Inner case of battery module assembly for vehicle's battery pack

1. A battery pack comprising:

a battery module assembly comprising four battery modules, each module having a plurality of cylindrical secondary battery cells (hereinafter, also referred to as ‘cells’), are electrically connected in series, and a bus bar directly connected to a first side surface of the battery module assembly; and

an inner case, comprising:

a side frame directly contacting two facing sides, other than said first side surface, among sides of the battery module assembly and comprising side frame apertures;

an upper frame comprising a bottom surface configured to directly contact and completely encompass an upper surface of the battery module assembly and the upper frame is directly connected to the side frame, wherein the side frame extends downward from the upper frame; and

an electrode post assembly that comprises two electrode posts, each electrode post having a metal plate, wherein each metal plate is electrically connected to and directly contacts the bus bar at the first side surface and the metal plate directly contacts a top surface of the upper frame, wherein the top surface of the upper frame is opposite to the bottom surface of the upper frame,

wherein the side frame extends from the upper frame to a bottom surface of the battery module assembly,

wherein the side frame is fixedly connected to threaded holes formed at said two facing sides the battery module assembly via screws extending through each of said side frame apertures,

wherein the electrode post assembly is electrically connected to an electrode of the battery module assembly via said bus bar,

wherein the upper frame and the side frame are comprised of a polymer material,

wherein the inner case is configured to be disposed within a lower case and an upper case,

wherein the top surface of the upper frame includes at least one enclosed handle and a space configured to mount a battery management unit thereon, and

wherein the inner case forms a u-shape and is open at an end opposite to the upper frame.

2. The inner case of a battery module assembly according to claim 1 ,

wherein the side frame has at least one hole, other than the side frame apertures, for dissipating heat of the cells.

3. The inner case of a battery module assembly according to claim 1 , wherein the polymer material is polycarbonate.

4. The inner case of a battery module assembly according to claim 1 , wherein the polymer material is an acrylonitrile-butadiene-styrene resin.

5. The inner case of a battery module assembly according to claim 1 , wherein the polymer material is a mixture of polycarbonate (PC) and acrylonitrile-butadiene-styrene resin (ABS), which does not contain a halogen element.

6. The battery pack of claim 1 , wherein the inner case is attached to the battery modules.

7. The battery pack of claim 1 , further comprising:

an upper pack case disposed over the inner case; and

a lower pack case,

wherein the inner case and the battery module assembly are mounted in the lower pack case, and

wherein the entirety of the inner case and the battery module assembly are encompassed by the upper pack case and the lower pack case.

8. The battery module assembly according to claim 7 , further comprising a battery management module positioned on the space of the upper frame of the inner case.