor to said electrical circuit, said electrical circuit comprising a comparison circuit for comparing a temperature signal representative of the thermistor impedance with a presettable reference standard signal for providing an output signal which varies as a function of a difference between the temperature signal and the reference standard, the comparison circuit having a difference amplifier having first and second inputs, and an output proportional, over a linear operating range of the amplifier, to the voltage difference of the inputs, and wherein said reference standard is one of said inputs and the temperature signal is the other of said inputs, and a current responsive meter, driven by said electrical circuit output, for providing a visible indication of the value of the amplifier output signal.