KR20160118635A - Method and device for regenerating exhaust filter of diesel engine - Google Patents

Abstract

The present invention relates to a method and a device for regenerating a filter purifying exhaust gas discharged from a diesel engine. According to the present invention, a device for regenerating an exhaust gas filter of a diesel engine, in an exhaust system having a first filter and a second filter, as the device for regenerating an exhaust gas filter of a diesel engine, wherein without injecting fuel, nature regeneration in which an exhaust gas filter is regenerated by exhaust gas and forcible regeneration in which fuel is injected to regenerate the exhaust gas filter are performed, comprises: a fuel injection unit injecting fuel to forcibly regenerate the first filter and the second filter; and a control unit controlling the fuel injection unit to perform the forcible regeneration.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for regenerating an exhaust gas filter of a diesel engine,

The present invention relates to a method of regenerating a filter for purifying exhaust gas discharged from a diesel engine and a regeneration apparatus.

Generally, diesel engines are widely used in construction machinery, industrial vehicles, trucks, buses, and ships because of their high fuel consumption and power output. However, since NOx and particulate matter (PM) contained in the exhaust gas of the diesel engine cause air pollution, regulations on the emission of these substances are increasing recently.

In order to prevent the harmful substances discharged from the diesel engine from being discharged into the atmosphere, a variety of exhaust gas filters are mounted in the exhaust system of the diesel engine. As typical exhaust gas filters, there are a diesel particulate filter (DPF) and a selective catalytic reduction (SCR) device.

DPF has become the most efficient and practical means of reducing particulate matter such as soot discharged from a diesel engine. The DPF is installed in the exhaust line of the diesel vehicle and has a filter structure for physically collecting the soot. Particulate matter such as unburned soot is filtered by the DPF and deposited on the filter channel of the DPF. When the particulate matter accumulates on the filter, pressure drop occurs by the filter, which increases the back pressure by the filter. Therefore, if the particulate matter accumulated on the filter is not removed, the engine performance decreases. Therefore, by removing the particulate matter accumulated in the filter, it is called regeneration.

The selective catalytic reduction device is used to remove nitrogen oxides that cause acid rain and cause photochemical smog, and nitrogen oxides in the nitrogen oxides are reduced to nitrogen gas using a catalyst to remove nitrogen oxides as air pollutants. However, if the selective catalytic reduction reaction is continued for a certain period of time, the alkali metal and alkaline earth metal contained in the exhaust gas or a compound thereof is adsorbed in the catalyst and acts as a catalyst poison, thereby lowering the activity of the catalyst. Further, sulfuric acid such as Na ₂ SO ₄ , CaSO ₄ and NH ₄ HSO ₄ and particulate matter such as ash, fine dust, SiO ₂ and Al ₂ O ₃ are deposited on the catalyst together with the corrosive substance in the selective catalytic reduction unit, To thereby inhibit the deactivation of the catalyst. Accordingly, as the selective catalytic reduction reaction continues, the performance of the catalyst is drastically reduced, making it difficult to remove the smooth nitrogen oxides. Therefore, in order to solve this problem, it is necessary to remove the catalyst poison adsorbed in the catalyst or the accumulated impurities to regenerate the catalyst of the selective catalytic reduction apparatus.

Regeneration of the exhaust gas filter includes a passive regeneration method and an active regeneration method. Natural regeneration is a method in which particulate matter collected in a filter is naturally burned by a high temperature exhaust gas when the exhaust gas temperature is high. However, when the engine rotation speed is not high, such as during idling of the engine or during low load operation, the exhaust gas generally maintains a relatively low temperature. As a result, the particulate matter is not naturally burned by the exhaust gas but is accumulated in the filter. In this case, the particulate matter deposited on the filter is burned by raising the engine rotation speed artificially or raising the temperature of the exhaust gas by directly injecting fuel into the exhaust line, and this method is called forced regeneration.

