JP4251028B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus for an internal combustion engine that determines a fuel property based on a combustion state of the internal combustion engine and changes control specifications related to combustion of the internal combustion engine to reflect the determination result.
[0002]
[Prior art]
Fuels for internal combustion engines include light fuels with high volatility and heavy fuels with low volatility, and the combustion state of the internal combustion engine changes depending on the properties of these fuels. In view of this, there is known an apparatus that determines the properties of fuel and changes the control parameters used for operation control of the internal combustion engine based on the determination result.
[0003]
For example, in the devices described in Patent Document 1 and Patent Document 2, the fuel property is determined based on the rotational fluctuation of the internal combustion engine in which the combustion state is reflected, and the fuel injection amount corresponding to the determined fuel property is set. I have to.
[0004]
[Patent Document 1]
JP-A-8-86237
[Patent Document 2]
JP-A-8-284708
[Patent Document 3]
JP-A-4-213057
[0005]
[Problems to be solved by the invention]
By the way, the combustion state changes depending on various factors other than the fuel properties. Therefore, when determining the fuel property based on the combustion state, there is a possibility that the determination of the fuel property may be mistaken when the combustion state changes due to factors other than the fuel property, and the reliability of the determination result may be low.
[0006]
Here, in the devices described in Patent Documents 1 and 2, the determination result of the fuel property based on the combustion state is trusted and the determination result is reflected in the control specifications. For this reason, even when the reliability of the determination result is low, control parameters corresponding to the determination result are set, that is, control parameters not corresponding to the fuel properties are set, and thereby the combustion state As a result, the exhaust emission may deteriorate, for example.
[0007]
In addition, there is an apparatus for determining the fuel property based on the rotational fluctuation of the internal combustion engine, which prohibits the determination of the fuel property when an external load (such as an air conditioner compressor) is operated (see Patent Document 3). .
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is an internal combustion engine capable of determining the reliability of the determination result of the fuel property in the control device for the internal combustion engine that determines the fuel property. It is to provide a control device.
[0009]
[Means for Solving the Problems]
  The means for achieving the above object and the effects thereof will be described below.
  The invention according to claim 1 is a combustion state of an internal combustion engine.Index value reflecting instability ofA control device for an internal combustion engine, comprising: a fuel property determination unit that determines a fuel property based on the control unit; and a change unit that changes a control specification related to combustion of the internal combustion engine to reflect a determination result of the fuel property determination unit With the change of the control specificationsThe index valueAnd the reliability of the determination result based on the detection result.As its correctnessA reliability determination means for determiningWhen the reliability determination means determines that the reliability is low, the value of the control specifications changed by the changing means is returned to the value before the change.This is the gist.
[0010]
  In the same configuration, the combustion state of the internal combustion engineIndex value reflecting instability ofBased on this, the fuel properties are determined, and based on the determination results, the control parameters are changed to those corresponding to the fuel properties, so that the combustion state of the internal combustion engine is improved. By the way, a combustion state changes also with various factors other than a fuel property. For this reason, in the above configuration, for example, it is determined that the fuel property has changed despite the fact that the fuel property has not changed, and there is a possibility that the control specifications corresponding to the erroneously determined fuel property are changed.
[0011]
  Here, if the reliability of the determination result of the fuel property is high, it is reflected in the control specifications so that the combustion state of the internal combustion engineInstabilityIs in line with its fuel properties, but if its reliability is low, it has a different combustion state.InstabilityWill come to show. That is, according to the reliability of the judgment result, the combustion stateInstabilityWill show different aspects. Therefore, this combustion stateIndex values that reflect instabilityReliability of the above judgment result based on changeAs its correctnessCan be determined. Therefore, in the above configuration, the combustion state accompanying the change in the control specificationsIndex value reflecting instability ofAnd a reliability determination means for determining the reliability of the determination result of the fuel property based on the detection result. Therefore, the reliability of the determination result of the fuel property can be determined.
[0012]
  If the control parameters corresponding to the fuel property determination result are changed and the reliability of the determination result is low, the combustion state may become more unstable than before the change. In view of this, in the above-described configuration, the control means for returning the value of the control specification changed by the changing means to the value before the change when the reliability determining means determines that the reliability is low is provided. . Therefore, the deterioration of the combustion state can be suitably suppressed.
[0013]
  Claim2The invention described in claim1In the control device for an internal combustion engine according to claim 1, the reliability determination unit calculates a frequency at which the index value exceeds a predetermined value in a predetermined period, and the reliability is determined based on a change amount of the frequency according to a change in the control specifications. The gist is to determine the degree.
