WO2017092831A1

WO2017092831A1 - A vacuum cleaner

Info

Publication number: WO2017092831A1
Application number: PCT/EP2015/078720
Authority: WO
Inventors: Henrik Eriksson
Original assignee: Aktiebolaget Electrolux
Priority date: 2015-12-04
Filing date: 2015-12-04
Publication date: 2017-06-08
Also published as: CN108289578A; EP3383242A1; EP3383242B1

Abstract

A vacuum cleaner (1) comprising: a dust collector housing (13) forming a compartment (14) for collecting dust transported by an air flow generated by a motor assembly (16) located externally of the compartment; an opening (25) in a wall (13a) of the housing for allowing air to flow out of the compartment (14) towards a fan (19) of the motor assembly; and a structure (28, 48, 58) provided upstream of the opening and comprising a solid wall portion (28a, 48a, 58a) providing a sound reflective surface for reflecting sound waves from the motor assembly, the structure (28, 48, 58) being arranged such that a clearance (30) is formed between at least a region of the wall (13a) around the opening and the structure (28, 48, 58) to allow air from upstream of the structure to enter the opening via the clearance (30). A sound absorbing material (29) may be located between the solid wall portion (28a, 48a, 58a) and the fan (19).

Description

A VACUUM CLEANER

FIELD

The specification relates to vacuum cleaners. In particular, it relates to a vacuum cleaner comprising a dust collector housing forming a compartment for collecting dust transported by an air flow generated by a motor assembly located externally of the compartment.

BACKGROUND

Vacuum cleaners are popular for removing dust from surfaces. Vacuum cleaners are typically equipped with an electric motor and fan assembly that draws air carrying dust into a dust collector arrangement. A problem with vacuum cleaners on the market is that they generate disturbing noise when operated. Noise sources in a vacuum cleaner include for example the electric motor assembly, the air flow itself and vibrations transferred from the electric motor assembly to a motor assembly housing, a dust collector arrangement housing and a vacuum cleaner casing.

The more acoustic energy that is transmitted from the motor assembly to the other parts of the vacuum cleaner, the more acoustic energy will be transmitted to the outside air. The dust collector arrangement of a vacuum cleaner typically comprises a dust compartment for removing the dust from the air flow and the inlet of the motor assembly housing is connected to an outlet of the dust compartment. Acoustic energy from the fan and the motor of the motor assembly can therefore easily be transmitted directly from the motor assembly to the dust compartment and, even though the dust compartment is a closed compartment, the acoustic energy can then be transmitted to the outside as noise.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a vacuum cleaner comprising: a dust collector housing forming a compartment for collecting dust transported by an air flow generated by a motor assembly located externally of the compartment; an opening in a wall of the housing for allowing air to flow out of the compartment towards a fan of the motor assembly; and a structure provided upstream of the opening and comprising a substantially solid wall portion providing a sound reflective surface for reflecting sound waves from the motor assembly, the structure being arranged such that a clearance is formed between at least a region of the wall around the opening and the structure to allow air from upstream of the structure to enter the opening via the clearance.

By providing a sound reflective surface upstream of the opening in the wall between the dust compartment and the fan, transmission of noise from the motor and the fan of the motor assembly to the outside via the dust compartment can be reduced. The reflective surface reflects a large amount of the acoustic energy from the motor assembly.

The structure is arranged such that at least a portion of the air flowing into the opening will change direction as it flows from upstream of the structure via the clearance into the opening. The structure may extend over the wall around the opening in at least a region and the clearance may be provided between the structure and the wall where they overlap. The vacuum cleaner may comprise a sound absorbing material between the solid wall portion and the fan. The sound absorbing material may be provided between the solid wall portion and the opening. The absorbing material may be an air permeable fibrous synthetic material. The substantially solid wall portion may reflect sound waves from the fan back through the opening towards the fan. The solid wall portion may have a curved shape. It may curve away from the opening to reflect sound waves from the fan or the motor back to the motor assembly through the opening. The solid wall portion may have a parabolic cross-sectional shape with a focal point of the parabola positioned by the opening. The focal point may be positioned by the centre of the opening. The parabolic shape may further reduce the transmission of acoustic energy from the motor assembly in to the dust compartment.

