JP2006250048A - Regeneration control method of filter for exhaust emission control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regeneration control method of a filter for exhaust emission control capable of controlling the start and end of regeneration at optimum timings by accurately detecting the collecting limit of an exhausted soot amount and regenerating the filter without deteriorating fuel economy and without producing damage or melting loss on the filter. <P>SOLUTION: This regeneration control method comprises a first step for measuring the deposited soot amount collected and deposited in the filter for exhaust emission control by using soot sensors 41a and 41b, a second step for starting the regeneration of the filter for exhaust emission control or returning it to the first step according to determination of whether the value of a reference deposited soot amount set based on the deposited soot amount exceeds a regeneration start threshold or not, a third step for measuring a regeneration end index after starting the regeneration of the filter for exhaust emission control, and a fourth step for terminating the regeneration according to determination of whether the value of the regeneration end index exceeds the regeneration end threshold or not or returning it to the third step. Thus, the filter for exhaust emission control can be controllably regenerated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas purification filter regeneration control method, a regeneration control system, and a regeneration control program. More specifically, an exhaust gas purification filter (for example, an exhaust particulate purification filter (DPF) or the like) used for purifying exhaust gas discharged from a diesel engine or the like collects soot (eg, soot) collected in an exhaust gas purification filter (DPF: Diesel Particulate Filter, etc.). ) And the regeneration control method, the regeneration control system, and the regeneration control program.

  Diesel engine is a power source with excellent fuel efficiency and durability, and HC and CO emitted from the engine is less than gasoline engine, so it is a preferable internal combustion engine against global warming, which has become a problem in recent years. is there. However, in a diesel engine, there are more NOx and exhaust particulates (soot) generated during the combustion of the air-fuel mixture than in a gasoline engine, and it is an urgent issue to reduce this NOx and soot from exhaust gas. In this regard, an oxidation catalyst is provided in the exhaust gas flow path from the diesel engine, and further, a DPF having a ceramic porous wall as a filter element is provided on the downstream side thereof, in the exhaust gas discharged from the diesel engine. NOx, CO, HC, etc. are oxidized by an oxidation catalyst, and when the oxidized exhaust gas passes through the porous wall of the DPF, the exhaust gas collects the soot contained in the exhaust gas at the pores. Purification systems are known.

In this exhaust gas purification system, when soot is collected at the pore portion and the wall surface in the filter wall and the collected soot is removed by combustion (regeneration), the amount of collected soot is too large. Since the filter may be damaged by overheating during combustion, there is a limit to the amount of soot that can be collected by the filter. As a method of detecting the collection limit soot amount, an exhaust gas pressure difference (sometimes referred to as “pressure loss” or “pressure loss” for short) and an exhaust gas temperature on the upstream side and downstream side of the DPF are detected. A method for predicting the soot amount accumulated in the filter and detecting that the DPF is at the collection limit based on the predicted value (see Patent Document 1), and the fuel injection amount, the engine speed, and the exhaust gas A method of predicting the exhaust soot amount from mapping of gas temperature and the like and detecting that the DPF is at the collection limit based on the integrated amount is disclosed (see Patent Document 2).
JP 60-47937 A Japanese Patent Laid-Open No. 5-18228

  However, in the method for detecting that the DPF is at the collection limit from the pressure difference between the upstream side and the downstream side of the DPF as disclosed in Patent Document 1, the amount of accumulated soot before and after the DPF regeneration The relationship with the pressure loss has hysteresis, which has the disadvantage that the accuracy of the soot amount predicted from the pressure loss is poor. Further, as disclosed in Patent Document 2, a method for predicting the exhaust soot amount from the mapping of the fuel injection amount, the engine speed, the exhaust gas temperature, etc., and detecting that the DPF is at the collection limit, Due to individual variations in fuel injectors and fluctuations over time, an error occurs between the commanded fuel injection amount and the actual fuel injection amount, resulting in inconvenience that the accuracy of estimating the exhaust soot amount deteriorates.

  In order to eliminate the inconveniences described above, the DPF regeneration was conventionally performed by reducing the predicted soot amount to be regenerated. However, if the soot accumulation amount at the time of regeneration is decreased, the regeneration interval is shortened and the fuel consumption is deteriorated. When the soot accumulation amount is small, the soot regeneration is finished while leaving a portion where the soot cannot be completely regenerated due to the variation in the amount of adhering soot at the position in the DPF. There was also a problem of end up.

