TECHNICAL FIELD

The present disclosure relates to a vacuum cleaner comprising an air inlet, an air outlet, and a motor/fan unit configured to generate an airflow from the air inlet to the air outlet.

BACKGROUND

A vacuum cleaner is an apparatus that uses a motor/fan unit to create a partial vacuum in order to obtain an air flow for sucking up dust and dirt from surfaces, such as floors, carpets, furniture, curtains, and the like. The motor/fan unit usually comprises a centrifugal fan and an electric motor configured to power, i.e. , rotate, the centrifugal fan. Several different types of vacuum cleaners exit, including upright/stick type vacuum cleaners, robotic vacuum cleaners, canister vacuum cleaners, hand-held vacuum cleaners, and the like.

A general problem with vacuum cleaners is that the motor/fan unit normally generates a lot of noise during operation. Moreover, the rapid flow of air through channels of the vacuum cleaner may generate noise. The transfer of noise to the surroundings is problematic because it may disturb and annoy the user as well as people and animals in the vicinity of the vacuum cleaner.

Moreover, the fast progress in development of high-power batteries and small electric motors, such as brushless motors, has made battery powered vacuum cleaners able to compete in performance with traditional corded cleaners. Partly as a reason thereof, a current trend for vacuum cleaners is light weighted, small, and easy to handle battery powered vacuum cleaners. In order to keep up air performance with a smaller sized motor/fan unit, many of these motor/fan units have almost doubled the rotational speed in comparison with traditionally large sized motor/fan units. Therefore, these types of motor/fan units can generate more noise than previous types of motor/fan units. Moreover, a slim design together with high power motors puts higher demands on the design of the vacuum cleaner.

One efficient way to supress noise is to use a long air conducting path downstream of the motor/fan unit. However, normally, it is wanted to obtain a compact vacuum cleaner having a slim design, and it may be difficult to accommodate such a long air conducting path inside the available space of the vacuum cleaner. SUMMARY

It is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to an aspect of the invention, the object is achieved by a vacuum cleaner comprising an air inlet, an air outlet, a motor/fan unit configured to generate an airflow from the air inlet to the air outlet, and an air conducting path configured to conduct air from the motor/fan unit to the air outlet. The air conducting path comprises a number of sections, wherein at least one section of the number of sections has a delimiting wall with a corrugated shape in a plane parallel to an airflow direction through the section.

Since the at least one section of the number of sections has a delimiting wall with a corrugated shape in the plane parallel to the airflow direction through the section, conditions are provided for a high level of noise attenuation. This is because the corrugated shape of the delimiting wall in the plane parallel to the airflow direction is able to significantly increase the number of deflections and reflections of the sound propagating through the section of the air conducting path. This can provide a high level of noise attenuation, especially of sound propagating along the airflow direction, i.e. , propagating in a direction towards the air outlet of the vacuum cleaner.

In addition, due to the corrugated shape of the delimiting wall of the at least one section, the travel path for air molecules through the at least one section can be significantly increased, which also provides a noise attenuating effect in a space-efficient manner.

Accordingly, due to these features, conditions are provided for a compact vacuum cleaner generating a low amount of noise.

In addition, due to the corrugated shape of the delimiting wall of the at least one section in the plane parallel to the airflow direction through the section, an improved ability is provided for retaining a noise attenuating material, such as a fibrous noise attenuating material, inside the at least one section of the air conducting path. That is, an airflow through the section of the air conducting path along the airflow direction thereof may apply a force onto noise attenuating material arranged therein in the direction of the air flow. However, due to the corrugated shape of the delimiting wall of the at least one section in the plane parallel to the airflow direction through the section, an improved ability is provided for retaining a noise attenuating material, such as a fibrous noise attenuating material, inside the at least one section of the air conducting path. In other words, due to the corrugated shape of the delimiting wall in the plane parallel to the airflow direction, improved conditions are provided for arranging noise attenuating material inside the at least one section of the air conducting path while being able to retain the noise attenuating material inside the at least one section of the air conducting path. In this manner, the transfer of noise from the motor/fan unit to the air outlet can be further reduced in an efficient manner.

Furthermore, the corrugated shape of the delimiting wall of the at least one section in the plane parallel to the airflow direction through the section may contribute in providing a structurally rigid delimiting wall.

Accordingly, a vacuum cleaner is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the motor/fan unit is configured to generate an airflow having a first direction at an inlet of the motor/fan unit, and wherein the number of sections comprises a first section configured to direct air in a second direction being at least substantially opposite to the first direction. Thereby, conditions are provided for an even higher level of noise attenuation between the motor/fan unit and the air outlet of the vacuum cleaner. This is because conditions are provided for a longer air conducting path between the motor/fan unit and the air outlet of the vacuum cleaner and because noise may be deflected and reflected by surfaces of a portion of the air conducting path at which the airflow changes direction from the first direction to the second direction. In addition, due to these features, conditions are provided for a compact vacuum cleaner generating a low amount of noise.

Optionally, the first section of the air conducting path is arranged radially outside of the motor/fan unit. Thereby, a vacuum cleaner is provided allowing for a long air conducting path downstream of the motor/fan unit while conditions are provided for a compact design of the vacuum cleaner. Accordingly, due to these features, the available space inside the vacuum cleaner is utilized in an efficient manner thereby allowing for a long air conducting path downstream of the motor/fan unit while maintaining a slim and a compact design of the vacuum cleaner. Since a long air conducting path is allowed for downstream of the motor/fan unit, conditions are provided for a high level of noise attenuation. Moreover, because the first section is arranged radially outside of the motor/fan unit, the first section, including the delimiting walls thereof, may per se reduce the transfer of noise from the motor/fan unit to the surroundings.

