Air temperature sensor

An apparatus for sensing the temperature of a gas, comprising:

• a temperature sensing device having a resistance which varies with temperature;
• a conditioning circuit mounted on a circuit board and being electrically connected to said temperature sensing device and adapted to measure a resistance across said temperature sensing device and produce an electrical signal which is insensitive to external resistive loading and which has a magnitude responsive to the sensed resistance;
• a tubular portion connected to said conditioning circuit, said temperature sensing device being encapsulated therein to prevent the gas from directly contacting temperature sensing device;
• a non-metallic housing encapsulating said tubular portion and said conditioning circuit, said housing forming an interior cavity and a front cavity, wherein said conditioning circuit is sealed within said interior cavity and said tubular portion is within said front cavity and said housing having a cage portion surrounding said tubular portion, said cage portion being adapted to protect and to provide gas flow to said tubular portion;
• and,
• wherein said housing includes a main body portion and a cap portion, the main body portion forming said interior cavity, said interior cavity being adapted to receive said circuit board, said cap portion being adapted for insertion into the interior cavity, said cap portion being bonded to said main body portion, which is adapted to hold said cap portion in place with sufficient compression to form a seal against moisture infiltration between said cap portion and said main body portion.

An apparatus for sensing the temperature of a gas, comprising:

• a thermistor having a resistance which varies with temperature;
• a conditioning circuit being electrically connected to said thermistor and adapted to measure a resistance across the thermistor and produce an electrical signal which is insensitive to external resistive loading and which has a magnitude responsive to the sensed resistance;
• a tubular portion connected to said conditioning circuit, said tubular portion including a rigid tube and a metallic tube, said thermistor being micro-encapsulated within said rigid tube, said rigid tube being encased by said metallic tube to prevent the gas from directly contacting said thermistor;
• and
• a non-metallic housing encapsulating said tubular portion and said conditioning circuit, said housing forming an interior cavity and a front cavity, wherein said conditioning circuit is sealed within said interior cavity and said tubular portion is within said front cavity and said housing having a cage portion surrounding said tubular portion, said cage portion being adapted to protect and to provide air flow to said tubular portion.