Dishwasher pump apparatus with a sound absorbing layer   

The present invention relates generally to dishwasher pump apparatus, and more particularly, to dishwasher pump apparatus including a sound absorbing layer.

Conventional dishwashers frequently include a motor cavity located underneath a wash tub. Components located within the motor cavity typically produce sound that may pass to the surrounding environment. One such component can comprise a dishwasher pump apparatus. While a dishwasher pump apparatus can be effective to facilitate dishwasher operation, there is a need to reduce sound typically produced by the dishwasher pump apparatus.

The following presents a simplified summary of the invention in order to provide a basic understanding of some example aspects of the invention. This summary is not an extensive overview of the invention. Moreover, this summary is not intended to identify critical elements of the invention nor delineate the scope of the invention. The sole purpose of the summary is to present some concepts of the invention in simplified form as a prelude to the more detailed description that is presented later.

In accordance with one aspect of the present invention, a dishwasher pump apparatus includes a liquid pump member, a motor operably connected to the liquid pump member, a cooling fan configured to cool the motor and an outer sound absorbing layer. The motor includes an outer motor housing and the cooling fan includes an outer fan housing. The outer sound absorbing layer at least partially encapsulates at least one of the outer motor housing and the outer fan housing.

In accordance with another aspect of the present invention, a dishwasher pump apparatus includes a liquid pump member, a motor operably connected to the liquid pump member and a cooling fan configured to cool the motor. The cooling fan includes an outer fan housing with an exhaust portion defining an exhaust path. The dishwasher pump apparatus further includes an inner sound absorbing layer lining an inner area of the exhaust portion.

In accordance with still another aspect of the present invention, a dishwasher pump apparatus includes a liquid pump member, a motor operably connected to the liquid pump member, a cooling fan configured to cool the motor and an outer sound absorbing layer. The motor includes an outer motor housing and the cooling fan includes an outer fan housing. The outer fan housing includes an exhaust portion defining an exhaust path. The outer sound absorbing layer at least partially encapsulates the outer motor housing and the outer fan housing.

The foregoing and other aspects of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a dishwasher including an example dishwasher pump apparatus in accordance with example aspects of the present invention;

FIG. 2 is a rear perspective view of portions of the dishwasher and dishwasher pump apparatus of FIG. 1;

FIG. 3 is a side view of portions of the dishwasher and dishwasher pump apparatus of FIG. 1 including an outer motor housing and an outer fan housing being at least partially encapsulated by an outer sound absorbing layer;

FIG. 4 depicts the side view of the dishwasher pump apparatus of FIG. 3 with a portion of the outer sound absorbing layer being removed to illustrate a side member of the underlying outer fan housing;

FIG. 5 depicts the side view of the dishwasher pump apparatus of FIG. 4 with the side member being removed to illustrate an exhaust path and a fan blade rotor of the cooling fan;

FIG. 6 depicts an inner surface of the side member of the outer fan housing;

FIG. 7 is a sectional view of the dishwasher pump apparatus along line 7-7 of FIG. 3;

FIG. 8 is a partial sectional view of the dishwasher pump apparatus along line 8-8 of FIG. 3; and

FIG. 9 is an enlarged view of portions of the sectional view of the dishwasher pump apparatus taken at view 9 of FIG. 8.

Example embodiments that incorporate one or more aspects of the present invention are described and illustrated in the drawings. These illustrated examples are not intended to be a limitation on the present invention. For example, one or more aspects of the present invention can be utilized in other embodiments and even other types of devices. Moreover, certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. Still further, in the drawings, the same reference numerals are employed for designating the same elements. The drawings can further include portions illustrated in somewhat schematic form.

FIG. 1 depicts one example of a dishwasher 10 incorporating a dishwasher pump apparatus 200 in accordance with aspects of the present invention. Dishwasher 10 may include a wash tub 20 configured to receive a wide range of articles for conducting a dishwasher operation. For example, the wash tub 20 may be designed to receive and support articles such as pots, pans, plates, bowls, utensils (e.g., knives, forks, spoons, spatulas, ladles, etc.), glassware, drinking vessels (e.g., cups, mugs, glasses, stemware, etc.) or the like. As shown in the broken away portion in FIG. 1, for example, the dishwasher 10 may include an inner area 16 configured to receive and support one or more articles, for example, as discussed above. In one example, a dishwasher rack 18 may be positioned within the inner area to receive articles such as the illustrated cup 19.

