GB2486555A

GB2486555A - Roller blind drive assembly with braking action

Info

Publication number: GB2486555A
Application number: GB201121418A
Authority: GB
Inventors: Perry Day
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-12-15
Filing date: 2011-12-13
Publication date: 2012-06-20
Anticipated expiration: 2031-12-13
Also published as: GB201121418D0; GB201021302D0; EP2466053A2; EP2466053A3; GB2486555B

Abstract

A drive assembly for a roller blind includes a housing 1 having a projecting shaft 10. A first gear 11 is contained within the housing co-axial with the shaft, and a second worm gear 12 engaged with the first gear 11 and rotatable by a wand or rotating rod. A clutch member in the form of a spring 13 encircles the shaft with a pair of spaced tangs 14 15. A drive member 16 has a cylindrical outer portion 18 located about the shaft 10 and the clutch 13, and an inner pin 17 which engages the first gear 11. A spigot 4 connects with the roller and is received over the outer portion of the drive member 16. The drive member 16 has a slot 22 and the spigot has an internal rib 25 which engage the tangs of the clutch spring 13. Rotation of the drive member 16 via the wand causes the spring 13 to release its grip on the shaft 10 allowing rotation of the spigot 4. Rotation of the spigot 4 other than by the drive member 16 causes the spring 13 to tighten its grip on the shaft and thereby resist rotation of the spigot.

Description

CORDLESS DRIVE ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

This invention relates to a drive assembly for operating a blind.

BACKGROUND

A common form of drive assembly for winding and unwinding a roller blind has a pulley rotated by a looped drive cord. A spring would on a fixed shaft acts as a clutch which allows the roller to be rotated by the cord, but if the roller rotates other than by means of the drive cord the spring tightens its grip on the shaft to prevent the roller from rotating.

In recent years there have been a number of tragic accidents caused by young children becoming entangled with the drive cord of a roller blind.

The present invention seeks to provide a new and inventive form of cordless drive assembly which uses inexpensive components, is quick and easy to assemble, yet provides an effective and reliable braking action.

SUMMARY OF THE INVENTION

The present invention proposes a drive assembly for operating a blind, which includes: -a housing provided with a projection; -a first gear located within the housing; -a second gear drivably engaged with the first gear within the housing and rotatable by a wand which is external to the housing; -a spigot adapted for operating the blind and which is received over said projection and arranged to be driven by the first gear; and -a clutch member which engages the projection and the spigot to resist rotation of the spigot other then by the wand.

The drive assembly preferably includes a drive member engaged with the first gear and the spigot and having a portion which is located about the external projection and the clutch member.

The clutch member is preferably coiled around the external projection.

The clutch member preferably has projecting ends.

The drive member and the spigot are preferably adapted for engagement with the projecting ends of the clutch member such that rotation of the drive member by means of the wand and gear wheels causes the clutch member to release its grip on the external projection allowing such rotational movement to be transmitted to the spigot, and rotation of the spigot other than by the drive member causes the clutch member to tighten its grip on the external projection and thereby resist rotation of the spigot.

The invention more particularly provides a drive assembly for a roller having sheet material wound thereon, which includes: -a housing having a shaft which projects therefrom; -a first gear contained within the housing and rotatable about a first axis which is substantially co-axial with the shaft; -a second gear drivably engaged with the first gear and rotatable about a second axis, the second gear being rotatable by a wand which projects from the housing; -a clutch member which encircles the shaft, said clutch member having a pair of circumferentially spaced ends; -a drive member having an outer portion which is located about the shaft and the clutch member, and an inner portion which projects through the shaft and is drivably engaged with the first gear; -a spigot adapted for connection with the roller and which is received over said outer portion of the drive member and driveably engageable therewith; the drive member and the spigot being adapted for engagement with the said ends of the clutch member such that rotation of the drive member by means of the wand and gear wheels causes the clutch member to release its grip on the shaft allowing such rotational movement to be transmitted to the spigot, and rotation of the spigot other than by the drive member causes the clutch member to tighten its grip on the shaft and thereby resist rotation of the spigot.

The first gear is preferably of greater diameter than the second gear. The second gear is preferably a worm. The first gear preferably rotates more than once for each rotation of the second gear.

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: Figure 1 is a general view of a cordless drive assembly in accordance with the invention for operating a roller blind; and Figure 2 is an exploded view of the drive assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, the roller drive assembly comprises a moulded plastics housing 1 which includes a rear part 2 and a front part 3 which are snap-engaged or otherwise secured together, e.g. by screws. The rear part 2 is adapted in known manner for engagement with a mounting bracket (not shown), while the front part 3 is adapted to carry a rotatable spigot 4 which may have external splines 5 for driving connection within the end of a roller (not shown) on which a blind is wound. A rotatable member 6 projects from the bottom of the housing 1 and is drivably connected to a wand 7 via a pivotal connection, e.g. a hook 8 inserted through a transverse aperture in the member 6. The connection may be made permanent by closing the hook 8 after assembly or by passing a flexible sleeve 9 over the hook. The spigot 4 and the associated roller can be rotated to wind the blind on and off the roller by rotating the wand 7, as described below.

