Patent Description:
Blowers generally include two main parts: a rotating part, namely an impeller and shaft; and a stationary part that defines a fluid flow path, typically a chamber such as a volute.

Bearings are usually employed in pairs and in coaxial arrangements to support the rotating part, e.g., shaft. Ideally, the two bearings are located by a stationary member that constrains the two bearings in perfect axial alignment. Real world designs are less than perfect and, therefore, compromise bearing performance.

A widely employed bearing suspension mode involves holding each bearing within a separate housing structure and fitting those housing structures together to approximate a coaxial bearing arrangement.

There are two main classes of constraints on the packaging of bearings. One constraint relates to the practical limits of manufacturing precision, and another constraint relates to the need to attach and efficiently package items that must or are intended to rotate.

With respect to the first constraint, although the precision of part forming technologies improves continuously, the state of the art is far from perfect. Furthermore, increased precision usually translates to greater expense, often dissuading a manufacturer from embracing the state of the art processes.

The second constraint is driven by the need to place items (such as a rotor/stator) between bearing pairs. This typically leads to the use of a two part housing construction. A consequence of multipart housings is that they accumulate unwanted tolerance build-up at each faying or joint surface, and, as such, each component part must be, or is ideally, precisely shaped so that the accumulated dimensional errors remain within acceptable range.

<CIT> describes a blower being supported within an outer casing by a support system, wherein the support system includes a side support, a top support, or a bottom support or combinations thereof, and the bottom support includes a leaf spring and a conducting member.

The inventors of the present invention have devised an improved arrangement that does not suffer from the above-mentioned drawbacks.

The present invention is realised with a positive pressure airway device according to claim <NUM>.

Preferred embodiments are the subject matter of dependent claims <NUM> to <NUM>.

Some preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:.

The following description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment may be combinable with one or more features of the other embodiments as long as they fall within the scope of the invention which is solely defined by the appended claims.

Also, while each blower embodiment below is described as including two stages, it should be appreciated that each embodiment may a single stage design or other multiple stage designs, e.g., three, four, or more stages.

In this specification, the words "air pump" and "blower" may be used interchangeably. In this specification, the phrase "stationary part" may be taken to include "volute". The term "air" may be taken to include breathable gases, for example air with supplemental oxygen. It is also acknowledged that the blowers described herein may be designed to pump fluids other than air.

<FIG> to <FIG> illustrate a blower <NUM> which can be used in an embodiment of the present invention. As illustrated, the blower <NUM> includes two stages with two corresponding impellers <NUM>, <NUM>. In this embodiment, one impeller <NUM> is positioned on one side of the motor <NUM> and the other impeller <NUM> is positioned on the other side of the motor <NUM>. However, other suitable impeller arrangements are possible, e.g., two impellers positioned on the same side of the motor. Also, the blower <NUM> may include a single stage design or other multiple stage designs, e.g., two or more impellers.

A stationary portion of the blower <NUM> includes a housing <NUM> with first and second housing parts <NUM>, <NUM>, a stator component <NUM> including stator vanes <NUM>, and first and second shields <NUM>, <NUM>. A rotating portion of the blower <NUM> includes a rotatable shaft or rotor <NUM> adapted to be driven by motor <NUM> and first and second impellers <NUM>, <NUM> provided to end portions of the shaft <NUM>. The motor <NUM> includes a magnet <NUM> (e.g., two pole magnet) provided to shaft <NUM> and a stator assembly <NUM> to cause spinning movement of the shaft <NUM> via the magnet <NUM>. In an embodiment, the motor may be operated without the use of rotor position sensors, e.g., no Hall sensors on printed circuit board (PCB), which may reduce the number of wires, e.g., <NUM> wires.

The stator assembly <NUM> includes windings <NUM> and a stator or stator lamination stack <NUM> (e.g., slotless or toothless) provided to the windings <NUM>. Further details of coil winding is disclosed in <CIT>, which is incorporated herein by reference in its entirety.

The blower <NUM> is generally cylindrical and has an inlet <NUM> provided by the first housing part <NUM> at one end and an outlet <NUM> provided by the second housing part <NUM> at the other end. The blower <NUM> is operable to draw a supply of gas into the housing <NUM> through the inlet <NUM> and provide a pressurized flow of gas at the outlet <NUM>.

The blower <NUM> has axial symmetry with both the inlet <NUM> and outlet <NUM> aligned with an axis <NUM> of the blower <NUM>. In use, gas enters the blower <NUM> axially at one end and leaves the blower <NUM> axially at the other end. Such arrangement may provide relatively low noise in use, e.g., due to axial symmetry and/or low volute turbulence. Exemplary embodiments of such blowers are disclosed in PCT Application No.<CIT>, which is incorporated herein by reference in its entirety.

In an embodiment, the blower <NUM> may be relatively compact and have an overall diameter D of about <NUM>-<NUM>, e.g., <NUM>, and an overall length L of about <NUM>-<NUM>, e.g., <NUM>. However, other suitable sizes are possible.

As shown in <FIG> and <FIG>, the stator component <NUM> includes a base <NUM>, an annular flange <NUM> extending from the base <NUM>, a tube or bearing tube <NUM>, and a plurality of stator vanes <NUM>. In the illustrated embodiment, the stator component <NUM> is integrally formed (e.g., injection molded of plastic material) as a one-piece structure. However, the stator component <NUM> may be constructed in other suitable manners.

As best shown in <FIG>, the annular flange <NUM> is sandwiched between the first and second housing parts <NUM>, <NUM> to support the stator component <NUM> within the housing <NUM>.

The plurality of stator vanes <NUM>, e.g., between <NUM> and <NUM> stator vanes, are structured to direct airflow towards an orifice <NUM> in the base <NUM>. In the illustrated embodiment, the stator component <NUM> has six stator vanes <NUM>. Each vane <NUM> is substantially identical and has a generally spiral shape. In addition, each vane <NUM> includes an inner portion <NUM> (adjacent the tube <NUM>) and an outer portion <NUM>. As best shown in <FIG>, the inner portion <NUM> is recessed (e.g., reduced in height) with respect to the outer portion <NUM>. However, the stator component may have other suitable structure to condition the airflow between stages.

The interior surface <NUM> of the tube <NUM> is structured to retain and align the bearings <NUM>, <NUM> that rotatably support the shaft <NUM>. In addition, the tube <NUM> encloses the magnet <NUM> on the shaft <NUM>, which is aligned in close proximity to the stator assembly <NUM> provided along an exterior surface <NUM> of the tube <NUM>. In the illustrated embodiment, the tube <NUM> has at least a portion that is sufficiently "magnetically transparent" to allow a magnetic field to pass through it, which allows the stator assembly <NUM> to act on the magnet <NUM> positioned within the tube <NUM> without significant loss of flux density and/or increased heat, if any. In an embodiment, such "magnetic transparency" may be provided by one or more of the tube's material properties, e.g., non-electrically conductive, non-magnetic, and/or thermally conductive. For example, the tube may include one or more of the following: anisotropic materials, composite (e.g., base polymers (e.g., LCP and PPS) with either ceramic fillers, graphite fillers, and/or other fillers), heterogeneous fill, insert molding, plating, ion implantation, etc. Alternatively, or in addition, such "magnetic transparency" may be provided by the tube's structural properties, e.g., one or more perforations, slits, etc. in the tube. It should be appreciated that the tube may include one or more of these properties and/or a sufficient degree of these properties to provide sufficient "magnetic transparency. " Further details of a magnetically transparent tube are disclosed in <CIT>, and <CIT>, each of which is incorporated herein by reference in its entirety.

