LOCKING AND UNLOCKING MECHANISM

Abstract

A locking mechanism for releasably locking a lock bolt against axial movement includes a solenoid assembly arranged, in use, in proximity to an axially moveable lock bolt. The solenoid assembly includes: a solenoid, a solenoid bias spring and a solenoid plunger having a plunger tip. When the solenoid is energised, the bias spring causes the solenoid plunger to move to bring the plunger tip into locking engagement with the lock bolt to prevent axial movement thereof, and when the solenoid is not energised, the solenoid bias spring causes the solenoid plunger to move to bring the plunger tip out of locking engagement with the lock bolt thus permitting axial movement thereof.

Claims

1. A ram air turbine assembly comprising: a ram air turbine including an actuator; an axially movable lock bolt configured to actuate movement of the connected actuator; and a locking mechanism for releasably locking the lock bolt against axial movement, the locking mechanism comprising: a solenoid assembly arranged, in use, in proximity to an axially moveable member in axially movable engagement with the lock bolt, the solenoid assembly comprising: a solenoid; a solenoid bias member; and a solenoid plunger having a plunger tip; wherein when the solenoid is in a first state not being energized, the bias member causes the solenoid plunger to move to bring the plunger tip into locking engagement with the axially moveable member by securing in a recess or detent on the axially movable member to prevent axial movement of the axially movable member and the lock bolt, and when the solenoid is in a second, opposite state of being energized, the solenoid causes the solenoid plunger to move to bring the plunger tip out of locking engagement with the axially moveable member thus permitting axial movement thereof together with the lock bolt.

2. The actuator assembly of claim 1, wherein said axially moveable member comprises a piston in moveable engagement with the lock bolt.

3. The actuator assembly of claim 1, wherein the solenoid bias member comprises a spring.

4. The actuator assembly of claim 1, wherein the locking mechanism comprises two solenoid assemblies.

5. An actuator assembly comprising: an axially movable lock bolt configured to actuate movement of a connected actuator; and a locking mechanism for releasably locking the lock bolt against axial movement, the locking mechanism comprising: a solenoid assembly arranged, in use, in proximity to an axially moveable member in axially movable engagement with the lock bolt, the solenoid assembly comprising: a solenoid; a solenoid bias member; and a solenoid plunger having a plunger tip; wherein when the solenoid is in a first state of being energized, the solenoid causes the solenoid plunger to move to bring the plunger tip into locking engagement with the axially moveable member be securing in a recess or detent on the axially movable member to prevent axial movement of the axially movable member and the lock bolt, and when the solenoid is in a second, opposite state of not being energized the solenoid bias member causes the solenoid plunger to move to bring the plunger tip out of locking engagement with the axially moveable member thus permitting axial movement thereof together with the lock bolt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Preferred embodiments will now be described by way of example only and with reference to the accompanying drawings in which:

[0012] FIG. 1 shows a ram air turbine (RAT);

[0013] FIG. 2A shows a schematic view of a typical linkage release mechanism in the locked position;

[0014] FIG. 2B shows the mechanism of FIG. 2A in the unlocked position;

[0015] FIGS. 3A and 3B show a schematic view of the piston, cylinder and spring arrangement of the actuator lock bolt, which would replace the conventional mechanism shown within the dashed lines of FIGS. 2A and 2B.

[0016] FIGS. 4A and 4B show the components of FIGS. 3A and 3B in a sectional view.

DETAILED DESCRIPTION

[0017] FIG. 1 shows a RAT system 10 which is secured to an aircraft structure 12 by housing 14. The housing 14 pivotally supports a strut 16 having a turbine 18 at one end. The turbine 18 includes blades 20 which impart rotational drive to a generator 22 and a hydraulic pump 30, for example. An actuator 24 is secured to the strut at a first end 26 and to the housing at a second end 28. The actuator 24 is illustrated in its deployed position. The actuator 24 comprises a cylinder 32 which is biased by a spring 34 in order to deploy the strut 16. When the cylinder 32 is retracted, it is held in its retracted position by means of a lock bolt of a locking mechanism, details of which will be described below.

[0018] The unlocking of the actuator is initiated by permitting movement of the lock bolt 38. This is made possible by means of a release mechanism according to the present disclosure which will be described further below.

[0019] FIGS. 3A and 3B show a schematic view of the piston, cylinder and spring arrangement of the actuator lock bolt, and the release mechanism which would replace the conventional, linkage-type mechanism shown within the dashed lines of FIGS. 2A and 2B.

[0020] FIG. 3A shows the piston 39 in the locked position and, in FIG. 3B, in the unlocked position permitting movement of the piston 39 and the lock bolt for deployment of the actuator, this can be realised due to the fact that the lock bolt spring force is greater than the piston spring force.

[0021] FIGS. 4A and 4B show the components of FIGS. 3A and 3B in a sectional view.

[0022] The release mechanism comprises a solenoid 40 having a solenoid plunger 42 and a solenoid bias spring 44, the solenoid plunger having a solenoid plunger tip 46 arranged to engage with the piston 39.

[0023] In the examples shown, when the solenoid is de-energised, the solenoid bias spring biases the solenoid plunger in an extended position in which the solenoid plunger tip extends into engagement with the piston, preferably engaging it in a recess or detent in or on the piston, to prevent axial movement of the lock bolt.

[0024] When the solenoid is energised (FIG. 4B), the solenoid plunger (which is ferromagnetic) retracts due to magnetic field force creation in the solenoid, therefore the solenoid biased spring contracts and, hence, draws the solenoid plunger tip out of engagement with the piston 39, thus permitting axial movement of the piston and the lock bolt 38, against the spring 34 force.

[0025] The example shown comprises a single solenoid. It is also possible to have two or perhaps even more solenoids arranged in parallel (or coaxially) to provide redundancy and extra engagement force. If two solenoids are used, the release mechanism reacts more quickly and meets the requirements of aviation regulations for the duplication of critical systems.

[0026] An alternative embodiment could have a push-type solenoid, rather than a pull-type solenoid, in which case the solenoid would be in the locked position when the solenoid was energised and in the unlocked position when the solenoid was de-energised.

[0027] The arrangement of the present release mechanism requires significantly fewer component parts as compared to the linkage system of the prior art, which, in turn, reduces the manufacturing, assembly and testing costs and avoids the need for shims as in the prior art systems. This can result in a more reliable and smaller deployment system, as smaller forces have to be overcome by the solenoid.

[0028] This mechanism could be easily adapted to existing actuators.

[0029] When the RAT is to be retracted to the stowed position, the lock bolt 38 is moved in the opposition direction, allowing the piston to slide in the same direction as the lock bolt until the solenoid plunger tip will jump into the recess or detent, preferably located on a piston side wall, locking it in position. This movement of the piston is realised by uncompressing (expanding) the supporting spring.

[0030] The above is a description of a single embodiment by way of example only. Modifications may be made without departing from the scope of this disclosure.

[0031] While the apparatus has been described in the context of unlocking a RAT actuator, it may, as mentioned above, find use in other applications, for example of the types of actuator, valves, pumps or the like.