VACUUM CLEANER HEAD HAVING AGITATOR ELEMENT AND RIB

Abstract

A cleaner head for a vacuum cleaner, the cleaner head having a housing defining a suction chamber comprising an outlet, and an agitator element mounted to the housing for rotation about a first axis such that the agitator comprises a first, free end and a second end. The housing comprises at least one rib extending within the housing along a helical, spiral, or angled path, the rib contacting the agitator element, such that, in use, hair picked up by the agitator element is moved axially towards the first end by the at least one rib as the agitator element rotates.

Claims

1. A cleaner head for a vacuum cleaner, the cleaner head comprising: a housing defining a suction chamber comprising an outlet; and an agitator element, the agitator element being mounted to said housing for rotation about a first axis such that the agitator element comprises a first, free end and a second end; wherein the housing comprises at least one rib extending within the housing along a helical, spiral, or angled path, the rib contacting the agitator element, such that, in use, hair picked up by the agitator element is moved axially towards the first end by the at least one rib as the agitator element rotates.

2. The cleaner head of claim 1, wherein the at least one rib comprises a contact face on a side of the rib facing the first end, the contact face being inclined relative to an outer surface of the agitator element at inclination angle greater than 90 degrees.

3. The cleaner head of claim 2, wherein the inclination angle varies along at least part of a length of the rib.

4. The cleaner head of claim 3, wherein the rib comprises a leading portion and a trailing portion relative to the direction of rotation of the agitator element, and the inclination angle increases in a direction towards the trailing portion.

5. The cleaner head of claim 1, wherein the at least one rib is canted at a cant angle towards the first end, along at least part of a length of the rib.

6. The cleaner head of claim 5, wherein the cant angle varies along at least a part of the length of the rib's length.

7. The cleaner head of claim 2, wherein the contact face of the at least one rib includes, in cross section, an acutely angled corner for scraping hair from or along the agitator element.

8. The cleaner head of claim 1, wherein the at least one of the ribsrib includes a ramped leading portion.

9. The cleaner head of claim 1, including a plurality of the ribs, wherein ends of adjacent ribs overlap with each other, such that, in use, hair picked up by the agitator element is moved from rib to rib as the agitator element rotates.

10. The cleaner head of claim 1, wherein the agitator element has a shape that tapers towards the first end in a direction along the first axis.

11. The cleaner head of claim 1, wherein contact pressure between the at least one rib and the outer surface increases closer to the first end.

12. The cleaner head of any preceding claim 1, comprising a plurality of the at least one rib, wherein the ribs are axially more closely spaced towards the first end.

13. The cleaner head of any preceding claim 1, comprising a plurality of the least one rib, wherein the ribs overlap axially to a greater extent towards the first end.

14. The cleaner head of claim 1, wherein the at least one rib traces a helix of a single, constant axial pitch.

15. The cleaner head of claim 1, wherein the at least one rib traces a varying angle relative to the housing.

16. The cleaner head of claim 1, comprising a motor for rotating the agitator element in use.

17. The cleaner head of claim 1, wherein the agitator element comprises a textile covering or bristles disposed on the outer surface.

18. (canceled)

19. The cleaner head of claim 1, wherein the outer surface is resiliently compressible.

20. The cleaner head of claim 19, wherein a distance by which the at least one rib compresses the resiliently compressible material increases closer to the first end.

21. The cleaner head of any preceding claim 1, comprising a further agitator element, wherein agitator element and the further agitator element are adjacent to each other and axes of rotation of the agitator element and the further agitator element are disposed within a common plane.

