JP2009036080A - Exhaust gas purification control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To spend on catalyst activation or regeneration processing when an exhaust gas purification device 22 in which a NOx trap catalyst and an oxidation catalyst are supported on a PM collection filter (DPF) is provided in an exhaust passage 3 of a diesel engine 1. Minimize energy.
SOLUTION: Cylinder control means (intake shut-off valve 6) capable of stopping some cylinders by stopping gas inflow / outflow and fuel supply in each cylinder of an engine, and when requesting improvement in catalyst activity, At the time of NOx regeneration request, PM regeneration request, or S poisoning regeneration request, the number of stopped cylinders and the output of the working cylinder are determined and controlled according to the request and the requested driving force for the engine. Further, the air-fuel ratio of the exhaust discharged from the working cylinder and flowing into the exhaust purification device is controlled.
[Selection] Figure 1

Description

  The present invention relates to an exhaust gas purification control device for an internal combustion engine (particularly a vehicular diesel engine).

  A compression ignition type internal combustion engine such as a diesel engine has attracted attention from the viewpoint of improving the fuel consumption rate or reducing CO2. As an exhaust emission control device for a diesel engine, an oxidation catalyst that oxidizes HC, CO (and PM) in exhaust gas, and a NOx trap catalyst that adsorbs NOx when the exhaust air-fuel ratio is lean are known. The NOx trap catalyst desorbs and purifies adsorbed NOx (that is, NOx regeneration) by periodically making the exhaust air-fuel ratio rich and reducing atmosphere before the NOx adsorption amount saturates. Further, since the purification performance of the NOx trap catalyst is deteriorated by poisoning with S (sulfur) contained in the fuel, the S poisoning is periodically released (ie, S poisoning regeneration) at a high temperature and in a stoichiometric atmosphere. Yes.

  On the other hand, particulate matter PM (Particulate Matter) is contained in the exhaust of a diesel engine, and a filter (DPF; Diesel Particulate Filter) for collecting PM is known. Since this DPF causes fuel consumption and power performance deterioration due to an increase in exhaust pressure caused by PM accumulation, it is necessary to periodically remove and collect (that is, regenerate PM) the collected PM. In recent years, the above-mentioned oxidation catalyst and NOx trap catalyst are supported on this DPF to simultaneously reduce the HC, CO, PM, and NOx contained in the exhaust gas. "Exhaust gas purification device" has been proposed (Patent Document 1).

  When this exhaust purification device is disposed in the exhaust passage, it is necessary to periodically perform the NOx regeneration, S poison regeneration, and PM regeneration in order to maintain good exhaust purification performance. In addition, when performing such regeneration processing, or in order to maintain good exhaust purification performance, it is necessary to control the exhaust temperature (exhaust purification device temperature) and exhaust air-fuel ratio appropriate for each situation. is there.

  As a method of raising the temperature of the exhaust gas purification device, some cylinders are stopped by cylinder control (stopping inflow and out of working gas and stopping fuel injection), and the remaining working cylinders per cylinder are stopped. The exhaust temperature is raised by increasing the load, and the amount of oxygen flowing into the exhaust purification device is estimated when performing such cylinder control to perform NOx regeneration, S poison regeneration, and PM regeneration. A method of determining the number of cylinders to stop based on the estimated oxygen amount has been proposed (Patent Document 2).

  In addition, when the vehicle shifts to a deceleration state while the regeneration process is being performed, the fuel injection of all cylinders is stopped and the working gas flows only when the temperature of the exhaust purification device is equal to or higher than a predetermined temperature. The discharge is not stopped (intake and exhaust are performed) (Patent Document 2).

On the other hand, as a technology for preventing deterioration of the catalyst and the like, when performing fuel cut during vehicle deceleration, if the temperature of the exhaust purification device is equal to or higher than a predetermined temperature, all cylinders are stopped and A method for stopping the circulation of exhaust gas has also been proposed (Patent Document 3).
JP 2003-190793 A JP 2005-220880 A JP 2003-074385 A

  When an exhaust purification device for simultaneously reducing HC, CO, PM, and NOx is disposed in the exhaust passage, the activity of the catalyst is improved (promoted) or maintained regularly to maintain its exhaust purification performance. Therefore, NOx regeneration, S poisoning regeneration, and PM regeneration need to be carried out, and it is necessary to control the exhaust temperature (exhaust purification device temperature) and the exhaust air / fuel ratio appropriate for each process.

  Specifically, the oxidation activity of HC and CO is lean at about 200 ° C. or more, the adsorption activity of NOx is lean in the range of about 200 to 500 ° C., and the NOx regeneration is rich in the range of about 250 to 450 ° C. (λ ≦ 0). .8), S poison regeneration is stoichiometric or rich (λ ≦ 1) at about 600 ° C. or more, and PM regeneration works most effectively when it is controlled lean at about 400 ° C. or more when a catalyst is provided.

  Further, in Patent Document 2, when some cylinders are stopped to raise the temperature, the intake / exhaust amount per cylinder of the remaining working cylinders increases, exhaust pulsation increases, and oxygen flows into the exhaust purification device. The amount also pulsates, the peak value rises, the reaction of HC and the like is promoted, and the exhaust gas purifier may overheat.

  By the way, processes such as catalyst activity improvement and PM regeneration are performed in a state where the exhaust air-fuel ratio is lean, so that the concentration of oxygen remaining in the exhaust gas is high and the amount of oxygen is large. On the other hand, since processing such as NOx regeneration and S poisoning regeneration is performed in a state where the exhaust air-fuel ratio is stoichiometric or rich, oxygen remaining in the exhaust does not theoretically exist and is actually extremely low. It exists only in concentration.

  Therefore, when processing such as catalyst activity improvement or PM regeneration is being performed, the concentration of oxygen flowing into the exhaust purification device is relatively high and large.

  However, in the research by the present inventors, when some cylinders are stopped, the load of the remaining working cylinders increases. However, in the case of a natural air supply engine, the change in the air filling rate due to the load is small and the peak of exhaust pulsation The increase in the fuel injection amount is not so large, and the increase in the fuel injection amount accompanying the increase in the load causes the excess air ratio to decrease and the oxygen concentration to decrease, so the oxygen amount also decreases. On the other hand, even in the case of an engine with a supercharger, if the load increases, the fuel injection amount increases and the exhaust temperature rises. Therefore, in order to increase the supercharging effect, the intake / exhaust amount per cylinder of the working cylinder is To increase. However, since the increase in the fuel injection amount accompanying the increase in the load exceeds the increase in the air filling rate due to supercharging, the excess air rate decreases and the oxygen concentration decreases, so the oxygen amount also decreases. Further, since the combustion temperature rises and the amount of HC decreases, even in the case of processing such as improvement of catalyst activity or PM regeneration, the reaction of HC or the like is promoted by the cylinder stop control, although the exhaust temperature increases. This will not cause an excessive increase in the temperature of the exhaust gas purification device.

  There is a high possibility that the exhaust purification device will overheat when the oxidation reaction (reburning) is performed at once when the PM accumulated in the exhaust purification device is relatively large. However, in order to prevent deterioration of power performance and fuel consumption due to an increase in back pressure due to PM accumulation, generally, the amount of PM accumulation on the exhaust purification device is set to about several grams per liter of the exhaust purification device. Compared with this, the weight of the exhaust gas flowing into the exhaust gas purification device is, for example, several hundred times to several thousand times per minute, which is overwhelmingly large with respect to the amount of combustion of PM, and the oxygen amount is several tens of times. From the first hundreds of times. In addition, when the cylinder stop control is performed and the exhaust temperature rises above the oxidation reaction temperature of PM (400 ° C. with catalyst, about 600 ° C. without catalyst), the oxygen concentration under the condition where the PM oxidation reaction is performed is Since it is low at about 10% or less, the oxidation reaction of PM is relatively slow even if the inflowing oxygen amount is overwhelmingly larger than the accumulated PM (generally several minutes for PM regeneration) The temperature rise of the exhaust purification device due to the reaction heat of PM is insignificant.

