JP2007002814A - Misfire detection device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a misfire detection device having improved detection (determination) accuracy compared to a conventional misfire detection device.
A misfire detection apparatus for an internal combustion engine according to the present invention includes a crank angle detection means for detecting a crank angle of the internal combustion engine, a rotational energy amount calculation means, and the rotational energy calculated by the rotational energy amount calculation means. A misfire determination means for determining misfire of the internal combustion engine by comparing a variation amount of the amount with a misfire determination value for determining misfire, and the misfire determination value is a function of an engine speed and an intake air amount And a storage device previously stored in the map as a value, wherein the rotational energy amount is calculated from a rotational moment of inertia calculated based on the detected crank angle.
[Selection] Figure 2

Description

  The present invention relates to a misfire detection apparatus for an internal combustion engine that detects misfire occurring in the internal combustion engine.

  Conventionally, as a prior art document related to an engine misfire detection device, one disclosed in Patent Document 1 or Patent Document 2 is known. Among these, Patent Document 1 discloses a technique for calculating a variation amount of the engine rotation speed and comparing the variation amount with a misfire determination value to determine misfire. Patent Document 2 discloses a technique for determining misfire based on engine rotational acceleration.

JP 2004-218605 A JP-A-6-229310

  However, the engine rotational speed and the engine rotational acceleration are actually influenced by the inertial force that changes with each crank angle due to the reciprocating mass of the piston, connecting rod, etc. In Patent Document 1 and Patent Document 2, The inertial force is handled as a constant value. As for the engine mounted on the vehicle, the torsional vibration of the drive shaft affects the engine rotation speed and the like, but Patent Document 1 or Patent Document 2 does not consider this effect at all. For this reason, the accuracy of misfire determination was not sufficient.

  An object of the present invention is to provide a misfire detection (determination) device with improved detection (determination) accuracy compared to a conventional misfire detection device.

According to the invention of claim 1,
Crank angle detection means for detecting the crank angle of the internal combustion engine;
Rotational energy amount calculating means;
Misfire determination means for determining misfire of the internal combustion engine by comparing a fluctuation amount of the rotational energy amount calculated by the rotational energy amount calculation means with a misfire determination value for determining misfire;
A storage device in which the misfire determination value is stored in advance in a map as a function value of the engine speed and the intake air amount;
The rotational energy amount is calculated from a rotational moment of inertia calculated based on the detected crank angle, and a misfire detection device for an internal combustion engine is provided.

  As described above, according to the misfire detection device for an internal combustion engine according to the first aspect, the rotational energy amount calculated from the rotational moment of inertia based on the detected crank angle is employed as the misfire determination value. For this reason, detection (determination) accuracy can be improved compared with the conventional misfire determination apparatus which handles the rotational inertia moment as a fixed value.

According to invention of Claim 2,
The crank angle reference position detecting means, which is a part of the crank angle detecting means, is arranged at two locations, near the front end of the crankshaft and near the rear end in the same phase as the front end. The rotational energy amount is corrected based on a relative angle difference between the crank angle at the front end and the crank angle at the rear end calculated from two detection values at the same time by a reference position detection unit. An internal combustion engine misfire detection apparatus according to Item 1, is provided.
As described above, according to the misfire detection apparatus for an internal combustion engine according to claim 2, the fluctuation amount of the crank angular velocity caused by the torsional vibration of the crankshaft accompanying the engine rotation is corrected. As a result, detection (determination) accuracy can be improved.

According to invention of Claim 3,
In an internal combustion engine mounted on a vehicle, the rotational speed of a turbine and / or wheel rotational speed incorporated in a torque converter connecting the internal combustion engine and a transmission and / or driving of the auxiliary equipment when the auxiliary equipment driving is turned on The misfire detection device for an internal combustion engine according to claim 1 or 2, wherein the rotational energy amount is corrected based on a load.
As described above, according to the misfire detection device for an internal combustion engine according to claim 3, in the internal combustion engine mounted on the vehicle, the variation amount of the crank angular velocity due to various disturbance factors is corrected, so that the calculated rotational energy amount This improves the accuracy of detection, and in turn improves the detection (determination) accuracy.

