Temperature sensor having rate of change of temperature sensing means

1,081,213. Fluid-pressure servomotor systems. BENDIX CORPORATION. March 1, 1966 [March 17, 1965], No. 9009/66. Heading G3P. A temperature responsive control mechanism comprises a coiled tube 16, in the path of the temperature to be sensed, containing helium which opens into a chamber 22 bounded by a diaphragm 26. A capillary tube 34 connects the chamber 22 to a chamber 24 on the opposite side of the diaphragm 26, the chamber 24 being bounded by a second smaller diaphragm 30. The two diaphragms are connected by a rod 32 and act through a member 46 on a lever 38, the chamber 28 on the opposite side of the diaphragm 30 being evacuated. Changes in temperature first act on the larger diaphragm 26 until the pressure on the opposite side is balanced by the capillary tube when the pressure acts on the smaller diaphragm 30 thus providing a derivative action. The lever 38 controls a leak valve 48 to provide an output signal pressure on a bellows 84, a feedback bellows 68 being provided to act on the lever. A damping bellows 54 with a restriction 58 also acts on the lever.