The present disclosure relates to hybrid or electric vehicles and batteries for the hybrid or electric vehicles.
Hybrid or electric vehicles may be propelled by an electric machine that draws power from a battery.
A battery for an electric vehicle includes a plurality of cells and a plurality of thermal barriers. The plurality of cells is configured to store electrical energy and discharge the electrical energy to propel the vehicle. Each of thermal barriers is each disposed between adjacent cells of the plurality of cells. Each thermal barrier includes a first thermal insulator, a second thermal insulator, and an endothermic and intumescent layer. The first thermal insulator engages a first of the cells. The second thermal insulator engages a second of the cells. The endothermic and intumescent layer is disposed between the first and second thermal insulators. The endothermic and intumescent layer is configured to, in response to an increase in temperatures of the first and second of the cells and heat generated by the first and second of the cells consuming the first and second thermal insulators, expand, engage the first and second of the cells, and absorb the heat generated by the first and second of the cells.
A battery includes a cell and a thermal barrier. The cell is configured to store and discharge electrical energy. The thermal barrier is disposed along an exterior surface of the cell. The the thermal barrier includes a thermal insulator. The thermal barrier also includes an endothermic and intumescent material. The thermal insulator engages the exterior surface of the cell. The endothermic and intumescent material is disposed on an exterior of the thermal insulator such that the thermal insulator is disposed between the cell and the endothermic and intumescent material. The endothermic and intumescent material is configured to, in response to an increase in a temperature of the cell and heat generated by the cell consuming the thermal insulator, (i) expand, (ii) engage the exterior surface of the cell, and (iii) absorb the heat generated by the cell.
A battery includes a cell and a thermal barrier. The cell is configured to store and discharge electrical energy. The thermal barrier is disposed along an exterior surface of the cell. The thermal barrier includes a thermal insulator. The thermal barrier also includes an endothermic and intumescent material. The thermal insulator engages the exterior surface of the cell. The endothermic and intumescent material is disposed on an exterior of the thermal insulator such that the thermal insulator is disposed between the cell and the endothermic and intumescent material. The endothermic and intumescent material is configured to, in response to an increase in a temperature of the cell and heat generated by the cell not consuming the thermal insulator, (i) expand, (ii) compress and displace the thermal insulator, and (iii) absorb heat generated by the cell.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Referring to
The M/G 14 is a drive source for the electric vehicle 10 that is configured to propel the electric vehicle 10. The M/G 14 may be implemented by any one of a plurality of types of electric machines. For example, M/G 14 may be a permanent magnet synchronous motor. Power electronics 24 condition direct current (DC) power provided by the battery 22 to the requirements of the M/G 14, as will be described below. For example, the power electronics 24 may provide three phase alternating current (AC) to the M/G 14.
If the transmission 16 is a multiple step-ratio automatic transmission, the transmission 16 may include gear sets (not shown) that are selectively placed in different gear ratios by selective engagement of friction elements such as clutches and brakes (not shown) to establish the desired multiple discrete or step drive ratios. The friction elements are controllable through a shift schedule that connects and disconnects certain elements of the gear sets to control the ratio between the transmission output shaft 20 and the transmission input shaft 18. The transmission 16 is automatically shifted from one ratio to another based on various vehicle and ambient operating conditions by an associated controller, such as a powertrain control unit (PCU). Power and torque from the M/G 14 may be delivered to and received by transmission 16. The transmission 16 then provides powertrain output power and torque to output shaft 20.
It should be understood that the hydraulically controlled transmission 16, which may be coupled with a torque converter (not shown), is but one example of a gearbox or transmission arrangement; any multiple ratio gearbox that accepts input torque(s) from a power source (e.g., M/G 14) and then provides torque to an output shaft (e.g., output shaft 20) at the different ratios is acceptable for use with embodiments of the present disclosure. For example, the transmission 16 may be implemented by an automated mechanical (or manual) transmission (AMT) that includes one or more servo motors to translate/rotate shift forks along a shift rail to select a desired gear ratio. As generally understood by those of ordinary skill in the art, an AMT may be used in applications with higher torque requirements, for example.
