GB1284750A - Improvements in jet engines for aircraft - Google Patents

Abstract

1284750 Deflecting propulsion jets H M HOBSON Ltd 13 Nov 1970 [18 Nov 1969 28 Nov 1969] 56447/69 and 58400/69 Heading B7G [Also in Division F2] A thrust reversal system for an aircraft jet engine comprises a pair of thrust reverser buckets 10 movable via an air motor 14 operable by the pilot between a stowed and a deployed position and a mechanism for automatically decelerating the motor as the buckets approach both the stowed and the deployed positions. Bucket actuators 13 are interconnected and driven by encased flexible shafts from the air motor and impart bucket motion through screwshafts 20, links 11, 27 and brackets 12 from a ball servo-actuator comprising a recirculating ball nut motor 25. In operation a pilot-operated selector valve 69, Fig. 3, is moved left under pilot control and compressed air from a compressor of the engine enters the system through solenoid operated combined shut-off and pressure regulating valve 38 so initiating the opening cycle through servomotor 73 which removes bucket locking plunger 76 from a recess 77. Air behind piston 74 then actuates a further servo whose piston 81 operates a directional control valve 83. Actuator 84 associated with this servo then operates interlock valve 92 to bleed valves 119, 120 and dump valves 99, 100 to open snubber valve 88 and brake 89 through their respective servos. Compressed air from passage 68 then passes through 85, the motor 14 to exhaust 87 so driving the buckets. Bucket motion, speed controlled by valve 112, then actuates cam-operated vent valves 41, 42 to bleed air from valves 99, 100 and so close the snubber and apply the brake. To return the buckets for stowage, the pilot de-energizes solenoid 47 of valve 38, the valve being retained open by air from passages 121, 122 until the locking plunger is again engaged in recess 77. Valve 69 is then moved right, connecting servomotor 73 to exhaust and allowing air through passages 70, 124 to move valve 83 and so the motor 14 in the opposite direction. Operation of 83 again actuates interlock valve 92 to disengage brake 89 and open snubber 88. Near the stow position, cam-operated vent valves 102, 103 are again opened, causing bucket deceleration to the stow position where the buckets are looked. The system may be modified by introducing feedback mechanisms, connected to an electrical control valve of the air motor or to the snubber valve, in place of the cam-operated valves. In such cases the snubber valve and/or brake may be omitted.