In the illustrated embodiment, the tube has a circular cross-sectional configuration along its length. However, it should be appreciated that the tube may have other suitable shapes, e.g., square, polygonal, conical, etc. Also, the tube may include one or more parts, e.g., multi-part construction. In addition, the tube may have different material properties along its length or circumference, e.g., different levels or regions of "magnetic transparency", "non-electrical conductivity", and/or "thermal conductivity.

In the illustrated embodiment, the tube <NUM> is structured such that mixed bearing sizes may be used. As shown in <FIG>, the upper end of the tube <NUM> is structured to support bearing <NUM> and the lower end of the tube <NUM> is structured to support bearing <NUM> having a smaller size or diameter than bearing <NUM>.

Specifically, the upper end of the tube <NUM> includes an annular surface <NUM>(<NUM>) defining a diameter d1 and adapted to support bearing <NUM>. The lower end of the tube <NUM> includes an annular surface <NUM>(<NUM>) defining a smaller diameter d2 and adapted to support bearing <NUM>. As illustrated, the one-piece tube <NUM> provides accurate bore-to-bore alignment which provides accurate bearing-to-bearing alignment.

In an embodiment, the tube may be manufactured such that upper and lower ends of the tube are adapted to support bearings of the same size. However, a tube structured to support mixed bearing sizes may facilitate a line of draw molding process. Also, the tube may be structured to support one or more bearings, and the bearings may include other suitable configurations, e.g., fluid bearings. Further, in an embodiment, the tube may be structured such that the upper end of the tube is structured to support a bearing having a smaller size or diameter than the bearing supported at the lower end of the tube (e.g., blower with a larger inlet diameter to the second impeller).

A sloped surface <NUM>(<NUM>) may be provided between surfaces <NUM>(<NUM>) and <NUM>(<NUM>) to guide the shaft <NUM> (with bearings <NUM>, <NUM> provided to respective end portions) into the lower end of the tube <NUM>. For example, the smaller bearing side of the shaft <NUM> may be inserted into or "dropped into" the tube <NUM> through the upper end of the tube <NUM>. As the smaller bearing <NUM> approaches the lower end, the sloped surface <NUM>(<NUM>) will guide the bearing <NUM> into engagement with surface <NUM>(<NUM>) having a reduced diameter. Thus, the bearing <NUM> is self-guided into its operative position.

In the illustrated embodiment, the lower end of the tube <NUM> includes a flange <NUM> that provides a stop or support for the bearing <NUM> at the lower end. The upper end of the tube <NUM> is adapted to engage the shield or rotor cap <NUM>, which provides a stop for the bearing <NUM> at the upper end and hence retains the shaft <NUM> within the tube <NUM>.

Washers <NUM> and a spring or biasing element <NUM> may be provided between the bearing <NUM> and the rotor magnet <NUM> to maintain alignment of the rotor magnet <NUM> with the stator assembly <NUM> and/or provide a pre-load to the inner race of bearing <NUM>.

In an embodiment, end portions of the shaft <NUM> may include one or more bonding grooves for securing the bearings <NUM>, <NUM> in an operative position, and an intermediate portion of the shaft <NUM> may include one or more bonding grooves (e.g., helical bonding grooves) for securing the magnet <NUM> in an operative position. The bonding grooves may be provided to selected portions of the shaft (e.g., ends and middle of the shaft) or the bonding grooves may extend along the entire length of the shaft. In another embodiment, an intermediate portion of the shaft may include threads (e.g., extending outwardly from the exterior surface of the shaft) for securing the magnet in an operative position.

The stator assembly <NUM> is provided along the exterior surface <NUM> of the tube <NUM>. In addition, the stator component <NUM> and first shield <NUM> cooperate to support and maintain the stator assembly <NUM> in an operative position.

As illustrated, the windings <NUM> of the stator assembly <NUM> are encased or supported by the recessed, inner portion <NUM> of the stator vanes <NUM>, and the stack <NUM> of the stator assembly <NUM> is encased or supported by the outer portion <NUM> of the stator vanes <NUM>. In addition, the shield <NUM> includes an annular flange <NUM> that encloses an upper portion of the windings <NUM> and engages an upper side <NUM> or an exterior surface <NUM> of the stack <NUM> (e.g., left side of <FIG> shows flange <NUM> engaging upper side <NUM> of stack <NUM> and right side of <FIG> shows flange <NUM> engaging exterior surface <NUM> of stack <NUM>). The elongated portions of the annular flange <NUM> (i.e., the portions engaging exterior surface <NUM> of the stack <NUM>) are provided to accommodate tabs that engage the housing as described in greater detail below. Thus, the stator component <NUM> and shield <NUM> cooperate to enclose and sandwich the stator assembly <NUM>.

In the illustrated embodiment, the exterior surface <NUM> of the stack <NUM> and/or the annular flange <NUM> engaging the stack <NUM> is exposed to the flow of gas. This arrangement allows forced-convection cooling of the stack <NUM> as gas flows through the housing <NUM> in use. In addition, this arrangement may assist in heating the gas or patient air.

Further, the windings <NUM> of the stator assembly <NUM> are exposed to the flow of gas to allow cooling and assist in heating the gas or patient air.

In an embodiment, the stator component <NUM> and shield <NUM> may be thermally conductive (e.g., add graphite or other filler to polymer material) to help with heat conduction.

The first or upper shield <NUM> includes a disk portion <NUM> and the annular flange <NUM> extending from the outer edge of the disk portion <NUM> and adapted to engage the stator assembly <NUM> as described above. The outer edge of the disk portion <NUM> substantially aligns with or extends radially beyond the outer edge of the impeller <NUM>. The shield <NUM> provides a narrow annular gap <NUM> between the annular flange <NUM> and the side wall of the housing part <NUM>, which is sufficient to direct gas into the stator component <NUM>.

The disk portion <NUM> includes an opening <NUM> that allows the shaft <NUM> to extend therethrough. An annular flange or projection <NUM> is provided along the opening <NUM> that is structured to engage the upper end of the tube <NUM> of the stator component <NUM>, e.g., with a friction fit.

Also, the annular flange <NUM> includes one or more tabs <NUM> that are adapted to engage within respective slots <NUM> defined between the first housing part <NUM> and the stator component <NUM> (e.g., see <FIG> and <FIG>). As shown in <FIG>, the shield <NUM> includes three tabs <NUM> that are received in respective slots <NUM> defined between the first housing part <NUM> and the stator component <NUM>. However, any suitable number of slots/tabs may be provided. Also, it should be appreciated that the slots/tabs may be optional and the shield <NUM> may be supported within the housing in other suitable manners.

The second or lower shield <NUM> includes a plurality of stator vanes <NUM>, e.g., between <NUM> and <NUM> stator vanes, to direct airflow towards the outlet <NUM>. In the illustrated embodiment, the shield <NUM> has <NUM> stator vanes. Each vane <NUM> is substantially identical and has a generally spiral shape. In addition, each vane <NUM> includes an inner portion <NUM> (adjacent the hub <NUM>) and an outer portion <NUM>. As best shown in <FIG> and <FIG>, the outer portion <NUM> is recessed (e.g., reduced in height) with respect to the inner portion <NUM>, and a contoured edge <NUM> extends between the inner and outer portions <NUM>, <NUM>.