  On the other hand, from the condition that the exhaust gas temperature is relatively high and the temperature of the exhaust gas purification device is equal to or higher than the PM oxidation reaction temperature, particularly immediately after the start of PM regeneration, the vehicle shifts to a deceleration state and the oxygen concentration rapidly increases. (The fuel injection device of the diesel engine is cut when fuel is decelerated, so the oxygen concentration approaches 21% of the atmospheric concentration). Since PM re-combusts in an instant, the exhaust purification device overheats.

  Therefore, when processing such as catalyst activity improvement, NOx regeneration, S poison regeneration, PM regeneration, etc. is performed, an appropriate value is selected according to the state of the exhaust purification device (or various processing performed) and the required driving force. Cylinder control should be performed so that the exhaust gas temperature (exhaust gas purification device temperature) and the exhaust air / fuel ratio can be obtained. Further, various processes to be performed, particularly when changing from the PM regeneration to the deceleration state, the PM is instantaneously performed. It is necessary to prevent an excessive temperature rise of the exhaust gas purification device due to re-combustion.

  By the way, in Patent Document 2, when the vehicle shifts to a deceleration state during the regeneration process, the fuel injection of all cylinders is stopped only when the temperature of the exhaust purification device is equal to or higher than a predetermined temperature. The inflow and outflow of the working gas is not stopped (intake and exhaust are carried out). In this case, when the amount of accumulated PM is relatively large as described above, on the contrary, the oxidation reaction of PM proceeds at a stretch and the exhaust gas purification is performed. The device is likely to overheat.

  Further, in Patent Document 3, when fuel cut is performed in a vehicle deceleration state for the purpose of improving fuel consumption (in an oxygen-rich atmosphere), if the catalyst temperature is equal to or higher than a predetermined temperature (500 ° C.), all The cylinder is stopped and the flow of exhaust gas to the catalyst is also stopped to prevent the sintering of the catalyst. However, if the catalyst temperature is lower than a predetermined temperature (500 ° C.), all the cylinders are stopped without stopping. Since exhaust gas (in this case, air) is circulated through the catalyst, the catalyst is cooled.

  However, when using an exhaust purification device for simultaneously reducing HC, CO, PM, and NOx, the catalyst activity is improved, NOx regeneration, S poison regeneration, PM regeneration is performed in order to improve and recover the performance of the exhaust purification device. Since the control temperature range and the exhaust air / fuel ratio at this time are different, from the viewpoint of appropriately controlling the temperature and the exhaust air / fuel ratio, the temperature at the time of the vehicle deceleration state transition can be determined only by the temperature. It is inappropriate to determine whether or not to stop the cylinder.

  The present invention has been made in view of the above problems, and demands for exhaust temperature or exhaust air-fuel ratio based on the state of an exhaust purification device having a PM collection filter, a NOx trap catalyst, and an oxidation catalyst (request for improvement in catalyst activity). , NOx regeneration request, PM regeneration request, S poisoning regeneration request) and a required driving force detecting means for detecting a required driving force for the internal combustion engine. Then, by stopping the gas inflow / outflow and fuel supply in each cylinder of the internal combustion engine, some cylinders can be stopped, and the exhaust temperature or exhaust air / fuel ratio request based on the state of the exhaust purification device The cylinder control means for determining and controlling the number of stop cylinders and the output of the working cylinder according to the required driving force for the internal combustion engine, and the exhaust temperature or exhaust air-fuel ratio request based on the state of the exhaust purification device Exhaust air / fuel ratio control means is provided for controlling the air / fuel ratio of the exhaust gas discharged from the working cylinder and flowing into the exhaust gas purification device in accordance with the required driving force for the internal combustion engine.

  According to the present invention, the number of stopped cylinders, the output (load) of the working cylinders, and the exhaust purification according to the request for the exhaust temperature or the exhaust air-fuel ratio based on the state of the exhaust purification device and the required driving force for the internal combustion engine. The air-fuel ratio of the exhaust gas flowing into the system is appropriately controlled so that the exhaust purification performance is not impaired when the catalyst activity is improved or various regeneration controls are performed for the purpose of improving or recovering the performance of the exhaust purification system. The energy consumed for various controls, that is, the loss of fuel consumption can be minimized.

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

  FIG. 1 is a system configuration diagram showing an embodiment of a vehicle diesel engine exhaust gas purification control apparatus according to the present invention. The engine is a four-cylinder engine as an example.

  In FIG. 1, the vehicle travels with the power of the diesel engine 1.

  The output of the diesel engine 1 is transmitted from a power transmission mechanism (for example, a continuously variable transmission with an electromagnetic clutch; CVT) 51 to drive wheels 53a and 53b via a differential gear 52.

  Transmission of the output of the diesel engine 1 (CVT 51) is controlled by the CVT control unit 40.

  In order to monitor vehicle running (stop) information, the CVT control unit 40 outputs a signal from the accelerator sensor 41 (L: an output signal proportional to the amount of depression of the accelerator pedal), a signal from the start key 42 (STA: Acc position and Signal corresponding to the ON position), signal from the shift lever position sensor 43 (SFT), signal from the brake operation switch 44 (BR), signal from the vehicle speed sensor 45 (vehicle speed V), and battery charge amount for detecting the charge state of the battery 50 By inputting a signal (charge amount SOC) of the sensor 46, etc., CVT shift control suitable for the driving state of the vehicle is performed, and an engine output (required driving force for the engine) necessary for traveling of the vehicle is calculated to control the engine. A required output command (required driving force Pe) is issued to the unit 30.

  The diesel engine 1 includes an exhaust purification post-treatment device 20 that purifies the exhaust gas of the engine in the exhaust passage 3. The exhaust purification post-treatment device 20 includes a diesel particulate filter (DPF) that collects particulate matter PM in exhaust gas, and a NOx trap catalyst (LNT; Lean NOx) that adsorbs NOx when the exhaust air-fuel ratio is lean. Trap Catalyst) and an oxidation catalyst that oxidizes HC, CO (and PM) in the exhaust, and includes an exhaust purification device 22 that reduces HC, CO, PM, and NOx in the exhaust.

  DPF is a honeycomb structure made of porous ceramics, and a plurality of parallel cell spaces extending in the exhaust flow direction are adjacent to each other, one on the outlet side and the other on the inlet side, alternately with a sealing material. By sealing, the exhaust gas passes through the cell wall (its pores) and flows, and PM in the exhaust gas is collected by the cell wall.

  This DPF (particularly the surface of the cell wall facing the exhaust inflow side cell space) carries LNT and an oxidation catalyst.

  LNT adsorbs NOx in the exhaust when the exhaust air-fuel ratio is lean, and desorbs and purifies the adsorbed NOx when the exhaust air-fuel ratio is rich. As NOx adsorbents, Ba, Mg, Cs or the like is used.

  The oxidation catalyst oxidizes HC, CO (and PM) in the exhaust, and uses a noble metal such as Pt, Pd, Rh.

  Further, the exhaust purification post-treatment device 20 is a heating means for assisting the performance of the exhaust purification device 22 on the upstream side of the exhaust purification device 22, and an electric heating type for enhancing the catalyst performance in the exhaust purification post-treatment device 20. A catalyst (hereinafter referred to as EHC) 21 is disposed. The EHC 21 is obtained by carrying an oxidation catalyst or a three-way catalyst on a metal carrier that can be energized.

  A temperature sensor 35 is provided at the inlet of the exhaust purification device 22 so as to be close to the exhaust purification device 22 and the EHC 21, and the EHC temperature when the engine 1 is stopped, and the exhaust temperature during operation of the engine 1, Detect as Tex. An oxygen concentration sensor 36 for detecting the oxygen concentration O2 is provided at the outlet of the exhaust purification device 22.

  A turbocharger turbine 3a is disposed in the middle of the exhaust passage 3 (upstream from the exhaust purification post-treatment device 20), and an EGR valve 5 is provided in the EGR passage 4 branched from the upstream. The EGR valve 5 is driven by a stepping motor (not shown), and a part of the exhaust gas is recirculated to the intake pipe 2 d of the intake passage 2.

  The intake passage 2 includes, from upstream, an air cleaner 2a, a supercharger compressor 2b, an intercooler 2c, an intake throttle valve 7 that is driven to open and close by an actuator (for example, a stepping motor), and an intake pipe 2d. In the branch pipe, there is provided an intake shut-off valve 6 that independently opens and closes each branch pipe by an actuator (for example, a stepping motor).

