ELECTRIC VEHICLE BATTERY ASSEMBLY WITH TWO-PHASE VENT

The electric-vehicle battery assembly includes a battery enclosure defining a cavity and includes battery cells enclosed by the battery enclosure in the cavity. An outlet extends through the battery enclosure and in fluid communication with the cavity. A vent includes a frame moveably supported by the battery enclosure. The frame is moveable relative to outlet between an open position allowing fluid flow from the cavity between the outlet and the frame and a closed position preventing fluid flow from the cavity between the outlet and frame. The vent includes a microporous membrane supported by the frame.

BACKGROUND

A battery-electric vehicle includes one or more batteries (i.e. electric-vehicle batteries) that power the vehicle, including propulsion of the vehicle. For example, wheels of the vehicle are powered by electric motors that are powered by the electric-vehicle batteries. The electric-vehicle batteries may also power lighting, electronics, etc. The electric-vehicle battery may be stored in a battery compartment that may be, for example, under a passenger cabin of the vehicle.

The electric-vehicle battery includes battery cells enclosed in a battery enclosure. In such an example, the battery cells are stacked in the battery enclosure. As one example, the battery cells may be lithium-ion battery cells. Under certain conditions, one or more of the battery cells may release gas and/or heat. This increases the pressure and the temperature in the battery enclosure.

The battery cells have operating temperatures. In the event that the temperature of one of the battery cells exceeds the operating temperature, the battery cell may enter a thermal condition. In such an event, a chain reaction in the battery cell causes a rapid generation of heat and this this temperature rise of the battery causes gassing, i.e., release of gas from the battery cell. This increase in temperature of the battery cell and emission of gas by the battery cell increases the temperature and pressure of the battery enclosure. In some situations, this increase in temperature and pressure of the battery enclosure and/or the increase in temperature of the battery cell itself may cause one or more adjacent battery cells to also exceed the operating temperature and enter a thermal condition and, in some situations, this may cause a chain reaction of battery cells entering the thermal condition. After a thermal condition, the battery cells may be irreversibly damaged and inoperative thereafter.

DETAILED DESCRIPTION

An electric-vehicle battery includes a battery enclosure defining a cavity, battery cells enclosed by the battery enclosure in the cavity, and an outlet extending through the battery enclosure and in fluid communication with the cavity. A vent includes a frame moveably supported by the battery enclosure. The frame is moveable relative to outlet between an open position allowing fluid flow from the cavity between the outlet and the frame and a closed position preventing fluid flow from the cavity between the outlet and frame. The vent includes a microporous membrane supported by the frame.

The microporous membrane may be expanded polytetrafluoroethylene (ePTFE).

The vent may include a spring biasing frame toward the closed position.

The frame may seal to the battery enclosure in the closed position. The frame may define an opening in fluid communication with the outlet and the microporous membrane may cover the opening. The outlet may have an axis and the opening may be on the axis.

The frame may define an opening and the microporous membrane may cover the opening.

The frame may seal to the battery enclosure in the closed position and the frame may be spaced from the battery enclosure in the open position. The vent may include a fitting extending through the battery enclosure, and the fitting may define the outlet. A sealing surface of the frame may abut the fitting and may be sealed to the fitting to seal to the battery enclosure in the closed position and the sealing surface may be spaced from the fitting in the open position.

The frame may be rigid relative to the microporous membrane.

The frame may be rotatably coupled to the battery enclosure and the frame may be rotatable relative to the battery enclosure between open position and the closed position.

The vent may include a fitting extending through the battery enclosure and the fitting may define the outlet. The frame may define an opening in fluid communication with the outlet and the microporous membrane may cover the opening. The outlet may have an axis and the opening is on the axis. The frame may define an opening and the microporous membrane may cover the opening. A sealing surface of the frame may abut the fitting and may be sealed to the fitting in the closed position and the sealing surface may be spaced from the fitting in the open position. The frame may be rotatably coupled to the fitting.

A fan may be adjacent the vent between the vent and the cavity. The fan may be operable to move the vent to the open position. A controller may have a processor and memory storing instructions executable by the processor to activate the fan in response to detection of pressure in the cavity above a predetermined threshold.

