JP5212923B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  As is well known, today's internal combustion engines are often equipped with a supercharger. Various techniques for detecting a failure of a part related to supercharging have been proposed. For example, Patent Document 1 described below describes a technique for detecting a discharge pressure of a compressor using a pressure sensor as means for detecting blockage of an air cleaner provided upstream of the intake air of the air compressor.

Japanese Patent No. 2786214

  There are various types of supercharging-related problems, and the appropriate countermeasures are different for each. For example, the supercharger itself has not failed, and some clogging may occur upstream of the turbo compressor. The cause of the clogging is that the air cleaner is clogged with dust or the like, or that the intake throttle upstream of the compressor is inoperable and becomes too throttled.

  If there is clogging upstream of the compressor, when the turbocharger operates in that state, negative pressure is generated upstream of the compressor, and oil (lubricating oil) for reducing friction of the turbocharger bearings is affected by this. And blow out. As a result, the turbocharger with less oil causes a malfunction. Further, for example, in the case of a diesel engine, the oil blown from the supercharger may flow into the engine cylinder and affect the engine output. In this case, the engine output suddenly fluctuates regardless of the driver's operation.

  When such a failure occurs, a different countermeasure from the failure of the supercharger itself is required. However, in the prior art including the above-mentioned Patent Document 1, only clogging upstream of the turbo compressor is detected separately from other troubles (for example, rotation failure of the compressor itself, air leakage downstream of the compressor, etc.). I can't do it.

  Therefore, in view of the above problems, the problem to be solved by the present invention is to provide a control device for an internal combustion engine that detects clogging upstream of a turbo compressor, distinguishing it from other problems, and appropriately copes with the clogging. There is to do.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a control device for an internal combustion engine according to the present invention includes a turbocharger including a turbine disposed in an exhaust passage of the internal combustion engine and a compressor disposed in an intake passage, and a downstream of the turbine. An exhaust gas recirculation passage for recirculating exhaust gas upstream of the compressor; a control valve provided in the exhaust gas recirculation passage for controlling the flow rate of the exhaust gas recirculated; and pressures upstream and downstream of the control valve A detection unit that detects a difference; and a determination unit that determines whether or not the intake passage upstream of the compressor is in a closed state from information on a pressure difference in the detection unit when the control valve is in a closed state. It is characterized by having.

  Thus, in the control apparatus for an internal combustion engine according to the present invention, when the control valve of the exhaust gas recirculation passage is closed, the pressure difference between the upstream and downstream of the control valve is detected, and whether or not the upstream of the compressor is blocked is determined. Therefore, the pressure difference detection means provided in the exhaust gas recirculation passage is used effectively, and the pressure value is not affected by the exhaust gas recirculated, and only the blockage upstream of the compressor is applied. It can be detected with high accuracy in distinction from defects. Therefore, it is possible to take measures to avoid the problems such as the oil blow-out from the supercharger and the fluctuation of the engine output as described above.

  Moreover, when it determines with the said obstruction | occlusion state by the said determination means, you may provide the 1st control means to reduce the supercharging pressure by the said supercharger.

  As a result, when a closed state upstream of the compressor is detected, the supercharging pressure by the supercharger is reduced. At this time, by reducing the target supercharging pressure, the flap opening degree and the rotational speed of the turbine are reduced. The actual supercharging pressure is also adjusted to decrease. As a result, the operation of the supercharger is limited, so that the oil blowout from the supercharger is suppressed even when the upstream side of the compressor is closed. Therefore, the possibility of failure of the supercharger and fluctuations in engine output due to oil are suppressed.

  In addition, a setting unit that sets a threshold value as to whether or not the pressure upstream of the compressor is normal according to an operating condition of the internal combustion engine, the determination unit adds the numerical value of the pressure difference acquired by the detection unit to the numerical value of the pressure difference. The inlet pressure of the exhaust gas recirculation passage may be added to calculate the pressure value upstream of the compressor, and the blockage state may be determined when the pressure value is smaller than the threshold set by the setting means.