  The present invention has been made in view of the above-described problems. It is possible to detect the collection limit of the discharged soot amount with high accuracy, and to control the start and end of regeneration at the optimum timing, thereby deteriorating fuel consumption. An object of the present invention is to provide a regeneration control method, a regeneration control system, and a regeneration control program for an exhaust gas purifying filter that can be evenly regenerated without causing damage and melting of the filter.

  In order to achieve the above object, according to the present invention, the following regeneration control method, regeneration control system, and regeneration control program for an exhaust gas purification filter are provided.

[1] Exhaust gas for controlling the start and end timings of combustion of the soot when the exhaust gas purification filter is regenerated by burning and removing the soot collected and accumulated in the exhaust gas purification filter A method for controlling regeneration of a gas purification filter, comprising: a first step of measuring a soot accumulation amount collected and deposited by the exhaust gas purification filter using a soot sensor; and a measurement in the first step. The regeneration of the exhaust gas purification filter is started according to whether the value of the reference soot accumulation amount set based on the soot accumulation amount is not less than the regeneration start threshold value, or the first A second step of returning to the step, and a predetermined regeneration end index serving as an index for ending the regeneration after the regeneration of the exhaust gas purification filter is started. A third step for determining, and a fourth step for terminating the reproduction or returning to the third step depending on whether or not the value of the reproduction end index is equal to or greater than a reproduction end threshold; An exhaust gas purification filter regeneration control method comprising:

[2] The value according to [1], wherein a value obtained by subtracting an estimated accumulated self-regeneration amount from the soot accumulation value is used as the reference soot accumulation value set based on the soot accumulation amount. Control method for the exhaust gas purification filter.

[3] The regeneration control method for an exhaust gas purification filter according to [1] or [2], wherein the exhaust gas temperature after passing through the exhaust gas purification filter is used as the regeneration end index. .

[4] The regeneration control method for an exhaust gas purification filter according to any one of [1] to [3], wherein an instantaneous soot concentration measurement type or an accumulated soot amount measurement type is used as the soot sensor.

[5] Regeneration of the exhaust gas purifying filter according to [4], wherein the soot sensor of the instantaneous soot concentration measurement type uses a sensor that measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot. Control method.

[6] As described in [4], the soot sensor of the cumulative soot amount measurement type uses a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control method for the exhaust gas purification filter.

[7] Controlling the start and end timing of combustion of the soot when the exhaust gas purification filter is regenerated by burning and removing the soot collected and accumulated in the exhaust gas purification filter A regeneration control system for an exhaust gas purifying filter capable of performing soot, and a soot accumulation amount having a soot sensor and capable of measuring the soot accumulation amount collected and accumulated in the exhaust gas purification filter by the soot sensor And the reference soot accumulation amount set based on the soot accumulation amount measured by the soot accumulation amount measuring means is greater than or equal to a regeneration start threshold value. Regeneration capable of starting the regeneration of the filter or returning to the measurement of the soot deposition amount by the soot deposition amount measuring means Start determination means, regeneration end index measuring means capable of measuring a predetermined regeneration end index serving as an index for ending regeneration after the start of regeneration of the exhaust gas purification filter, and Reproduction end determination means capable of ending reproduction or returning to measurement of the reproduction end index of the reproduction end index measuring means depending on whether or not the value is equal to or greater than a reproduction end threshold. An exhaust gas purification filter regeneration control system characterized by that.

[8] The estimated accumulated self-regeneration amount is subtracted from the soot accumulation value as a reference soot accumulation amount value set based on the soot accumulation amount measurement means measured by the soot collection accumulation amount measuring means. The regeneration control system for an exhaust gas purifying filter according to [7], wherein the obtained value is used.

[9] The regeneration control system for an exhaust gas purification filter according to [7] or [8], wherein the regeneration end index is a temperature of the passing gas after the exhaust gas has passed through the exhaust gas purification filter. .

[10] The regeneration control system for an exhaust gas purification filter according to [7] to [9], wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.

[11] The regeneration of the exhaust gas purifying filter according to [10], wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount, or a scattering amount at an instant of the soot. Control system.

[12] The accumulated soot amount measurement type soot sensor measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Regeneration control system for exhaust gas purification filter.