[0014]
  According to this configuration, the instability of the combustion state of the internal combustion engine can be suitably detected, and the accuracy of the determination can be improved.
  Claim3The invention described in claim 1Or 2In the control device for an internal combustion engine described in (1), the gist is that the index value is rotational fluctuation or combustion pressure of the internal combustion engine.
[0015]
  For example, as the index value, the combustion state of the internal combustion engine can be suitably detected by adopting the rotational fluctuation or in-cylinder pressure of the internal combustion engine..
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment embodying a control device according to the present invention will be described.
FIG. 1 is a schematic diagram showing an internal combustion engine (hereinafter referred to as “engine”) mounted on a vehicle and its peripheral configuration.
[0021]
The engine 2 is provided with a spark plug 14 that ignites the air-fuel mixture in the combustion chamber 10. The intake port 16 connected to the combustion chamber 10 is opened and closed by driving the intake valve 2a. A fuel injection valve 12 that injects fuel toward each intake port 16 is provided in the middle of each intake passage 20 connected to each intake port 16. Each intake passage 20 is connected to one surge tank 22, and a throttle valve 26 whose opening degree is adjusted by a motor 24 is provided in the intake passage 20 upstream of the surge tank 22. The intake air amount GA is adjusted by the opening of the throttle valve 26 (throttle opening TA). The throttle opening degree TA is detected by the throttle opening degree sensor 28 and read into the control device 4. The intake air amount GA is detected by an intake air amount sensor 30 provided on the upstream side of the throttle valve 26 and read into the control device 4.
[0022]
The exhaust port 32 connected to the combustion chamber 10 is opened and closed by driving the exhaust valve 2b. An exhaust purification catalyst 38 such as a three-way catalyst or a NOx occlusion reduction catalyst is disposed in the middle of the exhaust passage 36 connected to the exhaust port 32.
[0023]
Each fuel injection valve 12 is connected to a delivery pipe so that fuel is pumped from the fuel pump through the delivery pipe. The fuel pressure in the delivery pipe or each fuel injection valve 12 is detected by the fuel pressure sensor 40 and read into the control device 4.
[0024]
In addition, instead of the gasoline engine that injects fuel from the fuel injection valve 12 to the intake port 16 as described above, an in-cylinder injection type gasoline engine that directly injects fuel into the combustion chamber 10 may be used.
[0025]
The control device 4 is an engine control circuit that is configured around a digital computer. In addition to the throttle opening sensor 28, the intake air amount sensor 30, and the fuel pressure sensor 40, the control device 4 receives signals from sensors that detect the operating state of the engine 2. That is, signals are also input from an accelerator sensor 48 that detects the depression amount ACCP of the accelerator pedal 46, an engine speed sensor 50 that detects the engine speed NE from the rotation of the crankshaft, and the like. Further, signals are also input from a coolant temperature sensor 54 that detects the engine coolant temperature THW and an air-fuel ratio sensor 56 that detects the air-fuel ratio of the air-fuel mixture from the exhaust components in the exhaust passage 36. In addition to such sensors, various sensors are provided as necessary.
[0026]
The control device 4 executes various arithmetic processes based on the detection contents from the above-described sensors, and controls the fuel injection amount, the fuel injection timing according to the control signal for each drive circuit of the fuel injection valve 12, the spark plug 14 or the motor 24. The fuel ignition timing, the throttle opening, etc. are controlled as appropriate.
[0027]
Now, the fuel for the internal combustion engine includes light fuel with high volatility and heavy fuel with low volatility, and the combustion state of the engine 2 changes depending on the properties of these fuels. Accordingly, in the present embodiment, a fuel property determination process for determining the fuel property based on the combustion state of the engine 2 and a change process for changing the control parameters related to the combustion of the engine 2 to reflect the determination result of the fuel property. I am trying to do it. In this embodiment, the fuel injection amount set according to the engine operating state is a control specification that is changed to reflect the determination result of the fuel property. Ignition timing or the like may be employed. Incidentally, the fuel property determination process constitutes a fuel property determination unit, and the change process constitutes a change unit.
[0028]
By the way, since the combustion state changes depending on various factors other than the fuel property, the fuel property may be erroneously determined depending on the case. In this case, since the fuel injection amount corresponding to the erroneously determined fuel property is set, the combustion state may deteriorate, for example, the exhaust emission may deteriorate.
