JP5365264B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine including a variable capacity turbocharger.

  Patent Document 1 discloses a technique for controlling the nozzle opening degree of an exhaust turbine in a variable capacity turbocharger according to the degree of clogging of the DPF.

  Patent Document 2 discloses a technique for feedback control of the actual boost pressure with respect to the target boost pressure of the diesel engine.

JP-A-2005-48743 JP 2005-264930 A

However, in Patent Document 1, since the nozzle opening of the variable capacity turbocharger is corrected according to the clogging of the DPF, the capacity can be changed if the DPF is clogged under any operating condition. type nozzle opening degree of the turbocharger will be corrected in the open can end, there is a possibility that acceleration becomes dull.

  Further, as in Patent Document 2, when the actual supercharging pressure is feedback-controlled with respect to the target supercharging pressure, if the PM accumulation amount of the DPF is large, the deviation of the supercharging pressure becomes large and the feedback amount increases. Therefore, in some cases, the exhaust pressure may exceed the allowable value of the exhaust system parts.

  Therefore, the control apparatus for an internal combustion engine of the present invention feedback-controls the nozzle opening of the exhaust turbine of the variable capacity turbocharger based on the target exhaust pressure and the actual exhaust pressure. Depending on the state of the exhaust system, the ratio of the value based on the target boost pressure and the actual boost pressure used when determining the nozzle opening of the exhaust turbine and the value based on the target exhaust pressure and the actual exhaust pressure It is characterized by changing.

  According to the present invention, since it is possible to feedback control the opening degree of the exhaust turbine so that the exhaust pressure does not become excessively high, it is possible to achieve both protection of exhaust system parts and acceleration demand.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the whole structure of the diesel engine to which the control apparatus of the internal combustion engine which concerns on this invention is applied. The flowchart which shows the flow of control at the time of calculating supercharging pressure deviation (DELTA) Pbst. The flowchart which shows the flow of control at the time of calculating exhaust pressure deviation (DELTA) Pexh. Calculation map of target exhaust pressure tPexh. The flowchart which shows the flow of control of the nozzle opening degree of the exhaust turbine of a turbocharger. Calculation map of contribution rate Kp. The timing chart which showed the mode of the change of various parameters at the time of transition. The flowchart which shows the flow of control of the nozzle opening degree of the exhaust turbine of the turbocharger in 2nd Embodiment. The flowchart which shows the flow of control of the nozzle opening degree of the exhaust turbine of the turbocharger in 3rd Embodiment.

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

  FIG. 1 shows an overall configuration of a diesel engine 1 to which the present invention is applied. The diesel engine 1 performs a relatively large amount of exhaust gas recirculation (EGR), and an EGR passage 4 is provided between the exhaust passage 2 and the collector portion 3 a of the intake passage 3. An EGR control valve 6 and an EGR cooler 7 are interposed in the EGR passage 4. The opening degree of the EGR control valve 6 is controlled by the control unit 5 so as to obtain a predetermined EGR rate corresponding to the operating conditions. For example, the EGR rate becomes maximum in the low speed and low load region, and the EGR rate decreases as the rotational speed and load increase.

  The diesel engine 1 includes a common rail fuel injection device 10. In the common rail type fuel injection device 10, the fuel pressurized by the supply pump 11 is temporarily stored in the pressure accumulating chamber (common rail) 13 through the high pressure fuel supply passage 12, and then, from the pressure accumulating chamber 13 to each cylinder. The fuel is distributed to the fuel injection nozzles 14 and injected according to the opening and closing of the fuel injection nozzles 14. The fuel pressure in the pressure accumulating chamber 13 is variably adjusted by a pressure regulator (not shown), and the pressure accumulating chamber 13 is provided with a fuel pressure sensor 15 for detecting the fuel pressure. A known glow plug 18 is disposed in the combustion chamber.