[13] To control the start and end timing of the soot combustion when regenerating the exhaust gas purification filter by burning and removing the soot collected and accumulated in the exhaust gas purification filter A computer readable regeneration control program for an exhaust gas purification filter, wherein the computer can function as the following means (1) to (4): Filter regeneration control program.
(1) Soot deposition amount measuring means capable of causing the soot sensor to measure the soot deposition amount collected and deposited by the exhaust gas purification filter;
(2) The exhaust gas purification filter according to whether or not a value of a reference soot accumulation amount set based on the soot accumulation amount measured by the soot accumulation amount measuring means is equal to or greater than a regeneration start threshold value. Regeneration start determination means capable of starting the regeneration of the soot accumulation amount, or returning to the measurement of the soot accumulation amount by the soot accumulation amount measurement means,
(3) A regeneration end index measuring means capable of measuring a predetermined regeneration end index serving as an index for ending regeneration after the start of regeneration of the exhaust gas purification filter;
(4) Depending on whether or not the value of the reproduction end index is equal to or greater than the reproduction end threshold, it is possible to end the reproduction or return to the measurement of the reproduction end index of the reproduction end index measuring means. Playback end determination means.

[14] Obtained by subtracting the estimated accumulated self-regeneration amount from the soot deposition amount value as a reference soot deposition amount value set based on the soot deposition amount measured by the soot deposition amount measuring means. The regeneration control program for an exhaust gas purifying filter according to [13], wherein a value is used.

[15] The regeneration control program for an exhaust gas purification filter according to [13] or [14], wherein the regeneration end index is a temperature of the passing gas after the exhaust gas has passed through the exhaust gas purification filter. .

[16] The regeneration control program for an exhaust gas purification filter according to any one of [13] to [15], wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.

[17] The regeneration of the exhaust gas purifying filter according to [16], wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot. Control program.

[18] The above-mentioned [16], wherein the soot sensor of the cumulative soot measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control program for exhaust gas purification filter.

  The “program” in the present invention means an ordered sequence of instructions suitable for processing by a computer. Specifically, it is installed in a computer HD (Hard Disk), CD-RW or the like. Means recorded on various recording media such as CD-ROM, DVD, FD, semiconductor memory, and computer HDD; and distributed via an external network such as the Internet.

  As described above, according to the present invention, it is possible to detect the collection limit of the discharge soot amount with high accuracy, and to control the start and end of regeneration at the optimum timing, and without reducing the fuel consumption and the filter. There are provided an exhaust gas purification filter regeneration control method, regeneration control system, and regeneration control program that can be evenly regenerated without causing damage or melting.

  The best mode for carrying out the present invention will be specifically described below. As described above, the regeneration control method for the exhaust gas purification filter of the present invention is used when the exhaust gas purification filter is regenerated by burning and removing the soot collected and accumulated in the exhaust gas purification filter. An exhaust gas purification filter regeneration control method for controlling the start and end timing of soot combustion, which includes first to fourth steps. Hereinafter, each step will be described in detail. Here, the present invention will be described focusing on the regeneration control method for the exhaust gas purifying filter, but basically the same applies to the regeneration control system and the regeneration control program.

(First step)
The first step is a step of measuring the soot accumulation amount collected and deposited by the exhaust gas purification filter using a soot sensor.

  Although there is no restriction | limiting in particular as a soot sensor used for a 1st step, For example, the thing of an instantaneous soot density | concentration measurement type or a cumulative soot amount measurement type can be mentioned. Examples of the soot sensor of the instantaneous soot concentration measurement type include a sensor that measures the amount of charge, the amount of transmitted light or the amount of scattering at the moment of soot. Further, examples of the soot sensor of the cumulative soot measurement type include a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the soot measurement. As a method of measuring the soot accumulation amount collected and accumulated in the exhaust gas purification filter using such a soot sensor, in the case of the instantaneous soot concentration measurement type, for example, the reference soot used in the previous second step is used. It can be mentioned that the accumulation amount is memorized, and the soot amount measured and converted by the instantaneous measurement soot concentration measurement type soot sensor is added to obtain the soot accumulation amount of this time, In the case of the cumulative soot measurement type, for example, the soot sensor output value can be used as the soot accumulation amount as it is.

(Second step)
The second step determines whether the reference soot accumulation amount set based on the soot accumulation amount measured in the first step is greater than or equal to the regeneration start threshold value. This is a step of starting reproduction or returning to the first step. Here, as the value of the reference soot accumulation amount set based on the soot accumulation amount, it is preferable to use a value obtained by subtracting the estimated accumulated self-regeneration amount from the value of the soot accumulation amount. The estimated cumulative self-regeneration amount is the cumulative amount of soot accumulated in the DPF that has been naturally burned and regenerated inside the DPF, and is a mapping obtained from the exhaust temperature, engine speed, accelerator opening, etc. It means the estimated amount of cumulative reproduction. Specifically, when an instantaneous soot concentration measurement type sensor is used as the soot sensor, it is obtained by subtracting the estimated self-regeneration amount from the total value obtained by adding the soot content contained in the exhaust gas to the soot accumulation amount. A value may be used, and when a soot sensor of the cumulative soot amount measurement type is used, a value obtained by subtracting the estimated cumulative self-regeneration amount from the value of the soot accumulation amount may be used. The soot content contained in the exhaust gas can be measured using the above-described soot sensor, but may be the same as or different from that used in the first step. Also good.

