JP2009091920A - Fuel-supply abnormality determination method and device of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in which, when abnormality of fuel supply for any of cylinders of a multi-cylinder internal combustion engine, the cylinder being set with a plurality of fuel-supply patterns, is to be determined, the abnormality cannot be determined correctly in patterns other than a specific fuel-supply pattern. <P>SOLUTION: A fuel-supply abnormality determination device includes a fuel-injection amount setting portion 18 for abnormality determination for supplying fuel with a fuel-supply pattern for abnormality determination to arbitrary one cylinder, a crankshaft angular acceleration calculating portion 45 for calculating an angular acceleration of a crankshaft in association with the arbitrary one cylinder based on detection signals from a crank angle sensor 43, a correlation rate calculating portion 46 for calculating a correlation between the fuel-supply amount set for the arbitrary one cylinder and the calculated angular acceleration of the crankshaft, and a fuel-supply abnormality determination portion 47 for comparing the correlation calculated by the correlation rate calculating portion 46 and a predetermined reference correlation and determining the fuel supply abnormality for the arbitrary one cylinder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for determining a fuel supply abnormality related to an arbitrary cylinder in a multi-cylinder internal combustion engine in which a plurality of fuel supply patterns are set according to a driving state of a vehicle.

  In a multi-cylinder internal combustion engine, if the injection hole of a fuel injection valve for supplying fuel to an individual cylinder is clogged or fails for some reason, the amount of fuel supplied to the corresponding cylinder is insufficient. Or the fuel will not be supplied. Therefore, it is desirable to grasp the operation state of an arbitrary single cylinder in such a multi-cylinder internal combustion engine and take some measures in order to maintain a desirable operation state of the multi-cylinder internal combustion engine.

  In Patent Document 1, the angular acceleration of a crankshaft corresponding to a predetermined cylinder is calculated and compared with an average value. When the deviation exceeds a threshold value, it is determined that there is an abnormality in combustion in the predetermined cylinder. Is disclosed.

JP-A-8-28339

  The crankshaft angular acceleration is also affected by the crankshaft driving torque. Particularly in a compression ignition type multi-cylinder internal combustion engine having a plurality of fuel injection modes, the crankshaft angular acceleration is associated with each cylinder. It is difficult to detect accurately. Therefore, when the technique of Patent Document 1 is applied to a compression ignition type multi-cylinder internal combustion engine having a plurality of fuel injection modes, the angular acceleration of the crankshaft may not be calculated with high accuracy by the fuel injection mode. Even if judgment of combustion abnormality is performed, it is not reliable.

  An example of a plurality of fuel injection modes set for the multi-cylinder internal combustion engine is shown in Table 1 below.

  This is generally set in a diesel engine or the like, and when the fuel injection amount is the same, the output torque tends to decrease in the order of single, first to fifth multi. The main injection in Table 1 means that fuel is injected at and near the compression top dead center (TDC), and the pre-injection is injected during the compression stroke before this main injection. It is pilot injection that is injected immediately before. Pilot injection and pre-injection are particularly effective for suppressing combustion noise and vibration during low load and low rotation such as idling. In addition, after / post injection is injected in the expansion stroke after the main injection, and these are selected at the time of cold start of the engine where it is necessary to increase the exhaust temperature and promote the activation of the catalyst. Is done.

  Among these injection modes, the single injection mode in which the output torque is maximum has a feature that the angular acceleration of the crankshaft can be detected with the highest accuracy. However, as described above, in the driving state of the vehicle, there are not many opportunities for the single injection mode to be selected, and if the determination of abnormality in fuel supply is made only in the single injection mode, the determination opportunity There is a concern that there will be considerably less.

  An object of the present invention is a method capable of accurately determining an abnormality in the supply of fuel related to an arbitrary cylinder in a multi-cylinder internal combustion engine in which a plurality of fuel supply patterns are set according to the driving state of the vehicle while suppressing adverse effects on the vehicle. And providing an apparatus.

  A first aspect of the present invention is a method for determining a fuel supply abnormality related to an arbitrary cylinder in a multi-cylinder internal combustion engine in which a plurality of fuel supply patterns are set in accordance with an operating state of the vehicle. Supplying fuel with an abnormality determination fuel supply pattern, calculating the angular acceleration of the crankshaft of the internal combustion engine in association with the arbitrary cylinder, and calculating the angular acceleration of the crankshaft And a step of obtaining a correlation between the fuel supply amount for the one arbitrary cylinder, a comparison between the obtained correlation and a preset correlation, and determining whether or not there is a fuel supply abnormality for any one cylinder. And a step of determining.

  In the present invention, regardless of the fuel supply pattern set according to the driving state of the vehicle, fuel is supplied to an arbitrary cylinder in a fuel supply pattern for abnormality determination, and the crankshaft of the internal combustion engine is The angular acceleration is calculated in association with an arbitrary cylinder. Then, a correlation between the calculated angular acceleration of the crankshaft and the fuel supply amount for an arbitrary cylinder is obtained, and the obtained correlation is compared with a preset correlation. When the obtained correlation is significantly different from the preset correlation, it is determined that there is an abnormality in the fuel supply to any one cylinder.