In the illustrated embodiment, the stator vanes <NUM> support the shield <NUM> within the second housing part <NUM> adjacent the outlet <NUM>. As illustrated, the contoured edge <NUM> of the shield <NUM> engages the edge of the outlet <NUM> to align the shield <NUM> with the outlet <NUM>. The hub <NUM> and inner portion <NUM> of the vanes <NUM> extend at least partially through the outlet <NUM> and the outer portion <NUM> of the vanes <NUM> engage the lower wall of the second housing part <NUM>. The hub <NUM> at the central portion of the shield <NUM> is shaped to direct the air flow down towards the outlet <NUM>.

In an embodiment, the shield <NUM> may include an inlet conduit <NUM> and an outlet conduit <NUM> (as indicated in dashed lines in <FIG>) to provide pressure balance across the bearings <NUM>, <NUM>. Specifically, the inlet and outlet conduits <NUM>, <NUM> provide a short circuit of pressure around the tube <NUM> and hence the bearings <NUM>, <NUM> to avoid such drying out or displacement of the bearings' <NUM>, <NUM> lubricant (e.g., air flow through the tube and through the interior of the bearings can dry out grease in the bearings and carry away heat from the bearings). That is, the inlet conduit <NUM> allows air to flow into the space between the shield <NUM> and the tube <NUM>, and the outlet conduit <NUM> allows air to flow out of the space. Such arrangement allows any pressure differential to bleed through the inlet and outlet conduits <NUM>, <NUM>, rather than travel through the tube <NUM> as described above.

In an alternative embodiment, as shown in <FIG>, grooves <NUM>, <NUM> may be provided along the shaft <NUM> to provide a short circuit of airflow or pressure around each of the bearings <NUM>, <NUM> to avoid drying out of the bearings. As illustrated, the grooves <NUM>, <NUM> are provided adjacent respective bearings <NUM>, <NUM> and allow air to flow through the grooves <NUM>, <NUM> rather than through respective bearings <NUM>, <NUM>, e.g., when air flows through the tube <NUM> due to pressure differential inside tube <NUM>. In an embodiment, one or more grooves may extend along the length of the shaft, rather than along selected portions as illustrated. Alternatively, the grooves <NUM>, <NUM> may be on the tube <NUM> adjacent the outside diameter of respective bearings <NUM>, <NUM>.

In the illustrated embodiment, each impeller <NUM>, <NUM> includes a plurality of continuously curved or straight blades <NUM> sandwiched between a pair of disk-like shrouds <NUM>, <NUM>. The shrouds may help to reduce tonal noise in use. The lower shroud <NUM> incorporates the hub or bushing <NUM> that is adapted to receive the shaft <NUM>. Also, each impeller <NUM>, <NUM> includes a tapered configuration wherein the blades <NUM> taper towards the outer edge. Further details of impellers are disclosed in PCT Application No. <CIT>, which is incorporated herein by reference in its entirety.

In an embodiment, each impeller may be constructed of glass reinforced polycarbonate. In another embodiment, each impeller may be constructed of glass reinforced liquid crystal polymer (LCP), e.g., Ticona Vectra-E130i. Glass reinforced LCP may improve acoustic dampening, especially with respect to reducing the tonal acoustic noise by reducing the impeller resonating. However, other suitable materials are possible.

In the first stage, air enters the blower <NUM> at the inlet <NUM> and passes into the first impeller <NUM> where it is accelerated tangentially and directed radially outward. It is noted that suction is developed at the inlet to draw air into the blower. Air then flows in a spiral manner with a large tangential velocity component and also an axial component passing through the gap <NUM><NUM> defined by the outer edge of the shield <NUM> and the side wall of housing part <NUM>. As noted above, air may bleed through the shield <NUM> (through the inlet and outlet conduits <NUM>, <NUM>) to provide pressure balance in use. Air then enters the stator vanes <NUM> formed in the stator component <NUM> and is directed radially inwardly towards orifice <NUM>, and thereafter onto the second stage.

In the second stage, air passes into the second impeller <NUM> where it is accelerated tangentially and directed radially outward. Air then flows in a spiral manner with a large tangential velocity component and also an axial component passing through the gap <NUM> defined by the outer edge of the shield <NUM> and the side wall of housing part <NUM>. Air then enters the stator vanes <NUM> formed in the shield <NUM> and is directed towards the outlet <NUM>.

In the illustrated embodiment, the airflow enters and exits each stage within the blower in a substantially axial direction. Consequently, the air enters the blower axially at one end, and leaves the blower axially at the other end. The axially symmetric blower provides balance, which leads to lower levels of blade pass tone, and lower levels of turbulence noise.

<FIG> illustrates another blower <NUM> which can be used in the present invention. The blower <NUM> is substantially similar to the blower <NUM> described above. In contrast, the upper impeller <NUM> has a mixed flow configuration and corresponding portions of the first housing part <NUM> and first shield <NUM> are tapered to match the mixed flow configuration of the upper impeller <NUM>.

As illustrated, each of the blades <NUM> of the impeller includes an end portion <NUM> that tapers toward the outer edge. In addition, the end portion <NUM> of each blade <NUM> is bent, angled, or sloped downwardly with respect to the hub <NUM>. For example, a longitudinal axis L of each end portion <NUM> may be bent or angled at an angle α with respect to an axis H of the hub <NUM>. Such angle α may be about <NUM>°-<NUM>°, e.g., <NUM>°. However, other suitable angles are possible depending on application.

The upper wall <NUM> of the first housing part <NUM> is tapered to match the mixed flow configuration of the impeller <NUM>, and the upper wall <NUM> of the shield <NUM> is tapered to match the mixed flow configuration of the impeller <NUM>.

<FIG> illustrates a another blower <NUM> which can be used in the present invention. Similar to the blowers <NUM>, <NUM> described above, the blower <NUM> includes two stages with one impeller <NUM> positioned on one side of the motor <NUM> and one impeller <NUM> positioned on the other side of the motor <NUM>. Also, the blower <NUM> has axial symmetry with both the inlet <NUM> and outlet <NUM> aligned with an axis <NUM> of the blower <NUM>. In contrast, the blower <NUM> provides an alternative arrangement of the stationary portion.

A stationary portion of the blower <NUM> includes a housing <NUM> with first and second housing parts <NUM>, <NUM>, a stator component <NUM> including stator vanes <NUM>, and first and second shields <NUM>, <NUM>. A rotating portion of the blower <NUM> includes a rotatable shaft or rotor <NUM> adapted to be driven by motor <NUM> and first and second impellers <NUM>, <NUM> provided to end portions of the shaft <NUM>. The motor <NUM> includes a magnet <NUM> provided to shaft <NUM> and a stator assembly <NUM> to cause spinning movement of the shaft <NUM> via the magnet <NUM>.

In an embodiment, as shown in <FIG>, the blower <NUM> may be relatively compact and have an overall diameter D of about <NUM>-<NUM>, e.g., <NUM>, and an overall length L of about <NUM>-<NUM>, e.g., <NUM>. Each impeller <NUM>, <NUM> may have a diameter of about <NUM>-<NUM>, e.g., <NUM>. However, other suitable sizes are possible.