The solid wall portion may extend over a substantial part of the opening to reflect a large amount of acoustic energy from the motor assembly. The solid wall portion may extend over the entire opening. The air may flow around the side of the solid wall portion into the opening. The structure may be arranged such that air flows around the structure into the clearance and then through the opening. The structure may further comprise a supporting portion connected to the solid wall portion and extending at least partially around the solid wall portion, the clearance being provided between the wall of the housing and at least a region of the supporting portion.

The supporting portion may be provided to hold the solid wall portion in place in front of the opening. The supporting portion may be arranged to allow air upstream of the structure to flow around at least part of an edge of the supporting portion into the clearance.

The supporting portion may be a solid structure for preventing air to flow through the supporting portion into the clearance. Alternatively, the supporting portion may comprise air holes for allowing air upstream of the structure to flow into the clearance through the air holes.

The vacuum cleaner may further comprise attachment means for attaching the supporting portion to the housing. The attachment means may comprise attachment elements that form part of the structure. Additionally or alternatively, it may comprise attachment elements that form part of the housing. For example, it may comprise a bracket on the housing. The attachment means may also comprise separate attachment elements that attach to both the structure and the housing. The structure may be rigidly mounted to the housing.

The attachment means may comprise a plurality of attachment elements, each attachment element extending between the supporting portion and the wall around a region of the opening to prevent air from flowing around the edge of the supporting member into the opening in that region. The plurality of attachment elements may comprise two attachment elements located, for example, on opposite sides of the opening. By providing attachment elements that restrict the air flow, the transmission of acoustic energy from the motor assembly into the dust bag compartment is further limited. Alternatively, the attachment means may comprise a plurality of screw pillars for mounting to the housing wall and screws for attaching the supporting portion of the structure to the pillars. The clearance may extend generally orthogonally to the air flow upstream of the structure.

The vacuum cleaner may comprise a dust bag in the compartment and the structure may be arranged to protect the fan if the dust bag breaks.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 shows a vacuum cleaner in which a noise reducing dust collector arrangement is used;

Figure 2 is a schematic diagram of the main body of the vacuum cleaner;

Figure 3 is a schematic diagram of a fan and parts of a dust collector arrangement of the vacuum cleaner;

Figure 4 is a detailed view of components of the dust collector arrangement;

Figure 5 is a detailed view of components of the dust collector arrangement in another implementation; and

Figure 6 illustrates the path of acoustic energy in the dust collector arrangement.

DETAILED DESCRIPTION

Figure 1 shows a vacuum cleaner 1 comprising a vacuum cleaner main body 2, a hose 3, a tube 4, and a nozzle 5. Air carrying dust particles is drawn into the vacuum cleaner 1 through the nozzle 5, the tube 4 and the hose 3 and collected in the main body 2. The hose 3, tube 4 and nozzle 5 may be removably connected to the main body 2. The main body comprises a casing 6 enclosing the internal components of the main body. The casing comprises a port 7 for connecting to the hose 3 and for allowing air to be sucked into the main body 2. The casing 6 also comprises an outlet diffusor 8 for allowing cleaned air to be discharged from the vacuum cleaner. As show in the schematic diagram of Figure 2, the main body of the vacuum cleaner comprises a dust collector arrangement 11 and an air flow generator arrangement 12 within the a vacuum cleaner casing 6. The air flow generator arrangement 11 creates a vacuum, which in turn creates a suction force. The suction force allows the vacuum cleaner 1 to draw in external air and dust from a cleaning surface, through the nozzle 5, tube 4, hose 3 and inlet port 7. Dust is then separated from the air in the dust collector arrangement 11 before the air flows through the air flow generator arrangement 12 and is discharged to the outside through the outlet diffuser 8. The dust collector arrangement 11 may collect dust by filtering, separation or a combination of both. The dust collector arrangement has a housing 13 that forms a dust compartment 14. In Figure 2, a dust bag 15 for filtering the air and thereby collecting the dust in the bag is shown in the dust compartment 14. However, it will be realised that the dust collector arrangement may alternatively comprise a cyclone arrangement that separates dust particles from the air. The housing 13 can have a section that is pivo tally connected to, or removable from, the rest of the housing 13 such that when the dust collector arrangement is arranged to comprise, for example, a dust bag in the dust compartment 14 the dust compartment 14 can be opened and a dust bag 15 can be inserted or removed.

