U.S. patent application number 11/382466 was filed with the patent office on 2006-11-23 for noise-reduced vacuum appliance.
This patent application is currently assigned to Emerson Electric Co.. Invention is credited to Mark Tomasiak.
Application Number | 20060260866 11/382466 |
Document ID | / |
Family ID | 37441480 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260866 |
Kind Code |
A1 |
Tomasiak; Mark |
November 23, 2006 |
NOISE-REDUCED VACUUM APPLIANCE
Abstract
A vacuum appliance includes a motor having a rotatable shaft. An
air flow generating member is connected to the shaft. The air flow
generated by the rotating member generates noise having a frequency
and corresponding wavelength. An air flow path receives air
generated by the rotating member. The air flow path has first and
second channels, the lengths of which define a predetermined
difference therebetween to cancel the noise. In certain
embodiments, the difference is corresponds to one-half
wavelength.
Inventors: |
Tomasiak; Mark; (St. Louis,
MO) |
Correspondence
Address: |
LOCKE LIDDELL & SAPP LLP;ATTN. DOCKETING
600 TRAVIS #3400
HOUSTON
TX
77002
US
|
Assignee: |
Emerson Electric Co.
St. Louis
MO
|
Family ID: |
37441480 |
Appl. No.: |
11/382466 |
Filed: |
May 9, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60594812 |
May 9, 2005 |
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Current U.S.
Class: |
181/206 |
Current CPC
Class: |
A47L 7/0004 20130101;
A47L 9/0081 20130101 |
Class at
Publication: |
181/206 |
International
Class: |
F01N 1/06 20060101
F01N001/06 |
Claims
1. A vacuum appliance, comprising: a motor having a rotatable
shaft; an air flow generating member connected to the shaft, the
air flow generating member generating noise having a frequency and
corresponding wavelength; and an air flow path receiving air
generated by the air flow generating member, the air flow path
including first and second channels, each channel defining
corresponding first and second lengths, the first and second
lengths defining a predetermined difference therebetween to cancel
the noise.
2. The vacuum appliance of claim 1, wherein the predetermined
difference between the first and second lengths corresponds to
one-half wavelength.
3. The vacuum appliance of claim 1, wherein the air flow generating
member comprises a blower wheel.
4. The vacuum appliance of claim 1, wherein the air flow generating
member comprises a cooling fan.
5. The vacuum appliance of claim 1, wherein the air flow generating
member comprises a commutator of the motor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a non-provisional application of U.S.
Provisional Application No. 60/594,812, filed on May 9, 2005, which
is incorporated by reference.
BACKGROUND
[0002] The present invention relates generally to vacuum
appliances.
[0003] Vacuum appliances are well known. For example, vacuum
appliances that are capable of picking up both wet and dry
material, commonly referred to as wet/dry vacuums or wet/dry vacs,
are often used in workshops and other environments where both wet
and dry debris can accumulate. Wet/dry vacuums conventionally
consist of a collection canister or drum, usually mounted on a
dolly having wheels or casters, and a powerhead within which a
motor and impeller assembly is mounted. The motor and impeller
assembly creates a suction within the drum, such that debris and/or
liquid are drawn into the drum through an air inlet to which a
flexible hose can be attached. A filter within the drum prevents
incoming debris from escaping from the drum while allowing filtered
air to escape.
[0004] A typical wet/dry vacuum motor and blower assembly includes
a motor having a closed-face, multiple-blade blower wheel or
impeller disposed on a drive shaft thereof. The motor and blower
assembly is typically disposed in a collection canister lid
assembly, with the rotating blower wheel disposed within a blower
chamber, sometimes referred to as a collector chamber. The
collector chamber is accessed via an air intake, such that a
suction created by rotation of the impeller within the collector
chamber causes air to be drawn into the air intake.
[0005] A conventional wet/dry vacuum has two air flow systems. A
first air flow system is established for cooling the motor. The
second air flow system is the blower wheel or impeller airflow,
which affects the suction performance of the vacuum (and the
blowing performance, for those vacs which are adaptable or
convertible between and vacuum and a blower).
[0006] A common problem with vacuum cleaners, and especially
wet/dry vacuums, is the excessive and irritating noise generated by
the vacuum cleaner. The vacuum motor itself generates noise, and in
vacuum cleaners having blowing ports, the high-velocity air exiting
the blowing port further creates an especially annoying
high-pitched "whine." While providing a muffler device on the
blowing port and/or adding noise muffling materials inside the
appliance is effective at reducing some noise, other components of
the appliance continue to contribute to noise production.
