CLEANER HEAD FOR A VACUUM CLEANER

FIELD OF THE INVENTION

The present invention relates to a cleaner head for a vacuum cleaner.

BACKGROUND OF THE INVENTION

Efforts are continually being sought to improve the pickup performance of vacuum cleaners.

SUMMARY OF THE INVENTION

The present invention provides a cleaner head for a vacuum cleaner comprising: a main body having a suction chamber; and a roller rotatably mounted to the main body at a location forward or rearward of the suction chamber, wherein the roller is configured to rotate in a first direction when the cleaner head is manoeuvred over a cleaning surface in one of a forward direction and a rearward direction, and is prevented from rotating in a second opposite direction when the cleaner head is manoeuvred over the cleaning surface in the other of the forward direction and the rearward direction.

When mounted forward of the suction opening, the roller is configured to rotate when the cleaner head is manoeuvred in a forward direction over the cleaning surface. Consequently, when the cleaner head comes upon relatively large dirt during forward travel, the dirt is permitted to pass beneath the rotating roller and into the suction chamber. This then reduces snowploughing of large dirt. When the cleaner head is manoeuvred in a rearward direction, the roller is prevented from rotating. Consequently, dirt within the suction chamber is hindered from escaping beneath the now static roller. The dwell time of dirt within the suction chamber therefore increases and thus more of the dirt may be drawn up into the vacuum cleaner.

When mounted rearward of the suction opening, the opposite behaviour is observed. In particular, the roller is configured to rotate when the cleaner head is manoeuvred in a rearward direction, and is static when the cleaner head is manoeuvred in a forward direction. As a result, snowploughing of large dirt may be reduced during rearward travel of the cleaner head, and dirt within the suction chamber may be hindered from escaping during forward travel.

By reducing snowploughing of dirt in one direction of travel whilst hindering the escape of dirt in the opposite direction of travel, the pickup performance of the cleaner head may be improved.

Many conventional cleaner heads focus on improving pickup performance during forward travel only. In some examples, the cleaner head may comprise a strip of plastic, rubber or plush fibres located rearward of the suction chamber. During use, the strip contacts and forms a seal with the cleaning surface. This then ensures that dirt within the suction chamber is hindered from escaping during forward travel of the cleaner head. However, a disadvantage with this arrangement is that the strip snowploughs dirt during rearward travel.

With the cleaner head of the present invention, improved pickup performance may be achieved during rearward travel (e.g., by locating the roller rearward of the suction chamber) without significantly impacting pickup performance during forward travel. As a result, the overall pickup performance of the cleaner head may be improved.

The roller may create a restriction or seal with the cleaning surface. As a result, the pressure within the suction chamber may be improved, which in turn may improve pickup performance. By contrast, if a significant gap were to exist between the roller and the cleaning surface, air would be drawn beneath the roller and into the suction chamber, thereby compromising the negative pressure within the suction chamber.

The roller may comprise an elongate body covered with a compressible material. In examples, the elongate body may be covered with a plush of fibres. In other examples, the elongate body may be covered with a solid foam (such as a closed-cell foam), felt, non-woven or the like. In some examples, the compressible material may comprise a composite of a compressible core (e.g., formed of foam, felt, non-woven, etc.) surrounded by a flexible outer sleeve (e.g., formed of rubber). By covering the body with a compressible material, a relatively good restriction or seal may be achieved between the roller and the cleaning surface. Relatively large dirt is nevertheless able to pass beneath the rotating roller without adversely affecting the pressure within the suction chamber.

The roller may be configured to move vertically relative to the main body between a lower position and an upper position, and the roller may be biased to the lower position. In examples, the roller may be pivotally mounted to the main body such that the roller pivots between the lower position and the upper position. By configuring the roller such that it is free to move vertically, a relatively good restriction or seal may be achieved between the roller and the cleaning surface. Upon contacting large dirt, the roller may move vertically to enable the dirt to pass beneath the roller. As a result, snowploughing of dirt may be reduced without adversely affecting the pressure within the suction chamber. Furthermore, by biasing the roller to the lower position, a good negative pressure may be maintained within the suction chamber in the absence of large dirt or when the roller is static.

