AU5406801A - A braking system for retracting screens - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE

SPECIFICATION

STANDARD

PATENT

A BRAKING SYSTEM FOR RETRACTING

SCREENS

S

S

SS S S S The invention is described in the following statement: 1 A BRAKING SYSTEM FOR RETRACTING SCREENS This invention relates to self retracting screens. In particular, it relates to a novel automatic braking system for self retracting screens.

Current self retracting screens are fitted with a roller with a recoil spring which is tensioned as the screen is drawn closed. The screen is kept closed by a locking mechanism which may be a latch, or a magnetic strip on the screen handle. When the locking mechanism is released, the recoil spring retracts the screen on to the roller at the opposite side of the screen opening.

A major disadvantage with the present state of the art self retracting screens is that, if the locking mechanism is undone and the operator releases the screen handle, the recoil spring draws the screen back onto the roller quickly and the handle impacts against the stop with some force. This has the disadvantage of(a) putting undue stress on the screen and associated parts, thus shortening their life, possibly causing injury to the operator or another person a child) who is not sufficiently clear of the screen, particularly at the roller end and (c) 15 making a loud noise which may distress those in the immediate vicinity. The greater the length of the screen, the greater is the tension in the recoil spring and consequently the screen mesh when the screen is in the closed position. Therefore, as the length of the screen increases, the speed and force of the retraction of the screen increases. This is very o dangerous, particularly in the situation where two children are near the screen and one dislodges the latch.

Another disadvantage of existing self retracting screen assemblies is that the screen cannot be positioned so that it is partly opened or partly closed. At present, there are only two r oooo positions in which the screen may be left either fully closed or fully open. It must either be fully drawn, tensioning the recoil spring in the process, and latched by the locking mechanism or fully open with the screen fully retracted in it's housing. When the operator opens the screen, and releases the handle, the recoil spring draws the screen fully onto the roller, thus fully opening the screen.

These problems are overcome by the present invention which provides a braking mechanism which is incorporated into the screen handle assembly in such a way as to automatically brake the screen when the handle is released by the operator. This mechanism causes the brake blocks to come into contact with the surface of the tracks provided as part of the screen assembly thereby providing the braking action. The present invention utilises the tension on the screen provided by the recoil spring to activate and power the brake, thereby eliminating the need for any extra mechanisms or springs. The brake is activated by the tension of the screen when the operator releases the handle. The tension in the screen also provides the braking force required.

The present invention also provides the screen assembly incorporating this braking mechanism.

The present invention also allows the screen to be positioned at any point between the fully closed and fully opened positions as, when the operator releases the screen handle, the brake automatically engages thereby holding the screen in the desired position.

Another advantage of the present invention is that it prevents the screen handle impacting against the stop with the associated noise and potential damage. This is achieved as the i operator must hold the handle for the full travel of the screen in order to fully open or close the screen If the operator releases the handle at any time during opening or closing, the rr' screen stops in that position immediately and quietly.

A description of the invention will now be given, together with an explanation of its operation, with reference to the accompanying drawings FIGS. I 2 are diagrams of the principles involved in the operation of this invention.

A lever 1 is positioned on a fulcrum at point A. A rope 4 is attached to the lever 1 at point B, passed around a pulley 2 and then taken in a direction approximately parallel to the lever 1.

'1 rJ 3 The pulley 2 is attached to the lever 1 by a supporting structure 3. When a force F is applied to the rope 4 at point D, this force is then transmitted around the pulley 2 to point B on the lever I. This then gives a reaction R at point C by the action of the lever 1 on the fulcrum A.

In both FIGS. 1 2, the ratio of force F to reaction R is equal to the ratio of the length AB to the length AC. The present invention as detailed herein utilises the geometry as shown in FIG. 1 but the geometry as shown in FIG. 2 can be used with a redesign of the handle 7 componentry.