[0029]
Here, if the reliability of the determination result of the fuel property is high, the combustion state of the engine 2 conforms to the fuel property by reflecting it in the control specifications, while if the reliability is low. A different combustion state is exhibited. That is, the combustion state shows a different aspect according to the reliability of the determination result. Therefore, the reliability of the determination result can be determined based on the change in the combustion state.
[0030]
Therefore, in the control apparatus for an internal combustion engine according to the present embodiment, a reliability determination unit that detects a change in the combustion state accompanying a change in the control specifications and determines the reliability of the determination result of the fuel property based on the detection result. I have to prepare. Furthermore, provided with a restriction means for restricting the operation control of the engine 2 by the changed control parameters changed by the change processing on condition that the reliability determination means determines that the reliability is low. I am doing so.
[0031]
Hereinafter, a description will be given of the control specification switching process including the reliability determination means and the restriction means.
FIG. 2 shows a flowchart of the control specification switching process executed by the control device 4. This process is a process that is repeatedly executed at a crank angle rotation period corresponding to the number of cylinders. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.
[0032]
When this process is started, a combustion level Lfa calculation process is first performed (S100). Details of the combustion level Lfa calculation process are shown in the flowchart of FIG. First, 30 ° CA rotation time T30 (ms) is read (S101). The 30 ° CA rotation time T30 is obtained by measuring the time during which the piston 11 rotates from top dead center to ATDC 30 ° CA in the combustion stroke of each cylinder, and is obtained by the measurement process continuously executed by the control device 4. It has been. This 30 ° CA rotation time T30 reflects the output torque accompanying the combustion of each cylinder, and becomes shorter when the output torque is large, and becomes longer when the output torque is small.
[0033]
Next, as shown in the following equation (1), the absolute value of the difference between the latest 30 ° CA rotation time T30 read this time and the 30 ° CA rotation time T30old in the previous explosion stroke is calculated as the rotation fluctuation dtn (ms). (S102).
[0034]
dtn ← | T30−T30old | (1)
Here, if the combustion state is stable, the output torque accompanying the combustion of each cylinder becomes substantially the same, so the value of the rotational fluctuation dtn becomes small. On the other hand, if the combustion state is deteriorated, the output torque accompanying the combustion of each cylinder will vary, so the value of the rotational fluctuation dtn becomes large. That is, the combustion state is reflected in the rotational fluctuation dtn.
[0035]
Next, the value of the latest 30 ° CA rotation time T30 read this time is set as the 30 ° CA rotation time T30old (S103), and the rotation fluctuation dtn which is an index value reflecting the combustion state is set as the combustion level Lfa. (S104).
[0036]
Thus, the combustion level Lfa calculation process is exited, and it is determined whether or not the calculated combustion level Lfa is equal to or greater than the integration permission determination value Lx (S210 in FIG. 2). Here, the integration permission determination value Lx is a reference value for determining whether or not the combustion level Lfa is a combustion level value that should be integrated with a rotation fluctuation integrated value Sfa, which will be described later, that is, a value for determining whether the combustion level Lfa is within the allowable range of integration. And a value corresponding to the rotational fluctuation dtn when the combustion state deteriorates is set.
[0037]
If Lfa <Lx (NO in S210), the process is temporarily terminated as it is.
On the other hand, if Lfa ≧ Lx (YES in S210), it is determined whether or not the fuel property flag FL indicating the fuel property determination result is “1” (S220). The fuel property flag FL is set to “1” when it is determined that the currently used fuel is heavy fuel, and at this time, control parameters corresponding to the heavy fuel are set. On the other hand, when it is determined that the currently used fuel is light fuel, it is set to “0”, and at this time, the control parameters corresponding to the light fuel are set. In this embodiment, the initial value of the fuel property flag FL is set to “0”. Therefore, in S220, it is determined whether or not it is already determined that the currently used fuel is heavy fuel.
[0038]
When the fuel property flag FL is not set to “1”, that is, when the fuel property flag FL is set to the initial value “0” (NO in S220), the combustion state deteriorates, that is, the combustion A combustion failure frequency FA indicating the frequency of deterioration of the level Lfa is calculated (S230). Here, the number of times the combustion level Lfa is equal to or higher than the frequency calculation combustion level Ly in the past N ignition times is counted as the combustion failure frequency FA. That is, the past N combustion levels Lfa are stored, and the number of times Lfa ≧ Ly is obtained. The frequency calculation combustion level Ly is a reference value for determining the deterioration of the combustion state, and the same value as the integration permission determination value Lx may be used, Ly <Lx may be used, or Ly> Lx may be used. The combustion failure frequency FA calculated here indicates instability of the combustion state when the fuel property flag FL is set to “0”, that is, when the control parameters corresponding to the light fuel are set. Calculated as a value.