Various wash tubs 20 may be used in accordance with aspects of the present invention. In the illustrated example, the wash tub 20 comprises a side loading tub arrangement although top loading or other arrangements may be incorporated in further examples. The tub 20 can comprise a variety of materials such as plastic, metal, or other material types. The tub 20 includes an opening that may be provided with a closure, such as a dishwasher door 12. The dishwasher door 12 can be designed to pivot from the closed orientation illustrated in FIG. 1 to an open orientation (not shown) by grasping a handle and pivoting the dishwasher door 12 in direction 13 about a pivot axis 14.

The dishwasher 10 can also include a motor cavity 40 configured to receive one or more dishwasher components therein. For example, the motor cavity 40 can be configured to at least partially receive circulation motors, fluid input motors, or other motors. As shown in FIG. 1, a drain motor 50 may be positioned within the motor cavity 40. The motor cavity 40 can be defined at one or more various locations of the dishwasher 10. For example, the motor cavity may be located above, behind, at a side or other locations of the dishwasher. As shown, the motor cavity 40 can be located at least partially beneath the wash tub 20 of the dishwasher 10.

The dishwasher 10 can be configured to rest on a support surface, such as the floor of a room. In further examples, the dishwasher 10 can be supported by other support surfaces such as a shelf, table top, portion of a cabinet, surface of another appliance, or the like. As shown in FIG. 1, it will be appreciated that the motor cavity 40 can be at least partially positioned between a portion of the wash tub 20 and the support surface. In addition, or alternatively, the motor cavity 40 may be positioned at one or more other alternative locations in further examples.

The motor cavity 40 can be provided in a wide variety of ways. For instance, the dishwasher 10 can include a frame 30 configured to support the wash tub 20 to help define the motor cavity. Indeed, the frame 30 is configured to support the wash tub 20 at an elevated position with respect to the support surface to define the motor cavity 40 underneath the wash tub 20. The motor cavity 40 can provide room for the drain motor 50, the dishwasher pump apparatus 200 and/or other components of the dishwasher 10. In addition, or alternatively, the frame 30 can also be configured to support the dishwasher door 12 relative to the wash tub 20. In such examples, the frame 30 can be designed to withstand forces applied by the wash tub 20 and/or the dishwasher door 12. The frame 30, if provided, can be fabricated from various materials capable of supporting components of the dishwasher 10. For example, the frame 30 may be comprise of metal, plastic, ceramic, composite, and/or other material sufficient to provide support for the wash tub 20 and/or the dishwasher door 12.

Dishwasher 10 can further include a cover member 60 configured to substantially cover an access opening 42 into the motor cavity 40. The cover member 60 can be configured to be removably attached with respect to the frame 30 and/or other components of the dishwasher 10 to permit selective access to the motor cavity 40 by way of the access opening 42. Access to the motor cavity may be desirable to clean the support surface underlying the dishwasher 10 can also facilitate servicing of the dishwasher components located within the motor cavity 40. Various structures may be provided to permit selective removal of the cover member 60. It is still further contemplated that the cover member 60 may be designed to permanently seal off the access opening in still further examples.

As further illustrated, the dishwasher 10 can further include an optional sound absorbing device 70. The sound absorbing device 70 can include a sound absorbing element 80 configured to absorb sound originating from components within the motor cavity 40 from being emitted through the cover member 60. In one example, the sound absorbing element 80 can comprise an acoustical insulation blanket that may be formed from an acoustical insulating mat formed from a fibrous material. In one example, the fibrous material can comprise fibrous polyester configured to provide sound-absorbing properties. Although a wide range of materials may be used, one type of sound absorbing element 80 can comprise a VersaMat® acoustical insulation blanket sold by Owens Corning.

As further shown, the sound absorbing element 80 can include an acoustical insulation blanket with a first side attached to the cover member 60. Adhesive strip, hook and loop type fastener or other mechanical fastening apparatus may be used to provide removable attachment of the sound absorbing element to the cover member 60. The sound absorbing element 80 may also include a wide variety of shapes and sizes depending on the particular application. For example, the sound absorbing element 80 may have cut out areas configured to provide significant coverage over the cover member 60 while providing clearance for frame or other components of the dishwasher 10.