It is very important to perform forced regeneration at an appropriate time in the exhaust gas filter. This is because the fuel is consumed in the forced regeneration method. Therefore, even if the accumulation amount of the particulate matter is small, if the forced regeneration is performed more frequently than necessary, fuel consumption is increased and the fuel is wasted. On the other hand, if the forced regeneration is not performed even though the particulate matter is excessively deposited, the engine back pressure is increased, which may cause the engine output and the fuel consumption to be lowered, and the filter performance may be deteriorated.

It is known that the fuel consumption is degraded by about 2% to 5% by forced regeneration. However, since the accumulation amount of particulate matter varies depending on engine specifications, operating conditions, and the like, it is difficult to find an optimum forced regeneration point. Therefore, there is a need to set an appropriate forced regeneration point so as not to excessively accumulate particulate matter while preventing waste of fuel.

Particularly, when two or more kinds of filters are used in combination in the exhaust system, if the forced regeneration is separately controlled for each filter, waste of fuel may be worsened. Therefore, a filter regeneration method There is a great need for.

In addition, the emission amount of particulate matter may vary depending on the specifications of the engine, the characteristics of the construction machine on which the engine is mounted, the working conditions, and the like. Therefore, in order to optimize the forced regeneration of the filter, the forced regeneration condition must be performed by many experiments beforehand for each engine and construction machine, and therefore it takes a lot of time and cost to optimize the forced regeneration. Therefore, there is a great need for a filter regeneration method capable of easily optimizing forced regeneration even for engines and construction machines of different specifications without such prior experiments.

KR 10-2009-0012430 A

Disclosure of Invention Technical Problem [8] The present invention provides an exhaust gas filter regeneration method and regeneration apparatus for a diesel engine which can prevent excessive accumulation of particulate matter in an exhaust gas filter while preventing fuel from being wasted .

It is another object of the present invention to provide an exhaust gas filter regenerating method and regenerating apparatus for a diesel engine which can optimize forced regeneration even in an engine and a construction machine having different specifications by a simple method.

According to an aspect of the present invention, there is provided an exhaust system including a first filter and a second filter, wherein an additional fuel is supplied to regenerate the exhaust gas filter by the exhaust gas and regenerate the exhaust gas filter An exhaust gas filter regeneration apparatus for a diesel engine in which forced regeneration is performed, comprising: a fuel injection unit for injecting fuel; And a control unit for controlling the fuel injection unit to perform forced regeneration, wherein the control unit controls the fuel injection unit to perform the natural regeneration performed before the n-th forced regeneration of the first filter and the forced regeneration of the second filter When the sum of the number of execution times is equal to or greater than a first reference number, the forced playback is not performed after the n-th order and the n-th order of the first filter, And the forced regeneration after the m-th order and the m-th order of the second filter when the sum of the number of times of performing the regeneration and the forced regeneration of the first filter is equal to or greater than the second reference number, .

The present invention also relates to an exhaust system including a first filter and a second filter, wherein the exhaust gas filter is regenerated by the exhaust gas and the regeneration is carried out in which additional fuel is injected to regenerate the exhaust gas filter, A method for regenerating an exhaust gas filter for an engine, the method comprising: setting a forced regeneration condition for the first filter and the second filter; Obtaining a time at which natural reproduction is performed by driving the engine for a predetermined time, a time at which forced reproduction is performed for the first filter, and a time at which forced reproduction is performed for the second filter; The sum of the number of times of natural reproduction performed before the n-th forced reproduction of the first filter is performed and the number of forced reproduction of the second filter performed for the performed forced reproduction of the first filter, Determining whether the number is more than a predetermined number; The sum of the number of times of natural reproduction performed before the m-th forced reproduction of the second filter is performed and the number of times of forced reproduction of the first filter performed for the performed forced reproduction of the second filter, Determining whether the number is more than a predetermined number; And when the sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter performed before the n-th forced reproduction of the first filter is equal to or greater than the first reference number, when the sum of the number of times of natural reproduction performed before the m-th forced reproduction of the second filter and the number of times of forced reproduction of the first filter performed is not less than the second reference number, And resetting the forced regeneration condition for the first filter and the second filter so as not to perform the forced regeneration after the m-th order and the m-th order of the second filter. .