  Here, in order to stop the inflow / outflow of the working gas in the cylinder stop control, the simplest intake shutoff valve 6 is arranged in the present embodiment. However, as a method for stopping the inflow / outflow of the working gas, Regardless, a known valve timing variable mechanism that can arbitrarily control the valve timing may be applied to the valve operating mechanism of the intake valve (and the exhaust valve).

  The fuel supply system includes a fuel tank 60 for storing diesel fuel (light oil), a fuel supply passage 16 for supplying fuel from the fuel tank 60 to the fuel injection device 10 of the engine, and a return fuel from the fuel injection device 10 of the engine. A fuel return passage 19 for returning (spill fuel) to the fuel tank 60 is provided.

  The fuel injection device 10 of the diesel engine 1 is a well-known common rail type fuel injection device, and includes a supply pump 11, a common rail (accumulation chamber) 14, and a fuel injection valve 15 provided for each cylinder. The fuel pressurized by the supply pump 11 is temporarily stored in the common rail 14 through the fuel supply passage 12 in a high pressure state, and then distributed to the fuel injection valves 15 corresponding to the number of cylinders.

  The pressure of the common rail 14 is controlled by the pressure control valve 13. That is, the pressure control valve 13 has an overflow passage 17 that returns part of the fuel discharged from the supply pump 11 to the fuel supply passage 16 via the one-way valve 18 in response to a duty signal from the engine control unit 30. By changing the flow path area, the fuel discharge amount to the common rail 14 is adjusted, and the pressure of the common rail 14 is controlled.

  The fuel injection valve 15 is an electronic injection valve that opens and closes a fuel passage to the engine combustion chamber in response to an ON-OFF signal from the engine control unit 30, and injects fuel into the combustion chamber in response to an ON signal. To stop the injection. The fuel injection amount increases as the ON signal to the fuel injection valve 15 is longer and the fuel pressure of the common rail 14 is higher.

  Further, a glow plug 24 for assisting engine start is provided facing the combustion chamber of each cylinder of the diesel engine 1.

  The engine control unit 30 communicates with the CVT control unit 40, signals from the water temperature sensor 31 (Tw), signals from the crank angle sensor 32 (engine speed and crank angle detection Ne), and signals from the cam angle sensor 33. (Cylinder discrimination signal Cyl), a signal (PCR) of the pressure sensor 34 for detecting the common rail pressure, a signal (Tex) of the temperature sensor 35, and a signal (O2) of the oxygen concentration sensor 36 are input.

  The engine control unit 30 sets the operating point of the diesel engine 1 according to the required output command (required driving force Pe) from the CVT control unit 40, for example, as shown by a to e in FIG. Take control.

  Here, the operation points of a to e in FIG. 8 and the corresponding operation region will be described.

  The engine is controlled by the engine control unit 30 so as to generate an output by following the line of points a → b → c → d → e corresponding to the signal of the accelerator sensor 41, and the CVT control unit 40 CVT shift control suitable for the driving state of the vehicle is performed.

  Point a is idling, and power is transmitted to the drive wheels 53a and 53b via the CVT 51 and the differential gear 52 in a state where the engine output exceeds the point a.

  Point b means a low output point at which sufficient catalytic activity is obtained. In the region A below this point b, the exhaust temperature flowing through the exhaust purification device is approximately 200 ° C. or lower. A temperature rise assistance is required. In addition, in order to prevent an excessive increase in the temperature of the exhaust gas purification apparatus when shifting to the deceleration state when PM regeneration is being performed, the exhaust air / fuel ratio is switched to stoichiometric or rich in this region immediately before shifting to the deceleration state.

  Point c means the best fuel consumption point. Generally, the load factor is about 80%, the rotational speed is from low to medium, and the exhaust temperature circulating through the exhaust purification device is about 400 ° C. . A region F centering on the point c means a good fuel consumption region of the engine.

  Point d means the point where the maximum output can be obtained in the fuel-efficient region F of the engine. Generally, the load factor is about 80 to 90%, the rotational speed is located at a medium speed, and the exhaust purification device is operated. About 500 ° C. is obtained as the exhaust temperature for circulation.

  The point e means the rated maximum output point of the engine, and an exhaust temperature circulating through the exhaust purification device is approximately 600 ° C. or higher.

  In the region D from the output point slightly below the point b to the point c, the exhaust temperature flowing through the exhaust purification device is approximately 200 to 400 ° C. Therefore, if the temperature is slightly increased, the temperature is suitable for NOx regeneration. However, it is necessary to increase the temperature raising assistance for PM regeneration.

  The region C from the output point slightly below the point b to the point d is a region where high NOx adsorption activity is obtained because the exhaust temperature flowing through the exhaust purification device is approximately 200 to 500 ° C.

  In the region E from the point c to the point e, the exhaust temperature flowing through the exhaust purification device is approximately 400 to 600 ° C., so the PM collected in the exhaust purification device is self-regenerated. That is, it is a temperature region suitable for PM regeneration.

  And the area | region B containing the said area | regions C, D, and E is an area | region from which the high oxidation activity is acquired since the exhaust temperature which distribute | circulates an exhaust gas purification device is obtained about 200-600 degreeC. Further, in order to perform S poisoning regeneration, it is necessary to perform temperature increase assistance throughout this region.

  The exhaust purification control apparatus of the present invention is controlled by the engine control unit 30, which will be described with reference to the flowcharts of FIGS.

  FIG. 9 shows a main routine (basic control routine) related to the exhaust purification control of the present invention, and FIGS. 10 to 14 show a subroutine related to the exhaust purification control of the present invention.

  In the main routine of the exhaust gas purification control of the present invention of FIG. 9, in step 100, the signal (L) of the accelerator sensor 41, the signal (STA) of the start key 42, the signal (SFT) of the shift lever position sensor 43, the brake operation switch 44 signal (BR), vehicle speed sensor 45 signal (V), battery charge amount sensor 46 signal (SOC), water temperature sensor 31 signal (Tw), crank angle sensor 32 signal (engine speed and Crank angle detection Ne), cam angle sensor 33 signal (cylinder discrimination signal Cyl), pressure sensor 34 signal (PCR) for detecting common rail pressure, temperature sensor 35 signal (Tex) for detecting exhaust gas temperature or EHC temperature, The signal (O 2) of the oxygen concentration sensor 36 is read and the process proceeds to step 200.

  In step 200, energization control of the EHC 21 is performed in accordance with a subroutine shown in FIG.

  In step 101, it is determined by the S poisoning regeneration timing determination in step 110 described later that the S poison regeneration of the exhaust purification device 22 is necessary, and it is determined whether the S poison regeneration command flag is ON.

  If Yes in step 101 and the S poison regeneration of the exhaust purification device 22 is necessary, the process proceeds to step 1000.

  In step 1000, the cylinder control and the exhaust air / fuel ratio control for the S poison regeneration control of the exhaust purification device 22 are continued or started in accordance with a subroutine shown in FIG.

  Then, the routine proceeds to step 104, where it is determined whether the S poisoning regeneration of the exhaust purification device 22 has been completed (for example, a predetermined time has elapsed). If the answer is No in step 104 and the S poisoning regeneration of the exhaust gas purification device 22 has not ended, the process returns. If the answer is Yes and the S poisoning regeneration ends, the process proceeds to step 140 and the S poisoning regeneration end process is completed. After performing (for example, regeneration command flag OFF, regeneration time counter reset), the process returns.

  If No in step 101 and S poisoning regeneration is not necessary, the process proceeds to step 102.

  In step 102, it is determined that PM regeneration of the exhaust purification device 22 is necessary by PM regeneration timing determination in step 120 described later, and it is determined whether the PM regeneration command flag is ON.

  If YES in step 102 and PM regeneration of the exhaust purification device 22 is necessary, the process proceeds to step 2000.

  In step 2000, the cylinder control and the exhaust air / fuel ratio control for PM regeneration control of the exhaust purification device 22 are continued or started in accordance with a subroutine shown in FIG.

