WO1988002055A1

WO1988002055A1 - An apparatus for lifting and lowering slats in a blind

Info

Publication number: WO1988002055A1
Application number: PCT/SE1987/000417
Authority: WO
Inventors: John Archer
Original assignee: Ambient Energy Design O.P.M. Ab
Priority date: 1986-09-19
Filing date: 1987-09-15
Publication date: 1988-03-24
Also published as: AU8021887A; SE8603948D0; SE8603948L

Abstract

In a rail (15) arranged above a blind is positioned a screw-formed element (3) extending within the rail along its extension. Feed means (6, 7) co-operate with the screw-formed element for winding cords (4, 5) on and off said element upon relative movement between said element and said feed means. Motor drive means (2) is arranged in the rail (15) for rotation of said screw-formed element (3) for said winding. Said drive means (2) preferably consists of a motor and gearbox unit including a slip coupling (19) and also including means (11, 12) for turning the blind slats.

Description

AN APPARATUS FOR LIFTING AND LOWERING SLATS IN A BLIND

The present invention relates to blinds for fitting inside double or triple glas windows or, if the windows are her¬ metically sealed, inside the windows. Blinds of this kind are made of slat bands normally 25 or 35 mm wide.

A conventional blind has two functions, namely as sun shelter and for hindering insight through the window.

In recent years also a so called heat insulating blind has been constructed, which has slats reflecting heat back into the building. This heat insulating blind is described in Swe¬ dish patent No. 7514471-7 (publication No. 400 601) . It is also necessary for a heat insulating blind to be tightly closed if it is to be effective as heat insulator. In some buildings opening and closing the blinds may be difficult be¬ cause the windows are positioned in inconvenient places. Also the lifting and lowering of the blinds can be difficult. It is clearly a great advantage if the blinds can be operated remotely using a small electric motor. An apparatus for twist- ing blinds for opening and closing them using a small electric motor and gearbox is described in Swedish patent No. 8203173-3 (publication No. 450 143) . However, lifting and lowering the blinds has not been possible because of the extra complication involved, the difficulty of where to accomodate the lifting cords as the blind is lifted, and the comparatively large forces involved in lifting the blind.

A small electric motor and gearbox can produce a torque of 20.000 gram mm; however, this is totally inadequate when the lifting cords must be wound onto a pulley that can be up to 20 mm in diameter and a blind can weigh up to 5 kg. Another problem which occurs is the coiling of the lifting cords as the blind is raised. Such cords are normally 1.2 to 2 mm in diameter and a blind can be up to 2 meters high with cords of the same length. Collecting these cords, as they are wound up, in a tidy and orderly manner can be a problem. Also the whole lifting mechanism should preferably be housed within a top rail of the blind. A top rail is only approximately 27 mm wide and 19 mm high. Moreover, the lifting mechanism shall operate in a reliable manner and with minimum risk to be destroyed.

The present invention has been developed in order to overcome the above mentioned problems and provide an apparatus that operates reliably and requires a small space.

In this respect the present invention relates to a apparatus for lifting and lowering a blind as stated in the preamble part of claim 1 and the characteristics of the invention appear from the characterizing part of claim 1.

The invention will now be described more in detail with refer- ence to the accompanying drawings, which somewhat schematic¬ ally illustrate some embodiments of the invention.

Fig. 1 is a perspective view showing a block incorporation with a screw. Fig. 2 is a central side view of a rail arranged above the blind for illustrating one embodiment of an apparatus according to the invention. Fig. 3 is a view corresponding to Fig. 2 and illustrating an¬ other embodiment. Fig. 4 is a side view illustrating a blind with a rail arranged above the blind. «

Fig. 5 is a perspective view illustrating a motor and gearbox unit.

_A block (6 in Fig. 2) is threaded on a screwed shaft 3, as shown in Fig. 1. The block has cut-outs on each side to allow place for the lifting cord for the blind. There is a roller 1 on one side to guide the cord onto the screwed shaft 3.

The assembly of the screwed shaft 3 and a motor and gearbox unit 2 arranged in the rail 15 positioned above the blind is shown in Fig. 2. In this embodiment the screwed shaft 3 is arranged instead of the normal center shaft of a blind. The motor and gearbox unit 2 , which is fastened in the rail 15, is attached to the screwed shaft 3 so that when the output shaft of the gearbox rotates the screwed shaft 3 does too. Cords 4 and 5 for lifting the blind are fixed to the shaft an then fed around the guide roller 1 of the block. As appears from Fig. 2 one of the cords, the cord 5, also is drawn aroun another roller 10 fixed to the rail 15 before the cord is dra through the blind and attached at 14 to a bottom rail 16 (see Fig. 4) of the blind. This arrangement of the cords is made b cause both blocks 6, 7 shown in Fig. 2 move in the same di¬ rection and the length of the cord drawn up depends not only on the rotation of the shaft but also to a small extent on th movement of the blocks relative to roller boxes 8 and 9. How¬ ever, when the fixed roller 10 is used exactly equal cord lengths are drawn up irrespective of the fact that one block 6 is moving away from the roller box 8 and the other block 7 is moving towards the roller box 9.

