Battery Pack Optimization for Thermal Management
A battery pack for an electric vehicle or a hybrid vehicle may include a housing, a stack of battery cells disposed within the housing, and a cooling subassembly. The housing typically holds the cell stack together, and the cooling subassembly typically cools the cell stack to prevent damage to the battery cells and to maintain the performance of the battery cells. The cooling subassembly may include a cold plate defining a liquid flow channel and one or more thermoelectric devices (TEDs) that are operable to cool the cell stack when current is supplied thereto. Heat spreaders may be employed within the battery pack, and exemplary configurations of components to thermally and mechanically couple the cooling subassembly are described.
This application claims the benefit under 35 U.S.C.§ 119(e) of U.S. Provisional Patent Application No. 62/547,549 filed Aug. 18, 2017, which is incorporated by reference herein.
FIELDThe present disclosure relates to battery pack optimization for thermal management.
BACKGROUNDThe background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A battery pack in an electric vehicle or a hybrid vehicle typically includes a housing, a stack of lithium ion battery cells disposed within the housing, and a cooling subassembly disposed below the cell stack. The housing holds the cell stack together, and the cooling subassembly cools the cell stack to prevent damage to the battery cells and to maintain the performance of the battery cells. The cooling subassembly typically includes a cold plate defining a liquid flow channel, and a plurality of thermoelectric devices (TEDs) that are operable to cool the cell stack when current is supplied thereto.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
In the drawings, reference numbers may be reused to identify similar and/or identical elements.
DETAILED DESCRIPTIONReferring now to
The first sidewall 46 has an inner surface 52, an outer surface 54, and a window or opening 55 that extends through the inner and outer surfaces 52 and 54. The opening 55 is located closer to the open end 40 of the housing 32 than the end wall 50 of the housing 32. For example, the opening 55 is longitudinally spaced apart from the end wall 50 by a first distance D1, and the opening 55 is longitudinally spaced apart from the open end 40 by a second distance D2 that is less than the first distance. In addition, as shown in
The first sidewall 46 includes a pair of hollow cylindrical bosses 58 disposed on opposite sides of the opening 55 and a pair of mounting feet 60 disposed on opposite sides of the opening 55. The bosses 58 and the mounting feet 60 form part of the outer surface 54 of the first sidewall 46. The ones of the bosses 58 and the mounting feet 60 located adjacent to the open end 40 receive fasteners (e.g., screws) 61 that attach the cover 38 to the first sidewall 46. The ones of the bosses 58 and the mounting feet 60 located adjacent to the end wall 50 can receive fasteners (not shown) that attach the end wall 50 to the first sidewall 46. Alternatively, the end wall 50 can be integrally formed with the remainder of the housing 32. Each of the mounting feet 60 defines a groove 62 for mounting the battery pack 30 in a vehicle.
With brief additional reference to
Referring now to
Each of the battery cells 78 includes a pair of terminals or tabs 84. The tabs 84 are disposed adjacent to the open end 40 of the housing 32. In this regard, the cover 38 may include a power management module and/or a thermal management module. The power management module is electrically connected to the tabs 84 of the battery cells 78 and controls the amount of power flowing to and from the battery cells 78. Thus, the tabs 84 may be disposed adjacent to the open end 40 to reduce the amount of wiring required for this electrical connection. The thermal management module controls the temperature of the battery cells 78 as discussed in more detail below.
In a conventional battery pack, the cooling subassembly is located at the bottom of the battery pack, and the tabs of the battery cells are located at the top of the battery pack. Thus, the cooling subassembly is located on the opposite side of the battery pack than the tabs of the battery cells, where most of the heat is generated in the battery pack. In addition, since the cooling subassembly is located at the bottom of the battery pack, the battery cells cannot be stacked as high as they may otherwise be if the cooling subassembly was not located at the bottom of the battery pack.
In contrast, as discussed above, the cooling subassembly 36 is mounted on the first sidewall 46 of the housing 32, and the tabs 84 of the battery cells 78 are disposed adjacent to the open end 40 of the housing 32 that adjoins the first sidewall 46. Thus, the cooling subassembly 36 is located closer to the tabs 84 of the battery cells 78 relative to conventional battery packs, which improves the thermal management of the battery pack 30. In addition, since the cooling subassembly 36 is located on the side of the housing 32 rather than the bottom of the housing 32, the battery cells 78 can be stacked higher in the housing 32 relative to conventional battery packs. Therefore, for a given battery pack packaging space, the battery pack 30 can include more battery cells than conventional battery packs.
