TELESCOPIC EXTENSION FOR A HOUSEHOLD APPLIANCE AND METHOD FOR ASSEMBLING THEREOF

Abstract: A telescopic extension (1; 41) for a household appliance comprises an inner tube (2) tightly sliding in an outer tube (3), a sleeve (4; 44), a constraining element (5) between the inner tube (2) and the outer tube (3), a thrust element (6) and an actuator (7). In the extension (1; 41), a tubular end portion (9; 49) associated with the outer tube (3) has a relief (11) forming a niche (12) and the sleeve (4; 44) is provided with a projection (15) which is inserted in the niche (12) and has a hollow (18) wherein the constraining element (5), thrust element (6) and a spring (21) are completely housed. The thrust element (6) is formed by a lengthened, flattened slider (28) provided with a narrow portion (20) having recesses and the actuator (7) has protruding wings (37) provided with inner small teeth (38) which are snap-on coupled with the recesses.

Description: "Telescopic extension for a household appliance and method for assembling thereof" * * * * * * This invention relates to a telescopic extension for a household appliance and a method for assembling thereof. EP-B1 -0 520 534 describes a telescopic extension for a vacuum cleaner, comprising an inner tube and an outer tube, sliding tightly one within the other, a sleeve, a constraining means between the inner and outer tube, a thrust slider and an actuating pushbutton. The inner tube is provided with a row of notches of a preselected shape and the outer tube has a tubular end portion of a flared shape, which is integral with the outer tube and carries a sleeve fastened to its interior. The constraining means consists of a small cylinder integral with a small plate provided with a pin. By means of the pin and the small plate, the small cylinder is rotatably supported in a hollow of the sleeve. The sleeve has an opening through which the small cylinder can engage a notchof the inner tube and disengage from the same. In this telescopic extension, the thrust slider is integral and is formed as a single piece with the actuating pushbutton. The thrust slider is slidingly supported inside the hollow of the sleeve and is subjected to the action of spring means. The spring means operate the thrust slider to engage the small plate integral with the small cylinder and pin, so as to force the latter into the notch of the inner tube and to lock the inner tube in the outer tube. The extension thus assumes a preselected length. For adjusting the extension's length, the actuating pushbutton is manually pushed against the action of the spring means, so as to allow the thrust slider to disengage from the small plate and to let the small cylinder exit from the notch of the inner tube, thus unlocking the inner tube from the outer tube. By sliding the inner tube in the outer tube, the extension assumes the desired length. For assembling the extension, the sleeve is fitted over the internal tube and the pusbutton-slider assembly is pre-mounted in the hollow of the sleeve, together with the spring means and the constraining means. The sleeve is then inserted in the tubular end portion, centered with respect to it, and the inner tube is mounted inside said outer tube. For allowing the pushbutton protruding from the slider to pass through, the tubular end portion of the outer tube must have an opening extending up to the outer rim and forms an inlet mouth for the slider-pushbutton assembly. An opening of this shape and width has the disadvantage of weakening the outer tube and thus reducing its resistance to the working stresses. Moreover, the need to hold the slider, the spring means and the constraining means firmly inside the hollow of the sleeve, before and while inserting the sleeve in the tubular end portion, make the assembling difficult and expensive. EP-B1 -0 601 620 describes a telescopic extension for a vacuum cleaner which comprises, as for the extension of EP-B1 -0 520 534, an inner and an outer tube sliding tightly within each other, a sleeve, a constraining means between the outer and inner tube, a thrust slider and an actuating pushbutton. In this second extension, the thrust slider is always integral and is formed as a single piece with the actuating pushbutton, while the sleeve is fastened to the outer tube. A tubular end portion, which is separate from the outer tube and has an internal diameter wider than the outer diameter of the outer tube, is