JP4464636B2 - Abnormality detection device for internal combustion engine - Google Patents

Description

  The present invention relates to an apparatus for detecting abnormalities in various devices such as a variable nozzle turbocharger and an EGR valve provided in each of a plurality of exhaust passages of an internal combustion engine.

As a device for detecting abnormalities of turbochargers provided in each of a plurality of exhaust passages of an internal combustion engine, a difference in supercharging pressure by each turbocharger is detected by a differential pressure switch, and a differential pressure exceeding a predetermined value is detected. In some cases, an apparatus that generates a warning by regarding that an abnormality has occurred is known (see, for example, Patent Document 1). In addition, Patent Documents 2 to 6 exist as prior art documents related to the present invention.
Japanese Utility Model Publication 2-41308 JP 2000-345850 A JP 2002-227695 A JP 2000-291494 A JP-A-9-317568 Japanese Patent Laid-Open No. 6-213044

  In the abnormality detection device described in Patent Document 1 described above, a differential pressure switch having a pair of pressure chambers is prepared with a diaphragm interposed therebetween, and the supercharging pressure of each turbocharger is introduced into each pressure chamber of the differential pressure switch. By doing so, the differential pressure is detected by replacing the difference in supercharging pressure with the amount and direction of deflection of the diaphragm. However, such a differential pressure switch is a dedicated product used only for pressure comparison, and its installation leads to a complicated configuration of the abnormality detection device and an increase in cost. Here, the abnormality detection of the turbocharger is taken as an example. However, in an internal combustion engine having a plurality of cylinder groups, swirl control valves, EGR valves, EGR are provided as accessory devices that affect the operation state of each cylinder group. Various devices such as a cooler are provided for each cylinder group, and there is a problem similar to that in the case of the turbocharger described above regarding abnormality detection of these attached devices.

  In the internal combustion engine having a plurality of cylinder groups, the present invention detects an abnormality of an accessory device that affects the intake state of each cylinder group by using a general-purpose detection means provided for controlling the intake state. An object of the present invention is to provide an anomaly detection device capable of performing the above.

  The present invention solves the above-described problems by an abnormality detection apparatus described below.

Abnormal detecting device of the present invention, the intake side is connected to a common intake passage, a cylinder providing the exhaust side a plurality of cylinder groups which are connected to different exhaust passages from each other, the influence on the intake air conditions in each of the plurality of cylinder groups in the abnormality detecting apparatus applied to an internal combustion engine having a accessory device for each group, for each of the cylinder groups, intake pressure or intake air amount of the intake passage, an exhaust temperature of the exhaust passage, at least one detection of the air-fuel ratio An abnormality determination unit that determines whether there is an abnormality in the attached device based on whether a difference between detection values of the same type detected for each cylinder group detected by the detection unit exceeds a limit value ; When the abnormality determining means determines abnormality of the accessory device, the fuel injection amount, the opening timing of the intake valve, or the intake valve of the cylinder group corresponding to the accessory device determined to be abnormal among the plurality of cylinder groups. Riff And protection operation execution means for limiting at least one of the amount, but with a (claim 1).

According to abnormal detecting device of the present invention, if any of any abnormality occurring intake state accessory device corresponding to the cylinder group is not controlled properly, the intake air amount of the cylinder that influence belonging to the cylinder group As a result, the intake air amount varies among the cylinders, and the influence also appears in the exhaust gas flow rate in the exhaust passage. On the other hand, if the intake passages are common between the cylinder groups, the fuel injection amount is controlled to be equal to each other on the assumption that the same air is sucked into each cylinder. Therefore, in the state where the abnormality of the accessory device is biased in any cylinder group, the air-fuel ratio relating to the cylinder group in which the abnormality has occurred becomes different from the other cylinder groups, and the air-fuel ratio detected in the exhaust passage is different. A difference corresponding to the difference in intake air amount appears in the fuel ratio. Moreover, since a difference also occurs in the combustion temperature due to the difference in air-fuel ratio, a difference also appears in the exhaust temperature of the exhaust passage. Furthermore, even when the fuel injection control shifts to the no fuel injection state, if there is a difference in the flow rate of the exhaust gas, a difference occurs in the degree of decrease in the exhaust temperature after the shift to the no fuel injection state. By determining whether or not there is a difference in exhaust temperature or air-fuel ratio, it is possible to determine whether or not an abnormality has occurred in each accessory device. The same applies to the intake pressure or intake air amount in the intake passage for each cylinder group. Since the exhaust temperature, air-fuel ratio, intake pressure, and intake air amount are physical quantities that are generally detected as information necessary for operation control in the internal combustion engine, it is not necessary to provide dedicated sensors for detecting abnormalities in the attached device. .

In abnormal detecting device of the present invention, the internal combustion engine further includes a turbocharger provided in front Symbol exhaust passage each, the detecting device, as a detection value of each of the cylinder groups, after supercharging by the turbocharger May be detected for each turbocharger (claim 2).

There when some abnormality in accessory device corresponding to the cylinder group of Zureka occurs in the intake gas state is not controlled properly, the flow rate of the exhaust gas between reflected to the exhaust gas flow rate cylinder group of the influence exhaust passage There is a difference. If the flow rate of the exhaust gas is different, there is a difference in the supercharging effect by the turbocharger accordingly. The influence also appears in the intake pressure or intake air amount for each turbocharger after supercharging by the turbocharger, which is detected by the detection means. Accordingly , it is possible to determine whether or not an abnormality has occurred in each attached device .

  In each abnormality detection device of the present invention, the attached device affects the intake state in each of the plurality of cylinder groups, and may be provided for each cylinder group. It is not limited to a device provided for the purpose of adjusting the above, but also includes a device that influences the intake state as a result of its operation and state. Therefore, by changing the valve operating characteristics of the supercharger, intake valve or exhaust valve that changes the supercharging pressure or supercharging amount of the intake air using the exhaust energy from the exhaust passage for each cylinder group, etc. A variable valve mechanism that changes the amount of air, an intake air flow control valve that controls the intake air flow (swirl flow and tumble flow) in the cylinder by changing the characteristics of the intake port, and the amount of fresh air in the intake air by changing the EGR gas amount The EGR valve that changes the ratio of the exhaust gas is not only included in the concept of the accessory device, but also, for example, an exhaust purification device such as a filter provided in the exhaust passage, a catalyst, an EGR cooler provided in the EGR passage for each exhaust passage, etc. As long as these clogging conditions affect the intake state, they are included in the concept of the accessory device.

