Noise reduction in vacuum cleaner unit

Abstract

In the field of hand-held vacuum cleaners, there is provided a vacuum cleaner unit (4) comprising a motor fan assembly (10) and a body housing (30) housing the motor fan assembly (10) wherein a sleeve-shaped wall (31) of the body housing (30) is arranged to surround the assembly housing (20) at a distance outside the vacuum cleaner unit (4). The assembly housing (20) has at least one assembly air outlet (25) and the sleeve-shaped wall (31) has at least one main air outlet (36). An air passage (40) from the at least one assembly air outlet (25) to the at least one main air outlet (36) comprises a space present between an outer surface (27) of the assembly housing (20) and an inner surface (37) of the sleeve-shaped wall (31), which helps to reduce noise in the vacuum cleaner unit (4).

Description

Technical Field

[0001] The present invention relates to a vacuum cleaner unit, which is configured to be used as a part of a handheld vacuum cleaner, the vacuum cleaner unit comprising: a motor-fan assembly, the motor-fan assembly comprising a motor and a fan arranged in an assembly housing, the fan being rotatable around the longitudinal axis of the motor-fan assembly; and a main body housing, the main body housing accommodating the motor-fan assembly and having a wall structure, the wall structure comprising a sleeve-shaped wall, the sleeve-shaped wall being arranged to surround the assembly housing at a certain distance in a direction around the longitudinal axis of the motor-fan assembly at the outside of the vacuum cleaner unit, wherein: the assembly housing has at least one assembly air outlet for discharging exhaust gas from the motor-fan assembly, and the sleeve-shaped wall has at least one main air outlet for discharging exhaust gas from the vacuum cleaner unit.

[0002] Furthermore, the present invention relates to a handheld vacuum cleaner comprising the above vacuum cleaner unit. Background Art

[0003] Handheld vacuum cleaners are usually battery powered, so this type of vacuum cleaner is usually cordless and very easy to use. Therefore, handheld vacuum cleaners are becoming more and more popular. Some of the recent developments in the field of handheld vacuum cleaners are aimed at increasing the power level. In view of the fact that in general an increase in the power level involves an increase in the noise generated during operation, finding ways to attenuate / reduce the noise has become more relevant in the field of handheld vacuum cleaners. The choice of noise reduction methods is usually based on the solutions available for conventional canister vacuum cleaners. However, since such solutions are not designed for the context of the specific requirements associated with handheld vacuum cleaners, such solutions usually involve a significant increase in size and weight, as well as a significant increase in cost.

[0004] EP 3 184 011 A1 relates to a battery-powered handheld vacuum cleaner and discloses a handheld vacuum cleaner in which the exhaust airflow from the motor is allowed to take the shortest route to the outside of the vacuum cleaner, generating a large amount of noise. As a measure to reduce noise, EP 3 184 011 A1 proposes to design the air exhaust duct in such a way that the duct is folded at an angle in the range of 120° and 200° (preferably 180°), wherein the airflow needs to follow a longer path before reaching the location of the external outlet. The main body shell is provided with a portion oriented obliquely from the sleeve-shaped wall toward the center of the main body shell, and a portion generally shaped as a cup is provided, the bottom portion of which is raised, thereby forming an inner cone in the cup. The first part and the second part are positioned relative to each other so that the first part extends in the space between the inner cone and the outer wall of the cup of the second part, thereby forming a folded duct, and so that the airflow discharged from the motor follows a path including a backward bend in a direction from the center of the main body shell through the external outlet to the outside of the main body shell.

[0005] In the hand-held vacuum cleaner known from EP 3 184 011 A1, the first part and the second part constitute additional components of the vacuum cleaner. The known noise reduction measures therefore increase the weight and costs of the vacuum cleaner and the design of the vacuum cleaner is also more bulky due to the required larger volume. In addition, the flow resistance in the vacuum cleaner increases significantly.

[0006] EP 1 266 501 A1 relates to a silencer for reducing the noise emission of an airflow generator comprising a motor operating a blower, such as an airflow generator in a vacuum cleaner. The silencer comprises a motor housing defining a volume extending at least radially around the airflow generator, the housing having a wall member extending in a substantially axial direction and provided with at least one inlet airflow passage and at least one outlet airflow passage. At least one of the flow passages comprises at least one folded elongated flow channel integrally formed in the wall member of the motor housing.

