KR101013964B1 - Regeneration system for emission reduce line of diesel vehicle and method thereof - Google Patents

Abstract

When regenerating NOx stored in LNT (Lean NOx Trap) installed as a post-treatment system in a diesel vehicle, the duty cycle of the air volume regulator and fuel injection amount are corrected according to the state of charge (SOC) of the battery. A post-treatment system regeneration device and method for diesel vehicles ensuring stability in regeneration.

The present invention is a process for determining whether the NOx purification efficiency of the LNT is DeNOx regeneration time, if the DeNOx regeneration time of the LNT calculates the required power generation according to the state of charge of the battery and then adjusts the air volume by applying a correction map, alternator according to the air volume adjustment If the amount of generated power is less than the required amount of power generation includes the step of controlling the engine output by correcting the fuel injection amount by the deviation of the power generation amount.

Post-Processing Unit, LNT, State of Charge, Alternator, DeNOx Playback, Map Calibration

Description

Reprocessing system and method of diesel vehicle aftertreatment system {REGENERATION SYSTEM FOR EMISSION REDUCE LINE OF DIESEL VEHICLE AND METHOD THEREOF}

The present invention is to compensate the duty of the air volume control device and the fuel injection amount according to the state of charge (SOC) of the battery when regenerating NOx stored in the LNT (Lean NOx Trap) installed as a post-processing system in a diesel vehicle The present invention relates to a post-processing system regeneration device and method for a diesel vehicle that ensures stability in regeneration of LNT.

In general, the exhaust gas emitted from the engine is guided to a catalytic converter disposed in the middle of the exhaust pipe, purified, passed through a muffler, noise is attenuated, and discharged to the atmosphere through the tail exhaust pipe.

In the OBD regulation, not only the regulation of emission regulations, which is strengthened day by day, but also the improvement and improvement of the diagnostic ability to detect the failure and deterioration of exhaust components, and the standardization in the after service market It is required to satisfy several regulations.

NOx and PM are the main targets of exhaust gas regulation applied to diesel vehicles.

Since NOx is strongly dependent on the temperature of the combustion gases, high concentrations of NOx are produced in the high temperature range.

Therefore, in order to reduce NOx, the reduction of the combustion temperature by the EGR control is effective, but such a method may cause the oxidation efficiency of PM to deteriorate and thermal degradation.

For this reason, the problem of diesel engines is to simultaneously reduce NOx and PM while maintaining high thermal efficiency.

In order to satisfy NOx and PM regulations among North American diesel Tier 2 BIN5 regulations or Euro 6 emission regulations, separate after-treatment systems are applied. DeNOx catalysts such as Diesel Particulate Filter) are applied.

The LNT is composed of a NOx storage catalyst and a DOC (Diesel Oxidation Catalyst) on one carrier, and is installed on the uppermost side of the aftertreatment system close to the engine, and a DPF is installed on the downstream side of the LNT to collect particulate matter (PM). do.

The LNT adsorbs and stores NOx in an oxide catalyst such as platinum (Pt) and a catalyst coat such as barium oxide in a lean driving region, and uses diesel fuel as a reducing agent in a rich operating region. To reduce the NOx stored in the catalyst to regenerate the catalyst.

The NOx purification efficiency of the LNT is approximately 70 to 90% or more, and the activation temperature is approximately 200 ° C to 500 ° C, and the purification of NOx is very good because of the correlation with the temperature range of the load of the diesel engine and the exhaust gas. High efficiency appears.

When the occlusion amount of the NOx increases in the LNT and the purification efficiency of the LNT decreases, the engine control means controls the engine to the rich operating region to regenerate the LNT to remove the occlusion NOx and SOx.

As the performance of the battery and alternator decreases as the vehicle ages, the battery cannot be charged with a normal voltage, and the alternator also fails to generate sufficient voltage.

As described above, when the voltage of the battery and the alternator is not stabilized, normal operation of various actuators including an ACV (Air Control Valve), a T / C (Turbo Charger), an EGR valve, etc., which controls air volume in the engine control is not provided. .

For example, ACV, powered by a battery, operates at a voltage of 9V, T / C at a voltage of 10.8V, and an EGR valve at a voltage of 10V.

Therefore, when the state of charge of the battery is not sufficient, the operation lift (Lift) failure of the ACV, T / C, EGR valve, etc., orbital amount decrease and response time delay occurs.

