GB2415009A

GB2415009A - Rotatable closure members

Info

Publication number: GB2415009A
Application number: GB0412745A
Authority: GB
Inventors: Julian Wilcox
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-06-08
Filing date: 2004-06-08
Publication date: 2005-12-14
Also published as: GB0412745D0

Abstract

An apparatus 1 for closing an aperture, for example a window, has first and second rotatably mounted closure members 3, 5, rotatable from a closed position in which they are adjacent and obscure the aperture and an open position in which they overlap and reveal the aperture, a mechanism being provided wherein rotation of one closure member in one direction causes rotation of the other closure member in the opposite direction. Also disclosed is an aperture closure in which first and second closure members are rotatable about a first axis from a closed to open position and at least one of the first and second closure members is also rotatable about a second axis, perpendicular to the first axis.

Description

24 1 5009 - 1 -

APPARATUS FOR CLOSING AN APERTURE

The present application relates to apparatus for closing an aperture. More particularly, the present application relates to closure apparatus for forming a window, door, gate, valve or the like.

It is known to provide circular windows in buildings to provide an attractive design feature. These windows are typically opened by pivoting them about an axis in the plane of the window. However, this arrangement may be undesirable as a portion (typically half) of the window tends to project into the interior of the building when the window is open.

This can present an obstacle which is undesirable and the size of the window may have to be limited. A window of this type is disclosed in FR 2722830.

An alternative arrangement having two semicircular sashes, rotatable about an axis perpendicular to the plane of the window, is disclosed in CA 2048840. The semicircular sashes are rotated to a position where they overlap to form an opening in the window. This arrangement has the advantage that the window does not extend into the building when it is opened. However, the semicircular sashes may tend to rotate under their own weight, unless they are positioned with their centres of gravity directly above or below the axis about which they rotate. This tendency would clearly be undesirable.

A further circular window is known from JP 57-084943. This window comprises two semi-circular portions which are rotatable about a common axis in opposite directions.

However, the semi-circular portions each rotate out of the plane defined by the window in its closed position and may, therefore, present an obstacle when the window is opened.

The practical applications in which this arrangement can be employed may be limited.

The present application relates to apparatus for closing an aperture which, at least in preferred embodiments, ameliorates or overcomes the problems outlined above.

Viewed from a first aspect, the present application relates to apparatus for closing an aperture, the apparatus comprising first and second rotatably mounted closure members, and at least one mechanism for rotating the first and second closure members relative to each other; the first and second closure members being rotatable from a closed position to a first open position, the first and second members overlapping or overlaying each other in said first open position; wherein rotation of the first member in a first direction causes the at least one mechanism to rotate the second member in a second direction, the first direction being opposite to the second direction.

Viewed from a further aspect, the present application relates to apparatus for closing an aperture, the apparatus comprising first and second rotatably mounted closure members, and at least one mechanism for rotating the first and second closure members relative to each other; the first and second closure members being rotatable in parallel planes from a closed position to a first open position; wherein rotation of the first closure member in a first direction causes said at least one mechanism to rotate the second closure member in a second direction, the first direction being opposite to the second direction. - 3 -

The provision of at least one mechanism to rotate the first and second closure members relative to each other advantageously means that the user need only rotate one of the closure members and the other closure member will automatically be rotated. Moreover, the rotation of the first and second closure members in opposite directions means that the first and second closure members at least partially counterbalance each other.

The first and second closure members preferably create equal but opposite moments to counter-balance the apparatus. The first or second closure member may be heavier than the other of said first and second closure members and still counter balance the apparatus, provided the centres of gravity of the closure members are arranged appropriately relative to the axis about which they rotate. The centre of gravity of the heavier closure member may, for example, be closer to an axis of rotation.

Preferably, however, the first and second closure members are of equal mass and have corresponding centres of gravity (such that the distance from the centre of gravity of each closure member to the axis about which they rotate is the same). This arrangement is especially desirable as it means that the closure members will counterbalance each other and thereby minimise the force which must be applied to rotate them. Moreover, in this arrangement, the tendency of the first and second closure members to rotate under their own weight will be reduced or avoided.