  Thus, when the control valve of the exhaust gas recirculation passage is in a closed state, the upstream and downstream differential pressures and the inlet pressure are added to obtain the pressure upstream of the compressor, and if it is smaller than the threshold value, the compressor upstream is blocked. Therefore, it is possible to accurately determine the pressure upstream of the compressor by effectively using the case where the control valve of the exhaust gas recirculation passage is in the closed state, and thereby determine whether there is a blockage upstream of the compressor.

  Further, when the control valve is in an open state, the exhaust gas recirculation is calculated using the relationship between the detected value of the pressure difference by the detector and the opening of the control valve and the exhaust gas flow rate in the exhaust gas recirculation passage. Second control means for controlling the exhaust flow rate in the passage may be provided.

  Thereby, when the control valve of the exhaust recirculation passage is in the open state, the exhaust flow rate control in the exhaust gas recirculation passage is performed by adjusting the opening of the control valve, and when the control valve of the exhaust recirculation passage is in the closed state, The pressure upstream of the compressor is obtained with high accuracy, whereby the presence or absence of blockage upstream of the compressor is determined with high accuracy. Therefore, both the problem of adjusting the exhaust gas recirculation amount and determining whether there is a blockage upstream of the compressor can be solved by effectively using the case where the control valve of the exhaust gas recirculation passage is in the open state and the case where it is in the closed state.

  Moreover, when it determines with the said obstruction | occlusion state by the said determination means, a said 1st control means is good also as reducing a supercharging pressure by reducing the target supercharging pressure in supercharging pressure control.

  Thereby, by reducing the target supercharging pressure, the flap opening degree and the rotational speed of the turbine are reduced, and the actual supercharging pressure is also adjusted to decrease. Therefore, since the operation of the supercharger is restricted, the oil blowout from the supercharger is suppressed even when the upstream side of the compressor is in the closed state. Therefore, the possibility of failure of the supercharger and fluctuations in engine output due to oil are suppressed.

  In addition, an exhaust throttle for adjusting the exhaust speed flowing into the turbine is provided, and when the determination means determines that the closed state, the first control means stops supercharging pressure control and stops the exhaust pressure control. The supercharging pressure may be reduced by opening the throttle portion.

  As a result, when the upstream side of the compressor is in the closed state, the operation of the supercharger is limited to the minimum, so that the oil blowout from the supercharger is suppressed even if the upstream side of the compressor is in the closed state. Therefore, the possibility of failure of the supercharger and fluctuations in engine output due to oil are suppressed.

  Moreover, when the said determination means determines with the said obstruction | occlusion state, the said 1st control means is good also as reducing a supercharging pressure by reducing the fuel injection quantity in the said internal combustion engine.

  Thereby, when the compressor upstream is in a closed state, the in-cylinder injection amount is reduced. Accordingly, the exhaust flow rate is reduced and the rotational speed of the turbine is also reduced, so that the operation of the supercharger is limited. Therefore, even when the upstream side of the compressor is in the closed state, the oil blowout from the supercharger is suppressed. Therefore, the possibility of failure of the supercharger and fluctuations in engine output due to oil are suppressed.

The block diagram of the Example of the control apparatus of the internal combustion engine in this invention. The flowchart of a supercharger failure suppression control. The flowchart of an EGR inlet pressure detection. The figure which shows the example of the map for a low voltage | pressure EGR operating range and threshold value acquisition.

  Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a schematic diagram of a device configuration in an embodiment of a control device 1 for an internal combustion engine according to the present invention.

  FIG. 1 shows an example of an exhaust purification device 1 configured for a four-cylinder diesel engine 2 (hereinafter simply referred to as an engine). The engine 2 and the exhaust purification device 1 include an intake pipe 3, an exhaust pipe 4, a supercharger 5, a low pressure EGR pipe 6, and a high pressure EGR pipe 7. In addition, an electronic control unit 9 (ECU: Electronic Control Unit) for controlling them is provided. The engine 2 and the exhaust emission control device 1 may be mounted on an automobile. In this embodiment, a diesel engine is used as the internal combustion engine. However, the present invention is not limited to this. For example, the same effect can be obtained even when the engine is changed to a gasoline engine.

