GB1423365A - Fuel control apparatus for a gas turbine engine reheat system - Google Patents

Abstract

1423365 Gas turbine engine re-heat fuel systems LUCAS INDUSTRIES Ltd 26 March 1973 [21 June 1972] 33843/75 Divided out of 1423364 Heading F1J The invention relates to a fuel control apparatus for a gas turbine engine re-heat system which comprises a pump 10, a throttle valve 11 responsive to a first servo-pressure signal PS 1 for controlling the delivery pressure PP of the pump, a first variable metering orifice (in the embodiment there are three, 17, 18, 19) for controlling fuel flow from the pump to a re-heat burner (20, 21, 22), means for driving the pump at a speed proportional to engine speed, and a servo-pressure control arrangement 81, Fig. 3 responsive to engine speed, by means of governor 87, and to the pressure drop PP-DP1 across the first metering orifice 17, for varying the said first servo-pressure signal PS1. The arrangement 81 comprises three valve spools 86, 101, 111, the fuel pressure DPI being applied through line 80 so as to act on the left-hand end of the valve spools. The governor 87 also acts against the left-hand end of the valve spool 86. Fuel at pump delivery pressure PP acts against the right-hand end of valve spool 86. The valve spool 86 is connected by a spring means 88 to a further spool 89. Pump pressure PP is also applied to an internal passage 103 and the servopressure PS1 is derived therefrom through passage 94 in dependence on the axial position of the valve spool 86. The valve spools 101, 111 are respectively dependent on the difference in pressure DPI and DP2 and DPI and DP3. Servo-pressures S2 and S3 are derived from the spool valves 100 and 110 respectively and are communicated to the throttle valves 76, 78 of the metering assembly 14.