Impeller blade with uneven spacing

Abstract

An impeller assembly configured to produce low noise is provided. In one embodiment, an impeller assembly is provided having a hollow cylindrical hub body with a sleeve extending therethrough. The sleeve is configured to receive a driveshaft of a motor to couple the impeller assembly to the motor. The impeller assembly includes a plurality of impeller blades extending radially outward therefrom. Each blade of the plurality of impeller blades is unevenly distributed around a circumference of the hub body.

Description

FIELD

The present application generally relates to impellers with unevenly-spaced blades for reducing noise.

BACKGROUND

Hair care appliances are devices used for the drying and styling of hair. Hair care appliances can include a variety of components, including impellers and motors. In operation, the impellers and motors work together to propel air and liquid through a flow path. Impellers generally include multiple blades which can be arranged in close proximity to the motor.

The impeller in a hair care appliance is often the source of significant noise, which can cause dizziness, headache and even insomnia to be felt after long-term use. The noise from the impeller can be caused by repeated outflow of fluid from individual blades (sound noise/narrow band noise) and turbulent passage of fluid over the blades (wide frequency band/broadband noise).

SUMMARY

In general, low-noise impellers are provided for use in a hair care devices. In one embodiment, an impeller assembly includes a generally cylindrical hollow hub body and a sleeve extending through the hub body. The sleeve can include a central bore therethrough configured to receive a driveshaft for coupling the impeller assembly to a motor. The impeller assembly can also include a plurality of vanes extending between the sleeve and the hub body, and a plurality of impeller blades extending radially outward from the hub body and being unevenly distributed around a circumference of the hub body.

In one aspect, each impeller blade of the plurality of impeller blades can be angled relative to a longitudinal axis of the hub body.

In another aspect, the plurality of impeller blades can include an uneven number of impeller blades.

In another aspect, each blade of the plurality of impeller blades can include an outer rim having a first vertex and a second vertex. A first distance between the first vertex of each impeller blade and a corresponding first vertex of a consecutive impeller blade in the clockwise direction can differ from a second distance between the first vertex of each impeller blade and a corresponding first vertex of a consecutive impeller blade in the counterclockwise direction.

In another aspect, a center of mass of the impeller assembly can be positioned along a longitudinal axis of the hub body.

In another aspect, rotation of the hub body can be configured to cause each of the plurality of impeller blades to create a pressure wave, and at least two of plurality of impeller blades can have pressure waves that differ from one.

In a further aspect, the impeller assembly can include a cylindrical covering disposed around the plurality of impeller blades. The cylindrical covering can include a plurality of diffusing apertures.

In another embodiment, an impeller assembly is provided and can include a hub body including an inner surface and an outer surface, and the inner surface can include a recess. The impeller assembly can further include a sleeve extending through a center of the hub body, and the sleeve can be configured to receive a driveshaft to physically couple the impeller assembly to a motor. The impeller assembly can further include a plurality of vanes extending from the sleeve to the inner surface. Additionally, the impeller assembly can include a plurality of impeller blades extending radially outward from the outer surface and spaced around a circumference of the outer surface. Each blade of the plurality of impeller blades can include an outer edge having a first vertex and a second vertex, and a first distance between the first vertex of each blade and a corresponding first vertex of an immediately adjacent blade in the clockwise direction that can differ from a second distance between the first vertex of each blade and a corresponding first vertex of an immediately adjacent blade in the counterclockwise direction.

In one aspect, each of the plurality of impeller blades of the impeller assembly can be angled related to a longitudinal axis of the sleeve.

In another aspect, a center of mass of the impeller assembly can be positioned along a longitudinal axis of the hub body.

In another aspect, rotation of the hub body can be configured to cause each of the plurality of impeller blades to create a pressure wave, and at least two of plurality of impeller blades can have pressure waves that differ from one.

