JP2012225240A - Device for detecting abnormal air-fuel ratio variation among cylinders of multi-cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep vibrations within an acceptable level when a fuel injection amount is decreased for detecting an abnormal condition.SOLUTION: A device for detecting abnormal air-fuel ratio variation among the cylinders of a multi-cylinder internal combustion engine decreases a fuel injection amount of a predetermined target cylinder, and detects abnormal air-fuel ratio variation among the cylinders based on the rotation variation or its correlation value of the target cylinder at least after the fuel is decreased. The device advances the ignition timing of the target cylinder upon decreasing the fuel injection amount.

Description

  The present invention relates to an apparatus for detecting an abnormal variation in the air-fuel ratio between cylinders of a multi-cylinder internal combustion engine, and more particularly to an apparatus for detecting that the air-fuel ratio between cylinders in a multi-cylinder internal combustion engine is relatively large. .

  In general, in an internal combustion engine equipped with an exhaust gas purification system using a catalyst, a mixture ratio of air and fuel in an air-fuel mixture burned in the internal combustion engine, that is, an air-fuel ratio, is used to efficiently remove harmful components in exhaust gas with a catalyst. Control is essential. In order to perform such air-fuel ratio control, an air-fuel ratio sensor is provided in the exhaust passage of the internal combustion engine, and feedback control is performed so that the air-fuel ratio detected thereby coincides with a predetermined target air-fuel ratio.

  On the other hand, in a multi-cylinder internal combustion engine, air-fuel ratio control is normally performed using the same control amount for all cylinders. Therefore, even if air-fuel ratio control is executed, the actual air-fuel ratio may vary between cylinders. If the degree of variation is small at this time, it can be absorbed by air-fuel ratio feedback control, and harmful components in the exhaust gas can be purified by the catalyst, so that exhaust emissions are not affected and there is no particular problem.

  However, for example, if the fuel injection system of some cylinders breaks down and the air-fuel ratio between the cylinders varies greatly, exhaust emission deteriorates, causing a problem. It is desirable to detect such a large air-fuel ratio variation that deteriorates the exhaust emission as an abnormality. In particular, in the case of an internal combustion engine for automobiles, it is required to detect an abnormal variation in air-fuel ratio between cylinders in an in-vehicle state in order to prevent the vehicle from traveling with deteriorated exhaust emissions (so-called OBD; On-Board Diagnostics). .

  For example, in the apparatus described in Patent Document 1, when it is determined that an air-fuel ratio abnormality has occurred in any of the cylinders, the fuel injected into each cylinder until the cylinder in which the air-fuel ratio abnormality has occurred is misfired. The injection time is reduced by a predetermined time, thereby identifying the abnormal cylinder.

JP 2010-112244 A

  By the way, when an air-fuel ratio abnormality occurs in any of the cylinders, if the fuel injection amount of the cylinder is forcibly reduced, the rotational fluctuation of the cylinder may be significantly increased. Therefore, it is possible to detect an abnormality in the air-fuel ratio variation by detecting this increase in rotational fluctuation.

  However, when the fuel injection amount is reduced with respect to a normal cylinder in which no air-fuel ratio abnormality has occurred, the rotational fluctuation does not fall outside the allowable level, but the vibration may fall outside the allowable level. The fuel injection amount reduction for detecting an abnormality is overwhelmingly more performed on the normal cylinder than on the abnormal cylinder. For this reason, it is important to suppress the vibration when the fuel injection amount is reduced within an allowable level.

  Accordingly, the present invention was created in view of the above circumstances, and its purpose is to achieve an inter-cylinder air-fuel ratio of a multi-cylinder internal combustion engine that can suppress vibrations within a permissible level when reducing the fuel injection amount for detecting an abnormality. The object is to provide a variation abnormality detection device.

According to one aspect of the invention,
An abnormality detecting means for reducing a fuel injection amount of a predetermined target cylinder and detecting an air-fuel ratio variation abnormality between cylinders based on at least the rotational fluctuation of the target cylinder after the reduction or a correlation value thereof;
Advancing means for advancing the ignition timing of the target cylinder when the fuel injection amount is reduced by the abnormality detecting means;
An inter-cylinder air-fuel ratio variation abnormality detecting device for a multi-cylinder internal combustion engine is provided.

  Preferably, the advance means changes the advance amount of the ignition timing in accordance with a parameter representing the operating state of the internal combustion engine.

  Preferably, the abnormality detecting means changes a fuel injection amount reduction amount according to a parameter representing an operating state of the internal combustion engine.

  According to the present invention, an excellent effect is exhibited in that vibration when the fuel injection amount reduction for abnormality detection is performed can be suppressed within an allowable level.

1 is a schematic view of an internal combustion engine according to an embodiment of the present invention. It is a graph which shows the output characteristic of a pre-catalyst sensor and a post-catalyst sensor. It is a time chart for demonstrating the value showing rotation fluctuation. It is a time chart for demonstrating another value showing rotation fluctuation. It is a graph which shows the change of rotation fluctuation when fuel injection quantity is increased or decreased. It is a graph which shows a mode when weight reduction is performed in the area | region where the imbalance rate is negative among FIG. It is a flowchart of a variation abnormality detection routine. It is a graph which shows the in-cylinder pressure diagram at the time of normal and abnormal. It is a graph which mainly shows the influence of the ignition timing advance with respect to the in-cylinder pressure diagram at normal time. It is a graph which shows the ion current diagram at the time of normal and abnormal. It is a graph which mainly shows the influence of the ignition timing advance angle with respect to the ion current diagram in normal time.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows an internal combustion engine according to this embodiment. An illustrated internal combustion engine (engine) 1 is a V-type 8-cylinder spark ignition internal combustion engine (gasoline engine) mounted on an automobile. The engine 1 has a first bank B1 and a second bank B2, and the first bank B1 is provided with odd-numbered cylinders, that is, # 1, # 3, # 5, and # 7 cylinders. B2 is provided with even-numbered cylinders, that is, # 2, # 4, # 6, and # 8 cylinders. The # 1, # 3, # 5, and # 7 cylinders form the first cylinder group, and the # 2, # 4, # 6, and # 8 cylinders form the second cylinder group.

  Each cylinder is provided with an injector (fuel injection valve) 2. The injector 2 injects fuel into the intake passage of the corresponding cylinder, particularly into an intake port (not shown). Each cylinder is provided with a spark plug 13 for igniting the air-fuel mixture in the cylinder.