The first and second closure members preferably define a circle when they are in the closed position. Preferably, - 4 the first and second closure members are both semi-circular.

It will be appreciated that more than two closure members may be provided, each defining, for example, a sector of a circle. There may, for example, be four closure members each defining a quadrant of a circle.

The first and second closure members preferably rotate about a first axis to said first open position. The first and second closure members preferably overlay each other completely in said first open position, but it will be appreciated that they may overlap each other, for example, when they have been rotated through less than 90 . In other words, the first and second closure members preferably at least partially cover each other in said first open position. The first axis is preferably perpendicular to the plane of the closure members when they are in the closed position. In arrangements where the closure members define a circle when in said closed position, the first axis preferably passes through the centre of said circle.

The first and/or second closure member(s) may also be rotatable about a second axis to a second open position.

The second axis is preferably arranged substantially perpendicularly to the first axis. The rotation of the first and/or second members is preferably facilitated when the first and second closure members completely overlay each other and/or they are in the closed position. Rotating the closure members to the second open position advantageously allows the aperture to be opened still further.

Most preferably, the first and second closure members may both be rotated about the second axis in the same direction.

Thus, the closure members may open to a first side of the closure apparatus leaving the other side unobstructed. This arrangement is particularly desirable when the apparatus forms a window as the first and second closure members may both open outwardly without impinging on the space inside the building.

The apparatus preferably comprises a frame member in which the first and second closure members are rotatably mounted.

Although the frame member may be provided with an axle about which the first and second closure members rotate, the frame member is preferably provided with a first channel for receiving an outer portion of the first closure member and a second channel for receiving an outer portion of the second closure member. The first and second channels preferably define circular paths inside of which the first and second closure members may be rotated.

The closure members may each be provided with diametrically opposed pins which are received in the respective first and second channels in the frame member. This arrangement advantageously may allow the first and second closure members to rotate about the second axis without interfering with the first and second channels (as only the pins are received in the channels).

Preferably, the apparatus comprises a travelling semi- circular sub-frame also having first and second channels defined therein. In this arrangement, the outer portion of the first and second closure members may be received in the first and second channels in the sub-frame and the first and second closure members rotated to said first open position.

The outer portions of the first and second closure members are preferably entirely received in the first and second - 6 - channels formed in the sub-frame when the closure members are in said first open position. The sub-frame is preferably pivotably mounted to allow rotation about the second axis. Thus, the first and second closure members may be rotated, together with the sub-frame, about the second axis to a second open position. The sub-frame is preferably provided in a plane between the first and second closure members. When the closure members are rotated about the first axis to a position in which they overlay each other completely, the sub-frame is preferably sandwiched between them. This arrangement allows the sub-frame at least partially to be hidden from view by the closure members.

Moreover, the sub-frame may be provided with a deeper section to improve buckling and stability characteristics.

The sub-frame should preferably be sufficiently rigid to carry the weight of the first and second closure members but preferably be of low profile so as to reduce or minimise impact on the aesthetics of the apparatus, at least in preferred embodiments. Advantageously the mechanism for effecting counter-rotation of the first and second closure members may provide positive engagement between the first and second closure members as they are rotated about said second axis.

The mechanism for effecting counter-rotation of the first and second closure members is preferably mounted on the semi-circular sub-frame in arrangements where the closure members are also to rotate about said second axis. This arrangement advantageously allows the closure members to rotate without interfering with said mechanism. If required, a compression strut may be provided to support said mechanism. The compression strut preferably extends to - 7 a pivot point of the sub- frame, for example at a 45 angle to the horizontal, to provide a compressive load path.

Thus, the compression strut would define a chord in the lower quadrant of the first and second closure members if they are semi-circular and in the first open position.

The aperture to be closed is preferably circular, but it will be appreciated that one or more inserts may be provided on one or both sides of the frame member to define an aperture having a different shape. Equally, the frame member in which the first and second closure members are provided may have an outer shape which is non-circular, but retains the first and second circular channels inside of which the closure members may rotate. For example, the frame member may have a square plan form to allow it more readily to be installed.

