U.S. patent application number 14/776783 was filed with the patent office on 2016-02-18 for portable positive pressure apparatus and method for the attenuating the noise emitted therefrom.
This patent application is currently assigned to HUMAN DESIGN MEDICAL, LLC. The applicant listed for this patent is HUMAN DESIGN MEDICAL, LLC, Karl R. LEINSING, Kevin Scott LIBRETT. Invention is credited to Karl R Leinsing, Kevin Scott Librett.
Application Number | 20160045693 14/776783 |
Document ID | / |
Family ID | 51022400 |
Filed Date | 2016-02-18 |
United States Patent
Application |
20160045693 |
Kind Code |
A1 |
Librett; Kevin Scott ; et
al. |
February 18, 2016 |
PORTABLE POSITIVE PRESSURE APPARATUS AND METHOD FOR THE ATTENUATING
THE NOISE EMITTED THEREFROM
Abstract
The systems, apparatus and methods described herein provide a
quiet, light-weight, and portable system and apparatus for
providing positive air pressure to a patient. The application
discloses a CPAP apparatus (100, 300, 400, 500, 600, 700, 900)
comprising: a housing (180, 380, 381, 780, 784, 980) defining a
first acoustic chamber (402, 502, 602, 930) with a first inlet port
(412, 512, 612, 613, 910), and a second acoustic chamber (414, 514,
614, 934) with a blower unit (140, 416, 516, 616, 740, 940) and a
second inlet port (422, 507, 622, 917) extending from the first to
the second chamber. The CPAP apparatus can be portable. A system
can comprise the apparatus comprising an adapter (160, 360, 760,
960) in communication with the blower unit and extending outward
from the apparatus, and a detachable patient interface system (165,
365, 965). The apparatus can include alternatively a single
acoustic chamber (130, 230, 730) with an inlet port (110, 710) most
of whose length is within the acoustic chamber, and an outlet port
(139, 739). The blower unit can be vibrationally isolated. The
dimensions of inlet ports and acoustic chambers may be
proportionally related, in particular defining an acoustic low-pass
filter. The application discloses a method for reducing noise in a
portable CPAP device with first and second acoustic chambers,
including routing the flow of air through the device, wherein the
first inlet is sealed from and passes through the second chamber
into the first acoustic chamber, and the flow of air is routed
through an outlet port sealed from and passing through the first
chamber.
Inventors: |
Librett; Kevin Scott;
(Watertown, MA) ; Leinsing; Karl R; (Dover,
NH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LIBRETT; Kevin Scott
LEINSING; Karl R.
HUMAN DESIGN MEDICAL, LLC |
Watertown
Dover
Charlottesville |
MA
NH
VA |
US
US
US |
|
|
Assignee: |
HUMAN DESIGN MEDICAL, LLC
Allston
MA
|
Family ID: |
51022400 |
Appl. No.: |
14/776783 |
Filed: |
March 17, 2014 |
PCT Filed: |
March 17, 2014 |
PCT NO: |
PCT/US14/30640 |
371 Date: |
September 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61798367 |
Mar 15, 2013 |
|
|
|
61798541 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
128/204.18 ;
29/428 |
Current CPC
Class: |
A61M 16/0069 20140204;
F04D 29/4226 20130101; A61M 16/0063 20140204; F04D 29/663 20130101;
F04D 29/664 20130101; F05D 2250/51 20130101; A61M 16/022 20170801;
A61M 2207/00 20130101; A61M 16/0858 20140204; G10K 11/04 20130101;
A61M 16/0816 20130101; G10K 11/161 20130101; F04D 29/4213 20130101;
A61M 16/107 20140204; Y10T 29/49826 20150115; A61M 2205/75
20130101; A61M 2205/50 20130101; A61M 2205/8206 20130101; A61M
2205/505 20130101; A61M 2205/42 20130101; A61M 2205/3355 20130101;
F05D 2260/96 20130101; A61M 16/0066 20130101; A61M 2205/502
20130101; F04D 29/665 20130101; A61M 2016/0027 20130101; A61M
16/0875 20130101 |
International
Class: |
A61M 16/00 20060101
A61M016/00; A61M 16/08 20060101 A61M016/08; A61M 16/06 20060101
A61M016/06 |
Claims
1. A portable CPAP apparatus, comprising: a housing, wherein the
housing defines a first and a second acoustic chamber, the first
acoustic chamber having a volume and a first inlet port, the first
inlet port defining a length and cross-sectional area that is
proportionally related to the volume of the first chamber and the
second acoustic chamber having a volume and a second inlet port,
wherein the second inlet port extends from the first acoustic
chamber into the second acoustic chamber; and a blower unit that is
disposed within the second acoustic chamber.
2. The apparatus of claim 1, wherein the length and cross-sectional
area of the first inlet port and the volume of the first acoustic
chamber are proportionally related so as to create a low-pass
acoustic filter.
3. The apparatus of claim 1, wherein the combined volume of the
first and second acoustic chambers is less than 360
milliliters.
4. The apparatus of claim 1, wherein the first inlet port further
comprises a first intake tube having a diameter ranging from 0.25
inches to 0.75 inches and a length ranging from 0.25 inches to 3.5
inches.
5. The apparatus of claim 1, wherein the second inlet port further
comprises a second intake tube having a diameter ranging from 0.25
inches to 0.75 inches and a length ranging from 0.25 inches to 3.5
inches.
6. The apparatus of claim 1, wherein the housing further comprises
an anechoic material disposed therein.
7. The apparatus of claim 1, further comprising an adapter having a
proximal end and a distal end, wherein the proximal end is in
communication with the blower unit through a blower outlet tube and
the distal end extending outward from the apparatus.
8. The apparatus of claim 7, wherein the blower outlet tube defines
a sealed air-flow pathway between the blower unit and the
adapter.
9. The apparatus of claim 1, wherein the housing further defines a
hose port configured to receive a patient interface system.
10. The apparatus of claim 1, wherein the housing further comprises
at least one user interface button.
11. The apparatus of claim 1, wherein the housing further comprises
a digital display.
12. The apparatus of claim 1, wherein the housing further comprises
an acoustically invisible cover positioned over the inlet port of
the first acoustic chamber.
13. The apparatus of claim 1, wherein the first inlet port
comprises an intake tube which passes through the second chamber
into the first chamber and is sealed from the second chamber.
14. The apparatus of claim 13, further comprising an outlet tube
extending from the blower in the second acoustic chamber and
traversing through the first acoustic chamber and through the
housing wall.
15. The apparatus of claim 1, wherein the cross-sectional area and
length of the first inlet port is related to the noise generated by
the blower, wherein the overall acoustic reduction is balanced with
any increase in blower noise generated.
16. The apparatus of claim 1, wherein the volume of the second
acoustic chamber is greater than the volume of the first acoustic
chamber.
