U.S. patent application number 14/968091 was filed with the patent office on 2016-04-21 for pump and housing configuration for inflating and deflating an air mattress.
The applicant listed for this patent is RAPID AIR LLC. Invention is credited to David Delory Driscoll, JR., Susan Marie Hrobar, John Joseph Riley.
Application Number | 20160106224 14/968091 |
Document ID | / |
Family ID | 47296413 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160106224 |
Kind Code |
A1 |
Driscoll, JR.; David Delory ;
et al. |
April 21, 2016 |
PUMP AND HOUSING CONFIGURATION FOR INFLATING AND DEFLATING AN AIR
MATTRESS
Abstract
Efficient systems and methods for inflating, deflating, or
simultaneously inflating and deflating air mattress chambers using
various pump and pump housing configurations are provided. Examples
of the various pump and pump housing configurations include:
boundary-layer pumps having single disk array or multiple disk
array layouts, different disk geometries, different pressure
recovery chamber geometries, adjustable components for switching
between filling and powered dumping operations, and reversible and
non-reversible motors; and pump housings having one or more dump
channels for manifold-driven powered dumping, multiple sides or
stages for pressure and/or flow compounding, various manifold
chamber configurations for robust connectivity with air mattresses
having multiple chambers, and various valve configurations for
flexible control over filling, powered dumping, and simultaneous
filling and powered dumping operations. Pump products having pumps
and pump housings designed according to the principles described
herein are able to satisfy a wide range of different performance
and cost requirements.
Inventors: |
Driscoll, JR.; David Delory;
(Milwaukee, WI) ; Riley; John Joseph; (Brookfield,
WI) ; Hrobar; Susan Marie; (Brookfield, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RAPID AIR LLC |
Pewaukee |
WI |
US |
|
|
Family ID: |
47296413 |
Appl. No.: |
14/968091 |
Filed: |
December 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13490205 |
Jun 6, 2012 |
9211019 |
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14968091 |
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13426359 |
Mar 21, 2012 |
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13490205 |
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61493836 |
Jun 6, 2011 |
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61454888 |
Mar 21, 2011 |
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Current U.S.
Class: |
5/706 ;
415/204 |
Current CPC
Class: |
F04D 29/281 20130101;
A47C 27/083 20130101; F04D 17/161 20130101; F04D 25/06 20130101;
F04D 29/4206 20130101; A47C 27/10 20130101; F04D 17/08 20130101;
F04D 25/084 20130101; F04D 17/164 20130101; A47C 27/082
20130101 |
International
Class: |
A47C 27/08 20060101
A47C027/08; F04D 29/42 20060101 F04D029/42; F04D 25/06 20060101
F04D025/06; F04D 29/28 20060101 F04D029/28; A47C 27/10 20060101
A47C027/10; F04D 17/08 20060101 F04D017/08 |
Claims
1. An airbed system, comprising: an air mattress having at least
one air mattress chamber; a boundary-layer pump connected to the at
least one air mattress, configured to fill the at least one air
mattress with gas, the boundary-layer pump comprising: a pressure
recovery chamber housing including a pressure recovery chamber, a
pump inlet, and a pump outlet; a plurality of disks within the
pressure recovery chamber; and a motor attached to the plurality of
disks, configured to rotate the plurality of disks; wherein the
plurality of disks are configured such that rotation of the
plurality of disks, utilizing viscous boundary layer adhesion
forces, imparts a velocity profile having a centrifugal component
and a radial component to gas entering the boundary-layer pump
through the pump inlet so as to impel the gas radially outwards
from centers of the plurality of disks towards edges of the
plurality of disks based on the imparted velocity profile; and a
control unit, configured to receive user input corresponding to
increasing or decreasing the pressure in the at least one air
mattress chamber and to control the boundary-layer pump based on
the received user input; wherein the pressure recovery chamber
comprises a pressure recovery involute spanning approximately 360
degrees having a curvature defined by the edges of the plurality of
disks and interior walls of the pressure recovery chamber housing,
wherein the width of the pressure recovery involute, defined by the
distance between the edges of the plurality of disks and the
interior walls of the pressure recovery chamber housing, decreases
along the pressure recovery involute from the pump outlet to a
region of the pressure recovery involute farthest from the pump
outlet along a flow path of the pressure recovery involute.
2. The airbed system of claim 1, wherein the boundary-layer pump
further comprises: a base disk, positioned farther from the pump
inlet than the plurality of disks.
3. The airbed system of claim 2, wherein the base disk is closest
to the motor out of the plurality of disks.
4. The airbed system of claim 2, wherein the base disk is farthest
from the motor out of the plurality of disks.
5. The airbed system of claim 1, wherein dimensions of the pressure
recovery involute are based on disk geometry, number of disks, and
an operable range of revolutions per minute.
6. The airbed system of claim 1, wherein disks of the plurality of
disks include disk inlet areas.
7. The airbed system of claim 6, wherein the disk inlet areas of
the plurality of disks forms a tapered flow channel.
8. The airbed system of claim 1, wherein the motor is reversible;
and wherein operation of the motor in one direction corresponds to
a pumping operation with respect to the at least one air mattress
chamber and operation of the motor in the other direction
corresponds to a powered dumping operation with respect to the at
least one air mattress chamber.
9. The airbed system of claim 8, wherein the boundary-layer pump
further comprises: an exhaust outlet; a plug, configured to isolate
the pressure recovery chamber from the exhaust outlet in a first
position during filling operation and, in a second position, to
connect the pressure recovery chamber to the exhaust outlet during
the powered dumping operation; and a valve for blocking the pump
inlet during the powered dumping operation; wherein the plurality
of disks are further configured such that rotation of the plurality
of disks in a reverse direction during powered dumping operation
impels gas entering the boundary-layer pump through the pump outlet
towards the exhaust outlet.
10. The airbed system of claim 9, wherein the pressure recovery
chamber includes a first pressure recovery involute geometry during
the filling operation defined by the edges of the plurality of
disks, interior walls of the pressure recovery chamber housing, and
the plug in the first position, and wherein the pressure recovery
chamber includes a second pressure recovery involute geometry
during the powered dumping operation defined by the edges of the
plurality of disks, interior walls of the pressure recovery chamber
housing, and the plug in the second position.
11. The airbed system of claim 8, wherein the boundary-layer pump
further comprises: an exhaust outlet; and an adjustable sheath,
configured to isolate the pressure recovery chamber from the
exhaust outlet during filling operation in a first position, and
further configured to connect the pressure recovery chamber to the
exhaust outlet during the powered dumping operation and block the
pump inlet during powered dumping operation in a second position;
wherein the plurality of disks are further configured such that
rotation of the plurality of disks in a reverse direction during
the powered dumping operation impels gas entering the
boundary-layer pump through the pump outlet towards the exhaust
outlet.
12. The airbed system of claim 11, wherein the pressure recovery
chamber includes a first pressure recovery involute geometry during
the filling operation defined by the edges of the plurality of
disks, interior walls of the pressure recovery chamber housing, and
the adjustable sheath in the first position; and a second pressure
recovery involute geometry during the powered dumping defined by
the edges of the plurality of disks, interior walls of the pressure
recovery chamber housing, and the adjustable sheath in the second
position.
13. The airbed system of claim 1, further comprising: a manifold
chamber, wherein the boundary-layer pump is connected to the air
mattress via the manifold chamber.
14. The airbed system of claim 13, further comprising: a dump
channel, configured to provide a connection between the manifold
chamber and the pump inlet during a powered dumping operation.
15. The airbed system of claim 13, further comprising: means for
switching the system between modes of operation, the modes of
operation including an inflate operation where operation of the
boundary-layer pump impels gas from the boundary-layer pump into a
chamber of the air mattress and a powered dumping operation where
operation of the boundary-layer pump impels gas from the chamber of
the air mattress out of the boundary-layer pump.
16. The airbed system of claim 13, wherein the air mattress
comprises a plurality of chambers and the manifold chamber is
connected to the plurality of chambers of the air mattress; and
wherein the manifold chamber is configured to provide independent
pumping or powered dumping operations with respect to each of the
plurality of air chambers of the air mattress.
17. The airbed system of claim 13, wherein the manifold chamber is
switchable between different configurations, including a
configuration where one air chamber of the air mattress is inflated
while another air chamber of the air mattress is deflated.
18. The airbed system of claim 13, wherein the manifold chamber is
switchable between different configurations, including
configurations where multiple air chambers of the air mattress are
simultaneously inflated or deflated.
19. A boundary-layer pump for an airbed system, the boundary-layer
pump comprising: a pressure recovery chamber including: a pressure
recovery involute; a pump inlet for receiving gas into the pressure
recovery chamber; and a pump outlet connected to the air mattress
chamber; a plurality of disks within the pressure recovery chamber;
and a motor for rotating the plurality of disks; wherein the
plurality of disks are configured such that rotation of the
plurality of disks, utilizing viscous boundary layer adhesion
forces, imparts a velocity profile having a centrifugal component
and a radial component to gas entering the boundary-layer pump
through the pump inlet so as to impel the gas radially outwards
from centers of the plurality of disks towards edges of the
plurality of disks based on the imparted velocity profile; and
wherein the pressure recovery involute has a curvature defined by
the edges of the plurality of disks and interior walls of the
pressure recovery chamber housing spanning approximately 360
degrees, wherein the width of the pressure recovery involute,
defined by the distance between the edges of the plurality of disks
and the interior walls of the pressure recovery chamber housing,
decreases along the pressure recovery involute from the pump outlet
to a region of the pressure recovery involute farthest from the
pump outlet.
20. The boundary-layer pump of claim 19, wherein the motor is
reversible; and wherein operation of the motor in one direction
corresponds to a pumping operation with respect to the at least one
air mattress chamber and operation of the motor in the other
direction corresponds to a powered dumping operation with respect
to the at least one air mattress chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation of copending U.S.
patent application Ser. No. 13/490,205, filed on Jun. 6, 2012,
which claims the benefit of U.S. Provisional Patent Application No.
61/493,836, filed on Jun. 6, 2011. U.S. patent application Ser. No.
13/490,205 is a continuation-in-part of U.S. patent application
Ser. No. 13/426,359, filed on Mar. 21, 2012, which claims the
benefit of U.S. Provisional Patent Application No. 61/454,888,
filed Mar. 21, 2011. All of the foregoing U.S. patent applications
and U.S. Provisional patent applications are incorporated by
reference herein in their entireties.
BACKGROUND
[0002] Commercial airbeds have been growing steadily in popularity.
Many types of airbeds have been developed for a variety of
applications over the years, ranging from simple and inexpensive
airbeds that are convenient for temporary use (such as for house
guests and on camping trips), home-use airbeds that replace
conventional mattresses in the home, to highly sophisticated
medical airbeds with special applications (such as preventing
bedsores for immobile patients). With respect to home-use and
medical airbeds, more and more consumers are turning to these types
of airbeds for the flexibility in firmness that they offer,
allowing consumers to adjust their mattresses to best suit their
preferences.
[0003] Conventional home-use and medical airbeds generally include
at least a few main components: a mattress with at least one
chamber that can be filled with air, a unit for pumping air into
the chamber, and appropriate connections between the mattress and
the pumping apparatus. The pumping unit may further include a pump
connected to a manifold, with a control mechanism and valves for
controlling the pumping of air into the mattress and releasing the
air out of the mattress. Conventional pumps used in airbeds are
"squirrel-cage" blowers and diaphragm pumps.
