BATTERY PACK VENTING ASSEMBLY AND VENTING PROCEDURE

Abstract

A battery pack vent assembly includes a battery pack vent that channels a stream of venting byproducts from a battery pack. The battery pack vent has a coolant passage that channels a coolant to manage thermal energy levels within the stream of venting byproducts. The coolant can be a liquid. The battery pack vent can be configured to channel the stream so that it impacts areas of the battery pack vent.

Description

FIELD OF TECHNOLOGYThis disclosure relates generally to draining vent byproducts from a traction battery pack, and more particularly to cooling the vent byproducts prior to draining.GENERAL STATE OF THE ARTElectrified vehicles are distinct from conventional motor vehicles because electrified vehicles are selectively propelled using one or more electric machines powered by a traction battery. The electric machines may propel the electrified vehicles instead of or in addition to an internal combustion engine. The electrified vehicles include, for example, hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), fuel cell vehicles (FCV), and battery electric vehicles (BEV).SUMMARYIn some aspects, the techniques described herein relate to a battery pack venting assembly including: a battery pack venting opening that communicates a stream of venting byproducts from a battery pack, the battery pack venting opening having a coolant passage that communicates coolant to manage thermal energy levels within the stream of venting byproducts.In some aspects, the techniques described herein relate to a battery pack vent assembly, wherein the battery pack vent includes a first ring and a second ring located radially outward of the first ring, wherein the battery pack vent further includes at least one support web extending radially from the first ring to the second ring.In some aspects, the techniques described herein relate to a battery pack venting assembly wherein the coolant passage extends through the first ring, the second ring, and the at least one support web.In some aspects, the techniques described herein relate to a battery pack vent assembly, wherein the battery pack vent further includes a third ring located radially outward of the second ring, wherein the battery pack vent further includes at least one support web extending radially from the second ring to the third ring, wherein the coolant passage additionally extends through the third ring, and the at least one support web extends radially from the second ring to the third ring.In some aspects, the techniques described herein relate to a battery pack venting assembly, wherein the first ring includes a plurality of first ring openings that allow venting byproducts to flow radially from a position radially inward of the first ring to a position radially outward of the first ring.In some aspects, the techniques described herein relate to a battery pack venting assembly, wherein the second ring includes a plurality of second ring openings that allow venting byproducts to flow radially from a position radially inward of the second ring to a position radially outward of the second ring.In some aspects, the techniques described herein relate to a battery pack vent assembly, wherein the plurality of first ring openings are circumferentially offset from the plurality of second ring openings about an axis of the battery pack vent opening.In some aspects, the techniques described herein relate to a battery pack venting assembly, wherein the coolant is a liquid coolant.In some aspects, the techniques described herein relate to a battery pack vent assembly, wherein the battery pack vent is made of a metal or metal alloy.In some aspects, the techniques described herein relate to a battery pack vent assembly, wherein the battery pack vent is attached to a housing of the battery pack.In some aspects, the techniques described herein relate to a battery pack vent assembly wherein the flow of vent byproducts is discharged radially from the battery pack vent opening.In some aspects, the techniques described herein relate to a method of venting from a battery pack, including: receiving a stream of venting byproducts at a battery pack vent; managing thermal energy within the stream of venting byproducts using a coolant routed through the battery pack vent; and draining the stream of venting byproducts from the battery pack vent.In some aspects, the techniques described herein relate to a method further including passing the vent byproducts within the battery pack vent between a first ring and a second ring of the battery pack vent.In some aspects, the techniques described herein relate to a method wherein the coolant is routed through at least one coolant passage within the first ring, within the second ring, or both.In some aspects, the techniques described herein relate to a method wherein the first ring and the second ring are coaxially disposed about a vent axis.In some aspects, the techniques described herein relate to a method further including directing the flow of vent byproducts within the battery pack vent opening radially through at least one first ring opening in the first ring such that the flow of vent byproducts impinges on the second ring and then flows between the first ring and the second ring.In some aspects, the techniques described herein relate to a method further including directing the flow of venting byproducts radially through at least one second ring opening in the second ring.In some aspects, the techniques described herein relate to a method wherein the coolant is a liquid coolant.In some aspects, the techniques described herein relate to a method further including deriving the vent byproducts radially from the battery pack vent opening.In some aspects, the