  Air is supplied to the engine 2 through the intake pipe 3. An air cleaner 30, an air flow meter 31, a first intake throttle 32, and a second intake throttle 33 are disposed in the intake pipe 3. The air cleaner 30 filters out dust and dirt in the air. The air flow meter 31 measures the intake air amount. The intake air amount here may be a mass flow rate per unit time, for example.

  The first intake throttle 32 is installed upstream of the outlet of the low pressure EGR pipe 6, and the second intake throttle 33 is installed near the inlet of the intake manifold. By adjusting the opening degree of the first intake throttle 32 and the second intake throttle 33, the amount of intake air supplied to the engine 2 increases or decreases. Of these, the first intake throttle 32 also has a function of reducing the opening of the first intake throttle 32 when, for example, it is desired to increase the exhaust gas recirculation amount by the low pressure EGR pipe 6.

  The engine 2 is equipped with an injector 21 and an engine speed sensor 22. Fuel is supplied into the cylinder by injection from the injector 21. The engine speed sensor 22 measures the speed of the engine 2 (per unit time). The engine speed sensor 22 may be, for example, a crank angle sensor that measures the rotation angle of a crank connected from the engine 2, and the detected value is sent to the ECU 9 to calculate the engine speed.

  Exhaust gas is discharged to an exhaust pipe 4 connected to the engine 2. The exhaust pipe 4 is equipped with a DPF 40 (Diesel Particulate Filter) for the purpose of exhaust purification.

  For example, the DPF 40 may have a structure in which the inlet side and the outlet side are alternately packed in a so-called honeycomb structure. The exhaust discharged during operation of the engine 2 contains PM (particulate matter), and this PM is collected inside or on the surface of the DPF 40 when the exhaust passes through the DPF wall having the above structure of the DPF 40. Is done. The DPF 40 may be a DPF with an oxidation catalyst on which an oxidation catalyst is supported.

  Whenever the estimated value of the PM amount accumulated in the DPF 40 is considered to exceed a predetermined value, the DPF 40 is burned by raising the temperature of the DPF 40 by, for example, post-injection after main injection in the engine cylinder. Just replay it. At that time, for example, a differential pressure sensor for measuring the pressure difference (front-rear differential pressure) on the inlet side and the outlet side of the DPF 40 is equipped, and the PM is calculated from the measured value and a map showing the relationship between the differential pressure and the PM deposition amount. What is necessary is just to estimate the amount of accumulation.

  In addition, this invention is not limited to the equipment of DPF40. For example, LNT (Lean NOx Trap) may be equipped without the DPF 40, or the equipment may be changed as appropriate, for example, both the DPF 40 and the LNT, and further an oxidation catalyst. When the LNT is equipped, the engine 2 stores NOx (nitrogen oxides) in the exhaust during the lean combustion period higher than the stoichiometric air-fuel ratio, and reduces the NOx stored during the rich period lower than the stoichiometric air-fuel ratio. Convert to nitrogen and discharge.

  In the exhaust pipe 4, an exhaust temperature sensor 41 that measures the exhaust temperature upstream of the DPF 40 and a muffler 42 are arranged downstream of the DPF 40 (exit of the exhaust pipe 4). The exhaust temperature is measured by the exhaust temperature sensor 41, and the exhaust noise is reduced by the muffler.

  The supercharger 5 (turbocharger) includes a compressor 50 (compressor) disposed in the intake pipe 3 and a turbine 51 disposed in the exhaust pipe 4. The turbine 51 is rotated by the exhaust gas, and the compressor 50 is operated by the rotational force to supply the compressed air to the engine 2 so that a larger power is output from the engine 2.

  The supercharger 5 may be a so-called variable nozzle turbocharger (VNT). A plurality of flaps 52 are provided in the middle of the exhaust flow path to the turbine 51 of the supercharger 5 so as to surround the turbine 51 in the circumferential direction, for example. The opening degree of the flap 52 is adjusted by a command from the ECU 9.

