US20120211300A1 - System method and devices for windage noise damping in induction motor - Google Patents
System method and devices for windage noise damping in induction motor Download PDFInfo
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- US20120211300A1 US20120211300A1 US13/031,473 US201113031473A US2012211300A1 US 20120211300 A1 US20120211300 A1 US 20120211300A1 US 201113031473 A US201113031473 A US 201113031473A US 2012211300 A1 US2012211300 A1 US 2012211300A1
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- 238000013016 damping Methods 0.000 title claims abstract description 25
- 230000006698 induction Effects 0.000 title claims abstract description 24
- 238000000034 method Methods 0.000 title claims description 17
- 238000001816 cooling Methods 0.000 claims abstract description 66
- 238000004891 communication Methods 0.000 claims abstract description 24
- 239000012080 ambient air Substances 0.000 claims abstract description 10
- 230000008878 coupling Effects 0.000 claims description 3
- 238000010168 coupling process Methods 0.000 claims description 3
- 238000005859 coupling reaction Methods 0.000 claims description 3
- 239000011358 absorbing material Substances 0.000 claims 2
- 239000003570 air Substances 0.000 description 12
- 238000010276 construction Methods 0.000 description 11
- 238000003491 array Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 239000006260 foam Substances 0.000 description 4
- 238000009434 installation Methods 0.000 description 4
- 230000001902 propagating effect Effects 0.000 description 4
- 125000006850 spacer group Chemical group 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 1
- 239000006261 foam material Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K9/00—Arrangements for cooling or ventilating
- H02K9/02—Arrangements for cooling or ventilating by ambient air flowing through the machine
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/20—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
- H02K5/207—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium with openings in the casing specially adapted for ambient air
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/24—Casings; Enclosures; Supports specially adapted for suppression or reduction of noise or vibrations
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
- H02K2213/09—Machines characterised by the presence of elements which are subject to variation, e.g. adjustable bearings, reconfigurable windings, variable pitch ventilators
Definitions
- the invention relates to noise reduction systems for induction, motors, and more particularly baffled ducts that may be fitted to motor cooling vents in order to dampen windage noise propagation caused by rotating motor shafts and rotors.
- Operating induction motors generate windage noise, caused by the rotating shaft, rotor and related rotating hardware.
- the windage noise propagates through motor cooling airflow paths that provide a heat transfer path out of the motor housing, including any external shrouds or other motor enclosures, via housing cooling vents. While the motor housing frame, external shrouds and other enclosures absorb or deaden some windage noise, the housing cooling vents enable noise propagation directly to surrounding ambient air. It is desirable to minimize noise exposure to workers who are located near operating motors, especially in the frequency range of 400-4000 Hz that has a greater impact on human hearing than higher or lower frequencies.
- baffle duct construction is modified to decrease spacing between baffles so as to dampen the relatively shorter wavelength of higher noise frequencies, overall cooling airflow performance of the cooling vent decreases to an unacceptable performance level.
- adjacent baffle spacing of 5.5 inches (140 mm) is sufficient to dampen a 400 Hz noise frequency.
- Such relatively wide adjacent baffle spacing provides for sufficient air flow rate- and volume into the motor cooling vent.
- a 4000 Hz noise frequency may require baffle parallel spacing of only 0.001 inch. (0.028 mm) to dampen sufficiently that frequency. Laterally spacing all baffles with a gap of 0.001 inch would unduly restrict air flow into the motor cooling vent.
- baffle dampers potentially sacrifice higher frequency noise attenuation when their shorter wavelengths pass between baffles set at the minimum baffle lateral spacing.
- baffle ducts provide a single solution for all applications, whereas different applications might benefit from baffle ducts constructed to meet the noise damping needs of a specific motor design or application for a motor design.
- Different motor constructions may have different noise propagation frequency signatures.
- noise signatures may be changed by specific installations and field applications.
- an object of the present invention is to create an induction motor noise reduction system capable of dampening windage noise propagating from motor cooling vents that does not unduly restrict cooling airflow to the motor.
- Another object of the present invention is to create an induction motor noise reduction system capable of being tuned to dampen windage noise propagating from motor cooling vents of motors having differing noise propagation properties due to their specific construction traits or installation application.
