U.S. patent application number 13/308300 was filed with the patent office on 2012-06-28 for system for absorbing and distributing side impact energy utilizing an integrated battery pack.
This patent application is currently assigned to TESLA MOTORS, INC.. Invention is credited to Alan Paul Clarke, Hitendra Laxmidas Gadhiya, Peter Dore Rawlinson.
Application Number | 20120161472 13/308300 |
Document ID | / |
Family ID | 45509189 |
Filed Date | 2012-06-28 |
United States Patent
Application |
20120161472 |
Kind Code |
A1 |
Rawlinson; Peter Dore ; et
al. |
June 28, 2012 |
System for Absorbing and Distributing Side Impact Energy Utilizing
an Integrated Battery Pack
Abstract
An energy absorbing and distributing side impact system for use
with a vehicle is provided, the system utilizing a battery pack
enclosure that includes a plurality of cross-members that
transverse the battery pack enclosure and absorb and distribute at
least a portion of the load received when either the first or
second side of the vehicle receives a side impact. The battery pack
enclosure is positioned between the front and rear vehicle
suspension assemblies and mounted between, and mechanically coupled
to, vehicle structural members (e.g., rocker panels) located on
either side of the vehicle. In addition to providing rigidity,
strength and impact resistance, the battery pack cross-members
segregate the batteries contained within the battery pack enclosure
into battery groups.
Inventors: |
Rawlinson; Peter Dore;
(Playa Del Rey, CA) ; Clarke; Alan Paul; (Redondo
Beach, CA) ; Gadhiya; Hitendra Laxmidas; (Irvine,
CA) |
Assignee: |
TESLA MOTORS, INC.
Palo Alto
CA
|
Family ID: |
45509189 |
Appl. No.: |
13/308300 |
Filed: |
November 30, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61426254 |
Dec 22, 2010 |
|
|
|
Current U.S.
Class: |
296/187.08 |
Current CPC
Class: |
B60R 16/04 20130101;
Y02T 10/70 20130101; B60L 50/66 20190201; B62D 25/2036 20130101;
B62D 25/025 20130101; B60K 1/04 20130101; B62D 25/20 20130101; B62D
21/157 20130101; B60K 2001/0438 20130101 |
Class at
Publication: |
296/187.08 |
International
Class: |
B62D 25/20 20060101
B62D025/20 |
Claims
1. An energy absorbing and distributing side impact system for a
vehicle, comprising a battery pack enclosure configured to hold a
plurality of batteries, said battery pack enclosure mounted between
a first vehicle structural side member located adjacent to a first
side of said vehicle and a second vehicle structural side member
located adjacent to a second side of said vehicle, said battery
pack enclosure mounted between a front vehicle suspension assembly
and a rear vehicle suspension assembly, wherein said battery pack
enclosure transverses the distance between said first vehicle
structural side member and said second vehicle structural side
member, wherein a first side member of said battery pack enclosure
is mechanically coupled to said first vehicle structural side
member and a second side member of said battery pack enclosure is
mechanically coupled to said second vehicle structural side member,
wherein said battery pack enclosure further comprises a plurality
of cross-members integrated into said battery pack enclosure,
wherein each of said plurality of cross-members transverses the
distance between said first and second side members of said battery
pack enclosure, wherein said plurality of cross-members segregate
said plurality of batteries into groups of batteries, wherein each
of said plurality of cross-members extends from said first side
member of said battery pack enclosure to said second side member of
said battery pack enclosure, and wherein a side impact load
received on either said first side or said second side of said
vehicle is transferred to at least some of said plurality of
cross-members.
2. The energy absorbing and distributing side impact system of
claim 1, wherein said battery pack enclosure is mounted below a
vehicle floor panel.
3. The energy absorbing and distributing side impact system of
claim 1, wherein said first vehicle structural side member is a
left side rocker panel, and wherein said second vehicle structural
side member is a right side rocker panel.
4. The energy absorbing and distributing side impact system of
claim 1, said first side member of said battery pack enclosure
further comprising an extended region mechanically coupled to a
first vehicle structural side member lower surface, and said second
side member of said battery pack enclosure further comprising an
extended region mechanically coupled to a second vehicle structural
side member lower surface.
