GB1331141A - Pneumatic timing device for time delay relays - Google Patents

Abstract

1331141 Pneumatic timing devices BROOK. HIRST IGRANIC Ltd 19 April 1971 [18 Feb 1970] 20311/71 Heading F2S [Also in Divisions G3 and H1] A pneumatic timing device 2 comprises an expansible chamber 56, and means for controlling the rate at which air enters it comprising a valve member 64, Fig. 3, having a groove 72 formed in its external surface and having a passageway 74 communicating with the groove and with the chamber, and means 90 operable to progressively dispose a sealing means 80 over the groove to form a timing passage of increasing length "L" to decrease the rate at which air may pass therethrough to enter the chamber. The V-groove 72 is rolled into the body 64, leaving slight ridges on the surface. Rotation of a dial 84 carrying the roller 90 adjusts the distance "L". The device is combined with a solenoid 4 and a snap-action switch 8 as in Specification 886,253. The plunger 12 of the switch 8 is shown depressed by a lever 14 straddling a cup 18 connected to a plunger 20 secured to a washer 22 moulded into a diaphragm 24. The cup 18 is urged downwardly by a spring 44 and contains a spring to bias downwardly a further plunger 28 to engage an armature 36. The armature 36 can be retracted against a spring 42 by energizing a coil 32. The coil 32 is retained by a spring 34. In operation, when the solenoid 32 is actuated, the armature 36 is retracted away from the plunger 28. The spring 44 then moves the cup 18 downwardly at a rate controlled by the flow of air through the groove 72 which allows the diaphragm 24 to move until the lever 14 releases the switch 8. When the solenoid is released, air flows round the upper surface of the diaphragm to escape through the passages 58, 60, as in USA Specification 3,040,842.