TECHNOLOGY FIELD
The 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.
BACKGROUND
Whenever 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.
SUMMARY
The 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.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIGS. 1A and 1B are front and rear perspective views respectively of an exemplary embodiment of a low noise air movement generator;
FIGS. 2A and 2B are front and rear perspective views respectively of another exemplary embodiment of a low noise air movement generator;
FIG. 3 is a cross section view of the low noise air movement generator of FIG. 1A;
FIGS. 4A and 4B are cross section views of the low noise air movement generator of FIG. 3 with motor mounting structures un-mounted and mounted respectively;
FIG. 5 is a cross section view of the low noise air movement generator of FIG. 2A;
FIG. 6 is a cross section view of another exemplary embodiment of a low noise air movement generator;
FIG. 7 is a view of a portable device with a low noise air movement generator;
FIG. 8 is an exploded perspective view of another embodiment of a portable device with a low noise air movement generator;
FIG. 9 is a horizontal cross section view of another embodiment of a portable device with a low noise air movement generator;
FIG. 10 is a view of another embodiment of a portable device with a low noise air movement generator;
FIG. 11 is a noise comparison chart showing a sonic analysis of a conventional fan and a low noise air movement generator of FIGS. 2A and 2B;
FIG. 12 is another noise comparison chart showing a sonic analysis of a conventional fan and a low noise air movement generator of FIGS. 2A and 2B;
FIG. 13 is front view of another embodiment of a low noise air movement generator;
FIG. 14 is a cross-sectional view of the low noise air movement generator of FIG. 13;
FIG. 15 is a front view of a matrix mounting of multiple low noise air movement generators; and
FIG. 16 is a cross-sectional view of the matrix mounting of multiple low noise air movement generators of FIG. 15.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
FIGS. 1A and 1B are a front and rear perspective view, respectively, of an exemplary embodiment of low noise air movement generator 100. Impeller 118 may include multiple blades 110 extending outward from hub 112 toward distal ends 114. Distal ends 114 of blades 110 are attached to noise attenuation structure 116. Motor 130 is located substantially within hub 112 of the impeller 118. Mounting structure 140 is attached to motor 130. Also shown is cross section plane 3-3 that corresponds to FIG. 3.
FIGS. 2A and 2B are front and rear perspective view respectively of an exemplary embodiment of low noise air movement generator 200. Impeller 218 may include multiple blades 210 extending outward from hub 212 toward distal ends 214. Distal ends 214 of blades 210 are attached to noise attenuation structure 216. Motor 230 is located substantially within hub 212 of the impeller 218. Impeller support adaptor 250 is attached to motor 130. Impeller support members 252 are attached to impeller support adaptor 250 and extend outward to connect with impeller housing 254. As can be seen, impeller housing 254 may include interior space 256 in which impeller 218 is located when assembled.
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 FIGS. 2A is cross section plane 5-5 that corresponds to FIG. 5.
As shown in FIGS. 1A, 1B, 2A, and 2B, impeller 118 and 218 may be a unitary construction and formed of polymer, die cast metal, or welded construction. In a similar fashion, impeller housing 254, impeller support members 252, and impeller support adaptor 250 of FIGS. 2A and 2B may be a unitary construction and formed of polymer.
FIG. 3 is a cross section view of low noise air movement generator 100 of FIG. 1A. As shown intake edge 117a of noise attenuation structure 116 is arcuate while exhaust edge 117b is straight. Motor 130 is located substantially within hub 112 of the impeller 118. Motor 130 may include permanent magnet rotor 131 attached to hub 112, shaft 133, and bearings 134. Also shown is power control board (PCB) 136. When electrical power is supplied, PCB 136 conditions the power and energizes stator coils 132 and stator135. Magnetic rotor 131 rotates the impeller 118. The rotation of impeller 118 generates air flow 300 between hub 112 and noise attenuation structure 116. Mounting structure 140 is fixedly assembled to motor 130.
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.
FIGS. 4A and 4B are cross section views of low noise air movement generator 100 of FIG. 3 with mounting structure 140 in an un-mounted configuration (see FIG. 4A) and mounted configuration (see FIG. 4B). Mounting structure 140 attached to motor 130 has tapered surface 420 defined by first diameter 422 and second diameter 424. First diameter 422 is larger than second diameter 424 and defines tapered surface 420. Mounting socket 400 has corresponding tapered surface 402. As shown in FIG. 4B, mounting structure 140 is fit into the mounting socket 400 and held in place with at least fastener 410. Although fastener 410 is shown as a flat head screw, the invention is not so limited. Assembly of mounting socket 400 to mounting structure 140 may be accomplished with snaps, Velcro, other threaded fasteners, adhesives, and the like without departing from the spirit of the invention.
