The present application is a 35 U.S.C. 371 Patent Application of PCT Application No. PCT/CN2018/121080, filed on Dec. 14, 2018, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to the technical field of engines, and in particular to an engine exhaust aftertreatment device and a method thereof.

BACKGROUND

At present, due to the requirements of emissions, an aftertreatment device is required to be installed. Through a supported catalyst inside the aftertreatment device, the emissions are converted. The exhaust treatment process of the aftertreatment device is generally treated successively through DOC-DPF-SCR before emission.

The DOC (Diesel Oxidation Catalyst): also known as oxidation catalytic technology, is a device that converts carbon monoxide (CO) and hydrocarbons (HC) in engine exhaust into harmless water (H2O) and carbon dioxide (CO2). The DOC is mainly coated with precious metals such as platinum and palladium, and the main function of the DOC in emission treatment with Euro VI/China VI regulation is to oxidize nitric oxide (NO) in exhaust gas to nitrogen dioxide (NO2), and accelerates the conversion rate and efficiency of nitrogen oxides (NOx) in a subsequent SCR (selective catalytic reduction), and increases the temperature of fuel injected during the regeneration of an oxidized DPF, so as to prepare for the regeneration of the DPF.

The DPF (Diesel Particulate Filter) relies on alternately blocking an inlet and outlet of a carrier hole of a filter to force airflow through a porous wall to achieve the trapping of particles. Generally speaking, the trapping efficiency is over 90%, effectively reducing the emission of pollutants such as PM2.5 in the exhaust gas. In a case that too much ash is trapped, fuel injection is required for the regeneration of the DPF.

Active regeneration: also known as the injection of diesel fuel in the aftertreatment, is that O2reacts with the diesel fuel in the DOC to increase an internal temperature of the DPF, which burns off carbon particles in the DPF by using high temperature.

Passive regeneration: the carbon particles in the DPF react with NO2, which achieves the purpose of removing the carbon particles inside the DPF. The reaction process is: C+2NO2→CO2+2NO.

Thermal management: refers to the use of some control means to increase the temperature of after exhaust and the exhaust entering an interior of the aftertreatment of the engine.

SCR reaction: refers to spraying a urea solution into SCR, and NH3reacts with NOxin the SCR to reduce the concentration of NOxin the exhaust gas. After the temperature exceeds 200 degrees Celsius, the reaction has a relative high efficiency, and the higher the exhaust temperature with a certain range is, the higher the reaction efficiency is.

Urea injection temperature: refers to the minimum temperature required for urea to be completely hydrolyzed and converted efficiently in the SCR.

HC light-off temperature: refers to the minimum temperature required for the complete conversion of HC in the DOC and the DPF (the temperature is generally around 300 degrees Celsius).

The passive regeneration process, however, requires that the carbon particles inside the DPF be reacted by NO2at a relative high exhaust temperature in the exhaust gas. In operating conditions such as cold start or long time idling of the engine, the temperature of a carrier inside the aftertreatment is relative low, and has a low catalytic activity, the energy of the carrier to convert carbon particles is limited, and the efficiency of the passive regeneration is low. At the same time, if a regeneration request of the DPF is occurred, additional thermal management is required. Since the efficiency of the thermal management is poor, it is easy to cause deterioration of fuel consumption of the engine.

In addition, under operating conditions such as cold start or long time idling of the engine, the engine exhaust temperature is low, the internal carrier temperature of the aftertreatment is low, the catalytic activity is low, and the conversion efficiency of the urea in the SCR is low. If the engine is operated for a long time, it is easy to cause emissions of NOxto be high, too much unreacted urea accumulates in the SCR, and a great risk of crystallization is existed in the SCR, which causes the back pressure of the engine to increase and fuel consumption to deteriorate. At the same time, since the efficiency of the thermal management is poor, it is also easy to cause deterioration of fuel consumption of the engine.

Therefore, an existing engine exhaust aftertreatment system generally suffers from low exhaust treatment efficiency and is prone to exhaust excessive emissions.

In summary, the technical problems sought to be solved by those skilled in the art presently are low exhaust treatment efficiency and exhaust excessive emissions.

SUMMARY

An engine exhaust aftertreatment device and method thereof is provided according to embodiments of the present disclosure, which solves the problem of low exhaust treatment efficiency and exhaust excessive emissions of the engine exhaust aftertreatment device.

In view of this, the engine exhaust aftertreatment device according to the present disclosure includes a first exhaust treatment unit and/or a second exhaust treatment unit; the first exhaust treatment unit includes a first bypass pipeline, a first temperature sensor provided on a first connection pipeline and between a DPF and an SCR, a nitrogen oxygen sensor provided downstream of the SCR, and a first intelligent control valve provided on the first bypass pipeline; one end of the first bypass pipeline is in communication with a turbine front exhaust pipe of a turbocharger, and the other end of the first bypass pipeline is in communication with the first connection pipeline; the first temperature sensor, the nitrogen oxygen sensor and the first intelligent control valve are respectively in communication with an ECU of a vehicle; if an engine is in a normal working state, the first intelligent control valve is in a normally closed state; if the engine is in an operating state, and a temperature detected by the first temperature sensor is lower than a first preset value, or if a nitrogen oxygen emission detected by the nitrogen oxygen sensor exceeds a second preset value, or if the engine is in a cold start, the ECU controls the first intelligent control valve to open; the second exhaust treatment unit includes a second bypass pipeline, a second temperature sensor provided on a second connection pipeline and between a DOC and the DPF, a carbon load detection device provided in the DPF, and a second intelligent control valve provided on the second bypass pipeline; one end of the second bypass pipeline is in communication with the turbine front exhaust pipe, and the other end of the second bypass pipeline is in communication with the second connection pipeline; the second temperature sensor, the carbon load detection device and the second intelligent control valve are respectively in communication with the ECU; if the engine is in a normal working state, the second intelligent control valve is in a normally closed state; if the engine is in an operating state, and a temperature detected by the second temperature sensor is lower than a third preset value, or if a carbon load detected by the carbon load detection device reaches a carbon load required by the regeneration request of the DPF, the ECU controls the second intelligent control valve to open.