  The diesel engine 1 also includes a turbocharger 21 that is provided with an exhaust turbine 22 and a compressor 23 on the same axis. The exhaust turbine 22 is located downstream of the EGR passage 4 branching point of the exhaust passage 2 and has a variable displacement configuration in which a variable nozzle 24 as a capacity adjusting means is provided at the scroll inlet of the exhaust turbine 22. Yes. That is, when the opening of the variable nozzle 24 is small, the characteristics of the small capacity are suitable for conditions with a small exhaust flow rate such as a low speed region, and when the opening of the variable nozzle 24 is large, the characteristic is as in the high speed region. Large capacity characteristics suitable for conditions with a large exhaust flow rate. The variable nozzle 24 is driven by a diaphragm actuator 25 that responds to a control pressure (control negative pressure). An exhaust pressure sensor 17 that detects an actual exhaust pressure rPexh that is the pressure in the exhaust passage 2 is disposed upstream of the exhaust turbine 22.

  In addition, in the exhaust passage 2 downstream of the exhaust turbine 22, an oxidation catalyst 27 that oxidizes CO, HC, and the like in the exhaust, and a NOx trap catalyst 28 that performs NOx treatment are sequentially arranged. The NOx trap catalyst 28 adsorbs NOx when the exhaust air-fuel ratio of the inflowing exhaust gas is lean, and when the oxygen concentration of the inflowing exhaust gas is reduced, releases the adsorbed NOx and purifies it by catalytic action. Is. On the downstream side of the NOx trap catalyst 28, a particulate collection filter (Diesel particulate filter: DPF) 29 with a catalyst for collecting and removing exhaust particulates (PM) is further provided. As this DPF 29, for example, a wall flow honeycomb structure (so-called plugging type) in which a large number of honeycomb-shaped fine passages are formed in a columnar filter material such as cordierite and the ends thereof are alternately closed. These filters are used.

  In the DPF 29, the pressure loss of the DPF 29 changes with the accumulation of exhaust particulates. Therefore, a differential pressure sensor 32 that detects a pressure difference between the inlet side and the outlet side of the DPF 29 is provided. Of course, instead of the differential pressure sensor 32 that directly detects the pressure difference, a pressure sensor may be provided on each of the inlet side and the outlet side to obtain the pressure difference.

  An air flow meter 35 for detecting the amount of intake air, that is, the amount of fresh air is disposed upstream of the compressor 23 interposed in the intake passage 3, and an air cleaner 36 is positioned further upstream. On the inlet side of the air cleaner 36, an atmospheric pressure sensor 37 for detecting an outside air pressure, that is, an atmospheric pressure, and an outside air temperature sensor 38 for detecting an outside air temperature are arranged. An intercooler 39 for cooling the supercharged high-temperature air is provided between the compressor 23 and the collector unit 3a.

  Further, an intake throttle valve 41 that restricts the amount of fresh air is interposed on the inlet side of the collector portion 3a of the intake passage 3. The intake throttle valve 41 is driven to open and close by a control signal from the control unit 5. Further, a supercharging pressure sensor 44 that detects an actual supercharging pressure rPbst that is a pressure in the intake passage 3 is provided between the intake throttle valve 41 and the intercooler 39.

  The control unit 5 that controls the injection amount and injection timing of the fuel injection device 10, the opening degree of the EGR control valve 6, the opening degree of the variable nozzle 24, etc. includes the depression amount of the accelerator pedal in addition to the sensors described above. Detection signals of sensors such as an accelerator opening sensor 46 to detect, a rotation speed sensor 47 to detect engine rotation speed, and a water temperature sensor 48 to detect cooling water temperature are input.

  The control unit 5 calculates the supercharging pressure deviation ΔPbst between the target supercharging pressure tPbst and the actual supercharging pressure rPbst and the exhaust pressure deviation ΔPexh between the target exhaust pressure tPexh and the actual exhaust pressure rPexh. Based on the pressure deviation ΔPbst and the exhaust pressure deviation ΔPexh, the nozzle opening degree of the exhaust turbine 22 of the turbocharger 21 is feedback-controlled.

