JP5742787B2 - Abnormal combustion detection device for internal combustion engine - Google Patents

Description

  The present invention relates to an abnormal combustion detection device for an internal combustion engine. More specifically, the present invention relates to an abnormal combustion detection device applied to an internal combustion engine having an in-cylinder pressure sensor for detecting a pressure in a cylinder of the internal combustion engine.

  Patent Document 1 discloses a first value based on the in-cylinder pressure predicted from a physical model representing the progress of the pressure of each cylinder of the internal combustion engine, and the output of an in-cylinder pressure sensor installed for each of a plurality of cylinders. A system is disclosed in which the value of 2 is compared, and when the difference between the two is equal to or greater than a predetermined value, it is determined that the combustion is abnormal in the internal combustion engine.

  Japanese Patent Application Laid-Open No. 2004-26883 discloses detection of abnormal combustion of an internal combustion engine, obtaining a combustion state amount of each cylinder according to the output of an in-cylinder pressure sensor, detecting abnormal combustion, and regulating abnormal combustion.

JP 2010-071284 A JP 2007-231948 A JP 2008-524489 A JP 2005-330904 A

  In Patent Document 1, the presence or absence of abnormal combustion is determined based on the deviation of the parameter based on the output of the in-cylinder pressure sensor with respect to the value calculated from the physical model. As described above, the system that detects abnormal combustion based on the output of the in-cylinder pressure sensor may erroneously determine abnormal combustion when the in-cylinder pressure sensor causes output drift or sensitivity abnormality.

  Further, as in Patent Document 2, a system that determines the presence or absence of abnormal combustion based on the combustion state quantity cannot correctly grasp the combustion state quantity when the in-cylinder pressure sensor causes output drift, There is a risk of misjudgment.

  An object of the present invention is to solve the above-described problems, and to detect abnormal combustion of an internal combustion engine with high accuracy while suppressing erroneous determination of abnormal combustion when an in-cylinder pressure sensor causes output drift and / or sensitivity abnormality. The present invention provides an abnormal combustion detection device for an internal combustion engine improved so as to be able to do so.

In order to achieve the above object, the present invention is applied to an internal combustion engine having an in-cylinder pressure sensor that generates an output in accordance with the pressure in the combustion chamber of the internal combustion engine. This abnormal combustion detection device for an internal combustion engine has a means for acquiring an output drift amount of the in-cylinder pressure sensor in accordance with an output of the in-cylinder pressure sensor, and a specific combustion in accordance with the output drift amount and the output of the in-cylinder pressure sensor. Means for estimating the crank angle reaching the mass ratio and means for detecting abnormal combustion in accordance with the estimated crank angle. The means for estimating the crank angle is a means for calculating a calculated value of the crank angle that reaches a specific combustion mass ratio according to the output of the in-cylinder pressure sensor, and a specific combustion mass ratio is reached according to the output drift amount. And means for estimating an angle shift of a calculated value of the crank angle with respect to the actual crank angle. Further, the means for estimating the crank angle includes means for correcting the calculated value of the crank angle in accordance with the angle deviation, and the corrected calculated value is set as a crank angle that reaches a specific combustion mass ratio.

In order to achieve the above object, the present invention is applied to an internal combustion engine having an in-cylinder pressure sensor that generates an output corresponding to the pressure in the combustion chamber of the internal combustion engine. This abnormal combustion detection device for an internal combustion engine has a means for acquiring an output drift amount of the in-cylinder pressure sensor in accordance with an output of the in-cylinder pressure sensor, and a specific combustion in accordance with the output drift amount and the output of the in-cylinder pressure sensor. Means for estimating the crank angle reaching the mass ratio and means for detecting abnormal combustion in accordance with the estimated crank angle. The means for detecting abnormal combustion detects abnormal combustion in accordance with the angle difference between the crank angle that reaches a specific combustion mass ratio and the ignition timing of the cylinder.

  In the present invention, a combustion mass ratio of 50% may be a specific combustion mass ratio.

In the present invention, the means for obtaining the output drift amount is an output of the in - cylinder pressure sensor detected before the intake valve closing timing of the cylinder and an output of the in - cylinder pressure sensor detected after the exhaust valve opening timing of the cylinder. The output drift amount may be calculated according to the difference.