The suction chamber may be delimited by the roller. As a result, relatively large dirt may pass beneath the roller and immediately into the suction chamber, thus improving dirt pickup. Moreover, the roller may provide an effective seal or restriction with the cleaning surface along one side of suction chamber, and thus a good negative pressure may be achieved within the suction chamber.

The cleaner head may comprise an agitator rotatably mounted to the main body and a drive assembly for driving the agitator, and the agitator may rotate independently of the roller. In examples, the agitator may comprise a brushbar having tufts or strips of bristles and/or the drive assembly may comprise an electric motor and a transmission for transmitting torque generated by the electric motor to the agitator. The agitator may agitate dirt on the cleaning surface and thus improve dirt pickup. For example, the agitator may comprise shorter, stiffer bristles for agitating dirt from carpeted surfaces and/or longer, more flexible bristles to agitate or sweep dirt from hard surfaces, such as wooden or tiled surfaces. The agitator rotates independently of the roller. As a result, the speed of agitator is not dependent on the speed at which the roller rotates or the speed at which the cleaner head is manoeuvred over the cleaning surface.

The agitator may be driven by the drive assembly (and therefore rotate) when the cleaner head is manoeuvred over the cleaning surface in both the forward direction and the rearward direction. This then has the advantage that dirt may be agitated from the cleaning surface during both forward and rearward travel of the cleaner head.

The roller may be located rearward of the agitator. During use, a user will typically focus on the forward travel of the cleaner head. By locating the roller rearward of the agitator, the cleaner head may be provided with features at the front of the cleaner head that prioritise dirt pickup during forward travel. For example, the front of the main body may comprise slots or openings through which large dirt may enter the suction chamber during forward travel. Such slots might normally compromise the pressure within the suction chamber, resulting in a drop in pickup performance. However, the roller may be used to create a restriction or seal at the rear of the suction chamber and thus a good negative pressure may be achieved within the suction chamber despite the slots in the front of the main body.

A diameter of the agitator may be greater than that of the roller. Moreover, the diameter of the agitator may be at least twice that of the roller. Having a relatively large agitator has the advantage that dirt may be agitated from the cleaning surface at a lower peak electrical power. For example, the agitator may comprise a brushbar having one or more strips of bristles that are arranged helically about the brushbar. As the diameter of the agitator increases, the number of bristles in contact with the cleaning surface at any one time decreases. As a result, the peak electrical power required to drive the agitator may be reduced. A further advantage of having a larger agitator is that the drive assembly may be housed within the agitator. Additionally, wrapping of hair and fibres around the agitator may be reduced. By contrast, the roller is not intended to agitate the cleaning surface. Accordingly, by employed a small diameter roller, the cost, weight and/or size of the cleaner head may be reduced.

The roller may be mounted to the main body by a clutch bearing. This then provides a relatively convenient means for ensuring that the roller is free to rotate in the first direction, but is prevented from rotating in the second direction.

The outer surface of the roller may have a relatively low coefficient of friction. For example, the roller may be covered in a plush of fibres. This then has the advantage that, when the roller is prevented from rotating, the roller does not generate excessive resistance and/or noise. However, when the cleaner head is manoeuvred over hard surfaces, such as wooden or tiled surfaces, the roller may fail to rotate or rotate poorly. This may then lead to increased snowploughing of dirt. Accordingly, the cleaner head may comprise a wheel mounted to the main body. The wheel is then free to rotate relative to the main body in the first direction and the second direction, and the roller is mounted to the wheel by a clutch bearing. When the cleaner head is placed onto the cleaning surface, the wheel contacts the cleaning surface and rotates in both directions as the cleaner head is manoeuvred forwards and rearwards. The roller is mounted to the wheel by a clutch bearing.

When the wheel rotates in the first direction, the clutch bearing engages and transmits torque from the wheel to the roller. As a result, the roller moves together with the wheel in the first direction. Conversely, when the wheel rotates in the second direction, the clutch bearing disengages and no torque is transmitted from the wheel to the roller. Accordingly, in the absence of any forces acting on the roller, the roller is static.

