JP2010216327A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and constantly stably perform the regeneration processing of a particulate filter in a simple device configuration. <P>SOLUTION: The exhaust emission control device includes: a regeneration command means 15 for estimating the accumulation amount of particulates in the particulate filter 5 using at least one of a detected differential pressure 13a from a differential pressure detector 13 for detecting the differential pressure between the front and rear of the particulate filter 5 and a state amount 19 of an engine 1, and outputting a regeneration processing command 16 so as to raise the exhaust gas temperature by just a set time when the estimated accumulation amount of the particulates becomes a set value; and a regeneration time extending command means 17 for estimating the remaining accumulation amount of the particulates by performing differential pressure detection by the differential pressure detector 13 in a fixed period after output of the regeneration processing command 16 by the regeneration command means 15 is completed, storing the remaining accumulation amount when the remaining accumulation amount of the particulates is larger than the set value, and commanding to extend the regeneration processing time according to the remaining accumulation amount in the next regeneration processing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device.

  The exhaust gas purification system for diesel engines is equipped with a particulate filter in the exhaust passage that collects and deposits particulates (particulate matter: hereinafter referred to as particles) contained in the exhaust gas. There is something. When particles accumulate and the particulate filter needs to be regenerated, the fuel is added to the exhaust gas, or the post-injection is performed following the main injection of the fuel to the diesel engine. The particulate filter is regenerated by raising the temperature and burning out the accumulated particles. At this time, the particles are not uniformly adhered and deposited on the particulate filter, but many particles are deposited on the front surface (inlet portion) where the exhaust gas is introduced, and thus the particles are deposited on the particulate filter front surface. As a result, the exhaust pressure of the exhaust gas rises and adversely affects the performance of the diesel engine. Therefore, when predetermined particles are deposited on the front surface of the particulate filter, the regeneration process is performed.

  An exhaust aftertreatment device that estimates the amount of particles deposited on the front surface of the particulate filter and performs the regeneration processing of the particulate filter is disclosed in Patent Document 1.

JP 2006-057608 A

  However, the exhaust aftertreatment device disclosed in Patent Document 1 is based on the particle loss accumulated on the particulate filter during the non-regeneration processing of the particulate filter based on the pressure loss of the particulate filter detected by the pressure loss detecting means. First particle accumulation amount estimating means for estimating the amount, and second for estimating the particle accumulation amount accumulated on the particulate filter during the non-regeneration processing of the particulate filter based on parameters other than the pressure loss of the particulate filter. A particle accumulation amount estimating means and means for comparing these two kinds of particle accumulation amounts to determine whether or not the end face of the particulate filter is clogged, and for estimating the particle accumulation amount; The method is very complex, which makes the computation control device complex and expensive, and Applied to the diesel engine, there is a problem that it is difficult.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust emission control device that can easily and always stably perform regeneration processing of a particulate filter with a simple device configuration.

The exhaust emission control device of the present invention includes a particulate filter in the exhaust passage of a diesel engine, and when the particulate filter needs to be regenerated due to the accumulation of particles, the exhaust gas temperature is raised to regenerate the particulate filter. In the exhaust emission control device that performs
Estimating the amount of accumulated particles in the particulate filter using at least one of the detected differential pressure from the differential pressure detecting means for detecting the differential pressure before and after the particulate filter and the state quantity of the engine, and the estimated accumulated amount of particles Regeneration command means for outputting a regeneration processing command so that the exhaust gas temperature is raised for a set time when becomes a set value;
After the output of the regeneration processing command by the regeneration command means is completed, the residual amount of particles is estimated by detecting the differential pressure by the differential pressure detection means for a certain period, and the residual amount of particles is larger than the set value And a regeneration time extension command means for storing the remaining deposition amount and instructing to extend the regeneration processing time in accordance with the remaining deposition amount at the next regeneration processing.

  Thus, in the exhaust emission control device, the regeneration command means exhausts the exhaust gas for a set time based on the amount of accumulated particles estimated using at least one of the detected differential pressure from the differential pressure detecting means and the engine state quantity. Since the temperature is raised, the regeneration process of the particulate filter can be easily performed. Further, the residual accumulation amount of particles is estimated by the regeneration time extension command means by detecting the differential pressure by the differential pressure detection means in a certain period after the regeneration processing command by the regeneration command means is completed, If it is larger than the set value, the remaining accumulation amount is stored, and during the next regeneration process, the regeneration time extension command means commands to extend the regeneration processing time in accordance with the remaining deposition amount. The remaining accumulated particles are burned out.

