Roller for a floor cleaner

Abstract

A roller 10 for a floor cleaner configured to rotate about a central axis A-A, wherein the roller comprises an axially extending core 12 and at least one cleaning bar 18 that extends along the roller

Description

BACKGROUND Various types of floor cleaner are known. One example comprises a vacuum cleaner for removing dirt and debris from a dry floor. Another example comprises a wet floor cleaner for mopping wet floors (including applying cleaning liquid to an initially dry floor). Vacuum cleaners typically comprise a main body containing dirt and dust separating apparatus, a cleaner head connected to the main body and having an opening, and a motor-driven fan unit for drawing dirt-bearing air through the opening and the cleaner head, and into the main body. A driven agitator, usually in the form of a brush roller, may be rotatably mounted within a suction cavity of the cleaner head. Some wet floor cleaners comprise one or more rotating mop rollers which may be driven by a motor. The one or more mop rollers may be wetted by water or a floor cleaning solution. Both types of cleaner may feature a brush or mop roller cleaning arrangement to remove dirt and / or debris from the brush or mop roller. In the case of a wet floor cleaner, the roller cleaning arrangement may also remove liquid from the mop roller along with dirt and debris. It is against this background that the present invention has been devised. SUMMARY The examples of the invention provide a roller for a floor cleaner configured to rotate about a central axis, wherein the roller comprises an axially extending core; and at least one cleaning bar that extends along the roller along a helical path. The core extends between a first end and a second end and tapers between the first end and the second end. The at least one cleaning bar extends radially outwardly from the core to define a maximum outer diameter of the roller. The radial extent of the at least one cleaning bar varies along the length of the roller so that the maximum outer diameter along the length of the roller describes a cylindrical envelope when the roller rotates in use. In one example, the roller is a roller for a wet floor cleaner. The present invention is advantageous as the cylindrical outer envelope of the cleaning bar provides alignment between the outer edge of the cleaning bar and a surface to be cleaned. The cleaning bar facilitates collection of debris from said surface, in particular elongate debris such as hair and other long fibres which are collected on the core of the roller as the roller rotates. The tapered core facilitates migration of elongate debris along the roller in the direction of the taper (i.e. towards the smaller end of the core) so that it can be collected together in one area for removal. The surface may be the surface of a floor cleaning roller located adjacent the roller. In one example, a first portion of the core tapers from the first end towards the second end. In other words, the diameter of the core varies along its length from a maximum at the first end to a minimum at or towards the second end. Generally, the taper is of a constant gradient. The core may be frustoconical in shape. During the use of the roller, debris which has become wrapped around the roller tends to migrate along the roller towards the smaller or tapered end where it may be more easily removed from the roller as a concentrated collection of debris. In another example, the first portion of the core tapers from the first end towards a relatively narrow part of the core located between the first end and the second end, and a second portion of the core tapers from the second end towards the relatively narrow part of the core. In other words, the diameter of the core varies along the length from a relatively larger diameter at both the first end and the second end to a relatively smaller diameter located between the first and second ends. Generally, the taper is of a constant gradient. The relatively narrow part of the core may be at or around the mid-point of the core. However, this is not essential, and the narrowest part of the core can be at any position between the first and second ends of the core. In one embodiment, the diameter of the core at the first end and the second end is the same. The core may be shaped like an hour glass. During use of the roller according to this example, debris which has become wrapped around the roller tends to migrate along the roller from both the first end and the second end towards the relatively narrow part of the core where it may be more easily removed from the roller as a concentrated collection of debris. Concentration of the debris at the relatively narrow part of the core may make access to, and removal of, the debris easier. In an alternative example, a first portion of the core may taper from a relatively wide part of the core located between the first end and the second end towards the first end, and a second portion of the core may taper from the relatively wide part of the core towards the second end. In this embodiment, the core of the roller has a maximum diameter located between the first end and the second end which may be at or around the mid-point. However, this is not essential, and the widest part of the core can be located at any position between the first end and the second end of the core. During use of the roller according to this alternative example, debris which has become wrapped around the roller tends to migrate along the roller towards the first and the second ends, where it may be more easily removed from the roller and cleaner head as concentrated collections of debris. Optionally, the handedness of the helix of the at least one cleaning bar within the first portion of the core may be opposite to the handedness of the helix of the at least one cleaning bar within the second portion of the core. Providing a roller with opposite handed helices in the portions of the core having opposite directions of taper is beneficial where it is desirable for the effect of the helices of the cleaning bar(s) on debris wrapped around the core to be opposite for each portion of the core. In particular, it may be desirable for the helices of the cleaning bars to encourage debris to migrate in the direction of the taper. Where the roller has a taper towards the first and / or second end of the core, a removable bobbin may be positioned adjacent one or both of the first end and the second end of the core. The bobbin may be removed to facilitate cleaning of and removal of debris from the roller. Alternatively, the first and / or second end of the core may be free so that debris may fall off the end. In this case the roller may be supported from one end or from a point between the first and second ends. Where the roller has a taper towards a relatively narrow part of the core located between the first and second ends, a removable bobbin may be positioned proximate the relatively narrow part of the core. The bobbin may be removed to facilitate cleaning of and