fitted over said sleeve. The constraining means and the thrust slider are movably supported in a hollow of the sleeve. The separate tubular portion has an opening extending up to the external rim and forms an inlet mouth for the slider-pusbutton assembly so as to allow the pushbutton protruding from the thrust slider to pass through. The outer tube also has an opening of the same shape, which allows the constraining means to engage a notch of the inner tube, and has a width capable of housing a projection of the sleeve, which allows it to be centered with respect to the outer tube. This second extension is rather stronger than the first one, but its assembling is still quite difficult and expensive for the reasons already mentioned. A first object of this invention is a telescopic extension for a household appliance, preferably a vacuum cleaner, stronger and more efficient than those described in the foregoing documents. A second and even more important object of the invention is to allow the structure of this telescopic extension to be manufactured and assembled in a simpler and more economical manner than that required by said known extensions. According to a first aspect, this invention relates to a telescopic extension for a household appliance comprising an inner tube and an outer tube sliding tightly within each other, a sleeve, a constraining means capable of fastening said inner and outer tube, a thrust element in engagement with said constraining means under the action of spring means, and actuating means operatively connected to said thrust element, said inner tube being provided with a row of notches of preselected shape, a tubular end portion provided with a slot being associated with said outer tube, said sleeve being fastened to said tubular end portion, said constraining means, thrust element and spring means being movably supported in said sleeve, said thrust element acting on said constraining means, under the action of said spring means, to force said constraining means into one notch to lock said inner tube in said outer tube, said actuating means being capable of disengaging said thrust element from said constraining means to let said constraining means exit from said notch and unlock said inner tube from said outer tube, allowing the inner tube to slide in respect of said outer tube for adjusting the length of said extension, said actuating means being a piece separate from said thrust element and having protruding wings capable of penetrating said slot, characterised in that said tubular end portion has a relief forming a niche and said sleeve is provided with a projection which is inserted in said niche and has a hollow wherein said constraining means, thrust element and spring means are completely housed, said thrust element, in turn, is formed by a lengthened, flattened slider provided with a narrow portion having recesses and said protruding wings of said actuating means are provided with inner small teeth capable of being snap-on coupled with said recesses. According to a second aspect, this invention relates to a method for assembling a telescopic extension for a household appliance, comprising an inner tube, an outer tube, a sleeve, a constraining means capable of fastening said inner tube and outer tube, a thrust element, actuating means and spring means, said inner tube being provided with a row of notches having a preselected shape, a tubular end portion provided with a slot being associated with said outer tube, said actuating means being a piece separate from said thrust element and having protruding wings capable of penetrating said slot, where said method comprises the following steps: a) fitting said sleeve over one of said inner tube and outer tubes, b) movably placing said constraining means, thrust element and spring means in said sleeve, c) inserting said inner tube in said outer tube so as to tightly slide one within the other and inserting said sleeve in said tubular end portion, and d) inserting said wings of said actuating means in said slot of said tubular end portion, characterised in that e) in step b), said constraining means, thrust element and spring means are completely housed into a hollow of a projection of said sleeve, f) in step c), said sleeve is centered in respect of said outer tube by means of said projection which fits a niche of a relief of said tubular end portion, and g) in step d), inner small teeth of said wings are snap