As shown in <FIG>, the stator component <NUM> includes a base <NUM>, an annular flange <NUM> extending from the base <NUM> to support the stator component <NUM> within the housing <NUM>, a tube <NUM> to retain and align the bearings <NUM>, <NUM> that rotatably support the shaft <NUM>, and a plurality of stator vanes <NUM>. Similar to the above embodiments, the stator component <NUM> may be integrally formed (e.g., injection molded) as a one-piece structure.

In the illustrated embodiment, each vane <NUM> includes an outer portion <NUM> that is sufficiently long so that it can support and maintain the stator assembly <NUM> in an operative position. As illustrated, the outer portion <NUM> of each vane <NUM> provides an interior surface <NUM> that engages an exterior surface <NUM> of the stator assembly <NUM>. In an embodiment, opposing vanes may define a diameter d of about <NUM>-<NUM>, e.g., <NUM>, for securing the stator assembly <NUM> in position. However, other suitable sizes are possible, e.g., depending on the size of the stator assembly.

In addition, the free end of the outer portion <NUM> of each vane <NUM> is adapted to engage the shield <NUM> so that it can support and maintain the shield <NUM> in an operative position.

The first or upper shield <NUM> includes an inner annular flange <NUM> and an outer annular flange <NUM>. The inner annular flange <NUM> is structured to engage the upper end of the tube <NUM> of the stator component <NUM>, e.g., with a friction fit, and the outer annular flange <NUM> is structured to engage the outer portion <NUM> of the vanes <NUM>, e.g., with a friction fit.

The second or lower shield <NUM> is supported and maintained by the second housing part <NUM> in an operative position. The hub <NUM> at the central portion of the shield <NUM> is shaped to direct the air flow down towards the outlet <NUM>.

In the illustrated embodiment, the second housing part <NUM> of the housing <NUM> includes a plurality of stator vanes <NUM>, e.g., between <NUM> and <NUM> (e.g., about <NUM>-<NUM> )stator vanes, to direct airflow towards the outlet <NUM>. As illustrated, the stator vanes <NUM> support the shield <NUM> within the second housing part <NUM> adjacent the outlet <NUM>. Also, at least one of the stator vanes <NUM> includes a projection <NUM> adapted to extend through an opening <NUM> provided in the shield <NUM> to align and secure the shield <NUM> in position.

Each of the blowers <NUM>, <NUM>, <NUM> described above are supported within an outer casing or chassis (e.g., forming a portion of a NIVV device such as a PAP device or flow generator). According to the invention, each blower is supported within the outer casing by a support system that is structured to provide support and provide a seal between the inlet and the outlet sides of the blower.

According to the invention, which is only visible in <FIG>, the outer casing <NUM> includes a base <NUM> and a cover <NUM> provided to the base <NUM>. The support system <NUM> includes a side <NUM> support and a bottom support <NUM> to support the blower (e.g., blower <NUM>).

As illustrated, the side support <NUM> is in the form of an annular ring (e.g., made of Silicone or TPE) that is provided to the blower housing (e.g., housing <NUM>) and includes an end portion <NUM> adapted to engage within a respective slot <NUM> defined between the base <NUM> and cover <NUM>. The bottom support <NUM> is in the form of multiple flexible feet or flexible pegs, e.g., <NUM> feet, that are adapted to engage the base wall of base <NUM>. The annular ring <NUM> (also referred to as a divider seal or a soft girdle/seal) suspends/supports the blower <NUM> in the chassis and divides or seals the inlet side of the blower from the outlet side of the blower (i.e., divide or separate low and high pressure sides), e.g., to avoid the need for a connection tube that directs flow towards the outlet of the outer casing <NUM>. The feet <NUM> may act as a backup seal between the inlet and outlet sides of the blower or a backup support for the blower, e.g., in case the ring <NUM> creeps in old age.

As illustrated, a relatively small outlet muffler volume V1 is provided on the outlet side of the blower and a relatively small inlet muffler volume is provided on the inlet side of the blower V2.

In an embodiment, the annular ring <NUM> and feet <NUM> may be overmolded onto the outside of the first housing part <NUM> of the blower <NUM> (i.e., the first stage cover of the blower). As illustrated, an overmolded feeder <NUM> may interconnect the overmolded ring <NUM> with each of the overmolded feet <NUM>. For example, the first housing part <NUM> (along with the second housing part <NUM>) may be constructed of a relatively rigid plastic material, e. g, polycarbonate (PC) or acrylonitrile butadiene styrene (ABS), and the overmolded ring <NUM>, feet <NUM>, and feeders <NUM> may be constructed of an elastomeric material, e.g., Versollan™. Alternative, the ring, feet, and/or feeders may be separate molded pieces that are attached in an operative position.

The support system <NUM> provides an arrangement that avoids the need for inlet and outlet seals adjacent the inlet and outlet of the blower. In addition, the support system <NUM> is constructed of an elastomeric material that isolates (e.g., vibration isolated) and/or serves as a suspension between the blower <NUM> and the outer casing <NUM>, e.g., without using springs. In an embodiment, additional supports (e.g., feet or pegs) may be provided to the top and/or sides of the blower so that the outer casing and the blower supported therein may be oriented in any direction, e.g., casing may be positioned on its side rather than vertically.

Each of the blowers <NUM>, <NUM>, <NUM> described above may include a sealing arrangement between the housing parts of the housing, e.g., to prevent leak or loss of pressure.

In an embodiment, as shown in <FIG>, the end portion of the first housing part <NUM> of the blower (i.e., the first stage cover of the blower) includes a stepped configuration with first and second steps <NUM>(<NUM>), <NUM>(<NUM>). Each of the steps <NUM>(<NUM>), <NUM>(<NUM>) is provided with a sealing structure, i.e., first and second seals <NUM>(<NUM>), <NUM>(<NUM>) respectively. In an embodiment, the seals <NUM>(<NUM>), <NUM>(<NUM>) may be overmolded with the first housing part <NUM> in a manner as described above, e.g., elastomeric seals <NUM>(<NUM>), <NUM>(<NUM>) overmolded to relatively rigid plastic first housing part <NUM>.

The end portion of the second housing part <NUM> of the blower includes a similar stepped configuration as the first housing part <NUM>, e.g., first and second steps <NUM>(<NUM>), <NUM>(<NUM>).

As illustrated, when the first and second housing parts <NUM>, <NUM> are coupled to one another, the first seal <NUM>(<NUM>) of the first housing part <NUM> engages the first step <NUM>(<NUM>) of the second housing part <NUM> to provide a seal between housing parts <NUM>, <NUM>. Also, the second step <NUM>(<NUM>) of the first housing part <NUM> and the second step <NUM>(<NUM>) of the second housing part <NUM> cooperate to define a slot adapted to receive and support the edge <NUM> of stator component <NUM> including stator vanes <NUM> (e.g., similar to stator component <NUM>). The second seal <NUM>(<NUM>) provides a seal between the stator component <NUM> and the housing parts <NUM>, <NUM>.

