GB2496663A

GB2496663A - Cleaner head for a vacuum cleaner

Info

Publication number: GB2496663A
Application number: GB1119946.0A
Authority: GB
Inventors: Victoria Isabelle Palmer; Henry Licming Lambourn; Spencer James Robert Arthey
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2011-11-18
Filing date: 2011-11-18
Publication date: 2013-05-22
Anticipated expiration: 2031-11-18
Also published as: US20130312216A1; GB201119946D0; GB2496663B; GB2496721B; GB201217703D0; GB2496721A; JP2013106958A; CN103120570A; WO2013072665A1; EP2779883A1

Abstract

A cleaner head for a vacuum cleaning appliance comprises a suction cavity 26 having a downwardly-directed opening 28, 30 through which debris enters the suction cavity and a thread or lint lifting strip 84 which is moveable relative to the opening 28, 30. The thread lifting strip 84 is preferably moveable towards and away from the opening 28, 30. A spring such as a torsion spring biases the thread lifting strip (104, fig 5) towards the opening 28, 30. The thread lifting strip 84 may be provided within the suction cavity 26 and a second thread lifting strip 106 may also be provided.

Description

A CLEANER HEAD

FIELD OF THE INVENTION

The present invention relates to a cleaner head for a cleaning appliance. ]n a preferred embodiment, the cleaner head is suitable for use with a vacuum cleaning appliance.

BACKGROUND OF THE INVENTION

A vacuum cleaner typically comprises a main body containing dirt and dust separating apparatus, a cleaner head connected to the main body and having a suction opening, and a motor-driven fan unit for drawing dirt-bearing air through the suction opening and thc cleaner head, and into the main body. The suction opening is directed downwardly to face the floor surface to be cleaned. The dirt-bearing air is conveyed to the separating apparatus so that dirt and dust can be separated from the air before the air is expelled to the atmosphere. The separating apparatus can take the form of a filter, a filter bag or a cyclon ic arrangement.

Vacuum cleaners generally include cylinder, or canister, cleaners, upright cleaners and hand-held cleaners. A cylinder vacuum cleaner includes a main body supported by a set of wheels which is dragged along a floor surface by a hose and wand assembly extending between the main body and the cleaner head. The cleaner head is generally rclcasably attached to the end of the wand which is remote from the main body. In use, a user pushes and pulls the wand to move the cleaner head forwards and backwards over the floor surface. An upright vacuum cleaner typically comprises a main body, a rolling assembly mounted on the main body for manoeuvring the vacuum cleaner over a floor surface to be cleaned, and a cleaner head mounted on the main body. In use, a user reclines the main body of the upright vacuum cleaner towards the floor surface, and then sequentially pushes and pulls a handle which is attached to the main body to manoeuvre the vacuum cleaner over the floor surface.

I

A cleaner head may be provided with one or more of a number of features for improving the removal of dirt, dust or other debris from a surface to be cleaned. For example, the cleaner head may be provided with a brush for sweeping debris from a hard floor surface. As another example, the cleaner head may be provided with a rotatable brush bar comprising an elongate cylindrical core bearing bristles which extend radially outward from the core. The rotation of the brush bar causes the bristles to be swept between the fibres of the carpet to be cleaned, agitating both the fibres of the carpet and any debris, such as dust particles, fibres and hairs, located on the surface of the carpet and/or between the fibres of the carpet.

It is also known to provide cleaner heads which havc a suction opening which is bounded on each side by a respective working edge for agitating the fibres of a carpeted floor surface as the cleaner head is manoeuvred over such a surface. For example, WO 2002/026097 describes a cleaner head having a bottom surface which defines a suction opening through which a dirt-bearing air flow is drawn into a suction cavity. The bottom surface has an inclined leading section extending forwardly from the suction opening, and which defines a sharp front working edge at its intersection with a front wall of the suction cavity. The bottom surface also has an inclined trailing section extending rearwardly from the suction opening, and which defines a sharp rear working edge at its intersection with a rear wall of the suction cavity. With each forward and reverse stroke of the cleaner head over a carpeted floor surface, air drawn from the atmosphere passes beneath one of these working edges of the head to enter the suction cavity.

The action of pushing the cleaner head forwardly over the floor surface causes the leading section of the bottom surface to be pushed into the fibres of the carpet, concentrating the downward force applied to the carpet on the front working edge. As the leading section moves over the fibres, the upper ends of the fibres are deflected temporarily in a forwards direction to subsequently spring back into the suction cavity.

This rapid movement of the fibres causes dirt and dust to be dislodged from between the fibres and into the suction cavity, where it becomes entrained within the air flow passing beneath the front working edge and into the suction channel.

A similar action takes place as the cleaner head is pulled rearwardly over the floor surface; pulling the cleaner head rearwardly over the floor surface causes the trailing section of the bottom surface to be pulled into the carpet fibres, concentrating the downward force on the rear working edge. As the trailing section moves over the fibres, the upper ends of the fibres are deflected temporarily in a rearward direction to subsequently spring back into the suction cavity. Dislodged dirt and dust enters the suction cavity to become entrained within the air flow passing beneath the rear working edge and into thc suction channel.

