Low Noise Air Movement Generator
A low noise air generator possessing improved characteristics thereby reducing noise while maintaining or improving air flow generation and output is provided. The device may include an impeller with multiple blades, a noise reduction structure connected to a distal end of the multiple blades, an impeller housing, a tapered motor mounting surface, a heating element, a mechanical air filter, and/or an electrostatic precipitation air filter.
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This application claims priority to U.S. provisional application Ser. No. 61/632,356 filed Jan. 23, 2012, which is incorporated herein by reference in its entirety.
TECHNOLOGY FIELDThe present invention relates to air movement generators. More specifically, the present invention relates to a low noise air movement generator of compact size for use in portable air moving devices.
BACKGROUNDWhenever a mechanical system has been utilized to generate air movement one of the disadvantages is the noise produced by the device. This issue is especially acute for impellers that revolve at high revolutions per minute [RPM]. The noise produced can be unwanted and oftentimes uncomfortable to any person within hearing distance. Many times this noise is high pitched and difficult for the human mind to overlook.
The noise produced by the air generators in portable devices, such as for example, computers, cooling fans, heaters, air cleaners, air purifiers, and humidifiers, is a particularly difficult problem to address since the device to be effective must be located near the user. This problem is made worse if the portable device requires the use of more than one air generator.
Some conventional devices have responded to this problem in one of several manners. One manner is to reduce the RPM of the impeller. Although this mitigates the noise produced to some degree it also degrades the performance of the air flow generation.
Another response has been to construct the portable device with additional sound attenuation structures and the like. This solution can reduce the audible noise detected but the additional structure often increases the cost and reduces the air flow performance of the portable device. Increasing the cost of the portable device makes it less desirable to consumers and manufacturers alike.
Axial type impellers can produce and move large volumes of air efficiently; however axial impellers are especially disposed to produce noise because of the speed of the blade tips and the need for support structures that are often located near the blades. As a single blade passes the support structures the air flow between the blade and the support structure produces noise. This production of noise with an axial impeller increases as the RPM of the impeller increases.
In view of the deficiencies of conventional air movement generators, what is needed is a low noise air movement generator, especially configured for portable devices that are intended to be utilized while located near the user.
SUMMARYThe low noise air movement generator according to embodiments of the present invention provides a simple yet economical structure that preserves or improves the performance characteristics of axial type impeller air movement generator while significantly reducing the noise generated.
As described and shown, the low noise air movement generator uses a novel noise attenuation structure incorporated on the impeller. Additional noise reduction can be achieved by the inventive mounting structures that locate all motor support members at a sufficient distance from the rotating impeller to reduce the interaction of the impeller with the motor support members. One advantageous characteristic of the low noise air movement generator of the current invention is the compact design. The compact size increases the ability of the low noise air movement generator to be used in various portable devices.
Another aspect of the low noise air movement generator is ease of manufacturing, which requires no specialized equipment. This allows the low noise air movement generator to be economically fabricated, which further serves to applicability of the device.
One aspect of the invention includes an axial flow impeller including a hub, multiple blades, and a noise attenuation structure connected to the distal ends of the multiple blades.
Another aspect of the invention includes a motor disposed substantially within an internal cavity of the hub. The motor may include a permanent magnet rotor that is assembled in the hub and a stator rotatably connected to the rotor.
Yet another aspect is mounting a single or multiple low noise air movement generator(s) as part of the structure for a portable air moving device such as, for example, a portable space heater, a portable fan, a portable air cleaner, a portable air purifier or a portable humidifier.
Another aspect of the invention is a mounting structure connected to the motor having a conical surface in which the conical surface fits into a mounting socket of similar form.
Another aspect of the invention includes a housing the impeller is located within and connected to the housing by a support member, the support member being located at a predetermined distance from the impeller to reduce the noise produced by the rotation of the impeller.
The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following Figures:
As shown interior space 256 defined by impeller housing 254 has a similar shape to noise attenuation structure 216 and is slightly larger to maintain a minimum clearance between noise attenuation structure 216 and the impeller housing 254.
Also shown in
As shown in
It is contemplated that motor 130 may be a brushless direct current (DC) motor. Brushless DC motors have advantages over other motor types including for example: 10% to 50% higher efficiency depending on the application, longer operating life because there are no brushes to wear out, less friction, less noise and a lower weight to torque ration which is desirable and useful in portable devices.