Viewed from a still further aspect, the present invention relates to an apparatus for closing an aperture, the apparatus comprising first and second closure members; the first and second closure members being rotatable about the first axis from a closed position to a first open position, the first and second members overlapping or overlaying each other in said first open position; at least one of said first and second members being rotatable about a second axis to a second open position, the second axis being perpendicular to the first axis.

The apparatus preferably comprises at least one mechanism for rotating the first and second closure members relative to each other. - 8 -

In arrangements where the first and second closure members also pivot about a second axis to a second open position, the first and second closure members may be biased towards a plane perpendicular to the first and second axes. A spring or other bias means may be provided for this purpose. If the closure apparatus forms a valve in a conduit, the flow of fluid through the conduit may bias the first and second closure members towards the second open position; and the bias means may return the closure members to (or at least bias them towards) the first open position when the fluid flow in the conduit is reduced.

It will, of course, be appreciated that an actuator or the like may be provided to rotate the first and second closure members about said first axis. Similarly, a first actuator may be provided to rotate the first closure member about the first axis; and a second actuator to rotate the second closure member about the first axis. The first and second actuators preferably being arranged to rotate the first and second closure members in opposite directions. The first and second actuators may operate simultaneously and for the same period of time to ensure that the closure members undergo the same angular rotation. Alternatively, control means may be provided to determine when the first and/or second closure members have undergone predetermined angular rotation. For example, the control means may determine when the first and/or second closure members have rotated through 45 or 90 . The control means may also monitor rotation of the first closure member and control rotation of the second closure member to ensure that they undergo the same angular rotation.

Moreover, an actuator (or actuators) may be provided to rotate the first and/or second closure member(s) about said second axis.

The apparatus may comprise one, two, three or more counter- rotation mechanisms for rotating the closure members relative to each other. The mechanism(s) preferably comprises a rotatable element, such as a gear wheel or a roller, which is rotated in response to rotation of the first and second closure members. The rotatable element is preferably located between the first and second closure members and is co-operable with adjacent surfaces thereof.

Advantageously, the rotatable element may engage both closure members and enforce equal and opposite rotation thereof. To facilitate automatic operation of the closure apparatus, a motor or other actuator may be provided to drive the rotatable element.

In arrangements where the rotary element is a gear wheel, the first and second closure elements are preferably provided with a circumferential toothed region co-operable with the teeth on said gear wheel. If a roller or the like is to be used, the outer surface of the roller may be provided with a rubber coating or the like so as to make better contact with the closure members.

In arrangements in which the closure members are also to rotate about a second axis, first and second diametrically opposed counter-rotating mechanisms may be provided. The mechanisms may each comprise a rotatable element, such as a gear or roller, rotatably mounted on the second axis. This configuration advantageously enables the first and second closure members to rotate about the counter-rotation - 10 mechanisms. The channels formed in the support frame and the sub-frame may also each have a curved region at one end thereof in which pins provided on the closure members are positively (and preferably also automatically) lockable and which create the required hinge condition to allow rotation of the closure members about said second axis.

The apparatus preferably also comprises at least one locking mechanism, mounted on the frame, sub-frame or at least one of the closure members, to lock the first and second closure members and prevent further rotation relative to each other.

The first and second closure members may be at a pre- determined angle relative to each other or a user may actuate the locking mechanism to lock them at any desired angle. Preferably the locking mechanism is actuated automatically when the first and second closure members completely overlay each other. In arrangements whereby the at least one locking mechanism is mounted on the first and/or second closure members, at least one pin is provided on the support frame or the sub- frame and the at least one pin is locked in the locking mechanism to prevent further rotation of the first and second closure members. A converse arrangement is also envisaged whereby the at least one locking mechanism is mounted in the frame or sub-frame and at least one pin is provided on the first and/or second closure members for cooperation therewith. The locking mechanism may be released, for example to allow the first and second closure members to be closed. . A safety mechanism may be provided to prevent incomplete engagement of the closure members or any other risk to the interface with the closure members.

