U.S. patent application number 14/083476 was filed with the patent office on 2015-05-21 for electric vehicle undercarriage crumple zone.
This patent application is currently assigned to ATIEVA, INC.. The applicant listed for this patent is ATIEVA, INC.. Invention is credited to Peter Dore Rawlinson.
Application Number | 20150135939 14/083476 |
Document ID | / |
Family ID | 53171967 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150135939 |
Kind Code |
A1 |
Rawlinson; Peter Dore |
May 21, 2015 |
Electric Vehicle Undercarriage Crumple Zone
Abstract
A battery pack protection system is provided for use with an
electric vehicle in which the battery pack is mounted under the
car. The system utilizes a plurality of deformable cooling conduits
located between the lower surface of the batteries within the
battery pack and the lower battery pack enclosure panel. The
cooling conduits are configured to deform and absorb impact energy
when an object, such as road debris, strikes the lower surface of
the lower battery pack enclosure panel. Further protection may be
achieved by positioning a ballistic shield, alone or with a layer
of compressible material, under the bottom surface of the battery
pack.
Inventors: |
Rawlinson; Peter Dore;
(Worcestershire, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ATIEVA, INC. |
Redwood City |
CA |
US |
|
|
Assignee: |
ATIEVA, INC.
Redwood City
CA
|
Family ID: |
53171967 |
Appl. No.: |
14/083476 |
Filed: |
November 19, 2013 |
Current U.S.
Class: |
89/36.08 ;
429/72 |
Current CPC
Class: |
H01M 10/613 20150401;
F41H 5/013 20130101; B60R 16/04 20130101; H01M 2/1083 20130101;
B60K 2001/005 20130101; B60Y 2306/01 20130101; F41H 7/042 20130101;
B60K 1/04 20130101; B60Y 2306/05 20130101; Y02E 60/10 20130101;
H01M 10/625 20150401; B60K 2001/0438 20130101; H01M 10/6568
20150401; H01M 2/1077 20130101; F41H 5/04 20130101 |
Class at
Publication: |
89/36.08 ;
429/72 |
International
Class: |
F41H 7/04 20060101
F41H007/04; F41H 5/013 20060101 F41H005/013; F41H 5/04 20060101
F41H005/04; H01M 10/625 20060101 H01M010/625 |
Claims
1. A battery pack protection system, comprising: a battery pack
mounted under an electric vehicle, wherein said battery pack is
configured to house a plurality of batteries; and a plurality of
deformable cooling conduits interposed between a lower surface of
each of said plurality of batteries and an upper surface of a lower
battery pack enclosure panel, wherein integral to each of said
plurality of deformable cooling conduits is at least one coolant
channel, and wherein said plurality of deformable cooling conduits
are configured to deform and absorb impact energy when an object
strikes a lower surface of said lower battery pack enclosure
panel.
2. The battery pack protection system of claim 1, wherein said
plurality of deformable cooling conduits are positioned within said
battery pack such that coolant within said at least one coolant
channel of said plurality of deformable cooling conduits flows
within a plane that is substantially parallel to said upper surface
of said lower battery pack enclosure panel.
3. The battery pack protection system of claim 1, wherein each of
said plurality of batteries utilizes a cylindrical form factor.
4. The battery pack protection system of claim 3, wherein said
plurality of batteries are positioned within said battery pack such
that a cylindrical axis corresponding to each of said plurality of
batteries is substantially perpendicular to said lower battery pack
enclosure panel, and wherein said plurality of deformable cooling
conduits are interposed between a base surface of each of said
plurality of batteries and said upper surface of said lower battery
pack enclosure panel.
5. The battery pack protection system of claim 4, wherein said
plurality of deformable cooling conduits are positioned within said
battery pack such that coolant within said at least one coolant
channel of each of said plurality of deformable cooling conduits
flows within a plane that is substantially perpendicular to said
cylindrical axis corresponding to each of said plurality of
batteries.
6. The battery pack protection system of claim 1, wherein each of
said plurality of deformable cooling conduits includes a plurality
of coolant channels, and wherein each of said plurality of coolant
channels has a circular cross-section.
7. The battery pack protection system of claim 1, wherein each of
said plurality of deformable cooling conduits includes a plurality
of coolant channels, and wherein each of said plurality of coolant
channels has a non-circular cross-section.