  FIG. 2 is a flowchart showing the flow of control when calculating the supercharging pressure deviation ΔPbst.

  In step (hereinafter simply referred to as S) 11, the engine speed Ne and the fuel injection amount Qf are read.

  In S12, the target boost pressure tPbst is calculated using the engine speed Ne and the fuel injection amount Qf. In S13, the actual boost pressure rPbst is read.

  In S14, a supercharging pressure deviation ΔPbst that is a difference between the target supercharging pressure tPbst and the actual supercharging pressure rPbst is calculated.

  FIG. 3 is a flowchart showing the flow of control when calculating the exhaust pressure deviation ΔPexh.

  In S21, the actual exhaust pressure rPexh is read.

  In S22, the actual exhaust pressure rPexh is compared with the upper exhaust pressure UpPexh of the exhaust system. If so, the process proceeds to S24. The upper limit exhaust pressure UpPexh is a fixed value set in advance from the viewpoint of protecting the exhaust system components.

  In S23, the target exhaust pressure tPexh is set to the upper limit exhaust pressure UpPexh, and the process proceeds to S25.

  In S24, the target exhaust pressure tPexh is calculated using the supercharging pressure deviation ΔPbst. In the present embodiment, the target exhaust pressure tPexh is calculated using a map as shown in FIG. Since it is considered that the driver's acceleration request is higher as the supercharging pressure deviation ΔPbst becomes larger, the target exhaust pressure tPexh is set to become larger as the supercharging pressure deviation ΔPbst becomes larger. However, as apparent from FIG. 4, when the supercharging pressure deviation ΔPbst is “0”, the actual exhaust pressure rPexh becomes the target exhaust pressure tPexh, and when the supercharging pressure deviation ΔPbst increases to some extent, the target exhaust pressure tPexh becomes the upper limit exhaust pressure. It sticks to the pressure UpPexh.

  In S25, the exhaust pressure deviation ΔPexh, which is the difference between the target exhaust pressure tPexh and the actual exhaust pressure rPexh, is calculated.

  FIG. 5 is a flowchart showing a flow of control of the nozzle opening degree of the exhaust turbine 22 of the turbocharger 21.

  In S31, the actual exhaust pressure rPexh is read.

  In S32, ΔMaxPexh which is a difference between the upper limit exhaust pressure UpPexh and the actual exhaust pressure rPexh is calculated.

  In S33, the contribution rate Kp is calculated using ΔMaxPexh. In the present embodiment, the contribution rate Kp is calculated using a map as shown in FIG. This contribution rate Kp determines the contribution ratio of the supercharging pressure deviation ΔPbst and the exhaust pressure deviation ΔPexh in the feedback control of the nozzle opening of the exhaust turbine. The larger the ΔMaxPexh, the greater the contribution rate Kp. Is set to The contribution rate Kp is a value in the range of 0 ≦ Kp ≦ 1. In other words, the contribution rate Kp is an index of how much the actual exhaust pressure rPexh can be increased to the upper limit exhaust pressure UpPexh.

  In S35, a pressure deviation ΔP is calculated. The pressure deviation ΔP is a value obtained by weighting the supercharging pressure deviation ΔPbst and the exhaust pressure deviation ΔPexh by the contribution rate Kp, and adding them together. The value obtained by multiplying the contribution rate Kp by the supercharging pressure deviation ΔPbst, 1 is the sum of the value obtained by subtracting the contribution rate Kp from 1 and multiplying by the exhaust pressure deviation ΔPexh.

  In S36, the feedback amount in the feedback control of the nozzle opening of the exhaust turbine is calculated based on the pressure deviation ΔP. More specifically, by using the pressure deviation ΔP, the control amount for proportional control, the control amount for differential control, and the control amount for integral control in so-called PID control are calculated, and the feedback amount consisting of these three control amounts is calculated. calculate.