[0007] DE 30 27 701 A1 relates to a vacuum cleaner arrangement comprising a duct, a first portion of which is present between the inner surface of an outer housing wall and the outer surface of a component housing, and a second portion of which is present between the inner surface of the outer housing wall and the outer surface of an inner housing wall. In the first portion of the duct, an air channel is present between two rings located in the first portion of the duct as a means for reducing flow noise. Summary of the invention

[0008] An object of the present invention is to provide a vacuum cleaner unit configured to be applied as part of a hand-held vacuum cleaner, the vacuum cleaner unit being designed to achieve significantly lower levels of noise generated by the unit during operation compared to units of conventional design, in a manner that is efficient / minimalistic in terms of the requirements for additional weight, space and cost, and that does not seriously affect mobility performance.

[0009] In view of the foregoing, the present invention provides a vacuum cleaner unit configured to be applied as a part of a handheld vacuum cleaner, the vacuum cleaner unit comprising: a motor-fan assembly comprising a motor and a fan arranged in an assembly housing, the fan being rotatable around a longitudinal axis of the motor-fan assembly; and a main body housing accommodating the motor-fan assembly and having a wall structure, the wall structure comprising a sleeve-shaped wall arranged to surround the assembly housing at a distance in a direction around the longitudinal axis of the motor-fan assembly at the outside of the vacuum cleaner unit, Wherein: the component housing has at least one component air outlet for discharging exhaust gas from the motor fan assembly, and the sleeve-shaped wall has at least one main air outlet for discharging exhaust gas from the vacuum cleaner unit, so that the air passage through which the exhaust gas can pass from the at least one component air outlet to the vacuum cleaner unit to reach the at least one main air outlet includes a space existing between the outer surface of the component housing and the inner surface of the sleeve-shaped wall, and the dimension of the air passage in the longitudinal direction between the outer surface of the component housing and the inner surface of the sleeve-shaped wall is at least twice the dimension of the air passage in the radial direction between the outer surface of the component housing and the inner surface of the sleeve-shaped wall.

[0010] From the above definition of the vacuum cleaner unit according to the invention it follows that, in order to form the path followed by the exhaust gases from the motor-fan assembly through the unit, use is made of the space existing between the outer surface of the assembly housing and the inner surface of the sleeve-shaped wall, in particular the space bounded at least by the outer surface of the assembly housing and the inner surface of the sleeve-shaped wall. The invention is based on the recognition that the position of at least one main air outlet can be selected so as to be as far away as possible from the position of the at least one assembly air outlet in the direction of the longitudinal axis of the motor-fan assembly (this direction is hereinafter referred to as the longitudinal direction) and also so as not to be in the acoustic line of sight from the position of the at least one assembly air outlet as a way of achieving noise reduction without the need to add specific air guiding parts to the existing design of the vacuum cleaner unit. The exhaust gas flow reaches the space between the outer surface of the assembly housing and the inner surface of the sleeve-shaped wall, which surfaces are present in any case in the vacuum cleaner unit, either directly from the at least one assembly air outlet or via a path leading from the at least one assembly air outlet to the space, and the exhaust gas flow is guided between the respective surfaces until the exhaust gas flow reaches the at least one main air outlet, while the noise is reduced along the path due to the continuous collisions between the noise waves in the air flow and the respective surfaces.

[0011] The present invention is particularly applicable to the case of vacuum cleaner units which are designed with a motor-fan assembly and a main body housing accommodating the motor-fan assembly, the main body housing having a wall structure comprising a sleeve-shaped wall arranged to surround the assembly housing at a certain distance in a direction around the longitudinal axis of the motor-fan assembly, which is the case of many known types of vacuum cleaner units which are configured to be applied as part of a handheld vacuum cleaner.