  The crank angle that reaches the specific combustion mass ratio can be calculated using the output of the in-cylinder pressure sensor. However, when output drift occurs in the in-cylinder pressure sensor, the value of the crank angle that reaches the calculated specific combustion mass ratio is different from the actual value. In the present invention, this angle shift corresponds to the output drift amount of the in-cylinder pressure sensor, so that a specific combustion mass ratio is reached according to both the output drift amount and the output of the in-cylinder pressure sensor. A crank angle is obtained, and the presence or absence of abnormal combustion is determined according to the obtained crank angle. Accordingly, even when output drift occurs in the in-cylinder pressure sensor, it is possible to determine the presence or absence of abnormal combustion with high accuracy.

  Further, when a sensitivity abnormality occurs in the in-cylinder pressure sensor, the detected value of the in-cylinder pressure based on the output of the in-cylinder pressure sensor is detected as a whole smaller value than the actual value. However, even if the in-cylinder pressure itself decreases due to an abnormality in sensitivity, the influence on the calculated value of the crank angle with respect to the combustion mass ratio is small. In the present invention, the crank angle that reaches a specific combustion mass ratio that is less affected by the abnormality in sensitivity of the in-cylinder pressure sensor is used as a parameter, so that even when a further abnormality in sensitivity occurs in the in-cylinder pressure sensor, the accuracy is high. The presence or absence of combustion abnormality can be determined.

  In addition, the influence of sensitivity abnormality on the calculated value of the crank angle at which the combustion mass ratio reaches 50% is particularly small. Therefore, in the case of detecting abnormal combustion by obtaining the crank angle when the combustion mass ratio is 50%, even if both the output drift and sensitivity abnormality occur in the in-cylinder pressure sensor, the accuracy is further increased. The presence or absence of abnormal combustion can be determined.

It is a schematic diagram for demonstrating the whole structure of the system in embodiment of this invention. It is a figure showing the change of the cylinder pressure detection value based on the output of the cylinder pressure sensor in embodiment of this invention. It is a figure showing the change of the cylinder pressure detection value based on the output of the cylinder pressure sensor in embodiment of this invention. It is a figure showing the change of the cylinder pressure detection value based on the output of the cylinder pressure sensor in embodiment of this invention. It is a figure for demonstrating the variation | change_quantity of the emitted-heat amount calculated in embodiment of this invention. It is a figure for demonstrating the change of the combustion mass ratio calculated in embodiment of this invention. It is a figure for demonstrating the relationship between the calculated value of the crank angle which reaches | attains the combustion mass ratio 50% in embodiment of this invention, and the output drift amount of a cylinder pressure sensor. It is a figure for demonstrating correction | amendment with respect to the calculated value of the crank angle which reaches | attains the combustion mass ratio 50% in embodiment of this invention. It is a flowchart for demonstrating the routine of control which a control apparatus performs in embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.
Embodiment 1 FIG.

[System Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining the overall configuration of the system according to the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes a spark ignition type internal combustion engine 2 used as a power source for a vehicle.

  The internal combustion engine 2 has a plurality of cylinders 4, and FIG. 1 shows a cross section of one of the cylinders. Each cylinder 4 is provided with a piston 6. The piston 6 is connected to the crankshaft via a crank mechanism. A crank angle sensor 8 is provided in the vicinity of the crankshaft. The crank angle sensor 8 is a sensor that generates an output corresponding to the rotation angle of the crankshaft.

  Each cylinder 4 is provided with a spark plug 14 and a CPS 16 (Combustion Pressure Sensor) for igniting the air-fuel mixture in the combustion chamber of the cylinder 4. The CPS 16 is an in-cylinder pressure sensor that generates an output corresponding to the pressure in the combustion chamber (in-cylinder pressure).

  The system according to the first embodiment includes a control device 20. In addition to the crank angle sensor 8 and the CPS 16, various sensors such as a water temperature sensor, an air flow meter, a throttle position sensor, and an air-fuel ratio sensor are connected to the input side of the control device 20. In addition to the spark plug 14 described above, various actuators are connected to the output side of the control device 20. The control device 20 controls the operation state of the internal combustion engine 2 by executing predetermined programs based on input information from various sensors and operating various actuators.