- the induction motor windage noise damping systems and methods of the present invention that provide for tunable symmetrical or asymmetrical arrays of baffles in a damping duct having a proximal end that is coupled to the motor in communication with a motor cooling vent and a distal end for communication with ambient air.
- the baffle arrays are constructed of generally parallel baffles. In the baffle array, baffle thickness, adjacent baffle lateral spacing and inset from one of the duct openings are chosen to restrict distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies in this way, the damping duct is “tunable” to dampen specific noise frequencies of interest in different motor constructions and/or different specific motor field applications/installations.
- the damping duct baffle array may be selectively pre-configured during construction to meet the needs of a specific application. In other embodiments the baffle array may be configured or modified in the field to meet the specific noise attenuation needs of a particular field application.
- the present invention features an induction motor windage noise damping system, comprising a motor having a housing, a cooling vent formed in the housing, a rotating shaft and rotor within the housing generating windage noise, and a cooling airflow path defined within the housing that is in communication with the cooling vent.
- the present invention has a duct having proximal and distal ends defining respective openings and a duct airflow path there between. The proximal end opening is in communication with the cooling vent, and the distal end opening is for communication with ambient air.
- a plurality of baffles are oriented in an array in the duct.
- a plurality of first baffles are in the duct, having a first thickness
- a plurality of second baffles are in the duct, having a second thickness.
- the first and second baffles are oriented in an generally parallel mutually spaced array relative to each other and the duct airflow path.
- Dimensions for baffle array symmetry or asymmetry, parallel spacing, baffle thickness and baffle inset from the proximal and/or distal opening are chosen to restrict, distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies.
- the damping duct of the present invention may be factory or repair shop installed on an induction, motor, as part of a motor/duct packaged system.
- the duct may provided alone as part of an induction motor damping system that is installed in the field or factory by a motor manufacturer or motor maintenance and repair facility.
- the present invention noise damping duct is provided to a customer without a motor.
- the present invention also provides a method for damping windage noise in an induction motor having a housing, a cooling vent formed in the housing, a rotating shaft and rotor within the housing generating windage noise, and a cooling airflow path defined within the housing that is in communication with the cooling vent.
- This method of the present invention is performed by providing a duct having proximal and distal ends defining respective openings and a duct airflow path there between, the proximal end opening for coupling to an induction motor and communication with a cooling vent thereof, and the distal end opening for communication with ambient air.
- This method is further performed by providing a plurality of baffles that are oriented in an array in the duct.
- the baffle array so provided includes a plurality of first baffles in the duct, having a first thickness; and a plurality of second baffles in the duct, having a second thickness.
- the first and second baffles are selectively oriented in an generally parallel mutually spaced array relative to each other and the duct airflow path.
- Dimensions for baffle array symmetry or asymmetry, parallel spacing, baffle thickness and baffle inset from the proximal and/or distal opening are chosen to restrict distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies, yet provide for adequate cooling airflow through the damping duct.
- FIGS. 1 and 1A are schematic perspective views of an induction motor noise damping system of the present invention, including damping ducts each having an array of baffles;
- FIG. 2 is a sectional plan view of the duct of FIG. 1A taken along 2 - 2 thereof;
- FIG. 3 is a sectional plan view of duct of FIG. 1A taken along 2 - 2 thereof, showing varied spacing between baffles selected to attenuate different noise frequency wavelengths ⁇ 1-4 ;
- FIG. 4 is a cutaway perspective view of one embodiment of the noise attenuation system duct of the present invention for orienting baffles in a selected array through the use of spacer plates;
- FIGS. 5 and 6 show an alternate embodiment for orienting baffles in a selected array through the use of formed corrugated channels formed in the duct;
- FIGS. 7 and 8 show an alternate embodiment for orienting baffles in a selected array through the use of fabricated C channels affixed within the duct;
- FIGS. 9 and 9A show in a schematic perspective view an alternate embodiment of the present invention using a circular baffle array having cylindrical baffles of different width, lateral spacing between cylindrical baffles and axial offset relative to the duct distal end;
- FIG. 10 is a perspective view of an exemplary baffle
- FIG. 11 is a sectional plan view of the baffle of FIG. 10 taken along 11 - 11 thereof.