  The intake passage 7 for introducing the intake air includes a surge tank 8 as a collective portion, a plurality of intake manifolds 9 connecting the intake ports of each cylinder and the surge tank 8, and the upstream side of the surge tank 8. Of the intake pipe 10. The intake pipe 10 is provided with an air flow meter 11 and an electronically controlled throttle valve 12 in order from the upstream side. The air flow meter 11 outputs a signal having a magnitude corresponding to the intake flow rate.

  A first exhaust passage 14A is provided for the first bank B1, and a second exhaust passage 14B is provided for the second bank B2. The first and second exhaust passages 14 </ b> A and 14 </ b> B are joined on the upstream side of the downstream catalyst 19. Since the structure of the exhaust system upstream of the merge position is the same in both banks, only the first bank B1 side will be described here, and the second bank B2 side will be given the same reference numeral in the drawing and description thereof will be omitted. To do.

  The first exhaust passage 14A includes exhaust ports (not shown) of the cylinders # 1, # 3, # 5, and # 7, an exhaust manifold 16 that collects exhaust gases of these exhaust ports, and an exhaust manifold 16 And an exhaust pipe 17 installed on the downstream side. The exhaust pipe 17 is provided with an upstream catalyst 18. A pre-catalyst sensor 20 and a post-catalyst sensor 21 that are air-fuel ratio sensors for detecting the air-fuel ratio of the exhaust gas are installed on the upstream side and the downstream side (immediately and immediately after) of the upstream catalyst 18, respectively. Thus, one upstream catalyst 18, one before catalyst 20 and one after catalyst 21 are provided for each of a plurality of cylinders (or one cylinder group) belonging to one bank.

  In addition, it is also possible to provide the downstream catalyst 19 separately in these, without making the 1st and 2nd exhaust passage 14A, 14B merge.

  The engine 1 is provided with an electronic control unit (hereinafter referred to as ECU) 100 as a control means. The ECU 100 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like, all not shown. In addition to the air flow meter 11, the pre-catalyst sensor 20 and the post-catalyst sensor 21, the ECU 100 includes a crank angle sensor 22 for detecting the crank angle of the engine 1 and an accelerator opening sensor 23 for detecting the accelerator opening. The water temperature sensor 24 for detecting the temperature of the engine cooling water and other various sensors are electrically connected via an A / D converter or the like (not shown). The ECU 100 controls the injector 2, spark plug 13, throttle valve 12, etc. so as to obtain a desired output based on detection values of various sensors and the like, and controls the fuel injection amount, fuel injection timing, ignition timing, throttle opening degree. Control etc.

  The throttle valve 12 is provided with a throttle opening sensor (not shown), and a signal from the throttle opening sensor is sent to the ECU 100. The ECU 100 normally feedback-controls the opening of the throttle valve 12 (throttle opening) to an opening determined according to the accelerator opening.

  Further, the ECU 100 detects the amount of intake air per unit time, that is, the amount of intake air based on the signal from the air flow meter 11. The ECU 100 detects the load of the engine 1 based on at least one of the detected accelerator opening, throttle opening, and intake air amount. The load may be detected based on the intake pressure.

  The ECU 100 detects the crank angle itself and the rotational speed of the engine 1 based on the crank pulse signal from the crank angle sensor 22. Here, “the number of rotations” means the number of rotations per unit time and is synonymous with the rotation speed. In the present embodiment, it means rpm per minute.

  The pre-catalyst sensor 20 is a so-called wide-range air-fuel ratio sensor, and can continuously detect an air-fuel ratio over a relatively wide range. FIG. 2 shows the output characteristics of the pre-catalyst sensor 20. As shown in the figure, the pre-catalyst sensor 20 outputs a voltage signal Vf having a magnitude proportional to the detected exhaust air-fuel ratio (pre-catalyst air-fuel ratio A / Ff). The output voltage when the exhaust air-fuel ratio is stoichiometric (theoretical air-fuel ratio, for example, A / F = 14.5) is Vreff (for example, about 3.3 V).

  On the other hand, the post-catalyst sensor 21 is a so-called O2 sensor and has a characteristic that the output value changes suddenly at the stoichiometric boundary. FIG. 2 shows the output characteristics of the post-catalyst sensor 21. As shown in the figure, the output voltage when the exhaust air-fuel ratio (post-catalyst air-fuel ratio A / Fr) is stoichiometric, that is, the stoichiometric equivalent value is Vrefr (for example, 0.45 V). The output voltage of the post-catalyst sensor 21 changes within a predetermined range (for example, 0 to 1 V). Generally, when the exhaust air-fuel ratio is leaner than stoichiometric, the output voltage Vr of the post-catalyst sensor is lower than the stoichiometric equivalent value Vrefr. When the exhaust air-fuel ratio is richer than stoichiometric, the output voltage Vr of the post-catalyst sensor is higher than the stoichiometric equivalent value Vrefr. Get higher.

  The upstream catalyst 18 and the downstream catalyst 19 are made of a three-way catalyst, and simultaneously purify NOx, HC and CO, which are harmful components in the exhaust gas, when the air-fuel ratio A / F of the exhaust gas flowing into each of them is near the stoichiometric. The air-fuel ratio width (window) that can simultaneously purify these three with high efficiency is relatively narrow.

  Therefore, during normal operation of the engine, the ECU 100 executes air-fuel ratio control (stoichiometric control) for controlling the air-fuel ratio of the exhaust gas flowing into the upstream catalyst 18 in the vicinity of the stoichiometric. In this air-fuel ratio control, the air-fuel ratio of the air-fuel mixture (specifically, the fuel injection amount) is feedback-controlled so that the exhaust air-fuel ratio detected by the pre-catalyst sensor 20 becomes a stoichiometric value that is a predetermined target air-fuel ratio. Fuel ratio control (main air-fuel ratio feedback control) and auxiliary air-fuel ratio control that feedback-controls the air-fuel ratio (specifically, fuel injection amount) of the air-fuel mixture so that the exhaust air-fuel ratio detected by the post-catalyst sensor 21 becomes stoichiometric. (Auxiliary air-fuel ratio feedback control).

