The present invention relates to a flexible duct for a vacuum cleaner. More specifically, the present invention relates to a flexible duct for a vacuum cleaner tool.

Figures 1 and 2 are examples of flexible crevice tools 100,200 that can be used with a vacuum cleaner. The tools 100,200 are intended to reach into and clean crevices or gaps to be cleaned. Both of the tools shown in Figures 1 and 2 comprise a flexible duct 300 formed from a pliable casing material 400 which is reinforced by a rigid frame 500. Any steering force applied to the tool 100,200 when it is in a crevice causes the pliable casing material 400 to bend. The rigid frame 500 is used to improve the control and steering of the tool in a desired direction, and to prevent the flexible duct 300 from folding over itself or kinking. Folding or kinking of the duct should be prevented as this can restrict the flow of fluid drawn through the tool 100,200, and may also cause damage to the flexible duct 300.

The two examples of crevice tools 100,200 employ two different types of rigid frames 500 in order to improve control and steering of the tool, and to prevent folding or kinking of the duct. A problem with the tool 100 shown in Figure 1 is that the use of a rigid central spine 600 completely restricts the duct from flexing in a particular direction, i.e. the direction of the spine 600. This could be problematic, for example, if a crevice to be cleaned is an irregular shape since the tool may suffer from reduced manoeuvrability in the crevice.

The tool 200 shown in Figure 2 introduces a helical shape frame 700 to improve the flex of the duct. The pliable casing material 400 is free to bend and flex in all directions. The range of flexibility of the duct 300 and its manoeuvrability in the crevice is therefore improved. However, there is still a risk that the pliable casing material 400 could still fold or kink if the regular rotations of the helical frame 700 are spaced too far apart or if the material used for the helical frame 700 is too flexible. The duct frames 500 used in the prior art tools 100,200 therefore present a compromise between the range of flexibility of the duct 300 and the prevention of folding or kinking of the duct 300.

In a first aspect, the present invention provides a vacuum cleaner tool comprising a flexible duct, the flexible duct comprising: a helical frame comprising a plurality of loops arranged about a helical axis and being formed of a rigid material; and a helical strip provided on the loops to seal the frame and being formed of pliable material; wherein at least one loop has one or more projections that extend towards an adjacent loop so as to limit flexing of the flexible duct in a direction normal to the helical axis.

By providing a projection on at least one of the loops of the helical frame, the degree of movement of the flexible duct in directions normal to the helical axis is reduced without being overly constrained. This provides the user with more control of the flexible duct in a desired direction of steering, e.g. left/right direction instead of the duct flexing in an up/down direction. The risk of the user losing control and causing the duct to fold or kink is also reduced since the projections on a loop restrict the amount of movement of the duct in an undesired direction. Consequently, this enables the duct to maintain a high degree of flexibility and manoeuvrability, whilst also reducing the risk of the duct folding or kinking. The restriction of movement also has the additional benefit of reducing the risk of damage caused to the flexible duct by preventing over-flexing in a particular direction.

In terms of the flexing movement, the duct can be said to flex in a left-right direction and in an up-down direction normal to the helical axis. The projections on the loops can be spaced or positioned such that they limit the overall range of movement of the duct in both the left-right direction and the up-down direction. Conversely, they can be arranged so that they restrict the range of movement of the duct predominantly in one direction normal to the helical axis (i.e. either left/right or up/down), relative to the range of movement of the tool in the other direction. The cross section of the flexible duct may be a general rectangular shape, comprising two longer side surfaces connected by shorter top and bottom surfaces. The general rectangular shape of the flexible duct allows for a narrow profile crevice tool that can fit into most gaps and crevices. The requirement of a general rectangular shape does not preclude the curving or shaping of the sides of the rectangular duct for aesthetic or ergonomic purposes.

The projections on the loops may be aligned along the top surface and/or the bottom surface of the flexible duct to limit the movement of the flexible duct in only one direction that is normal to the helical axis, i.e. an up/down direction. By limiting the movement of the flexible duct in a single direction the movement of the flexible duct is less restricted in the other directions normal to the helical axis. By providing the projections along one of the top or bottom surface the manoeuvrability of the duct can be improved. In addition, the amount of material used and the complexity of the part can be reduced whilst still providing a reasonable compromise between duct flexibility and the prevention of folding of the duct. The projections on the loops however can be provided on both the top surface and the bottom surface of the flexible duct. By having projections on the top and the bottom surfaces of the duct the user's control of the duct is improved and the risk of the duct folding or kinking and/or causing damage to itself can be further reduced. For example, if the tool is used to clean a regularly shaped gap or crevice, some force would be applied in an up or down direction relative to the helical axis as the tool is pressed into the floor of the crevice. It is therefore advantageous to reinforce the duct in this direction to prevent miss-steering of the duct and also folding or damage to the tool.

The helical strip may have indents provided on the side surfaces of the flexible duct. The indents allow for improved flexibility of the duct and also provide a crease for the duct to fold into as it flexes.

