Patent GB-517391-A (GB)
Title: New and improved thermostatic regulator
IPC: G05D23/12
Filed: 1938-07-26
Abstract: 517,391. Thermostats. WILCOLATOR CO. July 26, 1938, No. 22197. Convention date, June 23, 1938. [Class 135] [Also in Groups XIII, XXIV and XXXVII] A thermally-actuated valve or electric switch for controlling the temperature in an appliance has the temperature in the appliance indicated by a pointer co-operating with the scale of temperatures used for indicating the setting of the temperature adjusting means. In the form shown in the Figure, a lift valve member 29 co-operating with a pair of concentric knifeedged seats is actuated by a tappet 48 loaded by a spring 72 and adjustably screwed to a spindle 46 passing loosely through a central aperture in the valve member. The spindle 46 carries a cross-head 45 which has slotted ends adapted to receive the reduced ends of a corrugate bimetallic strip 43 bearing at its centre part on the spindle 46. The slots also receive the reduced. ends of a member 42 having a central aperture engaging the reduced end of a spindle 40. This spindle has a head held by a spring 40' against the closed end of a bellows 33. The bellows is housed in a chamber 34 connected by a capillary tube with a thermal feeler so that variations of temperature cause movement of the bellows which movement is transmitted to the tappet through the bimetallic strip which compensates for local temperature changes. A hollow setting spindle 50 rotatably mounted in the casing is slotted at one end to engage lugs 48' on the tappet and at the other has a series of peripheral grooves 52. A washer 53 having a key-hole slot is passed over the end of the spindle and then moved laterally into one or other of the slots, a key 54 on the washer at the same time being moved into engagement with a longitudinal groove in the spindle. A knob carrying member 56 and a stop carrying member 60 are clamped about the washer 53. The adjusting knob 63 which has a window 66 is attached to an arm 57 on the member 56 by a screw 64 and is provided with a series of temperature graduations adapted to co-operate with a fixed index. The temperature indicator comprises a pointer on a head 79 frictionally mounted on a spindle 71 adapted to co-operate with the scale on the setting dial. The spindle 71 which is held against the end of the spindle 46 by a torsion spring 74 has a screw-thread of slightly less pitch than that of the thread on the spindle 46. This thread co-operates with a pin 73 screwed into a fitting itself screwed in the hollow setting spindle. A modification is described in which the invention is applied to a thermo-electric regulator. In this form the adjustable abutment 48 which engages a switch actuating lever is formed integrally with a threaded spindle adapted to co-operate with a threaded socket mounted on a pin secured to the thermal bellows. The socket is slotted to engage projections on a fixed washer whereby it is held against rotation. The stop washer 60 is also provided with a cam surface adapted to act through a sliding rod and spring arm on the switch actuating mechanism to open the switch when the adjusting handle is turned to the " off position.