In another aspect, rotation of the hub body can be configured to cause the plurality of impeller blades to produce a blade passage frequency, and the blade passage frequency can be configured to be at least 10% less than a blade passage frequency of a similar impeller assembly with evenly distributed blades.

In an additional aspect, the plurality of impeller blades can comprise a number of impeller blades having uneven spacing.

In another aspect, the impeller assembly can further comprise a cylindrical covering disposed around the plurality of impeller blades.

In another aspect, the cylindrical covering can include a plurality of diffusing apertures.

In another aspect, each of the plurality of vanes can be spaced equidistant from each other around the sleeve.

DESCRIPTION OF DRAWINGS

These and other features will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side view of a motor and impeller assembly;

FIG. 2 is a rear perspective view of the motor and impeller assembly of FIG. 1;

FIG. 3 is an isolated side perspective view of the impeller assembly of FIG. 2;

FIG. 4 is an isolated front perspective view of the impeller assembly of FIG. 3;

FIG. 5 is an isolated rear view of the impeller assembly of FIG. 3;

FIG. 6 is an isolated rear view of the impeller assembly of FIG. 3 including angle measurements;

FIG. 7 is a side perspective view of the motor and impeller assembly of FIG. 2 showing a casing disposed therearound;

FIG. 8 is a front perspective view of the motor, impeller assembly, and casing of FIG. 7, showing diffusion apertures;

FIG. 9 is a perspective view of one exemplary embodiment of a hair care appliance;

FIG. 10 is a side cross-sectional view of the hair care appliance of FIG. 9 including a handle and a body, taken along a fluid flow path line 1-1 of FIG. 9, and including the motor and impeller assembly of FIG. 1;

FIG. 11 is a chart depicting the interference function normalized to the number of blades for various impeller blades with different blade spacings;

FIG. 12 is a chart depicting the interference function normalized to the number of blades for an evenly spaced impeller and an unevenly spaced impeller;

FIG. 13 is a chart depicting the time domain pressure waveform approximated as a sawtooth wave for an evenly spaced impeller and an unevenly spaced impeller;

FIG. 14 is a chart depicting the amplitudes at different frequencies for an evenly spaced impeller and an unevenly spaced impeller; and

FIG. 15 is a perspective view of an exemplary embodiment of an impeller having a plurality of blades arranged in a pseudo random, unevenly spaced arrangement.

It is noted that the drawings are not necessarily to scale. The drawings are intended to depict only typical aspects of the subject matter disclosed herein, and therefore should not be considered as limiting the scope of the disclosure.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

Rotating machinery like motors and pumps often generate unwanted noise in the form of broadband and tonal noise. Tonal noise, that is, noise at a discrete frequency (ie. 1000 Hz), is often caused by the individual components of the rotating machinery. In the case of a motor for a hair care appliance, components which cause tonal noise include the impeller, motor poles, rotor slots, etc., as each member generates a pressure wave at a given point during its rotation. This pressure wave manifests itself as an audible sound to the consumer and can be quite annoying. For example, if a motor is spinning at 30,000 RPM (or, 500 RPS) with a 15-blade impeller, then one can imagine 15 blades passing by a given point 500 times per second. This results in an acoustic pressure wave at precisely 15*500=7500 Hz.

In consumer appliances, it can be advantageous to optimize the sound emanated from the product in a way that is appealing to the consumer. One quality of sound which is generally linked to poor consumer perception is the “tonality” of a sound. This can be measured using several metrics such as the “Tone-to-Noise Ratio” or “Prominence Ratio”. In general, the more prominent a discrete tone is above the broadband noise floor of a sound source, the more it stands out to the consumer. In the case of a motor for a hair care appliance, the tonal source caused by the passing of the motor's impeller blades, called the “Blade Pass Frequency” is a large source of consumer dissatisfaction. An improved impeller design should reduce the magnitude of this tone relative to the noise floor, in order to reduce the product's tonality.

