Temperature calibration system

Claim 2

In a system for providing an accurate temperature for calibration of a temperature probe, the combination of: a well having a cavity with an electric resistance heater positioned about said cavity and a heat insulator positioned about said heater; first and second metal heat sinks, with each of said heat sinks positionable within said cavity for sliding insertion and removal for interchanging heat sinks, and each having a central opening for receiving a temperature probe; a first temperature sensing element mounted in said wall separate from said heat sinks; and a control circuit for energizing said heater for maintaining the temperature of the inserted heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point.

Claim 3

A system as defined in claim 8 including movable cover means of thermal insulating material carried on said well at said open top and overlying said heat sink, with an opening for passage of the temperature probe.

Claim 4

A system as defined in claim 2 in which said well includes a finned heat transfer casing for said bottle, and including: a housing; means for mounting said well in said housing with said casing spaced from the housing wall; and means for moving air through said housing past said casing.

Claim 5

A system as defined in claim 1 including: a second temperature sensing element mounted in said well; and a readout circuit for indicating the temperature of said heat sink and having said second temperature sensing element connected thereto as an input.

Claim 6

A system as defined in claim 4 in which said well includes a metal sleeve defining said cavity with said electric resistance heater wound on saId sleeve, and in which said first and second temperature sensing elements are mounted within said sleeve.

Claim 7

A system as defined in claim 5 in which said cavity and sleeve are elongate cylinders, and wherein said first and second temperature sensing elements are located adjacent thE open end of said cavity and at the same radial distance from the centerline of said cylinders.

Claim 8

In a system for providing a plurality of accurate temperatures for calibration of a temperature probe, the combination of: a housing; a plurality of wells, each of said wells having a metal sleeve defining a cavity with an electric resistance heater wound on said sleeve about said cavity, a heat insulator positioned about said heater and comprising a vacuum bottle with an open top for receiving said sleeve and heater, a metal heat sink removably positioned within said cavity and having a central opening for receiving the temperature probe, first and second temperature sensing elements mounted in said well, a control circuit for energizing said heater for maintaining the temperature of the heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point, and means for removably mounting each of said wells in said housing and spaced from the housing wall; a readout circuit for indicating the temperatures of said heat sinks; and means for selectively connecting each of said second temperature sensing elements as inputs to said readout circuit.

Claim 9

In a system for providing a plurality of accurate temperatures for calibration of a temperature probe, the combination of: a housing; a plurality of wells, each of said wells having a metal sleeve defining a cavity with an electric resistance heater wound on said sleeve about said cavity, a heat insulator positioned about said heater and comprising a vacuum bottle with an open top for receiving said sleeve and heater, a metal heat sink removably positioned within said cavity and having a central opening for receiving the temperature probe, first and second temperature sensing elements mounted in said well, a control circuit for energizing said heater for maintaining the temperature of the heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point, and means for removably mounting each of said wells in said housing and spaced from the housing wall; a readout circuit for indicating the temperatures of said heat sinks; and means for selectively connecting each of said second temperature sensing elements as inputs to said readout circuit.

Claim 10

In a system for providing an accurate temperature for calibration of a temperature probe, the combination of: a well having a metal sleeve defining a cavity with an electric resistance heater wound on said sleeve about said cavity and a heat insulator positioned about said heater and including a vacuum bottle with an open top for receiving said sleeve and heater; a metal heat sink removably positioned within said cavity and having a central opening for receiving the temperature probe; a first temperature sensing element mounted in said well; and a control circuit for energizing said heater for maintaining the temperature of said heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point.

Claim 11

In a system for providing an accurate temperature for calibration of a temperature probe, the combination of: a well having a metal sleeve defining a cavity with an electric resistance heater wound on said sleeve about said cavity and a heat insulator positioned about said heater and including a vacuum bottle with an open top for receiving said sleeve and heater; a metal heat sink removably positioned within said cavity and having a central opening for receiving the temperature probe; a first temperature sensing element mounted in said well; and a control circuit for energizing said heater for maintaining the temperature of said heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point.

Claim 12

In a system for providing an accurate temperature for calibration of a temperature probe, the combination of: a well having a cavity with an electric resistance heater positioned about said cavity and a heat insulator positioned about said heater; a metal heat sink, removably positioned within said cavity and having a central opening for receiving the temperature probe; a first temperature sensing element mounted in said well; a control circuit for energizing said heater for maintaining the temperature of said heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point; a second temperature sensing element mounted in said well, with the impedance thereof varying nonlinearly as a first function of a temperature; and a readout circuit for indicating the temperature of said heat sink and having said second temperature sensing element connected thereto as an input, said readout circuit including a linear meter for indicating a segment of the temperature scale; a rectifier element having an impedance varying nonlinearly as a second function of voltage, with said second function corresponding to said first function; first signal amplifier means with a preset gain and having an input and an output; second temperature reference amplifier means having a preset output maintained substantially constant with varying load; means for presetting the output of said second amplifier means to a temperature value to provide an output defining the low end of said meter segment; circuit means for connecting said second temperature sensing element to said first amplifier means input; circuit means for connecting said meter and said rectifier element in series between thE outputs of said first and second amplifier means; and circuit means for connecting a feedback signal from the meter-rectifier element junction to the input of said first amplifier means.

Claim 13

In a system for providing an accurate temperature for calibration of a temperature probe, the combination of: a well having a cavity with an electric resistance heater positioned about said cavity and a heat insulator positioned about said heater; a metal heat sink, removably positioned within said cavity and having a central opening for receiving the temperature probe; a first temperature sensing element mounted in said well; a control circuit for energizing said heater for maintaining the temperature of said heat sink substantially constant at a set point and having said first temperature sensing element connected thereto as an input, said control circuit including means for varying said set point; a second temperature sensing element mounted in said well, with the impedance thereof varying nonlinearly as a first function of a temperature; and a readout circuit for indicating the temperature of said heat sink and having said second temperature sensing element connected thereto as an input, said readout circuit including a linear meter for indicating a segment of the temperature scale; a rectifier element having an impedance varying nonlinearly as a second function of voltage, with said second function corresponding to said first function; first signal amplifier means with a preset gain and having an input and an output; second temperature reference amplifier means having a preset output maintained substantially constant with varying load; means for presetting the output of said second amplifier means to a temperature value to provide an output defining the low end of said meter segment; circuit means for connecting said second temperature sensing element to said first amplifier means input; circuit means for connecting said meter and said rectifier element in series between thE outputs of said first and second amplifier means; and circuit means for connecting a feedback signal from the meter-rectifier element junction to the input of said first amplifier means.

Claim 14

A system as defined in claim 1 in which said well includes a metal sleeve defining said cavity with said electric resistance heater wound on said sleeve, and including movable cover means of thermal insulating material carried on said well at the top thereof and overlying said heat sink, with an opening for passage of the temperature probe.