At this time, if the sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter performed before the last round forced reproduction of the first filter is less than the first reference number, When the sum of the number of times of performing the natural reproduction before the reproduction is performed and the number of times of performing the forced reproduction of the first filter is less than the second reference number and the natural reproduction is performed by driving the engine for a predetermined time, The time at which the forced playback of the first filter is performed and the time at which the forced playback of the second filter is performed can be obtained.

The forced regeneration condition for the first filter and the second filter may not include the differential pressure control condition.

According to an embodiment of the present invention, when it is judged whether or not the forced regeneration is performed for a certain filter, if the number of forced regeneration for the natural regeneration and other filters is sufficient, forced regeneration is not performed for the corresponding filter, Is prevented.

Further, according to the embodiment of the present invention, the forced regeneration of each exhaust gas filter can be optimized by a simple method.

Further, according to an embodiment of the present invention, the forced regeneration suitable for the working condition currently being performed by the construction machine is set in real time, so that the forced regeneration can be performed optimally to the working condition.

1 is a view schematically showing an example of an exhaust system to which the present invention is applied.
2 is a diagram schematically showing an exhaust gas filter regeneration apparatus of a diesel engine according to an embodiment of the present invention.
3 is a flow chart schematically showing an exhaust gas filter regeneration method of a diesel engine according to an embodiment of the present invention.
4 is a diagram showing an example of selecting a forced reproduction point for the first filter and the second filter.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 1 is a view schematically showing an example of an exhaust system to which the present invention is applied, and FIG. 2 is a diagram schematically showing an exhaust gas filter regenerating apparatus of a diesel engine according to an embodiment of the present invention.

Referring to FIG. 1, the filter regeneration apparatus and the regeneration method according to an embodiment of the present invention can be applied to an exhaust system including at least two kinds of exhaust gas filters 71 and 72. The exhaust system may be provided in a vehicle, where the vehicle may be a construction machine or an industrial vehicle. The exhaust system may include an exhaust line 80, a first filter 71, and a second filter 72. The exhaust line 80 is a passage through which the exhaust gas discharged from the engine is discharged to the outside. The first filter 71 and the second filter 72 may be arranged in series on the exhaust line 80. For example, the first filter 71 may be a diesel particulate filter, and the second filter 72 may be a selective catalytic reduction device. However, the number and types of the exhaust gas filters 71 and 72 are not limited thereto, and various types of filters requiring regeneration may be provided in various numbers.

The exhaust gas filter regenerating method and regenerating apparatus of a diesel engine according to an embodiment of the present invention can regenerate the exhaust gas by passive regeneration in which the exhaust gas filter is regenerated by the high temperature exhaust gas discharged from the engine without additional fuel injection, And to effectively control active regeneration which additionally injects fuel to regenerate the filter. Unlike natural regeneration, forced regeneration consumes additional fuel, so it is desirable that forced regeneration is not performed as much as possible. However, if the exhaust gas filter is not regenerated sufficiently by natural regeneration, forced regeneration is required but forced regeneration is not performed, the performance of the engine and the exhaust gas filter may be deteriorated due to clogging of the exhaust gas filter. Therefore, by performing the forced regeneration selectively in consideration of the number of natural regeneration, it is possible to achieve both the fuel waste and the filter performance deterioration prevention.

Referring to FIG. 2, an exhaust gas filter regeneration apparatus for a diesel engine according to an embodiment of the present invention includes a fuel injection unit 20 for injecting fuel for forced regeneration of exhaust gas filters 71 and 72, A pressure sensor 30 for sensing the differential pressure between the front and rear ends of the filters 71 and 72, a temperature sensor 40 for sensing the temperature of the exhaust gas filters 71 and 72, The vehicle speed sensor 50 and the control unit 60 for controlling the vehicle speed.