As shown in the representative embodiment of
The powertrain 12 further includes an associated controller 32 such as a powertrain control unit (PCU). While illustrated as one controller, the controller 32 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that the powertrain control unit 32 and one or more other controllers can collectively be referred to as a “controller” that controls various actuators in response to signals from various sensors to control functions such as operating the M/G 14 to provide wheel torque or charge the battery 22, select or schedule transmission shifts, etc. Controller 32 may include a microprocessor or central processing unit (CPU) in communication with various types of computer readable storage devices or media. Computer readable storage devices or media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM is a persistent or non-volatile memory that may be used to store various operating variables while the CPU is powered down. Computer-readable storage devices or media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller in controlling the engine or vehicle.
The controller 32 communicates with various vehicle sensors and actuators via an input/output (I/O) interface (including input and output channels) that may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing, and/or conversion, short-circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process particular signals before being supplied to the CPU. As generally illustrated in the representative embodiment of
Control logic or functions performed by controller 32 may be represented by flow charts or similar diagrams in one or more figures. These figures provide representative control strategies and/or logic that may be implemented using one or more processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various steps or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Although not always explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending upon the particular processing strategy being used. Similarly, the order of processing is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic may be implemented primarily in software executed by a microprocessor-based vehicle and/or powertrain controller, such as controller 32. Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers depending upon the particular application. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media having stored data representing code or instructions executed by a computer to control the vehicle or its subsystems. The computer-readable storage devices or media may include one or more of a number of known physical devices which utilize electric, magnetic, and/or optical storage to keep executable instructions and associated calibration information, operating variables, and the like.
An accelerator pedal 34 is used by the driver of the vehicle to provide a demanded torque, power, or drive command to the powertrain 12 (or more specifically M/G 14) to propel the vehicle. In general, depressing and releasing the accelerator pedal 34 generates an accelerator pedal position signal that may be interpreted by the controller 32 as a demand for increased power or decreased power, respectively. A brake pedal 36 is also used by the driver of the vehicle to provide a demanded braking torque to slow the vehicle. In general, depressing and releasing the brake pedal 36 generates a brake pedal position signal that may be interpreted by the controller 32 as a demand to decrease the vehicle speed. Based upon inputs from the accelerator pedal 34 and brake pedal 36, the controller 32 commands the torque and/or power to the M/G 14, and friction brakes 38. The controller 32 also controls the timing of gear shifts within the transmission 16.
The M/G 14 may act as a motor and provide a driving force for the powertrain 12. To drive the vehicle with the M/G 14 the traction battery 22 transmits stored electrical energy through wiring 40 to the power electronics 24 that may include inverter and rectifier circuitry, for example. The inverter circuitry of the power electronics 24 may convert DC voltage from the battery 22 into AC voltage to be used by the M/G 14. The rectifier circuitry of the power electronics 24 may convert AC voltage from the M/G 14 into DC voltage to be stored with the battery 22. The controller 32 commands the power electronics 24 to convert voltage from the battery 22 to an AC voltage provided to the M/G 14 to provide positive or negative torque to the input shaft 18.
The M/G 14 may also act as a generator and convert kinetic energy from the powertrain 12 into electric energy to be stored in the battery 22. More specifically, the M/G 14 may act as a generator during times of regenerative braking in which torque and rotational (or kinetic) energy from the spinning wheels 28 is transferred back through the transmission 16 and is converted into electrical energy for storage in the battery 22.
It should be understood that the vehicle configuration described herein is merely exemplary and is not intended to be limited. Other electric or hybrid electric vehicle configurations should be construed as disclosed herein. Other electric or hybrid vehicle configurations may include, but are not limited to, series hybrid vehicles, parallel hybrid vehicles, series-parallel hybrid vehicles, plug-in hybrid electric vehicles (PHEVs), fuel cell hybrid vehicles, battery operated electric vehicles (BEVs), or any other vehicle configuration known to a person of ordinary skill in the art.
In hybrid configurations that include an internal combustion engine such as a gasoline, diesel, or natural gas powered engine, or a fuel cell, the controller 32 may be configured to control various parameters of such an internal combustion engine. Representative examples of internal combustion parameters, systems, and/or components that may be directly or indirectly actuated using control logic and/or algorithms executed by the controller 32 include fuel injection timing, rate, and duration, throttle valve position, spark plug ignition timing (for spark-ignition engines), intake/exhaust valve timing and duration, etc. Sensors communicating input through the I/O interface from such an internal combustion engine to the controller 32 may be used to indicate turbocharger boost pressure, crankshaft position (PIP), engine rotational speed (RPM), intake manifold pressure (MAP), throttle valve position (TP), exhaust gas oxygen (EGO) or other exhaust gas component concentration or presence, intake air flow (MAF), etc.
