GB2408066A

GB2408066A - Latch comprising emergency release actuator

Info

Publication number: GB2408066A
Application number: GB0326502A
Authority: GB
Inventors: Robert Kyle Schmidt
Original assignee: Messier Dowty Ltd
Current assignee: Safran Landing Systems UK Ltd
Priority date: 2003-11-13
Filing date: 2003-11-13
Publication date: 2005-05-18
Also published as: GB0326502D0

Abstract

A latch assembly in which a first latch member (10) comprises a hook or claw which is pivoted to engage or disengage a second, fixed, latch member (20), and the pivoted latch member (36) is controlled by a primary latch release actuator (36). Operation of the primary release actuator (36) pivots the moveable latch member away from the fixed latch member (20) so that the two can then move apart. However, if there is a failure of the primary release actuator (36) or some other part of the latch assembly, then release may not be possible. In these circumstances, an emergency release actuator (44) serves to withdraw the fixed latch member (20) laterally of the pivot plane of the moveable latch member (10) so as to disengage the two latch members and allow two components (16,22) to which the latch members are secured, to move apart.

Description

UPLOCK AND BOLT

This invention relates to a releasable latch mechanism for holding one moveable component in a fastened position relative to another component.

Latch assemblies are used to hold moveable components in a locked position in many different applications including aerospace applications where doors may be used to close an opening for landing gear or other equipment which may need to be deployed from time to time. Typically, a latch assembly consists of a hook-shaped latch member on one component which engages a fixed latch member on the other component, and which is moveable to disengage from the fixed latch member under the control of a release actuator.

Where the operation of the latch assembly is safety critical, special care is taken to design the latch mechanism and its mode of operation so as to reduce failures to a minimum.

Nevertheless, it is impossible to avoid all modes of failure which may prevent a latch mechanism from being released.

An object of the invention is to provide an improved latch mechanism which has improved safety characteristics.

According to the invention, a latch assembly comprises a first latch member adapted for attachment to a first component, and a second latch member adapted for attachment to a second component so that the two latch members can engage when the first and second components are brought together to a fastened position, the first latch member being moveably mounted on the first component so that its movement in a first sense is controlled by a first release actuator which serves to disengage the first latch member from the second latch member to release said components from the fastened position, characterised in that one of the latch members is moveable in a second sense under the control of a second release actuator which can operate as an alternative to the first release actuator to cause the latch members to disengage and release said components from the fastened position.

Preferably, the second latch member is moveably mounted on the second component and is moveable by said second release actuator in said second sense. Preferably, said first and second senses in which the latch members are moved by the respective release actuators extend laterally of one another.

In a preferred embodiment, the first latch member comprises a hook or claw which is pivoted to engage or disengage the second, fixed, latch member, and the pivoted latch member is controlled by a primary latch release actuator. Operation of the primary release actuator pivots the moveable latch member away from the fixed latch member so that the two can then move apart. However, if there is a failure of the primary release actuator or some other part of the latch assembly, then release may not be possible. In these circumstances, an emergency release actuator serves to withdraw the fixed latch member laterally of the pivot plane of the moveable latch member so as to disengage the two latch members and allow the two components to move apart.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure I is a side elevation of a latch mechanism according to the invention as fitted to an aircraft to hold a door closed; Figure 2 is a side elevation of the latch mechanism of Figure I as seen from the left-hand side in Figure 1; Figure 3 is a side elevation of the latch mechanism of Figure I showing the latch members disengaged in a normal release mode, and Figure 4 is a section through part of the latch mechanism of Figure I showing the latch members disengaged in an emergency mode.

The illustrated latch mechanism consists of a first latch member 10 in the form of a hook pivotally mounted by a pivot pin 12 on latch body 14. The latch body 14 is secured to a door frame 16 adjacent a door opening so that the outer end of the hook 10, and specifically a notch 18 in the hook, can cooperate with a bolt 20 fxcd to a door 22, when the door is closed relative to the door frame 16 so as to hold the door closed, as shown in Figure 1.

