Abstract: In order to purify NOx in exhaust gas discharged from an engine, a urea water supply system is configured by a urea water injection valve, a urea water tank, urea water supply piping (22) and a urea water supply device (30). Cooling water piping (40) that allows cooling water of the engine to flow through is laid along the urea water supply piping (22), while the cooling water piping (40) is connected to the urea water supply device (30) at a connection portion (34) of an inflow pipe and a connection portion (35) of an outflow pipe, and a part (46) of the inflow pipe is installed to be close to connection portions (31, 32, 33) of the urea water supply piping (22) to the urea water supply device (30) within a predetermined distance range in which heat of the cooling water reaches the connection portions.

Abstract: A tank bracket (23) is formed by a bottom surface part (24) having a first frame body (24A), a second frame body (24B), a third frame body (24C), and a fourth frame body (24D), a first side surface part (25) supported by the first frame body (24A) of the bottom surface part (24) and provided in a vertical direction, and a second side surface part (26) supported by the second frame body (24B) and provided in the vertical direction, and a female screw hole (24E) is provided in the bottom surface part (24). A fixing band (28) for fixing a reduction agent tank (22) is provided on the tank bracket (23). On this, the tank bracket (23) is fixed to an undercover (14) of a revolving frame (5) by using each of the female screw holes (24E) of the bottom surface part (24) in a state in which the reduction agent tank (22) is sandwiched between the second side surface part (26) and a right side frame (11) of the revolving frame (5).

Abstract: In order to purify NOx in exhaust gas discharged from an engine, a urea water supply system is configured by a urea water injection valve, a urea water tank, urea water supply piping (22) and a urea water supply device (30), Cooling water piping (40) that allows cooling water of the engine to flow through is laid along the urea water supply piping (22), while the cooling water piping (40) is connected to the urea water supply device (30) at a connection portion (34) of an inflow pipe and a connection portion (35) of an outflow pipe, and a part (46) of the inflow pipe is installed to be close to connection portions (31, 32, 33) of the urea water supply piping (22) to the urea water supply device (30) within a predetermined distance range in which heat of the cooling water reaches the connection portions.

Abstract: A tank bracket (23) is formed by a bottom surface part (24) having a first frame body (24A), a second frame body (24B), a third frame body (24C), and a fourth frame body (24D), a first side surface part (25) supported by the first frame body (24A) of the bottom surface part (24) and provided in a vertical direction, and a second side surface part (26) supported by the second frame body (24B) and provided in the vertical direction, and a female screw hole (24E) is provided in the bottom surface part (24). A fixing band (28) for fixing a reduction agent tank (22) is provided on the tank bracket (23). On this, the tank bracket (23) is fixed to an undercover (14) of a revolving frame (5) by using each of the female screw holes (24E) of the bottom surface part (24) in a state in which the reduction agent tank (22) is sandwiched between the second side surface part (26) and a right side frame (11) of the revolving frame (5).

Abstract: In a NOx selective catalytic reduction device that purifies NOx in exhaust gas exhausted from an engine, a urea water supply system is constructed of a urea water injection valve, a urea water tank, urea water supply piping and a urea water supply device, a connection frame member is provided on a revolving superstructure to extend in a longitudinal direction in a center in a width direction to reinforce the revolving superstructure and to be located between a pair of main frame members that connects a working device so that a rear side faces the engine, the urea water tank is placed on the revolving superstructure on a front side from a center of revolution of the revolving superstructure, the engine is placed on the revolving superstructure on a rear side from the center of revolution of the revolving superstructure, and the urea water supply device is installed on the connection frame member to face the engine.