It should be understood that the schematic illustrated in
As the range of electric vehicles increases, more battery cells may be connected in parallel in battery packs. If one or more cells are experiencing thermal runaway, where the temperature of the cell is significantly increasing to levels higher than operable temperatures, electrical energy may transfer from the other cells to a cell that is experiencing the thermal runaway, resulting in further temperature increases in the cell experiencing the thermal runaway. Some of the heat from the cell that is experiencing thermal runaway may then be transferred to the other cells through the parallel connections. In order to slow down such thermal propagation between the battery cells, insulating materials may be disposed between cells. The configuration disclosed herein, includes a thermal barrier that significantly slows down thermal propagation between the battery cells, which is particularly advantageous if when one or more of the cells are experiencing thermal runaway.
Referring to
Thermal barriers 56 may be disposed between adjacent cell banks 44. The thermal barriers may also be disposed between subsets of cells 42 within a single cell bank 44. The battery may also include end plates 58. Thermal barriers 56 may also be disposed between the end plates 58 and an adjacent cell 42. The thermal barriers 56 may be comprised of an insulating material that is configured to restrict heat transfer, an endothermic material that is configured to absorb heat, or a combination of such materials. The properties and composition of the thermal barriers 56 may vary within the battery 22. For example, some of the thermal barriers 56 may only include an insulating material, some thermal barriers 56 may only include an endothermic material, and some thermal barriers 56 may include both insulating and endothermic materials. The battery 22 may also include a heating pad 60 that is configured to warm the battery 22 when the temperature is below optimum operating temperatures.
Referring to
The thermal barriers 56 disposed between end plates 58 and one of the cells 42 may be referred to as outer thermal barriers 66. The outer thermal barriers 66 may be made from an insulating material that operates to reduce heat transfer between the battery 22 and the exterior of the battery 22, such as an insulating foam (e.g., polyurethane foam). The thermal barrier 56 that is disposed between the bottom plate 62 and the cells 42 may be referred to as the bottom thermal barrier 68. The bottom thermal barrier 68 may also be made from an insulating material that operates to reduce heat transfer between the battery 22 and the exterior of the battery 22, such as an insulating foam (e.g., polyurethane foam). The thermal barrier 56 that is disposed between the cover 64 and the cells 42 may be referred to as the top thermal barrier 70. The top thermal barrier 70 may be made from a material having endothermic and intumescent properties (e.g., an endothermic and intumescent aerogel), which is configured to absorb heat and expand as the heat is absorbed. The thermal barriers 56 disposed between adjacent cells 42 or between adjacent cell banks 44 may be referred to as intermediate thermal barriers 72. The intermediate thermal barriers 72 may be made from a combination of insulating materials (e.g., polyurethane foam) and materials having endothermic and intumescent properties (e.g., an endothermic and intumescent aerogel).
Referring to
The first thermal insulator 76 and the second thermal insulator 78 of each intermediate thermal barrier 72 may more specifically be disposed on and engage the exterior surfaces 74 of the adjacent cells 42. The endothermic and intumescent layer 80 may be exterior the first thermal insulator 76 relative the cell 42 that is adjacent and secured to the first thermal insulator 76 such that the first thermal insulator 76 is disposed between the said adjacent cell 42 and the endothermic and intumescent layer 80. The endothermic and intumescent layer 80 may also be exterior the second thermal insulator 78 relative the cell 42 that is adjacent and secured to the second thermal insulator 78 such that the second thermal insulator 78 is disposed between the said adjacent cell 42 and the endothermic and intumescent layer 80.
The endothermic and intumescent layer 80 is configured to, in response to an increase in temperatures of the adjacent cells 42 and heat generated by adjacent cells 42 consuming the first thermal insulator 76 and the second thermal insulator 78, (i) expand, (ii) engage the adjacent cells 42 (e.g., contact the exterior surfaces 74 of adjacent cells 42), and (iii) absorb the heat generated by the adjacent cells 42. The endothermic and intumescent layer 80 is also configured to, in response to the increase in the temperatures of the adjacent cells 42 and the heat generated by the adjacent cells 42 not consuming the first thermal insulator 76 and the second thermal insulator 78, (i) expand, (ii) compress and displace first thermal insulator 76 and the second thermal insulator 78, and (iii) absorb the heat generated by the adjacent cells 42. It is noted that the endothermic and intumescent layer 80 may alternatively only expand into one of the first thermal insulator 76 or the second thermal insulator 78 if heat is only being transferred from one direction or if the endothermic and intumescent layer 80 is only secured to a single thermal insulator that is sandwiched between the endothermic and intumescent layer 80 and one of the cells 42.