  In the steady state, as apparent from FIG. 6, the contribution rate Kp = 1, and the value of the term including the exhaust pressure deviation ΔPexh in the calculation formula of the pressure deviation ΔP is “0”. Based on the deviation ΔPbst, feedback control of the nozzle opening of the exhaust turbine is performed. In the normal turbine map, the optimum supercharging pressure for each operation region is obtained by adaptation and stored in the control unit 5, so that it is more effective to perform feedback control of the nozzle opening of the exhaust turbine based on the supercharging pressure deviation ΔPbst. This is more advantageous in terms of fuel consumption and exhaust performance than performing feedback control of the nozzle opening of the exhaust turbine based on the deviation ΔPexh.

  FIG. 7 is a timing chart showing how various parameters change during a transition.

  When the accelerator pedal is depressed by the driver and the accelerator opening (ACCP) increases, the boost pressure deviation ΔPbst increases.

  Here, a characteristic line A in FIG. 7 represents a change in supercharging pressure when feedback control of the nozzle opening of the exhaust turbine is performed based only on the supercharging pressure deviation ΔPbst, and a characteristic line B in FIG. Represents a change in exhaust pressure when feedback control of the nozzle opening of the exhaust turbine is performed based only on the supercharging pressure deviation ΔPbst.

  When feedback control of the nozzle opening of the exhaust turbine is performed based only on the supercharging pressure deviation ΔPbst at the time of transition, the supercharging pressure follows the target supercharging pressure tPbst as shown by the characteristic line A, but the exhaust pressure May exceed the upper limit exhaust pressure UpPexh, as indicated by the characteristic line B, due to factors such as clogging in the DPF 29 or variations in parts such as the turbocharger 21 and the environment (high altitude traveling). is there.

  In contrast, in the above-described embodiment, the nozzle opening degree of the exhaust turbine 22 is feedback-controlled based on the supercharging pressure deviation ΔPbst and the exhaust pressure deviation ΔPexh at the time of transition, and the supercharging pressure is determined according to the state of the exhaust system. Since the contribution ratio of the deviation ΔPbst and the exhaust pressure deviation ΔPexh is changed, the actual exhaust pressure rPexh is controlled so as not to exceed the upper limit exhaust pressure UpPexh. This is because the contribution rate Kp decreases as the actual exhaust pressure rPexh approaches the upper limit exhaust pressure UpPexh and ΔMaxPexh decreases, and therefore the contribution ratio of the exhaust pressure deviation ΔPexh in the feedback control of the nozzle opening increases. .

  In FIG. 7, before the actual supercharging pressure rPbst reaches the target supercharging pressure tPbst, the actual exhaust pressure rPexh reaches the upper limit exhaust pressure UpPexh. This is because the increase in the actual supercharging pressure rPbst is delayed compared to the increase in the actual exhaust pressure rPexh because the variable nozzle 24 in the turbocharger 21 is located on the exhaust side. For this reason, in the present embodiment, the actual boost pressure rPbst deviates from the target boost pressure tPbst, but this prevents an excessive increase in exhaust pressure and protects exhaust system components.

  That is, in the above-described embodiment, the nozzle opening degree of the exhaust turbine 22 is feedback-controlled so that the exhaust pressure does not become excessively high, so that the exhaust pressure can be prevented from exceeding an allowable range, and the component Both compensation and acceleration requirements can be implemented with high accuracy. That is, the maximum acceleration request can be realized within the allowable exhaust pressure range.

  Further, when calculating the contribution rate Kp using ΔMaxPexh, the blockage rate of the DPF 29 may be taken into consideration. That is, as indicated by the broken line in FIG. 6 described above, the contribution rate Kp may be set to be smaller as the blocking ratio of the DPF 29 is larger. In other words, the contribution rate Kp may be determined so that the rate of contribution of the exhaust pressure deviation ΔPexh increases as the blocking rate of the DPF 29 increases.