[0012] In view of the fact that a significant aspect of the invention is to design the path followed by the exhaust gas through the vacuum cleaner unit so that the noise waves in the air constantly collide with the surfaces defining the path, the dimension of the air channel in the longitudinal direction between the outer surface of the component housing and the inner surface of the sleeve-shaped wall is at least twice the dimension of the air channel in the radial direction between the outer surface of the component housing and the inner surface of the sleeve-shaped wall. Preferably, even greater multiplication factors are applicable, such as at least three times or at least four times. Another or additional measure in this regard involves arranging at least one main air outlet in the part of the sleeve-shaped wall reached by the longest air path of the exhaust gas from at least one component air outlet. This may involve, in the case of a vacuum cleaner unit, having as large a longitudinal distance as possible between at least one main air outlet and at least one component air outlet. The overall design and dimensions of the vacuum cleaner unit may be such that the air channel covers a major part of the component housing in the longitudinal direction between the outer surface of the component housing and the inner surface of the sleeve-shaped wall, in other words, the dimension of the air channel in the longitudinal direction between the outer surface of the component housing and the inner surface of the sleeve-shaped wall is greater than half of the total dimension of the component housing in the longitudinal direction.

[0013] It is advantageous if the air path of the exhaust air from at least one component air outlet to at least one main air outlet comprises at least one sharp bend. Having at least one sharp bend is a way of having a compact design in the longitudinal direction. Furthermore, having at least one sharp bend is a way of causing multiple collisions between noise waves in the air flow and the surfaces delimiting the sharp bend, whereby energy is dissipated from the sound waves in the air flow, thereby reducing the noise. In other words, it is advantageous if, seen in the longitudinal downstream direction of the motor-fan assembly, at least one component air outlet is located in a forward position relative to the at least one main air outlet. This means that it may be the case that the portion of the air channel defined by the space present between the outer surface of the component housing and the inner surface of the sleeve-shaped wall generally extends in a direction opposite to the longitudinal downstream direction of the motor-fan assembly.

[0014] In a practical embodiment of the vacuum cleaner unit according to the present invention, the wall structure of the main body shell further includes an air guide wall having an inner surface facing the motor fan assembly at a close distance at the location of at least one component air outlet, and the air guide wall is oriented differently from the sleeve-shaped wall. If the air guide wall is included in the wall structure of the main body shell, in fact, this can provide a way to produce an air path for exhaust with at least one sharp bend as described above. The air path can immediately lead upward from at least one component air outlet to the air guide wall, then along the air guide wall towards the periphery of the air guide wall, and then from the air guide wall to at least one main air outlet, passing between the outer surface of the component shell and the inner surface of the sleeve-shaped wall. In order to further enhance the noise reduction at the location of the air guide wall, it is advantageous if the air guide wall includes a material with sound absorption properties at least on one side of the inner surface of the air guide wall. Practical examples of materials with sound absorption properties are foam materials, felt materials or another textile material and rubber materials. Likewise, it is possible if the component housing comprises a material having sound absorbing properties at least on one side of the outer surface of the component housing and / or if the sleeve-shaped wall comprises a material having sound absorbing properties at least on one side of the inner surface of the sleeve-shaped wall. In general, one or more walls of the wall structure of the main body housing may be made completely of a material having sound absorbing properties or may comprise a combination of walls covered with a layer comprising such a material.

[0015] In a practical embodiment of the vacuum cleaner unit according to the invention, the motor fan assembly is of substantially cylindrical shape and the sleeve-shaped wall is substantially shaped as a pipe segment with a circular periphery. In this case, assuming that the wall structure of the main body housing includes the aforementioned wind guide wall, the wind guide wall may be substantially disc-shaped and positioned at the end of the sleeve-shaped wall. The invention encompasses the possibility of providing the sleeve-shaped wall and the wind guide wall as a single integral piece, in which case the piece may be substantially cup-shaped.

[0016] As a further measure aimed at reducing the noise from the exhaust air flow, it may be beneficial if the inner surface of the sleeve-shaped wall comprises a structure comprising at least one ridge, which is arranged to at least partially surround the at least one main air outlet. By applying such a measure, it is achieved that the energy from the noise waves in the exhaust air flow is dissipated just before the air flow flows through the at least one main air outlet, and the noise from the air flow can be heard outside the vacuum cleaner unit. Apart from this, the inner surface of the sleeve-shaped wall may have a substantially smooth appearance.

[0017] In a practical embodiment of the vacuum cleaner unit according to the invention, the wall structure of the main body housing further comprises an air inlet side wall provided with at least one main air inlet for letting air into the vacuum cleaner unit. It may be that the at least one main air inlet and the at least one assembly air outlet are present on opposite sides of the vacuum cleaner unit in a longitudinal direction, in which case having a long air path through the unit may involve locating the at least one main air outlet at a similar longitudinal position as the at least one main air inlet.