Furthermore, because the first section is arranged radially outside of the motor/fan unit, the first section may provide cooling of the motor/fan unit. Thereby, conditions are provided for operating the motor/fan unit at higher power levels without overheating the motor/fan unit.

Optionally, the motor/fan unit is configured to generate an airflow having a first direction at an inlet of the motor/fan unit, wherein the air conducting path comprises a first section configured to direct air in a second direction being at least substantially opposite to the first direction and a second section downstream of the first section, and wherein the second section is configured to direct air in a third direction which at least substantially coincides with the first direction. Thereby, conditions are provided for an even longer air conducting path between the motor/fan unit and the air outlet of the vacuum cleaner so as to attenuate noise in a more efficient manner. In addition, since the second section is configured to direct air in a third direction which at least substantially coincides with the first direction, noise can be attenuated in a further efficient manner because noise can be deflected and reflected by surfaces of a transition area between the first and second sections, i.e. , a transition area in which the airflow changes direction from the second direction to the third direction.

Moreover, due to these features, the available space inside the vacuum cleaner can be utilized in an efficient manner while allowing for a long air conducting path downstream of the motor/fan unit to attenuate noise. In other words, due to these features, conditions are provided for a compact vacuum cleaner generating a low amount of noise.

Optionally, each of the first and second sections of the air conducting path is arranged radially outside of the motor/fan unit. Thereby, a vacuum cleaner is provided allowing for a long air conducting path downstream of the motor/fan unit while conditions are provided for a compact design of the vacuum cleaner. Accordingly, due to these features, the available space inside the vacuum cleaner is utilized in an efficient manner thereby allowing for a long air conducting path downstream of the motor/fan unit. Since a long air conducting path is allowed for downstream of the motor/fan unit, conditions are provided for a high level of noise attenuation.

Moreover, since each of the first and second sections of the air conducting path is arranged radially outside of the motor/fan unit, each of the first and second sections, including the delimiting walls thereof, may per se reduce the transfer of noise from the motor/fan unit to the surroundings.

Optionally, the second section of the air conducting path is arranged radially outside of the first section of the air conducting path. Thereby, a structurally simple and compact solution can be provided for transferring air from the motor/fan unit to the air outlet of the vacuum cleaner while being able to attenuate noise in an efficient manner.

Optionally, each of the first and second sections of the air conducting path encloses more than 50% of the circumference of the motor/fan unit in a plane perpendicular to the first direction. Thereby, each of the first and second sections may per se efficiently attenuate noise generated by the motor/fan unit. Moreover, the first and second sections of the first air conducting path can be provided with large cross-sectional areas while maintaining a slim and compact vacuum cleaner. Furthermore, the first air conducting path may provide an efficient cooling of the motor/fan unit. Thereby, conditions are provided for operating the motor/fan unit at even higher power levels without overheating the motor/fan unit.

Optionally, the vacuum cleaner comprises a cup shaped member enclosing at least part of the motor/fan unit, wherein an inner surface of the cup shaped member forms a delimiting wall of the first section of the air conducting path, and wherein an outer surface of the cup shaped member forms a delimiting wall of the second section of the air conducting path. Thereby, a structurally simple and compact solution can be provided for transferring air from the motor/fan unit to the air outlet of the vacuum cleaner while being able to attenuate noise in an efficient manner. Moreover, since the cup shaped member encloses at least part of the motor/fan unit, the cup shaped member may per se reduce the transfer of noise from the motor/fan unit to the surroundings.

Optionally, each of the delimiting wall of the first section and the delimiting wall of the second section has a corrugated shape in a plane parallel to the first direction. Thereby, a vacuum cleaner is provided having conditions for attenuating noise in a further efficient manner. This is because the corrugated shape in the plane parallel to the first direction of each delimiting wall is able to significantly increase the number of deflections and reflections of the sound propagating through each of the first and second sections of the air conducting path, which accordingly provides an enhanced noise attenuating effect. In addition, due to the corrugated shape of the delimiting wall of the second section, the travel path for air molecules through the second section can be significantly increased in a space-efficient manner, which also provides a noise attenuating effect.

In addition, due to the corrugated shape of the delimiting wall of the second section in the plane parallel to first direction, an improved ability is provided for retaining a noise attenuating material, such as a fibrous noise attenuating material, inside the second section of the air conducting path. In other words, due to the corrugated shape of the delimiting wall of the second section, improved conditions are provided for arranging noise attenuating material inside the second section of the air conducting path while being able to retain the noise attenuating material inside the second section of the air conducting path. In this manner, the transfer of noise from the motor/fan unit to the air outlet can be further reduced in an efficient manner.

Furthermore, the corrugated shape of the delimiting wall of the second section, in the plane parallel to the first direction, may contribute in providing a structurally rigid delimiting wall of the second section of the air conducting path.

Optionally, walls of the cup shaped member, which form the inner surface and the outer surface, has an at least substantially equal thickness measured in a plane perpendicular to the first direction. Thereby, conditions are provided for a slim and compact vacuum cleaner while being able to attenuate noise in an efficient manner. In addition, conditions are provided for a structurally rigid cup shaped member.

Optionally, the vacuum cleaner comprises a sleeve shaped member enclosing at least part of the motor/fan unit, and wherein an inner surface of the sleeve shaped member forms a delimiting wall of the second section of the air conducting path. Thereby, a structurally simple and compact solution can be provided for transferring air from the motor/fan unit to the air outlet of the vacuum cleaner while being able to attenuate noise in an efficient manner.

Optionally, the sleeve shaped member encloses the cup shaped member. Thereby, a structurally simple and even more compact solution can be provided for transferring air from the motor/fan unit to the air outlet of the vacuum cleaner while being able to attenuate noise in an efficient manner.

