WO2021069860A1

WO2021069860A1 - Cleaner head for a vacuum cleaning appliance

Info

Publication number: WO2021069860A1
Application number: PCT/GB2020/052285
Authority: WO
Inventors: Stefan Koch
Original assignee: Dyson Technology Limited
Priority date: 2019-10-10
Filing date: 2020-09-22
Publication date: 2021-04-15
Also published as: GB2588157B; CN114466613B; CN114466613A; GB201914652D0; GB2588157A

Abstract

This invention relates to a cleaner head (10) for a vacuum cleaning appliance, the cleaner head (10) comprising a main body (12) supporting an elongate agitator bar (36). The elongate agitator bar (36) comprises a rotatable cylindrical body (42) having a first agitator formation (44) extending outwardly therefrom. The cylindrical body (42) defines a first channel (58) that extends along the cylindrical body (42) adjacent the first agitator formation (. The first channel (58) extends around the cylindrical body (42) helically and includes a first channel portion (62) extending around the cylindrical body (42) in a first helical direction and a second channel portion (64) extending around the cylindrical body (42) in a second helical direction that is counter to the first helical direction. The first and second channel portions (62), (64) meet to define an apex (66) of the first channel (58).

Description

CLEANER HEAD FOR A VACUUM CLEANING APPLIANCE

TECHNICAL FIELD

The invention relates generally to vacuum cleaners, and particularly to a cleaner head or floor tool which forms part of a vacuum cleaner. The invention is concerned specifically with rotationally- driven agitators used in such cleaner heads, whether or not the cleaner head is permanently or removably fixed on a respective vacuum cleaner. The type of vacuum cleaner is immaterial to the invention, and so the invention may relate to so-called bagged or bagless vacuum cleaners.

BACKGROUND

A vacuum cleaning appliance or, more simply, “vacuum cleaner”, typically comprises a main body, equipped with a suction source and a dust separator, and a cleaner head connected to the dust separator usually by a separable coupling. The cleaner head has a suction opening with which it engages a surface to be cleaned and through which dirt-laden air is drawn into the vacuum cleaner towards the dust separator. The cleaner head performs a crucial role in the effectiveness of a vacuum cleaner in removing dirt from a surface, whether that surface is a hard floor covering such as wood or stone, or a soft floor covering such as carpet. Therefore, much effort is made by vacuum cleaner manufacturers to optimise cleaner head design to improve performance.

Some cleaner heads are passive devices which rely on stationary elements such as so-called ‘active edges’ and bristle strips to dislodge dirt from floor coverings. These types of cleaner heads are relatively simple but generally their effectiveness at removing dirt from surfaces is limited. Often, they are recommended mainly for use on hard surfaces.

Conventionally, the most effective cleaner heads incorporate some kind of powered brush bar or agitator. Examples are known in which the agitator is driven by a turbine which is actuated by the air flow through the cleaner head. Other known arrangements involve the use of an electric motor that is arranged to drive the agitator. In these known arrangements, it is usual for the motor to be coupled to the agitator by a suitable drive linkage such as a belt or gear mechanism, although it is also known for the motor to be housed within the agitator which provides a particularly space- efficient arrangement.

In either example, the powered agitator serves to wipe and beat the floor surface in order to improve the capability of the cleaner head to remove dirt from the surface. A common configuration is for the agitator to carry an array of bristles that extend outwardly from the outer radial surface of the agitator. The bristles are typically relatively stiff so that they engage the floor surface aggressively as the agitator rotates, thereby serving as a means to scrape and strike the floor surface to loosen embedded particles. Other strips of material such as rubber and carbon fibre bristles or filaments may be used to provide complementary characteristics to the agitator. Byway of example, US8782851 B2 describes an agitator that may be provided with a combination of relatively stiff bristles, carbon filaments and rubber strips.

A significant design challenge is to optimise the way in which air flows through the cleaner head, from where air enters its interior, through the suction opening, to where air is discharged from an outlet towards the dust separator. It is known that air flow velocity is an important factor in pick up performance since dirt particles are transported more effectively when the velocity of air moving through the tool is high. However, maintaining a high flow velocity is not straightforward, and generally correlates to high energy consumption. This is generally undesirable due to the drive towards energy efficient machines, and has particular relevance to battery powered vacuum cleaners where energy efficiency has a direct effect on available runtime. So, it is desirable to configure the air flow though a cleaner head in such a way that air flow velocities are high enough so that dirt released from a floor surface is entrained in the air flow effectively and retained in the air flow at least until the air is discharged from the cleaner head.