  Then, the routine proceeds to step 105, where it is determined whether PM regeneration of the exhaust purification device 22 has ended (for example, a predetermined time has elapsed). If NO in step 105 and PM regeneration has not ended, the process returns, and if it is Yes and PM regeneration has ended, the process proceeds to step 150 and PM regeneration end processing (for example, regeneration command flag OFF, regeneration time counter reset) ) To return.

  If No in step 102 and PM regeneration is not necessary, the process proceeds to step 103.

  In step 103, it is determined that NOx regeneration of the exhaust purification device 22 is necessary by NOx regeneration timing determination in step 130 described later, and it is determined whether the NOx regeneration command flag is ON.

  If YES in step 103 and NOx regeneration of the exhaust purification device 22 is necessary, the process proceeds to step 3000.

  In step 3000, cylinder control and exhaust air-fuel ratio control for NOx regeneration control of the exhaust purification device 22 are continued or started in accordance with a subroutine shown in FIG.

  Then, the routine proceeds to step 106, where it is determined whether NOx regeneration of the exhaust purification device 22 has been completed (for example, a predetermined time has elapsed). If NO in step 106 and NOx regeneration is not completed, the process returns. If NO and NOx regeneration is terminated, the process proceeds to step 160, where NOx regeneration end processing (for example, regeneration command flag OFF, regeneration time counter reset). ) To return.

  If NO in step 103 and NOx regeneration is not necessary, the process proceeds to step 110.

  In step 110, the sulfur poisoning regeneration time determination of the exhaust purification device 22 is performed. Here, the S poisoning regeneration timing determination is performed by searching from predetermined data stored in the ROM of the control unit 30 in advance using, for example, the engine rotational speed Ne and the fuel injection amount Qmain as parameters, and purifying exhaust gas per unit time. The amount of S poisoning of the device 22 is obtained, integrated, and it is determined whether or not the accumulated amount of S poisoning exceeds a predetermined S poisoning limit amount. It is possible to determine whether this is a necessary time.

  After performing the S poisoning regeneration time determination in step 110, the process proceeds to step 120.

  In step 120, the PM regeneration timing of the exhaust purification device 22 is determined. Here, the PM regeneration timing determination is performed by searching from predetermined data stored in the ROM of the control unit 30 in advance using, for example, the engine rotational speed Ne and the fuel injection amount Qmain as parameters, and the exhaust purification device 22 per unit time. PM regeneration amount (deposition amount) is obtained, and this is integrated, and PM regeneration is determined by determining whether the integrated PM collection amount exceeds a predetermined collection limit amount (PM oxidation combustion removal) It is possible to determine whether this is a necessary time.

  After determining the PM regeneration time in step 120, the process proceeds to step 130.

  In step 130, the NOx regeneration timing of the exhaust purification device 22 is determined. Here, the NOx regeneration timing determination is performed by searching from predetermined data stored in the ROM of the control unit 30 in advance using, for example, the engine rotational speed Ne and the fuel injection amount Qmain as parameters, and the exhaust purification device 22 per unit time. This is the time when NOx regeneration (NOx desorption reduction purification) is necessary by determining the NOx adsorption amount of the NOx, integrating the NOx adsorption amount, and determining whether the accumulated NOx adsorption amount exceeds a predetermined adsorption limit amount. Can be determined.

  After determining the NOx regeneration time in step 130, the process proceeds to step 4000.

  In step 4000, the catalyst activity improvement control is performed according to the subroutine shown in FIG.

  FIG. 10 is a flowchart showing a subroutine for performing cylinder control and exhaust air-fuel ratio control for S poisoning regeneration control (stoichiometric combustion control) of the exhaust purification device 22 performed in step 1000 (FIG. 9). . As described above, the engine is a four-cylinder engine.

  In the S poisoning regeneration control routine of FIG. 10, in step 1010, the vehicle is in an engine brake state (for example, the clutch is engaged and the output of the accelerator sensor is 0, and the engine speed is equal to or higher than the idle speed or the vehicle speed is 0). Or more).

  If YES in step 1010 and the engine is in the brake state, the process proceeds to step 1150, where the intake shutoff valves 6 of all the cylinders are closed to stop the inflow / outflow of the working gas, and at the same time, the fuel injection valve 15 is turned OFF to inject fuel. Stop and return.

  If No in Step 1010, the process proceeds to Step 1020, and the required driving force (each cylinder output when performing all-cylinder operation) Pe is set as a switching condition between one-cylinder stop operation (three-cylinder operation) and all-cylinder operation. It is determined whether it falls below PE5, and if No (when Pe> PE5), the process proceeds to step 1040, where S-poisoning regeneration pattern 0 is selected and all cylinder operation is selected and each cylinder output (cylinder control target) Pe ′ is set. And go to Step 1070.

  If YES in step 1020, the process proceeds to step 1030, and it is determined whether the required driving force Pe exceeds PE4 set as the switching condition between the two-cylinder stop operation (two-cylinder operation) and the one-cylinder stop operation (three-cylinder operation). If Yes (in the case of PE5> Pe> PE4), the process proceeds to step 1050 to select one-cylinder stop operation (three-cylinder operation) as the S poisoning regeneration pattern 1 to obtain each cylinder output Pe ′. Proceed to 1070.

  If No in Step 1030 (when Pe <PE4), the process proceeds to Step 1060, where the two-cylinder stop operation (two-cylinder operation) is selected as the S poisoning regeneration pattern 2 to obtain each cylinder output Pe ′. Proceed to 1070.

  Here, the required driving force, that is, each cylinder output Pe during all-cylinder operation, is roughly necessary for the amount of depression of the accelerator pedal (accelerator sensor output L) of the driver, that is, the vehicle travel that is determined by the driver by the accelerator operation. As the driving force, it is obtained from predetermined data stored in the ROM of the control unit 30 in advance. The cylinder outputs Pe during the all-cylinder operation and the cylinder outputs Pe ′ during the cylinder stop operation are shown in FIGS. As shown in FIG.

During all cylinder operation: Pe '= Pe
Single cylinder stop operation: Pe ′ = 4 × Pe ÷ 3
2-cylinder stop operation: Pe ′ = 4 × Pe / 2
That is, the output of each working cylinder is determined so that the sum of the outputs of each working cylinder during cylinder stop operation is equal to the sum of the outputs of each cylinder during all cylinder operation (4 × Pe).

  Regarding the setting of PE4 and PE5, as shown in FIGS. 5 and 7, each cylinder output Pe ′ in the two-cylinder stop operation (two-cylinder operation) is used for PE4, and one cylinder stop operation (three-cylinder operation) is used for PE5. ) Is set so as not to exceed PE2 ′ (point d) at which the maximum output is obtained in the fuel efficiency range F of the engine. In other words, as shown in FIG. 7, the number of stopped cylinders is determined so that the output Pe ′ of each working cylinder during cylinder stop operation does not exceed a predetermined value (PE2 ′). Accordingly, when performing the S poisoning regeneration, in addition to the SV reduction effect by increasing the exhaust temperature by stopping the cylinder and reducing the exhaust inflow amount to the exhaust purification device, the frequency of operation in the fuel-efficient region F is determined. Can be high. For this reason, it is possible to minimize the loss of fuel consumption spent on the S poisoning regeneration control.

  In step 1070, predetermined data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is searched, and the main injection amount Qmain and the main injection timing ITmain for performing the main injection control of the working cylinder are obtained. The process proceeds to step 1080.

  In step 1080, predetermined data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and post injection for the purpose of S poison regeneration (the main fuel for generating the drive output). In order to perform the fuel injection performed in the expansion stroke or the exhaust stroke after the injection), the post injection amount Qpost and the post injection timing ITpost are obtained, and the process proceeds to Step 1090.

In step 1090, in addition to exhaust control, an EGR target value (drive signal for the EGR valve 5) for the purpose of S poison regeneration is obtained, and the process proceeds to step 1100.
In step 1100, in addition to exhaust control, an intake throttle target value (drive signal for the intake throttle valve 7) for the purpose of S poison regeneration is obtained, and the routine proceeds to step 1110.

  Here, in the S poisoning regeneration, it is necessary to keep the exhaust gas temperature flowing into the exhaust gas purification apparatus at 600 ° C. or higher with the exhaust air / fuel ratio being stoichiometric over a wide engine output range.

