JP2011027087A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of more properly performing the fail-safe control by considering combustion characteristics per cylinder. <P>SOLUTION: This control device for the internal combustion engine includes a learning means and an abnormality occuring cylinder control-amount decision means. The learning means learns the control amount per each cylinder (10) based on output from a plurality of in-cylinder information output sections (21). The abnormality occuring cylinder control-amount decision means decides the control amount of the cylinder (10), in which abnormality has occurred, based on a result of the learning of the learning means in the case wherein abnormality occurs in any one of the plurality of in-cylinder information output sections (21). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  As this type of device, a control amount (ignition timing, fuel injection) for each cylinder of a multi-cylinder internal combustion engine in which in-cylinder information detection means (specifically, an in-cylinder pressure sensor) for detecting in-cylinder information is provided for each cylinder. (For example, JP 2006-144642 A, JP 2007-40207 A, etc.) that control the amount, fuel injection timing, etc.) based on the detection value of the in-cylinder information detection means. (See JP 2007-255237 A, JP 2008-231995 A, JP 2008-297922 A, etc.).

  In this type of apparatus, when an abnormality such as a failure or deterioration occurs in the in-cylinder information detecting means in any cylinder, the in-cylinder information corresponding to the cylinder (abnormality-occurring cylinder) cannot be obtained. Therefore, in this case, there is a possibility that good control for the abnormal cylinder cannot be performed.

  Therefore, the device disclosed in Japanese Patent Application Laid-Open No. 2007-40207 performs fail-safe control using the detection value of the in-cylinder information detecting means in the cylinders other than the abnormality occurrence cylinder (the control amount of the abnormality occurrence cylinder is set to be controlled). Control).

  Specifically, this apparatus learns a deviation between the detection values of the in-cylinder information detecting means corresponding to each cylinder before the occurrence of abnormality, and the learning result and cylinders other than the abnormality occurrence cylinder (preferably Is used to control the control amount of the cylinder in which the abnormality has occurred, using the detected value of the in-cylinder information detection means in the ignition sequence immediately before the cylinder in which the abnormality has occurred.

  In the conventional apparatus disclosed in Japanese Patent Laid-Open No. 2007-40207, as described above, the deviation between the detected values of the in-cylinder information detecting means corresponding to each cylinder, that is, the above-described corresponding to each cylinder. Each characteristic of the in-cylinder information detecting means is taken into consideration. However, it cannot be said that the respective characteristics of the in-cylinder information detecting means corresponding to each cylinder correspond to the combustion characteristics of each cylinder.

  The present invention has been made to address such problems. That is, an object of the present invention is to perform more appropriate fail-safe control by considering the combustion characteristics of each cylinder.

  An internal combustion engine control apparatus that is an object of the present invention is a combustion state in each cylinder of a multi-cylinder internal combustion engine in which an in-cylinder information output unit that generates an output corresponding to the in-cylinder state (in-cylinder pressure or the like) is provided for each cylinder. Is controlled based on the output of the in-cylinder information output unit. This control amount includes, for example, an ignition timing that is feedback-controlled based on the output from the in-cylinder information output unit.

  That is, the internal combustion engine control device according to the present invention is based on the output of the first in-cylinder information output unit provided corresponding to the first cylinder when all the in-cylinder information output units are normal. The control amount in the first cylinder is controlled, and the control amount in the second cylinder is controlled based on the output of the second in-cylinder information output unit provided corresponding to the second cylinder different from the first cylinder. It is supposed to be.

  A feature of the present invention is that, when an abnormality occurs in any one of the plurality of in-cylinder information output units, the abnormality occurrence cylinder in the cylinder in which an abnormality has occurred is a cylinder corresponding to the in-cylinder information output unit. In order to appropriately control (determine) the control amount, the following configuration is provided.

