Patent Publication Number: US-9895040-B2

Title: Compact telescopic extension for an electric household appliance and associated electric household appliance

Description:
This application claims priority to IT Patent Application No. 102016000019841 filed Feb. 25, 2016, the entire content of which is hereby incorporated by reference. 
     BACKGROUND 
     The present invention relates to a telescopic extension, in particular for an electric household appliance, such as a vacuum cleaner, a vacuum cleaner drum, an electric broom, a carpet beater, a cyclonic vacuum cleaner, for a centralized suction system or a similar apparatus. The present invention also relates to an electric household appliance comprising such a telescopic extension. The telescopic extension according to the invention is compact when in the closed configuration. 
     STATE OF THE ART 
     Known telescopic extensions for electric household appliances comprise an inner tube and an outer tube sealingly slidable inside one another, a sleeve, a constraining device able to rigidly connect together (lock) the inner tube and the outer tube, a push-action slider engaging with the constraining device under the action of elastic means, and an actuating device operationally connected to the push-action slider. In these known telescopic extensions, the inner tube is provided with a row of notches of predefined shape, and the sleeve is fixed to the outer tube. The constraining device and the push-action slider are movably supported in said sleeve. The elastic means are also housed inside said sleeve. 
     The push-action slider acts on the constraining device under the action of the elastic means. It forces the constraining device to remain inside one of the notches of the inner tube so as to lock the tube inside the outer tube. 
     The actuating device, in turn, is configured to disengage the push-action slider from the constraining device so as to leave the constraining device free to be move radially outside of the notch of the inner tube. In this way the inner tube is released from the outer tube and may be slid relative to the outer tube so as to adjust the length of the extension. 
     EP 1 092 383 and WO 02/38026 A1 describe telescopic extensions for electric household appliances. 
     Depending on the suction direction in a telescopic extension an input end and an output end are identified. The input end is typically removably fixed to a suction tool such as a so-called vacuum cleaner brush or vacuum cleaner nozzle. The brush slides over the surface to be cleaned and sucks up solids or liquids such as dust, debris, crumbs or water. The material sucked up from the ground enters into the telescopic extension through the input end and exits the telescopic extension through the output end. Downstream of the telescopic extension the material sucked up from the ground is collected, passing optionally through another tube, for example a rigid or flexible tube of the spiral type. 
     Similarly, depending on the suction direction, an input end and an output end are also identified for the inner tube and outer tube. In fact, the input end of the inner tube corresponds to the input end of the telescopic extension and the output end of the outer tube coincides with the output end of the telescopic extension. 
     In the known telescopic extensions the sleeve, the constraining device and the corresponding actuating device are located substantially in the proximity of the input end of the outer tube. 
     The vacuum cleaner is used by gripping the telescopic extension close to its output end and directing the suction tool towards the surface to be vacuumed. In order to slide the inner tube relative to the outer tube, the use must hold the inner tube with one hand. With the other hand the user must push (or pull) the pushbutton and push (or pull) the outer tube relative to the inner tube. 
     SUMMARY OF THE INVENTION 
     The inventor has defined the object of optimizing the length of a telescopic extension of the aforementioned type. In particular, the inventor has defined the object of providing a telescopic extension having a length smaller than that of the known extensions in the closed configuration (when the inner tube is fully inserted in the outer tube), while maintaining substantially the same length in the fully extended configuration. Alternatively, the inventor proposes the object of providing a telescopic extension which has a length substantially the same as that of the known extensions in the closed configuration (when the inner tube is fully inserted in the outer tube), but which has a greater length in the fully extended configuration. 
     In any case, a significant advantage is obtained. In particular, with a telescopic extension having a smaller length in the closed configuration it is possible to obtain a package with smaller dimensions, with all the associated logistical and cost-related advantages. If it is not required to reduce the length in the closed configuration, as a result of the present invention the user has available a longer telescopic extension suitable for taller persons or for reaching zones situated further away. 
     The inventor has realized that, in order to achieve the aforementioned objects, it is necessary to reduce the length of the sleeve. 
     However, reducing the length of the sleeve has resulted in an instability of the various components and a consequent unacceptable lack of precision during operation of the telescopic extension. 
     According to a first aspect of the present invention, a telescopic extension is provided, said telescopic extension comprising:
         an inner tube;   an outer tube;
           wherein said inner tube and said outer tube are telescopically slidable relative to one another;   wherein said inner tube comprises, on an outer surface thereof, a plurality of deformations of predetermined shape;   
           a sleeve fitted inside said outer tube, at one of its ends;   a constraining device configured to lock sliding of the inner tube with respect to the outer tube, when said constraining device is at least partially engaged in one of said deformations;   a slider and elastic means, wherein said slider cooperates with said constraining device under the action of said elastic means; and   an actuating device operatively connected to said slider,   wherein said slider comprises a guiding device for providing a guided movement between said slider and said constraining device, wherein said slider comprises a substantially flat lower face and two side walls, wherein said guiding device comprises an inclined plane which is recessed with respect to the substantially flat lower face and is delimited by said side walls. Thanks to the above arrangement, the constraining device performs a guided movement which is laterally constrained by said side walls.       