17. A system for providing continuous positive air pressure to a
patient, comprising: a continuous positive air pressure apparatus
having, a housing, wherein the housing defines a first and a second
acoustic chamber, the first acoustic chamber having a volume and a
first inlet port, the first inlet port defining a length and
cross-sectional area that is proportionally related to the volume
of the first chamber and the second acoustic chamber having a
volume and a second inlet port; a blower unit that is disposed
within the single acoustic chamber,; an adapter, having a proximal
end and a distal end, wherein the proximal end is in communication
with the blower unit through a blower outlet tube and the distal
end extending outward from the apparatus; and a patient interface
system detachably connected to the distal end of the adapter.
18. The system of claim 17, further comprising a pressure port in
fluid communication with the adapter.
19. The system of claim 18, further comprising a sensor disposed
within the housing that is in fluid communication with the pressure
port.
20. The system of claim 17, wherein the blower unit is
vibrationally isolated from the housing.
21. The system of claim 17, wherein the housing further comprises
an acoustically invisible cover positioned over the inlet port of
the acoustic chamber that does not increase the dBA of the system
by more than 3 dBA.
22. The system of claim 21, wherein a portion of the acoustically
invisible cover is comprised of a wire mesh material.
23. A method for reducing the amount of noise released from a
portable CPAP device while in operation, comprising: providing a
housing wherein the housing defines a first and a second acoustic
chamber, routing the flow of air through a first inlet that is
sealed from and passes through the second acoustic chamber into the
first acoustic chamber; routing the flow of air from the first
acoustic chamber into the second acoustic through a second inlet
port, wherein a blower is mounted within the second acoustic
chamber; and routing the flow of air from the second acoustic
chamber through an outlet port that is sealed from and passes
through the first chamber.
24. The method of claim 23, further comprising the step of
balancing an acoustic low pass filter design based on the
proportionality of a length and cross-sectional area of the first
inlet port with the volume of the first acoustic chamber with any
increase in noise generated by the blower positioned in the second
acoustic chamber caused by additional work required to maintain a
desired amount of air flow.
25. The method of claim 23, further comprising positioning the
opening of the inlet port on the opposite end of the housing
wherein the opening of the outlet port is formed.
26. A positive air pressure apparatus, comprising: a housing,
wherein the housing defines an acoustic chamber having a volume, an
inlet port, and an outlet port, wherein the inlet port extends
through an exterior wall of the housing and has a length and
cross-sectional area proportionally defined by the volume of the
acoustic chamber, and wherein a majority of the length of the inlet
port is disposed inside the acoustic chamber; and a blower unit
disposed within the acoustic chamber, wherein the blower unit is
vibrationally isolated from the housing.
27. The apparatus of claim 26, wherein the inlet port defines a
circuitous path having at least one bend.
28. The apparatus of claim 26, further comprising a noise
attenuating unit positioned near an opening of the inlet port into
the volume of the acoustic chamber, such that at least some
acoustic noise generated by the blower is attenuated by the noise
attenuating unit.
29. The apparatus of claim 28, wherein the noise attenuating unit
is angled relative to the opening of the inlet port into the
acoustic chamber.
30. A method for reducing making a portable cpap system comprising
the steps of: determining the desired size of the cpap system;
determining the desired airflow and matching the desired airflow
with a blower; forming a first acoustical chamber having an inlet
port and tube that are proportional to the volume of chamber,
wherein a frequency low pass filter is created; and reduce the area
of the inlet port until the noise generated by the blower is no
longer offset by the reduction in area.
Description
COPYRIGHT STATEMENT
[0001] A portion of the disclosure of this patent application
document contains material that is subject to copyright protection
including the drawings. The copyright owner has no objection to the
facsimile reproduction by anyone of the patent document or the
patent disclosure as it appears in the Patent and Trademark Office
file or records, but otherwise reserves all copyright rights
whatsoever.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to medical devices, and, more
particularly to devices providing positive airway pressure [PAP]
such as continuous positive airway pressure [CPAP] devices,
automatic positive airway pressure devices [APAP], variable
positive airway pressure devices [VPAP], and bi-level positive
airway pressure devices [BPAP].
[0004] 2. Description of the Prior Art
[0005] It is known that applying a CPAP device to a patient may
prevent upper airway occlusion during sleep. CPAP devices have
become the apparatus of choice for the treatment of chronic sleep
apnea, chronic pulmonary obstruction and snoring. Many CPAP
machines are readily available in the marketplace.
[0006] A typical CPAP system generally includes a bedside generator
comprising, a blower unit powered by an electric motor. The blower
unit, the motor, and associated controls are usually encased
together within the bedside generator. A delivery tube, usually a
flexible plastic tube having a proximal end and a distal end, is
used to deliver pressurized air or other gasses to the patient. The
proximal end of the delivery tube is connected to the bedside
generator and the distal end of the delivery tube is fitted to the
face of a patient. The patient interface may include features that
allow the patient interface to be affixed to the patient and
maintain a proper orientation with respect to the patient.
[0007] Bedside CPAP machines are typically large and heavy. They
are usually plugged into a wall outlet for power or have a large
external battery. The size, weight, and power constraints can
interfere with patients' ability and willingness to use the
machine. For example, these constraints can make it difficult to
utilize the CPAP apparatus in areas away from their bedside or
while traveling. Additionally, these constraints can also prohibit
patients from moving freely during sleep, thereby inducing further
discomfort.
[0008] Furthermore, typical CPAP devices are relatively loud and
can interfere with a patient's sleep or the sleep of other people
nearby. In a typical CPAP device, sound may be propagated from
various locations and actions of the device, such as the flow of
air the flow of air into and out of the device or the operation of
the motor and fan. Because the apparatus is used mainly in a
bedroom or other place having a low ambient noise level to
facilitate sleep, it is important that the blower operates quietly
so as not to disturb the patient or others in close proximity while
they sleep.
[0009] A need therefore exists for PAP devices with size, weight,
and sound characteristics that provide improved usability for
patients.
SUMMARY OF THE INVENTION
[0010] The system and methods described herein provide a CPAP
apparatus that can be held and operated in one hand, is portable,
and is quieter than 30 decibels, quieter than 28 decibels (dBA)
while in operation, quieter than 27 dBA and in some cases quieter
than 26 dBA.
[0011] In an exemplary embodiment, the current application
discloses an CPAP apparatus comprising: dual sealed chambers
connected in series, each having an inlet port that is proportional
in size to its respective chamber; a motor or blower that is placed
within the second chamber, wherein vibrations from the motor or
blower are isolated or substantially isolated from the second
chamber and/or housing; and in some embodiments a foam or other
noise attenuating material may be added to further attenuate the
amount of noise heard by the patient. In some embodiments noise
attenuating units comprised of angled plates, circuitous paths and
other acoustically obstructive and positioned units are
strategically placed inside the acoustic chambers near the
inlets.
