GB2442961A

GB2442961A - Roller blind control assembly

Info

Publication number: GB2442961A
Application number: GB0620753A
Authority: GB
Inventors: Perry Day
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-10-19
Filing date: 2006-10-19
Publication date: 2008-04-23
Anticipated expiration: 2026-10-19
Also published as: GB0620753D0; GB2442961B

Abstract

A sidewinder control unit for a roller blind contains two or more wrap spring clutches 12 mounted on a wrap spring sleeve 11. The sleeve is non-rotatably received on a centre pin 10 which incorporates a sprocket support 18. The centre pin is formed with a pair of hook pins 19 and a locating pin for engagement with a mounting bracket. A slotted sprocket wheel 13 is configured to allow the sprocket to pass over the wrap spring clutches 12 whilst the opposite end has a continuous bearing ring to rotate on the wrap spring sleeve 11. The mounting assembly further includes an idle end unit which rotatably engages a bearing aperture in a second such mounting bracket.

Description

-1-2442961

ROLLER BUND MOUNTING ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

This invention relates to mountings for roller blinds, and particularly to a control unit (sidewinder) and idle end unit which are engaged with opposite ends of a roller blind carrier tube and supported by mounting brackets in use.

BACKGROUND

The market for roller blind mountings is very competitive and manufacturing costs are always a major consideration. On the other hand, the mounting assembly must look good, work smoothly and reliably, and be easy to install otherwise the rate of customer returns becomes a major concern.

One of the fundamental requirements is that the sidewinder should effectively brake the blind to prevent it from unwinding whilst at the same time permitting effortless movement of the blind when operated by means of a side chain. One of the most effective ways of achieving this is by means of a wrap spring clutch. The wrap spring is mounted on a stationary element, arranged to brake the blind when turned by the carrier tube and release its grip when the blind is operated by means of the side chain.

Many sidewinders of this kind use a single wrap spring, but the operation is improved by using two or more wrap springs. However, when the number of spring clutches is increased the moulding of the stationary element becomes increasingly critical. In existing wrap spring sidewinders the stationary component is provided by a sprocket support which is also adapted to engage the mounting bracket and is frequently combined with other functions such as locking the sidewinder assembly together and providing a chain guard housing to enclose the chain and sprocket. When the number of wrap springs increases the moulding tolerances become much more significant, and the advantages obtained by using more than one clutch are easily lost.

Other important requirements for sidewinders are that the components should be easy to assemble to minimise manufacturing costs. The sidewinder should also be easy to engage with the mounting brackets during installation yet, at the same time, the assembly should not be easy to dislodge, for example if the blind is knocked or the operating cord is tugged in an unusual manner.

The present invention seeks to provide a new and inventive roller blind mounting assembly which has a highly effective braking action, is easy to install and reliable in operation whilst at the same time having low manufacturing costs.

SUMMARY OF THE INVENTION

The present invention proposes a control unit for a roller blind which includes: -a sprocket wheel; -a sprocket support adapted to engage a mounting bracket and integrafly formed with a centre pin; -a wrap spring sleeve non-rotatably mounted on the centre pin; -a plurality of wrap spring clutches mounted on the wrap spring sleeve; -a chain guard housing located about the sprocket wheel; and -a drive bush for engagement with a roller blind carrier tube; the arrangement being such that the wrap spring clutches normally act to brake the drive bush but are released upon rotation of the sprocket wheel.

By providing a wrap spring sleeve as a separate component it is possible to ensure reliable operation of the individual clutches.

When the sprocket wheel includes a sprocket and a tubular portion which is located about the wrap springs and slotted to receive wrap spring juts the sprocket wheel preferably includes an annular wall which is formed between the sprocket and the tubular portion and which has an internal profile configured to allow passage of the wrap spring juts. The end of the tubular portion which is remote from the sprocket can be formed with a continuous bearing ring to rotate on the wrap spring sleeve.

Increased reliability can also be obtained by providing the sprocket support with a plurality of hook pins for engaging a mounting bracket. A further improvement may be achieved if the sprocket support has a locating pin for insertion into the mounting bracket.

The invention also provides an idle end unit which includes: -a centre pin having a bearing for rotatable engagement with a mounting bracket; -a compression spring located about the centre pin; and -an idle end bush for engagement with the roller blind carrier tube, the bush being slidably and non-rotatably mounted on the centre pin.

The idle end unit thus uses a minimum number of components.

The control unit and the idle end unit are preferably each engaged with a mounting bracket having a centre bearing and a plurality of hook pin apertures located about the centre bearing.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: FiQure 1 is an exploded elevation view of a roller blind mounting assembly in accordance with the invention, including a sidewinder, idle end unit and mounting brackets; Fioure 2 is an exploded general view of the sidewinder; FiQure 3 is a side view of the sidewinder; FiQure 4 is an end view of the sidewinder; Ficiure 5 is a general view of a wrap spring sleeve which is included in the sidewinder; Figure 6 is a longitudinal section through the assembled sidewinder, omitting some of the components for clarity; Figure 7 is a general view of one of the mounting brackets; and Figure 8 is an exploded general view of the idle end unit.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, a roller blind which is indicated in outline at 1 is wound on a splined carrier tube 2. One end of the tube 2 is engaged with a control unit 3 (generally referred to as a sidewinder) while the opposite end is held by an idle end support unit 4. The sidewinder 3 and idle end unit 4 are supported by mounting brackets 5, which may be screwed to a wall or window opening in various mounting positions.