Disclosed herein are a motor and impeller for a hair care appliance and a hair care appliance including the disclosed motor and impeller. The impeller which has a non-uniform distribution of its blades about the rotational axis (compared to a conventional impeller, in which the blades are uniformly distributed). In doing this, the pressure wave induced by the impeller will not be of a constant frequency. This has the effect of spreading the acoustic energy associated with the blade passes to other frequencies, which can lower the magnitude of the blade pass frequency relative to the noise floor.

It should also be noted that the blades should be unevenly distributed around the rotational axis in such a way that the center of mass of the impeller is still directly in line with the rotational axis. If this is not the case, then the offset center of mass will create a sinusoidal force quadratically proportional to the rotating speed. This imbalance force will create unwanted noise and vibration to the consumer.

Various exemplary impeller assemblies are provided. The exemplary impeller assemblies described herein have impeller blades that are unevenly distributed around the hub. The uneven distribution of the impeller blades can reduce the noise produced by the impeller assembly, as compared to a typical impeller assembly having evenly spaced blades. As a result, operation of the impeller assembly can be more pleasant on the ears of a user. The impeller assemblies can be used in a variety of devices, but in certain exemplary embodiments the impeller assemblies are configured for use in a hair dryer device.

FIGS. 1-8 illustrate one exemplary embodiment of an impeller assembly 208a having unevenly spaced impeller blades. As shown, the impeller assembly generally includes a hub body 232, a sleeve 248 disposed within the hub body 232, and a plurality of impeller blades 246a-246g, collectively referred to herein as impeller blades 246, extending radially outward from the hub body 232. The impeller assembly 208a can also include a plurality of vanes 252 extending between the sleeve 248 and the hub body 232. As further shown in the figures, the impeller assembly 208a is coupled to a motor assembly 210. In particular, the sleeve 248 is coupled to a drive shaft 230 of the motor 210 to enable the drive shaft 230 to cause rotational movement of the impeller assembly 208a. A person skilled in the art will appreciate that the impeller assembly 208a can be used with a variety of different motor assemblies or other assemblies configured to impart rotation to the impeller assembly 208a.

The hub body 232 can have a variety of configurations, but as shown the hub body 232 is in the form of a generally cylindrical hollow housing having a concave inner surface 234, a convex outer surface 236, and a hollow cavity or recess 237 extending therethrough. The shape and diameter of the hub body 232 can vary. As best shown in FIG. 3, the hub body 232 is generally bowl-shaped, and the convex outer surface 236 includes a closed end 239 and an open end 241. A rim 238 extends around the outer circumference of the hub body 232. As illustrated in FIG. 5, the closed end 239 includes an eyelet 244, as will be discussed in more detail below. A center of mass 285 of the impeller assembly corresponds to the eyelet 244.

As shown in FIG. 4, the sleeve 248 extends through the hub body 232 along a central longitudinal axis CL thereof. While the sleeve 248 can have a variety of configurations, the illustrated sleeve 248 is in the form of a hollow elongate shaft. Such a configuration enables a driveshaft 230 of the motor 210 to extend through the sleeve 248 and to couple to the eyelet 244 on the closed end 239 of the hub body. As further shown in FIG. 4, a plurality of vanes or fins 252 can extend radially outward from the sleeve 248 to the interior surface 234 of the hub body 232, such that the fins 252 extend between the sleeve 248 and hub body 232. Such a configuration can facilitate concentric positioning of the hub body 232 around the sleeve 248. In the illustrated embodiment, the fins 252 are spaced equidistant from each other around the circumference of the sleeve 248, however other spacing configurations can be utilized. Further, the illustrated embodiment has three fins, however the impeller assembly 208a can include any number of fins or can utilize other techniques for positioning the hub body 232 about the sleeve 248.

