WO2021069862A1

WO2021069862A1 - Cleaner head for a vacuum cleaning appliance

Info

Publication number: WO2021069862A1
Application number: PCT/GB2020/052298
Authority: WO
Inventors: Stefan Koch
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2019-10-10
Filing date: 2020-09-23
Publication date: 2021-04-15
Anticipated expiration: 2022-04-10
Also published as: GB2588155B; GB201914650D0; CN114554921A; CN114554921B; GB2588155A

Abstract

This inventive concerns a cleaner head (10) for a vacuum cleaning appliance (2) comprising a main body (12) defining an agitator chamber (40) within which is supported a rotatable agitator assembly (42) and a suction opening (28) through which a portion of the agitator assembly (42) projects to engage a surface to be cleaned. The main body (12) comprises a front section (18) and a rear section (22). The rear section (22) defines an exhaust outlet (32) of the cleaner head (10) and the front section (18) includes a deflection plate (47) comprising a deflection surface (50a, 50b, 50c) which, in use, is impacted by dirt particles energised by the rotation of the agitator assembly (42). The deflection surface (50a, 50b, 50c) is configured to deflect the energised dirt particles in a direction upwards and over the agitator assembly (42) in a direction away from the suction opening (28) and towards the exhaust outlet (32).

Description

CLEANER HEAD FOR A VACUUM CLEANING APPLIANCE

TECHNICAL FIELD

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

BACKGROUND

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

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

Conventionally, the most effective cleaner heads incorporate some kind of powered brush bar or agitator. Examples are known in which the agitator is driven by a turbine which is actuated by the airflow through the cleaner head. Other known arrangements involve the use of an electric motor that is arranged to drive the agitator. In these known arrangements, it is usual for the motor to be coupled to the agitator by a suitable drive linkage such as a belt or gear mechanism, although it is also known for the motor to be housed within the agitator which provides a particularly space-efficient arrangement. In either example, the powered agitator serves to wipe and beat the floor surface in order to improve the capability of the cleaner head to remove dirt from that surface. A common configuration is for the agitator to carry an array of bristles that extend radially outward from the surface of the agitator. The bristles are typically relatively stiff so that they engage the floor surface aggressively as the agitator rotates, thereby serving as a means to scrape and strike the floor surface to loosen embedded particles. Other strips of material such as rubber and carbon fibre filaments may be used to provide complementary characteristics to the agitator. By way of example, US8782851 B2 describes an agitator that may be provided with a combination of relatively stiff bristles, carbon filaments and rubber strips.

A significant design challenge is to optimise the way in which air flows through the cleaner head, from where air enters its interior through the suction opening, to where air is discharged from an outlet towards the dust separator. It is known that air flow velocity is an important factor in pick-up performance since dirt particles are transported more effectively when the velocity of air moving through the tool is high. This is particularly true of high energy particles such as sand. Being small and relatively heavy, such particles tend to be ejected from the floor surface and into the interior of the cleaner head at a high velocity where they tend to bounce around the cleaner head chaotically. High air flow speeds are needed to entrain the dirt particles in the air within the cleaner head and to transport those particles out of the cleaner head towards the dust collector. At low air flow speeds, however, there is a higher likelihood that these heavy particles will be deposited back onto the floor covering. It will be appreciated, therefore, that maintaining good pick-up performance is challenging, particularly at low cleaner head air flow speeds.

Although high air flow speeds are achievable by equipping the vacuum cleaner with a powerful vacuum motor, this is generally undesirable as it means that the machine is less efficient, which is a significant drawback in battery powered vacuum cleaners where energy efficiency has a direct effect on available runtime. So, it is desirable for a cleaner head to be effective at picking up even relatively heavy dirt particles from a floor surface without the need for high air flow speeds.

It is against this background that the invention has been devised. SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a cleaner head for a vacuum cleaning appliance, the cleaner head comprising: a main body defining an agitator chamber within which is supported a rotatable agitator assembly, and a suction opening through which a portion of the agitator assembly projects to engage a surface to be cleaned, wherein the main body comprises a front section and a rear section, the rear section defining an exhaust outlet of the cleaner head; and wherein the front section includes a deflection plate comprising a deflection surface which, in use, is impacted by dirt particles energised by the rotation of the agitator assembly, and wherein the deflection surface is configured to deflect the energised dirt particles in a direction upwards and over the agitator assembly in a direction away from the suction opening and towards the exhaust outlet of the cleaner head. In this way, the initial energy of the dirt particles is used to direct them towards the exhaust outlet while avoiding any haphazard collisions, which risks the dirt particles returning to the agitator chamber through either inadvertent collisions or by failing to become entrained into the air flow through the dust channel. This not only improves the pick-up performance of the cleaner head, but also provides for a reduced air flow rate therethrough, thus lowering the energy consumption of the vacuum cleaning appliance.