8. The battery pack protection system of claim 1, wherein each of
said plurality of deformable cooling conduits is comprised of a
plastic polymer material.
9. The battery pack protection system of claim 8, wherein said
plastic polymer material is selected from the group consisting of
polyethylene and polypropylene.
10. The battery pack protection system of claim 1, wherein said
lower battery pack enclosure panel is comprised of a metal.
11. The battery pack protection system of claim 10, wherein said
metal is selected from the group consisting of aluminum and
steel.
12. The battery pack protection system of claim 1, further
comprising a ballistic shield mounted under said electric vehicle
and below said battery pack, wherein said ballistic shield is
interposed between said battery pack and a road surface.
13. The battery pack protection system of claim 12, wherein said
ballistic shield is spaced apart from said lower battery pack
enclosure panel by a distance within the range of 1 centimeter to
15 centimeters.
14. The battery pack protection system of claim 12, wherein said
ballistic shield is fabricated from a metal.
15. The battery pack protection system of claim 12, wherein said
ballistic shield is fabricated from a high density plastic.
16. The battery pack protection system of claim 12, further
comprising a layer of a compressible material interposed between
said ballistic shield and said battery pack.
17. The battery pack protection system of claim 12, wherein said
compressible material is selected from the group of materials
consisting of open-cell sponge, open-cell foam, closed-cell sponge
and closed-cell foam.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to electric vehicles
and, more particularly, to a system for providing undercarriage
protection to an electric vehicle.
BACKGROUND OF THE INVENTION
[0002] In response to the demands of consumers who are driven both
by ever-escalating fuel prices and the dire consequences of global
warming, the automobile industry is slowly starting to embrace the
need for ultra-low emission, high efficiency cars. While some
within the industry are attempting to achieve these goals by
engineering more efficient internal combustion engines, others are
incorporating hybrid or all-electric drive trains into their
vehicle line-ups. To meet consumer expectations, however, the
automobile industry must not only achieve a greener drive train,
but must do so while maintaining reasonable levels of performance,
range, reliability, and cost.
[0003] In recent years there have been several incidents of a
battery pack, either contained within a laptop computer or utilized
in a vehicle, catching on fire. As a result, one of the primary
issues impacting consumer confidence with respect to both hybrid
and all-electric vehicles is the risk of a battery pack fire.
[0004] Rechargeable batteries, due to their chemistries, tend to be
relatively unstable and more prone to thermal runaway than
non-rechargeable batteries. Thermal runaway occurs when the
battery's internal reaction rate increases to such an extent that
it is generating more heat than can be withdrawn. If reaction rate
and heat generation go unabated, eventually the heat generated
becomes great enough to cause the battery and materials in
proximity to the battery to combust. Typically thermal runaway is
the result of a battery short, damage due to improper use or
physical abuse, a manufacturing defect, or exposing the cell to
extreme temperatures.
[0005] Hybrid and electric vehicle (EV) manufacturers use a variety
of techniques to shield their battery packs from possible damage
that may result from road debris or a vehicle collision. For
example, in a vehicle using a relatively small battery pack such as
a hybrid, the pack may be protected by placing it within the rear
trunk, behind the rear seats, under the front seats, or in another
comparatively well protected location. Vehicles utilizing large
battery packs typically are forced to mount the pack under the car.
To protect such a pack, a ballistic shield may be located between
the road surface and the bottom of the pack, as disclosed in U.S.
Pat. No. 8,286,743, issued 16 Oct. 2012, and U.S. Pat. No.
8,393,427, issued 12 Mar. 2013.
[0006] Although the prior art teaches a variety of mounting
techniques that can either be used to place the battery pack in a
relatively protected region of a car or to otherwise shield the
battery pack from potential harm, given the severity of the
consequences accompanying a catastrophic battery pack event,
further techniques for protecting an under-carriage mounted battery
pack are desired. The present invention provides such a protection
scheme.
