fan

Abstract

According to an aspect of the invention, there is provided a fan comprising: a housing defining an inner region; an inlet for receiving an air flow; an outlet for expelling the air flow; an impeller having a plurality of fan blades that generate sound pressure waves within the inner region on operation of the fan; and a conduit configured to attenuate the generated sound waves that travel through the outlet such that an attenuation of the sound waves is at least 50%, the conduit comprising: an outer wall surrounding an air passage along which the air flow is caused to flow on operation of the fan; and a sound absorbing material provided between the air passage and the outer wall.

Description

Field of the invention

[0001] The present invention relates to fans, and more specifically, fans with improved noise reduction.Background to the invention

[0002] It is known to provide fans which supply air to a range of devices. Fans may provide heated or cooled air depending on the application of the device. For example, fans can be used in combination with medical devices such as temperature optimisation blankets for post-operative patient care. Used in this way, the fan can provide air of optimum temperature to a patient recovering from surgery or another medical procedure.

[0003] Fans typically comprise a central impeller with blades that is enclosed by a housing. As the blades are turned, the velocity of the blades is different to the velocity of the air surrounding the blades in the housing and this causes pressure waves (repeating regions of higher and lower pressure) to be formed. The pressure wave causes vibration of the air molecules which results in an acoustic wave, and therefore sound. This can make the fans very noisy. These fan devices do not therefore provide a calm and peaceful environment for a user and are non-ideal for a patient in a medical setting. Some sound reduction devices for industrial fans are known.

[0004] It is in this context that the present inventions have been devised.Summary of the invention

[0005] In accordance with an aspect of the present invention, there is provided a fan. The fan comprises a housing defining an inner region. The fan comprises an inlet for receiving an air flow. The fan comprises an outlet for expelling the air flow. The fan comprises an impeller having a plurality of fan blades that generate sound pressure waves within the inner region on operation of the fan. The fan comprises a conduit configured to attenuate the generated sound waves that travel through the outlet such that an attenuation of the sound waves is at least 50%. The conduit comprises an outer wall surrounding an air passage along which the air flow is caused to flow on operation of the fan. The conduit comprises a sound absorbing material provided between the air passage and the outer wall.

[0006] Advantageously, the sound absorbing material absorbs a portion of sound energy from the generated sound waves to thereby attenuate the sound waves which are generated by the impeller and travel through the outlet. As a result, the noise output of the fan is reduced. This makes the fan particularly suitable for applications where a reduced noise output is highly desirable, for example for use in a medical setting where patients are exposed to the noise of the fan.

[0007] It may be that the conduit comprises an inner wall. It may be that the inner wall defines a plurality of apertures therein. It may be that the sound absorbing material is provided between the inner wall and the outer wall.

[0008] Advantageously, the apertures allow sound to pass from the air passage, through the inner wall to the sound absorbing material. It will be understood that by having apertures therein, rather than simply being absent entirely, the inner wall allows for some of the sound waves within the sound absorbing material between the inner wall and the outer wall, to be reflected back into the sound absorbing material when they travel towards the inner wall, rather than passing through the outlet. This further improves the reduction in the noise output of the fan.

[0009] It may be that the inner wall is formed of a reflective material.

[0010] Advantageously, when the inner wall is formed of a reflective material, the sound waves are reflected so the phase of the sound waves is shifted, meaning that the sound waves at least partially undergo destructive interference. This results in noise cancellation which further reduces the noise output of the fan.

[0011] Typically, the inner wall is formed of material that reflects sound waves. Typically, when the sound waves from the air passage impact the inner wall, where there is no aperture, the sound wave is redirected away from the inner wall into the air passage. The sound waves may continue to impact and rebound from reflective inner wall as the sound waves pass through the conduit.

[0012] It may be that the reflective material is a hard and / or smooth material. It may be that the reflective material comprises a metal, such as steel, aluminium or copper. It may be that the reflective material comprises a plastics material such as polycarbonate or polyvinyl chloride (PVC). Advantageously, a plastics material is particularly low weight and is therefore suitable for applications where a low weight is desirable (e.g. in a fan for a temperature control blanket).