During thermal runaway of one or more cells 42, the first thermal insulator 76 and the second thermal insulator 78 may be consumed at a temperature that is above a threshold value. The endothermic and intumescent layer 80 will then absorb heat and uniformly expand to occupy empty space created due to consumption of the first thermal insulator 76 and the second thermal insulator 78. The expansion and heat absorption of the endothermic and intumescent layer 80 will further reduce temperatures of neighboring or adjacent cells 42.
If the first thermal insulator 76 and the second thermal insulator 78 are polyurethane foam and if the endothermic and intumescent layer 80 is an endothermic and intumescent aerogel, the first thermal insulator 76 and the second thermal insulator 78 will be consumed at a temperature of approximately 135° C. The aerogel operates to further insulate the cells 42 at higher temperatures after the first thermal insulator 76 and the second thermal insulator 78 have been consumed due to the higher insulation capability of aerogel system (0.03 w/mk at 300° C.). Such an endothermic and intumescent aerogel is able to withstand temperatures of up to 1200° C. and has high heat absorption and high thermal resistance due to a low thermal conductivity at higher temperatures.
The first thermal insulator 76 and the second thermal insulator 78 may be elastic so that the expanding endothermic and intumescent layer 80 may compress the first thermal insulator 76 and the second thermal insulator 78. More specifically, the first thermal insulator 76 and the second thermal insulator 78 may have a Shore A durometer that ranges between thirty and forty.
Each intermediate thermal barrier 72 may also include protrusions or tabs 84 that extend outward from the intermediate thermal barriers 72. More specifically, the tabs 84 may extend upward and downward from top and bottom surfaces of the endothermic and intumescent layer 80. The tabs 84 may be part of seal that that retains the material of the endothermic and intumescent layer 80. The tabs 84 may also be coated with an endothermic and intumescent material 86, such as an endothermic and intumescent aerogel, which is also configured to expand and absorb heat generated by the cells 42.
The intumescent endothermic coating material 86 may activate when the battery cells 42 go into thermal runaway and the surrounding temperature exceeds a threshold. The intumescent endothermic coating material 86 may expand into the areas where there is no active cell material, hence will not affect operation neighboring battery cells. The intumescent endothermic coating material 86 also absorbs heat energy during thermal runaway events of one more of the cells 44 and may function to reduce or eliminate heat transfer between cells 42 via convection of hot gasses within voids defined with the battery 22.
Microcapsule sheets 88 may be disposed over one or more of the cells 42. Each microcapsule sheet 88 may be disposed over one cell 42 or subsets that include multiple cells 42. The microcapsule sheets 88 may be disposed over a portion of the cells 42, as illustrated in
The illustration of the battery 22 in
An advantage of utilizing the structure of the intermediate thermal barriers 72 between parallel cells 42 is that the intermediate thermal barriers 72 prolongs the time for electrical energy from the parallel cells 42 to transfer to a cell 42 that is experiencing thermal runaway. As a result, it takes longer for the next cell in the parallel configuration to go into thermal runaway. Furthermore, if the next cell 42 in the parallel configuration does go into thermal runaway, it will be at lower state of charge and therefore will have less stored energy to increase the temperature of the cell 42 during the thermal runaway event. Placing the intermediate thermal barriers 72 in the middle of a cell bank 44 also prolongs the time for heat to transfer through the thermally conductive connections, which results in a longer propagation time to transfer heat, or may even arrest thermal propagation between cells 42.
It should be understood that the designations of first, second, third, fourth, etc. for any component, state, or condition described herein may be rearranged in the claims so that they are in chronological order with respect to the claims. Furthermore, it should be understood that any component, state, or condition described herein that does not have a numerical designation may be given a designation of first, second, third, fourth, etc. in the claims if one or more of the specific component, state, or condition are claimed.
The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.