Aeronautics and astronautics – Landing gear – Retractable
Reexamination Certificate
1998-03-19
2001-10-30
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Landing gear
Retractable
Reexamination Certificate
active
06308916
ABSTRACT:
BACKGROUND
The invention is in the field of hydraulic actuation mechanisms for positioning aircraft landing gear components, and more particularly relates to a dual mode positioner for an aircraft landing gear axle beam.
Hydraulic systems are commonly used in the aircraft landing gear art for positioning landing gear components and for providing dynamically damped movement of such components. In certain prior art landing gear, hydraulic control systems and actuation means are used to control the position of various aircraft landing gear components to alternatively configure the landing gear for extension out of the aircraft prior to landing and taxi or for retraction into the aircraft during flight. Such systems and actuating devices have been used to position an aircraft landing gear axle beam. In certain other prior art landing gear, positioners are used to maintain the position of the axle beam relative to the landing gear shock strut during taxi. The positioner includes a dynamic damping device that damps incremental rotational motion of the axle beam relative the shock strut during aircraft taxi as may be induced by runway roughness.
Weight and complexity are desirably minimized in aircraft while maintaining the level of functionality needed to meet particular design constraints. Certain aircraft landing gears need both an actuating device and a positioner. Therefore, it is an object of this invention to provide both the actuating and positioning functions with minimum weight and complexity.
SUMMARY
According to an aspect of the invention, a dual mode positioner is provided comprising an actuating device that positions an aircraft axle beam relative to an aircraft strut alternatively for taxi or retraction into the aircraft, and also provides a predetermined amount of damping of the axle beam during taxi.
According to a further aspect of the invention, a dual mode positioner is provided filled with hydraulic fluid for positioning an aircraft landing gear axle beam, the axle beam being pivotally attached to a shock strut configured for attachment to an aircraft in a manner that permits retraction, the aircraft having a hydraulic system with a high pressure supply and a low pressure return, comprising:
a first hydraulic line;
a second hydraulic line;
a hydraulic actuating device connected to the first and second hydraulic lines and having a first end configured for pivotal attachment to the shock strut and a second end configured for pivotal attachment to the axle beam, the hydraulic actuating device being responsive to hydraulic pressure in the first and second hydraulic lines such that it has a contracted mode that places the axle beam in a first angular position relative to the shock strut suitable for taxi and an extended mode that places the axle beam in a second angular position relative to the shock strut suitable for retraction, the hydraulic actuating device being incrementally extendable and contractible with a predetermined amount of damping while the hydraulic actuating device is in the contracted mode to provide damped pivotal movement of the axle beam relative to the shock strut during aircraft taxi; and,
a control valve connected to the first and second hydraulic lines and having a taxi configuration wherein the second hydraulic line is in fluid communication with the high pressure supply and the first hydraulic line is in fluid communication with the low pressure return thereby placing the hydraulic actuating device in the contracted mode, and a retract configuration wherein the first hydraulic line is in fluid communication with the high pressure supply and the second hydraulic line is in fluid communication with the low pressure return thereby placing the hydraulic actuating device in the extended mode.
According to a further aspect of the invention, a method of positioning the angular orientation of an aircraft axle beam connected to a shock strut is provided, comprising the steps of changing an angular orientation of an aircraft axle beam connected to an aircraft shock strut alternatively for taxi or retraction into the aircraft with a hydraulic actuating device, and providing a predetermined. amount of damping of incremental rotational movement of the axle beam relative to the shock strut during taxi using the hydraulic actuating device.
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patent: 0 295 174 A1 (1988-12-01), None
patent: 0 705 758 A1 (1996-10-01), None
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patent: WO 96/17770 (1996-06-01), None
patent: WO 99/47416 (1999-03-01), None
Disclosure A. Prior Art Positioner Without Extension During Retract, with attachment showing Fig. 1 and Fig. 2.
Disclosure B. Prior Art Positioner With Extension During Retract, with attachment showing Fig. 1 and Fig. 2.
Brinks Hofer Gilson & Lione
Eldred J. Woodrow
The B. F. Goodrich Company
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