SUMMARY OF THE INVENTION
[0007] The present invention provides a battery pack protection
system for use with an electric vehicle in which the battery pack
is mounted under the car. The system utilizes a plurality of
deformable cooling conduits located between the lower surface of
the batteries within the battery pack and the lower battery pack
enclosure panel. The cooling conduits are configured to deform and
absorb impact energy when an object, such as road debris, strikes
the lower surface of the lower battery pack enclosure panel. The
deformable cooling conduits include one or more coolant channels
that may utilize either a circular or non-circular cross-section.
The coolant flowing within the coolant channels flows within a
plane that is substantially parallel to the lower battery pack
enclosure panel. The deformable cooling conduits may be fabricated
from a plastic polymer material (e.g., polyethylene, polypropylene,
etc.) and the lower battery pack enclosure panel may be fabricated
from a metal (e.g., aluminum, steel, etc.).
[0008] In one aspect, cylindrical batteries are used, for example
batteries utilizing an 18650 form factor, and positioned within the
pack such that the cylindrical axis of each of the batteries is
substantially perpendicular to the lower battery pack enclosure
panel. The cooling conduits are interposed between the base surface
of each of the batteries and the lower battery pack enclosure
panel, preferably such that the coolant within the coolant channels
of the cooling conduits flows within a plane that is substantially
perpendicular to the cylindrical axes of the batteries.
[0009] In another aspect, a ballistic shield is mounted under the
electric vehicle and under the battery pack, thus providing
additional battery pack protection. The ballistic shield, which is
typically fabricated from either a metal or a high density plastic,
is mounted at some distance (e.g., between 1 and 15 centimeters)
from the bottom of the battery pack enclosure. A layer of a
compressible material such as an open- or closed-cell foam or an
open- or closed-cell sponge may be interposed between the battery
pack and the ballistic shield.
[0010] 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
[0011] FIG. 1 provides a perspective view of a battery pack and the
vehicle chassis to which it is to be mounted;
[0012] FIG. 2 provides a cross-sectional view of a portion of the
battery pack shown in FIG. 1;
[0013] FIG. 3 illustrates an exemplary cooling system suitable for
use with the battery pack deformable cooling conduits of the
invention;
[0014] FIG. 4 illustrates an alternate exemplary cooling system
suitable for use with the battery pack deformable cooling conduits
of the invention;
[0015] FIG. 5 illustrates the exemplary cooling system shown in
FIG. 3 with a different coolant conduit configuration within the
battery pack;
[0016] FIG. 6 provides the cross-sectional view of the battery pack
portion shown in FIG. 2 after an object strikes the bottom of the
battery pack enclosure;
[0017] FIG. 7 provides the cross-sectional view of the battery pack
portion shown in FIG. 2 with an alternate configuration for the
deformable cooling conduits;
[0018] FIG. 8 provides the cross-sectional view of the battery pack
portion shown in FIG. 2 with an alternate configuration for the
deformable cooling conduits;
[0019] FIG. 9 provides the cross-sectional view of the battery pack
portion shown in FIG. 2 with an alternate configuration for the
deformable cooling conduits;
[0020] FIG. 10 provides the cross-sectional view of the battery
pack portion shown in FIG. 9 with the addition of an underlying
ballistic shield; and
[0021] FIG. 11 provides the cross-sectional view of the battery
pack portion shown in FIG. 10 with the addition of a compressible
layer interposed between the battery pack lower panel and the
ballistic shield.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0022] 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 battery configurations and chemistries.
Typical battery chemistries include, but are not limited to,
lithium ion, lithium ion polymer, nickel metal hydride, nickel
cadmium, nickel hydrogen, nickel zinc, and silver zinc. The terms
"battery pack" and "battery pack enclosure" may be used
interchangeably and refer to an enclosure containing one or more
batteries electrically interconnected to achieve the desired
voltage and capacity. The term "electric vehicle" as used herein
may refer to an all-electric vehicle, also referred to as an EV, a
plug-in hybrid vehicle, also referred to as a PHEV, or a hybrid
vehicle, also referred to as a HEV, where a hybrid vehicle utilizes
multiple sources of propulsion including an electric drive
system.
[0023] FIG. 1 provides a perspective view of a battery pack 101
configured to be mounted under vehicle chassis 103. It should be
understood that the present invention is not limited to a specific
battery pack mounting scheme, battery pack size, or battery pack
configuration.
