Device for transmitting a drive force between a flexible element and a rotatable body

Abstract: A device for transmitting a drive force between a flexible element (1), such as cord, and a first rotatable, cylindrical body (2), said flexible element (1) is trained around the casing surface of the body through a pre-determined angle, wherein a second cylindrical body (2') is arranged with a rotating shaft parallel to that of the first, along which the flexible element is trained in opposing direction, said both bodies, preferably provided with at least one groove (10) for receiving said flexible element (1), are embodied and/or placed such that the bodies rotate without slippage between flexible element (1) and both cylindrical bodies (2,2').

Description: The invention relates to a device for transmitting a drive force between a flexible element, such as cord, and a first rotatable cylindrical body, wherein the flexible element is trained through a pre-determined angle about the casing surface of the first cylindrical body in one direction and a second cylindrical body is arranged with its rotating shaft in parallel to that of the first cylindrical body, around which the flexible element is trained in an opposite direction, and wherein both bodies are placed such that the space between the cylindrical bodies is smaller than the thickness of the flexible element so clamping the flexible element therebetween. Such a device disclosed in EP-A-0 127 107, is known for example as a winch, wherein the rotatable body is the drum and the flexible element a belt or the like. The force transmission takes place through friction between both elements at the point of the turnover angle. Another embodiment has pulleys with the ropes associated therewith. The invention has for its object to provide a device wherewith a flexible element, preferably in the form of a cord, can be used in relatively small embodiments, particularly suitable for the driving of cords in sunblinds and the like. The device must occupy little space therein in view of the limited space and must have a wholly non-slip action since otherwise, in the case of double embodiments, there occurs a relative shifting between the flexible elements and the curtains for controlling will therefore go out of square. The device according to the invention is distinguished in that at least one of the cylindrical bodies is provided with one or more grooves each of which for receiving a flexible element, wherein the passage of the groove is smaller than the thickness of the flexible element. Owing to the use of the grooves in the two cylindrical bodies, in which the flexible element is trained through a narrow passage no slip will occur with respect to the wheel that is driven or to be driven. Thereto the cylindrical bodies also serve as clamping members for increasing the permissible force to be transmitted without slip occurring. In a preferred embodiment each cylindrical body is provided with a gear wheel rim belonging to a transmission, which rims preferably engage each other directly. The required rotation direction of the cylindrical bodies is herewith brought into conformity with the path of the flexible element, wherein moreover notably little space is required. According to a further development of the invention the groove for receiving the flexible element is V-shaped, so a self-clamping action is obtained in the groove through the tension of the flexible element, whereby the force for transmission can also be increased without slip occurring. Furthermore the groove in at least one of the gear wheel rims can be positioned with respect to the periphery of the confronting gear rim such that the passage space bounded between the mutually engaging theeth of the confronting gear wheel rims is smaller than the thickness of the cord, whereby an additional clamping action takes place at at least two points (depending on the depth and shape of the at least one groove) on the periphery of the flexible element. This clamping action ensures a shaggered deforming of the flexible element which gives an extra assurance against undesired slippage between the flexible element and the cylindrical bodies. A groove can also be provided in each of the opposing gear wheel rims. Each of the above measures can be applied separately or be used in any combination. Above mentioned and other features will be further elucidated in figure description below of a number of embodiments. In the drawing: fig. 1 shows a schematic perspective view of a transmission device according to the invention used with a single curtain and provided with three cylindrical bodies with two flexible elements, fig. 2 shows a view corresponding with fig. 1 of a device according to the invention employed with a double curtain, fig. 3 shows a front view of the device of fig. 1 and 2 respectively on an enlarged scale, fig. 4 is a side view of the device of fig. 3, fig. 5 shows a front view of an alternative embodiment of the device in fig. 3, fig. 6 shows an alternative embodiment of the device of fig. 1 and 3 respectively, wherein the cylindrical bodies are provided with a gear wheel rim along which the flexible element is guided, fig. 7 is a top view of the device of fig. 6, fig. 8 and 9 show respectively a transverse and lengthwise section of a portion of the device of fig. 6 on an enlarged scale. The device for transmitting a drive force between a flexible element and a cylindrical element is shown as used in a sunblind as according to fig. 1 or 2. The flexible element 1 is used herein as drive element for opening and closing a folding curtain. To this end the flexible element 1 is trained around three cylindrical bodies 2, the middle one 2′ of which is provided with a central space 3 for receiving an end 4 of an operating handle 5 fitting therein. The flexible element 1 is trained around the rolls 2 in zigzag fashion such that a cord 1 lies against the central cylindrical body 2′ through at least 180°, see fig. 3. The guiding of the respective cords 1 and 1′ in fig. 1, co-acting with reversing wheels 6 is such that, when the ends are fastened in the lower beam 7 of the folding curtain, they move up and down, when the wheels 2 turn, in the direction of the arrow P₁ depending on the rotation direction of the handle 5. The cord guiding is known and falls further outside the scope of the invention. Likewise employed in fig. 2 are two cords 1 and 1′ which are used for moving up and down the lower beam 7′ and upper beam 7″ respectively of the upper and lower curtain respectively, wherein through the rotation of the wheels 2 the cords 1 and 1′ are guided and moved such that these beams will begin to move up and down according to the arrows P₁ for simultaneous closing and opening of the window. From the application it will be apparent that a non-slip transmission of forces between the wheels 2 and the cords 1 is necessary, since the beams 7, 7′, 7″ otherwise respectively move up and down unevenly. In order to effect the non-slip transmission three cylindrical rolls 2 are arranged adjacent to each other, as already stated above. The distance between the casing surfaces of the rolls 2 is such that this is smaller than the thickness of the cord 1, thus resulting in a clamping action between the casing surfaces of adjacent rolls on the flexible element. In addition to the relatively large turnover angle around the middle roll 2′ the cord 1 also obtains a clamping action at two points in order to prevent undesired slippage. Further the casing surface of at least one of the rolls, for example roll 2′ is provided with V-shaped grooves 10, in each whereof is received a cord 1 and 1′ respectively. As a result of the tensile stress in the cords the V-shape of the groove causes a gripping action on the cord, which will likewise prevent slippage. If necessary it can be required to arrange not three but five cylindrical bodies adjacent to each other, as shown in fig. 5. The number of clamping points on the cord is herein increased to four while the turnover angle around the cylindrical bodies is three times 180°, wherein it can be assumed that the middle rolls are each driven at a speed such that the peripheral velocity of the casing surface is equal to that of the cord. The driving of three cylindrical bodies can be simplified by providing these with a gear wheel rim 12, which is shown in fig. 6. The gear wheel rims 12 of the cylindrical bodies 2 lying mutually adjacent engage each other and ensure a mutually non-slidable position of the cylindrical bodies. The cord 1 can be trained around the cylindrical bodies 2 in accordance with the embodiment according to fig. 3. The cord 1 can be trained around cylindrical casing surfaces in addition to the gear wheel rim, which surfaces are provided with grooves as according to fig. 4. It is also possible however to arrange the V-shaped groove 14 in the gear wheel rims 12 themselves, which is shown in fig. 7, whereby the axial length of the cylindrical bodies can be limited considerably. In all embodiments the V-shaped grooves are dimensioned such that the passage space bounded by the mutually engaging teeth of the gear wheel rims 12 is smaller than the thickness of the cord 1, see fig. 8, but in the device according to fig. 6-9 an extra clamping action takes place at four points on the periphery of the flexible element 1. This clamping action ensures a staggered deforming of the flexible element 1, as in fig. 9, which gives an extra assurance against undesired slippage between the flexible element 1 and the cylindrical bodies 2. The invention is not limited to the embodiments described above. Diverse variations and combinations of the above described features are therefore possible. The device according to the invention is moreover described as a device for transmitting a force from a cylindrical body to a cord. The reverse hereof, a driven cord 1 transmitting forces to a group of cylindrical bodies consisting of at least two elements, is of course also possible.