Referring to Fig. 2, the sidewinder 3 comprises a centre pin 10, a wrap spring sleeve 11, at least two wrap springs 12 (three being shown in the drawings), a sprocket wheel 13, a chain guard housing 14 and a splined drive bush 15. The components are shown in the order in which they are assembled onto the centre pin 10.

The centre pin 10 has a pin body 16 which extends axially through the sidewinder and is integrally formed with a short cylindrical sprocket support 17 projecting from a disc-shaped end wall 18. As shown in Fig.s 3 and 4, the end wall 18 is formed with a pair of spaced hook pins 19 and a single locating pin 20, arranged in a triangular configuration. Returning to Fig. 2, the free end of the body 16 has a pair of spring fingers 21 and 22 which are together formed in the manner of an arrowhead to retain the drive bush 15 when the sidewinder is assembled. The pin body 16 has a series of shallow axially-extending, circumferentially-spaced fins 23 which are joined to the sprocket support 17. The centre pin is relatively easy to mould without critical tolerances.

The wrap spring sleeve 11, which is shown in more detail in Fig. 5, is substantially cylindrical with a circular external friction surface of uniform cross-section. Internally, the sleeve has a pair of diametrically-opposed channels 24 to allow free passage of the spring fingers 21 and 22 when the sidewinder is assembled. In addition, one end of the sleeve has a series of circumferentially-spaced grooves 25 which receive the fins 23 and non-rotatably key the sleeve to the centre pin 10. The wrap spring sleeve 11 is again easy to mould using a simple moulding tool, the most critical tolerance being its outer profile.

The wrap springs 12 are conventional cylindrical metal coil springs with circumferentially and axially spaced end juts 26. The wrap springs normally tightly engage the outer profile of the sleeve 11 when the sidewinder is assembled.

In the assembled sidewinder the sprocket wheel 13 is located about the sprocket support 17 and wrap spring sleeve 11. The sprocket wheel includes a sprocket 27 which is formed with an integral tubular portion 28 having an axial slot 29 which receives the juts 26 between opposed parallel edges 30. The configuration of the sprocket wheel 13 is shown more clearly in the sectional view of Fig. 6, from which the wrap springs and chain guard housing have been omitted for clarity. The sprocket 27 has a short cylindrical wall section 60 which is rotatably received on the sprocket support 17. This wall section 60 is joined to a first annular wall 61 followed by a further short cylindrical wall section 62 which together act as a bearing for the chain guard housing 14. A second annular wall 63 joins the wall section 62 to the tubular portion 28 which is radially spaced from the wrap spring sleeve 11. The opposite end of the tubular portion 28 is again stepped inwardly to form a continuous bearing ring 31 which rotates in contact with the wrap spring sleeve. It should be noted that the inner profile of the second annular wall 63 forms an extension of the axial slot 29 allowing the sprocket wheel to be assembled onto the warp spring sleeve 11 with the wrap springs already mounted on the sleeve. This considerably simplifies assembly and also permits an endless bearing ring 31 to be provided at the opposite end of the sprocket wheel, ensuring accurate alignment and smooth rotation of the sprocket wheel on the wrap spring sleeve 11.

Referring back to Fig. 2, chain guard housing 14 is shaped to enclose the sprocket 27 and includes a part-circumferential opening 32 to receive a ball chain, indicated by the broken line 33, which is engaged around the sprocket wheel in use. The housing 14 is held between the sprocket 27 and the drive bush 15, and may be free to rotate or keyed to the end wall 18 in a preferred orientation.

The drive bush 15 is profiled to be drivably engaged in the end of the carrier tube 2, with an internal rib which locates within the slot 29 between the juts 26. When the bush rotates in either direction relative to the centre pin 10 the rib engages the juts 26 to tighten the grip of the wrap spring clutches on the wrap spring sleeve 11 and thus resist rotation. On the other hand, if the sprocket wheel 13 is rotated in either direction by the ball chain 33 the opposed edges 30 engage the juts to release the grip of the wrap springs, thus allowing the sprocket wheel to drive the bush 15 via its internal rib.

The sidewinder is very easy to assemble. In addition, the close moulding tolerances of the wrap spring support ensure that the wrap spring clutches all operate with optimum performance.

The sidewinder is held by one of a pair of identical mounting brackets 5, which may be of metal or thermoplastic, one of which is shown in Fig. 7.

