Simple and Efficient Turbulator to Promote the Uniform Heat Exchange Inside the Battery Cooling Channel

Abstract

A cooling system for a battery pack includes a fluid source for providing cooling fluid and a turbulator in which the cooling fluid flows along an average flow direction. The turbulator includes a first support member, a second support member, a third support member, a first plurality of rods positioned between the first support member and the second support member, and a second plurality of rods positioned between the second and the third support members. The first plurality of rods is offset from the second plurality of rods in a direction perpendicular to the average flow direction. Finally, the first plurality of rods and the second plurality of rods disrupt fluid flow from the fluid source into non-laminar flow.

Description

The present invention relates to cooling systems for battery packs and, in particular, to battery packs using turbulent air flow cooling systems.

BACKGROUND OF THE INVENTION

Large capacity rechargeable batteries are currently being investigated for use in electric vehicles. The ultimate feasibility of electric vehicles depends on significantly reducing the associated costs. Reduction in the costs of battery assemblies is particularly important.

Lithium ion batteries are an important type of battery technology. Most battery assemblies, including lithium ion battery assemblies, include a plurality of individual electrochemical cells. Typically, such electrochemical cells include an anode and a cathode. Typically, the anode includes a metal sheet or foil (usually copper metal) over-coated with a graphitic layer. Similarly, the cathode usually includes a metal sheet or foil (usually aluminum metal) over-coated with a lithium-containing layer. Finally, electrochemical cells include an electrolyte which is interposed between the anode and the cathode. Terminals allow the generated electricity to be used in an external circuit. Electrochemical cells produce electricity via an electrochemical reaction.

For high power application, a plurality of battery cells are utilized and assembled into a battery module. Moreover, such battery modules are assembled into battery packs which include a cooling system and related electronics for operating the batteries. The cooling systems typically include a plurality of metallic (e.g., copper and/or aluminum) cooling fins interspersed between the battery cells. It turns out that the assembly of such battery modules is fairly difficult with respect to aligning the cooling fins and the battery cells. Moreover, other prior art cooling systems utilize air coolant that impact a plurality of dimples to increase air flow speed.

Accordingly, there is a need for improved battery pact cooling systems.

SUMMARY OF THE INVENTION

The present invention solves one or more problems of the prior art by providing in at least one embodiment, a cooling system for a battery pack. The cooling system includes a fluid source for providing cooling fluid and a turbulator in which the cooling fluid flows along an average flow direction. The turbulator includes a first support member, a second support member, a third support member, a first plurality of rods positioned between the first support member and the second support member, and a second plurality of rods positioned between the second and the third support members. The first plurality of rods is offset from the second plurality of rods in a direction perpendicular to the average flow direction. Finally, the first plurality of rods and the second plurality of rods disrupt air flow from the fluid source into non-laminar flow. Advantageously, the cooling system and turbulator of the present embodiment, increase air speed and promote the uniform heat balance between the opposite walls in the channel of the turbulator in which cooling fluid flows.

In another embodiment, a battery pack integrating the cooling system set forth above is provided. The battery pack includes a plurality of battery cells and a plurality of turbulators disposed between adjacent battery cells in the plurality of battery cells in which cooling fluid flows along an average flow direction. Each turbulator includes a first support member, a second support member, a third support member, a first plurality of rods positioned between the first support member and the second support member, and a second plurality of rods positioned between the second and the third support members. The first plurality of rods is offset from the second plurality of rods in a direction perpendicular to the average flow direction. Finally, the first plurality of rods and the second plurality of rods disrupt fluid flow from the fluid source into non-laminar flow.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 provides a schematic illustration of a battery pack including a cooling system having a turbulator;

FIG. 2 provides a schematic illustration of a cooling system incorporating a turbulator;

FIG. 3A provides a side view of a turbulator interposed between two battery cells;

FIG. 3B is a cross section of a rod used in the turbulator of FIG. 3A;

FIG. 4 is a perspective view of a turbulator used in the cooling system of FIG. 1; and

FIG. 5 provides a flow simulation of the effects of rods to disrupt the flow through the turbulator of FIGS. 1-4.

DESCRIPTION OF THE INVENTION

Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute the best modes of practicing the invention presently known to the inventors. The Figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the invention and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.

Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.

It is also to be understood that this invention is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way.

It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.

Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this invention pertains.

The term “turbulator” refers to a device that turns laminar flow into non-laminar flow, and in particular, into turbulent flow.