  According to the present invention, the presence or absence of an abnormality in the attached device is determined by referring to the intake air amount, intake pressure, exhaust temperature, or air-fuel ratio that is generally detected as information necessary for operation control of the internal combustion engine. There is no need to provide dedicated sensors for detecting abnormalities in attached devices. Therefore, the configuration of the abnormality detection device can be simplified, and the cost can be reduced by reducing the number of parts.

  FIG. 1 shows an example of an internal combustion engine to which the abnormality detection device of the present invention is applied. In this example, the internal combustion engine is configured as a V-type 8-cylinder diesel engine 1 in which four cylinders 3 are provided in each of the left and right banks 2L, 2R. The engine 1 is used as a power source for a vehicle such as an automobile, for example. Installed. In the engine 1, one cylinder group is configured by the cylinders 3 in the left bank 2L, and another cylinder group is configured by the cylinders 3 in the right bank 2R. In addition, # 1- # 8 attached | subjected in the figure is a cylinder number for distinguishing the cylinder 3. FIG. For example, the cylinder 3 at the upper left in the figure is identified as the cylinder 3 with cylinder number # 1.

An intake passage 4 for guiding intake air to each cylinder 3 is divided into branch paths 4L and 4R for each bank downstream of the air cleaner 5, and compressor sections 6a of turbochargers 6L and 6R are arranged on the branch paths 4L and 4R. ing. The branch passages 4L and 4R pass through the intercooler 7 downstream of the compressor unit 6a and are connected to a common intake manifold (common intake passage) 8 constituting a part of the intake passage 4. An intake pressure sensor 9a for detecting the intake pressure and an air flow meter 9b for detecting the intake air amount are provided inside the intake manifold 8 . Na us, branch passages 4L, flow meter 9c for detecting an intake air amount in each 4R, may be 9d is further provided. These air flow meters 9c and 9d function as detection means for detecting the intake air amount after supercharging by the turbochargers 6L and 6R for each of the turbochargers 6L and 6R. As such detection means, an intake pressure sensor may be provided in the branch paths 4L, 4R instead of the air flow meters 9c, 9d.

  On the other hand, the exhaust from the cylinders 3 of the banks 2L and 2R is guided to the turbine section 6b of the turbochargers 6L and 6R from the exhaust manifolds 11L and 11R of the exhaust passages 10L and 10R provided for each bank, and further to the turbine section 6b. To the downstream side. The turbochargers 6L and 6R are variable nozzle turbochargers provided with a variable nozzle (not shown) capable of adjusting the opening degree on the turbine section 6b side. The nozzle opening degree of each turbocharger 6L, 6R is controlled by the engine control unit (ECU) 12 between a fully open state and a fully closed state. However, the fully closed state is set when the exhaust flow rate is increased and the turbine speed is increased when the exhaust flow rate is low and the engine speed is low and the load is low. Passes downstream. The ECU 12 is a known computer that controls the operating state of the engine 1. For example, the ECU 12 controls the fuel injection amount from the fuel injection valve 20 provided in each cylinder 3 according to the intake pressure detected by the intake pressure sensor 9a or the intake air amount detected by the air flow meter 9b. The intake port of each cylinder 3 is branched into two in the direction in which the cylinders 3 are arranged, and one of the intake ports is provided with swirl control valves (SCV) 21L and 21R for opening and closing the intake port. By closing the SCVs 21L and 21R, an intake swirl flow is formed in the cylinder 3. The SCVs 21L and 21R are driven independently for each of the banks 2L and 2R.

  Each exhaust manifold 11L, 11R is connected to the intake manifold 8 via the EGR passages 13L, 13R for each bank. EGR coolers 14L and 14R for cooling EGR gas and EGR valves 15L and 15R for adjusting the EGR flow rate are provided in the EGR passages 13L and 13R, respectively. The opening degree of the EGR valves 15L, 15R is controlled by the ECU 12 so that an appropriate amount of EGR gas corresponding to the operating state of the engine 1 is supplied to the intake manifold 8. Although not shown, the EGR passages 13L and 13R include a bypass passage that bypasses the EGR coolers 14L and 14R and guides exhaust gas to the EGR valves 15L and 15R, respectively, and a bypass passage and the EGR coolers 14L and 14R. And a bypass valve for switching the passage path of the EGR gas between them.

  In the exhaust passages 10L and 10R downstream of the turbochargers 6L and 6R, a particulate filter (hereinafter sometimes abbreviated as a filter) 16L as exhaust purification means for collecting particulate matter (PM) in the exhaust. , 16R are provided. The filters 16L and 16R may function as NOx storage reduction catalysts by carrying NOx storage reduction substances. Fuel addition valves 17L and 17R are provided between the turbine section 6b and the filters 16L and 16R as fuel supply means for supplying fuel to the exhaust passages 10L and 10R. Fuel addition by the fuel addition valves 17L and 17R is performed under the control of the ECU 12 for regeneration processing and PM oxidation processing for sulfur poisoning of the filters 16L and 16R. Air-fuel ratio sensors 18L and 18R and exhaust temperature sensors 19L and 19R are provided downstream of the filters 16L and 16R. The outputs of these sensors are input to the ECU 12. Although a silencer or the like is provided further downstream of the exhaust passages 10L and 10R, the illustration thereof is omitted. The air-fuel ratio sensors 18L and 18R only need to output signals corresponding to the air-fuel ratio. The air-fuel ratio may be detected using a sensor that detects the oxygen concentration. The outputs of the intake pressure sensor 9a and the air flow meters 9b to 9d described above are similarly input to the ECU 12.