techniques described herein relate to a method further including draining the vent byproducts axially from the battery pack vent opening through an annular outlet.The embodiments, examples and alternatives of the preceding paragraphs, the claims or the following description and drawings, which include any of their various aspects or respective individual features, may be considered independently of one another or in any combination. Features described in connection with an embodiment are applicable to all embodiments, unless such features are incompatible.BRIEF DESCRIPTION OF THE FIGURESThe various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures attached to the detailed description may be briefly described as follows: FIG. 1 illustrates a side view of an electric vehicle having a traction battery pack. FIG. 2 illustrates a perspective enlarged view of the traction battery pack of FIG. 1. FIG. 3 illustrates a battery pack vent opening from the traction battery pack of FIG. 2 as viewed from inside to outside of the traction battery pack. FIG. 4 illustrates a schematic view of the battery pack of FIG. 2. FIG. 5 illustrates a side elevational view of the battery pack vent of FIG. 3. FIG. 6 illustrates a sectional view taken along line 6- 6 in FIG. 5. FIGS. 7A-7C illustrate sectional views taken along lines 7A-7A, 7B-7B, and 7C-7C in FIG. 6. FIGS. 8A-8C illustrate cross-sectional views through a vent according to another exemplary aspect of the present disclosure. FIG. 8D illustrates an end view of the vent of FIGS. 8A-8C. FIGS. 9A and 9B illustrate other cross-sectional views through the vent of FIGS. 8A-8D.DETAILED DESCRIPTIONThis disclosure relates generally to a traction battery pack of an electrified vehicle, and more particularly to a battery pack vent that cools and then discharges vent byproducts from the traction battery pack.Referring to FIG. 1, an electrified vehicle 10 includes a traction battery pack 12, an electric machine 14, and wheels 16. The battery pack 12 powers an electric machine 14 that converts the electric power to torque for driving the wheels 16. The battery pack 12 is a traction battery pack because the battery pack 12 is used for electric propulsion.The battery pack 12 is secured to an underbody 18 of the electrified vehicle 10 below and outside a passenger compartment of the electrified vehicle 10 in the exemplary embodiment. The battery pack 12 could be elsewhere on the electrified vehicle 10 in other examples.The example vehicle 10 is a battery electric vehicle (BEV). In another example, the vehicle 10 could be another type of electrified vehicle, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a traditional vehicle. A hybrid electric vehicle selectively drives wheels using torque provided by an internal combustion engine instead of or in addition to an electric machine. In general, the electrified vehicle 10 could be any type of vehicle that includes a traction battery pack.With reference to FIGS. 2 and 3, and with continued reference to FIG. 1, the battery pack 12 includes a plurality of battery banks 20 housed within an interior space 22 of a housing 24. The battery banks 20 each include groups of individual battery cells 26 arranged in rows. In one embodiment, the battery cells 26 are lithium ion pouch cells. Alternatively, however, battery cells having other geometries (cylindrical, prismatic, etc.), other chemical compositions (nickel-metal hydride, lead-acid, etc.), or both could be utilized within the scope of this disclosure.From time to time, due to a thermal propagation event, for example, due to overcharging or discharging, pressure and temperature in one of the battery cells 26 may increase. Thermal propagation events could also be due to internal contamination, battery cell deformation, or electrical shorts. The increasing pressure and temperature may break a vent opening 28 of the battery cell 26 and release vent byproducts V from an interior of the battery cell 26 into the interior 22. Although FIG. 2 shows a single fractured vent 28A, more than one of the battery cells 26 may vent simultaneously.Some battery cells 26, such as pouch cells, may not include their own vent, but may crack in various areas due to a thermal spreading event. The fracture provides a passage opening considered a vent opening. Venting byproducts V discharged through a through-opening created by a fracture are also considered venting byproducts V for purposes of this disclosure.In this example, the housing 24 includes a tray 32 and a cover 34. the tray 32 includes sidewalls 36 and a bottom 38.In this exemplary embodiment, at least one battery pack vent 40 is secured to the housing 24. The battery pack vent 40 may be a vent tip in some examples.The battery pack vent 40 communicates the vent byproducts V from the interior 22 of the battery pack 12 to an environmental region located outside of the battery pack 12. For purposes of this disclosure, environmental regions are regions located outside of the battery pack 12, outside of the passenger compartment of the vehicle 10, and, if present, outside of an engine compartment or trunk of the vehicle 10. Ambient air refers to the air within the surrounding areas. A temperature of the ambient air is typically much lower than a temperature of the ventilation byproducts V within the interior space 22.Referring to FIGS. 4-6, in this example, the battery pack vent 40 includes a first ring 44A, a second ring 44B, and a third ring 44C that are coaxially disposed about a vent axis A. Support webs 46A extend from the first ring 44A to the second ring 44B that is located radially outward of the first ring 44A. The support webs 46B extend radially from the second ring 44B to the third ring 44C that is located radially outward of