[0024] FIG. 2 provides a cross-sectional view of a portion of
battery pack 101. For purposes of clarity, battery interconnects
and battery mounts are not included in this view. Visible in FIG. 2
is a portion of the upper pack enclosure panel 201, a portion of
the lower pack enclosure panel 203, and a plurality of batteries
205. Note that the enclosure side panels are not shown in this
view. Batteries 205 are preferably cylindrical batteries, for
example batteries utilizing an 18650 form-factor, and are
positioned within the battery pack so that the axis of the cylinder
(i.e., the cylindrical axis) is substantially perpendicular to both
lower enclosure panel 203 and the surface of the road. Interposed
between the base of each cylindrical battery 205 and lower panel
203 are a plurality of deformable cooling conduits 207 through
which a liquid coolant, i.e., a heat transfer medium, is pumped. As
shown, in the preferred embodiment cooling conduits 207 are aligned
with lower panel 203, resulting in the coolant within channels 209
flowing in a direction substantially perpendicular to the axes of
the cylindrical batteries. By regulating the flow of coolant within
conduits 207 and/or regulating the transfer of heat from the
coolant to another temperature control system, the temperature of
cells 205 may be regulated so that the cells remain within their
preferred operating range.
[0025] FIGS. 3 and 4 illustrate exemplary cooling systems that may
be coupled to cooling conduits 207. In system 300 shown in FIG. 3,
the coolant within conduits 207 is pumped through a radiator 301
using a pump 303. A blower fan 305 may be used to force air through
radiator 301 to insure cooling when the car is stationary. In
system 400 shown in FIG. 4, the coolant within conduits 207 is
coupled to a thermal management system 401 via a heat exchanger
403. Preferably thermal management system 401 is a refrigeration
system and as such, includes a compressor 405 to compress the low
temperature vapor in refrigerant line 407 into a high temperature
vapor and a condenser 409 in which a portion of the captured heat
is dissipated. After passing through condenser 409, the refrigerant
changes phases from vapor to liquid, the liquid remaining at a
temperature below the saturation temperature at the prevailing
pressure. The refrigerant then passes through a dryer 411 that
removes moisture from the condensed refrigerant. After dryer 411,
refrigerant line 407 is coupled to heat exchanger 403 via thermal
expansion valve 413 which controls the flow rate of refrigerant
into heat exchanger 403. Additionally, in the illustrated system a
blower fan 415 is used in conjunction with condenser 409 to improve
system efficiency. It should be understood that battery pack
coolant conduits 207 may be coupled to other cooling/thermal
management systems, and the cooling systems shown in FIGS. 3 and 4
are only meant to illustrate some common configurations for use
with the conduits of the invention. Additionally, the geometry of
cooling conduits 207 shown in FIGS. 3 and 4 is only meant to
illustrate one possible configuration. For example, FIG. 5 shows
the cooling system of FIG. 3 with a different conduit configuration
within battery pack 101, one utilizing coolant manifolds. The
invention may use other configurations as well, assuming that the
conduits are placed between the batteries 205 and the lower
enclosure panel 203 as previously described and illustrated.
[0026] Cooling conduits 207 serve a two-fold purpose. First, during
normal operation of the vehicle and the battery pack, the coolant
within conduits 207 draws heat away from batteries 205, thereby
allowing the temperature of the batteries to remain within the
preferred operating range. Second, during a non-normal event in
which an object such as road debris from under the vehicle strikes
the bottom panel 203 of pack 101, conduits 207 help to prevent
catastrophic damage to the pack by absorbing energy through conduit
deformation. As illustrated in FIG. 6, when an object under the
vehicle is forced upwards in direction 601, the object causes the
bottom enclosure panel 203 to deform as well as those portions of
conduits 207 within the strike zone. As the lower panel 203 and the
conduits within the strike region deform, energy is absorbed. If
sufficient energy is absorbed through this process, damage to the
batteries 205 within the strike region can be significantly
limited, thereby potentially averting a thermal runaway event.
Preferably conduits 207 are fabricated from polyethylene or a
similar material which is capable of severe deformation without
cracking or breaking. Additionally, by selecting an electrically
non-conductive coolant, if conduits 207 do crack or break when
deformed, the released coolant will not cause a short within the
battery pack.