  When the opening of the flap 52 is adjusted so as to decrease, the exhaust gas flow velocity is increased by restricting the cross-sectional area of the exhaust gas flow path, whereby the turbine 51 rotates at a higher speed and the boost pressure (compressor 50). The pressure in the intake pipe 3 further downstream) increases. Conversely, when the opening degree of the flap 52 is lowered, the supercharging pressure is reduced. The supercharging pressure is controlled by the opening degree of the flap 52 using the above relationship. At that time, a target boost pressure may be set, a map indicating the flap opening degree that achieves the target boost pressure is obtained in advance, and the opening command value of the flap 52 may be determined using the map. . Alternatively, the flap opening degree may be commanded by feedback control.

  The low pressure EGR pipe 6 and the high pressure EGR pipe 7 are provided for the purpose of exhaust gas recirculation (EGR) from the exhaust pipe 4 to the intake pipe 3. The low pressure EGR pipe 6 recirculates (refluxs) exhaust from the turbine 51 downstream to the compressor 50 upstream, and the high pressure EGR pipe 7 from the turbine 51 upstream (exhaust manifold) to the compressor 50 downstream (intake manifold).

  The low-pressure EGR pipe 6 and the high-pressure EGR pipe 7 are equipped with EGR coolers 60 and 70 and EGR valves 61 and 71, respectively. The exhaust gas is cooled by the EGR coolers 60 and 70, and more exhaust gas can be recirculated. The exhaust gas recirculation amount is adjusted by opening and closing the EGR valves 61 and 71.

  One reason that two EGR pipes are provided in this way is that the high-pressure EGR pipe 7 alone may not ensure a sufficient EGR amount due to an increase in intake pressure due to supercharging of the turbocharger 5 at high loads. .

  In the low and medium load range, the pressure in the intake manifold (supercharging pressure) is low compared to the pressure in the exhaust manifold, and the differential pressure between the two manifolds is large. it can. However, in a high load region, the pressure of the intake manifold rises due to turbocharging, and the differential pressure between the exhaust and intake manifolds becomes small. Therefore, it is difficult for the high pressure EGR to recirculate the exhaust.

  However, if two systems of EGR are installed, in the high load region, the compressor upstream is sucked by the compressor, the negative pressure increases, and the differential pressure from the turbine downstream increases, so that the exhaust gas is easily recirculated by the low pressure EGR. Therefore, it is possible to secure the EGR amount at the time of high load by the low pressure EGR which is not affected by the increase of the intake pressure due to the turbocharger supercharging.

  The low pressure EGR pipe 6 is equipped with a differential pressure sensor 62 that measures a pressure difference between the upstream side and the downstream side of the EGR valve 61. The differential pressure sensor 62 is used to adjust the exhaust gas recirculation amount in the low pressure EGR pipe 6.

  A specific method for adjusting the exhaust gas recirculation amount is, for example, as follows. The cross-sectional area of the exhaust flow passing through the EGR valve 61 is determined by the opening degree of the EGR valve 61. If the cross-sectional area of the exhaust flow passing through the EGR valve 61 and the differential pressure across the EGR valve 61 are known, the exhaust flow rate at the EGR valve 61 can be calculated by the well-known Bernoulli theorem. When the above relationship is used, the relationship from the opening degree of the EGR valve 61 to the exhaust gas recirculation amount in the low pressure EGR pipe 6 is obtained.

  For example, an appropriate exhaust gas recirculation amount value (target value) in the low-pressure EGR pipe 6 is set in advance for each operating condition of the engine 2 and stored in the memory 90 in the form of a map. Then, the target exhaust gas recirculation amount is obtained from the map according to the operating conditions of the engine 2 every moment, and the opening degree of the EGR valve 61 is commanded so as to achieve the exhaust gas recirculation amount.

  The dotted lines shown in FIG. 1 indicate the flow of information, and the measured values of the air flow meter 31, the engine speed sensor 22, the exhaust temperature sensor 41, and the differential pressure sensor 62 are sent to the ECU 9. Further, the ECU 9 adjusts and controls the timing and amount of fuel injection to the engine 2 by the injector 21 and the opening degrees of the first intake throttle 32, the second intake throttle 33, the flap 52, and the EGR valves 61 and 71. The ECU 9 may have a structure similar to that of an ordinary computer, and may include a CPU that performs various calculations and a memory 90 that stores various types of information.