It is against this background that the invention has been devised.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a cleaner head fora vacuum cleaning appliance, the cleaner head comprising a main body supporting an elongate agitator bar, wherein the elongate agitator bar comprises a rotatable cylindrical body having a first agitator formation extending outwardly therefrom, and wherein the cylindrical body defines a first channel that extends along the cylindrical body adjacent the first agitator formation, wherein the first channel extends around the cylindrical body helically and includes: a first channel portion extending around the cylindrical body in a first helical direction and a second channel portion extending around the cylindrical body in a second helical direction that is counter to the first helical direction, and wherein the first and second channel portions meet to define an apex of the first channel. This arrangement encourages a proportion of the air flow through the cleaner head to flow along the first channel, increasing the velocity of the air flow adjacent the first agitator formation and improving entrainment of dirt and dust particles made airborne by the first agitator formation. That is, some of the air flow through the cleaner head is concentrated in an area of the elongate agitator bar adjacent the first agitator formation to entrain dirt and dust particles made airborne by the first agitator formation and prevent them from returning to the floor surface. That the first and second channel portions meet to define an apex improves the effectiveness of the cleaner head since entrained dirt and dust particles are channelled to a point in the cleaner head where they are less likely to be redeposited on the floor surface and/ or within the cleaner head itself.

Preferably, the first channel has a uniform cross section along its length. This arrangement maintains the air flow velocity in the first channel.

Preferably, the bases of the first and second channel portions of the first channel comprise a concave profile extending along their respective lengths. This avoids areas within the first channel with little or no air flow, which could result in the accumulation of dirt and dust particles within the first channel.

Preferably, the apex is located substantially at the centre of the elongate agitator bar. Positioning the apex at the centre of the elongate agitator bar improves the effectiveness of the cleaner head since the pick-up of dirt and dust particles from the floor surface overtime is more uniform across the length of the elongate agitator bar.

Preferably, the apex points in the direction of rotation of the elongate agitator bar. Alternatively in use the apex may point away from the direction of rotation of the agitator bar. Preferably, the first agitator formation comprises first and second agitator rows, wherein the first agitator row extends from an first edge of the cylindrical body towards its centre in a first helical direction and the second agitator row extends from a second edge of the cylindrical body towards its centre in a second helical direction, and wherein the first and second rows meet in the centre of the elongate agitator bar with respect to its longitudinal axis to define an apex. This arrangement serves to guide the air flow through the cleaner head, improving the effectiveness of the cleaner head.

Preferably, the apex of the first agitator formation points in the direction of the rotation of the elongate agitator bar. Positioning the apex at the centre of the agitator further improves the effectiveness of the cleaner head since the pick-up of dirt and dust particles from the floor surface over time is more uniform across the length of the agitator.

Preferably, the first agitator formation includes at least one of a strip of stiff bristles, soft filaments or continuous material. This arrangement improves the versatility of the cleaner head, as its effectiveness for picking up dirt and dust particles is maintained across different surface types. Stiff agitator formations can, in use, dislodge stubborn dirt particles from carpeted floor surfaces, so that the dirt particles can be more easily entrained in the air flow through the suction opening. Whereas, relatively more deformable agitators act to sweep dirt and dust particles, particularly fine dust particles, from hard floor surfaces.

Preferably, the first agitator formation is made of carbon fibre and/ or nylon.

Preferably, the cylindrical body includes a second channel that extends along the cylindrical body adjacent to the first agitator formation on the opposite side thereof from the first channel. This arrangement increases the velocity of the air flow both sides of the first agitator formation, further improving entrainment of dirt and dust particles made airborne by the first agitator formation.

Preferably, the second channel includes a first channel portion extending around the cylindrical body in a first helical direction and a second channel portion extending around the cylindrical body in a second helical direction that is counter to the first helical direction, and wherein the first channel portion and the second channel portion of the second channel meet at an apex of the second channel. This arrangement further improves the effectiveness of the cleaner head since entrained dirt and dust particles are channelled to a point in the cleaner head where they are less likely to be redeposited on the floor surface and/ or within the cleaner head itself.

Preferably, the second channel has a uniform cross section along its length. This arrangement maintains the air flow velocity in the second channel.

Preferably the bases of the first and second channel portions of the second channel comprise a concave profile extending along their respective lengths. This avoids areas within the second channel with little or no air flow, which could result in the accumulation of dirt and dust particles within the second channel.

Preferably, the apex of the second channel is located substantially at the centre of the elongate agitator bar. Positioning the apex at the centre of the elongate agitator bar improves the effectiveness of the cleaner head since the pick-up of dirt and dust particles from the floor surface over time is more uniform across the length of the elongate agitator bar.

Preferably, the apex of the second channel points in the direction of rotation of the elongate agitator bar.