     As said above, the inclined plane is delimited laterally by two side walls which provide stability in the direction perpendicular to the sliding plane. 
     Preferably, the side walls comprise surfaces which prolong the plane of the substantially flat face of the slider. 
     The substantially flat face of the slider is preferably configured to translate on a bottom surface of a longitudinal cavity in the sleeve. 
     Preferably the width of the inclined plane corresponds substantially to the width of the slider. 
     The slider may also comprise a guiding edge for the inclined plane. 
     The slider may comprise a hole for retaining at least a portion of said elastic means. Preferably the inclined plane starts from a position substantially corresponding to the bottom of the hole. 
     The sleeve preferably comprises a circular stiffening collar and a longitudinal rib configured to engage a corresponding opening at an input end of the outer tube. 
     According to another aspect, the present invention provides an electric household appliance comprising a telescopic extension as defined above and in the continuation of the present description, as well as in the drawings. 
     In the present description and the claims the expression “tube having a cross-section with a substantially constant diameter” is used to indicate that the tube does not have a deformed portion able to house the sleeve entirely or partly. However, there may be deformations in the tube which have a different function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become clear from the following detailed description of examples of embodiments, to be read with reference to the accompanying drawings, in which: 
         FIG. 1 a    is an axonometric view of a telescopic extension according to an embodiment of the invention in its partially extended configuration; 
         FIG. 1 b    shows the telescopic extension according to  FIG. 1 a    in its closed configuration; 
         FIG. 2  shows an exploded view of the sleeve, the constraining device and other components; 
         FIG. 3 a    shows a portion of the telescopic extension with the inner tube and the outer tube slidable relative to each other; 
         FIG. 3 b    shows a portion of the telescopic extension with the inner tube and the outer tube locked relative to each other; and 
         FIGS. 4 a , 4 b , 4 c , 4 d  and 4 e    show various views of the slider of the telescopic extension according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EXAMPLES 
       FIGS. 1-3  show a telescopic extension  10  for an electric household appliance, such as a vacuum cleaner, according to an embodiment of the present invention. The extension  10  comprises an inner tube  12 , an outer tube  14 , a sleeve  16 , a constraining member  18 , a push-action slider  20 , an elastic member  22  and an actuating device  24 . 
     The inner and outer tubes  12  and  14  are sealingly slidable one inside the other one. Preferably a sealing gasket may be inserted between the inner tube  12  and the outer tube  14 . The tubes  12  and  14  are, for example, made of chrome-plated stainless steel or painted externally. Alternatively they may be made of any metal. 
     The inner tube  12  has a first end (or input end)  12 ′ and a second end (or output end) which is not visible in the figures. The outer tube  14  has a first end (or input end)  14 ′ and a second end (or output end)  14 ″. The telescopic extension  10  therefore has as input end the input end  12 ′ of the inner tube  12  and as output end the output end  14 ″ of the outer tube  14 . 
     The inner tube  12  preferably has a longitudinal groove  121  which is substantially parallelepiped-shaped and has a bottom wall  122  in which a row of notches  123  is formed. Preferably, the notches  123  have a partially cylindrical shape and are configured to house a portion of the constraining member  18 , as will be described below. 
       FIG. 2  is an exploded axonometric view of the sleeve  16 , the constraining member  18 , the slider  20 , and the elastic member  22  of the actuating device  24 . 
     The sleeve  16  is designed to be inserted inside the input end  12 ′ of the outer tube  14 . Preferably the sleeve  16  comprises a substantially cylindrical body with a circular stiffening collar  161  at its input end. The sleeve  16  also comprises, preferably, a longitudinal rib  162  configured to engage a corresponding opening at the input end  14 ′ of the outer tube  14 . This prevents the sleeve  16  from rotating with respect to the outer tube  14 . Moreover the rib  162  increases locally the thickness of the sleeve  16 . 
     Preferably the sleeve  16  comprises a longitudinal cavity  163 . Preferably the longitudinal cavity  163  comprises, in succession, a first section  164  provided with bottom  164 ′, a second open section  165 , a third narrower open section  166  and a fourth section  167  with closed bottom  167 ′. 
     Preferably, the constraining member  18  comprises a T-shaped metal plate. The head  181  of the T is adapted to be inserted inside the fourth section  167  of the longitudinal cavity  163 . The shank  182  of the T is adapted to be retained inside the third section  166  of the longitudinal cavity  163 . The end  183  of the T is curled and forms a small cylinder  183 . When the head  181  of the T is inserted inside the fourth section  167 , the constraining member is free to rotate, as may be understood from a comparison of  FIGS. 3 a  and 3 b   . The movement of the constraining member  18  will be described further in the continuation of the present description. 