  The regeneration start threshold is set, for example, by experimentally obtaining the regeneration limit amount of soot deposition inside the DPF by the system. The threshold value should be changed variously depending on the material, shape, volume, etc. of the DPF. In addition, regeneration of the exhaust gas purification filter, for example, by allowing a small amount of fuel to reach the oxidation catalyst before the DPF without burning in the engine for DPF regeneration, such as post injection, and the unburned gas burns there, For example, a heater for increasing the inlet temperature of the DPF for a certain period of time or heating the DPF main body may be installed so that the heater is turned on during regeneration.

(Third step)
The third step is a step of measuring a predetermined regeneration end index serving as an index for ending regeneration after the start of regeneration of the exhaust gas purification filter.

  Examples of the regeneration end index include the temperature of the passing gas after the exhaust gas passes through the exhaust gas purification filter, the pressure difference before and after the DPF, and the like. When the temperature of the passing gas after the exhaust gas passes through the exhaust gas purifying filter is used, specifically, it is set by experimentally obtaining the exhaust gas temperature at the end of regeneration according to the system. It is considered that the exhaust gas temperature at the end of the regeneration takes various values depending on the material, shape, volume, etc. of the DPF. As a method for measuring the regeneration end index, for example, a temperature sensor can be installed downstream of the DPF, a pressure sensor can be installed before and after the DPF, and the difference can be seen.

(Fourth step)
The fourth step is a step for terminating the reproduction or returning to the third step depending on whether or not the value of the reproduction end index is equal to or greater than the reproduction end threshold.

  The playback end threshold is set, for example, by experimentally obtaining a playback end index at the end of playback by the system. The threshold value should be changed variously depending on the material, shape, volume, etc. of the DPF. The regeneration can be terminated, for example, by terminating the post injection or turning off the DPF regeneration heater.

  Hereinafter, the case where the regeneration control method for an exhaust gas purifying filter of the present invention is applied to a control system of an engine system of a vehicle (diesel vehicle) equipped with a diesel engine will be specifically described with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing a control system of an engine system of a diesel vehicle to which the present invention is applied. As shown in FIG. 1, an intake port of a diesel engine (hereinafter also referred to as “engine”) 11 is connected to an intake pipe 13b via an intake manifold 13a, and an exhaust port is connected to an exhaust pipe via an exhaust manifold 16a. A tube 16b is connected. An exhaust passage 16 is constituted by the intake manifold 16a and the exhaust pipe 16b. The intake pipe 13b is provided with a compressor 17a of a turbocharger 17 provided with a supercharging pressure control means, and an intercooler 18 for cooling the intake air compressed by the turbocharger 17, and the exhaust pipe 16b is provided with an exhaust pipe 16b. A turbine 17b of the turbocharger 17 is provided. Although not shown, the rotor blades of the compressor 17a and the rotor blades of the turbine 17b are connected by a shaft. The compressor 17a is rotated via the turbine 17b and the shaft by the energy of the exhaust gas discharged from the engine 11, and the intake air in the feeder pipe 13b is compressed by the rotation of the compressor 17a.

  Further, an oxidation catalyst 21 such as a platinum-based catalyst that functions as a NOx catalyst and an oxidation catalyst, and a DPF 22 are provided in the middle of the exhaust pipe 16b in order from the engine side (exhaust gas upstream side). The oxidation catalyst 21 and the DPF 22 are accommodated in a cylindrical collector 24 in which the diameter of the exhaust pipe 16b is enlarged. An intake throttle valve 26 capable of adjusting the flow rate of intake air is provided in the intake pipe 13b upstream of the compressor 17a.

  The platinum catalyst of the oxidation catalyst 21 is a platinum-alumina catalyst, a platinum-zeolite catalyst, or a platinum-zeolite-alumina catalyst. The platinum-alumina catalyst is formed by coating Pt on a honeycomb carrier made of cordierite after coating a slurry containing γ-alumina powder. The platinum-zeolite catalyst is formed by coating a honeycomb carrier made of cordierite with a slurry containing hydrogen ion-exchanged zeolite powder (H-ZSM-5) and then supporting Pt. Further, the platinum-zeolite-alumina catalyst is formed by coating a honeycomb carrier made of cordierite with a slurry containing hydrogen ion-exchanged zeolite powder (H-ZSM-5) and γ-alumina powder, and then supporting Pt. .