- teachings of the present invention can be readily utilized in induction motor windage noise damping systems that can be selectively tuned to dampen noise frequencies of interest by varying a baffle array within a cooling duct that is coupled to a motor cooling vent.
- the systems and methods of the present invention can be installed on motors in the factory before deploying them to field locations, or they can be added to motors after they have been deployed.
- FIGS. 1 and 1A show the noise damping system of the present invention installed on an induction motor 20 of known design.
- Motor 20 is shown schematically, and includes a motor housing 22 with frame and related cooling air flow shrouding.
- Rotor 23 rotates on bearings within the housing, generating windage noise that propagates along the cooling airflow path A. Windage noise emanates from the motor housing 22 through cooling vent inlet 24 and outlet 25 .
- cooling vent inlet 24 and outlet 25 For simplicity in describing and showing an embodiment of the present invention, a single cooling vent inlet 24 , outlet 26 and cooling airflow path A are shown in FIG. 1 .
- induction motors often incorporate a plurality of cooling vents and cooling airflow paths.
- the present invention includes one or more noise damping ducts 30 each respectively having a proximal end opening 32 coupled to and in communication with one or more cooling vents 24 or 26 and a distal end opening 34 in communication with ambient air.
- one duct 30 is coupled to one or more inlet cooling vents 24 and another duct 30 is coupled to one or more outlet cooling vents 26 .
- a cooling airflow path A enters duct 30 coupled to the inlet cooling vent 24 , where it transfers heat from the motor housing interior, in turn exits the outlet cooling vent 26 and thereafter is exhausted from duct 30 .
- the ducts 30 of the present invention can be coupled to either or both of inlet cooling vents 24 or outlet cooling vents 26 .
- duct 30 has a top wall 35 , bottom wall 36 and side walls 37 , 38 that form a passage for cooling airflow between its proximal 32 and distal 34 ends.
- the duct 30 supports a plurality of baffles 40 , 42 , 44 that oriented in an generally parallel mutually spaced array relative to each other and the duct cooling airflow path A.
- Dimensions for baffle array parallel spacing, baffle thickness and baffle inset from one or both of the proximal and distal openings are chosen to restrict distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies.
- a plurality of first baffles 40 are rectangular cross-section flat plates or fabricated thin wall boxes having a width or thickness that are inset dimension d 0 from the distal end 34 of duct 30 .
- a plurality of second baffles 42 are also of rectangular cross-section, having a width or thickness W B , that are inset dimension d 1 from the distal end 34 of duct 30 .
- a plurality of third baffles 44 are also of rectangular cross-section, having a width or thickness W C , that are inset dimension d 2 from the distal end 34 of duct 30 .
- Baffles 40 , 42 and 44 are schematically depicted as boxes having a rectangular cross-section, and may be constructed as shown in. FIGS. 10 and 11 , described in greater detail herein. While in this symmetrical baffle array embodiment three widths of baffles are shown with lateral spacing relative to each other and varying insets from the duct 30 distal end, those skilled in the are may choose to construct ducts with symmetrical, or asymmetrical arrays having less than or more than three baffle widths, and employing different patterns of inset and lateral spacing to meet the noise attenuation requirements of different motor designs and applications.
- FIG. 3 depicts how varying combinations of baffle 40 , 42 and 44 lateral spacing, plate thickness/width and inset orientation effectively vary two dimensional air gap distance between adjacent baffles.
- corresponding wavelengths vary between 0.001-5.5 inches (0.028-140 mm).
- Baffles 40 , 42 , 44 may be constructed with width/thickness between 2-8 inches (50-200 mm).
- Baffle inset and lateral spacing is varied in the baffle array so that the two dimensional air gap distance between adjacent baffles varies between 0.5-5.5 inches (13-140 mm). Spacing at the wider distance between most of the adjacent baffles assures adequate cooling air flow A through the duct 30 , for needed motor 20 cooling while attenuating lower frequency noise. Some of the baffles are spaced at more relatively narrower distances to attenuate higher frequency noise. As depicted in FIG.
- the array of baffles 40 , 42 , 44 creates different two dimensional air gap distances ⁇ 1 /3, ⁇ 2 /3, ⁇ 3 /3 and ⁇ 4 /3, each capable of attenuating that corresponding wavelength/frequency as well as lower frequencies having longer wavelengths than the air gap distances.
