JP2007032364A - Intake system abnormality detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly detect abnormality of air intake system components. <P>SOLUTION: The air intake system abnormality detecting apparatus is equipped with a knock detection device 41 for detecting the value of a parameter concerning knocking and an operation parameter detection device for detecting the value of an operation parameter other than the parameter concerning knocking. The apparatus determines that the air intake components of the internal combustion engine have abnormality when a difference between the value of the parameter concerning knocking detected by the knock detection device and the value of the parameter concerning initial or past knocking in an engine operation state identical or similar to a present engine operation stat estimated on the basis of the value of the operation parameter detected by the operation parameter detection device is not smaller than a predetermined value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intake system abnormality detection device.

  In many internal combustion engines, an in-cylinder charged air amount and an EGR (exhaust gas recirculation) rate in each cylinder are estimated based on a throttle opening degree and an on-off valve characteristic of an intake valve or an exhaust valve. Control of the fuel injection amount, ignition timing, and the like is performed based on the intake air amount and the EGR rate. As a result, the air-fuel ratio of the air-fuel mixture in the combustion chamber can be controlled to the optimum air-fuel ratio for the engine operating condition at that time, and ignition is performed at the optimum ignition timing for the air-fuel ratio and the cylinder air charge amount. This makes it possible to keep fuel consumption, exhaust emissions, etc. low while increasing the output of the internal combustion engine when necessary.

  However, if the throttle opening and the on-off valve characteristics of the intake valve or exhaust valve are mechanically deformed due to deterioration over time or failure, it is impossible to accurately estimate the in-cylinder charged air amount and EGR rate in each cylinder. As a result, the air-fuel ratio and ignition timing cannot be optimally controlled. For this reason, the performance of the internal combustion engine, such as engine output, fuel consumption, and exhaust emission, is deteriorated. Therefore, abnormalities such as aged deterioration and failure of components (for example, throttle valve, intake valve or exhaust valve on-off valve mechanism) related to intake characteristics (for example, throttle opening, intake valve / exhaust valve on / off valve characteristics, etc.) When this occurs, it is necessary to detect such an abnormality.

  For this reason, there has been proposed an apparatus for detecting abnormalities such as aged deterioration and failure of components related to the intake characteristics of an internal combustion engine. For example, Patent Document 1 discloses an abnormality detection device that determines abnormality of a variable valve timing device. In this abnormality detection device, the vibration level of the internal combustion engine is detected, and when the detected vibration level is not a predetermined vibration level, the valve overlap period is lengthened, and the overlap period is increased in spite of the lengthening the overlap period. When the vibration level does not change before and after the change, it is determined that the variable valve timing device is abnormal.

JP-A-5-106472 JP-A-63-239351 JP-A-3-267547

  In the abnormality detection device described in Patent Document 1, it is necessary to detect the vibration level of the internal combustion engine in an operation state with a short valve overlap period in order to lengthen the valve overlap period when the vibration level is not a predetermined level. That is, the abnormality detection of the variable valve timing device cannot always be executed, and the timing at which the abnormality detection of the variable valve timing device can be executed is limited. For this reason, if the internal combustion engine is operated without being in such an engine operating state, even if an abnormality occurs in the variable valve timing device, the abnormality cannot be detected quickly.

  Accordingly, an object of the present invention is to provide an intake system abnormality detection device capable of quickly detecting an abnormality in an intake system component.

In order to solve the above-described problem, the first invention includes a knock detection device that detects a value of a parameter related to knocking of an internal combustion engine, and an operation parameter detection device that detects a value of an operation parameter other than the parameter related to knocking. The initial value in the engine operation state that is the same as or similar to the current engine operation state estimated based on the value of the parameter related to knocking detected by the knock detection device and the value of the operation parameter detected by the operation parameter detection device Or when the difference with the parameter value regarding the past knocking is more than a predetermined value, it is judged that the intake system component of the internal combustion engine is abnormal.
According to the first invention, it is possible to determine abnormality of the intake system components regardless of the engine operating state. Therefore, it is possible to quickly detect abnormality in the intake system components.

  In a second invention, in the first invention, the knock detection device can detect knocking for each cylinder of an internal combustion engine having a plurality of cylinders, and a cylinder in which a difference in parameter values related to knocking is a predetermined value or more. If there is one, it is determined that there is an abnormality in the open / close valve mechanism of the intake valve or exhaust valve of the cylinder, and if the difference in the parameter values related to knocking is greater than or equal to a predetermined value for all cylinders, the intake air It is determined that there is an abnormality in the intake system components arranged on the upstream side of the intake air from the branching portion of each pipe to each cylinder.