22. (canceled)

23. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various aspects and implementations will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0033] FIG. 1 is a perspective view of a vacuum cleaner according to an aspect;

[0034] FIG. 2 is a perspective view of a cleaner head according to a further aspect;

[0035] FIG. 3 is a top perspective view of the cleaner head of FIG. 2;

[0036] FIG. 4 is a section through IV-IV of FIG. 3, including a schematic representation of a motor;

[0037] FIG. 5 is an underside view of cover elements of the cleaner head of FIG. 2;

[0038] FIG. 6 is a detailed view of the circled portion of FIG. 5;

[0039] FIGS. 7-9 are detailed views of the circled portions of FIG. 4;

[0040] FIG. 10 is a partially see-through front perspective view of the cleaner head of FIG. 2;

[0041] FIGS. 11-14 are underside views of alternative cover elements for use with a cleaner head;

[0042] FIG. 15 schematically shows rib-spacing relative to a cover element;

[0043] FIG. 16 schematically shows part of a manufacturing process for the cover element of

[0044] FIG. 15; and

[0045] FIG. 17 is the detailed view of circled portion VIII of FIG. 8, illustrating various rib angles.

DETAILED DESCRIPTION

[0046] FIG. 1 shows a hand-held vacuum cleaner 2 according to an implementation of the disclosure and comprising a main body 4, a wand 6 and a cleaner head 20. The main body 4 comprises a separating system 10, in the form of a cyclonic separator, a motor and impeller (not visible) arranged to draw air through the separating system 10, and a power supply 12, in the form of a battery, for powering the motor. The main body 4 has a handle 14 which is gripped by a user, and a clean air outlet 16 through which air that has passed through the separating system 10 is discharged. The wand 6 is attached at one end to the main body 4 and at the other end to the cleaner head 20. The wand 6 provides fluid communication between the cleaner head 20 and the separating system 10, and supports the cleaner head 20 during use.

[0047] FIG. 2 shows a cleaner head 20 according to implementations of the disclosure. The cleaner head 20 comprises a first agitator element 22 and a second agitator element 24. The first and second agitator elements 22, 24 are each mounted for rotation about their respective axes R1, R2 (as shown in FIG. 4). Each agitator element 22, 24 comprises a first, free end 26a, 26b and a second end 28a, 28b at which they are mounted to the cleaner head 20. Each agitator element has a shape which tapers towards the first end 26a, 26b in a direction along the axis of rotation R1, R2. In the illustrated implementation, the agitator elements 22, 24 are generally frusto-conical in shape. However, it should be appreciated that a portion of one or both agitator elements 22, 24 may not be tapered. For example, the shape of one or both agitator elements 22, 24 may comprise a cylindrical portion combined with a frusto-conical portion, a cylindrical portion, or any other suitable cross-section.

[0048] With reference to FIG. 4, the cleaner head 20 comprises a drive for driving rotation of the 35 agitator elements 22, 24. In the implementation of FIG. 4, the drive comprises a motor 38 arranged to drive rotation of the first and second agitator elements 22, 24. The motor 38 is partially disposed within the cores of the agitator elements 22, 24.

[0049] Motor 38 includes an integrated transmission in the form of a gearbox (not shown), which steps down the angular rotation rate and outputs the motor's drive via output shafts 52, 54 that are angled to be concentric with the rotational axes R1, R2 of the respective agitator elements 22, 24. Output shaft 52 extends through first agitator element 22 and supports the first end 26a of the first agitator element 22. Output shaft 54 extends through second agitator element 24 and supports the first end 26b of the second agitator element 24. As well as transmitting torque from motor 38 to the agitator elements 22, 24, output shafts 52, 54 are effectively the sole support for cantilevered agitator elements 22, 24.

[0050] In other implementations, output shafts can terminate at the second ends of the agitator elements, such at the agitator elements support themselves in a cantilevered fashion without the first ends being connected to the output shafts.

[0051] In alternative implementations, each of the agitator elements 22, 24 can have its own motor, optionally including an integrated transmission.

[0052] Alternatively, one or more motors can be provided outside of the space defined by the inside of agitator elements 22, 24, and the drive provided from the motor(s) to the agitator elements 22, 24 by way of one or more driveshafts, linkages, gears, chains, pulleys, or other transmission means. In such implementations, agitator element 22, 24 can supported by, for example, a central hub (not shown) instead of the drive shafts. Optionally, such a hub can form part of the drive transmission means, including providing support to one or more transmission components such as driveshafts, linkages, gears, chains, pulleys, bearings, septic and the like.