When the arrangement described in the preceding paragraph is used on a carpeted surface, the wheel may sink into the cleaning surface. The resulting friction between the roller and the cleaning surface may then be sufficient to cause the roller to rotate in the second direction when the clutch bearing is disengaged. Accordingly, the roller may be mounted at a first end to the main body by a first clutch bearing, and the roller may be mounted at a second end to the wheel by a second clutch bearing. The first clutch bearing then engages when the roller attempts to rotate in the second direction. As a result, the roller is prevented from rotating in the second direction. The second clutch bearing, on the other hand, engages when the wheel rotates in the first direction. As a result, the roller is also caused to rotate in the first direction.

The present invention also provides a vacuum cleaner comprising a cleaner head as described in any one of the preceding paragraphs.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is an isometric view of a vacuum cleaner;

FIG. 2 is a front isometric view of a cleaner head of the vacuum cleaner;

FIG. 3 is a rear isometric view of the cleaner head;

FIG. 4 is an underside view of the cleaner head;

FIG. 5 is a side view of the cleaner head;

FIG. 6 is a sectional slice through the cleaner head in the plane A-A indicated in FIG. 4; and

FIG. 7 is a section through the cleaner head in the plane B-B indicated in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The vacuum cleaner 10 of FIG. 1 comprises a handheld unit 20 attached to a cleaner head 40 by means of a wand or tubular duct 30.

The handheld unit 20 comprises a vacuum motor (not shown) and a dirt separator 22. During use, the vacuum motor generates suction at the cleaner head 40, causing dirt-laden air to be drawn in through the cleaner head 40. From there, the dirt-laden air is carried to the dirt separator 22 via the wand 30. Dirt is then separated from the dirt-laden air and the cleansed air is expelled from the handheld unit 20.

Referring now to FIGS. 2 to 7, the cleaner head 40 comprises a head unit 50 and a neck 100.

The head unit 50 comprises a main body 60, an agitator assembly 70, and a roller assembly 80.

The main body 60 comprises a suction chamber 61, a plurality of inlets 62,63,64, and an outlet 65. During use, dirt-laden air is drawn in through the inlets 62,63,64 and into the suction chamber 61. From there, the dirt-laden air is drawn out through the outlet 64. In this example, the inlets comprise a suction opening 62 provided on the underside of the main body 60, side bleeds 63 provided on the sides of the main body 60, and debris slots 64 provided in the front of main body 60.

The main body 60 further comprises gates 66 that can be raised and lowered to open and close the debris slots 64, and an actuator 67 that is moveable to raise and lower the gates 66. In this example, the actuator 67 takes the form of a mechanical slider that can be moved to the right or left in order to open or close the gates 66. When the gates 66 are raised and the debris slots 64 are open, large dirt is able to pass through the slots 64 and into the suction chamber 61. As a result, snowploughing of dirt during forward travel of the cleaner head 40 may be reduced. However, owing to size of the debris slots 64, a loss of negative pressure within the suction chamber 61 arises, which may reduce pickup performance. When the gates 66 are lowered and the debris slots 64 are closed, a gain in negative pressure occurs within the suction chamber 61 and thus pickup performance may be improved. However, snowploughing of large dirt during forward travel may increase.

The agitator assembly 70 comprises an agitator 71 and a drive assembly 72.

The agitator 71 is rotatably mounted to the main body 60 within the suction chamber 61. In this example, the agitator 71 takes the form of a brushbar and comprises a cylindrical body 73, and a plurality of bristle strips 74,75 arranged helically about the body 73. The bristle strips 74,75 comprise a first strip of bristles 74 and a second strip of bristles 75. The first strip 74 and the second strip 75 are intended to agitate dirt from different surface types. The first bristles 74 are stiffer and shorter, and are intended to agitate dirt from carpeted surfaces. The second bristles 75 are longer and more flexible, and are intended to agitate or sweep dirt from hard surfaces, such as wooden or tiled surfaces.