- the present invention allows one skilled in the art to custom tune noise damping frequencies for different constructions of motors and their applications. Tuning is accomplished easily by varying the baffle array orientation baffle width, lateral spacing and inset from one of the ends of the duct, in order to achieve desired two dimensional air gap spacing between adjacent baffles needed to attenuate a desired noise frequency/wavelength. Custom tuning may be accomplished by varying the duct 30 baffle 40 , 42 , 44 array during duct manufacture or in the field.
- baffle arrays in the duct 30 may be varied through use of spaced baffle channels 50 , 52 , 54 , 56 .
- Baffles 40 , 42 , 44 are selectively oriented in the parallel baffle channels 50 .
- Baffle inset can be varied by sliding the baffle to a desired inset position relative to the duct 30 proximal and/or distal end. If baffles have the same depth dimension between the duct proximal and distal ends, the array baffle inset on one end will have a mirror image baffle array inset on the other end.
- Baffle lateral spacing can be varied by placing them in desired parallel channels 50 . In the embodiment of FIG.
- baffle channels 50 are created by gaps between spacer plates 52 coupled to the duct bottom wall 36 and top wall (not shown).
- baffle channels 54 are integrally formed in the duct 30 bottom wall 36 and top wall (not shown): for example a corrugated sheet metal stamping.
- the baffle channels are C-shaved channels 56 that, are affixed to the duct bottom wall 36 and the top wall (not shown).
- the duct 30 embodiments of FIGS. 1-8 have incorporated generally flat planar polygonal sides between the respective proximal and distal ends.
- the baffles 40 , 42 , 44 are generally rectangular cross-section fabrications in the form of flat planar plates or boxes having a plurality of thicknesses, the construction of which will be described in greater detail below. However, other duct shapes may be utilized.
- the duct 130 has a generally cylindrical profile with a proximal end 132 coupled to a cooling vent and a distal end 134 in communication with ambient air.
- the duct 130 has a generally cylindrical side wall 137 having captured therein generally concentrically arrayed cylindrical baffles, 140 , 142 , 144 of generally annular cross-section, having different annular thicknesses.
- the baffles are retained in relative position by baffle spacers 150 that are affixed to the baffles.
- Baffles 140 , 142 , 144 may be radially spaced at selected distances and inset relative to the duct distal end 132 , so as to achieve desired air gap distance between adjacent baffle.
- baffle symmetry, thickness, spacing and axial inset dimensions may be varied at the discretion of one skilled in the art for particular applications.
- FIGS. 10 and 11 show an exemplary fabricated baffle 240 embodiment, that incorporates known sound damping resilient, material such as sheet foam or injected self-expanding foam.
- Baffle 240 has a fabricated perimeter frame 242 that captures opposed sheets of screen 244 on the large sides of the box-shaped structure. Screen 244 provides additional structural integrity to the baffle 240 as well as shielding from potential impact damage that might be potentially caused by airborne debris. Captured within the baffle 240 perimeter frame 242 and screens 244 is a layer of sound damping foam material 246 .
- the foam 246 may comprise a plurality of layers of sheet foam 246 A, 246 B, and 246 C, that may have distinct sound deadening properties, for example attenuation of different frequency ranges.
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Abstract
Description
- 1. Field of the Invention
- The invention relates to noise reduction systems for induction, motors, and more particularly baffled ducts that may be fitted to motor cooling vents in order to dampen windage noise propagation caused by rotating motor shafts and rotors.
- 2. Description of the Prior Art
- Operating induction motors generate windage noise, caused by the rotating shaft, rotor and related rotating hardware. The windage noise propagates through motor cooling airflow paths that provide a heat transfer path out of the motor housing, including any external shrouds or other motor enclosures, via housing cooling vents. While the motor housing frame, external shrouds and other enclosures absorb or deaden some windage noise, the housing cooling vents enable noise propagation directly to surrounding ambient air. It is desirable to minimize noise exposure to workers who are located near operating motors, especially in the frequency range of 400-4000 Hz that has a greater impact on human hearing than higher or lower frequencies.