[0012] In at least one embodiment, aside from the inlet port and
the blower outlet port, the CPAP apparatus is otherwise
hermetically sealed. In additional embodiments, the blower outlet
port may extend or connect to a patient interface system, which may
include a tube or mask.
[0013] A method for reducing the amount of noise released from a
portable CPAP device while in operation, comprising the steps of
providing a housing wherein the housing defines a first and a
second acoustic chamber, routing the flow of air through a first
inlet port that is sealed from and passes through the second
acoustic chamber into the first acoustic chamber; routing the flow
of air from the first acoustic chamber into the second acoustic
through a second inlet port, wherein a blower is mounted within the
second acoustic chamber; and routing the flow of air from the
second acoustic chamber through and outlet port that is sealed from
and passes through the first chamber.
[0014] The method may further comprise the step of balancing an
acoustic low pass filter design based on the proportionality of a
length and cross-sectional area of the first inlet port with the
volume of the first acoustic chamber against any increase in noise
generated by the blower positioned in the second acoustic chamber
caused by additional work required to maintain a desired amount of
air flow.
[0015] Single acoustic chamber embodiments are also disclosed
herein wherein the majority of the length of the inlet port into
the acoustic chamber is disposed within the chamber and the length
and cross-sectional area of the inlet port are defined by the
volume and length of the acoustic chamber, such that a low pass
acoustic filter is created to balance against any increase in noise
caused by additional work performed by a blower disposed inside the
acoustic chamber.
[0016] In all of the embodiments the blower may also be
vibrationally isolated from the chamber in which it is
disposed.
[0017] These and other embodiments are described in more detail
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing and other objects, aspects, features, and
advantages of the disclosure will become more apparent and better
understood by referring to the following description taken in
conjunction with the accompanying drawings, in which:
[0019] FIG. 1 is a perspective view of the interior of a PAP
apparatus; and
[0020] FIG. 2 illustrates the relationship between the area of an
inlet port and an acoustic chamber for at least one embodiment of a
PAP apparatus;
[0021] FIG. 3A depicts a perspective view of a portable PAP
apparatus; and
[0022] FIG. 3B illustrates a perspective view of a PAP apparatus,
including an adapter portion; and
[0023] FIG. 3C illustrates a system for providing positive air
pressure to a patient; and
[0024] FIG. 4 depicts the interior of a portable PAP apparatus;
and
[0025] FIG. 5 is an illustrative example of a PAP apparatus;
and
[0026] FIG. 6 illustrates the interior of a portable PAP apparatus;
and
[0027] FIGS. 7A-7D depict a PAP apparatus having an internal
pressure sensor; and
[0028] FIGS. 8A-B illustrate a cover for a PAP apparatus; and
[0029] FIG. 9 is a perspective view of the interior of a
multi-chamber PAP apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0030] To provide an overall understanding of the systems, devices,
and methods described herein, certain illustrative embodiments will
be described. Although the embodiments and features described
herein are frequently described for use in connection with CPAP
apparatuses, systems, and methods, it will be understood that all
the components, mechanisms, systems, methods, and other features
outlined below may be combined with one another in any suitable
manner and may be adapted and applied to other PAP apparatuses,
systems, and methods, including, but not limited to, automatic
positive airway pressure devices [APAP], variable positive airway
pressure devices [VPAP], bi-level positive airway pressure devices
[BPAP], and related apparatuses, systems, and methods.
[0031] Bedside CPAP machines are typically large, heavy, and noisy.
The systems and methods described herein are directed towards a
small, quiet, light-weight, and portable CPAP device to overcome
this current limitations and disadvantages. A typical CPAP device
on the market weighs at least 16 ounces or more. The system and
methods described herein may be used to provide a PAP device, such
as a CPAP device, weighing 10 ounces or less.
[0032] FIG. 1 depicts the interior of a PAP apparatus, such as a
CPAP device. CPAP device 100 has a lower housing component 180,
which together with an upper housing component (not shown) defines
a sealed chamber 130. Sealed chamber 130 has an inlet port 110 and
an outlet port 139. A motor or blower 140 is placed within chamber
130. In certain approaches, device 100 includes a pre-intake
chamber 172. Pre-intake chamber 172 may be separated from sealed
chamber 130 by wall 174. Pre-intake chamber 172 serves to prevent
the occlusion of inlet port 110 during use of device 100, and may
also include filter 170.
[0033] In some embodiments, foam or another anechoic material may
be placed within chamber 130 to further attenuate noise produced
during the operation of device 100. The anechoic or noise
attenuating material may be secured at specific locations within
each chamber, such as along the housing (e.g., housing 180), tubes
(e.g., tube 115 and 145), and blower (e.g., blower 140). In certain
embodiments, the lower and/or upper housing components may be lined
with an anechoic or noise attenuating material. In such
embodiments, the anechoic or noise attenuating material may include
foam, rubber, clay, silicon, or any other suitable soft and/or
porous materials.
[0034] In certain approaches, blower 140 is secured to chamber 130
using one or more mount connects 150. In some embodiments, mount
connect 150 may further comprise pivoting cone connectors, circular
donut shaped mount connects, a silicone cradle, or any combination
thereof. For example, mount connect 150 may comprise pivoting cone
connectors that connect the top of blower 140 within chamber 130
and circular donut shaped mount connects that connect the bottom of
blower 140 within chamber 130. In addition to connecting blower 140
to the housing, mount connects 150 may reduce or eliminate transfer
of vibrations from blower 140 to other components of device 100. In
certain embodiments, blower 140 is a brushless air-bearing
motor.
[0035] Device 100 additionally includes connector portion 185 to
couple lower housing 180 and upper housing together, thereby
creating a seal. In the depicted example, connector portions 185
are around the perimeter of the housing. A fastener, such as a
screw, may be used to couple the housing. Additionally or
alternatively, edge 182 of the housing may provide a coupling
and/or sealing mechanism. For example, edge 182 may have a tongue
and groove. Edge 182 may also include a seal, such as santoprene or
silicone.
[0036] In certain embodiments, inlet port 110 includes an intake
tube 115 having a first end 112 through wall 174 and a second end
120 that extends into chamber 130. Intake tube 115 may have either
a constant or varying internal diameter ranging from approximately
0.25 inches to approximately 0.75 inches and may have a length
ranging from approximately 0.25 inches to approximately 3 inches,
although any appropriate diameter and length may be used. The
length and diameter of intake tube 115 affect the overall noise
attenuation of the CPAP device, as will be further discussed below,
for example, in relation to FIG. 2, equation 1, and equation 2.
Accordingly, in some approaches, the dimensions of intake tube 115
are proportionally related to the volume of chamber 130.
[0037] Intake tube 115 may be formed using rigid materials,
flexible materials, or any combination thereof. For example, intake
tube 115 may be formed using a hard plastic. In certain
embodiments, intake tube 115 is composed of flexible
polyvinylchloride (PVC) tubing, silicone tubing, or any other type
of tubing commonly used in the art.
