A battery unit comprises a bypass structure. The bypass structure includes a bypass exit opening formed at one end of a second direction traversing a first direction at a first end of the battery case, the first direction being oriented from the first end to a second end at which an outlet is formed, a bypass entrance opening formed in a central part of the battery case along the first direction and in a central part along the second direction, a bypass duct by which the bypass exit opening communicates with the bypass entrance opening, and a flow path which guides a cooling gas downstream of the bypass entrance opening to both sides of the second direction.
1. A battery unit comprising:
a battery case having an inlet to let in a cooling gas and an outlet to let out the gas;
a plurality of battery modules stored and held in the battery case; and
a bypass structure whereby part of the cooling gas bypasses the battery modules arranged on the side of a first end of the battery case at which the inlet is formed,
the bypass structure including:
a bypass exit opening formed at one end of a second direction traversing a first direction at the first end of the battery case, the first direction being oriented from the first end to a second end at which the outlet is formed;
a bypass entrance opening formed in a central part of the battery case along the first direction and in a central part along the second direction;
a bypass duct by which the bypass exit opening communicates with the bypass entrance opening; and
a flow path which guides the cooling gas downstream of the bypass entrance opening to both sides of the second direction.
2. The battery unit according to claim 1 , wherein the cooling air inlet and the bypass exit opening are arranged at the first end with a greatest possible distance therebetween.
3. The battery unit according to claim 1 , wherein the battery case is mounted on a vehicle body and the second direction is a vehicle width direction,
the inlet is disposed on the side of a seat next to the driver, and
the bypass exit opening is disposed on the side of a driver's seat.
4. The battery unit according to claim 2 , wherein the battery case is mounted on a vehicle body and the second direction is a vehicle width direction,
the inlet is disposed on the side of a seat next to the driver, and
the bypass exit opening is disposed on the side of a driver's seat.
5. The battery unit according to claim 1 , wherein the bypass duct has a concave section open on the side of the battery case and includes a flange which circumferentially expands on the peripheral edge of the bypass duct, and
the flange is in contact with the outer surface of the battery case, and the flange is welded to the battery case on the side of the first end.
6. The battery unit according to claim 5 , wherein at least part of the flange is fixed to the battery case by a bolt and a nut.
7. The battery unit according to claim 6 , wherein a boss which is thinner than the bolt and which pierces the battery case is formed in a portion of the flange corresponding to the first end, and
the boss piercing the battery case is melted so that the flange is welded to the battery case.
8. The battery unit according to claim 1 , wherein the battery case includes:
a tray member on which the battery modules are mounted; and
a cover member covering the tray member,
the inlet being formed in the cover member.