Preferably, the elongate agitator bar further comprises a second agitator formation extending outwardly from the cylindrical body. This arrangement improves the effectiveness of the cleaner head by providing an additional agitator formation for displacing dirt and dust particles from the floor surface.

Preferably, the second agitator formation extends along the body adjacent the first channel on the side of the first channel opposite from the first agitator formation.

Preferably, the second agitator formation comprises first and second agitator rows, wherein the first agitator row extends from an first edge of the cylindrical body towards its centre in a first helical direction and the second agitator row extends from a second edge of the cylindrical body towards its centre in a second helical direction, and wherein the first and second rows meet in the centre of the elongate agitator bar with respect to its longitudinal axis to define an apex. Preferably, the apex of the second agitator formation point in the direction of the rotation of the elongate agitator bar.

Preferably, the second agitator formation includes at least one of a strip of stiff bristles, soft filaments or continuous material. As with the first agitator formation, this arrangement improves the versatility of the cleaner head, as its effectiveness for picking up dirt and dust particles is maintained across different surface types.

Preferably, the second agitator formation is made of carbon fibre and/ or nylon.

Preferably, the elongate agitator bar is housed within an agitator chamber defined by the main body of the cleaner head, and wherein the agitator chamber is configured to define an interior surface that has a generally cylindrical portion which has a clearance of between 0.5mm and 2mm with the first and/ or second agitator formations. However, in instances where the first and/ or second agitator formations are made of carbon fibre, the clearance may be zero. That is, the first and/ or second agitators are configured to contact the cylindrical portion of the interior surface of the agitator chamber during use.

Preferably, the first agitator formation is fixed rigidly with respect to the first channel.

Preferably, the main body comprises a suction opening through which the agitator partially extends.

According to a second aspect of the invention, there is provided a vacuum cleaning appliance comprising a cleaner head according to the first aspect.

According to a third aspect of the invention, there is provided an elongate agitator bar for use in a cleaner head according to the first aspect, the elongate agitator bar comprising a rotatable cylindrical body having a first agitator formation extending outwardly therefrom, and wherein the cylindrical body defines a first channel that extends along the cylindrical body adjacent to the first agitator formation, wherein the first channel extends around the cylindrical body helically and includes a first channel portion extending around the cylindrical body in a first helical direction and a second channel portion extending around the cylindrical body in a second helical direction that is counter to the first helical direction, and wherein the first and second channel portions meet to define an apex of the first channel.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/ or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/ or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/ or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a front perspective view of a vacuum cleaner comprising a cleaner head in accordance with an embodiment of the invention;

FIG. 2 is a front perspective view of the cleaner head of FIG. 1 ;

FIG. 3 is a bottom view of the cleaner head of FIG. 1 ;

FIG. 4 shows an embodiment of an agitator for use in the cleaner head of FIG. 1 ;

FIG. 5a is a bottom view of the cleaner head with the agitator of FIG. 3 in a first position; FIG. 5b is a bottom view of the cleaner head with the agitator of FIG. 3 in a second position;

FIG. 6 is a second embodiment of the agitator for use in the cleaner head of FIG. 1 ;

FIG. 7 is a third embodiment of the agitator for use in the cleaner head of FIG. 1 ; and, FIG. 8 is a fourth embodiment of the agitator for use in the cleaner head of FIG. 1 .

In the drawings, like features are denoted by like reference signs.

SPECIFIC DESCRIPTION

A specific embodiment of the invention will now be described in which numerous features will be discussed in detail in order to provide a thorough understanding of the inventive concept as defined in the appended claims. However, it will be apparent to the skilled person that the invention may be put in to effect without the specific details and that in some instances, well known methods, techniques and structures have not been described in detail in order not to obscure the invention unnecessarily. Moreover, references in the following description to “left”, “right” and any other terms having an implied orientation are not intended to be limiting, and refer only to the orientation of the features as shown in the accompanying drawings.

FIG. 1 shows a vacuum cleaning appliance or vacuum cleaner 2 comprising a dirt and dust separating unit 4, a motor-driven fan unit 6 and a cleaner head 10 in accordance with an embodiment of the invention. The vacuum cleaner 2 further comprises a wand 8 connecting the dirt and dust separating unit 4 and the cleaner head 10. The motor-driven fan unit 6 draws dirt bearing air through the cleaner head 10, from a surface to be cleaned, such as a floor surface, to the dirt and dust separating unit 4, where dirt and dust particles are separated from the dirt-bearing air and the comparatively clean air is expelled from the vacuum cleaner 2. The dirt and dust separating unit 4 shown in this example is a cyclonic separating unit, but it will be understood by the skilled person that the separating unit 4 is not material to the invention and that the cyclonic separating unit could be replaced with an alternative separating unit or a combination of different separating units. Similarly, the nature of the vacuum cleaner 2 is not material to the invention. The vacuum cleaner 2 shown in FIG. 1 is a stick vacuum cleaner, but it will be understood that the cleaner head 10 disclosed herein may be used with other types of vacuum cleaners such as, for example, upright or cylinder vacuum cleaners.