- Known ways to minimize windage noise propagation from induction motors have included sound-deadening shrouds or other enclosures that surround the motor and become part of the motor housing. However, it is impractical to shroud larger motors of greater than 1000 horsepower due to their large size. In another known solution, motor housing cooling vents have been coupled to sound dampening ducts having generally parallel planar baffles of identical thickness and lateral spacing that are oriented parallel to the duct cooling airflow path. Lateral spacing of adjacent baffle plates less than the sound propagation wavelength of a given windage noise propagation frequency dampens the noise. While such identical baffle constructions dampen some relevant low frequency (large wavelength) noise, such known constructions do not provide noise dampening over a broad spectrum of noise frequencies. If such known baffle duct construction is modified to decrease spacing between baffles so as to dampen the relatively shorter wavelength of higher noise frequencies, overall cooling airflow performance of the cooling vent decreases to an unacceptable performance level. For example, adjacent baffle spacing of 5.5 inches (140 mm) is sufficient to dampen a 400 Hz noise frequency. Such relatively wide adjacent baffle spacing provides for sufficient air flow rate- and volume into the motor cooling vent. However, a 4000 Hz noise frequency may require baffle parallel spacing of only 0.001 inch. (0.028 mm) to dampen sufficiently that frequency. Laterally spacing all baffles with a gap of 0.001 inch would unduly restrict air flow into the motor cooling vent. Generally one skilled in the art would prefer a minimum baffle lateral spacing of no less than 0.5 inch (13 mm) to allow sufficient cooling air flow. Therefore uniformly spaced baffle dampers potentially sacrifice higher frequency noise attenuation when their shorter wavelengths pass between baffles set at the minimum baffle lateral spacing.
- Also, known identical uniform baffle construction and spacing damping ducts provide a single solution for all applications, whereas different applications might benefit from baffle ducts constructed to meet the noise damping needs of a specific motor design or application for a motor design. Different motor constructions may have different noise propagation frequency signatures. Furthermore noise signatures may be changed by specific installations and field applications.
- Thus, a need exists in the art for an induction motor noise reduction system capable of dampening a broad spectrum of windage noise frequencies propagating from motor cooling vents that does not unduly restrict cooling airflow to the motor.
- Another need exists in the art for an induction motor noise reduction system capable of being tuned to dampen windage noise propagating from motor cooling vents of motors having differing noise propagation properties due to their specific construction traits or installation application.
- SUMMARY OF THE INVENTION
- Accordingly, an object of the present invention is to create an induction motor noise reduction system capable of dampening windage noise propagating from motor cooling vents that does not unduly restrict cooling airflow to the motor.
- Another object of the present invention is to create an induction motor noise reduction system capable of being tuned to dampen windage noise propagating from motor cooling vents of motors having differing noise propagation properties due to their specific construction traits or installation application.
- These and other objects are achieved by the induction motor windage noise damping systems and methods of the present invention that provide for tunable symmetrical or asymmetrical arrays of baffles in a damping duct having a proximal end that is coupled to the motor in communication with a motor cooling vent and a distal end for communication with ambient air. The baffle arrays are constructed of generally parallel baffles. In the baffle array, baffle thickness, adjacent baffle lateral spacing and inset from one of the duct openings are chosen to restrict distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies in this way, the damping duct is “tunable” to dampen specific noise frequencies of interest in different motor constructions and/or different specific motor field applications/installations. The damping duct baffle array may be selectively pre-configured during construction to meet the needs of a specific application. In other embodiments the baffle array may be configured or modified in the field to meet the specific noise attenuation needs of a particular field application.
- The present invention features an induction motor windage noise damping system, comprising a motor having a housing, a cooling vent formed in the housing, a rotating shaft and rotor within the housing generating windage noise, and a cooling airflow path defined within the housing that is in communication with the cooling vent. The present invention has a duct having proximal and distal ends defining respective openings and a duct airflow path there between. The proximal end opening is in communication with the cooling vent, and the distal end opening is for communication with ambient air. A plurality of baffles are oriented in an array in the duct. In some embodiments, a plurality of first baffles are in the duct, having a first thickness, and a plurality of second baffles are in the duct, having a second thickness. In such embodiments, the first and second baffles are oriented in an generally parallel mutually spaced array relative to each other and the duct airflow path. Dimensions for baffle array symmetry or asymmetry, parallel spacing, baffle thickness and baffle inset from the proximal and/or distal opening are chosen to restrict, distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies. The damping duct of the present invention may be factory or repair shop installed on an induction, motor, as part of a motor/duct packaged system.