FIG 3 is a typical view of a fully assembled screen excluding the closing jamb. The handle 7 and the roller with its recoil spring (not shown) are inserted into a frame comprising tracks 8, the roller cover assembly (9A, 9B 10) and the closing jamb (not shown) to complete a screen assembly. The completed screen assembly is fixed to the mounting surface 34 (refer FIG. 4) of the opening to be covered as explained later. The handle extrusion 5A and the mesh locking extrusion 5B as shown in FIG. 5 are joined to form unit 5 as shown in FIG. 3.

The handle 7 is an assembly of unit 5 and the end caps 6A 6B. End cap 6B is a mirror reverse of end cap 6A. The mesh 26 is clamped in unit 5 as shown in FIGS. 8 9 and feeds .oe.

onto the roller with it's recoil spring (not shown) enclosed in the roller cover comprising an assembly of end caps 9A 9B and extrusion 10 as is common practice. Any suitable fabric other suitable sheet material can be substituted for the mesh 26. The handle 7 slides between and is guided by the top and bottom tracks 8.

.eoo.i FIG. 3 shows the tracks 8 in a horizontal position with the handle 7 sliding horizontally but the fully assembled screen can also be mounted with the tracks 8 vertical and the handle 7 sliding vertically with the roller cover assembly (9A, 9B 10) in either the upper (FIG. 13) 25 or lower position (FIG. 14). FIG. 15 shows another screen assembly where two handles 7 and two rollers are mounted in one screen assembly. Either section of mesh 26 could be replaced by any suitable fabric or other suitable sheet material to provide privacy, sun protection or for any other purpose dictated by the location of the intended installation. This double ended assembly could also be mounted horizontally instead of vertically.

4 FIG. 5 shows an exploded view of the handle assembly 7 and the tracks 8. Reference should be made to this figure when reviewing the details as shown in FIGS. 4, and 6 12.

FIG. 4 shows the end view of the handle 7 and the tracks 8. The brake block 11 is inserted as shown in the brake block housing 22 which is a part of the end caps 6A 6B.

FIGS. 6 7 show the details of the end cap 6A. During assembly of the handle 7, spigots 12 13 are inserted into the cavities 14 15 of the extrusion 5A These spigots may either be fluted (spigot 12) or plain (spigot 13) as required. These spigots 12 13 allow quick and accurate assembly of the handle 7 as well as providing resistance to the twisting action of the end caps 6A 6B caused by the forces resulting from the tension in the mesh 26 and the reaction of the brake block 11 in the brake block housing 22. The rib 16 is optional, if required, to provide extra resistance to this twisting action. Slot 18 matches the cavity formed by the arc 27 in extrusion 5A and the arc 28 in extrusion 5B as shown in FIG. 8. The block 17 is positioned within the track 8 and serves a two fold purpose. Firstly, it provides S~ support to the edge of the mesh which is within the track and outside the support provided by extrusions 5A 5B. Secondly, it becomes a stop when it strikes the inner face 8D (refer FIG. 10) of the track 8 when the handle 7 is rotated. The geometry of block 17 is such that it allows the handle 7 to rotate only sufficiently to enable the removal of the brake block 11.

The brake block 11 is inserted into a recess 23 in the brake block housing 22. The recess 23 and the semi-circular back I A (refer FIG. 11) of the brake block 11 allows the brake block 11 to rotate as required to align itself with the grooves in the track 8 (refer FIG. 4) and also allows the brake block 11 to move vertically to accommodate any misalignment in .a track 8. The hole 24 allows the insertion of a screw through the end cap 6A and into the hole 1 1B of brake block 11 to retain the brake block 11 in it's position. The hole 24 is of an appropriate diameter such that the threads of the screw bite into it's surface to retain the screw in the desired position. The hole I1 B in the brake block 11 is larger than the threads of the screw to allow the brake block 11 freedom to rotate and move vertically to maintain alignment and contact with the track 8. The screw does not take any of the braking forces.