With reference to the Figures, wherein like numerals indicate like parts throughout the several views, an electric-vehicle battery assembly12is generally shown. The electric-vehicle battery assembly12includes a battery enclosure14defining a cavity16and includes battery cells18enclosed by the battery enclosure14in the cavity16. An outlet30extends through the battery enclosure14and in fluid communication with the cavity16. A vent22includes a frame24moveably supported by the battery enclosure14. The frame24is moveable relative to outlet30between an open position allowing fluid flow from the cavity16between the outlet30and the frame24and a closed position preventing fluid flow from the cavity16between the outlet30and frame24. The vent22includes a microporous membrane26supported by the frame24.

The vent22provides two-phase venting to vent pressure build-up in the battery enclosure14. Specifically, in the event of pressure increase in the cavity16exceeding ambient pressure exterior to the battery enclosure14, the microporous membrane26allows fluid flow across the microporous membrane26to vent pressure from the cavity16. In a first phase of venting, in the event the pressure increase in the cavity16is insufficient to move the vent22from the closed position to the open position, the vent22remains in the closed position while pressure equilibrates across the microporous membrane26. In a second phase of venting, in the event the pressure increase in the cavity16is sufficient to move the vent22to the open position, the pressure moves the vent22to the open position and pressure is released from the cavity16to the environment around the battery enclosure14. This venting reduces the pressure and temperature of the cavity16of the battery enclosure14.

With reference toFIG.1, the vehicle10may be any suitable type of automobile, e.g., a passenger or commercial automobile such as a sedan, a coupe, a truck, a sport utility, a crossover, a van, a minivan, a taxi, a bus, etc. In some examples, the vehicle10may be autonomous. In other words, the vehicle10may be autonomously operated such that the vehicle10may be driven without constant attention from a driver, i.e., the vehicle10may be self-driving without human input. The vehicle10, specifically the electric-vehicle battery assembly12, includes an electric-vehicle battery28that powers propulsion of the vehicle10, e.g., the vehicle10may be battery-electric (BEV), hybrid electric, plug-in hybrid electric (PHEV), etc.

With reference toFIG.1, the vehicle10defines a vehicle-longitudinal axis L extending between a front end (not numbered) and a rear-end (not numbered) of the vehicle10. The vehicle10defines a vehicle-lateral axis A extending cross-vehicle10from one side to the other side of the vehicle10. The vehicle10defines a vertical axis V extending through the floor and ceiling of the vehicle10. The vehicle-longitudinal axis L, the vehicle-lateral axis A, and the vertical axis V are perpendicular relative to each other.

With continued reference toFIGS.1, the vehicle10includes the vehicle frame. As one example, the vehicle frame may be of a unibody construction in which the vehicle frame is unitary with a vehicle body (including frame rails, pillars, roof rails, etc.). As another example, the vehicle body and the vehicle frame may have a body-on-frame24construction (also referred to as a cab-on-frame24construction) in which the vehicle body and the vehicle frame are separate components, i.e., are modular, and the vehicle body is supported on and affixed to the vehicle frame. In other examples, the vehicle frame and the vehicle body may have any suitable construction. The vehicle frame and the vehicle body may be of any suitable material, for example, steel, aluminum, and/or fiber-reinforced plastic, etc.

The vehicle frame includes a frame rail on a left side of the vehicle10and a frame rail on a right side of the vehicle10. The frame rails may be tubular. The frame rails are spaced from each other along the cross-vehicle axis C. Specifically, the frame rails may define the vehicle outboard boundaries of the vehicle frame. The first frame rail and the second frame rail may be aligned cross-vehicle10with wheel wells and wheels of the vehicle10, i.e., extending from one wheel well to another wheel well on a common side of the vehicle10. The vehicle10may include rockers30elongated along the vehicle-longitudinal axis L below doors of the vehicle10and extending along the frame rails, respectively. The rockers30may be fixed to and/or supported by the frame rails, respectively. The electric-vehicle battery assembly12including the battery enclosure14is disposed between the frame rails and/or between the rockers30.