5. The energy absorbing and distributing side impact system of
claim 4, wherein said extended region of said first side member of
said battery pack enclosure is bolted using a first plurality of
bolts to said first vehicle structural side member lower surface,
and wherein said extended region of said second side member of said
battery pack enclosure is bolted using a second plurality of bolts
to said second vehicle structural side member lower surface.
6. The energy absorbing and distributing side impact system of
claim 1, wherein said battery pack enclosure is substantially
airtight.
7. The energy absorbing and distributing side impact system of
claim 1, wherein each of said plurality of cross-members includes
at least one cavity extending an entire length of said
corresponding cross-member.
8. The energy absorbing and distributing side impact system of
claim 7, wherein each of said plurality of cross-members is
fabricated from an extruded aluminum.
9. The energy absorbing and distributing side impact system of
claim 7, wherein each of said plurality of cross-members is
fabricated from an extruded aluminum alloy.
10. The energy absorbing and distributing side impact system of
claim 7, wherein each cavity of said at least one cavity
corresponding to each cross-member of said plurality of
cross-members is filled with a high melting temperature, low
thermal conductivity material.
11. The energy absorbing and distributing side impact system of
claim 7, wherein a liquid is contained within each cavity of said
at least one cavity corresponding to each cross-member of said
plurality of cross-members.
12. The energy absorbing and distributing side impact system of
claim 1, wherein each of said plurality of cross-members is
comprised of an upper member and a lower member.
13. The energy absorbing and distributing side impact system of
claim 12, wherein said upper member of each of said plurality of
cross-members includes at least one cavity extending an entire
upper member length, and wherein said lower member of each of said
plurality of cross-members includes at least one cavity extending
an entire lower member length.
14. The energy absorbing and distributing side impact system of
claim 12, wherein said upper member of each of said plurality of
cross-members is mechanically coupled to a battery pack enclosure
top panel, and wherein said lower member of each of said plurality
of cross-members is mechanically coupled to a battery pack
enclosure bottom panel.
15. The energy absorbing and distributing side impact system of
claim 1, wherein each of said plurality of cross-members is
fabricated from a material selected from the group of materials
consisting of aluminum, aluminum alloys and steel.
16. The energy absorbing and distributing side impact system of
claim 1, wherein said battery pack enclosure further comprises a
battery pack bottom panel and a battery pack top panel, wherein
said first and second side members of said battery pack enclosure,
said battery pack bottom panel and said battery pack top panels are
each fabricated from a material selected from the group of
materials consisting of aluminum, aluminum alloys and steel.
17. The energy absorbing and distributing side impact system of
claim 16, wherein said battery pack bottom panel is welded, brazed,
soldered or bonded to said first and second side members of said
battery pack enclosure.
18. The energy absorbing and distributing side impact system of
claim 16, wherein said battery pack top panel is bolted to said
first and second side members of said battery pack enclosure.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims benefit of the filing date of
U.S. Provisional Patent Application Ser. No. 61/426,254, filed Dec.
22, 2010, the disclosure of which is incorporated herein by
reference for any and all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates generally to vehicle
structures and, more particularly, to means for enhancing the side
impact performance of a vehicle.
BACKGROUND OF THE INVENTION
[0003] Modern vehicles use a variety of structures to protect the
vehicle's occupants during a crash. Some of these structures are
used to control the transmission of the crash energy to the
passenger compartment while other structures, such as seat belts,
head restraints, and air bags, are intended to restrain passenger
movement during a crash, thereby preventing the passengers from
hurting themselves as their bodies react to the crash forces. Side
impact collisions present a particularly challenging problem to
vehicle safety engineers, both due to the relatively low position
of the rocker panels on many small vehicles as well as the
difficulty of implementing an impact resistant side structure while
taking into account vehicle doors and doorways.
[0004] U.S. Pat. No. 6,676,200, issued 13 Jan. 2004, discloses an
automotive structure utilizing inner and outer rocker panels, a
floor pan joined to the inner rocker panels, and a plurality of
cross-members that extend laterally across a portion of the vehicle
body. The cross-members include energy absorbing extensions
designed to absorb side impact loads.
[0005] An alternate approach to achieving impact resistance is
disclosed in U.S. Pat. No. 6,793,274, issued 21 Sep. 2004, in which
an energy management system is integrated within various automotive
structural components, e.g., vehicle frames and rails. In
particular, the disclosed system uses members or inserts that are
in some way attached to selected structural components of the
vehicle, the members designed to both absorb and redirect the
impact energy encountered during a crash. The disclosed members
also help to reinforce the components to which they are attached.
