KR20150071377A - Method for reducing of Particulate Number - Google Patents

Abstract

The present invention relates to a method for reducing PN (Particulate Number) in a vehicle through a formation of a soot cake layer by intentionally increasing PN in an initial period of operating a vehicle. According to the present invention, the method for reducing PN in a vehicle comprises: mileage inputting steps (S110, S210) in which an accumulated mileage (ODO) of a vehicle is inputted; DPF regeneration determining steps (S130, S230) for determining whether a DPF (2) which is installed in the vehicle is regenerated; soot excessive discharge adoption determining steps (S140, S240) for determining whether the accumulated mileage (ODO) is less than PN regulation satisfying mileage (mi); and excessive soot discharging steps (S160, S260) for controlling combustion of an engine such that soot may be excessively generated in the exhaust gas discharged from the engine if the accumulated mileage (ODO) of a vehicle is less than PN regulation satisfying mileage (mi) in the soot excessive discharge adoption determining steps (S140, S240).

Description

[0001] The present invention relates to a PN reduction method for a vehicle,

The present invention relates to a method of reducing a PN of a vehicle to satisfy a PN (Particulate Number) restriction of exhaust emission regulation of a vehicle, and more particularly, to a method of reducing a PN of a vehicle by intentionally increasing a PM To a PN reduction method of a vehicle that reduces PN by forming a soot cake layer that can be filtered.

In the vehicle, harmful substances such as CO, SOx, HC, NOx, and PM (Particulate Matter) are discharged by the combustion of the fuel. Various exhaust gas regulations that regulate the amount of harmful substances emitted from the vehicle are further strengthened .

In recent years, the importance of human hazards of ultrafine particles has been emphasized, and PN regulations have been newly applied in order to limit the weight of PM as well as the quantity of PM, and studies are being made on various exhaust gas abatement technologies to cope with this.

On the other hand, in a vehicle equipped with a diesel engine, there is a method for reducing exhausted PM by depositing a soot using a DPF (Diesel Particulate Filter), and burning the soot deposited after a certain condition It is widely used. However, since the size of the pores of the DPF is much larger than the size of the soot, the soot is discharged through the DPF together with the exhaust gas immediately after the regeneration of the DPF, as shown in Fig. There is a problem that the standard, especially the PN regulatory standard, can not be met.

Here, as a measure for coping with the above-mentioned PN regulation, it is possible to cope with the PN regulation by increasing the catalyst coating amount of the DPF or decreasing the pore size of the DPF itself. However, the above-described countermeasure method raises the cost for manufacturing the DPF and increases the back pressure by the DPF to cause the output drop, thus causing another problem such as deterioration of fuel consumption.

JP 2013-087705A

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problems, and it is an object of the present invention to provide a soot cake layer at the inlet side of the DPF immediately after regeneration of the DPF, , And the soot cake layer serves as a filter, thereby suppressing the emission of particulate matter such as soot and satisfying the PN regulation.

According to another aspect of the present invention, there is provided a method of reducing a PN of a vehicle, the method comprising: a DPF regeneration judging step of judging whether or not DPF installed in the vehicle is regenerated; Determining that the soot excess emission application is determined based on the sum of the cumulative travel distance of the vehicle and the exhaust emission amount of the engine, And an excess sucking step of controlling.

In the excess soot discharging step, the amount of the exhaust gas recirculated is increased to cause excessive formation of the soot.

In the excessive-lot discharging step, after-jetting is added so that excessive soot is generated.

In the excessive sucking step, the amount of post-injection is increased so that excess soot is generated.

In the excess-soot discharging step, the fuel injection timing is delayed to cause excessive generation of the soot.

And the operation of the swirl valve is restricted in the excess-soot discharging step so that the soot is excessively generated.

After the excess lot discharging step is performed, it is judged whether the traveling distance after the regeneration of the DPF, which is the travel distance of the cumulative vehicle from the point at which the DPF is regenerated, reaches the excess lot exhausting end distance set to terminate the excess lot discharging step And an excessive set discharge end determination step is performed.

And the oversaturation discharge end distance is set to an integral multiple of the distance per one cycle of the EUDC mode.