In addition, multiple snap-fit members <NUM>, e.g., <NUM> snap-fit members, are provided to the end portion of the first housing part <NUM> that are adapted to engage a respective shoulder <NUM> provided to the second housing part <NUM> with a snap-fit. The snap-fit members <NUM> secure the first and second housing parts <NUM>, <NUM> to one another and maintain the seal. However, it should be appreciated that the first and second housing parts may be secured to one another in other suitable manners, e.g., welding, adhesive (e.g., gluing), heat staking, fasteners (e.g., screws), etc..

<FIG> also illustrates an overmolded ring <NUM> and feeder <NUM> provided to the first housing part <NUM>, and the ring <NUM> engaged within the slot between the base <NUM> and cover <NUM> of an outer casing as described above. In addition, <FIG> illustrates impeller <NUM> between stator component <NUM> and the outlet of the blower.

In an alternative embodiment, as shown in <FIG>, the edge <NUM> of the stator component <NUM> may include a relatively rigid protrusion <NUM> (e.g., v-shaped protrusion) adapted to engage the second seal <NUM>(<NUM>), e.g., to improve grip and sealing. Also, the second seal <NUM>(<NUM>) may have a more block-like configuration, rather than a bead-like configuration as shown in <FIG>.

<FIG> to <FIG> illustrate a another blower <NUM> which can be used in the present invention. Similar to the blowers <NUM>, <NUM>, <NUM> described above, the blower <NUM> includes two stages with one impeller <NUM> positioned on one side of the motor <NUM> and one impeller <NUM> positioned on the other side of the motor <NUM>. Also, the blower <NUM> has axial symmetry with both the inlet <NUM> and outlet <NUM> aligned with an axis <NUM> of the blower <NUM>.

A stationary portion of the blower <NUM> includes a housing <NUM> with first and second housing parts <NUM>, <NUM>, a stator component <NUM>, and first and second shields <NUM>, <NUM>. A rotating portion of the blower <NUM> includes a rotatable shaft or rotor <NUM> adapted to be driven by motor <NUM> and first and second impellers <NUM>, <NUM> (e.g., mixed flow) provided to end portions of the shaft <NUM>. The motor <NUM> includes a magnet <NUM> provided to shaft <NUM> and a stator assembly <NUM> to cause spinning movement of the shaft <NUM> via the magnet <NUM>.

The stator assembly <NUM> includes windings <NUM> and a stator or stator lamination stack <NUM> (e.g., slotless or toothless) provided to the windings <NUM>. In an embodiment, the resistance of the windings <NUM> and/or current draw (e.g., at start-up) may be monitored to determine temperature, which may be used to indicate faults in the motor (e.g., bearing fault detection, bearing end of life failure or rubbing condition, software fault in the electronic drive systems). For example, after the motor has stopped but still remains warm, the resistance of the windings may be measured (e.g., via a circuit in the blower). It is noted that resistance of the windings changes with temperature in a known way. If the resistance was such that it implied a much hotter than usual temperature, the device would go into a fault mode, e.g., and prompt the user to have the blower serviced. Several blower faults tend to lead to unusually high temperatures, e.g., bearing end of life failures or software faults in electronic drive systems.

The inlet <NUM> is provided by the first housing part <NUM> (also referred to as a first stage cover) at one end and the outlet <NUM> is provided by the second housing part <NUM> (also referred to as a final stage cover) at the other end.

As best shown in <FIG> to <FIG>, the stator component <NUM> includes an annular base portion <NUM>, a shield portion <NUM>, a tube or bearing tube <NUM> extending from the shield portion <NUM>, and a plurality of spaced apart side walls <NUM> extending between the base portion <NUM> and the shield portion <NUM>. As illustrated, the stator component <NUM> forms a cylindrical "cage" and the spaced apart side walls <NUM> define openings <NUM> into the "cage". The stator component <NUM> may be integrally formed (e.g., injection molded) as a one-piece structure. However, the stator component <NUM> may be constructed in other suitable manners and/or may be made in separate parts.

As best shown in <FIG> to <FIG>, the base portion <NUM> is sandwiched between the first and second housing parts <NUM>, <NUM> to support the stator component <NUM> within the housing <NUM>. In addition, the second housing part <NUM> may include a protrusion <NUM> (e.g., v-shaped protrusion as best shown in <FIG>) adapted to engage the first housing part <NUM>, e.g., to improve grip and sealing.

In an alternative embodiment, as shown in <FIG>, the first housing part <NUM> may include a connecting portion <NUM>(<NUM>) structured to overlap and/or overhang a connecting portion <NUM>(<NUM>) of the second housing part <NUM>. Similar to the above embodiment, the base portion <NUM> of the stator component <NUM> is sandwiched between the first and second housing parts <NUM>, <NUM>. In addition, the second housing part <NUM> may include a protrusion <NUM> for sealing against the first housing part <NUM>.

The outer edge of the shield portion <NUM> substantially aligns with or extends radially beyond the outer edge of the impeller <NUM>. The shield portion <NUM> provides a narrow annular gap <NUM> between its outer edge and the side wall of the housing part <NUM>, which is sufficient to direct gas into the stator component <NUM>. The shield portion <NUM> includes an opening <NUM> that allows access to the interior of the tube <NUM>.

Similar to the above embodiments, the tube <NUM> is structured to retain and align bearings <NUM>, <NUM> (e.g., of mixed bearing sizes) that rotatably support the shaft <NUM>. In addition, the tube <NUM> is sufficiently "magnetically transparent", which allows the stator assembly <NUM> to act on the magnet <NUM> positioned within the tube <NUM> without significant loss of flux density and/or increased heat, if any.

Also, the tube <NUM> may be constructed of an acoustically damped material to damp vibrations caused by rotor operation, e.g., polypropylene, nylon (reinforced), liquid crystal polymer (LCP) with ceramic loading (conduct heat), polyphenylene sulfide (PPS) with graphite fill, polyetheretherketone (PEEK). If ball bearings are utilized, the number of balls within the bearings may be optimized to minimize vibrations.

A cap portion <NUM> is provided to the shield portion <NUM> along the opening <NUM>. The cap portion <NUM> provides a stop for the bearing <NUM> and hence retains the shaft <NUM> within the tube <NUM>. In addition, the cap portion <NUM> may act as a spacer for the impeller <NUM>.

Washers <NUM> and a spring or biasing element <NUM> may be provided between the bearing <NUM> and the rotor magnet <NUM> and a spacer <NUM> may be provided between the bearing <NUM> and the rotor magnet <NUM>, e.g., to maintain alignment/spacing of the rotor magnet <NUM> with the stator assembly <NUM>, act as wear stop, and/or provide a pre-load. Also, the spacer <NUM> (e.g., constructed of metallic ferrite) adjacent the bearing <NUM> acts as a magnetic shunt or flux shield to direct magnetic field towards the windings <NUM> and away from the bearing <NUM>, e.g., to avoid heating bearing. It should be appreciated that such a spacer or shield may also be provided adjacent the bearing <NUM>. The flux shield may be an optional component, but may increase bearing/lube life due to reduced eddy current losses in the bearing outer races and balls.