[0007] The present application addresses shortcomings associated
with the prior art.
SUMMARY
[0008] In accordance with certain teachings of the present
disclosure, a vacuum appliance such as a wet dry vacuum includes a
motor having a rotatable shaft. An air flow generating member, such
as a blower wheel and/or cooling fan, is connected to the shaft.
The air flow generated by the rotating member generates noise
having a frequency and corresponding wavelength. In motors having a
commutator, such as a universal motor, the rotating commutator
further generates air flow and corresponding noise. An air flow
path receives air generated by the rotating member. The air flow
path has first and second channels, the lengths of which define a
predetermined difference therebetween to cancel the noise. In
certain embodiments, the difference is corresponds to one-half
wavelength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other objects and advantages of the invention will become
apparent upon reading the following detailed description and upon
reference to the drawings in which:
[0010] FIG. 1 is a block diagram conceptually illustrating portions
of a vacuum appliance in accordance with certain teachings of the
present disclosure.
[0011] FIGS. 2A-2D are graphs illustrating passive noise
cancellation effectiveness.
[0012] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION
[0013] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0014] FIG. 1 is a block diagram conceptually illustrating portions
of a vacuum appliance 100 in accordance with certain teachings of
the present disclosure. The vacuum 100 includes a collection
canister or drum 110 and a powerhead 112 within which a motor and
impeller assembly is mounted. The powerhead 112 creates a suction
within the drum 110, such that debris and/or liquid are drawn into
the drum 110 through an air inlet 114 to which a flexible hose can
be attached. A filter 120 within the drum prevents incoming debris
from escaping from the drum 110 while allowing filtered air to
escape through an air exhaust port (not shown).
[0015] The powerhead 112 includes a motor 130 having a blower wheel
or impeller 132 disposed on a drive shaft thereof, with the
rotating blower wheel disposed within a blower chamber 134,
sometimes referred to as a collector chamber. The motor 130
includes a cooling fan 136. A universal motor is used in exemplary
vacuum systems. The appliance 100 has two air flow systems. One is
established for cooling the motor 130 with the cooling fan 136, and
the other is the blower wheel 132 or impeller airflow which
generates the suction inside the drum 110.
[0016] As noted in the background section herein, it is desirable
to continue to reduce noise generated by vacuum appliances such as
wet/dry vacuums. Sources of noise generated by the powerhead
include the blower wheel 132, the motor's commutator/brush
interface, and the cooling fan 136. By manipulating passageways for
the motor cooling air 150 and the motor exhaust air 152 such that
the length of the passageway corresponds to wavelengths of noise
frequencies to be eliminated, the overall noise level of the
appliance is reduced without the addition of noise-reducing
hardware. The passageways 150,152 are created so that the
wavelengths are 180 degrees out of phase for the particular
frequency to be eliminated.
[0017] In one exemplary implementation, dual air channels were
provided in a wet/dry vacuum for each of three noise sources, with
corresponding frequency (cycles/second) and wavelength
(inches):
[0018] Blower wheel: 2,333,3 cycles/sec; 5.80 inches
[0019] Cooling Fan: 3,666,7 cycles/sec; 3.69 inches
[0020] Commutator: 7,333.3 cycles/sec; 1.85 inches.
[0021] The channels of the dual air channels corresponding to each
of these noise sources is one-half wavelength different in length,
so one channel "cancels" the noise of the other channel.
[0022] FIGS. 2A-2D are graphs illustrating motor frequency,
frequency with commutator cancellation, frequency with cooling fan
cancellation and frequency with both commutator and cooling fan
cancellation, respectively. As shown in the graphs, substantial
noise reduction is achieved with both commutator and cooling fan
cancellation.
[0023] In tests where the difference between the two flow length
paths for the various air channels was varied, the noise level was
minimal when the difference between flow length channels was
one-half wavelength. In contrast, the noise level was maximum when
the difference between the flow length channels was one-quarter
wavelength, because at this difference, the noise is additive and
not canceling.
[0024] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below. It is therefore
evident that the particular embodiments disclosed above may be
altered or modified and all such variations are considered within
the scope and spirit of the invention. Accordingly, the protection
sought herein is as set forth in the claims below.
* * * * *