The air flow generator arrangement 12 comprises an electric motor assembly 16 and a motor housing 18. The electric motor assembly 16 is located within the motor housing 18. The air flow generator arrangement 12 may further comprise a motor cover (not shown) around the motor assembly 16. The electric motor assembly 16 comprises a fan 19 and a motor 20 located within a casing 21.

To allow the air to pass through the vacuum cleaner and dust to be collected, the dust collector arrangement 11 comprises an air inlet 24, cooperating with the inlet port 7 of the vacuum cleaner, and an air outlet 25 through which cleaned air exits the dust collector arrangement 11. The air flow generator arrangement 12 comprises an air inlet 26 for receiving the air from the dust collector arrangement 11 and an air outlet 27, cooperating with the outlet diffuser 8. The air inlets 24, 26 and outlets 25, 27 of the dust collector arrangement 11 and the air flow generator arrangement 12 may be formed as openings in the walls of the dust collector arrangement and air flow generator arrangement housing 13, 18. The air outlet 25 of the dust collector arrangement 11 is located adjacent the air inlet 26 of the air flow generator arrangement 12 and a seal (not shown) may be provided between the air outlet 25 and the air inlet 26 to ensure that all the air leaving the dust collector arrangement 11 enters the air flow generator arrangement 12. In some implementations, a single wall, providing part of both or one of the dust collector arrangement housing 13 and the air flow generator arrangement housing 18, may be provided between the dust compartment 14 and the electric motor assembly 16. The air inlet 26 of the air flow generator arrangement 12 would then form part of the same opening in the wall as the air outlet 25 of the dust collector arrangement 11. In this case a seal (not shown) may be provided between the air inlet 26 and the fan 19 to ensure that all the air entering the air inlet 26 enters the fan 19.

When the electric motor assembly 16 is operated, the fan 19 and the motor 20 create the suction force that draws air into the vacuum cleaner. Air enters the main body 2 of the vacuum cleaner 1 through the port 7, passes through the air inlet 24 in the dust collector arrangement 11, flows through the dust collector arrangement 11 and deposits dust in the dust compartment 14 and exits the dust collector arrangement 11 at outlet 25. The air enters the air flow generator arrangement 12 at air inlet 26, is sucked through the motor assembly 16 and then exits through the air flow generator arrangement outlet 27 and the outlet diffuser 8.

The air flow generator arrangement 12 may further comprises a filter (not shown) at the air outlet 27 of the air flow generator arrangement for providing yet another stage of filtration. The filter may for example be a micro filter or a high-efficiency particulate arrestance (HEPA) filter but it will be appreciated that it can be any type of suitable filter. The vacuum cleaner may further comprise another filter (not shown) at the outlet diffuser 8. The dust collector arrangement 11 also comprises a structure 28 upstream of the air outlet 25 of the dust collector arrangement 11 for reflecting sound waves from the motor assembly 16 and thereby restrict the amount of acoustic energy that is transmitted from the motor assembly 16 to the outside via the dust collector arrangement 11. The acoustic energy from the motor assembly 16 may include acoustic energy generated by the fan 19. Alternatively or additionally, it may include acoustic energy generated by the motor 20. Additionally, the dust collector arrangement 11 comprises a sound absorbing material 29 between the structure 28 and the fan 19 for further reducing the transmission of acoustic energy. The structure 28 and the sound absorbing material 29 may therefore reduce the noise emitted by the vacuum cleaner 1. As shown in Figure 2, the sound absorbing material 29 may be provided between the structure 28 and the opening provided by the air outlet 25 of the dust collector arrangement 11. The structure 28 and the sound absorbing element 29 will be described in more detail with respect to Figures 3, 4, 5 and 6.