Each of the heat spreaders 82 includes a flat body 86 and a head 88. The flat body 86 has a first longitudinal side 90, a second longitudinal side 92 opposite of the first longitudinal side 90, a first major surface 94 extending between the first and second longitudinal sides 90 and 92, and a second major surface 96 opposite of the first major surface 94. The head 88 is attached to the first longitudinal side 90 of the flat body 86.
The head 88 and the flat body 86 collectively have a T-shaped profile as best shown in
Each of the heat spreaders 82 includes a first chamfer 106 and a second chamfer 108. The first chamfer 106 extends between and connects the first portion 98 of the head 88 and the first major surface 94 of the flat body 86. The second chamfer 108 extends between and connects the second portion 102 of the head 88 and the second major surface 96 of the flat body 86. The first and second chamfers 106 and 108 increase the amount of heat absorbing mass of the heat spreaders 82 and place the heat spreaders 82 in closer proximity to seals 109 of the battery cells 78. Thus, the first and second chamfers 106 and 108 may increase the amount of heat absorbed by the heat spreaders 82.
Since the first and second chamfers 106 improve the heat absorption performance of the heat spreaders 82, the first and second portions 98 and 102 of the head 88 may be shorter than otherwise possible. In other words, the first portion 98 of the head 88 may project from the first major surface 94 of the flat body 86 in the first direction 100 to a lesser extent, and the second portion 102 of the head 88 may project from the second major surface 96 of the flat body 86 in the second direction 104 to a lesser extent. Shortening the first and second portions 98 and 102 of the head 88 reduces the surface area of the head 88, which degrades the ability of the heat spreaders 82 to absorb heat. Thus, the first and second chamfers 106 offset this degradation in heat absorption ability, and therefore enable enables the width W of the head 88 to be less than two times the thickness T1 of each of the battery cells 78 as described above.
In addition, shortening the first and second portions 98 and 102 of the head 88 provides clearance for bosses 110 that define blind holes 136, which receive fasteners (e.g., screws) 132 that attach the cooling subassembly 36 to the housing 30. Shortening the first and second portions 98 and 102 of the head 88 also provides clearance for electrical connectors and wiring within the battery pack 30. As a result, the overall packaging space required for the battery pack 30 may be reduced.
As best shown in
Referring now to
As best shown in
The fluid flow path 137 and the cover plate 130 are longitudinally aligned with the opening 26 in the first sidewall 46 of the housing 32. Thus, the fluid flow path 137 is disposed closer to the open end 40 of the housing 40 than to the end wall 50. Therefore, cooling provided by fluid flowing through the fluid flow path 137 is biased toward the tabs 84 of the battery cells 78, which is the location where most of the heat is generated in the battery pack 30.
As best shown in
As best shown in
In a conventional battery pack, the channels for mounting the battery pack are entirely defined by the housing and extend along the entire length of the housing on both longitudinal sides of the housing. However, if the first sidewall 46 of the housing 32 defined a mounting foot with a groove or channel that extends along the entire length of the housing 32, a height H (
Referring again to
As best shown in
The heat distribution plate 122 distributes heat from the cell stack 34 to the TEDs 120. The heat distribution plate 122 can be stamped, cased, or extruded from a metal such as aluminum or steel. The gap pad 124 is disposed between and contacts the heat distribution plate 122 and the heads 88 of the heat spreaders 82. The gap pad 124 enables heat transfer from the cell stack 34 to the cooling subassembly 36 via conduction while providing pliability or compliance to enable assembly of the battery pack 30 despite dimensional tolerances of the components of the battery pack 30. The gap pad 124 can be made from compression foam. The heat distribution plate 122 and the circuit board 118 can be attached to the cold plate 112 using fasteners (e.g., screws) 152 that extend through holes 154 in the heat distribution plate 122, through holes 156 in the circuit board 118, and into blind holes 158 in the cold plate 112.
Referring now to
If a vehicle containing the battery pack 30 is impacted, the battery pack 30 may experience a load due to the impact. The protrusions 162, 164 on the cold plate 160 absorb a portion of the load on the battery pack 30 due to the impact that would otherwise be entirely absorbed by the fasteners 132 attaching the cooling subassembly 36 to the housing 32. Thus, the protrusions 162, 164 improve the structural integrity of the battery pack 30, especially in situations where the battery pack 30 experience a vertical load that would shear the fasteners 132 but for the protrusions 162, 164.