The drive assembly 72 is responsible for driving the agitator 71 (i.e., causing the agitator 71 to rotate within the suction chamber 61). In this particular example, the drive assembly 72 is located inside the agitator 71 and comprises an electric motor and a transmission for transmitting torque generated by the electric motor to the agitator 71. In other examples, the drive assembly 72 may be located outside the agitator 71. Moreover, rather than an electric motor, the drive assembly 72 may comprise alternative means, such as an air turbine, for generating the torque necessary to drive the agitator 71.

The roller assembly 80 is rotatably mounted to the main body 60 at a location rearward of the suction chamber 61, and thus rearward of the agitator 71. In this particular example, the roller assembly 80 delimits the rear of the suction chamber 61. That is to say that the suction chamber 61 is defined in part by the roller assembly 80.

The roller assembly 80 comprises a roller 81 and a pair of wheels 82,83. The roller 81 comprises an elongate body 84 covered with a compressible material 85. In this example, the roller 81 comprises a cylindrical body covered with a plush of fibres. In other examples, the body 84 may be covered with a solid foam (such as a closed-cell foam), felt, non-woven or the like. In some examples, the compressible material 85 may comprise a composite of a compressible core (e.g., formed of foam, felt, non-woven etc.) surrounded by a flexible outer sleeve (e.g., formed of rubber). The wheels 82,84 are located on opposite sides of the roller 81 and have a similar outer diameter to that of the roller 81.

The main body 60 comprises a first axle 68 to which a first end of the roller assembly 80 is rotatably mounted. More particularly, a first of the wheels 82 is rotatably mounted to the first axle 68 by means of a plain bearing, and a first end of the roller 81 is rotatably mounted to the first axle 68 by means of a first clutch bearing 91 (i.e., a one-way bearing). The roller assembly 80 comprises a second axle 88 that extends outwardly from a second end of the roller assembly 80. A second of the wheels 83 is rotatable mounted to the second axle 88 by means of a second clutch bearing 92, and the roller 81 is fixedly mounted to the second axle 88. The second axle 88 is then rotatably mounted to the main body 60 by means of a plain bearing.

The first clutch bearing 91 ensures that the roller 81 is permitted to rotate relative to the main body 60 in one direction only. More particularly, the first clutch bearing 91 ensures that the roller 81 is permitted to rotate relative to the main body 60 in a first direction and is prevented from rotating relative to the main body 60 in a second, opposite direction. With reference to the example shown in FIG. 6, the roller 81 is permitted to rotate in a clockwise direction, and is prevented from rotating in a counterclockwise direction. The first clutch bearing 91 therefore engages with the first axle 68 when the roller 81 rotates relative to the first axle 68 in the second direction (counterclockwise in FIG. 6). Since the first axle 68 is static and forms part of the main body 60, the engagement of the first clutch bearing 91 prevents the roller 81 from rotating relative to the main body 60 in the second direction. Conversely, the first clutch bearing 91 disengages with the first axle 68 when the roller 81 rotates in the first direction (clockwise in FIG. 6). As a result, the roller 81 is free to rotate relative to the main body 60 in the first direction.

The second clutch bearing 92 ensures that the second wheel 83 is permitted to rotate relative to the roller 81 in the second direction and is prevented from rotating relative to the roller 81 in the first direction. When the second wheel 83 rotates in the first direction (clockwise in FIG. 6), the second clutch bearing 92 engages with the second axle 88. Since the second axle 88 is fixed to the roller 81, the roller 81 is also caused to rotate. The second clutch bearing 92 therefore transmits torque from the second wheel 83 to the roller 81. As a result, the second wheel 83 and the roller 81 move together in the first direction. Conversely, when the second wheel 83 rotates in the second direction (counterclockwise in FIG. 6), the second clutch bearing 92 disengages from the second axle 88. The second wheel 83 is therefore free to rotate relative to the roller 81 in the second direction. Accordingly, even when the roller 81 is prevented from rotating relative to the main body 60 by virtue of the first clutch bearing 91, the second wheel 83 is nevertheless free to rotate relative to the main body 60 in the second direction by virtue of the second clutch bearing 92.