As shown in <FIG>, the spring <NUM> provides an inner race pre-load (IRP), e.g., about <NUM> lb spring load, on the bearing <NUM>. Specifically, the bearing <NUM> includes an inner race <NUM>(<NUM>), an outer race <NUM>(<NUM>), and ball bearings <NUM>(<NUM>) provided between the inner and outer races (e.g., there may be a clearance between the ball bearings and the races). The inner and outer races <NUM>(<NUM>), <NUM>(<NUM>) provide surfaces upon which the ball bearings <NUM>(<NUM>) run. Also, the bearing may include a spacer element between the inner and outer races to maintain spacing between the ball bearings (e.g., cylinder with openings to receive respective ball bearings). In the illustrated embodiment, the spring <NUM> is constructed and arranged to engage the inner race <NUM>(<NUM>) of the bearing <NUM> to provide a spring load to the bearing, which brings the ball bearings into contact with the races (i.e., load transmitted from the inner race to the ball bearings, and from the ball bearings to the outer race).

In an alternative embodiment, the spring may be constructed and arranged to provide an outer race pre-load (ORP) on the bearing, e.g., see <FIG> and <FIG> to <FIG> described below.

Similar to the embodiment described above, the shield portion <NUM> and cap portion <NUM> cooperate to provide by-pass passages or conduits <NUM> (as shown in <FIG> and <NUM>-<NUM>) to provide pressure balance across the bearings <NUM>, <NUM>. Specifically, the by-pass passages <NUM> provide a short circuit of pressure around the tube <NUM> and hence the bearings <NUM>, <NUM>.

In an embodiment, a tight tolerance (i.e., a small gap) is provided between the inner diameter of the cap portion <NUM> and the shaft <NUM> which increases the impedance between the cap portion <NUM> and the shaft <NUM>. Hence, air can flow with less resistance through the by-pass passage or bleed hole <NUM> (e.g., tight tolerance may also apply to the by-pass arrangement shown in <FIG>).

Without a by-pass, air may flow through the bearings, upwards from the high pressure side to the low pressure side. The by-pass passage connects the high pressure zone to a point above the top bearing. This means high pressure exists more or less equally across the pair of bearings. Therefore, there is little flow through the bearings, and the grease neither dries out nor gets displaced, thereby improving bearing longevity.

The stator assembly <NUM> is provided along the exterior surface of the tube <NUM>. In addition, the stator component <NUM> and first shield <NUM> cooperate to support and maintain the stator assembly <NUM> in an operative position, as described in greater detail below.

As best shown in <FIG> to <FIG>, the first shield <NUM> includes a base <NUM> and a plurality of stator vanes <NUM> provided to the base <NUM>. The first shield <NUM> is attached to the stator component <NUM>, e.g., by engaging pins <NUM> on the first shield <NUM> with respective openings <NUM> provided in the base portion <NUM> of the stator component <NUM> (e.g., pins heat staked into position). However, the first shield <NUM> may be attached to the stator component <NUM> in other suitable manners.

The plurality of stator vanes <NUM>, e.g., between <NUM> and <NUM><NUM> stator vanes, are structured to direct airflow towards an orifice <NUM> in the base <NUM>. In the illustrated embodiment, the stator component <NUM> has six stator vanes <NUM>. Each vane <NUM> is substantially identical and has a generally spiral shape. In addition, each vane <NUM> includes an inner portion <NUM> (adjacent the orifice <NUM>) and an outer portion <NUM>. As best shown in <FIG>, the inner portion <NUM> is recessed (e.g., reduced in height) with respect to the outer portion <NUM>.

As best shown in <FIG> and <FIG>, the windings <NUM> of the stator assembly <NUM> are engaged or supported by the recessed, inner portion <NUM> of the stator vanes <NUM>, and the stack <NUM> of the stator assembly <NUM> is engaged or supported by the outer portion <NUM> of the stator vanes <NUM>.

In addition, the exterior surface <NUM> of the stack <NUM> (e.g., see <FIG> and <FIG>) includes a toothed configuration that is adapted to engage or interlock with spaced-apart teeth <NUM> provided by interior surfaces of the spaced apart side walls <NUM> (e.g., see <FIG>). Remaining portions of the toothed configuration of the stack <NUM> at least partially protrude through the openings <NUM> in the stator component <NUM>, e.g., flush with exterior surfaces of the side walls <NUM> (see <FIG> and <FIG>). Thus, the stator component <NUM> and first shield <NUM> cooperate to retain or secure the stator assembly <NUM> in an operative position.

As shown in <FIG> to <FIG> and <FIG>, wires <NUM> (e.g., three wires for a three phase motor) extend from the windings <NUM> to outside the housing <NUM> to conduct current from an external source to the windings <NUM>. As illustrated, slots <NUM> are provided through the stator component <NUM> (see <FIG>) and slots <NUM> are provided through the housing <NUM> (see <FIG>) to accommodate passage of respective wires <NUM> from the windings <NUM> to outside the housing <NUM>.

In the illustrated embodiment, the stack <NUM> and windings <NUM> are exposed to the flow of gas, e.g., via the openings <NUM> in the stator component <NUM>, as shown in <FIG>, <FIG>, and <FIG>. This arrangement allows forced-convection cooling of the stack <NUM>/windings <NUM> as gas flows through the stator component <NUM> in use. In addition, this arrangement may assist in heating the patient air.

As shown in <FIG>, the second shield <NUM> includes a plurality of stator vanes <NUM>, e.g., between <NUM> and <NUM> stator vanes, to direct airflow towards the outlet <NUM>. In the illustrated embodiment, the shield <NUM> has <NUM> stator vanes. Each vane <NUM> is substantially identical and has a generally spiral shape. In addition, each vane <NUM> includes an inner portion <NUM> (adjacent the hub <NUM>) and an outer portion <NUM>. As best shown in <FIG> and <FIG>, the outer portion <NUM> is recessed (e.g., reduced in height) with respect to the inner portion <NUM>, and a contoured edge <NUM> extends between the inner and outer portions <NUM>, <NUM>.

In the illustrated embodiment, the stator vanes <NUM> support the shield <NUM> within the second housing part <NUM> adjacent the outlet <NUM>. As illustrated, the contoured edge <NUM> of the shield <NUM> engages the edge of the outlet <NUM> to align the shield <NUM> with the outlet <NUM> (see <FIG>). The hub <NUM> and inner portion <NUM> of the vanes <NUM> extend at least partially through the outlet <NUM> and the outer portion <NUM> of the vanes <NUM> engage the lower wall of the second housing part <NUM>, as best shown in <FIG>. The hub <NUM> at the central portion of the shield <NUM> is shaped to direct the air flow down towards the outlet <NUM>.

In addition, the second shield <NUM> includes pins <NUM> that are adapted to engage with respective openings <NUM> provided in lower wall of the second housing part <NUM>, e.g., pins heat staked into position, as shown in <FIG>. However, the second shield <NUM> may be attached to the second housing part <NUM> in other suitable manners.

The second shield <NUM> (also referred to as a final stage disc) includes a disc or shield to cover the stator vanes <NUM> in order to keep any discontinuities away from the blades of the impeller <NUM>. However, other structure may be provided to keep any discontinuities away from the impeller blades. For example, the stator vanes <NUM> may be integrated into the second housing part <NUM>, and the impeller <NUM> may include a lower shroud to act as a rotating shroud or shield between the impeller blades and stator vanes <NUM>.

In the first stage, air enters the blower <NUM> at the inlet <NUM> and passes into the first impeller <NUM> where it is accelerated tangentially and directed radially outward. It is noted that suction is developed at the inlet to draw air into the blower. Air then flows in a spiral manner with a large tangential velocity component and also an axial component passing through the gap <NUM> defined by the outer edge of the shield portion <NUM> and the side wall of housing part <NUM>. Air then enters the stator component <NUM> via the openings <NUM> in the stator component <NUM>, and flows into the stator vanes <NUM> of the first shield <NUM> where it is directed radially inwardly towards orifice <NUM>, and thereafter onto the second stage.