the second ring 44B.In other examples, the vent 40 may include more than three rings or less than three rings. The vent 40 may be made of a metal or metal alloy material.With reference to FIGS. 7A-7C and with continued reference to FIGS. 2-5, the vent opening 40 includes a coolant passage 50 extending from a coolant inlet 52 to a coolant outlet 54 to manage thermal energy of the vent byproducts V. The coolant passage 50 extends through the first ring 44A, the second ring 44B, and the third ring 44C in this example. The coolant passage 50 additionally extends through the support webs 46A and the support webs 46B. The coolant passage 50 may have a diameter of two to five millimeters. In other examples, the coolant passage 50 may be less than two millimeters in some examples.A coolant C, such as a liquid coolant, may travel along a coolant path 56 through the inlet 52 into the coolant passage 50. The coolant C may exit the vent 40 through the outlet 54. From the outlet 54, the coolant C may move to a heat exchange device 58, such as a heat exchanger, and then to a coolant supply 60. A pump 62 may draw coolant C cooled at the heat exchange device 58 from the coolant supply 60 and circulate the coolant C back into the battery cell vent 40 through the inlet 52.During a thermal event, the vent byproducts V may move from the interior 22 into the vent opening 40. Specifically, the vent byproducts V flow into the first ring 44A of the vent opening 40 in a first axial direction. the vent byproducts V then move radially outward from the axis A through a plurality of first ring openings 66A within the first ring 44A. The first ring openings 66A allow venting byproducts to flow radially from a position radially inward of the first ring 44A to a position radially outward of the first ring 44A.After passing through the first ring opening 66A, the vent byproducts V are radially between the first ring 44A and the second ring 44B. It should be noted that the vent byproducts V impact a radially inner surface of the second ring 44B as the vent byproducts V are directed through the first ring opening 66A (FIG. 7A ). The impact may facilitate cooling the venting byproducts with the coolant C circulating through the coolant passage 50.Upon impact against the second ring 44B, at least some of the vent byproducts V turn and flow in an opposite, second axial direction. The vent byproducts V also flow circumferentially about the axis A between the first ring 44A and the second ring 44B and then travel through second ring openings 66B that are circumferentially offset about the axis A with respect to the first ring openings 66A.The second ring openings 66B allow venting byproducts V to flow radially from a position radially inward of the second ring 44B to a position radially outward of the second ring 44B.After the vent byproducts V pass the second ring openings 66B, B vent byproducts impinge on the inner surface of the third ring 44C (FIG. 7B ). The impact of the vent byproducts V against the inner surface of the third ring 44C may facilitate cooling of the vent byproducts V as the coolant C moves through the coolant passage 50 within the third ring 44C.The vent byproducts V then flow circumferentially until they exit the vent opening 40 through a plurality of third ring openings 66C within the third ring 44C (FIG. 7A ).As the vent byproducts V pass through the vent opening 40, the coolant C within the coolant passage 50 cools the vent byproducts to lower a thermal energy level within the vent byproducts V. In some examples, a temperature of the vent byproducts V may be reduced by more than 300 degrees Celsius before the vent byproducts move out of the vent opening 40 through the third ring openings 66C.While the pump 62 could continuously circulate coolant C through the coolant passage 50, the example pump 62 circulates coolant C only when one or more battery cells 26 are venting. The pump 62 could be activated to circulate coolant C through the coolant passage 50 of the vent 28 in response to a temperature in the interior 22 of the battery pack 12. For example, if a temperature sensor 70 in the interior 22 detects that a temperature has increased to, for example, greater than 200 degrees Celsius, a controller may activate the pump 62 to move coolant C through the vent 40. In such an example, a temperature greater than 200 degrees Celsius indicates that there is a high likelihood that at least one of the battery cells 26 will exhaust and expel venting byproducts V into the interior 22.While the example vent 40 ejects the vent byproducts V radially with respect to the axis A, other example vent openings may instead or additionally eject vent byproducts in other directions. For example, referring to FIGS. 8A-9D, another example vent opening 140 may expel vent byproducts V through an annular outlet 80. The vent byproducts V exit the vent hole 140 after being cooled by a coolant passing through a coolant passage 150.In the venting opening 40 and the venting opening 140, the supporting webs are aligned in the circumferential direction. In other examples, the support webs between a first innermost ring and a second intermediate ring could be circumferentially offset from the support webs between the second intermediate ring and a third outer ring.Features of the disclosed example vent openings include the ability to quickly cool vent byproducts prior to draining the vent byproducts.The foregoing description is exemplary and not limiting in nature. Variations and modifications of the disclosed examples may occur to those skilled in the art that do not necessarily depart from the gist of this disclosure. Accordingly, the scope of protection afforded by this disclosure may be determined only by studying the following claims.