  Therefore, in the second embodiment of the present invention, the pressure difference between the inlet side and the outlet side of the DPF 29 is detected by the differential pressure sensor 32, and the blockage ratio of the DPF 29 is calculated according to the detected pressure difference. Yes. The blockage rate of the DPF 29 is calculated using, for example, a blockage rate calculation map that associates the blockage rate of the DPF 29 with the pressure difference between the inlet side and the outlet side of the DPF 29. The blockage ratio calculation map is set so that the blockage ratio of the DPF 29 increases as the pressure difference between the inlet side and the outlet side of the DPF 29 increases.

  FIG. 8 is a flowchart showing a flow of control of the nozzle opening degree of the exhaust turbine 22 of the turbocharger 21 according to the second embodiment of the present invention, in which the contribution rate Kp is calculated according to the blockage rate of the DPF 29. is there.

  In S41, the pressure difference between the inlet side and the outlet side of the DPF 29, which is a detected value of the differential pressure sensor 32, is read.

  In S42, the blockage ratio of the DPF 29 is calculated from the pressure difference between the inlet side and the outlet side of the DPF 29 read in S41. As the pressure difference between the inlet side and the outlet side of the DPF 29 increases, the calculated blockage ratio of the DPF 29 increases.

  In S45, the contribution rate Kp is calculated using ΔMaxPexh. In the second embodiment, there are a plurality of Kp calculation maps used when calculating the contribution rate Kp. As shown by the broken line in FIG. 6 described above, the contribution rate Kp decreases as the blockage ratio of the DPF 29 increases. The Kp calculation map set so as to be used is used. Instead of preparing a plurality of maps used when calculating the contribution rate Kp, the contribution rate Kp calculated using the reference Kp calculation map may be corrected according to the blockage rate of the DPF 29.

  S43 and S44 in FIG. 8 perform the same processing as S31 and S32 in FIG. 5 described above, and S46 to S48 in FIG. 8 perform the same processing as S34 to S36 in FIG.

  In this way, when calculating the contribution rate Kp, if the pressure loss of the DPF 29 is taken into account, both the component compensation and the acceleration request can be performed with higher accuracy.

  Further, as in the third embodiment of the present invention, the feedback gain may be calculated according to the blockage rate of the DPF 29.

  In the third embodiment, the blocking ratio of the DPF 29 is calculated by the differential pressure sensor 32 according to the pressure difference between the inlet side and the outlet side of the DPF 29. Then, the feedback gain is corrected using the feedback gain correction value calculated according to the blockage ratio of the DPF 29. That is, a feedback gain correction value is calculated for each of the above-described proportional gain, differential gain, and integral gain. In other words, the proportional gain, differential gain, and integral gain, which are feedback gains, are respectively corrected by the corresponding feedback gain correction values.

  Each feedback gain correction value is calculated using, for example, a feedback gain correction value calculation map that associates the feedback gain correction value with the blockage rate of the DPF 29. Each feedback gain correction value calculation map is set so that the feedback gain correction value decreases as the blocking ratio of the DPF 29 increases.

  FIG. 9 is a flowchart showing a flow of control of the nozzle opening degree of the exhaust turbine 22 of the turbocharger 21 in the third embodiment of the present invention, in which the feedback gain is calculated according to the blockage ratio of the DPF 29. .

  S51 to S55 in FIG. 9 perform the same processing as S31 to S35 in FIG.

  In S56, the pressure difference between the inlet side and the outlet side of the DPF 29, which is a detection value of the differential pressure sensor 32, is read.

  In S57, the blockage ratio of the DPF 29 is calculated from the pressure difference between the inlet side and the outlet side of the DPF 29 read in S41. As the pressure difference between the inlet side and the outlet side of the DPF 29 increases, the calculated blockage ratio of the DPF 29 increases.