The presence of these working edges can increase significantly the efficiency with which dirt and dust is removed from between the fibres of a carpet. To improve the efficiency with which threads, hair and the like, generally referred to as "lint", are removed from the surface of a carpet, a thread lifting strip, also referred to as a thread collecting strip or a lint picker, is located on each of the leading section and the trailing section of the bottom surface, adjacent the working edge defined by that section. Each thread lifting strip is generally in the form of a pad adhered or otherwise attached to the cleaner head, and having a fibrous lower surface. The fibres of the rear thread lifting strip arc inclined in a common direction to collect lint from the carpet as the cleaner hcad is moved in a forward direction over the carpet, and to release the collected lint when the cleaner head is pulled rearwardly over the carpet. The fibres of the front thread lifting strip are aligned in the opposite direction to the fibres of the rear thread lifting strip so as to collected lint as the cleaner head is pulled rearwardly over the carpet, and to release the collected lint when the cleaner head is pushed forwardly over the carpet The collected lint tends not to be released immediately from the thread lifting strip; instead the collected lint tends to agglomerate to form a mass which is eventually released from the thread lifting strip when its surface area is sufficiently large as to cause the collccted lint to be torn from the thrcad lifting strip by the air flow passing towards the suction cavity. Depending on thc size of the agglomerated lint, it may not be abc to pass immediately into the suction cavity between thc carpct and the bottom surface of the cleaner head and so may remain on the floor surface. In this case the user may have to re-position the cleaner head over the released lint so that it can be drawn into the suction cavity.

When a thread lifting strip is located on a surface that is inclined towards the suction opening to define a working edge, that thread lifting strip can tend not to be intimate 1 0 contact with the carpet across its entire width. This can have the effect that the portion of the thread lifting strip located remote from its adjacent working edgc can be less efficient at collecting lint than the portion of the thread lifting strip which is closest to its adjacent working edge. Also, as the cleaner head is moved forwards and backwards over the floor surface by the user, the cleaner head can tend to rock forwards and backwards, alternately raising and lowering thc thrcad lifting strips relativc to thc floor surface. As the raising of a thread lifting strip tends to occur during the stroke in which that thread lifting strip is arranged to collect lint, the reduced intimacy of the contact between the raised thread lifting strip and the carpet can further reduce the efficiency of the thread lifting strip.

SUMMARY OF THE INVENTION

In a first aspect, the present invcntioll provides a cleaner head for a vacuum cleaning appliance, the cleaner head comprising a suction cavity having a downwardly-directed opening through which debris enters the cleaner head, and a thread lifting strip which is moveablc relative to the opening.

As the cleaner head is manoeuvred over a carpet a force is applied in a downwards direction to the carpet by the portions of the cleaner head that are in contact with the carpet. These portions of the cleaner head may be support members for supporting the cleaner head as it manoeuvred oyer the floor. These supports may be in the form of wheels or casters. Alternatively, or additionally, these portions may be in the form of at least one edge of the opening through which dirt and debris enters the cleaner head.

The contact between the thread lifting strip and the carpet increases the surface area of the cleaner head that is in contact with the carpet at any given moment, with the result that the downwards force applied to the fibres of the carpet by the other features of the cleaner head decreases. If the thread lifting strip were to be located in a fixed position relative to the opening, the proportion of the downwards force applied to the carpet by the thread lifting strip may become sufficiently high as to impair the agitation of the fibres of the carpet by, lbr example, the edges of the opening, through a reduction in the proportion of thc three applied to the fibres by these edges, and thereby reduce the performance of the cleaner head for removing dirt and dust trapped between the carpet fibres. In view of this, the thread lifting strip is arranged so as to be moveable relative to the opening. This can reduce the proportion of the downwardly directed force which isappliedtothecaipetbythethreadliftingstrip.

The thread lifting strip may be spaced from the suction cavity. For example, the thread lifting strip may be located in front of or behind the suction cavity. The suction cavity may be formed from a front section and a rear section fluidly connected to the front section, and the thread lifting strip may be located between these sections. The suction cavity may therefore extend about the thread lifting strip, but without the thread lifting strip being located within the suction cavity. In these cases, the thread lifting strip is moveable relative to a plane containing the opening.

In a preferred embodiment however, the thread lifting strip is located within the suction cavity. As the cleaner head is manoeuvred over a carpeted floor surface during use, the reduced air pressure within the suction cavity causes a portion of the carpet to rise into the suction cavity to produce a carpet "hill". The provision of a thread lifting strip within the suction cavity can enable the thread lifting strip to be placed in intimate contact with the carpet hill during both forwards and backwards strokes of the cleaner head over the carpet, increasing the efficiency of both the collection of lint by the thread lifting strip and the subsequent release of lint fixm the thread lifting strip. As the collected lint is released frem the thread lifting strip, it is drawn immediately into the suction cavity, that is, without having to pass beneath an edge of the opening or other feature of the lower surface of the cleaner head. In this case, the thread lifting strip is moveable towards and away fim the opening.