[0013] It may be acoustic reflection co-efficient of the reflective material is for example at least 0.9, such as at least 0.95, for example at least 0.975, such as at least 0.985, for example at least 0.99, such as at least 0.995, for example at least 0.099.

[0014] The housing may comprise an impeller surrounding portion. The housing may comprise an inlet-forming portion. The housing may comprise an outlet-forming portion. The housing may comprise a first inner wall and a second inner wall, which is opposite to the first inner wall. The inner region may have a depth extending between the first inner wall and the second inner wall.

[0015] The housing may be arranged as a curved funnel that increases in area as it approaches the outlet-forming portion. For example, the housing may be arranged as a volute having an end portion which forms the outlet. The volute may have a first portion that at least partially surrounds the impeller and a second portion that extends from the first portion to form the outlet at an end of the second portion.

[0016] The housing may be made up of two side panels and the inlet may be on one or both the side panels. Air may enter the inlet substantially at right angles to the direction of air flow in the inner region. Air flow may circulate in the inner region defined by the housing and exit through the outlet.

[0017] The outlet may be formed as an end part of the volute. The outlet may be cylindrical. The outlet may be configured for connection with a medical device such as a patient temperature control blanket or gown.

[0018] When the fan is in operation, the blades may be configured to rotate at a predetermined fan speed. It may be that the fan is configured to be controlled to vary the predetermined fan speed.

[0019] A large proportion of the sound waves in the fan are generated at the blade passing point (the point at which the blades pass the outlet-forming portion). The frequency of the generated sound waves inside the fan is proportional to the speed of the fan and to the number of blades in the impeller. Accordingly, the sound waves may have different frequencies depending on the speed of the fan and the number of blades in the impeller. The generated sound waves may have a frequency of between 420-460Hz. The speed of the fan may be between, for example, 200 to 10,000 revolutions per minute (rpm), such as between 1,000 to 10,000 rpm, for example between 1,800 to 3,600 rpm (or radians per second = angular velocity SI unit). The number of fan blades may be between, for example, 3 and 50.

[0020] The fan may be configured such that rotation of the fan blades occurs about a first axis, defining a first axial direction, relative to a first radial direction perpendicular to the first axial direction. The impeller may be located at a first axial depth along the first axis. The first and second inner walls may each extend in a plane perpendicular to the first axial direction.

[0021] The air passage may be a channel through which the air flow is caused is to move. The generated sound waves may travel through the air passage. Typically, the sound absorbing material may define the air passage. Typically, the inner wall of the conduit, when present, may define the air passage. The outer wall may not directly surround the air passage. It may be that the sound absorbing material (and the inner wall when present) are positioned between the air passage and the outer wall. It may be that the air passage is linear. The conduit may be cylindrical. The inner wall may be cylindrical. The outer wall may be cylindrical. The inner wall may be radially inwards of the outer wall. The sound absorbing material may be radially inwards of the outer wall.

[0022] The conduit may be positioned within the housing of the fan. The conduit may be arranged in a path of the air flow between the impeller and the outlet. The conduit may be configured to attenuate the generated sound waves before they travel through the outlet. The conduit may be configured to attenuate the generated sound waves as they travel through the outlet. The conduit may be configured to attenuate the generated sound waves after they have travelled through the outlet. The conduit may be provided adjacent to the outlet. The conduit may be provided within the housing and adjacent to the outlet. The conduit may be provided outside of the housing and adjacent to the outlet.

[0023] It may be that the conduit is configured to attenuate the generated sound waves that travel through the outlet such that an attenuation of the sound waves is at least 50%, for example at least 60%, such as at least 70%, for example at least 80%, such as at least 90%, for example at least 95%. It will be appreciated that the attenuation of the generated sound waves is the reduction in amplitude of the generated sound waves over a given distance.

[0024] Attenuation of the sound wave is caused by absorption and scattering of the sound wave. The attenuation of the generated sound waves can be determined by measuring the sound pressure level of the sound waves generated by the fan at the impeller and the sound pressure level of the sound waves after they have passed through the conduit.

[0025] Typically, the length of the conduit (i.e. the distance along which the generated sound waves travel through the conduit) is in a second axial direction. The first and second axial directions may be perpendicular to one another.

