Abstract:
A window blind, with a winding shaft having a rolling-up device, a blind web rolled up on the winding shaft, a pull bar, to which the free end of the blind web is fastened, a guide arrangement, on which the end regions of the pull bar are arranged longitudinally displaceably perpendicularly to the pull bar axis, and a braking arrangement which is arranged inside the pull bar and acts releasably on the guide arrangement in order to fix the pull bar in any positions on the guide arrangement.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a window blind with a winding shaft having a rolling-up device, a blind web rolled up on the winding shaft, and a pull bar, to which the free end of the blind web is fastened.  
           [0002]    Window blinds of the type referred to, which serve as protection against the sun, particularly in vehicles, are generally designed as roller blinds and are correspondingly costly. Even more costly are electric motor-operated window blinds which also belong to the state of the art.  
         SUMMARY OF THE INVENTION  
         [0003]    The object of the invention is to provide a window blind, in which the blind web can be drawn off the winding shaft and transferred into the sun protection position desired in a simple manner and locked, in particular a cost-effective design being sought.  
           [0004]    Accordingly, the subject of the invention is a window blind with a winding shaft having a rolling-up device, a blind web rolled up on the winding shaft, a pull bar, to which the free end of the blind web is fastened, a guide device, on which the end regions of the pull bar are arranged longitudinally displaceably perpendicularly to the pull bar axis, and a braking arrangement which is arranged inside the pull bar and acts releasably on the guide arrangement in order to fix the pull bar in any positions on the guide arrangement. In this connection, the guide device preferably comprises two hollow profile strips which flank the blind web at its longitudinal edges and are each provided with a longitudinal slot on their mutually facing sides. However, rods, for example made of round material, can also be used instead of hollow profile strips. It is of great importance that closing bodies be inserted into the free ends of the pull bar. These engage in one of the longitudinal slots. Each slot has an opening with a brake block inserted in it, which is loaded by a compression spring. The brake blocks are arranged such that they can, via an adjustable connecting means, be moved toward one another counter to the force of the compression spring for canceling the braking action. As a rule, the brake blocks are located in pressing contact against the inner wall of the hollow profile strips, and this pressing contact is interrupted temporarily only for adjusting the blind web position.  
           [0005]    Especially advantageously, the adjustable connecting means comprises a tautly guided wire cable which is fastened to the brake blocks and is supported by supports arranged at a spacing from one another. An actuating means acts on the wire cable arranged between the supports, and when that means is operated, it shortens the active length of the wire cable and draws the brake blocks toward one another. In this connection, the actuating means preferably comprises a manually operable lever which is articulated on the pull bar and supported on the wire cable by a working surface designed as an eccentric path.  
           [0006]    In a development of the invention, the pull bar has a handle with a handle opening, in which the lever serving as the actuating means is arranged.  
           [0007]    The invention also concerns a window blind with a winding shaft having a rolling-up arrangement, a blind web rolled up on the winding shaft, a pull bar, to which the free end of the blind web is fastened and a guide arrangement, on which the end regions of the pull bar are arranged longitudinally displaceably perpendicularly to the pull bar axis. The guide arrangement comprises two racks flanking the blind web at its longitudinal edges and two toothed wheels which mesh with the racks, and which are arranged in the end regions of the pull bar. At least one braking arrangement fixes the pull bar in any positions on the guide arrangement. The at least one braking device can act on one of the toothed wheels or a bearing shaft bearing a toothed wheel.  
           [0008]    According to a preferred embodiment, the pull bar is provided in each end region with a bearing housing in each case surrounding a rack. Each bearing housing bears a toothed wheel arranged in a rotationally fixed manner on a bearing shaft. At least one of the bearing shafts is, for braking the restoring movement of the rolling-up arrangement, equipped with a friction brake which consists of a shaped body made of wear-resistant, viscoplastic synthetic material which is arranged in the bearing housing in a rotationally fixed manner in relation to the bearing shaft. The body has a bore for receiving an axial region of the bearing shaft. The diameter of the bore is smaller than the diameter of the bearing shaft, but sufficient to permit relative movement between the shaped body and the bearing shaft.  
           [0009]    According to another preferred embodiment, a brake block loaded in each case by a compression spring in each case acts on untoothed circumferential regions of the toothed wheels. The arrangement of the brake blocks is effected in such a manner that they can, via an adjustable connecting means, be moved toward one another counter to the force of the compression spring, while canceling the braking action. The adjustable connecting means comprises a tautly guided wire cable which is fastened to the brake blocks and is supported by supports arranged at a spacing from one another. An actuating means acts on the wire cable arranged between the supports in order, when it is operated, to shorten the active length of the wire cable and to draw the brake blocks toward one another.  