removal of debris from the roller. Alternatively, if no bobbin is used, the roller may have a split core providing first and second core portions that are configured to be separable to facilitate debris removal. This provides a user easy access to each of the core portions for cleaning of and removal of debris from the core of the roller. In a further alternative, the roller may comprise two separate roller portions - each having a tapered core - which face one another and which are cantilevered from their non-adjacent ends to leave a gap between them so that debris may fall off the separate roller portions. In one example, a radially outermost portion of the at least one cleaning bar comprises a pattern of teeth. Such teeth assist in the collection of debris from a surface as the roller is moved across said surface. The teeth also provide a form of agitation against the surface enhancing debris removal. The pattern of teeth may be a pattern of asymmetric teeth. The pattern of teeth may comprise a plurality of teeth arranged successively along the at least one cleaning bar, wherein at least one tooth at least partially overlaps an adjacent tooth in the direction of the central axis. That is to say, when viewed from the side looking towards the axis of rotation, successive teeth overlap one another in the axial direction. This is beneficial as the number of points of agitation against a surface are increased to improve debris collection. In one example, the pattern of teeth may comprise generally “V” shaped notches defined between adjacent teeth, wherein the internal angle of each “V” shaped notch may be less than or equal to 90 degrees. The tooth formation resulting from such notches facilitates the snagging and collection of elongate debris from the surface to be cleaned. Optionally a base of each “V” shaped notch may be located on a radial line connecting the central axis to a radially outer peak of one of the teeth defining said “V” shaped notch. This helps to prevent debris from becoming stuck or wedged within the notches. In one example, a circumferential extent of each tooth is greater than a radial extent of each tooth to facilitate migration of debris along the roller. Each tooth may comprise a first surface which extends predominantly in a radial direction (where the radial direction is a direction which passes through and is perpendicular to the axis of rotation), and a second surface which extends predominantly in a circumferential direction (where the circumferential direction is a direction which is tangential to a circle centred on the axis of rotation). Such a configuration assists in collecting debris onto the roller, and assists in migration of the debris along the roller. The second surface of each tooth may be at least partially curved to facilitate migration of debris along the roller by preventing or reducing snagging of debris. The cleaning bar may comprise a flexible material to facilitate debris pickup. The roller may be formed from a flexible non-porous material. This is beneficial as the flexible non-porous material facilitates roller cleaning and sanitation. The roller may comprise a pair of cleaning bars which extend along the roller in the same helical direction and which are spaced equidistant from one another. This facilitates efficient migration of debris along the roller. Alternatively, the roller may comprise three or more cleaning bars which extend along the roller in the same helical direction and which are spaced equidistant from one another. In another aspect the present invention provides a cleaner head for a floor cleaner comprising: a roller according to any preceding claim; and a drive arrangement configured to rotate the roller about the central axis. Optionally, the drive arrangement may be configured to rotate the roller in a roller clearing direction in which for a portion of the core having a cleaning bar describing a lefthanded helix the vector of rotation is equal to the direction of the taper, and / or for a portion of the core having a cleaning bar describing a righthanded helix the vector of rotation is opposite to the direction of the taper. Rotation of the roller in this way facilitates migration of hair or other fibres along the roller in the direction of the taper as the cleaning bar(s) act in the manner of an Archimedes screw. For this reason, the described direction of rotation is named the roller clearing direction. However, hair and other fibres will still tend to migrate along the roller in the direction of the taper even when the roller is rotated in the opposite direction. The drive arrangement may optionally be configured to rotate the roller in a debris pickup direction which is opposite to the roller clearing direction. This advantageously provides for two distinct modes of operation, one in which elongate debris is picked up from a surface but not assisted by the helix of the cleaning bar(s) to migrate in the direction of the taper (albeit that some migration will occur due to the taper itself), and one in which elongate debris is assisted by the helix of the cleaning bar(s) to migrate in the direction of the taper. This is beneficial if it is desirable to remove debris from the roller at a specific time or locations (such as in a cleaner docking station). In one example, for a cleaner head comprising a roller having cleaning bars(s) with a pattern of teeth, where each tooth comprises a first surface which extends predominantly in the radial direction and a second surface which extends predominantly in the circumferential direction, the drive arrangement is configured to rotate the roller so that the first surface of each tooth precedes the second surface of each tooth in the direction of rotation. This arrangement encourages debris collection as the teeth hook elongate debris from the surface being cleaned. When the roller is rotated in the opposite direction, this arrangement facilitates release of the debris from the teeth. The cleaner head may comprise a floor cleaning, or primary roller, and a roller for cleaning the primary roller. The roller for cleaning the primary roller is referred to as a debris roller. In this example, the debris roller is located adjacent the primary roller and configured to clean debris from the primary roller in use. The primary roller may be a wet mop roller. BRIEF DESCRIPTION OF THE DRAWINGS Figures la, lb and 1c show side views of different tapered rollers; Figures 2a and 2b show an explanation of the handedness of helixes;' Figure 3 is a bottom view of a cleaner head in which the roller of Figure la is mounted; Figure 4 is a perspective view of a floor cleaner having a cleaner head in accordance with an example; Figures 5a, 5b and 5c show schematic isometric views of assemblies for a hard floor cleaner; Figures 6a and 6b show a side view and an enlarged side view of a roller respectively having a cleaner bar with a pattern of teeth; Figure 7a shows a side view of a tapered roller; Figure 7b shows a side view of the tapered toller of Figure 7a with the bobbin removed; Figures 