on coupled to recesses of a lengthened, flattened slider which forms said thrust element so that said actuating means are fastened to said thrust element. The telescopic extension of this invention has the advantage of being very compact and capable of withstanding the working stresses. The method of assembling according to this invention considerably simplifies the assembling steps and eliminates mounting difficulties and errors, because the thrust element and the spring means are completely housed in the hollow of the sleeve and remain properly positioned therein when the sleeve is inserted inside the tubular end portion. Thereafter, the actuating means are fastened to the thrust element by causing their coupling elements to penetrate the slot in the tubular end portion. Thus, the method of this invention substantially reduces the assembling time and costs, and, moreover, it can be easily automatized. Features and advantages of the invention shall now be described with reference to embodiments shown as a non limiting example in the enclosed drawings, where: Fig. 1 is a longitudinal cross-sectional view of a telescopic extension for a household appliance, embodied according to the invention; Fig. 2 shows the extension of Fig. 1 in a different operating condition; Fig. 3 is a cross-sectional view according to the plane indicated with III - III in Fig. 1 ; Fig. 4 is a cross-sectional view according to the plane indicated with IV - IV in Fig. 2; Fig. 5 shows disassembled the extension of Fig. 1 ; Figures 6 and 7 are enlarged bottom and side views, respectively, of a thrust slider of the telescopic extension of Fig. 1 ; Fig. 8 is a longitudinal cross-sectional view of a variant of the telescopic extension of Fig. 1 ; Fig. 9 is a cross-sectional view according to the plane indicated with IX - IX in Fig. 8. Figures 1 and 2 show a telescopic extension for a household appliance, such as a vacuum cleaner, indicated as a whole with 1. The extension 1 comprises an inner tube 2 and outer tube 3, sliding tightly one within the other, a sleeve 4, a constraining means 5, a thrust element 6 and actuating means 7. The inner tube 2 has a row of notches 8 of a partially cylindrical shape. The inner tube 2 is provided with an usual sealing gasket (not shown) which allows said inner tube 2 to slide tightly within the outer tube 3. The outer tube 3 has a tubular end portion 9 integral thereto that is formed as a single piece having the same inner and outer diameter as said outer tube 3. The tubular end portion 9 is provided with a relief 11 of a substantially parallelepiped shape, projecting toward the outside, which encloses a niche 12. The upper wall 10 of the relief 1 1 has a slot 13 provided with protruding fins 14 (Fig. 4). The sleeve 4 has a projection 15 having a substantially parallelepiped shape that fits the niche 12 for centering purpose. The projection 15 has a hollow 18 in which the constraining means 5, thrust slider 6 and a spring 21 are housed. For example, the tubes 2 and 3 are made of chromium-plated stainless steel sheet and the sleeve 4 is made of a suitable plastic material. The constraining means 5 is formed by a small cylinder 22 integral with a small plate 23 provided with a pin 24, made for example of steel. The hollow 18 is provided with a semi-cylindrical cavity 25 housing the pin 24 and an inclined ramp 26 on which the small plate 23 rests. The hollow 18 is provided with an opening 27 which allows the small cylinder 22 to move in a substantially radial direction to engage a notch 8 of the inner tube 2 and to disengage said cylinder 22 from said notch 8. The thrust element 6 is formed by a slider 28 with an inclined wall 29 capable of remaining in contact with the small plate 23 (Figs. 6 and 7). The wall 29 and the ramp 26 have substantially the same inclination angle (about 5°) with respect to the longitudinal axis 30 of the tubes 2 and 3. The slider 28 has a narrow portion 20 provided with recesses whose function will be explained hereinafter. The slider 28 is provided with a blind hole 31 partially housing a spring 21. The spring 21 reacts on a wall 32 of the hollow 18 and is mounted precharged so that the inclined wall 29 of the slider 28 is normally kept in contact with the small plate 23 (Fig. 1 ) in this manner, the small cylinder 22 goes out of the opening 27 and is forced inside a notch 8 of the inner tube 2 (Figs. 1 and 3). The tubes 2 and 3 are thus firmly connected