The sound absorbing device 70, if provided, can further include a motor guard 150. The motor guard 150 can be designed to thermally shield the sound absorbing element 80 from the drain motor 50. Thus, the motor guard 150 can help protect the sound absorbing element from thermal damage due to heat from the drain motor 50. In addition, or alternatively, the motor guard 150 can provide a dielectric shield between the drain motor 50 and the sound absorbing element 80. Thus, the motor guard 150 can act to inhibit, such as prevent, electrical current from passing from the drain motor to the sound absorbing element 80. Still further, the motor guard 150 can be configured to transmit vibrational energy from the drain motor 50 to the sound absorbing element 80. For example, the drain motor 50 may engage the motor guard 150 such that vibrational energy from the drain motor 50 is transmitted through the motor guard 150 to the sound absorbing element 80. Once transmitted, the sound absorbing element 80 can absorb the vibrational energy, thereby inhibiting release of sound from the motor cavity 40.

The motor guard 150 can be fabricated from a wide range of materials, sizes and/or configurations to provide the desired thermal shielding, dielectric shielding and/or noise transmission characteristics. In one example, the motor guard 150 can comprise a talc filled copolymer polypropylene although other material types may be used in further examples. The talc filled copolymer polypropylene or other material can be formed as a substantially rigid material with a density of approximately 1.39 g/cm3, although other material characteristics may be provided in further examples.

The motor guard 150 can be attached to the second side of the sound absorbing element 80 an adhesive, mechanical fastener or other attachment mechanism. As shown, the motor guard 150 can also be attached such that a portion of the motor guard 150 is positioned between a portion of the drain motor 50 and a portion of the sound absorbing element 80. As further shown in the drawings, a portion of the sound absorbing element 80 can be positioned between a portion of the cover member 60 and the motor guard 150.

The motor guard 150 can cover an area of the second side of the sound absorbing element 80 (e.g., acoustical insulation blanket). In one example, the motor guard 150 can be configured to cover less than the entire area of the second side of the acoustical insulation blanket. For instance, the motor guard 150 can be designed to substantially cover less than about 75% of the area of the acoustical insulation blanket. In further examples, the motor guard 150 can be designed to substantially cover less than about 50% of the area of the acoustical insulation blanket. In still further examples, the motor guard 150 can be designed to substantially cover less than about 25% of the area of the acoustical insulation blanket. In still further examples, the motor guard 150 can be designed to substantially cover about 20% of the area of the acoustical insulation blanket. Reducing the coverage of the motor guard over the second area can reduce the material costs of the motor guard 150 while still providing desirable thermal shielding, dielectric shielding and/or noise transmission characteristics.

As discussed previously, the dishwasher 10 can further provide the dishwasher pump apparatus 200 in the motor cavity 40. It will be appreciated that the dishwasher pump apparatus 200 may be located at least partially or entirely outside of the motor cavity 40 in further examples.

FIGS. 2-9 illustrate features of the dishwasher pump apparatus 200 in accordance with examples of the present invention. The dishwasher pump apparatus 200 is configured to pump liquid during a dishwasher operation. For example, the dishwasher pump apparatus 200 can comprise a circulation pump configured to pump liquid to a rotating spray arm or other dispensing devices positioned in the inner area 16 of the dishwasher 10. The dishwasher pump apparatus 200 can be designed to pump liquid during a washing cycle, rinsing cycle, or other dishwasher operation.

FIG. 8 is a partial sectional view of the dishwasher pump apparatus 200 in somewhat schematic form. As shown in FIG. 8, the dishwasher pump apparatus 200 includes a liquid pump member 210. The illustrated liquid pump member 210 comprises a pump rotor 211 that may cooperate with housing portions to form a circulation path. The circulation path may be formed entirely by the dishwasher pump apparatus 200 or may at least partially be formed by portions of the wash tub 20 after connecting the dishwasher pump apparatus 200 to the tub 20. For example, as shown in FIG. 8, the dishwasher pump apparatus 200 can include a coupling structure 202 with a pair of O-ring liquid seals 204a, 204b and a stop flange 206 extending adjacent a mounting groove 208. As shown in FIG. 2, the dishwasher pump apparatus 200 can be installed by inserting the pump rotor 211 into an interior area of a circulation pump housing 24 integrally formed with a sump 22 of the wash tub 20. The pump rotor 211 is inserted until the O-ring liquid seals 204a, 204b provide a fluid tight seal between the circulation pump housing 24 and the dishwasher pump apparatus 200. A mounting bracket 26 can then be used to engage mounting grooves 208. Once secured, the mounting bracket 26 maintains the fluid tight connection between the dishwasher pump apparatus 200 and the circulation pump housing 24. Thus, as shown in FIG. 2, structures of the dishwasher 10 and dishwasher pump apparatus 200 allow the dishwasher pump apparatus 200 to be operatively connected to the inner area 16 of the dishwasher 10.