  In the third invention, in the second invention, when it is determined that there is an abnormality in the opening / closing valve mechanism of the intake valve or the exhaust valve, the opening / closing of the intake valve or the exhaust valve is performed based on the difference in the parameter values relating to the knocking. When the valve characteristics are corrected and it is determined that there is an abnormality in the intake system components, the throttle opening is corrected based on the difference in the parameter values related to the knocking.

  In order to solve the above-described problem, in a fourth aspect of the invention, a knock detection device for detecting a value of a parameter related to knocking of the internal combustion engine, and a value of the parameter related to knocking detected by the knock detection device An ignition timing correction means for correcting the ignition timing; and a parameter detection means for detecting a value of an operation parameter other than the parameter relating to the knocking; a current ignition timing corrected by the ignition timing correction means; and an operation parameter detection An intake system of an internal combustion engine if the difference between the current engine operating state estimated based on the value of the operating parameter detected by the device and the past ignition timing in the same or similar engine operating state is a predetermined value or more Judge that the component is abnormal.

  ADVANTAGE OF THE INVENTION According to this invention, the intake system abnormality detection apparatus which can detect the abnormality of an intake system component rapidly can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a case where the intake system abnormality detection device of the first embodiment of the present invention is applied to an in-cylinder injection type spark ignition internal combustion engine. The present invention can also be applied to other spark ignition internal combustion engines and compression self-ignition internal combustion engines.

  As shown in FIG. 1, in the present embodiment, the engine body 1 includes a cylinder block 2, a piston 3 that reciprocates within the cylinder block 2, and a cylinder head 4 fixed on the cylinder block 2. . A combustion chamber 5 is formed between the piston 3 and the cylinder head 4. In the cylinder head 4, an intake valve 6, an intake port 7, an exhaust valve 8, and an exhaust port 9 are arranged for each cylinder. Further, as shown in FIG. 1, a spark plug 10 is disposed at the center of the inner wall surface of the cylinder head 4, and a fuel injection valve 11 is disposed around the inner wall surface of the cylinder head 4. Further, a cavity 12 extending from the lower side of the fuel injection valve 11 to the lower side of the spark plug 10 is formed on the top surface of the piston 3.

  The intake port 7 of each cylinder is connected to a surge tank 14 via an intake branch pipe 13, and the surge tank 14 is connected to an air cleaner 16 via an intake pipe 15. A throttle valve 18 driven by a step motor 17 is disposed in the intake pipe 15. On the other hand, the exhaust port 9 of each cylinder is connected to a catalytic converter 21 containing an exhaust purification device 20 via an exhaust branch pipe and an exhaust pipe 19, and this catalytic converter 21 communicates with the atmosphere via a muffler (not shown). Is done. The intake valve 6 and the exhaust valve 8 of each cylinder are driven to open and close by an intake valve drive device (variable valve mechanism) 22 and an exhaust valve drive device (variable valve mechanism) 23, respectively. The intake valve drive device 22 and the exhaust valve drive device 23 can change the operating angle and lift amount of the intake valve 6 and the exhaust valve 8, respectively.

  An electronic control unit (ECU) 31 comprises a digital computer, and is connected to each other via a bidirectional bus 32, a RAM (random access memory) 33, a ROM (read only memory) 34, a CPU (microprocessor) 35, an input A port 36 and an output port 37 are provided.

  An air flow meter 40 for detecting the flow rate of air (intake gas) passing through the intake pipe 15 is disposed in the intake pipe 15 on the intake upstream side of the throttle valve 18. The cylinder block 2 of the engine body 1 is provided with a knock sensor 41 for detecting the value of a parameter relating to knocking that has occurred in the combustion chamber of each cylinder, as will be described later. Further, a load sensor 43 that generates an output voltage proportional to the amount of depression of the accelerator pedal 42 is connected to the accelerator pedal 42, and a throttle opening degree sensor 44 that detects the opening degree of the throttle valve 18 is connected to the throttle valve 18. Provided. The output signals of these sensors 40, 41, 43, and 44 are input to the input port 36 through corresponding AD converters 38, respectively. Further, a crank angle sensor 45 that generates an output pulse every time the crankshaft rotates, for example, 30 ° is connected to the input port 36. The CPU 35 calculates the engine speed based on the output pulse of the crank angle sensor 44. On the other hand, the output port 37 is connected to the spark plug 10, the fuel injection valve 11, the step motor 17, the intake valve drive device 22, and the exhaust valve drive device 23 through corresponding drive circuits 39, which are connected to the output from the ECU 31. Based on control.

  In the present embodiment, the knock sensor 41 detects vibration acceleration due to knocking transmitted to the cylinder block 2, and based on the vibration acceleration detected by the knock sensor 41, for example, the presence or absence of knocking, occurrence of knocking The frequency and strength can be detected.