  Thus, in the present embodiment, the reference value of the air-fuel ratio is stoichiometric, and the fuel injection amount corresponding to this stoichiometric (referred to as stoichiometric equivalent amount) is the reference value of the fuel injection amount. However, the reference values for the air-fuel ratio and the fuel injection amount may be other values.

  The air-fuel ratio control is performed on a bank basis or on a bank basis. For example, the detection values of the pre-catalyst sensor 20 and the post-catalyst sensor 21 on the first bank B1 side are used only for air-fuel ratio feedback control of the # 1, # 3, # 5, and # 7 cylinders belonging to the first bank B1. This is not used for the air-fuel ratio feedback control of the # 2, # 4, # 6, and # 8 cylinders belonging to the second bank B2. The reverse is also true. Air-fuel ratio control is executed as if there were two independent in-line four-cylinder engines. In the air-fuel ratio control, the same control amount is uniformly used for each cylinder belonging to the same bank.

  For example, in some cylinders (particularly one cylinder) of all the cylinders, a failure of the injector 2 or the like may occur, and variations in air-fuel ratio (imbalance) may occur between the cylinders. For example, for the first bank B1, the fuel injection amount of the # 1 cylinder becomes larger than the fuel injection amounts of the other # 3, # 5, and # 7 cylinders due to poor closing of the injector 2, and the air-fuel ratio of the # 1 cylinder is This is a case where the air-fuel ratio of the other # 3, # 5, and # 7 cylinders is greatly shifted to the rich side.

  Even at this time, if a relatively large correction amount is given by the above-described air-fuel ratio feedback control, the air-fuel ratio of the total gas (exhaust gas after joining) supplied to the pre-catalyst sensor 20 may sometimes be stoichiometrically controlled. However, looking at each cylinder, # 1 cylinder is larger and richer than stoichiometric, and # 3, # 5, and # 7 cylinders are leaner than stoichiometric. Is clear. In view of this, the present embodiment is equipped with a device that detects such a variation in air-fuel ratio between cylinders.

  Here, a value that is an imbalance rate is used as an index value that represents the degree of variation in the air-fuel ratio between cylinders. The imbalance rate is the ratio of the fuel injection amount of the cylinder (imbalance cylinder) causing the fuel injection amount deviation when only one cylinder among the plurality of cylinders causes the fuel injection amount deviation. Thus, it is a value indicating whether or not there is a deviation from the fuel injection amount of the cylinder (balance cylinder) in which the fuel injection amount deviation has not occurred, that is, the reference injection amount. When the imbalance rate is IB (%), the fuel injection amount of the imbalance cylinder is Qib, and the fuel injection amount of the balance cylinder, that is, the reference injection amount is Qs, IB = (Qib−Qs) / Qs × 100. The greater the imbalance rate IB, the greater the fuel injection amount deviation between the imbalance cylinder and the balance cylinder, and the greater the air-fuel ratio variation.

  On the other hand, in the present embodiment, the fuel injection amount of a predetermined target cylinder is actively or forcibly changed (increased or reduced), and at least based on the rotational fluctuation of the target cylinder after the change (increased or decreased), variation abnormality Is detected.

  First, rotational fluctuation will be described. The rotational fluctuation means a change in the engine rotational speed or the crankshaft rotational speed, and can be expressed by, for example, the following values. In this embodiment, the rotation fluctuation for each cylinder can be detected.

  FIG. 3 shows a time chart for explaining the rotation fluctuation. The illustrated example is an example of an in-line four-cylinder engine, but it will be understood that the present invention can also be applied to a V-type eight-cylinder engine as in this embodiment. The firing order is the order of # 1, # 3, # 4, and # 2 cylinders.

  In FIG. 3, (A) shows the crank angle (° CA) of the engine. One engine cycle is 720 (° CA), and the crank angle for a plurality of cycles detected sequentially is shown in a sawtooth shape in the figure.

  (B) shows the time required for the crankshaft to rotate by a predetermined angle, that is, the rotation time T (s). Here, the predetermined angle is 30 (° CA), but may be another value (for example, 10 (° CA)). The longer the rotation time T, the slower the engine rotation speed. Conversely, the shorter the rotation time T, the faster the engine rotation speed. The rotation time T is detected by the ECU 100 based on the output of the crank angle sensor 22.

  (C) shows a rotation time difference ΔT described later. In the figure, “normal” indicates a normal case in which no air-fuel ratio shift occurs in any cylinder, and “lean shift abnormality” indicates, for example, the imbalance rate IB = −30 (% ) Indicates an abnormal case where lean deviation occurs. The lean deviation abnormality can be caused by, for example, clogging of an injector nozzle hole or a poor valve opening.

  First, the rotation time T at the same timing of each cylinder is detected by the ECU. Here, the rotation time T at the timing of compression top dead center (TDC) of each cylinder is detected. The timing at which the rotation time T is detected is referred to as detection timing.

  Next, at each detection timing, the ECU calculates a difference (T2−T1) between the rotation time T2 at the detection timing and the rotation time T1 at the immediately preceding detection timing. This difference is a rotation time difference ΔT shown in (C), and ΔT = T2−T1.

  Usually, the rotational speed increases in the combustion stroke after the crank angle of a certain cylinder exceeds TDC, and therefore the rotational time T decreases. In the subsequent compression stroke of the next cylinder, the rotational speed decreases and the rotational time T increases. .

However, as shown in (B), when the # 1 cylinder has an abnormal lean shift, even if the # 1 cylinder is ignited, a sufficient torque cannot be obtained and the rotational speed is difficult to increase. The rotation time T is increased. Therefore, the rotation time difference ΔT in the # 3 cylinder TDC is a large positive value as shown in (C). The rotation time and rotation time difference in the # 3 cylinder TDC are defined as the rotation time and rotation time difference of the # 1 cylinder, respectively, and are represented by T ₁ and ΔT ₁ , respectively. The same applies to the other cylinders.

Next, since the # 3 cylinder is normal, when the # 3 cylinder is ignited, the rotational speed increases sharply. As a result, at the timing of the next # 4 cylinder TDC, the rotation time T is only slightly reduced compared to that of the # 3 cylinder TDC. Therefore, the rotation time difference ΔT ₃ of the # 3 cylinder detected in the # 4 cylinder TDC is a small negative value as shown in (C). Thus, the rotation time difference ΔT of a certain cylinder is detected for each next ignition cylinder TDC.