[0053] The first and second agitator elements 22, 24 are cantilevered from opposite sides of the motor 38 at their respective second ends 28a, 28b. In the illustrated implementation, the motor 38 is at a laterally central position with respect to the overall cleaner head 20, although this may not always be the case. For example, if the first and second agitator elements 22, 24 have different lengths, then the motor 38 (or any other hub from which the agitator elements are cantilevered in other implementations) can be offset laterally relative to the laterally central part of the cleaner head 20.

[0054] The cleaner head 20 has a housing 32, which at least partially defines a suction chamber comprising an outlet 34 for expulsion of air and debris towards the vacuum cleaner 2. The suction chamber is delimited at the front by the agitator elements 22, 24.

[0055] The housing 32 comprises side openings 36, adjacent the first end 26a, 26b of each agitator element 22, 24. The first ends 26a, 26b of the agitator elements 22, 24 can project into or through the side openings 36. This enables the first ends 26a, 26b of the agitator elements 22, 24 to protrude beyond the footprint of the cleaner head housing 32, providing for a greater agitation width and up-to-the-edge cleaning.

[0056] The outer (that is, external) surfaces of the agitator elements comprise a compressible material in the form of a felt-like covering 66. However, the skilled person will appreciate that the agitator elements may have an outer surface comprising, or covered in, any suitable agitating material, which may optionally be resiliently compressible. The external surfaces can comprise, for example, a textile covering. In this context, textile is used in its broadest sense to include any form of flexible material, including woven and non-woven fabrics, felts, and/or foams, optionally combined into one or more layers. Alternatively, or in addition, each agitator element can comprise bristles disposed on the outer surface.

[0057] The agitating material can be formed from any suitable material or combination of materials, including natural or synthetic materials, composite materials including carbon fibre, and any suitable combination thereof.

[0058] The felt-like covering 66 is about 6 mm deep in the implementation of FIGS. 4-9, although any other suitable depth may be used, depending upon the implementation.

[0059] Any suitable combination of regions of different materials can be applied to the outside surface. For example, one or more strips (not shown) of relatively higher density, coarseness, and/or resiliency material may be applied between strips of lower density, coarseness, and/or resiliency material. Optionally, such strips may wind in a helical or spiral manner along each of the agitator elements 22, 24. The strips of relatively higher density, coarseness, and/or resiliency material can optionally be narrower than the strips of lower density, coarseness, and/or resiliency material.

[0060] As is most clearly illustrated in FIG. 4, which is a lateral sectional view of the cleaner head 20, each agitator element 22, 24 is arranged such that when the cleaner head 20 is applying suction to the horizontal surface S to be cleaned (e.g. hard flooring), the position of the axis R1, R2 at the first end 26a, 26b of each agitator element 22, 24 is closer to the surface S than the position of the axis R1, R2 at the second end 28a, 28b of each agitator element 22, 24. Therefore the agitator elements 22, 24 are effectively angled downwards (e.g. canted downwards), towards the surface S to be cleaned by the vacuum cleaner 2.

[0061] In the illustrated implementation, the downwards angling of the agitator elements 22, 24 is such that the lowermost portion of the external surface of each agitator element 22, 24 is parallel to the horizontal surface S when the cleaner head 20 is applying suction thereto. Furthermore, there is substantially no gap between the lowermost portions of the agitator elements 22, 24 at their second ends 28a, 28b, i.e. the lowermost portions of the agitator elements 22, 24 are in contact at their second ends 28a, 28b. This means that there is very little, if any, unagitated region of the surface S between the two agitator elements 22, 24 (i.e. in the region marked P in FIG. 4).