     The slider  20  comprises a base  201  and a projecting part  202  configured to engage the actuating member  24  which may be for example a shaped button for pushing the slider in one direction or in the opposite direction. 
     The slider  20  also comprises a hole  203  in its rear part for receiving one end of the elastic member  22 . 
     The actuating member  24  comprises a housing cooperating with the projecting part  202  so as to connect the actuating member substantially rigidly together with the slider  20 . 
     Preferably the sleeve  16  also comprises one or more windows  168  for cooperating with one or more corresponding sawteeth  141  present in the wall of the outer tube  14  and for locking the sleeve to the outer tube, preventing it from becoming detached. Preferably there are two windows  168 , which are situated diametrically opposite each other, and two sawteeth  141 . 
     With reference to  FIG. 4 , the slider  20  will now be described in greater detail. 
     The base  201  has substantially a parallelepiped shape. Preferably, the rear end has chamfered corners  204  and the aforementioned blind hole  203  for receiving one end of the elastic member  22 . Preferably the elastic member  22  is in the form of a helical spring. 
     The lower face of the base forms a substantially flat surface  205 . However, one part thereof is provided with a ramp having an inclined plane  206 . In particular it is provided with an inclined plane which is open towards the front end (opposite to that where the hole  203  for the spring is present). Preferably, the entrance area of the inclined plane has a different inclination and forms a guiding surface  207 . Preferably the inclined plane is inclined with respect to the lower face of the base at an angle of between about 5 degrees and about 10 degrees. Preferably it is equal to about 7-8 degrees. Preferably the inclined plane  206  starts from a position substantially corresponding to the bottom of the hole  203  as shown in the cross-section of  FIG. 4   b.    
     Preferably there are two guiding side walls  208  along the sides of the inclined plane. The side walls  208  delimit laterally the inclined plane and prolong (with surfaces  208 ′) the substantially flat surface of the lower face. Therefore the lower face has a U shape formed with the surface  205  and the two surfaces  208 ′. 
     The width of the inclined plane  206  substantially corresponds to the width of the shank  182  of the constraining member  18 . Owing to the side walls, the shank  182  remains guided during its translatory movement. 
     Hereinbelow operation of the telescopic extension  10  according to the present invention will be described with reference in particular to  FIGS. 3 a    and  3   b.    
     In the configuration shown in  FIG. 3 a    the spring  22  is compressed as a result of the user pressing the actuating device  24  towards the input end of the telescopic extension. In this position, the constraining member  18  is not acted on by the slider  20  and in particular does not engage the inclined plane. Therefore, in this position, the curled end  183  of the constraining member  18  does not engage any of the notches  123 . During a further sliding movement of the outer tube with respect to the inner tube, when the curled end  183  of the constraining member  18  is located opposite one of the notches  123 , it passes beyond it. In other words, when the constraining member is not locked, the end  183  and the notches  123  do not form obstacles. 
     As can be understood, the head  181  of the constraining member  18  remains within the cavity  167 . The constraining member  18  therefore performs a rotational movement about an axis substantially coinciding with the axis of the head  181 . 
       FIG. 3 b    shows the configuration where the outer tube  14  and the inner tube  12  are locked to each other and cannot slide relative to each other. In this position the actuating member  24  is no longer operated by the user and the spring  22  pushes the slider  20  towards the output end of the telescopic extension  10 . In this position, the constraining member  18  is acted on by the slider  20  so that the curled end  183  is partly housed inside one of the notches  123 . In this position the upper face of the constraining member  18  makes contact with the inclined plane  206  of the slider  20 . As a result of the spring  22 , the position shown in  FIG. 3 b    is a stable position. The shank  182  of the constraining member  18  is retained laterally during its movement so as to make contact with the inclined plane  206 . The retaining action is obtained by means of the side walls  208  situated along the sides of the inclined plane. 
     The sliding movement of the slider  20  is also stable and guided by the side walls of the first section  164  of the longitudinal cavity  163  and by the bottom  164 ′. It should be emphasized that the surface  205  and the surfaces  208 ′ of the side walls slide on the bottom  164 ′ of the section  164 . This ensures a stable and precise movement and at the same time reduces the friction between the bottom  164 ′ of the section  164  and the bottom face of the slider  20 . 
     The sleeve according to the present invention has a smaller length than that of the known sleeves. This allows the mechanism for locking together the outer tube and the inner tube to be situated closer to the input end of the outer tube. This makes it possible to have a first locking notch situated close to the end of the outer tube. The outer tube may therefore be about 20-30 mm shorter than the known tubes if the object is to have a telescopic tube which is shorter in the closed configuration (while maintaining the same length when extended). Alternatively, as a result of the present invention, for the same dimensions in the closed configuration, the telescopic extension according to the invention is longer than the known telescopic extensions in the completely extended configuration. The maximum length is increased by about 20-30 mm. This length corresponds to a percentage which varies from 3% to 10% depending on the models. This percentage increases on models which have a smaller extended length. For example, it is about 10% in the case of relatively short telescopic extensions (200-300 mm).