Patent Description:
The present technology relates to an impeller for a blower for a respiratory therapy device, such as a positive airway pressure (PAP) device or a ventilator. In an example, the blower may be used in a PAP device used for the delivery of respiratory therapy to a patient. More specifically, the impeller may be particularly suited for a small respiratory pressure therapy device, such as one designed to minimise a footprint, to be portable, or to be wearable.

Various therapies, such as Continuous Positive Airway Pressure (CPAP) therapy, Non-invasive ventilation (NIV) and Invasive ventilation (IV) have been used to treat one or more respiratory disorders.

These therapies may be provided by a treatment system or device. Such systems and devices may also be used to diagnose a condition without treating it.

A treatment system may comprise a Respiratory Pressure Therapy Device (RPT device), an air circuit, a humidifier, a patient interface, and data management.

A patient interface may be used to interface respiratory equipment to its wearer, for example by providing a flow of air to an entrance to the airways. The flow of air may be provided via a mask to the nose and/or mouth, a tube to the mouth or a tracheostomy tube to the trachea of a patient.

A respiratory pressure therapy (RPT) device may be used to deliver one or more of a number of therapies described above, such as by generating a flow of air for delivery to an entrance to the airways. The flow of air may be pressurised. Examples of RPT devices include a CPAP device and a ventilator.

Air pressure generators are known in a range of applications, e.g. industrial-scale ventilation systems. However, air pressure generators for medical applications have particular requirements not fulfilled by more generalised air pressure generators, such as the reliability, size and weight requirements of medical devices. In addition, even devices designed for medical treatment may suffer from shortcomings, pertaining to one or more of: comfort, noise, ease of use, efficacy, size, weight, manufacturability, cost, and reliability.

An example of the special requirements of certain RPT devices is acoustic noise.

Table of noise output levels of prior RPT devices (one specimen only, measured using test method specified in ISO <NUM> in CPAP mode at <NUM> cmH<NUM>O).

One suitable form of pressure generators for RPT devices may be a centrifugal air blower, which may comprise one or more impellers. A designer for an impeller may face challenges, as a designer of a device may be presented with an infinite number of choices to make.

For example, an impeller for an RPT device may have competing desirable properties such as high efficiency, flow rate and pressure output requirements for therapy, small size and rotational inertia, low cost, high mechanical strength and durability. In meeting one, for instance, by simply reducing a diameter of an existing impeller, its maximum available flow rate may be decreased, while its size and inertia are advantageously decreased. Some aerodynamic features for example may improve an efficiency of the impeller, however may increase its costs as the required manufacturing process becomes more complicated.

Simply put, design criteria often conflict, meaning that certain design choices are far from routine or inevitable.

<CIT> relates to a single ended or double-ended blower comprising a blower motor assembly supporting opposed firs and second shaft ends, the first and second shaft ends having respective first and second impellers attached thereto and enclosed within first and second volutes, respectively, wherein the first volute is connected to an inlet and the second volute is connected to an outlet; and the blower motor assembly supported in a chassis enclosure; a radially outer inter-stage path between the first and second volute, wherein the second volute is at least partially substantially concentrically nested with the radially outer inter-stage gas path. The impeller is said to be of a one-piece construction.

The present technology is directed towards providing medical devices comprising alternative arrangements of impellers, blowers and/or RPT devices that may ameliorate or reduce some of the known challenges in the art, and manufacturing methods thereof, thus having one or more of improved comfort, cost, efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to apparatus used in the diagnosis, amelioration, treatment or prevention of a respiratory disorder.

Another aspect of the present technology relates to an RPT device having a reduced or compact size (e.g., impeller with a reduced size), while minimising any compromises to noise and/or efficiency.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy such as at a pressure between <NUM>-<NUM> cmH<NUM>O. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a set of impeller blades, each impeller blade including a leading edge and a trailing edge. The impeller also includes a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller. The first shroud includes a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than <NUM>. The first shroud and the second shroud are configured such that the flow passage is narrower in an axial direction at an outer portion of the impeller than at an inner portion of the impeller, and a diameter of the impeller inlet is at least <NUM> % of the diameter of the impeller.

In an example, the first shroud may be substantially non-planar. In an example, the first shroud may include a frusto-conical shape. In an example, the second shroud may be substantially planar. In an example, the leading edge may be inclined by an angle greater than <NUM> degrees with respect to an axis of the motor. In an example, the impeller may comprise a metal. In an example, the impeller may be manufactured by an additive process. In an example, the impeller may comprise a first moulded portion and a second moulded portion fastened together. In an example, the first moulded portion may comprise the first shroud and the set of impeller blades. In an example, the second moulded portion may comprise an impeller hub and the second shroud. In an example, the first moulded portion and the second moulded portion may be fastened together by a snap fit.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy such as at a pressure between <NUM>-<NUM> cmH<NUM>O. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a set of impeller blades, each impeller blade comprising a leading edge and a trailing edge. The impeller also includes a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller. The first shroud includes a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than <NUM>. A thickness of the leading edge and the trailing edge of each impeller blade is less than about <NUM> to improve efficiency of the compact respiratory therapy device.

In an example, the impeller may comprise a metal. In an example, the impeller may be produced by an additive method. In an example, the first shroud may be tapered in a radial direction with respect to an axial direction. In an example, the rotor may include a shaft comprising the same metal as the impeller. In an example, the leading edge and the trailing edge of each impeller blade may comprise an elastomer. In example, each impeller blade may further comprise a rigid material. In an example, the thickness of the leading edge and the trailing edge of each impeller blade may be less than <NUM>.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge. The impeller also includes a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller. The first shroud includes a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than <NUM>, and a leading edge of the periphery of the impeller inlet comprises a cross sectional shape with a radius of at least <NUM>, whereby in use, an air flow entering the impeller is discouraged from detachment at or around the radius.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge. The impeller also includes a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller. The first shroud includes a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and a leading edge of the first shroud comprises a cross sectional shape with a radius of at least <NUM>, whereby in use, an air flow entering the impeller is discouraged from detachment.