According to invention of Claim 4,
In an internal combustion engine mounted on a vehicle, calculating a fluctuation amount of the rotational energy amount based on the rotational energy amount after numerically processing the rotational energy amount and performing frequency analysis to remove a predetermined low-frequency numerical value. The misfire detection device for an internal combustion engine according to any one of claims 1 to 3, characterized in that:
Thus, according to the misfire detection apparatus for an internal combustion engine according to claim 4, the calculated rotational energy amount is removed in order to remove the rotational energy amount fluctuation component caused by the low-frequency torsional vibration generated in the wheel drive shaft system. This improves the accuracy of detection, and in turn improves the detection (determination) accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the misfire detection apparatus which improved detection accuracy rather than the conventional misfire detection apparatus can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram illustrating an engine to which a misfire detection apparatus according to a first embodiment of the present invention is applied and peripheral devices thereof.

  In FIG. 1, reference numeral 10 denotes an engine composed of four-cycle six cylinders (first cylinder to sixth cylinder), and reference numeral 11 denotes an intake passage for supplying intake air introduced from an air cleaner 12 to the engine 10 side. Reference numeral 13 denotes an intake air amount sensor such as an air flow meter that detects an intake air amount GN introduced into the intake passage 11.

  A rotational speed sensor 21 is provided on the crankshaft 16 of the engine 10 and outputs a signal at every predetermined crank angle to obtain an engine rotational speed NE. 23 is usually built in the distributor 22 and discriminates a specific cylinder. For example, a reference position sensor that detects a reference position G for each compression TDC (Top Dead Center) at which the piston 17 of the first cylinder rises most. Then, the crank angle is calculated based on the two detected values by the reference position sensor 23 and the rotational speed sensor 21. In this document, the reference position sensor 23 and the rotation speed sensor 21 are referred to as crank angle detection means. A water temperature sensor 24 is disposed in the cooling water passage of the engine 10 and detects the cooling water temperature THW.

  Reference numeral 30 denotes an intake air amount GN from the intake air amount sensor 13, an engine rotational speed NE from the rotational speed sensor 21, a reference position G from the reference position sensor 23, a cooling water temperature THW from the water temperature sensor 24, and other various sensor signals. An ECU (Electronic Control Unit) that inputs and calculates optimum control amounts in the fuel system and the ignition system and outputs control signals for accurately controlling the injector (fuel injection valve) 26, the igniter 27, etc. It is.

  The ECU 30 includes a CPU 31 as a central processing unit that executes various known arithmetic processes, a storage device ROM 32 that stores control programs and control maps, a storage device RAM 33 that stores various data, a B / U (backup) RAM 34, an input It is configured as a logical operation circuit comprising an output circuit 35 and a bus line 36 connecting them. Reference numeral 29 denotes a warning lamp for notifying the driver or the like of the occurrence of misfire when the ECU 30 determines that misfire has occurred.

  Next, a description will be given with reference to FIG. 3 based on the flowchart of FIG. 2 showing the misfire presence / absence determination procedure in the CPU 31 in the ECU 30 used in the engine misfire detection apparatus according to the embodiment of the present invention. Here, FIG. 3 is a map for calculating the misfire determination value REF for determining the presence or absence of misfire during operation of the engine 10 using the intake air amount GN and the engine rotation speed as parameters in FIG. This misfire determination routine is repeatedly executed by the CPU 31 with an interruption every predetermined crank angle, for example, 30 ° CA (Crank Angle).

In FIG. 2, first, in step S101, the crankshaft 16 is required to rotate 30 ° CA from the crank angle θ _{1 of} the current interrupt time and the deviation between the previous interrupt time and the current interrupt time. The current time T30 _i is calculated. Next, the process proceeds to step S102, and it is determined whether the current interrupt timing is the compression TDC in any of the first to sixth cylinders. If the determination condition in step S102 is not satisfied, that is, if the current interrupt timing is not compression TDC, this routine is terminated without doing anything.