Hole 25 in the brake block housing 22 allows the insertion of a suitable device to assist the ejection of the brake block 11 from the brake block housing 22. Pivot 19 slides along the inner face 8D (refer FIG. 10) of the track 8. The pivot 19 equates tothe fulcrum A as shown in FIGS. 1 2. Holes 20 allow the insertion of suitable screws through the end caps 6A 6B into the cavities 21 in the handle extrusion 5A to lock the various components of handle 7 together.

FIG. 8 shows the handle extrusion 5A and the mesh locking extrusion 5B. As described above, cavities 14 15 receive the spigots 12 13 respectively of the end caps 6A 6B whilst the cavities 21 receive the screws which lock the various parts of handle 7 together.

Recess 31 is a cavity into which a foam (or other suitable material) strip 32 may be inserted if required. Extrusion 5B is pressed into extrusion 5A from the starting position 5BS and is latched at position 5C. Once the extrusion 5B is latched into extrusion 5A, the mesh 26 is clamped at position 33A and also at the optional position 33B. The position 33A equates to the position B as shown in FIGS. 1 2. The arc 28 on extrusion 5B is parallel to the arc 27 on extrusion 5A with sufficient clearance to allow free movement of the mesh 26 between the arcs 27 28. As the mesh 26 is free to move on the arc 27, the arc 27 equates to the pulley 2 as shown in FIGS. 1 2. The recess 35 formed by the assembly of o. extrusions 5A 5B allows the insertion of a bladed tool to disassemble the extrusions 5A 5B if required for replacement of the mesh or any other reason.

i FIG 9 shows the assembled handle 7 in position on the track 8. The tension F in the mesh 26 around the arc 27 to the clamping point 33A, acting in opposition to the pivot 19 against the ~inner face 8C of the track 8, creates a reaction force R on the brake block 11. This reaction R forces the brake block 11 into the grooves 8A (refer FIG. 10). The resulting friction between 25 the faces I IC (refer FIG. 12) and the grooves 8A creates the braking force to retain the handle 7 in the desired position.

To reposition the handle 7, the operator rotates the handle 7 in the direction M by use of the finger grip 29 in extrusion 5A or the finger grip 30 in extrusion 5B. This action releases the brake block 11 from the grooves 8A and hence disengages the brake. The handle 7 can then 6 be repositioned whilst holding the handle 7 in the rotated position. When the operator releases the handle 7, the tension F in the mesh 26 immediately rotates the handle 7 in the opposite direction to direction M thereby creating the braking effect as described above and stopping the handle 7 in that position. It should be noted that, as the handle 7 is moved from the fully open position to the fully closed position, the tension in the mesh 26 increases as the tension in the recoil spring increases. As the tension in the mesh 26 increases, so does the braking force exerted by the brake block 11 as it is powered by the tension in the mesh 26.

FIG. 10A shows the details of the track 8 as previously shown. FIG 10B shows an alternate configuration for the track for the mounting of the screen assembly within an opening instead of against the face of an opening as is shown in,FIG 1IQA. The track is fixed to the mounting surface 34 by positioning the faces 8B against the mounting surface 34 and the use of appropriate fixings through the section 8F.

FIGS. 11 12 show the plan and elevation of the brake block 11 respectively. The functioning of the various parts of the brake block 11 has been described above. The angle as shown in FIGS. 10 12 is in the range used by Vee belt technology as is well known and proven. This angle also provides the largest possible contact area between the faces 11 C of the brake block 11 and the grooves 8A of the track 8 thereby enhancing the braking effect and reducing wear to the minimum possible.

The present invention has applications other than covering widows, doors and other openings to provide exclusion of insects, sun and light from spaces within buildings. The use of a oo suitable sheet like material instead of the mesh as described herein allows this present 25 invention to be used in many other applications. These include, but are not restricted to, the Smarine industry, privacy screens, storage spaces, noise barriers, backdrops in photographic studios, scenery backdrops in the entertainment industry and wind breaks in the hospitality industry.