The cleaner head may comprise a single suction cavity The suction cavity may comprise a single section arranged to receive air from the opening and to expel air fix,m the suction cavity. Alternatively, the suction cavity may comprise a fIDnt section and a rear section each having a respective opening, with the rear section being arranged to receive air from thc front section, and to expel air from the suction cavity. In this case, the thread lifting strip may be located in either the front section or the rear section of the suction cavity.

The thread lifting strip may be connected to any surface of the cleaner head. Where the thread lifting strip is located outside of the suction cavity, the thread lifting strip may be connected to any external surfhce of the cleaner head, such as the external suthce of a body defining the suction cavity or the external surface of a hose for conveying air from an outlet of the suction cavity to an outlet of the cleaner head. Alternatively, when it is located beneath the cleaner head, but external to the suction cavity, the thread lifting strip may be connected to an intcrnal suthcc of the cleaner head.

Preferably, the thread lifting strip is connected to a surface located within the suction cavity. This surface may be part of a wall defining, at least in part, the suction cavity.

This surface may be a surface of a side wail of the suction cavity, or the surface of an upper wall of the suction cavity. The thread lifting strip may extend between two side walls of the suction cavity, whereby one end of the thread lifting strip is connected to one side wall and the other end of the thread lifting strip is connected to the other side wall. Alternatively, the thread lifting strip may be connected to a surface extending across the suction cavity. This may be in the fbrm of an internal wall or other feature located within the suction cavity.

At least part of the thread lifting strip is preferably biased towards a plane containing the opening. This can enable an intimate contact to be maintained between the thread lifting strip and the carpet with, fbr example, any variation in the distance between the upper surface of the carpet and the plane containing the opening as the cleaner head is manoeuvred over the carpet.

The thread lifting strip may be biased towards the plane of the opening during only part of the movement of the cleaner head over a floor surface. In this case, the thread lifting strip may be moved away from the plane of the opening during the other one of a fbrward stroke or a reverse stroke of the cleaner head over the floor surface. For example, a rotatable wheel may be provided on the cleaner head for engaging the floor surface. The wheel may be connected to a mechanism for moving the thread lifting strip towards or away from the plane of the opening depending on the rotational direction of the wheel as the cleaner head is manoeuvred over the floor surface.

Alternatively, the thread lifting strip may be biased towards the plane of the opening during both fbrward and reverse strokes of the cleaner head over the floor surface. The thread lifting strip may be biased towards the plane of the opening in a number of different ways. As discussed above, a thread lifting strip generally comprises an array of unidirectional fibres disposed on a backing member. This backing member may be fbrmed from resilient material, such as a metallic, plastics or rubber material. In this case, the attachment of the ends of the thread lifting strip to a surface of the cleaner head, or between two surfaces of the cleaner head, so that at least some of the fibres face the plane of the opening can result in at least those fibres of the thread lifting strip being urged towards the plane of the opening by the resilient backing member.

Alternatively, the cleaner head may comprise a resilient member, such as a spring or other elastic member, for engaging the backing member to urge the fibres of the thread lifting strip towards the plane of the opening. This resilient member may be located between the thread lifting strip and a downwardly-facing surface of the cleaner head, such as the bottom surface of the cleaner head or the upper surface of the suction cavity.

As a further alternative, the thread lifting strip may comprise a plurality of relatively moveable sections. These sections may be hingedly connected, end to end, so that at least the centrally disposed sections are urged towards the plane of the opening.

The cleaner head may comprise means for moving the thread lifting strip relative to the opening. The moving means may comprise a support on which the thread lifting strip is disposed, and which is moveable relative to the opening. The thread lifting strip may be mounted on the support, for example by using an adhesive to attach a backing member of the thread lifting strip to the support. Alternatively, the fibres of the thread lifting strip may be disposed directly on the support, for example using an adhesive. In this case, the adhesive may be considered to form the backing member of the thread lifting strip.

The support may be biased towards the plane of the opening. The support may be biased under its own weight towards the plane of the opening. Alternatively, the support may be formed from resilient material, such as a metallic, plastics or rubber material.

In a preferred embodiment, resilient means are provided for biasing the support towards the plane of the opening. The resilient means may comprise one or more resilient members, such as springs or other elastic members, for engaging the support to urge the thread lifting strip towards the plane of the opening. These resilient members may be located between the support and a downwardly-facing surface of the cleaner head, such as the bottom surface of the cleaner head or the upper surface of the suction cavity. The resilient members may be located outside of the suction cavity. For example, the support may comprise a rod, shaft or other elongate member which extends through an aperture formed in an upper wall of the suction cavity, and a resilient member, such as a tension spring, may be disposed between the end of the elongate member and the upper wall of the suction cavity to urge the support towards the opening.