With reference to FIG. 2, the cleaner head 10 comprises a main body 12 rotatably attached to a coupling 14. The coupling 14 is configured to be removably connectable to the wand 8, a hose or other such duct of a vacuum cleaner. It will be apparent to the skilled person, however, that the invention is also intended to cover cleaner heads that are configured to be permanently fixed to their respective vacuum cleaners.

The main body 12 comprises a housing 16, comprising an upper section 18 and a lower plate or sole plate 20, which defines a generally rectangular suction opening 22 through which dirt-bearing air enters the cleaner head 10 from the floor surface. The housing 16 defines a suction passage extending through the internal volume of the main body 12 from the suction opening 22 to an outlet duct 24 centrally located at a rear section 26 of the housing 16. The coupling 14 comprises a conduit, supported by a rolling assembly 28 for supporting the cleaner head 10 on a floor surface. The conduit comprises a forward portion connected to the outlet duct 24 and a rearward portion, pivotably connected to the forward portion. The part of the coupling 14 defining the rearward portion of the conduit comprises a fixing arrangement, generally designated by 30, for connecting a free end 15 of the coupling 14 to the wand 8. A rigid curved hose arrangement is held within and extends between the forward and rearward portions of the conduit.

With reference to FIG. 3, two wheels 32 are mounted within recessed portions in the bottom surface of the sole plate 20 for supporting the cleaner head 10 on the floor surface. The wheels 32 are configured to support the sole plate 20 above the floor surface when the cleaner head 10 is located on a hard floor surface, and, when the cleaner head 10 is located on a carpeted floor surface, to sink into the pile of the carpet to enable the bottom surface of the sole plate 20 to engage the fibres of the carpet. The sole plate 20 may be moveable relative to the housing 16, allowing it to ride smoothly over the carpeted floor surface during cleaning. The internal volume of the main body 12 comprises an agitator chamber 34, which is partially defined by the upper section 18 of the housing 16. An elongate brush or agitator bar 36 is mounted within the agitator chamber 34 and rotatable about its longitudinal axis for agitating dirt and dust particles located on the floor surface. The agitator chamber 34 defines an interior surface that has a generally cylindrical portion. The main body 12 further comprises two end caps 38, 40 mounted on the housing 16 at each end of the agitator chamber 34 for rotatably supporting the elongate agitator bar 36 within the agitator chamber 34. Preferably, at least one of the end caps 38, 40 is detachable from the housing 16, providing access to the agitator chamber 34 so that the elongate agitator bar 36 can be removed from and subsequently replaced within the agitator chamber 34. In the embodiment shown, a recessed portion 37 in the form of a keyway is provided in the end cap 40 for facilitating its removal from the housing 16 for accessing the agitator chamber 34. The elongate agitator bar 36 houses an electric motor and a drive mechanism, which connects the elongate agitator bar 36 to the electric motor for driving the elongate agitator bar 36 about its longitudinal axis. Such agitator drive arrangements are known, and so will not be explained in further detail here.

With reference to FIG. 4, the elongate agitator bar 36 comprises a hollow, rotatable cylindrical body 42 bearing first and second elongate agitator formations, generally designated by 44 and 46 respectively. The first and second agitator formations 44, 46 each comprise a plurality of agitators, extending outwardly from the outermost radial surface of the cylindrical body 42, and configured to protrude from the suction opening 22 when the elongate agitator bar 36 is mounted in the agitator chamber 34 for agitating dirt and dust particles located on the floor surface as the elongate agitator bar 36 is rotated by the electric motor. The agitators have a base fixed to the cylindrical body 42, by means of a retaining member (not shown), and are configured to rotate with the cylindrical body 42 when the electric motor drives the elongate agitator bar 36. The agitators may include a plurality of soft filaments, having tips that can flex relative to the cylindrical body 42 upon contact with the floor surface, stiff bristles or a strip of continuous material, and may be made of carbon fibre or nylon, to name two common material examples. Furthermore, instead of a continuous strip of bristles or filaments, as shown here, the agitator rows could be made up of a row of discrete tufts of bristles or filaments. In embodiments where the agitators are made of nylon, the clearance formed between their outer radial ends and the cylindrical portion of the interior surface of the agitator chamber 34 is preferably in the range of 0.5mm to 2mm when the elongate agitator bar 36 is supported within agitator chamber 34. However, in embodiments where the agitators are made of carbon fibre, the agitators are configured so as to extend outwardly from the outermost radial surface of the cylindrical body 42 at an angle, such they are inclined away from the direction in which the elongate agitator bar 36 rotates, and so that their radial ends contact the cylindrical portion of the interior surface of the agitator chamber 34.