On the other hand, when the determination condition of step S102 is satisfied, that is, when the current interrupt timing is the compression TDC in any of the first to sixth cylinders, the process proceeds to step S103 and is calculated in step S101. Based on the reciprocal of the time T30 _i required for the crankshaft 16 of the engine 10 to rotate by 30 ° CA, the current angular velocity ω _i and the engine rotational speed NE _i are calculated. At the next step S104, the current rotational energy amount Ke _i is calculated by the following equation (1).

Ke _i = 0.5 × J (θ _i ) × ω _i ² (1)
Here, Ke _i: rotational energy amount (in compression TDC),
θ _i : crank angle (in compression TDC),
J (θ _i ): Rotational moment of inertia (at θ _i ),
ω _i : Crank angular velocity (from 30 ° CA before compression TDC to compression TDC)

  Next, the process proceeds to step S105, where the intake air amount GN is read from the intake air amount sensor 13. Next, the process proceeds to step S106, and misfire for determining the presence or absence of misfire based on the map shown in FIG. 3 using the intake air amount GN read in step S105 and the engine rotational speed NE calculated in step S103 as parameters. A determination value REF is calculated. Note that the misfire determination value REF for the intermediate value of each parameter in FIG. 3 is obtained by interpolation calculation.

Next, the process proceeds to step S107, where the interrupt time is 90 ° CA after the interrupt time of 60 ° CA (that is, the next time) from the current interrupt time (that is, this time is called “new this time”) A new current time T30 _{i + 1} required for the crankshaft 16 to rotate 30 ° CA is calculated from the deviation from the time. The new crank angle θ _{i + 1} is automatically calculated. Next, the process proceeds to step S108, where the new current angular velocity ω _{i + 1} is calculated based on the reciprocal of the time T30 _{i + 1} calculated in step S107. The new angular velocity ω _{i + 1} should be higher than the current angular velocity ω _i if combustion is normally performed in the vicinity of the immediately preceding compression TDC (no misfire).

Next, proceeding to step S109, the new rotational energy amount Ke _{i + 1} (at 90 ° CA after compression TDC) is calculated by the following equation (1) using the following parameters.
That is, the parameters are θ _{i + 1} : crank angle (at 90 ° after compression TDC), J (θ _{i + 1} ): rotational moment of inertia (at θ _{i + 1} ), ω _{i + 1} : crank angular velocity (compression TDC) After 60 ° CA to 90 ° after compression TDC).

At the next step S110, the current rotational energy variation ΔKe _i, and the current rotation energy amount Ke _i calculated in the new current rotational energy amount Ke _{i + 1} and the step S104 which is calculated in step S109 Is calculated by the following equation (2).
_{ΔKe i = Ke i + 1 -} Ke i ··· (2)

At the next step S111, the current rotational energy variation DerutaKe _i calculated in step S110 is either turned misfire judgment value or more REF calculated in step S106 is determined. Judgment condition is satisfied in step S111, i.e., proceeds to step S112 when the current rotational energy variation DerutaKe _i is smaller than the misfire judgment value REF, the misfire determination flag XMF is set to "1" indicating that there is a misfire. On the other hand, not satisfied the determination condition in step S111, i.e., it proceeds to step S113 when the current rotational energy variation DerutaKe _i is greater than the misfire judgment value REF, the misfire determination flag XMF represents no misfire "0" Set. In this way, this routine ends.

  In the map of FIG. 3 used in the misfire presence / absence determination routine, the misfire determination value REF is calculated using the intake air amount GN and the engine rotational speed NE as parameters.

  Next, a description will be given based on a flowchart of FIG. 4 showing an abnormality diagnosis processing procedure in the CPU 31 in the ECU 30 used in the engine misfire detection apparatus according to the embodiment of the present invention. This abnormality diagnosis routine is repeatedly executed by the CPU 31 every predetermined time.