In addition, the injector for injecting the fuel amount calculated in accordance with the current operating conditions to the combustion chamber is operated by the control voltage applied from the engine control means, the control voltage supplied to the injector due to the aging of the battery and alternator is less than 10V operating voltage In this case, the injector may not be sufficiently operated, resulting in a decrease in fuel injection amount.

As described above, when the battery charge voltage and the alternator voltage generation are not normal, the following problem occurs in the DeNOx regeneration of the LNT.

Due to the delay of the operation of the various actuators for adjusting the air volume, the deNOx regeneration entry time of the LNT is exceeded, and there is a problem that excessive torque fluctuation occurs due to forced switching of the fuel injection amount.

In addition, since the air-fuel ratio is less than the target value when the fuel injection amount is controlled to decrease, it is impossible to supply sufficient reducing agent to the LNT. Therefore, DeNOx regeneration of the LNT is performed while the reducing agent is insufficient, thereby reducing the regeneration efficiency. There is a problem in that the endurance life of the DeNOx regeneration cycle is shortened.

In addition, a stable air-fuel ratio is not secured at the time of DeNOx regeneration of the LNT, thereby deteriorating the emission, and the air volume adjusting actuator and the injector are operated at a low voltage, thereby deteriorating the endurance life.

The present invention has been invented to solve the above problems, the object of which is to monitor the state of charge of the battery and the amount of alternator generated by analyzing the operating voltage of the air volume adjustment actuator and injector operating in the regeneration of LNT, In case of normal operation, the correction map is applied and the fuel injection amount is corrected to provide stabilization of the DeNOx regeneration of the LNT.

A feature of the present invention for achieving the above object is a diesel vehicle comprising a plurality of actuators for adjusting the air volume and the NOx sensor installed at both ends of the LNT and the NOx occluded in the exhaust gas,

Determining the DeNOx regeneration time of the LNT by analyzing the NOx purification efficiency of the LNT and comparing the battery voltage and the reference voltage when the DeNOx regeneration is performed. It provides a post-processing system regeneration device for a diesel vehicle further comprising.

In addition, a feature of the present invention, the process of determining whether the NOx purification efficiency of the LNT regeneration time DeNOx; Calculating the power generation requirement according to the state of charge of the battery at the time of DeNOx reproduction of the LNT, and then adjusting the air amount by applying a correction map; If the power generation amount of the alternator according to the air amount adjustment is less than the required power generation amount includes the step of controlling the engine output by correcting the fuel injection amount by the deviation of the power generation amount.

According to the above-described configuration, the present invention is expected to provide stability to DeNOx regeneration of LNT by correcting the amount of generation, even if a voltage decrease occurs due to aging of the battery and the alternator, so that the effects of torque stabilization and emission stabilization are expected.

In addition, the effect of maintaining the LNT DeNOx regeneration cycle in a stable manner to maintain the endurance life of the LNT and improve fuel efficiency is expected.

In addition, the abnormal operation of the air amount adjusting actuator and the fuel injection amount adjusting device is prevented, so that the endurance life is extended and the stability of the engine operation is provided.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

Since the present invention can be implemented in various different forms, the present invention is not limited to the exemplary embodiments described herein, and parts not related to the description are omitted in the drawings in order to clearly describe the present invention.

1 is a view showing a configuration of an intake and exhaust system of a diesel vehicle according to an embodiment of the present invention.

The diesel vehicle includes a turbine 32 mounted on an intake manifold with energy of exhaust gas by mounting an impeller 31 of the T / C 30 at a predetermined position of an exhaust manifold for discharging the exhaust gas combusted by the engine 10. Supercharge the intake air to the engine (10).

On the downstream side of the impeller 31, an LNT 50 comprising NOx storage catalyst and DOC in one carrier is provided, and a DPF 60 is provided downstream of the LNT 50.

The LNT 50 absorbs and stores NOx in an oxide catalyst such as platinum (Pt) and a catalyst barrier layer such as barium oxide in a lean driving region of the engine 10, and stores fuel in a rich operating region. It is used as a reducing agent to reduce NOx occluded in the catalyst to DeNOx.

The first NOx sensor 51 is installed on the upstream side of the LNT 50, and the second NOx sensor 52 is installed on the downstream side and connected to the control unit 100.

In addition, a temperature sensor is installed downstream of the LNT 50 and is connected to the control unit 100.

The DPF 60 collects particulate matter (PM) contained in the exhaust gas, and the regeneration of the DPF 60 is determined by differential pressure sensors installed upstream and downstream of the DPF 60, and to control the post injection of fuel. Is played by.

