DUST VACUUM CLEANERS AND HOSES
Field of the Invention This invention relates to dust vacuums of the type that include a suction unit and a flexible hose assembly. BACKGROUND OF THE INVENTION Cylinder dust vacuums are used with a hose. Vertical dust vacuums could also be used with a hose where it is necessary to clean in less accessible locations. Hoses are also used in central dust extraction installations, where a suction unit and a pipeline are constructed inside a building or construction. A long hose is useful in some situations although it causes problems with its storage and handling. The length of a hose is usually an arrangement between the long extension that facilitates and employs a short extension for easy storage. One form of hose that can be long and still easy to store is the stretch or stretch hose, which has a naturally short length but can be pulled to extend it to a longer length. The hose has a helical reinforcement with a natural contracted length although it can be stretched elastically. Although these hoses can be used in a
REF.172094 satisfactory, they have a disadvantage due to the force required to extend the hose and the maintenance of its extension makes it more difficult to manipulate the cleaning head. In addition, the force could pull or move the vacuum cleaner or any furniture around which the hose is directed. One solution for this is the hose capable of being retracted which has a naturally extended length and which can be retracted by suction. This is achieved by selecting the elasticity of the helical reinforcement of the hose, so that the suction created by the dust vacuum, when the far end of the hose is obstructed, is sufficient to pull the hose to a retracted length. Then, the hose is kept in its retracted state, so that it does not extend when the dust vacuum is turned off. This form of hose capable of being retracted is described in WO 03/024294. Although this form of hose has many advantages, there may be situations where it is desirable to have a hose that can be extended even at longer lengths without an increase in storage length, or where the construction of the hose does not allow it to be extended. it is retracted by suction, or where a hosel form that can be retracted is preferred. SUMMARY OF THE INVENTION An object of the present invention is to provide an alternative dust and hose vacuum. According to one aspect of the present invention, a dust vacuum cleaner of the type specified above is provided, characterized in that the hose assembly includes at least two flexible sections, one of which has an outer diameter smaller than the other and can to slide within the other, and the two sections are positioned to seal each other at least when the two sections are extended relative to each other. Preferably, the flexible sections are corrugated. The smaller diameter section can be stretched from a short natural length to a longer extension by applying an axial force. Alternatively, the smaller diameter section may be retracted from an extended natural length to a shorter extension, by suction applied by the suction unit when the end of the hose assembly is capped. The shorter length of the smaller diameter section could be substantially equal to the length of the longest diameter section. The two sections of the hose assembly could be provided with cooperating couplings that can be clutched together to hold the two sections in a compact configuration one inside the other for storage. The longer diameter section of the hose assembly can be stretched from a short natural length to a longer extension by applying an axial force. According to another aspect of the present invention, a hose assembly for a dust vacuum is provided, characterized in that the hose assembly includes the corrugated flexible sections, both internally and externally, the inner section having a first end held in a sliding manner within the outer section, the assembly of The hose has a short configuration in which the greater part of the length of the inner section extends into the outer section and the first end of the inner section is located adjacent to the first end of the outer section, and the hose assembly has a longer configuration wherein the inner section is extended beyond a second end of the outer section and the first end of the inner section is located adjacent the second end of the outer section and in which a seal is provided between the two sections . Preferably, the inner section is extendable from a shorter length that is substantially equal to the length of the outer section to a longer extension that is larger than the extension of the outer section. BRIEF DESCRIPTION OF THE DRAWINGS Next, a dust vacuum including a hose assembly and its method of use, in accordance with the present invention, will be described, by way of example, with reference to the accompanying drawings, in which : Figure 1 is a simplified perspective view of the vacuum cleaner and the hose assembly in an extended state; and Figure 2 is a simplified cross-sectional simplified view of a portion of the hose assembly in an extended state. Detailed Description of the Invention First reference to Figure 1 shows a dust vacuum including a suction unit 1, a hose assembly 2 and a cleaning rod 3 with a cleaning head 4 at one end. Unit 1 is a conventional vacuum that is of the portable cylinder type with a pump, a dust collection bag, controls and filters of the usual type (not shown). The unit 1 has a suction inlet 10 towards one end in which the hose assembly 2 is connected. Next, with reference also to Figure 2, the hose assembly 2 has a first outer section 20 with a coupling 21 in an end connected to the suction inlet 10. The main part of the first section 20 is provided by a flexible and corrugated tubular wall 22 of a plastic material, which is reinforced by a helical wire 23. The invention can also be applied to other forms of hose, such as those made entirely of plastic. The end of the first distal section 20 of the dust suction housing 1 is terminated by a sealing coupling 24. The first section 20 of the hose assembly 2 has a length typically around 1.8 m and is relatively inextensible in the axial direction. The first hose section 20 could alternatively be a stretch construction, ie one having a short natural length retracted although it can be pulled by applying an axial force to a longer extension against the axial elasticity of the hose. The hose assembly 2 also has a second smaller diameter inner section 25, which is flexible and corrugated and is provided by a sleeve 26 of a highly flexible plastic material supported on the outside of the helical reinforcement member in the form of a spring metal wire 27 as described in WO03024294. The helical reinforcing wire 27 has an extended natural state although it can be compressed in the axial direction against its elasticity by an applied external force. The sleeve 26 is sufficiently flexible so that the second section 25 itself naturally takes the extended length of the reinforcing wire helix 27. The sleeve 26 has shallow rises extending outwardly between the turns