The first agitator formation 44 comprises two agitator rows 48, 49 starting from either the left- or right-side edge L, R of the cylindrical body 42 and extending partially around the cylindrical body 42 towards the centre of the elongate agitator bar 36 (with respect to the longitudinal axis of the elongate agitator bar 36), shown with a line designated by C. Similarly, the second agitator formation 46 also comprises two agitator rows 50, 51 starting from either the left- or right-side edge L, R of the cylindrical body 42, diametrically opposite the two agitator rows 48, 49 of the first agitator formation 44, and extending partially around the cylindrical body 42 towards the centre C of the elongate agitator bar 36. In other embodiments, the agitator rows 48, 49, 50, 51 may start from a region of the cylindrical body 42 adjacent the left- or right-side edges L, R rather than from the edges L, R themselves. The two agitator rows 48, 49, 50, 51 in each agitator formation 44, 46 extend around the elongate agitator bar 36 in helical directions that are counter to each other to form two angularly spaced chevrons 52, 54. That is, one agitator row 49, 51 in each agitator formation 44, 46 extends helically around the cylindrical body 42 in a first helical direction and the other agitator row 48, 50 extends helically around the cylindrical body 42 in a second helical direction that is opposite, i.e. counter, to the first helical direction. In this illustrated embodiment, it will be appreciated that each agitator row 48, 49, 50, 51 circumferentially extends across half the outer radial surface of the cylindrical body 42, starting from a respective left- or right-side edge L, R and ending at the centre C of the cylindrical body 42. It will also be noted that each agitator row 48, 49, 50, 51 in one agitator formation 44, 46 is parallel with its equivalent agitator row 48, 49, 50, 51 in the other agitator formation 44, 46. The skilled reader will appreciate however that other arrangements are possible in which equivalent agitator rows 48, 49, 50, 51 extend around the cylindrical body 42 in a divergent or convergent arrangement.

With reference to the longitudinal axis of the elongate agitator bar 36, the axially inner ends of the agitator rows 48, 49, 50, 51 in each chevron 52, 54 are aligned to form apices 56, 57 at the centre C of the elongate agitator bar 36. When the elongate agitator bar 36, and cleaner head 10 in general, is viewed from below, as shown in FIG. 3, the apex 56 that is seen through the suction opening 22 points towards the rear section 26 of the housing 16, and specifically the outlet duct 24. This configuration functions to channel airflow from the suction opening 22 through the centre of the cleaner head 10 to the outlet duct 24, as opposed to a standard helical agitator brush formation, which acts like a screw pump to move air from one side of the cleaner head 10 to the other side. This can result in an inconsistent air flow distribution through the suction opening 22, causing dirt and dust particles to accumulate in areas within the cleaner head 10 or be redeposited onto the floor surface. Guiding or channelling the airflow through the centre of the cleaner head 10 to the outlet duct 24, however, improves the effectiveness of the cleaner head 10 because the pick-up of dirt and dust particles from the floor surface over time is more uniform across the entire suction opening 22. In the present embodiment, the apices 56, 57 of each chevron 52, 54 points in the direction in which the elongate agitator bar 36 is configured to rotate. However, the improvements brought about by the apices 56, 57 pointing towards the outlet duct 24, when the cleaner head 10 is viewed from below, are also realised regardless of the direction in which the agitator 36 is configured to rotate.

In order to increase the airflow velocity in regions of the cleaner head 10, and so further improve the pick-up of dirt and dust particles, the elongate agitator bar 36 comprises at least one channel recessed in the outer radial surface of and extending along the cylindrical body 42 adjacent an agitator formation. That is, the at least one channel is not located away from but is near or next to the agitator formation 44. In other words there is no gap between the channel and the agitator formation. The embodiment shown in FIG. 4 comprises first and second channels 58, 60, positioned either side of the first agitator formation 44. With reference again to the longitudinal axis of the elongate agitator bar 36, the first channel 58 is located adjacent the axially outer sides of the agitator rows 48, 49 and comprises first and second channel portions 62, 64 starting from at or near either the left- or right-side edge L, R of the cylindrical body 42. The first channel portion 62 extends partially around the cylindrical body 42 in a first helical direction towards the centre C of the elongate agitator bar 36, whereas the second channel portion 64 extends partially around the cylindrical body 42 in a second helical direction, opposite to the first helical direction. The axially inner ends of the first and second channel portions 62, 64 align to form an apex 66 at the centre C of the elongate agitator bar 36, positioned ahead of the apex 56 of the first agitator formation 44 with respect to the direction in which the elongate agitator bar 36 rotates. The second channel 60 is located adjacent the axially inner sides of the agitator rows 48, 49. The second channel 60 also comprises first and second channel portions 68, 70 starting from either the left- or right-side edge L, R of and extending partially around the cylindrical body 42 in opposing helical directions to form an apex 67 at the centre of the C of the elongate agitator bar 36. The apex 67 of the second channel 60 is positioned behind the apex 56 of the first agitator formation 44 with respect to the direction in which the elongate agitator bar 36 rotates, and is best seen in FIG. 5b. The respective cross sections of the first and second channels 58, 60 are uniform along their length.