  In the engine 1 configured as described above, the auxiliary devices for each cylinder group that affect the intake state in the cylinders 3 of the banks 2L and 2R are variable nozzles of the turbochargers 6L and 6R, SCVs 21L, 21R, and EGR valves. There are 15L and 15R. The filters 16L and 16R and the EGR coolers 14L and 14R are also a kind of accessory device in that their clogging (airflow resistance) affects the intake state of the cylinder 3. According to the present invention, it is possible to detect abnormalities in these attached devices using the sensors 9a to 9d, 18L, 18R, 19L, and 19R described above. Embodiments relating to abnormality detection will be described below.

(First reference example )
First, a first reference example related to the present invention will be described prior to the description of the embodiment relating to abnormality detection. In this reference example , the abnormality of the nozzles of the turbochargers 6L and 6R or the filters 16L and 16R is detected using the supercharging pressure detected by the intake pressure sensor 9a or the intake air amount detected by the air flow meter 9b.

  In FIG. 1, the variable pressure nozzle of the turbocharger 6R in the right bank 2R is fixed in the fully closed state, that is, fixed in the fully closed state and becomes inoperable to the open side, or detected by the intake pressure sensor 9a when the filter 16R is excessively clogged. An example of the change in the intake pressure is shown in FIG. 2A, and an example of the change in the intake air amount detected by the air flow meter 9b is shown in FIG. For comparison, examples of the intake pressure and the intake air amount detected at the normal time when these abnormalities have not occurred are indicated by a one-dot chain line in each figure. 2A and 2B, the detection target period is 720 ° CA (meaning the crank angle), and the intake order of the cylinder 3 during that period is as shown in the lower part of each figure. .

  When the variable nozzle of the turbocharger 6R is fully closed or the filter 16R is clogged excessively, the exhaust manifold 11R is inhaled when the cylinder 3 (# 2, # 4, # 6, # 8) belonging to the right bank 2R is inhaled. As a result, the remaining gas pressure of the cylinder 3 increases, and as a result, the intake efficiency decreases, the intake pressure of the intake manifold 8 increases from the normal time, and the intake air amount decreases from the normal time. . Therefore, the fluctuation range of the intake pressure or intake air amount in the intake manifold 8, that is, the difference between the maximum value and the minimum value is the difference between the maximum value and the minimum value of the intake pressure or intake air amount at normal time (normal value). By comparing, it is possible to determine whether the variable nozzles of the turbochargers 6L and 6R are fully closed or whether the filters 16L and 16R are clogged excessively.

  FIG. 3 is a flowchart showing an abnormality detection routine for causing the ECU 12 to perform abnormality detection based on the principle described above. In FIG. 3, abnormality detection is performed using the intake pressure sensor 9a. In the abnormality detection routine of FIG. 3, the ECU 12 first determines in step S1 whether or not a precondition for abnormality detection is satisfied. Preconditions in this case are that the engine speed and load exceeding a predetermined level continue for a predetermined period, and the opening command value for the variable nozzles of the turbochargers 6L and 6R is a predetermined opening or more, that is, in a fully closed state. On the other hand, it is required that the ECU 12 gives an instruction to open the nozzle beyond a predetermined amount. The former requirement (requirement of operation state) is that the engine pressure and load are not in an operation state where the engine speed and load have increased to some extent, and fluctuations that can detect an abnormality do not appear in the intake pressure and intake air amount. This is required because the intake pressure and the intake air amount are not stable immediately after the operating state is obtained, and there is a risk of erroneous determination. The latter requirement (nozzle opening requirement) is required in order not to erroneously determine that the fully closed state based on the command from the ECU 12 is abnormal. In order to determine whether or not it has continued for a predetermined period in step S1, for example, a history of determination results of requirements regarding engine speed and load is stored in the process of repeatedly executing the routine of FIG. What is necessary is just to judge whether the requirement was continuously affirmed by the frequency | count to do. In addition to this, in parallel with the routine of FIG. 3, a process of measuring the engine speed of a predetermined level or more and the duration of the load with a timer may be executed.

  The ECU 12 ends the abnormality detection routine if the precondition is not satisfied, and proceeds to step S2 if the precondition is satisfied. In step S2, the intake pressure sensor 9a detects the intake pressure while the crankshaft of the engine 1 rotates 720 °. In the subsequent step S3, it is determined whether or not the difference between the detected maximum value and minimum value of the intake pressure is greater than a predetermined limit value. Assuming that the nozzles of the turbochargers 6L and 6R and the filters 16L and 16R are normal, the limit value assumes the worst operating condition in which the fluctuation range of the intake pressure and the intake air amount is the largest, and the worst operating condition It is necessary to set so that the difference between the maximum value and the minimum value of the intake pressure and the intake air amount detected in step 5 is not erroneously determined as abnormal. Therefore, the limit value may be set to a somewhat large value that allows for a control error with respect to the difference between the maximum value and the minimum value under the worst operating conditions.

  If the difference between the maximum value and the minimum value does not exceed the limit value in step S3, the process proceeds to step S44, where it is determined that the turbochargers 6L, 6R and the filters 16L, 16R are normal, and then the routine ends. On the other hand, if the difference exceeds the limit value in step S3, the process proceeds to step S5, and it is determined that the nozzles of the turbocharger 6L or 6R are fully closed or the filters 16L and 16R are clogged excessively. In the subsequent step S6, the cylinder 3 in which the maximum value for the intake pressure has occurred is determined. The correspondence relationship between the crank angle when the predetermined crank position is used as a reference and the intake timing of each cylinder 3 can be specified in advance from the intake order between the cylinders 3. On the other hand, the ECU 12 functions as a cylinder discriminating unit that discriminates the cylinder 3 at the explosion timing using a crank angle signal detected by a crank angle sensor (not shown). Therefore, by using the function of the cylinder discriminating means, it is possible to determine the crank angle at which the intake pressure has recorded the maximum value and to determine which cylinder 3 has the maximum value generated by the ECU 12. it can.

  In the subsequent step S7, by determining the bank 2L or 2R to which the cylinder 3 with the maximum intake pressure belongs, the turbochargers 6L and 6R or the filters 16L and 16R corresponding to the left and right banks 2L or 2R are determined. In step S8, the engine protection operation is performed on the bank 2L or 2R on the side where the abnormality has occurred. As the engine protection operation, for example, the fuel injection amount can be limited with respect to the bank 2L or 2R on which the abnormality has occurred, and the intake valve opening timing and the lift amount can be limited in order to prevent an excessive increase in the intake pressure. After the engine protection operation is performed, the abnormality detection routine is finished.

