Patent GB-494146-A (GB)
Title: Improvements in or relating to actuating systems for controls on aircraft
IPC: B64C13/00
Filed: 1937-01-18
Abstract: 494,146. Fluid-pressure servomotor-control systems. SIEMENS APPARATE UND MASCHINEN GES. Jan. 18, 1937, No. 1523. Convention date, Jan. 16, 1936. [Class 135] [Also in Group XXXIII] As shown, a regulator e, to control admission of fluid to a cylinder i, is inserted in the rod b, c. The rod c and piston-rod k<1> are pivoted to a lever t which is further pivoted to the control rod s of a regulator e<2> for a cylinder i<2>, the piston j<2> of which is pivoted to the rod c. The lever t is connected with the control surface p through a rod y. The rod c may be connected to flap-operating gear w. The regulator in one form comprises a cylinder 10, Fig. 2, with conduits 4, 5 adapted to co-operate with a recess in the piston 2. Pipes g, h connect the regulator to the operating-cylinder and pipes l, o connect the regulator respectively, to the fluid pressure supply and to exhaust. Setscrews 6, 7 permit of control of relative movement between the piston and cylinder. On movement of the piston 2, one side of the piston is connected to supply and the other to exhaust, movement of the operating-piston j<1> takes place until the pressure on the supply side of the piston 2 builds up to such an extent as to force the piston 2 to its central position and thus prevent further supply or exhaust of fluid. Thus, the ratio of the force exerted by the power device is determined by the ratio between the areas of the pistons in the cylinder i and in the regulator. In a modification, the regulator comprises a grooved piston which is actuated manually to connect the appropriate side of the operating-piston to supply or exhaust. In a further modification, additional helical grooves are provided in the surface of a rotary piston. The invention may be applied to, e.g. retractable undercarriages. A pressure accumulator may be incorporated in the pressure pipe. Means may be provided for isolating or cutting out the power device in the event of damage to the system. An auxiliary source of power may be provided and the device may be used in conjunction with an automatic pilot. The Specification as open to inspection under Sect. 91 comprises also a hand lever a, Fig. 1 (Cancelled), movement of which actuates a control surface p and operates a regulator e, the relatively movable parts of which are connected to rods b, c. The regulator e controls the supply of fluid under pressure to a cylinder i, the piston j of which is pivoted to the rod c. The fluid under pressure is supplied by a pump m connected to an accumulator n. The regulator e may comprise bodies of variable electrical resistance. A discharge pipe o leads from the regulator back to the pump. In modifications, the piston is connected to the hand lever through a sleeve axially adjustable along the lever, in which case the control surface may be overbalanced; or the piston is connected to the rod c and the cylinder is adjustably connected to the hand lever and in this case a cam may be inserted in the connection between the hand lever and the regulator. In a further form, the regulator is fixed and is actuated through a rod s, Fig. 5 (Cancelled), through a link b and a lever t, which is connected by a link c to the control surface p. The piston j is connected to the hand lever a. In a modification of this form, the cylinder and regulator are fixed adjacent each other, the piston being connected to a point on the lever t. In order to vary the proportion of power exerted by the power device, the point on the lever t may be varied by a cam slot. The point at which the regulator is connected to the lever t may be adjustable. A spring may act on the pivotal connection between the regulator rod s and the lever t to bias the regulator and the force may be made dependent upon air-speed. Alternatively, the pivot may be adjusted along the lever t by a wind vane. In a further modification, the regulator is mounted on the handle of the hand lever, the piston being connected to the hand lever ; or the piston is mounted on the casing of the regulator ; or the regulator is connected to and forms the pivot of the hand lever, its casing being fixed and connected to the cylinder, the piston of which is connected to a rod connecting the hand lever directly to the control surface. In a further modification, a connecting-pipe g, Fig. 12 (Cancelled), communicates with the power cylinder and branches from a fluid circulation system, e.g. lubricating-system l, o, into which is inserted a hose connector 8 adapted to be throttled by pressure from an extension on a piston 2 connected to the hand control. Throttling causes liquid to flow into the pipe g until the pressure accumulates to equal the pressure on the projection. A regulator similar to that described with reference to Fig. 12 (Cancelled) is shown in Fig. 14 (Cancelled) applied to a landing-flap control. The effect of the projection on the piston is obtained by a cap v and a flexible hose e which passes through the hand lever a. As shown in Fig. 19a (Cancelled), an additional regulator e" is provided. The regulator e<11> comprises a vertically disposed mass 2<11>, Fig. 19b (Cancelled), which can move under the action of centrifugal force against the action of a spring g and between adjustable abutments 6<11>, 7<11> to close the pipes o, l and render the regulator e ineffective. This will prevent overstraining due to too steep a dive or climb. This construction is described in Specification 494,291, [Group XXIX]. In Fig. 20 (Cancelled), the system includes a hand lever a, a power transmitter i', j<1>, and a power receiver i<2>, j<2> connected to an elevator. The piston j' forms the casing of the regulator e. On movement of the lever a the piston j<1> causes an equal movement of the piston j<2> which through connections 12, 13 moves the regulator rod so that this is not actuated except to compensate for leakage of fluid. This subject-matter does not appear in the Specification as accepted.