  When the fuel supply state to each cylinder is normal when the vehicle is running at a constant speed, the relationship between the crankshaft phase and the crankshaft angular velocity is as shown by the solid line in FIG. Change. However, when the fuel supply state to an arbitrary single cylinder, for example, the first cylinder is abnormal, the crankshaft angular velocity corresponding to the first cylinder decreases as shown by the broken line. Then, the crankshaft angular velocities corresponding to the third cylinder, the second cylinder, and the fourth cylinder gradually increase, and finally the change occurs such that the angular velocities of the crankshafts corresponding to all the cylinders become substantially constant. Therefore, when the angular acceleration of the crankshaft is continuously negative only in any single cylinder in the same driving state, the fuel supply to this single cylinder is abnormal depending on the magnitude. It can be determined that there is.

  The fuel supply abnormality determination method according to the first aspect of the present invention further includes a step of determining whether or not the vehicle is in a predetermined driving state, and is optional only when it is determined that the vehicle is in a predetermined driving state. A step of supplying fuel to one cylinder in a fuel supply pattern for abnormality determination may be performed. In this case, a step of determining whether or not the vehicle is in a predetermined driving state based on the fuel supply pattern set according to the driving state of the vehicle may be performed. Further, in the step of determining whether or not the vehicle is in a predetermined driving state, only the angular acceleration of the crankshaft corresponding to any one cylinder among the angular accelerations of the crankshaft calculated in association with all cylinders is determined. Whether or not there is an abnormality in the supply of fuel to any one cylinder only when the angular acceleration of the crankshaft corresponding to any one cylinder is smaller than the predetermined value. You may make it perform the step to determine. In this case, the arbitrary one cylinder may be a cylinder corresponding to an angular acceleration of the crankshaft smaller than a predetermined value. Alternatively, it is also effective to perform the step of supplying the fuel one cylinder at a time using the fuel supply pattern for abnormality determination, with any one cylinder being all cylinders.

  The fuel supply pattern for abnormality determination is preferably a fuel supply pattern that provides the maximum output torque among a plurality of fuel supply patterns according to the driving state of the vehicle.

  A step of obtaining a correlation between the angular acceleration of the crankshaft and the fuel supply amount for any one cylinder may be performed a predetermined number of times, and a step of averaging the predetermined number of correlations may be further included. . In this case, the step of obtaining a correlation between the fuel supply amount for an arbitrary cylinder and the angular acceleration of the crankshaft of the internal combustion engine calculated in association with the arbitrary cylinder was obtained until this reached a predetermined number of times. Storing the correlation, calculating the difference between the maximum and minimum values of the crankshaft angular acceleration relative to the fuel supply amount, and the maximum value of the crankshaft angular acceleration ratio relative to the fuel supply amount And the step of canceling all the stored correlations when the difference between the minimum value and the minimum value is equal to or greater than a predetermined value.

  According to a second aspect of the present invention, there is provided an apparatus for determining a fuel supply abnormality related to an arbitrary cylinder in a multi-cylinder internal combustion engine in which a plurality of fuel supply patterns are set in accordance with an operating state of the vehicle. An abnormality determination fuel supply amount setting means for supplying fuel with an abnormality determination fuel supply pattern, a crank angle sensor for detecting the rotational phase of the crankshaft of the internal combustion engine, and a detection signal from the crank angle sensor The crankshaft angular acceleration calculating means for calculating the angular acceleration of the crankshaft in association with the arbitrary cylinder, the crankshaft angular acceleration calculated by the crankshaft angular acceleration calculating means, and the abnormality determination A correlation calculation unit that calculates a correlation with the fuel supply amount for an arbitrary cylinder set by the fuel supply amount setting means, and a phase calculated by the correlation calculation unit A fuel supply abnormality determination that determines whether or not there is a fuel supply abnormality for any one cylinder that is supplied with fuel in a fuel supply pattern for abnormality determination by comparing the relationship with a preset reference correlation It is characterized by having a part.

  In the present invention, regardless of the fuel supply pattern set according to the driving state of the vehicle, the abnormality determination fuel supply amount setting means supplies fuel to an arbitrary cylinder in the abnormality determination fuel supply pattern. To do. The crankshaft angular acceleration calculating means calculates the angular acceleration of the crankshaft in association with an arbitrary cylinder from the rotational phase of the crankshaft of the internal combustion engine detected by the crank angle sensor. The correlation calculation unit calculates a correlation between the crankshaft angular acceleration calculated by the crankshaft angular acceleration calculation means and the fuel supply amount for any one cylinder set by the abnormality determination fuel supply amount setting means. calculate. The fuel supply abnormality determination unit compares the correlation calculated by the correlation calculation unit with a preset reference correlation, thereby arbitrarily supplying fuel in the abnormality determination fuel supply pattern. The presence or absence of fuel supply abnormality to one cylinder is determined. More specifically, when the correlation calculated by the correlation calculation unit is greatly deviated from a correlation that is a preset reference, an arbitrary fuel is supplied in the abnormality determination fuel supply pattern. It is determined that there is an abnormality in fuel supply to one cylinder.

  In the fuel supply abnormality determination device according to the second aspect of the present invention, the correlation calculation unit stores a predetermined number of calculated correlations, and averages the correlation stored in the storage unit to average correlation And an average correlation calculation unit that calculates the relationship. In this case, the correlation calculation unit is a maximum difference calculation unit that calculates a difference between a maximum value and a minimum value of the angular acceleration of the crankshaft with respect to the fuel supply amount for abnormality determination supplied to any one cylinder, The memory may further include a storage canceling unit that compares the difference calculated by the maximum difference calculating unit with a predetermined value and cancels all the correlations stored in the storage unit when the difference is equal to or larger than the predetermined value.