[0062] In this implementation the respective regions on the floor agitated by the two agitator elements touch each other so that there is effectively a single unitary (elongate) region agitated by the cleaner head on the floor at any given time. In general, this condition (the lowermost portions of the agitator elements being parallel to the floor) will be achieved when the agitator elements 22, 24 are angled downwards by an angle a which is equal to around half the cone angle of the frusto-conical agitator elements 22, 24. The tapering of the conical shape of the external surface of each agitator element has a taper angle which is equal to half the cone angle and thus in the illustrated implementation the same as the angle a by which the axis of the agitator element is angled downwards. In this implementation that angle a is about 7.5 degrees. Given that the external surface of each agitator element may have some resilience/deformability and that surfaces to be cleaned in practice are rarely perfectly flat, it will be appreciated that the lowermost portion need not be exactly parallel, in the strict mathematical sense, to the horizontal surface for the agitator element to cause agitation of the surface to be cleaned along substantially the entire length of the external surface of the element arranged to perform such agitating.

[0063] It should be appreciated that the agitator elements may not necessarily be angled downwards by an angle corresponding to half the cone angle of the agitator elements. In implementations, the agitator elements may have different lengths and/or different cone angles.

[0064] Accordingly, the first and second agitator elements may be angled downwards by different angles. In some implementations, the cleaner head 20 comprises a sole plate in which a suction opening is formed. The lowermost portion of the external surface of each agitator element may be parallel to the sole plate.

[0065] Turning to FIG. 5, there is shown an inside of cover elements 56, 58 of housing 32. FIG. 6 shows a detailed view of the region circled in FIG. 5. An inner profile of each of cover elements 56 is generally frusto-conical, so as to be generally complementary in shape to the outer surface of first and second agitator elements 22, 24. As best shown in FIG. 2, cover elements 56 partially cover an upper region of first and second agitator elements 22, 24.

[0066] Returning to FIGS. 5 and 6, several ribs 60 are disposed on an inner surface of cover element 56. Each of ribs 60 follows a generally spiral path within cover element 56. Ribs may be of different lengths. For example, in the implementation of FIGS. 4-9, ribs that are closer to side openings 36 extend almost the full width of cover elements 56, 58, whereas those further from side openings 36 traverse only a portion of that width. For example, inner ribs 70 furthest from side openings 36 on each cover element 56, 58 extend from roughly a centre to the edge of their corresponding cover element 56, 58. In certain implementations, this may reduce the amount of torque required to rotate agitator elements 22, 24 against ribs 60.

[0067] FIGS. 7 to 9 show detailed views of the ribs 60 circled (and respectively indicated by reference signs VII, VIII, and IX) in FIG. 4. Each of the ribs 60 is canted, in section, towards the first ends 26a, 26b of their respective cover elements 56. Each rib 60 comprises a contact face 68.

[0068] In the implementation of FIGS. 4-9, the contact face 68 of each rib 60 includes a rounded portion to reduce friction. The radius of such rounding may be selected as a compromise between reducing friction, and increasing effectiveness of the ribs in use, as described in more detail below. In other implementations, the contact face may include a relatively sharp edge.

[0069] Each rib 60 includes a ramped leading portion 62 and a trailing portion 63, as best shown in FIG. 6. This reduces the chance of hair and other material being snagged or otherwise captured at start of the rib, compared with having a sharp vertical start to each rib. The ramped leading portion 62 can also reduce friction as first and second agitator elements 22, 24 are rotated against ribs 60 within their respective cover elements 56, 58, because felt-like covering 66 is gradually compressed each time it encounters and moves onto ramped leading portion 62.

[0070] Each rib 60 is in contact with the agitator element 22, 24 to which it is adjacent. As explained above, the outer surfaces of the agitator elements 22, 24 comprise a felt-like covering 66 that is compressible. Ribs 60 are formed, in the illustrated implementation, of a relatively incompressible material, such as a polymeric material. As such, ribs 60 dig slightly into an outer surface of felt-like covering 66, as best shown in FIGS. 7-9.