The dishwasher pump apparatus 200 can further include a motor 220 operably connected to the liquid pump member 210. Various motors can be used in accordance with aspects of the present invention. For example, as shown in FIGS. 8 and 9, the motor 220 can include an electric motor comprising a first motor portion 220a and a second motor portion 220b. The first motor portion 220a can include a magnet 221 secured to a first outer motor housing portion 224a and a rotor 222 secured to a drive shaft 212. The second motor portion 220b can include a pair of graphite brush members 225 that are each movably mounted within a respective sleeve 226. Respective springs 227 can bias end portions 225a of the respective graphite brush members 225 to engage corresponding electrical contacts 228 of a commutator 229 attached to the drive shaft 212. The graphite brush members 225 can each include a beveled portion 225b designed to reduce the area of the end portion 225a engaging the electrical contacts 228. Reducing the area of the end portions 225a can be beneficial to reduce the motor noise produced by the engagement between the end portions 225a and the respective electrical contacts 228 as the drive shaft 212 rotates.

As shown in FIG. 8, the drive shaft 212 operably connects the motor 220 to the liquid pump member 210 to allow rotational energy to be transmitted from the motor 220 to the pump rotor 211 of the liquid pump member 210. In operation, the motor 220 can provide the power source to permit the liquid pump member 210 to work the liquid when circulation is desired. As further shown in FIG. 8, in some examples, the motor 220 can include an outer motor housing 224 configured to house at least a portion of one or more motor components. For example, the first motor portion 220a can include the first outer motor housing portion 224a configured to house the magnet 221 and rotor 222 of the first motor portion 220a. As further shown, the second motor portion 220b can include a second outer motor housing portion 224b configured to house the graphite brush members 225 and commutator 229 of the second motor portion 220b. The outer motor housing 224 can be configured to protect the motor components from being damaged during handling and/or other contact the might otherwise occur. In addition or alternatively, the outer motor housing 224 may help electrically and/or thermally insulate the motor components from the surrounding environment. The outer motor housing 224 can comprise various materials such as a polymeric material, metal, resin, composite or combination thereof or other materials suitable for housing motor components.

The dishwasher pump apparatus 200 can further include a cooling fan 230 configured to cool the motor 220. The cooling fan 230 can include a tangential fan rotor 232 configured to draw air through an interior area of the dishwasher pump apparatus 200. In further examples, a centrifugal fan rotor, an axial fan rotor or other types of fan components may be used to produce the desired air flow. The cooling fan 230 can receive power in a wide variety of ways. For example, the cooling fan 230 may be powered by an independent source. In further examples, as shown, the motor 220 can be further operably connected to the fan rotor 232. For instance, as shown in FIG. 8, the drive shaft 212 further operably connects the motor 220 to the fan rotor 232 to allow rotational energy to be transmitted from the motor 220 to the fan rotor 232. In the illustrated embodiment, therefore, the motor 220 simultaneously powers both the liquid pump member 210 and the cooling fan 230 by way of the common drive shaft 212.

The cooling fan 230 can further include an outer fan housing 240 configured to house at least a portion of the fan rotor 232 and/or at least partially define an exhaust path 250. For instance, the outer fan housing 240 can be configured to protect the fan rotor 232 from being damaged during handling and/or other contact might otherwise occur with the fan rotor 232. As shown in FIG. 8, the outer fan housing 240 can comprise a shroud 241 including a circumferential portion 242 and a side portion 245 that cooperate to at least partially shroud the fan rotor 232.