[0018] The invention also relates to a handheld vacuum cleaner comprising a vacuum cleaner unit as defined and described above. The handheld vacuum cleaner may be of the type known as a battery-powered handheld vacuum cleaner or a cordless handheld vacuum cleaner. In the handheld vacuum cleaner, the sleeve-shaped wall of the main body housing of the vacuum cleaner unit may be located at the exterior of the vacuum cleaner. Further, the handheld vacuum cleaner may include a handle configured to be held by a user, and the vacuum cleaner unit is arranged close to the handle.

[0019] The above and other aspects of the invention will become apparent from and be elucidated from the following detailed description of practical embodiments of a hand-held vacuum cleaner and of a vacuum cleaner unit which can be used in a hand-held vacuum cleaner. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will now be explained in more detail with reference to the accompanying drawings, in which the same or similar parts are indicated by the same reference numerals, and in which:

[0021] Figure 1 Schematically shows a side view of a handheld vacuum cleaner according to an embodiment of the present invention,

[0022] Figure 2 schematically shows an exploded view of a vacuum cleaner unit according to an embodiment of the invention,

[0023] Figure 3 and Figure 4 schematically shows a cross-sectional view of a vacuum cleaner unit, wherein the exhaust flow from the motor fan assembly of the unit is indicated by arrows,

[0024] Figure 5 schematically shows a cross-sectional view of a vacuum cleaner unit with a portion of the main housing of the vacuum cleaner unit removed, with the exhaust flow from the motor fan assembly of the unit indicated by arrows,

[0025] Figure 6 and Figure 7schematically showing a rear view of a vacuum cleaner unit with a portion of the main housing of the vacuum cleaner unit removed, with the exhaust flow from the motor fan assembly of the unit indicated by arrows, and

[0026] Figure 8 The diagram illustrates options as to where the foam material may be present in the vacuum cleaner unit. DETAILED DESCRIPTION

[0027] Figure 1 An embodiment of a handheld vacuum cleaner 1 according to the invention is shown. It should be noted that this embodiment is a practical one among various possibilities covered by the invention and that aspects of the embodiment to be discussed below should in no way be understood as limiting the invention as defined in the appended claims.

[0028] The hand-held vacuum cleaner 1 shown is suitable for use as a stand-alone vacuum cleaner, or as a functional part of a stick vacuum cleaner. The hand-held vacuum cleaner 1 comprises a dust collection duct 2, the free end of which is suitable for being positioned at or close to a surface from which dust and dirt are to be removed, and is also suitable for being connected to the combination of an elongated tube and a nozzle of a stick vacuum cleaner. The hand-held vacuum cleaner 1 further comprises a handle 3 configured to be held by a user and a vacuum cleaner unit 4. During operation of the hand-held vacuum cleaner 1, the vacuum cleaner unit 4 is used to create an underpressure / suction in the dust collection duct 2, thereby obtaining an inward air flow capable of entraining dust and dirt into the dust collection duct 2. The vacuum cleaner unit 4 is arranged downstream of a container unit 5, which comprises a separator (such as a cyclonic separator) for separating dust and dirt from the incoming air and a space for storing dust and dirt. Reference Figures 2 to 7 , details of an embodiment of a vacuum cleaner unit 4 according to the invention will now be explained.

