Patent Description:
Blowers are frequently utilized in outdoor applications, such as to blow leaves and other debris. Homeowners frequently utilized such blowers to clean their yards and outdoor spaces. The types of blowers can vary between backpack-style blowers and handheld blowers, as well as between gas-powered and electric blowers. Electric blowers can be corded and plugged into electrical outlets, or can be cordless and battery powered. A blower according to the preamble of claim <NUM> is known from <CIT>.

One issue with known blowers is the noise level that is generated by the blower during operation. A quieter blower can be produced simply by reducing the power and performance level of the blower, but the resulting product is not desirable to the customer due to the lack of performance.

Accordingly, improved blowers which include noise reduction features while not having diminished performance are desired in the art. In particular, blowers which include both reduced noise generation and improved performance characteristics would be advantageous.

According to the invention, a blower as defined in claim <NUM> is provided. The blower may in exemplary embodiments be a handheld blower. The blower may in exemplary embodiments be a battery powered blower.

In accordance with some embodiments, the blower further includes an inlet muffler provided at the inlet end. The inlet muffler includes a plurality of inlet ports, each of the plurality of inlet ports including a peripheral surface defining a port aperture therethrough. At least one of the plurality of inlet ports further includes a damper material provided on the peripheral surface and further defining the port aperture therethrough. In particular embodiments two or more inlet ports of the plurality of inlet ports further includes damper material provided on the peripheral surface and further defining the respective port aperture therethrough.

In accordance with the invention, the blower includes a main body defining an airflow path therethrough, the main body extending between and defining an inlet end and an outlet end. The blower further includes a fan assembly disposed within the main body. The fan assembly includes an axial fan, a motor rotatably connected to the fan, and an outer housing surrounding the fan and the motor. The blower further includes a damper liner, the damper liner disposed within the main body downstream of the outer housing along the airflow path. Further, at least one air gap is defined between the damper liner and the main body.

In accordance with some embodiments, the main body includes an inlet portion and an outlet portion, the inlet portion including the inlet end, the outlet portion including the outlet end. The outlet portion extends along a longitudinal axis, and the inlet portion comprises a curvilinear portion which extends along a curvilinear path relative to the longitudinal axis.

In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention which is defined by the appended claims.

Referring now to <FIG>, embodiments of blowers <NUM> in accordance with the present disclosure are provided. Blowers <NUM> in accordance with the present disclosure advantageously include improved noise reduction features, while also maintaining or having improved performance features. For example, in some exemplary embodiments, a blower <NUM> in accordance with the present disclosure produces at least <NUM> CFM, such as at least <NUM><NUM>/h (<NUM> CFM) flow rate at <NUM>/h (<NUM> mph) velocity while keeping the sound at or below <NUM> dB(A), such as at or below 60dB(A), at <NUM> feet (i.e. using the ANSI <NUM> foot test, ANSI/OPEI B175. <NUM>-<NUM> (amendment published December <NUM>, <NUM>, and/or ISO <NUM>, second edition <NUM>-<NUM>-<NUM>). In exemplary embodiments, a blower <NUM> in accordance with the present disclosure is a battery powered, handheld blower <NUM>. In exemplary embodiments, the battery is a <NUM>-volt (nominal) battery. The blower <NUM> may be configured to receive batteries of various sizes, shapes, and/or power capacities.

Referring now to <FIG>, a blower <NUM> in accordance with the present disclosure includes a main body <NUM>. A handle <NUM> may be connected to and extend from the main body <NUM>. A trigger <NUM> may be included in the handle <NUM>. The trigger <NUM> may be operable to cause operation of the blower <NUM> by activating and deactivating a motor <NUM> of the blower <NUM>. The trigger <NUM> can include variable speed selectivity, allowing the operator to variably control the power of the blower <NUM> within a preset range of speeds.

A battery <NUM> may be removably connected to the blower <NUM> to power the blower <NUM>, and specifically the motor <NUM> thereof. A battery mount <NUM> may be defined in the main body <NUM>, and the battery <NUM> may be removably connectable to the battery mount <NUM>. When connected in and to the battery mount <NUM>, the battery <NUM> may provide a source of power to the blower <NUM>, and specifically the motor <NUM> thereof. Battery mount <NUM> may, for example, provide an electrical connection between the battery <NUM> and the motor <NUM>.

Main body <NUM> defines an airflow path <NUM> therethrough. The airflow path <NUM> extends between and defines an inlet end <NUM> and an outlet end <NUM> of the main body <NUM>. Airflow along the airflow path <NUM> may flow into the main body <NUM> through the inlet end <NUM> and be exhausted from the main body <NUM> through the outlet end <NUM> when the blower <NUM> is operated as a blower. In one or more embodiments, the outlet end <NUM> of the main body can be angularly offset from the airflow path <NUM> by an angle, αF, as measured between a plane, P<NUM>, oriented normal to the airflow path <NUM>, and a plane, P<NUM>, defined by the outlet end <NUM>. In an embodiment, αF can be at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°.

The main body <NUM> can include stabilizing elements <NUM> and <NUM> disposed on an underside to prevent the blower <NUM> from falling or rolling over when rested on the ground. In an embodiment, at least one of the stabilizing elements <NUM> and <NUM> can define an opening, e.g., opening <NUM>, to allow the operator store the blower <NUM> on a member, e.g., a hook.

Main body <NUM> may include an inlet portion <NUM>, which may include and define the inlet end <NUM>, and may include an outlet portion <NUM>, which may include the outlet end <NUM>. In one or more embodiments, the inlet portion <NUM> may be removably coupled with the outlet portion <NUM>. For example, in some embodiments the inlet portion <NUM> may be threadably coupled to the outlet portion <NUM>. In embodiments, the inlet portion <NUM> may be coupled with the outlet portion <NUM>, for example, through a non-threaded engagement, such as for example, a bayonet connection, a nonthreaded connector such as one or more pin(s), a clasp, rotatable lever, a latch (e.g., exemplary latch <NUM> illustrated in <FIG> and <FIG>), or any combination thereof. The latch <NUM> may be attached to the inlet portion <NUM>, outlet portion <NUM>, or both and selectively secure the inlet portion <NUM> and outlet portion <NUM> together. In the illustrated embodiment, the latch <NUM> is a pivotable latch pivotally coupled with the inlet portion <NUM>. The latch <NUM> can include a pivotable body <NUM> with an engagement member (not illustrated) configured to engage with a mating component <NUM> on the outlet portion <NUM>. In certain instances, the pivotable body <NUM> of the latch <NUM> may be pivotally coupled with the outlet portion <NUM> and engageable with mating component(s) <NUM> on the inlet portion <NUM>. In an embodiment, the latch <NUM> may be spring biased to a locked configuration to facilitate easier connecting. For example, attaching the inlet and outlet portions <NUM> and <NUM> may be performed by aligning the portions <NUM> and <NUM> and applying combining force therebetween. The latch <NUM> can automatically receive a mating component and detachably couple the portions <NUM> and <NUM> together. In another embodiment, the latch can be essentially free of a spring biasing member. The latch <NUM> can be disposed on a lateral side of the blower <NUM>, a top side of the blower <NUM>, a bottom side of the blower <NUM>, or anywhere between.