Preferably, a first one-way valve is provided on the first bypass pipeline, and the first one-way valve only allows one-way communication from one end connected with the turbine front exhaust pipe to the other end connected with the first connection pipeline.

Preferably, a proportion integration differentiation (PID) closed loop is used to adjust the opening degree of the first intelligent control valve.

Preferably, a urea nozzle is further provided on the first connection pipeline for connecting a urea solution, and an intake temperature detection device is provided at an inlet of the engine.

Preferably, an HC nozzle is further provided on a turbine rear exhaust pipe of the turbocharger.

Preferably, a hydrogen oxygen sensor is further provided on the turbine rear exhaust pipe, and the hydrogen oxygen sensor is located between the HC nozzle and a turbine of the turbocharger.

Preferably, a second one-way valve is further provided on the second bypass pipeline, and the second one-way valve only allows one-way communication from one end connected with the turbine front exhaust pipe to the other end connected with the second connection pipeline.

Preferably, a PID closed loop is used to adjust the opening degree of the second intelligent control valve.

Compared with the introduction of the background technology, in the actual use of the above engine exhaust aftertreatment device, if the first intelligent control valve is included, if the engine is in the normal working state, the first intelligent control valve is in the normally closed state, and the exhaust gas passes through the turbocharger and then enters the DOC; if the temperature detected by the first temperature sensor is lower than the first preset value, or if the nitrogen oxygen emission detected by the nitrogen oxygen sensor exceeds the second preset value, or if the engine is in the cold start, it indicates the internal carrier of the aftertreatment has low temperature and poor catalytic activity. This kind of situation is particularly likely to occur under the conditions that the engine is in the cold start or idling for a long time. At this time, the first intelligent control valve is controlled by the ECU to open, so that the high-temperature exhaust gas of the turbine front exhaust pipe is directly introduced into the SCR through the first bypass pipeline, and the high-temperature exhaust gas of the turbine directly enters the SCR without passing through a supercharger, which increases the temperature of the exhaust gas, and quickly activates catalytic activity, reduces emissions and the risk of excessive unreacted urea accumulation in the SCR and internal crystallization of the SCR, improves the efficiency of active regeneration, the action efficiency of the SCR, and the efficiency of the engine. From another perspective, the SCR reaction does not require additional thermal management, which reduces the energy consumption caused by thermal management, thereby reducing the energy waste caused by thermal management in the aftertreatment, and improving the reaction efficiency of the SCR. Therefore, through the first exhaust treatment unit, the exhaust treatment efficiency of the engine exhaust aftertreatment device may be improved, and the risk of exhaust excessive emission is reduced to a certain extent.

If the second intelligent control valve is included, if the engine is in the normal working state, the second intelligent control valve is in the normally closed state, and the exhaust gas passes through the turbocharger and then enters the DOC; if the temperature detected by the second temperature sensor is lower than the third preset value (generally 250 degrees Celsius), or if the carbon load detected by the carbon load detection device reaches the carbon load required by the regeneration request of the DPF, which indicates the internal carrier of the aftertreatment has low temperature and poor catalytic activity. This kind of situation is particularly likely to occur when the engine is in the cold start or idling for a long time. At this time, the second intelligent control valve is controlled by the ECU to open, so that the high-temperature exhaust gas of the turbine front exhaust pipe is directly introduced into the DPF, and the high-temperature exhaust gas of the turbine directly enters the DPF without passing through a supercharger, which increases the temperature of the exhaust, and quickly activates catalytic activity, reduces emissions, and reduces the cumulative rate of carbon deposits inside the DPF and the frequency of active regeneration of the DPF, and improves the reliability of the aftertreatment. From another perspective, if a regeneration of the DPF is requested, there is no need to perform additional thermal management control, which reduces the energy consumption caused by thermal management, thereby reducing the energy waste caused by thermal management in the aftertreatment, and improving the efficiency of the passive regeneration of the DPF. Therefore, through the second exhaust treatment unit, the exhaust treatment efficiency of the engine exhaust aftertreatment device may be improved, and the risk of exhaust excessive emission is reduced to a certain extent.

In addition, an engine exhaust aftertreatment method is further provided according to the present disclosure, and specifically including the steps: detecting an operating mode and an operating condition information of an engine; if it is detected that the engine is in a normal working state, a first intelligent control valve being in a normally closed state; if it is detected that the engine is in an operating state, and a temperature detected by a first temperature sensor is lower than a first preset value, or if a nitrogen oxygen emission detected by a nitrogen oxygen sensor exceeds a second preset value, or if the engine is in a cold start, an ECU controlling the first intelligent control valve to open; if it is detected that the engine is in a normal working state, a second intelligent control valve is in a normally closed state; if it is detected that the engine is in an operating state, and a temperature detected by a second temperature sensor is lower than a third preset value, or if a carbon load detected by a carbon load detection device reaches a carbon load required by a regeneration request of a DPF, the ECU controlling the second intelligent control valve to open.

Since the above engine exhaust aftertreatment device is used by the above method, and the above engine exhaust aftertreatment device has the above technical effects, so the method using the above engine exhaust aftertreatment device also has corresponding technical effects, which will not be repeated here.