Although Figure 1 shows a canister type vacuum cleaner, the disclosure is not limited to canister type vacuum cleaners. The vacuum cleaner can alternatively be an upright vacuum cleaner, a battery handheld vacuum cleaner, a battery stick vacuum cleaner, an automatic vacuum cleaner, a robotic vacuum cleaner or any other suitable type of vacuum cleaner. Any suitable type of nozzle, tube and hose may be used for the vacuum cleaner. Nozzles, tubes and hoses for vacuum cleaners are well known and will not be described in detail herein.

The dust collector arrangement 11, the structure 28 for reflecting sound waves and the sound absorbing element 29 will now be described in more detail with respect to Figures 3, 4, 5 and 6. Figures 3 and 6 are schematic diagrams showing the sound reflecting structure 28 upstream of a wall 13a of the housing 13 separating the dust compartment 14 and the fan 19. Figures 4 and 5 show specific implementations of the structure in more detail. Figures 3 and 6 show a simplified housing structure with only a single wall separating the dust compartment 14 and the fan 19. The single wall 13a forms part of the housing 13 of the dust collector arrangement and, in this example, the outlet 25 of the dust collector arrangement 11 also provides an inlet 26 to the air flow generator arrangement 12 and the fan 19. With reference to Figure 3, the structure 28 upstream of the opening 25 comprises a substantially solid wall portion 28a that provides a reflective surface for reflecting sound waves from the fan 19 and the motor 20. The solid wall portion 28a reflects the sound waves back through the opening towards the motor assembly. The solid wall portion 28a covers a substantial part of the air outlet 25 to significantly reduce the amount of acoustic energy from the motor assembly that is transmitted to the outside via the dust compartment 14. The sound waves enter the dust compartment through the opening, hit the solid wall portion 28a of the structure 28 in the dust compartment and are reflected back out of the dust compartment. Consequently, the sound waves are prevented from continuing into the dust compartment past the structure. The structure also comprises a supporting portion 28b connected to the solid wall portion 28a. The supporting portion 28b extends around the solid wall portion 28a. The structure 28 may generally have the shape of a plate, wherein the solid wall portion 28a provides the centre of the plate and the supporting portion 28b provides a peripheral edge of the plate. The supporting portion maintains the solid wall portion in place in front of the opening. The structure is arranged such that a clearance 30 is formed between the wall 13a around the opening and the supporting portion 28b. The solid wall portion 28a and the supporting portion 28b are both set back from the opening and the supporting portion 28b overlaps with the wall 13a in which the opening is formed such that the clearance formed between the wall 13a and the supporting portion 28b provides an air passage for air to flow from upstream of the structure 28 into the opening.

The solid wall portion 28a extends over the opening generally orthogonally to the direction of the air flow from the opening towards the fan. The supporting portion 28b extends around the periphery of the solid wall portion 28a in a direction orthogonal or generally orthogonal to the air flow upstream of the structure so that the clearance 30 also extends orthogonally or generally orthogonally to the air flow direction upstream of the structure. The air flow therefore has to change direction as it travels into the gap between the supporting portion 28b and the wall 13a and then into the opening. The clearance 30 also extends orthogonally or generally orthogonally to the air flow from the opening into the air flow generator arrangement 12 and the air flow therefore has to change direction again as it travels into the opening towards the fan. The air flow passes the structure 28, bends to go through the clearance 30 and then bends again as it travels between an edge 13b of the opening in the housing wall 13a and the solid wall portion 28a in order to enter the opening.

The supporting portion 28b may also be solid such that air will have to travel around the edge of the supporting portion into the clearance, as will be described in more detail with respect to Figure 4. Alternatively, the supporting portion may have holes for allowing air to travel through the supporting portion into the clearance 30, as will be described in more detail with respect to Figure 5. By providing a flow path that only allows the air to pass the structure 28 along the sides of the solid wall portion 28a, and through the clearance, the transmission of acoustic energy from the motor assembly 16 to the dust compartment 14 is further reduced.