  In S58, each feedback gain correction value is calculated from the blockage ratio of the DPF 29. As described above, each feedback gain correction value becomes smaller as the blockage ratio of the DPF 29 increases. This is to prevent the nozzle opening degree of the exhaust turbine 22 that is feedback-controlled from hunting with respect to the target value from the viewpoint of protecting the exhaust system parts when the blocking ratio of the DPF 29 is large. In order to reduce the response speed of feedback control, each feedback gain is reduced.

  In S59, the control amount for proportional control, the control amount for differential control, and the control amount for integral control are calculated using the pressure deviation ΔP, and the exhaust turbine 22 is calculated from these three control amounts. The feedback amount in the feedback control of the nozzle opening is calculated. Therefore, the feedback amount calculated in S59 is small when the blocking ratio of the DPF 29 is large.

  As described above, even when each feedback gain correction value is calculated in accordance with the blockage ratio of the DPF 29, it is possible to more accurately carry out both the component compensation and the acceleration request.

  The blockage ratio of the DPF 29 can also be calculated using the PM accumulation amount of the DPF 29, and can also be calculated using the pressure difference between the inlet side and the outlet side of the DPF 29 and the exhaust flow rate. is there.

  The amount of PM deposited on the DPF 29 can be calculated by a method that has already been known, for example, from Japanese Patent Application Laid-Open No. 2005-48743.

  Further, if the blockage rate of the DPF 29 is calculated using the pressure difference between the inlet side and the outlet side of the DPF 29 and the exhaust gas flow rate, the blockage rate of the DPF 29 is calculated only from the pressure difference between the inlet side and the outlet side of the DPF 29. Compared to the case where the blockage rate of the DPF 29 is calculated using the above, the blockage rate of the DPF 29 can be calculated with higher accuracy. The exhaust gas flow rate can be calculated from the amount of fresh air flowing into the cylinder, the engine speed Ne, and the fuel injection amount Qf.

  The technical ideas of the present invention that can be grasped from the above-described embodiments will be listed together with their effects.

(1) A variable capacity turbocharger that can variably control the nozzle opening of the exhaust turbine, and a supercharge that detects an actual supercharging pressure that is a pressure in the intake passage on the downstream side of the compressor of the turbocharger. feeding back the pressure detecting means, and a target supercharging pressure calculation means for calculating a target boost pressure in accordance with the operating conditions, the nozzle opening degree of the exhaust turbine have groups Dzu the said target supercharging pressure actual boost pressure In a control apparatus for an internal combustion engine provided with a feedback control means, target exhaust pressure calculation means for calculating a target exhaust pressure according to operating conditions, and actual exhaust pressure that is a pressure in an exhaust passage on the turbine upstream side of the turbocharger. Exhaust pressure detecting means for detecting pressure, and the feedback control means further feedback-controls the nozzle opening of the exhaust turbine based on the target exhaust pressure and the actual exhaust pressure. Contribution of a value based on the target supercharging pressure and the actual supercharging pressure, and a value based on the target exhaust pressure and the actual exhaust pressure, used when determining the nozzle opening of the exhaust turbine according to the state of the system Change the percentage to perform. This makes it possible to feedback-control the nozzle opening of the exhaust turbine so that the exhaust pressure does not become excessively high, so that both protection of the exhaust system parts and acceleration requirements can be achieved.

(2) In the control device for an internal combustion engine according to (1), the feedback control means includes a deviation between the target boost pressure and the actual boost pressure, and a deviation between the target exhaust pressure and the actual exhaust pressure. Is a means for feedback-controlling the nozzle opening of the exhaust turbine based on the above, and determining the state of the exhaust system according to a deviation of the actual exhaust pressure with respect to a preset upper exhaust pressure, the larger the deviation of the actual exhaust pressure, contributing rate of the supercharging pressure deviation against the feedback control of the nozzle opening degree of the exhaust turbine is increased. As a result, the exhaust opening nozzle opening is feedback controlled so that the exhaust pressure does not become excessively high, so that the exhaust pressure can be prevented from exceeding an allowable range, and both component compensation and acceleration requirements can be achieved. Can be carried out with high accuracy. That is, the maximum acceleration request can be realized within the allowable exhaust pressure range.

