Device for determining injection abnormality in an internal combustion engine

Abstract

To provide an injection abnormality determination device capable of determining presence or absence of abnormality in injection quantity with high accuracy.SOLUTION: A CPU calculates an instantaneous speed ω as a rotating speed of a crank shaft at an interval of 30°CA at a cycle of 30°CA (S12). The CPU calculates an energy change rate equivalent amount D1 in a case of ATDC30°CA of any of cylinders (S22). The energy change rate equivalent amount D1 is a change rate of a square of an instantaneous speed ω. Then, the CPU calculates a difference amount D2 as a difference between the energy change rate equivalent amounts D1 (S24). Then, the CPU determines whether the difference amount D2 is smaller than a threshold value Dth or not (S26). In a case when the difference amount is smaller than the threshold value Dth, the CPU determines that it is a lean abnormality (S30).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an injection abnormality determination device for an internal combustion engine. [Background technology]

[0002] Conventionally, a device has been proposed for determining whether or not there is an abnormality in which the fuel injection amount of an internal combustion engine deviates from a target injection amount. For example, the following Patent Document 1 describes that an abnormality is determined when a fluctuation parameter indicating the degree of unevenness in the rotation speed of the output shaft of the internal combustion engine exceeds a predetermined reference value (paragraph "0004"). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-185554 A Summary of the Invention [Problem to be solved by the invention]

[0004] The fluctuation parameter quantifies the fluctuation during the interval between occurrences of the compression top dead center or a period equal to an integer multiple of the interval. Therefore, the fluctuation parameter includes the effect of disturbances acting on the crankshaft during a period having the length of the interval between occurrences of the compression top dead center. Therefore, there is a risk that the accuracy of determining whether or not an abnormality exists will decrease due to disturbances. [Means for solving the problem]

[0005] Means for solving the above problems and their effects will be described below. The device is applied to an internal combustion engine having a plurality of cylinders and executes a speed acquisition process, an energy change rate equivalent calculation process, a difference amount calculation process, and a judgment process, wherein the speed acquisition process is a process for acquiring the rotational speed of a crankshaft of the internal combustion engine, the energy change rate equivalent calculation process is a process for calculating an energy change rate equivalent, which is a variable indicating a change over time of an amount proportional to the square of the rotational speed, the difference amount calculation process is a process for calculating a difference amount, which is an amount proportional to the difference between a pair of energy change rate equivalent amounts before and after one compression top dead center, and the judgment process is a process for determining whether or not there is an abnormality in the fuel injection amount of the internal combustion engine based on a comparison of the magnitude of the difference amount and a threshold value.

[0006] The value of the energy change rate equivalent before the compression top dead center indicates the amount of energy loss per unit time when there is no element that accelerates the rotation of the crankshaft by the combustion energy and the rotation speed is reduced by a force that hinders the rotation of the crankshaft. On the other hand, the value of the energy change rate equivalent after the compression top dead center indicates the amount of increase in the rotational energy of the crankshaft per unit time when the rotation of the crankshaft is accelerated by the combustion energy. Therefore, the pair of energy change rate equivalents have different signs. Therefore, the difference value of the pair of energy change rate equivalents is a value obtained by adding the absolute value of the amount of energy loss to the amount of increase in the rotational energy of the crankshaft per unit time. This corresponds to the combustion energy. Therefore, the amount of combustion energy can be compared with the threshold value based on the comparison of the difference amount with the threshold value. Therefore, the presence or absence of an abnormality in the injection amount can be determined with high accuracy. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing the configuration of a control device and a drive system according to one embodiment. [Diagram 2] 4 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. [Diagram 3] 4 is a time chart for explaining an abnormality determination according to the embodiment; [Figure 4] FIG. 13 is a diagram showing the relationship between the difference amount and a threshold value according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment will be described with reference to the drawings. As shown in FIG. 1, an internal combustion engine 10 has four cylinders #1 to #4. Air in an intake passage 12 of the internal combustion engine 10 is drawn into each combustion chamber 14 of the cylinders #1 to #4. A fuel injection valve 16 protrudes into the combustion chamber 14, and a mixture of fuel injected from the fuel injection valve 16 and air drawn into the combustion chamber 14 from the intake passage 12 is combusted by spark discharge from an ignition device 18. Energy generated by the combustion is converted into rotational energy of a crankshaft 20. The combusted mixture is discharged to an exhaust passage 22 as exhaust gas.