and form an extension 1 of the desired length. The sleeve 4 is inserted in the tubular end portion 9 so that it is centerd by the projection 15 penetrating the niche 12 and is positioned in longitudinal direction by a bent rim 16 which abuts against an outer rim 19 of the tubular end portion 9. The sleeve 4 is fastened to the tubular end portion 9 by means of fins 14 which are bent back against walls 33 of the hollow 18 (Fig. 4) and by means of indentations in the tubular end portion (not shown). The sleeve 4 is provided with a protrusion 34 which enters a longitudinal groove 35 of the inner tube 2 and guides the inner tube 2 with respect to the outer tube 3 when one slides inside the other for adjusting the length of the extension. The actuating means 7 are formed by of a pushbutton 36 having partially elastic wings 37, protruding downward and provided with inner small teeth 38. The wings 37 penetrate through the slot 13 and are fastened to the slider 28 by means of the inner teeth 38, which are snap-on fastened to the recesses of the narrow portion 20 (Fig. 4). As shown in Fig. 5, the slider 28 is a piece separate from the pushbutton 36 and has a lengthened and flattened shape which allows it to completely enter the hollow 18 of the sleeve 4, together with the spring 21 , thus making easy the introduction of the sleeve 4 inside the tubular end portion 9. After mounting, the slider 28 and the spring 21 lie completely inside the wall 10 which acts as a housing for the thrust slider 28. (Figs. 1 and 2). A further advantage of the slider 28 is that the contact between its inclined wall 29 and the small plate 23 is extended over a surface. In fact, the possible wear of the wall 29 will be uniformly distributed over its entire surface, and the presence of the spring 21 avoids the occurrence of clearance between the slider and the small plate. When adjusting the length of the extension 1 , the pushbutton 36 is actuated by hand, by moving it from the position of Fig. 1 to that of Fig. 2, so that the wall 29 moves away from the small plate 23 and let the small cylinder rise and exit from the notch 8 of the tube 2 in which it was engaged. This allows the tube 2 to slide within the tube 3, until reaching the desired length of the extension 1. The assembling of the telescopic extension 1 comprises mounting the sleeve 4 over the inner tube 2, wherein it is guided by means of the protrusion 34 and the longitudinal groove 35, and then placing the small cylinder 22 into the sleeve 4. The small plate 23 rests on the ramp 26 and the pin 24 is housed into the cavity 25 so that the small cylinder 22 is positioned opposite the opening 27. The slider 28 and the spring 21 are then mounted in the hollow 18 of the sleeve 4. The slider 28 and the spring 21 remain completely housed in the hollow 18 and the sleeve 4 can therefore be easily inserted into the tubular end portion 9 so that the projection 15 penetrates the niche 12 while the slider 28 and the spring 21 are radially locked by the wall 10. The sleeve 4 is fastened to the tubular end portion 9 by bending the fins 14 and by means of indentations of the same tubular end portion 9. When the sleeve 4 is completely inserted into the tubular end portion 9, with its bent rim 16 abutting against the rim 19, the slider 28 is positioned below the slot 13. The pushbutton 36 is then fastened to the slider 28 by causing the wings 37 to penetrate through the slot 13 and snap-on couple the inner small teeth 38 to the recesses of the narrow portion 20. According to a further embodiment, after the sleeve 4 has been mounted over the inner tube, the tubular end portion 9 of the outer tube 3 is partially mounted over the sleeve 4. Then, the inner tube 2 and the outer tube 3 are inserted into respective couples of jaws of an assembling machine (not shown). Afterwards, the small plate 23, the slider 28 and the spring 21 are placed into the hollow 18 of the sleeve 4 and the spring 21 is compressed so that the slider and the spring 21 are fully housed inside said hollow. Then, the jaws of said assembling machine are caused to advance one towards the other so that the inner tube 2 and the sleeve 4 are inserted into the outer tube 3. The sleeve 4 fully penetrates the tubular end portion 9 and is centered in the outer tube 3 thanks to the cooperation of the projection 15 with the niche 12 of the relief 1 1. Then the sleeve 4 is fastened to the tubular end portion 9 and the pushbutton 