  According to the present invention, fuel is supplied to an arbitrary cylinder in a fuel supply pattern for abnormality determination, the angular acceleration of the crankshaft of the internal combustion engine is calculated in association with the arbitrary cylinder, and the calculated crank Find the correlation between the angular acceleration of the shaft and the amount of fuel supplied to any one cylinder, compare the calculated correlation with a preset correlation, and check whether there is any abnormal fuel supply to any one cylinder. Since the determination is made, the multi-cylinder internal combustion engine is controlled in a state in which the adverse effect on the vehicle is minimized while suppressing the reduction in fuel consumption even during the traveling by the fuel supply pattern set according to the driving state of the vehicle. It is possible to quickly determine a fuel supply abnormality related to an arbitrary cylinder in the engine.

  A step of determining whether or not the vehicle is in a predetermined driving state is provided, and only when it is determined that the vehicle is in a predetermined driving state, fuel is supplied with an abnormality determination fuel supply pattern for any one cylinder. When performing the step of determining whether or not the vehicle is in a predetermined driving state based on the fuel supply pattern set according to the driving state of the vehicle, An adverse effect on the vehicle can be further reliably suppressed. Further, in the step of determining whether or not the vehicle is in a predetermined driving state, only the angular acceleration of the crankshaft corresponding to any one cylinder among the angular accelerations of the crankshaft calculated in association with all cylinders is determined. Whether or not there is an abnormality in the supply of fuel to any one cylinder only when the angular acceleration of the crankshaft corresponding to any one cylinder is smaller than the predetermined value. When the determination step is performed, it is possible to reliably determine the fuel supply abnormality related to any one cylinder in the multi-cylinder internal combustion engine. In particular, when any one cylinder is a cylinder corresponding to the angular acceleration of the crankshaft smaller than a predetermined value, it is possible to more quickly determine the fuel supply abnormality related to any one cylinder in the multi-cylinder internal combustion engine. Alternatively, when any one cylinder is all cylinders and the step of supplying fuel in the fuel supply pattern for abnormality determination is performed for all cylinders one by one, any one cylinder in the multi-cylinder internal combustion engine This makes it possible to determine the fuel supply abnormality with high reliability.

  When the fuel supply pattern for abnormality determination is a fuel supply pattern that can obtain the maximum output torque among a plurality of fuel supply patterns according to the driving state of the vehicle, it is possible to suppress a reduction in fuel consumption to a minimum.

  An embodiment in which a fuel supply abnormality determination device according to the present invention is applied to a vehicle equipped with a compression ignition internal combustion engine will be described in detail with reference to FIGS. However, the present invention is not limited to such an embodiment, and can be applied to any other technique belonging to the spirit of the present invention.

  The concept of the engine system in this embodiment is shown in FIG. 2, and the control block in this engine system is shown in FIG. The engine 10 in the present embodiment is a compression ignition type four-cylinder internal combustion engine that spontaneously ignites by directly injecting light oil as fuel into the combustion chamber 12 in a compressed state from the fuel injection valve 11. However, due to the characteristics of the present invention, any multi-cylinder internal combustion engine may be used as long as the number of cylinders is other than a single cylinder. In the engine 10, combustion is performed using an exhaust gas recirculation (EGR) device 15 that guides a part of the exhaust gas flowing in the exhaust passage 13 into the intake passage 14 and kinetic energy of the exhaust gas flowing in the exhaust passage 13. A turbocharger (not shown) for supercharging the chamber 12 is incorporated.

  In the engine system of the present embodiment, a plurality of fuel supply patterns as shown in Table 2 below are set according to the driving state of the vehicle.

  For this reason, the fuel injection mode setting unit 17 of the electronic control unit (hereinafter referred to as ECU) 16 sets an injection mode according to the driving state of the vehicle among a plurality of types of injection modes, and sets this as the fuel injection amount. To the unit 18. The fuel injection amount setting unit 18 of the ECU 16 sets the fuel injection amount and the injection timing from the fuel injection valve 11 for each cylinder based on the set injection mode, and also includes an abnormality determination fuel injection amount setting unit. Including. The abnormality determination fuel injection amount setting unit as the abnormality determination fuel supply amount setting means in the present invention is abnormal only for an arbitrary cylinder regardless of the injection mode set by the fuel injection mode setting unit 17. A fuel injection amount for determination is set. The fuel injection amount for abnormality determination in the present embodiment is set to be the same as that in the single injection mode, but is not limited to this, and can be set to be the same as in the first multi-injection mode, for example. . In any case, it is effective to perform fuel supply so that a change when an abnormality occurs appears remarkably. The fuel injection valve drive control unit 19 of the ECU 16 controls the operation of the fuel injection valve 11 so that the fuel of the injection amount set by the fuel injection amount setting unit 18 is injected at the set injection timing.

  The EGR device 15 has one end communicating with the exhaust pipe 20 that defines the main part of the exhaust passage 13 and the other end communicating with the inside of the intake pipe 21 that defines the main part of the intake passage 14, and the EGR path 22. An EGR tube 23 is defined. The EGR device 15 also includes an EGR valve 24 that is provided in the EGR pipe 23 and controls the flow rate of exhaust gas flowing through the EGR passage 22. In the present embodiment, when the EGR determination unit 25 of the ECU 16 determines that the vehicle on which the engine 10 is mounted is in a preset EGR operation region, the opening degree of the EGR valve 24 depends on the operation state of the vehicle. It is set by the EGR amount setting unit 26. The EGR valve drive control unit 27 of the ECU 16 controls the EGR valve 24 to the opening set by the EGR amount setting unit 26, and otherwise holds the EGR passage 22 basically closed so as to close the EGR passage 22. To do.