[0029] Basically, the vacuum cleaner unit 4 comprises a motor fan assembly 10 and a main body housing 30 accommodating the motor fan assembly 10. The motor fan assembly 10 comprises an air inflow nozzle 11, an assembly of a motor 12 and a fan 13 located at a downstream position of the air inflow nozzle 11, and a fixed diffuser 14 located at a position around the motor 12. The air inflow nozzle 11 comprises a flexible material such as a rubber material and has a supporting function in the motor fan assembly 10. The fan 13 is arranged to be rotatable around a longitudinal axis 15 of the motor fan assembly 10, wherein the motor 12 is used to drive the fan 13 to perform an actual rotational movement during operation of the vacuum cleaner unit 4. The motor fan assembly 10 further comprises an assembly housing 20, which in this example comprises a first housing portion 21 arranged to accommodate the motor 12, the fan 13 and the diffuser 14, and a second housing portion 22 covering the first housing portion 21 and the air inflow nozzle 11. The first housing part 21 is generally shaped as a pipe segment, which is partially closed on one side (i.e. the upstream side) and has an annular rim 23 around the opening 24 on the upstream side, wherein the annular rim 23 is tightly surrounded by a part of the air inflow nozzle 11. The second housing part 22 is generally shaped like a pipe segment and is advantageously made of a material with sound absorbing properties (such as a foam material). In this configuration, the downstream side of the assembly housing 20 is an open side, which means that the assembly housing 20 has an assembly outlet 25 for discharging exhaust gas from the motor fan assembly 10. The assembly outlet 25 is partially occupied by the diffuser 14, wherein the annular space around the diffuser 14 is reserved for actually allowing the exhaust gas to pass.

[0030] The main body housing 30 has a wall structure including: a sleeve-shaped wall 31 arranged to surround the assembly housing 20 at a distance in the direction around the longitudinal axis 15 of the motor-fan assembly 10 outside the vacuum cleaner unit 4; a generally disc-shaped wind guide wall 32 having an inner surface 33 facing the motor-fan assembly 10 at a close distance at the position of the assembly air outlet 25 and positioned at one end of the sleeve-shaped wall 31; and an air intake side wall 34 positioned at the other end of the sleeve-shaped wall 31. In order to allow air to enter the vacuum cleaner unit 4 during operation, the air intake side wall 34 is provided with a plurality of main air intakes 35 for allowing air to enter the vacuum cleaner unit 4, and in order to allow exhaust gas to be discharged from the vacuum cleaner unit 4 during operation, the sleeve-shaped wall 31 is provided with a plurality of main air outlets 36.

[0031] The fact is that during operation of the vacuum cleaner unit 4, the fan 13 of the motor-fan assembly 10 rotates, whereby air is sucked into the vacuum cleaner unit 4 through the main air inlet 35. The air passes through the air inflow nozzle 11, reaches the fan 13, and is pushed towards the space between the guide vanes of the diffuser 14 at the location of the first housing part 21 and the inner surface 26 of the assembly housing 20. At the downstream end of the diffuser 14, the air, also referred to at this point as exhaust air, leaves the motor-fan assembly 10 through the assembly air outlet 25, in particular through the annular space surrounding the diffuser 14 at the location of the assembly air outlet 25. The diffuser 14 is shaped so that the exhaust air is discharged from the assembly housing 20 in a swirling motion. In the swirling state, the exhaust air abuts against the inner surface 33 of the air guide wall 32, and subsequently also against the inner surface 37 of the sleeve-shaped wall 31, and travels further downwards towards the main air outlet 36, passing in the process between the outer surface 27 of the assembly housing 20 and the inner surface 37 of the sleeve-shaped wall 31. The exhaust air leaves the vacuum cleaner unit 4 at the location of the main air outlet 36. The path followed by the air through the vacuum cleaner unit 4 is Figures 3 to 7 As described above, among others, this path follows an air passage 40 that enables exhaust air to pass from the assembly air outlet 25 through the vacuum cleaner unit 4 to the main air outlet 36, the air passage 40 comprising the space present between the outer surface 27 of the assembly housing 20 and the inner surface 37 of the sleeve-shaped wall 31.

[0032] Noise is generated during operation of the vacuum cleaner unit 4. There is both direct noise from the motor-fan assembly 10 and airborne noise at the location where the exhaust gas leaves the motor-fan assembly 10. The configuration of the vacuum cleaner unit 4 is selected so that an effective noise reduction is obtained, and this is achieved without the need for complex structural features, such as additional guide elements of a specific shape intended to create a guide channel for the exhaust gas. In the present embodiment, the exhaust gas is guided by the inner surface 33 of the wind guide wall 32 and then between the outer surface 27 of the assembly housing 20 and the inner surface 37 of the sleeve-shaped wall 31. All of the surfaces mentioned are already present in the overall design of the vacuum cleaner unit 4 and no parts are added. An interesting advantage involved in this achievement of the invention is that the construction of the vacuum cleaner unit 4 is robust and is able to absorb well the shocks from the vibrations occurring during operation, or even the shocks resulting from the handheld vacuum cleaner 1 comprising the vacuum cleaner unit 4 falling to the ground for some reason, without structural damage. Furthermore, the design of the vacuum cleaner unit 4 does not require the production of components of the vacuum cleaner unit 4 with high tolerances.