FIG. 5 is a cross section view of low noise air movement generator 200 of FIG. 2A. Low noise air movement generator 200 includes impeller housing 254, at least one impeller support member 252, and impeller support adaptor 250. As shown intake edge 217a of noise attenuation structure 216 is conical. Impeller support members 252 are offset from exhaust edge 217b of the impeller 218 by a pre-determined distance “A”. Pre-determined distance “A” insures that air flow 300 does not create undesired noise when exiting impeller 218 as multiple blades 210 of impeller 218 passes impeller support member 252 during rotation.
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.
FIG. 6 is a cross section view of low noise air movement generator 600, according to an additional embodiment. As shown, intake edge 617a of noise attenuation structure 616 does not include an arcuate or conical form but is instead straight or nearly straight as is exhaust edge 617b. Also shown is mounting structure 640 connected to motor 130. Mounting structure 640 can be adapted with snaps, fasteners, adhesives, and the like for the purposes of mounting low noise air movement generator 600. Other features of low noise air movement generator 600 of FIG. 6 are similar to those described in FIG. 3. In particular, motor 130 is located substantially within hub 612 of the impeller 618. The rotation of impeller 618 generates air flow 300 between hub 612 and noise attenuation structure 616. Impeller 618 may include multiple blades 610 extending outward from hub 612 toward distal ends that are attached to noise attenuation structure 616.
FIG. 7 is a vertical cross section view through portable air moving device 700 utilizing one or more low noise air movement generator 701. Device 700 in FIG. 7 is a portable fan which may include multiple low noise air movement generators 701 arranged in a vertical configuration. Although shown in a vertical configuration, multiple low noise air movement generators 701 could be arranged horizontally or in a matrix without departing from the spirit of the invention. Multiple air generators 701 are similar to the embodiments shown in FIGS. 1A, 1B, 3, 4A and 4B. As can be seen, the direction of air flows 762 relative to motor 130 and impeller 118 is in in the opposite direction of the previous embodiments. This facilitates the incorporation of mounting socket 400 into intake grill 720 of the device. Multiple air flows 762 combine to generate total air flow 760 exiting through exhaust grill 730. Also shown are housing 710, housing support 750, and base 740.
FIG. 8 is a view of an embodiment in which heater assembly 800 utilizes low noise air movement generator 802 used in combination with airflow transition 870 and heating element 880. Similar to low noise air movement generator 200 of FIG. 5, low noise air movement generator 802 may include impeller housing 854, impeller support members 852, impeller 818, impeller support adaptor 850 and motor 130. Airflow transition 870 is utilized to assemble low noise air movement generator 802 to heating element 880 and creates a smooth transition of the air flow 890 as it exits low noise air movement generator 802 and enters heating element 880. Heating element 880 is assembled into cavity 872, and low noise air movement generator 802 is assembled to airflow transition 870 via mounting holes 873 and fasteners (not shown).
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, FIG. 9 is a horizontal cross section view of portable air cleaning device 900 with a low noise air movement generator 200 used in combination with mechanical air filter 980. Air is drawn into housing 910 of device 900 through intake grill 920 and forced through the mechanical air filter 980. Filtered air 960 exits housing 910 through exhaust grill 930. Mechanical air filter 980 may be a standard or non-standard pleated air filter and may include odor absorbing materials such as carbon or baking soda. As shown in FIG. 9, low noise air movement generator 200 is located prior to the mechanical air filter 980 with respect to air flow direction. It is contemplated that the low noise air movement generator 200 may be located subsequent to the mechanical air filter 980 with respect to air flow direction without departing from the spirit of the invention.
FIG. 10 is a horizontal cross section view of portable air cleaning device 1000 with low noise air movement generator 200 used in combination with electro-static precipitator (ESP) type air filter 1080 which may include ion emitters 1082 and collector plates 1084, according to an additional embodiment. Air is drawn into housing 1010 of device 1000 through intake grill 1020 and passes ion emitters 1082. Particles in the air are charged with the ions. Subsequently, the air passes through collector plates 1084 that are charged so as to attract the charged particles in the air. The charged particles adhere to collector plates 1084 and clean air exits collector plates 1084 and subsequently passes though low noise air movement generator 200 and exits device 1000 via exhaust grill 1030. As shown in FIG. 10, low noise air movement generator 200 is located subsequent to ESP type air filter 1080 with respect to the air flow direction. It is contemplated that low noise air movement generator 200 may be located prior to the ESP type air filter 1080 with respect to the air flow direction without departing from the spirit of the invention.