[0004] The squirrel-cage blowers used in airbeds are relatively
inexpensive and simple pumps that rely on a fan to push air into
the mattress. While the squirrel-cage blower is able to achieve a
relatively high flow rate (e.g. around 75 L/min) and inflate a
mattress relatively quickly, it is unable to produce pressures that
are high enough to meet the desirable range of pressure for all
home-use and medical airbeds (up to about 1 psi), as squirrel-cage
blowers are generally limited to about 0.1-0.5 psi. Squirrel-cage
blowers tend to be inefficient and therefore will generate higher
levels of heat when they are running compared to diaphragm
pumps.
[0005] The diaphragm pumps used in airbeds, which rely on
quasi-positive displacement technology, are generally able to
achieve pressures of up to about 5 psi, well beyond the
requirements of the airbed industry. However, diaphragm pumps are
not capable of as much air flow as squirrel-cage blowers (limited
to about 25-50 L/min), and thus take a longer amount of time to
fill an air mattress. Diaphragm pumps also generate a moderate
amount of noise, but less than squirrel-cage blowers. Diaphragm
pumps, for the same relative performance as a squirrel-cage blower,
will be two to three times more expensive.
[0006] More sophisticated airbeds used in medical applications
(e.g. home-care airbeds) have been able to deal with these problems
to some degree by integrating both a diaphragm pump and a squirrel
cage blower in their airbeds, as well as adding a noise-cancelling
housing to encase the pumps. These medical airbeds can start off by
filling the airbed quickly at a low pressure with a squirrel cage
blower, and switch over to a diaphragm pump to finish the filling
and achieve the desired pressure. Additionally, medical airbeds may
take into account whether the patient on the bed is asleep or awake
in determining which pump to use (e.g. using the noisier squirrel
cage pump for rolling over a patient that is awake, or using the
relatively quieter diaphragm pump for supplying a constant flow for
a wound-care type mattress running while the patient is asleep).
However, these solutions result in a steep increase in cost, as
well as increasing the size and complexity of the entire pumping
unit.
[0007] It will be appreciated that the foregoing is a discussion of
problems discovered and/or appreciated by the inventors, and is not
an attempt to review or catalog the prior art.
SUMMARY
[0008] The present invention provides efficient and cost-effective
systems and methods for inflating, deflating, or simultaneously
inflating and deflating air mattress chambers using various pump
and pump housing configurations. Examples of the various pump and
pump housing configurations include: boundary-layer pumps having
single disk array or multiple disk array layouts, different disk
geometries, different pressure recovery chamber geometries,
adjustable components for switching between filling and powered
dumping operations, and reversible and non-reversible motors; and
pump housings having one or more dump channels for manifold-driven
powered dumping, multiple sides or stages for pressure and/or flow
compounding, various manifold chamber configurations for robust
connectivity with air mattresses having multiple chambers, and
various valve configurations for flexible control over filling,
powered dumping, and simultaneous filling and powered dumping
operations. Pump products having pumps and pump housings designed
according to the principles described herein are able to satisfy a
wide range of different performance and cost requirements.
[0009] In an embodiment, a system for utilizing a pump to inflate
and deflate an air mattress is provided. The system includes: an
air mattress having at least one chamber; a pump adapted to receive
a gas through a pump inlet and impel the gas through a pump outlet;
and a manifold chamber including at least one outlet connecting the
manifold chamber to the at least one chamber of the air mattress,
at least one inlet connecting the manifold chamber to the pump
outlet; a dump channel providing a connection between the manifold
chamber and the pump inlet, wherein during a powered dumping
operation, the dump channel is configured to receive gas from the
at least one chamber of the air mattress and send the gas to the
pump inlet; a plurality of valves adapted for controlling the flow
of gas between the pump, the manifold chamber, and the at least one
chamber of the air mattress; and a control unit for controlling the
pump and valves.
[0010] In another embodiment, a method for utilizing a pump to
remove gas from at least one chamber of an air mattress is
provided. The method includes: connecting, by opening a valve, the
at least one chamber to a pump inlet of the pump via a dump
channel, wherein the at least one chamber is isolated from a pump
outlet of the pump; opening an exhaust valve to connect the pump
outlet to an exhaust; and operating the pump so as to draw gas from
the at least one chamber to the pump inlet and impel the gas from
the pump inlet and out of the pump outlet to the exhaust.
[0011] In yet another embodiment, a method for utilizing a
boundary-layer pump having at least two sets of disks corresponding
to at least two pressure recovery chambers to fill and dump gas
from at least one chamber of an air mattress is provided. The
method includes: receiving an input from a user of the
boundary-layer pump; adjusting valves based on whether the input
corresponds to at least one of a filling operation, a powered
dumping operation, and a simultaneous filling and powered dumping
operation; and rotating the at least two sets of disks
simultaneously to impel gas from inlets corresponding to the at
least two pressure recovery chambers to outlets corresponding to
the at least two pressure recovery chambers.
[0012] In yet another embodiment, a system for utilizing a pump to
inflate and deflate an air mattress is provided. The system
includes: an air mattress with at least one chamber; a pump adapted
to receive a gas through a pump inlet and impel the gas through a
pump outlet during a filling operation and adapted to receive a gas
through the pump outlet and impel the gas out of an exhaust during
a powered dump operation; and a manifold chamber including at least
one outlet connecting the manifold to the at least one chamber of
the air mattress, at least one inlet connecting the manifold to the
pump outlet; a plurality of valves adapted for controlling the flow
of gas between the pump, the manifold chamber, and the at least one
chamber of the air mattress; and a control unit for controlling the
pump, including the adjustable component of the pump, and the
valves. The pump includes an adjustable component having at least
two settings corresponding to the filling operation and the powered
dumping operation, and the adjustable component isolates a pressure
recovery chamber of the pump from the exhaust during the filling
operation.
[0013] Other aspects and advantages of the invention will become
apparent upon reading the following detailed description and upon
reference to the drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0014] While the appended claims set forth the features of the
present invention with particularity, the invention, together with
its objects and advantages, may be best understood from the
following detailed description taken in conjunction with the
accompanying drawings of which:
[0015] FIG. 1 is a block diagram of an airbed environment useable
in embodiments of the described principles;
[0016] FIG. 2 is a three-dimensional (3D) schematic of an outside
view of a pump;
[0017] FIG. 3 is a schematic of a cross-sectional view of the pump
depicted in FIG. 2;
[0018] FIG. 4 is a schematic of a semi-transparent top-down view of
the pump depicted in FIG. 2 from the pump inlet and motor side;
[0019] FIG. 5 is a 3D schematic of an exploded view of the
components of the pump depicted in FIG. 2;
[0020] FIG. 6 is a simple vector diagram illustrating the velocity
imparted to gas passing through a disk inlet hole by the rotation
of the disk;
[0021] FIGS. 7A and 7B are 3D schematics of outside views of a
pump;
[0022] FIG. 8 is a schematic of a cross-sectional view of the pump
depicted in FIGS. 7A and 7B;
[0023] FIG. 9 is a schematic of a semi-transparent top-down view of
the pump depicted in FIGS. 7A and 7B from the pump inlet side;
[0024] FIG. 10 is a 3D schematic of an exploded view of the
components of the pump depicted in FIGS. 7A and 7B;
[0025] FIGS. 11A and 11B are diagrams showing a simplified set of
disks and a pressure recovery involute illustrating the dimensions
used in performing iterative calculations to determine the geometry
of the disk inlet holes and the pressure recovery involute;
[0026] FIGS. 12A and 12B are simplified diagrams illustrating two
exemplary disk array geometries;
[0027] FIG. 13 is a graph showing the results of experimental
trials estimating the performance of a boundary-layer pump design
relative to commercially available pumps;
[0028] FIGS. 14A and 14B are cross-sectional views of a pump with a
pivot plug configured to perform filling operation and powered
dumping, respectively;
[0029] FIGS. 15A and 15B are 3D schematics of exploded views of a
pump with an adjustable sheath configured to perform filling
operation and powered dumping, respectively;
[0030] FIGS. 15C and 15D are cross-sectional views of the pump
depicted in FIGS. 15A and 15B;
[0031] FIGS. 16A and 16B are 3D schematics of exploded views of
another pump with an adjustable sheath configured to perform
filling operation and powered dumping, respectively; and
[0032] FIGS. 16C and 16D are cross-sectional views of the pump
depicted in FIGS. 16A and 16B;
[0033] FIG. 17 is a block diagram of another airbed environment
useable in embodiments of the described principles;
[0034] FIG. 18 is a schematic of a cross-sectional view of an
integrated pump and manifold capable of powered dumping, with
arrows showing the direction of airflow during filling
operation;
[0035] FIG. 19 is a schematic of a cross-sectional view of the
integrated pump and manifold capable of powered dumping, with
arrows showing the direction of airflow during dumping operation,
according to an embodiment of the described principles;
[0036] FIG. 20 is a schematic of a cross-sectional view of an
integrated pump and manifold with two sets of disks capable of
compounding flow and powered dumping, with arrows showing the
direction of airflow during filling operation of the pump
system;
[0037] FIG. 21 is a schematic of a cross-sectional view of an
integrated pump and manifold with two sets of disks capable of
simultaneously filling certain chambers while performing powered
dumping of other chambers, with arrows showing the direction of
airflow;
[0038] FIG. 22 is a schematic of a cross-sectional view of an
integrated pump and manifold with two sets of disks capable of
compounding pressure or flow and capable of powered dumping, with
arrows showing the direction of airflow during filling operation of
the pump system with compounded pressure;
[0039] FIG. 23 is a schematic of a cross-sectional view of an
integrated pump and manifold with two dissimilarly sized sets of
disks that are matched for pressure compounding, capable of
pressure or flow compounding and capable of powered dumping, with
arrows showing the direction of airflow during filling operation of
the pump system with finely tuned compounded pressure;
[0040] FIG. 24 is a schematic of a cross-sectional view of an
integrated pump and manifold with two sets of disks capable of
compounding pressure or flow and capable of powered dumping,
further capable of simultaneously filling certain chambers while
performing powered dumping of other chambers, with arrows showing
the direction of airflow during filling operation of the pump
system with compounded pressure;
[0041] FIG. 25 is a schematic of a cross-sectional view of the
integrated pump and manifold of FIG. 24, with arrows showing the
direction of airflow during simultaneous dumping of the left side
and filling of the right side;
[0042] FIG. 26 is a schematic of a cross-sectional view of the
integrated pump and manifold of FIG. 24, with arrows showing the
direction of airflow during simultaneous dumping of the left side
and filling of the right side, wherein the gas being dumped from
one side is used to fill the other side;
[0043] FIG. 27 is a schematic of a cross-sectional view of an
integrated pump and manifold capable of powered dumping, with
arrows showing the direction of airflow during filling
operation;
[0044] FIG. 28 is a schematic of a cross-sectional view of the
integrated pump and manifold depicted in FIG. 27, with arrows
showing the direction of airflow during powered dumping
operation;
[0045] FIG. 29 is a schematic of a cross-sectional view of an
integrated pump and manifold with two sets of disks capable of
compounding flow and capable of powered dumping, with arrows
showing the direction of airflow during simultaneous dumping of the
left side and filling of the right side, wherein the gas being
dumped from one side is used to fill the other side;
[0046] FIG. 30 is a schematic of a cross-sectional view of three
pressure recovery stages of a multi-stage disk array configuration,
including two annular pressure recovery stages; and
[0047] FIG. 31 is a schematic of a cross-sectional view of an
integrated pump and manifold capable of powered dumping, utilizing
the multi-stage disk array configuration shown in FIG. 30, with
arrows showing the direction of airflow during filling
operation.