The roller assembly 80 is mounted to the main body 60 such that the roller assembly 80 is free to move vertically relative to the main body 60. In particular, the roller assembly 80 is free to move vertically between a lower position and an upper position. The roller assembly 80 is then biased to the lower position. In the present example, the main body 60 comprises a housing 93 and a pair of support arms 94 that are mounted to the housing 93 so as to pivot about pivot axis 95. The roller assembly 80 is then mounted to the support arms 94 in the manner described above. The main body 60 further comprises a pair of torsion springs (not shown), each of which biases a respective support arm 94 into the lower position. In the present example, vertical movement of the roller assembly 80 is achieved by pivoting. In other examples, the roller assembly 80 may translate (i.e., move linearly) up and down.

The neck 100 is rotatably attached to the head unit 50 at one end and is removably attached to the wand 30 of the vacuum cleaner 10 at the opposite end. In this example, the neck 100 is articulated and comprises a forward portion 101 that is rotatably attached to the main body 60 of the head unit 50, and a rearward portion 102 that is pivotally attached to the forward portion 101. The neck 100 further comprises a pair of dome-shaped wheels 103 that are rotatably attached to the forward portion 101, and which converge beneath the forward portion 101.

During use, the cleaner head 40 is manoeuvred over a cleaning surface by manipulation of the wand 30. For example, the cleaner head 40 may be manoeuvred forwards and rearwards by pushing and pulling on the wand 30. Additionally, the cleaner head 40 may be steered to the left and right by twisting the wand 30. The articulation in the neck 100 and the rotatable connection between the neck 100 and the head unit 50 help ensure that, as the cleaner head 40 is manoeuvred over the cleaning surface, the head unit 50 maintains a level profile with the cleaning surface. The wheels 103 act to support the neck 100 and help prevent the head unit 50 from lifting off the cleaning surface, particularly when a push force is applied to the wand 30.

As the cleaner head 40 is manoeuvred forwards and rearwards, the agitator 71 rotates to agitate dirt from the cleaning surface. The agitated dirt is then entrained by the moving air drawn into the suction chamber 61. The wheels 82,83 of the roller assembly 80 are in contact with the cleaning surface and rotate during both forward and rearward travel of the cleaner head 40. However, as will now be explained, the roller 81 of the roller assembly 80 rotates during rearward travel only of the cleaner head 40.

During forward travel of the cleaner head 40, the first clutch bearing 91 prevents the roller 81 from rotating relative to the main body 60 in the second direction (counterclockwise in FIG. 6). The roller 81 does not therefore rotate as the cleaner head 40 is manoeuvred forwards over the cleaning surface. This then has the advantage that dirt within the suction chamber 81 is hindered from escaping beneath the roller 81. The dwell time of dirt within the suction chamber 61 therefore increases and thus more of the dirt may be entrained by the air moving through the suction chamber 61. By contrast, if the roller 81 were to rotate during forward travel of the cleaner head 40, dirt within the suction chamber 61 may pass beneath the rotating roller 81. Indeed, the roller 81 may actively push dirt out the rear of the cleaner head 40.

During rearward travel of the cleaner head 40, the first clutch bearing 91 disengages and thus the roller 81 is free to rotate relative to the main body 60. Additionally, the second clutch engages 92 and thus the roller 81 rotates together with the second wheel 83 in the first direction (clockwise in FIG. 6). The roller 81 therefore rotates as the cleaner head 40 is manoeuvred rearwards over the cleaning surface. Consequently, when the cleaner head 40 comes upon large dirt during rearward travel, the dirt is permitted to pass beneath the rotating roller 81 and into the suction chamber 61. This then reduces snowploughing of large dirt.