Preferably, the deflection plate comprises a plurality of deflection surfaces collectively arranged to define a Fresnel reflector in cross-section. By having a plurality of deflection surfaces series, the energy of the dirt particles can be reduced using a series of sequential and directional collisions. By arranging the plurality of deflection surfaces to define a Fresnel reflector in cross-section, the dirt particles can be directed to a common point, possibly where the air flow in the cleaner head is greatest.

Preferably, the deflection plate comprises a plurality of deflection panels each of which comprises a respective deflection surface of the plurality of deflection surfaces.

Preferably, the plurality of deflection panels are arranged side-by-side in a direction substantially aligned with a longitudinal axis of the agitator assembly. This ensures that all of the dirt particles energised by the agitator assembly are directed towards the plurality of deflection panels.

Preferably, the plurality of deflection panels is arranged in an arc-like fashion. Preferably, the exhaust outlet defines an exhaust outlet axis, and one or more deflection surfaces of the plurality of deflection surfaces are angularly offset from the exhaust outlet axis by a respective offset angle. This arrangement establishes the shortest path for the dirt particles deflected from the deflection surfaces over the agitator assembly towards the exhaust outlet.

Preferably, each deflection surface of the plurality of deflection surfaces is located a respective panel distance from a point on the exhaust outlet axis, and wherein the panel distance is, for a respective deflector surface, proportional to its offset angle. This arrangement ensures that the deflection surfaces are positioned ahead of the suction opening regardless of their orientation with respect to the exhaust outlet.

Preferably, the one or more deflection surfaces of the plurality of deflection surfaces angularly offset from the exhaust outlet axis have a substantially perpendicular relation with a notional line extending from the one or more deflection surfaces to intersect the exhaust outlet axis.

Preferably, one or more deflection surface of the plurality of deflection surfaces comprises a first surface portion and a second surface portion, said surface portions being divided by a generally horizontal split line.

Preferably, the first surface portion is configured to deflect the energised dirt particles in a direction towards the second surface portion.

Preferably, the second surface portion is configured to deflect the energised dirt particles in a direction over the agitator assembly. More preferably, the second surface portion is configured to deflect the energised dirt particles deflected by the first surface portion in a direction over the agitator assembly.

Preferably, the first and/ or second surface portions have a concave profile in the vertical cross-section.

Preferably, the first and/ or second surface portions have a concave profile in the horizontal cross-section. Owing to the concavity of the deflection surfaces, the path for the dirt particles deflected thereby narrows towards a point. This arrangement avoids any deliberate interaction between the deflected dirt particles and side walls of the front section, which would dissipate the energy of the deflected dirt particles and see them retained in the front section or even returned to the agitator chamber.

Preferably, the deflection plate defines at least in part a dust channel that extends rearwardly over the agitator assembly. The dust channel establishes an air flow circuit extending from the agitator chamber to the exhaust outlet for the dirt particles.

Preferably, the dust channel includes an inlet for receiving energised dirt particles from the agitator chamber and an outlet in communication with the exhaust outlet.

Preferably, the inlet of the dust channel extends substantially across the longitudinal width of the agitator assembly. This ensures that all of the dirt particles energised by the agitator assembly are directed into the dust channel.

Preferably, the width of the dust channel tapers between the inlet and the outlet. This increases the air flow velocity towards the outlet of the dust channel.

Preferably, the main body further comprises a middle section that partly defines the dust channel.

Preferably, the front section is removable from the main body. The fact that the front section is removable from the main body enables it to be cleaned separately from the other components of the cleaner head.

Preferably, the deflection surface is pivotably attached to the main body.

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

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

FIG. 4a is a rear perspective view of a front section of the cleaner head of FIG. 1 ;

FIG. 4b is a horizontal cross-sectional view of the front section of FIG. 4a; and,

FIG. 5 is a vertical cross-sectional schematic view through the centre of the cleaner head of FIG. 1.