[0009] A crank rotor 30 is coupled to the crankshaft 20. The crank rotor 30 is provided with teeth 32. The teeth 32 indicate each of a plurality of rotation angles of the crankshaft 20. The crank rotor 30 is basically provided with teeth 32 at intervals of 10° CA, but is provided with one missing tooth portion 34 where the interval between adjacent teeth 32 is 30° CA. This is for indicating a reference rotation angle of the crankshaft 20.

[0010] A planetary gear mechanism 40 constituting a power split device is mechanically connected to the crankshaft 20 via a damper 36. The damper 36 is provided with a coil spring and exerts elastic force. The planetary gear mechanism 40 splits the power of the internal combustion engine 10, the first motor generator 50, and the second motor generator 60. The carrier C of the planetary gear mechanism 40 is mechanically connected to the crankshaft 20 via the damper 36. A rotating shaft 52 of the first motor generator 50 is mechanically connected to a sun gear S of the planetary gear mechanism 40. A rotating shaft 62 of the second motor generator 60 is mechanically connected to a ring gear R of the planetary gear mechanism 40. The output voltage of the first inverter 54 is applied to the terminals of the first motor generator 50. The output voltage of the second inverter 64 is applied to the terminals of the second motor generator 60.

[0011] In addition to the rotating shaft 62 of the second motor generator 60, the ring gear R of the planetary gear mechanism 40 is mechanically connected to the drive wheels 44 via a transmission . The control device 70 operates various operating parts of the internal combustion engine 10 to control the torque, exhaust component ratio, and the like, which are control variables of the internal combustion engine 10 as a control object. The control device 70 also operates the hydraulic circuit of the transmission 42 to control the gear ratio of the transmission 42 as a control object. FIG. 1 shows operation signals MS1 to MS3 to the fuel injection valve 16, the ignition device 18, and the transmission 42. The control device 70 also operates the first inverter 54 to control the rotation speed, and the like, which are control variables of the first motor generator 50 as a control object. The control device 70 also operates the second inverter 64 to control the torque, and the like, which are control variables of the second motor generator 60 as a control object.

[0012] When controlling the above-mentioned controlled variables, the control device 70 refers to the output signal Scr of the crank angle sensor 80 and the intake air amount Ga detected by the air flow meter 82. The control device 70 also refers to a shift variable Vsft, which is a variable indicating the shift position detected by the shift position sensor 84.

[0013] The control device 70 includes a CPU 72, a ROM 74, and a peripheral circuit 76. The CPU 72, the ROM 74, and the peripheral circuit 76 are capable of communicating with each other via a local network 78. Here, the peripheral circuit 76 includes a circuit for generating a clock signal that regulates the internal operation, a power supply circuit, a reset circuit, and the like. The control device 70 controls the control amount by the CPU 72 executing a program stored in the ROM 74.

[0014] Fig. 2 shows the procedure of the process executed by the control device 70. The process shown in Fig. 2 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74 at a predetermined crank angle period. In the following, the step number of each process is represented by a number preceded by "S".

[0015] In the series of processes shown in Fig. 2, the CPU 72 first obtains the time T30 required for the crankshaft 20 to rotate 30° CA (S10). This process is based on the output signal Scr. That is, the CPU 72 measures the time T30 from when one of the teeth 32 spaced apart by 30° CA is detected to when the other is detected. Next, the CPU 72 divides 30° CA by the time T30 to calculate the instantaneous speed ω, which is the speed required for the rotation of 30° CA (S12).

[0016] Then, the CPU 72 executes a process of substituting the instantaneous speed ω[m] for the instantaneous speed ω[m+1] with "m=0, 1, 2, 3, ..." and a process of substituting the instantaneous speed ω newly calculated in the process of S12 for the instantaneous speed ω[0] (S14). These processes are performed so that the variable in the parentheses after the instantaneous speed ω has a larger number the earlier it is. If the value of the variable in the parentheses is increased by one by these processes, it becomes the instantaneous speed ω 30° CA ago.