[0071] FIG. 17 illustrates angles that may be associated with the rib(s) in various implementations. FIG. 17 corresponds with the detailed view VII shown in FIG. 7. The contact face 68 faces (at least obliquely) the first end 26a. The contact face 68 makes contact with an outer surface (in this case, felt-like covering 66) of the agitator element 22 at an inclination angle (line 92 is parallel to the outer surface of the agitator element 22).

[0072] Angle can be consistent along the full length of the rib 60. Alternatively, angle can vary along at least part of a length of the rib 60 towards the first end 26a. For example, angle can increase along at least some portion of the rib length towards first end 26a. In particular implementations, angle can increase along the entire length of the rib 60, optionally excluding the ramped leading portion 62.

[0073] The rib 60 in FIG. 17 is canted towards the first end 26a at a cant angle . Cant angle can be defined as the angle that a central line 94 through the rib 26 (in cross section) makes with a parallel 92 to the outer surface of the agitator element 22. Cant angle can be consistent along the full length of the rib 60. Alternatively, cant angle can vary along at least part of a length of the rib 60 towards the first end 26a. For example, cant angle can increase along at least some portion of the rib length towards first end 26a. In particular implementations, cant angle can increase along the entire length of the rib 60, optionally excluding the ramped leading portion 62.

[0074] An example of an implementation in which inclination angle and cant angle change along the length of the ribs is shown in FIG. 14. Both angle and cant angle increase along the length of the rib 60. The angle and cant angle are both almost perpendicular relative to a parallel to the outer surface of the agitator element at the beginning of the rib 60, and increase along the ribs' length. These increasing angles may help peel the hair away from the agitator element as it moves along the rib. This increases the chance of the hair eventually being disentangled from the felt-like covering 66 as it traverses the ribs 60, allowing the hair to potentially become a more compact mass that is more easily moved by subsequent ribs.

[0075] Optionally, ribs that are closer to side openings 36 may dig more deeply into the outer surface of felt-like covering 66. In the implementation of FIGS. 4-9, this is achieved by ribs 60 becoming taller, in section, as they get closer to side openings 36, while the inner surface of cover elements 56, 58 from which ribs 60 extend maintains a relatively constant distance from an outer surface of felt-like covering 66. In other implementations, similar results may be achieved by maintaining the same rib height, but having a distance between the outer surface of first and second agitator elements 22, 24 and the surface from which the ribs extend reduce nearer side openings 36. Any suitable combination of such approaches may also be employed.

[0076] Optionally, the pressure placed by the ribs 60 onto the agitator elements can be varied along the ribs' length.

[0077] Varying the depth that the ribs dig into the felt-like covering, and/or increasing the pressure closer to the first ends 26a, 26b, may improve the way in which hair is moved along the agitator elements. Without wishing to be bound by any particular theory, the applicant believes this may be due to the agitator elements requiring greater rib depth/pressure where its radius is smaller, and the fact that such increased depth/pressure is more achievable as the radius reduces along the agitator elements' lengths, due to the reduced torque needed.

[0078] The ribs 60 are axially (relative to the axis of rotation of the agitator elements 22, 24) spaced apart along the inside surface of cover elements 56, 58. To ensure that hair is passed from rib to rib when the cleaner head 20 is in user, ends of axially adjacent ribs 60 overlap axially with each other. As shown in FIG. 6, except for the outermost ribs, one end of each rib overlaps with the other end of an adjacent rib, as indicated by dotted lines 72, which are perpendicular to the axis of the corresponding agitator element 22. This ensures that, in use, hair picked up by the agitator elements 22, 24 is moved axially from rib to rib as the agitator elements 22, 24 rotate.