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

SPECIFIC DESCRIPTION

Specific embodiments of the invention will now be described in which numerous features will be discussed in detail in order to provide a thorough understanding of the inventive concept as defined in the claims. However, it will be apparent to the skilled person that the invention may be put in to effect without the specific details and that in some instances, well known methods, techniques and structures have not been described in detail in order not to obscure the invention unnecessarily. Moreover, references in the following description to “left”, “right” and any other terms having an implied orientation are not intended to be limiting, and refer only to the orientation of the features as shown in the accompanying drawings. FIG. 1 shows a vacuum cleaning appliance or vacuum cleaner 2 comprising a dirt and dust separating unit 4, a motor-driven fan unit 6 and a cleaner head 10 in accordance with an embodiment of the invention. The vacuum cleaner 2 further comprises a wand 8 connecting the dirt and dust separating unit 4 and the cleaner head 10. The motor- driven fan unit 6 draws dirt-bearing air through the cleaner head 10, from a surface to be cleaned, such as a floor surface, to the dirt and dust separating unit 4, where dirt and dust particles are separated from the dirt-bearing air and the comparatively clean air is expelled from the vacuum cleaner 2. The dirt and dust separating unit 4 shown in this example is a cyclonic separating unit, but it will be understood by the skilled person that the separating unit 4 is not material to the invention and that the cyclonic separating unit could be replaced with an alternative separating unit or a combination of different separating units. Similarly, the nature of the vacuum cleaner 2 is not material to the invention. The vacuum cleaner 2 shown in FIG. 1 is a stick vacuum cleaner, but it will be understood that the cleaner head 10 disclosed herein may be used with other types of vacuum cleaners such as, for example, upright or cylinder vacuum cleaners.

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

The main body 12 comprises a housing 16 which includes front, middle and rear sections 18, 20, 22 and a lower body plate section, or sole plate 24. The front section 18 extends rearwardly over a central part of the middle section 20, and is connected to the sole plate 24 by means of releasable fasteners (not shown) insertable through recesses formed in the sole plate 24 such that the front section 18 can be removed from the main body 12. The sole plate 24 defines a generally rectangular suction opening 28 through which, in use, dirt-bearing air is drawn into the cleaner head 10 from a surface to be cleaned, such as a floor surface. The coupling 14 comprises a conduit, supported by a rolling assembly 34 for supporting the cleaner head 10 on the floor surface. The conduit comprises a forward portion connected to an exhaust outlet 32, formed in the rear section 22 of the housing 16, and a rearward portion, pivotably connected to the forward portion. The part of the coupling 14 defining the rearward portion of the conduit comprises a fixing arrangement 36 for connecting a free end 38 of the coupling 14 to the wand 8. A rigid curved hose arrangement is held within and extends between the forward and rearward portions of the conduit.

With reference to FIG. 3, two wheels 27 are mounted within recessed portions in the bottom surface of the sole plate 24 for supporting the cleaner head 10 on the floor surface. The wheels 27 are configured to support the sole plate 24 above the floor surface when the cleaner head 10 is located on a hard floor surface, and, when the cleaner head 10 is located on a carpeted floor surface, to sink into the pile of the carpet to enable the bottom surface of the sole plate 24 to engage the fibres of the carpet. The sole plate 24 may be moveable relative to the housing 16, allowing it to ride smoothly over the carpeted floor surface during cleaning.