[0026] The length of the conduit may be at least 0.05m, for example at least 0.1m, such as at least 0.5m, for example at least 1m, such as at least 1.5m, for example at least 1.8m. The length of the conduit may be at most 3m, for example at most 2.5m, such as at most 2m, for example at most 1.5m, such as at most 1m, for example at most 0.5m, such as at most 0.1m.

[0027] It may be that the width of the conduit (i.e. in a direction perpendicular to the second axial direction) is at least 5cm, for example at least 10cm, such as at least 12cm, for example at least 15cm. It may be that the width of the conduit (i.e. in a direction perpendicular to the second axial direction) is at most 30cm, for example at most 25cm, such as at most 20cm, for example at most 15cm.

[0028] Typically, the plurality of apertures may be of a uniform size. The apertures may be circular in shape. The apertures may be square in shape. The apertures may be elliptical in shape. The plurality of apertures may be positioned at regular intervals along the inner wall. For example, the plurality of apertures may be arranged in rows along the second axial direction and / or arranged in a circumferential line.

[0029] Typically, the number of apertures per unit surface area of the inner wall (cm 2< ) is at least 1, for example at least 5, such as at least 10, for example at least 20, such as at least 50. Typically, the number of apertures per unit surface area of the inner wall (cm 2< ) is at most 80, for example at most 50, such as at most 20, for example at most 10.

[0030] The apertures may be for example at least 0.001m, such as at least 0.002m, for example at least 0.003m, such as at least 0.004m, for example at least 0.005m, such as at least 0.006m, for example at least 0.007m, such as at least 0.008m, in diameter. The apertures may be for example at most 0.01m, such as at most 0.009m, for example at most 0.008m, such as at most 0.007m, for example at most 0.006m, such as at most 0.005m, for example at most 0.004m, such as at most 0.003m, in diameter.

[0031] It may be that the apertures form for example at least 10%, such as at least 20%, for example at least 30%, such as at least 40%, for example at least 50% of the surface area of the inner wall. It may be that the apertures form for example up to 90%, such as up to 80%, for example up to 70%, such as up to 60%, for example up to 50% of the surface area of the inner wall.

[0032] Typically, when the inner wall is present, the generated sound waves pass through the plurality of apertures to contact the sound absorbing material. Typically, when the inner wall is present and it is formed of a reflective material, the generated sound waves may be reflected from the reflective material (if incident on a part of the inner wall which does not have an aperture). In other examples, where the inner wall is not present, the generated sound waves directly contact the sound absorbing material.

[0033] The sound absorbing material may be configured such that, when the generated sound waves pass through the plurality of apertures, the generated sound waves are absorbed (i.e. energy from the generated sound waves is absorbed by transfer of kinetic energy of the particles of the medium in which the sound wave travels to thermal energy of the particles in the sound absorbing material) and reflected randomly off the sound absorbing material. This random scattering and absorption will cause the amplitude of the generated sound waves to be reduced. Other mechanisms of sound absorption will be envisaged.

[0034] The type of sound absorbing material and / or number of apertures may be chosen to provide a desired level of attenuation of the generated sound waves.

[0035] It may be that the sound absorbing material covers the entire inner surface of the outer wall of the conduit. It may be that the sound absorbing material contacts the outer wall.

[0036] It may be that the conduit is provided at the outlet.

[0037] Advantageously, provision of the conduit at the outlet results in the absorption of energy from the sound waves as the air flow is expelled from the fan. This means that the noise output of the air flow being expelled from the fan is reduced.

[0038] The conduit may be provided at the outlet in that the conduit (i.e. the inner wall) defines the outlet.

[0039] It may be that the conduit is provided in a component part that is connected to the housing.

[0040] Advantageously, provision of the conduit as a component part means that the component part can be fitted to multiple types of fans, including retrofitted to existing fans. As a result, the existing components of the fan do not need to be changed to benefit from noise reduction as this is provided by the conduit component part.

[0041] It may be that the component part is configured to be connected to the housing by way of a threaded connection or a latching mechanism. The component part may be configured to facilitate connection of the housing to another part, such as in the fan assembly discussed below. It may be the component part comprises a first end connected to the housing and a second end connected to another part. It may be that the component part is configured to be connected to the outlet of the fan.