[0017] Next, the CPU 72 acquires the value of the shift variable Vsft (S16). Then, the CPU 72 determines whether or not the value of the shift variable Vsft indicates the D range (S18). When the CPU 72 determines that the range is the D range (S18: YES), the CPU 72 determines whether or not the current rotation angle of the crankshaft 20 is 30° CA from the compression top dead center of any of the cylinders #1 to #4 (S20). In other words, the CPU 72 determines whether or not the rotation angle is ATDC30°CA. When the CPU 72 determines that the rotation angle is ATDC30°CA (S20: YES), the CPU 72 calculates the energy change rate equivalent amount D1 (S22).

[0018] The energy change rate equivalent D1 is the value obtained by dividing the change in the square of the instantaneous speed ω during the time period T30 by the time T30. The value obtained by multiplying the square of the instantaneous speed ω by the moment of inertia corresponds to the rotational energy. Therefore, the square of the instantaneous speed is proportional to the rotational energy. Therefore, the energy change rate equivalent D1 is proportional to the time rate of change of the rotational energy.

[0019] Specifically, the CPU 72 calculates two energy change rate equivalents D1(0) and D1(1) chronologically spaced apart by time T30. The energy change rate equivalent D1(0) is calculated by subtracting the square of the instantaneous speed ω calculated by the previous S12 process from the square of the instantaneous speed ω calculated by the current S12 process. The energy change rate equivalent D1(1) is calculated by subtracting the square of the instantaneous speed ω calculated by the previous S12 process from the square of the instantaneous speed ω calculated by the process before that.

[0020] Next, the CPU 72 calculates a difference amount D2 (S24). The difference amount D2 is a value obtained by subtracting the energy change rate equivalent amount D1(1) from the energy change rate equivalent amount D1(0) and dividing the result by the time T30.

[0021] Next, the CPU 72 judges whether the difference amount D2 is smaller than the threshold value Dth (S26). This process is a process for judging whether the air-fuel ratio of the mixture in the cylinder judged by the process of S20 to have passed 30° CA from the compression top dead center is excessively lean. That is, the energy change rate equivalent amount D1(1) corresponds to the energy change rate in the period from BTDC 30° CA to TDC. During this period, it can be considered that the combustion energy of the mixture in the combustion chamber 14 is not generated. Therefore, the energy change rate equivalent amount D1(1) is an amount that quantifies the magnitude of the disturbance that hinders the rotation of the crankshaft 20. On the other hand, the energy change rate equivalent amount D1(0) corresponds to the energy change rate in the period from TDC to ATDC 30° CA. During this period, the combustion energy of the mixture in the combustion chamber 14 is converted into the rotation energy of the crankshaft 20. Therefore, the greater the combustion energy, the greater the energy change rate equivalent D1(0), but the greater the magnitude of the disturbance that impedes the rotation of the crankshaft 20, the smaller the amount. Therefore, the value obtained by subtracting the energy change rate equivalent D1(1) from the energy change rate equivalent D1(0) is the combustion energy equivalent. In the difference amount D2, the above subtracted value is divided by the time T30 for standardization purposes.

[0022] The CPU 72 sets the threshold value Dth to a smaller value when the rotation speed NE of the crankshaft 20 is high than when it is low. This is because when the rotation speed NE is high, the inertial energy is larger than when it is low, and therefore the fluctuation of the instantaneous speed ω is smaller. The rotation speed NE indicates the rotation speed of the crankshaft 20 over a period longer than the instantaneous speed ω. The rotation speed NE may be, for example, an average value of the rotation speed of the crankshaft 20 for one or more revolutions. The rotation speed NE is calculated by the CPU 72 based on the output signal Scr.

[0023] When the charging efficiency η is large, the CPU 72 calculates the threshold value Dth to be larger than when the charging efficiency η is small. This is because the larger the charging efficiency η, the larger the torque of the crankshaft 20 becomes, and therefore the larger the fluctuation of the instantaneous speed ω becomes. The charging efficiency η is calculated by the CPU 72 based on the intake air amount Ga and the rotation speed NE.

