Abstract:
A telescopic tube joint ( 1 ) is provided for vacuum cleaner suction tubes or for tripods having at least one outer tube ( 2 ) and at least one inner tube ( 3 ). The tube joint includes a catch recess ( 5 ) in the inner tube ( 3 ), a catch element ( 8 ) on the outer tube ( 2 ) which are lockable or unlockable via a manually actuated, rotably movable slider ( 11 ) which moves the catch element ( 8 ) through an opening ( 10 ) in the outer tube ( 2 ). The catch recess in the inner tube ( 3 ) consists of a tooth strip ( 6 ) provided with a plurality of teeth ( 5 ) , formed on the outer peripheral surface of the inner tube ( 3 ). The catch element consists of a short toothed rack ( 8 ) having opposing teeth ( 7 ), which is pressed into force- and form-fit contact with the toothed strip ( 6 ) by the rotary slider ( 11 ) in a locked position when turned at a small angle (α).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The invention relates to a telescopic tube joint for vacuum cleaner suction tubes or for tripods having at least one outer tube and at least one inner tube. The tube joint includes catch recesses in the inner tube which couple to a catch element in the outer tube. The catch recesses are lockable or unlockable with the catch element via a manually actuated rotary slider attached to and slidably movable around the outer tube. 
         [0003]    2. Description of Related Art 
         [0004]    In a telescopic tube joint for vacuum cleaner suction tubes according to DE 195 28 814 C1 and DE 195 47 722 C1, the catch element consists of two slidable clamp bodies. The clamp bodies are at opposing acute angles opposite the longitudinal axis of the outer tube on a slanted glide plane of a guide body inserted and form-fitted in a recess of the outer tube engaging in separate catch recesses. The clamp body blocking the respective relative movement of the inner to outer tube is slidable or, in order to release this locked position, is slidable out of its catch recess along its slanted glide plane via the linearly moveable slider. Both clamp bodies are under the influence of a spring, which serves the purpose of keeping both clamp bodies in their locked position. The catch recesses consist of ducts on the outer peripheral surface running diagonally to the longitudinal axis of the tube having a calotte-shaped cross-section, in which the correspondingly rounded clamp bodies are engaged. This telescopic tube joint has proven reliable for vacuum suction tubes. In order to use such a telescopic tube joint not only for vacuum cleaners, but also for tripods, the relatively large space between the catch recesses in the inner tube, on the one hand, as well as the multitude of parts have been perceived to be disadvantageous. In particular, the shortest telescope path is determined by the relatively large space between two catch recesses. 
         [0005]    In addition, there is a multitude of different telescopic tube joints in the prior art for tripods, which lock the tubes using spring-loaded latch pins that engage through an opening of the inner tube in a row of holes in the outer tube. Here, the shortest telescope path is determined by the distance of the openings in the outer tube. 
         [0006]    In addition, there is a series of telescopic tube joints for tripods that are locked with a force-fit toggle connection. For this purpose, a lever is switched at the respective variably achievable position, which pushes the tubes having a square cross-section force-fit against one another in their locking position. This telescopic tube joint has the considerable disadvantage that only such a force can be exerted, which does not exceed the clamping force of both tubes. When an impelling force is exerted on one or both ends, these tubes tend to slide into one another because the purely force-fit connection is not able to withstand such forces. 
         [0007]    In particular for tripods and also for vacuum cleaner suction tubes, tube joints are additionally known that can be continuously adjusted, but are clamped together under frictional force into the respective position using a rotary slide. Unfortunately, the tubes of such joints can slide into one another under an impelling force exerted on one or both ends because this force-fit connection can also not be maintained by the clamping force. 
       SUMMARY OF THE INVENTION 
       [0008]    The object of the present invention is to improve a telescopic tube joint of the like for a vacuum cleaner suction tube as well as for tripods in such a manner that a virtually infinitely variable telescopic tube is guaranteed and that, using inexpensive and simple production and assembly, force-fit as well as form-fit locking of the tubes into their locked position is ensured but can simultaneously be released with just a turn of the hand. 