The first and second counter-rotation mechanisms for rotating the closure members are preferably operatively connected, for example by a shaft, to each other to effect rotation of the rotatable elements. Depending on the location and arrangement of the mechanisms, counter-rotation or commonrotation of the rotatable elements may be required. For example, if the subassemblies are mounted on the same side of the closure panels commonrotation would be required, but if they are between the closure panels counter-rotation would be required. Counter-rotation of the rotatable elements may be effected by providing a third gear rotatably mounted on the supporting frame to cause the rotatable elements to rotate in equal but opposite directions. A supporting semi-circular sub-frame may be provided to bear at least a portion of the weight of the first and second closure members when they are rotated about said second axis.

The closure apparatus described herein may form a window, door, gate or valve.

In arrangements where the apparatus is to be used for a window, the first and second closure members preferably each comprise a sash and a pane of glass or other transparent planar member. Alternatively, the closure members may simply be a transparent planar member without a sash being provided.

The initial rotating operation of the first and second closure members to said first open position allows for significant pressure differentials on either side of the apparatus to be carried without necessitating a significant increase in the force required to actuate it. - 12

If component egress is not an issue on one side of the aperture, then after the initial opening has been created by rotation of the first and second closure members about the first axis, fluid flow will occur reducing any pressure differential across the remaining semi-circle which can then be opened to any degree required by pivoting about said second axis with much less force than might otherwise be required, for example by a simple hinge gate arrangement.

When the first and/or second closure members are pivoted about the second axis, the closure members can additionally be utilized to provide directional control of any fluid flow as it flows into and out of the aperture. This functionality is particularly desirable if the apparatus is provided in the face of a surface or in a nozzle, rather than housed in a tube or like conduit.

A further modification to the apparatus described herein is to facilitate simultaneous rotation of the first and second closure members about both the first and second axes. This functionality is advantageous insofar as it allows control of two angular degrees of freedom permitting the control of fluid flow in any direction. To allow simultaneous rotation of the closure members about the X and Y axis, the apparatus may further comprise a second sub-frame in which the first sub-frame is mounted. The second sub-frame may be mounted on the support frame and be rotatable about the first axis.

The second sub-frame is preferably circular. Alternatively, the locking mechanism or locating pins provided on the sub- frame or the closure members may be rotatable, for example in a circumferential groove or track provided in the supporting frame. It may also be desirable to provide a 13 second locking mechanism to lock the second sub-frame relative to the support frame. A further alternative would be to allow the support frame to rotate about the first axis.

When the apparatus is in the form of a window, at least in preferred embodiments the invention provides a non- intrusive, non-hazardous circular window placed in preferred embodiments. Moreover, the design lends itself to opening and closing to be achieved at a distance, either by a manual mechanism or remote control. This functionality is particularly desirable when the apparatus is to form a circular window as these are often located for aesthetic architectural reasons under the apex of a roof where ventilation is efficient if an aperture can be controlled in this typically high out-of-reach location.

Viewed from a further aspect, the present invention relates to a window assembly comprising first and second rotatably mounted sashes, and at least one mechanism for rotating the first and second sashes relative to each other; the first and second sashes being rotatable from a closed position to an open position, the first and second sashes overlapping or overlaying each other in said open position; wherein rotation of the first sash in a first direction causes said at least one mechanism to rotate the second sash in a second direction, the first direction being opposite to the second direction.

Viewed from a yet further aspect, the present invention relates to a window assembly comprising first and second rotatably mounted sashes, and at least one mechanism for rotating the first and second sashes relative to each other; - 14 the first and second sashes being rotatable in parallel planes from a closed position to an open position; wherein rotation of the first sash in a first direction causes said at least one mechanism to rotate the second sash in a second direction, the first direction being opposite to the second direction.

