Abstract:
A domestic vacuum cleaning appliance including a flexible hose in which a length of the hose has a hose-wall formed at least in part by a layer of ripstop fabric. In one embodiment, the hose-wall is formed entirely by one or more layers of fabric, including said layer of ripstop fabric, and at least one of the layers of fabric is sealed for preventing escape of fluid through the hose-wall during normal use of the hose. The hose offers an alternative to the conventional corrugated plastic hose commonly used in domestic vacuum cleaners.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of UK Application No. 0912836.4, filed Jul. 23, 2009, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to surface cleaning appliances that incorporate a flexible suction- or blow-hose, possibly provided as part of a hose and wand assembly, in particular to a domestic cleaning appliance and, in a narrower aspect of the invention, to a domestic vacuum cleaning appliance, specifically. 
       BACKGROUND OF THE INVENTION 
       [0003]    Domestic vacuum cleaners, namely those vacuum cleaners which are intended for domestic use, generally fall into two categories: “cylinder” cleaners and “upright” cleaners. 
         [0004]    In a typical cylinder cleaner a, shown in  FIG. 1 , a main body b of the cleaner a is fluidly connected to a floor tool c via a hose and wand assembly. The hose and wand assembly consists of a relatively in-extendable, flexible hose d which is connected at one end to a suction inlet on the main body b, and a rigid, hollow, telescopic wand e which connects the opposite end of the flexible hose d to the floor tool c. During normal operation of the cleaner a, a user grasps the wand e manually to maneuver the floor tool c across the floor, dragging the main body b behind with the in-extendible, flexible hose d. 
         [0005]    In a typical upright cleaner f, shown in  FIG. 2   a , a cleaner head g is permanently attached to the main body h of the vacuum cleaner and the user maneuvers the cleaner head g and the main body h together across the floor using a handle i. Historically, only cylinder cleaners were provided with a suction hose: upright cleaners relied solely on the cleaner head permanently attached to the main body of the cleaner. More recently, manufacturers have started to provide upright vacuum cleaners with a hose and wand assembly, in addition to the cleaner head, so that the upright cleaner can optionally be operated in the manner of a cylinder cleaner.  FIG. 2   b  shows a particularly compact form of hose and wand assembly, used generally on models from the Dyson range of upright vacuum cleaners, in which a telescopic wand j is integrated with the handle i and can be released from the main body by operating a catch. A so-called “stretch” hose k attaches the wand j to a suction inlet (not shown) on the main body h; the stretch hose k is stored on-board the main body h in a retracted position and can then be manually extended, or “stretched”, as desired following release of the wand j (with the handle i) in order to increase the useful reach of the wand j. A suitable floor tool l can be attached to the suction inlet on the wand j, as desired. 
         [0006]    Hoses for early models of cylinder cleaner were often constructed using rubber, an example of which is described in UK Patent No. GB836407. These rubber or rubber-based hoses were, however, superseded relatively quickly by plastic suction hoses, typically comprising a molded thermoplastic hose wall having a series of corrugations to provide the requisite flexibility for the hose. The use of plastic significantly reduces the weight of the hose compared to a corresponding rubber or rubber-based hose, and the molded plastic suction hose has become the well-established industry norm for domestic vacuum cleaners, whether in the form of relatively in-extendible hoses for cylinder cleaners or as stretch hoses for modern upright cleaners. 
         [0007]    Molded plastic hoses are also commonly used as a suction or blow pipe in industrial (non-domestic) surface-cleaning appliances, and are used in other fields in which it is likewise desirable to provide a hose which is relatively lightweight and low-cost to produce. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to seek to provide a domestic cleaning appliance having an improved flexible hose, possibly incorporated as part of a hose and wand assembly for the appliance, which offers an advantageous alternative to the conventional molded plastic hose used on domestic vacuum cleaners. 