  For this reason, for example, as shown in FIG. 3, it is desirable to perform control depending on the post injection for the enrichment of the exhaust gas and the temperature rise, and the post injection range is performed in the whole range of Pe = a to e. EGR enhancement to be performed in addition to the exhaust control is in the range of Pe = a to PE2 (Pe ′ = a to b), and the intake throttle enhancement is stopped in the range of Pe = a to b points (Pe ′ = ac). It is good.

  In step 1110, based on the data obtained in steps 1070 and 1080, main injection for engine output control and post injection for temperature rise and exhaust enrichment control for the purpose of S poison regeneration are performed. That is, common rail pressure control and fuel injection valve drive control are performed, and the process proceeds to step 1120.

  In step 1120, based on the drive signal obtained in step 1090, the EGR valve 5 is driven and controlled, and in addition to exhaust control, EGR control is performed for temperature increase and exhaust enrichment for the purpose of S poison regeneration. Proceed to 1130.

  In step 1130, based on the drive signal obtained in step 1100, the intake throttle valve 7 is driven and controlled, and in addition to exhaust control, intake throttle control for temperature increase and exhaust enrichment for the purpose of S poison regeneration is performed. Then go to step 1140.

  In Step 1140, based on the data obtained in Step 1040, Step 1050, or Step 1060, the operation of the predetermined cylinder is stopped, and a return is made.

  FIG. 11 is a flowchart showing a subroutine for performing cylinder control and exhaust air-fuel ratio control for PM regeneration control of the exhaust purification device 22 performed in step 2000 (FIG. 9) described above.

  In the PM regeneration control routine of FIG. 11, in step 2010, it is determined whether the vehicle is in an engine brake state.

  If YES in step 2010 and the engine is in an engine brake state, the process proceeds to step 2200 where the intake shutoff valves 6 of all the cylinders are closed to stop the inflow / outflow of the working gas, and at the same time the fuel injection valve 15 is turned OFF to inject fuel Stop and return.

  If No in step 2010, the process proceeds to step 2020, where it is determined whether the required driving force Pe is less than PE5 set as the switching condition between the one-cylinder stop operation (three-cylinder operation) and the all-cylinder operation. (When Pe> Pe5), the process proceeds to step 2040 where all cylinder operation is selected as the PM regeneration pattern 0 to obtain each cylinder output Pe ′, and the process proceeds to step 2080.

  If YES in step 2020, the process proceeds to step 2030, and it is determined whether the required driving force Pe exceeds PE4 set as the switching condition between the two-cylinder stop operation (two-cylinder operation) and the one-cylinder stop operation (three-cylinder operation). If Yes (PE5> Pe> Pe4), the process proceeds to Step 2050, where the 1-cylinder stop operation (3-cylinder operation) is selected as the PM regeneration pattern 1, and each cylinder output Pe 'is obtained. move on.

  If No in Step 2030 (Pe <PE4), the process proceeds to Step 2060, where the two-cylinder stop operation (two-cylinder operation) is selected as the PM regeneration pattern 2 to obtain each cylinder output Pe ′. move on.

  Here, as shown in FIGS. 5 and 7, in the PM regeneration, as in the S poisoning regeneration, each cylinder output Pe ′ in the two-cylinder stop operation (two-cylinder operation) is the PE4, and one cylinder is stopped in the PE5. Each cylinder output Pe ′ in operation (three-cylinder operation) is set so as not to exceed PE2 ′ (point d) at which the maximum output is obtained in the good fuel consumption region F of the engine. Therefore, in addition to the SV reduction effect by increasing the exhaust temperature by stopping the cylinder and reducing the exhaust inflow amount to the exhaust purification device, it is possible to increase the frequency of operation in the fuel-efficient region F. For this reason, the loss of fuel consumption spent on PM regeneration control can be minimized.

  In Step 2070, it is determined whether the required driving force Pe is less than PE1 set as the PM regeneration suspension switching condition. If Yes, the process proceeds to Step 2120. If No, the process proceeds to Step 2080.

  In step 2120, predetermined data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and the main injection amount Qmain and the main injection timing ITmain for performing the main injection control of the working cylinder are obtained. Then, go to Step 2130.

  In step 2130, predetermined data set in advance corresponding to the rotational speed Ne and the working cylinder output Pe ′ is retrieved, and post injection amount Qpost and post injection are performed in order to perform post injection for the purpose of holding PM regeneration. The process proceeds to step 2140 after obtaining the time ITpost.

  In step 2140, an EGR target value (drive signal for the EGR valve 5) for exhaust control and PM regeneration suspension is obtained, and the process proceeds to step 2150.

  In step 2150, an intake throttle target value (drive signal for the intake throttle valve 7) for exhaust control and PM regeneration suspension is obtained, and the process proceeds to step 2160.

  Here, in the PM regeneration suspension, when the temperature of the exhaust purification device becomes equal to or higher than the oxidation reaction temperature (400 ° C.) of PM during PM regeneration, the vehicle shifts to a deceleration state and the oxygen concentration rapidly increases ( Since the fuel injection device of the diesel engine is cut when decelerating, the oxygen concentration approaches 21% of the atmospheric concentration), which prevents PM from reburning in an instant and burning the exhaust purification device due to overheating. To do. Therefore, the air-fuel ratio of the exhaust gas in the cylinder is switched to stoichiometric in the operation region of PE1 or less immediately before the shift to the deceleration state to prepare for the shift to the deceleration state.

  Therefore, for example, as shown in FIG. 2, post injection performed for the purpose of holding PM regeneration, and EGR strengthening and intake throttle strengthening performed for the purpose of exhaust control and PM regeneration suspension are performed in the range of Pe = a to Pe1. Do.

  In step 2080, predetermined table data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and the main injection amount Qmain and the main injection timing ITmain for performing the main injection control of the working cylinder. To step 2090.

  In step 2090, predetermined table data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and post injection for exhaust gas temperature increase for the purpose of PM regeneration is performed. The injection amount Qpost and the post injection timing ITpost are obtained, and the process proceeds to step 2100.

  In step 2100, an EGR target value (driving signal for the EGR valve 5) mainly for exhaust control is obtained, and the process proceeds to step 2110.

  In step 2110, an intake throttle target value (drive signal for the intake throttle valve 7) whose main purpose is exhaust control is obtained, and the process proceeds to step 2160.

  Here, in PM regeneration, it is necessary to maintain the exhaust air / fuel ratio lean in a wide engine output range and to keep the exhaust temperature flowing into the exhaust purification device at 400 ° C. or higher.

  For this reason, for example, as shown in FIG. 2, in order to raise the temperature while keeping the exhaust air-fuel ratio lean, it is desirable to perform control that depends on post-injection, and in post-injection, Pe = Pe1 to b (Pe ′ = In the range of c), the range in which Pe ′ exceeds c is the PM self-regeneration region, so post injection is stopped. Further, it is preferable to stop the EGR and the intake throttle to the level of the normal exhaust control.

  In Step 2160, based on the data obtained in Step 2080, 2090, or Steps 2120 and 2130, the main injection for engine output control and the post for the purpose of PM regeneration (lean) or PM regeneration suspension (stoichi) Perform the injection. That is, common rail pressure control and fuel injection valve drive control are performed, and the routine proceeds to step 2170.

  In step 2170, the EGR valve 5 is driven and controlled based on the drive signal obtained in step 2100 or 2140, EGR control for the purpose of PM regeneration or PM regeneration suspension is performed in addition to exhaust control, and the process proceeds to step 2180.

  In step 2180, the intake throttle valve 7 is driven and controlled based on the drive signal obtained in step 2110 or step 2150, and in addition to exhaust control, intake throttle control for the purpose of PM regeneration or PM regeneration suspension is performed. move on.

  In step 2190, the operation of the predetermined cylinder is stopped based on the data obtained in step 2040, step 2050, or step 2060, and the process returns.

  FIG. 12 is a flowchart showing a subroutine for performing cylinder control and exhaust air-fuel ratio control for NOx regeneration control (rich combustion control) of the exhaust purification device 22 performed in step 3000 (FIG. 9) described above.

  In the NOx regeneration control routine of FIG. 12, in step 3010, it is determined whether the vehicle is in an engine brake state.