It is also contemplated that multiple low noise air movement generators 200 could be used with mechanical filter 980 of FIG. 9 or ESP filter 1080 of FIG. 10 to achieve larger and more varied configurations. Such multiple low noise air movement generators 200 could be arranged in vertical or horizontal columns or a matrix having rows and columns.
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 FIGS. 7, 8, 9, and 10, is a distinct advantage for the end user.
FIG. 11 is a noise comparison chart showing a sonic analysis at a high speed RPM 1120 of 3000 of conventional fan 1100 and low noise air movement generator 200 similar to FIGS. 2A, 2B and 5. Conventional fan 1100 does not include noise attenuation structure 216 or the pre-determined offset distance A for impeller support structure 252 as shown and described. As shown, conventional fan 1100 shows elevated noise levels 1110 between frequencies of 200 to 400 Hz. Low noise air movement generator 200 removes elevated noise levels 1110. The human ear therefore does not register elevated noise levels 1110 with low noise air movement generator 200 as the noise levels are not present and perceives a less high pitched noise and buzzing, thereby creating a more pleasant ambient.
FIG. 12 is a noise comparison chart showing a sonic analysis of conventional fan 1200 and low noise air movement generator 200 similar to FIGS. 2A, 2B and 5. Conventional fan 1200 does not include noise attenuation structure 216 or the pre-determined offset distance A for impeller support structure 252 as shown and described. The RPM 1220 of 2500 of the impeller for both conventional blower 1200 and low noise air movement generator 200 was slower than the RPM 1120 associated with the chart of FIG. 11. Lowering the RPM of the impeller is a conventional method to mitigate noise. Regardless of the lower RPM, conventional fan 1200 shows elevated noise levels 1210 between frequencies of 500 to 600 Hz. Low noise air movement generator 200 removes elevated noise levels 1210.
FIGS. 13 and 14 are a front view and a cross-sectional view respectively of low noise air movement generator 1300, according to another embodiment. FIG. 14 is a cross-sectional view along cross section vertical plane 14-14 of FIG. 13. Included in the embodiment are similar features of the embodiments shown in FIGS. 4A, 4B, and 5. The inclusion of mounting structure 140 on a motor 130, similar to FIGS. 4A and 4B, and incorporating mounting socket 1312, similar to FIGS. 4A and 4B, into the impeller support adaptor 1310, similar to FIG. 5, has several advantages. As shown, the impeller 118, motor 130 and mounting structure 140 can be mass produced as a sub-assembly coinciding with 1301. Sub-assembly 1301 can subsequently be mounted into multiple mounting structures and configurations. In the embodiment shown, mounting plate 1324, impeller hole 1322, impeller support structure 1320, impeller support adaptor 1310, and mounting socket 1312 are a unitary construction. 1360 represents the direction of air flow.
FIG. 15 is a front view of a matrix mounting 1500 of multiple sub-assemblies 1301 similar to the embodiment shown in FIGS. 13 and 14. As shown, the multiple sub-assemblies 1301 are arranged and mounted in close proximity relative to each other in positions labeled X and Y.
FIG. 16 is a cross-sectional view along cross section vertical plane 16-16 of FIG. 15. As can be seen, sub-assemblies 1301 mounted in positions labeled X are offset by dimension “Z” 1602 in the direction of the air flow 1660, while sub-assemblies 1301 mounted in positions labeled Y are offset by dimension “Z” 1604 in the opposite direction of the air flow 1660. Offsetting subassemblies 1301 as shown allows the radial distances between positions X and Y to be minimized as shown in FIG. 15.
As shown in the embodiment of FIGS. 15 and 16, mounting plate 1524, including multiple impeller holes 1522, multiple impeller support structures 1520, multiple impeller support adaptors 1510, and multiple mounting sockets 1512, may be of unitary construction. Multiple sub-assemblies 1301 can subsequently be mounted onto the single mounting plate 1524.
Although the embodiment of FIGS. 15 and 16 show two columns and three rows, the invention is not so limited. It is contemplated that one or more columns may be used in combination with one or more rows without departing from the spirit of the invention. As can be appreciated, the embodiment of FIGS. 15 and 16 can be incorporated into various air moving devices, such as for example the devices illustrated by FIGS. 7, 8, 9, and 10.
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.
Patent Application
20130189129