[0033] One aspect of noise reduction is to prevent noise waves in the exhaust air from being able to follow a direct straight path from the assembly air outlet 25 to the main air outlet 36. Another aspect of noise reduction is to have a path followed by the sound waves from the assembly air outlet 25 to the main air outlet 36 which is as long as possible in the case of a vacuum cleaner unit 4. Therefore, in the present embodiment, the position of the main air outlet 36 is chosen to be as close as possible to the air inlet side wall 34, as seen in the direction of the longitudinal axis 15 of the motor fan assembly 10. The fact is that the more opportunities there are for collisions between noise waves in the exhaust air flow and the corresponding surfaces, the more noise is absorbed from the air flow when the air flow reaches the main air outlet 36. In the present embodiment, the fact that the exhaust air needs to take a sharp bend 41 of about 90° to enter the space between the outer surface 27 of the assembly housing 20 and the inner surface 37 of the sleeve-shaped wall 31 has a significant noise reduction effect. Further, it is advantageous if the space between the outer surface 27 of the assembly housing 20 and the inner surface 37 of the sleeve-shaped wall 31, seen in the radial direction, is relatively narrow. exist Figure 4 , the radial dimension r and the longitudinal dimension l of the space are shown, and it can be seen that the longitudinal dimension l is significantly larger than the radial dimension r. For example, the longitudinal dimension l may be about 35 mm, while the radial dimension r may be about 7 mm, which means that the longitudinal dimension l may be about five times the radial dimension r. The invention is by no means limited to this example, and other ratios of the longitudinal dimension l and the radial dimension r are also feasible, wherein it is practical if the longitudinal dimension l is at least twice as large as the radial dimension r. From Figure 4 It can also be seen how the longitudinal dimension l of the space can be greater than half of the overall dimension of the component housing 20 in the longitudinal direction.

[0034] In this embodiment, an additional measure for reducing noise is to provide the inner surface 37 of the sleeve-shaped wall 31 with a structure that is configured to force the exhaust to follow a maze-like path before passing through the main air outlets 36. The structure is selected so that each of the main air outlets 36 is surrounded by a ridge 38. In addition, the main air outlets 36 can be generally elongated in shape, having a relatively large dimension in the longitudinal direction and a relatively small dimension in the direction around the longitudinal axis 15 of the motor fan assembly 10. A practical example of the first dimension is 25 mm, while a practical example of the second dimension is 2 mm. Speaking of examples of dimensions, it should be noted that the outer diameter of the assembly housing 20 can be about 70 mm, while the inner diameter of the main housing 30 can be about 85 mm.

[0035] Figure 8A schematic diagram of a vacuum cleaner unit 4 is provided and serves to illustrate where foam material 45 may be present in the vacuum cleaner unit 4. Also in this figure, the general direction of exhaust air flow from the component air outlet 25 to the main air outlet 36 is indicated by arrows. In general, the use of foam material 45 inside the vacuum cleaner unit 4 is an effective way to reduce noise. As mentioned above, it is advantageous if the second housing part 22 is made of a material having sound absorbing properties, such as foam material 45. This option is shown in FIG. Figure 8 In a more general sense, it is advantageous if the assembly housing 20 includes a foam material 45 on one side of the outer surface 27 of the assembly housing. The effect of having the foam material 45 around the motor 12 is to reduce the direct noise radiated by the motor fan assembly 10 during operation, and also to reduce the airborne noise from the motor fan assembly 10 at the location of the assembly air outlet 25. Further, as Figure 8 As shown, it is advantageous if the sleeve-shaped wall 31 comprises a foam material 45 on one side of the inner surface 37 of the sleeve-shaped wall and likewise if the air guiding wall 32 comprises a foam material 45 at least on one side of the inner surface 33 of the air guiding wall.