  Specifically, the knock sensor 41 detects vibration transmitted to the cylinder block 2 by a piezoelectric element and converts such vibration into an electric signal. Generally, when knocking occurs, high-frequency pressure vibration (5 to 9 kHz) is generated in the cylinder. This pressure vibration is also transmitted to the cylinder block 2, so that when knocking occurs, high-frequency vibration is also generated in the cylinder block 2. Therefore, when a vibration acceleration sensor (knock sensor) is attached to the cylinder block 2 and the sensor output is compared with the presence or absence of knocking, the difference clearly appears in a specific frequency band. Therefore, the knock sensor 41 detects the presence or absence of knocking by extracting the vibration component in the specific frequency band by passing through an electrical filter (bandpass filter).

  Further, the occurrence frequency of knocking can be estimated from the frequency at which high-frequency vibration is detected in the specific frequency band by the knock sensor 41, that is, the number of detection times or detection time of high-frequency vibration per unit cycle or unit time. Further, since the amplitude of the high-frequency vibration tends to increase as the strength or degree of knocking increases, the strength or degree of knocking can be estimated by detecting the amplitude of the high-frequency vibration.

  FIG. 2 is a diagram showing how the on-off valve characteristics of the intake valve 6 change as the intake valve drive device 22 operates. In the present embodiment, the phase angle and operating angle (lift amount) of the intake valve 6 are continuously changed with the operation of the intake valve drive device 22. Here, the “phase angle” means the valve opening timing or the valve closing timing of the intake valve 6, and the change in the phase angle means that the valve opening timing or the valve closing timing changes (for example, a solid line → broken line). . “Operating angle” means a crank angle from when the intake valve 6 is opened until the valve is closed, and a change in the operating angle means that the crank angle from the opening of the intake valve 6 to the closing is changed. Meaning (for example, solid line → dash-dot line). In particular, according to the intake valve drive device 22 of the present embodiment, the lift amount of the intake valve 6 is increased as the operating angle of the intake valve 6 is increased.

  Specifically, the intake valve drive device 22 has a relative angle change mechanism that changes the rotation angle of the intake camshaft with respect to the rotation angle of the crankshaft, and changes the phase angle of each intake valve 6 by this relative angle change mechanism. is doing. Further, the intake valve drive device 22 has a thickness changing mechanism that provides a predetermined member between the cam profile surface of each intake cam and the stem end portion of the intake valve and changes the thickness of the predetermined member. The operating angle of the intake valve 6 is changed by the thickness changing mechanism. In the present embodiment, similarly, the phase angle and the working angle (lift amount) of the exhaust valve 8 are continuously changed with the operation of the exhaust valve driving device 23.

  By the way, in the internal combustion engine as in the present embodiment, the opening degree of the throttle valve 18 (hereinafter referred to as “throttle opening degree”), the intake valve 6 and the exhaust gas according to the engine load, that is, the depression amount of the accelerator pedal 42 and the like. The values of parameters related to the operation of the internal combustion engine (hereinafter referred to as “operation parameters”) such as the on-off valve characteristics, fuel injection amount, and ignition timing of the valve 8 are changed.

  For example, when the engine load is low, the cylinder opening air amount is reduced by reducing the throttle opening, and the intake valve 6 and the exhaust valve 8 are simultaneously open (hereinafter referred to as “valve overlap period”). Is shortened to increase the ratio of exhaust gas in the intake gas flowing into the combustion chamber 5 of each cylinder (hereinafter referred to as “EGR rate”). Thereby, combustion of intake gas becomes small, the output of the internal combustion engine becomes low, and fuel consumption can be reduced. Conversely, when the engine load is high, the amount of air charged in the cylinder is increased and the EGR rate is decreased. Thereby, combustion of intake gas becomes large and the output of the internal combustion engine is increased.

  Fuel injection is performed from the fuel injection valve 11 into the combustion chamber 5 of each cylinder so that the air-fuel ratio of the air-fuel mixture in the combustion chamber 5 becomes the target air-fuel ratio based on the amount of cylinder charge air, the EGR rate, and the like. Is called. That is, the in-cylinder charged air amount, the EGR rate, and the like are estimated by the ECU 31 based on the throttle opening and the on-off valve characteristics of the intake valve 6 and the exhaust valve 8, and based on the estimated in-cylinder charged air amount and the target air-fuel ratio. The fuel injection amount is calculated, and fuel is injected from the fuel injection valve 11. The target air-fuel ratio is calculated by the ECU 31 based on the engine load and the like. For example, when the engine load is high, the target air-fuel ratio is almost equal to the stoichiometric air-fuel ratio so that homogeneous combustion is performed in the combustion chamber 5 in order to increase the engine output. When the engine load is low, the engine is lean so that stratified combustion is performed in the combustion chamber 5 to ensure fuel consumption.