In an example, the radius of the leading edge of the first shroud may be greater than <NUM>% of a maximum thickness of a body of the first shroud. In an example, the radius of the leading edge of the first shroud may be greater than the maximum thickness of the body of the first shroud. In an example, the first shroud may be tapered in an axial direction of the motor. In an example, the first shroud may comprise a frusto-conical shape. In an example, the second shroud may be substantially planar.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge. The impeller also includes a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller. The first shroud includes a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and a leading edge of the first shroud comprises a cross sectional shape with a radius of at least <NUM>% of the diameter of the impeller, whereby in use, an air flow entering the impeller is discouraged from detachment.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge. The impeller also includes a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller. The first shroud includes a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and the first shroud comprises a first material and the second shroud comprises a second material, where one of the first and second materials is an elastomer.

In an example, one of the first and second materials may be silicone. In an example, the plurality of impeller blades may comprise silicone at the trailing edge. In an example, the trailing edge may comprise serrations arranged along the trailing edge. In an example, the first shroud may be substantially non-planar. In an example, the first shroud may comprises a frusto-conical shape. In an example, the second shroud may be substantially planar. In an example, the leading edge may be inclined by an angle greater than <NUM> degrees with respect to an axis of the motor.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a first moulded part comprising a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge, and a first shroud comprising a wall defining a periphery of an impeller inlet. The impeller also includes a second moulded part comprising a hub structured for coupling to the rotor and a second shroud. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and each shroud at least partly defines a flow passage through the impeller.

In an example, the first moulded part and the second moulded part may be fastened by a snap fit. In an example, the hub may be press fit onto the rotor and the snap fit may be tightened by the press fit. In an example, the first moulded part and the second moulded part may be welded together. In an example, the first moulded part may further comprise an outer portion of the second shroud, and the second moulded part may further comprise an outer portion of the first shroud. In an example, the second moulded part may further comprise inner portions of the impeller blades. In an example, the inner portions of the impeller blades may be adapted to be received in corresponding openings provided within the impeller blades. In an example, the first moulded part may comprise silicone. In an example, the first moulded part may be overmoulded to the second moulded part.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes: a first moulded part including a plurality of impeller blades, each impeller blade including a leading edge and a trailing edge; a hub structured for coupling to the rotor; and a first shroud comprising a wall defining a periphery of an impeller inlet. The impeller further includes a second moulded part including: a second shroud; and a fastening portion. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and each shroud at least partly defines a flow passage through the impeller.

In an example, the first moulded part may further comprise a plurality of protrusions adapted to engage with the fastening portion of the second moulded part. In an example, each impeller blade may comprise a thickened protrusion adapted to engage with the fastening portion of the second moulded part. In an example, the fastening portion of the second moulded part may comprise a lower portion of the hub with which the hub of the first moulded part is adapted to engage.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes: a first moulded part including a first shroud including a wall defining a periphery of an impeller inlet; a second moulded part including: a hub structured for coupling to the rotor, and a second shroud; and a third moulded part comprising a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and each shroud at least partly defines a flow passage through the impeller.

Another aspect of the present technology relates to a compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy. The device includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes: a first moulded part including: a first shroud comprising a wall defining a periphery of an impeller inlet; and a plurality of impeller blades, each impeller blade comprising a leading edge and a trailing edge; a second moulded part comprising a second shroud; and a third moulded part comprising a hub structured for coupling to the rotor. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than about <NUM>, and each shroud at least partly defines a flow passage through the impeller.

In an example, the second moulded part may further comprise a lower portion of the hub and lower portions of each of the impeller blades. In an example, the first moulded part may further comprise an upper portion of the hub. In an example, the third moulded part may be injection moulded to the first and second moulded parts to fasten the first and second moulded parts to one another.

Another aspect of the present technology relates to an impeller configured to be rotated by a rotor to deliver a flow of air. The impeller includes: a set of impeller blades, each impeller blade comprising a leading edge and a trailing edge; and a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller, the first shroud comprising a wall defining a periphery of an impeller inlet. A diameter of the impeller is less than <NUM>. The impeller comprises a metallic material, and the impeller is manufactured by an additive process.

In one form, the present technology comprises an apparatus or device for treating a respiratory disorder. The apparatus or device may comprise an RPT device <NUM> for supplying pressurised air to the patient <NUM> via an air circuit <NUM> to a patient interface <NUM>.

As shown in <FIG>, a non-invasive patient interface <NUM> in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure <NUM>, a plenum chamber <NUM>, a positioning and stabilising structure <NUM>, a vent <NUM>, one form of connection port <NUM> for connection to air circuit <NUM>, and a forehead support <NUM>. In some forms a functional aspect may be provided by one or more physical components. In some forms, one physical component may provide one or more functional aspects. In use the seal-forming structure <NUM> is arranged to surround an entrance to the airways of the patient so as to facilitate the supply of air at positive pressure to the airways.

An RPT device <NUM> in accordance with one aspect of the present technology comprises mechanical, pneumatic, and/or electrical components and is configured to execute one or more algorithms. The RPT device <NUM> may be configured to generate a flow of air for delivery to a patient's airways, such as to treat one or more of the respiratory conditions described elsewhere in the present document.

In one form, the RPT device <NUM> is constructed and arranged to be capable of delivering a flow of air in a range of -<NUM>/min to +<NUM>/min while maintaining a positive pressure of at least <NUM> cmH<NUM>O, or at least 10cmH<NUM>O, or at least <NUM> cmH<NUM>O.

As shown in <FIG>, the RPT device may have an external housing <NUM>, formed in two parts, an upper portion <NUM> and a lower portion <NUM>. Furthermore, the external housing <NUM> may include one or more panel(s) <NUM>. The RPT device <NUM> comprises a chassis <NUM> that supports one or more internal components of the RPT device <NUM>. The RPT device <NUM> may include a handle <NUM>.

The pneumatic path of the RPT device <NUM> may comprise one or more air path items, e.g., an inlet air filter <NUM>, an inlet muffler, a pressure generator capable of supplying air at positive pressure (e.g., a blower <NUM>), an outlet muffler and one or more transducers, such as pressure sensors and flow rate sensors.

One or more of the air path items may be located within a removable unitary structure which will be referred to as a pneumatic block <NUM>. The pneumatic block <NUM> may be located within the external housing <NUM>. In one form a pneumatic block <NUM> is supported by, or formed as part of the chassis <NUM>.