The frame rails and rockers30are elongated in a vehicle-longitudinal direction, i.e., along the vehicle-longitudinal axis L. The frame rails may be elongated at least from one wheel well to another wheel well. In addition, the frame rails may extend forward of a front wheel well and rearward of a rear wheel well, e.g., by extending inboard and/or above the wheel well.

The electric-vehicle battery28may be of any suitable type for vehicular electrification, i.e., for powering propulsion of the vehicle10. For example, the electric-vehicle battery28may be lithium-ion batteries, nickel-metal hydride batteries, lead-acid batteries, or ultracapacitors, as used in, for example, plug-in hybrid electric vehicle10s (PHEVs), hybrid electric vehicle10s (HEVs), or battery electric vehicle10s (BEVs). The electric-vehicle10batteries may be arranged as battery modules. In examples including multiple battery modules, adjacent ones of the battery modules are connected to each other. Each battery module may include a plurality of battery cells18. The cavity16of the battery enclosure14may house the electric-vehicle10batteries.

The electric-vehicle battery assembly12includes the electric-vehicle battery28and the battery enclosure14. In examples including multiple battery modules, adjacent ones of the battery modules are connected to each other in the cavity16of the battery enclosure14. In such examples, each battery module may include a plurality of battery cells18. The battery assembly12may include any suitable hardware, e.g., wiring, connectors, circuits, etc., connecting the battery modules to each other and to electrified components of the vehicle10.

With reference toFIGS.1and2, the battery enclosure14defines the cavity16that houses the electric-vehicle battery28. The battery enclosure14may be plastic, metal, or any suitable material. The battery enclosure14is supported by the vehicle frame, e.g., by direct attachment or indirect attachment through another component.

The battery enclosure14extends from one frame rail to the other frame rail and/or from one rocker30to the other rocker30. The battery enclosure14may be continuous from the rail to rail. Specifically, the battery enclosure14may span the entire underbody of the vehicle10from one rail to the other rail. The battery enclosure14supports one or more electric-vehicle batteries28, as described further below. The battery enclosure14supports hardware associated with the electric-vehicle battery28such as wiring, cooling hardware, mounting hardware, etc.

With continued reference toFIGS.1and2, the battery enclosure14is sized and shaped to enclose the electric-vehicle battery28. As an example, the battery enclosure14may include a first side member32and a second side member34. The first side member32and the second side member34may define outboard boundaries of the battery enclosure14, as shown in the example in the Figures. The battery enclosure14may include a front wall36, a rear wall38, a bottom panel40, and/or a top panel42each extending from the first side member32and the second side member34. The bottom panel40may be exposed to the road surface and may prevent intrusion of precipitation and dirt to the battery cells18. The top panel42may separate the battery compartment from components of the vehicle10above the battery enclosure14, e.g., a passenger compartment.

As set forth above, the battery enclosure14defines the cavity16. The battery28, specifically the battery cells18, are enclosed by the battery enclosure14in the cavity16. In other words, the cavity16is environmentally sealed by the battery enclosure14, i.e., to prevent intrusion of road precipitation and dirt. For example, in the example, shown in the Figures, the first side member32, second side member34, front wall36, rear wall38, bottom panel40, and top panel42enclose the electric-vehicle battery28. Specifically, the first side member32, second side member34, front wall36, rear wall38, bottom panel40, and top panel42are sealed to each other such that the battery enclosure14is environmentally sealed, i.e., to prevent intrusion of road precipitation and dirt. The bottom panel40and the top panel42may be fixed to the first side member32, the second side member34, the front wall36, and/or the rear wall38, e.g., welding, adhesive, bonding, unitary formation, etc. In such examples, the first side member32, the second side member34, front wall36, rear wall38, bottom panel40, and top panel42may be hermetically sealed to each other and formed of material that prevents fluid flow therethrough. In other examples, at least one of the first side member32, the second side member34, front wall36, rear wall38, bottom panel40, and top panel42may include a second microporous membrane to allow for pressure equilibration, in conjunction with the vent22described further below, for instances in which pressure builds in the cavity16. In such examples, the second microporous membrane may be of the same type of material as the microporous membrane26of the vent22.