The fuel injection unit 20 is for injecting fuel so as to perform forced regeneration to the exhaust gas filters 71 and 72 and can inject fuel according to a control signal of the control unit 60. [

The pressure sensor 30 senses the pressure difference between the front end and the rear end of the exhaust gas filters 71 and 72. The larger the pressure difference detected by the pressure sensor 30 is, The degree of clogging is increased. The pressure sensor 30 includes a first pressure sensor 31 for sensing the differential pressure between the front and rear ends of the first filter 71 and a second pressure sensor 31 for sensing the differential pressure between the front and rear ends of the second filter 72. [ (Not shown). The pressure sensor 30 may be an absolute pressure sensor for measuring the pressure at the front end and the pressure at the rear end of the exhaust gas filters 71 and 72. A differential pressure sensor Lt; / RTI > The differential pressure sensed by the pressure sensor 30 is transmitted to the control unit 60. [ The control unit 60 determines whether the differential pressure sensed by the pressure sensor 30 is greater than the reference differential pressure. If the sensed differential pressure is greater than the reference differential pressure, the controller 60 can immediately perform forced regeneration.

The temperature sensor 40 is for sensing the temperature of the exhaust gas filters 71 and 72. The temperature sensor 40 may include a first temperature sensor 41 for sensing the temperature of the first filter 71 and a second temperature sensor 42 for sensing the temperature of the second filter 72 . The measured value of the temperature sensor 40 is transmitted to the controller 60 and can be used as information for determining whether to perform the natural reproduction.

The vehicle speed sensor 50 is for sensing the running speed of the vehicle on which the engine 10 is mounted. The traveling speed information of the vehicle sensed by the vehicle speed sensor 50 is transmitted to the controller 60 and can be used as information for calculating the traveling distance of the vehicle. The calculated mileage can be used as information for performing forced regeneration.

The control unit 60 controls the operation of the fuel injection unit 20 based on the information on the operating state of the engine transmitted from the engine 10 and the information transmitted from the pressure sensor 30, the temperature sensor 40 and the vehicle speed sensor 50. [ ) Can be controlled to perform forced playback. The control unit 60 may be configured to include an equipment control unit for controlling a work unit or the like of the construction machine or an engine control unit such as an ECU (Electronic Control Unit), but may be configured as a separate control module.

Hereinafter, the exhaust gas filter regeneration method will be described with reference to the configuration of the exhaust gas filter regeneration apparatus described above.

3 is a flow chart schematically showing an exhaust gas filter regeneration method of a diesel engine according to an embodiment of the present invention. 4 is a diagram showing an example of selecting a forced reproduction point for the first filter and the second filter.

A forced regeneration condition for each of the first filter 71 and the second filter 72 may be set in the control unit 60 (S10). Here, the forced regeneration condition may be the operation time of the engine, the travel distance, the fuel injection amount, the pressure difference between the front and rear ends of the filter, and the like. For example, forcible regeneration can be performed whenever the running time, the running distance, and the fuel injection amount of the engine reach the set value. The operation time and the fuel injection amount of the engine can be calculated by the control unit 60 based on the information transmitted from the engine 10. [ The travel distance can be calculated by the controller 60 based on the information transmitted from the vehicle speed sensor 50. [

When the forced regeneration conditions for the first filter 71 and the second filter 72 are set in the control unit 60, the engine 10 is operated for a predetermined time (S20). During the operation of the engine 10, the forced regeneration may be performed in the order in which the conditions are satisfied among the plurality of forced regeneration conditions set in the control unit 60. [ At the same time, natural regeneration can be performed according to the operating state of the engine 10. [ The control unit 60 can determine whether to perform the natural regeneration based on the temperatures of the first filter 71 and the second filter 72, the engine rotation speed, and the engine operation time. The temperatures of the first filter 71 and the second filter 72 can be transmitted from the first temperature sensor 41 and the second temperature sensor 42 to the control unit 60 and the temperatures of the engine rotation speed and the engine operation time May be transmitted from the engine 10 to the control unit 60. [ On the basis of this information, when the temperature of the first filter 71 or the second filter 72 is equal to or higher than the predetermined temperature and the engine rotation speed is equal to or higher than the predetermined speed and the engine operation time is longer than the predetermined time, It can be determined that the reproduction has been performed. Of course, whether natural reproduction is performed may be determined by a method different from the present embodiment.