Viewed from a still further aspect, the present invention relates to a window assembly comprising first and second sashes; the first and second sashes being rotatable about a first axis from a closed position to a first open position, the first and second sashes overlapping or overlaying each other in said first open position; at least one of said first and second sashes being rotatable about a second axis perpendicular to the first axis when in said closed position and/or said first open position.

The term "overlap", and derivatives thereof, as used herein means to extend over so as to cover partly. The term "overlay", and derivates thereof, as used herein means to cover completely.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which: Figure 1 shows a window assembly in accordance with the present invention in a closed position; Figure 2 shows a side view of the window assembly of Figure 1 and details of a counter-rotating mechanism; Figure 3 shows the window assembly in a partially opened position with the first and second closure members having been rotated through 45 about a first axis; Figure 4 shows the window assembly in an intermediate open position with the first and second closure members overlayed; and Figure 5 shows the window assembly in a second open position with the first and second closure members rotated through 60 about a second axis by way of example.

A circular window assembly 1 for installation in a building in accordance with the present invention is shown schematically in Figure 1. The window assembly 1 comprises a first closure member 3 and a second closure member 5. The first and second closure members 3, 5 are each made up of a semicircular sash and a matching pane of glass (not shown).

The closure members 3,5 are rotatably mounted in a circular frame member 7 and a semi-circular sub-frame member 8. The closure members 3, 5 are rotatable about a first axis X (which extends perpendicular to the drawing sheet in Figure 1), and the sub-frame member 8 is rotatable about a second axis Y perpendicular to the first axis. The first axis X passes through the centre of the circle defined by the frame member 7 and the second axis Y extends along a diameter of the same circle.

The first closure member 3 is rotatably mounted in a first circumferential channel (not shown) provided in the frame member 7 and the sub-frame member 8. The second closure member 5 is rotatably mounted in a second channel (not shown) also provided in the frame member 7 and the sub-frame member 8. The first and second channels define parallel tracks spaced from each other to allow the first and second closure members 3, 5 to rotate without interfering with each other. The outer circumferential portions of the first and second closure members 3, 5 are received in the respective 16 first and second channels to facilitate rotation about the first axis X. As shown in Figure 2, a counter-rotation mechanism 9 is provided between the first and second closure members 3, 5.

The counter-rotation mechanism 9 is mounted on the sub-frame member 8 and co-operates with both the first and second closure members 3, 5 when they are in a closed position.

The counter-rotation mechanism 9 comprises a gear wheel 11 which is rotatable about an axis 13 extending along a radius of the window assembly 1. The first closure member 3 is provided with a first circumferential toothed region 15 and the second closure member 5 is provided with a second circumferential toothed region 17. The first and second toothed regions 15, 17 cooperate with the teeth provided on the gear wheel 11 such that rotation of the first or second closure members 3, 5 causes the gear wheel 11 to rotate and effect rotation of the other of said first or second closure members 3, 5 in the opposite direction.

As shown in Figure 3, rotation of the first closure member 3 in a counterclockwise direction causes the second closure member 5 to rotate in a clockwise direction, as shown by arrows 19 and 21 respectively. The first and second closure members 3, 5 rotate through 90 degrees until they overlay each other in an intermediate open position, as shown in Figure 4. In this intermediate open position, the first and second closure members 3, 5 are supported by the sub-frame member 8 (such that they do not extend into the portions of the first and second tracks defined in the frame member 7). - 17

From the intermediate open position, the first and second closure members 3, 5 may pivot about the second axis Y together with the sub-frame member 8. The second axis Y is perpendicular to the axis 13 of the gear wheel 11.

As shown in Figure 5, the first and second closure members 3, 5 pivot about the second axis Y in the same direction, as shown by arrow 23 in Figure 5. Thus, the first and second closure members 3, 5 may rotate through 90 degrees about the second axis Y to a second open position. Figure 5 shows the first and second closure members 3, 5 in a position having been rotated through approximately 60 degrees by way of

example only.

When the first and second closure members 3, 5 have been displaced to the intermediate open position they are locked in position in the sub-frame member 7 by a locking mechanism (not shown). The first and second closure members 3, 5 may then be rotated about the second axis Y together with the sub-frame member 8.