  If YES in step 3010 and the engine is in the brake state, the process proceeds to step 3150, where the intake shutoff valves 6 of all the cylinders are closed to stop the inflow / outflow of the working gas, and at the same time, the fuel injection valve 15 is turned OFF to inject fuel. Stop and return.

  If NO in step 3010, the process proceeds to step 3020, where it is determined whether the required driving force Pe falls below PE3 set as the switching condition between the one-cylinder stop operation (three-cylinder operation) and the all-cylinder operation. (In the case of Pe> PE3), the process proceeds to step 3040, the all cylinder operation is selected as the NOx regeneration pattern 0 to obtain each cylinder output Pe ′, and the process proceeds to step 3070.

  If YES in step 3020, the process proceeds to step 3030 to determine whether the required driving force Pe exceeds PE2 set as the switching condition between the two-cylinder stop operation (two-cylinder operation) and the one-cylinder stop operation (three-cylinder operation). If Yes (in the case of PE3> Pe> PE2), the process proceeds to step 3050, where the one-cylinder stop operation (three-cylinder operation) is selected as the NOx regeneration pattern 1 to obtain each cylinder output Pe ′. move on.

  If No in Step 3030 (when Pe <PE2), the process proceeds to Step 3060, where the two-cylinder stop operation (two-cylinder operation) is selected as the NOx regeneration pattern 2 to obtain each cylinder output Pe ′. move on.

  Here, regarding the setting of PE2 and PE3, as shown in FIGS. 4 and 6, each cylinder output Pe ′ in the two-cylinder stop operation (two-cylinder operation) is PE2, and PE3 is the one-cylinder stop operation (three-cylinder stop operation). Each cylinder output Pe ′ in (operation) is set so as not to exceed a low output point PE1 ′ (point b) at which sufficient catalytic activity is obtained. For this reason, NOx regeneration is most effective when it is controlled to be rich (λ ≦ 0.8) in the range of about 250 to 450 ° C. Conversely, if cylinder control such as S-poisoning regeneration or PM regeneration is performed and the output of each cylinder becomes relatively high to increase the temperature rise effect, the NOx regeneration efficiency decreases. In the case of NOx regeneration, the temperature control request is not as strong as in S poison regeneration or PM regeneration, and therefore it is appropriate to perform cylinder control at a low output portion.

  In step 3070, predetermined data set in advance corresponding to the rotational speed Ne and the working cylinder output Pe ′ is retrieved, and the main injection amount Qmain and the main injection timing ITmain for performing the main injection control of the working cylinder are obtained. Then, go to step 3080.

  In step 3080, predetermined data preset in correspondence with the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and the post injection amount Qpost and the post injection timing are executed in order to perform post injection for the purpose of NOx regeneration. Obtain ITpost and go to step 3090.

  In step 3090, an EGR target value (drive signal for the EGR valve 5) for the purpose of NOx regeneration is obtained in addition to exhaust control, and the process proceeds to step 3100.

  In step 3100, in addition to exhaust control, an intake throttle target value (drive signal for the intake throttle valve 7) for NOx regeneration is obtained, and the routine proceeds to step 3110.

  Here, as described above, NOx regeneration is most effective when the exhaust air-fuel ratio is made rich (λ ≦ 0.8) and the exhaust temperature flowing into the exhaust purification device is controlled to 250 to 450 ° C. The rich spike for NOx regeneration is completed in a short time of about several seconds.

  For this reason, for example, as shown in FIG. 3, the range of post injection, intake throttle strengthening, and EGR strengthening performed for exhaust enrichment and temperature rise corresponds to the aforementioned load range where the NOx regeneration effect is high and is low. It is desirable to perform post injection and intake throttle strengthening in the range of Pe = a to c, and EGR strengthening in the range of Pe = a to b, so as to enhance the output portion enrichment and the temperature rise effect.

  In step 3110, based on the data obtained in steps 3070 and 3080, main injection for engine output control and post-injection for the purpose of NOx regeneration are performed. That is, common rail pressure control and fuel injection valve drive control are performed, and the routine proceeds to step 3120.

  In step 3120, the EGR valve 5 is drive-controlled based on the drive signal obtained in step 3090, EGR control for NOx regeneration is performed in addition to exhaust control, and the process proceeds to step 3130.

  In step 3130, the intake throttle valve 7 is driven and controlled based on the drive signal obtained in step 3100, intake throttle control for NOx regeneration is performed in addition to exhaust control, and the process proceeds to step 3140.

  In step 3140, the operation of the predetermined cylinder is stopped based on the data obtained in step 3040, 3050, or 3060, and the process returns.

  FIG. 13 is a flowchart showing a subroutine for performing cylinder control and exhaust air-fuel ratio control for catalyst activity improvement control of the exhaust purification device 22 performed in the above-described step 4000 (FIG. 9).

  In the catalyst activity improvement control routine of FIG. 13, in step 4010, it is determined whether the vehicle is in an engine brake state.

  If YES in step 4010 and the engine is in the brake state, the process proceeds to step 4200, the intake shutoff valves 6 of all the cylinders are closed to stop the inflow / outflow of the working gas, and at the same time, the fuel injection valve 15 is turned OFF to inject fuel. Stop and return.

  If No in Step 4010, the process proceeds to Step 4020, where it is determined whether the required driving force Pe is less than PE3 set as the switching condition between the one-cylinder stop operation (three-cylinder operation) and the all-cylinder operation. (In the case of Pe> PE3), the process proceeds to step 4040, the all cylinder operation is selected as the catalyst activity improvement pattern 0, each cylinder output Pe ′ is obtained, and the process proceeds to step 4090.

  If YES in step 4020, the process proceeds to step 4030 to determine whether the required driving force Pe exceeds PE2 set as the switching condition between the two-cylinder stop operation (two-cylinder operation) and the one-cylinder stop operation (three-cylinder operation). If Yes (PE3> Pe> PE2), the process proceeds to Step 4050, where one-cylinder stop operation (three-cylinder operation) is selected as the catalyst activity improvement pattern 1 to obtain each cylinder output Pe ′. Proceed to

  If No in Step 4030 (when Pe <PE2), the process proceeds to Step 4060, where the two-cylinder stop operation (two-cylinder operation) is selected as the catalyst activity improvement pattern 2 to obtain each cylinder output Pe ′. Proceed to

  Here, as shown in FIGS. 4 and 6, also in the improvement of the catalyst activity, as in NOx regeneration, PE2 has each cylinder output Pe ′ in two-cylinder stop operation (two-cylinder operation), and PE3 has one-cylinder stop operation. Each cylinder output Pe ′ in (3-cylinder operation) is set so as not to exceed a low output point PE1 ′ (point b) at which sufficient catalytic activity is obtained. This is because the catalyst has sufficient activity at about 200 ° C. or higher. In other words, although there is a difference in exhaust air-fuel ratio requirements between catalyst activity improvement (lean) and NOx regeneration (rich), it is appropriate that the cylinder control is performed at a low output portion because the temperature increase request is not strong.

  In Step 4070, it is determined whether the required driving force Pe is less than PE1 set as the switching condition for enhancement of catalyst activity. If Yes, the process proceeds to Step 4080, and if No, the process proceeds to Step 4090.

  In step 4080, it is determined whether the exhaust temperature Tex is lower than a predetermined temperature Tex1 (eg, 200 ° C.) at which sufficient catalytic activity is obtained. If Yes, the process proceeds to step 4120, and if No, the process proceeds to step 4090.

  In step 4120, predetermined data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and the main injection amount Qmain and the main injection timing ITmain for performing the main injection control of the working cylinder are obtained. The process proceeds to step 4130.

  In step 4130, predetermined data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and the post injection amount Qpost and the post injection are performed in order to perform the post injection for the purpose of improving the catalyst activity. Time ITpost is obtained and the process proceeds to step 4140.

  In step 4140, an EGR target value (drive signal for the EGR valve 5) for the purpose of improving the catalyst activity is obtained, and the process proceeds to step 4150.

  In step 4150, an intake throttle target value (drive signal for the intake throttle valve 7) for the purpose of improving the catalyst activity is obtained, and the process proceeds to step 4160.