In one or more embodiments, the blower <NUM> can include a single latch <NUM>. In other embodiments, the blower <NUM> can include a plurality of latches <NUM>, such as at least two latches <NUM>, at least three latches <NUM>, or at last four latches <NUM>. In an embodiment, the plurality of latches <NUM> can include same, or similar, type latches. In another embodiment, at least two of the plurality of latches <NUM> can include different-type latches or be operatively coupled to different components of the blower <NUM>, e.g., one latch <NUM> can be pivotally coupled to the inlet portion <NUM> and one latch <NUM> can be pivotally coupled to the outlet portion <NUM>.

The inlet portion <NUM> may house a fan assembly <NUM>, as discussed herein. The outlet portion <NUM> may be downstream of the fan assembly <NUM> in the direction of the airflow path <NUM>. In an embodiment, a technician may access the fan assembly <NUM> or other components of the blower <NUM> by removing the outlet portion <NUM> from the inlet portion <NUM> using the previously described latch(es) <NUM>.

A longitudinal axis <NUM> may be defined for the blower <NUM>. In some embodiments, as illustrated in <FIG> and <FIG>, both the inlet portion <NUM> and outlet portion <NUM> may extend along (such as linearly and coaxially along) the longitudinal axis <NUM>. In other embodiments, as illustrated in <FIG>, the outlet portion <NUM> may extend along (such as linearly and coaxially along) the longitudinal axis <NUM> while at least a portion of the inlet portion <NUM> extends in a direction other than linearly along the longitudinal axis <NUM>. For example, the inlet portion <NUM> may include a curvilinear portion <NUM> which extends along a curvilinear path relative to the longitudinal axis <NUM>. In some embodiments, the curvilinear portion <NUM> may connect to the outlet portion <NUM>, while in other embodiments, a linear portion <NUM> of the inlet portion <NUM> which extends along (such as linearly and coaxially along) the longitudinal axis <NUM> is disposed between and connects the curvilinear portion <NUM> and the outlet portion <NUM>.

In some embodiments, the curvilinear portion <NUM> may include a first portion <NUM> which curves in a first direction and a second portion <NUM> which curves in a second opposite direction. Accordingly, in these embodiments the curvilinear portion <NUM> may have an S-shape.

In some embodiments, as illustrated in <FIG> and <FIG>, a plane defined by the inlet end <NUM> is perpendicular to the longitudinal axis <NUM>. In other embodiments, as illustrated in <FIG>, a plane defined by the inlet end <NUM> is at an angle <NUM> to perpendicular to the longitudinal axis <NUM>. The angle <NUM> may, for example, be between <NUM> degrees and <NUM> degrees, such as between <NUM> degrees and <NUM> degrees, such as between <NUM> degrees and <NUM> degrees. In exemplary embodiments as illustrated, such inlet end <NUM> may for example face away from the handle <NUM>, and may face towards the ground when a user is holding the blower <NUM> in an operable position.

Referring now in particular to <FIG>, a blower <NUM> in accordance with the present disclosure may include an inlet muffler <NUM> which is provided at the inlet end <NUM>. Inlet muffler <NUM> may be connected to main body <NUM>, and airflow path <NUM> may be defined through the inlet muffler <NUM>. In an embodiment, the inlet muffler <NUM> can be detachably connected to the main body <NUM>. The inlet muffler <NUM> may be swappable between various designs having different performance characteristics and attributes.

Inlet muffler <NUM> may advantageously include a plurality of inlet ports <NUM>. Each inlet port <NUM> may be discrete from others of the plurality of inlet ports <NUM>. In some exemplary embodiments, the plurality of inlet ports <NUM> may generally be aligned parallel to each other, e.g., the plurality of inlet ports <NUM> may lie along a single plane. In other embodiments, one or more inlet ports <NUM> may be aligned in a non-parallel manner with respect to other inlet ports <NUM>. Each of the plurality of inlet ports <NUM> may include a peripheral surface <NUM> which defines a port aperture <NUM> through which the airflow path <NUM> is defined. Airflow path <NUM> may thus be defined through the plurality of inlet ports <NUM>.

The use of a plurality of inlet ports <NUM>, rather than a single inlet, advantageously allows for a significant reduction in the overall length of the muffler <NUM>, such as by two to three times the length. In exemplary embodiments, the plurality of inlet ports <NUM> may include, such as consist of, between four and ten inlet ports <NUM>, such as between five and nine inlet ports <NUM>, such as between six and eight inlet ports <NUM>, such as seven inlet ports <NUM>.

In one or more embodiments, at least one of the plurality of inlet ports <NUM> can define a polygonal cross-sectional shape. In the exemplary embodiment illustrated in <FIG>, each of the plurality of inlet ports <NUM> has a hexagonal cross-sectional shape. In exemplary embodiments, the plurality of inlet ports <NUM> may include a central inlet port 42C surrounded by a number of surrounding ports <NUM>, such as a layer of six surrounding ports <NUM>. In one or more embodiments, volumetric air flow through the inlet ports <NUM> may be generally equal between the different inlet ports <NUM>. In other embodiments, the inlet ports <NUM> may receive different amounts of volumetric air flow therethrough. For example, the central inlet port 42C may receive lower volumetric air flow rates as compared to each of the six surrounding ports <NUM>.