DETAILED DESCRIPTION
[0048] An exemplary airbed environment 100 in which the invention
may operate is depicted by FIG. 1. It will be appreciated that the
described environment is an example, and does not imply any
limitation regarding the use of other environments to practice the
invention. The airbed environment 100 includes a control housing
110 and an air mattress 120. The control housing further includes a
control unit 114 and a pump 111, wherein the pump 111 is connected
to chambers A 121 and B 122 via an appropriate connection. For
example, in FIG. 1, the pump 111 may be connected to the chambers
through tubes 113, 115 and 116 and a manifold 112, along with
appropriate valves (not depicted). The tubes may be PVC (Polyvinyl
Chloride) or silicone rubber or any other appropriate connections
for transferring a gas, such as air, from a pump outlet to air
mattress chambers. The manifold 112 may be manufactured out of
thermoplastic or any other suitable type of material with
sufficient mechanical strength to contain the amount of pressure
required. For example, for applications requiring about 1 psi of
air, materials such as ABS (Acrylonitrile Butadiene Styrene), PP
(Polypropylene), PC (Polycarbonate), or PPE (Polyphenylene Ether),
may be used. One skilled in the art will appreciate that the type
of material used may vary depending on the pressure requirements of
the particular application (e.g. a properly designed PPE manifold
may withstand up to several hundred psi).
[0049] Valves are provided at appropriate locations, for example,
at the connection between the manifold 112 and the tubes 113, 115,
and 116, and the valves may be in communication with the control
unit 114. Solenoid plunger style valves may be preferable due to
their electromechanical control capabilities and relatively low
cost, but it will be appreciated that other types of valves may be
used. A pressure sensor or multiple pressure sensors (not depicted)
may be connected to the manifold or valves to monitor the pressure
status of the chambers, and the pressure sensor or sensors
communicate with the control unit 114, providing the control unit
114 with pressure information corresponding to the manifold or the
air mattress chambers.
[0050] The control unit 114 preferably includes a printed circuit
board assembly (PCBA) with a tangible computer-readable medium with
electronically-executable instructions thereon (e.g. RAM, ROM,
PROM, volatile, nonvolatile, or other electronic memory mechanism),
and a corresponding processor for executing those instructions. The
control unit 114 controls the pump 111 and the flow of gas in the
airbed environment through the tubes 113, 115, and 116 by opening
and closing the appropriate valves. The control unit 114 may
further send and receive data to and from a user remote 130,
allowing a user of the airbed environment 100 to control the
pumping of the air mattress 120 through the control unit 114, as
well as displaying information related to the airbed environment
100 to the user. For example, an exemplary remote 130 includes a
display that indicates the current pressure status of the chambers
of the air mattress 120 or the current pressure target for the
chambers, and also includes input buttons that allow the user to
communicate the user's desired pressure settings to the control
unit 114. The user remote 130 may be connected to the control unit
114 through a wired connection as depicted, or may communicate with
the control unit 114 wirelessly through appropriate communications
hardware.
[0051] It will be appreciated that the airbed environment 100 is
merely exemplary and that the principles described herein are not
limited to the environment 100 depicted. For example, it will be
appreciated that in an alternative embodiment, a mattress 120 with
only one chamber may be used. In other embodiments, a mattress 120
with more than two chambers may be provided, with the appropriate
number of connections to those mattresses. In yet another
alternative embodiment, the manifold 112 may be connected directly
to the pump outlet without the use of a tube 113, and in yet
another alternative embodiment, the manifold 112 may be located
inside the mattress 120 instead of within the control housing
110.
[0052] With further reference to the environment of FIG. 1, and
turning more specifically to FIG. 2, an outside view of an
exemplary boundary-layer pump 200 used in an illustrative
embodiment of the described principles is shown. The pump 200
includes a pressure recovery chamber housing, which further
includes a pressure recovery chamber housing cover 210 and a
pressure recovery chamber housing body 211. A pump inlet 212 is
provided on the pressure recovery chamber housing cover 210, and a
pump outlet 213 is provided on the pressure recovery chamber
housing body 211. The pressure recovery chamber housing body 211
and cover 210 may be made from materials including, but not limited
to, plywood, MDF (medium density fibreboard), phenolic, HDPE (high
density polyethylene), mahogany, PC, and acrylic.
[0053] A motor 220 is attached to the pressure recovery chamber
housing cover 210 by motor standoff rods 221, though it will be
appreciated that motor standoff rods 221 are not a requirement. The
motor 220 may preferably be a brushed or brushless DC (direct
current) motor, or any other type of motor that generates a
sufficient amount of RPMs. In one embodiment, for example, a Himax
HC2812-1080 KV motor may be used with a Castle Creations, Inc.
Phoenix ICE 50 or Thunderbird 18 motor controller.
[0054] FIG. 3 provides one cross-sectional view of the exemplary
boundary-layer pump 200 along cross-sectional line A-A' of FIG. 2.
The shaft of the motor 220 is connected to another shaft 232, which
is an arbor adapted to hold the disks 230. The arbor traverses
holes at the centers of the disks 230, and is designed to hold the
disks 230 in predetermined locations along the arbor. The
predetermined locations are depicted as substantially evenly spaced
along the arbor, but it will be appreciated that this is not a
requirement. Varying the spacing of the disks, unless taken to an
extreme, does not significantly affect the performance of the
boundary-layer pump 200 in comparison to the other parameters
discussed below. The disks 230 have holes at the center of the
disks that the shaft 232 traverses. The holes may differ in size
and shape according to the shape of the shaft 232. In specific
embodiments, the disks may be made from materials including, but
not limited to, 0.032'' 2024T3 Aluminum, 0.063'' Polycarbonate, or
conventional compact discs (CDs), and the arbor may be machined
from materials including, but not limited to, 304 Stainless Steel
or 4130 Steel. In an alternative embodiment, the shaft 232 and the
disks 230 may be designed as one continuous piece through an
injection-molding process, and would not require holes to be
present at the center of the disks.
[0055] The disks 230 and at least part of the shaft 232 are within
pressure recovery chamber 240, and the shaft 232 is connected to a
bottom bearing 233 and a nut 234 at the opposite end from the motor
220. The disk furthest away from the pump inlet 212 is designed
with no disk inlets (this disk is called the "base disk"). Allowing
gas to travel through the base disk would result in inefficiencies
due to the viscous adhesion forces that would be introduced along
the adjacent wall of the pressure recovery chamber, causing an
increased amount of gas recirculation. A gas, which may be a
homogenous or non-homogenous non-compressible fluid (e.g. ambient
air), enters through the pump inlet 212 and passes through the disk
inlets 231, and is drawn radially outwards from the disk inlets 231
towards the edges of the disks 231 due to the rotation of the disks
231 while the motor 220 rotates the shaft 232. The path traveled by
the gas (through the pump inlets and disk inlets, and radially
outward along the disks into the pressure recovery chamber and
towards the pump outlet) is indicated in FIG. 3 by the bold arrows
labeled AIR FLOW.
[0056] FIG. 4 provides a semi-transparent top-down view of the
boundary-layer pump 200 from the side of the boundary-layer pump
200 having the motor 220 and pump inlet 212. As described above,
gas enters the pump 200 through the pump inlet 212 and passes
through disk inlets 231. The rotation of the disks in the direction
depicted by the arrow marked DISK ROTATION causes the gas to flow
radially outward along the disks 230. Gas is flung off of the disks
230 according to the velocity vector associated with the gas at the
edges of the disks and is compressed in the pressure recovery
involute (the area between the edge of the disks and the edge of
the pressure recovery chamber 240) as it ultimately travels towards
the pump outlet 213. An example of how gas may flow through the
pump 200 is indicated by the bold arrows labeled AIR FLOW.
[0057] FIG. 5 provides a 3D schematic of an exploded view of the
components of the boundary-layer pump 200. The motor 220, standoff
rods 221, pump inlet 212, pressure recovery chamber housing cover
210, shaft 232, disks 230, disk inlet holes 231, nut 234, bearing
233, pressure recovery chamber 240, pressure recovery chamber
housing body 211, pump outlet 213, and the order in which these
components are arranged in one embodiment are depicted. Although
FIGS. 2-5 depict the motor 220 positioned near the pump inlet 212,
it will be appreciated that the motor 220 may be positioned on the
other side of the pressure recovery chamber housing as well.
[0058] The pump 200 is referred to as a boundary-layer pump because
it employs the boundary-layer effect on air surrounding spinning
disks in the pump to transfer energy from the spinning disks to the
air. Air, which is drawn into the pump inlet 212 due to a region of
low pressure produced by the rotation of the disks 230, enters
through the inlet holes 231 on the disks 230 and is subject to
viscous boundary layer adhesion forces that impart a velocity
profile including a centrifugal component and a radial component,
as depicted by FIG. 6. The air within the boundary layer created by
the rotation of the disks works it way outwards in a spiral path
with the velocity profile increasing in magnitude as the air
travels outward. When the air reaches the edge of the spinning
disks, it is flung off of the disks and compressed against the
walls of the pressure recovery chamber. The air is flung off of the
disks at an angle according to the resultant velocity vector
imparted to the air as depicted by FIG. 6. The rotation speed of
the disks strongly influences the angle and magnitude of the
resultant velocity vector shown in FIG. 6. The area between the
edges of the disks and the walls of the pressure recovery chamber
may be referred to as the pressure recovery involute, which may be
shaped in a spiral as depicted in FIG. 4. After being flung off of
the edges of the disks, the air travels towards the pump outlet
along the pressure recovery involute and is further compressed by
additional air being impelled off of the disks along the way and
the expansion of the involute decelerating the air.
[0059] It will be appreciated that the present invention is not
limited to the embodiments depicted in the drawings, and that the
configuration of the pump 200 and the airbed environment 100 may be
varied while remaining within the scope of the described
principles. For example, the number and shape of the disks and the
disk inlets may be varied, and although nine disks with six disk
inlet holes are depicted in FIG. 5, the number and shape of the
disks and the disk inlet holes may be varied. Another example is
the configuration of the pressure recovery chamber housing, which
does not necessarily require the two-piece cover and body
configuration depicted, and which does not require the pump inlet
and motor to be on the cover side while the pump outlet is on the
body.
[0060] In further embodiments, portions of the pressure recovery
chamber may be sealed or partially sealed off from each other to
prevent gas recirculation within the pressure recovery chamber. By
decreasing the amount of gas being recirculated within the pressure
recovery chamber, the efficiency of the pump can be increased (e.g.
achieving same amounts of flow and pressure with lower RPMs, less
noise, and less power). One channel through which air recirculation
occurs can be seen in FIG. 3, where gas flowing towards the outlet
may recirculate through the space between the pressure recovery
chamber housing cover 210 and the top disk of disks 230. One way of
inhibiting this gas recirculation is to mount the motor 220 on the
opposite side of the pressure recovery chamber, which would allow a
ring to be raised up off the top disk and to be sleeved into an
inlet bore, creating a conventional shaft and bore style seal. This
design has the added benefit of reducing blockage of the inlet area
caused by the arbor occupying space at the pump inlet 212, and
further reduces the required size of the inlet hole, which allows a
smaller seal to be used around the outside of the inlet hole.