- Alternatively, the duct may provided alone as part of an induction motor damping system that is installed in the field or factory by a motor manufacturer or motor maintenance and repair facility. For such applications, the present invention noise damping duct is provided to a customer without a motor.
- The present invention also provides a method for damping windage noise in an induction motor having a housing, a cooling vent formed in the housing, a rotating shaft and rotor within the housing generating windage noise, and a cooling airflow path defined within the housing that is in communication with the cooling vent. This method of the present invention is performed by providing a duct having proximal and distal ends defining respective openings and a duct airflow path there between, the proximal end opening for coupling to an induction motor and communication with a cooling vent thereof, and the distal end opening for communication with ambient air. This method is further performed by providing a plurality of baffles that are oriented in an array in the duct. In some embodiments the baffle array so provided includes a plurality of first baffles in the duct, having a first thickness; and a plurality of second baffles in the duct, having a second thickness. In such embodiments, the first and second baffles are selectively oriented in an generally parallel mutually spaced array relative to each other and the duct airflow path. Dimensions for baffle array symmetry or asymmetry, parallel spacing, baffle thickness and baffle inset from the proximal and/or distal opening are chosen to restrict distance between adjacent baffles to less than a wavelength of windage noise at selected propagation frequencies, yet provide for adequate cooling airflow through the damping duct.
- The objects and features of the present invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art.
- The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
-
FIGS. 1 and 1A are schematic perspective views of an induction motor noise damping system of the present invention, including damping ducts each having an array of baffles; -
FIG. 2 is a sectional plan view of the duct ofFIG. 1A taken along 2-2 thereof; -
FIG. 3 is a sectional plan view of duct ofFIG. 1A taken along 2-2 thereof, showing varied spacing between baffles selected to attenuate different noise frequency wavelengths λ1-4; -
FIG. 4 is a cutaway perspective view of one embodiment of the noise attenuation system duct of the present invention for orienting baffles in a selected array through the use of spacer plates; -
FIGS. 5 and 6 show an alternate embodiment for orienting baffles in a selected array through the use of formed corrugated channels formed in the duct; -
FIGS. 7 and 8 show an alternate embodiment for orienting baffles in a selected array through the use of fabricated C channels affixed within the duct; -
FIGS. 9 and 9A show in a schematic perspective view an alternate embodiment of the present invention using a circular baffle array having cylindrical baffles of different width, lateral spacing between cylindrical baffles and axial offset relative to the duct distal end; -
FIG. 10 is a perspective view of an exemplary baffle; and -
FIG. 11 is a sectional plan view of the baffle ofFIG. 10 taken along 11-11 thereof. - To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
- After considering the following description, those skilled in the art will clearly realize that the teachings of the present invention can be readily utilized in induction motor windage noise damping systems that can be selectively tuned to dampen noise frequencies of interest by varying a baffle array within a cooling duct that is coupled to a motor cooling vent. The systems and methods of the present invention can be installed on motors in the factory before deploying them to field locations, or they can be added to motors after they have been deployed.