8a to 8c show schematic views of hair loops wrapped around rollers having differing numbers of cleaning bars; Figure 9a shows a bottom view of a cleaner head having rollers showing debris pick-up; and Figure 9b shows a bottom view of the cleaner head of Figure 9a showing debris migration. DETAILED DESCRIPTION Figure la shows a side view of a roller 10 having a tapered core 12. In this example, the core 12 tapers from a relatively larger diameter at a first end 14 to a relatively smaller diameter at a second end 16. A cleaning bar 18 extends along the tapered core 12 along a helical path and describes an outer diameter 20 of the roller 10. As will be explained in greater detail below, the cleaning bar 18 has a lefthanded helix. The outer diameter 20 of the roller 10 is constant along the length of the roller 10; thus, the radial extent of the cleaning bar 18 varies along the length of the roller 10. In this example, the radial extent of the cleaning bar 18 increases from the first end 14 to the second end 16, i.e. the radial extent of the cleaning bar 18 increases as the core tapers. At the second end 16 of the core 12, a removable bobbin 22 is provided. The bobbin 22 is a push or snap fit component and is removed by pulling it away from the core 12. In alternative embodiments, the bobbin 22 may be a screw fit component. Figure lb shows a side view of a roller 10’ having a tapered core 12. In this example, a first portion 13a of the core 12 tapers from a relatively larger diameter at a first end 34 to a relatively smaller diameter at a mid-point 38 of the core 12, and a second portion 13b of the core 12 tapers from a relatively larger diameter at a second end 36 to the relatively smaller diameter at a mid-point 38. A pair of cleaning bars 18a, 18b extend along the first portion 13a of the core 12. The cleaning bars 18a, 18b extend in the same helical direction as one another and are spaced equidistant from one another. Similarly, a pair of cleaning bars 18c, 18d extend along the second portion 13b of the core 12. The cleaning bars 18c, 18c extend in the same helical direction as one another and are spaced equidistant from one another. As will be explained in greater detail below, the cleaning bars 18a, 18b comprise a righthanded helix, whereas the cleaning bars 18c, 18d comprise a lefthanded helix. The cleaning bare 18a-18d describe an outer diameter 20 of the roller 10’. The outer diameter 20 of the roller 10’ is constant along the length of the roller 10’; thus, the radial extent of the cleaning bars 18a-18d varies along the length of the roller 10’. In this example, the radial extent of the cleaning bars 18a-18d increases from the first end 34 and the second end 36 towards the mid-point 38 as the core tapers. Although not shown in Figure lb, the roller 10’ may comprise a removable bobbin located between the first 13a and second 13b portions of the roller 10’. Such a bobbin is described below with reference to Figure 4b. In an alternative example, the core 12 may be a split core which is separable to allow the two halves of the core 12 to be separated to facilitate removal of elongate debris which has collected towards the mid-point in use (described further below). Figure 1c shows a side view of a roller 10” having a tapered core 12. In this example, a first portion 13a of the core 12 tapers from a relatively larger diameter at a mid-point 48 of the core 12 to a relatively smaller diameter at a first end 44, and a second portion 13b of the core 12 tapers from the relatively larger diameter at the mid-point 48 to a relatively smaller diameter at a second end 46. A pair of cleaning bars 18a, 18b extend along the first portion 13a of the core 12. The cleaning bars 18a, 18b extend in the same helical direction as one another and are spaced equidistant from one another. Similarly, a pair of cleaning bars 18c, 18d extend along the second portion 13b of the core 12. The cleaning bars 18c, 18c extend in the same helical direction as one another and are spaced equidistant from one another. As will be explained in greater detail below, the cleaning bars 18a, 18b comprise a lefthanded helix, whereas the cleaning bars 18c, 18d comprise a righthanded helix. The cleaning bars 18a-18d describe an outer diameter 20 of the roller 10”. The outer diameter 20 of the roller 10” is constant along the length of the roller 10”; thus, the radial extent of the cleaning bars 18a-18d varies along the length of the roller 10”. In this example, the radial extent of the cleaning bars 18a-18d increases from the mid-point 48 towards the first end 44 and the second end 46 as the core tapers. At the first end 44 and the second end 46 of the core 12, removable bobbins 52 are provided. The bobbins 52 are push or snap fit components and are removed by pulling away from the core 12. In alternative embodiments, the bobbins 52 may be a screw fit component. Each of the rollers 10, 10’, 10” have a central axis A-A and describe a cylindrical envelope when the roller rotates, in use. The roller 10,10’, 10” may be used in a wet floor cleaner or in a vacuum cleaner. The handedness of the helical cleaning bars 18 is explained with reference to Figures 2a and 2b. Figure 2a shows a portion of a core 12 with a cleaning bar 18 which describes a lefthanded helix. This can be ascertained by viewing the roller with its central axis A-A in a vertical orientation (as shown). For a left handed helix, the visible part of each turn of the helix appears to extend in an upward direction from right to left as indicated by arrow T. Figure 2b shows a portion of a core 12 with a cleaning bar 18 which describes a righthanded helix. Again, this can be ascertained by viewing the roller with its central axis A-A in a vertical orientation (as shown). For a right handed helix, the visible part of each turn of the helix appears to extend in an upward direction from left to right as indicated by arrow T. Figure 3 shows an example of the roller 10 of Figure la mounted for rotation in a cleaner head 100 of a vacuum cleaner. The cleaner head 100 comprises a housing 114 and a sole plate 116 connected to the housing 114. In use, the sole plate 116 is placed upon the floor surface to be cleaned. The sole plate 116 comprises a leading section 121 and a trailing section 120 located on opposite sides of a suction opening 122 through which an airflow is drawn into the cleaner head 100. The suction opening 122 is generally rectangular in shape, and is delimited by a front working edge 124, a rear working edge 126, a first side edge 128 and a second side edge 130 which is parallel to the first side edge 128. The front working edge 124 is defined by the intersection of the leading section 121 of the sole plate 116 with the housing 114, and the rear working edge 126 is defined by the intersection of the trailing section 120 of the sole plate 116 with the housing 114. The suction opening 122 houses the roller 10 for agitating a floor surface to be cleaned and for collecting elongate debris such as hair and other long fibres from the floor. The roller 