Claims

A battery pack vent assembly comprising: a battery pack vent that communicates a stream of vent byproducts from a battery pack, the battery pack vent having a coolant passage that communicates a coolant to manage thermal energy levels within the stream of vent byproducts.The battery pack vent assembly of claim 1, wherein the battery pack vent includes a first ring and a second ring located radially outward of the first ring, the battery pack vent further including at least one support web extending radially from the first ring to the second ring.The battery pack venting assembly of claim 2, wherein the coolant passage extends through the first ring, the second ring, and the at least one support web, and optionally wherein the battery pack venting aperture further includes a third ring located radially outward of the second ring, wherein the battery pack venting aperture further includes at least one support web extending radially from the second ring to the third ring, wherein the coolant passage additionally extends through the third ring and the at least one support web extends radially from the second ring to the third ring.The battery pack venting assembly of claim 2, wherein the first ring includes a plurality of first ring openings that allow venting byproducts to flow radially from a position radially inward of the first ring to a position radially outward of the first ring, and optionally wherein the second ring includes a plurality of second ring openings that allow venting byproducts to flow radially from a position radially inward of the second ring to a position radially outward of the second ring.The battery pack vent assembly of claim 4, wherein the plurality of first ring openings are circumferentially offset from the plurality of second ring openings about an axis of the battery pack vent opening.The battery pack venting assembly of claim 1, wherein the coolant is a liquid coolant.The battery pack venting assembly of claim 1, wherein the battery pack venting aperture is made of a metal or metal alloy.The battery pack vent assembly of claim 1, wherein the battery pack vent is attached to a housing of the battery pack.The battery pack venting assembly of claim 1, wherein the flow of venting byproducts is discharged radially from the battery pack venting aperture.A method of venting from a battery pack, comprising: receiving a stream of venting byproducts at a battery pack vent opening; managing thermal energy within the stream of venting byproducts using a coolant that is relayed through the battery pack vent opening; and draining the stream of venting byproducts from the battery pack vent opening.The method of claim 10, further comprising passing the vent byproducts within the battery pack vent between a first ring and a second ring of the battery pack vent, and optionally wherein the coolant is passed through at least one coolant passage within the first ring, within the second ring, or both.The method of claim 11, wherein the first ring and the second ring are coaxially disposed about a vent axis.The method of claim 11, further comprising directing the stream of vent byproducts within the battery pack vent opening radially through at least one first ring opening in the first ring such that the stream of vent byproducts impinges on the second ring and then flows between the first ring and the second ring, and optionally further comprising directing the stream of vent byproducts radially through at least one second ring opening in the second ring.The method of claim 10, further comprising radially draining the bleed byproducts from the battery pack bleed orifice.The method of claim 10, further comprising axially draining the bleed byproducts from the battery pack bleed orifice through an annular outlet.

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