The patent describes a variety of ways in which the disclosed
members may be incorporated into a vehicle during the manufacturing
process.
[0006] U.S. Pat. No. 7,090,293, issued 15 Aug. 2006, attempts to
achieve improved occupant protection through a seat assembly that
is designed to provide side impact rigidity and resistance to
rocker override and side impact intrusions. The disclosed seat
assembly includes a frame track, a frame base slidably engaged to
the frame track, a frame back rotatably engaged to the frame base,
and a rear lateral support assembly that includes a support frame
attached to the rear portion of the frame base. The support frame
includes a tubular member that is designed to engage with a vehicle
rocker panel during impact, thereby providing additional rigidity
and strength to the vehicle.
[0007] U.S. Pat. No. 8,007,032, issued 30 Aug. 2011, discloses an
automotive energy absorbing side structure that includes a
wide-based B-pillar with an internal reinforcing tube, a rocker
with an internal bulkhead, a rear rocker, and at least one
cross-member extending inward from the rocker. The disclosed
cross-members are designed to transfer impact loads to the floor,
the cross-members and the tunnel brace.
[0008] Although vehicle manufacturers use a variety of structures
and components to protect a vehicle's occupants during a side
impact collision, typically these approaches provide only limited
protection while significantly increasing vehicle weight.
Accordingly, what is needed is a system that provides superior
vehicle occupant safety, particularly from side impact collisions,
while adding minimal weight from impact resistant dedicated
structures. The present invention provides such a system.
SUMMARY OF THE INVENTION
[0009] The present invention provides an energy absorbing and
distributing side impact system for use with a vehicle, the system
utilizing a battery pack enclosure that includes a plurality of
cross-members that transverse the battery pack enclosure and absorb
and distribute at least a portion of the load received when either
the first or second side of the vehicle receives a side impact. In
accordance with the invention, the battery pack enclosure is
positioned between the front and rear vehicle suspension assemblies
and mounted between, and mechanically coupled to, vehicle
structural members (e.g., rocker panels) located on either side of
the vehicle. The battery pack side members may include extended
regions that simplify mechanically coupling the battery pack
enclosure to the vehicle structural members. In addition to
providing rigidity, strength and impact resistance, the battery
pack cross-members segregate the batteries contained within the
battery pack enclosure into battery groups. The battery pack
cross-members may also be used to thermally segregate battery
groups from one another. Preferably the battery pack enclosure is
mounted below the vehicle floor panel.
[0010] The cross-members integrated into the battery pack enclosure
of the invention may include one or more cavities that extend the
entire cross-member length, where the cavities may be unfilled or
configured to contain a high melting temperature, low thermal
conductivity material or configured to contain a liquid; the
cross-members may be fabricated from aluminum (e.g., extruded
aluminum), an aluminum alloy (e.g., extruded aluminum alloy),
steel, or other material; the cross-members may be comprised of an
upper member and a lower member; the cross-members may be comprised
of an upper member that includes at least one cavity that extends
the entire cross-member length and a lower member that includes at
least one cavity that extends the entire cross-member length; and
the cross-members may be comprised of an upper member that is
mechanically coupled to the battery pack enclosure top panel and a
lower member that is mechanically coupled to the battery pack
enclosure bottom panel.
[0011] The battery pack enclosure may be configured as a
substantially airtight enclosure. The battery pack enclosure,
including side members, top panel and bottom panel, may be
fabricated from aluminum, an aluminum alloy, steel, or other
material. The battery pack bottom panel may be welded, brazed,
soldered or bonded to the enclosure side members. The battery pack
top panel may be bolted to the enclosure side members.