Referring to <FIG>, in another exemplary embodiment, the plurality of inlet ports <NUM> may have curvilinear cross-sectional shapes defined by the peripheral surfaces <NUM>. Curvilinear cross-sectional shapes can include circular cross sections (<FIG>), ovular cross sections (<FIG>), or other elongated, non-polygonal cross-sectional shapes. Ovular cross-sectional shapes can define aspect ratios [DMAX/DMIN], as measured by a maximum dimension of the shape, DMAX, relative to a minimum dimension of the shape, DMIN, of at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>. In an embodiment, the aspect ratio [DMAX/DMIN] can be no greater than <NUM>, such as no greater than <NUM>, such as no greater than <NUM>.

In an embodiment, the inlet muffler <NUM> can define a central inlet port 42C having one or more different attributes as compared to the surrounding inlet ports <NUM> (see, e.g., <FIG>). For instance, the central inlet port 42C can have a different size than the surrounding inlet ports <NUM>, a different shape than the surrounding inlet ports <NUM>, a different angular orientation than the surrounding inlet ports <NUM>, or any combination thereof.

In an embodiment, the surrounding inlet ports <NUM> may lie along a circular arc extending equidistant around a center point of the inlet muffler <NUM> (e.g., <FIG>). That is, each of the surrounding inlet ports <NUM> may be equidistant from the center point of the inlet muffler <NUM>. In another embodiment, the surrounding inlet ports <NUM> may lie along an ovular, or otherwise elongated, arc extending around the center point of the inlet muffler <NUM> (e.g., <FIG>). The non-circular arc of the surrounding inlet ports <NUM> may directionally alter airflow along the airflow path <NUM>, for example, causing greater air draw into the inlet muffler <NUM> from a desired location there along.

<FIG> illustrates yet another embodiment of an inlet muffler <NUM> including rectangular cross-sectional shaped inlet ports <NUM>. More particularly, <FIG> illustrates square inlet ports <NUM> arranged in a grid pattern. While illustrated with only five square inlet ports <NUM>, in other embodiments, the grid can include at least six inlet ports <NUM>, such as at least seven inlet ports <NUM>, such as at least eight inlet ports <NUM>, and so on. In an embodiment, the peripheral surfaces <NUM> of the polygonal (e.g., square) inlet ports <NUM> can define arcuate interfaces where the peripheral surfaces <NUM> join together. In another embodiment, the peripheral surfaces <NUM> can define linear junctions, e.g., <NUM>° interfaces as illustrated in <FIG>.

In an embodiment, the inlet muffler <NUM> can define an airflow ratio, <MAT>, as measured by a ratio of a cross-sectional area of the inlet muffler <NUM> through which airflow can pass unrestricted, AFP, relative to the total cross-sectional area of the inlet muffler <NUM>, AFT, no less than <NUM>, such as no less than <NUM>, such as no less than <NUM>, such as no less than <NUM>, such as no less than <NUM>, such as no less than <NUM>.

In an embodiment, the height of the peripheral surfaces <NUM> of adjacent inlet ports <NUM>, as measured parallel with the longitudinal axis <NUM>, can be different. For instance, the central inlet port 42C of <FIG> can define a first height, HC, different from a second height, HS, of one or more of the surrounding inlet ports <NUM>. In an embodiment, HC can be greater than HS. For instance, HC can be at least <NUM>% HS, such as at least <NUM>% HS, such as at least <NUM>% HS, such as at least <NUM>% HS, such as at least <NUM>% HS. In another embodiment, HC can be less than <NUM>% HS, such as less than <NUM>% HS, such as less than <NUM>% HS, such as less than <NUM>% HS, such as less than <NUM>% HS. In one or more embodiments, the height of the inlet ports <NUM> can gradually change, such as illustrated in <FIG>. In other embodiments, the inlet ports <NUM> can include a castellated trailing surface defined by non-gradual height changes.

Referring again to <FIG>, in one or more embodiments, the inlet muffler <NUM> can include one or more secondary inlet ports <NUM>. In an embodiment, the secondary inlet ports <NUM> may define openings disposed radially between the central inlet port 42C and the surrounding inlet ports <NUM>. The secondary inlet ports <NUM> may have different characteristics as compared to the central inlet port 42C, the surrounding inlet ports <NUM>, or both. For instance, the secondary inlet ports <NUM> may be smaller than the surrounding inlet ports <NUM>. The secondary inlet ports <NUM> may generate desirable air flow patterns within the blower <NUM>. By way of example, air flow paths through the secondary inlet ports <NUM> may be angularly offset from the inlet ports <NUM> and 42C. The angularly offset flow paths may enhance air mixing within the blower <NUM> and/or generate a pre-swirl of air entering the inlet muffler <NUM>.

In certain instances, at least one of the inlet ports <NUM> may be canted relative to the longitudinal axis <NUM> of the blower <NUM>. For example, <FIG> illustrates a cross-sectional view of a schematic of the inlet muffler <NUM>. In one or more embodiments peripheral surfaces 44A of the angled inlet ports 42A of the inlet muffler <NUM> can be canted relative to the longitudinal axis <NUM> of the blower <NUM>. Air drawn into the blower <NUM> through the inlet muffler <NUM> can travel along a modified air flow path <NUM> created by the angled inlet ports 42A. As a result, air passing through the inlet muffler <NUM> can be angularly offset by an angle, αA, as compared to air entering the same inlet muffler <NUM> with non-angled inlet ports <NUM>. In certain instances, the air flow path <NUM> can straighten slightly, i.e., conform slightly from the angle, αA, toward the longitudinal axis <NUM> of the blower <NUM>, after passing through the inlet muffler <NUM> as a result of negative pressure caused longitudinally downstream by rotor blades associated with the spinning motor.

In an embodiment, the degree of angular offset, αA, of the modified air flow path <NUM> may be determined at least in part by an angular displacement, αD, of the angled inlet ports 42A relative to the longitudinal axis <NUM>. In an embodiment, the angular displacement, αD, of the angled inlet ports 42A can be at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°. While illustrated with straight peripheral surfaces 44A, in another embodiment, the peripheral surface(s) 44A of at least one of the angled inlet ports 42A can be arcuate, polygonal, or include arcuate and linear portions, as viewed in cross section. Moreover, at least two of the peripheral surfaces 44A can define different angular displacements, αD, as compared to one another, thereby creating multiple unique modified air flow paths <NUM>.