[0039]
Next, the rotational fluctuation integrated value Sfa is integrated by the following equation (2) (S240). The rotation fluctuation integrated value Sfa is set to Sfa = “0” by the initial setting when the ignition is turned on.
[0040]
Sfa ← Sfa + Lfa (2)
Next, it is determined whether or not the rotation fluctuation integrated value Sfa is greater than or equal to the heavy fuel determination reference value Sx (S250). This heavy fuel determination criterion Sx is a value set based on the rotation fluctuation when the heavy fuel is used in the state where the control parameters corresponding to the light fuel are set, and the rotation fluctuation integrated value If Sfa is greater than or equal to the heavy fuel determination reference value Sx, it is determined that heavy fuel is currently being used.
[0041]
If Sfa <Sx (NO in S250), it is determined that the fuel is not yet heavy fuel, and this processing is temporarily terminated as it is, and the operation control based on the light fuel control parameters is maintained.
[0042]
On the other hand, when it is determined “NO” in S250 each time this control specification switching process is repeatedly executed, the rotation fluctuation integrated value Sfa in S240 increases. If Sfa ≧ Sx (YES in S250), it is determined that the currently used fuel is heavy fuel. Therefore, the fuel property flag FL is set to “1” (S260), the operation is switched to the operation control using the heavy fuel control parameters (S270), and this process is temporarily ended. Thereafter, the operation control is performed in a state in which the control parameters for light fuel are changed to the control parameters for heavy fuel. That is, the fuel injection amount corresponding to the heavy fuel is set.
[0043]
When it is determined “YES” in S220, that is, when the fuel property flag FL is set to “1”, the combustion state in the state where the fuel property flag FL is set to “1”. Is calculated, that is, the combustion failure frequency FB indicating the frequency of deterioration of the combustion level Lfa (S280). The combustion failure frequency FB calculated here is the instability of the combustion state when the fuel property flag FL is set to “1”, that is, when the control parameters corresponding to the heavy fuel are set. It is calculated as the value shown.
[0044]
Next, the amount of change in the combustion failure frequency FB showing the instability of the combustion state after the change of the control specification is made based on the combustion failure frequency FA showing the instability of the combustion state before the change of the control specification. It is determined whether or not exceeds a predetermined value. More specifically, as shown in the following equation (3), it is determined whether or not a value obtained by subtracting the combustion failure frequency FA from the combustion failure frequency FB exceeds a determination value A set as a threshold value. In the present embodiment, the determination value A is set to “0”. Therefore, in this determination, it is determined whether or not the combustion failure frequency FB is substantially equal to or higher than the combustion failure frequency FA (S290). Whether or not the combustion state after the change of the control specifications is more stable by the processing of S290, in other words, whether or not the combustion state of the engine 2 is in accordance with the determined fuel property. Can be judged.
[0045]
Combustion failure frequency FB−Combustion failure frequency FA ≧ determination value A (3)
Incidentally, when the determination value A is set to a value other than “0” when comparing the combustion failure frequency FB and the combustion failure frequency FA, hysteresis can be provided for the determination. Therefore, for example, even when accidental deterioration of the combustion state is counted in calculating the combustion failure frequencies FA and FB, the influence on the determination of the combustion state based on the above equation (3) can be suppressed. Note that the amount of change in the combustion failure frequency FB with respect to the combustion failure frequency FA may be obtained as a ratio of the other to one instead of the difference between the two.
[0046]
If the combustion failure frequency FB is less than the combustion failure frequency FA (NO in S290), the combustion condition is more stable by switching the control specifications from the light fuel specifications to the heavy fuel specifications. Therefore, it can be considered that there is no error in the determination result of the fuel property, that is, the reliability of the determination result is high, and this process is temporarily terminated.
