Methods and apparatus for temperature sensing
AssigneesBrissco Equipment Limited, David L. Melton
InventorsMartin W. Booker, David L. Melton
Life of this patent
Estimating the term…
Abstract
A temperature sensor has a flexible nylon tube connected by a fluid-tight coupling to a metal bellows within a metal housing. The interior of the tube and bellows is filled with a pressurized liquid whose critical temperature corresponds to a threshold temperature to be sensed. The pressurized liquid holds the bellows extended, holding an actuating piston back against the action of a spring. When the threshold temperature is reached, the liquid in the tube must boil and ruptures the tube, causing the bellows to collapse and the actuating piston to move. A projecting actuator then mechanically initiates a response such as the closing of a damper in an air-conditioning duct.
Claims32
A temperature sensor for determining when a sensed temperature reaches a threshold temperature, comprising
- a sensor element for exposure at a sensing location, said sensor element defining a burstable enclosure;
- a fluid contained in said burstable enclosure at a pressure so as to be at least substantially in liquid state, said fluid having a critical temperature corresponding to the threshold temperature of the sensor, and which thereby bursts the enclosure when the threshold temperature is reached, and
- a pressure-responsive component connected to the enclosure, for indicating a drop in pressure due to the bursting thereof.
A method of sensing a rise in temperature to a predetermined threshold value, at a sensing location, comprising
- positioning a fluid-filled enclosure at the sensing location, filling said enclosure with a fluid being at least substantially in liquid state and having a critical temperature corresponding to the predetermined threshold value;
- retaining the fluid in the enclosure until the predetermined threshold value is reached;
- bursting the enclosure by vaporising of the liquid at the predetermined threshold value, and
- detecting the consequent drop in pressure in the enclosure.
A temperature sensor element for detecting the reaching of a threshold temperature, comprising an enclosure and a fluid contained in the enclosure which can burst the enclosure by vaporising, wherein the improvement comprises employing a fluid selected to have a critical temperature corresponding substantially to the threshold temperature, and the enclosure having walls which withstand the pressure of the contained fluid substantially until said critical temperature is reached.
A temperature sensor comprising
- an elongate plastics tube for exposure at a sensing location;
- an expansible and contractible pressure-responsive element having a response movement direction, and connected to said tube in a fluid-tight manner such that the tube and pressure-responsive element together form an enclosure;
- a fluid contained in said enclosure at least substantially in liquid state, and under a pressure to maintain the pressure-responsive component in an expanded condition, said fluid having a critical temperature in the range 50.degree. C. to 200.degree. C. whereat vaporising thereof bursts the tube and the pressure-responsive component contracts in the response direction.
A damper installation for a service duct, comprising:
- (i) a duct damper;
- and
- means for moving the duct damper in the service duct between open and closed conditions;
- and
- (ii) a temperature sensor for determining when a temperature in the duct reaches a threshold temperature, said temperature sensor comprising
- (a) a sensor element comprising a rupturable elongate flexible plastic tube disposed in the cross-section of the service duct, and
- (b) a fluid contained in said tube at a pressure so as to be at least substantially in liquid state, said fluid having a critical temperature corresponding to the threshold temperature, and which thereby bursts the tube when the threshold temperature is reached;
- and
- (iii) a pressure-responsive component connected to the tube to detect loss of pressure therein owing to rupture thereof, and which responds to such loss of pressure by actuating said means for moving the duct damper so as to cause the duct damper to move to the closed condition.
Dependencies are inferred from the claim text.