The internal volume of the main body 12 comprises an agitator chamber 40, which is partially defined by the middle section 20 of the housing 16 and the sole plate 24. The cleaner head 10 further comprises an agitator assembly 42 comprising a generally cylindrical body 44 mounted within the agitator chamber 40 and which is rotatable about its longitudinal axis. The cylindrical body 44 houses an electric motor and a drive mechanism, which connects the agitator assembly 42 to the electric motor for driving the cylindrical body 44 about its longitudinal axis. Such agitator drive arrangements are known, and so will not be explained in further detail. The agitator assembly 42 further comprises a plurality of agitators 46 outwardly extending from the outer radial surface of the cylindrical body 44. The agitators 46 may include one or more of a plurality of soft filaments, having tips that can flex relative to the cylindrical body 44 upon contact with the floor surface, stiff bristles or a strip of continuous material, and may be made of carbon fibre or nylon, to name two common material examples. The agitator assembly 42 is arranged so that the agitators 46 protrude through the suction opening 28 with its rotation to sweep dirt and dust particles, together with other debris (hereinafter, “dirt particles”) from both a hard floor surface and a carpeted surface into the agitator chamber 40. In this example, the electric motor and drive mechanism are arranged to rotate the agitator assembly 42 in such a direction that the agitators 46 sweep over the floor surface rearwardly, towards the rear section 22 of the housing 16. In this case, a large proportion of the dirt particles that have been energised by the rotation of the agitator assembly 42 is swept towards the rear of the agitator chamber 40 and a smaller, but still significant, proportion is forwardly flung towards the front of the agitator chamber 40. The agitator chamber 40 is in fluid communication with a dust channel 52, defined by an inner side 49 of the front section 18 of the housing 16, for receiving dirt particles that have been forwardly flung by the agitator assembly 42 towards the front of the agitator chamber 40. With reference to FIG. 4a, in the present example, the front section 18 of the housing 16 comprises a deflection plate 47, arranged to be positioned ahead of the suction opening 28 in the sole plate 24, a top panel 66, extending substantially horizontally from an upper end of the deflection plate 47, and two side walls 76, 78. The deflection plate 47 at least in part defines the dust channel 52. The top panel 66, which is generally shaped like a sector of a circle, and the two side walls 76, 78 converge to define an outlet 56, which, when the cleaner head 10 is assembled, is in fluid communication with the exhaust outlet 32 formed in the rear section 22 of the housing 16, establishing an air flow circuit through the dust channel 52 from the agitator chamber 40 to the exhaust outlet 32.

The deflection plate 47 includes a plurality of deflection panels 48, generally arranged side-by-side in a direction substantially aligned with the longitudinal axis of the agitator assembly 42. In this example, the deflection plate 47 comprises five discrete deflection panels 48, the inner surfaces of which define respective deflection surfaces, generally designated by 50a, 50b, 50c. The deflection panels 48 each comprise a first panel portion 61 and a second panel portion 62 located above the first panel portion 61 and divided thereform by a generally horizontal split line 63. Similarly, the deflection surfaces 50a, 50b, 50c each comprise a first surface portion 64, located on the inner side of the first panel portion 61, and a second surface portion 65, located on the inner side of the second panel portion 62. In general, the deflection surfaces 50a, 50b, 50c are configured, in use, to deflect dirt particles that have been forwardly flung by the agitator assembly 42 through the dust channel 52 in a direction upwards and over the agitator assembly 42 towards the outlet 56.

Wth reference to FIG. 4b, the deflection panels 48 are arranged such that the deflection surfaces 50a, 50b, 50c collectively define a Fresnel reflector in cross-section. That is, the deflection surfaces 50a, 50b, 50c, whose horizontal cross-sections, in this example, have a slightly concave profile, are arranged in an arc-like fashion in order to deflect dirt particles through the dust channel 52 directly towards the outlet 56. In this example, because it is centrally located, the outlet 56 of the dust channel 52 is aligned with a longitudinal axis 68 of the exhaust outlet 32 (hereinafter, “the exhaust outlet axis 68”). This arrangement ensures a direct fluid connection between the outlet 56 of the dust channel 52 and the region of the cleaner head 10 that, in use, experiences the largest pressure drop, and so suction force. The skilled reader will recognise, however, that is it not essential to align the outlet 56 of the dust channel 52 with the exhaust outlet axis 68, and that the outlet 56 could alternatively be positioned such that it is misaligned with respect to the exhaust outlet axis 68 whilst still maintaining a fluid connection with the exhaust outlet 32.

