WO2001000959A1

WO2001000959A1 - Braking arrangement for roller blinds

Info

Publication number: WO2001000959A1
Application number: PCT/DK2000/000340
Authority: WO
Inventors: Kim Rysholt
Original assignee: A/S Chr. Fabers Fabriker
Priority date: 1999-06-23
Filing date: 2000-06-23
Publication date: 2001-01-04
Also published as: AU5521700A

Abstract

Roller blinds for inclined mounting create a pending bulge in the lowered condition and have a tendency to wind too fast, in particular when a strengthened spring is used in order to reduce the bulging. According to the invention both good stretching and quiet winding are obtained when a strengthened spring is combined with two brakes: one brake which is velocity dependent and fitted in the roller blind rod, and a brake which is based on friction and which acts directly on the roller blind.

Description

Braking arrangement for roller blinds.

The invention concerns a braking and blocking arrangement for roller blinds, in particular for use in an inclined mounting, comprising a winding mechanism and means for retaining the roller blind in an optional position.

Conventional blocking of roller blinds takes place by blocking the winding by means of a mechanism inside the roller blind rod. The driving spring retains its tension, but it is held by pawls or balls, and the lower rail provides a stretched condition in vertically-hung roller blinds. In the case of inclined mounting of the roller blind, such as in the case of windows in an inclined roof, it is required to guide the roller blind so that it stays parallel to the window, and the force of gravity is not sufficient to keep it stretched. In smaller roller blinds this problem has been solved thereby that that the roller blind rod does not contain any blocking means but a tensioned spring which serves to maintain the roller blind stretched. The lower edge of the roller blind may be hung into pockets in the window frame. Thereby it is not obtained that the roller blind may be pulled down to an optional degree. This is, however, obtained in another construction where strong clamps at either end of the lowest slat grip guide rails mounted at the sides of the window frame. Unless the lowest slat is guided by hand, releasing the clamps will cause a very fast and uncontrolled winding of the roller blind because the spring is more tensioned than in conventional roller blinds.

It is the purpose of the invention to eliminate the described disadvantages and to obtain a roller blind which is suited for inclined mounting and which permits both automatic and well-controlled winding and a tensioned disposition in a blocked position. This is obtained by a construction according to the invention which is particular in that it comprises braking means of two types, a first type which is velocity dependent and which is disposed inside the roller blind rod and a second type which is independent of velocity and which is disposed in conjunction with the side edges of the roller blind. A suitable balancing of the braking effect of the two brakes will ascertain that a strong spring may be mounted without causing an uncontrolled winding, and the roller blind may be held stretched during the winding, also dynamically.

According to an advantageous embodiment of the invention the velocity dependent braking means are constituted by a cylinder for air with a piston which is acutated by means of a nut and a calibrated exhaust vent, and the velocity independent means are constituted by friction-creating slide blocks which create friction against guide rails along the edges of the roller blind. An advantageous placement is at the ends of the lowest slat of the roller blind.

According to a further advantageous emobidiment of the invention the velocity- independent means are constituted by the friction of the edge parts of the roller blind against the guide rails. Hereby there is obtained a somewhat changed interaction between the velocity dependent and the velocity-independent braking effect, in that the roller blind close to its totally wound position will be pulled upwards by a spring force which is reduced with respect to a lower position, and in compensation the friction is reduced, because a much smaller part of the edge parts of the roller blind are in frictional contact with the guide rails.

According to a further advantageous embodiment of the invention blocking is obtained in an optional position, in that the velocity-independent braking means may be re-arranged for blocking. This may occur by the extraction of a wedge so that a clamp closes or by means of a harder wedging-in of the friction-creating elements, e.g. the slide blocks mentioned above or by increasing the cross dimension of the slide blocks, in the case of U-shaped guide rails.

An alternative possibility for clamping is obtained in an embodiment which is particular in that re-arrangement for blocking occurs by clamping the guide rails about the edge parts of the roller blind.

The invention will be described in detail in the following with reference to the drawing, in which Fig 1 shows a slanted mounting of a roller blind from the side in the pulled condition with an indication of a normal position with an ordinary spring tension as well as with a stronger spring as a consequence of the invention, and

Fig. 2 shows velocity diagrams for winding of roller blinds with different braking means.

In Fig 1 is an edge view of a roller blind in inclined position which corresponds to a window which is fitted into an inclined roof Modern roof windows may be mounted in a wide range of roof pitches, and the figure shows at a) how a fitted roller blind creates a downwards hanging bulge when it only stretched by an ordinary winding spring. By means of a stronger winding spring which is controlled according to the invention, the bulge is considerably reduced, as shown at b)

In Fig. 2 is seen the relationship between the height of the lower edge of a roller blind during automatic winding from the lowest position and the velocity of the lower edge. At a) is is seen that the velocity is increasing during the entire process, even if the acceleration decreases towards the end of the movement when the lower rail hits the upper part of the mounting of the roller blind The movement is abruptly stopped, and the energy stored during the movement is released with a heavy noise and wear. At b) is shown the development of the velocity during a corresponding winding using braking and blocking means according to the invention. After an acceleration which due to the higher spring tension is somewhat larger in the beginning, the velocity stabilises at a far lower value which does not entail wear or noise.

The dynamic or velocity dependent braking may advantageously be obtained by means of a piston which due to the rotation of the tubular roller blind rod is brought from one position in an air cylinder to another by means of a nut and a thread on the piston rod. In case the mass of the air is unchanged during the process, there will be developed an over- or underpressure which provides a spring effect and which due to larger forces in the moving parts may increase the friction in the mechanism so that a braking is obtained, but a more precise control of the movement is obtained by establishing a controlled venting of the air which is influenced When the vent used is small, a velocity dependent braking will be obtained with great precision, in a given velocity interval. The vent may be established in various ways, including by fitting previously calibrated nozzles or with a possibility for fine adjusment in conjunction with the installation of a roller blind. In combination with a fixed friction the roller blind may be held stretched at all times during winding, because the spring force for the stretching will be available the whole time.

Claims

PATENT CLAIMS

1. A braking and blocking arrangement for roller blinds, in particular for use in an inclined mounting, comprising a winding mechanism and means for retaining the roller blind in an optional position, characterised in that it comprises braking means of two types, a first type which is velocity dependent and which is disposed inside the roller blind rod and a second type which is independent of velocity and which is disposed in conjunction with the side edges of the roller blind

2. A braking and blocking arrangement according to claim 1, characterised in that the velocity dependent braking means are constituted by a cylinder for air with a piston which is acutated by means of a nut and a calibrated exhaust vent, and the velocity independent means are constituted by friction-creating slide blocks which create friction against guide rails along the edges of the roller blind.

3. A braking and blocking arrangement according to claim 2, characterised in that the slide blocks are fitted at the end of the lower rail of the roller blind.

4. A braking and blocking arrangement according to claim 1, characterised in that the velocity-independent means are constituted by the friction of the edge parts of the roller blind against the guide rails.

5. A braking and blocking arrangement according to any of the above claims, characterised in that blocking is obtained in an optional position, in that the velocity-independent braking means may be re-arranged for blocking.

6. A braking and blocking arrangement according to claim 5, characterised in that re-arrangement for blocking occurs by clamping the guide rails about the edge parts of the roller blind

7. A braking and blocking arrangement according to claim 5, characterised in that re-arrangement for blocking occurs by increasing the crosswise dimension of the slide blocks.