Another channel of gas recirculation can be seen in FIG. 4, where
gas flowing near the pump outlet 213 may recirculate through the
narrowest part of the pressure recovery involute and back around
the pressure recovery chamber 240. Beyond constraining the distance
between the edges of the disks and the pressure recovery chamber
240 at that point to a minimum (e.g. about 0.01''-0.02''), a
sealing flap, such as a flap made out of Teflon, may be placed
between the wall of the pressure recovery chamber 240 and the edges
of the disks 230 to block the gas from recirculating.
[0061] With further reference to the environment of FIG. 1, and
turning more specifically to FIGS. 7A and 7B, outside views of
another exemplary boundary-layer pump 700 used in another
illustrative embodiment of the described principles are shown. The
pump 700 includes a pressure recovery chamber housing, which
further includes a pressure recovery chamber housing cover 710 and
a pressure recovery chamber housing body 711. A pump inlet 712,
which is bellmouth-shaped for improved gas intake rate, is provided
on the pressure recovery chamber housing body 711, and a pump
outlet 713 is provided on the pressure recovery chamber housing
body 711. A motor 720 is attached to the pressure recovery chamber
housing cover 710. It will be appreciated that motor standoff rods
are not used in this exemplary embodiment. It will also be
appreciated that placing the motor 720 on the side opposite from
the pump inlet prevents the motor 720 from obstructing air flow
through the pump inlet 712. FIG. 7B further depicts several
attachment points 701 where, for example, screws can be placed to
attach the pressure recovery chamber housing cover 710 to the
pressure recovery chamber housing body 711.
[0062] FIG. 8 provides a cross-sectional view of the boundary-layer
pump 700 along cross-sectional lines B-B' depicted in FIG. 7B. The
motor 720 is connected to a disk assembly collet 811, which,
together with collet nut 812, holds a base disk 801 that is
furthest away from the pump inlet 712 in place. A disk
array--including disks 730 and a "top" disk 802 (i.e., farthest
from the base disk 801)--is attached to the base disk 801 by way of
several disk retention pins 750 (for simplicity, only one disk
retention pin 750 is depicted in FIG. 8), which will be explained
in further detail with respect to FIG. 10. These pins cause the
disk array to spin together with the base disk 801, which is spun
by the motor 720 in combination with the disk assembly collet 811
and collet nut 812. It will be appreciated that, as shown in FIG.
8, the shape of the collet nut and uniform circular disk inlet
areas 731 creates a tapered flow channel which reduces in area
(from top disk 802 to base disk 801). This reduction in flow area
provides a relatively more uniform flow speed through the disk
array as each disk draws off an amount of air to compress. In an
alternative embodiment, the base disk 801 and the disk array
including disks 730 and top disk 802 are sonic-welded or otherwise
bonded directly to a shaft of a motor 720, which would eliminate
the need for a collet assembly. It will be appreciated that, in
this alternative embodiment, the geometry of the disks would be
appropriately modified to allow such welding or bonding.
[0063] In one embodiment, the top disk 802 is identical to the
other disks 730. In another embodiment, the top disk 802 has a ring
raised off of it which is sleeved into an inlet bore, creating a
conventional shaft and bore style seal that reduces recirculation
of gas flowing towards the pump outlet 713 going over the top of
the top disk 802 and back towards the pump inlet 712. In yet
another further embodiment, all of the disks of the disk array have
different sized disk inlet areas 731. For example, in an embodiment
where the base disk 801 and the disk array are bonded directly to a
motor shaft, the disk inlet areas 731 are configured such that
there is a reduction in inlet hole area moving from the top disk
802 to the base disk 801, so as to achieve a tapered flow channel
through the disk array (e.g., as depicted in FIGS. 12A-B
below).
[0064] When the pump 700 is operated and the motor 720 is spinning,
gas enters through the pump inlet 712, travels through a disk inlet
area 731 on each disk in the disk array while also being drawn
radially outwards along the disks into the pressure recovery
chamber 740 and towards the pump outlet 713. For optimal
performance, the motor 720 should be balanced with respect to the
base disk 801 and the attached disk array. One exemplary way to
balance the motor with the base disk 801 and the disk array is to
selectively remove material from the base disk 801.
[0065] FIG. 9 provides a semi-transparent top-down view of the
boundary-layer pump 700 from the side of the boundary-layer pump
700 having the pump inlet 712. FIG. 9 shows the relative sizes of
the disks 730, pump inlet 712, disk inlet areas 731, and the collet
nut 812. The space between the disks 730 and the walls of the
pressure recovery chamber 740 form an involute shape that widens as
it approaches the pump outlet 713. The pump inlet 712 has a
bellmouth shape, the outer circumference of which is shown in FIG.
9. The tapered flow channel of the pump 700 is defined by the disk
inlet areas 731 and the collet nut 812 as described above.
[0066] FIG. 10 provides a 3D schematic of an exploded view of the
components of the boundary-layer pump 700. The motor 720, pressure
recovery chamber housing cover 710, disk assembly collet 811, base
disk 801, collet nut 812, disks 730, top disk 802, disk retention
pins 750, pressure recovery chamber housing body 711, pump outlet
713, and the order in which these components are arranged in one
embodiment are depicted. It will be appreciated that the disk
retention pins 750 correspond to holes in the disks 730, closest
disk 802, and base disk 801 and serve to hold the disk array to the
base disk 801 and to transmit torque to the disk array. The disk
retention pins, for example, may be glued to the disks or, in
another example, may be replaced by a series of molded posts and
receivers that are sonic welded together in creating the disk array
and base disk.
[0067] The principles of gas flow through the pump 700 shown in
FIGS. 7-10 are similar to those described above with respect to the
pump 200 with respect to FIGS. 2-6. Gas enters through the pump
inlet 712, travels through and along the disks of the disk array
into an involute-shaped pressure recovery chamber 740, and goes out
through the pump outlet 713.
[0068] Although pumps utilizing boundary-layer effects, also known
as Tesla pumps, may be known to those familiar in the field of
fluid mechanics and pumping technologies, these types of pumps have
conventionally only been commercially implemented in large-scale
liquid pumping applications, at least in part because Tesla pumps
are not prone to the cavitation problems experienced with other
types of liquid pumps (an advantage that is inapplicable to the
pumping of a gas). The drastic difference between the viscosities
of liquids and gases, which is on the scale of two orders of
magnitude (at 20.degree. C., air has a kinetic viscosity of 1.83E-5
Pa-s while water has a kinetic viscosity of 1.00E-3 Pa-s), and the
size constraints inherent to an airbed environment (liquid pumps
often use disks with diameters of at least 12-18 inches, which
would be too large to be commercially feasible for airbed
applications) introduce serious complications into the design of a
boundary-layer pump for an airbed environment. Furthermore, the
relatively low pressures used in airbed environments require
precise pressure control.
[0069] Given a relatively small disk size (e.g. approximately 3.7
inch diameter in one embodiment), the number of revolutions per
minute (RPMs) has to be very large to generate the amount of flow
and pressure desired in an airbed environment (e.g. approximately
around 21,000 RPMS in one embodiment). Introducing such a high
number of RPMs introduces vibration and longevity issues, as the
boundary-layer pump loses efficiency and generates noise due to the
vibrations, and the components of the pump affected by the high
RPMs (such as the bearing at the end of the shaft) are subject to
wear-and-tear considerations. The performance of the boundary-layer
pump in the airbed environment is further sensitive to the
relationship between the disk diameter, number of disks, operable
range of RPMs and the shape/curvature of the pressure recovery
involute. Furthermore, for best performance, the shape of the
pressure recovery involute should be carefully matched to the disk
diameter, disk quantity and operating RPM of the boundary-layer
pump.
[0070] To determine an efficient geometry for the disk inlet holes
and the pressure recovery involute, an iterative calculation based
on Bernoulli's equation may be performed. While Bernoulli's
equation has certain limitations which must be taken into
consideration, it is very useful for certain aspects of disk sizing
and determining the geometry of the pressure recovery chamber. It
becomes less accurate at relatively high flow rates and pressures
when compressibility effects are more significant, but it is still
useful as a starting point in an iterative process of calculating
how large the inlet area on the disks should be. Bernoulli's
equation--which assumes (1) laminar flow (non-turbulent), (2)
adiabatic flow (no heat transfer), (3) ideal inviscid behavior (no
internal heat generation), (4) incompressibility (generally true
for flow velocities less than Mach 0.3), (5) a stream line (looking
at same "particle" of fluid in two locations), and (6) constant
gravity field--is provided by the following mathematical
relationship:
v 2 2 + gz + p .rho. = constant ##EQU00001##
[0071] where .nu. is the fluid flow speed at a point on the
streamline, g is the acceleration due to gravity, z is the
elevation of the point above a reference plane, with the positive
z-direction pointing upward, p is the pressure at the chosen point,
and .rho. is the density of the fluid at all points of the fluid.
In the context of two different stations, by setting the two
stations equal to one another (continuity) and adding the equation
for flow rate (Q),
{ Q = v 1 A 1 = v 2 A 2 p 1 - p 2 = p 2 ( v 2 2 - v 1 2 ) , Q = A 1
2 ( p 1 - p 2 ) .rho. ( ( A 1 A 2 ) 2 - 1 ) = A 2 2 ( p 1 - p 2 )
.rho. ( 1 - ( A 2 A 1 ) 2 ) . ##EQU00002##
and then further incorporating the energy increase provided by the
disk array to the original statement of Bernoulli's equation,
p.sub.in/.rho.+v.sub.in.sup.2/2+gz.sub.in+w.sub.shaft=p.sub.out/.rho.+v.-
sub.out.sup.2/2+gz.sub.out+w.sub.loss
where w.sub.shaft is the net shaft energy in per unit mass and
w.sub.loss is the loss due to friction, a useful system of
equations may be obtained with which to iteratively solve for an
appropriate size of the inlet hole and geometry of the pressure
recovery chamber. It will be appreciated that, to simplify the
calculation, the loss due to friction may be ignored, which may
produce some deviation between theoretical and actual results.
[0072] An iterative process that may be used is as follows:
[0073] (1) A target flow rate (Q) may be chosen based on design
requirements and a first station, "station 1" may be set as the
inlet to the pump and a second station, "station 2," may be set as
the exit to the pressure recovery involute.
[0074] (2) A starting pressure and compression ratio are estimated
to calculate p.sub.out. For example, the starting pressure may be
assumed to be at atmospheric, and a value such as 1.14 may be
chosen as an estimation of the compression ratio achieved by the
disk array. It will be appreciated that, depending on the design of
the disk array and RPM, a wide range of compression ratios may be
possible.
[0075] (3) The power added to the system via the motor may be
measured experimentally or calculated based upon the expect Q,
p2/p1, and assumed efficiency of the Tesla array. For example, 60%
is a generally accepted number for Tesla pump efficiency.