[0036] It will be clear to those skilled in the art that the scope of the present invention is not limited to the examples discussed above, but that several modifications and variations may be made thereto without departing from the scope of the present invention as defined by the appended claims. The present invention is intended to be interpreted as including all such modifications and variations as long as they fall within the scope of the claims or their equivalents. Although the present invention has been described and described in detail in the drawings and the specification, such illustration and description are to be considered illustrative or exemplary only and not restrictive. The present invention is not limited to the disclosed embodiments. The accompanying drawings are schematic, details not necessary for understanding the present invention may be omitted, and the drawings are not necessarily drawn to scale.

[0037] Variations of the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention based on a study of the drawings, the specification, and the appended claims. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0038] Unless explicitly stated otherwise, elements and aspects discussed for or in connection with a particular embodiment may be appropriately combined with elements and aspects of other embodiments. Therefore, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0039] Those skilled in the art will understand that the terms "comprising" and "including" as used herein encompass the term "consisting of. Thus, the terms "comprising" or "including" may mean "consisting of" in one embodiment, but may mean "containing / having / equipped with at least the defined substances and optionally one or more other substances" in another embodiment.

[0040] The salient aspects of the invention are summarized as follows. In the field of vacuum cleaners, in particular handheld vacuum cleaners, a vacuum cleaner unit 4 is provided, which comprises a motor fan assembly 10 and a main body housing 30 accommodating the motor fan assembly 10, wherein a sleeve-shaped wall 31 of the main body housing 30 is arranged to surround the assembly housing 20 at a distance outside the vacuum cleaner unit 4. The assembly housing 20 has at least one assembly air outlet 25 for exhausting exhaust gas from the motor fan assembly 20, and the sleeve-shaped wall 31 has at least one main air outlet 36 for exhausting exhaust gas from the vacuum cleaner unit 4. An air passage 40 enabling air to pass from at least one component air outlet 25 through the vacuum cleaner unit 4 to at least one main air outlet 36 comprises a space existing between an outer surface 27 of the component housing 20 and an inner surface 37 of the sleeve-shaped wall 31, which is a feature of the vacuum cleaner unit 4 that helps to reduce noise in the vacuum cleaner unit 4, wherein a dimension l of the air passage 40 between the outer surface 27 of the component housing 20 and the inner surface 37 of the sleeve-shaped wall 31 in the direction of the longitudinal axis 15 of the motor-fan assembly 10 is at least twice a dimension r of the air passage 40 between the outer surface 27 of the component housing 20 and the inner surface 37 of the sleeve-shaped wall 31 in a radial direction relative to the longitudinal axis 15 of the motor-fan assembly 10.

[0041] In the most general sense, the present invention provides a vacuum cleaner unit configured to be used as part of a handheld vacuum cleaner, the vacuum cleaner unit comprising: a motor-fan assembly comprising a motor and a fan arranged in an assembly housing, the fan being rotatable about a longitudinal axis of the motor-fan assembly; and a main body housing accommodating the motor-fan assembly and having a wall structure comprising a sleeve-shaped wall arranged to surround the assembly housing at a distance outside the vacuum cleaner unit in a direction around the longitudinal axis of the motor-fan assembly, wherein: the assembly housing has at least one assembly air outlet for discharging exhaust gas from the motor-fan assembly, the sleeve-shaped wall has at least one main air outlet for discharging exhaust gas from the vacuum cleaner unit, and an air passage enabling exhaust gas to pass from the at least one assembly air outlet through the vacuum cleaner unit to the at least one main air outlet comprises a space existing between an outer surface of the assembly housing and an inner surface of the sleeve-shaped wall, in particular a space defined at least by the outer surface of the assembly housing and the inner surface of the sleeve-shaped wall.