In cross-section, the central deflection surface 50a is orientated substantially perpendicular to the exhaust outlet axis 68, so as to deflect dirt particles over the agitator assembly 42 towards the outlet 56 along a path narrowing from the deflection surface 50a to the outlet 56, whereas the remaining deflection surfaces 50b, 50c are angularly offset from the exhaust outlet axis 68 by respective offset angles. Specifically, the deflection surfaces 50b, adjacent the central deflection surface 50a, are offset with respect to the exhaust outlet axis 68 by a first offset angle a, and the outermost deflection surfaces 50c are offset with respect to the exhaust outlet axis 68 by a second offset angle b, which is greater than the first offset angle a. In this example of the cleaner head 10, the offset angles a, b are chosen such that notional lines 72, 74, extending between the deflection surfaces 50b, 50c and a point where they intersect the exhaust outlet axis 68, have a substantially perpendicular relationship with the deflection surfaces 50b, 50c. This arrangement establishes the shortest path for the dirt particles deflected from the deflection surfaces 50b, 50c over the agitator assembly 42 toward the outlet 56. Owing to the concavity of the deflection surfaces 50b, 50c, the path for the dirt particles deflected thereby narrows towards a point 71 where the notional lines 72, 74 intersection the exhaust outlet axis 68. This arrangement avoids any deliberate interaction between the deflected dirt particles and the side walls 76, 78 of the front section 18, which would dissipate the energy of the deflected dirt particles.

The deflection surfaces 50a, 50b, 50c are located a respective panel distance from the point 71 on the exhaust outlet axis 68, measured with respect to the exhaust outlet axis 68 and the notional lines 72, 74. In the present example, the point 71 is located on the exhaust outlet axis 68 in proximity to the outlet 56. The panel distance for each deflection surface 50a, 50b, 50c is proportional to its offset angle. That is, the panel distance of the deflection surfaces 50a, 50b, 50c increases with an increasing offset angle. In the present example, therefore, the panel distance of the centrally located deflection surface 50a is a minimum as its offset angle, with respect to the exhaust outlet axis 68, is zero, but it then increases in respect of the deflection surfaces 50b, which are angled with respect to the exhaust outlet axis 68 by the first offset angle a. The panel distance further increases for the outermost deflection surfaces 50c since they are angled with respect to the exhaust outlet axis 68 by the second offset angle b, which is larger than the first offset angle a. This arrangement ensures that the deflection surfaces 50a, 50b, 50c are positioned ahead of the suction opening 28 regardless of their orientation with respect to the exhaust outlet axis 68.

With reference to FIG. 5, which shows the deflection surface 50a in the vertical cross- section, the inner side 49 of the front section 18 and an outermost side 51 of the middle section 20 of the housing 16 define the dust channel 52 comprising an inlet 54, for receiving energised dirt particles from the agitator chamber 40, and the outlet 56. As mentioned above, the outlet 56 is in fluid communication with the exhaust outlet 32 formed in the rear section 22 of the housing 16 so as to establish an air flow circuit through the dust channel 52 from the agitator chamber 40 to the exhaust outlet 32. The inlet 54 of the dust channel 52 horizontally extends substantially across the longitudinal width of the agitator assembly 42 and, in this example, is partially defined between lowers ends 58 of the deflection panels 48 and a lower end 60 of the middle section 20 of the housing 16. In other examples, the inlet 54 of the dust channel 52 may be defined, at least partially, by lower edges of the deflection surfaces 50a, 50b, 50c.

The first surface portion 64 of the deflection surface 50a has a concave profile in the vertical cross-section and generally faces the inlet 54 of the dust channel 52, and extends forwardly and upwardly from its lower edge to the horizontal split line 63. The second surface portion 65 also has a concave profile in the vertical cross-section, and generally faces back across an upper side 67 of the middle section 20, which partly defines the dust channel 52. The second surface portion 65 extends upwardly and rearwardly from the horizontal split line 63 to connect with the top panel 66 of the front section 18 of the housing 16. In this embodiment, the horizontal split line 63 defines an intersection between the first and second surface portions 64, 65, although the skilled reader will understand that the first and second surface portions 64, 65 need not necessarily intersect. Moreover, although FIG. 5 only shows deflection surface 50a in cross-section, the skilled reader will appreciate that deflection surfaces 50b, 50c are similarly arranged.

As mentioned above, the inlet 54 receives energised dirt particles that have been flung forward by the rotation of the agitator assembly 42 from the agitator chamber 40, generally designated by arrows 80 in FIG. 5. Upon entering the dust channel 52, the initial energy of the dirt particles is, in the main, too high for the dirt particles to become immediately entrained within the air flow passing through the dust channel 52. Previously, this problem was addressed by configuring the walls defining a dust channel to retain the dirt particles within the dust channel through a series of haphazard collisions, until the energy of the dirt particles has dissipated sufficiently, through impacts with the walls, to enable them to become entrained within the air flow through the dust channel. However, this risks the dirt particles returning to the agitator chamber through either inadvertent collisions or by failing to become entrained into the air flow through the dust channel. The present invention differs in that the initial energy of the dirt particles is used to direct them through the dust channel 52 towards the exhaust outlet 32 using a series of sequential purposeful collisions with the deflection surfaces 50a, 50b, 50c, while avoiding any haphazard collisions. Specifically, each deflection surface 50a, 50b, 50c is configured such that an energised dirt particle is guided through the dust channel 52 to the exhaust outlet 32 by a first collision with a first surface portion 64 and a second collision with a second surface portion 65.

