GB844181A - An improved helicopter prime mover speed control - Google Patents

Abstract

844,181. Controlling helicopter engines. CURTISS-WRIGHT CORPORATION. Oct. 21, 1957, No. 20948/59. Divided out of 844,180. Class 4. The rotor of a helicopter is driven by a prime mover, the throttle of which is connectable by selector means either to a manual control element or to a governor. In the Fig. the pilots' collective pitch lever 16 has a twist grip 17a which is rotatable, and engages a spline 100 on the lever 16 to rotate with the lever which is connected through bevel gears 76, 77 and link 18 to the throttle (not shown). Twist grip 17a is slidable between upward and downward positions on lever 16, defined by two detents 82, 84, and is connected by a cable 79 to a manual/automatic changeover lever 58 on the governor mechanism 20. In the upward position (detent 84 engaged), lever 58 is placed by cable 79 in one position, whereby the governor output signal appears on an output lever 19 connected to control link 18, the throttle, and the twist grip. In the downward position (detent 82 engaged) lever 58 is moved to another position, whereby the governor output signal is removed from lever 19 and link 18, the twist grip being adjusted manually to control the throttle. The twist grip may be moved beyond the normal upward position by compressing a spring 88. The grip then leaves spline 100, and is connected to a rod 92 through dog clutch members 86, 90. Rotation of the grip then rotates bevelgears 94, 95 and moves link 98 and lever 54a, which sets the datum speed at which the governor maintains the engine. In a modification, Fig. 5 (not shown), the governor datum setting arrangement 86, 88, 90, 92, 94, 98, and 54a is omitted, and the manual /automatic changeover lever 58 acts on the governor mechanism so that on changeover to automatic throttle control, the governor maintains the engine speed at that prevailing when automatic control was initiated. In an electrical version of this embodiment, Fig. 2 (not shown) the changeover lever 58 is actuated by a'solenoid controlled by a push button switch on the twist grip. A further switch is operable by the governor so that if overspeeding occurs, during manual control, the solenoid is actuated to select governor control. A master switch can, however, be operated by the pilot to disable the solenoid and maintain manual control at all times. The governor mechansim 20 is described in Specification 844,180 [Group XXVI].