And the excessive discharge end distance is any one selected from 7 km, 14 km, and 21 km.

When the running distance after the regeneration of the DPF is greater than the excess discharge end distance, the excess lot discharging step is terminated.

And a basic engine operation step of controlling the engine in a normal manner when it is determined that the cumulative running distance of the vehicle is not less than the PN regulated satisfactory running distance in the step of determining whether the soot excess emission is applied.

A soot collecting amount input step of inputting the amount of soot collected in the DPF between the driving distance input step and the DPF regeneration judging step; The soot collecting amount judging step further comprises a soot collecting amount judging step of judging whether the soot collection amount input in the soot collecting amount input step reaches the PN regulation satisfactory soot collecting amount when the sum Is smaller than the PN regulation satisfactory soot collecting amount, the excess lot discharging step is performed.

And a basic engine operating step of controlling the engine in a normal manner if it is determined in the soot collecting amount determining step that the amount of collected soot is not smaller than the PN regulated satisfactory soot collecting amount.

According to the method for reducing the PN of a vehicle according to the present invention, the combustion is controlled so as to temporarily increase the PM immediately after the DPF regeneration without changing the hardware of the exhaust device, The soot cake layer is formed at an early stage on the inlet side of the soot cake layer, so that the soot cake layer can suppress the exhaust of the soot and satisfy the PN regulation.

In addition, since it is not necessary to increase the catalyst coating amount of the DPF or reduce the size of the pores of the DPF, it is possible to obtain the effect of reducing the PN by changing the control method using the conventional hardware as it is.

In addition, according to the PN reduction method of the present invention, since the number of suites is increased only under a certain condition, it is easy to develop and apply, and since existing hardware is used as it is, PN can be reduced without increasing the manufacturing cost .

1A is a cross-sectional view showing a state in which a soot passes through a DPF immediately after regeneration of the DPF;
1B is a sectional view showing a state in which a soot cake layer is formed on the inlet side of the DPF so that the soot cake layer filters the exhaust of the soot.
FIG. 2 is a graph showing the soot discharge amount versus the PN regulation according to the amount of soot collected in the DPF. FIG.
FIG. 3 is a graph showing the PN regulation versus suit emissions according to the driving distance of the vehicle. FIG.
4 is a flowchart illustrating a PN reduction method of a vehicle according to an embodiment of the present invention;
5 is a flowchart showing a PN reduction method of a vehicle according to another embodiment of the present invention.

Hereinafter, a method for reducing a PN of a vehicle according to the present invention will be described in detail with reference to the accompanying drawings.

The method for reducing the PN of a vehicle according to the present invention increases the amount of PM emission compared to the basic operation immediately after the DPF regeneration and during a certain distance to satisfy the PN regulation so that the soot cake layer is formed at an early stage, As the mileage increases, the amount of soot emissions decreases sharply, so it is applied below a certain mileage. To this end, as shown in FIG. 4, the method for reducing the PN of a vehicle according to the present invention includes a driving distance input step (S110) for inputting a cumulative driving distance (ODO) of a vehicle, a DPF (2) (S140) for determining whether the cumulative running distance (ODO) is less than the PN regulated satisfactory traveling distance (mi), a DPF regeneration judging step (S130) If the cumulative running distance ODO of the vehicle is smaller than the PN regulated satisfactory running distance mi in the excessive emission application judgment step S140, the combustion of the engine is performed so that the soot is excessively generated in the exhaust gas exhausted from the engine (Step S160).

The driving distance input step (S110) is a step of receiving the cumulative driving distance (ODO) of the vehicle. As shown in FIG. 3, as the running distance of the vehicle increases, the amount of the soot discharged decreases. When it is determined that the traveling distance of the vehicle has reached the traveling distance of less than the reference value of the PN regulation And receives the cumulative running distance (ODO). For example, as shown in Fig. 3, as the traveling distance of the vehicle increases, the emission of the PM material having the size to be regulated by the PN is decreased due to the exhaust of the soot. In FIG. 3, when the cumulative running distance exceeds about 10,000 km, the PN regulated value is satisfied. When the cumulative running distance ODO of the vehicle is lower than the PN regulated value, that is, the PN regulated satisfactory traveling distance mi, The driving distance of the vehicle is input.