Referring now to
Referring now to
In contrast to the flat body 86 of each of the heat spreaders 82, the second longitudinal side 178 of the flat body 174 of the heat spreader 172 includes an inset portion 184 that is inset relative to the remainder of the second longitudinal side 178. The inset portion 184 of the heat spreader 172 provides additional clearance between the heat spreader 172 and the second sidewall 48 of the housing 32, which may reduce the amount of heat that the heat spreader 172 absorbs from the housing 32. The inset portion 184 may be formed with the remainder of the heat spreader 172 in a single operation (e.g., extrusion), or the inset portion 184 may be formed in a secondary operation (e.g., die cut) after the remainder of the heat spreader 172 is formed.
Referring now to
In contrast to the heat spreaders 82, the heat spreader 186 includes a cylindrical body 200 attached to the second longitudinal side 194 of the flat body 188. The cylindrical body 200 may provide a line contact between the heat spreader 186 and the second sidewall 48 of the housing 32 if there is no gap between the heat spreader 186 and the second sidewall 48. Thus, the portion of the second longitudinal side 194 of the heat spreader 186 in contact with the second sidewall 48 may be less than the portion of each of the heat spreaders 82 in contact with the second sidewall 48. Therefore, the heat spreader 186 may absorb less heat from the second sidewall 48 than each of the heat spreaders 82 when the heat spreaders 82, 186 are sized to contact the second sidewall 48. In addition, the cylindrical body 200 may be hollow as shown in
Since the cylindrical body 200 may enable the heat spreader 186 to contact the second sidewall 48 without absorbing as much heat as the heat spreaders 82, the cylindrical body 200 may enable sizing the heat spreader 186 to contact the second sidewall 48. As a result, the heat spreader 186 may add to the strength of the housing 32 to withstand vehicle impacts that impart a load on the battery pack 30. In addition, due to its round shape, the cylindrical body 200 may prevent the second sidewall 48 from catching on the heat spreader 186 when the battery pack 30 is assembled. Further, the cylindrical body 200 may help to balance a die if an extrusion process is used to make the heat spreader 186.
Referring now to
Similar to the second sidewall 48, the second sidewall 202 may be extruded form a metal such as aluminum. However, a thickness T2 of the second sidewall 202 may be limited due to the extrusion process. Thus, by forming the second sidewall 202 and the plate 212 as separate components, the second sidewall 202 and the plate 212 may have a greater combined thickness and strength than would otherwise be possible with the second sidewall 202 alone. In addition, the plate 212 may be formed (e.g., forged, cast) from a metal (e.g., steel) that is stronger than aluminum, which may further add to the strength of the second sidewall 202.
Referring now to
Similar to the second sidewall 48, the second sidewall 214 may be extruded from a metal such as aluminum. Thus, as discussed above, by forming the second sidewall 214 and the plate 224 as separate components, the second sidewall 214 and the plate 224 may have a greater combined thickness and strength than would otherwise be possible with the second sidewall 214 alone. In addition, the plate 212 may be formed (e.g., forged, cast) from a metal (e.g., steel) that is stronger than aluminum, which may further add to the strength of the second sidewall 214.
The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.
Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information but information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.
In this application, including the definitions below, the term “module” or the term “controller” may be replaced with the term “circuit.” The term “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.
The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules that are connected via interface circuits. For example, multiple modules may allow load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish some functionality on behalf of a client module.
The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple modules. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple modules. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more modules.
The term memory circuit is a subset of the term computer-readable medium.
The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).
The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.
The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc.
The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or JSON (JavaScript Object Notation) (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C #, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCamI, Javascript®, HTML5 (Hypertext Markup Language 5th revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®.
None of the elements recited in the claims are intended to be a means-plus-function element within the meaning of 35 U.S.C. § 112(f) unless an element is expressly recited using the phrase “means for,” or in the case of a method claim using the phrases “operation for” or “step for.”
Claims
1. A battery pack for a vehicle, the battery pack comprising:
- a housing having a bottom wall, a top wall, a first sidewall, a second sidewall disposed opposite of the first sidewall, an end wall, and an open end opposite of the end wall and adjoining the bottom wall, the top wall, the first sidewall, and the second sidewall, the first sidewall having an inner surface, an outer surface, and an opening that extends through the inner and outer surfaces;
- a plurality of battery cells disposed within the housing, each the plurality of battery cells including cell tabs disposed adjacent to the open end of the housing;
- a cover disposed over the open end of the housing; and
- a cooling subassembly disposed over the opening in the first sidewall of the housing, the cooling subassembly including a cold plate and a plurality of thermoelectric devices.
2. The battery pack of claim 1 wherein the open end of the housing is disposed within a first plane, and the opening in the first sidewall of the housing is disposed within a second plane that intersects the first plane.
3. The battery pack of claim 1 wherein the opening in the first sidewall of the housing is located closer to the open end of the housing than the end wall of the housing.
