EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust purification device for an internal combustion engine purifies nitrogen oxide contained in exhaust gas by injecting urea water from an injection valve (14) upstream of a catalyst (4) provided in an exhaust passage (2). The exhaust purification device is also provided with a heater (20) for heating the urea water supplied to the injection valve (14). The exhaust purification device is also provided with a pump (13) for varying the pressure of the urea water injected from the injection valve (14) by varying the pressure of the urea water supplied to the injection valve (14). An electronic control unit (30) heats the urea water by means of the heater (20) when the urea water is being injected from the injection valve (14), and increases the pressure of the urea water being injected from the injection valve (14) by means of the pump (13) when the urea water is at a high temperature compared with when said urea water is at a low temperature.