The roller 81 extends substantially across the width of the suction chamber 61. Additionally, the roller 81 creates a restriction or seal with the cleaning surface. As a result, a good negative pressure may be achieved within the suction chamber 61, which in turn may improve pickup performance. By contrast, if a significant gap were to exist between the roller 81 and the cleaning surface, significant airflow would be drawn beneath the roller 81 and into the suction chamber 61, thereby compromising the pressure within the suction chamber 61. By ensuring that the roller 81 forms a restriction or seal with the cleaning surface, improved pickup may be achieved during rearward travel without adversely compromising the pressure within suction chamber 61. As a result, a net improvement in pickup performance may be achieved.

In the present example, the suction chamber 61 is delimited by the roller 81. As a result, relatively large dirt may pass beneath the roller 81 and immediately into the suction chamber 61, thus improving dirt pickup. Moreover, the roller 81 may provide an effective restriction or seal with the cleaning surface along one side of suction chamber 61, and thus a good negative pressure may be achieved within the suction chamber 61. Nevertheless, in other examples, the roller 81 may be spaced from the suction chamber 61.

The roller 81 comprises a body 84 covered with a compressible material 85, such as a plush of fibres, closed-cell foam, felt or the like. By covering the body 84 with a compressible material 85, dirt may pass beneath the rotating roller 81 whilst maintaining a relatively good restriction or seal with the cleaning surface.

The roller assembly 80 is free to move vertically relative to the main body 60. Consequently, upon contact with particularly large dirt, the roller 81 may move upwards to enable the dirt to pass beneath the roller 81. After the dirt has passed beneath the roller 81, the roller assembly 80 is biased downwards such that the restriction or seal is again established between the roller 81 and the cleaning surface. As a result, snowploughing of dirt during rearward travel may be further reduced without adversely affecting the pressure within the suction chamber 61. In spite of the aforementioned advantages, the roller assembly 80 may be mounted to the main body 60 in a manner that does not permit vertical movement.

The roller 81 is prevented from rotating relative to the main body 60 by the first clutch bearing 91. A clutch bearing provides a relatively convenient means for ensuring that the roller 81 is free to rotate in the first direction, but is prevented from rotating in the second direction. Whilst convenient, clutch bearings can be relatively expensive. Accordingly, the cleaner head 40 may comprise alternative means for ensuring that the roller 81 is permitted to rotate in the first direction and is prevented from rotating in the second direction. By way of example, the roller 81 and the main body 60 may comprise ratchet-like features that permit rotation in the first direction only. For example, the roller 81 may comprise teeth at an end of the roller, and the main body 60 may comprise a pawl that engages with the teeth to prevent rotation in the second direction. In another example, the roller assembly 80 may be mounted to the main body 60 in a manner that permits a small horizontal translation of the roller assembly 80 relative to the main body 60. When the cleaner head 40 is manoeuvred forwards over the cleaning surface, the roller assembly 80 translates rearwards relative to the main body 60, and the roller 81 engages with the main body 60 to brake the roller 81. Conversely, when the cleaner head 40 is manoeuvred rearwards over the cleaning surface, the roller assembly 80 translates forwards relative to the main body 60, and the roller 81 disengages from the main body 60 and is free to rotate.

In the example described above, the roller assembly 80 comprises a pair of wheels 82,83. Additionally, the roller 81 is mounted to one of wheels 83 by a clutch bearing 92. Conceivably, the wheels 82,83 and/or the clutch bearing 92 may be omitted. However, as will now be explained, there are advantages in employing the wheels 82,83 and the clutch bearing 92. In the present example, the roller 81 comprises a body 84 covered with a plush of soft fibres 85. As a result, the outer surface of the roller 81 has a relatively low coefficient of friction. This then has the advantage that, when the roller 81 is static during forward travel of the cleaner head 40, the roller 81 does not generate excessive resistance and/or noise. However, if the wheels 82,83 and the second clutch bearing 92 were omitted, the roller 81 may fail to rotate or may rotate poorly when the cleaner head 40 is manoeuvred rearwards over hard surfaces, such as wooden or tiled surfaces. This may then lead to increased snowploughing of dirt. By mounting the roller 81 to one of the wheels 83 by means of a clutch bearing 92, the roller 81 is caused to rotate together with the wheel 83 during rearward travel. Whilst this benefit may be achieved through the provision of a single wheel, the provision of two wheels 82,83, located on opposite sides of the roller 81, helps ensure that the roller 81 has a more consistent interference with hard cleaning surfaces. Additionally, the provision of two wheels 82,83 better guides the cleaner head 40 in a straight line during forward and rearward travel. In the example described above, only the second wheel 83 is clutched (i.e., mounted to the roller 81 by a clutch bearing 92). In other examples, both wheels 82,83 may be clutched. As a result, the roller 81 is actively driven in the first direction by both wheels 82,83. This then has the benefit that, should one of the wheels 82,83 skid on the cleaning surface, the roller 81 continues to be driven by the other of the wheels 82,83.