In an embodiment, the angular displacement, αD, of the angled inlet ports 42A can be fixed. That is, the angular displacement of the angled inlet ports 42A can be set at a non-adjustable angle relative to the longitudinal axis <NUM>. In another embodiment, the angular displacement, αD, of the angled inlet ports 42A can be variable. For example, the blower <NUM> can include an operable interface (not illustrated) configured to permit an operator to selectively adjust the angular displacement, αD, of the angled inlet ports 42A. Using the operable interface, the operator can, for example, decrease the angular displacement, αD, of the angled inlet ports 42A or increase the angular displacement, αD, of the angled inlet ports 42A. The operable interface may be selectively lockable to maintain the angled inlet ports 42A at the desired angular displacement, αD.

Angled inlet ports 42A may be suitable for generating pre-swirl in the blower <NUM>. That is, air flow into the blower <NUM> through angled inlet ports 42A of the inlet muffler <NUM> may be angularly offset relative to the longitudinal axis <NUM>, creating rotational air patterns in the blower <NUM> prior to passing the motor <NUM> or rotor blades associated therewith. In an embodiment, the pre-swirl air flow condition can define the same direction of rotation through the blower <NUM> as caused by rotation of the downstream rotor blades. Use of a pre-swirl air flow condition may enhance noise reduction while maintaining performance of the blower <NUM> by reducing choppiness at the rotor blades.

Referring again to <FIG>, a damper material <NUM> may be provided on the peripheral surface <NUM> of each of the plurality of inlet ports <NUM>, such as generally an entire periphery of the peripheral surface <NUM> of each of the plurality of inlet ports <NUM>. The damper material <NUM> may further define the port aperture <NUM> therethrough, as shown. Accordingly, damper material <NUM> may further define the airflow path <NUM>. Damper material <NUM> may be formed from a suitable damping material, such as in exemplary embodiments a foam or a fiber-based composite or other material, such as a glass-fiber or natural-fiber (such as jute) based composite or other material. In exemplary embodiments, the damping material may be an open cell material, such as an open cell foam. For example, damper material <NUM> may be formed from a polyurethane foam, such as in exemplary embodiments an open cell polyurethane foam. In exemplary embodiments, each damper material <NUM> may have a thickness <NUM> of between <NUM> millimeters and <NUM> millimeters, such as between <NUM> millimeters and <NUM> millimeters, such as <NUM> millimeters.

<FIG> illustrates an exemplary framework <NUM> disposed within the damper material <NUM>. As illustrated in <FIG>, the framework <NUM> can generally include a body <NUM> extending between a first axial end <NUM> and a second axial end <NUM>. At least one of the first and second axial ends <NUM> and <NUM> can define a tapered profile, e.g., a flared opening, to facilitate airflow therethrough. The framework <NUM> can include one or more openings <NUM>, such as a plurality of openings <NUM>. The opening(s) <NUM> can be disposed along the body <NUM> and expose the damper material <NUM> to air passing through the air inlet port <NUM>. In an embodiment, the body <NUM> can include at least ten openings <NUM>, such as at least twenty openings <NUM>, such as at least fifty openings <NUM>. In an embodiment, the openings <NUM> can extend in one or more rows and/or one or more columns along the body <NUM>. In an embodiment, the openings <NUM> can define a damper material exposure [AO/SAB], as measured by an area, AO, of all of the openings <NUM> of the framework <NUM> combined relative to a surface area, SAB, of the body <NUM>, of at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>. A relatively high damper material exposure may reduce noise from the blower <NUM>, while a relatively low damper material exposure may lengthen effective operational lifespan of the damper material <NUM>. In an embodiment, the damper material exposure is in a range between <NUM> and <NUM>, such as in a range between <NUM> and <NUM>.

In an embodiment, the framework <NUM> can further include retaining structures <NUM> configured to engage with the damper material <NUM>. The retaining structures <NUM> can include, for example, clips, threaded fasteners, non-threaded fasteners, button fasteners, hooks, one or more mollies, hook and loop engagement, or other known attachment protocol. In an embodiment, the framework <NUM> can be removably attached to the damper material <NUM>. In such a manner, the operator can selectively change the damper material <NUM>, e.g., if the damper material <NUM> fouls or becomes contaminated during use.

In certain instances, the outer surface of the body <NUM> can define a shape generally similar to an inner shape of the damper material <NUM>. In the illustrated embodiment, the framework <NUM> defines a generally hexagonal shape. In another embodiment, the framework <NUM> can define a curvilinear shape or have a shape corresponding to a different polygonal arrangement. In an embodiment, the damper material <NUM> can have a split <NUM> to permit installation thereof over the framework <NUM>. For example, referring to <FIG>, the split <NUM> can extend axially between the first and second axial ends <NUM> and <NUM>. During installation, the damper material <NUM> can be spread such that the framework <NUM> passes through the split <NUM>. After installation, the split <NUM> can be connected, e.g., circumferential ends thereof can be fixed together, or left open. In a non-illustrated embodiment, the framework <NUM> can be installed within the damper material <NUM> by axially translating the framework <NUM> through an opening of the damper material <NUM>.

Referring to <FIG>, in one or more embodiments the inlet muffler <NUM> can define one or more auxiliary openings <NUM> passing through a side surface <NUM> of the inlet muffler <NUM>. In a non-illustrated embodiment, at least one of the openings <NUM> can be part of the main body <NUM>. By way of example, the inlet muffler <NUM> can include at least one opening <NUM>, such as at least two openings <NUM>, such as at least five openings <NUM>, such as at least ten openings <NUM>. In an embodiment, the openings <NUM> can be equidistantly spaced apart from another around a circumference of the inlet muffler <NUM>. In another embodiment, the openings <NUM> can be stacked closer together at one location and spaced further apart at another location. For instance, the openings <NUM> may be stacked closer together at a top side of the blower <NUM> and spaced further apart from one another at a bottom side of the blower <NUM>. The openings <NUM> may define air flow paths generally normal to the air flow path <NUM> previously described in the blower <NUM>. In normal use, the openings <NUM> may work together with air inlets <NUM> to allow air into the inlet portion <NUM> of the blower. The openings <NUM> may advantageously permit air into the inlet portion <NUM> when one or more inlet ports <NUM> become restricted, e.g., with leaves or other debris stuck on the inlet muffler <NUM>. Traditionally, such restrictions can increase motor noise, however, inclusion of openings <NUM> may allow the motor to operate at a more desirable power level even upon occurrence of restrictions along the inlet muffler <NUM>.