The term “laminar flow” refers to fluid flow (e.g., air flow) occurring in parallel layers without disruption between the layers. Alternatively, “laminar flow” as used herein refers to flow with a Reynolds number less than 1000.

The term “non-laminar flow” refers to fluid flow that is not laminar. Alternatively, “non-laminar flow” as used herein refers to flow with a Reynolds greater than 1000.

The term “turbulant flow” refers to fluid flow with a Reynolds greater than 2000. Alternatively, “turbulant flow” as used herein refers to flow with a Reynolds greater than 3000.

With reference to FIG. 1, a schematic cross section of a cooling system for cooling a battery pack is provided. Battery pack 10 includes a plurality of battery cells 12. Typically, battery pack 10 includes from about 5 to about 25 battery cells. Although the present invention is not limited to any particular type of battery cells, lithium ion battery cells are found to be particularly useful Examples of other types of battery cells that may be utilized include, but are not limited to, nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), and the like. Battery pack 10 also includes turbulators 14 through which a cooling fluid flows in order to cool battery cells 12. Turbulators 14 are positioned between adjacent battery cells of the plurality of battery cells 12 or at the ends of battery pack 10. Battery pack 10 also includes control electronics 16 for providing power to an electronically operated device (not shown).

With reference to FIGS. 1-4, schematic illustrations of a battery pack cooling system integrating the turbulators set forth above are provided. FIG. 2 provides a schematic illustration of a cooling system incorporating a turbulator. FIG. 3A is a side view of a turbulator interposed between two battery cells while FIG. 3B is cross section of a rod used in the turbulator. FIG. 4 is a perspective view of a turbulator used in the cooling system of FIG. 1. Cooling system 20 includes fluid source 22 for providing cooling fluid to turbulator 14. In a refinement, fluid source 22 is an air source such as a fan or blower. The cooling fluid flows with turbulator 14 along an average flow direction d₁ from entrance 24 to exit 26. Turbulator 14 includes first support member 28, second support member 30, and third support member 32. Each of support members 28, 30, 32 have a length d_L. In a refinement, the length d_L is from about 50 to 200 mm. A first plurality of rods 34 are positioned between first support member 28 and second support member 30. A second plurality of rods 36 is positioned between second support member 30 and third support member 32. Typically, the first plurality of rods 34 and the second plurality of rods 36 each independently include from 10 to 30 rods. Although, the support members and rods can be formed from any suitable material, plastics and polymeric resins are found to be particularly useful. Examples of such polyolefins include, but are not limited to, (e.g., polyethylene, polypropylene), polystyrene, polyvinyl chloride, polytetrafluoroethylene, and the like. In a refinement, first plurality of rods 34 and second plurality of rods 36 are substantially parallel. The first plurality of rods 34 is offset by a distance d₁ from the second plurality of rods 36 in a direction perpendicular to the average flow direction f₁ from the input flow f, to the output flow f₀ through channels 37 formed in the turbulator. Distance d₁ is measured from the centers of the rods. In a refinement, distance d₁ is from about 2 mm to about 10 mm. Characteristically, the first plurality of rods 34 and the second plurality of rods 36 disrupt air flow from fluid source 22 into non-laminar flow. In a refinement, the first plurality of rods 34 and the second plurality of rods 36 disrupt fluid flow from fluid source 22 into turbulent flow. Turbulator 14 is depicted in FIG. 3 as being positioned between battery cell 12¹ and battery cell 12² such that the first plurality of rods 34 are proximate to battery cell 12¹ and the second plurality of rods 36 is proximate to battery cell 12². Although the present embodiment is not limited by the cross sectional shape of the rods, typically, the cross section has a flat side 38 which is positioned proximate to a battery cell and a rounded side 40 that is more distant from the battery cell.

Still referring to FIGS. 2-4, turbulator 14 further includes fourth support member 44 and fifth support member 46. Third plurality of rods 48 is positioned between third support member 32 and fourth support member 44. Fourth plurality of rods 50 is positioned between the fourth support member 44 and fifth support member 46. As set forth above, second plurality of rods 36 is offset from third plurality of rods 48 and third plurality of rods 48 is offset from the fourth plurality of rods 50. Indeed, in a refinement each plurality of rods is offset from an adjacent plurality of rods by distance d₁. Third plurality of rods 48 is proximate to the first battery cell 12¹ and the fourth plurality of rods is proximate to the second battery cell 12². In a refinement, the distance d_w between the battery cells is from about 2 mm to about 6 mm and the height d_h of turbulator 14 is from about 50 mm to 150 mm.