[Detection of Abnormal Combustion in Embodiment]
The control executed by the control device 20 in the first embodiment includes control for abnormal combustion detection, and the control device 20 functions as an abnormal combustion detection device for the internal combustion engine 2.

  Abnormal combustion occurring in each cylinder 4 of the internal combustion engine can be detected based on the progress of combustion in the combustion chamber. The progress state of combustion is predicted by detecting the time when a specific combustion mass ratio (hereinafter also referred to as “MFB”) is reached. MFB is a value representing the ratio of the burned fuel out of the fuel flowing into the cylinder.

  In the present embodiment, a specific MFB is set to 50%, a crank angle reaching the MFB 50% (hereinafter also referred to as “CA50”) is detected, and an angle between the detected CA50 and a crank angle corresponding to the ignition timing. Find the difference. In the control of the internal combustion engine 2, since the ignition timing is controlled so that CA50 becomes a predetermined crank angle, the angle difference between the crank angle of ignition timing and CA50 is constant. On the other hand, when abnormal combustion occurs, the CA50 is accelerated and the angular difference from the CA50 is reduced.

  Therefore, in the present embodiment, when the calculated angular difference between CA50 and ignition timing (CA50−ignition timing) is smaller than the first reference value α, it is determined that abnormal combustion has occurred, and abnormal Detect combustion. The first reference value α is appropriately set according to the angle difference between the CA50 in normal combustion and the crank angle at the ignition timing. Specific values are set in advance through experiments, simulations, and the like, and stored in the control device 20.

[Characteristic control of the first embodiment]
By the way, as for the CA50, the in-cylinder pressure corresponding to the output of the CPS 16 is estimated. Therefore, when an abnormality occurs in the CPS 16 and a deviation occurs between the in-cylinder pressure detection value and the actual detection value, the estimated CA50 value may be affected. This will be described below. In this embodiment, the term “in-cylinder pressure detection value” refers to the in-cylinder pressure detected based on the output of the CPS 16.

<About CPS16 sensitivity abnormality>
FIG. 2 is a diagram illustrating a change in the in-cylinder pressure detection value in the present embodiment. In FIG. 2, the horizontal axis represents the crank angle [deg], and the vertical axis represents the in-cylinder pressure [MPa]. In FIG. 2, the line (a) is the in-cylinder pressure detection value when the CPS 16 is normal, and the line (b) is the in-cylinder pressure detection value when the CPS 16 has a sensitivity abnormality.

  As shown by the line (b) in FIG. 2, when the sensitivity abnormality occurs in the CPS 16, the output is small, and the in-cylinder pressure detection value is generally smaller than the actual in-cylinder pressure. However, the in-cylinder pressure detection value decreases at a substantially uniform rate, and for example, there is no deviation in the crank angle indicating the maximum in-cylinder pressure.

<About the output drift amount of CPS16>
Further, when a crack or the like occurs in the element in the CPS 16, an output drift in which the output fluctuates occurs, and the in-cylinder pressure detection value may be different from the actual in-cylinder pressure. 3 and 4 are diagrams showing changes in the in-cylinder pressure detection value based on the output of the CPS 16 in the present embodiment. 3 and 4, the horizontal axis represents the crank angle [deg], and the vertical axis represents the in-cylinder pressure [MPa]. In FIG. 3, the line (a) is the in-cylinder pressure detection value when the CPS 16 is normal, and the line (b) is the in-cylinder pressure detection value when the CPS 16 is causing output drift.

  As shown in FIG. 3, the deviation between the in-cylinder pressure detection value when the CPS 16 is causing the output drift and the in-cylinder pressure detection value when the CPS 16 is normal is particularly large after the angle at which the in-cylinder pressure becomes maximum. The in-cylinder pressure detection value when the output drift is generated is significantly larger than the normal in-cylinder pressure detection value.