Optionally, the delimiting wall of the at least one section has a non-symmetrical corrugated shape in a plane parallel to an airflow direction through the section. Thereby, an even further improved noise attenuating effect can be provided. This is because noise propagating through the at least one section can deflect and reflect against the delimiting wall of the at least one section in a non-symmetrical manner, which can provide a further improved noise attenuating effect.

Optionally, at least one section of the number of sections has two opposing delimiting walls each having a corrugated shape in a plane parallel to an airflow direction through the section. Thereby, an even further improved noise attenuating effect can be provided. This is because noise propagating through the at least one section is subjected to deflections and reflections against each of the two opposing delimiting walls of the at least one section, which can provide a further improved noise attenuating effect. Moreover, a further improved noise attenuating effect can be provided due to a further prolonged travel path for air molecules through the at least one section.

Optionally, the delimiting wall of the at least one section has a corrugated shape in a plane perpendicular to an airflow direction through the section. Thereby, an even further improved noise attenuating effect can be provided. This is because noise propagating through the at least one section is subjected to deflections and reflections also against the corrugated shape in the plane perpendicular to the airflow direction. Moreover, a further improved noise attenuating effect can be provided due to a further prolonged travel path for air molecules through the at least one section.

Optionally, the corrugated shape of the delimiting wall of the at least one section is arranged such that the difference between a smallest distance and a largest distance between the delimiting wall and a centre line of the at least one section, as measured in a plane parallel to an airflow direction through the section, is within the range of 0.5 mm and 13 mm, or is within the range of 0.8 mm - 6 mm. Thereby, a high noise attenuating effect is ensured while providing conditions for a compact vacuum cleaner with a slim design.

Optionally, the corrugated shape of the delimiting wall of the at least one section is arranged such that the distance between two adjacent ridges of the delimiting wall, as measured in a plane parallel to an airflow direction through the section, is within the range of 2 mm and 27 mm, or is within the range of 5 mm - 15 mm. Thereby, a high noise attenuating effect is ensured while providing conditions for a compact vacuum cleaner with a slim design. Optionally, at least part of the air conducting path is filled with a noise attenuating material. Thereby, the transfer of noise from the motor/fan unit to the air outlet is further reduced in an efficient manner.

Optionally, the at least one section of the air conducting path is filled with a noise attenuating material. Thereby, due to the corrugated shape of the delimiting wall of the at least one section in the plane parallel to the airflow direction through the section, an improved ability is provided for retaining the noise attenuating material inside the at least one section of the air conducting path. That is, the airflow through the at least one section of the air conducting path along the airflow direction thereof may apply a force onto the noise attenuating material arranged therein in the direction of the air flow. However, due to the corrugated shape of the delimiting wall of the at least one section in the plane parallel to the airflow direction through the section, an improved ability is provided for retaining the noise attenuating material therein.

The improved ability for retaining the noise attenuating material is caused by the fact that the corrugated shape of the delimiting wall of the at least one section may ensure that the noise attenuating material is subjected to a varying biasing pressure from the delimiting wall along the flow path of the at least one section of the air conducting path.

Optionally, the vacuum cleaner is a hand-held vacuum cleaner. Thereby, a hand-held vacuum cleaner is provided having conditions for an efficient attenuation of noise while having conditions for being compact.

Optionally, the vacuum cleaner comprises a battery assembly configured to supply electricity to the motor/fan unit. Thereby, a battery powered vacuum cleaner is provided having conditions for an efficient attenuation of noise while having conditions for being compact.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:

Fig. 1 illustrates a vacuum cleaner according to some embodiments, Fig. 2 illustrates a first cross section of the vacuum cleaner illustrated in Fig. 1,

Fig. 3 illustrates an enlarged view of the first cross section of Fig. 2,

Fig. 4 illustrates a second cross section of a portion of the vacuum cleaner 1 illustrated in Fig. 1,

Fig. 5 illustrates a perspective view of a cup shaped member and a motor/fan unit of the vacuum cleaner illustrated in Fig. 1 , and

Fig. 6 illustrates an enlarged view of the first cross section of Fig. 2 and Fig. 3.

DETAILED DESCRIPTION

Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 illustrates a vacuum cleaner 1 according to some embodiments. According to the illustrated embodiments, the vacuum cleaner is a hand-held vacuum cleaner. The wording “hand-held”, as used herein, means that the vacuum cleaner 1 is configured to be operated and supported using one or two hands of a user. In more detail, according to the illustrated embodiments, the vacuum cleaner 1 is a so-called pistol grip handheld vacuum cleaner which can be operated using one hand only.

According to further embodiments, the vacuum cleaner 1 , as referred to herein, may be another type of vacuum cleaner, such as for example a canister vacuum cleaner, an upright/stick type vacuum cleaner, a robotic vacuum cleaner, or the like.

As can be seen in Fig. 1, according to the illustrated embodiments, the vacuum cleaner 1 comprises a handle assembly 20. The handle assembly 20 comprises an elongated handle unit 21. The elongated handle unit 21 is configured to be gripped by a user in an intended grip direction during operation of the vacuum cleaner 1. The handle assembly 20 further comprises a second elongated unit 22 arranged at a distance from the elongated handle unit 21. According to the illustrated embodiments, the second elongated unit 22 is substantially parallel to the elongated handle unit 21. The handle assembly 20 is arranged such that the second elongated unit 22 faces fingers of a user when the user grips the elongated handle unit 21 in the intended grip direction.