  The cylinder head 30 in which the intake port 28 and the exhaust port 29 facing the combustion chamber 12 are formed has a valve operating mechanism (not shown) including an intake valve 31 that opens and closes the intake port 28 and an exhaust valve 32 that opens and closes the exhaust port 29. It has been incorporated. The cylinder head 30 is provided with a fuel injection valve 11 facing the center of the upper end of the combustion chamber 12 so as to be sandwiched between the intake valve 31 and the exhaust valve 32. The valve operating mechanism in the present embodiment can change the opening / closing timings of the intake valve 31 and the exhaust valve 32 according to the operating state of the engine 10, but these opening / closing timings may be fixed. .

  At the upstream end side of the intake pipe 21 connected to the cylinder head 30 so as to communicate with the intake port 28 and defining the intake passage 14 together with the intake port 28, dust and the like contained in the atmosphere are removed to remove the intake passage 14. An air filter 33 is provided for guiding the air. The other end of the EGR pipe 23 described above is connected to the intake pipe 21 between the intake port 28 and a surge tank 34 formed in the middle of the intake pipe 21.

In the middle of the exhaust pipe 20 connected to the cylinder head 30 so as to communicate with the exhaust port 29 and defining the exhaust passage 13 together with the exhaust port 29, harmful substances generated by the combustion of the air-fuel mixture in the combustion chamber 12 are present. A detoxifying catalyst 35 is incorporated. As the catalyst 35, not only common oxidation catalysts in diesel engines, DPR (D iesel P articulate active R eduction system) or DPNR (D iesel P articulate- N O x R eduction System) DPF used in such (D it is also possible to adopt a iesel P articulate F ilter). Note that one end of the EGR pipe 23 described above is connected to the exhaust pipe 20 upstream of the catalyst 35.

Accordingly, the intake air supplied from the intake pipe 21 into the combustion chamber 12 through the air filter 33 together with the exhaust gas recirculated into the intake pipe 21 via the EGR pipe 23 is transferred from the fuel injection valve 11 into the combustion chamber 12. It forms an air-fuel mixture with the injected fuel. Then, the piston 36 spontaneously ignites and burns immediately before the compression top dead center of the piston 36, and the exhaust gas generated thereby passes through the catalyst 35 and is discharged from the exhaust pipe 20 into the atmosphere. In this case, since the combustion temperature of the air-fuel mixture is reduced by CO ₂ contained in the intake air, generation of nitrogen oxides due to the combustion of the air-fuel mixture is suppressed.

  In this embodiment, the ECU 16 grasps the operating state of the engine 10 and the vehicle on which the engine 10 is mounted, and the ECU 16 controls the fuel injection amount and injection timing from the fuel injection valve 11, the opening degree of the EGR control valve 24, and the like. For this purpose, various sensors as described below are further provided. That is, an accelerator opening sensor 38 that detects the amount of depression of the accelerator pedal 37 that is operated by the driver and outputs this to the ECU 16 is provided. Further, an air flow meter 39 for detecting the amount of intake air flowing through the intake passage 14 and outputting it to the ECU 16 is attached in the middle of the intake passage 14 between the air filter 33 and the surge tank 34. In addition, the attachment position of the air flow meter 39 with respect to the intake pipe 21 should just be downstream from the attachment position of the air filter 33, and is not limited to a position like FIG. A crank angle sensor 43 that detects the rotational phase of a crankshaft 42 to which the piston 36 is coupled via a connecting rod 41 and outputs the detected rotational phase to the ECU 16 is attached to the cylinder block 40 in which the piston 36 reciprocates. Yes.

  The ECU 16 includes a microcomputer including a CPU, ROM, RAM, A / D converter, input / output interface, and the like (not shown). The ECU 16 performs predetermined arithmetic processing based on detection signals from the sensors 38 and 43 and the air flow meter 39 described above so that the engine 10 can be operated smoothly. Then, the operation of the fuel injection valve 11 and the EGR valve 24 is controlled according to a preset program. In addition, in order to determine the fuel supply abnormality related to an arbitrary cylinder in the engine 10, the ECU 16 in the present embodiment, in addition to the fuel injection amount setting unit 18 described above, an operating state determination unit 44 and a crankshaft angular acceleration calculation unit. 45, a correlation ratio calculation unit 46, a fuel supply abnormality determination unit 47, and a warning indicator drive control unit 48.

The driving state determination unit 44 including the above-described EGR determination unit 25 determines the driving state of the vehicle and outputs it to the fuel injection mode setting unit 17 and the EGR amount setting unit 26. It is determined whether or not it is in an operating state. In the present embodiment, the fuel supply amount set by the fuel injection amount setting unit 18 is a predetermined amount or more, the rate of change of the intake air amount detected by the air flow meter 39 is substantially constant, and the accelerator opening sensor When the rate of change of the accelerator opening detected by 38 is substantially constant, it is determined that the vehicle is in a predetermined operating state, that is, in a steady running state in the present embodiment. Further, in the present embodiment, only the angular acceleration α of the crankshaft 42 corresponding to an arbitrary single cylinder is smaller than a preset negative angular acceleration (hereinafter referred to as determination reference angular acceleration) α _R. It is included in the predetermined operation state. This determination reference angular acceleration α _R is a relatively large absolute value that cannot occur when abnormality occurs in two or more cylinders at the same time.