  Here, if the CPS 16 is normal, as shown in the line (a), the in-cylinder pressure and the exhaust valve opening timing (hereinafter also referred to as “EVO”) before the intake valve closing timing (hereinafter also referred to as “IVC”). Subsequent in-cylinder pressure is substantially the same. However, when the CPS 16 causes output drift, the in-cylinder pressure after EVO does not show a value that matches the in-cylinder pressure detection value before IVC, and the in-cylinder pressure detection value before IVC and the in-cylinder pressure detection value after EVO. Deviation occurs between Therefore, in the present embodiment, as shown in FIG. 4, the difference between the in-cylinder pressure detection value in EVO and the in-cylinder pressure detection value in IVC is obtained as the output drift amount of CPS 16.

<Effect of output drift on combustion mass ratio>
Next, the effect of the deviation of the in-cylinder pressure detection value on the calculated CA50 value when output drift occurs in the CPS 16 will be described.

上記式（１）において、Ｑ_ｉは燃焼開始からある時点ｉまでに生じた発熱量であり、Ｑ_ｉｖｃは、ＩＶＣまでに生じた発熱量、Ｑ_ｍａｘは今回の燃焼サイクルでの総発熱量である。 First, MFB _i at a certain time point i is calculated by the following equation (1).

In the above formula (1), Q _i is a calorific value generated from the start of combustion to a certain time point i, Q _ivc is a calorific value generated until IVC, and Q _max is a total calorific value in the current combustion cycle. is there.

上記式（２）において、θ_ｉはある時点ｉにおけるクランク角である。 A calorific value Q _i at a certain time point i caused by combustion of each cylinder 4 is calculated according to the following equation (2).

In the above formula (2), θ _i is a crank angle at a certain time point i.

上記式（３）において、κは比熱比、Ｐ_ｉは時点ｉにおける筒内圧検出値、Ｖ_ｉは時点ｉにおける燃焼室容積である。発熱量Ｑ_ｉの変移量（ｄＱ/ｄθ_ｉ）は、あるクランク角θ_ｉで単位時間に発生した発熱量である。 Further, the change (dQ / dθ _i ) in the calorific value Q _i is obtained by the following equation (3).

In the above equation (3), κ is the specific heat ratio, P _i is the in-cylinder pressure detection value at time point i, and V _i is the combustion chamber volume at time point i. The change amount (dQ / dθ _i ) of the heat generation amount Q _i is the heat generation amount generated per unit time at a certain crank angle θ _i .

FIG. 5 is a view for explaining the calorific value variation dQ / dθ _i calculated in the embodiment of the present invention. In FIG. 5, the horizontal axis represents the crank angle [deg], and the vertical axis represents the calorific value variation dQ / dθ _i [J]. Line (a) shows the case where CPS 16 does not cause output drift, and line (b) shows the case where CPS 16 causes output drift.

As shown in the equations (2) and (3), the calorific value Q _i and its displacement dQ / dθ _i are calculated using the in-cylinder pressure detection value P _i . If the output drift CPS16 does not occur, as shown in line (a), displacement amount dQ / d [theta] _i of the heating value indicates the smaller becomes finally zero at a relatively early stage.

On the other hand, when the output drift occurs in the CPS 16, the value of the in-cylinder pressure detection value Pi indicates a maximum in-cylinder pressure and then a value larger than the actual in-cylinder pressure. Due to this influence, the calorific value variation dQ / dθ _i calculated by the equation (3) also becomes large, and even if the actual amount of variation reaches a crank angle near zero, the calorific value variation calculated is Indicates a large value.

For this reason, when the output drift occurs in the CPS 16, the calorific value Q _i calculated by the equation (2) continues to increase. As a result, the time (crank angle) indicating the maximum heat generation amount _Qmax is greatly deviated toward the retard side.

FIG. 6 is a diagram showing a change in MFB calculated according to the equation (1) in the present embodiment. In FIG. 6, the horizontal axis represents the crank angle [deg], and the vertical axis represents MFB [%]. As described above, when the output drift occurs, the position (crank angle) of the total calorific value _Qmax is greatly shifted to the retard side. MFB indicates the heat generation amount Q _i up to the present with respect to the total heat generation amount Q _max , and thus means the ratio of the current heat generation amount when Q _max is 100 [%].