  In the routine of FIG. 3, the difference between the maximum value and the minimum value of the intake air amount detected by the air flow meter 9b instead of the intake pressure detected by the intake pressure sensor 9a is compared with a limit value to determine whether or not an abnormality has occurred. You may judge. In this case, it is only necessary to determine the cylinder in which the intake air amount has recorded the minimum value in step S6.

( Second reference example )
Next, a second reference example regarding abnormality detection will be described. In the second reference example , the abnormality of the nozzles of the turbochargers 6L and 6R is detected using the exhaust temperatures of the exhaust passages 10L and 10R detected by the exhaust temperature sensors 19L and 19R provided in the exhaust passages 10L and 10R. To do. If there is a change in operating conditions such that the vehicle starts accelerating or driving at a constant speed and the vehicle starts accelerating or decelerating, the fuel injection control is in the no-injection state (the fuel injection is (Stopped state) may occur. When such operating conditions are changed, the exhaust temperature of the engine 1 is lower than that before the transition because no combustion occurs in the cylinder 3. At this time, the degree of decrease in the exhaust temperature varies depending on the flow rate of the exhaust gas, and the decrease in the exhaust temperature is delayed as the flow rate of the exhaust gas is smaller.

  On the other hand, when the variable nozzle is fully closed and stuck in either one of the turbochargers 6L or 6R, the flow rate of the exhaust gas guided downstream of the abnormal turbocharger 6L or 6R where the fully closed and stuck is generated is This is less than the flow rate of the exhaust gas guided downstream of the turbocharger 6R or 6L on the normal side where the fully closed adhering has not occurred.

  Therefore, as shown in FIG. 4 as an example, the operating condition of the engine 1 is changed at time t1 to switch to the no fuel injection state, and accordingly, the predetermined opening degree with respect to the variable nozzles of the turbochargers 6L and 6R. For example, when an operation instruction to the fully open state is given, if any one of the turbochargers 6L or 6R is abnormally fully closed, the exhaust temperature sensor 19L or 19R on the abnormal side detects that abnormality. The exhaust temperature decreases with a delay from the exhaust temperature detected by the normal exhaust temperature sensor 19R or 19L. Therefore, the elapsed time S at which the difference in exhaust temperature appears sufficiently is examined in advance, and an appropriate judgment value is set between the exhaust temperatures detected by both the exhaust temperature sensors 19L and 19R at the time t2 when the elapsed time S has elapsed. Then, it can be determined whether or not there is a fully-closed sticking abnormality of the variable nozzle based on whether or not the exhaust temperature when the time S has elapsed from the change of the operating condition is higher than the determination value.

FIG. 5 is a flowchart showing an abnormality detection routine for causing the ECU 12 to perform abnormality detection based on the above-described principle. In the abnormality detection routine, ECU 12 first prerequisite when the abnormality detection in Step S 11 it is determined whether or not satisfied. As preconditions in this case, it is required that the exhaust temperature detected by the exhaust temperature sensors 19L and 19R is equal to or higher than a predetermined value, and the intake air amount detected by the air flow meter 9b is higher than a predetermined value. Has been. If the exhaust temperature is too low at the start of judgment, the difference in exhaust temperature drop may not appear clearly, and if the intake air amount is insufficient, the exhaust temperature lowering effect in the non-injection state may not appear clearly. Because there is.

  The ECU 12 ends the abnormality detection routine if the precondition is not satisfied, and proceeds to step S12 if the precondition is satisfied. In step S12, it is determined whether or not the operating condition of the engine 1 has been changed to accompany the transition to the no fuel injection state. If not changed, the abnormality detection routine is terminated. On the other hand, if the operating condition has been changed, the process proceeds to step S13, and a determination value used in the current abnormality detection routine is calculated based on the exhaust temperature, the intake air amount, and the outside air temperature before the operating condition is changed. The relationship between these physical quantities can be obtained experimentally in advance and stored in the storage device of the ECU 12 as a function or a map. In the subsequent step S14, a fully open instruction is given to the variable nozzles of the turbochargers 6L, 6R, and the exhaust temperature at the time when a predetermined time S has elapsed since the operation condition was changed in the subsequent step S15 is determined by the exhaust temperature sensors 19L, 19R. To detect.

In the next step S16, it is determined whether any one of the exhaust temperatures detected by the left and right exhaust temperature sensors 19L and 19R exceeds a determination value (calculated in step S13). If the exhaust temperature exceeding the determination value is not detected, the process proceeds to step S17, where it is determined that the variable nozzle is normal, and then the routine ends. On the other hand, when the exhaust temperature exceeding the determination value is detected in step S16, the process proceeds to step S18, and it is determined that the opening degree of the variable nozzle related to the bank in which the temperature higher than the determination value is detected is abnormal. Thereafter, the engine protection operation is performed on the bank 2L or 2R on the side determined to be abnormal in step S19. The engine protection operation may be the same as in the first reference example . After the engine protection operation is performed, the abnormality detection routine is finished.

(Embodiment of the present invention )
Next, an embodiment of the present invention relating to abnormality detection will be described. In this embodiment, the air-fuel ratios detected by the air-fuel ratio sensors 18L and 18R provided in the exhaust passages 10L and 10R, the exhaust temperatures of the exhaust passages 10L and 10R detected by the exhaust temperature sensors 19L and 19R, or the intake passage 4 Abnormalities in the SCVs 21L and 21R are detected using the difference between the left and right banks 2L and 2R in the air amount detected by the airflow meters 9c and 9d provided in the branch paths 4L and 4R. When the SCV 21L or 21R is fully closed and fixed in any one of the banks 2L and 2R, the abnormal side bank in which the fully closed fixation has occurred is compared with the normal bank 2R or 2L in which the fully closed fixation has not occurred. Intake air volume decreases.