  In this embodiment, when the low pressure EGR valve 61 is in the closed state, it is detected whether or not the upstream of the compressor 50 is blocked (clogged, abnormal flow rate drop), and the blockage is detected. Performs control to limit the operation of the supercharger.

  The cause of the clogging upstream of the compressor 50 is, for example, that the air cleaner 30 is clogged with dust or dust, or that the first intake throttle 32 is malfunctioning (mechanical failure or control system failure), resulting in an over-throttle state. Can be given. If the turbocharger 5 is operated as usual with clogging upstream of the compressor 50 due to such a reason, as described above, negative pressure is generated and oil is blown out from the supercharger 5. Problems such as failure and reduced engine output may occur.

  The processing procedure of this embodiment is shown in FIG. The processing procedure of FIG. 2 (and FIG. 3 described later) may be programmed and stored in the memory 90, and the ECU 9 may automatically execute them. The flowcharts of FIGS. 2 and 3 may be continuously processed, for example, during driving of the vehicle.

  In the process of FIG. 2, first, in step S10, the ECU 9 acquires the engine speed and the in-cylinder injection amount. The engine speed may be detected by the engine speed sensor 22, and the in-cylinder injection amount may be a command value to the injector 21 by the ECU 9. Next, in S <b> 20, the ECU 9 calculates a region (operating region) for controlling the low pressure EGR valve 61. An example of this operating range is shown in FIG.

  As shown in FIG. 4, a region where the engine speed and the engine load (in-cylinder injection amount) are medium is a region where the low pressure EGR valve 61 is controlled. If the operating condition is in this region, the opening degree of the low pressure EGR valve 61 is adjusted and EGR by the low pressure EGR pipe 6 is executed (S110 to S130 described later). When the operating condition is outside this range, the low pressure EGR valve is closed (the opening degree is set to zero) and EGR through the low pressure EGR pipe 6 is not used (after S40 described later). In the present invention, in the latter case, the presence / absence of a blocked state upstream of the compressor 50 is detected, and when there is a blocked state, the operation of the supercharger 5 is limited.

  Next, in S30, the ECU 9 determines whether or not the current operating condition is located in the low pressure EGR valve control region. If the ECU 9 is located within the low pressure EGR valve control region (S30: YES), the ECU 9 proceeds to S40, and if not (S30: NO), the process proceeds to S110. When the routine proceeds to S110, the ECU 9 executes normal low pressure EGR valve control from S110 to S130.

  Specifically, first, an EGR differential pressure is acquired in S110. This may be measured by the differential pressure sensor 62. Next, an EGR flow rate is calculated in S120. The calculation of the EGR flow rate may be performed using the relationship to the EGR flow rate from the differential pressure across the EGR valve and the opening degree of the EGR valve as described above. In step S130, the low pressure EGR valve is controlled.

  Specifically, the current value of the deviation between the EGR flow rate obtained in S120 and the target EGR flow rate may be obtained, and the opening degree of the low pressure EGR valve 61 may be adjusted based on that value. The target EGR flow rate may be obtained from a map showing the relationship between the operating condition of the engine 2 and the target EGR flow rate as described above. Further, when adjusting the opening degree of the low pressure EGR valve 61, feedback control of deviation of the EGR flow rate may be performed by a controller having dynamic characteristics.

  If the process proceeds to S40, the ECU 9 proceeds to a clogging detection procedure upstream of the compressor 50. First, in S40, the ECU 9 acquires the EGR inlet pressure and the EGR pressure loss (differential pressure). The EGR differential pressure may be measured by the differential pressure sensor 62. The procedure for calculating the EGR inlet pressure is shown in FIG.