In the subsequent # 2 cylinder TDC and # 1 cylinder TDC, the same tendency as in the case of the # 4 cylinder TDC is observed, and the rotation time difference ΔT ₄ of the # ₄ cylinder and the rotation time difference ΔT ₂ of the # 2 cylinder detected at both timings. Both are small negative values. The above characteristics are repeated every engine cycle.

  Thus, it can be seen that the rotation time difference ΔT of each cylinder is a value representing the rotation fluctuation of each cylinder, and is a value correlated with the air-fuel ratio deviation amount of each cylinder. Therefore, the rotation time difference ΔT of each cylinder can be used as an index value of the rotation fluctuation of each cylinder. As the air-fuel ratio deviation amount of each cylinder increases, the rotational fluctuation of each cylinder increases and the rotation time difference ΔT of each cylinder increases.

  On the other hand, as shown in FIG. 3C, in the normal case, the rotation time difference ΔT is always near zero.

  In the example of FIG. 3, the case of the lean deviation abnormality is shown. However, the reverse tendency of the rich deviation, that is, the case where a large rich deviation occurs in only one cylinder has the same tendency. This is because when a large rich shift occurs, combustion is insufficient due to excessive fuel even when ignited, and sufficient torque cannot be obtained, resulting in large rotational fluctuations.

  Next, another value representing the rotation variation will be described with reference to FIG. (A) shows the crank angle (° CA) of the engine as in FIG. 3 (A).

  (B) shows the angular velocity ω (rad / s) which is the reciprocal of the rotation time T. ω = 1 / T. As a matter of course, the larger the angular velocity ω, the faster the engine rotational speed, and the smaller the angular velocity ω, the slower the engine rotational speed. The waveform of the angular velocity ω has a shape obtained by vertically inverting the waveform of the rotation time T.

  (C) shows the angular velocity difference Δω, which is the difference in angular velocity ω, as with the rotation time difference ΔT. The waveform of the angular velocity difference Δω also has a shape obtained by vertically inverting the waveform of the rotation time difference ΔT. “Normal” and “lean deviation abnormality” in the figure are the same as those in FIG.

  First, the angular velocity ω at the same timing of each cylinder is detected by the ECU. Again, the angular velocity ω at the timing of compression top dead center (TDC) of each cylinder is detected. The angular velocity ω is calculated by dividing 1 by the rotation time T.

  Next, at each detection timing, the ECU calculates a difference (ω2−ω1) between the angular velocity ω2 at the detection timing and the angular velocity ω1 at the immediately preceding detection timing. This difference is the angular velocity difference Δω shown in (C), and Δω = ω2−ω1.

  Normally, the rotational speed increases in the combustion stroke after the crank angle of a certain cylinder exceeds TDC, so the angular speed ω increases. In the subsequent compression stroke of the next cylinder, the rotational speed decreases, so the angular speed ω decreases.

However, as shown in (B), when the # 1 cylinder has an abnormal lean shift, even if the # 1 cylinder is ignited, a sufficient torque cannot be obtained and the rotational speed is difficult to increase. The angular velocity ω at is small. Therefore, the angular velocity difference Δω in the # 3 cylinder TDC is a large negative value as shown in (C). The angular velocity and the angular velocity difference in the # 3 cylinder TDC are the angular velocity and the angular velocity difference of the # 1 cylinder, respectively, and are represented by ω ₁ and Δω ₁ , respectively. The same applies to the other cylinders.

Next, since the # 3 cylinder is normal, when the # 3 cylinder is ignited, the rotational speed increases sharply. As a result, at the timing of the next # 4 cylinder TDC, the angular velocity ω is only slightly increased compared to that of the # 3 cylinder TDC. Therefore, the angular velocity difference Δω ₃ of the # 3 cylinder detected in the # 4 cylinder TDC is a small positive value as shown in (C). Thus, the angular velocity difference Δω of a certain cylinder is detected for each subsequent ignition cylinder TDC.

Subsequent # 2 cylinder TDC and # 1 cylinder also seen the same tendency as in the case of the fourth cylinder TDC at TDC, the angular velocity difference [Delta] [omega ₄ and # 2 cylinder of the detected # 4 cylinder in both timing angular difference [Delta] [omega ₂ Both are small positive values. The above characteristics are repeated every engine cycle.

  Thus, it can be seen that the angular velocity difference Δω of each cylinder is a value representing the rotational fluctuation of each cylinder and is a value correlated with the air-fuel ratio deviation amount of each cylinder. Therefore, the angular velocity difference Δω of each cylinder can be used as an index value of the rotation fluctuation of each cylinder. As the air-fuel ratio deviation amount of each cylinder increases, the rotational fluctuation of each cylinder increases, and the angular velocity difference Δω of each cylinder decreases (increases in the minus direction).

  On the other hand, as shown in FIG. 4C, in the normal case, the angular velocity difference Δω is always near zero.

  As described above, there is a similar tendency in the case of reverse rich shift abnormality.

  Next, changes in rotational fluctuation when the fuel injection amount of one cylinder is actively increased or decreased will be described with reference to FIG.

  In FIG. 5, the horizontal axis indicates the imbalance rate IB, and the vertical axis indicates the angular velocity difference Δω as an index value of rotational fluctuation. Here, the imbalance rate IB of only one cylinder among all eight cylinders is changed, and the relationship between the imbalance rate IB of the one cylinder and the angular velocity difference Δω of the one cylinder at this time is indicated by a line a. The one cylinder is referred to as an active target cylinder. All the other cylinders are balance cylinders, and the stoichiometric equivalent amount is injected as the reference injection amount Qs.

  On the horizontal axis, IB = 0 (%) means a normal case where the imbalance ratio IB of the active target cylinder is 0 (%) and the active target cylinder is injecting a stoichiometric amount. The data at this time is indicated by plot b on line a. When moving from the state of IB = 0 (%) to the left side in the figure, the imbalance rate IB increases in the positive direction, and the fuel injection amount becomes excessive, that is, a rich state. On the contrary, when moving from IB = 0 (%) to the right side in the figure, the imbalance rate IB increases in the minus direction, and the fuel injection amount becomes too small, that is, a lean state.