The RPT device <NUM> may have an electrical power supply <NUM>, one or more input devices <NUM>, a central controller, a therapy device controller, a pressure generator, one or more protection circuits, memory, transducers, data communication interface and one or more output devices. Electrical components <NUM> may be mounted on a single Printed Circuit Board Assembly (PCBA) <NUM>. In an alternative form, the RPT device <NUM> may include more than one PCBA <NUM>.

An RPT device may comprise one or more of the following components in an integral unit. In an alternative form, one or more of the following components may be located as respective separate units.

In one form of the present technology, a pressure generator for producing a flow, or a supply, of air at positive pressure is a controllable blower <NUM>. For example the blower <NUM> may include a brushless DC motor with one or more impellers. The blower may be capable of delivering a supply of air, for example at a rate of up to about <NUM> litres/minute, at a positive pressure in a range from about <NUM> cmH<NUM>O to about <NUM> cmH<NUM>O, or in other forms up to about <NUM> cmH<NUM>O. The blower may be as described in any one of the following patents or patent applications: <CIT>; <CIT>; <CIT>; and <CIT>.

The pressure generator is under the control of the therapy device controller.

In other forms, a pressure generator may be a piston-driven pump, a pressure regulator connected to a high pressure source (e.g. compressed air reservoir), or a bellows.

Examples of impellers according to the present technology are shown in <FIG>. The impeller may be suitable for use in a centrifugal blower, such as those described elsewhere in the present specification.

An impeller <NUM> may comprise one or more of:.

Where the impeller <NUM> comprises a first shroud and a second shroud, the first and second shrouds may be arranged such that an axial distance therebetween may generally decrease towards an outer portion of the impeller in the radial direction.

<FIG> illustrate an impeller <NUM> according to one example of the present technology. As illustrated, the impeller <NUM> includes a plurality of impeller blades <NUM> located between and connected to the first or top shroud <NUM> and the second or bottom shroud <NUM>. In the illustrated example, the bottom shroud <NUM> extends to the hub <NUM> adapted to receive the rotor of the motor.

In the illustrated example, the top shroud <NUM> is substantially non-planar. For example, the top shroud <NUM> may taper in the radial direction with respect to the axial direction of the impeller, e.g., the top shroud <NUM> may comprise a frusto-conical shape. The top shroud <NUM> includes an outer edge defining a diameter D of the top shroud and an inner edge defining a center opening which provides an impeller inlet <NUM>. An impeller inlet wall <NUM> extends along the inner edge to define a periphery of the impeller inlet <NUM>. The free end portion of the inlet wall <NUM> provides a leading edge <NUM> of the impeller inlet <NUM>. In this arrangement, the top shroud <NUM> extends to an outer periphery of the impeller, thus the diameter D of the top shroud is the same as the diameter of the impeller. However in other arrangements, the top shroud <NUM> may not extend to the outer periphery of the impeller, for example only covering a part of the impeller blades.

In the illustrated example, the bottom shroud <NUM> is substantially planar. As illustrated, the outer edge of the bottom shroud <NUM> defines a diameter that is substantially similar, e.g., the same, to the diameter D defined by the outer edge of the top shroud <NUM>. In an example, the diameter D of the impeller is less than about <NUM>. The <NUM> dimension is not intended to be strictly limiting and the skilled person would understand that other diameters in the vicinity of <NUM> would give some beneficial effect.

The top and bottom shrouds <NUM>, <NUM> cooperate to define a flow passage <NUM> therebetween through the impeller. The flow passage <NUM> extends from the impeller inlet <NUM> at an inner portion of the impeller to an impeller outlet <NUM> at an outer portion of the impeller. The flow passage <NUM> may include a plurality of channels, each channel defined at least partly by the top and bottom shrouds <NUM>, <NUM> and impeller blades <NUM>.

In the illustrated example, the flow passage <NUM> defined between the top and bottom shrouds <NUM>, <NUM> is structured to narrow (in a normal direction to the direction of the airflow) from the impeller inlet <NUM> to the impeller outlet <NUM>, i.e., the spacing or distance between the top and bottom shrouds <NUM>, <NUM> lessens or tapers from the impeller inlet to the impeller outlet.

That is, the top and bottom shrouds <NUM>, <NUM> are configured such that the flow passage is narrower in the axial direction at the outer portion of the impeller than at the inner portion of the impeller, i.e., an axial distance between the top and bottom shrouds <NUM>, <NUM> may generally decrease towards the outer portion of the impeller in the radial direction. For example, <FIG> shows exemplary axial distances d1 and d2 between the top and bottom shrouds <NUM>, <NUM>, with d1 along an inner portion of the impeller larger than d2 along an outer portion of the impeller and the axial distance gradually decreasing from d1 to d2 in the radial direction. Additionally, the top and bottom shrouds <NUM>, <NUM> are configured such that the axial distance between them at the outlet of the impeller (i.e., d2) is smaller than the radial dimension of the inlet.

Thus, an impeller according to an aspect of the present technology may comprise a flow passage <NUM> comprising a plurality of channels, each channel configured with a decreasing height along a direction of the air flow therethrough.

An impeller according to the present technology may comprise a relatively large impeller inlet size as a proportion of the impeller diameter D. In one form, the impeller inlet <NUM> may be defined by a periphery of the top shroud <NUM>, such as in <FIG>, where the inlet wall <NUM> of the top shroud <NUM> is shown in the cross section.

In general, it may be a disadvantage to increase a size of the impeller inlet in a centrifugal blower while maintaining other dimensions (e.g., impeller diameter), as such an increase may decrease an effective diameter of the impeller in which pressure using the centrifugal effect may be imparted to the air flowing through the blower. In other words, enlargement of an impeller inlet may result in a configuration wherein insufficient pressure is generated by the blower.

However, for an application such as in RPT devices, where a small size of the device is desirable for aesthetic reasons, convenient bedside placement of the RPT device and portability, a designer may wish to reduce a size of the impeller. However, as an impeller diameter is reduced, a velocity of the air flow through the impeller is increased, adversely affecting noise and efficiency of the impeller, for example caused by changes to an aerodynamic behaviour due to the increase in air velocity.