  That is, the internal combustion engine control device of the present invention includes learning means and abnormality occurrence cylinder control amount determination means. The learning means learns the control amount in each cylinder (for example, learns an inter-cylinder deviation of the control amount) based on outputs from the plurality of in-cylinder information output units (before occurrence of abnormality). It has become. The abnormality occurrence cylinder control amount determining means determines the control amount in the abnormality occurrence cylinder based on a learning result by the learning means.

  The abnormality occurrence cylinder control amount determining means determines the control amount in the abnormality occurrence cylinder based on a relative relationship of the control amount between the abnormality occurrence cylinder and a normal cylinder different from the abnormality occurrence cylinder. It may be. In this case, specifically, for example, the abnormality occurrence cylinder control amount determination means includes the abnormality occurrence cylinder and a reference cylinder having the control amount closest to the abnormality occurrence cylinder among the normal cylinders. The control amount in the abnormality occurrence cylinder is determined based on the relative relationship between the control amounts.

  In the internal combustion engine control apparatus of the present invention having such a configuration, the control amount in each cylinder is learned based on outputs from the plurality of in-cylinder information output units (before occurrence of abnormality). This learning result reflects the combustion characteristics in each cylinder. Then, when an abnormality occurs in any one of the plurality of in-cylinder information output units, the control amount in the abnormality occurrence cylinder is determined based on the learning result.

  Thus, in the present invention, the control amount in the abnormality occurrence cylinder is determined based on the learning result of the combustion characteristic in each cylinder, which is different from the characteristic of the in-cylinder information detection means corresponding to each cylinder. It is determined. Therefore, according to the present invention, more appropriate fail-safe control is performed in consideration of the combustion characteristics of each cylinder.

1 is a diagram showing a schematic configuration of a system (vehicle) including a piston reciprocating spark ignition type in-line multi-cylinder (four cylinders) four-cycle internal combustion engine and an internal combustion engine control apparatus according to an embodiment of the present invention. 2 is a time chart showing a specific example of the operation of the internal combustion engine control device of the present embodiment shown in FIG. 1. 2 is a flowchart showing a specific example of the operation of the internal combustion engine control device of the present embodiment shown in FIG. 1. It is a conceptual diagram which shows the specific example at the time of applying this invention to cylinder intake air amount detection. It is a conceptual diagram which shows the specific example at the time of applying this invention to fuel injection amount detection. It is a conceptual diagram which shows the specific example at the time of applying this invention to EGR rate control.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in.

  Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Various modifications that can be made to the present embodiment are listed together at the end, as they would interfere with the understanding of the consistent description of the embodiment if inserted during the description of the embodiment. .

<Configuration>
FIG. 1 shows a piston reciprocating spark ignition type in-line multi-cylinder (four-cylinder) four-cycle internal combustion engine 1 (hereinafter simply referred to as “internal combustion engine 1”), and internal combustion engine control according to an embodiment of the present invention. It is a figure which shows schematic structure of the system S (vehicle) containing the apparatus 2. FIG. Hereinafter, the configuration of the system S will be described with reference to FIG.

<< Internal combustion engine >>
In the internal combustion engine 1, a plurality (four) of cylinders 10 are arranged in series. A piston 11 is accommodated in the cylinder 10 so as to be capable of reciprocating in the vertical direction in the figure. The piston 11 is connected to a crankshaft 12 provided below via a connecting rod 13. A combustion chamber CC is formed by a portion above the top surface of the piston 11 in the space in the cylinder 10.

  The internal combustion engine 1 is provided with an in-cylinder injector 14 for each cylinder 10. That is, the same number of in-cylinder injectors 14 as the number of cylinders 10 is provided in the internal combustion engine 1. The in-cylinder injector 14 is configured and arranged so as to inject fuel directly into the combustion chamber CC.

  The internal combustion engine 1 is provided with a spark plug 15 for each cylinder 10. That is, as many spark plugs 15 as the number of cylinders 10 are provided in the internal combustion engine 1. The spark plug 15 is arranged so that the spark generating electrode at the tip thereof is exposed in the combustion chamber CC, and is configured to ignite the fuel mixture in the combustion chamber CC by generating a spark when energized. ing.