  As can be seen from the characteristic line a, even if the imbalance ratio IB of the active target cylinder increases in the positive direction from 0 (%) or increases in the negative direction, the rotation fluctuation of the active target cylinder increases, and the active target cylinder increases. The angular velocity difference Δω tends to increase in the minus direction from near zero. As the imbalance rate IB increases from 0 (%), the slope of the characteristic line a becomes steeper, and the change in the angular velocity difference Δω with respect to the change in the imbalance rate IB tends to increase.

  Here, as indicated by an arrow c, it is assumed that the fuel injection amount of the active target cylinder is forcibly increased from the stoichiometric amount (IB = 0 (%)) by a predetermined amount. In the illustrated example, the imbalance rate is increased by approximately 40 (%). At this time, since the slope of the characteristic line a is gentle in the vicinity of IB = 0 (%), the angular velocity difference Δω remains substantially unchanged even after the increase, and the difference between the angular velocity differences Δω before and after the increase is extremely small. .

  On the other hand, as shown by plot d, consider a case where a rich shift has already occurred in the active target cylinder and the imbalance rate IB has a relatively large positive value. In the illustrated example, a rich shift of about 50 (%) occurs in the imbalance rate. As indicated by an arrow e from this state, if the fuel injection amount of the active target cylinder is forcibly increased by the same amount, the slope of the characteristic line a is steep in this region, so the angular velocity difference Δω after the increase is increased. Changes to the minus side largely before the increase, and the difference in angular velocity difference Δω before and after the increase becomes larger. In other words, the rotational fluctuation of the active target cylinder increases as the fuel injection amount increases.

  Therefore, it is possible to detect a variation abnormality based on at least the angular velocity difference Δω of the active target cylinder after the increase when the fuel injection amount of the active target cylinder is forcibly increased by a predetermined amount.

  That is, when the angular velocity difference Δω after the increase is smaller than a predetermined negative abnormality determination value α as shown in the figure (Δω <α), it is determined that there is a variation abnormality and the active target cylinder is identified as an abnormal cylinder. Can do. Conversely, if the angular velocity difference Δω after the increase is not smaller than the abnormality determination value α (Δω ≧ α), at least the active target cylinder can be determined to be normal.

  Alternatively, as shown in the drawing, it is possible to detect a variation abnormality based on the difference dΔω of the angular velocity difference Δω before and after the increase. In this case, if the angular velocity difference before the increase is Δω1 and the angular velocity difference after the increase is Δω2, the difference dΔω can be defined as dΔω = Δω1−Δω2. When the difference dΔω exceeds a predetermined positive abnormality determination value β1 (dΔω> β1), it can be determined that there is a variation abnormality, and the active target cylinder can be identified as an abnormal cylinder. Conversely, when the difference dΔω does not exceed the abnormality determination value β1 (dΔω ≦ β1), at least the active target cylinder can be determined to be normal.

  The same can be said when forced reduction is performed in a region where the imbalance rate is negative. As indicated by an arrow f, it is assumed that the fuel injection amount of the active target cylinder is forcibly reduced by a predetermined amount from the stoichiometric amount (IB = 0 (%)). In the illustrated example, the imbalance rate is reduced by about 10%. The reason why the amount of reduction is smaller than the amount of increase is that if too much weight reduction is performed on the lean deviation abnormal cylinder, a misfire will occur. At this time, since the slope of the characteristic line a is relatively gradual, the angular velocity difference Δω after the decrease is only slightly smaller than before the decrease, and the difference between the angular velocity differences Δω before and after the increase is small.

  On the other hand, as shown by the plot g, let us consider a case where a lean shift has already occurred in the active target cylinder and the imbalance rate IB has a relatively large negative value. In the illustrated example, a lean shift of about −20 (%) occurs in the imbalance rate. As indicated by the arrow h from this state, if the fuel injection amount of the active target cylinder is forcibly reduced by the same amount, the slope of the characteristic line a is relatively steep in this region. The difference Δω is greatly changed to the minus side before the weight reduction, and the difference between the angular velocity differences Δω before and after the weight reduction becomes large. That is, the rotational fluctuation of the active target cylinder increases due to the decrease in the fuel injection amount.

  Therefore, it is possible to detect a variation abnormality based on at least the angular velocity difference Δω of the active target cylinder after the reduction when the fuel injection amount of the active target cylinder is forcibly reduced by a predetermined amount.

  That is, if the angular velocity difference Δω after the reduction is smaller than a predetermined negative abnormality determination value α as shown in the figure (Δω <α), it is determined that there is a variation abnormality and the active target cylinder is identified as an abnormal cylinder. Can do. Conversely, if the angular velocity difference Δω after the reduction is not smaller than the abnormality determination value α (Δω ≧ α), at least the active target cylinder can be determined to be normal.

  Alternatively, as shown in the drawing, it is possible to detect a variation abnormality based on the difference dΔω of the angular velocity difference Δω before and after the weight reduction. Also in this case, the difference dΔω between them can be defined as dΔω = Δω1−Δω2. When the difference dΔω exceeds a predetermined positive abnormality determination value β2 (dΔω> β2), it can be determined that there is a variation abnormality and the active target cylinder can be identified as an abnormal cylinder. Conversely, when the difference dΔω does not exceed the abnormality determination value β2 (dΔω ≦ β2), at least the active target cylinder can be determined to be normal.

  Here, since the increase amount is significantly larger than the decrease amount, the abnormality determination value β1 at the time of increase is made larger than the abnormality determination value β2 at the time of decrease. However, both abnormality determination values can be arbitrarily determined in consideration of the characteristics of the characteristic line a and the balance between the increase amount and the decrease amount. Both abnormality determination values can be set to the same value.

  It will be understood that when the rotation time difference ΔT is used as an index value of the rotation fluctuation of each cylinder, it is possible to detect an abnormality and specify an abnormal cylinder by the same method. Further, other values than those described above can be used as the index value of the rotational fluctuation of each cylinder.

  As a method of increasing or decreasing the fuel injection amount, there are a method in which all the cylinders are simultaneously performed and a method in which a predetermined number of cylinders are sequentially and alternately performed. For example, there is a method of increasing the amount by one cylinder, increasing the amount by two cylinders, or increasing the amount by four cylinders. The number of cylinders to be increased and the cylinder number can be arbitrarily set.

  As the number of target cylinders increases, there is a merit that the detection time can be shortened, and there is a demerit that exhaust emission deteriorates. Conversely, the smaller the number of target cylinders, there is a merit that deterioration of exhaust emission can be suppressed, but there is a demerit that the detection time is prolonged.