[0042] It may be that the sound absorbing material has a sound absorbing coefficient of at least 0.5.

[0043] Advantageously, sound absorbing material having a sound absorbing coefficient of at least 0.5 is particularly effective at absorbing energy from sound waves. Therefore, use of this type of material results in increased attenuation of the sound waves.

[0044] The sound absorbing coefficient of the sound absorbing material may be determined in accordance with the provisions set forth in ISO 354 which specifies a method of measuring the sound absorption coefficient of acoustical material. It may be that the sound absorbing material has a sound absorbing coefficient of at least 0.5, for example at least 0.6, such as at least 0.7, for example at least 0.8, such as at least 0.9, for example at least 0.95.

[0045] It may be that the sound absorbing material is selected from at least one of a foam, a mineral wool, or a combination of the two.

[0046] Advantageously, a foam, a mineral wool, or a combination of the two is particularly effective at absorbing energy from sound waves. Therefore, use of this type of material results in increased attenuation of the sound waves.

[0047] It may be that the sound absorbing material comprises a foam. It may be that the sound absorbing material comprises a mineral wool. It may be that the sound absorbing material comprises a combination of mineral wool and foam.

[0048] In accordance with an aspect of the invention, there is provided a fan assembly. The fan assembly comprises a fan as described above, and a hose connected to the fan outlet.

[0049] Advantageously, the conduit having the sound absorbing material absorbs energy from the generated sound waves and scatters the sound waves to reduce the noise output of air expelled from the fan and into the hose.

[0050] The hose may be formed of a flexible material. The hose may be configured to direct the air flow to a blanket for post-operative patient care.

[0051] It may be that the component part is configured to connect the hose to the fan outlet.

[0052] Advantageously, the conduit is provided on a component part which has the dual functionality of reducing the noise output of the fan and facilitating connection of the hose to the housing of the fan. This reduces the number of components needed in the fan assembly.

[0053] It may be that the component part is configured to provide an interface between the hose and the housing that dampens the sound of the expelled air flow.

[0054] It may be that the conduit is a hose. Advantageously, the noise dampening provided by the conduit may be provided along the entire length of the hose to further reduce noise output from the fan. It may be that an end of the conduit (i.e. the outlet of the conduit) is connected to an external device, such as a temperature control blanket.

[0055] The fan and fan assembly described above may be used in medical applications. The fan and fan assembly described above may be used in medical applications for patient temperature management.Description of the Drawings

[0056] An example embodiment of the present invention will now be illustrated with reference to the following Figures in which: Figure 1 is a schematic of a fan according to an aspect of the invention; Figure 2 is a schematic of a side view of a conduit according to an aspect of the invention; Figure 3 is a cross section along the A-A' direction of a schematic of a conduit according to an aspect of the invention; Figure 4 is an end view of a schematic of a conduit according to an aspect of the invention; Figure 5 is a schematic of a fan assembly according to an aspect of the invention; Figure 6 is a schematic of a side view of a conduit according to an aspect of the invention; Figure 7 is a cross section along the B-B' direction of a schematic of a conduit according to an aspect of the invention; and Figure 8 is an end view of a schematic of a conduit according to an aspect of the invention. Detailed Description of an Example Embodiment

[0057] Figure 1 is a schematic of a fan 100 according to an aspect of the invention. The fan 100 includes a fan housing 110 which defines an inner region 120. The fan 100 includes an impeller 150 which is made up of fan blades 160. The fan blades 160 rotate in the direction shown by the curved arrow 165. The impeller 150 is housed in a portion of the inner region 120 which surrounds the impeller 150 and is defined by a portion 111 of the housing 110, functioning as the impeller surrounding region described hereinbefore. An inlet 130 to the fan 100 is positioned at the axis of rotation of the impeller 150, such that air is drawn into the fan 100 along a first axial direction (directed out of the page). The housing 110 also has a portion 112, functioning as the outlet-forming portion discussed hereinbefore, which is shaped so as to define an outlet 140. A first end 206 of a conduit 200 is attached to the fan housing 110. Air flow is expelled out of the fan through the outlet 140 and into the air passage 215 in the direction of the straight arrow 141, which represents the second axial direction which is the axial direction of the conduit 200 as described hereinbefore.