In one or more embodiments, the one or more openings <NUM> can all have a same shape, size, or both. In other embodiments, at least two of the openings <NUM> can be different from one another, e.g., have different sizes, shapes, or both. By way of example, at least one of the openings <NUM> can have an arcuate shape, e.g., circular or ovular shape, or a polygonal shape, e.g., a rectangular or pentagonal shape.

In a non-illustrated embodiment, the blower <NUM> can further include an adjustable interface configured to selectably restrict air flow passage through at least one of the one or more openings <NUM>. The adjustable interface can include, for example, a rotatable or translatable sleeve disposed around the inlet muffler <NUM> and configured to selectively restrict air flow through the openings <NUM>. The operator can adjust the angular or linear displacement of the sleeve to selectively adjust air flow through the openings <NUM>. In certain non-limiting embodiments, the sleeve may be part of the inlet muffler <NUM>.

Inlet muffler <NUM> advantageously provides significant noise reduction for blowers <NUM> in accordance with the present disclosure. Such noise reduction is advantageously provided while maintaining the performance of the blower <NUM>. Further, such inlet mufflers <NUM> are relatively small in length, and use relatively thin damper materials <NUM>, while providing such advantageous noise reduction.

Referring now to <FIG> and <FIG>, various components may be disposed within the main body <NUM> which advantageously provide noise reduction in blowers <NUM> in accordance with the present disclosure. For example, a fan assembly <NUM> is disposed within the main body <NUM>, such as in the inlet portion <NUM> thereof. Fan assembly <NUM> includes an axial fan <NUM> which includes a hub <NUM> and a plurality of rotor blades <NUM> extending radially outwardly from the hub <NUM>.

<FIG> illustrates a front view of the axial fan <NUM> as seen looking from an upstream position in accordance with one or more embodiments herein. As illustrated, the rotor blades <NUM> extend radially outward from the hub <NUM>. During normal operations, the hub <NUM> is configured to rotate in a direction indicated by arrow <NUM>. In this regard, each rotor blade <NUM> can define a leading edge <NUM> and a trailing edge <NUM> with respect to the angle of rotation. In an embodiment, at least a portion of at least one of the leading and trailing edges <NUM> and <NUM> can have a linear, i.e., straight, profile, as viewed along the longitudinal axis <NUM> of the blower <NUM>. In another embodiment, at least a portion of at least one of the leading and trailing edges <NUM> and <NUM> can have a curved profile. In the illustrated embodiment, the leading and trailing edges <NUM> and <NUM> are both forward swept. That is, the leading and trailing edges <NUM> and <NUM> are angularly offset from lines <NUM> extending radially from a center point <NUM> of the axial fan <NUM>. In another embodiment, only one of the leading and trailing edges <NUM> or <NUM> of at least one of the rotor blades <NUM> is forward swept. In yet a further embodiment, neither the leading or trailing edges <NUM> and <NUM> of at least one of the rotor blades <NUM> is forward swept. For example, at least one of the leading or trailing edges <NUM> and <NUM> of at least one of the rotor blades <NUM> may be backward swept or lie generally along the line <NUM> extending radially from the center point <NUM>.

The rotor blades <NUM> may be angled relative to the air flow path <NUM> to generate positive pressure on a downstream side of the axial fan <NUM> and corresponding negative pressure on an upstream side thereof. Referring to <FIG>, the rotor blades <NUM> can be angled with respect to the longitudinal axis <NUM> of the blower <NUM>. For instance, one of the rotor blades <NUM> can define a cross-sectional shape with a best fit line <NUM> angularly offset from the longitudinal axis <NUM> of the blower by an angle of attack, AOA. The angle of attack of the rotor blades <NUM> may specify the positive and negative pressures generated by the axial fan <NUM> at operating speeds. By way of example, the angle of attack of at least one of the rotor blades <NUM> may be between <NUM>° and <NUM>°, such as between <NUM>° and <NUM>°.

In an embodiment, at least two of the rotor blades <NUM> can define different angles of attack. For instance, a first rotor blade 56A may define a first angle of attack, AOA<NUM>, and a second rotor blade 56B may define a second angle of attack, AOA<NUM>, different than AOA<NUM>. By way of example, AOA<NUM> may be greater than AOA<NUM>. For example, AOA<NUM> may be <NUM> AOA<NUM>, such as <NUM> AOA<NUM>, such as <NUM> AOA<NUM>, such as <NUM> AOA<NUM>, such as <NUM> AOA<NUM>, such as <NUM> AOA<NUM>, such as <NUM> AOA<NUM>. In an embodiment, the angle of attack of adjacent rotor blades <NUM> may be different from one another. For instance, the rotor blades <NUM> may have alternating angles of attack, progressively staggered angles of attack, random angles of attack, or any other possible variation. Without wishing to be bound to a particular theory, it is believed that modifying the angle of attack of at least one of the rotor blades <NUM> with respect to other rotor blades <NUM> on the axial fan <NUM> may enhance noise reduction without sacrificing power of the blower <NUM>.

<FIG> illustrates an embodiment of a rotor blade <NUM> including serrations <NUM> disposed on edges <NUM> of the rotor blades <NUM>. In one or more embodiments, the serrations <NUM> can be disposed on leading edge(s) <NUM> of at least one of the rotor blades <NUM>. In one or more embodiments, the serrations <NUM> can be disposed on radially outer edge(s) <NUM> of at least one of the rotor blades <NUM>. In one or more embodiments, the serrations <NUM> can be disposed on trailing edge(s) <NUM> of at least one of the rotor blades <NUM>. In an embodiment, the serrations <NUM> can be disposed on any combination of leading, radially outer, and trailing edges <NUM>, <NUM>, and <NUM>.

In an embodiment, the serrations <NUM> can all define a same, or generally similar, shape and/or depth into the rotor blade <NUM>. In another embodiment, at least two serrations <NUM> can have different characteristics as compared to one another, e.g., different shapes and/or depths as compared to one another. For example, the serrations on the leading edge <NUM> of a first rotor blade 1710a can be different than the serrations on the leading edge <NUM> of a second rotor blade 1710b. In another exemplary embodiment, the serrations on the leading edge <NUM> of the first rotor blade 1710a can be different from the serrations of the radially outer edge <NUM> of the first rotor blade 1710a.