10 is rotatable relative to the housing 114 about an axis which is collinear with the longitudinal axis A of the roller 10. As described above, the roller 10 comprises a core 12 and a helical cleaning bar 18. The cone angle of the core 12, that is, the angle subtended between the longitudinal axis of the core 12 and external surface of the core 12, is preferably in the range from 5 to 15°, and in this embodiment is approximately 7°. The cleaning bar 18 is upstanding from the external surface of the core 12, and extends helically along the external surface of the core 12 from the second end 14 to the first end 16 thereof. The cleaning bar 18 forms a lefthanded helix. The cleaning bar 18 extends substantially the entire length of the core 12 and protrudes outwardly beyond the sole plate 116 to contact the floor surface as the cleaner head 100 is manoeuvred over the surface. In this example, the roller 10 is supported for rotation at the first end 14 and is unsupported at the second end 16. The roller 10 is therefore cantilevered from the first end 14. The bobbin 22 shown in Figure la is therefore not required (but may be used if desired). In use, when the cleaner head 100 is operated in a debris pickup mode, the roller 10 is rotated in a debris pickup direction which is counter-clockwise as viewed from the second end 14 of the roller 10 (as depicted by arrow X in Figure 3). Using the standard right hand vector of rotation rule, the debris pickup direction of rotation can be described by a vector Y which is aligned with the central axis of rotation A of the roller 10 and which has a direction opposite to the direction of taper of the core 12. When the cleaner head 100 is operated in the debris pickup mode, a portion of the cleaning bar 18 contacts the floor surface to be cleaned and collects debris from the floor surface which is removed to a debris bin by suction. However, elongate fibres such as hair or other long fibres tend to become wrapped around the core 12 of the roller 10 and so cannot be removed to the bin. After a set period of time, or after the debris pickup has been completed, the cleaner head 100 is operated in a roller clearing mode in which the roller 10 is rotated in a roller clearing direction which is opposite to the debris pickup direction X. In this mode of operation, elongate debris which has become wrapped around the core 12 tends to migrate towards the unsupported tapered end 16 of the roller 10 as the roller 10 rotates in the roller clearing direction. Once at the unsupported tapered end 16 of the roller 10, the concentrated ball of hair and other long fibres can fall off to be collected by the cleaner head 100 when being operated in the debris pickup mode once again. In an alternative mode of operation, the roller 10 may be rotated in the roller clearing direction at all times. For example, this may be a desirable mode of operation if the cleaning bar 18 has a smooth and / or flexible outermost edge. Figure 4 shows a vacuum cleaner 200 which could be used with the cleaner head 100 described with respect to Figure 3. The vacuum cleaner 200 includes a main body 202 having a cleaner head 100 attached at its lower end. The cleaner head 100 is shown in schematic form in Figure 4 but could be as described with respect to Figure 3 or any other embodiment of the invention described herein. As shown, the main body 202 comprises bin and suction assembly 204 and an elongated handle 207 that extends upwardly from the cleaner head 100 so it can be manoeuvred from a standing position. A cleaner head having a construction such as that described above in respect of Figure 3 can also be used with wet floor cleaner. In this example, the cleaner head is adapted to clean dirt and moisture from a floor surface. The rollers 10, 10’, 10” described above can be used within wet or dry cleaner heads. It has been found in practice that rollers for dry floor cleaners (such as vacuum cleaners) perform best with cone angles of between 5 degrees and 15 degrees. However, larger cone angles may be used (particularly for larger floor cleaners). For wet floor cleaners the rollers perform best with cone angles from 2 degrees to 20 degrees. Cone angles of 3 degrees to 4 degrees have been found to work well for wet floor cleaners. In another example, one or more rollers may be used for the removal of debris from another roller within the cleaner head. This is useful as debris picked up by a surface contacting, or primary roller, can be removed from the surface of the primary roller by the second, or debris, roller, leaving the primary roller relatively free of debris. It is particularly useful to remove elongate debris such as hair or other long fibres from the primary roller as such elongate debris can become wrapped around the primary roller thereby decreasing its cleaning efficiency. Figure 5a shows a schematic isometric view of an assembly 150 for a floor cleaner. The assembly 150 comprises a primary roller 152 and a debris roller 10 having a tapered core 12 such as was described with respect to Figure la. The primary roller 152 is mounted for rotation about an axis B-B, and the debris roller 10 is mounted for rotation about an axis C-C. The primary roller 152 and the debris roller 10 are supported for rotation within a housing (not shown). The primary roller 152 is arranged so that, in use, during cleaning of a floor surface 157, the lowermost portion of the primary roller 152 contacts the floor surface 157. The debris roller 10 does not contact the floor surface 157. The debris roller 10 is arranged with respect to the primary roller 152 such that the axis of rotation C-C of the debris roller 10 is parallel to the axis of rotation B-B of the primary roller 152. As described with respect to Figure la, the debris roller 10 has a cleaning bar 18 which extends radially out from the core 12. The radial extent of the cleaning bar 18 increases from the first end 14 so that the radial extent of the cleaning bar 18 increases as the core 12 tapers to maintain a constant outer diameter of the debris roller 10 along its’ length. Thus, the outermost edge of the cleaning bar 10 contacts a portion 154 of the external surface 155 of the primary roller 152 along the axial length L of the primary roller 152. The cleaning bar 18 forms a lefthanded helix. In use, when a floor cleaner comprising the assembly 150 is operated in a debris pickup mode, the primary roller 152 is rotated to clean the floor surface 157. If the cleaner is a wet floor cleaner, the primary roller 152 may be a mopping roller which may be wetted by a wetting apparatus (not shown) located in the cleaner head of the cleaner. As the floor cleaner is moved over the floor surface 157, debris such as dust, grit, hair and other long fibres are picked up by the primary roller 152. In the debris pickup mode, the debris roller 10 is rotated in a first, or debris pickup, direction which is clockwise as viewed from the second end 16 of the debris roller 10. Using the standard right hand vector of rotation rule, the debris pickup direction