GB617911A - Improvements relating to apparatus for controlling the distribution of fuel in aircraft - Google Patents

Abstract

617,911. Automatic control systems. SMITH, S. J. May 16, 1946, No. 14778. [Class 38 (iv)] A system for controlling the volume of liquid in each of two tanks, particularly the distribution of fuel in the tanks of an aircraft, comprises a condenser, whose capacity is proportional to the volume of liquid in the tank, situated inside each tank, and means responsive to the ratio of these capacities for controlling means for varying the volume of liquid in the tanks in such a way as to maintain the ratio of these volumes at a desired value. As shown, the tanks A and B have condensers 1a, 1b respectively, both of these, together with reference condensers 5a, 5b, being energized from a common A.C. supply 8. The measuring system employed is the same for each tank and is described in Specification 560,872, [Group XXXVI]. The condenser currents are passed through the primary windings of transformers 3a, 6a and 3b, 6b, the secondaries of which feed rectifiers 4a, 7a and 4b, 7b, the output being applied to ratiometer instruments 2a, 2b, which are calibrated to indicate the volume of fuel in each tank. The secondary windings of the transformers are connected to the grids 9a, 9b of a twin diode amplifying valve 10, the anodes of which feed the grids of push-pull connected rectifying valves 14a, 14b, feeding the two opposing field windings 15 of a control motor 16. If the capacities of the tank condensers are -not in the correct ratio, the field balance is disturbed and the control motor, the armature of which is continuously energized, rotates and operates a slide 19 on a potential divider 20 which governs the relative speeds of a pair of motors 21a, 21b. These motors drive pumps 24a, 24b, withdrawing fuel from the tanks A, B, respectively and restore the desired volume ratio. The arrangement is made self-balancing by connecting the control motor to a slider 22 on a further potential divider which alters the screen grid potential of valves 14a, 14b, in such a sense as to offset the changes due to the valve 10. An over-riding manual control acting on the valve circuits may be provided.