CPS16 to cause output drift, the crank angle indicating the total calorific value Q _max is, when it is actually calculated offset retarded than the crank angle indicating the total calorific value Q _max, the line shown in FIG. 6 (b) as shown, for example, the calorific value Q _i is the calculated value of the CA50 which is 50% of gross calorific value Q _max also becomes in comparison with the actual CA50, it deviated largely retarded side.

<About correction of CA50>
As described above, in the present embodiment, the presence or absence of abnormal combustion is determined based on the angle difference between CA50 and the crank angle of the ignition timing. Therefore, in order to correctly determine the presence or absence of abnormal combustion, it is necessary to remove the influence of the output drift on the calculated CA50. Therefore, in the present embodiment, the calculated value of CA50 is corrected as follows.

  As described above, the amount of shift to the retard side that occurs in the combustion mass ratio MFBi is caused by output drift. That is, the amount of deviation between the actual MFBi value (line (a)) and the calculated value of MFBi (line (b)) as shown in FIG. 6 has a correlation with the output drift amount. The amount of deviation (angle deviation) of the value from the actual CA50 has a correlation with the output drift amount.

  FIG. 7 is a diagram for explaining the relationship between the amount of deviation included in the calculated value of CA50 and the amount of output drift. In FIG. 7, the horizontal axis represents the output drift amount [MPa], and the vertical axis represents the CA50 deviation amount [deg]. As shown in FIG. 7, as the output drift amount increases, the CA50 deviation amount also increases.

  Further, the relationship between the output drift amount and the CA50 deviation amount as shown in FIG. 7 is also affected by the operating conditions of the internal combustion engine 2 such as a load, and the output drift amount with respect to the CA50 deviation amount depends on the operating state. The degree of contribution will be different.

  Therefore, in the present embodiment, the relationship between the output drift amount and the CA50 deviation amount as shown in FIG. 7 is obtained in advance by experiment, simulation, calculation, etc. for each predetermined operating condition. And the like are stored in the control device 20.

  FIG. 8 is a diagram for explaining correction for CA50 in the embodiment of the present invention. In FIG. 8, the crank angle [deg] and the vertical axis represent MFB [%]. In FIG. 8, the line (a) indicates the MFB value calculated when the CPS 16 does not cause output drift, and the line (b) indicates the MFB value calculated when the CPS 16 causes output drift. Line (c) represents the value of MFB when CA50 is corrected.

  In actual control during operation of the internal combustion engine 2, an output drift amount is calculated, and a deviation amount corresponding to the output drift amount is obtained according to a map corresponding to the operation condition at that time. As shown by the line (b) in FIG. 8, the calculated deviation amount is used as a correction value, and the CA50 is corrected by subtracting it from the CA50 calculated based on the in-cylinder pressure detection value (advanced by the deviation amount). To do. Thereby, CA50 in which the influence of the output drift of the CPS 16 is compensated is obtained.

  The control device 20 determines a combustion abnormality using the CA50 corrected in this way. Therefore, erroneous determination due to the influence of the output drift of the CPS 16 can be suppressed, and the presence or absence of abnormal combustion can be determined with high accuracy.

As described with reference to FIG. 2, when the sensitivity abnormality occurs in the CPS 16, the in-cylinder pressure detection value becomes smaller at a substantially uniform rate as a whole. Thus, the impact on the calculated value of the crank angle calorific value becomes maximum calorific value Q _max is small, therefore less abnormal sensitivity influence on calculation values of CA50. Therefore, in this embodiment, if the influence due to the output drift is compensated, abnormal combustion can be detected with high accuracy even if sensitivity abnormality occurs in the CPS 16.

  FIG. 9 is a flowchart for illustrating a control routine executed by control device 20 in the embodiment of the present invention. The routine of FIG. 9 is a routine that is repeatedly executed at a constant calculation cycle during operation of the internal combustion engine 2.

  When the routine of FIG. 9 is started, first, the CA50 for the current combustion cycle is calculated (S100). CA50 is calculated by a predetermined arithmetic expression in accordance with the in-cylinder pressure detection value detected based on the output of the CPS 16 obtained by the control device 20.

  Next, an output drift amount is calculated (S102). The output drift amount is obtained as a difference between the in-cylinder pressure detection value in IVC and the in-cylinder pressure detection value in EVO.