  The above is the outline of variation abnormality detection in this embodiment.

  By the way, when the fuel injection amount is reduced with respect to the normal cylinder, although the rotational fluctuation does not reach the allowable level, the vibration may go out of the allowable level. The fuel injection amount reduction for detecting an abnormality is overwhelmingly more performed on the normal cylinder than on the abnormal cylinder. For this reason, it is important to suppress the vibration when the fuel injection amount is reduced within an allowable level.

  This point will be described with reference to FIG. FIG. 6 shows a state when forced reduction is performed in the region where the imbalance rate is negative in FIG. The same parts as those in FIG.

  As described above, even if the fuel injection amount of the active target cylinder is forcibly reduced from the stoichiometric amount (IB = 0 (%)) by a predetermined amount as indicated by the arrow f, the angular velocity difference Δω after the reduction is an abnormality determination value. α does not exceed Δω <α. Further, the difference dΔω in the angular velocity difference before and after the weight loss does not exceed β2, and dΔω> β2 is not satisfied. This means that even if the weight is reduced with respect to the normal cylinder, it does not fall outside the allowable level from the viewpoint of rotational fluctuation. Although the plot b changes to the plot l, the plot l does not exceed the abnormality determination value α that is the limit value of the allowable level of rotational fluctuation.

  However, from the standpoint of the engine itself and the vibration of the vehicle, the permissible level of rotational fluctuation becomes more severe. The limit value of the permissible level is γ shown in the figure, which is on the normal side with respect to the previous abnormality determination value α. γ is called the vibration limit. The region where the rotational fluctuation is below the vibration limit γ, that is, the region where Δω ≧ γ is the allowable level of vibration. However, when the rotational fluctuation exceeds the vibration limit γ, that is, when the region reaches Δω <γ, the vibration is out of the allowable level.

  The plot l exceeds the vibration limit γ, and Δω <γ in the plot l. Therefore, the vibration is outside the allowable level.

  The difference between the abnormality determination value α and the vibration limit γ is based on the following reason. The abnormality determination value α is a value determined based on the OBD regulation value from the viewpoint of exhaust emission, whereas the vibration limit γ is a value determined based on the vibration noise requirements of the engine and the vehicle from the viewpoint of comfort. is there.

  As shown in FIG. 5, when comparing the positive region and the negative region of the imbalance rate, the slope of the characteristic line a is larger in the negative region than in the positive region. Therefore, in the negative region, the degree of deterioration in rotational fluctuation is greater when the fuel injection amount is changed by a fixed amount than in the positive region, and this also makes it easier to exceed the vibration limit γ when the normal cylinder is reduced. .

  The amount of weight reduction for abnormality detection is overwhelmingly higher than that for abnormal cylinders. This is because, in many cases, all cylinders are normal for a long time from a new time, and only when one cylinder becomes abnormal due to deterioration over time or the like, the weight reduction is performed for the abnormal cylinder. It is rare that a plurality of cylinders become abnormal at the same time, and normally, the cylinders become abnormal in order one by one. If an abnormality in one cylinder is detected, necessary repairs such as replacement of the injector are performed, so that the original state of all cylinders immediately returns to normal. Therefore, the weight reduction is performed again for all normal cylinders.

  Therefore, the weight reduction is frequently performed on the normal cylinder every time detection is performed at a predetermined frequency. It is important to take measures so that the actual vibration does not exceed the vibration limit at each frequent weight loss.

  Therefore, in the present embodiment, in order to overcome such a problem, when the fuel injection amount is reduced with respect to the active target cylinder, the ignition timing is also advanced. If the ignition timing is advanced, combustion at the time of weight reduction is improved, and deterioration of rotational fluctuation is reduced. Therefore, it is possible to suppress the vibration when the amount is reduced with respect to the normal cylinder within an allowable level.

  This point will be described with reference to FIG. When the ignition timing is advanced, the characteristic line a is changed to an advance characteristic line a ′ indicated by an imaginary line, and the slope of the characteristic line in a predetermined region from zero to a small negative value is obtained. It becomes more gradual. Therefore, when the amount is reduced with respect to the normal cylinder, the plot b changes to the plot l ′, and the plot l ′ does not exceed the vibration limit γ. In the plot l ′, Δω ≧ γ, and the vibration is suppressed within an allowable level.

  On the other hand, when the imbalance rate is more negative than the predetermined region, the advance characteristic line a ′ is steeper than the reference characteristic line a, approaches the reference characteristic line a, and eventually matches. To do. In the vicinity of the imbalance rate (plot g) before the abnormal cylinder is reduced, the advance characteristic line a 'is very close to the reference characteristic line a. This means that when the original air-fuel ratio is largely deviated as in an abnormal cylinder, there is almost no combustion improvement effect even if the ignition timing is advanced. Accordingly, even if the abnormal cylinder is reduced and the ignition timing is advanced, the rotational fluctuation before and after the reduction is almost the same as when the ignition timing is not advanced.

  Utilizing the above characteristics, in this embodiment, variation abnormality detection is executed as follows.

  FIG. 7 shows a variation abnormality detection routine. This routine is repeatedly executed by the ECU 100 at every predetermined calculation cycle.

  Here, the cycle counter value Ci and the cylinder counter value Cj, which are internal values of the ECU 100, are used. The initial value of the cycle counter value Ci is 0, and the initial value of the cylinder counter value Cj is 1. j is a cylinder number, and j = 1, 2,.

  First, in step S101, it is determined whether a predetermined precondition for performing abnormality detection is satisfied. For example, (1) the engine is in a warm-up state, (2) the upstream catalyst 18 and the downstream catalyst 19 are in a warm-up state, (3) the engine is in a steady operation state, and (4) the stoichiometric control is being executed. The precondition is satisfied. The success or failure of the condition (1) is determined based on the detection value of the water temperature sensor 24. For example, if the detection value is 75 ° C. or higher, the condition is satisfied. The success or failure of the condition (2) is determined based on the upstream catalyst temperature and the downstream catalyst temperature separately detected or estimated. The success or failure of the condition (3) is determined, for example, based on whether or not the fluctuation range of the intake air amount Ga and the engine speed Ne within a predetermined period is within a predetermined range. The intake air amount Ga is detected by the air flow meter 5, and the engine speed Ne is calculated from the output of the crank angle sensor 14. Other examples of the precondition are possible.