In the second stage, air passes into the second impeller <NUM> where it is accelerated tangentially and directed radially outward. Air then flows in a spiral manner with a large tangential velocity component and also an axial component passing through the gap <NUM> defined by the outer edge of the second shield <NUM> and the side wall of housing part <NUM>. Air then enters the stator vanes <NUM> formed in the shield <NUM> and is directed towards the outlet <NUM>.

In the above-described embodiments, the blowers include stator vanes to direct airflow towards a second stage and towards the outlet. Such stator vanes help to straighten the flow and remove the "swirl" caused by the impellers. In alternative embodiments, the stator vanes may be replaced with alternative structure to direct or straighten flow. For example, a grid, mesh (e.g., woven), honeycomb-like structure, and/or extrusion (e.g., helical) may be provided to direct flow in use.

Also, in an alternative embodiment, multiple tangential feeds may be provided to the axial outlet <NUM> to direct flow tangentially from the outlet.

In an embodiment, the tube of the stator component may be used as a mandrel to help form the windings of the stator assembly. The tube may be structured and shaped to facilitate its use as a mandrel. For example, the cylindrical and tapered construction of the tube may facilitate its use as a mandrel. The shape may be polygonal, e.g., rectangle, triangle, square, pentagon, hexagon, etc. In addition, the tube may include one or more structural components, such as splines, to aid with separation of the windings from the mandrel.

<FIG> illustrates another blower which can be used in the present invention. The blower is similar to blower <NUM> described above and indicated with similar reference numerals. In contrast, the first shield <NUM> (i.e., the interstage "de-swirl" vane) includes a lip region or flange <NUM>(<NUM>) adapted to engage or seal against the second housing part <NUM>. Specifically, the lip region <NUM>(<NUM>) of the first shield <NUM> is structured to engage the base portion <NUM> of the stator component <NUM>, and the lip region <NUM>(<NUM>) and base portion <NUM> are supported and/or sandwiched between the first and second housing parts <NUM>, <NUM> to support the first shield <NUM> and the stator component <NUM> within the housing <NUM>. Moreover, the lip region/base portion arrangement is structured to provide an interstage seal to prevent air leakage from the second stage back into the first stage in use. In addition, the connecting portion <NUM>(<NUM>)of the first housing part <NUM> is structured to overlap and/or overhang the connecting portion <NUM>(<NUM>) of the second housing part <NUM>.

However, an interstage seal may be provided in other suitable manners. For example, a gasket or gooey sealant may be used at the interfaces of the shield <NUM>, stator component <NUM>, and housing parts <NUM>, <NUM>. In another embodiment, one or more of the interface surfaces may be overmolded with a soft silicone or TPE.

<FIG> to <FIG> illustrate another blower <NUM> which can be used in the present invention. Similar to the blowers described above, the blower <NUM> includes two stages with one impeller <NUM> positioned on one side of the motor <NUM> and one impeller <NUM> positioned on the other side of the motor <NUM>. Also, the blower <NUM> has axial symmetry with both the inlet <NUM> and outlet <NUM> aligned with an axis <NUM> of the blower <NUM>.

In contrast to the blowers described above, the bearings <NUM>, <NUM> that support shaft <NUM> are retained by a metal housing assembly (rather than a plastic tube), as described in greater detail below. It is noted that the metal housing assembly includes a "cage"-like adaptor that supports the metal housing assembly within the blower housing and allows gas to flow into the first shield and onto the second stage in a similar manner to the "cage" like stator component described above.

A stationary portion of the blower <NUM> includes a housing <NUM> with first and second housing parts <NUM>, <NUM>, a metal housing assembly <NUM>, and first and second shields <NUM>, <NUM>. A rotating portion of the blower <NUM> includes a rotatable shaft or rotor <NUM> adapted to be driven by motor <NUM> and first and second impellers <NUM>, <NUM> provided to end portions of the shaft <NUM>. The motor <NUM> includes a magnet <NUM> provided to shaft <NUM> and a stator assembly <NUM> to cause spinning movement of the shaft <NUM> via the magnet <NUM>.

The housing assembly <NUM> is constructed of a metallic material and includes a main housing <NUM>, an end bell <NUM>, and an adaptor <NUM> (e.g., secured to one another by one or more fasteners <NUM>). As illustrated, the main housing <NUM> provides a recess for supporting bearing <NUM> and the end bell <NUM> provides a recess for supporting bearing <NUM>. The main housing and end bell are structured to support bearings of the same size. However, the main housing and end bell may be structured to support mixed bearing sizes.

The metal bearing support provided by the housing assembly <NUM> improves heat transfer from the bearings in use. Also, the main housing <NUM>, end bell <NUM>, and adaptor <NUM> (e.g., constructed of aluminum) may be machined bar stock. In an embodiment, the end bell and adaptor may be aluminum die cast pieces for high volume production.

As best shown in <FIG>, the adaptor <NUM> forms a cylindrical "cage" that defines openings <NUM> into the cage.

The main housing <NUM> and end bell <NUM> cooperate to support and maintain the stator assembly <NUM> in an operative position.

Similar to the <FIG> embodiment described above, a lip region <NUM>(<NUM>) of the first shield <NUM> is structured to engage the base <NUM>(<NUM>) of the adaptor <NUM>, and the lip region <NUM>(<NUM>) and base <NUM>(<NUM>) are supported and/or sandwiched between the first and second housing parts <NUM>, <NUM> to support the first shield <NUM> and housing assembly <NUM> within the housing <NUM>. In addition, the lip region/base arrangement is structured to provide an interstage seal to prevent air leakage from the second stage back into the first stage in use.

In the illustrated embodiment, a spacer or flux shield <NUM> is provided between each bearing <NUM>, <NUM> and the rotor magnet <NUM>. In addition, a spring or biasing element <NUM> is provided between the bearing <NUM> and the end cap <NUM>.

The spring <NUM> (e.g., crest-to-crest spring) provides an outer race preload (ORP) (outer race preload also shown in <FIG>) on the bearing <NUM> (instead of an inner race preload such as that shown in <FIG>). Specifically, the spring <NUM> is constructed and arranged to engage the outer race <NUM>(<NUM>) of the bearing <NUM> to provide a spring load to the bearing, which brings the ball bearings into contact with the races (i.e., load transmitted from the outer race <NUM>(<NUM>) to the ball bearings <NUM>(<NUM>), and from the ball bearings <NUM>(<NUM>) to the inner race <NUM>(<NUM>)).

In an embodiment, the ORP arrangement may reduce or eliminate corrosion of the second stage bearing <NUM> (e.g., at the inner race) over the life of the blower.

In the first stage, air enters the blower <NUM> at the inlet <NUM> and passes into the first impeller <NUM> where it is accelerated tangentially and directed radially outward. It is noted that suction is developed at the inlet to draw air into the blower. Air then flows in a spiral manner with a large tangential velocity component and also an axial component passing through the gap <NUM> defined by the outer edge of the housing assembly <NUM> and the side wall of housing part <NUM>. Air then flows into the stator vanes <NUM> of the first shield <NUM> via the openings <NUM> in the adaptor <NUM> where it is directed radially inwardly onto the second stage.