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FIGS. 1 and 1A show the noise damping system of the present invention installed on aninduction motor 20 of known design.Motor 20 is shown schematically, and includes amotor housing 22 with frame and related cooling air flow shrouding.Rotor 23 rotates on bearings within the housing, generating windage noise that propagates along the cooling airflow path A. Windage noise emanates from themotor housing 22 through coolingvent inlet 24 and outlet 25. For simplicity in describing and showing an embodiment of the present invention, a singlecooling vent inlet 24,outlet 26 and cooling airflow path A are shown inFIG. 1 . As those skilled in the art can appreciate, induction motors often incorporate a plurality of cooling vents and cooling airflow paths. - The present invention includes one or more
noise damping ducts 30 each respectively having aproximal end opening 32 coupled to and in communication with one or more cooling vents 24 or 26 and a distal end opening 34 in communication with ambient air. As shown inFIG. 1 oneduct 30 is coupled to one or more inlet cooling vents 24 and anotherduct 30 is coupled to one or more outlet cooling vents 26. A cooling airflow path A entersduct 30 coupled to theinlet cooling vent 24, where it transfers heat from the motor housing interior, in turn exits theoutlet cooling vent 26 and thereafter is exhausted fromduct 30. Theducts 30 of the present invention can be coupled to either or both of inlet cooling vents 24 or outlet cooling vents 26. - Referring to
FIGS. 1 , 1A and 2,duct 30 has atop wall 35,bottom wall 36 andside walls duct 30 supports a plurality ofbaffles - In the embodiment of
FIGS. 1 , 1A and 2, a plurality offirst baffles 40 are rectangular cross-section flat plates or fabricated thin wall boxes having a width or thickness that are inset dimension d0 from thedistal end 34 ofduct 30. A plurality ofsecond baffles 42 are also of rectangular cross-section, having a width or thickness WB, that are inset dimension d1 from thedistal end 34 ofduct 30. Similarly, a plurality ofthird baffles 44 are also of rectangular cross-section, having a width or thickness WC, that are inset dimension d2 from thedistal end 34 ofduct 30. Baffles 40, 42 and 44 are schematically depicted as boxes having a rectangular cross-section, and may be constructed as shown in.FIGS. 10 and 11 , described in greater detail herein. While in this symmetrical baffle array embodiment three widths of baffles are shown with lateral spacing relative to each other and varying insets from theduct 30 distal end, those skilled in the are may choose to construct ducts with symmetrical, or asymmetrical arrays having less than or more than three baffle widths, and employing different patterns of inset and lateral spacing to meet the noise attenuation requirements of different motor designs and applications. - The schematic view of
FIG. 3 depicts how varying combinations ofbaffle duct 30, for neededmotor 20 cooling while attenuating lower frequency noise. Some of the baffles are spaced at more relatively narrower distances to attenuate higher frequency noise. As depicted inFIG. 3 , the array ofbaffles - The present invention, allows one skilled in the art to custom tune noise damping frequencies for different constructions of motors and their applications. Tuning is accomplished easily by varying the baffle array orientation baffle width, lateral spacing and inset from one of the ends of the duct, in order to achieve desired two dimensional air gap spacing between adjacent baffles needed to attenuate a desired noise frequency/wavelength. Custom tuning may be accomplished by varying the
duct 30baffle - As shown in
FIGS. 4-8 , baffle arrays in theduct 30 may be varied through use of spacedbaffle channels parallel baffle channels 50. Baffle inset can be varied by sliding the baffle to a desired inset position relative to theduct 30 proximal and/or distal end. If baffles have the same depth dimension between the duct proximal and distal ends, the array baffle inset on one end will have a mirror image baffle array inset on the other end. Baffle lateral spacing can be varied by placing them in desiredparallel channels 50. In the embodiment ofFIG. 4 baffle channels 50 are created by gaps betweenspacer plates 52 coupled to theduct bottom wall 36 and top wall (not shown). In the embodiment ofFIGS. 5 and 6 ,baffle channels 54 are integrally formed in theduct 30bottom wall 36 and top wall (not shown): for example a corrugated sheet metal stamping. In the embodiment ofFIGS. 7 and 8 the baffle channels are C-shavedchannels 56 that, are affixed to theduct bottom wall 36 and the top wall (not shown). Once a baffle array is oriented the respective baffles can be coupled to the baffle channels through known affixation means, such as welding, fastening, friction interference fit and gluing. - The
duct 30 embodiments ofFIGS. 1-8 have incorporated generally flat planar polygonal sides between the respective proximal and distal ends. Thebaffles FIGS. 9 and 9A , theduct 130 has a generally cylindrical profile with aproximal end 132 coupled to a cooling vent and adistal end 134 in communication with ambient air. Theduct 130 has a generallycylindrical side wall 137 having captured therein generally concentrically arrayed cylindrical baffles, 140, 142, 144 of generally annular cross-section, having different annular thicknesses. The baffles are retained in relative position bybaffle spacers 150 that are affixed to the baffles.Baffles distal end 132, so as to achieve desired air gap distance between adjacent baffle. As was described with respect to the prior embodiments, baffle symmetry, thickness, spacing and axial inset dimensions may be varied at the discretion of one skilled in the art for particular applications. -
FIGS. 10 and 11 show an exemplary fabricatedbaffle 240 embodiment, that incorporates known sound damping resilient, material such as sheet foam or injected self-expanding foam.Baffle 240 has a fabricatedperimeter frame 242 that captures opposed sheets ofscreen 244 on the large sides of the box-shaped structure.Screen 244 provides additional structural integrity to thebaffle 240 as well as shielding from potential impact damage that might be potentially caused by airborne debris. Captured within thebaffle 240perimeter frame 242 andscreens 244 is a layer of sound dampingfoam material 246. As shown inFIG. 11 thefoam 246 may comprise a plurality of layers ofsheet foam - Although various embodiments which incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings.