(3) In the control device for an internal combustion engine according to (2), the ratio of the boost pressure deviation and the exhaust pressure deviation contributing to the feedback control is specifically calculated according to the blockage ratio of the exhaust system. Is done.

  (4) In the control device for an internal combustion engine according to (3), specifically, the ratio of the boost pressure deviation and the exhaust pressure deviation to the feedback control is determined by the upper limit exhaust pressure and the actual exhaust pressure. Calculated according to the upper limit exhaust pressure difference that is the difference from the pressure and the blockage rate, and the smaller the upper limit exhaust pressure difference and the greater the blockage rate, the greater the rate of contribution of the exhaust pressure deviation. .

  (5) In the control device for an internal combustion engine according to any one of (1) to (4), a feedback gain in the feedback control is calculated according to a blockage ratio of an exhaust system, and the higher the blockage ratio, Reduce the feedback gain.

  (6) In the control device for an internal combustion engine according to any one of (3) to (5), specifically, the blockage rate is a blockage rate of a DPF provided in the exhaust passage.

  (7) In the control device for an internal combustion engine according to (6), the blockage ratio of the DPF is specifically calculated from a differential pressure before and after the DPF.

  (8) In the control device for an internal combustion engine according to any one of (1) to (7), specifically, the target exhaust pressure is calculated according to a difference between the target boost pressure and the actual boost pressure. To do.

  (9) In the control device for an internal combustion engine according to any one of (1) to (8), specifically, the target exhaust pressure is set between the upper limit exhaust pressure and the actual exhaust pressure. When the actual exhaust pressure exceeds the upper limit exhaust pressure, the upper limit exhaust pressure is set as the target exhaust pressure.

  (10) In the control device for an internal combustion engine according to any one of (1) to (8), specifically, the target exhaust pressure is a difference between the target boost pressure and the actual boost pressure. The smaller the value is, the closer to the actual exhaust pressure is set, and when the supercharging pressure deviation disappears, the actual exhaust pressure is set as the target exhaust pressure.

DESCRIPTION OF SYMBOLS 1 ... Diesel engine 21 ... Turbocharger 22 ... Exhaust turbine 23 ... Compressor 24 ... Variable nozzle

Claims (11)