The controller 100 analyzes the signals of the first and second NOx sensors 51 and 52 installed at both ends of the LNT 50 to determine the NOx purification efficiency of the LNT 50 to store the NOx and SOx. The time point is determined, and the temperature of the LNT 50 is determined by the signal of the temperature sensor 53.

Then, the deterioration degree of the catalyst according to the information and the durability of the general operating state is detected.

The controller 100 determines whether DeNOx regeneration is necessary from the NOx purification efficiency of the LNT 50, and detects the state of charge of the battery through a battery management system at the time of DeNOx regeneration, and determines whether or not it is lower than a set reference voltage. Judge.

When the state of charge of the battery is higher than the set reference voltage, the reference map according to the current operating conditions is applied to control the actuator for air regulation and the operation of the injector to adjust the fuel injection amount.

That is, maintain the current engine state.

However, when the state of charge of the battery is less than the set reference voltage, the map value of the actuator for air adjustment is corrected according to the state of the voltage, and at the same time, the power generation requirement of the alternator is calculated to operate the air adjustment actuator to compensate the engine output to compensate for the LNT (50). To control stable DeNOx playback.

In addition, although the engine output is compensated through the operation of the air adjusting actuator, if the power generation amount of the alternator does not follow the power generation demand, the fuel injection amount is corrected to compensate for the engine output so that the lean operation area in the DeNOx regeneration operation of the LNT 50 is compensated. By preventing the transition to stabilize the emission, and improves the regeneration efficiency of the LNT (50).

An operation of controlling the engine output in the DeNOx regeneration operation of the LNT in the diesel vehicle according to the present invention including the above-described function will be described in detail with reference to FIG. 2.

When the diesel vehicle operates, the controller 100 analyzes signals of the first and second NOx sensors 51 and 52 installed at both ends of the LNT 50 to determine the NOx purification efficiency of the LNT 50, and from this, the NOx And the amount of occlusion of SOx and detection.

Then, the temperature of the LNT 50 is detected from the signal of the temperature sensor 53 installed on the downstream side of the LNT 50, and the deterioration degree of the catalyst according to the information and the durability of the general operating state is detected (S110).

Thereafter, the control unit 100 determines whether DeNOx regeneration of the LNT 50 is necessary by combining the NOx purification efficiency of the LNT 50 and the detected information (S120).

If it is determined in step S120 that DeNOx regeneration of the LNT 50 is not required, the process returns to step S110. If DeNOx regeneration is necessary, the battery management system detects the state of charge (SOC) of the battery (S130).

Then, it is determined whether the state of charge (SOC) of the battery is less than the set reference voltage (S140).

In the determination of S140, it is determined whether the state of charge (SOC) of the battery is less than the set first voltage, for example, the operating voltage of the ACV actuator (9V) (S141), and when the first voltage is exceeded, it is basic to the operation control of the ACV actuator. Apply the map (S181).

In addition, in the determination of S140, it is determined whether the state of charge (SOC) of the battery is less than the set second voltage, for example, the operating voltage of the T / C actuator, which is 10.8 V (S142). The basic map is applied to the operation control of the C actuator (S182).

In addition, the determination of S140 determines whether the state of charge (SOC) of the battery is less than a set third voltage, for example, an operating voltage of the EGR valve (10 V) (S143). When the third voltage is exceeded, the operation of the EGR valve is controlled. In step S183, the base map is applied.

As described above, when the state of charge (SOC) of the battery exceeds the set reference voltage, the base map is applied to the ACV and T / C actuators and the EGR valves that perform air volume adjustment in the DeNOx regeneration of the LNT 50. It controls (S190).

However, when the state of charge (SOC) of the battery is less than the set reference voltage in the determination of S140, after calculating the required power generation of the alternator from the state of charge (SOC), the generator requires a voltage generation (S150).

According to the power generation request, the voltage generated by the alternator is detected to determine whether the power generation amount is less than the required amount (S160).

If the power generation amount of the alternator is greater than the power generation requirement in step S160, the process returns to step S130 to detect the battery voltage and then repeats the above-described process.

However, if the alternator power generation is less than the power generation requirement, the map values for the operation of the ACV and T / C actuators and the EGR valves that perform air volume adjustment in DeNOx regeneration of the LNT 50 are corrected (S170), and then the ACV and T / C The operation of the actuator and the EGR valve is controlled (S190).

Since the operating voltages of the ACV actuator, the T / C actuator, and the EGR valve are different in S170, the map values to be corrected are determined differently according to the amount of voltage generated in the alternator.

