Vehicle body side structure

1. A vehicle body side structure comprising:

a side sill stiffener having a side sill stiffener extension section extending upward at an end portion of a side sill;

a wheel arch reinforcement member coupled to an upper end portion of the side sill stiffener extension section;

an inner panel coupled to the wheel arch reinforcement member and configured to form a first closed cross section; and

a bulkhead coupled to the side sill stiffener extension section and the wheel arch reinforcement member and configured to partition the first closed cross section.

2. The vehicle body side structure according to claim 1 , wherein the first closed cross section is coupled so as to be continuous with a second closed cross section of the side sill constituted by the side sill stiffener and the inner panel.

3. The vehicle body side structure according to claim 1 , wherein the bulkhead has:

a first connecting section coupled to the wheel arch reinforcement member and the side sill stiffener extension section;

a second connecting section coupled to the inner panel; and

a wall section configured to connect the first connecting section and the second connecting section and having a bead extending toward the first connecting section and the second connecting section.

4. The vehicle body side structure according to claim 3 , comprising:

a side panel outer member configured to cover the side sill stiffener from a side outward of a vehicle;

a first fastening member provided in the side sill stiffener extension section on a side closer to the side panel outer member; and

a second fastening member fastened to the first fastening member in the first closed cross section through an insertion hole formed in a portion of the inner panel corresponding to the first fastening member.

5. The vehicle body side structure according to claim 4 , comprising a hole closing member configured to close the insertion hole.

6. The vehicle body side structure according to claim 1 , wherein a portion to which the side sill stiffener extension section and the wheel arch reinforcement member are coupled is inclined in a vehicle width direction such that a first distance with respect to the inner panel at one of an outward side or an inward side of the portion to which the side sill stiffener extension section and the wheel arch reinforcement member are coupled in the vehicle width direction is greater than a second distance with respect to the inner panel at the other one of the outward side or the inward side of the portion to which the side sill stiffener extension section and the wheel arch reinforcement member are coupled in the vehicle width direction.

7. The vehicle body side structure according to claim 4 , wherein the wall section is provided below the insertion hole, and

a cavity between the first closed cross section and the wall section is set to be smaller than the second fastening member.

8. The vehicle body side structure according to claim 4 , wherein the wall section is provided below the insertion hole and is provided on the first connecting section at a side in which the first closed cross section has a larger region, and

comprises a foaming agent filled into the first closed cross section from the insertion hole.

9. The vehicle body side structure according to claim 4 , wherein, at a portion in which the side sill stiffener extension section and the wheel arch reinforcement member are coupled,

the first connecting section, the wheel arch reinforcement member and the side sill stiffener extension section are coupled by the first fastening member and the second fastening member in at least two places in the vehicle width direction.