As described elsewhere, an RPT device may be relatively unique in that it is preferably small and quiet for bedside/nocturnal/sleep-time use, while requiring generation of sufficient pressures and flow rates for respiratory therapy. For use in small, possibly portable, RPT devices, it was found that a decrease in impeller diameter may be accompanied by a relative increase in the impeller inlet diameter.

In one form, the impeller of a diameter D of less than <NUM> may comprise an impeller inlet <NUM>, wherein a diameter (dinlet as shown in <FIG>) of the impeller inlet <NUM> is at least <NUM>% of the diameter D of the impeller. The <NUM>% proportion is not intended to be strictly limiting and the skilled person would understand that other proportions in the vicinity of <NUM>% would give some beneficial effect. In one example, the impeller may comprise a diameter D of <NUM> with an impeller inlet diameter dinlet of <NUM>, <NUM> or <NUM>.

According to another aspect of the present technology, the impeller inlet wall <NUM>, or a periphery of the impeller inlet <NUM>, may comprise a relatively large radius to improve overall impeller and/or blower performance. An increased radius at a portion facing the incoming air flow into the impeller may advantageously lead to improved efficiency, as the air flow remains attached to the inlet wall <NUM>.

In one form, a leading edge of the periphery of the impeller inlet <NUM>, e.g., the leading edge <NUM> at the free end portion of the inlet wall <NUM> of the top shroud <NUM> (as best shown in <FIG>), comprises a cross sectional shape with a radius of at least <NUM>. In another form, a radius of the leading edge of the first or top shroud <NUM> is greater than <NUM>% of the maximum thickness of the body of the first shroud <NUM>, such as greater than <NUM>%, <NUM>% or <NUM>%. In another form, a radius of the leading edge <NUM> of the first or top shroud <NUM> is greater than the maximum thickness of a body of the first shroud <NUM>. In another form, a leading edge of the first or top shroud <NUM> comprises a cross sectional shape with a radius of at least <NUM>% of the diameter D of the impeller. In use, an air flow entering the impeller at the impeller inlet <NUM> is discouraged from detachment at or around the radius, e.g., to reduce noise and improve efficiency.

The impeller <NUM> may comprise a plurality of impeller blades <NUM>. In the illustrated example, the impeller includes <NUM> blades <NUM>. However, it should be appreciated that the impeller may include other suitable numbers of blades, e.g., <NUM> or more blades, e.g., <NUM>-<NUM> blades, e.g., <NUM> blades, <NUM> blades, <NUM> blades.

Each impeller blade <NUM> extends from the hub <NUM> towards the outer edge of the impeller. Each impeller blade may be connected to the top and bottom shrouds <NUM>, <NUM>. Each impeller blade comprises a leading edge <NUM> and a trailing edge <NUM>. It should be noted that the terms 'leading edge' and 'trailing edge' are to be understood akin to its usage in aeronautics, referring to a portions of a wing, rather than a narrow geometric sense of an 'edge'.

For example, a 'leading edge' may refer to a part of the impeller blade that generally first contacts the air coming into the impeller. Similarly, a 'trailing edge' may refer to a part of the impeller blade that generally last contacts the air as it leaves the impeller.

In the illustrated example, the impeller blades <NUM> are sandwiched between the top and bottom shrouds <NUM>, <NUM>. As illustrated, each blade <NUM> is overlapped by the top shroud <NUM> such that a first edge <NUM> along an outer portion of the blade is in contact with the top shroud <NUM> and the leading edge <NUM> along an inner portion of the blade is exposed through the impeller inlet <NUM>, i.e., leading edge <NUM> extends between the inlet wall <NUM> and the hub <NUM> defining the inlet <NUM> into the impeller. Each blade <NUM> is overlapped by the bottom shroud <NUM> such that a second edge <NUM> is in contact with the bottom shroud <NUM> and hub <NUM> along its entire length. The trailing edge <NUM> is exposed through the impeller outlet <NUM> between the outer ends of the top and bottom shrouds <NUM>, <NUM>.

In the illustrated example, each blade <NUM> extends to the outer edges of the top and bottom shrouds <NUM>, <NUM>, e.g., the blades <NUM> do not extend beyond the top and bottom shrouds <NUM>, <NUM>. In alternative examples, the blades <NUM> may extend beyond or extend short of the outer edges of the top and bottom shrouds <NUM>, <NUM>.

According to one aspect of the present technology, the leading edge <NUM> and/or the trailing edge <NUM> of an impeller blade <NUM> may be very thin, such that turbulence and noise is reduced at the inlet and outlet of the impeller. In an example, the thickness of the leading edge <NUM> and/or the trailing edge <NUM> of an impeller blade <NUM> may be less than about <NUM>, e.g., less than about <NUM>, such as measured at its thinnest portion, or measured at its outermost portion (i.e., most downstream portion). The <NUM> is not intended to be strictly limiting and the skilled person would understand that other thicknesses the vicinity of <NUM> would give some positive effect. Furthermore, uniquely to RPT devices, some impeller designs may be such that a seemingly small reduction in a size of the leading (and/or trailing) edge may have a positive effect on the air flow of the impeller and efficiency of the RPT device.

In an example, the cross-sectional thickness of each blade <NUM> may be variable or tapered, e.g., along at least a portion of its length in plan view. For example, as shown in <FIG>, an outer portion of each blade <NUM> may include a cross-sectional thickness that tapers towards the trailing edge <NUM>.

Also, as shown in <FIG>, each blade <NUM> may be curved and/or provide curved exterior surfaces, e.g., along at least a portion of its length in plan view. For example, as shown in <FIG>, an outer portion of each blade <NUM> may provide curved surfaces <NUM> along its length towards the trailing edge <NUM>, e.g., to provide a smooth air flow passage to reduce turbulence and hence noise.

Further, as shown in <FIG>, the flow passage defined between adjacent blades <NUM> is structured to enlarge, e.g., along at least a portion of its length in plan view. For example, as shown in <FIG>, the flow passage defined between adjacent blades <NUM> is structured to enlarge towards the trailing edges <NUM>, e.g., to increase pressure.

An impeller blade <NUM> may be inclined, as shown in <FIG>, <FIG> or the cross sections shown in <FIG>. For example, the leading edge <NUM> of each blade <NUM> may be inclined, e.g., by an angle greater than <NUM> degrees, with respect to an axis of the hub <NUM> or motor.