(A1, a2, ... an) of the first filter 71 is performed while the engine 10 is running for a predetermined time, and the forced regeneration (b1, b2, ...... bm (C1, c2, ..., ci) is performed (S30). The time at which the forced regeneration (a1, a2, ... an) of the first filter 71 is performed and the point at which the forced regeneration (b1, b2, ...... bm) of the second filter 72 is performed and the natural regeneration , c2, ..., ci) is performed has a temporal posterior relationship. At this time, the forced regeneration (a1, a2, ... an) of the first filter 71, the forced regeneration (b1, b2, ...... bm) of the second filter 72 and the natural regeneration (c1, ci may be performed only once during the driving time of the engine 10 or may be performed in a plurality of circuits. In order to distinguish each forced playback (a1, a2, ... an) performed for the first filter 71 a plurality of times with respect to the first filter 71, the first forced playback is a1, the second forced playback is a2, Playback is indicated by an. (B1, b2, ..., bm) of the second filter 72 are similarly represented by b1 for the first forced regeneration, b2 for the second forced regeneration, and bm for the m-th forced regeneration. Natural reproduction (c1, c2, ...... ci) In addition, the first natural reproduction is represented by c1, the second natural reproduction is represented by c2, and the i-th forced reproduction is represented by ci.

At this time, it is preferable that forcible regeneration (a1, a2, ... an, b1, b2, ... bm) in which the execution time is obtained does not include forced regeneration by the differential pressure condition before and after the filter. This is because unnecessary reproduction of the forced regeneration (a1, a2, ... an, b1, b2, ..., bm) of the first filter 71 and the second filter 72 obtained at this step S30 It is possible to omit the forced regeneration point judged to be in the actual operation because the forced regeneration due to the pressure difference between the front and rear ends of the filter can be omitted at this time. It is preferable that the forced regeneration is performed irrespective of the forced regeneration frequency and the natural regeneration frequency for the other filter when the differential pressure control condition is satisfied, that is, when the differential pressure between the upstream and downstream of the one filter is equal to or greater than the reference differential pressure.

The time at which the forced regeneration (a1, a2, ... an) of the first filter 71 is performed, the point at which the forced regeneration (b1, b2, ...... bm) of the second filter 72 is performed, (a1, a2, ..., an, b1, b2) of the first filter 71 and the second filter 72 performed for a predetermined period of time , ..., bm), the forced regeneration suitable for the current exhaust system is selected.

When the forced regeneration is performed on any one of the filters in the exhaust system in which the first filter 71 and the second filter 72 are provided together, it affects other filters, . That is, the forced regeneration for any one filter can be treated as natural regeneration for the other filter. Therefore, the present invention can consider natural reproduction and forced reproduction of another filter as a criterion for distinguishing between forced reproduction to be performed and forced reproduction to be performed among a plurality of forced reproduction conditions for any one of the filters.

For this purpose, for each forced regeneration of the first filter 71 performed during the driving period of the engine 10, the natural regeneration performed before the nth forced regeneration (an) And the number of forced regeneration of the second filter 72 is equal to or greater than a first reference number (S40, S50). That is, the first-time forced regeneration (a1), the second-time forced regeneration (a2) of the first filter 71, ... it is judged whether or not the sum of the number of times of performing natural reproduction and forced reproduction of the second filter 72 performed before the respective forced reproduction is performed for each of the n-th forced reproduction (an) is equal to or greater than the first reference number S50, S70). At this time, the first reference number may be arbitrarily set in consideration of the characteristics of the exhaust system. The first forced regeneration (a1), the second forced regeneration (a2), the second forced regeneration (a2) of the first filter 71, ... This determination is made for each of the n-th urgent regeneration (an), and the natural regeneration performed before the forced regeneration of the last regeneration of the first filter 71 and the forced regeneration of the second filter 72 When the sum of the number of times is less than the first reference number (S60), the engine 10 is operated again to acquire the point at which the forced regeneration of the first filter 71, the forced regeneration of the second filter 72, After that, the above process can be performed again. At this time, when the engine 10 is operated again, the engine 10 can be operated longer than when the previous engine is operated.