[0038] In certain approaches, outlet port 139 includes outlet tube
145, which extends from blower outlet 137 through the housing. An
adapter 160 may be used to connect blower outlet tube 145 to
patient interface 165. Adapter 160 may be solitary in construction
and configured so that a proximal portion of adapter 160 may be
secured and sealed to the housing of device 100, while a distal
portion of adapter 160 extends outward from device 100.
Additionally or alternatively, adapter 160 may be removably coupled
to the housing components. Lower housing component 180 and the
upper housing component may each include a detent (not pictured)
capable of accepting a portion of the adapter, whereby the two
housing components together form a seal around the circumference of
a portion of the adapter.
[0039] Outlet tube 145 may also vary in length and diameter. The
length of blower outlet tube 145 is long enough to connect to
outlet 137 of blower 140 through outlet port 139. Outlet tube 145
provides a sealed airway between blower 140 and adapter 160 and/or
patient interface system 165. Additionally, depending on the
dimensions of the blower 140, the inner diameter of the outlet tube
145 may vary so long as the diameter is large enough to fit over
and seal with outlet 137, and adapter 160 or patient interface
system 165. Outlet tube 145 may be formed using rigid materials,
flexible materials, or any combination thereof. For example, outlet
tube 145 may be formed using a hard plastic. In certain
embodiments, outlet tube 145 is composed of flexible
polyvinylchloride (PVC) tubing, silicone tubing, or any other type
of tubing commonly used in the art.
[0040] In certain embodiments, pre-intake chamber 172 includes a
filter 170 to clean the air of particulate matter. In certain
embodiments, pre-intake chamber 172 is removable from sealed
chamber 130 and other components of device 100 so that it may be
cleaned, replaced, or adapted for a particular need. For example,
various types of filters may be used for filter 170 depending on a
patient's health. Filter 170 may not be required for all patients,
may be replaceable, or may be cleaned.
[0041] During operation, PAP device 100 creates positive air
pressure through outlet port 139. For example, when patient
interface 165 is attached, PAP device 100 creates positive air
pressure, which can be provided to the patient when the patient
places patient interface 165 at his or her airways (e.g., nose or
mouth). Blower 140 includes intake 135. When blower 140 is powered
on, blower 140 intakes air through intake 135 and pushes out that
air through outlet 137. The reduced pressure at intake 135 causes
air to flow through inlet port 110 into chamber 130, where it then
flows into intake 135 of blower 140, and is pushed by blower 140
through outlet 137, through outlet tube 145, and through outlet
port 139 to thereby provide positive air pressure through outlet
port 139. In certain embodiments, air may be passed through
pre-intake chamber 172, before entering inlet port 110. In certain
approaches, the pressurized air is delivered to a patient through
patient interface 165 at a pressure ranging from approximately 2
centimeters (cm) of water to approximately 40 cm of water above
atmospheric pressure at the point of use, although any appropriate
pressure may be used.
[0042] FIG. 2 illustrates a low-pass acoustic filter system. The
equation below describe the effects modifying each geometrical
section of the filter system has on the system.
T .pi. = ( 1 1 + ( S 1 - S 2 S ) kL ) Equation 1 ##EQU00001##
[0043] In Equation 1, T is the power transmission, also referred to
as the acoustic output, sound level, or noise level; k is the
wavenumber of the sound; S1 is the area of an acoustic chamber
(e.g., chamber 230); L is the length of an acoustic chamber; and S
is the area of an inlet port or tube (e.g., port 220). Thus, if S1
increases in size, L increases in length, or S decreases in area,
then the power transmission T is reduced.
[0044] In accordance with the present disclosure, the area of the
respective acoustic chamber (S1) and the area of its inlet port (S)
may have a proportional relationship. For example, the area of the
chamber may be larger than the area of the inlet port by a factor
of 2. In additional embodiments, S1 may be larger than S by a
factor ranging from a factor of approximately 2 to a factor of
approximately 20 or more. In at least one embodiment, S1 is larger
than S by a factor of about 10. Additionally, the length of L may
be increased wherein the portion of the tube and the acoustic
chamber effectively act as a single chamber, thus decreasing the
amount of noise emanating from the system.
[0045] Referring to FIG. 2, the inlet pathway defined by S is
smaller than the upstream portion of the acoustic chamber. In
accordance with equation 1, when S is reduced relative to S1, then
T or the noise level is attenuated. By increasing L (the length of
the acoustic chamber), the noise may be further attenuated. In
addition, if the inlet pathway is sufficiently long, the effective
length of the acoustic chamber increases from L to L1, thus also
reducing the noise of the system.
[0046] There exists a proportional relationship between the length
of the inlet tube or port and the cross-sectional area of the inlet
port with the volume (and length) of the receiving acoustic
chamber. However increasing the length of the inlet port and
restricting the cross-sectional area of the inlet port causes the
resistance-to-air-flow in the system to increase. This may in turn
cause a blower disposed inside an acoustic chamber to have to work
harder, which may result in an increase in noise generated from the
blower (or motor of the blower). Thus, a balancing and optimization
step is often required when trying to create a sufficiently
portable PAP device that is both quiet and small in size. Equation
2, illustrates this relationship of increasing or modifying the
various dimensions of the inlet port and the effect it has on the
increased motor work and noise.
Resistance of air flow .varies. Length inlet Area inlet .varies.
Motor Work .varies. Motor Noise Equation 2 ##EQU00002##
[0047] Another way of describing this is a smaller inlet diameter
increases air flow resistance, which increases motor noise. Some
practical steps have been incorporated to also position inlet ports
on the PAP device such that they point away from the ears of the
user. For example, in several of the figures the inlet port is on
the opposite end of the outlet port and adapters, which lead to the
tubing that takes air to the mask placed over the user's nose
and/or mouth. In several instances most of the noise escaping the
system leaves through the inlet port.
[0048] Equation 1 can also be used to describe the relationship
between length and noise attenuation in an individual tube. In the
case of a single, individual tube, S1 is equal to S. Accordingly,
the noise output T is reduced when the tube is lengthened (L is
increased). This characteristic is important because the length of
the intake tube (such as intake tube 115) can be used to decrease
the noise of the PAP device (such as device 100 and other systems
and methods described herein). Equation 3 describes the
relationship between the cut-off frequency of the acoustic
filtering and the length and areas of the chamber and tube:
f c = ( Sc .pi. L ( S 1 - S ) ) Equation 3 ##EQU00003##
[0049] In equation 3: f.sub.e is the cutoff frequency; c is the
speed of sound; S1 is the area of the expansion chamber; L is the
length of the tube or chamber; and S is the area of inlet port.
