GB2051936A

GB2051936A - Telescopic Roller for Roller Blinds

Info

Publication number: GB2051936A
Application number: GB8021407A
Authority: GB
Original assignee: SANDLL C
Current assignee: SANDLL C
Priority date: 1979-06-29
Filing date: 1980-06-30
Publication date: 1981-01-21
Also published as: GB2051936B

Abstract

A telescopic roller (1) for a roller blind has relatively slidable outer and inner tubes (2, 3) which are formed respectively with an interengaging longitudinal key (4) and keyway (5). A locking element (6; 13) is slidable along the keyway (5) to prevent contraction of the roller when in use. <IMAGE>

Description

SPECIFICATION Telescopic Roller for Roller Blinds The invention relates to telescdpic rollers for roller blinds, comprising outer and inner relatively slidable tubes.

Roller blinds usually have to be made to order so as to fit a particular window or other cavity. It is known to provide such blinds with rollers of telescopic construction so that they can be fitted readily by a user without the need to provide a roller with a precise overall length. The main practical drawback of known telescopic rollers is the difficulty of locking together the relatively slidable components of the roller when the latter has been set at a predetermined length, since there is a tendency for the roller to contract with prolonged use, with the risk of one or both ends of the roller becoming disengaged from its supports.

An object of the present invention is to provide a telescopic roller for a roller blind having an improved method of locking the roller at a selected overall length.

According to the invention there is provided a telescopic roller for a roller blind, comprising outer and inner relatively slidable tubes, the inner tube having a longitudinally-extending keyway in which a cooperating locking element is slidable so that one end of the locking element engages the outer tube to prevent contraction of the roller.

Upon assembly of the telescopic roller, the desired overall lengths of the roller is determined and the locking element is brought into engagement with the outer tube effectively to lock the roller against contraction. In one embodiment the locking element comprises a wedge which is jammed between the tubes. In another embodiment, however, the locking element comprises a strip which is cut to a predetermined length and determines the overall length of the roller by abutting at respective ends the outer tube and an end member fitted to the inner tube. In each embodiment, the selected length of the roller remains virtually constant in use.

In order to prevent relative rotation between the inner and outer tubes the outer tube may be provided with an internal longitudinally-extending key which engages in the keyway. Preferably the key has a rectangular (including square) cross section and comprises a longitudinally-extending ridge or seam.

The locking element is retained in the keyway by providing both with complementary cross sections so that the locking element is rendered captive in the keyway. Preferably, the locking element and keyway have trapezoidal or dovetail cross-sections.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of a telescopic roller according to a first embodiment of the invention, and Figure 2 is a-similar vieuv of a second embodiment: In the drawings corresponding components are indicated by the same reference numerals.

Referring now to the drawings, there is shown a telescopic roller, generally indicated 1, which comprises an outer tube 2 of, for example, tin or zinc-plated rolled-section steel, and an inner tube 3 which is slidable in the outer tube 2 and is made, for example, from extruded aluminium. The outer tube 2 is formed with an internal longitudinally-extending seam of rectangular cross-section forming a key 4 which cooperates with a longitudinaily-extending keyway 5 of dovetail cross-section formed in and extending longitudinally throughout the entire length of the inner tube 3.

As shown in Figure 1, a longitudinallyextending locking element, comprising an extruded plastics or metal strip 6, has a crosssectional shape conforming to that of the keyway 5 and is slidable longitudinally in the keyway.

An end plug 7 fits into the end of the outer tube 2 remote from the inner tube 3 and acts as an anchorage for one end of a torsion spring 8, the other end of the spring 8 being anchored to a cap 9. Upon assembly, the cap 9 is located within the outer tube 2 and is fixed to a spindle 10 projecting coaxially through the plug 7 and rotatable therein.

A second end plug 1 1 fits over the end of the inner tube 3 remote from the outer tube 2 and supports an axially outwardly projecting spigot 12 which serves for the pivotal support of one end of the assembled roller 1.

The longitudinally-extending strip 6 is cut to a predetermined length before assembly of the roller 1 so that, when the roller is assembled with the inner tube 3 sliding telescopically within the outer tube 2 and the key 4 engaged in the keyway 5, the strip 6 abuts the key 4 at one end and the end cap 11 at the other end, thereby limiting the telescopic sliding of the inner tube 3 within the outer tube 2. When the assembled telescopic roller 1 is mounted in its supporting brackets the roller is effectively locked, being prevented from extending telescopically by its supporting brackets, and being prevented from conträction by the locking strip 6.

In the embodiment shown in Figure 2, the locking element comprises a wedge 13 which is engaged in the keyway 5 and, having a foot portion of dovetail cross-section which slides along the keyway 5, is captive therein. The wedge 13 has an external jamming surface 14 which is inclined to the base of the keyway 5, so that the wedge 1 3 tapers in height towards the end of the inner tube 3 which is located within the outer tube 2. The minimum height of the wedge 13 is less than the radial clearance between the base of the keyway 5 and the facing surface of the key 4.

The wedge 13 has an upstanding lug 15 at its larger end.

After the roller 1 has been adjusted to the desired overall length, the wedge 6 is forced into jamming engagement between the outer and inner tubes 2, 3 to lock the tubes together at this selected length, the wedge 6 being forced home by striking the lug 15 with a hammer or like tool.

The lug 15 may be struck in the opposite direction by a hammer to release the wedge 13 from its position of jamming engagement between the tubes 2, 3.

Claims

1. A telescopic roller for a roller blind, comprising outer and inner relatively slidable tubes, the inner tube having a longitudinallyextending keyway in which a cooperating locking element is slidable so that one end of the locking element engages the outer tube to prevent contraction of the roller.

2. A telescopic roller as claimed in Claim 1, in which the outer tube has an internal longitudinally-extending key which engages in the keyway of the inner tube.

3. A telescopic roller as claimed in Claim 2, in which the locking element comprises an elongate strip which at one end abuts the key of the outer tube and at the other end abuts an end member fitted to the inner tube.

4. A telescopic roller as claimed in Claim 1 or Claim 2, in which the locking element comprises a wedge which is slidable into jamming engagement with an internal surface of the outer tube to lock the tubes together.

5. A telescopic roller as claimed in any preceding claim, in which the keyway of the inner tube has a dovetail cross-section, and the locking element has a portion of complementary crosssection which is captive in the keyway.

6. A telescopic roller as claimed in Claim 2, in which the internal key is of rectangular crosssection, and comprises a longitudinally-extending ridge or seam.

7. A telescopic roller for a roller blind, substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings.