KR101251515B1 - Exhaust gas post processing method - Google Patents

Abstract

Exhaust gas after-treatment method according to an embodiment of the present invention, the set operating parameters including the atmospheric pressure, vehicle speed, engine speed, intake temperature, cooling water temperature, gear stage, fuel injection amount, and exhaust gas temperature is discharged from the engine Determining whether it corresponds to a set operating area for monitoring rapid heat up logic (RHU) for rapidly raising the temperature of the exhaust gas passing through the exhaust line; Sensing an on / off signal for performing or stopping the rapid checkup logic; Determining whether an injection signal for performing the rapid check-up logic is activated; Detecting an error of a component for performing the rapid checkup logic; And sensing the temperature of the exhaust gas and performing comparison with a model value while the rapid shock-up logic is performed.

Description

EXHAUST GAS POST PROCESSING METHOD}

The present invention relates to an exhaust gas aftertreatment method for performing rapid heat up (RHU) logic to rapidly increase the temperature of exhaust gas in order to activate a catalyst for reducing harmful substances contained in the exhaust gas.

According to the conventional exhaust gas purifying apparatus, a soot oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) apparatus are mounted on an exhaust pipe in a set order.

The exhaust gas generated in the engine passes through the diesel oxidation catalyst, the diesel particulate filter, and the selective catalytic reduction apparatus sequentially to remove harmful substances contained in the exhaust gas.

That is, the diesel particulate filter captures particulate matter (PM) contained in exhaust gas, the diesel oxidation catalyst oxidizes carbon monoxide and hydrocarbons contained in exhaust gas to carbon dioxide, and the selective catalytic reduction device The nitrogen oxide contained in the exhaust gas is reduced to nitrogen gas.

On the other hand, in order for the nitrogen oxide to react with the reducing agent, the exhaust gas temperature in front of the selective catalytic reduction apparatus must be 200 ° C or higher. However, since the selective catalytic reduction device is mounted at the end of the exhaust pipe, it takes a long time for the exhaust gas temperature in front of the selective catalytic reduction device to be 200 ° C or more.

Therefore, until the temperature of the exhaust gas in front of the selective catalytic reduction apparatus reaches 200 ° C. or more, the nitrogen oxide contained in the exhaust gas is hardly reduced and discharged to the outside.

Meanwhile, in order to rapidly increase the temperature of the catalyst, a rapid heat up (RHU) logic for rapidly increasing the temperature of the exhaust gas is gradually applied, and an operation region for performing such rapid heat up is determined, and You need a way to accurately determine the error.

Accordingly, the present invention provides an exhaust gas post-treatment method having an on borad diagnosis (OBD) function that performs a rapid checkup logic for rapidly raising the temperature of exhaust gas and determines whether its operation is performed without error. To provide.

The exhaust gas post-treatment method according to the present invention includes determining that the exhaust gas post-treatment method is included in an operating region for monitoring a rapid heat up logic (RHU) for rapidly raising a temperature of exhaust gas passing through an exhaust line. Detecting an on / off signal for performing or stopping the rapid checkup logic; determining whether an injection signal for performing the rapid checkup logic is activated; detecting an error of a component for performing the rapid checkup logic Sensing, and sensing the temperature of the exhaust gas while the rapid shock-up logic is performed and comparing it with a model value.

And outputting an error signal when the temperature of the exhaust gas increased by the rapid shock up logic is out of a model value.

Accumulating the error signal, and storing the accumulated value, and activating a malfunction indicator lamp (MIL) when the accumulated value exceeds a set value.

The operating area for performing the rapid shock up logic must satisfy the conditions for entering the rapid shock up logic, and the conditions for entering the rapid shock up logic include atmospheric pressure, vehicle speed, engine speed, intake temperature, and cooling water temperature. , Gear stage, and fuel injection amount.

If the conditions for entering the rapid check-up logic are satisfied, the after injection amount for performing the rapid check-up is determined based on the engine speed and the fuel injection amount, and the fuel injection amount is increased.

In the step of detecting an error of the component, the component is an injector for injecting fuel, and a temperature sensor for sensing the temperature of the exhaust gas.

