TRACTION BATTERY PACK THERMAL MANAGEMENT SYSTEM AND METHOD

A thermal management system for a traction battery pack includes a cell stack having a plurality of battery cells, and a thermal exchange device adjacent the at least one cell stack. The thermal exchange device has at least one coolant passageway that communicates a coolant, and a plurality of thermal breaks configured to inhibit thermal energy transfer from a first area of the thermal exchange device to a different, second area of the thermal exchange device.

TECHNICAL FIELD

This disclosure relates generally to a thermal exchange device that includes thermal breaks to help manage thermal energy within a battery pack.

BACKGROUND

Electrified vehicles differ from conventional motor vehicles because electrified vehicles include a drivetrain having one or more electric machines. The electric machines can drive the electrified vehicles instead of, or in addition to, an internal combustion engine. A traction battery pack assembly can power the electric machines. The traction battery pack assembly of an electrified vehicle can include battery cells.

SUMMARY

In some aspects, the techniques described herein relate to a thermal management system for a traction battery pack, including: at least one cell stack having a plurality of battery cells; a thermal exchange device adjacent the at least one cell stack, the thermal exchange device having at least one coolant passageway that communicates a coolant; and a plurality of thermal breaks in the thermal exchange device, the plurality of thermal breaks configured to inhibit thermal energy transfer from a first area of the thermal exchange device to a different, second area of the thermal exchange device.

In some aspects, the techniques described herein relate to a thermal management system, wherein the thermal exchange device includes at least one plate, the plurality of thermal breaks provided at least in part by apertures in the at least one plate.

In some aspects, the techniques described herein relate to a thermal management system, further including a thermally insulative material within the apertures.

In some aspects, the techniques described herein relate to a thermal management system, wherein the apertures extend completely through the thermal exchange device.

In some aspects, the techniques described herein relate to a thermal management system, wherein at least one cell stack includes a plurality of dividers disposed along a cell stack axis with the plurality of battery cells, the dividers separating groups of at least one battery cell along the cell stack axis, the plurality of thermal breaks aligned with the plurality of dividers along the cell stack axis.

In some aspects, the techniques described herein relate to a thermal management system, wherein the plurality of thermal breaks extend longitudinally in a direction that is transverse to the cell stack axis.

In some aspects, the techniques described herein relate to a thermal management system, wherein the at least one coolant passageway circumferentially surrounds each thermal break within the plurality of thermal breaks.

In some aspects, the techniques described herein relate to a thermal management system, wherein the thermal exchange device includes a first plate and a second plate, wherein the first plate and the second plate are spaced a distance from each other in some areas to provide the at least one coolant passageway.

In some aspects, the techniques described herein relate to a thermal management system, wherein the first plate and the second plate are metal or metal alloy.

In some aspects, the techniques described herein relate to a thermal management system, wherein the plurality of thermal breaks include apertures that open to a first side of the thermal exchange device and to an opposite, second side of the thermal exchange device, the first side facing with the at least one cell stack, the second side facing away from the at least one cell stack.

In some aspects, the techniques described herein relate to a thermal management system, wherein the apertures are filled with a thermally insulative material.

In some aspects, the techniques described herein relate to a thermal management system, wherein the at least one cell stack and the thermal exchange device are constituents of a traction battery pack.

In some aspects, the techniques described herein relate to a battery pack thermal management method, including: establishing thermal breaks within a thermal exchange device to inhibiting thermal energy transfer from a first group of battery cells that are aligned with a first area of the thermal exchange device to a second group of battery cells that are aligned with a different, second area of the thermal exchange device, the first and second groups of battery cells within a cell stack.

In some aspects, the techniques described herein relate to a battery pack thermal management method, wherein the thermal breaks are openings in the thermal exchange device.

In some aspects, the techniques described herein relate to a battery pack thermal management method, wherein the openings extend completely through the thermal exchange device.

In some aspects, the techniques described herein relate to a battery pack thermal management method, wherein the openings are filled with a thermally insulative material.

In some aspects, the techniques described herein relate to a battery pack thermal management method, wherein the openings are adjacent respective dividers within the cell stack.

In some aspects, the techniques described herein relate to a battery pack thermal management method, wherein the thermal exchange device communicates a coolant to manage thermal energy within the cell stack.

In some aspects, the techniques described herein relate to a battery pack thermal management method, further including stamping the thermal exchange device to establish the thermal breaks.

DETAILED DESCRIPTION

This disclosure details battery packs having thermal exchange devices that communicate coolant to manage thermal energy. Thermal breaks within the thermal exchange devices can block thermal energy from transferring through certain areas of the thermal exchange devices.

With reference toFIG.1, an electrified vehicle10includes a traction battery pack assembly14, an electric machine18, and wheels22. The traction battery pack assembly14powers an electric machine18, which can convert electrical power to mechanical power to drive the wheels22. The traction battery pack assembly14can be a relatively high-voltage battery.

The traction battery pack assembly14is, in the exemplary embodiment, secured to an underbody26of the electrified vehicle10. The traction battery pack assembly14could be located elsewhere on the electrified vehicle10in other examples.