of the reinforcing wire 27 , which allows the sleeve to fold out when the hose is retracted. The second section 25 is terminated at one end by a rigid circular end fitting 28 located within the first larger diameter section 20 and which can freely slide along it. The dimensions of the end fitting 28 and the coupling 24 in the first section are to prevent extraction or separation of the end fitting. End fitting 28 and coupling 24 have clutch sealing surfaces 29 and 30 that extend in the lateral direction and abut and seal each other when the end fitting is pulled against the coupling. The extended natural length of the second section 25 is approximately 3.6 m and can be retracted to a length approximately the same as the length of the first section, ie, about 1.8 m. This provides a maximum total length of approximately 5.4 m. In general, - if both sections of the hose can not be retracted or compressed, the total minimum length of the hose will be approximately 50% of its maximum length. Where 'one of the hose sections can be retracted, as described above, the same maximum length can be achieved although the minimum length can only be about 25% of the maximum. The opposite end of the second section 25 is terminated by a handle 32, such as the type described in GB2403403. The rear end of the handle 32 is formed with a coupling 33 adapted to be connected to the coupling 24 at the end of the first section 20. The handle 32 has an activator 34 that can be operated by the user to close a valve (not shown) ) inside the handle and thereby preventing or restricting the flow of air through the handle and therefore, along the hose assembly 2. The cleaning rod 3 is connected to the leading end of the handle 32. Before of its use, the second section 25 is retracted and withdrawn into the first outer section 20, as shown by the dashed lines in Figure 2, and is maintained in this retracted state by the clutch of the couplings 33 and 24, with which provides a relatively compact configuration for storage. The hose assembly 2 can be used in this compact configuration for cleaning where a longer extension is not necessary. A stretching construction of the first section 20 facilitates use in this compact configuration. However, the user would usually release the two couplings 33 and 24, so that the elasticity of the second section 25 extends to its extended natural length. Next, the user pulls the second section 25 lightly to extract the outside of the first section 20 to its maximum range, in a telescopic mode. Until the end fitting 28 is pulled or pulled inward in a sealing clutch with the coupling 24, the air will be able to flow between the outside of the second section 25 and the coupling in the first section 20, so that The suction effect on the cleaning head will be reduced. Once the end fitting 28 is engaged with the coupling 24, a seal is formed between the surfaces 29 and 30 preventing the escape of air into the hose assembly 2 except in the cleaning head 4. Therefore, the length total of the extended hose assembly 2 is equal to the combination of the length of the first section 20 and the extended length of the second section 25, ie, approximately 5.4 m. It will be appreciated that, if the first outer section 20 had a stretching construction, the total effective length of the entire hose assembly can also be extended by applying a slight pulling force at the remote end of the assembly. When the user has finished cleaning and wishes to store the vacuum, the user closes the activator 34 on the handle 32 to restrict air flow along the hose assembly 2. This creates a suction pressure inside the hose assembly 2 , whereby the second section 25 is retracted in its length. The suction also has the effect of dragging the second section 25 backwards in the direction of the first section 20, telescopically, like a piston. Once the end fitting 28 is displaced from the coupling 24, some air will move towards the first section 20 in the coupling although it is still easy for the user to completely retract the second section 25 towards the first section with the combination of the suction and some e bidding and manual guidance. When the second section 25 has been completely drawn into the first section 20 and has been retracted in its length, the coupling 33 on the handle 32 is engaged with the coupling 24 in the first section. The dust vacuum can now be turned off by allowing the pressure inside the hose assembly 2 to rise into the atmosphere. The tendency of the second section 25 'to extend is restricted by the clutch of the couplings 33 and 24. By supplying the second section 25 which slides within the first section 20, the effective total length of the hose assembly 2 can be further extended with respect to the arrangement described in WO030242 4 without any increase in the housed length of the hose assembly. 0, the same extended length can be achieved with a hose assembly having a reduced length of accommodation or accommodation. The invention could also be used with conventional hoses that can not be extended or retracted in their length. In the simplest case, the user would simply pull out the smaller diameter hose from the larger diameter hose to its full reach when the cleaning is done and push the two hoses together telescopically when the vacuum cleaner goes to be stored. This allows the usable effective length of the hose to be increased by two. times of the hosted length. In a modification of this arrangement using conventional hose sections, the remote end of the hose assembly could have a valve similar to the one described above in which the user can close, so that the suction is created within the hose assembly . The suction helps produce a telescopic piston effect to drag the hose of similar diameter towards the larger diameter hose. It will be appreciated that the hose assembly could have several different configurations. For example, the hose assembly could include three or more hose sections of different diameters nested one inside the other, so that the effective and extended length that can be used of the hose is three times or more the housed length. The longer diameter section could be secured at the remote end of the hose assembly and the smaller diameter section would be secured with the dust vacuum housing. The hose does not need to have a construction reinforced with wire but could be, for example, a low cost hose made entirely of plastic material. The seal between the various sections of the hose need not be provided by supporting the side surfaces but instead could be provided by one or more sliding seals, such as those provided on the outer section that faces inward to make a sliding seal with the outside of the inner section, or the inner section that faces outward to make a sliding seal with the inside of the outer section, or both of these arrangements. The invention is not confined to portable cylinder vacuum cleaners but could be used with vertical vacuum cleaners, central vacuum cleaner installations, fixed garage forecourt dust vacuums, or the like. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.