of rotation can be described by a vector Y which is aligned with the central axis of rotation C-C of the debris roller 10 and which has a direction opposite to the direction of taper (or migration direction) of the core 12. The cleaning bar 18 contacts the primary roller 152 and collects debris from the primary roller 152. Any elongate fibres such as hair or other long fibres collected from the primary roller 152 then become wrapped around the core 12 of the debris roller 10. After a set period of time, or after the debris pickup has been completed, the assembly 150 is operated in a debris roller clearing mode in which the debris roller 10 is rotated in a second, or roller clearing, direction which is opposite to the debris pickup direction. In this mode of operation, elongate debris which has become wrapped around the core 12 tends to migrate towards the tapered end 16 of the debris roller 10 as the debris roller 10 rotates in the roller clearing direction. Once at the tapered end 16 of the debris roller 10, the concentrated ball of hair and other elongate fibres may be removed from the debris roller 10. The primary roller 152 is also rotated in this mode of operation. The primary roller 152 may rotate in either direction when operating in the in the debris pickup mode or in the debris roller clearing mode. However, the primary roller typically rotates in the same direction as the debris roller. Figure 5b shows a schematic isometric view of an alternative assembly 170 for a floor cleaner. The assembly 170 is the same in all respects, and operates in the same way as the assembly 150 described above except in that assembly 170 comprises a debris roller 10’ having a tapered core 12, as described with respect to Figure lb. The core 12 of the debris roller 10’ has a shape which tapers from the first end 34 of the debris roller 10’ and from the second end 36 of the debris roller 10’ to a relatively smaller diameter at a mid-point 38 of the core 12. As described above, cleaning bars 18a-18d extend along the tapered core 12 along a helical path and defines a maximum outer diameter 20 of the debris roller 10’. The radial extent of the cleaning bars 18a-18d varies along the length of the debris roller 10’ so that the maximum outer diameter 20 of the debris roller 10’ is constant along the length of the roller 10’. The debris roller 10’ has a first core portion 13a which tapers from the first end 34 towards the mid-point 38, and a second core portion 13b which tapers from the second end 36 towards the mid-point 38. Advantageously, the debris roller 10’ may be split at the midpoint 38 to enable removal of debris from the debris roller 10’. The first core portion 13a and the second core portion 13b may be connected at the mid-point by a bobbin 176 removably attached to one or both of the first core portions 13a and second core portions 13b to facilitate removal of debris from the roller 10’. In another embodiment, one or both of the first portion 13a and the second portion 13b may be cantilevered from the outermost ends 14, 16 using a pivotable mounting arrangement (not shown). This arrangement facilitates removal of debris from the debris rollers. In another embodiment, additional debris rollers may be utilised, each may be supported at the outermost end and cantilevered away from a support for cleaning of the primary roller and debris removal. The cleaning bars 18a, 18b located in the first portion 13a of the debris roller 10’ describe a righthanded helix, and the cleaning bars 18c, 18d located in the second portion 13b of the debris roller 10’ describe a lefthanded helix. When the assembly 170 is operated in the debris pickup mode, the debris roller 10’ is rotated in a debris pickup direction which is counter-clockwise as viewed from the second end 36 of the debris roller 10’. Using the standard right hand vector of rotation rule, the debris pickup direction of rotation can be described by a vector Y which is aligned with the central axis of rotation of the debris roller 10’ and which has a direction opposite to the direction of taper of the second portion 13b of the core 12. In the pick-up mode, the cleaning bars 18a-18d contact the primary roller 152 and collects debris from the primary roller 152. Any elongate fibres such as hair or other long fibres collected from the primary roller 152 then become wrapped around the core 12 of the roller 10’. After a set period of time, or after the debris pickup has been completed, the assembly 170 is operated in a debris roller clearing mode in which the debris roller 10’ is rotated in a roller clearing direction which is opposite to the debris pickup direction. In this mode of operation, elongate debris which has become wrapped around the core 12 tends to migrate towards the mid-point 38 of the debris roller 10’ as the debris roller 10’ rotates in the roller clearing direction. Once at the mid-point 38 of the debris roller 10’, the concentrated ball of hair and other elongate fibres may be removed from the debris roller 10’ by pulling or cutting the ball of fibres, or by separating the debris roller 10’ at a split point or bobbin located at the mid-point 38. Alternatively, if the first and second portions 13a, 13b are cantilevered, the ball of fibres may fall off the debris roller 10’. The primary roller 152 is also rotated in this mode of operation. The primary roller 152 may rotate in either direction when operating in the debris pickup mode or in the roller clearing mode. However, the primary roller typically rotates in the same direction as the debris roller. Figure 5c shows a schematic isometric view of another alternative assembly 180 for a floor cleaner. The assembly 180 is the same in all respects, and operates in the same way as the assembly 150 described above except in that assembly 180 comprises roller 10” having a tapered core 12, as described with respect to Figure 1c. The debris roller 10” has a shape which tapers from a relatively larger diameter at a mid-point 48 of the core 12 towards a relatively smaller diameter at both first end 44 and second end 46 of the debris roller 10”. Cleaning bars 18a-18d extend along the tapered core 12 along a helical path and describes a maximum outer diameter 20 of the debris roller 10”. The radial extent of the cleaning bars 18a-18d varies along the length of the debris roller 10” so that the maximum outer diameter 20 of the debris roller 10” is constant along the length of the debris roller 10”. In this embodiment, the debris roller 10” can be considered to comprise a first core portion 13a which tapers from the mid-point 48 towards the first end 44, and a second core portion 13b which tapers from the mid-point 48 towards the second end 46. Advantageously, the debris roller 10” may comprise a removable bobbin (not shown) at one or both of the first end 44 and second end 46 to facilitate debris removal from the debris roller 10”. The cleaning bars 18a, 18b located in the first portion 13a of the debris roller 10” describe a lefthanded helix, and the cleaning bars 18c, 18d located in