The battery enclosure14defines, at least in part, an outlet30extending through the battery enclosure14and in fluid communication with the cavity16. In the event of pressure increase in the cavity16above the pressure of the environment exterior to the battery enclosure14, the vent22allows for pressure equilibration between the cavity16and the environment exterior to the battery enclosure14. In the example shown in the Figures, the outlet30extends through the top panel. In other examples, the outlet30may extend through any one of the first side member32, the second side member34, front wall36, rear wall38, bottom panel40, and/or top panel42. In the example shown in the Figures, the electric-vehicle battery assembly12includes one outlet30and one vent22and, in other examples, the battery assembly12may include more than one outlet30and respective vent22in any one or combination of the first side member32, second side member34, front wall36, rear wall38, bottom panel40, and/or top panel42.

As set forth above, the vent22provides two-phase venting to vent pressure buildup in the battery enclosure14to reduce pressure and temperature of the cavity16of the battery enclosure14. In the first phase of venting, in the event the pressure increase in the cavity16is insufficient to move the vent22from the closed position to the open position, the vent22remains in the closed position while pressure equilibrates across the microporous membrane26. In the event that the pressure buildup in the cavity16exceeds the pressure equilibration across the microporous membrane26, the vent22may enter the second phase of venting. In the second phase of venting, the pressure increase in the cavity16is sufficient to move the vent22to the open position and the pressure moves the vent22to the open position. In the open position, the vent22releases pressure from the cavity16through the outlet30to the environment around the battery enclosure14. This venting reduces the pressure and temperature of the cavity16of the battery enclosure14.

As set forth above, in the open position, the vent22releases pressure from the cavity16through the outlet30to the environment around the battery enclosure14. Specifically, the frame24of the vent22and the microporous membrane26is moved to the open position, as described below, opening58a flow path through the vent22that circumvent22s flow through the microporous membrane26. In the open position, resistance to flow through the vent22is less than in the closed position.

As set forth above, the vent22includes the frame24and the microporous membrane26. Specifically, the vent22includes a vent body44and a vent seat46. The vent body44includes the frame24and the microporous membrane26. The vent body44, i.e., the frame24and/or the microporous membrane26, seals the outlet30from the environment exterior to the battery enclosure14in the closed position and opens the outlet30to the environment exterior to the battery enclosure14in the open position, as described further below.

The vent22may include more than one vent body44. In the example shown in the Figures, the vent22includes four vent bodies44. In such an example, each vent body44includes at least one frame24and at least one microporous membrane26. The frame24, for example, may be plastic, metal, composite, or any other suitable material.

The microporous membrane26is supported by the frame24. In other words, the weight of the microporous membrane26is borne by the frame24. Accordingly, the microporous membrane26moves with the frame24as the frame24moves between the open position and the closed position, as described further below. The frame24may be rigid relative to the microporous membrane26. In other words, the frame24may maintain shape and the microporous membrane26may flex relative to the frame24when subjected to certain forces. In instances in which the pressure in the cavity16is sufficient to move the vent22to the open position, the frame24moves to the open position and the microporous membrane26moves with the frame24.

The microporous membrane26is air-permeable. Accordingly, the microporous membrane26allows for pressure in the cavity16and pressure exterior to the battery enclosure14to equilibrate across the vent22at a rate commensurate with the permeability of the microporous membrane26, i.e., in the first phase of venting. The microporous membrane26includes holes, e.g., pores, channels, etc., that allow for fluid flow and limit or prevent passage of dirt and precipitation across the microporous membrane26. The holes may have a diameter in the nanometer range, i.e., less than 1 micrometer. As an example, the holes may have a diameter less than 10 nanometers. The microporous membrane26, for example, may be a sheet having the holes. The holes may be formed, for example, during the formation of the material of the sheet of the microporous membrane26. As an example, the microporous membrane26may be expanded polytetrafluoroethylene (ePTFE). As another example, the microporous membrane26may be fabric. In such examples, the microporous membrane26includes woven fibers defining the holes between the fiber. The microporous membrane26may have any suitable thickness to vent in the first stage of venting as described above.