         [0009]    According to the present invention, there is provided a domestic cleaning appliance, and in a narrower aspect a domestic vacuum cleaning appliance, having a flexible hose in which a length of the hose has a hose-wall formed at least in part by a layer of ripstop fabric. 
         [0010]    Ripstop fabric is a fabric which is interwoven with a pattern of reinforcing yarns, typically a cross-hatch pattern, and which consequently exhibits high resistance to the formation and spread of tears and runs in the fabric. The ripstop fabric may be ripstop polyamide (nylon) or ripstop polyester, but the invention is not limited to any particular fabric. The reinforcing yarns in the ripstop fabric do not necessarily need to be the same material as the bulk fabric. 
         [0011]    The layer of ripstop fabric constitutes a relatively tear- and puncture-resistant layer in the hose wall. The layer of ripstop fabric itself may be relatively thin, possibly less than 0.1 mm in the case of a hose for a domestic vacuum cleaning appliance, and therefore does not add any significant weight to the hose. The ripstop fabric is also highly flexible. 
         [0012]    The use of a flexible hose on a domestic vacuum cleaning appliance in particular, such as a cylinder or upright vacuum cleaner, advantageously breaks with the long-established norm of utilizing a hose having a molded plastic hose-wall. In a conventional molded plastic hose, a puncture in the hose-wall can expand relatively quickly if the hose continues to be used, eventually resulting in a critical reduction in the pressure differential across the ends of the hose (noticed by the user as a loss of suction). In the hose according to the present invention, however, the resistance of ripstop fabric to the spread of tears and runs means that if the hose is punctured, the puncture will tend not to expand, or at least not as rapidly—the tear effectively being contained by the pattern of reinforcing yarns in the ripstop fabric. Consequently, following a puncture to the layer of ripstop fabric, a user may nevertheless be able to continue using the hose without any further appreciable loss in suction, at least until the hose can be permanently repaired or replaced. Containment of the puncture in the ripstop fabric may also allow for an effective, superficial, temporary repair of the puncture, for example using an adhesive patch. 
         [0013]    The hose may be provided on the appliance as part of a hose and wand assembly. 
         [0014]    The layer of ripstop fabric may be sealed so that it forms an impermeable layer for preventing escape of fluid through the hose-wall. Such sealing of the ripstop fabric layer may be by coating or impregnation of the layer of ripstop fabric with a sealant or, specifically where the ripstop fabric is woven from plastic, by plastification of the layer of ripstop fabric if appropriate. Care should be taken, during the plastification process, to retain the ripstop structure of the fabric. 
         [0015]    If the layer of ripstop fabric is sealed, the layer of ripstop fabric then advantageously provides a dual function, in that it both reduces the formation and spread of punctures in the hose-wall, while also acting as an impermeable barrier to the hose fluid. Consequently, there is no requirement to provide a separate, impermeable layer as part of the hose-wall, such as a separate layer of molded thermoplastic. 
         [0016]    The hose-wall may be supported on one or more frame elements, providing increased crush strength and stiffness for the hose. This helps to maintain an open flow passage through the hose. Increased stiffness may be particularly desirable in a hose for a domestic cylinder cleaner, because in cylinder cleaners it is also preferable that the hose is sufficiently stiff for guiding or “leading” the main body of the cleaner across the floor. The frame elements may take various forms; for example, they may be in the form of successive coils on a helical supporting member, which may be a helical metal wire, or in the form of longitudinal, flexible ribs or separate frame rings. 
         [0017]    The hose-wall may be a fabric hose-wall, i.e. consist of one or more layers of fabric, including said layer of ripstop fabric, in which case at least one of the layers of fabric is sealed so that it forms an impermeable layer for preventing escape of fluid through the hose-wall during normal use of the hose. Again, sealing of the fabric may be by impregnation or coating with a sealant, or by a suitable plastification process, as appropriate. 