the second portion 184 of the debris roller 10” describe a righthanded helix. When the assembly 180 is operated in the debris pickup mode, the debris roller 10” is rotated in a debris pickup direction which is counter-clockwise as viewed from the second end 46 of the debris roller 10”. Using the standard right hand vector of rotation rule, the debris pickup direction of rotation can be described by a vector Y which is aligned with the central axis of rotation of the debris roller 10” and which has a direction equal to the direction of taper of the second portion 13b of the core 12. In the pick-up mode, the cleaning bars 18a-18d contact the primary roller 152 and collect debris from the primary roller 152. Any elongate fibres such as hair or other long fibres collected from the primary roller 152 then become wrapped around the core 12 of the roller 10”. After a set period of time, or after the debris pickup has been completed, the assembly 180 is operated in a debris roller clearing mode in which the debris roller 10” is rotated in a roller clearing direction which is opposite to the debris pickup direction. In this mode of operation, elongate debris which has become wrapped around the core 12 tends to migrate towards the ends 44,46 of the debris roller 10” as the debris roller 10” rotates in the roller clearing direction. Once at the ends 44, 46 of the debris roller 10”, the concentrated balls of hair and other elongate fibres may be removed from the debris roller 10” by pulling or cutting the ball of fibres, or by separating the debris roller 10” from bobbins located at the ends 44, 46. The primary roller 152 may rotate in either direction when operating in the in the debris pickup mode or in the roller clearing mode. However, the primary roller typically rotates in the same direction as the debris roller. It the description of Figures 5a to 5c above there are two modes of operation, a debris pickup mode in which the debris roller rotates in a debris pickup direction, and a debris roller clearing mode in which the debris roller rotates in a roller clearing direction. It will be understood that in an alternative example the debris roller may be rotated in the respective roller clearing direction at all times. In one example, the debris roller 10, 10’, 10” and the primary roller 152 may be rotated by a common motor. Alternatively, the debris roller 10, 10’, 10” and the primary roller 152 may each be driven by its own separate motor. In the case of cantilevered debris rollers, each debris roller may be driven by its own separate motor, or may be driven by a common motor (which may or may not also drive the primary roller). In an alternative example, the roller 10, 10’, 10” and / or the primary roller 152 may be arranged, via gears for example, to rotate as the floor cleaner is pushed along the floor surface to be cleaned by a user. The primary roller 152 may comprise fabric covered roller, such as a microfibre covered roller, or a foam covered roller. The assembly 150, 170, 180 is located within a housing (not shown) and attached to a handle as is well known in the art; an example is shown in Figure 3. The cleaning bar(s) 18 are formed from a material which is rigid enough to be upstanding from the core 12 of the debris roller and engage with a surface to be cleaned (a floor or the surface of an adjacent roller). In one example, the cleaning bar 18 is formed from a resilient flexible material which may have a high coefficient of friction to facilitate collection of debris from the surface (floor or adjacent roller). The cleaning bar(s) 18 may comprise a smooth outermost edge for engaging the floor or roller surface. In other embodiments, the cleaning bar(s) 18 comprise a pattern of teeth. Referring now to Figures 6a and 6b which show a side view and an enlarged side view of a roller 210 respectively having a pattern of teeth 212 formed along and within the radially outer edge of the cleaning bar 18. In this example, the pattern of teeth 212 is successive along the cleaning bar 18 such that one tooth 211 immediately follows another. Each tooth 211 has a first surface 216 and a second surface 218 which form a notch 220 in the radial outer surface of the cleaning bar 18 between each adjacent tooth 211. The notches 220 are generally “V” shaped. As shown, in this example, the internal angle 0 of each notch 220 is less than 90 degrees at the point where the first 216 and second 218 surfaces meet. A base 222 of each “V” shaped notch is located on a radial line 224 connecting the central axis of the roller 210 to a radially outer peak 225 of an adjacent tooth 211. As best shown in Figures 7a and 7b, there is an overlap between successive teeth in the axial direction of the roller such that as the roller rotates in use, at least part of the second surface 218 of one tooth will contact the same part of the surface to be cleaned (floor or roller) as the immediately following tooth. Each of the teeth 211 has a circumferential extent which is greater than the radial extent. In other words, each tooth comprises a first surface 216 which extends predominantly in the radial direction, and a second surface 218 which extends predominantly in the circumferential direction; and the second surface 218 is longer than the first surface 216. The second surface 218 of each tooth is curved. However, in an alternative example the second surface 218 of the teeth 212 may be at least partially straight. The pattern of teeth 212 is configured so that when the roller 210 is rotated in the debris pickup direction in a debris pickup mode, the first surface 216 of the teeth precede the second surface 218 of the teeth in the direction of rotation. This assists in removing elongate debris from the floor or roller surface to be cleaned as such elongate debris may snag onto the teeth 211 and be pulled off the surface onto the roller 210. When the roller is operated in the roller clearing direction opposite to the debris pickup direction, the elongate debris which has been collected by the roller tends to slide along the second surface 218 of the teeth 211 as the roller 210 rotates in the roller clearing direction. The second surfaces 218 precede the first surfaces 216 when the roller rotates in the roller clearing direction and the teeth 212 no longer act to snag the debris. Figure 7a shows a portion of the roller 10 having a tapered core 12 and a cleaning bar 18. When the roller 10 is rotated in the debris pickup direction clockwise when viewed from the second end 16, the roller 10 picks up debris from a surface (a floor or another roller). The orientation of the teeth 211 on the cleaning bar 18 (with the first surfaces 216 preceding the second surfaces 218 in the direction of rotation) assist with the debris pickup as discussed above. When the roller 10 is rotated in the roller clearing direction - counterclockwise when viewed from the second end 16 - collected elongate debris tends to migrate towards the second end 16. If a removable bobbin 22 is provided at the second end 16, then as shown in Figure 7b the