Claims (22)
Priority Applications (2)
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US13/031,473 US8240429B1 (en) | 2011-02-21 | 2011-02-21 | System method and devices for windage noise damping in induction motor |
PCT/US2012/025170 WO2012115828A2 (en) | 2011-02-21 | 2012-02-15 | Systems and methods for induction motor windage noise damping |
Applications Claiming Priority (1)
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US13/031,473 US8240429B1 (en) | 2011-02-21 | 2011-02-21 | System method and devices for windage noise damping in induction motor |
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US8240429B1 US8240429B1 (en) | 2012-08-14 |
US20120211300A1 true US20120211300A1 (en) | 2012-08-23 |
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US13/031,473 Active US8240429B1 (en) | 2011-02-21 | 2011-02-21 | System method and devices for windage noise damping in induction motor |
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US (1) | US8240429B1 (en) |
WO (1) | WO2012115828A2 (en) |
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US9580178B2 (en) * | 2015-05-01 | 2017-02-28 | The Boeing Company | Methods and apparatuses for integrated noise control and flow control in an aircraft environmental control system |
PL416695A1 (en) * | 2016-03-30 | 2017-10-09 | Vts Spółka Z Ograniczoną Odpowiedzialnością | Splitter sound attenuator of a ventilation system |
US10722990B2 (en) | 2016-09-15 | 2020-07-28 | General Electric Company | Method for installing and removing modularized silencer baffles |
US10119469B2 (en) * | 2016-09-15 | 2018-11-06 | General Electric Company | Method and apparatus for modularized inlet silencer baffles |
CN108278158B (en) * | 2017-01-06 | 2022-05-13 | 通用电气公司 | System and method for improved inlet muffling baffle |
CN108278157B (en) | 2017-01-06 | 2022-08-02 | 通用电气公司 | System and method for improved inlet silencer baffle |
US10508573B2 (en) * | 2017-04-11 | 2019-12-17 | Caterpillar Inc. | Baffle assembly for a duct |
US11139718B2 (en) | 2017-07-21 | 2021-10-05 | Siemens Industry, Inc. | Electric machine with auxiliary blower mounting arrangement and/or modular exhaust assembly |
GB2568055B (en) * | 2017-11-02 | 2023-02-01 | Brush Elec Machines | Air outlet sound absorber for a rotating electrical machine |
US10411556B1 (en) * | 2018-03-08 | 2019-09-10 | Caterpillar Inc. | Enclosure with inlet and outlet baffles for generator set |
US11411459B2 (en) | 2019-12-06 | 2022-08-09 | Cummins Power Generation Ip, Inc. | Genset enclosure with air deflector assembly |
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US1865677A (en) * | 1929-07-19 | 1932-07-05 | Buffalo Forge Co | Sound deadener |
US2150811A (en) * | 1937-03-10 | 1939-03-14 | Buffalo Pressed Steel Company | Muffler |
US2176615A (en) * | 1937-06-14 | 1939-10-17 | Buffalo Pressed Steel Company | Muffler |
US2299112A (en) * | 1939-10-30 | 1942-10-20 | Robert C Brown Jr | Acoustic filter |
GB1483590A (en) * | 1973-12-27 | 1977-08-24 | Chrysler Uk | Fan assemblies |
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US4316522A (en) * | 1979-11-07 | 1982-02-23 | Industrial Acoustics Company, Inc. | Acoustic filter silencer |
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JP2574573B2 (en) * | 1991-10-18 | 1997-01-22 | 松下精工株式会社 | Ventilation fan |
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-
2011
- 2011-02-21 US US13/031,473 patent/US8240429B1/en active Active
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US8240429B1 (en) | 2012-08-14 |
WO2012115828A2 (en) | 2012-08-30 |
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