A variable capacity turbocharger capable of variably controlling the nozzle opening of the exhaust turbine;
A supercharging pressure detecting means for detecting an actual supercharging pressure which is a pressure in the intake passage on the downstream side of the compressor of the turbocharger;
A target boost pressure calculating means for calculating a target boost pressure according to operating conditions;
An exhaust pressure detecting means for detecting an actual exhaust pressure that is a pressure in an exhaust passage on the turbine upstream side of the turbocharger;
A target exhaust pressure calculating means for calculating a target exhaust pressure according to operating conditions;
The controller of an internal combustion engine and a feedback control means for feedback control of the nozzle opening degree of the previous SL exhaust turbine,
The feedback control means is based on the supercharging pressure deviation that is a deviation between the target supercharging pressure and the actual supercharging pressure, and the exhaust pressure deviation that is a deviation between the target exhaust pressure and the actual exhaust pressure. In addition to feedback control of the nozzle opening of the exhaust turbine,
A control apparatus for an internal combustion engine, wherein a ratio of the supercharging pressure deviation and the exhaust pressure deviation that contributes to the feedback control is changed according to an exhaust system state. Depending on the deviation of the actual discharge pressure relative to pre Me set upper limit the exhaust pressure, determines the state of the exhaust system, the upper limit greater deviation of the actual discharge pressure relative to the exhaust pressure, nozzle opening degree of the exhaust turbine 2. The control device for an internal combustion engine according to claim 1, wherein a ratio of the boost pressure deviation to the feedback control increases.   3. The control device for an internal combustion engine according to claim 2, wherein a ratio of the boost pressure deviation and the exhaust pressure deviation contributing to the feedback control is calculated according to an exhaust system blockage ratio. A variable capacity turbocharger capable of variably controlling the nozzle opening of the exhaust turbine;
  A supercharging pressure detecting means for detecting an actual supercharging pressure which is a pressure in the intake passage on the downstream side of the compressor of the turbocharger;
  A target boost pressure calculating means for calculating a target boost pressure according to operating conditions;
  An exhaust pressure detecting means for detecting an actual exhaust pressure that is a pressure in an exhaust passage on the turbine upstream side of the turbocharger;
  A target exhaust pressure calculating means for calculating a target exhaust pressure according to operating conditions;
  In a control device for an internal combustion engine comprising feedback control means for feedback control of the nozzle opening of the exhaust turbine,
  The feedback control means is based on the supercharging pressure deviation that is a deviation between the target supercharging pressure and the actual supercharging pressure, and the exhaust pressure deviation that is a deviation between the target exhaust pressure and the actual exhaust pressure. In addition to feedback control of the nozzle opening of the exhaust turbine, the ratio of the supercharging pressure deviation and the exhaust pressure deviation contributing to the feedback control is changed according to the state of the exhaust system,
  The contribution ratio of the boost pressure deviation and the exhaust pressure deviation to the feedback control is calculated according to the exhaust system blockage ratio,
  A state of the exhaust system is determined according to a deviation of the actual exhaust pressure with respect to a preset upper limit exhaust pressure, and as the deviation of the actual exhaust pressure with respect to the upper limit exhaust pressure increases, the nozzle opening degree of the exhaust turbine increases. A control apparatus for an internal combustion engine, wherein a ratio of the boost pressure deviation to feedback control contributes to increase. The ratio of contribution of the supercharging pressure deviation and the exhaust pressure deviation to the feedback control is calculated according to an upper limit exhaust pressure difference that is a difference between the upper limit exhaust pressure and the actual exhaust pressure, and the blocking ratio, the upper limit as exhaust pressure difference amount is small, also increases the closing ratio control apparatus for an internal combustion engine according to claim 3 or 4, characterized in that contributes ratio of the exhaust pressure deviation is large. Wherein the feedback gain in the feedback control is calculated in accordance with the closure rate of the exhaust system, the blocking ratio increases, the internal combustion engine according to any one of claims 1 to 5, characterized in that to reduce the feedback gain Control device. The control apparatus for an internal combustion engine according to any one of claims 3 to 6 , wherein the blockage ratio is a blockage ratio of a DPF provided in the exhaust passage. The control device for an internal combustion engine according to claim 7 , wherein the blockage ratio of the DPF is calculated from a differential pressure before and after the DPF. The control device for an internal combustion engine according to any one of claims 1 to 8 , wherein the target exhaust pressure is calculated according to a difference between the target boost pressure and the actual boost pressure. The target exhaust pressure is set between the upper limit exhaust pressure and the actual exhaust pressure, and when the actual exhaust pressure exceeds the upper limit exhaust pressure, the upper limit exhaust pressure is set as the target exhaust pressure. control apparatus for an internal combustion engine according to any one of claims 1 to 9, characterized in Rukoto. The target exhaust pressure is set to be closer to the actual exhaust pressure as the difference between the target supercharging pressure and the actual supercharging pressure becomes smaller, and when the supercharging pressure deviation disappears, the target exhaust pressure is set as the target exhaust pressure. The control device for an internal combustion engine according to any one of claims 1 to 9 , wherein an actual exhaust pressure is set.

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