The substantially solid wall portion 28a may have a curved shape, as shown in Figure 3. It may curve inwardly away from the opening to reflect sound waves back through the opening. In some implementations, the solid wall portion 28a has the shape of a parabola. The wall may be designed as a parabola with the focal point positioned over the outlet 25 of the dust compartment 14 to minimise the transmission of acoustic energy from the motor assembly 16 to the dust compartment 14. If multiple walls are provided between the dust compartment 14 and the fan 19 the outlet 25 of the dust collector arrangement may be aligned with the inlet 26 of the air flow generator arrangement 12 and the focal point of the parabola may consequently also be positioned over the inlet 26 of the air flow generator arrangement. The focal point may be positioned in the centre or near the centre of the inlet/ outlet. The arrows in Figure 3 indicate how the sound waves from the air flow generator arrangement 12 are reflected back into the air flow generator arrangement 12 by the curved surface of the structure 28. The reflecting wall of the structure therefore restricts the amount of acoustic energy that can be transmitted from the fan and the motor, via the dust compartment, to the outside.

The cross-sectional view of the structure 28 in Figure 3 shows that the solid wall portion 28a of the structure 28 forms a central portion of the structure. In the implementation of Figure 3, the supporting portion 28b is provided by end sections of the structure that have a curved part 28c and a flat part 28d. The curved part curves in the other direction to the curve of the solid wall portion 28a. In other words, the surface of the structure bends back on itself in a convex section 28c before ending in a flat edge section 28d on each side. The flat edge section 28d ends in an edge 28e. The structure 28 is positioned in the dust compartment 14 such that the air can flow around the edge 28e, and also the flat part 28d and the curved part 28c of the supporting portion, to enter the clearance 30. The flat edge section 28d is generally parallel with the wall 13a of the housing. The flat edge section may also be substantially level with the centre of the curved solid wall portion 28a. The end sections may extend all around the solid wall portion forming a single peripheral supporting portion.

The sound absorbing material 29 (not shown in Figure 3) may be provided between the structure 28 and the outlet 25. In some implementations it may be provided in the clearance 30 between the supporting portion 28b and the wall 13a. It may, alternatively or additionally, also be provided between the inlet 26 of the air flow generator arrangement 12 and the fan 19. The sound absorbing material 29 may for example be open celled foam or a fibrous synthetic material but it will be appreciated that any suitable air permeable sound absorbing material can be used. The material may also diffuse the velocity of the air. As a specific example it may comprise Polyethylene Terephthalate (PET) fibres. If a dust bag 15 is used, the structure 28 and the sound absorbing material 29 will also act as a "disaster filter' to protect the fan 19, and the rest of the motor assembly 16, if the dust bag 15 breaks.

The structure 28 is attached to the housing 13. The structure may be rigidly mounted to the housing using attachment elements (not shown in Figure 3). The structure 28 may be attached to the wall 13a of the housing in which the opening 25 to the fan is formed. The structure may be attached to the housing in a way that only allows air to enter into the clearance 30 in specific places.

In implementations using a dust bag 15, the structure 28 would be separate from and not attached to the dust bag. The air enters the dust bag 15, is filtered through the wall of the dust bag and then flows around the solid wall portion 28a to pass through the air outlet 25 towards the fan 19 in the air flow generator arrangement 12.