Each loop may comprise a central band with at least one wing, the helical strip being secured to the at least one wing such that the exterior surface of the helical strip is flush with the exterior and/or interior surface of the central band. The helical strip is used to seal the space between the rigid frame loops and may be in the form of a single piece of material (such as a ribbon or bandage), or a series of interlinked bands that together provide a sealed duct. In other words, the helical strip is used to link the loops of the helical frame. The helical strip may be overmoulded or bonded onto the helical frame. The helical strip also can be provided only between the loops of the helical frame, compared to a full sheath that covers both the frame and the space between the loops of a frame.

The pliable sheaths that are used in the prior art examples are placed over the tool flexible duct to conceal the frame. In contrast to these sheaths, using a single piece of helical strip material means that less material can be used to make a sealed duct. In addition, the helical strip between the loops can be formed so that it is flush with the central band of each loop. This is in contrast to fitting a sheath over the frame and increasing the profile of the tool. Thus, the profile of the tool can be reduced so that it can fit into narrower gaps and crevices without comprising manoeuvrability and the ability to control the tool. Although at least part of the helical frame may be uncovered (i.e. the central band of each loop may appear exposed), the helical strip can be used to cover other parts of the loops. For instance, the wings and the projections on the loops can be concealed by the helical strip. Furthermore, having a duct with a smooth internal surface reduces the amount of losses through turbulence as the airflow is drawn through the duct.

The tool of the present invention may be a telescopic tool comprising a first and second conduit; the first conduit has a narrower profile than the second conduit, the second conduit surrounds the first conduit such that the first conduit slides in and out of the second conduit allowing for extension of the tool, and the flexible duct forms part of the first conduit. The use of the flexible duct on a telescopic tool allows for a longer tool that can be placed into gaps or crevices to be cleaned. Furthermore, the provision of a rigid conduit together with a conduit having the flexible duct improves the handling and manoeuvrability of the tool since the user can hold onto the rigid conduit and steer to the tool.

In a second aspect, the present invention provides a vacuum cleaner duct comprising: a helical frame comprising a plurality of loops arranged about a helical axis and being formed of a rigid material; and a helical strip provided on the loops to seal the frame and being formed of pliable material; wherein at least one loop has one or more projections that extend towards an adjacent loop so as to limit flexing of the duct in a direction normal to the helical axis.

In order that the present invention may be more readily understood, an embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a tool forming part of the prior art;

Figure 2 is another tool forming part of the prior art;

Figure 3 is a perspective view of a tool comprising a flexible duct of the present invention;

Figure 4 is a perspective view of the flexible duct of the present invention;

Figure 5 is an exploded view of the flexible duct of the present invention, with an insert showing the details of the frame;

Figure 6 is a top view of the tool of Figure 3; and

Figure 7 is a plan view of the tool of Figure 3. Figure 3 shows a tool 1 comprising a first conduit 2, a second conduit 3, a first connector 4 and a second connector 5. The first conduit 2 has a narrower profile than the second conduit 3, and the second conduit 3 surrounds the first conduit 2 such that the first conduit 2 slides in and out of the second conduit 3, allowing for extension of the tool 1. When the tool 1 is extended, the first conduit 2 is revealed from the second conduit 3. Such a tool 1 can be said to be telescopic.

The first conduit 2 is connected at one end to the second conduit 3 and at the opposite end to the first connector 4. The second conduit 3 is connected to the second connector 5. The second connecter 5 is located at the end opposite to where the first conduit 2 connects to the second conduit 3. The first connector 4 can be used for connecting a nozzle or cleaner head to the end of the tool 1. Alternatively, the first connector 4 can act as an inlet for the tool without the need for a nozzle or cleaner head attachment. The second connector 5 is used to connect the tool 1 to a wand or hose that further connects to a vacuum cleaner.

The tool 1 further comprises locking means 6 for locking the conduits 2,3 of the tool 1 out at maximum extension (as shown in Figure 3) and also for locking the first conduit 2 in a retracted position when it is located within the second conduit 3.

The first conduit 2 comprises a flexible portion or duct 7 and rigid portions 8 at either end of the flexible duct 7. The flexible duct 7 is shown in more detail in Figures 4 to 7 and comprises a helical frame 9 and a helical strip 10. The flexible duct 7 has a generally rectangular shape cross section, with two longer side surfaces 11,12 (best shown in Figure 6) and two shorter top and bottom surfaces 13,14 (best shown in Figure 7). The flexible duct 7 can flex in directions normal to the helical axis 15. For example, the flexible duct 7 is free to flex in a left to right direction, and also in an up and down direction, as shown in Figures 6 and 7 respectively. Dashed lines are used to illustrate the general degree of movement of the flexible duct 7 in directions normal to the helical axis 15. The helical frame 9 is formed of a single piece of rigid material and comprises a plurality of loops 16 that are arranged around the helical axis 15. The loops 16 are spaced at regular intervals along the helical axis 15 with a space between each loop 16. The profile of each loop 16 is shown in more detail in Figure 5. Each loop 16 comprises a central band 17 flanked by wings 18,19 on either side of the band 17, the band 17 being of greater thickness than the wings 18,19. That is to say that the height of the wings 18,19 is less than the height of the central band 17 in a direction normal to the helical axis 15. Each wing 18,19 extends all the way around the central band 17 in a direction parallel with the helical axis 15 and is provided with anchors 20 which are used as keying features during the manufacturing process of the tool 1. One wing 19 is provided with two projections 21 that extend towards an adjacent loop 16. The projections 21 extend in a direction that is parallel to the helical axis 15. The projections 21 are positioned on the top and bottom of the wing 19 (best shown in Figure 5). The projections 21 act to restrict the movement of the flexible portion 7 in the up and down direction relative to the movement of the flexible portion 7 in the left to right direction.