  In step 4090, predetermined table data set in advance corresponding to the rotational speed Ne and the output Pe ′ of the working cylinder is retrieved, and the main injection amount Qmain and the main injection timing ITmain for performing the main injection control of the working cylinder. To step 4100.

  In step 4100, an EGR target value (driving signal for the EGR valve 5) whose main purpose is the reference exhaust control is obtained, and the process proceeds to step 4110.

  In step 4110, an intake throttle target value (drive signal for the intake throttle valve 7) whose main purpose is reference exhaust control is obtained, and the process proceeds to step 4160.

  Here, the catalyst activity may be improved under temperature conditions where catalyst activity cannot be obtained. For example, as shown in FIG. 2, while maintaining the exhaust air-fuel ratio lean, the post-injection, EGR, and intake throttle Strengthening is performed within a range of Pe = Pe1 or less.

  In step 4160, based on the data obtained in step 4120, 4130, or step 4090, main injection for engine output control and post-injection for the purpose of improving catalyst activity are performed as necessary. That is, common rail pressure control and fuel injection valve drive control are performed, and the routine proceeds to step 4170.

  In step 4170, based on the drive signal obtained in step 4140 or step 4100, the EGR valve 5 is driven and controlled, and in addition to exhaust control, EGR control is performed for the purpose of improving the catalyst activity, and the process proceeds to step 4180.

  In step 4180, the intake throttle valve 7 is driven and controlled based on the drive signal obtained in step 4150 or step 4110, intake throttle control is performed for the purpose of improving catalyst activity in addition to exhaust control, and the process proceeds to step 4190.

  In step 4190, the operation of the predetermined cylinder is stopped based on the data obtained in step 4040, step 4050, or step 4060, and the process returns.

  FIG. 14 is a flowchart showing a subroutine for EHC energization control performed for assisting catalyst activity in step 200 (FIG. 9).

  In the EHC energization control routine of FIG. 14, in step 210, it is determined whether or not the charge amount SOC of the battery 50 is below a predetermined reference value SOC <b> 1 indicating a sufficient capacity.

  In step 220, it is determined whether the exhaust temperature (or EHC temperature) Tex exceeds a predetermined temperature Tex1 that is a catalyst activation temperature.

  If YES in either step 210 or 220, that is, if the remaining battery level (charge amount) is insufficient or if catalyst heating is unnecessary at a high temperature, the routine proceeds to step 230 and the EHC 21 is energized. Stop and return.

  If both Steps 210 and 220 are No, that is, if the remaining battery level (charge amount) is sufficient and catalyst heating is required at a low temperature, the process proceeds to Step 240 to energize the EHC 21 and return. It becomes.

  As has been described above, the present invention can improve catalyst activity and control various regenerations for the purpose of improving and recovering the performance of an exhaust purification device in a vehicle using a diesel engine provided with an exhaust purification device in an exhaust passage. When performing, depending on the state of the exhaust purification device and the required driving force required for vehicle travel, the number of stop cylinders of the diesel engine, the output (load) of the working cylinder, and the air-fuel ratio of the exhaust flowing into the exhaust purification device are determined. Since the control is appropriately performed, the energy consumed for various controls, that is, the loss of fuel consumption can be minimized without impairing the exhaust purification performance.

  The cylinder control means determines the output of each working cylinder so that the sum of the outputs of each working cylinder during the cylinder stop operation becomes equal to the sum of the outputs of each cylinder during the all cylinder operation. The number of stopped cylinders is determined so that the output of each working cylinder does not exceed a predetermined value (PE2 ′ in FIG. 7 or PE1 ′ in FIG. 6).

  Here, the predetermined value is changed depending on whether it is a catalyst activity improvement request, a NOx regeneration request, a PM regeneration request, or an S poisoning regeneration request, and is set to a low load side when a catalyst activity improvement request or a NOx regeneration request is made. In contrast to the setting (PE1 ′ in FIG. 6), it is set to the high load side at the time of PM regeneration request or S poisoning regeneration request (PE2 ′ in FIG. 7). Thereby, the operation frequency in the region suitable for each request can be increased.

  The cylinder control means decreases the number of stopped cylinders as the required driving force increases, but even if the required driving force is constant, the PM regeneration request is made based on the number of stopped cylinders when the catalyst activity improvement request or the NOx regeneration request is made. The number of stopped cylinders is increased at the time of S or S poisoning regeneration request.

  The exhaust air / fuel ratio control means keeps the exhaust air / fuel ratio of the working cylinder lean when the catalyst activity improvement request is made. When NOx regeneration is requested, the exhaust air-fuel ratio of the working cylinder is enriched. When PM regeneration is requested, the exhaust air-fuel ratio of the working cylinder is kept lean. However, if the required driving force falls below a predetermined value (PE1) when PM regeneration is requested, the exhaust air-fuel ratio of the working cylinder is controlled to stoichiometric. When the S poisoning regeneration request is made, the exhaust air-fuel ratio of the working cylinder is controlled to be stoichiometric or rich.

  The cylinder control means stops all the cylinders when it is in a decelerating state when a catalyst activity improvement request, a NOx regeneration request, a PM regeneration request, or an S poisoning regeneration request is made.

  Cylinder stop determined in advance by the cylinder control means and the air-fuel ratio control means when the catalyst activity improvement request of the exhaust gas purification device, the PM regeneration request, the NOx regeneration request, or the S poisoning regeneration request When the vehicle shifts to a deceleration state when the control and the exhaust air-fuel ratio control are being performed, the control is performed in detail as follows.

  If NOx regeneration control or S poisoning regeneration control is being performed, the air-fuel ratio of the exhaust gas in the cylinder is kept stoichiometric or rich, and the inflow of exhaust gas to the exhaust gas purification device is stopped.

  If PM regeneration control is being performed, the flow of exhaust gas into the exhaust purification device is stopped after the air-fuel ratio of the exhaust gas in the cylinder is switched to stoichiometric or rich immediately before shifting to the deceleration state.

  If the catalyst activity improvement control is being performed, the air-fuel ratio of the exhaust gas in the cylinder is kept lean, and the inflow of exhaust gas to the exhaust purification device is stopped.

  As described above, when the vehicle shifts to the deceleration state when the above various controls are performed, the air-fuel ratio of the exhaust gas in the cylinder is kept lean, stoichiometric or rich, or from lean to stoichiometric or rich. After selecting the optimal exhaust state to switch, the exhaust purification device is overheated or decooled during the deceleration state to stop the inflow of exhaust gas to the exhaust purification device Nor. For this reason, since the control state can be promptly restored when the deceleration state is released, the time required for the catalyst activity improvement and the regeneration process is not prolonged, and this can also reduce the loss of fuel consumption.

  The exhaust air / fuel ratio control means selects at least one of post-injection, intake throttle enhancement, and EGR enhancement performed in the expansion stroke or exhaust stroke after the main injection of fuel for generating a drive output for the working cylinder Thus, the air-fuel ratio of the exhaust gas discharged from the working cylinder and flowing into the exhaust purification device is controlled.

  Here, when the exhaust air / fuel ratio control means controls the exhaust air / fuel ratio by post-injection, the upper limit of the required driving force permitting post-injection is as follows: catalyst activity improvement request, PM regeneration request, NOx regeneration request, In order of the poisoning regeneration request, the highest is set when the S poison regeneration request is made (FIGS. 2 and 3).

  Further, when the exhaust air / fuel ratio control means controls the exhaust air / fuel ratio by strengthening the intake throttle, the upper limit of the required driving force for permitting the intake throttle enhancement is as follows: catalyst activation improvement request, PM regeneration request, S poison regeneration regeneration request When the NOx regeneration is requested, the highest value is set in the order of when the NOx regeneration is requested (FIGS. 2 and 3).

  Further, when the air-fuel ratio control means controls the exhaust air-fuel ratio by EGR enhancement, the upper limit of the required driving force that permits EGR enhancement is as follows: catalyst activation improvement request, PM regeneration request, S poisoning regeneration request, NOx In order of the regeneration request, the highest is set when the NOx regeneration is requested (FIGS. 2 and 3).

