GB1083660A - Pressure operated electric switching mechanism - Google Patents

Abstract

1,083,660. Thermal switches. RANCO Inc. Nov. 12, 1965 [Jan. 15, 1965], No. 48218/65. Heading H2B. A pressure-responsive control device, e.g. an adjustable thermostatic control for airconditioning or cooling apparatus, comprises a housing 11 mounted on the apparatus and containing a snap-action switch 13. Switch contacts 13a, 13c are actuated by toggle spring 17, 17b, part 17 having a portion extending through a tab 13d on arm 13b, said actuator 17 biasing the contacts apart. Contacts 13a, 13c are closed on depression of a button 18. An expansible capsule 20 depresses the button 18 through a resilient strip-like beam 21 opposing capsule expansion. The beam 21 is adjustably supported at one end by a screw 23 carried by an adjustable lever 24 (Fig. 1,) pivoted at 24b. The tension in the beam 21 is adjustable by a cam 26, rotatably mounted on the housing front wall 11h and engaging an arm 24c on lever 24. Cam 26 (Fig. 5), has a section (26e) which on engagement with arm 24c puts maximum force on beam 21 and hence provides an " off " position. Another section (26c) puts minimum stress on beam 21 and switch 13 is permanently closed. A further section (26d) provides a varying force and hence a range of operating temperatures. An auxiliary fan switch (30, Fig. 3), is provided comprising normally closed contacts (30a, 30b) which open when a rise (26f) on cam 26 engages a button (30e) on an arm 30c, at which time switch 13 is " off.". In a modification, (Figs. 6-8), the cam (53) is mounted on the housing top wall (lid) and the arm (51c) of the lever (51, Fig. 6) passes through an opening (21b) in the beam 21 to engage the cam (Fig. 7). When the switch is in the " off " position, arms 151d, 51e (Fig. 6) on the lever (51) engage lugs (57, Fig. 6) on the beam.