         [0009]    This object is met according to the invention in connection with the generic term mentioned above, by means of a tube joint that includes a catch recess in the inner tube including a tooth strip provided with a plurality of teeth imprinted or stamped on the outer peripheral surface of the inner tube, a catch element including a short toothed rack having opposing teeth, and a rotary slide. The short toothed rack may be pressed into force- and form-fit contact with the toothed strip by the rotary slide in a locked position. The pressing force on the short toothed rack can be relieved by means of a slight turn of the slide under exertion of the force of the operator, which allows the tubes to be slid relative to one another as a result of the toothed strip moving into a rebound on an inner peripheral area of the rotary slide. The sliding force of the operator causes the tooth profiles of the teeth of the toothed strip to push the tooth profiles of the opposing teeth in the toothed rack upwards into the rebound as a result of a wedge-shape in the teeth. The opposing teeth of the toothed rack “hobble” over the teeth of the toothed strip until the desired telescope expansion or insertion length has been achieved. 
         [0010]    Now, the smallest telescopic path is defined by the distance between two teeth, whereby, due to the formation of the teeth being small in area and their corresponding multitude, a virtually infinitely variable telescopic tube joint is achieved, whose steps are now determined by the tooth spaces of the relatively small teeth. Additionally, this tube joint consists of just three parts, namely a toothed strip on the outer periphery of the inner tube, the short toothed rack and the rotary slide. A spring, onto which multiple clamping elements are positioned on a slanted plane, is not necessary. Advantageously this telescopic tube joint is not only locked force-fit together, but also form-fit in the locked position, from which it cannot be released by impelling forces on the tube ends because all—and not just one tooth of the toothed strip having the same number of opposing teeth as the toothed rack determines the locking force. Assembly is simple and production economic. 
         [0011]    In addition, this telescopic tube joint allows for a sequence of multiple and not just two tubes, which is essential, in particular for tripods, and less so for vacuum cleaner suction tubes. In order to create a telescopic tube joint having three tubes, for example, on an cross-section expanded end of the inner tube that is averted to the respective outer tube, a second rotary slide is advantageous arranged on the inner tube now acting as outer tube, which interacts with one second inner tube sliding in the first inner tube and having a second toothed strip and a second toothed rack. The effect is that the diameters of the tubes are scaled down increasingly from the first outer tube to the last inner tube, which, however, naturally, carry a larger load because they are not purely force-fit, but are always immovably form-fit in their locked position. There is also an overall pleasant appearance because the rotary slide and the tubes conform, though not in their outer diameter, but rather in their circular form. 
         [0012]    An advantage is the teeth in the toothed strip and the toothed rack being of the same size, which leads not only to a clamping area of corresponding size, but also forms a form-fit corresponding contact surface. 
         [0013]    Here, the teeth in the toothed strip and in the toothed rack have straight toothing, where the teeth gripping one another achieve a large as possible contact surface. The teeth are provided with even profiles for further development of this use, which run at an angle β to the horizontal of between 30° and 90°, preferably between 60° and 90°. An angle β between 60° and 90° has proven reliable in the first test models of the telescopic tube joint because such an angle, on the one hand, results in a small telescopic path from tooth to tooth due to its steepness and, on the other hand, also ensures a sufficient locking force under exertion of impelling forces on the tube ends. Thus, the steepness of the profile angle β together with the number of teeth determines the smallest telescopic path in the tube joint according to the invention. 
         [0014]    In order to achieve a robust and wear-resistant form, the tooth profiles on the crest of the teeth are connected to one another via a radial rounding or an even flattening. Additionally advantageous are the opposing teeth being rounded convexly over the width of the toothed rack on their free ends and the tooth spaces in the toothed strip being concavely rounded over their width. Thereby, the toothed rack having convex rounding grips the crest of its opposing teeth in the concavely rounded tooth spaces in the toothed strip, which ensures a low-friction gripping in and out of the teeth with the opposing teeth. 
