Exhaust gas processing device and construction machine

An exhaust gas processing device to be provided in a construction machine having an upper swinging body including a support frame extending both in a vertical direction and a horizontal direction, an engine provided on the support frame, the exhaust gas processing device adapted for processing exhaust gas of the engine, and comprising:

• an exhaust gas processing unit that is mounted on the support frame and positioned above the engine and allows the exhaust gas of the engine to pass through the exhaust gas processing unit to process the exhaust gas;
• a reduction agent tank that is mounted on the support frame and accommodates a reduction agent capable of reducing the exhaust gas;
• a reduction agent supply unit that is attached to the exhaust gas processing unit to supply reduction agent from the reduction agent tank to the exhaust gas processing unit;
• a cooling unit that has a first end portion and a second end portion positioned on an opposite side to the first end portion, the cooling unit allowing cooling water to pass through the cooling unit with the cooling water exchanging heat with the reduction agent supply unit to thereby cool the reduction agent supply unit, the first end portion being on an uppermost side of the cooling unit, the cooling unit including a cooling water passage, the cooling water passage having a first end connected to the first end portion of the cooling unit and having a second end connected to the second end portion of the cooling unit such that the cooling water passage extends straightly from the first end to the second end;
• a cooling water accommodation unit that is mounted on the support frame and has a lower portion positioned below the cooling unit and accommodates cooling water to be supplied to the cooling unit;
• a first connection pipe that connects the first end portion of the cooling unit and the cooling water accommodation unit;
• a second connection pipe that connects the second end portion of the cooling unit and the cooling water accommodation unit;
• a circulating device that is mounted on the support frame and driven by the engine so as to cause the cooling water to circulate through the first connection pipe and the second connection pipe such that the cooling water accommodated in the cooling water accommodation unit flows into the cooling unit through one of the first end portion and the second end portion of the cooling unit and flows out of the cooling unit through the other one of the first end portion and the second end portion of the cooling unit, wherein
• the first connection pipe and the second connection pipe are connected to the lower portion of the cooling water accommodation unit, and
• the first connection pipe includes:
• a connection portion connected to the first end portion of the cooling unit;
• an apex portion positioned on an uppermost side of the first connection pipe and above the cooling unit;
• and
• a supplying portion that is positioned between the connection portion and the apex portion and accommodates a volume of cooling water to be supplied to the cooling unit in place of the cooling water boiled in the cooling unit having been heated by the exhaust gas after the engine is stopped.