The vacuum cleaner 1 comprises an air inlet 3 and an air outlet 5. According to the illustrated embodiments, the air inlet 3 is formed by one central inlet aperture whereas the air outlet 5 is formed by a plurality of outlet apertures. Fig. 2 illustrates a first cross section of the vacuum cleaner 1 illustrated in Fig. 1. As seen in Fig. 2, the vacuum cleaner 1 comprises a motor/fan unit 7. The motor/fan unit 7 is configured to generate an airflow from the air inlet 3 to the air outlet 5.

During operation of the motor/fan unit 7, a partial vacuum is generated at the air inlet 3 which can be used to collect dust. The vacuum cleaner 1 comprises a dust separator 6 between the air inlet 3 and the motor/fan unit 7. According to the illustrated embodiments, the dust separator 6 comprises a cyclone separator. As an alternative, or in addition, the vacuum cleaner 1 may comprise another type of dust separator, such as a dust bag, or the like.

Moreover, according to the illustrated embodiments, the vacuum cleaner 1 comprises a filter 8 arranged between the dust separator 6 and the motor/fan unit 7. The filter 8 may comprise a foam material and may be configured to further separate fine particles from the air flowing towards an inlet 7’ of the motor/fan unit 7. As is further explained herein, the motor/fan unit 7 is configured to generate an airflow having a first direction d1 at the inlet 7’ of the motor/fan unit 7.

The vacuum cleaner 1 comprises an air conducting path 11 configured to conduct air from the motor/fan unit 7 to the air outlet 5. The air conducting path 11 is configured to receive air from an outlet 7” of the motor/fan unit 7 and is configured to conduct the air to the air outlet 5 of the vacuum cleaner 1. Accordingly, the air conducting path 11 is arranged downstream of the motor/fan unit 7 as seen relative to an intended flow direction of air through the vacuum cleaner 1.

As indicated in Fig. 2, the air conducting path 11 comprises a number of sections s1 , s2. According to the illustrated embodiments, the air conducting path 11 comprises two sections s1 , s2, namely a first section s1 and a second section s2. According to further embodiments, the air conducting path 11 may comprise another number of sections s1 , s2.

According to the illustrated embodiments, the vacuum cleaner 1 comprises a battery assembly 25. The battery assembly 25 is configured to supply electricity to the motor/fan unit 7. The battery assembly 25 may comprise a number of rechargeable battery cells, such as a number of lithium-ion battery cells, or the like. As can be seen in Fig. 1 , according to the illustrated embodiments, the battery assembly 25 is supported relative to a main body of the vacuum cleaner 1 via the elongated handle unit 21 and via the second elongated unit 22. The elongated handle unit 21 may therefore also be referred to as a first elongated handle/support unit 21 and the second elongated unit 22 also be referred to as a second support unit 22, or a second handle/support unit 22.

Fig. 3 illustrates an enlarged view of the first cross section of Fig. 2. In Fig. 3, a portion the vacuum cleaner 1 is seen which comprises the air conducting path 11. The first cross section in Fig. 2 and Fig. 3 is made in a plane P1 being parallel to intended airflow directions d2, d3 through the respective first and second sections s1 , s2 of the air conducting path 11. According to the illustrated embodiments, the plane P1 is also parallel to the first direction d1, i.e. , the direction in which the motor/fan unit 7 is configured to generate an airflow upon operation.

In Fig. 3, some features of the motor/fan unit 7 are schematically indicated. In more detail, according to the illustrated embodiments, the motor/fan unit 7 comprises a fan 14 and a motor 16. The motor 16 is configured to rotate the fan 14 around a rotation axis Ax via a shaft 18. The shaft 18 is schematically indicated in dashed lines in Fig. 2. The motor 16 is an electric motor. According to some embodiments, the motor 16 may be a brushless electric motor. According to further embodiments, the motor 16 may be a brushed motor.

The motor 16 comprises a rotor 23 connected to the fan 14 via the shaft 18. According to the illustrated embodiments, the rotor 23, the shaft 18, and the fan 14 are concentrically arranged meaning that they all rotate around the rotation axis Ax during operation of the motor/fan unit 7. The fan 14 may be a radial fan comprising a number of guide wanes configured to generate an airflow by forcing air in radial directions of the fan 14 during rotation of the fan 14. The motor/fan unit 7 may further comprise a diffuser comprising a number of stator blades configured to straighten out the airflow downstream of the fan 14 and thereby increase the operational efficiency of the motor/fan unit 7.

As indicated above, the motor/fan unit 7 is configured to generate an airflow having a first direction d1 at the inlet 7’ of the motor/fan unit 7. According to the illustrated embodiments, the first direction d1 is parallel to the rotation axis Ax of the fan 14, and consequently also parallel to the rotation axis Ax of the shaft 18 and to the rotation axis Ax of the rotor 23 of the motor 16. The first direction d1 may also be referred to as an inlet direction d1 of air flowing into the motor/fan unit 7. The first direction d1 may correspond to an average air flow direction through the motor/fan unit 7 and may also be referred to as an operational air flow direction of the motor/fan unit 7. During operation of the motor/fan unit 7, the air is flowing into the fan 14 via the inlet 7’ of the motor/fan unit 7. The fan 14 forces the air in radial directions of the fan 14, i.e., in directions perpendicular to the first direction d1. The air is then guided through the motor 16 possible via a diffusor as explained above. The air thus flows through the motor 16 and thereby cools the motor 16. The air may flow through the rotor 23 of the motor 16 as well through a stator 26 of the motor 16.

According to the illustrated embodiments, the motor/fan unit 7 comprises an outlet 7” configured to direct air to flow out of the outlet 7” in directions substantially coinciding with the first direction d1. According to further embodiments, the motor/fan unit 7 may comprise one or more outlets configured to direct air to flow out of the outlet in directions differing from the first direction d1 , such that in directions substantially perpendicular to the first direction d1, i.e., in substantially radial directions of the motor/fan unit 7. Such one or more outlets may each be referred to as a radial outlet.