Thus, as L or S1 become larger in value, and/or S becomes smaller,
the cutoff frequency becomes lower and every frequency above the
cutoff frequency is significantly attenuated. In practical terms,
the cutoff frequency f.sub.c can be reduced by increasing the ratio
of S1:S, for example by decreasing the area of the inlet and/or
increasing the area of the acoustic chamber. Additionally,
lengthening the acoustic chamber (increase L) will also reduce the
cutoff frequency.
[0050] FIG. 3A depicts a perspective view of a portable PAP
apparatus 300. Apparatus 300 includes a lower housing component 380
coupled with an upper housing component 381 to form an exterior
enclosure for apparatus 300. Apparatus 300 includes a digital
display 395 and user interface buttons 390 for controlling and
using apparatus 300. For example, a user may be able to turn the
power on and off, adjust pressure settings, set a timer, run system
diagnostic tests, and control or adjust other functions. Display
395 may be any appropriate display, including, but not limited to
an LED or LCD display. Although 1-3 user interface buttons 390 are
depicted in FIG. 3A, any appropriate number of buttons may be used.
In certain approaches, a PAP apparatus, such as apparatus 300, may
include between 1 and 10 user interface buttons. In certain
approaches, user interface buttons are included in display 395. For
example, display 395 may be a capacitive or pressure-sensitive
touch screen display. Further, display 395 may vary in size between
different embodiments. For example, some embodiments may include a
larger display, while other embodiments may include a smaller
display. Display 395 may display data or control functions, such as
pressure levels, time, use time, or other information. Display 395
may show one piece of data or function, or a plurality of data and
functions.
[0051] Apparatus 300 includes intake vents 370. In certain
approaches, intake vents 370 include a filtering system, such as
filter 170 of device 100. The filtering system may comprise a
lattice type structure capable of accepting a filter or filtering
material. The filtering material may comprise any type of material
commonly used to filter particles from the air.
[0052] PAP apparatus 300 may be any appropriate size. In certain
approaches, apparatus has 300 has a length of between approximately
1 inches and approximately 10 inches, a width between approximately
1 inch and approximately 10 inches and a height between
approximately 1 inch and approximately 10 inches. For example, in
certain approaches, PAP apparatus 300 has dimensions of
approximately 5.63 inches in height, 3.11 inches in width, and 1.75
in height.
[0053] However, the length, width, and height may vary from
embodiment to embodiment depending on the size of the blower or
motor, the desired single chamber volume, or any other factor that
may affect the external dimensions.
[0054] FIG. 3B illustrates a perspective view of PAP apparatus 300,
including an adapter 360. In certain approaches, adapter 360 is
solitary in construction with the housing, such as lower housing
component 380 and/or upper housing component 381. In certain
embodiments, adapter 360 may be a separate piece, with a proximal
portion secured within the interior portion of apparatus 300 and a
distal portion extending outward from apparatus 300.
[0055] FIG. 3C depicts apparatus 300 with adapters and an interface
components for providing positive air pressure to a patient. A
male/female (m/f) adapter 361 couples to adapter 360 of apparatus
300. For example, first end 362 of adapter 361 may be a male end
that couples within adapter 360. Male/female adapter 361 also
couples to patient interface system 365. For example, second end
363 may be a male end that couples to proximal end 364 of patient
interface system 365. In certain approaches, patient interface
system 365 is shaped and configured to couple directly to apparatus
300, thus eliminating the need for an intermediate adapter, such as
male/female adapter 361. In certain embodiments, the coupling ends,
such as adapter 360, first end 362, second end 363, and proximal
end 364 may have shapes such as ovals, to provide directional
fit.
[0056] In certain embodiments, PAP apparatus 300 may include an
outer casing. In some embodiments, the outer casing may further
comprise an energy source. For example, the outer casing may
include a battery or a power connector. In some embodiments, a
battery pack or power source is directly attached or connected to
the CPAP device.
[0057] FIG. 4 depicts the interior of a portable PAP apparatus 400.
PAP apparatus 400 includes an attenuation intake chamber 402 with
sound attenuators 410 positioned within intake chamber 402. In
certain approaches, intake chamber 402 includes foam 406 to reduce
the acoustic output of apparatus 400. Although foam is described,
any dissipative element could be used. Dissipative elements may
include anechoic materials such as foam, rubber, clay, silicon, or
any other suitable soft and/or porous materials. Additionally or
alternatively, apparatus 400 includes intake vents 412, through
which air may flow.
[0058] PAP apparatus 400 has an acoustic chamber 414 with an inlet
port 422 coupled to intake chamber 402. An intake tube 404 extends
from intake chamber 402, through inlet port 422, and into acoustic
chamber 414. Intake tube 404 includes opening 408 to enable air
flow from intake chamber 402 into acoustic chamber 414. When in
operation, blower 416 is powered on and pulls air through vents 412
into opening 408, through tube 404, and into blower 416. Blower 416
then pushes air through outlet tube 418 and through opening 420
into a patient interface, such as patient interface 165.
[0059] The size and location of intake tube 404 and opening 408 may
be determined based on the location and size of attenuators 410.
Intake tube 404 may extend past attenuators 410. For example,
opening 408 may have a diameter of approximately 0.5 inches and
intake tube 404 may extend into attenuating intake chamber 402
approximately 0.875 inches beyond attenuators 410. In certain
embodiments, the diameter of opening 408 along the length of intake
tube 404 varies in diameter. For example, the diameter may vary
from approximately 0.25 inches to 0.75 inches. In certain
embodiments, intake tube 404 extends into attenuating intake
chamber 402 so that opening 408 is substantially even with
attenuators 410. In certain approaches, intake tube 414 extends
past attenuators 410 by more than approximately 1 inch.
[0060] FIG. 5 depicts the interior of a portable PAP apparatus 500.
PAP apparatus 500 includes an attenuation intake chamber 502 with
sound attenuators 510 positioned within intake chamber 502. In
certain approaches, intake chamber 502 includes foam 506 to reduce
the acoustic output of apparatus 500. Although foam is described,
any dissipative element could be used. Dissipative elements may
include anechoic materials such as foam, rubber, clay, silicon, or
any other suitable soft and/or porous materials. Additionally or
alternatively, apparatus 500 includes intake vents 512, through
which air may flow.
[0061] PAP apparatus 500 has an acoustic chamber 514 coupled to
intake chamber 502 via inlet port 507. In certain approaches,
apparatus 500 includes a first intake tube 509 extending into
intake chamber 502. Apparatus 500 includes a barrier 504, which
forms a flow space 505, which is in fluid communication with first
intake tube 509. As depicted, flow space 505 can have turns or
bends. Barrier 504 may be configured such that flow space 505
defines any number of turns, wherein each turn has any angular
dimension (e.g., sixty degrees, ninety-degrees, one-hundred-eighty
degrees, etc.) and any combination of vertical and horizontal
turns. In certain approaches, barrier 504 is firm and inflexible.