The serrations <NUM> can be shaped to reduce noise of the axial fan <NUM> without sacrificing power of the blower <NUM>. The serrations <NUM> can include curvilinear portions, polygonal portions, or any combination thereof. In certain instances, the serrations <NUM> can have beveled, or multi-beveled, side surfaces that taper between axially opposite ends of the axial fan <NUM>. In other instances, the serrations <NUM> can have straight or otherwise non-beveled side surfaces. In an embodiment, the serrations <NUM> can have rounded corners. In other embodiments, the serrations <NUM> can have angled corners.

Referring again to <FIG>, the fan assembly <NUM> further includes a motor <NUM> which is rotatably connected to the axial fan <NUM> and may cause the axial fan <NUM> to rotate due to operation thereof. For example, a shaft <NUM> may rotatably couple the motor <NUM> to the axial fan <NUM>, such as to the hub <NUM> thereof. Rotation of the motor <NUM> may cause rotation of the shaft <NUM> and thus cause rotation of the axial fan <NUM>.

Shaft <NUM> and axial fan <NUM> may be positioned on an upstream side of the motor <NUM> along the airflow path <NUM>. Further, in some embodiments, a secondary fan <NUM> (which may be an axial fan having a hub and a plurality of rotor blades extending radially therefrom) and secondary shaft <NUM> (which may be integral with the shaft <NUM>) may be positioned on a downstream side of the motor <NUM>. Motor <NUM> may be operably coupled to the secondary fan <NUM> and may cause the secondary fan <NUM> to rotate due to operation thereof. Secondary shaft <NUM> may rotatably couple the motor <NUM> to the secondary fan <NUM>, such as to a hub thereof. Rotation of the motor <NUM> may cause rotation of the secondary shaft <NUM> and thus cause rotation of the secondary fan <NUM>. The secondary fan <NUM> may include any one or more of the features previously described with respect to the axial fan <NUM>.

In exemplary embodiments, the motor <NUM> may be a brushless DC motor. Further, in exemplary embodiments, the motor <NUM> may be an outrunner type DC motor. Such outrunner type motors may be particularly advantageous due to their ability to provide relatively higher torque for a given motor diameter as compared to inrunner type motors.

Fan assembly <NUM> may further include a motor housing <NUM> which may generally surround and house the motor <NUM>. Motor housing <NUM> may further surround and house the secondary shaft <NUM> and secondary fan <NUM>. Shaft <NUM> may extend from the motor housing <NUM>, and fan <NUM> may be exterior to the motor housing <NUM>. Accordingly, motor housing <NUM> may be downstream of the fan <NUM> along the airflow path <NUM>. In exemplary embodiments, at least a portion of the motor housing <NUM> (such as a downstream portion) is generally cone-shaped and thus tapers in diameter along the airflow path <NUM>.

A plurality of stator vanes <NUM> may extend, such as generally radially, from the motor housing <NUM>. Stator vanes <NUM> may thus be downstream of the fan <NUM> along the airflow path <NUM>. In exemplary embodiments, the plurality of stator vanes <NUM> may include, such as consist of, between four and twelve stator vanes <NUM>, such as between six and eleven stator vanes <NUM>, such as between eight and ten stator vanes <NUM>, such as nine stator vanes <NUM>. The use of a relatively higher number of stator vanes <NUM> advantageously increases the initial resonant frequency associated with the stator vanes <NUM>, thus providing a resonant frequency which can be more easily muffled using noise reduction features as discussed herein.

In exemplary embodiments, the downstream or trailing edges <NUM> of the stator vanes <NUM> may include noise reduction features <NUM>. Such noise reduction features <NUM> may be structures mounted to the trailing edges <NUM> or shapes defined in the trailing edges <NUM>, as shown. For example, in exemplary embodiments, such noise reduction features <NUM> are chevron shapes defined in the trailing edges <NUM>. Noise reduction features <NUM> in accordance with the present disclosure advantageously provide further noise reduction for blowers <NUM> in accordance with the present disclosure.

Fan assembly <NUM> further includes an outer housing <NUM>. Outer housing <NUM> surrounds the fan <NUM> and motor <NUM>, and may further surround the secondary fan <NUM>. Outer housing <NUM> may further surround stator vanes <NUM>, and stator vanes <NUM> may extend between and be connected to motor housing <NUM> and outer housing <NUM>. Outer housing <NUM> may further surround at least a portion of the motor housing <NUM>, such as an upstream portion thereof relative to airflow path <NUM>. In some embodiments, a downstream portion of the motor housing <NUM> relative to the airflow path <NUM> may extend from the outer housing <NUM>.

In some embodiments, outer housing <NUM> may include a bellmouth inlet <NUM> on an upstream end thereof in the airflow path <NUM>. Bellmouth inlet <NUM> may facilitate the flow of air into and through the fan assembly <NUM>.

In exemplary embodiments, a plurality of bushings <NUM> may be provided. Each bushing <NUM> may be disposed in contact between the outer housing <NUM> and the main body <NUM> (such as the inlet potion <NUM> thereof). Accordingly, each bushing <NUM> may be radially outward of the outer housing <NUM>. Bushings <NUM> may in exemplary embodiments be formed from a suitable resilient material such as a rubber. Bushings <NUM> may support the outer housing <NUM> within and relative to the main body <NUM> and may advantageously reduce the noise associated with the fan assembly <NUM> due, for example, to vibration of the outer housing <NUM> and other components of the fan assembly <NUM> during operation of the blower <NUM>.

<FIG> illustrates an embodiment of the blower <NUM> including dampening elements <NUM> disposed between the outer housing <NUM> and the bellmouth (not illustrated). The dampening elements <NUM> may be disposed in slots <NUM> of the outer housing <NUM>. The dampening elements <NUM> may comprise foam, such as closed cell foam. The dampening elements <NUM> may be formed of a material having a higher density than the damper material <NUM> previously described. In an embodiment, the dampening elements <NUM> may reduce vibrational noise along the outer housing <NUM> thereby mitigating audible noise from the blower <NUM>.

