| 摘要 |
1,202,985. Valves. GENERAL GAS LIGHT CO. 5 March, 1968 [8 March, 1967; 12 May, 1967], No. 10710/68. Heading F2V. [Also in Divisions G4-G6] A pneumatic device is responsive to a preset number of pulses to produce an output pulse and restore itself. A selector knob 32, Fig. 2, is pulled out and turned together with transverse rod 39 to indicate the preset number on a dial, the knob being then located by engagement of a fixed pin 37 with one of a series of recesses 36. Movement of the rod 39 carries along an upstanding rod 43 on a ratchet wheel 27, against the action of a torsion spring 46. Pneumatic pressure applied to inlet port 148 presses a detent pawl 97 against ratchet wheel 27. The first pulse also operates driving pawl 67 which turns wheel 27, detent 97 being cammed backwards until it snaps over the next tooth. The wheel 27 is advanced stepwise until at the preset count its pin 48 drives slide 102 to the left, so moving valve 127, Fig. 5, to the left. Pressure air is thereby fed to port 152 to operate an external load. At the same time pressure is fed through passageway 157 into chamber 92 to release the detent 97. When the pressure in the system falls sufficiently for driving pawl 67 to return under spring action the wheel 27 is restored by torsion spring 46, and the system is ready to repeat the count. |