As the screwed shaft 3 rotates the lifting cords 4 , 5 are dra up and wound in a correct orderly fashion around the screwed shaft.

In Fig. 3 an embodiment using only one block for both lifting cords is shown. In this embodiment the cord 5 is fed around t fixed roller 10 to ensure that both cords 4 and 5 are drawn u at the same speed.

Thus, a device as shown in the embodiments operates in such a manner that screwed element in the form of a screwed shaft or screw is rotated by a small motor and gearbox unit arranged in a top rail above the blind. When the screw is rotated it moves at least one feed element in the form of a block, which slides along the inside of the top rail and draws with it the lifting cord (or cords) , which is allowed to wind around the screw. The screw can be a replacement for the center shaft at present used for a blind. Alternatively it may be a length of a hollow screwed section which is fitted over an existing shaft.

Moreover, the gearbox unit 2 incorporates preferably a slip coupling so that when the blind is fully drawn up the slit coupling comes into operation. This means that the motor can be allowed to run for some time even when the blind is fully lifted without there being any danger of the motor burning out as would otherwise occur if it was held stationary while current being supplied. ^

The motor and gearbox can also serve to rotate (twist) the slats to open and close the blind. This is achieved by having twist rollers 11 and 12 in the normal position in the roller boxes 8 and 9, however, the ends of step cords are not fasten¬ ed to the twist rollers but hang on them, i.e. two ends of each step cord are fastened together and a step cord then hangs as a loop over the twist rollers. There is sufficient friction between the step cord and the twist roller to ensure that the slats open and close. When the blind is being lifted or lowered the step cords just slide on the twist rollers. This urther -function of the motor and gearbox unit has its importance in that the slats will be positioned horizontally, which is necessary for a correct lifting of the blind.

In Fig. 5 the motor and gear box unit 2 is shown schematically in larger scale, including the motor 17, the gearbox 18 and the slip coupling 19.

A device according to the invention can be constructed in other ways than described above and shown on the drawings without de- parting from the inventive idea defined in the following claims

Claims

CLAIMS : -

1. An apparatus for lifting and lowering a blind consist ing of a number of thin slats, wherein cords (4, 5) for lift ing and lowering the blind are drawn from fastening position (14) at the bottom of the blind to a rail (15) or the like p sitioned above the blind for winding up or winding off the cords in the rail upon said lifting or lowering of the blind including a screw-formed element (3) arranged in the extensi of the rail (15) and at least one feed means (6, 7) in co-operation with the screw-formed element (3) for winding on or off the cords (4, 5) on said element upon relative mov ment between said element and said feed means, c h a r a c t e r i z e d in motor drive means (2) arrange in said rail (15) and connected to said screw-formed element (3) for rotation thereof for said winding of the cords.

2. An apparatus according to claim 1, c h a r a c t e r i z e d in that said drive means (2) con¬ sists of a motor and gearbox unit (2) including a slip coup¬ ling (19) coming into operation upon fully drawn-up blind.

3. An apparatus according to claim 1 or 2, c h a r a c t e r i z e d in that said drive means (2) also includes means (11, 12) for turning the slats between a sub¬ stantially horizontal open position and a substantially vert- ical closed position.

4. An apparatus according to any of the preceding claims, c h a r a c t e r i z e d in guide means (1 , 10) for said winding of the cords (4, 5) on and from said screw-formed ele ment (3) .

5. An apparatus according to any of the preceding claims, c h a r a c t e r i z e d in two feed means (6, 7) arranged at a distance from each other, said feed means being moved in the same direction along said screw-formed element (3) upon the rotation thereof.

6. An apparatus according to claims 4 or 5, c h a r a c t e r i z e d in that said guide means (1, 10)

^■ . consists of a guide roller (1) arranged at one (6) of said feed means and a guide roller (10) fixed to the rail (15) .

7. An apparatus according to any of the preceding claims, c h a r a c t e r i z e d in that said screw-formed element

(3) consists of a screwed shaft.