As indicated above, the hub body 232 can include a plurality of impeller blades 246 extending radially outward from the outer surface 236 thereof and spaced around an outer circumference of the hub body 232. As best shown in FIG. 5, each blade can have a shape in the form of a distorted rectangle, and can include a tapered edge 256 mounted on and extending along a length of the hub body 232, a curved edge 258 positioned opposite the tapered edge 256 and forming the outer-most edge of the blade, and first and second sides 260, 262 extending between the tapered edge 256 and the curved edge. The first side 260 can be positioned adjacent to the open end of the hub body 232, and the second side 262 can be positioned adjacent to the closed end of the hub body 232 where the eyelet is located. Each blade 246 can also include a first outer corner or vertex 268 and a second outer corner or vertex 270 on opposed ends of the tapered edge 256.

As indicated above, each blade 246 can extend from the open end 241 to the closed end 239 of the hub body 232 along the convex outer surface 236 of the hub body 232. However, as best shown in FIGS. 1-4, the blades 246 can be oriented at an angle relative to the central longitudinal axis CL with the curved edge 258 radially offset from the tapered edge 256. The blades 246 extend from the tapered edge 256 and extend radially outward to the curved edge 258. While the blades can have a 3-dimensional profile, similar to that of a wind turbine blade to aid in moving fluid using the blades 246, the thickness of the blades is contact along the length from the edge 256 to the edge 258. In an exemplary embodiment, the first edge of each blade 246 overlap the second edge of an adjacent blade 246.

As indicated above, in order to reduce noise the impeller blades 246 are unevenly distributed around the exterior surface 236 such that a distance D1 from the first vertex 268 of any given blade, for example blade 246a, to the first vertex 268 of a blade immediately adjacent in a clockwise direction, for example blade 246b, is different from a distance D2 from the first vertex 268 of blade 246a to the first vertex 268 of a blade immediately adjacent in a counterclockwise direction, for example blade 246g. The degree to which each blade is spaced from an adjacent blade can be random. In one exemplary embodiment, blade 246a and blade 246b are radially offset from one another by about 65 degrees, blade 246b and blade 246c are radially offset from one another by about 40 degrees, blade 246c and blade 246d are radially offset from one another by about 51 degrees, blade 246d and blade 246e are radially offset from one another by about 56 degrees, and blade 246e and blade 246f are radially offset from one another by about 51 degrees, blade 246f and blade 246g are radially offset from one another by about 49 degrees, and blade 246g and blade 246a are radially offset from one another by about 45 degrees, as best illustrated in FIG. 6. The degrees between the blades are measured using the angle from the center of the eyelet 244 to the corner of the blade 246 where the edge 258 meets the side 262. In order to guarantee a balanced impeller, two balancing conditions (shown below) must hold true, where Θ_i is the angle measured from the zero reference point. The zero reference point is Θ_i=0 degrees, and the balancing conditions include:

$\begin{array}{c}\sum _{i=1}^z\sin \left({\theta }_i\right)=0\\ \sum _{i=1}^z\cos \left({\theta }_{\dot{1}}\right)=0\end{array}$

As illustrated in FIGS. 7-8, the impeller assembly 208a and part of the motor body 210 can further include a cylindrical casing 298 disposed therearound. A plurality of spacers 304 can extend between the motor body 210 and the casing 298. The spacers 304 can define diffusion apertures 306 therebetween that can operate to direct airflow therethrough.

As illustrated by the arrows in FIG. 7, the impeller assembly 208a is configured to rotate about a rotational axis 283 in either rotational direction. The rotational axis 283 can directly correspond to the center of mass 285 of the impeller assembly 208a. Rotation of the impeller assembly 208a creates a pressure wave which produces audible noise. Pressure waves of a constant frequency will generate a single audible tone which is generally of high magnitude. Since the blades 246 of the illustrated embodiment are unevenly spaced, the pressure wave created by the rotation of the impeller assembly 208a produces multiple audible tones, but the magnitude of these tones will generally be lower than the single tone of an impeller assembly with evenly spaced blades. This reduces the unpleasant noises made by devices utilizing an impeller with uneven blade spacing. The rotation also produces a blade passage frequency, and the blade passage frequency is configured to be at least 10% less than a blade passage frequency of a similar impeller assembly with evenly distributed blades. A similar impeller assembly in this case would be an impeller assembly including all of the same features of impeller assembly 208a, except each blade of the plurality of impeller blades would be evenly spaced apart.

