# US 7,743,605 B2 · Exhaust emission purifying apparatus for engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,743,605 B2 - Document ID: US7743605B2 - Status: Granted - Kind: B2 - Application number: 12/173,783 - Filed: 2008-07-15 - Published: 2008-11-13 - Granted: 2010-06-29 - Earliest claimed: 2006-06-26 - Assignees: Nissan Diesel Motor Co., Ltd. - Inventors: Toshikazu Katou; Hideki Matsunaga - Web page: https://patentgrep.com/patent/US7743605B2 ## CPC - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - F01N 11/00: Monitoring or diagnostic devices for exhaust-gas treatment apparatus - F01N 13/0097: {the purifying devices are arranged in a single housing} - F01N 2550/05: Systems for adding substances into exhaust - F01N 2560/06: the means being a temperature sensor - F01N 2610/02: the substance being ammonia or urea - F01N 2610/1493: Purging the reducing agent out of the conduits or nozzle - F01N 2900/0418: using integration or an accumulated value within an elapsed period - F01N 2900/08: said parameters being related to the engine - F01N 2900/1808: Pressure - Y02T 10/12: Improving ICE efficiencies - Y02T 10/40: Engine management systems - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An exhaust emission purifying apparatus for an engine in which it is determined that a reducing agent supply system is clogged, which is arranged on the downstream of a pump carrying out suction and pumping of a liquid reducing agent out of a reducing agent tank, when a reduction in a pressure of the liquid reducing agent remaining in the downstream of the pump and also in the upstream of a flow control valve by an amount equal to or more than a first predetermined pressure does not occur until a cumulative injection amount obtained by sequentially integrating an injection amount of the liquid reducing agent computed in real time based on engine operating conditions reaches a predetermined amount after the pump has been temporarily stopped. ## Claims ### Claim 1 An exhaust emission purifying apparatus for an engine, comprising: a reduction catalytic converter which is disposed in an engine exhaust system and reductively purifies nitrogen oxides in the exhaust emission; a reducing agent tank which is provided for storing therein a liquid reducing agent; a pump which carries out suction and supply of the liquid reducing agent by pumping out of the reducing agent tank; a flow control valve which controls a flow rate of the liquid reducing agent supplied by pumping of the pump; an injection nozzle which injection-supplies the liquid reducing agent having flown from the flow control valve by which flow rate of the liquid reducing agent is controlled, to the exhaust emission at a position upstream of the reduction catalytic converter; and a control unit incorporating therein a computer, wherein the control unit computes in real time an injection amount of the liquid reducing agent injection-supplied by the injection nozzle based on engine operating conditions and also, determines that a reducing agent supply system arranged on the downstream of the pump brings about clogging, when a reduction in a pressure of the liquid reducing agent remaining in the downstream of the pump and also in the upstream of the flow control valve by an amount equal to or more than a first predetermined pressure does not occur until a cumulative injection amount obtained by sequentially integrating the injection amount computed in real time reaches a predetermined amount after the pump is temporarily stopped. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the control unit carries out determination as to whether or not the reducing agent supply system brings about clogging, at each first predetermined time after an operation of the engine is started. ### Claim 3 (depends on 1) The apparatus according to claim 1, wherein the control unit forcibly opens the flow control valve for a second predetermined time when the control unit has determined that the reducing agent supply system brings about clogging, by temporarily operating the pump thereby increasing the pressure of the liquid reducing agent flowing in the downstream of the pump and also in the upstream of the flow control valve. ### Claim 4 (depends on 3) The apparatus according to claim 3, wherein the control unit forcibly opens the flow control valve for the second predetermined time only when the exhaust temperature is equal to or higher than the predetermined temperature. ### Claim 5 (depends on 3) The apparatus according to claim 3, wherein the control unit determines that the clogging in the reducing agent supply system is mended, when the reduction in the pressure of the liquid reducing agent remaining in the downstream of the pump and also in the upstream of the flow control valve by an amount equal to or more than a second predetermined pressure occurs while the flow control valve is being forcibly opened for the second predetermined time. ### Claim 6 (depends on 5) The apparatus according to claim 5, wherein the control unit repetitively carries out forcible opening of the flow control valve for the second predetermined time in a state where the pump is temporarily operated to increase the pressure of the liquid reducing agent in the downstream of the pump and also in the upstream of the flow control valve, until it is determines that the clogging in the reducing agent supply system is mended. ### Claim 7 (depends on 6) The apparatus according to claim 6, wherein when the control unit carries out forcible opening of the flow control valve for equal to or more than predetermined numbers of repetition in a row, the control unit activates a warning device, which is capable of indicating that the reducing agent supply system is clogged.