Pre-determined distance “A” is shown as the minimum dimension measured from exhaust edge 217b to impeller support members 252 in the direction of air flow 300; however, the invention is not so limited. It is contemplated that pre-determined distance “A” may be a minimum distance measured from intake edge 217a to impeller support members 252 in the opposite direction of flow of air flow 300. In short, impeller support members 252 could be located on the opposite side of impeller 218 corresponding to intake edge 217a. In a preferred embodiment, pre-determined distance “A” is at least 25% of the axial distance measured between intake edge 217a and exhaust edge 217b of impeller 218.
Heater assembly 800 may include multiple low noise air movement generators 802, multiple airflow transitions 870, and more than one heating element 880. As can be appreciated, one or more heater assembly 800 could be located in a portable electric heater.
According to another embodiment,
It is also contemplated that multiple low noise air movement generators 200 could be used with mechanical filter 980 of
In short, the low noise air movement generators 100, 200 and 600 of the current invention are capable of reducing noise at high and low speeds. This noise reduction when utilized in air moving devices, as illustrated and described in
As shown in the embodiment of
Although the embodiment of
Although the invention has been described with reference to exemplary embodiments, it is not limited thereto. Rather, it should be construed to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the true spirit and scope of the present invention.
Claims
1. A portable air moving device comprising;
- a housing having an air intake opening and an air exit opening;
- an interior space defined by said housing;
- at least one air generator located within said housing comprising; an impeller comprising; a hub comprising; an outer wall; a front wall; an internal cavity defined by said outer wall and said front wall; multiple blades connected to said outer wall of said hub and extending radially outward from said hub toward a distal end; a noise attenuation structure connected to said distal end of more than one of said multiple blades comprising; a circumferential wall having a substantially cylindrical form; an axis of said cylindrical form; an intake edge of said cylindrical form; an exhaust edge of said cylindrical form offset a distance from said intake edge along said axis of said cylindrical form; a motor disposed substantially within said internal cavity of said hub, said motor comprising; a permanent magnet rotor fixedly assembled to said hub; a stator rotatably connected to said rotor, said hub, said multiple blades, and said noise attenuation structure;
- wherein a rotation of said impeller of said at least one air generator induces an intake air flow into said air intake opening of said housing and simultaneously generates an exhaust air flow from said air exit opening of said housing.
2. The portable air moving device of claim 1, further comprising an electric heating element located in said interior space of said housing, wherein a temperature of said exhaust air flow is greater than a temperature of said intake air flow.
3. The portable air moving device of claim 1, further comprising an air filter located in said interior space of said housing, wherein substantially all of said intake air flow passes through said air filter prior to exiting said housing through said air exit opening as said exhaust air flow.
4. The portable air moving device of claim 3, wherein said air filter utilizes a mechanical filter to clean the air.
5. The portable air moving device of claim 3, wherein said air filter utilizes an electrostatic precipitator to clean the air.
6. The portable air moving device of claim 1, wherein said hub, said multiple blades and said noise attenuation structure of said impeller comprise a unitary structure.
7. The portable air moving device of claim 1, further comprising an impeller housing comprising; wherein said air generator is located substantially within said interior space defined by said impeller housing wall and connected to said impeller housing wall by said at least one impeller support member, said at least one impeller support member being connected to said motor and extending outwardly to said impeller housing wall.
- an impeller housing wall defining an interior space;
- an inlet opening;
- an outlet opening;
- at least one impeller support member; and
8. The portable air moving device of claim 7, wherein said impeller housing wall and said at least one impeller support member comprise a unitary structure.
9. The portable air moving device of claim 7, further comprising an offset distance “A” of said at least one impeller support member defined by a minimum distance from said exhaust edge of said noise attenuation structure to said impeller support member measured in a direction of the air flow through said air generator, wherein said minimum distance is at least 25% of said offset distance between said intake edge and said exhaust edge of said noise attenuation structure.
10. The portable air moving device of claim 7, further comprising an offset distance “A” of said at least one impeller support member defined by a minimum distance from said intake edge of said noise attenuation structure to said impeller support member measured in a direction opposite a direction of the air flow through said air generator, wherein said minimum distance is at least 25% of said offset distance between said intake edge and said exhaust edge of said noise attenuation structure.
11. The portable air moving device of claim 1, wherein said intake edge further comprises an intake funnel including an arcuate surface extending radially outward relative to said hub.
12. The portable air moving device of claim 1, wherein said intake edge further comprises an intake funnel including a conical surface extending radially outward relative to said hub.
13. The portable air moving device of claim 1, wherein said motor comprises a brushless direct current motor.
14. An air generator comprising; wherein a rotation of said impeller generates an air flow radially confined by said outer wall of said hub and said circumferential wall of said noise attenuation structure; and wherein said air flow has a direction of flow from said intake edge toward said exhaust edge of said noise attenuation structure and said direction of flow is substantially parallel to said rotational axis of said impeller.