For example, if the voltage generated in the alternator is less than 9 V, for example, the map value is corrected by the deviation of the voltage over the whole. For example, if the voltage exceeds 10 V, the base map is applied to the ACV actuator and the EGR valve. Only the T / C actuator operated at a voltage of 10.8V corrects the map value by the deviation of the voltage.

As described above, the EGR rate and the air volume are lower than the set reference value in the state of adjusting the air volume by applying the base map or the correction map according to the state of charge (SOC) of the battery and the amount of alternator generated in the DeNOx regeneration of the LNT 50. Determine the recognition (S200).

If the EGR ratio and the air volume exceed the set reference value, it is determined whether the elapsed time of DeNOx regeneration of the LNT 50 exceeds the set reference time (S210).

When the EGR ratio and the air volume are less than the reference value in S200 or the elapsed time of DeNOx reproduction of the LNT 50 in S210 exceeds the reference time, the battery voltage, that is, the state of charge (SOC) is detected again through the battery management system (S220). .

In operation S230, it is determined whether the detected state of charge (SOC) of the battery is a set second voltage, for example, less than 10.8V.

When the state of charge (SOC) of the battery exceeds the set second voltage in the determination of S230, the battery determines that the normal state of charge is maintained and applies the basic map to the control of the fuel injection amount (S290).

However, if the state of charge (SOC) of the battery is less than the set second voltage in the determination of S230, after calculating the required power generation of the alternator, and requests generation of power (S240).

According to the power generation request, it is determined whether the voltage generated by the alternator is less than the required amount (S250). If the power generation amount is more than the required amount, the process returns to the process of S230 and the above-described operation is repeated. The fuel injection amount is corrected to compensate for the output (S260).

Then, the operation of the injector is controlled to inject the fuel amount to which the correction value is applied to the combustion chamber of the engine 10 to securely secure the output torque of the engine (S270).

Therefore, in the DeNOx regeneration operation of the LNT 50, the state of charge of the battery and the amount of power generated by the alternator are kept stable so that the rich operating area is stably secured, and the regeneration efficiency of the LNT 50 is kept stable.

The correction map for adjusting the air volume and the fuel injection amount according to the state of charge of the battery and the amount of power generated by the alternator are set as a map table through repetitive learning in advance.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It is included in the scope of rights.

1 is a view showing the configuration of an intake and exhaust system of a diesel vehicle according to an embodiment of the present invention.

2 is a flowchart illustrating a procedure of regeneration of the aftertreatment system in a diesel vehicle according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: engine 30: T / C

50: LNT 60: DPF

100: control unit

Claims (8)

In a diesel vehicle including an actuator for adjusting air volume and an LNT for occluding NOx contained in exhaust gas, The NOx purification efficiency of the LNT is analyzed to determine the DeNOx regeneration time of the LNT, and when the DeNOx regeneration is performed, the battery voltage and the reference voltage are compared. And a controller configured to secure an engine output and a voltage by correcting an air quantity adjustment and a fuel injection amount map value when the reference voltage is less than the reference voltage. delete The method of claim 1, And the control unit calculates an electric power generation requirement of the alternator when the battery voltage is lower than the reference voltage during the regeneration of the DeNOx of the LNT, and controls the air amount adjusting actuator and the fuel amount injection injector to compensate for the engine output. The method of claim 3, The control unit is a post-treatment system regeneration device of the diesel vehicle is applied to the correction value of the actuator for adjusting the air amount according to the battery voltage and the amount of alternator generated during the regeneration of the LNT. Determining whether the NOx purification efficiency of the LNT is at the time of DeNOx regeneration; Calculating the power generation requirement according to the state of charge of the battery at the time of DeNOx reproduction of the LNT, and then adjusting the air amount by applying a correction map; Controlling the engine output by correcting the fuel injection amount by a deviation of the generation amount if the alternator generation amount according to the air amount adjustment is less than the required generation amount; After treatment system regeneration method of a diesel vehicle comprising a. The method of claim 5, The DeNOx regeneration time point of the LNT is determined by applying conditions of NOx and SOx occlusion amount, LNT temperature, driving state, and deterioration degree of LNT. The method of claim 5, The method of regenerating the after-treatment system of a diesel vehicle maintaining the current driving conditions by applying a basic map to the air volume adjustment when the state of charge of the LNT exceeds the reference voltage during regeneration of the LNT. The method of claim 5, The fuel amount correction method of the after-treatment system of a diesel vehicle is applied under a condition that the state of charge of the battery is less than the reference voltage even after the DeNOx regeneration time by adjusting the air volume has elapsed.

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