[0076] (4) Using conventional performance equations and charts
found in references such as Karassik et al., "Pump Handbook,"
McGraw-Hill (2001) (see Chapter 2 and FIGS. 8, 12 and 20), which is
hereby incorporated by reference in its entirety entireties, the Q,
p2/p1, fluid density and input power may be used to look up the
recommended final A2 area of the involute. However, given that the
performance charts are based on pump designs that are significantly
larger than what would be suitable for the airbed industry, the
values given by the tables may be extrapolated to arrive at an
estimation more suitable for relatively small pump designs. A
better reference that may be used is Ametek Technical &
Industrial Products, "A: Low Voltage Brushless DC Blowers," Ametek
Products Catalog: Blowers (see "3.0 (76 mm) BLDC Low-Voltage
Blower"), available at
http://www.ametektip.com/index.php?option=com_catalog&view=catalog,
which is incorporated herein by reference in its entirety, which
pertains to pump designs that are smaller than those described by
Karassik et al. Using the performance chart from a reference such
as the Ametek catalog thus provides a closer starting point for
subsequent estimations and calculations.
[0077] (5) Using Q, p1, p2, A2, and input power, A1 may be
calculated using Bernoulli's equation, where A1 is the minimum area
for the holes down the middle of the disks.
[0078] (6) Using A1, a minimum cumulative area at the inlet to the
gaps between the disks may be determined as shown in diagram 1100B
of FIG. 11B. For example, in a single center hole design, A1 may be
used to give the diameter D.sub.1 of the center hole. The
circumference of the center hole may then be multiplied by the gap
height between the disks and the number of disks to provide the
cumulative area A3 at the inlet to the gaps between the disks. For
example, for a disk array design with uniform disk inlet area with
three gaps between disks as shown in diagram 1100A of FIG. 11A,
A3=D.sub.1.pi..times.h.sub.2.times.3. This cumulative area A3
should be slightly greater than or equal to A1.
[0079] In certain embodiments, the disks may have a tapered hole
style layout as shown in diagram 1200B of FIG. 12B. With a tapered
hole style layout, the calculation proceeds on a disk-by-disk
basis, with the net area of each gap subtracted from the area of
the hole in the gap's "ceiling" disk. The reduced area is used to
calculate the required area of the hole in the gap's "floor" disk.
By repeating this process until the inlet hole in the "ceiling"
disk is roughly equal to the inlet gap area in the last disk. For
example:
D 1 .pi. .times. h 2 .apprxeq. ( D 1 2 4 .pi. - D 2 2 4 .pi. ) and
D 2 .pi. .times. h 2 .apprxeq. ( D 2 2 4 .pi. - D 3 2 4 .pi. )
##EQU00003##
and so on.
[0080] Another alternative design is shown in diagram 1200A of FIG.
12A, which is similar to the disk array layout of the
boundary-layer pump 700 discussed above with respect to FIGS.
7A-10. The layout shown in FIG. 12A effectively achieves the same
result as the layout shown in FIG. 12B, but the layout shown in
FIG. 12A provides certain advantages with respect to ease of
manufacture and helping to induce radial flow. It will be
appreciated that in FIGS. 11A-B and 12A-B, the simplified depiction
of the cross-section of the disks omits the shaft and the parts of
the disks connected to the shaft.
[0081] (7) Finally, using the summed disk and gap heights and A2,
the maximum gap W.sub.2 between the involute and the disk array may
be calculated as shown in FIG. 11A. It will be appreciated that, as
this is an iterative process involving estimations, one skilled in
the art would be able to reach a variety of values for the set of
parameters (A1, D.sub.1, h.sub.2, W.sub.2, etc.) defining the
geometry of the pressure recovery involute and the disk arrays in
accordance with the principles described herein.
[0082] It will also be appreciated that the calculations above are
based on an assumption that the flow rates do not exceed about Mach
0.3 to Mach 0.5. However, it will be appreciated that even though
the quality of prediction decreases at higher speeds, the
calculations above may still be used for a first pass sizing
estimation for the pump dimensions. In any event, accurately
predicting the behavior of such boundary-layer pump designs,
whether at relatively low or relatively higher speeds, generally
requires some degree of iterative testing using physical models. To
give an example, at 21 k RPM, a 3.7'' diameter disk's perimeter is
moving at Mach 0.3. In actual experiments with 3.7'' disks rotating
at 21 k RPM, the calculations described above were determined to
work well for predicting actual performance (within about 15% of
theoretical results) and for predicting design changes that improve
actual performance.
[0083] As mentioned above, various disk designs may be used in
embodiments of the present invention, ranging from relatively
simple single-sized center hole designs as shown in FIGS. 11A-B and
tapered hole designs shown in FIGS. 12A-B, to more complex disk
designs such as disks with overall tapering (i.e. disks with
overall different diameters). In further embodiments, the surface
texture of the disks may also be varied (e.g., disks having smooth
surfaces versus disks with embedded splines or waves). For example,
the roughness of a disk is a significant variable in terms of
increasing flow at relatively low pressures. At a given number RPMs
and back pressure, a smooth disk, such as a CD (Ra=12), produces
more flow than a rougher disk with 100 grit sandpaper glued to its
surface (Ra=150), while the rougher disk generates more pressure.
However, this effect diminishes as the flow rate approaches
zero.
[0084] Thus, the design of boundary-layer pumps in the airbed
environment requires a large number of unique considerations: the
extremely low viscosity of air, the size constraints of an airbed
environment, the pressure and flow required for an air mattress,
the RPMs and disk size necessary to achieve those requirements, the
effect of the required RPMs on the pump components, and the
relationship between the radial velocity of the impelled air and
the shape of the pressure recovery chamber. It will be appreciated
that variables such as disk size, spacing, texture, number, and
speed may be put together in multiple offsetting ways (e.g., more
disks with smaller disk size versus less disks of a bigger disk
size) to achieve a configuration that is appropriate for airbed
applications.
[0085] In one trial involving an embodiment that used ten 3.7 inch
diameter disks and the pressure recovery involute shape depicted in
FIG. 4, a boundary-layer pump operating at about 21,000 RPMs on
about 80 Watts of power was able to output approximately 0.83 psi
and more than 100 L/min in flow. A conventional squirrel-cage
blower tested under the same conditions produced 20-30% less
pressure and much less flow. In other trials involving a comparison
of an implementation of boundary-layer pump 700 depicted in FIGS.
7-10 to commercially available pumps, the boundary-layer pump 700
was also shown to outperform those commercially available pumps
with respect to target flow rates and pressures for airbed
applications.
[0086] Further, FIG. 13 is a graph 1300 depicting an estimated
comparison between boundary-layer pump designs and commercially
available pumps. The Ametek 150914-50 is an expensive high-end
squirrel cage blower. The Thomas 6025SE and Hailea AP-45 are
dual-acting diaphragms pumps. As can be seen from graph 1300, the
boundary layer pumps are able to achieve much higher flow rates at
target pressures suitable for airbeds (e.g., approximately from 0.1
to 1.5 psi). The estimated comparison was based on several trials
involving power-limited motors (to compare the efficiency of each
design, the same power-limited motor was used in each pump tested),
and the graph 1300 is intended to show a performance envelope that
is possible for a boundary-layer pump using only a single disk
array to show that such a performance envelope is not possible for
commercially available pumps using the same motor. The flow rate
axis is governed by the amount of power available (and also the
number of discs for a boundary-layer pump design). Thus, it will be
appreciated that the graph 1300 shows that, when using a motor of
the same power, the boundary layer pump outperforms
commercially-available pumps, and that at different motor power
values, the values shown in the graphs may change (but the
boundary-layer pump is expected to outperform the
commercially-available pumps at other motor power values as
well).
[0087] In further embodiments, the previously described
boundary-layer pumps are modified so as to be capable of performing
a powered dump operation. Conventionally, when a user wishes to
reduce the pressure in an air mattress, the control unit opens and
closes valves such that the appropriate air mattress chamber or
chambers is or are connected to an exhaust that vents out gas from
the air mattress. During this venting, the pump remains off.
However, with a powered dump operation, the described
boundary-layer pumps are modified such that the pumps are turned on
and used to decrease the pressure in the appropriate air mattress
chamber or chambers more quickly (relative to venting).
[0088] FIGS. 14A and 14B depict an exemplary boundary-layer pump
1400 capable of powered dump. The boundary-layer pump 1400 is
similar to the boundary-layer pump 700 depicted in FIGS. 7-10. The
direction of rotation of the shaft and disks can be reversed, for
example, by reversing the polarity of the electric current being
supplied to the motor, with rotation in one direction (as depicted
in FIG. 14A) corresponding to filling operation and rotation in the
other direction (as depicted in FIG. 14B) corresponding to powered
dump operation. It will be appreciated that there are other ways of
reversing the direction of operation of the motor, for example, by
adjustment of a brushless motor controller. As shown in FIGS. 14A
and 14B, the pressure recovery housing of pump 1400 includes an
exhaust outlet 1410 in addition to the pump inlet and the pump
outlet. In this embodiment, a pivot plug 1411 is positioned at the
exhaust outlet 1410 such that, in a first position during filling
operation, it forms part of the wall of the pressure recovery
chamber and isolates the pressure recovery chamber from the exhaust
outlet (as shown in FIG. 14A), and, in a second position during
powered dump operation, it is positioned so as to allow gas
entering the pressure recovery chamber to be expelled outwards
through the exhaust outlet 1410.
[0089] It will be appreciated that, during the powered dump
operation, an inlet valve associated with the pump (e.g. a flapper
valve) is closed, preventing gas in the atmosphere from entering
the boundary-layer pump 1400 during the powered dump operation.
When the exhaust outlet 1410 is opened (through the pivot plug 1411
changing positions) and the inlet valve is closed, gas moves from
the relatively high pressure region of the pump outlet into the
pressure recovery chamber. The relatively low pressure region at
the exhaust outlet 1410 combined with the rotation of the disks in
the reverse direction (as shown in FIG. 14B), which imparts a
velocity profile to gas pushed onto the disks by the relatively
high pressure at the pump outlet, causes the gas to move from the
pump outlet to the exhaust outlet 1410 during the powered dump
operation of the boundary-layer pump 1400.
[0090] FIGS. 15A and 15B depict another exemplary boundary-layer
pump 1500 capable of performing a powered dump operation. Pump 1500
is similar to pump 700 of FIGS. 7-10, but with a pump inlet 1312
that is matched to an adjustable sheath 1570. The boundary-layer
pump 1500 also has a reversible motor 1520 and an exhaust outlet
1560. As shown in FIG. 15A, which is an exploded view of the
components of the pump 1500 when the adjustable sheath 1570 is in
position for a filling operation, the adjustable sheath 1570 is
positioned such that the exhaust outlet 1560 is cut off from the
pressure recovery chamber of the pressure recovery housing by the
adjustable sheath 1570, and a window 1571 of the adjustable sheath
1570 is aligned with a similarly-shaped pump inlet 1512. Thus, when
the motor 1520 is operated during filling operation, gas enters
through the pump inlet 1512 and the window 1571, travels along a
pressure recovery involute formed by the pressure recovery chamber
in combination with the adjustable sheath 1570, and exits through
the pump outlet 1513. Another view of the adjustable sheath 1570 in
this position for filling operation is shown in FIG. 15C, which
depicts a cross-section of the pump 1500 during filling operation.
It will be appreciated that the size, shape, and configuration of
the pump inlet 1512 and the window 1571 can be varied. The
depiction of the pump inlet 1512 and the window 1571 in FIGS. 15A-D
are merely exemplary. In other variations, the pump inlet 1512 and
the window 1571 can be larger or smaller, can be a different shape,
or can have a configuration involving multiple inlets and
windows.
