Telescopic extension for a vacuum cleaner

Abstract: The invention relates a telescopic extension for a vacuum cleaner comprising an internal tube (2), an external tube (3), and a sleeve (1), wherein the internal tube is provided with a row of notches (4) suitable for receiving a constraining element (250). The sleeve (1) comprises at least one first tubular casing (100) and one second tubular casing (110) fitted over said first tubular casing (100); said first tubular casing (100) is provided with snap-on connecting means (120, 130) by means it is connected to the external wall (9) of said external tube (3); said constraining element (250) is movably supported by said first tubular casing (100) and a manual operating means (290) of said constraining element (250) is slidingly supported by said first and second tubular casing (100, 110).

Description: The present invention relates to a telescopic extension for an intake conduit of a vacuum cleaner, comprising an internal tube and an external tube sliding one inside the other, so that the length of the same extension can be adjusted telescopically and that the same tubes can be clamped in a relative selected positions to form a handle of desired length. Generally in vacuum cleaners a suction mouth or a cleaning brush are connected to a vacuum cleaner by means of a conduit comprising a rigid section that facilitates its grasp, and a flexible section. The rigid conduit section is formed by a telescopic extension comprising an internal tube and an external tube, sealingly sliding one inside the other, so as to convey air and dust in the flexible section and to constitute a handle that can be adjusted in length, suitable for maneuvering the suction mouth or the cleaning brush; thus the extension should be capable of transmitting longitudinal forces of some magnitude. The US patent No. 3.351.363 describes a telescopic extension for vacuum cleaners, comprising an internal tube and an external tube, sealingly sliding one inside the other, wherein a sleeve in plastic material is mounted overhanging on the external wall of the external tube and is fastened to it by deformation of the same external tube inside an annular groove on it, or it is mounted inside a flared section of said external tube and is fastened by upseting an edge of said external tube to act as a guide of the internal tube; the internal tube is provided with a row of hemispherical notches, appropriately spaced, suitable for receiving a constraining element formed by a ball that can be movably supported radially by the same sleeve. In the sleeve there is also mounted a sliding or rotating manually-operated ring nut which, normally, under the action of a spring, thrusts said ball radially, through a element of thrust, into one of the notches of the internal tube, so as to lock the latter in the desired position with respect to the external tube; by moving said ring nut, against the action of the spring, the ball is disengaged and leaves the internal tube free to slide with respect to the external tube and allows the length of the extension itself to be adjusted. One of the main disadvantages of this telescopic extension is represented by the fact that the connection between sleeve and external tube is accomplished by the latter's deformation through expansion instruments and through an upseting instrument; this operation, in addition to making the manufacturing cycle more complex and more expensive, can jeopardize the integrity of the tube, thus increasing the number of rejects. Another disadvantage of the embodiement of the extension described having said sleeve overhanging, is represented by the fact that the sleeve constitutes a component that is too weak to effectively support the repeated stresses to which it is subjected during the operations for which the extension is destined. Furthermore, in said latter telescopic extension impressions appear in the element of thrust in plastic material due to the fact that the contact with the element of constraining made of steel takes place in a very narrow area substantially limited to a point. Therefore in time clearence appears between the element of thrust and the element of constraining which remains loose in the notches of the internal tube, and is no longer capable of firmly locking the latter with respect to the external tube, in the desired position. An object of the present invention is to provide a telescopic extension for vacuum cleaners that should be made and assembled in a manner that is easy and safe, without involving deformations of the external tube. Another object of the present invention is to provide a telescopic extension that is strong, functional, reliable, and exempt from loose clearances even after prolonged use. According to the invention, it is provided a telescopic extension for a vacuum cleaner comprising an internal tube, an external tube, sealingly sliding one inside the other, a sleeve mounted on an external wall of said external tube, the internal tube being provided with a row of notches of a predetermined shape, appropriately spaced, a constraining element, and a manual operating means subjected to the action of elastic means, capable of keeping an element of thrust in engagement with said constraining element, to force it into one of the notches of said internal tube and to lock the latter with respect to the external tube, and capable, against the action of said elastic means, of disengaging said thrust means from said constraining element, leaving said internal tube free to slide inside the external tube, characterized in that said sleeve comprises at least one first tubular casing and one second tubular casing fitted over said first tubular casing, said first tubular casing being provided with snap-on connecting means with which it is connected to said external