  The ignition timing by the spark plug 10 is determined so that the engine output becomes maximum based on the in-cylinder charged air amount, the EGR rate, and the engine speed. That is, generally, an optimum ignition timing (MBT: Minimum advance for Best Torque) for obtaining a maximum torque is determined for each in-cylinder charged air amount, EGR rate, and engine speed, and therefore, the estimated in-cylinder charged air amount. Based on the above, the ECU 31 calculates the optimum ignition timing, and ignition by the spark plug 10 is performed at the optimum ignition timing.

  By the way, for example, when the intake valve 6 and the intake valve drive device 22 are broken or deteriorated over time, the intake valve 6 may be opened and closed with an on / off valve characteristic different from the on / off valve characteristic indicated by the ECU 31. On the other hand, the EGR rate is calculated based on the on-off valve characteristics instructed by the intake valve driving device 22 from the ECU 31. Therefore, if the intake valve 6 and the intake valve drive device 22 fail or deteriorate over time, the EGR rate estimated by the ECU 31 and the actual EGR rate differ from each other, and the fuel is based on the EGR rate estimated by the ECU 31 as it is. When the injection amount and the ignition timing are determined, the air-fuel ratio deviates from the target air-fuel ratio, and the ignition timing deviates from the optimal ignition timing, so that the internal combustion engine is not properly controlled.

  This is not limited to the failure and deterioration over time of the intake valve 6 and the intake valve drive device 22, but includes the throttle valve 18, the exhaust valve 8, the exhaust valve drive device 23, the air flow meter 40, and the like in the combustion chamber 5 of each cylinder. This may occur when a component related to control of the intake gas flowing into the engine (hereinafter referred to as “intake system component”) malfunctions or abnormalities such as deterioration over time. Therefore, in order to properly maintain the control of the internal combustion engine, an abnormality detection device for detecting such an abnormality is required.

  Accordingly, the present invention provides an abnormality detection device for detecting an abnormality that has occurred in an intake system component based on knocking that occurs in an internal combustion engine. Hereinafter, the abnormality detection device of the present invention will be described in detail.

  First, the principle of knocking and the relationship between the occurrence of knocking and abnormalities in the intake system components will be described. In the spark ignition type internal combustion engine as in the present embodiment, the air-fuel mixture in the combustion chamber 5 is usually ignited by the spark plug 10, and by this ignition, the air-fuel mixture in the vicinity of the spark plug 10 is ignited and burned therefrom. Combustion is performed by the flame gradually spreading toward the outer periphery of the chamber 5. However, if the air-fuel mixture in the combustion chamber 5 is at a high pressure and high temperature during ignition by the spark plug 10, the air-fuel mixture is self-ignited in a region in the combustion chamber 5 other than the ignition region by the spark plug 10. . When such self-ignition occurs, combustion is performed in a good combustion state around the surroundings. As a result, combustion of the air-fuel mixture is performed at once in the combustion chamber 5, and the combustion chamber 5 and the cylinder block 2 are combusted. It becomes a factor that generates vibration and the like.

  Therefore, generally, when the amount of air filled in the cylinder is large and when the EGR rate is high (that is, when a lot of high-temperature exhaust gas is filled), the air-fuel mixture becomes high pressure and high temperature, so that knocking is likely to occur. Conversely, knocking is unlikely to occur when the amount of air filled in the cylinder is small and when the EGR rate is low. For this reason, normally, when the amount of air charged in the cylinder is large and when the EGR rate is high, the optimal ignition timing is set to a relatively early timing, whereby the air-fuel mixture is ignited early and knocking occurs. It is suppressed. On the contrary, when the in-cylinder charged air amount is small and when the EGR rate is low, knocking is unlikely to occur, so the optimal ignition timing is set to a relatively late timing.

  However, when an abnormality occurs in the intake system components, the actual in-cylinder charged air amount and EGR rate are different from the estimated in-cylinder charged air amount and EGR rate as described above. As described above, there are cases in which knocking occurs, the frequency of occurrence of knocking increases, or the strength of knocking increases even though the ignition timing is controlled. Therefore, in this embodiment, when the occurrence frequency of knocking and the strength of knocking in a certain engine operating state are greatly different from the expected occurrence frequency of knocking and the strength of knocking from the engine operating state. It is determined that an abnormality has occurred in the intake system components.

  Next, an abnormality detection method using the abnormality detection apparatus of the present invention will be described. In this embodiment, the engine load is detected by the output of the load sensor 43, the throttle opening is detected by the output of the throttle opening sensor 44, and the engine speed is detected by the output of the crank angle sensor 45 during engine operation. In addition, values of operating parameters such as humidity, intake air temperature, and air-fuel ratio are detected during engine operation based on the output of a predetermined sensor. The engine operating state Ic is specified from the values of these operating parameters. On the other hand, the occurrence, occurrence frequency, or strength (hereinafter referred to as “knock strength”) Nc of knocking is detected during engine operation based on the output of the knock sensor 41 separately from these operation parameters.