Alternatively, the resilient means may be located inside the suction cavity, and disposed between the support and a surface of the suction cavity. The resilient means may be provided by one or more elastic members. Each of these elastic members maybe in the form of a spring, such as a torsion spring or a compression spring, for urging the support in a direction extending towards the opening, or a flexible connector for connecting the support to the suction cavity. This flexible connector may be integral with at least one of the support and the suction cavity.

The support is preferably connected to a wall defining, at least in part, the suction cavity. This wall may be an upper wall or a side wall of the suction cavity. The support may be conncctcd to thc wall for sliding movcmcnt rclative to, or along thc wall.

Alternatively, the support may be connected to the wall for movement towards or away from the wall. In one embodiment, the support is pivotably connected to the wall. This wall maybe a wall of the suction cavity which defines one of the front edge and the rear edge of the opening, or it may be a side wall of the suction cavity. The support is preferably pivotable about an axis extending substantially parallel to a plane within which the opening is located. The support may comprise at least one arm which extends outwardly therefrom and which is connected to the wall for movement relative thereto.

At least one of the wall and the support may be shaped to define a channel between the wall and the support so that the suction cavfty surrounds the support. For example, the lcngth of the arm(s) connecting thc support to the wall may bc selected to space the support from the wall.

One end of the resilient means may be connected to, or engage, the wall and the other end of the resilient means may be connected to, or engage, the support to urge the support towards the opening.

The thread lifting strip is preferably aligned so as to be substantially parallel to the front and rear edges of the opening. The thread lifting strip may extend partially or substantially fully across the suction cavity.

The support is preferably moveable relative to the opening between a raised position and a lowered position. A stop member is preferably provided for inhibiting movement of the stop member beyond the lowered position. The stop member may be located on the support. The stop member may be arranged to abut a surface defining, at least in part the suction cavity, or another surface located within or outside the cavity.

The thread lifting strip is preferably located within a recessed portion of the support.

The thread lifting strip is preferably connected to this recessed portion of the support using an adhesive. The recessed portion of the support preferably comprises a front edge and a rear edge, each extending towards the opening, and one of these edges of the support preferably extends downwardly beyond the other of these edges. The thread lifting strip preferably comprises an array of fibres which are inclined towards this one of the edges. This can enable lint which has accumulated on the surface of the thread lifting strip to become trapped or "pinched" between this edge and the carpet as the 1 5 cleaner head is manoeuvred over the carpet, and this can assist in the removal of the accumulated lint from the thread lifting strip.

The support is preferably biased towards a position in which said one of the edges of the support is substantially co-planar with the front and rear edges of the opening. This prevents this surface from protruding downwardly beyond the opening and so prevents the edge from being urged against a hard floor surface on which the cleaner head is located. In this position, the lower surface of the thread lifting strip is preferably substantially parallel to the opening. The stop member is preferably arranged to contact a wall of the suction cavity to inhibit movement of the support beyond this position.

This wall may be the wall to which the support is connected. This edge of the support may be substantially parallel to the front edge and the rear edge of the opening. The edge is preferably relatively sharp, and so the edge is preferably defined by an edge of a surface, in the form of either a leading or a trailing section of the lower surface of the support, which is inclined relative to the lower surface of the thread lifting strip.

A plurality of thread lifting strips may be located on the support. The thread lifting strips may be arranged end to end or in a staggered arrangement along or on the support, with the fibres of the strips being aligned in a common direction. Alternatively, the thread lifting strips may be arranged in a side by side arrangement, with the fibres of the thread lifting strips being arranged in opposing directions. In this case, one thread lifting strip may collect lint during a forward stroke of the cleaner head over a carpet, and the other thread lifting strip may collect lint during a reverse stroke of the cleaner head over the carpet. An air channel may be provided between the thread lifting strips.

As a further alternative, the cleaner head may be provided with two supports each 1 0 comprising a respective thread lifting strip.

The cleaner head preferably comprises a bottom surface defining said opening. The bottom surface preferably has a leading section extending forwardly from the front edge of the opening and a trailing section extending rearwardly from the rear edge of the opening. Each of these sections is preferably inclined relative to the plane containing the opening to define relatively sharp front and rear edges of the opening. At least one of the leading section of the bottom surface and the trailing section of the bottom surface may also comprise a thread lifting strip. This thread lifting strip preferably extends substantially the entire width of the cleaner head, and is preferably substantially parallel to the front and rear edges of the opening.

In a second aspect, the present invcntion provides a cleaner hcad for a vacuum cleaning appliance, the cleaner head comprising: a suction cavity having a downwardly-directed opening through which debris enters the suction cavity, the opening being bounded in part by a front edge and a rear edge; a support located within and moveable relative to the suction cavity; a thread lifting strip mounted on the support; and resilient means for urging the support in a direction extending towards the opening.

