Patent GB-569955-A (GB)
Title: Improvements in or relating to means for controlling the operation of engine coolingsystems
IPC: F01P7/12
Filed: 1943-09-08
Abstract: 569,955. Automatic control systems for cooling aircraft engines. HURST, W. F. F. MARTIN-, and BRITISH THERMOSTAT CO., Ltd. Sept. 8, 1943, No. 14721. [Class 38 (iv)] Temperature.-A component of an aircraft or engine thereof, the position of which varies with flight conditions, e.g. throttle setting or . engine speed, actuates a selector switch cooperating with the thermostatically controlled inching mechanism of cooler flaps of a cooling system or of an air-cooled engine so that a range of movement of the flaps or a temperature range appropriate to the prevailing flight condition is obtained. Fig. 6 shows contacts 15a, 15b, 15c co-operating respectively with separate pairs of contacts 20a, 21a and operated by means responsive to the temperature of, or adjacent to, the engine, or of the coolant, whereby relays 72 are selectively operated to drive a motor . 74 in a sense to restore heat balance upon a change in temperature. The contacts 15a ... c are rendered selectively operable, to determine the range of temperature variation or of movement of the flaps operated by the motor, by a switch 70 operated by the component aforesaid. A cam also driven by the motor opens the switch 15 after a short movement and produces an inching effect, but the relays 72 are otherwise maintained energized by holding circuits through switches 75 and a switch 66 operated at regular intervals in the range of movement of the flaps to release the relays. Limit switches 46, 47, in relay and field circuits respectively, are operated also by the motor and are adjustable to determine the limits of flap movement. A switch 76 may be operated manually to drive the flaps to fullyopen position for testing. A switch 68 may be moved from the " automatic " position shown to render operative a switch 53 which is manually adjustable to determine a compromise position to which the flaps are driven when the switch 68 has been moved. The switch 68 also has an " off " position interrupting all circuits from the battery 69. In a modification, in which a pneumatic jack or equivalent means operates the flaps, the relays 72 control pairs of pressure and exhaust valves and the switches 46, 47, 75 and 66 are omitted. Fig. 1 shows the adjustable limit switches 46, 47 actuated by a member 42 driven through lost motion from a, shaft 39 coupled to a shaft 30 which carries a crank 31 operating the flaps. The shaft 30 also carries the inching or followup cam and a toothed member 65 engaging a follower member 67 which operates the switch 66. This Figure also shows the switch 53 which may be turned relative to the shaft 39. Figs. 4 and 5 show a thermally responsive bellows 5 and a spring-controlled bellows 6 which may correct for ambient temperature and pressure conditions. These act in opposition on a member 12 carrying the contacts 15a, ... c to rock it on an axis 11. The contacts 20a ... c and 21a ... c are carried on a member 17 also rocking on the axis 11 and controlled by the inching cam 29 on the shaft 30 so that its position varies with the position of the flaps. The cam consists of a cylinder bored longitudinally at an angle to its axis and by adjustment of the cam along the shaft 30 or of the follower 28 along rods 19 parallel to this shaft and carried by the member 17, the range of movement of the flaps may be adjusted. The six contacts 20 and 2] are each independently adjustable by screws 24. The invention also operates to restore the flaps to any position from which they may have been moved by a change in airload on the flaps.