wall of the external tube, said constraining element being movably supported by said first tubular casing, said operating means being slidingly supported by said first and second tubular casing. According to a preferred embodiment said snap-on connecting means are constituted by at least one partially-elastic tang, obtained in said first tubular casing and provided with at least one protrusion capable of engaging a corresponding opening of said external tube. Preferably said first tubular casing is provided with a further tang, partially elastic, provided with a longitudinal projection suitable for engaging a corresponding longitudinal slot of said external tube and a corresponding longitudinal groove of said internal tube, so that relative sliding motions are allowed and relative rotations are prevented between said tubes. Advantageously, said first tubular casing is provided with a projection suitable for engaging a centering port of said external tube; it is also provided with a seat capable of supporting said constraining element and is provided with guide recesses suitable for slidingly supporting a pushbutton constituting said operating means, said pushbutton being slidingly supported in a guide port of said second tubular casing. With this invention a strong, functional, reliable telescopic extension is accomplished, having a sleeve firmly connected to the external tube by means of easily assembled connecting means. The features and advantages of the invention shall now be described with reference to the drawings which, as non-limiting examples, represent preferred embodiments of this invention, and of which: Fig. 1 shows a longitudinal cross-section of an embodiement of a telescopic extension for vacuum cleaners according to the invention; Fig. 2 is a cross-sectional view according to the plane indicated with II-II in Fig. 1; Fig. 3 is a plan view from above of a first tubular casing, of a pushbutton and of a constraining element of the telescopic extension of Fig. 1; Fig. 4 is a partially sectioned enlarged view according to the plane indicated with IV-IV in Fig. 1. In Fig.s 1 and 2 there is indicated as a whole with 1 a sleeve for a telescopic extension for vacuum cleaners constituted by an internal tube 2 and by an external tube 3 in steel sheet chromium-plated externally, slidable one inside the other, with the interposition of a usual sealing ring, not shown; the tube 2 is provided with a series of semicylindrical notches 4 located at a predetermined distance one from the other and with a longitudinal groove 5; the external tube 3 is provided with two diametrically opposite openings 6, with a Longitudinal slot 7 and with a port 8 that are also diametrically opposite to one another. The sleeve 1 is formed by a first tubular casing 100 of suitable plastic material, and by a second tubular casing 110 in steel sheet chromium-plated externally, fitted with a slight interference over said first tubular casing 100. The tubular casing 100 is fitted over the external wall 9 of the external tube 3 and is provided with snap-on connecting means constituted by two tangs 120, partially elastic, each provided with a protrusion 130 suitable for engaging a corresponding opening 6 of the external tube 3; the tubular casing 100 is also provided with a tang 140, partially elastic, provided with a longitudinal projection 150 suitable for engaging the slot 7 of the external tube 3 and the longitudinal groove 5 of the internal tube 2, so that the latter can slide, but not rotate, with respect to the external tube 3. There is indicated with 160 a projection of the tubular casing 100 suitable for engaging a centering port 8 of said external tube 3; as is also shown in Fig. 3, in the projection 160 there are obtained a recess 170 with a rectangular area connected to a recess 180 also with a rectangular area, an opening 190, a ramp 200 and a semi cylindrical recess 210; the tubular casing 100 is finally provided with an annular edge 221 which acts as an abutment to the external tube 3 and to the second tubular casing 110 and that is fitted over the internal tube 2. The second tubular casing 110 is provided with a port 232 and with a relief 240 located opposite the projection 160 of the first tubular casing 100. There is indicated as a whole with 250 a constraining element, also visible in Fig. 3, comprising a small partially cylindrical bar 260, in steel, preferably in hardened stainless steel, suitable for being inserted in the notches 4 of the internal tube 2; the constraining element 250 can be constituted by a ball or by a roller, but preferably it is made by a small cylindrical bar 260 which is integral with an appendix formed by a small plate indicatd as a whole with 270, which in turn is integral with a pin 280; the small plate 270 is constituted by two portions 272 and 271, inclined at an angle to one another of slightly less than 180°; the pin 280 and the portion 271 of the small plate 270 rest up against the recess 210 and the ramp 200, so that the portion 272 of said small plate is inclined at a given angle, in the specific case 5°, with respect to the longitudinal axis of the tubes 2 and 3. There is indicated as a whole with 290 a pushbutton in suitable plastic material, also visible in Fig. 3, slidingly mounted in the rectangular recesses 170 and 180 of the tubular casing 100 and engaged by means of tongues 300 with the guide port 232 of the tubular casing 110; the pushbutton 290 is provided with a blind hole 310 in which there is housed a pre-loaded helical spring 320, reacting against the wall 340 of the tubular casing 100; the pushbutton 280 is provided with an element of thrust, indicated as a whole with 350, provided with a thrust wall 330 inclined at an angle with respect to the longitudinal axis of the tubes 2 and 3 that is the same as the