A ROTATION BLOCKING MECHANISM FOR ROLLER BLINDS

Abstract: In traditional roller blinds the blocking is released by a short pull in the bottom edge part whereby gravity frees the blocking element. This requires manual skills in order to avoid erratic handling. According to the invention the release may occur positively in that the blocking element is released by means of an operating cord or chain (S) which activates those arms (A) which already connect the chain wheel to the roller blind roller.

Description: A rotation blocking mechanism for roller blinds. The invention relates to a blocking mechanism for a roller blind of the type in which, under certain conditions of rotational speed, one out of a number of balls is wedged between an inner part and an outer part and comprising a flexible pulling element at one end of the roller blind. Roller blinds are of two main types. The first has a manual pull in the lower edge part so that a spring inside the roller blind roller is tightened when the blind is pulled down. This is a self-raising roller blind. When the roller blind is at rest raising is blocked by an element which locks the rotating outer part to the fixed innner part of the roller. Such elements are presently frequently balls which are carried in pockets in the rotating outer part. When the roller blind is to be raised again the lower edge part has to be pulled, and it must be quickly released, in order that the wedged-in ball is released, and the roller blind must under the influence of the spring obtain such a great rotational speed that all balls remain in the pockets in the outer part. The other type is activated by pulling an endless ball chain at one end of the roller blind. A pull in one direction causes raising against gravity, and the ball chain must be blocked when the roller blind has the correct position. Lowering is performed by releasing the blocking and braking against gravity. It may be desirable to combine the two constructions, so that the spring force only compensates for the wheight of the more or less lowered roller blind, in order that lowering as well as raising is performed by a pull in the ball chain. However it may also be desirable to retain the self-raising feature with lowering by means of the ball chain. In this case, however, it is a problem that release by pulling the ball chain in similarity to pulling the lower edge part does not function reliably. This gives the user an insecure feeling compared to the traditional solution using a pull in the lower edge part. This means that an important possibility for building-in the roller blind is made more difficult. It is the purpose of the invention to improve a blocking mechanism of the kind mentioned at the top so that the mentioned disadvantages do not appear. This is obtained in a construction which is particular in that pulling the flexible pulling element operates an element which is capable of pushing out a wedged-in ball so that the outer part may rotate relative to the inner part. This is a general release device which may also be used in conjunction with traditional lowering by a pull in the lower edge part. In order to obtain operation by means of an endless ball chain and lowering by pulling in one direction in the ball chain and release in the other direction an advantageous embodiment has been provided which is particular in that the chain wheel for the ball chain has a number of axially protruding arms in a number which corresponds to the number of balls which by pulling the ball chain in one direction establishes a link between the the chain wheel and the roller blind roller and by pulling the ball chain in the other direction releases the ball which is presently wedged-in. In order to enable the construction of a roller blind with in which the end at which operation is performed may be chosen at will, the axially protruding parts are provided with symmetrically placed release surfaces on the axially protuding arms. The invention will be described in greater detail in the following with reference to the drawing, in which Fig. 1 shows the end of a roller for a roller blind with a chain wheel and chain guide, Fig. 2 in perspective shows a chain wheel and surrounding elements according to the invention, Fig. 3a shows an axial section in the locking mechanism in the released state, and Fig. 3b shows an axial section in the locking mechanism in the blocked state. Fig. 1 shows the internal mechanism in a roller for a roller blind with operation control on the left side. It consists of a rod 1, around which a raising helical spring which is not shown may be placed, so that one end is connected to the bushing 2, and the other end to the ende of the rod 1. The rod 1 is non-rotating, in that it is provided with an insert 3 which is secured against rotation by insertion into a bracket. The insert 3 furthermore ensures that that a shield 4 for a pull cord also remains non- rotating. The roller which is not shown wil rotate around the stationary rod 1, in that the bushing 2 constitutes a bearing. By operating the roller blind by means of a pull cord or a ball chain, the pull in the cord must be transferred to the bushing, and this occurs in that the cord is placed around a cord pulley or chain-wheel 5 which in a suitable manner establishes a connection to the bushing 2. At S it is indicated how a pull cord or ball chain is registering with the chain wheel 5. In Fig. 2 some of the same elements is shown in larger scale. The shield 4 is provided with two large openings 8 and 9 which permit a large deviation angle for the operating cord. The chain wheel 5 is placed rotatably on the part 6 and has three arms A which engages the bushing 2. The directions S show how the cord or the ball chain mesh with the chain wheel 5. The arms A have a particular cross section which make the invention operational. In Fig. 3a a cross section of the bushing 2 is seen which may rotate around the part 6 on the rod 1. Only one ball is shown, in the pocket 1 1, but in practical use there will also be balls in the pockets 12 and 13. The ball is flung against that part of the pocket which is most remote from the axis of rotation, and for this reason it does not create any blocking. Driving from the chain wheel 5 occurs by engagement of the arms A in corresponding hollows B in the bushing 2. In Fig. 3b corresponding cross section as in Fig. 3a is seen, only the ball forms its blocking function. The ball 10 is wedged between the left edge of the pocket 1 1 and the right edge of the depression 7. The invention is brought into action by a pull in the ball chain, so that the flange A' on the arm A pushes the ball 10 out of engagement between the edge 11 of the pocket and the depression 7. In the figure this corresponds to a clockwise rotation of the cord pulley 5 with the arms A mentioned. It will be noted that the arms A have a symmetrical cross section with two similarly made flanges A' which means that the chain wheel 5 may be made in one piece and still be used for operation from the left side or from the right side, in that there will be a flange A' available in both situations for acting on a blocking ball

Claims: PATENT CLAIMS 1. A blocking mechanism for a roller blind of the type in which, under certain conditions of rotational speed, one out of a number of balls is wedged between an inner part and an outer part and comprising a flexible pulling element at one end of the roller blind characterised in that pulling the flexible pulling element operates an element (A') which is capable of pushing out a wedged-in ball (10) so that the outer part (2) may rotate relative to the inner part (1). 2. A blocking mechanism according to claim 1, characterised in that the flexible element is an endless ball chain and in that the chain wheel (5) has a number of axially protruding arms (A, A') in a number which corresponds to the number of balls (10) which by pulling the ball chain in one direction establishes a link between the the chain wheel (5) and the roller blind roller and by pulling the ball chain in the other direction releases the ball (10) which is presently wedged-in. 3. A blocking mechanism according to claim 2, characterised in that the axially protruding parts are provided with symmetrically placed release surfaces (A') on the axially protuding arms (A).

Inventors: RASMUSSEN KEN, RASMUSSEN, KEN
Applicants: CHR FABERS FABRIKER A S AS, RASMUSSEN KEN, A/S CHR. FABERS FABRIKER A/S, RASMUSSEN, KEN
Application year: 1999
Main classification: E06B9
IPC codes: E06B9