With reference to the expanded view in FIG. 4, which shows the agitator row 48 extending outwardly from the outermost radial surface of the cylindrical body 42 between the channels 58, 60, in use, the downwardly facing sections of the channels 58, 60 lie adjacent the floor surface, shown with a dashed line designated by F. The proximity of the floor surface at least partially closes the channels 58, 60, which encourages a proportion of the air flow through the suction opening 22 to flow along the channels 58, 60. This increases the velocity of the air flow adjacent the first agitator formation 44 and further improves the entrainment of dirt and dust particles made airborne by the first agitator formation 44. That is, some of the air flow through the suction opening 22 is concentrated in an area of the elongate agitator bar 36 adjacent the first agitator formation 44 to entrain dirt and dust particles made airborne by the first agitator formation 44 and prevent them from returning to the floor surface. The base 61 of each channel 58, 60 has a trough-like or concave profile, defining a radius at the intersections between the base 61 and the side walls of the channel 58, 60. This avoids areas within the channels 58, 60 with little or no air flow, which could result in the accumulation of dirt and dust particles within the channels 58, 60.

As can be seen particularly clearly in FIG. 4, the cylindrical body 42 of the elongate agitator bar 36 is otherwise devoid of features other than the channels 58, 60 and the agitator formations 44, 46, and the radially-extending side walls of the channels immediately border the radially outer surface of the cylindrical body 42. Since the outer surface of the cylindrical body 42 forms a close clearance with the interior surface of the agitator chamber 34, the otherwise featureless outer surface of the cylindrical body 42 further encourages air flow to accelerate into the channels 58, 60 as they establish an effective ‘path of least resistance’. The configuration of the cylindrical body 42 and the channels 58, 60 therefore provide a beneficial arrangement to direct high speed air flow through the channels 58, 60 in preference to generalised air flow around the cylindrical body 42.

FIG. 5a shows the underside of the cleaner head 10 with the elongate agitator bar 36 in a first position, whereas FIG. 5b shows the elongate agitator bar 36 in a second position, in which the elongate agitator bar 36 has been rotated 180 degrees from the first position. It can be seen from these figures that in both rotational positions, and therefore all of the intermediate rotational positions, the channels 58, 60 are arranged to guide the air flow entering the suction opening 22 directly towards the outlet duct 24 located at a rear section 26 of the housing 16, as indicated by the series of arrows. This arrangement provides the shortest path for dirt and dust particles from the point of their entrainment into the air flow through the channels 58, 60 to the outlet duct 24, thereby minimising the possibility of inadvertently depositing dirt and dust particles within the cleaner head 10 and/ or redepositing them onto the floor surface. In effect, therefore, the channels 58, 60 establish an air flow corridor which encourages the air flow through the cleaner head 10 to converge from axially separated positions where air may enter the cleaner head 10 to a convergence point near to the outlet duct 24. This improves the flow of air through the cleaner head 10 and improves pick-up performance.

FIG. 6 shows a second embodiment of the elongate agitator bar 36 for use in the cleaner head 10. This embodiment is substantially the same as the previous embodiment of the elongate agitator bar 36 except that it only includes a single agitator formation 44. The agitator formation 44 comprises one agitator row 49 extending helically around the cylindrical body 42 in a first helical direction and another agitator row 48 extending helically around the cylindrical body 42 in a second helical direction that is opposite to the first helical direction, forming a chevron 52. The axially inner ends of the agitator rows 48, 49 align to form an apex 56 at the centre of the elongate agitator bar 36, pointing in the direction in which the elongate agitator bar 36 is configured to rotate.