  The intake port of each cylinder 10 is opened and closed by an intake valve 16. These intake ports are connected to an intake passage 17 via an intake manifold. A surge tank 17 a is formed in the intake passage 17. A throttle valve 17b is interposed upstream of the surge tank 17a in the intake air flow direction.

  The exhaust port of each cylinder 10 is opened and closed by an exhaust valve 18. These exhaust ports are connected to the exhaust passage 19 via an exhaust manifold.

  In the middle of the exhaust passage 19, an upstream catalytic converter 19a and a downstream catalytic converter 19b for removing harmful components in the exhaust gas are interposed. The upstream catalytic converter 19a and the downstream catalytic converter 19b include a so-called three-way catalyst having an oxygen storage function, and are configured to purify HC, CO, and NOx in the exhaust gas.

<< Internal combustion engine controller >>
The internal combustion engine control device 2 includes an electronic control unit 20 (hereinafter referred to as “ECU 20”) that constitutes the learning means and the abnormality occurrence cylinder control amount determination means of the present invention.

  The ECU 20 is a so-called microcomputer including a CPU, a ROM, a RAM, a backup RAM, and an interface. The ECU 20 includes an in-cylinder injector 14, a spark plug 15, a throttle valve 17b and other operating units, an in-cylinder pressure sensor 21, and a crank position. The sensor 22, knock sensor 23, air flow meter 24, and other sensors are electrically connected. In other words, the internal combustion engine control device 2 is configured to receive signals from these sensors and to send an operation signal to the above-described operation unit based on the calculation result of the CPU corresponding to the signals.

  The in-cylinder pressure sensor 21 is provided for each cylinder 10. That is, the same number of cylinder pressure sensors 21 as the number of cylinders 10 are provided in the internal combustion engine 1. The in-cylinder pressure sensor 21 as the in-cylinder information output unit of the present invention is configured to output a signal corresponding to the pressure in the combustion chamber CC (in-cylinder pressure Pc).

The crank position sensor 22 is configured to output a waveform signal having a pulse corresponding to the rotation angle (CA) of the crankshaft 12. The knock sensor 23 is configured to output a signal corresponding to the magnitude of vibration (KNK) of the internal combustion engine 1. The air flow meter 24 is attached to the intake passage 17 and outputs a signal corresponding to the intake air flow rate Ga (load factor KL _AFM ) that is a mass flow rate per unit time of the intake air flowing through the intake passage 17. It is configured.

<Specific Example of Operation According to Configuration of Embodiment>
Next, an outline of ignition timing control, which is a specific example of the operation of the internal combustion engine control device 2 of the present embodiment, will be described. The internal combustion engine control device 2 is configured to optimize the ignition timing of the fuel mixture in the combustion chamber CC of the internal combustion engine 1 so that a large torque can be obtained and knocking does not occur (MBT: MBT stands for Minimum advance for Best Torque). To control.

  That is, the internal combustion engine control device 2 calculates the combustion ratio of the fuel mixture in the combustion chamber CC (MFB: MFB is an abbreviation of Mass Fraction Burned) based on the output of the in-cylinder pressure sensor 21, and ignites based on this combustion ratio. Feedback control of timing. Specifically, the internal combustion engine control device 2 performs feedback control of the ignition timing so that the combustion ratio MFB at ATDC 8 ° [CA] becomes the target value 50%.

  Therefore, when all the in-cylinder pressure sensors 21 are normal, the description will be made in accordance with the ignition sequence. Based on the output of the in-cylinder pressure sensor 21 provided corresponding to the # 1 cylinder, the ignition timing of the # 1 cylinder is MBT. Based on the output of the in-cylinder pressure sensor 21 provided corresponding to the # 3 cylinder, the ignition timing of the # 3 cylinder is controlled to MBT, and the in-cylinder pressure sensor 21 provided corresponding to the # 2 cylinder is controlled. The ignition timing of the # 2 cylinder is controlled to MBT based on the output, and the ignition timing of the # 4 cylinder is controlled to MBT based on the output of the in-cylinder pressure sensor 21 provided corresponding to the # 4 cylinder.