  The crankshaft angular acceleration calculation unit 45 calculates the angular acceleration α of the crankshaft 42 in association with each cylinder on the basis of the detection signal from the crank angle sensor 43, and this is calculated as an operating state determination unit 44 and a correlation ratio calculation unit. Output to 46.

The correlation ratio calculation unit 46 calculates the angular acceleration ratio γ of the crankshaft 42 calculated by the crankshaft angular acceleration calculation unit 45 with respect to the fuel injection amount for each cylinder set by the fuel injection amount setting unit 18. Therefore, information related to the fuel injection amount set by the fuel injection amount setting unit 18 is also input to the correlation ratio calculation unit 46. The correlation ratio calculation unit 46 includes a storage unit 49, an average correlation ratio calculation unit 50, and a maximum difference calculation unit 51. Storage unit 49, although the percentage gamma calculated in which a predetermined number of stored values calculated by the maximum difference calculating section 51 is compared with a predetermined value gamma _C, if this is below the predetermined value gamma _C, it A storage cancel unit 52 that cancels all the ratios γ _n stored up to is included. The average correlation ratio calculation unit 50 averages the ratio γ stored in the storage unit 49 by the least square method or the like, and calculates the average ratio γ _m . The maximum difference calculation unit 51 calculates a difference between the maximum value γ _max and the minimum value γ _min of the angular acceleration ratio γ of the crankshaft 42 with respect to the fuel injection amount, and outputs the difference to the storage cancellation unit 52.

The results calculated by the correlation ratio calculation unit 46 are schematically shown in FIG. This is because the set fuel injection amount set by the fuel injection amount setting unit 18 supplied to the cylinder in which the crankshaft angular acceleration α is negative during operation of the vehicle in the single injection mode, and the crankshaft angle The relationship with the acceleration α is schematically shown. That is, when the vehicle is in a steady running state and the fuel supply is abnormal to a predetermined cylinder, for example, the correlation ratio γ _U is plotted in a region Z _U indicated by hatching and stored in the storage unit 49. These average values calculated by the average correlation ratio calculating unit 50 are indicated by a straight line L _U. Note that when the fuel is normally supplied into the cylinder, the crankshaft angular acceleration α is almost zero, and therefore the relationship between the set fuel injection amount supplied to the cylinder and the crankshaft angular acceleration α. Are plotted in the area Z _N indicated by halftone dots, and these correlation ratios γ _n are stored in the storage unit 49. These average values calculated by the average correlation ratio calculation unit 50 are indicated by a straight line L _N and are generally parallel to the horizontal axis of the graph. Further, when the vehicle is operating in the multi-injection mode, these correlation ratios γ _R are plotted in a region Z _R indicated by a reverse oblique line and stored in the storage unit 49. These average values calculated by the average correlation ratio calculation unit 50 are indicated by a straight line L _R. That is, the magnitude of the inclination angle of the straight lines L _U and L _R with respect to the straight line L _N is a material for determining fuel supply abnormality in each traveling state of the vehicle.

  As can be seen from FIG. 4, in the case of the operating state in the single injection mode, the inclination angle appears larger than in the operating state in the other multi-injection modes, so that it is understood that the accuracy of abnormality determination is increased. In the present invention, even in an operation state in a specific multi-injection mode, only a specific single cylinder is supplied with fuel in the single injection mode, and a crank angular acceleration α corresponding to the single cylinder is calculated. Therefore, even if fuel is supplied to only a single cylinder with the fuel supply pattern for abnormality determination, it is possible to accurately determine abnormality in fuel supply without significantly reducing drivability. However, in the present embodiment, during operation in the second and fifth multi-injection modes, fuel supply abnormality determination is not performed in order to avoid a decrease in drivability and a deterioration in emissions. However, it goes without saying that the fuel supply abnormality determination as described above can be performed in all fuel injection modes if the decrease in drivability and the deterioration in emissions do not matter.

The fuel supply abnormality determination unit 47 includes a reference correlation ratio γ _R that serves as a reference for the angular acceleration of the crankshaft 42 corresponding to the fuel injection amount for each cylinder according to the operation state of the engine 10 determined by the operation state determination unit 44. Is remembered. The fuel supply abnormality determination unit 47 compares the reference correlation ratio γ _R stored here with the average ratio γ _m calculated by the correlation ratio calculation unit 46, and determines the fuel supply abnormality regarding an arbitrary single cylinder. Determine presence or absence. In other words, when the inclination angle of the straight line L _U for linear L _N shown in FIG. 4 is a predetermined value or more, determined in particular when the average ratio gamma _m is equal to or larger than the reference correlation ratio gamma _R, there is a supply abnormality of the fuel To do.

  The warning indicator drive control unit 48 is for notifying the driver that there is an abnormality in the fuel supply state to the engine 10 based on the determination result of the fuel supply abnormality determination unit 47, and a warning indicator 53 for that purpose. Is provided in a vehicle interior (not shown). The warning indicator 53 may be any device that can alert the driver of the vehicle using hearing or vision.

  The fuel supply abnormality setting procedure in this embodiment will be described with reference to FIGS. 5 to 7. First, in the step of S 11, whether or not the vehicle is in a predetermined driving state is determined by the driving state determination unit 44. judge. If it is determined that the vehicle is not in a predetermined driving state, that is, the vehicle is in a transient state such as during acceleration / deceleration, this routine is terminated without doing anything.