         [0018]    It is intended that a hose having a fabric hose-wall will offer a lightweight alternative to the conventional molded plastic hose. The weight per unit length of the hose will depend upon the thickness of the fabric wall (and to an extent on the method of sealing), but it is envisaged that sufficient puncture resistance for a hose used in a domestic surface cleaning appliance can be achieved with a reduction in weight per unit length as compared to a conventional molded plastic hose. 
         [0019]    One or more of the frame elements may be sandwiched radially in-between either two separate layers of fabric in the hose wall or, alternatively, two plies of fabric (which may be formed by doubling over a single layer of fabric), so that the frame element(s) is (are) not exposed on the outside of the hose wall. 
         [0020]    During use of the hose, frictional wear of the fabric may occur, principally along the contact interface between the frame elements and the fabric, which may eventually lead to breach of the hose wall (and consequent loss of suction in the case of a suction hose for a surface cleaning appliance). The provision of two sandwiching layers or plies of fabric reduces the effect of this frictional wear by increasing the effective thickness of the hose wall. At the same time, providing the inner sandwiching layer (or ply) on the inside of the frame element has the advantage that this inner sandwiching layer is not exposed to the relatively high levels of frictional wear which typically occur around the outside of the frame elements. 
         [0021]    The layers or plies of fabric may be bonded to one another, axially either side of the respective frame element, to encapsulate the frame element between the layers or plies of fabric, thus conveniently retaining the frame elements in their predetermined positions. The fabric making up the hose wall may additionally or alternatively be arranged to form a multi-ply or multi-layer overlap around the outside of one or more of the frame elements, further improving the external wear resistance of the hose. 
         [0022]    It has also been found that coating the frame elements with a relatively compliant or low-friction material (i.e. compliant or low-friction relative to the material making up the frame elements) has a significant effect on the wear resistance of the hose. For example, if the frame elements are steel, the wear resistance of the hose can be improved significantly by coating the frame elements with a plastic e.g. polyurethane (PU), thermoplastic polyurethane (TPU), polyethylene terephthalate (polyester) or polytetrafluoroethylene (PTFE) 
         [0023]    The hose wall may comprise a wound fabric tape. In a particular embodiment, the hose wall comprises a wound fabric tape, and one or more of the frame elements are sandwiched radially in-between two axially-overlapping passes of the wound fabric tape. The respective overlapping passes of the fabric may be bonded to one another, axially either side of the corresponding frame element in order to encapsulate the frame element. Additionally or alternatively, the wound fabric tape may be arranged so that two or more axially overlapping passes if the fabric tape form a respective multi-ply overlap around the outside of one or more of the frame elements. These winding arrangements are considered to be particularly effective for reducing the effects of frictional wear; this is particularly the case during use on a typical domestic vacuum cleaning appliance, where preliminary tests indicate that winding a ripstop fabric tape in the manner described above can dramatically increase the life of the hose compared to a conventional molded plastic hose. The winding arrangements described above also present a relatively smooth internal surface to the hose, tending to reduce the thickness of any boundary layer flow through the hose. 
         [0024]    The hose-wall may be bonded to the frame elements, for example using an adhesive. If the frame elements are formed from an electrically conductive material, the adhesive may be cured by resistance-heating the frame elements. 