  Note that the calculation of the combustion ratio MFB based on the output of the in-cylinder pressure sensor 21 and the feedback control of the ignition timing based on the calculated combustion ratio MFB are not themselves an essential part of the present invention, but are also known. (For example, refer to JP-A-2006-144642, JP-A-2007-40207, etc.), and detailed description thereof is omitted in this specification.

  Here, if it is assumed that an abnormality has occurred in a certain cylinder pressure sensor 21 (for example, one corresponding to the # 2 cylinder), the combustion ratio MFB in the abnormality occurring cylinder cannot be monitored. Therefore, the internal combustion engine control device 2 according to the present embodiment uses the ignition timing of the abnormality occurrence cylinder (# 2 cylinder in this example) as the MBT of another normal cylinder (cylinder 10 in which no abnormality occurs in the in-cylinder pressure sensor 21). Good control (determination) is achieved by using the ignition timing.

  Specifically, the internal combustion engine control device 2 of the present embodiment first learns the MBT ignition timing (specifically, the cylinder deviation) in each cylinder 10 before the abnormality of the in-cylinder pressure sensor 21 occurs. The learning conditions at this time are as follows: (1) all in-cylinder pressure sensors 21 are normal, (2) steady operation continues for a predetermined time, and (3) MBT ignition timing feedback control based on the output of the in-cylinder pressure sensor 21 is performed. It is.

  FIG. 2A is a time chart showing a specific example of the operation of the internal combustion engine control device 2 of the present embodiment shown in FIG. As shown in FIG. 2A, the internal combustion engine control apparatus 2 is in a steady operation state of the system S and the internal combustion engine 1 (the amount of change ΔTA <α of the throttle valve opening TA: the vehicle speed is substantially constant at this time). Is calculated for each cylinder 10 and stored as an average value of ignition timing (SAlearn: BDTC ° [CA] in the figure) during that time.

  Here, the MBT ignition timing is determined by the combustion speed of each cylinder 10. Since this combustion speed changes depending on the mixed state of the fuel mixture in the combustion chamber CC, a slight deviation occurs between the plurality of cylinders 10. Therefore, the internal combustion engine control device 2 learns (calculates and stores) a deviation between the MBT ignition timings of each cylinder 10. The learning value of the cylinder-to-cylinder deviation of the MBT ignition timing is updated every time learning is performed.

  Thereafter, it is assumed that the internal combustion engine control device 2 determines that an abnormality has occurred in one certain in-cylinder pressure sensor 21 (for example, one corresponding to the # 2 cylinder). Such determination is well known as disclosed in Japanese Patent Application Laid-Open No. 2000-265887 and Japanese Patent Application Laid-Open No. 2001-20805, and detailed description thereof is omitted in this specification.

  The learning result of the cylinder-to-cylinder deviation of the MBT ignition timing is under a specific operating condition. However, it is considered that the inter-cylinder deviation of the MBT ignition timing does not change so greatly depending on the operating conditions. For this reason, by applying the inter-cylinder deviation of the MBT ignition timing learned under a specific operation condition to the MBT ignition timing of the normal cylinder under the other operation condition, the abnormality occurrence cylinder under the other operation condition (this Even if the ignition timing of the # 2 cylinder in the example is determined, the error from the MBT ignition timing that should be originally set (when the in-cylinder pressure sensor 21 corresponding to the # 2 cylinder is normal) is small. it is conceivable that.

  Therefore, the internal combustion engine control device 2 selects the cylinder 10 (for example, # 1 cylinder) having the smallest deviation from the abnormality occurrence cylinder (# 2 cylinder in this example) as the reference cylinder, and sets the latest MBT ignition timing in this reference cylinder. Based on the learned value of the deviation of the MBT ignition timing between the abnormality occurrence cylinder and the reference cylinder, the ignition timing in the current abnormality occurrence cylinder is determined.