[0012] A further understanding of the nature and advantages of the
present invention may be realized by reference to the remaining
portions of the specification and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 provides a simplified bottom view of an electric
vehicle with a battery pack incorporated into the vehicle
structure;
[0014] FIG. 2 provides a perspective view of a vehicle's
undercarriage with the battery pack incorporated into the vehicle
structure;
[0015] FIG. 3 provides a perspective view of a portion of a vehicle
body and frame with the battery pack separated from the
structure;
[0016] FIG. 4 provides a perspective view of the battery pack shown
in FIGS. 1-3;
[0017] FIG. 5 provides a perspective view of the battery pack shown
in FIGS. 1-4, with the top panel removed;
[0018] FIG. 6 provides a perspective view of the battery pack shown
in FIGS. 1-5, this view showing three of the battery modules in
place within the pack;
[0019] FIG. 7 provides a perspective, cross-sectional view of the
battery pack shown in FIGS. 1-6 mounted under the floor panel of
the vehicle shown in FIG. 3;
[0020] FIG. 8 provides a detailed cross-sectional view of one of
the cross-members shown in FIG. 7;
[0021] FIG. 9 provides a detailed cross-sectional view of an
alternate cross-member;
[0022] FIG. 10 provides a detailed cross-sectional view of an
alternate cross-member;
[0023] FIG. 11 provides a detailed cross-sectional view of an
alternate cross-member;
[0024] FIG. 12 provides a perspective view of the battery pack to
rocker panel assembly; and
[0025] FIG. 13 provides a cross-sectional view of the assembly
shown in FIG. 12.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0026] In the following text, the terms "battery", "cell", and
"battery cell" may be used interchangeably and may refer to any of
a variety of different cell types, chemistries and configurations
including, but not limited to, lithium ion (e.g., lithium iron
phosphate, lithium cobalt oxide, other lithium metal oxides, etc.),
lithium ion polymer, nickel metal hydride, nickel cadmium, nickel
hydrogen, nickel zinc, silver zinc, or other battery
type/configuration. The term "battery pack" as used herein refers
to multiple individual batteries contained within a single piece or
multi-piece housing, the individual batteries electrically
interconnected to achieve the desired voltage and capacity for a
particular application. The term "electric vehicle" as used herein
refers to either an all-electric vehicle, also referred to as an
EV, plug-in hybrid vehicles, also referred to as a PHEV, or a
hybrid vehicle (HEV), a hybrid vehicle utilizing multiple
propulsion sources one of which is an electric drive system.
[0027] The present invention integrates a battery pack into an
electric vehicle in order to add rigidity to the vehicle structure
and significantly increase the vehicle's side impact resistance by
absorbing and distributing the impact load throughout the battery
pack structure. To achieve the desired level of structural
rigidity, strength and impact resistance, preferably the battery
pack is large relative to the overall dimensions of the vehicle and
includes multiple cross-members as described in detail below. In a
preferred embodiment of the invention illustrated in FIGS. 1-3,
battery pack 101 not only transverses the width of the vehicle,
i.e., from rocker panel to rocker panel, but also extends most of
the distance between the front suspension 103 and the rear
suspension 105. It will be appreciated that while smaller battery
packs may be used with the invention, they may not provide the same
level of side impact protection, depending upon their size and the
number of integrated cross-members. In the illustrated embodiment,
battery pack 101 is approximately 2.7 meters long and 1.5 meters
wide. The thickness of battery pack 101 varies from approximately
0.1 meters to 0.18 meters, the thicker dimension applicable to
those portions of the battery pack in which battery modules are
positioned one on top of another, as described further below.
[0028] FIG. 4 provides a perspective view of battery pack 101 with
the top enclosure panel 401 in place, panel 401 preferably
providing a substantially airtight seal. Hollow side structural
elements 403 are also visible, members 403 preferably including an
extended region or lip 405 that is used to mechanically and
thermally couple the side members 403 to the vehicle structure (not
shown in this figure). FIG. 5 shows battery pack 101 with top
member 401 removed, this view showing cross-members 501A-501H. The
number of cross-members is based on the number of cells/cell
modules that are to be encased within the battery pack as well as
the desired structural characteristics of the battery pack.
Preferably battery pack side members 403, including extended region
405, battery pack top panel 401 and battery pack bottom panel 505
are each fabricated from a light weight metal, such as aluminum or
an aluminum alloy, although other materials such as steel may be
used for some or all of the battery pack components. Bottom panel
505 may be welded, brazed, soldered, bonded or otherwise attached
to side members 403, with the resultant joint between panel 505 and
member 403 preferably being substantially air-tight as well as
being strong enough to allow bottom panel 505 to support the
batteries contained within the pack. Top panel 401 is typically
attached to member 403 using bolts or similar means, thus
simplifying battery replacement as well as allowing battery
interconnects, battery pack components, cooling system components
and other battery pack components to be repaired and/or
replaced.