The vent22may include a fitting48. In such examples, the fitting48extends through the battery enclosure14. The fitting48and the battery enclosure14in combination define the outlet30. The outlet30extends through both the fitting48and the battery enclosure14. In the example shown in the Figures, the fitting48includes a flange50and a throat52. The flange50abuts the battery enclosure14. The outlet30extends through the throat52. The fitting48may be fixed to the battery enclosure14in any suitable fashion such as welding, adhesive, bonding, unitary formation, etc. The connection between the fitting48and the battery enclosure14is sealed and impermeable to airflow.

The vent body44, and specifically the frame24, is moveably supported by the battery enclosure14. In other words, the weight of the frame24is borne by the battery enclosure14. For example, the frame24may be directly or indirectly supported by the battery enclosure14. In the example shown in the Figures, the frame24is supported directly by the fitting48and the frame24is supported indirectly, i.e., through the fitting48, by the battery enclosure14.

The frame24is moveable relative to the outlet30between an open position allowing fluid flow from the cavity16between the outlet30and the frame24and a closed position preventing fluid flow from the cavity16between the outlet30and frame24. In the example shown in the Figures, the frame24is moveable relative to the fitting48and the battery enclosure14between closed position and the open position.

In one example, such as the example shown the Figures, the frame24is rotatably coupled to the battery enclosure14, the frame24being rotatable relative to the battery enclosure14between open position and the closed position. For example, as shown in the example shown in the Figures, the frame24is rotatably coupled to the battery enclosure14through the fitting48, i.e., is indirectly coupled to the battery enclosure14. Specifically, in such an example, the frame24is rotatably coupled to the fitting48, e.g., the flange50as shown in the example shown in the Figures. In the example shown in the Figures, the vent22includes a hinge54between the frame24and the fitting48, e.g., the flange50. The hinge54may be of any suitable type such as, for example, a butt hinge.

The vent22may be spring-loaded. For example, the vent22may include a spring56biasing the frame24toward the closed position. In the example shown in the Figures, the hinge54may be spring-loaded. Specifically, the spring56may be grounded to the fitting48and the frame24of the vent22and may be positioned to bias the frame24toward the closed position. In the example shown in the Figures, the hinge54is a spring-loaded butt hinge. In the event the pressure increase in the cavity16is insufficient to overcome the bias of the spring56, the vent22remains in the closed position while pressure equilibrates across the microporous membrane26. In the event the pressure increase in the cavity16is sufficient to overcome the bias of the spring56, the pressure rotates the vent22to the open position against the bias of the spring56. When pressure in the cavity16decreases, due to venting, the spring56returns the vent22to the closed position.

As set forth above, the frame24and/or the microporous membrane26seals the outlet30from the environment exterior to the battery enclosure14in the closed position and opens the outlet30to the environment exterior to the battery enclosure14in the open position. In the closed position, the microporous membrane26vents in the first phase of venting as described above. In the open position, the vent22allows flow through the outlet30from the without passing through the microporous membrane26.

The frame24defines an opening58in fluid communication with the outlet30, the microporous membrane26covers the opening58. As an example, the outlet30has an axis O and the opening58is on the axis O when the vent22is in the closed position. In the closed position the frame24of the vent22is sealed to the battery enclosure14, as described below, and the opening58of the frame24is exposed to the outlet30so that air flows through the opening58and the microporous membrane26. Specifically, for pressure build-up in the cavity16that is insufficient to move the vent22to the open position, gas flows through the opening58the microporous membrane26.

The frame24seals to the battery enclosure14in the closed position. In other words, the frame24in the closed position prevents fluid flow between the frame24and the battery enclosure14. The frame24is spaced from the battery enclosure14in the open position to allow for fluid flow between the frame24and the battery enclosure14.