On the other hand, when it is determined that the vehicle is in the predetermined driving state, the process proceeds to step S12, and the crankshaft angular acceleration calculation unit 45 calculates the crankshaft angular acceleration α. one cylinder only, it determines whether the corresponding crankshaft angular acceleration alpha is smaller than the determination reference angular acceleration alpha _R. Only any single cylinder in this S13 in step is crankshaft angular acceleration alpha determination reference angular acceleration alpha _R above, i.e. or a crankshaft angular acceleration plurality of cylinders alpha is not a slightly negative respectively, all cylinders If it is determined that the crankshaft angular speed α corresponding to is all positive or zero, this routine is terminated without doing anything.

On the other hand, when it is determined in step S13 that the crankshaft angular acceleration α is smaller than the determination reference angular acceleration α _{R for} only a single cylinder, the process proceeds to step S14 and the current fuel injection mode is set to a predetermined value. It is determined whether the fuel injection mode, that is, the single injection mode capable of determining the fuel supply abnormality, or the first, third, and fourth injection modes. When the fuel injection mode set by the fuel injection mode setting unit 17 is either the second or fourth multi-injection mode, this routine is finished without doing anything.

On the other hand, when the injection mode set by the fuel injection mode setting unit 17 is either the single injection mode or the first, third, and fourth injection modes, the process proceeds to step S15 to determine abnormality. It is determined whether the cylinder flag is set. At first, since the operation state determination flag is not set, the routine proceeds to step S16, where the abnormality determination cylinder flag F is set to F1, and only the first cylinder is set to the fuel supply mode for abnormality determination at step S17. In step S18, the correlation ratio calculation unit 46 calculates the correlation ratio γ _n corresponding to the crankshaft angular acceleration α of the first cylinder, and in step S19, the counter is incremented. Then, the maximum / minimum correlation ratio setting for setting the maximum value and the minimum value of the correlation ratio is performed in step S20.

A detailed procedure for setting the maximum / minimum correlation ratio in the step of S20 is shown in FIG. 7, which is performed by the maximum difference calculation unit 51 of the storage unit 49. First, in step S201, it is determined whether or not the count value C _{n of the} counter is 1. At first, since the count value C _n is 1, the process proceeds to step S202, and after setting the correlation ratio γ ₁ calculated in step S18 to the maximum correlation ratio γ _max , the main routine shown in FIG. Return. Further, if the count value C _n at step counter in S201 is determined not to be 1, this time the process proceeds to S203 of determining whether or not the count value C _n of the counter is 2. Here, when it is determined that the count value C _n of the counter is 2, it is determined whether or not the maximum value γ _max of the correlation ratio set in step S202 is equal to or larger than the correlation ratio γ ₂ calculated this time. Judgment is made in the step.

In step S204, the correlation ratio maximum value γ _max is smaller than the correlation ratio γ ₂ , that is, the correlation ratio γ ₂ calculated this time is larger than the correlation ratio maximum value γ _max initially set (absolute If it is determined that the value is small, the process proceeds to step S205. Then, after setting the correlation ratio γ ₂ calculated this time to the minimum value γ _min of the correlation ratio, this subroutine is terminated. The maximum value gamma _max of the correlation ratio correlation ratio gamma ₂ or more at S204 step, i.e. the calculated correlation ratio gamma ₂ is large initially equal to or less than the maximum value gamma _max of the correlation ratio is set to (the absolute value current ), The process proceeds to step S206. Then, the correlation ratio γ ₂ calculated this time is set to the maximum value γ _max of the correlation ratio, and the correlation ratio γ ₁ calculated last time, that is, the maximum value γ _max of the previous correlation ratio is set to the minimum value γ _min of the correlation ratio. After resetting, this subroutine is terminated.

The count value of the counter at S203 step C _n is not a 2, i.e., if the count value C _n of the counter is determined to be 3 or more, the maximum value gamma _max of the correlation ratio shifts to S207 step It is determined whether or not the correlation ratio γ _n calculated this time is _{equal to} or greater. Here, the maximum value γ _max of the correlation ratio is equal to or greater than the correlation ratio γ ₂ calculated this time, that is, the correlation ratio γ ₂ calculated this time is smaller than the maximum value γ _max of the correlation ratio initially set ( If it is determined that the absolute value is large, the process proceeds to step S208. Then, after resetting the correlation ratio γ _n calculated this time to the maximum value γ _max of the correlation ratio, this subroutine is terminated.

If it is determined in step S207 that the maximum correlation ratio value γ _max is smaller than the currently calculated correlation ratio γ _n , the process proceeds to step S209 where the minimum correlation ratio value γ _min is calculated this time. It is determined whether or not the correlation ratio is greater than γ _n . The correlation ratio minimum value γ _min is larger than the currently calculated correlation ratio γ _n , that is, the correlation ratio γ _n calculated this time is smaller than the already set correlation ratio minimum value γ _min (the absolute value is large). ), The process proceeds to step S210. Then, after resetting the correlation ratio γ _n calculated this time to the minimum value γ _min of the correlation ratio, this subroutine is terminated. Note that the correlation ratio γ _n calculated this time in step S209 is equal to or greater than the minimum value γ _{min of the} correlation ratio, that is, whether the correlation ratio γ _n calculated this time is the maximum value γ _max or the minimum value γ _{min of the} correlation ratio. If it is determined that there is no, this subroutine is terminated without doing anything.