  Next, it is determined whether or not the calculated output drift amount is larger than the second reference value β (S104). Here, the second reference value β is a reference value stored in the control device in advance. For example, the second reference value β is set to a value near the upper limit of the allowable range for the difference in the in-cylinder pressure detection value between IVC and EVO. Is done. By this determination, it is determined whether or not an output drift requiring correction is generated in the CPS 16.

  In step S104, when the establishment of the output drift amount> β is recognized, it is determined that the CPS 16 has generated the output drift. In this case, the deviation amount at CA50 is then calculated (S106). The relationship between the deviation amount and the output drift amount in CA50 is stored in advance in the control device 20 as a map or an arithmetic expression. Accordingly, here, the amount of deviation is calculated according to the output drift amount obtained in step S102, according to the map corresponding to the current operating state.

  Next, the crank angle of CA50 is corrected according to the amount of deviation (S108). Specifically, in S100, the crank angle of CA50 calculated based on the output of CPS 16 is advanced according to the amount of deviation calculated in step S106.

  If the crank angle of CA50 is corrected in step S108, or if the establishment of the output drift amount> β is not recognized in step S104, then the process of step S110 is performed. That is, the angle difference between the crank angle of the ignition timing and CA50 is calculated. Here, the crank angle of the ignition timing is an angle appropriately set in another routine according to the current operating state. When the crank angle of CA50 is corrected in step S108, the corrected crank angle of CA50 is used, and when it is not corrected (when the output drift amount ≦ β), it is calculated in step S100. The crank angle of CA50 is used as it is.

  Next, it is determined whether or not the angle difference between the ignition timing and CA50 is smaller than the first reference value α (S112). The first reference value α is a value serving as a reference value for determining whether or not abnormal combustion has occurred, and is a value stored in the control device 20 in advance.

  If it is determined in step S112 that the angle difference <the first reference value α is established, it is determined that abnormal combustion has occurred, and the current routine ends. If it is determined that there is abnormal combustion, necessary control set in a separate routine is executed, such as a warning light indicating abnormal combustion this time, or predetermined control for eliminating abnormal combustion.

  On the other hand, if the establishment of the angular difference <the first reference value α is not recognized in step S112, it is determined that the combustion is normal, and the current process ends.

  As described above, according to the present embodiment, even when output drift occurs in the CPS 16, the CA50 from which the influence is removed can be obtained, and thereby the presence or absence of abnormal combustion can be determined. Therefore, even when output drift occurs in the CPS 16, it is possible to suppress erroneous determination of abnormal combustion and detect abnormal combustion with high accuracy.

  Further, in the present embodiment, abnormal combustion can be detected using as a parameter CA50 that is not susceptible to CPS16 sensitivity abnormality. Therefore, even if sensitivity abnormality occurs in CPS 16 in addition to output drift, erroneous determination of abnormal combustion due to sensitivity abnormality can be suppressed.

  In the present embodiment, the case where abnormal combustion is determined using CA50 as a parameter has been described. However, the present invention is not limited to this. As described above, the crank angle reaching a specific MFB is calculated using the in-cylinder pressure detection value, and when the output drift occurs in the CPS 16, the output drift is a crank reaching a specific MFB. The calculated angle value is deviated from the actual crank angle. This deviation amount has a correlation with the output drift amount. Therefore, not only when the MFB is 50 [%], but also when the crank angle with respect to another MFB is used as a parameter, the relationship between the output drift and the amount of deviation generated in the crank angle of the MFB should be obtained in advance. Thus, the same control as described above can be performed.

  In the present embodiment, the case has been described in which the output drift amount is obtained as the difference between the in-cylinder pressure detection values in IVC and EVO. However, the present invention is not limited to this, and the output drift amount may be detected by other methods. Further, other parameters having a correlation with the output drift amount can be used instead of the output drift amount.

  In the present embodiment, the case where abnormal combustion is detected using the angle difference between the crank angle of CA50 and the crank angle corresponding to the ignition timing as a parameter has been described. However, the present invention is not limited to the one based on the ignition timing, and may be any one that detects abnormal combustion according to the crank angle with respect to a specific MFB.