  The DPF 22 has a honeycomb structure, and as shown in FIG. 2, the porous DPF 22 is made of ceramics such as cordierite and SiC (gas is allowed to pass through but soot is blocked by blocking its passage (blocking outflow)). A partition wall 22a having a plurality of pores (pores) having a diameter that can be used as a filter element, and a cell partitioned by the partition wall 22a, for example, having a polygonal cross section and serving as a fluid flow path. Have.

  The DPF 22 is configured by alternately and alternately staggering the entrance side cells 22c and the exit side cells 22d of the cells 22b formed in parallel with each other by the partition walls 22a. Further, a noble metal such as Pt and Pd may be directly supported on the partition wall 22a, and after coating a slurry containing γ-alumina powder on the partition wall 22a, a noble metal such as Pt and Pd is supported on the DPF 22 so You may provide the oxidizing power of hydrocarbon (HC).

  FIG. 2 is an enlarged cross-sectional view schematically showing a DPF used in the present invention. As shown in FIG. 2, the exhaust gas E1 exhausted from the engine 11 is oxidized as NO, CO, and HC components contained in the gas via the oxidation catalyst 21, and then is used as a high-temperature exhaust gas resulting from the oxidation reaction. It flows into the DPF 22 from the open side cell in the entrance side cell 22c of the DPF 22, passes through the plurality of pores of the partition wall 22a, flows into the adjacent cell, and is exhausted through the exit side cell 22d at the open end. Further, when the exhaust gas E1 passes through each pore of the partition wall 22a, the soot contained in the exhaust gas E1 is blocked from flowing out to the adjacent cell by each pore, and is accumulated in each pore and on the surface of the partition wall 22a. The amount of soot contained in the exhaust gas E2 that has passed through can be greatly reduced.

  The engine 11 is also provided with an EGR (Exhaust Gas Recirculation) control valve for recirculating exhaust gas to intake air for the purpose of reducing NOx in exhaust components and improving fuel efficiency. In addition, an EGR cooler is provided that cools the exhaust when it is turned to intake air again.

  Further, a temperature sensor 36 for detecting the exhaust gas temperature in the exhaust pipe 16b is provided at the exhaust pipe 16b between the turbine 17b and the collector 24, that is, at the entrance of the oxidation catalyst 21, and also at the outlet side of the DPF 22. A temperature sensor 42 for measuring the temperature of the passing gas after the exhaust gas has passed through the DPF 22 is provided. Detection outputs of the temperature sensor 36 and the temperature sensor 42 are connected to a control input of an ECU (Electronic Control Unit) 37 formed of a microcomputer. Other control inputs of the ECU 37 include a rotation sensor 38 that detects the rotation speed of the engine 11, an accelerator opening change sensor 39 that detects changes in the accelerator opening and the accelerator change speed, and the amount contained in the exhaust gas of the soot. The respective detection outputs of the soot sensor 41a for measuring (content), the soot sensor 41b for measuring the amount (deposition amount) collected and deposited in the DPF 22 of the soot, and the travel distance sensor 50 for detecting the travel distance of the vehicle are It is connected.

  A suitable example of the soot sensor 41a is an instantaneous soot concentration measurement type, and an example of the soot sensor 41b is a cumulative soot amount measurement type. Examples of the soot sensor of the instantaneous soot concentration measurement type include a sensor that measures the amount of charge, the amount of transmitted light or the amount of scattering at the moment of soot. Further, examples of the soot sensor of the cumulative soot measurement type include a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the soot measurement. In the case of the cumulative soot amount measurement type, a heater for burning out the soot adhering to the sensor element may be provided.

  In addition, the ECU 37 includes a memory 43. In the memory 43, the opening / closing control of the EGR control valve 20, the opening / closing control of the intake throttle valve 26, and the air generated by the rotation of the compressor 17a according to the engine rotation, exhaust gas temperature, travel distance, accelerator opening, accelerator change speed, etc. A program for performing intake amount control and the like and for instructing the engine 11 to start regeneration of the DPF 22 is stored in advance.

  Further, the fuel injector 40 of the engine 11 is electrically connected to the ECU 37, and the ECU 37 instructs the fuel injector 40 about the fuel injection timing and the fuel injection amount.