For each forced regeneration of the second filter 72 performed during the driving period of the engine 10, the natural regeneration performed before the m-th forced regeneration (bm) of the second filter 72 is performed, It is determined whether the sum of the number of forced regeneration of the first filter 71 is equal to or greater than the second reference number (S40, S70, S80). That is, the first forced regeneration (b1), the second forced regeneration (b2), and the second forced regeneration (b2) of the second filter (72) ... it is determined whether the sum of the number of times of natural reproduction and forced reproduction of the first filter 71 performed before the forced reproduction is performed for each of the m-times forced reproduction bm is equal to or greater than the second reference number. At this time, the second reference number may be arbitrarily set in consideration of the characteristics of the exhaust system. The first forced regeneration (b1), the second forced regeneration (b2), and the second forced regeneration (b2) of the second filter (72) ... This determination is made for each of the m-times forced recovery bm, but the natural reproduction performed before the point at which the forced reproduction of the last rotation of the second filter 72 is performed and the forced reproduction of the first filter 71 If the sum of the number of times is less than the second reference number (S90), the engine 10 is operated again to acquire the point at which the forced regeneration of the first filter 71, the forced regeneration of the second filter 72, After that, the above process can be performed again.

If the sum of the number of times of natural reproduction performed before the n-th forced reproduction (an) of the first filter 71 is performed and the number of forced reproduction of the second filter 72 is equal to or greater than the first reference number, (An, an + 1, ...) of the first filter after the n-th order and n-th order of the first filter can be set so as not to perform the forced regeneration (an, an + 1, ...). If the sum of the number of times of natural reproduction performed before the m-th forced reproduction (bm) of the second filter 72 is performed and the number of times of forced reproduction of the first filter 71 is equal to or greater than the second reference number, (Bm, bm + 1, ......) of the second filter after the m-th order and m-th order of the second filter may be omitted.

Referring to FIG. 4, forcible regeneration (a1, a2, a3, a4) of the first filter 71 four times, force of the second filter 72 twice The first reference number of times is 3, and the second reference number of times is 4, the reproduction (b1, b2) and the natural reproduction (c1, c2, c3) Since the natural regeneration c1 has been performed and the forced regeneration of the second filter 72 has not been performed before the time point when the forced regeneration a1 has been performed, the first forced regeneration a1 The number of times of performing the natural reproduction and the forced reproduction of the second filter 72 is one, which is smaller than the first reference number. Therefore, the second-time forced regeneration (a2) of the first filter 71, which is the next turn, is determined again.

Since the natural regeneration (c1, c2) has been performed before the second forced regeneration (a2) of the first filter 71 has been performed and the forced regeneration of the second filter 72 has not been performed, The sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter 72 performed before the time when the two-times forced reproduction (a2) of the first filter 71 is performed is two times, which is a value smaller than the first reference number . Therefore, it is judged again for the third forced regeneration (a2) of the first filter 71 which is the next turn.

The natural regeneration (c1, c2) and the forced regeneration (b2) of the second filter 72 at one time were performed before the third forced regeneration (a3) of the first filter 71 was performed. Therefore, the sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter 72 performed before the third forced repetition (a3) of the first filter 71 is performed is three times, It is more than the number of times.

Therefore, the first and the second forced regeneration (a1, a2) of the first filter 71 are carried out in the subsequent engine 10 driving, but the forced regeneration (a3) for three times and the forced regeneration a4 May be set not to be performed. The natural regeneration and the forced regeneration for the second filter 72 have not been performed before the first and the second forced regeneration (a1, a2) of the first filter 71 have been performed, , It is possible to prevent the damage and performance deterioration of the first filter 71 by performing the forced regeneration (a1, a2) of the corresponding count. On the other hand, since the natural regeneration and the forced regeneration of the second filter 72 have already been performed a sufficient number of times before the time when the third forced regeneration (a3) of the first filter 71 is performed, the third forced regeneration ) And the forcible regeneration (a4) after the third repetition are not performed, so that unnecessary consumption of the fuel can be prevented.