Features described above in connection with the first aspect of the invention are equally applicable to the second aspect of the invention, and vice versa.

BRIEF DESCRIPTIOI'4 OF THE DRAWINGS

Preferred features of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view, from above, of a cleaner head; Figure 2 is a front perspective view, from below, of the cleaner head; Figure 3 is a bottom view of the cleaner head; Figure 4 is a front portion of a side cross-section taken along line A-A in Figure 3; and Figure 5 is a front portion of a side cross-sectional view taken along line B-B in Figure 3.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1 to 3 are external views of a cleaner head 10 for a vacuum cleaning appliance.

Thc clcaner head 10 comprises a main body 12 and a pair of whccls 14 arranged to allow thc clcaner head 10 to bc manocuvred over a floor surface. Each wheel 14 is rotatably connected to a respective arm 16 extending rearwardly from the main body 12.

The cleaner head 10 further comprises a connector 18 having an open end which is connectable to a wand or hose of a vacuum cleaner.

The main body 12 comprises a lower body section 20 and an upper body section 22 extending over and around the lower body section 20. The lower body section 22 defines a suction cavity of the cleaner head 10. In use, the suction cavity faces the floor surface to be cleaned and admits dirt-bearing air from the floor surface into the cleaner head 10.

In this example though, the suction cavity compriscs a front suction cavity scction 24 and a rear suction cavity section 26. Each suction cavity section 24, 26 extends substantially fully across the lower body section 20. The front suction cavity section 24 is located towards thc front of the main body 12, and the rear suction cavity scction 26 is located towards thc rcar of the main body 12, bchind the front suction cavity scction 24. The front suction cavity section 24 has a downwardly-directed suction opening 28 through which a fir st dirt-bearing air flow enters the front suction cavity section 24, and the rear suction cavity scction 26 has a downwardly-directed suction opcning 30 through which a second dirt-bearing air flow enters the rear suction cavity section 26.

Each of the suction openings 28, 30 is defined by the boftom surface 32 of the lower body section 20. The suction opening 28 is delimited by side walls 34, 36, a relatively long front wall 38 and a relatively long rear wall 40 which each upstand from the bottom surface 32 of the lower body section 20. A front working edge 42 of the suction opening 28 is defined at the intersection between the bottom surface 32 and the front wall 38, and a rear working edge 44 of the suction opening 28 is defined at the intersection between the bottom surface 32 and the rear wall 40.

The suction opening 30 is delimited by side walls 46, 48, a relatively long front wall 50 and a relatively long rear wall 52 which each also upstand from the bottom surface 32 of the lower body section 20. A channel 54 extending through the main body 12 separates the rear wall 40 of the front suction cavity section 24 from the front wall 50 of the rear suction cavity section 26. The channel 54 is split into two portions, with the upper end of each portion of the channel 54 being open to the atmosphere. A front working edge 56 of the suction opening 30 is defined at the intersection between the bottom surface 32 and the front wall 50, and a rear working edge 58 of the suction opening 30 is defined at the intersection between the bottom surface 32 and the rear wall 52.

The working edges 42, 44, 56, 58 are substantially co-planar, located within a plane Pi, identified in Figure 4, containing the suction openings 28, 30. Each of the working edges 42, 44, 56, 58 is prcfcrably relative sharp, prcferably having a radius of curvature less than 0.5 mm. To prcvent the working cdges 42, 44, 56, 58 from scratching or otherwise marking a hard floor surface as the cleaner head 10 is manoeuvred over such a surface, the cleaner head 10 comprises surface engaging support members which serve to space the working edges 42, 44, 56, 58 from a hard floor surfacc. In this embodiment, the cleaner hcad 10 compriscs a pair of wheels 60 rotatably mounted within a pair of recesses formed in thc lower body section 20. As shown in Figure 5, the wheels 60 protrude downwardly beyond the working edges 42, 44, 56, 58 so that the lowermost extremities of thc wheels 60 are disposed beneath the working cdgcs 42, 44, 56,58.

During usc, a pressure diffcrcncc is gcncrated between thc air passing through the cleaner head 10 and the external environment. This pressure difference generates a force which acts downwardly on the cleaner head 10 towards the floor surface. When the cleaner head 10 is located on a carpeted floor surface, the wheels 60 arc pushed into thc fibrcs of the carpet under the weight of the cleaner head 10 and the force acting downwardly on the cleaner head 10. The thickness of the wheels 60 is selected so that the wheels 60 will readily sink into the carpet to bring at least the working edges 42, 44, 56, 58 of the main body 12 into contact with the fibres of the carpet. The thickness of thc wheels 60 is preferably less than 5 mm.