Upon entering the dust channel 52 through the inlet 54 from the agitator chamber 40, the energised dirt particles will tend first to impact the first panel portion 61. The concavity of the first surface portion 64 is such that the first panel portion 61 deflects substantially all of the energised dirt particles colliding thereagainst substantially upwardly towards the second panel portion 62. The concavity of the second surface portion 65 is such that, regardless of the angle of incidence of the energised dirt particles deflected by the first surface portion 64, the second panel portion 62 deflects substantially all of the energised dirt particles colliding thereagainst substantially horizontally towards the outlet 56, and so the exhaust outlet 32. This trajectory for the energised dirt particles is achieved by pairing points on the first surface portion 64 with corresponding points on the second surface portion 65, such that the majority of energised dirt particles striking a first point 82 on the first surface portion 64 will be directed to a corresponding second point 84 on the second surface portion 65. The local curvatures of the first and second surface portions 64, 65 at their respective points 82, 84 is such that an angle qi at which a dirt particle strikes the points 82, 84, relative to respective lines 86 perpendicular to the points 82, 84, equals an angle 0₂ by which the dirt particle is deflected. This arrangement is analogous with the Law of Reflection, in which the angle of an incident ray equals the angle of the reflected ray. After the second panel portion 62, the energy of the dirt particles has dissipated, through the collisions with the first and second panel portions 61, 62, making them more likely to become entrained within the air flow through the dust channel 52. So the deflection surfaces 50a, 50b, 50c are not configured to retain the dirt particles within the dust channel 52, which risks the dirt particles returning to the agitator chamber 40 through either inadvertent collisions or by failing to become entrained into the air flow through the dust channel 52, but to direct the dirt particles towards an area of the cleaner head 10 where the air flow is greatest and consequently they are more likely to become entrained therein.

Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the accompanying claims.

For example, the deflection surfaces 50a, 50b, 50c are shown in FIG. 4b as having a concave profile in the horizontal cross-section. This arrangement has the effect of narrowing the path of the dirt particles following a collision against the first and second surface portions 64, 65. This narrowing of the path may cause a large proportion of deflected dirt particles to collide with each other en route through the dust channel 52, and it may be desirable to minimise these interparticle collisions by preventing the narrowing of the path using deflection surfaces 50a, 50b, 50c that have a straight or planar profile in the horizontal cross-section. Alternatively, some of the deflection surfaces 50a, 50b, 50c might have a concave profile and the remaining deflection surfaces 50a, 50b, 50c might have a straight profile.

Moreover, in the present example of the cleaner head 10, the energised part particles are guided through the dust channel 52 by an initial collision with the first surface portion 64 and a subsequent collision with the second surface portion 65. These sequential collisions guide the dirt particles through the dust channel 52 to the outlet 56, where their energy has sufficiently dissipated that they become entrained within the air flow in the dust channel 52. However, it may be desirable to dissipate the energy of the dirt particles by a greater amount, in which case, each deflection surfaces 50a, 50b, 50c may comprise three or more surface portions configured to disperse the energy of the dirt particles through a sequence of three or more collisions.

Claims

1. A cleaner head (10) for a vacuum cleaning appliance (2), the cleaner head comprising: a main body (12) defining an agitator chamber (40) within which is supported a rotatable agitator assembly (42), and a suction opening (28) through which a portion of the agitator assembly (42) projects to engage a surface to be cleaned, wherein the main body (12) comprises a front section (18) and a rear section (22), the rear section (22) defining an exhaust outlet (32) of the cleaner head (10); and wherein the front section (18) includes a deflection plate (47) comprising a deflection surface (50a, 50b, 50c) which, in use, is impacted by dirt particles energised by the rotation of the agitator assembly (42), and wherein the deflection surface (50a, 50b, 50c) is configured to deflect the energised dirt particles in a direction upwards and over the agitator assembly (42) in a direction away from the suction opening (28) and towards the exhaust outlet (32).