The elongate agitator bar 36 further comprises two channels 58, 60 recessed in the outer radial surface of the cylindrical body 42. The first channel 58 is located adjacent the axially outer sides of the agitator rows 48, 49 and comprises first and second channel portions 62, 64 starting from either the left- or right-side edge L, R of the cylindrical body 42. The first channel portion 62 extends partially around the cylindrical body 42 in the first helical direction towards the centre of the elongate agitator bar 36, whereas the second channel portion 64 extends partially around the cylindrical body 42 in the second helical direction, opposite to the first helical direction. The axially inner ends of the first and second channel portions 62, 64 align to form an apex 66 (not shown) at the centre of the elongate agitator bar 36, positioned ahead of the apex 56 of the first agitator formation 44 with respect to the direction in which the elongate agitator bar 36 rotates. The second channel 60 is located adjacent the axially inner sides of the agitator rows 48, 49. The second channel 60 also comprises first and second channel portions 68, 70 starting from either the left- or right-side edge L, R of and extending partially around the cylindrical body 42 in opposing helical directions to form an apex 67 at the centre of the of the elongate agitator bar 36. The apex 67 of the second channel 60 is positioned behind the apex 56 of the first agitator formation 44 with respect to the direction in which the elongate agitator bar 36 is configured to rotate.

It should be noted that in the embodiments of FIGS. 4 and 6, the channels 58, 60 flank both sides of the agitator rows 48, 49. However, other embodiments are possible in which channels only run along one side of an agitator row. Some variants of this will now be described.

FIG. 7 shows a third embodiment of the elongate agitator bar 36 for use in the cleaner head 10. This embodiment is substantially the same as the first embodiment, except that it only includes a single channel 58 comprising first and second channel portions 62, 64 respectively positioned adjacent the axially outer side of the agitator rows 49, 48 forming the first agitator formation 44. The first channel portion 62 extends partially around the cylindrical body 42 in the first helical direction towards the centre of the elongate agitator bar 36, whereas the second channel portion 64 extends partially around the cylindrical body 42 in the second helical direction, opposite to the first helical direction. The axially inner ends of the first and second channel portions 62, 64 align to form an apex 66 at the centre of the elongate agitator bar 36, positioned ahead of an apex 56 of the first agitator formation 44 with respect to the direction in which the elongate agitator bar 36 is configured to rotate.

FIG. 8 shows a fourth embodiment of the elongate agitator bar 36 for use in the cleaner head 10. This embodiment is substantially the same as the first embodiment, except that it only includes a single channel 60 comprising first and second channel portions 68, 70 respectively positioned adjacent the axially inner side of the agitator rows 49, 48 forming the first agitator formation 44. The first channel portion 68 extends partially around the cylindrical body 42 in the first helical direction towards the centre of the elongate agitator bar 36, whereas the second channel portion 70 extends partially around the cylindrical body 42 in the second helical direction, opposite to the first helical direction. The axially inner ends of the first and second channel portions 68, 70 align to form an apex 67 at the centre of the elongate agitator bar 36, positioned behind an apex 56 of the first agitator formation 44 with respect to the direction in which the elongate agitator bar 36 is configured to rotate.

Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the appended claims. For example, all of the embodiments of the elongate agitator bar 36 comprise a rotatable cylindrical body 42 having at least one agitator formation 44 and at least one channel 58, 60 extending along the cylindrical body 42, in a chevron formation, adjacent the agitator formation 44. Alternative embodiments may include an additional agitator formation positioned adjacent the channel 58, 60 on the side of the channel 58, 60 opposite to where the agitator formation 44 is positioned. With reference to FIG. 8, for example, this would mean an embodiment of the elongate agitator bar 36 comprising an additional agitator formation positioned between the first and second agitator formations 44, 46 and extending along the axially inner edge of the channel 60. In this embodiment, the additional agitator formation would comprise an apex at the centre of the elongate agitator bar 36 positioned behind the apex 67 formed by channel 60 with respect to the direction in which the elongate agitator bar 36 is configured to rotate, and provide increased mechanical action acting against the floor surface for displacing dirt and dust particles.

Moreover, in all of the embodiments shown, the apices 56, 57 of the first and second agitator formations 44, 46 and the apices 66, 67 of the first and second channels 58, 60 are formed at the centre of the elongate agitator bar 36. In alternative embodiments, one or more of the first and second agitator formations 44, 46, and the first and second channels 58, 60 could be configured such that their respective apex 56, 57, 66, 67 is formed off centre. That is, one or more of the apices 56, 57, 66, 67 is formed away from the centre of the elongate agitator bar 36.

Claims

1. A cleaner head (10) for a vacuum cleaning appliance, the cleaner head (10) comprising: a main body (12) supporting an elongate agitator bar (36), wherein the elongate agitator bar (36) comprises a rotatable cylindrical body (42) having a first agitator formation (44) extending outwardly therefrom, and wherein the cylindrical body (42) defines a first channel (58) that extends along the cylindrical body (42) adjacent the first agitator formation (44), wherein the first channel (58) extends around the cylindrical body (42) helically and includes: a first channel portion (62) extending around the cylindrical body (42) in a first helical direction and a second channel portion (64) extending around the cylindrical body (42) in a second helical direction that is counter to the first helical direction, and wherein the first and second channel portions (62, 64) meet to define an apex (66) of the first channel (58).