Referring now to <FIG>, in one or more embodiments, the blower <NUM> can further include a stator <NUM> upstream of the axial fan <NUM>. The stator <NUM> may form a pre-swirl of air within the inlet portion <NUM> ahead of the axial fan <NUM>. Air entering through the inlet muffler <NUM> may pass through the stator <NUM> where the air becomes rotationally swirled as it enters an area associated with the rotor blades <NUM> of the axial fan <NUM>. In an embodiment, the stator <NUM> may include a plurality of vanes <NUM> configured to rotationally swirl the air in a pre-swirled path. The rotational pre-swirl may permit the axial fan <NUM> to operable at a lower noise level while producing the same output power. In an embodiment, the stator <NUM> can be attached to, or part of, the bellmouth inlet <NUM>. By way of example, the stator <NUM> can be snap fit, fastened, or otherwise connected to the bellmouth inlet <NUM> or integrally formed therewith. The stator <NUM> may generally be disposed upstream of the axial fan <NUM> and downstream of the inlet muffler <NUM> and condition the airflow for improved noise performance.

In an embodiment, the bellmouth <NUM> can define one or more surface features <NUM> extending into the air flow path <NUM>. The surface features <NUM> can include, for example, bumps, ridges, protrusions, vanes, dimples, posts, grooves, surface roughness, textures, three dimensional indicia, funnels, castellations, undulations, other surface features, or any combination thereof. The surface features <NUM> may enhance noise reduction, for example, by breaking up local noise generating areas and enhancing air flow through the blower <NUM>.

Referring now to <FIG>, blowers <NUM> in accordance with the present disclosure further include damper liners <NUM>. A damper liner <NUM> is disposed within the main body <NUM>, such as relatively proximate the outlet end <NUM> and relatively distal from the inlet end <NUM>. Damper liner <NUM> is disposed downstream of the outer housing <NUM> along the airflow path <NUM>. In some embodiments, damper liner <NUM> may contact a downstream end of the outer housing <NUM>. In some embodiments, a downstream portion of the motor housing <NUM> may be surrounded by the damper liner <NUM>. Damper liner <NUM> may, for example, be disposed entirely within the outlet portion <NUM> or may extend between and within both the inlet portion <NUM> and outlet portion <NUM>.

Damper liner <NUM> may have a generally cylindrical shape, and may contact the main body <NUM>. Accordingly, damper liner <NUM> may further define the airflow path <NUM>. Damper liner <NUM> may be formed from a suitable damping material, such as in exemplary embodiments a foam or a fiber-based composite or other material, such as a glass-fiber or natural-fiber (such as jute) based composite or other material. In exemplary embodiments, the damping material may be an open cell material, such as an open cell foam. For example, damper liner <NUM> may be formed from a polyurethane foam, such as in exemplary embodiments an open cell polyurethane foam. In exemplary embodiments, the damper liner <NUM> and damper material <NUM> are formed from the same damping material.

In exemplary embodiments, the damper liner <NUM> may have a thickness <NUM> of between <NUM> millimeters and <NUM> millimeters, such as between <NUM> millimeters and <NUM> millimeters, such as <NUM> millimeters.

According to the invention, at least one air gap <NUM>, such as a plurality of air gaps <NUM>, is defined between the damper liner <NUM> and the main body <NUM>. Each air gap <NUM> may have a depth <NUM> (along a radial direction) of between <NUM> millimeters and <NUM> millimeters, such as between <NUM> millimeters and <NUM> millimeters, such as between <NUM> millimeters and <NUM> millimeters, such as <NUM> millimeters. Each air gap <NUM> may extend circumferentially between the damper liner <NUM> and main body <NUM>, and in exemplary embodiments each air gap <NUM> may be an annular air gap <NUM> which extends through an entire circumference. The use of air gaps <NUM> in accordance with the present disclosure advantageously provides further noise reduction and reduces the thickness <NUM> required for damper liner <NUM> to be effective in providing suitable noise reduction.

Damper liner <NUM> advantageously provides significant noise reduction for blowers <NUM> in accordance with the present disclosure. Such noise reduction is advantageously provided while maintaining the performance of the blower <NUM>. Further, damper liner <NUM> can be relatively thin while providing such advantageous noise reduction.

<FIG> illustrates an enlarged view of an embodiment of the blower <NUM> including a handle <NUM> rotatably coupled to the main body <NUM> of the blower <NUM>. The handle <NUM> may be rotatable along a pivot axis <NUM> in directions 140A and/or 140B. In an embodiment, the handle <NUM> can be rotatable along the pivot axis <NUM> by at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°, such as at least <NUM>°. In another embodiment, the handle <NUM> can be rotatable along the pivot axis <NUM> no greater than <NUM>°, such as no greater than <NUM>°, such as no greater than <NUM>°. Through rotatably adjusting the orientation of the handle <NUM> along the pivot axis <NUM>, the operator may better align the handle <NUM> for ergonomic use at multiple operating orientations and positions. In one or more embodiments, the blower <NUM> can define preset rotatable positions, e.g., a discrete number of rotatable stop points along the pivot axis <NUM>, where the handle <NUM> can be adjusted between. In other embodiments, the handle <NUM> can be infinitely adjustable, i.e., the handle <NUM> can be stopped at any suitable rotational orientation within a maximum rotatable path of the handle <NUM>.

In an embodiment, the handle <NUM> can be selectively secured at a desired angular orientation via a selectable locking mechanism, such as a knob <NUM>, configured to temporarily secure the handle <NUM> at the desired angular orientation. The knob <NUM> can include, for example, a winged nut connected to, or integrally formed with, an elongated member extending through the handle <NUM>. Tightening the knob <NUM> can selectively maintain the handle <NUM> in the desired angular orientation. In certain instances, the knob <NUM> can include indicia indicating a direction for tightening and loosening. The knob <NUM> can include a grippable interface, such as one or more projecting surface(s), pads, or other elements to prevent the operator from slipping during tightening or loosening. In an embodiment, the knob <NUM>, or one or more components associated therewith, can create a tactile indication to the operator when the knob <NUM> is sufficiently tightened so as to maintain the handle <NUM> in the desired angular orientation.

In other embodiments, the selectable locking mechanism can include a button fastener, a bayonet-type connection, a latch or lever, a selectable bearing or gearing system, one or more pins extendable into the handle <NUM>, another suitable mechanism known in the art, or any combination thereof. The selectable locking mechanism may include one or more locking features to maintain the locking mechanism in the locked configuration, i.e., the handle <NUM> is selectively secured at the desired angular orientation.