The helical strip 10 is formed of a single piece of a pliable material in the form of a tape, bandage or ribbon. The helical strip 10 extends along the helical axis 15 and around part of the helical frame 9. Specifically, the helical strip 10 is either overmoulded onto or bonded to the helical frame 9 such that the strip 10 fills the space between each of the loops 16, providing a continuous coupling between the loops 16 of the frame. The helical strip 10 seals the spaces in the helical frame 9 to provide a duct for fluid to be drawn through. Furthermore, the helical strip 10 is provided between the loops 16 only on the wings 18,19, such that the exterior of the helical strip 10 is flush with the exterior of the central band 17. As shown in Figure 4, the central band 17 of each loop 16 is exposed along the length of the duct 7. Since the helical strip 10 is provided in the space between the loops 16 and flush with the loops 16 the overall exterior profile of the flexible duct 7 is reduced.

The helical strip 10 is able to flex and stretch, allowing the flexible portion 7 to bend or twist from a straight position and return back to its original shape. The helical strip 10 has indents 22 provided on the side surfaces 11,12 of the duct 7. The indents 22 improve the flexibility of the duct 7 in two ways. Firstly, the indents 22 reduce the stiffness of the helical strip 10 on a side surface 11,12 that lengthens during a flexing movement (that is to say, the side surface 11,12 on the outside of the bend of the flexible duct portion 7). Secondly, the indents 22 allow for the material of the helical strip 10 to crease and fold more readily on a side surface 11,12 that contracts during a flexing movement (that is to say, on the side surface 11,12 on the inside of the bend of the flexible duct portion 7).

The anchors 20 provided on the wings 18,19 of each loop 16 of the frame 9 act as keying features as the strip 10 is overmoulded onto the frame 9. During manufacture, the pliable material flows over the wings 18,19 and into or onto the anchors 20. The anchors 20 are holes that are shaped so that the helical strip 10 is secured onto the frame 9 once the pliable material has cured. The pliable material is only provided on the wings 18,19 such that, once cured, the exterior surface of the helical strip 10 is flush with the exterior of the central band 17. In addition, a mould insert can be placed inside the flexible portion 7 of the first conduit 2 and against the inside surface of the loops 16 such that the pliable material flows and cures against the mould insert. The mould insert is then removed after curing to leave behind a smooth interior surface of the duct 7 as the helical strip 10 is cured flush with the interior profile of the loops 16.

During use, the tool 1 is extended so that the first conduit 2 is exposed as it slides outs of the second conduit 3. The travel of the first conduit 2 is locked when the tool 1 is in an extended position (as shown in Figure 3). The profile of the tool 1 is such that at least the first conduit 2 can be placed into a gap or crevice. The user can manoeuvre the tool 1 by holding either the second conduit 3, or by holding an extension wand or handle connected via the second connector 5.

As the tool 1 is manoeuvred into a crevice, the flexible duct 7 of the first conduit 2 can bend or flex against the walls or floor of the crevice. The user will naturally force the tool 1 against the surface/floor of the crevice to be cleaned. As the force is applied, the flexible duct 7 will flex in an up/down and/or left/right direction. As the duct 7 bends or flexes in the up down direction, the projections 21 limit the range of movement of the helical frame 9. This improves the control of the tool 1 and gives the user the ability to steer the tool 1 in a crevice without the duct 7 flexing in an unwanted direction (i.e. up/down direction). In addition, prevents the flexing of the duct 7 beyond a point where damage or kinking would occur. Thus, although the maximum range in movement in the up and down direction is decreased, the duct 7 is protected against folding or kinking, and also reinforced to prevent any damage to the tool 1.

The movement of the flexible duct 7 in the left and right direction is improved by the indents 21 that are provided on the side surfaces of the helical strip 10. In use, the indents 21 provide improved flexibility, in that they are able to stretch more easily than the rest of the helical strip 10 since less material is present. In addition, the indents 21 provide a crease or fold for the helical strip 10 to bend into when flexing the duct 7. Thus, the steering of the tool 1 in a left/right direction is easier relative to steering in an up/down direction.

Although the flexible duct 7 is shown as part of a tool 1 for a vacuum cleaner, it will be appreciated that such a duct could be used on other parts of the vacuum cleaner, such as a suitable replacement for a hose, or a tube, or a conduit connecting parts of a vacuum cleaner.