According to the illustrated embodiments, the first section s1 of the air conducting path 11 is configured to direct air in a second direction d2, wherein the second direction d2 is opposite to the first direction d1. According to further embodiments, the first section s1 of the air conducting path 11 may be configured to direct air in a second direction being at least substantially opposite to the first direction d1. An inlet portion of the first section s1 is configured to receive air from the outlet 7” of the motor/fan unit 7.

Moreover, as can be seen in Fig. 2 and Fig. 3, according to the illustrated embodiments, the first section s1 of the air conducting path 11 is arranged radially outside of the motor/fan unit 7. According to the illustrated embodiments, the first section s1 is arranged radially outside of the full length of the motor/fan unit 7 measured in a direction parallel to the first direction d1. According to further embodiments, the first section s1 may be arranged radially outside of the motor/fan unit 7 along more than 40%, or more than 80%, of the length of the motor/fan unit 7 measured in a direction parallel to the first direction d1.

As seen in Fig. 2 and Fig. 3, according to the illustrated embodiments, the second section s2 is arranged downstream of the first section s1. Moreover, the second section s2 is configured to direct air in a third direction d3, wherein the third direction d3 coincides with the first direction d1. According to further embodiments, the second section s2 may be configured to direct air in a third direction which at least substantially coincides with the first direction d1. Moreover, according to the illustrated embodiments, the second section s2 of the air conducting path 11 is arranged radially outside of the first section s1 of the air conducting path 11. In other words, according to the illustrated embodiments, each of the first and second sections s1 , s2 of the air conducting path 11 is arranged radially outside of the motor/fan unit 7. According to the illustrated embodiments, the second section s2 is arranged radially outside of the full length of the motor/fan unit 7 measured in a direction parallel to the first direction d1. According to further embodiments, second section s2 may be arranged radially outside of the motor/fan unit 7 along more than 40%, or more than 80%, of the length of the motor/fan unit 7 measured in a direction parallel to the first direction d1.

In Fig. 2 and Fig. 3, a pair of air filter units 41 , 42 are indicated. The pair of filter units 41 , 42 is arranged in the air conducting path 11 between the second section s2 and the air outlet 5. The pair of air filter units 41 , 42 is configured to further filtrate, i.e., remove, fine particles from air flowing through the air conducting path 11. Moreover, the pair of air filter units 41 , 42 can further attenuate noise generated by the vacuum cleaner 1 as is further explained herein. Each filter unit 41 , 42 of the pair of filter units 41 , 42 may for example comprise a foam material.

As can be seen in Fig. 2 and 3, and as indicated in Fig. 3, according to the illustrated embodiments, each of the first and second section s1 , s2 of the air conducting path 11 has a delimiting wall w1 - w3 with a corrugated shape in a plane P1 parallel to an airflow direction d2, d3 through the respective first and second section s1, s2. According to further embodiments, the air conducting path 11 may comprise only one section having a corrugated shape in the plane P1 parallel to an airflow direction d2, d3 through the section s1 , s2. The corrugated shape of the delimiting walls w1 - w3 provides several advantages, as is further explained herein.

Moreover, as can be seen in Fig. 2 and 3, and as indicated in Fig. 3, according to the illustrated embodiments, the second section s2 of the air conducting path 11 has two opposing delimiting walls w2, w3 each having a corrugated shape in the plane P1 parallel to the airflow direction d2 through the second section s2. Moreover, according to the illustrated embodiments, the first section s1 of the air conducting path 11 has one delimiting wall w1 having a corrugated shape in the plane P1 parallel to the airflow direction d1 through the first section s1 whereas the opposing delimiting wall wT of the first section s1 has a flat shape in the plane P1 parallel to the airflow direction d1 through the first section s1. According to further embodiments, also the opposing delimiting wall wT of the first section s1 may have a corrugated shape in the plane P1 parallel to the airflow direction d1 through the first section s1.

As is further explained herein, the corrugated shape of the delimiting wall w1 - w3 of the at least one section s1 , s2 is configured to attenuate noise propagating towards the air outlet 5 of the vacuum cleaner 1.

Fig. 4 illustrates a second cross section of a portion of the vacuum cleaner 1 illustrated in Fig. 1, wherein the illustrated portion comprises the air conducting path 11. The second cross section of Fig. 4 is perpendicular to the first cross section of Fig. 2 and Fig. 3. In other words, the second cross section of Fig. 4 is made in a plane P2 perpendicular to the first direction d1 and perpendicular to the airflow directions d2, d3 through the respective first and second section s1 , s2 indicated in Fig. 3. Moreover, as understood from the above described, the plane P2 indicated in Fig. 4 is perpendicular to the plane P1 illustrated in Fig. 3. The plane P1 illustrated in Fig. 3 may be referred to as a first plane and the plane P2 illustrated in Fig. 4 may be referred to as a second plane.

As can be seen when comparing Fig. 3 and Fig. 4, according to the illustrated embodiments, each of the first and second section s1 , s2 of the air conducting path 11 has a delimiting wall w1 - w3 with a corrugated shape in the plane P2 perpendicular to the airflow direction d2, d3 through the respective first and second section s1 , s2. According to further embodiments, the air conducting path 11 may comprise only one section having a corrugated shape in the plane P2 perpendicular to an airflow direction d2, d3 through the section s1, s2. The corrugated shape of the delimiting walls w1 - w3 provides several advantages, as is further explained herein.