In certain instances, the blower <NUM> may be usable with various sized/shaped batteries <NUM> (<FIG>) receivable in the battery mount <NUM>. For larger batteries <NUM>, it may be desirable to rotate the handle <NUM> in the direction of arrow 140A to increase the space between the battery <NUM> and the operator's hand. For smaller batteries <NUM>, the operator may rotate the handle <NUM> forward in the direction of arrow 140B. In an embodiment, the different sized batteries <NUM> can include instruction as to the correct angular orientation of the handle <NUM> for operating with the battery <NUM>.

In a non-illustrated embodiment, the handle <NUM> may be rotatable along a different pivot axis than pivot axis <NUM>. For example, the handle <NUM> may be rotatable along a pivot axis <NUM>. Pivot axis <NUM> may permit the operator to rotate the handle <NUM> along a plane parallel, or generally parallel, with a length of the blower <NUM>.

Referring to <FIG>, the blower <NUM> may include a leaf scraper <NUM> disposed at or adjacent to the outlet end <NUM>. The leaf scraper <NUM> may extend from the outlet portion <NUM> of the blower <NUM> and provide a surface against which an operator can contact leaves and surface debris which may be adhered to the surface, requiring mechanical contact to free. In an embodiment, the leaf scraper <NUM> may include a generally planar lip <NUM>. In a particular embodiment, the lip <NUM> may be formed from a relatively rigid material, such as a rigid plastic, metal, or alloy. In another particular embodiment, the lip <NUM> may be formed from a relatively pliable material, such as a rubber or soft plastic. As used herein, the terms "rigid" and "pliable" are used with respect to one another with rigid materials generally holding their shape under application of operational biasing pressure and pliable materials deforming under application of operational biasing pressure. In certain instances, rigid lip <NUM> may be suitable for applications where the operator wants to scrape an adhered leaf from the ground. In other instances, a pliable lip <NUM> may be suitable for applications where the operator wants to access a crevice or crack that the rigid lip <NUM> cannot reach. In an embodiment, the leaf scraper <NUM> may be removably attached to the blower <NUM> such that the operator can swap lips <NUM> for particular operations. In other embodiments, the leaf scraper <NUM> may be adjustable relative to the outlet portion <NUM>, e.g., rotatable, such that the operator can adjust between two different lips <NUM> without detaching either lip <NUM>. In yet another embodiment, the leaf scraper <NUM> can include rigid portions and pliable portions fixedly coupled to the blower <NUM>. The operator can select between the rigid and pliable lips <NUM> by rotating the blower <NUM> accordingly. In an embodiment, the leaf scraper <NUM> may prevent the outlet end <NUM> from contacting the ground, e.g., wet leaves, which might foul the outlet portion <NUM>.

<FIG> includes a schematic of an exemplary noise cancelling system <NUM> that may be utilized with the blower <NUM>. Much of the noise generated by equipment, such as blowers, occurs within a known range of audible frequencies formed of relatively known tonal signatures. The noise in blower <NUM> may be associated with the rotor blades <NUM>, the motor <NUM>, and other components creating drag and air pressure variations within the blower <NUM>. To mitigate and further reduce the noise of the blower <NUM>, the noise cancelling system <NUM> may include a microphone <NUM> and a sound source <NUM>, such as a speaker. The noise cancelling system <NUM> may further include a controller <NUM> configured to control the sound emitted from the sound source <NUM> in response to the perceived noise received by microphone <NUM>.

In an embodiment, the microphone <NUM> includes a sensitive audio element configured to sense sound and generate a representative electrical signal thereof. The microphone <NUM> may be located anywhere on the blower <NUM>, but in a particular embodiment is disposed near the axial fan <NUM> since a majority of the noise of the blower <NUM> is created by the axial fan <NUM> and elements associated with the motor <NUM>.

The controller <NUM> can be configured to receive the representative electrical signal of the noise from the microphone <NUM>. Based on this signal, the controller <NUM> can generate a second electrical signal indicative of a noise-cancelling signal. This operation may be performed in accordance with a number of well-known audio techniques. In a particular embodiment, the second electrical signal can be determined, for example, using adaptive finite impulse response filters.

In an embodiment, the sound source <NUM> may be disposed near the inlet muffler <NUM>, such as along or adjacent to an inner surface of the inlet muffler <NUM>. The sound source <NUM> may be configured to generate sound relating to the audible noise-cancelling signal to mitigate the noise created by the blower <NUM>. For example, the sound source <NUM> may generate an out of phase signal, e.g., a signal <NUM>° out of phase with the noise detected by the microphone <NUM>. The noise-cancelling signal may emanate from the blower <NUM> and mitigate the noise level detected by the operator and those nearby.

If further sound dampening is desired, the noise cancelling system <NUM> may further include an error sensor <NUM>, such as a secondary microphone, configured to detect sound and generate a third electrical signal representing the sound detected by the error sensor <NUM>. The third electrical signal can communicate with the controller <NUM> to further dampen the noise generated by the blower <NUM>.

In an embodiment, the blower <NUM> can define an operational power to dampening loss ratio <MAT> of at least <NUM>, where dBM is a muffled sound intensity of the blower <NUM> when equipped with an inlet muffler <NUM>, where dBU is a non-muffled sound intensity of the blower <NUM> when not equipped with the inlet muffler <NUM>, where PM is a maximum muffled operational power capacity of the blower <NUM> when equipped with the inlet muffler <NUM>, and where PU is a non-muffled operational power capacity of the blower <NUM> when not equipped with the inlet muffler <NUM>. In a more particular embodiment, the operational power to dampening loss ratio can be at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>.

Claim 1:
A blower (<NUM>), comprising:
a main body (<NUM>) defining an airflow path (<NUM>) therethrough, the main body (<NUM>) extending between and defining an inlet end (<NUM>) and an outlet end (<NUM>);
a fan assembly (<NUM>) disposed within the main body (<NUM>), the fan assembly (<NUM>) comprising an axial fan (<NUM>), a motor (<NUM>) rotatably connected to the fan (<NUM>), and an outer housing (<NUM>) surrounding the fan (<NUM>) and the motor (<NUM>); and
a damper liner (<NUM>), the damper liner (<NUM>) disposed within the main body (<NUM>) downstream of the outer housing (<NUM>) along the airflow path (<NUM>), characterized in that at least one air gap (<NUM>) is defined between the damper liner (<NUM>) and the main body (<NUM>).