         [0025]    Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a schematic, perspective view of a conventional cylinder cleaner incorporating a flexible suction hose; 
           [0027]      FIGS. 2   a  and  2   b  are schematic, side views of a conventional upright cleaner incorporating a flexible suction hose; 
           [0028]      FIG. 3  is a schematic perspective view of a retracted length of flexible, extendable hose in accordance with the present invention; 
           [0029]      FIG. 4   a  is a sectional view of the hose shown in  FIG. 3 , taken along the line A-A; 
           [0030]      FIG. 4   b  is a sectional view corresponding to  FIG. 4   a , but showing the hose in an extended configuration; 
           [0031]      FIG. 5  is a sectional view showing an alternative form of hose in accordance with the present invention, in which the hose wall has a multi-layer fabric construction; 
           [0032]      FIG. 6  is a sectional view showing an alternative form of hose, in which the hose wall is constructed from wound fabric tape; 
           [0033]      FIG. 7  is a sectional view through part of the fabric hose wall shown in  FIG. 6 ; 
           [0034]      FIG. 8  is a sectional view through a length of hose, illustrating an alternative hose wall configuration utilizing a wound fabric tape; and 
           [0035]      FIG. 9  is a sectional view through a length of hose, illustrating a further alternative hose wall configuration utilizing a wound fabric tape. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    Referring first of all to  FIG. 3 , an extendable length of hose  1  comprises a hose-wall  2  which is supported on the outside of a helical supporting member  3  (shown in phantom in  FIG. 3 ). 
         [0037]    The helical supporting member  3  is resiliently extendable lengthways (along the axis x in  FIG. 3 ) from a retracted length L r , shown in  FIG. 4   a , to an extended length L e , shown in  FIG. 4   b.    
         [0038]    The hose wall  2  consists of a single layer of ripstop fabric, for example ripstop nylon or ripstop polyester, which is sealed to prevent escape of fluid through the hose-wall  2 . The hose-wall  2  thus represents an impermeable barrier for containing a fluid under transport, indicated by the flow arrow A through the hose  1  in  FIG. 4   b.    
         [0039]    The fabric hose-wall  2  is secured to the helical supporting member  3 , but is provided with sufficient axial slack to accommodate substantially non-elastic lengthways extension from the retracted length L r  to the extended length L e . Thus, with the helical supporting member  3  at its retracted length L r , the fabric hose-wall forms a series of corrugations in between the successive coils of the helical supporting member  3 , which corrugations are then taken up during lengthways extension of the hose-wall to the extended length Le, as illustrated in  FIG. 4   b . The fabric hose-wall  2  may be arranged to fold along pre-determined lines, so that the hose-wall tends to form a series of tighter, predefined folds between successive coils, of the helical supporting member  3  rather than the more ‘loose’ corrugations shown in  FIG. 4   a.    
         [0040]    The fabric hose wall  2  may be sealed by impregnating, spray-coating or dip-coating the ripstop fabric with a sealant such as polyurethane (PU), a thermoplastic polyurethane (TPU) or polyvinyl chloride (PVC), or in general by using any suitable plastification process. 
         [0041]    The ripstop fabric may be sheet fabric, produced for example by weaving, braiding or knitting, in which case the sheet fabric may be wrapped around the outside of the helical supporting member  3  to form the tubular hose-wall  2 . The fabric may be wrapped tightly to form a compression-fit on the helical supporting member  3  (while still having the necessary axial slack for lengthways extension of the hose wall  2 ). The hose-wall  2  may be securely bonded to the helical supporting member  3 , for example using a heat-curable adhesive such as a suitable solvent-based or epoxy adhesive, which may be applied to one or both of the hose-wall  2  and the helical supporting member  3 , possibly as a pre-coating prior to wrapping of the fabric. If the helical supporting member  3  is in the form of a coil of metal wire, the adhesive may conveniently be heat-cured by resistance-heating the wire using a suitable electric current. 
         [0042]    In an alternative arrangement, the ripstop fabric is produced as a seamless, tubular fabric, produced for example by tubular-weaving, tubular-braiding or tubular-knitting, and the hose-wall  2  is formed by rolling the ripstop fabric tube lengthways onto the helical supporting member  3 . A pre-form ripstop fabric tube may also be produced from sheet fabric by initially wrapping the fabric around a cylindrical mandrel and bonding the sheet fabric along a seam to form the tube. Again, the relative diameter of the hose-wall  2  may be controlled to form a slight compression-fit on the helical supporting member  3  and the hose-wall may be securely bonded to the helical supporting member  3  using a heat-curable adhesive. 