         [0015]    The rotary slide has an advantageous cylindrical outer form, which encompasses the tube acting as outer tube in a space-saving manner. 
         [0016]    According to a particularly advantageous further development of the invention, each rotary slide is provided with a recess on it inner peripheral surface, which corresponds to the width and length of the toothed strip extending into the opening position of the tube joint and is provided on at least one side of the recess with a continuously narrowing inner peripheral surface, which, in the locked position achieved by turning the rotary slide, presses the toothed rack with its teeth into the bases between the teeth of the toothed strip. Since, in order to achieve this pressed position only a small angle of, for example, 15° based on the opening position is required, a change in the pulled-out position of the telescope tube can be achieved quite quickly. 
         [0017]    The toothed rack is mounted in a form-fit manner in the respective outer tube. For this purpose, the toothed rack has a rectangular shape in the vertical positional view, which reaches with slight tolerance through a square opening of the same size in the outer tube. 
         [0018]    According to a particularly advantageous further development of the invention, all tubes are made of aluminum, while the rotary slide and the toothed rack advantageously consist of polyamide. Aluminum is lighter than stainless steel and allows for a more precise imprint even with the smallest of teeth for a toothed strip, which is quite difficult with stainless steel. In order to produce a precise form of the teeth on the toothed rack, polyamide has proven to be the most convenient due to its wear resistance. The rotary slide with its clip-on front ring as well as a sealing and guiding sleeve can also be made of POM or PE. 
         [0019]    The tubes are advantageous when provided with a wall thickness of 0.8 mm and an outer diameter of between 32 mm and 38 mm. 
         [0020]    An embodiment of the invention is shown in the drawings. They show 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  a longitudinal section through a total of three telescopic tubes in their locked position, in which the background lines have been left away for a better view, along line I/I from  FIG. 2   
           [0022]      FIG. 2  a view in the direction of the arrow II from  FIG. 1 , 
           [0023]      FIG. 3  a sectional view along line III/III from  FIG. 4  in the unlocked position of the toothed rack and the toothed strip, 
           [0024]      FIG. 4  a view in the direction of arrow IV from  FIG. 3 , 
           [0025]      FIG. 5  a view corresponding to  FIG. 1  of three telescopic tubes with all background lines in the locked position of the tubes, 
           [0026]      FIG. 6  a sectional view along line VI/VI from  FIG. 5  in the locked position, 
           [0027]      FIG. 7  the view from  FIG. 5  in the unlocked position of the toothed rack and toothed strip, 
           [0028]      FIG. 8  a sectional view along line VIII/VIII from  FIG. 7   
           [0029]      FIG. 9  a top view of the vacuum cleaner suction tube along line IX/IX from  FIG. 1   
           [0030]      FIG. 10  exploded view X from  FIG. 1 , 
           [0031]      FIG. 11  exploded view XI from  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    The telescopic tube joint  1  according to  FIGS. 1 to 4  consists of an outer tube  2 , a first inner tube  3  slidable therein and a second inner tube  4 , which telescopes into the first inner tube  3 . In reference to the second inner tube  4 , the first inner tube  3 , thus forms an outer tube. For this reason, it is stated in the generic terms of claim  1 , that the tube joint has at least one outer tube and at least one inner tube. However, to avoid confusion in the following description, the terms “outer tube  2 ”, “first inner tube  3 ” and “second inner tube  4 ” shall be maintained. 
         [0033]    The first inner tube  3  and the second inner tube  4  are provided with a plurality of teeth  5  in the form of an imprinted or, respectively, stamped toothed strip  6  on their peripheral surface. The toothed strip  6  is thus integrally joined with the respective inner tube. The gaps between the teeth  5  provide catch recesses which grip into a plurality of opposing teeth  7 , which are part of a short, toothed rack  8  which provides a catch element. This toothed rack  8  according to  FIGS. 1 and 3  can be slidably moved through an opening in the outer tube  2  in the direction of the double arrows  9  for locking and unlocking. The peripheral configuration of the toothed rack  8  and the opening  10  are similar in geometry and have clearance so that the toothed rack  8  can be slid into and out of the opening  10  without being canted (see  FIG. 9 ). As seen from  FIG. 9 , the peripheral configuration of the toothed rack  8  and the opening  10  are presently formed as a rectangle with slightly rounded corners. 