In addition or alternatively, at least a portion of the outer fan housing 240 may be configured to define an exhaust path. For example, as shown in FIGS. 4-7, the outer fan housing 240 includes an exhaust portion 246 that at least partially defines an exhaust path 250. The exhaust portion 246 can be formed by various structural arrangements. For example, the exhaust portion 246 can include first and second opposed walls 246a, 246b attached to third and fourth opposed walls 246c, 246d. The walls can be integrally formed together or may be formed separately and then attached together. In the illustrated embodiment, the second, third and forth walls 246b, 246c, 246d are integrally formed together and the first wall 246a is configured to be subsequently attached to the third and fourth walls 246c, 246d. The exhaust portion 246 of the outer fan housing 240 can further define an exhaust port 252 in fluid communication with the exhaust path 250.

The exhaust path 250 can include various profiles in accordance with aspects of the present invention. In one example, the exhaust path can extend along a linear path or a curved path. As shown, in one example, the exhaust path 250 can comprise a serpentine-shaped exhaust path 250.

As shown in FIGS. 4 and 6, the outer fan housing 240 can also include a side member 244 including the first wall 246a of the exhaust portion 246 and the side portion 245 of the shroud 241. The side member 244 is configured to be subsequently attached to other portions of the outer fan housing 240 to facilitate assembly of the dishwasher pump apparatus 200. For example, as shown in FIG. 5, prior to installation of the side member 244, areas of the exhaust path 250 and the fan rotor 232 can be exposed. At the appropriate time, the side member 244 may be installed to conceal these areas. The outer fan housing 240 can comprise various materials such as a polymeric material, metal, resin, composite or combination thereof or other materials suitable for housing the fan rotor 232.

In further examples, the dishwasher pump apparatus 200 can include an optional outer sound absorbing layer 270 that at least partially encapsulates at least one of the outer motor housing 224 and the outer fan housing 240. In one example, the outer sound absorbing layer 270 only at least partially encapsulates the outer motor housing 224. In another example, the outer sound absorbing layer 270 only at least partially encapsulates the outer fan housing 240. As shown in the illustrated embodiment, the outer sound absorbing layer 270 at least partially encapsulates the outer motor housing 224 and the outer fan housing 240. Still further, the outer sound absorbing layer 270 can at least partially encapsulate other portions of the dishwasher pump apparatus.

The outer sound absorbing layer 270 can at least partially encapsulate the outer motor housing 224. For example, as shown in FIGS. 2 and 8, the outer sound absorbing layer 270 can include a first portion 272 at least partially encapsulating the first outer motor housing portion 224a. The first portion 272 of the sound absorbing layer 270 can extend around a part of the first outer motor housing portion 224a or entirely circumscribe the first outer motor housing portion 224a. In the illustrated example, the first portion 272 entirely circumscribes the first outer motor housing 224a. In addition or alternatively, the first portion 272 can partially or entirely circumscribe the magnet 221 and rotor 222 of the first motor portion 220a. In the illustrated example, the first portion 272 entirely circumscribes the magnet 221 and rotor 222 of the first motor portion 220a.

As further shown in FIGS. 2 and 8, the outer sound absorbing layer 270 can include a second portion 274 at least partially encapsulating the second outer motor housing portion 224b. The second portion 274 of the sound absorbing layer 270 can extend around a part of the second outer motor housing portion 224b or entirely circumscribe the second outer motor housing portion 224b. In the illustrated example, the second portion 274 entirely circumscribes the second outer motor housing 224b. In addition or alternatively, the second portion 274 can partially or entirely circumscribe the graphite brush members 225 and the commutator 229. In the illustrated example, the second portion 274 entirely circumscribes the graphite brush members 225 and the commutator 229 of the second motor portion 220b.

The outer sound absorbing layer 270 can at least partially encapsulate the outer fan housing 240 with a third portion 276 and/or a fourth portion 278. For example, the third portion 276 of the sound absorbing layer 270 can at least partially or entirely encapsulate the shroud 241 of the outer fan housing 240. Indeed, as shown in FIGS. 3 and 8, the third portion 274 entirely encapsulates the circumferential portion 242 and the side portion 245 of the shroud 241. In addition or alternatively, a fourth portion 278 can at least partially or entirely encapsulate the exhaust portion 246 of the outer fan housing 240. Indeed, as shown in FIGS. 2, 3 and 7, the fourth portion 278 entirely encapsulates the first, second, third and fourth walls 246a, 246b, 246c, 246d of the exhaust portion 246. The fourth portion 278 can also partially or entirely circumscribe the exhaust path 250 defined by the exhaust portion 246. For example, as shown in FIG. 7, the fourth portion 278 entirely circumscribes a portion of the exhaust path 250.