In the example shown in the Figures, vent seat46is on the fitting48and, in the closed position, a sealing surface60of the frame24abuts the fitting48and is sealed to the fitting48, specifically the vent seat46, to seal to the battery enclosure14in the closed position. In such an example, the sealing surface60is spaced from the fitting48, specifically the vent seat46, in the open position. In the example shown in the Figures in which the fitting48includes more than one vent body44, the fitting48includes cross-beams62extending across the outlet30, e.g., transverse to the outlet30, such as perpendicular to the axis O of the outlet30as shown in the example in the Figures. In such an example, the vent seat46extends along the flange50and the cross-members62, and the frame24abuts both the flange50and the cross-members62in the closed position. The sealing surface60of the frame24and/or the vent seat46in the closed position may include a seal (not shown) of a material to encourage sealing between the frame24and fitting48, e.g., rubber.

The electric-vehicle battery assembly12may include a fan64for blowing air through the outlet30from the cavity16to the environment exterior to the battery enclosure14when the vent22is open. The fan64may be between the vent22and the cavity16. For example, the fan64may be adjacent the vent22, i.e., with the absence of any other component between the fan64and the vent22. The fan64may be in the outlet30. The fan64may be of any suitable type, e.g., a propeller fan, a centrifugal fan, or any suitable type of fan64. The fan64includes a motor72and a blade74. The blade74may be a propeller, impeller, etc.

In examples including the fan64, the fan64may be operable to move the vent22to the open position. In such an example, the operation of the fan64moves the vent22to the open position. As an example, an exhaust side of the fan64may be pointed at the vent22such that exhaust from the fan64urges the vent22to move from the closed position toward the open position. In examples including the spring56in the hinge54, as shown in the Figures, the pressure at the exhaust side of the fan64is of a magnitude and location to move the vent22to the open position against the bias of the spring56when the fan64is operated.

The vehicle10may include a controller66having a processor and a memory storing instructions executable by the processor to control operation of the fan64. The controller66may be, for example, a battery control module. Use of “in response to,”“based on,” and “upon determining” herein indicates a causal relationship, not merely a temporal relationship.

The vehicle10may include a pressure sensor68for measuring the temperature of the cavity16of the battery enclosure14. The pressure sensor68may, for example, be in the cavity16of the battery enclosure14. The pressure sensor68may be of any suitable type for measuring the pressure of the cavity16with sufficient sensitivity to detect pressure increase before a thermal condition.

The controller66has a processor and memory storing instructions executable by the processor to activate the fan64in response to detection of pressure in the cavity16above a predetermined threshold. For example, the controller66may activate the fan64in response to detection of pressure above the threshold by the pressure sensor68. The predetermined threshold of pressure in the cavity16may, for example, be determined empirically or in any other suitable fashion. As set forth above, when the fan64is activated, the fan64may move the vent22to the open position.

The controller66in the Figures illustrates an example storage medium. Storage medium may be any non-transitory computer-readable storage medium or machine-readable storage medium, such as an optical, magnetic or semiconductor storage medium. In various implementations, storage medium may be an article of manufacture. In some implementations, storage medium may store computer-executable instructions, such as computer-executable instructions to implement logic flow. Examples of a computer-readable storage medium or machine-readable storage medium may include any tangible media capable of storing electronic data, including volatile memory or non-volatile memory, removable or non-removable memory, erasable or non-erasable memory, writeable or re-writeable memory, and so forth. Examples of computer-executable instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, object-oriented code, visual code, and the like.

The vehicle10includes a communication network70that can include a bus in the vehicle10such as a controller area network (CAN) or the like, and/or other wired and/or wireless mechanisms. Via the vehicle network70, the controller66may transmit messages to various devices in the vehicle10and/or receive messages (e.g., CAN messages) from the various devices, e.g., sensors, an actuator, a human machine interface (HMI), etc. Alternatively or additionally, in cases where the controller66comprises a plurality of devices, the vehicle communication network70may be used for communications between devices represented as the controller66in this disclosure. Further, as mentioned below, various controllers and/or sensors may provide data to the controller via the vehicle communication network70.