         [0034]    The toothed rack  8  is arranged on an extended end section  2   a  of the outer tube  2  and is encompassed by the rotary slide  11 . At the end  11   a  of the rotary slide  11 , finally, a front ring  12  is snapped on, which keeps the rotary slide  11  in its intended turned position. A sealing sleeve  13  is arranged between the inner periphery of the extended end section  2   a  of the outer tube  2  and the outer periphery of the first inner tube  3 . This sealing sleeve  13  can also be called a guiding sleeve, since on the one hand; it extensively seals the space between the outer periphery of the first inner tube  3  and the inner periphery of the outer tube  2 , which is important for the use of this telescopic tube joint as a vacuum cleaner suction tube. On the other hand, the sealing sleeve  13  acts, in reference to the telescopic ability of both tubes  2 ,  3 , as a guiding sleeve  13  in order to guide the respective inner tube  3  or  4  freely in the outer tube  2  or  3 , which is particularly important for the use of this telescopic tube joint  1  in tripods. 
         [0035]    Similarly, a further rotary slide  11  having a front ring  12  and a further sealing or, respectively guiding sleeve  13  is arranged in an expanded area  3   a  of the first inner tube  3 . 
         [0036]    As can be clearly seen in  FIGS. 1 and 10 , the gaps between the teeth  5  of the toothed strip  6  of the respective inner tube  3  or  4  engage into the opposing teeth  7  of the toothed rack  8  in the locked position shown there. 
         [0037]    The teeth  5  of the toothed strip  6  and the opposing teeth  7  in the toothed rack  8  are about the same size. Furthermore, the teeth  5 ,  7  are provided with straight toothing in the toothed strip  6  and the toothed rack  8 , i.e. the teeth  5  and the teeth  7  run in a straight line. Furthermore, the teeth are provided with even profiles  5   a,    7   a  that run along a horizontal  14  at an angle α between 30° and 90°, in the present case according to  FIGS. 10 and 11  at 60°. The tooth profiles  5   a,    7   a  are connected to one another at the crest  15  of the teeth  5 ,  7  via a radial rounding or an even flattening. 
         [0038]    As can be seen most clearly from  FIGS. 2 and 4 , the teeth  5 ,  7  over the width B on the toothed rack  8  or, respectively the toothed strip  6  are rounded convexly on their free ends and the bases  16  of the teeth  5  in the toothed strip  6  over their width B are rounded concavely. This is not a contradiction to the above features that the profiles  5   a  and  7   a  on the crests of the teeth  5 ,  7  are connected to one another via a radial rounding or, respectively flattening, since this connection runs axially as opposed to the rounding of the teeth  5 ,  7  in a manner as described in  FIGS. 2 and 4  running in a radial direction. 
         [0039]    As can be learned from  FIGS. 1 ,  3 ,  5  and  7 , the rotary slide  11  has a cylindrical outer periphery form, which is tapered or, respectively, rounded on both ends in a favorable form. 
         [0040]    As can be most clearly seen in  FIGS. 6 and 8 , the rotary slide  11  is provided with a recess  17  in an area of its inner peripheral surface, which corresponds to the width B and the length L of the toothed rack  8  extending into it in the unlocked positition. In an oval or elliptical formation of the toothed rack  8  and the opening  10 , the main axis and the auxiliary axis of the ellipses are approximately in the same plane and are approximately the same length considering a slight tolerance. 