           [0010]    It is especially advantageous if the adjustable connecting means comprises a tautly guided wire cable which is fastened to the brake blocks and is supported by supports arranged at a spacing from one another. An actuating means acts on the wire cable arranged between the supports so that when it is operated, it shortens the active length of the wire cable and draws the brake blocks toward one another. The actuating means preferably comprises a manually operable lever which is articulated on the pull bar and supported on the wire cable by a working surface designed as an eccentric path. In this connection, the pull bar has a handle with a handle opening, in which the lever serving as actuating means is arranged.  
           [0011]    According to a further preferred embodiment of the invention, at least one of the toothed wheels has, in addition to the toothing meshing with the rack, an external toothing. A braking body under the influence of a compression spring can be engaged in the tooth spaces. By means of a manually operable slide, the braking body disengaged again counter to the force of the compression spring.  
           [0012]    In order to compensate possible dimensional differences of the spacing between the racks and the bearing housings, it is advantageous that at least one of the bearing housings is loaded outwardly, that is to say in the direction of a rack, by a compression spring.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    Illustrative embodiment of the invention is explained in greater detail below by means of the drawings, in which  
         [0014]    [0014]FIG. 1 shows a view of a complete window blind,  
         [0015]    [0015]FIG. 2 shows a part region of the window blind in vertical section,  
         [0016]    FIGS.  3 - 8  show embodiments and details of a guide arrangement of the window blind according to FIGS. 1 and 2,  
         [0017]    [0017]FIG. 9 shows a view of a second complete window blind,  
         [0018]    [0018]FIG. 10 shows a part region of the window blind according to FIG. 9 in vertical section,  
         [0019]    [0019]FIG. 11 shows a part region of the window blind according to FIG. 9 in horizontal section,  
         [0020]    [0020]FIG. 12 shows a view of a third complete window blind,  
         [0021]    [0021]FIG. 13 shows a part region of the window blind according to FIG. 12 in vertical section,  
         [0022]    [0022]FIG. 14 shows a view of a fourth complete window blind, and  
         [0023]    [0023]FIG. 15 shows a part region of the window blind according to FIG. 14 in vertical section. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0024]    The novel window blind according to FIGS.  1 - 8  comprises a winding shaft  1 , a blind web  2  arranged so as to be capable of being rolled up on and unrolled from the shaft, a pull bar  3 , to which the free end of the blind web  2  is fastened, and a guide arrangement formed from two hollow profile strips  4  flanking the blind web  2  at the longitudinal edges.  
         [0025]    The winding shaft  1  suitably comprises a tube with closing elements  5  at the ends, pivots  6  and, arranged in its interior, a rolling-up device with a spring  7  indicated in only a dot/dash manner.  
         [0026]    On their mutually facing sides, the hollow profile strips  4  each have a longitudinal slot  8  which, as shown in FIGS.  3  to  5 , can be of very different design. The hollow profile strips  4  can thus be in the form of a U-shaped profile according to FIG. 3, a slotted box profile according to FIG. 4 or a slotted tubular profile according to FIG. 5. FIG. 6 shows another variant, a solid round profile  9  forming the guide arrangement.  
         [0027]    [0027]FIG. 2 shows a section through one of the hollow profile strips  4  and through the pull bar  3  which likewise consists of a hollow profile and is preferably in the form of a decorative profile strip. The right half, which is not shown in FIG. 2, is of mirror-inverted design relative to the left half, which is shown. A closing body  10 , which has a stepped bore and a passage opening  11 , is inserted into each end of the pull bar  3 . The first step  12  of the stepped bore receives a brake block  13 , and the second step  14  receives a compression spring  16  loading the brake block  13  against the inner wall  15  of the hollow profile strip  4 . The brake blocks  13  loaded by the compression spring  16  hold the pull bar  3  along with the blind web  2  in any position on the hollow profile strips  4  of the guide arrangement. As seen in FIG. 2, adjustable connecting means enable the brake blocks  13  to be moved toward one another, counter to the force of the compression springs  16 , while canceling the braking action. A preferably sheathed wire cable  17 , which is guided through the passage openings  11  in the closing bodies  10 , is fastened to the brake blocks  13  and runs tautly through the pull bar  3 . It serves as the adjustable connecting means. Approximately at the central region, the wire cable  17  is supported by two supports  18  which may consist of pins and are spaced from one another.  
         [0028]    Between the supports  18  is an actuating means for acting on the wire cable  17 . That means comprises a lever  20  articulated on the pull bar  3  at  19 . The working surface of the lever  20  on the wire cable  17  follows an eccentric path  21 , so that the wire cable  17  is moved into the space between the supports  18  when the lever  20  is pivoted in the arrow direction  22 . This shortens the extended wire cable length and moves the brake blocks  13  toward one another which pulls them away from the inner wall  15  of the hollow profile strips  4 , temporarily interrupting their braking action. The lever  20  is suitably arranged in the handle opening  23  of a handle  24 . The handle  24  can be grasped by a human hand. It is possible to operate or pivot the lever  20  using, for example, the thumb of the human hand. To roll up or unroll the blind web  2  in any position, the user holds the handle  24  and cancels the braking action of the brake blocks  13  by actuating the lever  20 . After the lever  20  is released, it automatically pivots back into its starting position due to the tension in the wire cable. In FIG. 2, the starting position of the lever  20  and of the wire cable  17  is shown by solid lines, and the lever actuation position is illustrated by dot/dash lines.  
