Patent GB-612425-A (GB)
Title: Improvements in control mechanisms
IPC: F02C9/00
Filed: 1945-10-29
Abstract: 612,425. Escapement mechanisms. POWER JETS (RESEARCH & DEVELOPMENT), Ltd., and BRAME, E. Oct. 29, 1945, No. 28599. [Class 80 (iv)] [Also in Groups XXVI, XXVII and XXXIV] The maximum rate at which lost motion between the driving and driven members of an engine throttle control transmission can be taken up by spring means is determined by an escapement acting in accordance with an inherent function it possesses and/or in accordance with variations in a selected function or functions of the operation of the machine to which the throttle control is applied. As shown applied to the throttle control of an aircraft engine, a throttle lever 1, Fig. 1, operates a coaxially pivoted quadrant 9 in the throttle opening direction through a spring 16, the maximum rate of movement of the quadrant being determined by a sliding-sleeve speed governor 27 on a shaft 19 geared through a one-way ratchet 18 to a rack 10 on the quadrant. The governor sleeve coacts with a pivoted stop 30 which is adjustable, directly or through servo mechanism, to vary the maximum rate of driven movement allowable, according to factors such as air speed, altitude, temperature, acceleration or combinations of these. Throttle closing is effected at any desired rate through coacting abutments 8, 14, the ratchet 18 overrunning. In a modification, driving and driven pinions 39, 64, Fig. 2, are connected by a gear pair 38, 52, a double helical spring 53, a collar 42 and a second gear pair 43, 61, the lost motion being limited by a pin 59 working in a slot (not shown) in the hub of the gear 52. A second gear train 72, 66 in driving connection with the gear 61 imparts motion to a large gear 74 having four speed governors arranged round its periphery. Each governor comprises two resilient arms 100, Fig. 4, rotated through a worm 87; a worm-wheel 78 and a one-way coil clutch 86 from a pinion 77 meshing the gear 74. The arms 100 coact with an internally coned member 96 which can be rotated on a screwed boss 94 to vary the maximum driven rate, a locking tongue 98 which engages milling 99 on the outer surface of the member 96 being provided. In a further form a throttle lever 110, Fig. 5, is connected to its operating rod 126 by a lost-motion spring plunger 119 and a lever 124 whose remote end carries a pivoted roller 130 coacting with a controlling device comprising two flanged quadrants 136, 139. The quadrant 136 is fixed and carries in its flange radially movable balls 138, whilst the quadrant 139 is rotatable about the pivot 125 of the lever 124 under the control of a walking beam 146, and has a stepped flange, the thinner portion 140 of which allows the balls 138 to move outward far enough for the roller 130 to pass over them from left to right and the thicker portion 142 of which holds the balls inwards and obstructs the roller. The second pivot 148 of the beam 146 is connected to a duplicated sliding-sleeve engine-driven speed governor 155, and the third pivot 162 provides a secondary adjustment, and may be connected to a device responsive to any of the factors mentioned above alone or in combination, but is shown as controlled by a double bellows 164, 165 connected to static and pilot pressure tubes respectively. When the lever 110 is operated to open the throttle the roller 130 moves to the right under the action of the spring plunger 119 until it meets the first inwardly protruding ball when it is obstructed until the increased engine speed resulting from the initial throttle movement moves the quadrant 139 to the right through the governor 155 and allows the obstructing ball to move clear. A follow-up action thus proceeds at a definite rate depending only on the characteristics of the mechanism and the movement of the pivot 162. The roller 130 can deflect to the right against a spring 133 to follow completely a throttleclosing movement even if the engine speed has meanwhile dropped independently and a ball to the left of the roller is protruding inwardly.