Thc front suction cavity section 24 is connected to the rear suction cavity section 26 by intermediate channels 62 which convey the first dirt-bearing air flow into the rear suction cavity section 26. Each channel 62 is located towards a respective side of the main body 12, and passes beneath part of the bottom surface 32 of the lower body section 20. The rear suction cavity section 26 comprises an air outlet 64 through which both the fir st and second dirt-bearing air flows are emitted from the suction cavity. The air flows pass through a flexible hose 66 supported by the wheels 14 towards the connector 18. One end portion of the hose 66 has a wide mouth that fits over and seals against the air outlet 64. The other end of the internal hose 66 has a circular cross-section and is arranged to fit over and seal against a neck 68 that, in turns, fits inside the connector 1 8. The neck 68 is connected to, preferably integral with, a second pair of arms 70 which extend towards the main body 12 of the cleaner head 10. Each arm 70 is pivotably connected towards one end thereof to a first end of a respective one of a third pair of arms 72. This provides a first articulated joint of the cleaner head 10. The second end of each of the arms 72 is pivotably connected to a respective arm 16 of the main body 12 of the cleaner head 10. This provides a second articulated joint of the cleaner head 10. The first and second joints pivot about axes that arc parallel to the plane P1. The connector 18 is arranged to rotate with respect to the neck 68 about an axis that is orthogonal to the axes of the first and second joints. The rotatable connection of the neck 68 with the connector 18 forms a third joint which allows the cleaner head 10 to movc laterally. In use, the thrcc joints allow the cleaner hcad 10 to be manipulated and steered while maintaining contact of the working edges 42, 44, 56, 58 with the carpet.

A bleed valve 74 is provided in a cavity 76 located between the lower body section 20 and the upper body section 22 of the main body 12. The cavity 76 has an upper aperture 78 open to the atmosphere and which is defined by a valve seat. The cavity 76 also has a plurality of lower apertures 80 in communication with the air outlet 64. The bleed valve 74 is biased by a spring 82 into engagement with the valve seat so that, during normal usc of the cleaner head 10, there is no air flow through the cavity 76. In the event that the suction cavity becomes blocked, for example, by fabric being drawn into one of the suction cavitys 24, 26, the pressure at the air outlet 64 will drop. When the pressure inside the suction cavity falls below a predetermined value, atmospheric pressure acting on the bleed valve 74 urges it downwardly against the force of the spring 82, thereby providing a flow path fbr atmospheric air to enter the cleaner head 10. When the blockage is removed, the air pressure at the air outlet 64 will rise, reducing the force acting on the bleed valve 74 by the atmospheric air to enable the spring 82 to urge the bleed valve 74 back against the valve seat.

A thread lifting strip support 84 is located in the rear suction cavity section 26. The support 84 is connected to the lower body section 20 of the main body 12 so that it is moveable relative to the lower body section 20, and thus relative to the rear suction cavity section 26 and its suction opening 30. In this example, the support 84 is connected to the front wall 50 of the rear suction cavity section 26. The support 84 comprises a pair of arms 86 extending outwardly fit,m a main body of the support 84, and which extend through apertures fbrmed in the front wall 50. The arms 86 are provided with recesses lbr receiving shafts 88 connected to the fit,nt wall 50. The arms 86 are connected to the front wall 50 in a snap-fit which allows the arms 86 to pivot about an axis A passing longitudinally through the shafts 88. The length of the arms 86 is selected to allow the support 84 to be spaced from the front wall 50 so that the rear suction cavity section 26 extends about the main body of the support 84.

The main body of the support 84 has a recessed portion 90 to which a first thread lifting strip 92 is attached, for example using an adhesive. The thread lifting strip 92 is in the tbrm of an elongate strip or pad, having a lower surface comprising short tufts of relatively stiff bristles or fibres. The fibres of the thread lifting strip 92 are aligned in a common direction, which in this example is inclined downwardly and away from the fixrnt wall 50 of the rear suction cavity section 26. The recessed portion 90 of the support 84 defines, with the lower surface 94 of the support 84, a ftvnt edge 96 and a rear edge 98 of the support 84. The rear edge 98 protrudes downwardly beyond the fttnt edge 96. In a lowered position L of the support, as illustrated in Figures 4 and 5, thc rcar cdgc 98 is located substantially in the plane P1 containing thc working edges 42, 44, 56, 58 of the suction openings 28, 30. The support 84 includes a stop member 100 which inhibits movement of the support 84 downwardly beyond this lowered position L. The stop member 100 is located on one of the arms 86 of the support 84, and is arranged to engage an abutment surface 102 located on the front wall 50 of the rear suction cavity 58. A similar stop member 100 may be provided on the other ann 86.

The support 84 can move upwardly flvm this lowered position L to a raised position R, illustrated with dashed lines in Figures 4 and 5, through pivoting movement of the support 84 about the axis A. The support 84 is biased towards its lowered position L by a torsion spring 104. The torsion spring 104 has a first end which engages the first wall 50, and a second end which engages part of the support 84, preferably one of the arms 86 of the support 84, to urge the support 84 towards its lowered position. A second torsion spring 104 maybe provided for engaging the other arm 86 of the support 84.