Moreover, as can be seen when comparing Fig. 3 and Fig. 4, according to the illustrated embodiments, the second section s2 of the air conducting path 11 has two opposing delimiting walls w2, w3 each having a corrugated shape in the plane P2 perpendicular to the airflow direction d2 through the second section s2. Moreover, according to the illustrated embodiments, the first section s1 of the air conducting path 11 has one delimiting wall w1 having a corrugated shape in the plane P2 perpendicular to the airflow direction d1 through the first section s1 whereas the opposing delimiting wall wT of the first section s1 has a flat shape in the plane P2 perpendicular to the airflow direction d1 through the first section s1. According to further embodiments, also the opposing delimiting wall wT of the first section s1 may have a corrugated shape in the plane P2 perpendicular to the airflow direction d1 through the first section s1. In Fig. 4, a circumference c of the motor/fan unit 7 has been marked. Some internal features of the motor/fan unit 7 have been omitted in Fig. 4 for reasons of brevity and clarity. As is clearly seen in Fig. 4, according to the illustrated embodiments, each of the first and second sections s1 , s2 of the air conducting path 11 encloses substantially the entire circumference c of the motor/fan unit 7 in the plane P2 being perpendicular to the first direction d1. According to further embodiments, each of the first and second sections s1 , s2 of the air conducting path 11 may enclose more than 50%, or more than 70%, of the circumference c of the motor/fan unit 7 in the plane P2 perpendicular to the first direction d1.

As is best seen in Fig. 3, according to the illustrated embodiments, the vacuum cleaner 1 comprises a cup shaped member 19. According to the illustrated embodiments, the cup shaped member 19 encloses the full length of the motor/fan unit 7 measured in a direction parallel to the first direction d1. Moreover, according to the illustrated embodiments, the cup shaped member 19 encloses the outlet 7” of the motor/fan unit 7. According to further embodiments, the cup shaped member 19 may enclose at least part of the motor/fan unit 7.

As is indicated in Fig. 3 and Fig. 4, an inner surface 19’ of the cup shaped member 19 forms a delimiting wall w1 of the first section s1 of the air conducting path 11 and an outer surface 19” of the cup shaped member 19 forms a delimiting wall w2 of the second section s2 of the air conducting path 11. Moreover, as is indicated in Fig. 4, according to the illustrated embodiments, the walls 28 of the cup shaped member 19, which form the inner surface 19’ and the outer surface 19”, has an at least substantially equal thickness t measured in the plane P2 perpendicular to the first direction d1.

Moreover, is indicated in Fig. 3 and Fig. 4, according to the illustrated embodiments, the vacuum cleaner 1 comprises a sleeve shaped member 31 enclosing the cup shaped member 19. According to the illustrated embodiments, the sleeve shaped member 31 encloses the full length of the motor/fan unit 7 measured in a direction parallel to the first direction d1. According to further embodiments, the sleeve shaped member 31 may enclose at least part of the motor/fan unit 7. Moreover, is indicated in Fig. 3 and Fig. 4, an inner surface 31’ of the sleeve shaped member 31 forms a delimiting wall w3 of the second section s2 of the air conducting path 11. The sleeve shaped member 31 is also seen and indicated in Fig. 1.

According to the illustrated embodiments, each of the cup shaped member 19 and the sleeve shaped member 31 is formed by a non-air permeable polymeric material. According to further embodiments, one or both of the cup shaped member 19 and the sleeve shaped member 31 may be formed by another type of non-air permeable material. Fig. 5 illustrates a perspective view of the cup shaped member 19 and the motor/fan unit 7 of the vacuum cleaner 1 illustrated in Fig. 1, wherein the motor/fan unit 7 is arranged inside the cup shaped member 19. Moreover, in Fig. 5, the first direction d1 and the rotation axis Ax of the motor/fan unit 7 are indicated.

In Fig. 5, the structure of the inner surface 19’ and the outer surface 19” of the cup shaped member 19 can be clearly seen. As mentioned, according to these embodiments, the inner surface 19’ of the cup shaped member 19 forms a delimiting wall w1 of the first section of the air conducting path whereas the outer surface 19” of the cup shaped member 19 forms a delimiting wall w2 of the second section of the air conducting path.

Moreover, as can be seen when comparing Fig. 3, Fig. 4, and Fig. 5, the structure of the inner surface 19’ and the outer surface 19” of the cup shaped member 19 is such that a corrugated shape of the respective delimiting walls w1, w2 is obtained in a cross section parallel to the first direction d1 , as is seen in Fig. 3, and such that a corrugated shape of the respective delimiting walls w1, w2 is obtained in a cross section perpendicular to the first direction d1 , as is seen in Fig. 4.

Moreover, as seen in Fig. 3, according to the illustrated embodiments, the delimiting walls w1

- w3 of the first and second sections s1, s2 have a substantially symmetrical corrugated shape in the plane P1 parallel to an airflow direction d2, d3 through the section s1, s2.

Likewise, as seen in Fig. 4, according to the illustrated embodiments, the delimiting walls w1

- w3 of the first and second sections s1, s2 have a substantially symmetrical corrugated shape in the plane P2 perpendicular to the airflow direction d2, d3 through the section s1, s2.

According to further embodiments, at least one delimiting wall w1 - w3 of at least one of the first and second sections s1 , s2 may have a non-symmetrical corrugated shape in a plane P1 parallel to an airflow direction d2, d3 through the section s1, s2. Likewise, according to further embodiments, at least one delimiting wall w1 - w3 of at least one of the first and second sections s1, s2 may have a non-symmetrical corrugated shape in a plane P1 parallel to an airflow direction d2, d3 through the section s1, s2.

Fig. 6 illustrates an enlarged view of the first cross section of Fig. 2 and Fig. 3. In Fig. 6, a portion the vacuum cleaner 1 is seen which comprises part of the first and second sections s1 , s2 of the air conducting path 11. As in Fig. 2 and Fig. 3, the first cross section of Fig. 6 is made in a plane P1 parallel to the airflow directions d2, d3 through the respective first and second section s1, s2.