  As described above, the MBT ignition timing deviation is determined by the combustion speed of each cylinder 10 and is not directly related to the ignition sequence. Therefore, as in the above-described example, the reference cylinder is not necessarily ignited immediately before or after the abnormal cylinder. In this regard, in the present embodiment, the reference cylinder is selected based on the learned value of the inter-cylinder deviation of the actual MBT ignition timing.

  Further, in the present embodiment, the cylinder of the MBT ignition timing, which is the result of feedback control based on the combustion ratio MFB calculated using the output of the in-cylinder pressure sensor 21, not the in-cylinder deviation of the output of the in-cylinder pressure sensor 21. The ignition timing in the malfunctioning cylinder is determined (MBT ignition timing is estimated) using the learning result of the interval deviation. In other words, in the present embodiment, fail-safe control is performed for the cylinder in which an abnormality has occurred based on the learning result of the combustion characteristics in each cylinder 10 that is different from the output characteristics of the in-cylinder pressure sensor 21 corresponding to each cylinder 10. Is called.

  Note that, even when an abnormality occurs in another in-cylinder pressure sensor 21 (for example, one corresponding to the # 3 cylinder), fail-safe control is performed as described above. In this case, among the normal cylinders (# 1 and # 4), the cylinder with the smallest deviation (for example, # 4 cylinder) from the abnormality occurrence cylinder (# 3 in this example) is selected as the reference cylinder. Further, there may be a case where the reference cylinders in the plurality of abnormality occurrence cylinders (for example, # 1 and # 3 cylinders) are the same (for example, # 2 cylinder).

  The flowchart of FIG. 2B summarizes the operation of the above specific example. That is, FIG. 2B is a flowchart showing a specific example of the operation of the internal combustion engine control device of the present embodiment shown in FIG. In FIG. 2B, “step” is abbreviated as “S”.

  The CPU provided in the ECU 20 starts the routine shown in FIG. 2B at a predetermined timing. When this routine is started, first, at step 210, it is determined whether or not there is an abnormality in the in-cylinder pressure sensor 21.

  Before sensor abnormality occurs (step 210 = No), the process proceeds to step 220, and normal ignition timing MBT feedback control based on the output of the in-cylinder pressure sensor 21 is performed. Thereafter, it is determined whether or not the above learning condition is satisfied (step 230). When the learning condition is satisfied (step 230 = Yes), learning is performed as described above (step 240), the learning result is updated (step 250), and this routine is temporarily ended.

  If a sensor abnormality occurs (step 210 = Yes), the process proceeds from step 260 onward. In step 260, an abnormal cylinder is identified. Next, at step 270, a reference cylinder for determining the ignition timing in the abnormality occurrence cylinder is selected. Subsequently, at step 280, the ignition timing in the abnormality occurrence cylinder is determined as described above. Thereafter, the process proceeds to step 290, the ignition timing of each cylinder is controlled, and this routine is temporarily ended.

  As described above, according to the present embodiment, even when an abnormality occurs in one of the plurality of in-cylinder pressure sensors 21, the ignition timing of the abnormality-occurring cylinder is set as good as the MBT ignition timing. The Therefore, according to the present embodiment, more appropriate fail-safe control is performed in consideration of the combustion characteristics for each cylinder 10.

<List of examples of modification>
Note that, as described above, the above-described embodiments are merely examples of typical embodiments of the present invention that the applicant has considered to be the best at the time of filing of the present application. Therefore, the present invention is not limited to the above-described embodiment.

  Therefore, it goes without saying that various modifications can be made to the above-described embodiment within the scope not changing the essential part of the present invention.

  Hereinafter, some typical modifications will be exemplified. Needless to say, the modifications are not limited to those listed below. In addition, a plurality of modified examples can be applied in a composite manner as appropriate within a technically consistent range.