  According to the exhaust emission control device of the present invention, the regeneration command means exhausts the exhaust gas for a set time based on the amount of accumulated particles estimated using at least one of the detected differential pressure from the differential pressure detecting means and the engine state quantity. Since the temperature is raised, the regeneration process of the particulate filter can be performed simply, and the differential pressure detection means detects the differential pressure in a certain period after the regeneration process command by the regeneration command means is completed. The remaining accumulation amount of the particles is estimated by the regeneration time extension command means, and if the remaining deposition amount is larger than the set value, the remaining deposition amount is stored, and the regeneration time extension instruction means is stored at the next regeneration processing. Command to extend the regeneration time in accordance with the amount of remaining deposits, so that the remaining deposited particles will be burned out during the next regeneration process. It can achieve an excellent effect that the performance of the Tofiruta can always stable recovery.

It is a schematic block diagram which shows an example of the form of the exhaust gas purification apparatus which implements this invention. It is a graph of the estimated deposition value which shows the relationship between the detection differential pressure before and behind the particulate filter calculated | required from experience data, and a particle deposition amount. It is a diagram which shows an example of the regeneration process instruction | command by adding predetermined fuel addition amount only for setting time. It is a diagram which shows the state which adds extension time with respect to setting time at the time of the next reproduction | regeneration. It is a flowchart which shows an example of the control of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of an embodiment of the present invention. In FIG. 1, in the exhaust gas 3 in the middle of the exhaust pipe 4 through which the exhaust gas 3 discharged from the diesel engine 1 through the exhaust manifold 2 flows. 1 shows an exhaust emission control device in which a particulate filter 5 that collects and deposits particles (particulates) contained in is arranged.

  Further, in the exhaust gas purification apparatus of FIG. 1, a fuel addition nozzle 6 is provided upstream of the particulate filter 5, and an addition valve 8 and a fuel tank 7 provided at a required place are provided on the way between the fuel addition nozzle 6 and the fuel tank 7. A fuel addition device 11 connected by a fuel addition line 10 equipped with a supply pump 9 is provided. The fuel addition device 11 drives the supply pump 9 to supply fuel 12 (mainly HC: hydrocarbon) in the fuel tank 7. In addition, a predetermined addition amount is added to the upstream of the particulate filter 5 via the addition valve 8 for a predetermined time.

  As described above, when the fuel 12 is added to the exhaust gas 3 upstream of the particulate filter 5 by the fuel addition device 11, the catalyst bed temperature of the particulate filter 5 rises due to the oxidation reaction of the fuel 12, and deposits on the particulate filter 5. The particulates 5 burned and removed, and the particulate filter 5 is regenerated.

  In the exhaust gas purification apparatus of FIG. 1, a differential pressure detector 13 (differential pressure detection means) for detecting the differential pressure before and after the particulate filter 5 is provided, and the flow rate of the exhaust gas 3 flowing inside the exhaust pipe 4 is set. An exhaust flow rate detector 14 (exhaust flow rate detecting means) for detecting is provided, and a detected differential pressure 13a detected by the differential pressure detector 13 and a detected exhaust flow rate 14a detected by the exhaust flow rate detector 14 are input. The regeneration command controller 15 (regeneration command means) is provided. The regeneration command controller 15 estimates the particle accumulation amount of the particulate filter 5 from the detected differential pressure 13a of the differential pressure detector 13 and the detected exhaust flow rate 14a of the exhaust flow rate detector 14.

  That is, the regeneration command controller 15 is preliminarily input with an estimated deposition value X indicating the relationship between the detected differential pressure before and after the particulate filter 5 shown in FIG. In FIG. 2, the detected differential pressure when the particles are not deposited on the particulate filter 5 (initial) shows the initial value a0, and from this state, the amount of accumulated particles gradually increases as the diesel engine 1 is operated. Then, the detected differential pressure also gradually increases, but the detected differential pressure is not linear but increases rapidly as the particle deposition amount increases. At this time, since the operating condition of the diesel engine 1 changes every moment, the flow rate of the exhaust gas 3 changes, and when the flow rate of the exhaust gas 3 changes, the detected differential pressure also changes and an error occurs. The command controller 15 inputs the detected exhaust flow rate 14a from the exhaust flow rate detector 14, and corrects the detected differential pressure 13a by the detected exhaust flow rate 14a to estimate the particle deposition amount.