Claims: Device for transmitting a drive force between a flexible element (1), such as cord, and a first rotatable cylindrical body (2), wherein the flexible element is trained through a pre-determined angle about the casing surface of the first cylindrical body in one direction and a second cylindrical body (2′) is arranged with its rotating shaft in parallel to that of the first cylindrical body (2), around which the flexible element (1) is trained in an opposite direction, and wherein both bodies (2, 2′) are placed such that the space between the cylindrical bodies is smaller than the thickness of the flexible element so clamping the flexible element therebetween, characterized in that at least one of the cylindrical bodies (2, 2′) is provided with one or more grooves (10, 14) each of which for receiving a flexible element (1), wherein the passage of the groove (14) is smaller than the thickness of the flexible element (1). Device as claimed in claim 1, characterized in that each of the cylindrical bodies has a gear wheel rim (12) and the groove (14) is recessed into the gear wheel rim. Device as claimed in claim 1 or 2, characterized in that the groove (10, 14) is V-shaped. Device as claimed in any of the previous claims 1-3, characterized in that at least one of the cylindrical bodies (2, 2′) is provided with a central recess (3) for receiving a control member (5) such as a hand crank. Device as claimed in claim 4 wherein each flexible element is a cord of a sunblind.

Inventors: SCHOEN SIEGFRIED JOACHIM, SCHOEN, SIEGFRIED JOACHIM, Schön, Siegfried Joachim
Applicants: SCHOEN BV, SCHOEN B.V.
Application year: 1990
Main classification: E06B9
IPC codes: E06B9