GB2160585A

GB2160585A - Closure member

Info

Publication number: GB2160585A
Application number: GB08412860A
Authority: GB
Inventors: Peter Arthur Gammon
Original assignee: VINTEN Ltd; W Vinten Ltd
Current assignee: VINTEN Ltd; W Vinten Ltd
Priority date: 1984-05-19
Filing date: 1984-05-19
Publication date: 1985-12-24
Also published as: JPS60259597A; IT1181678B; AU4249785A; FR2564606A1; IT8548090A0; DE3517598A1; IT8548090A1

Abstract

A closure member remotely operable to an open or closed position for protection of windows or the like in adverse conditions, especially for windows of aerial reconnaissance photographic pods, comprises a reversible electric motor (1), which moves a shutter (4) via gearing (7, 8), on electric clutch (10) and crank arms (14, 15). Elastic means (16, 17) move the shutter to an open position upon motor failure. If the motor stalls, a current sensor de-energises the clutch. Hydraulic or pneumatic power may be used. <IMAGE>

Description

SPECIFICATION Improvements in or relating to closure members This invention relates to closure members and more particularly, though not exclusively, to electrically driven closure members of the open and close type.

Though there are various fields wherein a closure member such as described in this specification may be advantageously used it is to be described in conjunction with a forward facing window of an airborne photographic reconnaissance pod.

In such pods the special optical glass windows, for normal photographic cameras, or germanium or the like windows for television type photography are very expensive and it is therefore of prime importance to avoid damage, such as scratching and nicking, caused by such as disturbed dust and gravel particles at run-up, take-off and landing.

This problem is even greater in VTOL aircraft where the jets are deflected downwards for takeoff and landing and a greater amount of foreign matter is disturbed in the vicinity of the pod which is normally underslung from a wing or the fuselage.

Closure members for pods are not new but prior art closure members have comprised of large sections of similar shape to the pod skin which have been driven to the open or closed position using chain or belt drives. One of the problems with such closure members is that it tends to increase the overall size of the pod and especially the diameter.

Invariably it is a case of the smaller the diameter of the pod the better are the aerodynamic characteristics. In some instances, to maintain this smaller diameter closure members have been made as disposable items which are latched to the pod skin, electrically or mechanically released and then aerodynamically detached from the pod to disappear earthwards; infact they are often assisted in their despatch from the pod by the use of such as an elastic catapult attached to the pod skin. Normally, actuation of these closure members occurs when the pod system is switched to STANDBY and in the case of the non-disposable closure members these are normally closed when the photographic system is switched off. Both these aforementioned types of closure members have obvious disadvantages which we intend to overcome.

It is therefore an object of this invention to provide a closure member which may be closed to protect the viewing medium and opened for photography as and when required.

According to the invention we provide a closure member operable to at least two positions comprising, a movable shutter actuated by drive means to a first of said at least two positions and reversing means for said drive means to drive said movable shutter to the second of said at least two positions.

The invention will now be described, by way of example only, in conjunction with the accompanying illustrations in which, Figure 1 shows the closure member and drive means and Figure 2 shows the closure member in the open position.

Referring to Figure 1, a pod structure, not shown, has a nose cone section part of which is generally shown as (1). Located in the nose cone section is a piece of optical glass, crystal, or germanium generally termed the viewing medium and is in general alignment and to the rear of aperture (2) in guide (3). A closure member shutter (4) preferably flexible in one plane only is slidably located in guide (3) to seal off the aperture (2) and protect the viewing medium. The closure member shutter (4) may be opened or closed as and when desired by the use of a suitable opening and closing means such as levers or a Bowden cable. Preferably, for remote, control, a reversible electric motor (5) suitably mounted on a bracket (6) drives, via a worm gear (7), a wormwheel (8) concentrically mounted on a journalled shaft (9).An electric clutch (10), when energised, couples the journalled shaft (9) to a drive gear (11) which in turn drives a driven gear (12), concentrically mounted on a second journalled shaft (13). Two crank arms (14) and (15) are each mounted at one end to the opposite ends of shaft (13) and the free ends of the crank arms (14) and (15) are secured to a top section of the closure member shutter (4). Energisation of the motor (5) to the open position and excitation of the clutch to the drive position rotates the closure member shutter ends of crank arms (14) and (15) to raise the closure member (4) within guide (3).

As the path of crank arms (14) and (15) is arcuate it is necessary for the closure member shutter to be flexible in one plane yet still retain sufficient rigidity when located in the guides (3) to withstand the extreme air pressure applied to the outward face of the closure member in flight at high speeds. This requirement is met by using a material such as Fibrelam (Registered Trade Name) and making a plurality of longitudinal slots in the viewing medium facing skin of the closure member shutter material. As the primary objective of an aerial reconnaissance pod is photography, elastic means, such as two springs (16) and (17), are fitted, one to each of the crank arms (14) and (15) to provide a "fail open" state of the closure member in the event of power failure.

Referring to Figure 2, which shows the closure member in the open position the effect of the longitudinal slots in the closure member shutter material is readily apparent. The action of the two springs (16) and (17) is also readily apparent.

A current sensing device may be advantageously fitted so that in the event of the motor stalling the electrical clutch may be disconnected to permit the elastic means to take over and open the closure member.

Though the drive means for opening and closing of the closure member has been described as electrical it will be obvious to those skilled in the art that hydraulics or pneumatics could equally well be used. It will also be obvious that though applied to a photographic pod in the specification there are numerous other applications to which such a closure member may be applied.

It will also be obvious that such refinements as change-over microswitches, actuated by the position of crank arms (14) or (15) may be incorporated to switch off power to the motor in the open and closed positions, or intermediate positions if required and prepare the circuitry for operation in the opposite direction.

Claims

1. A closure member operable to one of at least two positions comprising, a movable shutter actuated by a drive means to a first of said at least two positions and reversing means for said, drive means to drive said movable shutter to the second of said at least two positions.

2. A closure member as claimed in Claim 1 wherein said drive means comprises a motor and gearing operably connected to at least one crank arm for actuation of said closure member.

3. A closure member as claimed in Claim 1 or Claim 2 wherein an electrical clutch is energised to transfer power from said motor and gearing to said crank arm.

4. A closure member as claimed in any of Claims 1 to 3 wherein said movable shutter seals off an aperture to protect a viewing medium in general alignment therewith.

5. A closure member as claimed in Claim 4 wherein said movable shutter comprises a piece of Fibrelam (Registered Trade Name) having a plurality of longitudinal slots in the viewing medium facing skin.

6. A closure member as claimed in any preceding Claim having elastic means to ensure that said movable shutter moves to a fail open position in the event of power failure.

7. A closure member as claimed in Claim 3 having a current sensing device to de-energise said electrical clutch in the event of said motor stalling.

8. A closure member substantially as described herein with reference to Figures 1 and 2 of the accompanying drawings.