         [0043]    In  FIGS. 4   a  and  4   b , successive coils  3   a ,  3   b ,  3   c  of the helical supporting member  3  constitute a continuous set of frame elements for supporting the hose-wall  2 .  FIG. 5  shows an alternative arrangement, in which a length of hose  10  has a hose-wall  20  supported on a non-continuous set of frame elements, in the form of individual frame rings  30  bonded separately to the inside of the hose-wall  20 . 
         [0044]    The hose-wall  20  has a multi-layer fabric wall construction, consisting of an intermediate layer of ripstop fabric  20   a  sandwiched between separate inner and outer layers of fabric  20   b ,  20   c . The layers of fabric  20   b ,  20   c  may be ripstop fabric or some other fabric intended to impart a desirable property to the hose wall e.g. chemical or fire resistance. The fabric layers  20   a ,  20   b ,  20   c  may be non-elastic, in which case the length of hose  10  will be extendable to an extent determined by the elasticity of the hose wall  20 ; alternatively, at least one of the layers  20   a ,  20   b ,  20   c  may be inelastic, in which case the length of hose  10  will be substantially in-extendible. The hose  10  may also be configured to be substantially incompressible, as desired, for example by rigidly connecting the frame elements using a rigid spine member  31 , shown in phantom in  FIG. 5 . 
         [0045]    Each of the layers of fabric  20   a ,  20   b ,  20   c  may be formed from either sheet fabric or tubular fabric. For example, the fabric layer  20   a  may be formed as a seamless, tubular fabric, and the layers  20   b  and  20   c  may be formed from sheet fabric which is successively wrapped around the inner, tubular fabric layer  20   a . The fabric layers  20   a ,  20   b ,  20   c  may be bonded to one another using a heat-curable adhesive, which may be cured by resistance-heating each frame ring  30  separately, possibly using some sort of switching circuit. Alternatively, where sealing of the layer or layers of fabric,  20   a ,  20   b ,  20   c  is by impregnation, the impregnating sealant may also be used effectively to bond the fabric layers  20   a ,  20   b ,  20   c.    
         [0046]      FIG. 6  is a sectional view illustrating a multi-layer fabric hose wall formed using two ripstop fabric tapes  200  and  201 . 
         [0047]    Each of the fabric tapes  200  and  201  is wound around to form a respective fabric layer along the length of the helical supporting member  3 . In the case of the fabric tape  200 , this forms a respective fabric layer  210  on the outside of the helical supporting member  3  consisting of a series of axially-overlapping passes of fabric  200   a ,  200   b ,  200   c  etc. In the case of fabric tape  201 , this forms a respective fabric layer  211  on the inside of the helical supporting member  3  consisting of a series of overlapping passes of fabric  201   a ,  201   b ,  201   c  etc. 
         [0048]    The coils  3   a ,  3   b ,  3   c  etc. of the helical supporting member  3  are sandwiched radially in-between the two fabric layers  210 ,  211 . For example, the coil  3   a  is sandwiched between the passes  200   a ,  201   a , the coil  3   b  is sandwiched between the passes  200   b ,  201   b  and so on. In addition, overlapping passes of the fabric tape  200  form a series of double-ply overlaps on the outside of the coils  3   a ,  3   b ,  3   c  etc. For example, the overlapping passes  200   a  and  200   b  form a double-ply overlap on the outside of the coil  3   a , the overlapping passes  200   b  and  200   c  form a double-ply overlap on the outside of the coil  3   b  and so on. In the arrangement shown in  FIG. 6 , overlapping passes of the fabric tape  201  additionally form corresponding double-ply overlaps on the inside of the coils  3   a ,  3   b ,  3   c , but the double-ply-overlaps on the outside of the helical supporting member  3  are considered to be particularly advantageous for a suction hose on a domestic cleaning appliance, because they are associated with regions of the hose-wall that are typically subject to relatively high frictional wear. 