[0079] In use, a user turns on vacuum cleaner 2. A motor and impeller (not shown) cause air to be drawn through the suction chamber and outlet 34, then through wand 6 and separating system 10, in a manner known to the skilled person. At the same time, motor 38 drives first and second agitator elements 22, 24 in the direction indicated by arrows 74 and 76 in FIG. 10. The rotating agitator elements 22, 24 agitate the surface of the floor with which they are in contact. This agitation helps lift material such as hair, dust, and dirt off the floor, thereby increasing the amount of such material that is sucked into vacuum cleaner 2 for capture within separating system 10.

[0080] As best shown in FIG. 10, hair 90 that is picked up by one of agitator elements 22, 24 will encounter a contact face 68 of at least one of the ribs 60 as the agitator element 22, 24 rotates within its corresponding cover element 56, 58. Contact face 68 of rib 60 catches the hair 90 and scrapes it relative to the felt-like covering 66. The angle made by ribs 60 as a result of its spiral path tends to urge the hair 90 axially along a surface of the agitator element 22, 24 towards the first end 26a, 26b, as the agitator element 22, 24 rotates relative to its corresponding cover element 56, 58.

[0081] Angle y of the contact face 68 tends to encourage the hair 90 to be lifted away from (or at least not dug further into) the felt-like covering 66.

[0082] Due to the first end 26a, 26b being free (i.e., due to the cantilevered nature of the agitator element mounting), hair 90 that is moved along the agitator element 22, 24 can be pulled off the agitator element 22, 24 by the user while the vacuum cleaner is turned off. Optionally, and as shown in the implementation of FIGS. 4-9, the outermost rib 60 extends to the outer end of the cover elements 56, 58 adjacent the respective first ends 26a, 26b. This results in any hair 90 captured by ribs 60 being ejected from between the cover element 56, 58 and the corresponding agitator element 22, 24, where it may be more easily removed by the user.

[0083] Depending upon the particular configuration, the hair 90 may actually be pushed completely off the first end 26a, 26b by the action of the outermost rib against the agitator element 22, 24, without user interaction.

[0084] Especially where the captured hair is long, or there are several strands, the hair may be tangled and/or rolled into a complete or partial loop of hair as it is moved axially along the agitator 22, 24 by the corresponding ribs 60. This loop can be picked up by the user and discarded, or the user can attempt to vacuum it up with vacuum cleaner 2.

[0085] The ribs 60 moving hair in the direction of the first end 26a, 26b in this manner tends to reduce the amount of hair tangled around the agitator element as well as simplifying removal of hair.

[0086] The implementation of FIGS. 4-9 includes six ribs 60 per cover element 56, 58. The skilled person will appreciate, however, that the particular number of ribs, and their shape, length, angle, cross-section, and configuration may be varied to suit particular implementations.

[0087] For example, FIG. 11 shows an implementation in which only a single rib 60 is used for each of the cover elements 56, 58. To ensure hair can be picked up along the full length of the agitator elements 22, 24, rib 60 extends the full width of the cover elements 56, 58. This results in the rib 60 making a relative shallow angle (relative to an axis of the agitator elements) with respect to the felt-like covering 66 of the agitator elements 22, 24. This may reduce the efficiency with which hair is moved along by the rib 60, but overall performance is also affected by several other factors, including the length of the agitator element, the circumferential extent of the cover element (and hence the potential maximum length of the ribs), the pressure of the ribs on their respective agitator elements, and other factors that will be understood by the skilled person.

[0088] FIG. 12 shows an implementation in which three ribs 60 are used for each of the cover elements 56, 58. As with the implementation of FIGS. 4-9, the ends of adjacent ribs 60 overlap axially with each other. It will be noted that rib 60 makes a steeper angle with respect to the felt-like covering 66 of the agitator elements 22, 24, as compared with the ribs 60 of FIG. 11.

[0089] FIG. 13 shows an implementation in which six ribs 60 are used for each of the cover element 56, 58. As with the implementation of FIGS. 4-9, the ends of adjacent ribs 60 overlap axially with each other. It will be noted that rib 60 makes an even steeper angle with respect to the felt-like covering 66 of the agitator elements 22, 24 than the ribs of FIG. 12. In addition, the spacing of ribs 60 in the particular implementation of FIG. 13 reduces as the ribs get closer to side opening 36. This has an effect similar to that of increasing the depth/pressure of rib 60 on the felt-like covering 66. The skilled person will appreciate that, where variable spacing is used, there may be an increased overlap between adjacent ribs when they are closer together.