The exhaust line includes a diesel oxidation catalyst for oxidizing harmful substances in the exhaust gas, a diesel particulate filter for filtering particulate matter contained in the exhaust gas, a dosing module for injecting a reducing agent into the exhaust gas passing through the exhaust line, and the dosing module. Selective catalyst reduction (SCR) units for oxidizing / reducing nitrogen oxides contained in the exhaust gas by using a reducing agent injected from the gas are sequentially disposed.

A temperature sensor for sensing the temperature of the rear end of the engine, the front end of the diesel oxidation catalyst, the front end of the diesel particulate filter, and the front end of the selective catalyst reduction unit.

As described above, in the exhaust gas aftertreatment method according to the present invention, a self-diagnosis for performing rapid check-up logic for rapidly raising the temperature of exhaust gas and determining whether the operation thereof is performed without error (OBD) It is possible to provide an exhaust gas aftertreatment method having a function.

1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.
2 is a schematic flowchart of an exhaust gas post-treatment method according to an embodiment of the present invention.
3 is a flowchart showing in detail an exhaust gas post-treatment method according to an embodiment of the present invention.
4 is a graph showing the temperature of the exhaust gas and its self-diagnosis function in the state where the rapid shock-up logic is performed in the exhaust gas post-treatment method according to the embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.

1, the exhaust gas aftertreatment system includes an engine 100, an injector 110, a controller 120, an exhaust line 130, a diesel oxidation catalyst 140, a diesel particulate filter 150, a dosing module ( 160), mixer 170, selective catalytic reduction unit 180, and temperature sensors (T3, T4, T5, T6, T6, and T7).

The injector 110 is installed in the engine 100, and the injector 110 injects fuel into a cylinder and performs post-injection for a rapid checkup (RHU).

Exhaust gas discharged from the engine 100 may include the diesel oxidation catalyst 140, the diesel particulate filter 150, the mixer 170, and the selective catalyst reduction unit 180 of the exhaust line 130. Passed sequentially and discharged to the outside through a muffler (not shown).

The temperature sensors (T6, T7) are the temperature of the exhaust gas flowing into the diesel oxidation catalyst 140, the temperature of the exhaust gas flowing into the diesel particulate filter 150, and introduced into the selective catalyst reduction unit 180. The temperature of the exhaust gas is detected.

The controller 120 determines whether to perform rapid heat up (RHU) logic by using the operating state of the engine 100 and the temperature of the exhaust gas passing through the exhaust line 130, and prepares the rapid heat up logic. If the condition for performing the above is satisfied, the post-injection is additionally performed along with the normal injection through the injector 110.

In addition, the controller 120 may not stop or start the rapid check-up logic by using the operating state of the engine 100 and the temperature of the exhaust gas passing through the exhaust line 130.

2 is a schematic flowchart of an exhaust gas aftertreatment method according to an embodiment of the present invention, and FIG. 3 is a flowchart showing an exhaust gas aftertreatment method according to an embodiment of the present invention in detail.

Referring to FIG. 2, it is determined whether the RHU function monitoring condition is performed in S200. Here, it is determined whether the area for monitoring the rapid check-up function.

Here, the area to monitor the rapid check-up function may be regarded as a state in which the rapid check-up function is performed.

In more detail, in ① of FIG. 3, the control unit 120 detects atmospheric pressure, vehicle speed, engine speed, intake temperature, cooling water temperature, gear stage, fuel injection amount, and exhaust gas temperature (T6 or T7). In addition, it is determined whether the rapid checkup function is performed, and the state in which the rapid checkup function is performed is continuously monitored.

In S210 of FIG. 2, it is determined whether the rapid check-up function is on or off, and in S220, it is determined whether an injection signal for rapid check-up is activated.

The injection signal includes a driving signal applied by the controller 120 to allow the injector 110 to perform post-injection.

In S230, an error of a component for performing the rapid check-up is determined. Referring to ④ of FIG. 3, the injector 110 and the temperature sensors T3 to T7 are used to perform the rapid check-up, and the injector 110 or the temperature sensors T3 to T7 malfunction. Or if it fails, the control unit 120 generates an error signal of a component for rapid setup.

In S240, while performing the rapid check-up, the temperature of the exhaust gas is sensed and compared with the modeled temperature region to determine whether the temperature of the exhaust gas is included in the set temperature region.

