Patent GB-1154469-A (GB)
Title: Improvements in or relating to Supervisory Systems
IPC: F15C1/00
Filed: 1966-08-22
Abstract: 1,154,469. Fluid, logic circuits. HONEYWELL Inc. Aug.22, 1966 [Aug.23, 1965], No.37615/66. Heading F1P. [Also in Division G3] In a plant supervisory system pure fluidswitches control indicators and shut down of the plant in response to one or more of the parameters reaching an excessive value. As described, the system controls the fuel valve 22 of a heat engine driving a compressor and the fuel valve is closed to shut down the plant in the event of an excessive full in oil pressure or an excessive vibration of the engine. The system is supplied with fluid at 26 leading to a high pressure manifold 30, a medium pressure manifold 33 and a low pressure manifold 36, these pressures being controlled by regulators 27, 32 and 35. Under normal condition, the oil pressure sensor 14 closes the connection between conduit 15 and exhaust 16 and the vibration sensor 17 closes the connection between conduit 20 and exhaust 21 thus pressure in manifold 33 is fed through orifice 40, conduit 55 and orifice 54 to control port 52 of switch 45 having a preferred outlet 50 and through orifice 43, conduit 67 and orifice 66 to the control port 64 of switch 46 which has a preferred outlet 62. Since the control ports 53, 65 of switches 45, 46 are fed from the low pressure manifold 36, under normal condition the switches discharge through outlets 51, 63 and there is no pressure signal fed to the control ports 140 or 141 of a switch 134 having a preferred outlet 136 nor is pressure fed to the control ports 80 or 107 of switches 74, 130. Nozzles 47, 61 of switches 45, 46 are fed from conduit 132 which under normal conditions receives the outlet of switch 121 which is supplied from manifold 33. The switches 74, 130 are fed from manifold 36 and normally discharge through outlets 76, 105 to move indicator pistons of indicators 72, 73, 101, 102 outwards, the indicators having transparent ends. The fuel valve 22 is controlled by a pilot valve 162 which is actuated to open the valve by pressure in conduit 171 which is controlled by a switch 163 having a preferred outlet 165. Assume that the oil pressure falls to an excessively low valve, the sensor 14 connects conduit 15 to exhaust 16 and consequently the pressure at control port 52 falls and the output of switch 45 changes to outlet 50. A control signal is now fed to control port 140 of switch 134 and control port 107 of switch 130 thus moving the pistons of indicators 101, 102 inwards. The effect on switch 134 is to change its output to 137 and flow through conduit 142 to change the output of switch 121 to 124 thus cutting off the supply of power fluid to switches 45, 46 so that the indicators 72, 73 cannot be actuated by subsequent events. The output 124 of switch 121 now acts to change the output of switch 163 and 166 and the supply to the pilot valve 162 ceases thus causing the fuel valve 22 to close and shut down the plant. The output of switch 121 also actuates indicators 143, 144 which may be a remote indication of plant shut down. In the event of excessive vibration, the system acts in a similar manner to actuate indicators 72, 73, 143, 144. The system also includes valves for re-set, start, and test. The initiation of test provides that the system may be checked without causing shut down of the plant. During the test period, the system cannot function in response to the parameter. To test the system, a valve 262 is opened to fill a delay volume 261 with sufficient fluid to allow testing of the system. This volume feeds control port 252 to switch the output from 250 to 251. The loss of pressure at 250 actuates a switch 240 and indicator 232. The rise in pressure at 251 acts on the control port 170 of switch to maintain the output of switch 163 at 165 and hence conduit 171 so that the pilot valve 162 of the fuel valve keeps this fuel valve open while the test is made. The test is now made by opening test valve 267 or 274 which operates the indicators as above but does not shut the fuel valve due to the pressure acting on control port 170 of switch 163. At the end of the test if the volume 261 has not exhausted, valve 264 may be opened to achieve this. The system is re-set to automatic control by opening valve 87.