2. A cleaner head (10) according to claim 1 , wherein the first channel (58) has a uniform cross section along its length.

3. A cleaner head (10) according to claim 1 or 2, wherein the bases (61) of the first and second channel portions (62, 64) of the first channel (58) comprise a concave profile extending along their respective lengths.

4. A cleaner head (10) according to any preceding claim, wherein the apex (66) is located substantially at the centre (C) of the elongate agitator bar (36).

5. A cleaner head (10) according to any preceding claim, wherein the apex (66) points in the direction of rotation of the elongate agitator bar (36).

6. A cleaner head (10) according to any preceding claim, wherein the first agitator formation (44) comprises first and second agitator rows (48, 49), wherein the first agitator row (49) extends from an first edge (L) of the cylindrical body (42) towards its centre (C) in a first helical direction and the second agitator row (48) extends from a second edge (R) of the cylindrical body (42) towards its centre (C) in a second helical direction, and wherein the first and second rows (48, 49) meet in the centre (C) of the elongate agitator bar (36) with respect to its longitudinal axis to define an apex (56).

7. A cleaner head (10) according to claim 6, wherein the apex (56) of the first agitator formation (44) points in the direction of the rotation of the elongate agitator bar (36).

8. A cleaner head (10) according to any preceding claim, wherein the first agitator formation (44) includes at least one of a strip of stiff bristles, soft filaments or continuous material.

9. A cleaner head (10) according to any preceding claim, wherein the first agitator formation (44) is made of carbon fibre and/ or nylon.

10. A cleaner head (10) according to any preceding claim, wherein the cylindrical body (42) includes a second channel (60) that extends along the cylindrical body (42) adjacent to the first agitator formation (44) on the opposite side thereof from the first channel (58).

11. A cleaner head (10) according to claim 10, wherein the second channel (60) includes a first channel portion (68) extending around the cylindrical body (42) in a first helical direction and a second channel portion (70) extending around the cylindrical body (42) in a second helical direction that is counter to the first helical direction, and wherein the first channel portion (68) and the second channel portion (70) of the second channel (60) meet at an apex (67) of the second channel (60).

12. A cleaner head (10) according to claim 10 or 11 , wherein the second channel (60) has a uniform cross section along its length.

13. A cleaner head (10) according to claim 11 or 12, wherein the bases (61) of the first and second channel portions (68, 70) of the second channel (60) comprise a concave profile extending along their respective lengths.

14. A cleaner head (10) according to any one of claims 11 to 13, wherein the apex (67) of the second channel (60) is located substantially at the centre (C) of the elongate agitator bar (36).

15. A cleaner head (10) according to any one of claims 11 to 14, wherein the apex (67) of the second channel (60) points in the direction of rotation of the elongate agitator bar (36).

16. A cleaner head (10) according to any preceding claim, further comprising a second agitator formation (46) extending outwardly from the cylindrical body (42).

17. A cleaner head (10) according to claim 16, wherein the second agitator formation (46) extends along the body (42) adjacent the first channel (58) on the side of the first channel (58) opposite from the first agitator formation (44).

18. A cleaner head (10) according to any preceding claim, wherein the elongate agitator bar (36) is housed within an agitator chamber (34) defined by the main body (12) of the cleaner head (10), and wherein the agitator chamber (34) is configured to define an interior surface that has a generally cylindrical portion which has a clearance of between 0.5mm and 2mm with the first and/ or second agitator formations (44, 46).

19. A cleaner head (10) according to any preceding claim, wherein the first agitator formation (44) is fixed rigidly with respect to the first channel (58).

20. A vacuum cleaning appliance comprising a cleaner head (10) according to any preceding claims.

21 . An elongate agitator bar (36) for use in a cleaner head (10) according to any one of claims 1 to 16, the elongate agitator bar (36) comprising: a rotatable cylindrical body (42) having a first agitator formation (44) extending outwardly therefrom, and wherein the cylindrical body (42) defines a first channel (58) that extends along the cylindrical body (42) adjacent to the first agitator formation (44), wherein the first channel (58) extends around the cylindrical body (42) helically and includes: a first channel portion (62) extending around the cylindrical body (42) in a first helical direction and a second channel portion (64) extending around the cylindrical body (42) in a second helical direction that is counter to the first helical direction, and wherein the first and second channel portions (62, 64) meet to define an apex (66) of the first channel (58).