The DPF regeneration determination step (S130) is a step for determining whether the DPF is regenerated. Since the particulate matter such as soot collected in the DPF immediately after the regeneration is minimized immediately after the regeneration, the DPF is regenerated so that the PN reduction method of the present invention is performed immediately after the DPF is regenerated so that a soot cake layer having a filtering function is formed. The judgment step S130 is carried out.

As shown in FIG. 1A, in the DPF, the DPF is relatively clean immediately after the DPF is regenerated. When the DPF is relatively clean, the soot flowing into the DPF flows through the DPF together with the exhaust gas to the outside It is discharged and does not satisfy the PN regulation. Therefore, in order to allow the soot to be collected on the inlet side of the DPF artificially so as to increase the amount of discharged soot so that the soot cake layer 3 is formed as shown in Fig. 1B, It is determined whether or not the DPF is established.

The soot excess emission application determination step S140 is performed immediately after the DPF is regenerated in the DPF regeneration determination step S130. In the soot excess emission application determination step S140, the cumulative running distance ODO of the vehicle and the PN Compares the regulated satisfactory travel distance mi to judge whether to increase the exhaust of the soot. That is, in the step S140 of judging whether or not the soot excess emission application is performed, it is determined whether the cumulative driving distance ODO of the vehicle is compared with the PN regulated satisfactory traveling distance mi to perform the excess lot discharging step S160 It is determined whether the basic engine operation step S180 is to be performed.

If the cumulative running distance ODO of the vehicle is larger than the PN regulated satisfactory running distance mi (ODO > mi), the exhaust gas already discharged from the engine satisfies the PN regulation. That is, in the process of regenerating the DPF, ash remaining after combustion of the soot is accumulated in the DPF while remaining after regeneration of the DPF, and the accumulated ash acts as a filter. Therefore, when the cumulative running distance (ODO) of the vehicle increases, the remaining amount of the ash increases, and the residual ash blocks the pores of the DPF to serve as a filter, thereby suppressing the exhaust of the soot and satisfying the PN regulation. On the other hand, since the ash does not sufficiently remain in the DPF until the cumulative running distance (ODO) of the vehicle reaches the PN regulated satisfactory traveling distance (mi), the soot contained in the exhaust gas discharged from the vehicle does not satisfy the PN regulation I can not.

Therefore, in the step S140 of determining the soot excess emission application, the cumulative driving distance ODO of the vehicle is compared with the PN regulation satisfactory traveling distance mi to determine whether the excess lot discharging step S160 is to be performed thereafter, It is determined whether the engine operation step S180 is to be performed.

The excess set exhausting step S160 is performed when the cumulative driving distance ODO of the vehicle is smaller than the PN regulated satisfactory traveling distance mi (ODO < mi) in the soot excess emission application judging step S140 The engine is operated so that the exhaust gas contains the soot excessively as compared with the normal operation. That is, the soot layer is deposited so that the exhaust of the soot is filtered on the inlet side of the relatively clean DPF immediately after being regenerated. In order to deposit the soot on the inlet side of the DPF, the engine is operated so that the PM is excessively discharged as compared with the normal operation of the engine, thereby artificially increasing the PM emission amount so that the soot is deposited on the inlet side of the DPF.

When a soot is deposited on the inlet side of the DPF to form a soot cake layer, the soot cake layer functions as a filter, thereby suppressing the exhaust of the soot, so that the PN regulation can be satisfied.

On the other hand, as a method for controlling the engine to cause excessive formation of soot in the excessive sucking step S160, a method of deteriorating the combustion condition of the engine may be proposed. For example, it is possible to increase the amount of recycled exhaust gas, to add post-injection, to increase the amount of post-injection, to delay the fuel injection timing to limit the mixing of fuel and air, or to restrict the operation of the swirl valve And the like. Either one of the above control schemes may be applied alone, or may be applied in combination of two or more. In addition to the above method, another method of controlling the operation of the engine to increase the PM may also be applied.