<FIG> to <FIG> illustrate a stator <NUM> for a stator assembly which can be used in the present invention. The stator <NUM> includes an outer portion <NUM>(<NUM>) (<FIG>) and an inner portion <NUM>(<NUM>) (<FIG>) structured to be received within the outer portion <NUM>(<NUM>). <FIG> shows the stator <NUM> with the assembled outer and inner portions <NUM>(<NUM>), <NUM>(<NUM>).

The inner portion <NUM>(<NUM>) has a plurality of stator teeth <NUM>, e.g., six stator teeth, on which stator coils or windings are wound. The outer portion <NUM>(<NUM>) is ring shaped and includes a plurality of recesses <NUM> along its inner circumference adapted to receive respective teeth of the inner portion <NUM>(<NUM>). When assembled, the stator <NUM> provides a closed slot arrangement.

The outer circumference of the outer portion <NUM>(<NUM>) includes a toothed configuration that is adapted to engage or interlock with the stator component (e.g. for use in blower <NUM> similar to the arrangement described above in relation to <FIG> and <FIG>). In addition, one or more slots <NUM> may be provided in the outer circumference of the outer portion <NUM>(<NUM>) to accommodate passage of respective wires from the windings.

This "closed-slot" stator-core arrangement facilitates the insertion of magnet wire because magnet wire can be inserted from the outside via a generously wide slot opening. That opening becomes closed when the outer portion <NUM>(<NUM>) is provided to the toothed inner portion <NUM>(<NUM>). In its final assembled form, there is no opening of the slot, and as such, there is little magnetic detent (or magnetic cogging effect) produced by the interaction of the rotor's salient poles and the stator. It is a cost-effective, low cogging configuration.

In the illustrated embodiment, each tooth <NUM> of the inner portion <NUM>(<NUM>) has a generally T-shaped arrangement with substantially square edges. In an alternative embodiment, as shown in <FIG>, the end portion of each tooth <NUM> (and corresponding recesses <NUM> in the outer portion <NUM>(<NUM>)) may be more rounded.

In yet another embodiment, the stator assembly may include an ironless and slotless stator (i.e., using air as the flux return path, rather than using iron to concentrate the flux).

<FIG> to <FIG> illustrate another blower <NUM> which can be used in the present invention. Similar to the blowers described above, the blower <NUM> includes two stages with one impeller <NUM> positioned on one side of the motor <NUM> and one impeller <NUM> positioned on the other side of the motor <NUM>. Also, the blower <NUM> has axial symmetry with both the inlet <NUM> and outlet <NUM> aligned with an axis of the blower <NUM>.

In this embodiment, the stator <NUM> of the stator assembly includes a slotted configuration. As best shown in <FIG>, the stator or lamination stack <NUM> includes a ringshaped main body <NUM>(<NUM>) and a plurality of stator teeth <NUM>(<NUM>), e.g., six stator teeth, extending radially inwardly from the main body <NUM>(<NUM>). The stator coils or windings <NUM> are wound on respective teeth <NUM>(<NUM>) as shown in <FIG>. The windings can be inserted from the inside via respective slot openings (spacing between teeth).

Similar to arrangements described above, the outer circumference of the main body <NUM>(<NUM>) includes a toothed configuration that is adapted to engage or interlock with the stator component <NUM>. In addition, one or more slots <NUM> may be provided in the outer circumference of the main body <NUM>(<NUM>) to accommodate passage of respective wires from the windings <NUM>.

The remaining portions of the blower are similar to arrangements described above, e.g., housing <NUM> with first and second housing parts <NUM>, <NUM>, "cage"-like stator component <NUM> with bearing tube <NUM>, and first and second shields <NUM>, <NUM>.

In this embodiment, the blower <NUM> includes a coreless motor in which the windings or magnet wire are wound directly on the stator component thereby eliminating a stator or lamination stack. For example, as best shown in <FIG>, windings or magnet wire <NUM> may be wound directly on the bearing tube <NUM> of the stator component <NUM>. In an embodiment, the windings may be at least partially supported by side walls of the stator component.

The remaining portions of the blower are similar to arrangements described above, e.g., housing <NUM> with first and second housing parts <NUM>, <NUM>, "cage"-like stator component <NUM>, and first and second shields <NUM>, <NUM>. In the illustrated embodiment, the first housing part <NUM> may include one or more guide structures <NUM> for guiding magnet wire outside the housing, e.g., binding post for looping wire.

In an embodiment, the bearings supporting the shaft may be bonded to respective ends of the bearing tube by a plasma treatment stage. For example, with respect to the embodiment of blower <NUM>, plasma may be used to treat the plastic surface of the first stage bearing seat of bearing tube <NUM> that engages the outer race of bearing <NUM>. The plasma treatment allows the adhesive of choice (e.g., a Loctite cyanoacrylate compound) to wet nicely when applied. This wetting action has been shown to increase the bondline strength and also reduce the variation in that process (as determined by shear strength). The bondline holds the rotor assembly within the tube and stator assembly.

In an alternative embodiment, liquid primers may be used to treat the bearing seat before the adhesive (e.g., a Loctite cyanoacrylate compound) is applied. Also, an alternative to cyanoacrylate compound as an adhesive with the plasma/primers may be epoxy.

In an embodiment, the first and second housing parts of the housing may be bonded together with ultrasonic welding using a shear joint.

Also, in an embodiment, combinations of rigid and softer materials may be molded in a two-shot process (e.g., co-molding) to improve sealing in various positions through the blower.

In order to have the lead wires being the same length as they exit the blower housing, a "binding post" or "cleat" may be positioned on the outside of the housing. One or more wires may be looped around that binding post so that the lengths of the wires can be equalized.

In an embodiment, a labyrinth seal may be provided to allow the pressure to equalize between the outboard side of the first-stage bearing and the outboard side of the second-stage bearing to the extent that it is possible with minimal recirculating flow beneath the first-stage impeller (e.g., see <FIG> and <FIG>).

Claim 1:
A positive airway pressure device for generating a supply of pressurized gas to be provided to a patient for treatment, the positive airway pressure device comprising:
an outer casing (<NUM>);
a blower (<NUM>) including a housing (<NUM>) having an inlet (<NUM>) along an inlet side thereof and an outlet (<NUM>) along an outlet side thereof, the inlet (<NUM>) and the outlet (<NUM>) being co-axially aligned,
wherein the blower (<NUM>) is configured to draw a supply of gas into the housing (<NUM>) through the inlet (<NUM>) and provide a pressurized flow of gas at the outlet (<NUM>); and
a support system (<NUM>) provided between the blower (<NUM>) and the outer casing (<NUM>),
wherein the support system (<NUM>) includes an annular seal (<NUM>) provided to an outer surface of the housing (<NUM>) and adapted to engage the outer casing (<NUM>) to support the blower (<NUM>) within the outer casing (<NUM>) and separate the inlet side of the blower (<NUM>) from the outlet side of the blower (<NUM>),
characterised in that the support system (<NUM>) further comprises multiple feet (<NUM>) provided to a bottom of the blower (<NUM>) and adapted to engage a base of the outer casing (<NUM>) and the support system (<NUM>) is constructed of an elastomeric material without using springs.