The bracket 5 may be provided with a snap-on cover 40, and includes a side plate 41 with a cranked apertured end 42 for attaching the bracket to a parallel wall surface. A perpendicular apertured base 43 is also provided for mounting the bracket on a perpendicular horizontal or vertical wall surface when required. The side plate 41 has a central circular bearing aperture 44 surrounded by four T-shaped holes 45. The sidewinder 3 can be engaged with the bracket by inserting the two spaced hook pins 19 and locating pin 20 into three of the holes 45. The locating pin 20 ensures that the hook pins 19 are both fully engaged with the bracket at the same time. The use of two or more hook pins 19 ensures that the sidewinder is firmly retained against accidental dislodgement from the bracket, whether by pulling the sidewinder in an axial direction or knocking the blind, and in this respect two hook pins are far better than one. Since the relative positioning of the hook pins 19 and the locating pin 20 are precisely determined by a single moutded component, namely the centre pin 10, the sidewinder can be made to have an accurate close-tolerance fit with the bracket, further reducing the danger of dislodgement.

Although the bearing aperture 44 is not used for mounting the sidewinder it enables the same bracket to be used for holding the idle end unit 4.

The idle end unit also uses a minimum number of components. Referring to Fig. 8, the idle end unit includes a splined idle end bush 49 for insertion into the idle end of the roller blind carrier tube 2 and a bearing pin 50.

The bearing pin has a pin body 51 which is integrally formed with a cylindrical abutment 52 and a stub axle 53 for rotatable reception in the bearing aperture 44 of the mounting bracket. The free end of the pin body 51 is formed with a pair of spring fingers 54 and 55 which are together shaped like an arrowhead to retain the idle end bush 49 when the unit is assembled. The bush 49 is slidably and non-rotatably received on the abutment 52 by means of an internal axial spline 56 which co-operates with an axial channel 57 in the cylindrical abutment. The bush 49 is urged against the fingers 54 and 55 by a compression spring (not shown) which is received over the pin body 51, bearing against the abutment 52.

When the roller blind assembly is inserted into the mounting brackets bearing pin 53 is first engaged with the adjacent bracket. The bush 49 can move towards the axle 53 against the action of the compression spring to allow the sidewinder to be engaged with the opposite bracket.

When the hook pins 19 are engaged with the bracket the blind cannot be accidentally dislodged.

It will be appreciated that the features disclosed herein may be present in any embodiment of the invention in any feasible combination. Whilst the above description places emphasis on those areas which, in combination, are believed to be new, protection is sought for any inventive combination of the features disclosed herein.

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Claims

1. A control unit for a roller blind which includes: -a sprocket wheel; -a sprocket support adapted to engage a mounting bracket and integrally formed with a centre pin; -a wrap spring sleeve non-rotatably mounted on the centre pin; -a plurality of wrap spring clutches mounted on the wrap spring sleeve; -a chain guard housing located about the sprocket wheel; and -a drive bush for engagement with a roller blind carrier tube; the arrangement being such that the wrap spring clutches normally act to brake the drive bush but are released upon rotation of the sprocket wheel.

2. A control unit according to Claim I in which the wrap spring sleeve is substantially cylindrical.

3. A control unit according to Claim 2 in which the wrap spring sleeve is formed with internal axial grooves which receive axial fins formed on the centre pin.

4. A control unit according to any preceding claim in which the sprocket wheel includes a sprocket and a tubular portion which is located about the wrap springs and slotted to receive wrap spring juts.

5. A control unit according to Claim 4 in which the sprocket wheel includes an annular wall which is formed between the sprocket and the tubular portion and which has an internal profile configured to allow passage of the wrap spring juts.

6. A control unit according to Claim 5 in which the end of the tubular portion which is remote from the sprocket is formed with a continuous bearing ring to rotate on the wrap spring sleeve.

7. A control unit according to any preceding claim in which the chain guard housing has a part-circumferential chain slot and is located between the sprocket wheel and the bush.

8. A control unit according to any preceding claim in which the sprocket support has a plurality of hook pins for engaging a mounting bracket.

9. A control unit according to Claim 8 in which the sprocket support has a locating pin for insertion into the mounting bracket.

10. A control unit according to any preceding claim in which the drive bush is engaged with one end of a roller blind carrier tube and the opposite end of the tube is engaged with an idle end unit.

11. A control unit according to Claim 10 in Which the idle end unit includes: -a centre pin having a bearing for rotatable engagement with a mounting bracket; -a compression spring located about the centre pin; and -an idle end bush for engagement with the roller blind carrier tube, the bush being slidably and non-rotatably mounted on the centre pin.

12. A control unit according to Claim 11 in which the idle end bush is non-rotatably received on a spring abutment formed on the centre pin.

13. A control unit according to Claim 11 or 12 in which the idle end bush is retained on the centre pin by a plurality of spring fingers which retain the idle end bush in the manner of an arrowhead.

14. A control unit according to any of Claims 10 to 13 in which the control unit and the idle end unit are each engaged with a mounting bracket having a centre bearing and a plurality of hook pin apertures located about the centre bearing.

15. A control unit for a roller blind which is substantially as described with reference to the drawings.

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