Below, simultaneous reference is made to Fig. 1 - Fig. 6, if not indicated otherwise. The wording “airflow direction d2, d3” through a section s1 , s2 of the air conducting path 11 , as referred to herein, is intended to encompass an average air flow direction through the section s1 , s2 obtained during operation of the motor/fan unit 7.

In the following, the corrugated shape of the delimiting walls w1 , w2, w3 of the first and second sections s1, s2 of the air conducting path 11 is explained in more detail.

The feature that the section s1 , s2 of the air conducting path 11 of the vacuum cleaner 1 has a delimiting wall w1 - w3 with a corrugated shape in a plane P1 parallel to an airflow direction d2, d3 through the section s1, s2 means that the delimiting wall w1 - w3 is shaped into a series of parallel ridges and grooves in the plane P1. In Fig. 6, two adjacent ridges r1 , r2 and two adjacent grooves g1, g2 of the delimiting wall w3 of the second section s2 are indicated. Two adjacent ridges r1 , r2 and two adjacent grooves g1 , g2 have only been indicated on the delimiting wall w3 of the second section s2 in Fig. 6 for reasons of brevity and clarity. However, as is clearly seen in Fig. 6, the opposing delimiting wall w2 of the second section s2, and the delimiting wall w1 of the first section s1 comprises corresponding ridges and grooves.

According to the illustrated embodiments, the corrugated shape of the delimiting walls w1 - w3 of first and second sections s1, s2 are arranged such that the distance dr between two adjacent ridges r1 , r2 of the delimiting wall w1 - w3, as measured in plane plane P1 parallel to an airflow direction d2, d3 through the section s1 , s2, is approximately 10 mm. According to further embodiments, the corrugated shape of the delimiting walls w1 - w3 of first and second sections s1, s2 may be arranged such that the distance dr between two adjacent ridges r1 , r2 of the delimiting wall w1 - w3, as measured in the plane P1 parallel to an airflow direction d2, d3 through the section s1 , s2, is within the range of 2 mm and 27 mm, or is within the range of 5 mm - 15 mm. As understood from the above, even though the distance dr is only marked between the two adjacent ridges r1 , r2 of the delimiting surface w3 of the second section s2, the opposing delimiting wall w2 of the second section s2, and the delimiting wall w1 of the first section s1 comprises corresponding measurements between adjacent ridges in the plane P1 parallel to the airflow direction d2, d3 through the section s1, s2. Moreover, as is clearly seen in Fig. 6, according to the illustrated embodiments, the corrugated shape of the delimiting walls w1 - w3 of first and second sections s1 , s2 are arranged such that the distance dr between two adjacent groves g1 , g2 is approximately the same as the distance dr between two adjacent ridges r1 , r2 of the delimiting wall w1 - w3, as measured in the plane P1 parallel to the airflow direction d2, d3 through the section s1, s2.

Furthermore, according to the illustrated embodiments, the corrugated shape of the delimiting wall w1 - w3 of the at least one section s1 , s2 is arranged such that the difference between a smallest distance sd, sd’ and a largest distance Id between the delimiting wall w1 - w3 and a centre line CL of the at least one section s1 , s2, as measured in the plane P1 parallel to the airflow direction d2, d3 through the section s1, s2, is approximately 2.3 mm. According to further embodiments, the corrugated shape of the delimiting wall w1 - w3 of the at least one section s1, s2 may be arranged such that the difference between a smallest distance sd, sd’ and a largest distance Id between the delimiting wall w1 - w3 and a centre line CL of the at least one section s1 , s2, as measured in a plane P1 parallel to an airflow direction d2, d3 through the section s1 , s2, is within the range of 0.5 mm and 15 mm, or is within the range of 0.8 mm - 6 mm.

Due to these measurements of the corrugations of the delimiting walls w1 - w3 of the sections s1 , s2 of the air conducting path 11 , conditions are provided for a high level of noise attenuation, as is further explained below.

As indicated in Fig. 6, the smallest distance sd, sd’ between the delimiting wall w1 - w3 and the centre line CL may be measured from the centre line CL to a top part of a ridge r1, r2 in the plane P1 parallel to an airflow direction d2, d3 through the section s1 , s2 and along a direction perpendicular to the airflow direction d2, d3 through the section s1, s2. Likewise, the largest distance Id between the delimiting wall w1 - w3 and the centre line CL may be measured from the centre line CL to a bottom part of a groove g1 in the plane P1 parallel to an airflow direction d2, d3 through the section s1, s2 and along a direction perpendicular to the airflow direction d2, d3 through the section s1 , s2. The centre line CL, as referred to herein, may be defined as a straight geometrical centre line extending through a geometrical centre of a section s1 , s2 of the air conducting path 11.

As understood from the above, according to the illustrated embodiments, the distance between the top part of a ridge r1 , r2 and the bottom part of the groove g1 , measured in a direction perpendicular to the airflow direction d2, d3 through the section s1 , s2, is approximately 2.3 mm. According to further embodiments, the distance between the top part of a ridge r1, r2 and the bottom part of the groove g1, measured in a direction perpendicular to the airflow direction d2, d3 through the section s1 , s2, may be within the range of 0.5 mm and 15 mm, or may be within the range of 0.8 mm - 6 mm. As mentioned, conditions are provided for a high level of noise attenuation due to these measurements of the corrugations of the delimiting walls w1 - w3 of the sections s1 , s2 of the air conducting path 11.