As indicated above, in one embodiment the impeller assembly can be configured for use in a hair dryer. FIG. 9 illustrates one exemplary embodiment of a hair care appliance 100. The illustrated hair care appliance is described in more detail in U.S. patent application Ser. No. 18/098,086, titled “Hot Brush,” filed on Jan. 17, 2023, which is incorporated by reference herein. As shown, the hair care appliance is in the form of a hot brush having a handle 200 coupled to a body 300. The handle 200 includes an inlet 102 at a proximal end 124 of the hair care appliance 100 and a plurality of outlets 104 arranged in the body 300. The fluid flow path 106 extends between the inlet 102 and outlets 104. The hair care appliance 100 can include a cord or cable 109 extending from the proximal end of the handle 200 and having electrical wires extending there through. A terminal end of the cord or cable 109 can include a plug 108 or similar connector configured to couple to a power source for allowing power to be delivered to the internal components of the hair care appliance 100. The hair care appliance can also include one or more user interfaces 110 on the handle 200 configured to allow user control of the device, and/or to provide visual indications or notifications in regard to an operational mode of the hair care appliance 100. In some embodiments, the handle 200 can include a rotatable selector 112 or similar switch-type element configured to select an operational mode from one or more mode settings. In some embodiments, the rotatable selector 112 can be configured as an actuator.

FIG. 10 illustrates the internal components of the handle 200, and as shown the handle 200 includes a printed circuit board (PCB) 206 at a proximal end 202 of the handle 200. The PCB 206 can include at least one data processor that can be communicatively coupled to a non-transitory computer-readable medium storing instructions, which when executed, cause the at least one data processor to perform operations associated with one or more operational modes of the hair care appliance 100. The PCB 206 can be communicatively coupled to a fan assembly 208 disposed in the handle 200 and including the impeller assembly 208a and motor body 210. The fan assembly 208 can draw air into the hair care appliance 100 through the inlet 102 at the proximal end 202 of the handle 200. The air can pass along the fluid flow path 106 through an inner lumen 212 to a heater assembly 214 positioned in the handle 200. Air can be heated by the heater assembly 214 and can continue along the fluid flow path 106 into the body 300. The PCB 206 can also be communicatively coupled to the heater assembly 214. The PCB 206 can be further communicatively coupled to the rotatable selector 112 on the handle 200 for receiving a user input selecting an operational mode of the hair care appliance 100. The PCB 206 can also include a controller 226 communicatively coupled to the fan assembly 208 and the heater assembly 214. The controller 226 can be configured to activate or deactivate the fan assembly 208 and the heater assembly 214. The controller 226 can be further communicatively coupled to the user interface 110 and the rotatable selector 112. Responsive to user inputs provided via the rotatable selector 112, the controller 226 can generate first control signals selectively activating or deactivating the fan assembly 208 and the heater assembly 214 and second control signals further controlling the user interface 110 to be selectively activated or deactivated in response to the first control signals. The handle 200 can include a number of additional components to aid in operation of the device and/or to improve performance. For example, as shown in FIG. 2, the handle 200 can include a heater coil 228 that can act as a resistor to reduce voltage supplied to the motor body 210. When the motor body 210 is on, the heater coil 228 is energized and heats air flowing therethrough.

In an aspect, an impeller can include blades that are unevenly spaced in a pseudo random distribution around a central axis of the impeller. For example, the pseudo random distribution can be formed by orienting one or more blades at different angles with respect to the central axis. The random, unevenly spaced distribution of blades can be formed on an impeller having any number of blades, without limit. As well, a variety of non-limiting random blade sizes and distribution patterns of blades can be envisioned.