  If the precondition is not satisfied, the process is terminated. On the other hand, if the precondition is satisfied, the process proceeds to step S102.

  In step S102, a fuel reduction amount ΔQ (> 0) when the fuel injection amount is reduced is calculated. This fuel reduction amount ΔQ is changed in accordance with a parameter (referred to as an engine parameter) representing the operating state of the engine. For example, the engine parameter is composed of the rotational speed and the load, and a fuel reduction amount ΔQ corresponding to the actually detected rotational speed and the load is calculated from a predetermined map (which may be a function, the same applies hereinafter). The fuel reduction amount ΔQ is changed according to the rotation speed and the load. The fuel reduction amount ΔQ has a value such that the fuel injection amount Q after the reduction (step S104) corresponds to a predetermined negative imbalance rate.

  Next, in step S103, an ignition timing advance amount ΔIG (> 0) at the time of ignition timing advance performed simultaneously with the fuel injection amount decrease is calculated. This ignition timing advance amount ΔIG is also changed according to the engine parameter. For example, as described above, the engine parameter includes the rotation speed and the load, and the ignition timing advance amount ΔIG corresponding to the actually detected rotation speed and the load is calculated from a predetermined map. The ignition timing advance amount ΔIG is changed according to the rotation speed and the load.

  In step S104, the fuel injection amount Q after the reduction when the fuel injection amount is reduced is calculated. The post-reduction fuel injection amount Q is calculated from the equation: Q = Qb−ΔQ. Qb is a basic injection amount, which is a predetermined value so that the air-fuel mixture in the cylinder is stoichiometric when the operating condition is constant. The basic injection amount Qb is calculated from a predetermined map based on actually detected engine parameters (for example, rotation speed and load). Naturally, the basic injection amount Qb is also changed according to the engine parameter. During the execution of this routine (that is, during the execution of variation abnormality detection), the stoichiometric control is stopped, and the fuel injection amount is actively controlled by the open control.

  In step S105, the ignition timing IG after advance is calculated. This post-advance ignition timing IG is calculated from the formula: IG = IGb−ΔIG. IGb is a basic ignition timing, and is a value determined in advance so as to be almost MBT (optimum ignition timing) when the operating condition is constant. The basic ignition timing IGb is calculated from a predetermined map based on actually detected engine parameters (for example, rotation speed and load). Naturally, the basic ignition timing IGb is also changed according to the engine parameters.

  In step S106, the fuel of the reduced fuel injection amount Q is actually injected from the injector 2 at a predetermined fuel injection timing. In step S107, actual ignition by the spark plug 13 is executed at the post-advance ignition timing IG.

  In step S108, the angular velocity difference Δωi after reduction, which is an index value of rotational fluctuation, is detected and stored.

  In step S109, the cycle counter value Ci is incremented by 1 (incremented).

  In step S110, it is determined whether or not the cycle counter value Ci has reached a predetermined value I (for example, 100) or more. If not reached, the process ends. If reached, the process proceeds to step S111.

  In step S111, an average value of the I stored angular velocity differences Δωi is calculated, and this average value is stored as the angular velocity difference Δωj of the #j cylinder.

  In step S112, the cylinder counter value Cj is incremented by 1 (incremented).

  In step S113, it is determined whether or not the cylinder counter value Cj has reached the same value J (here, 8) as the number of cylinders. If not reached, the process ends. If reached, the process proceeds to step S114.

  As can be seen from the above description, first, fuel injection amount reduction and ignition timing advance are executed for the # 1 cylinder (Cj = 1), and I angular velocity differences Δωi at this time are acquired. The average value is stored as the angular velocity difference Δωj of the # 1 cylinder. Next, the same processing is executed for the # 2 cylinder (Cj = 2). Thereafter, the same processing is executed sequentially for # 3 cylinder, # 4 cylinder,..., And finally the angular velocity difference Δωj of all 8 cylinders is detected and stored.

  Here, the amount is decreased from the # 1 cylinder in the order of the cylinder numbers, but the order of the decrease may not be the same as the order of the cylinder numbers. Although the amount is reduced by one cylinder here, it is possible to reduce the amount by a plurality of cylinders (for example, two or four cylinders) or to reduce all the cylinders simultaneously. The number and cylinder number of the target cylinders to be reduced can be arbitrarily set.

  Next, in step S114, the angular velocity difference Δωj of each cylinder is compared with the negative abnormality determination value α. If the angular velocity difference Δωj of all the cylinders is equal to or greater than the abnormality determination value α, it is determined in step S115 that there is no variation abnormality, that is, normal, and the routine is terminated.

  On the other hand, when the angular velocity difference Δωj of any cylinder (for convenience, the #j cylinder) is smaller than the abnormality determination value α, it is determined in step S116 that there is a variation abnormality, specifically, that the #j cylinder has a lean deviation abnormality. The routine is terminated.

  The variation abnormality detection can be performed only in a relatively narrow operation region (for example, an idle operation region). In this case, a condition that the engine parameter is within such a predetermined operation region is included in the precondition of step S101. In addition, the fuel reduction amount ΔQ and the ignition timing advance amount ΔIG can be set to constant values without being variable. As a result, steps S102 and S103 can be omitted for simplification.

  Alternatively, as shown in FIG. 6, the variation abnormality detection may be performed only in the operation region where the characteristic line changes significantly from a to a ′ when the ignition timing is advanced.

  Further, instead of the rotation fluctuation as described in the above embodiment, a correlation value of the rotation fluctuation can be used.

  In-cylinder pressure can be used as a first example of a correlation value of rotational fluctuations. In this case, the in-cylinder pressure of each cylinder is detected by an in-cylinder pressure sensor provided individually for each cylinder.

  In FIG. 8, “normal” indicates an in-cylinder pressure diagram when normal, and “abnormal” indicates an in-cylinder pressure diagram when lean deviation is abnormal. As shown in the figure, in a certain cylinder, combustion becomes worse as the lean deviation becomes larger with reference to the normal in-cylinder pressure diagram in which no air-fuel ratio deviation has occurred. Therefore, the in-cylinder pressure diagram moves to the low pressure side. The maximum peak of in-cylinder pressure (indicated by P only when normal) tends to decrease. The maximum peak of in-cylinder pressure correlates with the rotation fluctuation, and the rotation fluctuation is larger as the maximum peak is smaller.