bobbin 22 can be removed, facilitating removal of the debris from the roller 10. The bobbin 22 can be subsequently replaced by aligning a press or snap fitting into the second end 16 of the roller 10. It will be appreciated that the bobbin 22 is not essential and that the debris may be removed by being pulled or cut from the roller 10, or may fall off if the roller 10 is cantilevered. The use of equally spaced helical cleaning bars, such as cleaning bars 18a-18d described above, has been found advantageous as it maximises the degree of taper of the core 12 of a roller. The largest diameter of the core 12 is constrained by the outer diameter of the cleaning bar(s) 18 as the diameter of the core 12 must be at least a little smaller than the outer diameter of the cleaning bar(s) 18 to permit the cleaning bar(s) 18 to interact with the opposing surface (floor or other roller). Figures 8a to 8c show schematic views of hair loops wrapped around rollers having differing numbers of cleaning bars. As shown in Figures 8a to 8c, the minimum diameter of the core 12a, 12b, 12c is constrained by an inscribed circle 400a, 400b, 400c formed when a hair loop 401a, 401b, 401c forms around the extremities of cleaning bars present. As examples, an elliptical hair loop 401a formed around two cleaning bars 18a, 18b (as shown in Figure 8a) inscribe a circle 400a, a rounded triangle hair loop 401b formed around three cleaning bars 18a, 18b, 18c (as shown in Figure 8b) inscribes a circle 400b of a greater diameter than the circle 400a, and a rounded square hair loop 401c formed around four cleaning bars 18a, 18b, 18c, 18d (as shown in Figure 8c) inscribe a circle 400c of a greater diameter than both circle 400a, 400b. If the core diameter 12a, 12b, 12c is smaller than the inscribed circle 400a, 400b, 400c of a hair loop 401a, 401b, 401c at a particular cross section, then the tapered surface will not interact with the hair loop which is detrimental to the migration of elongate debris (hair and other long fibres) in the direction of the taper (i.e. towards the smallest diameter) when the roller is rotated in the roller clearing direction. A larger degree of taper is advantageous as it enhances the elongate debris migration process. As can be seen from Figures 8a to 8c, the minimum diameter of the core 12a, 12b, 12c is significantly smaller for a two-bar arrangement (Fig. 8a) than for a three-bar or four-bar arrangement (Figs. 8b &8c). Figures 9a and 9b show an underside view of a cleaner head 300 for a wet floor cleaner. The cleaner head 300 has two primary rollers 152 and two debris rollers 10’ located within a housing 301. The debris rollers 10’ are each mounted adjacent a respective primary roller 152 and configured to rotate in a debris pickup direction to collect elongate debris 156 from the rollers 152, and to rotate in a roller clearing direction to facilitate migration of the collected elongate debris 156 towards the mid-point 38 of the respective debris rollers 10’. Advantageously, the cleaning bars 18 comprise a pattern of teeth 212 as previously described in relation to Figures 6a and 6b. The teeth 211 are orientated so that when the debris rollers 10’ rotate in their debris pickup direction, the first surface 216 of the teeth precede the second surface 218 of the teeth. This assists in the collection of debris 156 from the surface of the primary rollers 152 onto the debris rollers 10’. When the debris rollers 10’ are rotated in their roller clearing direction of rotation, the debris 156 is released from the teeth 211 and migrates along the debris rollers 10’ towards in the direction of the taper as previously discussed. In a further alternative example, a floor cleaner may comprise a roller having a core that has a constant diameter along its length. Such a roller may be used in a cleaner head such as that shown in Figure 3, or an assembly such as those shown in Figures 5a, 5b, 5c, 9a and 9b. In this example, the helical cleaning bar or bars of such a roller have a radial extent that is constant along the length of the core so the roller describes a constant outer diameter. The cleaning bar(s) may comprise a pattern of teeth 212 formed along and within the radially outer edge of the cleaning bar(s) as described above with respect to Figures 6a and 6b. The direction of rotation of the helical cleaning bar(s) of such a roller are as described above such that in a debris pickup direction of rotation the cleaning bar(s) collects elongate debris from the surface (floor or roller surface), and in a roller clearing direction of rotation collected elongate debris migrates along the roller as the roller rotates in the roller clearing direction. In a still further alternative example, a floor cleaner may comprise a roller having a tapered core and one or more cleaner bars that do not vary in radial extent along the length of the roller such that the maximum outer diameter of the roller varies along its length. In this case the roller must be mounted with its axis of rotation at an angle to the surface (floor or roller surface) to be cleaned so that the entire length of the cleaner bar(s) are able to contact said surface as the roller rotates. Such a roller may be used in a cleaner head such as that shown in Figure 3, or an assembly such as those shown in Figures 5a, 5b, 5c, 9a and 9b. The cleaning bar(s) may comprise a pattern of teeth 212 formed along and within the radially outer edge of the cleaning bar(s) as described above with respect to Figures 6a and 6b. The direction of rotation of the helical cleaning bar(s) of such a roller are as described above such that, in use, in a debris pickup direction of rotation, for a portion of the core having a cleaning bar describing a lefthanded helix the vector of rotation is opposite to the direction of the taper, and / or for a portion of the core having a cleaning bar describing a righthanded helix the vector of rotation is equal to the direction of the taper. The primary roller may be made from one of a number of types of material available, including but not limited to one of a number of compliant materials, generally absorbent materials, e.g. microfibre, foam (e.g. PVA, melamine). In each of the embodiments described above the roller(s) / debris roller(s) may be configured so that the cleaning bar(s) contact the surface to be cleaned when rotated in a roller clearing direction. Such contact may facilitate migration of debris by mechanical interaction of the debris with the surface to be cleaned. However, such contact is not 5 essential as the taper of the core, and / or the handedness of the helix with respect to the direction of rotation, is sufficient to facilitate migration of debris. The various rollers, assemblies, cleaner heads and cleaners described above may be used in any type of floor cleaner including user operated floor cleaners and robotic floor cleaners, 10 The various rollers, assemblies, cleaner heads and cleaners described above may be used in vacuum cleaners and / or wet floor cleaners which may be user operated or robotic.