In addition, the above-described methods for increasing the amount of PM generated from the engine due to combustion can be stored in the form of a map separately from the case where the engine is normally operated in the ECU or the like.

The excess lot discharge end determination step (S170) measures the accumulated travel distance after the DPF is regenerated, and performs the excess lot discharge step (S160) only by a predetermined distance. That is, the running distance D after regenerating the DPF, which is an accumulation running distance from the point where the DPF is regenerated, is compared with the excess set exhaust ending distance DE predetermined to end the exhausting step S160, If the driving distance D is greater than the excess set discharge end distance DE then the excess lot discharging step S160 is terminated and if not D <DE, the excess lot discharging step S160 is terminated. Is repeatedly performed.

Herein, the excess disposal discharge end distance DE is set to an integral multiple of the distance per cycle of the EUDC (Extra Urban Driving Cycle) mode. Since the distance per one time of the EUDC mode is 7 km, the excess disposal completion distance (DE) can be set to 7 km at 1 time, 14 km at 2 times, 21 km at 3 times, and the like.

In the basic engine operation step S180, when it is determined that the cumulative running distance ODO of the vehicle is not smaller than the PN regulated satisfactory traveling distance mi in the soot excess application determination step S140 (ODO > mi) As being executed, the engine is controlled in a normal manner. That is, the ECU controls the engine using a map in which a normal control method is stored so that the soot is not excessively discharged.

Another embodiment of the PN reduction method according to the present invention will be described.

According to another embodiment of the present invention, as shown in FIG. 5, when the amount of soot collected in the DPF is received, it is determined whether the soot is excessively generated according to the amount of the soot collected in the DPF .

To this end, the present embodiment basically proceeds similar to the above-described embodiment, but a part of the process is added. In other words, a soot collecting amount input step (S220) is performed between the input of the traveling distance (S210) and the DPF regeneration determination step (S230) to receive the amount of soot collected in the DPF, (S240) is performed and then the excess collection step S260 is performed through the soot collection amount determination step S250.

In the soot collecting amount input step (S220), the amount (msoot) of the soot collected in the DPF is inputted. In the DPF, the soot discharged from the engine is accumulated in accordance with the operation of the vehicle. By measuring the amount of the soot, the amount of collected soot is inputted to determine whether a soot cake layer for filtering exhaust of the soot is formed. On the other hand, the amount of msoot of the soot collected in the DPF is preferably measured indirectly through the differential pressure of the DPF. That is, the pressure difference between the inlet side and the outlet side of the DPF increases according to the amount (msoot) of the soot collected in the DPF, and the amount (msoot) of the collected soot through the differential pressure of the DPF is predicted.

The soot collecting amount determining step S250 is a step of determining the soot collecting amount msoot of the soot inputted in the suck collecting amount input step S220, m < / RTI > As shown in FIG. 2, when the set is collected in the DPF by more than a predetermined amount, that is, more than the PN regulation satisfactory soot trapping amount m, msoot <m, the excess lot discharging step S260 is performed, > m), and a basic engine operation step (S280) is performed. In addition, after performing the excess lot discharging step S260, the excessive lot discharging end determination step S270 is performed in which the excess lot discharging step S260 is performed only a preset distance after the DPF is regenerated. If the running distance D after the regeneration is greater than the excess discharge end distance DE, then the excess lot discharging step S260 is terminated, otherwise (D <DE), the excess lot discharging step (S260) is repeatedly performed.

Accordingly, in the present embodiment, the cumulative running distance ODO of the vehicle is input (S210), and a soot trapping amount inputting step S220 is performed in which the amount (msoot) of the soot collected in the DPF is inputted, The amount of collected suits is input to the ECU. If the cumulative running distance ODO of the vehicle and the amount of msoot of the soot collected in the DPF are inputted, it is determined whether the DPF is regenerated or not (S230). If it is determined that the DPF is regenerated, if the cumulative running distance ODO of the vehicle is smaller than the PN regulated satisfactory running distance mi (ODO <mi), then the amount msoot of the sucked up soot in the DPF is PN It is judged whether or not the regulatory satisfactory collection amount m has been reached.