The random spacing can be determined using a random seed. The random seed can be determined using a spacing parameter, D, corresponding to a magnitude of uneven spacing of the blades. Using a variety different values D and an interference function, an optimized spacing arrangement can be determined. The interference function can be represented as shown below, where in this equation n is an integer, j is the sqrt(−1) and Θ_i is the blade angle, and z is the total number of blades:

$F_{\mathrm{int}}\left(\omega \right)\equiv F_{\mathrm{int}}\left(n{\omega }_0\right)=F_{\mathrm{int}}\left(n\right)=\sum _{i=1}^z\exp \left(-j𝔫{\theta }_i\right)$

The interference function shown above can act as a filter for the sound spectrum, which can alter the sound power at a give frequency as shown in the plot 250 of FIG. 11. The function becomes normalized when the function F_int(n) is divided by the number of blades, z, as shown in FIGS. 11 and 12.

The interference function can be computed at values f/f0, where f0 is the fundamental frequency of rotation. A frequency of 60,000 RPM was used, so the fundamental is 1000 Hz. Therefore, each value along the x-axis is the nth frequency multiple of the fundamental. As seen at line 205, which represents evenly spaced blades only has peaks at 15, 30, 45, etc.—which is multiples of the number of blades (15 blades). Thus, a perfectly spaced impeller will have large tonal noise at 15 times the rotational speed (as previously explained), as well as harmonics at 30, 45, 60, etc.

This interference function is a measure of how much the acoustic energy is spread out to other frequencies. Note how the magnitude of the peaks at n=15 are lower for the unevenly spaced designs, as this energy goes to other harmonics. To optimize the impeller blade design, it is advantageous to lower the peak at 15 as much as possible, thus reducing the blade passage frequency as much as possible.

As shown in plot 300 of FIG. 12, results of an interference function for an evenly spaced impeller are provided as line 305 with respect to results for an impeller with spacing generated according to the methods described herein having D value of 3.8 and provided as line 310. In the plot 300, the value at n=15 is significantly reduced in line 310 compared to the value of line 305, as the energy has been spread to other multiples of the fundamental frequency. The values at n=24 and n=39 are significant, but at 60,000 RPM, these peaks correspond to frequencies at 24 KHz and 39 kHz, respectively. This is outside of the human hearing range so they are irrelevant. It can be advantageous that acoustic energy is being spread to frequencies outside of the human hearing range.

Outside of using an interference function to design an optimized blade arrangement, it may help to think of the pressure that a spot on the housing sees as a sawtooth function. The approximate triangular-shaped peaks will be what a fixed location sees from each blade passing event. The frequency spread will be determined by the spacing of the triangular peaks, with more variation sending more energy to the side bands. As shown in FIGS. 13 and 14, data verifying the results of the optimization methods described herein is provided. Plot 400 of FIG. 13 shows the relative pressures over time for 1 rotation for evenly spaced blades (line 405) versus the optimized design (line 410). Amplitudes were set to 1, but would likely be much less. Plot 500 of FIG. 14 shows the frequency spectrum for the time series in FIG. 14. For the evenly spaced blades (line 505), we see a huge spike at 15000 Hz as expected. For the unevenly spaced optimized design (line 510), we see a significant lowering of that spike, and the energy being sent to other harmonics of the fundamental (all integer multiples of 1000 Hz).

FIG. 15 is a perspective view of an exemplary embodiment of an impeller 600 having a plurality of blades 605 arranged in a pseudo random, unevenly spaced arrangement determined according to the methods described herein.

The impeller assembly disclosed herein can be used with a number of other hair care appliances, such as the hair care appliances disclosed in U.S. patent application Ser. No. 17/737,518, titled “Hair Care Appliance,” filed on May 5, 2022, U.S. patent application Ser. No. 18/169,645, titled “Hair Care Appliance With Cooled Circuitry,” filed on Feb. 15, 2023.