  In FIG. 4, in step S201, the states of various abnormality determination flags including the misfire determination flag XMF by the misfire presence / absence determination routine are read. Next, the process proceeds to step S202, and occurrence of an abnormality is determined based on the states of various abnormality determination flags read in step S201. If the determination condition in step S202 is not satisfied, that is, if the states of the various abnormality determination flags are all “0”, it is determined that there is no abnormality, and this routine is terminated.

  On the other hand, when the determination condition in step S202 is satisfied, that is, any one of the states of various abnormality determination flags is “1”, the process proceeds to step S203. In step S203, for example, when the above-described misfire determination flag XMF is set to “1” as the state of various abnormality determination flags, the protection of the catalyst (not shown) and the concentration of HC (hydrocarbon) in the exhaust gas are performed. In order to prevent an increase, a well-known fail-safe system that detects abnormalities, such as stopping fuel supply to cylinders that have been determined to have misfired, or lighting a warning 29 to notify the driver of misfires, etc. Processing is executed, and this routine is terminated.

Thus, the engine misfire detection apparatus of the present embodiment has an angular velocity ω _i that is the reciprocal of the time required for the crankshaft 16 of the engine 10 detected by the rotational speed sensor 21 to rotate 30 ° CA as a predetermined period. misfire for determining the rotational energy fluctuation amount calculating means which is achieved by ECU30 to calculate the rotational energy variation ΔKe _i, a misfire and the rotational energy variation DerutaKe _i calculated by the rotational energy change amount calculation means on the basis of A misfire detection means that is achieved by the ECU 30 that detects the misfire of the engine 10 by comparing the judgment value REF, and the misfire judgment value REF is previously mapped as a function value of the engine speed and the intake air amount Is stored.

That is, the misfire determination value REF engine speed, stored in advance in the mapped memory device ROM32 the intake air amount as parameters are (see FIG. 3), the rotational energy variation DerutaKe _i and a misfire determination value REF The presence or absence of misfire in the engine 10 is determined by the comparison.

  In the engine misfire detection apparatus of the present embodiment, the rotational energy of the current combustion stroke and the rotational energy of the previous combustion stroke are in the same phase in each combustion stroke.

  In the above embodiment, the engine 10 is assumed to be a 4-cycle 6-cylinder (first cylinder to sixth cylinder). However, the present invention is not limited to this, and is not necessary. In calculating the rotational energy fluctuation amount, the rotational energy in the same phase in the successive combustion strokes may be used.

Next, a second embodiment of the present invention will be described.
As is well known, the crankshaft of a multi-cylinder engine generates torsional vibration. This torsional vibration affects the crank angular velocity, causing an error in the calculation accuracy of rotational energy. Therefore, the relative torsional angle difference between the front end and the rear end of the crankshaft due to torsional vibration is measured, and the rotational energy amount is corrected based on the torsional relative angle difference.

  The crank angle detection means refers to the reference position sensor 23 and the rotation speed sensor 21. The two reference position sensors 23 (crank angle reference position detecting means) are arranged at two locations, the vicinity of the front end of the crankshaft and the vicinity of the rear end in the same phase as the vicinity of the front end. The rotational energy amount is corrected based on the relative angle difference between the crank angle at the front end and the crank angle at the rear end calculated from two detection values at the same time. The accuracy of misfire detection can be secured by the correction calculation process.

Next, a third embodiment of the present invention will be described.
In an engine mounted on a vehicle, a sudden load is applied to the engine when traveling on a rough road or during a shift change, and there is a possibility that the misfire determination means may erroneously determine misfire. For this reason, the rotational speed of a turbine (not shown) built in a torque converter (see FIG. 5) connecting the engine and the transmission is measured by a sensor, and the rotational energy amount is corrected by the turbine rotational speed. The turbine rotation speed is a rotation speed on the transmission side. For this reason, when the rotational speed on the transmission side (propeller shaft side) decreases during rough road traveling or shift change, the amount of decrease can be directly detected. The accuracy of misfire detection can be ensured by the correction calculation process.