Thus, after setting the maximum value γ _max and the minimum value γ _{min of the} correlation ratio in step S20, the process proceeds to step S21. Then, the maximum difference calculation unit 51 of the storage unit 49 determines whether or not a value obtained by subtracting the minimum correlation rate value γ _min from the maximum correlation rate value γ _max is larger than the reset determination value γ _C (<0). To do. Here, the value obtained by subtracting the minimum correlation ratio value γ _min from the maximum correlation ratio value γ _max is equal to or less than the reset determination value γ _C , that is, the calculated correlation ratio γ _n value may be abnormal. If so, the process proceeds to step S22. Then, after canceling all the correlation ratios γ _n stored in the storage unit 49 by the storage cancel unit 52 and resetting the count value C _{n of the} counter to 0, the processing after step S11 is resumed.

In step S21, the value obtained by subtracting the minimum correlation ratio value γ _min from the maximum correlation ratio value γ _max is larger than the reset determination value γ _C , that is, the calculated correlation ratio γ _n is determined not to be abnormal. when determines the count value C _n of shifts counter to step S23, whether or not reached a predetermined value C _R. Since the initial value is equal to or less than the predetermined value C _R , the process proceeds to step S24, the correlation ratio γ _n calculated in step S18 is stored in the storage unit 49, and the processes after step S11 are repeated again. .

If at S23 in step count value C _n of the counter is determined to have reached the predetermined value C _R is calculated by migrated average correlation ratio calculating unit 50 the average correlation ratio gamma _m and the step S25 . Then, in step S26, the fuel supply abnormality determination unit 47 determines whether or not the average correlation ratio γ _m is equal to or greater than a preset abnormality determination reference angular acceleration γ _R. Here, the fuel supply amount to the cylinder in which the average correlation ratio γ _m is smaller than the abnormality determination reference angular acceleration γ _R , that is, the crankshaft angular acceleration α is smaller than the determination reference angular acceleration α _R is abnormal. If the fuel supply abnormality determination unit 47 determines, the process proceeds to step S27. Then, the warning indicator drive control unit 48 activates the warning indicator 53, so that the driver can make a determination to request inspection and maintenance of the fuel supply system at the maintenance shop according to the display of the warning indicator 53. . Further, in step S26, the average correlation ratio γ _m is equal to or greater than the abnormality determination reference angular acceleration γ _R , that is, the amount of fuel supplied to the cylinder in which the negative crankshaft angular acceleration α is negative is not abnormal. If it is determined, the process proceeds to step S28. Then, after resetting the count value C _{n of the} counter to 0, the process proceeds to step S29, and it is determined whether or not the abnormality determination cylinder flag F is set to F1. Since the abnormality determination cylinder flag F is initially set to F1, the process proceeds to step S30, and after the abnormality determination cylinder flag F is set to F2, only the second cylinder fuel injection mode for abnormality determination is set in step S31. Set to. And the process after S11 is performed again.

  If it is determined in step S29 that the abnormality determination cylinder flag F is not set to F1, the process proceeds to step S32, and it is determined whether or not the abnormality determination cylinder flag F is set to F2. If it is determined that the abnormality determination cylinder flag F is set to F2, the process proceeds to step S33. After the abnormality determination cylinder flag F is set to F3, only the third cylinder is determined to be abnormal in step S34. Set to fuel injection mode. And the process after S11 is performed again.

  Similarly, when it is determined in step S32 that the abnormality determination cylinder flag F is not set to F2, the process proceeds to step S35, and whether or not the abnormality determination cylinder flag F is set to F3. Determine. If it is determined that the abnormality determination cylinder flag F is set to F2, the process proceeds to step S36, and after the abnormality determination cylinder flag F is set to F4, only the fourth cylinder is determined to be abnormal in step S37. Set to fuel injection mode. And the process after S11 is performed again.

  In step S35, the abnormality determination cylinder flag F is not set to F3, that is, determination of the presence or absence of fuel supply abnormality for all the cylinders has been completed. Therefore, in step S38, the abnormality determination cylinder flag is reset, Control starts again from the very beginning.

As described above, in the above-described embodiment, when it is determined that the crankshaft angular acceleration α is smaller than the determination reference angular acceleration α _{R for} only any single cylinder, one cylinder is forcibly single-injected sequentially to all the cylinders. To determine whether or not there is an abnormality in fuel supply to any single cylinder. For this reason, although a highly reliable determination result can be obtained, there also arises a problem that it takes time to complete the determination of the presence or absence of fuel supply abnormality for all the cylinders. Therefore, if only a single cylinder crankshaft angular acceleration alpha was determined to be smaller than the determination reference angular acceleration alpha _R, corresponding fuel for only abnormality determination single cylinder is determined to be smaller than the determination reference angular acceleration alpha _R The injection mode may be set, and the presence or absence of fuel supply abnormality may be determined for this single cylinder. In this case, it is possible to determine the presence or absence of fuel supply abnormality in a short time, but the reliability of the determination result may be lower than in the previous embodiment. Further, in the above-described embodiment, the case where the present invention is applied to a compression ignition engine has been described. However, the direct injection type spark ignition engine using an ignition plug using gasoline, alcohol, LPG (liquefied natural gas) or the like as fuel is described. Even it is effective. In such a spark ignition engine, it goes without saying that the same effect as that of the diesel engine described above can be obtained.

