Patent ID: 9597637
Date: 2017-03-21
CPC Classifications: B01D,F01N,F02B,Y02T

Claim:
1. An exhaust gas post-processing apparatus for an engine of construction equipment, which removes nitrogen oxide (NOx) by supplying urea in an aqueous solution to an exhaust gas line, the exhaust gas post-processing apparatus comprising: an exhaust pipe which is configured to connect with an exhaust manifold of the engine so as to discharge exhaust gas discharged from the engine; a diesel oxidation catalyst which is in the exhaust pipe and configured to purify the exhaust gas; a selective catalytic reduction which is downstream of the diesel oxidation catalyst, and configured to perform a catalytic reduction reaction so as to reduce nitrogen oxide (NOx) by supplying urea in an aqueous solution form to the exhaust gas, in the exhaust pipe, that has passed through the diesel oxidation catalyst; a first bypass pipe which branches off from the exhaust pipe between the engine and the diesel oxidation catalyst so as to bypass the entirety or a part of the exhaust gas to upstream of the selective catalytic reduction; and a first switch which is at a point where the first bypass pipe branches off from the exhaust pipe, and when a temperature of the exhaust gas is lower than a first predetermined temperature, a temperature of the selective catalytic reduction is lower than a second predetermined temperature, or a temperature inside the engine is lower than a third predetermined temperature, the first switch is configured to adjust an amount of exhaust gas that is bypassed to the first bypass pipe, wherein the first switch is opened so that the exhaust gas is bypassed from the exhaust pipe when the temperature of the exhaust gas or the selective catalytic reduction is within a predetermined first temperature region, wherein the first switch is closed when temperature of the exhaust gas or the selective catalytic reduction reaches a predetermined second temperature region, and wherein the second temperature region is higher than the first temperature region.