  FIG. 3 is a flowchart schematically showing a control operation in a control system of an engine system of a diesel vehicle when an instantaneous soot concentration measurement type soot sensor is used.

As shown in FIG. 3, first, an output value A of an instantaneous soot concentration measurement type soot sensor 41a is read by the ECU 37 (see FIG. 1; the same reference numerals are used hereinafter) (step S01). FIG. 5 schematically shows the relationship between the soot sensor output value and time (when the soot content (discharge) amount is substantially constant) when the soot sensor 41a of the instantaneous soot concentration measurement type is used. Next, the soot accumulation amount Xt is given by adding the output value A of the soot sensor 41a read in step S01 this time to the previous reference soot accumulation amount X (step S02). Next, the exhaust temperature is read from the temperature sensor 36, the engine speed is read from the rotation sensor 38, the accelerator opening is read from the accelerator opening sensor 39, and the self-regeneration amount Y in the DPF 22 is estimated from those values. (Step S03). FIG. 7 schematically shows the relationship between the exhaust temperature and the self-regeneration amount when the engine speed and the accelerator opening are constant. Next, the reference soot accumulation amount X is obtained by subtracting the self-regeneration amount Y estimated in step S03 from the soot accumulation amount Xt (step S04). Next, it is determined whether or not the reference soot accumulation amount X is equal to or greater than the regeneration start threshold value G ₀ (see FIG. 8) (step S05). Then, if it is not reproduction start threshold G ₀ or performs the process from (NO), step S01 again. On the other hand, when the reference soot accumulation amount X is equal to or larger than the regeneration start threshold value G ₀ (YES), a DPF 22 regeneration start command is output to the engine 11 (step S06). Next, the exhaust temperature Z on the outlet side of the DPF 22 is read from the temperature sensor 42 (step S07), and it is determined whether or not the exhaust temperature Z is less than the regeneration end threshold T ₀ (see FIG. 9) (step S08). If it is not less than the reproduction end threshold T ₀ (NO), the processing is performed again from step S 07. On the other hand, if the exhaust temperature Z on the outlet side of the DPF 22 is less than the regeneration end threshold value T ₀ (YES), the reference soot accumulation amount X is set to 0 (step S09), and the processing is performed again from step S01. Note that a reproduction end signal may be directly received from the engine 11 instead of steps S07 and S08. Alternatively, the end of regeneration may be determined using a differential pressure sensor.

  As described above, when an instantaneous soot concentration measurement type soot sensor is used, the ECU 37 controls the start of regeneration of the DPF 22 using the output value of the soot sensor 41, so that the accumulated soot amount is predicted from the pressure loss and the exhaust temperature. It can be detected that the DPF is at the collection limit with higher accuracy than the method for detecting the collection limit. Thereby, it is possible to prevent the soot amount exceeding the collection limit amount from being accumulated in the DPF 22, and it is possible to prevent the filter itself from being damaged or melted due to an excessive temperature rise during regeneration. Further, it is possible to prevent the amount of accumulated soot at the start of regeneration from being too small, and therefore, variation in the amount of adhering soot at the position in the DPF can be suppressed, so that the accumulated soot in the DPF is completely regenerated in all parts. Therefore, it can be determined whether or not all the soot in the DPF has been regenerated only by the exhaust temperature at the outlet side of the DPF 22, and the problem of deterioration in fuel consumption can also be solved.

  FIG. 4 is a flowchart schematically showing a control operation in a control system of an engine system of a diesel vehicle when a soot sensor of a cumulative soot amount measurement type is used.