36 is fastened to the slider 28 according to the assembling steps described above. Figures 8 and 9 show a variant of the extension of Fig. 1 , referred to as 41 , in which the same parts are marked with the same reference numerals. In the telescopic extension 41 , a tubular end portion 49 is a piece separate from the outer tube 3 and has an internal diameter larger than the outer diameter of the outer tube 3. A sleeve 44 is fitted over the outer tube 3 and interposed between said tube 3 and the tubular end portion 49. The sleeve 44 is fastened to the tube 3 by means of partially elastic tangs engaging corresponding openings in the tube 3, as in the telescopic extension of EP-B1 -0 601 620. A partially elastic tang 42 is provided with a protrusion 34 which penetrates an opening 43 in the outer tube 3 and engages a longitudinal groove 35 of the inner tube 2. The tubular portion 49 is fastened to the sleeve 44 by bent fins 14 and indentations (not shown). Also in the extension 41 the slider 28 is a piece separate from the pushbutton 36 and has a lengthened and flattened shape. The pushbutton 36 is fastened to the slider 28 by means of wings 37 and inner small teeth 38 which penetrate a slot 13 in the tubular end portion 49. The extension 41 is assembled by a method similar to that described in relation to the extension 1. The sleeve 44 is fitted over the outer tube 3. Afterwards the small plate 23 having integral cylinder 22 and pin 24, slider 28 and spring 21 are mounted completely flush in the hollow 18 of the sleeve 44. The tubular end portion 49 is then fitted over the sleeve 44 and fastened to said sleeve. Finally, the pushbutton 36 is fastened to the slider 28 by causing the wings 37 to penetrate the slot 13 and snap-on couple the inner small teeth 38 into the recesses of the narrow portion 20.

Claims: CLAIMS 1. A telescopic extension (1 ; 41) for a household appliance comprising an inner tube (2) and an outer tube (3) sliding tightly within each other, a sleeve (4; 44), a constraining means (5) capable of fastening said inner and outer tube (2, 3), a thrust element (6) in engagement with said constraining means (5) under the action of spring means (21 ), and actuating means (7) operatively connected to said thrust element (6), said inner tube (2) being provided with a row of notches (8) of preselected shape, a tubular end portion (9; 49) provided with a slot (13) being associated with said outer tube (3), said sleeve (4; 44) being fastened to said tubular end portion (9; 49), said constraining means (5), thrust element (6) and spring means (21 ) being movably supported in said sleeve (4; 44), said thrust element (6) acting on said constraining means (5), under the action of said spring means (21 ), to force said constraining means (5) into one notch (8) to lock said inner tube (2) in said outer tube (3), said actuating means (7) being capable of disengaging said thrust element (6) from said constraining means (5) to let said constraining means (5) exit from said notch (8) and unlock said inner tube (2) from said outer tube (3), allowing the inner tube (2) to slide in respect of said outer tube (3) for adjusting the length of said extension, said actuating means (7) being a piece separate from said thrust element (6) and having protruding wings (37) capable of penetrating said slot (13), characterised in that said tubular end portion (9; 49) has a relief (1 1) forming a niche (12) and said sleeve (4; 44) is provided with a projection (15) which is inserted in said niche (12) and has a hollow (18) wherein said constraining means (5), thrust element (6) and spring means (21 ) are completely housed, said thrust element (6), in turn, is formed by a lengthened, flattened slider (28) provided with a narrow portion (20) having recesses and said protruding wings (37) of said actuating means (7) are provided with inner small teeth (38) capable of being snap-on coupled with said recesses. 2. A telescopic extension (1 ; 41 ) according to claim 1 , characterised in that sad slider (28) is further provided with a blind hole (31 ) capable of partially housing said spring means (21 ) and an inclined wall (29) capable of engaging said constraining means (5). 3. A telescopic extension (1 ; 41 ) according to claim 1 , characterised in that said actuating means (7) are in the form of a pushbutton (36). 