In spite of thee advantages noted in the preceding paragraph, one or more of the wheels 82,83 and/or the clutch bearing 92 may be omitted. Should the wheels 82,83 and/or the second clutch bearing 92 be omitted, the roller 81 may comprise features that increase the surface friction of the roller 81. For example, rather than or in addition to the plush of fibres, the roller 81 may comprise foam or felt on which dots of rubber are provided to achieve the required friction with the cleaning surface.

The cleaner head 40 comprises debris slots 64 in the front of the main body 60 that can be opened in order to admit large debris during forward travel of the cleaner head 40. As noted above, when the debris slots 64 are opened, there is a loss in the negative pressure within the suction chamber 61. Dirt entrainment and pickup may therefore be adversely affected. However, the restriction or seal created by the roller 81 at the rear of the suction chamber 61 help ensure that, in spite of the open debris slots 64, a relatively good pressure may be achieved within the suction chamber 61.

In the example described above, the cleaner head 40 comprises two very different mechanisms (debris slots 64 and a roller 81) for admitting large dirt into the suction chamber 61 during forward and rearward travel. The primary reason for this is that, during use, a user will often focus on the forward travel of the cleaner head 40. The debris slots 64 depicted in this particular example are generally more effective than the roller 81 at admitting large dirt into the suction chamber 61. However, the debris slots 64 result in a greater pressure drop within the suction chamber 61. By having debris slots 64 located in the front of the main body 60 and a roller 81 mounted at the rear, pickup of large debris may be prioritized for forward travel. Nevertheless, pickup of large debris during rearward travel is also achieved whilst maintaining a good pressure within the suction chamber 61. As a result, a net improvement in dirt pickup may be observed, particularly when user behaviour is taken into account.

The debris slots 64 at the front of the main body 60 may be omitted and the cleaner head 40 may comprise a further roller assembly, located forward of the suction chamber 61, for admitting large debris during forward travel. The further roller assembly then operates in a similar way to the roller assembly 80 located rearward of the suction chamber 61. However, in contrast to the roller 81 located rearward of the suction chamber 61, the roller located forward of the suction chamber 61 is configured to rotate when the cleaner head 40 is manoeuvred in a forward direction over the cleaning surface, and is prevented from rotating when the cleaner head 40 is manoeuvred in a rearward direction.

In further examples, the cleaner head 40 may comprise a single roller assembly located forward of the suction chamber 61, i.e., the roller assembly 80 located rearward of the suction chamber 61 may be omitted. The rear part of the main body 60 (i.e., that part rearward of the suction chamber 61) may then resemble that of a conventional cleaner head. Whilst this arrangement is likely to lead to increased snowploughing of large debris during rearward travel, the provision of a roller assembly in front of the suction chamber 61 may nevertheless have advantages. For example, in comparison to the debris slots 64, a roller assembly located forward of the suction opening may achieve better sealing with the cleaning surface and thus a higher negative pressure may be achieved within the suction chamber 61.