Next, a fourth embodiment of the present invention will be described.
In an engine mounted on a vehicle, the crank angular velocity is affected by the torsional vibration of the vehicle drive system, causing an error in the calculation accuracy of rotational energy. As shown in FIG. 5, the vehicle drive system mainly refers to a propeller shaft and a drive shaft. The frequency of torsional vibration of the vehicle drive system is several hertz to 20 hertz and is a low frequency. This torsional vibration can be estimated from the wheel rotation speed and the engine rotation speed.
That is, by measuring the wheel rotational speed, it is possible to perform an arithmetic process for correcting the influence of the torsional vibration on the rotational energy amount. The accuracy of misfire detection can be ensured by the correction calculation process. In particular, at the time of lockup control of the torque converter, the correction according to the third embodiment cannot be performed, so the fourth embodiment is useful.

  Also, instead of measuring the wheel rotational speed, the rotational energy amount (for example, the rotational energy amount of the last n compression TDCs) is numerically processed and subjected to frequency analysis to obtain a predetermined low frequency (several hertz to 20 hertz). It is also possible to perform arithmetic processing for calculating the amount of fluctuation of the rotational energy amount based on the current rotational energy amount and the new rotational energy amount after the above numerical value is removed.

Next, a fifth embodiment of the present invention will be described.
In an engine mounted on a vehicle, when driving of an auxiliary machine such as an air conditioner or a power steering is turned on, a sudden load is applied to the engine, and the misfire determination means may erroneously determine misfire. Therefore, the rotational energy amount is corrected based on the driving load of the auxiliary machine when the auxiliary machine drive is turned on. The accuracy of misfire detection can be ensured by the correction calculation process.

1 is a schematic configuration diagram showing an engine to which a misfire detection device according to an embodiment of the present invention is applied and peripheral devices thereof. It is a flowchart which shows the process sequence of misfire presence determination in CPU in ECU used with the misfire detection apparatus concerning embodiment of this invention. 6 is a map for calculating a misfire determination value using an intake air amount and an engine rotation speed as parameters. It is a flowchart which shows the process sequence of the abnormality diagnosis in CPU in ECU which is a part of misfire detection apparatus concerning embodiment of this invention. It is a schematic diagram showing the engine and drive shaft system which were mounted in the vehicle.

Explanation of symbols

10 Engine 16 Crankshaft 21 Rotational Speed Sensor 30 ECU (Electronic Control Unit)
32 ROM
100 vehicles

Claims (4)

Crank angle detection means for detecting the crank angle of the internal combustion engine;
Rotational energy amount calculating means;
Misfire determination means for determining misfire of the internal combustion engine by comparing a fluctuation amount of the rotational energy amount calculated by the rotational energy amount calculation means with a misfire determination value for determining misfire;
A storage device in which the misfire determination value is stored in advance in a map as a function value of the engine rotation speed and the intake air amount;
The misfire detection device for an internal combustion engine, wherein the rotational energy amount is calculated from a rotational moment of inertia calculated based on the detected crank angle.   The crank angle reference position detecting means, which is a part of the crank angle detecting means, is arranged at two locations, near the front end of the crankshaft and near the rear end in the same phase as the front end. The rotational energy amount is corrected based on a relative angle difference between the crank angle at the front end and the crank angle at the rear end calculated from two detection values at the same time by a reference position detection unit. Item 6. A misfire detection apparatus for an internal combustion engine according to Item 1.   In an internal combustion engine mounted on a vehicle, the rotational speed of a turbine and / or wheel rotational speed incorporated in a torque converter connecting the internal combustion engine and a transmission and / or driving of the auxiliary equipment when the auxiliary equipment driving is turned on The misfire detection device for an internal combustion engine according to claim 1 or 2, wherein the rotational energy amount is corrected based on a load.   In an internal combustion engine mounted on a vehicle, calculating a fluctuation amount of the rotational energy amount based on the rotational energy amount after numerically processing the rotational energy amount and performing frequency analysis to remove a predetermined low-frequency numerical value. The misfire detection apparatus for an internal combustion engine according to any one of claims 1 to 3, characterized by:

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