[0024] When the CPU 72 determines that the difference is equal to or greater than the threshold value Dth (S26: NO), the CPU 72 determines that the difference is normal (S28). On the other hand, when the CPU 72 determines that the difference is smaller than the threshold value Dth (S26: YES), the CPU 72 determines that the difference is lean abnormal (S30). Then, the CPU 72 executes a process of notifying the user of the abnormality by operating the warning light 86 shown in FIG. 1 (S32).

[0025] 2 when completing the processes of S28 and S32 or when a negative determination is made in the processes of S18 and S20. When the range is other than the D range, the CPU 72 executes a determination as to whether or not there is a lean abnormality based on the magnitude of the rotation fluctuation of the crankshaft 20. That is, the CPU 72 determines whether or not there is a lean abnormality based on a comparison between a pair of values ​​of the instantaneous speed ω adjacent to the compression top dead center during a period of 30° CA from the compression top dead center to ATDC30° CA and a threshold value.

[0026] Here, the operation and effects of this embodiment will be described. Figure 3 illustrates the transition of the instantaneous velocity ω and the energy change rate equivalent amount D1. In Figure 3, the dashed line indicates a state in which the injection amount in cylinder #4 is reduced by "5%". Also, the solid line indicates a state in which the injection amount in cylinder #4 is reduced by "25%". Here, it is assumed that a state in which the injection amount is reduced by "5%" is within the acceptable range, while a state in which the injection amount is reduced by "25%" is a lean abnormality that should be notified to the user.

[0027] As described above, in a range other than the D range, the CPU 72 determines the presence or absence of a lean abnormality by comparing the magnitude of the difference between the instantaneous speeds ω near the compression top dead center adjacent to each other with the threshold value. Here, in the D range, the inertia of the members mechanically connected to the crankshaft 20 is large compared to the N range, etc., and therefore the disturbance that hinders the rotation of the crankshaft 20 is large. In addition, the torque of the first motor generator 50, etc. may be superimposed on the crankshaft 20 as a disturbance component via the carrier C. Therefore, the difference between the instantaneous speeds ω is likely to have a similar value between normal and abnormal, which may make it difficult to set the threshold value.

[0028] In contrast, the difference amount D2 is an amount from which the effects of disturbances that impede the rotation of the crankshaft 20 have been removed, and therefore the difference between the normal state and the abnormal state can be made large. The relationship between the difference amount D2 and the threshold value Dth is shown in Fig. 4. As shown in Fig. 4, it is possible to distinguish between normal and abnormal states by the threshold value Dth.

[0029] According to the present embodiment described above, the following actions and effects can be obtained. (1) The difference amount D2 is set to an amount corresponding to the difference between the energy change rate equivalent amounts D1(0) and D1(1) that are spaced apart by 30° CA from each other. This makes it possible to suppress the influence of disturbances that impede the rotation of the crankshaft 20 from being different between the pair of energy change rate equivalent amounts D1, as compared to the case where the difference between the energy change rate equivalent amounts D1 that are spaced apart by 180° CA from each other is used. Therefore, the amount of combustion energy can be quantified with high accuracy by the difference amount D2.

[0030] (2) The damper 36 is mechanically connected to the crankshaft 20. In this case, the inertia of the rotating system including the crankshaft 20 is larger than when the damper 36 is not connected. When the inertia is large, the torque difference caused by the combustion in the cylinders #1 to #4 is less likely to appear as rotational fluctuation of the crankshaft 20 than when the inertia is small. Therefore, it becomes difficult to determine the presence or absence of a lean abnormality based on the rotational fluctuation of the crankshaft 20. Therefore, the difference amount D2 is particularly useful.

[0031] <Correspondence> The correspondence between the matters in the above embodiment and the matters described in the "Means for solving the problem" section is as follows: The injection abnormality determination device corresponds to the control device 70. The speed acquisition process corresponds to the process of S12. The energy change rate equivalent calculation process corresponds to the process of S22. The difference amount calculation process corresponds to the process of S24. The difference amount corresponds to the difference amount D2. The energy change rate equivalent corresponds to the energy change rate equivalent D1.