Referring to Fig. 2, the front part 3 of the housing 1 is formed with an integral tubular shaft 10. The housing 1 contains a first gear 11 which can rotate about a first axis which is substantially co-axial with the shaft 10. A second gear in the form of a worm 12 is formed on the rotatable member 6, meshed with the first gear 11. The rotation axis of the rotatable member 6 and worm 12 is orthogonal to that of the first gear 11. The first gear is also of smaller diameter than that of the worm 12, providing a worm-to-gear drive ratio of approximately 1:2.

The tubular shaft 10 carries a clutch member in the form of a helical coil spring 13 which encircles the shaft for a number of turns, the inside diameter of the spring being slightly less than the outside diameter of the shaft 10. The ends of the spring 13 are out-turned to form a pair of circumferentially spaced projecting drive tangs 14 and 15.

A drive member 16 has an inner pin 17 and an outer cylindrical portion 18 joined by an end wall 19. The cylindrical portion 18 is located about the shaft 10 and spring 13 while the pin 17 passes axially through the interior of the shaft 10 terminating in a non-circular end 20 which is drivably engaged with the first gear 11. The outer cylindrical portion 18 contains an axial slot 22 in which the drive tangs 14 and 15 are received. The front end of the pin 17 is formed with a pair of spring fingers 23 which each carry a locking projection 24.

The spigot 4 is generally cup-shaped and is a close sliding fit over the cylindrical outer portion 18 of the drive member 16.

The spigot 4 includes an internal axial rib 25 which is located between the tangs 14 and 15 within the slot 22. The assembly is held together by the locking projections 24 which spring outwardly when the fingers 23 pass through an apertured end wall 26.

Rotation of the drive member 16 in either direction by means of the wand 7 and gear wheels 11, 12 causes the tangs 14 and 15 to contact the sides of the slot 22. This unwinds the spring causing it to release its grip on the shaft 10. The rotation of the drive member 16 is transmitted to the spigot 4 via the rib 25, allowing the blind to be wound onto or unwound from the roller.

Rotation of the spigot 4 other than by the drive member, e.g. under the weight of the blind, causes the rib 25 to engage one or other of the tangs 14 and 15 which winds up the spring causing it to tighten its grip on the shaft 10 and thereby resist further rotation of the spigot.

All components of the drive assembly except the spring may be moulded from plastics.

By using an appropriately wound spring it would be possible to tighten the spring onto the shaft 10 by moving the tangs together and release the grip by moving the tangs apart. In this case the tangs would be located between internal stops on the spigot 4 and the drive member 16 would need a drive projection between the tangs. It would also be possible to mount the spring clutch inside the tubular shaft 10. The important thing is that the spring is released when the wand and gears rotate the spigot 4 but otherwise acts as a brake between the spigot and the fixed components to prevent rotation of the spigot.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

* * * * * * * *

Claims

CLAIMS1. A drive assembly for operating a blind, which includes: -a housing provided with a projection; -a first gear located within the housing; -a second gear drivably engaged with the first gear within the housing and rotatable by a wand which is external to the housing; -a spigot adapted for operating the blind and which is received over said projection and arranged to be driven by the first gear; and -a clutch member which engages the projection and the spigot to resist rotation of the spigot other then by the wand.
2. A drive assembly according to Claim 1 which includes a drive member engaged with the first gear and the spigot and having a portion which is located about the external projection and the clutch member.
3. A drive assembly according to Claim 2 in which the clutch member is coiled around the external projection.
4. A drive assembly according to Claim 3 in which the clutch member has projecting ends.
5. A drive assembly according to Claim 4 in which the drive member and the spigot are adapted for engagement with the -10 -projecting ends of the clutch member such that rotation of the drive member by means of the wand and gear wheels causes the clutch member to release its grip on the external projection allowing such rotational movement to be transmitted to the spigot, and rotation of the spigot other than by the drive member causes the clutch member to tighten its grip on the external projection and thereby resist rotation of the spigot.
6. A drive assembly for a roller having sheet material wound thereon, which includes: -a housing having a shaft which projects therefrom; -a first gear contained within the housing and rotatable about a first axis which is substantially co-axial with the shaft; -a second gear drivably engaged with the first gear and rotatable about a second axis, the second gear being rotatable by a wand which projects from the housing; -a clutch member which encircles the shaft, said clutch member having a pair of circumferentially spaced ends; -a drive member having an outer portion which is located about the shaft and the clutch member, and an inner portion which projects through the shaft and is drivably engaged with the first gear; -a spigot adapted for connection with the roller and which is received over said outer portion of the drive member and driveably engageable therewith; the drive member and the spigot being adapted for engagement with the said ends of the clutch member such that rotation of the drive member by means of the wand and gear wheels -11 -causes the clutch member to release its grip on the shaft allowing such rotational movement to be transmitted to the spigot, and rotation of the spigot other than by the drive member causes the clutch member to tighten its grip on the shaft and thereby resist rotation of the spigot.
7. A drive assembly according to any preceding claim in which the first gear is of greater diameter than the second gear.
8. A drive assembly according to any preceding claim in
9. A drive assembly according to any preceding claim in which the first gear rotates more than once for each rotation of the second gear.
10. A drive assembly according to any preceding claim in which the wand is coupled to the second gear by a pivotal connection.
11. A drive assembly for a roller having sheet material wound thereon substantially as described with reference to the drawings.* * * * * * * *