[0029] Cross-members 501A-501H provide several benefits. First and
foremost relative to side impact resistance, members 501A-501H
provide mechanical and structural strength and rigidity to the
battery pack and to the vehicle to which the battery pack is
attached. Additionally, cross-members 501A-501H help to segregate
thermal events by providing a thermal barrier between groups of
cells as well as minimizing gas flow between sections 503, sections
503 being defined by the cross-members, side members 403, top
member 401 and bottom member 505. By segregating thermal events
within smaller groups of cells, thermal runaway propagation is
limited as is the potential for battery pack damage.
[0030] FIG. 6 shows a similar view to that provided by FIG. 5, with
the inclusion of a couple of cell modules 601. In this
illustration, a single module 601 is shown positioned within one of
the seven, larger sections 503 of battery pack 101. Note that each
large section 503 is designed to house a pair of battery pack
modules 601. Additionally, in this illustration there are two
modules 601 stacked one on top of the other in the front section
507 of pack 101. Note that in the preferred embodiment, each module
601 contains 370 individual cells, each cell utilizing an 18650
form factor. It should be understood, however, that this
configuration is only exemplary of a preferred embodiment and that
the invention is equally applicable to other configurations, for
example utilizing batteries with a different form factor, a larger
or smaller number of cells, individual cells versus modules,
etc.
[0031] FIG. 7 provides a perspective, cross-sectional view of
battery pack 101 mounted under floor panel 701 of vehicle 100. This
view also provides additional views of the cross-members. As shown
by the cross-sectional view, in the preferred embodiment
cross-members 501A-501H do not utilize the same cross-section;
rather the cross-section of each is optimized for each member's
location within the pack. In general, cross-members 501A-501H may
either be comprised of a single unit or, as preferred and
illustrated, comprised of an upper member and a lower member. One
or both members may be hollow, thus achieving the desired rigidity
and strength while minimizing weight. It should be understood that
not only can the configuration/design of the cross-members vary,
depending upon their location within the pack, so can the materials
comprising the cross-members. Therefore while cross-members
501A-501H are preferably fabricated from aluminum or an aluminum
alloy, for example using an extrusion process, other materials
(e.g., steel, ceramics, etc.) may also be used if such materials
fit both the mechanical and thermal goals for the particular
cross-member in question. Additionally, the lumens within one or
more of the cross-members may be unfilled or filled with a high
melting temperature, low thermal conductivity material (e.g.,
fiberglass or similar materials). Alternately, the lumens within
the cross-members may include a liquid (e.g., water), the liquid
being either stagnant or flowing. If stagnant, the liquid may be
contained within the lumens themselves or, as preferred, contained
within pouches that fit within the cavities. If the liquid is
flowing, it is preferably contained within tubing that is inserted
within the cross-member cavities and either coupled to a battery
cooling system or used in a stand-alone circulation system.
[0032] In the preferred embodiment, and as illustrated in FIG. 7,
cross-members 501D and 501E are larger than the other central
cross-members. The reason for the increased size is to provide
additional cross-member strength at those locations that are most
critical to achieving the desired level of side-impact resistance.
As shown in the detailed cross-sectional view of FIG. 8, in the
preferred embodiment cross-members 501D and 501E are comprised of
an upper member 801 that is attached to battery pack top panel 401
and includes a single lumen 803, and a lower member 805 that is
attached to battery pack bottom panel 505 and includes a pair of
lumens 807 and 809. In this embodiment, member 801 is approximately
19 millimeters high, 30 millimeters wide, and has a wall thickness
of between approximately 2 and 3 millimeters. Member 805 is
approximately 54 millimeters high, 26 millimeters wide, and has a
wall thickness of between approximately 2 and 3 millimeters.
[0033] Cross-members 501B, 501C, 501F and 510G are slightly smaller
than cross-members 501D and 501E, although they retain the basic
shape of the larger cross-members. As shown in the detailed
cross-sectional view of FIG. 9, these cross-members are comprised
of an upper member 901 that is attached to battery pack top panel
401 and includes a single lumen 903, and a lower member 905 that is
attached to battery pack bottom panel 505 and includes a pair of
lumens 907 and 909. In this embodiment, member 901 is approximately
19 millimeters high, 16 millimeters wide, and has a wall thickness
of between approximately 2 and 3 millimeters. Member 905 is
approximately 54 millimeters high, 16 millimeters wide, and has a
wall thickness of between approximately 2 and 3 millimeters. Note
that the spacing between upper member 801 and lower member 805, and
the spacing between upper member 901 and lower member 905, is used
in the preferred embodiment to capture a battery module mounting
bracket (not shown in FIGS. 8 and 9).