  On the other hand, since the fuel injection amount is controlled equally in each of the banks 2L and 2R, the air-fuel ratio detected by the air-fuel ratio sensors 18L and 18R is smaller on the abnormal side than the normal side, that is, on the rich side where the fuel amount is large. It becomes like this. Further, since the intake air amount decreases on the abnormal side, the excess ratio of air in the cylinder 3 becomes lower than that on the normal side, and as a result, the exhaust temperature detected by the exhaust temperature sensors 19L and 19R is normal on the abnormal side. The value is higher than the side. Further, when the intake air amount decreases on the abnormal side, the flow rate of exhaust gas guided to the abnormal turbocharger 6L or 6R is reduced more than that on the normal side, and as a result, the excess air flow caused by the abnormal turbocharger 6L or 6R increases. The supply effect is lower than that on the normal side, and the amount of air detected by the airflow meters 9c and 9d becomes smaller on the abnormal side than on the normal side.

  FIGS. 6A to 6C show examples of variations in the air-fuel ratio (AF), the exhaust temperature, and the air amount at the time of SCV full open fixing, in comparison with normal values without SCV fixing. In FIGS. 6A to 6C, “standard” indicates the air-fuel ratio of each bank 2L, 2R when there is no factor causing a difference in the air-fuel ratio between the left and right banks 2L, 2R. “Worst variation” is that the SCVs 21L and 21R are both normal, but the operating conditions in which the difference in air-fuel ratio between the left and right banks 2L and 2R is the largest are set. The fuel ratio is shown. As is apparent from FIGS. 6A to 6C, when the SCVs 21L and 21R are fully closed, the difference in air-fuel ratio and the like is larger than in the case of “variation worst”. Therefore, it is possible to determine whether the SCV 21L or 21R is fully closed depending on whether or not the difference in air-fuel ratio between the left and right banks 2L and 2R is larger than in the case of “the worst dispersion”.

  FIG. 7 is a flowchart showing an abnormality detection routine for causing the ECU 12 to execute abnormality detection based on the principle described above. In this abnormality detection routine, the ECU 12 first determines in step S21 whether a precondition for abnormality detection is satisfied. As preconditions in this case, a full open command is given to the SCVs 21L and 21R, a full close command is given to the EGR valves 15L and 15R, and the engine speed is a predetermined value or more. And that the air-fuel ratio is not more than a predetermined value. The fully open command for the SCVs 21L and 21R is a requirement necessary for determining whether or not these valves do not operate from the fully closed state against the command. The fully closed requirement for the EGR valves 15L and 15R is the EGR valve 15L, This is required to eliminate the influence of 15R on the air-fuel ratio between the banks 2L and 2R. In addition, the requirement regarding the engine speed is that if the engine speed has not increased to some extent, the absolute value of the exhaust gas flow rate is small, and even if the fully closed sticking occurs, a clear difference in air-fuel ratio or the like may not occur. Is required. Further, the requirement regarding the air-fuel ratio is required because if the fuel injection amount is too small, the influence of the fully-closed fixation of the SCV 21L or 21R on the air-fuel ratio or the exhaust temperature is small and it becomes difficult to detect an abnormality.

  The ECU 12 ends the abnormality detection routine if the precondition is not satisfied, and proceeds to step S22 if the precondition is satisfied. In step S22, the difference between the left and right banks 2L, 2R of the air-fuel ratio detected by the air-fuel ratio sensors 18L, 18R, the exhaust temperature detected by the exhaust temperature sensors 19L, 19R, or the intake air amount detected by the airflow meters 9c, 9d is calculated. To detect. In the subsequent step S23, it is determined whether or not the difference between the left and right banks 2L, 2R such as the air-fuel ratio exceeds a limit value. The limit value must be set so that the “worst dispersion” shown in FIGS. 6A to 6C is not erroneously determined as abnormal. For example, a value obtained by adding a control error to the difference between the left and right at the “worst case variation” may be set as the limit value.

If the limit value is not exceeded in step S23, the process proceeds to step S24, where it is determined that the SCVs 21L and 21R are normal, and then the routine is finished. On the other hand, if the limit value is exceeded in step S23, the process proceeds to step S25, and it is determined that the fully closed adhering has occurred in the SCV 21L or 21R. Thereafter, an engine protection operation is performed in step S26. The engine protection operation may be the same as in the first reference example , but when it is not determined which side of the SCV 21L, 21R, the protection operation may be performed for both banks 2L, 2R. After the engine protection operation is performed, the abnormality detection routine is finished. In the present embodiment, it may be further determined which of the SCVs 21L and 21R is fully closed and fixed from the magnitude relationship such as the air-fuel ratio.

( Third reference example)
Next, a third reference example regarding abnormality detection will be described. In this reference example, the abnormality of the SCVs 21L and 21R is detected by using the intake pressure detected by the intake pressure sensor 9a provided in the intake manifold 8 or the intake air amount detected by the air flow meter 9b.

  8A and 8B show the intake pressure and the intake air amount detected by the intake pressure sensor 9a and the air flow meter 9b between 720 ° CA when at least one of the SCV 21L or 21R is fully closed and fixed. The solid line (at the time of abnormality), and the intake pressure and the amount of intake air when not fully closed and fixed are illustrated by the alternate long and short dash line (at the time of normal). The order of explosion between the cylinders 3 in the V-type engine 1 realizes a so-called unequal interval explosion in which explosions continue in some cylinders 3 of the left and right banks 2L and 2R, which are generally advantageous for suppressing engine vibration. Is set as follows. For example, in the V-type 8-cylinder engine 1 shown in FIG. 1, the explosion interval is 90 ° CA. Therefore, if an equidistant explosion that alternately causes explosions in the left and right banks 2L, 2R is adopted, each bank 2L, In 2R, explosions occur at intervals of 180 ° CA. However, according to the intake order shown in FIG. 8 (a), the cylinder numbers # 5 to # 7 and # 8 to # 4 continue the explosion at 90 ° CA intervals in the same bank. By providing such a part, unequal interval explosion is realized.