The hook 10 is held in the bolt engaging position of Figure I by a control lever 24 which is also pivotally mounted on the latch body 14 by a pivot pin 26, and is spring loaded clockwise (spring not shown) in Figure 1. One arm 28 of the control lever 24 carries a projection 30 which cooperates with an arm 32 on the pivoted end of the hook 10 so as to prevent the hook 10 from pivoting clockwise to disengage from the bolt 20. A second arm 34 of the control lever 24 cooperates with a stop 35 and a hydraulic release actuator 36.

When the release actuator 36 is deactivated, the piston rod 38 of a ram 42 is withdrawn from the control lever 24 so that the control lever continues to hold the hook 10 in the bolt engaging position. Ilowcver, when the release actuator 36 is activated via hydraulic lines 40, the ram 42 extends the piston rod 38 to engage the second arm 34 and pivot the control lever 24 anti-clockwise against its spring loading to disengage the projection 30 from the arm 32 of the hook 10. The hook 10 is then free to rotate clockwise to disengage from the bolt 20 and release the door 22.

A spring (not shown) serves to rotate the hook 10 clockwise to the released position, shown in Figure 3. An extension 37 of a rear portion of the notch 18 lies in the path of the bolt 20 as the door 22 is closed so that it is engaged by the bolt 20 and pivots the hook to the bolt engaging position. The arm 32 will then engage the projection 30 to displace the control lever 24, before this returns under its spring loading to engage beneath the arm 32 to hold it in the bolt engaging position.

In the event of failure of the hydraulic release actuator 36, the latch can alternatively be released manually by a mechanism which pivots the stop 35 so that it cams against the control lever 24 and causes the latter to rotate in the anti-clockwise, release direction.

According to the invention, another alternative latch release mechanism is provided. This takes the form of an electrical actuator 44 (although it will be appreciated that hydraulic, pneumatic or manual actuators may also be used) which serves to withdraw the bolt 20 axially away from the hook 10 and out of engagement with the notch 18. As shown in Figure 4, the bolt 20 is formed with an armature 46, which, when energised, serves to withdraw the bolt. Spring loading (not shown) serves to return the bolt to its normal extended position in the path of movement of the hook 20 for normal latching operation.

It will be appreciated that the actuator 44 can be provided to withdraw the bolt 20 in any latch assembly, and not just the particular latch assembly illustrated in the drawings.

Claims

Claims 1. A latch assembly comprising a first latch member adapted for

attachment to a first component, and a second latch member adapted for attachment to a second component so that the two latch members can engage when the first and second components are brought together to a fastened position, the first latch member being moveably mounted on the first component so that its movement in a first sense is controlled by a first release actuator which serves to disengage the first latch member from the second latch member to release said components from the fastened position, characterised in that one of the latch members is moveable in a second sense under the control of a second release actuator which can operate as an alternative to the first release actuator to cause the latch members to disengage and release said components from the fastened position.
2. A latch assembly as claimed in claim 1 in which the second latch member is moveably mounted on the second component and is moveable by said second release actuator in said second sense.
3. A latch assembly as claimed in claim 1 or 2 in which said first and second senses in which the latch members are moved by the respective release actuators extend laterally of one another.
4. A latch assembly as claimed in any of the preceding claims in which the first latch member comprises a hook or claw which is pivoted to engage or disengage the second latch member, and in which the first latch member is controlled by a primary latch release actuator which pivots the first latch member away from the second latch member so that the two can then move apart.
5. A latch assembly as claimed in claim 4 in which the second release actuator comprises an emergency release actuator which serves to withdraw the latch member laterally of the pivot plane of the first latch member so as to disengage the two latch members and allow the two components to move apart.
6. A door assembly including a latch assembly as claimed in any one of the preceding claims.
7. A latch assembly substantially as herein described with reference to the accompanying drawings