Certain exemplary embodiments have been described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the systems, devices, and methods disclosed herein. One or more examples of these embodiments have been illustrated in the accompanying drawings. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. Further, in the present disclosure, like-named components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-named component is not necessarily fully elaborated upon.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the present application is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated by reference in their entirety.

Claims

1. An impeller assembly, comprising: a generally cylindrical hollow hub body;a sleeve extending through the hub body, the sleeve includes a central bore therethrough configured to receive a driveshaft for coupling the impeller assembly to a motor;a plurality of vanes extending between the sleeve and the hub body; anda plurality of impeller blades extending radially outward from the hub body and being unevenly distributed around a circumference of the hub body.

2. The impeller assembly of claim 1 wherein each impeller blade of the plurality of impeller blades is angled relative to a longitudinal axis of the hub body.

3. The impeller assembly of claim 1 wherein the plurality of impeller blades comprises an odd number of impeller blades.

4. The impeller assembly of claim 1 wherein each blade of the plurality of impeller blades includes an outer rim having a first vertex and a second vertex, and wherein a first distance between the first vertex of each impeller blade and a corresponding first vertex of a consecutive impeller blade in the clockwise direction differs from a second distance between the first vertex of each impeller blade and a corresponding first vertex of a consecutive impeller blade in the counterclockwise direction.

5. The impeller assembly of claim 1 wherein a center of mass of the impeller assembly is positioned along a longitudinal axis of the hub body.

6. The impeller assembly of claim 1, wherein rotation of the hub body is configured to cause the plurality of impeller blades to create a pressure wave, and wherein at least two of plurality of impeller blades create pressure waves at different frequencies.

7. The impeller assembly of claim 1, further comprising a cylindrical covering disposed around the plurality of impeller blades.

8. The impeller assembly of claim 7, wherein the cylindrical covering includes a plurality of diffusing apertures.

9. An impeller assembly comprising: a hub body including an inner surface and an outer surface, wherein the inner surface comprises a recess;a sleeve extending through a center of the hub body, wherein the sleeve is configured to receive a driveshaft to physically couple the impeller assembly to a motor;a plurality of vanes extending from the sleeve to the inner surface; anda plurality of impeller blades extending radially outward from the outer surface and spaced around a circumference of the outer surface, wherein each blade of the plurality of impeller blades includes an outer edge having a first vertex and a second vertex, and wherein a first distance between the first vertex of each blade and a corresponding first vertex of an immediately adjacent blade in the clockwise direction differs from a second distance between the first vertex of each blade and a corresponding first vertex of an immediately adjacent blade in the counterclockwise direction.

10. The impeller assembly of claim 9, wherein each of the plurality of impeller blades is angled related to a longitudinal axis of the sleeve.

11. The impeller assembly of claim 9, wherein a center of mass of the impeller assembly is positioned along a longitudinal axis of the hub body.

12. The impeller assembly of claim 9, wherein rotation of the hub body is configured to cause the plurality of impeller blades to create a pressure wave, and wherein at least two of plurality of impeller blades have pressure waves that differ from one.

13. The impeller assembly of claim 9, wherein rotation of the hub body is configured to cause the plurality of impeller blades to produce a blade passage frequency with a magnitude in the sound pressure level range of 55 to 65 dB(A) when measured at 1 meter away from the plurality of impeller blades.

14. The impeller assembly of claim 9, wherein the plurality of impeller blades comprises an uneven number of impeller blades.

15. The impeller assembly of claim 9, further comprising a cylindrical covering disposed around the plurality of impeller blades.

16. The impeller assembly of claim 15, wherein the cylindrical covering includes a plurality of diffusing apertures.

17. The impeller assembly of claim 9, wherein each of the plurality of vanes is spaced equidistant from each other around the sleeve.