With reference to FIG. 2, turbulator 14 further includes addition support members and additional rods. For example, as depicted in FIG. 2, turbulator 14 includes support members, 52, 54, 56 with pluralities of rods 58, 60, 62 respectfully interposed as set forth above. The details regarding these additional support members and support rods are the same as those set forth above.

Finally, FIG. 5 provides a flow simulation of the effects of rods to disrupt the flow through the turbulator of FIGS. 1-4. Advantageously, the simulation shows the flow deviating away from the rods and becoming turbulent. This deviation allows for a much better heat transfer than purely laminar flow.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, 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 invention.

Claims

1. A cooling system for a battery pack, the cooling system comprising:

a fluid source for providing cooling fluid; and

a turbulator in which the cooling fluid flows along an average flow direction, the turbulator including: a first support member; a second support member; a third support member; a first plurality of rods positioned between the first support member and the second support member; and a second plurality of rods positioned between the second and the third support members, the first plurality of rods being offset from the second plurality of rods in a direction perpendicular to the average flow direction, the first plurality of rods and the second plurality of rods disrupting fluid flow from the fluid source into non-laminar flow.

2. The cooling system of claim 1 wherein the turbulator is positionable between a first battery cell and a second battery cell such that the first plurality of rods is proximate to the first battery cell and the second plurality of rods is proximate to the second battery cell.

3. The cooling system of claim 2 wherein the turbulator further comprises:

a fourth support member,

a fifth support member;

a third plurality of rods positioned between the third support member and the fourth support member; and

a fourth plurality of rods positioned between the fourth support member and the fifth support members, the third plurality of rods being offset from the fourth plurality of rods.

4. The cooling system of claim 3 wherein the third plurality of rods is proximate to the first battery cell and the fourth plurality of rods is proximate to the second battery cell.

5. The cooling system of claim 1 wherein the first support member and the second support member are each substantially rectangular.

6. The cooling system of claim 1 wherein the fluid source is an air source.

7. The cooling system of claim 1 wherein the first plurality of rods and the second plurality of rods disrupt the fluid flow into turbulent flow.

8. The cooling system of claim 1 wherein each rod of the first plurality of rods and the second plurality of rods has a circular cross with a flat side and a curved side.

9. The cooling system of claim 1 wherein the first support member, the second support member, the first plurality of rods, and the second plurality of rods each independently comprise a plastic.

10. The cooling system of claim 1 wherein the first plurality of rods and the second plurality of rods each independently include from 10 to 30 rods.

11. The cooling system of claim 1 wherein the first plurality of rods and the second plurality of rods are substantially parallel.

12. The cooling system of claim 1 further comprising addition support members and additional rods.

13. A battery pack comprising:

a plurality of battery cells; and

a plurality of turbulators disposed between adjacent battery cells in the plurality of battery cells in which cooling fluid flows along an average flow direction, each turbulator including: a first support member; a second support member; a third support member; a first plurality of rods positioned between the first support member and the second support member; and a second plurality of rods positioned between the second and the third support members, the first plurality of rods being offset from the second plurality of rods in a direction perpendicular to the average flow direction, the first plurality of rods and the second plurality of rods disrupting fluid flow into non-laminar flow.

14. The battery pack of claim 13 wherein the turbulator is positionable between a first battery cell and a second battery cell such that the first plurality of rods is proximate to the first battery cell and the second plurality of rods is proximate to the second battery cell.

15. The battery pack of claim 14 wherein the turbulator further comprises:

a fourth support member,

a fifth support member;

a third plurality of rods positioned between the third support member and the fourth support member; and

a fourth plurality of rods positioned between the fourth support member and the fifth support members, the third plurality of rods being offset from the fourth plurality of rods.

16. The battery pack of claim 15 wherein the third plurality of rods is proximate to the first battery cell and the fourth plurality of rods is proximate to the second battery cell.

17. The battery pack of claim 13 wherein the first support member, the second support member, the first plurality of rods, and the second plurality of rods each independently comprise a plastic.

18. The battery pack of claim 13 wherein the first plurality of rods and the second plurality of rods each independently include from 10 to 30 rods.

19. The battery pack of claim 13 wherein the first plurality of rods and the second plurality of rods are substantially parallel.

20. The battery pack of claim 13 wherein the first plurality of rods and the second plurality of rods disrupt the fluid flow into turbulent flow.