  On the other hand, in FIG. 1, the engine state quantity 19 such as the engine speed 19 a and the fuel injection amount 19 b detected originally in the engine 1 is input to the regeneration command controller 15, and It also has a configuration that estimates the amount of particle deposition. Here, since the method for estimating the particle deposition amount from the state quantity 19 of the engine 1 is relatively easy, the main method is to estimate the particle deposition quantity from the state quantity 19 of the engine 1, and the differential pressure detector 13. The estimation of the particle deposition amount from the detected differential pressure 13a may be performed as a backup. Further, a method other than the above may be used as a method for estimating the amount of deposited particles.

  Therefore, the regeneration command controller 15 estimates the particle accumulation amount based on the relationship between the detected differential pressure and the estimated deposition value X in FIG. 2 when the detected differential pressure 13a from the differential pressure detector 13 is input. Therefore, the regeneration command controller 15 generates a regeneration processing command 16 for increasing the exhaust gas temperature for a set time when the detected differential pressure A, which is estimated to have reached the predetermined value B, is detected. It is designed to output. When the state quantity 19 of the engine 1 is input to the regeneration command controller 15, the regeneration command controller 15 regenerates when the particle accumulation amount estimated from the state quantity 19 of the engine 1 reaches a predetermined value. A processing command 16 is output.

  In the form of FIG. 1, the regeneration command controller 15 sends a regeneration processing command 16 to the addition valve 8 and the supply pump 9 so as to add a predetermined fuel addition amount for a set time T from the start of regeneration as shown in FIG. Thus, the fuel 12 is added to the upstream of the particulate filter 5 to increase the exhaust gas temperature, and the particulate filter 5 is regenerated.

  On the other hand, a regeneration time extension command controller 17 (regeneration time extension command means) is provided to input the detected differential pressure 13a of the differential pressure detector 13 and the detected exhaust flow rate 14a of the exhaust flow rate detector 14, and the regeneration time is provided. The extension command controller 17 is supplied with a regeneration processing command 16 from the regeneration command controller 15. The regeneration time extension command controller 17 detects the differential pressure by the differential pressure detector 13 and the exhaust flow rate by the exhaust flow rate detector 14 for a certain period after the output of the regeneration processing command 16 is completed (regeneration processing is completed). Is detected, and the amount of particles remaining in the particulate filter 5 is estimated based on the detected differential pressure 13a of the differential pressure detector 13. That is, even if the regeneration process is completed, the detected differential pressure in FIG. 2 does not recover to the initial value a0. For example, when the detected differential pressure a is indicated, the particulate filter 5 still has the remaining accumulation amount b. It can be estimated that it exists.

  Accordingly, the regeneration time extension command controller 17 stores the remaining accumulation amount b when detecting the remaining accumulation amount b larger than the arbitrarily set value b ′, and at the next regeneration processing, As shown in FIG. 4, with respect to the set time T of the regeneration processing command 16 instructed from the regeneration command controller 15, a command 18 for extending the processing time by the extension time t corresponding to the remaining deposition amount b is output. It has become. Here, the regeneration time extension command controller 17 may extend the regeneration time by issuing an addition command 18a for adding to the set time T by the extension time t corresponding to the remaining accumulation amount b. The command controller 17 issues a command 18b that multiplies the set regeneration time T by a low regeneration rate that slows the speed at which the particulates of the particulate filter 5 are combusted by the addition of the fuel 12, thereby slowing the regeneration speed. The playback time may be substantially extended.

  In the embodiment shown in FIG. 1, a case has been described in which the fuel addition device 11 is provided to increase the catalyst bed temperature of the particulate filter 5 by adding the fuel 12 to the exhaust gas 3. As a technique for raising the bed temperature, fuel is injected into the exhaust gas by performing post-injection at a non-ignition timing later than the compression top dead center following the main injection of fuel performed near the compression top dead center of the diesel engine 1. In the method of increasing the catalyst bed temperature of the particulate filter 5 by post-injection as described above, if the remaining deposition amount b is detected after the regeneration process, the regeneration time is extended. The command controller 17 performs control so as to extend the set time T for the next post injection.