As shown in FIG. 4, first, an output value Xt of a soot sensor 41b of the cumulative soot amount measurement type is read by the ECU 37 (see FIG. 1; the same reference numerals are used hereinafter) (step S11). FIG. 6 schematically shows the relationship between the soot sensor output value Xt and time (when the soot content (discharge) amount is substantially constant) when the cumulative soot amount measurement type soot sensor 41b is used. Next, the exhaust temperature is read from the temperature sensor 36, the engine speed is read from the rotation sensor 38, the accelerator opening is read from the accelerator opening sensor 39, and the self-regeneration amount A in the DPF 22 is estimated from these values. (Step S12), the accumulated self-regeneration amount Y is added (Step S13). Next, a reference soot accumulation amount X is obtained by subtracting the cumulative self-regeneration amount Y from the soot sensor output value Xt, which is the soot accumulation amount (step S14). It is determined whether or not the reference soot accumulation amount X is equal to or greater than the regeneration start threshold value G ₀ (see FIG. 8) (step S15). When not reproducing threshold G ₀ or performs the process from (NO), step S11 again. On the other hand, if the result of subtracting the accumulated self-regeneration amount Y from the soot sensor output value X is equal to or greater than the regeneration threshold value G ₀ (YES), a DPF 22 regeneration start command is output to the engine 11 and soot sensor regeneration is performed to the soot sensor 41b. If a heater is provided, the soot sensor regeneration heater is turned on (step S16). Next, the exhaust temperature Z on the outlet side of the DPF 22 is read from the temperature sensor 42 (step S17), and it is determined whether or not the exhaust temperature Z is less than the regeneration end threshold value T ₀ (see FIG. 9) (step S18). If it is not less than the reproduction end threshold T ₀ (NO), the processing is performed again from step S17. On the other hand, when the exhaust gas temperature Z of the outlet side of the DPF22 is less than the playback end threshold value T ₀ (YES), the cumulative self-renewal amount Y 0, if the Sutosensa 41b are heaters Sutosensa for reproduction is provided The heater for regeneration of the soot sensor is turned off (step S19), and the processing is performed again from step S11. Note that a reproduction end signal may be directly received from the engine 11 instead of steps S17 and S18. Alternatively, the end of regeneration may be determined using a differential pressure sensor.

  As described above, when the soot sensor of the cumulative soot amount measurement type is used, if the soot sensor 41b includes a heater for regeneration of the soot sensor, in addition to the above-described effect when the soot sensor 41a of the instantaneous soot concentration measurement type is used. Furthermore, by reproducing the soot sensor during the regeneration of the DPF, it is possible to maintain a good correlation between the soot accumulation amount in the DPF and the soot sensor output value.

  The present invention is effectively used in various industrial fields such as the automobile industry for manufacturing various vehicles equipped with diesel engines.

It is explanatory drawing which shows typically the control system of the engine system of the diesel vehicle to which this invention is applied. It is an expanded sectional view showing typically DPF used for the present invention. It is a flowchart figure which shows typically the control action in the control system of the engine system of a diesel vehicle at the time of using the soot sensor of an instantaneous soot concentration measurement type. It is a flowchart figure which shows typically the control action in the control system of the engine system of a diesel vehicle at the time of using a soot sensor of a cumulative soot amount measurement type. In the first step, when an instantaneous soot concentration measurement type soot sensor is used, it is a graph schematically showing the relationship between the soot sensor output value and time (when the soot content (discharge) amount is substantially constant). When a cumulative soot concentration measurement type soot sensor is used in the first step, it is a graph schematically showing the relationship between the soot sensor output value and time (when the soot content (discharge) amount is substantially constant). In a 2nd step, it is a graph which shows typically the relation between self-regeneration amount and exhaust gas temperature. 6 is a graph schematically showing that regeneration of the exhaust gas purification filter is started when the soot accumulation amount is equal to or greater than a regeneration start threshold in the third step. In a 4th step, when the value of a regeneration end index (exhaust gas temperature) is more than a regeneration end threshold, it is a graph which shows typically that regeneration ends.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Diesel engine, 21 ... Oxidation catalyst, 22 ... DPF, 36 ... Temperature sensor, 37 ... ECU (computer), 38 ... Rotation sensor, 39 ... Accelerator opening change sensor, 41a ... Soot sensor of instantaneous soot concentration measurement type, 41b ... soot sensor of cumulative soot concentration measurement type, 42 ... temperature sensor, 43 ... memory, 50 ... mileage sensor.

Claims (18)