Claims

1. A roller for a floor cleaner configured to rotate about a central axis, wherein the roller comprises:an axially extending core; andat least one cleaning bar that extends along the roller along a helical path,wherein the core extends between a first end and a second end and tapers between the first end and the second end, andwherein the at least one cleaning bar extends radially outwardly from the core to define a maximum outer diameter of the roller, wherein the radial extent of the at least one cleaning bar varies along the length of the roller so that the maximum outer diameter along the length of the roller describes a cylindrical envelope when the roller rotates in use.

2. A roller according to claim 1, wherein a first portion of the core tapers from the first end towards the second end.

3. A roller according to claim 2, wherein the first portion of the core tapers from the first end towards a relatively narrow part of the core located between the first end and the second end, and a second portion of the core tapers from the second end towards the relatively narrow part of the core.

4. A roller according to claim 1, wherein a first portion of the core tapers from a relatively wide part of the core located between the first end and the second end towards the first end, and a second portion of the core tapers from the relatively wide part of the core towards the second end.

5. A roller according to any claim 3 or 4, wherein the handedness of the helix of the at least one cleaning bar within the first portion of the core is opposite to the handedness of the helix of the at least one cleaning bar within the second portion of the core.

6. A roller according to claim 2, 4 or 5 when dependent on claim 4, comprising a removable bobbin positioned adjacent one or both of the first end and the second end of the core.

7. A roller according to claim 3, or 5 when dependent on claim 3, comprising a removable bobbin positioned proximate the relatively narrow part of the core.

8. A roller according to any preceding claim, comprising a split core providing first and second core portions that are configured to be separable to facilitate debris removal.

9. A roller according to any preceding claim, wherein a radially outermost portion of the at least one cleaning bar comprises a pattern of teeth.

10. A roller according to claim 9, wherein the pattern of teeth comprises a plurality of teeth arranged successively along the at least one cleaning bar, wherein at least one tooth at least partially overlaps an adjacent tooth in the direction of the central axis.

11. A roller according to any one of claims 9 or 10, comprising generally “V” shaped notches defined between adjacent teeth, wherein the internal angle of each “V” shaped notch is less than or equal to 90 degrees.

12. A roller according to claim 11, wherein a base of each “V” shaped notch is located on a radial line connecting the central axis to a radially outer peak of one of the teeth defining said “V” shaped notch.

13. A roller according to any one of claims 9 to 12, wherein a circumferential extent of each tooth is greater than a radial extent of each tooth.

14. A roller according to any one of claims 9 to 13, wherein each tooth comprises a first surface which extends predominantly in the radial direction, and a second surface which extends predominantly in the circumferential direction.

15. A roller according to claim 14, wherein the second surface of each tooth is at least partially curved.

16. A roller according to any preceding claim, wherein the cleaning bar comprises a flexible material.

17. A roller according to any preceding claim, formed from a flexible non-porous material.

18. A roller according to any preceding claim, comprising a pair of cleaning bars which extend along the roller in the same helical direction and which are spaced equidistant from one another.

19. A cleaner head for a floor cleaner comprising: a roller according to any preceding claim; and a drive arrangement configured to rotate the roller about the central axis.

20. A cleaner head according to claim 19, wherein the drive arrangement is configured to rotate the roller in a roller clearing direction in which for a portion of the core having a cleaning bar describing a lefthanded helix the vector of rotation is equal to the direction of the taper, and / or for a portion of the core having a cleaning bar describing a righthanded helix the vector of rotation is opposite to the direction of the taper.

21. A cleaner head according to claim 20, wherein the drive arrangement is configured rotate the roller in a debris pickup direction which is opposite to the roller clearing direction.

22. A cleaner head according to any one of claims 19, 20 or 21 when dependent on claim 14 or 15, wherein the drive arrangement is configured to rotate the roller so that the first surface of each tooth precedes the second surface of each tooth in the direction of rotation.

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