  Therefore, for example, it is possible to reduce the fuel injection amount of the active target cylinder and detect an air-fuel ratio deviation abnormality based on at least the in-cylinder pressure of the active target cylinder or the maximum peak after the reduction. In other words, if the in-cylinder pressure or its maximum peak exceeds a predetermined value, the active target cylinder is determined to be normal, and if the in-cylinder pressure or its maximum peak does not exceed a predetermined value, the active target cylinder is determined to be abnormal. It is also possible to detect an abnormality in the air-fuel ratio deviation based on the maximum peak decrease amount before and after the decrease.

  Alternatively, instead of the maximum peak of the in-cylinder pressure, it is also possible to use an in-cylinder pressure integrated value (area) within a predetermined period Δθ before and after the maximum peak. If the in-cylinder pressure integrated value is equal to or greater than a predetermined value, the active target cylinder is determined to be normal, and if the in-cylinder pressure integrated value is not equal to or greater than the predetermined value, the active target cylinder is determined to be abnormal. It is also possible to detect an air-fuel ratio deviation abnormality based on the amount of decrease in the in-cylinder pressure integrated value before and after the decrease.

  Here, as shown in FIG. 9, the in-cylinder pressure diagram at normal time is lowered to the diagram b if the ignition timing advance is not performed when the fuel injection amount is decreased, but the ignition timing advance is performed when the fuel injection amount is decreased. And the amount of decrease up to the diagram a. Therefore, by performing the ignition timing advance when reducing the fuel injection amount as in the present embodiment, it is possible to suppress the deterioration of rotational fluctuation when the normal cylinder is reduced, and to suppress the vibration during the reduction to an allowable level.

  Note that, as shown in FIG. 9, the in-cylinder pressure diagram at the time of abnormality hardly changes regardless of whether or not the ignition timing advance is performed together with the fuel injection amount reduction.

  Next, an ion current can be used as a second example of the correlation value of the rotational fluctuation. In this case, the ion current in each cylinder is detected by an ion current sensor provided for each cylinder individually. The ionic current is generated in the combustion chamber after the ignition of the air-fuel mixture, and the value becomes larger as the combustion state is better.

  In FIG. 10, “normal” indicates an ionic current diagram when normal, and “abnormal” indicates an ionic current diagram when lean deviation is abnormal. As shown in the figure, in one cylinder, since the combustion becomes worse as the lean deviation increases with reference to the normal ionic current diagram in which no air-fuel ratio deviation has occurred, the ionic current diagram moves to the decreasing side. However, the maximum peak of the ionic current (indicated by P ′ only when normal) tends to decrease. The maximum peak of the ion current correlates with the rotation fluctuation, and the rotation fluctuation is larger as the maximum peak is smaller.

  Therefore, for example, it is possible to reduce the fuel injection amount of the active target cylinder and detect an air-fuel ratio deviation abnormality based on at least the ion current of the active target cylinder after the reduction or the maximum peak thereof. That is, the active target cylinder is determined to be normal if the ionic current or its maximum peak exceeds a predetermined value, and the active target cylinder is determined to be abnormal if the ionic current or its maximum peak does not exceed the predetermined value. It is also possible to detect an abnormality in the air-fuel ratio deviation based on the maximum peak decrease amount before and after the decrease.

  Alternatively, instead of the maximum peak of the ion current, it is also possible to use an ion current integrated value (area) within a predetermined period Δθ before and after the maximum peak. If the ion current integrated value is equal to or greater than a predetermined value, the active target cylinder is determined to be normal, and if the ion current integrated value is not equal to or greater than the predetermined value, the active target cylinder is determined to be abnormal. It is also possible to detect an air-fuel ratio deviation abnormality based on the amount of decrease in the integrated ion current value before and after the decrease.

  Here, as shown in FIG. 11, the ionic current diagram at normal time is greatly reduced to the diagram d if the ignition timing advance is not performed when the fuel injection amount is decreased, but the ignition timing advance is performed when the fuel injection amount is decreased. If it does, it will stop at the small fall amount to the diagram c. Therefore, by performing the ignition timing advance when reducing the fuel injection amount as in the present embodiment, it is possible to suppress the deterioration of rotational fluctuation when the normal cylinder is reduced, and to suppress the vibration during the reduction to an allowable level.

  As shown in FIG. 11, the ionic current diagram at the time of abnormality does not substantially change whether the ignition timing advance is performed or not performed together with the fuel injection amount reduction.

  The preferred embodiment of the present invention has been described in detail above, but various other embodiments of the present invention are conceivable. For example, instead of using the difference dΔω between the angular velocity difference Δω1 before the increase and the angular velocity difference Δω2 after the increase, the ratio between the two can be used. The same applies to the difference in angular velocity difference dΔω before and after the decrease, or the difference in rotation time difference ΔT before and after the increase or decrease. The present invention is not limited to a V-type 8-cylinder engine but can be applied to engines of various other types and the number of cylinders. As the post-catalyst sensor, a wide air-fuel ratio sensor similar to the pre-catalyst sensor may be used.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 Internal combustion engine
2 Injector 11 Air flow meter 12 Throttle valve 13 Spark plug 18 Upstream catalyst 20 Pre-catalyst sensor 22 Crank angle sensor 23 Accelerator opening sensor 100 Electronic control unit (ECU)

Claims (3)

An abnormality detecting means for reducing a fuel injection amount of a predetermined target cylinder and detecting an air-fuel ratio variation abnormality between cylinders based on at least the rotational fluctuation of the target cylinder after the reduction or a correlation value thereof;
Advancing means for advancing the ignition timing of the target cylinder when the fuel injection amount is reduced by the abnormality detecting means;
An inter-cylinder air-fuel ratio variation abnormality detecting device for a multi-cylinder internal combustion engine, comprising: 2. The abnormality detection of variation in air-fuel ratio between cylinders of a multi-cylinder internal combustion engine according to claim 1, wherein the advance means changes an advance amount of ignition timing in accordance with a parameter representing an operating state of the internal combustion engine. apparatus. 3. The air-fuel ratio variation among cylinders of a multi-cylinder internal combustion engine according to claim 1, wherein the abnormality detection unit changes a reduction amount of the fuel injection amount in accordance with a parameter representing an operating state of the internal combustion engine. Anomaly detection device.

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