  Further, the ECU 31 stores a relationship between the engine operating state Ic and the knock strength during normal operation as a map. That is, the relationship between the knock strength (hereinafter referred to as “reference knock strength”) Np and the engine operating state Ic when there is no abnormality in the intake system components such as the throttle valve 18, the intake valve 6 and the exhaust valve 8. It is calculated beforehand by experiment or calculation, and the relationship between the engine operating state Ic and the reference knock strength Np is stored as a map. Therefore, when there is no abnormality in the intake system components, the reference knock strength Np calculated by the map based on the engine operating state Ic specified based on the value of the operating parameter detected during engine operation, The knock strength Nc detected by the knock sensor 41 is almost the same value.

  However, when there is an abnormality in the intake system components, the in-cylinder charged air amount and the EGR rate are deviated as described above, and therefore, the engine operating state specified based on the operating parameters detected during engine operation. The reference knock strength Np calculated by the map based on Ic and the knock strength Nc detected by the knock sensor 41 are greatly different values.

  Therefore, in the present embodiment, at least one difference between the reference knock strength Np and the knock strength Nc detected by the knock sensor 41 (hereinafter simply referred to as “knock strength difference”) is the reference in the cylinder. If it is greater than the value (predetermined value) Nd, it is determined that there is an abnormality in the intake system components. Specifically, for example, when the occurrence frequency of knocking is used as the knock strength, the difference between the occurrence frequency of knocking calculated from the map and the occurrence frequency of knocking detected by the knock sensor 41 is based on the reference value Nd. In the case where the intake system component is abnormal and the knocking strength is used as the knocking strength, the knocking strength calculated from the map and the knocking strength detected by the knock sensor 41 Is greater than the reference value Nd, it is determined that there is an abnormality in the intake system components.

  In the present embodiment, the reference value Nd is basically the smallest value among the knock strength differences that cannot occur when there is no abnormality in the intake system components in all operating states. In other words, the reference value Nd is basically set to a value such that there is an abnormality in the intake system components when the difference in knock strength is greater than the reference value Nd in any operating state.

  However, the reference value Nd is an instruction value related to the estimated cylinder filling air amount and the EGR rate, that is, the throttle opening estimated by the throttle opening sensor 44 and the on-off valve characteristics of the intake valve 6 and the exhaust valve 8. It is good also as a different value according to the valve overlap period estimated by. For example, when the in-cylinder charged air amount is small or the EGR rate is low, the intake gas in the combustion chamber 5 is unlikely to become high temperature and high pressure, so that knocking hardly occurs. Therefore, if knocking occurs in such a case, it is considered highly likely that an abnormality has occurred in the intake system components. Therefore, as shown in FIG. 3, when the operating state is in the region X, that is, when the in-cylinder charged air amount is small and the EGR rate is low, the reference value Nd is set to a small value, and the operating state is in the region Y. In this case, that is, when the in-cylinder charged air amount is large and the EGR rate is high, the reference value Nd is set to a large value.

  By the way, as described above, the knock sensor 41 can detect the occurrence, occurrence frequency, or strength (knock strength Nc) of knocking for each cylinder by specifying the generation time of the high-frequency vibration. Here, for example, when the difference in knock strength is larger than the reference value Nd only in one cylinder and the difference in knock strength is small in the other cylinders, It is conceivable that an abnormality in the intake system component has occurred in only one cylinder. In the present embodiment, the intake system components provided on the intake downstream side of the branch portions of the intake pipes 13 and 15 to the cylinders are only the intake valve 6 and the exhaust valve 8, and therefore the intake system for only one cylinder. When abnormality of the component has occurred, it is considered that abnormality has occurred in the intake valve 6 and the exhaust valve 8 or their driving devices 22 and 23. Therefore, in the present embodiment, when the difference in knock strength for only one cylinder is larger than the reference value Nd, the constituent elements 6 and 8 relating to the intake / exhaust valves corresponding to the cylinder. It is determined that 22 and 23 are abnormal.

  On the other hand, for example, when the difference in the knocking strength is greater than the reference value Nd for all the cylinders, the intake pipes 13 and 15 are arranged on the intake upstream side of the branch portions to the respective cylinders. An abnormality in the intake system components may have occurred. Therefore, in the present embodiment, when the difference in knock strength is greater than the reference value Nd for a plurality of cylinders, the intake system configuration provided on the intake upstream side of the branch portion It is determined that there is an abnormality in the elements (for example, the throttle valve 18 and the air flow meter 40).

