Patent GB-467505-A (GB)
Title: Improvements in or relating to regulators
IPC: G05B11/01
Filed: 1935-12-17
Abstract: 467,505. Actuation of switches. ELECTROFLO METERS CO., Ltd. (Republic Flow Meters Inc.) Dec. 17, 1935, No. 34979. [Class 38 (v)] [Also in Group XXXV] A regulating apparatus for controlling for example, the pressure of fluid in.a pipe 10 by means of a valve 12, comprises a piston 20 connected to the valve 12 the supply of pressure fluid to which is controlled by a pilot valve 28. The pilot valve 28 is actuated through reduction gearing 52 by a reversible electric motor 50 to supply the pressure fluid to one side or the other of piston 20, the resulting movement of this piston actuating the valve 12 and also restoring the pilot valve to its original position by means of a floating lever 24 which is connected to the piston 20, the pilot valve, and the actuating member 40 of the motor gearing. The duration and direction of operation of the electric motor 50 is controlled by the pressure in pipe 10 acting on a diaphragm 98 which moves a normally balanced lever 84 which carries a switch contact 142 arranged between two contacts 160, 162 on a lever 158. The lever 158 is attached to a dashpot piston 224 at one end and is continuously oscillated by a cam 210 on a motor-driven shaft 212 which also drives a cam 216 which opens a switch 174 every half-revolution, this switch being in series with the two contacts 160, 162. When the lever 84 with the contact 142 is in the normal balanced position the lever 158 oscillates freely about the dashpot end without the contacts 160, 162 touching the contact 142. If the lever 84 is moved however, due to a change in the pressure in the pipe 10, one or other of the contacts 160, 162 engages with the contact 142 which actuates one or other of two solenoids 170, 192 which closes one of the circuits of the motor 50 and the circuit of another solenoid 250. This solenoid 250 actuates a brake 252 acting on a rod 254 to hold the right-hand end of the lever 158 at rest and at the same time opens a passage 230 between the two sides of the dashpot piston 224 and allows movement of the piston 224 and the left-hand end of lever 158 under the action of the cam 210. This displacement of the dashpot piston and at the same time the operation of the motor 50 can only take place for a period up to a half-revolution of the shaft 212 since the switch 174 is then opened and the circuits of the motor 50 and the brake solenoid 250 are broken. The dashpot passage 230 is also closed and the lever 158 resumes its oscillatory movement about the dashpot end but about a different mean position since the dashpot has been displaced, this new position being such that neither of the contacts 160, 162 engage the contact 142 even though the latter is displaced from its normal position. As the pressure in the pipe 10 returns to normal, as a result of the correction applied to the valve 12 through the servomotor 20 under control of the electric motor 50, the lever 84 gradually returns to its normal position and centralizing springs 218, 220 return the dashpot piston and the left-hand end of the lever 158 to the normal position at the same time. For any further correction required the operation described above is repeated.