When in operation, blower 516 is powered on and pulls air through
vents 512, into opening 508 of intake tube 509, through tube 509,
through inlet port 507, through flow space 505, into acoustic
chamber 514, and into blower 516. Blower 516 then pushes air
through outlet tube 518 and through opening 520 into a patient
interface, such as patient interface 165.
[0062] The intake chamber may be on any appropriate side (e.g.,
back, side, top, bottom, etc.) of the apparatus. For example, FIG.
6 depicts the interior of a portable PAP apparatus 600 with an
intake chamber 602 positioned on a side of apparatus 600. Intake
chamber 602 includes sound attenuators 610 positioned within intake
chamber 602. In certain approaches, intake chamber 602 includes
foam 606 to reduce acoustic output of apparatus 600. Although foam
is described, any dissipative element could be used. Dissipative
elements may include anechoic materials such as foam, rubber, clay,
silicon, or any other suitable soft and/or porous materials.
Additionally or alternatively, apparatus 600 includes intake vents
612 and 613, through which air may flow. In the depicted example,
intake vents 613 are positioned at the top and/or bottom of
apparatus 600.
[0063] PAP apparatus 600 has an acoustic chamber 614 with an inlet
port 622 coupled to intake chamber 602. An intake tube 604 extends
from intake chamber 602, through inlet port 622, and into acoustic
chamber 614. Intake tube 604 includes opening 608 to enable air
flow from intake chamber 602 into acoustic chamber 614. Although
depicted as straight, intake tube 604 may include any number of
turns. When in operation, blower 616 is powered on and pulls air
through vents 612 and vents 613, into opening 608, through tube
604, and into blower 616. Blower 616 then pushes air through outlet
tube 618 and through opening 620 into a patient interface, such as
patient interface 165.
[0064] FIGS. 7A-7D depict a PAP apparatus having an internal
pressure sensor. CPAP device 700 is similar to previously described
CAP devices and apparatuses, such as device 100. Device 700 has a
lower housing component 780, which together with an upper housing
component 784, defines sealed chamber 730. Sealed chamber 730 has
an inlet port 710 and an outlet port 739. A motor or blower 740 is
placed within chamber 730. In some embodiments, foam or another
anechoic material (not depicted) may be placed within chamber 730
to further attenuate noise produced during the operation of device
700.
[0065] Device 700 additionally includes connector portion 785 to
couple lower housing 780 and upper housing 784 together, thereby
creating a seal. In the depicted example, connector portions 785
are positioned around the perimeter of the housing. A fastener,
such as a screw, may be used to couple lower housing 780 and upper
housing 784. Additionally or alternatively, the edge 782 of the
housing may provide a coupling and/or sealing mechanism. For
example, edge 782 may has a tongue, which fits into a groove on the
edge of upper housing 784. Edge 782 may also include a seal, such
as santoprene or silicone.
[0066] Inlet port 710 includes an intake tube 715 having a first
end 712 extending through lower housing 780 and a second end 720
that extends into chamber 730. Intake tube 715 may have either a
constant or varying internal diameter. The cross-sectional shape
may be circular, square, oval, rectangular, triangular or any other
shape. For example, the internal diameter may range from
approximately 0.25 inches to approximately 0.75 inches and may have
a length ranging from approximately 0.25 inches to approximately 3
inches, although any appropriate diameter and length may be used.
The length and diameter of intake tube 715 affect the overall noise
attenuation of the CPAP device, as previously discussed.
Accordingly, in some approaches, the dimensions of intake tube 715
are proportionally related to the volume of chamber 730.
[0067] Intake tube 715 may be formed using rigid materials,
flexible materials, or any combination thereof. For example, intake
tube 715 may be formed using a hard plastic. In certain
embodiments, intake tube 715 is composed of flexible
polyvinylchloride (PVC) tubing, silicone tubing, or any other type
of tubing commonly used in the art.
[0068] In certain approaches, outlet port 739 includes outlet tube
745, which extends from blower outlet 737 through the lower housing
780. An adapter 760 may be used to connect the blower outlet tube
745 to a patient interface, such as patient interface 165. Outlet
tube 745 may also vary in length and diameter.
[0069] Apparatus 700 includes a pressure port 762. Pressure port
762 has a first end 764 on the exterior of lower housing 780 and
upper housing 784. First end 764 is coupled to adapter 760.
Pressure port 762 runs through housing 780 into chamber 730, where
the second end 768 couples to pressure sensor 745. Pressure port
762 provides fluid communication from the output of device 700 at
adapter 760 to pressure sensor 745. In certain approaches, sensor
745 is on circuitry board 744. Circuitry board 744 includes control
circuitry and control components for the operation of device 700.
Circuitry board 744 may be positioned over outlet tube 745. In
certain approaches, circuitry board 744 includes a power source,
such as a power adapter or battery. In certain approaches, the
control circuitry on board 744 of device 700 is configured to
display the pressure measured by pressure sensor 745 through
pressure port 762 at display 788 of control panel 786 on upper
housing 784. Display 788 may be similar to previously described
display 395. In certain embodiments, the pressure output of device
700 may be adjusted manually by the user with user interface
buttons 785. User interface buttons 785 may be similar to
previously described buttons 390. In certain approaches, the
control circuitry on board 744 is configured to automatically
adjust the output of device 700 based on the pressure measurements
from pressure sensor 745. The output of device 700 may be adjusted
by modulating the power of blower 740.
[0070] During operation, PAP device 700 creates positive air
pressure through outlet port 739. For example, when a patient
interface is attached to adapter 760, PAP device 700 creates
positive air pressure, which can be provided to the patient when
the patient places the adapter at his or her airways (e.g., nose or
mouth). When blower 740 is powered on, blower 740 pulls air through
inlet port 710 into chamber 730 and into blower 740. Blower 740
then pushes air through outlet 737, through outlet tube 745, and
through outlet port 739 to thereby provide positive air pressure
through outlet port 739.
[0071] As depicted in FIG. 7D, device 700 may include an intake
cover 790. Intake cover 790 serves to prevent the occlusion of
inlet port 710 during use of device 700. Intake cover 790 includes
a vented portion 792 to allow the pass through of air during
operation of device 700. In certain embodiments, intake cover 790
may include a filter to clean the air of particulate matter. In
certain embodiments, intake cover 790 is removable so that it may
be cleaned, replaced, or adapted for a particular need.
[0072] In certain embodiments, air may be passed through intake
cover 790 before entering inlet port 710. In certain approaches,
the pressurized air is delivered to a patient through a patient
interface at a pressure ranging from approximately 2 centimeters
(cm) of water to approximately 40 cm of water above atmospheric
pressure at the point of use, although any appropriate pressure may
be used.