[0034] Cross-member 501A, located near the rear of battery pack 101
and illustrated in the detailed cross-section of FIG. 10, includes
a first member 1001 that extends from battery pack lower panel 505
to battery pack top panel 401. Member 1001 is comprised of a large
lower section 1003 and a small upper section 1005 with respective
lumens 1007 and 1009. Section 1003 of member 1001 is approximately
54 millimeters high, 30 millimeters wide, and has a wall thickness
of between approximately 2 and 4 millimeters. Section 1005 of
member 1001 is approximately 29 millimeters high, 13 millimeters
wide, and has a wall thickness of between approximately 2 and 3
millimeters. Cross-member 501A also includes a second member 1011
that includes a single lumen 1013 as shown. Member 1011 is
approximately 29 millimeters high, 16 millimeters wide, and has a
wall thickness of between approximately 2 and 3 millimeters.
[0035] Cross-member 501H shown in the detailed view of FIG. 11, is
located near the front of battery pack 101 and between battery pack
section 507 and the adjacent section 503. As section 507 is
designed to house two battery pack modules, one on top of the
other, this portion of battery pack 101 utilizes a different design
which, in turn, affects the design of cross-member 501H. As shown,
cross-member 501H includes an upper member 1101 that has a single
lumen 1103, and a lower member 1105 that has a single lumen 1107.
Member 1101 is approximately 54 millimeters high, 26 millimeters
wide, and has a wall thickness of between approximately 2 and 3
millimeters. Member 1105 is approximately 29 millimeters high, 26
millimeters wide, and has a wall thickness of between approximately
2 and 3 millimeters.
[0036] FIGS. 12 and 13 provide perspective and cross-sectional
views, respectively, that illustrate the attachment of the battery
pack 101 to vehicle structural side member 1201. In the preferred
embodiment structural side member 1201 is comprised of a rocker
panel, also referred to herein as a sill, which is formed from
extruded aluminum or an aluminum alloy (although other materials
such as steel may be used for members 1201). Preferably a seal or
gasket is located between the top surface 1301 of side members 403
and the bottom surface 1303 of the top panel 401, thus achieving a
substantially air-tight seal. An o-ring groove 1304 is visible in
FIG. 13 for use with such a seal. In the illustrated embodiment,
each side member 403 includes four lumens 1305-1308. Lower exterior
lumen 1308 is positioned under the extended region 405 of side
member 403. Lumen 1308 is perforated on upper surface 1309 and
lower surface 1311, the perforations on these two surfaces being
aligned such that bolts 1313, or similar means, may pass completely
through lumen 1308, thereby allowing bolts 1313 to couple extended
region 405 of member 403 to structural side member 1201 as shown.
Bolts 1313 and channel nuts 1315 securely attach side members 403,
and therefore battery pack 101, to the vehicle's structural members
1201. Preferably channel nuts 1315 are held in place during
assembly using channel nut retainer 1317. In addition to providing
a strong mechanical coupling, this approach allows battery pack 101
to be quickly and efficiently removed from underneath vehicle
101.
[0037] It should be understood that identical element symbols used
on multiple figures refer to the same component, or components of
equal functionality. Additionally, the accompanying figures are
only meant to illustrate, not limit, the scope of the invention and
should not be considered to be to scale.
[0038] Systems and methods have been described in general terms as
an aid to understanding details of the invention. In some
instances, well-known structures, materials, and/or operations have
not been specifically shown or described in detail to avoid
obscuring aspects of the invention. In other instances, specific
details have been given in order to provide a thorough
understanding of the invention. One skilled in the relevant art
will recognize that the invention may be embodied in other specific
forms, for example to adapt to a particular system or apparatus or
situation or material or component, without departing from the
spirit or essential characteristics thereof. Therefore the
disclosures and descriptions herein are intended to be
illustrative, but not limiting, of the scope of the invention which
is set forth in the following claims.
* * * * *