4. The battery pack of claim 1 wherein the outer surface of the first sidewall of the housing defines a first groove for mounting the battery pack in the vehicle.
5. The battery pack of claim 4 wherein the cold plate of the cooling subassembly defines a second groove that is aligned with the first groove, the first and second grooves defining a channel for mounting the battery pack in the vehicle.
6. The battery pack of claim 4 wherein the cold plate of the cooling subassembly includes at least one protrusion projecting into the opening in the first sidewall of the housing and engaging an inner peripheral edge of the opening.
7. The battery pack of claim 1 wherein the second sidewall of the housing has an inner surface, an outer surface, and a plurality of fins projecting from the outer surface of the housing, the outer surface of the housing and adjacent ones of the plurality of fins cooperating to define insulating pockets, the battery pack further comprising a plate disposed over the fins and enclosing the insulating pockets.
8. The battery pack of claim 1 wherein the second sidewall of the housing has an inner surface, an outer surface, and a pair of flanges projecting from the outer surface and defining a channel, the battery pack further comprising a plate that is retained within the channel.
9. A heat spreader for distributing heat way from battery cells in a battery pack of a vehicle, the heat spreader comprising:
- a flat body having a first longitudinal side, a second longitudinal side opposite of the first longitudinal side, a first major surface extending between the first and second longitudinal sides, and a second major surface opposite of the first major surface;
- a head attached to the first longitudinal side of the flat body, the head and the flat body collectively having a T-shaped profile, a first portion of the head projecting from the first major surface of the flat body in a first direction, a second portion of the head projecting from the second major surface of the flat body in a second direction opposite of the first direction;
- a first chamfer extending between and connecting the first portion of the head and the first major surface of the flat body; and
- a second chamfer extending between and connecting the second portion of the head and the second major surface of the flat body.
10. The heat spreader of claim 9 wherein the second longitudinal side of the flat body includes an inset portion that is inset relative to the remainder of the second longitudinal side to provide a clearance between the heat spreader and a housing of the battery pack.
11. The heat spreader of claim 9 further comprising a cylindrical body attached to the second longitudinal side of the flat body.
12. The heat spreader of claim 11, wherein the cylindrical body is hollow.
13. A battery pack for a vehicle, the battery pack comprising:
- a housing,
- a plurality of battery cells disposed within the housing; and
- the heat spreader of claim 9 disposed between adjacent ones of the plurality of battery cells, wherein a width of the head is less than or equal to a product of 1.5 and a thickness of one of the plurality of battery cells.
14. The battery pack of claim 13 wherein the width of the head is less than or equal to the thickness of one of the plurality of battery cells.
15. A housing for a battery pack of a vehicle, the housing comprising:
- a bottom wall;
- a top wall;
- a first sidewall having an inner surface, an outer surface, and an opening that extends through the inner and outer surfaces;
- a second sidewall disposed opposite of the first sidewall; and
- an end wall, the housing having an open end opposite of the end wall and adjoining the bottom wall, the top wall, the first sidewall, and the second sidewall, wherein the opening in the first sidewall is located closer to the open end of the housing than the end wall of the housing.
16. The housing of claim 15 wherein the outer surface of the first sidewall of the housing defines a first groove for mounting the battery pack in the vehicle.
17. The housing of claim 16 wherein the first groove includes a first portion disposed on a first side of the opening in the first sidewall and a second portion disposed on a second side of the opening in the first sidewall opposite of the first side.
18. A battery pack for a vehicle, the battery pack comprising:
- the housing of claim 15;
- a plurality of battery cells disposed within the housing and including cell tabs disposed adjacent to the open end of the housing; and
- a cooling subassembly covering the opening in the first sidewall of the housing, the cooling subassembly including a cold plate and a plurality of thermoelectric devices.
19. The battery pack of claim 18 wherein the cold plate of the cooling subassembly defines a second groove that is aligned with the first groove, the first and second grooves defining a channel for mounting the battery pack in the vehicle.
20. The battery pack of claim 18 wherein the cold plate defines a fluid flow path having an inlet and an outlet, the battery pack further comprising an inlet fitting in fluid communication with the inlet of the fluid flow path, and an outlet fitting in fluid communication with the outlet of the fluid flow path, the inlet and outlet fittings being disposed within a rectangular outer profile defined by the bottom wall of the housing, the top wall of the housing, the first sidewall of the housing, and the second sidewall of the housing.
Type: Application
Filed: Aug 17, 2018
Publication Date: Jul 16, 2020
Inventors: David Scott Thomas (Royal Oak, MI), Alex Ho Yang (Ann Arbor, MI), Timothy Hughes (South Lyon, MI)
Application Number: 16/640,052