  On the other hand, if the intake manifold 8 is common between the banks 2L and 2R, the pulsation of the intake pressure and intake air amount should be repeated at 90 ° CA intervals, and the maximum and minimum values of the intake pressure and intake air amount As shown in FIG. 8A and FIG. 8B, only the influence of the pulsation of intake should appear. However, for example, if the SCV 21L of the left bank 2L is fully closed, the intake air amount decreases and the intake pressure increases after the explosion continues from # 5 to # 7 and # 1 in the left bank 2L. When the explosion continues in the right bank 2R # 8 → # 4, the intake air amount increases and the intake pressure decreases. Therefore, the difference between the maximum value and the minimum value of the intake pressure and the intake air amount at the time of abnormality is larger than that at the normal time. Therefore, a limit value is set in advance for the difference between the maximum value and the minimum value of the intake pressure or the intake air amount, and whether or not the SCV 21L or 21R is stuck abnormally can be determined based on whether or not the difference exceeds the limit value. .

  FIG. 9 is a flowchart showing an abnormality detection routine for causing the ECU 12 to perform abnormality detection based on the above-described principle. In this abnormality detection routine, the ECU 12 first determines in step S31 whether a precondition for detecting an abnormality is satisfied. As preconditions in this case, a full open command is given to the SCVs 21L and 21R, a full close command is given to the EGR valves 15L and 15R, and the engine speed is a predetermined value or more. It is required to be. The fully open command for the SCVs 21L and 21R is a requirement necessary for determining whether or not these valves do not operate from the fully closed state against the command. The fully closed requirement for the EGR valves 15L and 15R is the EGR valve 15L, This is required to eliminate the influence of 15R on the air-fuel ratio between the banks 2L and 2R. In addition, the requirement regarding the engine speed is that if the engine speed has not increased to some extent, the absolute value of the exhaust gas flow rate is small, and even if the fully closed sticking occurs, a clear difference in air-fuel ratio or the like may not occur. Is required.

  The ECU 12 ends the abnormality detection routine if the precondition is not satisfied, and proceeds to step S32 if the precondition is satisfied. In step S32, the intake pressure or intake air amount between 720 ° CA in the intake manifold 8 is detected by the intake pressure sensor 9a or the air flow meter 9b. In the subsequent step S33, it is determined whether or not the difference between the detected maximum value of intake pressure or intake air amount and the minimum value exceeds a limit value. The limit value needs to function as a threshold value so that the difference between the normal maximum value and the minimum value in FIG. 8 is not erroneously determined as abnormal. For example, for the difference between the normal maximum value and the minimum value, Set the value to which the control error is added.

If the limit value is not exceeded in step S33, the process proceeds to step S34 to determine that the SCVs 21L and 21R are normal, and then the routine is finished. On the other hand, if the limit value is exceeded in step S33, the process proceeds to step S35, and it is determined that the fully closed adhering has occurred in the SCV 21L or 21R. Thereafter, an engine protection operation is performed in step S36. The engine protection operation may be the same as in the first reference example. However, when it is not determined which side of the SCV 21L, 21R is abnormal, the protection operation may be performed for both banks 2L, 2R. After the engine protection operation is performed, the abnormality detection routine is finished. In this reference example , from the relationship between the crank angle and the explosion order (intake order) when the maximum value and the minimum value are generated, it is further determined which of the SCVs 21L and 21R is fully closed. It may be determined.

( Fourth reference example)
Next, a fourth reference example regarding abnormality detection will be described. In this reference example, abnormalities in the EGR valves 15L and 15R or the EGR coolers 14L and 14R are detected by using the intake pressure detected by the intake pressure sensor 9a provided in the intake manifold 8 or the intake air amount detected by the air flow meter 9b. To detect.

  In FIG. 1, for example, when the EGR valve 15L of the left bank 2L is fully closed or excessively clogged in the EGR cooler 14L, an example of a change in the intake pressure detected by the intake pressure sensor 9a is shown in FIG. An example of the change in the intake air amount detected by the air flow meter 9b is shown in FIG. For comparison, examples of the intake pressure and the intake air amount detected at the normal time when these abnormalities have not occurred are indicated by a one-dot chain line in each figure. 10 and 11, the detection target period is 720 ° CA (meaning a crank angle), and the exhaust order of the cylinder 3 during that period is as shown in the lower part of each figure.

  If EGR gas is introduced into the intake manifold 8, the intake pressure rises and the amount of fresh air introduced from the intake passage 4 decreases. However, if only one of the EGR passages 13L (or 13R) is clogged, EGR Variations in the intake pressure and the fresh air amount accompanying the change in the gas amount increase. In particular, in the V-type engine 1 in which the above-described unequal interval explosion is performed, the EGR valve 15L is fully closed and fixed in the left bank 2L or excessive clogging occurs in the EGR cooler 14L, and the EGR in the right bank 2R. If there is no abnormality in the valve 15R and the EGR cooler 14R, a large amount of EGR gas is introduced into the intake manifold 8 when exhausting is continued in the right bank 2R (# 8 → # 4) as shown in FIG. As a result, the intake pressure rises greatly and the maximum value is recorded. At the same time, the intake air amount (in this case, the fresh air amount) is greatly reduced and the minimum value is recorded. Further, when exhaust is continuously performed in the left bank 2L (# 5 → # 7), no or almost no EGR gas is introduced into the intake manifold 8, and the intake pressure of the intake manifold 8 is greatly reduced to record the minimum value. However, the intake air volume increases significantly and the maximum value is recorded. The difference between the maximum value and the minimum value is sufficiently larger than that of the normal value. Therefore, by comparing the difference between the maximum value and the minimum value of the intake pressure or intake air amount in the intake manifold 8 with the difference (normal value) between the maximum value and the minimum value of the intake pressure or intake air amount at normal time. The presence or absence of abnormality can be determined.

  FIG. 12 is a flowchart showing an abnormality detection routine for causing the ECU 12 to detect abnormality of the EGR valves 15L and 15R based on the principle described above. In this abnormality detection routine, the ECU 12 first determines in step S41 whether or not a precondition for abnormality detection is satisfied. As a precondition in this case, an operation command to a predetermined opening, for example, a fully opened state is given to the EGR valves 15L, 15R, and bypassing the EGR coolers 14L, 14R by bypassing in the EGR passages 13L, 13R It is required that the exhaust gas is guided to the passage and that the intake air amount to the intake manifold 8 is stable for a predetermined time. The opening degree commands for the EGR valves 15L and 15R are requirements necessary for determining whether these valves do not operate from the fully closed state against the commands. The bypass of the EGR coolers 14L and 14R is required to eliminate the influence of the clogging condition of the EGR coolers 14L and 14R on the intake pressure and the like. In addition, the requirements regarding the intake air amount are required to avoid erroneous detection by making a determination while avoiding an operating state in which the intake pressure or the intake air amount fluctuates.