[0091] Turning to FIG. 15B, the pump 1500 is shown in a powered
dump operation. In order to perform powered dump operation, the
adjustable sheath 1570 is shifted into a powered dump position
where the sheath 1570 is positioned such that the exhaust outlet
1560 is now exposed to the pressure recovery chamber, and the
window 1571 of the adjustable sheath 1570 is no longer aligned with
the pump inlet 1512, cutting off the pump inlet 1512 from the
pressure recovery chamber. The direction of rotation of the motor
1520 is reversed in the powered dump mode. Thus, gas enters the
pressure recovery chamber from an air mattress through the pump
outlet 1513, is drawn through the pressure recovery chamber
circumferentially by the spinning disk array, and is expelled
through the exhaust outlet 1560. As shown in FIG. 15D, which
depicts a cross-section of the pump 1500 during powered dump
operation, the geometry of the pressure recovery chamber is
reversed during powered dump operation, creating a pressure
recovery involute that widens as it approaches the exhaust outlet
1560.
[0092] It will be appreciated that the pump design shown in FIGS.
15A-D utilizes a reversible motor. In another further embodiment,
another exemplary boundary-layer pump 1600 capable of performing a
powered dump operation with a non-reversible motor is shown in
FIGS. 16A-16D. The boundary-layer pump 1600 is similar to the
boundary-layer pump 1500 depicted in FIGS. 15A-15D and includes a
motor 1620, pump inlet 1612, pump outlet 1613, exhaust 1660,
adjustable sheath 1670, and a window 1671 on the adjustable sheath
1670. However, the motor 1620 is a non-reversible motor and the
exhaust 1660 is positioned differently with respect to the pressure
recovery chamber relative to the design of pump 1500. FIG. 16A is a
schematic of an exploded view of the pump 1600 with the sheath in
position for filling operation, while FIG. 16B is a schematic of an
exploded view of the pump 1600 with the sheath in position for
powered dumping. FIGS. 16C and 16D provide cross-sectional views of
the pump 1600 with the sheath in position for filling operation and
in position for powered dumping, respectively.
[0093] Thus, it will be appreciated that exemplary boundary layer
pumps 1400, 1500, and 1600 are different configurations of
boundary-layer pumps that are able to achieve powered dumping. Each
configuration is suitable for different applications based on cost
and performance requirements, as the differences between each
design represents certain tradeoffs between complexity, cost, and
performance. For example, the boundary-layer pump 1600 depicted in
FIGS. 16A-16D utilizing a non-reversible motor produces slightly
less negative pressure during powered dumping than the
boundary-layer pump 1500 depicted in FIGS. 15A-15D which utilizes a
reversible motor. However, because the boundary-layer pump 1600
uses a non-reversible motor, it also comes with slightly lower cost
and is less complex.
[0094] Furthermore, while FIGS. 14A-16D show various embodiments of
pump-driven configurations for achieving powered dumping, there are
also manifold-driven configurations that allow powered dumping that
will be discussed in further detail below in the context of various
manifold and housing configurations utilizing boundary-layer pump
designs.
[0095] FIG. 17 depicts a variation 1700 of the exemplary airbed
environment 100 from FIG. 1 in which the invention may operate,
wherein the pump and manifold are integrated into a single pump and
manifold housing (hereinafter "integrated housing") 1710. The air
mattress 120 is further depicted with six chambers instead of two
chambers, although it will be appreciated that both environments
100 and 1700 may include an air mattress 120 with any number of
chambers. Appropriate connections between the integrated housing
1710 and the six chambers are shown, with one connecting tube for
each chamber. In another embodiment, instead of having six
connecting points at the integrated housing 1710 (corresponding to
the number of manifold outlets), the integrated housing 1710 may
have a different number, such as four outlets, to accommodate six
chambers. In this embodiment, the tubes connected to two of the
outlets may be divided by a splitter such that one outlet may
service two chambers (e.g. chambers 1 and 4 and chambers 4 and 6
being serviced by the same outlet via a splitter). It will be
appreciated that the integrated housing 1710 of airbed environment
1700 of FIG. 17 and the manifold 112 of airbed environment 100 of
FIG. 1 may be configured with any number of outlets connected to
any number of chambers within an air mattress by appropriate
connections and splitters. It will further be appreciated that an
integrated housing 1710 or manifold 112 with, for example, six
outlets may be used together with an air mattress with, for
example, two chambers, as unused outlets could merely remain
closed. Thus, a single control housing 110 is readily adaptable for
use with a variety of air mattresses.
[0096] FIGS. 18 and 19 provide a cross-sectional view of an
exemplary integrated housing 1800 capable of utilizing the pump to
perform a manifold-driven powered dump of one or more air mattress
chambers (as opposed to the pump-driven powered dump designs
discussed above with respect to FIGS. 14A-16D). FIG. 18 includes
arrows showing the flow of gas while the integrated housing 1800 is
filling an air mattress chamber, and FIG. 19 includes arrows
showing the flow of gas while the integrated housing 1800 is
performing a powered dump of the air mattress chamber. Although two
manifold outlets are depicted in this exemplary embodiment, it will
be appreciated that any number of manifold outlets may be used. The
integrated housing body 1801 may be manufactured out of ABS, PP,
PC, PPE, or any other suitable material capable of withstanding the
pressure and heat generated within the integrated housing body 1801
during operation of the boundary-layer pump.
[0097] During the fill operation of the pumping system, depicted by
FIG. 18, a flapper valve 1815 is opened at the inlet and a gas
(e.g. ambient air) is drawn into a boundary-layer pump. A
simplified depiction of the motor 720 and disks (730, 801, 802) is
provided, which represents a design similar to that of
boundary-layer pump 700 depicted in FIGS. 7A-10, except that the
pressure recovery chamber housing cover 710 and body 711 are
replaced by the integrated housing 1801. The boundary-layer pump
impels the air by the rotation of the disks into the pressure
recovery involute and out of the pump outlet. The pressure recovery
chamber within the integrated housing 1801 is similarly shaped as
the pressure recovery chamber of the boundary-layer pump of FIGS.
7A-10. After the gas travels through the pump outlet, it passes the
open solenoid valve 1813 into the manifold chamber, and from the
manifold chamber it passes through the opened solenoid valve 1810
to one or more chambers of the air mattress. Solenoid valve 1811,
depicted as closed, may also be opened if simultaneous filling of
the chambers connected to valves 1810 and 1811 is desired. During
fill operation, solenoid valve 1812 connecting the manifold chamber
to the dump channel and solenoid valve 1814 connecting the pump
outlet to the exhaust remain closed.
[0098] During the powered dump operation of the pumping system,
depicted by FIG. 19, the flapper valve 1815 at the inlet and the
solenoid valve 1813 between the pump outlet and the manifold
chamber are closed, and the solenoid valve 1814 at the exhaust and
the solenoid valve 1812 at the dump channel are opened. Solenoid
valve 1811, depicted as closed, may also be opened if simultaneous
powered dumping of the chambers connected to valves 1810 and 1811
is desired. Gas is then drawn from the one or more air mattress
chambers connected to solenoid valve 1810 into the manifold, past
open solenoid valve 1812, through the dump channel, and into the
boundary-layer pump. The boundary-layer pump then impels the air
outwards through the pump outlet and past open solenoid valve 1814
into the exhaust channel.
[0099] It will be appreciated that although solenoid valves and a
flapper valve are depicted in FIGS. 18 and 19, other types of
valves may be used. Solenoid valves are preferable at various
connection points as they are a cost-effective way of achieving
positive electromechanical control, while a flapper valve, which
does not provide positive control over the flow, is preferable as a
cost-effective way of implementing a valve where positive control
over the flow is not required (e.g. at the inlet). Furthermore, it
will be appreciated that FIGS. 18 and 19 are merely an exemplary
embodiment illustrating the inventive principles, and the
integrated housing need not be designed exactly as depicted. One
skilled in the art would be able to produce variations of the
physical design of the integrated housing based on the teachings
herein.
[0100] FIG. 20 provides a cross-sectional view of another exemplary
integrated housing 2000, having an integrated housing body 2001,
which utilizes two sets of disks on either side of a motor 720
(along with corresponding pressure recovery chambers, pump outlets,
inlets, and valves). The integrated housing 2000 is capable of
generating a greater amount of flow to one or more air mattress
chambers than the exemplary integrated housing 1800 of FIGS. 18 and
19 by compounding the flow from two sets of disks. The integrated
housing 2000 is also capable of utilizing the two sets of disks to
perform a powered dump of one or more air mattress chambers at a
compounded rate of flow. One skilled in the art will appreciate
that, instead of utilizing one motor with multiple sets of disks,
the integrated housing 2000 can be adjusted to accommodate two
independent pumps with separate motors. However, utilizing a single
boundary layer pump with one motor and sets of disks connected to
either side of the motor is particularly suitable for the
integrated housing 2000, allowing a single boundary layer pump to
efficiently produce a compounded flow that would have required two
independent pumps to produce, while requiring lower cost and
occupying less space than two independent pumps.
[0101] In FIG. 20, the integrated housing 2000 is depicted during
fill operation of one or more chambers of an air mattress connected
to the integrated housing 2000 by open solenoid valve 2010. Gas
flows into the integrated housing 2000 past flapper valves 1815,
2015 at both inlets and is drawn into the sets of disks on both
sides of the motor 720, as indicated by the bolded arrows in FIG.
20. Gas is then impelled through pressure recovery chambers on both
sides of motor 720 by the rotation of the sets of disks, out of
pump outlets on both sides of motor 720, and into the manifold
chamber through open solenoid valves 1813, 2013. In this
illustrative embodiment, only solenoid valve 2010 is open, and thus
only the chamber (or chambers) of the air mattress connected to the
manifold outlet corresponding to solenoid valve 2010 is filled.
However, it will be appreciated that any number of the solenoid
valves 1810, 1811, 2010, 2011 corresponding to manifold outlets may
be opened such that any number of chambers may be simultaneously
filled or dumped.
[0102] To perform a powered dumping operation of one or more
chambers of an air mattress utilizing the integrated housing 2000,
the flapper valves 1815, 2015 at the inlets and solenoid valves
1813, 2013 connecting the pump outlets to the manifold chamber are
closed. Solenoid valves 1812, 2012 connecting the manifold chamber
to dump channels on both sides of the motor 720 and solenoid valves
1814, 2014 connecting the pump outlets to an exhaust channel are
opened. Any number of solenoid valves 1810, 1811, 2010, 2011 may be
opened depending on which corresponding chambers are to be dumped.
Gas will then flow from the one or more chambers through the
manifold chamber, through the dump channels on both sides of the
motor 720, and be drawn into the two sets of disks. The gas is then
impelled by the rotation of the sets of disks out of the pump
outlets on both sides of the motor 720, and out through the exhaust
channel.
[0103] FIG. 21 provides a cross-sectional view of yet another
exemplary integrated housing 2100, similar to the integrated
housing 2000 of FIG. 20, except that the manifold chamber of
integrated housing 2000 is divided into two separate manifold
chambers in integrated housing 2100. Separating the manifold
chamber into two manifold chambers allows each set of disks to
service different manifold outlets separately, making it possible
to perform a fill operation with one set of disks for one or more
chambers while simultaneously performing a dump operation with the
other set of disks for one or more other chambers. FIG. 21 depicts
the left side of integrated housing 2100 performing a powered dump
operation with respect to the one or more chambers connected to the
manifold outlet corresponding to open solenoid valve 1810, while at
the same time performing a fill operation with respect to the one
or more chambers connected to the manifold outlet corresponding to
open solenoid valve 2010. The flow of gas is depicted by the arrows
in FIG. 21, traveling a similar path on the filling side and the
dumping side as described with respect to FIGS. 18 and 19,
respectively.