A specific implementation of the sound reflective structure is shown in Figure 4. As shown in Figure 4, a solid wall 48a of the structure 48 covers the whole of the opening in the wall 13a providing the air outlet 25. In the implementation of Figure 4, the sound reflective surface is provided by a central parabolic solid wall 48a surrounded by a supporting portion 48b. The central solid wall 48a has a circular outline and a cross- sectional shape of a parabola. The supporting portion 48b forms an edge section having a curved part 48c and a flat part 48d ending in an edge 48e as described with respect to Figure 3. The flat part 48d of the supporting portion 48b is generally parallel with the wall 13a of the housing. The flat part 48d is also generally level with the centre of the parabolic curve. The supporting portion 48b is set back from the wall 13a to provide a clearance 30 between the supporting portion 48b and the wall. The structure 48 also comprises attachment elements 48f in the form of elongated plates extending in a plane orthogonal to the plane of the flat parts 48d of the supporting portion. Each attachment plate has one long edge attached to the edge 48e of the flat part 48d of the supporting portion and another long edge in contact with the wall 13a such that the flat part of the supporting portion 48b is parallel or generally parallel with the wall 13a. Each attachment plate extends between the supporting portion 48b and the wall 13a along a portion of the opening 25. The structure may comprise two elongated attachment plates located on opposite sides of the structure 48. The supporting portion 48b in the implementation of Figure 4 is a solid structure and air can therefore not enter through the supporting portion. The air can also not enter around the edges 48e of the supporting portion in the regions where the edges 48e are attached to the attachment plates 48f. In other words, in the implementation in Figure 4, air can only enter through the clearance 30 around the sides of the structure 48 where the attachment plates 48f are not located, as shown by the arrows. In Figure 4, the elongated attachment plates are located at the top and the bottom and air can only enter along the sides of the structure 48 between the supporting portion 48b and the housing wall 13a. Since the air can only enter on the sides, and not from above or below the opening, the transmission of acoustic energy from the motor assembly into the dust compartment 14 is further restricted. Alternatively, the structure may comprise elongated attachment plates at the sides so that the air can enter from the top and bottom between the supporting portion and the housing wall.

The structure may be made from a synthetic resin including but not limited to plastic. The solid wall portion 48a, supporting portion 48b and attachment plates 48f may be integrally formed. They may for example be formed by injection moulding. The housing may also be made from a synthetic resin, including but not limited to plastic. It can comprise a number of components that together form the dust compartment 14. In some implementations, it may be formed as a single piece by injection moulding. The structure 48 may be attached to the housing using snap fit connectors (not shown) that snap the structure into place. For example, the attachment plates 48f may comprise snap fit connectors that snap into or onto corresponding snap fit connectors on the housing wall 13a. Alternatively, the structure may be fixed to the housing using screws. As another alternative, the structure may be integrally formed with the housing. Another implementation of the sound reflective structure in the dust compartment is shown in Figure 5. As shown in Figure 5, the solid wall portion of the structure does not necessarily need to be attached to the housing, using attachment elements, at the top and bottom as shown with respect to Figure 4. However, in Figure 5, a solid wall portion 58a of the structure 58 still covers a sufficient portion of the opening 25 in the dust compartment 14 to reflect a substantial amount of acoustic energy from the motor assembly. As in the implementation of Figure 4, the solid wall portion 58a is designed with a parabolic shape and a supporting portion 58b is formed by a curved part 58c and a flat part 58d ending in an edge 58e. The supporting portion 58b is set back from the housing wall 13a to provide a clearance 30 between the supporting portion 58b and the wall 13a. In the implementation of Figure 5, the flat part 58d, extending along the periphery of the structure 58, is wider than in the implementation shown in Figure 4. Attachment elements 58f are provided in, or extend from, the flat part 58d of the supporting portion 58b. The location of the attachment elements is indicated by the protrusions in the flat part 58d in Figure 5. Spacers may be provided between the supporting portion 58b and the housing wall 13a to create the clearance 30. The spacers may be provided in the form of pillars, each having an end located by one of the protrusions in the flat part 58d of the supporting portion 58b and the other end mounted to the housing wall 13a. The spacers may form part of the attachment elements 58f or may be attached to the structure using the attachment elements. In Figure 5, the structure comprises five attachment elements or areas around the solid wall portion 58a. The structure may be mounted to the housing wall 13a, using the spacers, such that the flat part 58d of the supporting portion 58b is generally parallel to the housing wall 13a.