  In the process of FIG. 3, first, the intake air flow rate and the exhaust gas temperature are acquired in S200. The intake flow rate may be measured by the air flow meter 31 and the exhaust temperature may be measured by the exhaust temperature sensor 41. Next, the muffler pressure loss is calculated in S210. It has been found that the muffler pressure loss can be estimated if the intake flow rate and the exhaust temperature are known. Therefore, for example, a map indicating the relationship between the intake air flow rate, the exhaust temperature, and the muffler pressure loss is obtained in advance, and the muffler pressure loss value may be obtained from this map and the measured value obtained in S40.

  In S220, the EGR inlet pressure is calculated. This can be done by adding the muffler pressure loss and the atmospheric pressure obtained in S210. Thus, the EGR inlet pressure is obtained.

  Returning to FIG. 2, next, in S50, the ECU 9 calculates the EGR outlet pressure. This can be done by adding the EGR inlet pressure and the EGR pressure loss obtained in S40. Next, in S60, the ECU 9 calculates outlet pressure threshold values 1 and 2 (threshold values 1 and 2) used for determining whether or not the blockage is described below. Examples of threshold values 1 and 2 are shown in FIG.

  As shown in FIG. 4, the threshold value 1 is always set to be larger than the threshold value 2 for an arbitrary operation condition. In addition, both the threshold value 1 and the threshold value 2 are set so that the value becomes smaller as the rotation speed is higher and the load is higher. The setting of FIG. 4 appropriately reflects that the pressure upstream of the compressor 50 tends to decrease as the load increases and the rotation speed increases.

  In S <b> 70, the ECU 9 determines whether or not the actual outlet pressure is smaller than the threshold value 1. When it is smaller than the threshold 1 (S70: YES), the process proceeds to S80, and when it is equal to or greater than the threshold 1 (S70: NO), the process proceeds to S140. In S140, the ECU 9 performs (continues) normal supercharging control.

  Next, in S80, the ECU 9 determines whether or not the actual outlet pressure is smaller than the threshold value 2. If it is smaller than the threshold 2 (S80: YES), the process proceeds to S150, and if it is greater than or equal to the threshold 2 (S80: NO), the process proceeds to S90.

  Next, in S90, the ECU 9 determines whether or not the period during which the actual outlet pressure is smaller than the threshold value 1 continues for a predetermined period. When it continues for a predetermined period (S90: YES), the process proceeds to S150, and when it does not continue (S90: NO), the process proceeds to S100. After proceeding to S100, the ECU 9 continues the normal supercharging control. After proceeding to S150, the ECU 9 determines that clogging (intake system abnormality) upstream of the compressor 50 has occurred, and copes with it in subsequent S160.

  As described above, in the process of FIG. 2, the pressure upstream of the compressor 50 uses the period during which the low-pressure EGR valve 61 is closed. When the EGR valve 61 is open, the pressure value upstream of the compressor is affected by the recirculated exhaust gas. However, since the EGR valve 61 is closed in the above procedure, the pressure value upstream of the compressor accurately reflects clogging upstream of the compressor. doing. Therefore, clogging upstream of the compressor can be detected with high accuracy.

  In the process of FIG. 2, when the pressure upstream of the compressor 50 is very small (smaller than the threshold value 2), and when the pressure upstream of the compressor 50 is low for a certain period or longer (the state where the pressure is smaller than the threshold value 1 is constant). It is determined that clogging has occurred if it has continued for a period of time. Therefore, it is possible to make an appropriate determination by combining the small numerical value and the length of the period.

  In S160, any one of the following three processes may be executed. First, as a first process, the target supercharging pressure is reduced. As described above, in the system of FIG. 1, the boost pressure is controlled by adjusting the opening degree of the flap 52 while referring to the target boost pressure according to a command from the ECU 9. Accordingly, by reducing the target supercharging pressure, the flap opening degree and the turbine rotational speed are consequently reduced, and the actual supercharging pressure is also adjusted to decrease. As a result, the operation of the supercharger 5 (the number of rotations of the turbine 51) is limited, so that the oil blow-out from the supercharger 5 is suppressed even when the upstream side of the compressor is closed. Therefore, the possibility of failure of the supercharger 5, fluctuations in engine output due to oil, and the like are suppressed.