  The ECU 12 ends the abnormality detection routine if the precondition is not satisfied, and proceeds to step S42 if the precondition is satisfied. In step S42, the intake pressure or intake air amount between 720 ° CA in the intake manifold 8 is detected by the intake pressure sensor 9a or the air flow meter 9b. In the next step S43, the pulsation width (maximum value and minimum value) of the intake pressure or the intake air amount in the normal state (the state where the EGR valves 15L and 15R are not fully closed) is determined from the rotation speed of the engine 1 and the intake air amount. Difference) is calculated as a limit value for determination. This limit value assumes the worst operating condition in which the pulsation width of the intake pressure and the intake air amount becomes maximum when the EGR valves 15L and 15R are normal, and the pulsation of the intake pressure or intake air amount recorded in the operation condition It is necessary to function as a threshold value that does not erroneously determine that the width is abnormal. For example, a value obtained by adding a predetermined control error to the pulsation width in the worst operating condition may be set as the limit value. Further, the correspondence relationship between the engine speed, the intake air amount, and the pulsation width can be experimentally obtained in advance and stored in the storage device of the ECU 12 as a function or a map. In step S43, the limit value may be calculated with reference to the function.

  In the next step S44, it is determined whether or not the difference between the maximum value and the minimum value of the detected intake pressure or intake air amount exceeds a limit value. If it does not exceed the limit value, the process proceeds to step S45, where it is determined that the EGR valves 15L, 15R are normal, and then the routine ends. On the other hand, if the limit value is exceeded in step S44, the process proceeds to step S46, where it is determined that the EGR valve 15L or 15R is fully closed and the routine is ended. Further, it is further determined which of the EGR valves 15L and 15R is fully closed from the relationship between the crank angle and the exhaust order when the maximum value and the minimum value of the intake pressure or intake air amount are generated. May be.

  On the other hand, FIG. 13 is a flowchart showing an abnormality detection routine for causing the ECU 12 to detect abnormality of the EGR coolers 14L and 14R based on the principle described above. This abnormality detection routine is executed after the routine of FIG. 12, and the ECU 12 determines whether or not a precondition for detecting the abnormality is satisfied in step S51. As preconditions in this case, it is determined that the EGR valves 15L and 15R are normal by the abnormality detection routine of FIG. 12, and an operation command to a predetermined opening, for example, a fully open state is given to the EGR valves 15L and 15R. That the exhaust gas is guided without bypassing the EGR coolers 14L and 14R in the EGR passages 13L and 13R, and that the intake air amount to the intake manifold 8 is stable for a predetermined time. It is requested.

  The reason why the EGR valves 15L and 15R are required to be normal is that, if the EGR portions 15L and 15R are abnormal, the influence of fluctuations in the EGR gas flow rate on the intake pressure and intake air amount of the intake manifold 8 This is because the influence of the EGR coolers 14L and 14R cannot be determined. In order to determine the influence of clogging of the EGR coolers 14L and 14R on the intake pressure and intake air amount of the intake manifold 8 from the EGR passages 13L and 13R, the requirements regarding the opening degree commands for the EGR valves 15L and 15R are as follows. This is required because a certain amount of EGR gas needs to be introduced. The requirements regarding the bypass are requirements necessary to determine the influence of clogging of the EGR coolers 14L and 14R. The bypass of the EGR coolers 14L and 14R is required to eliminate the influence of the clogging condition of the EGR coolers 14L and 14R on the intake pressure and the like. The requirement regarding the intake air amount is required to prevent erroneous detection by making a determination while avoiding an operating state in which the intake pressure or the intake air amount fluctuates.

  The ECU 12 ends the abnormality detection routine if the precondition is not satisfied, and proceeds to step S52 if the precondition is satisfied. In step S52, the intake pressure or intake air amount between 720 ° CA in the intake manifold 8 is detected by the intake pressure sensor 9a or the air flow meter 9b. In the next step S53, the intake pressure or intake air amount in the normal state (the EGR valves 15L, 15R are normal and the EGR coolers 14L, 14R are not clogged) is determined from the rotational speed of the engine 1 and the intake air amount. The pulsation width (the difference between the maximum value and the minimum value) is calculated as a limit value for determination. This limit value assumes the worst operating condition in which the pulsation width of the intake pressure and the intake air amount is maximized when the EGR valves 15L and 15R are normal and the EGR coolers 14L and 14R are clogged. The pulsation width of the intake pressure or intake air amount recorded under the condition must be made to function as a threshold value so that it is not erroneously determined as abnormal. For example, a value obtained by adding a predetermined control error to the pulsation width in the worst operating condition may be set as the limit value. Further, the correspondence relationship between the engine speed, the intake air amount, and the pulsation width can be experimentally obtained in advance and stored in the storage device of the ECU 12 as a function or a map. In step S53, the limit value may be calculated with reference to the function.

  In the next step S54, it is determined whether or not the difference between the maximum value and the minimum value of the detected intake pressure or intake air amount exceeds a limit value. If it does not exceed the limit value, the process proceeds to step S55, where it is determined that the EGR coolers 14L, 14R are normal, and then the routine ends. On the other hand, if the limit value is exceeded in step S54, the process proceeds to step S56, where it is determined that the EGR cooler 14L or 14R is clogged, and then the routine ends. Further, it is further determined which of the EGR coolers 14L and 14R is excessively clogged from the relationship between the crank angle and the exhaust order when the maximum value and the minimum value of the intake pressure or intake air amount are generated. May be.

