Aircraft landing gear with orientable lower part

Patent metadata

Field	Value
Publication number	US-10287003-B2
Application number	US-201515109955-A
Country	US
Kind code	B2
Filing date	Jan 6, 2015
Priority date	Jan 14, 2014
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

Aircraft landing gear ( 100 ) provided with a bottom portion ( 110 ) that is steerable by means of a steering actuator ( 1 ) comprising a toothed wheel ( 70 ) that is secured to the steerable bottom portion ( 110 ) and that co-operates with a rack ( 20 ) that is movable in translation along an axial travel axis (X) and that has ends ( 21 a, 21 b ) connected to pistons ( 30 a, 30 b ) mounted to slide in respective cylinders ( 10 a, 10 b ). Each connection between one of the pistons ( 30 a, 30 b ) and the associated end of the rack ( 20 ) presents play (J) at least axially, and possibly also angular play (E), and at least one sealing gasket, referred to as an internal gasket ( 25 ), between the rack ( 20 ) and a piston ( 30 a, 30 b ), the gasket being arranged to oppose movements of the rack ( 20 ) relative to the pistons ( 30 a, 30 b ).

First claim

The invention claimed is:

1. An aircraft landing gear ( 100 ) provided with a bottom portion ( 110 ) that is steerable by means of a steering actuator ( 1 ) comprising a toothed wheel ( 70 ) that is secured to the steerable bottom portion ( 110 ) and that co-operates with a rack ( 20 ) that is movable in translation along an axial travel axis (X) and that has ends ( 21 a , 21 b ) connected to pistons ( 30 a , 30 b ) mounted to slide in respective cylinders ( 10 a , 10 b ),
the landing gear being characterized in that each connection between one of the pistons ( 30 a , 30 b ) and the associated end of the rack ( 20 ) presents play (J) at least axially and at least one sealing gasket, referred to as an internal gasket ( 25 ), between the rack ( 20 ) and a piston ( 30 a , 30 b ), the gasket being arranged to oppose movements of the rack ( 20 ) relative to the pistons ( 30 a , 30 b ),
wherein each end ( 21 a , 21 b ) of the rack ( 20 ) is cylindrical in shape and is received in a cylindrical bore ( 31 a ) of the piston ( 30 a , 30 b ) that is associated therewith so as to allow the rack ( 20 ) to slide axially relative to each of the pistons ( 30 a , 30 b ) and
wherein each of the connections between a piston ( 30 a , 30 b ) and the rack ( 20 ) presents a ball joint ( 80 a , 80 b ) with a spherical surface ( 83 ) that co-operates with a complementary spherical surface ( 33 ) formed on the piston ( 30 ) to allow the piston ( 30 a , 30 b ) to swivel relative to the rack ( 20 ), said spherical surface ( 83 ) of the ball joint being concave towards the piston against which it comes to bear so as to encourage centering of the piston ( 30 a ) against the ball joint ( 80 a ).

2. The aircraft landing gear ( 100 ) according to claim 1 , wherein each piston ( 30 a , 30 b ) mounted to slide in a cylinder ( 10 a , 10 b ) carries at least one external sealing gasket ( 35 ) for providing sealing between the piston ( 30 a , 30 b ) and the corresponding cylinder ( 10 a , 10 b ) in which it slides.

3. The aircraft landing gear ( 100 ) according to claim 2 , wherein, for each given piston, the internal sealing gasket ( 25 ) and the external sealing gasket ( 35 ) associated with the given piston are arranged so that during axial movements of the rack ( 20 ) relative to the given piston along said axial travel direction (X), the internal sealing gasket ( 25 ) generates an internal axial friction force opposing the axial movement of the rack ( 20 ) relative to the given piston, and the external sealing gasket ( 35 ) generates an external axial friction force opposing the movement of the given piston relative to the cylinder ( 10 a , 10 b ) in which it slides, the external axial friction force associated with the given piston ( 30 a , 30 b ) being strictly greater than the internal axial friction force associated with the same given piston ( 30 a , 30 b ).

4. The aircraft landing gear ( 100 ) according to claim 3 , wherein each given piston ( 30 a , 30 b ) co-operates with the cylinder ( 10 a , 10 b ) in which it slides to define a hydraulic chamber ( 15 a , 15 b ), and the internal and external sealing gaskets ( 25 , 35 ) associated with the given piston ( 30 a , 30 b ) are arranged so that, within the limit of a predetermined pressure range, and regardless of the pressure applied in said hydraulic chamber ( 15 a , 15 b ) defined by the given piston ( 30 a , 30 b ), the external axial friction force is always greater than the internal axial friction force.

Assignees

• Messier Bugatti Dowty

Inventors

• La Commara Domenico

Classifications

• B64C25/34

  wheeled type, e.g. multi-wheeled bogies · CPC title

• F15B15/1452

  Piston sealings · CPC title

• F15B15/1447

  Pistons; Piston to piston rod assemblies · CPC title

• F15B15/065

  the motor being of the rack-and-pinion type · CPC title

• B64C25/50 Primary

  Steerable undercarriages; Shimmy-damping · CPC title