         [0029]    [0029]FIG. 6 shows that the closing bodies  10  can also be designed for surrounding solid profiles, such as round bars, without departing from the principle of the invention.  
         [0030]    For clarification, FIGS. 7 and 8, are on an enlarged relative to FIGS.  1  to  6 . FIG. 7 shows the window blind with a braking system in the closed state, and FIG. 8 shows the window blind with a braking system in the open state.  
         [0031]    In the window blinds shown in FIGS.  9  to  15 , those parts corresponding to the window blinds according to FIGS.  1  to  8  are provided with the same reference numbers. The window blind of FIGS.  9  to  11  thus comprises a winding shaft  1 , a blind web  2  arranged so as to be capable of being rolled up and unrolled thereon, a pull bar  3 , to which the free end of the blind web  2  is fastened, and a guide arrangement which comprises two racks  30  flanking the blind web  2  at its longitudinal edges and two toothed wheels  31  which mesh with the racks and are arranged in the end regions of the pull bar  3 .  
         [0032]    [0032]FIG. 10 shows a section through one of the end regions of the pull bar  3 . There is a bearing housing  32  which is inserted into this pull bar end for mounting a bearing shaft  33 , a toothed wheel  31  and a shaped body  34 . As can be seen, the toothed wheel  31  meshes with the toothing of the rack. This also occurs with the second toothed wheel  31  located at the other pull bar end and the associated toothing of the second rack  30 , so that the pull bar  3  cannot tilt when the blind web  2  is drawn down from the winding shaft. Dimensional differences can be compensated by a spring  35  acting on one bearing housing  32 .  
         [0033]    [0033]FIG. 11 shows that the bearing shaft  33  bears not only a toothed wheel  31  connected to it in a rotationally fixed manner but also the above-mentioned shaped body  34  which serves as a friction brake and consists of a wear-resistant, viscoplastic synthetic material, such as a thermoplastic polyester elastomer. The shaped body  34  has a bore for receiving an axial region of the bearing shaft  33 , and the opening cross section of the bore is smaller than the cross section of the bearing shaft  33 , so that the bearing shaft is located in the bore in the manner of a press fit. The press fit is nevertheless selected in such a manner that a relative movement between the shaped body  34  and the bearing shaft  33  is still possible, and locking of the blind is brought about by matching the spring force of the rolling-up device and the shaped bodies  34 .  
         [0034]    The window blind according to FIGS. 12 and 13 has a similar construction to that according to FIGS.  1  to  8 , so that the same reference numbers are once again to serve for corresponding parts here. Instead of the hollow profile strips  4  and closing element  5  provided in the window blind according to FIGS.  1  to  8 , the window blind of FIGS. 12 and 13 has guide arrangements which, corresponding to the window blind according to FIGS.  9  to  11 , comprise two racks  30  flanking the blind web  2  at its longitudinal edges and two toothed wheels  31  which mesh with the racks and are arranged in the end regions of the pull bar  3 .  
         [0035]    Inserted into the pull bar ends are bearing housings  32  which each serve for mounting a bearing shaft  33  and a toothed wheel  31  and each housing, as shown in FIG. 11, surround a rack  30 . The toothed wheels  31  each have a toothed circumferential region which interacts with the respective rack  30  and moreover the wheels  31  have an untoothed circumferential region  36 , which interacts with brake blocks  13 . The design of the braking arrangement, the functioning of the brake and also the canceling of the braking action for adjusting the blind web  2  correspond exactly to the embodiment according to FIG. 2, described above.  
         [0036]    In the window blind according to FIGS. 14 and 15, parts corresponding to the embodiments described have been provided with corresponding reference numbers. In FIGS. 14 and 15, at least one of the toothed wheels  31  is provided with an external toothing  38  in addition to the toothing  37  meshing with the rack  30 . A braking body  40  under the influence of a compression spring  16  engages in the tooth space  39  of the toothed wheel  31 . By means of a manually operable slide  41 , the body  40  can be disengaged again counter to the force of the compression spring  16 .  
         [0037]    The invention is not limited to the illustrative embodiments shown, but also comprises all similarly operating embodiments in accordance with the invention. The invention is not limited to the specific combinations of features in each embodiment, but it can also be defined by any combinations of specific features from all the individual features disclosed, and any individual feature can be omitted or can be replaced by at least one individual feature disclosed at another place.  
         [0038]    Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.