For exhaust gas purification for controlling the start and end timing of combustion of the soot when regenerating the exhaust gas purification filter by burning and removing the soot collected and accumulated in the exhaust gas purification filter A filter regeneration control method,
A first step of measuring a soot accumulation amount collected and accumulated in the exhaust gas purification filter using a soot sensor;
The regeneration of the exhaust gas purification filter is started depending on whether or not the value of the reference soot deposition amount set based on the soot deposition amount measured in the first step is equal to or greater than a regeneration start threshold value. A second step that allows or returns to the first step;
A third step of measuring a predetermined regeneration end index serving as an index for ending regeneration after the start of regeneration of the exhaust gas purification filter;
A fourth step of ending the regeneration or returning to the third step depending on whether the value of the regeneration end index is equal to or greater than a regeneration end threshold value. A regeneration control method for a gas purification filter.   The exhaust gas purification according to claim 1, wherein a value obtained by subtracting an estimated cumulative self-regeneration amount from a value of the soot accumulation amount is used as the value of the reference soot accumulation amount set based on the soot accumulation amount. Filter regeneration control method.   The regeneration control method for an exhaust gas purification filter according to claim 1 or 2, wherein the temperature of the passing gas after the exhaust gas passes through the exhaust gas purification filter is used as the regeneration end index.   The regeneration control method for an exhaust gas purifying filter according to any one of claims 1 to 3, wherein an instantaneous soot concentration measurement type or an accumulated soot amount measurement type is used as the soot sensor.   The method for controlling regeneration of an exhaust gas purification filter according to claim 4, wherein the soot sensor of the instantaneous soot concentration measurement type uses a sensor that measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.   The exhaust gas purification according to claim 4, wherein the soot sensor of the cumulative soot amount measurement type uses a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Filter regeneration control method. It is possible to control the timing of the start and end of combustion of the soot when the exhaust gas purification filter is regenerated by burning and removing the soot collected and accumulated in the exhaust gas purification filter. A regeneration control system for an exhaust gas purification filter,
A soot deposition amount measuring means capable of measuring a soot deposition amount collected by the exhaust gas purification filter and deposited by the soot sensor;
The exhaust gas purification filter is regenerated depending on whether or not a reference soot accumulation value set based on the soot accumulation amount measured by the soot accumulation amount measuring means is equal to or greater than a regeneration start threshold value. A regeneration start determination means capable of starting or returning to the measurement of the soot deposition amount by the soot deposition amount measurement means;
A regeneration end index measuring means capable of measuring a predetermined regeneration end index serving as an index for ending regeneration after the start of regeneration of the exhaust gas purification filter;
A playback end determination that can end the playback or return to the measurement of the playback end index of the playback end index measuring means depending on whether the value of the playback end index is equal to or greater than the playback end threshold. And a regeneration control system for the exhaust gas purifying filter.   A value obtained by subtracting the estimated accumulated self-regeneration amount from the soot accumulation value as the reference soot accumulation value set based on the soot accumulation amount measured by the soot collection accumulation amount measuring means. The regeneration control system for the exhaust gas purifying filter according to claim 7, wherein:   The regeneration control system for an exhaust gas purification filter according to claim 7 or 8, wherein the regeneration end index is a temperature of a passing gas after the exhaust gas has passed through the exhaust gas purification filter.   The regeneration control system for an exhaust gas purification filter according to any one of claims 7 to 9, wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.   The regeneration control system for an exhaust gas purification filter according to claim 10, wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.   The exhaust gas purification according to claim 10, wherein the soot sensor of the cumulative soot measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Filter regeneration control system. A computer for controlling the start and end timings of combustion of the soot when the exhaust gas purification filter is regenerated by burning and removing the soot collected and accumulated in the exhaust gas purification filter Is a regeneration control program for an exhaust gas purification filter that can be read,
An exhaust gas purification filter regeneration control program capable of causing the computer to function as the following means (1) to (4).
(1) Soot deposition amount measuring means capable of causing the soot sensor to measure the soot deposition amount collected and deposited by the exhaust gas purification filter;
(2) The exhaust gas purification filter according to whether or not a value of a reference soot accumulation amount set based on the soot accumulation amount measured by the soot accumulation amount measuring means is equal to or greater than a regeneration start threshold value. Regeneration start determination means capable of starting the regeneration of the soot accumulation amount, or returning to the measurement of the soot accumulation amount by the soot accumulation amount measurement means,
(3) A regeneration end index measuring means capable of measuring a predetermined regeneration end index serving as an index for ending regeneration after the start of regeneration of the exhaust gas purification filter;
(4) Depending on whether or not the value of the reproduction end index is equal to or greater than the reproduction end threshold, it is possible to end the reproduction or return to the measurement of the reproduction end index of the reproduction end index measuring means. Playback end determination means.   A value obtained by subtracting the estimated cumulative self-regeneration amount from the soot deposition amount value is used as a reference soot deposition amount value set based on the soot deposition amount measured by the soot deposition amount measuring means. The exhaust gas purification filter regeneration control program according to claim 13.   The regeneration control program for an exhaust gas purification filter according to claim 13 or 14, wherein the regeneration end index is a temperature of a passing gas after the exhaust gas has passed through the exhaust gas purification filter.   The regeneration control program for an exhaust gas purification filter according to any one of claims 13 to 15, wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.   The regeneration control program for an exhaust gas purifying filter according to claim 16, wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.   The exhaust gas purification according to claim 16, wherein the soot sensor of the cumulative soot measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Filter regeneration control program.

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