  FIG. 4 is a flowchart of a control routine of intake system abnormality detection control in the present embodiment. First, in step 101, the engine operating state Ic is acquired based on the detected values of various operating parameters, and the knock strength Nc is acquired based on the output of the knock sensor 41. Next, at step 102, the reference knock strength Np is calculated from the map based on the engine operating state Ic acquired at step 101. In step 103, it is determined whether or not the absolute value of the difference between the knock strength Nc detected by the knock sensor 41 and the reference knock strength Np obtained from the map is greater than the reference value Nd. When it is determined that the absolute value of the difference is equal to or less than the reference value Nd (| Nc−Np | ≦ Nd), the control routine is terminated assuming that no abnormality has occurred in the intake system components.

  On the other hand, when it is determined in step 103 that the absolute value of the difference is larger than the reference value Nd (| Nc−Np |> Nd), that is, when it is determined that an abnormality has occurred in the intake system components. Then, go to Step 104. In step 104, it is determined whether or not the knock strength Nc detected by the knock sensor 41 differs between the cylinders. When it is determined that the knock strength Nc is different between the cylinders, the routine proceeds to step 105, where it is displayed that there is an abnormality in the constituent elements 6, 8, 22, 23 related to the intake / exhaust valves. On the other hand, if it is determined in step 104 that the knock strength Nc is not different between the cylinders, the routine proceeds to step 106 where there is an abnormality in the intake system components provided upstream of the branching portion. Is displayed.

  In the above embodiment, the engine operating state Ic is a state specified based on operating parameters such as engine load, throttle opening, engine speed, humidity, intake air temperature, air-fuel ratio, and the like. It may be specified based on other operating parameters, and some operating parameters (for example, engine load and engine speed) are not specified based on all these operating parameters. Only) may be specified.

  Moreover, in the said embodiment, the relationship between the engine operating state Ic and the reference | standard knock strength Np is calculated | required previously by experiment or calculation, and is preserve | saved as a map in ROM34 of ECU31. However, the relationship between the engine operating state Ic and the reference knock strength Np may be sequentially updated during engine operation without being obtained in advance through experiments or calculations. That is, the knock strength detected by the knock sensor 41 in a certain engine operating state may be stored in the ROM 34 of the ECU 31 as the reference knock strength Np in the engine operating state. As a result, even if the relationship between the engine operating state Ic and the reference knock strength Np slightly changes with the operation of the internal combustion engine, the change can be compensated.

  However, when the relationship between the engine operating state Ic and the reference knock strength Np is sequentially updated during engine operation, it is necessary to stop the update when the difference in knock strength is greater than the reference value Np. is there. This is because if the update is performed at such time, the knock strength after the change due to abnormality in the intake system components may be set as the reference knock strength. In addition, the update of the reference knock strength Np in a certain engine operating state Ic is performed by an average value or a weighted average value of a plurality of knock strengths Nc detected by the knock sensor 41 in the engine operating state. preferable.

  In addition, when the relationship between the engine operating state Ic and the reference knock strength Np is sequentially updated during engine operation, it is difficult to determine the abnormality due to aged deterioration considering that the abnormality due to aged deterioration gradually proceeds. is there. Therefore, the sequential update as described above is particularly suitable for determining an abnormality caused by a failure of an intake system component.

  Further, the relationship between the engine operation state Ic and the reference knock strength Np may be acquired during the initial operation. That is, only during the initial operation, the knock strength detected by the knock sensor 41 in a certain engine operating state may be stored in the ROM 34 of the ECU 31 as the reference knock strength Np in the engine operating state. Here, the initial operation means a period from when the use of the internal combustion engine is started until a certain amount of operation is performed. Specifically, for example, the travel distance of the vehicle on which the internal combustion engine is mounted is It means until reaching a certain distance. Thereby, the relationship between the engine operating state Ic in the initial state and the reference knock strength Np can be obtained for each internal combustion engine. Further, since the relationship between the engine operation state Ic and the reference knock strength Np is updated only during the initial operation, the relationship between the engine operation state Ic and the reference knock strength Np is sequentially updated during the engine operation. In contrast, abnormalities in the intake system components due to deterioration over time can also be determined.

  Next, an intake system abnormality detection device according to a second embodiment of the present invention will be described. The intake system abnormality detection device of the second embodiment is basically the same as the intake system abnormality detection device of the first embodiment, but in the second embodiment, when there is an abnormality in the intake system components, the abnormality In order to eliminate the error in the in-cylinder charged air amount or EGR rate caused by the above, the throttle opening or the open / close valve characteristics of the intake / exhaust valves are corrected.

  FIG. 5 is a flowchart of a control routine of intake system abnormality detection control in the present embodiment. Steps 121 to 125 and 127 are the same as steps 101 to 106 in FIG.