[0058] When the fan 100 is operated, the blades 160 rotate in the direction 165b. This causes air to be drawn in through the inlet 130 and air to be expelled from the fan through the outlet 140 and the air passage 215. When the blades 160 rotate, sound pressure waves are generated by rotation of the blades. The sound waves also travel through the outlet 140 and the air passage 215. The conduit 200 absorbs the energy from the sound waves to attenuate the sound waves to reduce the noise output of the fan. This is achieved by the features of the conduit 200 which will now be described.

[0059] Figure 2 is a schematic of a side view of the conduit 200 according to an aspect of the invention. Figure 3 is a cross section along the A-A' direction of a schematic of the conduit 200 according to an aspect of the invention. Figure 4 is an end view of a schematic of the conduit 200 according to an aspect of the invention. The conduit 200 is formed of a sound absorbing material 235 sandwiched between an inner wall 205 and an outer wall 245. In this example, the sound absorbing material 235 is a mineral wool having a sound absorbing coefficient of 0.7. However, other materials and other sound absorbing coefficients can be used in the invention as discussed hereinbefore.

[0060] The conduit 200 is cylindrical, where the inner wall 205 forms a cylinder having a smaller radius that the radius of the outer wall 245, which is also a cylinder. The inner wall 205 defines the air passage 215 through which the sound waves travel and the air flows. The conduit 200 extends from a first end 206 to the second end 207 in the axial direction 141.

[0061] The inner wall 205 includes apertures 225a, 225b, 225c which expose areas of the sound absorbing material 235 underneath to the air passage 215. The apertures are arranged in rows along the axial direction of the conduit 200, which is the direction 141 of air flow. Adjacent rows of apertures are shown as being offset from one another. However, it will be appreciated that the configuration of the apertures shown in Figures 2 to 4 is exemplary and other configurations will be envisaged. The configuration of the apertures (including the size, shape and spacing) can be provided as necessary to achieve the desired attenuation of the generated sound waves.

[0062] When the generated sound waves pass through the air passage 215, they do not all pass straight through the air passage 215 linearly in the direction indicated by the arrow 141. The majority of the generated sound waves are incident on the inner wall 205 in random directions. The sound waves that are incident on the inner wall 205 are reflected back into the air passage 215, where they may then leave the conduit 200 or be further reflected from other parts of the inner wall 205. The sound waves incident on the inner wall 205 are reflected with substantially the same amount of energy as the energy of the sound wave when it was incident on the inner wall 205.

[0063] The sound waves that pass thorough the apertures 225a, 225b, 225c on the inner wall 205 are incident on the areas of the sound absorbing material 235 which are exposed through the respective aperture. The sound absorbing material 235 absorbs sound by transfer of the kinetic energy of the particles of air in which the generated sound waves are carried to thermal energy of the particles in the sound absorbing material. The remaining kinetic energy in the sound wave that is not transferred into thermal energy is reflected back from the sound absorbing material 235 in a sound wave. In this way, the sound waves are attenuated. The sound waves reflected from the areas of the sound absorbing material 235 exposed through the apertures may then leave the conduit 200 or be further incident on other areas of the sound absorbing material 235 through another aperture. Each time a sound wave is incident on an area of the sound absorbing material 235 exposed through an aperture in the inner wall 205, some of the kinetic energy of the particles of the medium in which the sound waves travels is transferred to thermal energy of the particles of the sound absorbing material 235. Therefore, a single sound wave may be attenuated multiple times before it leaves the conduit 200.

[0064] Figure 5 is a schematic of a fan assembly 300 according to an aspect of the invention. The fan assembly 300 includes the fan 100 of Figure 1 and a hose 170. The hose 170 is attached at a first end 171 of the hose 170 to the second end 207 of the conduit 200. Therefore, the hose 170 is connected to the fan 100 by the conduit 200 which functions as a connector between the two. When the hose 170 is connected to the conduit 200, air flow from the impeller 130 passes through the outlet 140, along the air passage 215 and along the hose 170 from the first end 171 to the second end 172. The generated sound waves also travel through the outlet 140, along the air passage 215 and along the hose 170 from the first end 171 to the second 172. However, the amplitude of the generated sound waves before the conduit 200 is at least 50% greater than the amplitude of the generated sound waves after the conduit 200, in the hose 170. The second end 172 of the hose 200 may be connected to a medical device such as a patient temperature control blanket or gown (not illustrated).