[0032] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0033] The instantaneous speed ω is not limited to the speed at which the crankshaft 20 rotates by 30° CA. For example, it may be the speed at which the crankshaft 20 rotates by 10° CA. However, it is preferable that the speed is in an angle range smaller than the interval at which the compression top dead center occurs.

[0034] The amount of change in energy rate is not limited to an amount corresponding to the difference between the squares of the instantaneous speed ω. For example, it may be an amount corresponding to the difference between the values ​​obtained by multiplying the square of the instantaneous speed ω by the moment of inertia I.

[0035] The square of a pair of instantaneous velocities ω used to calculate the energy change rate equivalent is not limited to the square of instantaneous velocities ω spaced apart by 30° CA from each other. For example, the square of instantaneous velocities ω spaced apart by 10° CA from each other may be used. Here, for the energy change rate equivalent calculated using the square of a pair of instantaneous velocities ω spaced apart by a predetermined angle, it is preferable that the predetermined angle is smaller than the interval between the occurrence of the compression top dead center. In particular, it is preferable that the predetermined angle is smaller than "1 / 2" of the interval between the occurrence of the compression top dead center. Note that the predetermined angle may be variably set according to the operating state of the internal combustion engine 10.

[0036] The pair of energy change rate equivalents D1 used to calculate the difference amount are not limited to the energy change rate equivalents D1 spaced apart by 30°. For example, the energy change rate equivalents D1 may be spaced apart by 10° CA. Here, for the difference amount calculated using the pair of energy change rate equivalents D1 spaced apart by a specified angle, it is preferable that the specified angle is an angle smaller than the interval between the occurrence of the compression top dead center. In particular, it is preferable that the specified angle is an angle smaller than "1 / 2" of the interval between the occurrence of the compression top dead center. Note that the specified angle may be variably set according to the operating state of the internal combustion engine 10.

[0037] The difference amount is not limited to the difference amount D2, but may be, for example, the difference between the energy change rate equivalent amounts D1. 2, the processes of S20 to S32 are executed only in the D range, but this is not limiting. The processes of S20 to S32 may be executed at all times, regardless of the shift range.

[0038] 2, the presence or absence of an abnormality in which the injection amount is smaller than the target injection amount is determined, but this is not limited to this. It may also be determined that there is an abnormality in which the injection amount is larger than the target injection amount when the difference amount D2 is larger than a predetermined threshold value.

[0039] The process for dealing with the abnormality when it is determined that there is an abnormality is not limited to a notification process such as turning on the warning light 86. For example, the process may be a process for increasing the command value of the injection amount for the fuel injection valve 16 of the cylinder determined to have an abnormality.

[0040] The vehicle does not necessarily need to be equipped with the transmission 42. The vehicle is not limited to a series-parallel hybrid vehicle. For example, it may be a parallel hybrid vehicle. Furthermore, the vehicle is not limited to a hybrid vehicle. For example, the vehicle may be a vehicle whose thrust generating device is only an internal combustion engine. [Explanation of symbols]

[0041] 10. Internal combustion engine 20…Crankshaft 30…Crank rotor 36…Damper 40...Planetary gear mechanism 42…Gearbox 44…Drive wheel 70...Control device

Claims

[Claim 1] Applied to an internal combustion engine having multiple cylinders, Execute a speed acquisition process, an energy change rate equivalent calculation process, a difference amount calculation process, and a determination process; the speed acquisition process is a process of acquiring a rotation speed of a crankshaft of the internal combustion engine, the energy change rate equivalent calculation process is a process of calculating an energy change rate equivalent, which is a variable indicating a time change in an amount proportional to the square of the rotation speed, the difference amount calculation process is a process of calculating a difference amount that is an amount proportional to a difference between a pair of energy change rate equivalent amounts before and after one compression top dead center, The determination process determines whether or not there is an abnormality in the amount of fuel injection of the internal combustion engine based on a comparison between the difference amount as an input variable and a threshold value.

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