In the examples described above, the roller assembly 80 comprises a single roller 81 that is cylindrical in shape. In other examples, the roller assembly 80 may comprise more than one roller and/or each roller may be non-cylindrical in shape. As a result, different behaviours and profiles may be achieved. For example, the roller assembly 80 may comprise two rollers arranged in tandem. Each of the rollers may be independently moveable vertically relative to the main body. When a first roller comes into contact with large debris, the first roller may move vertically to allow the dirt to pass beneath the roller. The second roller, however, does not move vertically and maintains an effective restriction or seal with the cleaning surface. As a result, the pressure within the suction chamber 61 may be improved. In another example, the roller assembly 80 may comprise a plurality of rollers that are arranged in tandem. The rollers may then be spaced apart such that a debris slot is created between adjacent rollers. In this way, the roller assembly 80 may mimic the debris slots 64 located at the front of the main body 60. In a further example, the roller assembly 80 may comprise two or more conical-shaped rollers that are arranged in tandem such that the lowermost surfaces of the rollers are level with the cleaning surface. Hair and long fibres that might otherwise wrap around and become tangled on the rollers may then migrate to and fall off the smallest end of the rollers. In other examples, the roller 81 may comprise a non-continuous outer surface. For example, the roller 81 may comprise a central body from which a plurality of flexible paddles extend radially outward. The paddles may extend linearly or helically along the length of the body. Alternatively, the paddles may be arranged in other patterns along the length of the body. For example, the paddles may be arranged as chevrons. A roller having paddles has the potential benefit that large dirt may be captured using a roller having a smaller diameter body.

In another example the paddles may be in the form of a bristle assembly comprising a plurality of bristles or a strip of bristles (not shown). A strip of bristles provides an advantage that no streaks of dirt are left behind as the tool is swept over the cleaning surface. The bristle assembly may comprise a strip of bristles formed of nylon which has the potential benefit of additional agitation on carpeted surfaces. Alternatively, the bristle assembly may comprise a strip of bristles formed of carbon fibre. Carbon fibre allows for relatively soft and fine bristles to be used, which help reduce marking of the cleaning surface. Also, carbon fibre has good anti-static properties, which means that the bristles can be swept over the cleaning surface without charging the surface.

The cleaner head 40 comprises an agitator 71 in the form of a brushbar that is driven (i.e., rotates) during both forward travel and rearward travel. As a result, dirt may be better agitated from the cleaning surface, thereby improving pickup performance. The brushbar is larger than the roller 81, and in examples may be at least twice the diameter of the roller 81. Having a relatively large brushbar has the advantage that dirt may be agitated from the cleaning surface at a lower peak electrical power. In particular, as the diameter of the brushbar increases, the number of bristles in contact with the cleaning surface at any one time decreases. As a result, the peak electrical power required to drive the brushbar decreases. A further advantage of having a large brushbar is that the drive assembly 72 may be housed within the brushbar, as in this example. Additionally, wrapping of hair and fibres around the brushbar may be reduced. By contrast, the roller 81 is not intended to agitate the cleaning surface. Accordingly, by employed a small diameter roller, the cost, weight and/or size of the cleaner head 40 may be reduced.

In the example described above, the agitator 71 comprises a brushbar that rotates about an axis that is parallel to the cleaning surface. In other examples, the agitator 71 may take alternative forms. For example, the agitator 71 may comprise one or more discs or pads that carry bristles or other cleaning elements, and which rotate about axes normal to the cleaning surface. In further examples, the agitator may be omitted altogether, thereby reducing the cost, weight and/or size of the cleaner head 40.

Although the vacuum cleaner 10 illustrated in FIG. 1 is a stick vacuum cleaner, the cleaner head 40 may equally be used with other types of vacuum cleaner, such as canister, upright or robotic vacuum cleaners. In the examples described above, the cleaner head 40 comprises a neck 100, which helps ensure that the head unit 50 maintains a level profile with the cleaning surface as the cleaner head 40 is manoeuvred forwards and rearwards. The neck 100 is not, however, pertinent to the present invention and alternative designs of neck are possible. Moreover, the neck 100 may be omitted, particularly if the cleaner head 40 forms part of an upright or robotic vacuum cleaner.

Whilst particular examples and embodiments have thus far been described, it should be understood that these are illustrative only and that various modifications may be made without departing from the scope of the invention as defined by the claims.

CLEANER HEAD FOR A VACUUM CLEANER

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