         [0049]    The fabric tapes  200 ,  201  may be pre-wound on a mandrel and then fitted onto the helical supporting member  3  in similar manner to a pre-form fabric tube, possibly following bonding of the overlapping passes of fabric to consolidate the pre-wound configuration of the fabric tape. 
         [0050]    The overlapping passes  200   a ,  201   a  are bonded to one another axially either side of the coil  3   a , as indicated by the vertical dotted lines in  FIG. 7 , in order to encapsulate the coil  3   a  between the fabric tapes  200 ,  201 . In addition, the passes  200   a ,  201   a  are bonded respectively to the passes  200   b ,  201   b.    
         [0051]      FIG. 6  illustrates one possible winding arrangement using fabric tape, but other arrangements are possible. Thus, in  FIG. 8 , a single ripstop fabric tape  203  is wound onto the helical supporting member  3 , along the direction x, with a trailing portion of the fabric tape  203  running around the outside of the coils  3   a ,  3   b ,  3   c  and a leading portion of the fabric tape  203  running around the inside of the coils  3   a ,  3   b ,  3   c . In this case, each of the coils  3   a ,  3   b ,  3   c  is sandwiched radially in-between overlapping passes of the single fabric tape  203 , without the need for a second fabric tape. For example, the coil  3   b  is sandwiched between overlapping passes  203   a  and  203   b , which may be bonded to one another axially either side of the coil  3   b  in order to encapsulate the coil  3   b  in position. 
         [0052]    A single ripstop fabric tape may be wound additionally to form a multi-ply overlap on the outside of a frame element.  FIG. 9  illustrates one such “dual function” winding arrangement; the arrangement shown in  FIG. 9  is similar to the arrangement shown in  FIG. 8 , but utilizes a relatively wide ripstop fabric tape  204  additionally to form a series of double-ply overlaps on the outside of the coils  3   a ,  3   b ,  3   c . In this case, the ripstop fabric tape  204  is arranged such that each of the coils  3   a ,  3   b ,  3   c  is sandwiched radially in-between first and second overlapping passes of the fabric tape  204 , while the second overlapping pass additionally overlaps a third pass of the fabric tape  204  to form a double-ply layer overlap on the outside of the coil. For example, the coil  3   a  is sandwiched between successive overlapping passes  204   a  and  204   b , while pass  204   b  additionally forms a double ply overlap with successive overlapping pass  204   c . The overlapping passes  204   a  and  204   b  may be bonded to one another axially either side of the coil  3   a  to encapsulate the coil in position. In addition, the overlapping passes  204   b  and  204   c  may be bonded to one another in the region of the respective double-ply overlap. 
         [0053]    Although in the embodiments described, the frame elements are located on the inside, or encapsulated within, the hose-wall, the invention is not intended to be limited to such arrangements and the frame elements may alternatively be provided on the outside of the hose wall. 
         [0054]    The invention concerns a domestic cleaning appliance, preferably a domestic vacuum cleaning appliance, in which case the hose may be incorporated as part of a hose and wand assembly for the appliance, and in any event may be fitted to a main body of the appliance using conventional fittings. The main body of the appliance may in particular be a conventional cylinder body on a domestic cylinder cleaner, such as the main body b in  FIG. 1 , or may be a conventional upright body on a domestic upright cleaner, such as the main body h in  FIGS. 2   a  and  2   b.    
         [0055]    Although in the embodiments described the hose incorporates a fabric hose-wall i.e. a hose wall constructed entirely from one or more layers of fabric, in its broadest sense the invention is not limited to arrangements wherein the stretch hose has a fabric hose-wall. The hose wall may, for example, additionally incorporate an extruded or injection-molded plastic protective sheath or lining. Nevertheless, it is believed that the use of a layer of ripstop fabric having a relatively high resistance to the formation of spreads and tears can improve the useful life of the hose as compared to a conventional molded-wall plastic hose.