In the example of <FIG>, the trailing edge <NUM> extends substantially parallel to an axis of the hub <NUM>.

In some forms, as shown in <FIG>, the impeller blade <NUM> may comprise one or more serrations, e.g., the leading edge <NUM> and/or the trailing edge <NUM> may comprise one or more serrations arranged along the leading edge <NUM> and/or the trailing edge <NUM>. Some examples of potentially suitable arrangements of leading edge and/or trailing edge serrations may be found on <CIT>.

Many prior art impellers, particularly in the field of respiratory pressure therapy devices, have been manufactured by injection moulding a polymer material. Typical reasons may have included (but not limited to):.

As a consequence of using injection moulding, particular impeller geometries may have been either extremely difficult to achieve, or simply not possible using injection moulding only. For example, an impeller employing curved and swept blades, as well as top and bottom shrouds, may be extremely difficult to manufacture using an injection moulding process. That is, once the component had been moulded, it could not be extracted from the moulding tool, as the tool and the component would now be intertwined.

In another example, an injection moulded plastic component may require a minimum wall thickness, such that the molten plastic being injected may be able to flow sufficiently within the mould without requiring excessive pressures.

In some examples, an impeller comprising one or more of the aspects described herein may be manufactured by employing alternative manufacturing methods or constructions, while overcoming some of the disadvantages previously associated with such methods.

In one aspect, an impeller according to the present technology may be produced by an additive technique, sometimes referred to as "three-dimensional (3D) printing", potentially using a metallic material such as titanium, aluminium or stainless steel.

In many applications, even in some instances of RPT devices, a metallic impeller may have a disadvantage over a polymer impeller due to the increased rotational inertia. As alluded to earlier, a higher rotational inertia of an impeller may require an increased capability from a motor driving the impeller, as the requisite torque to accelerate or decelerate the impeller is increased. In turn, the motor may increase in size, and requirements for the power supply and/or a battery may accordingly be increased.

However, for a relatively small impeller, some of these problems may be ameliorated, whereby use of a metallic material becomes more feasible. As a diameter of the impeller decreases, the corresponding rotational inertia decreases as the square of the radius: I ∝ mr<NUM>, where I refers to rotational inertia, m to mass of the impeller and r is the radius of the impeller. This is effectively a power of <NUM> dependency of rotational inertia on radius, since for a given material and thickness the mass of the impeller also varies as the square of the radius.

Thus, advantageously, it was found that for the present application and size, additive manufacturing techniques using a metallic material may be particularly suitable such that high-efficiency geometry such as those described herein may be achieved.

In some instances, a material (e.g., metallic material) with the same/similar coefficient of expansion as a rotor (e.g., motor shaft) may be chosen (e.g., the shaft and the impeller may comprise the same metal or metallic material), such that if the impeller is press fit onto the rotor, any thermal expansion would occur uniformly between the two joined, rotating components. This may help to preserve integrity of an interference fit despite variations in temperature, which may vary more within a motor than for example in ambient air.

According to one aspect of the present technology, such as shown in <FIG>, an impeller <NUM> may comprise multiple portions.

In some forms, one portion may comprise a different material to another portion. For instance, a first portion may comprise a deformable, resilient material and a second portion may comprise a rigid material. In an example, the rigid material may be a plastic material, and the resilient material may be an elastomeric material such as a silicone material.

In the example shown in <FIG>, a first moulded part or portion, i.e., a first impeller portion <NUM>-<NUM>, may be structured and arranged to be coupled to a second moulded part or portion, i.e., second impeller portion <NUM>-<NUM>, to produce the impeller <NUM>. The first impeller portion <NUM>-<NUM> may comprise a deformable, resilient material (e.g., an elastomeric material such as silicone) that may be coupled with the second impeller portion <NUM>-<NUM> comprising a rigid material (e.g., rigid plastic). For example, a manufacturing process may first produce (e.g., mould) the second impeller portion <NUM>-<NUM>, onto which the first impeller portion <NUM>-<NUM> may be overmoulded. Other forms of coupling, such as chemical bonding or mechanical bonding, may be suitable that are not overmoulded.

As illustrated, the first impeller portion <NUM>-<NUM> comprises the plurality of impeller blades <NUM>, a portion of the top shroud <NUM> (i.e., an inner or first portion <NUM>-<NUM> of the top shroud which comprises the inlet wall <NUM> defining the periphery of the impeller inlet <NUM>), and a portion of the bottom shroud <NUM> (i.e., an outer or first portion <NUM>-<NUM> of the bottom shroud). The second impeller portion <NUM>-<NUM> comprises a portion of the top shroud <NUM> (i.e., an outer or second portion <NUM>-<NUM> of the top shroud), the hub <NUM> structured for coupling to the rotor, a portion of the bottom shroud <NUM> (i.e., an inner or second portion <NUM>-<NUM> of the bottom shroud), and inner blade portions <NUM>. The inner blade portions <NUM> are adapted to be received in corresponding openings <NUM> provided within the impeller blades <NUM>, e.g., to add rigidity to the impeller blades <NUM>.

When the first impeller portion <NUM>-<NUM> is overmoulded to the second impeller portion <NUM>-<NUM> to produce the impeller <NUM>, the inner portion <NUM>-<NUM> and the outer portion <NUM>-<NUM> cooperate to form the top shroud <NUM>, the outer portion <NUM>-<NUM> and the inner portion <NUM>-<NUM> cooperate to form the bottom shroud <NUM>, and the inner blade portions <NUM> add interior rigidity to the impeller blades <NUM>, i.e., inner blade portions <NUM> add a rigid material to the impeller blades <NUM>. In such arrangement, the impeller blades <NUM> and the leading and trailing edges <NUM>, <NUM> thereof comprise an elastomer material (e.g., silicone), and the hub <NUM> comprises a rigid material for coupling to the rotor.