[0104] It will be appreciated that, as with other embodiments of
the described invention, the solenoid valves are capable of
positive control over the flow in connection with control unit 114,
and therefore, although the motor 720 rotates both sets of disks at
the same amount of RPMs, the amount of gas being pumped into the
manifold chambers on either side of the integrated housing 2100 may
be simultaneously and independently controlled. Thus, the
integrated housing 2100 is further capable of simultaneously
dumping different amounts of gas from both sides of the integrated
housing 2100, filling both sides of the integrated housing 1100 to
different amounts of pressure, or dumping a certain amount from one
side while filling the other side with a different amount. It will
further be appreciated that, as with other embodiments of the
described invention, "one-way" solenoid valves (i.e. solenoid
valves that only make a seal in the relaxed state) are preferable
due to their effectiveness in positive flow control applications
and relatively low cost. It will further be appreciated that, while
the amount of gas allowed into a chamber may be controlled through
the solenoid valves, the flow rate is determined by the RPMs of the
disk arrays, the physical geometry of the disk arrays and the
chambers surrounding the disk arrays, and the back pressure at the
outlets corresponding to the disk arrays.
[0105] In a further embodiment, the separate manifold chambers may
be connected, and the connection may include a valve, such that the
pump is capable of filling or dumping with compounded flow with
respect to any of the manifold outlets (when the valve is open), as
well as being capable of independently and simultaneously filling
and dumping with respect to separate manifold outlets (when the
valve is closed). This is described in further detail below with
respect to FIG. 24.
[0106] FIG. 22 provides a cross-sectional view of yet another
exemplary integrated housing 2200, similar to the integrated
housing 2000 of FIG. 20, and capable of performing compounded flow
(with solenoid valve 2215 closed) as described above with respect
to FIG. 20. The integrated housing 2200 further comprises a
pressure channel that connects a pump outlet corresponding to one
set of disks to a pump inlet corresponding to the other set of
disks. The pressure channel is depicted as passing under the motor
720 in FIG. 22, but it will be appreciated that the design and
position of the pressure channel may be varied or modified, so long
as the pressure channel allows gas to travel from the pump outlet
corresponding to one set of disks into the disk inlets of the other
set of disks.
[0107] When the pressure channel valve 2215 is open and other
valves 1813, 1814 at the first pump outlet are closed, gas that
enters the integrated housing at the inlet corresponding to open
flapper valve 1815 is impelled by rotation of the disks (on the
left side of the motor 720) through the pressure channel and
further impelled by rotation of the disks (on the right side of the
motor 720) into the manifold chamber and out through the manifold
outlets. This design allows for compounding of pressure (as opposed
to the compounding of flow when valve 2215 is closed and the two
sets of disks are operated in parallel), as the rotation of the
first set of disks raises the pressure of the gas within the
pressure channel, and thus gas is entering the second set of disks
at a higher initial pressure than if it had entered the second set
of disks from the atmosphere through the inlet 2015 (e.g. during a
compounded flow operation). The rotation of the second set of disks
allows a relatively higher pressure (up to more than double the
amount of pressure relative to a boundary-layer pump with only one
set of disks) in the manifold chamber and in any air mattress
chamber connected to the manifold chamber by an open valve (e.g.
solenoid valve 2010 as depicted).
[0108] As mentioned above, in alternative implementations, the
chamber surrounding the first set of disks may be designed with an
annular shape rather than an involute shape. It will be appreciated
that, while a pressure recovery involute has many advantages
including packaging and manufacturing simplicity, other types of
expansion plenums may be advantageous for compounding pressure. For
example, if the chamber around the first set of disks has an
annular design, it may be more efficient in pumping an air mattress
chamber on its own or in compounding flow. However, the annular
design, which is particularly suited to deliver pressurized flow to
a desired location in a compounding pressure implementation, may be
more difficult to manufacture and may be more costly as a result.
An example of one implementation of a boundary-layer pump including
multiple annular pressure recovery stage is discussed in further
detail below with reference to FIGS. 30 and 31.
[0109] FIG. 23 provides a cross-sectional view of yet another
exemplary integrated housing 2300, similar to the integrated
housing 2200 of FIG. 22 and also capable of compounding flow and
compounding pressure as described above with respect to FIG. 22.
FIG. 23, however, instead of having a similarly-sized sets of disks
on both sides of the motor, has differently-sized sets of disks on
either side of the motor. This allows greater control for achieving
specific pressure values, as well as increasing the efficiency of
the pump during the compounding flow operation (regardless of
whether the pump is filling or dumping). Given Bernoulli's
principle and the insensitivity to pressure changes, the geometry,
number and spacing of disks in a disk array at a given RPM may be
tailored and matched to provide an optimally efficient design for
generating or compounding pressure, balancing the flow area through
the sets of disks with the expected amount of compression of gas,
as described below. The arrows depicted in FIG. 23 illustrate the
path traveled by gas during filling operation with compounded
pressure.
[0110] Using the iterative calculation method described above based
on Bernoulli's principle, an optimal disk inlet area of the second
set of disks and the corresponding pressure recovery chamber may be
determined by using the p.sub.2 used for the calculation pertaining
to the first set of disks as the p.sub.1 for the calculation
pertaining to the second set of disks. Generally, this will result
in smaller A1 and A2 values with respect to the second set of
disks. However, while A1 and A2 may be smaller, it will be
appreciated the p2/p1 ratio may be affected by disk size, RPMs,
disk inlet design and number of disks, so in certain
implementations, the actual size of the second set of disks need
not be smaller than the first set of the disks, depending on the
RPMs and number of disks used.
[0111] Fine-tuning of the pressure may be achieved in the one or
more air mattress chambers connected to the manifold outlet at
solenoid valve 2010 with an appropriate control algorithm, as a
control routine with a set feedback rate will intrinsically provide
a "finer" level of control with a smaller array of disks (as
depicted to the right of the motor 720 in FIG. 23). A simple
control loop carried out by a micro-controller within the control
unit may include: initiating a pressure measurement, averaging a
number of readings obtained through analog to digital converter
hardware, determining whether the averaged value is below or above
the target, and continuing or stopping the process based on the
determination. The control loop takes time to carry out these steps
(somewhere in the neighborhood of 100 ms to 500 ms), and the
boundary-layer pump may be filling or dumping while the control
loop is taking measurements. Thus, when the measured pressure
approaches the target pressure, it may be advantageous to switch
from using a larger disk array or both disk arrays to only using
the smaller disk array in order to allow for "finer" control.
[0112] In an illustrative example, if the desired pressure is
relatively low, both sets of disks may be used to quickly fill a
chamber to a pressure that is close to the desired pressure through
compounded flow (i.e. with valves 1815, 2015, 1813, 2013 and 2010
open while leaving all other valves closed), and after a certain
point when the pressure in the chamber approaches the desired
pressure, only the second, smaller set of disks is used to achieve
the desired pressure (e.g. by closing valves 1812, 1813, 1814 and
2215, which isolates the first set of disks from the manifold
chamber; or by closing valves 1812, 1813 and 2215 and opening valve
1814 and having the first set of disks simply impel air from the
inlet to the exhaust). Similarly, in another illustrative example,
if the desired pressure is relatively high, both sets of disks may
be used in compounded flow mode until the pressure reaches a
certain point, and then the appropriate valves could be
closed/opened to change the operation of the two sets of disks to
compounded pressure mode until the desired pressure is achieved. It
will further be appreciated that the described principles may be
applied to the powered dumping operation as well. For example, if
the desired pressure of the chamber is relatively low, both sets of
disks may be used to dump with compounded flow down to a certain
pressure that approaches the desired pressure. Then, after that
point, only the smaller set of disks is used to dump the gas down
to the desired pressure. Alternatively, when the dumping operation
approaches the desired pressure, the motor could simply be shut off
and the air mattress chamber may be allowed to passively deflate
down to the desired pressure.
[0113] FIG. 24 provides a cross-sectional view of yet another
exemplary integrated housing 2400, similar to the integrated
housing 2200 of FIG. 22 and also capable of compounding flow and
compounding pressure as described above with respect to FIG. 22.
The integrated housing 2400 further has a manifold chamber divided
into two separate chambers by a solenoid valve 2416. Inclusion of
two separate chambers within the manifold chambers connected by a
valve allows a single pump to provide a large variety of filling
and dumping options to the air mattress chambers connected to the
manifold outlets.
[0114] With respect to fill operations, the pump may perform
filling with respect to any of the manifold outlets or combination
of manifold outlets with compounded flow (with appropriate valves
1815, 2015, 1813, 2013, 2416 open) or with compounded pressure
(with appropriate valves 1815, 2215, 2013, 2416 open). The pump may
also perform filling operations with respect to two or more
manifold outlets independently with valve 2416 closed. Similarly,
the pump may perform dumping with respect to any of the manifold
outlets or combination of manifold outlets with compounded flow or
compounded pressure with appropriate valves open, and the pump may
also perform dumping operations with respect to two or more
manifold outlets independently with valve 2416 closed.
[0115] Additionally, as depicted in FIG. 25, the pump with
integrated housing 2400 may simultaneously perform dumping with
respect to manifold outlets connected to one chamber of the
manifold chamber while performing filling with respect to manifold
outlets connected to the other chamber of the manifold chamber when
solenoid valve 2416 is closed. On the left side of FIG. 25, gas
from one or more air mattress chambers corresponding to the
manifold outlet at solenoid valve 1810 flows through the dump
channel on the left, into the left set of disks, and is impelled
out the exhaust through open solenoid valve 1814. Meanwhile, on the
right side of FIG. 25, gas is impelled by the right set of disks
2030 from the right inlet into a manifold chamber through solenoid
valve 2013, and further into one or more air mattress chambers
corresponding to the manifold outlet at solenoid valve 2010.
[0116] Furthermore, in FIG. 26, the pump with integrated housing
2400 is depicted during a simultaneous dump and fill operation
where gas from one or more chambers corresponding to one manifold
outlet is pumped directly into one or more chambers corresponding
to another manifold outlet. This type of simultaneous dump and fill
from one outlet to another may be particularly useful in certain
medical applications, such as, for example, where paired dump and
fill operations may be used to roll patients in bed. Gas from one
or more air mattress chambers corresponding to the manifold outlet
at solenoid valve 1810 flows through the dump channel on the left
and is impelled through the left set of disks into the pressure
channel through open solenoid valve 2215. The gas is then further
impelled through the right set of disks 2030 into the manifold
chamber through open solenoid valve 2013, and further into one or
more air mattress chambers corresponding to the manifold outlet at
solenoid valve 2010. In effect, this is similar to a compounded
pressure fill operation of the one or more air mattress chambers
corresponding to the manifold outlet at solenoid valve 2010, except
that the gas is drawn from another air mattress chamber through the
left dump channel instead of through the left housing inlet at
flapper valve 1815.
[0117] For clarity of depiction, only one pressure channel is
depicted in FIGS. 24-26. However, it will be appreciated that the
integrated housing 2400 may include another pressure channel
connecting the outlet of the second set of disks (depicted on the
right) to the inlet of the first set of disks (depicted on the
left), such that there are two separate pressure channels and
simultaneous dumping and filling from one manifold outlet to
another manifold outlet may be performed in either direction,
depending on which valves are open and closed.