  The present invention (especially those expressed functionally and functionally in the constituent elements constituting the means for solving the problems of the present invention) is based on the above-described embodiment and the description of the following modifications. Should not be interpreted as limited. Such a limited interpretation is unacceptable and improper for imitators, while improperly harming the applicant's interests (rushing to file under a prior application principle).

  (A) The present invention is not limited to the specific apparatus configuration disclosed in the above embodiment. For example, the present invention is applicable to gasoline engines, diesel engines, methanol engines, bioethanol engines, and any other type of internal combustion engine. The number of cylinders and the cylinder arrangement method (in-line, V-type, horizontally opposed) are not particularly limited.

  The internal combustion engine 1 may be provided with a port injector for injecting fuel into the intake port together with or in place of the in-cylinder injector 14. The present invention is preferably applied to such a configuration. Further, the number of spark plugs 15 that is an integral multiple (for example, twice) the number of cylinders 10 may be provided in the internal combustion engine 1. That is, a plurality of (for example, two) spark plugs 15 can be provided for each cylinder 10.

  (B) The present invention is not limited to the specific operations disclosed in the above embodiments.

  For example, the learning can be continuously performed in the normal cylinder while at least one in-cylinder pressure sensor 21 is normal. Further, fail-safe control can be performed while at least one in-cylinder pressure sensor 21 is normal (there is at least one normal cylinder).

  The learned value of the inter-cylinder deviation of the MBT ignition timing may be stored in a map together with other parameters (intake amount, engine speed, etc.). In this case, the learning value under the same condition (intake amount, engine speed, etc.) is updated every time learning is performed. Then, the internal combustion engine control device 2 selects the specific cylinder 10 having the smallest deviation from the abnormality occurrence cylinder in the current operating condition as the reference cylinder, the most recent MBT ignition timing in this reference cylinder, the abnormality occurrence cylinder and the reference cylinder. Based on the deviation of the MBT ignition timing with respect to the ignition timing, the ignition timing in the current abnormality occurrence cylinder is determined.

  (C) The present invention can be applied to other than ignition timing control. Specifically, for example, the present invention uses an in-cylinder pressure sensor 21 to detect in-cylinder intake air amount, fuel injection amount detection, EGR rate control (EGR is an abbreviation for Exhaust Gas Recirculation), etc. It is also applicable to.

  FIG. 3 is a conceptual diagram showing a specific example when the present invention is applied to in-cylinder intake air amount detection.

  A technique for detecting the in-cylinder intake air amount for each cylinder 10 based on the output of the in-cylinder pressure sensor 21 has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2008-297922). The detected in-cylinder intake air amount is used for air-fuel ratio control (fuel injection amount control).

  Here, it is assumed that an abnormality occurs in the in-cylinder pressure sensor 21 in the specific cylinder 10 (# 2 cylinder). In this case, as shown in FIG. 3, the in-cylinder intake air amount in the abnormal cylinder is unknown. Therefore, before an abnormality occurs in the in-cylinder pressure sensor 21, the in-cylinder intake air amount in each cylinder 10 is learned in advance, and the in-cylinder intake air amount in the abnormality occurrence cylinder is estimated based on the learning result. Even if any one of the in-cylinder pressure sensors 21 is abnormal, it is possible to perform good air-fuel ratio control.

  Specifically, the internal combustion engine control device 2 learns the air intake characteristics (relative ratio of the cylinder intake air amount) for each cylinder 10 when all the cylinder pressure sensors 21 are normal. This learning is performed for each region of operating conditions (engine speed, air filling rate, etc.) based on the internal energy (PV) during the compression stroke, which is used for estimating the in-cylinder intake air amount. When the system S shown in FIG. 1 is provided with an EGR system, the EGR rate is also included in the above operating conditions (that is, the learning region includes the engine speed, the air filling rate, and the EGR rate). It becomes a three-dimensional map.)