A second thread lifting strip 106 is attached to the bottom surface 32 of the lower body section 20 of the main body 12. In this example, the second thread lifting strip 106 is attached to a trailing section 108 of the bottom surface. The trailing section 108 extends rearwardly from the rear working edge 58 of the suction opening 30, and is inclined upwardly relative to the plane Pi containing the worldng edges 42, 44, 56, 58. The second thread lifting strip 106 extends substantially the entire width of the main body 12. The fibres of thc second thread lifting strip 106 arc aligned so that they are inclined towards the rear working edge 58 of the suction opening 30.

In use, the cleaner head 10 is connected to a vacuum cleaning appliance which generates a suction airflow. With the cleaner head 10 positioned on a carpeted floor surface to be cleaned, the user sequentially pushes and pulls the wand to move the cleaner head 10 forwards and backwards over the carpet. During each forward stroke of the cleaner head 10, the front working edges 42, 56 move over the fibres of the carpet in such a direction that, as the fibres pass beneath the front working edges 42, 56 they enter one of the suction cavity sections 24, 26. As these front working edges 42, 56 move over the fibres, the upper ends of the fibres are deflected in a forwards direction under the action of a downwards force applied by the front working edges 42, 56. Once the front working edges 42, 56 have moved beyond the deflected fibres, the deflected fibres spring back into one of the suction cavity sections 24, 26. This rapid movement of the fibres causes dirt and dust to be dislodged from between the fibres and into the suction cavity sections 24, 26. Dirt and dust entering the front suction cavity section 24 becomes entrained within a first air flow drawn under the front working edge 42 and into the front suction cavity section 24, whereas dirt and dust entering the rear suction cavity section 26 becomes entrained within a second air flow which passes through the channel 54 and under the front working edge 56 to enter the rear suction cavity section 26. The dirt-bearing first air flow passes through the intermediate channels 62 to join the did-bearing second air flow within the rear suction cavity section 26. The air flows leave the rear suction cavity section 26 through thc air outlet 64.

During each reverse stroke of the cleaner head 10, the rear working edges 44, 58 move over the fibres of the carpet in such a direction that, as the fibres pass beneath the rear working edges 44, 58 they enter one of the suction cavity sections 24, 26. As the rear working edges 44, 58 move over the fibres, the upper ends of the fibres are deflected in a backwards direction under the action of a downwards force applied by the rear working edges 44, 58. Once the rear working edges 44, 58 have moved over these deflected fibres, the deflected fibres spring back into one of the suction cavity sections 24, 26. This rapid movement of the fibres causcs dirt aild dust to be dislodgcd from bctwccn the fibres and into the suction cavity sections 24, 26. Dirt and dust entering the front suction cavity section 24 becomes entrained within a first air flow which passes through the channel 54 and under the rear working edge 44 to enter the front suction cavity section 24, whcreas dirt and dust entcring thc rcar suction cavity section 26 becomes entrained within a second air flow which is drawn under the rear working edge 58 and into the rear suction cavity section 26. Again, the dirt-bearing first air flow passes through the intermediate channels 62 to join the dirt-bearing second air flow within the rear suction cavity section 26. The air flows leave the rear suction cavity section 26 through the air outlet 64.

Thus, during each of the forwards and backwards strokes of the clcancr head 10 over the carpet the working edges 42, 44, 56, 58 act to dislodge did and debris from between the fibres of the carpet. During each of these strokcs, thc thrcad lifting strips 92, 106 act to remove lint, in the form of threads, hair and the like, from thc surfacc of the carpet. As discusscd above, the first thread lifting strip 92 is mounted on a support 84 located within the rear suction cavity section 26. As the cleaner head 10 is manoeuvred over the carpet, a carpet "hit!" is pulled into each of the suction cavity sections 24, 26 as a result of the reduced air pressure within those suction cavity sections 24, 26. The carpet hill drawn into the rear suction cavity section 26 engages and is placed in close contact with the fIrst thread lifting strip 92. As the support 84 is moveable relative to the rear suction cavity section 26, the force acting botwccn thc carpet and the first thread lifting strip 92 as thc cleaner hcad 10 is moved ovcr the carpet is not so great as to diminish significantly the force applied to thc carpet fibres by the working cdgcs 42, 44, 56, 58, while the action of the torsion springs 104 maintains the close contact between the carpet and the first thread lifting strip 92.

The fibres of the first thread lifting strip 92 are aligned so that, with each reverse stroke of the cleaner head 10, lint located on the carpet hill is collected on the surface of the first thread lifting strip 92. The accumulated lint can be released from the first thread lifting strip 92 with a forward stroke over the cleaner head 10, to become entrained within the air flow passing through the rear suction cavity section 26. The release of thc collcctcd lint from the first thrcad lifting strip 92 can be assisted by thc rear support edge 98; as the cleaner head 10 is moved in a forward direction the collected lint can become trapped or pinched between the rear support edge 9 and the carpet, and this can result in thc coHcctcd lint being torn from the first thread lifting strip to bccomc entrained within the air flow passing through the rear suction cavity section 26.