In S250, when the rapid check-up ends, the monitoring operation ends and the result is output. Referring to ⑤ and ⑥ of FIG. 3, the temperature of the exhaust gas is detected by sensing the temperature of the exhaust gas using the temperature sensor.

More specifically, during the monitoring period, if the temperature of the exhaust gas exceeds the set temperature range, an error signal is generated, the generated error signal is counted (cumulative), and the counted number of times is stored.

In addition, if the counted number exceeds the set value, it is determined that the rapid heat up logic (RHU) operates abnormally, thereby activating a malfunction indicator lamp (MIL).

4 is a graph showing the temperature of the exhaust gas and its self-diagnosis function in the state where the rapid shock-up logic is performed in the exhaust gas post-treatment method according to the embodiment of the present invention.

Referring to FIG. 4, the horizontal axis represents time, and the vertical axis represents the temperature of the exhaust gas flowing into the selective catalytic reduction unit 180.

As shown, the range of the RHU model temperature 400 is set by the set map data, and the graph of the exhaust temperature 410 actually flowing into the selective catalyst reduction unit 180 while the RHU is running (ON) is shown. Is formed. In addition, a graph of exhaust temperature 420 is also set while RUH is not performed (OFF).

In addition, the operating conditions of the engine and the temperature (430) of the exhaust gas modeled by the rapid check-up (RHU) logic are also formed, and an error signal at a portion exceeding the modeled temperature (430) and the set temperature range (400). 440 is generated.

The controller 120 counts the error signal, stores the counted number of times, and activates a warning light MIL when the counted number is out of a set value.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

100: engine
110: injector
120: control unit
130: exhaust line
140: diesel oxidation catalyst (DOC)
150: diesel particulate filter (DPF)
160: dosing module
170: mixer
180: selective catalyst reduction (SCR unit)
T3, T4, T5, T6, T7: Temperature Sensor

Claims (8)

The set operating variables, including atmospheric pressure, vehicle speed, engine speed, intake temperature, cooling water temperature, gear stage, fuel injection amount, and exhaust gas temperature, are used to rapidly increase the temperature of the exhaust gas discharged from the engine and passing through the exhaust line. Determining whether it corresponds to a set operating area for monitoring a rapid heat up logic (RHU);
Sensing an on / off signal for performing or stopping the rapid checkup logic;
Determining whether an injection signal for performing the rapid check-up logic is activated;
Detecting an error of a component for performing the rapid checkup logic; And
Sensing the temperature of the exhaust gas while the rapid check-up logic is performed and comparing it with a model value; Exhaust gas after-treatment method comprising a. In claim 1,
Outputting an error signal when the temperature of the exhaust gas raised by the rapid check-up logic is out of a model value; Exhaust gas after-treatment method further comprising. In claim 2,
Accumulating the error signal; And
Storing a cumulative value, and activating a rapid indicator logic signal (MIL) if the accumulated value exceeds a set value; Exhaust gas after-treatment method further comprising. In claim 1,
The operation area for performing the rapid check-up logic must satisfy a condition for entering the rapid check-up logic,
The exhaust gas post-treatment method is characterized in that the conditions for entering the rapid check-up logic are determined based on atmospheric pressure, vehicle speed, engine speed, intake air temperature, cooling water temperature, gear stage, and fuel injection amount. 5. The method of claim 4,
If the conditions for entering the rapid check-up logic are satisfied,
Based on the engine speed and the fuel injection amount, the after-injection amount for performing the rapid check-up is determined, and the fuel injection amount is increased. In claim 1,
In detecting an error of the component,
The component includes an injector for injecting fuel; And exhaust gas after-treatment method that is a temperature sensor for sensing the temperature of the exhaust gas. In claim 1,
The exhaust line
Diesel oxidation catalyst for oxidizing harmful substances contained in the exhaust gas;
Diesel particulate filter for filtering particulate matter contained in the exhaust gas;
A dosing module for injecting a reducing agent into the exhaust gas passing through the exhaust line; And
And a selective catalyst reduction unit (SCR) for sequentially oxidizing / reducing nitrogen oxides contained in the exhaust gas by using a reducing agent injected from the dosing module. In claim 7,
And a temperature sensor detects the temperature of the rear end of the engine, the front end of the diesel oxidation catalyst, the front end of the diesel particulate filter, and the front end of the selective catalyst reduction unit.

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