By such a construction, an impeller may be produced with the desired, advantageous aerodynamic features described herein, which can be injection moulded. That is, using such a construction, the manufacturer may be able to withdraw a 'core' of the injecting moulding tool, as the first impeller portion <NUM>-<NUM> (e.g., comprising silicone) would be able to resiliently deform to allow removal of the injection moulding tool. Further advantageously, such a material (e.g., silicone) of the first impeller portion <NUM>-<NUM> may allow manufacture of thinner wall sections than plastic, thus enabling manufacture for example of the thin impeller blade leading edge <NUM> and/or trailing edge <NUM> described above.

Also, a strategic use of such a deformable, resilient material, rather than construction of an impeller entirely from a deformable, resilient material, may help to manufacture an impeller wherein an overall structural integrity is sufficient for durability as well as limiting deformation in operation.

In other forms, an impeller may comprise multiple portions, each not necessarily comprising different materials to each other.

In the example shown in <FIG>, the first impeller portion <NUM>-<NUM> and the second impeller portion <NUM>-<NUM> may be separately moulded and assembled or fastened together. In an example, the first and second portions may each comprise a rigid material (e.g., rigid plastic, such as PEEK, also known as polyetheretherketone). In another example, the first portion may comprise a deformable, resilient material (e.g., an elastomeric material such as silicone) and the second portion may comprise a rigid material (e.g., rigid plastic). For example, the first portion <NUM>-<NUM> (i.e., the first moulded part or portion) may comprise the top shroud <NUM>, the impeller blades <NUM>, and a first fastening portion <NUM>. The second portion <NUM>-<NUM> (i.e., the second moulded part or portion) may comprise the hub <NUM>, the bottom shroud <NUM>, and a second fastening portion <NUM>. The first impeller portion <NUM>-<NUM> and the second impeller portion <NUM>-<NUM> are fastened together by assembling the first fastening portion <NUM> to the second fastening portion <NUM>.

In the illustrated example, the first fastening portion <NUM> includes a hub portion <NUM>-<NUM> and radially extending projections <NUM>-<NUM> spaced about the perimeter of the hub portion <NUM>-<NUM> (e.g., see <FIG>). The second fastening portion <NUM> includes an annular slot <NUM>-<NUM> about the hub <NUM> adapted to receive the hub portion <NUM>-<NUM> of the first fastening portion <NUM> when assembled, and the second fastening portion <NUM> includes radially extending slots <NUM>-<NUM> adapted to receive respective projections <NUM>-<NUM> of the first fastening portion <NUM> when assembled, e.g., to prevent relative rotation. However, it should be appreciated that the first and second fastening portions <NUM>, <NUM> may comprise other fastening configurations to fasten, interlock, or otherwise interface the first and second impeller portions.

The two portions <NUM>-<NUM> and <NUM>-<NUM> may be fastened or secured together to produce the impeller <NUM>, such as by snap fit, gluing, welding or any number of other suitable methods. Still further, in some forms, the two portions <NUM>-<NUM> and <NUM>-<NUM> may be arranged such that coupling the assembled impeller <NUM> onto the motor (e.g., via motor shaft) further strengthens the bonding between the portions of the impeller <NUM>. For example, when the hub <NUM> of impeller <NUM> is coupled to the rotor or motor shaft (e.g., by a press fit), the fastening (e.g., snap-fit) between the two portions <NUM>-<NUM> and <NUM>-<NUM> may be assisted and tightened by such hub coupling, e.g., the snap-fit fastening may be tightened by the press-fit coupling of the hub to the rotor.

In another example, as shown in <FIG>, the first impeller portion <NUM>-<NUM> (i.e., the first moulded part or portion) may comprise the top shroud <NUM>, the impeller blades <NUM>, the hub <NUM>, and a first fastening portion <NUM>. The second impeller portion <NUM>-<NUM> (i.e., the second moulded part or portion) may comprise the bottom shroud <NUM> (e.g., substantially planar disc) and a second fastening portion <NUM>. In the illustrated example, the first fastening portion <NUM> comprises a plurality of protrusions or pips <NUM>-<NUM> extending from the flat lower surface of the impeller blades <NUM> and/or the hub <NUM>, and the second fastening portion <NUM> comprises a plurality of holes or slots <NUM>-<NUM> in the bottom shroud <NUM>. The two portions <NUM>-<NUM> and <NUM>-<NUM> may be coupled by aligning and engaging the plurality of protrusions or pips <NUM>-<NUM> into respective holes or slots <NUM>-<NUM> and then fastened or secured together, e.g., by heat stake. The protrusions <NUM>-<NUM> and corresponding holes <NUM>-<NUM> may include circular and/or non-circular shapes, e.g., exemplary figures show combination of circular and non-circular shapes for the protrusions/holes which may be arranged along similar or different portions of the impeller relative to one another (e.g., protrusion/hole along radially inner portion of impeller blade, protrusion/hole along radially outer portion of impeller blade, protrusion/hole along hub). It should be appreciated that <FIG> are exemplary and the protrusions/holes may include any suitable combination of shapes, sizes, and arrangements to facilitate fastening and alignment of the two portions <NUM>-<NUM> and <NUM>-<NUM>. In an example, an increased number of protrusions/holes may be at least partially determinative of the strength of the joint.

In an example, as shown in <FIG>, a relatively sharp end of the blade tip of each impeller blade <NUM> may be filled in to form a thicker protrusion <NUM>-<NUM> adapted to engage within a corresponding slot or cut-away <NUM>-<NUM> in the edge of the bottom shroud <NUM>. Such arrangement avoids construction of a sharp blade tip to facilitate manufacture, e.g., facilitate molding.

<FIG> show another example of an impeller comprising two impeller portions. In the illustrated example, the first impeller portion <NUM>-<NUM> (i.e., the first moulded part or portion) may comprise the top shroud <NUM>, an upper portion <NUM>-<NUM> of the hub <NUM>, and an upper portion <NUM>-<NUM> of each of the plurality of impeller blades <NUM>. In the illustrated example, the second impeller portion <NUM>-<NUM> (i.e., the second moulded part or portion) may comprise the bottom shroud <NUM>, a lower portion <NUM>-<NUM> of the hub <NUM>, and a lower portion <NUM>-<NUM> of each of the plurality of impeller blades <NUM>. The first impeller portion <NUM>-<NUM> and the second impeller portion <NUM>-<NUM> provide generally planar joining geometry or planar surfaces that are fastened together, e.g., by gluing or welding the upper portion <NUM>-<NUM> of the hub <NUM> to the lower portion <NUM>-<NUM> of the hub <NUM>, and by gluing or welding the upper portion <NUM>-<NUM> of each of the plurality of impeller blades <NUM> to a respective one of the lower portion <NUM>-<NUM> of each of the plurality of impeller blades <NUM>.