[0073] FIG. 8A depicts one embodiment of an acoustically invisible
cover 800. Cover 800 may be similar to cover 790 and is positioned
on the housing over the inlet port (such as inlet port 110 or inlet
port 710) to prevent occlusion of the inlet port during use. Cover
800 includes a first portion 804, which is shaped similar to the
housing of a PAP device (such as device 100 or device 700) so that
it can couple directly to the housing. Cover 800 includes a flow
portion 802, which is sufficiently porous so that air can flow
through it. In certain embodiments, flow portion 802 is constructed
of a mesh material, such as a metal or plastic. For purposes of
this application `acoustically invisible` is defined as not adding
more than 3 dBA of sound to the overall PAP device. Ideally less
than 1 dBA, or less than 0.5 dBA or something even less negligible
is achieved.
[0074] FIG. 8B depicts an embodiment of a cover 810. Cover 810 may
be similar to cover 790 or cover 800 and is positioned on the
housing over the inlet port (such as inlet port 110 or inlet port
710) to prevent occlusion of the inlet port during use. Cover 810
includes a first portion 814, which is shaped similar to the
housing of a PAP device (such as device 100 or device 700) so that
it can couple directly to the housing. Cover 810 includes flow
portion 812, which is sufficiently porous so that air can flow
through it. For example, flow portion 812 may be constructed of
paper or mesh. In certain approaches, flow portion 812 includes
vents such as vents 816. However, if flow portion 812 were not
constructed of mesh, paper, or plastic that was sufficiently porous
and was solid instead, the vents 816 may actually cause the overall
dBA of the device to increase such that it would not be
acoustically invisible.
[0075] In the absence of any additional outside attenuators, the
CPAP device disclosed herein, having one interior attenuator,
produces noise levels of about 30 dBA or less. In some instances as
low as 26 dBA or less.
[0076] FIG. 9 depicts the interior of a dual chamber PAP apparatus
900. CPAP device 900 has a lower housing component 980, which
together with an upper housing component (not shown) defines a
first sealed chamber 930 and a second sealed chamber 934 separated
by wall 932. First sealed chamber 930 has an inlet port 910 with
intake tube 915, which extends through housing 980, through second
chamber 934, and through wall 932 into first chamber 930. A first
portion 912 of tube 915 is outside housing 980 and a second portion
920 is inside sealed chamber 930. In some embodiments, the first
chamber may further include a noise attenuator 931 positioned
within the airflow path from portion 920 of intake tube 915. Again
for clarity, tubes described do not necessarily have to be circular
in cross-section or round. They can include square, rectangular,
and other shapes.
[0077] Device 900 includes an interchamber port 917, which allows
air to flow from the first chamber 930 to the second chamber 934.
In certain approaches, interchamber port 917 includes a tube 916,
which extends from first chamber 930, through through wall 932, and
into second chamber 934.
[0078] The first and second chambers are separated by a chamber
wall 932. In some embodiments, chamber wall 932 may be formed on
lower housing 932 and/or the upper housing (not depicted). In
certain approaches, chamber wall 932 is solitary in construction
with the housing. Additionally or alternatively, chamber wall 932
may be secured to the respective housing components with an
adhesive or glue. Additionally or alternatively, chamber wall 932
may be formed from an anechoic material such as foam, rubber, clay,
silicon, or any other suitable soft and/or porous materials. In
certain embodiments, chamber wall 932 may be formed using a rigid
material, such as a hard plastic.
[0079] A motor or blower 940 is located within second chamber 934.
In certain embodiments, blower 940 is secured to chamber 934 using
one or more mount connects 950. In some embodiments, the mount
connects may further comprise pivoting cone connectors, circular
donut shaped mount connects, a silicone cradle, or any combination
thereof. For example, the mount connects may comprise pivoting cone
connectors that connect the top of blower 940 within chamber 934
and circular donut shaped mount connects that connect the bottom of
blower 940 within chamber 930. In addition to connecting blower 940
to the housing, mount connects 940 may reduce or eliminate transfer
of vibrations from the blower to other components of device 900. In
certain embodiments, blower 940 is a brushless air-bearing
motor.
[0080] In some embodiments, foam or another anechoic material may
be placed within chamber 930 and chamber 934 to further attenuate
noise produced during the operation of device 900. The anechoic or
noise attenuating material may be secured at specific locations
within each chamber. In additional embodiments, the lower and/or
upper housing components may be lined with an anechoic or noise
attenuating material. In such embodiments, the anechoic or noise
attenuating material may include foam, rubber, clay, silicon, or
any other suitable soft and/or porous materials.
[0081] In at least one embodiment, first chamber 930 further
comprises an attenuator 931 which may be placed within the chamber
directly across from the proximal end 920 of intake tube 915.
Attenuator 931 is positioned within the airflow path to thereby
attenuate noise created by the flow of air through chamber 930. In
certain approaches, attenuator 931 is angled toward the intake tube
having an acute angle relative to the housing component. In certain
approaches, device 900 includes a plurality of attenuators. In
certain approaches, device 900 includes at least one attenuator in
second chamber 934. When a plurality of attenuators are included,
each attenuator, such as attenuator 931, within the chamber 930 or
chamber 934 may be oriented in varying angles relative to the end
of intake tube 915, interchamber tube 916, and/or the housing
components. While the attenuators may vary in size, length,
quantity, shape, angle, and/or location, they may divert the
airflow pathway and reduce the amount of noise exiting the CPAP
device. Attenuators may further comprise a dissipative element,
noise attenuating coating, and/or a noise attenuating material
attached thereto. For example, attenuator 931 may be composed of or
coated with an anechoic or noise attenuating material. The anechoic
or noise attenuating material may include foam, rubber, clay,
silicon, or any other suitable soft and/or porous materials.
[0082] Device 900 additionally includes one or more connector
portions 985 to couple lower housing 980 and upper housing
together, thereby creating a seal. In the depicted example, the
connector portions 985 are positioned around the perimeter of the
housing. A fastener, such as a screw, may be used to couple the
housing. Additionally or alternatively, edge 982 of the housing may
provide a coupling and/or sealing mechanism. For example, edge 982
has a tongue, which may couple to a groove in an upper housing
portion. Edge 982 may also include a seal, such as santoprene or
silicone.
[0083] Intake tube 915 and interchamber tube 916 may have either a
constant or varying internal diameter. For example, an interior
diameter may range from approximately 0.25 inches to approximately
0.75 inches and may have a length ranging from approximately 0.25
inches to approximately 3 inches, although any appropriate diameter
and length may be used. The length and diameter of intake tube 915
affect the overall noise attenuation of the CPAP device, as further
discussed in relation to FIG. 2 and equation 1 and equation 2.
Accordingly, in some approaches, the dimensions of intake tube 915
and interchamber tube 916 are proportionally related to the volume
of chamber 930.