- an impeller comprising; a hub comprising; an outer wall; a front wall; an internal cavity defined by said outer wall and said front wall; multiple blades connected to said outer wall of said hub and extending radially outward from said hub toward a distal end;
- a noise attenuation structure connected to said distal end of more than one of said multiple blades comprising; a circumferential wall having a substantially cylindrical form; an axis of said cylindrical form; an intake edge of said cylindrical form; an exhaust edge of said cylindrical form offset a distance from said intake edge along said axis of said cylindrical form;
- a motor disposed substantially within said internal cavity of said hub, said motor comprising; a permanent magnet rotor fixedly assembled to said hub; a stator rotatably connected to said rotor, said hub, said multiple blades, and said noise attenuation structure;
15. The air generator of claim 14, wherein said hub, said multiple blades and said noise attenuation structure of said impeller comprise a unitary structure.
16. The air generator of claim 14, further comprising a mounting structure fixedly connected to said stator, said mounting structure comprising;
- a first diameter located proximate said hub and a second diameter offset a specified distance from said first diameter and said hub;
- an arcuate surface extending between said first diameter and said second diameter; and
- wherein said first diameter is larger than said second diameter and said arcuate surface comprises a substantially conical surface.
17. The air generator of claim 16, further comprising at least one fastener to attach said air generator to a portable air moving device, wherein a longitudinal length of said fastener is oriented substantially parallel to said rotational axis of said impeller.
18. The air generator of claim 14, further comprising an impeller housing comprising; wherein said impeller is located within said interior space defined by said impeller housing wall and connected to said impeller housing wall by said at least one impeller support member, said impeller support member being connected to said motor and extending outwardly to said impeller housing wall.
- an impeller wall defining an interior space;
- an inlet opening;
- an outlet opening;
- at least one impeller support member; and
19. The air generator of claim 18, wherein said impeller housing wall and said impeller support member comprise a unitary structure.
20. The air generator of claim 18, further comprising an offset distance “A” of said at least one impeller support member defined by a minimum distance from said exhaust edge of said noise attenuation structure to said impeller support member measured in a direction of the air flow through said air generator, wherein said minimum distance is at least 25% of said offset distance between said intake edge and said exhaust edge of said noise attenuation structure.
21. The air generator of claim 18, further comprising an offset distance “A” of said at least one impeller support member defined by a minimum distance from said intake edge of said noise attenuation structure to said impeller support member measured in a direction opposite a direction of the air flow through said air generator, wherein said minimum distance is at least 25% of said offset distance between said intake edge and said exhaust edge of said noise attenuation structure.
22. The air generator of claim 14, wherein said intake edge further comprises an intake funnel including an arcuate surface extending radially outward relative to said hub.
23. The air generator of claim 14, wherein said intake edge further comprises an intake funnel including a conical surface extending radially outward relative to said hub.
24. An impeller and motor assembly comprising; wherein said first, said second and said third axes are substantially co-axial relative to one another; and wherein a rotation of said permanent magnetic rotor, said hub, said multiple blades, and said noise attenuation structure generates an air flow from said intake edge toward said exhaust edge and radially confined by said outer wall of said hub and said circumferential wall of said noise attenuation structure.
- a motor comprising; a permanent magnet rotor; a stator rotatably connected to said permanent magnet rotor; a first axis defined by an axis of rotation of said rotor;
- an impeller hub fixedly connected to said permanent magnet rotor comprising; an outer wall having a cylindrical form; a front wall; an internal cavity defined by said outer wall and said front wall and said permanent magnet rotor located substantially within said cavity; a second axis defined by an axis of said cylindrical form of said impeller hub;
- a noise attenuation structure comprising; a circumferential wall having a substantially cylindrical form; an intake edge of said cylindrical form; a third axis of said cylindrical form being defined by said circumferential wall; an exhaust edge of said cylindrical form offset a distance from said intake edge along said third axis;
- multiple impeller blades connected to said outer wall of said hub and extending radially outward from said hub toward and connected to said circumferential wall of said noise attenuation structure;
25. The impeller and motor assembly of claim 24, wherein said hub, said multiple blades and said noise attenuation structure comprise a unitary structure.
Type: Application
Filed: Jan 15, 2013
Publication Date: Jul 25, 2013
Applicant: Lasko Holdings, Inc. (Wilmington, DE)
Inventor: Lasko Holdings, Inc. (Wilmington, DE)
Application Number: 13/742,057
International Classification: F04D 29/66 (20060101); F04D 25/06 (20060101);