  The present invention should be construed only from the matters described in the scope of the claims, and in the above-described embodiments, all the changes and modifications included in the concept of the present invention are possible other than the matters described. It is. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

6 is a graph schematically showing a relationship between a crankshaft phase and a crankshaft angular velocity. It is a system conceptual diagram of one embodiment which applied the present invention to a compression ignition type internal combustion engine. FIG. 3 is a control block diagram in the embodiment shown in FIG. 2. 6 is a graph schematically showing a relationship between a fuel injection amount and crank angular acceleration. It is a flowchart showing the control procedure in this embodiment with FIG. It is a flowchart showing the control procedure in this embodiment with FIG. 6 is a flowchart showing details of a maximum / minimum correlation ratio setting subroutine shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Fuel injection valve 12 Combustion chamber 13 Exhaust passage 14 Intake passage 15 Exhaust gas recirculation (EGR) apparatus 16 ECU
DESCRIPTION OF SYMBOLS 17 Fuel injection mode setting part 18 Fuel injection amount setting part 19 Fuel injection valve drive control part 20 Exhaust pipe 21 Intake pipe 22 EGR passage 23 EGR pipe 24 EGR valve 25 EGR determination part 26 EGR amount setting part 27 EGR valve drive control part 28 Intake port 29 Exhaust port 30 Cylinder head 31 Intake valve 32 Exhaust valve 33 Air filter 34 Surge tank 35 Catalyst 36 Piston 37 Accelerator pedal 38 Accelerator opening sensor 39 Air flow meter 40 Cylinder block 41 Connecting rod 42 Crankshaft 43 Crank angle sensor 44 Operation State determination unit 45 Crankshaft angular acceleration calculation unit 46 Correlation ratio calculation unit 47 Fuel supply abnormality determination unit 48 Warning indicator drive control unit 49 Storage unit 50 Average correlation ratio calculation unit 51 Maximum difference calculation unit 52 Storage cancellation unit 53 Warning indicator

Claims (8)

A method of determining a fuel supply abnormality related to an arbitrary cylinder in a multi-cylinder internal combustion engine in which a plurality of fuel supply patterns are set according to a driving state of a vehicle,
Supplying fuel to an arbitrary cylinder in a fuel supply pattern for abnormality determination;
Calculating the angular acceleration of the crankshaft of the internal combustion engine in association with the arbitrary cylinder;
Obtaining a correlation between the calculated angular acceleration of the crankshaft and the fuel supply amount for the arbitrary cylinder;
A fuel supply abnormality determination method comprising: comparing the obtained correlation with a preset correlation and determining whether or not there is an abnormality in fuel supply to an arbitrary cylinder.   The method further includes the step of determining whether or not the vehicle is in a predetermined driving state, wherein the step of supplying fuel to an arbitrary cylinder in a fuel supply pattern for abnormality determination is performed when the vehicle is in a predetermined driving state. 2. The fuel supply abnormality determination method according to claim 1, wherein the determination is performed only when it is determined that there is a fuel supply abnormality.   The fuel supply abnormality according to claim 2, wherein the step of determining whether or not the vehicle is in a predetermined driving state is performed based on a fuel supply pattern set in accordance with the driving state of the vehicle. Judgment method. In the step of determining whether or not the vehicle is in a predetermined driving state, only the angular acceleration of the crankshaft corresponding to any one cylinder is predetermined among the angular accelerations of the crankshaft calculated in association with all the cylinders. Determining whether it is less than a value,
The step of determining whether or not there is an abnormality in fuel supply to any one cylinder is performed only when the angular acceleration of the crankshaft corresponding to any one cylinder is smaller than a predetermined value. Alternatively, the fuel supply abnormality determination method according to claim 3.   The fuel supply abnormality determination method according to claim 4, wherein the one arbitrary cylinder is a cylinder corresponding to an angular acceleration of a crankshaft smaller than a predetermined value.   5. The fuel according to claim 4, wherein the one arbitrary cylinder is all cylinders, and the step of supplying fuel in a fuel supply pattern for abnormality determination is performed for all cylinders one by one. Supply abnormality judgment method.   7. The fuel supply pattern for determining an abnormality is a fuel supply pattern capable of obtaining a maximum output torque among a plurality of fuel supply patterns according to a driving state of the vehicle. The fuel supply abnormality determination method according to claim 1. An apparatus for determining a fuel supply abnormality related to an arbitrary cylinder in a multi-cylinder internal combustion engine in which a plurality of fuel supply patterns are set according to a driving state of a vehicle,
An abnormality determination fuel supply amount setting means for supplying fuel in an abnormality determination fuel supply pattern to an arbitrary cylinder;
A crank angle sensor for detecting the rotational phase of the crankshaft of the internal combustion engine;
Crankshaft angular acceleration calculating means for calculating the angular acceleration of the crankshaft in association with the arbitrary one cylinder based on the detection signal from the crank angle sensor;
Correlation for calculating the correlation between the fuel supply amount for an arbitrary cylinder set by the abnormality determination fuel supply amount setting means and the angular acceleration of the crankshaft calculated by the crankshaft angular acceleration calculation means A calculation unit;
By comparing the correlation calculated by this correlation calculation unit with the correlation that is set in advance, the fuel of any one cylinder that has been supplied with the fuel supply pattern for abnormality determination is determined. A fuel supply abnormality determination device comprising: a fuel supply abnormality determination unit that determines whether or not there is a supply abnormality.

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