[0118] In further embodiments, the integrated housing may be
designed with one motor attached to more than two sets of disks, or
the integrated housing may further include a second motor and
additional sets of disks connected to the second motor. While
implementing these designs with more than two sets of disks is
possible given the teachings herein, the air mattress industry
would not typically require pressures greater than approximately
1.0 psi, which is readily achievable with boundary-layer pump
designs utilizing one or two sets of disks. However, in certain
medical applications or other special circumstances, it is
conceivable that pressures higher than what may be readily
attainable by pump designs utilizing one or two sets of disks may
be useful. In such cases, it will be appreciated that the
principles described herein may be extended to boundary-layer pump
designs utilizing more than two sets of disks. For example, a more
powerful motor may be used in connection with more than two disk
arrays with appropriate adjustments to the integrated housing. In
another example, separate integrated housings may be modified to
allow connection to one another to utilize multiple motors and a
plurality of disk arrays.
[0119] It will be appreciated that the integrated housing designs
depicted in FIGS. 22-24 using two sets of disks are well-suited for
a broad performance spectrum, allowing a large range of pressures
and flows to be produced from a single device depending on the
application. Simply by opening and closing the appropriate valves
through the control unit, the pump can fill or dump, one or more
chambers of an air mattress, independently or simultaneously, at a
flow rate within a broad range of flow rates, to pressures within a
broad range of pressures. In certain embodiments, different
chambers may be filled and dumped independently and simultaneously,
and in further embodiments, differently-sized disks further allow
for higher pressure compounding efficiency or fine-tuning of the
filling and dumping operations.
[0120] While the boundary-layer pump is particularly suited for the
exemplary embodiments of integrated housings depicted in FIGS.
18-24 due to its ability to generate relatively large amounts of
flow as well as relatively large amounts of pressure, it will also
be appreciated that the depicted integrated housings can be
modified to accommodate other types of pumps, such as replacing the
boundary layer pump two sets of disk arrays with multiple squirrel
cage blowers or diaphragm pumps, making appropriate modifications
to the housing as necessary. However, due to the efficiency
advantages, cost advantages, and relative simplicity of design of
using a boundary-layer pump, utilizing other types of pumps with
the depicted integrated housings is not preferable.
[0121] It will further be appreciated that, for certain exemplary
pump products, the boundary layer pumps depicted in the various
embodiments of FIGS. 18-24 may be housed separately from the
manifold chambers in a more distributed pump housing rather than
the integrated housing depicted in FIGS. 18-24. In exemplary
embodiments having separate housings for the pump and the manifold
chamber, appropriate connections between the housings are made. For
example, pump outlets may be connected to a separately housed
manifold chamber through appropriate tubes and valves, and the
manifold chamber could include additional ports to connect the
manifold to the pump inlets (the connection being the dump channel
for powered dumping applications). However, having an integrated
housing may often be preferable due to efficiency, cost, and design
advantages relative to a distributed housing.
[0122] It will also further be appreciated that the various
embodiments depicted in FIGS. 18-26 allow manifold-driven powered
dumping using a motor rotating in one direction. Although a
reversible motor could be used in the embodiments depicted in FIGS.
18-26, the dump channel allows the rotation of the set or sets of
disk in just one direction to achieve filling operation and/or
powered dumping based on which valves are open or closed (as
discussed above in detail).
[0123] The configurations of pump housings utilizing
manifold-driven powered dumping are more complex and more expensive
than pump housings utilizing pump-driven powered dumping, requiring
more valves and additional manufacturing considerations. However,
these manifold-driven configurations significantly outperform the
pump-driven configurations in powered dumping trials. Thus, as
mentioned above, there is a tradeoff between performance and
complexity (and cost). The pump housing configurations utilizing
manifold-driven powered dumping have the best performance, but
require greater cost and complexity relative to the pump housing
configurations using
[0124] For comparison, FIGS. 27 and 28 depict an integrated housing
2700 that utilizes pump-driven powered dumping. This exemplary
integrated housing 2700 allow for a smaller pump housing having
fewer components, but also does not achieve as much negative
pressure during powered dumping as pump housing configurations
utilizing manifold-driven powered dumping.
[0125] FIG. 27 is a schematic diagram showing air flow through an
integrated housing 2700 during filling operation. The pump in FIG.
27 may be any of the pumps capable of powered dumping discussed
above with respect to FIGS. 14A-16D (or a pump having another
similar design). During filling operation, the pump inlet is open
(i.e., exposing the pressure recovery chamber to atmosphere via the
pump inlet), as represented in FIG. 27 by an open valve, and air
passes through the pump inlet to the disks and is impelled into the
manifold chamber past open valve 2713 and out of the manifold past
open valve 2710. During filling operation, a sheath or plug
isolates the pressure recovery chamber from the exhaust (as shown
in FIG. 27). During powered dumping operation, as depicted in FIG.
28, the pump inlet would be closed (i.e., not exposing the pressure
recovery chamber to atmosphere via the pump inlet), and the sheath
or plug would be positioned so as to expose the pressure recovery
chamber to the exhaust.
[0126] In a further embodiment designed for an extremely cost
sensitive application, valve 2713 could be omitted from the pump
configuration shown in FIGS. 27-28 at the expense of not having a
redundantly sealed air chamber.
[0127] Based on the disclosures provided herein, it can be seen
that there are a wide variety of pump housing configurations that
can be tailored to fit particular performance and cost
requirements. An example of a relatively low-cost configuration
that is still able to achieve the relatively advanced function of
powered dumping from one air mattress chamber to another air
mattress chamber is presented in FIG. 29.
[0128] FIG. 29 depicts an integrated housing 2900 that utilizes the
relatively low-cost pump-driven powered dumping design utilizing a
non-reversible motor discussed above with respect to FIGS. 16A-16D
together with the double-sided disk array integrated housing
configurations depicted in FIGS. 20-26. The integrated housing 2900
includes a manifold chamber with manifold outlets corresponding to
solenoid valves 2910, 2911, 2920, 2921, and a valve 2916 for
isolating one part of the manifold chamber from another. The arrows
shown in FIG. 29 correspond to air being dumped from one chamber
corresponding to manifold valve 2910 and pumped into another
chamber corresponding to manifold valve 2920 via the rotation of
both sets of disks attached to the motor 720. The pump
corresponding to the disk array on the left side of FIG. 29 has its
pump inlet in a closed position and its pump exhaust connected to
the pressure channel in an open position, while the pump
corresponding to the disk array on the right side of FIG. 29 has
its pump inlet in an open position and its pump exhaust connected
to the pressure channel in a closed position (i.e., blocked by a
plug or sheath). Both sides have the housing inlets in a closed
position and pump exhausts connected to atmosphere in a closed
position.
[0129] It will be appreciated that, with different valves opened
and closed, the integrated housing 2900 allows for a variety of
other filling and powered dumping operations as well, including,
for example, filling one or more chambers with compounded flow,
filling a chamber while simultaneously dumping another chamber
(where the filling is performed with external air and the dumped
air leaves the pump through the an exhaust connected to
atmosphere), and compounded dumping of one or more chambers.
Furthermore, it will be appreciated that the integrated housing
2900 achieves this variety of capabilities while requiring
relatively less solenoid valves and a simpler manifold design than
is required by the integrated housings having double-sided disk
array configurations utilizing a dump channel as shown in FIGS.
20-26 above.
[0130] While the embodiments of boundary-layer pumps referred to
above have generally been discussed in the context of having an
involute shape for the pressure recovery chamber, it will be
appreciated that other designs of the expansion plenum (i.e., the
pressure recovery chamber) may be used depending on the context.
For example, an annular design for the expansion plenum may be
preferable in applications where compounding pressure is
particularly important. In a further embodiment, the inlet and
outlet of an annular expansion plenum are positioned in line with
each other.
[0131] In yet another further embodiment, both annular and
involute-shaped pressure recovery chambers can be used together in
multiple stages, for example, in applications requiring a large
amount of pressure. An example of a three-stage configuration 3000
showing simplified depictions of the disk arrays and the shapes of
the multiple pressure recovery chambers is provided by FIG. 30. Gas
flows into the first annular pressure recovery stage (at the top of
FIG. 30) through a pump inlet, and rotation of the disks in the
first annular pressure recovery stage causes the gas to be impelled
radially outwards to the walls of the first stage. The gas passes
through a second annular pressure recovery stage and finally an
involute-shaped pressure recovery stage, which impels the gas out
through a pump outlet. Because of the shape of the annular pressure
recovery stages shown in FIG. 30, the flow fields within the disk
stacks created by the annular pressure recovery stages are
relatively more uniform and more efficient relative to
involute-shaped pressure recovery stages.
[0132] The three-stage configuration 3000 having two annular
pressure recovery stages and one involute pressure recovery stage
is shown in the context of an integrated housing 3100 in FIG. 31.
The integrated housing 3100 allows the boundary-layer pump having
motor 3120 and a three-stage configuration to achieve filling
operation and powered dumping in a manner that is similar to what
was discussed above with respect to FIGS. 18-19 (with the opening
and closing of appropriate valves). The arrows in FIG. 31 show the
flow of gas through the integrated housing 3100 during a filling
operation. It will be appreciated that a pump product utilizing the
boundary-layer pump with three stages and pump housing depicted in
FIG. 31 will be more complex and more expensive than one that
utilizes the single stage configuration shown in FIGS. 18-19, but
will also be able to achieve significantly higher pressures. It
will further be appreciated that the multi-stage design shown in
FIG. 31 (and other variations of annular, involute-shaped, and
combination single-stage or multi-stage designs) can be used in one
or both sides of the double-sided pump and pump housing designs
shown in FIGS. 20-26.
[0133] Thus, embodiments of the described invention provide quick,
efficient, and cost-effective systems and methods for inflating or
deflating an air mattress by using a boundary-layer pump and
appropriate manifold housing, and the invention is uniquely suited
to applications requiring high flow rates with low to moderate
pressure requirements in homogeneous or non-homogeneous
compressible fluids. It will also be appreciated, however, that the
foregoing methods and implementations are merely examples of the
inventive principles, and that these illustrate only preferred
techniques. A multitude of different designs are possible based on
the principles described herein, including but not limited to:
single disk array configurations, multiple disk array
configurations using a single motor, multiple disk array
configurations using multiple motors, as well as various
configurations based on pump-driven or manifold-driven powered
dumping. Further, because these pump and pump housing
configurations can use reversible or non-reversible motors, more or
less valves, more or less complex housing configurations, and
different types of pressure recovery chambers, there is a wide
gamut of performance and cost requirements that can be satisfied by
employing pump and pump housing configurations according to the
principles described herein.
[0134] It is thus contemplated that other embodiments of the
invention may differ in detail from foregoing examples. As such,
all references to the invention are intended to reference the
particular example of the invention being discussed at that point
in the description and are not intended to imply any limitation as
to the scope of the invention more generally. All language of
distinction and disparagement with respect to certain features is
intended to indicate a lack of preference for those features, but
not to exclude such from the scope of the invention entirely unless
otherwise indicated.
[0135] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0136] Accordingly, this invention includes all modifications and
equivalents of the subject matter recited in the claims appended
hereto as permitted by applicable law. Moreover, any combination of
the above-described elements in all possible variations thereof is
encompassed by the invention unless otherwise indicated herein or
otherwise clearly contradicted by context.
* * * * *
References