Before the first forced regeneration (b1) of the second filter 72 is performed, two natural regeneration (c1, c2) and two first filters 71 (A1, a2) were performed. The sum of the number of times of performing the natural reproduction and the forced reproduction of the first filter 71 performed before the first forced reproduction (b1) of the second filter 72 is performed is four, which is equal to or greater than the second reference number Value. Therefore, the first forced regeneration b1 of the second filter 72 and the forced regeneration b2 after the first regeneration can be set not to be performed at the time of the subsequent engine 10 driving.

As described above, the present invention takes into account not only the number of times of natural reproduction but also the number of times of forced reproduction to be performed for another filter when determining whether to perform the forced reproduction for any one of the filters, The fuel consumption due to the forced regeneration can be reduced.

It will be apparent to those skilled in the art that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. . Therefore, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: engine 20: fuel injection unit
31, 32: pressure sensor 41, 42: temperature sensor
50: vehicle speed sensor 60:
71: first filter 72: second filter
80: Exhaust line

Claims (4)

The exhaust system according to any one of claims 1 to 3, wherein the exhaust gas filter is regenerated by the exhaust gas and the forced regeneration is carried out in which additional fuel is injected to regenerate the exhaust gas filter. As a reproducing apparatus,
A fuel injection unit that injects fuel; And
And a control unit for controlling the fuel injection unit such that forced regeneration is performed,
Wherein,
When the sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter before the n-th forced reproduction of the first filter is equal to or greater than the first reference number, The forced reproduction after the round is not performed,
When the sum of the number of times of natural reproduction performed before the m-th forced reproduction of the second filter is performed and the number of forced reproduction of the first filter is equal to or greater than a second reference number, the m- And does not perform the forced regeneration after the exhaust of the exhaust gas. The exhaust system according to any one of claims 1 to 3, wherein the exhaust gas filter is regenerated by the exhaust gas and the forced regeneration is carried out in which additional fuel is injected to regenerate the exhaust gas filter. As a reproducing method,
Setting a forced regeneration condition for the first filter and the second filter;
Obtaining a time at which natural reproduction is performed by driving the engine for a predetermined time, a time at which forced reproduction is performed for the first filter, and a time at which forced reproduction is performed for the second filter;
The sum of the number of times of natural reproduction performed before the n-th forced reproduction of the first filter is performed and the number of forced reproduction of the second filter performed for the performed forced reproduction of the first filter, Determining whether the number is more than a predetermined number;
The sum of the number of times of natural reproduction performed before the m-th forced reproduction of the second filter is performed and the number of times of forced reproduction of the first filter performed for the performed forced reproduction of the second filter, Determining whether the number is more than a predetermined number; And
When the sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter before the n-th forced reproduction of the first filter is equal to or greater than the first reference number, When the sum of the number of times of natural reproduction performed before the m-th forced reproduction of the second filter is performed and the number of forced reproduction of the first filter is equal to or greater than the second reference number, And resetting the forced regeneration condition for the first filter and the second filter so as not to perform the forced regeneration after the m-th order and the m-th order of the second filter. 3. The method of claim 2,
The sum of the number of times of performing the natural reproduction and the forced reproduction of the second filter performed before the last time forced reproduction of the first filter is less than the first reference number or the last repeated forced reproduction of the second filter When the sum of the number of times of natural reproduction performed before the point in time at which the execution is performed and the number of times of forced reproduction of the first filter is less than the second reference number and the natural playback is performed by driving the engine again for a predetermined time, And a time point at which the forced regeneration is performed for the second filter. 3. The method of claim 2,
Wherein the forced regeneration condition for the first filter and the second filter does not include a differential pressure control condition.

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