  When an abnormality occurs in the in-cylinder pressure sensor 21 in the specific cylinder 10 (# 2 cylinder), the output of the in-cylinder pressure sensor 21 of the specific normal cylinder (for example, # 1 cylinder) closest to the air intake characteristic is the same. On the basis of the calculated in-cylinder intake air amount (internal energy during the compression stroke) and the learning result in the current operating condition, the in-cylinder intake air amount in the cylinder in which the abnormality has occurred can be estimated.

  FIG. 4 is a conceptual diagram showing a specific example when the present invention is applied to fuel injection amount detection.

  As is well known, the amount of heat generation can be calculated from the output of the in-cylinder pressure sensor 21. Therefore, it is possible to detect the fuel injection amount in each cylinder 10 by calculating the amount of heat generated by the combustion in each cylinder 10. The detected fuel injection amount is used for air-fuel ratio control (fuel injection amount control).

  Here, it is assumed that an abnormality occurs in the in-cylinder pressure sensor 21 in the specific cylinder 10 (# 2 cylinder). In this case, as shown in FIG. 4, the fuel injection amount in the abnormality occurrence cylinder is unknown. Therefore, before an abnormality occurs in the in-cylinder pressure sensor 21, the fuel injection amount in each cylinder 10 is learned in advance, and the fuel injection amount in the abnormality occurrence cylinder is estimated based on the learning result. Even if an abnormality occurs in one in-cylinder pressure sensor 21, good air-fuel ratio control can be performed.

  In addition, the deviation of the fuel injection amount characteristic in each cylinder 10 is caused by individual differences in the in-cylinder injectors 14 and the state of the nozzles of the in-cylinder injectors 14 (deposits attached). Therefore, unlike the above-described example of in-cylinder intake air amount detection, learning for each operation condition region is not necessary.

  Therefore, the internal combustion engine control device 2 is configured so that when all the in-cylinder pressure sensors 21 are normal, each cylinder has a heat generation amount per unit air amount during steady operation (for example, the throttle valve opening change amount ΔTA <α). Learn a ratio between 10. At this time, the in-cylinder intake air amount for calculating the amount of heat generated per unit air amount may be a value based on the output of the air flow meter 24 or a value obtained by detecting the in-cylinder intake air amount. Also good.

  FIG. 5 is a conceptual diagram showing a specific example when the present invention is applied to EGR rate control. In this case, the system S shown in FIG. 1 includes an EGR passage that connects the surge tank 17a and the exhaust passage 19, and an EGR control valve that is an on-off valve interposed in the EGR passage. Provided.

  Techniques for calculating the EGR rate for each cylinder 10 based on the output of the in-cylinder pressure sensor 21 are known or publicly known (see, for example, Japanese Patent Application Laid-Open Nos. 5-157090, 2008-231995, etc.). This technique calculates the combustion speed or the amount of change in internal energy from the output of the in-cylinder pressure sensor 21, and estimates the in-cylinder EGR rate based on the calculated value.

  At this time, if an abnormality occurs in the in-cylinder pressure sensor 21 corresponding to a certain cylinder 10, the EGR rate in the abnormality occurrence cylinder becomes unknown. However, the main factor in how the EGR gas enters each cylinder 10 is the EGR passage and the piping structure of the intake system. For this reason, a manufacturing error or the like may be included in the manner in which the EGR gas enters each cylinder 10.

  Therefore, by learning the EGR gas introduction characteristics in each cylinder 10 and estimating the EGR rate in the abnormality occurrence cylinder based on the learning result, an abnormality occurs in any one of the in-cylinder pressure sensors 21. In addition, it is possible to perform good EGR control.

  Specifically, the internal combustion engine control device 2 determines the EGR rate of each cylinder 10 when it is determined that the fluctuation of the EGR rate estimated by the in-cylinder pressure sensor 21 is within a certain range under a certain operating condition. The average is calculated, the inter-cylinder deviation is calculated, and the calculated inter-cylinder deviation is stored as a learning value together with the operating conditions (engine speed, air filling rate, etc.).