  As the second process, the supercharging control is stopped. That is, the adjustment of the opening degree of the flap 52 is stopped while the opening degree of the flap 52 is kept at the maximum (fully opened state). As a result, the operation of the supercharger 5 (the rotational speed of the turbine 51) is suppressed to the minimum value, so that the oil blow-off from the supercharger 5 is suppressed even when the upstream side of the compressor is closed. Therefore, the possibility of failure of the supercharger 5, fluctuations in engine output due to oil, and the like are suppressed.

  As a third process, the in-cylinder injection amount in the engine 2 is reduced. As a result, the exhaust gas flow rate is reduced, and the rotational speed of the turbine is also reduced, so that the operation of the supercharger 5 is limited. Therefore, even if the upstream side of the compressor is closed, the oil blow-out from the supercharger 5 is suppressed. Accordingly, the possibility of failure of the supercharger 5 and fluctuations in engine output due to oil are suppressed. The above is the processing of FIG.

  In the above embodiment, the low pressure EGR pipe 6 constitutes an exhaust gas recirculation passage. The low pressure EGR valve 61 constitutes a control valve. The differential pressure sensor 62 constitutes a detection unit. The processing procedure from S70 to S90 and the ECU 9 constitute a determination means. The procedure of S160 and the ECU 9 constitute the first control means. The procedure of S130 and the ECU 9 constitute the second control means. The procedure of S60 and the ECU 9 constitute setting means. The flap 52 constitutes an exhaust throttle part.

1 Exhaust purification device 2 Engine (internal combustion engine)
3 Intake pipe (intake passage)
4 Exhaust pipe (exhaust passage)
5 Supercharger 6 Low pressure EGR pipe (exhaust gas recirculation passage)
7 High pressure EGR pipe 9 Electronic control unit (ECU)
30 Air cleaner 32 First intake throttle 52 Flap (exhaust throttle)
61 Low pressure EGR valve (control valve)
62 Differential pressure sensor (detector)

Claims (7)

A supercharger comprising a turbine disposed in an exhaust passage of an internal combustion engine and a compressor disposed in an intake passage;
An exhaust gas recirculation passage for recirculating exhaust gas from downstream of the turbine to upstream of the compressor;
A control valve provided in the exhaust gas recirculation passage for controlling the flow rate of the exhaust gas flow to be recirculated;
A detection unit for detecting a pressure difference between upstream and downstream of the control valve;
When the control valve is in a closed state, determination means for determining whether or not the intake passage upstream of the compressor is in a closed state from information on a pressure difference in the detection unit;
A control apparatus for an internal combustion engine, comprising:   2. The control device for an internal combustion engine according to claim 1, further comprising first control means for reducing a supercharging pressure by the supercharger when the determination means determines that the closed state. A setting means for setting a threshold value as to whether the pressure upstream of the compressor is normal or not according to operating conditions of the internal combustion engine;
The determination unit calculates the pressure value upstream of the compressor by adding the inlet pressure of the exhaust gas recirculation passage to the numerical value of the pressure difference acquired by the detection unit, and is smaller than the threshold value set by the setting unit. The control device for an internal combustion engine according to claim 1 or 2, wherein the control unit determines that the closed state.   When the control valve is in an open state, the exhaust gas recirculation passage is obtained by using the relationship between the detected value of the pressure difference by the detection unit and the opening of the control valve to the exhaust gas flow rate in the exhaust gas recirculation passage. The control device for an internal combustion engine according to any one of claims 1 to 3, further comprising second control means for performing exhaust gas flow rate control.   3. The internal combustion engine according to claim 2, wherein the first control unit reduces the boost pressure by reducing a target boost pressure in the boost pressure control when the determination unit determines that the closed state. Control device. An exhaust throttle for adjusting the exhaust speed flowing into the turbine,
The said 1st control means stops supercharging pressure control, and reduces the supercharging pressure by making the said exhaust throttle part an open state when it determines with the said obstruction | occlusion state by the said determination means. The internal combustion engine control device described.   3. The control device for an internal combustion engine according to claim 2, wherein the first control unit reduces the supercharging pressure by reducing the fuel injection amount in the internal combustion engine when the determination unit determines that the closed state. .

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