  In the present embodiment, CA50 is corrected in step S104 on the assumption that output drift has occurred only when the output drift amount is larger than the second reference value β. However, the present invention is not limited to this, and for example, a deviation amount corresponding to the output drift amount may be calculated and corrected regardless of the magnitude of the output drift amount.

  Further, in the present embodiment, a case has been described in which, after CA50 is first calculated, a correction amount (deviation amount) corresponding to the output drift amount is obtained to correct CA50. However, in the present invention, the method for estimating the crank angle for a specific MFB is not limited to this, and any method may be used as long as the output drift of the CPS 16 is taken into consideration. Therefore, for example, the crank angle that reaches a specific MFB may be estimated directly from the output drift amount and the in-cylinder pressure detection value. When the crank angle is directly estimated in this way, for example, the relationship between the output drift amount, the in-cylinder pressure detection value, and the crank angle (for example, CA50) reaching a specific MFB is simulated in advance for each operating condition. And is stored in the control device 20 as a map or the like. According to this map, in actual control, the crank angle can be estimated according to the output drift amount and the in-cylinder pressure detection value.

  In the present embodiment, the processing in step S102 is executed, thereby realizing the “means for obtaining the output drift amount” of the present invention, and the processing in steps S100, S106, and S108 is executed. The “means for estimating the crank angle” is realized, and the “means for detecting abnormal combustion” is realized by executing the processing of steps S112 to S116. Further, the “means for calculating the calculated value of the crank angle” of the present invention is realized by executing the processing of step S100, and the “means for estimating the angle deviation” is realized by executing the processing of step S106. This is realized, and the “correcting means” is realized by executing the process of step S108. That is, in the present invention, the control device 20 includes means for estimating the output drift amount, means for estimating the crank angle (including means for calculating the calculated value of the crank angle, means for estimating the angle deviation, and means for correcting), and Means for detecting abnormal combustion is included as part of its function.

  In the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., the reference is made unless otherwise specified or the number is clearly specified in principle. The invention is not limited to the numbers. The structures, steps, and the like described in this embodiment are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

2 Internal combustion engine 4 cylinder 16 CPS (in-cylinder pressure sensor)
20 Control device

Claims (4)

Means for obtaining an output drift amount of the in-cylinder pressure sensor in response to an output of the in-cylinder pressure sensor that generates an output corresponding to the pressure in the cylinder of the internal combustion engine;
Means for estimating a crank angle that reaches a specific combustion mass ratio in accordance with the output drift amount and the output of the in-cylinder pressure sensor;
Means for detecting abnormal combustion according to the crank angle estimated by the means for estimating ,
The means for estimating the crank angle includes:
Means for calculating a calculated value of a crank angle that reaches the specific combustion mass ratio according to an output of the in-cylinder pressure sensor;
Means for estimating an angular shift of a calculated value of the crank angle with respect to an actual crank angle that reaches the specific combustion mass ratio according to the output drift amount;
Means for correcting the calculated value of the crank angle according to the angular deviation,
An abnormal combustion detection device for an internal combustion engine, wherein the calculated value corrected by the correcting means is a crank angle that reaches the specific combustion mass ratio .   Means for obtaining an output drift amount of the in-cylinder pressure sensor in response to an output of the in-cylinder pressure sensor that generates an output corresponding to the pressure in the cylinder of the internal combustion engine;
  Means for estimating a crank angle that reaches a specific combustion mass ratio in accordance with the output drift amount and the output of the in-cylinder pressure sensor;
  Means for detecting abnormal combustion according to the crank angle estimated by the means for estimating,
  The means for detecting abnormal combustion detects the abnormal combustion according to an angle difference between a crank angle estimated by the means for estimating the crank angle and an ignition timing of the cylinder. Abnormal combustion detection device.   The abnormal combustion detection device for an internal combustion engine according to claim 1 or 2, wherein a combustion mass ratio of 50% is set as the specific combustion mass ratio. The means for acquiring the output drift amount includes an output of the in-cylinder pressure sensor detected before the intake valve closing timing of the cylinder, and an output of the in-cylinder pressure sensor detected after the exhaust valve opening timing of the cylinder. The abnormal combustion detection device for an internal combustion engine according to any one of claims 1 to 3, wherein the output drift amount is calculated in accordance with a difference between the two.

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