  The operation of the exhaust emission control device will be described with reference to FIG. 1 and FIG. 5 shown in the control flowchart. The regeneration command controller 15 receives the detected differential pressure 13a from the differential pressure detector 13 and the detected exhaust flow rate 14a from the exhaust flow rate detector 14. The regeneration command controller 15 receives the estimated deposition value shown in FIG. Based on X, the particle deposition amount of the particulate filter 5 is always estimated from the detected differential pressure 13a (step 1). The regeneration command controller 15 receives engine state quantities 19 such as an engine speed 19a and a fuel injection amount 19b. Therefore, the particulate accumulation amount of the particulate filter 5 is always determined by the state quantity 19 as well. Can be estimated.

  When the regeneration command controller 15 detects the detected differential pressure A estimated that the amount of deposited particles has reached the predetermined value B, the regeneration command controller 15 increases the exhaust gas temperature for a set time. Is output (step 2). In the form of FIG. 1, a regeneration processing command 16 for performing a predetermined fuel addition amount for a set time T is output to the addition valve 8 and the supply pump 9 as shown in FIG. The fuel 12 is added to the exhaust gas upstream of the particulate filter 5 and the catalyst bed temperature of the particulate filter 5 is raised, whereby the particulate filter 5 is regenerated (step 3).

  When the regeneration process is completed, the regeneration time extension command controller 17 receiving the regeneration process command 16 detects the completion of the regeneration process, and the regeneration time extension command controller 17 detects the differential pressure in a certain period. Based on the detected differential pressure 13a by the detector 13 and the detected differential pressure 13a, the residual deposition amount b of the particulates of the particulate filter 5 is estimated from the estimated deposition value X in FIG. 2 (step 4). When the remaining amount b of particles is larger than the set value b '(when the detected differential pressure 13a is larger than a predetermined value), the remaining amount b is stored (step 5).

  In the next regeneration process, as shown in FIG. 4, an addition command 18a for adding the extension time t corresponding to the stored remaining accumulation amount b to the set time T or a low regeneration rate is multiplied by the set time T. The command 18b is output to the regeneration command controller 15.

  As a result, at the next regeneration process, for example, the rise in the exhaust gas temperature is extended by the set time T + the extension time t, so that the remaining accumulated particles are burned out at the next regeneration process. The performance of the particulate filter 5 is always recovered stably (step 6).

  As described above, in the exhaust gas purification apparatus of the present invention, the regeneration process of the particulate filter 5 with a simple and inexpensive configuration comprising the differential pressure detector 13, the regeneration command controller 15, and the regeneration time extension command controller 17. Can be performed stably and reliably.

  The exhaust emission control device of the present invention is not limited to the above-described embodiment, and is not limited to a technique for increasing the exhaust gas temperature to perform the regeneration process. Of course, various modifications can be made within the range not to be performed.

DESCRIPTION OF SYMBOLS 1 Diesel engine 3 Exhaust gas 4 Exhaust pipe 5 Particulate filter 13 Differential pressure detector (Differential pressure detection means)
13a Detected differential pressure 15 Regeneration command controller (Regeneration command means)
16 Reproduction processing command 17 Reproduction time extension command controller (reproduction time extension command means)
18 Command a Detected differential pressure b Residual accumulation amount b 'Set value t Extension time

Claims (1)

Exhaust gas purification is equipped with a particulate filter in the exhaust passage of the diesel engine, and when the particulate filter needs to be regenerated due to particle accumulation, the exhaust gas temperature is raised to regenerate the particulate filter. In the device
Estimating the amount of accumulated particles in the particulate filter using at least one of the detected differential pressure from the differential pressure detecting means for detecting the differential pressure before and after the particulate filter and the state quantity of the engine, and the estimated accumulated amount of particles Regeneration command means for outputting a regeneration processing command so that the exhaust gas temperature is raised for a set time when becomes a set value;
After the output of the regeneration processing command by the regeneration command means is completed, the residual amount of particles is estimated by detecting the differential pressure by the differential pressure detection means for a certain period, and the residual amount of particles is larger than the set value The exhaust gas purification apparatus further comprises a regeneration time extension command means for storing the remaining deposition amount and instructing to extend the regeneration processing time in accordance with the remaining deposition amount at the next regeneration processing. .

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