2. A cleaner head (10) according to claim 1, wherein the deflection plate (47) comprises a plurality of deflection surfaces (50a, 50b, 50c) collectively arranged to define a Fresnel reflector in cross-section.

3. A cleaner head (10) according to claim 2, wherein the deflection plate (47) comprises a plurality of deflection panels (48) each of which comprises a respective deflection surface (50a, 50b, 50c) of the plurality of deflection surfaces (50a, 50b, 50c).

4. A cleaner head (10) according to claim 3, wherein the plurality of deflection panels (48) are arranged side-by-side in a direction substantially aligned with a longitudinal axis of the agitator assembly (42).

5. A cleaner head (10) according to claim 4, wherein the plurality of deflection panels (48) are arranged in an arc-like fashion.

6. A cleaner head (10) according to claims 2 to 5, wherein the exhaust outlet (32) defines an exhaust outlet axis (68), and wherein one or more deflection surfaces (50a, 50b, 50c) of the plurality of deflection surfaces (50a, 50b, 50c) are angularly offset from the exhaust outlet axis (68) by a respective offset angle (a, b).

7. A cleaner head (10) according to claim 6, wherein each deflection surface (50a, 50b, 50c) of the plurality of deflection surfaces (50a, 50b, 50c) is located a respective panel distance from a point (71) on the exhaust outlet axis (68), and wherein the panel distance is, for a respective deflector surface (50a, 50b, 50c), proportional to its offset angle (a, b).

8. A cleaner head (10) according to claim 6 or 7, wherein the one or more deflection surfaces (50a, 50b, 50c) of the plurality of deflection surfaces (50a, 50b, 50c) angularly offset from the exhaust outlet axis (68) have a substantially perpendicular relation with respective notional lines (72, 74) extending from the one or more deflection surfaces (50a, 50b, 50c) to intersect the exhaust outlet axis (68).

9. A cleaner head (10) according to any one of claims 2 to 8, wherein one or more deflection surfaces (50a, 50b, 50c) of the plurality of deflection surfaces (50a, 50b, 50c) comprises a first surface portion (64) and a second surface portion (65), said surface portions (64, 65) being divided by a generally horizontal split line (63).

10. A cleaner head (10) according to claim 9, wherein the first surface portion (64) is configured to deflect the energised dirt particles in a direction towards the second surface portion (65).

11. A cleaner head (10) according to claim 9 or 10, wherein the second surface portion (65) is configured to deflect the energised dirt particles in a direction over the agitator assembly (42).

12. A cleaner head (10) according claim 9 or 10, wherein the second surface portion (65) is configured to deflect the energised dirt particles deflected by the first surface portion (64) in a direction over the agitator assembly (42).

13. A cleaner head (10) according to any one of claims 9 to 12, wherein the first and/ or second surface portions (64, 65) have a concave profile in the vertical cross-section.

14. A cleaner head (10) according to any one of claims 9 or 13, wherein the first and/ or second surface portions (64, 65) have a concave profile in the horizontal cross- section.

15. A cleaner head (10) according to any preceding claim, wherein the deflection plate (47) defines at least in part a dust channel (52) that extends rearwardly over the agitator assembly (42).

16. A cleaner head (10) according to claim 15, wherein the dust channel (52) includes an inlet (54) for receiving energised dirt particles from the agitator chamber (40) and an outlet (56) in communication with the exhaust outlet (32).

17. A cleaner head (10) according to claim 16, wherein the inlet (54) of the dust channel (52) extends substantially across the longitudinal width of the agitator assembly (42).

18. A cleaner head (10) according to claim 17, wherein the width of the dust channel (52) tapers between the inlet (54) and outlet (56).

19. A cleaner head (10) according to any one of claims 15 to 18, wherein the main body (12) further comprises a middle section (20) that partly defines the dust channel (52).

20. A cleaner head (10) of any of the preceding claims, wherein the front section (18) is removable from the main body (12).

21. A cleaner head (10) of any of the preceding claims, wherein the deflection surface (50a, 50b, 50c) is pivotably attached to the main body (12).

22. A vacuum cleaning appliance (2) comprising a cleaner head (10) according to any preceding claim.