[0065] The conduit 200 in Figures 1 and 5 is shown as a component part attached to housing 110 of the fan 100. However, it will be appreciated that the conduit 200 could be positioned at the outlet 140 in the outlet-forming portion 112 of the housing 110. In this case, the first end 171 of the hose 170 is directly connected to the outlet 140.

[0066] Figure 6 is a schematic of a side view of a conduit 400 according to an aspect of the invention. Figure 7 is a cross section along the B-B' direction of a schematic of the conduit 400 according to an aspect of the invention. Figure 8 is an end view of a schematic of the conduit 400 according to an aspect of the invention. The conduit 400 may be used in the fan 100 instead of the conduit 200. The conduit 400 has a sound absorbing material 435 formed on the inner surface of an outer wall 445 of the conduit 400. The conduit 400 does not have a separate inner wall.

[0067] The conduit 400 is cylindrical, where the sound absorbing material 435 forms a cylinder having a smaller radius that the radius of the outer wall 445, which is also a cylinder. The sound absorbing material 435 defines the air passage 415 through which the sound waves travel and the air flows. The conduit 400 extends from a first end 406 to the second end 407 in the axial direction 141.

[0068] When the generated sound waves pass through the air passage 415, they do not all pass straight through the air passage 415 linearly in the direction indicated by the arrow 141. The majority of the generated sound waves are incident on the sound absorbing material 435 in multiple directions. The sound absorbing material 435 absorbs sound by transfer of the kinetic energy of the particles of air in which the generated sound waves are carried to thermal energy of the particles in the sound absorbing material. The remaining kinetic energy in the sound wave that is not transferred into thermal energy is reflected back from the sound absorbing material 435 in a sound wave. In this way, the sound waves are attenuated. The sound waves may then leave the conduit 400 or be further incident on other areas of the sound absorbing material 435. Each time a sound wave is incident on an area of the sound absorbing material 435, some of the kinetic energy of the particles of the medium in which the sound waves travels is transferred to thermal energy of the particles of the sound absorbing material 435. Therefore, a single sound wave may be attenuated multiple times before it leaves the conduit 400.

[0069] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to and do not exclude other components, integers, or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0070] Features, integers, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A fan (100) comprising: a housing (110) defining an inner region (120); an inlet (130) for receiving an air flow; an outlet (140) for expelling the air flow; an impeller (150) having a plurality of fan blades (160) that generate sound pressure waves within the inner region (120) on operation of the fan (100); and a conduit (200, 400) configured to attenuate the generated sound waves that travel through the outlet (140) such that an attenuation of the sound waves is at least 50%, the conduit (200, 400) comprising: an outer wall (245, 445) surrounding an air passage (215, 415) along which the air flow is caused to flow on operation of the fan (100); and a sound absorbing material (235, 435) provided between the air passage (215, 415) and the outer wall (245, 445).

2. The fan (100) according to claim 1, wherein the conduit (200) comprises an inner wall (205) defining a plurality of apertures (225a, 225b, 225c) therein, and wherein the sound absorbing material (235) is provided between the inner wall (205) and the outer wall (245).

3. The fan (100) according to claim 2, wherein the inner wall (205) is formed of a reflective material.

4. The fan (100) according to any of the preceding claims, wherein the conduit (200, 400) is provided at the outlet (140).

5. The fan (100) according to any of the preceding claims, wherein the conduit (200, 400) is provided in a component part that is connected to the housing (110).

6. The fan (100) according to any of the preceding claims, wherein the sound absorbing material (235, 435) has a sound absorbing coefficient of at least 0.5.

7. The fan (100) according to any of the preceding claims, wherein the sound absorbing material (235, 435) is selected from at least one of a foam, a mineral wool, or a combination of the two.

8. A fan assembly (300) comprising a fan (100) according to any of claims 1 to 7 and a hose (170) connected to the fan outlet (140).

9. The fan assembly (300) of claim 8 when dependent on claim 5 or any claim dependent thereon, wherein the component part is configured to connect the hose (170) to the fan outlet (140).

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