GB2180872A

GB2180872A - Roller drive assembly

Info

Publication number: GB2180872A
Application number: GB08622241A
Authority: GB
Inventors: Perry Day
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-09-27
Filing date: 1986-09-16
Publication date: 1987-04-08
Also published as: GB8523875D0; GB2180872B; GB8622241D0

Abstract

A drive assembly for a roller having a blind or other sheet material wound upon it comprises a housing 7 containing a wheel member 8. The wheel member includes a pulley 9, a spigot 13 for connection to the roller, and a single axle 14. The housing has an internal boss 18 providing a bearing in which the axle 14 is an interference fit to prevent unwinding of the sheet material. A drive cord 20 passes through an aperture 21 and is looped around the pulley 9. Cam faces 22, 23 urge the cord between the cheeks of the pulley and if the pulley is rotated other than by the cord 20 the cord is carried between one of the cam faces 22, 23 and the pulley and jams, thereby preventing further rotation of the wheel member. The wheel member can then be released by pulling either cord tail. <IMAGE>

Description

SPECIFICATION Roller drive assembly This invention pertains to a drive assembly for a rollerhaving a blind, map, chart orsimilarsheet material wound upon it. The assembly is used to wind and unwind the material from the roller and permits the material to be retained in any arbitrary position between the fully wound and fully unwound positions.

European Patent Specification No. 86 000 discloses such an assemblywhich is purported to meet thereon quirement of being made and assembled in a very simple mannerfrom a minimum of component parts. Nevertheless, that drive assembly requires at leastfourmoulded parts, namely a pulley,atwo-part housing and a locking shoe.

In many applications such drive assemblies must meet a further requirement, namely that the width of the assembly should be as small as possible. Thus, when the roller is installed in a defined opening such as a window frame for example, the gap at the side of the material beneath the drive assembly is kept to a minimum.

The aim of this invention isto provide a form of drive assembly which is capable of meeting the above requirements, i.e. reducing the number of essential components still further and reducing the overall width taken up by the assembly.

According to the present invention, the solution lies in the provision of a drive assembly for a roller having sheet material wound thereon, comprising a wheel member adapted for driving connectiontothe roller, the wheel member being provided with a single axle or bearing, the axle or bearing cooperating with a bearing or axle respectively provided by a further memberwhich is fixed in use, and a flexible drive element being looped around the wheel memberforwinding and unwinding the sheet material on and off the roller, and the drive assembly including braking meansfor preventing the sheet material from turning the roller under its own weight.

The use of a single bearing atthe drive assembly end of the roller allows the number of essential com- ponents other than the drive element to be reduced to two, namely the wheel memberandthefixed member. Furthermore, the elimination of one of the bearings for the wheel member allows the overall width of the assembly to be reduced.

The fixed member is preferably assembled on the opposite side ofthe wheel member to the roller.

Thewheel memberand drive element may com- prise a toothed wheel and a chain for example.

The braking means may comprise a frictional coupling between a surface which rotates with the wheel member and a fixed surface, which is preferably provided by the fixed member.

In a preferred arrangement the wheel member comprises a pulley having its internal faces arranged to griptheflexible drive element, cam surfaces being provided to urge the drive element between the internal faces of the pulley, the arrangement being such that if the pulley is turned other than by the drive element the drive element jams between one of the cam surfaces and the pulley, thus preventing the material from unwinding from the roller.

The flexible drive element is preferably a cord.

The invention will now be exemplified with refer encetotheaccompanying drawings, in which: Figure lisa general perspective view of a roller blind fitted with an end drive assembly in accordance with the invention, Figure2 is a part-sectional view of the drive assembly with the drive cord omitted, Figure3 is a section on line Ill-Ill of Figure 2, and Figures4and5aresimilarviewsto Figure3but showing the drive cord in the normal and locked pos itions respectively.

In Figure ia a blind is wound upon a tubular metal or cardboard roller 2. One end of the roller is prov ided with a conventional end bearing 3 which is sup ported by a metal mounting bracket 4 fitted, for ex- ample, to a window frame. The other end ofthe roller is provided with a drive assembly 5 supported by a further mounting bracket 6.