In further examples, the dishwasher pump apparatus 200 can include an optional inner sound absorbing layer 280 lining an inner area of the exhaust portion 246 of the outer fan housing 240. As shown in FIG. 5, the inner sound absorbing layer 280 can extend from the exhaust port 252 in a direction upstream along the exhaust path 250. Although not shown, further examples may place the sound absorbing layer 280 in other portions of the exhaust portion 246. For example, the inner sound absorbing layer may extend from a position spaced away from the exhaust port 252 in a direction upstream along the exhaust path.

The inner sound absorbing layer 280 can also circumscribe the exhaust path 250 although the sound absorbing layer 280 may only partially extend around the exhaust path 250 in further examples. For instance, as shown in FIG. 7, the inner sound absorbing layer 280 can include a first portion 280a lining an inner area of the first wall 246a of the exhaust portion 246 and a second portion 280b lining an inner area of the second wall 246b of the exhaust portion 246. Likewise, the inner sound absorbing layer 280 can include a third portion 280c lining an inner area of the third wall 246c of the exhaust portion 246 and a fourth portion 280d lining an inner area of the fourth wall 246d of the exhaust portion 246. It will be appreciated that the inner sound absorbing layer 280 can be designed to absorb sound from the outlet air stream 262d as the outlet air stream passes through the exhaust path 250 prior to exiting the exhaust port 252.

The outer and/or inner sound absorbing layers 270, 280 can comprise a wide variety of materials configured to absorb sound energy such as fibers or other insulation. In one example, one or both of the sound absorbing layers 270, 280 comprise a porous material. In one example, an open-cell foam and/or closed-cell foam may be used. In one example, an open-cell rubber, closed-cell rubber or other elastomeric and/or polymeric material may be used. Furthermore various porosity sizes may be used in accordance with different aspects of the present invention. In one example, the outer and inner sound absorbing layers both comprise a porous material wherein the average pore size of the inner sound absorbing layer is larger than the average pore size of the outer sound absorbing layer. In one example, at least one of the sound absorbing layers can comprise a chloroprene rubber, flexible closed-cell foam furnished in sheets or blocks having a density range of 0.13-0.23 g/cm3 available as type C-4305(x) from Inoac Corp of Japan.

The inner and/or outer layer of sound absorbing material may be attached in a variety of ways to the housings. For example, as shown, the sound absorbing material may be cut in sheets and adhered with adhesive to the outer surface and/or inner surfaces of the housing portions. Various adhesives, epoxy or other attachment mechanisms may be used in accordance with the present invention.

One example method of operating the dishwasher pump apparatus 200 will now be described. During a dishwasher operation, the motor 220 is energized. The motor rotates the drive shaft 212 which in turn rotates the pump rotor 211 of the liquid pump member 210. The liquid pump of the dishwasher 10 can then circulate liquid within the inner area 16 of the dishwasher to perform the dishwasher operation. Rotation of the drive shaft 212 also simultaneously rotates the fan rotor 232 of the cooling fan 230. As shown in FIGS. 2 and 8, the rotating fan rotor 232 causes an inlet air stream 262a to enter an inlet port 260 of the dishwasher pump apparatus 200. As apparent in FIG. 8, the air stream passes through the first motor portion 220a (see reference number 262b) to cool the first motor portion 220a. Next, the air stream passes through the second motor portion 220b (see reference number 262c) to cool the second motor portion 220b. Once the air stream has passed through the motor 220, an exhaust air stream 262d passes along the exhaust path 250 from the motor 220. The exhaust air stream 262d then passes exits the dishwasher pump apparatus 200 by passing through the exhaust port 252. It will be appreciated that noise may be carried by the air stream as it passes through the pump 220. Such noise can be absorbed by the inner sound absorbing layer 280 prior to exiting the exhaust port 252. Moreover, noise passing through the outer motor housing 224 and/or the outer fan housing, can be absorbed by the outer sound absorbing layer 270.

The invention has been described with reference to the example embodiments described above. Modifications and alterations will occur to others upon a reading and understanding of this specification. Examples embodiments incorporating one or more aspects of the invention are intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.