In such example, the first and second portions <NUM>-<NUM>, <NUM>-<NUM> may comprise line-of-draw and may be injection molded with relatively simple, rotating tools. For example, the more complex first portion <NUM>-<NUM> may comprise rotating-while-moving-linearly core to form the flow passage inlets and line-of-draw for the remainder of the flow passage, and the simpler second portion <NUM>-<NUM> may comprise the bottom shroud (e.g., substantially planar disc) with line-of-draw for partial blades.

In an example, as shown in <FIG>, the upper portion <NUM>-<NUM> of the hub <NUM> of the first portion <NUM>-<NUM> may comprise a cylindrical protrusion <NUM>-<NUM> adapted to engage within the central opening <NUM>-<NUM> provided by the lower portion <NUM>-<NUM> of the hub <NUM> of the second portion <NUM>-<NUM>. Such arrangement provides a concentric alignment detail (i.e., cylindrical locating interfaces between the first and second portions <NUM>-<NUM>, <NUM>-<NUM>) to the hub to facilitate alignment and concentricity of the first and second impeller portions <NUM>-<NUM>, <NUM>-<NUM> when fastened to one another.

In another example, as shown in <FIG>, the lower portion <NUM>-<NUM> of the hub <NUM> of the second portion <NUM>-<NUM> may comprise a protrusion <NUM>-<NUM> (e.g., generally cylindrical protrusion) adapted to engage within an opening <NUM>-<NUM> provided in the upper portion <NUM>-<NUM> of the hub <NUM> of the first portion <NUM>-<NUM>. Such arrangement provides a concentric alignment to the hub to facilitate alignment of the first and second portions <NUM>-<NUM>, <NUM>-<NUM> when fastened to one another.

It will of course be understood that this would not be limited to impellers consisting of two portions, however any number of portions may be assembled together to produce an impeller.

For example, in an alternative example, an impeller may comprise three impeller portions that are fastened or secured together to produce the impeller. For example, as shown in <FIG>, a first impeller portion <NUM>-<NUM> may comprise the bottom shroud <NUM> and the hub <NUM> structured for coupling to the rotor, a second impeller portion <NUM>-<NUM> may comprise the plurality of impeller blades <NUM> (e.g., <NUM> impeller blades), and a third impeller portion <NUM>-<NUM> may comprise the top shroud <NUM>. In an example, each of the first, second, and third impeller portions <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> may comprise a molded construction of plastic material. In an exemplary first step, using a fixture, the first and second impeller portions <NUM>-<NUM>, <NUM>-<NUM> may be assembled to one another, e.g., the plurality of impeller blades <NUM> may be secured (e.g., laser or sonic weld) to the bottom shroud <NUM> and the hub <NUM>. In an exemplary second step, using a second fixture, the third impeller portion <NUM>-<NUM> may be assembled to the assembled first and second impeller portions <NUM>-<NUM>, <NUM>-<NUM>, e.g., the top shroud <NUM> may be secured (e.g., laser or sonic weld) to the assembled bottom shroud <NUM>, hub, <NUM> and impeller blades <NUM>.

In another example, as shown in <FIG>, and <FIG>, the impeller may comprise a three-part injection molded construction. For example, the first impeller portion <NUM>-<NUM> (i.e., the first moulded part or portion) may comprise the top shroud <NUM>, an upper portion <NUM>-<NUM> of the hub <NUM>, and an upper portion <NUM>-<NUM> of each of the plurality of impeller blades <NUM>. In the illustrated example, the second impeller portion <NUM>-<NUM> (i.e., the second moulded part or portion) may comprise the bottom shroud <NUM>, a lower portion <NUM>-<NUM> of the hub <NUM>, and a lower portion <NUM>-<NUM> of each of the plurality of impeller blades <NUM>. In the illustrated example, the third impeller portion <NUM>-<NUM> (i.e., the third moulded part or portion) may comprise a cylindrical hub portion <NUM>-<NUM> of the hub <NUM>. In an exemplary first step, the first and second portions <NUM>-<NUM> and <NUM>-<NUM> may be engaged or interlocked by aligning and engaging fastening portions provided to the first and second portions <NUM>-<NUM> and <NUM>-<NUM>, e.g., aligning and engaging plurality of protrusions or pips <NUM>-<NUM> provided to the first portion <NUM>-<NUM> into respective holes or slots <NUM>-<NUM> provided to the second portion <NUM>-<NUM>, e.g., as described above. In an exemplary second step, the third portion <NUM>-<NUM> may be injection molded to the first and second portions <NUM>-<NUM> and <NUM>-<NUM> to fasten the first and second portions <NUM>-<NUM> and <NUM>-<NUM> to one another, e.g., cylindrical hub portion <NUM>-<NUM> injection molded between the upper and lower portions <NUM>-<NUM>, <NUM>-<NUM> to form the hub <NUM> and fasten the first and second portions <NUM>-<NUM> and <NUM>-<NUM>.

<FIG> shows a blower <NUM> for an RPT device including impellers <NUM> according to one aspect of the present technology. In the illustrated example, the blower <NUM> includes a two-stage design structured and configured for producing a flow, or a supply, of air at positive pressure, e.g., in the range of <NUM>-<NUM> cmH<NUM>O. In an example, the RPT device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH<NUM>O at an overall sound power level of less than <NUM> dB(A) thereby reducing any disturbance to a quality of sleep for the patient. However, in alternative examples, the blower may include a single stage design, a three stage design, or four or more stage designs.

As shown, the blower <NUM> includes a housing <NUM> including an axial air inlet (blower inlet) <NUM> and axial air outlet (blower outlet) <NUM> between which are located two stages with corresponding impellers <NUM>, i.e., a first impeller <NUM> positioned on one side of the motor <NUM> and a second impeller <NUM> positioned on the other side of the motor <NUM>. The motor <NUM> includes a rotor <NUM> to which the impellers <NUM> are coupled. The impellers <NUM> are configured to be rotated by the rotor <NUM> to deliver a flow of air from the inlet <NUM> toward the outlet <NUM>. However, other suitable impeller arrangements are possible. Each impeller <NUM> may be followed by a set of stator vanes structured and configured to direct the air flow to the next stage or outlet.