The electrified vehicle10is an all-electric vehicle. In other examples, the electrified vehicle10is a hybrid electric vehicle, which selectively drives wheels using torque provided by an internal combustion engine instead of, or in addition to, an electric machine. Generally, the electrified vehicle10could be any type of vehicle having a traction battery pack.

With reference now toFIG.2, the traction battery pack assembly14includes an enclosure assembly34housing a plurality of cell stacks46and at least one thermal exchange device50.

In the exemplary embodiment, the enclosure assembly34includes an enclosure cover40and an enclosure tray44. When the enclosure assembly34is assembled, the enclosure cover40is secured to the enclosure tray44.

In this example, four of the cell stacks46are housed within the enclosure assembly34. Other numbers of cell stacks46could be housed within the enclosure assembly34in other examples. That is, the enclosure assembly34could house more than four cell stacks46or fewer than four cells stacks46.

The cell stacks46each include a plurality of individual battery cells54and dividers58disposed along a respective cell stack axis. The battery cells54can be lithium-ion pouch cells. The dividers58can be mica. The dividers58separate groups of the battery cells54from each other along the cell stack axis. In this example, groups of three individual battery cells54are separated from each other by the dividers58. The dividers58can help to inhibit transfer of thermal energy from one of the groups of battery cells54to axially adjacent groups of the battery cells54.

In this example, two thermal exchange devices50are housed within the enclosure assembly34. The thermal exchange devices50are each adjacent to two of the cells stacks46. In particular, two cell stacks46are disposed atop each thermal exchange device50. Other numbers of thermal exchange devices50could be used in other examples.

A coolant can circulate through the thermal exchange devices50to manage thermal energy levels within the cell stacks46. The coolant can be a liquid coolant.

A coolant supply62, a heat exchanger66, and pump70are outside the enclosure assembly34. The pump70can be used to move coolant from the coolant supply62into the enclosure assembly34to the thermal exchange devices50. The coolant can, for example, take on thermal energy to cool the battery arrays46.

The coolant the moves from the thermal exchange devices50to the heat exchanger66. Thermal energy can transfer from the coolant to ambient at the heat exchanger66. The coolant then moves from the heat exchanger66back to the coolant supply.

With reference now toFIGS.3-6, the thermal exchange device50includes a first plate74and a second plate78. Areas of the second plate78are spaced a distance from the first plate74in some others to provide a coolant passageway82through the thermal exchange device50. The first plate74can be secured to the second plate78with welds, for example. The first plate74and the second plate78can be a metal or a metal-alloy.

The coolant enters the coolant passageway82through an inlet86. The coolant exits the coolant passageway82through an outlet88.

The coolant passageway82, in this example, is configured such that segments of the coolant passageway82pass beneath each of the groups of battery cells54. This can facilitate thermal energy transfer between the battery cells54and the coolant.

Notably, the thermal exchange device50includes a plurality of thermal breaks90, which are configured to inhibit thermal energy transfer from a first area A1of the thermal exchange device50to a different, second area A2of the thermal exchange device50. The area A1is the area of the thermal exchange device50aligned with a first group G1of the battery cells54. The area A2is the area of the thermal exchange device50aligned with a second group G2of the battery cells54.

The thermal breaks90inhibit thermal energy transfer from the area A1to the area A2and vice versa. Without the thermal breaks90, thermal energy from the first group G1of the battery cells54may be more likely to transfer to the area A1, to the A2, and then to the second group G2of battery cells54. Transferring thermal energy from one group of battery cells54within the cell stack46to another group of battery cells could lead to a thermal event, which may be undesirable. The thermal breaks90can inhibit such a transfer of thermal energy.

The thermal breaks90, in this example, are in part provided by apertures94in the thermal exchange device50. The example apertures94extend completely through the thermal exchange device50. That is, the apertures94open to a first side98of the thermal exchange device50, which is provided by the first plate74, and open to a second side102of the thermal exchange device50, which is provided by the second plate78. The apertures94could be stamped into the thermal exchange device50.

The first side98faces the cell stacks46, and the second side102faces away from the cells stacks46. In this example, the cell stacks46are vertically above the thermal exchange device50so the first side98faces vertically upward. Vertical, for purposes of this disclosure is with reference to ground and a general orientation of the vehicle10during operation.

Although the example apertures94are through-holes that extend completely through the thermal exchange device50, apertures in other thermal breaks could be blind holes that extend partially through the thermal exchange device50, such as only through the first plate74or only through the second plate78.

The apertures94are longitudinally extending in this example. The apertures94extend longitudinally transverse to the respective cell stack axis. The apertures94are disposed along the cell stack axis such that the apertures94are aligned with the dividers58.

In this example, the apertures94are filled with a thermally insulative material106, which can help to further inhibit a transfer of thermal energy.

Within the cell stack46, the dividers58inhibit thermal energy transfer. Within the thermal exchange device50, the thermal breaks90inhibit thermal energy transfer. The coolant passageway82, in this example, circumferentially surrounds the thermal breaks90. This can help to facilitate thermal energy transferring to the coolant within the coolant passageway82, particularly thermal energy that may build up due to the thermal break90inhibiting thermal energy from transferring between the first area A1and the second area A2through the first plate74and the second plate78.