         [0041]    As can be most clearly seen in  FIGS. 6 and 8 , a continuously narrowing inner peripheral area  18  runs along at least one side, presently along the left side of the recess  17  of the rotary slide  11 , which presses the toothed rack  8  with its teeth  7  into the bases  16  between the teeth  5  of the toothed strip  6  to achieve the locked position and by turning the rotary slide  11  in the direction of the arrow  19 . The locked position shown in  FIGS. 1 and 2  as well as in  FIGS. 5 and 6  is, thus, achieved. In this locked position, the outer tube  2  and the first inner tube  3  can no longer be slid relative to one another. The same goes for the first inner tube  3  acting as an outer tube in respect to the second inner tube  4 . Both of these tubes are shown in their locked positions in  FIGS. 1 ,  2 ,  5 , and  6 . 
         [0042]    In order to go from the unlocked position according to  FIG. 8  to the locked position according to  FIG. 6 , the rotary slide  6  only has to be turned clockwise to a minimal angle α in the direction of the arrow  19 . As soon as the continuously narrowing inner peripheral area  18  of the rotary slide  11  produces the locked position of the toothed rack  8  according to  FIG. 6 , the locked position is achieved. For unlocking, the rotary slide  11  is turned counter-clockwise or, respectively, in the opposite direction of the arrow  19  from the position in  FIG. 6  to the position in  FIG. 8 , to the left, in the drawings, until the toothed rack  8  can switch back into the recess  17 . 
         [0043]    In the unlocked position of  FIGS. 3 ,  4 ,  7  and  8 , the outer tube  8  can be slid in both directions of the double arrow  20  relative to the first inner tube  3 . The sliding force of the operator causes the tooth profiles  5   a  of the teeth  5  of the toothed strip  6  to push the tooth profiles  7   a  of the opposing teeth  7  in the toothed rack  8  upwards in a wedge shape having an angle β of, for example 60°. The opposing teeth  7  of the toothed rack  8  “hobble” over the teeth  5  of the toothed strip  6  until the desired telescope expansion or insertion length has been achieved. Then, one turn to an angle α of the rotary slide  11  according to  FIG. 8  in the direction of the arrow  9  is needed to achieve the locked position according to  FIG. 6 . Since the angle α is only very small, presently between 10° and 20°, the locking position is achieved within seconds with just one turn of the hand. 
         [0044]    As is clearly described in the exploded view of  FIGS. 10 and 11 , the profiles  5   a  in the toothed strip  6  as well as the profiles  7   a  of the opposing teeth  7  in the toothed rack  8  are formed straight, i.e. they run in a plane. This plane of the tooth profiles  5   a,    7   a  runs at an angle β along a horizontal  14  as is sketched in  FIGS. 10 and 11 . Both the teeth  5  in the toothed strip  6  and the opposing teeth  7  in the toothed rack  8  are provided with flat areas on their crests  15 , which engage in the corresponding flat areas in the tooth bases  16 . The form of the tooth crests  15  as well as the tooth bases  16  prevents damage to the to the teeth during the telescope process, when, for example, the opposing teeth  7  of the toothed rack  8  “hobble” over the teeth  5  of the toothed strip  6  during the sliding process. 
         [0045]    The tubes  2 ,  3  and  4  are advantageously produced of aluminum, wherein the rotary slide  11  with its front ring  12  as well as the sealing or, respectively, guiding sleeve  13  and the toothed rack all consist of polyamide. For the rotary slide  11  and for the front ring  12  as well as the sealing or, respectively, guiding sleeve  13 , POM and PE could be used. Here, the sealing or, respectively, guiding sleeve  13  simultaneously forms, in respect to the expanding area  2   a  of the outer tube  2 , a strengthening corset in this end area. The tubes  2 ,  3 ,  4  have different diameters: thus, for example, the second inner tube  4  can have an outer diameter of 32 mm, the first inner tube  3  an outer diameter of 35 mm and the outer tube  2  an outer diameter of 38 mm. The wall thickness of the tubes can measure 0.8 mm. Such a thickness is completely sufficient for imprinting a stable toothed strip  6  into the respective inner tube  3 ,  4 .