In an example, the housing <NUM> may comprise a plurality of housing portions (e.g., first housing part including inlet <NUM>, second housing part including outlet <NUM>, and intermediate housing parts (e.g., stationary components providing stator vanes to direct air flow) that are connected to one another (e.g., welded) to a form a substantially sealed structure.

Further examples and details of the blower are described in PCT Patent Application Publication No. <CIT>.

According to one aspect of the present technology, a portion of the housing <NUM> adjacent each impeller <NUM> may include a radius that substantially corresponds to the radius at the leading edge <NUM> of the impeller inlet wall <NUM> of the impeller <NUM>. For example, as best shown on <FIG>, a portion of the housing <NUM> adjacent the perimeter of the blower inlet <NUM> includes a generally curved surface, e.g., concave surface <NUM>, spaced from and adjacent the generally curved surface, e.g., convex surface <NUM>, provided at the leading edge <NUM> of the impeller inlet wall <NUM>. In an example, such generally concave surface <NUM> of the housing <NUM> includes a radius that substantially corresponds to a radius of the generally convex surface <NUM> provided at the leading edge <NUM> of the impeller inlet wall <NUM>.

The substantially corresponding radiusses, the configuration of the curved channel <NUM> formed between the surfaces <NUM>, <NUM> of the housing <NUM> and the impeller <NUM>, and such curved channel <NUM> terminating at a point where the tangent would point generally downwards (i.e., towards the impeller as approximated by the short arrow A1 in <FIG>) helps re-circulated flow (indicated by the long arrow A2 in <FIG>) smoothly enter the impeller inlet <NUM>. That is, the curved channel <NUM> formed by corresponding curved surfaces <NUM>, <NUM> of the housing <NUM> and the impeller <NUM> smoothly directs re-circulated flow into the impeller inlet <NUM>.

Flow rate: The volume (or mass) of air delivered per unit time. Flow rate may refer to an instantaneous quantity. In some cases, a reference to flow rate will be a reference to a scalar quantity, namely a quantity having magnitude only. In other cases, a reference to flow rate will be a reference to a vector quantity, namely a quantity having both magnitude and direction. Flow rate may be given the symbol Q. `Flow rate' is sometimes shortened to simply 'flow' or 'airflow'.

Patient: A person, whether or not they are suffering from a respiratory condition.

Pressure: Force per unit area. Pressure may be expressed in a range of units, including cmH2O, g-f/cm2 and hectopascal. <NUM> cmH2O is equal to <NUM>-f/cm2 and is approximately <NUM> hectopascal. In this specification, unless otherwise stated, pressure is given in units of cmH2O.

Respiratory Pressure Therapy (RPT): The application of a supply of air to an entrance to the airways at a treatment pressure that is typically positive with respect to atmosphere.

Ventilator. A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.

Resilience: Ability of a material to absorb energy when deformed elastically and to release the energy upon unloading.

Resilient: Will release substantially all of the energy when unloaded. Includes e.g. certain silicones, and thermoplastic elastomers.

Hardness: The ability of a material per se to resist deformation (e.g. described by a Young's Modulus, or an indentation hardness scale measured on a standardised sample size).

Stiffness (or rigidity) of a structure or component: The ability of the structure or component to resist deformation in response to an applied load. The load may be a force or a moment, e.g. compression, tension, bending or torsion. The structure or component may offer different resistances in different directions.

Floppy structure or component: A structure or component that will change shape, e.g. bend, when caused to support its own weight, within a relatively short period of time such as <NUM> second.

Rigid structure or component: A structure or component that will not substantially change shape when subject to the loads typically encountered in use. An example of such a use may be setting up and maintaining a patient interface in sealing relationship with an entrance to a patient's airways, e.g. at a load of approximately <NUM> to <NUM> cmH<NUM>O pressure.

The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present technology is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

The terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Although the technology herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. For example, although the terms "first" and "second" may be used, unless otherwise specified, they are not intended to indicate any order but may be utilised to distinguish between distinct elements. Furthermore, although process steps in the methodologies may be described or illustrated in an order, such an ordering is not required. Those skilled in the art will recognize that such ordering may be modified and/or aspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be made to the illustrative examples and that other arrangements may be devised without departing from the scope of the appended claims.

Claim 1:
A compact respiratory therapy device (<NUM>) suitable for use by a patient during sleep to provide respiratory pressure therapy, the device (<NUM>) comprising:
a housing (<NUM>);
an inlet;
an outlet;
a motor (<NUM>) including a rotor (<NUM>);
an impeller (<NUM>) configured to be rotated by the rotor (<NUM>) to deliver a flow of air from the inlet toward the outlet, the impeller (<NUM>) comprising:
a first moulded part (<NUM>-<NUM>) comprising
a plurality of impeller blades (<NUM>), each impeller blade comprising a leading edge (<NUM>) and a trailing edge (<NUM>); and
a first shroud (<NUM>) comprising a wall defining a periphery of a center opening of the impeller (<NUM>), the center opening providing an impeller inlet (<NUM>) of a flow passage through the impeller (<NUM>); and
a second moulded part (<NUM>-<NUM>) comprising a hub (<NUM>) structured for coupling to the rotor (<NUM>) and a second shroud (<NUM>),
wherein the compact respiratory therapy device (<NUM>) is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between <NUM>-<NUM> cmH2O at an overall sound power level of less than <NUM> dB (A) thereby reducing any disturbance to a quality of sleep for the patient, and
wherein:
a diameter of the impeller (<NUM>) is less than about <NUM>,
each shroud (<NUM>, <NUM>) at least partly defines a flow passage through the impeller (<NUM>), and
the first moulded part (<NUM>-<NUM>) and the second moulded part (<NUM>-<NUM>) are separately moulded and assembled together, or the second moulded part (<NUM>-<NUM>) comprises a different material than the first moulded part (<NUM>-<NUM>) and is overmoulded to the first moulded part (<NUM>-<NUM>).