one selected for the portion 272 of the small plate 270, in the specific case 5°. The pushbutton 290, under the action of the spring 320, keeps the thrust wall 330 in contact with the entire surface of the portion 272 of the small plate 270, forcing the small bar 260 inside the slot 4 of the tube 2, that is under the opening 190 of the tubular casing 100. To adjust the length of the extension, the sleeve 1 is grasped and the pushbutton 290 is pulled from left to right, in the position represented in Fig. 1, so that the thrust wall 330 moves away from the portion 272 of the small plate 270 and releases the small bar 260 to exit from the notch 4; this allows the tube 2 to slide inside the tube 3 until the desired length is reached. When the pushbutton 290 is released, under the action of the spring 320, the thrust wall 330 returns in contact with the portion 272 of the small plate 270 and again pushes the small bar 260 inside the notch 4 of the tube 2 that has been brought opposite the opening 190, so that the tubes 2 and 3 are safely locked one with respect to the other. For mounting the sleeve 1 proceed by mounting the tubular casing 10O on the wall 9 of the external tube 3 and by firmly fastening it to said wall 9 by means of the protrusions 130 of the tangs 120 and the projection 150 of the tang 140, and by means of the tubular casing 110, that is fitted with a slight interference over said first tubular casing 100; a handle is thus formed with a very strong grip, suitable for maneuvering the suction conduit of vacuum cleaners. The advantages of the described sleeve 1 are represented by its strength, efficiency, reliability, and by the simplicity of assembly, due to the presence of the two tubular casings 100 and 110 and of the tangs 120, 140 with respective protrusions 130 and projection 150.

Claims: A telescopic extension for a vacuum cleaner comprising an internal tube (2), an external tube (3), sealingly sliding one inside the other, a sleeve (1) mounted on an external wall (9) of said external tube (3), the internal tube (2) being provided with a row of notches (4) of a predetermined shape, appropriately spaced, a constraining element (250), and a manual operating means (290) subjected to the action of elastic means (320), capable of keeping an element of thrust (350) in engagement with said constraining element (250) to force it into one of the notches (4) of said internal tube (2) and to lock the latter with respect to the external tube (3), and capable, against the action of said elastic means (320), of disengaging said thrust means (350) from said constraining element (250), leaving said internal tube (2) free to slide inside the external tube (3), characterized in that said sleeve (1) comprises at least one first tubular casing (100) and one second tubular casing (110) fitted over said first tubular casing (100), said first tubular casing (100) being provided with snap-on connecting means (120, 130) with which it is connected to said external wall (9) of the external tube (3), said constraining element (250) being movably supported by said first tubular casing (100), said operating means (290) being slidingly supported by said first and second tubular casing (100, 110). Telescopic extension according to claim 1, characterised in that said snap-on connecting means (120, 130) are constituted by at Least one partially-elastic tang (120), obtained in said first tubular casing (100) and provided with at least one protrusion (130) suitable for engaging a corresponding opening (6) of said external tube (3). Telescopic extension according to claim 1, characterised in that said first tubular casing (100) is provided with a further tang (140), partially elastic, provided with a longitudinal projection (150) suitable for engaging a corresponding longitudinal slot (7) of said external tube (3) and a corresponding longitudinal groove (5) of said internal tube (2), so that relative sliding motions are allowed and relative rotations are prevented between said tubes (2, 3). Telescopic extension according to claim 1, characterised in that said second tubular casing (110) is fitted with a slight interference over said first tubular casing (100). Telescopic extension according to claim 1, characterised in that said first tubular casing (100) is provided with a projection (160) suitable for engaging a centering port (8) of said external tube (3). Telescopic extension according to claim 1, characterised in that said first tubular casing (100) is provided with a seat (190, 200, 210) suitable for supporting said constraining element (250) and is provided with guide recesses (170, 180) suitable for slidingly supporting a pushbutton (290) constituting said operating means, said pushbutton (290) being slidingly supported in a guide port (232) of said second tubular casing (110). Telescopic extension according to claim 6, characterised in that said constraining element (250) comprises a small partially cylindrical bar (260) integral with a small plate (270) in turn integral with a pin (280), at least one portion (272) of said small plate (270) being supported in a ramp (200) of said seat (190, 200, 210) of said first tubular casing (100) inclined at a given angle with respect to the longitudinal axis of said tubes (2, 3), said pin (280) being supported in a semicylindrical recess (210) of said first tubular casing (100), said element of thrust (350) being provided with a thrust wall (330) inclined at the same angle with respect to said axis of the tubes (2, 3), capable of coming into contact, under the action of said elastic means (320), with the entire surface of said portion (272) of the same small plate (270).

Inventors: CANALE GIUSEPPE, CANALE, GIUSEPPE
Applicants: OMEC SPA, OMEC S.P.A.
Application year: 1992
Main classification: A47L9
IPC codes: A47L9, F16L27