[0047]
On the other hand, if the combustion failure frequency FB is equal to or higher than the combustion failure frequency FA (YES in S290), it is determined that the fuel used is heavy fuel, so that the control specifications are for light fuel. It can be said that the combustion state has become more unstable or has not changed in spite of being switched to the control parameters for heavy fuel. In other words, the fuel property judgment result is incorrect because the combustion state has become more unstable or has not changed even though the operation control is performed with the control parameters reflecting the fuel property judgment result. Therefore, it can be considered that the reliability of the determination result is low. Therefore, in order to prohibit the operation control based on the currently set heavy fuel control parameters, the fuel property flag FL is reset to “0” (S300), and the currently set heavy fuel control is set. The value of the specification is returned to the value for light fuel (S310). And this process is once complete | finished. Thereafter, operation control using the light fuel control parameters is performed. That is, the fuel injection amount corresponding to the light fuel is set.
[0048]
Thus, in the above processing, the combustion failure frequency FA obtained from the combustion level Lfa when the control parameters corresponding to the light fuel are set and the combustion when the control parameters corresponding to the heavy fuel are set. Based on the combustion failure frequency FB obtained from the level Lfa, the reliability of the fuel property determination result is determined. If an erroneous determination of the fuel property is found by this determination, the value of the control specification changed based on the determination result of the fuel property is returned to the value before the change. Therefore, operation control by control specifications that do not correspond to actual fuel properties is suppressed.
[0049]
As described above, according to the control apparatus for an internal combustion engine according to the present embodiment, the following effects can be obtained.
(1) The change in the combustion state accompanying the change in the control specifications is detected, and the reliability of the determination result of the fuel property is determined based on the detection result. More specifically, the rotational fluctuation dtn (combustion level Lfa) reflecting the combustion state is detected, and the rotational fluctuation dtn (combustion associated with the change from the light fuel control specifications to the heavy fuel control specifications). The reliability is determined based on the amount of change in level Lfa). Therefore, the reliability of the determination result of the fuel property can be determined.
[0050]
(2) When determining the reliability based on the amount of change in the rotational fluctuation dtn (combustion level Lfa), the instability of the combustion state based on the combustion level Lfa before and after the change of the control specifications. The combustion failure frequencies FA and FB indicating the above are respectively calculated. And when the variation | change_quantity of the combustion failure frequency FB with respect to the combustion failure frequency FA is more than the determination value A, it is determined that the said reliability is low and the determination result of a fuel property was an error. Therefore, instability of the combustion state of the engine 2 can be suitably detected, and the accuracy of the determination can be improved.
[0051]
(3) The engine according to the changed control specifications changed based on the fuel property determination result on condition that the reliability is low, that is, it is determined that the fuel property determination result is incorrect. The operation control of 2 is limited, more specifically, it is prohibited. For this reason, since operation control based on control specifications that may not correspond to the actual fuel properties is prohibited, deterioration of the combustion state and the like can be suppressed. Further, when this prohibition is performed, the value of the control specification changed based on the determination result of the fuel property is switched to another value different from this value. Therefore, it is possible to prohibit the operation control based on the changed control specifications and to continue the operation of the engine 2.
[0052]
(4) When the control parameters corresponding to the determination result of the fuel property are changed and the reliability of the determination result is low, the combustion state may be deteriorated as compared to before the change of the control parameters. is there. Therefore, at the time of switching the control specifications, the value of the changed control specifications changed based on the fuel property determination result is returned to the value before the change. Therefore, the deterioration of the combustion state can be suitably suppressed.
[0053]
(5) The integration to the rotation fluctuation integrated value Sfa does not target all the combustion levels Lfa, but the combustion level Lfa within the integration allowable range, that is, the integration permission determination value Lx or more in this case. As a result, the rotational fluctuation integrated value Sfa that more accurately reflects the combustion state to be determined can be obtained, and the fuel property can be determined with higher accuracy.
[0054]
In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, it is determined whether there is an error in the fuel property determination result based on whether the amount of change in the combustion failure frequency FB with respect to the combustion failure frequency FA exceeds a threshold value. In addition, it may be determined that the greater the amount of change in the combustion failure frequency FB with respect to the combustion failure frequency FA, the lower the reliability of the fuel property determination result. That is, the degree of reliability may be obtained based on the magnitude of the change amount.
[0055]
In the embodiment described above, when the amount of change in the combustion failure frequency FB with respect to the combustion failure frequency FA exceeds the determination value A, it is determined that the fuel property determination is incorrect. In addition to this, when the amount of change in the combustion level Lfa after the change in the control specification with respect to the combustion level Lfa before the change in the control specification exceeds a predetermined value, it is determined that the determination of the fuel property is incorrect. Good. Incidentally, as the amount of change at this time, the amount of change of the combustion level Lfa itself after the change with respect to the combustion level Lfa itself before the change or the integrated value of the combustion level Lfa after the change with respect to the integrated value of the combustion level Lfa before the change May be used.