The system block diagram which shows one Embodiment of the exhaust gas purification control apparatus of this invention The figure which shows each control system of catalyst activity improvement control and PM regeneration control The figure which shows each control system of NOx reproduction | regeneration control and S poison reproduction | regeneration control Cylinder control pattern diagram for catalyst activity improvement and NOx regeneration Pattern diagram of cylinder control for PM regeneration and S poison regeneration Output characteristic diagram of cylinder control for catalyst activity improvement and NOx regeneration Output characteristics diagram of cylinder control for PM regeneration and S poison regeneration Characteristic diagram showing operating range Flowchart showing main routine of exhaust purification control Flow chart of S poisoning regeneration control routine Flow chart of PM regeneration control routine NOx regeneration control routine flowchart Flow chart of catalyst activity improvement control routine EHC energization control routine flowchart

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Intake passage 2a Air cleaner 2b Supercharger compressor 2c Intercooler 2d Intake pipe 3 Exhaust passage 3a Turbocharger turbine 4 EGR passage 5 EGR valve 6 Intake shut-off valve 7 Intake throttle valve 10 Fuel injection device 11 Supply pump 12 Fuel supply passage 13 Pressure control valve 14 Common rail (accumulation chamber)
15 Fuel injection valve 16 Fuel supply passage 17 Overflow passage 18 One-way valve 19 Fuel return passage 20 Exhaust purification post-treatment device 21 EHC
21 Exhaust gas purification device (DPF + NOx trap catalyst + oxidation catalyst)
24 Glow plug 30 Engine control unit 31 Water temperature sensor 32 Crank angle sensor 33 Cam angle sensor 34 Pressure sensor 35 Temperature sensor 36 Oxygen concentration sensor 40 CVT control unit 41 Accelerator sensor 42 Start key 43 Shift lever position sensor 44 Brake operation switch 45 Vehicle speed sensor 46 Battery charge sensor 50 Battery 51 Power transmission mechanism (CVT with electromagnetic clutch)
52 Differential gear 53a, 53b Drive wheel 60 Fuel tank

Claims (17)

A filter that is disposed in the exhaust passage and collects PM in the exhaust, NOx that adsorbs NOx in the exhaust when the exhaust air-fuel ratio is lean, and NOx that desorbs and reduces the adsorbed NOx when the exhaust air-fuel ratio is rich An exhaust purification device having a trap catalyst and an oxidation catalyst for oxidizing HC and CO in the exhaust;
An exhaust purification device request detecting means for detecting a request for an exhaust temperature or an exhaust air-fuel ratio based on a state of the exhaust purification device;
Required driving force detecting means for detecting required driving force for the internal combustion engine;
By stopping the gas inflow and outflow and fuel supply in each cylinder of the internal combustion engine, some cylinders can be stopped, the exhaust temperature or exhaust air-fuel ratio request based on the state of the exhaust purification device, the internal combustion engine Cylinder control means for determining and controlling the number of stopped cylinders and the output of the working cylinder according to the required driving force for the engine,
Exhaust gas for controlling the air-fuel ratio of the exhaust gas discharged from the working cylinder and flowing into the exhaust gas purification device in accordance with the request for the exhaust gas temperature or the exhaust air-fuel ratio based on the state of the exhaust gas purification device and the required driving force for the internal combustion engine Air-fuel ratio control means;
An exhaust gas purification control device for an internal combustion engine comprising:   The exhaust purification device request detection means includes a catalyst activity improvement request that needs to increase the exhaust gas temperature to improve the catalyst activity, and a NOx regeneration request that needs to desorb and purify NOx adsorbed on the NOx trap catalyst. At least one of the PM regeneration request that needs to burn and remove PM collected by the PM trapping filter and the S poison regeneration request that needs to burn and remove S poisoned by the NOx trap catalyst The exhaust gas purification control apparatus for an internal combustion engine according to claim 1, wherein   The cylinder control means determines the output of each working cylinder so that a sum of outputs of each working cylinder during cylinder stop operation is equal to a sum of outputs of each cylinder during all cylinder operation. Item 3. An exhaust gas purification control apparatus for an internal combustion engine according to Item 2.   The exhaust gas purification of an internal combustion engine according to claim 3, wherein the cylinder control means determines the number of stopped cylinders so that the output of each working cylinder at the time of cylinder stop operation does not exceed a predetermined value. Control device.   The predetermined value is changed depending on whether it is a catalyst activity improvement request, a NOx regeneration request, a PM regeneration request, or an S poison regeneration request, and is set to a low load side when a catalyst activity improvement request or a NOx regeneration request is made. On the other hand, the exhaust gas purification control device for an internal combustion engine according to claim 4, wherein the exhaust gas purification control device is set to a high load side at the time of PM regeneration request or S poisoning regeneration request.   The exhaust gas purification control apparatus for an internal combustion engine according to any one of claims 2 to 5, wherein the cylinder control means decreases the number of stopped cylinders as the required driving force increases.   The cylinder control means increases the number of stopped cylinders at the time of PM regeneration request or S poisoning regeneration request from the number of stopped cylinders at the time of catalyst activity improvement request or NOx regeneration request even if the required driving force is constant. The exhaust gas purification control apparatus for an internal combustion engine according to claim 6.   The exhaust purification of an internal combustion engine according to any one of claims 2 to 7, wherein the exhaust air / fuel ratio control means keeps the exhaust air / fuel ratio of the working cylinder lean when a catalyst activity improvement request is made. Control device.   The exhaust purification control apparatus for an internal combustion engine according to any one of claims 2 to 8, wherein the exhaust air / fuel ratio control means enriches the exhaust air / fuel ratio of the working cylinder when NOx regeneration is requested. .   The exhaust purification control of an internal combustion engine according to any one of claims 2 to 9, wherein the exhaust air / fuel ratio control means keeps the exhaust air / fuel ratio of the working cylinder lean when PM regeneration is requested. apparatus.   11. The internal combustion engine according to claim 10, wherein the exhaust air / fuel ratio control means controls the exhaust air / fuel ratio of the working cylinder to stoichiometric when the required driving force falls below a predetermined value when PM regeneration is requested. Exhaust purification control device.   The internal combustion engine according to any one of claims 2 to 11, wherein the exhaust air / fuel ratio control means controls the exhaust air / fuel ratio of the working cylinder to be stoichiometric or rich when an S poisoning regeneration request is made. Exhaust purification control device.   The cylinder control means stops all the cylinders when it is in a decelerating state when a catalyst activity improvement request, a NOx regeneration request, a PM regeneration request, or an S poison regeneration request is made. The exhaust gas purification control apparatus for an internal combustion engine according to any one of claims 2 to 12.   The exhaust air-fuel ratio control means performs at least one of post-injection, intake throttle strengthening, and EGR strengthening performed in an expansion stroke or an exhaust stroke after the main injection of fuel for generating a drive output for the working cylinder. The air-fuel ratio of the exhaust gas discharged from the working cylinder of the internal combustion engine and flowing into the exhaust gas purification device is controlled by being selected and executed, according to any one of claims 1 to 13. An exhaust purification control device for an internal combustion engine.   When the exhaust air / fuel ratio control means controls the exhaust air / fuel ratio by post-injection, the upper limit of the required driving force for permitting post-injection is set as follows: catalyst activity improvement request, PM regeneration request, NOx regeneration request, S poison 15. The exhaust gas purification control device for an internal combustion engine according to claim 14, wherein the exhaust gas purification control device is set to the highest level when an S poisoning regeneration request is made in the order of the regeneration request.   When the exhaust air-fuel ratio control means controls the exhaust air-fuel ratio by strengthening the intake throttle, the upper limit of the required driving force that permits the intake throttle enhancement is set at the time of catalyst activity improvement request, PM regeneration request, S poisoning regeneration request 16. The exhaust gas purification control apparatus for an internal combustion engine according to claim 14 or 15, wherein the exhaust gas purification control device is set to be highest when NOx regeneration is requested in the order of when NOx regeneration is requested.   When the air-fuel ratio control means controls the exhaust air-fuel ratio by EGR enhancement, the upper limit of the required driving force that permits EGR enhancement is set to the catalyst activity improvement request, PM regeneration request, S poisoning regeneration request, NOx regeneration The exhaust gas purification control device for an internal combustion engine according to any one of claims 14 to 16, wherein the exhaust gas purification control device is set to be highest in the order of request when NOx regeneration is requested.

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