4. A telescopic extension (1 ; 41 ) according to claim 1 , characterised in that said constraining means (5) is capable of moving in a substantially radial direction within said hollow (18) of said sleeve (4; 44). 5. A telescopic extension (1 ; 41 ) according to claim 1 , characterised in that said sleeve (4; 44) has a bent rim (16) and is positioned longitudinally inside said tubular end portion (9) by means of said bent rim (16) . 6. A telescopic extension (1 ; 41 ) according to claim 1 , characterised in that said slot (13) is formed in an upper wall (10) of said relief (1 1), and that said slider (28) and spring means (21) are completely flush- mounted in said hollow (18) inside said upper wall (10) of said relief (1 1). 7. A telescopic extension (1 ; 41 ) according to the claim 1 characterised in that said tubular end portion (9) is integral with said outer tube (3) and has the same internal and outer diameters as said outer tune (3). 8. A telescopic extension (1 ; 41 ) according to the claim 1 , characterised in that said slotted hole (13) is equipped with protruding fins (14) suitable for being bent back to lock said sleeve (4; 44) inside said tubular end portion (9; 49). 9. A telescopic extension (1 ; 41 ) according to claims 1 and 4, characterised in that said constraining means (5) is formed by a small cylinder (22) integral with a small plate (23) provided with a pin (24), said hollow (18) having a ramp (26) on which said small plate (23) rests and a cavity (25) in which said pin (24) is rotatably supported. 10. A telescopic extension (1 ; 41 ) according to claims 1 and 9, characterised in that said hollow (18) is provided with an opening (27) which allows said small cylinder (22) to move in a substantially radial direction to engage said notch (8) of said inner tube (2) and to disengage from said notch (8). 1 1. A telescopic extension (1 ; 41 ) according to claim 1 , characterised in that said tubular end portion (49) is a piece separate from said outer tube (3) and has an internal diameter greater than the external diameter of said outer tube (3), said sleeve (44) being interposed between said outer tube (3) and said separate tubular end portion (49). 12. A method for assembling a telescopic extension (1 ; 41 ) for a household appliance, comprising an inner tube (2), an outer tube (3), a sleeve (4; 44), a constraining means (5) capable of fastening said inner tube (2) and outer tube (3), a thrust element (6), actuating means (7) and spring means (21), said inner tube (2) being provided with a row of notches (8) having a preselected shape, a tubular end portion (9; 49) provided with a slot (13) being associated with said outer tube (3), said actuating means (7) being a piece separate from said thrust element (6) and having protruding wings (37) capable of penetrating said slot (13), where said method comprises the following steps: a) fitting said sleeve (4; 44) over one of said inner tube (2) and outer tubes (3), b) movably placing said constraining means (5), thrust element (6) and spring means (21 ) in said sleeve (4; 44), c) inserting said inner tube (2) in said outer tube (3) so as to tightly slide one within the other and inserting said sleeve (4; 44) in said tubular end portion (9; 49), and d) inserting said wings (37) of said actuating means (7) in said slot (13) of said tubular end portion (9; 49), characterised in that e) in step b), said constraining means (5), thrust element (6) and spring means (21 ) are completely housed into a hollow (18) of a projection (15) of said sleeve (4; 44), f) in step c), said sleeve (4; 44) is centered in respect of said outer tube (3) by means of said projection (15) which fits a niche (12) of a relief (1 1 ) of said tubular end portion (9; 49), and g) in step d), inner small teeth (38) of said wings (37) are snap on coupled to recesses of a lengthened, flattened slider (28) which forms said thrust element (6) so that said actuating means (7) are fastened to said thrust element (6). 13. A method according to claim 12, characterised in that, said sleeve (4; 44) is longitudinally positioned inside said tubular end portion (9; 49) by means of an own bent rim (16). 14. A method according to claims 12 and 13, characterised in that said sleeve (4; 44) is locked in said tubular end portion (9; 49) by bending back protruding fins (14) of said slot (13).

Inventors: CANALE GIUSEPPE, CANALE, GIUSEPPE
Applicants: CANALE GIUSEPPE, OMEC SPA, CANALE, GIUSEPPE, OMEC S.P.A.
Application year: 1998
Main classification: A47L9
IPC codes: A47L9