In the fourth reference example, the following changes are possible. First, if the opening command for the EGR valves 15L and 15R is changed to require that it is in the fully closed state in the precondition of step S41 in FIG. 12, the sticking abnormality in the fully opened position or the intermediate position of the EGR valves 15L and 15R. Can be detected. Of course, the engine protection operation may be performed when an abnormality is detected in the EGR valves 15L and 15R or the EGR coolers 14L and 14R in the fourth reference example .

  Further, in FIG. 12 and FIG. 13, the intake pressure or the intake air amount between 720 ° CA is detected in steps S42 and S52, respectively. However, the V-type engine 1 of FIG. As is clear from FIGS. 10 and 11, when the EGR valves 15L and 15R and the EGR coolers 14L and 14R are abnormal, the intake pressure and the intake air amount are maximized when exhaust is continuously performed in the cylinder 3 in the same bank. There is a tendency to record values and minimum values. Therefore, in view of the specific crank angle at which these maximum and minimum values occur, that is, the explosion order (exhaust order) between the cylinders 3, only in the specific crank angle range that can give the maximum or minimum value when the EGR system is abnormal. The intake pressure or the intake air amount may be detected. An example of an abnormality detection routine for performing such detection is shown in FIGS. In these drawings, the same reference numerals are assigned to the same processing portions as those in the routine of FIG.

  In the abnormality detection routine of FIG. 14, the intake pressure or intake air amount at a specific crank angle is detected in step S42A, and the maximum and minimum values detected at that time are used in the determination in step S54. In the abnormality detection routine of FIG. 15, the intake pressure or intake air amount at a specific crank angle is detected in step S52A, and the maximum value and minimum value detected at that time are used in the determination in step S64. . In FIG. 14, step S47 is added as a process after the determination of the fully closed fixation, and step S57 is added as a process after the determination of excessive clogging in FIG. 15, and the maximum and minimum values of the intake pressure or intake air amount and the exhaust gas are added. The bank on the abnormal side (the side on which full closure or excessive clogging occurs) is determined from the correspondence with the order. That is, FIGS. 10 and 11 show examples in which an abnormality has occurred in the right bank 2R, but when an abnormality has occurred in the left bank 2L, the crank angle that gives the maximum value and the crank that gives the minimum value are shown. Since the angle is interchanged, if the magnitude relationship between the intake pressure and the intake air amount detected at the specific crank angle described above is compared with each other in these steps S47 and S57, there is an abnormality in any bank 2L or 2R. It can be determined whether it has occurred. Such a determination can also be applied to the cases of FIGS.

The present invention is not limited to the embodiments described above, and can be implemented in various forms. For example, the internal combustion engine to which the present invention is applied is not limited to a V-type engine, and any layout such as a horizontally opposed type or a series type may be used as long as each of a plurality of cylinder groups is connected to different exhaust passages. It is applicable. Further, it is sufficient that at least one cylinder is included in one cylinder group.

The figure which shows an example of the internal combustion engine to which the abnormality detection apparatus of this invention is applied. The figure which shows the fluctuation | variation of the intake pressure and intake air amount for demonstrating the detection principle in the 1st reference example regarding abnormality detection. The figure which shows the abnormality detection routine which ECU performs in the 1st reference example . The figure which shows the fluctuation | variation of the exhaust temperature for demonstrating the detection principle in the 2nd reference example regarding abnormality detection. The figure which shows the abnormality detection routine which ECU performs in the 2nd reference example . The figure which shows the dispersion | variation in the air fuel ratio, exhaust temperature, and intake air amount for demonstrating the detection principle in embodiment of this invention regarding abnormality detection. The flowchart which shows the abnormality detection routine which ECU performs in embodiment of this invention . The figure which shows the fluctuation | variation of the intake pressure and intake air amount for demonstrating the detection principle in the 3rd reference example regarding abnormality detection. The flowchart which shows the abnormality detection routine which ECU performs in the 3rd reference example . The figure which shows the fluctuation | variation of the intake pressure for demonstrating the detection principle in the 4th reference example regarding abnormality detection. The figure which shows the fluctuation | variation of the intake air amount for demonstrating the detection principle in the 4th reference example regarding abnormality detection. The flowchart which shows the abnormality detection routine which ECU in 4th reference example performs. 14 is a flowchart showing another abnormality detection routine executed by the ECU after execution of FIG. 12 in the fourth reference example . The flowchart which shows the modification of FIG. The flowchart which shows the modification of FIG.

Explanation of symbols

1 Diesel Engine 2L, 2R Bank 3 Cylinder 4 Intake Passage 4L, 4R Branch 5 Air Cleaner 6L, 6R Turbocharger (Attachment)
7 Intercooler 8 Intake manifold (common intake passage )
9 c, 9d airflow meter (detection means)
10L, 10R exhaust passage 11L, 11R exhaust manifold 12 engine control unit (ECU, abnormality determination hand stage)
1 8L, 18R air-fuel ratio sensor (detecting means)
19L, 19R Exhaust temperature sensor (detection means)
20 Fuel injection valve 21L, 21R Swirl control valve (SCV, attached device)

Claims (2)

Provided with a plurality of cylinder groups in which the intake side is connected to a common intake passage and the exhaust side is connected to different exhaust passages, and an attachment device for each cylinder group that affects the intake state in each of the plurality of cylinder groups In an abnormality detection device applied to an internal combustion engine,
Detecting means for detecting at least one of the intake pressure or intake air amount of the intake passage, the exhaust temperature of the exhaust passage, and the air- fuel ratio for each of the cylinder groups;
An abnormality determining means for determining whether or not there is an abnormality in the attached device based on whether or not a difference between detection values of the same type for each cylinder group detected by the detecting means exceeds a limit value ;
When the abnormality determining means determines an abnormality of the accessory device, the fuel injection amount, the opening timing of the intake valve or the intake valve for the cylinder group corresponding to the accessory device determined to be abnormal among the plurality of cylinder groups. Protective driving means for limiting at least one of the lift amounts of
An abnormality detection device for an internal combustion engine, comprising: The internal combustion engine further includes a turbocharger provided before each Symbol exhaust passage,
Said detecting means, as a detection value of each of the cylinder groups, intake pressure or after supercharging by the turbocharger abnormality detection according to claim 1, wherein the benzalkonium detecting the intake air amount for each turbocharger apparatus.

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