[0084] Intake tube 915 and interchamber tube 916 may be formed
using rigid materials, flexible materials, or any combination
thereof. For example, intake tube 915 and interchamber tube 916 may
be formed using a hard plastic. In certain embodiments, intake tube
915 and interchamber tube 916 are composed of flexible
polyvinylchloride (PVC) tubing, silicone tubing, or any other type
of tubing commonly used in the art. Intake tube 915 and
interchamber tube 916 may be composed of different materials.
[0085] In certain approaches, outlet port 939 includes outlet tube
945, which extends from blower outlet 937 into second chamber 934,
through wall 932, through first chamber 930, and through housing
980. An adapter 960 may be used to connect the blower outlet tube
945 to patient interface 965. In embodiments having an adapter, the
adapter may be solitary in construction and configured so that a
proximal portion of the adapter may be secured and sealed to the
housing of device 900, while a distal portion of the adapter
extends outward from device 900. The lower housing component 980
and the upper housing component may each include a detent (not
pictured) capable of accepting a portion of the adapter, whereby
the two housing components together form a seal around the
circumference of a portion of the adapter.
[0086] Outlet tube 945 may also vary in length and diameter. The
length of the blower outlet tube 945 is long enough to connect to
outlet 937 of blower 940 through outlet port 939. Outlet tube 945
provides a sealed airway between blower 940 and adapter 960 and/or
patient interface system 965. Additionally, depending on the
dimensions of blower 940, the inner diameter of the outlet tube 945
may vary so long as the diameter is large enough to fit over and
seal with outlet 937 and adapter 960 and/or patient interface
system 965. Outlet tube 945 may be formed using rigid materials,
flexible materials, or any combination thereof. For example, outlet
tube 945 may be formed using a hard plastic. In certain
embodiments, outlet tube 945 is composed of flexible
polyvinylchloride (PVC) tubing, silicone tubing, or any other type
of tubing commonly used in the art.
[0087] Apparatus 900 includes a pressure port 962. Pressure port
962 is coupled to adapter 960. Pressure port 962 runs through
housing 980 into chamber 930, where pressure port 962 couples to a
pressure sensor, such as a pressure sensor on circuitry board 944.
Pressure port 962 provides fluid communication from the output of
device 900 at adapter 960 to a pressure sensor coupled to control
circuitry. Circuitry board 944 includes control circuitry and
control components for the operation of device 900. Circuitry board
944 may be positioned over or under outlet tube 945. In certain
approaches, circuitry board 944 includes a power sources, such as a
power adapter or battery. In certain approaches, the control
circuitry on board 944 of device 900 is configured to display the
pressure measured through pressure port 962 at a display, such as
display 788 depicted in FIG. 7. In certain embodiments, the
pressure output of device 900 may be adjusted manually by the user
with user interface buttons. In certain approaches, the control
circuitry on board 944 is configured to automatically adjust the
output of device 900 based on the pressure measurements. The output
of device 900 may be adjusted by modulating the power of blower
940.
[0088] Although not depicted, device 900 may include a cover, such
as cover 790, cover 800, or cover 810, which covers and prevents
the occlusion of inlet port 910
[0089] During operation, PAP device 900 creates positive air
pressure through outlet port 939. For example, when patient
interface 965 is attached, PAP device 900 creates positive air
pressure, which can be provided to the patient when the patient
places the adapter at his or her airways (e.g., nose or mouth).
Blower 940 includes intake 935. When blower 940 is powered on,
blower 940 intakes air through intake 935 and pushes out that air
through outlet 937. The reduced pressure at intake 935 causes air
to flow through inlet port 910 into chamber 930, where it then
flows through interchamber port 917 into second chamber 934, and
into intake 935 of blower 940. Blower 940 then pushes the air
through outlet 937, through outlet tube 945, and through outlet
port 939 to thereby provide positive air pressure through outlet
port 939. In certain embodiments, air may be initially passed
through a pre-intake chamber, such as pre-intake chamber 172 as
described in relation with device 100, before entering inlet port
910. In certain approaches, the pressurized air is delivered to a
patient through patient interface 965 at a pressure ranging from
approximately 2 centimeters (cm) of water to approximately 40 cm of
water above atmospheric pressure at the point of use, although any
appropriate pressure may be used.
[0090] Both the first chamber 930 and second chambers 934 may be
designed to reduce the amount of noise released from CPAP device
900 during operation. In such embodiments, the chambers may be
designed to operate as a high-pass, low-pass, band filter, or a
combination thereof. For example, in one embodiment, first chamber
930 may be designed as a low-pass filter, while second chamber 934
is designed as a high-pass filter. In additional embodiments, first
chamber 930 and second chamber 934 may both operate as low-pass
filters.
[0091] In certain approaches, first chamber 930 and second chamber
934 have a combined volume ranging from approximately 200
milliliters (mL) to approximately 485 mL. For example, the combined
volume of first chamber 930 and second chamber 934 may be
approximately 481 mL. The combined volume of first chamber 930 and
second chamber 934 may be approximately 395 mL. The combined volume
of first chamber 930 and second chamber 934 may be less than 360
mL.
[0092] Additionally or alternatively, first chamber 930 and second
chamber 934 may have equivalent volumes. In certain approaches, one
of the chambers may have a larger volume than the other chamber. In
certain embodiments the second acoustic chamber, which houses the
blower, is larger than the first acoustic chamber. For example, in
an embodiment where the combined volume is approximately 270 mL,
first chamber 930 may have a volume ranging from approximately 70
mL to approximately 170 mL, and second chamber 934 may have a
volume ranging from approximately 100 mL to approximately 200 mL.
As an additional example, in an embodiment where the combined
volume is approximately 480 mL, first chamber 930 may have a volume
ranging from approximately 100 mL to approximately 240 mL, while
second chamber 934 may have a volume ranging from approximately 240
mL to approximately 380 mL.
[0093] In some embodiments it is advantageous to have the first
acoustic chamber (such as 930) proportionally sized to the inlet
port 910, yet be smaller than the second acoustic chamber 934, such
that a sufficiently sized blower and its motor may be completely
disposed within the second acoustic chamber.
[0094] As is shown in both Equation 1 and FIG. 2, inlet port 910
and interchamber port 917 may each have a cross-sectional area that
is proportionally related to the volume of chambers 930 and 934
respectively and balanced with the necessary work of the motor
required to generate a desired amount flow. As previously
mentioned, this increase in work may increase the noise generated
by the blower and thus needs to be balanced with the
cross-sectional areas of the ports 910 and 917. In other
embodiments however, inlet ports may be designed without using
Equations 1 & 2.
[0095] The above description is merely illustrative. Having thus
described several aspects of at least one embodiment of this
invention including the preferred embodiments, it is to be
appreciated that various alterations, modifications, and
improvements will readily occur to those skilled in the art. Such
alterations, modifications, and improvements are intended to be
part of this disclosure, and are intended to be within the spirit
and scope of the invention. Accordingly, the foregoing description
and drawing are by way of example only.
* * * * *