  The learning value of the inter-cylinder deviation is updated at a predetermined timing. For example, the learning value can be updated at any time for each calculation. Alternatively, the update of the learning value can be permitted at regular intervals (time or travel distance).

  Here, it is assumed that an abnormality occurs in the in-cylinder pressure sensor 21 in the specific cylinder 10 (# 2 cylinder). In this case, as shown in FIG. 5, the EGR rate in the abnormality occurrence cylinder (# 2 cylinder) is not calculated by the output of the in-cylinder pressure sensor 21 corresponding to the abnormality occurrence cylinder.

  Therefore, in this case, the EGR rate calculated based on the output of the in-cylinder pressure sensor 21 of the abnormal cylinder (# 2 cylinder) and the specific normal cylinder (for example, # 1 cylinder) closest to the EGR gas introduction characteristics, and the current operating condition The EGR rate in the cylinder in which an abnormality has occurred can be estimated based on the learned value of the inter-cylinder deviation of the EGR rate at.

  Note that, due to a change in the introduction characteristics of the EGR gas over time, the estimated value of the EGR rate without leaving the abnormality of the in-cylinder pressure sensor 21 in the abnormality-occurring cylinder may not be an appropriate value in the long term. In this case, knocking or misfire occurs in the abnormality occurrence cylinder. Therefore, in this case, it is necessary to prohibit the EGR and prompt the user to check and maintain by notifying the abnormality by a warning light or the like.

  (D) Other modifications not specifically mentioned are naturally included in the scope of the present invention as long as they do not change the essential part of the present invention.

  In addition, in each element constituting the means for solving the problems of the present invention, elements expressed functionally and functionally include the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function.

  Furthermore, the contents (including the specification and the drawings) of each publication cited in this specification can be incorporated as part of this specification.

DESCRIPTION OF SYMBOLS S ... System 1 ... Internal combustion engine CC ... Combustion chamber 10 ... Cylinder 14 ... In-cylinder injector 15 ... Spark plug 2 ... Internal combustion engine controller 20 ... Electronic control unit 21 ... In-cylinder pressure sensor

JP 2006-144642 A JP 2007-40207 A JP 2007-255237 A JP 2008-231995 A JP 2008-297922 A

Claims (4)

The output of the in-cylinder information output unit is a control amount for controlling the combustion state in each cylinder of a multi-cylinder internal combustion engine in which an in-cylinder information output unit that generates an output corresponding to the state in the cylinder is provided for each cylinder. An internal combustion engine control device that controls based on
Learning means for learning the control amount in each cylinder based on outputs from the plurality of in-cylinder information output units;
When an abnormality occurs in any one of the plurality of in-cylinder information output units, the learning is performed on the control amount in the abnormality occurrence cylinder that is a cylinder corresponding to the in-cylinder information output unit in which the abnormality has occurred. An abnormality occurrence cylinder control amount determining means for determining based on a learning result by the means;
An internal combustion engine control device comprising: The internal combustion engine control device according to claim 1,
The abnormality occurrence cylinder control amount determining means determines the control amount in the abnormality occurrence cylinder based on a relative relationship of the control amount between the abnormality occurrence cylinder and a normal cylinder different from the abnormality occurrence cylinder. An internal combustion engine control device characterized by the above. An internal combustion engine control device according to claim 2,
The abnormality occurrence cylinder control amount determination means is based on the relative relationship of the control amount between the abnormality occurrence cylinder and the abnormality occurrence cylinder of the normal cylinder and a reference cylinder that is the closest cylinder to the control amount. An internal combustion engine control device that determines the control amount in the abnormal cylinder. An internal combustion engine control device according to any one of claims 1 to 3,
The internal combustion engine control apparatus according to claim 1, wherein the control amount is an ignition timing that is feedback-controlled based on an output from the in-cylinder information output unit.

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