Patent GB-784107-A (GB)
Title: Improvements in or relating to thermostatic regulators for fluid fuel burning appliances
Inventor: WINSLOW ARNOLD ALGIRD
IPC: F23N5/02
Filed: 1955-08-25
Abstract: 784,107. Thermally actuated valves. ROBERTSHAW-FULTON CONTROLS CO. Aug. 25, 1955 [Jan. 4, 1955], No. 24498/55. Class 135. In a thermostatic fuel-regulator comprising a casing with an inlet 12 and an outlet each opening into a chamber 18, a valve seat 38 and a closure member 42 co-operating therewith, thermally - responsive means including a power device 32 movable axially relative to the seat 38, and levers 48, 50 for multiplying movement of the device 32 to move the member 42 from its open to its closed position, a spring 66 is provided to absorb further movement of the device 32 after the closure member has seated and also for coating with the levers to assist in biasing the closure member 42 to its open position. The graduated dial 26 is rotated to a desired setting, which rotation is transmitted by tongs 96, located in grooves 94 in the head of a shaft 24 coupled to the dial 26, to thereby screw the threaded part of the valve stem 44 into a tubular element 46 and cause movement of the member 42 away from its seat 38 under the bias of spring 66 and the action of the opposed levers 48, 50 with both a flange 70 on the element 46 and a washer 64. Fuel then flows from the inlet 12 to a domestic oven, for example, via the chamber 18 and the outlet. Upon the oven temperature, as sensed by a bulb 28, approaching that set on the dial 26 the power device 32 expands and forces a thrust element 76 towards the seat 38 so pivoting the levers 48 and 50 as to move the stem 44, member 42, element 46 and spring 66 in the direction of the seat 38. When the sensed temperature equals the selected temperature the member 42 engages the seat 38 and since the movement ratio between the member 42 and power device 32 is 2: 1 substantial throttling of the fuel is deferred until immediately before the member 42 is actually seated. Should the device 32 expand beyond the amount necessary to seat the member 42, the thrust element 76 continues to impart pivotal motion to the levers 48, 50 but the latter will now only compress the spring 66 to permit over-ride of the levers. When the sensed temperature falls below that set the power device contracts and enables the stem 44, member 42, element 46 and spring 66 to move towards the device under the reaction of the spring 66 and the operative connection of the levers 48, 50 with the washer 64 and flange 70. Movement of the dial 26 from one position to another varies the distance through which the member 42 must travel on to its seat 38 by rotating the stem relative to the element 46, which latter is prevented from rotating by a detent 86. A bimetal disc 84, responsive to ambient temperature, is inserted between the thrust element 76 and the power device 32 to maintain accurate calibration of the apparatus. The outer ends of the levers pivot in a split annular ring 52 which is sprung into the outer casing part 14 and has extending raised portions which are engaged by the end of the main casing 10 whilst it is being screwed to the part 14 in order to force the ring 52 further into its recess 54.