According to the illustrated embodiments, the corrugated shape of the delimiting wall w1 - w3 of the at least one section s1 , s2, in the plane P1 parallel to the airflow direction d2, d3 through the at least one section s1 , s2, is such that at least substantially straight wall sections connect ridges r1 , r2 and grooves g1 , g2 in the plane P1. According to further embodiments, the delimiting wall w1 - w3 of the at least one section s1 , s2 may have another type of corrugated shape in the plane P1, such as a smother sinusoidal shape, or other type of undulated or pleated shape.

The corrugated shape of the delimiting wall w1 - w3 of the at least one section s1 , s2 in the plane P2 perpendicular to the airflow direction d2, d3 through the at least one section s1 , s2 may comprise the same, or similar, measurements as explained above for the corrugated shape in the plane P1 parallel to the airflow direction d2, d3. According to the illustrated embodiments, also the corrugated shape of the delimiting wall w1 - w3 of the at least one section s1 , s2, in the plane P2 perpendicular to the airflow direction d2, d3 through the at least one section s1 , s2, is such that at least substantially straight wall sections connect ridges r1 , r2 and grooves g1, g2 in the plane P2. According to further embodiments, the delimiting wall w1 - w3 of the at least one section s1 , s2 may have another type of corrugated shape in the plane P2, such as a smother sinusoidal shape, or other type of undulated or pleated shape.

As mentioned, due to the corrugated shape of the delimiting walls w1 - w3 of the air conducting path 11 , conditions are provided for a high level of noise attenuation. This is because the corrugated shape is able to significantly increase the number of deflections and reflections of the sound propagating through the section s1 , s2 of the air conducting path 11 , which provides a noise attenuating effect. Since the section s1 , s2 of the air conducting path 11 of the vacuum cleaner 1 has a delimiting wall w1 - w3 with a corrugated shape in the plane P1 parallel to the airflow direction d2, d3 through the section s1, s2, a high level of noise attenuation can be provided especially of sound propagating along the airflow direction d2, d3, i.e. , propagating in a direction towards the air outlet 5 of the vacuum cleaner 1. In addition, due to the corrugated shape of the delimiting walls w1 - w3 of the sections s1 , s2 of the air conducting path 11 , the travel path for air molecules through air conducting path 11 is significantly increased which also provides a noise attenuating effect.

Accordingly, due to these features, and the fact that the air conducting path 11 is configured to conduct air from the motor/fan unit 7 to the air outlet 5, the transfer of noise from the motor/fan unit 7 to the air outlet 5 can be significantly reduced. Moreover, due to the features of the vacuum cleaner 1 according to embodiments herein, conditions are provided for a compact vacuum cleaner 1 generating a low amount of noise.

According to the illustrated embodiments, even though not visible in the figures, each of the first and second sections s1 , s2 of the air conducting path 11 is filled with a noise attenuating material. The noise attenuating material may for example comprise a fibrous noise attenuating material. The transfer of noise from the motor/fan unit 7 to the surroundings is further reduced in an efficient manner. According to further embodiments, at least part of the air conducting path 11 of the vacuum cleaner 1 is filled with a noise attenuating material.

Due to the corrugated shape of the delimiting walls w1 - w3 of the first and second sections s1 , s2 in the plane P1 parallel to the airflow direction d2, d3 through the respective first and second sections s1, s2, an improved ability is provided for retaining the noise attenuating material inside the first and second sections s1 , s2 of the air conducting path 11. That is, the airflow through the first and second sections s1 , s2 of the air conducting path 11 along the airflow direction d2, d3 thereof may apply a force onto the noise attenuating material arranged therein in a direction coinciding with the airflow direction d2, d3. However, as mentioned, due to the corrugated shape of the delimiting walls w1 - w3 of the first and second sections s1, s2 in the plane P1 parallel to the airflow direction d2, d3 through the respective first and second sections s1, s2, an improved ability is provided for retaining the noise attenuating material therein.

The improved ability for retaining the noise attenuating material is caused by the fact that the corrugated shape of the delimiting walls w1 - w3 may ensure that the noise attenuating material is subjected to a varying biasing pressure from the delimiting walls w1 - w3 along the flow path of the first and second sections s1 , s2 of the air conducting path 11. In other words, the noise attenuating material can be squeezed between ridges r1, r2 and grooves g1 , g2 of the delimiting walls w1 - w3 of the first and second sections s1 , s2. The wording “substantially parallel to”, as used herein, may encompass that the angle between the objects referred to is less than 10 degrees, or is less than 7 degrees.

The wording “substantially coinciding with” and “substantially coincides with”, as used herein, may encompass that the angle between the objects referred to is less than 10 degrees, or is less than 7 degrees.

The wording “substantially perpendicular to”, as used herein, may encompass that the angle between the objects referred to is within the range of 80 - 100 degrees or is within the range of 83 - 97 degrees.

The wording “substantially perpendicular to”, as used herein, may encompass that the smallest angle between the objects referred to is larger than 165 degrees, or is larger than 173 degrees.

The wording “substantially equal thickness”, as used herein, may encompass that the thickness of the object, as measured in the plane referred to, varies less than 10%.

The wording “substantially symmetrical” as used herein, may encompass that the shape referred to deviates lass than 10% from a symmetrical shape.

The wording “substantially straight”, as used herein, may encompass that the object referred to deviates less than 10% from the shape of a straight line.

The wording upstream and downstream, as used herein, relates to the relative positions of objects in relation to an intended flow direction of air in the air conducting path referred to. As an example, the feature that a first object is arranged upstream of a second object in the air conducting path means that the first object is arranged before the second object seen relative to the intended flow direction of air through the air conducting path. As another example, the feature that a first object is arranged downstream of a second object in the air conducting path means that the first object is arranged after the second object seen relative to the intended flow direction of air through the air conducting path.

It is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended independent claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended independent claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.