[0090] Although the ribs 60 in the previously described implementations generally take a spiral path, the skilled person will appreciate that other angled paths that are not mathematically spirals may also be used. For example, the path of one or more of ribs 60 can maintain a constant angle relative to, for example, an axis of the corresponding agitator element, or the angle can vary along some or all of the rib's length. For example, a contact face of one or more of the ribs can start at a first angle, and have that angle increase along the rib's length. This causes the hair to be moved faster as it moves along the rib. This arrangement may at least partly account for the reduced axial distance traversed by each rib as the circumference of the agitator element decreases. An example of an implementation in which the rib angles change along their lengths is shown in FIG. 14.

[0091] In some implementations, the or each rib traces a helix of a single, constant axial pitch along the length of the housing. One advantage that this may offer is if the cover element is manufactured by moulding, and the ribs are part of the moulded cover element. The cover element can be removed from the mould element by rotating the mould element and the cover element relative to each other.

[0092] For example, FIG. 15 schematically shows an example of a cover element 80 having ribs 82. The paths of ribs 82 in FIG. 15 are artificially extended to illustrate the principle. The ribs 82 trace a helix of a single, constant axial pitch. The ribs 82 are spaced axially from each other by a constant distance, as indicated by arrows 84, but can have different spacings in other implementations. As shown schematically in FIG. 16, an inner mould element 86 and the cover element 80 can effectively be unscrewed from each other after moulding is complete.

[0093] While the ribs 60, 82 are shown as being moulded as part of their respective cover elements 56, 58, 80, the skilled person will appreciate that the ribs can be provided in any other suitable manner. For example, they can be over-moulded with their cover element, or mechanically and/or adhesively attached to their cover element. The or each cover element can be machined to form the ribs. An additive manufacturing process can be used to form the ribs onto the cover element, or to produce the cover element and ribs together.

[0094] Although various implementations show each agitator with a separate cover, the skilled person will appreciate that a single cover can include ribs for more than one agitator element. Also, the ribs may be provided on or in any suitable part of the housing. For example, instead of being formed on a cover element, the ribs may be at least partly formed on an inner surface of the housing that does not form part of a separate cover element.

[0095] Although the described implementations use a pair of agitator elements 22, 24 and corresponding cover elements 56, 58, the skilled person will appreciate that the number of agitator elements may be greater or less than this. For example, a single agitator element may be used.

[0096] Alternatively, two or more pairs of agitator elements may be used, which may or may not be the same as each other.

[0097] Also, the described implementations use tapered (i.e., frusto-conical) agitator elements 22, 24. However, the skilled person will appreciate that the cross-sectional shape of the agitator element(s) may take any other suitable form. For example, the or each agitator element may be cylindrical, barrel-shaped, or may vary in cross-sectional diameter along its length in any other manner. That said, the use of tapered agitator elements has the added advantage of encouraging release of hair from the outer surface of the agitator elements, due to the reducing diameter as the hair is moved along the agitator elements by the ribs.

[0098] The or each rib may optionally be in continuous contact with the outer surface of its corresponding agitator element along substantially the full length of the rib, except for any ramp in and/or ramp out portion at either end of the rib.

[0099] Where terms such as spiral and helical are used, the skilled person will appreciate that these refer to a general shape rather than any strict mathematical definition associated with such terms.

[0100] For example, the angle of the or each rib can follow any suitable angular path within housing 32, including a path over which the angle changes, while still being generally spiral or helical.

[0101] Where in the foregoing description, integers or elements are mentioned that have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the present disclosure that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some implementations of the present disclosure, may not be desirable, and may therefore be absent, in other implementations.