An auxiliary actuator (49) comprises a two stage telescopic hydraulic unit comprising first (59, 63) and second (56, 50) stage piston and cylinder actuators operating coaxially within an outer casing (50). A respective actuator is connected to a respective one of the strut (1) and bogie beam (4). Th
An auxiliary actuator (49) comprises a two stage telescopic hydraulic unit comprising first (59, 63) and second (56, 50) stage piston and cylinder actuators operating coaxially within an outer casing (50). A respective actuator is connected to a respective one of the strut (1) and bogie beam (4). The second stage actuator (56, 60) serves to control the tilt position of the bogie beam (4) relative to the strut (1). The second stage actuator (56. 60), when in the retracted position with the first stage actuator (59, 63) in the extended position, limits the length ol the auxiliary actuator (9) between its connections (62,67) to the strut (1) and bogie beam (4), so as to assume a predetermined intermediate length in which the bogie beam (4) is restrained to tilt about the auxiliary pivot (14) and thereby lengthens the landing gear during take-off.
대표청구항▼
1. An auxiliary actuator mechanism for semi-levered landing gear of an aircraft having a main shock absorber strut with upper and lower telescoping portions, with the upper portion connectable to the airframe, and a bogie beam extending fore and aft of the aircraft fuselage with at least one forward
1. An auxiliary actuator mechanism for semi-levered landing gear of an aircraft having a main shock absorber strut with upper and lower telescoping portions, with the upper portion connectable to the airframe, and a bogie beam extending fore and aft of the aircraft fuselage with at least one forward axle and wheel and one aft axle and wheel, and a main pivot between the forward and aft axle pivotally connected to the lower portion of the main shock absorber strut, the auxiliary actuator comprising a two stage telescopic hydraulic unit comprising an outer casing with a first stage piston and cylinder actuator having a first piston rod and a second stage piston and cylinder actuator having a second piston rod, the first and second stage actuators operating coaxially within the outer casing, one of the first and second stage actuators being pivotally connectable via an upper connector to the upper portion of the main shock absorber strut, and the other being pivotally connectable via a lower connector to the bogie beam at an auxiliary pivot; wherein the first stage actuator is adapted to dampen pivoting movements of the bogie beam about the main pivot and is operable to an extended position and the second stage actuator is operable between a retracted position and an extended position defined by respective end stops within the outer casing and serves to control the tilt position of the bogie beam relative to the main shock absorber strut, the second stage actuator, when in the retracted position with the first stage actuator in the extended position, limiting the length of the auxiliary actuator between the upper and lower connectors so as to assume a predetermined intermediate length in which the bogie beam is restrained to tilt about the auxiliary pivot and the landing gear is lengthened during take-off of the aircraft, and the second stage actuator, when in the extended position with the first stage actuator in the extended position, allowing the length of the auxiliary actuator between the upper and lower connectors to assume a predetermined maximum length in which the bogie beam is tilted about the main pivot to a stowing position for stowing the landing gear in the aircraft, wherein at least some of the piston rod of each of the first and second actuators extends out of the outer casing when in the extended position, and wherein movement of the second stage actuator from the retracted to the extended position causes pivoting of the bogie beam. 2. A semi-levered landing gear for an aircraft comprising: a main shock absorber strut with upper and lower telescoping portions, with the upper portion connectable to the airframe;a bogie beam to extend fore and aft of the airframe with at least one forward axle and one aft axle for respective forward and aft wheels and a main pivot between the forward and aft axle pivotally connected to the lower portion of the main shock absorber strut;and an auxiliary actuator mechanism as claimed in claim 1. 3. An auxiliary actuator as claimed in claim 1, wherein the first and second piston rods of the first and second stage actuators extend from a respective end of the casing and are arranged to be connected to a respective one of said upper and lower connectors. 4. A landing gear as claimed in claim 3 in which the first stage actuator comprises a first cylinder on which said second piston rod slides and seals coaxially, and a first piston head slidable in the first cylinder with the first piston rod extending from the first piston head through a gland in said respective end of the outer casing and carries one of said upper and lower connectors at its outer end. 5. A landing gear as claimed in claim 4 in which the first piston incorporates a restricted hydraulic aperture connecting both sides of the piston within the first piston rod for a damping action. 6. A landing gear as claimed in claim 5 in which the bore of the first cylinder is connected to the bore of the outer casing on the piston rod side of the second piston via an aperture in the rod of the second piston. 7. A landing gear as claimed in claim 5 in which a hydraulic connection is made to the bore of the first cylinder via the bore of the first piston rod. 8. A landing gear as claimed in claim 4 including a hydraulic control valve connectable to hydraulic pressure and return sources and operable to switch hydraulic pressure and return between an output connection to the second piston. 9. A landing gear as claimed in claim 8 in which the output connection to the second piston is connected to one side of the second piston, and the other side of the second piston is permanently connected to one of pressure or return sources. 10. A landing gear as claimed in claim 8 in which the hydraulic control valve is operable to connect the bore on the head side of the second piston to pressure to extend the second stage actuator, and to return to retract the second stage actuator. 11. A landing gear as claimed in claim 10 in which the bore on the piston rod side of the second piston is permanently connected to the pressure source in operation. 12. A landing gear as claimed in claim 11 in which a non-return valve is incorporated in said permanent connection to the pressure source to allow fluid flow into the said bore. 13. A landing gear as claimed in claim 12 including a pressure relief valve connected between the bore on the piston rod side of the second piston and return so as to allow fluid flow out of the bore when a set pressure is exceeded. 14. A landing gear as claimed in claim 8 in which the hydraulic control valve is operable to stop the second piston at an intermediate point in its travel so as to define a second predetermined intermediate length of auxiliary actuator different to said first predetermined intermediate length. 15. A landing gear as claimed in claim 8 in which the hydraulic control valve has a first position in which pressure and return sources are connected to opposite sides of the second piston, a second position in which pressure and return sources are connected to said opposite sides of the second piston in the opposite sense to the first position, and a third position in which the connections to opposite sides of the second piston are closed to lock pressure on opposite sides of the second piston. 16. A landing gear as claimed in claim 15 in which the hydraulic control valve forms part of a servo-control system which determines an intermediate position in which the second piston can be stopped between fully retracted and fully extended positions. 17. A landing gear as claimed in claim 16 in which a mechanical lock is provided on the casing which locks the second piston in the retracted position when activated, the mechanical lock being hydraulically activated by differential pressure in the system corresponding to retraction of the second piston. 18. A landing gear as claimed in claim 8 in which the hydraulic control valve remains in the same state for landing, taxiing and take-off.
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이 특허에 인용된 특허 (8)
Lindahl Gary M., Combined damper and truck positioner for landing gear.
Bryant, Malcom S.; Hasenoehrl, Thomas R.; Kilner, Jerome R.; Lindahl, Gary M.; Song, Taiboo, Control system and method for a semi-levered landing gear for an aircraft.
Luojus Matti N. (yrpnkatu 12 33340 Tampere FIX), Cylinder with two concentric pistons actuated by a pressure medium and extending to three times the length of the cylind.
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