Claims

1. A vacuum cleaner unit (4), the vacuum cleaner unit being configured to be used as a part of a handheld vacuum cleaner (1), the vacuum cleaner unit (4) comprising: A motor-fan assembly (10) comprising a motor (12) and a fan (13) arranged in an assembly housing (20), the fan (13) being rotatable about a longitudinal axis (15) of the motor-fan assembly (10), and a main body housing (30) accommodating the motor-fan assembly (10) and having a wall structure, the wall structure comprising a sleeve-shaped wall (31) arranged to surround the assembly housing (20) at a distance in a direction around the longitudinal axis (15) of the motor-fan assembly (10) outside the vacuum cleaner unit (4), in: The assembly housing (20) has at least one assembly air outlet (25) for discharging exhaust gas from the motor-fan assembly (10), The sleeve-shaped wall (31) has at least one main air outlet (36) for exhausting exhaust air from the vacuum cleaner unit (4), an air passage (40) enabling exhaust air to pass from the at least one module air outlet (25) through the vacuum cleaner unit (4) to the at least one main air outlet (36) comprising a space existing between an outer surface (27) of the module housing (20) and an inner surface (37) of the sleeve-shaped wall (31), and A dimension (l) of the air passage (40) between the outer surface (27) of the assembly housing (20) and the inner surface (37) of the sleeve-shaped wall (31) in the direction of the longitudinal axis (15) of the motor-fan assembly (10) is at least twice a dimension (r) of the air passage (40) between the outer surface (27) of the assembly housing (20) and the inner surface (37) of the sleeve-shaped wall (31) in a radial direction relative to the longitudinal axis (15) of the motor-fan assembly (10).

2. The vacuum cleaner unit (4) according to claim 1, wherein The at least one main air outlet (36) is arranged in the portion of the sleeve-shaped wall (31) reached from the at least one module air outlet (25) via the longest air path of the exhaust gas.

3. The vacuum cleaner unit (4) according to claim 1 or 2, wherein: The dimension (1) of the air passage (40) along the direction of the longitudinal axis (15) of the motor fan assembly (10) between the outer surface (27) of the assembly housing (20) and the inner surface (37) of the sleeve-shaped wall (31) is greater than half of the total dimension of the assembly housing (20) along the direction.

4. The vacuum cleaner unit (4) according to any one of claims 1 to 3, wherein: The air path of the exhaust air from the at least one module air outlet (25) to the at least one main air outlet (36) includes at least one sharp bend (41).

5. The vacuum cleaner unit (4) according to any one of claims 1 to 4, wherein: The wall structure of the main body shell (30) further includes an air guide wall (32), which has an inner surface (33) facing the motor fan assembly (10) at a close distance at the position of at least one assembly air outlet (25), and the air guide wall (32) is oriented differently from the sleeve-shaped wall (31).

6. The vacuum cleaner unit (4) according to claim 5, wherein The wind guide wall (32) comprises a material having sound absorbing properties at least on one side of the inner surface (33) of the wind guide wall.

7. The vacuum cleaner unit (4) according to any one of claims 1 to 6, wherein: The motor fan assembly (10) is generally cylindrical in shape, and wherein the sleeve-shaped wall (31) is generally shaped as a pipe segment having a circular periphery.

8. A vacuum cleaner unit (4) according to claim 7 when appended to any one of claims 5 or 6, wherein The wind guide wall (32) is substantially disc-shaped and is positioned at the end of the sleeve-shaped wall (31).

9. The vacuum cleaner unit (4) according to any one of claims 1 to 8, wherein: The inner surface (37) of the sleeve-shaped wall (31) comprises a structure comprising at least one ridge (38) arranged to at least partially surround the at least one main air outlet (36).

10. The vacuum cleaner unit (4) according to any one of claims 1 to 9, wherein: The wall structure of the main body housing (30) further comprises an air intake side wall (34) provided with at least one main air intake opening (35) for letting air into the vacuum cleaner unit (4).

11. The vacuum cleaner unit (4) according to any one of claims 1 to 10, wherein: The component housing (20) comprises a material having sound absorbing properties at least on one side of the outer surface (27) of the component housing, and / or the sleeve-shaped wall (31) comprises a material having sound absorbing properties at least on one side of the inner surface (37) of the sleeve-shaped wall.

12. The vacuum cleaner unit (4) according to claim 6 or 11, wherein The material having sound absorbing properties is one of a foam material (45), a textile material and a rubber material.

13. A hand-held vacuum cleaner (1) comprising a vacuum cleaner unit (4) according to any one of claims 1 to 12.

14. The hand-held vacuum cleaner (1) according to claim 13, being a battery-powered hand-held vacuum cleaner (1).

15. A handheld vacuum cleaner (1) according to claim 13 or 14, wherein: The sleeve-shaped wall (31) of the main body housing (30) of the vacuum cleaner unit (4) is located at the exterior of the handheld vacuum cleaner (1).

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