[0056]
In the above embodiment, the rotational fluctuation dtn is used as an index value that reflects the combustion state, and the rotational fluctuation dtn is used as the combustion level Lfa. However, other index values other than the rotational fluctuation dtn may be used as this index value. Good. For example, the level of combustion pressure indicating the pressure in the combustion chamber 10 during combustion, the level of combustion light generated in the combustion chamber 10, or the level of ions generated in combustion in the combustion chamber 10 is used as the index value. Also good.
[0057]
In the above embodiment, the combustion failure frequency FA and the combustion failure frequency FB are the frequencies at which the combustion level Lfa ≧ Ly in the past N ignition times. In addition to this, the number of ignitions from the previous Lfa ≧ Ly to the time when Lfa ≧ Ly this time is counted, and the combustion failure frequency FA and the combustion failure frequency FB are set so as to increase as the number of ignitions decreases. May be calculated.
[0058]
In the above embodiment, the determination of the combustion level Lfa to be integrated based on the integration permission determination value Lx may not be performed, and all the combustion levels Lfa may be targeted for integration.
In the above embodiment, the reliability of the fuel property determination result is low, that is, based on the fuel property determination result as the restriction mode when it is determined that the fuel property determination result is incorrect. The operation control of the engine 2 by the changed control specifications after being changed is prohibited. In addition to the above, the above restriction can be performed in such a manner that the degree of change of the control specifications changed based on the determination result of the fuel property is reduced.
[0059]
In the above embodiment, when it is determined that there is an error in the fuel property determination result, the control parameters changed based on the fuel property determination result are changed to the control parameters before the change (control parameters for light fuel). However, it may be switched to another control specification.
[0060]
In the above embodiment, the light fuel control parameters are set to the initial values, but the same effect can be obtained even when the heavy fuel control parameters are set to the initial values.
-In the said embodiment, the control specifications for light fuel were made into the initial value. In addition to this, for example, the control parameters set based on the fuel properties between the properties of light fuel and heavy fuel are set as initial values, and the subsequent control parameters are determined based on the determination result of the fuel properties. The present invention can be similarly applied as long as the fuel property is determined and the determination result is reflected in the control specifications such as those to be set.
[0061]
The switching of the control parameters in the above embodiment may be executed not only for the fuel injection amount but also for the fuel injection timing and the fuel ignition timing at the same time.
-Although the example of the gasoline engine was given in the said embodiment, this invention is applicable also to a diesel engine.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a schematic configuration of an internal combustion engine to which an embodiment of the present invention is applied.
FIG. 2 is a flowchart showing a procedure of control specification switching processing in the embodiment.
FIG. 3 is a flowchart showing a procedure of combustion level calculation processing in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Engine, 2a ... Intake valve, 2b ... Exhaust valve, 4 ... Control apparatus, 10 ... Combustion chamber, 11 ... Piston, 12 ... Fuel injection valve, 14 ... Spark plug, 16 ... Intake port, 20 ... Intake passage, 22 DESCRIPTION OF SYMBOLS ... Surge tank, 24 ... Motor, 26 ... Throttle valve, 28 ... Throttle opening sensor, 30 ... Intake air amount sensor, 32 ... Exhaust port, 36 ... Exhaust passage, 38 ... Exhaust purification catalyst, 40 ... Fuel pressure sensor, 46 Accelerator pedal 48 Accelerator sensor 50 Engine speed sensor 54 Cooling water temperature sensor 56 Air-fuel ratio sensor

Claims (3)

Fuel property determination means for determining the fuel property based on an index value reflecting instability of the combustion state of the internal combustion engine, and control parameters relating to combustion of the internal combustion engine to reflect the determination result of the fuel property determination means An internal combustion engine control device having a changing means for changing
A reliability determination unit that detects a change in the index value due to the change in the control specifications and determines the correctness as the reliability of the determination result based on the detection result, the reliability determination unit includes the reliability determination unit A control device for an internal combustion engine , wherein when it is determined that the degree is low, the value of the control data changed by the changing means is returned to the value before the change . The said reliability determination means calculates the frequency that the said index value exceeds a predetermined value in a predetermined period, and determines the said reliability based on the variation | change_quantity of this frequency accompanying the change of the said control specification . Control device for internal combustion engine. The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the index value is a rotational fluctuation or a combustion pressure of the internal combustion engine.

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