[0027] It will be appreciated that the amount of protection
provided by the battery pack's cooling conduits can be easily
tailored to meet the design requirements for a particular vehicle.
For example and as shown in FIG. 7, by increasing the depth of the
conduits, and thus the separation distance between lower enclosure
panel 203 and batteries 205, a larger deformation zone is provided.
A larger deformation zone, in turn, allows an object striking the
bottom of the battery pack to deform both panel 203 and conduits
701 to a much greater extent before the batteries are damaged.
Additionally, due to the larger internal diameter of channels 703
within conduits 701, a greater degree of conduit deformation may
occur before coolant flow within the affected conduit stops
completely. An added benefit of this approach is that the larger
channels within conduits 701 provide greater cooling capacity.
[0028] FIG. 8 illustrates another embodiment of the invention in
which the number of channels 801 within each conduit 803 is
increased and the shape of each channel has been changed to
cylindrical. As a result, the compression strength of the conduits
has been increased, leading to a less deformable structure. At the
same time, given the size of the channels as well as the number of
channels in proximity to each battery 205, during a deformation
event (i.e., a collision with an object) it is less likely that all
cooling will be terminated for any particular cell.
[0029] FIG. 9 illustrates another embodiment of the invention. In
this embodiment both the corners of each conduit 901 and the
corners of each channel 903 within the conduits are rounded. As a
result, the large conduit surface area in contact with the battery
structures is retained while still achieving a conduit which is
less likely to break during deformation.
[0030] As previously noted, the undercarriage crumple zone of the
present invention can be tailored to meet the specific requirements
for a particular vehicle design. Therefore a vehicle in which the
battery pack is very exposed, for example due to a low mounting
location under the vehicle, or in which the battery pack is more
likely to encounter more road debris, for example in a sport
utility vehicle (SUV), can be provided with more protection than a
vehicle in which the battery pack is less exposed or less likely to
encounter road debris. Features of the crumple zone that can be
altered to achieve the desired characteristics include the number
of channels per conduit, width and height of the conduits,
cross-sectional shape and size of each channel, cross-sectional
shape and size of each conduit, conduit wall thickness (i.e., the
thickness of the wall separating the channels from the outer
conduit wall), conduit material, lower enclosure panel thickness,
and lower enclosure panel material. Preferably the deformable
cooling conduits are made from a plastic polymer such as
polyethylene or polypropylene. If desired, the material may be
treated to improve thermal conductivity, while still retaining its
electrically non-conductive properties. The lower enclosure panel
is preferably fabricated from a metal such as aluminum or steel,
although other materials may be used (e.g., a composite
material).
[0031] In at least one embodiment, and as illustrated in FIG. 10,
the performance of the undercarriage crumple zone is enhanced
through the inclusion of a ballistic shield 1001 mounted between
the lower battery pack enclosure panel 203 and the road surface
(not shown). Shield 1001 absorbs some of the impact energy from
road debris or other objects prior to those objects striking the
outer surface of panel 203. Furthermore, by spacing shield 1001 at
some distance from panel 203 as shown in the preferred embodiment,
shield 1001 is less likely to be driven into the lower enclosure
panel during a strike. Accordingly, while shield 1001 may be
mounted to, and in contact with, panel 203, preferably it is spaced
between 1 and 15 centimeters apart from panel 203. Shield 1001 may
be fabricated from a metal (e.g., aluminum), although preferably a
lighter weight material such as a high density plastic is used in
order to lower vehicle weight.
[0032] FIG. 11 illustrates a modification of the embodiment shown
in FIG. 10. In the illustrated embodiment, a layer of a
compressible material 1101 is interposed between shield 1001 and
lower enclosure panel 203 to aid in impact energy absorption.
Preferably layer 1101 is fabricated from an open- or closed-cell
sponge or foam, for example fabricated from silicone or urethane,
although other similar low density materials may be used for layer
1101. It will be appreciated that the embodiments shown in FIGS. 10
and 11, while based on the embodiment shown in FIG. 9, can utilize
any of the conduit/channel configurations described above.
[0033] It should be understood that the accompanying figures are
only meant to illustrate, not limit, the scope of the invention and
should not be considered to be to scale.
[0034] 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.
* * * * *