In the implementation of Figure 5, the supporting portion 58b has a plurality of holes 58g for allowing air to flow through the structure 58. The holes 58g are formed in the wide flat part 58d of the supporting portion 58b. They are provided throughout the wide flat part 58d in-between the attachment elements 58f. The air flows through the holes 58g but also around the edge 58e of the supporting portion, as shown by the arrows in Figure 5, into the clearance 30 and continues between the spacers to the opening. The structure 58 may be made from a synthetic resin including but not limited to plastic. The solid wall portion 58a, supporting portion 58b and attachment elements 58f may be integrally formed. They may for example be formed by injection moulding. The housing may also be made from a synthetic resin, including but not limited to plastic. It can comprise a number of components that together form the dust compartment 14. In some implementations, it may be formed as a single piece by injection moulding. The structure 58 may be screwed into place. For example, when the clearance 30 is formed by pillars between the housing wall 13a and the supporting portion 58b, the pillars may be arranged to receive screws and the attachment elements 58f may connect the screws to the structure. The protrusions in Figure 5 may be protrusions for receiving the heads of the screws that are screwed into the pillars. The screw pillars may be mounted to the housing wall using any suitable method. They may for example be integrally formed with the housing. Alternatively or additionally, the structure 58 may be attached to the housing using snap fit connectors (not shown) that snap the structure into place. The spacers, in the form of for example pillars, may be snap-fitted to the structure instead of using screws. Alternatively or additionally, the spacers may be snap-fitted to the housing wall. As another alternative, the structure 58 may be integrally formed with the housing. Although not shown in Figures 4 and 5, a sound absorbing material 29 may be provided between the structure 48, 58 and the inlet to the fan.

The reflection of sound waves when the sound reflective surface has a parabolic shape is shown in more detail in Figure 6. In Figure 6, the structure 28 has a solid wall portion with a curved surface, facing the outlet 25, having a cross-section shaped as a parabola to limit the transmission of acoustic energy from the motor assembly to the dust compartment and the outside. The focal point of the parabola is positioned over the outlet 25 of the dust compartment. The acoustic energy travels outwards from the fan 19 through the opening 25 and is reflected by the parabolic surface back into the opening. The structure ensures that a large amount of the acoustic energy from the motor assembly will be reflected. This in turn limits the acoustic energy transmitted to the air surrounding the vacuum cleaner and reduces the noise perceived by the user. In known vacuum cleaners only a disaster filter, for protecting the fan if the dust bag breaks, is located between the dust compartment and the fan. However, this will not absorb much acoustic energy or provide any significant reflection of sound waves generated by the motor assembly.

Whilst specific examples and embodiments of the invention have been described, the scope of the invention is defined by the appended claims and not limited to the examples and embodiments described. The invention could therefore be implemented in other ways and numerous modifications and alternative arrangements can be contemplated as would be appreciated by those skilled in the art.

Although the solid wall portion of the sound reflective structure has been described and shown to extend over the entire opening, it will be realised that the structure may only extend over a portion of the opening. Provided that the structure covers a sufficiently large portion of the opening, the structure will reduce the amount of acoustic energy that can be transmitted via the dust compartment to the outside.

Moreover, although the shape of the solid wall portion of the sound reflective structure has been described as curved and parabolic, it will be realised that any suitable shape may be used.

Additionally, although the structure has been described to have a supporting portion that extends around the solid wall portion, it will be realised that other implementations are possible. If a supporting portion is not provided around the solid wall portion, the air may flow around the edge of the solid wall portion.

It will be appreciated that although methods of forming the structure and the housing and attaching the structure to the housing have been described it will be realised that other methods are possible. The structure and the housing may be made using any suitable method and material. Although in the implementations of Figure 4 and 5, it was indicated that the structure may permanently be attached to the housing, the structure may also be removably attached to the housing. For example, the structure may be removable inserted into a bracket in the housing. Moreover, although it has been described that the attachment plates and spacers of the implementations of Figure 4 and Figure 5 can be used to attach the structure to the housing, it will be realised that the structure in the implementations of Figure 4 and Figure 5 may be attached to the housing in other ways. The structure may be attached to the housing such that edges or ends of the attachment plates or spacers are in contact with, or located close to, the housing wall and thereby restrict the air flow in some regions.