The drive assembly comprises a generally cupshaped one-piece moulded plastics housing 7 (Fig ures 2 and 3) containing a wheel member 8, which is also a one-piece plastics moulding.

The wheel member 8 includes a pulley section 9 comprising a drum portion 10 disposed between a pair of side cheeks 11. The inner faces of the side cheeks have circumferentially spaced ribs 12 running between their inner and outer peripheries. From one side of the pulley9 projects a criciform spigot-like section 13 for insertion into an end of roller 2 so asto form a driving connection between the wheel member and the roller. An axle 14 having a reduced end portion 15 extends from the opposite side of the pulley.

The housing 7 includes a short, generally cylindrical wall portion 16 that encloses the pulley with only a small radial clearance. The housing is closed at one end by a wall 17 containing a central, inwardly directed boss 18 that receives the axle 14 as an interfer ence fit to provide a bearing for the wheel member. A pairoflocating pinsi9(Figurei)projectoutwardly from end wall 17 and pass through bracket 6 so that the housing 7 is thus non rotatablyfixed in position.

reduced axle portion 15 also projects through the bracket.

At the bottom of housing 7 a drive cord 20 (Figure 4) passesthrough an aperture21 in wall 16, loops around the pulley 9 and re-emerges from the housing via aperture 21. A pair of curved cam faces 22, 23 formed at opposite circumferential ends of aperture 21 urgethecord between the cheeks 11 of the pulley, between which the cord is a tight fit. The ribs 12 improve the grip on the cord, helping to preventitfrom slipping.

In use, the blind is raised and lowered by pulling the appropriate tail of cord 20 to rotate the pulley within housing 7 and so rotate the roller 2.

In the case of a lightweight blind 1 the frictional coupling between axle 14and bearing 18will usually be sufficient to prevent the roller from turning under the weight of the blind. However, in the case of a heavier blind, or if the bearing should wear through prolonged use,the roller may startto turn in direc tion Aforexample (Figure 5). lfthis happensthecord will be carried between the opposite cam face 23 and the pulley and will jam as shown in Figure 5, preventing further rotation in that direction. The roller can be released again simply by pulling either cord tail.

The axle 14 and bearing 18 could be transposed so thatthe housing 7 carries the axle and the wheel member 8 contains the bearing aperture.

The wheel member and the housing could each be made in more than one partatgreatermanufacturing cost.

Claims

1. A drive assembly for a roller having sheet material wound thereon, comprising a wheel member adapted for driving connection to the roller, the wheel member being provided with a single axie or bearing, the axle or bearing co-operating with a bearing or axle respectively provided by a further member which is fixed in use, and a flexible drive element being looped around the wheel memberfor winding and unwinding the sheet material on and off the roller, and the drive assembly including braking means for preventing the sheet material from turning the roller under its own weight.

2. An assembly as specified in Claim 1, in which the fixed member is assembled on the opposite side of the wheel memberto the roller.

3. An assembly as specified in Claim 1 or 2, in which the braking means comprises a frictional coupling between a surface which rotates with the wheel member and a fixed surface.

4. An assembly as specified in Claim 3, in which the said fixed surface is provided bythefixed member.

5. An assembly as specified in Claim 4, in which the said surfaces are provided by the axle and bearing.

6. An assembly as specified in any preceding claim, in which the wheel member comprises a pulley having its internal faces arranged to grip the flexible drive element, and cam surfaces are provided to urge the drive element between the internal faces ofthe pulley, the arrangement being such that if the pulley is turned other than by the drive element the drive element jams between one of the cam faces and the pulley, thus preventing the material from unwinding from the roller.

7. An assembly as specified in Claim 6, in which the cam surfaces are provided by the fixed member.

8. An assembly as specified in any preceding claim, in which the fixed member encloses the wheel member.

9. An assembly as specified in Claim 8, in which the fixed member is generally cup-shaped and encloses the wheel member withy only a small radial clearance.

10. An assembly as specified in any preceding claim, including a mounting bracket for supporting the fixed member.

11. An assembly as specified in any preceding claim, in which the flexible drive element is a cord.

12. A drive assembly for a roller having sheet material wound thereon, having any novel combination offeaturesdisclosed herein.

13. A drive assembly for a roller having sheet material wound thereon, substantially as described with reference to the drawings.