When the first and second closure members 3, 5 are in the intermediate open position, they lie exactly on top of each other thereby taking the shape and cross-sectional area of only one semi-circle. This geometrical transformation is relatively simple to engineer and actuate, and allows an opening of a closed circular aperture into: 1. a semi-circular aperture with no components Aggressing into the immediate volume around the aperture, as described by the above 90 degree rotation about the first axis X to the intermediate open position; and - 18 2. then subsequently opened further to a second open position with components only on one side of the aperture by rotating the resulting semi-circle around the second axis Y formed by its base parameter.

Furthermore, for structures of more significant mass, such as windows, another feature of the geometrical transformation can be employed; the rotation of the transformation of two semi-circular components from a circular configuration to an overlaid semi-circular configuration, asdescribed above, moves the combined centre of gravity of the two semicircles along a straight line (if the two semi-circular components are of equal mass and identical centre of gravity).

A special case can be arranged where the two semi-circles are initially arranged to form a circle on a vertical plane but with their aligned bases in a horizontal plane, as shown in Figure 1. Then, when they are rotated in opposite directions by 90 degrees it is found that their combined centres of gravity do not change position in a vertical sense. Therefore, if the two semi-circles are connected by a counter-rotation mechanism 9, or a similar mechanism, then they act as each other's counter-balance and are stable in any position, provided the supporting structure is designed to carry any loads due to the moment created by a lateral offset of the combined centre of gravity. This rotational counter-balancing feature is also valid for a pair of semi- circles rotating in an inclined plane, if their bases are horizontal when they are in the closed position.

The embodiment described herein employs a configuration which allows the centre of gravity of the first and second closure members 3, 5 to translate along a horizontal path.

Although a gear mechanism has been described for effecting counterrotation of the first and second closure members 3, 5, it will be appreciated that other possible mechanisms could be employed to achieve this effect.

In the preferred embodiment, the adopted mechanism for enforcing counterrotation of the first and second closure members 3, 5 is located at the interface of the supporting frame 7 and the perimeter of the closure panels 3, 5 in the form of rotational guides or tracks with bearings for the closure panels 3, 5 to rotate but still be otherwise constrained in the other five degrees of freedom, and a gear 11 provided to control the relative movement of the panels in their one open degree of freedom they possess relative to the supporting frame 7.

In an alternative arrangement (not shown), the first and second closure members 3, 5 and the support frame 7 may all be provided inside a second frame member (not shown) inside of which the first frame member 7 may rotate about the first axis X. This arrangement advantageously allows the first and second closure members 3, 5 simultaneously to be rotated about both the first and second axes X, Y. Although the embodiment described herein shows only one counter-rotation mechanism 9, it will be appreciated that more than one such mechanism may be provided, for example spaced circumferentially around the frame member 7. The provision of more than one counter-rotation mechanism 9 would allow the first and second closure members 3, 5 to be rotated about the first axis X in the opposite direction to that shown in Figure 3 (i.e. with the first closure member 3 being rotated in a clockwise direction).

It will be appreciated that additional sealing elements, such as flexible seals, may be provided to improved the seal between the first and second closure members when they are in the closed position. - 21