  When it is determined in steps 123 and 124 that the components 6, 8, 22, and 23 relating to the intake / exhaust valves are abnormal, the display is performed in step 125 as in the above embodiment, and the intake valve 6 Alternatively, the on / off valve characteristics of the exhaust valve 8 are corrected. For example, when the knock strength Nc detected by the knock sensor 41 is larger than the reference knock strength Np, the EGR rate is considered to be higher than the target EGR rate, so that the valve overlap period is shortened. The on-off valve characteristics of the intake valve 6 or the exhaust valve 8 are corrected. Conversely, when the knock strength Nc detected by the knock sensor 41 is smaller than the reference knock strength, it is considered that the EGR rate is lower than the target EGR rate, and therefore the intake air is increased so that the valve overlap period becomes longer. The on-off valve characteristics of the valve 6 or the exhaust valve 8 are corrected.

  On the other hand, when it is determined in steps 123 and 124 that there is an abnormality in the intake system components provided on the intake upstream side of the branch portion, the display is performed in step 127 as in the above embodiment. Then, parameters relating to the intake system components provided on the intake upstream side of the branch portion, in particular, the throttle opening of the throttle valve 18 are corrected. For example, when the knock strength Nc detected by the knock sensor 41 is larger than the reference knock strength Np, it is considered that the cylinder air charge amount is large, so the throttle opening is reduced. On the contrary, when the knock strength Nc detected by the knock sensor 41 is smaller than the reference knock strength Np, it is considered that the in-cylinder charged air amount is small, so the throttle opening is increased.

  Next, an intake system abnormality detection device according to a third embodiment of the present invention will be described. In the above embodiment, the ignition timing by the spark plug 10 is basically the optimum ignition timing calculated in the ECU 31 based on the estimated cylinder charge air amount, the estimated EGR rate, the engine speed, and the like. In this embodiment, the ignition timing is set by control (hereinafter referred to as “KCS control”) by KCS (knock control system). First, KCS control will be briefly described.

  In general, when the values of the other operation parameters are the same, the output torque tends to become the largest when the ignition timing is set to the most advanced side within the range where knocking does not occur. Therefore, in the KCS control, the ignition timing is controlled so as to be the most advanced within the range where knocking does not occur.

  Specifically, when the occurrence of knocking is detected by the knock sensor 41 during engine operation, or when the occurrence of knocking with a strength higher than a predetermined strength is detected, the ignition timing is retarded. Thereby, the occurrence of knocking can be suppressed / prevented, but in many cases, the output torque is simultaneously reduced. For this reason, when the occurrence of knocking is not detected by the knock sensor 41 during engine operation, or when the occurrence of knocking weaker than the predetermined strength is detected, the ignition timing is advanced. This increases the output torque, but also increases the possibility of knocking. By repeating such advance and retard of the ignition timing, the ignition timing is always maintained in the vicinity of the most advanced timing within a range where knocking does not occur.

FIG. 6 is a flowchart showing a control routine of calculation control of the KCS learning value in KCS control. First, in step 141, it is determined whether knocking has occurred based on the output of the knock sensor 41. If it is determined in step 141 that knocking has occurred, the process proceeds to step 142. In step 142, the KCS learning value Kc is set to a value obtained by adding a predetermined value ΔK ₁ to the value of the KCS learning value Kc one cycle or several cycles before (Kc = Kc + ΔK ₁ ). On the other hand, if it is determined in step 141 that knocking has not occurred, the process proceeds to step 143. In step 143, the KCS learning value Kc is set to a value obtained by subtracting the predetermined value ΔK ₂ from the value of the KCS learning value Kc one cycle or several cycles before (Kc = Kc−ΔK ₂ ). The actual ignition timing is a timing obtained by adding the KCS learning value Kc thus calculated to the reference ignition timing.

  Here, when KCS control is performed, if an abnormality occurs in the intake system components and the in-cylinder charged air amount or the EGR rate goes wrong, the ignition timing is considerably advanced or delayed as compared with the case where no abnormality occurs. It will be horned. For example, if an abnormality occurs in the throttle valve and the actual in-cylinder charged air amount becomes smaller than the estimated in-cylinder charged air amount, knocking is less likely to occur. Therefore, the ignition timing is considerably higher than when no abnormality has occurred. It will be delayed. Therefore, in this embodiment, when the difference between the current KCS learning value Kc and the past KCS learning value Kp is larger than the reference value Kd, it is determined that an abnormality has occurred in the intake system components.

As can be seen from the flowchart shown in FIG. 6, the difference between the KCS learning value one cycle before and the current KCS learning value Kc is basically ΔK ₁ or ΔK ₂ . Therefore, if the past KCS learning value Kp is set as the KCS learning value one cycle before, it is not possible to accurately detect a change in the KCS learning value due to an abnormality occurring in the intake system components. Therefore, in the present embodiment, as the past KCS learning value Kp, for example, the KCS learning value before several cycles, or the average value or weighted average value of the KCS learning values until several cycles before is used. In addition, the reference value Kd is basically the smallest value among the differences in the KCS learning value that cannot occur when there is no abnormality in the intake system components in all operating states. In other words, the reference value Kd is basically a value that is considered to be abnormal in the intake system components when the difference in the KCS learning value becomes larger than the reference value Kd in any operating state.