If msoot of the soot collected in the DPF is smaller than msoot (m) (msoot <m), the combustion of the engine is controlled so that the soot is excessively generated in the exhaust gas exhausted from the engine (S260). Otherwise, the engine is controlled by a normal control method (S280).

On the other hand, as described above, the method of causing the soot to be excessively generated is problematic in that the amount of EGR is increased, the post injection is increased, the post injection amount is increased, the fuel injection timing is delayed, , Or a method of limiting the operation of the swirl valve is possible.

As described above, according to the PN reduction method of the present invention, after the DPF is regenerated until the cumulative running distance (ODO) of the vehicle reaches the PN regulated satisfactory traveling distance (mi), excess soot is generated, By forming a soot cake layer which suppresses the discharge of the soot, it is possible to cope with the PN regulation which is one of the exhaust regulations of the soot.

1: Suit 2: DPF
3: soot cake layer
S110 and S210: the travel distance input step
S130, S230: DPF regeneration determination step
S140, S240: Over-soot emission application determination step
S160, S260: Excess lot release step
S170, S270: Excess lot exhaustion judgment step
S180, S280: Basic engine operation phase
S220: Entering the lot size
S250: Determination of soot collection amount

Claims (13)

A driving distance input step of inputting a cumulative driving distance of the vehicle,
A DPF regeneration judging step of judging whether the DPF installed in the vehicle is regenerated,
Determining whether the cumulative running distance is less than the PN regulated satisfactory running distance;
If the cumulative running distance of the vehicle is less than the PN-regulated satisfactory traveling distance in the soot excess emission application judgment step, the excess soot exhausting step of controlling the combustion of the engine so that soot is generated excessively in the exhaust gas exhausted from the engine A method of reducing PN of a vehicle comprising:
The method according to claim 1,
In the excess lot discharging step,
So as to increase the amount of recirculated exhaust gas so as to cause excessive formation of the soot.
The method according to claim 1,
In the excess lot discharging step,
And the post-injection is added so that the soot is excessively generated.
The method according to claim 1,
In the excess lot discharging step,
And the amount of post-injection is increased to cause excessive generation of the soot.
The method according to claim 1,
In the excess lot discharging step,
And the fuel injection timing is delayed to cause excessive generation of the soot.
The method according to claim 1,
In the excess lot discharging step,
And the operation of the swirl valve is restricted to cause excessive formation of the soot.
The method according to claim 1,
After the excess lot discharging step is performed,
And an oversupply discharge end determination step of determining whether or not the travel distance after regeneration of the DPF, which is the cumulative travel distance of the vehicle from the point at which the DPF is regenerated, reaches the excess lot exhaust end distance set to terminate the excess lot discharge step Of the vehicle.
8. The method of claim 7,
Wherein the oversaturation discharge end distance is set to an integer multiple of a distance per cycle of an Extra Urban Driving Cycle (EUDC) mode.
8. The method of claim 7,
Wherein the excess lottery discharge end distance is any one selected from 7 km, 14 km, and 21 km.
8. The method of claim 7,
And if the running distance after the DPF regeneration is greater than the oversaturation discharge end distance, the excess lot discharging step is terminated.
The method according to claim 1,
If it is determined that the cumulative running distance of the vehicle is not less than the PN regulated satisfactory running distance at the soot excess application determination step,
And a basic engine operating step of controlling the engine in a normal manner.
The method according to claim 1,
Between the driving distance input step and the DPF regeneration judging step, a soot trapping amount input step of inputting the amount of soot collected in the DPF,
When the cumulative running distance of the vehicle is less than the PN regulated satisfactory traveling distance in the step of determining whether the soot excess emission is applied, the soot collecting amount determining unit determines whether the collected amount of the soot inputted in the soot collecting amount input step reaches the PN regulated satisfactory soot collecting amount Further comprising a judgment step,
Wherein the excess lot discharging step is carried out when the amount of collected soot is smaller than the PN regulating satisfactory soot collecting amount in the soot collecting amount judging step.
13. The method of claim 12,
If it is determined in the soot collecting amount determining step that the amount of collected soot is not smaller than the PN regulation satisfactory soot collecting amount,
And a basic engine operating step of controlling the engine in a normal manner.

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