Claims

CLAIMS: 1. Apparatus for closing an aperture, the apparatus comprising

first and second rotatably mounted closure members, and at least one mechanism for rotating the first and second closure members relative to each other; the first and second closure members being rotatable from a closed position to an open position, the first and second closure members overlapping or overlaying each other in said open position; wherein rotation of the first closure member in a first direction causes said at least one mechanism to rotate the second closure member in a second direction, the first direction being opposite to the second direction.
2. Apparatus for closing an aperture, the apparatus comprising first and second rotatably mounted closure members, and at least one mechanism for rotating the first and second closure members relative to each other; the first and second closure members being rotatable in parallel planes from a closed position to a first open position; wherein rotation of the first closure member in a first direction causes said at least one mechanism to rotate the second closure member in a second direction, the first direction being opposite to the second direction.
3. Apparatus as claimed in claim 1 or 2, wherein said first and second closure members at least partially counterbalance each other.
4. Apparatus as claimed in claim 1, 2 or 3, wherein said first and second closure members overlay each other when in said first open position. - 22
5. Apparatus as claimed in any one of claims 1 to 4 further comprising a frame member in which the first and second closure members are rotatably mounted, the first and second closure members being rotatable in said frame from the closed position to the first open position about a first axis.
6. Apparatus as claimed in claim 5, wherein said first and/or second closure member(s) is/are also rotatable about a second axis, said second axis being perpendicular to the first axis.
7. Apparatus as claimed in claim 6 further comprising a sub-frame member rotatable about said second axis, the first and/or second closure member(s) being rotatable about said second axis with the sub-frame member.
8. Apparatus as claimed in claim 7, wherein the first and second closure members are completely supported by the sub- frame member when they are in said first open position.
9. Apparatus as claimed in claim 7 or 8 further comprising a locking mechanism for locking the first and second closure members in said subframe.
10. Apparatus as claimed in any one of claims 6 to 9, wherein said first and second closure members are rotatable about said second axis only when they are in said first open position.
11. Apparatus as claimed in any preceding claim, wherein each mechanism comprises a rotatably mounted gear wheel. - 23
12. Apparatus as claimed in claim 11, wherein said gear wheel is cooperable with toothed tracks formed in the first and second closure members.
13. Apparatus as claimed in claim 11 or 12, further comprising a motor for rotating said gear wheel.
14. Apparatus as claimed in any one of claim 1 to 10, wherein each mechanism comprises a rotatable roller.
15. Apparatus as claimed in claim 14, further comprising a motor for rotating said roller.
16. Apparatus for closing an aperture, the apparatus comprising first and second closure members; the first and second closure members being rotatable about a first axis from a closed position to a first open position, the first and second closure members overlapping or overlaying each other in said first open position; at least one of said first and second closure members being rotatable about a second axis perpendicular to the first axis when in said closed position and/or said first open position.
17. Apparatus as claimed in claim 16 further comprising at least one mechanism for rotating the first and second closure members relative to each other.
18. Apparatus as claimed in claim 17, wherein rotation of the first closure member in a first direction causes said mechanism to rotate the second closure member in a second direction, the first direction being opposite to the second direction.
19. Apparatus as claimed in claim 16, 17 or 18, wherein said first and second closure members at least partially counterbalance each other.
20. Apparatus as claimed in any preceding claim, wherein the first and second closure members are semicircular in plan form.
21. Apparatus as claimed in any preceding claim, wherein the aperture to be closed is circular.
22. Apparatus as claimed in any preceding claim, wherein said first and/or second closure member(s) comprise a transparent member and the apparatus forms a window.
23. Apparatus as claimed in any preceding claim, wherein the first closure member is a first sash and the second closure member is a second sash.
24. A window assembly comprising first and second rotatably mounted sashes, and at least one mechanism for rotating the first and second sashes relative to each other; the first and second sashes being rotatable from a closed position to an open position, the first and second sashes overlapping or overlaying each other in said open position; wherein rotation of the first sash in a first direction causes said at least one mechanism to rotate the second sash in a second direction, the first direction being opposite to the second direction.
25. A window assembly comprising first and second rotatably mounted sashes, and at least one mechanism for rotating the - 25 first and second sashes relative to each other; the first and second sashes being rotatable in parallel planes from a closed position to an open position; wherein rotation of the first sash in a first direction causes said at least one mechanism to rotate the second sash in a second direction, the first direction being opposite to the second direction.
26. A window assembly comprising first and second sashes; the first and second sashes being rotatable about a first axis from a closed position to a first open position, the first and second sashes overlapping or overlaying each other in said first open position; at least one of said first and second sashes being rotatable about a second axis perpendicular to the first axis when in said closed position and/or said first open position.
27. Apparatus for closing an aperture substantially as herein described with reference to the accompanying drawings.
28. A window assembly substantially as herein described with reference to the accompanying drawings.