  FIG. 7 is a flowchart of a control routine of intake system abnormality detection control in the present embodiment. First, in step 161, the engine operating state Ic is acquired based on the detected values of various operating parameters, and the current KCS learning value Kc is acquired from the ECU 31 that is performing KCS control. Next, in step 162, the past KCS learning value Kp in the engine operating state Ic acquired in step 161 is acquired from the ROM 34 of the ECU 31.

  In step 163, it is determined whether or not the absolute value of the difference between the current KCS learning value Kc and the past KCS learning value Kp is larger than the reference value Kd. If it is determined that the absolute value of the difference is equal to or less than the reference value Kd (| Kc−Kp | ≦ Kd), the control routine is terminated assuming that no abnormality has occurred in the intake system components. On the other hand, if it is determined in step 163 that the absolute value of the difference is larger than the reference value Kd (| Kc−Kp |> Kd), the process proceeds to step 164 and an indication that there is an abnormality in the intake system components. Is done.

  In the above flowchart, steps 104 to 106 in FIG. 4 are executed instead of step 164 to determine whether there is an abnormality in the intake / exhaust valves or abnormalities in the intake system components upstream of the branching portion. It may be possible to make a judgment. In this case, in step 161, it is necessary to detect the knock strength Nc in addition to the engine operating state Ic and the current KCS learning value Kc.

  In the above description, the engine operating state Ic is determined based on operating parameters such as engine load, throttle opening, engine speed, humidity, intake air temperature, air-fuel ratio, and the like. A learning value may be included.

It is a figure which shows the whole internal combustion engine at the time of applying this invention to a cylinder injection type spark ignition internal combustion engine. It is the figure which showed a mode that the on-off valve characteristic of an intake valve changed with the action | operation of an intake valve drive device. It is a figure which shows the relationship between a cylinder filling air amount, an EGR rate, and a reference value. It is a figure which shows the flowchart of the control routine of intake system abnormality detection control. It is a flowchart of the control routine of the intake system abnormality detection control in the second embodiment. It is a flowchart which shows the control routine of calculation control of the KCS learning value in KCS control. It is a flowchart of the control routine of the intake system abnormality detection control in the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 6 Intake valve 8 Exhaust valve 10 Spark plug 11 Fuel injection valve 14 Surge tank 18 Throttle valve 22 Intake valve drive device 23 Exhaust valve drive device 31 ECU
41 knock sensor

Claims (4)

A knock detection device that detects a value of a parameter related to knocking of the internal combustion engine, and an operation parameter detection device that detects a value of an operation parameter other than the parameter related to knocking,
Initial or past in the engine operating state that is the same as or similar to the current engine operating state estimated based on the value of the parameter relating to knocking detected by the knock detecting device and the value of the operating parameter detected by the operating parameter detecting device An intake system abnormality detection device that determines that there is an abnormality in an intake system component of the internal combustion engine when a difference from a parameter value related to knocking is equal to or greater than a predetermined value.   The knock detection device can detect knocking for each cylinder of an internal combustion engine having a plurality of cylinders, and when there is one cylinder whose difference in parameter values related to knocking is equal to or greater than a predetermined value, intake of the cylinder When it is determined that there is an abnormality in the on-off valve mechanism of the valve or the exhaust valve, and the difference in the parameter values related to knocking is greater than or equal to a predetermined value for all cylinders, the intake air upstream from the branch portion of each intake pipe to each cylinder The intake system abnormality detection device according to claim 1, wherein it is determined that an intake system component disposed on the side is abnormal.   When it is determined that there is an abnormality in the on-off valve mechanism of the intake valve or exhaust valve, the on-off valve characteristics of the intake valve or exhaust valve are corrected based on the difference in the parameter values related to knocking, and the intake system components The intake system abnormality detection device according to claim 2, wherein when it is determined that there is an abnormality, the throttle opening is corrected based on a difference in parameter values relating to the knocking. A knock detecting device for detecting a value of a parameter relating to knocking of the internal combustion engine, an ignition timing correcting means for correcting an ignition timing of the internal combustion engine based on a value of the parameter relating to knocking detected by the knock detecting device, and the above-mentioned knocking Parameter detecting means for detecting values of operating parameters other than parameters,
Past ignition in the engine operating state that is the same as or similar to the current engine operating state estimated based on the current ignition timing corrected by the ignition timing correcting means and the value of the operating parameter detected by the operating parameter detecting device An intake system abnormality detection device that determines that there is an abnormality in an intake system component of an internal combustion engine when a difference from a timing is a predetermined value or more.

Images