Aeronautics and astronautics – Aircraft structure – Details
Utility Patent
1999-02-04
2001-01-02
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Details
C244S129500, C244S10000R, C292S249000, C292S080000, C292SDIG001, C292SDIG001
Utility Patent
active
06168113
ABSTRACT:
BACKGROUND TO THE INVENTION
This invention relates to an assembly for retaining a catch member in a first condition and for releasing the catch member when desired for movement to a second condition. More particularly but not exclusively the invention has been designed for application as a so called uplock assembly for the latching and unlatching of a door assembly associated with the deployment and stowing of an undercarriage of an aircraft, although the invention may otherwise be applied for example to an uplock assembly for the retention and release of an undercarriage of an aircraft.
When an aircraft is landing, a door covering an undercarriage well is opened to permit the undercarriage to be deployed. When the undercarriage is deployed, the door is usually open (although on some types of aircraft the undercarriage well doors are closed when the undercarriage is deployed) and an uplock assembly thereof unlatched. When the aircraft is flying, the undercarriage is retracted into an undercarriage well for stowage and when an indication is given that the undercarriage is fully stowed, a usually hydraulic actuator is operated to close the undercarriage well door until a catch member of the door co-operates with a latch of an uplock assembly to prevent the unintentional opening of the door during flight.
To land, the uplock assembly needs to be released to permit the door to open by e.g. hydraulically aided means and/or with the aid of gravity, and the undercarriage to be lowered.
DESCRIPTION OF PRIOR ART
Known uplock assemblies are generally of a complex construction requiring complex components comprising springs, cams and levers. Not only are such known assemblies unduly heavy and complex, but they are not entirely reliable. It is known for undercarriage well doors to become jammed thus preventing the undercarriage to be lowered and making landing perilous.
Jamming can occur due to for example unfavourable operating conditions such as icy conditions.
An uplock arrangement for retaining an aircraft undercarriage is disclosed in GB 2161202A but in this arrangement, in the event of icing it is necessary to utilise a mechanically operated override to release the uplock.
SUMMARY OF THE INVENTION
According to one aspect of the present invention we provide an assembly for retaining a catch member in a first condition and for releasing the catch member for movement to a second condition, the assembly comprising a latch member pivotable about a first pivotal axis and having a formation adapted to co-operate with the catch member to retain the catch member when the latch member is in a latched position, and a rocker member pivotable about a second pivotal axis, the latch member and the rocker member interacting to retain the latch member in its latched position, the assembly further comprising actuating means to move the rocker member about the second pivotal axis to allow the latch member to pivot about the first pivotal axis to an unlatched position to release the catch member, characterised in that the latch member and the rocker member are interconnected by a resilient biasing means, the resilient biasing means including first and second relatively movable parts with a spring acting between them and a stop means which locks the first and second relatively movable parts upon a movement.
Thus utilising the invention, a lighter, less complex and therefore more reliable assembly particularly but not exclusively suited for use as an uplock assembly may be provided. When it is desired to release the catch member the actuating means positively moves the rocker member so that there is no reliance on gravity to achieve this. Furthermore, although usually the resilient biasing means will move the latch member to release the catch member in response to movement of the rocker member, in the event that the latch member is frozen or otherwise unintentionally retained in its latched position, the actuating means movement can be transmitted to the latch member, via the resilient biasing means when the stop means lock, as the resilient biasing means when locked, acts as a strut, positively to move the latch member to release the catch member.
Preferably the resilient biasing means comprises first and second relatively movable parts with a spring acting between them and there being a stop means which locks the first and second relatively movable parts upon a movement of the rocker member about the second pivotal axis beyond a threshold position.
Thus the possibilities of the catch member being unintentionally retained in the first condition are substantially reduced.
Most conveniently the spring is a compression spring which is increasingly compressed until the stop means operates.
In any event, preferably the resilient biasing means is connected to the rocker member at one side of the second pivotal axis and the actuating means is operated at an opposite side of the first pivotal axis, the rocker member comprising an abutment located on the same side of the second pivotal axis as the point of connection of the resilient biasing means which abutment co-operates with a part of the latch member to prevent the latch member rotating about the first pivotal axis beyond the latched position when the catch member is retained, and the abutment being movable when the actuating means is actuated to permit the latch member to pivot about the first pivotal axis to release the catch member.
Thus the rocker member may act as a lever.
The actuating means may be fluid operated, the assembly comprising main valve means operable to permit fluid to act to move the actuating means in a first direction to release the catch member for movement to the second condition and also preferably the main valve means is operable to permit fluid to act to move the actuating means in a second direction as the catch member is returned towards the first condition.
Although preferably the actuating means may be thus driveable e.g. by fluid operated means in a second direction opposite to the first direction, if desired the actuating means may be moved in the second direction by the rocker member as the catch member is moved to towards the first condition e.g. by some power operated means, such as a further actuator.
For example, the actuating means may be carried by a piston of a piston and cylinder arrangement, fluid acting on the piston to move the piston and hence the actuating means in the first and/or second direction, and the piston carrying an operating part which is operable to operate a check valve to open the check valve as the actuating means moves in the first direction to permit fluid to flow simultaneously to a further actuator which may be operable to move the catch member from the first to the second condition wherein the catch member is released and may be operable to move the catch member from the second to the first retained condition.
As mentioned above the assembly may be for retaining a catch member in a first condition and for releasing the catch member for movement to a second condition wherein the catch member comprises a part of a door assembly of an aircraft or part of an undercarriage of an aircraft.
According to a second aspect of the invention we provide a fluid sequencing means for operation of an assembly according to the first aspect of the invention and comprising a piston and cylinder arrangement, the piston carrying the actuating means, a main valve means to supply fluid to the cylinder to move the piston and hence the actuating means when the main valve means is in a first operating condition, and the piston carrying an operating part which is operable to operate a check valve to open the check valve as the actuating means moves in a first direction to permit fluid to flow simultaneously to a further actuator.
A piston of the further actuator may be moved in a first direction by fluid acting on one side of the piston when the main valve means is in the first operating condition, and fluid from the one side of the piston being able to pass back past the check valve when the piston is moved in a seco
Bramwell Andrew
Hann Raymond John
Rowland Peter John
Eckert Seamans Cherin & Mellot LLC
Eldred J. Woodrow
Jenkins David C.
Normalair-Garrett (Holdings) Limited
Silverman Arnold B.
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