Moreover, although specific components of the dust collector arrangement and the air flow generator arrangement have been described with respect to Figure 2, it will be appreciated that the dust collector arrangement and the air flow generator arrangement may comprise additional or alternative components to the ones shown in Figure 2.

The sound reflective structure has been described to reduce the amount of acoustic energy that is transmitted from the motor assembly to outside of the vacuum cleaner. However, it will be appreciated that the structure may also reflect acoustic energy generated by other parts of the vacuum cleaner, further reducing the noise emitted by the vacuum cleaner.

Claims

1. A vacuum cleaner (1) comprising:

a dust collector housing (13) forming a compartment (14) for collecting dust transported by an air flow generated by a motor assembly (16) located externally of the compartment;

an opening (25) in a wall (13a) of the housing for allowing air to flow out of the compartment (14) towards a fan (19) of the motor assembly (16); and

a structure (28, 48, 58) provided upstream of the opening and comprising a substantially solid wall portion (28a, 48a, 58a) providing a sound reflective surface for reflecting sound waves from the motor assembly, the structure (28, 48, 58) being arranged such that a clearance (30) is formed between at least a region of the wall (13a) around the opening and the structure (28, 48, 58) to allow air from upstream of the structure to enter the opening via the clearance (30).

2. A vacuum cleaner according to claim 1 further comprising a sound absorbing material (29) between the substantially solid wall portion (28a, 48a, 58a) and the fan (19).

3. A vacuum cleaner according to claim 1 or 2, wherein the substantially solid wall portion (28a, 48a, 58a) has a curved shape.

4. A vacuum cleaner according to any one of the preceding claims, wherein the substantially solid wall portion (28a, 48a, 58a) has a parabolic shape with a focal point positioned by the opening.

5. A vacuum cleaner according to any preceding claim, wherein the substantially solid wall portion (28a, 48a, 58a) extends over the entire opening.

6. A vacuum cleaner according to any preceding claim, wherein the structure further comprises a supporting portion (28b, 48b, 58b) connected to the solid wall portion and extending at least partially around the solid wall portion, the clearance being provided between the wall (13a) of the housing and at least a region of the supporting portion (28b, 48b, 58b).

7. A vacuum cleaner according to claim 6, wherein the supporting portion (28b, 48b, 58b) is arranged to allow air upstream of the structure (28, 48, 58) to flow around at least a part of an edge (28e, 48e, 58e) of the supporting portion into the clearance (30).

8. A vacuum cleaner according to claim 6 or 7, wherein the supporting portion (28b, 48b, 58b) is a solid structure for preventing air to flow through the supporting portion.

9. A vacuum cleaner according to claim 6 or 7, wherein the supporting portion (58b) comprises air holes (58g) for allowing air upstream of the structure (58) to flow into the clearance through the air holes.

10. A vacuum cleaner according to any one of claims 6, 7, 8 and 9, further comprising attachment means (48f, 58f) for attaching the supporting portion (48b, 58b) to the housing ( 3).

11. A vacuum cleaner according claim 10, wherein the attachment means (48f) comprise a plurality of attachment elements, each attachment element extending between the supporting portion and the wall (13a) around a region of the opening to prevent air from flowing around the supporting member into the opening in said region.

12. A vacuum cleaner according to claim 11, wherein the plurality of attachment elements (48f) comprises two attachment elements located on opposite sides of the opening (25).

13. A vacuum cleaner according to any preceding claims, wherein the structure (28, 48, 58) is rigidly mounted to the housing (13).

14. A vacuum cleaner according to any preceding claim, wherein the clearance (30) extends generally orthogonally to the air flow direction upstream of the structure (28, 48,

58).

15. A vacuum cleaner according to any preceding claim, further comprising a dust bag (15) in the compartment (14), the structure (28, 48, 58) further being arranged to protect the fan (19) if the dust bag breaks.