The fibres of the second thread lifting strip 106 are aligned so that, with each forward stroke of the cleaner head 10, lint located on the carpet directly behind the rear suction cayity section 26 can become collected on the surface of the second thread lifting strip 106. Thc accumulated lint can be released from the second thread lifting strip 106 with a rcvcrsc stroke of the cleancr head 10. This released lilt can cithcr become entrained within the second air flow passing beneath the rear working edge 58 of the rear suction cavity section 26, or remain on the surface of the carpct to be subsequently drawn into the clcancr head 10.

Claims

<claim-text>CLAIMS1. A cleaner head for a vacuum cleaning appliance, the cleaner head comprising: a suction cavity having a downwardly-directed opening through which debris enters the cleaner head; and a thread lifting strip which is moveable relative to the opening.</claim-text> <claim-text>2. A cleaner head as claimed in claim 1, wherein the thread lifting strip is moveable relative to a plane containing the opening.</claim-text> <claim-text>3. A cleaner head as claimed in claim 1 or claim 2, wherein the thread lifting strip is moveable towards and away from the opening.</claim-text> <claim-text>4. A cleaner head as daimed in any preceding claim, wherein the suction cavity extends about the thread lifting strip.</claim-text> <claim-text>5. A cleaner head as claimed in any preceding claim, wherein the thread lifting strip is located within the suction cavity.</claim-text> <claim-text>6. A cleaner head as claimed in any preceding claim, wherein the thread lifting strip is connected to a surface of a wall of the cleaner head.</claim-text> <claim-text>7. A cleaner head as claimed in claim 6, wherein the surface is located within the suction cavity.</claim-text> <claim-text>K A cleaner head as claimed in any preceding claim, wherein the thread lifting strip is biased towards a plane containing the opening.</claim-text> <claim-text>9. A cleaner head as claimed in any preceding claim, comprising means for moving the thread lifting strip relative to the opening.</claim-text> <claim-text>10. A cleaner head as claimed in claim 9, wherein the moving means comprises a support on which the thread lifting strip is disposed, and wherein the support is moveable relative to the opening.</claim-text> <claim-text>11. A cleaner head as claimed in claim 10, wherein the support is biased towards a plane containing the opening.</claim-text> <claim-text>12. A cleaner head as claimed in claim 10 or claim 11, wherein the moving means comprises resilient means for urging the support towards a plane containing the opening.</claim-text> <claim-text>13. A cleaner head as claimed in claim 12, wherein the resilient means comprises at least one torsion spring.</claim-text> <claim-text>14. A cleaner head as claimed in any of claims 10 to 13, wherein the thread lifting strip is mounted on the support.</claim-text> <claim-text>15. A cleaner head as claimed in any of claims 10 to 14, wherein the support is connected to a wall defining, at least in part, the suction cavity.</claim-text> <claim-text>16. A cleaner head as claimed in claim 15, wherein the support is pivotably connected to the wall.</claim-text> <claim-text>17. A cleaner head as claimed in claim 16, wherein the support is pivotable about an axis extending substantially parallel to a plane containing the opening.</claim-text> <claim-text>18. A cleaner head as claimed in any of claims 15 to 17, wherein the wall defines one of a front edge and a rear cdgc of the opening.</claim-text> <claim-text>19. A cleaner head as claimed in any of claims 15 to 18, wherein the support comprises at least one arm which extends outwardly therefrom and which is connected to the waH for movement relative thereto.</claim-text> <claim-text>20. A cleaner head as claimed in any of claims 10 to 19, wherein the support is moveable between a raised position and a lowered position, and the moving means comprises a stop member for inhibiting movement of the support beyond the lowered position.</claim-text> <claim-text>21. A cleaner head as claimed in claim 20, wherein the support comprises said stop member.</claim-text> <claim-text>22. A cleaner head as claimed in claim 20 or claim 21, wherein the stop member is arranged to abut a surface defining, at least in part, said suction cavity.</claim-text> <claim-text>23. A cleaner head as claimed in any of claims 20 to 22, wherein the thread lifting strip is located within a recessed portion of the support.</claim-text> <claim-text>24. A cleaner head as claimed in claim 23, wherein the recessed portion of the support comprises a front support edge and a rear support edge, and wherein the edges do not extend downwardly beyond a plane containing the opening when the support is in its lowered position.</claim-text> <claim-text>25. A cleaner head as claimed in claim 24, wherein one of the support edges protrudes further from the support than the other support edge.</claim-text> <claim-text>26. A cleaner head as claimed in any preceding claim, comprising a bottom surface defining said opening, the bottom surface having a trailing section extending rearwardly from a rear edge of the opening.</claim-text> <claim-text>27. A cleaner head as claimed in claim 26, wherein the trailing section comprises a thread lifting strip.</claim-text> <claim-text>28. A cleaner head substantially as herein described with reference to the accompanying drawings.</claim-text>